perfusion-imaging.jpgQUANTITATIVE STROKE IMAGING

 

Stroke diagnosis, prognosis, and treatment can be greatly aided by quantitative analysis of diffusion and perfusion imaging. Quantitative blood flow measures are capable of discerning virtually imperceptible differences between salvageable and unsalvageable tissues in ischemic stroke.

The Buffalo Neuroimaging Analysis Center (BNAC) has been involved in the development and refinement of rapid and reliable methods to create quantitative stroke images, including cerebral blood flow maps, cerebral blood volume maps, and mean transit time maps.
 
The use of perfusion and diffusion imaging in acute ischemic stroke, via the “mismatch model,” has provided the potential to more accurately understand the consequences of thrombolytic therapy on an individual patient basis. However, few semi-automated methods exist to assist in quantification of the extent of mismatch presence (ischemic penumbra), and none have demonstrated a robust ability to predict infarcted tissue outcome. Recently, BNAC applied a Hidden Markov Random Field (HMRF) approach for the rapid and reliable identification and quantification of perfusion diffusion mismatch. We showed that the described method represents a significant improvement over thresholding techniques and should be further explored as a means for accurate identification of tissue at risk in acute ischemic stroke.
 

PERFUSION IMAGING AS DIFFERENTIAL DIAGNOSTIC TOOL

Recently, BNAC investigated differences in lesions and surrounding normal appearing white matter (NAWM) by perfusion-weighted imaging (PWI) and diffusion-weighted imaging (DWI) in patients with acute and chronic ischemic stroke and multiple sclerosis (MS). This study found prolonged mean transit time (MTT) values in lesions and surrounding normal appearing white matter (NAWM) of patients with acute and chronic ischemic stroke when compared to patients with MS. PWI is a promising tool for differential diagnosis between acute ischemic and acute demyelinating lesions. The results of this study contribute to a better understanding of the extent of hemodynamic abnormalities in lesions and surround NAWM in patients with MS.