1) Understand the clinical relevance of myocardial perfusion in terms of diagnosis and prognosis. 2) Compare the differences between test characteristics of the applied imaging modalities. 3) Identify and tailor the pre-test probability of the patient population to the imaging modality. 4) Interpret the diagnostic validity of the test outcome per imaging modality.
Contrary to coronary angiography , FFR or CCTA, myocardial perfusion imaging (MPI) is the only method to demonstrate myocardial ischemia. It reflects the final result of the effects of coronary flow impairment due to stenosis or obstruction together with compensatory flow through communicating coronary vessels and flow through collaterals. Therefore it is the ultimate proof for haemodynamically relevant coronary flow impairment. While different modalities for MPI have different diagnostic accuracy, the overall accuracy to diagnose hemodynamically significant coronary artery disease (CAD) is good .Analysis of MPI results in clinical setting is mostly performed by visual evaluation of presence and pattern of hypoenhancement of the myocardium during first pass of intravenously injected contrast or tracer. This method relies on the existence of regions with normal perfusion as reference, which limits its accuracy in cases of multi-vessel disease or balanced ischemia. Quantitative methods capable of solving this limitation were first established in PET, where time-resolved acquisition of the first-pass of tracer uptake and direct quantification of tracer concentration from PET attenuation were developed. With these characteristics, tracer kinetic modeling can be applied to produce independent quantitative estimates of perfusion in stress and rest, known as absolute perfusion measures or biomarkers. The added clinical value of PET over relative and visual perfusion analysis has been demonstrated. With recent technological advances in MRI and CT imaging, these techniques are receiving increased attention for evaluation of myocardial perfusion biomarkers. State-of-the-art MRI and CT have better spatial and temporal resolution compared to PET. MRI and CT also have wider possibilities for integration into current clinical workup for CAD due to their wider availability and increasing clinical role in comprehensive diagnosis of CAD.
Oudkerk, M,
Myocardial Perfusion in Clinical Care. Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL.
http://archive.rsna.org/2014/14000963.html
