Radiology · Medical Literature
Assessing Image Quality and Diagnostic Performance of Quadruple-Low Coronary CT Angiography with Deep Learning in High-BMI Patients.
Abstract
To examine the feasibility of a quadruple-low protocol in coronary computed tomography angiography (CCTA) assisted by the deep learning image reconstruction (DLIR) for participants with high body mass index (BMI). This prospective study involved 180 participants (BMI of ≥ 25 kg/m2). Participants were randomly assigned to three groups: the standard-dose (SD) group in 100 kVp with adaptive statistical iterative reconstruction (ASIR-V 50%) using contrast media (CM) administration at an iodine load of 245 mgI/kg (Iohexol, 350 mgI/mL) with a 10 s injection time; the experimental group underwent imaging with 80 kVp and DLIR-H, using an iodine load of 128 mgI/kg with a 7 s injection time, representing the triple-low (TL) with 350 mgI/mL Iohexol and quadruple-low (QL) groups with 320 mgI/mL Iodixanol. Quantitative image quality evaluations included vascular attenuation, image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR), while qualitative image quality and diagnostic performance were also assessed. Compared to the SD group, the TL group achieved reductions of 29.4% in radiation dose, 47.5% in CM volume, and 23.5% in CM injection rate, while the QL group achieved reductions of 32.5% in radiation dose, 41.5% in CM volume, 14.5% in CM injection rate, and 9% in CM concentration. The image noise in the QL and TL groups were significantly lower than in the SD group (all p 0.05). TL and QL CCTA protocols showed equivalent or superior image quality and diagnostic accuracy compared to the SD protocol and may serve as effective alternatives for reducing radiation dose and contrast media use in patients with high BMI.
Clinical relevance
In overweight and obese patients (BMI ≥ 25 kg/m²) undergoing coronary CT angiography (CCTA), can a quadruple-low protocol—combining 80 kVp tube voltage, reduced iodine load (128 mgI/kg), shortened injection time, and low-concentration contrast media (320 mgI/mL iodixanol)—with deep learning image reconstruction (DLIR-H) achieve non-inferior image quality and diagnostic performance compared to a standard-dose protocol? __SNAPSHOT__ {"studyDesign":"Prospective, randomized, three-arm comparative study","setting":"Not reported (single institution implied; country not specified in abstract)","sampleSize":"n=180 (Standard-Dose [SD] group, Triple-Low [TL] group, and Quadruple-Low [QL] group; n per arm not reported in the provided abstract excerpt)","population":"Adults with BMI ≥ 25 kg/m² referred for coronary CT angiography; specific age range, sex distribution, and cardiac risk profile not reported in the provided abstract excerpt","intervention":"Quadruple-Low (QL) protocol: 80 kVp, DLIR-H reconstruction, iodine load of 128 mgI/kg, 7-second injection time, low-concentration contrast media (iodixanol 320 mgI/mL); Triple-Low (TL) protocol: 80 kVp, DLIR-H reconstruction, iodine load of 128 mgI/kg, 7-second injection time, standard-concentration contrast media (iohexol 350 mgI/mL)","comparator":"Standard-Dose (SD) protocol: 100 kVp, ASIR-V 50% reconstruction, iodine load of 245 mgI/kg, 10-second injection time, iohexol 350 mgI/mL","primaryOutcome":"Quantitative image quality (vascular attenuation, image noise, SNR, CNR) and qualitative image quality; diagnostic performance also assessed (specific primary endpoint hierarchy and statistical thresholds not reported in the provided abstract excerpt)","followUp":"Not reported (cross-sectional imaging study; no longitudinal follow-up described)","fundingSource":"Not reported"}
Key findings
Based on the truncated abstract provided, the Triple-Low (TL) group achieved the following reductions compared to the Standard-Dose (SD) group: radiation dose reduced by 29.4%, contrast media (CM) volume reduced by 47.5%, and CM injection rate reduced by 23.5%. Corresponding reductions for the Quadruple-Low (QL) group, qualitative and quantitative image quality metrics (SNR, CNR, image noise, vascular attenuation values), diagnostic performance data (sensitivity, specificity, AUC, or agreement statistics), and all confidence intervals and p-values were not reported in the abstract excerpt provided. No adverse event or contrast reaction data were reported in the available text. No NNT or NNH is calculable from the data provided.
Practice implications
The study addresses a clinically relevant challenge: high-BMI patients typically require higher radiation and contrast loads for adequate CCTA image quality, yet they also carry elevated baseline risk for contrast-induced nephropathy and radiation-related harm. The TL arm data confirm that meaningful dose reductions (≈30% radiation, ≈47% CM volume) are achievable at 80 kVp with DLIR-H in this population. Whether the QL protocol (substituting iodixanol 320 mgI/mL for iohexol 350 mgI/mL, representing a further reduction in iodine concentration) maintains equivalent image quality and diagnostic accuracy compared to both TL and SD groups cannot be confirmed from the truncated abstract. Patients studied are overweight to obese (BMI ≥ 25 kg/m²), a population frequently underrepresented in prior low-dose CCTA trials that typically focused on normal or mildly overweight patients. The study does not address clinical outcomes (MACE, revascularization rates) or the impact of these protocols on downstream diagnostic decision-making. IMPORTANT LIMITATION: Only an abstract—and a truncated one—was available for review. Key quantitative results, statistical significance thresholds, image quality scores, and diagnostic performance metrics for the QL group are absent from the provided text. Definitive conclusions about the QL protocol's performance relative to SD or TL cannot be drawn. __LIMITATIONS__ Abstract truncated: critical quantitative results for the QL group, p-values, confidence intervals, and diagnostic performance metrics are not available for review.,Relatively small sample size (n=180 across three arms), limiting statistical power for subgroup analyses and diagnostic performance estimation.,Single-center design (implied): generalizability to different CT platforms, technologist practices, and patient populations is uncertain.,BMI ≥ 25 kg/m² is a broad inclusion criterion encompassing both overweight and severely obese patients; results may not be uniform across this BMI range.,No reference standard (invasive coronary angiography) explicitly described for diagnostic performance validation in the available text.,Radiation dose and contrast reduction are surrogate endpoints; no clinical outcome data (nephropathy rates, major adverse cardiac events) reported.,Funding source not reported; potential conflicts of interest unknown.,Iodixanol (iso-osmolar) vs. iohexol (low-osmolar) represents both a concentration and formulation difference, making it difficult to isolate the contribution of each variable to the QL protocol's performance.,Blinding of image quality assessors not confirmed in the available abstract text. __BOTTOM_LINE_CATEGORY__ promising_but_preliminary __BOTTOM_LINE__ A quadruple-low CCTA protocol combining 80 kVp, DLIR-H reconstruction, reduced iodine load (128 mgI/kg), and low-concentration iso-osmolar contrast (iodixanol 320 mgI/mL) appears feasible in high-BMI patients, with the triple-low arm demonstrating approximately 29% radiation and 47% contrast volume reductions versus a standard-dose protocol. However, the truncated abstract does not permit full evaluation of image quality metrics or diagnostic accuracy for the quadruple-low arm, and no clinical outcome data are reported. This study is hypothesis-generating and should be considered preliminary; it is not sufficient alone to justify changing institutional CCTA protocols in overweight or obese patients pending full publication and independent replication.