Estimation of implant size based on mammograms in immediate breast reconstruction

Background Implant size selection is a critical component of preoperative planning for immediate breast reconstruction. This paper introduces a novel formula, based on preoperative mammograms, for estimating implant volume in patients undergoing immediate breast reconstruction. Methods A retrospective analysis of 115 consecutive patients with immediate breast reconstruction following skin or nipple sparing mastectomy was performed. A calculated implant size was obtained using the formula, calculated implant size (ml) = π × height (cm) × [base width (cm) − 3]. The calculations were performed independently by two surgeons and based on the ipsilateral preoperative mammogram. The calculated implant size was compared with the actual implant size used during the surgery and results were analysed. Results The mean calculated and actual implant sizes were 376.03 ml and 324.49 ml, respectively. There was no difference found between calculated and actual implant sizes ( t = − 1.704, p = 0.090), and there was a strong positive correlation between calculated and actual implant sizes ( r = 0.7748, p < 0.00001). Further analysis revealed greater accuracy of the formula in patients with an estimated implant size of less than 350 ml, and a tendency to overestimate implant size in breasts with an estimated volume of more than 350 ml. Conclusions The mammography-based formula is a simple and practical method to estimate implant size preoperatively. Ultimately, implant selection for the best possible cosmetic outcome is a multifactorial process, of which breast volume is one consideration. This formula can serve as a useful adjunct for preoperative assessment. Level of Evidence: Level III, diagnostic study.