The Gothenburg H70 Birth cohort study 2014-16: design, methods and study population.

To improve health care for older persons, we need to learn more about ageing, e.g. identify protective factors and early markers for diseases. The Gothenburg H70 Birth Cohort Studies (the H70 studies) are multidisciplinary epidemiological studies examining representative birth cohorts of older populations in Gothenburg, Sweden. So far, six birth cohorts of 70-year-olds have been examined over time, and examinations have been virtually identical between studies. This paper describes the study procedures for the baseline examination of the Birth cohort 1944, conducted in 2014-16. In this study, all men and women born 1944 on specific dates, and registered as residents in Gothenburg, were eligible for participation (n = 1839). A total of 1203 (response rate 72.2%; 559 men and 644 women; mean age 70.5 years) agreed to participate in the study. The study comprised sampling of blood and cerebrospinal fluid, psychiatric, cognitive, and physical health examinations, examinations of genetics and family history, use of medications, social factors, functional ability and disability, physical fitness and activity, body composition, lung function, audiological and ophthalmological examinations, diet, brain imaging, as well as a close informant interview, and qualitative studies. As in previous examinations, data collection serves as a basis for future longitudinal follow-up examinations. The research gained from the H70 studies has clinical relevance in relation to prevention, early diagnosis, clinical course, experience of illness, understanding pathogenesis and prognosis. Results will increase our understanding of ageing and inform service development, which may lead to enhanced quality of care for older persons.

The accuracy of quantitative parameters in (99m) Tc-MAG3 dynamic renography: a national audit based on virtual image data.

Assessment of image analysis methods and computer software used in (99m) Tc-MAG3 dynamic renography is important to ensure reliable study results and ultimately the best possible care for patients. In this work, we present a national multicentre study of the quantification accuracy in (99m) Tc-MAG3 renography, utilizing virtual dynamic scintigraphic data obtained by Monte Carlo-simulated scintillation camera imaging of digital phantoms with time-varying activity distributions. Three digital phantom studies were distributed to the participating departments, and quantitative evaluation was performed with standard clinical software according to local routines. The differential renal function (DRF) and time to maximum renal activity (Tmax ) were reported by 21 of the 28 Swedish departments performing (99m) Tc-MAG3 studies as of 2012. The reported DRF estimates showed a significantly lower precision for the phantom with impaired renal uptake than for the phantom with normal uptake. The Tmax estimates showed a similar trend, but the difference was only significant for the right kidney. There was a significant bias in the measured DRF for all phantoms caused by different positions of the left and right kidney in the anterior-posterior direction. In conclusion, this study shows that virtual scintigraphic studies are applicable for quality assurance and that there is a considerable uncertainty associated with standard quantitative parameters in dynamic (99m) Tc-MAG3 renography, especially for patients with impaired renal function.

Uncertainty propagation for SPECT/CT-based renal dosimetry in (177)Lu peptide receptor radionuclide therapy.

A computer model of a patient-specific clinical (177)Lu-DOTATATE therapy dosimetry system is constructed and used for investigating the variability of renal absorbed dose and biologically effective dose (BED) estimates. As patient models, three anthropomorphic computer phantoms coupled to a pharmacokinetic model of (177)Lu-DOTATATE are used. Aspects included in the dosimetry-process model are the gamma-camera calibration via measurement of the system sensitivity, selection of imaging time points, generation of mass-density maps from CT, SPECT imaging, volume-of-interest delineation, calculation of absorbed-dose rate via a combination of local energy deposition for electrons and Monte Carlo simulations of photons, curve fitting and integration to absorbed dose and BED. By introducing variabilities in these steps the combined uncertainty in the output quantity is determined. The importance of different sources of uncertainty is assessed by observing the decrease in standard deviation when removing a particular source. The obtained absorbed dose and BED standard deviations are approximately 6% and slightly higher if considering the root mean square error. The most important sources of variability are the compensation for partial volume effects via a recovery coefficient and the gamma-camera calibration via the system sensitivity.

Assessment of pulmonary vascular resistance by Doppler echocardiography in patients with pulmonary arterial hypertension.

BACKGROUND: Assessment of pulmonary artery pressures, cardiac output (CO) and pulmonary vascular resistance (PVR) is crucial in the management of patients with pulmonary arterial hypertension (PAH). The aim of the present study was to investigate whether Doppler echocardiography can be used to determine PVR in patients with PAH. METHODS: Forty-two patients were included and Doppler echocardiography was performed simultaneously (n = 22) and non-simultaneously (n = 60) with right heart catheterization. The tricuspid regurgitation velocity was used to estimate pulmonary arterial peak systolic and diastolic (PADP) pressures (Bernoulli equation). At the time of pulmonary valve opening, right ventricular pressure equals PADP. The tricuspid regurgitation velocity at the time of pulmonary valve opening was measured by superimposing the time from the QRS to the onset of pulmonary flow on the tricuspid regurgitation velocity envelope. Pulmonary capillary wedge pressure, right atrial pressure and CO were assessed using standard Doppler echocardiography methods. Right heart catheterization was performed using Swan-Ganz catheters and thermodilution for CO determination. RESULTS: The differences (mean +/- SD) between catheter and simultaneous/non-simultaneous Doppler echocardiography were 0.3 +/- 0.8 (p = 0.10)/-0.3 +/- 1.1 (p = 0.06) liter/min for CO, 2.9 +/- 5.1 (p = 0.02)/-1.2 +/- 7.4 (p = 0.2) mm Hg for the transpulmonary gradient (TPG) and 0.3 +/- 2.1 (p = 0.65)/0.8 +/- 2.4 (p = 0.02) Wood unit for PVR. The correlation coefficients between catheter and simultaneous/non-simultaneous Doppler echocardiography were 0.86/0.75 for CO, 0.92/0.90 for TPG and 0.93/0.92 for PVR. CONCLUSIONS: A comprehensive hemodynamic assessment that includes CO, TPG and PVR can be provided by Doppler echocardiography in patients with severe pulmonary hypertension.