Combined (1)H MR spectroscopy and diffusion-weighted MRI improves the prediction of stroke outcome

The prognostic value of the biochemical changes seen with proton MR spectroscopy (1H MRS) in ischemic stroke was examined. Acute diffusion-weighted imaging (DWI) was used to identify regions of ischemia for 1H MRS voxel localization.

Nineteen patients had 36 1H MRS studies, 13 patients acutely (mean, 11.1 hours), 10 subacutely (mean, 3.9 days), and 13 at outcome (mean, 82 days). Single-voxel, long-echo, timepoint-resolved spectroscopy was used to obtain lactate, n-acetylaspartate (NAA), choline, and creatine levels from the infarct core. Outcome measures were final infarct volume and clinical assessment scales (Canadian Neurological Scale, Barthel Index, and Rankin Scale).

Acute lactate/choline ratio correlated more strongly with clinical outcome scores (r = 0.76 to 0.83; p < 0.01) and final infarct size (r = 0. 96; p < 0.01) than acute DWI lesion volume or acute NAA/choline ratio. Combination of acute lactate/choline ratio with acute DWI lesion volume improved prediction of all outcome scores (R2 = 0.80 to 0.90). The predictive effect of acute lactate/choline ratio was independent of acute DWI lesion volume (p < 0.001). In subacute and chronic infarction, both lactate/choline and NAA/choline ratios continued to correlate with outcome (p < 0.05). At the chronic stage, persistent lactate/choline ratio elevation strongly correlated with outcome measures (r = 0.71 to 0.87).

Lactate/choline ratio measured in the acute infarct core by 1H MRS improves the prediction of stroke outcome and provides prognostic information complementary to DWI. Lactate/choline ratio could be used as an additional marker to select patients for acute and chronic therapies.