Serial Assessment of Coronary Flow Reserve by Rubidium-82 Positron Emission Tomography Predicts Mortality in Heart Transplant Recipients.

OBJECTIVES: This study aimed to evaluate the long-term prognostic value of serial assessment of coronary flow reserve (CFR) by rubidium Rb 82 (82Rb) positron emission tomography (PET) in heart transplantation (HT) patients. BACKGROUND: Cardiac allograft vasculopathy is a major determinant of late mortality in HT recipients. The long-term prognostic value of serial CFR quantification by PET imaging in HT patients is unknown. METHODS: A total of 89 patients with history of HT (71% men, 7.0 ± 5.7 years post-HT, age 57 ± 11 years) scheduled for dynamic rest and stress (dipyridamole) 82Rb PET between March 1, 2008 and July 31, 2009 (PET-1) were prospectively enrolled in a single-center study. PET myocardial perfusion studies were reprocessed using U.S. Food and Drug Administration-approved software (Corridor 4DM, version 2017) for calculation of CFR. Follow-up PET (PET-2) imaging was performed in 69 patients at 1.9 ± 0.3 years following PET-1. Patients were categorized based on CFR values considering CFR ≤1.5 as low and CFR >1.5 as high CFR. RESULTS: Forty deaths occurred during the median follow-up time of 8.6 years. Low CFR at PET-1 was associated with a 2.77-fold increase in all-cause mortality (95% confidence interval [CI]: 1.34 to 5.74; p = 0.004). CFR decreased over time in patients with follow-up imaging (PET-1: 2.11 ± 0.74 vs. PET-2: 1.81 ± 0.61; p = 0.003). Twenty-five patients were reclassified based on PET-1 and PET-2 (high to low CFR: n = 18, low to high CFR: n = 7). Overall survival was similar in patients reclassified from high to low as patients with low to low CFR, whereas patients reclassified from low to high had similar survival as patients with high to high CFR. In multivariate Cox regression of patients with PET-2, higher baseline CFR (hazard ratio [HR] for a 0.73 unit (one SD) increase: 0.36, 95% CI: 0.16 to 0.82) and reduction in CFR from PET-1 to PET-2 (HR for a 0.79 unit (one SD) decrease: 1.50 to 7.84) were independent predictors of all-cause mortality. CONCLUSIONS: Serial assessment of CFR by 82Rb PET independently predicts long-term mortality in HT patients.

Application of new imaging and calculation techniques to activity and dose assessment in the case of a 106Ru contaminated wound.

The aim of this paper is to describe the dosimetric evaluation of a point contamination that occurred in a laboratory during the examination of an irradiated sample. The incident led to point contamination of the operator's finger due to the presence of mainly 106Ru, with its progeny, 106Rh. The paper reports on the activity and dose assessment, performed using several methods. The measured activity was obtained using a conventional device based on a germanium detector and confirmed using software developed at IRSN, based on reconstruction of voxel phantom associated with the Monte Carlo N-Particle code (MCNP) for in vivo measurement. Two dose assessment calculations were performed using both analytical and Monte Carlo methods, applying the same approach as for activity assessment based on the personal computational phantom of the finger. The results are compared, followed by a discussion on the suitability of the tools described in this study.

A comparison of radiopharmaceutical agents used for the diagnosis of pulmonary embolism.

Radioactive gas or technetium-99m aerosols are used to perform pulmonary ventilation scintigraphy. The aim of this study was to compare three radiopharmaceuticals, Kryptoscan, Technegas and Venticis II, in terms of their costs and user preferences rather than on the basis of diagnostic efficacy. For each radiopharmaceutical agent, an analysis questionnaire was sent to nuclear medicine departments setting out the criteria (and subcriteria) to be assessed: diagnosis quality: imaging quality, distribution homogeneity, examination procedures and capacity to examine particular patients (e.g. smokers); safety: for patient, paramedical and medical staff and the environment; use: availability in cases of emergency, ergonomics of the apparatus, simplicity and time of preparation. A score, ranging from 0 to 5, and a weighting (importance of one criterion with regard to the others) were assigned to each criterion. The direct cost of a ventilation (drugs, generator systems, disposable materials) was calculated for each radiopharmaceutical agent according to the number of patients examined per day (1-6) and the number of examination days per week (2-5). Fourteen questionnaires concerning at least two of the products were returned out of the 30 mailed. A 'preference score' was calculated using Pharma Decision software. The mean score of Kryptoscan was significantly higher than that of Venticis II (444 vs. 286, P < 0.001) and higher than the mean score of Technegas (444 vs. 344, P < 0.01). For Venticis II and Technegas, the changes in patient direct costs were minor and depended on the number of patients per day and the number of examination days per week. Respectively, they were: $US 117.66 (5 patients.day-1; 5 days.week-1) to $US 147.74 (2 patients.day-1; 2 days.week-1) and $US 56.60 (6 patients.day-1; 5 days.week-1) to $US 132.08 (2 patients.day-1; 2 days.week-1). The direct cost of ventilation using Kryptoscan varied only according to the number of patients examined per day: $US 104.66 (6 patients.day-1) to $US 266.47 (2 patients.day-1). This study shows that Kryptoscan appears to be preferable for ventilation scintigraphy whenever at least four patients are examined daily.