3D Computed Tomography Scan Research Articles

From bench to bedside: 3D reconstruction and printing as a valuable tool for the chest wall surgeon

Background/purposeThe development of computer-aided design/manufacturing and digital image technology shows promise to revolutionize several medical and surgical fields. In this context, we propose a different approach for minimally invasive repair of pectus excavatum (MIRPE) including preoperative planning, ambulatory template fitting, and implant customization. MethodsWe prospectively collected data on 130 consecutive patients who underwent a novel process of implant customization for MIRPE between November 2015 and September 2019 at our institution. This process consisted of: 1) preoperative planning using 3D computed tomography scan reconstruction and 3D printing of the implant template, 2) an ambulatory fitting session with the template, and 3) manufacture of a custom made, prebent, metallic implant based on the 3D printed templates. We described the process in detail and analyzed the “implant-deformity” match, need for rebending, modification of the curvature or shape of the pectus implant intraoperatively, and accuracy of the number of bars planned preoperatively. ResultsPreoperative planning including 3D reconstruction and printing resulted in a 92.3% optimal “implant-deformity” anatomic match. Minimal rebending without flipping of the implants was required in 5.4% of the patients. In two cases (1.5%), the implants were too short, and they tended to sink into the intercostal space, and in one case (0.8%), the patient's chest was extremely asymmetric, and the implant had to be removed and rebent intraoperatively. The number of implants planned preoperatively was precise in 100%. ConclusionsIn this study, we demonstrated that minimally invasive repair of pectus excavatum assisted by preoperative planning, ambulatory template fitting, and implant customization enables an excellent anatomic match, leading to minimal rebending, and avoiding implant flipping or removal after retrosternal passage as well as accuracy in the number of bars programmed preoperatively. Type of studyProspective registry. Level of evidenceIII.

Protecting the Heart: A Practical Approach to Account for the Full Extent of Heart Motion in Radiation Therapy Planning

Emerging evidence suggests that the heart is more radiosensitive than previously assumed; therefore, accounting for heart motion in radiation therapy planning is becoming more critical. In this study, we determined how much heart delineations based on 3-dimensional (3D) computed tomography (CT), 4-dimensional (4D) average projection (AVG), and maximum intensity projection (MIP) images should be extended to represent the full extent of heart motion during 4D imaging acquisition. The 3D and 4D CT scans of 10 lung cancer patients treated with stereotactic ablative radiation therapy were used. Median surfaces were derived from heart delineations of 3 observers on the 3D CT, AVG, MIP, and 25% exhale scans. Per patient, the 25% exhale contour was propagated on every phase of the 4D scan. The union of all 4D phase delineations (U4D) represented the full extent of heart motion during imaging acquisition. Surface distances from U4D to 3D, AVG, and MIP volumes were calculated. Distances in the most extreme surface points (1.5 cm most superoinferior, 10% most right/left/anteroposterior) were used to derive margins accounting only for systematic (delineation) errors. Heart delineations on the MIP were the closest to the full extent of motion, requiring only ≤2.5-mm margins. Delineations on the AVG and 3D scans required margins up to 3.4 and 7.1 mm, respectively. The largest margins were for the inferior, right, and anterior aspects for the delineations on the 3D, AVG, and MIP scans, respectively. Delineations on 3D, AVG, or MIP scans required extensions for representing the heart's full extent of motion, with the MIP requiring the smallest margins. Research including daily imaging to determine the random components for the margins and dosimetric measurements to determine the relevance of creating a planning organ at risk volume of the heart is required.

Early experience of single level full endoscopic posterior cervical foraminotomy and comparison with microscope-assisted open surgery.

Posterior cervical foraminotomy (PCF) is one of the standard surgeries for treatment of cervical spondylotic radiculopathy. Full endoscopic application for PCF has recently applied to minimize traumatization of the surgical access. Here we present our early experience of full endoscopic PCF (FEPCF) and compared with results of microscope-assisted open PCF (OPCF) surgery. Seven cases of one level FEPCF were carried out during March and November of 2019, and seven cases of previously performed one level OPCF were included for comparison in this study. Operating time, foraminotomy area calculating from postoperative reconstructed 3D-computed tomography (3D-CT) scan, improvement of Oswestry neck disability index (ONDI) at 1 month after surgery, and use of postoperative PRN medication were compared. Mann-Whitney's U-test was used for statistical analysis. Operating time of FEPCF and OPCF was 70.9 and 85.0 min respectively and not statistically different (P=0.37). Foraminotomy area of FEPCF was 51.67 cm2, significantly smaller than that of OPCF of 93.47 cm2 (P=0.025). Improvement of ONDI 1 month after surgery was not significantly different (50.4% for FEPCF and 41.0% for OPCF, P=0.72). Use of postoperative PRN pain medication was significantly less in FEPCF, 0.57 times as compared with OPCF, 8.71 times (P=0.0022). One level FEPCF is as effective as OPCF in alleviation of radiculopathy related symptoms and requires similar operating time as OPCF. In addition, FEPCF significantly reduces foraminotomy area requires for nerve root decompression, and use of postoperative pain medication compared with OPCF. FEPCF is technically feasible and considered as less invasive treatment options for cervical spondylotic radiculopathy as compared with OPCF.

A three-dimensional computed tomography study to determine the ideal method for fluoroscopically-guided bone marrow aspiration from the iliac crest.

Bone marrow aspiration (BMA) through the iliac crest is potentially unsafe due to the vicinity of neurovascular structures in the greater sciatic notch. Our objective was to investigate the safety of a recently described BMA technique, specifically a trajectory from the posterior superior iliac spine (PSIS) to the anterior inferior iliac spine (AIIS). We conducted a chart review of 260 patients, analyzing three-dimensional (3D) reconstructed computed tomography (CT) images of the pelvis and sacrum to validate that this new approach offers a wide safety margin from the greater sciatic notch. Analysis of 3D CT scans demonstrated that the PSIS to AIIS trajectory never crossed the greater sciatic notch. The trajectory was noted to be at least one cm away from the greater sciatic notch in all measurements. The new trajectory entered the PSIS at 25.29 ± 4.34° (left side) and 24.93 ± 4.15° (right side) cephalad from the transverse plane, and 24.58 ± 4.99° (left side) and 24.56 ± 4.67° (right side) lateral from the midsagittal plane. The area of bone marrow encountered with the new approach was approximately 22.5 cm2. Utilizing the same CT scans, the trajectory from the traditional approach crossed the greater sciatic notch in all scans, highlighting the potential for violating the greater sciatic notch boundary, and damaging important neurovascular structures. Statistically, significant sex-related differences were identified in needle trajectory angles for both approaches. We conclude that based on this 3D CT study, a trajectory from the PSIS to the AIIS for BMA may offer a wide safety margin from the greater sciatic notch.

Correlation of Intracranial Volume With Head Surface Volume in Patients With Multisutural Craniosynostosis.

Intracranial volume (ICV) is an important parameter for monitoring patients with multisutural craniosynostosis. Intracranial volume measurements are routinely derived from computed tomography (CT) head scans, which involves ionizing radiation. Estimation of ICV from head surface volumes could prove useful as 3D surface scanners could be used to indirectly acquire ICV information, using a non-invasive, non-ionizing method.Pre- and postoperative 3D CT scans from spring-assisted posterior vault expansion (sPVE) patients operated between 2008 and 2018 in a single center were collected. Patients were treated for multisutural craniosynostosis, both syndromic and non-syndromic. For each patient, ICV was calculated from the CT scans as carried out in clinical practice. Additionally, the 3D soft tissue surface volume (STV) was extracted by 3D reconstruction of the CT image soft tissue of each case, further elaborated by computer-aided design (CAD) software. Correlations were analyzed before surgery, after surgery, combined for all patients and in syndrome subgroups.Soft tissue surface volume was highly correlated to ICV for all analyses: r = 0.946 preoperatively, r = 0.959 postoperatively, and r = 0.960 all cases combined. Subgroup analyses for Apert, Crouzon-Pfeiffer and complex craniosynostosis were highly significant as well (P < 0.001).In conclusion, 3D surface model volumes correlated strongly to ICV, measured from the same scan, and linear equations for this correlation are provided. Estimation of ICV with just a 3D surface model could thus be realized using a simple method, which does not require radiations and therefore would allow closer monitoring in patients through multiple acquisitions over time.

P63 Mutation Impacts the Structure of Cardiopharyngeal Field Derived Muscles in Mice

The cardiopharyngeal field (CPF) includes anterior lateral mesoderm of the first heart field and the contiguous pharyngeal mesoderm. The latter gives rise to second‐heart‐field‐derived heart regions and branchiomeric head muscles. Neural crest cells (NCCs) surround and infiltrate mesoderm cells, forming connective tissue of head and heart musculature. NCCs are also involved in the septation of the cardiac outflow tract, the patterning of pharyngeal arch arteries, and in the proper development of attachments of branchiomeric muscles to skull, jaw, hyoid bone, and laryngeal cartilages.The p63 (aka Trp63) transcription factor is essential for the differentiation of epithelial tissue (ectoderm and endoderm) during embryogenesis. To form the correct amount of mature ectodermal, mesodermal, and NCC populations and to control the differentiation of the CPF, p63 interacts with downstream transcription factors, such as Tbx1, Isl1, and nkx2.5. We analyzed how the loss of p63 expression in p63−/− mice affected the mesodermal derivatives of the CPF. We hypothesized that the loss of p63 decreases the number of mesodermal cells differentiating from the CPF, causing a smaller mesodermal cell population in the CPF. We expected to see smaller CPF derived muscles in the p63 mutant mice, as well as deficient connective tissue in head and heart musculature as well as weakened attachments of craniofacial muscles.To determine if and when certain muscular defects appear, we performed muscle antibody staining and dissected wildtype littermates and p63−/− mice (B6.129S7‐Trp63tm2Brd/J strain) aged embryonic day (E) 12–18. We have collected minimum of five specimens for each age. We studied craniofacial, laryngeal, as well as cardiac musculature by analyzing the antibody stained specimens under the microscope and by performing microdissections under a stereomicroscope. We used 3D computed tomography scan images (taken with a uCT scanner, Skyscan 1172) to compare the craniofacial skeletons between wildtype and mutant mice.In p63−/− mice, branchiomeric muscles such as the masseter, buccinator, and nasolabialis were properly attached to bony elements but were smaller than what was seen in the wildtype mice. The p63−/− head is flexed and the chin is closer to the chest than in the wildtype specimens: this posture could be caused by the shortened and less dense sternocleidomastoid muscle in the p63−/− mice. Corresponding with previous reports, our p63 −/− mice also showed several malformations (e.g., poorly developed limbs, cleft palate, cardiac abnormalities) stereotypical of this mouse mutant and which are also seen in humans with p63 mutations such as in ADULT (acro‐dermatoungual‐lacrimal‐tooth) and EEC (Ectrodactyly‐Ectodermal Dysplasia‐Cleft Lip /Palate) syndromes. Despite that p63 expression is restricted to epithelium, the described defects reveal that p63 expression is important to much earlier, and shared developmental processes, notably NCC proliferation and differentiation, that do impact tissues derived from mesoderm as well as from epithelium. Analyzing the influence of p63 on CPF differentiation will contribute to a better understanding of regulatory mechanisms during head and heart development including the role of these mechanisms in human congenital syndromes.

A fast graph-based algorithm for automated segmentation of subcutaneous and visceral adipose tissue in 3D abdominal computed tomography images

The aim of the study was to create an accurate method of automated subcutaneous (SAT) and visceral (VAT) adipose tissue detection basing on three-dimensional (3D) computed tomography (CT) scans.One hundred and forty abdominal CT examinations were analysed. An algorithm for automated detection of SAT and VAT consisted of following steps: thresholding of an analysed image, detection of a patient’s body region, separation of SAT and VAT. The algorithm was sequentially applied to each 2D axial slice of a 3D examination. To assess the accuracy of the proposed method, automated and manual segmentations (performed by two readers) of SAT and VAT were compared using Dice similarity coefficient (DSC) and average Hausdorff distance (AHD).Mean DSC was equal to 99.6% ± 0.4% for SAT and 99.6% ± 0.5% for VAT, which was equal to DSC obtained for comparison between both readers. In 90% of cases DSC was equal or above 99.0% and the minimal DSC was 97.6%. AHD equalled to 0.04 ± 0.06 for SAT and 0.13 ± 0.23 for VAT (automated vs. manual segmentations), while AHD for comparison of two manual segmentations was 0.03 ± 0.07 for SAT and 0.09 ± 0.20 for VAT. The processing time for a single slice was 0.16 s for an automated segmentation and 5−10 min for a manual segmentation. The processing time of an entire 3D stack (around 40 2D slices) was on average 6.5 s.Our algorithm for the automated detection of SAT and VAT on 3D CT scans has the same accuracy as manual segmentation and performs equally well for both adipose tissue compartments.

Comparative Analysis of Surgical Outcomes of C1–2 Fusion Spine Surgery between Intraoperative Computed Tomography Image Based Navigation-Guided Operation and Fluoroscopy-Guided Operation

ObjectiveFixation of the C1–2 segment is challenging because of the complex anatomy in the region and the need for a high degree of accuracy to avoid complications. Preoperative 3D-computed tomography (CT) scans can help reduce the risk of complications in the vertebral artery, spinal cord, and nerve roots. However, the patient may be susceptible to injury if the patient’s anatomy does not match the preoperative CT scans. The intraoperative 3D image-based navigation systems have reduced complications in instrument-assisted techniques due to greater accuracy. This study aimed to compare the radiologic outcomes of C1–2 fusion surgery between intraoperative CT image-guided operation and fluoroscopy-guided operation. MethodsWe retrospectively reviewed the radiologic images of 34 patients who underwent C1–2 fusion spine surgery from January 2009 to November 2018 at our hospital. We assessed 17 cases each of degenerative cervical disease and trauma in a study population of 18 males and 16 females. The mean age was 54.8 years. A total of 139 screws were used and the surgical procedures included 68 screws in the C1 lateral mass, 58 screws in C2 pedicle, nine screws in C2 lamina and C2 pars screws, four lateral mass screws in sub-axial level. Of the 34 patients, 19 patients underwent screw insertion using intraoperative mobile CT. Other patients underwent atlantoaxial fusion with a standard fluoroscopy-guided device. ResultsA total of 139 screws were correctly positioned. We analyzed the positions of 135 screws except for the four screws that performed the lateral mass screws in C3 vertebra. Minor screw penetration was observed in seven cases (5.2%), and major pedicle screw penetration was observed in three cases (2.2%). In one case, the malposition of a C2 pedicle screw was confirmed, which was subsequently corrected. There were no complications regarding vertebral artery injury or onset of new neurologic deficits. The screw malposition rate was lower (5.3%) in patients who underwent intraoperative CT-based navigation than that for fluoroscopy-guided cases (10.2%). And we confirmed that the operation time can be significantly reduced by surgery using intraoperative O-arm device. ConclusionSpinal navigation using intraoperative cone-beam CT scans is reliable for posterior fixation in unstable C1-2 pathologies and can be reduced the operative time.

Location of Intra- and Extra-articular Hip Impingement Is Different in Patients With Pincer-Type and Mixed-Type Femoroacetabular Impingement Due to Acetabular Retroversion or Protrusio Acetabuli on 3D CT–Based Impingement Simulation

Background: Diagnosis and surgical treatment of hips with different types of pincer femoroacetabular impingement (FAI), such as protrusio acetabuli and acetabular retroversion, remain controversial because actual 3-dimensional (3D) acetabular coverage and location of impingement cannot be studied via standard 2-dimensional imaging. It remains unclear whether pincer hips exhibit intra- or extra-articular FAI. Purpose: (1) To determine the 3D femoral head coverage in these subgroups of pincer FAI, (2) determine the impingement-free range of motion (ROM) through use of osseous models based on 3D-computed tomography (CT) scans, and (3) determine the osseous intra-and extra-articular 3D impingement zones by use of 3D impingement simulation. Study Design: Cross-sectional study; Level of evidence, 3. Methods: This is a retrospective, comparative, controlled study involving 70 hips in 50 patients. There were 24 patients (44 hips) with symptomatic pincer-type or mixed-type FAI and 26 patients (26 hips) with normal hips. Surface models based on 3D-CT scans were reconstructed and compared for hips with acetabular retroversion (30 hips), hips with protrusio acetabuli (14 hips), and normal asymptomatic hips (26 hips). Impingement-free ROM and location of impingement were determined for all hips through use of validated 3D collision detection software based on CT-based 3D models. No abnormal morphologic features of the anterior iliac inferior spine were detected. Results: (1) Mean total femoral head coverage was significantly (P < .001) increased in hips with protrusio acetabuli (92% ± 7%) and acetabular retroversion (71% ± 5%) compared with normal hips (66% ± 6%). (2) Mean flexion was significantly (P < .001) decreased in hips with protrusio acetabuli (104°± 9°) and acetabular retroversion (116°± 6°) compared with normal hips (125°± 13°). Mean internal rotation in 90° of flexion was significantly (P < .001) decreased in hips with protrusio acetabuli (16°± 12°) compared with normal hips (35°± 13°). (3) The prevalence of extra-articular subspine impingement was significantly (P < .001) higher in hips with acetabular retroversion (87%) compared with hips with protrusio acetabuli (14%) and normal hips (0%) and was combined with intra-articular impingement. The location of anterior impingement differed significantly (P < .001) between hips with protrusio acetabuli and normal hips. Conclusion: Using CT-based 3D hip models, we found that hips with pincer-type and mixed-type FAI have significantly larger femoral head coverage and different osseous ROM and location of impingement compared with normal hips. Additionally, intra- and extra-articular subspine impingement was detected predominantly in hips with acetabular retroversion. Acetabular rim trimming during hip arthroscopy or open surgical hip dislocation should be performed with caution for these hips. Patient-specific analysis of location of impingement using 3D-CT could theoretically improve diagnosis and planning of surgical treatment.

Development of a deformable lung phantom with 3D-printed flexible airways.

Deformable lung phantoms have been proposed to investigate four-dimensional (4D) imaging and radiotherapy delivery techniques. However, most phantoms mimic only the lung and tumor without pulmonary airways. The purpose of this study was to develop a reproducible, deformable lung phantom with three-dimensional (3D)-printed airways. The phantom consists of: (a) 3D-printed flexible airways, (b) flexible polyurethane foam infused with iodinated contrast agents, and (c) a motion platform. The airways were simulated using publicly available breath-hold computed tomography (CT) image datasets of a human lung through airway segmentation, computer-aided design modeling, and 3D printing with a rubber-like material. The lung was simulated by pouring liquid expanding foam into a mold with the 3D-printed airways attached. Iodinated contrast agents were infused into the lung phantom to emulate the density of the human lung. The lung/airways phantom was integrated into our previously developed motion platform, which allows for compression and decompression of the phantom in the superior-inferior direction. We quantified the reproducibility of the density (lung), motion/deformation (lung and airways), and position (airways) using breath-hold CT scans (with the phantom compressed and decompressed) repeated every two weeks over a 2-month period as well as 4D CT scans (with the phantom continuously compressed and decompressed) repeated twice over four weeks. The density reproducibility was quantified with a difference image (created by subtracting the rigidly registered baseline and the repeated images) in each of the compressed and decompressed states. Reproducibility of the motion/deformation was evaluated by comparing the baseline displacement vector fields (DVFs) derived from deformable image registration (DIR) between the compressed and decompressed phantom CT images with those of repeated scans and calculating the difference in the displacement vectors. Reproducibility of the airway position was quantified based on DIR between the baseline and repeated images. For the breath-hold CT scans, the mean difference in lung density between baseline and week 8 was -1.3 (standard deviation 33.5) Hounsfield unit (HU) in the compressed state and 0.4 (36.8)HU in the decompressed state, while large local differences were observed around the high-contrast structures (caused by small misalignments). By visual inspection, the DVFs (between the compressed and decompressed states) at baseline and last time point (week 8 for the breath-hold CT scans) demonstrated a similar pattern. The mean lengths of displacement vector differences between baseline and week 8 were 0.5 (0.4)mm for the lung and 0.3 (0.2)mm for the airways. The mean airway displacements between baseline and week 8 were 0.6 (0.5)mm in the compressed state and 0.6 (0.4)mm in the decompressed state. We also observed similar results for the 4D CT scans (week 0 vs week 4) as well as for the breath-hold CT scans at other time points (week 0 vs weeks 2, 4, and 6). We have developed a deformable lung phantom with 3D-printed airways based on a human lung CT image. Our findings indicate reproducible density, motion/deformation, and position. This phantom is based on widely available materials and technology, which represents advantages over other deformable phantoms.

Triplanar convolution with shared 2D kernels for 3D classification and shape retrieval

Increasing the depth of Convolutional Neural Networks (CNNs) has been recognized to provide better generalization performance. However, in the case of 3D CNNs, stacking layers increases the number of learnable parameters linearly, making it more prone to learn redundant features. In this paper, we propose a novel 3D CNN structure that learns shared 2D triplanar features viewed from the three orthogonal planes, which we term S3PNet. Due to the reduced dimension of the convolutions, the proposed S3PNet is able to learn 3D representations with substantially fewer learnable parameters. Experimental evaluations show that the combination of 2D representations on the different orthogonal views learned through the S3PNet is sufficient and effective for 3D representation, with the results outperforming current methods based on fully 3D CNNs. We support this with extensive evaluations on widely used 3D data sources in computer vision: CAD models, LiDAR point clouds, RGB-D images, and 3D Computed Tomography scans. Experiments further demonstrate that S3PNet has better generalization capability for smaller training sets, and learns more of kernels with less redundancy compared to kernels learned from 3D CNNs.

Displaced Root of 3rd Maxillary Molar Tooth into Infratemporal Fossa- Role of 3D CT Scan

The displaced molar tooth is an unexpected and uncommon intraoperative complication of tooth extraction. Its prompt and early identification and management is crucial, as this may reduce the patient morbidity. Orthopantomogram (OPG) has limitations because of extensive anatomical superimposition of various structures. A 36-year-old female patient was referred for Computed Tomography (CT) of maxillofacial region with 3D CT scan for severe pain and swelling in right cheek region with inability to open mouth for 4 days following the dental intervention in outside dental clinic. CT scan of maxillofacial region showed bony defect in the right 3rd maxillary alveolus with multiple small bony fragments. Small fragment of molar tooth was displaced into the right infratemporal fossa and was impinging on right lateral pterygoid muscle with surrounding ill-defined soft tissue infiltrates in right retroantral fat. CT Face with 3D reconstruction helps in accurate localisation and gives appropriate anatomical detail in case of displaced molar tooth into infratemporal fossa. Thus, a detailed radiological investigation and documenting the relations of the displaced tooth or fragment with adjacent structures provides crucial information for proper surgical planning and avoiding possible complications.

Convolutional Neural Networks With Intermediate Loss for 3D Super-Resolution of CT and MRI Scans

Computed Tomography (CT) scanners that are commonly-used in hospitals and medical centers nowadays produce low-resolution images, e.g. one voxel in the image corresponds to at most one-cubic millimeter of tissue. In order to accurately segment tumors and make treatment plans, radiologists and oncologists need CT scans of higher resolution. The same problem appears in Magnetic Resonance Imaging (MRI). In this paper, we propose an approach for the single-image super-resolution of 3D CT or MRI scans. Our method is based on deep convolutional neural networks (CNNs) composed of 10 convolutional layers and an intermediate upscaling layer that is placed after the first 6 convolutional layers. Our first CNN, which increases the resolution on two axes (width and height), is followed by a second CNN, which increases the resolution on the third axis (depth). Different from other methods, we compute the loss with respect to the ground-truth high-resolution image right after the upscaling layer, in addition to computing the loss after the last convolutional layer. The intermediate loss forces our network to produce a better output, closer to the ground-truth. A widely-used approach to obtain sharp results is to add Gaussian blur using a fixed standard deviation. In order to avoid overfitting to a fixed standard deviation, we apply Gaussian smoothing with various standard deviations, unlike other approaches. We evaluate the proposed method in the context of 2D and 3D super-resolution of CT and MRI scans from two databases, comparing it to related works from the literature and baselines based on various interpolation schemes, using 2× and 4× scaling factors. The empirical study shows that our approach attains superior results to all other methods. Moreover, our subjective image quality assessment by human observers reveals that both doctors and regular annotators chose our method in favor of Lanczos interpolation in 97.55% cases for an upscaling factor of 2× and in 96.69% cases for an upscaling factor of 4×. In order to allow others to reproduce our state-of-the-art results, we provide our code as open source at https://github.com/lilygeorgescu/3d-super-res-cnn.

Exploiting tumor position differences between deep inspiration and expiration in lung stereotactic body radiation therapy planning

Purpose: We demonstrate proof of principle that normal tissue doses can be greatly reduced in lung stereotactic body radiation therapy (SBRT) for mobile tumors, if the delivered dose is split between opposite respiratory states. Methods: Patients that underwent 5 fraction lung SBRT at our institution and had deep inspiration breath hold (DIBH) and free breathing 4D computed tomography scans were included. Volumetric modulated arc therapy plans were generated on both respiratory phases and a third composite plan was generated delivering half the dose using the DIBH plan and the other half using the expiratory phase plan for each fraction. Computed tomography scans for the composite plan were fused based on ribs adjacent to the tumor to evaluate the dose volume histogram of critical structures. Results: Four patients with 4 total tumors had requisite planning scans available. Tumor size was between 0.7 to 2.9 cm and tumor movement 1.4 to 2.9 cm. Median reduction in the chest wall (CW) V30Gy for the composite plan was 74.6% (range 33.7 to 100%), 76.9% (range 32.9 to 100%), and 89.3% (range 69.5 to 100%) compared to the DIBH, expiration phase, and free breathing plans, respectively. Median reduction in CW maximum dose for the composite plan was 23.3% (range 0.27% to 46.4%), 23.5% (range 3.2 to 48.2%), and 23.4% (range 0.27% to 48.4%) compared to the DIBH, expiration phase, and free breathing plans, respectively. Greater reduction in CW maximum dose was observed when patients had no overlap in planning target volumes between DIBH and expiration phases (median reduction 43.9% for no overlap vs 2.7% with overlap). Between all plans, lung V20Gy absolute differences were within 1.3%. For 2 of 4 patients, the composite plan met constraints for 3 fraction SBRT, while standard plans did not. Conclusions: We conclude that composite DIBH-expiration SBRT planning has the potential to improve organ at risk sparing.

Intracranial Volume Post Cranial Expansion Surgery Using Three-Dimensional Computed Tomography Scan Imaging in Children With Craniosynostosis.

Craniosynostosis is a congenital defect that causes ≥1 suture to fuse prematurely. Cranial expansion surgery which consists of cranial vault reshaping with or without fronto-orbital advancement (FOA) is done to correct the skull to a more normal shape of the head as well as to increase the intracranial volume (ICV). Therefore, it is important to evaluate the changes of ICV after the surgery and the effect of surgery both clinically and radiologically. The aim of this study is to evaluate the ICV in primary craniosynostosis patients after the cranial vault reshaping with or without FOA and to compare between syndromic and nonsyndromic synostosis group, to determine factors that associated with significant changes in the ICV postoperative, and to evaluate the resolution of copper beaten sign and improvement in neurodevelopmental delay after the surgery. This is a prospective observational study of all primary craniosynostosis patients who underwent operation cranial vault reshaping with or without FOA in Hospital Kuala Lumpur from January 2017 until Jun 2018. The ICV preoperative and postoperative was measured using the 3D computed tomography (CT) imaging and analyzed. The demographic data, clinical and radiological findings were identified and analyzed. A total of 14 cases (6 males and 8 females) with 28 3D CT scans were identified. The mean age of patients was 23 months. Seven patients were having syndromic synostosis (4 Crouzon syndromes and 3 Apert syndromes) and 7 nonsyndromic synostosis. The mean preoperative ICV was 880 mL (range, 641-1234 mL), whereas the mean postoperative ICV was 1081 mL (range, 811-1385 mL). The difference was 201 mL which was statistically significant (P < 0.001). In comparison, the mean volume increment for syndromic synostosis and nonsyndromic synostosis was 282 mL and 120 mL, respectively. The difference was statistically significant (P < 0.004). Three months post-operation, the copper beaten sign was still present in the CT scan which was statistically not significant in this study (P > 1.0). However, there was 100% (n = 13) improvement of this copper beaten sign. However, the neurodevelopmental delay showed no improvement which was statistically not significant (P > 1.0). Surgery in craniosynostosis patient increases the ICV besides it improves the shape of the head. From this study, the syndromic synostosis had better increment of ICV compared to nonsyndromic synostosis.

Variability in total shoulder arthroplasty planning software compared to a control CT-derived 3D printed scapula.

Two techniques exist from which all 3D preoperative planning software for total shoulder arthroplasty are based. One technique is based on measurements constructed on the mid-glenoid and scapular landmarks (Landmark). The second is an automated system using a best-fit sphere technique (Automated). The purpose was to compare glenoid measurements from the two techniques against a control computed tomography-derived 3D printed scapula. Computed tomography scans of osteoarthritic shoulders of 20 patients undergoing primary total shoulder arthroplasty were analyzed with both 3D planning software techniques. Measurements from a 3D printed scapula (Scapula) from the true 3D computed tomography scan served as controls. Glenoid version and inclination measurements from each group were blinded and reviewed. In 65% (Automated) and 45% (Landmark) of cases, either inclination or version varied by 5° or more versus 3D printed scapula. Significant variability in version differences compared to the scapula group existed (p = 0.007). Glenoid version from the Scapula = 13.0° ± 10.6°, Automated = 15.0° ± 13.9°, and Landmark = 12.2° ± 7.8°. Inclination from Scapula = 5.4° ± 7.9°, Automated = 6.1° ± 12.6°, and Landmark = 6.2° ± 9.1°. A high percentage of cases showed discrepancies in glenoid inclination and version values from both techniques. Surgeons should be aware that regardless of software technique, there is variability compared to measurements from a control 3D computed tomography printed scapula.

Integration of triaxial testing and pore-scale visualization of methane hydrate bearing sediments.

Understanding mechanical interactions between hydrate and hosting sediments is critical for evaluating formation stability and associated environmental impacts of hydrate-bearing sediments during gas production. While core-scale studies of hydrate-bearing sediments are readily available and some explanations of observed results rely on pore-scale behavior of hydrate, actual pore-scale observations supporting the larger-scale phenomena are rarely available for hydrate-bearing sediments, especially with methane as guest molecules. The primary reasons for the scarcity include the challenge of developing tools for small-scale testing apparatus and pore-scale visualization capability. We present a testing assembly that combines pore-scale visualization and triaxial test capability of methane hydrate-bearing sediments. This testing assembly allows temperature regulation and independent control of four pressures: influent and effluent pore pressure, confining pressure, and axial pressure. Axial and lateral effective stresses can be applied independently to a 9.5 mm diameter and 19 mm long specimen while the pore pressure and temperature are controlled to maintain the stability of methane hydrate. The testing assembly also includes an X-ray transparent beryllium core holder so that 3D computed tomography scanning can be conducted during the triaxial loading. This testing assembly permits pore-scale exploration of hydrate-sediment interaction in addition to the traditional stress-strain relationship. Exemplary outcomes are presented to demonstrate applications of the testing assembly on geomechanical property estimations of methane-hydrate bearing sediments.

The normal evolution of the cranium in three dimensions

Insight into the growth and development of the normal newborn cranial shape is essential to monitor cranial development, to detect and diagnose abnormal skull shapes, and for the long-term follow-up of craniosynostosis surgery. The aim of this study was to analyse the growth pattern of the cranial shape of infants during the first years of life using 3D stereophotogrammetry and 3D computed tomography (CT) with advanced 3D evaluation techniques. A large set of 3D photographs (n=199) and CT scans (n=183), taken between ages 0 and 54 months, was collected. Cranial shapes with artefacts and asymmetries were removed. Total volumes and intracranial volumes were obtained, as well as 3D and 2D measurements, including the cranial width, cranial length, cranial index, and suture lengths. Growth maps were created for all modalities to indicate 3D growth over time. For the final analysis, a total of 130 3D photographs, 94 hard tissue CT scans, and 76 soft tissue CT scans were used. 3D and 2D measures, volumes, growth maps, and growth animations were obtained. A non-uniform growth was revealed by the 3D growth maps. This study addresses the need for normative cranial evolution data to monitor healthy cranial development and for detection, follow-up, and treatment planning in craniosynostosis.

The use of 2D-computed tomography scan as a first-line imaging modality in primary hyperparathyroidism

The use of 2D-computed tomography scan as a first-line imaging modality in primary hyperparathyroidism

Suitability of 3D-Printed Root Models for the Development of Transcatheter Aortic Root Repair Technologies.

Transcatheter aortic root repair (TARR) is still not available because of the complex anatomy. In order to develop future TARR technologies, a human-derived bench test model is required before performing animal tests. For this purpose, we aimed to validate computed tomography (CT)-derived 3D-printed root models for TARR technologies. Four human CT-derived roots were printed using different resins: Visijet M3 Crystal, Photopolymer gel SUP705, Formlabs flexible resin, and Materialise HeartPrint Flex. A stress test was performed using a 26-mm balloon-expandable Sapien valve deployed in aortic position. The too rigid Visijet M3 Crystal was not tested. Among the others, all but one (HeartPrint Flex, Materialise, Leuven, Belgium) ruptured during the test showing low wall resistances. Further tests were then performed in two roots made of HeartPrint Flex resin. The anatomic validation was performed comparing human CT scan-derived 3D reconstructions and CT scan measurements: a mean difference of 0.57 ± 0.4 mm for aortic annulus diameter and for the distance between the aortic annulus and the coronary ostia was measured. Concerning the coronary arteries, they are of paramount importance for new TARR technologies, and therefore, we tested the coronary flows of the HeartPrint Flex root at different pressure levels. At 60 mm Hg, right and left mean adjusted coronary flows were 471 and 663 ml/min; at 80 mm Hg, right and left mean coronary flows were 551 and 777 ml/min; and at 100 mm Hg, right and left mean coronary flows were 625 and 858 ml/min. In our study, 3D-printed root models correlate well with human anatomy and guarantee physiologic coronary flows for TARR technologies.