Utility of quantitative contrast-enhanced ultrasound: a valuable prediction for capsule invasion assessment in...

Papillary thyroid cancer (PTC) patients with capsule invasion have a risk of poor clinical outcomes. The aim of this study was to assess the diagnostic accuracy of quantitative contrast-enhanced ultrasound (CEUS) for detecting capsule invasion and identifying the relationship between capsule invasion and sonographic features of PTC.

Patients confirmed as having PTC underwent conventional ultrasound (US) and CEUS examinations. The conventional US and qualitative CEUS features of the PTC nodules and capsule invasion were evaluated and classified separately. The accuracy of conventional US and qualitative CEUS in predicting capsule invasion was compared separately. Moreover, quantitative parameters were analyzed in different groups. The presence or absence of capsule invasion and cervical lymph node metastasis (LNM) was confirmed by the pathological results.

The study finally included 107 patients with 109 PTC nodules. A total of 58 (53.2%) of PTC nodules had no capsule invasion, whereas the remaining 51 had capsule invasion [including 19 patients with extracapsular extension (ECE)]. A significant difference was found in nodules with non-capsule invasion, single capsule invasion, and ECE between the LNM and non-LNM groups (χ²=11.34, P<0.01). Single capsule invasion and ECE demonstrated a significant linear trend with cervical LNM (r=0.309, P=0.001). Independent predictive conventional US and qualitative CEUS features included nodule size, contour bulging, and capsular abutment on CEUS and discontinuous capsular enhancement on CEUS. In quantitative CEUS parameters, peak intensity (PI) was most valuable for predicting capsule invasion, and significant differences were found between the non-capsule invasion group (12.7±1.2) and the single capsule invasion group (29.2±5.2), and the non-capsule invasion group (12.7±1.2) and the ECE group (35.5±6.4). Moreover, the quantitative CEUS-assisted US equation demonstrated the best diagnostic performance compared with the conventional US and qualitative CEUS approach.

Compared with conventional US and qualitative CEUS, quantitative CEUS is a more reliable and objective imaging method to predict capsule invasion of PTC.