CT Pelvis If present, perianal disease may be identified within the field of view during acquisition if CTE is used for diagnosis, acute exacerbation, or therapy response. There is, however, insufficient literature to support primary imaging of perianal disease by pelvic CT. Fluoroscopy Contrast Enema Fluoroscopy contrast enema is uncommonly used in current practice. There is insufficient pediatric literature to support routine use for perianal Crohn disease. MRI Pelvis Because of the superior soft-tissue resolution allowing anatomic localization of penetrating disease in relation to the sphincteric musculature and perianal soft tissues, MRI pelvis with IV contrast is the study of choice for assessing perianal Crohn disease [5,6]. MRI of the pelvis in this setting is primarily acquired with higher-resolution T2- weighted fat-suppressed sequences and postgadolinium T1-weighted fat-suppressed images. Imaging in the axial and coronal planes may be obliqued to the anal canal depending upon institutional preference. Diagnostic performance of MRI pelvis with gadolinium may be as high as 81% sensitive and 100% specific in children [5]. Also, an adult meta-analysis of four studies showed MRI sensitivity and specificity for fistula detection were 87% and 69%, respectively, with greater specificity than US at 43% [57]. With standard pediatric MRE, which included this region, the sensitivity and specificity were 82% and 100% for perianal disease [58]. Unlike MRE, however, for MRI pelvis in this variant, oral contrast material is not necessary. There is little literature to specifically support pelvic MRI without IV contrast for perianal Crohn disease. However, noncontrast MRI will likely still yield diagnostic information for monitoring therapy response, whereas optimal anatomic distribution has previous been ascertained [6]. Pelvic MRI with contrast can also assist in predicting and monitoring treatment response.
Crohn Disease Child. CT Pelvis If present, perianal disease may be identified within the field of view during acquisition if CTE is used for diagnosis, acute exacerbation, or therapy response. There is, however, insufficient literature to support primary imaging of perianal disease by pelvic CT. Fluoroscopy Contrast Enema Fluoroscopy contrast enema is uncommonly used in current practice. There is insufficient pediatric literature to support routine use for perianal Crohn disease. MRI Pelvis Because of the superior soft-tissue resolution allowing anatomic localization of penetrating disease in relation to the sphincteric musculature and perianal soft tissues, MRI pelvis with IV contrast is the study of choice for assessing perianal Crohn disease [5,6]. MRI of the pelvis in this setting is primarily acquired with higher-resolution T2- weighted fat-suppressed sequences and postgadolinium T1-weighted fat-suppressed images. Imaging in the axial and coronal planes may be obliqued to the anal canal depending upon institutional preference. Diagnostic performance of MRI pelvis with gadolinium may be as high as 81% sensitive and 100% specific in children [5]. Also, an adult meta-analysis of four studies showed MRI sensitivity and specificity for fistula detection were 87% and 69%, respectively, with greater specificity than US at 43% [57]. With standard pediatric MRE, which included this region, the sensitivity and specificity were 82% and 100% for perianal disease [58]. Unlike MRE, however, for MRI pelvis in this variant, oral contrast material is not necessary. There is little literature to specifically support pelvic MRI without IV contrast for perianal Crohn disease. However, noncontrast MRI will likely still yield diagnostic information for monitoring therapy response, whereas optimal anatomic distribution has previous been ascertained [6]. Pelvic MRI with contrast can also assist in predicting and monitoring treatment response.