scholarly journals Estimation of contrast-to-noise ratio in CT and CBCT images with varying scan settings in presence of different implant materials

2019 ◽  
Vol 48 (8) ◽  
pp. 20190139
Author(s):  
Emine Şebnem Kursun-Cakmak ◽  
Husniye Demirturk Kocasarac ◽  
Seval Bayrak ◽  
Gülbahar Ustaoğlu ◽  
Marcel Noujeim
Keyword(s):  
Image Quality ◽  
Imaging Modality ◽  
Cone Beam Ct ◽  
Medical Systems ◽  
Plastic Container ◽  
Implant Materials ◽  
Different Types ◽  
Noise Ratio ◽  
Titanium Grade ◽  
Imagej Software

Objectives: To assess the contrast-to-noise ratio (CNR) of four different types of dental implant materials in CT and cone beam CT (CBCT) images with varying scan settings. Methods: Four different types of implants: zirconium (Zr), titanium (Ti) Grade 4 and 5 and titanium–zirconium (Ti–ZrO2) alloy were placed in a 3% gelatin phantom in a cylindrical plastic container and scanned with two different CT machines (GE Medical systems and Toshiba Medical Systems) and one CBCT machine (I-CAT, Imaging Sciences International) with different voxel sizes of 0.2, 0.25, 0.3 and 0.4 mm. Images were analyzed using ImageJ software with the purpose of estimating the CNR. Results: The CNR obtained from images acquired with CT was lower than the CBCT with all voxel sizes tested. 0.3 and 0.4 mm voxel sizes exhibited the highest CNR (p < 0.05) that gives the best image quality. Among the implant materials tested, titanium Grade 5 has the highest levels of CNR while Zirconium has the lowest (p < 0.05). Conclusions: The optimum protocol for radiographic follow-up in areas near implants on the I-CAT is low-resolution settings (0.3 and 0.4 mm voxel sizes) which gave the highest CNR thus image quality. In presence of Zr implants, an alternative imaging modality (i.e., MRI) may be considered to avoid low-quality images.

scholarly journals Relationship between CNR and visibility of anatomical structures of cone-beam computed tomography images under different exposure parameters

2020 ◽  
Vol 49 (5) ◽  
pp. 20190336
Author(s):  
Miss Fei Wang ◽  
Xiaoyan Xie ◽  
Gang Li ◽  
Zuyan Zhang
Keyword(s):  
Image Quality ◽  
Change Point ◽  
Cone Beam Ct ◽  
Cone Beam ◽  
Physical Factors ◽  
Anatomical Structures ◽  
Subjective Image Quality ◽  
Computed Tomography Images ◽  
Tissue Equivalent ◽  
Imagej Software

Objectives: The purpose of this study was to investigate the image quality of cone beam CT (CBCT) under different exposure parameters and the relationship between contrast-to-noise and visibility of eight anatomical structures. Methods: CBCT images for the evaluation of subjective image quality were acquired on an anthropopathic phantom containing a human skeleton embedded in soft tissue equivalent materials using 25 exposure protocols. Visibility of eight anatomical structures was evaluated by five independent observers. Using the SEDENTEXCT IQ Image Quality phantom, the contrast-to-noise ratio (CNR) was calculated by ImageJ software. Results: A reduction on the visibility of anatomical structures was seen under lower exposure parameters. However, for 84% of the protocols, visibility of anatomical structures remained acceptable even under some lower parameter settings. As CNR increased, the visibility of anatomical structures also increased correspondingly. A change point could be found in the CNR interval 29.42–36.51 after which the visibility of anatomical structures no longer increases with the increase of CNR. Conclusions: Although CNR decrease under a lower exposure parameter, the image quality often remained acceptable at exposure levels below the manufacture’s recommended settings. It is possible to standardize subjective image quality by physical factors. Currently, it is not possible to predetermine a change point CNR value due to different CBCT machine and variation of diagnostic tasks.

scholarly journals Salvage of Suboptimal Enhancement of Pulmonary Artery in Pulmonary CT Angiography Studies: Rapid kVp Switch Dual Energy CT Experience

2020 ◽  
Vol 17 (2) ◽  
Author(s):  
Selen Bayraktaroglu ◽  
Akın Cinkooglu ◽  
Naim Ceylan ◽  
Recep Savas
Keyword(s):  
Pulmonary Embolism ◽  
Image Quality ◽  
Pulmonary Artery ◽  
Imaging Modality ◽  
Main Pulmonary Artery ◽  
Pulmonary Arteries ◽  
Dual Energy ◽  
Dual Energy Ct ◽  
Average Increase ◽  
Noise Ratio

Background: Multidetector computed tomography (MDCT) angiography is considered as the gold standard imaging modality in the evaluation of acute pulmonary embolism. Optimum vascular enhancement is critical for MDCT studies. The suboptimal opacification in pulmonary artery could be salvaged using low-energy virtual monoenergetic images (VMI) at rapid kVp switch dual energy CT. Objectives: To explore the potential improvement in pulmonary artery opacification and to assess the change in image quality parameters in VMI using fast switch kVp dual energy CT. Patients and Methods: The CT images of 877 patients who were referred with a preliminary diagnosis of pulmonary embolism were reviewed. Sixty patients with suboptimal enhancement (< 200 Hounsfeld Unit [HU]) were involved. Standard images (140 kVp) and VMI from 40 to 120 keV were generated. Attenuation, noise, signal to noise ratio (SNR) and contrast to noise ratio (CNR) were measured in the pulmonary artery. Using VMIs, the best image was determined as the image with the main pulmonary artery opacification greater than 200 HU and image quality ≥ 3. Fifty six studies that met these criteria were considered as salvaged. At this best energy level, quantitative parameters were compared with standard images. Results: The mean attenuation of pulmonary arteries was 169.80 HU in standard images in patients with suboptimal enhancement. The attenuations of VMIs at 40, 45, 50, 55, 60, 65, and 70 keV were significantly higher than standard images (P < 0.001). Similar findings were observed with SNR and CNR. In the salvaged patients, the average increase in mean pulmonary artery attenuation was 62% (from 172.61 ± 23.4 to 280.55 ± 40.7), the average increase in SNR was 38% (from 12.1 ± 5.3 to 16.7 ± 7.1) and the average increase in CNR was 48% (9.2 ± 4.3 to 13.7 ± 6) (P < 0.001). Conclusions: Low keV VMI reconstructions significantly increase pulmonary artery attenuation, CNR and SNR compared to standard image reconstructions. Suboptimal CT studies could be salvaged using low keV VMIs.

Flat Panel Cone Beam Computed Tomography of the Sinuses

2008 ◽  
Vol 139 (2_suppl) ◽  
pp. P77-P78
Author(s):  
Richard A Zoumalan ◽  
Kathryn Shouyee Yung ◽  
Edwin Wang ◽  
Richard A Lebowitz ◽  
Joseph B Jacobs
Keyword(s):  
Image Quality ◽  
Ct Scan ◽  
Low Dose ◽  
Multidetector Ct ◽  
Imaging Modality ◽  
Cone Beam Ct ◽  
Image Noise ◽  
Cone Beam ◽  
High Dose ◽  
Flat Panel

Objective Flat panel cone beam CT is a relatively new technology that improves upon traditional multidetector CT scanners by generating images with greater spatial resolution at lower radiation doses. 1) Learn whether flat panel cone beam CT evaluation is an effective imaging modality for the sinuses. 2) Learn which doses of radiation provide quality evaluation of the sinuses while exposing the patient to the least amount of radiation. Methods In 2007, a panel consisting of neuroradiologists and otolaryngologists blindly reviewed images from flat panel sinus CTs (Xoran MiniCAT) of 11 live human subjects, each irradiated at all 3 different techniques (denoted as: low dose mAs=9.27, medium dose mAs = 18.41, high dose mAs=36.7) and rated the image quality of a pre-designated list of sinus anatomic structures. Techniques were compared in a pairwise manner using a Wilcoxon matched-pairs signed ranks test. Results Compared to the low dose technique CT scan, the high dose CT scan technique had significantly better image quality (P=.0029) and image noise (P=.0049). Similarly, the medium dose CT scan technique had significantly better image quality (P=.0020) and image noise (P = .0010) compared to the low dose technique. No difference in image quality and image noise existed between the medium and high dose techniques. No difference in visualization of 13 specific anatomic structures existed between any of the dose techniques. Conclusions Lower dose CT techniques achieved by flat panel cone beam CT may be an effective and safe alternative to traditional multidetector CT scanners. This imaging modality may help patients avoid unnecessary radiation to sensitive organs.

scholarly journals An Image Quality Comparison Study Between Homemade and Commercial Dental Cone-beam CT Systems

2021 ◽  
Author(s):  
Trang Thi Ngoc Tran ◽  
David Shih-Chun Jin ◽  
Kun-Long Shih ◽  
Ming-Lun Hsu ◽  
Jyh-Cheng Chen
Keyword(s):  
Image Quality ◽  
Spatial Resolution ◽  
Cone Beam Ct ◽  
Calcium Hydroxyapatite ◽  
Cone Beam ◽  
Micro Ct ◽  
Mineral Density ◽  
Image Intensity ◽  
System A ◽  
Noise Ratio

Abstract Purpose: Cone-beam computed tomography (CBCT) has been widely applied in dental and maxillofacial imaging. Several dental CBCT systems have been recently developed in order to improve the performance. This study aimed to evaluate the image quality of our prototype (YMU-DENT-P001) and compare with another commercial CBCT system made in Taipei, Taiwan (system A). Methods: The Micro-CT-Contrast Scale, Micro-CT Water and Micro-CT HA phantoms were utilized to evaluate the contrast to noise ratio (CNR), signal to noise ratio (SNR), uniformity, distortion, and the linear relation between image intensity and calcium hydroxyapatite concentrations. Another customized thin-wire phantom was used to evaluate the FWHM spatial resolution. These phantoms were scanned by the two CBCT systems using the same exposure protocol. Acquired data were evaluated using the image analysis platform designed by our lab, which followed ISO standard. Results: The SNR of our prototype YMU-DENT-P001 is nearly five times higher (prototype: 159.85 ± 3.88; A: 35.42 ± 0.61; p<0.05) while CNR is three times higher than system A (prototype: 329.39 ± 5.55; A: 100.29 ± 2.31; p < 0.05). The spatial resolutions recorded are 0.2446 mm in the prototype DENT and 0.5179 mm in the commercial system A. Image produced by the prototype is also better in terms of distortion level (0.03 mm in prototype, compared to 0.294 mm in A, p < 0.05). The linear relationship between bone mineral density (BMD) and image intensity of both systems were similarly performed.Conclusion: Within the limitation of this study, our prototype DENT-P001 has potential to produce better image quality than system A in terms of spatial resolution, SNR, CNR, uniformity, and distortion.

Image Quality Enhancing by Efficient Histogram Equalization

2014 ◽  
Vol 2 (2) ◽  
pp. 47-58
Author(s):  
Ismail Sh. Baqer
Keyword(s):  
Image Quality ◽  
Contrast Enhancement ◽  
Mean Squared Error ◽  
Signal To Noise Ratio ◽  
Histogram Equalization ◽  
Gray Level ◽  
Signal To Noise ◽  
Squared Error ◽  
Noise Ratio

A two Level Image Quality enhancement is proposed in this paper. In the first level, Dualistic Sub-Image Histogram Equalization DSIHE method decomposes the original image into two sub-images based on median of original images. The second level deals with spikes shaped noise that may appear in the image after processing. We presents three methods of image enhancement GHE, LHE and proposed DSIHE that improve the visual quality of images. A comparative calculations is being carried out on above mentioned techniques to examine objective and subjective image quality parameters e.g. Peak Signal-to-Noise Ratio PSNR values, entropy H and mean squared error MSE to measure the quality of gray scale enhanced images. For handling gray-level images, convenient Histogram Equalization methods e.g. GHE and LHE tend to change the mean brightness of an image to middle level of the gray-level range limiting their appropriateness for contrast enhancement in consumer electronics such as TV monitors. The DSIHE methods seem to overcome this disadvantage as they tend to preserve both, the brightness and contrast enhancement. Experimental results show that the proposed technique gives better results in terms of Discrete Entropy, Signal to Noise ratio and Mean Squared Error values than the Global and Local histogram-based equalization methods

scholarly journals Optimization of contrast medium volume for abdominal CT in oncologic patients: prospective comparison between fixed and lean body weight-adapted dosing protocols

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Damiano Caruso ◽  
Elisa Rosati ◽  
Nicola Panvini ◽  
Marco Rengo ◽  
Davide Bellini ◽  
...  
Keyword(s):  
Body Weight ◽  
Image Quality ◽  
Contrast Media ◽  
Lower Amount ◽  
Fixed Dose ◽  
Lean Body Weight ◽  
Abdominal Ct ◽  
Oncologic Patients ◽  
Noise Ratio ◽  
Parenchymal Enhancement

Abstract Background Patient body size represents the main determinant of parenchymal enhancement and by adjusting the contrast media (CM) dose to patient weight may be a more appropriate approach to avoid a patient over dosage of CM. To compare the performance of fixed-dose and lean body weight (LBW)-adapted contrast media dosing protocols, in terms of image quality and parenchymal enhancement. Results One-hundred cancer patients undergoing multiphasic abdominal CT were prospectively enrolled in this multicentric study and randomly divided in two groups: patients in fixed-dose group (n = 50) received 120 mL of CM while in LBW group (n = 50) the amount of CM was computed according to the patient’s LBW. LBW protocol group received a significantly lower amount of CM (103.47 ± 17.65 mL vs. 120.00 ± 0.00 mL, p < 0.001). Arterial kidney signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) and pancreatic CNR were significantly higher in LBW group (all p ≤ 0.004). LBW group provided significantly higher arterial liver, kidney, and pancreatic contrast enhancement index (CEI) and portal venous phase kidney CEI (all p ≤ 0.002). Significantly lower portal vein SNR and CNR were observed in LBW-Group (all p ≤ 0.020). Conclusions LBW-adapted CM administration for abdominal CT reduces the volume of injected CM and improves both image quality and parenchymal enhancement.

scholarly journals Threshold-dependent iodine imaging and spectral separation in a whole-body photon-counting CT system

2021 ◽  
Author(s):  
S. Sawall ◽  
L. Klein ◽  
E. Wehrse ◽  
L. T. Rotkopf ◽  
C. Amato ◽  
...  
Keyword(s):  
Image Quality ◽  
Photon Counting ◽  
Dual Energy ◽  
Whole Body ◽  
Dual Energy Ct ◽  
Post Mortem ◽  
Tube Voltage ◽  
Spectral Separation ◽  
Dual Source ◽  
Noise Ratio

Abstract Objective To evaluate the dual-energy (DE) performance and spectral separation with respect to iodine imaging in a photon-counting CT (PCCT) and compare it to dual-source CT (DSCT) DE imaging. Methods A semi-anthropomorphic phantom extendable with fat rings equipped with iodine vials is measured in an experimental PCCT. The system comprises a PC detector with two energy bins (20 keV, T) and (T, eU) with threshold T and tube voltage U. Measurements using the PCCT are performed at all available tube voltages (80 to 140 kV) and threshold settings (50–90 keV). Further measurements are performed using a conventional energy-integrating DSCT. Spectral separation is quantified as the relative contrast media ratio R between the energy bins and low/high images. Image noise and dose-normalized contrast-to-noise ratio (CNRD) are evaluated in resulting iodine images. All results are validated in a post-mortem angiography study. Results R of the PC detector varies between 1.2 and 2.6 and increases with higher thresholds and higher tube voltage. Reference R of the EI DSCT is found as 2.20 on average overall phantoms. Maximum CNRD in iodine images is found for T = 60/65/70/70 keV for 80/100/120/140 kV. The highest CNRD of the PCCT is obtained using 140 kV and is decreasing with decreasing tube voltage. All results could be confirmed in the post-mortem angiography study. Conclusion Intrinsically acquired DE data are able to provide iodine images similar to conventional DSCT. However, PCCT thresholds should be chosen with respect to tube voltage to maximize image quality in retrospectively derived image sets. Key Points • Photon-counting CT allows for the computation of iodine images with similar quality compared to conventional dual-source dual-energy CT. • Thresholds should be chosen as a function of the tube voltage to maximize iodine contrast-to-noise ratio in derived image sets. • Image quality of retrospectively computed image sets can be maximized using optimized threshold settings.

Model-based reconstruction algorithm in the detection of acute trauma-related lesions in brain CT examinations

2021 ◽  
pp. 197140092110087
Author(s):  
Andrea De Vito ◽  
Cesare Maino ◽  
Sophie Lombardi ◽  
Maria Ragusi ◽  
Cammillo Talei Franzesi ◽  
...  
Keyword(s):  
Image Quality ◽  
Iterative Reconstruction ◽  
Signal To Noise Ratio ◽  
Reconstruction Algorithm ◽  
Signal To Noise ◽  
Subjective Image Quality ◽  
Model Based ◽  
Hybrid Iterative Reconstruction ◽  
Noise Ratio ◽  
Enhanced Computed Tomography

Background and purpose To evaluate the added value of a model-based reconstruction algorithm in the assessment of acute traumatic brain lesions in emergency non-enhanced computed tomography, in comparison with a standard hybrid iterative reconstruction approach. Materials and methods We retrospectively evaluated a total of 350 patients who underwent a 256-row non-enhanced computed tomography scan at the emergency department for brain trauma. Images were reconstructed both with hybrid and model-based iterative algorithm. Two radiologists, blinded to clinical data, recorded the presence, nature, number, and location of acute findings. Subjective image quality was performed using a 4-point scale. Objective image quality was determined by computing the signal-to-noise ratio and contrast-to-noise ratio. The agreement between the two readers was evaluated using k-statistics. Results A subjective image quality analysis using model-based iterative reconstruction gave a higher detection rate of acute trauma-related lesions in comparison to hybrid iterative reconstruction (extradural haematomas 116 vs. 68, subdural haemorrhages 162 vs. 98, subarachnoid haemorrhages 118 vs. 78, parenchymal haemorrhages 94 vs. 64, contusive lesions 36 vs. 28, diffuse axonal injuries 75 vs. 31; all P<0.001). Inter-observer agreement was moderate to excellent in evaluating all injuries (extradural haematomas k=0.79, subdural haemorrhages k=0.82, subarachnoid haemorrhages k=0.91, parenchymal haemorrhages k=0.98, contusive lesions k=0.88, diffuse axonal injuries k=0.70). Quantitatively, the mean standard deviation of the thalamus on model-based iterative reconstruction images was lower in comparison to hybrid iterative one (2.12 ± 0.92 vsa 3.52 ± 1.10; P=0.030) while the contrast-to-noise ratio and signal-to-noise ratio were significantly higher (contrast-to-noise ratio 3.06 ± 0.55 vs. 1.55 ± 0.68, signal-to-noise ratio 14.51 ± 1.78 vs. 8.62 ± 1.88; P<0.0001). Median subjective image quality values for model-based iterative reconstruction were significantly higher ( P=0.003). Conclusion Model-based iterative reconstruction, offering a higher image quality at a thinner slice, allowed the identification of a higher number of acute traumatic lesions than hybrid iterative reconstruction, with a significant reduction of noise.

scholarly journals Evaluation of Organ Dose and Image Quality Metrics of Pediatric CT Chest-Abdomen-Pelvis (CAP) Examination: An Anthropomorphic Phantom Study

2021 ◽  
Vol 11 (5) ◽  
pp. 2047
Author(s):  
Nor Azura Muhammad ◽  
Zunaide Kayun ◽  
Hasyma Abu Hassan ◽  
Jeannie Hsiu Ding Wong ◽  
Kwan Hoong Ng ◽  
...  
Keyword(s):  
Image Quality ◽  
Multidetector Ct ◽  
Organ Dose ◽  
Quality Metrics ◽  
Ct Scanner ◽  
Image Quality Metrics ◽  
Tube Current ◽  
Significant Difference ◽  
Noise Ratio ◽  
The Impact

The aim of this study is to investigate the impact of CT acquisition parameter setting on organ dose and its influence on image quality metrics in pediatric phantom during CT examination. The study was performed on 64-slice multidetector CT scanner (MDCT) Siemens Definition AS (Siemens Sector Healthcare, Forchheim, Germany) using various CT CAP protocols (P1–P9). Tube potential for P1, P2, and P3 protocols were fixed at 100 kVp while P4, P5, and P6 were fixed at 80 kVp with used of various reference noise values. P7, P8, and P9 were the modification of P1 with changes on slice collimation, pitch factor, and tube current modulation (TCM), respectively. TLD-100 chips were inserted into the phantom slab number 7, 9, 10, 12, 13, and 14 to represent thyroid, lung, liver, stomach, gonads, and skin, respectively. The image quality metrics, signal to noise ratio (SNR) and contrast to noise ratio (CNR) values were obtained from the CT console. As a result, this study indicates a potential reduction in the absorbed dose up to 20% to 50% along with reducing tube voltage, tube current, and increasing the slice collimation. There is no significant difference (p > 0.05) observed between the protocols and image metrics.

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