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Updated: Feb 13, 2026
Cardiac Magnetic Resonance for the Evaluation of Suspected Cardiac Thrombus: Conventional and Emerging Techniques
Published on: June 11, 2019
Diagnosis of Microvascular Angina Using Cardiac Magnetic Resonance
Alexander Liu1, Rohan S Wijesurendra1, Joanna M Liu1
1Oxford Centre for Clinical Magnetic Resonance Research, Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom.
Insights
Cardiac magnetic resonance (CMR) can diagnose microvascular angina in patients with nonobstructive coronary artery disease (NOCAD). This noninvasive method accurately identifies impaired myocardial perfusion reserve index (MPRI) linked to coronary microvascular dysfunction (CMD).
Area of Science:
- Cardiology
- Medical Imaging
- Diagnostic Techniques
Background:
- Diagnosing coronary microvascular dysfunction (CMD) in angina patients with nonobstructive coronary artery disease (NOCAD) is challenging.
- Cardiac magnetic resonance (CMR) offers high-resolution myocardial perfusion assessment, valuable for obstructive coronary artery disease (CAD).
Purpose of the Study:
- To validate CMR for diagnosing microvascular angina in NOCAD patients.
- To compare CMR findings with invasive index of microcirculatory resistance (IMR) and obstructive CAD data.
Main Methods:
- Adenosine stress CMR was performed on 50 angina patients and 20 controls to assess left ventricular function, ischemia (MPRI, MBF), and infarction.
- Invasive coronary angiography with fractional flow reserve (FFR) and IMR measurements were conducted within 7 days.
Main Results:
- In NOCAD patients, impaired MPRI (≥25 U) correlated with CMD, similar to obstructive CAD.
- CMR-derived MPRI accurately detected impaired perfusion (AUC: 0.90, sensitivity: 89%, specificity: 95%).
- Impaired stress MBF augmentation, not resting MBF, characterized CMD in NOCAD patients.
Conclusions:
- CMR can objectively and noninvasively assess microvascular angina in patients with NOCAD.
- A combined CMR-based diagnostic pathway for epicardial and microvascular CAD requires further validation.
Background:
In patients with angina and nonobstructive coronary artery disease (NOCAD), confirming symptoms due to coronary microvascular dysfunction (CMD) remains challenging. Cardiac magnetic resonance (CMR) assesses myocardial perfusion with high spatial resolution and is widely used for diagnosing obstructive coronary artery disease (CAD).
Objectives:
The goal of this study was to validate CMR for diagnosing microvascular angina in patients with NOCAD, compared with patients with obstructive CAD and correlated to the index of microcirculatory resistance (IMR) during invasive coronary angiography.
Methods:
Fifty patients with angina (65 ± 9 years of age) and 20 age-matched healthy control subjects underwent adenosine stress CMR (1.5- and 3-T) to assess left ventricular function, inducible ischemia (myocardial perfusion reserve index [MPRI]; myocardial blood flow [MBF]), and infarction (late gadolinium enhancement). During subsequent angiography within 7 days, 28 patients had obstructive CAD (fractional flow reserve [FFR] ≤0.8) and 22 patients had NOCAD (FFR >0.8) who underwent 3-vessel IMR measurements.
Results:
In patients with NOCAD, myocardium with IMR <25 U had normal MPRI (1.9 ± 0.4 vs. controls 2.0 ± 0.3; p = 0.49); myocardium with IMR ≥25 U had significantly impaired MPRI, similar to ischemic myocardium downstream of obstructive CAD (1.2 ± 0.3 vs. 1.2 ± 0.4; p = 0.61). An MPRI of 1.4 accurately detected impaired perfusion related to CMD (IMR ≥25 U; FFR >0.8) (area under the curve: 0.90; specificity: 95%; sensitivity: 89%; p < 0.001). Impaired MPRI in patients with NOCAD was driven by impaired augmentation of MBF during stress, with normal resting MBF. Myocardium with FFR >0.8 and normal IMR (<25 U) still had blunted stress MBF, suggesting mild CMD, which was distinguishable from control subjects by using a stress MBF threshold of 2.3 ml/min/g with 100% positive predictive value.
Conclusions:
In angina patients with NOCAD, CMR can objectively and noninvasively assess microvascular angina. A CMR-based combined diagnostic pathway for both epicardial and microvascular CAD deserves further clinical validation.
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