Multicentre validation of CT grey-level co-occurrence matrix features for overall survival in primary oesophageal adenocarcinoma.

BACKGROUND: Personalising management of primary oesophageal adenocarcinoma requires better risk stratification. Lack of independent validation of proposed imaging biomarkers has hampered clinical translation. We aimed to prospectively validate previously identified prognostic grey-level co-occurrence matrix (GLCM) CT features for 3-year overall survival. METHODS: Following ethical approval, clinical and contrast-enhanced CT data were acquired from participants from five institutions. Data from three institutions were used for training and two for testing. Survival classifiers were modelled on prespecified variables ('Clinical' model: age, clinical T-stage, clinical N-stage; 'ClinVol' model: clinical features + CT tumour volume; 'ClinRad' model: ClinVol features + GLCM_Correlation and GLCM_Contrast). To reflect current clinical practice, baseline stage was also modelled as a univariate predictor ('Stage'). Discrimination was assessed by area under the receiver operating curve (AUC) analysis; calibration by Brier scores; and clinical relevance by thresholding risk scores to achieve 90% sensitivity for 3-year mortality. RESULTS: A total of 162 participants were included (144 male; median 67 years [IQR 59, 72]; training, 95 participants; testing, 67 participants). Median survival was 998 days [IQR 486, 1594]. The ClinRad model yielded the greatest test discrimination (AUC, 0.68 [95% CI 0.54, 0.81]) that outperformed Stage (ΔAUC, 0.12 [95% CI 0.01, 0.23]; p = .04). The Clinical and ClinVol models yielded comparable test discrimination (AUC, 0.66 [95% CI 0.51, 0.80] vs. 0.65 [95% CI 0.50, 0.79]; p > .05). Test sensitivity of 90% was achieved by ClinRad and Stage models only. CONCLUSIONS: Compared to Stage, multivariable models of prespecified clinical and radiomic variables yielded improved prediction of 3-year overall survival. CLINICAL RELEVANCE STATEMENT: Previously identified radiomic features are prognostic but may not substantially improve risk stratification on their own. KEY POINTS: • Better risk stratification is needed in primary oesophageal cancer to personalise management. • Previously identified CT features-GLCM_Correlation and GLCM_Contrast-contain incremental prognostic information to age and clinical stage. • Compared to staging, multivariable clinicoradiomic models improve discrimination of 3-year overall survival.

Automated Triaging of Adult Chest Radiographs with Deep Artificial Neural Networks.

Purpose To develop and test an artificial intelligence (AI) system, based on deep convolutional neural networks (CNNs), for automated real-time triaging of adult chest radiographs on the basis of the urgency of imaging appearances. Materials and Methods An AI system was developed by using 470 388 fully anonymized institutional adult chest radiographs acquired from 2007 to 2017. The free-text radiology reports were preprocessed by using an in-house natural language processing (NLP) system modeling radiologic language. The NLP system analyzed the free-text report to prioritize each radiograph as critical, urgent, nonurgent, or normal. An AI system for computer vision using an ensemble of two deep CNNs was then trained by using labeled radiographs to predict the clinical priority from radiologic appearances only. The system's performance in radiograph prioritization was tested in a simulation by using an independent set of 15 887 radiographs. Prediction performance was assessed with the area under the receiver operating characteristic curve; sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were also determined. Nonparametric testing of the improvement in time to final report was determined at a nominal significance level of 5%. Results Normal chest radiographs were detected by our AI system with a sensitivity of 71%, specificity of 95%, PPV of 73%, and NPV of 94%. The average reporting delay was reduced from 11.2 to 2.7 days for critical imaging findings (P < .001) and from 7.6 to 4.1 days for urgent imaging findings (P < .001) in the simulation compared with historical data. Conclusion Automated real-time triaging of adult chest radiographs with use of an artificial intelligence system is feasible, with clinically acceptable performance. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Auffermann in this issue.

Developing and validating a simple urethra surrogate model to facilitate dosimetric analysis to predict genitourinary toxicity.

Purpose: The urethra is a critical structure in prostate radiotherapy planning; however, it is impossible to visualise on CT. We developed a surrogate urethra model (SUM) for CT-only planning workflow and tested its geometric and dosimetric performance against the MRI-delineated urethra (MDU). Methods: The SUM was compared against 34 different MDUs (within the treatment PTV) in patients treated with 36.25Gy (PTV)/40Gy (CTV) in 5 fractions as part of the PACE-B trial. To assess the surrogate's geometric performance, the Dice similarity coefficient (DSC), Hausdorff distance (HD), mean distance to agreement (MDTA) and the percentage of MDU outside the surrogate (UOS) were calculated. To evaluate the dosimetric performance, a paired t-test was used to calculate the mean of differences between the MDU and SUM for the D99, D98, D50, D2 and D1. The D(n) is the dose (Gy) to n% of the urethra. Results: The median results showed low agreement on DSC (0.32; IQR 0.21-0.41), but low distance to agreement, as would be expected for a small structure (HD 8.4mm (IQR 7.1-10.1mm), MDTA 2.4mm (IQR, 2.2mm-3.2mm)). The UOS was 30% (IQR, 18-54%), indicating nearly a third of the urethra lay outside of the surrogate. However, when comparing urethral dose between the MDU and SUM, the mean of differences for D99, D98 and D95 were 0.12Gy (p=0.57), 0.09Gy (p=0.61), and 0.11Gy (p=0.46) respectively. The mean of differences between the D50, D2 and D1 were 0.08Gy (p=0.04), 0.09Gy (p=0.02) and 0.1Gy (p=0.01) respectively, indicating good dosimetric agreement between MDU and SUM. Conclusion: While there were geometric differences between the MDU and SUM, there was no clinically significant difference between urethral dose-volume parameters. This surrogate model could be validated in a larger cohort and then used to estimate the urethral dose on CT planning scans in those without an MRI planning scan or urinary catheter.

Association of dynamic contrast-enhanced MRI and 18F-Fluorodeoxyglucose PET/CT parameters with neoadjuvant therapy response and survival in esophagogastric cancer.

INTRODUCTION: Better predictive markers are needed to deliver individualized care for patients with primary esophagogastric cancer. This exploratory study aimed to assess whether pre-treatment imaging parameters from dynamic contrast-enhanced MRI and 18F-fluorodeoxyglucose (18F-FDG) PET/CT are associated with response to neoadjuvant therapy or outcome. MATERIALS AND METHODS: Following ethical approval and informed consent, prospective participants underwent dynamic contrast-enhanced MRI and 18F-FDG PET/CT prior to neoadjuvant chemotherapy/chemoradiotherapy ± surgery. Vascular dynamic contrast-enhanced MRI and metabolic 18F-FDG PET parameters were compared by tumor characteristics using Mann Whitney U test and with pathological response (Mandard tumor regression grade), recurrence-free and overall survival using logistic regression modelling, adjusting for predefined clinical variables. RESULTS: 39 of 47 recruited participants (30 males; median age 65 years, IQR: 54, 72 years) were included in the final analysis. The tumor vascular-metabolic ratio was higher in patients remaining node positive following neoadjuvant therapy (median tumor peak enhancement/SUVmax ratio: 0.052 vs. 0.023, p = 0.02). In multivariable analysis adjusted for age, gender, pre-treatment tumor and nodal stage, peak enhancement (highest gadolinium concentration value prior to contrast washout) was associated with pathological tumor regression grade. The odds of response decreased by 5% for each 0.01 unit increase (OR 0.95; 95% CI: 0.90, 1.00, p = 0.04). No 18F-FDG PET/CT parameters were predictive of pathological tumor response. No relationships between pre-treatment imaging and survival were identified. CONCLUSION: Pre-treatment esophagogastric tumor vascular and metabolic parameters may provide additional information in assessing response to neoadjuvant therapy.

State-of-the-art imaging in oesophago-gastric cancer.

Radiological investigations are essential in the management of oesophageal and gastro-oesophageal junction cancers. The current multimodal combination of CT, 18F-fluorodeoxyglucose positron emission tomography combined with CT (PET/CT) and endoscopic ultrasound (EUS) has limitations, which hinders the prognostic and predictive information that can be used to guide optimum treatment decisions. Therefore, the development of improved imaging techniques is vital to improve patient management. This review describes the current evidence for state-of-the-art imaging techniques in oesophago-gastric cancer including high resolution MRI, diffusion-weighted MRI, dynamic contrast-enhanced MRI, whole-body MRI, perfusion CT, novel PET tracers, and integrated PET/MRI. These novel imaging techniques may help clinicians improve the diagnosis, staging, treatment planning, and response assessment of oesophago-gastric cancer.

Bladder paragangliomas: a pictorial review.

Bladder paragangliomas (bPGL) are rare neuroendocrine tumors arising from the sympathetic paraganglia present in the bladder wall. Bladder PGLs are typically submucosal or intramural but when subserosal may not be readily visible at cystoscopy. The average size at presentation is 3.9 cm (range 1.0-9.1 cm). When small, bPGL are usually spherical, well-marginated and homogeneous. Larger bPGL are typically more complex with peri- and intra-tumoral neovascularity and central necrosis. On ultrasound, increased color Doppler signal is typical. The increased soft tissue resolution of MRI enables localization of bPGL within the bladder wall more accurately than CT. Restricted diffusion and avid contrast enhancement help differentiate small bPGLs from leiomyomas, which have similar appearances on ultrasound and CT. Nuclear medicine techniques identify bPGLs and their metastases with high specificity, 68Ga-DOTATATE PET/CT having largely replaced 123I-mIBG SPECT/CT as the first line functional investigation. Imaging is essential to aid surgical planning, as endoscopic resection is often not possible or incomplete due to tumor location. For patients with advanced disease, 68Ga-DOTATATE PET/CT and 123I-mIBG SPECT/CT assess suitability for peptide receptor radionuclide therapy. Up to 63% of bPGL patients have a germline mutation, most commonly in the SDHB subunit gene, increasing their risk of developing pheochromocytomas and further paragangliomas; lifelong annual biochemical and periodic imaging screening from skull base to pelvis is therefore recommended.

Initial experience in staging primary oesophageal/gastro-oesophageal cancer with 18F-FDG PET/MRI.

BACKGROUND: 18F-fluorodeoxyglucose positron emission tomography/magnetic resonance imaging (18F-FDG PET/MRI) may improve cancer staging by combining sensitive cancer detection with high-contrast resolution and detail. We compared the diagnostic performance of 18F-FDG PET/MRI to 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) for staging oesophageal/gastro-oesophageal cancer. Following ethical approval and informed consent, participants with newly diagnosed primary oesophageal/gastro-oesophageal cancer were enrolled. Exclusions included prior/concurrent malignancy. Following 324 ± 28 MBq 18F-FDG administration and 60-min uptake, PET/CT was performed, immediately followed by integrated PET/MRI from skull base to mid-thigh. PET/CT was interpreted by two dual-accredited nuclear medicine physicians and PET/MRI by a dual-accredited nuclear medicine physician/radiologist and cancer radiologist in consensus. Per-participant staging was compared with the tumour board consensus staging using the McNemar test, with statistical significance at 5%. RESULTS: Out of 26 participants, 22 (20 males; mean ± SD age 68.8 ± 8.7 years) completed 18F-FDG PET/CT and PET/MRI. Compared to the tumour board, the primary tumour was staged concordantly in 55% (12/22) with PET/MRI and 36% (8/22) with PET/CT; the nodal stage was concordant in 45% (10/22) with PET/MRI and 50% (11/22) with PET/CT. There was no statistical difference in PET/CT and PET/MRI staging performance (p > 0.05, for T and N staging). The staging of distant metastases was concordant with the tumour board in 95% (21/22) with both PET/MRI and PET/CT. Of participants with distant metastatic disease, PET/MRI detected additional metastases in 30% (3/10). CONCLUSION: In this preliminary study, compared to 18F-FDG PET/CT, 18F-FDG PET/MRI showed non-significant higher concordance with T-staging, but no difference with N or M-staging. Additional metastases detected by 18F-FDG PET/MRI may be of additive clinical value.

Multiparametric Ultrasound of Nonpalpable Focal Testicular Lesions.

Indeterminate nonpalpable focal testicular lesions have emerged as a clinical problem with the increasing use of scrotal ultrasound, particularly in the context of infertility. Conventional morphological ultrasound and color Doppler have been unreliable at differentiating benign from malignant lesions. Multiparametric ultrasound (mpUS) comprises real-time elastography and contrast-enhanced ultrasound as adjunctive tools, and is ready for use in most state-of-the-art ultrasound systems. Initial experience with mpUS from selected specialist centers shows promise for lesion characterization, and potential for affecting management and improving outcomes. This article provides a summary of the existing literature on testicular mpUS, and outlines the clinical context from a urological and histopathological perspective.

Lesser sac herniation: a rare cause of acute abdomen and bowel perforation.

Lesser sac herniation is a rare phenomenon, where the bowel protrudes through the epiploic foramen into the lesser sac. We describe the case of a 55-year-old male who presented with acute abdominal pain and in whose case the subtle findings of lesser sac herniation were missed during CT scan reporting. Re-review of the images after the patient's condition deteriorated found evidence of herniation, and re-scanning at that point demonstrated progression of the herniation, with bowel obstruction and perforation. The findings of lesser sac herniation complicated by basculetype caecal volvulus were confirmed during laparotomy. The patient underwent right hemicolectomy with primary ileocolic anastomosis.