Patient-specific 3D Research Articles

Estimation of the Cartilage Volume Loss Due to Knee Osteoarthritis - Case Study

Osteoarthritis (OA) is a degenerative disease of the knee joint caused by the formation of cracks within the collagen fibers of the articular cartilage. Current research is directed towards less invasive procedures for treating this degenerative disease using tissue engineering and 3D bioprinting. Therefore, it is crucial to obtain the exact shape of the damaged tissue, reconstruct the original shape of the tissue, and estimate the volume and area resulting from the wear of the contact surfaces. The study used the tibial plateau of a patient with OA that was removed during total knee arthroplasty, and the data was collected using a 3D scanner. After the reconstruction of the tibial plateau, an assessment of the area and volume of wear on the medial condyle of the tibia was performed, along with a FEM analysis of the real and approximate shape of the cartilage tissue. In this way, it is possible to simulate and create a patient-specific 3D model with a reconstructed wear volume, which can be highly attractive for future treatment strategies for cartilage damage or early stages of OA.

Assessment of the flow-diverter efficacy for intracranial aneurysm treatment considering pre- and post-interventional hemodynamics

Endovascular treatment of intracranial aneurysms with flow diverters (FD) has become one of the most promising interventions. Due to its woven high-density structure they are particularly applicable for challenging lesions. Although several studies have already conducted realistic hemodynamic quantification of the FD efficacy, a comparison with morphologic post-interventional data is still missing. This study analyses the hemodynamics of ten intracranial aneurysm patients treated with a novel FD device. Based on pre- and post-interventional 3D digital subtraction angiography image data, patient-specific 3D models of both treatment states are generated applying open source threshold-based segmentation methods. Using a fast virtual stenting approach, the real stent positions available in the post-interventional data are virtually replicated and both treatment scenarios were characterized using image-based blood flow simulations. The results show FD-induced flow reductions at the ostium by a decrease in mean neck flow rate (51%), inflow concentration index (56%) and mean inflow velocity (53%). Intraluminal reductions in flow activity for time-averaged wall shear stress (47%) and kinetic energy (71%) are present as well. However, an intra-aneurysmal increase in flow pulsatility (16%) for the post-interventional cases can be observed. Patient-specific FD simulations demonstrate the desired flow redirection and activity reduction inside the aneurysm beneficial for thrombosis formation. Differences in the magnitude of hemodynamic reduction exist over the cardiac cycle which may be addressed in a clinical setting by anti-hypertensive treatment in selected cases.

3D-Printed Models for Multidisciplinary Discussion of Congenital Heart Diseases

Background. Congenital heart defects (CHDs) are complex three-dimensional (3D) lesions with variable anatomies that present therapeutic challenges. The application of a patient-specific3D-printed model in preoperative planning and communication in medical practice can contribute to a complete understanding of the intracardiac and vascular anatomy. This study aimed to prospectively investigate the clinical value of a 3D CHD model in multidisciplinary discussions. Methods. Between August 2019 and April 2021, 19 patients with complex CHDs before surgery were prospectively enrolled in this study. Eight to 14 medical specialists participated in multidisciplinary discussions using patient-specific 3D models. A subjective satisfaction questionnaire, comprising 12 questions to be answered on a 10-point scale, was distributed. Results. Twenty 3D-printed anatomic models of 19 patients were used. The median age and weight of the enrolled patients were 0.8 years (range, 5 days to 43 years) and 9.6 kg (range, 2.8–54 kg), respectively. The most common underlying disease was a double outlet of the right ventricle. The mean scores for understanding spatial orientation, ease of communication between clinicians during discussions, prediction of surgical complications, and information additional to conventional 2D imaging were 9.4 ± 1.1, 9.4 ± 0.9, 9.0 ± 1.1, and 9.2 ± 0.4, respectively. The competency and comfort scores for each patient’s surgical plan increased significantly after using the 3D-printed model (from 6.2 ± 1.6 to 9.2 ± 0.9, p < 0.001 and from 6.3 ± 1.6 to 9.2 ± 0.8, p < 0.001, respectively). Conclusions. Patient-specific 3D models, for patients with complex CHDs, improved the understanding of the disease and facilitated multidisciplinary discussions and surgical decision-making. However, because outcomes were mainly evaluated by subjective reports, the possibility of other unknown factors affecting the outcomes should be considered. Trial Registration. This trial is registered with D-1904-031-1024.

Do Osteochondroplasty Alone, Intertrochanteric Derotation Osteotomy, and Flexion-Derotation Osteotomy Improve Hip Flexion and Internal Rotation to Normal Range in Hips With Severe SCFE? - A 3D-CT Simulation Study.

Severe slipped capital femoral epiphysis (SCFE) leads to femoroacetabular impingement and restricted hip motion. We investigated the improvement of impingement-free flexion and internal rotation (IR) in 90 degrees of flexion following a simulated osteochondroplasty, a derotation osteotomy, and a combined flexion-derotation osteotomy in severe SCFE patients using 3D-CT-based collision detection software. Preoperative pelvic CT of 18 untreated patients (21 hips) with severe SCFE (slip-angle>60 degrees) was used to generate patient-specific 3D models. The contralateral hips of the 15 patients with unilateral SCFE served as the control group. There were 14 male hips (mean age 13±2y). No treatment was performed before CT. Specific collision detection software was used for the calculation of impingement-free flexion and IR in 90 degrees of flexion and simulation of osteochondroplasty, derotation osteotomy, and combined flexion-derotation osteotomy. Osteochondroplasty alone improved impingement-free motion but compared with the uninvolved contralateral control group, severe SCFE hips had persistently significantly decreased motion (mean flexion 59±32 degrees vs. 122±9 degrees, P <0.001; mean IR in 90 degrees of flexion -5±14 degrees vs. 36±11 degrees, P <0.001). Similarly, the impingement-free motion was improved after derotation osteotomy, and impingement-free flexion after a 30 degrees derotation was equivalent to the control group (113± 42 degrees vs. 122±9 degrees, P =0.052). However, even after the 30 degrees derotation, the impingement-free IR in 90 degrees of flexion persisted lower (13±15 degrees vs. 36±11 degrees, P <0.001). Following the simulation of flexion-derotation osteotomy, mean impingement-free flexion and IR in 90 degrees of flexion increased for combined correction of 20 degrees (20 degrees flexion and 20 degrees derotation) and 30 degrees (30 degrees flexion and 30 degrees derotation). Although mean flexion was equivalent to the control group for both (20 degrees and 30 degrees) combined correction, the mean IR in 90 degrees of flexion persisted decreased, even after the 30 degrees combined flexion-derotation (22±22 degrees vs. 36 degrees±11, P =0.009). Simulation of derotation-osteotomy (30 degrees correction) and flexion-derotation-osteotomy (20 degrees correction) normalized hip flexion for severe SCFE patients, but IR in 90 degrees of flexion persisted slightly lower despite significant improvement. Not all SCFE patients had improved hip motion with the performed simulations; therefore, some patients may need a higher degree of correction or combined treatment with osteotomy and cam-resection, although not directly investigated in this study. Patient-specific 3D-models could help individual preoperative planning for severe SCFE patients to normalize the hip motion. III, case-control study.

Three-Dimensional Morphometry of the Canine Pelvis: Implications for Total Hip Replacement Surgery.

Two-dimensional measurements of acetabular geometry are widely used for the assessment of acetabular component orientation following total hip replacement (THR). With the increasing availability of computed tomography scans, there is an opportunity to develop three-dimensional (3D) planning to improve surgical accuracy. The aim of this study was to validate a 3D workflow for measuring angles of lateral opening (ALO) and version, and to establish reference values for dogs. Pelvic computed tomography scans were obtained from 27 skeletally mature dogs with no radiographic evidence of hip joint pathology. Patient-specific 3D models were built, and ALO and version angles were measured for both acetabula. The validity of the technique was determined by calculating intra-observer coefficient of variation (CV, %). Reference ranges were calculated and data from left and right hemipelves were compared using a paired t-test and symmetry index. Measurements of acetabular geometry were highly repeatable (intra-observer CV 3.5-5.2%, inter-observer CV 3.3-5.2%). Mean (± standard deviation) values for ALO and version angle were 42.9 degrees (± 4.0 degrees) and 27.2 degrees (± 5.3 degrees) respectively. Left-right measurements from the same dog were symmetrical (symmetry index 6.8 to 11.1%) and not significantly different. Mean values of acetabular alignment were broadly similar to clinical THR guidelines (ALO of 45 degrees, version angle of 15-25 degrees), but the wide variation in angle measurements highlights the potential need for patient-specific planning to reduce the risk of complications such as luxation.

Application of and Prospects for 3-Dimensional Printing in Transcatheter Mitral Valve Interventions.

ClinicalTrials.gov Protocol Registration System (NCT02917980).

Severe equinus cavo-varus correction through triplanar tarsectomy and posterior tibial tendon transfer based on 3D-printed biomodel

Surgery for severe equine cavo-varus is complex and must be individualized. The interindividual phenotypic variability demands a personalized planning of each foot to be operated. The study's primary goal was to evaluate the function and satisfaction of a series of patients with severe equinus cavo-varus deformity who underwent a triplanar tarsectomy and transposition of the posterior tibial tendon in a single stage surgery after a patient specific 3D biomodel planning. A series of 12 feet (5 patients bilaterally) operated with this technique was analyzed. The cohort comprised 2 females (28.5 %) and 5 males (71.4 %). The median follow-up time was 38.5 months (interquartile range: 24.75–48.75). The Foot and Ankle Disability Index pre (median 32.85; interquartile range: 20–46) and postsurgery (median 72; interquartile range: 56–75.5) were collected and statistically significant differences were observed (p < 0.002). Furthermore, the main variable evaluated was obtaining a plantigrade stable foot. This was clinically evaluated and was achieved in all patients except 1 patient who presented a residual equinus of 5º. This study shows that triplanar tarsectomy and posterior tibial tendon transfer in a single surgical procedure after patient-specific 3D biomodel planning allows for improved function in patients with severe equinus cavus varus foot deformity.

Patient-Specific 3D-Printed Models in Pediatric Congenital Heart Disease

Three-dimensional (3D) printing technology has become increasingly used in the medical field, with reports demonstrating its superior advantages in both educational and clinical value when compared with standard image visualizations or current diagnostic approaches. Patient-specific or personalized 3D printed models serve as a valuable tool in cardiovascular disease because of the difficulty associated with comprehending cardiovascular anatomy and pathology on 2D flat screens. Additionally, the added value of using 3D-printed models is especially apparent in congenital heart disease (CHD), due to its wide spectrum of anomalies and its complexity. This review provides an overview of 3D-printed models in pediatric CHD, with a focus on educational value for medical students or graduates, clinical applications such as pre-operative planning and simulation of congenital heart surgical procedures, and communication between physicians and patients/parents of patients and between colleagues in the diagnosis and treatment of CHD. Limitations and perspectives on future research directions for the application of 3D printing technology into pediatric cardiology practice are highlighted.

Impact of 3Dprinted models on quantitative surgical outcomes for patients undergoing robotic-assisted radical prostatectomy: a cohort study.

Three-dimensional (3D) printed anatomic models can facilitate presurgical planning by providing surgeons with detailed knowledge of the exact location of pertinent anatomical structures. Although 3D printed anatomic models have been shown to be useful for pre-operative planning, few studies have demonstrated how these models can influence quantitative surgical metrics. To prospectively assess whether patient-specific 3D printedprostate cancer models can improve quantitative surgical metrics in patients undergoing robotic-assisted radical prostatectomy (RARP). Patients with MRI-visible prostate cancer (PI-RADS V2 ≥ 3) scheduled to undergo RARP were prospectively enrolled in our IRB approved study (n = 82). Quantitative surgical metrics included the rate of positive surgical margins (PSMs), operative times, and blood loss. A qualitative Likert scale survey to assess understanding of anatomy and confidence regarding surgical approach was also implemented. The rate of PSMs was lower for the 3D printedmodel group (8.11%) compared to that with imaging only (28.6%), p = 0.128. The 3D printed model group had a 9-min reduction in operating time (213 ± 42min vs. 222 ± 47min) and a 5mL reduction in average blood loss (227 ± 148mL vs. 232 ± 114mL). Surgeon anatomical understanding and confidence improved after reviewing the 3D printed models (3.60 ± 0.74 to 4.20 ± 0.56, p = 0.62 and 3.86 ± 0.53 to 4.20 ± 0.56, p = 0.22). 3D printedprostate cancer models can positively impact quantitativepatient outcomes such as PSMs, operative times, and blood loss in patients undergoing RARP.

Comparison of 3D printing model to 3D virtual reconstruction and 2D imaging for the clinical education of interns in hepatocellular carcinoma: a randomized controlled study.

The clinical education of interns on hepatocellular carcinoma (HCC) is both crucial and difficult in China, even if the education reform has advanced constantly over the years. The value of specific 3D printing model (3DPM) in clinical education of HCC is uncertain, and relevant literatures are very few. This study aimed to explore the effects of a patient-specific 3D printing liver model on the clinical education of HCC. Three laparoscopic hepatectomies were collected. For each case, a 3D virtual reconstruction (3DVR) and 3DPM were created using multi-detector computed tomography (MDCT) data, respectively. A total of 62 interns were randomly assigned to each group (3DPM, 3DVR, and MDCT groups) through a table of random numbers for random grouping. Following lecture-based HCC education, interns in each group selected a corresponding model of HCC. All interns were tested on the hepatic tumor locations, the vessels adjacent to them, surgical planning, and test time using the centesimal system score within 90 min. A questionnaire investigation on the degree of satisfaction, interest, and helpfulness for improving the comprehension ability of liver anatomy and 3D spatial structures was also recorded. The 3DPM group were compared with both 3DVR and MDCT group by theoretical examination scores and questionnaire survey satisfaction to evaluate the effects of 3DPM on the interns' clinical education in HCC. All the interns completed the test and questionnaire. The 3DPM group gained significantly higher scores on the following test contents: indicating the correct tumor location (3DPM vs. 3DVR, MDCT: 36.7±4.8 vs. 33.2±5.8, 26.8±10.0, P=0.03, P<0.01, respectively), accurately identifying the relationship between the tumor and vessels (3DPM vs. 3DVR, MDCT: 37.1±4.6 vs. 31.6±3.7, 30.0±5.8, P<0.01, P<0.01, respectively), and designing appropriate surgical plans (3DPM vs. 3DVR, MDCT: 8±2.7 vs. 4.9±2.7, 5.9±3.8, P<0.01, P=0.04, respectively). The 3DPM group showed a higher degree of satisfaction (86.2%), interest (92.1%), and helpfulness (80.5%) for improving the comprehension ability of liver anatomy and 3D spatial structures. The clinical teaching by utilizing 3DPM can significantly improve the professional theoretical level, strengthen clinical thinking and comprehensive ability, and improve the teaching effects of HCC for medical interns.

Clinical three-dimensional anatomy of the femur considering navigation-aided surgery of total knee arthroplasty in Japanese patients

PurposeFew studies exist regarding sagittal alignment describing femur morphology in navigation-aided surgery. This study investigated the three-dimensional (3D) sagittal femoral alignment of the whole femur. MethodsSeventy-three consecutive patients (59 females, 14 males, mean age: 76.1 years), yielding 140 femurs, were included in this study. A computed-tomography-based patient-specific 3D femur model was used to define a mechanical axis-based reference plane. Proximal and distal femoral axis angles (PFA, DFA) to the reference plane were measured in 3D using custom software. PFA and DFA represent the proximal and distal inclination of the femoral anatomical axis in sagittal plane, respectively. ResultsPFA (10.6 ± 1.5°) was greater than DFA (2.6 ± 1.6°; P < 0.0001). DFA in females (2.3 ± 1.4°) was smaller than in males (3.9 ± 1.7°; P < 0.0001). ConclusionThis is the first report of measurement of femoral sagittal alignment related to both 3D anatomy and decision making of femoral flexion angle using navigation surgery for total knee arthroplasty. This report shows a robust DFA measurement that could be used as a template for femoral implants flexion angle when performing both conventional and navigated total knee arthroplasty.

Comparative study between patient specific titanium plates versus conventional miniplates for treatment of mandibular fractures: Randomized clinical trial

The aim of the study was to evaluate and assess the clinical stability and efficacy of three-dimensional patient-specific computer-guided titanium plates versus conventional mini plates when used for the treatment of mandibular fractures. Patients with isolated mandibular body fractures were assigned randomly into two equal groups. Group I was treated with patient-specific 3D titanium plates and Group II was treated with conventional mini plates. Outcome measurements included patient satisfaction, pain, occlusion, occlusal bite force and fracture gap distance. All parameters were evaluated at one-week and three-month intervals. The operating time was measured during the surgery. A total of 20 patients were included in the study. Group I (n=10) showed higher values of patient satisfaction and lower pain values than Group II (n=10) at both follow-up intervals. The degree of occlusal derangement showed no statistically significant difference between both groups at one week postoperatively, while both groups showed normal occlusion after 3 months. Occlusal bite forces in Group I were significantly higher than Group II at both follow up intervals. The fracture gap distance was statistically insignificant between both groups at both follow up intervals. The operating time was significantly lower for Group I. Within the limitations of the study, it seems that in the treatment of mandibular body fractures patient-specific plates are preferred over conventional mini plates as they provide more stability, higher biting forces and shorter operating time with highly acceptable outcomes and promising results.

The Effect of Digital Three-Dimensional Reality Models on Patient Counseling for Renal Masses.

Patient counseling for treatment of renal masses is complex. It can be difficult for patients to understand their disease and make treatment decisions when being shown standard black-and-white, two-dimensional computed tomography scans or magnetic resonance images. In a telehealth setting, the patient-physician interaction can be even more challenging. We sought to determine the impact of using digital three-dimensional (3D) models during consultation visits for patients with renal masses. Forty-seven patients participating in a consultation visit for renal masses, both in-person and virtual, were shown a digital 3D model comprised of their kidney, renal mass, and key adjacent structures as part of their counseling. Patients then completed a five-question survey to assess the impact of the 3D model on their visit, with a sixth question administered to telehealth patients. Thirty-five patients undergoing telehealth visits and 12 patients seen in-person were shown the digital 3D model and surveyed. Survey results were universally positive, with all Likert scores > 4.7 (1 - 5 scale). There were no differences between the telehealth and in-person groups. Patients noted the digital 3D model made telehealth visits as effective as in-person visits (average Likert score 4.94). Counseling for patients with renal masses can be augmented with patient-specific digital 3D models, leading to increased provider loyalty, lower levels of patient anxiety, and better understanding and shared decision making.

Digital patient-specific 3D model as an objective assessment tool for neurosurgical planning skills

Digital patient-specific 3D model as an objective assessment tool for neurosurgical planning skills

A CFD study on the interplay of torsion and vortex guidance by the mitral valve on the left ventricular wash-out making use of overset meshes (Chimera technique).

Cardiovascular disease often occurs with silent and gradual alterations of cardiac blood flow that can lead to the onset of chronic pathological conditions. Image-based patient-specific Computational Fluid Dynamics (CFD) models allow for an extensive quantification of the flow field beyond the direct capabilities of medical imaging techniques that could support the clinicians in the early diagnosis, follow-up, and treatment planning of patients. Nonetheless, the large and impulsive kinematics of the left ventricle (LV) and the mitral valve (MV) pose relevant modeling challenges. Arbitrary Lagrangian-Eulerian (ALE) based computational fluid dynamics (CFD) methods struggle with the complex 3D mesh handling of rapidly moving valve leaflets within the left ventricle (LV). We, therefore, developed a Chimera-based (overset meshing) method to build a patient-specific 3D CFD model of the beating LV which includes a patient-inspired kinematic model of the mitral valve (LVMV). Simulations were performed with and without torsion. In addition, to evaluate how the intracardiac LV flow is impacted by the MV leaflet kinematics, a third version of the model without the MV was generated (LV with torsion). For all model versions, six cardiac cycles were simulated. All simulations demonstrated cycle-to-cycle variations that persisted after six cycles but were albeit marginal in terms of the magnitude of standard deviation of velocity and vorticity which may be related to the dissipative nature of the numerical scheme used. The MV was found to have a crucial role in the development of the intraventricular flow by enhancing the direct flow, the apical washout, and the propagation of the inlet jet towards the apical region. Consequently, the MV is an essential feature in the patient-specific CFD modeling of the LV. The impact of torsion was marginal on velocity, vorticity, wall shear stress, and energy loss, whereas it resulted to be significant in the evaluation of particle residence times. Therefore, including torsion could be considered in patient-specific CFD models of the LV, particularly when aiming to study stasis and residence time. We conclude that, despite some technical limitations encountered, the Chimera technique is a promising alternative for ALE methods for 3D CFD models of the heart that include the motion of valve leaflets.

Toward New Assessment of Knee Cartilage Degeneration.

Assessment of human joint cartilage is a crucial tool to detect and diagnose pathological conditions. This exploratory study developed a workflow for 3D modeling of cartilage and bone based on multimodal imaging. New evaluation metrics were created and, a unique set of data was gathered from healthy controls and patients with clinically evaluated degeneration or trauma. We present a novel methodology to evaluate knee bone and cartilage based on features extracted from magnetic resonance imaging (MRI) and computed tomography (CT) data. We developed patient specific 3D models of the tibial, femoral, and patellar bones and cartilages. Forty-seven subjects with a history of degenerative disease, traumatic events, or no symptoms or trauma (control group) were recruited in this study. Ninety-six different measurements were extracted from each knee, 78 2D and 18 3D measurements. We compare the sensitivity of different metrics to classify the cartilage condition and evaluate degeneration. Selected features extracted show significant difference between the 3 groups. We created a cumulative index of bone properties that demonstrated the importance of bone condition to assess cartilage quality, obtaining the greatest sensitivity on femur within medial and femoropatellar compartments. We were able to classify degeneration with a maximum recall value of 95.9 where feature importance analysis showed a significant contribution of the 3D parameters. The present work demonstrates the potential for improving sensitivity in cartilage assessment. Indeed, current trends in cartilage research point toward improving treatments and therefore our contribution is a first step toward sensitive and personalized evaluation of cartilage condition.

Methacrylated Silk Fibroin Additive Manufacturing of Shape Memory Constructs with Possible Application in Bone Regeneration.

Methacrylated silk (Sil-MA) is a chemically modified silk fibroin specifically designed to be crosslinkable under UV light, which makes this material applicable in additive manufacturing techniques and allows the prototyping and development of patient-specific 2D or 3D constructs. In this study, we produced a thin grid structure based on crosslinked Sil-MA that can be withdrawn and ejected and that can recover its shape after rehydration. A complete chemical and physical characterization of Sil-MA was first conducted. Additionally, we tested Sil-MA biocompatibility according to the International Standard Organization protocols (ISO 10993) ensuring the possibility of using it in future trials. Sil-MA was also tested to verify its ability to support osteogenesis. Overall, Sil-MA was shown to be biocompatible and osteoconductive. Finally, two different additive manufacturing technologies, a Digital Light Processing (DLP) UV projector and a pneumatic extrusion technique, were used to develop a Sil-MA grid construct. A proof-of-concept of its shape-memory property was provided. Together, our data support the hypothesis that Sil-MA grid constructs can be injectable and applicable in bone regeneration applications.

A Computational Study of Blood Flow Dynamics in the Pulmonary Arteries

In this work we study the blood dynamics in the pulmonary arteries by means of a 3D-0D geometric multiscale approach, where a detailed 3D model for the pulmonary arteries is coupled with a lumped parameters (0D) model of the cardiovascular system. We propose to investigate three strategies for the numerical solution of the 3D-0D coupled problem: the Splitting-Explicit and Implicit algorithms, where information are exchanged between 3D and 0D models at each time step at the interfaces, and the One-Way algorithm, where the 0D is solved first off-line. In our numerical experiments performed in a realistic patient-specific 3D domain with a physiologically calibrated 0D model, we discuss first the issue on instabilities that may arise when not suitable connections are considered between 3D and 0D models; second we compare the performance and accuracy of the three proposed numerical strategies. Finally, we report a comparison between a healthy and a hypertensive case, providing a preliminary result highlighting how our method could be used in future for clinical purposes.

New method to apply the lumbar lordosis of standing radiographs to supine CT-based virtual 3D lumbar spine models

Standing radiographs play an important role in the characterization of spinal sagittal alignment, as they depict the spine under physiologic loading conditions. However, there is no commonly available method to apply the lumbar lordosis of standing radiographs to supine CT-based virtual 3D models of the lumbar spine. We aimed to develop a method for the sagittal rigid-body registration of vertebrae to standing radiographs, using the exact geometry reconstructed from CT-data. In a cohort of 50 patients with monosegmental spinal degeneration, segmentation and registration of the lumbar vertebrae and sacrum were performed by two independent investigators. Intersegmental angles and lumbar lordosis were measured both in CT scans and radiographs. Vertebrae were registered using the X-ray module of Materialise Mimics software. Postregistrational midsagittal sections were constructed of the sagittal midplane sections of the registered 3D lumbar spine geometries. Mean Hausdorff distance was measured between corresponding registered vertebral geometries. The registration process minimized the difference between the X-rays’ and postregistrational midsagittal sections’ lordoses. Intra- and inter-rater reliability was excellent based on angle and mean Hausdorff distance measurements. We propose an accessible, accurate, and reproducible method for creating patient-specific 3D geometries of the lumbar spine that accurately represent spinal sagittal alignment in the standing position.

A 3D-printed surgical guide for ischemic scar targeting and ablation.

3D printing technology development in medical fields allows to create 3D models to assist preoperative planning and support surgical procedures. Cardiac ischemic scar is clinically associated with malignant arrhythmias. Catheter ablation is aimed at eliminating the arrhythmogenic tissue until the sinus rhythm is restored. The scope of this work is to describe the workflow for a 3D surgical guide able to define the ischemic scar and target catheter ablation. For the patient-specific 3D surgical guide and 3D heart phantom model realization, both CT scan and cardiac MRI images were processed; this was necessary to extract anatomical structures and pathological information, respectively. Medical images were uploaded and processed in 3D Slicer. For the surgical guide modeling, images from CT scan and MRI were loaded in Meshmixer and merged. For the heart phantom realization, only the CT segmentation was loaded in Meshmixer. The surgical guide was printed in MED625FLX with Polyjet technology. The heart phantom was printed in polylactide with FDM technology. 3D-printed surgical model was in agreement with prespecified imputed measurements. The phantom fitting test showed high accuracy of the 3D surgical tool compared with the patient-specific reproduced heart. Anatomical references in the surgical guide ensured good stability. Ablation catheter fitting test showed high suitability of the guide for different ablation tools. A 3D-printed guide for ventricular tachycardia ablation is feasible and accurate in terms of measurements, stability, and geometrical structure. Concerning clinical use, further clinical investigations are eagerly awaited.