Blood Oxygenation Level-Dependent CMR-Derived Measures in Critical Limb Ischemia and Changes With Revascularization

• Published in: Journal of the American College of Cardiology Vol. 67; no. 4; pp. 420 - 431
• Main Authors: Bajwa, Adnan, Wesolowski, Roman, Patel, Ashish, Saha, Prakash, Ludwinski, Francesca, Ikram, Mohammed, Albayati, Mostafa, Smith, Alberto, Nagel, Eike, Modarai, Bijan
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 02.02.2016; Elsevier Limited; Elsevier Biomedical
• Subjects: Adult; Age; Aged; Aged, 80 and over; angioplasty; Angioplasty - methods; Biopsy; Cardiology; Cardiovascular; cardiovascular magnetic resonance; Disease Progression; Female; Follow-Up Studies; Humans; Ischemia; Ischemia - blood; Ischemia - diagnosis; Ischemia - therapy; Leg - blood supply; Magnetic Resonance Imaging - methods; Male; Medical imaging; Methods; Middle Aged; Mortality; Muscle, Skeletal - metabolism; Muscle, Skeletal - pathology; Original Investigation; Oxygen - blood; Patients; perfusion; Prognosis; Reproducibility of Results; Severity of Illness Index; Studies; surgery; Ultrasonic imaging; Ultrasonography, Doppler, Duplex; Young Adult; CLI; perfusion; ABPI; DCE; CMR; SRi; cardiovascular magnetic resonance; C:F; Grad; PAD; ASL; BOLD; GRE; angioplasty; surgery; capillary-fiber ratio; blood oxygenation level-dependent; arterial spin labeling; gradient recalled echo; critical limb ischemia; dynamic contrast enhanced; ankle-brachial pressure index; peripheral arterial disease; signal reduction during ischemia; gradient during reactive hyperemia
• ISSN: 0735-1097; 1558-3597; 1558-3597
• DOI: 10.1016/j.jacc.2015.10.085

Use of blood oxygenation level-dependent cardiovascular magnetic resonance (BOLD-CMR) to assess perfusion in the lower limb has been hampered by poor reproducibility and a failure to reliably detect post-revascularization improvements in patients with critical limb ischemia (CLI). This study sought to develop BOLD-CMR as an objective, reliable clinical tool for measuring calf muscle perfusion in patients with CLI. The calf was imaged at 3-T in young healthy control subjects (n = 12), age-matched control subjects (n = 10), and patients with CLI (n = 34). Signal intensity time curves were generated for each muscle group and curve parameters, including signal reduction during ischemia (SRi) and gradient during reactive hyperemia (Grad). BOLD-CMR was used to assess changes in perfusion following revascularization in 12 CLI patients. Muscle biopsies (n = 28), obtained at the level of BOLD-CMR measurement and from healthy proximal muscle of patients undergoing lower limb amputation (n = 3), were analyzed for capillary-fiber ratio. There was good interuser and interscan reproducibility for Grad and SRi (all p < 0.0001). The ischemic limb had lower Grad and SRi compared with the contralateral asymptomatic limb, age-matched control subjects, and young control subjects (p < 0.001 for all comparisons). Successful revascularization resulted in improvement in Grad (p < 0.0001) and SRi (p < 0.0005). There was a significant correlation between capillary-fiber ratio (p < 0.01) in muscle biopsies from amputated limbs and Grad measured pre-operatively at the corresponding level. BOLD-CMR showed promise as a reliable tool for assessing perfusion in the lower limb musculature and merits further investigation in a clinical trial.