Transfer Learning via Artificial Intelligence for Guiding Implant Placement in the Posterior Mandible: an in vitro Study

Background: To explore the capacity of a single shot multibox detector (SSD) and Voxel-to-voxel prediction network for pose estimation (V2V-PoseNet) based artificial intelligence (AI) system in automatically designing implant plan. Methods: 2500 and 67 cases were used to develop and pre-train the AI system. After that, 12 patients who missed the mandibular left first molars were selected to test the capacity of the AI in automatically designing implant plan. There were three algorithms-based implant positions. They are Group A, B and C (8, 9 and 10 points dependent implant position, respectively). The AI system was then used to detect the characteristic annotators and determine the implant position. For every group, the actual implant position was compared with the algorithm-determined ideal position. And global, angular, depth and lateral deviation were calculate. One-way ANOVA followed by Tukey’s test was performed for statistical comparisons. The significance value was set at P< 0.05. Results: Group C represented the least coronal (0.6638±0.2651, range: 0.2060 to 1.109 mm) and apical (1.157±0.3350, range: 0.5840 to 1.654 mm) deviation, the same trend was observed in the angular deviation (5.307 ±2.891°, range: 2.049 to 10.90°), and the results are similar with the traditional statistic guide.Conclusion: It can be concluded that the AI system has the capacity of deep learning. And as more characteristic annotators be involved in the algorithm, the AI system can figure out the anatomy of the object region better, then generate the ideal implant plan via deep learning algorithm.

Thermal Effects during Bone Preparation and Insertion of Osseointegrated Transfemoral Implants

Background: The preparation of bone for the insertion of an osseointegrated transfemoral implant and the insertion process are performed at very low speeds in order to avoid thermal damages to bone tissue which may potentially jeopardize implant stability. The aim of this study was to quantify the temperature increase in the femur at different sites and insertion depths, relative to the final implant position during the stepwise implantation procedure. Methods: The procedure for installation of the osseointegrated implant was performed on 24 femoral specimens. In one specimen of each pair, the surgery was performed at the clinically practiced speed, while the speed was doubled in the contralateral specimen. Six 0.075 mm K fine gauge thermocouples (RS Components, Sorby, UK) were inserted into the specimen at a distance of 0.5 mm from the final implant surface, and six were inserted at a distance of 1.0 mm. Results: Drilling caused a temperature increase of <2.5 °C and was not statistically significantly different for most drill sizes (0.002 < p < 0.845). The mean increase in temperature during thread tapping and implant insertion was <5.0 °C, whereas the speed had an effect on the temperature increase during thread tapping. Conclusions: Drilling is the most time-consuming part of the surgery. Doubling the clinically practiced speed did not generate more heat during this step, suggesting the speed and thus the time- and cost-effectiveness of the procedure could be increased. The frequent withdrawal of the instruments and removal of the bone chips is beneficial to prevent temperature peaks, especially during thread tapping.

Quality Control after Intracochlear Intralabyrinthine Schwannoma Resection and Cochlear Implantation

Background: The combination of intralabyrinthine schwannoma (ILS) removal and cochlear implantation is the standard of care after surgical resection for audiological rehabilitation. Intracochlear ILS is not only the most frequent tumor in this group of schwannomas, but it is also, to some degree, surgically the most challenging because of its position behind the modiolus. Recent developments in the knowledge of implant position, implant magnet choice, and magnetic resonance imaging (MRI) sequences make an MRI follow-up after surgical removal possible. Thus far, no results are known about the surgical success and residual rate of these kind of tumors. The aim of the present study was to perform an early MRI follow-up for the evaluation of residual or recurrent intracochlear ILS after surgical removal and cochlear implantation. Methods: In a retrospective study, we evaluated seven patients after an intracochlear ILS removal and single-stage cochlear implantation with a mean period of 13.4 months post surgery with a 3T T1 GAD 2 mm sequence for a residual ILS. Patients were operated on using an individualized technique concept. Results: In six out of seven cases, 3 T T1 GAD 2 mm MRI follow-up showed no residual or recurrent tumor. In one case, a T1 signal indicated a tumor of the upper inner auditory canal (IAC) at the MRI follow up. Conclusion: MRI follow-up as a quality control tool after ILS removal and cochlear implantation is highly important to exclude residual tumors. Long-term MRI evaluation results are needed and can be obtained under consideration of implant position, implant magnet, and MRI sequence choice. A preoperative MRI slice thickness less than 2 mm can be recommended to visualize possible modiolar and IAC expansion.

Modified Breast Band Improving the Postoperative Breast Augmentation and Reconstructive Experience

Superior displacement of implants is a common complication in the early postoperative period following breast augmentation surgery. Postoperative breast bands are used during the first 4 weeks to optimize breast implant position following breast augmentation and reconstructive procedures. Although currently available breast bands are effective in maintaining implants in an inferior position, they have been observed to irritate the armpit region. We hypothesized that a modified breast band geometry with cut outs to accommodate the armpit region would provide equal maintenance of desired implant position while providing improved postoperative comfort. Forty patients who underwent breast augmentation and/or reconstruction were randomly assigned to receive either the traditional breast band or the modified cut out designed breast band following surgery for 4 weeks. Patients rated their breast bands on a 1 to 10 scale regarding (1) comfort, (2) appearance, and (3) overall satisfaction at their routine postoperative visits at 1, 2, and 4 weeks following surgery. The modified breast band scored higher for all factors at 1, 2, and 4 weeks following surgery. The traditional band demonstrated decreasing scores for comfort and overall satisfaction when compared at 4 weeks versus 1 week. There was no change in the modified breast band scores for comfort, appearance, nor overall satisfaction over the same time period. This study of 40 patients found that the modified band provides equally effective maintenance of implants in a desired position without compromising comfort and appearance. Patients who used the modified band had a better experience with the band comfort, appearance, and overall satisfaction in comparison to the traditional band. The higher ratings for the cut out band for comfort, appearance, and overall satisfaction were consistent from week 1 to 4. In contrast, the traditional band not only scored lower in comfort, appearance, and overall satisfaction compared to the modified band but also demonstrated significant decrease in the patients’ ratings for comfort and overall satisfaction for the traditional band from week 1 to 4. This study supports the conclusion that a modified cut out breast band design provides an equally effective maintenance of implants in a desired position without compromising comfort, appearance, and overall satisfaction when compared to the traditional band.

CBCT image artefacts generated by implants located inside the field of view or in the exomass

Objectives: To compare artefacts in cone-beam computed tomography (CBCT) arising from implants of different materials located either inside the field-of-view (FOV) or in the exomass, and to test different image-acquisition parameters to reduce them. Methods: CBCT scans of a human mandible prepared with either a titanium, titanium-zirconium, or zirconia implant were acquired with the Planmeca ProMax utilizing FOV sizes of 8 × 5 cm and 4 × 5 cm, which placed the implant inside the FOV (8 × 5 cm) or in the exomass (4 × 5 cm). The scanning parameters considered three conditions of metal artefact reduction (MAR), disabled, low, and high, and two kVp levels (80 and 90). The standard deviation (SD) of grey values of regions of interest was obtained. The effects of implant material, implant position, MAR condition, kVp level, and their interactions were evaluated by Analysis of Variance (α = 5%). Results: The zirconia implant produced the highest SD values (more heterogeneous grey values, corresponding to greater artefact expression), followed by titanium-zirconium, and titanium. In general, implants in the exomass produced images with higher SD values than implants inside the FOV. MAR was effective in decreasing SD values, especially from the zirconia implant, only when the implant was inside the FOV. Images with 80 kVp had higher SD values than those with 90 kVp, regardless of the other factors (p < 0.05). Conclusions: Implants in the exomass lead to greater artefact expression than when they are inside the FOV. Special attention should be paid to scanning parameters that reduce metal-related artefacts, such as MAR activation and increasing kVp. This is especially important with a zirconia implant inside the FOV.

Intraoperative Computed Tomography Image Fusion for Orbital Blowout Fracture Reconstruction

Intraoperative computed tomography (CT) has been previously described and acknowledged for its use in orbital blowout fracture reconstructions. We described a clinical case series managed by this technique combined with intraoperative image fusion for accuracy in orbital implant position. In total, eight patients who sustained a total number of 19 orbital wall fractures were described. From the total number of 19 blowout orbital fracture reconstructions comprised of medial and inferior (floor) orbital fractures, malposition was identified in a total of four orbital implants by using image fusion. All cases of implant malposition were immediately revised intraoperatively. Subsequent fusion was carried out to confirm whether the revision was satisfactorily achieved. We found that the intraoperative image fusion technique utilised to determine orbital implant position, especially at the posterior ledge, further augmented the role of intraoperative CT scanning. Image fusion conceptually provides an immediate, real-time, and objective solution for intraoperative image analysis and potentially eliminates problems with misaligned CT images. It also reduces the need for the surgeon to ‘eye-ball’ the CT images acquired or the need for additional intraoperative time, since the patient’s head orientation is always axially at random during the acquisition of the CT. Conventional methods for CT image assessment are subjected to one’s own interpretation and may introduce inconsistent or longer intraoperative decision-making. The technique facilitates intraoperative decision-making and reduces the risk of orbital implant malposition in orbital blowout fracture reconstructions. Hence, surgical complication in relation to orbital implant malposition in orbital blowout fracture management could be minimised. In addition, no further postoperative imaging is required.