Detectability of Small Low-Attenuation Lesions With Deep Learning CT Image Reconstruction: A 24-Reader Phantom Study.

BACKGROUND. Iterative reconstruction (IR) techniques are susceptible to contrast-dependent spatial resolution, limiting overall radiation dose reduction potential. Deep learning image reconstruction (DLIR) may mitigate this limitation. OBJECTIVE. The purpose of our study was to evaluate low-contrast detectability performance and radiation-saving potential of a DLIR algorithm in comparison with filtered back projection (FBP) and IR using a human multireader noninferiority study design and task-based observer modeling. METHODS. A dual-phantom construct, consisting of a low-contrast detectability module (21 low-contrast hypoattenuating objects in seven sizes [2.4-10.0 mm] and three contrast levels [-15, -10, -5 HU] embedded within liver-equivalent background) and a phantom, was imaged at five radiation exposures (CTDIvol range, 1.4-14.0 mGy; size-specific dose estimate, 2.5-25.0 mGy; 90%-, 70%-, 50%-, and 30%-reduced radiation levels and full radiation level) using an MDCT scanner. Images were reconstructed using FBP, hybrid IR (ASiR-V), and DLIR (TrueFidelity). Twenty-four readers of varying experience levels evaluated images using a two-alternative forced choice. A task-based observer model (detectability index [d']) was calculated. Reader performance was estimated by calculating the AUC using a noninferiority method. RESULTS. Compared with FBP and IR methods at routine radiation levels, DLIR medium and DLIR high settings showed noninferior performance through a 90% radiation reduction (except DLIR medium setting at 70% reduced level). The IR method was non-inferior to routine radiation FBP only for 30% and 50% radiation reductions. No significant difference in d' was observed between routine radiation FBP and DLIR high setting through a 70% radiation reduction. Reader experience was not correlated with diagnostic accuracy (R2 = 0.005). CONCLUSION. Compared with FBP or IR methods at routine radiation levels, certain DLIR algorithm weightings yielded noninferior low-contrast detectability with radiation reductions of up to 90% as measured by 24 human readers and up to 70% as assessed by a task-based observer model. CLINICAL IMPACT. DLIR has substantial potential to preserve contrast-dependent spatial resolution for the detection of hypoattenuating lesions at decreased radiation levels in a phantom model, addressing a major shortcoming of current IR techniques.

A Method for Reducing Variability Across Dual-Energy CT Manufacturers in Quantification of Low Iodine Content Levels.

BACKGROUND. Clinical use of the dual-energy CT (DECT) iodine quantification technique is hindered by between-platform (i.e., across different manufacturers) variability in iodine concentration (IC) values, particularly at low iodine levels. OBJECTIVE. The purpose of this study was to develop in an anthropomorphic phantom a method for reducing between-platform variability in quantification of low iodine content levels using DECT and to evaluate the method's performance in patients undergoing serial clinical DECT examinations on different platforms. METHODS. An anthropomorphic phantom in three body sizes, incorporating varied lesion types and scanning conditions, was imaged with three distinct DECT implementations from different manufacturers at varying radiation exposures. A cross-platform iodine quantification model for correcting between-platform variability at low iodine content was developed using the phantom data. The model was tested in a retrospective series of 30 patients (20 men, 10 women; median age, 62 years) who each underwent three serial contrast-enhanced DECT examinations of the abdomen and pelvis (90 scans total) for routine oncology surveillance using the same three DECT platforms as in the phantom. Estimated accuracy of phantom IC values was summarized using root-mean-square error (RMSE) relative to known IC. Between-platform variability in patients was summarized using root-mean-square deviation (RMSD). RMSE and RMSD were compared between platform-based IC (ICPB) and cross-platform IC (ICCP). ICPB was normalized to aorta and portal vein. RESULTS. In the phantom study, mean RMSE of ICPB across platforms and other experimental conditions was 0.65 ± 0.18 mg I/mL compared with 0.40 ± 0.08 mg I/mL for ICCP (38% decrease in mean RMSE; p < .05). Intrapatient between-platform variability across serial DECT examinations was higher for ICPB than ICCP (RMSD, 97% vs 88%; p < .001). Between-platform variability was not reduced by normalization of ICPB to aorta (RMSD, 97% vs 101%; p = .12) or portal vein (RMSD, 97% vs 97%; p = .81). CONCLUSION. The developed cross-platform method significantly decreased between-platform variability occurring at low iodine content with platform-based DECT iodine quantification. CLINICAL IMPACT. With further validation, the cross-platform method, which has been implemented as a web-based app, may expand clinical use of DECT iodine quantification, yielding meaningful IC values that reflect tissue biologic viability or treatment response in patients who undergo serial examinations on different platforms.

Virtual Unenhanced Dual-Energy CT Images Obtained with a Multimaterial Decomposition Algorithm: Diagnostic Value for Renal Mass and Urinary Stone Evaluation.

Background Virtual unenhanced (VUE) images obtained by using a dual-energy CT (DECT) multimaterial decomposition algorithm hold promise for diagnostic use in the abdomen in lieu of true unenhanced (TUE) images. Purpose To assess VUE images obtained from a DECT multimaterial decomposition algorithm in patients undergoing renal mass and urinary stone evaluation. Materials and Methods In this retrospective Health Insurance Portability and Accountability Act-compliant study, DECT was performed in patients undergoing evaluation for renal mass or urinary stone. VUE images were compared quantitatively to TUE images and qualitatively assessed by four independent radiologists. Differences in attenuation between VUE and TUE images were summarized by using 95% limits of agreement. Diagnostic performance in urinary stone detection was summarized by using area under the receiver operating characteristic curve, sensitivity, and specificity. Results A total of 221 patients (mean age ± standard deviation, 61 years ± 14; 129 men) with 273 renal masses were evaluated. Differences in renal mass attenuation between VUE and TUE images were within 3 HU for both enhancing masses (95% limits of agreement, -3.1 HU to 2.7 HU) and nonenhancing cysts (95% limits of agreement, -2.9 HU to 2.5 HU). Renal mass classification as enhancing mass versus nonenhancing cyst did not change (reclassification rate of enhancing masses, 0% [0 of 78]; 95% CI: 0, 5; reclassification rate of nonenhancing cysts, 0% [0 of 193]; 95% CI: 0, 2) with use of VUE in lieu of TUE images. Among 166 urinary stones evaluated, diagnostic performance of VUE images for stone detection was lower compared with that of TUE images (area under the receiver operating characteristic curve, 0.79 [95% CI: 0.73, 0.84] vs 0.93 [95% CI: 0.91, 0.95]; P < .001) due to reduced sensitivity of VUE for detection of stones 3 mm in diameter or less compared with those greater than 3 mm (sensitivity, 23% [25 of 108; 95% CI: 12, 40] vs 88% [126 of 144; 95% CI: 77, 94]; P < .001). Conclusion Compared with true unenhanced images, virtual unenhanced (VUE) images were unlikely to change renal mass classification as enhancing mass versus nonenhancing cyst. Diagnostic performance of VUE images remained suboptimal for urinary stone detection due to subtraction of stones 3 mm or less in diameter. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Sosna in this issue.

Through-the-Glass Portable Radiography of Patients in Isolation Units: Experience During the COVID-19 Pandemic.

OBJECTIVE. To reduce staff exposure to infection and maintain operational efficiency, we have developed a protocol to image patients using portable chest radiography through the glass of an isolation room. This technique is safe and easy to implement. Images are of comparable quality to standard portable radiographs. CONCLUSION. This protocol, used routinely by our department during the COVID-19 pandemic, can be applied to any situation in which the patient is placed in isolation.

Accuracy of Dual-Energy Computed Tomography Techniques for Fat Quantification in Comparison With Magnetic Resonance Proton Density Fat Fraction and Single-Energy Computed Tomography in an Anthropomorphic Phantom Environment.

OBJECTIVE: To investigate in an anthropomorphic phantom study the accuracy of dual-energy computed tomography (DECT) techniques for fat quantification in comparison with magnetic resonance (MR) proton density fat fraction (PDFF) and single-energy computed tomography (SECT), using known fat content as reference standard. METHODS: Between August 2018 and November 2020, organic material-based cylinders, composed of mixtures of lean and fat tissues mimics, iodine, and iron, were constructed to simulate varying fat content levels (0%, 10%, 15%, 25%, 50%, 75%, and 100%) in a parenchymal organ and were embedded into an anthropomorphic phantom simulating 3 patient sizes (circumference, 91, 126, and 161 cm). The phantom was imaged with multiecho MR, DECT, and SECT. Magnetic resonance PDFF, DECT fat fraction, and computed tomography (CT) numbers (SECT polychromatic and DECT monochromatic data, virtual unenhanced images) were estimated. Performances of MR PDFF and CT techniques to detect differences in fat content were measured using the area under the curve (AUC). Noninferiority of each CT technique relative to MR PDFF was tested using a noninferiority margin of -0.1. RESULTS: MR PDFF, DECT 140 keV monochromatic data, and fat fraction most closely correlated with known fat content (R2 = 0.98, 0.98, and 0.96, respectively). Unlike SECT and all other DECT techniques, DECT fat fraction was not affected by presence of iodine (mean difference, 0.3%; 95% confidence interval [CI], -0.9% to 1.5%). Dual-energy computed tomography fat fraction showed noninferiority to MR PDFF in detecting differences of 5% in fat content in medium-sized phantoms (ΔAUC, -0.05; 95% CI, -0.08 to -0.01), and 7% in large (ΔAUC, -0.04; 95% CI, -0.0 to 0.00) or extralarge sized phantoms (ΔAUC, -0.02; 95% CI, -0.07 to 0.00). CONCLUSIONS: Dual-energy computed tomography fat fraction shows linear correlation with true fat content in the range up to 50% fat fraction. Dual-energy computed tomography fat fraction has comparable estimation error and shows noninferiority to MR PDFF in detecting small differences in fat content across different body sizes.

CT Detectability of Small Low-Contrast Hypoattenuating Focal Lesions: Iterative Reconstructions versus Filtered Back Projection.

Purpose To investigate performance in detectability of small (≤1 cm) low-contrast hypoattenuating focal lesions by using filtered back projection (FBP) and iterative reconstruction (IR) algorithms from two major CT vendors across a range of 11 radiation exposures. Materials and Methods A low-contrast detectability phantom consisting of 21 low-contrast hypoattenuating focal objects (seven sizes between 2.4 and 10.0 mm, three contrast levels) embedded into a liver-equivalent background was scanned at 11 radiation exposures (volume CT dose index range, 0.5-18.0 mGy; size-specific dose estimate [SSDE] range, 0.8-30.6 mGy) with four high-end CT platforms. Data sets were reconstructed by using FBP and varied strengths of image-based, model-based, and hybrid IRs. Sixteen observers evaluated all data sets for lesion detectability by using a two-alternative-forced-choice (2AFC) paradigm. Diagnostic performances were evaluated by calculating area under the receiver operating characteristic curve (AUC) and by performing noninferiority analyses. Results At benchmark exposure, FBP yielded a mean AUC of 0.79 ± 0.09 (standard deviation) across all platforms which, on average, was approximately 2% lower than that observed with the different IR algorithms, which showed an average AUC of 0.81 ± 0.09 (P = .12). Radiation decreases of 30%, 50%, and 80% resulted in similar declines of observer detectability with FBP (mean AUC decrease, -0.02 ± 0.05, -0.03 ± 0.05, and -0.05 ± 0.05, respectively) and all IR methods investigated (mean AUC decrease, -0.00 ± 0.05, -0.04 ± 0.05, and -0.04 ± 0.05, respectively). For each radiation level and CT platform, variance in performance across observers was greater than that across reconstruction algorithms (P = .03). Conclusion Iterative reconstruction algorithms have limited radiation optimization potential in detectability of small low-contrast hypoattenuating focal lesions. This task may be further complicated by a high degree of variation in radiologists' performances, seemingly exceeding real performance differences among reconstruction algorithms. © RSNA, 2018 Online supplemental material is available for this article.

Accuracy and interobserver agreement of retroareolar frozen sections in nipple-sparing mastectomies.

In the last decades, surgical treatment of breast cancer has enormously changed. As a result, nipple-sparing mastectomy (NSM) has evolved as an oncologically safe and cosmetic approach. NSM includes a subareolar frozen section to evaluate malignancy. We determined the accuracy of subareolar frozen section diagnosis, analyzed the discrepancy factor, and estimated the interobserver agreement of frozen section in NSM. A retrospective review of all NSMs at our institution from 2009 to 2015 was performed. Frozen sections were compared to the final diagnoses to analyze the accuracy of subareolar frozen sections. Discordant results were rigorously evaluated to identify discrepancy factors. Some cases were randomly chosen to assess the interobserver agreement (kappa) among pathologists. The agreement results were evaluated with and without knowledge of the tumor morphology. Among 34 NSMs, the frozen section false-negative and false-positive rate was 5.9% and 8.8%, respectively. The sensitivity and specificity was 77.8% and 88.0%, respectively. Sampling errors and diathermy artifacts explained our false-negative diagnoses. Freezing artifacts and an intraductal papilloma explained our false-positive diagnoses. The interobserver agreement between breast and general pathologists was 0.87 (p<0.0001) and 0.31 (p=0.0001), respectively. The interobserver agreement increased to 0.35 (p<0.0001) in general pathologists with knowledge of the tumor morphology. Subareolar frozen section showed to be a specific test with moderate sensitivity. Papillary lesions can mimic atypical cells and influence the frozen section interpretation. Frozen section in NSM had a better performance in breast pathologists (almost perfect) versus general pathologists (fair). Interobserver agreement may improve with knowledge of tumor morphology.

Targeted CT Dose Reduction Using a Novel Dose Metric and the American College of Radiology Dose Index Registry: Application to Thoracic CT Angiography.

OBJECTIVE: The purpose of this article is to illustrate the use of the American College of Radiology Dose Index Registry data with a novel measurement of exposure to guide quality improvement efforts. MATERIALS AND METHODS: Using information from the Dose Index Registry report covering July through December 2012, we examined our relative ranking compared with the national median CT dose for the 20 most frequently performed examinations at our institution. The total exposure variance, defined as the difference between institutional and median national dose multiplied by the local examination frequency and expressed in units of mGy-persons, was calculated. Using this metric, two examinations were selected for investigation: pulmonary and thoracic CT angiography (CTA). Protocol modifications were implemented, and postintervention dose data were assessed from the report 1 year later. RESULTS: As indicated by size-specific dose estimates (SSDEs), the 2012 pulmonary CTA was within the national interquartile range; however, total exposure variance analysis showed that it presented the greatest opportunity for improvement on a population basis. Thoracic CTA was a top quartile examination and offered the second highest potential savings. After protocol modification, the average pulmonary CTA SSDEs decreased by 16%, for a population exposure savings of 1776 mGy-persons in the 2013 report. Average thoracic CTA SSDEs decreased by 44%, for a population exposure savings of 1050 mGy-persons. CONCLUSION: Total exposure variance analysis can increase the usefulness of Dose Index Registry data by relating per-examination dose differences to the local examination frequency. This study exhibited reduction of dose metrics for two commonly performed examinations.

Estimated skin dose look-up tables and their effect on dose awareness in the fluoroscopy-guided imaging suite.

OBJECTIVE: The displayed air kerma during a fluoroscopy-guided procedure often does not represent the entrance skin dose. The purpose of this work is to develop a system-specific air kerma-to-entrance skin dose look-up table (LUT) for immediate reference and to evaluate its clinical utility. MATERIALS AND METHODS: Physicists are often involved in retrospective dosimetry and risk estimates. Conservative dosimetry conversion factors, represented by the total conversion factor, prospectively estimate the maximum potential skin dose from the displayed air kerma. Air kerma-to-skin dose LUTs with corresponding tissue reactions and approximate time-of-onset can be posted for reference. By developing skin dose LUTs, physicians can actively evaluate during the procedure the potential for deterministic skin reactions. System user surveys evaluated the impact of LUTs on dose awareness. RESULTS: The range of the total conversion factor to the displayed air kerma for the nine systems evaluated was 0.8-1.6 for frontal x-ray tubes. Skin dose LUTs were posted in all imaging suites, and two surveys reported user feedback. Radiology technologists indicated that LUTs improved user dose awareness. Twelve of 14 physician respondents indicated an understanding that entrance skin dose is not equal to the displayed air kerma. CONCLUSION: Our efforts focused on educating fluoroscopy users about differences between displayed air kerma and the entrance skin dose while increasing dose awareness using an accessible and easy-to-understand tool. Skin dose LUTs provide physicians and staff an immediate reference for the maximum estimated entrance skin dose and the associated deterministic skin effects, allowing appropriate patient management.

Effective and organ specific radiation doses from videourodynamics in children.

PURPOSE: Effective and organ specific doses of ionizing radiation during videourodynamics are unknown. We estimated radiation exposure in children undergoing videourodynamics, and identified patient and examination factors that contribute to higher dosing. MATERIALS AND METHODS: Fluoroscopy data were collected from consecutive patients undergoing videourodynamics. Documented dose metrics were used to calculate entrance skin dose after applying a series of correction factors. Effective doses and organ specific doses (ovaries/testes) were estimated from entrance skin dose using Monte Carlo methods on a mathematical anthropomorphic phantom (ages 0, 1, 5, 10 and 15 years). Regression analysis was performed to determine patient and procedural factors associated with higher dosing. RESULTS: A total of 100 children (45% male, mean ± SD age 9.3 ± 5.7 years) were studied. Diagnoses included neurogenic bladder (73%), anatomical abnormality (14%) and functional/nonneurogenic disorder (13%). Mean fluoroscopy time was 0.17 ± 0.12 minutes. Mean age adjusted entrance skin dose, effective dose, and testis and ovary doses were 2.18 ± 2.00 mGy, 0.07 ± 0.05 mSv, 0.09 ± 0.10 mGy and 0.20 ± 0.13 mGy, respectively. On univariate analysis age, height, weight, body mass index, bladder capacity and fluoroscopy time were associated with effective dose. On multivariate adjusted analysis, body mass index, bladder capacity and fluoroscopy time were independently associated with effective dose. CONCLUSIONS: The average effective dose of ionizing radiation from videourodynamics was less compared to voiding cystourethrogram dose reported in the literature. Greater fluoroscopy time, body mass index and bladder capacity are independently associated with higher dosing.

Quantification and visualization of anterior pelvis bone density to optimize screw fixation: A novel technique.

Plate fixation of anterior pelvic ring fractures is often a vital component when surgically treating unstable pelvis fractures. Certain plate and screw configurations can have premature implant loosening, potentially in part due to insufficient pullout strength in lower density bone. This study sought to define densities about the anterior pelvic ring using a novel computer-based technique. Thirty-three patients who received a computed tomography (CT) of the abdomen/pelvis for reasons other than pelvis fracture in a 1-month time period were included. Three statistically distinct density regions of the anterior pelvis were identified based on the three-dimensional (3D) density map. The densest regions included both the anterior and posterior aspects of the superior pubic ramus, along with the region of bone along the inferior cotyloid fossa. The intermediate density region included the caudal and medial pubic body. The least dense region included the anterior aspect of the inferior pubic ramus (IPR), the posterior pubic body, and the posterior/inferior IPR. This study presents specific quantification of anterior pelvis bone density based on a novel technique using opportunistic CT scans. Clinical Significance: Anterior surgical fixation of unstable pelvic ring injuries may benefit from targeting areas of higher density as described in this novel technique.

Pediatric patients with lysosomal acid lipase deficiency.

Lysosomal acid lipase (LAL) deficiency is a rare, autosomal recessive disease caused by mutations in the LIPA gene, which produces cholesteryl ester and triglyceride accumulation predominantly in hepatocytes, adrenal glands, and gastrointestinal tract. We describe two new cases occurring in siblings, aged 5 and 7 years, who presented with hepatomegaly, dyslipidemia, and abnormal liver function. Percutaneous liver biopsy revealed portal inflammation, hypertrophic Kupffer cells with a foamy appearance and microvesicular steatosis with fibrosis. Immunostaining for lysosomal markers, cathepsin D and LAMP1 reflected the lysosomal nature of the lipid vacuoles. After enzymatic confirmation, enzyme replacement therapy was initiated for both siblings. Follow-up transaminase levels and lipid profiles showed a notable decrease in AST and ALT and a slight increase in HDL cholesterol. It is crucial to increase awareness of this rare condition among clinicians and pathologists. The expression of lysosomal markers around the lipid vacuoles might help diagnose LAL deficiency in pediatric patients.

Prevalence of SARS-CoV-2 infection and SARS-CoV-2-specific antibody detection among healthcare workers and hospital staff of a university hospital in Colombia.

Objective: The aim of this study was to determine current and previous SARS-COV-2 infection, and describe risk factors associated with seropositivity, among HCWs and hospital staff between June and October of 2020. Methodology: Data from the day of enrollment for a prospective cohort study were analyzed to determine point prevalence and seroprevalence of SARS-CoV-2 infection in HCWs and hospital staff of a university hospital in Colombia. Respiratory samples were collected to perform RT-PCR tests, along with blood samples to measure SARS-CoV-2 IgM and IgG antibodies. Data on nosocomial and community risk factors for infection were also collected and analyzed. Findings: 420 HCWs and hospital staff members were included. The seroprevalence at baseline was 23.2%, of which 10.7% had only IgM antibodies, 0.7% had IgG, and 11.7% had IgM and IgG. The prevalence of acute SARS-CoV-2 infection was 1.9%. Being a nurse assistant was significantly associated with seropositivity when compared with all other job duties (PR 2.39, 95% CI 1.27-3.65, p = 0.01). Conclusions: Overall SARS-CoV-2 prevalence was 1.9% and seroprevalence was 23.15%. Nurse assistants, medical doctors or students, and laboratory workers had a higher possibility of being SARS-CoV-2 seropositive.

Carcinoma of the rete testis: A rare testicular tumor.

Carcinoma of the rete testis is a rare malignant tumor which frequently occurs in middle-aged to older patients and has an aggressive biological behavior. We present the case of a 57-year-old man who presented with an ill-defined mass in the right testicle. The patient underwent a radical orchidectomy. Microscopic evaluation showed a neoplasm displaying a complex papillary-cystic architecture, infiltrating the testicular parenchyma. An in situ proliferation of neoplastic cells, with nuclear stratification and scanty cytoplasm was seen at the periphery, within the channels of the rete testis. The tumor infiltrated the tunica albuginea focally without disrupting it completely. Immunohistochemistry was positive for AE1/AE3, CK7, CK34ßE12, D2-40, and PAX8. Imaging studies presented no evidence of metastatic disease. These findings are those of a primary rete testis carcinoma. The transition between benign and neoplastic rete testis epithelium served as a helpful diagnostic clue. Metastatic carcinomas from other sites were considered in the differential diagnosis.

Thoracic target volume delineation using various maximum-intensity projection computed tomography image sets for radiotherapy treatment planning.

PURPOSE: Four-dimensional computed tomography (4D-CT) is commonly used to account for respiratory motion of target volumes in radiotherapy to the thorax. From the 4D-CT acquisition, a maximum-intensity projection (MIP) image set can be created and used to help define the tumor motion envelope or the internal gross tumor volume (iGTV). The purpose of this study was to quantify the differences in automatically contoured target volumes for usage in the delivery of stereotactic body radiation therapy using MIP data sets generated from one of the four methods: (1) 4D-CT phase-binned (PB) based on retrospective phase calculations, (2) 4D-CT phase-corrected phase-binned (PC-PB) based on motion extrema, (3) 4D-CT amplitude-binned (AB), and (4) cine CT built from all available images. METHODS: MIP image data sets using each of the four methods were generated for a cohort of 28 patients who had prior thoracic 4D-CT scans that exhibited lung tumor motion of at least 1 cm. Each MIP image set was automatically contoured on commercial radiation treatment planning system. Margins were added to the iGTV to observe differences in the final simulated planning target volumes (PTVs). RESULTS: For all patients, the iGTV measured on the MIP generated from the entire cine CT data set (iGTVcine) was the largest. Expressed as a percentage of iGTVcine, 4D-CT iGTV (all sorting methods) ranged from 83.8% to 99.1%, representing differences in the absolute volume ranging from 0.02 to 4.20 cm3; the largest average and range of 4D-CT iGTV measurements was from the PC-PB data set. Expressed as a percentage of PTVcine (expansions applied to iGTVeine), the 4D-CT PTV ranged from 87.6% to 99.6%, representing differences in the absolute volume ranging from 0.08 to 7.42 cm3. Regions of the measured respiratory waveform corresponding to a rapid change of phase or amplitude showed an increased susceptibility to the selection of identical images for adjacent bins. Duplicate image selection was most common in the AB implementation, followed by the PC-PB method. The authors also found that the image associated with the minimum amplitude measurement did not always correlate with the image that showed maximum tumor motion extent. CONCLUSIONS: The authors identified cases in which the MIP generated from a 4D-CT sorting process under-represented the iGTV by more than 10% or up to 4.2 cm3 when compared to the iGTVcine. They suggest utilization of a MIP generated from the full cine CT data set to ensure maximum inclusive tumor extent.

Merkel Cell Carcinoma and Diagnostic Experience in a Reference Hospital: A Case Series.

Merkel cell carcinoma (MCC) is a rare poorly differentiated neuroendocrine tumor, usually located in sun-exposed skin, with aggressive behavior and with high recurrence risk and metastatic disease. In Latin America, case series have been published, and it does not exceed 32 patients in 10 years, and in Colombia, there are case reports. We present a descriptive retrospective cross-sectional study in patients diagnosed with MCC in the Department of Pathology and Laboratories at the University Hospital Fundación Santa Fe de Bogotá(FSFB) between January 2003 and December 2018. We present the demographic, clinical, and pathological variables of these patients, as well as a literature review.

Esophageal tuberculosis in an HIV-positive patient mimicking a spindle cell tumor.

Tuberculosis (TB) of the esophagus is an extremely rare condition, even in immunocompromised patients. We report the case of a 24-year-old man with a past history of HIV and pulmonary tuberculosis who presented with dysphagia and a 2cm submucosal mass in the proximal esophagus. The biopsy was diagnosed as a spindle cell neoplasm in another center. Sections displayed a submucosal lesion formed by spindle and epithelioid cells, surrounded by chronic inflammation. The spindle cells were positive for S100 and CD68, but negative for cytokeratin, desmin, smooth muscle actin, ALK, CD34 and CD117. Ziehl-Neelsen stain was performed and showed many intracellular acid-fast bacilli, confirming the diagnosis of esophageal TB. This case is a reminder that esophageal TB may become manifest as a submucosal lesion and the histiocytic-granulomatous reaction may mimic a spindle cell tumor.

Epithelioid hemangioendothelioma of the parotid gland: A case report in an unusual location with a review of the literature.

Epithelioid hemangioendothelioma (EHE) is a malignant vascular tumor that usually affects the liver, lung, bone and deep soft tissues of the extremities or trunk. To our knowledge, only 3 cases in the parotid gland have been reported to date. We report a case of a 62-year-old woman who presented with a 1-year history of a slow-growing, painless mass over the left mandibular angle. Imaging studies showed a 2cm mass over the left parotid gland with peripheral calcifications. The patient underwent a superficial parotidectomy. Sections displayed neoplastic epithelioid cells with cytoplasmic vacuoles containing erythrocytes, surrounded by a myxohyaline stroma. Immunohistochemistry was positive for CD31, CD34, ERG, and factor VIII, but negative for cytokeratin AE1/AE3, CK7, EMA, SMA, and S100. The findings were those of an EHE involving the parotid gland. This case demonstrates an EHE in a rare location and emphasizes the need to consider this tumor when diagnosing uncommon soft tissue tumors of salivary glands.

Esophageal Pyogenic Granuloma: A Case Report and Review of the Literature.

Pyogenic granuloma (PG) is a capillary hemangioma mainly found in the skin and oral mucosa, but rarely described in the esophagus. We report the case of a 66-year-old man who consulted for retrosternal pain. Endoscopic studies showed a 28-mm polypoid mass located at the distal esophageal mucosa. The patient underwent endoscopic resection, and the histopathological examination showed a neoplastic proliferation of small blood vessels growing in a lobular architecture, with edematous stroma and prominent inflammatory infiltrate. Special stains for fungus showed pseudohyphae compatible with Candida spp. Findings were consistent with those of an esophageal PG associated with Candida infection. This case is a reminder that PG can be found in the esophagus, can be associated with other entities such as Candida infection, and is one of the differential diagnoses of neoplastic vascular proliferations that may mimic malignancy. In addition, we reviewed previously reported cases of esophageal PG.

Malignant Solitary Fibrous Tumor of the Humerus: A Case Report of an Extremely Rare Primary Bone Tumor.

Solitary fibrous tumor (SFT) is a spindle-shaped cell neoplasm originally described in the pleura, but subsequently found in many anatomic sites. Only few cases of primary SFTs in the bone have been previously described in the literature. We present the case of an 86-year-old man with a 1-week history of pain in his left arm. Imaging studies demonstrated a well-defined osteolytic lesion in the proximal humerus measuring 6.1 cm in diameter. Sections showed a round to spindle-shaped cell neoplasm with prominent mitotic activity (28 mitoses per 10 high-power fields) and areas of necrosis, focally surrounding staghorn-shaped vessels. The tumor cells were positive for CD34, CD99, Bcl-2, and STAT6 and negative for smooth muscle actin, epithelial membrane antigen, and cytokeratin AE1/AE3. These findings were consistent with a malignant SFT involving the left humerus. Although extremely rare, SFT should be considered in the differential diagnosis of primary bone tumors. This is the first case report of a primary SFT in a long bone with malignant histological features.