Role of Pelvic Magnetic Resonance Imaging for Evaluation of Disease Activity in Pediatric Patients With Perianal Crohnʼs Disease

Abstract

Approximately one-third of the patients with Crohn's Disease have perianal involvement. Cessation of drainage from the orifices of the fistula is still been used widely as an indicator for cure in the pediatric population. However, recent literature has shown us that cessation of drainage is not equivalent to healing of a fistula. Contrast-enhanced pelvic Magnetic Resonance Imaging has been used to diagnose and monitor perianal Crohn's Disease. Adult studies have used various radiologic parameters (T2 hyperintensity, rectal wall thickening, bowel stratification, Percentage Increase in T2 hyperintensity etc.) and scores (Van Assche Score) to monitor perianal Crohn's Disease. However, similar studies are lacking in pediatric population. We performed a retrospective chart review of children under the age of 18 years at initial diagnosis who underwent contrast-enhanced pelvic MRI for perianal Crohn's disease. We analyzed a total of 44 pelvic MRI images. Of those, 29 were baseline images, performed at the time of diagnosis and 15 were follow up images (while on treatment). We also noted down clinical (fistula drainage) and laboratory (hemoglobin, hematocrit, albumin, ESR and CRP). We compared various radiological parameters and scores amongst the two groups. We also compared the correlation of the radiological parameters to laboratory values at the time of MRI. We found that amongst individual parameters, the PI (percentage increase in intensity on contrast enhancement compared to fat) [2], was significantly higher in the baseline group compared to treatment group {318.97 ± 116.81 vs. 246.15 ± 74.89 P = 0.021}. There was no significant difference amongst the other individual parameters (T2 hyperintensity, rectal wall thickening, Park's classification, St James classification, presence of abscesses). However, the MRI based scores suggested by Van Assche et al [1] (15.28 ± 3.82 vs10.47 ± 4.62, P = 0.002) and Horsthius et al [1] (21.34 ± 4.74 vs 14.87 ± 6.02, P = 0.001) were significantly higher in the baseline group compared to treatment group. Also, MRI scores by Horstheus et al showed significant positive correlation to ESR (Pearson co-efficient = 0.398, P = 0.012) and negative correlation to serum albumin (Pearson co-efficient = -0.558, P = 0.00), hemoglobin (Pearson co-efficient = -0.317, P = 0.016) and hematocrit. (Pearson co-efficient = -0.383, P = 0.016). Similar results were seen with the Van Assche score. Authors suggest that the use of radiological parameters and scores described above will help the pediatric gastroenterologist to better monitor treatment of perianal Crohn's disease. To the best of authors' knowledge; this is the first study in pediatric population which demonstrates the value of using the above radiological parameters and scores to monitor perianal Crohn's disease. References 1) Horsthuis K, de Ridder L, Smets AM, van Leeuwen MS, Benninga MA, Houwen RH, et al. Magnetic resonance enterography for suspected inflammatory bowel disease in a pediatric population. J Pediatr Gastroenterol Nutr. Nov; 51(5):603-9. 2) Villa C, Pompili G, Franceschelli G, Munari A, Radaelli G, Maconi G, et al. Role of magnetic resonance imaging in evaluation of the activity of perianal Crohn's disease. Eur J Radiol. Apr; 81(4):616-22.