Figure 1. Magnetic resonance spectroscopy image obtained from a patient with stroke approximately 12 hours after onset of symptoms. This image combines results of lactate and N-acetyl-aspartate (NAA) spectroscopy. The bright white area (curved arrow) represents a region that has high levels of lactate and no NAA, which indicate the absence of viable neurons. The gray area (straight arrows) contains both lactate and NAA, indicating the presence of anaerobic metabolism and viable neurons. This image may represent an ischemic penumbra (gray area) surrounding a region of infarcted neurons (white area).

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