Quantification of myocardial flow reserve using a gamma camera with solid-state cadmium-zinc-telluride detectors: Relation to angiographic coronary artery disease.

BACKGROUND: Previous studies have suggested using gamma cameras with cadmium-zinc-telluride (CZT) detectors to quantify myocardial blood flow (MBF) and flow reserve (MFR). In this study, we aimed to evaluate the feasibility and accuracy of MFR quantification using a CZT camera compared to coronary angiography. METHODS: Forty-one participants referred for coronary angiography underwent a rest/stress one-day myocardial perfusion imaging protocol using a CZT gamma camera. Rest and stress dynamic phases were followed by acquisition of traditional perfusion images and time-activity curves were generated. Angiographic and perfusion results were compared to MFR. RESULTS: Patients with abnormal perfusion presented reduced MFR (2.01 [1.48-2.77] vs. 2.94 [2.38-3.64], P = 0.002), and reduced stress MBF. Patients with high-risk CAD had lower global MFR compared to patients without obstructive disease (1.99 [1.22-2.84] vs. 2.89 [2.22-3.58], P = 0.026). Obstructed vessels showed lower regional MFR when compared to non-obstructed (1.81 [1.19-2.67] vs. 2.75 [2.13-3.42], P < 0.001). A regional MFR of 2.2 provided a sensitivity of 63.2% and specificity of 74.1% to identify an obstructive lesion in the corresponding artery. CONCLUSION: In patients undergoing invasive coronary angiography for the evaluation of CAD, quantifying MBF and MFR in a CZT gamma camera is feasible and reflects underlying disease. In these patients, reduced regional MFR suggests the presence of obstructive lesion(s).

Prognostic value of a faster, low-radiation myocardial perfusion SPECT protocol in a CZT camera.

To determine the prognostic value of a new, ultrafast, low dose myocardial perfusion SPECT (MPS) protocol in a cadmium-zinc telluride (CZT) camera. CZT cameras have introduced significant progress in MPS imaging, offering high-quality images despite lower doses and scan time. Yet, it is unknown if, with such protocol changes, the prognostic value of MPS is preserved. Patients had a 1-day 99 m-Tc-sestamibi protocol, starting with the rest (185-222 MBq) followed by stress (666-740 MBq). Acquisition times were 6 and 3 min, respectively. MPS were classified as normal or abnormal perfusion scans and summed scores of stress, rest, and difference (SSS, SRS and SDS), calculated. Patients were followed with 6-month phone calls. Hard events were defined as death or nonfatal myocardial infarction. Late revascularization was that occurring after 60 days of MPS. 2930 patients (age 64.0 ± 12.1 years, 53.3% male) were followed for 30.7 ± 7.5 months. Mean dosimetry was 6 mSv and mean total study time, 48 ± 13 min. The annual hard event and late revascularization rate were higher in patients with greater extension of defect and ischemia. SSS was higher in patients with hard events compared to those without events (2.6 ± 4.9 vs. 5.0 ± 6.3, p < 0.001), as well as the SDS (0.7 ± 1.9 vs. 1.7 ± 3.4, p < 0.00). The same was true for patients with or without late revascularization (SSS: 2.5 ± 4.7 vs. 6.6 ± 7.1; SDS: 0.6 ± 1.7 vs. 2.9 ± 3.8, p < 0.01). A new, faster, low-radiation, MPS protocol in a CZT camera maintain the ability to stratify patients with increased risk of events, showing that, in the presence of greater extension of defect or ischemia, patients presented higher rates of hard events and late revascularization.

Comparison of myocardial T1 and T2 values in 3 T with T2* in 1.5 T in patients with iron overload and controls.

Myocardial iron quantification remains limited to 1.5 T systems with T2* measurement. The present study aimed at comparing myocardial T2* values at 1.5 T to T1 and T2 mapping at 3.0 T in patients with iron overload and healthy controls. A total of 17 normal volunteers and seven patients with a history of myocardial iron overload were prospectively enrolled. Mid-interventricular septum T2*, native T1 and T2 times were quantified on the same day, using a multi-echo gradient-echo sequence at 1.5 T and T1 and T2 mapping sequences at 3.0 T, respectively. Subjects with myocardial iron overload (T2* < 20 ms) in comparison with those without had significantly lower mean myocardial T1 times (868.9 ± 120.2 vs. 1170.3 ± 25.0 ms P = 0.005 respectively) and T2 times (34.9 ± 4.7 vs. 45.1 ± 2.0 ms P = 0.007 respectively). 3 T T1 and T2 times strongly correlated with 1.5 T, T2* times (Pearson's r = 0.95 and 0.91 respectively). T1 and T2 measures presented less variability than T2* in inter- and intra-observer analysis. Native myocardial T1 and T2 times at 3 T correlate closely with T2* times at 1.5 T and may be useful for myocardial iron overload quantification.

Prognostic evaluation in obese patients using a dedicated multipinhole cadmium-zinc telluride SPECT camera.

The purpose of this study is to evaluate the prognostic value of myocardial perfusion SPECT obtained in CZT cameras (CZT-SPECT) with multipinhole collimation in obese patients. CZT-SPECT may be technically challenging in the obese, and its prognostic value remains largely unknown. Patients underwent single-day, rest/stress (supine and prone) imaging. Images were visually inspected and graded as poor, fair or good/excellent. Summed stress and difference scores (SSS and SDS, respectively) were converted into percentages of total perfusion defect and of ischemic defect by division by the maximum possible score. Obesity was defined as a body mass index (BMI) ≥ 30 kg/m(2) and classified as class I (BMI 30-34.9 kg/m(2)), II (BMI 35-39.9 kg/m(2)), or III (BMI ≥ 40 kg/m(2)). Patients were followed-up by telephone interview for the occurrence of all-cause death, myocardial infarction or revascularization. A Cox proportional hazards analysis was used to assess the independent predictors of death. Among 1396 patients, 365 (26.1 %) were obese (mean BMI 33.9 ± 3.6; 17.5 % class I, 3.4 % class II, and 3.4 % class III). Image quality was good/excellent in 94.5 % of the obese patients. The annualized mortality rates were not significantly different among obese and non-obese patients, being <1 % with normal CZT-SPECT, and increased with the degree of scan abnormality in both obese and non-obese patients. Age, the use of pharmacologic stress and an abnormal CZT-SPECT, but not obesity, were independent predictors of death. In obese patients, single-day rest/stress CZT-SPECT with a multipinhole camera provides prognostic discrimination with high image quality.

Biodistribution of bone marrow mononuclear cells in chronic chagasic cardiomyopathy after intracoronary injection.

BACKGROUND: Animal and human clinical studies have indicated that bone marrow (BM) mononuclear cell (MNC) therapy for Chagasic Cardiomyopathy (ChC) is feasible, safe and potentially efficacious. Nevertheless, little is known about the retention of these cells after intracoronary (IC) infusion. METHODS: Our study investigated the homing of technetium-99m ((99m)Tc) labeled BM MNCs and compared it to thallium-201 ((201)Tl) myocardial perfusion images using the standard 17-segment model. Six patients with congestive heart failure of chagasic etiology were included. RESULTS: Scintigraphic images revealed an uptake of 5.4%±1.7, 4.3%±1.5 and 2.3%±0.6 of the total infused radioactivity in the heart after 1, 3 and 24h, respectively. The remaining activity was distributed mainly to the liver and spleen. Of 102 segments analyzed, homing took place in 36%. Segments with perfusion had greater homing (58.6%) than those with decreased or no perfusion (6.8%), p<0.0001. There was no correlation between the number of injected cells and the number of segments with homing for each patient (r=-0.172, p=0.774). CONCLUSIONS: These results indicate that (99m)Tc-BM MNCs delivered by IC injection homed to the chagasic myocardium. However, cell biodistribution was heterogeneous and limited, being strongly associated with the myocardial perfusion pattern at rest. These initial data suggest that the IC route may present limitations in chagasic patients and that alternative routes of cell administration may be necessary.