Conventional Myocardial Perfusion Imaging Research Articles

Systolic 3D first-pass myocardial perfusion MRI: Comparison with diastolic imaging in healthy subjects

Three-dimensional (3D) first-pass myocardial perfusion imaging (MPI) is a promising alternative to conventional two-dimensional multislice MPI due to its contiguous spatial coverage that is beneficial for estimating the size of perfusion defects. Data acquisition at mid-diastole is a typical choice for 3D MPI yet is sensitive to arrhythmia and variations in R-R interval that are common in cardiac patients. End systole is the second longest quiescent cardiac phase and is known to be less sensitive to the R-R variability. Therefore, 3D MPI with systolic acquisition may be advantageous in patients with severe arrhythmia once it is proven to be comparable to diastolic MPI in subjects with negligible R-R variation. In this work, we demonstrate the feasibility of 3D MPI with systolic data acquisition in five healthy subjects. We performed 3D MPI experiments in which 3D perfusion data were acquired at both end-systole and mid-diastole of every R-R interval and analyzed the similarity between resulting time intensity curves (TIC) from the two data sets. The correlation between systolic and diastolic TICs was extremely high (mean = 0.9841; standard deviation = 0.0166), and there was a significant linear correlation between the two time intensity curve upslopes and peak enhancements (P < 0.001).

Ultrafast nuclear myocardial perfusion imaging on a new gamma camera with semiconductor detector technique: first clinical validation

To assess the diagnostic performance of a novel ultrafast cardiac gamma camera with cadmium-zinc-telluride (CZT) solid-state semiconductor detectors for nuclear myocardial perfusion imaging (MPI). The study group comprised 75 consecutive patients (55 men, BMI range 19-45 kg/m(2)) who underwent a 1-day (99m)Tc-tetrofosmin adenosine-stress/rest imaging protocol. Scanning was performed first on a conventional dual-detector SPECT gamma camera (Ventri, GE Healthcare) with a 15-min acquisition time each for stress and rest. All scans were immediately repeated on an ultrafast CZT camera (Discovery 530 NMc, GE Healthcare) with a 3-min scan time for stress and a 2-min scan time for rest. Clinical agreement (normal, ischaemia, scar) between CZT and SPECT was assessed for each patient and for each coronary territory using SPECT MPI as the reference standard. Segmental myocardial tracer uptake values (percent of maximum) using a 20-segment model and left ventricular ejection fraction (EF) values obtained using CZT were compared with those obtained using conventional SPECT by intraclass correlation and by calculating Bland-Altman limits of agreement. There was excellent clinical agreement between CZT and conventional SPECT on a per-patient basis (96.0%) and on a per-vessel territory basis (96.4%) as shown by a highly significant correlation between segmental tracer uptake values (r=0.901, p<0.001). Similarly, EF values for both scanners were highly correlated (r=0.976, p<0.001) with narrow Bland-Altman limits of agreement (-5.5-10.6%). The novel CZT camera allows a more than fivefold reduction in scan time and provides clinical information equivalent to conventional standard SPECT MPI.

New protocol of myocardial SPECT imaging with technetium-99m sestamibi for reducing the time interval between rest and adenosine stress phases

We have developed a new protocol of myocardial perfusion-gated single-photon emission computed tomography (SPECT), by use of technetium-99m sestamibi (MIBI), in which SPECT imaging at rest followed by SPECT imaging after adenosine with low level ergometer stress can be conducted by use of the Monzen position within a shortened total testing time of 1 h or less. The study group consisted of 137 patients who underwent this new imaging protocol. The diagnostic quality of the images was as good as that of images obtained with the conventional method (30-60 min after the injection of MIBI). The SPECT image quality for the 137 patients was evaluated, and the percentages of images rated as excellent, good, fair, and poor were 65.3, 27.4, 5.8, and 1.5% for the rest image, and 68.2, 21.9, 8.4, and 1.5% for the stress image, respectively. The shortened total testing time reduced the physical and mental burden on the patient compared with that of conventional myocardial perfusion imaging. Because this technique allows us to perform rest and stress myocardial imaging within a short period, it is expected to be very useful in the clinical setting.

Myocardial Perfusion Imaging With 99m Tc Tetrofosmin

Background Our objective was to compare the sensitivity and specificity of tetrofosmin, a new 99m Tc-labeled myocardial perfusion imaging agent for the detection of myocardial perfusion abnormalities, with those of 201 Tl and coronary angiography. Our hypothesis was that same-day stress/rest tetrofosmin imaging could provide data comparable to those of 201 Tl imaging. Myocardial perfusion imaging plays an important role for the evaluation of coronary artery disease. Newer 99m Tc-labeled agents offer several advantages over 201 Tl, the conventional myocardial perfusion imaging agent. Tetrofosmin is a new 99m Tc-labeled agent with promising results in preliminary studies. Methods and Results Two hundred fifty-two patients with suspected coronary artery disease were enrolled in 10 centers in the United States and Europe. All patients underwent exercise and rest myocardial perfusion imaging with 99m Tc-tetrofosmin using two separate injections of the radiotracer 4 hours apart on the same day. Planar images were obtained in three standard views 15 to 60 minutes after radiotracer injection. Patients also underwent standard exercise and redistribution planar 201 Tl imaging within 2 weeks of tetrofosmin imaging. In addition, 58 healthy subjects with low likelihood of coronary artery disease underwent exercise and rest tetrofosmin imaging. Coronary angiograms were available in 181 patients with suspected coronary artery disease. All radionuclide images were processed in the central core laboratory and interpreted blindly by a panel of four experienced readers. 201 Tl images and tetrofosmin images were read separately. Discrepancies were resolved by consensus. The workload, peak heart rate, and double products were comparable during exercise for both imaging agents. Technically acceptable paired 201 Tl and tetrofosmin images were available in 224 of 252 patients. Tetrofosmin images were generally of good quality, with low extracardiac activity, and easy to interpret. Patients were categorized as showing normal, ischemia, infarction, or mixture with each imaging modality. Precise concordance for each of these categories was 59.4% (κ=0.44; 95% CI, 0.35 to 0.53). When patients were categorized as normal or abnormal, the concordance was 80.4% (κ=0.55; 95% CI, 0.43 to 0.67). When each of five anatomic territories (septal, anterior, inferior, lateral, and apical) was categorized as normal versus abnormal, the concordance varied from 81% to 90%. When similar comparison was made for the specific category of abnormality, the concordance was 64% to 84%. When coronary angiography was used as the criterion, the sensitivity and positive and negative predictive accuracy of tetrofosmin and 201 Tl were comparable. The normalcy rate of tetrofosmin images in the healthy subjects with low likelihood of coronary artery disease was 97%. Conclusions 99m Tc tetrofosmin is a new myocardial imaging agent with favorable imaging characteristics with results comparable to those of 201 Tl.