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A systematic review and meta-analysis of the diagnostic test accuracy of diffusion weighted imaging and apparent
S Inggriani1, D L Rahmawati2, G S Octavius2
1Abdominal Imaging Division, Department of Radiology, Faculty of Universitas Pelita Harapan, Tangerang, Indonesia; Head of Radiology Department of Medistra Hospital, Jakarta, Indonesia.
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.
Insights
Apparent diffusion coefficient (ADC) alone is insufficient for differentiating active from inactive perianal fistulas. Combining T2-weighted imaging (T2WI) with diffusion-weighted imaging (DWI) offers superior diagnostic accuracy for perianal fistula assessment.
Area of Science:
- Radiology
- Gastroenterology
- Medical Imaging
Background:
- Perianal fistulas require accurate differentiation between active and inactive states for effective management.
- Magnetic Resonance Imaging (MRI) techniques, including apparent diffusion coefficient (ADC) and diffusion-weighted imaging (DWI), are explored for this diagnostic challenge.
Purpose of the Study:
- To systematically review and meta-analyze the diagnostic accuracy of MRI-based ADC and DWI in distinguishing active from inactive perianal fistulas.
- To compare the performance of different MRI sequences for perianal fistula evaluation.
Main Methods:
- Systematic review and meta-analysis of studies evaluating MRI for perianal fistulas.
- Inclusion of five major scientific databases and meta-analysis using STATA software.
- Analysis of diagnostic performance metrics including sensitivity, specificity, and AUC.
Main Results:
- Six studies reported ADC values for active vs. inactive fistulas, yielding a pooled sensitivity of 83%, specificity of 75%, and AUC of 0.85.
- The T2WI + DWI sequence demonstrated exceptional diagnostic accuracy with a pooled sensitivity of 99%, specificity of 97%, and AUC of 1.
- Pooled ADC cut-offs ranged from 1.105 to 1.109 × 10⁻³ mm²/s.
Conclusions:
- Apparent diffusion coefficient (ADC) alone is inadequate for reliably distinguishing active from inactive perianal fistulas.
- T2WI combined with DWI offers superior diagnostic performance compared to contrast-enhanced T1WI for non-invasive perianal fistula evaluation.
- Further research is warranted due to moderate to high risk of bias and heterogeneity in existing studies.
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