MR imaging of the knee in children with juvenile rheumatoid arthritis

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Quantification of dynamic contrast-enhanced MR imaging of the knee in

children with juvenile rheumatoid arthritis based on pharmacokinetic

modeling

Magnetic Resonance Imaging Vol 22,Issue 9,November 2004, Pages 1201-1210

http://www.mdlinx.com/RheumatologyLinx/thearts.cfm?artid=1126691 & specid=18 & ok=ye\

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Abstract

Improved management of arthritis requires a reliable, quantifiable,

noninvasive method to monitor the degree of inflammation and therapeutic

response during the early phase of the disease.

For this purpose, the uptake of Gd-DTPA in the distal femoral physis and

synovium in children with juvenile rheumatoid arthritis (JRA) was

evaluated with a two-compartment pharmacokinetic model and dynamic

contrast-enhanced magnetic resonance imaging (DCE-MRI). Employing a

two-compartment pharmacokinetic model, the theoretical signal

enhancement from Gd-DTPA enhanced dynamic 3D gradient-recalled echo

(GRE) images was shown to have a simple linear relationship with tissue

concentration independent of flip angle.

The signal-enhancement patterns for each individual knee were found to

be characterized by three pharmacokinetic parameters: kep (min-1), the

rate constant; kel (min-1), the elimination rate constant; and ER

(min-1), the initial enhancement rate, which is proportional to the

transfer constant Ktrans (min-1). Characteristic patterns were observed

in the image signal intensity–time course.

The initial enhancement rate, ER, in regions of interest (ROIs) was

found to have a wide range of variation: 5 to 38 min-1 over the distal

femoral physis and 1 to 10 min-1 in the synovium. The ER of the synovium

was correlated with the ER of the distal femoral physis (P<.05). In

addition, the ER of the synovium was correlated to the clinical outcome

measures of knee swelling.

Further investigation is needed to determine whether wide variations in

the pharmacokinetic parameters reflect the degree of disease activity,

and whether there are changes in response to therapy. This method can

also be applied in adults with rheumatoid arthritis (RA) and other

disorders where T1-weighted contrast is used (breast cancer, brain tumors).

Dagnachew W. Workiea, b, Bernard J. Dardzinskib, c, d, , , T. Brent

Grahame, Tal Laorc, d, A. Bommerb and Kendall J. O'Brienb

aDepartment of Physics, Cincinnati Children's Hospital Medical Center,

University of Cincinnati, Cincinnati, OH 45229-3039, USA

bImaging Research Center, Cincinnati Children's Hospital Medical Center,

Cincinnati, OH 45229-3039, USA

cDepartment of Pediatrics, Cincinnati Children's Hospital Medical

Center, Cincinnati, OH 45229-3039, USA

dDepartment of Radiology, Cincinnati Children's Hospital Medical Center,

Cincinnati, OH 45229-3039, USA

eDivision of Rheumatology, Cincinnati Children's Hospital Medical

Center, Cincinnati, OH 45229-3039, USA

Corresponding author. Imaging Research Center, Cincinnati Children's

Hospital Medical Center, Cincinnati, OH 45229-3039, USA. Tel.: +1 513

636 7721; fax: +1 513 636 3754.