Tmax is a sensitive indicator of myocardial ischaemia under adenosine stress as determined by static PET imaging: a study in a porcine model

Aim To evaluate T max , defined as the time of residual function R( t ) reaching its maximum, as an indicator of myocardial ischaemia and compare its efficacy with other computed tomography perfusion (CTP) parameters. Materials and methods Eight Bama miniature pigs with 50–90% left anterior descending artery stenosis underwent adenosine stress myocardial CTP and 13 N NH 3 position-emission tomography (PET) perfusion imaging. T max , myocardial blood flow (MBF), myocardial blood volume (MBV), mean transit time (MTT), and time to peak (TTP) were calculated from CTP images. PET images were evaluated as ischaemia or non-ischaemia. Using PET as a reference standard, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were calculated. Multiple comparisons of the receiver operating characteristic (ROC) curves between T max and other parameters were performed. The diagnostic performance of the combination of each two parameters was calculated and compared with T max. Results T max was significantly higher in ischaemic segments compared with non-ischaemic segments. Multiple comparisons of the ROCs indicated that T max was better than MBF or TTP but not statistically different from MBV. T max was superior to the combination of (MBF + MBV) but not to (MBF + TTP) or (MBV + TTP). Conclusion T max in dynamic stress CTP provides good diagnostic accuracy for detecting myocardial ischaemia, especially in sensitivity and NPV, compared with PET method. T max has better performance than MBF or TTP or combination of (MBF + MBV) in diagnosing myocardial ischaemia.