| 1. |
- Sarve, Hamid, et al.
(författare)
-
Extracting 3D information on bone remodeling in the proximity of titanium implants in SRμCT image volumes.
- 2011
-
Ingår i: Computer methods and programs in biomedicine. - : Elsevier BV. - 1872-7565 .- 0169-2607. ; 102:1, s. 25-34
-
Tidskriftsartikel (refereegranskat)abstract
- Bone-implant integration is measured in several ways. Traditionally and routinely, 2D histological sections of samples, containing bone and the biomaterial, are stained and analyzed using a light microscope. Such histological section provides detailed cellular information about the bone regeneration in the proximity of the implant. However, this information reflects the integration in only a very small fraction, a 10 μm thick slice, of the sample. In this study, we show that feature values quantified on 2D sections are highly dependent on the orientation and the placement of the section, suggesting that a 3D analysis of the whole sample is of importance for a more complete judgment of the bone structure in the proximity of the implant. We propose features describing the 3D data by extending the features traditionally used for 2D-analysis. We present a method for extracting these features from 3D image data and we measure them on five 3D SRμCT image volumes. We also simulate cuts through the image volume positioned at all possible section positions. These simulations show that the measurement variations due to the orientation of the section around the center line of the implant are about 30%.
|
|
| 2. |
- Höglund, Odd, et al.
(författare)
-
Online dosimetry for temoporfin-mediated interstitial photodynamic therapy using the canine prostate as model
- 2016
-
Ingår i: Journal of Biomedical Optics. - 1083-3668 .- 1560-2281. ; 21
-
Tidskriftsartikel (refereegranskat)abstract
- Online light dosimetry with real-time feedback was applied for temoporfin-mediated interstitial photodynamic therapy (PDT) of dog prostate. The aim was to investigate the performance of online dosimetry by studying the correlation between light dose plans and the tissue response, i.e., extent of induced tissue necrosis and damage to surrounding organs at risk. Light-dose planning software provided dose plans, including light source positions and light doses, based on ultrasound images. A laser instrument provided therapeutic light and dosimetric measurements. The procedure was designed to closely emulate the procedure for whole-prostate PDT in humans with prostate cancer. Nine healthy dogs were subjected to the procedure according to a light-dose escalation plan. About 0.15 mg/kg temoporfin was administered 72 h before the procedure. The results of the procedure were assessed by magnetic resonance imaging, and gross pathology and histopathology of excised tissue. Light dose planning and online dosimetry clearly resulted in more focused effect and less damage to surrounding tissue than interstitial PDT without dosimetry. A light energy dose-response relationship was established where the threshold dose to induce prostate gland necrosis was estimated from 20 to 30 J/cm(2). (C) 2016 Society of Photo-Optical Instrumentation Engineers (SPIE)
|
|
| 3. |
- Buratovic, Sonja, 1986-, et al.
(författare)
-
Effects on adult cognitive function after neonatal exposure to clinically relevant doses of ionising radiation and ketamine in mice
- 2018
-
Ingår i: British Journal of Anaesthesia. - : ELSEVIER SCI LTD. - 0007-0912 .- 1471-6771. ; 120:3, s. 546-554
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Radiological methods for screening, diagnostics and therapy are frequently used in healthcare. In infants and children, anaesthesia/sedation is often used in these situations to relieve the patients' perception of stress or pain. Both ionising radiation (IR) and ketamine have been shown to induce developmental neurotoxic effects and this study aimed to identify the combined effects of these in a murine model. Methods: Male mice were exposed to a single dose of ketamine (7.5 mg kg(-1) body weight) s.c. on postnatal day 10. One hour after ketamine exposure, mice were whole body irradiated with 50-200 mGy gamma radiation (Cs-137). Behavioural observations were performed at 2, 4 and 5 months of age. At 6 months of age, cerebral cortex and hippocampus tissue were analysed for neuroprotein levels. Results: Animals co-exposed to IR and ketamine displayed significant (P <= 0.01) lack of habituation in the spontaneous behaviour test, when compared with controls and single agent exposed mice. In the Morris Water Maze test, co-exposed animals showed significant (P <= 0.05) impaired learning and memory capacity in both the spatial acquisition task and the relearning test compared with controls and single agent exposed mice. Furthermore, in co-exposed mice a significantly (P <= 0.05) elevated level of tau protein in cerebral cortex was observed. Single agent exposure did not cause any significant effects on the investigated endpoints. Conclusion: Co-exposure to IR and ketamine can aggravate developmental neurotoxic effects at doses where the single agent exposure does not impact on the measured variables. These findings show that estimation of risk after paediatric low-dose IR exposure, based upon radiation dose alone, may underestimate the consequences for this vulnerable population.
|
|
| 4. |
- Espes, Daniel, 1985-, et al.
(författare)
-
Pancreatic perfusion and its response to glucose as measured by simultaneous PET/MRI
- 2019
-
Ingår i: Acta Diabetologica. - : Springer. - 0940-5429 .- 1432-5233. ; 56:10, s. 1113-1120
-
Tidskriftsartikel (refereegranskat)abstract
- AIMS: Perfusion of the pancreas and the islets of Langerhans is sensitive to physiological stimuli and is dysregulated in metabolic disease. Pancreatic perfusion can be assessed by both positron emission tomography (PET) and magnetic resonance imaging (MRI), but the methods have not been directly compared or benchmarked against the gold-standard microsphere technique.METHODS: Pigs (n = 4) were examined by [15O]H2O PET and intravoxel incoherent motion (IVIM) MRI technique simultaneously using a hybrid PET/MRI scanner. The pancreatic perfusion was measured both at basal conditions and after intravenous (IV) administration of up to 0.5 g/kg glucose.RESULTS: Pancreatic perfusion increased by 35%, 157%, and 29% after IV 0.5 g/kg glucose compared to during basal conditions, as assessed by [15O]H2O PET, IVIM MRI, and microspheres, respectively. There was a correlation between pancreatic perfusion as assessed by [15O]H2O PET and IVIM MRI (r = 0.81, R2 = 0.65, p < 0.01). The absolute quantification of pancreatic perfusion (ml/min/g) by [15O]H2O PET was within a 15% error of margin of the microsphere technique.CONCLUSION: Pancreatic perfusion by [15O]H2O PET was in agreement with the microsphere technique assessment. The IVIM MRI method has the potential to replace [15O]H2O PET if the pancreatic perfusion is sufficiently large, but not when absolute quantitation is required.
|
|
| 5. |
- Miettinen, Arttu, et al.
(författare)
-
A non-destructive X-ray microtomography approach for measuring fibre length in short-fibre composites
- 2012
-
Ingår i: Composites Science And Technology. - : Elsevier BV. - 0266-3538 .- 1879-1050. ; 72:15, s. 1901-1908
-
Tidskriftsartikel (refereegranskat)abstract
- An improved method based on X-ray microtomography is developed for estimating fibre length distribution of short-fibre composite materials. In particular, a new method is proposed for correcting the biasing effects caused by the finite sample size as defined by the limited field of view of the tomographic devices. The method is first tested for computer generated fibre data and then applied in analyzing the fibre length distribution in three different types of wood fibre reinforced composite materials. The results were compared with those obtained by an independent method based on manual registration of fibres in images from a light microscope. The method can be applied in quality control and in verifying the effects of processing parameters on the fibre length and on the relevant mechanical properties of short fibre composite materials, e.g. stiffness, strength and fracture toughness.
|
|
| 6. |
- Kylberg, Gustaf, et al.
(författare)
-
Segmentation of virus particle candidates in transmission electron microscopy images
- 2012
-
Ingår i: Journal of Microscopy. - : Blackwell Publishing. - 0022-2720 .- 1365-2818. ; 245:2, s. 140-147
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present an automatic segmentation method that detects virus particles of various shapes in transmission electron microscopy images. The method is based on a statistical analysis of local neighbourhoods of all the pixels in the image followed by an object width discrimination and finally, for elongated objects, a border refinement step. It requires only one input parameter, the approximate width of the virus particles searched for. The proposed method is evaluated on a large number of viruses. It successfully segments viruses regardless of shape, from polyhedral to highly pleomorphic.
|
|
| 7. |
- Wernersson, Erik L. G., et al.
(författare)
-
Postprocessing method for reducing phase effects in reconstructed microcomputed-tomography data
- 2013
-
Ingår i: Optical Society of America. Journal A. - 1084-7529 .- 1520-8532. ; 30:3, s. 455-461
-
Tidskriftsartikel (refereegranskat)abstract
- With increased resolution in x-ray computed tomography, refraction adds increasingly to the attenuation signal. Though potentially beneficial, the artifacts caused by refraction often need to be removed from the image. In this paper, we propose a postprocessing method, based on deconvolution, that is able to remove these artifacts after conventional reconstruction. This method poses two advantages over existing projection-based (preprocessing) phase-retrieval or phase-removal algorithms. First, evaluation of the parameters can be done very quickly, improving the overall speed of the method. Second, postprocessing methods can be applied when projection data is not available, which occurs in several commercial systems with closed software or when projection data has been deleted. It is shown that the proposed method performs comparably to state-of-the-art methods in terms of image quality.
|
|
| 8. |
- Fanni, Giovanni, et al.
(författare)
-
Effects of gastric bypass surgery on brain connectivity responses to hypoglycemia
- 2023
-
Ingår i: Endocrine. - : Springer Nature. - 1355-008X .- 1559-0100 .- 0969-711X. ; 79:2, s. 304-312
-
Tidskriftsartikel (refereegranskat)abstract
- IntroductionRoux-en-Y gastric bypass (RYGB) leads to beneficial effects on glucose homeostasis, and attenuated hormonal counterregulatory responses to hypoglycemia are likely to contribute. RYGB also induces alterations in neural activity of cortical and subcortical brain regions. We aimed to characterize RYGB-induced changes in resting-state connectivity of specific brain regions of interest for energy homeostasis and behavioral control during hypoglycemia.MethodTen patients with BMI > 35 kg/m2 were investigated with brain PET/MR imaging during a hyperinsulinemic normo- and hypoglycemic clamp, before and 4 months after RYGB. Hormonal levels were assessed throughout the clamp. Resting-state (RS) fMRI scans were acquired in the glucose-lowering phase of the clamp, and they were analyzed with a seed-to-voxel approach.ResultsRS connectivity during initiation of hypoglycemia was significantly altered after RYGB between nucleus accumbens, thalamus, caudate, hypothalamus and their crosstalk with cortical and subcortical regions. Connectivity between the nucleus accumbens and the frontal pole was increased after RYGB, and this was associated with a reduction of ACTH (r = −0.639, p = 0.047) and cortisol (r = −0.635, p = 0.048) responses. Instead, connectivity between the caudate and the frontal pole after RYGB was reduced and this was associated with less attenuation of glucagon response during the hypoglycemic clamp (r = −0.728, p = 0.017), smaller reduction in fasting glucose (r = −0.798, p = 0.007) and less excess weight loss (r = 0.753, p = 0.012). No other significant associations were found between post-RYGB changes in ROI-to-voxel regional connectivity hormonal responses and metabolic or anthropometric outcomes.ConclusionRYGB alters brain connectivity during hypoglycemia of several neural pathways involved in reward, inhibitory control, and energy homeostasis. These changes are associated with altered hormonal responses to hypoglycemia and may be involved in the glucometabolic outcome of RYGB.
|
|
| 9. |
- Bergknut, Niklas, et al.
(författare)
-
Intervertebral disc disease in dogs - Part 1: A new histological grading scheme for classification of intervertebral disc degeneration in dogs
- 2013
-
Ingår i: Veterinary Journal. - : Elsevier BV. - 1090-0233 .- 1532-2971. ; 195, s. 156-163
-
Tidskriftsartikel (refereegranskat)abstract
- Three independent observers evaluated 35 IVDs at different stages of degeneration using the scheme. Glycosaminoglycan contents of the nucleus pulposus and macroscopic grading according to Thompson, which are considered 'gold standards' for IVD degeneration, were used to validate the scheme. Reproducibility was assessed by analysing the inter-observer reliability of all individual variables of the grading scheme, using a weighted kappa analysis. Significant correlations were found between Thompson grading and total histological score (r = 0.94; P < 0.01) and between glycosaminoglycan content and total histological score (r = -0.72; P < 0.01). Most individual histological variables showed 'moderate' to 'almost perfect' inter-observer reliability. The high correlation with the gold standards in combination with the high reproducibility indicates that the proposed histological grading scheme is reliable and objective for classification of IVD degeneration in both chondrodystrophic and non-chondrodystrophic dog breeds. (C) 2012 Elsevier Ltd. All rights reserved.
|
|
| 10. |
- Ley, Charles, et al.
(författare)
-
Detection of early osteoarthritis in the centrodistal joints of Icelandic horses: Evaluation of radiography and low-field magnetic resonance imaging
- 2016
-
Ingår i: Equine Veterinary Journal. - : Wiley. - 0425-1644 .- 2042-3306. ; 48, s. 57-64
-
Tidskriftsartikel (refereegranskat)abstract
- Reasons for performing studyValidated noninvasive detection methods for early osteoarthritis (OA) are required for OA prevention and early intervention treatment strategies.ObjectivesTo evaluate radiography and low-field magnetic resonance imaging (MRI) for the detection of early stage OA osteochondral lesions in equine centrodistal joints using microscopy as the reference standard.Study designProspective imaging of live horses and imaging and microscopy of cadaver tarsal joints.MethodsCentrodistal (distal intertarsal) joints of 38 Icelandic research horses aged 27-29 months were radiographed. Horses were subjected to euthanasia approximately 2 months later and cadaver joints examined with low-field MRI. Osteochondral joint specimens were classified as negative or positive for OA using light microscopy histology or scanning electron microscopy. Radiographs and MRIs were evaluated for osteochondral lesions and results compared with microscopy.ResultsForty-two joints were classified OA positive with microscopy. Associations were detected between microscopic OA and the radiography lesion categories; mineralisation front defect (P<0.0001), joint margin lesion (P<0.0001), central osteophyte (P = 0.03) and the low-field MRI lesion categories; mineralisation front defect (P = 0.01), joint margin lesion (P = 0.02) and articular cartilage lesion (P = 0.0003). The most frequent lesion category detected in microscopic OA positive joints was the mineralisation front defect in radiographs (28/42 OA positive joints, specificity 97%, sensitivity 67%). No significant differences were detected between the sensitivity and specificity of radiography and low-field MRI pooled lesion categories, but radiography was often superior when individual lesion categories were compared.ConclusionsEarly stage centrodistal joint OA changes may be detected with radiography and low-field MRI. Detection of mineralisation front defects in radiographs may be a useful screening method for detection of early OA in centrodistal joints of young Icelandic horses.
|
|
