Magnetic resonance imaging of anal fistulae

doi:10.1016/0140-6736(92)91472-K

The Lancet

Volume 340, Issue 8816, 15 August 1992, Pages 394-396

https://doi.org/10.1016/0140-6736(92)91472-K Get rights and content

Abstract

Success of surgery for an anal fistula depends on accurate assessment of the fistula; however, such assessment is technically difficult. We have done a prospective study that determined the accuracy of magnetic resonance imaging (MRI) in demonstrating the course of fistulae, by comparing MRI scan interpretations with subsequent operative findings. 16 patients (mean [range] age 42 [24-66] years) had MRI followed by surgery within a mean of 22 (1-101) days. MRI scan interpretations agreed precisely with independently documented operative findings in 14 of 16 patients. MRI is an accurate method of delineating anal fistulae, and should be considered for patients with difficult fistulae that recur despite skilled attention because it demonstrates abnormalities that might otherwise be missed.

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Evaluating postoperative anal fistula prognosis by diffusion-weighted MRI
2020, European Journal of Radiology
The purpose of this study was to explore whether preoperative diffusion-weighted magnetic resonance imaging (DW-MRI) can be used to evaluate the prognosis of anal fistula and identify the influence factors of postoperative recurrence.
This is a retrospective study of 117 patients with anal fistula who have undergone preoperative DW-MRI and surgery. All patients were followed up by telephone or reexamination within 2 years after surgery. Of the 117 patients, 35 were excluded due to loss of follow-up and only 82 were included in this study. MRI fistula imaging-related data were analyzed, and fistula severity was scored using criteria of both local extension of fistulas and active inflammation for a total maximum score of 22. The apparent diffusion coefficient (ADC) value of the fistula in patients with anal fistula during preoperative MRI examination was measured. According to whether anal fistula patients are accompanied by perianal abscess, they are divided into two groups, namely anal fistula group and anal fistula with abscess group. Based on whether patients with anal fistula recur after surgery, they were further divided into recurrent group and non-recurrent group.
82 patients with anal fistula were included in this analysis, 23 of them recurred and 59 were cured. Among patients with perianal abscess, the mean ADC value of the recurrent group was (1.19 ± 0.21)×10⁻³ mm²/s, which is significantly lower than that of the non-recurrent group (1.36 ± 0.19)×10⁻³ mm²/s. There were significant statistical differences in ADC values between the two groups (p = 0.03). Among patients with anal fistulas without abscesses, 15 patients recurred after surgery, with a mean ADC value of (1.45 ± 0.27) ×10^-3 mm²/s, and 33 patients didn’t occur, with a mean ADC value of (1.44 ± 0.31)×10⁻³ mm²/s. The ADC value of preoperative fistula in patients was negative significant correlation with MRI findings score (r= -0.332, P = 0.002). Risk factors for the recurrence after anal fistula surgery include the time interval between MRI and operation, multiple fistula tracks. Fatigue, excessive intake of spicy or greasy food and diarrhea may also be external risk factors for postoperative recurrence of patients with anal fistula.
DW-MRI has important application value for the prognosis evaluation of anal fistula. Complex type of anal fistula and improper lifestyle are the main risk factors affecting the recurrence after anal fistula surgery.
Magnetic Resonance Imaging of Fistula-In-Ano
2020, Magnetic Resonance Imaging Clinics of North America
Citation Excerpt :
Furthermore, of the 16 patients who needed further unplanned surgery, MR imaging correctly predicted the site of recurrent disease in all cases.11 Ever since Lunnis’ work suggested that EUA might not be as accurate as MR imaging,14 comparative studies have been plagued by the lack of a genuine reference standard. It is now well-recognized that surgical findings at EUA are often incorrect.
Value of diffusion weighted MRI in assessment of simple and complicated perianal fistula
2017, Egyptian Journal of Radiology and Nuclear Medicine
The aim of this study was to explore the role of the DWI in assessment of peri-anal fistula and whether it can replace post contrast study.
MRI examinations was done for 35 patients. Images were reviewed for the presence and number of visible fistulas, internal openings, secondary extension, horse shoe and abscess. Apparent diffusion coefficient (ADC) measurement of suspected fistula tracks and abscess cavities was done to assess activity. Comparison between TIRM, DWI and post-contrast T1-weighted fat saturated sequences was done. Surgical findings were the reference standard.
Contrast enhanced images were superior to DWI in detection of primary fistula and internal opening while they were equivalent in detection of secondary extensions and abscess. There was no significant difference in overall accuracy of detection of perianal fistula and its complications between combined (DWI and TIRM images) and post contrast images. There was significant difference between ADC values of active and inactive fistulae and between abscess and inflammatory reaction.
Combined DWI and TIRM is equivalent to post contrast images in detection of primary and complicated fistula. DWI is useful in differentiation between abscess and inflammatory reaction, and assessment of disease activity.
Added value of diffusion-weighted magnetic resonance imaging for the diagnosis of perianal fistula
2017, Diagnostic and Interventional Imaging
To evaluate the added value of diffusion-weighted (DWI) magnetic resonance imaging (MRI) by comparison with T2-weighted images alone in the diagnosis of perianal fistula.
MRI examinations of 123 patients (97 men, 26 women; mean age, 41.9 years) with suspected perianal fistula were retrospectively evaluated by two radiologists. Fat-suppressed T2-weighted fast spin echo images, DWI (b values, 0 and 1000 s/mm²) and fat-suppressed gadolinium chelate-enhanced T1-weighted images were evaluated for each patient by using a four-point scale. Confidence scores and sensitivities were calculated for T2-weighted images alone, the combination of DWI and T2-weighted images and the combination of gadolinium chelate-enhanced T1-weighted images and T2-weighted images. The combination of gadolinium chelate-enhanced and T2-weighted images was used as reference standard.
Perianal fistulas were present in 92/123 patients (74.8%). An almost perfect interobserver agreement was found for T2-weighted images (kappa = 0.868), the combination of gadolinium chelate-enhanced T1-weighted images and T2-weighted images (kappa = 0.96) and the combination of DWI and T2-weighted images (kappa = 0.90). The confidence scores for the diagnosis of perianal fistula for the combination of gadolinium chelate-enhanced T1-weighted images and T2-weighted images were greater than those of T2-weighted images alone for observer 1 (P < 0.001) and observer 2 (P = 0.009). The confidence scores of the combination of DWI and T2-weighted images were greater than those of T2-weighted images alone for observer 1 (P < 0.001) and observer 2 (P = 0.032). Sensitivity and specificity of the combination of DWI and T2-weighted images were greater than those of T2-weighted images alone for both observers.
DWI has a significant added value compared to T2-weighted imaging alone in the diagnosis of perianal fistula.
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2017, Current Problems in Surgery

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SHORT REPORTSMagnetic resonance imaging of anal fistulae

Abstract

Fistula-m-ano in a defined population. Incidence and epidemiological aspects

Acta Chir Gynaecol

Fistula-in-ano is usually simple to manage surgically

Int J Colorectal Dis

Insights gained from the management of problematical anal fistulae at St Mark's Hospital, 1984-88

Br J Surg

Fistulography for fistula-in-ano

Dis Colon Rectum

SHORT REPORTS
Magnetic resonance imaging of anal fistulae