Balloon Valvuloplasty to Predict X-ray Projection Angles that are Perpendicular to Cardiovascular Structures: A TAVI Patient Feasibility Study

OBJECTIVES

The purpose of this work is to describe methods to measure the 3D angular orientation of cardiovascular structures based on a planar image of a valvuloplasty balloon. These methods facilitate X-ray beam alignment with respect to the anatomy of interest.

BACKGROUND

X-ray beam projections which are perpendicular to the long axis of cardiovascular structures are required to support interventional procedures, including transcatheter aortic valve implant (TAVI).

METHODS

During the TAVI procedure, the 3D angular orientation of the LVOT of 10 patients was measured from a single planar image of an aortic valvuloplasty balloon and the continuous range of X-ray projection angles which are aligned with the aortic valve plane were calculated (research method). Misalignment of the X-ray beam and TAVI valve frame was measured from images of the deployed valve. The accuracy of the research method was compared to clinical standard method to determine appropriate X-ray projection angles, which utilized CT and aortography.

RESULTS

Using the clinical standard method, the median misalignment of the X-ray beam and TAVI valve frame was 8.6° (range 2.6° to 21°). Misalignment was reduced to 2.5° (range 0° to 10°) using the research method.

CONCLUSIONS

The 3D angular orientation of cardiovascular structures can be measured accurately from a single X-ray projection image of a known cardiovascular device contained within the anatomy of interest. For TAVI procedures, improved X-ray beam alignment may help facilitate procedural success. © 2016 Wiley Periodicals, Inc.

Positron emission tomography within a magnetic field using photomultiplier tubes and lightguides

The spatial resolution of positron emission tomography (PET) improves when positron annihilation takes place in a strong magnetic field. In a magnetic field, the Lorentz force restricts positron range perpendicular to the field. Since positron annihilation occurs closer to its point of origin, the positron annihilation point spread function decreases. This was verified experimentally by measuring the spread function of positron annihilation from a 500 mm 68Ge bead imbedded in tissue-equivalent wax. At 5 T the spread function full width at half maximum (FWHM) and the full width at tenth maximum (FWTM) decrease by a factor of 1.42 and 2.09, respectively. Two NaI(Tl) scintillation crystals that interface to a pair of photomultiplier tubes (PMTS) through long lightguides detect positron annihilation at zero field and 5.0 T. Photomultiplier tubes, inoperable in strong magnetic fields, are functional if lightguides bring the photons produced by scintillators within the field to a minimal magnetic field. These tests also demonstrate techniques necessary for combining magnetic resonance imaging (MRI) and PET into one scanner.

Exclusive breast-feeding of newborns among married women in the United States: the National Natality Surveys of 1969 and 1980

Questions about infant feeding practices after birth were included in 1969 and 1980 National Natality Surveys (NNS). At 3-6 mo postpartum, NNS questionnaires were mailed to mothers of live infants born in wedlock, and responses were weighted to permit national estimates. Based on the NNS, the proportion of women who were exclusively breast-feeding newborns in the United States was significantly lower in 1969 (19% of white women, 9% of black women) compared with 1980 (51% of white women, 25% of black women). In 1969, the highest percentages of exclusive breast-feeding were observed among white women less than or equal to 34 yr, of parity less than or equal to 3 and greater than 7, and of higher than lower socioeconomic groups; and among black women greater than or equal to 30 yr, of parity greater than or equal to 4, and of lower than higher socioeconomic groups. Among women in both races in 1980, more primiparae than multiparae and the more highly educated were breast-feeding. More white than black women exclusively breast-fed within each birthweight and each sociodemographic characteristic in 1980; therefore, the racial differences remained across these factors. These findings are compared with results of the Ross Laboratories surveys of infant feeding.

Cesarean section and subsequent fertility: results from the 1982 National Survey of Family Growth

The purpose of this article was to examine the question of fertility after a cesarean section. The study design is that of a retrospective cohort study with matched pairs, using the cross-sectional interview data of the 1982 National Survey of Family Growth. The subsequent fertility of 406 women who had had their first delivery by cesarean section is compared with that of 406 matched control women. Using any of several measures, women who had had a cesarean section had lower fertility. The difference in fertility seemed to result largely from difficulties in having children after a cesarean section, rather than lessened desire for children. Sterilizations were more frequent and performed earlier among women who had had a cesarean section than among the control women.

Statistical discrimination among vocalizations of individual squirrel monkeys (Saimiri sciureus)

Discriminant analysis was used to distinguish statistically between the chuck vocalizations of individual squirrel monkeys. A unique combination of values of six structural parameters characterized the chucks of each of 5 individuals, permitting reliable identification of sources of chuck vocalizations on the basis of chuck structures alone. Certain parameters were found to be nearly invariant within individual monkeys, while others were quite variable within and between individuals. We propose that this technique be used in retrospective classification of vocalizations by source, when observational identification of the sources of all vocalizations in a rapid sequence is not possible.