Quantitative Magnetic Resonance Imaging in Perianal Crohn’s Disease at 1.5 and 3.0 T: A Feasibility Study

Abstract

Perianal Crohn’s Disease (pCD) is a common manifestation of Crohn’s Disease. Absence of reliable disease measures makes disease monitoring unreliable. Qualitative MRI has been increasingly used for diagnosing and monitoring pCD and has shown potential for assessing response to treatment. Quantitative MRI sequences, such as diffusion-weighted imaging (DWI), dynamic contrast enhancement (DCE) and magnetisation transfer (MT), along with T2 relaxometry, offer opportunities to improve diagnostic capability. Quantitative MRI sequences (DWI, DCE, MT and T2) were used in a cohort of 25 pCD patients before and 12 weeks after biological therapy at two different field strengths (1.5 and 3 T). Disease activity was measured with the Perianal Crohn’s Disease Activity index (PDAI) and serum C-reactive protein (CRP). Diseased tissue areas on MRI were defined by a radiologist. A baseline model to predict outcome at 12 weeks was developed. No differences were seen in the quantitative MR measured in the diseased tissue regions from baseline to 12 weeks; however, PDAI and CRP decreased. Baseline PDAI, CRP, T2 relaxometry and surgical history were found to have a moderate ability to predict response after 12 weeks of biological treatment. Validation in larger cohorts with MRI and clinical measures are needed in order to further develop the model.

Imaging in inflammatory bowel disease: current and future perspectives

“…These include the use of MT imaging which shows promise at differentiating active from inactive fistulas by observing differences in fibrosis36 and DCE imaging which looks to model the uptake of the gadolinium contrast in the fistula tissue to assess the degree of inflammation 37. More recently quantitative T2 imaging has been applied to pCD with this parameter showing promise of predicting response to treatment when combined with other known influencing factors such as surgery, fistula complexity and baseline CRP levels 38. Although these newer sequences are not currently used clinically and take more time to setup and postprocess, their objective outcomes could allow for a more thorough investigation of the fistulas and better comparison when monitoring over longer time periods.…”

“…An area where more research and development is necessary is the visualisation and tracking of the fistulas in 3D. Simple volume measurements have been carried out showing changes with treatment,38 but there is currently no software available to assist the radiologist in defining and viewing the fistula in 3D. This has implications for quantitative imaging as well; with the ability to define the whole fistula tract from a previous scan allowing better comparison of quantitative parameters over the same region and not limiting to what was visible at the time of the current scan only.…”