Reduced-bandwidth MR imaging of the head at 1.5 T1

A decrease in the magnetic resonance (MR) imaging bandwidth can be used to increase the signal-to-noise ratio (S/N) at constant imaging time or to maintain the S/N for reduction of imaging time. The effect of bandwidth reduction from the default value of 16 kHz to 8 kHz was evaluated prospectively in 50 patients referred for MR imaging of the head. On intermediate (2,000/30 [repetition time msec/echo time msec]) and more T2-weighted (2,000/90) studies, there were no definite missed diagnoses and no diagnostically important changes in lesion characteristics when the reduced-bandwidth technique was used to obtain half- or quarter-time studies, excluding differences attributable to unintentional changes in patient position between image acquisitions. Chemical shift misregistration artifacts associated with reduced bandwidth are easily recognized with experience and do not interfere with diagnosis, as the artifacts occur in characteristic locations and diminish in most anatomic locations with increasing echo time. This study suggests the feasibility of reduced-bandwidth techniques in clinical MR imaging of the head at high field strength to achieve an increased S/N, to decrease imaging time, or to obtain images in additional projections.     

Clinical indicators of mycobacteraemia in adults admitted to hospital in Blantyre

The aims of the study were to measure the prevalence and outcome of mycobacteraemia in febrile hospitalised adults; to determine what proportion could be identified using routine methods; to assess clinical indicators of mycobacteraemia and the usefulness of a diagnostic trial of anti-TB treatment. We prospectively examined adults with fever or a history of fever admitted to adult medical wards of QECH, Blantyre. All had blood cultured for bacteria and mycobacteria, chest x-ray and sputum smears. M. tuberculosis was the commonest blood isolate, affecting 57 of 344 patients (17%). In 44 (77%) patients with mycobacteraemia, TB was identified using routine investigations; in only 6 (11%) it was not suspected. Strong clinical indicators of mycobacteraemia were anaemia, HIV seropositivity, cough, chronic fever, and a clinical diagnosis of AIDS on the day of admission. Of nine patients selected for a therapeutic trial of TB treatment, six had mycobacteraemia, of whom five died during the trial. Mortality on short course chemotherapy on the TB ward after one month, was similar whether patients had mycobacteramia (21%) or not (32%). TB can be identified with routine methods in most patients with mycobacteraemia. If treated, mycobacteraemia has as good an early outcome as TB without mycobacteraemia. Strengthening of basic facilities is likely to improve detection and treatment of mycobacterial disease.     

Renal allografts: prospective analysis of Doppler sonography

Fifty-six consecutively transplanted renal allografts were prospectively evaluated with serial Doppler sonographic examinations. Thirty-eight episodes of transplant rejection in 32 patients (63% proved pathologically) and 24 episodes of acute tubular necrosis (ATN) in 24 patients were encountered. The Doppler spectral waveform was characterized by means of the pulsatility index (PI), systolic/diastolic ratio (SDR), diastolic/systolic ratio (SDR), diastolic/systolic ratio (DSR), and resistive index (RI). Accuracy was optimized with use of top normal values as follows: PI = 1.8, SDR = 4.0, DSR = 0.25, RI = 0.75. There were no significant differences in the indices for those patients undergoing rejection versus those with ATN. The sensitivity for predicting transplant rejection was adversely affected by the history of either ATN or a previous rejection episode in the same allograft. Comparison with concurrent radionuclide examinations revealed similar sensitivities for rejection with scintigraphy and sonography. Differentiation of ATN from rejection was more reliable with scintigraphy than with sonography.     

Laser angioplasty: controlled delivery of argon laser energy

A laser catheter system that integrates balloon and fiberoptic technologies was evaluated. In vitro tissue studies were conducted to compare the tissue response to laser irradiation from a bare optical fiber (undiverged light beam) and from a fiber with an optical assembly (diverged light beam). An in vivo study of occluded and unoccluded canine femoral arteries examined coaxial alignment of the diverged light beam and the resultant thermal effects. In the in vitro studies, a diverged laser light beam effected maximum tissue ablation (mean crater diameter, 1.81 mm +/- 0.44) at a distance of only 3 mm from the optical fiber tip. The in vivo study demonstrated the ability of a specially designed balloon catheter to align the diverged laser beam coaxially within the arterial lumen. This laser catheter system successfully avoids the risks of inadequate tissue removal and perforation.     

Conversion disorders in adolescents: a practical approach to rehabilitation

Young people with conversion disorders require a different treatment approach compared with those who have organic illness. This paper describes a team approach which is based on detailed assessment, explanation of the vicious cycle, accepting the patient's symptoms, working towards achievable goals, encouraging bravery, rewarding 'wellness' behaviour, ignoring abnormal behaviour and supervising re- integration into school.      

Glutamatergic control of the expression of the proenkephalin gene in rat frontoparietal cortical slice cultures

The expression of the proenkephalin (PEnk) gene in rat neocortex develops during the first two postnatal weeks in an outside first- inside last mode that is opposite to the gradient of neurogenesis. To test whether the distribution of PEnk gene expression depends on the formation of the local circuitry, we examined the role of glutamate neurons in the expression of the gene in slice cultures of rat frontoparietal cortex. In situ and Northern blot hybridization were used for analysis. In slices explanted at postnatal day 6, the neuronal expression of the PEnk gene developed as in vivo. The expression responded to glutamate receptor agonists and antagonists in a time- dependent manner. After 2 days in vitro the expression of the gene was only enhanced by N-methyl-D-aspartate receptors, whereas after 7 days in vitro AMPA receptors also regulated the expression. We concluded that glutamate neurons are involved in the development and maintenance of the PEnk gene expression in the neocortex.      

Percutaneous dilation of benign biliary strictures

Percutaneous balloon dilation of benign biliary strictures was successful in 15 of 18 patients in whom the procedure was attempted. Successful dilation was achieved in nine of 11 patients who had biliary enteric strictures, with follow-up of 22-55 months (mean, 35.4 months) after catheter removal in seven patients. Five of six strictures in the biliary tree that developed after surgery were successfully dilated, with long-term follow-up available in two patients (58 and 42 months). A patient with an inflammatory common bile duct stricture that was successfully dilated was followed up for 18 months. Percutaneous dilation of biliary tract strictures is a promising technique with good long-term results and may be the initial treatment of choice in biliary stricture management.