Observer agreement in single computerized tomography use for diagnosing paediatric head and neck malignancies at Uganda Cancer Institute.

Background: In the Ugandan setting, investigation for PHNM with CT uses a protocol with both unenhanced and contrast enhanced procedures hence doubling the ionizing radiation exposure. The purpose of this study was to determine the feasibility of single CT procedures in diagnosing PHNM.

Methods: This was a cross-sectional study using CT images from patients, aged fifteen years and below, investigated for head and neck malignancies at the Uganda Cancer Institute. Three radiologists, observers A, B and C, with 12, 5 and 2 years of experience, respectively, participated in the study. They independently reported contrast enhanced images (protocol A), unenhanced images (protocol B), then both unenhanced and contrast enhanced images (protocol C) in 2 months intervals. Inter- and intra- observer agreement was determined using Gwen's Agreement coefficient.

Results: Seventy-three CT scans of 36 boys and 37 girls, with a median age of 9 (3-13) years, were used. Intra-and inter-observer agreement on primary tumour location ranged from substantial to almost perfect with the highest intra-observer agreement observed when protocols A and C were compared. Inter-observer agreement for tumour calcifications was substantial for protocol A. Observers A and C demonstrated an almost perfect intra-observer agreement when protocols A and C were compared. There was a substantial inter-observer agreement on diagnosis for all protocols.

Conclusions: In our setting and examining a limited number of CT images, we demonstrated that contrast-enhanced CT scans provide sufficient information with no evidence of additional value of unenhanced images. Using contrast-enhanced images alone reduced the radiation exposure significantly.