Radiation dose and cancer risk in retrospectively and prospectively ECG-gated coronary angiography using 64-slice multidetector CT.

This study aimed to estimate the radiation dose and cancer risk to adults in England, the USA and Hong Kong associated with retrospectively and prospectively electrocardiogram (ECG)-gated coronary computed tomography angiography (CTA) using currently practised protocols in Hong Kong. The doses were simulated using the ImPACT spreadsheet. For retrospectively ECG-gated CTA with pitches of 0.2, 0.22 and 0.24, the effective doses were 27.7, 23.6 and 20.7 mSv, respectively, for males and 23.6, 20.0 and 18.8 mSv, respectively, for females. For prospectively ECG-gated CTA, the effective dose was 3.7 mSv for both males and females. A table of lifetime attributable risks (LAR) of cancer incidence was set up for the English population for the purpose of estimating cancer risk induced by low-dose radiation exposure, as previously reported for US and Hong Kong populations. From the tables, the LAR of cancer incidence for a representative 50-year-old subject was calculated for retrospectively ECG-gated CTA to be 0.112% and 0.227% for English males and females, respectively, 0.103% and 0.228% for US males and females, respectively, and was comparatively higher at 0.137% and 0.370% for Hong Kong males and females, respectively; for prospectively ECG-gated CTA, the corresponding values were calculated to be 0.014% and 0.035% for English males and females, respectively, and 0.013% and 0.036% for US males and females, respectively, and again were higher at 0.017% and 0.060% for Hong Kong males and females, respectively. Our study shows that prospectively ECG-gated CTA reduces radiation dose and cancer risks by up to 87% compared with retrospectively ECG-gated CTA.

Efficacy and complications in peripherally inserted central catheter insertion: a study using 4-Fr non-valved catheters and a single infusate.

The purpose of this prospective study was to evaluate the efficacy and complications associated with the use of 4-Fr single-lumen non-valved peripherally inserted central venous catheters (PICC) for the infusion of long-term antibiotics. Forty-four non-valved PICC were inserted using micropuncture technique by interventional radiologists. Six patients were lost to unrelated death or follow up. The remaining 38 patients (24 men and 14 women; mean age 54.79 years) were analysed. Catheters were placed under ultrasound guidance using micropuncture technique and subsequently advanced over guidewire through peel-away sheath under fluoroscopic guidance. Doppler ultrasound was used before PICC removal in order to detect possible complications. All non-valved PICC were flushed with 5 ml of heparinized saline before and after each antibiotic infusion. Efficacy was evaluated and analysed on the average duration of catheter patency and whether any complication was present. Procedural success rate was 100% in our patient population. Seven patients had complications necessitating early PICC removal with the average patency duration of 44 days (95% confidence interval 7.79-80.21 days), whereas an average indwelling patency duration of the remaining 31 patients with no complication was 30.58 days (95% confidence interval 25.74-35.43 days). Total complication rate was calculated to be 5.58 incidences per 1000 catheter days. Complication rate associated with the placement and use of 4-Fr non-valved PICC for antibiotic therapy was observed to be low when compared with other studies using valved and non-valved PICC for various infusates.

Age-dependent differences in the susceptibility of rats to deltamethrin.

Separate groups of weanling and adult rats were exposed to both behaviorally active and lethal doses of deltamethrin to examine age-dependent toxicity of a pyrethroid over a wide dose range. The acoustic startle response (ASR) was selected for comparison at low doses since it is a sensitive, quantifiable biological indicator of pyrethroid effects in rats. Acute mortality was included for comparison at the upper limit of the dose-response. Deltamethrin was administered by gavage as a single dose in corn oil for all tests. Effects on the ASR were comparable in 21- and 72-day-old rats, with a 4-mg/kg dose decreasing ASR amplitude by approximately 50% (ED50) at both ages. By comparison LD50 values in 11-, 21- and 72-day old male rats were 5.1, 11, and 81 mg/kg, respectively. Thus, 11- and 21-day-old male rats were 16 and 7 times, respectively, more sensitive than adults to acute lethality. The concentration of deltamethrin was measured in whole-brain tissue from weanling and adult males treated with ED50 and LD50 doses. The brain concentration of deltamethrin at the ED50 dose of 4 mg/kg was higher in weanling rats than adults. This suggests a possible functional difference, with weanling rats being less susceptible than adults to a low dose. By comparison, there was an equivalent concentration of deltamethrin in brain tissue following an LD50 dose of 12 mg/kg in weanling rats and 80 mg/kg in adults. These results support age-related differences in pharmacokinetics as the basis for the markedly greater sensitivity of young rats to a lethal dose of deltamethrin.

Efficacy of low-dose iodine-131 ablation of post-operative thyroid remnants: a study of 69 cases.

Low-dose iodine-131 of mean activity 1117 MBq was used to ablate post-operative thyroid remnants in 69 patients with differentiated thyroid cancer. Successful ablation was defined as uptake of less than 1% at 48 h and absence of visible image on the post-ablation scan. Ablation by one dose was successful in 95% of patients after total or subtotal thyroidectomy, and 56% of patients after partial or hemithyroidectomy. All patients with uptake of 10% or less on the pre-ablation scan had successful ablation. The results are compared with other reports using low-dose radioiodine ablation and the significance of the findings discussed.

Gas-liquid chromatography and infrared spectroscopy of resmethrin in nonaqueous aerosols.

Two rapid and precise methods have been developed for the determination of resmethrin in nonaqueous aerosol formulations. The propellents are evaporated, the residue is dissolved in carbon disulfide, and the resulting solution is analyzed by gas-liquid chromatography or infrared spectroscopy. The accuracies of the methods were confirmed by a collaborative study.