Normal cerebral perfusion measurements using arterial spin labeling: reproducibility, stability, and age and gender effects.

Before meaningful conclusions can be drawn from clinical measures of cerebral blood perfusion, the precision of the measurement must be determined and set in the context of inter- and intrasubject sources of variability. This work establishes the reproducibility of perfusion measurements using the noninvasive MRI technique of continuous arterial spin labeling (CASL). Perfusion was measured in 34 healthy normal subjects. Intersubject variability was assessed, and age and gender contributions were estimated. Intersubject variation was found to be large, with up to 100% perfusion difference for subjects of the same age and gender. Repeated measurements in one subject showed that perfusion remains remarkably stable in the short term when compared with intersubject variation and the large capacity for perfusion change in the brain. A significant decrease in the ratio of gray-matter to white-matter perfusion was found with increasing age (0.79% per year (P < 0.0005)). This appears to be due mainly to a reduction in gray-matter perfusion, which was found to decrease by 0.45% per year (P = 0.04). Regional analysis suggested that the gray-matter age-related changes were predominantly localized in the frontal cortex. Whole-brain perfusion was 13% higher (P = 0.02) in females compared to males.     

In situ saphenous vein bypass grafts: angiographic evaluation and interventional repair of complications

In situ saphenous vein grafts are being used with increasing frequency for bypass procedures involving the femoral and popliteal arteries. Complications of these procedures include anastomotic stenoses and persistent arteriovenous fistulae that may result in failure of the graft. Balloon angioplasty and embolotherapy with detachable balloons were employed successfully in three or four recent cases of patients with complications from in situ grafts. Tailored angiography is essential for evaluating in situ grafts, and interventional techniques are extremely useful for managing complications.     

Acute herniation through a posterolateral diaphragmatic (Bochdalek) hernia in an adult

Acute herniation through a posterolateral diaphragmatic defect is rare. A case is presented in which herniation took place after the sudden inversion of a 16-year old youth. Its aetiology, presentation, diagnosis and treatment are discussed.     

Biochemical composition of amniotic fluid and extraembryonic coelomic fluid in the first trimester of pregnancy.

OBJECTIVE: To determine the biochemical composition of amniotic fluid and extraembryonic coelomic fluid between 8 and 12 weeks gestation. DESIGN: Prospective observational study. SUBJECTS: 40 women with a normal pregnancy between 7 and 12 weeks gestation having termination of pregnancy. INTERVENTIONS: Before termination the women had a transvaginal ultrasound guided amniocentesis. Pure samples of amniotic fluid and extraembryonic coelomic fluid were obtained from each woman and standard biochemical variables were measured in each fluid sample immediately after collection. RESULTS: Levels of sodium, potassium and bicarbonate were significantly higher in amniotic fluid whilst chloride, urea, bilirubin, protein, albumin, glucose, creatinine, calcium and phosphate were present in higher concentrations in extraembryonic coelomic fluid. All differences in concentration were significant (P less than 0.05; unpaired t-test). No relation was demonstrated between electrolyte concentrations in amniotic fluid or coelomic fluid and stage of gestation. CONCLUSIONS: Amniotic fluid and extraembryonic coelomic fluid have a widely differing biochemical composition. The biological significance of these differences remains unexplained.     

Erythropoietin levels in amniotic fluid and extraembryonic coelomic fluid in the first trimester of pregnancy.

OBJECTIVE: The aim was to measure erythropoietin levels in amniotic fluid and extraembryonic coelomic fluid from 7-12 weeks' gestation. SUBJECTS: Twenty healthy women with ultrasonographically normal first trimester pregnancies prior to surgical termination. METHODS: Paired samples of amniotic fluid and extraembryonic coelomic fluid were collected by transvaginal ultrasound guided needling. Erythropoietin was measured in both pregnancy fluids using a radioimmunoassay. RESULTS: There was a highly significant difference between erythropoietin levels in extraembryonic coelomic fluid (median level 15.45 mU/ml; range 6.8-32.1 mU/ml) and those in amniotic fluid (median 5.0 mU/ml; range < 5.0-5.8 mU/ml) (P < 0.0001; Mann-Whitney U-test). The levels of erythropoietin in maternal serum (median 15.4 mU/ml; range 5.6-29.4 mU/ml) were similar to those in the extra-embryonic coelom (P = 0.81; Mann-Whitney U-test). No relation was demonstrated between erythropoietin levels in amniotic fluid or coelomic fluid and stage of gestation. CONCLUSION: High levels of erythropoietin in coelomic fluid suggests that the hormone is involved in the process of human extraembryonic erythropoiesis. The exact regulatory role remains unknown.