Differences in fatty acid metabolic disorder between ischemic myocardium and doxorubicin-induced myocardial damage: assessment using BMIPP dynamic SPECT with analysis by the Rutland method.
Dynamic myocardial SPECT data acquired with 15-(123)I-(p-iodophenyl)-3-(R,S)-methylpentadecanoic acid (BMIPP) were analyzed by the Rutland method. The relative time-activity curves generated from dynamic SPECT in normal control subjects were compared with similar curves from patients with established ischemic heart disease (IHD) and doxorubicin-induced myocardial damage (DxMD). Comparison of such time-activity curves may provide some indirect information concerning qualitative differences in BMIPP metabolism.


METHODS
Thirteen patients with various malignancies who received doxorubicin, 16 patients with IHD, and 15 normal control subjects were examined. Immediately after the bolus injection of BMIPP, dynamic data acquisition with a 3-head SPECT system was started and continued for 15 min. Using the time-activity curves of the myocardium as the output function (Mo(t)) and the time-activity curves of the left ventricular cavity as the input function (B(t)), the Rutland equation was calculated: Mo(t)/B(t) = F + K integral B(t)dt/B(t), where F is the blood - background subtraction factor and K is the uptake constant. The duration of the linear portion in this equation and the K values were evaluated.


RESULTS
Mo(t)/B(t) was plotted against integral B(t)dt/B(t). Mo(t)/B(t) showed a good linear correlation with integral B(t)dt/B(t) from 30 s to 230 +/- 57 s in normal control subjects. The duration of this linearity was prolonged to 317 +/- 79 s in DxMD (P = 0.0014) and shortened to 182 +/- 58 s in IHD (P = 0.039). The mean K value was 0.0740 +/- 0.0184 in normal control subjects, significantly higher than the K values of 0.0599 +/- 0.0148 in DxMD patients (P = 0.026) and 0.0497 +/- 0.0189 (P = 0.0020) in IHD patients.


CONCLUSIONS
Analysis of BMIPP dynamic SPECT data by the Rutland method is useful for detecting qualitative differences in BMIPP metabolism in various types of myocardial damage. It is speculated that the fatty acid metabolic disorder is characterized by a delay in metabolism in DxMD and by increased backdiffusion in IHD.
D000368:Aged; D000970:Antineoplastic Agents / Q000009:adverse effects*; D009202:Cardiomyopathies / Q000139:chemically induced* / Q000000981:diagnostic imaging / Q000378:metabolism; D004317:Doxorubicin / Q000009:adverse effects*; D005227:Fatty Acids / Q000378:metabolism* / Q000493:pharmacokinetics; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging; D006801:Humans; D007457:Iodine Radioisotopes; D007462:Iodobenzenes / Q000493:pharmacokinetics; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods
D000970:Antineoplastic Agents; D005227:Fatty Acids; D007457:Iodine Radioisotopes; D007462:Iodobenzenes; C049338:iodofiltic acid; D004317:Doxorubicin