Cardiac Computed Tomography Coronary Angiography Post Non-diagnostic or Equivocal Myocardial Perfusion SPECT

Myocardial perfusion imaging with single-photon emission computed tomography (SPECT) is an important imaging modality in the management of patients with cardiovascular disease. Myocardial perfusion SPECT (MP-SPECT) plays a key role in the establishing diagnosis, prognosis, assessment of therapy and intervention, and myocardial viability [1-3]. The accuracy of the interpreting and reporting MP-SPECT studies, either by visual interpretation or with assistance of computer software packages is dependent on the overall quality of the study and how consistent and predictable is the tracer distribution for patient's specifi c disease state. MP-SPECT is a complex process, artifacts and pitfalls can arise at any stage in MP-SPECT process, and can be grouped into issues related to the instrument, issues related to the patients, attenuation artifacts, tracer kinetics/distribution artifacts, and processing related artifacts [4]. The interpreting physicians should develop understanding of all possible MPS artifacts and pitfalls, and develop a systematic approach to correct them and how to incorporate their infl uence into the fi nal interpretation of the study. The American Society of Nuclear Cardiology (ASNC) is strongly in favor of the standardization of MP-SPECT reporting [5]. The fi nal impression is the most critical part of the MP-SPECT report. The fi nal report must states clearly, whether the study is normal or abnormal. However, in some cases with interpretive uncertainty, multi category reporting of MPS has been proposed, 5-category system include: normal, probably normal, equivocal, probably abnormal, and abnormal [6]. The use of multi category in the fi nal impression results in incorporating non-perfusion and clinical information, and therefore enhances risk stratifi cation of MPS compared with a dichotomous normal/abnormal approach. Non diagnostic study such as inadequate stress or poor quality images is another