Author's reply

Abstract

Drs Celik and Karacalioglu raised interesting points concerning our study published in a recent issue of the Journal, which showed that lung uptake of radiotracers was a single best parameter in the identification of left main trunk (LMT) disease among 508 patients with suspected or known coronary artery disease (CAD) [[1]Shiba C. Chikamori T. Hida S. Igarashi Y. Tanaka H. Hirose K. Ohtaki Y. Usui Y. Miyagi M. Hatano T. Yamashina A. Important parameters in the detection of left main trunk disease using stress myocardial perfusion imaging.J Cardiol. 2009; 53: 43-52Abstract Full Text Full Text PDF PubMed Scopus (16) Google Scholar]. The questions they raised concerned a potential effect of concomitant pulmonary disease on lung uptake of radiotracers and reliability of a 20-segement scoring system on myocardial SPECT imaging. In patients with chronic pulmonary disease, diffuse lung uptake of radiotracer is often observed on SPECT image both after stress and at rest [[2]Pham R. Bellezuoli E. Diffuse pulmonary uptake of Tc-99m sestamibi due to chemical pneumonitis.J Nucl Cardiol. 2006; 13: 127-129Crossref PubMed Scopus (5) Google Scholar]. In contrast, lung uptake of radiotracer in patients with extensive and severe CAD such as LMT disease is observed only after exercise or pharmacologic stress [1Shiba C. Chikamori T. Hida S. Igarashi Y. Tanaka H. Hirose K. Ohtaki Y. Usui Y. Miyagi M. Hatano T. Yamashina A. Important parameters in the detection of left main trunk disease using stress myocardial perfusion imaging.J Cardiol. 2009; 53: 43-52Abstract Full Text Full Text PDF PubMed Scopus (16) Google Scholar, 3Choy J.B. Leslie W.D. Clinical correlates of Tc-99m sestamibi lung uptake.J Nucl Cardiol. 2001; 8: 639-644Crossref PubMed Scopus (24) Google Scholar]. Lung uptake of radiotracer disappears on the delayed SPECT image. The definition of lung uptake has been clearly stated in our study [[1]Shiba C. Chikamori T. Hida S. Igarashi Y. Tanaka H. Hirose K. Ohtaki Y. Usui Y. Miyagi M. Hatano T. Yamashina A. Important parameters in the detection of left main trunk disease using stress myocardial perfusion imaging.J Cardiol. 2009; 53: 43-52Abstract Full Text Full Text PDF PubMed Scopus (16) Google Scholar]. In addition, patients with severe valvular heart disease were excluded from the study. Thus, potential confounding effects due to pulmonary or valvular disease seem negligible. In the evaluation of myocardial SPECT image including a 20-segment scoring system, two cardiologists with vast experience of this methodology contributed. In addition, our institution has been involved in the J-ACCESS study, in which inter-institutional reproducibility of SPECT imaging has been affirmed [[4]Nakajima K. Kusuoka H. Nishimura S. Yamashina A. Nishimura T. Normal limit of ejection fraction and volumes determined by gated SPECT in clinically normal patients without cardiac events: a study based on the J-ACCESS database.Eur J Nucl Mol Imaging. 2007; 34: 1088-1096Crossref PubMed Scopus (55) Google Scholar]. Nevertheless, we concur with Drs Celik and Karacalioglu in that before applying our study in clinical practice, a learning curve should be taken into consideration to avoid pitfalls of this technique.