Delusory Radioiodine Uptake in Endometriotic Ovarian Cyst.

A 25-year-old woman with a known case of papillary thyroid carcinoma conventional type referred to our center for treatment with radioactive iodine after total thyroidectomy. She received 200 mCi of radioiodine, and in the whole-body scan 1 week after the radioiodine therapy, an area of increased absorption was seen on the right side of the pelvis, which was diagnosed as an endometriotic ovarian cyst in the follow-up examinations.

Aberrant Radioactive Iodine Uptake in Simple Ovarian Cyst: A Rare Finding.

I-131 whole body scan and therapy play an important role in the follow-up of differentiated thyroid carcinoma patients for the detection of residual thyroid tissue and metastatic disease. However, various false-positive findings have been reported in the literature which can appear as metastases. Here, we present one such case, in which an I-131 posttherapy scan revealed false-positive radioactive iodine uptake which localized to a simple ovarian cyst.

Value of the Postablative Thyroglobulin Measurements for Assessment of Disease-Free Status in Patients with Differentiated Thyroid Cancer.

AIM: The aim of the study is to evaluate the value of thyroid-stimulating hormone (TSH)-stimulated thyroglobulin (sTg) measurements by the end of the 1st-year postablation in differentiated thyroid cancer (DTC) patients with biochemical non complete response (indeterminate and incomplete response). PATIENTS AND METHODS: One hundred patients with DTC underwent near-total thyroidectomy and radioactive remnant ablation by iodine-131 (I131) with regular follow-up every 6 months during the first 2 years and at 6-12-month intervals thereafter by I131 whole-body scan (WBS), neck ultrasound, and sTg measurement in the hypothyroid state (TSH >30 mU/L). Patients were divided according to the imaging findings and sTg level into three groups: excellent response (ER) - no evidence of disease by imaging and sTg <1 ng/mL, indeterminate or acceptable response (AR) - nonspecific findings on imaging studies and sTg < 10 ng/mL, and incomplete response (IR) - patients with incomplete structural and/or incomplete biochemical response (sTg > 10 ng/mL). RESULTS: The follow-up at 6-month postablation showed ER in 3 (3%) patients, AR in 29 (29%) patients, and IR in 68 (68%) patients. The second follow-up at 9-12-month postablation showed dramatic biochemical response with ER, indeterminate, and IR in 50 (50%), 34 (34%), and 16 (16%) patients, respectively, and 14 (14%) patient had structural recurrence. This change is highly statistically significant (P = 0.00). In the last follow-up (ranges from 3 to 10 years), 53 (55.8%) patients achieved ER, 42 (44.2%) AR and no patient with non complete response. The change in patients with IR between the second and the last follow-up is also statistically significant (P = 0.001). CONCLUSION: sTg measurement by the end of the 1st year is more reliable in the follow-up of patients with DTC and biochemical non complete response and considered significant predictor of disease-free status. Patients with biochemical IR still have the chance to achieve ER or AR by the passage of time without additional therapies.

Bilateral Renal Metastasis of Hürthle Cell Thyroid Cancer with Discordant Uptake Between I-131 Sodium Iodide and F-18 FDG.

Renal metastasis of thyroid cancer is extremely rare. We report the case of a 62-year-old woman with Hürthle cell thyroid cancer (HCTC) with lungs, bones, and bilateral kidneys metastases. The renal metastatic lesions were clearly demonstrated by 131I whole body scan (WBS) with SPECT/CT. However, they exhibited false-negative results in 18F-FDG PET/CT, kidney ultrasonography, and contrast-enhanced CT scan. The findings imply that tumors have low glucose metabolism and are able to accumulate radioiodine, which is not commonly found in the relatively aggressive nature of HCTC. The patient received two sessions of 200 mCi 131I therapy within 6 months duration. There was complete treatment response as evaluated by the second post-therapeutic 131I SPECT/CT and serum thyroglobulin. To our knowledge, renal metastasis from HCTC with positive 131I but negative 18F-FDG uptake has not been reported in the literature. This case suggests that 131I SPECT/CT is useful for lesion localization and prediction of 131I therapy response.

The false-positive radioiodine I-131 uptake in the foreign body granuloma located in gluteal adipose tissue.

BACKGROUND: The purpose of using a whole-body scanning after the radioactive I-131 treatment is to screen functional residual or metastatic thyroid tissues. In whole-body scanning of some patients, false positive radioiodine I-131 uptakes may be seen in physiological uptake regions or atypical localizations. CASE REPORT: A 54 year-old woman underwent total thyroidectomy for papillary thyroid carcinoma. A positive appearance seen in the upper postero-lateral part of the right gluteal region was determined by a post-therapy I-131 whole body scan. The colour Doppler ultrasonography, magnetic resonance imaging features and histopathological characteristics of the excised lesion were presented. The lesion was demonstrated to be a foreign body granuloma. CONCLUSIONS: Unexpected positive findings in the post-therapy I-131 whole body scan should be confirmed with other imaging modalities in order to avoid unnecessary treatments. In uncertain situations, the diagnosis should be established histopathologically.

Bilateral Renal Metastasis of Hürthle Cell Thyroid Cancer with Discordant Uptake Between I-131 Sodium Iodide and F-18 FDG / 대한핵의학회잡지

Renal metastasis of thyroid cancer is extremely rare. We report the case of a 62-year-old woman with Hürthle cell thyroid cancer (HCTC) with lungs, bones, and bilateral kidneys metastases. The renal metastatic lesions were clearly demonstrated by ¹³¹I whole body scan (WBS) with SPECT/CT. However, they exhibited false-negative results in ¹⁸F-FDG PET/CT, kidney ultrasonography, and contrast-enhanced CT scan. The findings imply that tumors have low glucose metabolism and are able to accumulate radioiodine, which is not commonly found in the relatively aggressive nature of HCTC. The patient received two sessions of 200 mCi ¹³¹I therapy within 6 months duration. There was complete treatment response as evaluated by the second post-therapeutic ¹³¹I SPECT/CT and serum thyroglobulin. To our knowledge, renal metastasis from HCTC with positive ¹³¹I but negative ¹⁸F-FDGuptake has not been reported in the literature. This case suggests that ¹³¹I SPECT/CTis useful for lesion localization and prediction of ¹³¹I therapy response.

Renal Metastasis from Follicular Thyroid Carcinoma Diagnosed by I-131 Whole-body Scan Mimicking Renal Cell Carcinoma on Contrast-Enhanced Computed Tomography.

Clinically detectable well-differentiated metastatic thyroid carcinoma to the kidney is rare and should be differentiated from primary renal malignancy. We report a case of renal metastases from follicular thyroid carcinoma (FTC) diagnosed by I-131 whole body scan. Additional features of this case different from previous case reports are solitary renal metastasis on I-131 whole body scan and mimicry of renal cell carcinoma on contrast-enhanced computed tomography.

The Value of FDG-PET in Reoperation of the Recurrent Papillary Thyroid Carcinoma with Elevated Thyroglobulin Levels and Negative I131 WBS

PURPOSE: We evaluated the diagnostic accuracy and useful ness of FDG-PET to determine the proper extent of surgery in recurrent papillary thyroid cancer patients with elevated thyroglobulin levels and negative I131 WBS. METHODS: FDG-PET was performed in 16 recurrent papillary thyroid cancer patients with elevated thyroglobulin levels and negative I131 WBS. In 9 patients, FDG-PET was performed to localize the recurrent lesions. In 7 patients, the recurrent lesions were initially diagnosed by physical examination or other image studies and the FDG-PET was subsequently performed to detect additional recurrent lesions. All suspected lesions detected by FDG-PET and other studies were explored. RESULTS: Among the 9 patients in whom FDG-PET was performed to localize the recurrent lesions, the recurrent lesions were detected only by FDG-PET in 4 patients. Among the 7 patients in whom FDG-PET was performed additionally to detect additional recurrent lesions, another recurrent cervical regions were detected by FDG-PET in 2 patients. However, the same lesions were able to be identified by ultrasonography. A total of 26 cervical regions were explored in 16 patients. There were 4 FDG-PET false positive regions and 2 FDG-PET false negative regions. Unnecessary surgery was performed in 4 cervical regions in 4 patients. CONCLUSION: FDG-PET was very useful in detecting small early recurrent lesions but was unable to contribute to the detection of additional recurrent cervical regions in the pa-tients in which the recurrent lesion had already been by physical examination or other studies. Other image studies are necessary to supplement the FDG-PET in false positive or false negative cases.