Cerebral magnetic resonance imaging of liver cirrhosis patients

Thirty-two patients with liver cirrhosis underwent cerebral magnetic resonance imaging (MRI) to evaluate clinical and subclinical portal-systemic encephalopathy (PSE). Symmetrically hyperintense globus pallidi were observed on T1-weighted images in all 11 patients with PSE and in 15 of the 21 patients with PSE. This abnormality was classified as grade I (bilateral globus pallidi with mild to moderate hyperintensity relative to white matter), and grade II (marked hyperintensity bilaterally in the globus pallidi with mildly increased signal intensities in the surrounding structures). Portal-systemic collateral vessels were demonstrated in 23 of 24 patients who underwent abdominal angiography. In 18 of the 19 patients with abnormal MRI, collateral vessels were supplied by the superior mesenteric vein with or without the splenic vein, including four patients with collaterals which were less than 10 mm in diameter. We concluded that hyperintense globus pallidi on T1-weighted images are significant manifestations of clinical PSE. When portal-systemic collaterals supplied by the superior mesenteric vein are observed, even if they are of small diameter, cerebral MRI should be performed to evaluate for subclinical PSE.

MR imaging compared with CT, angiography, and myelography supplemented with CT in the diagnosis of spinal tumors

To clarify the significance of MR imaging and the present status of CT, angiography, and myelography supplemented by CT (M-CTM), the radiological findings of 50 spinal tumors were reviewed and analyzed. MR imaging was most effective for visualizing morphological features such as the margins and/or inner structures of the tumors. CT was also effective for imaging "dumbbell" neurinomas and extradural tumors. Angiography was necessary in one hemangioblastoma and in cervical extradural tumors. M-CTM visualized the morphology of intradural extramedullary tumors and extradural tumors, but provided no new information in most of these cases. It was concluded that when using MR the indications for CT, angiography, and M-CTM are limited and that CT or angiography should be performed only in selected cases. M-CTM appeared to be unnecessary.

[Contrast-enhanced MR imaging using double doses of gadolinium-DTPA in evaluating brain and spinal diseases]

Forty-one lesions of intracranial and spinal diseases underwent magnetic resonance (MR) imaging at both standard-dose (0.1 mmol/kg) and double-dose (0.2 mmol/kg) levels of gadolinium (Gd)-DTPA in order to reassess the optimal dose of Gd-DTPA. Each patient received an initial injection of 0.1 mmol/kg and an additional dose of 0.1 mmol/kg 5 min later. In quantitative analysis of contrast enhancement ratios of the enhancing part of the lesion, choroid plexus, cavernous sinus and pituitary stalk were significantly (P < 0.01) increased in double-dose studies. For visual comparison, we defined delineation as the extent to which the lesion may be defined; detectability was defined as the ability to visualize the lesion. With respect to delineation, double-dose studies were superior to standard-dose studies in nine of 20 intraaxial tumor (four of eight malignant gliomas, three of eight benign gliomas and two of four metastatic brain tumors) and five of six cerebral infarcts. The detectability of the lesion was improved in four cases (one astrocytoma, two metastatic brain tumors and one cerebral infarct) in double-dose studies. It was concluded that contrast-enhanced MR imaging using double doses of Gd-DTPA may be useful in the detection and evaluation of the extent of intraaxial lesions enhanced by Gd-DTPA.

[Cerebral MR imaging in patients with primary biliary cirrhosis]

Five patients with primary biliary cirrhosis (PBC) underwent cerebral magnetic resonance (MR) imaging to evaluate subclinical hepatocerebral degeneration. All patients were neurologically asymptomatic, but three of the five patients had symptoms such as jaundice and itching. Symmetrically hyperintense globus pallidi were observed on T1-weighted images in four of the five patients. One remaining patient who had normal MR images was an asymptomatic fresh case. Patients with markedly hyperintense globus pallidi also had mildly increased signal intensities in the surrounding structures. On proton-density- and T2-weighted images, there were no abnormal signals in the globus pallidi any of the patients. Portal-systemic collateral vessels were demonstrated in three of the four patients with abnormal MR images. The mechanisms by which T1-shortening of the globus pallidi occurs remains obscure. We believe that both portal-systemic collaterals and cholestasis play a prominent role in the cause of cerebral abnormalities on T1-weighted images.

Solitary choroid plexus lipomas: CT and MR appearance

Using MR imaging, the authors detected 23 cases of intracranial lipomas, among which were three cases of solitary choroid plexus lipomas. All the lipomas were located in the choroid plexus at the trigone. One of the three solitary choroid plexus lipomas was very small and could not be detected using CT. The authors believe that solitary choroid plexus lipomas are not as rare as was previously thought.

MRI of intradural-extramedullary spinal neurinomas and meningiomas

The magnetic resonance images of 16 patients with intradural-extramedullary spinal tumors, consisting of 11 neurinomas and five meningiomas were reviewed. The neurinomas appeared hypointense compared to the spinal cord on unenhanced T1-weighted images (T1WI) in nine of 11 patients, and hyperintense on T2-weighted images (T2WI) in nine of 11 patients. Neural foraminal extension was present in two cases. All 10 neurinomas were markedly enhanced; six of them exhibited ring-like enhancement on Gadolinium-DTPA (Gd-DTPA)-enhanced T1WI. The meningiomas appeared isointense on unenhanced T1WI in four of five patients and on T2WI in three of four patients. Three meningiomas showed moderate homogeneous contrast enhancement after the intravenous administration of Gd-DTPA. It is concluded that careful scrutiny of magnetic resonance images facilitates the differential diagnosis of spinal neurinomas and meningiomas.

MRI of dorsal mesencephalic lipomas

We detected 23 intracranial lipomas using MRI. Among them were nine pericallosal lipomas, six lipomas at the dorsal surface of the midbrain, and eight in other locations. In this paper, six lipomas at the dorsal surface of the midbrain were analyzed. Five of these lipomas were in the quadrigeminal cistern and one in the left-sided quadrigeminal cistern. Excluding the smallest lipoma, five of the six lipomas had irregular margins and were broadly based on the surface of the midbrain. In these five cases, deformities of the brain parenchyma were observed adjacent to the lipomas. A mildly dilated ventricular system was observed in one of the largest lipomas in a quadrigeminal cistern. Based on their characteristic shapes and locations, we termed them "dorsal mesencephalic lipomas." Thus, the two preferential sites of intracranial lipomas were pericallosal and dorsal mesencephalic.

Portal-systemic encephalopathy: report of a case with unusual MR findings

A case of subclinical portal-systemic encephalopathy with unusual MR findings is described. The basal ganglia and cerebral white matter were diffusely hyperintense on T1-weighted images. No similar cases have been previously described in the literature.

Olivary degeneration after cerebellar or brain stem haemorrhage: MRI

Magnetic resonance (MR) images of seven patients with olivary degeneration caused by cerebellar or brain stem haemorrhages were reviewed. In four patients with cerebellar haemorrhage, old haematomas were identified as being located in the dentate nucleus; the contralateral inferior olivary nuclei were hyperintense on proton-density- and T2-weighted images. In two patients with pontine haemorrhages, the old haematomas were in the tegmentum and the ipsilateral inferior olivary nuclei, which were hyperintense. In one case of midbrain haemorrhage, the inferior olivary nuclei were hyperintense bilaterally. The briefest interval from the ictus to MRI was 2 months. Hypertrophic olivary nuclei were observed only at least 4 months after the ictus. Olivary degeneration after cerebellar or brain stem haemorrhage should not be confused with ischaemic, neoplastic, or other primary pathological conditions of the medulla.

[MR imaging of pericallosal lipomas]

Eight cases of pericallosal lipomas were studied by MR imaging at 1.5 Tesla. All were located around the splenium of the corpus callosum, and were classified as the curvilinear type. Corpus callosal abnormalities were detected in the six of these eight cases, and included two cases of short corpus callosum and four of thin splenium. The larger lipomas tended to have greater abnormalities of the corpus callosum. T1-weighted sagittal images were the most useful pulse sequences for diagnosing pericallosal lipomas and corpus callosal abnormalities. On review of the literature we found that the curvilinear type of pericallosal lipoma is more frequently observed by MR imaging than the tubulonodular type.

[MR imaging of stereotactic thalamotomy using radiofrequency methods]

Sixty-eight stereotactic radiofrequency (rf) thalamic lesions in 57 patients with movement disorders were evaluated by magnetic resonance (MR) imaging. Postoperative periods ranged from 5 days to 4 years and 9 months. All 68 rf lesions were clearly detected on T2-weighted images (T2WI). Changes in signal intensity on T2WI were classified into five patterns, as follows: Pattern I: lesions with three concentric zones consisting of an inner hypointense, middle hyperintense and outer hypointense zone (31 lesions); Pattern II: lesions consisting of an inner hypointense and outer hyperintense zone (4 lesions); Pattern III: lesions consisting of an inner hyperintense and outer hypointense zone (27 lesion); Pattern IV: lesions of a hyperintense area alone (2 lesions); Pattern V: lesions of a hypointense area alone (4 lesions). The outer hypointense rim in Patterns I and III is thought to represent hemosiderin deposition. The abnormal signal intensity on T2WI caused by rf ranged from 2 to 12 mm in diameter, and lesions in the late phase were smaller than lesions in the early phase.

MRI of dural carotid-cavernous fistulas. Comparisons with postcontrast CT

Ten patients with dural carotid-cavernous fistulas (CCFs) who presented with ophthalmic manifestations were studied using postcontrast computed tomography (CT), magnetic resonance imaging (MRI), and selective cerebral arteriography. The lesions of two patients were bilateral. An enlarged cavernous sinus (CS) was diagnosed in 6 of the 12 involved sides using postcontrast CT. An abnormal flow void in the CS was detectable in 11 of the 12 using MRI. A dilated superior ophthalmic vein (SOV) was demonstrated in all of the involved sides by postcontrast CT, and in 9 of the 12 by axial MRI. Thus, both postcontrast CT and MRI are relatively useful and complementary in the diagnosis of dural CCFs. Patients should be followed with selective cerebral arteriography for definitive diagnoses and for therapeutic planning.

Atypical arteriographic features of myositis ossificans circumscripta (MOC)

Earlier reports on the angiographic features of MOC concluded that there may be hypervascularity and tumor stain but no A-V shunting, pooling, or vessel amputation as a result of the lesion. However, our cases demonstrated A-V shunting in MOC, and showed that the vascularity of this lesion can closely mimic that of malignant neoplasms. Therefore, the possibility of MOC should not be excluded because of the presence of A-V shunts or "tumor vessels" in suspected MOC lesion on plain radiography. These points are underscored by the findings in two MOC patients, whose cases are described.

[MR imaging of intraocular lesions--a comparison with CT]

Thirty-two intraocular lesions were studied with magnetic resonance (MR) imaging and computed tomography (CT). These lesions included retinoblastoma (n = 11), uveal melanoma (n = 6), metastatic choroidal tumor (n = 3), choroidal hemangioma (n = 2), retinochoroiditis (n = 6) and Coats' disease (n = 4). MR imaging was superior to CT in the depiction of intraocular masses and retinal detachment. Gd-DTPA enhanced MR imaging was more useful than contrast enhanced CT in evaluating the contrast enhancement of intraocular tumors. Differential diagnosis of intraocular tumors was difficult with both MR imaging and CT. Intratumoral calcification was noticed on CT in nine cases of retinoblastoma. It was concluded that MR imaging, including contrast enhancement study, is more useful than CT in the evaluation of intraocular lesions, except for calcification, and contrast enhanced CT may be unnecessary in the diagnosis of intraocular lesions.

MR imaging and angiography of cerebral venous angiomas associated with brain tumors

MR study of 6 patients with concurrent venous angioma and brain tumor revealed that in 2 of the 6 cases, the draining vein of the venous angioma was located near to the tumor and was displaced by the tumor. Two of the 6 venous angiomas were too small to visualize prior to contrast enhancement, but could be detected following administration of Gd-DTPA. Angiography was required for definitive diagnosis of the venous angiomas. When a venous angioma is suspected or is detected incidentally, especially when very near a brain tumor, angiography should be considered before performing surgery to avoid surgical complications. Otherwise, ligation of the vein draining the venous angioma may lead to venous infarction.

Local complications in transbrachial cerebral angiography using the 4-F catheter

Local complications of cerebral angiography using the transbrachial technique were assessed. In 333 patients with cerebrovascular disease 342 catheterizations using a sheathless 4-F catheter were attempted, with 337 successes (98.5%). There were two major and five minor complications (2.1%). A massive hematoma and a pulse deficit were overcome without sequelae. The overall complication incidence was significantly higher in females (5.7%) than in males (0.4%). This procedure requires extra care in female patients.

[MR imaging of pontine infarction within 2 weeks after ictus]

Magnetic resonance (MR) images of 10 patients with pontine infarction were reviewed. A total of 17 examinations were performed on a 1.5 Tesla high-field scanner (GE) within two weeks after ictus. The infarcted area was detected by MR as early as 20 hours after stroke in one case. However, MR images obtained in two cases three and nine hours after onset were unremarkable. It is therefore suggested that follow-up study should be performed when initial MR images within 20 hours postictus are normal. T1-weighted images at four, nine and twelve days after ictus were interpreted as normal. In two of these three examinations, the infarcted areas were clearly demonstrated as hyperintense lesions on T2-weighted images. In the other examination, however, an area of mildly increased signal intensity was seen on T2-weighted images. This case suggests that the fogging effect is also observed on MR imaging and that a small pontine infarction may be overlooked during the subacute stage. Basilar artery occlusion was detected as an absence-of-flow void in three of the ten patients. In conclusion, MR imaging proved to be a relatively useful diagnostic modality for evaluating acute and subacute pontine infarctions.

MR imaging of middle cerebral artery occlusion without cerebral infarction

Magnetic resonance (MR) images of 12 patients with angiographically proven middle cerebral artery (MCA) occlusion were analyzed, retrospectively. In three of the 12 patients, cerebral infarctions related to the MCA occlusions were not evident. Two of the three patients were cases of atherosclerotic occlusion and the remaining patient had an acute thromboembolism. In all of the occluded M1 portions of the MCA the flow void was absent and there were isointense linear structures, with or without a hyperintense component in the Sylvian vallecula, on T1-weighted images. For nine of the 12 patients, the absence of flow void in the ipsilateral Sylvian fissure was evident on the T2-weighted images. Therefore, even in cases with no evidence of a cerebral infarction, the presence of flow void in the Sylvian vallecula and Sylvian fissure must be searched for in routine reviews of MR images. If MR imaging can be obtained on an emergency basis, appropriate interventional therapy may be immediately initiated.

[MR imaging of medullary infarction]

Magnetic resonance (MR) images of 20 patients with medullary infarction have been reviewed. All patients were imaged on a 1.5 Tesla high-field scanner (GE, Signa). Clinical diagnoses of these 20 patients were Wallenberg's syndrome (15), cerebellar infarct (3), right hemiparesis (1), and multiple cerebral infarcts (1). Locations of infarct were right lateral (8), right postero-lateral (2), left lateral (5), left postero-lateral (4) and left anterior (1). Associated ipsilateral cerebellar infarcts were observed in six patients. Ipsilateral vertebral artery (VA) occlusions were detected in six patients, and VA aneurysm in two. Thus, MR imaging is a pertinent diagnostic modality for evaluating medullary infarction and associated vascular diseases.

Thickened fatty filum terminale: MR imaging

MR images of four patients with a thickened filum terminale showing a fat signal are presented. There were no related symptoms and no evidence of tethering. The thickened fatty filum terminale seemed to be a developmental anomaly and without clinical significance. As the incidence of this anomaly was 0.24% in our series, knowledge of its possible presence of this anomaly is important for routine reviews of MR image.

Serial MR imaging in Creutzfeldt-Jakob disease

Serial magnetic resonance (MR) imagings of two autopsied patients with Creutzfeldt-Jakob disease (CJD) are presented. Both patients showed a dramatic progression of brain atrophy. The initial MR imagings were, however, interpreted as normal except for localized mild cortical atrophy in one patient. When a normal MR image is obtained in a demented middle-aged or aged patient, CJD may still need to be ruled out: follow up MR imaging may be useful.

Magnetic resonance imaging of intracranial venous angiomas

Magnetic resonance imagings (MRI) were made of intracranial venous angioma (six angiographically proved, four presumed). All draining veins were identified as a linear or a small round structure with a flow void. The stellate configuration was observed in seven of the ten patients. In two of the ten, the associated intraparenchymal hematoma was evident. Increased intensity of adjacent parenchyma on T2-weighted images was detected in four of ten patients, and a decreased intensity on the T1-weighted images was noted in three of eight. Thus, MRI is a pertinent diagnostic modality for evaluating intracranial venous angioma. Angiography does not seem to be required for confirmation in patients with typical MR findings.