Systematic protocol for assessment of the validity of BOLD MRI in a rabbit model of inflammatory arthritis at 1.5 tesla
- 155 Downloads
Blood-oxygen-level-dependent (BOLD) MRI has the potential to identify regions of early hypoxic and vascular joint changes in inflammatory arthritis. There is no standard protocol for analysis of BOLD MRI measurements in musculoskeletal disorders.
To optimize the following BOLD MRI reading parameters: (1) statistical threshold values (low, r > 0.01 versus high, r > 0.2); (2) summary measures of BOLD contrast (percentage of activated voxels [PT%] versus percentage signal difference between on-and-off signal intensities [diff_on_off]); and (3) direction of BOLD response (positive, negative and positive + negative).
Materials and methods
Using BOLD MRI protocols at 1.5 T, arthritic (n = 21) and contralateral (n = 21) knees of 21 juvenile rabbits were imaged at baseline and on days 1, 14 and 28 after a unilateral intra-articular injection of carrageenan. Nine non-injected rabbits served as external control knees (n = 18). By comparing arthritic to contralateral knees, receiver operating characteristic curves were used to determine diagnostic accuracy.
Using diff_on_off and positive + negative responses, a threshold of r > 0.01 was more accurate than r > 0.2 (P = 0.03 at day 28). Comparison of summary measures yielded no statistically significant difference (P > 0.05). Although positive + negative (AUC = 0.86 at day 28) and negative responses (AUC = 0.90 at day 28) for PT% were the most diagnostically accurate, positive + negative responses for diff_on_off (AUC = 0.78 at day 28) also had acceptable accuracy.
The most clinically relevant reading parameters included a lower threshold of r > 0.01 and a positive + negative BOLD response. We propose that diff_on_off is a more clinically relevant summary measure of BOLD MRI, while PT% can be used as an ancillary measure.
KeywordsInflammatory arthritis Rabbits Reading parameters Blood-oxygen-level-dependent MRI
This study was supported by a Seed Grant provided by the Radiological Society of North America Foundation to Dr. Andrea S. Doria. Dr. Michael W. Chan received the 2011 Comprehensive Research Experience for Medical Students (CREMS), Faculty of Medicine, University of Toronto Summer Studentship Award for the conduct of the data analysis of this study.
Conflicts of interest
- 8.Beukelman T, Patkar NM, Saag KG et al (2011) 2011 American College of Rheumatology recommendations for the treatment of juvenile idiopathic arthritis: initiation and safety monitoring of therapeutic agents for the treatment of arthritis and systemic features. Arthritis Care Res 63:465–482CrossRefGoogle Scholar
- 14.Howe F, Robinson S, Rijken PJFW et al (2002) Determination of tumor vascular morphology and function by susceptibility MRI and immunohistochemistry. Proc Intl Soc Mag Reson Med 10Google Scholar
- 27.Altman D (1991) Practical statistics for medical research. Chapman & Hall, London, pp 132–145Google Scholar
- 29.Riegelman R, Hirsch R (1996) Studying a study and testing a test: how to read the health science literature, 3rd edn. Little, Brown and Company, BostonGoogle Scholar
- 31.Rahim H, Ibrahim F, Taib M (2008) Model order selection criterion for monitoring haemoglobin status in dengue patients using ARX model. Information Technology and Applications in Biomedicine International Conference 2008. doi:10.1109/ITAB.2008.4570537
- 39.Sohn J, Kim Y, Lee K et al (2002) An fMRI study to identify the brain structure for predicting the level of individual’s intelligence. Neuroimage 16:1024Google Scholar