Prepectoral Dual-Port Tissue Expander Placement: Can This Eliminate Suction Drain Use?

Dosimetric characterization of single- and dual-port temporary tissue expanders for postmastectomy radiotherapy using Monte Carlo methods

Purpose

The aim of this work was two-fold: a) to assess two treatment planning strategies for accounting CT artifacts introduced by temporary tissue-expanders (TTEs); b) to evaluate the dosimetric impact of two commercially available and one novel TTE.

Methods

The CT artifacts were managed using two strategies. 1) Identifying the metal in the RayStation treatment planning software (TPS) using image window-level adjustments, delineate a contour enclosing the artifact, and setting the density of the surrounding voxels to unity (RS1). 2) Registering a geometry template with dimensions and materials from the TTEs (RS2). Both strategies were compared for DermaSpan, AlloX2, and AlloX2-Pro TTEs using Collapsed Cone Convolution (CCC) in RayStation TPS, Monte Carlo simulations (MC) using TOPAS, and film measurements. Wax slab phantoms with metallic ports and breast phantoms with TTEs balloons were made and irradiated with a 6 MV AP beam and partial arc, respectively. Dose values along the AP direction calculated with CCC (RS2) and TOPAS (RS1 and RS2) were compared with film measurements. The impact in dose distributions was evaluated with RS2 by comparing TOPAS simulations with and without the metal port.

Results

For the wax slab phantoms, the dose differences between RS1 and RS2 were 0.5% for DermaSpan and AlloX2 but 3% for AlloX2-Pro. From TOPAS simulations of RS2, the impact in dose distributions caused by the magnet attenuation was (6.4 ± 0.4) %, (4.9 ± 0.7)%, and (2.0 ± 0.9)% for DermaSpan, AlloX2, and AlloX2-Pro, respectively. With breast phantoms, maximum differences in DVH parameters between RS1 and RS2 were as follows. For AlloX2 at the posterior region: (2.1 ± 1.0)%, (1.9 ± 1.0)% and (1.4 ± 1.0)% for D1, D10, and average dose, respectively. For AlloX2-Pro at the anterior region (-1.0 ± 1.0)%, (-0.6 ± 1.0)% and (-0.6 ± 1.0)% for D1, D10 and average dose, respectively. The impact in D10 caused by the magnet was at most (5.5 ± 1.0)% and (-0.8 ± 1.0)% for AlloX2 and AlloX2-Pro, respectively.

Conclusion

Two strategies for accounting for CT artifacts from three breast TTEs were assessed using CCC, MC, and film measurements. This study showed that the highest differences with respect to measurements occurred with RS1 and can be mitigated if a template with the actual port geometry and materials is used.

Toward Drainless Breast Reconstruction: A Pilot Study

Implant-based breast reconstruction with immediate tissue expander placement is the predominant form of breast reconstruction in the United States. Closed-suction drains are frequently employed to minimize seroma accumulation, although they carry the risk of serving as a port of entry for bacteria, posing a concern in the presence of implanted materials such as breast implants or acellular dermal matrix. Introduction of a dual-port tissue expander designed to facilitate the collection and removal of seroma fluid provides a new way of performing breast reconstruction without external drains.

Methods

We conducted a pilot study using the AlloX2 dual-port expander on five consecutive patients to demonstrate feasibility of this approach at Cedars-Sinai Medical Center by the two senior authors (E.R. and D.K.).

Results

Patients averaged seven clinic visits before they were ready for expander exchange, totaling a mean of 137.5 days. Patients averaged 1.9 clinic visits before output was less than 40cm³ (1.6 for right breasts and 2.2 for left breasts), with two of the patients never reaching that output. There was one complication; a single patient had unilateral flap necrosis and implant exposure due to excessively large breasts and thin skin flaps, necessitating expander removal and latissimus flap reconstruction. The other four patients underwent successful implant reconstruction.

Conclusions

This pilot study demonstrates the feasibility of breast reconstruction without external drains using a dual-port expander with built-in seroma reservoir. From these results, it is apparent that dual-port tissue expanders with built-in seroma reservoir offer a safe and effective way to perform breast reconstruction without drains in appropriately selected patients. A larger prospective cohort will be needed to definitively demonstrate lower infection and reconstructive failure rates.

Evaluation of Dual-port versus Single-port Tissue Expanders in Postmastectomy Breast Reconstruction

Background

Immediate tissue expander placement in postmastectomy breast reconstruction can be complicated by seroma or infection, requiring further imaging studies or interventions. This study compares dual-port tissue expanders, with both an aspiration and expansion port, with single-port expanders in terms of postoperative complications and further interventions.

Methods:

Patients with immediate tissue expander placement from March 2019 to March 2020 were reviewed. Complications included seroma, infection, hematoma, necrosis, and malposition of the expander. Further intervention included aspiration, ultrasound imaging, interventional radiology (IR) drainage, or return to operating room.

Results:

In total, 128 dual-port expanders were compared with 125 single-port expanders. Patients with single-port expanders were younger (P = 0.022) and of lower BMI (P = 0.01). There were no significant differences in key complications between these groups. In multivariate analysis, single-port expanders had a 3.4× higher odds of postoperative ultrasound imaging when controlling for texture, placement, and age (P = 0.01). Mean time to IR drain placement in the dual-port group was approximately 30 days after placement in single port (51.1 versus 21.4 days, P = 0.013). Thirty-four percent of dual-port expanders had at least one aspiration in clinic performed by plastic surgery, versus 2% of single port that required ultrasound-guided aspiration (P < 0.001).

Conclusions:

There were no differences in key postoperative complications between the two expander cohorts. Dual-port expanders significantly reduced postoperative ultrasound imaging, and delayed IR drain placement. The added convenience of clinic aspirations likely reduced costs related to utilization of resources from other departments.