Development and Validation of a Pediatric MRI-Based Perianal Crohn Disease (PEMPAC) Index—A Report from the ImageKids Study

Abstract

Background As part of the prospective multicenter ImageKids study, we aimed to develop and validate the pediatric MRI-based perianal Crohn disease (PEMPAC) index. Methods Children with Crohn disease with any clinical perianal findings underwent pelvic magnetic resonance imaging at 21 sites globally. The site radiologist and 2 central radiologists provided a radiologist global assessment (RGA) on a 100 mm visual analog scale and scored the items selected by a Delphi group of 35 international radiologists and a review of the literature. Two weighted multivariable statistical models were constructed against the RGA. Results Eighty children underwent 95 pelvic magnetic resonance imaging scans; 64 were used for derivation and 31 for validation. The following items were included: fistula number, location, length and T2 hyperintensity; abscesses; rectal wall involvement; and fistula branching. The last 2 items had negative beta scores and thus were excluded in a contending basic model. In the validation cohort, the full and the basic models had the same strong correlation with the RGA (r = 0.75; P < 0.01) and with the adult Van Assche index (VAI; r = 0.93 and 0.92; P < 0.001). The correlation of the VAI with the RGA was similar (r = 0.77; P < 0.01). The 2 models and the VAI had a similar ability to differentiate remission from active disease (area under the receiver operating characteristic curve, 0.91-0.94). The PEMPAC index had good responsiveness to change (area under the receiver operating characteristic curve, 0.89; 95% confidence interval, 0.69-1.00). Conclusions Using a blended judgmental and mathematical approach, we developed and validated an index for quantifying the severity of perianal disease in children with CD. The adult VAI may also be used with confidence in children.

Radiologist Performance and Reliability of MR Scoring Systems in Perianal Fistulizing Crohn’s Disease: Retrospective Analysis in a Real-World Clinical Practice

“…Given that MAGNIFI-CD [15] and PEMPAC [16] were developed through a combination of expert opinion and assessment of disease severity on a 100 mm visual analog scale, the strong association between the CD-PAF MR scoring systems and radiologists' subjective severity assessments is consistent with their design. However, the magnitude of change in these scores that would constitute radiological healing remains undefined without a direct correlation between pathology and imaging findings.…”

“…This study evaluated the radiologist performance characteristics of CD-PAF MR scoring systems, including MAGNIFI-CD [15], mVAI [14], and PEMPAC [16], in a real-world cohort of patients with CD-PAF who underwent serial imaging with pelvic MR. In our study design, the MR scoring systems are responsive in assessing changes in disease severity and show associations with radiologists’ subjective impressions.…”

“…Numerous scoring systems have been developed for MR of the pelvis, including the VAI [17], and the three scoring systems evaluated in this study, mVAI [14], MAGNIFI-CD [15], and PEMPAC [16]. PEMPAC was developed in a pediatric cohort of CD-PAF [16]; we incorporated this scoring system in this study to assess its performance in an adult cohort. These MR scoring systems have been incorporated into primary and secondary endpoints in CD-PAF clinical trials [21, 22].…”

“…MR scoring systems included variables in the modified Van Assche index (mVAI) [14], magnetic resonance novel index for fistula imaging in CD (MAGNIFI-CD) [15], and pediatric MR-based perianal Crohn disease (PEMPAC) index [16]. A formal calculation of the original Van Assche index (VAI) was not performed [17].…”

Clinical characteristics and MRI-based phenotypes of perianal abscess formation in children with fistulizing Crohn's Disease

“…In addition, the fistula length was significantly shorter in patients who did not form perianal abscess ( p = 0.006). A study by Choshen et al highlighted that the best imaging findings indicating the severity of pediatric perianal CD were presence of collections >3 mm, location and length of the fistulas ( 27 ). Also, a previous study on MRI predictors of treatment response in children with CPF reported that maximum fistula length ≥2.5 cm was a predictor of disease progression ( 15 ).…”