Evaluation of light sources and light guides for use in transurethral surgery

An evaluation of the quality of light sources and guides was carried out in response to a demand that sufficient light intensity should always be available for transurethral procedures when bleeding occurs. A light monitor was developed for the rapid assessment of the source intensity and light guide transmission. A simple test protocol was also developed for routine assessment of the sources and guides and for evaluation of new sources and guides before purchase. The sources and guides were classified in order of merit and coded to permit the selection of those of the highest quality; this guarantees a satisfactory level of illumination during surgery.     

Noninvasive detection of ventricular wall motion by electromagnetic coupling

Radiofrequency coils are used as sensors in various applications such as nuclear magnetic resonance (NMR) imaging and displacement cardiograms (DCGs). In most cases the impedance and the resonant frequency of the coil are monitored to provide the required information. The paper describes the changes in reflected impedance and in resonant frequency of a coil when it is placed near a medium with properties ranging from a lossy dielectric to a pure conductor. The theory of interaction between the coil and the medium is investigated and a model based on the use of vector potentials is developed. One prediction of the theory is that placing the coil over body equivalent saline (lossy dielectric) at 15 MHz results in an increase in the inductance of the coil and a resultant decrease in resonant frequency. This prediction was supported experimentally.     

Absence of an association between HLA-DRB1*04 and rheumatoid arthritis in newly diagnosed cases from the community.

OBJECTIVES--To determine HLA-DR4 and DR1 allele frequencies in a series of patients with newly diagnosed early inflammatory arthritis. METHODS--HLA-DR1 and DR4 frequencies were determined by oligonucleotide typing of 208 patients classified as having either rheumatoid arthritis (RA) or undifferentiated inflammatory polyarthritis. RESULTS--The frequency of occurrence of DR4 in these patients with RA did not differ significantly from that in controls in the United Kingdom (42 v 37%). HLA-DR1 was increased in the group with inflammatory polyarthritis (25 v 18%). CONCLUSIONS--The frequency of DR4 is not increased in newly diagnosed community based patients with RA. This supports the hypothesis that DR4 is less important as a marker for susceptibility to RA than it is for disease persistence or severity.     

Short-Ti inversion-recovery pulse sequence: analysis and initial experience in cancer imaging

Inversion recovery (IR), commonly considered a pulse sequence capable of producing T1-weighted images with excellent display of normal anatomy, is versatile: The null point and peak time provide a useful, succinct summary of the properties of IR and its capacity for producing both T1- and T2-weighted images. Shortening of the inversion time (TI) and creation of a short-TI inversion-recovery (STIR) pulse sequence increases sensitivity to malignancy and other abnormalities by making the effects of prolonged T1 and T2 on signal intensity additive and by nulling the signal from fat. The authors examined over 300 patients with various malignancies and compared STIR images with T1- and T2-weighted images obtained at 0.5 T. In 43 cases, signal-difference-to-noise ratios (SD/Ns) were calculated between tumor, fat, and muscle. In general, STIR images demonstrated tumor as a conspicuously high-intensity area in a background of muted, discernible anatomic detail. The good contrast achieved with STIR sequences between tumor and fat (SD/N = 18.1) and tumor and muscle (SD/N = 12.9) consolidated into a single image the information contained separately on T1- and T2-weighted images, which facilitates efficient detection and localization of malignancy.     

Solitary rectal ulcer syndrome: findings at barium enema study and defecography

Sixteen cases of histopathologically proved solitary rectal ulcer syndrome were encountered. Fifteen patients underwent barium enema study; in nine cases the findings--including rectal stricture, granularity of the mucosa, and thickened rectal folds-were nonspecific. In six cases the study was normal. All patients had a long history of defecation disorders, and defecography was performed in all. In seven cases, intussusception of the rectal wall was seen; in another case the intussusception was accompanied by a rectocele. One case showed rectal prolapse. In four cases, failed relaxation of the puborectalis occurred and prevented the passage of the bolus; in another case there was abnormal perineal descent. In two patients studies were normal. In patients with defecation disorders, the possibility of this syndrome should be considered. Defecography is the method of choice for establishing the diagnosis.