Middle ear cholesteatoma: Compared diagnostic performances of two incremental MRI protocols including non-echo planar diffusion-weighted imaging acquired on 3T and 1.5T scanners.

BACKGROUND AND PURPOSE: To compare diagnostic performances for cholesteatoma diagnosis of incremental MRI protocols including non-echo planar diffusion-weighted imaging (DWI) performed on 3T and 1.5T scanners. MATERIALS AND METHODS: Thirty-nine patients with suspected cholesteatoma underwent 3T and 1.5T non-echo planar DWI and additional unenhanced T1-, delayed gadolinium-enhanced T1- and high-resolution T2-weighted standard acquisitions. Patients either underwent surgical tympanoplasty (n=21) or close clinicoradiological follow-up (n=18). Four radiologists independently and prospectively interpreted two incremental MRI protocols, differing in the magnetic field strength of the diffusion-weighted acquisition and comprising the three standard sequences. At each step, diagnostic performances were expressed as sensitivity, specificity, positive predictive value, negative predictive value and accuracy. RESULTS: Forty middle ear lesions including 21 cholesteatomas were identified. Univariate and multivariate analysis did not demonstrate significant reader, sequence addition or DWI magnetic field effect on diagnostic performances. Concerning non-echo planar DWI alone, sensitivity, specificity, positive predictive value, negative predictive value and accuracy ranged between 90.5-100%, 68.4-100%, 76.9-100%, 90.0-100% and 82.5-95.0, respectively. CONCLUSION: Non-echo planar DWI for cholesteatoma diagnosis can be performed on 1.5T or 3T scanners indifferently. High sensitivity and negative predictive value and relatively lower specificity and positive predictive value are achieved by a single non-echo planar DWI protocol.

Assessment of normal values of fractional anisotropy and mean diffusivity of mobile lumbar spine roots by diffuson tensor MRI: comparison between 1.5 and 3T.

PURPOSE: To assess the normal values of fractional anisotropy (FA) and mean diffusivity (MD) of L4, L5 and S1 nerve roots using diffusion tensor imaging (DTI) in healthy volunteers. MATERIALS AND METHODS: 37 subjects without previous history of lumbalgia or radiculalgia were prospectively examined: 27 at 1.5T and 10 at 3T MRI. The protocol included standard anatomical sequences and a DTI acquisition. Nerve root fibers were semi automatically extracted from DTI tractography. FA and MD values were measured at 4 key portions along each L4, L5 and S1 nerve roots. RESULTS: At 1.5T MRI, FA and MD were 0.221 ± 0.011 and 460.9 ± 35.5 mm2.s-1 respectively; at 3T MRI, FA and MD were 0.216 ± 0.01 and 480.1 ± 36.1 mm2.s-1 respectively, which may be considered as normal values for mobile lumbar spine nerve roots, independently of intersomatic space level (p = 0.06) and nerve root portion (p = 0.08) or magnetic field (p = 0.06). CONCLUSION: Normal FA and MD values can be measured along lumbar mobile spine nerve roots in healthy subjects. These values were not dependent on intersomatic space level, side or anatomical portion of the nerve root or magnetic field.

Clinical relevance of diffusion tensor imaging parameters in lumbar disco-radicular conflict.

PURPOSE: To measure the fractional anisotropy (FA) and the mean diffusivity (MD) values of L4, L5 and S1 nerve roots using diffusion tensor imaging (DTI) and to correlate them with four different clinical patterns. PATIENTS AND METHODS: Fifty-six human participants were prospectively included and divided between four groups: healthy subjects, patients with clinical symptomatic nerve root pain with and without anatomical discoradicular conflict and patients with incidental anatomical discoradicular conflict seen on magnetic resonance imaging (MRI). MRI protocol included anatomical sequences (sagittal T1- and T2-weighted, axial T2-weighted) and a 25 directions DTI sequence. FA and MD values were measured in consensus by two readers and compared between the four groups. RESULTS: Mean FA and MD values were significantly different for patients with clinically symptomatic nerve root pain (n=27) both with (n=16) (FA=0.187±0.015; MD=510±40) and without (n=11) (FA=0.193±0.011; MD=490±30.5) anatomical discoradicular conflict compared to healthy subjects (n=29) (FA=0.221±0.011; MD=460.9±35.5) including 2 subjects with incidental anatomical discoradicular conflict (FA=0.211±0.013; MD=450.8±41.2) on MRI (P=0.003). CONCLUSION: Measurement of FA and MD values of L4, L5 and S1 nerve roots using DTI could be useful in lumbar nerve root pain assessment. Further studies with different image processing methods are needed.

Axial osseous lesions mimicking disseminated metastases, a report of osseous mastocytosis.

This article reports a case of osseous mastocytosis, a relatively rare pathology that shows nonspecific osteolytic and osteoblastic bone lesions on CT. As metastatic disease is the most frequent pathology that results in incidentally discovered diffuse osteoblastic lesions, biopsy should be performed in case of doubt.