Prospective Evaluation of Reduced Dose Computed Tomography for the Detection of Low-Contrast Liver Lesions: Direct Comparison with Concurrent Standard Dose Imaging
To prospectively compare the diagnostic performance of reduced-dose (RD) contrast-enhanced CT (CECT) with standard-dose (SD) CECT for detection of low-contrast liver lesions.
Seventy adults with non-liver primary malignancies underwent abdominal SD-CECT immediately followed by RD-CECT, aggressively targeted at 60-70 % dose reduction. SD series were reconstructed using FBP. RD series were reconstructed with FBP, ASIR, and MBIR (Veo). Three readers—blinded to clinical history and comparison studies—reviewed all series, identifying liver lesions ≥4 mm. Non-blinded review by two experienced abdominal radiologists—assessing SD against available clinical and radiologic information—established the reference standard.
RD-CECT mean effective dose was 2.01 ± 1.36 mSv (median, 1.71), a 64.1 ± 8.8 % reduction. Pooled per-patient performance data were (sensitivity/specificity/PPV/NPV/accuracy) 0.91/0.78/0.60/0.96/0.81 for SD-FBP compared with RD-FBP 0.79/0.75/0.54/0.91/0.76; RD-ASIR 0.84/0.75/0.56/0.93/0.78; and RD-MBIR 0.84/0.68/0.49/0.92/0.72. ROC AUC values were 0.896/0.834/0.858/0.854 for SD-FBP/RD-FBP/RD-ASIR/RD-MBIR, respectively. RD-FBP (P = 0.002) and RD-MBIR (P = 0.032) AUCs were significantly lower than those of SD-FBP; RD-ASIR was not (P = 0.052). Reader confidence was lower for all RD series (P < 0.001) compared with SD-FBP, especially when calling patients entirely negative.
Aggressive CT dose reduction resulted in inferior diagnostic performance and reader confidence for detection of low-contrast liver lesions compared to SD. Relative to RD-ASIR, RD-FBP showed decreased sensitivity and RD-MBIR showed decreased specificity.
• Reduced-dose CECT demonstrates inferior diagnostic performance for detecting low-contrast liver lesions.
• Reader confidence is lower with reduced-dose CECT compared to standard-dose CECT.
• Overly aggressive dose reduction may result in misdiagnosis, regardless of reconstruction algorithm.
• Careful consideration of perceived risks versus benefits of dose reduction is crucial.
KeywordsDiagnostic imaging Multi-detector computed tomography Radiation dosage Liver Metastases
The scientific guarantor of this publication is PJ Pickhardt. This research was supported by the National Institutes of Health, grant 1R01 CA169331. Dr. Pickhardt is co-founder of VirtuoCTC and shareholder in Cellectar Biosciences, SHINE, and Elucent. Dr. Kim is co-founder of VirtuoCTC, consultant for Viatronix, and on the medical advisory board for Digital Artforms. All other authors declare no relevant disclosures. No complex statistical methods were necessary for this paper. Institutional Review Board approval was obtained. Written informed consent was obtained from all subjects (patients) in this study. Methodology: prospective, case-control study, performed at one institution.
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