Diagnosis of vascular rings and slings using an interleaved 3D double-slab FISP MR angiography technique

Background: Congenital upper airway obstruction and dysphagia may be caused by vascular rings and slings. Often, invasive and radiation-dependent diagnostic procedures are needed to clarify the diagnosis. Objective: To evaluate the diagnostic utility of high-resolution, free-breathing three-dimensional double-slab fast imaging with steady precession magnetic resonance angiography (3D FISP MRA) in infants and children with respiratory upper airway obstruction and/or dysphagia for detection or exclusion of vascular rings and slings. Materials and methods: Eleven patients (median age 1.3 years; range 5.1 months to 15.8 years) were investigated prospectively with 3D FISP MRA and spin-echo techniques. Additional diagnostic data were available from surgery (n = 7), cardiac catheterization (n = 5), CT (n = 2), barium swallow (n = 3) and bronchoscopy/oesophagoscopy (n = 4). Results: In one case, diagnosis was missed with low-resolution spin-echo sequences, but high-resolution 3D FISP MRA revealed a double aortic arch. 3D FISP MRA accurately found (n = 8) or excluded (n = 3) vascular rings or slings in all patients. Using a five-level grading system for 3D FISP MRA image quality (1=non-diagnostic; 5=excellent), the mean grade was 4.3 ± 0.7 with no significant grade difference between two independent observers (P = 0.81). Conclusions: High-resolution 3D FISP MRA accurately defined or excluded vascular rings and slings in patients with respiratory symptoms and/or dysphagia. This technique may provide a non-invasive, radiation-free alternative without contrast agents for diagnosis of vascular rings and slings in free-breathing infants and children.