Photoacoustic/Ultrasonic Dual-Modality Imaging in the Differential Diagnosis of Subungual Tumors

Subungual tumors present diagnostic challenges due to their concealed location and overlapping clinical features. Accurate non-invasive differentiation between benign and malignant lesions is crucial for treatment planning.

To evaluate the efficacy of photoacoustic/ultrasound (PA/US) dual-modality imaging in distinguishing benign from malignant subungual tumors.

A total of 29 patients with subungual lesions (22 benign, 7 malignant) were prospectively enrolled. All underwent PA/US imaging using the Resona Y·PanGu system. Parameters including oxygen saturation (SO₂), total hemoglobin, elasticity and vascularity were analyzed. Diagnostic performance was assessed using receiver operating characteristic analysis with histopathology as the gold standard.

PA/US imaging demonstrated high diagnostic efficacy. The SO₂ value in subungual malignant tumor (51.78% [95% confidence interval, 49.41%-53.47%]) was significantly lower than in benign tumors (79.50% [95% confidence interval, 72.55%-84.68%]). SO₂ achieved an AUC of 0.980 for differentiating subungual malignant tumors. At an optimal cut-off value of ≤67.07%, the internally validated sensitivity and specificity were 85.7% and 85.7%, respectively, robustly mitigating optimism bias.

PA/US dual‑modality imaging, particularly SO₂ measurement, may offer a useful non‑invasive tool for the differential diagnosis of subungual tumors.