ABC | Volume 113, Nº6, December 2019

Original Article Ket et al. Myocardial ischemia by SPECT and CCTA Arq Bras Cardiol. 2019; 113(6):1092-1101 Figure 3 – Comparison between myocardial perfusion methods sensitivity and specificity for detecting obstructive coronary artery disease. SPECT: Single-photon emission computed tomography; CT: computed tomography. 0.93 0.66 0.5 0.75 SPECT CT perfusion 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 Sensitivity Specificity specificity of 66%, considering that scintigraphy is the standard method used to assess perfusion. Tanami et al . 32 clearly state that CCTA has better accuracy than SPECT for detecting significant obstructive CAD. Hence, it is necessary to explore this finding and understand that many patients with false- negative SPECT results are unnecessarily submitted to cardiac catheterization, due to lack of anatomical assessment. 32-35 An interesting finding, in line with previous studies, is the comparison between the sensitivity and specificity of the two perfusion techniques in detecting obstructive coronary lesions, considering that coronary CT is the gold standard for the diagnosis of anatomic CAD. 35-37 In this study, we observed better ischemic catheterization by CT myocardial perfusion when compared with SPECT. It is important to highlight that catheterization was not used as the gold standard and, thus, these results may vary if other methods of reference are used, such as flow fractional reserve (FFR). 37-39 Rochitte et al., 35 showed that combined CCTA and stress perfusion imaging accurately identifies patients with > 50% lesion in the catheterization and who presented perfusion defects at SPECT. Moreover, the rational use of these techniques and multimodality assessment are important in modern cardiology, since they are always associated with increased exposure to radiation. 36 In the study carried out by Arbab-Zadeh et al., 36 greater accuracy was observed for CT perfusion imaging when compared with SPECT (92% versus 62%, p < 0.001), but the Figure 4 – Analysis of the area under the ROC curve showing diagnostic perfusion performance of CT [0.84 (CI 95%: 0.67-0.94, p < 0.001)] and of scintigraphy (SPECT) [0.58 (CI 95%: 0.40-0.74, p < 0.001)], in this study. 100 100 80 80 60 60 40 40 20 20 0 0 Sensitivity 100 - Specificity SPECT perfusion CT perfusion >50% stenosis on CCTA 1097