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Second-generation motion correction algorithm improves diagnostic accuracy of single-beat coronary CT angiography in patients with increased heart rate
摘要： Objective To assess the effect of a second-generation motion correction algorithm on the diagnostic accuracy of coronary computed tomography angiography (CCTA) using a 256-detector row CT in patients with increased heart rates. Methods Eighty-one consecutive symptomatic cardiac patients with increased heart rates (≥ 75 beats per min) were enrolled. All patients underwent CCTA and invasive coronary angiography (ICA). CCTA was performed with a 256-detector row CT using prospectively ECG-triggered single-beat protocol. Images were reconstructed using standard (STD) algorithm, first-generation intra-cycle motion correction (MC1) algorithm, and second-generation intra-cycle motion correction (MC2) algorithm. The image quality of coronary artery segments was assessed by two experienced radiologists using a 4-point scale (1: non-diagnostic and 4: excellent), according to the 18-segment model. Diagnostic performance for segments with significant lumen stenosis (≥ 50%) was compared between STD, MC1, and MC2 by using ICA as the reference standard. Results The mean effective dose of CCTA was 1.0 mSv. On per-segment level, the overall image quality score and interpretability were improved to 3.56 ± 0.63 and 99.2% due to the use of MC2, as compared to 2.81 ± 0.85 and 92.5% with STD and 3.21 ± 0.79 and 97.2% with MC1. On per-segment level, compared to STD and MC1, MC2 improved the sensitivity (92.2% vs. 79.2%, 80.7%), specificity (97.8% vs. 82.1%, 90.8%), positive predictive value (89.9% vs. 48.4%, 65.1%), negative predictive value (98.3% vs. 94.9%, 95.7%), and diagnostic accuracy (96.8% vs. 81.5%, 89.0%). Conclusion A second-generation intra-cycle motion correction algorithm for single-beat CCTA significantly improves image quality and diagnostic accuracy in patients with increased heart rate.
关键词： Coronary angiography,Heart rate,Tomography, X-ray computed,Coronary vessels,Motion
更新于2025-09-23 15:23:52
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Vascular and structural alterations of the choroid evaluated by optical coherence tomography angiography and optical coherence tomography after half-fluence photodynamic therapy in chronic central serous chorioretinopathy
摘要： Purpose To concurrently evaluate the effect of half-fluence photodynamic therapy (hf PDT) on choriocapillaris (CC) perfusion and choroidal structure in chronic central serous chorioretinopathy (CSC). Methods This prospective study included 48 eyes of 41 patients with chronic CSC. Enhanced depth imaging optical coherence tomography and optical coherence tomography angiography (OCTA) images were analyzed. Choroidal area (CA), luminal area (LA), and stromal area (SA) were computed using Image J software. Results One month after hf-PDT, total CA decreased to 1.312 mm2 from 1.490 mm2 (p < 0.001), LA decreased to 0.981 mm2 from 1.097 mm2 (p < 0.001), and SA decreased to 0.331 mm2 from 0.393 mm2 (p < 0.001). In OCTA, the CC flow in the eyes with CSC (17.75 mm2) was statistically significantly lower than the fellow eyes (18.93 mm2) at the baseline visit (p < 0.001). After hf-PDT, the flow in the choriocapillaris statistically significantly increased to 18.81 mm2 at the first month (p = 0.02). Conclusions OCTA proves that after hf-PDT a significant increase in CC perfusion occurred at first month. The decrease of the luminal areas in enhanced depth imaging optical coherence tomography is mainly due to a decrease in large-caliber vessels, which indicates that hf-PDT has an effect on larger choroidal vessels and spares CC flow.
关键词： Chronic central serous chorioretinopathy,Optical coherence tomography angiography,Half-fluence photodynamic therapy,Choriocapillaris perfusion
更新于2025-09-23 15:23:52
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Novel method to measure the intrinsic spatial resolution in PET detectors based on monolithic crystals
摘要： The main aim of this work is to provide a method to retrieve the intrinsic spatial resolution of a gamma-ray detector block based on monolithic crystals within an assembled scanner. This method consists on a discrimination of the data using a software collimation process. The results are compared with an alternative method of separating two detector blocks far enough to produce a "virtual" source collimation due to the geometric constraints on the allowed coincidence event angles. A theoretical model has been deduced to fit the measured light distribution profiles, allowing estimating the detector intrinsic spatial resolution. The detector intrinsic spatial resolution is expected to follow a Gaussian distribution and the positron-emitter source shape, given the small size of a 22Na source with 0.25 mm in diameter, can be assumed to follow a Lorentzian profile. However, the collimation of the data modifies the source shape that is no longer a pure Lorentzian distribution. Therefore, the model is based on the convolution of a Gaussian shaped distribution (contribution of the detector) and a modified Lorentzian distribution (contribution of the collimated source profile) that takes into account the collimation effect. Three LYSO crystals geometries have been studied in the present work, namely a 10 mm thick trapezoidal monolithic block, and two rectangular monolithic blocks with thicknesses of 15 mm and 20 mm, respectively. All the blocks have size dimensions of 50 mm × 50 mm. The experimental results yielded an intrinsic detector spatial resolution of 0.64 ± 0.02 mm, 0.82 ± 0.02 and 1.07 ± 0.03 mm, for the 10 mm, 15 mm and 20 mm thick blocks, respectively, when the source was placed at the center of the detector. The detector intrinsic spatial resolution was moreover evaluated across one of the axis of each crystal. These values worsen to an average value of 0.68 ± 0.04 mm, 0.90 ± 0.14 and 1.29 ± 0.19 mm, respectively, when the whole crystal size is considered, as expected. These tests show an accurate method to determine the intrinsic spatial resolution of monolithic-based detector blocks, once assembled in the PET system.
关键词： Intrinsic spatial resolution,SiPM array,Monolithic blocks,Positron Emission Tomography,Gamma ray detectors
更新于2025-09-23 15:23:52
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Value of a smartphone-compatible thermal imaging camera in the detection of peroneal artery perforators: Comparative study with computed tomography angiography
摘要： Background: The aim of this study was to investigate the value of a smartphone-compatible thermal imaging camera in the mapping of the peroneal artery perforators. Methods: Twelve consecutive patients scheduled for fibular flap reconstruction were enrolled. The lower limbs were first studied using smartphone-based dynamic infrared thermography (DIRT). During the rewarming, the hotspots were marked, small rubber markers were taped to the registered sites, and then the patients were sent for a CT scan. The diagnostic performance of smartphone-based DIRT was evaluated by comparing the DIRT findings with CT angiography and intraoperative findings. Results: DIRT detected 42 of the 57 dominant perforators in 24 limbs and resulted in a sensitivity of 73.7% and a positive predictive value of 65.6%. Conclusions: The sensitivity and positive predictive value of the smartphone-based DIRT are low. Currently, it should be used as an adjunctive tool together with the established imaging techniques.
关键词： thermography,fibular flap,perforator mapping,peroneal artery perforator flap,computed tomography angiography
更新于2025-09-23 15:23:52
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low-coherent optical diffraction tomography by angle-scanning illumination
摘要： Temporally low-coherent optical diffraction tomography (ODT) is proposed and demonstrated based on angle-scanning Mach–Zehnder interferometry. Using a digital micromirror device based on diffractive tilting, the full-field interference of incoherent light is successfully maintained during every angle scanning sequences. Further, current ODT reconstruction principles for temporally incoherent illuminations are thoroughly reviewed and developed. Several limitations of incoherent illumination are also discussed, such as the nondispersive assumption, optical sectioning capacity, and illumination angle limitation. Using the proposed setup and reconstruction algorithms, low-coherent ODT imaging of plastic microspheres, human red blood cells, and rat pheochromocytoma cells is experimentally demonstrated.
关键词： quantitative phase imaging,low-coherent,optical diffraction tomography,coherent noise
更新于2025-09-23 15:23:52
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Evaluation of the effect of image noise on CT perfusion measurements using digital perfusion phantoms
摘要： Objectives To assess the influence of image noise on computed tomography (CT) perfusion studies, CT perfusion software algorithms were evaluated for susceptibility to image noise and results applied to clinical perfusion studies. Methods Digital perfusion phantoms were generated using a published deconvolution model to create time-attenuation curves (TACs) for 16 different combinations of blood flow (BF; 30/60/90/120 ml/100 ml/min) and flow extraction product (FEP; 10/20/30/40 ml/100 ml/min) corresponding to values encountered in clinical studies. TACs were distorted with Gaussian noise at 50 different strengths to approximate image noise, performing 200 repetitions for each noise level. A total of 160,000 TACs were evaluated by measuring BF and FEP with CT perfusion software, comparing results for the maximum slope and Patlak models with those obtained with a deconvolution model. To translate results to clinical practice, data of 23 patients from a CT perfusion study were assessed for image noise, and the accuracy of reported CT perfusion measurements was estimated. Results Perfusion measurements depend on image noise as means and standard deviations of BF and FEP over repetitions increase with increasing image noise, especially for low BF and FEP values. BF measurements derived by deconvolution show larger standard deviations than those performed with the maximum slope model. Image noise in the evaluated CT perfusion study was 26.46 ± 3.52 HU, indicating possible overestimation of BF by up to 85% in a clinical setting. Conclusions Measurements of perfusion parameters depend heavily upon the magnitude of image noise, which has to be taken into account during selection of acquisition parameters and interpretation of results, e.g., as a quantitative imaging biomarker.
关键词： Tomography, x-ray computed,Phantoms, imaging,Perfusion imaging,Software,Artifacts
更新于2025-09-23 15:23:52
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Visual assessment of calcification in solitary pulmonary nodules on chest radiography: correlation with volumetric quantification of calcification
摘要： Purpose To assess the ability of digital chest radiography (CXR) to reveal calcification in solitary pulmonary nodules (SPNs), and to examine the correlation between a visual assessment and volumetric quantification of the calcification. Materials and methods This study was a retrospective review of 220 SPNs identified by both CXR and chest CT. Eleven observers did blind review of the CXR images and scored nodule calcification on a confidence scale of 1 to 5. The area under the receiver operating characteristics (ROC) curve (AUC) was obtained to analyze the diagnostic performance. The intraclass correlation coefficient (ICC) for interrater reliability was calculated. The AUC and ICC were calculated according to the following nodule diameter groups: group 1 (< 10 mm), group 2 (≥ 10 mm and < 20 mm), and group 3 (≥ 20 mm). Results Of the 220 SPNs, 145 SPNs (65.6%) were identified as non-calcified and 75 (34.4%) as calcified. The average percentage of calcification volume in SPN > 160 HU (Vol160HU) among the 75 calcified nodules was 47.5%. The mean Vol160HU of the 68 SPNs classified as having definite calcification was 51.1%. The overall AUC was 0.71. The AUCs for groups 1, 2, and 3 was 0.835, 0.639, and 0.620, respectively. The ICCs for groups 1, 2, 3 was 0.65, 0.48, and 0.33, respectively. Conclusion The overall diagnostic performance of digital CXR to predict calcification in SPNs was moderately accurate and the diagnostic performance for predicting calcification in SPNs was significantly higher, and interobserver reproducibility was good when SPN < 10 mm compared with ≥ 10 mm in diameter.
关键词： Radiography,Solitary pulmonary nodule,Tomography,thoracic,X-ray computed
更新于2025-09-23 15:23:52
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Fundus autofluorescence and spectral domain optical coherence tomography as predictors for long-term functional outcome in rhegmatogenous retinal detachment
摘要： Purpose To detect pre- and postoperative retinal changes in fundus autofluorescence (AF) and spectral domain optical coherence tomography (SD-OCT) and to correlate these with functional outcome in patients with primary rhegmatogenous retinal detachment (RRD). Methods A prospective, 30-month study of patients operated with 25-gauge vitrectomy for primary RRD. Patients were examined preoperatively and after 6 and 30 months, using ultrawide-field AF images (UWFI) (Optos 200Tx) and SD-OCT (Topcon 3D OCT-2000) imaging. Results Of 84 patients (84 eyes) included at baseline, 100.0 and 86.9% were re-examined at month 6 and 30, respectively. Preoperative findings such as macular attachment, detachment > 750 μm from foveola, lack of intraretinal separation, and subfoveal elevation ≤ 500 μm were all associated with better BCVA at months 6 and 30. Postoperative disruption of the photoreceptor layer was associated with poor BCVA at month 6 (p < 0.001) but not at month 30. At baseline, AF-demarcation of RRD was demonstrated by a hyperfluorescent edge in 92.0% and was associated with visual impairment at months 6 (p = 0.003) and 30 (p = 0.003). Visual outcome at month 30 was good (≤ 0.3 logMAR (≥ 20/40 Snellen)), regardless of the preoperative, macular status. However, with significantly better visual outcome in patients with macula attachments versus partly or totally macular detachments (p < 0.001). Conclusion Fundus AF and SD-OCT is able to identify retinal reestablishment up to 30 months after primary RRD, with good correlation to BCVA. These findings emphasize the importance of long-term studies for final visual recovery.
关键词： Fundus autofluorescence,Rhegmatogenous retinal detachment,Long-term outcome,Vitrectomy,Visual outcome,Optical coherence tomography
更新于2025-09-23 15:23:52
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Impact of segmentation density on spectral domain optical coherence tomography assessment in Stargardt disease
摘要： Purpose Automated spectral domain optical coherence tomography (SD-OCT) segmentation algorithms currently do not perform well in segmenting individual intraretinal layers in eyes with Stargardt disease (STGD). We compared selective B-scan segmentation strategies for generating mean retinal layer thickness and preserved area data from SD-OCT scans in patients with STGD1. Methods Forty-five eyes from 40 Stargardt patients were randomly selected from the ongoing Natural History of the Progression of Atrophy Secondary to Stargardt Disease (ProgStar) study. All eyes underwent SD-OCT using a standard macular volume consisting of 1024 × 49 equally spaced B-scans within a 20 × 20 degree field centered on the fovea. All 49 B-scans were segmented manually to quantify total retina, outer nuclear layer (ONL), photoreceptor inner segments, photoreceptor outer segments (OS), and retinal pigment epithelial layer (RPE). Mean thickness and total area were generated using all 49 B-scans (spaced 122 μm apart), 25 B-scans (every other B-scan, spaced 240 μm apart), 17 B-scans (every third scan, 353 μm apart), and 13 B-scans (every fourth scan, 462 μm apart), as well as by using an Badaptive^ method where a subset (minimum 25 B-scans) of B-scans that the grader deemed as significantly different from adjacent B-scans were utilized. Mean absolute and percentage errors were calculated for macular thickness and area of different retinal layers for the different B-scan subset selection strategies relative to using all 49 B-scans, which was considered the reference or ground truth. Results Mean thickness and area measurements were significantly different for any regularly spaced reduction in B-scan density relative to the ground truth. When an adaptive approach was applied using a minimum of half the scans, the differences relative to ground truth were no longer significantly different. The mean percent differences for the area and thicknesses of the various layers ranged from 0.02 to 33.66 (p < 0.05 for all comparisons) and 0.44 to 7.24 (p > 0.05) respectively. Conclusion Manual segmentation of a subset of B-scans using an adaptive strategy can yield thickness and area measurements of retinal sublayers comparable to the reference ground truth derived from using all B-scans in the volume. These results may have implications for increasing the efficiency of SD-OCT grading strategies in clinical trials for STGD and other related macular degenerative disorders.
关键词： Stargardt,Segmentation density,Spectral domain optical coherence tomography,Retinal layers
更新于2025-09-23 15:23:52
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Multiple limited-angles computed tomography reconstruction based on multi-direction total variation minimization
摘要： Accurate computed tomography (CT) reconstruction from incomplete projections is an important research topic. Sparse sampling and limited-angle sampling are two effective ways to reduce the X-ray radiation dose or the scanning time. However, it is technically complicated to realize sparse sampling in medical CT since the tube power or the pre-patient collimator is difficult to be switched frequently. Limited-angle sampling makes it difficult to reconstruct an accurate image. The developed multiple limited-angles (MLA) sampling scheme could well balance the technical implementation complexity and the CT reconstruction difficulty. It does not require frequent switching of the tube power or the pre-patient collimator. The data correlation of the acquired projections is lower than that in limited-angle sampling. Using the projections acquired by MLA sampling, CT images reconstructed by the total variation minimization (TVM) method suffer from shading artifacts. Because the artifacts are distributed in several fixed directions, the artifact-suppression reconstruction model based on multi-direction total variation was designed for MLA CT reconstruction in this work. The multi-direction total variation minimization (MDTVM) was utilized to solve the optimization model. Experiments on digital phantoms and real projections indicated that MDTVM can better suppress the shading artifacts than TVM.
关键词： image reconstruction,total variation minimization,computed tomography,limited-angle sampling,artifacts suppression
更新于2025-09-23 15:23:52