Reproducibility of myocardial perfusion reserve – variations in measurements from post processing using commercially available software


Purpose: Adenosine stress first pass cardiac magnetic resonance imaging (CMRI) is a rapidly evolving tool in the diagnosis of ischemic heart disease (IHD). The rest and stress first pass myocardial perfusion data may be interpreted using commercially available software for calculation of time intensity curves in order to generate a numeric value of the segmental or whole heart myocardial perfusion reserve index (MPRI). The objective of this study was to determine the inter- and intra-observer reliability of the data generated by standard commercially available software.
Methods: Data from 20 adenosine stress CMRI (1.5 T) studies were analyzed using commercially available CAAS MRV 3.3 software (Pie Medical Imaging B.V., Netherlands) for calculation of the MPRI.
The stress CMRI was performed using a standardized protocol in 20 women including 10 women with angina and the absence of obstructive CAD and 10 healthy volunteers. MPRI calculation was made in a standardized manner on separate occasions by two independent observers. A single observer repeated the calculation of MPRI three months later, without reference to the prior data. Basal, mid, and apical segments, for the whole myocardium, sub-endocardium, and sub-epicardium were analyzed. Intra-class correlation coefficients (ICC), repeatability coefficients (RC), and coefficients of variation (CoV) were determined.
Results: The MPRI results by repeated software measurements were highly correlated, with potentially important variations in measurement observed. The myocardial inter-observer ICC was 0.80 (95% CI, 0.57, 0.92) with a CoV of 7.5%, and intra-observer ICC was 0.89 (95% CI, 0.77, 0.95) with a CoV of 3.6%. The mid-ventricular level MPRI was most reproducible, with intra-observer ICC at 0.91 (95% CI, 0.77, 0.97); intra-observer measurement was more reproducible than inter-observer measurement.
Conclusions: There is variation in measurement of MPRI observed in post processing of perfusion data when using a standardized approach and commercially available software. This has implications in the interpretation of data obtained for clinical and research purposes.

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