effects of weight and injected dose in the liver’s Signal-to-Noise Ratio in patients submitted to PET/CT scans

The quality of the image of 18F-FDG PET/CT scans in overweight patients is commonly degraded. This study evaluates, retrospectively, the relation between SNR, weight and dose injected in 65 patients, with a range of weights from 35 to 120 kg, with scans performed using the Biograph mCT using a standardized protocol in the Nuclear Medicine Department at Radboud University Medical Centre in Nijmegen, The Netherlands. Five ROI’s were made in the liver, assumed to be an organ of homogenous metabolism, at the same location, in five consecutive slices of the PET/CT scans to obtain the mean uptake (signal) values and its standard deviation (noise). The ratio of both gave us the Signal-to- Noise Ratio in the liver. With the help of a spreadsheet, weight, height, SNR and Body Mass Index were calculated and graphs were designed in order to obtain the relation between these factors. The graphs showed that SNR decreases as the body weight and/or BMI increased and also showed that, even though the dose injected increased, the SNR also decreased. This is due to the fact that heavier patients receive higher dose and, as reported, heavier patients have less SNR. These findings suggest that the quality of the images, measured by SNR, that were acquired in heavier patients are worst than thinner patients, even though higher FDG doses are given. With all this taken in consideration, it was necessary to make a new formula to calculate a new dose to give to patients and having a good and constant SNR in every patient. Through mathematic calculations, it was possible to reach to two new equations (power and exponential), which would lead to a SNR from a scan made with a specific reference weight (86 kg was the considered one) which was independent of body mass. The study implies that with these new formulas, patients heavier than the reference weight will receive higher doses and lighter patients will receive less doses. With the median being 86 kg, the new dose and new SNR was calculated and concluded that the quality of the image remains almost constant as the weight increases and the quantity of the necessary FDG remains almost the same, without increasing the costs for the total amount of FDG used in all these patients.

Bioethical perspectives for ageing: the documents produced by the Ethics Councils

Aging attracted keen interest in research, health, education as well as cross-sectors approaches. We researched what has been produced by the National Bioethics/Ethics Councils in the form of opinions or other documents, relating to aging and elderly people. In the websi-tes of the 28 EU councils and 12 other countries, we identified 4 documents relating to aging and 8 opinions, which we analyse. The Councils have proposed to draw the attention and reflection of public opinion to the elderly condition; all agree that the age has its own traits and that matters revert to a “culture of old age”, respect and promotion of a positive aging. Enhance the diversity of modes of aging and the importance of preparing all, promoting literacy for aging, creating social and legal protective elements (Elderly Statute, Observatory of the Elderly Conditions). From the analysis, a set of principles and bioethical elements: [1] respect for human dignity, regardless of the stage of life; [2] recognition of the person’s situation uniqueness to aging; [3] freedom of one’s own decision, which is materialized in respect for autonomy; [4] recognition of the vulnerabilities of the elderly, [5] ethical commitment and social responsibility in monitoring the elderly, [6] non-discrimination by age and [7] the guidance to the conditions of the integral good and quality of life. Aging is an existential step for which we can prepare, on the assumption that human life in its longevity, interweaves those who are older and those younger, on the crucial issue of human existence.