Multimodal Ultrasound in Evaluating Radiotherapy Efficacy for Vaginal Squamous Cell Carcinoma: A Case Report

Vaginal malignancy is rare and carries a poor prognosis. MRI is the reference standard for staging and follow-up, but cost and availability are limiting. We describe the use of high-frequency transrectal ultrasound (HF-TRUS) for pre-treatment mapping and early response assessment of primary vaginal cancer.

A 65-year-old woman presented with post-menopausal bleeding for 20 days. Histology of the right vaginal fornix revealed high-grade squamous intraepithelial lesion. Clinical stage cT1N0M0 poorly differentiated carcinoma was confirmed, and curative radiotherapy was planned. HF-TRUS (12 MHz linear array, sagittal and axial planes) showed two heterogeneous hypoechoic nodules on the anterior vaginal wall. Gel filling in the vaginal canal created an effective acoustic window, which significantly improved the delineation of the vaginal wall layers and the lesion boundaries. After 45 Gy external-beam radiotherapy, the nodules decreased by 15.2% and 18.2%, respectively; at 6 months post-completion of brachytherapy, one nodule had virtually disappeared. Doppler signal decreased concurrently. MRI at the same time-points provided identical size regression data.

This case validates HF-TRUS with contrast enhancement as a reliable MRI alternative for monitoring radiotherapy in vaginal cancer. The ultrasound accurately tracked tumor size and blood flow changes, with results matching MRI. This quick, clinic-based technique fills a critical gap when MRI is not available or contraindicated.