99 Thyroid Cancer 2

CASE 99

Clinical Presentation

A 24-year-old woman presents with palpable right-sided neck nodes. A CT scan is requested for further assessment.

Fig. 99.1

Fig. 99.2 Initial whole body scan.

Fig. 99.3 Post-therapy scan.

Fig. 99.4 Three years later: whole body scan.

Technique

• ¹³¹I, 2 mCi (74 MBq) orally. Planar imaging with a high-energy collimator 2 days later (Figs. 99.2 and 99.4).

• ¹³¹I, 150 mCi (5550 MBq) orally (therapy dose). Planar imaging with a high-energy collimator 7 days later (Fig. 99.3).

Image Interpretation

CT images at two levels through the neck (Fig. 99.1) demonstrate multiple rim-enhancing enlarged lymph nodes (arrowheads), many with cystic centers. A low-density lesion is also seen in the right lobe of the thyroid (arrow). This is biopsied and shown to be papillary thyroid cancer. Following thyroidectomy, a ¹³¹I scan is performed (Fig. 99.2) in preparation for radioiodine therapy. This demonstrates uptake in the thyroid remnants, with no metastases identified. A rectangular area of activity to the right of the head (Figs. 99.2 and 99.4) is within a standard of known activity placed next to the patient for uptake calcification purposes.

Therapy

The patient was administered an oral dose of 150 mCi of ¹³¹I for thyroid ablation and adjuvant therapy. A post-therapy scan 1 week later (Fig. 99.3

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