THE USE OF ULTRASONOGRAPHY IN THE LOCALIZATION OF THE LUMPECTOMY CAVITY FOR INTERSTITIAL BRACHYTHERAPY OF THE BREAST

Purpose: To determine the value of breast ultrasonography (US) in defi ning the lumpectomy cavity for patients treated with interstitial brac hytherapy. Methods and Materials: In March 1993, a protocol of low dos e rate (LDR) interstitial brachytherapy as the sole radiation modality in selected patients with early breast cancer was initiated at Willia m Beaumont Hospital. To date, 60 patients have been entered in this pr otocol, and 38 have undergone US assisted placement of interstitial br achytherapy needles. The lumpectomy cavity was outlined in all dimensi ons and corresponding skin marks were placed for reference at time of implantation, These US dimensions were compared to the physician's cli nical estimate of the location of the lumpectomy cavity, the patient's presurgical mammogram, and the position of the surgical scar, In the intraoperative setting, the dimensions of the lumpectomy cavity were a lso obtained and the placement of the deep plane of interstitial needl es was verified by US. Results: The full extent of the lumpectomy cavi ty was underestimated by clinical examination (physical exam, operativ e report, mammographic information and location of the surgical scar) in 33 of 38 patients (87%). The depth to the chest wall was also incor rectly estimated in 34 (90%) patients when compared to US examination, Intraoperatively, US was performed in nine patients and was useful in verifying the accurate placement of the deepest plane of interstitial brachytherapy needles. In 7 of 9 patients (75%), clinical placement o f needles did not ensure adequate coverage of the posterior extent of the lumpectomy cavity as visualized by intraoperative US. Conclusions: In breast cancer patients considered for interstitial brachytherapy, US appears to be a more accurate means of identifying the full extent of the lumpectomy cavity when compared to clinical estimates, In addit ion, US allows real-time verification of needle placement in the intra operative setting. (C) 1997 Elsevier Science Inc.