scholarly journals Intracranial Lesion Detection and Artifact Characterization: Comparative Study of Susceptibility and T2*-Weighted Imaging in Dogs and Cats

2021 ◽  
Vol 8 ◽  
Author(s):  
Nadja Wolfer ◽  
Adriano Wang-Leandro ◽  
Katrin M. Beckmann ◽  
Henning Richter ◽  
Matthias Dennler
Keyword(s):  
Frontal Sinus ◽  
Image Interpretation ◽  
Lesion Detection ◽  
Limiting Factor ◽  
Susceptibility Weighted Imaging ◽  
Hounsfield Units ◽  
Blinded Observer ◽  
Correct Assignment ◽  
Phase Images ◽  
Signal Void

Susceptibility-weighted imaging (SWI), an MRI sequence for the detection of hemorrhage, allows differentiation of paramagnetic and diamagnetic substances based on tissue magnetic susceptibility differences. The three aims of this retrospective study included a comparison of the number of areas of signal void (ASV) between SWI and T2*-weighted imaging (T2*WI), differentiation of hemorrhage and calcification, and investigation of image deterioration by artifacts. Two hundred twelve brain MRIs, 160 dogs and 52 cats, were included. The sequences were randomized and evaluated for presence/absence and numbers of ASV and extent of artifacts causing image deterioration by a single, blinded observer. In cases with a CT scan differentiation of paramagnetic (hemorrhagic) and diamagnetic (calcification) lesions was made, SWI was performed to test correct assignment using the Hounsfield Units. Non-parametric tests were performed to compare both sequences regarding detection of ASV and the effect of artifacts on image quality. The presence of ASV was found in 37 SWI sequences and 34 T2*WI sequences with a significant increase in ASV only in dogs >5 and ≤ 15 kg in SWI. The remaining weight categories showed no significance. CT examination was available in 11 cases in which 81 ASV were found. With the use of phase images, 77 were classified as paramagnetic and none as diamagnetic. A classification was not possible in four cases. At the level of the frontal sinus, significantly more severe artifacts occurred in cats and dogs (dogs, p < 0.001; cats, p = 0.001) in SWI. The frontal sinus artifact was significantly less severe in brachycephalic than non-brachycephalic dogs in both sequences (SWI, p < 0.001; T2*WI, p < 0.001). In conclusion, with the advantages of better detection of ASV in SWI compared with T2*WI and the opportunity to differentiate between paramagnetic and diamagnetic origin in most cases, SWI is generally recommended for dogs. Frontal sinus conformation appears to be a limiting factor in image interpretation.

MRI-visible perivascular spaces in basal ganglia but not centrum semiovale or hippocampus were related to deep medullary veins changes

2021 ◽  
pp. 0271678X2110381
Author(s):  
Kemeng Zhang ◽  
Ying Zhou ◽  
Wenhua Zhang ◽  
Qingqing Li ◽  
Jianzhong Sun ◽  
...  
Keyword(s):  
Basal Ganglia ◽  
Small Vessel Disease ◽  
Cerebral Small Vessel Disease ◽  
Susceptibility Weighted Imaging ◽  
Perivascular Spaces ◽  
Centrum Semiovale ◽  
Vessel Disease ◽  
Phase Images ◽  
Deep Medullary Veins

Our purpose is to assess the role of deep medullary veins (DMVs) in pathogenesis of MRI-visible perivascular spaces (PVS) in patients with cerebral small vessel disease (cSVD). Consecutive patients recruited in the CIRCLE study (ClinicalTrials.gov ID: NCT03542734) were included. Susceptibility Weighted Imaging-Phase images were used to evaluate DMVs based on a brain region-based visual score. T2 weighted images were used to evaluate PVS based on the five-point score, and PVS in basal ganglia (BG-PVS), centrum semiovale (CSO-PVS) and hippocampus (H-PVS) were evaluated separately. 270 patients were included. The severity of BG-PVS, CSO-PVS and H-PVS was positively related to the increment of age (all p < 0.05). The severity of BG-PVS and H-PVS was positively related to DMVs score (both p < 0.05). Patients with more severe BG-PVS had higher Fazekas scores in both periventricle and deep white matter (both p < 0.001) and higher frequency of hypertension ( p = 0.008). Patients with more severe H-PVS had higher frequency of diabetes ( p < 0.001). Besides, high DMVs score was an independent risk factor for more severe BG-PVS ( β = 0.204, p = 0.001). Our results suggested that DMVs disruption might be involved in the pathogenesis of BG-PVS.

Case 17.17

2014 ◽  
pp. 821-822
Author(s):  
Christine U. Lee ◽  
James F. Glockner
Keyword(s):  
Arterial Phase ◽  
Portal Venous Phase ◽  
Phase Images ◽  
Signal Void ◽  
Venous Phase

58-year-old woman with cirrhosis Axial precontrast (Figure 17.17.1) and arterial phase (Figure 17.17.2) and portal venous phase (Figure 17.17.3) postgadolinium water and fat images from a 3D SPGR Dixon acquisition. Notice that the phase and frequency directions have been swapped on the arterial phase acquisition and that there is a large geographic signal void in the middle of the liver on the water image, with the missing anatomy appearing on the corresponding fat image. All artifacts have been corrected on the portal venous phase images....

Susceptibility-weighted imaging: Are they really corrected phase images?

2010 ◽  
Vol 31 (5) ◽  
pp. 1282-1282
Author(s):  
Jun Zhang ◽  
Jianhong Wang ◽  
Ke Li ◽  
Weijun Tang ◽  
Daoying Geng
Keyword(s):  
Susceptibility Weighted Imaging ◽  
Phase Images

scholarly journals Susceptibility weighted imaging: differentiating between calcification and hemosiderin

2015 ◽  
Vol 48 (2) ◽  
pp. 93-100 ◽  
Author(s):  
Jeam Haroldo Oliveira Barbosa ◽  
Antonio Carlos Santos ◽  
Carlos Ernesto Garrido Salmon
Keyword(s):  
Computed Tomography ◽  
Susceptibility Weighted Imaging ◽  
Diagnostic Reliability ◽  
Computed Tomography Images ◽  
Hyperintense Signal ◽  
Phase Images ◽  
Echo Time ◽  
Images Processing ◽  
Age Range ◽  
Hemosiderin Deposits

Objective:To present a detailed explanation on the processing of magnetic susceptibility weighted imaging (SWI), demonstrating the effects of echo time and sensitive mask on the differentiation between calcification and hemosiderin.Materials and Methods:Computed tomography and magnetic resonance (magnitude and phase) images of six patients (age range 41– 54 years; four men) were retrospectively selected. The SWI images processing was performed using the Matlab’s own routine.Results:Four out of the six patients showed calcifications at computed tomography images and their SWI images demonstrated hyperintense signal at the calcification regions. The other patients did not show any calcifications at computed tomography, and SWI revealed the presence of hemosiderin deposits with hypointense signal.Conclusion:The selection of echo time and of the mask may change all the information on SWI images, and compromise the diagnostic reliability. Amongst the possible masks, the authors highlight that the sigmoid mask allows for contrasting calcifications and hemosiderin on a single SWI image.

Single-image phase retrieval for hard X-ray grating interferometry

2019 ◽  
Vol 26 (1) ◽  
pp. 215-219
Author(s):  
Zhili Wang ◽  
Kun Ren ◽  
Xiaomin Shi ◽  
Yuqi Ren ◽  
Kun Gao ◽  
...  
Keyword(s):  
Phase Retrieval ◽  
Complex Refractive Index ◽  
Image Interpretation ◽  
Phase Image ◽  
Image Method ◽  
Single Image ◽  
Homogeneous Sample ◽  
X Ray ◽  
Phase Images

A single-image method is proposed for quantitative phase retrieval in hard X-ray grating interferometry. This novel method assumes a quasi-homogeneous sample, with a constant ratio between the real and imaginary parts of its complex refractive index. The method is first theoretically derived and presented, and then validated by synchrotron radiation experiments. Compared with the phase-stepping method, the presented approach abandons grating scanning and multiple image acquisition, and is therefore advantageous in terms of its simplified acquisition procedure and reduced data-collection times, which are especially important for applications such as in vivo imaging and phase tomography. Moreover, the sample's phase image, instead of its first derivative, is directly retrieved. In particular, the stripe artifacts encountered in the integrated phase images are significantly suppressed. The improved quality of the retrieved phase images can be beneficial for image interpretation and subsequent processing. Owing to its requirement for a single image and its robustness against noise, the present method is expected to find use in potential investigations in diverse applications.

Utilizing Dark Field Electron Microscopy to Produce Lantern Slides

1974 ◽  
Vol 32 ◽  
pp. 116-117
Author(s):  
J. N. Meador ◽  
C. N. Sun ◽  
H. J. White
Keyword(s):  
Electron Microscope ◽  
Electron Micrographs ◽  
Dark Field ◽  
Limiting Factor ◽  
Clinical Laboratories ◽  
Field Electron ◽  
Time Element ◽  
Field Electron Microscopy ◽  
Dark Field Electron ◽  
Dark Field Micrographs

The electron microscope is being utilized more and more in clinical laboratories for pathologic diagnosis. One of the major problems in the utilization of the electron microscope for diagnostic purposes is the time element involved. Recent experimentation with rapid embedding has shown that this long phase of the process can be greatly shortened. In rush cases the making of projection slides can be eliminated by taking dark field electron micrographs which show up as a positive ready for use. The major limiting factor for use of dark field micrographs is resolution. However, for conference purposes electron micrographs are usually taken at 2.500X to 8.000X. At these low magnifications the resolution obtained is quite acceptable.

Observation of biological macromolecules using various electron microscopic methods

1978 ◽  
Vol 36 (2) ◽  
pp. 170-171
Author(s):  
Mitsuo Ohtsuki ◽  
Michael Sogard
Keyword(s):  
Electron Microscope ◽  
Phase Contrast ◽  
Image Interpretation ◽  
Density Lipoprotein ◽  
Biological Macromolecules ◽  
Contrast Effects ◽  
Biological Structure ◽  
Electron Microscopic ◽  
Structural Investigations ◽  
Staining Techniques

Structural investigations of biological macromolecules commonly employ CTEM with negative staining techniques. Difficulties in valid image interpretation arise, however, due to problems such as variability in thickness and degree of penetration of the staining agent, noise from the supporting film, and artifacts from defocus phase contrast effects. In order to determine the effects of these variables on biological structure, as seen by the electron microscope, negative stained macromolecules of high density lipoprotein-3 (HDL3) from human serum were analyzed with both CTEM and STEM, and results were then compared with CTEM micrographs of freeze-etched HDL3. In addition, we altered the structure of this molecule by digesting away its phospholipid component with phospholipase A2 and look for consistent changes in structure.

Simulated Dark-Field Electron Micrographs of Point Defects and Organometallics

1975 ◽  
Vol 33 ◽  
pp. 200-201
Author(s):  
William Krakow
Keyword(s):  
Electron Micrographs ◽  
Point Defects ◽  
Structure Determination ◽  
Atomic Structure ◽  
Image Interpretation ◽  
Dark Field ◽  
Field Electron ◽  
Dark Field Microscopy ◽  
Dark Field Electron

Tilted beam dark-field microscopy has been applied to atomic structure determination in perfect crystals, several synthesized molecules with heavy atcm markers and in the study of displaced atoms in crystals. Interpretation of this information in terms of atom positions and atom correlations is not straightforward. Therefore, calculated dark-field images can be an invaluable aid in image interpretation.

Toward High-Resolution Low-Voltage SEM

1988 ◽  
Vol 46 ◽  
pp. 218-219
Author(s):  
Zhifeng Shao
Keyword(s):  
Low Voltage ◽  
Spherical Aberration ◽  
Chromatic Aberration ◽  
Limiting Factor ◽  
Operating Voltage ◽  
Probe Radius ◽  
Non Local ◽  
Electron Microscopes ◽  
Image Position ◽  
Scanning Electron Microscopes

Recently, low voltage (≤5kV) scanning electron microscopes have become popular because of their unprecedented advantages, such as minimized charging effects and smaller specimen damage, etc. Perhaps the most important advantage of LVSEM is that they may be able to provide ultrahigh resolution since the interaction volume decreases when electron energy is reduced. It is obvious that no matter how low the operating voltage is, the resolution is always poorer than the probe radius. To achieve 10Å resolution at 5kV (including non-local effects), we would require a probe radius of 5∽6 Å. At low voltages, we can no longer ignore the effects of chromatic aberration because of the increased ratio δV/V. The 3rd order spherical aberration is another major limiting factor. The optimized aperture should be calculated as

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