Volume rendering quantification algorithm for reconstruction of CT volume-rendered structures: Part I. Cerebral arteriovenous malformations.

Volume rendering is a visualization technique that has important applications in diagnostic radiology and in radiotherapy but has not achieved widespread use due, in part, to the lack of volumetric analysis tools for comparison of volume rendering to conventional visualization techniques. The volume rendering quantification algorithm (VRQA), a technique for three-dimensional (3-D) reconstruction of a structure identified on six principal volume-rendered views, is introduced and described. VRQA involves three major steps: 1) preprocessing of the partial surfaces constructed from each of six volume-rendered images; 2) merging these processed partial surfaces to define the boundaries of a volume; and 3) computation of the volume of the structure from this boundary information. After testing on phantoms, VRQA was applied to CT data of patients with cerebral arteriovenous malformations (AVM's). Because volumetric visualization of the cerebral AVM is relatively insensitive to operator dependencies, such as the choice of opacity transfer function, and because precise volumetric definition of the AVM is necessary for radiosurgical treatment planning, it is representative of a class of structures that is ideal for testing and calibration of VRQA. AVM volumes obtained using VRQA are intermediate to those obtained using axial contouring and those obtained using CT-correlated biplanar angiography (two routinely used visualization techniques for treatment planning for AVM's). Applications and potential expansions of VRQA are discussed.

Effect of HIV reporting by name on use of HIV testing in publicly funded counseling and testing programs.

CONTEXT: Policies requiring confidential reporting by name to state health departments of persons infected with the human immunodeficiency virus (HIV) have potential to cause some of them to avoid HIV testing. OBJECTIVE: To describe trends in use of HIV testing services at publicly funded HIV counseling and testing sites before and after the implementation of HIV reporting policies. DESIGN AND SETTING: Analysis of service provision data from 6 state health departments (Louisiana, Michigan, Nebraska, Nevada, New Jersey, and Tennessee) 12 months before and 12 months after HIV reporting was introduced. MAIN OUTCOME MEASURE: Percent change in numbers of persons tested at publicly funded HIV counseling and testing sites after implementation of confidential HIV reporting by risk group. RESULTS: No significant declines in the total number of HIV tests provided at counseling and testing sites in the months immediately after implementation of HIV reporting occurred in any state, other than those expected from trends present before HIV reporting. Increases occurred in Nebraska (15.8%), Nevada (48.4%), New Jersey (21.3%), and Tennessee (62.8%). Predicted decreases occurred in Louisiana (10.5%) and Michigan (2.0%). In all areas, testing of at-risk heterosexuals increased in the year after HIV reporting was implemented (Louisiana, 10.5%; Michigan, 225.1 %; Nebraska, 5.7%; Nevada, 303.3%; New Jersey, 462.9%; Tennessee, 603.8%). Declines in testing occurred among men who have sex with men in Louisiana (4.3%) and Tennessee (4.1%) after HIV reporting; testing increased for this group in Michigan (5.3%), Nebraska (19.6%), Nevada (12.5%), and New Jersey (22.4%). Among injection drug users, testing declined in Louisiana (15%), Michigan (34.3%), and New Jersey (0.6%) and increased in Nebraska (1.7%), Nevada (18.9%), and Tennessee (16.6%). CONCLUSIONS: Confidential HIV reporting by name did not appear to affect use of HIV testing in publicly funded counseling and testing programs.

'Firm' versus 'soft' double pigtail ureteric stents: a randomised blind comparative trial.

It is generally considered that 'firm' double pigtail ureteric catheters, while easier to insert and less prone to migration, may cause more patient discomfort than the 'softer' variety of stent. Objective support for these perceptions is however lacking. The aim of this study was to compare firm and soft stents regarding their ease of insertion, positional stability, biocompatibility and patient tolerance. 155 patients were randomised to receive 'firm' (polyurethane, n = 78) or 'soft' (Sof-Flex, n = 77) stents. Ease and mode of insertion was recorded at time of initial placement. Positional stability, degree of bladder inflammation, stent encrustation and patient tolerance were recorded at the time of removal. Patient tolerance was assessed by symptom score in double-blind fashion. Results showed no significant difference in ease of insertion, positional stability, degree of bladder inflammation or stent encrustation between the two groups. There was a significantly higher incidence of dysuria, renal and suprapubic pain in the firm stent group. There was no significant difference in the incidence of urgency, frequency, nocturia or haematuria. Normal activity and return to work were reported in 67 and 45% of patients with soft and firm stents, respectively. The data indicates that patient tolerance appears to be related to the softness of the stent material.

Prevalence of hepatitis B, hepatitis C, and human immunodeficiency virus infection among women attending prenatal clinics in San Juan, Puerto Rico, from 1989-1990.

OBJECTIVE: To evaluate the prevalence of hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV) among pregnant women in Puerto Rico. METHODS: An anonymous serosurvey was conducted in four prenatal clinics in San Juan, Puerto Rico, involving women presenting consecutively for their first prenatal visit. RESULTS: Nineteen of 997 pregnant women (1.9%, 95% confidence interval [CI] 1.2-3.0) tested positive for HCV antibody (anti-HCV), and eight (0.8%, 95% CI 0.4-1.6) were HIV seropositive. Of the 992 women for whom serum samples were tested for HBV markers, 91 (9.2%, 95% CI 7.5-11.2) had evidence of past or current HBV infection, and four (0.4%, 95% CI 0.1-1.1) were HBV carriers. The age-specific HBV prevalence ranged from 4.1% among women 15-19 years old to 18.5% among those at least 30 years old (P < .001, chi 2 test for trend). Anti-HCV prevalence was also higher among women at least 30 years old compared to younger women (3.1 versus 1.9%; prevalence ratio 1.6, 95% CI 0.6-4.9), although the difference was not statistically significant. Anti-HCV prevalence was higher among women with past or current HBV infection than among women who were not infected (7.7 versus 1.3%; prevalence ratio 5.8, 95% CI 2.3-14.3). CONCLUSIONS: The prevalence of chronic HBV and HCV infection among pregnant women tested in San Juan, Puerto Rico, is comparable to that among pregnant women in the United States. The prevalence of HIV infection among pregnant women in San Juan is higher than among childbearing women in the United States.

Sentinel surveillance of human immunodeficiency virus infection in women seeking reproductive health services in the United States, 1988-1989. The Field Services Branch.

Cases of AIDS among women of reproductive age have increased dramatically since 1981; nearly a third of all cases among females were reported in 1990 alone. Surveillance of human immunodeficiency virus (HIV) infection among women is essential for monitoring the spread of HIV over time and identifying specific populations and geographic areas in need of HIV counseling, testing, and prevention services. Blinded (unlinked) serologic surveys were conducted in the United States and Puerto Rico in sentinel clinics providing reproductive health services to women, including family planning, prenatal care, and abortion services. Seventy-eight of 94 clinics (83%) in 30 cities conducting surveys during 1988 and 1989 detected at least one HIV-positive woman. Clinic-specific prevalence ranged from 0-2.28% (median 0.22%), with rates over 1% occurring in clinics predominantly on the East Coast and in Puerto Rico. Seroprevalence varied by primary type of service, race-ethnicity, and age group. Median rates were higher in clinics offering prenatal services and lower in abortion and family planning clinics in the same cities. In general, women 25-29 years of age showed the highest median rate of infection (0.32%), and rates were higher among black women (median 0.34%) than among Hispanic (median 0.11%) and white women (median 0%). Our data indicate the need to educate women about recognizing and reducing their risk of HIV infection. Reproductive health clinics with high seroprevalence should implement voluntary HIV counseling and testing with appropriate follow-up clinical evaluation and referral for infected women. Clinics with low prevalence should seize the opportunity to enhance HIV education and prevention efforts.

Youth at risk. Sex, drugs, and human immunodeficiency virus.

Adolescents and young adults are at risk for human immunodeficiency virus type 1 infection due to unprotected sexual intercourse and drug use. In 1988 and 1989, blinded surveys were conducted in 84 sexually transmitted disease clinics, 115 women's health clinics, and 19 drug treatment centers in 38 metropolitan areas. Blood specimens from 153,242 clients, aged 15 to 24 years, were tested for human immunodeficiency virus type 1 antibodies after all client identifiers were removed. In sexually transmitted disease clinics, the median rate was 0.4% among 15- to 19-year-olds, compared with 1.4% among 20- to 24-year-olds. Among heterosexual adolescents, rates in females were significantly higher than in males (Wilcoxon signed rank test). Rates in heterosexuals were highest in the northeastern and southeastern United States and in Puerto Rico. In 20- to 24-year-old male clients in sexually transmitted disease clinics who had sex with males, rates ranged from 9.7% to 55.6%. In drug treatment centers, the median rate among 20- to 24-year-old men and women was 8.3% (range, 0% to 33.3%). Rates in women's health clinics were much lower (median, 0.1%). The high rates of infection in certain groups of adolescents and young adults indicate the need for improved care, education, and outreach targeted toward those at high risk.