Abstract
The goals of this investigation were to assess the accuracy of 18F-fluorodihydrorotenone (18F-FDHR) as a new deposited myocardial flow tracer and to compare the results to those for 201Tl. Methods: The kinetics of these flow tracers in 22 isolated, erythrocyte- and albumin-perfused rabbit hearts were evaluated over a flow range encountered in patients. The 2 flow tracers plus a vascular reference tracer (131I-albumin) were introduced as a bolus through a port just above the aortic cannula. Myocardial extraction, retention, washout, and uptake parameters were computed from the venous outflow curves with the multiple-indicator dilution technique and spectral analysis. Results: The mean ± SD initial extraction fractions for 18F-FDHR (0.85 ± 0.07) and 201Tl (0.87 ± 0.05) were not significantly different, although the initial extraction fraction for 18F-FDHR declined with flow (P < 0.0001), whereas the initial extraction fraction for 201Tl did not. The washout of 201Tl was faster (P < 0.001) and more affected by flow (P < 0.05) than was the washout of 18F-FDHR. Except for the initial extraction fraction, 18F-FDHR retention was higher (P < 0.001) and less affected by flow (P < 0.05) than was 201Tl retention. Reflecting its superior retention, the net uptake of 18F-FDHR was better correlated with flow than was that of 201Tl at both 1 and 15 min after tracer introduction (P < 0.0001 for both comparisons). Conclusion: The superior correlation of 18F-FDHR uptake with flow indicates that it is a better flow tracer than 201Tl in the isolated rabbit heart. Compared with the other currently available positron-emitting flow tracers (82Rb, 13N-ammonia, and 15O-water), 18F-FDHR has the potential of providing excellent image resolution without the need for an on-site cyclotron.
Footnotes
Received Mar. 19, 2004; revision accepted Jul. 15, 2004.
For correspondence or reprints contact: Bryan W. Reutter, Department of Nuclear Medicine and Functional Imaging, E.O. Lawrence Berkeley National Laboratory, University of California, 1 Cyclotron Rd., MS55-121, Berkeley, CA 94720.
E-mail: bwreutter{at}lbl.gov