Radioiodine SPET/CT guided needle aspiration as a useful technique for recurrence surveillance in a thyroidectomized differentiated thyroid cancer patient with negative US and serum Tg and positive Tg of the lymph node aspirate.

To the Editor: Although diagnostic radioiodine scintigraphy or single photon emission tomography/computed tomography (SPET/CT) have been widely used in the evaluation of recurrence in thyroidectomized differentiated thyroid cancer patients, these techniques have not been generally recommended for this purpose or for biopsy purposes, especially in low-risk patients [1-4]. In addition, normal radioiodine uptake in the remnant of the thyroidectomized thyroid tissue without previous iodine-131 (131I) ablation hampers the detection of loco regional metastases. Fusion imaging by SPET/CT can better localize and differentiate radioiodine uptake related to metastases from benign causes of uptake [5, 6]. The author experienced a thyroidectomized, but not 131I ablated, papillary thyroid cancer (PTC) patient in whom radioiodine SPET/CT scintigraphy (Discovery NM/CT 670, GE Healthcare, Waukesha, WI, USA) specified and localized a lymph node metastasis, while ultrasonography (US) (Antares Premium edition, Siemens Medical Solutions USA, Ultrasound Division, Issaquah, WA, USA) and thyroglobulin (Tg) after thyroid stimulating hormone (TSH) stimulation were negative (Fig. 1). The 131I ablation was not performed to the patient because the patient belonged to the low-risk group according to the 2009 ATA guidelines [1]. A 43 years old female PTC patient, stage I T1MxMx, nine months after total thyroidectomy, in which a 1.5cm sized intrathyroidal tumor, lymph nodes was not assessed, underwent cervical US and diagnostic123I SPET/CT scintigraphy (Fig. 1). Her Tg after TSH stimulation was 1.61ng/mL. Although the 123I scan revealed three foci of abnormal uptake at the anterior and lateral neck, US showed normal lymph nodes (normal sized, hypoechoic lymph nodes with preserved hilar shadow) on both sides of the neck (Fig. 1). Considering the US findings and the low TSH stimulated Tg, the patient did not undergo further studies of radioiodine uptake. Six months later, she underwent the same surveillance work up including SPET/CT imaging. Ultrasonography again showed normal lymph nodes on both sides of the neck and TSH stimulated Tg was low: 1.32ng/mL. Two foci of increased uptake at the midline of the neck seemed as thyroid remnant tissue uptake, because there was no Original Case-Correspondence