The 2021 SIIM-FISABIO-RSNA Machine Learning COVID-19 Challenge: Annotation and Standard Exam Classification of COVID-19 Chest Radiographs.

We describe the curation, annotation methodology, and characteristics of the dataset used in an artificial intelligence challenge for detection and localization of COVID-19 on chest radiographs. The chest radiographs were annotated by an international group of radiologists into four mutually exclusive categories, including "typical," "indeterminate," and "atypical appearance" for COVID-19, or "negative for pneumonia," adapted from previously published guidelines, and bounding boxes were placed on airspace opacities. This dataset and respective annotations are available to researchers for academic and noncommercial use.

Antibiotic therapy and staphylococcal skin infections in a tropical malarial zone (Guyana). Practices in conventional and exceptional situations.

A problem of community-acquired Staphylococcus aureus skin infections emerged in the French armed forces in 2004, in a malaria-endemic areas. The high incidence rate led us to evaluate military staff practices. This was a cross-sectional survey of doctors and nurses deployed as officers in French Guyana since 2006. The definition of skin and soft-tissue infection came from the criteria for epidemiological surveillance of the armed forces. We studied the management of antibiotic therapy and its related difficulties. In all, 47 officers responded. At the Military Medical Center (MMC), 23.4% of respondents routinely prescribed antibiotics, compared with 36.2% when stationed in the jungle (p<0.05%). Complication led 68.1 of staff to prescribe antibiotic prescriptions at the MMC, compared with 46.8% in the jungle (p<0.05%). Finally, 22.5% of those at MMC prescribed antibiotic coverage of surgical drainage, compared with 14.8% in the jungle (p<0.05%). Pristinamycin and fusidic acid were the preferred antibiotics. Two-thirds of the staff reported difficulties in jungle management. This first study indicates the need for an update of military medical recommendations. Personnel training must continue to enable them to provide appropriate aggressive management in the current endemic context.

[Medical particularities during prolonged demanding activity in a tropical forest. Experience of the tropical forest training center (French Guyana)]. / Spécificités médicales lors d'activités prolongées d'exception en zone équatoriale. Expérience du Centre d'entraînement en forêt équatoriale (Guyane).

A tropical forest is a hostile environment for humans. The military physician supporting these immersion activities must cope with varied clinical situations with limited resources to reduce operational unavailability. This article reports a prospective cross-sectional epidemiologic study conducted from January to May 2012, observing the daily activity at sick call during the rainy season at the tropical forest training center (CEFE) advanced jungle commando training, located in French Guyana. The aim was to observe the distribution of traumatic injuries and specific diseases in this tropical environment. In all, 9,221 army staff members participated in the training (mean age: 30.8 years) during the 120-day study period. There were 486 medical visits, for a mean daily incidence of 5.3% (trainees: 83.8%, trainers: 16.5%). Skin lesions were most frequent (39%), principally irritative dermatitis and skin maceration (moisture/dressing associated dermatitis). A third (34%) of these conditions were due to trauma, mainly limb contusions and ligament injuries. Tropical diseases accounted for 3% of the reasons for consultation, with rare problems related to equatorial fauna or flora. The remaining conditions (24%) were not specific to the environment or activity. Operational attrition averaged five days. Removal from the training course was necessary in 13.8% of the cases. In an isolated area with a demanding environment , edical practice in a tropical forest requires health prevention actions and close medical follow-up. The permanent presence of a physician provides both care and expertise and is an important asset for both trainees and trainers.

Invasive polymycotic pneumonia in an uncontrolled diabetic.

We describe the clinical course of a patient with invasive polymycotic pneumonia due to Rhizopus arrhizus and Candida albicans. Both organisms were recovered from antemortem sputum cultures, and their clinical significance was confirmed by histologic examination of the lungs at autopsy. Circumstances leading to polymycotic infection are discussed, with special attention given to polymycotic infections involving Zygomycetes.

[Pulmonary torsion of the right superior lobe: an unusual complication secondary to surgery]. / Torsión pulmonar del lóbulo superior derecho: una complicación inusual secundaria a cirugía.

Pulmonary torsion is a serious complication consisting of the rotation of the pulmonary parenchyma upon its vascular pedicle. Torsion is usually related to lung surgery and may lead to death. Early diagnosis allows for the rapid treatment that is essential for preventing death and decreasing associated complications.

[Rounded nodular atelectasis: computerized tomography and magnetic resonance appearances]. / Atelectasias redondas nodulares: apariencia en tomografía computarizada y resonancia magnética.

Rounded atelectasis is a rare form of lung collapse whose X-ray appearance can be confused with that of tumors, especially nodular forms. We studied 14 such lesions with computerized tomography, finding that all were rounded and subpleural, specifically in the thickened pleura visceralis. The radiological sign that was most useful for diagnosis was the arc of the proximal vessels in the direction of the lesion. Such an arc was present in all the cases we reviewed. Other radiological signs such as brightness of the surrounding parenchyma, loss of volume in the affected lobe and the presence of air bronchogram were found in 10, 7 and 7 patients, respectively. When the X-ray appearance clearly indicates a diagnosis of rounded nodular atelectasis, we recommend that no additional diagnostic procedure be made. Three lesions in our sample were studied by magnetic resonance, which revealed the characteristic hypointense curves in all sequences done on 2 patients. The usefulness of computerized tomography in the diagnosis of this entity relegates magnetic resonance to a second plane.

Digital fractures. A comprehensive review.

Fractures of the phalanges of the feet are the most common types of injury to the forefoot. There is, however, little available literature concerning pedal digital fractures. There is a misconception that fractured toes will heal by themselves. In fact, mistreated digital fractures can lead to many painful and serious complications. A review of the classifications, mechanisms of injury, clinical presentation, complications, and various treatments of digital fractures is presented.

[Percutaneous nephrostomy. Review of 92 cases]. / Nefrostomías percutáneas. Revisión de 92 casos.

Presentation of 92 nephrostomies percutaneous in 70 patients. Nephrostomy was bilateral in 5 cases. Three patients had collections of renal origin (2 urinomas and 1 abscess) which were treated percutaneously. The indication for nephrostomy was in all cases obstruction of the collector system, with one exception where the indication was ureteral fistula. Origin was lithiasis in 53 cases, 15 cases vesical carcinoma, 3 post-surgical iatrogenic stenosis, 1 fistula and formation of urinoma after lithotrity, 5 prostate carcinoma infiltration, 8 infectious origin, 4 congenital and 1 due to glandular cystitis. 9 patients were monorenal. In 6 patients leucocytosis was present, 4 has fever, and in 11 coexisted fever and leucocytosis. High creatinine and urea levels were present in 55.7% and 41% patients, respectively.. Renal puncture through lower calyceal group was the preferred option. Purulent urine was obtained in 17 cases. With regard to nephrostomy complications haematuria occurred in 30 cases (only in 9 it lasted more than 1 day); and there was 1 case of pararenal haematoma. Pain was significant in 12% procedures and contrast extravasation resulted in 14% cases (in all of them proper positioning of nephrostomy catheter was possible). Spontaneous expulsion and the subsequent replacement of the catheter occurred in 12 cases. On average, residence time of catheter was 44.8 days. In all cases both the patient's signs and symptoms, and the laboratory results were improved.

[Diagnostic effectiveness of CT and MR in local staging of renal tumors]. / Eficacia diagnóstica del TC y RM en el estadiaje local de los tumores renales.

The aim of this paper is to study the pre-operative staging of renal tumours, comparing CT and MR, and the imaging criteria used, examining the diagnostic efficacy for each of them. Thirty-four tumours were obtained from 29 patients. All cases were studied with CT and MR. To measure diagnostic efficacy, both for each technique and the criteria used in 2 different readings, a diagnostic performance curve (DPC) is calculated. Neither CT nor MR show infiltration of renal capsule. With regard to perinephritic fat, fascia and adjacent organ invasion, both techniques lead to overstaging, mainly CT. When applying more conservative reading criteria, the results are much improved, specially in relation to CT, although results with MR continue to be more favourable. MR is better to study vascular invasion, providing no false results. Of 22 tumours undergoing surgery, first option was the correct staging in 14 tumour with CT and in 16 with MR. When selecting the best imaging technique to stage renal tumours, MR allows a better and simpler radiologic reading. Nevertheless, considering the high correlation between CT and MR, CT can be used more reliably in institutions where no easy access to a MR unit is available. Both CT and MR overstage renal tumours.

[Morphological characterization of trabecular bone structure using high resolution magnetic resonance imaging]. / Caracterización morfológica de la estructura trabecular ósea mediante resonancia magnética de alta resolución.

OBJECTIVE: The morphological analysis of trabecular bone of the distal epiphysis of the radius and its three-dimensional representation allow an adequate evaluation of bone quality. We analyzed trabecular bone morphology and its three-dimensional modeling with high resolution magnetic resonance imaging (MRI) to determine the parameters that provide useful information about bone condition. MATERIAL AND METHODS: All data were acquired using 3D T1-weighted gradient-echo sequences in a 3-Tesla MRI scanner. The mathematical algorithms required to study trabecular bone structure were developed in a Matlab environment on a personal computer. A total of 16 healthy subjects (10 women and 6 men; aged 23 to 54 years, mean 36+/-10 years) were studied. No significant differences were found between women (mean age 39+/-12, range: 23-54 years) and men (mean age 33+/-6, range: 25-42) (p = 0.285). Healthy subjects were recruited from among normal subjects studied to assess the ligaments of the wrist. The morphological parameters analyzed were trabecular volume, mean trabecular thickness, mean trabecular separation, and trabecular index. RESULTS: The morphological parameters that were useful in the evaluation of bone quality were trabecular volume (women: 23.22+/-1.78%; men: 27.49+/-1.30%), trabecular thickness (women: 0.1901+/-0.0014 mm; men: 0.1935+/-0.0014 mm), trabecular separation (women: 0.8332+/-0.0440 mm; men: 0.7697+/-0.0258 mm), and the number of trabeculae (women: 1.2215+/-0.0920 mm-1; men: 1.4207+/-0.0640 mm-1). Statistically significant differences between men and women were found for all the parameters analyzed; no significant differences were found in relation with age in this series. CONCLUSIONS: High resolution MRI enabled the morphological characterization of the trabecular bone structure; this represents an advance in the detection of biomarkers for disease.

Hepatic mesenchymal sarcoma: MRI findings.

Hepatic undifferentiated mesenchymal sarcoma is a rare pediatric malignant neoplasm. We present three children, aged 7, 8, and 12 years, with this tumor. Clinical presentation was abdominal pain, palpable mass, asthenia, anorexia, and weight loss. One had jaundice. All three lesions were detected on ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI). MRI localized the lesions more accurately than the other methods, with good resectability correlation. On MRI, these tumors were markedly hyperintense on long TR/TE spin-echo (SE) and short-time inversion recovery (STIR) sequences. This was due to the cystic areas with myxoid material and necrosis. The internal separations were hypointense on these sequences. On short TR/TE SE sequences the lesions presented a fibrous pseudocapsule (two cases), and internal hyperintense areas representing hemorrhage (two cases). MRI also detected vascular invasion (one case), biliary obstruction (one case), and hilar adenopathies (one case). The combination of hemorrhage (hyperintense on short TR/TE SE) and cystic or myxoid components (markedly hyperintense on long TR/TE SE and STIR sequences) is common in this tumor.

Pseudotumoral presentation of nodular regenerative hyperplasia of the liver: imaging in five patients including MR imaging.

Nodular regenerative hyperplasia (NRH) of the liver is a condition characterized by multiple monoacinar regenerative nodules in the absence of fibrous septa. When these nodules become confluent they may be seen with sonography or CT. The appearance of these pseudotumoral pattern of NRH has been scarcely described with MRI. We present the imaging findings of five patients with NRH and a pseudotumoral form at sonography. Sonography depicted hyperechoic lesions in four patients and hypoechoic lesions in another. Computed tomography showed hypodense lesions with little contrast enhancement in two patients. Three patients showed subtle focal liver lesions on MRI: isointense in one, mildly hypointense in another, and minimally hyperintense in a patient with siderosis. The dynamic behavior at MRI was similar to the normal liver parenchyma. Hyperechoic lesions on sonography or hypodense lesions on CT, barely or not seen on MRI, can be indicative of NRH in an appropriate clinical setting.

The value of fat-suppressed T2 or STIR sequences in distinguishing lipoma from well-differentiated liposarcoma.

The objective of this study was to evaluate the diagnostic value of fat-suppressed T2-weighted (FS-T2) images or short tau inversion recovery (STIR) imaging in distinguishing lipoma from lipoma-like subtype of well-differentiated liposarcoma. Spin-echo T1-weighted and STIR or fat-suppression T2-weighted sequences were performed in 60 lipomas and 32 lipoma-like well-differentiated liposarcomas, histologically proven, looking for thick septa or nodules in T1-weighted images and linear, nodular, or amorphous hyperintensities on FS-T2/STIR sequences. Fourteen lipomas (23.3%) showed thick septa and/or nodules on T1, whereas on FS-T2 or STIR sequences only seven (11.7%) displayed hyperintense nodules and/or septa. All well-differentiated liposarcomas contained these signs on FS-T2 or STIR sequences. The presence of hyperintense septa or nodules in a predominantly lipomatous tumor on FS-T2/STIR sequences helps to differentiate malignant tumors from lipomas. Employing the presence of hyperintense nodules and/or septa as criteria of malignancy specificity was 76.6% and sensitivity 100%. Overdiagnoses of well-differentiated liposarcoma can occur due to the presence of non-lipomatous areas within lipomas.

Massive intrahepatic extramedullary hematopoiesis in myelofibrosis.

We describe the sonographic (US) and computed tomographic appearances of a large, solitary tumor in the liver produced by extramedullary hematopoiesis in an 82-year-old patient with agnogenic myeloid metaplasia. Confirmation of this diagnosis was made by US-guided fine-needle aspiration biopsy.

Grading of subcutaneous soft tissue tumors by means of their relationship with the superficial fascia on MR imaging.

OBJECTIVE: To assess the diagnostic value of the relationship between subcutaneous tumors and the superficial fascia in the characterization of soft-tissue masses. DESIGN: MR studies of 64 soft tissue masses located in the subcutaneous space were reviewed. We established five grades of relationship between tumors and superficial fascia and analyzed the probability of the lesions in each group being malignant. Group 1 tumors did not contact the fascia; group 2 lesions contacted it slightly, with acute angles between the tumor and the fascia; group 3 lesions had wider contact with larger acute or right angles; group 4 tumors had even wider contact with obtuse angles with the fascia; and group 5 was composed of lesions that crossed the superficial fascia. RESULTS: The probability of a subcutaneous lesion that crosses the superficial fascia being malignant was 6.88 times greater than for lesions that did not cross the fascia. For lesions forming obtuse angles with the fascia the probability of malignancy was 6.3 times greater than that of tumors that did not present this sign. All histologically verified fascial infiltrations occurred in malignant lesions of groups 4 and 5. CONCLUSIONS: Malignant tumors of the subcutaneous compartment have a higher tendency to develop a close relationship with the fascia than benign lesions. Obtuse angles between superficial fascia and a subcutaneous mass or a lesion crossing the fascia strongly suggest malignancy.