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

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

Magnetic resonance imaging has become the first choice imaging method for the evaluation of the joints due to its exceptional tissue differentiation, high resolution, multiplanar images and kinematics studies. The knee is probably the most common joint evaluated by magnetic resonance imaging and the knowledge of anatomy, physiology and imaging features is essential for an accurate interpretation of these studies. However, anatomical structures that are only observed sporadically, normal variants and artifacts may sometimes make it difficult to interpret these examinations. The purpose of this article is to review the most frequent pitfalls of magnetic resonance imaging of the knee, discuss their causes and how to avoid them.

Keywords: Magnetic resonance imaging. Knee. Pitfalls. Errors. Pseudolesions.

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.

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.

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.

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 assess the feasibility and reliability of apparent diffusion coefficient (ADC) measurements of normal adrenal glands. MATERIALS AND METHODS: This was a retrospective study involving 32 healthy subjects, divided into two groups: prepubertal (PreP, n = 12), aged from 2 months to 12.5 years (4 males; 8 females); and postpubertal (PostP, n = 20), aged from 11.9 to 61 years (5 males; 15 females). Diffusion-weighted magnetic resonance imaging (DW-MRI) sequences were acquired at a 1.5 T scanner using b values of 0, 20, 500, and 1000 s/mm². Two radiologists evaluated the images. ADC values were measured pixel-by-pixel on DW-MRI scans, and automatic co-registration with the ADC map was obtained. RESULTS: Mean ADC values for the right adrenal glands were 1.44 × 10^–3 mm²/s for the PreP group and 1.23 × 10^–3 mm²/s for the PostP group, whereas they were 1.58 × 10^–3 mm²/s and 1.32 × 10^–3 mm²/s, respectively, for the left glands. ADC values were higher in the PreP group than in the PostP group (p < 0.05). Agreement between readers was almost perfect (intraclass correlation coefficient, 0.84–0.94; p < 0.05). CONCLUSION: Our results demonstrate the feasibility and reliability of performing DW-MRI measurements of normal adrenal glands. They could also support the feasibility of ADC measurements of small structures.

Keywords: Adrenal glands; Diffusion magnetic resonance imaging; Magnetic resonance imaging.

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.

Active surveillance (AS) is an important strategy to avoid overtreatment of prostate cancer (PCa) and has become the standard of care for low-risk patients. The role of magnetic resonance imaging (MRI) in AS has expanded due to its ability to risk stratify patients with suspected or known PCa, and MRI has become an integral part of the AS protocols at various institutions. A negative pre-biopsy MRI result is associated with a very high negative predictive value for a Gleason score ≥ 3+4. A positive MRI result in men who are otherwise eligible for AS has been shown to be associated with the presence of high-grade PCa and therefore with ineligibility. In addition, MRI can be used to guide and determine the timing of per-protocol biopsy during AS. However, there are several MRI-related issues that remain unresolved, including the lack of a consensus and guidelines; concerns about gadolinium deposition in various tissues; and increased demand for higher efficiency and productivity. Similarly, the need for the combined use of targeted and systematic sampling is still a matter of debate when lesions are visible on MRI. Here, we review the current AS guidelines, as well as the accepted roles of MRI in patient selection and monitoring, the potential uses of MRI that are still in question, and the limitations of the method.

Keywords: Prostatic neoplasms/diagnostic imaging; Watchful waiting/methods; Magnetic resonance imaging/methods; Neoplasms/diagnostic imaging.

OBJECTIVE: To profile the use of educational materials by radiologists and radiology residents in Brazil. MATERIALS AND METHODS: This was a cross-sectional, descriptive, observational study in which an electronic questionnaire was sent via email to physicians working in the field of radiology. The questionnaire contained questions regarding the profile, education, and place of work of the physicians, as well as their access to educational resources and the types of educational materials they used most. RESULTS: The questionnaire was completed by 265 physicians. The mean age of the respondents was 38.2 years. Of the 265 respondents, 212 (80.0%) worked with ultrasound, 206 (77.7%) worked with computed tomography, 170 (64.2%) were board-certified, 166 (62.6%) were male, 174 (65.7%) worked at private facilities, and 167 (63.0%) had no academic affiliation. The mean weekly total study time was 9.6 h (median, 6 h), being higher among physicians in training, among those who worked at public facilities, and among those who worked at teaching hospitals. Regarding the device employed in order to access educational materials, there was a trend toward greater use of computers, which were employed by 65.3%. The majority of the respondents (61.9%) chose to access educational materials that were free of charge, the most common sources being websites, eBooks, and online journals. CONCLUSION: Electronic and digital resources are the main means of access to educational materials used by radiologists in Brazil, the most commonly used resources being web sites, eBooks, and online journals.

Keywords: Radiology; Teaching materials; Education, continuing; Multimedia.