OBJECTIVE:While nuclear myocardial perfusion imaging (MPI) offers many benefits to patients with known or suspected cardiovascular disease, concerns exist regarding radiation-associated health effects. Little is known regarding MPI practice in Africa. We sought to characterise radiation doses and the use of MPI best practices that could minimise radiation in African nuclear cardiology laboratories, and compare these to practice worldwide.METHODS:Demographics and clinical characteristics were collected for a consecutive sample of 348 patients from 12 laboratories in six African countries over a one-week period from March to April 2013. Radiation effective dose (ED) was estimated for each patient. A quality index (QI) enumerating adherence to eight best practices, identified a priori by an IAEA expert panel, was calculated for each laboratory. We compared these metrics with those from 7 563 patients from 296 laboratories outside Africa.RESULTS:Median (interquartile range) patient ED in Africa was similar to that of the rest of the world [9.1 (5.1-15.6) vs 10.3 mSv (6.8-12.6), p = 0.14], although a larger proportion of African patients received a low ED, ≤ 9 mSv targeted in societal recommendations (49.7 vs 38.2%, p < 0.001). Bestpractice adherence was higher among African laboratories (QI score: 6.3 ± 1.2 vs 5.4 ± 1.3, p = 0.013). However, median ED varied significantly among African laboratories (range: 2.0-16.3 mSv; p < 0.0001) and QI range was 4-8.CONCLUSION:Patient radiation dose from MPI in Africa was similar to that in the rest of the world, and adherence to best practices was relatively high in African laboratories. Nevertheless there remain opportunities to further reduce radiation exposure to African patients from MPI.

Mathew Mercuri, PhD; Thomas N. B. Pascual, MD; John J. Mahmarian, MD; Leslee J. Shaw, PhD; Maurizio Dondi, MD; Diana Paez, MD; Andrew J. Einstein, MD, PhD; for the INCAPS Investigators Group

This study estimates current rates of stress-only imaging in cardiology patients in the United States and worldwide, as well as the potential effect of changes in this rate on the radiation burden to the US population.

Purpose: The study aim was to assess factors that impact on the outcome of radioiodine therapy in patients diagnosed with differentiated thyroid carcinoma (DTC).Materials and Methods: We performed a retrospective cohort study on 256 patients with DTC who underwent thyroidectomy and received radioiodine therapy during December 2003 to January 2012.All patients were followed up for at least 1 year.They were considered diseasefree by the criteria of the revised American Thyroid Association Management Guideline for Patients with Thyroid nodules and DTC (ATA guideline 2009).Results: On Cox univariate analysis, factors associated with disease-free status were age<45, stage I tumor, low risk group by histopathology, unifocal tumor involvement, stimulated serum Tg level at 1st dose of radioiodine therapy and no distant metastasis from 1st post-treatment WBS (post RxWBS).On multivariate analysis, stage I tumor and stimulated serum Tg level at 1st dose of radioiodine therapy < 30 ng/mL were the significant prognostic factors that increased disease-free rate by 1.73 times and 2.60 times, respectively (P-value <0.05).Conclusions: Factors affecting the outcome of radioiodine therapy in our study were age, stage, risk of recurrence by histopathology, unifocal tumor involvement and 1st postRxWBS findings.From these factors, stage I tumor and stimulated serum Tg level at 1st dose of radioiodine therapy were independent prognostic factors that substantial increase the disease-free rate.

Aims To characterize patient radiation doses from nuclear myocardial perfusion imaging (MPI) and the use of radiation-optimizing ‘best practices’ worldwide, and to evaluate the relationship between laboratory use of best practices and patient radiation dose. Methods and results We conducted an observational cross-sectional study of protocols used for all 7911 MPI studies performed in 308 nuclear cardiology laboratories in 65 countries for a single week in March–April 2013. Eight ‘best practices’ relating to radiation exposure were identified a priori by an expert committee, and a radiation-related quality index (QI) devised indicating the number of best practices used by a laboratory. Patient radiation effective dose (ED) ranged between 0.8 and 35.6 mSv (median 10.0 mSv). Average laboratory ED ranged from 2.2 to 24.4 mSv (median 10.4 mSv); only 91 (30%) laboratories achieved the median ED ≤ 9 mSv recommended by guidelines. Laboratory QIs ranged from 2 to 8 (median 5). Both ED and QI differed significantly between laboratories, countries, and world regions. The lowest median ED (8.0 mSv), in Europe, coincided with high best-practice adherence (mean laboratory QI 6.2). The highest doses (median 12.1 mSv) and low QI (4.9) occurred in Latin America. In hierarchical regression modelling, patients undergoing MPI at laboratories following more ‘best practices’ had lower EDs. Conclusion Marked worldwide variation exists in radiation safety practices pertaining to MPI, with targeted EDs currently achieved in a minority of laboratories. The significant relationship between best-practice implementation and lower doses indicates numerous opportunities to reduce radiation exposure from MPI globally.