How good is the ACR accreditation phantom for assessing image quality in digital mammography?

RATIONALE AND OBJECTIVES: The purpose of this study was to evaluate the American College of Radiology (ACR) accreditation phantom for assessing image quality in digital mammography. MATERIALS AND METHODS: Digital images were obtained of an ACR accreditation phantom at varying mAs (constant kVp) and varying kVp (constant mAs). The average glandular dose for a breast with 50% glandularity was determined for each technique factor. Images were displayed on a 5 mega-pixel monitor, with the window width and level settings individually optimized for viewing the fibers, specks, and masses in the ACR phantom. Digital images of the ACR phantom were presented in a random manner to eight observers, each of whom indicated the number of objects visible in each image. RESULTS: Intraobserver variability was greater than interobserver variability for the detection of fibers and specks, but the reverse was true for the detection of masses. As the mAs increased, the number of fibers visible increased from less than one at 5 mAs to all six being visible at 80 mAs. The corresponding number of visible specks increased from 12 to 24, and the number of visible masses increased from 1.25 to about four. Above 26 kVp, object visibility was constant with increasing x-ray tube voltage. Reducing the x-ray tube voltage to 24 kVp, however, reduced the number of visible fibers from six to five, the number of visible specks from 24 to 21.1, and the number of visible masses from four to 3.1. Observer performance was approximately constant for average glandular doses greater than 1.6 mGy, so that the range of lesion detectability in the ACR phantom occurs at doses lower than those normally encountered in clinical practice. CONCLUSION: The current design of the ACR phantom is unsatisfactory for assessing image quality in digital mammography.     

Safe injection of cultured schwann cells into peripheral nerve allografts

The effects of cultured host Schwann cells on axonal regeneration in peripheral nerve allografts were studied. Fischer rats served as recipient animals and Buffalo rats provided nerve allografts. Animals were randomized into 9 groups. Rats receiving tibial nerve isografts were left untreated (group I), or injected with isogeneic Fischer Schwann cells (group II) or placebo suspension (group III). Allografts obtained from Buffalo rats were left untreated (group IV), or received isogeneic Fischer Schwann cells (group V), 2 mg/kg Cyclosporin A and Fischer Schwann cells (group VI), 5 mg/kg Cyclosporin A (group VII), or 5 mg/kg Cyclosporin A with Schwann cells (group VIII). No Schwann cell tumors were identified 4 or 8 weeks postoperatively. Group IX animals, harvested 3 days postoperatively, demonstrated no evidence of injection injury. Schwann cells modestly improved axonal regeneration in both isografts and allografts and may have a clinical role in the treatment of peripheral nerve allografts.     

Morbidity and the impact on daily activities associated with catheter drainage after acute urinary retention

OBJECTIVE: To evaluate the effect on quality of life of being discharged home with a catheter before definitive treatment in patients with acute urinary retention (AUR). PATIENTS AND METHODS: Patients attending the emergency department with AUR were assessed and discharged home with a catheter if they fulfilled predetermined criteria. They were admitted to the day-care unit for urological assessment and completed a disease-specific quality-of-life questionnaire. RESULTS: Of 101 patients presenting to the emergency department in AUR, 84 were sent home after catheterization (83%); 78 (93%) patients completed the questionnaire. The major side-effects reported were urinary leak (46%), mild haematuria (44%), urgency (42%), pain around the penis (42%), painful erection (31%) and catheter blockage (26%). Only 12% of patients felt having a catheter was very inconvenient and 93% would find it acceptable to have a catheter in future. CONCLUSION: A significant minority of patients discharged home with a catheter had side-effects related to their catheter but were not greatly inconvenienced, and their capacity to carry out normal daily activities was not impaired. The immediate discharge of patients in AUR and planned treatment will enable better use of inpatient urology resources.     

CDC growth charts: United States

OBJECTIVES: This report presents the revised growth charts for the United States. It summarizes the history of the 1977 National Center for Health Statistics (NCHS) growth charts, reasons for the revision, data sources and statistical procedures used, and major features of the revised charts. METHODS: Data from five national health examination surveys collected from 1963 to 1994 and five supplementary data sources were combined to establish an analytic growth chart data set. A variety of statistical procedures were used to produce smoothed percentile curves for infants (from birth to 36 months) and older children (from 2 to 20 years), using a two-stage approach. Initial curve smoothing for selected major percentiles was accomplished with various parametric and nonparametric procedures. In the second stage, a normalization procedure was used to generate z-scores that closely match the smoothed percentile curves. RESULTS: The 14 NCHS growth charts were revised and new body mass index-for-age (BMI-for-age) charts were created for boys and girls (http://www.cdc.gov/growthcharts). The growth percentile curves for infants and children are based primarily on national survey data. Use of national data ensures a smooth transition from the charts for infants to those for older children. These data better represent the racial/ethnic diversity and the size and growth patterns of combined breast- and formula-fed infants in the United States. New features include addition of the 3rd and 97th percentiles for all charts and extension of all charts for children and adolescents to age 20 years. CONCLUSION: Created with improved data and statistical curve smoothing procedures, the United States growth charts represent an enhanced instrument to evaluate the size and growth of infants and children.     

The effect of fuel source on amino acid metabolism in critically ill patients.

The ideal energy substrate for critically ill patients receiving total parenteral nutrition (TPN) remains controversial. While glucose has been proved to have nitrogen sparing properties in postoperative patients, critically ill patients tolerate glucose loads poorly and fat appears to be an obligatory fuel in sepsis. Furthermore, it is not yet certain whether the changes in whole body protein metabolism induced by critical illness are influenced by the nature of the TPN provided. This study was conducted on patients admitted to a surgical intensive care unit (SICU) who fulfilled the criteria of requiring TPN and mechanical ventilation for at least four days. Patients were randomized to receive either glucose (G) or equicaloric proportions of glucose and lipid (GF) as an intravenous energy source. TPN was commenced early, within 24-48 hr of trauma or surgery and admission to the ICU. Nonprotein calorie intake was 125% of calculated basal energy expenditure. Nitrogen balance was calculated from 24-hr urinary urea excretion. Protein synthesis, turnover, and catabolism were measured on Day 4 of the study using an established radiolabeled C14-leucine technique. Degree of sepsis and illness were calculated using published scores. Fifty patients entered the trial but 32 were excluded by Day 4. Of the 18 patients completing an initial four day study, eight went on to complete a second study on the alternative regimen--a total of 26 studies (14 G, 12 GF). Net protein synthesis was achieved in 18 studies (12 G, 6 FG) and positive nitrogen balance by Day 4 in 22 studies. Four patients on the G regimen were withdrawn due to glucose intolerance while none of the patients on GF developed glucose intolerance or hyperlipidaemia. Both whole body protein synthesis and catabolism correlated significantly with degree of sepsis. The type of TPN fuel used, G and GF, did not appear to influence whole body protein dynamics, both regimens achieving greatly improved whole body protein kinetics.     

Correlation of release and actions of cholecystokinin in dogs before and after vagotomy

Pancreatic secretion of enzymes and gallbladder contraction in response to intestinal stimulants are thought to be mediated through the vagus nerve and by means of release of cholecystokinin (CCK). The effect of truncal vagotomy on the release of CCK, pancreatic protein secretion, and gallbladder pressure (all stimulated by intraduodenal instillation of oleate) was studied in five dogs. Each dog was prepared with chronic pancreatic and gastric fistulas and catheter cholecystostomies. Simultaneous measurements were made of plasma CCK (by radioimmunoassay), pancreatic protein secretion, and gallbladder pressure (by perfused catheter technique) before and during intraduodenal administration of oleate. Before truncal vagotomy, intraduodenal oleate caused increases in plasma CCK (from 82 +/- 6 to 208 +/- 32 pg/ml), pancreatic protein secretion (from 83 +/- 8 to 165 +/- 15 mg/15 min), and gallbladder pressure (from 11 +/- 2 to 27 +/- 2 cm H2O) (all measured from basal state to 120 minutes). Truncal vagotomy caused a 45% decrease in the output of pancreatic protein in response to oleate and completely abolished the increase in gallbladder pressure, but it caused no change in release of CCK. The correlations between plasma CCK and pancreatic protein secretion before truncal vagotomy (r = 0.86) and after truncal vagotomy (r = 0.77) were highly significant. The correlation between plasma CCK and gallbladder pressure was highly significant before (r = 0.91) but not after (r = 0.42) truncal vagotomy. This study demonstrates that truncal vagotomy inhibits pancreatic protein secretion and gallbladder pressure in response to fat but does not interfere with release of CCK. The effects may be due to interruption of vagus-mediated reflexes between the intestine and the pancreas and gallbladder. The good correlation between plasma concentrations of CCK and both pancreatic protein secretion and gallbladder pressure provides evidence that the radioimmunoassay measures biologically active CCK.     

Radiology of postnatal skeletal development

Thirty-one pairs of distal humeri were obtained from human cadavers ranging in age from full-term neonates to fourteen years. These were studied morphologically and roentgenographically. Specimen roentgenography using air/cartilage interfacing demonstrated both osseous and cartilaginous components of the epiphyses. These roentgenographic aspects of development are discussed and illustrated to provide a basic reference index.The supracondylar region is characterized by a fossa which initially is in both metaphysis and epiphysis, but migrates to the metaphysis completely within the first year. On either side of the fossa are osseous columns, which contrast with the broad metaphyseal bone above the columns. Within the fossa, anteriorly and posteriorly, are fat pads which may be elevated by intraarticular hematoma or reactive joint fluid. The physeal contour initially is transverse and smooth. Lappet formation progressively demarcates the epicondylar physeal regions, with the medial one becoming a functionally, but not histologically separate region.The capitellum is the first region to develop a secondary ossification center. This progressively expands into the trochlear portion of the epiphysis, a factor which predisposes to lateral condyle fracture propagation across the trochlear articular surface. The trochlea characteristically ossifies by multiple foci which fuse over time, often creating an irregular appearance to the developing ossification center. Epicondylar ossification tends to be from solitary foci. The lateral epicondylar center fuses with the capitellar center, whereas the medial epicondyle tends to be a functionally separate entity throughout development and does not normally fuse to the trochlear ossification center.