1052 Pediatr Nephrol (2010) 25:1049–1056 Fig. 2 An 11-year-old boy with hypertension. a Contrast-enhanced magnetic resonance angiography (coronal maximum intensity projec- tion image) shows stenosis of the left renal artery (white arrow) but also suggests stenosis of the right (green arrow). b Angiogram of left kidney confirms a tight stenosis of the left main renal artery (arrow). c The right renal artery is normal specifically to show arterial anatomy [28]. CTA offers better spatial resolution than does MRA, but at the price of the patient’s exposure to ionising radiation. Careful atten- tion to technique is essential if the best quality images are to be obtained [28]. The three-dimensional dataset obtained can be manipulated and reviewed as multiplanar two- dimensional slices, maximum intensity projections, or as two-dimensional volume-rendered projections (Fig. 3). A recent study investigated 21 adult patients to identify how well CTA could show main renal arteries, accessory arteries and renal artery FMD [29]. CTA was able to identify all 42 main renal arteries, all 100 accessory arteries and all 40 FMD lesions. Similar results have been found in other studies, with 90–94% sensitivity and 62–97% specificity of CTA [14, 16, 30]. The authors of the large Dutch study mentioned above also included CTA in their evaluation, where images were evaluated by two panels of three investigators [25]. A total of 356 patients was examined by all three modalities (CTA, MRA and DSA). Twenty percent of the patients were judged to have clinically relevant RAS. The inter-observer agreement was only moderate (κ-values 0.59–0.64). The sensitivity for CTA in the detection of clinically relevant renal stenosis was 64% (95% CI 55–73%), and the specificity was 92% (95% CI 90–95%). A retrospective study of 24 children with the suggestion of RVD found RAS in five children, with CTA able to detect four of these [31]. In our clinical experience we find that CTA provides beautiful images of abdominal arteries. This is particularly true in children with mid-aortic syndrome (MAS) and other lesions affecting the large vessels. The ability of CTA to exclude clinically important lesions of small arteries is currently unproven, and, until this is demonstrated, CTA will not be widely applicable to children with suggested RVH. Sedation is often not required, but CTA, like DSA, requires the patient’s exposure to ionising radiation, and this is a particularly important consideration in its use for children.