Ultrasound, CT Similarly Effective for Thyroid Cancer Metastases

NEW YORK (Reuters Health) – Ultrasonography and computed tomography (CT) appear to be equally good at detecting papillary thyroid cancer within the lateral compartment, with CT more sensitive and ultrasound more specific for central-compartment cervical lymph node metastasis, researchers in Canada report.

“Current practice guidelines recommend ultrasonography for preoperative assessment of papillary thyroid cancer, particularly to look for lateral cervical compartment lymph node metastasis. However, we found that CT had similar accuracy to ultrasonography for this purpose,” Dr. Mostafa Alabousi of McMaster University, in Hamilton, told Reuters Health by email.

“The results of our study suggest there may be a role for CT in the preoperative staging of papillary thyroid cancer patients, potentially even as an adjunct to ultrasonography,” study co-author Dr. Abdullah Alabousi, also of McMaster, added by email.

In a systematic review of the literature, the two researchers and their colleagues identified 47 studies reporting on the diagnostic accuracy of ultrasound, CT, or both in nearly 32,000 individuals with treatment-naive papillary thyroid cancer, including 12,771 with cervical lymph node metastasis and 1,747 with extrathyroidal thyroid extension.

Using bivariate random-effects model meta-analysis and multivariable meta-regression modeling, they found that, for lateral compartment cervical lymph node metastasis, ultrasonography and CT showed similar sensitivity (73% and 77%, respectively; P=0.11) and specificity (89% and 88%, respectively; P=0.79).

For central compartment metastasis, ultrasonography sensitivity was 28% vs. 39% with CT (P=0.004), while ultrasonography specificity was 95% vs. 87% in CT (P<0.001), the team reports in JAMA Otolaryngology-Head & Neck Surgery. Ultrasonography showed 91% sensitivity and 47% specificity for extrathyroidal extension.

“A main strength of our study is the number of studies and patient observations we have included in our analysis and synthesis of results,” Dr. Mostafa Alabousi said. “A main weakness is that, although we compare the diagnostic accuracy of these imaging modalities, these findings do not necessarily reflect changes in management.”

“The study is important because thyroid nodules are most often incidentally identified on CT, and there are questions in clinical practice about how to best manage them,” Dr. Ammar Chaudhry, an assistant clinical professor of diagnostic radiology at City of Hope Comprehensive Cancer Center in Duarte, California, told Reuters Health by email. “For example, if a thyroid lesion is identified on CT, should it always be followed with an ultrasound or is CT-based assessment sufficient?”

“These findings reassure clinicians that not all lesions identified on CT need to be followed up with ultrasound,” added Dr. Chaudhry, who was not involved in the study.

“The study focuses on papillary thyroid cancer, which is by far the most common in histology,” Dr. Chaudhry noted. “However, a key limitation of the study is that in real-life scenarios, the histology of newly identified thyroid nodules is unknown. These results do not help answer questions related to the evaluation of newly diagnosed thyroid lesions in which the histology is unknown.”

“In newly identified thyroid lesions, the Thyroid Imaging Reporting and Data System (TI-RADS) would help clinicians properly work up thyroid nodules,” he said.

The authors recommend further research of the role of CT for papillary thyroid cancer staging, possibly as an adjunct to ultrasonography.

SOURCE: https://bit.ly/3INlavX JAMA Otolaryngology-Head & Neck Surgery, online November 24, 2021.

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