The goal of this study was to evaluate the incremental value of unenhanced phase in the initial evaluation of retroperitoneal tumors in children by comparison with an enhanced phase alone using computed tomography (CT).

A total of 53 patients (26 girls, 27 boys) with a total of 53 tumors who had CT examination of the abdomen and pelvis for the initial assessment of retroperitoneal tumor were retrospectively included. All CT examinations were obtained with an unenhanced set of CT images and a set of CT images obtained after intravenous administration of iodinated contrast material. One junior and one senior radiologist independently evaluated the two sets in two separate reading sessions. CT images were analyzed for tumor calcifications, tumor location, vascular encasement, local invasion and tumor content.

Calcifications were present in 24/53 tumors (45%). On the enhanced set, the senior radiologist was able to detect calcifications in 22/24 tumors (92%) and the junior radiologist in 20/24 tumors (83%), yielding sensitivities of 92% and 83%, and specificities of 96.5% and 100%, respectively. Inter-observer agreement was excellent (Kappa=0.89). Tumor location was correctly determined by the senior radiologist in 53/53 tumors (100%) and 37/53 tumors (70%) by the junior radiologist. Using the unenhanced set, the senior radiologist was able to assess vascular encasement in 26/53 tumors (49%) against 21/53 (39%) for the junior radiologist. For tumor content, agreement between the enhanced and combined unenhanced and enhanced CT was 77% for both radiologists.

Enhanced CT performs as well as unenhanced CT for evidencing calcifications and is therefore sufficient for the initial assessment of retroperitoneal tumor in children.