P. Schubeus

“Menigeal sign”: a characteristic finding of meningiomas on contrast-enhanced MR images

SummaryIn meningiomas, a flat, contrast-enhancing, probably dural structure adjacent to the tumor can occasionally be observed on Gadolinium-DTPA enhanced MR images. This so called “meningeal sign” was evaluated with respect to the differential diagnosis of meningiomas in MR imaging. The study included 29 patients with intracranial meningiomas and 24 patients with non-meningeal brain tumors. In all meningiomas, MR studies included T2-weighted as well as unenhanced and Gadolinium-DTPA-enhanced T1-weighted images. In all nonmeningeal tumors, Gd-DTPA-enhanced MR images were available. All images were evaluated with respect to the presence of the “meningeal sign”. In meningiomas, a “meningeal sign” was seen in 15/29 cases on Gadolinium-DTPA-enhanced images. No abnormalities corresponding to the areas of contrast enhancement were found on unenhanced T2- and T1-weighted MR images. In nonmeningeal tumors only 2/24 cases showed a “meningeal sign”. In conclusion, with a sensitivity of 52% and a specificity of 92%, the demonstration of the “meningeal sign” improved the differential diagnosis of intracranial meningiomas in contrast-enhanced MR imaging.

Intracranial meningiomas: How frequent are indicative findings in CT and MRI?

SummaryFrequencies of CT and MRI findings characteristic of meningiomas were compared in 50 cases. Plain and contrast enhanced examinations with CT and MRI were evaluated retrospectively regarding 12 criteria known to be indicative of the diagnosis of meningiomas. CT proved to be superior in demonstrating calcifications and a typical tumor density. On the other hand, MRI was better suited for identifying the extraaxial location of tumors, the broad contact of tumors to the meninges, tumor capsules and meningeal contrast enhancement adjacent to the tumor. Both methods provided nearly equal results in demonstrating mass effects, hyperostoses, intensive and homogeneous contrast enhancement, and smooth tumor contours after contrast administration. On the whole, neither of the two methods demonstrated a universal superiority for the diagnosis of intracranial meningiomas. Rather, each method displayed distinct advantages.

Spinal cord cavities: differential-diagnostic criteria in magnetic resonance imaging

MRI examinations of 30 patients with idiopathic syringomyelia and 10 patients with cavities associated with an intramedullary neoplasm were evaluated with respect to typical MRI features in both groups. All tumor-associated cases resembled the idiopathic syringomyelias in some portions of the cavity. At the tumor site, however, tumor-associated cases demonstrated typical findings: the cavities showed abrupt changes of diameter (10/10) and position (8/10) and the surrounding spinal cord demonstrated an uneven thickness (10/10), an increased signal intensity on T2-weighted images (10/10) and pathological contrast enhancement (7/7). Displacement of cerebellar tonsils below the level of the foramen magnum (21/30) and enlargement of the spinal canal (7/29) were characteristic features of idiopathic cases. In conclusion, MRI provides valuable criteria to differentiate between idiopathic and tumor-associated cavities.

Time-reduced T2-weighted celebral MRI with optimized flip angles

This study was set up to see whether lowering the flip angle in proton density- and T2-weighted double-spin echo sequences allows for shortening of repetition time (TR) and imaging time without significant change of image quality. Ten patients with celebral white matter lesions were investigated with an 1.5 T MR scanner using a conventional long- TR double-spin echo sequence (TR = 2500 ms, TE = 15 and 70 ms) and reduced-TR double-spin echo sequences (TR = 1900 ms, TE = 15 and 70 ms) at flip angles of 90°, 80°, 70°, 60°, and 50°. Lowering the flip angle resulted in less T1-contrast and a relative increase of T2-contrast. At a flip angle of 70°, contrast-to noise ratios (NNRs) between lesions and brain, as well as image artifacts of the reduced-TR sequence (CNR: 22.4) were similar to the conventional long-TR sequence (CNR:21.1), while imaging time was shortened by about 25%.

Gadolinium DTPA-enhanced MRI of degenerative cervical spine disease*

Thirty-two patients with 30 disc herniations and 5 bony stenoses were investigated together with 5 control subjects, using plain and contrast-enhanced Magnetic resonance imaging. Compared with the control group, additional non-enhancing epidural tissue was found in all patients. The enhancing epidural structures demostrated characteristics change. Compared with plain images, disease definition was improved in 7 of 35 cases after contrast administration. This was especially true for lateral and intraforaminal disc herniations, whereas no diagnostic benefit was seen in cases of posterior and posterolateral herniations or bony changes.