The purpose of this article is to provide an overview of pelvic MRI for the evaluation of perianal fistulas, with a description of the technique, illustration of relevant normal anatomy, and examples of various fistula types.
MRI evaluation of perianal fistulas can be challenging, and knowledge of relevant pelvic anatomy and fistula classification remains crucial in the diagnosis. MRI is highly accurate for fistula depiction and, by providing an accurate assessment of disease status and extension, can help surgical planning to minimize recurrence and detect clinically unapparent disease.
[Show abstract][Hide abstract] ABSTRACT: Aim of the work
To evaluate the role of magnetic resonance imaging (MRI) in preoperative assessment of ano-rectal fistula and tracing its full extent and relationship.
Materials and methods
Twenty-four patients with ano-rectal fistula were enrolled in this study. They were examined with different MRI sequences for evaluation of the fistulas and their extent. Fistulas were classified according to St. James’s University Hospital MRI based classification system (which correlates the Parks surgical classification to anatomic MRI findings) into 5 grades. Then, interrelation between surgical and MRI findings was statistically analyzed with evaluation of the accuracy of each MRI sequence used.
Grade 1 was the most frequent (37.5%) type of ano-rectal fistula. The most common location of the internal opening of the fistula was at 6 o’clock position. Combination of oblique coronal and axial planes of contrast-enhanced fat suppressed T1-weighed fast spin-echo (CE FS T1WFSE) sequence images showed the highest accuracy (99.4%) in diagnosis of ano-rectal fistula.
MRI is a useful imaging tool in the preoperative assessment of ano-rectal fistula. A significant accordance between surgical and MRI findings was achieved by using combination of coronal and axial planes of CE FS T1WFSE sequence images.
Egyptian Journal of Radiology and Nuclear Medicine 01/2013; 45(1). DOI:10.1016/j.ejrnm.2013.10.008
[Show abstract][Hide abstract] ABSTRACT: Crohn’s disease is a chronic inflammatory disease which may involve any segment of the gastrointestinal tract, most frequently the terminal ileum, the large intestine, and the perianal region. The symptoms of perianal Crohn’s disease include skin disorders, hemorrhoids, anal ulcers, anorectal stenosis, perianal abscesses and fistulas, rectovaginal fistulas and carcinoma of the perianal region. The perianal manifestations of Crohn’s disease cause great discomfort to the patient and are among the most difficult aspects to treat. Management of perianal disease requires a combination of different imaging modalities and a close cooperation between gastroenterologists and dedicated surgeons.
[Show abstract][Hide abstract] ABSTRACT: Successful anal fistula care is aided by specialized imaging accurately defining the site of the internal opening and fistula type. Imaging techniques are complementary, designed to answer specific anatomical questions. There are limited data concerning the clinical value of transperineal ultrasound (TP-US) in both cryptogenic fistula-in-ano and perianal Crohn's disease (PACD). The aim of the study was to assess the accuracy of TP-US compared with operative findings in patients with perirectal sepsis.
Patients with recurrent cryptogenic anal fistula and PACD referred for sonography were examined using TP-US by a single examiner blinded to the operative results. Fistulae were categorized by the Parks classification predicting the site of the internal fistula opening. Ancillary horseshoe collections, abscesses and secondary tracks were defined.
Fourteen patients with PACD and 27 patients with recurrent cryptogenic fistula-in-ano were analysed with comparative images and operative data. Correlation of fistula type for cryptogenic and PACD patients respectively was 23/27 (85.2%) and 12/14 (85.7%), with a correlative internal opening site (when found at surgery) of 16/22 (72.3%) and 12/14 (85.7%). Misclassification of fistula type in cryptogenic cases occurred in the presence of ancillary abscesses with associated acoustic shadowing. In PACD patients, TP-US was used when anal stenosis precluded endoanal ultrasonography, assisting in the diagnosis of recto-vaginal fistulae.
TP-US is a useful complementary technique to assess fistula-in-ano and has special advantage when there is anal canal distortion, complex fistula type or suspicion of a recto-vaginal fistula.
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