What is the value of 3D virtual reality in understanding acetabular fractures?

BACKGROUND: Acetabular fractures are difficult to classify owing to the complex three-dimensional (3D) anatomy of the pelvis. 3D printing helps to understand and reliably classify acetabular fracture types. 3D-virtual reality (VR) may have comparable benefits. Our hypothesis is that 3D-VR is equivalent to 3D printing in understanding acetabular fracture patterns. METHODS: A total of 27 observers of various experience levels from several hospitals were requested to classify twenty 3D printed and VR models according to the Judet-Letournel classification. Additionally, surgeons were asked to state their preferred surgical approach and patient positioning. Time to classify each fracture type was recorded. The cases were randomized to rule out a learning curve. Inter-observer agreement was analyzed using Fleiss' kappa statistics (κ). RESULTS: Inter-observer agreements varied by observer group and type of model used to classify the fracture: medical students: 3D print (κ = 0.61), VR (κ = 0.41); junior surgical residents: 3D print (0.51) VR (0.54); senior surgical residents: 3D print (0.66) VR (0.52); junior surgeons: 3D print (0.56), VR (0.43); senior surgeons: 3D print (κ = 0.59), VR (κ = 0.42). Using 3D printed models, there was more agreement on the surgical approach (junior surgeons κ = 0.23, senior surgeons κ = 0.31) when compared with VR (junior surgeons κ = 0.17, senior surgeons 0.25). No difference was found in time used to classify these fractures between 3D printing and VR for all groups (P = 1.000). CONCLUSIONS: The Judet-Letournel acetabular classification stays difficult to interpret; only moderate kappa agreements were found. We found 3D-VR inferior to 3D printing in classifying acetabular fractures. Furthermore, the current 3D-VR technology is still not practical for intra-operative use.

Influence of involuntary facial expressions on reproducibility of 3D stereophotogrammetry in children with and without complete unilateral cleft lip and palate from 3 to 18 months of age.

OBJECTIVES: To assess the influence of involuntary facial expressions on 3D facial stereophotogrammetry reproducibility in children with and without unilateral cleft lip, alveolus and palate (UCLP) aged 3-18 months. MATERIALS AND METHODS: Three to eight 3D facial images per time point were acquired within 10 min of 31 children with UCLP and 50 controls at 3, 12 and 18 months of age. 3D mapping of two 3D facial images per subject per age was performed. Distance kits of the full face and nasolabial area were calculated. RESULTS: In the total subject pool, mean variation between two 3D facial images ranged from 0.38-0.88 mm. There were no significant differences within groups for the various ages. Variation between controls and UCLP subjects did not differ significantly. Variation was higher in the nasolabial area than in the full face. CONCLUSIONS: The influence of involuntary facial expressions on the estimation of facial growth should not be underestimated, especially in the nasolabial region of UCLP subjects aged 3 months. To improve 3D facial imaging reliability, image capturing should be performed by a trained photographer following a meticulous image capturing protocol, including thorough review after capture. CLINICAL RELEVANCE: Facial 3D stereophotogrammetry is a useful tool for monitoring facial growth longitudinally in young children with facial deformities, as no radiation is involved and image capture is easy and fast. It can be performed reliably in children with and without UCLP aged 3-18 months by an experienced photographer utilising a meticulous image capturing protocol.

Three-Dimensional Imaging of the Face: A Comparison Between Three Different Imaging Modalities.

BACKGROUND: Three-dimensional (3D) imaging of the face is being used extensively in medicine for clinical decision making, surgical planning, and research. Nowadays, several companies are offering a broad range of 3D imaging systems, varying in price, method, and mobility. However, most planning and evaluation methods are created and validated solely with one imaging system. Therefore, it is important to analyze possible differences in the 3D surface reconstruction between different systems. OBJECTIVES: The objective of this study was to analyze differences in the 3D surface reconstruction between three systems: 3dMDface system, Vectra XT, and Artec Eva. METHODS: Three-dimensional images of the face were acquired from 15 healthy patients with each imaging system. Reproducibility of each device was calculated and a comparison of the Vectra XT and Artec Eva with the 3dMDface was made. RESULTS: All 3D imaging devices showed high reproducibility, with a mean difference of 0.18 ± 0.15 mm (3dMDface system), 0.15 ± 0.15 mm (Vectra XT), and 0.26 ± 0.24 mm (Artec Eva). No significant difference in reproducibility was found between the Vectra XT and 3dMDface, while a significant difference was found between 3dMDface and Artec Eva, and between Vectra XT and Artec Eva. The mean difference between 3dMDface and Vectra XT was 0.32 ± 0.26 mm. The mean difference between 3dMDface and Artec Eva was 0.44 ± 1.09 mm. CONCLUSIONS: All three imaging devices showed high reproducibility and accuracy. Although the Artec Eva showed a significant lower reproducibility, the difference found was not clinically relevant. Therefore, using these different systems alongside each other in clinical and research settings is possible.

3D Facial Effects of a Simulated Dental Build-up.

OBJECTIVE: The purpose of this study was to evaluate the 3D-stereophotogrammetry technique to detect differences in facial appearance after a simulated rehabilitation. MATERIALS AND METHODS: Eleven volunteers without tooth wear participated. A 3D-stereophotograph was taken in five different situations: resting position, teeth in occlusion, and teeth in occlusion with a 1 mm-, 3 mm- or 5 mm resin block between the first molars. Cephalometric measurements were performed on the 3D-stereophotographs using the software program Maxilim® (Medicim NV Mechelen, Belgium). Four anatomical parameters were analyzed: (1) Subnasale-Gnathion, (2) Subnasale-Stomion, (3) Stomion-Gnathion, and (4) Masseter right-Masseter left. A paired Student's T-test was applied to detect significant differences (p < 0.05). RESULTS: Statistically significant changes in facial appearance of the lower facial height were detected in all measured positions, teeth in occlusion, 1 mm-, 3 mm-, and 5 mm block (p < 0.05). For the main distance (Subnasale-Gnathion) the mean measured differences were, respectively, 3.2 mm; 5.2 mm; and 6.7 mm. CONCLUSIONS: With 3D-stereophotograph imaging technology, it was possible to detect changes in facial appearance after an artificial increase of vertical dimension of occlusion. This finding implies that reconstruction of loss of tooth substance may cause a visible change in facial appearance of the patient. CLINICAL SIGNIFICANCE: This study reveals a new 3D imaging technique that may be used for a better and more comprehensive treatment planning in patients with severe tooth wear. (J Esthet Restor Dent 28:397-404, 2016).

Virtual Incision Pattern Planning using Three-Dimensional Images for Optimization of Syndactyly Surgery.

Syndactyly is a congenital condition characterized by fusion of the fingers. If not treated correctly during infancy, syndactyly may hinder the normal development of hand function. Many surgical techniques have been developed, with the main goal to create a functional hand with the smallest number of operative corrections. Therefore, exact preoperative planning of the reconstructive procedure is essential. An imaging method commonly used for preoperative planning is 3-dimensional (3D) surface imaging. The goal of this study was to implement the use of this technique in hand surgery, by designing a virtual planning tool for a desyndactylization procedure based on 3D hand images. A 3D image of a silicon syndactyly model was made on which the incision pattern was virtually designed. A surgical template of this pattern was printed, placed onto the silicon model and delineated. The accuracy of the transfer from the virtual delineation toward the real delineation was calculated, resulting in a mean difference of 0.82 mm. This first step indicates that by using 3D images, a virtual incision pattern can be created and transferred back onto the patient successfully in an easy and accurate way by using a template. Thereafter, 3D hand images of 3 syndactyly patients were made, and individual virtual incision patterns were created. Each pattern was transferred onto the patient by using a 3D printed template. The resulting incision pattern needed minor modifications by the surgeon before the surgery was performed. Further research and validation are necessary to develop the virtual planning of desyndactylization procedures.

Accuracy of Three Software Applications for Breast Volume Calculations from Three-Dimensional Surface Images.

BACKGROUND: Knowing breast volumes before certain surgeries helps the surgeon to obtain breast symmetry. Calculating breast volumes from three-dimensional surface images is possible with specialized software applications. However, limited data exist concerning the accuracy of such volume calculations. The purpose of this study was to investigate the accuracy of breast volume calculations performed with the 3D BreAST, 3dMD Vultus, and VECTRA software applications. METHODS: Twenty-six subjects who underwent 44 mastectomies were enrolled. Preoperative three-dimensional surface images were acquired with a VECTRA-XT stereophotogrammetry device. Breast volumes were calculated from these images with the three software applications. The mastectomy specimens were weighed to derive their actual volume and compared with the software calculations. RESULTS: For all three methods, a positive correlation between the breast volume and absolute calculation error was found (p < 0.001), but not for the errors as a percentage of the breast volume (p = 0.17, p = 0.80, and p = 0.42). The 3D BreAST, 3dMD Vultus, and VECTRA applications provided mean volume calculation errors of 21, 186, and -32 ml (p = 0.27, p < 0.001, and p = 0.14) or 2 ± 25, 48 ± 26, and -6 ± 27 percent of the breast volume (p = 0.67, p < 0.001, and p = 0.16), respectively. CONCLUSIONS: Despite that two applications calculated accurate mean breast volumes, all applications showed a high standard deviation in terms of the percentage of the breast volume. Therefore, the usefulness of absolute breast volume calculations from three-dimensional surface images seems limited. CLINICAL QUESTION/LEVEL OF EVIDENCE: Diagnostic, II.

The facial effects of tooth wear rehabilitation as measured by 3D stereophotogrammetry.

OBJECTIVE: Evaluate the effect of a full rehabilitation, including an increase of vertical dimension of occlusion (VDO), in patients with severe tooth wear on changes in facial appearance. METHODS: Patients with severe tooth wear were restoratively treated using direct composite restorations, including an increase of the VDO. Before and one month after treatment 3D stereophotographs were taken and facial changes were measured with the use of 3D cephalometric landmarks. Cast models were used to determine the Tooth Wear Index (TWI) and the VDO-increase. The Orofacial Esthetic Scale-questionnaire was used to evaluate subjective happiness with appearance. Paired Student's t-tests were used to evaluate the changes after full rehabilitation. The relation between the facial changes, VDO-increment and TWI-score were analyzed using multiple regression models (p < 0.05). RESULTS: 44 Patients (35 men, 9 women, mean age: 38.2 ±â€¯7.1 y) participated in this study. Mean TWI-score at baseline was 3.3 ±â€¯0.5 and the mean increase in VDO was 1.6 ±â€¯0.9 mm. Lower face height increased by 1.9 mm (p ≤ 0.001). Patients reported a significant improvement in orofacial appearance: OES-summary score of 34.3 ±â€¯11.2 before and 59.9 ±â€¯6.8 one month after treatment (p < 0.001). The increase of VDO resulted in an increase in Lower Face Height (p ≤ 0.002), whereas the TWI-score at baseline had no effect on the facial changes. The applied increase in VDO and TWI-score were not related to changes in OES-scores. CONCLUSIONS: A full rehabilitation with an increase in VDO resulted in objective differences in facial height as measured with 3D stereophotogrammetry. CLINICAL SIGNIFICANCE: In patients with severe tooth wear, receiving a full rehabilitation including an increase in vertical dimension of occlusion, an objectively change will occur in the Lower facial height, but this effect will be subjectively judged as a positive change.

Patient-Specific Actual-Size Three-Dimensional Printed Models for Patient Education in Glioma Treatment: First Experiences.

BACKGROUND: Patients with cancer need high-quality information about disease stage, treatment options, and side effects. High-quality information can also improve health literacy, shared decision making, and satisfaction. We created patient-specific three-dimensional (3D) models of tumors including surrounding functional areas and assessed what patients with glioma value (or fear) about the models when they are used to educate them about the relationship between their tumor and specific brain parts, the surgical procedure, and risks. METHODS: This exploratory study included adult patients with glioma who underwent functional magnetic resonance imaging and diffusion tensor imaging as part of preoperative work-up. All participants received an actual-size 3D model printed based on functional magnetic resonance imaging and diffusion tensor imaging. Semistructured interviews were conducted to identify facilitators and barriers for using the model and perceived effects. RESULTS: Models were successfully created for all 11 participants. There were 18 facilitators and 8 barriers identified. The model improved patients' understanding about their situation; patients reported that it was easier to ask their neurosurgeon questions based on their model and that it supported their decision about preferred treatment. A perceived barrier for using the 3D model was that it could be emotionally confronting, particularly in an early phase of the disease. Positive effects were related to psychological domains, including coping, learning effects, and communication. CONCLUSIONS: Patient-specific 3D models are promising and simple tools that could help patients with glioma better understand their situation, treatment options, and risks. These models have the potential to improve shared decision making.

Single-Step Resection of an Intraosseous Meningioma and Cranial Reconstruction: Technical Note.

OBJECTIVE: Simultaneous tumor resection and cranial reconstruction can be a challenging task. Surgical navigation is an indispensable tool in making this single-step procedure possible. In this technical note, we describe a new technique for this procedure to ensure a precise resection and optimal fit of the implant in a patient with an intraosseous meningioma. METHODS: We generated a 3-dimensional (3D) model of the patient's skull based on a computed tomography scan and created a digital "resection line" object using 3D Studio Max 2016 software. Based on this object, the patient-specific implant was generated and printed with a 3D printer. Before surgery, the digital object was transferred to the neuronavigation system to enable a navigated resection of the lesion to ensure maximum precision. During surgery, the craniotomy was performed, and the custom-made implant was fitted in a single step. RESULTS: The planned resection was achieved, and the implant could be fitted without need for further adjustments to the resection border. CONCLUSIONS: We provide a simple technique to digitally define a planned resection site and create a custom-made implant using specialized software and 3D printing to enable single-step resection of a skull lesion and cranial reconstruction, thereby reducing surgical time and costs and ensuring a good cosmetic result.

3D stereophotogrammetry in upper-extremity lymphedema: An accurate diagnostic method.

BACKGROUND: Upper-extremity lymphedema is a frequent complication in patients treated for breast cancer. Current diagnostic methods for the upper-extremity volume measurements are cumbersome or time consuming. The purpose of this study was to assess the validity and reliability of three-dimensional (3D) stereophotogrammetry for volume measurements in patients with upper-extremity lymphedema. METHOD: Patients with unilateral upper-extremity lymphedema were included. The water displacement volume measurement of both arms was performed using a standardized method. In addition, 3D stereophotogrammetry volume measurements were conducted. RESULTS: Eleven patients (22 arms) were included. The mean volumes obtained by 3D stereophotogrammetry and water displacement show a high correlation, with a Pearson's correlation coefficient of 0.99 (p = 0.01). The variance calculated by 3D stereophotogrammetry measurements (205 mL) was statistically significant less than that obtained via water displacement measurements (1540 mL) (p < 0.001). CONCLUSION: 3D stereophotogrammetry is an accurate method for measuring upper-extremity volume in patients with lymphedema and gives a lower variance value compared to that of the water displacement measurements. We recommend the use of this method in the diagnosis and follow-up of patients with lymphedema.

Accuracy of virtually 3D planned resection templates in mandibular reconstruction.

OBJECTIVE: Since reconstruction of composite defects in the head and neck region is a challenging and demanding problem for head and neck surgeons, surgical aids have been sought for decades. The purpose of this study was to evaluate the accuracy of prefabricated surgical resection templates used in mandibular segmental resections in comparison to the virtual surgical plan. MATERIALS AND METHODS: A prospective study was performed in 11 consecutive patients, with a primary T4 oral squamous cell carcinoma or osteoradionecrosis of the mandible. Preoperatively, a CBCT scan was acquired to delineate the size and extension of tumor invasion; a virtual patient-specific resection template was designed based on this information. Intraoperatively, the resection template was positioned on the mandible and secured using four fixation screws. Postoperatively, a CBCT scan was acquired. This scan was superimposed on the preoperative scan. Positioning of the resection template and inclination of the resection planes were evaluated on the virtual head model. In order to test the interobserver reliability of these new measurement methods, two different observers executed all measurements. RESULTS: The mean shift of the proximal resection templates was 3.76 mm (standard deviation [SD] 3.10 mm). For the distal resection templates, the mean shift was 3.06 mm (SD 1.57 mm) with no significant interobserver difference (ICC = 0.99). An absolute mean deviation of 8.5° (SD 5.3°) was found for the proximal resection angle and 10.4° (SD 5.0°) for the distal resection angle. Again, no significant interobserver differences were found (ICC = 0.98). CONCLUSION: The resection templates used in this study proved reasonably accurate. Although the concept of virtual surgical planning aids significantly in mandibular reconstruction with microvascular free flaps, further improvement of resection accuracy is necessary for further improvement of reconstruction accuracy.