AJNR. American journal of neuroradiology
-
AJNR Am J Neuroradiol · Sep 1990
Case ReportsDiffusion-weighted MR imaging of the brain: value of differentiating between extraaxial cysts and epidermoid tumors.
This study demonstrates the use of diffusion-weighted MR imaging in improving the specificity of the diagnosis of extraaxial brain tumors. Three surgically proved lesions (one arachnoid cyst and two epidermoid tumors) and two nonsurgically proved lesions (arachnoid and ependymal cysts) were evaluated with T1- and T2-weighted spin-echo studies followed by intravoxel incoherent motion (IVIM) MR imaging. The IVIM images of the lesions were displayed as an apparent diffusion coefficient (ADC) image obtained at 0.65 G/cm (maximum gradient b value = 100 sec/mm2) and compared with external oil and water phantoms. ⋯ Cisternal CSF demonstrated uniformly high ADC, primarily because of bulk flow, which enhanced image contrast. Improved delineation of postsurgical changes was also possible. Our preliminary results show that diffusion-weighted MR imaging can be useful in distinguishing between arachnoid cysts and epidermoid tumors.
-
AJNR Am J Neuroradiol · Sep 1990
Case ReportsContrast-enhanced MR images in patients with meningioma: importance of enhancement of the dura adjacent to the tumor.
Linear enhancement (flare sign) along the dura mater that was continuous with or emanated from the dural margin of meningiomas was frequently observed on contrast-enhanced MR images obtained in 18 patients with intracranial meningiomas (surgically proved). Preoperative MR studies obtained at 1.5 T after administration of gadopentetate dimeglumine were reviewed retrospectively to determine the clinical significance of this sign. Thirteen (72%) of the 18 meningiomas exhibited the finding adjacent to the dural attachments. ⋯ Three specimens of the dura adjacent to the tumor in different patients with this finding revealed proliferation of connective tissues abounding with vessels along the dura without definite tumor invasion. The flare sign is thought to be a common finding of meningiomas on contrast-enhanced MR images obtained with high-resolution sequences, and it is observable without tumor invasion. This sign in the cerebellopontine angle should not be misinterpreted as enhancement of acoustic schwannomas.
-
Three infants with vein of Galen malformations, all presenting with congestive heart failure, underwent a total of five embolization procedures that employed a percutaneous transfemoral venous approach to catheterize the vein of Galen. In one instance, direct retrograde catheterization of feeding arterial pedicles to the vein of Galen and embolization of the fistulous connections was achieved via this route. The indications for transfemoral venous treatment included persistent symptoms despite transarterial and transtorcular embolization in one patient, an unsuccessful transarterial embolization attempt (complicated by catheter fracture) in another, and the inadvisability of transarterial embolization because of an excessive number of feeding arteries in a third. ⋯ All three patients were stable after clinical follow-ups (9-12 months). The transvenous route to the vein of Galen can be undertaken from a transfemoral approach, obviating surgical exposure of the torcular Herophili. In addition, we introduce the concept of direct retrograde catheterization of the feeding arteries to the vein of Galen malformation by a transfemoral venous approach, a procedure that has not been reported previously.
-
AJNR Am J Neuroradiol · Jan 1990
Comparative StudyGd-DTPA-enhanced MR imaging of the brain in patients with meningitis: comparison with CT.
Plain and Gd-DTPA-enhanced MR images of the brain were obtained in 18 consecutive patients with meningitis (eight with tuberculous, five with bacterial, three with viral, and two with fungal infections); the MR images were compared with CT scans. MR images were obtained on a 2.0-T superconducting unit with both T1- and T2-weighted pulse sequences before injection and with a T1-weighted sequence after injection of Gd-DTPA (0.1 mmol/kg) in all patients. In tuberculous meningitis, MR imaging depicted ischemia/infarct, hemorrhagic infarct of basal ganglia, meningeal enhancement at either basal cistern or convexity surface of brain, and associated small granulomas in a few more patients than CT did. ⋯ Although the plain MR images, both T1- and T2-weighted, were the most sensitive in delineating ischemia/infarct, hemorrhage, and edema, they were not as specific as Gd-DTPA-enhanced T1-weighted images and postcontrast CT scans in defining the active inflammatory process of the meninges and focal lesions precisely. We conclude that if Gd-DTPA is used, MR imaging appears to be superior to CT in the evaluation of patients with suspected meningitis. Precontrast MR is needed to delineate ischemia/infarct, edema, and subacute hemorrhage.
-
AJNR Am J Neuroradiol · Sep 1989
Topography and identification of the inferior precentral sulcus in MR imaging.
Sagittal MR imaging was used to investigate cerebral sulci bordering the functionally important areas on the lateral suprasylvian surface. The aim of the study was to identify characteristic relationships of the inferior precentral sulcus to nearby sulci and gyri. MR findings in 20 healthy volunteers were compared with those in 62 intact postmortem hemispheres. ⋯ Most frequently, the inferior precentral sulcus is the sulcus posterior to the anterior ascending sylvian ramus (95% in the MR study, 87% in the anatomic study). Occasionally, an additional sulcus is interposed (5%, 10%), or an ascending ramus is absent (0%, 3%). Identification of these landmarks is important for the exact preoperative localization of cortical lesions as well as for the intraoperative interpretation of individual sulcus patterns.