Cone-beam CT dose and imaging performance evaluation with a modular, multipurpose phantom.

PURPOSE: A modular phantom for dosimetry and imaging performance evaluation in cone-beam computed tomography (CBCT) is reported, providing a tool for quantitative technical assessment that can be adapted to a broad variety of CBCT imaging configurations and clinical applications. METHODS: The phantom presents a set of modules that can be ordered in various configurations suitable to a particular CBCT system. Modules include slabs containing a uniform medium, low-contrast inserts, line-spread features, and disk features suitable to measurement of image uniformity, noise, noise-power spectrum (NPS), contrast, contrast-to-noise ratio (CNR), Hounsfield (HU) accuracy, linearity, spatial resolution modulation transfer function (MTF), and magnitude of cone-beam artifact. Automated software recognizes the phantom configuration in DICOM images and provides structured reporting of such test measures. In any modular configuration, the phantom permits measurement of air kerma in central and peripheral locations with an air ionization chamber (e.g., Farmer chamber). The utility and adaptability of the phantom were demonstrated across a spectrum of CBCT systems, including scanners for orthopaedic imaging (Carestream OnSight 3D, Rochester NY), breast imaging (Doheny prototype, UC Davis), image-guided surgery (IGS, Medtronic O-arm, Littleton MA), angiography (Siemens Artis Zeego, Forcheim Germany), and image-guided radiation therapy (IGRT, Elekta Synergy XVI, Stockholm Sweden). RESULTS: The phantom provided a consistent platform for quantitative assessment of dose and imaging performance compatible with a broad spectrum of CBCT systems. The purpose of the survey was not to obtain head-to-head performance comparison of systems designed for such distinct clinical applications. Rather, the survey demonstrated the suitability of the phantom to a broad spectrum of systems in a manner that provides characterization pertinent to disparate applications and imaging tasks. For example: the orthopaedic CBCT system (pertinent clinical tasks relating to high-resolution bone imaging) was shown to achieve MTF consistent with imaging of high-contrast trabecular bone structures (i.e., the MTF reduced to 10% at spatial frequency, f 10  = 1.2 mm-1 ); the breast system (even higher-resolution imaging of microcalcifications) exhibited f 10  = 2.2 mm-1 ; the IGS system (tasks including both bone and soft-tissue contrast resolution) provided f 10  = 0.9 mm-1 and soft-tissue CNR  = 1.64; the angiography system (soft-tissue body interventions) demonstrated CNR  = 1.2 in soft tissues approximating liver lesions; and the IGRT system (pertinent tasks emphasizing HU linearity and image uniformity) showed linear response with HU values ( R 2  = 1), with a cupping artifact ( t cup  = 5.8%) due to x-ray scatter. CONCLUSIONS: The phantom provides an adaptable, quantitative basis for CBCT dosimetry and imaging performance evaluation suitable to a broad variety of CBCT systems. The dosimetry and image quality metrics are consistent with up-to-date methods for rigorous, quantitative, physics testing and should be suitable to emerging standards for CBCT quality assurance.

Equal dependence of the high prevalence of health problems on age and family income in rural southern areas.

BACKGROUND: People who have periods of low family income are at risk for increased health problems in the future, even if they present a similar clinical picture before the reduction in family income. The association between low income and health status was studied in residents of an area with relatively low-average family income and with a historically unstable economy. METHODS: We surveyed a stratified, clustered sample of residents of Johnson County, Tennessee, using a structured interview. The responses were analyzed in conjunction with national and regional data (National Health Interview Survey). RESULTS: Residents of the geographic area under study had a markedly higher prevalence of self-reported health problems than either the national average or rural areas in the southeast United States. The higher prevalence was accounted for by the combination of age and family income, which had equal effects on health status, but not by age differences alone. CONCLUSIONS: Family income and economic development are critically important to improving community health. Sensible capitation rates in managed care arrangements can be obtained only if the income distribution of an insured population is considered along with their age, sex, and physical health status.

Singleton term breech deliveries in nulliparous and multiparous women: a 5-year experience at the University of Miami/Jackson Memorial Hospital.

OBJECTIVE: The purpose of this retrospective study was to evaluate the feasibility of planned vaginal delivery, the maternal morbidity and mortality, and the short-term perinatal outcome in selected multiethnic women at term with singleton breech presentations. STUDY DESIGN: Singleton breech deliveries were identified from the delivery database between January 1, 1989, and December 31, 1993. A retrospective chart review identified 310 nulliparous and 711 multiparous women at term (37-42 weeks) for a total of 1021. Parameters studied included the success rate of planned vaginal deliveries and the incidences of maternal morbidity, perinatal morbidity, and mortality as a whole stratified by parity and mode of delivery. The Student t test, chi(2) test, and Fisher exact test were used for statistical analysis. RESULTS: Among 1021 women with singleton fetuses in a breech position at term, 191 were candidates for vaginal delivery, and 135 (70.7%) of these deliveries were successful. By parity, 12.3% of 310 nulliparous women and 21.5% of 711 multiparous women were candidates for vaginal delivery; 50% of the former and 75.8% of the latter underwent vaginal delivery. Maternal morbidity was more commonly associated with multiparity and cesarean delivery. Newborn intensive care admissions were equally distributed by parity, and significantly more were for vaginal than cesarean deliveries (17.4% vs 10.8%, P =.036). Premature rupture of the membranes complicated deliveries in 23.9% of the nulliparous women and only 6.5% of the multiparous women (P =.000). CONCLUSION: In this multiethnic population 70.7% of candidates selected for attempted vaginal breech delivery at term were successful. The remaining 29.3% underwent cesarean delivery for labor disorders or nonreassuring fetal heart rate patterns.

A double-blind randomized trial of two dose regimens of misoprostol for cervical ripening and labor induction.

OBJECTIVES: The objective of this study was to compare the efficacy and safety of two dosing regimens of misoprostol for cervical ripening and labor induction. METHODS: Patients who fulfilled the study criteria were randomized to received misoprostol 25 microg or 50 microg intravaginally every 3 h for a total of eight doses for cervical ripening or until labor was established. Endpoints for successful cervical ripening was achievement of Bishop score of nine or greater, and for labor induction reaching the active phase of labor in the first 24 h. The rates of success, duration of first and second stages of labor, type of delivery, significant side effects, and neonatal outcome were measured and compared between the two study groups. Two hundred and fifty-one patients were randomized in two groups--126 received 50 microg and 125 received 25 microg misoprostol. Demographics of the two study groups were similar. RESULTS: Patients in the 50 microg group had a shorter first stage (848 min vs. 1,122 min, P < 0.007), shorter induction-to-vaginal delivery interval (933 min vs. 1,194 min, P < 0.013), decreased incidence of oxytocin augmentation (53.9% vs. 68%, P < 0.015), and decreased total units of oxytocin (2,763 mU vs. 5,236 mU, P < 0.023), but there was a higher hyperstimulation rate (19% vs. 7.2%, P < 0.005). CONCLUSIONS: Successful induction rate, delivery types, and fetal outcome were similar in both groups. Although the rate of vaginal delivery and neonatal outcome were similar in both groups, the 50 microg regimen had shorter first and second stages of labor, and a higher hyperstimulation rate that was easily manageable, allowing for flexibility in using the higher dose in low-risk pregnancies.

Prenatal care in cocaine-exposed pregnancies.

OBJECTIVE: To examine the effect of prenatal care with and without drug rehabilitation on perinatal outcome in cocaine-using women. METHODS: Cocaine-exposed pregnancies of 905 human immunodeficiency virus (HIV)-negative women were frequency matched (ratio 6:1) and compared with 150 nonusers. Cocaine subgroups consisted of 278 women who received prenatal care and drug rehabilitation ("comprehensive care"), 206 women who received prenatal care only, and 421 who received neither. Maternal and fetal complications, drug screening, and attendance were recorded. Pregnancy rates and HIV seroconversion were determined over the year following delivery. RESULTS: The groups were similar in age, race, education and poverty level. Linear trends of increasing incidence of maternal complications were seen across the four groups. Comparing nonusers with cocaine users, the odds ratios, with 95% confidence intervals were: 28.0 (4.2, 103.2) for both anemia and weight under 100 lb; 2.4 (1.8, 5.0) for urinary tract infections; 15 (4.6, 36.1) for syphilis; and 11.2 (4.0, 35.8) for other sexually transmitted diseases. Perinatal outcome measures were similar for nonusers and "comprehensive care" groups but significantly worse for the other two groups. Four maternal deaths and two myocardial infarctions occurred with no care. Positive toxicology at delivery was 1.5 and 4.3 times more likely for the two groups without drug treatment, than for "comprehensive care." Congenital anomalies and HIV seroconversion increased in cocaine users. Repeat pregnancy was less likely and more often drug free with "comprehensive care." CONCLUSION: "Comprehensive care" of the cocaine-using gravida increases the likelihood of carrying to term, having fewer complications, being drug free at delivery, and having fewer exposed repeat pregnancies.

Comparison of production of Staphylococcus intermedius exotoxin among clinically normal dogs, atopic dogs with recurrent pyoderma, and dogs with a single episode of pyoderma.

OBJECTIVE: To determine whether exotoxin production by Staphylococcus intermedius is an important factor in recurrence of pyoderma in atopic dogs. DESIGN: Prospective clinical study. ANIMALS: 30 client-owned dogs (10 clinically normal dogs, 10 atopic dogs with recurrent pyoderma, and 10 dogs with a single episode of pyoderma). PROCEDURE: Specimens for bacterial culturing were obtained from a pustule or papule of affected dogs or from skin of clinically normal dogs. Staphylococcus intermedius was isolated and processed. Supernatants were analyzed for staphylococcal exotoxins. Types of lesions and severity of pruritus were assessed for each dog. RESULTS: Exotoxins A and C were detected in S intermedius isolated from 1 clinically normal dog. In the atopic group, exotoxin C was isolated from 1 dog, exotoxins A and C were isolated from 1 dog, and exotoxin C and toxic shock syndrome toxin-1 were isolated from 1 dog. Exotoxins were isolated from 2 dogs with a single episode of pyoderma (exotoxin C, 1 dog; exotoxins A and C, 1 dog). Lesion types and severity of pruritus varied greatly among dogs with pyoderma and were not associated with detection of exotoxin or type of exotoxin. CLINICAL IMPLICATIONS: Exotoxins were identified from few isolates of S intermedius, and we did not observe an association between type of lesions or severity of pruritus and detection of exotoxins. Production of exotoxin by S intermedius does not play a role in the recurrent nature of pyoderma in atopic dogs or on type of lesion or severity of pruritus associated with pyoderma.

Fetal tissue typing in anticipation of neonatal heart transplantation.

BACKGROUND: Hypoplastic left heart syndrome is among the most common major congenital cardiac anomalies. Fetuses with this anomaly survive but require either reconstructive surgery or heart transplantation postnatally. CASE: A woman whose fetus was diagnosed with hypoplastic left heart syndrome underwent funipuncture for fetal tissue typing. The fetus then was listed for heart transplantation. Once an ABO-compatible donor heart was procured, the fetus was delivered and immediately underwent transplantation. CONCLUSION: In candidates for neonatal heart transplantation, fetal tissue typing allows the search for an ABO-compatible donor heart to begin earlier. This approach minimizes the morbidity associated with postnatal waiting and allows transplantation to take place while the neonate is less immunocompetent.

Effect of a transient, geographically localised economic recovery on community health and income studied with longitudinal household cohort interview method.

STUDY OBJECTIVE: The main purpose of the study was to determine whether the health or economic status of a cohort of residents in an economically troubled geographical area changed between 1990 and 1993. DESIGN: Longitudinal, single cohort, interview survey method with the key variables of health status and economic status. Quasi-experimental pre-post design with economic rebound as the intervention. SETTING: A relatively low income geographical area in a rural, mountainous region before and after an economic rebound. In 1990, the local economy and health care system collapsed because of the closure of a series of manufacturing plants; outward migration from the area peaked. Between 1990 and 1993, new industries opened, and state and private community assistance programmes intervened, resulting in an economic rebound, migration into the area, and marked growth of the health service sector. PARTICIPANTS: A 2% sample of residents of households, using a combination of random, stratified, and clustered sampling. Residents included in the study had lived within the area throughout the 1990-1993 period of the study. MAIN RESULTS: Stable, non-migrating residents had a statistically significant 7% reduction in health status between 1990 and 1993, as measured by a composite of subjective and objective measures. The non-migrating residents also had a significant decrease in average household income ($14,700 in 1990 and $12,400 in 1993 in constant 1990 dollars) during the strong economic expansion, and therefore did not participate in or receive direct economic benefit from the expansion. There was a rapid population increase during the expansion, attributable to inward migrants who were younger and healthier than existing residents. The decline in health for the non-migrating residents was tentatively attributed to either direct or indirect effects of the decline in family income. CONCLUSIONS: Local economic development accompanied by expanded health care services availability can leave existing area residents poorer and less healthy, and this problem may be masked by an abundance of healthier, wealthier inward migrants.

Comparison of conjunctival autografts, amniotic membrane grafts, and primary closure for pterygium excision.

OBJECTIVE: The purpose of the study is to determine whether amniotic membrane can be used as an alternative to conjunctival autograft after pterygium excision. DESIGN: A prospective study of amniotic membrane grafts (group A) and primary closure (group B) was compared retrospectively with conjunctival autografts (group C) in patients with pterygia. PARTICIPANTS: Group A included 46 eyes with primary pterygia and 8 eyes with recurrent pterygia, group B had 20 eyes with primary pterygia, and group C consisted of 78 eyes with primary and 44 eyes with recurrent pterygia. INTERVENTION: For the above three different surgeries, the amount of tissue removed was estimated from histopathologic analysis, and the result was evaluated by clinical examination. MAIN OUTCOME MEASURES: Recurrence, survival analysis, and final appearance were compared. RESULTS: In group A, the recurrence rate was 10.9%, 37.5%, and 14.8% for primary, recurrent, and all pterygia, respectively (mean follow-up, 11 months). These three rates were significantly higher than 2.6%, 9.1%, and 4.9% noted in group C (mean follow-up, 23 months) (P < 0.001, 0.018, and 0.01, respectively). However, the latter recurrence rate was significantly lower than 45% (mean follow-up, 5.2 months) in group B for primary pterygia (P < 0.001). The onset of recurrence was delayed significantly in group C as compared with that of groups A and B. CONCLUSIONS: The relatively low recurrence rate for primary pterygia allows one to use amniotic membrane transplantation as an alternative first choice, especially for advanced cases with bilateral heads or those who might need glaucoma surgery later.

Patterns of cocaine binging: effect on pregnancy.

OBJECTIVE: The purpose of this study was to determine how cocaine and crack binging affected perinatal complications. STUDY DESIGN: Between Jan. 1 and Dec. 31, 1989, patterns of cocaine-crack binging and perinatal consequences in 905 pregnant women from multiethnic, multiracial, inner-city populations were studied. Binging cycles reflect the chaotic lifestyle of drug abuse and multiple obstetric at-risk cofactors as integral parts of binging and are more accurately defined than amount of drugs consumed. RESULTS: Binging patterns in 905 pregnant women who use cocaine-crack as their primary drug were as follows: group 1, 78 women with "erratic" binging that is variable in intervals, duration, and amounts but who are very aggressive drug seekers; group 2, 67 women who binged daily; group 3, 760 women who binged in cycles at 3-, 5-, 7-, or > 7-day intervals. Binges ranged from 26.4 to 34.4 hours. Complications were proportional to the frequency of binging, (linear association p < 0.0007). The prematurity rate in group 1 was unexpectedly as high as that in group 2 (35.9% vs 34.3%). Acute problems (vaginal bleeding 21.8%, abruptio placentae 14.3%, stillbirths 20.5%) were most significant in group 1, while chronic problems (small-for-gestational-age infants 32.8%, systemic infections 31.3%, anemia 35.6%, and low maternal weight [< 100 pounds] 32.8%) were more significant in groups 2 and 3. Odds ratios show that prematurity, abruptio placentae, and vaginal bleeding were two to three times more likely to occur if test results for cocaine were positive at delivery. However, in group 1 the likelihood of abruptio placentae was unchanged whether toxicologic test results were positive (14.3%) or negative (14.0%), reflecting the role of cofactors in binging. CONCLUSION: Erratic use of cocaine-crack results in perinatal complications that are as severe as those occurring with daily binging but the patterns differ. Cofactors play a significant role in outcomes.

Culture, illness, and the biopsychosocial model.

Family medicine has appropriated the biopsychosocial model as a conceptualization of the systemic interrelationships among the biological, the psychological, and the social in health and illness. For all its strengths, it is questionable whether this model adequately depicts the centrality of culture to the human experience of illness. Culture (as meaning system) is not an optional factor that only sometimes influences health and illness; it is prerequisite for all meaningful human experience, including that of being ill. A more adequate model of the relationship between culture and illness would demonstrate the preeminence of culture in the experience of illness among all people, not just members of "exotic" cultures; would view healers as well as patients as dwellers in culture; would incorporate the role of culture as meaning system in linking body, mind, and world; and would promote the significance of the cultural context as a resource for research and therapy.

Cocaine-related maternal death.

Hemodynamic overload, cardiac ischemia, and arrhythmia are postulated to originate from "sex-cocaine" syndrome resulting in maternal and fetal death. High concentrations of cocaine and metabolites in maternal blood, urine, and nasal secretions confirmed recent ingestion. Changes in the maternal life-style may have contributed to the poor pregnancy outcome.

Classifying basic research designs.

Considerable confusion over terminology for classifying basic types of research design in family medicine stems from the rich variety of substantive topics studied by family medicine researchers, differences in research terminology among the disciplines that family medicine research draws from, and lack of uniform research design terminology within these disciplines themselves. Many research design textbooks themselves fail to specify the dimensions on which research designs are classified or the logic underlying the classification systems proposed. This paper describes a typology based on three dimensions that may be used to characterize the basic design qualities of any study. These dimensions are: 1) the nature of the research objective (exploratory, descriptive, or analytic); 2) the time frame under investigation (retrospective, cross-sectional, or prospective); and 3) whether the investigator intervenes in the events under study (observational or interventional). This three-dimensional typology may be helpful for teaching basic research design concepts, for contemplating research design decisions in planning a study, and as a basis for further consideration of a more detailed, uniform research design classification system.

Perinatal implications of cocaine exposure.

Obstetric outcome was reviewed for 139 women who volunteered information on cocaine abuse during pregnancy past 20 weeks. Information on the duration of use during pregnancy was not accurate enough for documentation. In previous pregnancies, only 44.6% of the infants were live born, with spontaneous or therapeutic abortions in 41.1% and stillbirths accounting for 3.6%. In the current pregnancies, 91 patients (66.1%) were nonwhite, and multiple-drug usage was found in 92%, with intravenous cocaine use in 44.6% and freebasing in 31.7% as the main routes of administration. Syphilis or another infection, no prenatal care and poor weight gain (less than or equal to 19 lb) in pregnancy was present in one-third of the patients, while 38% did not know their gestational age. Precipitate labor was found in 63.9% and meconium-stained amniotic fluid in 20.5%. The mean birth weight of the infants was significantly lower than that of the general hospital population; low birth weight (less than 2,500 g) occurred in 36.2%, small size for gestational age in 32.4%, neurologic problems in 30.9% and syphilis in 15.4% of the infants. Congenital abnormalities, in 17.4%, seemed to be multifactorial. The consistent pattern of poor outcome in both the previous and present pregnancies reflects the life-style peculiar to cocaine abusers. Prospective studies are in progress to identify the true incidence of cocaine usage and to outline the counseling of childbearing women against cocaine use during pregnancy, emphasizing prevention since cures are not available.

Evaluation of surgical staples in cesarean section.

Experience with Lactomer absorbable surgical staples (Auto Suture Poly CS 57 disposable surgical stapler) in 62 cesarean sections was compared with an equal number of operations performed with standard techniques. The technique of application of the stapler evolved with experience. Countertraction to staplers with Allis' clamps prevented uterine V incisions. Operative time was longer for the stapled suture group for primary cesarean sections, but was unchanged for repeat procedures. Excellent hemostasis of the uterine incision was achieved even when varicose sinusoidal veins were present. Significant reductions of hemoglobin deficits from 2.16 to 1.31 gm/dl, postoperative anemia from 29% to 6.4%, and endometritis from 22.5% to 6.4% occurred respectively in nonstapled and stapled groups. A reduced hospital stay, shortened by 2.1 days, saved each patient +F42950. Blood loss estimates by surgeons or anesthetists were often at variance. Surgeons' acceptance of the procedure grew with experience. On the basis of these results, use of absorbable staples offers certain advantages in reducing blood loss, infection, and hospital stay in cesarean deliveries.