Browsing by Author "Meyer, Mathias"
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Item Comparison of Iodine Quantification and Conventional Attenuation Measurements for Differentiating Small, Truly Enhancing Renal Masses From High-Attenuation Nonenhancing Renal Lesions With Dual-Energy CT(2019) Meyer, Mathias; Nelson, Rendon; Vernuccio, Federica; González, Fernando; Schabel, Christoph; Mileto, Achille; Patel, Bhavik; Schoenberg, Stefan; Marin, DanieleOBJECTIVE. The purpose of this study is to determine whether iodine quantification techniques from contrast-enhanced dual-energy CT (DECT) data allow equal differentiation of small enhancing renal masses from high-attenuation (> 20 HU of unenhanced attenuation) nonenhancing lesions, compared with conventional attenuation measurements. MATERIALS AND METHODS. A total of 220 nonconsecutive patients (mean [± SD] age, 66 ± 13 years; 130 men and 90 women) with 265 high-attenuation renal lesions (mean attenuation, 54 ± 33 HU; 91 enhancing lesions) were included. Each patient underwent single-energy unenhanced CT followed by DECT during the nephrographic phase using one of four different high-end DECT platforms (first- and second-generation rapid-kilovoltage-switching DECT platforms and second- and third-generation dual-source DECT platforms). Iodine quantification measurements and conventional attenuation change measurements were calculated for each lesion. Diagnostic accuracy was determined by pathologic analysis, confirmation with another imaging modality, or greater than 24 months of imaging follow-up as the reference standard. RESULTS. The diagnostic accuracy for differentiating enhancing from nonenhancing renal lesions was significantly higher for conventional attenuation change measurements, compared with iodine quantification measurements (AUC values, 0.973 vs 0.875; p < 0.0001). The diagnostic performance of iodine quantification measurements improved only marginally with the utilization of DECT platform-specific optimized iodine quantification thresholds, yielding AUC values of 0.907 and 0.893 for the rapid-kilovoltage-switching DECT and dual-source DECT platforms, respectively. Unenhanced lesion attenuation (p = 0.0010) and intraparenchymal location (p = 0.0249) significantly influenced the diagnostic accuracy of the iodine quantification techniques. CONCLUSION. Iodine quantification from DECT data yields inferior diagnostic accuracy when compared with conventional attenuation change measurements for differentiating small, truly enhancing renal masses and high-attenuation renalItem LI-RADS: Diagnostic Performance of Hepatobiliary Phase Hypointensity and Major Imaging Features of LR-3 and LR-4 Lesions Measuring 10-19 mm With Arterial Phase Hyperenhancement(2019) Vernuccio, Federica; Cannella, Roberto; Meyer, Mathias; Choudhoury, Kingshuk Roy; González, Fernando; Schwartz, Fides R.; Gupta, Rajan T.; Bashir, Mustafa R.; Furlan, Alessandro; Marin, DanieleOBJECTIVE. The purpose of this study was to determine the diagnostic performance of hepatobiliary phase hypointensity and Liver Imaging Reporting and Data System (LI-RADS) major imaging features in the diagnosis of hepatocellular carcinoma (HCC) in hepatic lesions with arterial phase hyperenhancement (APHE) measuring 10-19 mm in patients at high risk of HCC. MATERIALS AND METHODS. A composite reference standard of pathologic analysis and imaging follow-up was used. The diagnostic performance (sensitivity and specificity) of hepatobiliary phase hypointensity and LI-RADS major imaging features other than APHE for the diagnosis of HCC was assessed and compared by means of a logistic regression model. RESULTS. This retrospective dual-institution study included 189 LI-RADS LR-3 and LR-4 lesions measuring 10-19 mm and having APHE in 144 consecutively registered patients (96 men, 48 women; mean age, 58 years). Hepatobiliary phase hypointensity had significantly higher sensitivity (84% [92/109], p < 0.00001) than major imaging features in the diagnosis of HCC but lower specificity (84% [67/80]; p = 0.01). However, hepatobiliary phase hypointensity in LR-3 observations measuring 10-19 mm and having APHE had moderately elevated sensitivity (73% [44/60]) and specificity (85%, 64/75). All three major imaging features had high specificity for the diagnosis of HCC, including 95% (76/80) for washout, 100% (80/80) for enhancing capsule, and 99% (79/80) for threshold growth. CONCLUSION. Major imaging features have high specificity for the diagnosis of HCC in lesions measuring 10-19 mm that have APHE. The finding of hepatobiliary phase hypointensity significantly improves sensitivity while moderately high specificity is maintained for the diagnosis of HCC in LR-3 lesions measuring 10-19 mm that exhibit APHE.Item Variability of quantitative measurements of metastatic liver lesions: a multi‑radiation‑dose‑level and multi‑reader comparison(2020) Ding, Yuqin; Marin, Daniele; Vernuccio, Federica; Gonzalez, Fernando; Williamson, Hannah V.; Becker, Hans‑Christoph; Patel, Bhavik N.; Solomon, Justin; Ramirez‑Giraldo, Juan Carlos; Samei, Ehsan; Nelson, Rendon C.; Meyer, MathiasPurpose To evaluate the variability of quantitative measurements of metastatic liver lesions by using a multi-radiation-doselevel and multi-reader comparison. Methods Twenty-three study subjects (mean age, 60 years) with 39 liver lesions who underwent a single-energy dual-source contrast-enhanced staging CT between June 2015 and December 2015 were included. CT data were reconstructed with seven different radiation dose levels (ranging from 25 to 100%) on the basis of a single CT acquisition. Four radiologists independently performed manual tumor measurements and two radiologists performed semi-automated tumor measurements. Interobserver, intraobserver, and interdose sources of variability for longest diameter and volumetric measurements were estimated and compared using Wilcoxon rank-sum tests and intraclass correlation coefficients. Results Inter- and intraobserver variabilities for manual measurements of the longest diameter were higher compared to semi-automated measurements (p < 0.001 for overall). Inter- and intraobserver variabilities of volume measurements were higher compared to the longest diameter measurement (p < 0.001 for overall). Quantitative measurements were statistically different at < 50% radiation dose levels for semi-automated measurements of the longest diameter, and at 25% radiation dose level for volumetric measurements. The variability related to radiation dose was not significantly different from the inter- and intraobserver variability for the measurements of the longest diameter. Conclusion The variability related to radiation dose is comparable to the inter- and intraobserver variability for measurements of the longest diameter. Caution should be warranted in reducing radiation dose level below 50% of a conventional CT protocol due to the potentially detrimental impact on the assessment of lesion response in the liver.Item Virtual Unenhanced Images at Dual-Energy CT: Influence on Renal Lesion Characterization(RSNA, 2019-05) Meyer, Mathias; Nelson, Rendon; Vernuccio, Federica; González, Fernando; Farjat, Alfredo; Patel, Bhavik; Samei, Ehsan; Henzler, Thomas; Schoenberg, Stefan; Marin, DanieleBackground Dual-energy (DE) CT allows reconstruction of virtual noncontrast (VNC) images from a single-phase contrast agent-enhanced examination, potentially reducing the need for multiphasic CT to characterize renal lesions. However, data regarding diagnostic performance of VNC images for the characterization of renal lesions are limited. Purpose To determine whether renal mass CT performed by using VNC images allows for reliable identification of renal lesions and differentiation of contrast-enhanced from unenhanced lesions, compared with unenhanced images. Materials and Methods This is a retrospective study of 293 patients (105 women [mean age, 65 years; age range, 18-91 years] and 188 men [mean age, 66 years; age range, 23-90 years] with 379 renal lesions [craniocaudal diameter, 1.0-4.0 cm]) who underwent a single-energy unenhanced CT examination followed by a nephrographic-phase DE CT between June 2013 and October 2017 by using one of four different DE CT platforms from two vendors. VNC images were calculated by using vendor-specific algorithms. Each lesion was classified in a blinded and independent fashion by using the VNC or unenhanced image in combination with the nephrographic images. Attenuation measurements were obtained on the VNC, unenhanced, and nephrographic images. Unenhanced images and pathologic or imaging follow-up for more than 24 months served as reference standard. Results There was strong overall agreement between VNC and unenhanced images for renal lesion characterization (Cramer V = 0.85). VNC images yielded a high diagnostic performance (area under the receiver operating characteristic curve, 0.91; 95% confidence interval: 0.86, 0.95) for facilitation of differentiation of contrast-enhanced from unenhanced renal lesions. However, there was a reduction in diagnostic performance for depicting contrast-enhanced renal lesions by using VNC compared with unenhanced images (area under the receiver operating characteristic curve, 0.91 [95% confidence interval: 0.86, 0.95] vs 0.96 [95% confidence interval: 0.93, 0.99]; P < .001). Mean absolute difference between the VNC and unenhanced attenuation was 9.2 HU ± 8.7. Conclusion Virtual noncontrast images enabled accurate renal lesion characterization, albeit with a reduction in diagnostic performance for contrast-enhanced lesion characterization.