Main Pancreatic Duct to Parenchymal Thickness Ratio at Preoperative Imaging is Associated with Overall Survival in Upfront Resected Pancreatic Cancer.

BACKGROUND: Pancreatic cancer induces parenchymal atrophy and duct dilation. The aim of this study was to evaluate whether these radiologic modifications are associated with outcomes. METHODS: Upfront pancreaticoduodenectomy patients with available preoperative contrast enhanced CT scan imaging were retrospectively analyzed. Thickness of the pancreas, size of the main pancreatic duct (MPD), and distance of the tumor from the ampulla were assessed. A training cohort was selected, including short- (3-12 months following surgery) and long-term (≥ 36 months) survivors. Identified survival determinants were validated in the overall cohort. RESULTS: Two-hundred-sixteen patients were analyzed. In the training cohort (N = 118), 68 patients (57.6%) were in the short-term and 50 (42.4%) in the long-term survival group. The short-term survival group had significantly higher CA 19-9 levels (p = 0.027), larger tumors (32.6 ± 12.1 mm vs. 26.5 ± 11.6 mm, p = 0.007), poorer differentiation (p = 0.003), higher rate of R < 1 mm resections (54% vs. 32%, p = 0.008), and reduced receipt of adjuvant chemotherapy (p = 0.020). The MPD-to-pancreatic thickness ratio was significantly lower in the short-term survivors (3.6 ± 6.2 vs. 8.2 ± 12.0, p = 0.016). In the entire cohort, an MPD-to-pancreatic thickness ratio ≥ 3.5 was associated with improved OS [median 33.0 months IQR (19.7-48.1) versus 17 months IQR (14.8-19.2), p = 0.004], and confirmed by a Cox-proportional hazards model independently associated with OS (HR = 0.58; p = 0.009), together with tumor size (HR = 1.02; p =0.012), R1/R2 status (HR = 1.53; p = 0.029), and receipt of adjuvant treatment (HR = 0.61; p = 0.021). CONCLUSIONS: High MPD-to-pancreatic thickness ratio was associated with improved long-term survival in pancreaticoduodenectomy for cancer. Whether these features are related to tumor chronicity, indolent biology, or local growth over metastasis remains to be determined.

Low-keV and Low-kVp CT for Positive Oral Contrast Media in Patients with Cancer: A Randomized Clinical Trial.

Background Substantial gain in the attenuation of iodine on low-kVp and dual-energy CT processed low-keV virtual monochromatic images provides an opportunity for customization of positive oral contrast media administration. Purpose To perform an intrapatient comparison of bowel labeling, opacification, and taste preference with iodinated oral contrast medium (ICM) in standard (sICM) and 25%-reduced (rICM) concentrations at low tube voltage (100 kVp) or on low-energy (50-70 keV) virtual monochromatic images compared with barium-based oral contrast medium (BCM) at 120 kVp. Materials and Methods In this prospective clinical trial, 200 adults (97 men, 103 women; mean age, 63 years ± 13 [standard deviation]) who weighed less than 113 kg and who were undergoing oncologic surveillance (from April 2017 to July 2018) and who had previously undergone 120-kVp abdominopelvic CT with BCM randomly received sICM (7.2 g iodine) or rICM (5.4 g iodine) and underwent 100-kVp CT or dual-energy CT (80/140 kVp) scans to be in one of four groups (n = 50 each): sICM/100 kVp, rICM/100 kVp, sICM/dual-energy CT, and rICM/dual-energy CT. Qualitative analysis was performed for image quality (with a five-point scale), extent of bowel labeling, and homogeneity of opacification (with a four-point scale). Intraluminal attenuation of opacified small bowel was measured. A post-CT patient survey was performed to indicate contrast medium preference, taste of ICM (with a five-point scale), and adverse effects. Data were analyzed with analogs of analysis of variance. Results All CT studies were of diagnostic image quality (3.4 ± 0.3), with no difference in the degree of bowel opacification between sICM and rICM (P > .05). Compared with BCM/120 kVp (282 HU ± 73), mean attenuation was 78% higher with sICM/100 kVp (459 HU ± 282) and 26%-121% higher at sICM/50-65 keV (50 keV = 626 HU ± 285; 65 keV = 356 HU ± 171). With rICM, attenuation was 46% higher for 100 kVp (385 HU ± 215) and 19%-108% higher for 50-65 keV (50 keV = 567 HU ± 270; 65 keV = 325 HU ± 156) compared with BCM (P < .05). A total of 171 of 200 study participants preferred ICM to BCM, with no taste differences between sICM and rICM (3.9 ± 0.6). Fifteen participants had diarrhea with BCM, but none had diarrhea with ICM. Conclusion A 25%-reduced concentration of iodinated oral contrast medium resulted in acceptable bowel labeling while yielding substantially higher luminal attenuation at low-kVp and low-keV CT examinations with improved preference in patients undergoing treatment for cancer. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Laghi in this issue.

Virtual Monochromatic Dual-Energy Aortoiliac CT Angiography With Reduced Iodine Dose: A Prospective Randomized Study.

OBJECTIVE: The purpose of this study was to assess the feasibility of performing abdominopelvic aortoiliac CT angiography (CTA) with 16.0 g of iodine contrast medium acquired with low-energy (40 and 50 keV) virtual monochromatic (VMC) images with rapid-kilovoltage-switching dual-energy CT. SUBJECTS AND METHODS: A total of 52 adults with abdominal aortoiliac aneurysm and prior 120-kVp single-energy CTA (SECTA) with 33 g iodine (standard dose) underwent follow-up dual-energy CTA (DECTA) with a 52% reduced iodine dose. Subjects were randomly assigned to a contrast medium protocol for DECTA examinations: one group (n = 26) received 16.2 g (270 mg I/mL) and the other (n = 26) received 16.0 g (320 mg I/mL). Two readers independently assessed SECTA and VMC DECTA datasets for image quality using a 5-point scale. Aortoiliac intravascular attenuation was measured, and ANOVA was used to compare measurements between VMC DECTA and SECTA images. In a subset of patients with DECTA after endovascular aortic repair, endoleak detection was evaluated on VMC images. Volume CT dose index, dose-length product, and size-specific dose estimate were compared between DECTA and SECTA. RESULTS: All DECTA examinations (n = 52) were rated diagnostic with image quality scores comparable to those of 120-kVp single-energy CTA (40 keV, 4.2-4.4; 50 keV, 4.6-4.8; SECTA, 4.4-4.5). Intravascular attenuation was uniform in all reduced-iodine DECTA examinations and was significantly higher on 40- and 50-keV images than on standard-iodine-dose SECTA images (720 ± 125 HU and 482 ± 82 HU vs 303 ± 65 HU) (p < 0.01). There was no difference in intravascular attenuation between the 16.2-g and the 16.0-g doses (p = 0.82). Sensitivity and specificity for endoleak detection were 78.9-94.7% and 100%. Total dose-length product was lower for DECTA (788 ± 166 mGy · cm) than for SECTA (1114 ± 468 mGy · cm). CONCLUSION: Low-energy VMC DECTA images (40 and 50 keV) acquired with two contrast protocols at approximately 50% reduced iodine dose (16.0 and 16.2 g) provide adequate intravascular attenuation and diagnostic quality for aortoiliac evaluation.

Long-term Risk of Pancreatic Malignancy in Patients With Branch Duct Intraductal Papillary Mucinous Neoplasm in a Referral Center.

BACKGROUND & AIMS: Little is known about the development of branch duct intraductal papillary mucinous neoplasms (BD-IPMNs). We evaluated long-term outcomes of a large cohort of patients with BD-IPMNs to determine risk of malignancy and define a subset of low-risk BD-IPMNs. METHODS: We performed a retrospective analysis of data from 577 patients with suspected or presumed BD-IPMN under surveillance at the Massachusetts General Hospital. Patients underwent cross-sectional imaging analysis at 3 months or later after their initial diagnosis. The diagnosis of BD-IPMN was based on the presence of unilocular or multilocular cysts of the pancreas and a non-dilated main pancreatic duct (<5 mm). We collected demographic, clinical, and pathology data. Cysts were characterized at the time of diagnosis and during the follow-up period. Follow-up duration was time between initial cyst diagnosis and date of last visit or death for patients without development of pancreatic cancer, date of surgery for patients with histologically confirmed malignancy, or date of first discovery of malignancy by imaging analysis for patients with unresectable tumors or who underwent neoadjuvant treatment before surgery. The primary outcome was risk of malignancy, with a focus on patients followed for 5 years or more, compared with that of the US population, based on standardized incidence ratio. RESULTS: Of the 577 patients studied, 479 (83%) were asymptomatic at diagnosis and 363 (63%) underwent endoscopic ultrasound at least once. The median follow-up time was 82 months (range, 6-329 months) for the entire study cohort; 363 patients (63%) underwent surveillance for more than 5 years, and 121 (21%) for more than 10 years. Malignancies (high-grade dysplasia or invasive neoplasm) developed after 5 years in 20 of 363 patients (5.5%), and invasive cancer developed in 16 of 363 patients (4.4%). The standardized incidence ratio for patients with BD-IPMNs without worrisome features of malignancy at 5 years was 18.8 (95% confidence interval, 9.7-32.8; P < .001). One hundred and eight patients had cysts ≤1.5 cm for more than 5 years of follow-up; only 1 of these patients (0.9%) developed a distinct ductal adenocarcinoma. By contrast, among the 255 patients with cysts >1.5 cm, 19 (7.5%) developed malignancy (P = .01). CONCLUSIONS: In a retrospective analysis of patients with BD-IPMNs under surveillance, their overall risk of malignancy, almost 8%, lasted for 10 years or more, supporting continued surveillance after 5 years. Cysts that remain ≤1.5 cm for more than 5 years might be considered low-risk for progression to malignancy.

Dual-energy CT: a phantom comparison of different platforms for abdominal imaging.

OBJECTIVES: Evaluation of imaging performance across dual-energy CT (DECT) platforms, including dual-layer CT (DLCT), rapid-kVp-switching CT (KVSCT) and dual-source CT (DSCT). METHODS: A semi-anthropomorphic abdomen phantom was imaged on these DECT systems. Scans were repeated three times for CTDIvol levels of 10 mGy, 20 mGy, 30 mGy and different fat-simulating extension rings. Over the available range of virtual-monoenergetic images (VMI), noise as well as quantitative accuracy of hounsfield units (HU) and iodine concentrations were evaluated. RESULTS: For all VMI levels, HU values could be determined with high accuracy compared to theoretical values. For KVSCT and DSCT, a noise increase was observed towards lower VMI levels. A patient-size dependent increase in the uncertainty of quantitative iodine concentrations is observed for all platforms. For a medium patient size the iodine concentration root-mean-square deviation at 20 mGy is 0.17 mg/ml (DLCT), 0.30 mg/ml (KVSCT) and 0.77mg/ml (DSCT). CONCLUSION: Noticeable performance differences are observed between investigated DECT systems. Iodine concentrations and VMI HUs are accurately determined across all DECT systems. KVSCT and DLCT deliver slightly more accurate iodine concentration values than DSCT for investigated scenarios. In DLCT, low-noise and high-image contrast at low VMI levels may help to increase diagnostic information in abdominal CT. KEY POINTS: • Current dual-energy CT platforms provide accurate, reliable quantitative information. • Dual-energy CT cross-platform evaluation revealed noticeable performance differences between different systems. • Dual-layer CT offers constant noise levels over the complete energy range.

Advances in Pancreatic CT Imaging.

OBJECTIVE: The purpose of this article is to discuss the advances in CT acquisition and image postprocessing as they apply to imaging the pancreas and to conceptualize the role of radiogenomics and machine learning in pancreatic imaging. CONCLUSION: CT is the preferred imaging modality for assessment of pancreatic diseases. Recent advances in CT (dual-energy CT, CT perfusion, CT volumetry, and radiogenomics) and emerging computational algorithms (machine learning) have the potential to further increase the value of CT in pancreatic imaging.

Characterization of Portal Vein Thrombosis (Neoplastic Versus Bland) on CT Images Using Software-Based Texture Analysis and Thrombus Density (Hounsfield Units).

OBJECTIVE: The purpose of this study was to investigate the role of CT texture analysis and thrombus density (measured in Hounsfield units) in distinguishing between neoplastic and bland portal vein thrombosis (PVT) on portal venous phase CT. MATERIALS AND METHODS: In this retrospective study, 117 contrast-enhanced CT studies of 109 patients were included for characterization of PVT. Assessment of PVT was performed by estimation of CT textural features using CT texture analysis software and measurement of attenuation values. For CT texture analysis, filtered and unfiltered images were assessed to quantify heterogeneity using a set of predefined histogram-based texture parameters. The Mann-Whitney U test and binary logistic regression were applied for statistical significance. ROC curves were used to identify accuracy and optimal cutoff values. RESULTS: Of the 117 CT studies, 63 neoplastic thrombi and 54 bland thrombi were identified on the images. The two most discriminative CT texture analysis parameters to differentiate neoplastic from bland thrombus were mean value of positive pixels (without filtration, p < 0.001) and entropy (with fine filtration, p < 0.001). Mean thrombus density values could also reliably distinguish neoplastic (81.39 HU) and bland (32.88 HU) thrombi (p < 0.001). The AUCs were 0.97 for mean value of positive pixels (p < 0.001), 0.93 for entropy (p < 0.001), 0.99 for the model combining mean value of positive pixels and entropy (p < 0.001), 0.91 for thrombus density (p < 0.001), and 0.61 for the radiologist's subjective evaluation (p = 0.037). The optimal cutoffs values were 56.9 for mean value of positive pixels, 4.50 for entropy, and 54.0 HU for thrombus density. CONCLUSION: CT texture analysis and CT attenuation values allow reliable differentiation between neoplastic and bland thrombi on a single portal venous phase CT examination.

Material Separation Using Dual-Energy CT: Current and Emerging Applications.

Dual-energy (DE) computed tomography (CT) offers the opportunity to generate material-specific images on the basis of the atomic number Z and the unique mass attenuation coefficient of a particular material at different x-ray energies. Material-specific images provide qualitative and quantitative information about tissue composition and contrast media distribution. The most significant contribution of DE CT-based material characterization comes from the capability to assess iodine distribution through the creation of an image that exclusively shows iodine. These iodine-specific images increase tissue contrast and amplify subtle differences in attenuation between normal and abnormal tissues, improving lesion detection and characterization in the abdomen. In addition, DE CT enables computational removal of iodine influence from a CT image, generating virtual noncontrast images. Several additional materials, including calcium, fat, and uric acid, can be separated, permitting imaging assessment of metabolic imbalances, elemental deficiencies, and abnormal deposition of materials within tissues. The ability to obtain material-specific images from a single, contrast-enhanced CT acquisition can complement the anatomic knowledge with functional information, and may be used to reduce the radiation dose by decreasing the number of phases in a multiphasic CT examination. DE CT also enables generation of energy-specific and virtual monochromatic images. Clinical applications of DE CT leverage both material-specific images and virtual monochromatic images to expand the current role of CT and overcome several limitations of single-energy CT. (©)RSNA, 2016.

Iterative Reconstruction Techniques in Abdominopelvic CT: Technical Concepts and Clinical Implementation.

OBJECTIVE: This article discusses the clinical challenge of low-radiation-dose examinations, the commonly used approaches for dose optimization, and their effect on image quality. We emphasize practical aspects of the different iterative reconstruction techniques, along with their benefits, pitfalls, and clinical implementation. CONCLUSION: The widespread use of CT has raised concerns about potential radiation risks, motivating diverse strategies to reduce the radiation dose associated with CT. CT manufacturers have developed alternative reconstruction algorithms intended to improve image quality on dose-optimized CT studies, mainly through noise and artifact reduction. Iterative reconstruction techniques take unique approaches to noise reduction and provide distinct strength levels or settings.

A quantitative comparison of noise reduction across five commercial (hybrid and model-based) iterative reconstruction techniques: an anthropomorphic phantom study.

OBJECTIVE. The objective of our study was to compare the performance of three hybrid iterative reconstruction techniques (IRTs) (ASiR, iDose4, SAFIRE) and their respective strengths for image noise reduction on low-dose CT examinations using filtered back projection (FBP) as the standard reference. Also, we compared the performance of these three hybrid IRTs with two model-based IRTs (Veo and IMR) for image noise reduction on low-dose examinations. MATERIALS AND METHODS. An anthropomorphic abdomen phantom was scanned at 100 and 120 kVp and different tube current-exposure time products (25-100 mAs) on three CT systems (for ASiR and Veo, Discovery CT750 HD; for iDose4 and IMR, Brilliance iCT; and for SAFIRE, Somatom Definition Flash). Images were reconstructed using FBP and using IRTs at various strengths. Nine noise measurements (mean ROI size, 423 mm(2)) on extracolonic fat for the different strengths of IRTs were recorded and compared with FBP using ANOVA. Radiation dose, which was measured as the volume CT dose index and dose-length product, was also compared. RESULTS. There were no significant differences in radiation dose and image noise among the scanners when FBP was used (p > 0.05). Gradual image noise reduction was observed with each increasing increment of hybrid IRT strength, with a maximum noise suppression of approximately 50% (48.2-53.9%). Similar noise reduction was achieved on the scanners by applying specific hybrid IRT strengths. Maximum noise reduction was higher on model-based IRTs (68.3-81.1%) than hybrid IRTs (48.2-53.9%) (p < 0.05). CONCLUSION. When constant scanning parameters are used, radiation dose and image noise on FBP are similar for CT scanners made by different manufacturers. Significant image noise reduction is achieved on low-dose CT examinations rendered with IRTs. The image noise on various scanners can be matched by applying specific hybrid IRT strengths. Model-based IRTs attain substantially higher noise reduction than hybrid IRTs irrespective of the radiation dose.

Advances in CT imaging for urolithiasis.

Urolithiasis is a common disease with increasing prevalence worldwide and a lifetime-estimated recurrence risk of over 50%. Imaging plays a critical role in the initial diagnosis, follow-up and urological management of urinary tract stone disease. Unenhanced helical computed tomography (CT) is highly sensitive (>95%) and specific (>96%) in the diagnosis of urolithiasis and is the imaging investigation of choice for the initial assessment of patients with suspected urolithiasis. The emergence of multi-detector CT (MDCT) and technological innovations in CT such as dual-energy CT (DECT) has widened the scope of MDCT in the stone disease management from initial diagnosis to encompass treatment planning and monitoring of treatment success. DECT has been shown to enhance pre-treatment characterization of stone composition in comparison with conventional MDCT and is being increasingly used. Although CT-related radiation dose exposure remains a valid concern, the use of low-dose MDCT protocols and integration of newer iterative reconstruction algorithms into routine CT practice has resulted in a substantial decrease in ionizing radiation exposure. In this review article, our intent is to discuss the role of MDCT in the diagnosis and post-treatment evaluation of urolithiasis and review the impact of emerging CT technologies such as dual energy in clinical practice.

Fetal Head and Neck Imaging.

Prenatal MRI plays an essential role in the evaluation of the head and neck. This article overviews technical considerations and both isolated and syndromic anomalies of the fetal calvarium, globes and orbits, ears, maxilla, mandible, and neck.

Optimal Abdominal CT Image Quality in Non-Lean Patients: Customization of CM Injection Protocols and Low-Energy Acquisitions.

We compared the image quality of abdominopelvic single-energy CT with 100 kVp (SECT-100 kVp) and dual-energy CT with 65 keV (DECT-65 keV) obtained with customized injection protocols to standard abdominopelvic CT scans (SECT-120 kVp) with fixed volumes of contrast media (CM). We retrospectively included 91 patients (mean age, 60.7 ± 15.8 years) with SECT-100 kVp and 83 (mean age, 60.3 ± 11.7 years) patients with DECT-65 keV in portovenous phase. Total body weight-based customized injection protocols were generated by a software using the following formula: patient weight (kg) × 0.40/contrast concentration (mgI/mL) × 1000. Patients had a prior abdominopelvic SECT-120 kVp with fixed injection. Iopamidol-370 was administered for all examinations. Quantitative and qualitative image quality comparisons were made between customized and fixed injection protocols. Compared to SECT-120 kVp, customized injection yielded a significant reduction in CM volume (mean difference = 9-12 mL; p ≤ 0.001) and injection rate (mean differences = 0.2-0.4 mL/s; p ≤ 0.001) in all weight categories. Improvements in attenuation, noise, signal-to-noise and contrast-to-noise ratios were observed for both SECT-100 kVp and DECT-65 keV compared to SECT-120 kVp in all weight categories (e.g., pancreas DECT-65 keV, 1.2-attenuation-fold increase vs. SECT-120 kVp; p < 0.001). Qualitative scores were ≥4 in 172 cases (98.8.4%) with customized injections and in all cases with fixed injections (100%). These findings suggest that customized CM injection protocols may substantially reduce iodine dose while yielding higher image quality in SECT-100 kVp and DECT-65 keV abdominopelvic scans compared to SECT-120 kVp using fixed CM volumes.

Surgery and proton radiation therapy for pediatric base of skull chordomas: Long-term clinical outcomes for 204 patients.

BACKGROUND: Data on clinical outcomes for base of skull (BOS) chordomas in the pediatric population is limited. We report patient outcomes after surgery and proton radiotherapy (PRT). METHODS: Pediatric patients with BOS chordomas were treated with PRT or combined proton/photon approach (proton-based; for most, 80% proton/20% photon) at the Massachusetts General Hospital from 1981 to 2021. Endpoints of interest were overall survival (OS), disease-specific survival, progression-free survival (PFS), freedom from local recurrence (LC), and freedom from distant failure (DC). RESULTS: Of 204 patients, median age at diagnosis was 11.1 years (range, 1-21). Chordoma location included 59% upper and/or middle clivus, 36% lower clivus, 4% craniocervical junction, and 1% nasal cavity. Fifteen (7%) received pre-RT chemotherapy. Forty-seven (23%) received PRT, and 157 (77%) received comboRT. Median total dose was 76.7 Gy (RBE) (range, 59.3-83.3). At a median follow-up of 10 years (interquartile range, 5-16 years), 56 recurred. Median OS and PFS were 26 and 25 years, with 5-, 10-, and 20-year OS and PFS rates of 84% and 74%, 78% and 69%, and 64% and 64%, respectively. Multivariable actuarial analyses showed poorly differentiated subtype, radiographical progression prior to RT, larger treatment volume, and lower clivus location to be prognostic factors for worse OS, PFS, and LC. RT was well tolerated at a median follow-up of 9 years (interquartile range, 4-16 years). Side effects included 166 patients (80%) with mild/moderate acute toxicities, 24 (12%) patients with late toxicities, and 4 (2%) who developed secondary radiation-related malignancies. CONCLUSION: This is the largest cohort of BOS chordomas in the literature, pediatric and/or adult. High-dose PRT following surgical resection is effective with low rates of late toxicity.

Evaluation of Chemical and Microbiological Contaminants in Fresh Fruits and Vegetables from Peasant Markets in Cundinamarca, Colombia.

ABSTRACT: In this study, chemical and microbiological contaminants were detected in fresh fruits and vegetables in peasant markets in the Department of Cundinamarca to assess food safety. At least one pesticide was detected in 63% of the samples evaluated (n = 100, including fruits and vegetables), and in 41% of these, pesticides exceeded the maximum residue limit. Within the pesticides found, 60% do not use a registry from the Instituto Colombiano Agropecuario to be applied on the crops where they were detected and are included in the toxicological categories "highly toxic" (category IB) and "moderately toxic" (category II). Heavy metals were found in 45% of the samples, with cadmium (38%) and lead (14%) being the most frequent. The pathogenic microorganisms Escherichia coli O157:H7, Listeria monocytogenes, Salmonella, and Campylobacter sp. were detected in 4, 2, 1, and 0% of the samples, respectively. Factors concerning integrated crop management, contaminated inputs with chemicals and microorganisms, and the lack of hygiene in the postharvest stage favor the presence of pesticide residues, heavy metals, and the appearance of pathogenic microorganisms. The results suggest the need to strengthen the implementation of integrated management strategies that guarantee the safety of fresh fruits and vegetables in the country.

Systemically Administered Hemostatic Nanoparticles for Identification and Treatment of Internal Bleeding.

Internal bleeding is an injury that can be difficult to localize and effectively treat without invasive surgeries. Injectable polymeric nanoparticles have been developed that can reduce clotting times and blood loss, but they have yet to incorporate sufficient diagnostic capabilities to assist in identifying bleeding sources. Herein, polymeric nanoparticles were developed to simultaneously treat internal bleeding while incorporating tracers for visualization of the nanoparticles by standard clinical imaging modalities. Addition of 1,1'-dioctadecyl-3,3,3',3'-tetramethylindodicarbocyanine perchlorate (DiD; a fluorescent dye), biotin functionality, and gold nanoparticles to hemostatic polymeric nanoparticles resulted in nanoparticles amenable to imaging with near-infrared (NIR) imaging, immunohistochemistry, and X-ray computed tomography (CT), respectively. Following a lethal liver resection injury, visualization of accumulated nanoparticles by multiple imaging methods was achieved in rodents, with the highest accumulation observed at the liver injury site, resulting in improved survival rates. Tracer addition to therapeutic nanoparticles allows for an expansion of their applicability, during stabilization by first responders to diagnosis and identification of unknown internal bleeding sites by clinicians using standard clinical imaging modalities.

Mecanismos de acción y tratamiento del accidente cerebrovascular isquémico por COVID-19 / Mechanisms of action and treatment of ischemic stroke by COVID-19 / Mecanismos de ação e tratamento do AVC isquêmico pela COVID-19

Diversos mecanismos inflamatorios y protrombóticos pueden contribuir al aumento del riesgo de eventos cardiovasculares y accidentes cerebrovasculares en pacientes con COVID-19, afectando el enfoque del tratamiento y manejo de la enfermedad. La evidencia relacionada con los mecanismos fisiopatológicos del COVID-19 y su asociación con los accidentes cerebrovasculares son relevantes para guiar el tratamiento y el manejo de los pacientes, considerados como desafíos terapéuticos que surgen durante períodos de contagio masivo. Objetivo. Describir el mecanismo de acción y tratamiento del evento cerebro vascular isquémico por COVID-19. Metodología. Se realizó una revisión exhaustiva de la literatura mediante una revisión sistemática, en conformidad con las directrices establecidas por la declaración PRISMA. Se recopiló información de múltiples bases de datos científicas, utilizando términos y palabras clave ("Mecanismos de acción" OR "Mecanismos fisiopatológicos") AND ("Accidente cerebrovascular isquémico" OR "ACV isquémico") relacionados con los mecanismos de acción y tratamiento del accidente cerebrovascular isquémico asociado al COVID-19. Resultados. En total se obtuvo 41 entre PubMed y Science direct, previo a criterios 12 fueron seleccionados. Conclusión. Se determinaron los mecanismos de acción desencadenados por el COVID-19 para la formación de trombos y su relación con los accidentes cerebrovasculares. Además, se comprendió cómo el tratamiento de los accidentes cerebrovasculares afectaba a los pacientes que también padecían COVID-19. Se encontró que la tormenta de citocinas era un mecanismo influyente en la fisiopatología del COVID-19. En cuanto al tratamiento, la identificación de la enfermedad infecciosa causada por el virus SARS-CoV-2 resultó crucial en la gestión de los pacientes con accidente cerebrovascular.

Various inflammatory and prothrombotic mechanisms may contribute to the increased risk of cardiovascular events and stroke in patients with COVID-19, affecting the approach to treatment and management of the disease. Evidence regarding the pathophysiological mechanisms of COVID-19 and its association with stroke are relevant to guide the treatment and management of patients, considered as therapeutic challenges arising during periods of massive contagion. Objective. To describe the mechanism of action and treatment of ischemic cerebrovascular event by COVID-19. Methodology. A comprehensive review of the literature was performed by means of a systematic review, in accordance with the guidelines established by the PRISMA statement. Information was collected from multiple scientific databases, using terms and keywords ("Mechanisms of action" OR "Pathophysiological mechanisms") AND ("Ischemic stroke" OR "Ischemic stroke") related to the mechanisms of action and treatment of COVID-19-associated ischemic stroke. Results. A total of 41 were obtained between PubMed and Science direct, prior to criteria 12 were selected. Conclusion. The mechanisms of action triggered by COVID-19 for thrombus formation and its relation to stroke were determined. In addition, we gained insight into how stroke treatment affected patients who also had COVID-19. Cytokine storm was found to be an influential mechanism in the pathophysiology of COVID-19. In terms of treatment, identification of infectious disease caused by SARS-CoV-2 virus proved crucial in the management of stroke patients.

Vários mecanismos inflamatórios e pró-trombóticos podem contribuir para o aumento do risco de eventos cardiovasculares e acidente vascular cerebral (AVC) em pacientes com COVID-19, afetando a abordagem do tratamento e o manejo da doença. As evidências sobre os mecanismos fisiopatológicos da COVID-19 e sua associação com o AVC são relevantes para orientar o tratamento e o manejo dos pacientes, considerados como desafios terapêuticos que surgem durante períodos de contágio em massa. Objetivo. Descrever o mecanismo de ação e o tratamento do evento cerebrovascular isquêmico devido à COVID-19. Metodologia. Uma revisão abrangente da literatura foi realizada por meio de uma revisão sistemática, de acordo com as diretrizes estabelecidas pela declaração PRISMA. As informações foram coletadas de vários bancos de dados científicos, usando termos e palavras-chave ("Mechanisms of action" OR "Pathophysiological mechanisms") AND ("Ischaemic stroke" OR "Ischaemic stroke") relacionados aos mecanismos de ação e tratamento do acidente vascular cerebral isquêmico associado à COVID-19. Resultados. Foram obtidos 41 artigos no PubMed e no Science direct, e 12 foram selecionados de acordo com os critérios. Conclusão. Foram determinados os mecanismos de ação desencadeados pela COVID-19 para a formação de trombos e sua relação com o AVC. Além disso, entendemos como o tratamento do AVC afetou os pacientes que também tinham COVID-19. Descobriu-se que a tempestade de citocinas é um mecanismo influente na fisiopatologia da COVID-19. Em termos de tratamento, a identificação da doença infecciosa causada pelo vírus SARS-CoV-2 foi crucial no tratamento de pacientes com AVC.

Role of rapid kV-switching dual-energy CT in assessment of post-surgical local recurrence of pancreatic adenocarcinoma.

PURPOSE: The purpose of this study is to evaluate the performance of material-specific iodine (MS-I) images generated by rapid kV-switching single-source dual-energy computed tomography (rsDECT) for distinguishing post-operative changes from local tumor recurrence in patients on follow-up for pancreatic adenocarcinoma after surgical resection. METHODS: In this IRB-approved HIPPA-compliant study, retrospective review of 51 patients who underwent surgical resection of pancreatic adenocarcinoma was conducted and were followed up using contrast-enhanced rsDECT (Discovery CT 750HD, GE Healthcare, Milwaukee, WI). Independent qualitative assessment for presence of local tumor recurrence was performed by two radiologists who evaluated 65 keV (single-energy CT-equivalent interpretation) and 65 keV with MS-I (rsDECT interpretation) in separate sessions. Quantitative analysis of Hounsfield unit (HU, on 65 keV) and normalized iodine concentration (NIC on MS-I images; iodine concentration ratio in post-operative tissue to aorta) was measured. Follow-up imaging, temporal change of CEA and CA 19-9 or biopsy served as reference standard for presence and absence of local recurrence. Sensitivity and specificity of readers and quantitative parameters was calculated and receiver operating characteristic curves and Fisher's exact test were generated. A p value < 0.05 was considered statistically significant. RESULTS: A total of 51 patients (27 females, 24 males) with mean age of 64 years built the final cohort. Local recurrence was absent in 23 (Group A) and present in 28 (Group B) patients. The follow-up imaging was performed within 7 months of rsDECT. For both readers, the addition of MS-I increased the specificity for tissue characterization and improved reader confidence as compared to 65 keV (specificity: 80% and 56%, respectively) images alone. Quantitative analysis revealed a significantly lower NIC (0.28 vs. 0.35; p < 0.05) for non-recurrent tissue. However, HU was not significantly different for non-recurrent and recurrent tissue (0.63 vs. 0.70; p > 0.05). CONCLUSION: In inherently complex cases of post-operative pancreatic adenocarcinoma, MS-I images from rsDECT can be a useful adjunct to conventional scans in characterizing loco-regional soft tissue.

Iodine material density images in dual-energy CT: quantification of contrast uptake and washout in HCC.

PURPOSE: To determine the diagnostic potential of Material Density (MD) iodine images in dual-energy CT (DECT) for visualization and quantification of arterial phase hyperenhancement and washout in hepatocellular carcinomas compared to magnetic resonance imaging (MRI). MATERIALS AND METHODS: The study complied with HIPAA guidelines and was approved by the ethics committee of the institutional review board. Thirty-one patients (23 men, 8 women; age range, 36-87 years) with known or suspected Hepatocellular Carcinoma (HCC) were included. All of them underwent both single-source DECT and MRI within less than 3 months. Late arterial phase and portal venous phase CT imaging was performed with dual energies of 140 and 80 kVp, and virtual monoenergetic images (at 65 keV) and MD-iodine images were generated. We determined the contrast-to-noise ratio (CNR) for HCC in arterial phase and portal venous phase images. In addition, we introduced a new parameter which combines information of CNR in arterial and portal venous phase images into a single ratio (combined CNR). All parameters were assessed on monoenergetic 65 keV images, MD-iodine images, and MRI. Paired t test was used to compare CNR values in Mono-65 keV, MD-iodine, and MR images. RESULTS: CNR was significantly higher in the MD-iodine images in both the arterial (81.87 ± 40.42) and the portal venous phases (33.31 ± 27.86), compared to the Mono-65 keV (6.34 ± 4.23 and 1.89 ± 1.87) and MRI (30.48 ± 25.52 and 8.27 ± 8.36), respectively. Combined CNR assessment from arterial and portal venous phase showed higher contrast ratios for all imaging modalities (Mono-65 keV, 8.73 ± 4.03; MD-iodine, 119.87 ± 52.94; MRI, 34.87 ± 27.34). In addition, highest contrast ratio was achieved in MD-iodine images with combined CNR evaluation (119.87 ± 52.94, P < 0.001). CONCLUSION: MD-iodine images in DECT allow for a quantitative assessment of contrast enhancement and washout, with improved CNR in hepatocellular carcinoma in comparison to MRI.