Right ventricular abnormalities assessed by myocardial single-photon emission computed tomography using technetium-99m sestamibi/tetrofosmin in right ventricle-originated ventricular tachyarrhythmias
Mariko Eguchi, MDa,
Kazufumi Tsuchihashi, MD, PhDa,
Tomoaki Nakata, MD, PhDa,
Akiyoshi Hashimoto, MD, PhDa and
Kazuaki Shimamoto, MD, PhDa
a Second Department of Internal Medicine, Sapporo Medical University School of Medicine, Sapporo, Japan
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Figure 1 Selection of two short-axis tomograms and one horizontal long-axis tomogram for RV assessment and schematic presentation of six RV segments (Seg). Segments 1, 2, 3 and 4 are derived from the basal and apical one-third slices, in which the whole LV circumference is visualized. The RV horizontal long axis (segments 5 and 6) is selected at the mid-ventricular transverse level by reference to LV slices. Right ventricular uptake was visually scored as follows: 3+ = no definite abnormality; 2+ = slight reduced uptake; 1+ = markedly reduced uptake; 0 = defect.
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Figure 2 Right ventricular tomograms derived from a patient with idiopathic RVT (upper panel) and a control subject (lower panel) show neither definite abnormality nor RV dilation.
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Figure 3 Three typical RV abnormalities observed in the outflow (top), inflow (middle) and multiple regions (bottom) in patients with ARVC.
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Figure 4 Comparison of total RV scores among the three groups and the correlation with RVEF. If the cut-off value of the total RV score of  11 is used for differentiating patients with organic RVT from those with idiopathic RVT or normal subjects, the sensitivity, specificity and diagnostic accuracy were 79% (19 of 24 patients), 100% (48 of 48) and 93% (67 of 72), respectively. The organic RVT group had a significantly lower total RV score as compared with the control and idiopathic RVT groups (left panel). The total RV score had a close positive correlation with RVEF derived from radionuclide ventriculography: RVEF (%) = 1.4x total RV score + 23.7 (r = 0.702, p < 0.001) (right panel).
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Figure 5 A, There was a close correlation between the RV/LV count ratio and RV visual score. Note that there were significant differences in the RV/LV count ratio among RV scores. There were significant differences in the RV/LV count ratio (B) and in RV score (C) between segments with and those without RV asynergy. The overall sensitivity and specificity of scintigraphic determination by using the lower scores 0 and 1 for detecting RV asynergy were 76.1% (35 of 46 segments) and 76.6% (49 of 64), respectively (C). The solid circles, open circles and open squares indicate organic RVT, idiopathic RVT and control subjects, respectively.
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