Feasibility of Extraoral 3D Ultrasound for Detection of MRI-Occult Oral Squamous Cell Carcinoma
Abstract
Purpose
To demonstrate feasibility of three-dimensional ultrasound (3DUS) for the detection of oral squamous cell carcinoma (OSCC) and to evaluate its potential as a pre-clinical screening tool.
Methods
An initial study was conducted in healthy volunteers to compare a custom handheld motorized 3D scanning device against a commercial 3DUS system (Philips Healthcare). Upon establishing the commercial system as the optimal approach, a second ethics approved study was performed at a tertiary care centre on patients within a week of OSCC tumor resection. Patients were scanned using both 3DUS and a 3.0 T MRI (GE Healthcare). In cases where the tumor was visible on both modalities, a radiologist and trained observed segmented tumor boundaries. Geometric agreement between modalities was quantified using the 95 percent Hausdorff distance and Dice-Sorensen similarity coefficient (DSC).
Results
Among ten participants, tumor visibility was assessed across two phases. During the protocol optimization phase, two patients presented tumors visible on both 3DUS and MRI, confirming the feasibility of multi-modal geometric comparison. Subsequently, in a patient imaged using the fully optimized protocol, a 2.5 cm OSCC tumor (confirmed by contrast enhanced CT) was successfully identified in the 3DUS volume. Notably, this mass was not visible on MRI. The 3DUS measurement of 2.9 cm approximated the final excised tumor size of 2.2 cm, successfully identifying pathology that was undetected on MRI.
Conclusion
This work validates the use of extraoral and submental 3DUS to detect and measure OSCC tumors, advancing beyond previous proof-of-concept studies. The research successfully optimized a combined MRI and 3DUS imaging protocol, demonstrating that 3DUS can provide critical volumetric data even when tumors are indistinguishable on MRI. Consequently, this establishes 3DUS as a viable, cost-effective tool for pre-surgical tumor quantification.