Comparison of ⁹⁹mTc-N-DBODC5 and ⁹⁹mTc-MIBI of myocardial perfusion imaging for diagnosis of coronary artery disease

Abstract

Despite recent advances in therapeutic and diagnostic approaches, coronary artery disease (CAD) and its related cardiac disorders represent the most common cause of death in the United States. Nuclear myocardial perfusion imaging (MPI) technologies play a pivotal role in the diagnosis and treatment design for CAD. Recently, in order to develop improved MPI agents for diagnosis of CAD, (99m)Tc-[bis(dimethoxypropylphosphinoethyl)-ethoxyethyl-amine(PNP5)]-[bis(N-ethoxyethyl)dithiocarbamato(DBODC)]nitride(N-DBODC5)((99m)Tc-N-DBODC5) with a faster liver clearance than conventional single-photon emission computed tomography (SPECT) imaging agents (technetium 99m sestamibi ((99m)Tc-MIBI) or technetium 99m tetrofosmin) has been introduced. In preclinical and phase I studies, (99m)Tc-N-DBODC5 has shown characteristics of an essentially ideal MPI tracer. Importantly, however, there is no data to support the use of (99m)Tc-N-DBODC5 to evaluate myocardial ischemia in patients with suspected CAD. The present study was designed to assess the clinical value of this agent; the findings of stress and rest MPI after the administration of this agent were compared to those of stress and rest (99m)Tc-MIBI, as well as those of coronary angiography, with respect to the detection of CAD. Our findings indicated the usefulness of (99m)Tc-N-DBODC5 as a promising MPI agent.

Figure 1

^99mTc-N-DBODC5 and ^99mTc-MIBI imaging protocols: two-day exercise stress/rest.

Figure 2

Comparison of liver clearance of the two tracers in anterior tomographic planar images of a patient (as shown in the black arrow; H, heart; Lv, liver). (a) Exercise stress ^99mTc-N-DBODC5, (b) Exercise stress ^99mTc-MIBI, (c) rest ^99mTc-N-DBODC5 and (d) rest ^99mTc-MIBI.

Figure 3

Heart-to-liver ratio and heart-to-intestine ratio measured with an anterior projection images at stress for 30 min and rest for 60 min for ^99mTc-N-DBODC5 and ^99mTc-MIBI in 46 patients.

Figure 4

Abnormal MPI in the vertical long-axis slices of a representative patient. Both ^99mTc-N-DBODC5 (a) and ^99mTc-MIBI (b) images demonstrate an inferoposterior defect (white arrows). The defect is well visualized on two tracer images corresponding to the CA result. This coronary angiography (c) detected a stenosis of 90% in the RCA. The concordance for diagnosis of myocardial ischemia was seen on ^99mTc-N-DBODC5 and ^99mTc-MIBI studies.

Figure 5

Serial short-axis and vertical long-axis slices of stress-rest ^99mTc-N-DBODC5 images (b) and stress-rest ^99mTc-MIBI images (c) of a representative patient with normal CA (a). Because of intense uptake of technetium ^99mTc-MIBI in the liver, high liver background activity can be observed. Furthermore, a false-positive myocardial perfusion defect was also seen in the inferoposterior wall segments supplied by the RCA territory (white arrows). Importantly, however, at stress and rest, the inferoposterior wall segments of ^99mTc-N-DBODC5 images are clearly separated from the subdiaphragmatic activity.