MR technology: effect of even-echo rephasing on calculated T2 values and T2 images

In multiple spin-echo image sequences of blood flow, the "even-echo" phenomenon produces an absolute increase in signal magnitude from first- to second-echo images of normal vessels harboring slow flow. Distinguishing this from the apparent relatively high signal intensity seen on second-echo images in pathologic foci of stationary tissue is important to the diagnostician. Selected case material containing two tissue types was reviewed retrospectively: tissues known to harbor slow flow, such as normal veins and venous sinuses and vascular malformations, and tissues that have long transverse (T2) relaxation times and appear as intense structures on second-echo images, such as neoplasms, infarcts, and regions of demyelination. Calculations of T2 parameters were made by computer for defined regions of interest. T2 images were also generated. Visual inspection of the acquired images did not reliably distinguish increased intensity due to even-echo rephasing from the relative changes between adjacent tissues seen on second-echo images. More definitive differentiation of the even-echo phenomenon was provided by calculated values of T2 and computer-synthesized T2 images representing acquired intensity data of two-echo sequences. The synthesized images were especially useful when stationary tissue with lengthened T2 values was adjacent to or in proximity to vessels or vascular lesions. A five spin-echo image sequence was valuable for separating slow flow from stationary tissue by a technique of synthesizing T2-difference images using three consecutive echoes.     

Microenvironmental exposure to mercury vapor

Work area and breathing zone samples were collected in a factory utilizing metallic mercury and analyzed for mercury vapor content. Breathing zone samples averaged several fold higher in concentration than concurrent area samples, reflecting a "microenvironmental" exposure to mercury vapor, presumably from contaminated clothing and hands. Blood and corrected total urine mercury values correlated well with the average microenvironmental exposure level for each worker. Measurements of unbound mercury in urine samples were sensitive at picking up minimal exposures. Excessive amounts of unbound mercury were not found in the urine, even with wide day-to-day swings in microenvironmental mercury vapor levels, suggesting that the human body can adapt to a chronic, moderate exposure to mercury vapor.     

The influence of cytoreductive surgery on recurrence-free interval and survival in small-volume stage III epithelial ovarian cancer: a Gynecologic Oncology Group study.

Gynecologic Oncology Group Protocol 52, a randomized trial of cisplatin and cyclophosphamide with or without doxorubicin in "optimal" Stage III epithelial ovarian cancer, failed to demonstrate a significant difference in the outcome in 349 evaluable patients. Additional review of the records was carried out to determine the influence of cytoreductive surgery on survival. Since eligibility for the study was the presence of residual cancer of 1 cm or less, the influence of cytoreductive surgery could be evaluated by comparing outcome in patients presenting with large-volume extrapelvic disease, but who were cytoreduced to small-volume disease. Factors evaluated were age, cell type, grade, size, and location of disease at exploration, size, and location of residual disease after cytoreduction, number of residual nodules, ascites, type of surgery, blood loss, and hospital days. Univariate analysis revealed that age, size of residual disease, mucinous or clear cell histologic type, histologic grade, and number of residual lesions were significant prognostic factors. By univariate analysis patients found to have extrapelvic disease of 1 cm or less had a better recurrence-free interval and survival than those patients with large-volume disease who were cytoreduced to disease of 1 cm or less. Multivariate analysis revealed that older age, histologic grades 2 and 3, and 20 or more residual lesions were unfavorable. The volume of initial extrapelvic disease remained significant when gross disease was present in the omentum and in other extrapelvic sites. This study failed to prove the hypothesis that initial cytoreductive surgery would allow a patient presenting with large-volume ovarian cancer to have the same chance for survival as a patient found to have small-volume disease. Factors other than cytoreductive surgery are important in predicting survival.