Anticipation of radiation dose to the conceptus from occupational exposure of pregnant staff during fluoroscopically guided electrophysiological procedures

Conceptus dose from occupational exposure. INTRODUCTION: A female employee working in the electrophysiology suite has the right to know potential radiation hazards to the unborn child before she is pregnant or before she decides to formally declare her pregnancy. Moreover, the employer of a declared pregnant worker must evaluate the work situation and ensure that the conceptus dose is kept below the maximum permissible level during the remaining gestation period. The aim of this study was to develop a method for conceptus dose anticipation and determination of maximum workload allowed for the pregnant employee who participates in fluoroscopically guided electrophysiological procedures. METHODS AND RESULTS: A C-arm fluoroscopy system, an anthropomorphic phantom, and a radiation meter were used to obtain scattered air kerma dose rates separately for each of the three fluoroscopic projections typically used in the electrophysiology suite. Air kerma to conceptus dose conversion factors for all trimesters of gestation were calculated using Monte Carlo simulation. A formula is presented for the anticipation of the conceptus dose from occupational exposure of pregnant staff during fluoroscopically guided electrophysiological procedures. Normalized data are provided for conceptus dose estimation from occupational exposure of pregnant staff working in any electrophysiology laboratory. A methodology for estimation of maximum workload allowed for each month of the remaining gestation period of a worker who declared her pregnancy is proposed, which ensures that the regulatory dose limits are not exceeded. CONCLUSION: Data presented may be used for the implementation of a radiation protection program designed for pregnant staff working in an electrophysiological suite.     

The lowest effective dose of botulinum A toxin in adult patients with upper limb spasticity

Objective: To define the lowest effective dose of botulinum toxin type A (Dysport®) and safety in the treatment of adult patients with upper limb spasticity.

Design: This was a prospective, randomized, double-blind, dose-ranging study. Patients received either a placebo or one of three doses of Dysport® (350, 500, 1000?U) into five muscles of affected arm by anatomical and electromyography guidance. Efficacy was assessed periodically throughout the 6-month study period by the Modified Ashworth Scale (MAS), the Action Research Arm Test (ARA), the Barthel Index (BI) and the Visual Analogue Pain Scale (VAS).

Results: Fifty patients were recruited. The four study groups were comparable at baseline with respect to their demographical characteristics and severity of spasticity. All doses of Dysport® studied showed a significant reduction from baseline of muscle tone and pain compared to placebo. However, the effect of functional disability was best at a dose of 500?U and the peak improvement was at week 8 after injection. A dose of 1000?U Dysport produced such an excess degree of muscle weakening that the number of randomized patients was reduced to five. BI and ARA of all patients were decrease after injection. No other adverse event was considered related to the study medication.

Conclusion: This study suggests that treatment with Dysport® reduces muscle tone in adult patients with upper limb spasticity. The optimal dose for treatment of patients with residual voluntary movement in the upper limb appears to be 500?U.     

Comparison between two-point and four-point methods for quantification of apparent diffusion coefficient of normal liver parenchyma and focal lesions. Value of normalization with spleen

Purpose

To compare two quantification techniques of apparent diffusion coefficient (ADC), both in normal liver parenchyma and focal lesions, and to investigate any potential value of normalization.

Materials and methods

Fifty-six consecutive patients underwent MRI examination of the liver, including a single shot spin-echo echo planar imaging diffusion sequence with four b-values (0, 50, 500 and 1000 s/mm²). ADC maps were reconstructed based on a two-point method (b-values: 500 and 1000 s/mm²) and a four-point method (b-values: 0, 50, 500 and 1000 s/mm²). Comparison of absolute ADC measurements of the liver, benign and malignant focal lesions was performed between the two- and four-point techniques. The same analysis was done on normalized ADC values (absolute ADC values divided by spleen ADC values).

Results

The difference between mean two-point and four-point ADC values of normal liver (absolute: 1.237 × 10⁻³, 1.615 × 10⁻³ mm²/s, normalized: 1.40, 1.52, respectively) was statistically significant (p < 0.0001 and p = 0.0061). Significantly higher absolute ADC values of benign and malignant lesions were recorded with the four-point method (2.860 × 10⁻³ and 1.307 × 10⁻³ mm²/s) over the two-point method (2.243 × 10⁻³, and 1.011 × 10⁻³ mm²/s) (p < 0.0001 in both) while the same differences in normalized values were proven statistically non-significant for benign lesions (p = 0.788) and statistically significant for malignant lesions (p = 0.015). Both differences in absolute and normalized ADC values of benign versus malignant lesions based on two- and four-point methods were found to be significant (p < 0.0001).

Conclusion

ADC quantification of the liver may be performed with a two-point method (b-values of 500 and 1000 s/mm²), while normalization of ADC measurements with the spleen is not further improving lesion characterization.     

Maturation of the Tract After Percutaneous Cholecystostomy with Regard to the Access Route

Purpose: To assess the shortest time for catheter removal with regard to the transhepatic or transperitoneal approach in patients undergoing percutaneous cholecystostomy (PC). Methods: In this prospective study, 40 consecutive high-risk patients with acute cholecystitis (calculous, n= 22; acalculous, n= 18) underwent PC by means of a transhepatic (n= 20) or transperitoneal (n= 20) access route. In 28 patients (70%) computed tomography was used for puncture guidance, while in the remaining 12 (30%) the procedures were performed under ultrasound control. A fistulography was performed on the 14th postprocedural day in all patients and was repeated weekly if the tract was found to be immature. The catheter was removed only if a mature tract without evidence of leakage was delineated. Results: In 36 of 40 patients the procedure was technically successful (90%). Three of the unsuccessful punctures were attempted transperitoneally and one transhepatically. Thirty-five of 36 patients showed rapid improvement within the first 48 hr following the procedure (96%). Three of them died of their severe underlying disease (7.5%) and in another three the catheter was accidentally removed prior to the first fistulography (7.5%). A total of 30 patients could be fully evaluated after the procedure: 15 with a transhepatic, and 15 with a transperitoneal PC. Whereas 14 of 15 patients (93%) with transhepatic gallbladder access developed a mature tract after 14 days and the remaining patient after 3 weeks, only 2 of 15 patients (13%) with a transperitoneal route presented a mature tract after 2 weeks (p < 0.0001; χ² test with Yates' correction). Eleven patients (73%) with transperitoneal access required 3 weeks and two patients (13%) 4 weeks for complete tract formation. Conclusion: A period of 2 weeks suffices for the majority of patients to develop a mature tract when the transhepatic access route is used; when using the trans- peritoneal route at least 3 weeks are required. We suggest that the transhepatic route is preferable since it allows earlier removal of the catheter and reduces the incidence of complications and discomfort for the patients. Received: 0/00/00/Accepted: 0/00/00     

Early life and later determinants of adult disease: a 50 year follow-up study of the Newcastle Thousand Families cohort

The relative contribution of socioeconomic, behavioural and biological factors operating in fetal and infant life, childhood and adulthood to risk for cardiovascular disease, respiratory diseases and non-insulin-dependent diabetes in middle age has become an important research issue. All 1142 babies born in Newcastle upon Tyne in May and June 1947 were recruited into a prospective cohort study of child health (the ‘Thousand Families’ study) and followed in great detail to the age of 15 y, with a brief further follow up at age 22 y. Children from poorer families were at greatest risk of severe respiratory tract infection in infancy. Children from professional and managerial families were on average taller and heavier throughout childhood than those from semi- and unskilled manual social classes. Repeated infections in early childhood greatly increased the risk of developing chronic respiratory disease by age 15 y. This paper outlines a new investigation designed to trace surviving members of this cohort and to chart the relationships between their socioeconomic circumstances, lifestyles, experiences and health from birth through to the present day. Existing data on socioeconomic circumstances and infections in infancy and childhood, infant nutrition, birthweight and physical development to age 22 y will be linked to information gained from a new study. This comprises a postal questionnaire survey of study members' adult health, socioeconomic circumstances and lifestyle, and a hospital based clinical examination including heart and lung function, glucose tolerance, blood lipids and anthropometric measurements at age 49–51 y. Out of a target sample of 979 people for whom sufficient data are available on the first year of life, 866 (88%) have been traced and 649 are still resident in the North of England. Those study members who have been traced are highly representative of the original cohort. The Thousand Families cohort provides a unique opportunity for detailed epidemiological study because of the wealth of data available on infant and childhood socioeconomic and family circumstances, all of which was collected prospectively. In addition, there has been comparatively little loss to follow-up since 1948.     

Uncommon locations of hydatid disease: CT appearances

Hydatid disease (HD), already known by Hippocrates, is prevalent and widespread in most sheep-raising countries in Asia, Australia, South America, Near East, and southern Europe. The disease is most commonly due to Echinococcus granulosus and may occur in any organ or tissue. The location is mostly hepatic (75 %) and pulmonary (15 %), and only 10 % occur in the rest of the body [1]. Imaging modalities such as US, CT, and MR imaging are helpful in diagnosing the disease. The reliability of each method depends on the cyst's location in the body [2–5]. The purpose of this essay is to illustrate the use of CT in depicting some unusual locations of HD besides the liver and lung. Received 4 April 1996; Revision received 26 August 1996; Accepted 8 November 1996     

Cerebral excitatory amino acids and Na+, K+-ATPase activity during resuscitation of severely hypoxic newborn piglets

We tested the hypothesis that early brain recovery in hypoxic newborn piglets is improved by resuscitating with an O₂ supply close to the minimum level required by the newborn piglet brain. Severely hypoxic 2-5-d-old anaesthetized piglets were randomly divided into three resuscitation groups: hypoxaemic (n = 8), 21% O₂ (n = 8), and 100% O₂ groups (n = 8). The hypoxaemic group was mechanically ventilated with 12-18% O₂ adjusted to achieve a cerebral venous O₂ saturation of 17-23% (baseline; 45±1%, mean±SEM). During the 2h resuscitation period, extracellular aspartate and glutamate concentrations in the cerebral striatum were higher during hypoxaemic resuscitation (p = 0.044 and p = 0.055, respectively) than during resuscitation with 21% O₂ or 100% O₂, suggesting an unfavourable accumulation of potent excitotoxins during hypoxaemic resuscitation. The cell membrane Na⁺,K⁺-ATPase activity of cerebral cortical tissue after 2 h resuscitation was similar in the three groups (p = 0.30). In conclusion, hypoxaemic resuscitation did not normalize early cerebral metabolic recovery as efficiently as resuscitation with 21% O2 or 100% O₂. Resuscitation with 21% O₂ was as efficient as resuscitation with 100% O₂ in this newborn piglet hypoxia model.     

Eye-lens bismuth shielding in paediatric head CT: artefact evaluation and reduction

Background  

CT scans of the brain, sinuses and petrous bones performed as the initial imaging test for a variety of indications have the potential to expose the eye-lens, considered among the most radiosensitive human tissues, to a radiation dose. There are several studies in adults discussing the reduction of orbital dose resulting from the use of commercially available bismuth-impregnated latex shields during CT examinations of the head.