Digital Subtraction Technique Research Articles

Influence of scan technology on the accuracy and speed of intraoral scanning systems for the edentulous maxilla: An in vitro study.

To compare the accuracy of three intraoral scanners in terms of trueness and precision relative to the scanner acquisition technology and scan capture mode. Scan speed of each scanner was also evaluated. An edentulous maxillary arch was digitized (reference model) and 3D-printed using an SLA-based 3D-printer (XFAB; DWS, Italy) (n=10). Each model was scanned using three intraoral scanners, each with different scan technologies: confocal (Trios 3; 3Shape, Copenhagen, Denmark), parallel confocal (iTero; Align Technology), and triangulation (Medit i700). Scan time and scanning accuracy (trueness and precision) were calculated using digital subtraction technique (Geomagic Control X v2020, 3DSystems, USA). One-way analysis of variance (ANOVA) test was used to detect differences in trueness, precision, and scanning time between the tested groups (p<0.05). ANOVA results showed statistically significant differences in trueness, precision, and scan time among the tested groups. Confocal scanning technique (Trios 3) showed the highest trueness and precision (root mean square estimate [RMSE] 0.094 and 0.096, respectively) followed by iTero displaying parallel confocal technique (RMSE 0.113 and 0.133, respectively); the difference was not significant (p=0.849, p=0.488). Further, Trios showed the longest scanning time (100s) compared to iTero and Medit i700 (p=0.011 and 0.002, respectively). Medit i700 presenting triangulation scan technology revealed lowest trueness and precision (RMSE 0.268) (p=0.000, p=0.001) and fastest scan time (59s) close to iTero (66s) (p=0.802). Scanner technology had an influence on the accuracy and scan speed of the acquired intraoral scans. The Trios 3 scanner featuring the confocal acquisition technology displayed the highest trueness, precision, and longest scan time. Medit i700 IOS with triangulation acquisition concept featured the lowest trueness, precision, and fastest scan speed. There is no ideal scanner with the best combination of accuracy and scan speed.

Does the palatal vault form have an influence on the scan time and accuracy of intraoral scans of completely edentulous arches? An in-vitro study.

The purpose of this study was to evaluate the influence of different palatal vault configurations on the accuracy and scan speed of intraoral scans (IO) of completely edentulous arches. Three different virtual models of a completely edentulous maxillary arch with different palatal vault heights-Cl I moderate (U-shaped), Cl II deep (steep) and Cl III shallow (flat)-were digitally designed using CAD software (Meshmixer; Autodesk, USA) and 3D-printed using SLA-based 3D-printer (XFAB; DWS, Italy) (n = 30; 10 specimens per group). Each model was scanned using intraoral scanner (Trios 3; 3Shape™, Denmark). Scanning time was recorded for all samples. Scanning accuracy (trueness and precision) were evaluated using digital subtraction technique using Geomagic Control X v2020 (Geomagic; 3DSystems, USA). One-way analysis of variance (ANOVA) test was used to detect differences in scanning time, trueness and precision among the test groups. Statistical significance was set at α = .05. The scan process could not be completed for Class II group and manufacturer's recommended technique had to be modified. ANOVA revealed no statistically significant difference in trueness and precision values among the test groups (P =.959 and P =.658, respectively). Deep palatal vault (Cl II) showed significantly longer scan time compared to Cl I and III. The selection of scan protocol in complex cases such as deep palatal vault is of utmost importance. The modified, adopted longer path scan protocol of deep vault cases resulted in increased scan time when compared to the other two groups.

Comparative Evaluation of Efficacy between Recombinant Human Bone Morphogenetic Protein-2 Impregnated with Absorbable Sponge and Platelet-Rich Fibrin in the Treatment of Grade II Furcation Defects: A Randomized Controlled Trial.

Aim and Objectives:The objective of the study was to clinically and radiographically compare and evaluate the regenerative potential of recombinant human bone morphogenetic protein-2 (RhBMP-2) impregnated with absorbable collagen sponge and platelet-rich fibrin (PRF) in the treatment of Grade II furcation defects.Patients and Methods:Thirty-two subjects were randomly assigned to each of the following groups: bone morphogenetic protein (BMP) group and PRF group, with one defect/subject. Sixteen Grade II furcation defects were treated with RhBMP-2 impregnated with absorbable collagen sponge in the BMP group and the remaining 16 defects were treated with PRF in the PRF group. Clinical and radiographic parameters which were evaluated at baseline, postoperative 1 week, 3 months, and 6 months were probing pocket depth, clinical attachment level, scoring of plaque index, and gingival index, and the bone fill was evaluated using Digital Subtraction technique and morphometric area analysis with ImageJ® software.Results:RhBMP-2 in absorbable collagen sponge was effective in increasing the bone fill in Grade II furcation defects when compared to PRF alone (P = 0.05). In relation to clinical parameters, both the groups showed no statistical significance between them.Conclusion: The unique regenerative potential of RhBMP-2 impregnated with absorbable collagen sponge makes it a potential agent to be used as a graft material for the treatment of Grade II furcation defects.

Brain Tumour Temporal Monitoring of Interval Change Using Digital Image Subtraction Technique.

A process that involves the registration of two brain Magnetic Resonance Imaging (MRI) acquisitions is proposed for the subtraction between previous and current images at two different follow-up (FU) time points. Brain tumours can be non-cancerous (benign) or cancerous (malignant). Treatment choices for these conditions rely on the type of brain tumour as well as its size and location. Brain cancer is a fast-spreading tumour that must be treated in time. MRI is commonly used in the detection of early signs of abnormality in the brain area because it provides clear details. Abnormalities include the presence of cysts, haematomas or tumour cells. A sequence of images can be used to detect the progression of such abnormalities. A previous study on conventional (CONV) visual reading reported low accuracy and speed in the early detection of abnormalities, specifically in brain images. It can affect the proper diagnosis and treatment of the patient. A digital subtraction technique that involves two images acquired at two interval time points and their subtraction for the detection of the progression of abnormalities in the brain image was proposed in this study. MRI datasets of five patients, including a series of brain images, were retrieved retrospectively in this study. All methods were carried out using the MATLAB programming platform. ROI volume and diameter for both regions were recorded to analyse progression details, location, shape variations and size alteration of tumours. This study promotes the use of digital subtraction techniques on brain MRIs to track any abnormality and achieve early diagnosis and accuracy whilst reducing reading time. Thus, improving the diagnostic information for physicians can enhance the treatment plan for patients.

Selective Segmental Pulmonary Angiography: Anatomical, Technical and Safety Aspects of a Must-Learn Technique in Times of Balloon Pulmonary Angioplasty for Chronic Thromboembolic Pulmonary Hypertension.

With the advent of balloon pulmonary angioplasty (BPA) for non-surgical chronic thromboembolic pulmonary hypertension (CTEPH) patients, there is renewed interest in the pulmonary angiography technique. This technique is still the standard imaging modality to confirm CTEPH, which, in addition, helps to determine the most appropriate treatment. Furthermore, learning this technique fulfills two main purposes: to identify BPA candidates and to provide the operator with the catheter handling needed to perform BPA. Operators interested in performing BPA must learn not only the pulmonary arteries’ anatomy, but also which are the best angiographic projections and the most suitable catheters to canalize and display each segmental branch. Unfortunately, this information is scarce in the literature. With this goal, learning the diagnostic pulmonary angiography technique can be a first step on the way to perform BPA. Although there are descriptions on how to perform a pulmonary angiography with balloon-tipped catheters and the digital subtraction technique, this technique does not provide operators with the catheter knowledge and manual skill needed to cannulate each segmental branch. In contrast, learning the conventional selective segmental pulmonary angiography (SSPA) technique provides the operator with this knowledge and skills. In this review, based on the experience of the authors, we describe the pulmonary arteries’ anatomy and detail the practical aspects of the SSPA procedure, with the aim of providing operators with the anatomical and technical knowledge needed to perform BPA. We also summarize the contemporary complications of SSPA in CTEPH patients at a reference center.

Prospective cohort study to evaluate narrow diameter implants for restoration of a missing lateral incisor in patients with a cleft palate: One-year results

Statement of problemPatients diagnosed with a cleft palate often have a congenitally missing maxillary lateral incisor. The congenital cleft presents the practitioner with challenges including the quantity and quality of bone, a surgically managed cleft correction, and limited clinical space. PurposeThe purpose of the present prospective investigation was to report preliminary results at the 1-year follow-up for this planned 5-year investigation of narrow diameter implants used to restore a missing lateral incisor in patients with a cleft palate. Material and methodsFourteen study participants with a cleft palate and a missing maxillary lateral incisor were enrolled based on established criteria. Narrow diameter implants (AstraTech OsseoSpeed TX 3.0S and 3.5 mm) were placed by using a 2-stage protocol and restored. All study participants received an Atlantis abutment and a cement-retained crown. Four probing depth measurements and bleeding on probing were measured at baseline and at 1 year. Probing depth measurements were evaluated using a 2-way repeated measures ANOVA with Tukey-Kramer multiple comparisons tests. Radiographic marginal bone loss was measured at 1-year by using a digital subtraction technique and evaluated by using a repeated measures ANOVA. Pretreatment cone beam computed tomography (CBCT) images were used to measure a mean gray level that was proportional to bone mineral density (BMD) in the implant site. One-way mixed ANOVA was used to compare the mean gray level and average implant stability quotient (ISQ) loading. A Pearson correlation was also tested between those parameters (α=.05) for each statistical analysis. ResultsThe mean marginal bone loss at 1 year was 0.601 ±0.48 mm. Regarding probing depth measurements, a 2-way repeated measures ANOVA found both the location (P=.012) and time (P=.009) were significant. The Tukey-Kramer multiple comparisons test showed a significant difference between the buccal and distal site (P=.006) from baseline to 1-year follow-up. ConclusionsNarrow diameter implants are a reliable treatment for replacing a missing lateral incisor in patients with a cleft palate at 1 year, with an implant survival rate of 100% and implant success rate of 94% using the established criteria. A negative association was found between the bone mineral density and the implant stability in the alveolar cleft site of a patient with a cleft palate. The peri-implant soft tissue probe depths exhibited significant change during the first year.

Microsurgical Technique for Treatment of Perimedullary Spinal Arteriovenous Fistulae: 2-Dimensional Operative Video

The case is of a 49-yr-old female admitted after acute onset lower cervical/upper thoracic region pain with left hemi-body hypoesthesia below the C7 level. Magnetic resonance imaging showed a spinal cord intraparenchymal hemorrhage at the C6/7 levels. Physical exam revealed hypoesthesia on the left from C7 and below with associated 3/5 wrist and finger extensor and 4/5 triceps strength on the left. The remainder of the neurological exam was normal including lower extremity strength and bowel/bladder function. A craniocervical angiogram showed a perimedullary arteriovenous fistula on the left, ventrolateral aspect of the spinal cord with a single feeding artery that originated from the thyrocervical trunk and entered through the left C6 nerve root sleeve. Venous drainage was cephalad to cortical cerebellar veins and to the suboccipital plexus. A branch of the thyrocervical trunk supplying the ventral spinal cord originated close to the fistula, which precluded endovascular embolization. The patient underwent C6-T1 laminectomies for microsurgical treatment of the fistula. This case demonstrates multiple key concepts in the surgical management of these rare lesions as follows: the ventral aspect of the cervical spinal cord can be safely approached from posterior. The venous anatomy is often confusing and intraoperative angiography utilizing both indocyanine green and conventional digital subtraction techniques are of paramount importance. Unlike arteriovenous malformations, the venous drainage can be pruned to gain visualization and trace the venous anatomy retrograde to the point of the fistula. The patient awoke from surgery at her neurological baseline. The patient consented to de-identified publication of this case.

Digital Subtraction Air Arthrography: An Innovative Technique for Needle Tip Location Confirmation

PurposeThis article describes an innovative technique to confirm needle tip positioning using digital subtraction fluoroscopy and air within a targeted joint. Materials and MethodsDigital subtraction fluoroscopy with air was utilized to confirm intra-articular needle tip position in 12 joints over a 14-month period at a single institution. Procedural details were recorded for each joint including: joint location, fluoroscopy time, patient age, patient body mass index, and change in subjective pain rating following the injection. Shoulder and hip phantoms were utilized to compare radiation dose differences between fluoroscopy with digital subtraction technique and fluoroscopy without digital subtraction technique. ResultsAll of the 12 injections were technically successful with air clearly visualized within each targeted joint and subjective pain ratings either did not change or decreased following the injection. Patient age ranged from 51 to 87 years old and body mass index values ranged from 19.2 to 37.1 kg/m2. Fluoroscopy times ranged from 11.1 to 32.9 seconds. There were no complications during or immediately following the injections. The addition of digital subtraction technique increased the skin dose at the shoulder by approximately 2.6 times and at the hip by approximately 2.2 times. Likewise, the cumulative dose at the shoulder increased by approximately 2.7 times and at the hip by 2.0 times. ConclusionFluoroscopic digital subtraction air arthrography is a valuable option for needle tip confirmation when using air as a contrast agent. This novel combination of established fluoroscopic techniques can be incorporated into most clinical practices.

Evaluation of the Adaptation of Complete Dentures Fabricated Using Intraoral Scanning and Conventional Techniques

This study aimed to digitally analyze the 3-dimensional variations existing between conventional impressions and intraoral scans made in edentulous maxillae. Ten (n = 10) edentulous maxillae of patients seeking a maxillary complete denture were scanned using an intraoral scanner. The same participants were subject to the conventional impression procedure for the fabrication of maxillary complete dentures. The dentures' intaglio surfaces were scanned and superimposed over their corresponding IOS files with a 2-base best-fit alignment. Deviation analyses were calculated using the digital subtraction technique. Four anatomical regions were preselected to evaluate the deviations at these sites (posterior palatal seal, anterior border seal, the crest of the ridge and palate). Based on the results and color maps of all selected regions, the overall difference between the two scans [IOS and denture intaglio surface scanning (DISS)] was not significant. The IOS technique allowed for predictable outcomes of treatment compared to those observed with conventional impression. The palatal area seems to be the region with the least deviation, while the highest incidence of discrepancy was reported in the anterior border seal. Within the limitations of this study, the IOS technique allowed the capturing of intraoral tissues and their immediate interpretation and transfer to a designing software making the impression procedure faster and easier. The computer-aided design (CAD)/computer-aided manufacturing (CAM) technologies can help overcome many limitations related to conventional impressions and therefore should be well investigated to improve the edentulous patient's quality of life.

Adaptation of Complete Denture Base Fabricated by Conventional, Milling, and 3-D Printing Techniques: An In Vitro Study

The aim of this study was to compare the adaptation of complete denture base (CDB) manufactured by three different techniques: conventional, milling, and three-dimensional (3-D) printing. A master cast was duplicated to create 60 gypsum casts. Twenty casts (n = 20) were attributed to each group. In the computer-aided design and computer-aided manufacturing (CAD/CAM) groups (milling and 3-D printing), the 40 gypsum casts reserved for these two groups were scanned. An STL file was obtained and a master CDB was designed and then fabricated according to each technique. In the conventional group, a polyvinyl siloxane putty mold was obtained from the milled CDB, and this mold was used to fabricate 20 conventional denture bases by compression molding using the silicon-gypsum technique in a bronze flask. The inner surfaces of the obtained 60 CDB were scanned and superimposed over their corresponding master cast. Deviation analyses were calculated using digital subtraction technique. Five functional areas (posterior palatal seal, anterior border seal, crest of the ridge, maxillary tuberosities, and palate) were selected to evaluate the variations in CBD adaptation. Based on the results and color maps of all selected regions, milling technique offers the best adaptation. The crest of ridge in the conventional technique showed the least adaptation and the posterior palatal seal in the 3-D printing technique showed the best adaptation. Within the limitations of this study, the CAD/CAM fabrication techniques seem to offer better adaptation of CDB compared to the conventional fabrication technique. Milled CDBs presented the most homogeneous distribution of adaptation, yet the 3-D printing process seems a promising techniques that needs to be addressed and perfected. The CAD/CAM technologies can help overcome many limitations related to conventional impressions and therefore should be well investigated to improve the edentulous patient's quality of life.

A quantitative wear measurement method on production engine parts: Effect of DLC thin films on wear

The automotive industry is facing worldwide pressure to reduce carbon emission to meet the Paris Accord target of 2 °C increase in global average temperature by the end of the century. One way to reduce carbon emission is to improve fuel economy of cars and trucks. Recent emergence of ultralow viscosity lubricants has shown significant fuel economy benefits. However, the resulting low oil film may cause increased surface contacts and could lead to increased wear. The ability to measure the initiation phase of wear before it accelerates towards failure is an important issue today. Quantitative measurement of wear in engine parts has always been a challenge. In today’s fuel efficient engines, coatings increasingly being introduced into engine component manufacturing, wear metrology of small amount of wear spread over a large area of rough surfaces presents even a greater challenge.This paper describes the development of a quantitative measurement technique to measure mild wear over a relatively large area of rough production engine surfaces. One of the critical engine sliding components is the piston ring vs cross-hatched cylinder liner contact interface. The availability of a quantitative wear measurement technique would allow comparison of various materials, including coated rings, and liner surface treatments. In this study, production rings and liners were obtained from cooperative engine manufacturers under non-disclosure agreements. A reciprocating ring-liner test rig was used to conduct the wear tests, using a newly developed cyclic wear test procedure, sequence of speed and load cycles were used for simulating sliding motions. Mini-cycles (a constant speed with varying loads from 160 N to 240 N) at 120 °C, and at 6 Hz reciprocating frequency were used. An experimental 0 W-16 lubricant, which has gone through engine testing, was used in the wear tests. A dual white light interferometric microscope (Z resolution 1 Å) was used to measure the liner wear. An analytical balance with 1 µg resolution was used to measure the ring segment weight loss. After the wear measurement procedure was established, diamond-like carbon (DLC) coated rings were also used to assess the effect of the DLC on the wear, and the measurement technique. A digital 3D surface topography subtraction technique was successfully developed to measure quantitative wear of the liner. This technique can be used for other wearing engine parts.

A comparison of subtraction MRI with the standard contrast-enhanced imaging in Perthes' disease.

PurposePerthes’ disease (PD) results from loss of blood supply to the hip and can progress to femoral head deformity. MRI in the early course of the disease can provide data on the initial extent of infarct. Vascularity of the femoral head is assessed by gadolinium-enhanced MRI (contrast MRI), which may be improved by the digital subtraction technique (subtraction MRI). We hypothesized that gadolinium-enhanced MRI without subtraction was comparable with subtraction MRI in depicting the femoral head perfusion.MethodsIn all, 34 patients (34 hips) with unilateral PD had gadolinium-enhanced MRI as part of a prospectively randomized study. Nine patients had three MRIs, 15 had two and ten had a single MRI. Measurement of perfusion of the femoral head (MRI perfusion index) was obtained using digital image analysis on all the MRIs, including both before and after subtraction. A paired sample t-test was performed to compare the measurements.ResultsThe mean age of the patients was 8.9 years (sd 1.6). At the time of diagnosis, the subtraction MRI did not elicit a statistically significant difference in MRI perfusion index measurements when compared with the contrast MRI (p = 0.19). The same findings were found when including all patients at various stages of the disease (p = 0.30). Qualitatively, although some subtraction MRI images showed superior delineation of epiphysis, there are no significant differences throughout the whole series.ConclusionAlthough the current literature supports the increasing role of the subtraction MRI for PD management, our study proposed that the contrast MRI without subtraction technique appears adequate in assessing femoral head perfusion.Level of Evidence:Level I - Diagnostic study

Imaging of Cerebral Arteriovenous Malformations and Arteriovenous Fistulas and Occlusion Control Using Intraoperative 3-Dimensional Rotational Fluoroscopy

Intraoperative resection or occlusion control is indispensable in the surgery of vascular anomalies. This can be conducted using local vascular imaging modalities or angiographic techniques. This series was performed to assess whether cerebral arteriovenous malformations (AVMs) and dural arteriovenous fistulae (dAVFs) can be detected in a sufficient quality by intraoperative 3-dimensional (3D) fluoroscopy with intravenous contrast application. Five patients were included in the analysis (2 AVMs, 3 dAVFs). All patients had preoperative digital subtraction angiography. The head was fixed in a carbon MAYFIELD clamp. After a 3D rotational fluoroscopy scan without contrast agent, a second scan with 50 mL of iodine contrast agent was performed. The Digital Imaging and Communications in Medicine data of both scans were subtracted and reconstructed using the OsiriX imaging software. In 2 patients with dAVF, occlusion control was performed after obliteration of the fistula. In the 2 patients with cerebral AVM, 3D fluoroscopy with intravenous contrast administration resulted in good image quality. Preoperative embolization with Onyx produces significant artifacts that can be largely removed by simple digital subtraction techniques. In dural AVF, occlusion control was well feasible after obliteration of the draining vein at its dural origin. This technique quickly supplies intraoperative images of adequate quality to locate cerebral AVM and dAVF. However, it does not produce dynamic images. Thus, early draining veins cannot be located unless anatomically identified based on the preoperative DSA. In this case, it can be used for intraoperative obliteration control.

Optic Disc Image Subtraction as an Aid to Detect Glaucoma Progression.

PurposeTo present a digital image subtraction technique to alert clinicians to signs of glaucomatous optic disc progression.MethodsNinety-two glaucomatous eyes (65 patients) were included. Thirty-three eyes were identified as progressive and 59 as stable based on comparison of baseline and follow-up stereoscopic disc photographs by three masked glaucoma specialists. The disc images were aligned and converted to gray scale and underwent histogram matching to enhance contrast and account for illumination differences. The difference in image intensity between baseline and follow-up images was shown as a colormap superimposed on the grayscale follow-up image. A graded scale (1, no progression, to 5, definitive progression) was used by three masked glaucoma experts to score progression probability on the colormap images. Sensitivity, specificity, and accuracy of the classification were computed. Weighted κ statistics summarized agreement of categorical gradings.ResultsMedian time interval between two visits was 4.4 years (range: 1.0–16.8). Clinicians detected glaucoma deterioration in 25 to 27 of the progressive group and 8 to 10 of stable eyes based on subtraction maps. Sensitivities/specificities of the clinicians were 0.76 to 0.82 and 0.86 to 0.89, respectively. Classification accuracy ranged from 81.5% to 84.8%. Agreement among clinicians was good (weighted κ = 0.68; 95% confidence interval [CI]: 0.60–0.77) for progression grades (1–5 scales) and was substantial (weighted κ = 0.81; 95% CI: 0.74–0.85) for binary scores.ConclusionsThe proposed software provides a single static image that clinicians can use with other structural/functional tests to detect glaucoma progression.Translational RelevanceProvision of a subtraction colormap in the setting of electronic medical records can improve monitoring of glaucoma by alerting clinicians to possible signs of progression.

3D-printing zirconia implants; a dream or a reality? An in-vitro study evaluating the dimensional accuracy, surface topography and mechanical properties of printed zirconia implant and discs.

The aim of this study was to evaluate the dimensional accuracy, surface topography of a custom designed, 3D-printed zirconia dental implant and the mechanical properties of printed zirconia discs. A custom designed implant was 3D-printed in zirconia using digital light processing technique (DLP). The dimensional accuracy was assessed using the digital-subtraction technique. The mechanical properties were evaluated using biaxial flexure strength test. Three different build angles were adopted to print the specimens for the mechanical test; 0°(Vertical), 45° (Oblique) and 90°(Horizontal) angles. The surface topography, crystallographic phase structure and surface roughness were evaluated using scanning electron microscopy analysis (SEM), X-ray diffractometer and confocal microscopy respectively. The printed implant was dimensionally accurate with a root mean square (RMSE) value of 0.1mm. The Weibull analysis revealed a statistically significant higher characteristic strength (1006.6MPa) of 0° printed specimens compared to the other two groups and no significant difference between 45° (892.2MPa) and 90° (866.7MPa) build angles. SEM analysis revealed cracks, micro-porosities and interconnected pores ranging in size from 196nm to 3.3µm. The mean Ra (arithmetic mean roughness) value of 1.59µm (±0.41) and Rq (root mean squared roughness) value of 1.94µm (±0.47) was found. A crystallographic phase of primarily tetragonal zirconia typical of sintered Yttria tetragonal stabilized zirconia (Y-TZP) was detected. DLP prove to be efficient for printing customized zirconia dental implants with sufficient dimensional accuracy. The mechanical properties showed flexure strength close to those of conventionally produced ceramics. Optimization of the 3D-printing process parameters is still needed to improve the microstructure of the printed objects.

Build Angle: Does It Influence the Accuracy of 3D-Printed Dental Restorations Using Digital Light-Processing Technology?

The aim of this study was to evaluate the effect of the build orientation/build angle on the dimensional accuracy of full-coverage dental restorations manufactured using digital light-processing technology (DLP-AM). A full dental crown was digitally designed and 3D-printed using DLP-AM. Nine build angles were used: 90, 120, 135, 150, 180, 210, 225, 240, and 270 degrees. The specimens were digitally scanned using a high-resolution optical surface scanner (IScan D104i, Imetric). Dimensional accuracy was evaluated using the digital subtraction technique. The 3D digital files of the scanned printed crowns (test model) were exported in standard tessellation language (STL) format and superimposed on the STL file of the designed crown [reference model] using Geomagic Studio 2014 (3D Systems). The root mean square estimate (RMSE) values were evaluated, and the deviation patterns on the color maps were further assessed. The build angle influenced the dimensional accuracy of 3D-printed restorations. The lowest RMSE was recorded for the 135-degree and 210-degree build angles. However, the overall deviation pattern on the color map was more favorable with the 135-degree build angle in contrast with the 210-degree build angle where the deviation was observed around the critical marginal area. Within the limitations of this study, the recommended build angle using the current DLP system was 135 degrees. Among the selected build angles, it offers the highest dimensional accuracy and the most favorable deviation pattern. It also offers a self-supporting crown geometry throughout the building process.

Periodontal Kemik Defektlerinin Varlığı ve Bukkal-Lingual Lokalizasyonlarının Belirlenmesinde Farklı İntraoral Görüntüleme Yöntemleri ile Dijital Subtraksiyon Tekniğinin Etkinliklerinin Karşılaştırılması

Periodontal Kemik Defektlerinin Varlığı ve Bukkal-Lingual Lokalizasyonlarının Belirlenmesinde Farklı İntraoral Görüntüleme Yöntemleri ile Dijital Subtraksiyon Tekniğinin Etkinliklerinin Karşılaştırılması

Extended-Thoracic Imaging of Multi-slice Computed Tomography Technique in the Evaluation of Hemoptysis Resulting from Neoplastic Lesions: Two Cases Study

Objective: This study aimed to evaluate the role of multi-detectors computed tomography in patients suffering from hemoptysis, resulting from neoplastic lesions, and aiming to reach proper diagnosis and subsequent proper management. Methods: This study was carried out on consecutive 13 patients suffering from hemoptysis resulting from malignant thoracic lesions. All patients were subject to complete clinical assessment, laboratory study, roentgen graphic study including Plain chest X-Ray and Multidetector Computed Tomography (MDCT), Multidetector Computed Tomography Angiography (MDCTA), Minimum intensity projection (MIP), 3D volume –rendering images and Virtual Bronchoscopy (VB). VB was also compared with the report of Fiber-optic Bronchoscopy (FOB). Conventional Angiography was performed in selected indicated patients with a digital subtraction technique (DSA). (2 patients only). Results: 9 male (70%), and 4 female (30%). Based on clinical chest X-RAY, MDCT, DSA , FOB and Histopathology , a source and etiology for bleeding could be identified applying a diagnostic work up in 12 /13 (92%). Plain radiography was considered successfully contributing in the identification of the cause of hemoptysis in only 38.5% of patients. CT angiography showed enlarged tortuous bronchial feeding vessels in 42% of patients. Bleeding from pulmonary artery was identified in 20%. DSA was performed in 2 patients 15%, indicated for embolization. Fibrooptic bronchoscopy findings were evaluated in 13/13 patients with histopathological confirmation in 12 patients. Conclusion: The study concluded that MDCT using VB is considered a primary non-invasive imaging modality in the evaluation of patients with hemoptysis resulting from neoplastic lesions.

Dual-phase post-mortem digital subtraction CT angiography: Color encoded demonstration of the arterial and venous phases

Whole-body post-mortem CT angiography usually is performed in two phases: in most cases first an arterial phase is performed, followed by a venous phase. Therefore in the arterial phase only the contrast medium in the arterial side of the vascular system (plus extravasations) is displayed while in the venous phase there is a superposition of contrast medium in the arterial and the venous side of the vascular system (plus extravasations). Digital subtraction techniques can be used to perform bone removal and to obtain a “venous phase only” image.

インプラント体周囲の顎骨変化に関するデジタルサブトラクション法による エックス線学的定量分析：一次手術から二次手術までの骨レベルの変化について

インプラント体周囲の顎骨変化に関するデジタルサブトラクション法による エックス線学的定量分析：一次手術から二次手術までの骨レベルの変化について