Semi-quantitative assessment of diffuse hepatic uptake seen in I-131 scans – an indicator of functioning thyroid tissue and disease burden in differentiated thyroid cancer

Prasanta K. PradhanEmail author View ORCID ID profile,
Suruchi Jain,
Madhusudhanan Ponnuswamy,
Amitabh Arya and
Manish Ora

Thyroid Research201912:4

https://doi.org/10.1186/s13044-019-0065-1

Received: 30 November 2018
Accepted: 12 April 2019
Published: 25 April 2019

Abstract

Background

To semi-quantitatively analyze liver uptake of I-131 in diagnostic and post-therapy scans by calculating hepatic to thigh ratios (HTR) and evaluate its clinical significance in management of differentiated thyroid cancer.

Method

Two hundred forty-nine patients were included in the study. Hepatic to thigh ratio (HTR) of counts were calculated for 249 diagnostic and 104 post-therapy scans. Patients were divided into six study groups based on their disease status:1-Serum thyroglobulin (serum Tg) negative (serum Tg ≤ 4 ng/dl) and scan negative; 2-Thyroid remnant only; 3-Thyroid remnant and lymph node metastasis; 4- Tg positive (serum Tg > 4 ng/dl) and scan negative; 5-Bone or/and lung metastasis, and 6-Only lymph node metastasis. Comparison of HTR between these groups was done using one-way ANOVA test. Correlation of HTR with serum Tg, serum thyroid stimulating hormone (TSH), anti-thyroglobulin antibody (ATg) titer and therapeutic dose of I-131 was also assessed.

Results

Comparison of HTR between different study groups (1 to 6) showed significant difference in HTR (p = .001). Study group 5 (bone or/and lung metastasis) showed significantly higher mean HTR compared to other groups (p = 0.001). There was only a weak correlation between serum Tg and HTR (r = 0.395). Dose of I-131 administered also had a weak correlation with HTR (r = 0.207).

Conclusion

HTR has good correlation with functional status of tumor cells, while it has weak correlation to therapeutic dose of I-131 administered and serum Tg. Increased HTR predicts significant disease burden in the form of distant bone and lung metastasis and may potentially be used as a second prognostic factor apart from serum Tg.