High-Frequency Intraoral Ultrasound for Preoperative Assessment of Depth of Invasion for Early Tongue Squamous Cell Carcinoma: Radiological–Pathological Correlations

Abstract

The eighth edition of the TNM classification officially introduced “depth of invasion” (DOI) as a criterion for determining the T stage in tongue squamous cell carcinoma. The DOI is a well-known independent risk factor for nodal metastases. In fact, several experts strongly suggest elective neck dissection for tongue cancer with a DOI > 4 mm due to the high risk of early and occult nodal metastases. Imaging plays a pivotal role in preoperative assessments of the DOI and, hence, in planning the surgical approach. Intraoral ultrasound (IOUS) has been proposed for early-stage SCC of the oral tongue as an alternative to magnetic resonance imaging (MRI) for local staging. The aim of this work is to investigate the accuracy of IOUS in the assessment of the DOI in early oral SCC (CIS, pT1, and pT2). A total of 41 patients with tongue SCCs (CIS-T2) underwent a preoperative high-frequency IOUS. An IOUS was performed using a small-size, high-frequency hockey-stick linear probe. The ultrasonographic DOI (usDOI) was retrospectively compared to the pathological DOI (pDOI) as the standard reference. In patients who underwent a preoperative MRI, their usDOI, magnetic resonance DOI (mriDOI), and pDOI were compared. Specificity and sensitivity for the IOUS to predict a pDOI > 4 mm and to differentiate invasive and noninvasive tumors were also evaluated. A high correlation was found between the pDOI and usDOI, pDOI and mriDOI, and usDOI and mriDOI (Spearman’s ρ = 0.84, p < 0.0001, Spearman’s ρ = 0.79, p < 0.0001, and Spearman’s ρ = 0.91, p < 0.0001, respectively). A Bland–Altman plot showed a high agreement between the usDOI and pDOI, even though a mean systematic error was found between the usDOI and pDOI (0.7 mm), mriDOI and pDOI (1.6 mm), and usDOI and mriDOI (−0.7 mm). The IOUS was accurate at determining the T stage (p < 0.0001). The sensitivity and specificity for the IOUS to predict a pDOI ≥4 mm were 92.31% and 82.14%, respectively, with an AUC of 0.87 (p < 0.0001). The specificity, sensitivity, negative predictive value (NPV), and positive predictive value (PPV) for the IOUS to predict an invasive cancer were 100%, 94.7%, 60%, and 100%, respectively. The AUC was 0.8 (95% CI 0.646–0.908, p < 0.0001). The IOUS was accurate in a preoperative assessment of a pDOI and T stage, and can be proposed as an alternative to MRI in the preoperative staging of tongue SCC.

Ultrasonography use for tongue cancer management: A scoping review

“…The majority of the studies included in the current scoping review demonstrated a reliable potential of intraoral ultrasound to more efficiently estimate depth of invasion and tumor thickness pre-operatively, demonstrating lower overestimations than CT and MRI, which are more strongly affected by peritumoral edema and reactive inflammation. 11,13,[16][17][18][19] Moreover, the occurrence of metal artifacts is frequently reported as an important limitation of CT, which precludes detailed tongue cancer analyses in a large number of patients that often carry amalgam dental restorations. 6,13 It is known that the higher the depth of invasion of tongue cancer, the higher the frequency of metastases to the cervical lymph nodes.…”

Radiomics analysis of intraoral ultrasound images for prediction of late cervical lymph node metastasis in patients with tongue cancer

“…Previous studies have reported the usefulness of intraoral ultrasonography in the evaluation of tongue cancer 5–11 . Lesion length, thickness, depth of invasion, and margins are reported factors associated with late cervical lymph node metastasis, and intraoral ultrasonographic images may contain features related to tongue cancer prognosis 5,7,11 .…”

“…Previous studies have reported the usefulness of intraoral ultrasonography in the evaluation of tongue cancer. [5][6][7][8][9][10][11] Lesion length, thickness, depth of invasion, and margins are reported factors associated with late cervical lymph node metastasis, and intraoral ultrasonographic images may contain features related to tongue cancer prognosis. 5,7,11 Although various studies have reported cervical lymph node metastasis in patients with tongue cancer, insufficient evidence is available to determine whether prophylactic dissection should be performed.…”

Ultrasonographic features of mass lesions in the oral submucosal epithelium using intraoral ultrasonography

“…Furthermore, the relationship between intraoral ultrasonographic images and late cervical lymph node metastasis has been shown 7–10 . This technique has also been used in measuring the depth of tongue cancer 11–13 . However, few studies have reported on the examination of common submucosal intraoral benign lesions, such as hemangiomas, irritation fibromas, mucous cysts, lipomas, and pleomorphic adenomas, using ultrasonography.…”

“…[7][8][9][10] This technique has also been used in measuring the depth of tongue cancer. [11][12][13] However, few studies have reported on the examination of common submucosal intraoral benign lesions, such as hemangiomas, irritation fibromas, mucous cysts, lipomas, and pleomorphic adenomas, using ultrasonography. We aimed to investigate the features of benign mass lesions in the submucosal epithelium of the oral cavity and to propose a differential diagnosis for each lesion.…”