ABSTRACT Purpose To achieve high resolution (≤ 1 mm isotropic) whole‐brain perfusion imaging at 7 T with next generation ASL pulse sequence, reconstruction algorithm, and MRI hardware. Methods We capitalized on three major innovations: (1) FLASH‐based pseudo‐Continuous ASL (pCASL) sequence with rotated golden‐angle stack‐of‐spirals (rGA‐SoS) sampling; (2) dynamic compressed sensing (CS) reconstruction with high spatiotemporal resolution and motion‐resolved self‐navigation; and (3) high density array coil and high‐performance Impulse gradient of the NexGen 7 T scanner. Whole‐brain laminar perfusion imaging was validated by correlation with histological data of microvascular and cell body density, as well as through finger‐tapping (FT) and working memory (WM) fMRI tasks. Results The proposed rGA‐SoS sequence achieved a 3.3‐fold SNR and 2‐fold higher intraclass correlation coefficient (ICC) compared to matched Cartesian sampling at 7 T, enabling up to 0.8 mm isotropic spatial resolution and/or a temporal resolution of 14 s at 1 mm isotropic. Resting‐state perfusion showed strong correlations with microvascular and cell body density. Laminar perfusion fMRI revealed a two‐peak activation in the primary motor cortex induced by FT, and distinct laminar profiles for task‐positive and task‐negative networks during WM task. Conclusion This method offers a noninvasive imaging tool to bridge the gap between mesoscopic MRI with microscopic cellular imaging, as well as to investigate neural excitation and inhibition underlying positive and negative fMRI activations.
Zhao et al. (Thu,) studied this question.