Nutrient canal of the fibula

Objective. To investigate the radiological features of the nutrient canal in the fibula. Design and patients. One hundred and seventy-nine dried fibulae were studied regarding the type, number, location, and direction of the nutrient canal. They were classified into a usual type (type I: a radiolucent line confined to the cortex) and an atypical type (type II: a radiolucent line extending beyond the cortex). Results. Among the total of 230 nutrient canals seen on radiography, 197 (86%) were type I and 33 (14%) were type II. On CT scans, the ossified rim of the canal extended into the medullary cavity in type II canals. The most common site was the posteromedial aspect in both type I and type II canals. Type II canals were significantly more common in fibulae with two or three nutrient canals. The frequency of the upward direction was more common in type II canals. Conclusion. Nutrient canals with extension of the ossified rim into the medullary canal are the cause of linear lucency that may simulate a fracture. Their features are slightly different from those of usual canals. Received: 13 July 1999 Revision requested: 20 September 1999 Revision received: 13 October 1999 Accepted: 18 October 1999     

Radioanatomy of the singular nerve canal

The singular canal conveys vestibular nerve fibers from the ampulla of the posterior semicircular canal to the posteroinferior border of the internal auditory meatus. Radiographic identification of this anatomic structure helps to distinguish it from a fracture. It is also a landmark in certain surgical procedures. Computed tomography (CT) examinations of deep-frozen temporal bone specimens were compared with subsequently prepared plastic casts of these bones, showing good correlation between the anatomy and the images. The singular canal and its variable anatomy were studied in CT examinations of 107 patients. The singular canal could be identified, in both the axial and in the coronal planes. Its point of entry into the internal auditory meatus varied considerably. offprint requests to: C. Muren     

Effect of low back posture on the morphology of the spinal canal

Objective. To define the possible mechanism of posture-dependent symptoms of spinal stenosis by measuring the effect of low back posture on morphologic changes of the intervertebral discs and spinal canal in healthy young people. Design.Twenty healthy young volunteers underwent magnetic resonance imaging while supine with their spine in neutral, flexed, extended, and right and left rotational positions. The axial MR images at the middle of the intervertebral discs of L3–4 and L4–5 were analyzed to measure the difference in the size and shape of the intervertebral discs and spinal canal in each posture. Results.  Extension or rotation decreased the sagittal diameters and cross-sectional areas of the dural sac and spinal canal and increased the thickness of the ligamentum flavum, whereas flexion had the opposite effects. The gap between the convex posterior disc margin and the anterior margin of the facet joint on each side, represented as the subarticular sagittal diameter, increased with flexion and decreased with extension or rotation. The direction of rotation did not result in asymmetry of the subarticular sagittal diameter, but right rotation caused thickening of the right ligamentum flavum, and vice versa. The shape and dimensions of the disc did not change significantly according to the positions of the low back. Conclusions.With extension or rotation, the thickness of the ligamentum flavum increased and the posterior margin of the intervertebral disc was approximated to the facet joint without any change in shape and size of the disc. These phenomena result in a decrease in the size of the spinal canal and dural sac in extension or rotation postures in young healthy people without disc degeneration, and may explain the posture-dependent symptom of spinal stenosis. Received: 18 October 1999 Revision requested: 9 November 1999 Revision received: 13 December 1999 Accepted: 17 January 2000     

Posterior semicircular canal dehiscence: a morphologic cause of vertigo similar to superior semicircular canal dehiscence

The aim of this study was to assess imaging findings of posterior semicircular dehiscence on computed tomography and to evaluate incidence of posterior and superior semicircular canal dehiscence in patients presenting with vertigo, sensorineuronal hearing loss or in a control group without symptoms related to the inner ear. Computed tomography was performed in 507 patients presenting either with vertigo (n=128; 23 of these patients suffered also from sensorineuronal hearing loss), other symptoms related to the inner ear, such as hearing loss or tinnitus (n=183) or symptoms unrelated to the labyrinth (n=196). All images were reviewed for presence of dehiscence of the bone, overlying the semicircular canals. Twenty-nine patients had superior semicircular canal dehiscence. Of these patients, 83% presented with vertigo, 10% with hearing loss or tinnitus and the remaining 7% with symptoms unrelated to the inner ear. In 23 patients dehiscence of the posterior semicircular canal was encountered. Of these patients, 86% presented with vertigo, 9% with hearing loss or tinnitus and 5% with symptoms unrelated to the inner ear. Defects of the bony overly are found at the posterior semicircular canal, in addition to the recently introduced superior canal dehiscence syndrome. Significant prevalence of vertigo in these patients suggests that posterior semicircular canal dehiscence can cause vertigo, similar to superior semicircular canal dehiscence. Electronic Publication     

Spinal epidural abscess: correlation between MRI findings and outcome

Our purpose was to determine if specific MRI findings in spinal epidural abscess (SEA), at the time of diagnosis, are associated with the clinical outcome. The clinical records and MRI studies of 18 patients with SEA were reviewed and follow-up was obtained from the outpatient medical record, telephone interview, or both. The association between findings on contrast-enhanced MRI and clinical outcome (weakness, neck or back pain, and incomplete functional recovery) was evaluated. With univariate analysis, narrowing of 50 % or more of the central spinal canal (P = 0.03), peripheral contrast-enhancement (P = 0.05), and abnormal spinal cord signal intensity (P = 0.05) were associated with weakness at follow-up. Persistent neck or back pain was associated with spinal canal narrowing (P = 0.02), peripheral contrast-enhancement (P = 0.02), and an abscess longer than 3 cm (P = 0.04) on MRI. Incomplete clinical recovery was associated with both abscess length (P = 0.01) and the severity of canal narrowing (P = 0.01). Abscess length, enhancement pattern, and severity of canal narrowing can be incorporated in a grading system that can be used to predict outcome. Received: 9 September 1998 Accepted: 6 March 1999     

Computed tomographic features of the bony canal of the cochlear nerve in pediatric patients with unilateral sensorineural hearing loss

Purpose The aim of this study was to evaluate the diameters of the various bony canals of the inner ear in patients with sensorineural hearing loss (SNHL) and establish criteria for detecting hypoplasia of the bony canal of the cochlear nerve. Materials and methods Measurements obtained in 118 patients without inner ear malformations among 160 patients with unilateral SNHL were analyzed. The diameters of the internal auditory canal and the bony canals of the cochlear, vestibular, and facial nerves were measured on transverse or coronal computed tomographic images. Mean values (± SD) were compared between the affected and unaffected ears, and statistical analysis was done. Results The diameter of the bony canal of the cochlear nerve was significantly smaller in affected ears than in unaffected ears (P < 0.01). The affected ears could be divided into groups with (72 ears) and without (46 ears) bony canal stenosis. Conclusions Most (60%) of the patients with unilateral SNHL showed a significant difference in the diameters of the bony canals of the cochlear nerve between the affected and unaffected sides; moreover, the mean value was significantly smaller in affected ears. The diameter of <1.7 mm on transverse images or <1.8 mm on coronal images suggests hypoplasia.     

Widening of the spinal canal and dural ectasia in Marfan's syndrome: assessment by CT

We describe a method for diagnosing dural ectasia (DE) and spinal canal widening (SCW) using CT. We examined 23 patients with Marfan's syndrome (MFS), 17 with Ehlers-Danlos syndrome (EDS) and 29 normal subjects, using six axial slices at the level of the L1-S1 pedicles. Transverse diameters of the vertebral bodies, spinal canal and dural sac were measured and indices were defined to differentiate patients with DE and SCW from normal. Statistical significance was assessed using Student's t -test, χ ²-test and Pearson's correlation coefficient. DE and SCW occurred in 69.6 % and 60.9 % of cases of MFS and in 23.5 % and 35.3 % of EDS respectively. In MFS, prevalence was significantly higher than in the control group. DE was significantly more frequent in MFS than in EDS. A strong correlation existed between DE and SCW in MFS and the control group, but not in EDS. Our system enables quantitative assessment of SCW and DE. The latter is particularly important in subjects suspected of having MFS, in whom it is a common and characteristic sign. Received: 28 September 1998 Accepted: 16 March 1999     

Dural ectasia and conventional radiography in the Marfan lumbosacral spine

Objective. To determine how well conventional radiographic findings can predict the presence of dural ectasia in Marfan patients. Design and patients. Twelve Marfan patients without dural ectasia and 21 Marfan patients with dural ectasia were included in the study. Five radiographic measurements were made of the lumbosacral spine: interpediculate distance, scalloping value, sagittal canal diameter, vertebral body width, and transverse process width. Results. The following measurements were significantly larger in patients with dural ectasia: interpediculate distances at L3–L4 levels (P<0.03); scalloping values at the L1 and L5 levels (P<0.05); sagittal diameters of the vertebral canal at L5–S1 (P<0.03); transverse process to width ratios at L2 (P<0.03). Criteria were developed for diagnosis of dural ectasia in Marfan patients. These included presence of one of the following: interpediculate distance at L4 >38.0 mm, sagittal diameter at S1 >18.0 mm, or scalloping value at L5 >5.5 mm. Conclusion. Dural ectasia in Marfan syndrome is commonly associated with several osseous changes that are observable on conventional radiographs of the lumbosacral spine. Conventional radiography can detect dural ectasia in patients with Marfan syndrome with a very high specificity (91.7%) but a low sensitivity (57.1%). Received: 24 July 2000 Revision requested: 23 August 2000 Revision received: 11 December 2000 Accepted: 18 December 2000     

Determination of cranio-spinal canal compliance distribution by MRI: Methodology and early application in idiopathic intracranial hypertension

Purpose:

To develop a method for derivation of the cranial‐spinal compliance distribution, assess its reliability, and apply to obese female patients with a diagnosis of idiopathic intracranial hypertension (IIH).

Materials and Methods:

Phase contrast‐based measurements of blood and cerebrospinal fluid (CSF) flows to, from, and between the cranial and spinal canal compartments were used with lumped‐parameter modeling to estimate systolic volume and pressure changes from which cranial and spinal compliance indices are obtained. The proposed MRI indices are analogous to pressure volume indices (PVI) currently being measured invasively with infusion‐based techniques. The consistency of the proposed method was assessed using MRI data from seven aged healthy subjects. Measurement reproducibility was assessed using five repeated MR scans from one subject. The method was then applied to compare spinal canal compliance contribution in seven IIH patients and six matched healthy controls.

Results:

In the healthy subjects, as expected, spinal canal contribution was consistently larger than the cranial contribution (average value of 69%). Measurement variability was 8%. In IIH, the spinal canal contribution is significantly smaller than normal controls (60 versus 78%, P < 0.03).

Conclusion:

An MRI‐based method for derivation of compliance indices analogous to PVI has been implemented and applied to healthy subjects. The application of the method to obese IIH patients suggests a spinal canal involvement in the pathophysiology of IIH. J. Magn. Reson. Imaging 2011;. © 2011 Wiley Periodicals, Inc.     

High-resolution dental magnetic resonance imaging of inferior alveolar nerve responses to the extraction of third molars

The objective of this study was to assess whether signal changes can be detected in the neurovascular bundle of the mandibular canal after the extraction of a third molar. We retrospectively analyzed MRI scans of 30 test subjects with healthy mandibles and 41 patients who had had a wisdom tooth extracted. Signal intensities were measured at particular sites in the neurovascular bundle, which were defined as regions of interest (ROI) in the sagittal T1-weighted images before and after intravenous administration of a paramagnetic contrast agent. On the basis of the signal intensity increases that were measured after contrast agent administration, we compared the signal increases obtained for the patients who had received surgical treatment with the results obtained for the population of test subjects with unremarkable mandibles (t-test, P<0.05). Compared with the healthy test subjects, patients who had received surgical treatment showed significantly higher signal intensity increases at two measurement sites, i.e., the second molar and the second premolar (P<0.05). We found no significant differences when the measurements were performed at the first molar (P=0.06), the third molar (P=0.47) and in the area of the ascending mandibular ramus (P=0.79). Compared with a population of healthy test subjects, patients who had their third molars surgically removed show higher signal intensity increases in the neurovascular bundle after intravenous contrast agent administration. The underlying cause may be the higher blood flow in the arteries and veins and the perineural plexus, which may give evidence of the pathophysiological mechanism of nerve damage in the narrow canal as a result of osteotomy.     

Depicting the semicircular canals with inner‐ear MRI: A comparison of the SPACE and TrueFISP sequences

Purpose:

To assess the ability of magnetic resonance imaging (MRI) to depict the semicircular canals of the inner ear by comparing results from the sampling perfection with application‐optimized contrasts by using different flip angle evolutions (SPACE) sequence with those from the true free induction with steady precession (TrueFISP) sequence.

Materials and Methods:

A 1.5‐T MRI system was used to perform an in vivo study of 10 healthy volunteers and 17 patients. A three‐point visual score was employed for assessing the depiction of the semicircular canals and facial and vestibulocochlear nerves and the contrast‐to‐noise ratio (CNR) was computed for the vestibule and pons on images with the SPACE and TrueFIPS sequences.

Results:

There were no susceptibility artifact‐related filling defects with the SPACE sequence. However, the TrueFISP sequence showed filling defects for at least one semicircular canal on both sides in seven cases for healthy subjects and in 10 cases for patients. The CNR with the SPACE sequence was significantly higher than with the TrueFISP sequence (P < 0.05). There was no statistically significant difference in depicting the facial and the vestibulocochlear nerves (P = 0.32).

Conclusion:

For the depiction of the semicircular canal, the SPACE sequence is superior to the TrueFISP sequence. J. Magn. Reson. Imaging 2013;37:652–659. © 2012 Wiley Periodicals, Inc.     

Measurement of spinal canal narrowing,interpedicular widening,and vertebral compression in spinal burst fractures: plain radiographs versus multidetector computed tomography

Objective  To assess the reliability of measurements of spinal canal narrowing, vertebral body compression, and interpedicular widening in burst fractures in radiography compared with multidetector computed tomography (MDCT). Materials and methods  Patients who had confirmed acute vertebral burst fractures over an interval of 34 months underwent both MDCT and radiography. Measurements of spinal canal narrowing, vertebral body compression, and interpedicular widening from MDCT and radiography were compared. Results  The 108 patients (30 female, 78 male, aged 16–79 years, mean 39 years) had 121 burst fractures. Eleven patients had multiple fractures, of which seven were not contiguous. Measurements showed a strong positive correlation between radiography and MDCT (Spearman’s rank sum test: spinal canal narrowing k = 0.50–0.82, vertebral compression k = 0.55–0.72, and interpedicular widening k = 0.81–0.91, all P < 0.05), except for the cervical spine (k = −0.50 to 0.61, with all P > 0.25) and for interpedicular widening in the thoracic spine (k = 0.35, P = 0.115). The average difference in measurements between the modalities was 3 mm or fewer. Conclusion  Radiography demonstrates interpedicular widening, spinal canal narrowing and vertebral compression with acceptable precision, with the exception of those of the cervical spine.     

Congenital absence and aberrant course of the internal carotid artery

We retrospectively reviewed the imaging features of an aberrant course of the internal carotid artery (ICA) in one patient and its unilateral absence in four. Absence of the ICA was initially detected by MRI and MR angiography in both patients who underwent these examinations. CT revealed an abnormal or absent carotid canal in all cases. Radiological diagnosis by MRI and MR angiography could play an important role in the diagnosis. Correspondence to: S. Takahashi     

Closed ruptures of the flexor digitorum tendons: MRI evaluation

Objective. To assess the MRI findings in cases of closed rupture of the flexor digitorum tendons (FDT). Patients and design. Ten patients with a clinical suspicion of rupture of FDT underwent MRI before surgery. None of the patients presented a skin injury. Fingers were imaged using axial T1-weighted SE sequences, three-dimensional GE images, and curved reconstructions. Results. Twelve FDT had surgical confirmation of rupture. Flexor digitorum profundus (FDP) and flexor pollicis longus (FPL) tendons were more frequently ruptured (n=8) than flexor digitorum superficialis (FDS) tendons (n=4). MR images accurately depicted the level of the rupture. The gap between the tendon ends (mean 45 mm, range 21–70 mm) was assessed best with curved reconstructions and was well correlated with the surgical findings. The proximal end mainly retracted into the palm or the carpal tunnel (n=8), and less frequently into the digital canal (n=4). In two cases, the proximal end curled up in the palm, clinically simulating a rupture of a lumbrical muscle in one case. MRI also showed the appearance of the adjacent tendons. Conclusion. MRI accurately depicted the level of rupture and the gap between the tendon ends, which assisted the surgical choice between suture, graft or tendon transfer.     

Multiplanar MR and anatomic study of the mandibular canal.

PURPOSETo evaluate the MR appearance of the mandibular canal and its contents.METHODSCadaveric mandibles were imaged at 1.5 T and 3 T, then sectioned with a cryomicrotome. The size, shape, signal intensity, and pattern of structures in the mandibular canal were identified on MR images by comparing them with corresponding anatomic sections.RESULTSThe inferior alveolar nerve and connective tissue were identified on the 1.5-T and 3-T images in the mandibular canal. Within the nerve the axon bundles were distinguished from the nerve sheath on the 3-T images.CONCLUSIONThis study suggests that MR images can show excellent anatomic detail in the mandibular canal.     

Does the location of a vascular loop in the cerebellopontine angle explain pulsatile and non-pulsatile tinnitus?

The purpose was to investigate patients with unexplained pulsatile and non-pulsatile tinnitus by means of MR imaging of the cerebellopontine angle (CPA) and to correlate the clinical subtype of tinnitus with the location of a blood vessel (in the internal auditory canal or at the cisternal part of the VIIIth cranial nerve). Clinical presentation of tinnitus and perceptive hearing loss were correlated. In 47 patients with unexplained tinnitus, an MR examination of the CPA was performed. Virtual endoscopy reconstructions were obtained using a 3D axial thin-section high-resolution heavily T2-weighted gradient echo constructive interference in steady state (CISS) data-set. High-resolution T2-weighted CISS images showed a significantly higher number of vascular loops in the internal auditory canal in patients with arterial pulsatile tinnitus compared to patients with non-pulsatile tinnitus (P<0.00001). Virtual endoscopy images were used to investigate vascular contacts at the cisternal part of the VIIIth cranial nerve in patients with low pitch and high pitch non-pulsatile tinnitus. A significantly different distribution of the vascular contacts (P=0.0320) was found. Furthermore, a correlation between the clinical presentation of non-pulsatile tinnitus (high pitch and low pitch) and the perceptive hearing loss was found (P=0.0235). High-resolution heavily T2-weighted CISS images and virtual endoscopy of the CPA can be used to evaluate whether a vascular contact is present in the internal auditory canal or at the cisternal part of the VIIIth cranial nerve and whether the location of the vascular contact correlates with the clinical subtype of tinnitus. Our findings suggest that there is a tonotopical structure of the cisternal part of the VIIIth cranial nerve. A correlation between the clinical presentation of tinnitus and hearing loss was found.     

High-resolution CT of the temporal bone in dysplasia of the auricle and external auditory canal.

PURPOSETo determine CT findings in the external, middle, and inner ear of patients with microtia and external auditory canal dysplasia.METHODSWe used high-resolution CT, with multiplanar or axial 1-mm continuous sections, coronal or sagittal reformations, or low-dose spiral acquisitions, to examine 184 temporal bones of children with microtia.RESULTSIn cases of minor microtia, auditory canal stenosis was the most common associated abnormality; in those with major microtia, atresia was predominant. Middle ear malformations depended on the severity of the auricular anomalies. Inner ear changes could also be noted. Ossicle dysplasias occurred in 98% of patients (stapes, 72%), absence of the oval window in 36%, labyrinthine malformations in 13%, closed round window in 6%, facial canal displacement in up to 75%, and aberrations of the vascular canal in 38% of patients with third-grade auricular deformity.CONCLUSIONA variety of external, middle, and, less frequently, inner ear changes were detected in connection with microtia.     

Correlation of panoramic radiography and cone beam CT findings in the assessment of the relationship between impacted mandibular third molars and the mandibular canal

Objectives

The aim of this study was to assess the reliability of four panoramic radiographic findings, both individually and in association, in predicting the absence of corticalization between the mandibular canal and the third molar on cone beam CT (CBCT) images.

Methods

The sample consisted of 72 individuals (142 mandibular third molars) who underwent pre-operative radiographic evaluation before extraction of impacted mandibular third molars. On panoramic radiographs, the most common signs of corticalization (darkening of roots, diversion of mandibular canal, narrowing of mandibular canal and interruption of white line) and the presence or absence of corticalization between the mandibular third molar and the mandibular canal on CBCT images were evaluated.

Results

Darkening of roots and interruption of white line associated with the absence of corticalization between the mandibular third molar and the mandibular canal on CBCT images were statistically significant, both as isolated findings (p = 0.0001 and p = 0.0006, respectively) and in association (p = 0.002). No statistically significant association was observed for the other panoramic radiographic findings, either individually or in association (p > 0.05).

Conclusion

Darkening of roots and interruption of white line observed on panoramic radiographs, both as isolated findings and in association, were effective in determining the risk relationship between the tooth roots and the mandibular canal, requiring three-dimensional evaluation of the case.     

Forward shifting of posterior dural sac during flexion cervical magnetic resonance imaging in Hirayama disease: An initial study on normal subjects compared to patients with Hirayama disease

Objective

Forward shifting of the posterior cervical dural sac is the most important sign in diagnosing Hirayama disease but can also be seen in normal subjects, causing potential diagnostic dilemma. We aim to explore the degree of forward displacement of posterior dural sac in normal subjects compared to that with Hirayama disease.

Materials and methods

50 healthy male teenagers and 3 patients with Hirayama disease were recruited into the control group and patient group, respectively. MR imaging of the cervical spine was performed in both neutral and flexion positions for all subjects, with the following parameters measured: maximal distance of forward shifting of posterior dural sac, dimension of dural sac and spinal cord.

Results

Forward shifting of the posterior cervical dural sac was depicted in 46% of normal subjects upon flexion position but without associated cord compression due to intrinsic expansion of the spinal canal volume. This intrinsic compensatory mechanism was inadequate in diseased patients leading to cord compression with significant increment in ratio of anteroposterior diameter of forward displacement of posterior dural wall/anteroposterior diameter of spinal canal (“x/y”), and decrement in ratio of anteroposterior diameter of spinal cord/perpendicular transverse diameter of spinal cord (“a/b”).

Conclusion

Depicting of forward shifting of posterior dural sac alone on flexion position cannot reliably diagnose Hirayama disease, which should be established only if there is forward shifting of posterior dural sac, plus increased ratio of x/y and decreased ratio of a/b on flexion position from associated mass effect on the spinal cord.     

Intradural extramedullary spinal canal secondary neoplasms: MR findings in 30 patients

The purpose of this study was to describe magnetic resonance findings of intradural spinal canal secondaries and to select the best way of investigating this condition. Thirty patients with a known malignancy [breast carcinoma (n = 14), lung carcinoma (n = 10), other sites (n = 6)] and unexplained neurologic signs were studied with pre- and post-contrast T1-weighted images and T2-weighted images. Cerebrospinal fluid cytology was available in 16 patients and positive in 11 patients. In all the patients, post-contrast T1-weighted images demonstrated abnormal enhanced lesions. Most of them were nodular, located on the conus medullaris and the cauda equina. Few lesions appeared at the thoracic or cervical levels, as nodular or thin areas of enhancement. Pre-contrast T1-weighted sequences failed or were equivocal to detect the lesions. Eighteen of 30 patients had cerebral metastases. Fourteen had osseous metastases. In conclusion, post-contrast T1-weighted sequence is the optimal modality for the diagnostic of intradural spinal canal metastases. Axial and coronal images may be a useful adjunct to precise anatomic changes. T1-weighted and T2-weighted sequences remain necessary when further information is expected on vertebra or soft tissue. Received 25 September 1997; Revision received 29 December 1997; Accepted 5 January 1998