Fig. 1: Schematic diagram of mvPI calculation process.
From: Assessing cerebral microvascular volumetric with high-resolution 4D cerebral blood volume MRI at 7 T
a, Cardiac phase definition: two complete cardiac cycles of pulse signals are shown. The time from one cycle’s systolic peak to the next systolic peak is divided into 10 equal phases, defined as phases 1–10. b, Retrospective sorting of images into 10 cardiac phases. The time and signal intensity curves of VASO (red) and BOLD (blue) signals are shown. The lower figure shows the trigger time corresponding to each image and its corresponding cardiac phase (black). c, CBF and CBV0 laminar profiles based on high-resolution (iso-1.25 mm) ASL scans and CBV0 were derived based on the listed equation. d, Variations of VASO signals across cardiac phases after retrospective sorting of VASO images; the mvPI was calculated based on the listed equations (details in Methods). Eq, equation; min, minutes; s, seconds.
