Getting the most out of MRI in perianal fistula: update on surgical techniques and radiological features that define surgical options

Iqbal, Nusrat; Tozer, P; Fletcher, Jordan; Lightner, Amy L.; Sackitey, Charlene; Corr, Alison; Patel, Uday; Ilangovan, Rajapandian; Lung, Phillip F. C.

doi:10.1016/j.crad.2021.06.018

Cited by 14 publications

(18 citation statements)

References 27 publications

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“…3 A fistula tract running obliquely cephalad from the internal opening will result in division of a greater proportion of musculature with fistulotomy. Reproduced with permission [4] Fig. 4 Tight or successive angulation of branches can be challenging to probe for seton insertion and to negotiate with a rigid VAAFT scope agreed the fundamental characteristics influencing management decisions, universal to all patients regardless of aetiology, clinical history and scope of practice the treating centre.…”

Section: Discussionmentioning

confidence: 99%

“…Ethical committee approval was not required. The recommended MR sequences and protocols required for assessment of relevant features is beyond the scope of this project, and has been described in detail elsewhere [1,4,[6][7][8].…”

Section: Systematic Review and Clinician Surveymentioning

confidence: 99%

“…Internal opening diameter Measurement of the internal opening is frequently inaccurate as the canal is collapsed and the internal opening components (sphincter defect, epithelial/ granulation tissue) vary. Despite this, the importance of internal opening diameter in surgical decision-making was highlighted, particularly in specific surgical procedures (Table 3) [4]. The panel agreed that a large internal opening was deemed to be remarkable and relevant to clinical practice and therefore should be reported (Figure 2); however, due to the difficulties in taking accurate measurements, quantification of size was not considered helpful.…”

Section: Internal Openingmentioning

confidence: 99%

“…This is a challenge, as anal fistulae can be complex and reporting requires precise description of the spatial configuration of key features. Both free-text and structured reporting [3][4][5] have advantages and disadvantages, whilst a minimum dataset, set of features that should be reported for all anal fistulae, can be used in either style emphasising items that are most valuable.…”

Section: Introductionmentioning

confidence: 99%

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The development of a minimum dataset for MRI reporting of anorectal fistula: a multi-disciplinary, expert consensus process

et al. 2022

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There are a range of sphincter-preserving procedures available to treat anorectal fistula, some of which can be precluded, or rendered more optimal by specific features of fistula anatomy. Magnetic resonance imaging (MRI) is the gold standard modality for assessing anorectal fistula. To maximise clinical utility, the MRI report should accurately describe these clinically relevant features. We aimed to develop a minimum dataset for reporting MRI of anorectal fistula, in order to improve the assessment and management of these patients. A longlist of 70 potential items for the minimum dataset was generated through systematic review of the literature. This longlist was presented to radiologists, surgeons and gastroenterologists in an online survey to understand the features that shape current clinical practice. The longlist and survey results were then presented to an expert consensus panel to generate the final minimum dataset through discussion and anonymous voting. The final minimum dataset details the general characteristics, features of the internal and external openings, path of the fistula through the sphincters and any associated extensions and collections that should be described in all MRI reports for anal fistula. Additional surgical and perianal Crohn’s disease subsets were developed to indicate the features that aid decision-making for these patients, in addition to a minimum dataset for the clinical request. This study represents a multi-disciplinary approach to developing a minimum dataset for MRI reporting of anal fistula, highlighting the most important features to report that can assist in clinical decision-making. Key Points • This paper recommends the minimum features that should be included in all MRI reports for the assessment of anal fistula, including Parks classification, number of tracts, features of the internal and external opening, path of the tract through the sphincters, the presence and features of extensions and collections. • Additional features that aid decision-making for surgery or in the presence of Crohn’s disease have been identified. • The items that should be included when requesting an MRI are specified.

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Section: Discussionmentioning

confidence: 99%

Section: Systematic Review and Clinician Surveymentioning

confidence: 99%

Section: Internal Openingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The development of a minimum dataset for MRI reporting of anorectal fistula: a multi-disciplinary, expert consensus process

et al. 2022

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“…Previous studies have shown that the internal opening of the transsphincteric anal fistula was located above the dentate line, and the angle between the running direction of the fistula and the longitudinal axis of the anal canal was 35° (range 14–91°) [ 15 ], but it was difficult to completely remove the internal opening and fistula from this angle during surgery, which increases the recurrence rate after surgery. Therefore, preoperative MRI may provide the surgeon with more important information [ 16 ]. Clinical classification of hemorrhoids is mainly based on the anatomical mark of the anal canal dentate line.…”

Section: Discussionmentioning

confidence: 99%

Accuracy of magnetic resonance imaging in defining dentate line in anal fistula

et al. 2022

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Purpose To retrospectively assess the accuracy of magnetic resonance imaging (MRI) in defining dentate line in anal fistula. Materials and methods Seventy patients with anal fistulas were assessed by dynamic contrast-enhanced MRI. The distance from the dentate line to the anal verge for all patients was measured by MRI. To mitigate interference, 35 patients with anal fistulas whose internal openings were located on the dentate line were excluded from this study. Two observers independently judged the positional relationship between the internal opening and the MRI-defined dentate line, and compared with the results observed by surgeon to assess the accuracy. Results The distance between the MRI-defined dentate line and the anal verge depended on the location of the internal opening and the morphology of the anal canal mucosa. The distance based on the location the internal opening and the morphology of the anal canal mucosa was 18.2 ± 8.1 mm and 20.0 ± 5.3 mm on oblique coronal T2WI, respectively. Compared with the results observed by the surgeon, the accuracy of evaluating the positional relationship between the internal opening and the dentate line from the morphology of the anal canal mucosa on MRI exceeded 89.9%. Taking 18.2–20.0 mm as the distance between the dentate line and the anal verge on the MRI image, the accuracy of evaluating the relationship between the position of the internal opening and the dentate line was over 85.7%. Considering both the dentate line and the anal canal mucosa, the accuracy of evaluating the relationship between the internal opening and the dentate line was over 91.5%. The results of MRI-defined dentate line were in good agreement with the results of intraoperative surgeon evaluation, and the κ values were 0.70, 0.63, and 0.78, respectively. Conclusion MRI has high accuracy in defining the dentate line in anal fistulas.

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Comparison of MRI and Endoanal Ultrasound in Assessing Intersphincteric, Transsphincteric, and Suprasphincteric Perianal Fistula

Akhoundi

Bozchelouei

Abrishami

et al. 2023

J of Ultrasound Medicine

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ObjectivesPerianal fistula is a common disorder characterized by an anomalous perianal track connecting two epithelialized surfaces, most commonly the anal canal and the perianal skin. Although each has its limitations, magnetic resonance imaging (MRI) and endoanal ultrasound are currently two acceptable modalities for assessing perianal fistula. This study aimed to evaluate the accuracy of MRI and endoanal ultrasonography in diagosing perianal fistula, considering the surgical results as the references.MethodsThis prospective cohort study was performed on patients with symptomatic perianal fistulas. MRI results of patients reported by the radiologist were collected along with the findings of endoanal ultrasonography performed by a gastroenterologist. These results were compared with surgical findings as the reference standard.ResultsThe study enrolled 126 patients. Exactly 222 definitive fistulas were identified during surgery. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of ultrasound for perianal fistula were 87.38, 38.46, 92.38, 26.31, and 82.25% respectively; and for MRI were 76.12, 57.69, 93.88, 22.05, and 74.19% respectively. The accuracy of endoanal ultrasound for detecting transsphincteric and intersphincteric fistulas was higher than MRI. In contrast, the diagnostic value of MRI for detecting suprasphincteric fistulas was higher than endoanal ultrasound.ConclusionsUsing endoanal ultrasonography to diagnose perianal fistulas is a relatively accurate method. This method may be more sensitive than MRI in detecting patients with perianal fistulas and abscesses.

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Getting the most out of MRI in perianal fistula: update on surgical techniques and radiological features that define surgical options

Cited by 14 publications

References 27 publications

The development of a minimum dataset for MRI reporting of anorectal fistula: a multi-disciplinary, expert consensus process

The development of a minimum dataset for MRI reporting of anorectal fistula: a multi-disciplinary, expert consensus process

Accuracy of magnetic resonance imaging in defining dentate line in anal fistula

Comparison of MRI and Endoanal Ultrasound in Assessing Intersphincteric, Transsphincteric, and Suprasphincteric Perianal Fistula

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