Affiliation:
1. Department of Neurology Vanderbilt University Medical Center Nashville Tennessee USA
2. Mallinckrodt Institute of Radiology Washington University School of Medicine St. Louis Missouri USA
3. Department of Radiology and Radiological Sciences Vanderbilt University Medical Center Nashville Tennessee USA
4. Department of Pediatrics Vanderbilt University Medical Center Nashville Tennessee USA
5. Department of Psychiatry and Behavioral Sciences Vanderbilt University Medical Center Nashville Tennessee USA
Abstract
PurposeAsymmetric spin echo (ASE) MRI is a method for measuring regional oxygen extraction fraction (OEF); however, extravascular tissue models have been shown to under‐estimate OEF. The hypothesis investigated here is that the addition of a vascular‐space‐occupancy (VASO) pre‐pulse will more fully suppress blood water signal and provide global OEF values more consistent with physiological expectation and 15O positron emission tomography (PET)‐validated T2‐relaxation‐under‐spin‐tagging (TRUST) OEF measures.MethodsHealthy adults (n = 14; age = 27.7 ± 5.2 y; sex = 7/7 male/female) were scanned at 3.0T. Multi‐echo ASE without inter‐readout refocusing (ASERF−), multi‐echo ASE with inter‐readout refocusing (ASERF+), and single‐echo VASO‐ASE were acquired twice each with common spatial resolution = 3.44 × 3.44 × 3.0 mm and τ = 0–20 ms (interval = 0.5 ms). TRUST was acquired twice sequentially for independent global OEF assessment (τCPMG = 10 ms; effective TEs = 0, 40, 80, and 160 ms; spatial resolution = 3.4 × 3.4 × 5 mm). OEF intraclass‐correlation‐coefficients (ICC), summary statistics, and group‐wise differences were assessed (Wilcoxon rank‐sum; significance: two‐sided p < 0.05).ResultsASERF+ (OEF = 36.8 ± 1.9%) and VASO‐ASE (OEF = 34.4 ± 2.3%) produced OEF values similar to TRUST (OEF = 36.5 ± 4.6%, human calibration model; OEF = 32.7 ± 4.9%, bovine calibration model); however, ASERF− yielded lower OEF (OEF = 26.1 ± 1.0%; p < 0.01) relative to TRUST. VASO‐ASE (ICC = 0.61) yielded lower ICC compared to other ASE variants (ICC >0.89).ConclusionVASO‐ASE and TRUST provide similar OEF values; however, VASO‐ASE spatial coverage and repeatability improvements are required.
Funder
National Institute of Neurological Disorders and Stroke
Subject
Radiology, Nuclear Medicine and imaging