RSNA 2004 

Abstract Archives of the RSNA, 2004


SST12-09

Effects of Lesion Size and Tissue Type on the Time Course of the Core Apparent Diffusion Coefficient in Ischemic Stroke

Scientific Papers

Presented on December 3, 2004
Presented as part of SST12: Neuroradiology/Head and Neck (Acute Stroke)

Participants

William A, Copen MD, Presenter: Nothing to Disclose
Lee H. Schwamm MD, Abstract Co-Author: Nothing to Disclose
Gilberto Gonzalez MD, PhD, Abstract Co-Author: Nothing to Disclose
Ona Wu PhD, Abstract Co-Author: Nothing to Disclose
Carla Branco Harmath MD, Abstract Co-Author: Nothing to Disclose
Pamela Whitney Schaefer MD, Abstract Co-Author: Nothing to Disclose
Walter J. Koroshetz MD, Abstract Co-Author: Nothing to Disclose
A. Gregory Sorensen MD, Abstract Co-Author: Nothing to Disclose
et al, Abstract Co-Author: Nothing to Disclose

PURPOSE

Diffusion-weighted MRI (DWI) not only provides sensitive detection of acute ischemic stroke, but also can assess the stage of tissue damage by measuring the apparent diffusion coefficient (ADC) of water in affected brain tissue. Previous reports have shown that ADC changes, and therefore tissue damage, may proceed at different rates in patients of different ages or in infarcts of different etiologies. We sought to determine whether lesion size and tissue type also affect the rate of change of ADC.

METHOD AND MATERIALS

119 stroke patients underwent DWI at 189 timepoints. ADC was measured in the core of each infarct, and divided by ADC in normal-appearing tissue in the contralateral hemisphere to yield relative ADC (rADC). Lesions were classified as small (appearing in 5 or fewer slices) or large (6 or more slices). Measurements were made either in gray matter (GM) or white matter (WM). A statistical model was used to describe the initial fall and subsequent rise of rADC over time as a function of lesion size and tissue type.

RESULTS

Transition from decreasing to increasing rADC occurred earlier in large than in small lesions (p=.015). There was no significant main effect of tissue type with respect to the time of transition. However, there was a significant interaction of lesion size and tissue type (p=0.045), such that, among large lesions only, transition occurred earlier in GM than in WM lesions (p=.045). There were significant main effects of both lesion size and tissue type on the subsequent rate of chronic ascent of rADC, which was more rapid in small lesions than in large lesions (p=<.001), and more rapid in GM than WM (p=.009). However, there was a significant interaction of size and tissue type with respect to rate of ascent (p<.001), with reversal of the above-mentioned size- and tissue type-related effects, such that the predicted rate of ascent was greater for large WM lesions than for any other subgroup.

CONCLUSIONS

In infarcts with relatively slow rates of ADC progression, tissue degradation also may proceed at a slower rate, suggesting a longer potential window of efficacy for thrombolytic or neuroprotective therapy in these patients.

DISCLOSURE

Cite This Abstract

Copen, W, Schwamm, L, Gonzalez, G, Wu, O, Harmath, C, Schaefer, P, Koroshetz, W, Sorensen, A, et al, , Effects of Lesion Size and Tissue Type on the Time Course of the Core Apparent Diffusion Coefficient in Ischemic Stroke.  Radiological Society of North America 2004 Scientific Assembly and Annual Meeting, November 28 - December 3, 2004 ,Chicago IL. http://archive.rsna.org/2004/4417233.html