First in Human Use of Novel 4-Threshold-Mode PCD-CT: Non-Inferiority of Image Quality and Radiation Exposure
2Diagnostic Imaging, Sheba Medical Center
Background:
A novel research 4-threshold scan mode uses photon-counting CT (PCD-CT) technology to count individual X-ray photons and sort them into four energy thresholds, providing four co-registered, simultaneous energy measurements per pixel. This scan mode is currently cleared only for research and lacks FDA approval for routine clinical diagnostic use. Translating this advanced technology into standard clinical practice requires validation of its quality and radiation safety.
Materials and Methods:
We recruited consenting patients undergoing ambulatory chest-abdomen CT scans. Inclusion criteria included a prior CT scan available in our PACS system, performed at our hospital. CT series were acquired using the 4-threshold-mode installed for research use on our PCD-CT (NAEOTOM Alpha, Siemens Healthineers), producing axial series at four energy thresholds, including a combined series spanning the entire energy spectrum.
The combined series were compared with previous scans, and the Signal-to-Noise Ratio (SNR), Contrast-to-Noise Ratio (CNR), and CTDIvol were recorded. An anonymized pairwise analysis was performed for each patient’s scans to compare image quality and noise.
Results:
A total of 32 scans (21 non-contrast-enhanced, 11 contrast-enhanced) were performed in 21 subjects. The inter-rater agreement (Cohen’s Kappa) was 0.29 (p=0.02). The Wilcoxon signed-rank test showed statistically significant improvements in image quality and reduced noise in the 4-threshold-mode (p=0.008 and p=0.01, respectively). Radiation exposure did not differ between previous and current scans (p=0.3, 95% CI -2.4-0.7). SNR was significantly lower in the 4-threshold-mode (p<0.01).
Conclusion:
A first-in-human study of the novel PCD-CT 4-threshold mode demonstrated image quality comparable to prior CT scans while maintaining the same radiation exposure and noise levels. This paves the way for additional clinical research into its previously unexplored features.