Imaging techniques and combined medical and surgical treatment of perianal Crohn’s disease. J Ultrasound. 2015;18:19-35. [PMID: 25767636 DOI: 10.1007/s40477-013-0042-9]

Practical approach to linear endoscopic ultrasound examination of the rectum and anal canal

Standard endosonographic examination of the rectal area is usually performed with radial endoscopic ultrasound (EUS). However, in recent years, widespread availability of linear EUS for assessing various anatomical regions in the gastrointestinal tract has facilitated its use in the assessment of anorectal disorders. Currently, many rectal and anal diseases, including perianal abscesses, fistulae, polyps, and neoplastic lesions, can be well-visualized and evaluated with linear EUS. The aim of this review is to shed light on the anatomy and systematic examination of the anorectal region with linear EUS and clinical implications for different anorectal pathologies.

Rectal Endoscopic Ultrasound in Clinical Practice

PURPOSE OF REVIEW

Endoscopic ultrasound (EUS) is routinely utilized for evaluation of disorders of the lower gastrointestinal tract. In this review, we summarize the current status of rectal EUS in clinical practice and describe recent developments in diagnostic and therapeutic rectal EUS.

RECENT FINDINGS

Recent guidelines recommend rectal EUS for rectal cancer staging as a second line modality in cases where MRI is contraindicated. Forward-viewing echoendoscopes and through the scope EUS miniprobes allow for EUS imaging of lesions through the entire colon and for evaluation beyond stenoses or luminal narrowings. EUS can be used to assess perianal disease and drain pelvic abscess associated with IBD, along with newer applications currently under investigation. For rectal varices, EUS can confirm the diagnosis, assess the optimal site for banding, guide therapy placement with sclerotherapy and/or coils, and assess response to treatment by confirming absence of flow. Therapeutic rectal EUS is emerging as a promising modality for drainage of pelvic fluid collection drainage and fiducial placement for rectal or prostatic cancer. Drug delivery mechanisms and substances that may increase the scope of therapy with rectal EUS are in varying stages of development. Rectal EUS continues to be an important modality for evaluation of benign and malignant disorders of the lower gastrointestinal tract, although its use as a cancer staging modality has declined due to improvements in MRI technology. Various technologies to enhance ultrasound imaging and for therapeutics have been developed that have or may contribute to expanded indications for rectal EUS.

Papel da ultrassonografia endoscópica na avaliação da fístula perianal na doença de Crohn

RESUMO Objetivo: determinar o papel da ultrassonografia endoscópica (UE) em relação à ressonância magnética nuclear (RMN) e ao exame sob anestesia (ESA) no manejo de pacientes com doença de Crohn fistulizante perianal. Métodos: estudo observacional transversal com pacientes com doença de Crohn perianal, avaliados em um centro terciário de Curitiba, Paraná, Brasil, de fevereiro de 2016 a março de 2017. Todos os pacientes foram submetidos à UE, RMN e ESA. O grau de concordância entre os três métodos foi avaliado através da obtenção do coeficiente de Kappa. Um valor de Kappa de 0,7 ou maior indicou boa concordância. O teste não paramétrico de Friedman foi utilizado para comparar o número de trajetos fistulosos detectados em cada modalidade. Considerou-se o nível de significância estatística como p<0,05. Resultados: vinte pacientes foram incluídos. Houve concordância entre os três exames em 11 pacientes. O nível de concordância de Kappa entre os três exames foi 0,53 (moderado) (p<0,001). Não houve diferença estatisticamente significativa em relação ao número de trajetos fistulosos detectados nos três exames (p=0,641). Houve falha na identificação de um trajeto fistuloso em três pacientes com a UE, em três pacientes com a RMN e em dois pacientes com o ESA. Conclusão: a UE foi comparável à RMN e ao ESA para avaliação da doença de Crohn fistulizante perianal, e pode ser considerada um exame válido para investigação pré-operatória desses pacientes.

Advances in endoscopic ultrasound imaging of colorectal diseases

The development of endoscopic ultrasound (EUS) has had a significant impact for patients with digestive diseases, enabling enhanced diagnostic and therapeutic procedures, with most of the available evidence focusing on upper gastrointestinal (GI) and pancreatico-biliary diseases. For the lower GI tract the main application of EUS has been in staging rectal cancer, as a complementary technique to other cross-sectional imaging methods. EUS can provide highly accurate in-depth assessments of tumour infiltration, performing best in the diagnosis of early rectal tumours. In the light of recent developments other EUS applications for colorectal diseases have been also envisaged and are currently under investigation, including beyond-rectum tumour staging by means of the newly developed forward-viewing radial array echoendoscope. Due to its high resolution, EUS might be also regarded as an ideal method for the evaluation of subepithelial lesions. Their differential diagnosis is possible by imaging the originating wall layer and the associated echostructure, and cytological and histological confirmation can be obtained through EUS-guided fine needle aspiration or trucut biopsy. However, reports on the use of EUS in colorectal subepithelial lesions are currently limited. EUS allows detailed examination of perirectal and perianal complications in Crohn’s disease and, as a safe and less expensive investigation, can be used to monitor therapeutic response of fistulae, which seems to improve outcomes and reduce the need for additional surgery. Furthermore, EUS image enhancement techniques, such as the use of contrast agents or elastography, have recently been evaluated for colorectal indications as well. Possible applications of contrast enhancement include the assessment of tumour angiogenesis in colorectal cancer, the monitoring of disease activity in inflammatory bowel disease based on quantification of bowel wall vascularization, and differentiating between benign and malignant subepithelial tumours. Recent reports suggest that EUS elastography enables highly accurate discrimination of colorectal adenocarcinomas from adenomas, while inflammatory bowel disease phenotypes can be distinguished based on the strain ratio calculation. Among EUS-guided therapies, the drainage of abdominal and pelvic collections has been regarded as a safe and effective procedure to be used as an alternative for the transcutaneous route, while the placing of fiducial markers under EUS guidance for targeted radiotherapy in rectal cancer or the use of contrast microbubbles as drug-delivery vehicles represent experimental therapeutic applications that could greatly impact the forthcoming management of patients with colorectal diseases, pending on further investigations.