Minimum Clinically Achievable Dose for Detecting Liver Lesions Using Deep Learning Image Reconstruction: A Phantom and Patient Study.
Authors
Affiliations (3)
Affiliations (3)
- Radiology Department, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China (Z.P., M.X., T.Q, Y.Z., L.Z., Q.L., X.X).
- CT Imaging Research Center, GE Healthcare China, Shanghai, China (L.L., X.S., J.L., S.Z.).
- Radiology Department, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China (Z.P., M.X., T.Q, Y.Z., L.Z., Q.L., X.X). Electronic address: [email protected].
Abstract
To investigate the performance of deep learning image reconstruction (DLIR) at an ultra-low dose of approximately 4.5 mGy for detecting focal liver lesions (FLLs), in comparison with adaptive statistical iterative reconstruction-V (ASIR-V) at standard doses (10-15 mGy), through both phantom and prospective patient studies. A Gammex CT phantom (simulating FLLs with iodine concentrations 2.0-20 mg/mL and normal liver density 1.06 g/cm<sup>3</sup>) was scanned using DLIR (4.5 mGy) and ASIR-V (10 and 15 mGy). Quantitative metrics included image noise, signal-to-noise ratio, contrast-to-noise ratio, noise power spectrum peak (NPS<sub>peak</sub>), and detectability index. In a prospective single-center study, 84 participants (mean age 64 ± 12 years, IQR 60-69 years; 48 males) underwent triple-phase upper-abdominal CT (target dose: 4.5 mGy/phase). Images were reconstructed with DLIR and ASIR-V. Two radiologists blindly evaluated image quality (5-point scale), FLL detectability, sensitivity, and specificity. The reference standard for detectability included histopathology, 3-month standard-dose CT, or MRI. In the phantom study, DLIR at 4.5 mGy outperformed ASIR-V at 10 mGy across all quantitative metrics (P < 0.001) and exceeded ASIR-V at 15 mGy in noise and NPS<sub>peak</sub> (P < 0.05). Clinically, 71 FLLs (mean size 12.8 ± 10 mm; 55 benign, 16 malignant) were identified. The median CTDI<sub>vol</sub> was 4.64 mGy (50% to 70% lower than standard doses). DLIR showed superior qualitative image quality vs. ASIR-V (1.25 mm slices: 3.9 ± 0.6 vs. 2.2 ± 0.4, P < 0.001) and higher FLL detection rate (93.0% vs. 77.5%, P < 0.001), with sensitivity 90.1% and specificity 75.0% (both higher than ASIR-V, P < 0.001). DLIR at 4.5 mGy achieves substantial radiation dose reduction while providing superior FLL detection performance compared to ASIR-V at 10-15 mGy. This protocol offers a safe and accurate option for FLL screening and follow-up.