Learning objectives
To provide an overview on the evaluation of perianal fistulas and to describe the typical MRI findings of the various types of fistulas with their classification.
Background
Perianal fistula is an inflammatory condition that affects the region around the anal canal.
It is characterized by a connection between the anal canal and the skin of the perineum.
Perianal fistulization is an uncommon process,
with a prevalence of 0.01%,
although it causes significant morbidity and often requires repeated surgical treatments due to its high tendency to recur.
It predominantly affects young males,
with a male-to-female ratio of 2:1.
The most common presenting symptom is discharge (65% of cases),
but local pain due to...
Findings and procedure details
The major MRI indication in perianal fistula is preoperative classification.
MRI allows a direct visualization of the fistolous tracts and abscesses,
combined with high soft tissue resolution.
MRI help to classify accurately fistolous tracts but also to identify the entire extention of the disease that otherwise would have been missed.
The most appropriate MR protocol used for evaluation of perianal fistulas consists of: oblique axial T1 and T2-weighted FSE,
oblique axial and coronal fat-suppressed T1 and T2-weighted FSE,
oriented perpendicular or parallel to the long...
Conclusion
MRI plays a crucial role in preoperative evaluation of perianal fistula,
providing accurate definition of the fistulous track,
its extension,
its relationship to pelvic structures,
and identification of secondary fistulas or abscesses.
MR imaging provides accurate information for appropriate surgical treatment,
decreasing the incidence of recurrence and allowing side effects such as fecal incontinence to be avoided [5].
By using the St James’s University Hospital classification,
an MR imaging–based grading system validated by surgical exploration and longterm clinical outcome,
the radiologist can alert the referring...
Personal information
Dr.
Maria Roberta Vaccaro Notte,
Dipartimento di Scienze Radiologiche,
Di.Bi.Med.,
Università di Palermo,
Via del Vespro 127,
90100,
Palermo,
Italia; Phone: +393276988282; Mail:
[email protected]
References
1. de Miguel Criado et al; MR Imaging Evaluation of Perianal Fistulas: Spectrum of Imaging Features; RadioGraphics 2012; 32:175–194;
2. O’Malley RB,
Al-Hawary MM,
Kaza RK,
Wasnik AP,
Liu PS,
et al.
(2012) Rectal imaging: part 2,
Perianal fistula evaluation on pelvic MRI--what the radiologist needs to know.
AJR Am J Roentgenol 199: W43-53.
3. Baskan O.
et al.; Our experience with MR imaging of perianal fistulas; Pol J Radiol,
2014; 79: 490-497;
4. Parks AG,
Gordon PH,
Hardcastle JD.
A classificatioN of fistula-in-ano.
Br...