Blood Oxygen Level-Dependent MR Imaging of Lower Extremities in Peripheral Artery Disease and Its Correlation With Walking Performance

Abstract

Background: A noninvasive and reliable approach to quantitatively measure muscle perfusion of lower extremity is needed to aid the diagnosis and treatment of peripheral artery disease (PAD).

Purpose: To verify the reproductivity of using blood oxygen level-dependent (BOLD) imaging to evaluate perfusion in lower extremities, and explore its correlation with walking performance in patients with PAD.

Study type: Prospective observational study.

Subjects: Seventeen patients with lower extremity PAD (mean age: 67 ± 6 years, 15 males) and eight older adults (controls).

Field strength/sequence: Dynamic multi-echo gradient echo T2* weighted imaging at 3T.

Assessment: Perfusion was analyzed in regions of interest according to muscle groups. Perfusion parameters were measured, such as minimum ischemia value (MIV), time to peak (TTP), and gradient during reactive hyperemia (Grad) by two independent users. Walking performance experiments including short physical performance battery (SPPB) and 6-minute walk were tested in patients.

Statistical tests: BOLD parameters were compared using Mann-Whitney U test and Kruskal-Wallis test. Relations between parameters and walking performance were assessed by Mann-Whitney U test and Spearman's correlation coefficient.

Results: Good to perfect agreement was demonstrated for all perfusion parameters of interuser reproducibility, and the interscan reproducibility of MIV, TTP, and Grad was good. The TTP of the patients was longer than that of the controls (87.85 ± 38.85 s vs. 36.54 ± 7.27 s), while the Grad of patients was smaller (0.16 ± 0.12 msec/s vs. 0.24 ± 0.11 msec/s). Among PAD patients, the MIV was significantly lower in the low SPPB subgroup (score 6-8) than in the high SPPB group (score 9-12), and the TTP was negatively correlated with 6-minute walk distance (ρ = -0.549).

Data conclusion: BOLD imaging method had overall good reproducibility for the perfusion assessment of calf muscles. The perfusion parameters were different between PAD patients and controls, and were correlated with lower extremity function.

Evidence level: 2 TECHNICAL EFFICACY: Stage 2.

Keywords: blood oxygen level-dependent; magnetic resonance imaging; perfusion assessment; peripheral artery disease; walking performance.