The Role of Multiparametric High-Frequency Ultrasound of Basal Cell Carcinoma in Photodynamic Therapy

Objective: To evaluate the potential of multiparametric high-frequency ultrasound (18–24 MHz) for monitoring early changes after photodynamic therapy (PDT) in patients with basal cell carcinoma (BCC).

Materials and Methods. The prospective, single-center study included 31 patients with 51 histologically confirmed basal cell carcinoma lesions. All patients underwent multiparametric ultrasound imaging using an Aplio i800 ultrasound scanner (Canon, Japan) with 18–24 MHz linear transducers before and 24 hours after the PDT session. The protocol included evaluation of the tumor using B-mode, Doppler, and power Doppler mapping, including microcirculation (ADF and SMI) assessment with VI calculation, strain elastography, and fluorescence spectrometry.

Results. Before treatment, all cutaneous lesions were presented as hypoechoic lesions with clear margins, an average thickness of 3.7 ± 1.2 mm, a heterogeneous solid structure, and hypervascularisation (VI 32.4 ± 4.1). 24-hours after PDT, a statistically significant decrease in VI to 4.2 ± 1.8 (p < 0.001) was observed. B-mode revealed an increase in tumor thickness to 4.4 ± 1.3 mm, decreased marginal clarity, and signs of perifocal edema. Fluorescence contrast decreased from 1:4 to 1:1. Elastography did not show significant changes in the early stages.

Conclusion. Multiparametric ultrasound with high-frequency transducers (18–24 MHz) is an informative, noninvasive method for early monitoring of PDT efficacy. The most significant ultrasound feature of treatment response is a significant reduction in intratumoral blood flow, quantified using micro-Doppler techniques. This is due to the primary mechanism of PDT action –photochemical damage to tumor microvasculature and the development of coagulative necrosis. 

1. Peris K., Fargnoli M.C., Garbe C. et al. Diagnosis and treatment of basal cell carcinoma: European consensus-based interdisciplinary guidelines. Eur. J. Cancer. 2019; 118: 10–34. https://doi.org/10.1016/j.ejca.2019.06.003

2. Morton C.A., Szeimies R.M., Basset-Seguin N. et al. European Dermatology Forum guidelines on topical photodynamic therapy 2019 Part 1: treatment delivery and established indications – actinic keratosis, Bowen's disease and basal cell carcinomas. J. Eur. Acad. Dermatol. Venereol. 2019; 33 (12): 2225–2238. https://doi.org/10.1111/jdv.16017

3. Agostinis P., Berg K., Cengel K.A. et al. Photodynamic therapy of cancer: an update. CA Cancer J. Clin. 2011; 61 (4): 250–281. https://doi.org/10.3322/caac.20114

4. Wortsman X. Ultrasound in Skin Cancer: Why, How, and When to Use It? Cancers. 2024; 16 (19): 3301. https://doi.org/10.3390/cancers16193301

5. Crisan D., Tarnowietzki E., Bernhard L. et al. Rationale for Using High-Frequency Ultrasound as a Routine Examination in Skin Cancer Surgery: A Practical Approach. J. Clin. Med. 2024; 13 (7): 2152. https://doi.org/10.3390/jcm13072152

6. Austin E., Wang J.Y., Ozog D.M. et al. Photodynamic Therapy: Overview and Mechanism of Action. J. Am. Acad. Dermatol. 2025: S0190-9622(25)00321-4. https://doi.org/10.1016/j.jaad.2025.02.037

7. Wang J.Y., Zeitouni N., Austin E. et al. Photodynamic Therapy: Clinical Applications in Dermatology. J. Am. Acad. Dermatol. 2025: S0190-9622(25)00322-6. https://doi.org/10.1016/j.jaad.2024.12.050

8. Canti G., De Simone A., Korbelik M. Photodynamic therapy and the immune system in experimental oncology. Photochem. Photobiol. Sci. 2002; 1 (1): 79–80. https://doi.org/10.1039/b107764g

9. Płocka M., Czajkowski R. High-frequency ultrasound in the diagnosis and treatment of skin neoplasms. Postepy Dermatol. Alergol. 2023; 40 (2): 204–207. https://doi.org/10.5114/ada.2023.127638

10. Boostani M., Wortsman X., Pellacani G. et al. Dermoscopy-guided high-frequency ultrasound for preoperative assessment of basal cell carcinoma lateral margins: a pilot study. Br. J. Dermatol. 2025; 193 (3): 572–574. https://doi.org/10.1093/bjd/ljaf209

11. Szalai K., Tóth K., Hársing J. et al. High-Frequency Ultrasound Assessment of Basal Cell Carcinoma: Correlations Between Histopathological Subtype, Vascularity, and Age/Sex Distribution. Cancers (Basel). 2026; 18 (2): 274. https://doi.org/10.3390/cancers18020274

12. Feng M.C., Liang J.F., Chen Y.X. et al. Construction of an Aggressiveness Diagnostic Model for Basal Cell Carcinoma Using Multimodal Ultrasound Features. J. Ultrasound Med. 2025; 44 (10): 1839–1848. https://doi.org/10.1002/jum