Photon-Counting Detector CT Allows Abdominal Virtual Monoenergetic Imaging at Lower Kiloelectron Volt Level with...

Our study aimed to assess the image quality of lower kiloelectron volt (keV) level abdominal virtual monoenergetic imaging (VMI) with lower radiation dose on photon-counting detector computed tomography (PCD-CT), in comparison to energy-integrating detector computed tomography (EID-CT). We prospectively included three matched groups, each with 59 participants, to undergo contrast-enhanced abdominal CT scans using EID-CT with full-dose (EID_FD), PCD-CT with full-dose (PCD_FD), and PCD-CT with low-dose (PCD_LD) protocols, respectively. The data of portal-venous phase were reconstructed into VMI at 40, 50, 60, and 70 keV, respectively. The standard deviation of CT values in liver parenchyma was measured as image noise. The signal-to-noise ratio (SNR) of liver parenchyma and contrast-to-noise ratio (CNR) of liver-portal vein were calculated. Three radiologists assessed the image noise, vessel sharpness, and overall quality, and rated the hepatic lesion conspicuity if possible. Our study found that the PCD_LD significantly reduced the radiation dose than EID_FD or PCD_FD (p < 0.001). The noise was significantly decreased by PCD_FD and PCD_LD compared to EID_FD, but SNR values were significantly increased (p ≤ 0.006). The CNR values were significantly increased by PCD_FD and PCD_LD compared to EID_FD in VMI at 40 keV and 50 keV (p ≤ 0.010). The ratings of image noise, vessel sharpness, overall quality, and lesion conspicuity were significantly greater in PCD_FD and PCD_LD compared to EID_FD (p ≤ 0.001). There was no significant difference detected in rating of lesion conspicuity between PCD_FD and PCD_LD (p ≥ 0.259). In conclusion, PCD-CT allows abdominal VMI with lower keV and lower noise using lower radiation dose, to provide better visualization of the hepatic lesions.