Detection of doxorubicin cardiotoxicity by using iodine-123 BMIPP early dynamic SPECT: quantitative evaluation of early abnormality of fatty acid metabolism with the Rutland method.

BACKGROUND: To evaluate the possibility of predicting the development of doxorubicin-induced cardiomyopathy, we performed quantitative assessment of the early kinetics of iodine-123 beta-methyl-iodophenyl-pentadecanoic acid (I-123 BMIPP) by means of dynamic myocardial SPECT.
METHODS: Thirty-six patients with various malignancies were examined. I-123 BMIPP dynamic myocardial SPECT was performed before chemotherapy, after chemotherapy, or both. Immediately after the injection of I-123 BMIPP (111 MBq), 30-second dynamic SPECT data were acquired successively for 15 minutes. The left ventricular (LV) myocardium was divided into 8 segments in short-axial and vertical slices. By using the time-activity curve (TAC) of each myocardial segment [Mo(t)] as an output function and the TAC of the LV cavity [B(t)] as an input function, the Rutland equation, Mo(t)/B(t)= F + K Integral of(B(t)dt/B(t)), was used as a means of assessing all segments.
RESULTS: Mo(t)/B(t) showed a good linear correlation with Integral of(B(t)dt/B(t)) from 30 seconds to 4 minutes in all 456 segments. The mean K value of 8 LV segments was significantly lower after chemotherapy than before chemotherapy (0.071+/-0.019 [n = 21] vs. 0.095+/-0.025 [n = 36], P<.001). In 21 patients in whom dynamic SPECT was performed both before and after chemotherapy, the mean K values of left ventricle showed a significant decrease, from 0.101+/-0.024 to 0.071 +/-0.019 (P<.0001). The fractional change in the value of K after chemotherapy showed a significant linear correlation with the administered dose of doxorubicin (r = 0.648, P<.002).
CONCLUSION: I-123 BMIPP dynamic myocardial SPECT may be clinically useful, because it permits the early detection of doxorubicin-induced cardiomyopathy.