Purpose or Case Report: Renal artery stenosis (RAS) is an important cause of hypertension in children. When suspected, imaging options include Doppler US, CTA and MRA. However, conventional angiography remains the gold standard. We investigate the accuracy and inter-reader reliability of CTA in children with suspected renal artery stenosis.
Methods & Materials: This is an IRB-approved retrospective study that included all patients who underwent DSA for suspected RAS with a CTA within 6 months prior to a DSA between 2008 and 2019. Basic demographics were retrieved from the electronic medical records. Each CTA was reviewed by 2 pediatric radiologists, blinded to clinical data and other imaging studies, to determine the presence of stenosis at the main and/or segmental renal artery. Angiograms were performed by a pediatric interventional radiologist with over 20-year experience, whose reports were used as standard reference for diagnosis of RAS. The sensitivity, specificity, and accuracy were calculated. Kappa statistics was performed to assess inter-reader agreement. Agreement was categorized as follows: less than 0.20, slight agreement; 0.21–0.40, fair agreement; 0.41–0.60, moderate agreement; 0.61–0.80, substantial agreement; and greater than 0.81, almost perfect agreement.
Results:
Seventy-four renal assessments of 37 patients were included. Mean patient age was 9.6 years (range, 1-21). The overall prevalence of RAS was 62.1% (n=23/37).
Six patients had a pre-existing diagnosis, 2 patients with neurofibromatosis type1, 2 patients with William syndrome and 2 patients with fibromuscular dysplasia. At the patient level, the diagnostic performance of CTA was: sensitivity 84.8% (95%CI: 71.1-93.7%), specificity 78.6% (95%CI: 59.1-91.7%), accuracy 82.4% (95%CI: 71.8-90.3%). The inter-observer agreement was almost perfect (k=0.83). At the main renal artery level, the sensitivity was 78.6% (95%CI: 65.6-88.4%), specificity 92.4% (95%CI: 85.0-96.9%), accuracy 87.2% (95%CI: 80.7-92.1%). The inter-observer agreement was moderate (k=0.73). At the segmental renal artery level, the sensitivity was 71.4% (95%CI: 0.2-33.9%), specificity 97.8% (95%CI: 93.6-99.5%), accuracy 89.2% (95%CI: 83.0-93.7%).
Conclusions: CTA has moderate to high sensitivity and high specificity at the patient and main renal artery levels. However, it performs moderately at the segmental level. Therefore, it offers good quality as a screening and pre-procedure planning modality but cannot substitute DSA in patients with high suspicion of RAS.