Implications of a New Generation of Tissue Expanders for Post-Mastectomy Radiotherapy in Breast Reconstruction: A...

Background: Tissue expanders with metallic ports are commonly used in post-mastectomy breast reconstruction but can produce significant computed tomography (CT) artifacts, which impair accurate delineation of target volumes during radiotherapy planning. The Motiva Flora^® expander incorporates an integrated radiofrequency identification (RFID) valve, designed to be magnet-free and magnetic resonance imaging (MRI)-conditional, potentially minimizing image distortion and improving the precision of treatment planning. This pilot study aims to quantitatively compare the extent of CT image distortion observed in radiotherapy simulation scans between conventional metallic-valve expanders and RFID-valve expanders, evaluating their impact on radiotherapy planning quality. Methods: Between January 2024 and September 2025, fourteen consecutive patients who underwent post-mastectomy two-stage breast reconstruction followed by adjuvant RT at Hospital Santa Maria della Misericordia (Udine, Italy) were included. Seven patients received Motiva Flora^® tissue expanders with a non-metallic RFID port, and seven received Mentor CPX4^® expanders with a conventional metallic port. The volume of areas with a significant level of artifacts (artifact volume) was quantitatively evaluated by delineating the CT image area of distortion caused by the valve. Moreover, a comparison of the ratio between artifact volume and clinical target volume (artifact volume/CTV volume) between expander types to assess potential imaging-related distortions has been made. Group comparisons of volume ratio were performed using Welch's t-test. Results: Patients reconstructed with Motiva Flora^® showed a mean artifact volume of 24.5 ± 10.3 cc, whereas those with Mentor CPX4^® expanders presented a mean artifact volume of 64.2 ± 38.1 cc. The ratio between artifact volume and clinical target volume (CTV) was lower in patients reconstructed with Motiva expanders compared to those reconstructed with Mentor expanders and this difference was significant with Welch's t-test (p = 0.046). Conclusions: The reduced CT distortion observed with the RFID valve-equipped Motiva Flora suggests a superior radiological compatibility compared to conventional metallic-port expanders, with potential to enhance the accuracy of radiotherapy planning.