Chronic thyroiditis in patients with advanced breast carcinoma: metabolic and morphologic changes on PET-CT.
OBJECTIVE
To investigate clinical implications of FDG uptake in the thyroid glands in patients with advanced breast carcinoma by comparing metabolic and morphologic patterns on positron emission tomography (PET)/computed tomography (CT).


METHODS
The institutional review board waived the requirement for informed consent. A retrospective analysis was performed in 146 women (mean age 54 years) with advanced breast carcinoma who received systemic treatment. All patients underwent PET-CT before and after treatment. All PET-CT studies were reviewed in consensus by two reviewers. Morphologic changes including volume and mean parenchymal density of the thyroid glands were evaluated. Maximum standardized uptake value (SUVmax) and total lesion glycolysis (TLG) were determined to evaluate metabolic changes. These parameters were compared between patients with chronic thyroiditis who received thyroid hormone replacement therapy and those who did not.


RESULTS
Of the 146 patients, 29 (20%) showed bilaterally diffuse uptake in the thyroid glands on the baseline PET-CT scan. The SUVmax showed a linear relationship with volume (r = 0.428, p = 0.021) and the mean parenchymal density (r = -0.385, p = 0.039) of the thyroid glands. In 21 of the 29 patients (72%) with hypothyroidism who received thyroid hormone replacement therapy, the volume, mean parenchymal density, SUVmax, and TLG of the thyroid glands showed no significant changes. In contrast, 8 of the 29 patients (28%) who did not receive thyroid hormone replacement therapy showed marked decreases in SUVmax and TLG.


CONCLUSIONS
Diffuse thyroid uptake on PET-CT represents active inflammation caused by chronic thyroiditis in patients with advanced breast carcinoma. Diffuse thyroid uptake may also address the concern about subclinical hypothyroidism which develops into overt disease during follow-up.
Tateishi
Ukihide
U
Department of Nuclear Medicine, University of Texas, MD Anderson Cancer Center, Houston, TX, USA. utateish@yokohama-cu.ac.jp
Gamez
Cristina
C
Dawood
Shaheenah
S
Yeung
Henry W D
HW
Cristofanilli
Massimo
M
Inoue
Tomio
T
Macapinlac
Homer A
HA
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000150:complications* / Q000473:pathology*; D002908:Chronic Disease; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism; D006801:Humans; D008875:Middle Aged; D049268:Positron-Emission Tomography; D012189:Retrospective Studies; D013961:Thyroid Gland / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology; D013966:Thyroiditis / Q000150:complications / Q000175:diagnosis / Q000378:metabolism* / Q000473:pathology*; D014057:Tomography, X-Ray Computed
D019788:Fluorodeoxyglucose F18