Kanimozhi Vendhan MBBS, FRCR, Abstract Co-Author: Nothing to Disclose

Timothy James Bray MBBCHIR, MA, Presenter: Nothing to Disclose

David Atkinson, Abstract Co-Author: Nothing to Disclose

Corinne Fisher, Abstract Co-Author: Nothing to Disclose

Debajit Sen, Abstract Co-Author: Nothing to Disclose

Yiannakis Ioannou, Abstract Co-Author: Nothing to Disclose

Margaret Anne Hall-Craggs MD, Abstract Co-Author: Nothing to Disclose

To develop a technique to quantify inflammation of the sacroiliac joints in adolescents with enthesitis related arthritis (ERA) using diffusion-weighted MRI.

We performed a retrospective case control study on 10 patients (5 ERA cases; 5 controls with mechanical back pain). All patients had conventional MRI of the sacroiliac joints along with diffusion weighted MRI. The anonymised images were exported to Matlab for analysis. In the cases, T1 and STIR images of the SIJs were reviewed in conjunction with the diffusion-weighted images to select the image that demonstrated the most severe inflammation of the right and left SIJs. In the controls, the slice representing the central axial image of the SIJs was selected. On these selected ADC images the synovial portion of each sacroiliac joint was divided into anterior, mid and posterior thirds. Using Matlab, a linear region of interest (ROI), measuring 14 - 16mm, and centered on the SIJ, was drawn in each third of the joint. In order to provide internal standardisation, a further linear ROI of the same measurement was placed on normal sacral bone to obtain a reference value. A custom written Matlab program was used for image analysis. The user drawn linear ROI is automatically cropped about its centre to a standardised length of 14mm. The program then creates a profile of ADC values across each of the linear ROIs. Using these profiles the normalised 'integrated ADC value' is calculated for all patients. The ‘worst’ ADC value, which is defined as the summated ADC of the region of most severe inflammation in the cases, was compared with the average 'integrated ADC value' of the controls.

The average absolute ADC value in controls was 684 x 10-6 mm2s-1 and in cases was 1211 x 10-6 mm2s-1. The difference was highly significant with a p value = 0.001. The mean 'integrated normalised ADC value' in controls was 1453 mm2s-1x mm vs 10287 mm2s-1x mm in cases (p value <0.001).  

This novel technique for quantifying SIJ inflammation shows promise and could potentially be used to monitor disease over time and to assess response to therapy.

This method has the potential to serve as a quantitative tool to assess sacroiliitis. This is useful to compare follow-up studies to assess treatment response. It also has use in clinical trials to assess drug efficacy.  

Vendhan, K, Bray, T, Atkinson, D, Fisher, C, Sen, D, Ioannou, Y, Hall-Craggs, M, Development of a Methodology to Quantify Inflammation of the Sacroiliac Joints in ERA Using ADC Maps.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14003459.html