Is follow-up ultrasound effective for tracking the recurrence of papillary thyroid cancer -- especially in patients with undetectable serum thyroglobulin (Tg) levels? Not necessarily, according to a study published in the October issue of the Journal of Ultrasound in Medicine.
The findings indicate that eliminating follow-up ultrasound could serve patients in the long run by relieving anxiety prompted by false positives, wrote a team led by Samantha Epstein from the University of Virginia. Previous research has shown that using follow-up ultrasound exams to monitor thyroid cancer recurrence can lead to false-positive results in up to 67% of patients.
"[An] important aspect of patient care to consider is anxiety related to false-positive results from neck ultrasound examinations performed when the serum Tg is undetectable," Epstein and colleagues noted.
Papillary thyroid cancer is the most common cancer of the thyroid gland. The standard of care for patients with lesions larger than 4 cm or metastatic disease is surgical removal, the group wrote.
After surgery, patients often undergo radioactive iodine-131 (RAI) ablation therapy, which destroys any residual thyroid tissue; they then have repeat neck ultrasound exams and Tg blood tests to monitor for cancer recurrence, usually six to 12 months after the ablation therapy and thereafter at six- to 12-month intervals. Up to 20% of patients with thyroid cancer have recurrences (J Ultrasound Med, October 2018, Vol. 37:10, pp. 2325-2331).
Epstein and colleagues sought to assess whether neck ultrasound identified recurrent disease in 76 patients with undetectable serum Tg levels after total thyroidectomy and RAI ablation for thyroid cancer. They used pathologic results from ultrasound-guided fine-needle aspiration or follow-up for at least a year as the reference standard for recurrence.
The patients collectively had a total of 257 neck ultrasound exams between April 2010 and April 2017. This included 19 exams in 18 patients in which ultrasound indicated the possibility of disease recurrence. However, none of these 18 patients actually had recurrent disease as measured by fine-needle aspiration or one-year follow-up.
The researchers also assessed 65 patients with elevated serum Tg levels, indicating the possibility of disease recurrence. They performed 24 ultrasound exams on 22 patients; 12 of these patients underwent fine-needle aspiration, and nine of them had results indicating cancer. Seven patients had follow-up ultrasound scans that did not change the initial findings, and three were lost to follow-up.
Because the diagnostic yield of neck ultrasound for thyroid cancer recurrence was significantly lower in patients with undetectable serum Tg levels than in those with elevated levels (p = 0.001), the researchers concluded that ultrasound isn't necessary.
"The results of this retrospective study support the elimination of neck ultrasound as part of routine surveillance of patients with [papillary thyroid cancer] and an undetectable serum Tg level. ... Nearly all (91.2%) neck ultrasound examinations in this subgroup yielded negative findings for abnormalities, and although 19 examinations raised the possibility of recurrence, no recurrences were identified by fine-needle aspiration or follow-up of at least one year," they wrote.
![Examples of ultrasound findings and techniques. (A) Images in a 39-year-old male patient with a mass in the left thigh. The mass is heterogeneous on the B-mode US image (compared with the patient in D) and showed increased microvascularity (superb microvascular imaging [SMI]) and shear-wave elastography (SWE) values. Undifferentiated pleomorphic sarcoma was diagnosed at biopsy (with pleomorphic rhabdomyosarcoma in surgical specimen). (B) Images in an 18-year-old male patient with a mass in the left leg. The mass is hypoechoic on the B-mode image, with no other findings suggestive of malignancy. The lesion is in contact with the cortex of the tibia, which is slightly irregular. CT revealed a doubtful anteromedial tibial erosion. The microvascular study demonstrated high vascularization, suggestive of malignancy. Periosteal Ewing sarcoma was diagnosed with both histologic and immunohistochemical confirmation. (C) Images in a 69-year-old female patient with a lump growing on the outside of the left leg. Multiple SWE examinations were performed (please note the high values obtained in the measurements, whereas the color map highlights the stiffness relative to adjacent tissues). SMI showed areas of increased vascularization to target for sampling. Undifferentiated spindle cell sarcoma was diagnosed at biopsy, with residual leiomyosarcoma in the surgical specimen after neoadjuvant therapy. (D) Images in a 56-year-old female patient with a mass in the right thigh. The mass is heterogeneous at both B-mode ultrasound (similar to patient A) and MRI (coronal T2-weighted spectral attenuated inversion recovery [SPAIR]; T1-weighted pre-contrast and postcontrast imaging), which even shows uptake after the administration of paramagnetic contrast material, which is traditionally suggestive of malignancy. Low values at SMI and elastography are suggestive of benignity. Spindle cell lipoma was diagnosed at biopsy, with atypical spindle cell lipomatous tumor in the surgical specimen.](https://img.auntminnie.com/mindful/smg/workspaces/default/uploads/2026/08/images-radiol250278fig2.APCFLSvX6p.jpg?auto=format%2Ccompress&fit=crop&h=100&q=70&w=100)
![Examples of ultrasound findings and techniques. (A) Images in a 39-year-old male patient with a mass in the left thigh. The mass is heterogeneous on the B-mode US image (compared with the patient in D) and showed increased microvascularity (superb microvascular imaging [SMI]) and shear-wave elastography (SWE) values. Undifferentiated pleomorphic sarcoma was diagnosed at biopsy (with pleomorphic rhabdomyosarcoma in surgical specimen). (B) Images in an 18-year-old male patient with a mass in the left leg. The mass is hypoechoic on the B-mode image, with no other findings suggestive of malignancy. The lesion is in contact with the cortex of the tibia, which is slightly irregular. CT revealed a doubtful anteromedial tibial erosion. The microvascular study demonstrated high vascularization, suggestive of malignancy. Periosteal Ewing sarcoma was diagnosed with both histologic and immunohistochemical confirmation. (C) Images in a 69-year-old female patient with a lump growing on the outside of the left leg. Multiple SWE examinations were performed (please note the high values obtained in the measurements, whereas the color map highlights the stiffness relative to adjacent tissues). SMI showed areas of increased vascularization to target for sampling. Undifferentiated spindle cell sarcoma was diagnosed at biopsy, with residual leiomyosarcoma in the surgical specimen after neoadjuvant therapy. (D) Images in a 56-year-old female patient with a mass in the right thigh. The mass is heterogeneous at both B-mode ultrasound (similar to patient A) and MRI (coronal T2-weighted spectral attenuated inversion recovery [SPAIR]; T1-weighted pre-contrast and postcontrast imaging), which even shows uptake after the administration of paramagnetic contrast material, which is traditionally suggestive of malignancy. Low values at SMI and elastography are suggestive of benignity. Spindle cell lipoma was diagnosed at biopsy, with atypical spindle cell lipomatous tumor in the surgical specimen.](https://img.auntminnie.com/mindful/smg/workspaces/default/uploads/2026/08/images-radiol250278fig2.APCFLSvX6p.jpg?auto=format%2Ccompress&dpr=2&fit=crop&h=167&q=70&w=250)
