| 1. |
- Tiderius, Carl Johan
(författare)
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Contrast-enhanced MRI of human knee cartilage Clinical applications of the novel dGEMRIC technique to study glycosaminoglycan content in articular cartilage
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) is a new technique to study cartilage glycosaminoglycan (GAG) content. The negatively charged contrast agent Gd-DTPA2-, injected intravenously, distributes in the cartilage inversely to the likewise negatively charged GAG. The GAG concentration is reflected by the MRI parameter T1 and the Gd-DTPA2- concentration by the MRI parameter R1 (R1=1/T1). We have made T1 and R1 analyses in standardized regions of interest (ROIs) in lateral and medial femoral weight-bearing cartilage. In paper I, the distribution of Gd-DTPA2- (R1) in 19 healthy volunteers was linearly dose-related after injection of three different doses, showing that no active transportation is involved. The highest R1 was registered two hours post-contrast, suggesting this time as optimal in the clinical situation. Results indicated that the highest dose (triple dose: 0.3 mmol/kg body weight) is most sensitive to minor GAG differences and the triple dose was used in papers II-V. In paper II, 17 knees in 15 patients with normal x-ray but arthroscopically verified fibrillations in the medial or lateral femoral cartilage were investigated. R1 was higher in the diseased compartment after both 1.5 and 3 hours, with the greatest difference (31%) after 1.5 hours. In paper III, T1 was compared in 37 healthy volunteers with different levels of physical activity. Elite runners had 12% longer T1 than moderately exercising individuals, who in turn had 11% longer T1 than sedentary individuals. Results suggest that human knee cartilage adapts to exercise by increasing its GAG content. In paper IV, six investigators performed repeated ROI analyses in 12 volunteers. The intra- and inter-observer variability was low (C.V. less than 2.6%) with our standardized ROI drawing technique. In paper V, we combined GAG analysis of cartilage (dGEMRIC two hours post-contrast) and synovial fluid (biochemical) in 24 patients with an acute anterior cruciate ligament (ACL) rupture. Patients were investigated 3 weeks after the ACL injury and compared with 24 healthy controls. 22/24 patients had contusions of the lateral femoral cartilage, where T1 was 14% shorter than in controls. However, T1 was 12% shorter than controls also in the medial femoral cartilage, indicating that an ACL injury initiates a global loss of GAG from knee cartilage. The GAG concentration in the synovial fluid was increased in the ACL patients and showed a tendency to have a positive correlation with T1. In conclusion, the results of this thesis support dGEMRIC as a sensitive method to detect clinically relevant GAG differences in both healthy and diseased cartilage.
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| 2. |
- Tiderius, Carl Johan, et al.
(författare)
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Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) in early knee osteoarthritis.
- 2003
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Ingår i: Magnetic Resonance in Medicine. - : Wiley. - 1522-2594 .- 0740-3194. ; 49:3, s. 488-492
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Tidskriftsartikel (refereegranskat)abstract
- Delayed contrast-enhanced MRI of cartilage (dGEMRIC) is a noninvasive technique to study cartilage glycosaminoglycan (GAG) content in vivo. This study evaluates dGEMRIC in patients with preradiographic degenerative cartilage changes. Seventeen knees in 15 patients (age 35-70) with arthroscopically verified cartilage changes (softening and fibrillations) in the medial or lateral femoral compartment, knee pain, and normal weight-bearing radiography were included. MRI (1.5 T) was performed precontrast and at 1.5 and 3 hr after an intravenous injection of Gd-DTPA2- at 0.3 mmol/kg body weight. T1 measurements were made in regions of interest in medial and lateral femoral cartilage using sets of five turbo inversion recovery images. Precontrast, R1 (R1 = 1/T1, 1/s) was slightly lower in diseased compared to reference compartment, indicating increased hydration (P = 0.01). Postcontrast, R1 was higher in diseased than in reference compartment at 1.5 hr, 3.45 ± 0.90 and 2.64 ± 0.58 (mean ± SD), respectively (P < 0.01), as well as at 3 hr, 2.94 ± 0.60 and 2.50 ± 0.37, respectively (P = 0.01). The washout of the contrast medium was faster in diseased cartilage as shown by a higher R1 at 1.5 than at 3 hr in the diseased but not in the reference compartment. In conclusion, dGEMRIC can identify GAG loss in early stage cartilage disease with a higher sensitivity at 1.5 than 3 hr.
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| 3. |
- Tiderius, Carl Johan, et al.
(författare)
-
Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC): intra- and interobserver variability in standardized drawing of regions of interest.
- 2004
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Ingår i: Acta Radiologica. - : SAGE Publications. - 1600-0455 .- 0284-1851. ; 45:6, s. 628-634
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To establish the reproducibility of a standardized region of interest (ROI) drawing procedure in delayed gadolinium‐enhanced magnetic resonance imaging (MRI) of cartilage (dGEMRIC). Material and Methods: A large ROI in lateral and medial femoral weight‐bearing cartilage was drawn in images of 12 healthy male volunteers by 6 investigators with different skills in MRI. The procedure was done twice, with a 1‐week interval. Calculated T1‐values were evaluated for intra‐ and interobserver variability. Results: The mean interobserver variability for both compartments ranged between 1.3% and 2.3% for the 6 different investigators without correlation to their experience in MRI. Post‐contrast intra‐observer variability was low in both the lateral and the medial femoral cartilage, 2.6% and 1.5%, respectively. The larger variability in lateral than in medial cartilage was related to slightly longer and thinner ROIs. Conclusion: Intra‐observer variability and interobserver variability are both low when a large standardized ROI is used in dGEMRIC. The experience of the investigator does not affect the variability, which further supports a clinical applicability of the method.
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| 4. |
- Tiderius, Carl Johan, et al.
(författare)
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dGEMRIC (delayed gadolinium-enhanced MRI of cartilage) indicates adaptive capacity of human knee cartilage.
- 2004
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Ingår i: Magnetic Resonance in Medicine. - : Wiley. - 1522-2594 .- 0740-3194. ; 51:2, s. 286-290
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Tidskriftsartikel (refereegranskat)abstract
- Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) is a new imaging technique to estimate joint cartilage glycosaminoglycan content by T1-relaxation time measurements after penetration of the hydrophilic contrast agent Gd-DTPA2-. This study compares dGEMRIC in age-matched healthy volunteers with different levels of physical activity: Group 1 (n = 12): nonexercising individuals; Group 2 (n = 16): individuals with physical exercise averaging twice weekly; Group 3 (n = 9): male elite runners. dGEMRIC was performed 2 hr after an intravenous injection of Gd-DTPA2- at 0.3 mmol/kg body weight. T1 differed significantly between the three different levels of physical exercise. T1 values (mean of medial and lateral femoral cartilage) for Groups 1, 2, and 3 were: 382 ± 33, 424 ± 22 and 476 ± 36, respectively (ms, mean ± SD) (P = 0.0004, 1 vs. 2 and 0.0002, 2 vs. 3). Irrespective of the exercise level, T1 was longer in lateral compared to medial femoral cartilage (P = 0.00005; n = 37). In conclusion, this cross-sectional study indicates that human knee cartilage adapts to exercise by increasing the glycosaminoglycan content. Furthermore, results suggest a compartmental difference within the knee with a higher glycosaminoglycan content in lateral compared to medial femoral cartilage. A higher proportion of extracellular water, i.e., larger distribution volume, may to some extent explain the high T1 in the elite runners.
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