Impact of a reduced iodine load with deep learning reconstruction on abdominal MDCT

Abstract

To evaluate the impact of a reduced iodine load using deep learning reconstruction (DLR) on the hepatic parenchyma compared to conventional iterative reconstruction (hybrid IR) and its consequence on the radiation dose and image quality. This retrospective monocentric intraindividual comparison study included 66 patients explored at the portal phase using different multidetector computed tomography parameters: Group A, hybrid IR algorithm (hybrid IR) and a nonionic low-osmolality contrast agent (350 mgI/mL); Group B, DLR algorithm (DLR) and a nonionic iso-osmolality contrast agent (270 mgI/mL). We recorded the attenuation of the liver parenchyma, image quality, and radiation dose parameters. The mean hounsfield units (HU) value of the liver parenchyma was significantly lower in group B, at 105.9 ± 10.9 HU versus 118.5 ± 14.6 HU in group A. However, the 90%IC of mean liver attenuation in the group B (DLR) was between 100.8 HU and 109.3 HU. The signal-to-noise ratio of the liver parenchyma was significantly higher on DLR images, increasing by 56%. However, for both the contrast-to-noise ratio (CNR) and CNR liver/PV no statistical difference was found, even if the CNR liver/PV ratio was slightly higher for group A. The mean dose-length product and computed tomography dose index volume values were significantly lower with DLR, corresponding to a radiation dose reduction of 36% for the DLR. Using a DLR algorithm for abdominal multidetector computed tomography with a low iodine load can provide sufficient enhancement of the liver parenchyma up to 100 HU in addition to the advantages of a higher image quality, a better signal-to-noise ratio and a lower radiation dose.

Figure 1.

Flow chart shows the study design with exclusion and inclusion criteria.

Figure 2.

Comparison of the images obtained at the same level in a 65-yr-old woman who underwent a follow-up CT for breast carcinoma. The size and localization of ROI were the same. Note the significantly better image quality achieved with advanced intelligent clear- IQ engine (AiCE). (A) Group A with adaptive iterative dose reduction 3-dimensional (AIDR 3D) (hybrid IR) reconstruction technique − ROI mean value = 115.3 ± 12.3 hounsfield units (HU). Dose-length product (DLP) = 258.4 mGy.cm; signal-to-noise ratio (SNR) = 13.88. (B) Group B with the AICE deep learning reconstruction (DLR) reconstruction technique − ROI mean value = 104.5 ± 9.5 HU. DLP = 353.2 mGy.cm; SNR = 5.85.

Figure 3.

Box plot showing the liver parenchyma mean HU value of the 2 groups. Group A: adaptive iterative dose reduction 3-dimensional (AIDR3D) (hybrid IR). Group B: advanced intelligent clear- IQ engine (AiCE) deep learning reconstruction (DLR).

Figure 4.

Box plot showing the radiation dose parameters deep learning reconstruction (DLR) and computed tomography dose index volume (CTDIvol). Group A: adaptive iterative dose reduction 3-dimensional (AIDR3D) (hybrid IR). Group B: advanced intelligent clear- IQ engine (AiCE) deep learning reconstruction (DLR).