Diffusion-weighted Imaging of Cerebral Ischemic Infarcts: Comparison with T2-weighted Imaging in Signal Intensity

ABSTRACT

PURPOSE: To investigate whether ischemic infarct can be staged by evaluating signal intensities on diffusionweighted (DWI) and turbo spin echo T2-weighted images(T2WI). MATERIALS AND METHODS: DWI and T2WI of 27 patientswith ischemic infarct were retrospectively evaluated. Infarcts were divided into five stages depending on time ofonset hyperacute within 12 hours, acute between 12 hours and 3 days, subacute between 3 and 10 days, earlychronic between 10 and 30 days, and late chronic after 30 days. Signal intensities of these lesions compared withnormal brain on DWI and T2WI were visually evaluated and divided into six patterns. Pattern 1 included high signalon DWI and iso-signal on T2WI, pattern 2 showed high signal on both DWI and T2WI with higher contrast on DWI,pattern 3 showed the same high signal on both images; pattern 4 revealed high signal on both images with highercontrast on T2WI, pattern 5 showed iso-signal on DWI and high signal on T2WI, and pattern 6 revealed low signal onDWI and high signal on T2WI. These five clinical stages and six MRI patterns were correlated in each patient. RESULTS: Six cases were hyperacute, six were acute, eight were subacute, three were early chronic, and four werelate chronic. At the hyperacute stage, five cases showed pattern 1 (83%) and one case, pattern 2. At the acutestage, all six cases showed pattern 2. At the subacute subcute stage, seven cases showed pattern 2(87.5%) and onecase pattern 4. At the early chronic stage, two cases showed pattern 2(66.7%) and one case, pattern 5. At the latechronic stage, all cases showed pattern 6. CONCLUSION: DWI is useful for the detection of early ischemic infarct,and stages of ischemic infarcts can be estimated by evaluating signal intensities on DWI and T2WI.