Re-exploration of Radio-iodine Diffuse Hepatic Uptake as Early Prognostic Indicator in Differentiated Thyroid Carcinoma.

Background: The aim of this study was to explore the potential early prognostic value of radio-iodine diffuse hepatic uptake (DHU) in post-ablative whole body iodine scans (PAWBISs) of patients with low/intermediate risk differentiated thyroid cancer (DTC) and no evidence of disease. Patients and Methods: A total of newly diagnosed 100 patients with pathologically proven DCT presented in the department of nuclear medicine and radiation oncology, Cairo University were prospectively included; age (18-75-year-old); They were followed for a period of 30.9 ± 12.4months. Grades of hepatic and thyroid bed uptake PAWBISs were classified from 0 to 3 by visual assessment. Endpoints were no evidence of disease (NED), the persistence of disease or disease recurrence till the end of thefollow-up period. Comparison of numerical variables between the study groups was done using Chi-square (c2) test. Exact test was used instead when the expected frequency is less than 5. Comparison was done between the different factors by Log-rank method using Cox-Mantel equation. Cox multivariate regression was used to determine the preferential effect of important variables. p values less than 0.05 was considered statistically significant. Results: DHU was observed in 87 PAWBISs; grade 1 ‘mild’ uptake was observed in 28, grade 2 ‘moderate’ in 46, grade 3 ‘marked’ in 13 PAWBISs. Analysis of the different grades of DHU in the low and high dose groups of patients showed significant association with the outcome (p 0.001).Univariante analysis showed that the grade of DHU (p 0.005) as well as the patient gender, age, primary tumor size and cervical LN status are statistically significant predictors of the outcome. Multivariate analysis also showed that the grade of DHU, patient gender and tumor multiplicity and are the only independent prognostic factors with p values 0.048, 0.042, 0.009 respectively. Conclusion: more intense visualization of DHU on PAWBIS is considered as an independent prognostic factor associated with a better outcome in low/intermediate risk DTC patients than its faint visualization which may be related to ineffective thyroid cells destruction in the latter.