Abstract
BackgroundDark rim artifacts in first-pass cardiovascular magnetic resonance (CMR) perfusion images can mimic perfusion defects and affect diagnostic accuracy for coronary artery disease (CAD). We evaluated whether quantitative myocardial blood flow (MBF) can differentiate dark rim artifacts from true perfusion defects in CMR perfusion.MethodsRegadenoson perfusion CMR was performed at 1.5 T in 76 patients. Significant CAD was defined by quantitative invasive coronary angiography (QCA) ≥ 50% diameter stenosis. Non-significant CAD (NonCAD) was defined as stenosis by QCA < 50% diameter stenosis or computed tomographic coronary angiography (CTA) < 30% in all major epicardial arteries. Dark rim artifacts had study specific and guideline-based definitions for comparison purposes. MBF was quantified at the pixel-level and sector-level.ResultsIn a NonCAD subgroup with dark rim artifacts, stress MBF was lower in the subendocardial than midmyocardial and epicardial layers (2.17 ± 0.61 vs. 3.06 ± 0.75 vs. 3.24 ± 0.80 mL/min/g, both p < 0.001) and was also 30% lower than in remote regions (2.17 ± 0.61 vs. 2.83 ± 0.67 mL/min/g, p < 0.001). However, subendocardial stress MBF in dark rim artifacts was 37–56% higher than in true perfusion defects (2.17 ± 0.61 vs. 0.95 ± 0.43 mL/min/g, p < 0.001). Absolute stress MBF differentiated CAD from NonCAD with an accuracy ranging from 86 to 89% (all p < 0.001) using pixel-level analyses. Similar results were seen at a sector level.ConclusionQuantitative stress MBF is lower in dark rim artifacts than remote myocardium but significantly higher than in true perfusion defects. If confirmed in larger series, this approach may aid the interpretation of clinical stress perfusion exams.Trial registrationClinicalTrials.gov Identifier: NCT00027170; first posted 11/28/2001; updated 11/27/2017.
Highlights
Dark rim artifacts in first-pass cardiovascular magnetic resonance (CMR) perfusion images can mimic perfusion defects and affect diagnostic accuracy for coronary artery disease (CAD)
Definitions of dark rim artifacts Since this paper aimed to examine the characteristics of dark rim artifacts and whether they might explain some false positive perfusion defects, we defined a dark rim artifact as hypointense subendocardial regions on stress perfusion images in the Patients without coronary artery disease (NonCAD) group
We studied the diagnostic performance of dark rim artifact definitions as described in the Society for Cardiovascular Magnetic Resonance (SCMR) Guidelines [9] which have three definitions of dark rim artifact: 1) An apparent perfusion defect seen in stress that lasts < 7 beats is considered a “dark rim artifact” while one that lasts ≥ 7 beats is called a “true positive perfusion defect,” 2) An apparent perfusion defect seen at rest and at stress is a “dark rim artifact” while one at stress only is a “true positive defect,” and 3) if myocardial signal intensity decreases below baseline prior to myocardial enhancement, the apparent defect is a dark rim artifact
Summary
Dark rim artifacts in first-pass cardiovascular magnetic resonance (CMR) perfusion images can mimic perfusion defects and affect diagnostic accuracy for coronary artery disease (CAD). We evaluated whether quantitative myocardial blood flow (MBF) can differentiate dark rim artifacts from true perfusion defects in CMR perfusion. Stress cardiovascular magnetic resonance (CMR) perfusion can detect CAD and quantification improves the objectivity of interpretation [2]. A dark rim artifact that mimics a true defect is one important limitation in CMR perfusion. There are numerous causes of dark rim artifact including: Gibbs ringing [3], inadequate spatial resolution [4, 5], motion artifacts [6], non-uniformity across k-space [7], and partial volume errors. Different artifacts from multiple causes can combine to exacerbate dark rim artifact
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