Objective: Standardizing image acquisition protocols and image quality across cameras is an important need in imaging, in particular in multi-center clinical trials and the use of image analysis and machine learning algorithms. The objective of this study was to examine the effect of ordered subset expectation maximization (OSEM) reconstruction parameters on the quantitative image quality of cardiac perfusion SPECT images in different typical SPECT cameras and therefore assess the need to change the parameter values across cameras. Methods: The analysis was carried out by comparing the defect contrast-to-noise ratio (CNR) at 12 OSEM subset-iteration combinations. Eight frames were reconstructed using the SIMIND Monte Carlo Simulation package. An activity of 370 MBq (10mCi) and projection acquisition interval of 20 seconds per projection were used. Attenuation (AC) and scatter corrections (SC) were performed in this study for all images. Results: The 16-2 subset-iteration combination yielded the highest CNR and defect contrast values for both cameras. The difference between CNR values for two cameras was found to be close to 5%. Conclusions: Monte Carlo simulations can be useful to investigate how quantitative image quality behaves with respect to reconstruction parameters and correction algorithms in a controlled environment. In this study, the use of different camera brands did not seem to significantly affect the lesion detectability. Further simulations with more extended range of parameters and camera brands may be conducted in the future to quantify further the variability between different brands of cameras.

Multiple myeloma (MM) is a hematologic cancer characterized by clonal proliferation of plasma cells within the bone marrow. It is the most serious form of plasma cell dyscrasias, whose complications—hypercalcemia, renal failure, anemia, and lytic bone lesions—are severe and justify the therapeutic management. Imaging of bone lesions is a cardinal element in the diagnosis, staging, study of response to therapy, and prognostic evaluation of patients with MM. Historically, the skeletal radiographic workup (SRW), covering the entire axial skeleton, has been used to detect bone lesions. Over time, new imaging techniques that are more powerful than SRW have been evaluated. Low-dose and whole-body computed tomography (CT) supplants SRW for the detection of bone involvement, but is of limited value in assessing therapeutic response. Bone marrow MRI, initially studying the axial pelvic-spinal skeleton and more recently the whole body, is an attractive alternative. Beyond its non-irradiating character, its sensitivity for the detection of marrow damage, its capacity to evaluate the therapeutic response and its prognostic value has been demonstrated. This well-established technique has been incorporated into disease staging systems by many health systems and scientific authorities. Along with positron emission tomography (PET)-18 fluorodeoxyglucose CT, it constitutes the current imaging of choice for MM. This article illustrates the progress of the MRI technique over the past three decades and situates its role in the management of patients with MM.

In the process of X-ray transmission imaging, the mutual occlusion between structures will lead to the image information overlap, and the computed tomography (CT) method is often required to obtain the structure information at different depths, but with low efficiency. To address these problems, an X-ray focused on imaging algorithm based on multi-line scanning is proposed, which only requires the scene target to pass through the detection area along a straight line to extract multi-view information, and uses the optical field reconstruction theory to achieve the de-obscured reconstruction of the structure at a specified depth with high real-time. The results of multi-line scan and X-ray reconstruction of the target show that the proposed method can reconstruct the information of any specified depth layer, and it can perform fast imaging detection of the mutually occluded target structures and improve the recognition of the occluded targets, which has a good application prospect.

In recent years, ghost imaging has made important progress in the field of remote sensing imaging. In order to promote the application of solar ghost imaging in this field, this paper studies the computational ghost imaging based on the incoherent light of blackbody radiation. Firstly, according to the intensity probability density function of blackbody radiation, the expression of contrast-to-noise ratio (R_CN) describing the quality of computational ghost imaging is obtained, and then the random speckle pattern simulating blackbody radiation is generated by computer with the idea of slice sampling, finally, a digital light projector is used to modulate and generate the random modulated light that simulates the blackbody radiation light source, and this light source is used to realize the computational ghost image of the reflective object in the experiment. The “ghost image” of the object under different measurement frame numbers is reconstructed, and the contrast-to-noise ratio describing the imaging quality is measured. The results show that the image quality is relatively good when the average intensity (gray) of the randomly modulated speckle is about 160. On the other hand, the contrast-to-noise ratio of the image gradually increases from 0.8795 to 1.241, 1.516, 1.755, 2.100 and 2.371 as the number of measurement frames increases from 2,000 to 4,000, 6,000, 8,000, 12,000 and 20,000, respectively. The experimental results are basically consistent with the theoretical analysis. The results are of great significance for the application of ghost imaging with incoherent light, such as sunlight, which is approximately regarded as blackbody radiation, in the field of remote imaging.

Based on the characteristics of liquid lens sparse aperture imaging, a radiative multiplet array structure is proposed; a simplified model of sparse aperture imaging is given, and the analytical expression of the modulation transfer function is derived from the optical pupil function of the multiplet array structure; the specific distribution form of this multiplet array structure is given, and the structure parameters are approximated by the dimensionless method; the two types of radiative multiplet array structures are discussed, and the filling factor, redundancy, modulation transfer function and other characteristic parameters are calculated. The physical phenomena exhibited by the parametric scan are discussed, and the structural features and imaging characteristics of these two arrays are compared. The results show that the type-II structure with larger actual equivalent aperture and actual cutoff frequency and lower redundancy is selected when the average modulation transfer function and the IF characteristics of the modulation transfer function of the two structures are close to each other; the type-II structure has certain advantages in imaging; the conclusion is suitable for arbitrary enclosing circle size because the liquid lens-based multiplet array structure adopts dimensionless approximation parameters; compared with the composite toroidal structure, the radiative multiplet mirror structure has a larger actual cut-off frequency and actual equivalent aperture when the filling factor is the same.

Objective: To evaluate the imaging features of spondyloarthritis on magnetic resonance imaging (MRI) of the sacroiliac (SI) joints in terms of topography (in thirds) and affected margin, since this aspect is rarely addressed in the literature. Methods: Cross-sectional study with MRI (1.5 T) evaluation of the SI in 16 patients with diagnosis of axial spondyloarthritis regarding the presence of acute (subchondral bone edema, enthesitis, synovitis and capsulitis) and chronic changes (erosions, subchondral bone sclerosis, bone bridging and fatty replacement), performed by two radiologists, blinded to clinical data. MRI findings were correlated with clinical data including age, disease duration, medications, HLA-B27, BASDAI, ASDAS-VHS and ASDAS-PCR, BASMI, BASFI, and mSASSS. Results: Bone edema pattern and erosions showed predominance in the upper third of SI (p = 0.050, p = 0.0014, respectively). There was a correlation between the time of disease and structural changes by affected third (p = 0.028-0.037), as well as the presence of bone bridges with BASMI (p = 0.028) and mSASSS (p = 0.014). Patients with osteitis of the lower third had higher ASDAS values (ESRV: p = 0.011 and CRP: p = 0.017). Conclusion: Chronic inflammatory changes and the pattern of bone edema predominated in the upper third of the SI, but there was also concomitant involvement of the middle or lower thirds of the joint. The localization of involvement in the upper third of the SI was insufficient to differentiate between degeneration and inflammation.