Snapping syndromes occur during certain movements in several joints and may be accompanied by local pain and crepitation or audible snapping sensation. Snapping joints may eventually have no pathologic significance and in this case no treatment is required. There is an array of intra- and extra-articular causes of snapping syndrome and the lack of precise clinical findings impairs the definition of the most appropriate imaging method to confirm the diagnosis. The present study is aimed at discussing the most frequent causes of snapping syndrome in different joints, emphasizing the indications and limitations of each of the different diagnostic methods in specific situations of the clinical practice.

Keywords: Joints, Snapping, Ultrasonography, Computed tomography, Magnetic resonance imaging

OBJECTIVE: The present study was aimed at describing uncommon presentations of intraosseous hemophilic pseudotumor in imaging diagnosis. MATERIALS AND METHODS: Retrospective study evaluating five hemophilic pseudotumors in bones of two patients with hemophilia A. Imaging findings were consensually evaluated by two musculoskeletal radiologists. Plain radiography, computed tomography and magnetic resonance imaging studies were analyzed. RESULTS: At contrast-enhanced computed tomography images, one of the lesions on the left thigh was visualized with heterogeneously enhanced solid areas. This finding was later confirmed by anatomopathological study. Another uncommon finding was the identification of a healthy bone portion interposed between two intraosseous pseudotumors in the humerus. And, finally, a femoral pseudotumor with extension towards soft tissues and transarticular extension, and consequential tibial and patellar involvement. CONCLUSION: The above described imaging findings are not frequently reported in cases of intraosseous pseudotumors in hemophilic patients. It is important that radiologists be aware of these more uncommon presentations of intraosseous pseudotumors.

Keywords: Magnetic resonance imaging, Pseudotumor, Hemophilia

Gadolinium-based contrast agents are much safer than the iodinated ones; however complications may occur and should be recognized for appropriate orientation and management. The total incidence of adverse reactions to contrast agents in magnetic resonance imaging ranges between 2% and 4%. Cases of severe acute reactions to gadolinium, such as laryngospasm and anaphylactic shock, are rare. Chronic complications secondary to the use of gadolinium also can occur and, recently an association between its use and a rare dermatologic disease occurring in patients with renal failure has been reported. Nephrogenic systemic fibrosis was the subject of an official health notification issued by the American Food and Drug Administration. This progressive disease is characterized by hardened skin with fibrotic nodules and plaques which may involve other parts of the body. Patients who have been affected by this disorder presented chronic renal failure, with metabolic acidosis and had been submitted to magnetic resonance angiography, probably involving exposure to large amounts of intravenous paramagnetic contrast. This review is aimed at presenting a succinct description of the gadolinium-based contrast agent types, possible secondary complications, their preventive measures and management.

Keywords: Magnetic resonance imaging, Gadolinium, Adverse reaction

OBJECTIVE: To determine the incidence of most significant radiological findings of paracoccidioidomycosis and to verify its possible variants. MATERIALS AND METHODS: One hundred and seventy-three cases of paracoccidioidomycosis presented between 1970 and 1980 were reviewed, including their radiological workup reanalysis by at least two experienced radiologists. RESULTS: Ninety-four cases were pulmonary only and 38 were pulmonary associated with ganglial, visceral and osseous lesions or in association with tuberculosis. There was no pulmonary involvement in 41 cases, presenting small bowel, viscera, bone lesions, or a combination of these. Most significant radiological findings in cases of pulmonary involvement were bilateral, diffuse reticular and nodular interstitial infiltrate, followed by the diffuse bilateral alveolar form. Visceral and gastrointestinal tract lesions presented predominantly with liver, jejunum and ileum involvement. Lymph nodal involvement was predominantly diffuse, abdominal or peripheral. In bones, osteolytic lesions affected predominantly long bones and clavicle. CONCLUSION: Paracoccidioidomycosis is a granulomatous disease commonly found in Brazil, primarily affecting lungs, caused by inhalation of fungus spores. Other rare or less frequent forms of the disease should be taken into consideration for differential diagnosis.

Keywords: Paracoccidioidomycosis, Granulomatous disease

OBJECTIVE: To evaluate the contribution of abdominal ultrasound in the follow-up of a group of post-treatment breast cancer patients. MATERIAL AND METHODS: We retrospectively studied the findings of abdominal ultrasound examinations of 100 patients treated for primary breast cancer. These patients were attended from January to December of 1997 at the Ultrasound Sector, Division of Radiology of the Department of Clinical Medicine of the "Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo", SP, Brazil. Information such as age, histological type, staging, number of examinations and ultrasound findings were rated and analyzed. RESULTS: Abdominal ultrasound was normal in 70% of the patients whereas liver metastases were diagnosed in 3% of the patients. CONCLUSION: The majority of the abnormalities identified were not directly related to complications of breast cancer.

Keywords: Breast cancer, Abdominal ultrasound, Follow-up

OBJECTIVE: To study the feasibility of reducing radiation dose in protocols for acquisition of helical computed tomography images in a University Hospital. MATERIALS AND METHODS: A survey of radiation doses in computed tomography protocols was performed with phantoms and ionization chamber. Changes in kVp and mAs were proposed, determining the average noise. Protocols with noise values < 1% were submitted to qualitative assessment of contrast and spatial resolution by three observers. RESULTS: Tests of variations were performed with 22 protocols for pediatric skulls, 26 for adult skulls, 28 for abdomen, and 18 for chest. The reduction in dose achieved ranged between 7.4% and13% for pediatric skull, 3.8% and 25% for adult skull, 9.6% and 34.3% for abdomen, 6.4% and 12% for chest. It was also noted that the use of windowing and zoom tools supported the acceptance of images by the observers. CONCLUSION: Radiation dose levels can be reduced by up to 34.4% in comparison with routine protocols, keeping the noise at acceptable levels. The use of digital manipulation tools allowed the acceptance of images with higher noise levels, thus resulting in radiation dose reduction.

Keywords: Computed tomography; Radiation dose reduction; ALARA; Signal-to-noise ratio; CTDI; Optimization.

The objective of the present essay was to encourage a careful evaluation of periosteal reactions on magnetic resonance images. The initial approach to bone lesions is made by conventional radiography and, based on the imaging findings, periosteal reactions are classified into classical subtypes. Although magnetic resonance imaging is considered as the gold standard for local staging of bone tumors, the utilization of such method in the study of periosteal reactions related to focal bone lesions has been poorly emphasized, with relatively few studies approaching this subject. The literature review revealed a study describing an experimental animal model of osteomyelitis suggesting that magnetic resonance imaging is superior to other imaging methods in the early identification of periosteal reactions. Another study has suggested a good correlation between conventional radiography and magnetic resonance imaging in the identification and classification of periosteal reactions in cases of osteosarcoma. The present essay illustrates cases of periosteal reactions observed at magnetic resonance imaging in correlation with findings of conventional radiography or other imaging methods.

Keywords: Periostitis; Bone neoplasm; Magnetic resonance imaging.

Short bowel syndrome is defined as the small bowel functional absorptive surface inability to provide adequate nutrition, leading to intestinal failure and chronic malnutrition. In adult individuals the main etiologies for short bowel syndrome are related to extensive or multiple surgical bowel resections secondary to mesenteric ischemia, Crohn’s disease and actinic enteritis. Besides evaluating the transit time through the large bowel, barium follow through may be utilized in the measurement of bowel remnants length as well as in the follow-up of structural adaptation phenomena of small bowel and colonic loops. In patients with short bowel syndrome, structural small bowel adaptation consists in hyperplasia of villi and mucosal folds, which become more numerous, deeper and larger in diameter, as well as remnant segment dilation. Such morphological findings are more prominent and best established in the ileal loops, whose remarkable adaptive capacity has been well documented. Therefore, the knowledge of imaging findings regarding morphological and adaptive characteristics of the small bowel is extremely relevant in the multidisciplinary approach to short bowel syndrome.

Keywords: Short bowel syndrome; Radiology; Adaptation.

Objetivo: Avaliar a percepção de médicos residentes em radiologia de 4º ano sobre as melhores modalidades de imagem na investigação de neoplasias e trauma. Materiais e Métodos: Vinte e sete médicos residentes de 4º ano de quatro programas de residência em radiologia americanos participaram do estudo. Aos participantes foi perguntado sobre a melhor modalidade de imagem para se avaliar o cérebro e a coluna vertebral, pulmões, abdome e o sistema musculoesquelético. As modalidades de imagem disponíveis foram: RM, TC, ultrassonografia, PET e radiografia simples. Todos os achados foram comparados com os Critérios de Adequação de Exames de Imagem e Radioterapia do ACR. Resultados: A RM foi escolhida como melhor modalidade de imagem para se avaliar neoplasias encefálicas, espinhais, abdominais e musculoesqueléticas por 96,3%, 100%, 70,4% e 63% dos residentes, respectivamente. A TC foi escolhida por 88,9% dos residentes para avaliar neoplasias pulmonares. A modalidade de imagem ótima para se avaliar trauma foi a TC para lesões encefálicas (100%), espinhais (92,6%), pulmonares (96,3%), abdominais (92,6%) e grandes lesões traumáticas musculoesqueléticas (74,1%); a RM foi escolhida para lesões esportivas (96,3%). Observou-se concordância com os critérios de adequação do ACR. Conclusão: Houve concordância entre a percepção dos residentes sobre as melhores modalidades de imagem para avaliação de neoplasias e trauma e os critérios de adequação do ACR.

Keywords: Formação de residentes; Educação médica; Modalidades de imagem.

Gossypiboma is a term utilized to describe a mass developed from a matrix of cotton fibers surrounded by inflammatory granulomatous reaction. Its incidence is estimated at 0.15% to 0.2% of laparotomies. A foreign body within the abdominal cavity may provide a niche for proliferation of microorganisms, acting as primary focus for development of an abscess and peritonitis. Several studies have demonstrated the relevance of clinical correlation with the findings of different imaging methods (conventional radiography, ultrasonography, computed tomography and magnetic resonance imaging) in the diagnosis of gossypibomas. The present pictorial essay is aimed at demonstrating a series of typical cases of abdominal gossypibomas and illustrating the several presentations of such mass, with emphasis on the findings at different imaging methods in order to familiarize radiologists with this entity and with the main differential diagnosis.

Keywords: Gossypiboma; Abdominal; Imaging diagnosis.

OBJECTIVE: To describe key imaging findings in a series of cases of primary neuroendocrine tumors of the lung (NTLs), with emphasis on computed tomography changes. MATERIALS AND METHODS: Imaging studies of 22 patients (12 men, mean age 60 years) with histopathologically confirmed diagnosis, evaluated in the authors's institution during the last five years were retrospectively reviewed by two radiologists, with findings being consensually described focusing on changes observed at computed tomography. RESULTS: The authors have described five typical carcinoids, three atypical carcinoids, three large-cell neuroendocrine carcinomas (LCNCs), and 11 small-cell lung cancers (SCLCs). Only one typical carcinoid presented the characteristic appearance of central endobronchial nodule with distal pulmonary atelectasis, while the others were pulmonary nodules or masses. The atypical carcinoids corresponded to peripheral heterogeneous masses. One out of the three LCNCs was a peripheral homogeneous mass, while the others were ill-defined and heterogeneous. The 11 SCLCs corresponded to central, infiltrating and heterogeneous masses with secondary pleuropulmonary changes. Calcifications were absent both in LGNCs and SCLCs. Metastases were found initially and also at follow-up of all the cases of LCNCs and SCLCs. CONCLUSION: Although some imaging features may be similar, radiologic findings considered together with clinical information may play a relevant role in the differentiation of histological types of NTLs.

Keywords: Computed tomography; Lung neoplasms; Neuroendocrine tumors.

OBJECTIVE: To evaluate a comprehensive MRI protocol that investigates for cancer, vascular disease, and degenerative/inflammatory disease from the head to the pelvis in less than 40 minutes on a new generation 48-channel 3T system. MATERIALS AND METHODS: All MR studies were performed on a 48-channel 3T MR scanner. A 20-channel head/neck coil, two 18-channel body arrays, and a 32-channel spine array were employed. A total of 4 healthy individuals were studied. The designed protocol included a combination of single-shot T2-weighted sequences, T1-weighted 3D gradientecho pre- and post-gadolinium. All images were retrospectively evaluated by two radiologists independently for overall image quality. RESULTS: The image quality for cancer was rated as excellent in the liver, pancreas, kidneys, lungs, pelvic organs, and brain, and rated as fair in the colon and breast. For vascular diseases ratings were excellent in the aorta, major branch vessel origins, inferior vena cava, portal and hepatic veins, rated as good in pulmonary arteries, and as poor in the coronary arteries. For degenerative/inflammatory diseases ratings were excellent in the brain, liver and pancreas. The inter-observer agreement was excellent. CONCLUSION: A comprehensive and time efficient screening for important categories of disease processes may be achieved with high quality imaging in a new generation 48-channel 3T system.

Keywords: Whole-body MRI; Screening; Protocol; Preliminary results; 3 tesla.

Rendu-Osler-Weber syndrome or hereditary hemorrhagic telangiectasia is an autosomal dominant vascular disease involving multiple systems whose main pathological change is the presence of abnormal arteriovenous communications. Most common symptoms include skin and mucosal telangiectasias, epistaxis, gastrointestinal, pulmonary and intracerebral bleeding. The key imaging finding is the presence of visceral arteriovenous malformations. The diagnosis is based on clinical criteria and can be confirmed by molecular biology techniques. Treatment includes measures for management of epistaxis, as well as surgical excision, radiotherapy and embolization of arteriovenous malformations, with emphasis on endovascular treatment. The present pictorial essay includes a report of three typical cases of this entity and a literature review.

Keywords: Rendu-Osler-Weber; Hereditary hemorrhagic telangiectasia; Arteriovenous fistula; Epistaxis.

Whole-body imaging in children was classically performed with radiography, positron-emission tomography, either combined or not with computed tomography, the latter with the disadvantage of exposure to ionizing radiation. Whole-body magnetic resonance imaging (MRI), in association with the recently developed metabolic and functional techniques such as diffusion-weighted imaging, has brought the advantage of a comprehensive evaluation of pediatric patients without the risks inherent to ionizing radiation usually present in other conventional imaging methods. It is a rapid and sensitive method, particularly in pediatrics, for detecting and monitoring multifocal lesions in the body as a whole. In pediatrics, it is utilized for both oncologic and non-oncologic indications such as screening and diagnosis of tumors in patients with genetic syndromes, evaluation of disease extent and staging, evaluation of therapeutic response and post-therapy follow-up, evaluation of non neoplastic diseases such as multifocal osteomyelitis, vascular malformations and syndromes affecting multiple regions of the body. The present review was aimed at describing the major indications of whole-body MRI in pediatrics added of technical considerations.

Keywords: Magnetic resonance imaging; Whole-body MRI; Diffusion-weighted imaging; Pediatrics.

Portosystemic shunts are enlarged vessels that form collateral pathological pathways between the splanchnic circulation and the systemic circulation. Although their causes are multifactorial, portosystemic shunts all have one mechanism in common—increased portal venous pressure, which diverts the blood flow from the gastrointestinal tract to the systemic circulation. Congenital and acquired collateral pathways have both been described in the literature. The aim of this pictorial essay was to discuss the distinct anatomic and imaging features of portosystemic shunts, as well as to provide a robust method of differentiating between acquired portosystemic shunts and similar pathologies, through the use of illustrations and schematic drawings. Imaging of portosystemic shunts provides subclinical markers of increased portal venous pressure. Therefore, radiologists play a crucial role in the identification of portosystemic shunts. Early detection of portosystemic shunts can allow ample time to perform endovascular shunt operations, which can relieve portal hypertension and prevent acute or chronic complications in at-risk patient populations.

Keywords: Collateral circulation; Splanchnic circulation; Hypertension, portal/complications.

OBJECTIVE: To perform a quantitative analysis of the airways using automated software, in computed tomography images of patients with cystic fibrosis, correlating the results with spirometric findings. MATERIALS AND METHODS: Thirty-four patients with cystic fibrosis were studied—20 males and 14 females; mean age 18 ± 9 years—divided into two groups according to the spirometry findings: group I (n = 21), without severe airflow obstruction (forced expiratory volume in first second [FEV1] > 50% predicted), and group II (n = 13), with severe obstruction (FEV1 ≤ 50% predicted). The following tracheobronchial tree parameters were obtained automatically: bronchial diameter, area, thickness, and wall attenuation. RESULTS: On average, 52 bronchi per patient were studied. The number of bronchi analyzed was higher in group II. The correlation with spirometry findings, especially between the relative wall thickness of third to eighth bronchial generation and predicted FEV1, was better in group I. CONCLUSION: Quantitative analysis of the airways by computed tomography can be useful for assessing disease severity in cystic fibrosis patients. In patients with severe airflow obstruction, the number of bronchi studied by the method is higher, indicating more bronchiectasis. In patients without severe obstruction, the relative bronchial wall thickness showed a good correlation with the predicted FEV1.

Keywords: Cystic fibrosis; Tomography, X-ray computed; Airway remodeling/physiology.

Portal vein thrombosis refers to complete or partial obstruction of the portal venous system, in the intrahepatic or extrahepatic venous tract or even in the splenic or superior mesenteric veins. This common and potentially fatal condition can develop in various clinical contexts, especially those of liver cirrhosis, hepatocellular carcinoma, and other solid tumors. Certain characteristics, such as the time since the onset of the thrombus (acute or chronic), its biology (hematic or tumoral), the presence of collateral vessels, and the magnetic resonance imaging aspects, are important components of a thorough, careful analysis, as well as informing decisions regarding the appropriate therapeutic strategy. Here, we present a brief review of the anatomy of the portal venous system and a systematic approach to analyzing the condition, using a mnemonic (ABCD, for age, biology, collaterals, and diffusion). We discuss the various imaging methods and illustrate our discussion with images selected from the case files archived at our facility.

Keywords: Portal vein; Venous thrombosis; Hypertension, portal; Collateral circulation; Magnetic resonance imaging.