Short Scan Research Articles

Angle prediction model when the imaging plane is tilted about z-axis.

Computer Tomography (CT) is a complicated imaging system, requiring highly geometric positioning. We found a special artifact caused by detection plane tilted around z-axis. In short scan cone-beam reconstruction, this kind of geometric deviation result in half circle shaped fuzzy around highlighted particles in reconstructed slices. This artifact is distinct near the slice periphery, but deficient around the slice center. We generated mathematical models, and InceptionV3-R deep network to study the slice artifact features to estimate the detector z-axis tilt angle. The testing results are: mean absolute error of 0.08819 degree, the Root mean square error of 0.15221 degree and R-square of 0.99944. A geometric deviation recover formula was deduced, which can eliminate this artifact efficiently. This research enlarges the CT artifact knowledge hierarchy, and verifies the capability of machine learning in CT geometric deviation artifact recoveries.

Scan-Specific Generative Neural Network for MRI Super-Resolution Reconstruction.

The interpretation and analysis of Magnetic resonance imaging (MRI) benefit from high spatial resolution. Unfortunately, direct acquisition of high spatial resolution MRI is time-consuming and costly, which increases the potential for motion artifact, and suffers from reduced signal-to-noise ratio (SNR). Super-resolution reconstruction (SRR) is one of the most widely used methods in MRI since it allows for the trade-off between high spatial resolution, high SNR, and reduced scan times. Deep learning has emerged for improved SRR as compared to conventional methods. However, current deep learning-based SRR methods require large-scale training datasets of high-resolution images, which are practically difficult to obtain at a suitable SNR. We sought to develop a methodology that allows for dataset-free deep learning-based SRR, through which to construct images with higher spatial resolution and of higher SNR than can be practically obtained by direct Fourier encoding. We developed a dataset-free learning method that leverages a generative neural network trained for each specific scan or set of scans, which in turn, allows for SRR tailored to the individual patient. With the SRR from three short duration scans, we achieved high quality brain MRI at an isotropic spatial resolution of 0.125 cubic mm with six minutes of imaging time for T2 contrast and an average increase of 7.2 dB (34.2%) in SNR to these short duration scans. Motion compensation was achieved by aligning the three short duration scans together. We assessed our technique on simulated MRI data and clinical data acquired from 15 subjects. Extensive experimental results demonstrate that our approach achieved superior results to state-of-the-art methods, while in parallel, performed at reduced cost as scans delivered with direct high-resolution acquisition.

Comparison and Review of DAT Scan, PET Scan, and α-synuclein In Relation to Parkinson’s Disease

In this article, the role of the Dopamine Active Transporter (DAT) scan, and Positron Emission Tomography (PET) scan along with the role of α-synuclein with regards to Parkinson’s disease will be discussed. Furthermore, their applications and dependence as diagnostic techniques, as well as biomarkers, are also reviewed. In short, DAT-SPECT and PET scans can be used well to differentiate between Parkinson’s and other Parkinsonian syndromes, but it takes experts with many years of experience to help with diagnosis. Ɑ-synuclein on the other hand may not serve as a good biomarker but it does have potential in therapeutic treatments.
 Furthermore, a few common diseases that are most often misdiagnosed with Parkinson’s are also discussed. They include Multiple Sclerosis (MS) and Progressive Supranuclear Palsy. MS deals with the degeneration of the myelin sheath which PSP deals with the build-up of a certain protein in the brain called tau. In both cases, neuronal degeneration occurs, similar to what happens with respect to Parkinson’s. Unfortunately, there is no current cure for Parkinson’s, PSP, or MS. 
 Lastly, this paper also reviews the author's future plans with regard to Parkinson’s disease and other neurodegenerative diseases in general. There is a dire need for biomarkers and/or a concrete diagnostic technique that can detect Parkinson’s earlier such that progression is either delayed or treatment is developed based on this.

Experimental Study on the Characterization of Orientation of Polyester Short Fibers in Rubber Composites by an X-ray Three-Dimensional Microscope.

Polyester-short-fiber-reinforced rubber composites have been detected by an X-ray three-dimensional microscope, and then the three-dimensional reconstruction of the image has been carried out to characterize the orientation of polyester short fibers in the composites for the first time. Based on the summary of three traditional methods and mechanisms of characterizing the orientation of polyester short fibers by the numerical parameter method, the direct test method, and the indirect test method, the method and mechanism of the X-ray three-dimensional microscope applied to the orientation characterization of polyester short fibers have been studied. The combination of the center point and threshold segmentation methods has been used to distinguish which fiber section belongs to the same fiber, and the identification of the whole short fiber in different slice images has been realized for the first time. Moreover, Avizo software has been used to realize the three-dimensional reconstruction of a polyester short fiber scanning image. The obtained data have been integrated and the orientation angle and orientation degree have been quantitatively characterized for the first time. This has filled the key technical problem of quantitative characterization of the orientation angle and orientation degree of polyester fibers. The image has been verified by 3Dmed software, and furthermore, the accuracy of the three-dimensional reconstruction results has been verified.

Improved Clinical Workflow for Whole-Body Patlak Parametric Imaging Using Two Short Dynamic Acquisitions.

ObjectiveWe sought to explore the feasibility of shorter acquisition times using two short dynamic scans for a multiparametric PET study and the influence of quantitative performance in shortened dynamic PET.MethodsTwenty-one patients underwent whole-body dynamic 18F-FDG PET/CT examinations on a PET/CT (Siemens Biograph Vision) with a total scan time of 75 min using continuous bed motion for Patlak multiparametric imaging. Two sets of Patlak multiparametric images were produced: the standard MRFDG and DVFDG images (MRFDG-std and DVFDG-std) and two short dynamic MRFDG and DVFDG images (MRFDG-tsd and DVFDG-tsd), which were generated by a 0–75 min post injection (p.i.) dynamic PET series and a 0–6 min + 60–75 min p.i. dynamic PET series, respectively. The maximum, mean, and peak values of the standard and two short dynamic multiparametric acquisitions were obtained and compared using Passing–Bablok regression and Bland–Altman analysis.ResultsHigh correlations were obtained between MRFDG-tsd and MRFDG-std, and between DVFDG-tsd and DVFDG-std for both normal organs and all lesions (0.962 ≦ Spearman’s rho ≦ 0.982, p < 0.0001). The maximum, mean, and peak values of the standard and two short dynamic multiparametric acquisitions were also in agreement. For normal organs, the Bland–Altman plot showed that the mean bias of MRFDG-max, MRFDG-mean, and MRFDG-peak was -0.002 (95% CI: -0.032–0.027), -0.002 (95% CI: -0.026–0.023), and -0.002 (95% CI: -0.026–0.022), respectively. The mean bias of DVFDG-max, DVFDG-mean, and DVFDG-peak was -3.3 (95% CI: -24.8–18.2), -1.4 (95% CI: -12.1–9.2), and -2.3 (95% CI: -15–10.4), respectively. For lesions, the Bland–Altman plot showed that the mean bias of MRFDG-max, MRFDG-mean, and MRFDG-peak was -0.009 (95% CI: -0.056–0.038), -0.004 (95% CI: -0.039–0.031), and -0.004 (95% CI: -0.036–0.028), respectively. The mean bias of DVFDG-max, DVFDG-mean, and DVFDG-peak was -8.4 (95% CI: -42.6–25.9), -4.8 (95% CI: -20.2–10.6), and -4.0 (95% CI: -23.7–15.6), respectively.ConclusionsThis study demonstrates the feasibility of using two short dynamic scans that include the first 0–6 min and 60–75 min scans p.i. for Patlak multiparametric images, which can increase patient throughout for parametric analysis.

Sparse Angle CBCT Reconstruction Based on Guided Image Filtering.

Cone-beam Computerized Tomography (CBCT) has the advantages of high ray utilization and detection efficiency, short scan time, high spatial and isotropic resolution. However, the X-rays emitted by CBCT examination are harmful to the human body, so reducing the radiation dose without damaging the reconstruction quality is the key to the reconstruction of CBCT. In this paper, we propose a sparse angle CBCT reconstruction algorithm based on Guided Image FilteringGIF, which combines the classic Simultaneous Algebra Reconstruction Technique(SART) and the Total p-Variation (TpV) minimization. Due to the good edge-preserving ability of SART and noise suppression ability of TpV minimization, the proposed method can suppress noise and artifacts while preserving edge and texture information in reconstructed images. Experimental results based on simulated and real-measured CBCT datasets show the advantages of the proposed method.

Interobserver Reliability on Intravoxel Incoherent Motion Imaging in Patients with Acute Ischemic Stroke.

Noninvasive perfusion-weighted imaging with short scanning time could be advantageous in order to determine presumed penumbral regions and subsequent treatment strategy for acute ischemic stroke (AIS). Our aim was to evaluate interobserver agreement and the clinical utility of intravoxel incoherent motion MR imaging in patients with acute ischemic stroke. We retrospectively studied 29 patients with AIS (17 men, 12 women; mean age, 75.2 [SD, 12.0 ] years; median, 77 years). Each patient underwent intravoxel incoherent motion MR imaging using a 1.5T MR imaging scanner. Diffusion-sensitizing gradients were applied sequentially in the x, y, and z directions with 6 different b-values (0, 50, 100, 150, 200, and 1000 seconds/mm2). From the intravoxel incoherent motion MR imaging data, diffusion coefficient, perfusion fraction, and pseudodiffusion coefficient maps were obtained using a 2-step fitting algorithm based on the Levenberg-Marquardt method. The presence of decreases in the intravoxel incoherent motion perfusion fraction and pseudodiffusion coefficient values compared with the contralateral normal-appearing brain was graded on a 2-point scale by 2 independent neuroradiologists. Interobserver agreement on the rating scale was evaluated using the κ statistic. Clinical characteristics of patients with a nondecreased intravoxel incoherent motion perfusion fraction and/or pseudodiffusion coefficient rated by the 2 observers were also assessed. Interobserver agreement was shown for the intravoxel incoherent motion perfusion fraction (κ = 0.854) and pseudodiffusion coefficient (κ = 0.789) maps, which indicated almost perfect and substantial agreement, respectively. Patients with a nondecreased intravoxel incoherent motion perfusion fraction tended to show recanalization of the occluded intracranial arteries more frequently than patients with a decreased intravoxel incoherent motion perfusion fraction. Intravoxel incoherent motion MR imaging could be performed in < 1 minute in addition to routine DWI. Intravoxel incoherent motion parameters noninvasively provide feasible, qualitative perfusion-related information for assessing patients with acute ischemic stroke.

Covariance shrinkage can assess and improve functional connectomes

Connectomes derived from resting-state functional MRI scans have significantly benefited from the development of dedicated fMRI motion correction and denoising algorithms. But they are based on empirical correlations that can produce unreliable results in high dimension low sample size settings. A family of statistical estimators, the covariance shrinkage methods, could mitigate this issue. Unfortunately, these methods have rarely been used to correct functional connectomes and no extensive experiment has been conducted so far to compare the shrinkage methods available for this task. In this work, we propose to fix this issue by processing a benchmark dataset made of a thousand high-resolution resting-state fMRI scans provided by the Human Connectome Project to compare the ability of five prominent covariance shrinkage methods to produce reliable functional connectomes at different spatial resolutions and scans duration: the pioneer linear covariance shrinkage method introduced by Ledoit and Wolf, the Oracle Approximating Shrinkage, the QuEST method, the NERCOME method, and a recent analytical approximation of the QuEST approach. Our experiments establish that all covariance shrinkage methods significantly improve functional connectomes derived from short fMRI scans. The Oracle Approximating Shrinkage and the QuEST method produced the best results. Lastly, we present shrinkage intensity charts that can be used for designing and analyzing fMRI studies. These charts indicate that sparse connectomes are difficult to estimate from short fMRI scans, and they describe a range of settings where dynamic functional connectivity should not be computed.

CBCT – RADIOLOGICAL ANATOMY OF THE NASAL CAVITYAND THE PARANASAL SINUSES

At present, modern otorhinolaryngology cannot be imagined without such a research method as computed tomography (CT) – a method of non-destructive layer-by-layer study of the object internal structure, which was proposed in 1972 by A. Kormak. The method is based on the measurement and complex computer processing of the difference in X-ray attenuation by different density tissues. Confidently starting in our country in the 80th of the last century, CT is developing, becoming an increasingly perfect method, practically the main X-ray diagnostics method in otorhinolaryngology. Cone-beam computed tomography (CBCT) was first adapted for potential clinical use in 1982 at the Mayo Clinic Biodynamics Research Laboratory (USA). Initially, the technique found application in angiography, in which soft tissues can be brought in to benefit from the possibility of obtaining high temporal and spatial resolution. Available for wide use in the maxillofacial region diagnosis, CBCT became available in 2001 (New Tom QR DVT 9000, Italy). CBCT is a radiological examination method based on the X-rays use by rotating an X-ray tube around a patient to obtain data. It is mainly used in dental practice, but more and more often this technique is introduced into otolaryngological practice. Because modern devices make it possible to obtain all sinuses images at once and characterize them. The biggest advantage of this study is a much lower ionizing radiation dose along with almost the entire range of traditional CT possibilities. The CBCT use is growing in the clinical arena due to its ability to provide 3D information during interventions, its high diagnostic quality (sub-millimeter resolution), and its short scanning times. However, clinical and anatomical evidence pertaining to its efficacy is lacking. The presented article describes the possibilities of using CBCT to characterize the nose and paranasal sinuses anatomical features.&#x0D; The aim. To show the nose and paranasal sinuses X-ray anatomy by retrospective analysis of cone-beam computed tomography images.&#x0D; Methods. To study the topographic and anatomical structures of the facial skull in the norm we analyzed 30 CBCT patients’ images (18 men and 12 women aged from 10 to 62 years) in whom there was no nose and paranasal sinuses pathology, or atypical variants of this area development were determined. The study was conducted using Planmeca ProMax® 3D's innovative Maxillofacial tomograph, which covers the entire sinus area, making it an excellent solution for 3D and 2D visualization of the paranasal sinuses. Descriptions are made using Planmeca Romexis viewer software.&#x0D; Results. With the help of the modern method of radiological examination, particularly CBCT, it is possible to clearly visualize and differentiate the nose and sinuses’ anatomical structure features. As a result of the analysis, we confirmed the fact that the CBCT use is appropriate in patients. This technique allows not only to see but also to measure various indicators (shape, anatomical formations size; contours;) and to compare the nose and paranasal sinuses bone structures. Also, the 3D reconstructions use makes it possible to compare the positions of different anatomical structures of the facial skull. The CBCT effectiveness for assessing the individual anatomy of the nasal cavity and paranasal sinuses has been shown, which can be used both for patients’ preoperative preparation and at the stage of diagnosis and treatment of the nasal cavity and maxillary sinuses various diseases.

Improvement of Quantitative Single-Photon Emission Computed Tomography Image Quality by the New Step-and-Shoot Scan Mode

The step-and-shoot (SS) mode and continuous mode are currently used for single-photon emission computed tomography (SPECT) scan mode, and a new scan mode that combines both modes, step-and-shoot plus continuous (SSC) mode, was developed. It is expected to allow a shorter scan time and lower injected dose because the SSC mode is more sensitive than the SS mode. We confirmed the image quality of this scan mode, including various quantitative correction methods for scatter (SC), attenuation (AC), and resolution recovery (RR) in a phantom study and clinical case study. Image quality was evaluated by the count, contrast-to-noise ratio (CNR), and percent of the coefficient of variation (%CV). Independent of the correction methods, the count, CNR, and %CV of the SSC mode were superior to those of the SS mode. The ACSCRR was the best method, with a maximum increased rate of 66.4% in counts and 57.8% in CNR for the 13-mm sphere and 19.6% in CNR for other sphere sizes. The %CV for the SSC mode was the best for AC and ACRR, which was at 15.1%. With regards to attaining short bone SPECT scan time, the combination of the SSC mode and ACRR or ACSCRR demonstrated the best physical performance.

Applications of cone beam computed tomography in the field of prosthodontics: A review

Cone beam computed tomography (CBCT) is one of the latest radiographic modality available. It is use are enormous in medical and dental field. Among all CBCT is an essential commodity in the field of prosthodontics. The amazing capability of CBCT for providing sub-millimeter resolution in images of high diagnostic quality, with short scanning times (10–70 s) and radiation dosages reportedly up to 15–100 times lower than those of conventional Computed tomography scans are the unique features of CBCT. The aim of this article is to educate the Prosthodontist to CBCT technology, provide an overview of CBCT systems and review the specific application of various CBCT display modes to clinical Prosthodontics practice.

MR-assisted PET respiratory motion correction using deep-learning based short-scan motion fields.

We evaluated the impact of PET respiratory motion correction (MoCo) in a phantom and patients. Moreover, we proposed and examined a PET MoCo approach using motion vector fields (MVFs) from a deep-learning reconstructed short MRI scan. The evaluation of PET MoCo was performed in a respiratory motion phantom study with varying lesion sizes and tumor to background ratios (TBRs) using a static scan as the ground truth. MRI-based MVFs were derived from either 2000 spokes (MoCo2000 , 5-6 min acquisition time) using a Fourier transform reconstruction or 200 spokes (MoCoP2P200 , 30-40 s acquisition time) using a deep-learning Phase2Phase (P2P) reconstruction and then incorporated into PET MoCo reconstruction. For six patients with hepatic lesions, the performance of PET MoCo was evaluated using quantitative metrics (SUVmax , SUVpeak , SUVmean , lesion volume) and a blinded radiological review on lesion conspicuity. MRI-assisted PET MoCo methods provided similar results to static scans across most lesions with varying TBRs in the phantom. Both MoCo2000 and MoCoP2P200 PET images had significantly higher SUVmax , SUVpeak , SUVmean and significantly lower lesion volume than non-motion-corrected (non-MoCo) PET images. There was no statistical difference between MoCo2000 and MoCoP2P200 PET images for SUVmax , SUVpeak , SUVmean or lesion volume. Both radiological reviewers found that MoCo2000 and MoCoP2P200 PET significantly improved lesion conspicuity. An MRI-assisted PET MoCo method was evaluated using the ground truth in a phantom study. In patients with hepatic lesions, PET MoCo images improved quantitative and qualitative metrics based on only 30-40 s of MRI motion modeling data.

KNOWLEDGE AND ATTITUDE TOWARD CONE BEAM COMPUTED TOMOGRAPHY: A QUESTIONNAIRE STUDY AMONG YEMENI DENTAL PRACTITIONERS

Background: Cone beam computed tomography (CBCT) is a marvelous three-dimensional (3D) dental and maxillofacial imaging method industrial in recent years. It is based on a multi-surface resampling process that has distinct advantages such as condensed radiated area size, image resolution, fast scanning time, exclusive maxillofacial imaging patterns and reduced image errors. Objectives: This study aimed to evaluate the knowledge and attitude of a sample of Yemeni dentists toward the use of CBCT. Methods: A total of 98 selected dentists participated in this study. The self-administered questionnaires, consisting of two parts, were distributed: The first is related to the demographic characteristics and the second section is related to the knowledge and attitude of the dental practitioners towards CBCT. The study was conducted in Dhamar city, Yemen. The information was assembled through a pre-prepared questionnaire consisted of 24 structured close-ended questions. Descriptive statistics calculated in terms of frequencies and percentages. A software program (SPSS V25) was used for data analysis. Results: The majority of respondents were 86 general dental practitioners (87.8%), most of whom were working in private dental clinics. More than half of the participants (67.3%) used digital imaging techniques to take radiographs. The most frequent source of knowledge about respondents' digital imaging techniques was the Internet (39%). Awareness of CBCT was higher in dentists, dental specialists, and those who were in an academic position. Lower radiation dose (26%), followed by secure image processing (23%), and short scanning time (21%) were the most common advantages of CBCT reported by the respondents. Conclusion: Study participant responses reflect the importance of CBCT in the dental field. Awareness about CBCT among dentists in Yemen is good and appears to be different among dentists with regard to gender, qualifications and type of work. The study requires that continuing learning courses be held in dental colleges in Yemen including appropriate hands-on CBCT training and integration with other clinical courses to improve the dentist’s basic knowledge and interpretation regarding this technology. Peer Review History: Received: 4 January 2022; Revised: 21 February; Accepted: 3 March, Available online: 15 March 2022 Academic Editor: Dr. Emmanuel O. Olorunsola, Department of Pharmaceutics &amp; Pharmaceutical Technology, University of Uyo, Nigeria, olorunsolaeo@yahoo.com UJPR follows the most transparent and toughest ‘Advanced OPEN peer review’ system. The identity of the authors and, reviewers will be known to each other. This transparent process will help to eradicate any possible malicious/purposeful interference by any person (publishing staff, reviewer, editor, author, etc) during peer review. As a result of this unique system, all reviewers will get their due recognition and respect, once their names are published in the papers. We expect that, by publishing peer review reports with published papers, will be helpful to many authors for drafting their article according to the specifications. Auhors will remove any error of their article and they will improve their article(s) according to the previous reports displayed with published article(s). The main purpose of it is ‘to improve the quality of a candidate manuscript’. Our reviewers check the ‘strength and weakness of a manuscript honestly’. There will increase in the perfection, and transparency. Received file: Reviewer's Comments: Average Peer review marks at initial stage: 6.5/10 Average Peer review marks at publication stage: 7.5/10 Reviewers: Dr. Asia Selman Abdullah, University of Basrah, Iraq, asia_abdullah65@yahoo.com Prof. Dr. Hassan A.H. Al-Shamahy, Sana'a University, Yemen, shmahe@yemen.net.ye Similar Articles: KNOWLEDGE AND PERCEPTION OF MOLAR INCISOR HYPOMINERALIZATION AMONG DENTAL PRACTITIONERS IN SANA’A CITY- YEMEN

Comparative assessment of motion averaged free-breathing or breath-held cardiac magnetic resonance imaging protocols in a porcine myocardial infarction model

Breath-held (BH) cardiac magnetic resonance imaging (CMR) is the gold standard for volumetric quantification. However, large animals for pre-clinical research are unable to voluntarily breath-hold, necessitating general anaesthesia and mechanical ventilation, increasing research costs and affecting cardiovascular physiology. Conducting CMR in lightly sedated, free-breathing (FB) animal subjects is an alternative strategy which can overcome these constraints, however, may result in poorer image quality due to breathing motion artefact. We sought to assess the reproducibility of CMR metrics between FB and BH CMR in a porcine model of ischaemic cardiomyopathy. FB or BH CMR was performed in 38 porcine subjects following percutaneous induction of myocardial infarction. Analysis was performed by two independent, blinded observers according to standard reporting guidelines. Subjective and objective image quality was significantly improved in the BH cohort (image quality score: 3.9/5 vs. 2.4/5; p < 0.0001 and myocardium:blood pool intensity ratio: 2.6–3.3 vs. 1.9–2.3; p < 0.001), along with scan acquisition time (4 min 06 s ± 1 min 55 s vs. 8 min 53 s ± 2 min 39 s; p < 0.000). Intra- and inter-observer reproducibility of volumetric analysis was substantially improved in BH scans (correlation coefficients: 0.94–0.99 vs. 0.76–0.91; coefficients of variation: < 5% in BH and > 5% in FB; Bland–Altman limits of agreement: < 10 in BH and > 10 in FB). Interstudy variation between approaches was used to calculate sample sizes, with BH CMR resulting in greater than 85% reduction in animal numbers required to show clinically significant treatment effects. In summary, BH porcine CMR produces superior image quality, shorter scan acquisition, greater reproducibility, and requires smaller sample sizes for pre-clinical trials as compared to FB acquisition.

Performance evaluation of a micro-CT system for laboratory animal imaging with iterative reconstruction capabilities.

In recent years, there has been a rapid proliferation in micro-computed tomography (micro-CT) systems becoming more available for routine preclinical research, with applications in many areas, including bone, lung, cancer, and cardiac imaging. Micro-CT provides the means to non-invasively acquire detailed anatomical information, but high-resolution imaging comes at the cost of longer scan times and higher doses, which is not desirable given the potential risks related to x-ray radiation. To achieve dose reduction and higher throughputs without compromising image quality, fewer projections can be acquired. This is where iterative reconstruction methods can have the potential to reduce noise since these algorithms can better handle sparse projection data, compared to filtered backprojection PURPOSE: We evaluate the performance characteristics of a compact benchtop micro-CT scanner that provides iterative reconstruction capabilities with GPU-based acceleration. We thereby investigate the potential benefit of iterative reconstruction for dose reduction. Based on a series of phantom experiments, the benchtop micro-CT system was characterized in terms of image uniformity, noise, low contrast detectability, linearity, and spatial resolution. Whole-body images of a plasticized ex vivo mouse phantom were also acquired. Different acquisition protocols (general-purpose versus high-resolution, including low dose scans) and different reconstruction strategies (analytic versus iterative algorithms: FDK, ISRA, ISRA-TV) were compared. Signal uniformity was maintained across the radial and axial field-of-view (no cupping effect) with an average difference in Hounsfield units (HU) between peripheral and central regions below 50. For low contrast detectability, regions with at least ∆HU of 40 to surrounding material could be discriminated (for rods of 2.5mm diameter). A high linear correlation (R2 =0.997) was found between measured CT values and iodine concentrations (0-40mg/ml). Modulation transfer function (MTF) calculations on a wire phantom evaluated a resolution of 10.2 lp/mm at 10% MTF that was consistent with the 8.3% MTF measured on the 50µm bars (10 lp/mm) of a bar-pattern phantom. Noteworthy changes in signal-to-noise and contrast-to-noise values were found for different acquisition and reconstruction protocols. Our results further showed the potential of iterative reconstruction to deliver images with less noise and artefacts. In summary, the micro-CT system that was evaluated in the present work was shown to provide a good combination of performance characteristics between image uniformity, low contrast detectability, and resolution in short scan times. With the iterative reconstruction capabilities of this micro-CT system in mind (ISRA and ISRA-TV), the adoption of such algorithms by GPU-based acceleration enables the integration of noise reduction methods which here demonstrated potential for high-quality imaging at reduced doses.

APPLICATION OF THE CONE BEAM COMPUTED TOMOGRAPHY (CBCT) MODALITY WITH WEIGHT BEARING TECHNIQUE TO IDENTIFY OSTEOARTHRITIS (OA) IN THE KNEE JOINT

ABSTRACTBackground : Osteoarthritis (OA) is a degenerative joint disease that causes inflammation of the cartilage due to the load that is often received by the joints. The knee joint is a part that is often affected by OA. Radiographic and CT examinations can be used to check for OA of the knee. Radiographic examination has the advantage of optimally displaying OA because the examination is carried out under weight bearing conditions, and CT is superior in displaying anatomical details due to cross sectional and 3D reconstruction. Technological developments present Cone Beam CT (CBCT) weight bearings that combine the advantages of radiographic and CT examinations. The purpose of this study is to determine the role and benefits of CBCT weight bearing on knee joint image information in cases of OA.Method : This type of research is literature review research with a narrative review approach. The databases used in the review articles include Science Direct, ProQuest, PubMed, DOAJ, Google Scholar, Wiley Online Library, ISI Web of Knowledge, and the Oxford Journal. The articles that have been obtained will be processed in tabulated form for later extraction.Result : The results of this study indicate that weight bearing is able to assess degeneration causing internal rotation in the range of +/- 2.8-3.1o, lateral patellar shift up to +/- 0.4 mm, joint space width (JSW) up to +/- 0.5 mm, meniscal extrusion (ME) up to +/- 10.2 mm. Conclusion : CBCT is used to obtain volumetric and cross sectional 3D knee images, in order to obtain images with high spatial resolution with low doses, detailed bone structure images, short scan times, visualization of narrowing and progression of OA in JSW clearly, visualization of OA in the menisci, as well as visualizing the complexity of the joint and soft tissue images so that OA is easily identified.

Efficient non-contrast enhanced 3D Cartesian cardiovascular magnetic resonance angiography of the thoracic aorta in 3\xa0min

BackgroundThe application of cardiovascular magnetic resonance angiography (CMRA) for the assessment of thoracic aortic disease is often associated with prolonged and unpredictable acquisition times and residual motion artefacts. To overcome these limitations, we have integrated undersampled acquisition with image-based navigators and inline non-rigid motion correction to enable a free-breathing, contrast-free Cartesian CMRA framework for the visualization of the thoracic aorta in a short and predictable scan of 3 min.Methods35 patients with thoracic aortic disease (36 ± 13y, 14 female) were prospectively enrolled in this single-center study. The proposed 3D T2-prepared balanced steady state free precession (bSSFP) sequence with image-based navigator (iNAV) was compared to the clinical 3D T2-prepared bSSFP with diaphragmatic-navigator gating (dNAV), in terms of image acquisition time. Three cardiologists blinded to iNAV vs. dNAV acquisition, recorded image quality scores across four aortic segments and their overall diagnostic confidence. Contrast ratio (CR) and relative standard deviation (RSD) of signal intensity (SI) in the corresponding segments were estimated. Co-axial aortic dimensions in six landmarks were measured by two readers to evaluate the agreement between the two methods, along with inter-observer and intra-observer agreement. Kolmogorov–Smirnov test, Mann–Whitney U (MWU), Bland–Altman analysis (BAA), intraclass correlation coefficient (ICC) were used for statistical analysis.ResultsThe scan time for the iNAV-based approach was significantly shorter (3.1 ± 0.5 min vs. 12.0 ± 3.0 min for dNAV, P = 0.005). Reconstruction was performed inline in 3.0 ± 0.3 min. Diagnostic confidence was similar for the proposed iNAV versus dNAV for all three reviewers (Reviewer 1: 3.9 ± 0.3 vs. 3.8 ± 0.4, P = 0.7; Reviewer 2: 4.0 ± 0.2 vs. 3.9 ± 0.3, P = 0.4; Reviewer 3: 3.8 ± 0.4 vs. 3.7 ± 0.6, P = 0.3). The proposed method yielded higher image quality scores in terms of artefacts from respiratory motion, and non-diagnostic images due to signal inhomogeneity were observed less frequently. While the dNAV approach outperformed the iNAV method in the CR assessment, the iNAV sequence showed improved signal homogeneity along the entire thoracic aorta [RSD SI 5.1 (4.4, 6.5) vs. 6.5 (4.6, 8.6), P = 0.002]. BAA showed a mean difference of < 0.05 cm across the 6 landmarks between the two datasets. ICC showed excellent inter- and intra-observer reproducibility.ConclusionsThoracic aortic iNAV-based CMRA with fast acquisition (~ 3 min) and inline reconstruction (3 min) is proposed, resulting in high diagnostic confidence and reproducible aortic measurements.

Clinical Application of MPRAGE Wave Controlled Aliasing in Parallel Imaging (Wave-CAIPI): A Comparative Study with MPRAGE GRAPPA.

To compare reliability and elucidate clinical application of magnetization-prepared rapid gradient-echo (MPRAGE) with 9-fold acceleration by using wave-controlled aliasing in parallel imaging (Wave-CAIPI 3 × 3) in comparison to conventional MPRAGE accelerated by using generalized autocalibrating partially parallel acquisition (GRAPPA) 2 × 1. A total of 26 healthy volunteers and 33 patients were included in this study. Subjects were scanned with two MPRAGEs, GRAPPA 2 × 1 and Wave-CAIPI 3 × 3 acquired in 5 min 21 s and 1 min 42 s, respectively, on a 3T MR scanner. Healthy volunteers underwent additional two MPRAGEs (CAIPI 3 × 3 and GRAPPA 3 × 3). The image quality of the four MPRAGEs was visually evaluated with a 5-point scale in healthy volunteers, and the SNR of four MPRAGEs was also calculated by measuring the phantom 10 times with each MPRAGE. Based on the results of the visual evaluation, voxel-based morphometry (VBM) analyses, including subfield analysis, were performed only for GRAPPA 2 × 1 and Wave-CAIPI 3 × 3. Correlation of segmentation results between GRAPPA 2 × 1 and Wave-CAIPI 3 × 3 was assessed. In visual evaluations, scores for MPRAGE GRAPPA 2 × 1 (mean rank: 4.00) were significantly better than those for Wave-CAIPI 3 × 3 (mean rank: 3.00), CAIPI 3 × 3 (mean rank: 1.83), and GRAPPA 3 × 3 (mean rank: 1.17), and scores for Wave-CAIPI 3×3 were significantly better than those for CAIPI 3 × 3 and GRAPPA 3 × 3. Image noise was evident at the center for additional MPRAGE CAIPI 3 × 3 and GRAPPA 3 × 3. The correlation of segmentation results between GRAPPA 2 × 1 and Wave-CAIPI 3 × 3 was higher than 0.85 in all VOIs except globus pallidus. Subfield analysis of hippocampus also showed a high correlation between GRAPPA 2 × 1 and Wave-CAIPI 3 × 3. MPRAGE Wave-CAIPI 3 × 3 shows relatively better contrast, despite of its short scan time of 1 min 42 s. The volumes derived from automated segmentation of MPRAGE Wave-CAIPI are considered to be reliable measures.

203 Ultrasound Identification of the Cricothyroid Membrane for Emergency Front of Neck Access

The difficult airway society states that emergency front of neck access skills should be recapped every 6 months amongst those practitioners expected to perform the skill. Furthermore, the national audit states that, of the 25 emergency cricothyroidotomy cases, 9 failed. These were largely due to incorrect identification of the midline and tube misplacement. There is a convincing argument for training practitioners in ultrasound identification of the cricothyroid membrane, mitigating the risks of incorrect midline identification and blood vessel damage Our aim was two-fold: introduce and embed the skill of ultrasound identification of the cricothyroid membrane for use in emergency front of neck access and encourage regular recap of these skills through a training package of blended learning, consisting of videos, ‘tea trolley’ style theatre training and a more formal simulation-based course that focuses on the ultrasound and front of neck access skill and human factors as we know this is a key factor in the success or failure of this scenario.A pilot course was rolled out amongst anaesthetic trainees to assess relative comfort with performing emergency front of neck access. The course consisted of a short lecture on the background and anatomy, teaching of the ultrasound skill using live subjects, practising of ultrasound-guided front of neck access on animal necks and finally a simulation with debrief surrounding implementation of the skill itself and human factors. This course is now being rolled out regionally and aims to teach all trainees in the region. We encourage trainees to generate their own informal logbook of ultrasound cases, whereby they consent patients to undergo a short ultrasound scan in the anaesthetic room prior to intubation, have their neck marked and then are rescanned after intubation to confirm correct identification. This should be done with ‘normal’ airways, not just those expected to be difficult, as this practice embeds the skill. Our ‘tea trolley’ style teaching is yet to be commenced but will involve ad hoc teaching within the theatre suite including the multi-disciplinary team who would be involved in such an event – the anaesthetist, operating department practitioner and theatre team. Finally, we are generating a video bank, which can be accessed in users’ own time to recap and review the process and troubleshooting of ultrasound identification of the cricothyroid membrane and ensuing cricothyroidotomy.An improvement was reported in trainees’ comfort levels to perform ultrasound-guided cricothyroidotomy and all trainees felt that this was a worthwhile skill to embed into their practice. These improvements were tested via a pre- and post-course questionnaire. The same we hope will be true for the tea trolley training and we aim to address the human factors involved during these sessions too.The aspiration is that ultimately ultrasound identification of the cricothyroid membrane for emergency front of neck access will at the very least become a skill that all trainees are formally taught and encouraged to practice and at the most will become the new standard for plan D airway access in the difficult airway society guidelines.

Diffusion-Weighted Imaging of the Macaque Brain Using Diffusion-Prepared Turbo Spin Echo in MRI

Magnetic resonance imaging (MRI) integrates a static magnetic field, a time-varying gradient magnetic field at kHz and a radio-frequency (RF) magnetic field for non-invasive and real-time imaging; meanwhile, diffusion MRI (dMRI) pushes a further and closer dimension to the scale of neural fibers through sensitizing the gradient field to recognize water molecular displacement over distances of 1~20 μm along fibers. Contemporary dMRI approaches face challenges of magnetic field inhomogeneity as well as sequence-associated distortion and signal loss, the common remedies of which are repeated scans and post-reconstruction algorithms. In this study, over an anesthetized macaque with a customized head coil on 3 T MRI, we have proposed and implemented a monopolar diffusion-prepared module for turbo spin echo sequence (DP-TSE) as an alternative to achieve distortion-free, high-resolution diffusion imaging with improved SNR. The results showed high image quality and SNR efficiency as compared with conventional dMRI methods at millimeter level, allowing us to pursue submillimeter-scale dMRI over non-human primates (NHPs) in a relatively short scan time and without repetitions or post-processing, which could merit and advance our understanding of the structure and organizations of the primate’s brain.