Although conventional proton magnetic resonance imaging has increased our ability to detect brain tumors, it has not enhanced to nearly the same degree our ability to diagnose tumor type. Proton magnetic resonance spectroscopy is a safe, noninvasive means of performing biochemical analysis in vivo. Using this technique, we characterized and classified tissue from normal brains, as well as tissue from the five most common types of adult supratentorial brain tumors. These six tissue types differed in their pattern across the six metabolites measured. 'Leaving-one-out' linear discriminant analyses based on these resonance profiles correctly classified 104 of 105 spectra, and, whereas conventional preoperative clinical diagnosis misclassified 20 of 91 tumors, the linear discriminant analysis approach missed only 1. Thus, we have found that a pattern-recognition analysis of the biochemical information obtained from proton magnetic resonance spectroscopy can enable accurate, noninvasive diagnosis of the most prevalent types of supratentorial brain tumors.

Summary: Fourteen patients were studied by positron emission tomography (PET) within 48 h of onset of a hemispheric ischemic stroke and again 7 days later. After the first set of PET scans, the patients were randomized to receive either nimodipine (n = 7) or a carrier solution (n = 7) by intravenous infusion. The infusions were main tained until the end of the second PET studies. CBF, cerebral blood volume (CBV), oxygen extraction ratio (OER), CMR02, and CMRglc were measured each time. These metabolic and perfusion measurements were per formed by standard methods. A surface map of each met abolic and perfusion measurement in the cortical mantle was generated by interpolating between the available slices. The various surface maps representing the physi ological characteristics determined in the same or subse quent studies were aligned so that all data sets could be analyzed identically using an array of square regions of interest (ROIs). The functional status of each ROI was recorded at the two intervals following the cerebrovascu- 523 lar accident to characterize the evolution of the infarct, penumbra, and normal brain regions. We presumed the ischemic penumbra to be cortical regions in the proximity of the infarct and perfused at CBF values between 12 and 18 ml/loo g/min on the first PET scan, while densely isch emic regions had CBF of <12 nlllOO glmin and normally perfused brain> 18 ml/loo g/min. In the densely ischemic zone, CBF increased more in the nimodipine-treated group than in the carrier group. As well, in this region nimodipine reversed the decline in CMR02 noted in the carrier group, the difference in the changes being signif icant. In the penumbra zone, comparable trends were noted in OER and CMR02 but the difference in the changes between the two groups did not reach statistical significance. Changes in CMRglc and CBV were compa rable between the two groups in both cortical regions.

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