In vivo chronic myocardial infarction characterization by spin locked cardiovascular magnetic resonance

• Published in: Journal of cardiovascular magnetic resonance 2012-06, Vol.14 (1), p.37-37, Article 48
• Main Authors: Witschey, Walter R T, Zsido, Gerald A, Koomalsingh, Kevin, Kondo, Norihiro, Minakawa, Masahito, Shuto, Takashi, McGarvey, Jeremy R, Levack, Melissa M, Contijoch, Francisco, Pilla, James J, Gorman, 3rd, Joseph H, Gorman, Robert C
• Format: Article
• Language: English
• Subjects: Animals; Chronic Disease; Contrast agents; Contrast media; Contrast Media - administration & dosage; Coronary vessels; Diagnosis; Disease Models, Animal; Experiments; Follow-Up Studies; Heart attack; Heart Ventricles - pathology; Heart Ventricles - physiopathology; Imaging; Injections, Intravenous; Locks; Magnetic fields; Magnetic resonance; Magnetic resonance imaging; Magnetic Resonance Imaging, Cine - adverse effects; Magnetic Resonance Imaging, Cine - methods; Meglumine - administration & dosage; Methods; Myocardial Contraction - physiology; Myocardial infarction; Myocardial Infarction - pathology; Myocardial Infarction - physiopathology; Myocardium; Myocardium - pathology; Relaxation time; Reproducibility of Results; Scars; Swine; Veins & arteries
• ISSN: 1097-6647; 1532-429X; 1532-429X
• DOI: 10.1186/1532-429X-14-37

Late gadolinium enhanced (LGE) cardiovascular magnetic resonance (CMR) is frequently used to evaluate myocardial viability, estimate total infarct size and transmurality, but is not always straightforward is and contraindicated in patients with renal failure because of the risk of nephrogenic systemic fibrosis. T2- and T1-weighted CMR alone is however relatively insensitive to chronic myocardial infarction (MI) in the absence of a contrast agent. The objective of this manuscript is to explore T1ρ-weighted rotating frame CMR techniques for infarct characterization without contrast agents. We hypothesize that T1ρ CMR accurately measures infarct size in chronic MI on account of a large change in T1ρ relaxation time between scar and myocardium. 7Yorkshire swine underwent CMR at 8 weeks post-surgical induction of apical or posterolateral myocardial infarction. Late gadolinium enhanced and T1ρ CMR were performed at high resolution to visualize MI. T1ρ-weighted imaging was performed with a B₁  = 500 Hz spin lock pulse on a 3 T clinical MR scanner. Following sacrifice, the heart was excised and infarct size was calculated by optical planimetry. Infarct size was calculated for all three methods (LGE, T1ρ and planimetry) and statistical analysis was performed. T1ρ relaxation time maps were computed from multiple T1ρ-weighted images at varying spin lock duration. Mean infarct contrast-to-noise ratio (CNR) in LGE and T1ρ CMR was 2.8 ± 0.1 and 2.7 ± 0.1. The variation in signal intensity of tissues was found to be, in order of decreasing signal intensity, LV blood, fat and edema, infarct and healthy myocardium. Infarct size measured by T1ρ CMR (21.1% ± 1.4%) was not significantly different from LGE CMR (22.2% ± 1.5%) or planimetry (21.1% ± 2.7%; p