Leukoaraiosis, Ischemic Stroke, and Normal White Matter on Diffusion-Weighted MRI

Helenius, Johanna MD
Soinne, Lauri MD
Salonen, Oili MD, PhD
Kaste, Markku MD, PhD
Tatlisumak, Turgut MD

From the Departments of Neurology (J.H., L.S., M.K., T.T.) and Radiology (O.S.), Helsinki University Central Hospital, Helsinki, Finland.

Received August 10, 2001;

final revision received September 20, 2001; accepted October 10, 2001.

Correspondence to Dr Johanna Helenius, Department of Neurology, Helsinki University Central Hospital, Haartmaninkatu 4, 00290 Helsinki, Finland. E-mail [email protected]

Stroke 33(1):p 45-50, January 2002.

Background and Purpose—

Leukoaraiosis is a radiological finding of uncertain pathogenesis with bilateral patchy or diffuse areas of hyperintensity of the cerebral white matter (WM) on T2-weighted MRI. Using diffusion-weighted MRI (DWI), we aimed to test (1) whether the average apparent diffusion coefficient (ADC_av) values of the regions of leukoaraiosis vary according to the degree of the severity of leukoaraiosis and whether the regions of leukoaraiosis could be distinguished (2) from normal WM or (3) from ischemic strokes of various ages.

Methods—

We compared 85 patients with leukoaraiosis, 22 healthy subjects with no leukoaraiosis on the conventional MR images, and 10 patients with ischemic strokes serially imaged <6 hours, 24 hours, 1 week, 1 month, and 3 months after stroke onset. All subjects were studied with DWI in 3 orthogonal directions with 2 b values (b=0 and b=1000 s/mm²) at 1.5 T. ADC_av values were determined for the regions of leukoaraiosis, ischemic lesions, and normal WM.

Results—

The more severe the leukoaraiosis was, the higher the ADC_av values of the leukoaraiotic regions became. The ADC_av values (in 10⁻³ mm²/s) of the regions of leukoaraiosis (0.92 to 1.27) were significantly higher than that of the normal WM (0.69±0.04) and that of the ischemic strokes at 6 hours (0.38±0.07), 24 hours (0.36±0.10), and 1 week (0.51±0.09). One-month-old ischemic strokes (1.08±0.33) had ADC_av values similar to those of leukoaraiotic regions, whereas 3-month-old infarcts (1.59±0.32) showed significantly higher ADC_av values than the leukoaraiotic regions.

Conclusions—

The regions of leukoaraiosis show characteristic changes in ADC_av values, and DWI can be used to differentiate acute and chronic ischemic stroke lesions from leukoaraiosis.