Pharmacokinetic MR analysis of the cartilage is influenced by field strength.
OBJECTIVE
To study if the pharmacokinetic parameters derived from dynamic contrast-enhanced magnetic resonance (DCE-MR) images of the patellar cartilage are influenced by the main magnetic field strength.


METHODS
DCE-MR images of the knee were obtained from 16 normal male subjects (eight cases in each 1.5 and 3T magnets). Also, four volunteers were evaluated in both equipments within 1 week. Cartilage pharmacokinetic parameters of vascular permeability (K(trans)), extraction ratio (k(ep)), extravascular extracellular space volume fraction (v(e)) and intravascular space volume fraction (v(p)) were obtained.


RESULTS
Statistically significant differences were observed between the 1.5 and 3T groups for K(trans) (mean+/-S.D.; 5.44+/-2.27 vs. 1.01+/-0.41, respectively) and v(e) (3.37+/-2.32 vs. 0.81+/-0.80). A difference in K(trans) was also present when the same controls were evaluated in both equipments. There were no significant differences for k(ep) and v(p) values. Reproducibility of the pharmacokinetic calculations, assessed with the 24 acquisitions, showed a very low test-retest root mean square coefficient of variation (0.13, 0.10, 0.23 and 0.18 for K(trans), k(ep), v(e) and v(p), respectively).


CONCLUSIONS
Cartilage vascular permeability values are influenced by the MR field strength. This should be taken in consideration when analyzing this biomarker.
Martí-Bonmatí
Luis
L
Radiology Department, Hospital Quirón Valencia, Spain. Luis.Marti@uv.es
Sanz-Requena
Roberto
R
Alberich-Bayarri
Angel
A
D000328:Adult; D002358:Cartilage, Articular / Q000033:anatomy & histology* / Q000378:metabolism*; D003287:Contrast Media / Q000493:pharmacokinetics; D004307:Dose-Response Relationship, Radiation; D005260:Female; D019786:Gadolinium DTPA / Q000493:pharmacokinetics*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D007719:Knee Joint / Q000033:anatomy & histology* / Q000378:metabolism*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008657:Metabolic Clearance Rate; D011829:Radiation Dosage; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult
D003287:Contrast Media; C064925:gadodiamide; D019786:Gadolinium DTPA