ComBat Harmonization for MRI Radiomics: Impact on Nonbinary Tissue Classification by Machine Learning.

OBJECTIVES: The aims of this study were to determine whether ComBat harmonization improves multiclass radiomics-based tissue classification in technically heterogeneous MRI data sets and to compare the performances of 2 ComBat variants. MATERIALS AND METHODS: One hundred patients who had undergone T1-weighted 3D gradient echo Dixon MRI (2 scanners/vendors; 50 patients each) were retrospectively included. Volumes of interest (2.5 cm 3 ) were placed in 3 disease-free tissues with visually similar appearance on T1 Dixon water images: liver, spleen, and paraspinal muscle. Gray-level histogram (GLH), gray-level co-occurrence matrix (GLCM), gray-level run-length matrix (GLRLM), and gray-level size-zone matrix (GLSZM) radiomic features were extracted. Tissue classification was performed on pooled data from the 2 centers (1) without harmonization, (2) after ComBat harmonization with empirical Bayes estimation (ComBat-B), and (3) after ComBat harmonization without empirical Bayes estimation (ComBat-NB). Linear discriminant analysis with leave-one-out cross-validation was used to distinguish among the 3 tissue types, using all available radiomic features as input. In addition, a multilayer perceptron neural network with a random 70%:30% split into training and test data sets was used for the same task, but separately for each radiomic feature category. RESULTS: Linear discriminant analysis-based mean tissue classification accuracies were 52.3% for unharmonized, 66.3% for ComBat-B harmonized, and 92.7% for ComBat-NB harmonized data. For multilayer perceptron neural network, mean classification accuracies for unharmonized, ComBat-B-harmonized, and ComBat-NB-harmonized test data were as follows: 46.8%, 55.1%, and 57.5% for GLH; 42.0%, 65.3%, and 71.0% for GLCM; 45.3%, 78.3%, and 78.0% for GLRLM; and 48.1%, 81.1%, and 89.4% for GLSZM. Accuracies were significantly higher for both ComBat-B- and ComBat-NB-harmonized data than for unharmonized data for all feature categories (at P = 0.005, respectively). For GLCM ( P = 0.001) and GLSZM ( P = 0.005), ComBat-NB harmonization provided slightly higher accuracies than ComBat-B harmonization. CONCLUSIONS: ComBat harmonization may be useful for multicenter MRI radiomics studies with nonbinary classification tasks. The degree of improvement by ComBat may vary among radiomic feature categories, among classifiers, and among ComBat variants.

Multicenter Phase II Clinical Trial of Gemcitabine and Cisplatin as Neoadjuvant Chemotherapy for Patients With High-Grade Upper Tract Urothelial Carcinoma.

PURPOSE: Neoadjuvant chemotherapy (NAC) has proven survival benefits for patients with invasive urothelial carcinoma of the bladder, yet its role for upper tract urothelial carcinoma (UTUC) remains undefined. We conducted a multicenter, single-arm, phase II trial of NAC with gemcitabine and split-dose cisplatin (GC) for patients with high-risk UTUC before extirpative surgery to evaluate response, survival, and tolerability. METHODS: Eligible patients with defined criteria for high-risk localized UTUC received four cycles of split-dose GC before surgical resection and lymph node dissection. The primary study end point was rate of pathologic response (defined as < ypT2N0). Secondary end points included progression-free survival (PFS), overall survival (OS), and safety and tolerability. RESULTS: Among 57 patients evaluated, 36 (63%) demonstrated pathologic response (95% CI, 49 to 76). A complete pathologic response (ypT0N0) was noted in 11 patients (19%). Fifty-one patients (89%) tolerated at least three complete cycles of split-dose GC, 27 patients (47%) tolerated four complete cycles, and all patients proceeded to surgery. With a median follow up of 3.1 years, 2- and 5-year PFS rates were 89% (95% CI, 81 to 98) and 72% (95% CI, 59 to 87), while 2- and 5-year OS rates were 93% (95% CI, 86 to 100) and 79% (95% CI, 67 to 94), respectively. Pathologic complete and partial responses were associated with improved PFS and OS compared with nonresponders (≥ ypT2N any; 2-year PFS 100% and 95% v 76%, P < .001; 2-year OS 100% and 100% v 80%, P < .001). CONCLUSION: NAC with split-dose GC for high-risk UTUC is a well-tolerated, effective therapy demonstrating evidence of pathologic response that is associated with favorable survival outcomes. Given that these survival outcomes are superior to historical series, these data support the use of NAC as a standard of care for high-risk UTUC, and split-dose GC is a viable option for NAC.

CT Imaging Findings in Patients with Ovarian Cancer and Acute Abdominal Symptoms: Experience at a Tertiary Cancer Center.

PURPOSE: To evaluate computed tomography (CT) findings in patients with ovarian cancer presenting to a comprehensive cancer center's urgent care unit with acute abdominal symptoms. METHODS: This retrospective study included consecutive patients with ovarian cancer who underwent abdominal CT at a comprehensive cancer center's urgent care unit between January 1, 2018, and January 14, 2020, due to acute abdominal symptoms. Two abdominal radiologists reviewed the abdominal CT reports, categorizing imaging findings as follows: (a) no new or acute finding, (b) new or increased bowel or gastric obstruction, (c) new or increased ascites, (d) new or increased peritoneal carcinomatosis, (e) new or increased nonperitoneal metastases, (f) new inflammatory or infectious changes, (g) new or increased hydronephrosis, (h) new or increased biliary dilatation, (i) new vascular complications, or (j) new bowel perforation. RESULTS: A total of 200 patients (mean age, 59 years; range, 22-87) underwent a total of 259 abdominal CT scans, of which 217/259 (83.8%) scans were found to have new or increased findings. A total of 115/259 (44.4%) scans had only one finding while 102/259 (39.4%) scans had 2 or more findings. Altogether, 382 new or increased findings were detected: findings were most commonly related to bowel or gastric obstruction (92/382, 24.1%) with small bowel obstruction being the most common finding (80/382, 20.9%); ascites (78/382, 20.4%); peritoneal carcinomatosis (62/382, 16.2%); and nonperitoneal metastases (62/382, 16.2%). Inflammatory or infectious findings accounted for 30/382 (7.9%) findings. CONCLUSION: Most patients with ovarian cancer presenting with acute abdominal had relevant positive findings on abdominal CT, with small bowel obstruction being the most common finding.

Value of MRI in evaluating urachal carcinoma: A single center retrospective study.

OBJECTIVES: Urachal carcinomas (UrC) are rare non-urothelial bladder neoplasms, however the potential role for MR imaging in UrC has not been well established. Our objective was to assess the value of magnetic resonance imaging (MRI) in primary and recurrent UrC. METHODS AND MATERIALS: This retrospective single-center study included all patients with UrC that underwent MRI between January 2005 and May 2020. Two radiologists reviewed MRIs independently followed by consensus with a third radiologist. For primary UrC, tumor location, size, morphology, invasion of peritoneum and/or local structures other than bladder and concordance between Mayo stage on MRI and pathology were assessed. MRI performed for recurrent UrC evaluated the pattern of recurrence. The reference standard was histopathological analysis. RESULTS: Ninety-six patients with UrC were identified of which 17 were included (9 men and 8 women, median age 50 years [IQR 42-62]). At initial MR staging (n = 10), all primary UrC were located at the bladder dome with median longest axis dimension of 6.0 cm. Most (70%) were mixed solid-and-cystic. Invasion of the peritoneum and/or local structures other than bladder was identified in 30%. Concordance between consensus MRI Mayo stage and final pathologic Mayo stage was 90%. At MR restaging (n = 7), UrC recurrence was most commonly seen at the bladder dome (71%). Overall, MRI showed a sensitivity of 85% and specificity of 50% for detecting recurrent tumor. CONCLUSION: MRI demonstrates value in evaluation of disease extent in primary and recurrent UrC, with high concordance between Mayo stage at MRI and pathology, and in the detection of local recurrences.

Impact of ComBat Harmonization on PET Radiomics-Based Tissue Classification: A Dual-Center PET/MRI and PET/CT Study.

Our purpose was to determine whether ComBat harmonization improves 18F-FDG PET radiomics-based tissue classification in pooled PET/MRI and PET/CT datasets. Methods: Two hundred patients who had undergone 18F-FDG PET/MRI (2 scanners and vendors; 50 patients each) or PET/CT (2 scanners and vendors; 50 patients each) were retrospectively included. Gray-level histogram, gray-level cooccurrence matrix, gray-level run-length matrix, gray-level size-zone matrix, and neighborhood gray-tone difference matrix radiomic features were calculated for volumes of interest in the disease-free liver, spleen, and bone marrow. For individual feature classes and a multiclass radiomic signature, tissue was classified on ComBat-harmonized and unharmonized pooled data, using a multilayer perceptron neural network. Results: Median accuracies in training and validation datasets were 69.5% and 68.3% (harmonized), respectively, versus 59.5% and 58.9% (unharmonized), respectively, for gray-level histogram; 92.1% and 86.1% (harmonized), respectively, versus 53.6% and 50.0% (unharmonized), respectively, for gray-level cooccurrence matrix; 84.8% and 82.8% (harmonized), respectively, versus 62.4% and 58.3% (unharmonized), respectively, for gray-level run-length matrix; 87.6% and 85.6% (harmonized), respectively, versus 56.2% and 52.8% (unharmonized), respectively, for gray-level size-zone matrix; 79.5% and 77.2% (harmonized), respectively, versus 54.8% and 53.9% (unharmonized), respectively, for neighborhood gray-tone difference matrix; and 86.9% and 84.4% (harmonized), respectively, versus 62.9% and 58.3% (unharmonized), respectively, for radiomic signature. Conclusion: ComBat harmonization may be useful for multicenter 18F-FDG PET radiomics studies using pooled PET/MRI and PET/CT data.

When the p Value Doesn't Cut It: The Fragility Index Applied to Randomized Controlled Trials in Colorectal Surgery.

BACKGROUND: The American Statistical Association, among others, has called for the use of statistical methods beyond p ≤ 0.05. The fragility index is a statistical metric defined as the minimum number of patients for whom if an event rather than a nonevent occurred, then the p value would increase to ≥0.05. Previous reviews have demonstrated that many randomized controlled trials have a low fragility index, suggesting they may not be robust. OBJECTIVE: The purpose of this study was to review the fragility indices of randomized controlled trials in colorectal surgery. DATA SOURCES: A PubMed search was performed. STUDY SELECTION: Colorectal surgery randomized controlled trials with a dichotomous primary outcome p ≤ 0.05 and publication between 2016 and 2018 were systematically identified. INTERVENTIONS: All procedural interventions related to colorectal surgery were included. MAIN OUTCOME MEASURES: The main measures were the fragility index and the number of patients lost to follow-up for each trial. The percentage of trials with the number of patients lost to follow-up greater than the fragility index was calculated. RESULTS: In total, 712 abstracts were reviewed, with 90 trials meeting the inclusion criteria. The median fragility index was 3 (interquartile range of 1 to 10). In 51 of the 90 trials (57%), the number of patients lost to follow-up was greater than the fragility index. LIMITATIONS: The fragility index is only one measure of the robustness of a randomized clinical trial. CONCLUSIONS: Most colorectal surgery randomized controlled trials have a low fragility index. In 57% of trials, more patients were lost to follow-up than would be required to change the outcome of the trial from "significant" to "nonsignificant" based on the p value. This emphasizes the importance of assessing the robustness of clinical trials when considering their clinical application, rather than relying solely on the p value. See Video Abstract at http://links.lww.com/DCR/B741.CUANDO EL VALOR-P ES INSUFICIENTE: ÍNDICE DE FRAGILIDAD APLICADO EN ESTUDIOS ALEATORIOS CONTROLADOS EN CIRUGÍA COLORECTAL. ANTECEDENTES: La Sociedad Estadounidense de Estadística, entre otros, ha pedido el uso de métodos estadísticos más allá de p <0,05. El índice de fragilidad es una medida estadística definida como el número de desenlaces que podrían cambiar para revertir, o conseguir, la significación estadística, así el valor p aumentaría a ≥ 0,05. Las revisiones anteriores han demostrado que muchos estudios aleatorios controlados tienen un índice de fragilidad bajo, lo que sugiere que pueden poco sólidos. OBJETIVO: El propósito de la présente investigación fué de revisar los índices de fragilidad de los estudios aleatorios controlados en cirugía colorrectal. FUENTES DE DATOS: PubMed. SELECCIN DE ESTUDIOS: Se identificaron sistemáticamente estudios aleatorios controlados de cirugía colorrectal con un resultado primario dicotómico, valor de p ≤ 0,05 y publicados entre 2016-2018. INTERVENCIONES: Se incluyeron todas aquellas intervenciones con procedimientos relacionados con la cirugía colorrectal. PRINCIPALES MEDIDAS DE RESULTADO: Las principales medidas fueron: el índice de fragilidad y el número de pacientes perdidos durante el seguimiento en cada estudio. Se calculó el el índice de fragilidad en porcentaje de estudios con el mayor número de pacientes perdidos durante el seguimiento mas prolongado. RESULTADOS: En total, se revisaron 712 resúmenes con 90 ensayos que cumplieron con los criterios de inclusión. La mediana del índice de fragilidad fue de 3 (rango intercuartíl de 1 a 10). En 51 de los 90 estudios (57%), el número de pacientes perdidos durante el seguimiento fue mayor que el índice de fragilidad. LIMITACIONES: El índice de fragilidad es solo una medida de la robustez de un estúdio clínico aleatorio. CONCLUSIONES: La mayoría de los estudios aleatorios y controlados en cirugía colorrectal tienen un índice de fragilidad bajo. En el 57% de los estudios, se perdieron más pacientes durante el seguimiento de los que se necesitarían para cambiar el resultado del estudios de grado "significativo" a un grado "no significativo" según el valor-p. Este concepto enfatiza la importancia de evaluar la robustez de los estudios clínicos al considerar su aplicación verdadera aplicación clínica, en lugar de depender únicamente del valor-p. Consulte Video Resumen en http://links.lww.com/DCR/B741. (Traducción-Dr. Xavier Delgadillo).

Automatic Forecasting of Radiology Examination Volume Trends for Optimal Resource Planning and Allocation.

The aim of the study was to evaluate the performance of the Prophet forecasting procedure, part of the Facebook open-source Artificial Intelligence portfolio, for forecasting variations in radiological examination volumes. Daily CT and MRI examination volumes from our institution were extracted from the radiology information system (RIS) database. Data from January 1, 2015, to December 31, 2019, was used for training the Prophet algorithm, and data from January 2020 was used for validation. Algorithm performance was then evaluated prospectively in February and August 2020. Total error and mean error per day were evaluated, and computational time was logged using different Markov chain Monte Carlo (MCMC) samples. Data from 610,570 examinations were used for training; the majority were CTs (82.3%). During retrospective testing, prediction error was reduced from 19 to < 1 per day in CT (total 589 to 17) and from 5 to < 1 per day (total 144 to 27) in MRI by fine-tuning the Prophet procedure. Prospective prediction error in February was 11 per day in CT (9934 predicted, 9667 actual) and 1 per day in MRI (2484 predicted, 2457 actual) and was significantly better than manual weekly predictions (p = 0.001). Inference with MCMC added no substantial improvements while vastly increasing computational time. Prophet accurately models weekly, seasonal, and overall trends paving the way for optimal resource allocation for radiology exam acquisition and interpretation.

Impact of 18F-Fluorodeoxyglucose positron emission tomography on management of cancer of unknown primary: systematic review and meta-analysis.

BACKGROUND: Cancers of unknown primary (CUP) have traditionally been treated empirically, with a dismal prognosis. Compared with standard diagnostic tests, including CT and MRI, imaging with 18F-fluorodeoxyglucose (FDG) PET or PET/CT has shown the capacity to better identify the primary tumour site and detect additional sites of metastasis. However, its clinical impact is not well established. We performed a systematic review and meta-analysis of prior studies to assess the impact of FDG-PET or PET/CT on the management of patients with CUP. MATERIALS AND METHODS: Pubmed and EMBASE databases were searched up to 4th February 2021. Studies that reported the proportion of patients with CUP who experienced a management change after FDG-PET or PET/ computed tomography (CT) were included and the proportions were pooled using the random-effects model. Study quality was assessed using QUADAS-2. Subgroup analysis was conducted to explore heterogeneity. RESULTS: Thirty-eight studies (involving 2795 patients) were included. The pooled proportion of patients with management changes was 35% (95% confidence interval 31%-40%). There was substantial heterogeneity among the studies (Q-test, p < 0.01; I2 = 82%). The specific reason for management change was more commonly detection of the primary site (22% [95% CI 18-28%]) than detection of additional metastatic sites (14% [95% CI 10-19%]). The pooled proportions of patients with management changes were similar among numerous subgroups (range, 32.8%-38.2%). CONCLUSION: FDG-PET or PET/CT had a meaningful impact on the management of patients with CUP. Approximately, a third of patients had their management changed because of FDG-PET or PET/CT results, and this finding was consistent across numerous subgroups.

Minimally invasive therapy for the resolution of a subcapsular hepatic hematoma in a newborn. / Terapia mínimamente invasiva para el manejo de un hematoma subcapsular hepático en un recién nacido.

OBJECTIVE: To describe an innovative alternative to exploratory laparotomy in a newborn with a sub capsular hepatic hematoma secondary to umbilical vein catheterization. CLINICAL CASE: A preterm baby with a history of hyaline membrane disease, pulmonary hypertension, and large patent ductus arteriosus, requiring mechanical ventilation and the use of vasoactive drugs. Umbilical catheters were inserted and through an abdomen X-ray, we observed their proper position. The patient evolved with greater requirements of vasoactive drugs, abdominal wall pallor, and abdominal distention. Abdominal ultrasound showed a subcapsular hepatic hematoma, with no signs of active bleeding, so expectant management was decided. The patient required increased vasoactive drugs and presented a decrease in hematocrit. New ultrasound showed a larger subcapsular hematoma, abundant perihe patic fluid, and the intraparenchymal position of the umbilical catheter was confirmed. Endovascular embolization was performed through the umbilical catheter with Gelita®, achieving occlusion of the capsular path. Posterior ultrasound showed a reduction of the hematoma. CONCLUSIONS: The use of embolization through angiography is not commonly used in pediatric emergencies. It is a procedure with fewer comorbidities and complications than exploratory laparotomy, therefore it should be considered as first-line therapy in patients like the one presented above. The limitation for its routine performance is the lack of available angiography operating room and trained interventional radio logy team.

Multidisciplinary Recommendations Regarding Post-Vaccine Adenopathy and Radiologic Imaging: Radiology Scientific Expert Panel.

Vaccination-associated adenopathy is a frequent imaging finding after administration of COVID-19 vaccines that may lead to a diagnostic conundrum in patients with manifest or suspected cancer, in whom it may be indistinguishable from malignant nodal involvement. To help the medical community address this concern in the absence of studies and evidence-based guidelines, this special report offers recommendations developed by a multidisciplinary panel of experts from three of the leading tertiary care cancer centers in the United States. According to these recommendations, some routine imaging examinations, such as those for screening, should be scheduled before or at least 6 weeks after the final vaccination dose to allow for any reactive adenopathy to resolve. However, there should be no delay of other clinically indicated imaging (eg, for acute symptoms, short-interval treatment monitoring, urgent treatment planning or complications) due to prior vaccination. The vaccine should be administered on the side contralateral to the primary or suspected cancer, and both doses should be administered in the same arm. Vaccination information-date(s) administered, injection site(s), laterality, and type of vaccine-should be included in every preimaging patient questionnaire, and this information should be made readily available to interpreting radiologists. Clear and effective communication between patients, radiologists, referring physician teams, and the general public should be considered of the highest priority when managing adenopathy in the setting of COVID-19 vaccination.

Estimating the impact of treatment and imaging modalities on 5-year net survival of 11 cancers in 200 countries: a simulation-based analysis.

BACKGROUND: Accurate survival estimates are important for cancer control planning. Although observed survival estimates are unavailable for many countries, where they are available, wide variations are reported. Understanding the impact of specific treatment and imaging modalities can help decision makers to effectively allocate resources to improve cancer survival in their local context. METHODS: We developed a microsimulation model of stage-specific cancer survival in 200 countries and territories for 11 cancers (oesophagus, stomach, colon, rectum, anus, liver, pancreas, lung, breast, cervix uteri, and prostate) comprising 60% of global diagnosed cancer cases. The model accounts for country-specific availability of treatment (chemotherapy, surgery, radiotherapy, and targeted therapy) and imaging modalities (ultrasound, x-ray, CT, MRI, PET, single-photon emission CT), as well as quality of care. We calibrated the model to reported survival estimates from CONCORD-3 (which reports global trends in cancer survival in 2000-14). We estimated 5-year net survival for diagnosed cancers in each country or territory and estimated potential survival gains from increasing the availability of individual treatment and imaging modalities, and more comprehensive packages of scale-up of these interventions. We report the mean and 95% uncertainty intervals (UIs) for all outcomes, calculated as the 2·5 and 97·5 percentiles of the simulation results. FINDINGS: The estimated global 5-year net survival for all 11 cancers combined is 42·6% (95% uncertainty interval 40·3-44·3), with survival in high-income countries being an average of 12 times (range 4-17) higher than that in low-income countries. Expanding availability of surgery or radiotherapy or improving quality of care would yield the largest survival gains in low-income (2·5-3·4 percentage point increase in survival) and lower-middle-income countries (2·4-6·1 percentage point increase), whereas upper-middle-income and high-income countries are more likely to benefit from improved availability of targeted therapy (0·7 percentage point increase for upper-middle income and 0·4 percentage point increase for high income). Investing in medical imaging will also be necessary to achieve substantial survival gains, with traditional modalities estimated to provide the largest gains in low-income settings, while MRI and PET would yield the largest gains in higher-income countries. Simultaneous expansion of treatment, imaging, and quality of care could improve 5-year net survival by more than ten times in low-income countries (3·8% [95% UI 0·5-9·2] to 45·2% [40·2-52·1]) and could more than double 5-year net survival in lower-middle-income countries (20·1% [7·2-31·7] to 47·1% [42·8-50·8]). INTERPRETATION: Scaling up both treatment and imaging availability could yield synergistic survival gains for patients with cancer. Expanding traditional modalities in lower-income settings might be a feasible pathway to improve survival before scaling up more modern technologies. FUNDING: Harvard T H Chan School of Public Health.

The role and contribution of treatment and imaging modalities in global cervical cancer management: survival estimates from a simulation-based analysis.

BACKGROUND: Cervical cancer is the fourth most common cancer among women worldwide, causing more than 300 000 deaths globally each year. In addition to screening and prevention, effective cancer treatment is needed to reduce cervical cancer mortality. We discuss the role of imaging in cervical cancer management and estimate the potential survival effect of scaling up imaging in several different contexts. METHODS: Using a previously developed microsimulation model of global cancer survival, we estimated stage-specific cervical cancer 5-year net survival in 200 countries and territories. We evaluated the potential survival effect of scaling up treatment (chemotherapy, surgery, radiotherapy, and targeted therapy), and imaging modalities (ultrasound, x-ray, CT, MRI, PET, and single photon emission CT [SPECT]) to the mean level of high-income countries, both individually and in combination. FINDINGS: We estimate global cervical cancer 5-year net survival as 42·1% (95% uncertainty interval [UI] 33·8-48·5). Among individual imaging modalities, expanding MRI would yield the largest 5-year survival gains globally (data are absolute percentage point increase in survival 0·6, 95% UI 0·1-2·1), scaling up ultrasound would yield the largest gains in low-income countries (0·5, 0·0-3·7), expanding CT and x-ray would have the greatest effect in Latin America (0·8, 0·0-3·4) and Oceania (0·4, 0·0-3·2), and expanding PET would yield the largest gains in high-income countries (0·2, 0·0-0·8). Scaling up SPECT did not show major changes in any region. Among individual treatment modalities, scaling up radiotherapy would yield the largest absolute percentage point gains in low-income countries (5·2, 0·3-13·5), and expanding surgery would have the largest effect in lower-middle-income countries (7·4, 0·3-21·1) and upper-middle-income countries (0·8, 0·0-2·9). Estimated survival gains in high-income countries were very modest. However, the gains from expanding any single treatment or imaging modality individually were small across all income levels and geographical settings. Scaling up all treatment modalities could improve global 5-year net survival to 52·4% (95% UI 44·6-62·0). In addition to expanding treatment, improving quality of care could raise survival to 57·5% (51·2-63·5), and the cumulative effect of scaling up all imaging modalities together with expanded treatment and quality of care could improve 5-year net survival for cervical cancer to 62·5% (57·7-67·8). INTERPRETATION: Comprehensive scale-up of treatment, imaging, and quality of care could substantially improve global cervical cancer 5-year net survival, with quality of care and imaging improvements each contributing about 25% of the total potential gains. These findings suggest that a narrow focus on the availability of treatment modalities could forgo substantial survival gains. Investments in imaging equipment, personnel, and quality of care efforts will also be needed to successfully scale up cervical cancer treatment worldwide. FUNDING: Harvard T H Chan School of Public Health and National Cancer Institute.

Constraints on Lorentz Invariance Violation from HAWC Observations of Gamma Rays above 100 TeV.

Because of the high energies and long distances to the sources, astrophysical observations provide a unique opportunity to test possible signatures of Lorentz invariance violation (LIV). Superluminal LIV enables the decay of photons at high energy. The high altitude water Cherenkov (HAWC) observatory is among the most sensitive gamma-ray instruments currently operating above 10 TeV. HAWC finds evidence of 100 TeV photon emission from at least four astrophysical sources. These observations exclude, for the strongest of the limits set, the LIV energy scale to 2.2×10^{31} eV, over 1800 times the Planck energy and an improvement of 1 to 2 orders of magnitude over previous limits.

Utility of Routine Preoperative 18F-Fluorodeoxyglucose Positron Emission Tomography/Computerized Tomography in Identifying Pathological Lymph Node Metastases at Radical Cystectomy.

PURPOSE: We determined the diagnostic performance of 18F-FDG (fluorodeoxyglucose) positron emission tomography/computerized tomography for detecting nodal metastases in patients with muscle invasive urothelial bladder cancer before radical cystectomy. MATERIALS AND METHODS: Preoperative 18F-FDG positron emission tomography/computerized tomography scans (208) were retrospectively reviewed. Scans were routinely performed in 185 patients with muscle invasive urothelial bladder cancer between August 2012 and February 2017, all of whom underwent radical cystectomy and pelvic lymph node dissection. Analyses were stratified by clinical node involvement and chemotherapy status. The diagnostic performance of 18F-FDG positron emission tomography/computerized tomography was assessed according to sensitivity, specificity, positive predictive value and negative predictive value. RESULTS: Lymph node metastases at time of pelvic lymph node dissection were present in 21.8% of those without suspicious nodes on computerized tomography (clinically node negative) and 52.6% of those with suspicious nodes on computerized tomography (clinically node positive). Median metastatic focus size was 5 mm. In clinically node negative cases 18F-FDG positron emission tomography/computerized tomography rarely detected nodal metastases (sensitivity 7% to 23%). In clinically node positive cases negative 18F-FDG positron emission tomography/computerized tomography was useful in ruling out lymph node metastases (sensitivity 92% to 100%). This study was limited by its mixed population and focus on pelvic nodal metastases only. CONCLUSIONS: 18F-FDG positron emission tomography/computerized tomography appears to be most useful for better characterization of enlarged nodes identified by computerized tomography. Routine preoperative 18F-FDG positron emission tomography/computerized tomography has limited utility in clinically node negative cases.