Peritoneal dialysis-related complication: Can diagnostic accuracy be achieved at low iodinated contrast media dose using dual-layer spectral detector CT?

Introduction: Computed tomography peritoneography (CTp) is pivotal for evaluating peritoneal dialysis (PD)-related complications, yet it comes with drawbacks, specifically exposure to iodinated contrast media (ICM). This study aimed to explore the feasibility of reducing ICM dosage utilizing spectral detector CT (SDCT).

Materials and methods: 35 rabbits were strategically divided into 7 groups (A - G) according to the ICM concentration ratio in the injection protocol, with respective doses of 10, 15, 20, 25, 30, 40, and 50 mL/2L. The CTp injection protocol involved a 300-mL mixture of non-ionic ICM omnipaque (350 mgI/mL) and peritoneal dialysate (1.5% lactate, 2 L), followed by scans using dual-layer SDCT. Virtual monoenergetic images (VMIs) at 4 distinct energy levels (40 - 70 keV, in 10-keV steps), iodine maps (IMs), and effective atomic number (Zeff) maps were subsequently reconstructed. Both quantitative and qualitative image assessments were conducted, and the parameters from these analyses were compared across images from groups A - G and traditional 50 mL/2L 120-kVp images. In post-determination of the optimal concentration and reconstructions, we illustrated their applications in patients with suspected PD-related complications.

Results: The quantitative image quality (IQ) of 15 mL/2L VMIs at 40 keV surpassed that of the 50 mL/2L 120-kVp images (p < 0.05). Furthermore, the diagnostic performance utilizing 15 mL/2L VMIs40 keV, when combined with IMs and Zeff maps, was found to be optimal.

Conclusion: The employment of SDCT in CTp allows for a substantial reduction in the ICM dose by 70%, compared to the benchmark concentration of 50 mL/2L, without compromising diagnostic precision.