Image quality of supine chest radiographs: intra-individual comparison of computed radiography and low-dose linear-slit digital radiography

The purpose of this retrospective study was to intra-individually compare the image quality of computed radiography (CR) and low-dose linear-slit digital radiography (LSDR) for supine chest radiographs. A total of 90 patients (28 female, 62 male; mean age, 55.1 years) imaged with CR and LSDR within a mean time interval of 2.8 days +/- 3.0 were included in this study. Two independent readers evaluated the image quality of CR and LSDR based on modified European Guidelines for Quality Criteria for chest X-ray. The Wilcoxon test was used to analyse differences between the techniques. The overall image quality of LSDR was significantly better than the quality of CR (9.75 vs 8.16 of a maximum score of 10; p < 0.001). LSDR performed significantly better than CR for delineation of anatomical structures in the mediastinum and the retrocardiac lung (p < 0.001). CR was superior to LSDR for visually sharp delineation of the lung vessels and the thin linear structures in the lungs. We conclude that LSDR yields better image quality and may be more suitable for excluding significant pathological features of the chest in areas with high attenuation compared with CR.

Characteristics and dimensions of the sinus membrane in patients referred for single-implant treatment in the posterior maxilla: a cone beam computed tomographic analysis

PURPOSE The purpose of the present study was to evaluate the thickness and anatomic characteristics of the sinus membrane using cone beam computed tomography (CBCT) in patients evaluated for implant surgery in the posterior maxilla. MATERIALS AND METHODS The study included 131 consecutive patients referred for dental implant placement in the posterior maxilla. A total of 138 CBCT images was obtained using fields of view of 4 × 4 cm, 6 × 6 cm, or 8 × 8 cm. Reformatted sagittal CBCT slices were analyzed with regard to the thickness and characteristics of the sinus membrane at single-tooth gaps in the posterior maxilla. Factors that might influence the dimensions of the sinus membrane, such as age, sex, endodontic status, and the season, were analyzed. RESULTS The mean thickness of the maxillary sinus mucosa varied between 2.1 and 2.69 mm in the three locations analyzed. Fewer than half of the evaluated sinuses exhibited a healthy mucosa (49 of 138, or 35.51%). Most of the pathologic findings were flat, shallow thickenings (63 of 138, or 45.65%). Sex did not influence the thickness of the sinus membrane at the root tips of the premolars or at single-tooth gaps, but there was a statistically significant correlation in the region of the maxillary molars. No other evaluated factors had a statistically significant effect on the dimensions of the antral mucosa. CONCLUSIONS In the present study, sex was the only factor influencing the dimension of the sinus membrane, whereas patient age, season, and the endodontic status of neighboring teeth had no significant effect on the thickness of the antral mucosa. Future studies should address which types of mucosal thickening require interdisciplinary therapy.

Cone Beam and Micro-Computed Tomography Validation of Manual Array Insertion for Minimally Invasive Cochlear Implantation

Delivering cochlear implants through a minimally invasive tunnel (1.8 mm in diameter) from the mastoid surface to the inner ear is referred to as direct cochlear access (DCA). Based on cone beam as well as micro-computed tomography imaging, this in vitro study evaluates the feasibility and efficacy of manual cochlear electrode array insertions via DCA. Free-fitting electrode arrays were inserted in 8 temporal bone specimens with previously drilled DCA tunnels. The insertion depth angle, procedural time, tunnel alignment as well as the inserted scala and intracochlear trauma were assessed. Seven of the 8 insertions were full insertions, with insertion depth angles higher than 520°. Three cases of atraumatic scala tympani insertion, 3 cases of probable basilar membrane rupture and 1 case of dislocation into the scala vestibuli were observed (1 specimen was damaged during extraction). Manual electrode array insertion following a DCA procedure seems to be feasible and safe and is a further step toward clinical application of image-guided otological microsurgery.

Impacted maxillary canines and root resorptions of neighbouring teeth: a radiographic analysis using cone-beam computed tomography

The study analyses the location of impacted maxillary canines and factors influencing root resorptions of adjacent teeth using cone-beam computed tomography (CBCT). In addition, the interrater reliability between observers of two different dental specialties for radiographic parameters will be evaluated. CBCT images of patients who were referred for radiographic localization of impacted maxillary canines and/or suspicion of root resorptions of adjacent teeth were included. The study analysed the exact three-dimensional location of the impacted canines in the anterior maxilla, frequency and extent of root resorptions, and potential influencing factors. To assess interrater agreement, Cohen's correlation parameters were calculated. This study comprises 113 patients with CBCT scans, and 134 impacted canines were analysed retrospectively. In the patients evaluated, 69 impacted canines were located palatally (51.49 per cent), 41 labially (30.60 per cent), and 24 (17.91 per cent) in the middle of the alveolar process. Root resorptions were found in 34 lateral incisors (25.37 per cent), 7 central incisors (5.22 per cent), 6 first premolars (4.48 per cent), and 1 second premolar (0.75 per cent). There was a significant correlation between root resorptions on adjacent teeth and localization of the impacted canine in relation to the bone, as well as vertical localization of the canine. Interrater agreement showed values of 0.546-0.877. CBCT provides accurate information about location of the impacted canine and prevalence and degree of root resorption of neighbouring teeth with high interrater correlation. This information is of great importance for surgeons and orthodontists for accurate diagnostics and interdisciplinary treatment planning.

Experimental characterization of cement–bentonite interaction using core infiltration techniques and 4D computed tomography

Deep geological storage of radioactive waste foresees cementitious materials as reinforcement of tunnels and as backfill. Bentonite is proposed to enclose spent fuel drums, and as drift seals. The emplacement of cementitious material next to clay material generates an enormous chemical gradient in pore water composition that drives diffusive solute transport. Laboratory studies and reactive transport modeling predict significant mineral alteration at and near interfaces, mainly resulting in a decrease of porosity in bentonite. The goal of this project is to characterize and quantify the cement/bentonite skin effects spatially and temporally in laboratory experiments. A newly developed mobile X-ray transparent core infiltration device was used, which allows performing X-ray computed tomography (CT) periodically without interrupting a running experiment. A pre-saturated cylindrical MX-80 bentonite sample (1920 kg/m3 average wet density) is subjected to a confining pressure as a constant total pressure boundary condition. The infiltration of a hyperalkaline (pH 13.4), artificial OPC (ordinary Portland cement) pore water into the bentonite plug alters the mineral assemblage over time as an advancing reaction front. The related changes in X-ray attenuation values are related to changes in phase densities, porosity and local bulk density and are tracked over time periodically by non-destructive CT scans.

Illusions of fusions: assessing cervical vertebral fusion on lateral cephalograms, multidetector computed tomographs, and cone-beam computed tomographs

INTRODUCTION The aims of this study were to compare lateral cephalograms with other radiologic methods for diagnosing suspected fusions of the cervical spine and to validate the assessment of congenital fusions and osteoarthritic changes against the anatomic truth. METHODS Four cadaver heads were selected with fusion of vertebrae C2 and C3 seen on a lateral cephalogram. Multidetector computed tomography (MDCT) and cone-beam computed tomography (CBCT) were performed and assessed by 5 general radiologists and 5 oral radiologists, respectively. Vertebrae C2 and C3 were examined for osseous fusions, and the left and right facet joints were diagnosed for osteoarthritis. Subsequently, the C2 and C3 were macerated and appraised by a pathologist. Descriptive analysis was performed, and interrater agreements between and within the groups were computed. RESULTS All macerated specimens showed osteoarthritic findings of varying degrees, but no congenital bony fusion. All observers agreed that no fusion was found on MDCT or CBCT. They disagreed on the prevalence of osteoarthritic deformities (general radiologists/MDCT, 100%; oral radiologists/CBCT, 93.3%) and joint space assessment in the facet joints (kappa = 0.452). The agreement within the rater groups differed considerably (general radiologists/MDCT, kappa = 0.612; oral radiologists/CBCT, kappa = 0.240). CONCLUSIONS Lateral cephalograms do not provide dependable data to assess the cervical spine for fusions and cause false-positive detections. Both MDCT interpreted by general radiologists and CBCT interpreted by oral radiologists are reliable methods to exclude potential fusions. Degenerative osteoarthritic changes are diagnosed more accurately and consistently by general radiologists evaluating MDCT.

Location and dimensions of the mental foramen: a radiographic analysis by using cone-beam computed tomography

INTRODUCTION The mental foramen (MF) is an important landmark in dentistry. Knowledge of its position is central to perform block anesthesia of the mental nerve or to avoid nerve damage during surgical procedures in the premolar area of the mandible. The present radiographic study aimed at evaluating the location and dimension of the MF and measuring distances to neighboring structures by using limited cone-beam computed tomography (CBCT). METHODS Sagittal, axial, and coronal CBCT images of 142 patients (26 bilateral and 116 unilateral cases) were retrospectively screened to determine the location of the MF with respect to adjacent teeth and to take linear measurements of the size of the MF and its distances to the upper and lower borders of the mandible. In addition, the course and angulation of the mental canal exiting the MF were assessed. RESULTS The majority of MF (56%) were located apically between the 2 premolars, and another 35.7% of MF were positioned below the second premolar. On average, the MF was localized 5.0 mm from the closest root of the adjacent tooth (range, 0.3-9.8 mm). The mean size of the MF showed a height of 3.0 mm and a length of 3.2 mm; however, individual cases showed large differences in height (1.8-5.1 mm) and in length (1.8-5.5 mm). All mental canals exiting the MF demonstrated an upward course in the coronal plane, with 70.1% of the mental canal presenting an anterior loop (AL) in the axial view. The mean extension of AL in cases with an AL was 2.3 mm. CONCLUSIONS This study is consistent with previous radiographic studies regarding size and location of MF and distances between MF and adjacent anatomic structures. The assessed bilateral cases showed a high intraindividual concordance for certain features when comparing right and left sides.

[Cone beam computed tomography in endodontics: a review for daily clinical practice]

Since the introduction of cone beam computed tomography (CBCT), this 3-dimensional diagnostic imaging technique has been established in a growing number of fields in dental medicine. It has become an important tool for both diagnosis and treatment planning, and is also able to support endodontic treatments. However, the higher effective dose of ionizing radiation compared to conventional 2-dimensional radiographs is not justifiable in every case. CBCT allows for a more precise diagnosis of periapical lesions, root fractures as well as external and internal resorptions. Concerning the utility of CBCT in treatment planning decisions, the gain of information through 3-dimensional imaging for any of these pathologies has to be evaluated carefully on an individual basis. Moreover, radioopaque materials such as root canal filling and posts often create artefacts, which may compromise diagnosis. The aim of this review is to summarize the possibilities and limits of CBCT imaging in endodontology as well as introduce guidelines for daily clinical practice. Furthermore, the article presents possible therapeutic advantages of preexisting CBCT scans for root canal treatments.

Assessment of bone channels other than the nasopalatine canal in the anterior maxilla using limited cone beam computed tomography

PURPOSE The anterior maxilla, sometimes also called premaxilla, is an area frequently requiring surgical interventions. The objective of this observational study was to identify and assess accessory bone channels other than the nasopalatine canal in the anterior maxilla using limited cone beam computed tomography (CBCT). METHODS A total of 176 cases fulfilled the inclusion criteria comprising region of interest, quality of CBCT image, and absence of pathologic lesions or retained teeth. Any bone canal with a minimum diameter of 1.00 mm other than the nasopalatine canal was analyzed regarding size, location, and course, as well as patient gender and age. RESULTS A total of 67 accessory canals ≥1.00 mm were found in 49 patients (27.8%). A higher frequency of accessory canals was observed in males (33.0%) than in females (22.7%) (p = 0.130). Accessory canals occurred more frequently in older rather than younger patients (p = 0.115). The mean diameter of accessory canals was 1.31 ± 0.26 mm (range 1.01-2.13 mm). Gender and age did not significantly influence the diameter. Accessory canals were found palatal to all anterior teeth, but most frequently palatal to the central incisors. In 56.7%, the accessory canals curved superolaterally and communicated with the ipsilateral alveolar extension of the canalis sinuosus. CONCLUSIONS The study confirms the presence of bone channels within the anterior maxilla other than the nasopalatine canal. More than half of these accessory bone canals communicated with the canalis sinuosus. From a clinical perspective, studies are needed to determine the content of these accessory canals.

Accuracy and reproducibility of aortic annulus sizing using a dedicated three-dimensional computed tomography reconstruction tool in patients evaluated for transcatheter aortic valve replacement

Aims: To evaluate the accuracy and reproducibility of aortic annulus sizing using a multislice computed tomography (MSCT) based aortic root reconstruction tool compared with conventional imaging among patients evaluated for transcatheter aortic valve replacement (TAVR). Methods and results: Patients referred for TAVR underwent standard preprocedural assessment of aortic annulus parameters using MSCT, angiography and transoesophageal echocardiography (TEE). Three-dimensional (3-D) reconstruction of MSCT images of the aortic root was performed using 3mensio (3mensio Medical Imaging BV, Bilthoven, The Netherlands), allowing for semi-automated delineation of the annular plane and assessment of annulus perimeter, area, maximum, minimum and virtual diameters derived from area and perimeter (aVD and pVD). A total of 177 patients were enrolled. We observed a good inter-observer variability of 3-D reconstruction assessments with concordance coefficients for agreement of 0.91 (95% CI: 0.87-0.93) and 0.91 (0.88-0.94) for annulus perimeter and area assessments, respectively. 3-D derived pVD and aVD correlated very closely with a concordance coefficient of 0.97 (0.96-0.98) with a mean difference of 0.5±0.3 mm (pVD-aVD). 3-D derived pVD showed the best, but moderate concordance with diameters obtained from coronal MSCT (0.67, 0.56-0.75; 0.3±1.8 mm), and the lowest concordance with diameters obtained from TEE (0.42, 0.31-0.52; 1.9±1.9 mm). Conclusions: MSCT-based 3-D reconstruction of the aortic annulus using the 3mensio software enables accurate and reproducible assessment of aortic annulus dimensions.

Regional myocardial wall thinning at multidetector computed tomography correlates to arrhythmogenic substrate in postinfarction ventricular tachycardia: assessment of structural and electrical substrate

BACKGROUND A majority of patients undergoing ablation of ventricular tachycardia have implanted devices precluding substrate imaging with delayed-enhancement MRI. Contrast-enhanced multidetector computed tomography (MDCT) can depict myocardial wall thickness with submillimetric resolution. We evaluated the relationship between regional myocardial wall thinning (WT) imaged by MDCT and arrhythmogenic substrate in postinfarction ventricular tachycardia. METHODS AND RESULTS We studied 13 consecutive postinfarction patients undergoing MDCT before ablation. MDCT data were integrated with high-density 3-dimensional electroanatomic maps acquired during sinus rhythm (endocardium, 509±291 points/map; epicardium, 716±323 points/map). Low-voltage areas (<1.5 mV) and local abnormal ventricular activities (LAVA) during sinus rhythm were assessed with regard to the WT. A significant correlation was found between the areas of WT <5 mm and endocardial low voltage (correlation-R=0.82; P=0.001), but no such correlation was found in the epicardium. The WT <5 mm area was smaller than the endocardial low-voltage area (54 cm(2) [Q1-Q3, 46-92] versus 71 cm(2) [Q1-Q3, 59-124]; P=0.001). Among a total of 13 060 electrograms reviewed in the whole study population, 538 LAVA were detected and analyzed. LAVA were located within the WT <5 mm (469/538 [87%]) or at its border (100% within 23 mm). Very late LAVA (>100 ms after QRS complex) were almost exclusively detected within the thinnest area (93% in the WT<3 mm). CONCLUSIONS Regional myocardial WT correlates to low-voltage regions and distribution of LAVA critical for the generation and maintenance of postinfarction ventricular tachycardia. The integration of MDCT WT with 3-dimensional electroanatomic maps can help focus mapping and ablation on the culprit regions, even when MRI is precluded by the presence of implanted devices.

Integration of merged delayed-enhanced magnetic resonance imaging and multidetector computed tomography for the guidance of ventricular tachycardia ablation: a pilot study

BACKGROUND Delayed enhancement (DE) MRI can assess the fibrotic substrate of scar-related VT. MDCT has the advantage of inframillimetric spatial resolution and better 3D reconstructions. We sought to evaluate the feasibility and usefulness of integrating merged MDCT/MRI data in 3D-mapping systems for structure-function assessment and multimodal guidance of VT mapping and ablation. METHODS Nine patients, including 3 ischemic cardiomyopathy (ICM), 3 nonischemic cardiomyopathy (NICM), 2 myocarditis, and 1 redo procedure for idiopathic VT, underwent MRI and MDCT before VT ablation. Merged MRI/MDCT data were integrated in 3D-mapping systems and registered to high-density endocardial and epicardial maps. Low-voltage areas (<1.5 mV) and local abnormal ventricular activities (LAVA) during sinus rhythm were correlated to DE at MRI, and wall-thinning (WT) at MDCT. RESULTS Endocardium and epicardium were mapped with 391 ± 388 and 1098 ± 734 points per map, respectively. Registration of MDCT allowed visualization of coronary arteries during epicardial mapping/ablation. In the idiopathic patient, integration of MRI data identified previously ablated regions. In ICM patients, both DE at MRI and WT at MDCT matched areas of low voltage (overlap 94 ± 6% and 79 ± 5%, respectively). In NICM patients, wall-thinning areas matched areas of low voltage (overlap 63 ± 21%). In patients with myocarditis, subepicardial DE matched areas of epicardial low voltage (overlap 92 ± 12%). A total number of 266 LAVA sites were found in 7/9 patients. All LAVA sites were associated to structural substrate at imaging (90% inside, 100% within 18 mm). CONCLUSION The integration of merged MDCT and DEMRI data is feasible and allows combining substrate assessment with high-spatial resolution to better define structure-function relationship in scar-related VT.

Ligament origins are preserved in distal radial intraarticular two-part fractures: a computed tomography-based study

Background Operative fixation of intraarticular distal radius fractures is increasingly common. A greater understanding of fracture patterns will aid surgical fixation strategy. Previous studies have suggested that ligamentous insertions may less commonly be involved, but these have included heterogeneous groups of fractures and have not addressed Lister's tubercle. Purpose We hypothesize that fracture lines of distal radial intraarticular 2-part fractures have reproducible patterns. They propagate through the cortical bone between ligament origins and do not involve Lister's tubercle. Methods Axial CT scans of two-part intraarticular distal radius fractures were assessed independently by two examiners. The fractures were mapped onto a grid and the cortical breaches expressed as a percentile of the total radial width or length. The cortical breaches were compared with the ligamentous insertions on the distal and Lister's tubercle. Associated injuries were also documented. Results The cortical breaches occurred between the ligamentous insertions in 85%. Lister's tubercle was not involved in 95% of the fractures. Three major fracture patterns emerged: radial styloid, dorsal, and volar. Each major pattern had two subtypes. Associated injuries were common. Scapholunate dissociation was associated with all types, not just the radial styloid fracture pattern. Conclusions The fracture patterns of two-part intraarticular fractures mostly involved the interligamentous zones. Three major groups were identified: dorsal, volar, and radial styloid. Lister's tubercle was preserved with fractures tending to propagate radial or ulnar to this structure. We suggest conceptualizing fracture fragments as osseo-ligamentous units to aid prediction of fracture patterns and associated injury. Study Design Diagnostic III Level of Evidence 3.

Human intervertebral disc stiffness correlates better with the Otsu threshold computed from axial T2 map of its posterior annulus fibrosus than with clinical classifications

Degeneration of the intervertebral disc, sometimes associated with low back pain and abnormal spinal motions, represents a major health issue with high costs. A non-invasive degeneration assessment via qualitative or quantitative MRI (magnetic resonance imaging) is possible, yet, no relation between mechanical properties and T2 maps of the intervertebral disc (IVD) has been considered, albeit T2 relaxation time values quantify the degree of degeneration. Therefore, MRI scans and mechanical tests were performed on 14 human lumbar intervertebral segments freed from posterior elements and all soft tissues excluding the IVD. Degeneration was evaluated in each specimen using morphological criteria, qualitative T2 weighted images and quantitative axial T2 map data and stiffness was calculated from the load-deflection curves of in vitro compression, torsion, lateral bending and flexion/extension tests. In addition to mean T2, the OTSU threshold of T2 (TOTSU), a robust and automatic histogram-based method that computes the optimal threshold maximizing the distinction of two classes of values, was calculated for anterior, posterior, left and right regions of each annulus fibrosus (AF). While mean T2 and degeneration schemes were not related to the IVDs' mechanical properties, TOTSU computed in the posterior AF correlated significantly with those classifications as well as with all stiffness values. TOTSU should therefore be included in future degeneration grading schemes.