1349862 - A comparison between three post-processing quantitative perfusion methods

Several analysis methods for Quantitative Perfusion (QP) CMR have been proposed, some vendor-specific, others generic. Published literature shows differences in the Myocardial Blood Flow (MBF) measurements between these methods.  Current limitations include the lack of consensus on optimal acquisition and analysis techniques, which ideally, should yield MBF and myocardial perfusion reserve (MPR) estimates consistent with, and interchangeable across studies and with PET, which remains the reference-standard. Lack of inter-vendor standardisation remains an important hinderance for the implementation of QP CMR into routine clinical practice.

Methods:

We investigated the differences in global stress MBF, global rest MBF and myocardial perfusion reserve (MPR) between three post-processing quantitative perfusion methods using two field strengths.

27 patients referred for stress myocardial perfusion CMR were recruited. Basic demographic data and CMR data were collected. Two scanners (1.5T Ingenia and 3T Achieva-TX (Philips, Best, The Netherlands), were used.  Both sequences used dual acquisition quantitative perfusion acquisition included in the Philips CMR Research Software and comparable contrast-agent dosing regimens.

Data from both field strengths were grouped and then analysed using 3 different QP methods (A, B and C) to derive global rest MBF, global stress MBF and MPR. MBF and MPR measurements were gathered using pre-defined segmental ROI contours which were averaged to derive a global value. The data were tested for normality and then methods were compared with one another using repeated measures one way ANOVA for parametric data, or Friedman’s test for non-parametric data, as appropriate.

Results:

All patients completed studies with good quality. 20 scans were performed on 1.5T and 7 scans were performed on 3T.  Mean ejection fraction was 55 ±11%, mean age was 65 ±10 years with a male: female distribution (22:5). Mean global MBF and MPR values are represented in table 1 with the relevant comparative test results.  There was no statistically significant difference in MPR using the three methods (F(2,52) =2.39, p=0.102) or in rest MBF (X²(2) = 0.92, p= 0.63).  Statistically significant differences in stress MBF (F (2,52) =7.36, p=0.002) were seen. Bland Altman plots are represented for comparison between QP methods A and B, A and C, and B and C in figure 2.

Conclusion:

Analysis of QP at two field strengths and between three analysis methods did not demonstrate agreement between QP methods for MBF.  However, MPR may be a better metric to use. Since myocardial blood flow values may be expected to differ between methods due to different modelling, it may be that each QP method requires their own reference standards if they are to be used for clinical decision making in the future.  Further studies are required between more QP techniques, incorporating multiple vendor QP implementations to determine clinical utility of QP and for international standardisation.