Clinical Multislice Computed Tomography Research Articles

Cone-Beam CT Compared to Multi-Slice CT for the Diagnostic Analysis of Conductive Hearing Loss: A Feasibility Study

Multislice computed tomography (MSCT) is commonly used as a diagnostic tool for patients with a conductive hearing loss. Recent studies indicate that cone-beam computed tomography (CBCT) may be used as a low-radiation dose alternative for temporal bone imaging. This study compares image quality and radiation dose between CBCT and MSCT when assessing anatomical landmarks related to conductive hearing loss. Five human cadaver heads (10 ears) were imaged on the NewTom 5G CBCT and the Discovery CT750 HD MSCT. Visibility of 16 anatomical landmarks of the middle and inner ear was assessed by two observers on a 4-point Likert scale. Furthermore, effective radiation dose was compared, and contrast-to-noise ratio and spatial resolution were measured with a phantom head. Image quality of CBCT was assessed as superior to MSCT. Effective radiation dose of the high-resolution CBCT protocol was 30.5% of the clinical MSCT dose. High-resolution CBCT was reported as having a higher spatial resolution and superior contrast-to-noise perception in comparison with MSCT. High-resolution CBCT was evaluated as superior to MSCT in the assessment of structures related to conductive hearing loss. Furthermore, CBCT imaging resulted in a considerably lower effective radiation dose.

Quantitative CT-based bone strength parameters for the prediction of novel spinal implant stability using resonance frequency analysis: a cadaveric study involving experimental micro-CT and clinical multislice CT

BackgroundTo predict conventional test forces (peak torque and pull-out force) and a new test force (implant stability quotient [ISQ] value of a spinal pedicle screw) from computed tomography (CT) parameters, including micro-architectural parameters, using high-resolution micro-CT and clinical multislice CT (MSCT) in human cadaveric vertebrae.MethodsMicro-CT scans before/after screw insertion (n = 68) and MSCT scans before screw insertion (n = 58) of human cadaveric vertebrae were assessed for conventional test forces and ISQ value. Three-dimensional volume position adjustment between pre-insertion micro-CT and MSCT scans and post-insertion scans (micro-CT) was performed to extract the volume of the cancellous bone surrounding the pedicle screw. The following volume bone mineral density and micro-architectural parameters were calculated: bone volume fraction, bone surface density (bone surface/total volume (BS/TV)), trabecular thickness, trabecular separation, trabecular number, structure model index, and number of nodes (branch points) of the cancellous bone network/total volume (NNd/TV) using Spearman’s rank correlation coefficient with Bonferroni correction.ResultsConventional test forces showed the strongest correlation with BS/TV: peak torque, ρ = 0.811, p = 4.96 × 10−17(micro-CT) and ρ = 0.730, p = 7.87 × 10−11 (MSCT); pull-out force, ρ = 0.730, p = 1.64 × 10−12 (micro-CT) and ρ = 0.693, p = 1.64 × 10−9 (MSCT). ISQ value showed the strongest correlation with NNd/TV: ρ = 0.607, p = 4.01 × 10−8 (micro-CT) and ρ = 0.515, p = 3.52 × 10−5 (MSCT).ConclusionsTest forces, including the ISQ value, can be predicted using micro-CT and MSCT parameters. This is useful for establishing a preoperative fixation strength evaluation system.

Validation of the İşcan method in clinical MSCT scans specific to an Australian population.

The transposition of traditional biological profiling methods to virtual skeletal reconstructions represents a relatively novel practice that is proving to be versatile in a variety of forensic contexts. Widespread acknowledgement of the disadvantages associated with archaeological and/or other non-contemporary skeletal collections has prompted an increase in the use of medical imaging modalities for the purposes of formulating population-specific reference standards used to estimate characteristics such as chronological age. The primary aim of the present study is to statistically evaluate the reproducibility of assessment and thereafter develop age estimation standards based on the morphoscopic evaluation of the fourth right sternal rib following the phase ageing method developed as reported by İşcan et al. (J Forensic Sci 29:1094-1104, 1984, J Forensic Sci 30:853-863, 1985) in clinical multi-slice computed tomography (MSCT) scans. A total of 335 MSCT scans representing Western Australian individuals between 10 and 80years of age (179 male and 156 female) were retrospectively reconstructed and analysed in OsiriX following the İşcan et al. sex-specific standards (J Forensic Sci 29:1094-1104, 1984, J Forensic Sci 30:853-863, 1985) for the fourth right rib. Regression and transition analyses are employed to generate standards for the estimation of chronological age and modelling of thoracic senescence, respectively. The method was also applied to right ribs three and five to evaluate intercostal variance in age-related metamorphosis. Intra- and inter-observer accordance is 'substantial' (K = 0.76) and 'almost perfect' (K = 0.825), respectively. Intercostal variances between ribs three to five were observed in the male sample only. Multiple regression using phase scores from all three ribs produced models with the highest predictive accuracy (± 10.04years for males and ± 9.81years for females). The transition analyses demonstrate comparable levels of age-related morphological change across ribs and male and female samples. This study presents a novel set of reference standards for a contemporary Australian population and further demonstrates the utility of virtual analysis in forensic anthropology.

Cone-beam CT versus multi-slice CT systems for postoperative imaging of cochlear implantation--a phantom study on image quality and radiation exposure using human temporal bones.

Image quality of low-dose multi-slice computed tomography (MSCT) after cochlear implantation is comparable to that of cone-beam computed tomography (CBCT). CBCT has been described as a low-dose alternative with superior image quality to MSCT for postoperative cochlear implant (CI) imaging, but to our knowledge, no dose-matched comparisons of image quality have been published. Five human cochleae were implanted with CI electrodes and scanned on two CBCT and two MSCT systems. Four independent observers rated aspects of image quality on a five-point scale. CBCT scans were compared to clinical and dose-matched MSCT scans. Declining-dose MSCT protocols were compared to the clinical protocol. CT phantoms were used to determine effective dose and resolution for each acquisition protocol. Effective dose of the CBCT protocols was 6 to 16% of the clinical MSCT dose. Visibility of cochlear inner and outer walls and overall image quality were positively correlated with radiation dose on MSCT and image quality was better with clinical MSCT than with CBCT protocols. In other comparisons, differences between systems were found, but a distinction between CBCT and MSCT could not be made. CBCT and dose-matched MSCT are both suitable for postoperative CI imaging. Selecting a CT system and radiation dose depends on which cochlear structures need to be visualized.

Internal or in-scan validation: a method to assess CBCT and MSCT gray scales using a human cadaver.

This study aimed to explore whether cone beam computed tomography (CBCT) and multislice computed tomography (MSCT) can be used to quantify tissue density and to determine if the Hounsfield unit scale is applicable. A clinical MSCT scanner and effective energy adjusted photon beam attenuation references were used to compare the gray scale of CBCT images of the mandible region. A phantom was scanned using axial cadaver slices and 4 different homogeneous reference objects. The consistency of the references' gray values and 12 linear profile lines from both scanner data sets were compared. The gray values of the 2 scans showed strong correlation with quantified position-dependent differences as an outcome of the validation process. The introduced internal, in-scan validation is able to estimate and has a potential to compensate for the differences between MSCT and CBCT protocols. This validation serves as a guide in situations where the users can expect deviations.

Organ point dose measurements in clinical multi slice computed tomography (MSCT) examinations with the MOSkin™ radiation dosimeter

This study reports on the application of the MO Skin ™ dosimeter in MSCT imaging for the real-time measurement of absorbed organ point doses in a tissue-equivalent female anthropomorphic phantom. MO Skin ™ dosimeters were placed within the phantom to measure absorbed point organ doses for 2 commonly applied clinical scan protocols, namely the renal calculus scan and the pulmonary embolus scan. Measured organ doses in the imaged field of view were found to be in the dose range 4.7–9.5 mGy and 16.2–27.4 mGy for the renal calculus scan and pulmonary scan protocols respectively. For the derivation of effective dose, using the more recent ICRP 103 tissue weighting factors ( w T ) compared to that of the ICRP 60 w T resulted in a difference in the derived effective dose by up to 0.8 mSv (−20%) in the renal calculus protocol and up to 1.8 mSv (18%) in the pulmonary embolus protocol. This difference is attributed to the reduced radiosensitivity of the gonads and the increased radiosensitivity of breast tissue in the latest ICRP 103 assigned w T . The results of this study show that the MO Skin ™ dosimeter is a useful real-time tool for the direct assessment of organ doses in clinical MSCT examinations. • The MO Skin ™ dosimeter was used to measure CT organ point doses. • Effective doses varied depending on ICRP 60 or 103 w T factors used in the derivation. • The results show that the MO Skin ™ dosimeter is a useful real-time clinical dosimetry tool.

Improving understanding of early behavioral indicators of lumbosacral disease in working dogs using 3D visualization of skeletal movements during working tasks: Feasibility study

Abstract An improved understanding of the early behavioral indicators of lumbosacral disease in working dogs may allow earlier interventions and help reduce premature retirement because of disability. However, recognition of early behavioral indicators can be challenging in stoic, high-drive working dogs because they often mask clinical signs. The purpose of this feasibility study was to develop a technique for visualizing canine skeletal movements during working tasks and to describe veterinary clinical specialist opinions on the utility of the visualization technique. Three detection-trained police dogs with a recent history of working task deficits and suspected lumbosacral disease were recruited for the study. Conventional and motion capture video recordings were acquired as dogs performed walking and search high working tasks. Whole-body computed tomography (CT) scans were acquired using clinical multislice CT scanners. Image data from motion capture recordings and whole-body CT scans were analyzed and merged. Three-dimensional (3D) computer animation video clips of skeletal movements were created for each dog and each task, using multiple viewing angle perspectives. Interactive meetings with veterinary clinical specialist reviewers were used to refine point placements for the final renderings. Veterinary clinical specialists reviewed final 3D animation movie clips and recorded their opinions on the utility for the visualization technique. Veterinary clinical specialists reported that the computer animations helped them recognize behavioral characteristics that they had not initially noticed in physical examinations. Potential applications for this visualization technique include creating educational training aids for veterinary students, owners, and handlers; assisting veterinarians in planning rehabilitative treatments; and assisting researchers in developing computer models for biomechanical analyses. Future controlled prospective studies are needed in a large number of normal and affected working dogs to improve accuracy of the visualization technique and test the effect of the technique on observer performance.

Detection and characterization of traumatic scalp injuries for forensic evaluation using computed tomography

The purpose of this prospective study was to evaluate the rate of detection and correct classification of traumatic soft tissue injuries of the head using clinical multislice computed tomography (MSCT) compared with an external forensic examination. Thirty-one patients with soft tissue injuries after head trauma and clinically indicated cerebral MSCT scan underwent an external forensic examination with documentation of the morphological appearance and the exact localization of scalp and facial injuries. MSCT data were evaluated by a radiologist blinded to the results of the external examination using axial images as well as multiplanar reconstruction tools. The results of the radiological and forensic report were compared and analyzed. The main finding was that clinical MSCT data of the head detected 55 % of all external lesions and diagnosed the correct morphological type of lesion in 30 %. All lacerations and 44 % of the hematomas were correctly identified in the radiological report, whereas the diagnosis of swellings and abrasions was difficult. MSCT showed a high specificity for all types of soft tissue lesions. Additionally, a substantial number of internal lesions such as fractures or intracerebral bleedings were revealed which were not detected in the external examination. The results demonstrate that the forensic-radiologic evaluation of clinical MSCT data has a good diagnostic performance and is a valuable method to retrospectively supplement external forensic examination in living crime victims. It also might-to a certain extent-be used as the only source in cases where no forensic external examination has taken place within due time.

Comparison between effective radiation dose of CBCT and MSCT scanners for dentomaxillofacial applications

Objectives To compare the effective dose levels of cone beam computed tomography (CBCT) for maxillofacial applications with those of multi-slice computed tomography (MSCT). Study design The effective doses of 3 CBCT scanners were estimated (Accuitomo 3D ®, i–CAT ®, and NewTom 3G ®) and compared to the dose levels for corresponding image acquisition protocols for 3 MSCT scanners (Somatom VolumeZoom 4 ®, Somatom Sensation 16 ® and M×8000 IDT ®). The effective dose was calculated using thermoluminescent dosimeters (TLDs), placed in a Rando ® Alderson phantom, and expressed according to the ICRP 103 (2007) guidelines (including a separate tissue weighting factor for the salivary glands, as opposed to former ICRP guidelines). Results Effective dose values ranged from 13 to 82 μSv for CBCT and from 474 to 1160 μSv for MSCT. CBCT dose levels were the lowest for the Accuitomo 3D ®, and highest for the i-CAT ®. Conclusions Dose levels for CBCT imaging remained far below those of clinical MSCT protocols, even when a mandibular protocol was applied for the latter, resulting in a smaller field of view compared to various CBCT protocols. Considering this wide dose span, it is of outmost importance to justify the selection of each of the aforementioned techniques, and to optimise the radiation dose while achieving a sufficient image quality. When comparing these results to previous dosimetric studies, a conversion needs to be made using the latest ICRP recommendations.

Spiral interpolation algorithm for multislice spiral CT--part I: theory.

This paper presents the adaptive axial interpolator (AAI), a novel spiral interpolation approach for multislice spiral computed tomography (CT) implemented in a clinical multislice CT scanner, the SOMATOM Volume Zoom (Siemens Medical Systems, Forchheim, Germany). The method works on parallel-beam data generated from the acquired fan-beam data by azimuthal rebinning. Spiral interpolation is performed by distance-dependent weighting; i.e., for each ray, its distance to the image plane is evaluated and serves as an argument to a freely selectable weighting function, resulting in a weight factor. A normalization step is applied to the weight factors to ensure that the sum of all corresponding weights (i.e., the weights applied to rays that contribute to the same ray in the interpolated sinogram) is 1. By selection of appropriate weighting functions and suitable adjustment of the tube current, it is possible to keep the slice sensitivity profiles (SSP) as well as the pixel noise constant for all pitch values in the relevant range. Also, a large range of slice-thickness can be reconstructed from a given collimation. The method is, thus, very versatile. Further advantages are that it uses the entire applied dose for imaging and allows for efficient implementation using a table lookup approach.