Validation of a Resectability Scoring System for Prediction of Pancreatic Adenocarcinoma Surgical Outcomes.

BACKGROUND: The most used pancreatic cancer (PC) resectability criteria are descriptive in nature or based solely on dichotomous degree of involvement (< 180° or > 180°) of vessels, which allows for a high degree of subjectivity and inconsistency. METHODS: Radiographic measurements of the circumferential degree and length of tumor contact with major peripancreatic vessels were retrospectively obtained from pre-treatment multi-detector computed tomography (MDCT) images from PC patients treated between 2001 and 2015 at two large academic institutions. Arterial and venous scores were calculated for each patient, then tested for a correlation with tumor resection and R0 resection. RESULTS: The analysis included 466 patients. Arterial and venous scores were highly predictive of resection and R0 resection in both the training (n = 294) and validation (n = 172) cohorts. A recursive partitioning tree based on arterial and venous score cutoffs developed with the training cohort was able to stratify patients of the validation cohort into discrete groups with distinct resectability probabilities. A refined recursive partitioning tree composed of three resectability groups was generated, with probabilities of resection and R0 resection of respectively 94 and 73% for group A, 61 and 35% for group B, and 4 and 2% for group C. This resectability scoring system (RSS) was highly prognostic, predicting median overall survival times of 27, 18.9, and 13.5 months respectively for patients in RSS groups A, B, and C (p < 0.001). CONCLUSIONS: The proposed RSS was highly predictive of resection, R0 resection, and prognosis for patients with PC when tested against an external dataset.

Color Doppler Imaging of Vascular Abnormalities of the Uterus.

ABSTRACT: Many uterine abnormalities present clinically with bleeding encompassing a broad spectrum of patients from postmenopausal spotting to life-threatening hemorrhage. Color and spectral Doppler imaging of the pelvis is often the first crucial investigation used to quickly establish the correct etiology of the uterine bleeding and guide clinical decision making and patient management.

Evaluation of early sonographic predictors of gangrenous cholecystitis: mucosal discontinuity and echogenic pericholecystic fat.

PURPOSE: To identify early sonographic features of gangrenous cholecystitis. MATERIALS AND METHODS: 101 patients with acute cholecystitis and a pre-operative sonogram were retrospectively reviewed by three radiologists in this IRB-approved and HIPAA-compliant study. Imaging data were correlated with histologic findings and compared using the Fisher's exact test or Student t test with p < 0.05 to determine statistical significance. RESULTS: Forty-eight patients had gangrenous cholecystitis and 53 had non-gangrenous acute cholecystitis. Patients with gangrenous cholecystitis tended to be older (67 ± 17 vs 48 ± 18 years; p = 0.0001), male (ratio of male:female 2:1 vs 0.6:1; p = 0.005), tachycardic (60% vs 28%; p = 0.001), and diabetic (25% vs 8%; p = 0.001). Median time between pre-operative sonogram and surgery was 1 day. On imaging, patients with gangrenous cholecystitis were more likely to have echogenic pericholecystic fat (p = 0.001), mucosal discontinuity (p = 0.010), and frank perforation (p = 0.004), while no statistically significant differences were seen in the presence of sloughed mucosa (p = 0.104), pericholecystic fluid (p = 0.523) or wall striations (p = 0.839). In patients with gangrenous cholecystitis and echogenic pericholecystic fat, a smaller subset had concurrent mucosal discontinuity (57%), and a smaller subset of those had concurrent frank perforation (58%). The positive likelihood ratios for gangrenous cholecystitis with echogenic fat and mucosal discontinuity were 4.6 (95% confidence interval 1.9-11.3) and 14.4 (2.0-106), respectively. CONCLUSION: Echogenic pericholecystic fat and mucosal discontinuity are early sonographic findings that may help identify gangrenous cholecystitis prior to late findings of frank perforation.

Quantitative image features from radiomic biopsy differentiate oncocytoma from chromophobe renal cell carcinoma.

Purpose: To differentiate oncocytoma and chromophobe renal cell carcinoma (RCC) using radiomics features computed from spherical samples of image regions of interest, "radiomic biopsies" (RBs). Approach: In a retrospective cohort study of 102 CT cases [68 males (67%), 34 females (33%); mean age ± SD, 63 ± 12 years ], we pathology-confirmed 42 oncocytomas (41%) and 60 chromophobes (59%). A board-certified radiologist performed two RB rounds. From each RB round, we computed radiomics features and compared the performance of a random forest and AdaBoost binary classifier trained from the features. To control for overfitting, we performed 10 rounds of 70% to 30% train-test splits with feature-selection, cross-validation, and hyperparameter-optimization on each split. We evaluated the performance with test ROC AUC. We tested models on data from the other RB round and compared with the same round testing with the DeLong test. We clustered important features for each round and measured a bootstrapped adjusted Rand index agreement. Results: Our best classifiers achieved an average AUC of 0.71 ± 0.024 . We found no evidence of an effect for RB round ( p = 1 ). We also found no evidence for a decrease in model performance when tested on the other RB round ( p = 0.85 ). Feature clustering produced seven clusters in each RB round with high agreement ( Rand index = 0.981 ± 0.002 , p < 0.00001 ). Conclusions: A consistent radiomic signature can be derived from RBs and could help distinguish oncocytoma and chromophobe RCC.

Non-invasive assessment of cirrhosis using multiphasic dual-energy CT iodine maps: correlation with model for end-stage liver disease score.

PURPOSE: To determine whether multiphasic dual-energy (DE) CT iodine quantitation correlates with the severity of chronic liver disease. METHODS: We retrospectively included 40 cirrhotic and 28 non-cirrhotic patients who underwent a multiphasic liver protocol DECT. All three phases (arterial, portal venous (PVP), and equilibrium) were performed in DE mode. Iodine (I) values (mg I/ml) were obtained by placing regions of interest in the liver, aorta, common hepatic artery, and portal vein (PV). Iodine slopes (λ) were calculated as follows: (Iequilibrium-Iarterial)/time and (Iequilibrium-IPVP)/time. Spearman correlations between λ and MELD scores were evaluated, and the area under the curve of the receiver operating characteristic (AUROC) was calculated to distinguish cirrhotic and non-cirrhotic patients. RESULTS: Cirrhotic and non-cirrhotic patients had significantly different λequilibrium-arterial [IQR] for the caudate (λ = 2.08 [1.39-2.98] vs 1.46 [0.76-1.93], P = 0.007), left (λ = 2.05 [1.50-2.76] vs 1.51 [0.59-1.90], P = 0.002) and right lobes (λ = 1.72 [1.12-2.50] vs 1.13 [0.41-0.43], P = 0.003) and for the PV (λ = 3.15 [2.20-5.00] vs 2.29 [0.85-2.71], P = 0.001). λequilibrium-PVP were significantly different for the right (λ = 0.11 [- 0.45-1.03] vs - 0.44 [- 0.83-0.12], P = 0.045) and left lobe (λ = 0.30 [- 0.25-0.98] vs - 0.10 [- 0.35-0.24], P = 0.001). Significant positive correlations were found between MELD scores and λequilibrium-arterial for the caudate lobe (ρ = 0.34, P = 0.004) and λequilibrium-PVP for the caudate (ρ = 0.26, P = 0.028) and right lobe (ρ = 0.33, P = 0.007). AUROC in distinguishing cirrhotic and non-cirrhotic patients were 0.72 (P = 0.002), 0.71 (P = 0.003), and 0.75 (P = 0.001) using λequilibrium-arterial for the left lobe, right lobe, and PV, respectively. The λequilibrium-PVP AUROC of the right lobe was 0.73 (P = 0.001). CONCLUSION: Multiphasic DECT iodine quantitation over time is significantly different between cirrhotic and non-cirrhotic patients, correlates with the MELD score, and it could potentially serve as a non-invasive measure of cirrhosis and disease severity with acceptable diagnostic accuracy.

Hyperechoic Periappendiceal Fat: Evaluation of Criteria for Improving Specificity in the Sonographic Diagnosis of Appendicitis in Pediatric Patients.

OBJECTIVES: To test the hypothesis that abutting and encasing types of hyperechoic periappendiceal fat are specific sonographic indicators of appendicitis in pediatric patients, including individuals with maximum outer diameters (MODs) of 6 to 8 mm in whom diagnosis by the MOD alone is known to be equivocal. METHODS: Appendiceal sonograms of 271 consecutive pediatric patients were retrospectively evaluated for hyperechoic periappendiceal fat (globular, ≥1.0 cm; categorized as type 0, none; type 1, "abutting," encompassing <180° of the appendiceal circumference; or type 2, "encasing," encompassing 180° or more of the appendiceal circumference) and the MOD. Histopathologic and medical records constituted reference standards. Statistical methods included the binomial distribution, logistic regression, a receiver operating characteristic analysis, and the exact McNemar test. RESULTS: All patients with hyperechoic fat and 105 of 107 patients with appendicitis had MODs of 6 mm or greater. The MOD and fat types 1 and 2 each were significantly associated with appendicitis in the univariable regression. The MOD and fat type 1 were independently associated with appendicitis in multivariable regression (odds ratio, 24.97; P = .034; and odds ratio, 5.35; P < .001, respectively). Specificities of an MOD of 6 to 8 mm and an MOD of 6 mm or greater alone were 89.0% (95% confidence interval, 83.2%-93.4%); these increased to 100.0% each (95% confidence interval, 97.8%-100.0%; P < .001) when combined with fat types 1, 2, and either 1 or 2 as diagnostic criteria, with positive predictive values of 100.0%. CONCLUSIONS: Types 1 and 2 periappendiceal fat are specific indicators of appendicitis, and both improve specificity compared to the MOD. Importantly, they add specificity in diagnosing appendicitis in patients with diagnostically equivocal MODs of 6 to 8 mm.

The Borderline-Size Appendix: Grayscale, Color Doppler, and Spectral Doppler Findings That Improve Specificity for the Sonographic Diagnosis of Acute Appendicitis.

Diagnostic criteria for acute appendicitis using graded compression sonography have been well established based on the maximum outer diameter (MOD) of the appendix, with MOD values of <6 mm nearly always indicating normal appendices and MOD values of >8 mm nearly always indicating appendicitis. However, the "borderline-size" appendix, meaning one whose MOD lies between these ranges (ie, an appendix with MOD of 6-8 mm), presents a diagnostic dilemma because appendices in this size range are neither clearly normal nor abnormal when diagnosis is based on the MOD alone; accordingly, such borderline MOD values are diagnostically equivocal, and sonographic diagnosis must rely on sonographic findings other than the MOD. The goal of this review was to examine the additional sonographic findings that can add specificity and help enable an accurate diagnosis to be made in patients with borderline-size appendices.

Cost-effectiveness of dual-energy CT versus multiphasic single-energy CT and MRI for characterization of incidental indeterminate renal lesions.

PURPOSE: To evaluate the cost-effectiveness of DECT versus multiphasic CT and MRI for characterizing small incidentally detected indeterminate renal lesions using a Markov Monte Carlo decision-analytic model. BACKGROUND: Incidental renal lesions are commonly encountered due to the increasing utilization of medical imaging and the increasing prevalence of renal lesions with age. Currently recommended imaging modalities to further characterize incidental indeterminate renal lesions have some inherent drawbacks. Single-phase DECT may overcome these limitations, but its cost-effectiveness remains uncertain. MATERIALS AND METHODS: A decision-analytic (Markov) model was constructed to estimate life expectancy and lifetime costs for otherwise healthy 64-year-old patients with small (≤ 4 cm) incidentally detected, indeterminate renal lesions on routine imaging (e.g., ultrasound or single-phase CT). Three strategies for evaluating renal lesions for enhancement were compared: multiphase SECT (e.g., true unenhanced and nephrographic phase), multiphasic MRI, and single-phase DECT (nephrographic phase in dual-energy mode). The model incorporated modality-specific diagnostic test performance, incidence, and prevalence of incidental renal cell carcinomas (RCCs), effectiveness, costs, and health outcomes. An incremental cost-effectiveness analysis was performed to identify strategy preference at willingness-to-pay (WTP) thresholds of $50,000 and $100,000 per quality-adjusted life-year (QALY) gained. Deterministic and probabilistic sensitivity analysis were performed. RESULTS: In the base case analysis, expected mean costs per patient undergoing characterization of incidental renal lesions were $2567 for single-phase DECT, $3290 for multiphasic CT, and $3751 for multiphasic MRI. Associated quality-adjusted life-years were the highest for single-phase DECT at 0.962, for multiphasic MRI it was 0.940, and was the lowest for multiphasic CT at 0.925. Because of lower associated costs and higher effectiveness, the single-phase DECT strategy dominated the other two strategies. CONCLUSIONS: Single-phase DECT is potentially more cost-effective than multiphasic SECT and MRI for evaluating small incidentally detected indeterminate renal lesions.

Does measurement of the hepatic artery velocity improve the sonographic diagnosis of cholangitis?

OBJECTIVE: To determine the frequency of elevated peak systolic proper hepatic artery velocity (HAV) in patients with acute cholangitis and to determine the diagnostic performance of this metric relative to existing criteria. METHODS: Between 9/2016 and 11/2017, 107 patients clinically suspected to have cholangitis were referred for an abdominal ultrasound. Of these, 56 patients had HAV measurements and were included in the final analysis. Clinical and imaging features, including HAV, HAV resistive index (RI), portal vein velocity (PVV), biliary dilation, and presence of an obstructive etiology were extracted. The diagnostic performance of HAV was compared to the existing available clinical criteria (Charcot's triad and 2018 Tokyo Guidelines). Elevated HAV was defined as HAV > 100 cm/s. Presence of cholangitis was determined by the discharge summary following medical workup and admission or observation. RESULTS: 32% had cholangitis while 68% did not. Average HAV for patients with cholangitis was 152 ± 54 cm/s versus 91 ± 44 cm/s for those without (p < 0.0001; t test). The HAV was elevated in 83% of patients with cholangitis. When considered in isolation, an elevated HAV had a high negative predictive value (90%), was more accurate (77%; 95% confidence interval 64-87%) than Charcot's triad (73%; 60-83%), and had similar accuracy compared to 2018 Tokyo Guidelines (79%; 66-88%). Substitution of conventional imaging criteria with elevated HAV in the 2018 Tokyo Guidelines yielded the highest overall accuracy of 84% (72-92%). CONCLUSION: HAV is elevated in the majority of patients with cholangitis. Substitution of an elevated HAV for conventional sonographic criteria is more accurate than existing clinical criteria in identifying patients with cholangitis.

Predicting Pancreatic Cancer Resectability and Outcomes Based on an Objective Quantitative Scoring System.

OBJECTIVE: To quantitatively assess the probability of tumor resection based on measurements of tumor contact with the major peripancreatic vessels. METHODS: This is a retrospective cohort study of pancreatic cancer patients treated between January 2001 and December 2015 in a single academic comprehensive cancer center. Radiographic measurements of the circumferential degree and length of solid tumor contact with major peripancreatic vessels were obtained from diagnostic pancreatic protocol computed tomography images and tested for correlation with tumor resection and margin status. RESULTS: Of 294 patients analyzed, 113 (38%) were resected, with 71 (63%) with negative margins. Based on the individual measurements of vascular involvement, a resectability scoring system (RSS) was created. The RSS correlated strongly with resection (P < 0.0001) and R0 resection (P < 0.0001) probabilities. Moreover, the RSS correlated with overall survival (P < 0.0001) and metastasis-free survival (P < 0.0001), being able to substratify resectable (P = 0.022) and unresectable patients (P = 0.014) into subgroups with different prognosis based on RSS scores. CONCLUSIONS: Based on a comprehensive and systematic quantitative approach, we developed a scoring system that demonstrated excellent accuracy to predict tumor resection, surgical margin status, and prognosis.

Performance of Hepatic Artery Velocity in Evaluation of Causes of Markedly Elevated Liver Tests.

The purpose of this study was to assess the utility of peak systolic proper hepatic artery velocity (HAV) in differentiating causes of severely elevated liver function tests. HAV, hepatic artery resistive index and portal vein velocity of 41 patients with severely elevated liver function tests were evaluated. In 19 patients (46%), the causes were structural (e.g., cholecystitis, cholangitis), whereas in 22 patients (54%) the causes were non-structural (e.g., rhabdomyolysis, drug-induced liver injury). The average HAV for structural causes was 138 ± 68cm/s, and for non-structural causes, 65 ± 29cm/s (p < 0.0001). An HAV >100cm/s was correlated with structural causes (p = 0.0001). With respect to diagnostic performance, this threshold was 79% sensitive and 86% specific, with a high positive likelihood ratio (5.8) and low negative likelihood ratio (0.24). The resistive index and portal vein velocity were not statistically different. In patients with severely elevated liver function tests, an HAV >100cm/s can help distinguish structural from non-structural causes, which may guide management while awaiting definitive laboratory tests.

Bowel obstruction complicated by ischemia: analysis of CT findings.

PURPOSE: To analyze CT signs of bowel ischemia in patients with surgical bowel obstruction, and thereby improve CT diagnosis in this common clinical scenario. Surgical and histopathological findings were used as the reference standard. METHODS: We retrospectively analyzed CT findings in patients brought to surgery for bowel obstruction over 13 years. Etiology of obstruction (adhesion, hernia, etc.) was recorded. Specific CT features of acute mesenteric ischemia (AMI) were analyzed, including bowel wall thickening, mucosal hypoenhancement, and others. RESULTS: 173 cases were eligible for analysis. 21% of cases were positive for bowel ischemia. Volvulus, internal hernia, and closed-loop obstructions showed ischemia rates of 60%, 43%, and 43%; ischemia rate in obstruction from simple adhesion was 21%. Patients with bowel obstruction related to malignancy were never ischemic. Sensitivities and specificities for CT features predicting ischemia were calculated, with wall thickening, hypoenhancement, and pneumatosis showing high specificity for ischemia (86%-100%). CONCLUSION: Wall thickening, hypoenhancement, and pneumatosis are highly specific CT signs of ischemia in the setting of obstruction. None of the evaluated CT signs were found to be highly sensitive. Overall frequency of ischemia in surgical bowel obstruction is 21%, and 2-3 times that for complex obstructions (volvulus, closed loop, etc.). Obstructions related to malignancy virtually never become ischemic.

Central echogenic areas in thyroid nodules: Diagnostic performance in prediction of papillary cancer.

PURPOSE: To determine the diagnostic performance of the "central echogenic area" sonographic finding in differentiating papillary carcinomas from benign nodules and to how this finding may be used to improve fine needle aspiration(FNA) technique/utilization. MATERIALS AND METHODS: We retrospectively analyzed ultrasound guided FNAs of thyroid nodules between 1 and 3 cm for central echogenic areas. 92 patients (evenly distributed benign vs papillary carcinoma) were evaluated by a blinded reader for areas of non-shadowing homogenously echogenic centers within the nodules and correlated with FNA proven pathologic diagnosis. A selection of nodules with the central echogenic area finding were selected for further slide review to establish a pathologic basis for the finding. RESULTS: Diagnostic performance of the "central echogenic area" feature in papillary thyroid cancers was 52.2% sensitive and 91.3% specific for papillary thyroid carcinoma with a PPV of 85.7% and NPV of 65.6%. There was a significant correlation with a p < 0.01 between the central echogenic area finding and papillary carcinoma. On pathologic slide review, nodules with central echogenic areas consistently demonstrated a central scar with conglomerate fibrosis and very few viable cells. CONCLUSION: Despite its relatively low sensitivity, the central echogenic area finding is highly specific for papillary carcinoma of the thyroid and can be a useful sonographic finding in decisions regarding FNA. Additionally, due to the paucity of cells and high density of conglomerate fibrosis, central echogenic areas should be avoided during FNA to decrease the chance of an inadequate sample collection.

Diagnostic Performance of Margin Features in Thyroid Nodules in Prediction of Malignancy.

OBJECTIVE: The purpose of this study was to evaluate thyroid nodule margins for specific morphologic features and determine the diagnostic performance of these features in differentiating papillary carcinoma from benign thyroid nodules. MATERIALS AND METHODS: Nodules measuring 1-3 cm in largest diameter that had been evaluated with high-resolution ultrasound (12-18 MHz) and ultrasound-guided biopsy with definitive pathologic diagnosis were analyzed. Three blinded board-certified readers evaluated high-resolution images of each nodule for jagged edges, lobulated borders, and curved borders along their margins. Reader interpretations were correlated with the pathologic diagnosis to determine the diagnostic performance of each feature. A board-certified pathologist analyzed 10 randomly selected nodules with jagged edges by slide review to evaluate for structural correlation with the imaging finding. RESULTS: The diagnostic performance of jagged edges in papillary carcinoma of the thyroid was 67.4% sensitive and 78.3% specific (odds ratio, 7.44; p < 0.001) for malignancy. Jagged edges correlated with infiltrative variant expansion at slide review. Lobulated borders had sensitivity of 76.1% and specificity of 60.9% for papillary carcinoma (odds ratio, 4.95; p = 0.001) for malignancy. Curved borders were not a significant predictor of papillary carcinoma. CONCLUSION: Jagged edges and lobulated borders of thyroid nodule margins are statistically significant predictors of papillary carcinoma of the thyroid. Jagged edges correlate with infiltrative-type expansion and may be useful predictors of more aggressive papillary carcinomas.

Sonography of the Cecum: Gateway to the Right Lower Quadrant.

Sonography of the cecum has come of age largely as a consequence of the successful evolution of appendiceal sonography as a useful tool in the evaluation of patients with right lower-quadrant pain. At some medical centers, graded-compression sonography (GCS) has become the initial imaging study of choice in the assessment of these individuals. The cecum serves as a helpful anatomic landmark for localization of the appendix in these examinations-providing a sonographic starting point in the search for the appendix. During GCS, primary pathology within the cecum itself can become evident, including a variety of processes, such as infectious, inflammatory, or neoplastic disorders, whose presentations commonly mimic that of appendicitis. The accurate diagnosis of cecal abnormalities and their differentiation from acute appendicitis play valuable roles in the management of affected patients because the options for further workup and subsequent treatment vary greatly according to the diagnosis at hand. Additionally, the compressed cecum often becomes an acoustic window into the right lower quadrant, revealing pathology apart from the appendix within the right iliac fossa. The purpose of this pictorial essay is to highlight the importance and value of performing a careful evaluation of the cecum during GCS of patients with suspected appendicitis and to review the differential diagnosis and imaging findings of primary cecal abnormalities whose clinical presentations can mimic that of acute appendicitis.

The utility of hepatic artery velocity in diagnosing patients with acute cholecystitis.

PURPOSE: To test the diagnostic performance of elevated peak systolic hepatic arterial velocity (HAv) in the diagnosis of acute cholecystitis. METHODS: 229 patients with an ultrasound (US) performed for right upper quadrant (RUQ) pain were retrospectively reviewed. 35 had cholecystectomy within 10 days of ultrasound and were included as test subjects. 47 had normal US and serology and were included as controls. Each test patient US was reviewed for the presence of gallstones, gallbladder distention, sludge, echogenic pericholecystic fat, pericholecystic fluid, gallbladder wall thickening, gallbladder wall hyperemia, and reported sonographic Murphy sign. Demographic, clinical, and hepatic artery parameters at time of original imaging were recorded. Acute cholecystitis at pathology was the primary outcome variable. RESULTS: 21 patients had acute cholecystitis and 14 had chronic cholecystitis by pathology. For patients who went to cholecystectomy, HAv ≥100 cm/s to diagnose acute cholecystitis was more accurate (69%) than the original radiology report (63%), the presence of gallstones (51%), and sonographic Murphy sign (50%). Statistically significant predictors of acute cholecystitis included HAv ≥100 cm/s (p = 0.008), older age (p = 0.012), and elevated WBC (p = 0.002), while gallstones (p = 0.077), hepatic artery resistive index (HARI) (p = 0.199), gallbladder distension (p = 0.252), sludge (p = 0.147), echogenic fat (p = 0.184), pericholecystic fluid (p = 0.357), wall thickening (p = 0.434), hyperemia (p = 0.999), and sonographic Murphy sign (p = 0.765) were not significantly correlated with acute cholecystitis compared to chronic cholecystitis. CONCLUSION: HAv ≥100 cm/s is a useful objective parameter that may improve the performance of US in the diagnosis of acute cholecystitis.

Duodenal invasion by pancreatic adenocarcinoma: MDCT diagnosis of an aggressive imaging phenotype and its clinical implications.

Despite advances in oncologic and imaging technology, pancreatic ductal adenocarcinoma remains a highly deadly disease. The only curative option, pancreaticoduodenectomy or pancreatectomy, carries a significant morbidity. Current imaging plays a role in pre-operative staging to determine the probability of achieve disease-free margins. However, a small but not insignificant number of pancreatic cancers have a relatively higher aggressive biology, despite being resectable based on traditional criteria. Recently, imaging biomarkers that serve as a surrogate for tumors with such aggressive phenotype have been described. These include duodenal invasion and extrapancreatic perineural invasion. This review will focus on the former highlighting the summary of literature supporting duodenal invasion as a surrogate for aggressive disease as well as review its MDCT imaging features.

Extrapancreatic perineural invasion in pancreatic adenocarcinoma.

Pancreatic ductal adenocarcinoma continues to be a highly lethal disease, despite advances in modern medicine. Curative surgical options continue to carry significant morbidity and offer little improvement in overall 5-year survival. Currently, imaging plays an essential role in the pre-operative evaluation of patients who are undergoing evaluation for resection. However, some pancreatic cancers have particularly aggressive biology, despite appearing resectable by conventional imaging criteria. Imaging biomarkers that serve as surrogates for tumors with such aggressive phenotype have been recently described, namely duodenal invasion and extrapancreatic perineural invasion. In this pictorial review, we will summarize key concepts of extrapancreatic perineural invasion, describe its association with a poor prognosis, and highlight the role of imaging in its detection.

Intra-Individual Comparison between 2-D Shear Wave Elastography (GE System) and Virtual Touch Tissue Quantification (Siemens System) in Grading Liver Fibrosis.

Ultrasound-based shear wave elastography (SWE) has recently gained substantial attention for non-invasive assessment of liver fibrosis. The purpose of this study was to perform an intra-individual comparison between 2-D shear wave elastography (2-D-SWE with a GE system) and Virtual Touch Tissue Quantification (VTTQ with a Siemens system) to assess whether these can be used interchangeably to grade fibrosis. Ninety-three patients (51 men, 42 women; mean age, 54 y) with liver disease of various etiologies (hepatitis B virus = 47, hepatitis C virus = 22; alcohol = 6, non-alcoholic steatohepatitis = 5, other = 13) were included. Using published system-specific shear wave speed cutoff values, liver fibrosis was classified into clinically non-significant (F0/F1) and significant (≥F2) fibrosis. Results indicated that intra-modality repeatability was excellent for both techniques (GE 2-D-SWE: intra-class correlation coefficient = 0.89 [0.84-0.93]; VTTQ: intra-class correlation coefficient = 0.90 [0.86-0.93]). Intra-modality classification agreement for fibrosis grading was good to excellent (GE 2-D-SWE: κ = 0.65, VTTQ: κ = 0.82). However, inter-modality agreement for fibrosis grading was only fair (κ = 0.31) using published system-specific shear wave speed cutoff values of fibrosis. In conclusion, although both GE 2-D-SWE and Siemens VTTQ exhibit good to excellent intra-modality repeatability, inter-modality agreement is only fair, suggesting that these should not be used interchangeably.