Surgeon-performed ultrasound reliably predicts skin spacing and may decrease the rate of MammoSite balloon catheter explantation in patients undergoing brachytherapy for breast cancer

ObjectiveThe purpose of this study was to determine if the distance from the skin to the seroma cavity, as measured with ultrasound (US) before catheter placement, correlated with the distance from skin to MammoSite balloon catheter as measured on computerized axial tomography (CAT) after catheter placement.MethodsUS was used to measure the distance from the skin to the seroma cavity, and then the MammoSite balloon catheter was inserted. Skin-to-balloon distance was then measured using CAT. Statistical analysis was performed to determine correlation between the 2 measurements.ResultsOur cohort consisted of 70 patients. US distance correlated with CAT distance (Pearson correlation coefficient .70). Mean US distance was 10.8 mm (SD 4.5 mm); mean CAT distance was 11.9 mm (SD 7.5 mm); and mean difference between the 2 measurements was –1.1 mm (SD 6.1 mm). A US measurement ≥7.6 mm predicted successful completion of MammoSite brachytherapy in 98% of patients. Patients with skin-to-seroma cavity distance <7.6 mm required explantation before treatment completion 39% of the time.ConclusionsOffice-based US performed before insertion of the MammoSite balloon catheter statistically correlates with measurement by CAT. Patients with ≥7.6 mm skin-to-seroma cavity distance on US had a higher completion rate of MammoSite brachytherapy treatment.