We investigated the efficacy of magnetic resonance imaging (MRI) in the detection and delineation of acute hemorrhagic cerebral infarction and evaluated the role of gradient-echo imaging in these patients. This study was performed prospectively. Entry criteria were: (1) Clinical evidence of acute supratentorial infarction later confirmed by at least one imaging study, and (2) unenhanced computed tomography (CT) and MRI scans performed within 72 hours of ictus. The first 50 patients who met these criteria were included. Comparison of CT and spin-echo (SE) and gradient-echo (GE) MRI at 0.6 T for the visualization of infarction and for the detection or exclusion of hemorrhage were done. There were no cases in which CT was superior to MRI for the diagnosis of either bland or hemorrhagic infarction. All 50 infarcts were detected on long TR SE MRI and 30/50 on GE scans. Eighteen infarcts were judged to be hemorrhagic on the basis of well-established CT and MRI criteria. In all these cases, hemorrhage was most obvious on GE scans as focal areas of marked hypointensity, including 10 cases in which SE MRI and CT demonstrated subtle, equivocal, or no evidence of hemorrhage. In addition, GE MRI allowed for the exclusion of hemorrhage in five cases with equivocal findings of hemorrhage on long TR SE MRI. GE MRI is a valuable adjunct to SE sequences for the detection or exclusion of hemorrhage in acute infarcts with equivocal or mild intensity changes on SE MRI. With further improvements in fast-scanning techniques and a greater understanding of the pathophysiology and clinical implications of hemorrhagic infarction, it may be possible to replace CT with a combination of SE and GE MRI as the primary imaging modality in the evaluation of acute infarction.

Acute Disease↗

PubMedDate not supplied

The neuroimaging features of the cardiolipin antibody syndrome.

The purpose of our study was to define the neuroimaging features of the cardiolipin antibody syndrome. Thirty-eight patients with elevated anticardiolipin antibody titers were studied with magnetic resonance imaging or computed tomography or both. Two patients underwent cerebral angiography. All patients had recurrent transient ischemic attacks, amaurosis, or strokes. One patient had normal imaging findings. The remaining patients had a combination of infarction and atrophy. Focal infarcts, the most common finding, were seen in 32 patients. Cerebral atrophy was seen in 26 patients and was the only radiographic finding in 5. Angiography demonstrated dramatic abnormalities in the distal portions of the anterior and posterior circulations, with multiple stenosis and occlusions and extensive pial and transdural collateral networks. The cardiolipin antibody syndrome should be suspected in young patients with transient ischemic attacks or strokes in the absence of the usual risk factors for cerebrovascular disease. The presence of raised anticardiolipin antibody titers or the cardiolipin antibody syndrome in patients with lupus, in those with other connective tissue diseases, and in patients without overt manifestations of an autoimmune disorder should be viewed as a risk factor for future ischemic cerebrovascular events. Further understanding of the precise role of these antibodies in the pathogenesis of vascular thrombosis may lead to a better understanding of the mechanisms underlying certain forms of stroke.

Adolescent↗

PubMedDate not supplied

Computed tomography of nontuberculous spinal infection.

The CT findings in 16 patients with nontuberculous spinal infections were reviewed. The specificity of certain CT features as well as the usefulness of intravenous contrast medium administration are discussed. The associated clinical presentations and predisposing factors are outlined. Emphasis is placed on a combined clinical, radiographic approach in facilitating an early diagnosis.

Abscess↗

PubMedDate not supplied

MR imaging of acute intracranial hemorrhage: findings on sequential spin-echo and gradient-echo images in a dog model.

Seven intraparenchymal hematomas (four venous and three arterial) were placed in the brains of six dogs in order to study the MR appearance of acute hemorrhage and to evaluate the effects of several variables on the signal intensity of the hematoma. MR imaging at 0.6 and 1.5 T was performed by using standard short and long TR spin-echo and low-flip-angle gradient-echo sequences. Sequential examinations were performed during the first week following hematoma creation. MR findings were compared with CT and postmortem examinations. Three patterns of signal intensity were observed, which varied according to the size (small vs large) and location (parenchymal vs intraventricular) of the hematomas. The small parenchymal hematomas did not undergo evolutionary changes. On short TR scans they were isointense at both field strengths, and therefore not detectable; on long TR scans these hematomas were of variable intensity at 1.5 T and were hyperintense at 0.6 T. On gradient-echo scans, they were hypointense at all times at both field strengths. The large parenchymal hematomas underwent evolutionary changes typical of those seen in clinical imaging. On short TR scans they were initially isointense and became hyperintense 1-3 days later. Long TR scans demonstrated initial hyperintensity, followed by the development of hypointensity within 12 hr in the venous hematomas and within 60 hr in the arterial hematoma. The intensity changes on long TR scans were seen at both 0.6 and 1.5 T, but occurred sooner and to a greater degree at 1.5 T. Gradient-echo imaging of these large lesions demonstrated hypointensity at all times at both field strengths. The intraventricular hemorrhages demonstrated more rapid development of hyperintensity on short TR scans and slower and less pronounced development of hypointensity on long TR scans compared with the parenchymal clots in the same animal. Gradient-echo imaging of the intraventricular hemorrhages demonstrated hypointensity at all times at both field strengths. A multifactorial hypothesis is proposed to explain the differences in intensity between venous, arterial, and intraventricular blood. Gradient-echo sequences should prove to be highly useful in detecting and delineating hemorrhages and are recommended for the MR protocol of patients with acute neurologic ictus and suspected hemorrhage.

Acute Disease↗

PubMedDate not supplied

Detection of acute intracerebral hemorrhage on MR imaging: ineffectiveness of prolonged interecho interval pulse sequences.

MR imaging at 0.6 T was performed in 22 patients with acute (less than 7 days) intracranial hemorrhage to determine the efficacy of prolongation of the interecho interval, which has been demonstrated to enhance T2 shortening in vitro, as a method to improve the detection of hemorrhage in clinical imaging. The protocol included 750/33 (TR/TE), 2150/60,120 (short interecho interval of 60 msec), and 2150/120 (long interecho interval of 120 msec) sequences. Visual comparisons of the 2150/120 images obtained with the short and long interecho intervals demonstrated no difference in the degree of hypointensity in 21 of 22 cases. Quantitative comparisons demonstrated no statistically significant difference in the degree of maximal hypointensity, in the ease of detectability of hypointensity, or in the overall image contrast in 16 of 22 cases. We conclude that prolongation of the interecho interval is not a clinically useful technique to improve the detection of acute hemorrhage.

Acute Disease↗