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.

Complementary role of magnetic resonance imaging in the study of the fetal urinary system.

Urinary system birth defects represent the abnormality most often detected in prenatal studies, accounting for 30% to 50% of all structural anomalies present at birth. The most common disorders are urinary tract dilation, developmental variants, cystic kidney diseases, kidney tumors, and bladder defects. These anomalies can present in isolation or in association with various syndromes. They are normally evaluated with sonography, and the use of magnetic resonance imaging (MRI) is considered only in inconclusive cases. In this article, we show the potential of fetal MRI as a technique to complement sonography in the study of fetal urinary system anomalies. We show the additional information that MRI can provide in each entity, especially in the evaluation of kidney function through diffusion-weighted sequences.

[Whole-body magnetic resonance imaging in a patient with an occult abdominal neuroblastoma and opsoclonus-myoclonus syndrome]. / Resonancia magnética de cuerpo entero en un caso de neuroblastoma abdominal oculto con síndrome opsoclonus-myoclonus.

Opsoclonus-myoclonus syndrome is a rare neurological disorder. In children, the etiology varies, although it is a paraneoplastic manifestation (mainly of neuroblastoma) in 40% to 80% of cases. Whole-body MRI promises to be a powerful tool in the search for a possible primary tumor in this condition for which the diagnostic algorithm is yet to be established. We present the case of a two-year-old boy with signs of opsoclonus-myoclonus syndrome in whom a retroperitoneal neuroblastoma was detected by whole-body MRI.

[Primary mesenteric extraskeletal osteosarcoma: imaging findings]. / Osteosarcoma extraesquelético mesentérico primario: hallazgos en imagen.

We present a case of extraskeletal osteosarcoma arising from the root of the mesentery. This location is extremely rare; to our knowledge only three other cases have been reported. We describe the findings at computed tomography, positron emission tomography, and bone scintigraphy. We emphasize the radiologic differential diagnosis in this case, which was complicated by the presence of other malignant abdominal disease.

Surgical clips vs. iodine-125 (125I) seeds for marking the location of nonpalpable malignant breast lesions: preliminary results. / Arpón quirúrgico vs. semilla de iodo (125I) en la localización de lesiones no palpables malignas de mama. Resultados preliminares.

OBJECTIVES: To assess the usefulness of iodine-125 (125I) seeds as an alternative to surgical clips for marking the location of nonpalpable malignant breast lesions for surgery. MATERIAL AND METHODS: We included patients with histologically confirmed nonpalpable malignant lesions treated by surgery in 2015 or 2016. Patients were randomly assigned to presurgical marking with metallic clips (Group A) or with 125I seeds (Group B). In both groups, marking was guided by ultrasound and/or mammography depending on the radiologic characteristics of the lesion. During surgery, a gamma probe was used and afterward the presence of seeds in the surgical specimen was checked radiologically. In the histological analysis, the absence of tumor in the stain was considered free margins. We analyzed the following variables: age, lesion characteristics (laterality, mean size on MRI and in the surgical specimen, radiological type), and presence/absence of free margins. RESULTS: In Group A (n=53), the most common histologic subtypes were infiltrating ductal carcinoma (IDC, 84.9%) and luminal A (LA, 49.1%); the mean size of the lesions was 1.8cm. In Group B (n=45), the most common histologic subtypes were IDC (82.2%) and LA (46.5%); the mean size of the lesions was 1.5cm. In Group A, 13.2% had involved margins and 13.2% underwent a second surgical intervention. In Group, B 11.4% had involved margins and 7.5% underwent a second surgical intervention. The differences between groups were not significant (p=0.7 for involved margins and p=0.5 for reintervention). The volume of the surgical specimens was significantly lower in Group B than in Group A (128.68cm3 vs. 189.37cm3; p<0.05). CONCLUSIONS: Using 125I seeds was feasible and enabled significantly smaller surgical specimens than using metallic clips.

Combined procedure of marking axillary positive node with iodine-125 seed and sentinel lymph node biopsy in breast cancer patients treated with neoadjuvant chemotherapy. / Procedimiento combinado de marcaje del ganglio axilar positivo biopsiado con semilla de yodo-125 y biopsia del ganglio centinela en pacientes con cáncer de mama tratadas con quimioterapia neoadyuvante.

OBJECTIVE: To present our initial experience in the combined procedure of intraoperative detection of axillary positive node marked with 125I seed (ML) and sentinel node biopsy (SLN) after neoadjuvant chemotherapy (NACT), in breast cancer patients. MATERIAL AND METHODS: Prospective study, January 2017 - March 2019, 16 breast cancer patients T1-3N1. TNM stage: IIA: 3, IIB: 10, IIIA: 3. Histological type ductal invasive: 14. Molecular subtype: luminal A: 3, luminal B: 9, HER2: 3, basal like: 1. The ML was marked 227±36 days before neoadjuvant chemotherapy (n: 10), or 1-6 days before surgery, on previously identified node by ultrasound visibility marker, hydrogel (n: 3) or three dimensional-3D (n: 3). Axillary lymphadenectomy was undertaken in 10 patients. RESULTS: ML and SLN were identified in the surgery in 93.7% (15/16) of the cases, in 33.3% (5/15) ML was not among SLN, and in only one patient (1/5) was there a discrepancy between the result of ML and SLN (macrometastases vs. negative 0/2). Median number of lymph nodes SLN: 2.2±0.9 (range 1-3) and AD: 13.5±5.2 (range 7-23). In all cases, histopathological analysis of ML, 125I seed and/or marker within, correctly predicted axillary status after neoadjuvant chemotherapy. In all patients the 125I radioactive seed was recovered. CONCLUSIONS: Placing of 125I seeds is a feasible technique for intraoperative location of axillary positive node combined with SLN. The histopathological result of ML allows the axillary status to be determined after neoadjuvant chemotherapy.

Hallazgos radiológicos en ecografía y tomografía computada multidetector de 64 canales de una invaginación colo-cólica secundaria a lipoma / Radiological findings on ultrasonography and multidetector computed tomography of 64 channels of a colo-colonic intussusception secondary to lipoma

Si bien la mayoría de los lipomas intestinales son asintomáticos y se diagnostican de manera casual, en algunas ocasiones pueden tener síntomas, como sangrado, diarrea o, con menor frecuencia, obstrucción o invaginación intestinal. Esta última en el adulto es una patología poco común y por lo general tiene una presentación subaguda crónica, cuyo diagnóstico es complicado. La principal técnica de imagen para el diagnóstico de la invaginación intestinal en adultos es la tomografía computada (TC). Solamente un 20% de las invaginaciones son colo-cólicas y en su mayoría son secundarias a un carcinoma. No obstante, en algunas pocas oportunidades pueden ser secundarias a una causa benigna, siendo el lipoma la más usual.

Even though most of the intestinal lipomas are asymptomatic and are diagnosed by chance, sometimes may have symptoms such as bleeding or diarrhea, and less frequently obstruction or intussusception. Intussusception in adults is a rare condition, and usually has a chronic-subacute presentation, and diagnosis is difficult. CT is the main radiological imaging test for diagnosis. Only 20% of the colonic invaginations are colo-colic, and in most cases are secondary to carcinoma. Rarely are secondary to a benign cause, being the intussusception secondary to a lipoma the most frecuent.