Assessment of recommended and acceptable image quality indicators’ values, based on materials, obtained with various aerial surveying systems for mapping purposes

The results of fine quality indicators assessment for images, obtained with various aerial surveying systems for mapping purposes are presented. The values of parameters that characterize technical conditions, technical parameters of airborne imaging and technologic settings for imagery postprocessing, natural conditions of aerial surveying are determined. The author presents a comparative analysis of fine quality indicators assessment both for photos, the quality of which was found to be satisfactory as production technical control results and those rejected due to some relevant indicators (haze, blurring, etc) and accepted unsuitable for creating cartographic products based on them. It is shown, that some quality indicators, such as spatial resolution, sharpness and the degree (standard deviation) of random noise, are advisable to be determined at performing factory calibration of aerial cameras and included in certificate as well as other calibration parameters as metrological characteristics of the obtained imagery. Acceptable values of fine quality indicators, obtained during joint analysis of previous theoretical researches results and experimental verification, based on images, obtained by various aerial surveying systems for mapping purposes were generalized and recommended during the research.

Follow-up imaging of clipped intracranial aneurysms with 3-T MRI: comparison between 3D time-of-flight MR angiography and pointwise encoding time reduction with radial acquisition subtraction-based MR angiography

OBJECTIVE Metallic susceptibility artifact due to implanted clips is a major limitation of using 3D time-of-flight magnetic resonance angiography (TOF-MRA) for follow-up imaging of clipped aneurysms (CAs). The purpose of this study was to compare pointwise encoding time reduction with radial acquisition (PETRA) subtraction-based MRA with TOF-MRA in terms of imaging quality and visibility of clip-adjacent arteries for use in follow-up imaging of CAs. METHODS Sixty-two patients with 73 CAs were included retrospectively in this comparative study. All patients underwent PETRA-MRA after TOF-MRA performed simultaneously with 3-T MRI between September 2019 and March 2020. Two neuroradiologists independently compared images obtained with both MRA modalities to evaluate overall image quality using a 4-point scale and visibility of the parent artery and branching vessels near the clips using a 3-point scale. Subgroup analysis was performed according to the number of clips (less-clipped [1–2 clips] vs more-clipped [≥ 3 clips] aneurysms). The ability to detect aneurysm recurrence was also assessed. RESULTS Compared with TOF-MRA, PETRA-MRA showed acceptable image quality (score of 3.97 ± 0.18 for TOF-MRA vs 3.73 ± 0.53 for PETRA-MRA) and had greater visibility of the adjacent vessels near the CAs (score of 1.25 ± 0.59 for TOF-MRA vs 2.27 ± 0.75 for PETRA-MRA, p < 0.0001). PETRA-MRA had greater visibility of vessels adjacent to less-clipped aneurysms (score of 2.39 ± 0.75 for less-clipped aneurysms vs 2.09 ± 0.72 for more-clipped aneurysms, p = 0.014). Of 73 CAs, aneurysm recurrence in 4 cases was detected using PETRA-MRA. CONCLUSIONS This study demonstrated that PETRA-MRA is superior to TOF-MRA for visualizing adjacent vessels near clips and can be an advantageous alternative to TOF-MRA for follow-up imaging of CAs.

Optimization of cone beam computed tomography for the assessment of alterations of the maxillary sinuses

Objective: To test the standard protocols of a CBCT unit in order to find lower-dose alternatives with diagnostically acceptable image quality for the maxillary sinuses visualization. Study design: An observational study was performed. Two dry skulls were used to simulate four conditions of the maxillary sinuses: normality, mucous retention pseudocyst, membrane thickening and bone graft. Cone beam computed tomography scans were obtained with an i-CAT classic unit using different acquisition protocols and a box of polystyrene to simulate soft tissue attenuation. All the protocols were established by the manufacturer, combining different energy parameters, fields of view and voxel sizes. Multiplanar reconstructions were presented to three Oral Radiologists through blind and randomized distribution. The specialists judged general image quality, sharpness, contrast, and the presence of noise and artifacts based on a 4-points scale. Results: Protocols with higher energy parameters had significant association with higher scores for general quality, sharpness and contrast (p<0.05). Protocols with intermediate level of radiation dose had also significant association with good and excellent image quality; for the presence of noise and artifacts the images were rated acceptable. Conclusion: i-CAT default protocols with lower dose of radiation were able to deliver acceptable image quality for the visualization of the maxillary sinuses.

Fusion of medical images in wavelet domain: an algorithmic model

Introduction: Image Fusion techniquesconsist of three stages: extraction of features, reduction of dimensions, and classification. Problem: This paper presents a novel approach for Multiresolution analysis. Objective: It is most widely used in image fusion science, which captures the features of an image not only at different resolutions, but also at different orientations. Methodology: This Wavelet based algorithm has additional advantages of fast implementation, versatility, auxiliary memory saving, complete reconstruction properties and simplicity as wavelet transformation was used. Results: The simulation results of the MRI and CT images show perfectly acceptable image quality and cover disease detection in the subsequent final image. Conclusion: Principal Component Analysis (PCA) based on fusion algorithms will empower medical researchers or clinicians to properly apply image fusion and data transmission, which leads to better care practices to minimize redundancies and can also handle data loss. Originality: Fusing images can decrease the image size, which can decrease the bandwidth when transmitting images. This also compresses the images; here an attempt is made to retain the same consistency. Limitations: As this is still a relatively novel method, mistakes with regard to the handling of clinical data may prompt treatment deficiencies for the patient. Image quality must not be diminished with this usage

COMPARISON OF THE CALCULATED WORKING RANGE OF THE THIRD GENERATION EOS AND MATRIX FOR NEAR IR RANGE

In the course of work on the master's thesis the analysis of daytime and night-time devices was carried out. The analysis showed that devices based on CCD-matrixes prevail in this segment, but the devices of this type cannot be fully called night devices, because the sensitivity of the matrixes used in their designs does not allow to observe without illumination at natural night illumination of 10-3 lux. It is known that IR illumination is a strong unmasking factor.EOS can provide acceptable image quality in natural nightlight. But their use in day-night devices has limitations. Under prolonged exposure to high light, the photocathode of EOS quickly becomes unusable, so when developing a day-night device must provide EOS protection from daylight. Thus it was decided to use CMOS-matrix as an image receiver in the night channel. This, in turn, solves several problems at once. When using the photoreceiver there is no need for mechanical switching between the channels, as there is no danger of light. Also the spectral range of sensitivity of CMOS-matrixes is much more various than that of CCD and EOS that allows to pick up an optimum range of frequencies and to refuse illumination at normal night illumination. In this article a comparison of the calculated range of detection of the device on the basis of EOS of 3 generation with the device in which as the image receiver CMOS-matrix is used.

The screening episode: visual acuity, mydriasis, and digital photography

Early eye screening detection and treatment is fundamental in managing significant complications of chronic disease, both for improving diabetic retinopathy (DR) clinical outcomes and improving the economic burdens. Early detection and subsequent treatment can substantially reduce the risk of blindness from DR. This chapter will review the screening episode, measuring visual acuity, drop instillation, contraindications, and correct camera operation. It will review problems associated with incorrect camera operation and the NHS Diabetic Eye Screening Programme (NHSDESP) standards of acceptable image quality. This will guide the screener in obtaining clear, well-centred, gradable digital images of the retina in diabetic patients with vision better than no perception of light in both eyes, as well as providing a greater understanding of issues associated with screening.

Potential for dose reduction in CT emphysema densitometry with post-scan noise reduction: a phantom study

Objective: The aim of this phantom study was to investigate the effect of scan parameters and noise suppression techniques on the minimum radiation dose for acceptable image quality for CT emphysema densitometry. Methods: The COPDGene phantom was scanned on a third generation dual-source CT system with 16 scan setups (CTDIvol 0.035–10.680 mGy). Images were reconstructed at 1.0/0.7 mm slice thickness/increment, with three kernels (one soft, two hard), filtered backprojection and three grades of third-generation iterative reconstruction (IR). Additionally, deep learning-based noise suppression software was applied. Main outcomes: overlap in area of the normalized histograms of CT density for the emphysema insert and lung material, and the radiation dose required for a maximum of 4.3% overlap (defined as acceptable image quality). Results: In total, 384 scan reconstructions were analyzed. Decreasing radiation dose resulted in an exponential increase of the overlap in normalized histograms of CT density. The overlap was 11–91% for the lowest dose setting (CTDIvol 0.035mGy). The soft kernel reconstruction showed less histogram overlap than hard filter kernels. IR and noise suppression also reduced overlap. Using intermediate grade IR plus noise suppression software allowed for 85% radiation dose reduction while maintaining acceptable image quality. Conclusion: CT density histogram overlap can quantify the degree of discernibility of emphysema and healthy lung tissue. Noise suppression software, IR, and soft reconstruction kernels substantially decrease the dose required for acceptable image quality. Advances in knowledge: Noise suppression software, IR, and soft reconstruction kernels allow radiation dose reduction by 85% while still allowing differentiation between emphysema and normal lung tissue.

Reversible Steganographic Scheme for AMBTC-Compressed Image Based on (7,4) Hamming Code

In recent years, compression steganography technology has attracted the attention of many scholars. Among all image compression method, absolute moment block truncation coding (AMBTC) is a simple and effective compression method. Most AMBTC-based reversible data hiding (RDH) schemes do not guarantee that the stego AMBTC compression codes can be translated by the conventional AMBTC decoder. In other words, they do not belong to Type I AMBTC-based RDH scheme and easily attract malicious users’ attention. To solve this problem and enhance the hiding capacity, we used (7,4) hamming code to design a Type I AMBTC-based RDH scheme in this paper. To provide the reversibility feature, we designed a prediction method and judgement mechanism to successfully select the embeddable blocks during the data embedding phase and data extraction and recovery phase. In comparing our approach with other BTC-based schemes, it is confirmed that our hiding capacity is increased while maintaining the limited size of the compression codes and acceptable image quality of the stego AMBTC-compressed images.

2516 Ultra-low Na18F tracer dosing for preclinical skeletal imaging enables new concepts in digital PET/CT

OBJECTIVES/SPECIFIC AIMS: The aim of this study was to assess the ultra-dose Na18F dPET protocol feasibility for skeleton imaging in a canine model with reduced radiation dose and preserved quantitative characteristics. We hypothesized that administering an ultra-low Na18F dose would provide suitable image quality while reducing subject’s exposure to radiation. METHODS/STUDY POPULATION: In total, 13 adult male beagles [weight (kg) mean±SD; 14.3±2.2] were scanned. The dogs were administered 3 different Na18F doses: 3 (standard dose/SD), 1 (low dose/LD), and 0.05 (ultra-low dose/ULD) mCi. Imaging started ≃45 minutes post injection for ≃ 33 minute total acquisition time. Covering the whole body, 11 bed positions, acquiring 120 (3 mCi) and 180 (1, 0.05 mCi) seconds per bed position. All imaging was performed on a digital photon counting system (Philips Vereos, pre-commercial release). PET list mode data were reconstructed using Time-of-flight with 4, 2, and 1 mm3 voxel volumes. Point spread function, and Gaussian filtering were applied. Two experienced blinded readers evaluated image sets overall quality, tissue characterization, and quality of background in the whole body skeleton. Three-dimensional (3D) regions of interest (ROI) were traced over the distal femur, first lumbar vertebra, and a portion of the liver, recording standard uptake values (SUVmax and SUVmean). RESULTS/ANTICIPATED RESULTS: All the scans and reconstructions were successfully completed in all subjects. Decreasing Na18F dose from the standard dose (3 mCi) to the ultra-low dose/ULDO (0.05 mCi), demonstrated acceptable image quality and quantification. Ultra-low dose Na18F SUVmean values for the 3D ROIs reported (mean±SD) 2.6±0.7, 2.5±1.1, 9±1.6, and 0.6±0.3 from the right and left distal femur, first lumbar vertebra, and a portion of the liver, respectively. When compared the SD with the LD and ULD, dPET demonstrated acceptable image quality and definition for qualitative overall assessment. This was also found for the overall quantitative ROI assessment of the healthy canine skeletons. DISCUSSION/SIGNIFICANCE OF IMPACT: Ultra-low dose Na18F at a level of 50 μCi for a 14 kg canine appears to be diagnostically feasible and a robust option to reduce (60-fold) radiotracer doses in a translational animal model using a dPET system. Furthermore, it allows us to move preclinical nuclear medicine imaging forward with substantial reduced exposure levels while preserving image quality. Both visual and quantitative results indicate that the standard-dose bone Na18F dPET can be decreased with a satisfactory diagnostic image quality. Ultra-low Na18F dose is indeed important for younger populations, control patients, and nononcological diseases/conditions. Favorable pharmacokinetics of Na18F (such as high bone uptake, minimal binding to serum proteins, rapid single-pass extraction, and fast clearance from the soft tissues) in addition to the technological capabilities of dPET/CT demonstrated feasibility enabling dose reduction strategies. Ultra-low dose has diagnostic reproducibility and lower radiation burden compared with higher fixed dose techniques in current available guidelines [Society of Nuclear Medicine and Molecular Imaging; SNMMI (5–10 mCi)]. Na18F dPET/CT provides higher sensitivity and diagnostic accuracy, which enables high-quality images with lower tracer activity in this translational animal model. Future research will apply the same methodology to other anatomical targets as well as to the use of different tracers. Preclinical nuclear medicine imaging using ultra-low tracer doses, demonstrated the potential to obtain reasonable quality images and diminishing radiation surveillance in accordance with as low as reasonably achievable tracer levels.