Gastrointestinal bleeding is a common problem encountered in the emergency department and in the primary care setting. Acute or overt gastrointestinal bleeding is visible in the form of hematemesis, melena or hematochezia. Chronic or occult gastrointestinal bleeding is not apparent to the patient and usually presents as positive fecal occult blood or iron deficiency anemia. Obscure gastrointestinal bleeding is recurrent bleeding when the source remains unidentified after upper endoscopy and colonoscopic evaluation and is usually from the small intestine. Accurate clinical diagnosis is crucial and guides definitive investigations and interventions. This review summarizes the overall diagnostic approach to gastrointestinal bleeding and provides a practical guide for clinicians.

Purpose To determine the diagnostic accuracy of magnetic resonance (MR) imaging for differentiating synovial patterns in patients with total knee arthroplasty (TKA), whether diagnostic accuracy differs in index versus revision TKA, and interobserver and intraobserver reliability for assessment of synovial patterns at MR imaging. Materials and Methods This retrospective cross-sectional study included 108 consecutive patients with TKAs who underwent MR imaging within 1 year prior to revision surgery from 2012 to 2014. Institutional review board approval was obtained, with waiver of the need to obtain informed consent. MR images were reviewed, and cases were qualitatively categorized by the appearance of the synovium as one of the following: frondlike and hypertrophied (particle-induced synovitis), lamellated and hyperintense (infection), and a homogeneous effusion with the signal intensity of fluid (nonspecific synovitis). The MR imaging appearance was compared with surgical and microbiology reports as the reference standard to determine the sensitivity, specificity, and positive and negative predictive values for the index TKA and revision TKA cohorts. Results For all patients combined, MR imaging had 0.907-0.930 sensitivity and 0.723-0.738 specificity for a surgical diagnosis of complications related to polyethylene wear (including osteolysis and loosening); 0.652-0.783 sensitivity and 0.976-0.988 specificity for infection; and 0.643-0.667 sensitivity and 0.894-0.939 specificity for stiffness, instability, and nonspecific pain. Diagnostic accuracy was higher in the index TKA cohort than in the revision TKA cohort. Interobserver and intraobserver reliabilities were almost perfect (κ = 0.82 and κ = 0.83, respectively). Conclusion MR imaging can help distinguish qualitative differences in the appearance of the synovium in TKA between particle-induced synovitis, infection, and nonspecific synovitis, with almost perfect interobserver and intraobserver reliability. Diagnostic accuracy is higher for index TKA than for revision TKA. RSNA, 2016.

Caution should be employed when inserting anchors for labral refixation, particularly in anterior and medial locations (2-4 o'clock), as articular surface and psoas tunnel perforation may occur at a rate higher than previously anticipated. Portal selection does not appear to influence these outcomes.

Femoroacetabular impingement (FAI) refers to a condition characterized by impingement of the femoral head–neck junction against the acetabular rim, often due to underlying osseous and/or soft tissue morphological abnormalities. It is a common cause of hip pain and limited range of motion in young and middle-aged adults. Hip preservation surgery aims to correct the morphological variants seen in FAI, thereby relieving pain and improving function, and potentially preventing early osteoarthritis. The purpose of this article is to review the mechanisms of chondral and labral injury in FAI to facilitate an understanding of patterns of chondrolabral injury seen on MRI. Preoperative MRI evaluation of FAI should include assessment of osseous morphologic abnormalities, labral tears, cartilage status, and other associated compensatory injuries of the pelvis. As advanced chondral wear is the major relative contraindication for hip preservation surgery, MRI is useful in the selection of patients likely to benefit from surgery.Teaching points • The most common anatomical osseous abnormalities predisposing to FAI include cam and pincer lesions.• Morphological abnormalities, labral lesions, and cartilage status should be assessed.• In cam impingement, chondral wear most commonly occurs anterosuperiorly.• Pre-existing advanced osteoarthritis is the strongest predictor of poor outcomes after FAI surgery.• Injury to muscles and tendons or other pelvic structures can coexist with FAI.

With advances in implant technology, total ankle arthroplasty (TAA) has become an increasingly popular alternative to arthrodesis for the management of end-stage ankle arthritis. However, reports in the literature do not focus on the imaging features of TAA. Through a literature review, we demonstrate basic design features of the current ankle arthroplasty system, and the normal and abnormal postoperative imaging features associated with such devices. Pre- and postoperative evaluations of ankle arthroplasty mainly include radiography; in addition, computed tomography and magnetic resonance imaging provide further characterization of imaging abnormalities. Familiarization with multimodal imaging features of frequent procedural complications at various postoperative intervals is important in radiological practice.

The magnitude of frondlike hypertrophied synovitis on MRI is significantly associated with polyethylene surface damage in patients who undergo revision TKA. The finding of severe frondlike synovitis on MR images of patients with TKA should raise the possibility of polyethylene surface damage. However, time since implantation is a stronger predictor of surface damage.

The shape of the polyethylene tibial insert varied with the design. Polyethylene tibial insert abnormalities seen on MRI included displacement and fracture. MRI distinguishes various designs of polyethylene tibial inserts and can show associated abnormalities.

We sought to evaluate the interobserver and intraobserver reliability of radiographs and magnetic resonance imaging (MRI) for grading of osteoarthritis in patients with scapholunate advanced collapse (SLAC) and scaphoid nonunion advanced collapse (SNAC), and to determine whether MRI is more likely than radiographs to detect carpal osteoarthritis. Radiographs and MR studies of 46 patients with SLAC and SNAC arthritis were reviewed by two hand surgeons and two radiologists and were graded according to severity of osteoarthritis at seven carpal joints. Interobserver and intraobserver reliability was assessed using a weighted kappa analysis. Odds ratios were calculated to compare the likelihood of MRI versus radiographs in the determination of moderate or severe osteoarthritis. Measures of reliability were higher for MRI than radiographs. For radiographic assessment of all patients combined, interobserver agreement was moderate and intraobserver agreement was also moderate. For MRI, interobserver agreement was substantial and intraobserver agreement was almost perfect. In all joints combined for patients with SLAC and SNAC, MRI was 2.42 times more likely to demonstrate moderate osteoarthritis compared with radiographs. In patients with SLAC, MRI was 11.73 times more likely than radiographs to show moderate osteoarthritis at the radiolunate joint. In patients with SNAC, there was no difference in demonstration of moderate osteoarthritis on MRI compared with radiographs. Carpal osteoarthritis can be more reliably assessed on MRI than radiographs. MRI is more sensitive at demonstrating moderate changes of osteoarthritis than radiographs, especially at the radiolunate joint in patients with SLAC arthritis. This has implications for surgical management of SLAC/SNAC arthritis and preoperative planning. MRI should be included in the diagnostic workup and evaluation of patients with SLAC and SNAC arthritis. Diagnostic III.