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Ambarki K.,Umea Hospital | Ambarki K.,Center for Biomedical Engineering and Physics | Wahlin A.,Umea Hospital | Wahlin A.,Center for Functional Brain Imaging | And 7 more authors.
American Journal of Neuroradiology

BACKGROUND AND PURPOSE: The arterial spin-labeling method for CBF assessment is widely available, but its accuracy is not fully established. We investigated the accuracy of a whole-brain arterial spin-labeling technique for assessing the mean parenchymal CBF and the effect of aging in healthy volunteers. Phase-contrast MR imaging was used as the reference method. MATERIALS AND METHODS: Ninety-two healthy volunteers were included: 49 young (age range, 20-30 years) and 43 elderly (age range, 65-80 years). Arterial spin-labeling parenchymal CBF values were averaged over the whole brain to quantify the mean pCBFASL value. Total CBF was assessed with phase-contrastMRimaging as the sum of flows in the internal carotid and vertebral arteries, and subsequent division by brain volume returned the pCBFPCMRI value. Accuracy was considered as good as that of the reference method if the systematic difference was less than 5 mL/min/100 g of brain tissue and if the 95% confidence intervals were equal to or better than-10 mL/min/100 g. RESULTS: pCBFASL correlated to pCBFPCMRI (r-0.73; P<.001). Significant differences were observed between the pCBFASL and pCBFPCMRI values in the young (P<.001) and the elderly (P<.001) volunteers. The systematic differences (mean-2 standard deviations) were4 14 mL/min/100 g in the young subjects and 6 < 12 mL/min/100 g in the elderly subjects. Young subjects showed higher values than the elderly subjects for pCBFPCMRI (young, 57<8 mL/min/100 g; elderly, 54-7 mL/min/100 g; P<.05) and pCBFASL (young, 61<10 mL/min/100 g; elderly, 48 < 10 mL/min/100 g; P < .001). CONCLUSIONS: The limits of agreement were too wide for the arterial spin-labeling method to be considered satisfactorily accurate, whereas the systematic overestimation in the young subjects and underestimation in the elderly subjects were close to acceptable. The age-related decrease in parenchymal CBF was augmented in arterial spin-labeling compared with phase-contrast MR imaging. Source

Alrifaiy A.,Gothenburg University | Alrifaiy A.,Lulea University of Technology | Alrifaiy A.,Center for Biomedical Engineering and Physics | Borg J.,Lulea University of Technology | And 5 more authors.
BioMedical Engineering Online

The response and the reaction of the brain system to hypoxia is a vital research subject that requires special instrumentation. With this research subject in focus, a new multifunctional lab-on-a-chip (LOC) system with control over the oxygen content for studies on biological cells was developed. The chip was designed to incorporate the patch clamp technique, optical tweezers and absorption spectroscopy. The performance of the LOC was tested by a series of experiments. The oxygen content within the channels of the LOC was monitored by an oxygen sensor and verified by simultaneously studying the oxygenation state of chicken red blood cells (RBCs) with absorption spectra. The chicken RBCs were manipulated optically and steered in three dimensions towards a patch-clamp micropipette in a closed microfluidic channel. The oxygen level within the channels could be changed from a normoxic value of 18% O 2 to an anoxic value of 0.0-0.5% O 2. A time series of 3 experiments were performed, showing that the spectral transfer from the oxygenated to the deoxygenated state occurred after about 227 ± 1 s and a fully developed deoxygenated spectrum was observed after 298 ± 1 s, a mean value of 3 experiments. The tightness of the chamber to oxygen diffusion was verified by stopping the flow into the channel system while continuously recording absorption spectra showing an unchanged deoxygenated state during 5400 ± 2 s. A transfer of the oxygenated absorption spectra was achieved after 426 ± 1 s when exposing the cell to normoxic buffer. This showed the long time viability of the investigated cells. Successful patching and sealing were established on a trapped RBC and the whole-cell access (Ra) and membrane (Rm) resistances were measured to be 5.033 ± 0.412 M Ω and 889.7 ± 1.74 M Ω respectively. © Alrifaiy et al.; licensee BioMed Central Ltd. Source

Lindahl O.A.,Lulea University of Technology | Lindahl O.A.,Center for Biomedical Engineering and Physics | Lindahl O.A.,Umea University | Nyberg M.,Lulea University of Technology | And 5 more authors.
IFMBE Proceedings

Prostate cancer (PCa) is the most common cancer form for men in Europe. A sensor system combining Raman spectroscopy and stiffness sensing with a resonance sensor has recently been developed by us for prostate cancer detection. In this study the sensor system has been used for measurements on two slices of fresh human prostate tissue. The stiffness sensor could detect locations slices with significantly different stiffness contrasts (p < 0.05). Raman spectroscopic measurements could be performed with the dual-modality probe for tissue classification. The findings are important for the continued development of a combination probe for prostate cancer detection. © Springer International Publishing Switzerland 2015. Source

Nyberg M.,Lulea University of Technology | Nyberg M.,Center for Biomedical Engineering and Physics | Nyberg M.,Center for Biomedical Engineering and Physics | Jalkanen V.,Center for Biomedical Engineering and Physics | And 9 more authors.
Journal of Medical Engineering and Technology

Prostate cancer is the most common cancer for men in the western world. For the first time, a dual-modality probe, combining Raman spectroscopy and tactile resonance technology, has been used for assessment of fresh human prostate tissue. The study investigates the potential of the dual-modality probe by testing its ability to differentiate prostate tissue types ex vivo. Measurements on four prostates show that the tactile resonance modality was able to discriminate soft epithelial tissue and stiff stroma (p<0.05). The Raman spectra exhibited a strong fluorescent background at the current experimental settings. However, stroma could be discerned from epithelia by integrating the value of the spectral background. Combining both parameters by a stepwise analysis resulted in 100% sensitivity and 91% specificity. Although no cancer tissue was analysed, the results are promising for further development of the instrument and method for discriminating prostate tissues and cancer. © 2015 Informa UK Ltd. All rights reserved. Source

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