ENDOCRINE TUMOURS: Imaging in the follow-up of differentiated thyroid cancer: current evidence and future perspectives for a risk-adapted approach

Abstract

The clinical and epidemiological profiles of differentiated thyroid cancers (DTCs) have changed in the last three decades. Today's DTCs are more likely to be small, localized, asymptomatic papillary forms. Current practice is, though, moving toward more conservative approaches (e.g. lobectomy instead of total thyroidectomy, selective use of radioiodine). This evolution has been paralleled and partly driven by rapid technological advances in the field of diagnostic imaging. The challenge of contemporary DTCs follow-up is to tailor a risk-of-recurrence-based management, taking into account the dynamic nature of these risks, which evolve over time, spontaneously and in response to treatments. This review provides a closer look at the evolving evidence-based views on the use and utility of imaging technology in the post-treatment staging and the short-and long-term surveillance of patients with DTCs. The studies considered range from cervical US with Doppler flow analysis to an expanding palette of increasingly sophisticated second-line studies (cross-sectional, functional, combined-modality approaches), which can be used to detect disease that has spread beyond the neck and, in some cases, shed light on its probable outcome.

Thyroid cancer: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up

“…A WBS can be carried out after the administration of diagnostic or therapeutic doses of RAI. Because its sensitivity is low (27%-55%), diagnostic WBS is not indicated during follow-up [IV, A] [64]. Uptake is highly specific (91%-100%) for the presence of thyroid tissue, but false-positive results are possible.…”

“…Uptake is highly specific (91%-100%) for the presence of thyroid tissue, but false-positive results are possible. In these cases, single-photon emission computed tomography or computed tomography (CT) offers better anatomic resolution [64].…”

“…All forms of RAI treatment should be deferred for at least 6 weeks after administration of any iodinated contrast medium. Contrast-enhanced magnetic resonance imaging (MRI) is appropriate for exploring the neck, liver, bones and brain [64]. MRI of the neck is subject to substantial image degradation due to respiratory motion, and a CT scan is often a better alternative.…”

An update on the management of low-risk differentiated thyroid cancer

“…Recurrences in the surgical bed usually appear hypoechoic with microcalcifications, cystic components, irregular margins, and increased vascularity, but falsepositive ultrasonographic findings are frequent (26-35%) in particular during the early follow-up period due to the presence of inflammation and scar tissue (Lamartina et al 2016a).…”

“…Given the rarity of distant metastases in patients with lowrisk DTC, cross-sectional imaging including computed tomography scan, MRI and 18 fluorodeoxyglucose positron emission tomography (18-FDG-PET) are not routinely used in these patients, but can provide valuable information in certain cases (Leboulleux et al 2007b, Lamartina et al 2016a).…”