Imaging modalities for perianal Crohn's disease

Anorectal involvement in Crohn's disease (CD) causes perianal lesions that vary from simple asymptomatic skin tags, to complex disabling fistulas and abscesses. Perianal CD affects approximately one-third of patients; its management is challenging and may require combined medical and surgical treatment, which has proven to offer the best chance of success. An optimal preoperative disease assessment is crucial in order to achieve an optimal outcome and avoid irreversible damage due to incomplete or inaccurate intervention. Imaging modalities are useful in order to confirm diagnosis, to accurately classify the disease, as to plan the most suitable treatment and monitor its results. Endoscopic Ultrasonography (EUS) and pelvic Magnetic Resonance (MRI) represent the best options from this perspective, both in terms of sensitivity and specificity, as well as for their demonstrated role in influencing treatment approach. Transperineal Ultrasonography (TPUS) may be helpful when EUS is contraindicated or not-tolerated. Computed Tomography (CT) and fistulography are generally no longer considered due to their inferior performance and the radiation exposure they involve. All imaging should be done in conjunction with an Evaluation Under Anesthesia (EUA) performed by an expert surgeon, to ensure accurate disease assessment. In this paper we review available data on each imaging modality, comparing performance and focusing on specific pros and cons, in order to assist clinicians in choosing the most appropriate treatment option for each individual patient.