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Diagnostic Accuracy of Short Tau Inversion Recovery as a Limited Protocol for Diagnosing Perianal Fistula
Naila Jabeen1, Ruby Qureshi1, Amjad Sattar1
1Radiology, Dow University of Health Sciences, Karachi, PAK.
Abstract:
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 1st February 2018 to 1st 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.
Insights
Short tau inversion recovery (STIR) MRI is highly accurate for diagnosing perianal fistulas. This limited MRI protocol offers a cost-effective solution for improving patient care in developing countries.
Area of Science:
- Radiology
- Gastroenterology
- Surgical Imaging
Background:
- Perianal fistula diagnosis relies on imaging modalities like MRI and endoanal ultrasound.
- Endoanal ultrasound is cost-effective but operator-dependent.
- MRI provides detailed anatomy and fistula identification but can be resource-intensive.
Purpose of the Study:
- To evaluate the diagnostic accuracy of a limited MRI pelvis protocol using short tau inversion recovery (STIR) sequences.
- To determine the cost-effectiveness and accuracy of STIR MRI for perianal fistula diagnosis in a developing country context.
Main Methods:
- Retrospective review of 150 MRI pelvis scans performed between February 1, 2018, and July 1, 2018.
- Comparison of interpretations by a radiologist viewing the complete MRI pelvis versus another radiologist viewing only axial and coronal STIR sequences.
- Surgical findings served as the gold standard for diagnosis.
Main Results:
- The STIR-limited protocol identified fistulae in 83.3% of patients, compared to 79.3% on surgery.
- Sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of STIR were 96.6%, 67.7%, 92.0%, 84.0%, and 90.6%, respectively.
- The STIR protocol demonstrated high diagnostic accuracy (90.6%) and sensitivity (96.6%) for perianal fistula detection.
Conclusions:
- Short tau inversion recovery (STIR) sequences provide high sensitivity and diagnostic accuracy for perianal fistulas.
- A limited STIR MRI protocol is a valuable, cost-effective tool for diagnosing perianal fistulas, especially in developing nations.
- Further research is recommended to assess STIR's capability in identifying internal fistula openings to enhance patient management.
