dGEMRIC as a function of BMI

SummaryObjectiveDelayed gadolinium-enhanced MRI of cartilage (dGEMRIC) reflects cartilage glycosaminoglycan (GAG) distribution. The technique assumes that the plasma levels of the contrast agent Gd-DTPA2− are the same across individuals after intravenous (IV) injection, when dosing by weight. However, adipose tissue has lower extracellular water (ECW) than lean tissue. The aims of this study were to measure (1) plasma Gd-DTPA2− levels vs body mass index (BMI), and (2) dGEMRIC vs BMI after correcting for the dose–BMI effect.Method(1) Plasma Gd-DTPA2− levels were analyzed at 3–90min after IV injection per body weight in 24 individuals with BMI between 21.5 and 46.5. (2) dGEMRIC was compared with BMI in 19 asymptomatic volunteers and 23 with osteoarthritis (OA).Results(1) Plasma Gd-DTPA2− kinetics were similar in obese and non-obese groups, however, overall concentration was higher in the obese group. A very obese subject (BMI 45) would have 1.4 times higher Gd-DTPA2− concentration than a lean subject (BMI 20), which translates into a bias in dGEMRIC of up to 20%. (2) With dose bias taken into account, dGEMRIC showed no correlation with BMI in asymptomatic knees. In OA knees, unnarrowed femoral compartments demonstrated a negative correlation between dGEMRIC and BMI (R=0.57, P=0.004). No correlation was seen in radiographically narrowed compartments.ConclusionBMI can be a source of dosing bias in dGEMRIC and a correction factor should be considered in cross-sectional studies with a large range of BMI. There is no correlation between dGEMRIC and BMI in asymptomatic knees, but a negative correlation in OA knees

Persisting CAM deformity is associated with early cartilage degeneration after Slipped Capital Femoral Epiphysis : 11-year follow-up including dGEMRIC

Objective: Slipped capital femoral epiphysis (SCFE) in adolescence is associated with increased risk of future osteoarthritis (OA). The purpose of this study was to study clinical and radiographic risk factors for early cartilage degeneration after SCFE. Design: 22 patients (44 hips) (mean age 24 years, range 18-27) treated with in situ fixation (The Hansson hook-pin) for stable SCFE on average 11 years previously were investigated. Cartilage status was assessed with delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC). The alpha angle, reflecting femoroacetabular impingement (FAI), and the original slip angle were measured. Clinical outcome was assessed with the Copenhagen hip and groin outcome score (HAGOS) and clinical examination. Results: The dGEMRIC index was lower in SCFE hips than unaffected hips 456 ms (CI 419-493) vs 521 ms (CI 476-567) (P = 0.03). The difference was larger (mean 21 ms) in anterior than posterior regions of the hip (P = 0.038). The alpha angle was higher in SCFE hips, 61.5° (CI 53.9-69.1) vs 45.6° (CI 43.6-47.6), (P < 0.001). The alpha angle, but not the original slip angle, correlated negatively with the dGEMRIC index (R = -0.40, P = 0.046). There was a positive correlation between HAGOS and the dGEMRIC-index (R = 0.41, P = 0.012). Conclusions: Early cartilage degeneration after SCFE seems related to persisting FAI in adulthood, rather than the initial slip severity. The correlation between dGEMRIC and HAGOS indicates a clinical relevance of the MRI findings. Our results suggest that FAI after SCFE should be evaluated already after physeal closure in order to predict and possibly prevent future OA development

Assessment of osteoarthritis in hips with femoroacetabular impingement using delayed gadolinium enhanced MRI of cartilage

PURPOSE: To determine the feasibility of assessing early osteoarthritis (OA) in hips with femoroacetabular impingement (FAI) using delayed Gadolinium enhanced MRI of Cartilage (dGEMRIC). MATERIALS AND METHODS: Thirty-seven hips in 30 patients who had a dGEMRIC scan and radiographic evidence of FAI were identified. Clinical symptoms were assessed. Radiographic measurements were performed to determine acetabular and femoral morphology. The severity of radiographic OA was determined using Tönnis grade and minimum joint space width (JSW). On MRI, the alpha angle was measured on the sagittal oblique slices. Correlations between dGEMRIC index, patient symptoms, morphologic measurements, radiographic OA, and age were determined. RESULTS: Significant correlations were observed between dGEMRIC index, pain (P < 0.05), and alpha angle (P < 0.05). The correlation of dGEMRIC with alpha angle suggests that hips with more femoral deformity show signs of early OA. CONCLUSION: The results of osteoplasty for FAI depend on the amount of pre-existing OA in the joint. dGEMRIC may be a useful technique for diagnosis and staging of early osteoarthritis in hips with impingement