Automatic segmentation of MRI in prospective breast volume evaluation: Comparison of different assessments for immediate breast reconstruction.

BACKGROUND: Assessment of breast volume is essential in preoperative planning of immediate breast reconstruction (IBR) surgery to achieve satisfactory cosmetic outcome. This study introduced a breast volume measurement tool that can be used to perform automatic segmentation of magnetic resonance images (MRI) and calculation of breast volume. We compared the accuracy and reliability of this measurement method with four other conventional modalities. METHODS: Patients who were scheduled to undergo mastectomy with IBR between 2016 and 2021 were enrolled in the study. Five different breast volume assessments, including automatic segmentation of MRI, manual segmentation of MRI, 3D surface imaging, mammography, and the BREAST-V formula, were used to evaluate different breast volumes. The results were validated using water displacement volumes of the mastectomy specimens. RESULTS: In this pilot study, a total of 50 female patients met the inclusion criteria and contributed 54 breast specimens to the volumetric analysis. There was a strong linear association between the MRI and water displacement methods (automatic segmentation: r = 0.911, p < 0.001; manual segmentation: r = 0.924, p < 0.001), followed by 3D surface imaging (r = 0.858, p < 0.001), mammography (r = 0.841, p < 0.001), and Breast-V formula (r = 0.838, p < 0.001). Breast volumes measured using automatic and manual segmentation of MRI had lower mean relative errors (30.3% ± 22.0% and 28.9% ± 19.8, respectively) than 3D surface imaging (38.9% ± 31.2), Breast-V formula (44.8% ± 25.8), and mammography (60.3% ± 37.6). CONCLUSION: Breast volume assessment using the MRI methods had better accuracy and reliability than the other methods used in our study. Breast volume measurement using automatic segmentation of MRI could be more efficient compared to the conventional methods.

Accuracy of the Application of 3-Dimensional Printing Models in Orbital Blowout Fractures-A Preliminary Study.

BACKGROUND: Application of 3-dimensional (3D) printing technology has grown in the medical field over the past 2 decades. In managing orbital blowout fractures, 3D printed models can be used as intraoperative navigators and could shorten the operational time by facilitating prebending or shaping of the mesh preoperatively. However, a comparison of the accuracy of computed tomography (CT) images and printed 3D models is lacking. MATERIAL AND METHODS: This is a single-center retrospective study. Patients with unilateral orbital blowout fracture and signed up for customized 3D printing model were included. Reference points for the 2D distance were defined (intersupraorbital notch distance, transverse horizontal, sagittal vertical, and anteroposterior axes for orbital cavity) and measured directly on 3D printing models and on corresponding CT images. The difference and correlation analysis were conducted. RESULTS: In total, 9 patients were reviewed from June 2017 to December 2020. The mean difference in the intersupraorbital notch measurement between the 2 modules was -0.14 mm (P = 0.67). The mean difference in the distance measured from the modules in the horizontal, vertical, and anteroposterior axes of the traumatic orbits was 0.06 mm (P = 0.85), -0.23 mm (P = 0.47), and 0.51 mm (P = 0.32), whereas that of the unaffected orbits was 0.16 mm (P = 0.44), 0.34 mm (P = 0.24), and 0.1 mm (P = 0.88), respectively. Although 2D parameter differences (<1 mm) between 3D printing models and CT images were discovered, they were not statistically significant. CONCLUSIONS: Three-dimensional printing models showed high identity and correlation to CT image. Therefore, personalized models might be a reliable tool of virtual surgery or as a guide in realistic surgical scenarios for orbital blowout fractures.

The symmetry indices of malar mounds for zygomatic bone fracture management based on a computed tomographic model.

BACKGROUND: To date, plastic surgeons do not have an objective method of measuring facial symmetry for zygomatic bone fracture management. Based on clinical practice, the authors utilized a 3-dimensional (3D) model to propose the symmetry index from the anterior view (SIAV) and the symmetry index from inferior view (SIIV). This study aimed to assess the application of these 2 indices. METHODS: The SIAV is defined as the distance between the superior and lower orbital rims (DSLOR) of the defective side divided by that of the healthy side in the anterior view. The SIIV is defined as the area within the region of interest (AROI) of the defective side divided by that of the healthy side in the inferior view. We retrospectively reviewed 95 patients who underwent zygomatic fracture surgery at our medical center from January 2017 to September 2020. The Patients who had bilateral zygomatic fractures and did not have both pre- and postoperative computed tomography (CT) images were excluded. RESULTS: Five out of the 95 patients were enrolled in this study. The difference between pre- and postoperative mean AROI and DSLOR on the healthy side was not significant. The insignificant difference indicates the repeatability of the measurement of the 3D skull model and different CT machines would not affect the calculation of AROI and DSLOR. The mean values of postoperative SIAV (1.06 ± 0.07) and SIIV (1.02 ± 0.08) were closer to 1 than the preoperative values (0.97 ± 0.09 and 1.10 ± 0.12). Although the difference was not statistically significant, the SIIV and SIAV would numerically present the changes in malar bone fracture postoperatively. CONCLUSION: The SIAV and SIIV based on clinical practice could numerically assess the symmetry of the malar mound.

Printing a patient-specific instrument guide for skull osteoma management.

BACKGROUND: To surgically remove osteoma and to keep an optimal cosmetic profile would be very challenging. To solve the difficulty, we utilized the three-dimensional (3D) printing technologies in generating a patient-specific instrument guide (PSIG) for the safe removal of a skull bone tumor. METHODS: The preoperational brain computed tomography (CT) provided the digital imaging with thin slices, and then images were reconstructed into a 3D skull model. Based on the model, we designed a PSIG to make landmarks on the osteoma to avoid excessive removal of the skull bone. During the operation, the surgeons could remove the osteoma piece by piece by using the landmark as a reference point. RESULTS: The PSIG was successfully applied to remove an osteoma that measured 60 × 48 × 40 mm over the left frontoparietal skull of a female patient. The 3D CT reconstruction taken both before and 4 months after surgery showed a significant change in the appearance of the osteoma. CONCLUSION: The PSIG was able to guide the surgeon in the safe removal of the skull osteoma, as well as in maintaining the cosmetic skull profile.

Preoperative breast volume evaluation of one-stage immediate breast reconstruction using three-dimensional surface imaging and a printed mold.

BACKGROUND: Accurate assessment of breast volume is an essential component of preoperative planning in one-stage immediate breast reconstruction (IBR) for achieving breast symmetry and a satisfactory cosmetic outcome. In this study, we compared breast volume estimation using three-dimensional (3D) surface imaging with magnetic resonance imaging (MRI) to determine the accuracy of breast volume measurements. Further, a 3D printing mold for facilitating autologous breast reconstruction intraoperatively is described. METHODS: Patients scheduled to therapeutic or prophylactic mastectomy with one-stage IBR, either by autologous tissue transfer or direct implant, from 2016 to 2019, were enrolled in this study. 3D surface image and MRI were performed to evaluate breast volume and shape. The results were validated by the water displacement volume of the mastectomy specimen. Finally, a 3D printing mold was designed for breast reconstruction with autologous tissue. RESULTS: Nineteen women who were scheduled to have 20 mastectomies (18 unilateral and one bilateral) were included. There was a strong linear association between breast volume measured using the two different methods and water displacement of mastectomy specimens when a Pearson correlation was used (3D surface image: r = 0.925, p < 0.001; MRI: r = 0.915, p < 0.001). Bland-Altman plots demonstrated no proportional bias between the assessment methods. The coefficient of variation was 52.7% for 3D surface imaging and 59.9% for MRI. The volume of six breasts was evaluated by both measurements and the intraclass correlation coefficient was 0.689 for 3D surface image (p = 0.043) and 0.743 for MRI (p = 0.028). CONCLUSION: Using 3D surface image to evaluate breast shape and volume is a quick, effective, and convenient method. The accuracy, reproducibility, and reliability of 3D surface imaging were comparable with MRI in our study. In addition, 3D-printed molds can achieve better symmetry and aesthetic outcomes in immediate autologous breast reconstructions.

Printing a 3-dimensional, Patient-specific Splint for Wound Immobilization: A Case Demonstration.

Three-dimensional (3D) printing technology can generate objects in almost any shape and geometry. This technique also has clinical applications, such as the fabrication of specific devices based on a patient's anatomy. A demonstration study is presented of a 54-year-old man who needed a thermoplastic splint to limit arm movement while a dehisced left shoulder wound healed. The patient's upper extremity was scanned using the appropriate noncontact scanner and 3D technology software, and the polylactic acid splint was printed over the course of 66 hours. This patient-specific splint was worn during the day, and after 2 weeks the wound was healed sufficiently to permit hospital discharge. Creation of an individualized splint is one of many potential medical uses of 3D technology. Although the lengthy printing time imposes limitations, the implications for practice are positive.