Effect of a patient-specific minimum activity in stress myocardial perfusion imaging using CZT-SPECT: Prognostic value, radiation dose, and scan outcome

Abstract

Background. SPECT Myocardial perfusion imaging (MPI) is associated with a relatively high radiation burden and decreasing image quality in heavy patients. Patient-specific low-activity protocols (PLAPs) are suggested but follow-up data is lacking. Our aim was to compare the use of a standard fixed-activity protocol (FAP) with a PLAP in cadmium zinc telluride (CZT)-SPECT MPI.Methods. We retrospectively included 1255 consecutive patients who underwent CZT-SPECT stress-optional rest MPI. 668 Patients were scanned using FAP (370 MBq) and 587 patients using PLAP (2.25 MBq·kg −1 ). Percentage of scans interpreted as normal, radiation dose, and 1-year follow-up including hard event rates (all-cause death or non-fatal myocardial infarction) were collected and compared.Results. The percentage of scans interpreted as normal was 67% in FAP and 70% in PLAP groups (P = .29). The annualized hard event rates in these patients were 1.0% in the FAP and 0.9% in the PLAP group (P = .86). However, the mean radiation dose decreased by 23% for stress-only and by 15% to 2.6 mSv for stress-optional rest MPI after introduction of the PLAP (p<0.001).Conclusions. Introduction of a patient-specific low-activity protocol does not affect the percentage of scans interpreted as normal or prognosis but significantly lowers the radiation dose for CZT-SPECT MPI. (J Nucl Cardiol 2018;25:26-35.) Spanish AbstractAntecedentes. El estudio de imagen de perfusión miocárdica con SPECT (MPI, por sus siglas en ingles) se asocia con una carga de radiación relativamente alta y una menor calidad de imagen en pacientes obesos. Se sugieren protocolos de baja actividad específica para cada pacientes (PBAP), sin embargo faltan datos de seguimiento. Nuestro objetivo fue comparar el uso de un protocolo con actividad fija estándar (PAF) con un PBAP en un estudio de perfusión miocárdica con SPECT CZT cadmio-zinc-telurio. Métodos. Incluimos de manera retrospectiva 1255 pacientes consecutivos que se sometieron a un SPECT CZT de estrés con fase de reposo de manera opcional. 668 pacientes fueron escaneados usando un PAF (370 MBq) y 587 pacientes utilizando un PBAP (2.25 MBq/kg). Los porcentajes de exploraciones interpretadas como normales, dosis de radiación y seguimiento de un año incluyendo tasas de eventos duros (muerte por todas las causas o infarto de miocardio no fatal) fueron recolectados y comparados.Resultados. El porcentaje de exploraciones interpretadas como normales fue de 67% en el PAF y de 70% en el PBAP (p = 0.29). Las tasas de eventos duros anuales en estos pacientes fueron del 1.0% en el PAF y del 0.9% en el PBAP (p = 0.86). Sin embargo, la dosis de radiación media disminuyó en un 23% para los estudios de solo estrés y en un 15% para 2.6 mSv en el estudio de estrés con reposo opcional después de la introducción del PBAP (p <0,001).Conclusiones. La introducción de un protocolo de baja actividad específica para el paciente no afecta el porcentaje de estudios interpretados como normal o el pronóstico, sin embargo reduce significativamente la dosis de ra...

A position sensitive scintillation detector using a side-by-side GAGG-F/GAGG-T phoswich block

“…However, the LYSO scintillator containing 176 Lu has background radiation, which will introduce noise events [15]. Although 176 Lu background radiation may not significantly influence the performance of common ECT applications [4,16,17], however, it reduces the imaging quality and restricts the application in low-activity imaging [18][19][20].…”

The next step in standardizing SPECT myocardial perfusion imaging

“…8 Yet, it has been shown that weightbased SPECT MPI protocols result in either an improved overall image quality or a comparable image quality while administering a lower activity. 9,10 Adopting a count-based patient-specific activity or scan-time protocol results in a constant image quality across patients but does not account for all factors that determine the image quality of SPECT MPI and are therefore often center specific.…”

Effect of reduced photon count levels and choice of normal data on semi-automated image assessment in cardiac SPECT: Doing more with fewer counts

“…Yet, investigations on the effect of dose reduction and normal database selection compared to standard MPI protocols, particularly in the same patient population, remain limited. [5][6][7] In the present issue of Journal of Nuclear Cardiology, Wetzl et al 8 addressed the crucial issue of normal database selection in the context of low-dose imaging protocols. In fact, in addition to the well-known parameters affecting the normal database definition and creation such as tracer, type of camera, clinical protocol, and gender, the count level may be a further source of inconsistency between patient's data and normal reference and ultimately introduce bias into perfusion quantification.…”