A motive for the use of a posterior approach in shoulder arthography: ventral leakage of contrast medium.

BACKGROUND: Some orthopedic surgeons request a posterior approach for shoulder magnetic resonance (MR) arthrography, especially in patients with anterior shoulder instability, to avoid interpretive difficulties in differentiating anterior extraarticular contrast injection when using an anterior approach from ventral leakage of contrast. PURPOSE: To determine the occurrence of ventral leakage of contrast in shoulder MR arthrography when using a posterior approach. MATERIAL AND METHODS: Retrospectively, we included 73 consecutive patients who underwent shoulder MR arthrography (1.0 Tesla) using the posterior approach. Three unsuccessful procedures were excluded. Ventral leakage of contrast, defined as contrast seen around the musculus subscapularis without distention of the posterior capsule, was recorded. Descriptive statistics were used. RESULTS: Seventy shoulders were included. Forty-one left shoulders were involved (59%). Mean age of patients was 49 years (range, 17-76 years). Thirty-five patients were women (50%). Ventral leakage of contrast was seen in 12 shoulders (17%). CONCLUSION: As ventral leakage of contrast was seen in a substantial number of cases when using a posterior approach in shoulder MR arthrography, the use of a posterior approach is advised to avoid misinterpretation of ventral contrast leakage with accidental extra articular contrast injection, and to increase confidence in the final radiological diagnosis.

Neutralizing B cell response in measles.

Co-evolving mechanisms of immune clearance and of immune suppression are among the hallmarks of measles. B cells are major targets cells of measles virus (MV) infection. Virus interactions with B cells result both in immune suppression and a vigorous antibody response. Although antibodies fully protect against (re)infection, their importance during the disease and in the presence of a potent cellular response is less well understood. Specific serum IgM appears with onset of rash and confirms clinical diagnosis. After isotype switching, IgG1 develops and confers life-long protection. The most abundant antibodies are specific for the nucleoprotein, but neutralizing and protective antibodies are solely directed against the two surface glycoproteins, the hemagglutinin and the fusion protein. Major neutralizing epitopes have been mapped mainly on the hemagglutinin protein with monoclonal antibodies, producing an increasingly comprehensive map of functional domains.