# Low-dose corticomedullary phase CT urography with artificial intelligence iterative reconstruction for bladder cancer evaluation

## TL;DR

This study shows that using AI to reconstruct low-dose CT images can reduce radiation exposure by 80% while still reliably detecting bladder cancer.

## Contribution

Demonstrates the feasibility of low-dose CT urography with AI reconstruction for bladder cancer diagnosis.

## Key findings

- Low-dose AIIR reduced radiation exposure by 80.2% compared to routine-dose scans.
- AIIR outperformed HIR in image quality and diagnostic accuracy for bladder cancer.
- AIIR achieved comparable diagnostic performance to routine-dose HIR.

## Abstract

To test the feasibility and quantify the performance of low-dose CT urography (CTU) with artificial intelligence iterative reconstruction (AIIR) for bladder cancer (BC) evaluation.

A total of 122 patients undergoing CTU examination were prospectively enrolled, where the routine-dose scan (120 kVp, ref 100 mAs) at corticomedullary phase (CMP) was followed immediately by a low-dose scan (120 kVp, ref 20 mAs). Routine-dose images were reconstructed with hybrid iterative reconstruction (HIR, RD-HIR), while low-dose images were with AIIR (LD-AIIR) and HIR (LD-HIR). The image quality was first evaluated regarding streak artefacts around the bladder and then in contrast-to-noise ratio (CNR) for various manifestations of bladder wall. The diagnostic performance of BC was characterized using receiver operating characteristic (ROC) analysis, in respect to the clinical diagnostic report.

The effective dose at low-dose CMP was 80.2% lower than routine-dose scan (7.6 ± 1.2 vs 1.5 ± 0.3 mSv). Nineteen cases in LD-HIR were deemed clinically unacceptable for presenting severe artefacts around the bladder, while found well above the basic requirement in LD-AIIR. The highest CNR was found in LD-AIIR in all scenarios (all P < .001). The area under ROC curve in LD-AIIR was comparable to RD-HIR (0.988 vs 0.990, P = .172) and significantly higher than LD-HIR (0.988 vs 0.831, P < .001).

The low-dose AIIR protocol allows for a profound dose reduction (80.2%) while maintaining reliable diagnosis of BC on corticomedullary phase CTU images.

Corticomedullary phase CTU with AIIR permits 80.2% dose reduction while preserving reliable BC diagnosis.