Biomedical subjects
Publications and source records attributed to D J Loes.
An 18-month-old male sustained an intra-oral injury after falling on a pen. The internal carotid artery was occluded without evident neurologic deficit. The pen tip was surgically removed from the cerebellum.
MR changes of cerebral ischemia have been shown to occur as early as 1-2 hr after vessel occlusion in experimental models of stroke. However, the MR findings in the early stages of ischemic stroke in the clinical population have not been well established. We studied 41 lesions in 39 patients in whom MR was performed within the first 24 hr after onset of ischemic symptoms. Twenty-five lesions were studied with gadopentetate dimeglumine. Vascular flow-related abnormalities, including absence of normal flow void and presence of arterial enhancement, were the earliest MR findings, detected within minutes of onset. Morphologic changes (brain swelling) on T1-weighted images without signal changes on T2-weighted images could be detected within the first few hours. Signal changes were not usually found before 8 hr on T2-weighted images or before 16 hr on T1-weighted images. In contrast to the absence of parenchymal enhancement typically found in cortical infarctions in the first 24 hr, a few lesions (including transient occlusions, partial occlusions, and isolated watershed infarctions) exhibited early, exaggerated parenchymal enhancement. We conclude that signal changes may not be reliable in detecting ischemic stroke within the first 8 hr after onset. Vascular abnormalities, when present, are the most reliable and earliest findings. Other MR findings of early ischemic stroke, including morphologic changes and early, exaggerated parenchymal enhancement, may also precede signal changes. Paramagnetic contrast administration often provides valuable information in the detection and evaluation of acute ischemia.
Eighty patients with a total of 82 ischemic lesions were examined with contrast-enhanced MR imaging 1 hr to 1 month after onset of symptoms. The studies were reviewed retrospectively to determine the presence of arterial enhancement and the patterns of parenchymal enhancement. Arterial enhancement was often detected on the initial MR examination (45%), was frequently demonstrated in cortical infarction (86%), in some cases preceded the development of signal changes on T2-weighted images, and resolved by 11 days. The presence of arterial enhancement appeared to be a better indicator of clinical severity than was the presence of proximal vessel occlusion on MR or angiographic studies. Two patterns of parenchymal enhancement were seen: progressive enhancement and early and/or intense enhancement. In patients with the progressive pattern, parenchymal enhancement on postcontrast T1-weighted images was rarely seen before 7 days, while signal abnormalities on T2-weighted images were intense during the first few days. The early and/or intense enhancement pattern was usually present within the first 3 days, approximated or exceeded the area and intensity of signal changes on T2-weighted images, and was usually associated with minimal or reversible neurologic sequelae (except when located in or near a watershed zone), suggesting a lesser degree of ischemic insult than was associated with the progressive pattern.(ABSTRACT TRUNCATED AT 250 WORDS)
Cerebral angiography in patients with nontraumatic lobar intracerebral hemorrhage may or may not uncover the underlying cause of the disorder. The CT and cerebral angiographic studies of 67 consecutive patients with nontraumatic lobar intracerebral hemorrhage were reviewed to assess the relationship between CT pattern and location of hemorrhage and the frequency of diagnostic angiographic findings. Origins of these hematomas were also determined and correlated with radiographic findings. CT revealed 26 temporal, 18 frontal, 17 parietal, three occipital, and three multiple lobar hematomas. Thirty-three patients had "pure" lobar hematomas, 12 had coexistent intraventricular hemorrhage, 12 had associated subarachnoid hemorrhage, and 10 had both intraventricular and subarachnoid hemorrhage accompanying their lobar hematomas. Angiographic findings were diagnostic in 29 cases (43%). In the presence of accompanying subarachnoid hemorrhage, angiographic findings were diagnostic in 17 (77%) of 22 patients; in its absence, angiography was diagnostic in 12 (27%) of the remaining 45 patients. Diagnostic angiograms were also more frequent in the presence of a frontal or temporal lobar hematoma than with a parietal or occipital lobar hematoma. While CT patterns do influence the frequency of diagnostic angiographic findings, cerebral angiography is recommended in all patients with otherwise unexplained nontraumatic lobar intracerebral hemorrhage.
PURPOSE: To determine the potential of proton MR spectroscopy to monitor patients with childhood-onset cerebral adrenoleukodystrophy (COCALD). METHODS: Single-voxel MR spectroscopy was performed in 16 children with COCALD (24 examinations) who had had no treatment and in 7 children (13 examinations) who had had bone marrow transplantation. RESULTS: In the untreated children with clinically active COCALD, the metabolite ratios N-acetyl-aspartate (NAA)/creatine (Cr) and NAA/choline (Ch) were decreased while Ch/Cr was increased. This trend agrees well with those reported by other researchers, although different experimental sequences and parameters were used in our study. Comparison of these ratios with those from a control group yielded significant differences in the occipital region. In the children who were clinically stable after bone marrow transplantation, the mean levels of the three ratios were between those of the control subjects and the patients with untreated COCALD: the differences in these ratios approached significance. In patients who had been monitored periodically, MR spectroscopy metabolite ratios correlated well with the dementia rating score, reflecting clinical status. CONCLUSION: There is good correlation between MR spectroscopy metabolite ratios and a patient's clinical status. MR spectroscopy appears to be a useful, noninvasive tool to monitor patients with adrenoleukodystrophy, and it increases the overall sensitivity of MR techniques in clinical applications.