| 61. |
- Olivecrona, Lotta, et al.
(författare)
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Acetabular component migration in total hip arthroplasty using CT and a semiautomated program for volume merging
- 2002
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Ingår i: Acta Radiologica. - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 43:5, s. 517-527
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To develop a non-invasive method for detection of acetabular cup migration after total hip arthroplasty (THA) with a higher degree of accuracy than routine plain radiography. Material and Methods: Two CT examinations, 10 min apart, were obtained from each of 10 patients that had undergone THA. Using an in-house developed semiautomated program for volume merging, the pelves in the two examinations were fused and the acetabular cup was visually and numerically evaluated to test the method's accuracy in detecting migration. Results: In the visual evaluation of the best match a 1-mm translation of the cup was detectable. The numerical evaluation, comparing landmarks placed in the images of the acetabular cup and the head of the femur component in the two examinations, showed the mean difference in orientation of acetabular axes to be 2.5degrees, the mean distance between centre of cup face to be 2.5 mm and the mean distance between centre of the head of the prosthetic femoral component to be 1 mm. Conclusion: This method has a significantly higher accuracy than routine plain radiography in detecting acetabular cup migration and could be used in clinical practice. It gives both a visual and a numerical correlate to migration.
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| 62. |
- Olivecrona, Lotta, et al.
(författare)
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Model studies on acetabular component migration in total hip arthroplasty using CT and a semiautomated program for volume merging
- 2003
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Ingår i: Acta Radiologica. - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 44:4, s. 419-429
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Validation of a non-invasive CT method for detection of acetabular cup migration after total hip arthroplasty in a phantom study. Material and Methods: 26 CT examinations were obtained of a pelvic model while altering the position of the acetabular cup. Using a previously described program for volume merging, the pelvi in different examinations were fused and the 3D alterations of the position of the acetabular cup were evaluated visually and numerically and correlated to direct measurements on the model. Results: Visually, two independent examiners differentiated between 0, 1 and 2 to 3 mm migration with 100% specificity and sensitivity. Numerically, the mean error over all cases between model and CT measurements was 0.04 mm (SD +/- 0.33). The mean absolute error between model and CT data was 0.26 mm (SD +/- 0.19). Intra- and interobserver 95% accuracy and repeatability limits were below 0.5/0.7 mm, respectively. No significant interobserver difference occurred. The data were normally distributed and not dependent on observer. Conclusion: The accuracy of this non-invasive method out-performs routine plain radiography. The method gives both visual and numerical correlates to migration and can be used in clinical practice.
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| 63. |
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| 64. |
- Saarakkala, Simo, et al.
(författare)
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Ultrasound indentation of normal and spontaneously degenerated bovine articular cartilage.
- 2003
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Ingår i: Osteoarthritis and Cartilage. - : Saunders Elsevier. - 1063-4584 .- 1522-9653. ; 11:9, s. 697-705
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: We have previously developed a handheld ultrasound indentation instrument for the diagnosis of cartilage degeneration. The instrument has been demonstrated to be capable of quantifying mechanical and acoustic properties of enzymatically degraded and normal bovine articular cartilage in vitro and in situ. The aim of this study was to investigate the sensitivity of the instrument to distinguish between normal and spontaneously degenerated (e.g., in osteoarthrosis) articular cartilage in vitro.DESIGN: Thirty articular cartilage samples were prepared from the bovine lateral patellae: 19 patellae with different degenerative stages and 11 patellae with visually normal appearance. Cartilage thickness, stiffness (dynamic modulus) and ultrasound reflection from the cartilage surface were measured with the handheld instrument. Subsequently, biomechanical, histological and biochemical reference measurements were conducted.RESULTS: Reproducibility of the measurements with the ultrasound indentation instrument was good. Standardized coefficient of variation was < or =6.1% for thickness, dynamic modulus and reflection coefficient. Linear correlation between the dynamic modulus, measured with the ultrasound indentation instrument, and the reference dynamic modulus was high (r=0.993, n=30, P<0.05). Ultrasound reflection coefficient, as determined from the cartilage surface, showed high linear correlations (typically r(2)>0.64, n=30, P<0.05) with the cartilage composition and histological or mechanical properties. The instrument was superior compared to visual evaluation in detecting tissue degeneration.CONCLUSION: This study indicates that the ultrasound indentation technique and instrument may significantly improve the early diagnosis of cartilage degeneration. The results revealed that visual evaluation is insensitive for estimating the structural and mechanical properties of articular cartilage at the initial stages of degeneration.
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| 65. |
- Sahlman, Janne, et al.
(författare)
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A human COL2A1 gene with an Arg519Cys mutation causes osteochondrodysplasia in transgenic mice.
- 2004
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Ingår i: Arthritis and Rheumatism. - : John Wiley & Sons. - 0004-3591 .- 1529-0131. ; 50:10, s. 3153-3160
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: An arginine-to-cysteine substitution at position 519 of the COL2A1 gene causes early generalized osteoarthritis with mild chondrodysplasia in humans. In this study, a human COL2A1 gene with the same mutation was introduced into a murine genome having 1 or no alleles of the murine Col2a1 gene, and the skeletal phenotypes of the transgenic mice were compared with those of control mice.METHODS: Mice with 1 allele of the normal murine Col2a1 gene and 1 allele of the mutated human COL2A1 gene (n = 10), those with no murine Col2a1 gene and 2 alleles of the mutated human COL2A1 gene (n = 13), those with no murine Col2a1 gene and only 1 allele of the mutated COL2A1 gene (n = 9), and normal control mice (n = 11) were studied for skeletal abnormalities, using radiographic imaging and light microscopic analyses of histologic sections. The collagen network of cartilage was also investigated with transmission electron microscopy.RESULTS: At 2 months of age, all transgenic mice had dysplastic changes in their long bones, flattened vertebral bodies, and osteoarthritic changes in their joints. The intervertebral discs of the transgenic animals were degenerated, and their histologic structure was disturbed. The changes were more severe in mice with no murine Col2a1 allele.CONCLUSION: The human COL2A1 gene with the Arg519Cys mutation causes osteochondrodysplasia in mice, as it does in humans.
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| 66. |
- Sundgren, P C, et al.
(författare)
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Serial investigation of perfusion disturbances and vasogenic oedema in hypertensive encephalopathy by diffusion and perfusion weighted imaging.
- 2002
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Ingår i: Neuroradiology. - : Springer Science and Business Media LLC. - 1432-1920 .- 0028-3940. ; 44:4, s. 299-304
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Tidskriftsartikel (refereegranskat)abstract
- Serial MRI including diffusion and perfusion imaging was performed in a patient with hypertensive encephalopathy. At admission, the patient was disorientated and presented with seizures and cortical blindness. Perfusion imaging showed a marked reduction in blood volume and flow, with corresponding vasogenic oedema in the occipital, posterior temporal, and, to a lesser extent, frontal lobes. The clinical symptoms disappeared rapidly following treatment, whereas the disturbed circulation pattern and vasogenic oedema resolved more slowly. A complete normalisation was seen after 1 year.
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| 67. |
- Sundgren, PC, et al.
(författare)
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Carotid artery stenosis: contrast-enhanced MR angiography with two different scan times compared with digital subtraction angiography
- 2002
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Ingår i: Neuroradiology. - : Springer Science and Business Media LLC. - 1432-1920 .- 0028-3940. ; 44:7, s. 592-599
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Tidskriftsartikel (refereegranskat)abstract
- Contrast enhanced magnetic resonance angiography (CE MRA) is a non-invasive alternative to conventional digital subtraction angiography (DSA). CE MRA is increasingly used as a complement to Duplex in the preoperative assessment of carotid artery stenosis. The purpose of this study was to determine if CE MRA could replace preoperative DSA. CE MRA with a scan time of 10 or 28 s was performed in 24 consecutive patients who were scheduled for preoperative DSA because of Duplex-verified severe carotid artery stenosis. Two neuroradiologists measured the degree of stenosis with three different methods, and the image quality was evaluated. DSA was used as the gold standard. For detection of severe stenosis (N. American symptomatic carotid endarterectomy trial (NASCET) greater than or equal to70%; European symptomatic carotid endarterectomy trial (ECST) greater than or equal to80%; common carotid artery method (CCAM) greater than or equal to80%), the sensitivity of CE MRA maximum intensity projection (MIP) compared with DSA was 82%-100%, the specificity was 74%-93% and the accuracy was 77%-90%. The inter-observer agreement was higher, the image quality was better and the intracranial main arteries were better visualized with the 28 s than with the 10 s scan time. The enhancement of the jugular veins seen in 17% of the 10 s scans and in 58% of the patients with the 28 s scans did not interfere with the evaluation of the carotid arteries. CE MRA, preferably with a scan time of 28 s, can replace DSA in the preoperative assessment of most patients with carotid artery stenosis.
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| 68. |
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| 69. |
- Tallini, G, et al.
(författare)
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Correlation between clinicopathological features and karyotype in 100 cartilaginous and chordoid tumours. A report from the Chromosomes and Morphology (CHAMP) Collaborative Study Group
- 2002
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Ingår i: Journal of Pathology. - : Wiley. - 0022-3417. ; 196:2, s. 194-203
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Tidskriftsartikel (refereegranskat)abstract
- The evaluation of chondroid lesions requires full integration of clinical, radiographic, and pathological data; tumour typing is often a challenge for the diagnostic pathologist. Although a variety of chromosomal abnormalities have been documented in chondroid lesions, the potential usefulness of cytogenetic analysis remains unclear. This study has critically reviewed and analysed 117 karyotyped samples from 100 patients with cartilaginous and chordoid tumours. Cases were selected based on successful chromosomal analysis and adequacy of clinical, radiographic, and pathological information. To ensure objective evaluation, the cytogenetic results were correlated in a double-blind setting with consensus diagnoses independently determined on each case, after complete review of the histological, radiographic, and clinical findings. Karyotypic aberrations were identified in 41/92 cartilaginous tumours (5/11 osteochondromas, 2/3 chondromyxoid fibromas, 0/4 chondroblastomas, 11/29 chondromas, 0/3 chondroid tumours of undetermined malignant potential, 22/40 chondrosarcomas and 1/2 miscellaneous cartilaginous lesions) and 5/8 chordomas. Complex karyotypic changes were a feature of malignant tumours (chondrosarcoma and chordoma) and of chondrosarcoma among cartilaginous tumours, where they correlated with high tumour grade. Among primary well-differentiated cartilaginous lesions of bone, the finding of an abnormal karyotype was consistently associated with a grade 1 chondrosarcoma diagnosis. Among karyotypically abnormal cartilaginous tumours, loss of distal 8q was associated with osteochondroma, +5 with synovial chondroma/chondromatosis and parosteal or soft tissue chondroma, alterations of chromosome arm 6q with chondromyxoid fibroma, +7 with bone chondrosarcoma, and 17pl alterations with grade 3 chondrosarcoma. Alterations involving 12q13 characterized synovial chondroma/chondromatosis in the chondroma group and myxoid chondrosarcoma of bone in the chondrosarcoma group. In conclusion, cytogenetic abnormalities in chondroid lesions are common and are not randomly distributed. They are associated with malignancy/tumour grade as well as with specific diagnoses in many cases, and can therefore be of potential value for tumour typing.
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| 70. |
- Trulsson, M, et al.
(författare)
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Cortical responses to single mechanoreceptive afferent microstimulation revealed with fMRI
- 2001
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Ingår i: NeuroImage. - : Academic Press. - 1053-8119 .- 1095-9572. ; 13:4, s. 613-622
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Tidskriftsartikel (refereegranskat)abstract
- The technique of intraneural microneurography/microstimulation has been used extensively to study contributions of single, physiologically characterized mechanoreceptive afferents (MRAs) to properties of somatosensory experience in awake human subjects. Its power as a tool for sensory neurophysiology can be greatly enhanced, however, by combining it with functional neuroimaging techniques that permit simultaneous measurement of the associated CNS responses. Here we report its successful adaptation to the environment of a high-field MR scanner. Eight median-nerve MRAs were isolated and characterized in three subjects and microstimulated in conjunction with fMRI at 3.0 T. Hemodynamic responses were observed in every case, and these responses were robust, focal, and physiologically orderly. The combination of fMRI with microstimulation will enable more detailed studies of the representation of the body surface in human somatosensory cortex and further studies of the relationship of that organization to short-term plasticity in the human SI cortical response to natural tactile stimuli. It can also be used to study many additional topics in sensory neurophysiology, such as CNS responses to additional classes of afferents and the effects of stimulus patterning and unimodal/crossmodal attentional manipulations. Finally, it presents unique opportunities to investigate the basic physiology of the BOLD effect and to compare the operating characteristics of fMRI and EEG as human functional neuroimaging modalities in an unusually specific and well-characterized neurophysiological setting.
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