Evaluating postoperative anal fistula prognosis by diffusion-weighted MRI

A systematic review and meta-analysis of the diagnostic test accuracy of diffusion weighted imaging and apparent diffusion coefficient in differentiating active from inactive perianal fistula

INTRODUCTION

This systematic review and meta-analysis evaluated the diagnostic accuracy of MRI-based apparent diffusion coefficient (ADC) and diffusion-weighted imaging (DWI) for differentiating active from inactive perianal fistulas.

METHODS

The protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO) (CRD42024596604). The review included five databases (MEDLINE, Cochrane Library, PubMed, Science Direct, and Google Scholar). Meta-analyses were performed on studies reporting ADC values and other sequences using STATA software with the "Midas" command.

RESULTS

Of 21 studies included in the review, 12 were meta-analyzed, encompassing 1007 patients (77.5 % male) with 1092 fistulas and 321 abscesses. Six studies reported ADC values for active vs. inactive fistulas, with a pooled sensitivity of 83 % (95%CI 68-92), specificity of 75 % (95%CI 60-85), and AUC of 0.85 (95%CI 0.81-0.87). Pooled ADC cut-offs ranged from 1.105 to 1.109 × 10⁻³ mm2/s. The T2WI + DWI sequence demonstrated the highest diagnostic accuracy, with a pooled sensitivity of 99 % (95%CI 90-100), specificity of 97 % (95%CI 79-100), and an AUC of 1.

CONCLUSION

ADC alone is inadequate for reliably distinguishing active from inactive fistulas. T2WI combined with DWI offers superior diagnostic performance, surpassing contrast-enhanced T1WI, and is promising for non-invasive evaluation of perianal fistulas. However, several limitations, such as moderate to high risk of bias and heterogeneity, may bias this conclusion.

IMPLICATIONS FOR PRACTICE

T2WI + DWI could become the standard for assessing perianal fistulas, avoiding contrast agents, and benefiting patients contraindicated for Gadolinium-based contrast media. Variability and potential bias across studies warrant further research.

Recent advances in the diagnosis and treatment of complex anal fistula

Anal fistula can be a challenging condition to manage, with complex fistulas presenting even greater difficulties. The primary concerns in treating this condition are a risk of damage to the anal sphincters, which can compromise fecal continence, and refractoriness to treatment, as evidenced by a high recurrence rate. Furthermore, the treatment of complex anal fistula involves several additional challenges. Satisfactory solutions to many of these obstacles remain elusive, and no consensus has been established regarding the available treatment options. In summary, complex anal fistula has no established gold-standard treatment, and the quest for effective therapies continues. This review discusses and highlights groundbreaking advances in the management of complex anal fistula over the past decade.

An applicability study of rapid artificial intelligence-assisted compressed sensing (ACS) in anal fistula magnetic resonance imaging

Objective

To evaluate the applicability of artificial intelligence-assisted compressed sensing (ACS) to anal fistula magnetic resonance imaging (MRI).

Methods

51 patients were included in this study and underwent T2-weighted sequence of MRI examinations both with ACS and without ACS technology in a 3.0 T MR scanner. Subjective image quality scores, and objective image quality-related metrics including scanning time, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR), were evaluated and statistically compared between the images collected with and without ACS.

Results

No significant difference in the subjective image quality of lesion conspicuity was observed between the two groups. However, ACS MRI decreased the acquisition time with regard to control group (74.00 s vs. 156.00 s). Besides, SNR of perianal and muscle in the ACS group was significantly higher than that of the control group (164.07 ± 33.35 vs 130.81 ± 29.10, p < 0.001; 109.87 ± 22.01 vs 87.61 ± 17.95, p < 0.001; respectively). The CNR was significantly higher in the ACS group than in the control group (54.02 ± 23.98 vs 43.20 ± 21.00; p < 0.001). Moreover, the accuracy rate of the ACS groups in evaluating the direction and internal opening of the fistula was 88.89 %, exactly the same as that of the control group.

Conclusion

We demonstrated the applicability of using ACS to accelerate MR of anal fistulas with improved SNR and CNR. Meanwhile, the accuracy rates of the ACS group and the control were equivalent in evaluating the direction and internal opening of the fistula, based on the results of surgical exploration.

Two-finger digital rectal examination for the diagnosis of anal fistula: protocol for a randomized controlled trial

BACKGROUND

Anal fistula is an anorectal infectious disease caused by a perianal abscess or perianal disease. Accurate anorectal examinations are of great significance. The two-finger digital rectal examination (TF-DRE) has been used in clinical practice, with a lack of comprehensive research on the value of the TF-DRE in the diagnosis of anal fistula. This study will compare the difference in the diagnostic value of the TF-DRE, traditional digital rectal examination (DRE), and anorectal ultrasonography in the diagnosis of anal fistula.

METHODS

For patients who meet the inclusion criteria, a TF-DRE will be performed to explore the number and location of the external and internal orifices, the number of fistulas, and the relationship between the fistula and the perianal sphincter. A DRE and anorectal ultrasonography will also be performed, and the same data will be recorded. To make a comparison, the final diagnosis results of the clinicians during the operation will be taken as the gold standard, the accuracy of the TF-DRE in diagnosing anal fistula will be calculated, and the significance of the TF-DRE in the preoperative diagnosis of anal fistula will be studied and analyzed. All the statistical results will be analyzed using SPSS22.0 (IBM, USA), and a P value <0.05 will be considered statistically significant.

DISCUSSION

The research protocol details the advantages of the TF-DRE compared to the DRE and anorectal ultrasonography in the diagnosis of anal fistula. This study will provide clinical evidence of the diagnostic value of the TF-DRE in the diagnosis of anal fistula. Currently, there is a lack of high-quality research using scientific methods on this innovative anorectal examination method. This study will provide rigorously designed clinical evidence on the TF-DRE.

REGISTRATION

Chinese Clinical Trials Registry ChiCTR2100045450.

Predictors of outcome in cryptoglandular anal fistula according to magnetic resonance imaging: A systematic review

Background and Aims

Anal fistula (AF) with cryptoglandular origin tends to recur, and multiple risk factors are implicated. Recently, some magnetic resonance imaging (MRI) findings with predictive value for disease outcomes have been proposed. These intrinsic anatomic features include those of the AF and its surrounding structures. This study aims to clarify the prognostic role of MRI in AF.

Methods

We performed a systematic search of PubMed, Embase, and EBSCO databases. Two independent reviewers conducted the search and screened the articles. We selected studies that used MRI to assess AF and reported its relationship to disease outcome. We extracted data regarding the study design, type of intervention, outcome, MRI-measured items, and their significance.

Results

Out of 1230 retrieved articles, 18 were eligible for final inclusion, and a total of 4026 patients were enrolled in the selected studies. For preoperative MRI, the significant items affecting the outcome were the length of the fistula, horseshoe type, presence of multiple tracts, supralevator extension, and apparent diffusion coefficient (ADC) value. Other studies investigated the healing process using postoperative MRI.

Conclusion

This review found that MRI can be useful in the management of AF, both preoperatively and postoperatively. Factors, such as fistula length, horseshoe type, presence of multiple tracts, supralevator extension, and ADC value were found to be significantly associated with treatment outcomes. The presence of the fistula tract and the development of new abscesses on postoperative MRI was found to hinder the healing process. Further studies are needed to confirm these findings.

Three-dimensional pelvic ultrasound is a practical tool for the assessment of anal fistula

OBJECTIVE

This study aims to investigate the diagnostic value of three-dimensional pelvic ultrasound in the preoperative assessment of anal fistula compared with findings of MRI and surgery.

METHODS

A total of 67 patients (62 males) with suspected anal fistula were analyzed retrospectively. Preoperative three-dimensional pelvic ultrasound and magnetic resonance imaging were performed in all patients. The number of internal openings and the type of fistula were recorded. The accuracy of three-dimensional pelvic ultrasound was determined by comparing these parameters with surgical outcomes.

RESULTS

At surgery, 5 (6%) were extrasphincteric, 10 (12%) were suprasphincteric, 11 (14%) were intersphincteric, and 55 (68%) were transsphincteric. There was no significant difference in the accuracy of pelvic 3D US and MRI, based on internal openings (97.92%, 94.79%), anal fistulas (97.01%, 94.03%), and those under Parks classification (97.53%, 93.83%).

CONCLUSION

Three-dimensional pelvic ultrasound is a reproducible and accurate method for determining the type of fistula and detecting internal openings and anal fistulas.

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

Purpose

To retrospectively assess the accuracy of magnetic resonance imaging (MRI) in defining dentate line in anal fistula.

Materials and methods

Seventy patients with anal fistulas were assessed by dynamic contrast-enhanced MRI. The distance from the dentate line to the anal verge for all patients was measured by MRI. To mitigate interference, 35 patients with anal fistulas whose internal openings were located on the dentate line were excluded from this study. Two observers independently judged the positional relationship between the internal opening and the MRI-defined dentate line, and compared with the results observed by surgeon to assess the accuracy.

Results

The distance between the MRI-defined dentate line and the anal verge depended on the location of the internal opening and the morphology of the anal canal mucosa. The distance based on the location the internal opening and the morphology of the anal canal mucosa was 18.2 ± 8.1 mm and 20.0 ± 5.3 mm on oblique coronal T2WI, respectively. Compared with the results observed by the surgeon, the accuracy of evaluating the positional relationship between the internal opening and the dentate line from the morphology of the anal canal mucosa on MRI exceeded 89.9%. Taking 18.2–20.0 mm as the distance between the dentate line and the anal verge on the MRI image, the accuracy of evaluating the relationship between the position of the internal opening and the dentate line was over 85.7%. Considering both the dentate line and the anal canal mucosa, the accuracy of evaluating the relationship between the internal opening and the dentate line was over 91.5%. The results of MRI-defined dentate line were in good agreement with the results of intraoperative surgeon evaluation, and the κ values were 0.70, 0.63, and 0.78, respectively.

Conclusion

MRI has high accuracy in defining the dentate line in anal fistulas.

Telemedicine in Surgical Care in Low- and Middle-Income Countries: A Scoping Review

BACKGROUND

Access to timely and quality surgical care is limited in low- and middle-income countries (LMICs). Telemedicine, defined as the remote provision of health care using information, communication and telecommunication platforms have the potential to address some of the barriers to surgical care. However, synthesis of evidence on telemedicine use in surgical care in LMICs is lacking.

AIM

To describe the current state of evidence on the use and distribution of telemedicine for surgical care in LMICs.

METHODS

This was a scoping review of published and relevant grey literature on telemedicine use for surgical care in LMICs, following the PRISMA extension for scoping reviews guideline. PubMed-Medline, Web of Science, Scopus and African Journals Online databases were searched using a comprehensive search strategy from 1 January 2010 to 28 February 2021.

RESULTS

A total of 178 articles from 53 (38.7%) LMICs across 11 surgical specialties were included. The number of published articles increased from 2 in 2010 to 44 in 2020. The highest number of studies was from the World Health Organization Western Pacific region (n = 73; 41.0%) and of these, most were from China (n = 69; 94.5%). The most common telemedicine platforms used were telephone call (n = 71, 39.9%), video chat (n = 42, 23.6%) and WhatsApp/WeChat (n = 31, 17.4%). Telemedicine was mostly used for post-operative follow-up (n = 71, 39.9%), patient education (n = 32, 18.0%), provider training (n = 28, 15.7%) and provider-provider consultation (n = 16, 9.0%). Less than a third (n = 51, 29.1%) of the studies used a randomised controlled trial design, and only 23 (12.9%) reported effects on clinical outcomes.

CONCLUSION

Telemedicine use for surgical care is emerging in LMICs, especially for post-operative visits. Basic platforms such as telephone calls and 2-way texting were successfully used for post-operative follow-up and education. In addition, file sharing and video chatting options were added when a physical assessment was required. Telephone calls and 2-way texting platforms should be leveraged to reduce loss to follow-up of surgical patients in LMICs and their use for pre-operative visits should be further explored. Despite these telemedicine potentials, there remains an uneven adoption across several LMICs. Also, up to two-thirds of the studies were of low-to-moderate quality with only a few focusing on clinical effectiveness. There is a need to further adopt, develop, and validate telemedicine use for surgical care in LMICs, particularly its impact on clinical outcomes.

Guidelines to diagnose and treat peri-levator high-5 anal fistulas: Supralevator, suprasphincteric, extrasphincteric, high outersphincteric, and high intrarectal fistulas

Supralevator, suprasphincteric, extrasphincteric, and high intrarectal fistulas (high fistulas in muscle layers of the rectal wall) are well-known high anal fistulas which are considered the most complex and extremely challenging fistulas to manage. Magnetic resonance imaging has brought more clarity to the pathophysiology of these fistulas. Along with these fistulas, a new type of complex fistula in high outersphincteric space, a fistula at the roof of ischiorectal fossa inside the levator ani muscle (RIFIL), has been described. The diagnosis, management, and prognosis of RIFIL fistulas is reported to be even worse than supralevator and suprasphincteric fistulas. There is a lot of confusion regarding the anatomy, diagnosis, and management of these five types of fistulas. The main reason for this is the paucity of literature about these fistulas. The common feature of all these fistulas is their complete involvement of the external anal sphincter. Therefore, fistulotomy, the simplest and most commonly performed procedure, is practically ruled out in these fistulas and a sphincter-saving procedure needs to be performed. Recent advances have provided new insights into the anatomy, radiological modalities, diagnosis, and management of these five types of high fistulas. These have been discussed and guidelines formulated for the diagnosis and treatment of these fistulas for the first time in this paper.

Guidelines on postoperative magnetic resonance imaging in patients operated for cryptoglandular anal fistula: Experience from 2404 scans

Magnetic resonance imaging (MRI) is considered the gold standard for the evaluation of anal fistulas. There is sufficient literature available outlining the interpretation of fistula MRI before performing surgery. However, the interpretation of MRI becomes quite challenging in the postoperative period after the surgery of fistula has been undertaken. Incidentally, there are scarce data and no set guidelines regarding analysis of fistula MRI in the postoperative period. In this article, we discuss the challenges faced while interpreting the postoperative MRI, the timing of the postoperative MRI, the utility of MRI in the postoperative period for the management of anal fistulas, the importance of the active involvement and experience of the treating clinician in interpreting MRI scans, and the latest advancements in the field.

Role of MRI to confirm healing in complex high cryptoglandular anal fistulas: long-term follow-up of 151 cases

AIM

Complex fistula-in-ano can recur even after complete clinical healing has occurred. 'Radiological healing' of fistula on MRI correlates well with long-term healing rates but no study has yet objectively quantified this. The aim of this study was to assess the accuracy of anal fistula healing as documented on MRI and to correlate it with long-term healing as evidenced on long-term follow-up.

METHODS

Patients with clinically healed anal fistulas who also had radiological healing checked by postoperative MRI were included in the study.

RESULTS

Three hundred and twenty-five patients operated for high complex fistula-in-ano were followed up for 14-68 months (median 38 months). Postoperative MRI was done to assess radiological healing of the fistula in 151 patients, and they were included in the study. The mean age was 39.4 ± 10.5 years (116 men). Five patients were lost to follow-up. The fistulas did not heal radiologically (on MRI) in 20 patients and recurred in all these patients. The fistulas healed radiologically (on MRI) in 126 patients. On long-term follow-up, 124/126 patients remained healed while 2/126 had a recurrence. In the first patient, the fistula recurred 40 months after complete radiological healing. In the second patient, the fistula recurred 10 months after complete radiological healing but pus from the fistula tested positive for tuberculosis (by real-time polymerase chain reaction) and he was excluded from the analysis. Thus, there was only one (1/125) recurrence on long-term follow-up.

CONCLUSIONS

Radiological healing on MRI correlates well with long-term healing in complex fistula-in-ano.