How Common Is Signal-Intensity Increase in Optic Nerve Segments on 3D Double Inversion Recovery Sequences in Visually Asymptomatic Patients with Multiple Sclerosis?

BACKGROUND AND PURPOSE:In postmortem studies, subclinical optic nerve demyelination is very common in patients with MS but radiologic demonstration is difficult and mainly based on STIR T2WI. Our aim was to evaluate 3D double inversion recovery MR imaging for the detection of subclinical demyelinating lesions within optic nerve segments.MATERIALS AND METHODS:The signal intensities in 4 different optic nerve segments (ie, retrobulbar, canalicular, prechiasmatic, and chiasm) were evaluated on 3D double inversion recovery MR imaging in 95 patients with MS without visual symptoms within the past 3 years and in 50 patients without optic nerve pathology. We compared the signal intensities with those of the adjacent lateral rectus muscle. The evaluation was performed by a student group and an expert neuroradiologist. Statistical evaluation (the Cohen κ test) was performed.RESULTS:On the 3D double inversion recovery sequence, optic nerve segments in the comparison group were all hypointense, and an isointense nerve sheath surrounded the retrobulbar nerve segment. At least 1 optic nerve segment was isointense or hyperintense in 68 patients (72%) in the group with MS on the basis of the results of the expert neuroradiologist. Student raters were able to correctly identify optic nerve hypersignal in 97%.CONCLUSIONS:A hypersignal in at least 1 optic nerve segment on the 3D double inversion recovery sequence compared with hyposignal in optic nerve segments in the comparison group was very common in visually asymptomatic patients with MS. The signal-intensity rating of optic nerve segments could also be performed by inexperienced student readers.

MR imaging contributes to not only the diagnosis and differential diagnosis of MS but also the monitoring and follow-up of patients.¹ T1-weighted postcontrast, T2-weighted, proton-density, FLAIR, and double inversion recovery (DIR) images are recommended to detect acute and chronic demyelinating lesions in typical locations.^1–9Acute optic neuritis is an inflammatory demyelination of the optic nerve causing acute visual loss.^10–13 After recovery, patients are often visually asymptomatic, but careful visual testing by visually evoked potentials, optical coherence tomography, and visual disability evaluation may reveal persistent slight visual deficits.^14–17 These deficits are also observed in patients without any history of previous acute optic neuritis due to a suspected subclinical disease known as subclinical optic nerve demyelination.^14–17Acute optic neuritis is easily diagnosed on MR imaging by focal nerve swelling and segmental T2-weighted hyperintensity, especially on STIR images or on fat-suppressed T2-weighted images and by segmental gadolinium enhancement on T1-weighted fat-suppressed images.^10,18–22 The enhancement is present for a mean of 30 days after the onset of visual symptoms.^21,23–31Subclinical optic nerve demyelination, however, is not easily visible on MR imaging. Routine T2-weighted images without fat suppression and contrast-enhanced T1-weighted FSE images do not show any signal abnormality in the affected optic nerve. Fat-suppressed T2-weighted FSE images, especially STIR T2-weighted images, may detect a signal-intensity abnormality in subclinical optic nerve demyelination.^23,32,33 The highly diagnostic value of fat-suppressed FLAIR images and fat-suppressed 3D DIR images in the detection of any pathologic signal intensity in the optic nerve has been evaluated in acute optic nerve demyelination.^10,34,35 In a few patients with subclinical optic nerve demyelination, signal-intensity abnormalities have been reported on 3D FLAIR.³⁴ However, there are few data about the use of the 3D DIR sequence in the evaluation of subclinical optic nerve demyelination.³⁶In our department, patients with MS are routinely and regularly monitored for disease progression by a standard protocol with 3D FLAIR, 3D DIR, T2-weighted FSE, and 3D T1-weighted postcontrast images. 3D DIR is added to our standard protocol for improved detection of juxtacortical, cortical, and infratentorial demyelinating lesions.^1–9 On the basis of postmortem and clinical studies having already shown a high percentage of subclinical optic nerve demyelination with ongoing axonal loss in patients with MS,^37–41 we wanted to test 2 hypotheses: first, that it is possible to detect signal-intensity changes in optic nerve segments on the 3D DIR sequence without the additional application of a STIR T2-weighted sequence over the orbits in patients with MS without a history of clinically obvious visual loss and without a history of acute optic neuritis during the previous 3 years; and second, that the signal-intensity changes on 3D DIR are so obvious that even inexperienced readers can detect them. This second hypothesis is important because in our department, MR imaging examinations of patients with MS are evaluated not only by trained neuroradiologists but also general radiologists. Therefore, it is desirable that the lack of neuroradiologic experience be compensated by the application of an easily readable MR image, and the 3D DIR sequence is routinely acquired in our department for the follow-up of patients with MS.For comparison, the signal intensities of normal healthy optic nerve segments in patients evaluated by the identical 3D DIR sequence for different diseases (ie, epileptic seizures and posttraumatic sequelae) were analyzed as well.     

Ultrasound of the Hypoglossal Nerve in the Neck: Visualization and Initial Clinical Experience with Patients

BACKGROUND AND PURPOSE:The hypoglossal nerve, providing motor innervation for the tongue, can be affected in many diseases of the neck and skull base, leading to dysarthria, dysphagia, and ultimately atrophy of the tongue. We determined the feasibility of direct visualization of the hypoglossal nerve in the neck with ultrasound, testing this technique on healthy volunteers and evaluating it in clinical practice.MATERIALS AND METHODS:The study consisted of 4 parts: first, ultrasound-guided perineural ink injections along the course of the hypoglossal nerve at 24 sides of 12 fresh, nonembalmed cadaver necks. Subsequently, the specimens were dissected to confirm the correct identification of the nerve. The second part was examination of healthy volunteers with ultrasound and measurement of cross-sectional areas for generating reference data. The third part was scanning of healthy volunteers by 2 resident physicians with little and intermediate experience in ultrasound. Fourth was examination with ultrasound of patients with motor symptoms of the tongue.RESULTS:The hypoglossal nerve was correctly identified bilaterally in all cadaveric specimens (24/24) and all volunteers (33/33). The cross-sectional area ranged from 1.9 to 2.1 mm². The resident physicians were able to locate the nerve in 19 of 22 cases, demonstrating that locating the nerve is reproducible and feasible even with intermediate experience in ultrasound. Finally, alterations of the hypoglossal nerve in disease states could be depicted.CONCLUSIONS:Direct, reliable, and reproducible visualization of the extracranial hypoglossal nerve with ultrasound is feasible.

The hypoglossal nerve provides motor innervation for the entire tongue with the exception of the palatoglossal muscle. The nerve leaves the medulla oblongata between the olive and the pyramid in the preolivary groove, passes through the premedullary cistern, and exits the skull through the hypoglossal canal. Inferior to the skull base, the nerve descends lateral to the carotid artery, traveling with the glossopharyngeal, vagal, and accessory nerves; the carotid artery; and the internal jugular vein within the carotid space. At the level of the mandibular angle, the nerve courses anteriorly, caudal to the posterior belly of the digastric muscle, toward the hyoid bone. Here, the nerve enters the submandibular space, passes between the mylohyoid and the hyoglossal muscles into the sublingual space, and finally enters the body of the tongue.¹A lesion of the hypoglossal nerve can cause dysarthria, dysphagia, and tongue paralysis, and unilateral atrophy of the tongue muscles may result. Denervation of the tongue can be secondary to radiation therapy due to formation of fibrotic tissue around the nerve, infection, lymphadenopathy, tumor entrapping or infiltrating the nerve, neurogenic tumors arising within the nerve, or trauma, with iatrogenic trauma resulting from carotid endarterectomy, neck dissection, or tonsillectomy being among the more common causes of hypoglossal nerve dysfunction. There are also reports of carotid and vertebral artery dissections leading to hypoglossal nerve injury.^2–18 In a large case series of hypoglossal nerve palsies, the site of the lesion could not be localized in 6%.⁹In the radiologic diagnostic work-up, a segmental imaging approach is advised.^19–21 The medullary, cisternal, and skull base segments can be well examined with the existing protocols of MR imaging and CT. In the carotid and submandibular spaces, these imaging modalities are also recommended, but the nerve itself is usually not depicted.^19,20,22 We are not aware of any study of the feasibility of the direct visualization of the extracranial hypoglossal nerve, though ultrasound (US) has been increasingly used to visualize peripheral nerves to diagnose and localize pathologies affecting them.^23,24The aim of our study was to test the feasibility of direct visualization of the extracranial hypoglossal nerve with US in fresh cadavers, healthy volunteers, and patients with a suspected lesion of the hypoglossal nerve. A secondary objective was to provide data on the cross-sectional area of the hypoglossal nerve in our volunteer sample as a reference.     

Cranial Arachnoid Protrusions and Contiguous Diploic Veins in CSF Drainage

BACKGROUND AND PURPOSE:Studies have suggested that arachnoid villi or granulations found in the walls of the cranial dural sinuses, olfactory mucosa, and cranial nerve sheaths function as outlets for intracranial CSF. However, their role as CSF outlets has not yet been verified. Here we show that arachnoid protrusions and contiguous diploic veins provide an alternative drainage route for intracranial CSF.MATERIALS AND METHODS:Four hundred patients with intact skull, dura mater, and dural sinuses underwent MR imaging to explore arachnoids protruding into the skull and diploic veins. Patients with symptoms of increased intracranial pressure or intracranial hypotension were excluded. For 15 patients undergoing craniotomy, both peripheral and diploic venous blood was collected. Albumin and the CSF-specific biomarkers were measured by enzyme-linked immunosorbent assay.RESULTS:With MR imaging, arachnoid protrusions into the skull and contiguous diploic veins were consistently identified throughout the cranium with their characteristic appearance depending on the cranial region. In addition, elevated amounts of prostaglandin D synthase and cystatin C were confirmed in diploic veins compared with peripheral venous blood.CONCLUSIONS:Diploic veins are distributed ubiquitously throughout the cranium. A portion of the intracranial CSF may be drained through arachnoid protrusions and contiguous diploic veins.

It has been suggested that arachnoid villi or granulations found in the walls of the cranial dural sinuses, olfactory mucosa, and cranial nerve sheaths function as outlets for intracranial CSF.^1–4 Arachnoid granulations located adjacent to or in the cranial dural sinuses have been explored by using a variety of methods, including neuroimaging,^5–15 postmortem dissection,^5,16,17 investigations by using casting material,¹⁸ and ex vivo studies.¹ However, no report has actually shown the process of CSF absorption in vivo. Diploic veins (DVs) are present throughout the cranium; however, their distribution and functional implications have rarely been documented.^1,19 One previous MR imaging study proposed the hypothesis that major pathways of the DVs function as CSF drainage routes.¹⁹Lipocalin-type prostaglandin D synthase (PGDS) is a major endogenous β chaperone that is present in the brain and secreted into the CSF.^20,21 It is thought to be a CSF-specific biomarker and sensitive to inflammatory demyelinating disease,²² Alzheimer disease,²³ and normal pressure hydrocephalus.¹⁹ Cystatin C (CysC), a low-molecular-weight cysteine proteinase inhibitor, is known to be expressed in greater amounts in CSF compared with plasma.²⁴ The purpose of the present study was to demonstrate that arachnoid pouches protruding into the skull (APs) and contiguous diploic veins provide an alternative CSF drainage route by high-resolution MR imaging; and we also aimed to measure CSF-specific biomarkers, PGDS, and CysC.     

The Diagnostic Value of CT Myelography,MR Myelography,and Both in Neonatal Brachial Plexus Palsy

BACKGROUND AND PURPOSE:Although most infants with brachial plexus palsy recover function spontaneously, approximately 10–30% benefit from surgical treatment. Pre-operative screening for nerve root avulsions is helpful in planning reconstruction. Our aim was to compare the diagnostic value of CT myelography, MR myelography, and both against a surgical criterion standard for detection of complete nerve root avulsions in birth brachial plexus palsy.MATERIALS AND METHODS:Nineteen patients who underwent a preoperative CT and/or MR myelography and subsequent brachial plexus exploration were included. Imaging studies were analyzed for the presence of abnormalities potentially predictive of nerve root avulsion. Findings of nerve root avulsion on surgical exploration were used as the criterion standard to assess the predictive value of imaging findings.RESULTS:Ninety-five root levels were examined. When the presence of any pseudomeningocele was used as a predictor, the sensitivity was 0.73 for CT and 0.68 for MR imaging and the specificity was 0.96 for CT and 0.97 for MR imaging. When presence of pseudomeningocele with absent rootlets was used as the predictor, the sensitivity was 0.68 for CT and 0.68 for MR imaging and the specificity was 0.96 for CT and 0.97 for MR imaging. The use of both CT and MR imaging did not increase diagnostic accuracy. Rootlet findings in the absence of pseudomeningocele were not helpful in predicting complete nerve root avulsion.CONCLUSIONS:Findings of CT and MR myelography were highly correlated. Given the advantages of MR myelography, it is now the single technique for preoperative evaluation of nerve root avulsion at our institution.

Brachial plexus palsy occurs in approximately 1 in 1000 neonates.^1,2 Downward traction on the shoulder girdle produces stereotyped patterns of plexus injury.³ Nerve lesions occur first at higher levels, with more severe traction resulting in progressive inferior extension.^3,4 More superior nerve injury is typically extraforaminal, at the level of the superior trunks, because a well-developed investing fascia protects the upper nerve roots from proximal traction. In contrast, inferior lesions are more often intraforaminal, manifesting as either partial or complete avulsion of the nerve root.⁴Clinical manifestations and spontaneous recovery depend on the extent, location, and type of nerve lesions. The clinical presentation can generally be grouped into 1 of 4 patterns outlined by Narakas⁵: Type I involves C5 and C6 deficits (Erb-Duchenne type) with loss of shoulder abduction, shoulder external rotation, elbow flexion, and forearm supination. Type II involves C5 to C7/C8 deficits, resulting in a “waiter''s tip” posture from additional loss of wrist extension. Type III involves C5 to C8/T1 deficits, resulting in an arm that is generally paralyzed. Type IV involves C5 to T1 and the sympathetic chain, resulting in a flail arm with Horner syndrome. Upward traction on the brachial plexus can result in isolated lower plexus deficits that manifest as paralysis of the hand only.^6,7 This pattern is known as Klumpke palsy.The decision to proceed with surgical exploration and reconstruction is based on the clinical presentation and progression. While 70%–90% of infants are treated with therapy alone, 10%–30% have indications for surgical treatment.^8–11 Nerve injuries distal to the intervertebral foramen can be reconstructed by using nerve grafts, whereas intraforaminal nerve root avulsions require nerve transfer. While both partial and complete nerve root avulsions are described,^12,13 there is no clear consensus on the surgical approach to partial nerve root avulsions. Preoperative imaging capable of accurately identifying complete nerve root avulsions and distinguishing them from extraforaminal nerve injuries is, therefore, critical for optimal surgical planning.The current standard for preoperative assessment of nerve root avulsions in infants is CT myelography.^12,14–19 A pseudomeningocele is suggestive of nerve root avulsion, and the additional finding of absent rootlets traversing the pseudomeningocele greatly increases the specificity of this finding.¹⁴ CT myelography requires a lumbar puncture for injection of intrathecal contrast, with attendant risks of infection and seizure.^20–22 Recent studies have also raised concern for malignancy with early exposure of children to radiation.^23,24 MR myelography can be performed without injection of contrast and is a promising alternative.^17,25 However, the performance of MR myelography for predicting nerve root avulsion is not yet established²⁶ in neonatal brachial plexus injury, and the diagnostic value of MR myelography has yet to be compared with CT myelography in this setting.The purpose of this study was to determine the predictive value of CT myelography, MR myelography, and both CT and MR myelography for detecting complete nerve root avulsions in neonatal brachial plexus palsy, by using a surgical criterion standard.     

Visualization of the Peripheral Branches of the Mandibular Division of the Trigeminal Nerve on 3D Double-Echo Steady-State with Water Excitation Sequence

BACKGROUND AND PURPOSE:Although visualization of the extracranial branches of the cranial nerves has improved with advances in MR imaging, only limited studies have assessed the detection of extracranial branches of the mandibular nerve (V3). We investigated the detectability of the branches of V3 on a 3D double-echo steady-state with water excitation sequence.MATERIALS AND METHODS:We retrospectively evaluated the detectability of the 6 branches of the V3, the masseteric, buccal, auriculotemporal, lingual, inferior alveolar, and mylohyoid nerves, by using a 5-point scale (4, excellent; 3, good; 2, fair; 1, poor; and 0, none) in 86 consecutive patients who underwent MR imaging with the 3D double-echo steady-state with water excitation sequence. Weighted κ analysis was used to calculate interobserver variability among the 3 readers.RESULTS:The detection of the lingual and inferior alveolar nerves was the most successful, with excellent average scores of 3.80 and 3.99, respectively. The detection of the masseteric, the buccal, and the auriculotemporal nerves was good, with average scores of 3.31, 2.67, and 3.11, respectively. The mylohyoid nerve was difficult to detect with poor average scores of 0.62. All nerves had excellent interobserver variability across the 3 readers (average weighted κ value, 0.95–1.00).CONCLUSIONS:The 3D double-echo steady-state with water excitation sequence demonstrated excellent visualization of the extracranial branches of V3 in most patients. The 3D double-echo steady-state with water excitation sequence has the potential for diagnosing V3 pathologies and preoperatively identifying peripheral cranial nerves to prevent surgical complications.

Cranial nerve deficits are not uncommon, and there are many pathologic processes that can affect the cranial nerves.^1–10 Unfortunately, the physical examination findings are often nonspecific for differentiating among these pathologic causes, and imaging plays a crucial role in diagnosing pathologic processes affecting the cranial nerves. With increasing spatial and contrast resolution of cross-sectional imaging, better visualization of the cranial nerves and their major branches has become possible, but the delineation of the entire course of the extracranial segments of the cranial nerves still remains a diagnostic challenge.^11–17The trigeminal nerve has the largest distribution of innervation among all the cranial nerves in the suprahyoid neck. Even though the mandibular nerve (V3) is the largest division of the trigeminal nerve, there have been only limited studies investigating the visualization of the extracranial segments of V3 with MR imaging. Several prior studies have focused on imaging the extracranial segments of V3 by using a T1-weighted fast-spoiled gradient recalled-echo sequence with fat suppression,⁹ a T1-weighted MPRAGE sequence with water excitation fat suppression,¹⁸ or a diffusion tensor tractography sequence,¹⁹ but these studies evaluated only the inferior alveolar nerve. Another study used FIESTA and fast-spoiled gradient recalled-echo sequences to evaluate the entire V3 nerve, but the extracranial peripheral V3 branches were not well-demonstrated, with the exception of the inferior alveolar and lingual nerves.¹³The 3D double-echo steady-state with water excitation (3D-DESS-WE) sequence is a recently introduced MR imaging technique that can delineate the peripheral cranial nerves as high-signal-intensity structures.²⁰ At our institution, this sequence has been added to our standard MR imaging protocol of the salivary glands and has been used routinely to evaluate the intraparotid facial nerve and salivary ducts within the salivary glands since October 2012. The purpose of this study was to investigate the detectability of the extracranial peripheral branches of V3 on the 3D-DESS-WE sequence.     

Enhanced Repair Effect of Toll-Like Receptor 4 Activation on Neurotmesis: Assessment Using MR Neurography

BACKGROUND AND PURPOSE:Alternative use of molecular approaches is promising for improving nerve regeneration in surgical repair of neurotmesis. The purpose of this study was to determine the role of MR imaging in assessment of the enhanced nerve regeneration with toll-like receptor 4 signaling activation in surgical repair of neurotmesis.MATERIALS AND METHODS:Forty-eight healthy rats in which the sciatic nerve was surgically transected followed by immediate surgical coaptation received intraperitoneal injection of toll-like receptor 4 agonist lipopolysaccharide (n = 24, study group) or phosphate buffered saline (n = 24, control group) until postoperative day 7. Sequential T2 measurements and gadofluorine M-enhanced MR imaging and sciatic functional index were obtained over an 8-week follow-up period, with histologic assessments performed at regular intervals. T2 relaxation times and gadofluorine enhancement of the distal nerve stumps were measured and compared between nerves treated with lipopolysaccharide and those treated with phosphate buffered saline.RESULTS:Nerves treated with lipopolysaccharide injection achieved better functional recovery and showed more prominent gadofluorine enhancement and prolonged T2 values during the degenerative phase compared with nerves treated with phosphate buffered saline. T2 values in nerves treated with lipopolysaccharide showed a more rapid return to baseline level than did gadofluorine enhancement. Histology exhibited more macrophage recruitment, faster myelin debris clearance, and more pronounced nerve regeneration in nerves treated with toll-like receptor 4 activation.CONCLUSIONS:The enhanced nerve repair with toll-like receptor 4 activation in surgical repair of neurotmesis can be monitored by using gadofluorine M-enhanced MR imaging and T2 relaxation time measurements. T2 relaxation time seems more sensitive than gadofluorine M-enhanced MR imaging for detecting such improved nerve regeneration.

Neurotmesis is the most common type of traumatic peripheral nerve injury and could result in complete paralysis of an affected limb or development of intractable neuropathic pain.¹ Peripheral nerve repair, either by direct suturing of the nerve ends or by nerve grafting, remains the standard treatment of choice. However, despite advancements of microsurgical techniques and different repair methods, full functional outcome, especially of motor function, is rarely achievable.² Alternative use of Schwann cell or stem cell–based tissue-engineered conduits has been shown to exert a beneficial effect on peripheral nerve repair. However, the number of regenerating neurons following injury and repair is still suboptimal.³ Other strategies, particularly the use of molecular approaches, are promising for improving nerve regeneration in surgical repair of neurotmesis.⁴The success of nerve regeneration depends largely on the severity of the initial injury and resultant degenerative changes.⁵ A variety of cellular and molecular mechanisms are found to regulate Wallerian degeneration and axonal regeneration in the injured peripheral nerve.⁶ Recent studies demonstrated that toll-like receptor (TLR) signaling is critical for Wallerian degeneration and functional recovery in peripheral nerve injury⁷ and spinal cord injury.⁸ The use of TLR4 agonist lipopolysaccharide (LPS) was able to accelerate myelin phagocytosis during Wallerian degeneration in the crushed sciatic nerve and injured spinal cord, thereby promoting recovery of nerve functions.^7,8MR neurography, including quantitative T2 measurements, has been widely used to evaluate traumatic injuries of peripheral nerves,^9,10 to monitor native process of nerve recovery,¹¹ and to reveal enhanced nerve regeneration by stem cell transplantation in peripheral nerve injuries.¹² Taking advantage of a strong affinity for degenerating nerve tissues, gadofluorine M-enhanced MR imaging has been successfully applied to monitor nerve regeneration in transected nerve repaired with tissue-engineered nerve conduits.¹³ However, little is known about the use of MR neurography to evaluate nerve repair with surgical coaptation in presence of simultaneous TLR4 pathway activation.The purpose of this study was to observe the longitudinal changes of nerve repair on MR imaging and then to determine whether the enhanced nerve regeneration with use of TLR4 activation in surgical repair of neurotmesis could be assessed by gadofluorine M-enhanced MR imaging or nerve T2 relaxation time measurement.     

Predictive Models in Differentiating Vertebral Lesions Using Multiparametric MRI

BACKGROUND AND PURPOSE:Conventional MR imaging has high sensitivity but limited specificity in differentiating various vertebral lesions. We aimed to assess the ability of multiparametric MR imaging in differentiating spinal vertebral lesions and to develop statistical models for predicting the probability of malignant vertebral lesions.MATERIALS AND METHODS:One hundred twenty-six consecutive patients underwent multiparametric MRI (conventional MR imaging, diffusion-weighted MR imaging, and in-phase/opposed-phase imaging) for vertebral lesions. Vertebral lesions were divided into 3 subgroups: infectious, noninfectious benign, and malignant. The cutoffs for apparent diffusion coefficient (expressed as 10⁻³ mm²/s) and signal intensity ratio values were calculated, and 3 predictive models were established for differentiating these subgroups.RESULTS:Of the lesions of the 126 patients, 62 were infectious, 22 were noninfectious benign, and 42 were malignant. The mean ADC was 1.23 ± 0.16 for infectious, 1.41 ± 0.31 for noninfectious benign, and 1.01 ± 0.22 mm²/s for malignant lesions. The mean signal intensity ratio was 0.80 ± 0.13 for infectious, 0.75 ± 0.19 for noninfectious benign, and 0.98 ± 0.11 for the malignant group. The combination of ADC and signal intensity ratio showed strong discriminatory ability to differentiate lesion type. We found an area under the curve of 0.92 for the predictive model in differentiating infectious from malignant lesions and an area under the curve of 0.91 for the predictive model in differentiating noninfectious benign from malignant lesions. On the basis of the mean ADC and signal intensity ratio, we established automated statistical models that would be helpful in differentiating vertebral lesions.CONCLUSIONS:Our study shows that multiparametric MRI differentiates various vertebral lesions, and we established prediction models for the same.

MR imaging is the preferred technique in the diagnostic work-up of benign and malignant vertebral lesions. Morphologic criteria alone could not differentiate benign and malignant spinal lesions in 6%–21% of cases.^1–3 Due to the limited specificity of conventional MR imaging,⁴ radiologists often have trouble differentiating common spinal pathologies such as osteoporotic vertebral collapse, infectious spondylodiscitis, and metastasis. Recently, multiparametric MR imaging (mpMRI) has shown the ability to localize, detect, and stage various diseases.^5–8 The mpMRI approach combines anatomic sequences (T1- and T2-weighted MR imaging) with functional imaging sequences. Functional and quantitative MR imaging methods, such as DWI, dynamic contrast-enhanced MR imaging, and in-phase/opposed-phase imaging, measure the Brownian motion of water molecules, regional vascular properties of the tumor, and fat quantification, respectively.^6–9DWI has been used in the differentiation of benign and malignant spinal lesions.^10–12 Signal characteristics of vertebral lesions were evaluated on DWI for qualitative assessment, and the ADC was calculated for quantitative analysis. In general, malignant lesions yield lower ADC compared with noninfectious benign and infectious lesions due to increased cellularity and decreased extracellular space in malignant lesions.^10–12 In-phase/opposed-phase MR imaging quantifies fat in tissues and has been used in lesions of the adrenal gland and liver.^13–17 It has also been used in diagnostic work-up of spinal lesions, and the results demonstrated a significant difference in the signal intensity ratio (SIR) between benign and malignant vertebral lesions.^9,18–21The hypothesis for this study was that the mpMRI approach would increase the discriminatory ability of different vertebral lesions. The aim of the present study was to evaluate the ability of mpMRI in differentiating vertebral lesions and to establish statistical models for predicting the probability of malignant (GPM) lesions compared with noninfectious benign (GPN) and infectious (GPI) ones. The cutoffs of the ADC and SIR values were obtained to differentiate GPM lesions from GPI and GPN lesions. Furthermore, we considered GPI and GPN as all benign compared with the malignant lesions. The cutoff values of the ADC and SIR for differentiating malignant from all benign lesions were also obtained.Although attempts have been made to assess the role of quantitative DWI or in-phase/opposed-phase imaging in differentiating vertebral lesions, to the best of our knowledge, no previous study has evaluated the ability of mpMRI to differentiate malignant or infectious lesions from noninfectious benign lesions.     

Meta-Analysis of CSF Diversion Procedures and Dural Venous Sinus Stenting in the Setting of Medically Refractory Idiopathic Intracranial Hypertension

BACKGROUND AND PURPOSE:In medically refractory idiopathic intracranial hypertension, optic nerve sheath fenestration or CSF shunting is considered the next line of management. Venous sinus stenosis has been increasingly recognized as a treatable cause of elevated intracranial pressure in a subset of patients. In this article, we present the results of the largest meta-analysis of optic nerve sheath fenestration, CSF shunting, and dural venous sinus stenting. This is the only article that compares these procedures, to our knowledge.MATERIALS AND METHODS:We performed a PubMed search of all peer-reviewed articles from 1988 to 2014 for patients who underwent a procedure for medically refractory idiopathic intracranial hypertension.RESULTS:Optic nerve sheath fenestration analysis included 712 patients. Postprocedure, there was improvement of vision in 59%, headache in 44%, and papilledema in 80%; 14.8% of patients required a repeat procedure with major and minor complication rates of 1.5% and 16.4%, respectively. The CSF diversion procedure analysis included 435 patients. Postprocedure, there was improvement of vision in 54%, headache in 80%, and papilledema in 70%; 43% of patients required at least 1 additional surgery. The major and minor complication rates were 7.6% and 32.9%, respectively. The dural venous sinus stenting analysis included 136 patients. After intervention, there was improvement of vision in 78%, headache in 83%, and papilledema in 97% of patients. The major and minor complication rates were 2.9% and 4.4%, respectively. Fourteen additional procedures were performed with a repeat procedure rate of 10.3%. Three patients had contralateral stent placement, while 8 had ipsilateral stent placement within or adjacent to the original stent. Only 3 patients required conversion to CSF diversion or 2.2% of patients with stents.CONCLUSIONS:Patients with medically refractory idiopathic intracranial hypertension have traditionally undergone a CSF diversion procedure as the first intervention. This paradigm may need to be re-examined, given the high technical and clinical success and low complication rates with dural venous sinus stenting.

Idiopathic intracranial hypertension (IIH), previously referred to as pseudotumor cerebri and benign intracranial hypertension, is a syndrome defined by elevated intracranial hypertension without radiographic evidence of a mass lesion in the brain.¹ The overall prevalence of IIH in North America has been estimated to be 0.9–1.07/100,000^2,3; however, in women with obesity between 20 and 44 years of age, the prevalence rises to 15–19/100,000.²Although headache is the most common presenting symptom, seen in 92%–94% of patients,^4,5 IIH also represents a significant cause of chronic headaches. In some patients, there may be vision changes,^6–9 which, if not corrected, may progress to permanent visual loss.^10,11The standard medical treatment includes weight loss, acetazolamide, diuretics, and repeat high-volume lumbar punctures. In patients with medically refractory IIH or progressive visual loss, a CSF-diversion procedure (lumboperitoneal shunt, ventriculoperitoneal shunts, or optic nerve sheath fenestration) is considered the next line of management.^9,12CSF diversion procedures in the setting of medically refractory IIH have been described in the literature dating back to 1955, by Jackson and Snodgrass.^13,14 These studies are level 3 evidence, comprising case series and individual case reports. There are no prospective randomized controlled studies on lumboperitoneal shunt, ventriculoperitoneal shunts, or optic nerve sheath fenestration, to our knowledge.Venous sinus stenosis has been increasingly recognized as a treatable cause of elevated intracranial pressure. Venous sinus stent placement was first described by Higgins et al.¹⁵ During the past 20 years, an increasing number of case reports and larger case series have described dural venous sinus stent placement, and reported high rates of technical success and favorable clinical outcomes.^6,7,16–21In this article, we present the results of the largest meta-analysis of optic nerve sheath fenestration, CSF diversion procedure, and venous sinus stent placement for medically refractory IIH from 1988 to present. We then compare these interventions with a focus on symptom improvement, complications, and the need for repeat procedures.     

Localizing the L5 Vertebra Using Nerve Morphology on MRI: An Accurate and Reliable Technique

BACKGROUND AND PURPOSE:Multiple methods have been used to determine the lumbar vertebral level on MR imaging, particularly when full spine imaging is unavailable. Because postmortem studies show 95% accuracy of numbering the lumbar vertebral bodies by counting the lumbar nerve roots, attention to lumbar nerve morphology on axial MR imaging can provide numbering clues. We sought to determine whether the L5 vertebra could be accurately localized by using nerve morphology on MR imaging.MATERIALS AND METHODS:One hundred eight cases with full spine MR imaging were numbered from the C2 vertebral body to the sacrum with note of thoracolumbar and lumbosacral transitional states. The origin level of the L5 nerve and iliolumbar ligament were documented in all cases. The reference standard of numbering by full spine imaging was compared with the nerve morphology numbering method. Five blinded raters evaluated all lumbar MRIs with nerve morphology technique twice. Prevalence and bias-adjusted κ were used to measure interrater and intrarater reliability.RESULTS:The L5 nerve arose from the 24th presacral vertebra (L5) in 106/108 cases. The percentage of perfect agreement with the reference standard was 98.1% (95% CI, 93.5%–99.8%), which was preserved in transitional and numeric variation states. The iliolumbar ligament localization method showed 83.3% (95% CI, 74.9%–89.8%) perfect agreement with the reference standard. Inter- and intrarater reliability when using the nerve morphology method was strong.CONCLUSIONS:The exiting L5 nerve can allow accurate localization of the corresponding vertebrae, which is essential for preprocedure planning in cases where full spine imaging is not available. This neuroanatomic method displays higher agreement with the reference standard compared with previously described methods, with strong inter- and intrarater reliability.

Accurate and reliable spine numbering is important for the diagnosis of pathology and preprocedure planning. This can be challenging in patients with vertebral numeric variation (VNV) or lumbosacral transitional vertebrae (LSTV), particularly when full spine imaging is unavailable. VNV refers to the variation of the total number of presacral vertebrae (PSV). Approximately 89% of the population have 24 PSV (5 lumbar-type vertebrae), 8% have 25 PSV (6 lumbar-type vertebrae), and 3% have 23 PSV (4 lumbar-type vertebrae).¹ LSTV are congenital spinal anomalies in which an elongated transverse process of the last lumbar vertebra fuses with the “first” sacral segment to varying degrees.² The morphologic variation of LSTV can range from partial/complete L5 sacralization to partial/complete S1 lumbarization.^3,4 The prevalence of LSTV in the population varies throughout the literature because of differences in definition and diagnostic modalities.^1,4–6 LSTV can also vary with sex, with lumbarization of S1 seen more commonly in women and sacralization found to be more common in men.³ A person can have VNV without LSTV, or conversely, one can have LSTV without VNV.¹ Approximately 5% of subjects have been found to have both.¹Multiple anatomic landmarks have been used to determine the lumbar vertebral level in cases without full spine imaging. A leading method of localizing the iliolumbar ligament, most frequently arising from L5, has been found less accurate in the setting of LSTV and VNV.^7–11 Other landmarks, including the level of the conus, right renal artery, superior mesenteric artery, aortic bifurcation, and iliac crest height, are also less accurate.^9,12–14 Choosing the appropriate level for surgical or interventional procedures is essential and relies on accurately and reliably numbering the spine in patients with “normal” anatomy as well as those with variant or transitional anatomy.^4,15 This is especially important in patients with LSTV and/or VNV undergoing surgical planning, as up to 32% of neurosurgeons have reported an event of wrong-level spinal surgery occurring at least once in their careers.¹⁶ LSTV can also create challenges for approach in interventional pain procedures and can increase the risk of iatrogenic vascular injury.¹⁷Multiple imaging modalities have been used to evaluate LSTV and VNV, with MR imaging found to be most reliable.¹⁸ Anteroposterior radiographs have demonstrated high intermodality agreement with MR imaging.¹⁹ Studies show that one can accurately number the vertebrae by counting down from C2 to the sacrum on sagittal MR imaging by using a cross-referencing tool.^1,8,19,20 Although most counting methods have focused on the ossified structures, 1 postmortem study numbered the vertebrae by dorsal spinal nerve morphology and found up to 95% probability that the lower spinal nerves correspond to their respective spinal segment.²¹ We hypothesized that nerve morphology on lumbar spine MR imaging would aid in L5 vertebra localization, particularly when full spine imaging was not available. We aimed 1) to determine whether MR imaging morphologic features of the lumbar nerves could be used to distinguish the lower lumbar levels and 2) to apply these characteristics in localizing the L5 vertebra.     

Meta-Analysis of Diffusion Metrics for the Prediction of Tumor Grade in Gliomas

BACKGROUND AND PURPOSE:Diffusion tensor metrics are potential in vivo quantitative neuroimaging biomarkers for the characterization of brain tumor subtype. This meta-analysis analyzes the ability of mean diffusivity and fractional anisotropy to distinguish low-grade from high-grade gliomas in the identifiable tumor core and the region of peripheral edema.MATERIALS AND METHODS:A meta-analysis of articles with mean diffusivity and fractional anisotropy data for World Health Organization low-grade (I, II) and high-grade (III, IV) gliomas, between 2000 and 2013, was performed. Pooled data were analyzed by using the odds ratio and mean difference. Receiver operating characteristic analysis was performed for patient-level data.RESULTS:The minimum mean diffusivity of high-grade gliomas was decreased compared with low-grade gliomas. High-grade gliomas had decreased average mean diffusivity values compared with low-grade gliomas in the tumor core and increased average mean diffusivity values in the peripheral region. High-grade gliomas had increased FA values compared with low-grade gliomas in the tumor core, decreased values in the peripheral region, and a decreased fractional anisotropy difference between the tumor core and peripheral region.CONCLUSIONS:The minimum mean diffusivity differs significantly with respect to the World Health Organization grade of gliomas. Statistically significant effects of tumor grade on average mean diffusivity and fractional anisotropy were observed, supporting the concept that high-grade tumors are more destructive and infiltrative than low-grade tumors. Considerable heterogeneity within the literature may be due to systematic factors in addition to underlying lesion heterogeneity.

Diffusion tensor imaging is an MR imaging technique that can quantify diffusion of water in the brain and characterize the structural integrity of white matter tracts.^1–3 Multiple studies have examined the ability of basic diffusion tensor metrics such as mean diffusivity (MD) or the apparent diffusion coefficient and fractional anisotropy (FA) to discriminate the tumor grade of gliomas. Disruption of normal white matter structural integrity by primary glial neoplasms should theoretically reduce fractional anisotropy and increase mean diffusivity.Mean diffusivity is positively correlated with decreased tumor cellular density and increased patient survival, and significant effects are reported in several studies with respect to discriminating tumor grade specifically by using minimum mean diffusivity (minMD).^4–9 In contradistinction, there is no definitive consensus on the ability of fractional anisotropy to assess tumor grade, cellular density, and parenchymal infiltration or to prognosticate patient survival.^7,10–21 We performed a quantitative meta-analysis of the existing literature to determine the statistical consensus of mean diffusivity and fractional anisotropy in distinguishing tumor grade of gliomas, separately examining the identifiable tumor core and region of peripheral signal abnormality.     

Vision Outcomes and Major Complications after Endovascular Coil Embolization of Ophthalmic Segment Aneurysms

BACKGROUND AND PURPOSE:As aneurysms arising from the ophthalmic segment of the internal carotid artery increase in size, they can compress the optic nerve, prompting patients to present with visual disturbances. The purpose of this article is to describe the clinical and angiographic results with an emphasis on visual outcomes following the endovascular treatment of ophthalmic segment ICA aneurysms.MATERIALS AND METHODS:The records of 1254 patients who presented for endovascular treatment of a cerebral aneurysm were retrospectively reviewed to identify 65 consecutive patients who underwent coil embolization of an ophthalmic segment ICA aneurysm. The clinical records, treatment reports, and imaging were reviewed with a focus on visual outcomes.RESULTS:Twenty-two of the 65 patients (34%) who presented for treatment of an ophthalmic aneurysm reported a visual disturbance at presentation. Fifteen of the 22 patients (68%) experienced an improvement in their symptoms after treatment. Overall, patients with visual symptoms were significantly more likely to benefit from treatment than to have a decline in vision (P = .03). The overall morbidity was 4%, and mortality was 0%. The retreatment rate was high at 30%, though this was disproportionately weighted by an 86% retreatment rate in patients with ruptured aneurysms.CONCLUSIONS:Patients with visual symptoms attributable to ophthalmic segment ICA aneurysms undergoing endovascular coil embolization were statistically more likely to experience an improvement in their vision than to have worsening or unchanged vision. Coiling was associated with a low morbidity rate, though an elevated retreatment rate.

Aneurysms arising from the ophthalmic segment of the internal carotid artery account for approximately 5% of all intracranial aneurysms.^1,2 As these aneurysms increase in size, they can compress the optic nerve, prompting the patient to present with visual disturbances, often involving the inferior and/or nasal fields first.^2,3 Both surgical and endovascular treatment of these aneurysms have shown the potential to improve visual disturbances if occurring early.^2,4–11 However, treatment of these aneurysms is not without its own set of inherent risks. Retinal artery occlusion or delayed optic ischemia may occur after either surgical or endovascular repair.^12–14 A review of recent surgical literature suggests a permanent morbidity ranging from 3% to 38% following treatment of an ophthalmic segment ICA aneurysm.^{3,5,6,10,15–18} This morbidity includes a risk of new or worsened visual disturbance in 2%–30% of surgically treated patients and 3%–8% of endovascularly treated patients.^3,5,6,15,16This article assesses the angiographic and clinical outcomes of 65 consecutive patients who presented for initial treatment of an ophthalmic segment ICA aneurysm via an endovascular approach. Our goal is to describe the clinical and angiographic outcomes with an emphasis on visual outcomes following the endovascular treatment of ophthalmic segment aneurysms.     

Ethanol Ablation of Ranulas: Short-Term Follow-Up Results and Clinicoradiologic Factors for Successful Outcome

BACKGROUND AND PURPOSE:Surgical excision of an affected sublingual gland for treatment of a ranula can carry a potential of a nerve damage or postoperative complications. However, there have been little studies about effective minimally invasive therapeutic method, yet. Our aim was to evaluate the efficacy and safety of ethanol ablation of ranulas and the clinicoradiologic factors that can predict outcome.MATERIALS AND METHODS:This retrospective study evaluated 23 patients with ranulas treated by percutaneous ethanol ablation. Treatment outcome was assessed in 20 patients followed for at least 6 months. The duration of symptoms before ethanol ablation, pretreatment volume, and parapharyngeal extension on sonography and/or CT were correlated with the outcome. The Mann-Whitney U test and Fisher exact test were used for comparison of the factors according to the outcome.RESULTS:The study evaluated 14 males and 9 females with a median age of 26 years (range, 3–41 years). Among 20 patients who were followed for at least 6 months (median, 20 months; range, 6–73 months), 9 patients (45%) demonstrated complete disappearance of the ranulas and 11 (55%) showed an incomplete response. When the patients were divided according to the duration of symptoms before ethanol ablation, the complete response rate was significantly higher in patients with ≤12 months of symptoms (73%, 8/11) than that in others (11%, 1/9) (P = .010). Pretreatment volume and parapharyngeal extension were not significantly different between the 2 groups.CONCLUSIONS:Ethanol ablation is a safe and noninvasive treatment technique for ranulas with a significantly better outcome in patients with ≤12 months of symptoms. Therefore, it could be considered an alternative nonsurgical approach for ranulas with recent onset of symptoms.

A ranula is a pseudocyst or mucous-retention cyst that arises from leakage of saliva from the sublingual or minor salivary gland.¹ Ranulas have traditionally been surgically treated by excision of the affected sublingual gland with or without the excision of the ranula.^1,2 Surgical excision is a definitive treatment with very low recurrence rates, ranging from 0% to 2%.^3,4 However, excision of the sublingual gland can be technically difficult and carries a potential risk of damage to the surrounding vital structures, including the lingual nerve and the submandibular duct, with postoperative complication rates ranging from 11% to 29%.^3,4 Therefore, there is a need for a nonsurgical minimally invasive treatment of ranulas.Among chemical ablation agents, picibanil (OK-432; Chugai Pharmaceutical Co, Tokyo, Japan) has been most commonly reported for minimally invasive treatment of ranulas.^1,3,5–9 Intracystic injection of OK-432 is safe without serious complications, but the recurrence rate is relatively high, from 23% to 48%.^1,3,8 Therefore, more effective sclerosing agents are necessary for successful minimally invasive treatment of ranulas.Ethanol is an effective sclerosing agent^2,10; its effects include instantaneous cellular dehydration and protein denaturation that result in the clumping of blood cells and vessel wall necrosis, followed by thrombosis and occlusion of vessels.^10,11 It has been reported that ethanol ablation (EA) is effective and safe for the treatment of benign cervical cystic lesions, including cystic thyroid nodules, thyroglossal duct cysts, and lymphatic malformations.^12–18To the best of our knowledge, no previous studies have examined the treatment efficacy and safety of EA for ranulas. The purpose of this study was to evaluate these features and the clinicoradiologic factors that can predict its outcome in a retrospective cohort.     

Symptom Differences and Pretreatment Asymptomatic Interval Affect Outcomes of Stenting for Intracranial Atherosclerotic Disease

BACKGROUND AND PURPOSE:Different types of symptomatic intracranial stenosis may respond differently to interventional therapy. We investigated symptomatic and pathophysiologic factors that may influence clinical outcomes of patients with intracranial atherosclerotic disease who were treated with stents.MATERIALS AND METHODS:A retrospective analysis was performed of patients treated with stents for intracranial atherosclerosis at 4 centers. Patient demographics and comorbidities, lesion features, treatment features, and preprocedural and postprocedural functional status were noted. χ² univariate and multivariate logistic regression analysis was performed to assess technical results and clinical outcomes.RESULTS:One hundred forty-two lesions in 131 patients were analyzed. Lesions causing hypoperfusion ischemic symptoms were associated with fewer strokes by last contact [χ² (1, n = 63) = 5.41, P = .019]. Nonhypoperfusion lesions causing symptoms during the 14 days before treatment had more strokes by last contact [χ² (1, n = 136), 4.21, P = .047]. Patients treated with stents designed for intracranial deployment were more likely to have had a stroke by last contact (OR, 4.63; P = .032), and patients treated with percutaneous balloon angioplasty in addition to deployment of a self-expanding stent were less likely to be stroke free at point of last contact (OR, 0.60; P = .034).CONCLUSIONS:More favorable outcomes may occur after stent placement for lesions causing hypoperfusion symptoms and when delaying stent placement 7–14 days after most recent symptoms for lesions suspected to cause embolic disease or perforator ischemia. Angioplasty performed in addition to self-expanding stent deployment may lead to worse outcomes, as may use of self-expanding stents rather than balloon-mounted stents.

Intracranial atherosclerotic disease (ICAD) causes considerable morbidity and mortality, accounting for up to one-third of ischemic strokes in some series, particularly in certain populations.^1–3 Some lesions prove recalcitrant to first-line medical management, and, in recent decades, endovascular treatments have emerged and evolved as complementary therapies.^4,5 Early series demonstrated technical feasibility and acceptable safety for percutaneous transluminal angioplasty (PTA) and then stent placement of lesions in ICAD.^5–17 Initially, intracranial procedures were performed with devices designed and approved for coronary interventions, with subsequent release of angioplasty balloons specifically engineered for intracranial use.^5,12,17–33 In 2005, the Wingspan stent system with Gateway PTA balloon catheter (Stryker, Kalamazoo, Michigan) became the first stent approved for treatment of ICAD in the United States.^{5,12,18–22,25,34} Numerous studies reported progressively improved outcomes and low complication rates, but randomized data proving efficacy were lacking.^{5,12,18,20,24,25,35,36} In 2011, enrollment in the first randomized, controlled trial to evaluate stent placement versus medical management of ICAD, the Stent placement and Aggressive Medical Management for Preventing Recurrent Stroke in Intracranial Stenosis (SAMMPRIS) trial, was halted early due to high complication rates in the stent placement group as compared with the medical management group.⁴The results of SAMMPRIS have elicited strong responses from both proponents and detractors of stent placement, with clinical decisions now changing.⁵ This current study retrospectively analyzes results of stent placement procedures performed for ICAD at 4 centers, with attention given to factors not specifically assessed in SAMMPRIS that may help guide further investigations of endovascular ICAD management.     

Immunoglobulin G4–Related Disease of the Orbit: Imaging Features in 27 Patients

BACKGROUND AND PURPOSE:Immunoglobulin G4–related disease is a systemic fibroinflammatory process of unknown etiology, characterized by tissue infiltration by immunoglobulin G4 plasma cells. The purpose of this study was to retrospectively identify the spectrum of imaging features seen in immunoglobulin G4–related disease of the orbit.MATERIALS AND METHODS:This study included 27 patients with biopsy-proved immunoglobulin G4–related disease of the orbit and either a CT or MR imaging of the orbits. These CT or MR imaging examinations were evaluated for the following: extraocular muscle size, extraocular muscle tendon enlargement, lacrimal gland enlargement, infiltrative process in the orbital fat (increased attenuation on CT or abnormal signal on MR imaging), infraorbital nerve enlargement, mucosal thickening in the paranasal sinuses, and extension of orbital findings intracranially.RESULTS:Extraocular muscles were enlarged in 24 of 27 (89%) patients, 21 (88%) bilaterally. In 32 of 45 (71%) affected orbits, the lateral rectus was the most enlarged muscle. In 26 (96%) patients, the tendons of the extraocular muscles were spared. Nineteen (70%) patients had lacrimal gland enlargement. Twelve (44%) patients had an infiltrative process within the orbital fat. Infraorbital nerve enlargement was seen in 8 (30%) patients. Twenty-four (89%) patients had sinus disease. Cavernous sinus or Meckel cave extension was seen in 3 (11%) patients.CONCLUSIONS:In patients with extraocular muscle enlargement, particularly when the tendons are spared and the lateral rectus is the most enlarged, and even more so when other noted findings are present, immunoglobulin G4–related disease should be a leading differential consideration, even over more commonly known etiologies of extraocular muscle enlargement.

Immunoglobulin G4 (IgG4)-related disease is a systemic inflammatory process of unknown etiology, characterized by tissue infiltration by IgG4 plasma cells and sclerosing inflammation.^1–5 Although initially described in association with autoimmune pancreatitis, manifestations of IgG4-related disease are now reported in nearly every organ system.^1–3,5–10Multiple case reports and small case series of orbital manifestations of IgG4-related disease have noted involvement of the extraocular muscles, lacrimal glands, and infraorbital nerve,^1,2,4,7–19 but these small series do not allow evaluation of the typical patterns of imaging findings in IgG4-related disease. The purpose of this study was to retrospectively identify the spectrum of imaging features seen in IgG4-related disease of the orbit. Ideally, these characteristics will help clinicians and radiologists recognize IgG4-related orbital disease among a broad differential of orbital pathologies.     

CT-guided injection of the anterior and middle scalene muscles: technique and complications

BACKGROUND AND PURPOSE:Anterior scalene block is a helpful diagnostic test for NTOS and a good predictor of surgical outcome. The purpose of this study was to describe the technique, success rate, and complications associated with CT-guided anesthetic and botulinum toxin injection of the ASM/MSM in patients with NTOS symptoms.MATERIALS AND METHODS:One hundred six participants (mean age, 41.5 ± 10 years; 80 women) were identified via a retrospective review of medical records for CT-guided scalene blocks. The procedure was evaluated regarding the technical success, defined as satisfactory detection of the ASM/MSM; intramuscular needle placement; intramuscular injection of contrast; appropriate delivery of medication; and frequency of unintended BP block or other complications. We also determined the outcome of patients who underwent surgery following the block.RESULTS:Study participants underwent 146 scalene injections, 83 blocks, and 63 chemodenervations, which were included in this investigation. In all cases, detection of the ASM/MSM and intramuscular needle placement was satisfactory. Postprocedural complications included 5 (3.4%) temporary BP blocks, 1 patient with (0.7%) Horner sign, 7 (4.8%) needle-induced pain reports, 1 (0.7%) case of dysphagia, and 2 (1.4%) instances of muscle weakness. There were no major complications reported. The rate of good outcome following surgery was the same in patients with positive versus negative blocks, 30/43 (70%) versus 5/7 (71%), respectively.CONCLUSIONS:CT guidance is a useful adjunct in performing accurate ASM/MSM blocks with a low rate of minor complications.

Estimates of TOS incidence vary widely, with rates ranging from 3 to 80 cases per 1000 people.^1,2 TOS is caused by compression of the neurovascular structures passing through the superior thoracic outlet, and it results from neck trauma (often from auto crashes), repetitive stress injury, congenital abnormalities (eg, cervical ribs), or a combinations of these.^3,4 There are 3 types of TOS: venous, arterial, and neurogenic. NTOS comprises almost 95% of TOS cases^5–7 and is mostly seen in the third and fourth decades of life, with a female/male ratio of 3:5–4:1.^2,6–8 Symptoms of NTOS include paresthesias; pain on the affected side of the neck, shoulder, or arm; discoloration and cold intolerance of fingers in cases involving sympathetic fibers; and, less commonly, weakness of the upper extremity. Venous TOS commonly presents with acute effort thrombosis of the subclavian vein, also known as Paget-Schroetter syndrome.^2,6 Patients usually are athletes who present with an acutely swollen discolored upper extremity; pain due to subclavian vein obstruction, with or without thrombosis; and visible subcutaneous veins over the involved shoulder and chest wall.^2,3,5,6 Arterial TOS is associated with hand ischemia caused by either external compression of the subclavian artery or from emboli arising from a subclavian artery aneurysm.^3,5,6 The symptoms of arterial TOS include digital ischemia, claudication, pallor, coldness, paresthesia, and pain in the hand but seldom in the shoulder or neck. Occasionally, the neurologic and vascular components may coexist in the same patient.²If ergonomic modifications, exercise, and physiotherapy do not improve the symptoms, anesthetic injection of the anterior scalene muscle, as a diagnostic test, is often performed.⁹ The anesthetic injection allows the first rib to descend by relaxing the scalene muscle and thereby decompressing the BP.^6,9–11 The anterior scalene block has been the most helpful test to confirm the diagnosis of NTOS^5,6,11–15 and to predict the response to surgery, because it may mimic the results of first-rib resection and anterior scalenectomy.^{6,10–12,14,16} However, to be predictive, the injection should avoid anesthesia of the BP and sympathetic chain, and the patient should be both medically and psychologically stable.¹³Different methods have been used to guide the scalene injection, including the use of anatomic landmarks,^13,17 EMG,¹² sonography,¹¹ combinations of EMG and sonography,¹⁸ EMG and fluoroscopy,¹⁸ and CT most recently.^9,10CT-guided injection of the scalene muscle is a novel technique,⁹ which has not been previously evaluated in the radiology literature, to our knowledge. The purpose of this study was to describe the technique, findings, and complications associated with CT-guided injection of the ASM/MSM in patients being evaluated or treated for NTOS. We also assessed the predictive value of the CT-guided scalene block by determining the outcome of patients who underwent surgical decompression following the block.     

Cortical Activation Through Passive-Motion Functional MRI

BACKGROUND AND PURPOSE:Functional brain mapping is an important technique for neurosurgical planning, particularly for patients with tumors or epilepsy; however, mapping has traditionally involved invasive techniques. Existing noninvasive techniques require patient compliance and may not be suitable for young children. We performed a retrospective review of our experience with passive-motion functional MR imaging in anesthetized patients to determine the diagnostic yield of this technique.MATERIALS AND METHODS:A retrospective review of patients undergoing passive-motion fMRI under general anesthesia at a single institution over a 2.5-year period was performed. Clinical records were evaluated to determine the indication for fMRI, the ability to detect cortical activation, and, if present, the location of cortical activation.RESULTS:We identified 62 studies in 56 patients in this time period. The most common indication for fMRI was epilepsy/seizures. Passive-motion fMRI identified upper-extremity cortical activation in 105 of 119 (88%) limbs evaluated, of which 90 (86%) activations were in an orthotopic location. Lower-extremity cortical activation was identified in 86 of 118 (73%) limbs evaluated, of which 73 (85%) activations were in an orthotopic location.CONCLUSIONS:Passive-motion fMRI was successful in identifying cortical activation in most of the patients. This tool can be implemented easily and can aid in surgical planning for children with tumors or candidates for epilepsy surgery, particularly those who may be too young to comply with existing noninvasive functional measures.

The criterion standard for presurgical brain mapping has typically been intraoperative cortical stimulation mapping and the Wada test.^1–4 Both methods are invasive procedures, and their efficacy and superiority over other mapping procedures have become less clear with advances in noninvasive brain-mapping techniques,^4–12 with some studies showing that these alternative methods are comparable to stand-alone and/or adjunct techniques.^9–18 Blood oxygen level–dependent functional MR imaging is an increasingly used imaging technique in the clinical setting. Since the early 1990s, it has been used to study brain function in healthy individuals and particularly for surgical planning in patients with brain tumors or epilepsy.^{2,4,17,19–22} This imaging technique maps areas of cortical activation via changes in blood flow to metabolically active brain regions during cortical activation, typically secondary to specific motor, language, and visual tasks. fMRI provides a number of benefits: it is noninvasive, it is a useful tool for presurgical evaluation for invasive procedures that involve high risk,^{2,4,17,19,20,23,24} and it can also assess the current function of patients with brain lesions or previous brain surgery.^20,25 Clinically, it is performed as a task-based technique that requires the patient to cooperate and keep all other body movements to a minimum. Incomplete compliance limits the utility of this technology and introduces risk for spurious results. Compliance with the tasks and remaining still is a particular concern in young children and patients with developmental or acquired cognitive deficits.^26,27 Even children who can perform the task during training sessions may not be able to comply in the MR imaging scanner.²⁷A strategy that allows this information to be obtained from subjects who are unable to cooperate is to perform a similar fMRI task under sedation. fMRI of sedated patients performed with passive motion of the extremities has been successful in some reports.^{15,23,24,28,29} The goal is to map the motor cortex while removing the need for task compliance and reducing or eliminating concerns for patient motion.^23,24,28 We performed a retrospective review of our institution''s 2.5-year experience with passive-motion fMRI to assess the feasibility and reliability of this imaging technique.     

High-Resolution MRI of the Intraparotid Facial Nerve Based on a Microsurface Coil and a 3D Reversed Fast Imaging with Steady-State Precession DWI Sequence at 3T

BACKGROUND AND PURPOSE:3D high-resolution MR imaging can provide reliable information for defining the exact relationships between the intraparotid facial nerve and adjacent structures. The purpose of this study was to explore the clinical value of using a surface coil combined with a 3D-PSIF-DWI sequence in intraparotid facial nerve imaging.MATERIALS AND METHODS:Twenty-one healthy volunteers underwent intraparotid facial nerve scanning at 3T by using the 3D-PSIF-DWI sequence with both the surface coil and the head coil. Source images were processed with MIP and MPR to better delineate the intraparotid facial nerve and its branches. In addition, the SIR of the facial nerve and parotid gland was calculated. The number of facial nerve branches displayed by these 2 methods was calculated and compared.RESULTS:The display rates of the main trunk, divisions (cervicofacial, temporofacial), and secondary branches of the intraparotid facial nerve were 100%, 97.6%, and 51.4% by head coil and 100%, 100%, and 83.8% by surface coil, respectively. The display rate of secondary branches of the intraparotid facial nerve by these 2 methods was significantly different (P < .05). The SIRs of the intraparotid facial nerve/parotid gland in these 2 methods were significantly different (P < .05) at 1.37 ± 1.06 and 1.89 ± 0.87, respectively.CONCLUSIONS:The 3D-PSIF-DWI sequence combined with a surface coil can better delineate the intraparotid facial nerve and its divisions than when it is combined with a head coil, providing better image contrast and resolution. The proposed protocol offers a potentially useful noninvasive imaging sequence for intraparotid facial nerve imaging at 3T.

3D high-resolution MR imaging can provide reliable information for depicting normal intraparotid facial nerve anatomy and defining the exact relationship of the intraparotid facial nerve and adjacent structures; this information could assist in the planning of parotid tumor surgery.¹ Imaging the intraparotid course of the facial nerve is a challenge due to the fine structure and complex anatomy of the nerve.^1–4 With recent advances in MR imaging technology, especially the use of surface coils combined with 3D high-resolution MR imaging technology, increased attention has been directed to intraparotid facial nerve imaging.^1–4 The inherent resolution of a surface coil itself is significantly better than that of a head coil, ensuring high-quality imaging for fine structures, particularly in superficial organs such as the parotid gland or eye.^1,5 Recently, 3D high-resolution sequences such as 3D gradient-recalled acquisition in the steady state sequence and 3D FIESTA have been applied to intraparotid facial nerve imaging.^2–4 These sequences rely mainly on the fat within the parotid gland as a high signal background to show the facial nerve because both the intraparotid facial nerve and the parotid duct are visualized as linear structures of low intensity.^2–4 In another report, the intraparotid facial nerve showed low signal compared with the high intensity of the parotid duct by using a balanced turbo-field echo, thus avoiding confusion between these 2 structures; however, no volumetric images were obtained,⁶ and MPR or curved planar reconstruction was not available. Thus, although there are several MR imaging sequences that can delineate the intraparotid facial nerve and parotid duct, limitations remain. The aim of this study was to explore the capabilities of simultaneously displaying the intraparotid facial nerve and parotid duct by using a surface coil combined with 3D-PSIF-DWI on a 3T MR imaging scanner.     

Cranial Nerve Abnormalities in Oculo-Auriculo-Vertebral Spectrum

BACKGROUND AND PURPOSE:Cranial nerve abnormalities might be observed in hemifacial microsomia and microtia (oculo-auriculo-vertebral spectrum), but the rate, features, and relationship with functional impairment or phenotype severity have not yet been defined. This study aimed at investigating absence/asymmetry, abnormal origin, morphology and course of cranial nerves, and presence/asymmetry of the foramen ovale and inferior alveolar nerve canal in a cohort of oculo-auriculo-vertebral spectrum patients.MATERIALS AND METHODS:Twenty-nine patients with oculo-auriculo-vertebral spectrum (mean age, 7 years; age range, 0.2–31 years; 12 females) underwent brain MR imaging, CT, and neurologic evaluation; 19 patients had a more severe phenotype (Goldenhar syndrome).RESULTS:Cranial nerve abnormalities were detected only in patients with Goldenhar syndrome (17/19, bilaterally in 8) and were involved the second (4/19), third (1/18), fifth (11/19), sixth (8/16), seventh (11/18), and eighth (8/18) cranial nerves. Multiple cranial nerve abnormalities were common (11/17). Eleven patients showed bone foramina abnormalities. Trigeminal and facial nerve dysfunctions were common (44% and 58%, respectively), especially in patients with Goldenhar syndrome. Trigeminal abnormalities showed a good correlation with ipsilateral dysfunction (P = .018), which further increased when bone foramina abnormalities were included. The facial nerve showed a trend toward correlation with ipsilateral dysfunction (P = .081). Diplopia was found only in patients with Goldenhar syndrome and was associated with third and sixth cranial nerve abnormalities (P = .006).CONCLUSIONS:Among patients with oculo-auriculo-vertebral spectrum, cranial nerve morphologic abnormalities are common, correlate with phenotype severity, and often entail a functional impairment. The spectrum of cranial nerve abnormalities appears wider than simple hypo-/aplasia and includes an anomalous cisternal course and partial/complete fusion of diverse cranial nerves.

Oculo-auriculo-vertebral spectrum (OAVS) (Online Mendelian Inheritance in Man, 164210)¹ is a rare heterogeneous congenital condition (incidence, 1:3500–5600 live births; male/female ratio, 3:2),^2–4 in which the head structures originating from the first and second pharyngeal arches are incompletely developed on 1 (85% of cases) or both sides.^3,5 The disease mostly results in ear (microtia) and jaw (hemifacial microsomia) abnormalities (On-line Fig 1). Nonetheless, the abnormality spectrum might be fairly wide, from mild external and medium ear involvement or isolated facial asymmetry to anotia with complex facial deformity. The most severe cases also present with eye or spine involvement and are known as Goldenhar syndrome from the French ophthalmologist who first described the syndrome in 1952.⁶ Familial history suggestive of both autosomal recessive and dominant inheritance has been reported, and genes on chromosomes 5, 12, 14, and 22 have been implicated.^7–10 However, most cases of OAVS are sporadic and without a known etiology. Abnormal embryonic vascular supply,¹¹ hematomas, and drug use during the early phases of gestation have been reported to cause the disruption of mesodermal migration, leading to defective formation of bone and soft-tissue structures.¹²Most interesting, a few case reports and small series studies have shown a concomitant impairment of cranial nerves (CNs),^13–26 highlighting the possible involvement of neural structures in OAVS and addressing its potentially relevant clinical impact. To date, the underlying anatomic and structural CN abnormalities have been poorly investigated because the available data rely on anecdotal postmortem examination¹⁷ or neuroimaging findings.¹⁹ Additionally, the overall frequency of CN abnormalities, their association with CN dysfunction, and the relationship with the OAVS phenotype severity have not yet been defined, to our knowledge.In the past few years, MR imaging has become a powerful tool for investigating in vivo the cisternal segment of the CNs. With routinely available 1.5T MR imaging scanners and dedicated high-resolution sequences, it is possible to verify the presence and characterize the morphology, diameter, and cisternal course of most CNs. CN MR imaging evaluation has, therefore, become helpful for diagnosing several conditions such as Kallmann syndrome, optic neuritis, septo-optic dysplasia, neurovascular conflicts, and so forth. Moreover, the evaluation of the intrameatal branches of CN VIII is included in the diagnostic work-up of implant planning in patients with congenital profound hearing loss. Besides, because skull base foramina and bone canal development is induced by the presence of the corresponding CN branch,²⁷ CN abnormalities might be also indirectly inferred by bone CT. Absence or hypoplasia/stenosis of the facial canal, internal acoustic canal, foramina ovalia and rotundum, hypoglossal canal, or inferior alveolar canal might indicate hypoplasia or aplasia of the relative nerves and branches.Therefore, MR imaging and CT might help to detect or raise the suspicion of morphologic CN abnormalities providing relevant information, especially when the CN impairment is difficult to evaluate due to early age, concomitant facial bone and soft-tissue asymmetry, or poor compliance of patients with OAVS.The present study aims at investigating, in patients with OAVS, the rate of CN abnormalities, the type (eg, agenesia, hypoplasia, abnormal origin, or cisternal course), the association with functional impairment, and the side of hemifacial microsomia as well as the relationship with the phenotype severity.