Diagnosis of Menière's disease on MRI: feasibility at 1.5 Tesla.

BACKGROUND: Menière's disease (MD) is clinically characterized by the triad sensorineural hearing loss, tinnitus and/or aural fullness, and vertigo. Endolymphatic hydrops (EH) is the histopathological basis associated with MD, which can be demonstrated on magnetic resonance imaging (MRI). Currently, most studies are done on a 3-T MRI scanner and to date it is believed that EH can only be demonstrated on a 3-T magnet. We report the feasibility of demonstrating EH on a 1.5-T scanner using the standard 20-channel head and neck coil and the current standard 4-h delayed intravenous gadolinium-enhanced three-dimensional fluid-attenuated inversion recovery (3D-FLAIR) sequence. PURPOSE: To investigate whether current standard 4-h delayed intravenous gadolinium-enhanced 3D-FLAIR imaging can demonstrate endolymphatic hydrops on a 1.5-T MRI scanner. MATERIAL AND METHODS: The 3D-FLAIR sequence was taken from a 3-T MRI protocol and tested on a volunteer patient with clinically "definite" MD, after 4-h delayed intravenous contrast injection. Good image quality was obtained after reducing both the matrix and the bandwidth, with clear demonstration of EH. Subsequently, eight more patients with unilateral disease were imaged. Five patients had "definite" MD and four had "probable" MD. RESULTS: We imaged nine patients with unilateral disease and detected EH in eight of nine ears. One patient with "probable" MD did not show any abnormality, but the images were degraded by motion artifacts. CONCLUSION: At a cost of 2 min extra scanning time compared to a 3-T scanner, EH can be confidently demonstrated with the current standard 3D-FLAIR sequence on a 1.5-T magnet.

Comparison of 1.5- and 3-T MR imaging for evaluating the articular cartilage of the knee.

PURPOSE: The aim of this prospective study was to compare routine MRI scans of the knee at 1.5 and 3 T obtained in the same individuals in terms of their performance in the diagnosis of cartilage lesions. METHODS: One hundred patients underwent MRI of the knee at 1.5 and 3 T and subsequent knee arthroscopy. All MR examinations consisted of multiplanar 2D turbo spin-echo sequences. Three radiologists independently graded all articular surfaces of the knee joint seen at MRI. With arthroscopy as the reference standard, the sensitivity, specificity, and accuracy of 1.5- and 3-T MRI for detecting cartilage lesions and the proportion of correctly graded cartilage lesions within the knee joint were determined and compared using resampling statistics. RESULTS: For all readers and surfaces combined, the respective sensitivity, specificity, and accuracy for detecting all grades of cartilage lesions in the knee joint using MRI were 60, 96, and 87% at 1.5 T and 69, 96, and 90% at 3 T. There was a statistically significant improvement in sensitivity (p < 0.05), but not specificity or accuracy (n.s.) for the detection of cartilage lesions at 3 T. There was also a statistically significant (p < 0.05) improvement in the proportion of correctly graded cartilage lesions at 3 T as compared to 1.5 T. CONCLUSION: A 3-T MR protocol significantly improves diagnostic performance for the purpose of detecting cartilage lesions within the knee joint, when compared with a similar protocol performed at 1.5 T. LEVEL OF EVIDENCE: III.

Atypical sino-orbital inflammatory myofibroblastic tumor with bone and cerebral invasion extending to the orbit.

PURPOSE: To report the case of an atypical sino-orbital inflammatory myofibroblastic tumor. METHODS: Case report. RESULTS: A 71-year-old man presented slowly progressive painless diplopia followed by unilateral proptosis of the left eye with slight edema of the upper eyelid. Visual acuity was 0.4 with a relative afferent pupillary defect (RAPD). Abduction and depression of the left eye were limited. Imaging showed a left sino-orbital tumor with mass effect on the medial rectus muscle resulting in proptosis. The lesion showed intracranial extension through the superior orbital fissure with bone erosion and sclerotic bone reaction. Endoscopic ethmoidal, maxillary, and orbital biopsies revealed an inflammatory myofibroblastic tumor. Full blood count showed an eosinophilia while antineutrophil cytoplasmic antibodies and C-reactive protein were negative. To date, 7 cases of orbital myofibroblastic tumor have been described, though none of the prior studies have described bone invasion. CONCLUSIONS: This erosive sino-orbital inflammatory myofibroblastic tumor is a novel finding mimicking a malignant tumor.

The petromastoid canal in the young child: appearance on computed tomography.

OBJECTIVE: The adult petromastoid canal (PMC) is a thin anatomical structure, but in young children, it can be wide on high resolution CT (HRCT) scans. We performed this study to evaluate the year-by-year change in width and shape of the PMC in the young child. MATERIALS AND METHODS: We retrospectively reviewed temporal bone HRCT scans, performed between 2007 and 2012. Eighty children were included (age range: 0.3-6.9 years; median age: 3.1 years; 56% male). All scans had a slice thickness of ≤ 1 mm. RESULTS: The average width of the PMC was 1.95 mm in children < 2 years, compared to 0.83 mm in children ≥ 2 (p < 0.001). We categorized the PMC into 4 subtypes. A bulky (type III) PMC was predominant < 2 years. A thin curvilinear (type I) PMC was more prevalent in the older children. Type II and IV PMC were found infrequently. The PMC width correlated inversely with the degree of pericapsular ossification (p<0.001), and mastoid pneumatisation (p < 0.001). CONCLUSION: A wide PMC (≥ 1 mm) is a common finding in children < 2 years. As children grow older, the PMC progressively narrows. This correlates to increased temporal bone pneumatisation and ossification of the otic capsule.

Diagnosis of liver metastases: can diffusion-weighted imaging (DWI) be used as a stand alone sequence?

OBJECTIVES: To evaluate if diffusion-weighted MRI (DWI) can replace gadolinium-enhanced MRI (Gd-MRI) for diagnosing liver metastases. The diagnostic accuracy of both techniques alone and in combination are compared. MATERIALS AND METHODS: Sixty-eight patients with histologically proven primary extrahepatic tumors were included in this retrospective study. Lesions included 62 metastases and 130 benign lesions. Three image sets (unenhanced T1 and T2/gadolinium enhanced T1 (Gd-MRI), DWI and combination of both) were reviewed independently by 3 observers. The areas under the receiver operating characteristic curves (A(z)), sensitivity and specificity for the 3 image sets were compared. The standard of reference was either histopathology or multi-modality and clinical follow-up. RESULTS: Pooled data showed higher diagnostic accuracy for the combined set (A(z)=0.93) compared to Gd-MRI (p=0.001) and DWI (p<0.0001). No difference was found between the performance of Gd-MRI and DWI (p=0.09). Sensitivity for the combined set was higher than Gd-MRI (p=0.0003) and DWI (p=0.0034). Specificity for DWI was lower than Gd-MRI (p<0.0001) and the combined set (p<0.0001). CONCLUSION: The diagnostic performance of DWI is equal to that of Gd-MRI. DWI alone can be used in patients where gadolinium contrast administration is not allowed. Combination of Gd-MRI and DWI significantly increases diagnostic accuracy.

Middle ear cholesteatoma: non-echo-planar diffusion-weighted MR imaging versus delayed gadolinium-enhanced T1-weighted MR imaging--value in detection.

PURPOSE: To retrospectively compare non-echo-planar (non-EP) diffusion-weighted (DW) imaging, delayed gadolinium-enhanced T1-weighted magnetic resonance (MR) imaging, and the combination of both techniques in the evaluation of patients with cholesteatoma. MATERIALS AND METHODS: This institutional review board-approved study, for which the need to obtain informed consent was waived, included 57 patients clinically suspected of having a middle ear cholesteatoma without a history of surgery and 63 patients imaged before "second-look" surgery. Four blinded radiologists evaluated three sets of MR images: a set of delayed gadolinium-enhanced T1-weighted images, a set of non-EP DW images, and a set of both kinds of images. Overall sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV), as well as intra- and interobserver agreement, were assessed and compared among methods. To correct for the correlation between different readings, a generalized estimating equations logistic regression model was fitted. Results were compared with surgical results, which were regarded as the standard of reference. RESULTS: Sensitivity, specificity, NPV, and PPV were significantly different between the three methods (P < .005). Sensitivity and specificity, respectively, were 56.7% and 67.6% with the delayed gadolinium-enhanced T1-weighted images and 82.6% and 87.2% with the non-EP DW images. Sensitivity for the combination of both kinds of images was 84.2%, while specificity was 88.2%. The overall PPV was 88.0% for delayed gadolinium-enhanced T1-weighted images, 96.0% for non-EP DW images, and 96.3%for the combination of both kinds of images. The overall NPV was 27.0% for delayed gadolinium-enhanced T1-weighted images, 56.5% for non-EP DW images, and 59.6% for the combination of both kinds of images. CONCLUSION: MR imaging for detection of middle ear cholesteatoma can be performed by using non-EP DW imaging sequences alone. Use of the non-EP DW imaging sequence combined with a delayed gadolinium-enhanced T1-weighted sequence yielded no significant increases in sensitivity, specificity, NPV, or PPV over the use of the non-EP DW imaging sequence alone.

Pathology of the vestibulocochlear nerve.

There is a large scala of pathology affecting the vestibulocochlear nerve. Magnetic resonance imaging is the method of choice for the investigation of pathology of the vestibulocochlear nerve. Congenital pathology mainly consists of agenesis or hypoplasia of the vestibulocochlear nerve. Tumoral pathology affecting the vestibulocochlear nerve is most frequently located in the internal auditory canal or cerebellopontine angle. Schwannoma of the vestibulocochlear nerve is the most frequently found tumoral lesion followed by meningeoma, arachnoid cyst and epidermoid cyst. The most frequently encountered pathologies as well as some more rare entities are discussed in this chapter.

Imaging of temporal bone tumors.

Tumoral lesions of the temporal bone are relatively rare. Cross-sectional imaging plays an important role in the description of extension of these lesions. In certain lesions, imaging characteristics are rather specific, giving a clue to diagnosis. The most common tumoral lesions of the external, middle, and inner ear are discussed. Some rare lesions are also highlighted.