Reduced stress dose with rapid acquisition CZT SPECT MPI in a non-obese clinical population: comparison to coronary angiography.

BACKGROUND: Cadmium Zinc Telluride (CZT) SPECT camera technology has the potential to reduce patient's radiation exposure and shorten imaging time. This study evaluated the correlation of low stress tracer dose, rapid CZT SPECT myocardial perfusion imaging (MPI) to coronary angiography in a <200-lbs population to further validate its ability to achieve both goals while preserving diagnostic accuracy. METHODS: All patients who had a low-dose stress (≤15 mCi) Tc-99m sestamibi SPECT MPI study using a CZT camera (GE Discovery NM 530c) with 3- to 5-minute image acquisition over a 2-year period followed by a coronary angiogram within 2 months were included. Patients with a history of coronary revascularization, left ventricular dysfunction, and LBBB or paced rhythms were excluded. Both MPI studies and coronary angiograms were interpreted by blinded readers and coronary artery disease (CAD) was defined as ≥70% stenosis. RESULTS: A total of 71 patients were included with a mean age of 64 years, 55% male, and a BMI of 25.4 kg/m(2) with an average stress dose of 13.3 mCi. Exercise stress was performed in 54% of patients and vasodilator pharmacologic stress in 46%. Sensitivity was 89%, specificity was 66%, and accuracy was 78% for detecting obstructive CAD. CONCLUSIONS: In this group of non-obese patients undergoing low stress dose imaging, high-efficiency CZT SPECT imaging demonstrated a high sensitivity, specificity, and accuracy for detecting obstructive epicardial CAD with a greatly reduced imaging time.

Reduced isotope dose and imaging time with a high-efficiency CZT SPECT camera.

BACKGROUND: In light of recent focus on diagnostic imaging, cardiac SPECT imaging needs to become a shorter test with lower radiation exposure to patients. Recently introduced Cadmium Zinc Telluride (CZT) cameras have the potential to achieve both goals. METHODS: During a 2-month period patients presenting for a Tc-99m sestamibi SPECT MPI study were imaged using a CZT camera using a low-dose rest-stress protocol (5 mCi rest and 15 mCi stress doses). Patients ≥250 lbs or a BMI ≥35 kg/m(2) were excluded. Rest images were processed at 5- and 8-minute acquisition times and stress images at 3- and 5-minute acquisition times. A subset of patients had stress imaging performed using both conventional and CZT SPECT cameras. Image acquisition times and SPECT camera images were compared based on total counts, count rate, image quality, and summed rest and stress scores. Twelve month clinical follow-up was also obtained. RESULTS: 131 patients underwent the study protocol (age 64.9 ± 9.8 years, 54.2% male). There was no significant difference in image quality and mean summed scores between 5- and 8-minute rest images and between 3- and 5-minute stress images. When compared to a conventional SPECT camera in 27 patients, total rest and stress perfusion deficits and calculated LVEF were similar (r = 0.94 and 0.96, respectively). At 12 months there was a benign prognosis in patients with normal perfusion. The effective dose was 5.8 mSv for this protocol which is 49.2% less than conventional Tc-99m studies and 75.7% less than conventional Tl-201/Tc-99m dual isotope studies. CONCLUSIONS: New SPECT camera technology with low isotope dose significantly reduces ionizing radiation exposure and imaging times compared to traditional protocols while maintaining image quality and diagnostic accuracy.

Reduced isotope dose with rapid SPECT MPI imaging: initial experience with a CZT SPECT camera.

BACKGROUND: Cardiac SPECT imaging needs to become shorter and use lower radiation doses to compete with other available noninvasive imaging modalities. Recently introduced cadmium zinc telluride (CZT) SPECT cameras have the potential to achieve both goals, but clinical experience is so far limited. METHODS: Images of all patients undergoing a stress MPI over a 4-month period using a CZT camera (Discovery NM 530c) were reviewed. Patients were divided into three groups based on imaging protocols: low-dose stress-only, high-dose stress-only, and standard dose rest-stress. Low-dose stress-only patients were matched by gender, stressor, and BMI to high-dose stress-only and rest-stress subjects. Stress image quality was graded on a four-point scale by readers blinded to the imaging protocol. Demographics, tracer dose, stress imaging time, and total counts were recorded. RESULTS: Of 717 patients imaged, the mean age was 64.0 years, 50.5% were female, 58.9% underwent exercise stress, and the average BMI was 27.9 kg/m(2). A total of 103 low-dose stress-only patients were matched to controls. Imaging for 5 minutes in low-dose stress-only patients and for 3 minutes in high-dose stress-only and rest-stress patients, resulted in a similar number of total counts. This produced similar image quality in the three groups with a 57% isotope dose reduction in the low-dose stress-only compared to the high-dose stress-only group. CONCLUSION: New SPECT CZT camera technology allows significantly reduced radiation exposure and acquisition time without loss of image quality.