Diffusion-weighted Imaging of Patients with Subacute Cerebral Ischemia: Comparison with Conventional and Contrast-enhanced MR Imaging
Michael Augustina,
Roland Bammer
,a,
Josef Simbrunnera,
Rudolf Stollbergera,
Hans-Peter Hartunga and
Franz Fazekas,a
a From the Department of Neurology (M.A., R.B., R.S., H-P.H., F.F.) and the MR Institute (M.A., R.B., J.S., R.S., F.F.), Karl-Franzens University, Graz, Austria.
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FIG 1. Graph compares the probability of lesion detection for the subgroup of 41 patients with evidence of subacute ischemic damage on any of the MR sequences used, including contrast-enhanced T1-weighted images. The first and second columns indicate the percentage of patients with a subacute lesion on T2-weighted sequences without and with knowledge of the patients' symptoms. The third column shows the relative sensitivity of DWI without clinical information
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FIG 2. 80-year-old patient with left hemiparesis and ataxia.
A–C, DWI (TR/TEdiff/TE = approximately 1500/115/18; 2 RR intervals) study (A) clearly shows multiple recent small ischemic lesions in the right centrum semiovale. These lesions are less visible on FLAIR image (6000/130/2, TI = 1900) (B) and T2-weighted-FSE image (2900/120/1) (C) and could not be identified as areas of subacute infarction on these sequences.
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FIG 3. 63-year-old patient with right hemiparesis.
A–L, Three days after stroke, DWI studies (approximately 1500/115/18; 2 RR intervals) (A–C) show two more clinically unexpected ischemic lesions in the cerebellum (A, B), suggestive of embolism. These two lesions would not have been definitively labeled as subacute on FLAIR (D–F) (6000/130/2, TI = 1900) or T2-weighted (2500/90/1) (G–I) sequences, especially in the presence of negative findings on contrast-enhanced images (556/14/2) (J–L).
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FIG 4. A–D, Multiple tiny cortico-subcortical lesions in the right motor region on DWI (approximately 1500/115/18; 2 RR intervals) study (A) confirm the ischemic origin of mild hemiparesis 4 days after stroke. These changes might have gone undetected on T2-weighted FSE (2900/120/1) (B), FLAIR (6000/130/2, TI = 1900) (C), or contrast-enhanced (588/14/2) (D) images
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FIG 5. Graph compares the percentage of patients with subacute ischemic lesions on DWI and contrast-enhanced T1-weighted sequences in the subgroup of 28 patients in whom contrast-enhanced studies were obtained
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FIG 6. 63-year-old patient with preexisting ischemic lesions.
A–D, Mild hemiparesis is well seen on FSE (2900/120/1) (A) and FLAIR (6000/130/2, TI = 1900) (B) sequences. DWI (approximately 1500/115/18; 2 RR intervals) sequence (C) depicts the area of recent ischemic damage 7 days after stroke. Contrast-enhanced MR image (588/14/2) (D) remains negative.
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