Incidence of New Diffusion-Weighted Imaging Lesions Outside the Area of Initial Hypoperfusion Within 1 Week After Acute Ischemic Stroke
Background and Purpose—New diffusion-weighted imaging (DWI) lesions are common in patients with acute ischemic stroke. The pathophysiology of these new lesions is unclear. We differentiated new DWI lesions outside the area of initial hypoperfusion from those confined to the area of initial hypoperfusion.
Methods—Patients with acute stroke underwent 3 MRI examinations: on admission, on the next day, and 4 to 7 days after symptom onset. Patients were included if a perfusion deficit was present on the initial scan. Lesions on DWI images were delineated manually. Coregistered DWI images were analyzed visually for new hyperintensities. In reference to the perfusion maps (mean transit time), patients were classified as having “outside lesions” if new DWI lesions were outside or both outside and inside the area of the initial perfusion deficit or “inside lesions” if new DWI lesions were completely inside.
Results—We enrolled 164 patients. Thirty-eight patients (23%) had outside lesions and 34 patients (21%) had inside lesions. In multivariable regression analysis, new outside lesions were significantly associated with symptomatic carotid stenosis, multiple index lesions pattern, and high low-density lipoprotein levels. New inside lesions were significantly associated with (spontaneous or thrombolytic) vessel recanalization, multiple index lesions pattern, and low low-density lipoprotein levels.
Conclusion—Outside and inside lesions represent different pathophysiological entities. More specifically patients with outside lesions may have an increased risk for subsequent cerebrovascular events.
- diffusion-weighted imaging
- magnetic resonance imaging
- new DWI lesion
- perfusion imaging
- silent stroke
- Received March 1, 2012.
- Revision received May 2, 2012.
- Accepted June 15, 2012.
- © 2012 American Heart Association, Inc.