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

Abstract

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.