| 1. |
- Ausen, Dag, et al.
(författare)
-
Foresight Biomedical Sensors
- 2007
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The foresight study on biomedical sensors has addressed different approaches with future use of biomedical sensors in the health care sector, like: How will biomedical sensors shape the healthcare systems of the future? How can they impact the quality and cost of healthcare and what are the business opportunities in the Nordic region?
|
|
| 2. |
- Gran, Fredrik, et al.
(författare)
-
Adaptive spectral Doppler estimation
- 2009
-
Ingår i: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control. - 0885-3010. ; 56:4, s. 700-714
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, 2 adaptive spectral estimation techniques are analyzed for spectral Doppler ultrasound. The purpose is to minimize the observation window needed to estimate the spectrogram to provide a better temporal resolution and gain more flexibility when designing the data acquisition sequence. The methods can also provide better quality of the estimated power spectral density (PSD) of the blood signal. Adaptive spectral estimation techniques are known to provide good spectral resolution and contrast even when the observation window is very short. The 2 adaptive techniques are tested and compared with the averaged periodogram (Welch's method). The blood power spectral capon (BPC) method is based on a standard minimum variance technique adapted to account for both averaging over slow-time and depth. The blood amplitude and phase estimation technique (BAPES) is based on finding a set of matched filters (one for each velocity component of interest) and filtering the blood process over slow-time and averaging over depth to find the PSD. The methods are tested using various experiments and simulations. First, controlled flow-rig experiments with steady laminar flow are carried out. Simulations in Field II for pulsating flow resembling the femoral artery are also analyzed. The simulations are followed by in vivo measurement on the common carotid artery. In all simulations and experiments it was concluded that the adaptive methods display superior performance for short observation windows compared with the averaged periodogram. Computational costs and implementation details are also discussed.
|
|
| 3. |
- Gudmundson, Erik, et al.
(författare)
-
Overcoming the Nyquist Limit in Blood Flow Velocity Estimation
- 2012
-
Ingår i: 2012 IEEE International Ultrasonics Symposium (IUS'12), Proceedings of. - 1948-5719. ; , s. 1615-1618
-
Konferensbidrag (refereegranskat)abstract
- Spectral Doppler ultrasound imaging typically consists of a spectrogram, showing the velocity distribution of the blood, and a brightness (B-) mode image allowing the operator to navigate. It is desirable to have both high spectral and velocity resolution, so that details in the blood flow can be traced, as well as a high B-mode frame rate to allow for tracking of movements and to adjust the position of the transducer. The blood flow signal is often sampled 1) using alternating transmissions for blood flow estimation and for B-mode imaging, or, 2) by acquiring a full Doppler spectrum and then parts of the B-mode image. The former has the disadvantage that it halves the sampling rate, making it likely that aliasing will occur when imaging fast moving blood or deeply positioned vessels; the latter that gaps appears in the spectrogram, and that if the frame rate of the B-mode images is slow, it will be difficult to track movements. Adaptive methods have been implemented to circumvent such problems, but even so, to get an acceptable frame rate of the B- mode images, the number of transmissions for Doppler estimation will be limited, restricting the spectral resolution. Alternatively, one may use an irregularly spaced emission pattern, but existing work on the topic is limited and generally suffers from poor resolution and spurious velocity components resulting from the irregular sampling pattern. In this paper, we examine the BIAA algorithm, showing that this approach allows for an accurate velocity estimate even from irregularly sampled measurements. Using an irregular emission pattern, with half the emissions used to form the B-mode image, the remaining emissions are found to yield accurate velocity estimates without reducing the maximally measurable velocity and without the spurious velocity components. Moreover, we show that the approach will allow for the same maximal velocity without aliasing as if all emissions would have been used for the velocity estimation.
|
|
| 4. |
- Methi, Fredrik, et al.
(författare)
-
Third dose mRNA vaccination against SARS-CoV-2 reduces medical complaints seen in primary care : a matched cohort study
- 2023
-
Ingår i: BMC Medicine. - 1741-7015. ; 21:1
-
Tidskriftsartikel (refereegranskat)abstract
- Background: SARS-CoV-2 mRNA vaccination has been associated with both side effects and a reduction in COVID-related complaints due to the decrease in COVID-19 incidence. We aimed to investigate if individuals who received three doses of SARS-CoV-2 mRNA vaccines had a lower incidence of (a) medical complaints and (b) COVID-19-related medical complaints, both as seen in primary care, when compared to individuals who received two doses. Methods: We conducted a daily longitudinal exact one-to-one matching study based on a set of covariates. We obtained a matched sample of 315,650 individuals aged 18–70 years who received the 3rd dose at 20–30 weeks after the 2nd dose and an equally large control group who did not. Outcome variables were diagnostic codes as reported by general practitioners or emergency wards, both alone and in combination with diagnostic codes of confirmed COVID-19. For each outcome, we estimated cumulative incidence functions with hospitalization and death as competing events. Results: We found that the number of medical complaints was lower in individuals aged 18–44 years who received three doses compared to those who received two doses. The differences in estimates per 100,000 vaccinated were as follows: fatigue 458 less (95% confidence interval: 355–539), musculoskeletal pain 171 less (48–292), cough 118 less (65–173), heart palpitations 57 less (22–98), shortness of breath 118 less (81–149), and brain fog 31 less (8–55). We also found a lower number of COVID-19-related medical complaints: per 100,000 individuals aged 18–44 years vaccinated with three doses, there were 102 (76–125) fewer individuals with fatigue, 32 (18–45) fewer with musculoskeletal pain, 30 (14–45) fewer with cough, and 36 (22–48) fewer with shortness of breath. There were no or fewer differences in heart palpitations (8 (1–16)) or brain fog (0 (− 1–8)). We observed similar results, though more uncertain, for individuals aged 45–70 years, both for medical complaints and for medical complaints that were COVID-19 related. Conclusions: Our findings suggest that a 3rd dose of SARS-CoV-2 mRNA vaccine administered 20–30 weeks after the 2nd dose may reduce the incidence of medical complaints. It may also reduce the COVID-19-related burden on primary healthcare services.
|
|
