MR Enterography in Ulcerative Colitis: Beyond Endoscopy.

Ulcerative colitis (UC) is a chronic idiopathic inflammatory bowel disease (IBD) that progressively affects mucosa and submuccosa of the colon and rectum in a continual pattern. In comparison, Crohn disease (CD), the other type of IBD, is a chronic transmural inflammatory disorder that can involve any part of the gastrointestinal tract. MR enterography (MRE) has emerged as an important imaging modality for the diagnosis and detection of disease activity and complications in CD, with comparable results to those of endoscopy. But MRE has been underused for assessment of UC in recent years, and clinicians heavily rely on endoscopic findings for management of UC. Despite UC being considered an endoscopically assessable disease, MRE can provide useful information beyond that obtained with endoscopy about mural or extramural abnormalities, inaccessible parts of the colonic lumen, associated extraintestinal diseases, and superimposed pathologic conditions. Moreover, endoscopy might be contraindicated in some clinical settings due to the risk of colonic perforation. In addition to depicting the features of UC activity in different phases, MRE demonstrates findings of disease chronicity that cannot be achieved with endoscopy, particularly in a patient with colitis of unknown cause. The valuable diagnostic role of MRE to exclude undiagnosed CD in patients with UC who have refractory disease or those with postproctocolectomy complications is also emphasized. Radiologists can play a crucial role in the management of UC with MRE by addressing what is beyond endoscopy. ©RSNA, 2023 Test Your Knowledge questions are available in the supplemental material.

Performing Quality Control on Magnetic Resonance Imaging Liver Fat/Iron Quantification Studies: A Critical Requirement.

OBJECTIVE: Nonalcoholic fatty liver and iron overload can lead to cirrhosis requiring early detection. Magnetic resonance (MR) imaging utilizing chemical shift-encoded sequences and multi-Time of Echo single-voxel spectroscopy (SVS) are frequently used for assessment. The purpose of this study was to assess various quality factors of technical acceptability and any deficiencies in technologist performance in these fat/iron MR quantification studies. METHODS: Institutional review board waived retrospective quality improvement review of 87 fat/iron MR studies performed over a 6-month period was evaluated. Technical acceptability/unacceptability for chemical shift-encoded sequences (q-Dixon and IDEAL-IQ) included data handling errors (missing maps), liver field coverage, fat/water swap, motion, or other artifacts. Similarly, data handling (missing table/spectroscopy), curve-fit, fat- and water-peak separation, and water-peak sharpness were evaluated for SVS technical acceptability. RESULTS: Data handling errors were found in 11% (10/87) of studies with missing maps or entire sequence (SVS or q-Dixon). Twenty-seven percent (23/86) of the q-Dixon/IDEAL-IQ were technically unacceptable (incomplete liver-field [39%], other artifacts [35%], significant/severe motion [18%], global fat/water swap [4%], and multiple reasons [4%]). Twenty-eight percent (21/75) of SVS sequences were unacceptable (water-peak broadness [67%], poor curve-fit [19%] overlapping fat and water peaks [5%], and multiple reasons [9%]). CONCLUSIONS: A high rate of preventable errors in fat/iron MR quantification studies indicates the need for routine quality control and evaluation of technologist performance and technical deficiencies that may exist within a radiology practice. Potential solutions such as instituting a checklist for technologists during each acquisition procedure and routine auditing may be required.

Hepatocellular Carcinoma With Atypical Imaging Features: Review of the Morphologic Hepatocellular Carcinoma Subtypes With Radiology-Pathology Correlation.

Hepatocellular carcinoma (HCC) is the fastest growing cause of cancer death in the United States with the incidence rate more than doubling in 20 years. HCC is unique since a noninvasive diagnosis can be achieved with imaging alone when specific clinical criteria and imaging characteristics are met, obviating the need for tissue sampling. However, HCC is a highly heterogeneous neoplasm. Atypical HCC subtypes vary significantly in their morphology, which can be attributed to specific histologic and molecular features, and can cause deviations from the classic imaging characteristics. The different morphologic subtypes of HCC frequently present a diagnostic challenge for radiologists and pathologists since their imaging and pathologic features can overlap with those of non-HCC malignancies. Identifying an atypical subtype can have important clinical implications. Liver transplant, albeit a scarce and limited resource, is the optimal treatment for conventional HCC, potentially curing both the tumor and the underlying pre-malignant condition. Some HCC subtypes as well as mimickers are associated with unacceptably high recurrence and poor outcome after transplant, and there remains limited data on the role and prognosis of liver transplantation for treatment of rare HCC subtypes. Other subtypes tend to recur later than classic HCC, potentially requiring a different follow-up scheme. This review will discuss the appearance of different HCC subtypes in relation to their histopathologic features. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY: Stage 3.

Pancreaticoduodenal Groove: Spectrum of Disease and Imaging Features.

The pancreaticoduodenal groove (PDG) is a small space between the pancreatic head and duodenum where vital interactions between multiple organs and physiologic processes take place. Muscles, nerves, and hormones perform a coordinated dance, allowing bile and pancreatic enzymes to aid in digestion and absorption of critical nutrition. Given the multitude of organs and cells working together, a variety of benign and malignant entities can arise in or adjacent to this space. Management of lesions in this region is also complex and can involve observation, endoscopic resection, or challenging surgeries such as the Whipple procedure. The radiologist plays an important role in evaluation of abnormalities involving the PDG. While CT is usually the first-line examination for evaluation of this complex region, MRI offers complementary information. Although features of abnormalities involving the PDG can often overlap, understanding the characteristic imaging and pathologic features generally allows categorization of disease entities based on the suspected organ of origin and the presence of ancillary features. The goal of the authors is to provide radiologists with a conceptual approach to entities implicating the PDG to increase the accuracy of diagnosis and assist in appropriate management or presurgical planning. They briefly discuss the anatomy of the PDG, followed by a more in-depth presentation of the features of disease categories. A table summarizing the entities that occur in this region by underlying cause and anatomic location is provided. ©RSNA, 2022.

Case 282: Fishbone Pylephlebitis.

HistoryA 63-year-old woman with a history of left mastectomy for breast cancer and partial gastrectomy with Roux-en-Y reconstruction for nonhealing peptic ulcer presented to the emergency department and reported a 1-month history of abdominal distention, fevers, chills, and flu-like symptoms. She was initially suspected of having flu, and she completed a course of oseltamivir; however, she had continued to experience fatigue, fever, chills, abdominal bloating, and loss of appetite. She reported no contact with a sick person or recent travel. At admission, laboratory studies revealed leukocytosis, with a white blood cell count of 15.1 × 103/µL (15.1 × 109/L) (normal range, 4.0-10.0 × 103/µL [4.0-10.0 × 109/L]), an elevated sedimentation rate of 100 mm per hour (normal range, 0-30 mm per hour), and a C-reactive protein level of 203.8 mg/L (1940.9 nmol/L) (normal range, ≤10 mg/L [≤95.2 nmol/L]). Liver enzyme levels were elevated, with an alanine aminotransferase level of 48 U/L (0.80 µkat/L) (normal range, 0-29 U/L [0-0.48 µkat/L]), an aspartate aminotransferase level of 98 U/L (1.6 µkat/L) (normal range, 10-37 U/L [0.16-0.62 µkat/L]), an alkaline phosphatase level of 682 U/L (11.4 µkat/L) (normal range, 65-195 U/L [1.1-3.3 µkat/L]), and a total bilirubin level of 1.5 mg/dL (25.7 µmol/L) (normal range, 0.3-1.0 mg/dL [5.1-17.1 µmol/L]). Abdominopelvic CT was performed.

Case 282.

HistoryA 63-year-old woman with a history of left mastectomy for breast cancer and partial gastrectomy with Roux-en-Y reconstruction for nonhealing peptic ulcer presented to the emergency department and reported a 1-month history of abdominal distention, fevers, chills, and flu-like symptoms. She was initially suspected of having flu, and she completed a course of oseltamivir; however, she had continued fatigue, fever, chills, abdominal bloating, and loss of appetite. She reported no contact with a sick person or recent travel. At admission, laboratory studies revealed leukocytosis, with a white blood cell count of 15.1 × 103/µL (15.1 × 109/L) (normal range, 4.0-10.0 × 103/µL [4.0-10.0 × 109/L]), an elevated sedimentation rate of 100 mm per hour (normal range, 0-30 mm per hour), and a C-reactive protein level of 203.8 mg/L (1940.9 nmol/L) (normal range, ≤10 mg/L [≤95.2 nmol/L]). Liver enzyme levels were elevated, with an alanine aminotransferase level of 48 U/L (0.80 µkat/L) (normal range, 0-29 U/L [0-0.48 µkat/L]), an aspartate aminotransferase level of 98 U/L (1.6 µkat/L) (normal range, 10-37 U/L [0.16-0.62 µkat/L]), an alkaline phosphatase level of 682 U/L (11.4 µkat/L) (normal range, 65-195 U/L [1.1-3.3 µkat/L]), and a total bilirubin level of 1.5 mg/dL (25.7 µmol/L) (normal range, 0.3-1.0 mg/dL [5.1-17.1 µmol/L]). Abdominopelvic CT was performed (Figs 1-3).

Sofosbuvir and daclatasvir compared with standard of care in the treatment of patients admitted to hospital with moderate or severe coronavirus infection (COVID-19): a randomized controlled trial.

BACKGROUND: Currently no effective antiviral therapy has been found to treat COVID-19. The aim of this trial was to assess if the addition of sofosbuvir and daclatasvir improved clinical outcomes in patients with moderate or severe COVID-19. METHODS: This was an open-label, multicentre, randomized controlled clinical trial in adults with moderate or severe COVID-19 admitted to four university hospitals in Iran. Patients were randomized into a treatment arm receiving sofosbuvir and daclatasvir plus standard care, or a control arm receiving standard care alone. The primary endpoint was clinical recovery within 14 days of treatment. The study is registered with IRCT.ir under registration number IRCT20200128046294N2. RESULTS: Between 26 March and 26 April 2020, 66 patients were recruited and allocated to either the treatment arm (n = 33) or the control arm (n = 33). Clinical recovery within 14 days was achieved by 29/33 (88%) in the treatment arm and 22/33 (67%) in the control arm (P = 0.076). The treatment arm had a significantly shorter median duration of hospitalization [6 days (IQR 4-8)] than the control group [8 days (IQR 5-13)]; P = 0.029. Cumulative incidence of hospital discharge was significantly higher in the treatment arm versus the control (Gray's P = 0.041). Three patients died in the treatment arm and five in the control arm. No serious adverse events were reported. CONCLUSIONS: The addition of sofosbuvir and daclatasvir to standard care significantly reduced the duration of hospital stay compared with standard care alone. Although fewer deaths were observed in the treatment arm, this was not statistically significant. Conducting larger scale trials seems prudent.

Homogeneous T1 Hyperintense Renal Lesions with Smooth Borders: Is Contrast-enhanced MR Imaging Needed?

Purpose To retrospectively determine if homogeneous high T1 signal intensity (SI) masses with smooth borders on unenhanced magnetic resonance (MR) images can be characterized as benign. Materials and Methods Institutional review board approval was obtained for this HIPAA-compliant retrospective study, with waiver of informed consent. MR images in 84 patients with hemorrhagic or proteinaceous cysts and 50 patients with renal cell carcinoma (RCC) were evaluated. Sixty-three cysts and 49 RCCs underwent unenhanced computed tomography (CT). SI ratio and CT attenuation were determined. Two radiologists evaluated lesions as follows: score 1, homogeneous with smooth borders; score 2, mildly heterogeneous with mildly lobulated borders; score 3, moderately heterogeneous and irregular borders; and score 4, markedly heterogeneous with markedly irregular borders. Statistical analysis was performed by using multivariable logistic regression, Welch t test, Z test, Fisher-exact test, Shapiro-Wilk test, and receiver operating characteristic curve analysis. A diagnostic criterion was formulated by using classification and regression tree analysis. Results SI ratio and attenuation of hemorrhagic or proteinaceous cysts were significantly higher than those of RCCs (SI ratio: cyst 2.4 ± 0.8, RCC 1.5 ± 0.3; attenuation: cyst 51.9 ± 21.5, RCC: 34.8 ± 10.0). Reader 1 scored morphology of 68 (81%) hemorrhagic or proteinaceous cysts as score 1 on MR images and as score 45 (71%) on CT scans. Reader 2 scored morphology of 59 (70%) hemorrhagic or proteinaceous cysts as score 1 on MR images and as score 43 (68%) on CT scans. Two-step classification tree suggested that homogeneous high T1 SI lesions with smooth borders and SI ratio of greater than 1.6 predict the lesion as benign cysts. Similar algorithm for CT suggested threshold of 51 HU. Increasing threshold to 2.5 for SI ratio and 66 for Hounsfield units resulted in 99.9% confidence for characterizing benign cysts. Conclusion The retrospective assessment shows that morphologic assessment and SI quantification on unenhanced T1-weighted MR images can be used to differentiate benign hemorrhagic or proteinaceous cysts from RCC, although prospective assessment will be needed to confirm these results. (©) RSNA, 2016.

Differential effect of atorvastatin and pravastatin on thoracic spine attenuation: A sub-analysis of a randomized clinical trial.

BACKGROUND: Statins reduce cardiovascular events and may improve bone mineral density. METHODS: We conducted a sub-analysis of a randomized clinical trial that investigated the differential effect of moderate vs intensive low-density lipoprotein cholesterol (LDL-C) lowering therapies on coronary artery calcium (CAC) scores, and used the acquired images to assess the change in radiological attenuation of selected thoracic vertebrae. Baseline and 12-month unenhanced chest CT scans were performed in 420 hyperlipidemic, postmenopausal women randomized to atorvastatin (ATV) 80 mg/day or pravastatin (PRV) 40 mg/day in the Beyond Endorsed Lipid Lowering with Electron Beam Tomography Scanning (BELLES) trial. Bone attenuation was measured in three contiguous thoracic vertebrae at baseline and 12 months. RESULTS: There were no differences in baseline demographic and clinical characteristics between treatment arms. The median percent lowering (interquartile range) in LDL-C was significantly greater with ATV than PRV [-53 (-69 to 20)% vs -28 (-55 to 74)%, p < 0.001], although the CAC score change was similar [12 (-63 to 208)% vs 13 (-75 to 358)%; p = 0.44]. At follow-up, the median bone attenuation loss was significantly greater with PRV than with ATV [-2.6 (-27 to 11)% vs 0 (-11 to 25)%; p < 0.001]. The attenuation loss in the PRV group was comparable to that of a historical untreated general population sample. In the entire cohort, the changes in LDL-C and total cholesterol were inversely correlated with bone attenuation change (p < 0.01). In adjusted multivariable linear regression analyses, race and percent change in LDL-C were independent predictors of bone attenuation change. Age, body mass index, history of smoking, diabetes mellitus, hypertension, peripheral vascular disease, or hormone replacement therapy did not affect percent change in BMD. CONCLUSIONS: These findings support the hypothesis that there is an interaction between bone and cardiometabolic health and that intensive lipid lowering has a beneficial effect on bone health.

The role of imaging in hepatocellular carcinoma: the present and future.

Imaging plays an important role in diagnosis and management of patients with hepatocellular carcinoma (HCC). Although ultrasound is the main surveillance imaging tool for HCC, dynamic contrast-enhanced computed tomography (CT) and magnetic resonance imaging (MRI) are used primarily for diagnosis and staging of HCC. Recent advances in both CT and MRI technology have led to a decrease in ionizing radiation exposure and improved capabilities for evaluation of HCC, including, dynamic contrast-enhanced CT and MRI, perfusion CT and MRI, dual-energy CT, radiation dose reduction strategies, diffusion-weighted imaging, MR elastography, iron and fat quantification, and intravenous hepatobiliary contrast agents.

CT angiography in potential living kidney donors: 80 kVp versus 120 kVp.

OBJECTIVE: The purpose of this article is to retrospectively investigate the diagnostic accuracy, image quality, and radiation dose of renal artery CT angiography (CTA), at 80 kVp compared with 120 kVp, in adult kidney donors. MATERIALS AND METHODS: CTA examinations of 258 consecutive potential kidney donors were retrospectively evaluated; 189 patients were scanned using 64-MDCT scanners (higher maximal tube current), and 69 patients were scanned using 16-MDCT scanners (lower maximal tube current). On the basis of the tube potential and scanners, the study population was divided into four groups. Qualitative and quantitative analysis include vascular attenuation measurements, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). Volume CT dose index (CTDIvol) was recorded, and size-specific dose estimate was also estimated. RESULTS: Using 80 kVp for the 16-MDCT scanner, there was a 64.9% reduction in size-specific dose estimate (66.1% reduction in CTDIvol), increased noise, and tube current saturation in all cases. Axial image quality was significantly lower compared with that obtained at 120 kVp (p = 0.02), but image quality and visibility of renal artery branch order were comparable. Using 80 kVp for the 64-MDCT scanner, there was a 40.5% reduction in size-specific dose estimate (43.6% reduction in CTDIvol) and increased SNR and CNR (p < 0.001). No significant differences in 3D image quality and branch order visibility were observed. Tube current saturation was reached in 31% of cases. One hundred fifty-one patients (86 imaged at 80 kVp and 65 imaged at 120 kVp) underwent donor nephrectomy; CTA diagnostic accuracy was 100%. CONCLUSION: Renal artery CTA using 80 kVp combined with limiting the tube current results in a significant reduction in radiation dose and improved SNR and CNR, without deterioration of image quality.

ACR Appropriateness Criteria ® imaging of mesenteric ischemia.

Mesenteric ischemia is a rare disease associated with high morbidity and mortality. Acute mesenteric ischemia is most commonly secondary to embolism followed by arterial thrombosis, nonocclusive ischemia, and less commonly venous thrombosis. Chronic mesenteric ischemia is almost always caused by atherosclerotic disease, with rare causes including fibromuscular dysplasia and vasculitis. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances where evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment. Patients with mesenteric ischemia usually present with nonspecific abdominal symptoms and laboratory findings. This document evaluates and rates the appropriateness of imaging to evaluate patients with clinically suspected mesenteric ischemia. While catheter-based angiography has been considered the reference standard and enables diagnosis and treatment, advances in computed tomography have made it a first-line test in many patients because it is a fast, widely available, and noninvasive study. Abdominal radiographs and ultrasound have a limited role in diagnosing mesenteric ischemia but are commonly the first ordered tests in patients with abdominal pain and may diagnose more common pathologies.

Inline directionally independent peak velocity evaluation reduces error in peak antegrade velocity estimation in patients referred for cardiac valvular assessment.

OBJECTIVE: The purpose of this article is to evaluate the utility of a tool in quantifying the peak antegrade velocity when assessing patients with cardiac valvular pathology. MATERIALS AND METHODS: Directionally independent peak velocity evaluation (MaxVelocity, Siemens Healthcare) phase-contrast cardiac MRI was performed for 44 patients referred to our institution with a diagnosis or concern for aortic valvular disease or undergoing imaging for thoracic aortic aneurysm. In addition, standard through-plane phase-contrast MR angiography at the level of the aortic valve was performed. The MaxVelocity technique provides a simple tool to extract the magnitude of the peak velocity, independently of its direction, from phase-contrast imaging with velocity encoding. Recent echocardiography (within 1 month) and assessment of peak forward velocity at the level of the aortic valve were required for inclusion in the study. RESULTS: The MaxVelocity technique shows significantly lower error in estimating peak antegrade velocity at the level of the aortic valve than does standard unidirectional through-plane phase-contrast MRI, using transthoracic echocardiography as the reference noninvasive imaging method. CONCLUSION: Relative to standard through-plane imaging, MaxVelocity more closely approximates echocardiography for noninvasive assessment of peak antegrade velocity. Improved accuracy is critical for surgical decision making in patients with aortic valvular disease. Therefore, MaxVelocity provides an easy approach to quantify peak velocity as part of a routine clinical MRI protocol.

Feasibility of Hepatic T1-Mapping and Extracellular Volume Quantification on Routine Cardiac Magnetic Resonance Imaging in Patients with Infiltrative and Systemic Disorders.

RATIONALE AND OBJECTIVES: Cardiac magnetic resonance imaging (CMR) is commonly obtained to evaluate for myocardial infiltrative disorders and fibrosis. Pre- and post-Gadolinium contrast T1-mapping sequences are employed to estimate interstitial expansion using extracellular volume fraction (ECV). Given the proximity of the liver to the heart, T1 and ECV quantification of the liver is feasible on CMR. The purpose of this study was to evaluate for hepatic measures of fibrosis and interstitial expansion in patients with amyloidosis or systemic disease on CMR. MATERIALS AND METHODS: Myocardial and hepatic native T1 values were measured retrospectively using a cardiac short axis modified Look-Locker inversion recovery sequence. Myocardial and hepatic ECV were calculated using pre- and post-contrast T1 and blood pool values according to the following formula: ECV = (Δ(1/T1) myocardium or liver and/or Δ(1/T1) blood)x(1 - hematocrit). Patients were divided into three cohorts by final diagnosis: amyloidosis, systemic disease (e.g. sarcoid, scleroderma), and controls (EF > 50, no ischemia). RESULTS: Of the 135 patients who underwent CMR, 22 had cardiac amyloidosis (age 59.9 ± 12.6 yrs, 41% female), 20 had systemic disease (age 50.9 ± 13.4 yrs, 35% female), and 93 were controls (age 49.5 ± 17.3 yrs, 50% female). Myocardial T1 and ECV values were highest for patients with amyloid, second highest for systemic disease, and least for controls (T1: 1169 ± 92 vs 1101 ± 53 vs 1027 ± 73 ms, p < 0.0001; ECV: 0.47 ± 0.11 vs 0.31 ± 0.05 vs 0.27 ± 0.04, p < 0.0001). Hepatic T1 and ECV were similarly higher in patients with amyloid and systemic disease compared to controls (T1: 646 ± 101 vs 660 ± 93 vs 595 ± 58 ms, p < 0.0001; ECV: 0.38 ± 0.08 vs 0.37 ± 0.05 vs 0.31 ± 0.03, p < 0.0001). There was a positive correlation between hepatic T1 and ECV (R2 = 0.282, p < 0.0001). No patients had abnormal liver function tests or clinical liver disease. CONCLUSION: Hepatic ECV quantification on CMR in patients with amyloidosis and systemic disorders is feasible. Further longitudinal investigation regarding detection of early or subclinical liver disease is warranted.

Imaging of intestinal vasculitis focusing on MR and CT enterography: a two-way street between radiologic findings and clinical data.

Diagnosis of intestinal vasculitis is often challenging due to the non-specific clinical and imaging findings. Vasculitides with gastrointestinal (GI) manifestations are rare, but their diagnosis holds immense significance as late or missed recognition can result in high mortality rates. Given the resemblance of radiologic findings with some other entities, GI vasculitis is often overlooked on small bowel studies done using computed tomography/magnetic resonance enterography (CTE/MRE). Hereon, we reviewed radiologic findings of vasculitis with gastrointestinal involvement on CTE and MRE. The variety of findings on MRE/CTE depend upon the size of the involved vessels. Signs of intestinal ischemia, e.g., mural thickening, submucosal edema, mural hyperenhancement, and restricted diffusion on diffusion-weighted imaging, are common in intestinal vasculitis. Involvement of the abdominal aorta and the major visceral arteries is presented as concentric mural thickening, transmural calcification, luminal stenosis, occlusion, aneurysmal changes, and collateral vessels. Such findings can be observed particularly in large- and medium-vessel vasculitis. The presence of extra-intestinal findings, including within the liver, kidneys, or spleen in the form of focal areas of infarction or heterogeneous enhancement due to microvascular involvement, can be another radiologic clue in diagnosis of vasculitis. The link between the clinical/laboratory findings and MRE/CTE abnormalities needs to be corresponded when it comes to the diagnosis of intestinal vasculitis.

Differentiation between Pancreatic Ductal Adenocarcinoma and Normal Pancreatic Tissue for Treatment Response Assessment using Multi-Scale Texture Analysis of CT Images.

Background: Pancreatic ductal adenocarcinoma (PDAC) is the most prevalent type of pancreas cancer with a high mortality rate and its staging is highly dependent on the extent of involvement between the tumor and surrounding vessels, facilitating treatment response assessment in PDAC. Objective: This study aims at detecting and visualizing the tumor region and the surrounding vessels in PDAC CT scan since, despite the tumors in other abdominal organs, clear detection of PDAC is highly difficult. Material and Methods: This retrospective study consists of three stages: 1) a patch-based algorithm for differentiation between tumor region and healthy tissue using multi-scale texture analysis along with L1-SVM (Support Vector Machine) classifier, 2) a voting-based approach, developed on a standard logistic function, to mitigate false detections, and 3) 3D visualization of the tumor and the surrounding vessels using ITK-SNAP software. Results: The results demonstrate that multi-scale texture analysis strikes a balance between recall and precision in tumor and healthy tissue differentiation with an overall accuracy of 0.78±0.12 and a sensitivity of 0.90±0.09 in PDAC. Conclusion: Multi-scale texture analysis using statistical and wavelet-based features along with L1-SVM can be employed to differentiate between healthy and pancreatic tissues. Besides, 3D visualization of the tumor region and surrounding vessels can facilitate the assessment of treatment response in PDAC. However, the 3D visualization software must be further developed for integrating with clinical applications.

Segmentation of pancreatic ductal adenocarcinoma (PDAC) and surrounding vessels in CT images using deep convolutional neural networks and texture descriptors.

Fully automated and volumetric segmentation of critical tumors may play a crucial role in diagnosis and surgical planning. One of the most challenging tumor segmentation tasks is localization of pancreatic ductal adenocarcinoma (PDAC). Exclusive application of conventional methods does not appear promising. Deep learning approaches has achieved great success in the computer aided diagnosis, especially in biomedical image segmentation. This paper introduces a framework based on convolutional neural network (CNN) for segmentation of PDAC mass and surrounding vessels in CT images by incorporating powerful classic features, as well. First, a 3D-CNN architecture is used to localize the pancreas region from the whole CT volume using 3D Local Binary Pattern (LBP) map of the original image. Segmentation of PDAC mass is subsequently performed using 2D attention U-Net and Texture Attention U-Net (TAU-Net). TAU-Net is introduced by fusion of dense Scale-Invariant Feature Transform (SIFT) and LBP descriptors into the attention U-Net. An ensemble model is then used to cumulate the advantages of both networks using a 3D-CNN. In addition, to reduce the effects of imbalanced data, a multi-objective loss function is proposed as a weighted combination of three classic losses including Generalized Dice Loss (GDL), Weighted Pixel-Wise Cross Entropy loss (WPCE) and boundary loss. Due to insufficient sample size for vessel segmentation, we used the above-mentioned pre-trained networks and fine-tuned them. Experimental results show that the proposed method improves the Dice score for PDAC mass segmentation in portal-venous phase by 7.52% compared to state-of-the-art methods in term of DSC. Besides, three dimensional visualization of the tumor and surrounding vessels can facilitate the evaluation of PDAC treatment response.

COVID-19 pneumonia chest radiographic severity score: variability assessment among experienced and in-training radiologists and creation of a multireader composite score database for artificial intelligence algorithm development.

OBJECTIVE: The purpose was to evaluate reader variability between experienced and in-training radiologists of COVID-19 pneumonia severity on chest radiograph (CXR), and to create a multireader database suitable for AI development. METHODS: In this study, CXRs from polymerase chain reaction positive COVID-19 patients were reviewed. Six experienced cardiothoracic radiologists and two residents classified each CXR according to severity. One radiologist performed the classification twice to assess intraobserver variability. Severity classification was assessed using a 4-class system: normal (0), mild (1), moderate (2), and severe (3). A median severity score (Rad Med) for each CXR was determined for the six radiologists for development of a multireader database (XCOMS). Kendal Tau correlation and percentage of disagreement were calculated to assess variability. RESULTS: A total of 397 patients (1208 CXRs) were included (mean age, 60 years SD ± 1), 189 men). Interobserver variability between the radiologists ranges between 0.67 and 0.78. Compared to the Rad Med score, the radiologists show good correlation between 0.79-0.88. Residents show slightly lower interobserver agreement of 0.66 with each other and between 0.69 and 0.71 with experienced radiologists. Intraobserver agreement was high with a correlation coefficient of 0.77. In 220 (18%), 707 (59%), 259 (21%) and 22 (2%) CXRs there was a 0, 1, 2 or 3 class-difference. In 594 (50%) CXRs the median scores of the residents and the radiologists were similar, in 578 (48%) and 36 (3%) CXRs there was a 1 and 2 class-difference. CONCLUSION: Experienced and in-training radiologists demonstrate good inter- and intraobserver agreement in COVID-19 pneumonia severity classification. A higher percentage of disagreement was observed in moderate cases, which may affect training of AI algorithms. ADVANCES IN KNOWLEDGE: Most AI algorithms are trained on data labeled by a single expert. This study shows that for COVID-19 X-ray severity classification there is significant variability and disagreement between radiologist and between residents.