David Lockhart

Prospective versus Retrospective ECG Gating for 64-Detector CT of the Coronary Arteries: Comparison of Image Quality and Patient Radiation Dose

PURPOSE To compare image quality and patient radiation dose in a group of patients who underwent 64-detector computed tomography (CT) coronary angiography performed with prospective electrocardiographic (ECG) gating with image quality and radiation dose in a group of patients matched for clinical features who underwent 64-detector CT coronary angiography performed with retrospective ECG gating. MATERIALS AND METHODS Institutional review board approval was obtained for this HIPAA-compliant study, and the informed consent requirement was waived due to the retrospective study design. Two independent reviewers separately scored coronary artery segment image quality and overall image quality for 100 cardiac CT studies (50 in each group). Interobserver variability was calculated. Patient radiation dose for the actual examination z-axis length was recorded, and a normalized dose was calculated for a 12-cm z-axis length of a typical heart. RESULTS The two groups matched well for clinical characteristics and CT parameters. There was good agreement for coronary artery segment image quality scores between the independent reviewers (kappa = 0.72). Of the 1253 coronary artery segments scored, the number of coronary artery segments that could not be evaluated in each group was similar (1.1% [seven of 614] in the prospective group vs 1.5% [10 of 647] in the retrospective group, P = .53). Image quality scores were not significantly different when matched for chest cross-sectional area (P > .05). Mean patient radiation dose was 77% lower for prospective gating (4.2 mSv) than for retrospective gating (18.1 mSv) (P < .01). CONCLUSION Use of 64-detector CT coronary angiography performed with prospective ECG gating has similar subjective image quality scores but 77% lower patient radiation dose when compared with use of retrospective ECG gating.

Overcoming barriers to HIV testing: preferences for new strategies among clients of a needle exchange, a sexually transmitted disease clinic, and sex venues for men who have sex with men:

Objective: To determine strategies to overcome barriers to HIV testing among persons at risk. Methods: We developed a survey that elicited testing motivators, barriers, and preferences for new strategies among 460 participants at a needle exchange, three sex venues for men who have sex with men, and a sexually transmitted disease clinic. Results: Barriers to testing included factors influenced by individual concern (fear and discrimination); by programs, policies, and laws (named reporting and inability to afford treatment); and by counseling and testing strategies (dislike of counseling, anxiety waiting for results, and venipuncture). The largest proportions of participants preferred rapid testing strategies, including clinic‐based testing (27%) and home selftesting (20%); roughly equal proportions preferred oral fluid testing (18%), urine testing (17%), and standard blood testing (17%). One percent preferred home specimen collection. Participants who had never tested before were significantly more likely to prefer home self‐testing compared with other strategies. Blacks were significantly more likely to prefer urine testing. Conclusions: Strategies for improving acceptance of HIV counseling and testing include information about access to anonymous testing and early treatment. Expanding options for rapid testing, urine testing, and home self‐testing; providing alternatives to venipuncture; making pretest counseling optional; and allowing telephone results disclosure may encourage more persons to learn their HIV status.

Infectious correlates of HIV-1 shedding in the female upper and lower genital tracts.

Objectives: To determine the effects of vaginal, cervical, and endometrial infections on shedding of HIV-1 RNA in the female genital tract. Design: Cross-sectional. Methods: Antiretroviral-naive women from Nairobi, Kenya with CD4 cell counts ≥ 350 cells/μl had plasma and endocervical wick samples collected for HIV quantification by real-time RNA reverse transcriptase-polymerase chain reaction. Vaginal and cervical Gram stains and endometrial biopsies were obtained. Vaginal Gram stain was used to diagnose bacterial vaginosis and to quantify Lactobacillus levels. Results: Twenty-six of 50 (52%) women had detectable endocervical HIV-1 RNA with a median endocervical viral load of 1760 copies/ml (range: undetectable to 1 030 000 copies/ml). Women with decreased Lactobacillus had 15.8-fold [95% confidenceinterval (CI), 2.0–123] greater endocervical HIV-1 RNA than women with normal Lactobacillus levels. Women with plasma cell (PC) endometritis [≥ 1 PC/high-power field (hpf)] had a 15.8-fold (95% CI, 2.0–120) higher endocervical HIV RNA level than women without PC endometritis. Both these associations remained after controlling for plasma viral load. Cervicitis (≥ 30 polymorphonuclear leukocytes/hpf), however, was not associated with endocervical HIV-1 RNA shedding (P = 0.81). Conclusions: In HIV-1-infected, antiretroviral-naive women without symptoms of pelvic inflammatory disease infection, abnormal vaginal flora and inflammatory cells in the endometrium affected HIV-1 shedding from the lower genital tract. These data suggest that both the upper and lower genital tracts contribute to female HIV-1 genital shedding.

Changes in CSF and plasma HIV-1 RNA and cognition after starting potent antiretroviral therapy.

The authors assessed CSF and plasma HIV-1 RNA and neuropsychological test performance (composite neuropsychological test Z score [NPZ-4]) in 25 HIV-1–infected subjects 4 and 8 weeks after beginning potent antiretroviral therapy that included a protease inhibitor. In the 14 subjects who entered the study on no antiretroviral treatment, NPZ-4 improvement was associated with decline in CSF HIV-1 RNA at both visits (p = 0.001 and p = 0.02), and those treated with zidovudine or indinavir had greater improvement in NPZ-4 at both visits compared to those treated with other drugs (p = 0.003 and p = 0.01).

Whole-chest 64-MDCT of emergency department patients with nonspecific chest pain: Radiation dose and coronary artery image quality with prospective ECG triggering versus retrospective ECG gating.

OBJECTIVE The purpose of this study was to compare the patient radiation dose and coronary artery image quality of long-z-axis whole-chest 64-MDCT performed with retrospective ECG gating with those of CT performed with prospective ECG triggering in the evaluation of emergency department patients with nonspecific chest pain. SUBJECTS AND METHODS Consecutively registered emergency department patients with nonspecific low-to-moderate-risk chest pain underwent whole-chest CT with retrospective gating (n = 41) or prospective triggering (n = 31). Effective patient radiation doses were estimated and compared by use of unpaired Students t tests. Two reviewers independently scored the quality of images of the coronary arteries, and the scores were compared by use of ordinal logistic regression. RESULTS Age, heart rate, body mass index, and z-axis coverage were not statistically different between the two groups. For retrospective gating, the mean effective radiation dose was 31.8 +/- 5.1 mSv; for prospective triggering, the mean effective radiation dose was 9.2 +/- 2.2 mSv (prospective triggering 71% lower, p < 0.001). Two of 512 segments imaged with retrospective gating were nonevaluable (0.4%), and two of 394 segments imaged with prospective triggering were nonevaluable (0.5%). Prospectively triggered images were 2.2 (95% CI, 1.1-4.5) times as likely as retrospectively gated images to receive a high image quality score for each segment after adjustment for segment differences (p < 0.05). CONCLUSION For long-z-axis whole-chest 64-MDCT of emergency department patients with nonspecific chest pain, use of prospective ECG triggering may result in substantially lower patient radiation doses and better coronary artery image quality than is achieved with retrospective ECG gating.

Lower genitourinary tract sources of seminal HIV

Objective: To investigate genital tract sources of HIV-1, we conducted extensive genitourinary sampling of 23 seropositive men without urethritis who shed HIV in their seminal plasma. Design: Semen was collected, then samples were obtained for HIV RNA in blood plasma, urethral fluid, pre-prostate massage fluid/urine (PMF/U) and post-PMF/U, and expressed prostatic secretions. Systematic transrectal ultrasound-guided prostate biopsies obtained from multiple prostate areas were evaluated for HIV RNA and DNA. Results: Seminal HIV RNA levels correlated with HIV RNA levels in urethral fluid and post-PMF/U and with prostate biopsies HIV DNA, but not with expressed prostatic secretions HIV RNA. However, only the HIV RNA level in post-PMF/U independently predicted that in semen (2.77-fold change in semen for each 10-fold change in post-PMF/U; 95% confidence interval, 1.0-7.7) accounting for one third of the seminal HIV RNA level variation, irrespective of adjustment for antiretroviral therapy. Conclusions: These data indicate that distal genitourinary sources other than the prostate appear to be the major source of seminal HIV in men without clinical urethritis or prostatitis. Because the HIV RNA level in blood plasma is not reliable as an independent clinical predictor of virus levels in seminal plasma, these findings also extend the concept that the male genital tract is a distinct virological compartment from blood.

Sexual networks of pregnant women with and without HIV infection.

Objectives: To determine the relationship of HIV infection in pregnant women to sexual network size and other risk factors. Design: Case–control study of women attending the public maternity hospital in Lima, Peru. Methods: We interviewed 75 HIV-seropositive women, 41 of their most recent male partners, and two control groups totaling 137 uninfected pregnant women and 70 of their most recent male partners. Each womans sexual network size was estimated through second and third-generation partnerships over the past year, 5 years and lifetime. Results: Few HIV-seropositive women reported behavioral risk factors for HIV infection, but 79% of male partners were HIV seropositive. Risk factors in male partners included sex with a female sex worker (FSW) or with another man (MSM). The mean 5-year sexual network sizes through the second generation (8.4 persons for HIV-seropositive women, and 2.5 and 1.9 for women in the two control groups) predicted HIV in the women, independently of her own number of partners. These differences were largely attributable to the number of partners reported by male partners. Using data from concurrent studies of FSW and MSM, estimates of 5-year sexual network sizes through the third-generation, excluding contacts with FSW which were protected by consistent condom use, were 672 persons for HIV-seropositive women, and 160 and 224 for women in the two control groups. Conclusions: HIV infection risk among pregnant women in Lima depends largely on their male partners’ risk behaviors. Even monogamous women had very large sexual networks.

Low-Risk Patients With Chest Pain in the Emergency Department: Negative 64-MDCT Coronary Angiography May Reduce Length of Stay and Hospital Charges

OBJECTIVE The current standard-of-care workup of low-risk patients with chest pain in an emergency department takes 12-36 hours and is expensive. We hypothesized that negative 64-MDCT coronary angiography early in the workup of such patients may enable a shorter length of stay and reduce charges. MATERIALS AND METHODS The standard-of-care evaluation consisted of serial cardiac enzyme tests, ECGs, and stress testing. After informed consent, we added cardiac CT early in the standard-of-care workup of 53 consecutive patients. Fifty patients had negative CT findings and were included in this series. The length of stay and charges were analyzed using actual patient data for all patients in the standard-of-care workup and for two earlier discharge scenarios based on negative cardiac CT results: First, CT plus serial enzyme tests and ECGs during an observation period followed by discharge if all were negative; and second, CT plus one set of enzyme tests and one ECG followed by discharge if all were negative. Comparisons were made using paired Students t tests. RESULTS For standard of care and the two CT-based earlier discharge analyses, the mean lengths of stay were 25.4, 14.3, and 5.0 hours; mean charges were

A prospective study of hearing changes after beginning zidovudine or didanosine in HIV-1 treatment-naïve people

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Monotypic human immunodeficiency virus type 1 genotypes across the uterine cervix and in blood suggest proliferation of cells with provirus

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