⁸²Rb PET/CT: entering a new area of myocardial perfusion imaging?

Excerpt

In this issue of the European Journal of Nuclear Medicine and Molecular Imaging, Flotats et al. [1] report a striking improvement in image quality of myocardial perfusion studies with the use of ⁸²Rb PET/CT as compared to conventional ^99mTc-labelled SPECT/CT. When using PET/CT in concert with the positron-emitting myocardial perfusion tracer ⁸²Rb, the improvement in image quality also manifested in a higher interpretative confidence and interreader agreement of ⁸²Rb perfusion images than observed for ^99mTc-labelled SPECT/CT. In particular, the current study is unique in that ⁸²Rb PET/CT and ^99mTc-labelled SPECT/CT were performed in the same patient with known or suspected coronary artery disease (CAD). Previous investigations commonly compared the sensitivity and specificity of cardiac PET versus SPECT perfusion imaging in the detection of flow-limiting epicardial lesions [2]. For example, Go et al. [3] showed sensitivity, specificity and accuracy of 95, 82 and 92 % for ⁸²Rb PET and 79, 76 and 78 % for ²⁰¹Tl SPECT for haemodynamically obstructive CAD lesions. Further, Stewart et al. [4] reported that overall sensitivity, specificity and accuracy of ⁸²Rb PET for detection of coronary artery lesions ≥50 % diameter stenosis were 84, 88 and 85 %, respectively. In comparison to this, the performance of ²⁰¹Tl SPECT revealed a sensitivity of 84 % but a low specificity of 53 % and a diagnostic accuracy of 79 %. The commonly higher sensitivity in the identification of flow-limiting epicardial lesions with ⁸²Rb PET as compared with SPECT imaging, either with ²⁰¹Tl or ^99mTc-labelled perfusion tracers, can be related to the higher spatial and contrast resolution of ⁸²Rb PET, while the photon attenuation–free images of PET imaging may account for the relative increase in specificity [2]. …