Susceptibility weighted imaging in the evaluation of hemorrhagic diffuse axonal injury

Diffuse axonal injury（DAI）is axonal and small vessel injury produced by a sudden acceleration of the head by an external force,and is a major cause of death and severe disability（Paterakis et al.,2000）.Prognosis is poorer in patients with apparent hemorrhage than in those without（Paterakis et al.,2000）.Therefore,it is important to identify the presence and precise position of hemorrhagic foci for a more accurate diagnosis.CT and magnetic resonance imaging（MRI）have long been applied in the diagnosis of DAI, but they are not sensitive enough for the detection of small hemorrhagic foci, and cannot meet the requirements for early diagnosis. A major advance in MRI has been the development of susceptibility weighted imaging （SWI）, which has greatly increased the ability to detect small hemorrhagic foci after DAI （Ashwal et al., 2006）.

The Clinical Application Value of Susceptibility Weighted Imaging in the Central Nervous System

Susceptibility weighted imaging(SWI)is a relatively new magnetic resonance imaging(MRI)technique that uses the difference in tissue magnetic susceptibility to image,and has unique value compared to traditional magnetic resonance imaging.This article summarizes its application in the central nervous system and provides a reference for imaging diagnosis and clinical treatment.

Magnetic resonance susceptibility weighted imaging in detecting intracranial calcification and hemorrhage

Background Computed tomography （CT） is better than routine magnetic resonance imaging （MRI） in detecting intracranial calcification. This study aimed to assess the value of MR susceptibility weighted imaging （SWI） in the detection and differentiation of intracranial calcification and hemorrhage. Methods Enrolled in this study were 35 patients including 13 cases of calcification demonstrated by CT and 22 cases of intracerebral hemorrhage. MR sequences used in all the subjects included axial T1WI, T2WI and SWI. The phase shift （PS） of calcification and hemorrhage on SWI was calculated and their signal features on corrected phase images were compared. The sensitivity of T1WI, T2WI and SWI in detecting intracranial calcification and hemorrhage was analyzed statistically. Results The detection rate of SWI for cranial calcification was 98.2%, significantly higher than that of T1WI and T2WI. It was not significantly different from that of CT （P 〉0.05）. There were 49 hemorrhagic lesions at different stages detected on SWI, 30 on T2WI and 18 on T1WI. The average PS of calcification and hemorrhage was ＋0.734±0.073 and -0.112±0.032 respectively （P 〈0.05）. The PS of calcification was positive and presented as a high signal or the mixed signal dominated by a high signal on the corrected phase images, whereas the PS of hemorrhage was negative and presented as a low signal or the mixed signal dominated by a low signal.Conclusions SWI can accurately demonstrate intracranial calcification, not dependant on CT. Being more sensitive than routine MRI in detecting micro-hemorrhage, SWI may play an important role in differentiating cerebral diseases associated with calcification or hemorrhage.

Detection of siderotic nodules in the liver with susceptibility weighted imaging： correlations to serum ferritin, Child-Pugh grade and hyaluronic acid levels

Background Chronic liver disease causes aberrant formation of fibrous tissue that impedes normal liver function, ultimately resulting in liver cirrhosis. Iron uptake can occur within the hepatic parenchyma or within the various nodules that form in a cirrhotic liver, termed siderotic nodules （SN）. We aimed to investigate the diagnostic performance of susceptibility weighted imaging （SWI） for detection of SN in patients with liver cirrhosis, and to evaluate the potential of SN numbers for assessing the degree of hepatic iron deposition, liver function, and liver fibrosis stage. Methods Ninety-one patients with chronic liver cirrhosis, who underwent megnetic resonance imagine （MRI） scanning in our department between November 2010 and April 2011, were included in the study. A 3.0T MRI scanner was used to acquire T1WI, T2WI, T2＊WI, and SWI images. The number of nodules, signal intensity ratio （SIR）, and contrast noise ratio （CNR） were recorded and analyzed by chi-square and ANOVA statistical tests. Correlation analysis was performed to evaluate the correlations between the number of SN and Child-Pugh classification, ferritin and hyaluronic acid levels. Results The sensitivity of SWI, T1WI, T2WI, and T2＊WI for detecting SN was 62.5%, 12.1%, 24.2% and 41.8%, respectively. SWI detected significantly more nodules than routine T1WI, T2WI, and T2＊WI procedures （P 〈0.05）. The SIR was the lowest in SWI （0.361±0.209）, as compared to T1WI （0.852±0.163）, T2WI （0.584±0.172）, and T2＊WI （0.497±0.196）. The CNR was the highest in SWI （13.932±5.637）, as compared to T1WI （9.147±5.785）, T2WI （9.771±5.490）, and T2＊WI （11.491±4.573）. The correlation coefficients of the number of SN with ferritin, Child-Pugh classification, and hyaluronic acid levels were 0.672, -0.055, and 0.163, respectively. Conclusions The sensitivity and contrast of SWI for detecting SN in patients with liver cirrhosis are higher than conventional MRI. The number of SN can help to assess the degree of iron deposition in patients with liver cirrhosis.

Susceptibility-Weighted MRI in the Evaluation of Gynecologic Diseases

Introduction: Owing to the advanced development of MRI science, it causes obvious great changes of many diseases that affect the female genital system and affect their fertility. Hemorrhagic gynecological diseases especially endometriosis affect young females and cause cyclic pain, in addition to infertility. So early detection is essential for proper treatment. Susceptibility-weighted (SWI) as one of the most recent newly created MRI sequences is highly sensitive to detect products of hemorrhage within different gynecologic disorders with 94.7% sensitivity being more meticulous than conventional MRI sequences as T1 and T2. Aim of the Work: A comparison between T1 and T2 as conventional MRI sequences with susceptibility-weighted images (SWI) in many gynecologic disorders by the detection of the presence of internal products of hemorrhage at any stage. Subjects and Methods: 48 consecutive patients from Benha University clinics (age range, 17 - 60 years;mean age, 35.67 years). The patients included in the study were presenting with pelvic pain, irregular menses, Dyspareunia, and swelling. All with suspicious diagnosis of ovarian and extra-ovarian lesions. 38 patients out of the 48 patients were known to contain hemorrhagic disorder;all the patients underwent MRI routine pelvis protocol adding SWI sequence. Results: There was a greatly significant difference between SWI and conventional MRI sequences T1and T2 with sensitivity 94.7%, 57.9% and 33.3% respectively. Conclusion: SWI is a promising tool in the evaluation of hemorrhagic foci within different gynecological disorders. The great ability of detecting hemosiderin foci increases the value of SWI over conventional MRI or US.

Diffuse axonal injury after traumatic cerebral microbleeds: an evaluation of imaging techniques

Previous neuropathological studies regarding traumatic brain injury have primarily focused on changes in large structures, for example, the clinical prognosis after cerebral contusion, intrace- rebral hematoma, and epidural and subdural hematoma. In fact, many smaller injuries can also lead to severe neurological disorders. For example, cerebral microbleeds result in the dysfunc- tion of adjacent neurons and the disassociation between cortex and subcortical structures. These tiny changes cannot be adequately visualized on CT or conventional MRI. In contrast, gradient echo sequence-based susceptibility-weighted imaging is very sensitive to blood metabolites and microbleeds, and can be used to evaluate traumatic cerebral microbleeds with high sensitivity and accuracy. Cerebral microbleed can be considered as an important imaging marker for dif- fuse axonal injury with potential relevance for prognosis. For this reason, based on experimental and clinical studies, this study reviews the role of imaging data showing traumatic cerebral microbleeds in the evaluation of cerebral neuronal injury and neurofunctional loss.

Elevated Pulse Pressure Is a Risk Factor for Cerebral Microbleeds. A Single Center Case-Control Study

Recent developments in brain magnetic resonance imaging using advanced Susceptibility Weighted Imaging (SWI) have significantly increased the detection and prevalence of Cerebral Microbleeds (CMBs). Here, we aimed to explore the association between Pulse Pressure (PP) and CMBs. Having been implicated in various arteriopathies, we hypothesized that elevated PP could also be a risk for CMBs. A retrospective case-control study was conducted from August 2021 to September 2022 at Zhongnan Hospital of Wuhan University China. Extracted data were analyzed in SPSS. Chi-square test, binary logistic regression, and Spearman’s correlation analysis were conducted.104 patients were analyzed. Univariate analysis showed no significant association between PP and CMBs, OR 1.65 (95% CI: 0.737 - 3.694;p > 0.05), while DBP and alcohol consumption were significant, ORs 2.956 (95% CI: 1.249 - 6.997, p < 0.05) and 2.525 (95% CI: 1.062 - 6.002, p < 0.05) respectively. Multivariate analysis, showed that PP was significantly associated with CMBs, OR 3.194 (95% CI: 1.024 - 9.964, p < 0.05) in combination with SBP, DBP, gender, age, smoking and alcohol consumption. Taken together, the study showed that elevated PP is associated with CMB, but is not an independent risk factor for CMBs.

Comparative Study of DSC-PWI and 3D-ASL in Ischemic Stroke Patients

Summary： The purpose of this study was to quantitatively analyze the relationship between three di- mensional arterial spin labeling （3D-ASL） and dynamic susceptibility contrast-enhanced perfusion weighted imaging （DSC-PWI） in ischemic stroke patients. Thirty patients with ischemic stroke were in- cluded in this study. All subjects underwent routine magnetic resonance imaging scanning, diffusion weighted imaging （DWI）, magnetic resonance angiography （MRA）, 3D-ASL and DSC-PWI on a 3.0T MR scanner. Regions of interest （ROIs） were drawn on the cerebral blood flow （CBF） maps （derived from ASL） and multi-parametric DSC perfusion maps, and then, the absolute and relative values of ASL-CBF, DSC-derived CBF, and DSC-derived mean transit time （MTT） were calculated. The rela- tionships between ASL and DSC parameters were analyzed using Pearson＇s correlation analysis. Re- ceiver operative characteristic （ROC） curves were performed to define the thresholds of relative value of ASL-CBF （rASL） that could best predict DSC-CBF reduction and MTT prolongation. Relative ASL better correlated with CBF and MTT in the anterior circulation with the Pearson correlation coefficients （R） values being 0.611 （P〈0.001） and-0.610 （P〈0.001） respectively. ROC curves demonstrated that when rASL 〈0.585, the sensitivity, specificity and accuracy for predicting ROIs with rCBF〈0.9 were 92.3%, 63.6% and 76.6% respectively. When rASL 〈0.952, the sensitivity, specificity and accuracy for predicting ROIs rMTT〉I.0 were 75.7%, 89.2% and 87.8% respectively. ASL-CBF map has better linear correlations with DSC-derived parameters （DSC-CBF and MTT） in anterior circulation in ischemic stroke patients. Additionally, when rASL is lower than 0.585, it could predict DSC-CBF decrease with moderate accuracy. IfrASL values range from 0.585 to 0.952, we just speculate the prolonged MTT.

Differentiation of white and red thrombus with magnetic resonance imaging： a phantom study

Background An early identification of the composition of arterial thrombus may have diagnostic, therapeutic, and prognostic implications. The variation of magnetic resonance （MR） signal intensity between white and red thrombi, especially in the susceptibility sensitive MR sequence, remains unknown. Our research was to evaluate the feasibility of MRI in differentiating of white and red thrombi with a phantom study. Methods A total of 12 red and 12 white thrombi were prepared with the venous blood. Examination of the phantom was completed using a 3.0T MR unit, including fluid attenuated inversion recovery （FLAIR） T1, T2-weighted imaging （T2WI）, FLAIR T2, T2＊ gradient echo （T2＊GRE） imaging, and susceptibility weighted angiography sequences （SWAN）. MR signal intensity patterns of the thrombi were objectively classified as hyperintensity, isointensity and hypointensity, compared with the background agar. The volume of thrombus was calculated and correlated with its signal intensity. Results For white thrombi, 11/12 clots showed hyperintensity and 1/12 showed isointensity in FLAIR T1 images. In T2WI, 6/12 clots showed hyperintensity, 3/12 isointensity, and 3/12 hypointensity. In FLAIR T2, 8/12 clots showed hyperintensity and 4/12 showed isointensity. In T2＊GRE, 3/12 clots showed hyperintensity and the remaining 9/12 clots showed isointensity. In SWAN, 5/12 clots demonstrated hyperintensity and 7/12 isointensity. For the red thrombus, 12/12 clots demonstrated hyperintensity in FLAIR T1, T2WI, and FLAIR T2 sequences. In T2＊GRE and SWAN sequences, 3/12 clots displayed hypointensity and the remaining 9/12 clots showed slight hyperintensity. Thrombi with hypointensity displayed in T2＊GRE and SWAN sequences were significantly larger than those with hyperintensity. Conclusions Differentiation of white and red thrombi with conventional MR sequence is unreliable, because both kinds of thrombi do not possess unique signal intensity features in these sequences. Red thrombus may or may not show hypointensity in the susceptibility sensitive MR sequences, depending on its size and time course.

Magnetic resonance study of the structure and function of the hippocampus and amygdala in patients with depression

Background The hippocampus and amygdala exhibit structural and functional alterations in patients with depression. The objective of this study was to investigate the structural and functional relationships between these core regions. Methods Based on the severity of their condition, 60 patients and 20 healthy controls were equally divided into four groups （mild group, moderate group, major group and health controls group）, scanned by T1-MR, functional magnetic resonance imaging （fMRI）, and susceptibility weighted imaging （SWI）. Structural image, BOLD image, and SWI image were collected for processing and analysis. The characteristics of the depression and controls were checked by analysis of variance test, and the difference between groups was checked by Dunnett＇s test. Results The volume of hippocampus and amygdala varied with the severity of the condition. The signal obtained under the stimulation of negative events was linearly decreased in the mild, moderate and major groups revealed by fMRI. The length and diameter of the lateral ventricle vein was reduced in the mild group, whereas the number of branches increased. In the moderate and major groups, the reduction in the length, diameter and increase in the number of branches of the lateral ventricle vein were greater. Conclusion The alterations of the volume, fMRI, and cerebral veins in these core regions may account for the causal relationship between structure and function.