Observer agreement in single computerized tomography use for diagnosing paediatric head and neck malignancies at Uganda Cancer Institute.
Mugisha, Alex Mwesigwa
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Introduction Five percent of all childhood malignancies are of the head and neck and this prevalence is on the rise. With an increase in these malignancies, there is increased use of computerized tomography (CT), a source of ionizing radiation, for diagnosis, staging, treatment and treatment response assessment. Children below 12 years are at a risk of up to ten times more for radiation induced secondary malignancies. Currently, in our setting, investigation for head and neck malignancies with computerized tomography uses a protocol with both unenhanced and contrast enhanced CT procedures. However, no study has been done to assess the possibility of using only one procedure, without loss of diagnostic information, as a way of reducing radiation exposure during the CT investigations. General Objective To determine the observer agreement between paediatric head and neck malignancy findings of single CT procedures and double CT procedures for children under fifteen years at the Uganda Cancer Institute (UCI). Methods This was a cross-sectional study using computerized tomography images from patients below the age of fifteen being investigated for head and neck malignancies at the Uganda Cancer Institute (UCI). Three radiologists independently reported the contrast enhanced images (protocol A), then read the unenhanced images (protocol B) after two months and then read both (Protocol C) after two months. A structured template from the Radiology Society of North America (RSNA) was used for documenting the findings and diagnosis. Inter - and intra - observer agreement of the findings between the single and double CT procedures was compared using Gwet’s Agreement coefficient. Results A total of seventy-three (73) CT scans were included in this study. The patients were 36 (49.3%) boys and 37 (50.7%) girls with a median age of 9(3-13) years. Inter-observer agreement results for; primary tumour location was 0.71, 0.74 and 0.84 for protocols A, B and C respectively, tumour calcifications were 0.70, 0.83 and 0.84 for protocols A, B and C respectively, lymphadenopathy were 0.47, 0.69 and 0.79 for protocols A, B and C respectively and for diagnosis were 0.61, 0.68 and 0.68 for protocols A, B and C respectively. When protocols A and C were compared, the intra-observer agreements for primary tumour location, tumour calcifications, lymphadenopathy and diagnosis were: observer A: 0.71, 0.58, 0.82 and 0.68 respectively; observer B: 0.80, 0.73, 0.37 and 0.57 respectively; and for observer C: 0.87, 0.81, 1 and 0.90 respectively. When protocols B and C were compared, the intra-observer agreements for primary tumour location, tumour calcifications, lymphadenopathy and diagnosis were: observer A: 0.73, 0.75, 0.65 and 0.60 respectively; observer B: 0.67, 0.71, 0.51 and 0.58 respectively; and for observer C: 0.71, 0.61, 0.72 and 1 respectively. Conclusions From this study, it can be concluded that the use of double CT procedures for diagnosis of paediatric head and neck malignancies for children aged 15 years and below does not show a significant advantage over the use of contrast enhanced single CT only procedures. Contrast enhanced CT only procedures for paediatric head and neck cancers were sufficient in identifying presence of tumor calcifications. Patients with iodine contrast allergies and no access to magnetic resonance imaging can benefit from unenhanced CT procedures which provides information on primary tumour location, presence of calcifications, presence of lymphadenopathy and a diagnosis. Building upon this study, more multi-center studies with use of contrast enhanced CT only procedures in diagnosing paediatric head and neck malignancies are recommended to further validate the generalizability of the findings from this study.