Cone-beam Tomography Research Articles

Intraoperative Cone Beam Tomography and Navigation for Displaced Acetabular Fractures: A Comparative Study.

To evaluate the accuracy of reduction of the acetabular articular surface using an intraoperative computed tomography scanner (O-Arm) and screw navigation compared with a classical open technique. Prospective matched cohort study. Tertiary referral center. Adult patients with acute acetabular fractures were included in the study. All patients were treated by 2 senior surgeons using intraoperative imaging and screw navigation. The primary outcome measure was articular reduction. Secondary outcomes were radiation dosage, operative variables [operative time, time for image acquisition, intraoperative bleeding (cell saver), number of surgical plates, and number of screws], and postoperative variables (first postoperative day pain on the visual analog scale, postoperative transfusion, and hemoglobin change). P < 0.05 was considered statistically significant. Thirty-five patients were treated in the inclusion period (2016-2017) and were matched to 35 cases in our database (2013-2016). Mean age was 43 years, and the most common fracture type was a both-column fracture (OTA/AO type C). Postoperative image analysis showed that reduction was achieved in 87.1% of the cases in the O-Arm group versus 64.7% in the control group (P < 0.05). Mean gap of the articular fragments was 3.6 mm in the O-Arm group compared with 5.6 mm (P = 0.01) in the control group. There was no significant difference between the 2 groups in regards to all other studied variables except a decrease in intraoperative blood loss and transfusions and an increase in surgical time with the O-Arm group. Finally, the total radiation dose was decreased using the intraoperative O-Arm compared with a routine postoperative computed tomography scan (dose length product in O-Arm: 498 mGy.cm; dose length product in historical group: 715 mGy.cm). Using intraoperative imaging and screw navigation for displaced acetabular fractures allow screw navigation with increasing articular surface reduction accuracy. Operative and anesthesia times were not increased, whereas radiation exposure to the patient was significantly decreased. We recommend the use of intraoperative imaging for the treatment of displaced acetabular fractures. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Development of a markerless tumor-tracking algorithm using prior four-dimensional cone-beam computed tomography.

Respiratory motion management is a huge challenge in radiation therapy. Respiratory motion induces temporal anatomic changes that distort the tumor volume and its position. In this study, a markerless tumor-tracking algorithm was investigated by performing phase recognition during stereotactic body radiation therapy (SBRT) using four-dimensional cone-beam computer tomography (4D-CBCT) obtained at patient registration, and in-treatment cone-beam projection images. The data for 20 treatment sessions (five lung cancer patients) were selected for this study. Three of the patients were treated with conventional flattening filter (FF) beams, and the other two were treated with flattening filter-free (FFF) beams. Prior to treatment, 4D-CBCT was acquired to create the template projection images for 10 phases. In-treatment images were obtained at near real time during treatment. Template-based phase recognition was performed for 4D-CBCT re-projected templates using prior 4D-CBCT based phase recognition algorithm and was compared with the results generated by the Amsterdam Shroud (AS) technique. Visual verification technique was used for the verification of the phase recognition and AS technique at certain tumor-visible angles. Offline template matching analysis using the cross-correlation indicated that phase recognition performed using the prior 4D-CBCT and visual verification matched up to 97.5% in the case of FFF, and 95% in the case of FF, whereas the AS technique matched 83.5% with visual verification for FFF and 93% for FF. Markerless tumor tracking based on phase recognition using prior 4D-CBCT has been developed successfully. This is the first study that reports on the use of prior 4D-CBCT based on normalized cross-correlation technique for phase recognition.

Three-dimensional evaluation of open-bite patients treated with anterior elastics and curved archwires.

One nonsurgical treatment method for a patient with open bite is to use curved nickel-titanium arches and anterior elastics. The aim of this study was to investigate the effects of this technique with cone-beam computed tomography. Eighteen open-bite patients' treatment records were used for this retrospective study. The treatment methods were identical for all patients, beginning with the levelling and alignment of the teeth and the placement of maxillary accentuated and mandibular reverse curved archwires with anterior elastics. Cone-beam tomography images were taken and analyzed 3 dimensionally. The paired-samples t test statistical analysis was performed. A-point moved anteriorly (0.33mm) and the SN-MP angle increased slightly (1.17°). Maxillary and mandibular incisors were extruded by 2.16 and 1.49mm, respectively. Overbite increased (4.38mm). There were no significant changes in the vertical parameters of the premolars and molars. The open bite was eliminated by retraction and extrusion of the anterior teeth while maintaining the vertical positions of the molars.

Blood clot stability and bone formation following maxillary sinus membrane elevation and space maintenance by means of immediate implant placement in humans. A computed tomography study

ObjectiveThe present controlled clinical pilot study proposed to assess blood clot contraction and bone neo-formation following maxillary sinus lift (MSL) with immediate implant placement without using grafts using cone beam tomography exams. Materials and methodsTen implants were placed in ten patients with a residual bone crest height ≥4 and ≤ 7 mm, in maxillary premolars or 1st or 2nd molars regions, using MSL and immediate implant placement without grafts, by means of the lateral window approach. A resorbable membrane (Bio-Gide®, Geistlich, USA) was used to close the window. Computed tomography images were taken after 15 (T1) and 180 (T2) days to assess the rate of blood clot contraction and bone neo-formation. The images were analysed by OsirixMD software. The Shapiro Wilk test was used to verify the normality hypothesis and the data were submitted to Student's paired t-test. ResultsThe mean of bone clot height in mesial, apical and distal area referred to implant, presented 4.77 mm, 0.77 mm and 5.30 mm respectively. The mean measurements of new bone formation presented 2.95 mm, 0.44 mm and 3.45 mm. The height contraction (coagulum/new bone formation), between T1 and T2, presented 38%, 43% and 35% respectively, with a significant statistical value p < 0.05.The volume measurements at T1 presented a mean volume of 0.90 cm3 sd ± 0.60 cm3 and at T2 a mean volume of 0.75 cm3 sd ± 0.62 cm3, with a significant volume contraction between T1 and T2, p < 0.005. The mean blood clot contraction was 16.52% ± 8.60%. ConclusionThe present study demonstrates consistent bone formation around all assessed implants, although with significant contraction of the blood clot. The need for longitudinal studies to establish a long-term prognosis in different modalities of prosthetic rehabilitation of those implants is strongly suggested.

New technique for alveolar preservation – the anodized titanium foil concept

Background The socket preservation techniques are used to minimize bone loss and maintain gingival tissues volume after tooth extraction. However, the volume preservation rate of the alveolar process is not predictable, and most of the guided bone regeneration techniques change the mucogingival line by coronally positioning the flap to cover a membrane, what may impair implant aesthetics and function. Aim/Hypothesis The aim of this clinical prospective study was to evaluate a new alveolar preservation technique using an anodized titanium membrane (ATM), which remain exposed to the oral cavity, analyzing tomographical bone measurements pre-surgically and 6 months after surgery. Material and Methods Eighteen healthy patients having one hopeless tooth were selected to receive the new socket preservation technique. The teeth were carefully extracted, then a small flap was raised to allow the ATM insertion. The alveolus was filled with anorganic bovine bone graft and the ATM was trimmed and adapted over the crestal bone and below the gingival margin. Nylon sutures were used to hold the ATM in position. Proper post-operatory medications were prescribed (Amoxicylin 500 mg, Ibuprofen 200 mg and PerioGard rinse). Fifteen days after surgery the ATMs were removed with pliers. The measurements of the alveolus thickness were recorded in the baseline and 6 months after the surgeries, using cone beam tomographies, evaluating the distance between buccal and palatal bone plates, and were performed in the center of the alveolus, 1 mm above the palatal crestal bone. The data was statistically analyzed by Student´s t-test (P < 0.05 was considered). Results The results are presented in percentage, to minimize the influence of the different alveolus sizes. After 6 months, the mean volume maintenance was 97.66% (P = 0.07) for all the 18 patients. In cases with vestibular bone plate loss (7 patients), the average of volume maintenance was 112.89%, with some volume gain (P = 0.07). When there was no vestibular bone plate loss (11 cases) the result was 87.97% (P = 0.002). Evaluation the type of teeth, for molar teeth (7 cases), mean volume maintenance was 89.55% (P = 0.014), and for no molar teeth (11 cases), the average of volume maintenance was 102.82% (P = 0.46). Conclusions and Clinical Implications The use of ATM in this prospective case series presented superior tomographic results for tissue volume maintenance after 6 months, when compared to the scientific literature addressing GBR procedures using collagen membranes and connective tissue grafts. Future randomized controlled clinical studies are suggested to investigate the regenerative potential of this new alveolar preservation technique.

Geometrical parameters of the mandible in 3D CBCT imaging

The aim of the study is to report on a method for the measurement and analysis of the accuracy in mapping the shape of the mandible spatially modeled based on cone beam imaging. To achieve this goal, the geometrical determinants of the mandible shape were identified; in addition, the accuracy of their cone beam in computer tomography (CBCT) images was verified. The latter – verification of images – was based on reference measures made by a coordinate measuring machine (CMM). The parameters that were analyzed were: Bonville's triangle, the occlusal plane, and the mandible symmetry in relation to the sagittal plane. Descriptive statistics and distribution of individual variables were determined. The results were analyzed statistically using the U-Mann Whitney test. The geometrical parameters of the mandible determined on the basis of CBCT and CMM imaging do not differ significantly.

Evaluation of Alveolar Ridge Preservation Using a composite of Bioactive Glass and Platelet Rich Fibrin Alone or Combined with Melatonin in Chronic Periodontitis Patient

Purpose: The aim of this randomized controlled clinical trial was the evaluation of alveolar ridge preservation using a composite of bioactive glass and platelet rich fibrin either alone or combined with melatonin in chronic periodontitis patients. This aim was fulfilled through: Clinical assessment and radiographic assessment. Subjects and Methods: A total of thirty extraction sockets in 29 patients were randomly divided into three groups; control group treated by atraumatic extraction alone, test1 group (application of bioactive glass mixed with PRF) and test 2 group (application of bioactive glass mixed with PRF and melatonin gel). The clinical parameters recorded at baseline, 3 months and 6 months after treatment. Cone beam tomography radiographs used to measure width of socket at base line and 6months post operatively. Results: By clinical assessment both group II and group III showed significant increase in length and width of alveolar ridge with significant difference between the two groups in the whole study period. Radiographically; both group II and group III showed a significant increase in all parameters by time, while control group, there was a significant decrease at the end of the study period. Conclusion: Within the limits of this study: The composite use of bioglass, Prf & melatonin in group III reflected the best clinical, and radiographic results.

Evaluation of the Portal Imaging System Performance for an Elekta Precise Linac in Radiotherapy

Introduction: Electronic portal imaging devices (EPIDs) provide two- and three-dimensional planar and volumetric cone beam images to improve the accuracy of radiation treatment delivery. Periodic quality assurance (QA) of EPIDs is essential for dosimetric verification in radiotherapy. In this study, a QA program was implemented to evaluate the function of the EPID to be confident in applying corrections for the uncertainty of patient set-up. Material and Methods: Firstly, the safety features were verified, and the uniformity of EPID response was evaluated using flat panel detector. Additionally, the contrast and spatial resolutions of the EPID were assessed using detail counting of the Los Vegas phantom images by visualization method and measuring the modulation transfer function using edge technique, respectively. Moreover, a combination of smoothing methods was used for optimal use of edge detection algorithm for the noisy portal images. Finally, the location of the central ray on the EPID surface at different gantry angles was determined to evaluate the mechanical stability of the supporting arm. Results: The safety interlocks were found to be functional.The EPID response variation was less than 3% according to the results obtained from the detector. The contrast resolution met the recommended tolerance; however, the visualization method was widely observer-dependent. The value of f50 for spatial resolution was 0.401±0.005 lp/mm for the photon energy of 6 MV. The supporting arm deviation was within ±1 mm. Conclusion: The periodic QA of image guidance system gave confidence to apply the corrections for set-up in clinic.

Feasibility of real‐time lung tumor motion monitoring using intrafractional ultrasound and kV cone beam projection images

The ability to monitor intrafractional tumor motion is essential for radiation therapy of thoracic and abdominal tumors. This study aims to develop a method to track lung tumor motion using intrafractional continuous ultrasound (US) and periodic cone-beam projection images (CBPI). Time-sequenced b-mode US and CBPI data were extracted from the data acquired with the Clarity® and XVI platforms on an Elekta linac, respectively. The data were synchronized through a video capture card (VCE-PRO, IMPERX Inc.) which was triggered by the XVI system. In this way, a system was configured to allow real-time acquisition of the diaphragm position synchronized with periodic acquisition of the lung tumor position. Feasibility of the system was demonstrated by acquiring synchronized data on an in-house motion platform with embedded spheres of different materials and US images of the diaphragm on 5 volunteers of various body sizes. Finally, ultrasound b-mode images and CBPI were also acquired simultaneously from 3 lung cancer patients. Diaphragm motion monitoring under free breathing (FB) was successful with intracostal US imaging. We observed that diaphragm visualization decreased with the increase in the body size of the volunteer. The US system was able to track the motion as small as 2mm in the phantom. The intrafractional CBPI acquired during VMAT delivery was successfully synchronized with US acquisition in a phantom study. Collected patient data showed a significant correlation between diaphragm motion, an internal surrogate monitored by US, and the tumor motion in superior-inferior (SI) direction monitored by XVI (P˂0.0001). The feasibility of real-time lung tumor motion tracking in SI direction with continuous ultrasound and periodic CBPI was demonstrated. The real-time estimation of the target position from the two streams for lung cancer patients would enable respiration gating or tracking during SBRT.

Tomographic approach for the quantitative scene reconstruction from light field images.

Current computational methods for light field photography model the ray-tracing geometry inside the plenoptic camera. This representation of the problem, and some common approximations, can lead to errors in the estimation of object sizes and positions. We propose a representation that leads to the correct reconstruction of object sizes and distances to the camera, by showing that light field images can be interpreted as limited angle cone-beam tomography acquisitions. We then quantitatively analyze its impact on image refocusing, depth estimation and volumetric reconstructions, comparing it against other possible representations. Finally, we validate these results with numerical and real-world examples.

OA151] Error sensitivity of forward- and back-projection EPID dosimetry for VMAT treatment of the prostate

Introduction Volumetric modulated arc therapy (VMAT) treatments may be verified dosimetrically using an electronic portal imaging device (EPID), either using the forward-projection method to calculate integrated predicted images, which are compared with acquired images, or using the back-projection method to reconstruct delivered dose, for comparison with the planned dose. This study compares the error sensitivity of both methods for prostate treatments. Materials and Methods VMAT treatment plans for prostate and seminal vesicles were created using AutoBeam in-house software, with final dose calculation carried out in Pinnacle3. Patients were treated using the 6 MV beam of a Versa HD accelerator. Portal images were acquired for 46 fractions in 13 patients, and EPID dosimetry was carried out using AutoBeam (forward-projection) and iViewDose (back-projection). Differences between measurements (M) and predictions (P) were evaluated on the central axis of the beam (forward-projection) and at the isocentre (back-projection). The plans were also retrospectively delivered to a Solid Water phantom and errors were deliberately introduced. Errors consisted of a 2–10% increase in monitor units, a 2–10 mm increase in aperture size, a 2–10 mm shift in aperture and introduction of a 10–50 mm air gap into the phantom. Results For the patient images, M-P = 3.1% ± 2.1% (1 SD) for forward-projection and 2.2% ± 2.2% for back-projection, with good correlation between forward-projection and back-projection. For the phantom images, M-P = 0.7% ± 2.0% for forward-projection and 3.0% ± 1.0% for back-projection. Monitor unit and aperture size errors are detected equally by both methods, aperture shift errors are mainly detected in forward-projection due to removal of shifts by the back-projection image processing software, while air gaps have a slightly larger impact on back-projection than forward-projection. Conclusions Each method of EPID dosimetry has its own distinct sensitivity to errors, but overall, both methods can be used reliably for verification of delivered dose. The back-projection method, in clinical use at this centre, enables convenient visualisation of delivered dose to the patient. Other methods, such as cone-beam imaging, are required for verification of patient position, while further work is needed to investigate the potential of time-resolved EPID dosimetry.

Calibration of Robotic Manipulator Systems for Cone-Beam Tomography Imaging

Image reconstruction of tomographic data relies on the precise knowledge of the geometric properties of the scan system. Common tomography systems, such as rotational tomography, C-arm systems, helical scanners, or tomosynthesis scanners, generally use motions described by a few rotational or linear motion axes. We are interested in applications in nondestructive testing, where objects might have large aspect ratios and complex shapes. For these problems, more complex scan trajectories are required, which can be achieved with robotic manipulator systems that have several linear or rotational degrees of freedom. For the geometric calibration of our system, instead of using an approach that scans a calibrated phantom with markers at a known relative position, we propose an approach that uses one (or several) markers with unknown relative positions. The fiducial marker is then moved by a known amount along one degree of freedom, thus tracing out a “virtual” phantom. Using the assumed spacial locations of the markers together with the locations of the markers on the imaging plane, we use a nonlinear optimization method to estimate the orientation of the linear and rotational manipulator axes, the detector and source location, and the detector orientation.

Craniomaxillofacial patient-specific CAD/CAM implants based on cone-beam tomography data – A feasibility study

Customized implants have simplified surgical procedures and have improved patient outcome in craniomaxillofacial surgery. Traditionally, patient-specific data is gathered by conventional computed tomography (CT). However, cone-beam CT (CBCT) can generate a 3D reconstruction of the area of interest with a lower dose of radiation at reduced cost. In this study, we investigated the feasibility of using CBCT data to design and generate customized implants for patients requiring craniomaxillofacial reconstruction. We used CBCT to generate 62 implants for 51 consecutive patients admitted to our department between January 2015 and December 2017. The indications for reconstruction and types of reconstruction were very variable. In all cases, the implants were well fitted and no implant-related complications were detected. Pre-surgical planning was faster and more efficient as we did not have to consult a radiologist. Although CBCT data is more difficult to process than conventional CT data for the implant provider, the clinical advantages are pronounced and we now use CBCT as standard in our department. In conclusion, we have shown that using CBCT to design and manufacture customized implants for reconstruction of the craniomaxillofacial area is feasible and recommend this approach to other departments.

Simulation of a three-dimensional craniofacial structure under the application of orthodontic loads

The aim of this study was to develop a three-dimensional model of a patient’s craniofacial structure to be analysed using the finite element method in order to estimate the forces required to carry out a dental positioning’s correction. The three-dimensional model was composed by several anatomical structures, namely the teeth, the periodontal ligaments, and the trabecular and cortical bones, which were modelled with the aid of computed tomography cone beam images. The tomographic images were analysed and reconstructed using the 3D Slicer software, while the assembly of the anatomical structures modelled, as well as the contact surfaces between contiguous parts, was defined in computer-aided design software. Bone remodelling and the occurrence of tissue’s injuries were considered during the numerical simulations carried out. By imposing displacements to each tooth, it was possible to calculate the orthodontic loads needed to carry out dental correction (reaction forces), as well as the distributions of stresses and deformations inherent to the clinical treatment, allowing to obtain a craniofacial structure capable of simulating the dental movements of upper and lower arches with anatomical realism. In addition, this methodology constitutes a personalised dental medicine that could lead to the development of highly customised orthodontic appliances where different mechanical loads could be applied individually to each tooth to achieve the foreseen dental correction.

Doesthe association of blood-derived growth factors to nanostructured carbonated hydroxyapatite contributes to the maxillary sinus floor elevation? A randomized clinical trial.

The combination of calcium phosphate with blood-derived growth factors (BDGF) has been widely used in bone regeneration procedures although its benefits are still unclear. The purpose of this study was to evaluate whether or not BDGF improves the efficacy of a modified carbonated calcium phosphate biomaterial in sinus floor augmentation. Ten patients underwent 20 sinus floor augmentation procedures using nanostructured carbonated hydroxyapatite (cHA) microspheres alone or associated with BDGF in a randomized controlled clinical trial. The in vitro release of growth factors was assessed by an elution assay. Bone grafts were randomly implanted in the right and left maxillary sinuses of each participant, associated either with a 0.9% saline solution or BDGF. Bone gain was evaluated through cone beam tomography after 180days. Nine women and one man composed the sample. The blood-derived concentrates were able to release high levels of growth factors and cytokines. A significant clinical advantage was observed in the use of the BDGF after fibrin polymerization around the biomaterial microspheres, optimizing the surgical procedures, thereby reducing the time and displacement, and improving the adaptation of the biomaterial in the maxillary sinus. No synergistic effect was observed in bone formation when cHA was associated with BDGF (p > 0.05). Equivalent new bone formation was observed for cHA in the presence or absence of the BDGF concentrate in bilateral sinus floor elevation after 6months. Blood-derived growth factors did not improve bone repair when associated with calcium phosphate in sinus lift procedures.

Adaptive radiotherapy for head and neck cancers: Fact or fallacy to improve therapeutic ratio?

Modern standards of precision radiotherapy, primarily driven by the technological advances of intensity modulation and image guidance, have led to increased versatility in radiotherapy planning and delivery. The ability to shape doses around critical normal organs, while simultaneously “painting” boost doses to the tumor have translated to substantial therapeutic gains in head and neck cancer patients. Recently, dose adaptation (or adaptive radiotherapy) has been proposed as a novel concept to enhance the therapeutic ratio of head and neck radiotherapy, facilitated in part by the onset of molecular and functional imaging. These contemporary imaging techniques have enabled visualisation of the spatial molecular architecture of the tumor. Daily cone-beam imaging, besides improving treatment accuracy, offers another unique angle to explore radiomics – a novel high throughput feature extraction and selection workflow, for adapting radiotherapy based on real-time tumor changes. Here, we review the existing evidence of molecular and functional imaging in head and neck cancers, as well as the current application of adaptive radiotherapy in the treatment of this tumor type. We propose that adaptive radiotherapy can be further exploited through a systematic application of molecular and functional imaging, including radiomics, at the different phases of planning and treatment.

Tomografía cone beam como herramienta diagnóstica en alteraciones de la articulación temporomandibular

La tomografía computarizada Cone Beam es una herramienta que facilita el diagnóstico de diferentes alteraciones de la artculación temporomandibular mediante el escaneado y la obtencion del volumen especifico de la cabeza del paciente, generando resultados en 3D, con baja dosis de radiación comparada con los tomógrafos médicos, la cual permite cuantificar y cualificar los tejidos óseos sin distorsiones, con informacion detallada y precisa, para obtener diagnósticos confiables. El propósito de éste artículo es sitematizar la literatura reportada sobre el uso de la tomografía cone beam, como herramienta diagnóstica en pacientes con alteraciones temporomandibulares, contribuyendo como texto didáctico de referencia, proporcionando y resumiendo la información publicada sobre ésta nueva técnica. Se describen las características imagenológicas de cone beam de las diferentes patologías asociadas a la articulación temporomandibular, así como algunos criterios para la evaluación pre y pos tratamiento de la misma.

ESTUDIO MORFOLÓGICO DE LOS CANALES RADICULARES DEL PRIMER PREMOLAR SUPERIOR, UTILIZANDO RADIOGRAFÍA PERIAPICAL Y TOMOGRAFÍA DE HAZ CÓNICO, EN EL CENTRO RADIOLÓGICO DENTAL-MAXILOFACIAL, CUENCA 2015

&#x0D; &#x0D; &#x0D; La CBCT (cone beam computed tomography), es un gran avance en el diagnóstico por imágenes. Se basa en la reconstrucción de imágenes en 3D para un diagnóstico más acertado. El presente estudio tiene por objeto esUtundiivaer rlasidmaodrfoClaotgóíalicdae dloes canales radiculares del primer premolar superior, utilizando radiografía periapical y tomografía de haz cónico.&#x0D; El tipo de estudio es in vitro, descriptivo y transversal, la muestra es por conveniencia, puesto que no se dispuso de una población específica para guia, por lo que se seleccionaron 50 dientes (Primeros Premolares Superiores), extraídos por motivo ortodóntico. Las imágenes obtenidas mediante radiografías intra orales revelan una información en dos dimensiones, lo que nos limita en el diagnóstico. En determinadas situaciones la visualización en tres dimensiones de un problema endodóntico es necesaria. El resultado del presente estudio denota que radiográficamente se obtienen datos acertados sobre la morfología de las piezas que presentaban un solo conducto o dos raíces separadas, siendo más efectivo el uso de la tomografía para la descripción de piezas con un sistema de conductos más complejo.&#x0D; &#x0D; &#x0D;

EVALUATION OF FRACTURE RESISTANCE AND FIT ACCURACY OF THREE TYPES OF CAD/CAM FABRICATED CROWNS USING CONE BEAM COMPUTERIZED TOMOGRAPHY

Aim: The aim of this study was to evaluate the internal and marginal fit accuracy using cone beam computerized tomography as an innovative nondestructive method and to assess the fracture resistance of the recently introduced zirconia reinforced lithium silicate glass ceramic in comparison to lithium disilicate and monolithic zirconia. Materials and Methods: Three types of CAD/ CAM ceramic blocks were used; zirconia reinforced lithium silicate glass ceramics (Vita Suprinity), lithium disilicate glass ceramic (IPS e.max CAD) and partially sintered translucent zirconia (In-Coris TZI). A ceramic master die was fabricated and scanned using the Cerec Omnicam to produce a total number of 30 crowns, which were divided into 3 groups (n = 10) according to the ceramic material used . Group I: Vita Suprinity. Group II: IPS e.max CAD and Group III: In- Coris TZI. A highly computerized cone beam tomography (CBCT) was used to evaluate the fit accuracy of the crowns on the master die. For fracture resistance test, epoxy resin dies were optically scanned using Omnicam scanner and 30 crowns were fabricated using the CAD/ CAM ceramic materials (n = 10) for each tested material. The crowns were cemented using self-adhesive resin cement. A compressive load was applied at a cross head speed of 1mm/min and the fracture load in Newtons was recorded for each specimen. Fractured crowns were examined to determine the mode of fracture. Results: Marginal and internal fit evaluation showed that group I (Vita Suprinity) recorded the least mean in respect to all measuring points (103.6±10.4μm), while group III (In Coris TZI) showed the highest mean in respect to all points (146.7±9.23μm). For fracture resistance, In Coris TZI zirconia showed the highest fracture load (4548.9±200.9 N), while the lowest mean value was recorded in Vita Suprinity (3484.8±22.17 N). There was no significant difference between Vita Suprinity and IPS e.max CAD. Conclusion: Vita Suprinity crowns showed the best marginal and internal fit when compared to the other two materials. In- Coris TZI exhibited the highest fracture strength of all three groups. All values were within a clinically acceptable range for the three ceramic materials tested

Dual-phase Cone-beam CT-based Navigation Imaging Significantly Enhances Tumor Detectability and Aids Superselective Transarterial Chemoembolization of Liver Cancer

The objective of this study was to investigate the impact of a dual-phase cone-beam computed tomography (DP-CBCT)-based navigation imaging during transarterial chemoembolization (TACE) of hepatocellular carcinoma (HCC) in a perspective randomized study. Forty-two patients with HCC (39 men, 57 ± 9 years, 13 first-time TACE) underwent TACE using three-dimensional image guidance with automatic detection of tumor-feeding vessels computed from DP-CBCT (early and delayed arterial phases). Forty-nine other patients with HCC (44 men, 55 ± 12 years, 14 first-time TACE) were treated conventionally using digital subtraction angiography (DSA). Tumor detectability in DP-CBCT was compared to DSA and preoperative CT or magnetic resonance (MR) imaging. Tumor-feeding vessel visibility was rated (good, fair, and poor) intraoperatively by the operators. The superselective embolization success rate, the number of DSA acquisitions, fluoroscopy time, and patient radiation dose were collected and compared using paired t test and the Mann-Whitney U test. Tumor detection of DP-CBCT was superior to DSA (100% vs 83%, P = .001) and comparable to CT-MR (96%, P = .456). Tumor and feeder visibilities were significantly enhanced by DP-CBCT (P < .001). Compared to using DSA, more superselective embolization was achieved (60% vs 49%) with less DSA acquisitions (n = 2.6 ± 0.8 vs n = 3.4 ± 0.7, P < .001) and shorter fluoroscopy time (4.1 ± 2.6 vs 7.1 ± 4.2 minutes, P < .001) with a slight increase in patient radiation exposure, that is, air kerma (median: 0.33, first to third quartiles: 0.24-0.48 vs 0.30, 0.24-0.44 Gy; P = .519) and dose-area product (134, 92-181 vs 97, 75-140 Gy⋅cm2, P = .048). DP-CBCT and navigation imaging improve tumor detectability and superselective embolization in TACE.