Fig. 2
From: Time-of-flight and black-blood MRI to study intracranial arteries in rats
MRI bed and TOF and BB sequences for rat brain vasculature imaging. a, b Rat positioning in prone position in the MRI bed; intracranial arteries were imaged using a 3-T nanoScan® MRI unit equipped with a rat head coil. c Gradient-echo TOF with three-dimensional encoding mode, mainly used for unenhanced TOF angiography. Before the excitation, a slab selective saturation pulse was applied (90° RF) with selection gradient in z direction (Gz) and spoiler gradients. The saturation band was placed above the imaging volume. After the saturation, a gradient echo encoding and readout came with an excitation RF pulse, phase encodings, and readout. A “RAMP” excitation pulse was used where the flip angle increases linearly along the direction of flow. Additionally, flow compensation was applied as well to eliminate artifacts caused by blood flow. The compensation gradients were placed after the RF pulse and reset the moment of all applied gradients. d Two-dimensional BB fast spin-echo with double inversion: the first inversion pulse was nonselective, impacting the whole volume, the second one, slice selective; the echo train of spin echo filled the k space; spin-echo RF pulses were slice selective. BB Black-blood, Gx Gradient in x direction, Gy Gradient in y direction, MRI Magnetic resonance imaging, RAMP Ramped, RF Radiofrequency, TOF Time-of-flight