Agneta Gustafsson

The accuracy of quantitative parameters in (99m) Tc-MAG3 dynamic renography: a national audit based on virtual image data.

Assessment of image analysis methods and computer software used in 99mTc‐MAG3 dynamic renography is important to ensure reliable study results and ultimately the best possible care for patients. In this work, we present a national multicentre study of the quantification accuracy in 99mTc‐MAG3 renography, utilizing virtual dynamic scintigraphic data obtained by Monte Carlo‐simulated scintillation camera imaging of digital phantoms with time‐varying activity distributions. Three digital phantom studies were distributed to the participating departments, and quantitative evaluation was performed with standard clinical software according to local routines. The differential renal function (DRF) and time to maximum renal activity (Tmax) were reported by 21 of the 28 Swedish departments performing 99mTc‐MAG3 studies as of 2012. The reported DRF estimates showed a significantly lower precision for the phantom with impaired renal uptake than for the phantom with normal uptake. The Tmax estimates showed a similar trend, but the difference was only significant for the right kidney. There was a significant bias in the measured DRF for all phantoms caused by different positions of the left and right kidney in the anterior–posterior direction. In conclusion, this study shows that virtual scintigraphic studies are applicable for quality assurance and that there is a considerable uncertainty associated with standard quantitative parameters in dynamic 99mTc‐MAG3 renography, especially for patients with impaired renal function.

Evaluation of inter-departmental variability of ejection fraction and cardiac volumes in myocardial perfusion scintigraphy using simulated data

BackgroundMyocardial perfusion scintigraphy (MPS) is a clinically useful noninvasive imaging modality for diagnosing patients with suspected coronary artery disease. By utilizing gated MPS, the end diastolic volume (EDV) and end systolic volume (ESV) can be measured and the ejection fraction (EF) calculated, which gives incremental prognostic value compared with assessment of perfusion only. The aim of this study was to evaluate the inter-departmental variability of EF, ESV, and EDV during gated MPS in Sweden.MethodsSeventeen departments were included in the study. The SIMIND Monte Carlo (MC) program together with the XCAT phantom was used to simulate three patient cases with different EDV, ESV, and EF. Individual simulations were performed for each department, corresponding to their specific method of performing MPS. Images were then sent to each department and were evaluated according to clinical routine. EDV, ESV, and EF were reported back.ResultsThere was a large underestimation of EDV and ESV for all three cases. Mean underestimation for EDV varied between 26% and 52% and for ESV between 15% and 60%. EF was more accurately measured, but mean bias still varied between an underestimation of 24% to an overestimation of 14%. In general, the intra-departmental variability for EDV, ESV, and EF was small, whereas inter-departmental variability was larger.ConclusionsLeft ventricular volumes were generally underestimated, whereas EF was more accurately estimated. There was, however, large inter-departmental variability.