Quantification of in-plane motion of the coronary arteries during the cardiac cycle: Implications for acquisition window duration for MR flow quantification

Motion of the coronary arteries during the heart cycle can result in image blurring and inaccurate flow quantification by MR. This condition applies particularly for longer acquisition windows that are typical of breath-hold coronary flow measurements. To determine the sensitivity of the technique to in-plane motion of different coronary arteries, the temporal variation in coronary position was measured in a plane perpendicular to the proximal portion of the vessel. The results indicated the presence of substantial displacement of the coronary arteries within the cardiac cycle, with a magnitude of motion approximately twice as large for the right as for the left coronary arteries. An estimation of the resulting vessel blurring was calculated, showing that the duration of the acquisition window for high spatial resolution coronary flow acquisitions should be less than 25 to 120 msec, depending on the specific coronary artery studied. In addition, these data specify optimal acquisition window placement for high resolution coronary angiography.     

Research fellowship in behavioral AIDS research

Announcement

Research fellowship in behavioral AIDS research     

Bromodeoxyuridine tablet methodology for in vivo

5-Bromodeoxyuridine (BrdU) tablets with different physical characteristics are useful in a wide variety of studies requiring detection of DNA replication in vivo. These tablets can effect a high substitution of BrdU in DNA, thereby permitting sister chromatid differentiation in chromosomes stained with 33258 Hoechst alone or in conjunction with Giemsa. Baseline and cyclophosphamide-induced in vivo sister chromatid exchange frequencies in mouse spleen, marrow, and thymus were measured and found to be significantly greater than those in spermatogonia. Sister chromatid exchange analysis was also extended to mouse liver and to Chinese hamster and Armenian hamster marrow cells. Sister chromatid differentiation was observed in Armenian hamster meiotic tissue, and evidence for interhomolog chromatid exchange obtained.     

Fibrolamellar Carcinoma of Liver: A Primary Malignant Oncocytic Carcinoid?

Immunohistochemical and ultrastructural findings in two cases of fibrolamellar carcinoma of the liver and two cases of hepatocellular carcinoma of the common histologic type are described. Ultrastructural examination of both cases of fibrolamellar carcinoma revealed the presence of neurosecretory (NS) granules which were sparse in some cells and abundant in others. Many of the tumor cells had a distinct oncocytic appearance with abundant mitochondria. A portion of the glutaraldehyde-fixed neoplasm was processed for the uranaffin reaction (an ultrastructural cytochemical stain specific for the NS granules of neuroendocrine tissue). Abundant uranaffin-positive granules were found in the neoplastic cells of both cases of fibrolamellar carcinoma, whereas no uranaffin-positive granules were found in hepatocellular carcinoma of the common histologic type. There was no statistical difference in the mean diameter of the uranaffin-positive granules measured from both cases. Immunohisto-chemistry revealed the presence of neuron-specific enolase (NSE) and serotonin in one of the two cases of fibrolamellar carcinoma and no NSE staining in two cases of hepatocellular carcinoma of the common histologic type. These findings suggest that some liver tumors presenting histologically as fibrolamellar carcinoma may be neuroendocrine in nature.