Diagnostic performance of hybrid cardiac SPECT/CT imaging for patients with takotsubo cardiomyopathy

BACKGROUND: The diagnostic performance of SPECT-only imaging for takotsubo cardiomyopathy (TC) is limited due to the lack of coronary artery distribution information. The aim of this study was to evaluate the diagnostic performance of hybrid cardiac SPECT/CT for patients with TC or acute coronary syndrome (ACS). METHODS: Twenty-two patients with apical ballooning left ventricular (LV) dysfunction who underwent cardiac perfusion SPECT using (99m)Tc-methoxy-isobutyl-isonitrile (MIBI), cardiac fatty-acid metabolism SPECT using (123)I–beta-methyl-P-iodophenyl-pentadecanoic acid (BMIPP), cardiac CT, and hybrid cardiac SPECT/CT imaging were analyzed. On the SPECT images, MIBI and BMIPP defects were quantified using a 17-segment model with a 5-point grading system and a summed MIBI defect score (SMDS), summed BMIPP defect score (SBDS), and summed mismatch score (SMS) were calculated. Furthermore, apical and non-apical MDS, BDS, and mismatch scores (A- and NA-MDS, A- and NA-BDS, and A- and NA-MS) were calculated. These quantitative scores were compared between the TC (n = 11) and ACS (n = 11) groups, and the diagnostic performances of SPECT-only imaging and hybrid SPECT/CT imaging were compared. For all patients, the diagnoses of both SPECT-only and SPECT/CT imaging were categorized as TC: SPECT accumulation defects around apical LV wall deviated from the actual coronary artery territories, equivocal: unclear relationship of accumulation defects and the coronary artery territories, or non-TC: accumulation defects coincided with the coronary artery territories. RESULTS: SMDS and SBDS did not significantly differ between TC and ACS patients [SMDS: 5 (3–7) vs. 8 (4–16), p = 0.216; SBDS: 10 (8–12) vs. 18 (9–24), p = 0.354]. While A-MDS and A-BDS did not significantly differ between patients with TC and ACS (p = 0.567 and p = 0.386, respectively), NA-MDS and NA-BDS were significantly lower for patients with TC (p = 0.022 and p = 0.022, respectively). Compared with SPECT-only imaging (sensitivity: 30% and specificity: 81%), hybrid SPECT/CT imaging showed a higher accuracy (sensitivity: 90% and specificity: 100%) for the diagnosis of TC. CONCLUSIONS: Hybrid cardiac SPECT/CT imaging may have superior diagnostic performance compared with SPECT-only imaging for patients with TC.