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AJNR - American Journal of Neuroradiology

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Evolution of Water Diffusion and Anisotropy in Hyperacute Stroke: Significant Correlation between Fractional Anisotropy and T2

Yelda Ozsunar^d,*, P. Ellen Grant^a,c,*, Thierry A. G. M. Huisman^a,c, Pamela W. Schaefer^a, Ona Wu^a,c, A. Gregory Sorensen^a,c, Walter J. Koroshetz^b and R. Gilberto Gonzalez^a,c

^a Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston
^b Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston
^c MGH-NMR Center, Charlestown, MA
^d Department of Radiology, School of Medicine, Adnan Menderes University, Aydin, Turkey

View larger version (80K): [in a new window]   FIG 1. Tracing method for the VOIs. The infarct was outlined on isotropic DWI, section by section, by using a free-hand method. On each section, the ROI was flipped about the vertical axis and placed in the same location on contralateral normal side to obtain a mirror-image ROI. All section ROIs were combined to provide one stoke and one contralateral normal VOI for each patient. All VOIs were projected onto inherently coregistered echo-planar T2WIs, FA maps, and ADC maps. Top left, Isotropic DWI. Top right, Echo-planar T2WI. Bottom left, FA map. Bottom right, ADC map.

View larger version (10K): [in a new window]   FIG 2. Graph demonstrates a highly significant inverse linear correlation between FA and T2 signal intensity (r = –0.691, P = .00009). Note that all patients with a relative increase in T2 signal intensity of < 0.10 also have increased relative FA values.

View larger version (54K): [in a new window]   FIG 3. Images in a 59-year-old man who underwent an MR examination 8 hours after the onset of symptoms. An acute infarction in the right middle cerebral artery distribution was observed; this was due to thromboembolism. The FA map demonstrates increased signal intensity, whereas the echo-planar T2WI shows no hyperintensity. This is an example of how increased FA was associated with minimal T2 change. Far left, Isotropic DWI. Middle left, ADC map. Middle right, FA map. Far right, echo-planar T2WI.

View larger version (54K): [in a new window]   FIG 4. Images in a 71-year-old woman who presented with slurred speech and left-sided weakness and who was imaged 11 hours after the onset of these symptoms. DWI demonstrates an acute infarction involving the right MCA territory. Decreased FA (far left) and increased T2 signal intensity (far right) was observed in the right corona radiata. This is an example of how decreased FA was associated with increased T2 signal intensity. Far left, Isotropic DWI. Middle left, ADC map. Middle right, FA map Far right, Echo-planar T2WI.