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Performance characteristics of magnetic resonance imaging without contrast agents or sedation in pediatric
Ryne A Didier1, Katharine L Hopkins2, Fergus V Coakley2
1Department of Diagnostic Radiology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR, 97239, USA. ryne.didier@childrens.harvard.edu.
Background:
Magnetic resonance imaging (MRI) has emerged as a promising modality for evaluating pediatric appendicitis. However optimal imaging protocols, including roles of contrast agents and sedation, have not been established and diagnostic criteria have not been fully evaluated.
Objective:
To investigate performance characteristics of rapid MRI without contrast agents or sedation in the diagnosis of pediatric appendicitis.
Materials And Methods:
We included patients ages 4-18 years with suspicion of appendicitis who underwent rapid MRI between October 2013 and March 2015 without contrast agent or sedation. After two-radiologist review, we determined performance characteristics of individual diagnostic criteria and aggregate diagnostic criteria by comparing MRI results to clinical outcomes. We used receiver operating characteristic (ROC) curves to determine cut-points for appendiceal diameter and wall thickness for optimization of predictive power, and we calculated area under the curve (AUC) as a measure of test accuracy.
Results:
Ninety-eight MRI examinations were performed in 97 subjects. Overall, MRI had a 94% sensitivity, 95% specificity, 91% positive predictive value and 97% negative predictive value. Optimal cut-points for appendiceal diameter and wall thickness were ≥7 mm and ≥2 mm, respectively. Independently, those cut-points produced sensitivities of 91% and 84% and specificities of 84% and 43%. Presence of intraluminal fluid (30/33) or localized periappendiceal fluid (32/33) showed a significant association with acute appendicitis (P<0.01), with sensitivities of 91% and 97% and specificities of 60% and 50%. For examinations in which the appendix was not identified by one or both reviewers (23/98), the clinical outcome was negative.
Conclusion:
Rapid MRI without contrast agents or sedation is accurate for diagnosis of pediatric appendicitis when multiple diagnostic criteria are considered in aggregate. Individual diagnostic criteria including optimized cut-points of ≥7 mm for diameter and ≥2 mm for wall thickness demonstrate high sensitivities but relatively low specificities. Nonvisualization of the appendix favors a negative diagnosis.
Insights
Rapid magnetic resonance imaging (MRI) without contrast or sedation accurately diagnoses pediatric appendicitis. Combining multiple imaging criteria improves diagnostic accuracy for this common condition in children.
Area of Science:
- Pediatric Radiology
- Diagnostic Imaging
- Gastrointestinal Imaging
Background:
- Magnetic resonance imaging (MRI) is a promising tool for pediatric appendicitis diagnosis.
- Optimal MRI protocols and diagnostic criteria for pediatric appendicitis remain unestablished.
Purpose of the Study:
- To evaluate the diagnostic performance of rapid MRI without contrast agents or sedation for pediatric appendicitis.
- To establish optimal imaging criteria for accurate diagnosis.
Main Methods:
- Retrospective analysis of 98 rapid MRI scans (ages 4-18) performed without contrast or sedation.
- Two-radiologist review to assess diagnostic criteria and compare with clinical outcomes.
- Receiver operating characteristic (ROC) curve analysis to determine optimal cut-points for appendiceal diameter and wall thickness.
Main Results:
- Overall MRI accuracy: 94% sensitivity, 95% specificity.
- Optimal cut-points: appendiceal diameter ≥7 mm (91% sensitivity, 84% specificity) and wall thickness ≥2 mm (84% sensitivity, 43% specificity).
- Presence of intraluminal or periappendiceal fluid significantly associated with appendicitis; nonvisualization of appendix indicated a negative diagnosis.
Conclusions:
- Rapid MRI without contrast or sedation is accurate for diagnosing pediatric appendicitis when multiple criteria are used.
- Optimized individual criteria show high sensitivity but variable specificity.
- Nonvisualization of the appendix strongly suggests a negative diagnosis.
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