Image quality and radiation dose of renal perfusion CT with low-dose contrast agent: a comparison with conventional CT using a 320-row system

Abstract

To compare perfusion computed tomography (CT) with reconstructed image from source data using low-dose contrast agent and conventional 320-row CT for the evaluation of renal tumours. Twenty-eight patients underwent conventional CT (C-CT) and 26 patients underwent perfusion CT with low-dose (40 ml) contrast agent. Image noise, arterial visualisation, the sharpness of the corticomedullary junction (CMJ), and overall image quality were each assessed using a four-point scale. The tumour detection rate for lesions <4 cm (n=66) was also evaluated. Quantitative image parameters including image noise and the contrast-to-noise ratios (CNRs) of the renal artery and CMJ were measured. The volume CT dose index (CTDI), dose-length product (DLP), and size-specific dose estimate (SSDE) were also recorded. Although the image noise of perfusion CT was higher than that of C-CT and the overall image quality of perfusion CT was lower than that of C-CT, the arterial visualisation score of perfusion CT was significantly higher than that of C-CT. The CMJ sharpness scores of the two techniques were equivalent. Sensitivity and positive predictive values were also equivalent with respect to tumour detection. The CNRs of both the left and right renal arteries were significantly higher on perfusion CT than on C-CT. The CTDI, DLP, and SSDE of perfusion CT were significantly lower than those of C-CT. Perfusion CT using low-dose contrast agent preserved arterial visualisation and the tumour detection rate and achieved a low radiation dose despite image quality degradation and image noise.