MR imaging evaluation of perianal fistulas: spectrum of imaging features

Management of Perianal Fistulizing Crohn's Disease

Perianal fistulizing Crohn's disease (CD) represents a severe phenotype of CD that is associated with significant morbidity and reduction in quality of life. Perianal fistulizing CD is caused by a complex interplay of genetic predisposition, immune dysregulation, gut dysbiosis, and various unknown physiological and mechanical factors. A multidisciplinary approach is hence required for optimal management . A detailed anatomical description and classification of perianal fistula, including comprehensive clinical, endoscopic, and radiological diagnostic workup, is an important prerequisite to treatment. For simple perianal fistulas, use of antibiotics and immunomodulators, with or without fistulotomy, are appropriate measures. The medical management of complex perianal fistula, on the other hand, requires adequate control of infection before initiation of therapy with immunomodulators. In active complex perianal fistula, anti-tumor necrosis factors remain the most accepted therapy, with concomitant use of antibiotics or immunomodulators enhancing the efficacy. For patients refractory to anti-tumor necrosis factors, treatment with anti-integrins, anti-interleukins, and small molecules is being evaluated. Mesenchymal stem cells, hyperbaric oxygen therapy, and exclusive enteral nutrition have also been investigated as adjunct therapies. Despite the expansion of the medical armamentarium, a large proportion of the patients require surgical interventions. In this review, we provide an up-to-date overview of the pathophysiology, clinical presentation, diagnosis, and medical management of perianal fistulizing CD. A brief overview of the surgical management of perianal fistulizing CD is also provided.

The analysis of different types of anorectal abscesses was conducted using the MRI 3D reconstruction technique

It has not yet been proven whether sepsis affects the tissue around the anal canal. To address this issue, we established three-dimensional models for various types of anorectal abscesses and utilize 3D reconstruction of Magnetic Resonance Imaging scans to assess the extent of muscle damage caused by anorectal abscesses. Patients diagnosed with anorectal abscess, selected from January 2019 to January 2022 underwent pre- and post-operative scanning of pelvic floor and perianal tissues. The aforementioned structures were segmented for the reconstruction of a three-dimensional visual model and measurement of volumes for the abscess as well as the internal and external sphincters and levator ani muscle. The study included a total of 42 patients. Three-dimensional visualization models were created for different types of anorectal abscesses, including perianal, intersphincteric, ischiorectal, and supralevator abscesses. No statistically significant differences were observed in the volume of the internal sphincter, external sphincter, and levator ani muscle between pre- and post-operative patients. The 3D model of anorectal abscess, reconstructed from MRI data, offers a precise and direct visualization of the anatomical structures associated with various types of anorectal abscesses. The infection did not result in any damage to the internal and external anal sphincter and levator ani muscle.

Current update on the role of endoanal ultrasound: a primer for radiologists

Endoanal ultrasound (EAUS) is a valuable imaging modality for the evaluation of anal and perianal pathologies. It provides detailed information about the anatomy and physiology of the anorectal region and has been used in pre-and post-operative settings of anorectal pathologies. EAUS is not only useful in the evaluation of benign pathologies but also in loco-regional staging of anal and rectal tumors. EAUS has several advantages over MRI, including reduced cost, better patient tolerance, and improved scope of application in patients with contraindications to MRI. Despite its benefits, EAUS is not widely performed in many centers across the globe. This article aims to educate radiologists, trainees, and surgeons about the indications, contraindications, patient preparation, imaging technique, and findings of EAUS. We will also highlight the technical difficulties, diagnostic challenges, and procedural complications encountered during EAUS, along with a comparative analysis of EAUS with other imaging approaches.

Dynamic contrast-enhanced MR imaging in identifying active anal fistula after surgery

BACKGROUND

It is challenging to identify residual or recurrent fistulas from the surgical region, while MR imaging is feasible. The aim was to use dynamic contrast-enhanced MR imaging (DCE-MRI) technology to distinguish between active anal fistula and postoperative healing (granulation) tissue.

METHODS

Thirty-six patients following idiopathic anal fistula underwent DCE-MRI. Subjects were divided into Group I (active fistula) and Group IV (postoperative healing tissue), with the latter divided into Group II (≤ 75 days) and Group III (> 75 days) according to the 75-day interval from surgery to postoperative MRI reexamination. MRI classification and quantitative analysis were performed. Correlation between postoperative time intervals and parameters was analyzed. The difference of parameters between the four groups was analyzed, and diagnostic efficiency was tested by receiver operating characteristic curve.

RESULTS

Wash-in rate (WI) and peak enhancement intensity (PEI) were significantly higher in Group I than in Group II (p = 0.003, p = 0.040), while wash-out rate (WO), time to peak (TTP), and normalized signal intensity (NSI) were opposite (p = 0.031, p = 0.007, p = 0.010). Area under curves for discriminating active fistula from healing tissue within 75 days were 0.810 in WI, 0.708 in PEI, 0.719 in WO, 0.783 in TTP, 0.779 in NSI. All MRI parameters were significantly different between Group I and Group IV, but not between Group II and Group III, and not related to time intervals.

CONCLUSION

In early postoperative period, DCE-MRI can be used to identify active anal fistula in the surgical area.

TRIAL REGISTRATION

Chinese Clinical Trial Registry: ChiCTR2000033072.

Early diagnosis of necrotizing fasciitis: Imaging techniques and their combined application

Necrotizing fasciitis is a clinical, surgical emergency characterized by an insidious onset, rapid progression, and a high mortality rate. The disease's mortality rate has remained high for many years, mainly because of its atypical clinical presentation, which prevents many cases from being diagnosed early and accurately, resulting in patients who may die from uncontrollable septic shock and multi-organ failure. But unfortunately, no diagnostic indicator can provide a certain early diagnosis of NF, and clinical judgement of NF is still based on the results of various ancillary tests combined with the patient's medical history, clinical manifestations, and the physician's experience. This review provides a brief overview of the epidemiological features of NF and then discusses the most important laboratory indicators and scoring systems currently employed to diagnose NF. Finally, the latest progress of several imaging techniques in the early diagnosis of NF and their combined application with other diagnostic indices are highlighted. We point out promising research directions based on an objective evaluation of the advantages and shortcomings of different methods, which provide a basis for further improving the early diagnosis of NF.

The Role of Magnetic Resonance Imaging in Pre-operative Assessment of Anorectal Fistula With Surgical Correlation

Background Anorectal fistulas are chronic inflammations of peri-anal tissues that form a connection between the perineal skin and the anal canal. Accurate preoperative evaluation of the main fistula's trajectory and pelvic tissues is essential for effective surgical treatment of anal fistulas. The inability to detect concealed lesions may result in the recurrence of fistulas and the conversion of a simple fistula into a complex fistula. Magnetic resonance imaging (MRI) imaging can detect concealed pathways and abscesses, thereby exposing the intricate connection between the fistula and anal-sphincter complex. This data serves as a roadmap for making surgical decisions, thereby reducing the likelihood of illness recurrence and complications after surgery. Aim To evaluate the role of MRI in pre-operative assessment of an anorectal fistula, compare its findings with surgical results. Materials and methods The research was conducted at the Radiology Department, Apollo Hospital, Hyderabad. It was a prospective observational study. IBM SPSS Statistics for Windows, Version 17 (released 2008; IBM Corp., Armonk, New York, United States) was utilized for data analysis. The mean and standard deviation were computed. We further applied appropriate statistical tests to determine the significance of MRI features with pre-operative findings. Results MRI accurately detects features like abscesses (sensitivity-100%, specificity-97.06%), secondary tracts of the fistula (sensitivity-93.55%, specificity-94.12%), horseshoe appearance, and supralevator extension (sensitivity-100%, specificity-97.50%, and 97.62%, respectively). Conclusion When comparing our results with intraoperative findings, MRI showed high sensitivity and specificity in detecting abscesses, secondary tracts, horseshoe appearances, and supralevator extensions. Our findings suggest that MRI can offer anatomical and pathological information for the pre-operative care and surgical planning of perianal fistulas.

Comparison of Contrast-Enhanced 3D Imaging with 2D Imaging in the Evaluation of Perianal Fistula at 3T: A Prospective Observational Study

Introduction  Perianal fistula and its recurrence is a challenging entity for surgeons. It is a well-establi1shed fact that magnetic resonance imaging (MRI) findings influence surgical procedures and reduce the rate of recurrence. In this study, we assessed the contrast-enhanced (CE) three dimensional T1 sequences [sampling perfection with application optimized contrast using different flip angle evolution (SPACE) and volumetric interpolated breath-hold examination (VIBE)] in a 3T MRI system to evaluate perianal fistulas and compared them with two-dimensional (2D) sequences. Materials and Methods  Forty-four patients (mean age, 38.8 ± 15.3 [standard deviation]; 32 males, 12 females) with perianal fistula were included in this prospective study. The patients underwent conventional noncontrast, 2D sequences, diffusion-weighted imaging, followed by postcontrast, 2D T1 images in both axial and coronal planes, and 3D sequences at 3T. Acquisition times were recorded for each sequence. Each postcontrast sequence was evaluated in terms of image quality, presence of artifacts, fistula type, presence of an abscess, visibility, and number of internal orifices. The surgical findings were considered the gold standard. The imaging findings were compared with the surgical findings. Results  In all three sequences, the fistula type and abscess were identified correctly in all patients. The sensitivity value for identification of ramifications utilizing CE 3D T1 VIBE sequence, CE 3D T1 SPACE, and CE 2D T1 images was 100, 86, and 36%, respectively. The number of internal orifices was identified by the CE 3D T1 VIBE and CE 3D T1 SPACE sequences in 100 and 92% of patients, respectively. CE 2D T1 images correctly identified internal orifices in 80% of patients. The overall scan time for each 3D sequence was shorter than for the combined postcontrast 2D sequences. Conclusion  CE 3D T1 SPACE and CE 3D T1 VIBE sequences outperformed conventional CE 2D sequences in the evaluation of perianal fistulas in terms of visibility and the number of internal orifices with a shorter scanning time. Among the 3D sequences, CE 3D T1 VIBE is slightly superior to CE 3D T1 SPACE sequence.

Extraprostatic incidental findings on prostate mpMRI: A pictorial review from the ESUR junior network

The role of multiparametric MRI (mpMRI) in prostate cancer setting is increasingly consolidated and, as a result, its usage in clinical practice is in exponential growth. However, beyond the prostate gland, several key structures are included in the field of view of mpMRI scans. Consequently, various extra-prostatic incidental findings (IFs) belonging to different anatomical systems can be accidentally recognized. Therefore, it is mandatory for a radiologist to be familiar with the wide range of pathologies potentially encountered, to guide management and avoid patient anxiety and costs due to additional work-up prompted by clinically insignificant extra-prostatic findings. With this pictorial review, we aim to illustrate a wide range of IFs that can be detected when performing mpMRI of the prostate, focusing on their imaging characteristics, differential diagnosis, and clinical relevance. Additionally, we propose the CheckDEEP, the Checklist for DEtection of ExtraProstatic findings, to be used for a thorough evaluation of target areas within each anatomical system.

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.

Incidence and diagnostic performance of ultrasound for perianal abscess or fistula-in-ano in pediatric patients with perianal inflammation

OBJECTIVES

To describe the incidence and diagnostic performance of ultrasound for perianal abscess or fistula-in-ano in pediatric patients with perianal inflammation.

METHODS

We included 45 patients with perianal inflammation who underwent ultrasonography. To demonstrate the diagnostic performance of ultrasound for fistula-in-ano, a definite diagnosis of perianal abscess, and fistula-in-ano was determined as that proven through magnetic resonance imaging (MRI) or computed tomography (CT). The absence or presence of perianal abscess and fistula-in-ano on ultrasonography was recorded.

RESULTS

Among the 45 patients, on ultrasound, perianal abscess and fistula-in-ano were detected in 22 (48.9%) and 30 (68.2%) patients, respectively. Nine patients had MRI or CT and a definite diagnosis of perianal abscess or fistula-in-ano; accuracy, negative predictive value, and positive predictive value of ultrasound for perianal abscess were 77.8% (7/9; 95% confidence interval [CI]: 40.0%-97.1%), 66.7% (2/3; 95% CI: 9.4%-99.2%), 83.3% (5/6; 95% CI: 35.9%-99.6%), and those of fistula-in-ano were 100% (9/9; 95% CI: 66.4%-100%), 100% (8/8; 95% CI: 63.1%-100%), and 100% (1/1; 95% CI: 2.5%-100%), respectively.

CONCLUSIONS

Perianal abscess and fistula-in-ano were detected by ultrasound in half of the patients with perianal inflammation. Accordingly, ultrasound has an acceptable diagnostic performance for perianal abscess and fistula-in-ano.

[Perianal Fistula: An Overview]

Perianal fistula is a common inflammatory condition in the general population and affects the area around the anal canal. Although most cases are benign, they cause serious morbidity and require surgical treatment due to a high risk of recurrence. MR imaging is a gold standard technique for the evaluation of perianal fistulas and provides accurate information on the anatomy of the anal canal, its relationship to the anal sphincter complex, accurate identification of secondary tracts or abscesses, and reporting associated complications. MR imaging can help monitor treatment effects and determine treatment methods. Crohn's disease-related fistulas often require medical rather than surgical treatment. The radiologist is required to know the anatomy and MR imaging findings of the perianal fistula to present an accurate diagnosis to the clinician.

Surgery of Simple and Complex Anal Fistulae in Adults: A Review of the Literature for Optimal Surgical Outcomes

Anal fistulas are common anorectal conditions, and surgery is the primary treatment option. In the last 20 years of literature, there exist a large number of surgical procedures, especially for the treatment of complex anal fistulas, as they present more recurrences and continence problems than simple anal fistulas. To date, there are no guidelines for choosing the best technique. We conducted a recent literature review, mainly the last 20 years, based on the PubMed and Google Scholar medical databases, with the goal of identifying the surgical procedures with the highest success rates, lowest recurrence rates, and best safety profiles. Clinical trials, retrospective studies, review articles, comparative studies, recent systematic reviews, and meta-analyses for various surgical techniques, as well as the latest guidelines of the American Society of Colon and Rectal Surgeons, the Association of Coloproctology of Great Britain and Ireland, and the German S3 guidelines on simple and complex fistulas were reviewed. According to the literature, there is no recommendation for the optimal surgical technique. The etiology, complexity, and many other factors affect the outcome. In simple intersphincteric anal fistulas, fistulotomy is the procedure of choice. In simple low transsphincteric fistulas, the patient's selection is crucial in order to perform a safe fistulotomy or another sphincter-saving technique. The healing rate in simple anal fistulas is higher than 95% with low recurrence and without significant postoperative complications. In complex anal fistulas, only sphincter-saving techniques should be used; the optimal outcomes are obtained by the ligation of the intersphincteric fistulous tract (LIFT) and rectal advancement flaps. Those techniques assure high healing rates of 60-90%. The novel technique of the transanal opening of the intersphincteric space (TROPIS) is under evaluation. The novel sphincter-saving techniques of fistula laser closure (FiLac) and video-assisted anal fistula treatment (VAAFT) are safe, with reported healing rates ranging from 65% to 90%. Surgeons should be familiar with all sphincter-saving techniques in order to face the variability of the fistulas-in-ano. Currently, there is no universally superior technique that can treat all fistulas.

Tumor-Bowel Fistula as a Rare Form of Recurrent Ovarian Cancer-Imaging and Treatment: Preliminary Report

BACKGROUND

The aim of this pilot study was to evaluate the value of imaging techniques, including computed tomography (CT) and magnetic resonance imaging (MRI), in the diagnosis of a tumor-bowel fistula as a rare form of epithelial ovarian cancer (EOC) relapse. We also performed an initial assessment of the effectiveness of the treatment of this form of relapse.

METHODS

The study group consisted of eight patients with suspected platinum-sensitive recurrence in the form of a tumor/bowel fistula. All patients finished their first line of chemotherapy and subsequently showed complete remission for 6 months or more. To qualify patients for further treatment, CT and MRI were performed, which suggested the presence of a fistula between the recurrent tumor and intestine. DESKTOP study criteria were used to qualify patients for secondary cytoreduction. Second-line chemotherapy was given after secondary debulking.

RESULTS

In all patients, fistulas formed between the tumor and large bowel. On CT, the fistulas were indirectly visible. In all cases, the fistula was visible on MR images, which showed hypointensity on the T2 and T1 post-contrast sequences but did not show restricted diffusion on the diffusion-weighted imaging (DWI) sequence. Patients who were qualified for the study underwent secondary debulking with bowel resection. In all eight cases, the fistula between the tumor and surrounding organs was confirmed. During surgery, seven intestinal anastomoses and one colostomy were performed. No residual macroscopic tumor remained in seven cases (resection R0-87.5%). The progression-free survival (PFS) was 8.4-22.6 months (median 13.4). In the group with cytoreduction R0, the median PFS was 15.5 months (12-22).

CONCLUSION

In patients with suspected EOC recurrence with clinically suspected fistula, CT scan is not sufficient. In CT, the presence of a fistula is suspected based on indirect symptoms. MRI, as a method with much greater tissue resolution, confirms the diagnosis. In addition, MRI can identify the point of the tumor/bowel junction. This is especially true with a large infiltration covering several intestinal parts. Bowel resection with simultaneous anastomosis is a good and safe solution for these patients. However, appropriate qualification for the procedure is necessary, which will allow for surgery without residual macroscopic disease (R0 surgery). Due to the small number of cases, our results cannot be generalized. We treat them as a hypothesis that can be verified in a larger study.

The pathogenesis of cryptoglandular anal fistula: New insight into the immunological profile

AIM

The aetiology of cryptoglandular anal fistula (AF) is poorly understood. Evidence suggests that persistence and/or recurrence of the disease is more related to inflammatory than infectious factors. The aim of this study was to investigate the immune profile of cryptoglandular AF and to perform a histopathological characterization.

METHOD

Fistulectomy was performed in all patients; healthy ischioanal fat from the same patients was used as a control. Samples were evaluated by the Luminex xMAP system for the detection of 27 analytes. AF tissues were analysed using immunofluorescence. Staining was performed using primary antibodies to identify M1 inflammatory and M2 anti-inflammatory macrophages. Selective staining of total T lymphocytes and different T lymphocyte subsets was performed.

RESULTS

Twenty patients with AF underwent a fistulectomy. Specific cytokine pathways differentiated AF from healthy tissue: pro-inflammatory cytokines interleukin (IL)-1β, IL-4, IL-8 and IL-17 and the anti-inflammatory cytokine IL-10 were overexpressed in AF compared with controls. Chemokines involved in macrophage recruitment (CCL2, CCL3, CCL4) were higher in AF than in healthy fatty tissue. Moreover, we showed that Tc17 cells characterize AF patients, thus confirming the enzyme-linked immunosorbent assay data. Furthermore, elevated infiltration of CD68+ myeloid cells and a reduction of the M1/M2 ratio characterize AF patients.

CONCLUSION

A combination of inflammatory cytokines, chemokines and growth factors reside in the wound microenvironment of AF patients. For the first time an important prevalence of Tc17 cells and a reduction in the M1/M2 ratio was observed, thus suggesting new insights into the immunological characterization of AF patients.

MRI of Recurrent Fistula-in-Ano: Is it Different from Treatment-Naïve Fistula-in-Ano and How Does it Correlate with Anal Sphincter Morphology?

Objectives  The main aim of this study was to compare magnetic resonance imaging (MRI) findings of recurrent and treatment-naïve fistula-in-ano and to correlate imaging findings with anal sphincter morphology in recurrent fistula-in-ano. Methods  This is a retrospective study of adult patients who underwent MRI for suspected fistula-in-ano in 2018. After excluding patients with alternative diagnosis, patients were stratified into recurrent ( n  = 103) and treatment-naïve ( n  = 106) fistula-in-ano groups. Two blinded radiologists reread MRI scans in consensus for fistula characteristics and anal sphincter morphology. We compared imaging features of recurrent and treatment-naïve fistula-in-ano, assessed the incidence of anal sphincter scarring among patients with recurrent fistula-in-ano, and studied its association with fistula features. Results  Two-hundred nine patients (187 males) with mean age of 40.6 (standard deviation: 12.2) years were included. Trans-sphincteric, inter-sphincteric, extra-sphincteric, and supra-sphincteric fistula-in-ano were seen in 63.6, 33, 2.9, and 0.5%, respectively. There were secondary tracts, supralevator extension, and secondary cause for fistula in 49.3, 12.9, and 14.8%, respectively. There was no difference between the fistula features of recurrent and treatment-naïve fistula-in-ano, except for significantly fewer external openings among recurrent fistula-in-ano ( p  = 0.005). Among patients with recurrent fistula-in-ano, MRI detected anal sphincter defect/scarring was seen in 53.4% ( n  = 55) and was significantly associated with posterior fistula-in-ano ( p  = 0.031), collections and/or supralevator extension ( p  = 0.010), and secondary tracts ( p  = 0.015). Conclusion  Fistula features of recurrent and treatment-naïve patients were mostly similar. There was high incidence (53.4%) of MRI-identified anal sphincter scarring/defect among recurrent fistula-in-ano, which was significantly associated with posterior fistula, collections, supra or translevator extension, and secondary tracts. Key Points MRI-identified anal sphincter scarring is very common among patients with recurrent fistula-in-ano and seen in more than half of them.There was significantly higher incidence of sphincter scarring among patients who had posterior fistula, collections, supralevator/translevator extension, and secondary tracts.

Utility of Diagnostic Imaging in the Early Detection and Management of the Fournier Gangrene

Fournier gangrene represents a urologic emergency. It is a rapidly progressing necrotizing fasciitis that comprises the perineal, perianal, and genital regions and has a high mortality rate. Diagnosis is usually made clinically, but radiological diagnostics, such as ultrasound (US), computed tomography (CT), or magnetic resonance imaging (MRI), can determine the extent of the disease in relation to pelvic structures. Early and accurate diagnosis precipitates the initiation of the effective treatment and, thus, affects the outcome of the therapy. The article reports an illustrative case study of a patient with Fournier gangrene, secondary to a perianal fistula and perianal abscess with a massive accumulation of fluid around the anus and testicles, requiring unilateral orchidectomy. Rapid radiological diagnosis via MRI enabled precise assessment of the degree of the disease, early surgical intervention, and a successful outcome.

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.

Fistula in Ano-A 2-Year Prevalence Study on North Indian Rural Population

Perianal fistula (PF) is a common inflammatory condition affecting the perianal region including the sphincter muscles, ischioanal fossae, and the perianal skin. It is notorious to recur and, as a result, causes significant morbidity in both urban and rural population. Magnetic resonance imaging (MRI) has revolutionized imaging in PFs as it provides excellent anatomical visualization of the fistulous tracts, their origin, course, number, chronicity, opening in the external and internal anal sphincter, length of sphincter, evidence of active disease and abscess formation along the tract. It is also very useful in presurgical mapping and reduce the chances of recurrence. Most of the studies done on PFs are based on the urban population. Rural population have a completely different lifestyle which makes them susceptible to various diseases, less prevalent in the urban population. Hence, the purpose of this article is to find the prevalence of different grades in North Indian rural region close to the NCR (National Capital Region). In the study including 98 patients, the maximum number of patients were classified into grade 1 and grade 4 by MRI according to St. James' University Hospital MRI classification. This is the second reported study on prevalence of different grades of PFs in rural population in India. The higher prevalence of grade 4 PFs in our study might be secondary to illiteracy, social stigma, poor hygiene, or higher recurrence rate. Closely understanding the difference in dynamics of urban and rural population, our goal of the study is to determine the prevalence of different grades of PFs in the rural population. We also aim to familiarize physicians, radiologists, and surgeons with the MRI evaluation and grading of PF to help in presurgical mapping and thus, reducing the chances of recurrence. We also recommend further studies to evaluate psycho-social factors as a barrier in seeking early medical care in rural population.

The Role of Magnetic Resonance Enterography in Crohn’s Disease: A Review of Recent Literature

Inflammatory bowel disease (IBD) is the term used to identify a form of chronic inflammation of the gastrointestinal tract that primarily contemplates two major entities: ulcerative colitis (UC) and Crohn’s disease (CD). The classic signs are abdominal pain and diarrhoea that correlate with the localization of gastro-enteric disease, although in this pathology extraintestinal symptoms may coexist. The diagnosis of CD relies on a synergistic combination of clinical, laboratory (stool and biochemical), cross-sectional imaging evaluation, as well as endoscopic and histologic assessments. The purpose of this paper is to prove the role of imaging in the diagnosis and follow-up of patients with CD with particular focus on recent innovations of magnetic resonance enterography (MRE) as a pivotal diagnostic tool, analysing the MRE study protocol and imaging features during the various phases of disease activity and its complications.

Anorectal pathology in the HIV population: a guide for radiologists

Patients with human immunodeficiency virus (HIV) can present with a wide range of different acute and chronic pathologies. Anorectal conditions are particularly common in this unique patient population, including pathologies, such as proctitis, anorectal abscess, anorectal fistula, and anal squamous cell carcinoma. The radiologist plays a critical role in the assessment of these common forms of anorectal disease, as these conditions can present with various findings on imaging assessment. Pelvic CT, MRI, and FDG-PET/CT are among the most common modalities used for assessment of anorectal disease in the HIV patient population. Knowledge of the fundamental clinical and imaging findings associated with these pathologies in HIV patients is critical for radiologists.

Overview of the Large Bowel Assessment Using Magnetic Resonance Imaging: Different Techniques for Current and Emerging Clinical Applications

Radiological assessments of the small and large bowel are essential in daily clinical practice. Over plain film X-ray and ultrasound, cross-sectional techniques are considered the most comprehensive imaging modalities. In fact, computed tomography and magnetic resonance imaging take great advantage of the three-dimensional appraisal and the extensive evaluation of the abdominal cavity, allowing intestinal evaluation as well as detection of extra-intestinal findings. In this context, the chief advantage of computed tomography is the fast scan time, which is crucial for emergency cases. Nonetheless, it is undeniably impaired using ionizing radiation. As the awareness of radiation exposure is a topic of increasing importance, magnetic resonance imaging is not only becoming a mere alternative but also a primary imaging technique used in assessing intestinal diseases. Specifically, the evaluation of the large bowel through MRI can be still considered relatively uncharted territory. Although it has demonstrated superior accuracy in the assessment of some clinical entities from inflammatory bowel disease to rectal carcinoma, its role needs to be consolidated in many other conditions. Moreover, different technical methods can be applied for colonic evaluation depending on the specific disease and segment involved. This article aims to provide a thorough overview of the techniques that can be utilized in the evaluation of the large bowel and a discussion on the major findings in different colonic pathologies of primary interest.

Perianal magnetic resonance imaging findings and their potential impact on outcome in children with perianal fistulizing Crohn disease

BACKGROUND

Children with perianal fistulizing Crohn disease require intensive medical management but also have a higher risk for subsequent surgical interventions.

OBJECTIVE

We performed a retrospective study to identify patient factors and perianal anatomical features by pelvic MR that are associated with surgical interventions in these children.

MATERIALS AND METHODS

We included children with Crohn disease and perianal fistula who underwent pelvic MR with available, archived images and collected demographic, clinical and laboratory data. Radiologists reviewed pelvic MR exams and identified Park classification and additional anatomical features of perianal fistulas, including fistula branching, horseshoe ramifications, abscess, inflammatory mass, supralevator extension, anal sphincter damage, proctitis and posterior anal space involvement. We performed univariate and subsequent multivariate analysis to determine features associated with subsequent surgical intervention.

RESULTS

Ninety-nine children with Crohn disease underwent pelvic MR. In this cohort, 69 children had no surgical interventions prior to baseline MRI, with subsequent median clinical follow-up of 5.5 years. Univariate analysis demonstrated that branching (P=0.009), supralevator extension (P=0.015) and anal sphincter damage (P=0.031) were significantly associated with subsequent surgical intervention. Age at baseline MRI was also associated with intervention (hazard ratio [HR] every 5 years: 2.13; 95% confidence interval [CI]: 1.18-3.83; P=0.012). A multivariable model identified only fistula branching (HR: 2.31; 95% CI: 1.28-4.15; P=0.005) and age (HR: 5.18; CI: 1.57-17.14; P=0.007) as independent predictors of subsequent surgery. No demographic, clinical or laboratory parameter predicted subsequent surgical intervention.

CONCLUSION

Age and anatomical MR features indicating fistula complexity (branching, supralevator extension) and sphincter damage confer a higher risk of subsequent surgical intervention in children with perianal Crohn disease.

CT and MRI Evaluations in Crohn's Complications: A Guide for the Radiologist

Inflammatory bowel diseases (IBD) are a group of chronic inflammatory intestinal conditions with unknown etiology. Crohn's disease (CD) and ulcerative colitis (UC) are the two main types of IBD and they have some interchangeable and some different clinical and pathological characteristics. When diagnosis is performed for the first time, the majority of CD patients have a predominant inflammatory condition. As the disease progresses most patients experience the development of complications, such as abscesses, fistulas, perforation, strictures, and others. Both computed tomography (CT) and Magnetic Resonance Imaging (MRI) allow great view of the whole length of the intestinal tract together with the eventual extra-and intra-intestinal complications. MR enterography (MRE) and CT enterography (CTE), performed after oral administrations of contrast medium, have similar diagnostic accuracy for the diagnosis of CD and its complications. Even though CT is still the most familiar diagnostic technique used for studying CD worldwide, MRE have several important benefits that are leading to rapid increase in its employment in the last years. In particular, MRE allows a superior soft tissue contrast resolution compared to CT, offering a better visualization of bowel wall and its inflammatory and fibrotic characteristics. Moreover, Pelvic Magnetic Resonance is the principal technique in patients with perianal disease due to its ability of providing precise and fine detail images of the sphincter complex, which are crucial for evaluating pelvic disease. In this paper we describe common and uncommon complications in patients with CD, and explain how to identify their findings in CT and MR exams.

Perianal Inflammation or Something More?

Perianal fistulae are commonly complicated by abscesses and ramifications, which have well-recognized imaging morphology. Less commonly, atypical findings of solid enhancing mass-like lesions with no fluid component are associated with chronic and recurrent fistulae, the etiology of which includes inflammatory masses as well as locally aggressive malignancy. The latter predicts poorer prognosis and warrants extensive surgical resection. The reading radiologist must identify the unusual appearance, be aware of the possible etiologies, and if appropriate recommend prompt tissue sampling to exclude malignancy. This is pertinent as it determines surgical management, which is crucial in achieving a potential curative outcome.

Management of sacrococcygeal pilonidal sinus disease in children: A survey study in Turkey

Objective: Sacrococcygeal pilonidal sinus disease is common in children. The disease reduces the quality of life of patients with symptoms such as pain and chronic discharge. Variable surgical techniques have been described for the treatment of pilonidal sinus disease. This study aims to evaluate clinical approach of Turkish pediatric surgeons to children with pilonidal sinus disease.

Material and Methods: Survey questions were prepared through a literature review for controversial issues. The participants were asked pre-selected and checkbox questions. The survey was sent to 450 pediatric surgeons, members of the Association of Turkey Pediatric Surgery via a link to Google Forms.

Results: Nineteen percent (88) of the members responded. Seventy five (85.2%) of the pediatric surgeons stated that they did not perform additional preoperative imaging. Surgical excision methods were preferred more than minimally invasive procedures (102 to 46). Sixty (68.2%) of the participants preferred preoperative prophylactic single dose intravenous antibiotics and postoperative oral antibiotics. Regarding the participants’ practices, poor local hygiene, overweight, wide or deep sinus pit were stated as the most common causes of recurrence. Vast majority of the pediatric surgeons recommended laser epilation (%85.2) and slimming (59.1%) to patients.

Conclusion: Various studies have been published from Turkey for pilonidal sinus disease. As seen in the current study, Turkish pediatric surgeons do not have a common opinion in pilonidal sinus disease and prefer surgical excision methods more frequently. Prospective randomized studies with bigger number of patients are required to establish common guidelines in disease management.

The new pathways of spread of anal fistula and the pivotal role of MRI in discovering them

Conventionally, in the pathophysiology of anal fistulas, there is only one space considered significant for the spread of pus in the sphincter complex: the intersphincteric space. However, with increasing experience in the high-resolution MRI, and more focus being given on managing fistulas through the intersphincteric space, two additional pathways of fistula spread have been identified. First is a newly described space labelled as the outer-sphincteric space. Second is a known anatomical space (inner intersphincteric space), but this space was considered as irrelevant from the point of view of fistula spread. The conventional intersphincteric space is present in between these two spaces and is referred as 'middle intersphincteric space' in this paper. These three distinct spaces have significant clinical implications as the pattern of spread of pus is quite different in each space, and the management also differs for fistula tract in each of these spaces.

Magnetic Resonance Imaging of Perianal Fistulas in Clinically Symptomatic Patients and the Correlation Among Plain, Contrast, and Post Jelly MRI Fistulography

Objectives To evaluate different types of perianal fistulas and their complications on magnetic resonance imaging (MRI) and to compare plain, contrast, and jelly magnetic resonance fistulography findings.

Materials and Methods This prospective study was performed in 30 patients who presented with perianal pus discharge or external fistulous opening. Magnetic resonance imaging of the perianal region before and after giving intravenous contrast and after injecting jelly through a percutaneous opening was performed on a 3T scanner and the results were correlated.

Results The mean age of the patients was 40.13 ± 13.88 years (range 19–75 years). The male to female ratio was 14:1. The most common type of fistula was St. James classification type I, which was seen in 13 patients (43%), followed by type IV in 30%, type III in 16%, type II in 6.66%, and type V in 3.33% of the patients. Using agreement analysis, we compared the number of primary and secondary tracts, internal openings, and horseshoe tracts and found a significant agreement between plain and post Jelly MRI fistulography (kappa statistic close to 1). When comparing plain and contrast MRI, there was significant agreement in the primary and secondary tracts, while statistically insignificant results were obtained (p > 0.05) for the horseshoe tract and internal openings. Contrast injection was helpful in 7 subjects (23.3%) as peripheral enhancement of abscesses were better delineated.

Conclusion Magnetic resonance imaging is the one stop diagnostic modality for perianal fistulas. Acquisition of axial (Ax) T2, axial T2 FS, coronal T2 and coronal T2 FS sequences without administering intravenous contrast or jelly is usually sufficient for the diagnosis of fistulas and their complications.

Postoperative complications of colorectal cancer

Colorectal cancer is the third most common cancer, and surgery is the most common treatment. Several surgical options are available, but each is associated with a range of potential complications. The timely and efficient identification of these complications is vital for effective clinical management of these patients in order to minimise their morbidity and mortality. This review aims to describe the range of commonly performed surgical treatments for colorectal surgery. In addition, frequent post-surgical complications are explored with investigative options explained and illustrated.

Role of Diffusion-Weighted Imaging in the Evaluation of Perianal Fistulae

Background  Magnetic resonance imaging (MRI) is the imaging modality of choice for evaluating perianal fistulae, due to its ability to show the relationship of perianal fistulae with anal sphincters, fistula extensions, secondary ramifications and associated complications.

Aim  To evaluate the role of diffusion-weighted MRI in the evaluation of perianal fistulae.

Settings and Design  A hospital-based cross-sectional study.

Materials and Methods  The study group composed of 47 patients of perianal fistula. MRI with diffusion-weighted imaging (DWI) was performed with Philips 0.5 T Ingenia scanner. DWI with different b -values ( b = 50, b = 400, and b = 800 smm ² ) were obtained. The MRI findings were correlated with local clinical examination and or surgical findings.

Statistical Analysis Used  Chi-square test, independent samples t -test, and receiver operating characteristic curve analysis.

Result  Fifty-nine perianal fistulas in 47 patients were included in the study sample. The visibility of perianal fistula on DWI was less than T2-weighted (T2W) and combined DWI-T2W images. Distinctly visualized (visibility score 2) perianal fistulas were observed in 47 fistulas (79.6%) on DWI, 54 (91.5%) on T2W, and 58 (98.3%) on DWI-T2W images. The mean of apparent diffusion coefficient (ADC) values of active fistula was 0.972 ± 0.127 [SD] 10 ⁻³ mm ² /s and inactive was 1.232 ± 0.185 [SD] 10 ⁻³ mm ² /s with a significant difference ( p -value < 0.0005). A cut-off mean ADC value of 1.105 × 10 ⁻³ mm ² /s was used to differentiate active from the inactive fistula with a sensitivity of 87.5% and specificity of 73.3%.

Conclusion  Combined DWI-T2W evaluation had a better performance in the detection of fistula than DWI or T2W alone. DWI with mean ADC calculation had a good performance in differentiating active from the inactive fistulas.

MRI of Perianal Crohn Disease: Technique and Interpretation

ABSTRACT

Magnetic resonance imaging (MRI) has emerged as the imaging method of choice for evaluation of perianal fistulizing disease. As treatment of Crohn disease and associated perianal fistulas has evolved to include a combination of systemic treatments and surgical interventions, perianal MRI provides critical information to guide treatment selection and timing. Radiologists need to be familiar with the normal regional anatomy to accurately describe perianal fistulas and any associated complications which can then be used to classify fistulas based on several available classification systems. Following treatment, MRI can provide information that suggests treatment success or failure. We propose a perianal fistula reporting template that includes the necessary information to convey fistula complexity, guide treatment, and evaluate treatment response. This review article will also discuss the postoperative appearance of many treatments currently used for management of perianal fistulizing disease and some associated complications.

Best non-contrast magnetic resonance imaging sequence and role of intravenous contrast administration in evaluation of perianal fistula with surgical correlation

PURPOSE

To evaluate the best non-contrast magnetic resonance imaging (MRI) sequence and role of intravenous contrast administration in preoperative characterization and classification of perianal fistulae, keeping surgery as gold standard.

METHODS

This prospective study comprised of forty-five consecutive patients with actively draining external perianal opening. MRI was performed on a 1.5 T scanner using non-contrast and contrast enhanced sequences in multiple planes. St. James's University Hospital MRI based classification system was used to classify the fistulae into five grades. Taking surgery as gold standard, association between surgical and MRI findings was statistically analysed.

RESULTS

Of the 45 patients recruited, forty were deemed eligible for inclusion. Mean age was 39.7 ± 11.7 years with male preponderance (M: F = 8:1). Commonest type was Grade 1 (40%). The best sequences in terms of overall accuracy were axial & coronal planes of contrast enhanced fat suppressed (FS) T1W turbo spin echo (TSE) (95.7%) followed by FS T2W TSE (94.1%) while sagittal T2W TSE sequence with or without fat suppression had the lowest accuracy (90.13%). The difference in overall diagnostic accuracy of FS T2W TSE and contrast enhanced FS T1W TSE sequence for evaluating perianal fistula was not statistically significant (p = 0.52). However, contrast study had a better accuracy in detecting internal openings and secondary tract of recurrent/ post-operative cases.

CONCLUSION

Best non-contrast MRI sequence is FS T2W TSE (axial and coronal). Non-contrast MRI is equally efficient to contrast study while evaluating primary/previously unoperated cases thereby eliminating the role of contrast in such cases. However, intravenous contrast should be administered for evaluating post-operative cases with recurrence.

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).

Current imaging techniques for evaluation of fistula in ano: a review

Background

Fistula in ano is one of the common anorectal disorders which have a tendency to recur specially in complex cases usually due to missed or undetected sepsis at the time of examination or surgery. A correct identification of the primary source of crypt infection along with a complete understanding of the anatomical course of primary and secondary tracks and abscesses is a prerequisite for the successful management of fistula. Preoperative evaluation of fistula in ano using radio-imaging techniques provides a handy insight of fistula anatomy and helps in planning the appropriate treatment strategy. The objective of this article is to review the role of different radio-imaging techniques in the diagnosis and evaluation of fistula in ano along with their advantages and disadvantages over one another.

Main text

A comprehensive literature review was performed searching through the electronic databases as well as the standard textbooks of colorectal surgery. X-rays (plain radiographs and contrast fistulography), computed tomography (CT) scanning, anal endosonography, and magnetic resonance (MR) imaging are the modalities used for preoperative imaging of fistula in ano. Due to low accuracy, X-ray fistulography is not used now for fistula imaging. CT fistulography can be more accurate in cases associated with acute inflammations and abscesses and the fistulas related with inflammatory bowel disease. Anal endosonography and MRI are two of the mostly used and reliable imaging techniques for fistula in ano. Though the use of a 3D technology has improved the accuracy of anal endosonography, MRI is the preferred choice by many. However, various reports have depicted comparable accuracies for both MRI and anal endosonography showing both to be equally sensitive but MRI to be more specific. 3D endoanal ultrasound, on the other hand, is more rapid and can also be used intraoperatively to provide live imaging during surgical exploration.

Conclusion

Complex and recurrent fistula cases should undergo a preoperative imaging to reduce the chances of recurrence. MRI is recommended as the imaging modality of choice for such cases. 3D anal endosonography may however be a good option over MRI owing to its rapidity, availability, and potential of intraoperative assistance during surgery.

Magnetic Resonance Imaging of the Anal Region: Clinical Applications

Over the past years, magnetic resonance imaging (MRI) has become a cornerstone in evaluating anal canal and adjacent tissues due to its safeness, the three-dimensional and comprehensive approach, and the high soft-tissue resolution. Several diseases arising in the anal canal can be assessed through MRI performance, including congenital conditions, benign pathologies, and malignancies. Good knowledge of the normal anatomy and MRI technical protocols is, therefore, mandatory for appropriate anal pathology evaluation. Radiologists and clinicians should be familiar with the different clinical scenarios and the anatomy of the structures involved. This pictorial review presents an overview of the diseases affecting the anal canal and the surrounding structures evaluated with dedicated MRI protocol.

Evaluating postoperative anal fistula prognosis by diffusion-weighted MRI

PURPOSE

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Puborectalis Muscle Involvement on Magnetic Resonance Imaging in Complex Fistula: A New Perspective on Diagnosis and Treatment

PURPOSE

According to recent studies, magnetic resonance imaging (MRI) assessment of complex fistulas provides a significant benefit compared to fistulography, computed tomography, and ultrasonography. The aim of this study was to describe the accuracy of MRI and the importance of identifying puborectalis muscle involvement on MRI in patients with complex fistula.

METHODS

All patients who were clinically diagnosed with 'complex' or showed multiple fistula tracts underwent fistula MRI. Eligible patients were consecutive patients who underwent fistula MRI between September 2018 and September 2019 at our hospital.

RESULTS

A total of 83 patients (74 males, 9 females; 116 tracts) were included in this study. The sensitivity and specificity of MRI in diagnosing fistula tracts were 94.8% and 98.2%, respectively. The sensitivity and specificity in identifying internal opening were 93.9% and 97.3%, respectively. Of the 35 patients with puborectalis muscle involvement in the MRI, 31 images of suprasphincteric-type patients on the Park's classification were classified. The patients of puborectalis involvement were divided into 2 groups according to the surgical procedure that was performed. There were 12 sphincter-saving procedures and 19 sphincter division procedures performed. Recurrence was seen in 2 patients in the sphincter-saving procedure group, while no case was seen in the sphincter division procedure group. Five complications were found in the sphincter division procedure group, of which 2 reported incontinence.

CONCLUSION

Fistula MRI is a highly accurate examination for evaluating complex fistulas, and the puborectalis muscle involvement findings are very important for diagnosis and treatment.

MRI of perianal fistulas in Crohn's disease

Perianal fistulas represent one of the most critical complications of Crohn’s disease (CD). Management and treatment need a multidisciplinary approach with an accurate description of imaging findings.

Perirectal abscess with dysuria

Perirectal abscesses often occur in the dorsal portion of the perirectal tissues. We report a patient who presented with fever, pain on defecation, and dysuria. He was found to have a perirectal abscess in the anterior perineum pressing on the urethra. After emergency surgery to drain the abscess, the symptoms improved.

Perianal fistula mapping at 3 T: volumetric versus conventional MRI sequences

AIM

To evaluate volumetric contrast-enhanced three-dimensional T1-weighted (CE 3D T1) turbo spin-echo (TSE) with variable flip angle (SPACE), CE 3D T1 volumetric interpolated breath-hold examination (VIBE) sequences with conventional CE-two-dimensional (2D)-T1 and 2D-T2-weighted imaging (WI) sequences in assessing perianal fistulas.

METHODS AND MATERIALS

Twenty-three patients with perianal fistula were included in this prospective study and underwent pelvic magnetic resonance imaging (MRI) at 3 T including fat-supressed CE 3D T1 SPACE, CE 3D T1 VIBE, axial and coronal 2D-T1WI together with 2D-T2WI sequences in the axial and coronal planes. Acquisition times were recorded. Performance of each sequence was evaluated in terms of image quality, presence of artefacts, lesion conspicuity, fistula type, presence of abscess, visibility of internal orifice, and number of internal orifices. Results were compared with post-surgical findings defined as the reference standard.

RESULTS

Both CE 3D T1 VIBE and CE 3D T1 SPACE were the best sequences to determine fistula type and in terms of image quality, artefacts, and determining locations of internal orifices. The number of internal orifices was detected correctly in 23 (100%) patients for CE 3D T1 SPACE and CE 3D T1 VIBE sequences, in 17 (73.9%) patients on CE-T1WI, and in seven (30.4%) patients on 2D-T2WI. Lesion conspicuity was higher for CE 3D T1 SPACE and CE 3D T1 VIBE sequences compared to the 2D sequences (p<0.05). The overall acquisition time for each 3D sequence was shorter compared to the 2D sequences combined.

CONCLUSION

CE 3D T1 SPACE and CE 3D T1 VIBE sequences may outperform conventional 2D sequences in the evaluation of perianal fistulas in terms of visibility and number of internal orifices with a shorter scanning time.

Evaluating inflammatory activity in Crohn's disease by cross-sectional imaging techniques

The evaluation of inflammatory bowel activity in patients with Crohn’s disease has traditionally been a challenge, mainly because of the difficulty in gaining endoscopic access to the small bowel. Historically, barium-based contrast studies were the only option for the evaluation of inflammatory activity in Crohn’s disease. They were gradually replaced by cross-sectional imaging techniques, computed tomography enterography (CTE) and magnetic resonance enterography (MRE) now being the modalities of choice for such evaluations. Those two imaging methods have provided important information regarding intestinal wall involvement and extra-intestinal manifestations of Crohn’s disease, not only assessing lesion characteristics and complications but also quantifying inflammatory bowel activity. The objective of this article is to review the main technical aspects of CTE and MRE, together with their indications, contraindications, and limitations, as well as the CTE and MRE imaging characteristics of inflammatory activity in Crohn’s disease.