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Background: In the context of guided surgery, augmented reality (AR) represents a groundbreaking improvement. The Video and Optical See-Through Augmented Reality Surgical System (VOSTARS) is a new AR wearable head-mounted display (HMD), recently developed as an advanced navigation tool for maxillofacial and plastic surgery and other non-endoscopic surgeries. In this study, we report results of phantom tests with VOSTARS aimed to evaluate its feasibility and accuracy in performing maxillofacial surgical tasks. Methods: An early prototype of VOSTARS was used. Le Fort 1 osteotomy was selected as the experimental task to be performed under VOSTARS guidance. A dedicated set-up was prepared, including the design of a maxillofacial phantom, an ad hoc tracker anchored to the occlusal splint, and cutting templates for accuracy assessment. Both qualitative and quantitative assessments were carried out. Results: VOSTARS, used in combination with the designed maxilla tracker, showed excellent tracking robustness under operating room lighting. Accuracy tests showed that 100% of Le Fort 1 trajectories were traced with an accuracy of ±1.0 mm, and on average, 88% of the trajectory’s length was within ±0.5 mm accuracy. Conclusions: Our preliminary results suggest that the VOSTARS system can be a feasible and accurate solution for guiding maxillofacial surgical tasks, paving the way to its validation in clinical trials and for a wide spectrum of maxillofacial applications.

Augmented reality (AR) Head-Mounted Displays (HMDs) are emerging as the most efficient output medium to support manual tasks performed under direct vision. Despite that, technological and human-factor limitations still hinder their routine use for aiding high-precision manual tasks in the peripersonal space. To overcome such limitations, in this work, we show the results of a user study aimed to validate qualitatively and quantitatively a recently developed AR platform specifically conceived for guiding complex 3D trajectory tracing tasks. The AR platform comprises a new-concept AR video see-through (VST) HMD and a dedicated software framework for the effective deployment of the AR application. In the experiments, the subjects were asked to perform 3D trajectory tracing tasks on 3D-printed replica of planar structures or more elaborated bony anatomies. The accuracy of the trajectories traced by the subjects was evaluated by using templates designed ad hoc to match the surface of the phantoms. The quantitative results suggest that the AR platform could be used to guide high-precision tasks: on average more than 94% of the traced trajectories stayed within an error margin lower than 1 mm. The results confirm that the proposed AR platform will boost the profitable adoption of AR HMDs to guide high precision manual tasks in the peripersonal space.

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Gross anatomy knowledge is an essential element for medical students in their education, and nowadays, cadaver-based instruction represents the main instructional tool able to provide three-dimensional (3D) and topographical comprehensions. The aim of the study was to develop and test a prototype of an innovative tool for medical education in human anatomy based on the combination of augmented reality (AR) technology and a tangible 3D printed model that can be explored and manipulated by trainees, thus favoring a three-dimensional and topographical learning approach. After development of the tool, called AEducaAR (Anatomical Education with Augmented Reality), it was tested and evaluated by 62 second-year degree medical students attending the human anatomy course at the International School of Medicine and Surgery of the University of Bologna. Students were divided into two groups: AEducaAR-based learning (“AEducaAR group”) was compared to standard learning using human anatomy atlas (“Control group”). Both groups performed an objective test and an anonymous questionnaire. In the objective test, the results showed no significant difference between the two learning methods; instead, in the questionnaire, students showed enthusiasm and interest for the new tool and highlighted its training potentiality in open-ended comments. Therefore, the presented AEducaAR tool, once implemented, may contribute to enhancing students’ motivation for learning, increasing long-term memory retention and 3D comprehension of anatomical structures. Moreover, this new tool might help medical students to approach to innovative medical devices and technologies useful in their future careers.

AimsCardiac resynchronization therapy (CRT) involves time-consuming procedures to achieve an optimal programming of the system, at implant as well as during follow-up, when remodelling occurs. A device equipped with an implantable sensor able to measure peak endocardial acceleration (PEA) has been recently developed to monitor cardiac function and to guide CRT programming. During scanning of the atrioventricular delay (AVD), PEA reflects both left ventricle (LV) contractility (LV dP/dtmax) and transmitral flow. A new CRT optimization algorithm, based on recording of PEA (PEAarea method) was developed, and compared with measurements of LV dP/dtmax, to identify an optimal CRT configuration.Methods and resultsWe studied 15 patients in New York Heart Association classes II–IV and with a QRS duration >130 ms, who had undergone implantation of a biventricular (BiV) pulse generator connected to a right ventricular (RV) PEA sensor. At a mean of 39 ± 15 days after implantation of the CRT system, the patients underwent cardiac catheterization. During single-chamber LV or during BiV stimulation, with initial RV or LV stimulation, and at settings of interventricular intervals between 0 and 40 ms, the AVD was scanned between 60 and 220 ms, while LV dP/dtmax and PEA were measured. The area of PEA curve (PEAarea method) was estimated as the average of PEA values measured during AVD scanning. A ≥10% increase in LV dP/dtmax was observed in 12 of 15 patients (80%), who were classified as responders to CRT. In nine of 12 responders (75%), the optimal pacing configuration identified by the PEAarea method was associated with the greatest LV dP/dtmax.ConclusionThe concordance of the PEAarea method with measurements of LV dP/dtmax suggests that this new, operator-independent algorithm is a reliable means of CRT optimization.

Summary: The CAD/CAM technology for mandibular reconstruction has improved the results in terms of outcomes in restoring mandibular complex defects. Augmented reality (AR) represents an evolution of the navigation-assisted surgery. This technology merges the images of the virtual planning with the anatomy of the patient, representing in this way an enhanced scene for the surgeon’s eye. AR can also display in a single scene additional information for the surgeon. Despite of classical navigation, this scenario can be obtained with marker-less registration method, without using reference points or fiducial markers. This technologic evolution together with the large use in our experience of CAD/CAM protocol for mandibular reconstruction we developed this feasibility study to evaluate the possibility of using a marker-less image registration system. Moreover, we tried to evaluate the overlaying of the virtual planning and its reproducibility using AR. We performed a case series of 3 consecutive patients who underwent mandibular reconstruction using AR-assisted fibular free flap harvesting applying our digital workflow. Once launched, the mobile app installed on our tablet, the registration is performed according to a shape recognition system of the leg of the patient, rendering in real time a superimposition of the anatomy of the bony, vascular, and skin of the patient and also the surgical planning of the reconstruction. AR-assisted fibular free flap harvesting was performed. We believe that AR can be a prospective improving technology for mandibular complex reconstruction.

In orthognathic surgery, the use of patient-specific osteosynthesis devices is a novel approach used to transfer the virtual surgical plan to the patient. The aim of this study is to analyse the quality of mandibular anatomy reproduction using a mandible-first mandibular-PSI guided procedure on 22 patients. Three different positioning guide designs were compared in terms of osteosynthesis plate positioning and mandibular anatomical outcome. PSIs and positioning guides were designed according to virtual surgical plan and 3D printed using biocompatible materials. A CBCT scan was performed 1 month after surgery and postoperative mandibular models were segmented for comparison against the surgical plan. A precision comparison was carried out among the three groups. Correlations between obtained rami and plates discrepancies and between planned rami displacements and obtained rami discrepancies were calculated. Intraoperatively, all PSIs were successfully applied. The procedure was found to be accurate in planned mandibular anatomy reproduction. Different guide designs did not differ in mandibular outcome precision. Plate positional discrepancies influenced the corresponding ramus position, mainly in roll angle and vertical translation. Ramus planned displacement was found to be a further potential source of inaccuracy, possibly due to osteosynthesis surface interference. Computer-assisted designed and manufactured (CAD/CAM) devices-widely known as Patient Specific Implants (PSIs)-have been increasingly adopted for orthognathic surgery, as per recent evidence in Literature of gaining better accuracy for virtual planning transfer to the patient (