中耳胆脂瘤--一个特征性CT征象

目的 :研究中耳胆脂瘤的 CT特征 ,提高对其 CT征象的认识。方法 :对手术证实的 14例慢性中耳炎和 14例中耳胆脂瘤的病人进行 HRCT扫描 ,着重观察盾板和上鼓室外侧壁骨质改变。对软组织病灶分布、形态 ,听骨破坏等也进行了分析、比较。结果 :胆脂瘤中 ,盾板破坏 12例 ,同时合并上鼓室外侧壁破坏 8例 ;慢性中耳炎肉芽肿型盾板侵蚀 1例 ,无上鼓室外侧壁破坏。结论 :盾板骨质破坏和上鼓室外侧壁破坏是松弛部胆脂瘤较特征性的 CT征象。软组织分布和形态、听骨破坏有辅助诊断价值。     

Optimal Duration of MRI Follow-up to Safely Identify Middle Ear Residual Cholesteatoma

BACKGROUND AND PURPOSE:Previous studies have demonstrated the usefulness of non-EPI DWI for detection of residual cholesteatoma. However, limited data are available to determine the suitable duration of imaging follow-up after a first MR imaging with normal findings has been obtained. The present study aimed to determine the optimal duration of non-EPI DWI follow-up for residual cholesteatoma.MATERIALS AND METHODS:A retrospective, monocentric study was performed between 2013 and 2019 and included all participants followed up after canal wall up tympanoplasty with at least 2 non-EPI DWI examinations performed on the same 1.5T MR imaging scanner. MR images were reviewed independently by 2 radiologists. Sensitivity and specificity values were calculated as a function of time after the operation. Receiver operating characteristic curves were analyzed to determine the optimal follow-up duration.RESULTS:We analyzed 47 MRIs from 17 participants. At the end of the individual follow-up period, a residual cholesteatoma had been found in 41.1% of cases. The follow-up duration ranged from 20 to 198 months (mean, 65.9 [SD, 43.9] months). Participants underwent between 2 and 5 non-EPI DWI examinations. Analyses of the receiver operating characteristic curves revealed that the optimal diagnostic value of non-EPI DWI occurred 56 months after the operation when the first MR imaging performed a mean of 17.3 (SD, 6.8) months after the operation had normal findings (sensitivity = 0.71; specificity = 0.7, Youden index = 0.43).CONCLUSIONS:Repeat non-EPI DWI is required to detect slow-growing middle ear residual cholesteatomas. We, therefore, recommend performing non-EPI DWI for at least the first 5 years after the initial operation.

The development of DWI has profoundly changed the management of middle ear cholesteatomas. An increasing number of surgeons no longer systematically perform second-look surgery, and MR imaging follow-up is performed if revision surgery is not needed to treat conductive hearing loss. Numerous studies have evaluated the sensitivity and specificity of EPI DWI and non-EPI DWI sequences for the detection of residual cholesteatoma. Non-EPI DWI sequences offer the best sensitivity and specificity and are suitable for the detection of residual cholesteatomas as small as 2 mm.¹ A recent meta-analysis of 26 studies concerning non-EPI DWI showed a pooled sensitivity and specificity of 0.91 (95% CI, 0.87–0.95) and 0.92 (95% CI, 0.86–0.96), respectively.¹ Another meta-analysis reported a similar pooled sensitivity and specificity of 0.89 (95% CI, 0.52–0.99) and 0.93 (95% CI, 0.81–0.98), respectively.²However, data on the diagnostic value of non-EPI DWI sequences regarding the optimal timing after the initial operation remain limited. Lingam et al³ reported a sensitivity of 0.91 (95% CI, 0.79–0.97) and a specificity of 0.88 (95% CI, 0.69–0.97) with a median time to MR imaging of 5.4 months after the operation. Khemani et al⁴ found a sensitivity of 0.82 (95% CI, 0.63–0.94) and a specificity of 0.90 (95% CI, 0.55–1.00) when MR imaging was performed 10–24 months after the operation.Most authors agree that imaging follow-up should not start <12 months postsurgery,^5-8 to reduce the number of false-negatives due to residual cholesteatomas measuring <2 mm.⁹ Nevertheless, the optimal duration of follow-up necessary to exclude the existence of a residual cholesteatoma if the findings of the first MR imaging are considered normal is unclear. In a recent retrospective series, follow-up non-EPI DWI detected residual cholesteatoma in 12 of 88 patients only after a mean interval of 3.8 years after the initial cholesteatoma surgery (median, 3.7 years; range, 1.6–7.9 years).¹⁰ Pai et al¹⁰ suggested that imaging follow-up should be performed for a minimum of 5 years postoperatively, without defining how this was calculated.To provide more information on the optimal imaging follow-up duration, we describe the long-term follow-up imaging of participants with ≥2 non-EPI DWI examinations for residual middle ear cholesteatoma. The sensitivity and specificity values were calculated as a function of the duration of the follow-up, and the receiver operating characteristic curves were analyzed to determine the optimal follow-up time.     

Tympanic Plate Fractures in Temporal Bone Trauma: Prevalence and Associated Injuries

BACKGROUND AND PURPOSE:The prevalence of tympanic plate fractures, which are associated with an increased risk of external auditory canal stenosis following temporal bone trauma, is unknown. A review of posttraumatic high-resolution CT temporal bone examinations was performed to determine the prevalence of tympanic plate fractures and to identify any associated temporal bone injuries.MATERIALS AND METHODS:A retrospective review was performed to evaluate patients with head trauma who underwent emergent high-resolution CT examinations of the temporal bone from July 2006 to March 2012. Fractures were identified and assessed for orientation; involvement of the tympanic plate, scutum, bony labyrinth, facial nerve canal, and temporomandibular joint; and ossicular chain disruption.RESULTS:Thirty-nine patients (41.3 ± 17.2 years of age) had a total of 46 temporal bone fractures (7 bilateral). Tympanic plate fractures were identified in 27 (58.7%) of these 46 fractures. Ossicular disruption occurred in 17 (37.0%). Fractures involving the scutum occurred in 25 (54.4%). None of the 46 fractured temporal bones had a mandibular condyle dislocation or fracture. Of the 27 cases of tympanic plate fractures, 14 (51.8%) had ossicular disruption (P = .016) and 18 (66.6%) had a fracture of the scutum (P = .044). Temporomandibular joint gas was seen in 15 (33%) but was not statistically associated with tympanic plate fracture (P = .21).CONCLUSIONS:Tympanic plate fractures are commonly seen on high-resolution CT performed for evaluation of temporal bone trauma. It is important to recognize these fractures to avoid the preventable complication of external auditory canal stenosis and the potential for conductive hearing loss due to a fracture involving the scutum or ossicular chain.

There are many reports in the literature describing CT of temporal bone trauma,^1–4 detailing fracture plane orientations,^4–6 ossicular disruptions, otic capsule involvement,^4,5 associations with air in the temporomandibular joint (TMJ),⁷ facial nerve injury,^4–6 and fracture mimics, to name a few broad categories.⁸ Temporal bone fractures involving the tympanic plate (Figs 1 and ​and2),2), however, are under-recognized and have received little attention beyond isolated case reports involving mandibular trauma.^8–15 The tympanic plate of the temporal bone is a U-shaped structure forming the anterior wall, floor, and part of the posterior wall of the external auditory canal. The limited literature concerning tympanic plate fracture (TPF) suggests that these types of fractures are uncommon.^4,10,11,16 Most literature on direct and indirect CT findings of temporal bone trauma was published in the pre-/early multidetector CT era^1,3,7,17,18 or was based solely on non-high-resolution CT (HRCT) imaging,¹⁹; however, it is possible that posttraumatic TPFs are under-recognized or overlooked by the inexperienced observer. TPFs are important to identify, given the potential for the clinically significant long-term complications of external auditory canal stenosis and trismus.²⁰ The purpose of this study was to retrospectively review acute posttraumatic HRCT temporal bone studies to determine the true incidence of TPF and to identify other associated temporal bone injuries.Open in a separate windowFig 1.External sagittal view of the left temporal bone depicting the tympanic plate as it forms part of the anterior wall of the external auditory canal.Open in a separate windowFig 2.Oblique 3D view of the skull, including the external portion of the left temporal bone and the Pöschl plane for CT reformatting superimposed. This Pöschl plane view is depicted in the inset along with a TPF and some of the possible associated traumatic injuries.     

CT Findings in the External Auditory Canal after Transcanal Surgery

BACKGROUND AND PURPOSE:Middle ear surgery is often performed through the external auditory canal, and the CT appearance of the external auditory canal after transcanal middle ear surgery can mimic erosive pathology such as carcinoma, external auditory canal cholesteatoma, or necrotizing external otitis. We reviewed the CT findings in a group of patients following transcanal surgery to highlight this potential pitfall in interpretation.MATERIALS AND METHODS:Twenty-seven temporal bones in 25 patients with a history of a transcanal approach to the middle ear and available postoperative CT imaging were identified. Images were assessed for changes along or involving the walls of the external auditory canal, including widening, irregularity, bony defects, and soft tissue opacification.RESULTS:Osseous changes along the floor of the external auditory canal were demonstrated in 25 of 27 (92.6%) temporal bone CT scans. Similar changes were present in the superior and anterior walls of the external auditory canal in 21 and 18 temporal bones, respectively. The anterior wall was the most common site for complete bony defects (10 of 27 temporal bones). The posterior wall was the least often involved, with osseous changes in 15 of 27 temporal bones and bony defects in 3 cases. Soft tissue thickening was seen most commonly along the floor. No patient was found to have a superimposed pathologic process of the external auditory canal.CONCLUSIONS:CT findings in the external auditory canal after transcanal surgery include thinning, irregularity and/or flattening of the bone, soft tissue thickening, and bony wall defects. Although these changes may be subtle, they may mimic pathology and should be included in the differential diagnosis of osseous abnormality of the external auditory canal.

Middle ear surgery performed through the external auditory canal (EAC) often involves drilling a portion of the bony canal wall to provide access and necessary exposure.^1–3 In the absence of associated transmastoid surgery (such as a canal wall down mastoidectomy), the postoperative status may not be immediately obvious to the interpreting radiologist, and relevant history may not be provided. On CT, such postoperative changes in the external canal can mimic bony and soft tissue changes typically associated with neoplasms, external canal cholesteatoma, or aggressive infections of the EAC. Prior literature has predominantly focused on the appearance of the middle ear after surgery.^4–11 We describe the CT appearance of the EAC after transcanal surgery so that postoperative change can be included in the differential diagnosis, even in the absence of available history, and erroneous diagnoses may be avoided.     

Comparison of Readout-Segmented Echo-Planar Imaging and Single-Shot TSE DWI for Cholesteatoma Diagnostics

BACKGROUND AND PURPOSE:The high diagnostic value of DWI for cholesteatoma diagnostics is undisputed. This study compares the diagnostic value of readout-segmented echo-planar DWI and single-shot TSE DWI for cholesteatoma diagnostics.MATERIALS AND METHODS:Thirty patients with newly suspected cholesteatoma were examined with a dedicated protocol, including readout-segmented echo-planar DWI and single-shot TSE DWI at 1.5T. Acquisition parameters of both diffusion-weighted sequences were as follows: b=1000 s/mm,² axial and coronal section orientations, and section thickness of 3 mm. Image quality was evaluated by 2 readers on a 5-point Likert scale with respect to lesion conspicuity, the presence of susceptibility artifacts mimicking cholesteatomas, and overall subjective image quality. Sensitivity and specificity were calculated using histology results as the gold standard.RESULTS:Twenty-five cases of histologically confirmed cholesteatomas were included in the study group. Lesion conspicuity was higher and fewer artifacts were found when using TSE DWI (both P < .001). The overall subjective image quality, however, was better with readout-segmented DWI. For TSE DWI, the sensitivity for readers 1 and 2 was 92% (95% CI, 74%–99%) and 88% (95% CI, 69%–97%), respectively, while the specificity for both readers was 80% (95% CI, 28%–99%). For readout-segmented DWI, the sensitivity for readers 1 and 2 was 76% (95% CI, 55%–91%) and 68% (95% CI, 46%–85%), while the specificity for both readers was 60% (95% CI, 15%–95%).CONCLUSIONS:The use of TSE DWI is advisable for cholesteatoma diagnostics and preferable over readout-segmented DWI.

Cholesteatoma is a common non-neoplastic disease in otology, characterized by collections of trapped keratinous debris within a sack of stratified epithelium, typically found in the middle ear and capable of causing a progressive inflammatory process.¹ Clinical complications include the destruction of adjacent bone and ossicular structures, which can lead to conductive or sensoneuronal hearing loss.^2,3 Cholesteatoma is commonly treated with surgery, ranging from focal excision to radical mastoidectomy.⁴ A second-look surgery procedure is typically performed within the first 2 years after the initial surgery to identify residual or recurrent cholesteatoma foci. Unlike canal wall down mastoidectomy, visual inspection of canal wall up mastoidectomy can be challenging; hence, a reliable diagnostic imaging tool is desirable for accurate follow-up diagnosis and treatment.^5–7 Preoperative high-resolution CT is the method of choice for the detection of osseous disintegration and is sufficient for diagnosis; however, for recurrent cholesteatoma after surgery, its role may be more limited.⁸ MR imaging is suitable for the assessment pre- and postsurgery using DWI and delayed postcontrast T1-weighted spin-echo imaging, which enable differentiation between keratinous debris and noncholesteatoma findings such as granulation tissue or scar.⁹The value of DWI in cholesteatoma diagnostics was initially shown using echo-planar DWI sequences.^10-12 Alternative approaches have been proposed for cholesteatoma diagnostics such as diffusion-sensitized driven-equilibrium DWI¹³ and PROPELLER TSE DWI (tseDWI).¹⁴ Notably, tseDWI techniques introduce radiofrequency refocusing pulses between the k-space lines and are, therefore, not able to easily fulfill the Carr-Purcell-Meibom-Gill Sequence condition if diffusion encoding is applied—an issue that must be addressed in the sequence design and essentially often degrades the image quality.¹⁵ Nonetheless, several studies have suggested single-shot tseDWI to be superior in terms of diagnostic accuracy compared with single-shot echo-planar DWI.^16-18 The image quality of EPI in the temporal region is often degraded due to the inhomogeneous magnetic environment at the skull base. Moreover, regions adjacent to bone- or air-filled spaces can artificially appear hyperintense, which can be misleading and result in false-positive findings.Readout-segmented echo-planar DWI (rsDWI)¹⁹ as a derivative of conventional echo-planar DWI can be used to minimize the geometric distortions to improve both image quality and diagnostic accuracy.^20,21 In a recently published work by Algin et al,²¹ rsDWI proved to be superior to single-shot EPI sequences for cholesteatoma diagnostics. Hence, this study sought to compare rsDWI and tseDWI, focusing on image quality and performance in cholesteatoma diagnostics.     

Prevalence of Internal Auditory Canal Diverticulum and Its Association with Hearing Loss and Otosclerosis

BACKGROUND AND PURPOSE:Focal low-attenuation outpouching or diverticulum at the anterolateral internal auditory canal is an uncommon finding on CT of the temporal bone. This finding has been described as cavitary otosclerosis in small case reports and histology series. The purpose of this study was to establish the prevalence of internal auditory canal diverticulum and its association with classic imaging findings of otosclerosis and/or hearing loss.MATERIALS AND METHODS:Temporal bone CT scans of 807 patients, obtained between January 2013 and January 2016, were retrospectively reviewed to identify internal auditory canal diverticula and/or classic imaging findings of otosclerosis. Clinical evaluations for hearing loss were reviewed for patients with internal auditory canal diverticula and/or otosclerosis.RESULTS:Internal auditory canal diverticula were found in 43 patients (5%); classic otosclerosis, in 39 patients (5%); and both findings, in 7 patients (1%). Most temporal bones with only findings of internal auditory canal diverticula (91%) demonstrated hearing loss, with 63% of this group demonstrating sensorineural hearing loss. The hearing loss classification distribution was significantly different (P < .01) from that in the classic otosclerosis group and in the group with both diverticula and otosclerosis.CONCLUSIONS:Internal auditory canal diverticula are not uncommon on CT examinations of the temporal bone and most commonly occur without classic imaging findings of otosclerosis. These lesions are associated with sensorineural hearing loss, and referral for hearing evaluation may be appropriate when present.

A focal low-attenuation notch or diverticulum within the temporal bone continuous with the internal auditory canal (IAC) is an unusual finding on imaging studies of the temporal bone. Several histologic and imaging case reports refer to this finding as a form of cavitary otosclerosis^1–4 and even suggest that the presence is associated with advanced disease.³Otosclerosis is an osteodystrophic disorder of the otic capsule, resulting in abnormal resorption of endochondral bone and deposition of abnormal vascular bone. Otosclerosis usually appears in the third-to-fifth decades of life, and most commonly affects women. Clinical otosclerosis is present in <1% of the population, though it has been reported in up to 11% of the population on histology performed at postmortem examination.⁵ On CT of the temporal bone, otosclerosis commonly appears as lucent or hypodense bone surrounding the otic capsule, often limited to the region anterior to the oval window. This process results in either conductive hearing loss (CHL) due to fixation of the stapes footplate or mixed conductive and sensorineural hearing loss (SNHL) due concomitant otic capsule involvement. Otosclerosis presenting with only SNHL in the absence of CHL is rare and is often called “cochlear otosclerosis.”^5–9Establishing the significance of the IAC diverticulum or notch is important for both the radiologist and referring physician in guiding clinical management. Determining the relationship of this lesion to classic imaging findings of otosclerosis could also be helpful in the understanding of otosclerosis and the spectrum of clinical presentations. Therefore, the purpose of this study was the following: 1) to determine the prevalence of IAC diverticula at our institution, and 2) to explore potential associations with otosclerosis and hearing loss in patients identified with an IAC diverticulum.     

Correlation of Prenatal and Postnatal MRI Findings in Schizencephaly

BACKGROUND AND PURPOSE:Schizencephaly is a rare malformation of the brain characterized by a gray matter–lined defect extending from the pial surface to the lateral ventricles. The purpose of this study was to correlate imaging findings of schizencephaly and associated anomalies on fetal and postnatal MR imaging and assess possible changes that may occur from the prenatal-to-postnatal state.MATERIALS AND METHODS:A retrospective review of subjects with schizencephaly who had both pre- and postnatal MR imaging was performed. Subject age, cleft type, number, location, and features of the defects and associated anomalies were recorded. Normalized dimensions of the defect and ipsilateral ventricle were measured and correlated to changes in the clefts between pre- and postnatal imaging.RESULTS:Ten subjects with 18 clefts (8 bilateral) were included. Most defects (83%) were open on prenatal MR imaging, but 47% of those were found to have subsequently closed on postnatal imaging. Evidence of prior hemorrhage was seen in 83%. Prenatal MR imaging detected all cases of an absent septum pellucidum but detected a fraction of gross polymicrogyria and missed all cases of optic nerve hypoplasia. The normalized ipsilateral ventricular and inner and middle width dimensions of the defects were significantly decreased at postnatal imaging (P < .05). The widths of the defects, ventricular width, and presence of hemorrhage were not predictors of closure of prenatally diagnosed open defects (P > .05).CONCLUSIONS:In our series, nearly half of prenatally open schizencephaly defects had closed on postnatal imaging. Prenatal MR imaging was only able to demonstrate some of the associated anomalies.

Schizencephaly is a rare malformation of the central nervous system characterized by a gray matter–lined defect extending from the pial surface to the lateral ventricles. The etiology of schizencephaly is poorly understood; however, it appears to be heterogeneous.^1–3 The presence of gray matter lining the defects, distinguishing schizencephaly from porencephaly, is usually ascribed to the damage to the radial glial cell fibers or to the molecules that promote neuronal migration and timing during pregnancy.^2,4 Despite early reports of the association of schizencephaly and mutations of the EMX2 homeobox gene,⁵ this association has not been verified in further studies.⁶ The common pathophysiology of injury is frequently ascribed to a vascular disruption, hypoxia-ischemia, and/or prenatal infection at critical time points during neuronal development,^1–3 though there are some reports favoring schizencephaly as a developmental disorder.^7–9Classically, schizencephaly has been divided into “closed” or “closed-lip” defects, in which the walls appose one another within the defect, and “open” or “open-lip” defects, in which CSF fills the defect all the way from the lateral ventricle to the overlying subarachnoid space.¹⁰ Open lesions have been further subclassified as small or large according to size of the defect.¹⁰ These classifications have prognostic significance because it has been shown that a small, unilateral closed defect without involvement of the motor cortex can be associated with seizures but otherwise normal development.¹⁰ The prognosis is poorer with open and bilateral defects.^2,10,11 Associated anomalies, such as optic nerve hypoplasia, absence of the septum pellucidum, and other migrational abnormalities, will also adversely affect the prognosis.^2,9,12,13MR imaging was reported to prenatally diagnose schizencephaly as early as 1989.¹⁴ On the basis of the current literature, the imaging appearance of schizencephaly on fetal MR imaging is considered identical to that in postnatal MR imaging.² The purpose of this study was to correlate imaging findings of schizencephaly and associated anomalies on fetal and postnatal MR imaging and to assess the possible changes that may occur from the prenatal-to-postnatal state on MR imaging.     

Use of Non-Echo-Planar Diffusion-Weighted MR Imaging for the Detection of Cholesteatomas in High-Risk Tympanic Retraction Pockets

BACKGROUND AND PURPOSE:Non-echo-planar DWI MR imaging (including the HASTE sequence) has been shown to be highly sensitive and specific for large cholesteatomas. The purpose of this study was to determine the diagnostic accuracy of HASTE DWI for the detection of incipient cholesteatoma in high-risk retraction pockets.MATERIALS AND METHODS:This was a prospective study of 16 patients who underwent MR imaging with HASTE DWI before surgery. Surgeons were not informed of the results, and intraoperative findings were compared against the radiologic diagnosis. Sensitivity, specificity, and positive and negative predictive values were calculated.RESULTS:Among the 16 retraction pockets, 10 cholesteatomas were diagnosed intraoperatively (62.5%). HASTE showed 90% sensitivity, 100% specificity, 100% positive predictive value, and 85.7% negative predictive value in this group of patients. We found only 1 false-negative finding in an infected cholesteatoma.CONCLUSIONS:We demonstrate a high correlation between HASTE and surgical findings, suggesting that this technique could be useful for the early detection of primary acquired cholesteatomas arising from retraction pockets and could help to avoid unnecessary surgery.

Middle ear cholesteatomas are benign but locally aggressive nonneoplastic lesions composed of a keratinizing stratified squamous epithelial matrix, an inflammatory perimatrix, and desquamated keratin content.¹ Pathophysiologically, cholesteatomas are divided into congenital (epithelium trapped within the middle ear during fetal development) and acquired. Acquired cholesteatomas are further divided into primary (arising from a tympanic membrane retraction) and secondary (epithelium reaching the middle ear through a tympanic perforation, fracture, or iatrogenic procedure).^2,3 Cholesteatomas progressively erode the bony structures surrounding the middle ear (ossicles, facial nerve canal, bony labyrinth, and skull base), predisposing to a wide range of complications, including potentially severe infections such as meningitis and intracranial abscesses.⁴ Surgery is the only known curative treatment and should be performed early because less destruction allows more conservative and hearing-preserving procedures with a reduced risk of complications.Tympanic retraction pockets are invaginations of the tympanic membrane into the middle ear cleft caused by Eustachian tube dysfunction, which interferes with proper middle ear ventilation.⁵ The diagnosis of a “dangerous” or high-risk retraction pocket is proposed when the bottom of the pocket becomes hidden to the otomicroscope and/or starts retaining skin, because this may lead to primary acquired cholesteatoma.¹ Given that there is a continuum from tympanic retraction pockets to small cholesteatomas, the distinction between retraction pockets that have already developed a cholesteatoma and those that have not remains a problem in otologic surgery because conventional clinical and radiologic methods are often insufficient. In addition, dangerous retraction pockets and small cholesteatomas share similar clinical signs and symptoms, and it is often impossible to differentiate them via otomicroscopy. A substantial number of such patients undergo surgical procedures such as mastoidectomies or atticotomies, but only a subset actually have cholesteatomas.CT is the most widely used imaging technique for the detection of a middle ear mass and assessing tympanomastoid anatomy and the extent of bone erosion.⁶ However, it is nonspecific for cholesteatoma and relies on indirect signs for its diagnosis.^7,8 More recently, MR imaging techniques have been used to differentiate cholesteatoma from other middle ear masses, especially T1-weighted delayed postcontrast imaging and DWI.^9,10DWI techniques are based on the restriction of movement of water molecules, such as that caused by keratin-filled cholesteatomas, producing a hyperintense signal.¹¹ Conventional EPI has been displaced by non-EPI techniques when the temporal bone is the focus, because these sequences have fewer artifacts and thinner sections, allowing the detection of cholesteatomas as small as 2 mm.¹² Several studies of non-echo-planar (EP) DWI have provided excellent sensitivity and specificity for the detection of cholesteatomas. Currently, MR imaging is suggested when the diagnosis of cholesteatoma cannot be established by other means, often in the setting of congenital and residual/recurrent disease.¹⁰The purpose of this study was to evaluate the sensitivity and specificity of non-EP DWI for the detection of cholesteatomas in skin-retaining and/or otomicroscopically inaccessible tympanic retraction pockets.     

High-Resolution MRI Vessel Wall Imaging: Spatial and Temporal Patterns of Reversible Cerebral Vasoconstriction Syndrome and Central Nervous System Vasculitis

BACKGROUND AND PURPOSE:High-resolution MR imaging is an emerging tool for evaluating intracranial artery disease. It has an advantage of defining vessel wall characteristics of intracranial vascular diseases. We investigated high-resolution MR imaging arterial wall characteristics of CNS vasculitis and reversible cerebral vasoconstriction syndrome to determine wall pattern changes during a follow-up period.MATERIALS AND METHODS:We retrospectively reviewed 3T-high-resolution MR imaging vessel wall studies performed on 26 patients with a confirmed diagnosis of CNS vasculitis and reversible cerebral vasoconstriction syndrome during a follow-up period. Vessel wall imaging protocol included black-blood contrast-enhanced T1-weighted sequences with fat suppression and a saturation band, and time-of-flight MRA of the circle of Willis. Vessel wall characteristics including enhancement, wall thickening, and lumen narrowing were collected.RESULTS:Thirteen patients with CNS vasculitis and 13 patients with reversible cerebral vasoconstriction syndrome were included. In the CNS vasculitis group, 9 patients showed smooth, concentric wall enhancement and thickening; 3 patients had smooth, eccentric wall enhancement and thickening; and 1 patient was without wall enhancement and thickening. Six of 13 patients had follow-up imaging; 4 patients showed stable smooth, concentric enhancement and thickening; and 2 patients had resoluton of initial imaging findings. In the reversible cerebral vasoconstriction syndrome group, 10 patients showed diffuse, uniform wall thickening with negligible-to-mild enhancement. Nine patients had follow-up imaging, with 8 patients showing complete resolution of the initial findings.CONCLUSIONS:Postgadolinium 3T-high-resolution MR imaging appears to be a feasible tool in differentiating vessel wall patterns of CNS vasculitis and reversible cerebral vasoconstriction syndrome changes during a follow-up period.

Reversible cerebral vasoconstriction syndrome (RCVS) and CNS vasculitis are 2 distinct cerebrovascular disease entities with overlapping presenting symptoms of headache and, not uncommonly, neurologic deficits, which may be secondary to ischemic and/or hemorrhagic stroke.^1–4 Expeditious diagnosis is critical to discriminate the 2 disease entities to initiate appropriate and timely treatment.⁴ In addition to clinical and laboratory work-up, DSA, MRA, and CTA are the preferred imaging modalities, essential to diagnosis and disease management. However, current vascular imaging fails to distinguish both entities, often due to shared nonspecific luminal findings on DSA, MRA, and CTA.^1,5Radiographic discrimination using current vascular imaging is difficult due to the relative thinness of intracranial vessel walls, at most, 1–2 mm thick in the largest intracranial vessels. The size scale is near the resolution limit of present imaging technology. While DSA provides superior resolution, it only images the vessel lumen. CTA and MR imaging, on the other hand, can image extraluminal tissue; however, the resolution is near the limit for imaging the vessel wall. Of these methods, MR imaging tends to be the technique of choice due to its superior soft-tissue contrast compared with CTA. Thus, the successful application of MR imaging to scan the vessel wall would require using a higher resolution than is routinely used in clinical practice while using standard clinical imaging hardware. This is accomplished by extending the technical parameters of a clinical MR imaging scanner as much as possible within the limits of the scan time and signal and is termed “high-resolution MR imaging” (HRMRI).The utility of HRMRI in characterizing vessel wall patterns of intracranial artery diseases has been investigated.^6–9 Recent studies have identified distinct characteristics of arterial wall thickening and wall enhancement in RCVS and CNS vasculitis.^6,7 While these studies have described spatial patterns on HRMRI, they have not described the temporal evolution of these diseases; this information could further aid diagnosis and management. The aim of this study was to describe the spatial patterns and temporal evolution of RCVS and CNS vasculitis by examining vessel wall characteristics during a follow-up period by using 3T-HRMRI and thereby assess the potential of HRMRI to serve as a surveillance technique to identify changes in wall morphology with disease progression or remission. We hypothesized that 3T-HRMRI vessel wall imaging may differentiate the spatial and temporal patterns of RCVS and CNS vasculitis.     

Radiology Reports for Incidental Thyroid Nodules on CT and MRI: High Variability across Subspecialties

BACKGROUND AND PURPOSE:Variability in radiologists'' reporting styles and recommendations for incidental thyroid nodules can lead to confusion among clinicians and may contribute to inconsistent patient care. Our aim was to describe reporting practices of radiologists for incidental thyroid nodules seen on CT and MR imaging and to determine factors that influence reporting styles.MATERIALS AND METHODS:This is a retrospective study of patients with incidental thyroid nodules reported on CT and MR imaging between January and December 2011, identified by text search for “thyroid nodule” in all CT and MR imaging reports. The studies included CT and MR imaging scans of the neck, spine, and chest. Radiology reports were divided into those that mentioned the incidental thyroid nodules only in the “Findings” section versus those that reported the incidental thyroid nodules in the “Impression” section as well, because this latter reporting style gives more emphasis to the finding. Univariate and multivariate analyses were performed to identify radiologist, patient, and nodule characteristics that influenced reporting styles.RESULTS:Three hundred seventy-five patients met the criterion of having incidental thyroid nodules. One hundred thirty-eight (37%) patients had incidental thyroid nodules reported in the “Impression” section. On multivariate analysis, only radiologists'' divisions and nodule size were associated with reporting in “Impression.” Chest radiologists and neuroradiologists were more likely to report incidental thyroid nodules in the “Impression” section than their abdominal imaging colleagues, and larger incidental thyroid nodules were more likely to be reported in “Impression” (P ≤ .03). Seventy-three percent of patients with incidental thyroid nodules of ≥20 mm were reported in the “Impression” section, but higher variability in reporting was seen for incidental thyroid nodules measuring 10–14 mm and 15–19 mm, which were reported in “Impression” for 61% and 50% of patients, respectively.CONCLUSIONS:Reporting practices for incidental thyroid nodules detected on CT and MR imaging are predominantly influenced by nodule size and the radiologist''s subspecialty. Reporting was highly variable for nodules measuring 10–19 mm; this finding can be partially attributed to different reporting styles among radiology subspecialty divisions. The variability demonstrated in this study further underscores the need to develop CT and MR imaging practice guidelines with the goal of standardizing reporting of incidental thyroid nodules and thereby potentially improving the consistency and quality of patient care.

Incidental thyroid nodules (ITNs) are a common radiologic finding, seen in 1 in 6 patients undergoing CT and MR imaging examinations of the neck.^1,2 Unlike nodules seen on sonography, there are no reliable signs of malignancy and no well-accepted guidelines for reporting ITNs detected on CT and MR imaging. Consequently, the current practice of reporting thyroid nodules on CT and MR imaging by radiologists is highly variable.³ Some radiologists may report all ITNs because there is a chance that an ITN could be malignant. Other radiologists may not report any ITNs because thyroid cancers in ITNs are relatively uncommon⁴ and small thyroid cancers often have an indolent course.^5,6 In particular, reporting an ITN in the “Impression” section of a radiology report provides more emphasis of the finding and may increase the chance of further work-up.Different recommendations for patients with the same nodule characteristics and clinical history are problematic because they can lead to variation in practice patterns, potential variation in the quality of patient care, and anxiety for patients, and they can potentially increase health care costs from the performance of more imaging studies, biopsies, and diagnostic surgeries.^2,7–9 Although some incidental cancers may be diagnosed and treated at an earlier stage, >50% of patients with ITNs that have surgery will ultimately be diagnosed with benign disease.^10,11The variation in reporting styles for ITNs seen on CT and MR imaging has been measured in a recent study, which surveyed radiologists on how they reported different scenarios varying in nodule size and patient history.³ The study demonstrated high variability of ITN reporting, with an overall mean agreement in reporting style of 53% and lower rates of agreement for smaller nodules. A limitation of a survey, however, is that it may not accurately reflect what a radiologist actually does in practice. Another study evaluated reporting practices for ITNs based on radiology reports for cervical spine CT.¹² The authors found that recommendations for ITNs are made inconsistently and the type of management recommended is variable. However, variability in reporting may have been underestimated in their study because it was limited to CT reports issued only by emergency radiologists and did not encompass the reporting practices of abdominal, chest, and neuroimaging radiologists. In addition, the authors did not differentiate between ITNs reported in the “Impression” section of the report versus only the “Findings” section. To fully examine variability in reporting of ITNs, a study should evaluate the reporting style, encompass all radiology subspecialties, and include all CT and MR imaging studies that may lead to detection of ITNs.The purpose of this study was to describe the reporting practices of radiologists for ITNs seen on CT and MR imaging and to determine the factors associated with reporting ITNs in the “Impression” section of the radiology report. We hypothesized that reporting styles would be influenced not only by nodule and patient characteristics but also by radiologist-specific factors, such as subspecialty training and years of experience. Understanding factors associated with variation in reporting practices among radiologists may help to standardize practice patterns, and demonstration of highly variable practices would support the need for guidelines for reporting ITNs seen on CT and MR imaging.     

Visualization of the Trochlear Nerve in the Cistern with Use of High-Resolution Turbo Spin-Echo Multisection Motion-Sensitized Driven Equilibrium

BACKGROUND AND PURPOSE:The trochlear nerve is so thin that it is rarely observed with MR imaging. Therefore, we used high-resolution MSDE to reliably visualize the cisternal segments of the trochlear nerve.MATERIALS AND METHODS:Participants were 10 healthy young adults (mean age, 24 years), and 20 trochlear nerves were examined. HR-MRC, BS-MRC, and HR-MSDE were performed. A neuroradiologist judged the visibility of the trochlear nerves as 1 of 4 grades (“Excellent,” “Good,” “Fair,” and “Not”) in each MR imaging sequence. The findings were then statistically analyzed with the χ² test.RESULTS:Of all 20 trochlear nerves, 6 with HR-MRC, 13 with BS-MRC, and 18 with HR-MSDE were judged as “Excellent.” CSF flow-related artifacts and vessels in the cistern and cerebellar tentorium in HR-MRC tended to prevent the neuroradiologists from identifying the trochlear nerve. Vessels in the cistern and cerebellar tentorium in BS-MRC also tended to prevent the neuroradiologists from identifying the trochlear nerve. Compared with other sequences, HR-MSDE visualized the trochlear nerve more often. The χ² test revealed statistically significant differences among the 3 MR imaging sequences (P < .01). The scan time of HR-MSDE was approximately 1.5–2.2 times longer than that of the other sequences.CONCLUSIONS:HR-MSDE is able to clearly visualize the trochlear nerve and has the same or better ability to delineate the trochlear nerve compared with other MR imaging sequences, though its long scan time does not yet yield practical use.

Trochlear nerve palsy is clinically characterized by vertical diplopia (incomitant hypertropia that increases on tilting of the head toward the paralyzed site [Bielschowsky test]), excyclotropia, and head tilt.^1,2 The trochlear nerve is easily injured by surgery, head trauma, brain herniation, and other insults.³ Imaging assessment of the trochlear nerve is more difficult than other cranial nerves, as the fourth cranial nerve is much thinner than the other cranial nerves and has a complex course in the basal cisterns. The trochlear nerve is the only cranial nerve that originates from the mesencephalic dorsum and runs along the cerebellar tentorium as it courses to the cavernous sinus.^4–7 Arteries and veins surround the trochlear nerve in a complicated manner. Given the small size of the nerve and complex cisternal anatomy, it has been difficult to reliably identify the trochlear nerve by MR imaging and other imaging modalities.TSE-MSDE is a new MR imaging technique similar to diffusion-weighted imaging that has been applied to the evaluation of atherosclerotic plaque in the coronary and carotid arteries, as well as brain metastases.^8,9 TSE-MSDE has also been applied for assessment of the existence of brain metastasis with contrast media.¹⁰ This method takes advantage of a preparative sequence, a diffusion pulse with a very low b-value consisting of 3 nonselective radio-frequency pulses with flip angles of 90–180–90°, and symmetric gradients around the 180° pulse. It causes phase dispersion of blood and CSF spins by using a magnetic field gradient and suppresses any flow signals.¹¹ TSE-MSDE is able to clearly show only cranial nerves in the cistern with no flow signal.¹² We hypothesized that TSE-MSDE may be able to effectively visualize the trochlear nerve because it can suppress any signals in the cistern. The purpose of our study was to assess visualization of the trochlear nerve in the cistern by using TSE-MSDE.     

Tapering of the Cervical Spinal Canal in Patients with Distended or Nondistended Syringes Secondary to Chiari Type I Malformation

BACKGROUND AND PURPOSE:Steeper tapering of the cervical spinal canal as documented in recent studies is thought to have a role in the pathophysiology of Chiari malformation-associated syringomyelia. This study aimed to determine whether taper ratio of the cervical spinal canal differs between patients with distended and nondistended syringes.MATERIALS AND METHODS:Seventy-seven adolescents (10–18 years) were divided into 2 groups: 44 with distended syrinx and 33 with nondistended syrinx. On T2-weighted MR images, anteroposterior diameter of the spinal canal was measured at each cervical level, and a linear trend line was fit by least squares regression to calculate the taper ratio. Taper ratios were compared between the 2 groups and further evaluated with respect to age and sex.RESULTS:In the nondistended group ND, the taper ratios for C1–C7, C1–C4, and C4–C7 averaged −0.73 ± 0.57, −1.61 ± 0.98, and −0.04 ± 0.54, respectively, all of which were significantly steeper than those observed in the distended group (P = .001, .004, and .033, respectively). Regarding the average diameters plotted by cervical level, the narrowest region of the canal was found to occur at C4 in both groups. In addition, no significant differences in taper ratio were noted between males and females, or between older (>14 years) and younger patients (≤14 years).CONCLUSIONS:Taper ratios of the cervical spinal canal were found to be different between patients with distended and nondistended syringes, indicating a reciprocal interaction between the syrinx and the cervical spine anatomy.

Chiari malformation type I (CMI) is the leading cause of syringomyelia (SM), a debilitating disorder that can give rise to neurologic impairments including motor weakness and sensory disturbance.^1–3 To date, the exact pathogenesis responsible for SM associated with CMI remains incompletely understood. Although numerous theories and hypotheses have been proposed to explicate the mechanisms underlying such pathologic entity,^4–7 none thoroughly elucidated the clinical and radiologic findings within the disease spectrum.According to a prevailing concept, altered CSF flow at the craniovertebral junction is one of the essential elements in the pathophysiology of SM and hypothetically causes the neurologic signs and symptoms associated with CMI.^8–11 Pinna et al¹² reported that the elongation of the systolic flow might prolong the condition of elevated spinal subarachnoid pressure in patients with CMI. Using computational flow analysis in an idealized 3D model of the subarachnoid space, Roldan et al¹³ and Linge et al¹¹ found that the peak CSF velocities increased progressively from the foramen magnum to C4 or C5. These findings, coupled with the mesodermal dysgenesis theory as evidenced by hypoplasia of the posterior cranial fossa,^14,15 imply an abnormal cervical spinal canal anatomy in patients with CMI. In an attempt to verify this hypothesis, Hirano et al¹⁶ and Hammersley et al¹⁷ investigated tapering of the upper cervical spinal canal, and as steeper taper ratio was found in patients with CMI as compared with healthy controls, they speculated that such bony variations might increase the pressure gradients between the cranial and caudal ends of the spinal canal, resulting in dysfunctional CSF flow and thus favoring the formation of a syrinx.Despite the elegance of the work of Hirano et al¹⁶ and Hammersley et al,¹⁷ which added an interesting twist to the pathomechanism of SM, their theory fails to account for the influence of a syrinx upon morphology of the cervical spinal canal. Clinically, it is observed that patients with a distended syrinx tend to have regional enlargement of the spinal canal. We, therefore, set out to determine whether taper ratio of the cervical spinal canal differs between patients with distended and nondistended syringes secondary to CMI.     

Comparison of CSF Distribution between Idiopathic Normal Pressure Hydrocephalus and Alzheimer Disease

BACKGROUND AND PURPOSE:CSF volumes in the basal cistern and Sylvian fissure are increased in both idiopathic normal pressure hydrocephalus and Alzheimer disease, though the differences in these volumes in idiopathic normal pressure hydrocephalus and Alzheimer disease have not been well-described. Using CSF segmentation and volume quantification, we compared the distribution of CSF in idiopathic normal pressure hydrocephalus and Alzheimer disease.MATERIALS AND METHODS:CSF volumes were extracted from T2-weighted 3D spin-echo sequences on 3T MR imaging and quantified semi-automatically. We compared the volumes and ratios of the ventricles and subarachnoid spaces after classification in 30 patients diagnosed with idiopathic normal pressure hydrocephalus, 10 with concurrent idiopathic normal pressure hydrocephalus and Alzheimer disease, 18 with Alzheimer disease, and 26 control subjects 60 years of age or older.RESULTS:Brain to ventricle ratios at the anterior and posterior commissure levels and 3D volumetric convexity cistern to ventricle ratios were useful indices for the differential diagnosis of idiopathic normal pressure hydrocephalus or idiopathic normal pressure hydrocephalus with Alzheimer disease from Alzheimer disease, similar to the z-Evans index and callosal angle. The most distinctive characteristics of the CSF distribution in idiopathic normal pressure hydrocephalus were small convexity subarachnoid spaces and the large volume of the basal cistern and Sylvian fissure. The distribution of the subarachnoid spaces in the idiopathic normal pressure hydrocephalus with Alzheimer disease group was the most deformed among these 3 groups, though the mean ventricular volume of the idiopathic normal pressure hydrocephalus with Alzheimer disease group was intermediate between that of the idiopathic normal pressure hydrocephalus and Alzheimer disease groups.CONCLUSIONS:The z-axial expansion of the lateral ventricle and compression of the brain just above the ventricle were the common findings in the parameters for differentiating idiopathic normal pressure hydrocephalus from Alzheimer disease.

Idiopathic normal pressure hydrocephalus (iNPH) has been diagnosed with several highly sensitive radiologic findings since the evidence-based guidelines for the diagnosis and management of iNPH were announced.^1–11 Due to the expansion of the lateral ventricles toward the vertex, upward displacement of the superior parietal lobule and decrease of the subarachnoid space at part of the high parietal convexity area are specific morphologic features for iNPH, called “disproportionately enlarged subarachnoid-space hydrocephalus (DESH).”¹ As an alternative to the Evans index, we recently proposed that the “z-Evans index,” which was defined as the maximum z-axial length of the frontal horns of the lateral ventricles to the maximum cranial z-axial length, was useful for iNPH diagnosis.¹² iNPH occurs in the elderly population prone to many types of comorbidities including Alzheimer disease (AD).^13–21 Therefore, differential diagnosis between iNPH and AD with brain atrophy is important, though the quantitative rating system on MR imaging to distinguish iNPH from AD with brain atrophy has not yet been established, to our knowledge.A new automated segmentation technique by using a simple threshold algorithm has been developed, taking advantage of the high sensitivity to detect CSF on the T2-weighted 3D spin-echo sampling perfection with application-optimized contrasts by using different flip angle evolution (SPACE) sequence.^12,22–24 The aim of the present study was to establish a novel representative characteristic of CSF volume and distribution, which can differentiate iNPH from AD.     

Prenatal Diagnosis of Fetal Ventriculomegaly: Agreement between Fetal Brain Ultrasonography and MR Imaging

BACKGROUND AND PURPOSE:Accurate measurement of the lateral ventricles is of paramount importance in prenatal diagnosis. Possible conflicting classifications caused by their measurement in different sectional planes by sonography and MR imaging are frequently raised. The objective of our study was to evaluate the agreement between ultrasonography and MR imaging in the measurement of the lateral ventricle diameter in the customary sectional planes for each technique.MATERIALS AND METHODS:Measurement of both lateral ventricles was performed prospectively in 162 fetuses from 21 to 40 weeks of gestational age referred for evaluation due to increased risk for cerebral pathology. The mean gestational age for evaluation was 32 weeks. The measurements were performed in the customary plane for each technique: axial plane for sonography and coronal plane for MR imaging.RESULTS:The 2 techniques yielded results in substantial agreement by using intraclass correlation and κ coefficient score tests. When we assessed the clinical cutoff of 10 mm, the κ score was 0.94 for the narrower ventricle and 0.84 for the wider ventricle, expressing almost perfect agreement. The Bland-Altman plot did not show any trend regarding the actual width of the ventricle, gestational week, or interval between tests. Findings were independent for fetal position, sex, and indication for examination.CONCLUSIONS:Our study indicates excellent agreement between fetal brain ultrasonography and MR imaging as to the diagnosis of fetal ventriculomegaly in the customarily used sectional planes of each technique.

Ventricular dilation is one of the most common, prenatally diagnosed cerebral abnormalities.^1,2 “Ventriculomegaly” is defined as an atrial diameter exceeding 10 mm.^3,4 The prognosis of ventricular dilation depends on the degree of dilation and the presence of associated cerebral or extracerebral abnormalities.⁵ Thus, accurate measurement of the lateral ventricles is of paramount importance in prenatal diagnosis. Recently, guidelines for the assessment of the diameter of the lateral ventricles by using the axial transventricular plane as part of routine fetal sonographic evaluation have been suggested.^6,7MR imaging of the fetal CNS is a complementary tool and is performed following detection of abnormalities identified by sonography. The common belief is that fetal CNS MR imaging is more accurate than sonography, particularly when evaluation for associated anomalies is required, when the mother is obese, or when more precise measurement of the ventricular diameter is required.⁸Measurement of lateral ventricle diameter by using MR imaging is performed on a coronal plane.⁹ Measurement of lateral ventricle diameter by using ultrasound is performed on an axial plane.⁶ This variation may raise possible conflicting classifications due to different sectional planes or use of different tools. The aim of our study was to evaluate the agreement between ultrasonography and MR imaging in the measurement of the lateral ventricle diameter in the customary sectional planes for each technique in prenatal diagnosis.     

Carotid Bulb Webs as a Cause of “Cryptogenic” Ischemic Stroke

BACKGROUND AND PURPOSE:Carotid webs are intraluminal shelf-like filling defects at the carotid bulb with recently recognized implications in patients with recurrent ischemic stroke. We sought to determine whether carotid webs are an under-recognized cause of “cryptogenic” ischemic stroke and to estimate their prevalence in the general population.MATERIALS AND METHODS:A retrospective review of neck CTA studies in young patients with cryptogenic stroke over the past 6 years (n = 33) was performed to determine the prevalence of carotid webs compared with a control group of patients who received neck CTA studies for reasons other than ischemic stroke (n = 63).RESULTS:The prevalence of carotid webs in the cryptogenic stroke population was 21.2% (95% CI, 8.9%–38.9%). Patients with symptomatic carotid webs had a mean age of 38.9 years (range, 30–48 years) and were mostly African American (86%) and women (86%). In contrast, only 1.6% (95% CI, 0%–8.5%) of patients in the control group demonstrated a web. Our findings demonstrate a statistically significant association between carotid webs and ischemic stroke (OR = 16.7; 95% CI, 2.78–320.3; P = .01).CONCLUSIONS:Carotid webs exhibit a strong association with ischemic stroke, and their presence should be suspected in patients lacking other risk factors, particularly African American women.

Carotid artery webs are shelf-like intraluminal protrusions in the carotid bulb with emerging implications related to recurrent ischemic stroke.^1,2 Most carotid web cases have been previously described with conventional angiography.^3,4 More recently, the imaging characteristics on CTA have also been established. The typical appearance of a carotid web on CTA is a focal, gracile intraluminal filling defect along the posterior wall of the carotid bulb.^1,5 Superimposed thrombus has also been described, which is thought to be related to sluggish/turbulent blood flow produced by the filling defect.⁵Carotid webs also have been referred to as an atypical variant of fibromuscular dysplasia, with intimal fibrosis and hyperplasia on histology in contrast to the classic, medial variant.^3,6 Typical fibromuscular dysplasia occurs in middle-aged white women, with a classic “string of beads” imaging appearance, and does not have a direct association with ischemic stroke.^6,7Although considered a rare entity, a significant proportion of reported carotid web cases have been associated with recurrent ischemic strokes, most frequently in younger adults who lack other known risk factors.¹ Recent studies have revealed a mean age between 45 and 50 years in patients with carotid webs and associated ipsilateral carotid territory ischemic strokes, occurring more frequently in women than men.^1,5,8 There is limited reporting on the prevalence of carotid webs in the stroke population. A recent report on an Afro-Caribbean population demonstrated a 23% prevalence of carotid webs in young patients with ischemic stroke and a 7% prevalence among control patients.⁸ Up to one-third of all patients presenting with ischemic strokes lack an identifiable cause and are classified as “cryptogenic” in etiology, with most of these cases occurring in younger patients.⁹ Webs may be an under-recognized entity because of their subtle morphology and a lack of familiarity amongst radiologists and clinicians with this lesion. They could account for a significant portion of cryptogenic strokes, particularly in young adults.The purpose of our study was to determine the prevalence of carotid webs in a group of patients previously classified as having cryptogenic stroke.     

Effect of Core Laboratory and Multiple-Reader Interpretation of Angiographic Images on Follow-Up Outcomes of Coiled Cerebral Aneurysms: A Systematic Review and Meta-Analysis

BACKGROUND AND PURPOSE:Reported rates of recanalization following coil embolization vary widely across studies. Some confounders are known to affect outcomes but others remain questionable. In the current study, we assess differences in reported angiographic outcomes for cerebral aneurysms treated with coil embolization as a function of single vs multiple readers and site investigator vs core laboratory settings.MATERIALS AND METHODS:Our systematic review covered 1999–2011 by using Ovid MEDLINE and EMBASE. Search terms were subarachnoid hemorrhage, intracranial aneurysms, endovascular treatment, and coiling. Inclusion criteria were >50 aneurysms and available imaging follow-up. Study characteristics of interest were readers at the treating site(s) or at an independent core imaging facility, single vs multiple readers, number of aneurysms treated, mean aneurysm size, mean follow-up time, coil type, initial rupture status, and angiographic follow-up. We defined “unfavorable angiographic outcome” as either “recanalization,” <90% occlusion, or “incomplete occlusion.”RESULTS:There were 104 (2.6%) of 4022 studies that fulfilled our inclusion criteria, comprising a total of 22,134 treated aneurysms, of which 15,969 (72.1%) had reported angiographic follow-up. The overall unfavorable outcome rate was 17.8% (2955/15,969 aneurysms). Eight (7.7%) of 104 studies reported core laboratory readings in which the pooled rate of unfavorable outcomes was 0.23 (95% CI, 0.19–0.28) compared with 0.16 (95% CI, 0.14–0.18) in readings from the treating sites (P < .001). The multivariate meta-regression suggested that core laboratory interpretation was significant for unfavorable outcomes (OR, 5.60; 95% CI, 2.01–15.60; P = .001), after adjustment for initial rupture status, aneurysm size, follow-up duration, and coil type. No significant association was found with use of multiple readers.CONCLUSIONS:Core laboratory studies tend to report higher rates of unfavorable outcomes compared with self-reported studies.

Endovascular coiling has become the first-line treatment of cerebral aneurysms after the ISAT. Current recommendations¹ suggest ongoing angiographic or MR angiographic follow-up to ensure radiographic stability and direct subsequent management, including the possibility of re-treating the patient. Reported rates of “unfavorable” angiographic outcome vary markedly among studies. Some of this reported variability may reflect real differences in outcome because rupture status, time since treatment, aneurysm size, and neck width have been shown to substantially affect rates of recanalization.^2–6 Other important factors determining rates of “unfavorable” outcome relate not to the actual angiographic result but rather from differences in reporting nomenclature, with numerous and different scales and terminology used across studies. Furthermore, angiographic interpretation even of the same scale, as with any other diagnostic tests, may be subject to intraobserver and interobserver variability.In addition to the numerous factors listed above, other study design features might influence reported outcomes. For example, it has been shown in the cardiology literature⁷ that site readings (ie, angiographic readings done by the operators themselves) may be significantly different than readings performed in an independent core laboratory facility. Furthermore, use of multiple readers has been hypothesized to affect reported outcomes.⁸The current literature focusing on angiographic recanalization after coil embolization includes numerous and different strategies for image interpretation, including those done at the treating facility as well as those in a core laboratory. In addition, some reported studies rely on single observers,^9–11 whereas others report multiple-reader outcomes.^12–14 However, the impact of setting (site readings vs core facility interpretation) as well as single-reader vs multiple-reader studies remains poorly studied. In our current study, we assessed differences in reported angiographic outcomes for cerebral aneurysms treated with coil embolization as a function of single vs multiple readers and site investigator vs core laboratory settings.     

Middle Cerebral Artery Stenosis in Patients with Acute Ischemic Stroke and TIA in Israel

BACKGROUND AND PURPOSE:Middle cerebral artery stenosis is not frequent but a well-established cause of first and recurrent ischemic stroke. Our aim was to investigate middle cerebral artery stenosis in the biethnic (Jewish and Arab) population of patients with acute ischemic stroke and transient ischemic attack in northern Israel.MATERIALS AND METHODS:The study population included 1344 patients from the stroke data registry who had been hospitalized in the neurologic department because of acute ischemic stroke (1041) or TIA (303) and had undergone transcranial Doppler sonographic examination during the hospitalization.RESULTS:Of the 1344 patients, 120 (8.9%) were found to have MCA stenosis. The patients with intracranial stenosis were older and had more vascular risk factors (hypertension, diabetes, and hyperlipidemia) and vascular diseases (ischemic heart and peripheral vascular disease) than those without intracranial stenosis. Logistic regression analysis revealed that diabetes (P = .002) and peripheral vascular disease (P = .01), but not ethnicity, were independent and significant predictors for the presence of MCA stenosis.CONCLUSIONS:An independent and significant correlation was found between MCA stenosis and vascular risk factors (diabetes mellitus) and vascular diseases, thus emphasizing the similarity of intracranial MCA stenosis and other vascular diseases originating from atherosclerosis. There was no influence of ethnicity on intracranial stenosis in our population.

Intracranial stenosis is most commonly due to an atherosclerotic lesion of the intracranial vessels, leading to subsequent narrowing or occlusion of these vessels.^1,2 This condition is being increasingly recognized as an important and underestimated etiology in acute ischemic stroke.^3–5 Differences in the prevalence of intracranial stenosis in various populations have been reported, with the most vulnerable patients seeming to be Asians, Hispanics, and African Americans.^6–10 Because intracranial stenosis usually represents an atherosclerotic lesion, it is not surprising that there is a clear correlation between intracranial stenosis and vascular diseases and vascular risk factors.^11–15The aim of the present study was to search for possible determinants of potentially symptomatic middle cerebral artery stenosis in patients with stroke and transient ischemic attack in a biethnic (Jewish and Arab) population of northern Israel.Many studies in the literature suggest different transcranial Doppler sonography (TCD) parameters (peak systolic velocity, mean velocity) and different values as cutoffs for the diagnosis of intracranial stenosis. There are also many different definitions in the literature of intracranial stenosis (eg, “mild, moderate, and severe,” “less and more than 50%,” “50%–69% and more than 70%,” and so forth). There are still no generally accepted criteria for moderate intracranial stenosis. In this study, potentially symptomatic intracranial stenosis was defined as cases in which TCD examination showed a peak velocity in the middle cerebral artery, either left or right, of ≥140 cm/s. This value was used by some researchers as a criterion correlating with MCA stenosis of ≥50%.^3,16     

Three-Territory DWI Acute Infarcts: Diagnostic Value in Cancer-Associated Hypercoagulation Stroke (Trousseau Syndrome)

BACKGROUND AND PURPOSE:DWI infarcts involving the bilateral anterior and posterior circulation suggest an embolic etiology. In the absence of an identifiable embolic source, we analyzed DWI lesions involving these 3 cerebral territories to determine the diagnostic value for ischemic infarction caused by cancer-associated hypercoagulation.MATERIALS AND METHODS:A retrospective analysis of all brain MR imaging studies at our institution from July 2014 to June 2015 was conducted, yielding 4075 studies. Of those, 17% (n = 709) contained the terms “restricted-diffusion” plus either “numerous,” “innumerable,” “multiple,” or “bilateral.” Of these 709 reports, 6% (n = 41) of DWI lesions involving 3 or more vascular territories of the bilateral anterior and posterior circulation were analyzed.RESULTS:Of the 41 patients, 19 separate etiologies were identified, the most frequent being malignancy-related infarctions (22% [n = 9]) and hypoxic-ischemic injury (12% [n = 5]). Only 2 patients had an indeterminate etiology. The most frequent etiology of infarctions not suspected clinically or radiographically was malignancy (P < .001). Infarctions of malignancy had a characteristic appearance, being nonenhancing, nonring-appearing clusters or single areas of restricted diffusion of 0.5–2 cm with a peripheral location or larger vascular territories, uncommonly in a watershed distribution, and with absence of diffuse cortical ribbon or deep gray nuclei involvement.CONCLUSIONS:Approximately 1 in 5 ischemic infarcts in patients with DWI lesions involving 3 vessel territories are malignancy related. In the absence of an identifiable embolic source, ischemic infarction with cancer-associated hypercoagulation accounts for 75% of cases. Cancer-associated hypercoagulation infarction should be considered, particularly when no other cause is apparent.

Up to 15% of patients with malignancy may experience a thromboembolic cerebrovascular event during their clinical course.¹ In addition, malignancy is frequently overlooked as a cause of stroke and is commonly undiagnosed until a second event occurs.² Though the paraneoplastic hypercoagulable state is complex and not fully understood, it is an established mechanism of thrombosis in malignancy. The importance of diagnosing cancer-associated hypercoagulation is appreciated because it may be the heralding manifestation of occult malignancy. Treatment with heparin has been demonstrated effective in preventing thrombotic events, including stroke.^3,4Trousseau syndrome (TS) is a hypercoagulable state, associated with cancer, that includes various disorders probably involving multiple overlapping mechanisms. It has been suggested the term “Trousseau syndrome” be restricted to unexplained thrombotic events that either precede the diagnosis of an occult visceral malignancy or appear concomitantly with the tumor.⁵ Cerebral infarction, mostly caused by in situ thrombosis in medium and small vessels, is thought to be related to the prothrombic state of TS. Verrucous endocarditises associated with cerebral emboli, infection, or therapy-related strokes are alternative causes of ischemic infarction.^2,6 Given the familiar usage of TS by some authors to refer to cancer-associated hypercoagulation,⁵ we use TS in that context in this discussion.DWI primarily defines ischemic infarcts in malignancy as small and involving multiple vessel territories,^6–9 with the number of territories involved correlating with the likelihood of this syndrome.^4,10–12 However, studies specifically evaluating MR imaging in cerebral infarction with TS and its diagnostic value in establishing causality are lacking. Distinct from prior reports where patient selection was based on the presence of stroke with malignancy or vice versa, our patient selection was based on the presence of numerous, innumerable, multiple, or bilateral lesions on MR imaging. At our institution, we have experienced many cases of 3–cerebral territory infarctions associated with malignancy. However, the association of 3-territory DWI infarcts and malignancy has not been studied.We speculate that selecting patients by using MR criteria allows for a more accurate assessment of diagnosing TS-related infarction compared with selection criteria using history of stroke and cancer because the potential for error exists when cancer history is overlooked or undiagnosed. In this study, we assessed the etiology of DWI-defined 3-territory infarcts, with attention to their diagnostic value in TS-related stroke.     

Optimal Diagnostic Indices for Idiopathic Normal Pressure Hydrocephalus Based on the 3D Quantitative Volumetric Analysis for the Cerebral Ventricle and Subarachnoid Space

BACKGROUND AND PURPOSE:Despite the remarkable progress of 3D graphics technology, the Evans index has been the most popular index for ventricular enlargement. We investigated a novel reliable index for the MR imaging features specified in idiopathic normal pressure hydrocephalus, rather than the Evans index.MATERIALS AND METHODS:The patients with suspected idiopathic normal pressure hydrocephalus on the basis of the ventriculomegaly and a triad of symptoms underwent the CSF tap test. CSF volumes were extracted from a T2-weighted 3D spin-echo sequence named “sampling perfection with application-optimized contrasts by using different flip angle evolutions (SPACE)” on 3T MR imaging and were quantified semiautomatically. Subarachnoid spaces were divided as follows: upper and lower parts and 4 compartments of frontal convexity, parietal convexity, Sylvian fissure and basal cistern, and posterior fossa. The maximum length of 3 axial directions in the bilateral ventricles and their frontal horns was measured. The “z-Evans Index” was defined as the maximum z-axial length of the frontal horns to the maximum cranial z-axial length. These parameters were evaluated for the predictive accuracy for the tap-positive groups compared with the tap-negative groups and age-adjusted odds ratios at the optimal thresholds.RESULTS:In this study, 24 patients with tap-positive idiopathic normal pressure hydrocephalus, 25 patients without response to the tap test, and 23 age-matched controls were included. The frontal horns of the bilateral ventricles were expanded, with the most excessive expansion being toward the z-direction. The CSF volume of the parietal convexity had the highest area under the receiver operating characteristic curve (0.768), the z-Evans Index was the second (0.758), and the upper-to-lower subarachnoid space ratio index was the third (0.723), to discriminate the tap-test response.CONCLUSIONS:The CSF volume of the parietal convexity of <38 mL, upper-to-lower subarachnoid space ratio of <0.33, and the z-Evans Index of >0.42 were newly proposed useful indices for the idiopathic normal pressure hydrocephalus diagnosis, an alternative to the Evans Index.

Idiopathic normal pressure hydrocephalus (iNPH) has been diagnosed since the evidence-based guidelines for diagnosis and management of iNPH were announced in Japan, the United States, and Europe.^1–5 Frequently, patients with iNPH have short-stepped gaits at first, followed by cognitive impairment and urinary incontinence. The Study of iNPH on Neurologic Improvement (SINPHONI) showed that narrow sulci at the high convexity and an enlarged Sylvian fissure with ventricular dilation, which was designated as “disproportionately enlarged subarachnoid-space hydrocephalus (DESH),” were important MR imaging features for iNPH diagnosis.⁶ The SINPHONI also confirmed that a lumbar CSF tap test was a necessary diagnostic test for probable iNPH and predicted a favorable response to a ventriculoperitoneal shunt surgery.⁷Despite the remarkable progress of 3D graphics technology, the Evans Index proposed by William Evans in 1942 has been the most popular index of ventricular enlargement,⁸ and an Evans Index of >0.3 has been adopted as a criterion for ventriculomegaly in the Japanese and international iNPH guidelines.^1–5 However, some studies using volumetric analysis suggested that it was not a sufficient linear index for evaluating ventricular enlargement.^9,10 In recent years, a T2-weighted 3D spin-echo sequence with sampling perfection with application-optimized contrasts by using different flip angle evolutions (SPACE sequence; Siemens, Erlangen, Germany) has been developed.^11–14 This volumetric sequence enables the decrease of specific absorption rate limits and a scan of the whole brain in a single slab and a true isotropic 3D data record with high resolution (voxel size ≤ 1 mm³ without interpolation). Taking advantage of the high sensitivity to detect CSF on the T2-weighted 3D-SPACE sequence, a new automated segmentation technique by using a simple threshold algorithm has been developed.¹⁵ The aim of the present study was to investigate the association between several 1D and 3D parameters of the ventricles and subarachnoid space and the response to the CSF tap test in patients with suspected iNPH in a systematic manner.