Receiver operating characteristic (ROC) curve analysis of transrectal ultrasonographic prostate cancer detection.

PURPOSE: To provide an overview of receiver operating characteristics (ROC) curve theory and create an ROC curve describing transrectal ultrasound (TRUS) detection of prostate cancer (PCa). METHODS: One hundred thirty-two patients with either an abnormal digital rectal exam (DRE) or a prostate-specific antigen (PSA) above 4 ng/ml or both underwent TRUS and biopsy of the peripheral zone (PZ) of each quadrant. ROC software was used to create an ROC curve. RESULTS: One hundred seventy-nine of 528 quadrants (34%) harbored PCa. The performance of TRUS in detection of PCa as defined by the area below the ROC is 0,809. CONCLUSIONS: Future investigators are encouraged to employ ROC analysis of TRUS to permit more meaningful comparisons of performance.

Anterior cruciate ligament tear: prospective evaluation of diagnostic accuracy of middle- and high-field-strength MR imaging at 1.5 and 0.5 T.

PURPOSE: To compare the diagnostic efficacy of current-generation middle- and high-field-strength magnetic resonance (MR) imagers in the diagnosis of anterior cruciate ligament (ACL) tears. MATERIALS AND METHODS: In 114 of 230 patients referred for knee imaging, MR imaging at 0.5 and 1.5 T was performed with identical sequences but with a slightly longer total imaging time and bandwidth optimization at 0.5 T. Radiologists were blinded to diagnosis and field strength. Sensitivity, specificity, and accuracy were determined, and ACL tear was confirmed by means of arthroscopy and pathology. RESULTS: There was no difference between the field strengths in accuracy, sensitivity, or specificity for the diagnosis of ACL tears in 86 patients with disrupted ACLs and 28 patients with intact ACLs. Accuracy for all ACL tears was 90% at 0.5 T and 91% at 1.5 T. Similarly, there were no differences in diagnosis of meniscal tears (79 with, 149 without) or posterior cruciate ligament tears (seven with, 107 without). CONCLUSION: Higher field strength does not confer higher accuracy in the diagnosis of ACL tears at MR imaging.

MR imaging field strength: prospective evaluation of the diagnostic accuracy of MR for diagnosis of multiple sclerosis at 0.5 and 1.5 T.

PURPOSE: To compare the diagnostic efficacy of middle-field-strength and high-field-strength magnetic resonance (MR) imaging in diagnosis of multiple sclerosis. MATERIALS AND METHODS: One hundred thirty-two patients with suspected multiple sclerosis underwent MR imaging at 0.5 and 1.5 T. Imaging parameters were identical except for band width optimization at middle field strength. Images were interpreted by radiologists expert in MR imaging who were blinded to diagnosis and field strength. The diagnosis of multiple sclerosis was made by experienced neurologists, and indeterminate cases and patients without clinical evidence of multiple sclerosis were followed up for 6 months to 1 year. RESULTS: There was no difference in accuracy, sensitivity, or specificity between scanners in the diagnosis of multiple sclerosis or white matter disease. Equal numbers of lesions were detected at both field strengths in all parts of the brain. Image quality was always good or adequate at middle field strength. CONCLUSION: Higher field strength does not confer higher accuracy in the diagnosis of multiple sclerosis with current-generation MR imagers.

Two siblings with recurrent cardiorespiratory arrest: Munchausen syndrome by proxy or child abuse?

The terms "Munchausen syndrome by proxy" or "Polle syndrome" have been used to describe children who are victims of parentally induced or fabricated illness. This report gives case histories of two siblings (a 7-month-old girl and a 4-year-old boy) with recurrent episodes of cardiorespiratory arrest that were induced by a mother who skillfully resuscitated the children and who demonstrated model parental behavior. Polygraphic monitoring with hidden camera was used to determine that the episodes of cardiorespiratory arrest were parentally induced in the infant. The 4-year-old sibling had previously undergone multiple diagnostic and surgical procedures. After the diagnosis was made in the infant, and the mother was no longer permitted to be alone with the children, neither child had further episodes. A psychologic profile of the mother is presented, and special features of these two and other cases in the literature are reviewed. These cases represent a form of child abuse. A parentally induced illness should be considered in the differential diagnosis of unusual illnesses with bizarre features, even when the parent's behavior appears exemplary.