MRI for assessment of anal fistula

The role of MRI in perianal fistulizing disease: diagnostic imaging and classification systems to monitor disease activity

Perianal fistulizing disease, commonly associated with Crohn's disease, poses significant diagnostic and therapeutic challenges due to its complex anatomy and high recurrence rates. Radiological imaging plays a pivotal role in the accurate diagnosis, classification, and management of this condition. This article reviews the current radiological modalities employed in the evaluation of perianal fistulizing disease, including magnetic resonance imaging (MRI), endoanal ultrasound, and computed tomography (CT). MRI, recognized as the gold standard, offers superior soft tissue contrast and multiplanar capabilities, facilitating detailed assessment of fistula tracts and associated abscesses. CT, although less detailed than MRI, remains valuable in acute settings for detecting abscesses and guiding drainage procedures. This article discusses the advantages and limitations of each modality, highlights the importance of standardized imaging protocols, and underscores the need for interdisciplinary collaboration in the management of perianal fistulizing disease. Future directions include advancements in imaging techniques and the integration of artificial intelligence to enhance diagnostic accuracy and treatment outcomes.

Cellular angiofibroma arising from the rectocutaneous fistula in an adult: A case report

BACKGROUND

Rectocutaneous fistulae are common. The infection originates within the anal glands and subsequently extends into adjacent regions, ultimately resulting in fistula development. Cellular angiofibroma (CAF), also known as an angiomyofibroblastoma-like tumor, is a rare benign soft tissue neoplasm predominantly observed in the scrotum, perineum, and inguinal area in males and in the vulva in females. We describe the first documented case CAF that developed within a rectocutaneous fistula and manifested as a perineal mass.

CASE SUMMARY

In the outpatient setting, a 52-year-old male patient presented with a 2-year history of a growing perineal mass, accompanied by throbbing pain and minor scrotal abrasion. Physical examination revealed a soft, well-defined, non-tender mass at the left buttock that extended towards the perineum, without a visible opening. The initial assessment identified a soft tissue tumor, and the laboratory data were within normal ranges. Abdominal and pelvic computed tomography (CT) revealed swelling of the abscess cavity that was linked to a rectal cutaneous fistula, with a track-like lesion measuring 6 cm × 0.7 cm in the left perineal region and attached to the left rectum. Rectoscope examination found no significant inner orifices. A left medial gluteal incision revealed a thick-walled mass, which was excised along with the extending tract, and curettage was performed. Histopathological examination confirmed CAF diagnosis. The patient achieved total resolution during follow-up assessments and did not require additional hospitalization.

CONCLUSION

CT imaging supports perineal lesion diagnosis and management. Perineal angiofibromas, even with a cutaneous fistula, can be excised transperineally.

Contemporary management of anorectal fistula

Anorectal fistula is a common, chronic condition, and is primarily managed surgically. Herein, we provide a contemporary review of the relevant etiology and anatomy anorectal fistula, treatment recommendations that summarize relevant outcomes and alternative considerations, in particular when to refer to a fistula expert.

Clinical approach to patients with an ileal pouch

Restorative proctocolectomy with ileal pouch-anal anastomosis is the procedure of choice to maintain intestinal continuity when a total proctocolectomy is a required. It is a technically challenging operation that may be burdened by several nuanced complications both in the immediate postoperative period and in the long term. Most patients with a pouch and any kind of complication will undergo radiological studies, thus multidisciplinary collaboration between surgeons, gastroenterologists, and radiologists is paramount to their timely and accurate diagnosis. When treating pouch patients, radiologists should be familiar with regular pouch anatomy and its appearance in imaging studies, as well as with the most common complications that can occur in this population. In this review, we examine the clinical decision-making process at each step before and after pouch creation, as well as the most common complications associated with pouch surgery, their diagnosis, and their management.

Preoperative magnetic resonance imaging of anal fistulas with scrotal extension: a retrospective study

Introduction

This study aimed to elucidate the magnetic resonance (MR) characteristics of anal fistulas extending to the scrotum, and the applicable rules, and to correlate MR features with surgical findings.

Methods

We conducted a retrospective study in 150 consecutive patients with anal fistulas extending into the scrotum, who were diagnosed and underwent surgery at University Medical Center Ho Chi Minh City between January 2017 and April 2022. MR findings were evaluated and compared with surgical findings using Cohens kappa coefficient (k) with a 95% confidence interval.

Results

150 patients (mean age 37.6 ± 10.9 years) with 166 fistulas, including 150 anal fistulas with scrotal extension. Most fistulas were low transsphincteric (80.0%, 120/150 patients). There was a strong agreement for primary tract classification and detecting the location of internal openings between MRI and surgical findings with k = 0.83 (0.780.87) and k = 0.89 (0.85 0.93) (p<0.001), respectively. There is a significant correlation between the location of internal openings and the type of fistula (p<0.05). Low transsphincteric fistulas were predominant in the anterior group (103/122 patients vs. 10/19 patients), while in the posterior group, it was more common in the high transsphincteric fistulas (7/19 patients vs. 14/122 patients), and the intersphincteric fistulas (1/19 patients vs. 5/122 patients); and the suprasphincteric fistulas were only seen in the posterior group (1 patient).

Conclusion

Anal fistulas with scrotal extension are exceptions to Goodsalls rule. Albeit long-tract fistulas, most are low transsphincteric and have anterior internal openings.

Evaluation of the Effectiveness of a Combination of Chinese Herbal Fumigation Sitz-Bath and Red Ointment in Managing Postoperative Wound Healing and Pain Control in Anal Fistula Patients

Objective

To explore the efficacy of Chinese herbal fumigation and sitz-bath combined with red ointment in the treatment of postoperative wound healing and pain control in anal fistula patients.

Methods

A total of 118 anal fistula patients were selected as the study population, randomly divided into two groups, i.e., the research group (n = 60) and the control group (n = 60). The control group was treated with red ointment therapy for postoperative wound healing and pain while the research group was treated with a combination of ointment and traditional Chinese medicine fumigation sitz-bath, Postoperative wound healing, pain control, and safety evaluation were compared between the two groups. Results. The total effective rate in the research group was 96.67%, which was significantly higher than that in the control group (93.10%), and the difference was statistically significant (P < 0.05). The VAS scores and postoperative wound healing times in the research group were significantly lower than those in the control group. The difference was statistically significant (P < 0.05). A day after postoperative treatment, there was no significant difference (P > 0.05) in TNF-α and IL-6 levels between the two study groups; however, from day 3 to day 14 the levels were statistically different. TNF-α and IL-6 levels in research group were significantly lower than those in the control group. The difference was statistically significant (P < 0.05). The incidence of postoperative complications in the research group at 6.67% was statistically significant (P < 0.05), significantly lower than 13.79% in the control group. Conclusion. Postoperative intervention with Chinese herbal fumigation and sitz-bath combined with red ointment can effectively reduce the wound healing duration and lower the degree of pain experienced by anal fistula patients, thereby improving their quality of life.

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 fistulas: A review with emphasis on preoperative imaging

PURPOSE

We aim to present a comprehensive literature review which focuses on the preoperative imaging of perianal fistulas.

MATERIAL/METHODS

Pelvic magnetic resonance imaging (MRI) and endoanal ultrasound (EAUS) are the two first-line imaging modalities for the preoperative evaluation of patients with perianal fistulas. We conducted a search in PubMed, Scopus and Google Scholar concerning articles comparing pelvic MRI with EAUS, which were published from 1994 until 2019.

RESULTS

In most articles, pelvic MRI is superior to EAUS for the evaluation of perianal fistulas (especially for supralevator and extrasphincteric ones). Preoperative pelvic MRI is associated with statistically significant better results and prognosis after surgical treatment of the disease. Preoperative EAUS poses high sensitivity and specificity in identifying intersphincteric and transsphincteric perianal fistulas, as well as the internal opening of a fistula-in-ano. There is only one meta-analysis which compares the diagnostic accuracy of the two mentioned imaging modalities in preoperative fistula detection. Sensitivity of both - pelvic MRI and EAUS, is acceptably high (0.87). Specificity of pelvic MRI is 0.69 in comparison to EAUS (0.43), but both values are considered low.

CONCLUSIONS

Future well-designed prospective studies are needed to investigate the diagnostic accuracy of pelvic MRI and EAUS in the preoperative assessment of patients with perianal fistulas. Moreover, the combination of pelvic MRI and EAUS should also be studied, since several published articles suggest that it could lead to improved diagnostic accuracy. A novel treatment algorithm for perianal fistulas could arise from this study.

Congenital Cheek Fistula: A Rare Case of Developmental Abnormality in the Buccal Area

A congenital cheek fistula is a rare malformation in the buccal area. Here, we report the case of a congenital cheek fistula in a 50-year-old woman who visited our clinic with complaints of swelling and pain in her left cheek. Physical examination revealed a small hole in the left corner of the mouth present since birth. She had no other congenital malformations in the maxillofacial region such as an accessory ear and cleft lip. Manual compression of the cheek mass induced serous discharge from the hole. Magnetic resonance imaging (MRI) showed a cystic lesion in the left cheek and a fistula within the orbicularis oris muscle that opened into the small hole. After immediate incision and drainage of the cyst, both the cyst and fistula were surgically resected. The cystic lesion was completely delineated from the boundary of the parotid gland. The orbicularis oris muscle was partially incised to remove the fistula and the surrounding scar tissue. Histopathological examination of the resected specimen revealed a cavity consisting of epithelium inside the fistula. The postoperative course was insignificant. No recurrence of the cyst was observed six months postoperatively. The operative and pathological findings demonstrated that the ectoderm-derived epithelial tissue was enclosed by the mesoderm-derived muscle tissue. The mixture of different germ layer-derived tissues suggested that the fistula was a type of congenital transverse facial cleft induced by malfusion of the mandibular and maxillary prominences during embryonic development. The differential diagnoses of the congenital cheek fistula included orocutaneous fistulas and salivary fistulas. MRI was useful in delineating the border between the lesion and the surrounding tissue.

High failure rates following ligation of the intersphincteric fistula tract for transsphincteric anal fistulas: are preoperative MRI measurements of the fistula tract predictive of outcome?

AIM

Treatment of transsphincteric fistulas (TSFs) with fistulotomy after an indwelling seton is tempered by risks of incontinence and litigation. Thus, ligation of the TSF tract has been popularized as an alternative option. We previously reported on 107 patients who underwent ligation of the intersphincteric fistula tract (LIFT), with a 46% failure rate. Posterior fistula was the only predictor of recurrence. The aim of the present work was to investigate whether the length, width or depth of the fistula measured on preoperative MRI was correlated with recurrence.

METHOD

Following institutional review board approval, a retrospective analysis of our prospective Complex Anal Fistula Database from 1 January 2011 to 31 August 2019 was performed. Patients with TSF who underwent preoperative MRI and LIFT were included. Fistula location was classified as anterior, posterior or lateral. MRI measurements of fistula length, width and depth (in the intersphincteric groove) were performed. The type and rate of postoperative recurrence were analysed.

RESULTS

173 patients underwent MRI for an anal fistula; of these 40 underwent LIFT and 22/40 (55%) had preoperative MRI. There was no difference in the length, width or depth of anterior (n = 9), posterior (n = 7) or lateral (n = 6) fistula tracts. The overall recurrence rate was 9/22 (41%). Posterior TSFs had the highest recurrence rate (5/7, 71%).

CONCLUSION

The mean length, width, and depth of the fistula tract, measured at the preoperative site of LIFT in the intersphincteric groove, did not correlate with recurrence regardless of fistula location.

Significance and Impact of the Intersphincteric Plane Sepsis in the Management of the Perianal Sepsis: Ultrasound Study

Background The intersphincteric plane (ISP) is a potential space between the external and the internal anal sphincters. About 90% of the perianal sepsis is caused by an obstruction of the ducts of anal glands with subsequent secondary bacterial infection. The imaging modalities used to diagnose perianal sepsis are the ultrasound via endoanal and transperineal routes and magnetic resonance imaging.

Objective  The study aimed to identify the various patterns of the ISP sepsis and their incidence among our study group and to clarify the significance of ISP in the pathogenesis of anorectal abscesses and various types of perianal fistula tracts, to optimize the surgical management.

Methods Retrospective descriptive study in which 57 patients with an ISP sepsis were evaluated with full medical history, clinical exam, and ultrasound; the final diagnosis was based on combining the results of ultrasound, digital rectal examination under anesthesia, and the operative results.

Results The current study showed many patterns of the ISP sepsis and estimated the incidence of each pattern among our study group; such patterns could be fistula tracts, sinus tracts, abscesses, intersphincteric abscess with supralevator extension, sinus with abscess formation, fistula with abscess formation, distension of the ISP with free pus, and other complex patterns like horse abscess, abscess with transsphincteric sinus, and ISP fistula/sinus with transsphincteric branches.

Conclusion Understanding the role of the ISP in the pathogenesis of anorectal abscesses and perianal fistula tracts can help in reaching the optimum way of management.

Magnetic resonance imaging template to standardize reporting of anal fistulas

Anal fistula (AF) is a common referral to colorectal surgeons. Management remains challenging and sometimes controversial. Magnetic resonance imaging (MRI) is commonly performed in initial workup for AF. However, reports often lack key information for guiding treatment strategies. It has been shown that with structured radiology reports, there is less missing information. We present a structured MRI template report including 8 key descriptors of anal fistulas, whose effectiveness and acceptability are being assessed in a cross-sectional study (NCT04541238).

Recurrent anal fistulas: When, why, and how to manage?

Anal fistula is a commonly encountered anal condition in the surgical practice. Despite being a benign condition, anal fistula remains to represent a surgical challenge, particularly the complex type of fistulas. One of the common complications of anal fistula surgery is the persistence or recurrence of the pathology, both defined as failure of surgery. Recurrent anal fistulas after previous surgery represent an even more challenging problem since they are usually associated with a higher risk of re-recurrence and continence disturbance. The present review aimed to shed light on various aspects of recurrent anal fistulas, including the different definitions of failure after surgery, risk factors of recurrence, problems associated with management of recurrent fistulas, and assessment and treatment of recurrent anal fistulas.

Elucidating vaginal fistulas on CT and MRI

Vaginal fistulas (VF) represent abnormal communications between the vagina and either the distal portion of the digestive system or the lower urinary tract, but lack an accepted classification and standardised terminology. Regardless of the underlying cause, these uncommon disorders result in profound physical, psychological, sexual and social distress to the patients.Since diagnosis of VF is challenging at gynaecologic examination, ano-proctoscopy and urethro-cystoscopy, imaging is crucial to confirm the fistula, to visualise its site, course and involved organ, and to characterise the underlying disease. The traditional conventional radiographic studies provided limited cross-sectional information and are nowadays largely replaced by CT and MRI studies.Aiming to provide radiologists with an increased familiarity with VF, this pictorial paper summarises their clinical features, pathogenesis and therapeutic approach, and presents the appropriate CT and MRI acquisition and interpretation techniques that vary according to the anatomic site and termination of the fistula. The current role of state-of-the art CT and MRI is presented with examples regarding both entero- (involving the colon, rectum and anus) and urinary (connecting the bladder, distal ureter or urethra) VF. The resulting combined anatomic and functional cross-sectional information is crucial to allow a correct therapeutic choice and surgical planning.

Diagnostic Accuracy of Short Tau Inversion Recovery as a Limited Protocol for Diagnosing Perianal Fistula

Introduction

Perianal fistula refers to abnormal communication between perianal skin and anal canal. Magnetic resonance imaging (MRI) and endoanal ultrasound have been used in the evaluation of perianal fistula. Endoanal ultrasound is a cost-effective but operator-dependent technique. MRI provides accurate details regarding anal canal anatomy and effectively identifies the fistulae. For evidence-based care, a cost-effective and an accurate imaging modality is required in a developing country. Therefore, the aim of this study was to determine the diagnostic accuracy of short tau inversion recovery (STIR) as a limited protocol MRI pelvis in diagnosing perianal fistula taking surgical findings as the gold standard.

Materials and methods

A retrospective review of MRI pelvis from 1^st February 2018 to 1^st July 2018 was undertaken. Patients of any age or gender suspected to have perianal fistula were included. One radiologist interpreted the complete MRI pelvis and the other radiologist only viewed axial and coronal STIR sequences as a limited protocol. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy of axial and coronal STIR sequence were calculated taking surgical findings as the gold standard.

Results

In total, 150 patients were included in this study. The mean age of the patients was 43.20 ± 13.75 years. In total, 122 (81.3%) were males and 28 (18.7%) were females. Using STIR as a limited protocol, fistulae were found in 125 (83.3%) patients, whereas on surgery, the fistulae were found in 119 (79.3%) patients. Sensitivity, specificity, PPV, NPV, and diagnostic accuracy of STIR as limited protocol MRI pelvis in diagnosing perianal fistulae was found to be 96.6%, 67.7%, 92.0%, 84.0%, and 90.6%, respectively, taking surgical findings as the gold standard.

Conclusion

STIR has high sensitivity and diagnostic accuracy in diagnosing in the perianal fistula. Using STIR as a limited protocol in a developing country can help improving patient care by accurately diagnosing perianal fistulae. Moreover, it is recommended that further studies for identifying internal opening on STIR should also be carried out to improve patient care.

Complex anal fistula involving male genital tract: a new diagnostic entity

We present three male patients who had a rare presentation of anal fistula reaching the genital tract. Patient 1: a 44-year-old diabetic man presented initially to urology clinic complaining of penile and scrotal masses increasing in size for 6 months. Patient 2: a 67-year-old diabetic man presented with chronic sinus discharge from the scrotum. Patient 3: a 37-year-old diabetic man who presented with chronic sinus draining pus-like material from the scrotum for 1 year. Patients 1 and 2: following diagnosis of perianal fistula by MRI fistulography, complete excision of the fistula was done. This required tracking the fistula surgically, a perineal midline incision to release the fistula and excision of the fistula opening in the anal canal. The patients were doing well postoperative and no recurrence of fistula at 1-year follow-up. Patient 3: he refused surgical intervention. Penile mass or scrotal discharge has not been reported to be caused by fistula-in-ano.

Factors Increasing the Risk of Recurrence in Fistula-in-ano

Anal fistula, or fistula-in-ano, is a condition involving the anal region that is common yet debilitating. Surgery is the mainstay of treatment for an anal fistula and the chances of recurrence are quite high even after corrective surgical procedures. The risk factors for recurrence can be broadly classified into four categories: 1) risk factors related to the fundamental anatomy of the fistula and presence of comorbidities, 2) lack of proper preoperative assessment of the fistula, which includes failure to recognize the internal opening and overall structure of the fistula and not supplementing the proctologic examination with sufficient imaging, 3) intraoperative loopholes that include improper procedure selection, inexperience of the surgeon, and failure to get rid of the entire tract along with its ramifications, and 4) lack of proper postoperative care in the early and late periods following the surgery.

The aim of this paper, therefore, is to highlight the factors that could increase the risk of recurrence in different types of anal fistulae. Once surgeons know these risk factors, they can anticipate any complication and detect recurrence early.

Role of magnetic resonance imaging in the management of perianal Crohn's disease

Perianal fistulas are a major problem in many patients with Crohn's disease. These are usually complex fistulas that adversely affect patients' quality of life, and their clinical management is difficult. Medical treatment sometimes achieves cessation of discharge and closure of the external opening; however, it is difficult to assess the status of the rest of the fistula tract. Magnetic resonance imaging is the method of choice with which to evaluate the condition of perianal fistulas and allows for assessment of the status of inaccessible areas. Magnetic resonance imaging also allows the clinician to evaluate other perianal manifestations of Crohn's disease that differ from the fistulas. This imaging technique is therefore a fundamental means of patient monitoring. When used in conjunction with assessment of the patient's morphological findings, it provides information that allows for both quantification of disease severity and evaluation of the response to treatment. New types of magnetic resonance sequences are emerging, such as diffusion, perfusion, and magnetisation transfer. These sequences may serve as biomarkers because they provide information reflecting the changes taking place at the molecular level. This will help to shape a new scenario in the early assessment of the response to treatments such as anti-tumour necrosis factor drugs.

TEACHING POINTS

• MRI is the method of choice with which to evaluate perianal fistulas. • In perianal Crohn's disease, MRI is a fundamental means of patient monitoring. • The usefulness of the Van Assche score for patient monitoring remains unclear. • New MRI sequences' diffusion, perfusion, and magnetisation transfer may serve as biomarkers.

Prognostic factors affecting outcomes in fistulating perianal Crohn's disease: a systematic review

BACKGROUND

One in three patients with Crohn's disease will develop a perianal fistulae, and one third of these will achieve long-term healing or closure. A barrier to conducting well-designed clinical trials for these patients is a lack of understanding of prognostic factors. This systematic review sets out to identify factors associated with prognosis of perianal Crohn's fistulae.

METHODS

This review was registered on the PROSPERO database (CRD42016050316) and conducted in line with PRISMA guidelines along a predefined protocol. English-language studies assessing baseline factors related to outcomes of fistulae treatment in adult patients were included. Searches were performed on MEDLINE and Embase databases. Screening of abstracts and full texts for eligibility was performed prior to extraction of data into predesigned forms. Bias was assessed using the QUIPS tool.

RESULTS

Searches identified 997 papers. Following removal of duplicates and secondary searches, 923 were screened for inclusion. Forty-seven papers were reviewed at full-text level and 13, 2 of which were randomised trials, were included in the final qualitative review. Two studies reported distribution of Crohn's disease as a prognostic factor for healing. Two studies found that CARD15 mutations decreased response of fistulae to antibiotics. Complexity of fistulae anatomy was implicated in prognosis by 4 studies.

CONCLUSIONS

This systematic review has identified potential prognostic markers, including genetic factors and disease behaviour. We cannot, however, draw robust conclusions from this heterogeneous group of studies; therefore, we recommend that a prospective cohort study of well-characterised patients with Crohn's perianal fistulae is undertaken.

Magnetic Resonance Imaging (MRI) Characterization of Perianal Fistulous Disease in a Rural Based Tertiary Hospital of North India

Background

To diagnose and characterize the perianal fistulous disease using Magnetic resonance imaging (MRI) in a hilly and rural area of North India.

Material/Methods

This prospective hospital based study was conducted for a period of one year from April 2014 to April 2015 in the departments of Radiodiagnosis and Surgery of our institute. A total of 50 consecutive patients presenting with perianal fistulous disease fulfilling the inclusion and exclusion criteria were included in the study and taken up for MRI. The perianal fistulae were classified according to St James University hospital classification and tracks were assessed with regard to anatomical plane, length, ramifications, abscess formation, enteric communication, external cutaneous opening, enhancement and suprasphincteric extension. Surgical correlation was done in 31 patients who opted for surgical treatment. Rest of the 19 patients preferred alternative medicine for treatment or chose to postpone their surgery.

Results

The disease was much more prevalent in males in comparison to females with male to female ratio of 24:1. Grade 4 was the most common type of fistula (34%) while Grade 5 was the least common type (4%).MRI showed a high sensitivity of 93.7% and positive predictive value (PPV) of 96.7% when correlated with surgical findings. A substantial number of patients (38%) preferred alternative medicine or non surgical form of treatment.

Conclusions

MRI is a very sensitive modality for the evaluation of perianal fistula. In our study group, the disease predominantly affected middle aged men. Ramifications and abscesses were commonly seen, affecting nearly half of the patients and majority of the patients had active fistulous tracks with posteriorly located enteric opening. Overall, transsphincteric fistulae were most common. Significant number of patients avoided surgery or showed preference for non surgical treatment.

Clinical Significance of 2 Deep Posterior Perianal Spaces to Complex Cryptoglandular Fistulas

BACKGROUND

Confusion exists regarding the clinical significance of the deep posterior intersphincteric space and deep postanal space to complex perianal fistulas.

OBJECTIVE

The purpose of this study was to assess the clinical significance of the 2 deep posterior perianal spaces and to describe in detail the courses of posterior complex cryptoglandular fistula extensions.

DESIGN

This was a retrospective study. MRI-based characteristics of selected perianal fistulas were independently evaluated by examiners who focused on lesions in these 2 spaces and were blinded to each other's findings.

SETTINGS

This study was conducted in the colorectal surgery and radiology departments of a large university teaching hospital in China.

PATIENTS

Included in the study were patients who underwent pelvic MRI for posterior perianal fistula between October 2012 and December 2014.

MAIN OUTCOME MEASURES

The occurrence rates of these 2 deep perianal space lesions in posterior cryptoglandular fistulas were determined.

RESULTS

A total of 513 primary posterior cryptoglandular fistulas were identified in 508 patients, including 167 deep posterior intersphincteric space lesions (32.6%) and 23 deep postanal space lesions (4.5%). Of those, 173 fistulas (33.7%) were evaluated as complex. The former and latter spaces were involved in 79.2% (137/173) and 13.3% (23/173) of posterior complex fistulas. Compared with deep postanal space lesions, deep posterior intersphincteric space lesions were more common in cases with high transsphincteric or suprasphincteric fistulas (80.1% vs 15.8%), synchronous multiple transsphincteric fistulas (82.4% vs 20.6%), horseshoe-like fistulas (85.5% vs 14.5%), and supralevator fistulas (93.5% vs 16.1%). Similar incidences were also seen in cases with ischioanal-involved horseshoe-like fistulas (75.0% vs 25.0%).

LIMITATIONS

This study was limited by its retrospective nature.

CONCLUSIONS

The deep posterior intersphincteric space is more likely than the deep postanal space to be involved in complex cryptoglandular fistulas and is likely to play a more important role in the management of complex cryptoglandular fistulas.

Endosonography and magnetic resonance imaging in the diagnosis of high anal fistulae - a comparison

Anal fistula is a benign inflammatory disease with unclear etiology which develops in approximately 10 in 100 000 adult patients. Surgical treatment of fistulae is associated with a risk of damaging anal sphincters. This usually happens in treating high fistulae, branched fistulae, and anterior ones in females. In preoperative diagnosis of anal fistulae, endosonography and magnetic resonance imaging play a significant role in planning the surgical technique. The majority of fistulae are diagnosed in endosonography, but magnetic resonance is performed when the presence of high fistulae, particularly branched ones, and recurrent is suspected.

THE AIM OF THIS PAPER

The aim of this paper was to compare the roles of the two examinations in preoperative assessment of high anal fistulae.

MATERIAL AND METHODS

The results of endosonographic and magnetic resonance examinations performed in 2011-2012 in 14 patients (4 women and 10 men) with high anal fistulae diagnosed intraoperatively were subject to a retrospective analysis. The patients were aged from 23 to 66 (mean 47). The endosonographic examinations were performed with the use of a BK Medical Pro Focus system with endorectal 3D transducers with the frequency of 16 MHz. The magnetic resonance scans were performed using a Siemens Avanto 1.5 T scanner with a surface coil in T1, T1FS, FLAIR, T2 sequences and in T1 following contrast medium administration. The sensitivity and specificity of endosonography and magnetic resonance imaging were analyzed. A surgical treatment served as a method for verification. The agreement of each method with the surgery and the agreement of endosonography and magnetic resonance imaging were compared in terms of the assessment of the fistula type, localization of its internal opening and branches. The agreement level was determined based on the percentage of consistent assessments and Cohen's coefficient of agreement, κ. The integrity of the anal sphincters was assessed in each case.

RESULTS

In determining the fistula type, magnetic resonance imaging agreed with intraoperative assessment in 79% of cases, and endosonography in 64% of cases. Endosonography agreed with magnetic resonance in 57% of cases. In the assessment of internal opening, the agreement between endosonography and intraoperative assessment was 65%, between magnetic resonance and intraoperative assessment - 41% and between endosonography and magnetic resonance - 53%. In the assessment of fistula branches, endosonography agreed with intraoperative assessment in 67% of cases, magnetic resonance in 87% of cases, and the agreement between the two methods tested was 67%.

CONCLUSIONS

Magnetic resonance is a more accurate method than endosonography in determining the type of high fistulae and the presence of branches. In assessing the internal opening, endosonography proved more accurate. The agreement between the two methods ranges from 53-67%; the highest level of agreement was noted for the assessment of branching.

Magnetic resonance imaging (MRI) evaluation of perianal fistulae with surgical correlation

AIMS

The purpose of the study was to evaluate the role of Magnetic Resonance Imaging in detection and characterization of perianal fistulae and correlating it with surgical findings.

METHODS

Fifty consecutive patients with suspected perianal fistulae having one or more external openings were prospectively selected for MRI evaluation. Previously operated or patients with recurrent perianal disease were excluded from the study. MRI findings were recorded according to "St. James's University Hospital MR Imaging Classification of Perianal Fistulae" and correlated with surgical observations. Finally, comparison between T2-weighted fat saturated and postcontrast T1-weighted fat saturated sequences was done.

RESULTS

Amongst the total of 50 patients, per-operative findings confirmed perianal fistulae in 45 patients. The sensitivity and specificity of MRI in correctly detecting and grading the primary tract was found to be 95.56% and 80% respectively; for abscess, it was 87.50% and 95.24% respectively. High sensitivity was also discerned in identification of secondary tract (93.75%), correct localization of internal opening (95.83%) and for correctly detecting the horse-shoeing (87.50%). Our assumption of null hypothesis was accepted on comparing results of T2-weighted fat saturated sequences and postcontrast T1-weighted fat saturated sequences.

CONCLUSION

Magnetic Resonance Imaging (MRI) was highly accurate in assessment of surgically important parameters (primary tract and its grading, internal opening, secondary tract, abscess, horseshoeing) of perianal fistulae. Comparison of results of imaging findings on T2-weighted and postcontrast T1-weighted fat saturated sequences were statistically similar, so contrast study can be omitted, particularly while evaluating primary / previously unoperated perianal fistulae.

Comparison of different magnetic resonance imaging sequences for assessment of fistula-in-ano

AIM: To assess agreement between different forms of T2 weighted imaging (T2WI), and post-contrast T1WI in the depiction of fistula tracts, inflammation, and internal openings with that of a reference test.

METHODS: Thirty-nine consecutive prospective cases were enrolled. The following sequences were used for T2WI: 2D turbo-spin-echo (2D T2 TSE); 3D T2 TSE; short tau inversion recovery (STIR); 2D T2 TSE with fat saturation performed in all patients. T1WI were either a 3D T1-weighted prepared gradient echo sequence with fat saturation or a 2D T1 fat saturation [Spectral presaturation with inversion (SPIR)]. Agreement for each sequence for determination of fistula extension, internal openings, and the presence of active inflammation was assessed separately and blindly against a reference test comprised of follow-up, surgery, endoscopic ultrasound, and assessment by an independent experienced radiologist with access to all images.

RESULTS: Fifty-six fistula tracts were found: 2 inter-sphincteric, 13 trans-sphincteric, and 24 with additional tracts. The best T2 weighted sequence for depiction of fistula tracts was 2D T2 TSE (Cohen’s kappa = 1.0), followed by 3D T2 TSE (0.88), T2 with fat saturation (0.54), and STIR (0.19). Internal openings were best seen on 2D T2 TSE (Cohen’s kappa = 0.88), followed by 3D T2 TSE (0.70), T2 with fat saturation (0.54), and STIR (0.31). Detection of inflammation showed Cohen’s kappa of 0.88 with 2D T2 TSE, 0.62 with 3D T2 TSE, 0.63 with STIR, and 0.54 with T2 with fat saturation. STIR, 3D T2 TSE, and T2 with fat saturation did not make any contributions compared to 2D T2 TSE. Post-contrast 3D T1 weighted prepared gradient echo sequence with fat saturation showed better agreement in the depiction of fistulae (Cohen’s kappa = 0.94), finding internal openings (Cohen’s kappa = 0.97), and evaluating inflammation (Cohen’s kappa = 0.94) compared to post-contrast 2D T1 fat saturation or SPIR where the corresponding figures were 0.71, 0.66, and 0.87, respectively. Comparing the best T1 and T2 sequences showed that, for best results, both sequences were necessary.

CONCLUSION: 3D T1 weighted sequences were best for the depiction of internal openings and active inflammatory components, while 2D T2 TSE provided the best assessment of fistula extension.

A complex fistula-in-ano presenting as a soft tissue tumor

INTRODUCTION

Anorectal abscess and fistula are quite commonly encountered diseases. Both of these are the acute and chronic manifestations of the same entity. While abscess are thought to begin as an infection in the anal glands, their spreading into adjacent spaces results in a fistula formation. At many times this spread occurs in a complex pattern which is difficult to map and treat.

PRESENTATION OF CASE

This paper describes a complex perianal fistula that presented as a painless benign lump in the upper outer quadrant of the right buttock. The lump initially thought to be a soft tissue swelling was later diagnosed to be a chronic abscess cavity extending medially toward the anal canal in the form of a complex fistulous tract.

DISCUSSION

Complex perianal fistulas are difficult to treat and are prone to recurrences. Correct diagnosis and characterization of the fistula is essential to optimize the treatment. Clinical examination alone may not give a correct picture of the actual disease, thereby requiring radiological investigations like MRI.

CONCLUSION

Although rare, sometimes common clinical conditions like fistula-in-ano may also present in complex manner. It is important to establish the diagnosis firmly and map the fistula properly before going in for surgery. Complexity of fistulas and improper mapping often leads to recurrences and other complications like incontinence.