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Objective Reproducibility problems are a known limitation of radiomics. The segmentation of the target lesion plays a critical role in texture analysis variability. This study’s aim was to compare the interobserver reliability of manual 2D vs. 3D lung lesion segmentation with and without pre-definition of the volume using a threshold of − 50 HU. Methods Seventy-five patients with histopathologically proven lung lesions (15 patients each with adenocarcinoma, squamous cell carcinoma, small cell lung cancer, carcinoid, and organizing pneumonia) who underwent an unenhanced CT scan of the chest were included. Three radiologists independently segmented each lesion manually in 3D and 2D with and without pre-segmentation volume definition by a HU threshold, and shape parameters and original, Laplacian of Gaussian–filtered, and wavelet-based texture features were derived. To assess interobserver reliability and identify the most robust texture features, intraclass correlation coefficients (ICCs) for different segmentation settings were calculated. Results Shape parameters had high reliability (64–79% had excellent and good ICCs). Texture features had weak reliability levels, with the highest ICCs (38% excellent or good) found for original features in 3D segmentation without the use of a HU threshold. A small proportion (4.3–11.5%) of texture features had excellent or good ICC values at all segmentation settings. Conclusion Interobserver reliability of texture features from CT scans of a heterogeneous collection of manually segmented lung lesions was low with a small proportion of features demonstrating high reliability independent of the segmentation settings. These results indicate a limited applicability of texture analysis and the need to define robust texture features in patients with lung lesions. Key Points • Our study showed a low reproducibility of texture features when 3 radiologists independently segmented lung lesions in CT images, which highlights a serious limitation of texture analysis. • Interobserver reliability of texture features was low regardless of whether the lesion was segmented in 2D and 3D with or without a HU threshold. • In contrast to texture features, shape parameters showed a high interobserver reliability when lesions were segmented in 2D vs. 3D with and without a HU threshold of − 50.

Purpose To evaluate the utility of non-contrast-enhanced CT texture analysis (CTTA) for predicting the histopathological differentiation of pancreatic ductal adenocarcinomas (PDAC) and to compare non-contrast-enhanced CTTA texture features between primary PDAC and hepatic metastases of PDAC. Methods This retrospective study included 120 patients with histopathologically confirmed PDAC. Sixty-five patients underwent CT-guided biopsy of primary PDAC, while 55 patients underwent CT-guided biopsy of hepatic PDAC metastasis. All lesions were segmented in non-contrast-enhanced CT scans for CTTA based on histogram analysis, co-occurrence matrix, and run-length matrix. Statistical analysis was conducted for 372 texture features using Mann–Whitney U test, Bonferroni–Holm correction, and receiver operating characteristic (ROC) analysis. A p value Results Three features were identified that differed significantly between histopathological G2 and G3 primary tumors. Of these, “low gray-level zone emphasis” yielded the largest AUC (0.87 ± 0.04), reaching a sensitivity and specificity of 0.76 and 0.83, respectively, when a cut-off value of 0.482 was applied. Fifty-four features differed significantly between primary and hepatic metastatic PDAC. Conclusion Non-contrast-enhanced CTTA of PDAC identified differences in texture features between primary G2 and G3 tumors that could be used for non-invasive tumor assessment. Extensive differences between the features of primary and metastatic PDAC on CTTA suggest differences in tumor microenvironment. Graphical Abstract

Computed tomography pulmonary angiography (CT-PA) is frequently used in the diagnostic workup of pulmonary embolism (PE), even in highly radiosensitive patient populations. This study aims to assess CT-PA with reduced z -axis coverage (compared with a standard scan range covering the entire lung) for its sensitivity for detecting PE and its potential to reduce the radiation dose.We retrospectively analyzed 602 consecutive CT-PA scans with definite or possible PE reported. A reduced scan range was defined based on the topogram, where the cranial slice was set at the top of the aortic arch and the caudal slice at the top of the lower hemidiaphragm. Locations of emboli in relation to the reduced scan range were recorded.We included 513 CT-PA scans with definite acute PE in statistical analysis. Patients' median age was 66 (52 to 77) years, 46% were female. Median dose length product was 270.8 (111.3 to 503.9) mGy*cm. Comparing the original and reduced scan ranges, the mean scan length was significantly reduced by 48.0±8.6% (26.8±3.0 vs. 13.9±2.6 cm, P0.001). Single emboli outside the reduced range in addition to emboli within were found in 15 scans (2.9%), while only 1 scan (0.2%) had an embolus outside the reduced range and none within it. The resulting sensitivity of CT-PA with reduced scan range was 99.81% (95% confidence interval: 98.74%-99.99%) for detecting any PE.A reduced scan length in CT-PA, as defined above, would substantially decrease radiation dose while maintaining diagnostic accuracy for detecting PE.

Comparison of puncture deviation and puncture duration between computed tomography (CT)- and C-arm CT (CACT)-guided puncture performed by residents in training (RiT).In a cohort of 25 RiTs enrolled in a research training program either CT- or CACT-guided puncture was performed on a phantom. Prior to the experiments, the RiT's level of training, experience playing a musical instrument, video games, and ball sports, and self-assessed manual skills and spatial skills were recorded. Each RiT performed two punctures. The first puncture was performed with a transaxial or single angulated needle path and the second with a single or double angulated needle path. Puncture deviation and puncture duration were compared between the procedures and were correlated with the self-assessments.RiTs in both the CT guidance and CACT guidance groups did not differ with respect to radiologic experience (p = 1), angiographic experience (p = 0.415), and number of ultrasound-guided puncture procedures (p = 0.483), CT-guided puncture procedures (p = 0.934), and CACT-guided puncture procedures (p = 0.466). The puncture duration was significantly longer with CT guidance (without navigation tool) than with CACT guidance with navigation software (p 0.001). There was no significant difference in the puncture duration between the first and second puncture using CT guidance (p = 0.719). However, in the case of CACT, the second puncture was significantly faster (p = 0.006). Puncture deviations were not different between CT-guided and CACT-guided puncture (p = 0.337) and between the first and second puncture of CT-guided and CACT-guided puncture (CT: p = 0.130; CACT: p = 0.391). The self-assessment of manual skills did not correlate with puncture deviation (p = 0.059) and puncture duration (p = 0.158). The self-assessed spatial skills correlated positively with puncture deviation (p = 0.011) but not with puncture duration (p = 0.541).The RiTs achieved a puncture deviation that was clinically adequate with respect to their level of training and did not differ between CT-guided and CACT-guided puncture. The puncture duration was shorter when using CACT. CACT guidance with navigation software support has a potentially steeper learning curve. Spatial skills might accelerate the learning of image-guided puncture.· The CT-guided and CACT-guided puncture experience of the RiTs selected as part of the program "Researchers for the Future" of the German Roentgen Society was adequate with respect to the level of training.. · Despite the lower collective experience of the RiTs with CACT-guided puncture with navigation software assistance, the learning curve regarding CACT-guided puncture may be faster compared to the CT-guided puncture technique.. · If the needle path is complex, CACT guidance with navigation software assistance might have an advantage over CT guidance..· Meine TC, Hinrichs JB, Werncke T et al. Phantom study for comparison between computed tomography- and C-Arm computed tomography-guided puncture applied by residents in radiology. Fortschr Röntgenstr 2022; 194: 272 - 280.ZIEL: Vergleich der Punktionsabweichung und -dauer zwischen Computertomografie (CT) – und C-Arm-CT (CACT) -gesteuertem Punktionsverfahren bei Anwendung durch Assistenzärzte in Weiterbildung (AiW).In einer Kohorte von 25 AiW, die Teil einer wissenschaftlichen Förderung waren, wurden entweder CT- oder CACT-gesteuerte Punktionen an einem Phantom durchgeführt. Vor Beginn wurden der Weiterbildungsstand, die Erfahrung mit Spielen eines Musikinstruments, mit Videospielen und mit Ballsportarten und die Selbsteinschätzung von manueller Geschicklichkeit und räumlichem Denkvermögen abgefragt. Jede/r AiW führte 2 Punktionen durch, wobei die 1. Punktion mit einem transaxialen bzw. einfach angulierten Nadelpfad und die 2. Punktion mit einem einfach bzw. doppelt angulierten Nadelpfad erfolgte. Punktionsabweichung und -dauer wurden zwischen den Verfahren verglichen und mit den Selbsteinschätzungen korreliert.Die beiden Gruppen der AiW zeigten keine Unterschiede in der Erfahrung in der Radiologie (p = 1), in der Angiografie (p = 0.415) und in der Anzahl bereits durchgeführter Punktionen gesteuert durch Ultraschall (p = 0,483), CT (p = 0,934) und CACT (p = 0,466). In der CT (ohne Navigationssoftware) war die Punktionsdauer signifikant länger als mit der CACT-Bildsteuerung mit Navigationssoftware (p 0,001). Bei der Punktionsdauer zeigten sich keine signifikanten Unterschiede zwischen der 1. und 2. Punktion im CT (p = 0,719), während die 2. Punktion mit CACT schneller durchgeführt werden konnte (p = 0,006). Die Punktionsabweichung war weder signifikant zwischen CT- und CACT-Bildsteuerung (p = 0,337), noch zwischen der 1. und 2. Punktion der jeweiligen Verfahren (CT: p = 0,130; CACT: p = 0,391). Die Selbsteinschätzung der manuellen Geschicklichkeit korrelierte nicht mit der Punktionsabweichung (p = 0,059) und -dauer (p = 0,158). Das subjektive räumliche Denkvermögen zeigte eine moderate positive Korrelation zur Punktionsabweichung (p = 0,011), aber nicht zur -dauer (p = 0,541).Die AiW erreichten eine dem Ausbildungsstand entsprechende, klinisch adäquate Punktionsabweichung unter CT- und CACT-Bildsteuerung. Die CACT-gesteuerten Punktionen mit Unterstützung durch Navigationssoftware wurden schneller durchgeführt, und auch die Lernkurve war mit CACT-Bildsteuerung steiler. Räumliches Denkvermögen kann möglicherweise das Erlernen bildgesteuerter Punktionen beschleunigen.· Die Erfahrung mit Punktionen war in einer Gruppe von AiW, die im Rahmen des Programms der Deutschen Röntgengesellschaft e. V. „Forscher-für-die-Zukunft“ ausgesucht wurden, dem Weiterbildungsstand entsprechend.. · Trotz kollektiv geringerer Erfahrung der radiologischen AiW mit der CACT-gesteuerten Punktion mit Navigationssoftwareunterstützung ist die Lernkurve gegenüber der einfachen CT-Punktion möglicherweise steiler.. · Bei schwierigen Punktionswegen könnte die CACT-Bildsteuerung mit Softwareunterstützung einen Vorteil in der Durchführung gegenüber der konventionellen CT-Bildsteuerung haben..· Meine TC, Hinrichs JB, Werncke T et al. Phantom study for comparison between computed tomography- and C-Arm computed tomography-guided puncture applied by residents in radiology. Fortschr Röntgenstr 2022; 194: 272 – 280.

Purpose To assess correlations of lean body weight (LBW) calculated with various formulas, total body weight (TBW), body height (BH), body mass index (BMI), body surface area (BSA) and fat-free mass (FFM) with vascular and parenchymal enhancement in multiphasic CT of the liver. Method Thirty consecutive patients underwent multiphasic CT of the liver using constant iodine dose and flow rate. Contrast enhancement of aorta, portal vein and liver was calculated by measuring mean vascular and parenchymal attenuation in pre-contrast and post-contrast phases. Correlations of TBW, BH, BMI, BSA, FFM, and LBW (calculated with formulas of Boer, Hume, James and Green&Duffull) with enhancement were tested using Spearman’s correlation coefficient. The method of Fieller et al. was used to calculate 95 % confidence intervals. A p-value ≤ 0.05 was considered statistically significant. Results Aortal enhancement correlated strongly with TBW, BSA, LBWBoer and LBWHume and moderately with BH, BMI, FFM, LBWJames and LBWGreen&Duffull. Liver enhancement in the late arterial phase correlated moderately with TBW, FFM, LBWBoer, LBWHume and LBWGreen&Duffull and weakly with BSA. Liver enhancement in the portal venous phase correlated strongly with TBW, BSA, FFM, LBWBoer, LBWHume and LBWGreen&Duffull, whereby overlap of the 95 % CI graphs demonstrated that the differences in the correlation coefficients were not statistically significant. Liver enhancement in the delayed phase correlated moderately with BH but did not correlate significantly with any other parameter. Conclusion Regardless of the form used for calculation, LBW did not correlate statistically significantly stronger than TBW with vascular or parenchymal enhancement of the liver.