Intracranial MRA: single volume vs. multiple thin slab 3D time-of-flight acquisition.

Single volume three-dimensional (3D) time-of-flight (TOF) MR angiography is the most commonly used noninvasive method for evaluating the intracranial vasculature. The sensitivity of this technique to signal loss from flow saturation limits its utility. A recently developed multislab 3D TOF technique, MOTSA, is less affected by flow saturation and would therefore be expected to yield improved vessel visualization. To study this hypothesis, intracranial MR angiograms were obtained on 10 volunteers using three techniques: MOTSA, single volume 3D TOF using a standard 4.9 ms TE (3D TOFA), and single volume 3D TOF using a 6.8 ms TE (3D TOFB). All three sets of axial source images and maximum intensity projection (MIP) images were reviewed. Each exam was evaluated for the number of intracranial vessels visualized. A total of 502 vessel segments were studied with each technique. With use of the MIP images, 86% of selected vessels were visualized with MOTSA, 64% with 3D TOFA (TE = 4.9 ms), and 67% with TOFB (TE = 6.8 ms). Similarly, with the axial source images, 91% of selected vessels were visualized with MOTSA, 77% with 3D TOFA (TE = 4.9 ms), and 82% with 3D TOFB (TE = 6.8 ms). There is improved visualization of selected intracranial vessels in normal volunteers with MOTSA as compared with single volume 3D TOF. These improvements are believed to be primarily a result of decreased sensitivity to flow saturation seen with the MOTSA technique. No difference in overall vessel visualization was noted for the two single volume 3D TOF techniques.

Immunosuppressive activity and alpha interferon concentrations in human embryo culture media as an index of potential for successful implantation.

OBJECTIVE: To evaluate potential correlations between establishment of pregnancy and immunosuppressive activity secreted by the preimplantation embryo. DESIGN: To evaluate immunosuppressive activity, supernatants from preimplantation embryos were assessed for their ability to inhibit lymphocyte proliferation. Additionally, alpha interferon concentrations were also measured in these supernatants. We compared these parameters from embryo culture supernatants of women who did and did not achieve pregnancy after in vitro fertilization (IVF). Immunosuppression was assessed using a lymphocyte proliferation assay with concanavalin A (Con A) and phytohemagglutinin (PHA) as mitogens. SETTING: In vitro fertilization program at the University of Utah Medical Center. PARTICIPANTS: Couples less than 40 years of age, with normal semen quality and bilateral tubal obstruction. RESULTS: Immunosuppression calculated using the stimulation index (mean +/- SEM) in pregnant and nonpregnant women, respectively, were: Con A: 43.9 +/- 3.9 versus 19.1 +/- 10.1, P less than 0.04. PHA: 23.6 +/- 5.6 versus 12.5 +/- 12.8, P less than 0.02. Alpha interferon levels (mean +/- SD) in pregnant and nonpregnant women were not significantly different: 23.98 +/- 9.6 U/mL versus 24.79 +/- 2.5 U/mL. CONCLUSIONS: We conclude that pre-embryos with the capacity for successful implantation secrete greater amounts of immunosuppressive factors than those destined not to implant, as measured by Con A and PHA lymphocyte proliferation assays. Refinement of assay techniques and identification of the substances involved could have significant impact on IVF programs.