The Feasibility of a Model-Based Iterative Reconstruction Technique Tuned for the Myocardium on Myocardial Computed Tomography Late Enhancement.

Objectives: This study evaluated the feasibility of a model-based iterative reconstruction technique (MBIR) tuned for the myocardium on myocardial computed tomography late enhancement (CT-LE).
Methods: Twenty-eight patients who underwent myocardial CT-LE and late gadolinium enhancement (LGE) magnetic resonance imaging (MRI) within 1 year were retrospectively enrolled. Myocardial CT-LE was performed using a 320-row CT with low tube voltage (80 kVp). Myocardial CT-LE images were scanned 7 min after CT angiography (CTA) without additional contrast medium. All myocardial CT-LE images were reconstructed with hybrid iterative reconstruction (HIR), conventional MBIR (MBIR_cardiac), and new MBIR tuned for the myocardium (MBIR_myo). Qualitative (5-grade scale) scores and quantitative parameters (signal-to-noise ratio [SNR] and contrast-to-noise ratio [CNR]) were assessed as image quality. The sensitivity, specificity, and accuracy of myocardial CT-LE were evaluated at the segment level using an American Heart Association (AHA) 16-segment model, with LGE-MRI as a reference standard. These results were compared among the different CT image reconstructions.
Results: In 28 patients with 448 segments, 160 segments were diagnosed with positive by LGE-MRI. In the qualitative assessment of myocardial CT-LE, the mean image quality scores were 2.9 ± 1.2 for HIR, 3.0 ± 1.1 for MBIR&#95;cardiac, and 4.0 ± 1.0 for MBIR&#95;myo. MBIR&#95;myo showed a significantly higher score than HIR (P < 0.001) and MBIR&#95;cardiac (P = 0.018). In the quantitative image quality assessment of myocardial CT-LE, the median image SNR was 10.3 (9.1-11.1) for HIR, 10.8 (9.8-12.1) for MBIR&#95;cardiac, and 16.8 (15.7-18.4) for MBIR&#95;myo. The median image CNR was 3.7 (3.0-4.6) for HIR, 3.8 (3.2-5.1) for MBIR&#95;cardiac, and 6.4 (5.0-7.7) for MBIR&#95;myo. MBIR&#95;myo significantly improved the SNR and CNR of CT-LE compared to HIR and MBIR&#95;cardiac (P < 0.001). The sensitivity, specificity, and accuracy for the detection of myocardial CT-LE were 70%, 92%, and 84% for HIR; 71%, 92%, and 85% for MBIR&#95;cardiac; and 84%, 92%, and 89% for MBIR&#95;myo, respectively. MBIR&#95;myo showed significantly higher image quality, sensitivity, and accuracy than the others (P < 0.05).
Conclusions: MBIR tuned for myocardium improved image quality and diagnostic performance for myocardial CT-LE assessment.
Competing Interests: Conflict of interest: Shota Nakano is an employee of Canon Medical Systems Corporation. The rest of the authors declare no conflict of interest.
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