Pixel-by-Pixel analysis of Dynamic Contrast-enhanced MRI curve patterns in Juvenile Idiopathic Arthritis

Juvenile Idiopathic Arthritis (JIA) is one of the most common chronic diseases
in childhood and represents one of the leading causes of pediatric acquired
disability. It is characterized by prolonged synovial inflammation that can
lead to destruction of joints, pain and loss of function. The increasing
evidence that early therapeutic intervention improves long-term outcome and the
development of effective treatments highlight the need for objective and
accurate measures in the assessment of disease activity, individual response to
therapy, efficacy of treatment and longer term outcomes in JIA.
At this moment evaluation of disease activity is done by a complete work-up
comprised of clinical history, physical examination, laboratory assessments and
imaging studies. Magnetic Resonance Imaging (MRI) is considered the superior
imaging technique assessing disease activity of the joints, using intravenous
Gadolinium (Gd) contrast which accurately shows presence, extension and
localization of inflammatory joint disease. Gd is an extracellular contrast
agent that rapidly passes from the vasculature into the
extravascular-extracellular space and in that way produces synovial
enhancement, which is associated with disease activity. Dynamic
Contrast-Enhanced MRI (DCE-MRI) is the preferred method to objectively
determine the enhancement after administration of intravenous contrast medium.
In DCE-MRI, images are acquired during the delivery of contrast in the tissue
of interest, highlighting the dynamic response of the tissue to the inflow of
blood. DCE-MRI can provide valuable information about disease activity by
analyzing the Time Intensity Curve (TIC) shapes and distribution patterns of
TICs in the synovial membrane.
Previous study of the AMC radiology group has shown that DCE-MRI can be used to
distinguish patients with Rheumatoid Arthritis (RA) from control subjects, as
correlations were found between clinically active disease and more quickly
enhancing pixels, meaning a stronger vascularization in RA patients. Therefore,
we expect that this new semi-quantitative analysis method show different TIC
shape distribution patterns in different stages of disease activity in JIA
patients and, therefore, can provide valuable information about disease
activity.

The primary objective is:
* to assess the accuracy of DCE-MRI in detecting joint inflammation as compared
to physical examination in the evaluation of different stages of disease
activity in JIA patients
The secondary objectives are:
* to evaluate the value of DCE-MRI in predicting the clinical course in 1 year
time in JIA patients
* to evaluate the enhanced value and reliability of DCE-MRI as compared to
static contrast-enhanced MRI in detecting synovial inflammation in JIA
* to evaluate the correlation between DCE-MRI parameters and laboratory
assessments of inflammatory parameters.

Prospective observational

Patients will undergo a complete work-up comprising of clinical history,
physical examination, laboratory assessments, radiographs and an open-bore
MRI-scan with intravenous contrast medium as part of their clinical
investigation:
1. An additional dynamic sequence will be added to the regular MRI scan (extra
scan time 7 minutes).
2. An additional 10 milliliters of blood will be taken during standard blood
sampling.
No side-effects or risks have been reported on MR imaging, provided
contraindications are taken in consideration. As intravenous contrast medium is
given, patients can have EMLA cream (lidocaïne and prilocaïne, Astra Zeneca,
the Netherlands) to anaesthetize the skin before insertion of the standard
intravenous cannula