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Biomedical subjects

A Karellas

Publications and source records attributed to A Karellas.

At least 19 recordsLinked to original sources
PubMed1996

The tailored low dose fluoroscopic voiding cystogram for familial reflux screening.

PURPOSE: Radionuclide voiding cystography is generally advocated as a screening study to detect familial reflux. We assessed the efficacy of tailored low dose fluoroscopic voiding cystography for this purpose. MATERIALS AND METHODS: We evaluated 10 boys and 10 girls 9 months to 10 years old (mean age 5 years) who were siblings of patients known to have reflux. The technique used a low dose fluoroscopic system. A tailored voiding cystographic protocol was designed to minimize gonadal radiation dose. RESULTS: Absence of reflux was confirmed in 10 patients. Mean fluoroscopy time was 19 seconds (range 14 to 22), resulting in mean gonadal radiation exposure of less than 1.5 mrad., which is comparable to the lowest reported doses with the radionuclide technique. After reflux was demonstrated in 10 patients the study was immediately converted to a standard fluoroscopic imaging technique to define lower tract anatomy and quantitate reflux, avoiding a second study. CONCLUSIONS: Tailored low dose fluoroscopic voiding cystography appears to be a practical approach for the assessment of familial reflux.

Child↗
PubMed1994

Maternal umbilicus: ultrasound window to the gravid uterus.

Transabdominal sonograms of 68 consecutive pregnant women were reviewed retrospectively. Images of fetal parts obtained through the umbilical window (UW) were compared with those obtained through the paraumbilical window (PUW) as to (1) thickness of tissue to amniotic cavity, (2) clarity of the part imaged, and (3) noise produced. The paraumbilical tissue thickness had a mean of 18 mm; the umbilical tissue thickness, a mean of 11 mm. In patients where the difference in thickness of their paraumbilical tissue and umbilical tissue was only 0 mm to 6 mm (group 1), the UW improved clarity in 10 of 34 (29%), reduced clarity in 3 of 34 (9%), and did not change clarity in 21 of 34 (62%). Improvement of images with use of the UW was not statistically significant. However, in the group of patients with the difference in tissue thickness between the paraumbilical and umbilical areas of > 6 mm (group 2), clarity was improved in 19 of 32 (60%), reduced in 2 of 32 (6%), and was unaltered in 11 of 32 (34%). In this group the image improvement with the UW was statistically significant. Images through the UW had relatively less noise. In group 1, noise was reduced in 12 of 35 (34%). The effect of the UW on noise reduction was more significant in group 2 (tissue thickness difference > 6 mm): 24 of 31 (77%) of cases.

Female↗
PubMed1994

Methods to calculate the lens efficiency in optically coupled CCD x-ray imaging systems.

In lens-coupled CCD x-ray imaging, the lens efficiency is of critical importance for attaining an x-ray quantum-noise-limited system. However, the equations and the associated parameters of this process have not always been used properly in some of the literature. This can result in the incorrect estimation of the signal-to-noise ratio (SNR). In practice, it is found more convenient to use lens-coupling efficiency equations which assume that the scintillating screen is an extended Lambertian source, since the number of light photons emerging from various scintillating screens has been measured and reported by several investigators. This communication examines several of the most common types of lens-coupling efficiency equations and explains how to use them correctly with other parameters to calculate the SNR of a lens-coupled CCD x-ray imaging system.

Biophysical Phenomena↗
PubMed1994

Tailored low-dose fluoroscopic voiding cystourethrography for the reevaluation of vesicoureteral reflux in girls.

OBJECTIVE: Radionuclide voiding cystography is generally advocated for the reevaluation of proved vesicoureteral reflux. The purpose of this study was to assess the efficacy of tailored low-dose fluoroscopic voiding cystourethrography for this purpose. SUBJECTS AND METHODS: Forty-five girls (2 years 9 months to 19 years 7 months old; mean, 7.4 years) who had proved reflux were examined with tailored low-dose voiding cystourethrography. The technique used a low-dose fluoroscopic system and a computer-based video frame grabber that produced frame-averaged digital video fluoroscopic hard copies. A tailored voiding cystourethrographic protocol was designed to minimize ovarian radiation dose. Digital images were compared with standard 105-mm spot films in a similar group of 25 children. RESULTS: The tailored low-dose fluoroscopic technique produced diagnostically adequate images in all patients that were comparable in quality to standard spot films. The ovarian dose was 1.7-5.2 mrad (0.017-0.052 mGy) with a mean of 2.9 mrad (0.029 mGy). This compared favorably with the lowest reported doses with the radionuclide technique. CONCLUSION: Tailored low-dose fluoroscopic voiding cystourethrography is an attractive and practical alternative to the radionuclide technique in girls with proved vesicoureteral reflux.

Child↗
PubMed1991

Ultrasound attenuation of the calcaneus: a sensitive and specific discriminator of osteopenia in postmenopausal women.

Recent studies have evaluated techniques for estimating bone mass without radiation. The present study compares broadband ultrasound attenuation of the calcaneus and bone densities of the femoral neck and the lumbar spine in 17 normal women and 41 women with osteoporosis. Twenty of the osteoporotic women had spine (n = 16) or femoral neck (n = 4) fractures. There was a significant decrease in the broadband ultrasound attenuation (P less than 0.001) in women with osteoporosis compared with normal women. The osteoporotic women also showed a decrease in vertebral (P less than 0.0001) and femoral neck (P less than 0.0001) densities compared with normal women. At 63 dB/MHz, the sensitivity and specificity of broadband ultrasound attenuation for decreased bone mineral density with or without fractures were 76%. All women with fractures had a broadband ultrasound attenuation less than 72 dB/MHz. This corresponded to a specificity of 41%. To determine whether broadband ultrasound attenuation correlated with trabecular bone volume, samples of cadaver calcaneus were analyzed. The histologic determination showed a significant correlation between broadband ultrasound attenuation and trabecular bone volume (r = 0.992, P = 0.008). These results suggest broadband ultrasound attenuation of the calcaneus reflects bone mass and can be used as a safe and sensitive indicator for decreased axial bone density.

Absorptiometry, Photon↗
PubMed1991

A program to improve mammography skills of practicing radiologic technologists.

Periodic screening mammography and clinical breast examination have significantly reduced the breast cancer mortality rate in the United States for women 50 years of age and older. The Breast Cancer Screening Project of the University of Massachusetts, Worcester, developed a pilot mammography continuing-education program for radiologic technologists that included a didactic and a clinical on-site, hands-on training workshop with preinstruction, postinstruction, and six-month follow-up evaluations to improve their mammography skills. Because of a small sample size, a high dropout rate, and limitations in study design, posttest gains cannot be attributed to the program. Most significant is the finding of wide variability in radiologic technologists' mammography skills, which may compromise mammogram quality and the value of such screening.

Breast Neoplasms↗
PubMed1991

Value of dual-energy CT in differentiating focal fatty infiltration of the liver from low-density masses.

Focal (irregular, partial) fatty infiltration of the liver may simulate neoplastic or other hypodense masses on CT. On the basis of previous observations of the phenomenon that differences in X-ray attenuation diminish with increasing energy of X-rays used, we performed a preliminary study to determine if dual-energy CT could be used to discriminate between fatty infiltration and hypodense liver masses. Dual-energy CT at 140 and 80 kVp was performed in 14 patients undergoing liver biopsy and in seven control subjects with presumedly normal liver. Attenuation measurements were taken, and the changes in attenuation between 140 and 80 kVp were calculated. The mean changes in attenuation were 3.5 H for normal liver (n = 7), 2.5 H for hypodense liver masses (n = 6), 13 H for fatty liver (n = 5), 0.3 H for fatty liver combined with hemochromatosis or hemosiderosis (n = 3), and 2 H for the spleen (n = 18). The change in attenuation increased as the fat content in the liver increased. Analysis of variance showed a statistically significant difference (p less than .001) between fatty liver and the other groups. A difference greater than 10 H was unique to fatty infiltration. These results suggest that dual-energy CT may help to differentiate focal fatty infiltration of the liver from low-density neoplastic or other lesions, but only if the iron content of the liver is not increased.

Adult↗
PubMed1991

Feasibility of universal screening mammography. Lessons from a community intervention.

It is estimated that 44,500 American women will die of breast cancer in 1991. The breast cancer screening guidelines of the American Cancer Society and the National Cancer Institute calling for annual mammography for all women older than 50 years have been endorsed by numerous professional groups. Third-party reimbursement for screening mammography is becoming more prevalent, and payment for screening mammography is now a Medicare benefit. Our studies, conducted as part of a National Cancer Institute grant to increase the routine use of screening mammography and clinical breast examination in women 50 to 75 years of age, have uncovered a number of significant barriers to the implementation of screening guidelines among women, primary care physicians, and providers of mammography services. These barriers, as well as methods to assure the quality of mammography, need to be addressed before universal screening is feasible.

Aged↗
PubMed1990

Dietary modification with dairy products for preventing vertebral bone loss in premenopausal women: a three-year prospective study.

The effect of dietary calcium on vertebral bone mass in women is controversial. In a randomized study we have investigated the effect of dietary modification in the form of dairy products on vertebral bone mass in 30- to 42-yr-old premenopausal women over a 3-yr period. Twenty women increased their dietary calcium intake by an average of 610 mg/day (P less than 0.03) for 3 yr, while 17 age- and weight-matched women served as controls. Calcium intake was monitored by 3-day diet histories and 24-h urinary calcium excretion. The consumption of the dairy products did not alter serum calcium or PTH levels or the fasting urinary calcium to creatinine ratio. Twenty-four-hour urinary calcium excretion increased by 28% (P less than 0.03) in the supplemented women. Dairy product intake was accompanied by increased dietary fat intake, but there were no statistically significant changes in serum cholesterol, low density lipoprotein cholesterol, or high density lipoprotein cholesterol levels. The vertebral bone density in the women consuming increased calcium did not change over the 3-yr period (-0.4 +/- 0.9%). In contrast, the vertebral bone density in the control women declined (-2.9 +/- 0.8%; P less than 0.001) and was significantly lower than that in the supplemented group at 30 and 36 months. The study suggests that dietary modification in the form of dairy products retards vertebral bone loss in premenopausal women. Therefore, increased calcium intake in estrogen-replete premenopausal women may prevent age-related bone loss.

Adult↗
PubMed1989

Radiologic contributions to the investigation and prosecution of cases of fatal infant abuse.

In 1984 we started a two-year program in Worcester (Mass.) and Boston to provide additional radiologic data for the medical investigation of suspected fatal infant abuse. During that period the investigation of 12 cases of unexplained infant death included the review of complete radiographic skeletal surveys by a pediatric radiologist. Autopsies were supplemented with resection, high-detail radiography, and histologic study of all non-cranial sites of suspected osseous injury. Thirty-four bony injuries were noted, including 12 acute and 16 healing fractures of the long-bone metaphyses and posterior-rib arcs in patterns indicative of infant abuse. The investigations determined that there were eight cases of abuse, two accidental deaths, and two natural deaths (sudden infant death syndrome). At this writing, the radiologic and osseous histologic studies appear to have influenced the determination of the manner of death in six of the eight cases of abuse and the criminal prosecution in four of the five convictions. These findings suggest that a thorough postmortem radiologic evaluation followed by selected histologic studies can have an impact on the investigation and prosecution of cases of fatal infant abuse.

Autopsy↗
PubMed1988

Ultrasound attenuation of the os calcis in women with osteoporosis and hip fractures.

Bone ultrasound attenuation of the calcaneus, and vertebral and femoral bone density measured by dual photon absorption were determined in 22 women with osteoporosis, 10 women with hip fractures, and 29 normal, age-matched controls to determine the utility of the ultrasound technique as an indicator of axial osteopenia. Vertebral and femoral neck density and bone ultrasound attenuation were significantly decreased (P less than 0.01) in the women with osteoporosis and those with hip fractures. The sensitivity and specificity of bone ultrasound attenuation was 80% at a value of 50 dB/MHz. At 90% specificity the sensitivity of bone ultrasound attenuation was 65%. The results of this pilot study suggest that ultrasound attenuation, a safe, simple, and radiation-free procedure, may be utilized as an indicator of decreased axial bone mass.

Aged↗
PubMed1988

CT of the pancreas with a fat-density oral contrast regimen.

Visualization of the head of the pancreas by CT was prospectively evaluated in two groups of 100 patients who did not have pancreatic disease. Patients were given either a fat-density oral contrast material (12.5% corn-oil emulsion and metoclopramide) or a conventional high-density oral contrast material (barium suspension or iodinated solution). There was no statistically significant difference in the subjects' tolerance to the two regimens. There was, however, a significant improvement in ability to distinguish the head of the pancreas from the duodenal C-loop when the fat-density contrast material was given. When pancreaticoduodenal discrimination was graded, patients given corn-oil emulsion and metoclopramide received an average score of 0.94, whereas those given the high-density agent received an average score of 0.74, with 1.00 being the highest possible score (p less than .005). These data suggest that for routine CT evaluation of the head of the pancreas, a combination of corn-oil emulsion and metoclopramide may be superior to the conventional high-density oral contrast agents given without metoclopramide.

Administration, Oral↗