All MR exams were performed on a 3 T MRI scanner (Discovery 750, GE Healthcare, Milwaukee Wisconsin) using an 8-channel brain array coil. Conventional MRI protocol included post-contrast 3D T1-weighted fast spoiled gradient-echo (FSPGR) imaging (TE/TR = 3.0/6.9 ms; FA = 9°; FOV = 25 cm; matrix = 256 × 256; slices = 180, slice thickness = 1 mm, interslice gap 1 mm). Contrast enhanced exams were performed using either gadobenate dimeglumine (Bracco Diagnostics) or gadobutrol (Bayer AG), both at 0.1 mmol/kg.
ASL was performed using pseudocontinuous labeling with a 3D stack-of-spirals fast spin echo readout; this reflects the GE product ASL sequence. PCASL-specific parameters included a labeling duration of 1,450 ms and post labeling delay of 2025 ms with 3D spiral readout parameters as follows: spiral interleaves = 8; points per spiral = 512; slices = 36; slice thickness 4.0–4.2 mm; FOV = 24–26 cm; in-plane resolution = 3.64–4.53 mm2; bandwidth = 62.5 kHz; TE = 9.5–10.5 ms; TR = 4,800–4,847 ms; NEX = 3; and scan time = 4 min 32 s–4 min 42 s.
ASL was performed using pseudocontinuous labeling with a 3D stack-of-spirals fast spin echo readout; this reflects the GE product ASL sequence. PCASL-specific parameters included a labeling duration of 1,450 ms and post labeling delay of 2025 ms with 3D spiral readout parameters as follows: spiral interleaves = 8; points per spiral = 512; slices = 36; slice thickness 4.0–4.2 mm; FOV = 24–26 cm; in-plane resolution = 3.64–4.53 mm2; bandwidth = 62.5 kHz; TE = 9.5–10.5 ms; TR = 4,800–4,847 ms; NEX = 3; and scan time = 4 min 32 s–4 min 42 s.
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