Added value of abdominal cross-sectional imaging (CT or MRI) in staging of Wilms' tumours.

AIM: To assess the added information gained from computed tomography (CT) or magnetic resonance imaging (MRI) of the abdomen over abdominal ultrasound in children undergoing staging of Wilms' tumours.

MATERIALS AND METHOD: Fifty-two consecutive patients with histologically proven Wilms' tumours were identified. Each had an initial staging abdominal ultrasound followed by either a CT or MRI examination of the abdomen. Details including tumour size, site, and characteristics, presence of lymph nodes, local invasion, evidence of nephroblastomatosis, and any other relevant finding were gathered from the report of each ultrasound and CT or MRI. Each CT/MRI was then re-reviewed by a consultant paediatric radiologist and a paediatric radiology fellow. The difference in findings between the ultrasound and cross-sectional imaging were noted.

RESULTS: Twelve patients were excluded from the study because the CT/MRI was performed before the ultrasound, or imaging was incomplete. Twenty-six patients were female, 14 male. The ages ranged from 9 months to 10.8 years (mean 3.75 years). Twenty-one patients out of the remaining 40 had additional findings detected on the CT or MRI examination that had not been reported on the ultrasound. The most important additional findings included three patients with nephroblastomatosis and two with contralateral tumours. Other findings included two patients with tumour haemorrhage, four with abdominal lymph node enlargement, three with inferior vena cava (IVC)/renal vein thrombus, four with adjacent organ invasion, one patient where the origin of the abdominal tumour was confirmed as renal, and one patient where possible liver invasion was excluded.

CONCLUSION: In over half the patients, CT or MRI added additional information in the local staging of Wilms' tumours. Sole reliance on ultrasound for Wilms' staging risks missing significant abnormalities.