Venous architecture of cerebral hemispheric white matter and comments on pathogenesis of medullary venous and other cerebral vascular malformations.

The parenchymal veins, especially the deep medullary veins, of the cerebral hemispheres were studied in detail by analyzing the stereoroentgenograms of multiple brain slices of postmortem injected brain specimens (injected into the internal carotid arteries in 17 cases and into the jugular veins in 12 cases). The presence of four zones--the first (or outer), the second (or candelabra), the third (or palmate) and the fourth (or subependymal) zone--of venous convergence was confirmed within the centrum semiovale, particularly in the frontoparietal area. Other venous convergences such as those related to the optic radiation in the para-atrial area were also found. Arterial branching zones were also observed in the areas similar to those of the medullary veins. It appears that these converging zones are created by rapidly growing crossing nerve fiber tracts, i.e., projection, commissural, and association fibers which grow rapidly during intrauterine and postnatal life. Pathogenesis of medullary venous malformation is also discussed from anatomical viewpoint, venoarchitecture of the pial, parenchymal, and subependymal veins and of the dural venous sinuses. The possibility of a similar mechanism (partial, mild, repetitive venoocclusive disease developing over a long period with fluctuating venous pressure) leading to formation of most (if not all) cases of medullary venous malformation and in some, if not many, cases of cerebral vascular malformations [aside from gene abnormality (chromosome 7) in familial cavernous angiomatosis, particularly in Hispanic American or other familial hereditary conditions] has been postulated.

Pantopaque simulating thrombosed intracranial aneurysms on MRI.

A patient is presented in whom iophendylate (Pantopaque) within the basal cisterns closely resembled the appearance on MRI of thrombosed aneurysms of the middle cerebral arteries. The sometimes subtle differences between the appearances on MRI of Pantopaque and aneurysmal clot are discussed to permit accurate diagnosis without resorting to more invasive diagnostic tests, such as cerebral angiography.

Predictive value of balloon test occlusion of the internal carotid artery.

Balloon test occlusion (BTO) of the internal carotid artery (ICA) is used in conjunction with single-photon emission computed tomography (SPECT) imaging to assess the cerebrovascular collateral reserve prior to surgical manipulation of the artery. The present report reviews 56 consecutive patients with tumors or vascular lesions at the base of the skull who underwent BTO and subsequent treatment on that basis within a 3-year period. Four patients underwent carotid sacrifice, since they tolerated the BTO and had normal SPECT imaging. Postoperatively, one patient had patchy infarcts in the frontal lobe, another a middle cerebral artery territory infarction, a third had a lacunar infarct, and the fourth had an impending stroke and was treated with an emergent revascularization procedure. There were 15 patients who underwent saphenous vein bypass grafting, of these there were three graft occlusions, one of which resulted in an infarction. There were two other infarctions due to technical difficulties, one being related to the revascularization procedure. Based on these results, we suggest that passing BTO with a normal SPECT study does not necessarily indicate that the patient is immune to stroke following carotid sacrifice. Revascularization should be considered, when ICA sacrifice is deemed necessary to treat the pathologic condition adequately, to minimize the likelihood of a stroke.

MRI abnormalities in Creutzfeldt-Jakob disease.

Two patients with biopsy-proven Creutzfeldt-Jakob disease had MRI studies that revealed increased signal in the basal ganglia on T-2 weighted images, suggesting that MRI can be a useful diagnostic instrument in Creutzfeldt-Jakob disease.

Common tumors of the parapharyngeal space: refined imaging diagnosis.

Computed tomographic (CT) scans and magnetic resonance (MR) images in 103 patients with either a deep-lobe parotid tumor extending into the parapharyngeal space, a minor salivary gland tumor, a neuroma, or a paraganglioma were reviewed. The parotid or extraparotid nature of these masses was established by identifying a fat plane between the mass and the parotid gland. This was more reliably accomplished with MR imaging than with CT. Although dynamic CT allowed identification of the glomus tumors, MR imaging also permitted diagnosis of these lesions. The inherent CT and MR imaging characteristics of most of the neuromas and minor salivary gland tumors were indistinguishable. However, the neuromas tended to displace the internal carotid artery anteriorly, whereas the salivary lesions displaced this vessel posteriorly. This artery was better identified on MR images than on CT scans. Thus, these lesions, which are the four most common primary parapharyngeal space tumors, can be distinguished on MR images by evaluating not only their inherent signal characteristics but also the surrounding fat planes and any displacement of the internal carotid artery.

The use of magnetic resonance and computed tomography in the management of a patient with intrasinus hemorrhage.

The judicious use of computed tomography and magnetic resonance imaging in a critically ill patient with leukemia is discussed to demonstrate how a rapid and accurate diagnosis of intrasinus hemorrhage was established, thereby avoiding an unnecessary invasive procedure in this high-risk patient. In this clinical setting, a brief T1-weighted study distinguished between blood and infection.

Benign and malignant parotid pleomorphic adenomas: CT and MR studies.

Parotid pleomorphic adenomas are usually benign, solitary, ovoid masses. Occasionally, these tumors may be highly lobulated and clinically mimic multiple lesions. Actual multiple benign mixed tumors are rare as are malignancies that occur in these pleomorphic adenomas. Of these malignancies, the most common type is the carcinoma ex pleomorphic adenoma. Two patients are presented, one of whom had a markedly lobulated benign mixed tumor and the other patient had an ex pleomorphic malignancy associated with multiple benign mixed tumors. Both cases are documented with CT and magnetic resonance studies. The relative merits of these modalities are discussed as they apply to these parotid masses.

Paget disease of the calvaria and facial bones with an osteosarcoma of the maxilla: CT and MR findings.

The CT and magnetic resonance (MR) findings of Paget disease of the calvaria and facial bones are described and compared with one another. The sites of dense, woven bone, myeloid marrow, and background Paget matrix can be clearly identified. A rare case of Paget sarcoma (osteogenic sarcoma) of the facial bones is also presented. The distinction between this sarcoma and the Paget bone was clearer on CT than on MR. This presumably is because the bone is directly seen on CT and only indirectly imaged on MR.

Periventricular high signal lesions and signal void on magnetic resonance imaging in hydrocephalus. Diagnostic and prognostic significance.

The presence of periventricular high signal lesions and ventricular signal void was tabulated and compared in three groups: patients with unshunted hydrocephalus (n = 24), cerebral atrophy (n = 14), and a subgroup of treated hydrocephalus subjects studied both pre- and post-shunting (n = 6). We found that T2 high signal lesions and ventricular signal void are common in both hydrocephalus and atrophy and are of no value in distinguishing between the two. The pre-treatment presence or absence of periventricular high signal lesions and signal void were of no use in predicting the clinical outcome of shunting in hydrocephalus.