Diagnostic performance of dual-energy CT and subtraction CT for renal lesion detection and characterization
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To compare the effect of dual-energy CT (DECT) material density datasets on diagnostic performance, readers’ confidence, and interpretation time for renal lesion detection and characterization in comparison to subtraction CT (SCT).
Material and methods
One hundred fourteen patients (69/45 = M/F, mean age = 67 years) who underwent contrast-enhanced DECT between January 2015 and February 2018 for suspected renal mass were included retrospectively. For each patient, three radiologists assessed three image datasets: group A, material density iodine (MDI) + material density water (MDW); group B, SCT only; and group C, SCT + true unenhanced phase + virtual monochromatic images at 65 keV. Readers evaluated image quality (4-point scale), the number of lesions, and likely diagnosis. Reading times were recorded. Quantitatively, iodine concentration (IC from MDI) and delta Hounsfield units (ΔHU) for all lesions were measured. Diagnostic accuracy was compared using the area under the receiver operating characteristic curve (AUC). Image quality and interpretation time were compared with Kruskal-Wallis and t tests.
Study cohort (230 lesions; mean size = 23.63 mm (5–116 mm)) consisted of 60 enhancing, 158 non-enhancing, and 12 lipid-dominant angiomyolipoma lesions. Significantly higher image quality was demonstrated for MDI compared to SCT (mean score = 3.82 vs. 3; p < 0.05). Comparable diagnostic accuracy was observed for group A (AUC = 0.88) and group C (AUC = 0.87) and was higher compared to that for group B (AUC = 0.75). Group A was read faster than group C (41.49 s vs. 71.45 s per exam; p < 0.05). Both IC and ΔHU values had high accuracy (AUC = 0.97) for differentiating enhancing vs. non-enhancing lesions; however, IC enabled differentiation of clear cell renal cell carcinoma from other enhancing lesions with moderate accuracy (AUC = 0.73).
MDI images increase readers’ confidence for renal lesion detection and characterization while providing a more efficient radiologist workflow, irrespective of readers’ experience.
• Material density iodine (MDI) images enable faster interpretation due to high image quality and potentially reduced need for quantitation.
• MDI images increase diagnostic confidence of readers, irrespective of radiologists’ experience.
• High accuracy with dual-energy CT (DECT) can potentially reduce healthcare costs by eliminating the need for additional investigations.
KeywordsKidney X-ray computed tomography Workflow Neoplasms Radiologist
Area under the receiver operating characteristic curve
Clear cell renal cell carcinoma
Dual-source dual-energy CT
Material density iodine
Material density water
Normalized iodine concentration
Multiphasic renal mass protocol with conventional CT
Receiver operating characteristic
Region of interest
Rapid kV-switching dual-energy CT
Picture archiving and communication system
Renal cell carcinoma
Stimulated single-energy CT
This work was conducted with support from the Harvard Catalyst | The Harvard Clinical and Translational Science Center (National Center for Advancing Translational Sciences, National Institutes of Health Award UL 1TR002541) and financial contributions from Harvard University and its affiliated academic healthcare centers. The content is solely the responsibility of the authors and does not necessarily represent the official views of Harvard Catalyst, Harvard University, and its affiliated academic healthcare centers, or the National Institutes of Health.
The authors state that this work has not received any funding.
Compliance with ethical standards
The scientific guarantor of this publication is Dushyant Vasudeo Sahani.
Conflict of interest
Dushyant Vasudeo Sahani, MD has the following disclosures which are not relevant to this work: research grant support from GE, Philips, and Bayer Healthcare; royalties (Elsevier); and being a consultant of Allena Pharmaceuticals, GE Healthcare. Other authors have no relevant disclosure. The data was handled by an investigator with no conflict of interest.
Statistics and biometry
Hang Lee, Ph.D. kindly provided the statistical advice for this manuscript. One of the authors has significant statistical expertise.
Written informed consent was waived by the institutional review board.
Institutional review board approval was obtained.
• diagnostic study
• performed in one institution
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