Diagnostic performance of photon-counting detector CT for differentiation between adrenal adenomas and metastases.

OBJECTIVES: Aim of this study was to assess the value of virtual non-contrast (VNC) reconstructions in differentiating between adrenal adenomas and metastases on a photon-counting detector CT (PCD-CT). MATERIAL AND METHODS: Patients with adrenal masses and contrast-enhanced CT scans in portal venous phase were included. Image reconstructions were performed, including conventional VNC (VNCConv) and PureCalcium VNC (VNCPC), as well as virtual monochromatic images (VMI, 40-90 keV) and iodine maps. We analyzed images using semi-automatic segmentation of adrenal lesions and extracted quantitative data. Logistic regression models, non-parametric tests, Bland-Altman plots, and a random forest classifier were used for statistical analyses. RESULTS: The final study cohort consisted of 90 patients (36 female, mean age 67.8 years [range 39-87]) with adrenal lesions (45 adenomas, 45 metastases). Compared to metastases, adrenal adenomas showed significantly lower CT-values in VNCConv and VNCPC (p = 0.007). Mean difference between VNC and true non-contrast (TNC) was 17.67 for VNCConv and 14.85 for VNCPC. Random forest classifier and logistic regression models both identified VNCConv and VNCPC as the best discriminators. When using 26 HU as the threshold in VNCConv reconstructions, adenomas could be discriminated from metastases with a sensitivity of 86.7% and a specificity of 75.6%. CONCLUSION: VNC algorithms overestimate CT values compared to TNC in the assessment of adrenal lesions. However, they allow a reliable discrimination between adrenal adenomas and metastases and could be used in clinical routine in near future with an increased threshold (e.g., 26 HU). Further (multi-center) studies with larger patient cohorts and standardized protocols are required. CLINICAL RELEVANCE STATEMENT: VNC reconstructions overestimate CT values compared to TNC. Using a different threshold (e.g., 26 HU compared to the established 10 HU), VNC has a high diagnostic accuracy for the discrimination between adrenal adenomas and metastases. KEY POINTS: • Virtual non-contrast reconstructions may be promising tools to differentiate adrenal lesions and might save further diagnostic tests. • The conventional and a new calcium-preserving virtual non-contrast algorithm tend to systematically overestimate CT-values compared to true non-contrast images. • Therefore, increasing the established threshold for true non-contrast images (e.g., 10HU) may help to differentiate between adrenal adenomas and metastases on contrast-enhanced CT.

Inpatient treatment of acute diverticulitis between 2010 and 2021 - A German nationwide study about long-term trends and effects of the SARS-CoV-2 pandemic.

AIM: The aims of this study were to analyse all hospitalizations for acute diverticulitis in Germany from 2010 to 2021 and to assess the effects of the first 2 years of the SARS-CoV-2 pandemic on hospitalizations for acute diverticulitis. METHOD: Using data from the German Federal Statistical Office, we analysed fully anonymized healthcare data of hospitalizations and treatment regimens with acute diverticulitis as the main diagnosis between 2010 and 2021. Logistic regression analyses for in-hospital mortality were performed. RESULTS: A total of 608,162 hospitalizations were included. While the number of hospitalizations constantly increased until 2019 (+52.4%), a relative decrease of 10.1% was observed between 2019 and 2020, followed by stable numbers of hospitalizations in 2021 (+1.1% compared with 2020). In-hospital mortality showed a relative decrease of 33.2% until 2019 and thereafter a relative increase of 26.9% in 2020 and of 7.5% in 2021. A 21.6% and a 19.3% drop in hospitalizations was observed during the first and second waves of the SARS-CoV-2 pandemic, mostly affecting hospitalizations for uncomplicated diverticulitis, with a corresponding 11.6% and 16.8% increase in admissions for complicated diverticulitis. Multivariable logistic regression analyses showed significantly higher in-hospital mortality for hospitalizations in which surgery (OR = 2.76) and CT (OR = 1.32) were given, as well as lower mortality for women (OR = 0.88), whereas percutaneous drainage was not associated with higher in-hospital mortality compared with conservative treatment (OR = 0.71). CONCLUSION: This study points out the long-term trends in inpatient treatment for acute diverticulitis and the in-hospital mortality risk factors of patients hospitalized for acute diverticulitis in a large nationwide cohort, as well as changes in these trends and factors resulting from the SARS-CoV-2 pandemic. These changes might be attributable to delayed diagnosis and thus more severe stages of disease as a result of containment measures.

Heart rate sensitivity of virtual non-contrast calcium scores derived from photon counting detector CT data: a phantom study.

PURPOSE: To assess the reliability of virtual non-contrast (VNC) derived coronary artery calcium quantities in relation to heart rate and the VNC algorithm used compared to reference true non-contrast (TNC), considering several clinically established acquisition modes. MATERIAL AND METHODS: An ad hoc built coronary phantom containing four calcified lesions and an iodinated lumen was scanned using three cardiac acquisition modes three times within an anthropomorphic cardiac motion phantom simulating different heart rates (0, 60, 80, 100 bpm) and reconstructed with a conventional (VNCconv) and a calcium-sensitive (VNCpc) VNC algorithm. TNC reference was scanned at 0 bpm with non-iodinated lumen. Calcium scores were assessed in terms of number of lesions detected, Agatston and volume scores and global noise was measured. Paired t-test and Wilcoxon test were performed to test measurements for significant difference. RESULTS: For both VNC algorithms used, calcium levels or noise were not significantly affected by heart rate. Measurements on VNCpc reconstructions best reproduced TNC results, but with increased variability (Agatston scores at 0 bpm for TNC, VNCconv, and VNCpc were 47.1 ± 1.1, 6.7 ± 2.8 (p < 0.001), and 45.3 ± 7.6 (p > 0.05), respectively). VNC reconstructions showed lower noise levels compared to TNC, especially for VNCpc (noiseheart on TNC, VNCconv and VNCpc at 0 bpm was 5.0 ± 0.4, 4.5 ± 0.2, 4.2 ± 0.2). CONCLUSION: No significant heart rate dependence of VNC-based calcium scores was observed in an intra-reconstruction comparison. VNCpc reproduces TNC scores better than VNCconv without significant differences and decreased noise, however, with an increasing average deviation with rising heart rates. VNC-based CACS should be used with caution as the measures show higher variability compared to reference TNC and therefore hold the potential of incorrect risk categorization.

Assessment of epicardial adipose tissue on virtual non-contrast images derived from photon-counting detector coronary CTA datasets.

OBJECTIVES: To assess epicardial adipose tissue (EAT) volume and attenuation of different virtual non-contrast (VNC) reconstructions derived from coronary CTA (CCTA) datasets of a photon-counting detector (PCD) CT-system to replace true non-contrast (TNC) series. METHODS: Consecutive patients (n = 42) with clinically indicated CCTA and coronary TNC were included. Two VNC series were reconstructed, using a conventional (VNCConv) and a novel calcium-preserving (VNCPC) algorithm. EAT was segmented on TNC, VNCConv, VNCPC, and CCTA (CTA-30) series using thresholds of -190 to -30 HU and an additional segmentation on the CCTA series with an upper threshold of 0 HU (CTA0). EAT volumes and their histograms were assessed for each series. Linear regression was used to correlate EAT volumes and the Euclidian distance for histograms. The paired t-test and the Wilcoxon signed-rank test were used to assess differences for parametric and non-parametric data. RESULTS: EAT volumes from VNC and CCTA series showed significant differences compared to TNC (all p < .05), but excellent correlation (all R2 > 0.9). Measurements on the novel VNCPC series showed the best correlation (R2 = 0.99) and only minor absolute differences compared to TNC values. Mean volume differences were -12%, -3%, -13%, and +10% for VNCConv, VNCPC, CTA-30, and CTA0 compared to TNC. Distribution of CT values on VNCPC showed less difference to TNC than on VNCConv (mean attenuation difference +7% vs. +2%; Euclidean distance of histograms 0.029 vs. 0.016). CONCLUSIONS: VNCPC-reconstructions of PCD-CCTA datasets can be used to reliably assess EAT volume with a high accuracy and only minor differences in CT values compared to TNC. Substitution of TNC would significantly decrease patient's radiation dose. KEY POINTS: • Measurement of epicardial adipose tissue (EAT) volume and attenuation are feasible on virtual non-contrast (VNC) series with excellent correlation to true non-contrast series (all R2>0.9). • Differences in VNC algorithms have a significant impact on EAT volume and CT attenuation values. • A novel VNC algorithm (VNCPC) enables reliable assessment of EAT volume and attenuation with superior accuracy compared to measurements on conventional VNC- and CCTA-series.

Treatment of acute mesenteric ischemia between 2010 and 2020 - a German nation-wide study.

BACKGROUND: Aim of this study was to analyze long-term trends of hospitalizations, treatment regimen and in-hospital mortality of in-patients with acute mesenteric ischemia (AMI) over the past decade and effects of the SARS-CoV2-pandemic. METHODS: We analyzed fully anonymized data from the German Federal Statistical Office of patients with AMI between 2010 and 2020. Besides descriptive analyses of age, gender, in-hospital mortality, comorbidity burden and treatment regimen, multivariable logistic regression analyses were performed to identify independent variables associated with in-hospital mortality and different treatment. RESULTS: A total of 278,121 hospitalizations (120,667 male [43.4%], mean age 72.1 years) with AMI were included in this study. The total number of hospitalizations increased from 2010 (n = 24,172) to 2019 (n = 26,684) (relative increase 10.4%). In-hospital mortality decreased over the past decade from 36.6% to 2010 to 31.1% in 2019 (rel. decrease 15.2%). Independent risk factors for in-hospital mortality were older age (OR = 1.03 per year), higher comorbidity burden (OR = 1.06 per point in van Walraven score [vWs]), male gender (OR = 1.07), AMI as a secondary diagnosis (OR = 1.44), and the need for surgical (visceral surgery: OR = 1.38, vascular surgery: OR = 3.33) and endovascular treatment (OR = 1.21). We report a decline in hospitalizations during the first wave of infection in spring 2020 (rel. decrease 9.7%). CONCLUSION: In-hospital mortality rate has declined over the past decade, but remains high at above 30%. Older age, increased comorbidity and male gender are independent factors for in-hospital mortality. Hospitalizations requiring vascular surgery are associated with high in-hospital mortality, followed by visceral surgery and endovascular approaches. The first wave of the SARS-CoV2-pandemic in spring 2020 implied a decrease in hospital admissions.

Anemia Detection by Hemoglobin Quantification on Contrast-enhanced Photon-counting CT Data Sets.

See also the editorial by Dodd and MacDermott in this issue.

In-patient care trends in peripheral artery disease in the German healthcare system over the past decade.

OBJECTIVES: To analyze trends of in-hospital treatment of patients admitted due to peripheral artery disease (PAD) from 2009 to 2018 with special focus on comorbidities, revascularization procedures, resulting costs, and outcome. METHODS: Using data from the research data center of the German Federal Statistical Office, we included all hospitalizations due to PAD Fontaine stage IIb or higher from 2009 to 2018. To analyze comorbidities, Elixhauser diagnostic groups and linear van Walraven score (vWS) were assessed. RESULTS: A total of 1.8 million hospitalizations resulting in €10.3 billion in reimbursement costs were included. From 2009 to 2018, the absolute number of hospitalizations due to PAD increased by 13.3% (163,547 to 185,352). The average cost per hospitalization increased by 20.8% from €5,261 to €6,356. The overall in-hospital mortality decreased from 3.1 to 2.6%. Median vWS of all PAD cases increased by 3 points (2 to 5). The number of percutaneous transluminal angioplasties (PTA) increased by 43.9% while some surgical procedures such as bypasses and embolectomies decreased by 30.8% and 6.8%, respectively. Many revascularization procedures showed a disproportionate increase of those performed in vessels below the knee for example in PTA (+ 68.5%) or in endarterectomies (+ 38.8%). CONCLUSIONS: This decade-long nationwide analysis shows a rising number of hospitalizations due to PAD with more comorbid patients resulting in increasing reimbursement costs. Interventions are shifting from surgical to endovascular approaches with a notable trend towards interventions in smaller vessels below the knee. KEY POINTS: • The number of hospitalizations due to peripheral artery disease is rising and it is associated with increasing reimbursement costs. • Admitted patients are older and show an increasing number of comorbidities while overall in-hospital mortality is decreasing. • Revascularization procedures are shifting from surgical to endovascular approaches and show a trend towards intervention in smaller vessels below the knee. • Major amputations are decreasing while the number of minor amputations is increasing.

Visualization of bone details in a novel photon-counting dual-source CT scanner-comparison with energy-integrating CT.

OBJECTIVES: Photon-counting detector CT (PCD-CT) promises a leap in spatial resolution due to smaller detector pixel sizes than implemented in energy-integrating detector CTs (EID-CT). Our objective was to compare the visualization of smallest bone details between PCD-CT and EID-CT using a mouse as a specimen. MATERIALS AND METHODS: Two euthanized mice were scanned at a 20-slice EID-CT and a dual-source PCD-CT in single-pixel mode at various CTDIVol values. Image noise and signal-to-noise ratio (SNR) were evaluated using repeated ROI measurements. Edge sharpness of bones was compared by the maximal slope within CT value plots along sampling lines intersecting predefined bones of the spine. Two readers evaluated bone detail visualization at four regions of the spine on a three-point Likert scale at various CTDIVol's. Two radiologists selected the series with better detail visualization among each of 20 SNR-matched pairs of EID-CT and PCD-CT series. RESULTS: In CTDIVol-matched scans, PCD-CT series showed significantly lower image noise (NoiseCTDI=5 mGy: 16.27 ± 1.39 vs. 23.46 ± 0.96 HU, p < 0.01), higher SNR (SNRCTDI=5 mGy: 20.57 ± 1.89 vs. 14.00 ± 0.66, p < 0.01), and higher edge sharpness (Edge Slopelumbar spine: 981 ± 160 vs. 608 ± 146 HU/mm, p < 0.01) than EID-CT series. Two radiologists considered the delineation of bone details as feasible at consistently lower CTDIVol values at PCD-CT than at EID-CT. In comparison of SNR-matched reconstructions, PCD-CT series were still considered superior in almost all cases. CONCLUSIONS: In this head-to-head comparison, PCD-CT showed superior objective and subjective image quality characteristics over EID-CT for the delineation of tiniest bone details. Even in SNR-matched pairs (acquired at different CTDIVol's), PCD-CT was strongly preferred by radiologists. KEY POINTS: • In dose-matched scans, photon-counting detector CT series showed significantly less image noise, higher signal-to-noise ratio, and higher edge sharpness than energy-integrating detector CT series. • Human observers considered the delineation of tiny bone details as feasible at much lower dose levels in photon-counting detector CT than in energy-integrating detector CT. • In direct comparison of series matched for signal-to-noise ratio, photon-counting detector CT series were considered superior in almost all cases.

Impact of machine-learning-based coronary computed tomography angiography-derived fractional flow reserve on decision-making in patients with severe aortic stenosis undergoing transcatheter aortic valve replacement.

OBJECTIVES: To evaluate feasibility and diagnostic performance of coronary CT angiography (CCTA)-derived fractional flow reserve (CT-FFR) for detection of significant coronary artery disease (CAD) and decision-making in patients with severe aortic stenosis (AS) undergoing transcatheter aortic valve replacement (TAVR) to potentially avoid additional pre-TAVR invasive coronary angiography (ICA). METHODS: Consecutive patients with severe AS (n = 95, 78.6 ± 8.8 years, 53% female) undergoing pre-procedural TAVR-CT followed by ICA with quantitative coronary angiography were retrospectively analyzed. CCTA datasets were evaluated using CAD Reporting and Data System (CAD-RADS) classification. CT-FFR measurements were computed using an on-site machine-learning algorithm. A combined algorithm was developed for decision-making to determine if ICA is needed based on pre-TAVR CCTA: [1] all patients with CAD-RADS ≥ 4 are referred for ICA; [2] patients with CAD-RADS 2 and 3 are evaluated utilizing CT-FFR and sent to ICA if CT-FFR ≤ 0.80; [3] patients with CAD-RADS < 2 or CAD-RADS 2-3 and normal CT-FFR are not referred for ICA. RESULTS: Twelve patients (13%) had significant CAD (≥ 70% stenosis) on ICA and were treated with PCI. Twenty-eight patients (30%) showed CT-FFR ≤ 0.80 and 24 (86%) of those were reported to have a maximum stenosis ≥ 50% during ICA. Using the proposed algorithm, significant CAD could be identified with a sensitivity, specificity, and positive and negative predictive value of 100%, 78%, 40%, and 100%, respectively, potentially decreasing the number of necessary ICAs by 65 (68%). CONCLUSION: Combination of CT-FFR and CAD-RADS is able to identify significant CAD pre-TAVR and bears potential to significantly reduce the number of needed ICAs. KEY POINTS: • Coronary CT angiography-derived fractional flow reserve (CT-FFR) using machine learning together with the CAD Reporting and Data System (CAD-RADS) classification safely identifies significant coronary artery disease based on quantitative coronary angiography in patients prior to transcatheter aortic valve replacement. • The combination of CT-FFR and CAD-RADS enables decision-making and bears the potential to significantly reduce the number of needed invasive coronary angiographies.

Early experience with the new endovascular aneurysm sealing system Nellix: First clinical results after 50 implantations.

OBJECTIVE: In the present study, 50 EVAS procedures were evaluated in regard to primary (survival and technical success) and secondary (device-related complications) events of interest. METHODS: The single center study was conducted from July 2013 to August 2014 with prospective collection of the clinical data. The clinical results were controlled by CT angiography and contrast-enhanced ultrasound. RESULTS: The technical success was 98% and the 30-day mortality 4%. One (2%) patient died from multisystem organ failure and another patient from an intracranial bleeding, respectively. One patient (2%) suffered from a device-related aneurysm rupture. During early follow-up, one (2%) patient developed an endoleak type II, while three (6%) patients suffered from a partial endograft limb thrombosis. Overall, a secondary intervention was necessary in six (12%) patients. CONCLUSIONS: With the Nellix EVAS system, a high primary technical success of 98% was achieved; one (2%) patient developed an endoleak type II which did not require secondary intervention. Those promising results are contrasted by a substantial rate of endograft limb thromboses (8%) and one (2%) intraoperative aneurysm rupture. Further studies are needed to assess the durability of the Nellix stentgraft and the occurrence of device-related complications.

MR elastography of the liver and the spleen using a piezoelectric driver, single-shot wave-field acquisition, and multifrequency dual parameter reconstruction.

PURPOSE: Viscoelastic properties of the liver are sensitive to fibrosis. This study proposes several modifications to existing magnetic resonance elastography (MRE) techniques to improve the accuracy of abdominal MRE. METHODS: The proposed method comprises the following steps: (i) wave generation by a nonmagnetic, piezoelectric driver suitable for integration into the patient table, (ii) fast single-shot 3D wave-field acquisition at four drive frequencies between 30 and 60 Hz, and (iii) single-step postprocessing by a novel multifrequency dual parameter inversion of the wave equation. The method is tested in phantoms, healthy volunteers, and patients with portal hypertension and ascites. RESULTS: Spatial maps of magnitude and phase of the complex shear modulus were acquired within 6-8 min. These maps are not subject to bias from inversion-related artifacts known from classic MRE. The spatially averaged modulus for healthy liver was 1.44 ± 0.23 kPa with ϕ = 0.492 ± 0.064. Both parameters were significantly higher in the spleen (2.29 ± 0.97 kPa, P = 0.015 and 0.749 ± 0.144, P = 6.58·10(-5) , respectively). CONCLUSION: The proposed method provides abdominal images of viscoelasticity in a short time with spatial resolution comparable to conventional MR images and improved quality without being compromised by ascites. The new setup allows for the integration of abdominal MRE into the clinical workflow.

Towards compression-sensitive magnetic resonance elastography of the liver: sensitivity of harmonic volumetric strain to portal hypertension.

PURPOSE: To assess induced oscillating volumetric strain as a biomarker for intrahepatic blood pressure abnormalities. MATERIALS AND METHODS: Harmonic vibrations of 25 and 50 Hz frequency were induced in the liver and measured by fast 3D vector field magnetic resonance elastography (MRE), followed by processing of the decomposed curl (shear) and divergence (compression) fields. After an initial study on an excised sheep liver, a group of 13 patients with hepatic hypertension were examined before and after implantation of a transjugular intrahepatic portosystemic shunt (TIPS). RESULTS: In the sheep liver specimen, volumetric strain decreased with excess portal pressure, whereas shear strain was not sensitive to portal pressure. In the patient cohort, volumetric strain was significantly higher after TIPS placement (P = 1.38·10(-5) ), while neither shear strain nor the shear modulus were affected. Normalized changes in volumetric strain were significantly correlated with the hepatic venous pressure gradient (R(2) = 0.7258, P = 6.95·10(-5) ) and portal venous pressure (R(2) = 0.5028, P = 0.0016). CONCLUSION: These results indicate for the first time the sensitivity of volumetric strain to symptomatically high values of tissue pressure and motivate further developments in compression-sensitive MRE and poroelastography towards image-based and noninvasive markers of tissue pressure.

Uterine artery embolization in single symptomatic leiomyoma: do anatomical imaging criteria predict clinical presentation and long-term outcome?

BACKGROUND: Uterine artery embolization (UAE) has proven to be an effective treatment alternative for women suffering from symptomatic uterine leiomyomas. However, long-term clinical evaluation reveals treatment failure in approximately 25% of patients. To cope with the great variability in the extent of leiomyoma disease former studies are based on the simplifying assumption that the largest leiomyoma mainly causes the symptoms. PURPOSE: To evaluate whether anatomical characteristics in women with a single symptomatic leiomyoma influence clinical presentation and outcome after UAE. MATERIAL AND METHODS: Ninety-one patients with a single leiomyoma underwent UAE. Age, uterine and fibroid volume, fibroid location, and clinical symptoms (bleeding- and/or bulk-related symptoms) were documented. The need for reinterventions (i.e. repeat UAE, hysterectomy, myomectomy) and unchanged or worsened symptoms after UAE were classified as treatment failure (TF). Contrast-enhanced magnetic resonance imaging (MRI) 48-72 h after UAE was available in 38 women. The rate of fibroid infarction was determined and patients were assigned to one of three groups: complete (100%), almost complete (90-99%), or partial infarction (<90%). Cox regression analysis (CRA) was used to determine the influence of morphological and clinical parameters on outcome. RESULTS: Follow-up was available in 79/91 (87%) women (median age, 42 years; range, 33-56 years) at a median of 5 years (range, 3.1-9.2 years) after UAE. Anatomical leiomyoma criteria neither connected to specific clinical presentation nor influenced clinical outcome. Younger women showed a higher risk for TF with every year older lowering the risk by the factor of 0.86 (P = 0.024). Subgroup analysis showed predictive value of fibroid infarction with a cumulative survival free from TF of 91% for complete vs. 0% for partial infarction (P < 0.001). CONCLUSION: Even in women with single leiomyomas, anatomical criteria do not specify clinical presentation or predict clinical outcome. Younger patient age and incomplete fibroid infarction relate to higher rates of TF.

Discrimination of Hemorrhage and Contrast Media in a Head Phantom on Photon-Counting Detector CT Data.

In this anthropomorphic head phantom study, samples containing blood and contrast agent with concentrations ranging from 0 to 6 mg iodine per milliliter and another set of samples without blood for reference were scanned with a photon-counting detector CT using a standard cranial protocol. It was demonstrated that photon-counting detector CT can reliably distinguish hemorrhage and contrast media, including density determination of the latter. The technology promises to add value in several neuroimaging applications.

Optimal conspicuity of pancreatic ductal adenocarcinoma in virtual monochromatic imaging reconstructions on a photon-counting detector CT: comparison to conventional MDCT.

PURPOSE: To analyze the conspicuity of pancreatic ductal adenocarcinoma (PDAC) in virtual monoenergetic images (VMI) on a novel photon-counting detector CT (PCD-CT) in comparison to energy-integrating CT (EID-CT). METHODS: Inclusion criteria comprised initial diagnosis of PDAC (reference standard: histopathological analysis) and standardized contrast-enhanced CT imaging either on an EID-CT or a PCD-CT. Patients were excluded due to different histopathological diagnosis or missing tumor delineation on CT. On the PCD-CT, 40-190 keV VMI reconstructions were generated. Image noise, tumor-to-pancreas ratio (TPR) and contrast-to-noise ratio (CNR) were analyzed by ROI-based measurements in arterial and portal venous contrast phase. Two board-certified radiologist evaluated image quality and tumor delineation at both, EID-CT and PCD-CT (40 and 70 keV). RESULTS: Thirty-eight patients (mean age 70.4 years ± 10.3 [range 45-91], 27 males; PCD-CT: n=19, EID-CT: n=19) were retrospectively included. On the PCD-CT, tumor conspicuity (reflected by low TPR and high CNR) was significantly improved at low-energy VMI series (≤ 70 keV compared to > 70 keV), both in arterial and in portal venous contrast phase (P < 0.001), reaching the maximum at 40 keV. Comparison between PCD-CT and EID-CT showed significantly higher CNR on the PCD-CT in portal venous contrast phase at < 70 keV (P < 0.016). On the PCD-CT, tumor conspicuity was improved in portal venous contrast phase compared to arterial contrast phase especially at the lower end of the VMI spectrum (≤ 70 keV). Qualitative analysis revealed that tumor delineation is improved in 40 keV reconstructions compared to 70 keV reconstructions on a PCD-CT. CONCLUSION: PCD-CT VMI reconstructions (≤ 70 keV) showed significantly improved conspicuity of PDAC in quantitative and qualitative analysis in both, arterial and portal venous contrast phase, compared to EID-CT, which may be important for early detection of tumor tissue in clinical routine. Tumor delineation was superior in portal venous contrast phase compared to arterial contrast phase.

Radiomics-Based Machine Learning Model for Diagnosis of Acute Pancreatitis Using Computed Tomography.

In the early diagnostic workup of acute pancreatitis (AP), the role of contrast-enhanced CT is to establish the diagnosis in uncertain cases, assess severity, and detect potential complications like necrosis, fluid collections, bleeding or portal vein thrombosis. The value of texture analysis/radiomics of medical images has rapidly increased during the past decade, and the main focus has been on oncological imaging and tumor classification. Previous studies assessed the value of radiomics for differentiating between malignancies and inflammatory diseases of the pancreas as well as for prediction of AP severity. The aim of our study was to evaluate an automatic machine learning model for AP detection using radiomics analysis. Patients with abdominal pain and contrast-enhanced CT of the abdomen in an emergency setting were retrospectively included in this single-center study. The pancreas was automatically segmented using TotalSegmentator and radiomics features were extracted using PyRadiomics. We performed unsupervised hierarchical clustering and applied the random-forest based Boruta model to select the most important radiomics features. Important features and lipase levels were included in a logistic regression model with AP as the dependent variable. The model was established in a training cohort using fivefold cross-validation and applied to the test cohort (80/20 split). From a total of 1012 patients, 137 patients with AP and 138 patients without AP were included in the final study cohort. Feature selection confirmed 28 important features (mainly shape and first-order features) for the differentiation between AP and controls. The logistic regression model showed excellent diagnostic accuracy of radiomics features for the detection of AP, with an area under the curve (AUC) of 0.932. Using lipase levels only, an AUC of 0.946 was observed. Using both radiomics features and lipase levels, we showed an excellent AUC of 0.933 for the detection of AP. Automated segmentation of the pancreas and consecutive radiomics analysis almost achieved the high diagnostic accuracy of lipase levels, a well-established predictor of AP, and might be considered an additional diagnostic tool in unclear cases. This study provides scientific evidence that automated image analysis of the pancreas achieves comparable diagnostic accuracy to lipase levels and might therefore be used in the future in the rapidly growing era of AI-based image analysis.

Virtual non-contrast series of photon-counting detector computed tomography angiography for aortic valve calcium scoring.

The aim of our study was to evaluate two different virtual non-contrast (VNC) algorithms applied to photon counting detector (PCD)-CT data in terms of noise, effectiveness of contrast media subtraction and aortic valve calcium (AVC) scoring compared to reference true non-contrast (TNC)-based results. Consecutive patients underwent TAVR planning examination comprising a TNC scan, followed by a CTA of the heart. VNC series were reconstructed using a conventional (VNCconv) and a calcium-preserving (VNCpc) algorithm. Noise was analyzed by means of the standard deviation of CT-values within the left ventricle. To assess the effectiveness of contrast media removal, heart volumes were segmented and the proportion of their histograms > 130HU was taken. AVC was measured by Agatston and volume score. 41 patients were included. Comparable noise levels to TNC were achieved with all VNC reconstructions. Contrast media was effectively virtually removed (proportions > 130HU from 81% to < 1%). Median calcium scores derived from VNCconv underestimated TNC-based scores (up to 74%). Results with smallest absolute difference to TNC were obtained with VNCpc reconstructions (0.4 mm, Br36, QIR 4), but with persistent significant underestimation (median 29%). Both VNC algorithms showed near-perfect (r²>0.9) correlation with TNC. Thin-slice VNC reconstructions provide equivalent noise levels to standard thick-slice TNC series and effective virtual removal of iodinated contrast. AVC scoring was feasible on both VNC series, showing near-perfect correlation, but with significant underestimation. VNCpc with 0.4 mm slices and Br36 kernel at QIR 4 gave the most comparable results and, with further advances, could be a promising replacement for additional TNC.

Imaging Markers Derived From MRI-Based Automated Kidney Segmentation.

BACKGROUND: Population-wide research on potential new imaging biomarkers of the kidney depends on accurate automated segmentation of the kidney and its compartments (cortex, medulla, and sinus). METHODS: We developed a robust deep-learning framework for kidney (sub-)segmentation based on a hierarchical, three-dimensional convolutional neural network (CNN) that was optimized for multiscale problems of combined localization and segmentation. We applied the CNN to abdominal magnetic resonance images from the population-based German National Cohort (NAKO) study. RESULTS: There was good to excellent agreement between the model predictions and manual segmentations. The median values for the body-surface normalized total kidney, cortex, medulla, and sinus volumes of 9934 persons were 158, 115, 43, and 24 mL/m2. Distributions of these markers are provided both for the overall study population and for a subgroup of persons without kidney disease or any associated conditions. Multivariable adjusted regression analyses revealed that diabetes, male sex, and a higher estimated glomerular filtration rate (eGFR) are important predictors of higher total and cortical volumes. Each increase of eGFR by one unit (i.e., 1 mL/min per 1.73 m2 body surface area) was associated with a 0.98 mL/m2 increase in total kidney volume, and this association was significant. Volumes were lower in persons with eGFR-defined chronic kidney disease. CONCLUSION: The extraction of image-based biomarkers through CNN-based renal sub-segmentation using data from a population-based study yields reliable results, forming a solid foundation for future investigations.

Clinical long-term outcome after uterine artery embolization: sustained symptom control and improvement of quality of life.

PURPOSE: To evaluate long-term clinical efficacy of uterine artery embolization (UAE) for uterine fibroids with respect to symptom control and improvement in quality of life. MATERIALS AND METHODS: Between October 2000 and October 2007, 380 consecutive women underwent UAE. To determine long-term efficacy, the rate of reinterventions (ie, repeat UAE, hysterectomy, myomectomy) and the clinical response regarding symptoms related to bleeding and bulk were documented. Persistence, worsening, or recurrence of symptoms and reinterventions were classified as treatment failure (TF). The cumulative rate of freedom from TF was determined by Kaplan-Meier analysis. Cox regression was used to identify possible clinical or morphologic predictors of outcome. Secondary outcome measures were changes in disease-specific quality of life and onset of menopause. RESULTS: Follow-up was available for a median of 5.7 years (range, 3.1-10.1 y) after treatment in 304 of 380 (80%) patients. There were 54 TFs with subsequent reintervention in 46 women. Kaplan-Meier analysis revealed a cumulative TF rate of 23.3% after 10 years. Cox regression demonstrated a significantly higher likelihood of TF in patients<40 years old compared with patients>45 years old (hazard ratio, 2.28; P = .049). Women without TF showed sustained normalization of disease-specific quality of life (P <.001). Cessation of menstruation at a median age of 51 years was reported by 57 (22.8%) of 250 women. CONCLUSIONS: UAE leads to long-term control of fibroid-related symptoms and normalization of quality of life in approximately 75% of patients. Younger women seem to have a higher risk of TF than older women closer to menopause.

Nationwide Trends and the Influence of Age and Gender in the In-Patient Care of Patients with Hepatocellular Carcinoma in Germany between 2010 and 2020.

This study analyzes nationwide trends in HCC hospitalizations focusing on interventional liver-directed treatments and the influence of age and gender. Using data from the German Federal Statistical Office all hospitalizations for HCC between 2010 and 2020 were included. Uni- and multivariable logistic regression analyses were performed to identify variables independently associated with the use of liver-directed therapies. Due to the COVID-19 pandemic, data from 2020 were analyzed separately. A total of 134,713 hospitalizations (2010-2019) were included, increasing by 3.4% annually (12,707 to 13,143). The mean in-hospital stay (-15.0% [7.2 to 6.1 days]) and mortality (-23.2% [6.8 to 5.2%]) decreased while transarterial, surgical, and percutaneous ablative interventions increased by 38.6, 31.5, and 19.3%, respectively. In-hospital mortality was 7.7% in admissions with surgical treatment, while it was 0.6 and 0.5% for transarterial and percutaneous interventions. Mortality was higher in females (6.2 vs. 5.7%). Females (OR 0.89 [0.86,0.91], p < 0.001) and patients ≥80 years (OR 0.81 [0.79,0.84], p < 0.001) were less likely to receive liver-directed treatments. Liver-directed therapies were increasingly performed while in-hospital mortality and in-hospital stay decreased. Minimally invasive approaches showed lower mortality, shorter in-hospital stay, and lower costs compared to surgery. Proportionately, more women and older patients were hospitalized, receiving fewer liver-directed treatments while their mortality was higher.