Mr perfusion studies with <i>t</i>₁‐weighted echo planar imaging

TLDR

The T1 perfusion model has proven effective in brain functional studies, yet partial‑volume effects of CSF/gray matter and differing blood versus white‑matter T1 values can compromise flow‑contrast accuracy. The study develops a new steady‑state brain blood‑flow imaging method using selective and nonselective inversion pulses. Flow‑sensitive images are obtained with selective inversion and flow‑insensitive images with nonselective inversion; subtraction and T1 fitting yield flow maps, while the authors propose strategies to mitigate partial‑volume and T1‑difference problems. The subtraction produced flow‑weighted images with clear gray‑white contrast in cortical gray matter, thalamus, and basal ganglia, and T1 fitting of the paired images yielded preliminary brain blood‑flow maps.

Abstract

Abstract The T 1 perfusion model has worked well in brain functional studies where flow changes are measured. Using selective and nonselective inversion pulses, a new method has been developed to study steady‐state brain blood flow. The authors obtained flow‐sensitive images using selective inversion and flow‐insensitive images using nonselective inversion. Subtraction of flow‐insensitive images from flow‐sensitive images gave us flow‐weighted images with good gray‐white flow contrast in cortical gray matter as well as in the thalamus and basal ganglia. Fitting T 1 S of flow‐insensitive and flow‐sensitive images allowed us to obtain preliminary results of brain blood flow maps. Two specific problems can seriously affect the accuracy of the brain blood flow values and the gray‐white flow contrast of brain blood flow maps. These are the problems of the partial volume effect of CSF and gray matter, and the difference between blood T 1 and white matter T 1 . The authors discuss in detail the character of these problems and present a number of approaches to manage such problems.