Clinical and MR imaging features of cryptoglandular and Crohn's fistulas and abscesses

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

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.

Perianal sepsis: surgical perspective and practical MRI reporting for radiologists

This article describes the development of a structured MRI reporting template and diagrammatic worksheet for perianal sepsis through collaboration between radiologists and colorectal surgeons at our institution, and the rationale behind each component of the worksheet. Benefits of this reporting worksheet include optimizing communication of key imaging findings that have a real impact on patient management, less time spent on reporting the study, and easier comparison between studies. We illustrate the utility of the report template with case studies. We summarize the current surgical approaches to perianal sepsis to help radiologists focus on reporting the findings relevant to surgical planning.

Features and perspectives of MR enterography for pediatric Crohn disease assessment

The aim of this paper is to provide indications for performing magnetic resonance enterography (MRE) in Crohn's disease (CD), the essential technical elements of MRE techniques and typical findings in patients with CD. Patients suffering from CD frequently require cross-sectional imaging. By performing MRE, it is possible to obtain results comparable to those obtained with endoscopy in terms of identifying and assessing disease activity and better than other cross-sectional imaging techniques, such as CT, in the evaluation of the fibrosis and complications of disease. The MR imaging of diffusion MR is a technique which enables medical staff to add important additional information and which may replace the use of intravenous contrast agents in the near future. Magnetic resonance enterography is an accurate tool for assessing bowel disease and the various complications associated with CD. The lack of exposure to non-ionizing radiation is an important advantage of this imaging technique, especially in the case of pediatric patients. Familiarity with common and pathognomonic imaging features of CD is essential for every clinician involved in the treatment of inflammatory bowel disease and the care of patients.

Perianal disease in pediatric Crohn disease: a review of MRI findings

Perianal complications of Crohn disease are a common occurrence in children and can result in significant morbidity when not accurately characterized prior to surgical intervention. MRI is an excellent imaging modality for the evaluation of perianal inflammatory bowel disease - allowing characterization and detailed description of perianal fistulas. MRI has many advantages over other imaging modalities for the pediatric patient. Radiologists will benefit from a sophisticated understanding of perianal anatomy, the classification of perianal fistulas, the advantages MRI offers in characterization of perianal fistulas as well as the common and incidental findings that are important in the MRI evaluation of perianal inflammatory bowel disease in children. Perianal fistulas are found at a high rate in pediatric referrals and are more commonly found in male patients.

Chronic anal and perianal pain resolved with MRI

OBJECTIVE

The purpose of this study was to assess the diagnostic value of anorectal MRI in the care of patients with chronic anal and perianal pain but without findings of abnormalities in the clinical workup.

MATERIALS AND METHODS

Patients referred from a tertiary department of colorectal surgery to the MRI unit with clinically occult chronic anal and perianal pain were included. MRI of the anorectum was performed with an endoanal or pelvic phased-array coil. The images from all examinations were read by two radiologists. MRI findings were correlated with clinical follow-up data.

RESULTS

The study group (103 patients) was stratified into patients with no history of anorectal disease (n = 60) and those who had a history of surgery for anorectal disease (n = 43). MRI findings suggested the final diagnoses in 40 patients (39%). These diagnoses were 28 cases of suppurative lesions (27%), 11 cases of painful scarring of the anus (11%), and one case of metastasis to the sacrum (1%). Suppurative lesions were surgically proved with marked relief of pain after surgery. In the other patients the final diagnoses were 37 cases of levator ani syndrome (36%) and 26 cases of unspecified functional anorectal pain (25%). No MRI abnormalities were found in 33 of the patients with levator ani syndrome and 26 of the patients with unspecified anorectal pain. The two readers had very good agreement (κ = 0.92). The patients with a history of anorectal disease had significantly more MRI findings of abnormalities (60%) than did patients without a history of anorectal disease (23%). The positive predictive value of MRI was 91%, and the negative predictive value was 100%.

CONCLUSION

In 39% of patients, MRI showed abnormalities that were clinically confirmed as the final diagnosis. Surgical treatment will especially benefit patients with suppurative lesions, resulting in relief of pain.

MR imaging evaluation of perianal fistulas: spectrum of imaging features

Perianal fistulization is an inflammatory condition that affects the region around the anal canal, causing significant morbidity and often requiring repeated surgical treatments due to its high tendency to recur. To adopt the best surgical strategy and avoid recurrences, it is necessary to obtain precise radiologic information about the location of the fistulous track and the affected pelvic structures. Until recently, imaging techniques played a limited role in evaluation of perianal fistulas. However, magnetic resonance (MR) imaging now provides more precise information on the anatomy of the anal canal, the anal sphincter complex, and the relationships of the fistula to the pelvic floor structures and the plane of the levator ani muscle. MR imaging allows precise definition of the fistulous track and identification of secondary fistulas or abscesses. It provides accurate information for appropriate surgical treatment, decreasing the incidence of recurrence and allowing side effects such as fecal incontinence to be avoided. Radiologists should be familiar with the anatomic and pathologic findings of perianal fistulas and classify them using the St James's University Hospital MR imaging-based grading system.

A diagnostic accuracy meta-analysis of endoanal ultrasound and MRI for perianal fistula assessment

BACKGROUND

Imaging modalities such as endoanal ultrasound or MRI can be useful preoperative adjuncts before the appropriate surgical intervention for perianal fistulas.

OBJECTIVES

We present a systematic review of published literature comparing endoanal ultrasound with MRI for the assessment of idiopathic and Crohn's perianal fistulas.

DESIGN

A meta-analysis was performed to obtain pooled values for specificity and sensitivity.

SETTINGS

Electronic databases were searched from January 1970 to October 2010 for published studies.

PATIENTS AND INTERVENTIONS

Four studies were used in our analysis. There were 241 fistulas in the ultrasound group and 240 in the magnetic resonance group.

RESULTS

The combined sensitivity and specificity of magnetic resonance for fistula detection were 0.87 (95% CI: 0.63-0.96) and 0.69 (95% CI: 0.51-0.82). There was a high degree of heterogeneity between studies reporting on MRI sensitivity (df = 3, I = 93%). This compares to a sensitivity and specificity for endoanal ultrasound of 0.87 (95% CI: 0.70-0.95) and 0.43 (95% CI: 0.21-0.69). There was a high degree of heterogeneity between studies reporting on endoanal ultrasound sensitivity (df = 3, I = 92%).

CONCLUSIONS

From the available literature, the summarized performance characteristics for MRI and endoanal ultrasound demonstrate comparable sensitivities at detecting perianal fistulas, although the specificity for MRI was higher than that for endoanal ultrasound. Both specificity values are considered to be diagnostically poor, however. The high degree of data heterogeneity and the shortage of applicable studies precludes any firm conclusions being made for clinical practice. Future trials with improved study design (including prospective data collection and consideration of verification bias) may help to further clarify the role of MRI in the assessment and treatment response monitoring of perianal fistulas (particularly in patients with Crohn's disease).

Evaluation of an MRI-based score of disease activity in perianal fistulizing Crohn's disease

To evaluate a magnetic resonance imaging (MRI)-based score of disease severity for perianal fistulizing Crohn's disease (CD), 16 patients with perianal fistulizing CD underwent 1.5-T MRI before and after infliximab therapy. MRI scores, Perianal Disease Activity Index (PDAI) and C-reactive protein (CRP) were calculated, and fistula drainage was assessed. These items were compared for responders and nonresponders. After therapy, PDAI values and CRP values decreased significantly in responders, but there were no significant differences in the MRI scores. In all responders, MRI findings were indicative of persisting active inflammation. In these patients, a relapse rate of 57% was seen.

Emerging treatments for complex perianal fistula in Crohn’s disease

Complex perianal fistulas have a negative impact on the quality of life of sufferers and should be treated. Correct diagnosis, characterization and classification of the fistulas are essential to optimize treatment. Nevertheless, in the case of patients whose fistulas are associated with Crohn’s disease, complete closure is particularly difficult to achieve. Systemic medical treatments (antibiotics, thiopurines and other immunomodulatory agents, and, more recently, anti-tumor necrosis factor-α agents such as infliximab) have been tried with varying degrees of success. Combined medical (including infliximab) and less aggressive surgical therapy (drainage and seton placement) offer the best outcomes in complex Crohn’s fistulas while more aggressive surgical procedures such as fistulotomy or fistulectomy may increase the risk of incontinence. This review will focus on emerging novel treatments for perianal disease in Crohn’s patients. These include locally applied infliximab or tacrolimus, fistula plugs, instillation of fibrin glue and the use of adult expanded adipose-derived stem cell injection. More well-designed controlled studies are required to confirm the effectiveness of these emerging treatments.

MR colonography without bowel purgation for the assessment of inflammatory bowel diseases: diagnostic accuracy and patient acceptance

BACKGROUND

The purpose of this pilot study was to assess the diagnostic accuracy of MR colonography (MRC) without bowel cleansing regarding its ability to quantify inflammatory bowel disease (IBD). In addition, patient acceptance was compared with conventional colonoscopy (CC).

METHODS

In all, 29 patients with IBD (17 ulcerative colitis; 12 Crohn's disease) were included. While CC was performed after bowel cleansing as the gold standard, MRC was based on a fecal tagging technique and performed 48-72 hours prior to CC. The presence of inflammation in each of 7 ileocolonic segments was rated for every procedure. Patients evaluated both modalities and dedicated aspects of the examination according to a 10-point-scale (1 = good, 10 = poor acceptance). Furthermore, preferences for future examinations were investigated.

RESULTS

Inflammatory segments were found by means of CC in 23 and by MRC in 14 patients. Overall sensitivity and specificity of MRC in a segment-based detection were 32% and 88%, respectively. Concerning severely inflamed segments, sensitivity increased to 53% for MRC. Overall acceptance of CC was significantly higher compared to MRC (mean value (mv) for MRT = 6.0; CC = 4.1; P = 0.003). For MRC, the placement of the rectal tube (mv = 7.3), and for CC bowel purgation (mv = 6.5), were rated as the most unpleasant. A total of 67% of patients voted for CC as the favorable tool for future examinations.

CONCLUSIONS

The presented data indicate that 'fecal tagging MRC' is not suitable for an adequate quantification of inflammatory diseases of the large bowel. Furthermore, overall acceptance of endoscopic colonoscopy was superior to MRC.

Magnetic resonance fistulography for the demonstration of anovaginal fistula: an alternative imaging technique?

Anovaginal fistulae (AVF) are frequently seen in patients with inflammatory bowel disease, especially in Crohn disease with active colonic inflammation. Herein, we report a 21-year-old woman with Crohn disease suffering from vaginal discharge and anal pain. Although clinical presentation was very suggestive of AVF, physical examination and colonoscopy were inconclusive. We used an alternative technique and performed magnetic resonance fistulography by applying rectal contrast for the demonstration of AVF.

Magnetic resonance imaging of perianal fistulas

Most cases of fistula-in-ano are nonspecific and result from inflammation of anal glands and crypts (cryptoglandular). The classification of cryptoglandular fistulas depends on the degree of involvement of the anal sphincter complex and determines the type of treatment. Studies have shown that preoperative MR imaging revealed important additional information compared with surgery alone and better predicts clinical outcome of patients with fistula-in-ano than initial surgical exploration. With the emergence of novel surgical treatments like MRI-guided surgery, laser, and adhesive treatments, MR imaging is a mainstay for preprocedural and intraoperative evaluation to ensure the adequacy of the procedure.

Differentiation of perianal fistulas with digital subtraction magnetic resonance fistulography

BACKGROUND

Pelvic magnetic resonance imaging (MRI) is accurate in identifying perianal fistulas. The exact visualization of fistulous tracts and concomitant abscesses determine the type of treatment. To improve the detection of perianal fistulas, we studied digital subtraction MR-fistulography for tissue differentiation based on signal intensity measurements.

METHODS

This study included 75 patients with the clinical diagnosis of perianal fistula. All patients were analyzed by a thin-slice, high-resolution, fast low-angle shot 3-dimensional sequence in the axial plane before and after intravenous injection of gadobenate dimeglumine, followed by image subtraction. Operator-defined regions of interest were used to calculate signal intensities of the inflamed fibrous walls of fistulas, the common femoral artery, the internal and external sphincter muscles, and the gluteus muscle. The fistulas were classified according to Parks classification.

RESULTS

Based on signal intensity measurements in 75 patients with perianal fistulas, diagnosed by digital subtraction MR-fistulography, a significant differentiation between fistulous tracts and anatomic structures was possible. MRI identified 116 perianal fistulas (34 intersphincteric, 33 transsphincteric, 10 suprasphincteric, and 39 extrasphincteric) and 35 abscesses.

CONCLUSIONS

Digital subtraction MR-fistulography is a new, promising, noninvasive imaging technique for the detection of perianal fistulas and abscesses.

Assessment of anal fistulas with high-resolution subtraction MR-fistulography: comparison with surgical findings

PURPOSE

To investigate a new MR-imaging protocol defined as subtraction MR-fistulography for the detection of fistula-in-ano.

MATERIALS AND METHODS

A total of 36 patients (18 men, 18 women) with the clinical diagnosis of anal fistula or abscess who were scheduled for surgical exploration were preoperatively imaged at 1.5 T in the supine position; coronal STIR sequences and axial T1-weighted three-dimensional FLASH sequences before and after intravenous injection of gadobenate dimeglumine (Gd-BOPTA) were obtained. Image subtraction was routinely used. The image findings were compared with the findings at surgical exploration according to a uniform classification system.

RESULTS

A total of 46 fistulas were seen on subtraction MR-fistulography, whereas surgery described 41 fistulas. MRI and surgery concordantly depicted a total number of 40 fistulas, six fistulas were only described by MRI, and one fistula was only seen during surgery. A total of 27 abscesses were detected with MRI, compared to 22 during surgery. A total of 22 abscesses were concordantly diagnosed. Complete agreement between subtraction MR-fistulography and surgery occurred in 32 (89%) of the 36 patients. The four patients in whom both procedures disagreed had complex anal sepsis with multiple fistulas and/or abscesses due to Crohn disease.

CONCLUSION

High-resolution subtraction MR-fistulography is an important complement to surgical exploration and especially suitable for investigating complex anal sepsis.