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Ultrasound Nakagami Imaging to Assess Breast Fibrosis Following Breast-Cancer Radiotherapy

X Yang

X Yang*, M Torres, H Chen, T Liu, Emory Univ, Atlanta, GA

TH-C-217BCD-5 Thursday 10:30:00 AM - 12:30:00 PM Room: 217BCD

Purpose: To investigate ultrasound Nakagami imaging to assess breast fibrosis in women with breast cancer undergoing whole breast radiotherapy (RT).

Methods: Previous studies have demonstrated that the Nakagami-model-based image can characterize scatterers in tissues through ultrasound echo statistics. We hypothesize that the Nakagami image may serve as a functional imaging tool to assess breast fibrosis. To test this concept, we conducted a pilot study with 10 breast-cancer patients. All patients received a standard course of radiation: 50.4 Gy followed by an electron boost of 10.0 Gy at the lumpectomy site. A baseline ultrasound scan was performed one week prior to RT. Two additional scans were performed at 6-month and 12-month post RT. Patients were imaged on both breasts with a 10-MHz ultrasound linear probe, in a supine position, at the 12, 3, 6, and 9 o'clock axes as well as at the lumpectomy site. Scans taken on the untreated breast served as a control. Conventional ultrasound images and radio-frequency (RF) echo signals were acquired simultaneously. The envelopes of backscattered radio-frequency signals were used for Nakagami imaging. The Nakagami parameter image is constructed by using a square sliding window to process the enveloped signals.

Results: Significant changes were observed in Nakagami image parameter values between the treated and untreated breasts. The average Nakagami parameters was 1.02 for the untreated breasts and 1.18 for treated breasts (p<0.001). The increased Nakagami parameter indicates increase in the concentration of local scatterers and the appearance of the periodic structures or clustering of scatterers that would change the backscattering statistics. Such changes may be correlated to the development of fibrosis.

Conclusions: The current findings indicate that the ultrasound Nakagami image has great potential as a functional imaging tool to complement the use of the conventional B-scan to assess radiation-induced breast fibrosis.

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