Search

SUMMARY: We performed a detailed neuroimaging study in a patient with Parry-Romberg syndrome. Proton MR spectroscopy demonstrated normal spectral patterns, though conventional MR imaging revealed high-intensity areas in the entire white matter in the left hemisphere. Single-photon emission tomography showed increased perfusion in the cortex of the affected hemisphere. Pyramidal tracts and optic radiations were preserved on diffusion tensor tractography. We will correlate these neuroimaging findings with normal psychomotor development in our patient.

Summary: High-resolution MR imaging of the inner ear with a heavily T2-weighted 3D fast spin-echo sequence has been performed successfully at 1.5 T. However, at 3 T, the longer T1 time of CSF necessitates a longer TR, resulting in significantly prolonged imaging times. In this study, the fast recovery 3D fast spin-echo sequence, which permits the TR to be reduced while maintaining T2 contrast, was optimized at 3 T for imaging of the inner ear. The optimized sequence parameters are as follows: 1500/294 (TR/TE); echo spacing, 18.1 ms; bandwidth, 38 kHz at 512 readout; and imaging time, 13 minutes.

BACKGROUND AND PURPOSE: MR cisternography has been used as the noninvasive screening tool of the cerebellopontine angle. The purpose of this study was to directly compare two currently dominant types of sequences for heavily T2-weighted MR cisternography. METHODS: Three-dimensional fast asymmetric spin-echo (3D-FASE) sequences, which are 3D half-Fourier rapid acquisition with relaxation enhancement and 3D constructive interference in the steady-state (3D-CISS) sequences, were compared on a clinical 1.5-T MR unit using the same scan times. In five healthy volunteers, the contrast-to-noise ratio (C/N) between CSF and the cerebellum was measured at three locations. Then, for qualitative analysis, the quality of the labyrinth was scored on the original source multiplanar reformatted images, the virtual endoscopic images, and the maximum intensity projection (MIP) images. In 20 consecutive patients with suspected cerebellopontine angle tumors, visualization of the tumors was evaluated using 3D contrast-enhanced spoiled gradient-echo imaging as the standard of reference. RESULTS: Both sequences showed comparable mean C/N values; however, in qualitative analysis, the scores for 3D-CISS on the source, virtual endoscopic, and MIP images were significantly lower than those on the images obtained with 3D-FASE, owing to more prominent flow and magnetic susceptibility artifacts on the 3D-CISS sequences. In all subjects, discontinuity of the semicircular canals was seen on the virtual endoscopic and MIP images obtained with 3D-CISS, owing to susceptibility artifacts, but not on those obtained with 3D-FASE. All 12 tumors were detected by both sequences, but 3D-CISS gave one false-positive result. CONCLUSION: 3D-FASE is considered the method of choice because artifacts are reduced and specificity is increased.

BACKGROUND AND PURPOSE: In enlarged endolymphatic duct (EED) and sac (EES) syndrome, deformity of the EED and EES is congenital; however, hearing loss is acquired. To investigate the pathophysiology of progressive sensorineural hearing loss in EED and EES syndrome, we measured the volume of the EED and EES, the diameter of the EED and EES, the area of the cochlear modiolus, and the signal intensity of the EES and compared our findings against degree of hearing loss. METHODS: Thin-section MR images of 33 ears in 17 patients with EED and EES syndrome were studied. All studies were obtained on a 1.5-T MR unit using a quadrature surface phased-array coil. Heavily T2-weighted 3D fast asymmetric spin-echo images were obtained with a voxel size of 0.3 × 0.3 × 0.8 mm without zero-fill interpolation. Two radiologists traced the areas of the EED and EES manually, and the volume was calculated. The area of the cochlear modiolus, diameter of the EED and EES, and signal intensity of the EES were also measured by drawing regions of interest manually. The signal intensity ratio of EES/CSF was calculated. These measured values were compared against audiographic data, and the degree of linear correlation was determined. RESULTS: The volume of the EED and EES, the area of the modiolus, the diameter of the EED and EES, and the signal intensity of the EES did not show significant correlation with degree of hearing loss. CONCLUSION: These findings suggest that there is a microscopic area of damage or fragility in the inner ear not visible even with thin-section heavily T2-weighted MR imaging.

Eight cases of clinically diagnosed sleep apnea syndrome (SAS) and two normal volunteers were studied with low field MR fluoroscopy in order to monitor the waking and sleeping status of the upper airway. MR fluoroscopy revealed that only the sleeping patients showed occlusions of the upper airway. This technique provided us with useful information about the level, frequency and duration of occlusion in each case. Four of the eight patients demonstrated simple retropalatal occlusion, whereas the other four demonstrated mixed retropalatal and retropalato-retroglossal occlusion. Thus long-time monitoring, which is only possible with MR fluoroscopy, is needed to appreciate the complex nature of the disease. In addition, the comfortable surroundings and low noise level provided by the low field enabled physiological study to be performed without any tranquilizers in most of the patients, which is again only possible with MR fluoroscopy. MR fluoroscopy may become a tool of great clinical value, providing much important information for disease evaluation and treatment selection.