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Updated: May 21, 2026
In Vivo Quantitative Assessment of Myocardial Structure, Function, Perfusion and Viability Using Cardiac Micro-computed Tomography
Published on: February 16, 2016
In vivo chronic myocardial infarction characterization by spin locked cardiovascular magnetic resonance
Walter R T Witschey1, Gerald A Zsido, Kevin Koomalsingh
1Department of Surgery, University of Pennsylvania, Philadelphia, PA, USA. witschey@mail.med.upenn.edu
Insights
T1ρ-weighted cardiovascular magnetic resonance (CMR) accurately measures infarct size without contrast agents, offering a safe alternative for patients with renal failure. This technique shows promise for visualizing myocardial infarction (MI) and characterizing cardiac tissue.
Area of Science:
- Cardiovascular Magnetic Resonance Imaging
- Medical Physics
- Biomedical Engineering
Background:
- Late gadolinium-enhanced (LGE) cardiovascular magnetic resonance (CMR) is standard for myocardial viability assessment but contraindicated in renal failure due to nephrogenic systemic fibrosis risk.
- T1- and T2-weighted CMR are insensitive to chronic myocardial infarction (MI) without contrast agents.
- Contrast-agent-free techniques are needed for infarct characterization, especially in patients with contraindications to gadolinium.
Purpose of the Study:
- To explore T1ρ-weighted rotating frame CMR techniques for infarct characterization without contrast agents.
- To hypothesize that T1ρ CMR accurately measures infarct size in chronic MI.
- To evaluate the potential of T1ρ CMR as a contrast-agent-free method for visualizing myocardial infarction.
Main Methods:
- Seven Yorkshire swine with induced myocardial infarction underwent high-resolution CMR at 8 weeks post-infarction.
- Both Late Gadolinium Enhanced (LGE) and T1ρ CMR imaging were performed on a 3T scanner.
- Infarct size was quantified using T1ρ CMR, LGE CMR, and optical planimetry post-excision for comparison.
Main Results:
- T1ρ CMR demonstrated a contrast-to-noise ratio (CNR) of 2.7 ± 0.1, comparable to LGE CMR's 2.8 ± 0.1.
- 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%).
- T1ρ relaxation times differed significantly between infarct (91.7 ms) and remote myocardium (47.2 ms).
Conclusions:
- T1ρ-weighted imaging effectively discriminates between infarct scar and healthy myocardium.
- T1ρ CMR is a promising contrast-agent-free technique for visualizing myocardial infarction.
- This method may aid in distinguishing edema and scar tissue, and in tissue characterization for myocarditis and fibrosis.
Background:
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.
Methods:
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.
Results:
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 < 0.05).T1ρ relaxation times were T1ρinfarct = 91.7 ms in the infarct and T1ρremote = 47.2 ms in the remote myocardium.
Conclusions:
T1ρ-weighted imaging using long spin locking pulses enables high discrimination between infarct and myocardium. T1ρ CMR may be useful to visualizing MI without the need for exogenous contrast agents for a wide range of clinical cardiac applications such as to distinguish edema and scar tissue and tissue characterization of myocarditis and ventricular fibrosis.
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