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1.
J Comput Assist Tomogr ; 44(1): 78-82, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31939886

RESUMO

OBJECTIVE: This study aimed to evaluate virtual monochromatic images (VMIs) obtained using dual-layer dual-energy computed tomography (CT) for breast carcinoma. METHODS: We retrospectively enrolled 28 patients with breast cancer who were pathologically diagnosed using dual-layer dual-energy CT. Virtual monochromatic images (40-200 keV) were generated. We compared CT number, image noise, contrast, and contrast-to-noise ratio (CNR) between VMIs with the highest CNR and conventional CT images. We performed qualitative image analysis between VMIs at optimized energy and conventional CT images. RESULTS: Image noise of VMIs was not significantly different from that of the conventional CT images. As the x-ray energy decreased, CNR increased. The 40-keV VMIs were highest CNR and higher than that of the conventional CT images. In qualitative image analysis, the 40-keV images were significantly higher than conventional CT images. CONCLUSION: Both qualitative and quantitative analyses showed that the image quality of VMIs at 40 keV was significantly higher than that of conventional CT images.


Assuntos
Neoplasias da Mama/diagnóstico por imagem , Imagem Radiográfica a Partir de Emissão de Duplo Fóton/métodos , Tomografia Computadorizada por Raios X/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Pessoa de Meia-Idade , Intensificação de Imagem Radiográfica , Interpretação de Imagem Radiográfica Assistida por Computador , Estudos Retrospectivos , Razão Sinal-Ruído
2.
J Comput Assist Tomogr ; 44(1): 95-101, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31939889

RESUMO

PURPOSE: This study aimed to evaluate image quality of ultra-low dose chest computed tomography using 6 iterative reconstruction (IR) algorithms. METHOD: A lung phantom was scanned on 4 computed tomography scanners using fixed tube voltages and the lowest mAs available on each scanner, resulting in dose levels of 0.1 to 0.2 mGy (80 kVp) and 0.3 to 1 mGy (140 kVp) volume CT dose index (CTDIvol). Images were reconstructed with IR available on the scanners. Image noise, signal-to-noise ratios, contrast-to-noise ratios, uniformity, and noise power spectrum (NPS) were assessed for evaluation of image quality. RESULTS: Image quality parameters increased with increasing dose for all algorithms. At constant dose levels, model-based techniques improved the contrast-to-noise ratio of lesions more than the statistical algorithms. All algorithms tested at 0.1 mGy showed lower NPS peak frequencies compared with 0.39 mGy. In contrast to the statistical techniques, model-based algorithms showed lower NPS peak frequencies at the lowest doses, indicating a coarser and blotchier noise texture. CONCLUSION: This study shows the importance of evaluating IR when introduced clinically.


Assuntos
Pulmão/diagnóstico por imagem , Interpretação de Imagem Radiográfica Assistida por Computador/métodos , Tomografia Computadorizada por Raios X/instrumentação , Algoritmos , Meios de Contraste , Humanos , Imagens de Fantasmas , Doses de Radiação , Razão Sinal-Ruído
3.
J Comput Assist Tomogr ; 44(1): 138-144, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31939895

RESUMO

OBJECTIVE: The aim of this study was to determine the influence of virtual monoenergetic images (vMEIs) on renal cortex volumetry (RCV) and estimation of split-renal function. METHODS: Twenty-five patients (mean ± SD, 64.7 ± 9.9 years) underwent a contrast-enhanced dual-layer spectral detector computed tomography. Images were reconstructed with a reference standard (iterative model reconstruction, IMRRef), a newly spectral detector computed tomography algorithm (SPcon) and vMEI at 40, 60, 80, 100, and 120 keV. Two blinded independent readers performed RCV on all data sets with a semiautomated tool. RESULTS: Total kidney volume was up to 15% higher in vMEI at 40/60 keV compared with IMRRef (P < 0.001). Total kidney volume with vMEI at 80/100 keV was similar to IMRRef (P < 0.001). Split-renal function was similar in all reconstructions at approximately 50% ± 3%. Bland-Altman analysis showed no significant differences (P > 0.05), except for 40 keV versus SPcon (P < 0.05). The time required to perform RCV was reasonable, approximately 4 minutes, and showed no significant differences among reconstructions. Interreader agreement was greatest with vMEI at 80 keV (r = 0.68; 95% confidence interval, 0.39-0.85; P < 0.0002) followed by IMRRef images (r = 0.67; 95% confidence interval, 0.37-0.84; P < 0.0003). IMRRef showed the highest mean Hounsfield unit for cortex/medulla of 223.4 ± 73.7/62.5 ± 19.7 and a ratio of 3.7. CONCLUSIONS: Semiautomated RCV performed with vMEI and IMRRef/SPcon is feasible and showed no clinically relevant differences with regard to split-renal function. Low-kiloelectron volt vMEI showed greater tissue contrast and total kidney volume but no benefit for RCV. Moderate-kiloelectron volt vMEI (80 keV) results were similar to IMRRef with a faster postprocessing time.


Assuntos
Córtex Renal/diagnóstico por imagem , Interpretação de Imagem Radiográfica Assistida por Computador/métodos , Imagem Radiográfica a Partir de Emissão de Duplo Fóton/métodos , Tomografia Computadorizada por Raios X/métodos , Idoso , Algoritmos , Feminino , Humanos , Córtex Renal/patologia , Masculino , Pessoa de Meia-Idade , Variações Dependentes do Observador , Estudos Retrospectivos , Sensibilidade e Especificidade , Razão Sinal-Ruído
4.
J Comput Assist Tomogr ; 44(1): 153-159, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31939897

RESUMO

OBJECTIVE: The aim of this study was to assess the utility of 70-kilovoltage-peak (kVp) contrast-enhanced computed tomography (CECT) for visualization and identification of the right adrenal vein (RAV) in comparison with that of conventional 120-kVp CECT. METHODS: This retrospective study included patients who underwent adrenal venous sampling with concurrent biphasic 120-kVp (120-kVp group, n = 43) or 70-kVp (70-kVp group, n = 47) CECT. Signal-to-noise ratios, contrast-to-noise ratios, longitudinal lengths, conspicuity scores, RAV detection rates, and size-specific dose estimates were compared between the 2 groups. RESULTS: In comparison with the 120-kVp group, the 70-kVp group had significantly higher signal-to-noise and contrast-to-noise ratios (P < 0.001-P = 0.033), greater longitudinal lengths (P < 0.001-P = 0.002), superior conspicuity scores for the RAV (P < 0.001), higher RAV detection rates (P = 0.015-P = 0.033), and lower size-specific dose estimates (P < 0.001). CONCLUSIONS: Seventy-kilovoltage-peak CECT has advantages over conventional 120-kVp CECT and is potentially useful for noninvasive assessment of the precise anatomy of the RAV.


Assuntos
Glândulas Suprarrenais/irrigação sanguínea , Angiografia por Tomografia Computadorizada/métodos , Hiperaldosteronismo/diagnóstico por imagem , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Doses de Radiação , Estudos Retrospectivos , Sensibilidade e Especificidade , Razão Sinal-Ruído
5.
Artigo em Japonês | MEDLINE | ID: mdl-31956185

RESUMO

PURPOSE: In triggered acquisition noncontrast enhancement magnetic resonance angiography using ECG-gated with short-term inversion recovery (STIR-TRANCE), signal intensity and contrast fluctuate according to the value of refocus flip angle (RFA). We believe that we can visualize the pulmonary vascular excellently by optimized RFA which improves the signal intensity of pulmonary vascular and the contrast between pulmonary vascular and lung parenchyma. The purpose of this study is to optimize RFA in pulmonary vascular magnetic resonance angiography (MRA) imaging using STIR-TRANCE. METHOD: Pulmonary vascular MRA was performed in five normal volunteers. The department's ethics committee approved the study, and informed consent was obtained from all subjects. Before the STIR-TRANCE study, an ECG-gated single shot TSE (SS TSE) scan was performed to determine the timing of diastole. Later, the diastolic STIR-TRANCE imaging using both ECG and respiratory gating was performed with three different RFA (140 degree, 160 degree, and 180 degree). For physical evaluation, we used the signal to noise ratio (SNR) and contrast and for visual evaluation, so we used the Scheffe's method. RESULTS: SNR increases with increasing RFA. The contrast of 160 degree was significantly higher than the contrast of 180 degree. There was no significant difference in visual evaluation. CONCLUSION: From the perspective of specific absorption rate (SAR) reduction, we concluded that the optimal RFA for pulmonary vascular MRA in this study was 160 degree.


Assuntos
Eletrocardiografia , Imagem Tridimensional , Pulmão , Angiografia por Ressonância Magnética , Diástole , Humanos , Pulmão/irrigação sanguínea , Pulmão/diagnóstico por imagem , Razão Sinal-Ruído
7.
J Comput Assist Tomogr ; 43(6): 877-883, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31688248

RESUMO

PURPOSE: This study aimed to prospectively compare the image quality and visibility of urinary stone on computed tomographic (CT) images at multiple radiation exposure levels from the same patient reconstructed with sinogram-affirmed iterative reconstruction (SAFIRE). METHODS: This study included 760 patients with urinary stone who underwent CT with simultaneous acquisition at 6 exposures per patient (100% filtered back projection, 75%, 50%, 37.5%, 25%, and 12.5% SAFIRE). Two radiologists independently assessed overall image quality, noise, and stone visibility by using a 5-point scale. Quantitative measurements, including the CT number, image noise, signal-to-noise ratio, contrast-to-noise ratio (CNR), and corresponding figure of merit (FOM), were compared for 100% versus 5 other radiation doses. RESULTS: Qualitative overall image quality, noise, and stone visibility according to the location were not inferior at 37.5% exposure compared with 100% exposure, except for the visualization of smaller stones <3 mm. The signal-to-noise ratio and CNR of CT images were increased at 50% exposure compared with 100% exposure. Computed tomographic images at 37.5% exposure reconstructed with SAFIRE had significantly more noise and a lower CNR compared with CT images reconstructed with filtered back projection, based on FOMnoise and FOMCNR. The size-specific dose estimation was 4.1 ± 0.8 mGy at 37.5% exposure. CONCLUSION: Computed tomography performed at 37.5% exposure with SAFIRE may be diagnostically acceptable for the detection of clinically relevant stone.


Assuntos
Intensificação de Imagem Radiográfica/métodos , Interpretação de Imagem Radiográfica Assistida por Computador/métodos , Cálculos Urinários/diagnóstico por imagem , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Doses de Radiação , Razão Sinal-Ruído , Tomografia Computadorizada por Raios X , Adulto Jovem
8.
J Comput Assist Tomogr ; 43(6): 948-952, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31688249

RESUMO

PURPOSE: This study aimed to evaluate the image quality and degree of metal artifact reduction using the new-generation gemstone spectral imaging (GSI) and metal artifact reduction software (MARs) and to demonstrate the optimal monochromatic energy level for dual-energy cerebral computed tomography angiography (CTA) in patients with intracranial aneurysm after endovascular treatment. MATERIAL AND METHODS: A total of 20 patients with cerebral aneurysms treated with coils or clips underwent CTA using gemstone spectral computed tomography. Artifact index was calculated at each energy level with and without MARs. Signal-to-noise (SNR) and contrast-to-noise (CNR) ratios were calculated on all axial images with MARs; subjective evaluation was done by using a 4-point scale and a 3-point scale for assessing noise and vessel contrast, respectively, and compared between the monochromatic energy levels. RESULTS: The artifact index value of group GSI-MARs was significantly lower than that of group GSI at each monochromatic energy level (all, P < 0.01). Contrast-to-noise ratio and SNR of the parent arteries decreased as the energy increased from 40 to 140 keV in group GSI-MARs (all, P < 0.01). Signal-to-noise ratio and CNR between each 2 adjacent monochromatic energy level showed significant difference (all, P < 0.01). Subjective evaluation showed that a monochromatic energy level between 40 and 70 keV provided the optimal image quality. CONCLUSION: Gemstone spectral imaging with MARs could reduce metal artifacts and improve the image quality of cerebral CTA after coil or clip treatment. The new generation of GSI could provide better CNR and SNR at lower energy level, and the best image quality was obtained at energy level 40 to 70 keV for GSI-MARs.


Assuntos
Procedimentos Endovasculares/métodos , Aneurisma Intracraniano/diagnóstico por imagem , Aneurisma Intracraniano/cirurgia , Intensificação de Imagem Radiográfica/métodos , Adulto , Idoso , Artefatos , Angiografia por Tomografia Computadorizada , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Interpretação de Imagem Radiográfica Assistida por Computador/métodos , Estudos Retrospectivos , Razão Sinal-Ruído , Software
9.
Chem Commun (Camb) ; 55(95): 14367-14370, 2019 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-31720598

RESUMO

A target triggered dual-DNA machine, consisting of one rolling circle amplification (RCA)-based circular DNA machine (RCA-CDM) and one cyclical strand displacement amplification (CSDA)-based bidirectional DNA machine (CSDA-BDM), was developed for robust miRNA determination.


Assuntos
DNA/genética , Engenharia Genética , MicroRNAs/análise , Transdução de Sinais/genética , Razão Sinal-Ruído , Humanos , MicroRNAs/genética , Técnicas de Amplificação de Ácido Nucleico
10.
Medicine (Baltimore) ; 98(44): e17638, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31689772

RESUMO

INTRODUCTION: Mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) was shown to have a transient reduction in diffusion. Such changes would be used as an early detection to reduce excessive treatments and promote recovery without sequelae. The current research evaluated the high b-value (b = 3000 s/mm) diffusion-weighted imaging (DWI) assessment in MERS. METHODS: Sixteen pediatric patients showed MERS used DWI (b = 1000 and 3000 s/mm). To record number of lesions, the signal intensities, signal-to-noise ratios (SNRs), contrast-to-noise ratios (CNRs), contrast ratios (CRs), the apparent diffusion coefficients (ADCs) were measured in the normal parenchyma and lesions. RESULTS: Lesions were more apparent with high b-value. The ADC values and CNR in the lesions and surrounding normal brain parenchyma were relatively low at a high compared to standard b-value DWI (SNR: 144.67 ±â€Š33.03, 85.72 ±â€Š31.50; CNR: 20.82 ±â€Š17.64, 49.62 ±â€Š33.06; for b = 1000 and 3000 s/mm). The CR was significantly higher at a high compared to low b-value DWI (CR: 0.06 ±â€Š0.07 versus 0.40 ±â€Š0.14). CONCLUSION: High b-value DWI could detect more lesions and could obviously improve the detection of lesions in pediatric patients with MERS.


Assuntos
Encefalopatias/diagnóstico , Encefalopatias/patologia , Corpo Caloso/diagnóstico por imagem , Corpo Caloso/patologia , Encefalopatias/diagnóstico por imagem , Criança , China , Imagem de Difusão por Ressonância Magnética , Feminino , Humanos , Interpretação de Imagem Assistida por Computador , Masculino , Estudos Retrospectivos , Sensibilidade e Especificidade , Índice de Gravidade de Doença , Razão Sinal-Ruído
11.
Medicine (Baltimore) ; 98(44): e17640, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31689773

RESUMO

Diffusion-weighted imaging (DWI) plays an important role in the diagnosis of breast cancer as well as the evaluation of treatment effects. A novel technique named b-value map based on thresholded DWI images has been proposed and can achieve good contrast for demonstrating prostate lesions only by manipulating the window width and center of the images. Its application on the breast has not yet explored, so the aim of the study was to investigate the feasibility of b-value maps based on threshold DWI for detection of breast cancer. A total of 25 patients with pathologically proven invasive ductal breast carcinoma were included and underwent preoperative magnetic resonance imaging (MRI) examinations including DWI at 3T. The capabilities to display lesions of DWIb=800, b-value maps and optimal computed DWI (cDWI) images were evaluated by using a 4-point method of scoring. Apparent diffusion coefficient (ADC) values of lesions were measured for the breast carcinoma. Mean scores indicating the display capability were compared among DWIb=800, optimal cDWI and b-value maps by using Kruskal-Wallis test followed by Nemenyi test. The scores of both b-value maps (3.92 ±â€Š0.28) and optimal cDWI images (3.80 ±â€Š0.41) were higher than that of DWIb=800 (3.48 ±â€Š0.51), with statistical differences (P = .001 and P = .033, respectively). The optimal b values for manifesting breast carcinoma based on cDWI were 1000 to 1200 s/mm. The b-value map enables fast identification for breast lesions and shows similar performance to the optimal cDWI images.


Assuntos
Neoplasias da Mama/diagnóstico por imagem , Neoplasias da Mama/patologia , Imagem de Difusão por Ressonância Magnética/métodos , Interpretação de Imagem Assistida por Computador/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos de Viabilidade , Feminino , Humanos , Pessoa de Meia-Idade , Razão Sinal-Ruído
12.
J Comput Assist Tomogr ; 43(6): 919-925, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31738205

RESUMO

OBJECTIVES: The objective of this study was to compare gadobutrol-enhanced gradient-echo sequence (GRE) acquisition with T2-prepared non-contrast-enhanced steady-state free precession (SSFP) in coronary magnetic resonance angiography at 1.5 T. METHODS: Twenty-one subjects successfully completed GRE and SSFP acquisition. Signal-to-noise ratio (SNR), contrast-to-noise ratio, image quality, sharpness, visibility, length, and lumen diameter of vessels were analyzed by 2 experienced radiologists. RESULTS: The SNR at whole left circumflex artery, left main artery, and proximal left descending artery (LAD) was significantly higher in SSFP acquisition (P < 0.05). The SNR of distal LAD was slightly higher in GRE acquisition (P < 0.05). The contrast-to-noise ratio at distal LAD, proximal and distal RCA were significantly higher with GRE acquisition (P < 0.05). CONCLUSIONS: Double-dose gadobutrol-enhanced GRE and unenhanced SSFP coronary magnetic resonance angiography at 1.5 T have their own characteristics, and the combined use of the 2 methods may be taken into consideration.


Assuntos
Doença da Artéria Coronariana/diagnóstico por imagem , Processamento de Imagem Assistida por Computador/métodos , Imagem Tridimensional/métodos , Adulto , Feminino , Humanos , Interpretação de Imagem Assistida por Computador/métodos , Angiografia por Ressonância Magnética , Imagem Cinética por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Compostos Organometálicos/administração & dosagem , Respiração , Razão Sinal-Ruído
13.
J Comput Assist Tomogr ; 43(6): 943-947, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31738210

RESUMO

OBJECTIVE: Silent magnetic resonance angiography (MRA) was compared with time-of-flight (TOF)-MRA in imaging of arteriovenous malformations (AVMs) of the brain. METHODS: Thirty-five consecutive patients with AVMs of the brain were included. Quantitative analyses were performed by measuring both signal-to-noise ratio and contrast-to-noise ratio of the nidus. Qualitative analysis (scores 1-4) was performed by evaluating depictions of feeding arteries and draining veins independently by 2 reviewers. RESULTS: Both signal-to-noise ratio and contrast-to-noise ratio in TOF-MRA were significantly higher than those in silent MRA. For both feeders and drainers, scores were significantly higher in silent MRA than in TOF-MRA for both reviewers. Interrater agreement was higher in silent MRA than in TOF-MRA. CONCLUSIONS: Silent MRA visualized feeders and drainers in AVMs significantly better than did TOF-MRA. Interrater agreement was also better in silent MRA.


Assuntos
Angiografia Digital/métodos , Malformações Arteriovenosas Intracranianas/diagnóstico por imagem , Angiografia por Ressonância Magnética/métodos , Adolescente , Adulto , Feminino , Humanos , Imagem Tridimensional , Masculino , Pessoa de Meia-Idade , Intensificação de Imagem Radiográfica , Razão Sinal-Ruído , Adulto Jovem
14.
Chem Commun (Camb) ; 55(96): 14442-14445, 2019 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-31724668

RESUMO

We firstly perpared liposome coated [Ir(pq)2(bpy)]Cl (Ir@liposome) as a transducer for radiopharmaceutical (18F-FDG) excited phosphorescence imaging (REPI). Ir@liposome-based REPI exhibited deep tissue penetration and high signal-to-noise ratio in the tumor.


Assuntos
Complexos de Coordenação/química , Irídio/química , Nanopartículas/química , Imagem Óptica/métodos , Compostos Radiofarmacêuticos/química , Animais , Linhagem Celular Tumoral , Fluordesoxiglucose F18/química , Humanos , Lipossomos/química , Camundongos , Razão Sinal-Ruído
15.
Medicine (Baltimore) ; 98(48): e18207, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31770279

RESUMO

Few indexes are available for nuclear medicine image quality assessment, particularly for respiratory blur assessment. A variety of methods for the identification of blur parameters has been proposed in literature mostly for photographic pictures but these methods suffer from a high sensitivity to noise, making them unsuitable to evaluate nuclear medicine images. In this paper, we aim to calibrate and test a new blur index to assess image quality.Blur index calibration was evaluated by numerical simulation for various lesions size and intensity of uptake. Calibrated blur index was then tested on gamma-camera phantom acquisitions, PET phantom acquisitions and real-patient PET images and compared to human visual evaluation.For an optimal filter parameter of 9, non-weighted and weighted blur index led to an automated classification close to the human one in phantom experiments and identified each time the sharpest image in all the 40 datasets of 4 images. Weighted blur index was significantly correlated to human classification (ρ = 0.69 [0.45;0.84] P < .001) when used on patient PET acquisitions.The provided index allows to objectively characterize the respiratory blur in nuclear medicine acquisition, whether in planar or tomographic images and might be useful in respiratory gating applications.


Assuntos
Aumento da Imagem/métodos , Medicina Nuclear , Tomografia por Emissão de Pósitrons , Algoritmos , Humanos , Medicina Nuclear/métodos , Medicina Nuclear/normas , Tomografia por Emissão de Pósitrons/instrumentação , Tomografia por Emissão de Pósitrons/métodos , Tomografia por Emissão de Pósitrons/normas , Razão Sinal-Ruído
16.
Zhong Nan Da Xue Xue Bao Yi Xue Ban ; 44(9): 1048-1054, 2019 Sep 28.
Artigo em Chinês | MEDLINE | ID: mdl-31645496

RESUMO

OBJECTIVE: To explore the value of the third generation dual-source computed tomography (CT) convolution kernel in display of pulmonary ground-glass nodule (GGN) in transverse image reconstruction.
 Methods: A total of 52 lung adenocarcinoma patients with lung CT data were selected from February 2018 to January 2019 for this study. The pulmonary CT data were reconstructed by convolutional nucleus B157, Br54, and Br49. The signal-to-noise ratio (SNR), the contrast-to-noise ratio (CNR), and the standard deviation (SD) of the image at the GGN were used as the objective evaluation standard of image quality. Subjective image quality was scored by 2 radiologists from 3 aspects (overall image quality, noise, and lesion outline).
 Results: Objective image quality evaluation, SNR and CNR of reconstructed convolution kernel Br49 (SNR: 11.36±5.39, CNR: 7.19±4.29), Br54 (SNR: 8.30±3.35, CNR: 5.09±2.86) are greater than those of Bl57 (SNR: 4.18±2.10, CNR: 3.25±1.78; all P<0.01). SD of reconstructed convolution kernel Br49 (61.80±20.17) and Br54 (80.45±20.31) is smaller than that of Bl57 (137.92±31.11, both P<0.01). In the subjective image quality evaluation, the overall image quality score 5.0(4.5, 5.0) of Br54 was higher than that of all other images [Br49: 3.0(3.0, 4.0), Bl57: 3.0(3.0, 3.5); both P<0.05]. The Br54 image showed that the lesion contour ability score 5.0(4.0, 5.0) was higher than all other images [Br49: 4.0(4.0, 5.0), Bl57: 3.0(3.0, 3.0); both P<0.05]; Br49 image noise score 3.0(3.0, 3.0) is the lowest one [Br54 4.0(4.0, 4.0), Bl57 5.0(5.0, 5.0); both P<0.05].
 Conclusion: The reasonable selection of CT convolution kernel plays an important role in the subjective and objective image quality of GGN. It is suggested that Br54 should be used as the reconstruction of convolutional kernel in pulmonary ground glass nodules, which is helpful for doctors to find and diagnose GGN.


Assuntos
Interpretação de Imagem Radiográfica Assistida por Computador , Tomografia Computadorizada por Raios X , Algoritmos , Humanos , Doses de Radiação , Razão Sinal-Ruído
17.
Eur J Radiol ; 119: 108659, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31520930

RESUMO

PURPOSE: To evaluate image quality (IQ) and radiation dose in cone-beam computed tomography (CBCT) of the ankle using a novel twin robotic X-ray system. METHOD: We examined 16 cadaveric ankles with standard-dose (FD) and low-dose (LD) protocols using the new system's CBCT mode. For comparison, we performed multi-slice CT imaging (MSCT) with a clinical protocol. Three radiologists assessed IQ, noise and artifacts in bone and soft tissue on a five-point Likert scale (1= poor IQ; strong noise or artifacts; 5= excellent IQ; minimal noise or artifacts). Volume CT dose indices (CTDIvol) were calculated for radiation dose comparison between CBCT and MSCT. RESULTS: Overall IQ was described as very good or excellent by reader 1/2/3 in 62.5/87.5/56.3% of LD, 87.5/87.5/81.3% of FD and 100/87.5/87.5% of MSCT studies. Readers agreed that IQ was better in MSCT than LD (R1/R2/R3; p ≤ 0.008), two also found advantages of MSCT over FD (R1/R3; p ≤ 0.034). Soft tissue noise and artifacts were stronger in FD (all p ≤ 0.002) and LD (all p ≤ 0.001). In bone, artifacts and noise were also more severe in LD (all p < 0.001) and FD (all p ≤ 0.003). CTDIvol for clinical MSCT scans without dose modulation (15.0 ± 0.0 mGy) were higher than for FD (5.3 ± 1.0 mGy) and LD studies (2.9 ± 0.6 mGy; both p < 0.001). CONCLUSIONS: Despite MSCT providing better overall IQ than the twin robotic X-ray system's CBCT mode, both cone-beam protocols offer very good IQ in most studies and are suitable for clinical ankle imaging. Standard-dose and especially low-dose CBCT studies deliver up to five times less radiation dose than MSCT imaging.


Assuntos
Articulação do Tornozelo/diagnóstico por imagem , Tomografia Computadorizada de Feixe Cônico/normas , Doses de Radiação , Robótica/normas , Artefatos , Cadáver , Tomografia Computadorizada de Feixe Cônico/instrumentação , Tomografia Computadorizada de Feixe Cônico/métodos , Desenho de Equipamento , Humanos , Imagens de Fantasmas , Robótica/métodos , Razão Sinal-Ruído , Tomógrafos Computadorizados/normas , Raios X
18.
Phys Med ; 64: 10-15, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31515008

RESUMO

The standard approach to signal difference-to-noise ratio (SDNR) analysis requires a region of interest (ROI) positioned within the object to measure signal-difference, restricting this metric to flat-topped objects with large, sharply delineated areas. This work develops a generalized expression for SDNR (SDNRg) calculated from a ROI encompassing the object. Signal power, defined as the deviation of pixel values from the mean background due to the object, is used instead of signal-difference. Comparison was first made by simulating ideal flat-topped discs with sharp edges and diameters between 1 and 80 pixels, into a uniformly noisy background using a known signal-difference. For discs covering more than 20 pixels, SDNRg and standard SDNR (SDNRst) were within 3%, while for discs of less than 20 pixels, SDNRg was within 26% of the truth compared to 58% for SDNRst. Generalized and standard SDNR were compared for radiography images of three different phantoms with microcalcification-like objects (MTM-100 phantom), hemispheric objects of different thicknesses with a Gaussian intensity distribution and mammography quality control (QC) images. Applied to Gaussian details, SDNRg was between 20% and 45% higher than SDNRst, depending on object thickness, while for the QC images, SDNRg was with 1.7% of the standard SDNR. Compared to the standard SDNR, SDNRg is applicable to non-uniform signals, where an explicit contrast measurement is not suitable, and has improved accuracy when assessing SDNR of small objects.


Assuntos
Processamento de Imagem Assistida por Computador/métodos , Mamografia , Razão Sinal-Ruído
19.
Phys Med ; 64: 252-260, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31515028

RESUMO

PURPOSE: This study demonstrates a proof of concept of a method for simultaneous anatomical imaging and real-time (SMART) passive device tracking for MR-guided interventions. METHODS: Phase Correlation template matching was combined with a fast undersampled radial multi-echo acquisition using the white marker phenomenon after the first echo. In this way, the first echo provides anatomical contrast, whereas the other echoes provide white marker contrast to allow accurate device localization using fast simulations and template matching. This approach was tested on tracking of five 0.5 mm steel markers in an agarose phantom and on insertion of an MRI-compatible 20 Gauge titanium needle in ex vivo porcine tissue. The locations of the steel markers were quantitatively compared to the marker locations as found on a CT scan of the same phantom. RESULTS: The average pairwise error between the MRI and CT locations was 0.30 mm for tracking of stationary steel spheres and 0.29 mm during motion. Qualitative evaluation of the tracking of needle insertions showed that tracked positions were stable throughout needle insertion and retraction. CONCLUSION: The proposed SMART tracking method provided accurate passive tracking of devices at high framerates, inclusion of real-time anatomical scanning, and the capability of automatic slice positioning. Furthermore, the method does not require specialized hardware and could therefore be applied to track any rigid metal device that causes appreciable magnetic field distortions.


Assuntos
Imagem por Ressonância Magnética/instrumentação , Processamento de Imagem Assistida por Computador , Razão Sinal-Ruído , Fatores de Tempo , Tomografia Computadorizada por Raios X
20.
Phys Med ; 64: 89-97, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31515040

RESUMO

PURPOSE: To evaluate the feasibility of spatio-temporal generalisation of mathematical methods for protocol optimisation in interventional radiology. MATERIALS AND METHODS: Two model observers were considered:Furthermore, Low Contrast Detectability (LCD) was evaluated with a generalised statistical method by taking into account the noise integration capability of the human eye. A series of two alternative force choices (2AFC) experiments performed by four observers were used to evaluate the reliability of the proposed models. The evaluation of the mathematical methods was performed by comparing their results to the human observer performances in two steps: 1. Firstly, a series of simulated images were used to tune the models 2. In the second phase, tuned models were applied both to simulated images and actual images obtained with a commercial phantom to evaluate detectability scores. RESULTS: Evaluation with simulated images shows a good agreement with 2AFC results (RMSE < 10%). Phantom-based evaluations show a general decrease of such agreement, characterized by an RMSE lower than 16%. CONCLUSIONS: The agreement with human observer experiments supports the feasibility of the proposed generalisations. Thus, they could be introduced in quality control programmes for a deeper protocol-characterisation or for clinical protocol-optimization when dynamic images are involved.


Assuntos
Angiografia , Razão Sinal-Ruído , Estudos de Viabilidade , Processamento de Imagem Assistida por Computador , Imagens de Fantasmas
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