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. 2016 Feb 25;4(1):2324709616633715.
doi: 10.1177/2324709616633715. eCollection 2016 Jan-Mar.

In Thyroidectomized Thyroid Cancer Patients, False-Positive I-131 Whole Body Scans Are Often Caused by Inflammation Rather Than Thyroid Cancer

Yana Basis Garger  1 , Mathew Winfeld  1 , Kent Friedman  1 , Manfred Blum  1
Affiliations

In Thyroidectomized Thyroid Cancer Patients, False-Positive I-131 Whole Body Scans Are Often Caused by Inflammation Rather Than Thyroid Cancer

Yana Basis Garger et al. J Investig Med High Impact Case Rep. .

Abstract

Objective. To show that I-131 false-positive results on whole-body scans (WBSs) after thyroidectomy for thyroid cancer may be a result of inflammation unassociated with the cancer. Methods. We performed a retrospective image analysis of our database of thyroid cancer patients who underwent WBS from January 2008 to January 2012 to identify and stratify false positives. Results. A total of 564 patients underwent WBS during the study period; 96 patients were referred for 99 I-131 single-photon emission computed tomography (SPECT/CT) scans to better interpret cryptic findings. Among them, 73 scans were shown to be falsely positive; 40/73 or 54.7% of false-positive findings were a result of inflammation. Of the findings, 17 were in the head, 1 in the neck, 4 in the chest, 3 in the abdomen, and 14 in the pelvis; 1 had a knee abscess. Conclusions. In our series, inflammation caused the majority of false-positive WBSs. I-131 SPECT/CT is powerful in the differentiation of inflammation from thyroid cancer. By excluding metastatic disease, one can properly prognosticate outcome and avoid unnecessary, potentially harmful treatment of patients with thyroid cancer.

Keywords: 131-iodine; PTC; WBS; false positive; inflammation; papillary thyroid cancer; thyroid cancer; whole body scan.

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Conflict of interest statement

Declaration of Conflicting Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Figures

Figure 1.
Figure 1.
Schematic of patients who underwent WBSs and SPECT/CTs and the findings of those studies. Abbreviations: WBS, whole body scan; SPECT/CT, single-photon emission computed tomography; IUD, intrauterine device.
Figure 2.
Figure 2.
Asymmetrical left knee uptake on an 8-day posttherapy WBS: a 53-year-old woman with a history of papillary thyroid carcinoma (PTC) was treated with surgery and 100 mCi of I-131. WBS at 6 and 8 days posttherapy demonstrated persistent asymmetric uptake at the left knee. The patient had a clinical history of a knee abrasion several days previously. Physical exam demonstrated a small abscess at the site of the abrasion, which corresponded anatomically to the area of increased uptake on WBS. Abbreviations: WBS, whole body scan.
Figure 3.
Figure 3.
Parotid duct stone resulting in obstruction and inflammation as seen on WBS and SPECT/CT. A 50-year-old woman with a history of PTC was treated with surgery and 100 mCi of I-131. Posttherapy WBS (3A) demonstrates left-neck activity that on SPECT/CT (3B) corresponded to a stone impacted in the submandibular salivary gland duct. Abbreviations: WBS, whole body scan; SPECT/CT, single-photon emission computed tomography.
Figure 4.
Figure 4.
Cryptic uptake in the chest, corresponding to bronchiectasis on SPECT/CT. A 56-year-old woman with a history of PTC treated with surgery and then 100 mCi of I-131. Posttherapy WBS (4A) demonstrates focal activity in the lungs. On SPECT/CT (4B), this area was diagnosed as bronchiectasis. Abbreviations: WBS, whole body scan; SPECT/CT, single-photon emission computed tomography.
Figure 5.
Figure 5.
Inflammation around an intrauterine device and at a menstruating uterus/cervix as seen on WBS and SPECT/CT. A 41-year-old woman with a history of PTC was treated with surgery and then 150 mCi of I-131. Posttherapy WBS (5A) demonstrates 2 foci in the pelvis that on SPECT/CT (5B) were confirmed to represent accumulation of I-131 in the uterine cavity associated with an intrauterine device and at the cervix. Abbreviations: WBS, whole body scan; SPECT/CT, single-photon emission computed tomography.
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References

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