Extremity Radioactive Iodine Uptake on Post-therapeutic Whole Body Scan in Patients with Differentiated Thyroid Cancer

Document Type : Original Article


Department of Nuclear Medicine, Kanazawa University, Kanazawa, Ishikawa, Japan


Objective(s): We investigated a frequency of lower extremity uptake on the radioactive iodine (RAI) whole body scan (WBS) after RAI treatment in patients with differentiated thyroid cancer, in order to retrospectively examine whether or not the frequency was pathological.
Methods: This retrospective study included 170 patients with thyroid cancer, undergoing RAI treatment. Overall, 99r (58%) and 71 (42%)patients received single and multiple RAI treatments, respectively. Post-therapeutic WBS was acquired after 3 days of RAI administration. For patients with multiple RAI treatments, the WBS of their last RAI treatment was evaluated. Lower extremity uptake on post-therapeutic WBS was classified into 3 categories: bilateral femoral uptake (type A), bilateral femoral and tibia uptake (type
B), and uptake in bilateral upper and lower extremities (type C). Then, the patients with RAI uptake in the lower extremities on WBS were analyzed with clinical parameters.
Results: Overall, 99 patients (58%) had the extremity uptake on their posttherapeutic RAI WBS. As the results indicated, 42 ,53, and 4 patients had type A, type B, and type C uptakes, respectively. Lower extremity uptake was significantly associated with younger age, not only in subjects with multiple RAI treatments but also in all the patients (P<0.05). Accumulation in patients with multiple RAI treatments was more frequent than patients with single RAI treatment (P<0.05). Lower extremity uptake was not associated with counts of the white blood cell count, hemoglobin level, platelet count, estimated glomerular filtration rate, effective half-time of RAI, serum TSH level, and anti-Tg concentration.
Conclusion: About half of the patients had lower extremity uptake on the posttherapeutic RAI WBS, especially younger patients and those with multiple courses of RAI treatment. Bilateral lower extremity’s RAI uptake on the posttherapeutic WBS should be considered as physiological RAI distribution in bone marrow.


Main Subjects

1. Cooper DS, Doherty GM, Haugen BR, Kloos RT, Lee SL, Mandel SJ, et al. Revised American Thyroid Association management guidelines for patients with thyroid nodules and differentiated thyroid cancer. Thyroid. 2009; 19(11):1167 214.
2. Kao PF, Chang HY, Tsai MF, Lin KJ, Tzen KY, Chang CN. Breast uptake of iodine-131 mimicking lung metastases in a thyroid cancer patient with a pituitary tumour. Br J Radiol. 2001;74(880):378-81.
3. Hsiao E, Huynh T, Mansberg R, Bautovich G, Roach P. Diagnostic I-123 scintigraphy to assess potential breast uptake of I-131 before radioiodine therapy in a postpartum woman with thyroid cancer. Clin Nucl Med. 2004; 29(28):498-501.
4. Basu S, Moghe SH. Unusual unilateral breast 131I uptake related to breastfeeding practice. Clin Radiol. 2009;64(7):743-4.
5. Brucker-Davis F, Reynolds JC, Skarulis MC, Fraker DL, Alexander HR, Weintraub BD, et al. False-positive iodine-131 whole-body scans due to cholecystitis and sebaceous cyst. J Nucl Med. 1996;37(10):1690-3.
6. Bohnen NI, Charron M. Isolated lower extremity I-131 bone marrow uptake in a runner. Clin Nucl Med. 2001;26(2):163-4.
7. Matsuo S, Imai E, Horio M, Yasuda Y, Tomita K, Nitta K, et al. Revised equations for estimated GFR from serum creatinine in Japan. Am J Kidney Dis. 2009;53(6):982-92.
8. Anner RM, Drewinko B. Frequency and significance of bone marrow involvement by metastatic solid tumors. Cancer. 1977; 39(3):1337-44.
9. Rufini V, Salvatori M, Saletnich I, Luzi S, Fadda G, Shapiro B, et al. Disseminated bone marrow metastases of insular thyroid carcinoma detected by radioiodine whole-body scintigraphy. J Nucl Med. 1996;37(4):633-6.
10. Moore SG, Dawson KL. Red and yellow marrow in the femur: age-related changes in appearance at MR imaging. Radiology. 1990;175(1):219-23.
11. Vande Berg BC, Lecouvet FE, Moysan P, Maldague B, Jamart J, Malghem J. MR assessment of red marrow distribution and composition in the proximal femur: correlation with clinical and laboratory parameters. Skeletal Radiol. 1997;26(10):589-96.
12. Ricci C, Cova M, Kang YS, Yang A, Rahmouni A, Scott WW Jr, et al. Normal age-related patterns of cellular and fatty bone marrow distribution in the axial skeleton: MR imaging study. Radiology. 1990;177(1):83-8.
13. Kim SC, Krynyckyl BR, Machac J, Kim CK. Patterns of red marrow in the adult femur. Clin Nucl Med. 2006;31(12):739-41.
14. Hung BT, Huang SH, Huang YE, Wang PW. Appropriate time for post-therapeutic I-131 whole body scan. Clin Nucl Med. 2009;34(6):339-42.