Comparison of ESWAN, SWI-SPGR, and 2D T2*-Weighted GRE Sequence for Depicting Cerebral Microbleeds

Neuroimaging of Mild Traumatic Injury

Traumatic brain injury (TBI) is a global public health problem and is a leading cause of disability, morbidity and death in children and adults in USA It is characterised by alteration of neurological, behavioral and cognitive function as consequence of biomechanical insulte and possible progression to chronic encephalopathy. According to the CDC, approximately 75% of all reported TBIs are considered mild in form. Mild TBI is defined as individuals who had head trauma with subsequent mild deficit on the GCS and thu are frequently observed in military combat, athletes and motor vehicle accidents. Clinical assessment of mTBI is difficult and therefore different neuroimaging techniques have been used to characterized different stages of the disease. This article reviews the utility of imaging while focusing on the emerging applications of advanced MRI studies and PET in TBI.

Gender heterogeneity in the influencing factors for cerebral microbleeds in acute ischemic stroke patients

BACKGROUND

Cerebral microbleeds (CMBs) are common in acute ischemic stroke (AIS) patients. The presence of CMBs increases the risk of hemorrhagic transformation in AIS patients, and it is also closely associated with cognitive decline and even dementia. At present, there exist different opinions on the independent risk factors for CMBs, and there is no consensus on whether there are gender differences in -post-stroke CMB. Therefore, this study sought to investigate gender heterogeneity in the influencing factors for CMBs by studying male and female AIS patients.

METHODS

This was a China-based, Single-center, retrospective review of data from 482 AIS inpatients at the Neurology Department of Hebei General Hospital (NCT05882123). Both demographic and clinical data were collected from the study subjects. Different head magnetic resonance imaging sequences were used to assess the subjects' CMBs, white matter lesions, and old lacunar infarcts (LI). Various statistical methods, including the t-test, χ2 test, and logistic regression, were used to analyze the gender heterogeneity of the influencing factors for CMBs in AIS patients.

RESULTS

When compared with the male AIS patients, the female AIS patients were older and had higher total cholesterol, triglyceride, high-density lipoprotein, low-density lipoprotein, ApoA, ApoB, and fibrinogen levels. The female AIS patients also had higher National Institute of Health Stroke Scale scores and hypertension disease composition ratios. By contrast, the proportions of female AIS patients with a history of smoking and a history of alcohol consumption were both lower than the corresponding proportions of male AIS patients. These differences were all statistically significant (p < .05). There were no statistically significant differences in the incidence and severity of CMBs between the male and female AIS patients (χ2 ＝ 0.851, 3.092, p > .05). The univariate and multivariate stepwise logistic regression analyses confirmed that age (OR = 1.074, 95% CI: 1.013-1.139, p = .016) and old LI (OR = 4.295, 95% CI: 1.062-17.375, p = .041) were independent risk factors for comorbid CMBs in the female AIS patients, while blood glucose (OR = 0.692, 95% CI: 0.494-0.968, p = .031) was an independent protective factor for comorbid CMBs in the female AIS patients. However, these factors were not found to be independent risk or protective factors for comorbid CMBs in male AIS patients.

CONCLUSION

There are gender differences in the influencing factors for CMBs in AIS patients. Age, old LIs, and blood glucose are independent risk or protective factors for comorbid CMBs in female AIS patients, although they are not associated with the risk of developing CMBs in male AIS patients.

Cerebral Amyloid Angiopathy

Cerebral amyloid angiopathy (CAA) is associated with deposition of amyloid proteins within the intracranial vessels. It is most frequently sporadic and risk increases with advancing age. Amyloid deposition is associated with increased risk of peripheral microhemorrhage, lobar hemorrhage, and/or repetitive subarachnoid hemorrhage. The presence of a peripherally located lobar hemorrhage on computed tomography in an elderly patient should raise concern for underlying CAA, as should multiple foci of peripheral susceptibility artifact or superficial siderosis on susceptibility-weighted imaging, the most sensitive modality for these findings. Newer PET radiotracers are also useful in detecting amyloid deposition.

Quantitative susceptibility mapping as an imaging biomarker for Alzheimer’s disease: The expectations and limitations

Alzheimer’s disease (AD) is the most common type of dementia and a distressing diagnosis for individuals and caregivers. Researchers and clinical trials have mainly focused on β-amyloid plaques, which are hypothesized to be one of the most important factors for neurodegeneration in AD. Meanwhile, recent clinicopathological and radiological studies have shown closer associations of tau pathology rather than β-amyloid pathology with the onset and progression of Alzheimer’s symptoms. Toward a biological definition of biomarker-based research framework for AD, the 2018 National Institute on Aging–Alzheimer’s Association working group has updated the ATN classification system for stratifying disease status in accordance with relevant pathological biomarker profiles, such as cerebral β-amyloid deposition, hyperphosphorylated tau, and neurodegeneration. In addition, altered iron metabolism has been considered to interact with abnormal proteins related to AD pathology thorough generating oxidative stress, as some prior histochemical and histopathological studies supported this iron-mediated pathomechanism. Quantitative susceptibility mapping (QSM) has recently become more popular as a non-invasive magnetic resonance technique to quantify local tissue susceptibility with high spatial resolution, which is sensitive to the presence of iron. The association of cerebral susceptibility values with other pathological biomarkers for AD has been investigated using various QSM techniques; however, direct evidence of these associations remains elusive. In this review, we first briefly describe the principles of QSM. Second, we focus on a large variety of QSM applications, ranging from common applications, such as cerebral iron deposition, to more recent applications, such as the assessment of impaired myelination, quantification of venous oxygen saturation, and measurement of blood– brain barrier function in clinical settings for AD. Third, we mention the relationships among QSM, established biomarkers, and cognitive performance in AD. Finally, we discuss the role of QSM as an imaging biomarker as well as the expectations and limitations of clinically useful diagnostic and therapeutic implications for AD.

Prognosis and Diagnostic Biomarkers of Mild Traumatic Brain Injury: Current Status and Future Prospects

Mild traumatic brain injury (mTBI) is the most prevalent type of TBI (80-90%). It is characterized by a loss consciousness for less than 30 minutes, post-traumatic amnesia for less than 24 hours, and Glasgow Coma Score of 13-15. Accurately diagnosing mTBIs can be a challenge because the majority of these injuries do not show noticeable or visible changes on neuroimaging studies. Appropriate determination of mTBI is tremendously important because it might lead in some cases to post-concussion syndrome, cognitive impairments including attention, memory, and speed of information processing problems. The scientists have studied different methods to improve mTBI diagnosis and enhanced approaches that would accurately determine the severity of the trauma. The present review focuses on discussing the role of biomarkers as potential key factors in diagnosing mTBI. The present review focuses on 1) protein based peripheral and CNS markers, 2) genetic biomarkers, 3) imaging biomarkers, 4) neurophysiological biomarkers, and 5) the studies and clinical trials in mTBI. Each section provides information and characteristics on different biomarkers for mTBI.

MRI of healthy brain aging: A review

We present a review of the characterization of healthy brain aging using MRI with an emphasis on morphology, lesions, and quantitative MR parameters. A scope review found 6612 articles encompassing the keywords "Brain Aging" and "Magnetic Resonance"; papers involving functional MRI or not involving imaging of healthy human brain aging were discarded, leaving 2246 articles. We first consider some of the biogerontological mechanisms of aging, and the consequences of aging in terms of cognition and onset of disease. Morphological changes with aging are reviewed for the whole brain, cerebral cortex, white matter, subcortical gray matter, and other individual structures. In general, volume and cortical thickness decline with age, beginning in mid-life. Prevalent silent lesions such as white matter hyperintensities, microbleeds, and lacunar infarcts are also observed with increasing frequency. The literature regarding quantitative MR parameter changes includes T₁ , T₂ , T₂ *, magnetic susceptibility, spectroscopy, magnetization transfer, diffusion, and blood flow. We summarize the findings on how each of these parameters varies with aging. Finally, we examine how the aforementioned techniques have been used for age prediction. While relatively large in scope, we present a comprehensive review that should provide the reader with sound understanding of what MRI has been able to tell us about how the healthy brain ages.

Distinct pattern of microsusceptibility changes on brain magnetic resonance imaging (MRI) in critically ill patients on mechanical ventilation/oxygenation

Purpose

Over the years, interesting SWI abnormalities in patients from intensive care units (ICU) were observed, not attributable to a specific cause and with uncertain clinical significance. Recently, multiple SWI-hypointense foci were mentioned related to neurological complications of SARS-COV-2 infection. The purpose of the study was to describe the patterns of susceptibility brain changes in critically-ill patients who underwent mechanical ventilation and/or extracorporeal membrane oxygenation (ECMO).

Methods

An institutional board-approved, retrospective study was conducted on 250 ICU patients in whom brain MRI was performed between January 2011 and May 2020. Out of 48 patients who underwent mechanical ventilation/ECMO, in fifteen patients (median age 47.7 years), the presence of SWI abnormalities was observed and described.

Results

Microsusceptibilities were located in white-gray matter interface, in subcortical white matter (U-fibers), and surrounding subcortical nuclei in 13/14 (92,8%) patients. In 8/14 (57,1%) patients, SWI foci were seen infratentorially. The corpus callosum was affected in ten (71,4%), internal capsule in five (35,7%), and midbrain/pons in six (42,8%) patients.

Conclusion

We showed distinct patterns of diffuse brain SWI susceptibilities in critically-ill patients who underwent mechanical ventilation/ECMO. The etiology of these foci remains uncertain, but the association with mechanical ventilation, prolonged respiratory failure, and hypoxemia seems probable explanations.

Role of a modified ultrafast MRI brain protocol in clinical paediatric neuroimaging

AIM

To establish a role for modified ultrafast magnetic resonance imaging (MRI) of the brain in clinical paediatric patients based on clinically acceptable image quality and diagnostic accuracy.

MATERIALS AND METHODS

A prospective study was conducted with institutional review board approval on an ultrafast MRI brain protocol consisting of sagittal T1-weighted, axial T2-weighted, axial fluid-attenuated inversion recovery (FLAIR), axial diffusion-weighted imaging (DWI), and axial T2∗-weighted sequences. Preliminary investigations revealed that the default ultrafast T2-weighted sequence was prone to pulsation artefacts. A modified ultrafast T2-weighted sequence was therefore developed to replace the default ultrafast T2-weighted sequence. Thirty-five patients with clinical indication for neuroimaging underwent ultrafast MRI, modified ultrafast T2-weighted sequence and standard MRI at 3 T. Image quality of ultrafast MRI sequences were graded as clinically "diagnostic" or "non-diagnostic" and compared against the corresponding standard MRI sequences as the reference standard. The modified ultrafast T2-weighted sequence surpassed the default ultrafast T2-weighted sequence in image quality. The ultrafast MRI protocol was therefore replaced with the modified ultrafast T2-weighted sequence creating a modified ultrafast MRI protocol. The clinical reports of modified ultrafast MRI were compared against standard MRI for diagnostic concordance, categorised further as "normal", "clinically significant", or "clinically minor" abnormalities.

RESULTS

Ultrafast T1-weighted, FLAIR, and DWI sequences had comparable image quality to standard MRI sequences. The ultrafast T2∗-weighted sequence had significantly higher non-diagnostic images (42.9%) compared to the standard MRI sequence (2.9%). The default ultrafast T2-weighted sequence had significantly higher non-diagnostic images compared to the modified ultrafast T2-weighted sequence and standard T2-weighted sequence (82.9%, 5.7%, 8.6%, respectively). There was 100% concordance for normal and clinically significant abnormalities and 23% discordance for clinically minor abnormalities. Modified ultrafast MRI takes 5 minutes 41 seconds compared to standard MRI time of 14 minutes 57 seconds.

CONCLUSION

The modified ultrafast MRI protocol for brain imaging demonstrates clinically acceptable image quality in four out of five sequences and has high accuracy in diagnosing normal and clinically significant abnormalities when compared against the standard MRI protocol for brain imaging. It could potentially benefit a select group of paediatric patients who require neuroimaging.

Wave-CAIPI susceptibility-weighted imaging achieves diagnostic performance comparable to conventional susceptibility-weighted imaging in half the scan time

OBJECTIVES

We aimed to evaluate the agreement in the detection of cerebral microbleeds (CMBs) between conventional susceptibility-weighted imaging (SWI) and fast SWI using wave-controlled aliasing in parallel imaging (CAIPI) acceleration. We also scrutinized the diagnostic agreement for intracranial lesions and compared the image quality between both sequences.

METHODS

Institutional review board approval was obtained and informed consent was waived for this retrospective study. We included 181 consecutive patients who had undergone brain MRI with both conventional SWI (scan time, 251 s) and wave-CAIPI SWI (scan time, 113 s) from September 2017 to November 2017. All images were independently reviewed by two radiologists for the detection and counting of CMBs using the Microbleed Anatomical Rating Scale (MARS). One neuroradiologist diagnosed intracranial lesions and scored image quality using visual analysis. The agreement for detection of CMBs and intracranial lesions was calculated, and interobserver agreements were analyzed by using kappa and intraclass correlation.

RESULTS

For detection of CMBs, both the conventional and wave-CAIPI SWI showed significantly high agreement of 100% for the presence of CMBs, and 94.5% using MARS. Wave-CAIPI SWI achieved more than 97% agreement of MARS when divided by anatomical locations, with excellent agreement. Interobserver agreements were also excellent. The diagnosis for intracranial lesions (33 lesions in 28 patients) demonstrated 100% agreement. The image quality of both sequences is not significantly different (p = 0.20).

CONCLUSIONS

Wave-CAIPI SWI achieved high agreement for CMB detection and diagnosis of intracranial lesions compared to conventional SWI within half of the scan time.

KEY POINTS

• Wave-CAIPI SWI achieves a diagnostic performance for the detection of cerebral microbleeds that is comparable to that of conventional SWI in half the scan time. • Interobserver agreement for the detection (presence vs. absence) and counting of cerebral microbleeds of wave-CAIPI SWI was excellent. • Wave-CAIPI SWI demonstrated a 100% agreement for the diagnosis of intracranial lesions and comparable image quality compared to conventional SWI.

The enhanced T2 star weighted angiography (ESWAN) value for differentiating borderline from malignant epithelial ovarian tumors

PURPOSE

To investigate the potential of ESWAN in differentiating borderline epithelial ovarian tumors (BEOTs) from malignant epithelial ovarian tumors (MEOTs).

METHOD

Thirty-four patients with 37 lesions were enrolled, including 14 BEOTs and 23 MEOTs. The magnitude, phase, R₂* and T₂* maps were analyzed by two observers. The regions of interest were drawn along the boundaries of tumors on the slice with maximal solid area, according to fat suppression T₂WI and T₁WI. The consistency among the three measurements taken by two observers was tested by intra-class correlation coefficients. Agreement of average values measured by two observers was evaluated by Bland-Altman plots. All the data of BEOTs and MEOTs were compared using the independent-sample t test. The receiver operating characteristic curve was used to evaluate the diagnostic performance.

RESULTS

No statistical differences were observed in the magnitude and phase values between two tumor groups. The R₂* value of BEOTs was lower than that of MEOTs (P < 0.001), whereas the T₂* value of BEOTs was higher than that of MEOTs (P = 0.01). The area under the curve of R₂* values was 0.894 and the corresponding cutoff value was 7.50 Hz, with the sensitivity, specificity and accuracy of 85.7%, 82.6% and 86.5%, respectively. The AUC of T₂* values was 0.776 and the corresponding cutoff value was 143.73 ms with the sensitivity, specificity and accuracy of 71.4%, 82.6% and 78.4%, respectively.

CONCLUSIONS

R₂* and T₂* values can be used for quantificationally differentiating BEOTs from MEOTs and the R₂* has better diagnostic performance.

Deep cerebral microbleeds are associated with the severity of lacunar infarcts and hypertension: A retrospective analysis

Cerebral microbleeds (CMBs) and lacunar infarcts are common manifestations of cerebral small vessel disease. However, the association between the location of CMBs and lacunar infarcts is unclear. Our study aimed to clarify the relationship between the location of CMBs and lacunar infarcts.This study retrospectively analyzed 166 patients with ischemic stroke or transient ischemic attacks admitted in the Geriatric Neurology Department of Chinese PLA General Hospital between February 2010 and December 2012. We collected clinical characteristics and risk factors of CMBs. The location of CMBs on T2*-weighted angiography was assessed by the Microbleed Anatomical Rating Scale. The number of lacunar infarcts and the severity of white matter hyperintensities were also recorded. The association between the location of CMBs and lacunar infarcts parameters was examined.CMBs were present in 77 (46.4%) patients. The presence [odds ratios (OR), 2.14; 95% confidence interval (CI), 1.02-4.48], number (OR, 1.17; 95% CI, 1.02-1.36 per lesion), severity (OR, 1.61; 95% CI, 1.07-2.42) of lacunar infarcts, and hypertension (OR, 5.76; 95% CI, 2.01-16.55) were independent risk factors for CMBs. Stratified by the location of CMBs, lobar CMBs and infratentorial CMBs did not show significant association with lacunar infarcts. Deep CMBs were significantly associated with the number (OR 1.18, 95% CI 1.03-1.36) and severity (OR 1.71, 95% CI 1.11-2.63) of lacunar infarcts. Moreover, the percentage of deep CMBs increased with the increased severity of lacunar infarcts (P = .003).Deep CMBs rather than lobar and infratentorial CMBs are associated with lacunar infarcts.

Assessment of cerebral microbleeds by susceptibility-weighted imaging at 3T in patients with end-stage organ failure

PURPOSE

Cerebral microbleeds (CMBs) are small rounded lesions representing cerebral hemosiderin deposits surrounded by macrophages that results from previous microhemorrhages. The aim of this study was to review the distribution of cerebral microbleeds in patients with end-stage organ failure and their association with specific end-stage organ failure risk factors.

MATERIALS AND METHODS

Between August 2015 and June 2017, we evaluated 15 patients, 9 males, and 6 females, (mean age 65.5 years). Patients population was subdivided into three groups according to the organ failure: (a) chronic kidney failure (n = 8), (b) restrictive cardiomyopathy undergoing heart transplantation (n = 1), and (c) end-stage liver failure undergoing liver transplantation (n = 6). The MR exams were performed on a 3T MR unit and the SWI sequence was used for the detection of CMBs. CMBs were subdivided in supratentorial lobar distributed, supratentorial non-lobar distributed, and infratentorial distributed.

RESULTS

A total of 91 microbleeds were observed in 15 patients. Fifty-nine CMBs lesions (64.8%) had supratentorial lobar distribution, 17 CMBs lesions (18.8%) had supratentorial non-lobar distribution and the remaining 15 CMBs lesions (16.4%) were infratentorial distributed. An overall predominance of supratentorial multiple lobar localizations was found in all types of end-stage organ failure. The presence of CMBs was significantly correlated with age, hypertension, and specific end-stage organ failure risk factors (p < 0.001).

CONCLUSIONS

CMBs are mostly founded in supratentorial lobar localization in end-stage organ failure. The improved detection of CMBs with SWI sequences may contribute to a more accurate identification of patients with cerebral risk factors to prevent complications during or after the organ transplantation.

Cerebral Microbleeds Remain for Nine Years: A Prospective Study with Yearly Magnetic Resonance Imaging

BACKGROUND

Cerebral microbleeds (CMBs) are refined neuroimaging findings detected on T2*-weighted gradient echo (GRE) magnetic resonance imaging (MRI) and are widely accepted as an important marker of the vulnerability of cerebral small vessels. It is necessary to further clarify the natural history of CMBs by a longitudinal study. This study aimed to reveal the natural history of CMBs and find a better way to track CMBs by a prospective long-term observation.

METHODS

We performed yearly brain MRI assessments for 7 or more years in 8 nonvalvular atrial fibrillation Japanese outpatients with CMBs detected in the baseline MRI. We began to use a 3.0T MRI scanner from 2012 as well.

RESULTS

We followed up 3 patients for 9 years, 2 for 8 years, and 3 for 7 years. In all patients, the CMBs at baseline did not disappear during the follow-up period. Importantly, the CMB in 1 patient seemed to disappear during the sixth imaging using 1.5T T2*-weighted GRE but was detected again during the seventh imaging with 3.0T susceptibility weighted imaging and ninth imaging with 3.0T T2* GRE. Moreover, in a patient implanted with a pacemaker, which is only applicable for 1.5T MRI at present, the CMB seemed to disappear and appeared once again with a 1.5T T2*-weighted GRE at a slice thickness of 2.5 mm instead of 5 mm.

CONCLUSIONS

From this prospective study, we obtained 2 absolutely new findings that CMBs remained for as long as 9 years and a high-field or thin-slice MRI can detect concealed CMBs.

Assessment of cerebral microbleeds by susceptibility-weighted imaging in Alzheimer's disease patients: A neuroimaging biomarker of the disease

Purpose The objective of this study was to correlate the presence and distribution of cerebral microbleeds in Alzheimer's disease patients with cerebrospinal fluid biomarkers (amyloid-beta and phosphorylated tau 181 protein levels) and cognitive decline by using susceptibility-weighted imaging magnetic resonance sequences at 1.5 T. Material and methods Fifty-four consecutive Alzheimer's disease patients underwent brain magnetic resonance imaging at 1.5 T to assess the presence and distribution of cerebral microbleeds on susceptibility-weighted imaging images. The images were analyzed in consensus by two neuroradiologists, each with at least 10 years' experience. Dementia severity was assessed with the Mini-Mental State Examination score. A multiple regression analysis was performed to assess the associations between the number and location of cerebral microbleed lesions with the age, sex, duration of the disease, cerebrospinal fluid amyloid-beta and phosphorylated tau 181 protein levels, and cognitive functions. Results A total of 296 microbleeds were observed in 54 patients; 38 patients (70.4%) had lobar distribution, 13 patients (24.1%) had non-lobar distribution, and the remaining three patients (5.6%) had mixed distribution, demonstrating that Alzheimer's disease patients present mainly a lobar distribution of cerebral microbleeds. The age and the duration of the disease were correlated with the number of lobar cerebral microbleeds ( P < 0.001). Cerebrospinal fluid amyloid-beta, phosphorylated tau 181 protein levels, and cognitive decline were correlated with the number of lobar cerebral microbleeds in Alzheimer's disease patients ( P < 0.001). Conclusion Lobar distribution of cerebral microbleeds is associated with Alzheimer's disease and the number of lobar cerebral microbleeds directly correlates with cerebrospinal fluid amyloid-beta and phosphorylated tau 181 protein levels and with the cognitive decline of Alzheimer's disease patients.

Deep microbleeds and periventricular white matter disintegrity are independent predictors of attention/executive dysfunction in non-dementia patients with small vessel disease

BACKGROUND

Cerebral small vessel disease (SVD) is the common cause of cognitive decline in the old population. MRI can be used to clarify its mechanisms. However, the surrogate markers of MRI for early cognitive impairment in SVD remain uncertain to date. We investigated the cognitive impacts of cerebral microbleeds (CMBs), diffusion tensor imaging (DTI), and brain volumetric measurements in a cohort of post-stroke non-dementia SVD patients.

METHODS

Fifty five non-dementia SVD patients were consecutively recruited and categorized into two groups as no cognitive impairment (NCI) (n = 23) or vascular mild cognitive impairment (VaMCI) (n = 32). Detailed neuropsychological assessment and multimodal MRI were completed.

RESULTS

The two groups differed significantly on Z scores of all cognitive domains (all p < 0.01) except for the language. There were more patients with hypertension (p = 0.038) or depression (p = 0.019) in the VaMCI than those in the NCI group. Multiple regression analysis of cognition showed periventricular mean diffusivity (MD) (β = -0.457, p < 0.01) and deep CMBs numbers (β = -0.352, p < 0.01) as the predictors of attention/executive function, which explained 45.2% of the total variance. Periventricular MD was the independent predictor for either memory (β = -0.314, p < 0.05) or visuo-spatial function (β = -0.375, p < 0.01); however, only small proportion of variance could be accounted for (9.8% and 12.4%, respectively). Language was not found to be correlated with any of the MRI parameters. No correlation was found between brain atrophic indices and any of the cognitive measures.

CONCLUSION

Arteriosclerotic CMBs and periventricular white matter disintegrity seem to be independent MRI surrogated markers in the early stage of cognitive impairment in SVD.

Susceptibility-weighted imaging: current status and future directions

Susceptibility-weighted imaging (SWI) is a method that uses the intrinsic nature of local magnetic fields to enhance image contrast in order to improve the visibility of various susceptibility sources and to facilitate diagnostic interpretation. It is also the precursor to the concept of the use of phase for quantitative susceptibility mapping (QSM). Nowadays, SWI has become a widely used clinical tool to image deoxyhemoglobin in veins, iron deposition in the brain, hemorrhages, microbleeds and calcification. In this article, we review the basics of SWI, including data acquisition, data reconstruction and post-processing. In particular, the source of cusp artifacts in phase images is investigated in detail and an improved multi-channel phase data combination algorithm is provided. In addition, we show a few clinical applications of SWI for the imaging of stroke, traumatic brain injury, carotid vessel wall, siderotic nodules in cirrhotic liver, prostate cancer, prostatic calcification, spinal cord injury and intervertebral disc degeneration. As the clinical applications of SWI continue to expand both in and outside the brain, the improvement of SWI in conjunction with QSM is an important future direction of this technology. Copyright © 2016 John Wiley & Sons, Ltd.

The Presence of Previous Cerebral Microbleeds Has a Negative Effect on Hypertensive Intracerebral Hemorrhage Recovery

Background and Purpose: Cerebral microbleeds are an intracerebral microangiopathy with bleeding tendency found in intracerebral hemorrhage patients. However, studies about cerebral microbleed effects on the prognosis of hypertensive intracerebral hemorrhage patients are rare. We performed a prospective study to discuss not only the risk factors of cerebral microbleed incidence in hypertensive intracerebral hemorrhage patients but also the relevance of cerebral microbleeds with silent brain infarction, hemorrhage and prognosis.

Methods: This study enrolled 100 patients diagnosed with hypertensive intracerebral hemorrhage within 3 days after onset. Magnetic resonance imaging including susceptibility-weighted imaging and diffusion-weighted imaging (DWI) were utilized to examine patients on the fifth day after onset. Regular follow-ups were performed to examine the following clinical cerebrovascular events and vascular deaths in 1 year.

Results: Cerebral microbleeds were observed in 55 (55%) patients. Multiple logistic regression analysis showed that over-aging, elevation of serum creatinine, and leukoaraiosis were independently associated with cerebral microbleeds. In addition, higher silent brain infarction prevalence was observed in patients with cerebral microbleeds. In contrast, none of the cerebral microbleed patients exhibited cerebral microbleeds ≥5, which is an independent risk factor of poor 3-month neurological function recovery. During the 1-year follow-up, 14 subjects presented clinical cerebrovascular events or vascular death. The Cox proportional hazards model implicated that atrial fibrillation, cerebral microbleeds ≥5 and silent brain infarction were independent predictive factors for these events.

Conclusions: Over-aging combined with an elevation of serum creatinine and leukoaraiosis were independent risk factors of cerebral microbleeds. Patients with cerebral microbleeds were more likely to exhibit silent brain infarction. Poor recovery of 3-month neurological function was observed in hypertensive intracerebral hemorrhage patients with cerebral microbleeds ≥5. Cerebral microbleeds ≥5 or silent brain infarction might also indicate an elevated risk of future cerebrovascular events and vascular death.

The risk factors and pattern of cerebral microbleeds in Parkinson's disease

BACKGROUND AND PURPOSE

Cerebral microbleeds (CMBs) in Parkinson's disease (PD) have been reported recently and concerned increasingly. Our aim was to investigate the risk factors and pattern of CMBs in patients with PD, as well as the influence of risk factors on the pattern of CMBs.

METHODS

We retrospectively collected medical and imaging data of 247 patients who underwent brain susceptibility-weighted imaging. Logistic regression analyses were performed to determine the risk factors of CMBs. The frequency and amount of CMBs in different locations between patients with and without risk factors were analyzed.

RESULTS

Of the 247 patients with PD, 39 (15.79%) had CMBs, 27 (69.23%) had lobar CMBs, 20 (51.28%) had deep CMBs and 17 (43.59%) had infratentorial CMBs. A history of cerebral ischemic events was independently associated with the presence of CMBs (odds ratio (OR) 4.485 [95% CI 2.150-9.356]; p = 0.000), especially with lobar and deep CMBs. Hypertension and Hoehn and Yahr score were also associated with the presence of deep CMBs. Only white matter hyperintensities were independently associated with the presence of infratentorial CMBs. Compared to patients without risk factors, the frequency of deep CMBs was greater in those with a history of cerebral ischemic events (p = 0.013), while the amount of deep CMBs was higher in those with hypertension (p = 0.035).

CONCLUSION

CMBs in PD seem to present a lobe-dominant pattern. A history of cerebral ischemic events and hypertension may be two strong risk factors which preferentially influences the pattern of deep CMBs in PD.

Evaluating the Role of Reduced Oxygen Saturation and Vascular Damage in Traumatic Brain Injury Using Magnetic Resonance Perfusion-Weighted Imaging and Susceptibility-Weighted Imaging and Mapping

The cerebral vasculature, along with neurons and axons, is vulnerable to biomechanical insult during traumatic brain injury (TBI). Trauma-induced vascular injury is still an underinvestigated area in TBI research. Cerebral blood flow and metabolism could be important future treatment targets in neural critical care. Magnetic resonance imaging offers a number of key methods to probe vascular injury and its relationship with traumatic hemorrhage, perfusion deficits, venous blood oxygen saturation changes, and resultant tissue damage. They make it possible to image the hemodynamics of the brain, monitor regional damage, and potentially show changes induced in the brain's function not only acutely but also longitudinally following treatment. These methods have recently been used to show that even mild TBI (mTBI) subjects can have vascular abnormalities, and thus they provide a major step forward in better diagnosing mTBI patients.

Reproducibility and variability of quantitative magnetic resonance imaging markers in cerebral small vessel disease

Brain imaging is essential for the diagnosis and characterization of cerebral small vessel disease. Several magnetic resonance imaging markers have therefore emerged, providing new information on the diagnosis, progression, and mechanisms of small vessel disease. Yet, the reproducibility of these small vessel disease markers has received little attention despite being widely used in cross-sectional and longitudinal studies. This review focuses on the main small vessel disease-related markers on magnetic resonance imaging including: white matter hyperintensities, lacunes, dilated perivascular spaces, microbleeds, and brain volume. The aim is to summarize, for each marker, what is currently known about: (1) its reproducibility in studies with a scan-rescan procedure either in single or multicenter settings; (2) the acquisition-related sources of variability; and, (3) the techniques used to minimize this variability. Based on the results, we discuss technical and other challenges that need to be overcome in order for these markers to be reliably used as outcome measures in future clinical trials. We also highlight the key points that need to be considered when designing multicenter magnetic resonance imaging studies of small vessel disease.

Reduced white matter integrity in amateur boxers

INTRODUCTION

Professional boxing can lead to chronic traumatic encephalopathy, a variant of traumatic brain injury (TBI). Its occurrence in amateur boxers is a matter of debate since amateur boxing is considered to be less harmful due to more strict regulations. However, several studies using different methodological approaches have revealed subtle signs of TBI even in amateurs. Diffusion tensor imaging (DTI) is sensitive to microscopic white matter changes and has been proven useful in TBI when routine MR imaging often is unrevealing.

METHODS

DTI, with tract-based spatial statistics (TBSS) together with neuropsychological examination of executive functions and memory, was used to investigate a collective of 31 male amateur boxers and 31 age-matched controls as well as a subgroup of 19 individuals, respectively, who were additionally matched for intellectual performance (IQ).

RESULTS

All participants had normal findings in neurological examination and conventional MR. Amateur boxers did not show deficits in neuropsychological tests when their IQ was taken into account. Fractional anisotropy was significantly reduced, while diffusivity measures were increased along central white matter tracts in the boxers group. These changes were in part associated with the number of fights.

CONCLUSIONS

TBSS revealed widespread white matter disturbance partially related to the individual fighting history in amateur boxers. These findings closely resemble those in patients with accidental TBI and indicate similar histological changes in amateur boxers.

Frequency and appearance of hemosiderin depositions after aneurysmal subarachnoid hemorrhage treated by endovascular therapy

INTRODUCTION

It is still unclear how often subarachnoid hemorrhage (SAH) leads to chronic hemosiderin depositions. In this study, we aimed to determine the frequency of chronic hemosiderin depositions after aneurysmal SAH in patients who did not undergo surgery. Furthermore, we analyzed typical MRI patterns of chronic SAH and sought to obtain information on the temporal course of MRI signal changes.

METHODS

We retrospectively analyzed 90 patients who had undergone endovascular treatment for acute aneurysmal SAH. In all patients, initial CT studies and at least one T2*-weighted MRI obtained 6 months or later after SAH were analyzed for the presence and anatomical distribution of SAH or chronic hemosiderin depositions. In total, 185 T2*-weighted MRI studies obtained between 2 days and 148 months after SAH were evaluated (mean follow-up 30.2 months).

RESULTS

On MRI studies obtained later than 6 months after SAH, subpial hemosiderin depositions were found in 50 patients (55.5%). Most frequent localizations were the parenchyma adjacent to the frontal and parietal sulci and the insular cisterns. While the appearance of hemosiderin depositions was dynamic within the first 3 months, no changes were found during subsequent follow-up. MR signal changes were not only conclusive with subarachnoid hemosiderin depositions but in many cases also resembled those that have been associated with cortical hemosiderosis.

CONCLUSIONS

T2*-weighted MRI is an effective means of diagnosing prior SAH. Our study suggests that chronic hemosiderin depositions can be found in a considerable number of patients after a single event of subarachnoid hemorrhage.

Improving detection of siderotic nodules in patients with liver disease using 2D ESWAN technique

RATIONALE AND OBJECTIVES

To conduct a preliminary evaluation of the use of two-dimensional (2D) enhanced multiecho T2*-weighted angiography (ESWAN) sequence for detection and quantification of siderotic nodules (SNs) in patients with liver disease.

MATERIALS AND METHODS

Seventy-four patients with liver cirrhosis SNs confirmed by pathology were imaged using conventional T1-weighted imaging (T1WI), T2-weighted imaging (T2WI), T2*-weighted imaging (T2*WI), and 2D ESWAN. The signal intensity ratio (SIR) and the lesion-to-liver contrast-to-noise ratio (CNR) were calculated. The quality of SNs identification of the ESWAN images was evaluated.

RESULTS

The SIR of SNs on ESWAN was lower than those in any other sequence, whereas the CNR of SNs on ESWAN was significantly greater than those in the other sequences (P < .05). The conspicuity of SNs was shown to be significantly different between every pair of techniques (P < .05). The nodules had the better conspicuity in ESWAN images than in the T1WI, T2WI, and T2*WI. Almost all (97.3%, 72 of 74) patients were considered to have excellent grade 3 conspicuity on ESWAN imaging, compared to 40.5% (30 of 74) for T2*WI. The signal intensity of small hepatic cancer on ESWAN was greater than those of SNs.

CONCLUSIONS

The detection and conspicuity of SNs is substantially improved using breath-hold 2D ESWAN. Therefore, 2D ESWAN imaging may be an alternative for the accurate detection of hepatic SNs in the future.

Utility of R2* obtained from T2*-weighted imaging in differentiating hepatocellular carcinomas from cavernous hemangiomas of the liver

Purpose

To evaluate the feasibility of applying R₂* values to differentiate hepatocellular carcinomas (HCC) from cavernous hemangiomas of the liver (CHL).

Materials and Methods

This retrospective study was approved by the participating Institutional Review Board and written informed consent for all subjects were obtained. Seventy-three patients with 79 pathologically identified HCCs and 65 patients with 91 clinically or pathologically identified CHLs were enrolled in this study. All subjects underwent a breath-hold multi-echo T₂* weighted MR imaging on a 1.5T clinical MR scanner. R₂* values from HCC and CHL groups were compared using the Mann-Whitney non-parametric U test. A cut-off value of R₂* was evaluated with receiver operator characteristic (ROC) analysis.

Results

The mean R₂* value was 23.32±12.23 Hz (95% confidence interval [CI]: 20.58 Hz, 26.06 Hz) for the HCC group, and 3.66±2.37 Hz (95% CI: 3.17 Hz, 4.15 Hz) for the CHL group. The mean R₂* value for HCC was significantly higher than that of CHL (p<0.001). A threshold of 9.48 Hz for the minimum R₂* value in the diagnosis of HCC resulted in a sensitivity of 96.20% (76 out of 79 patients), and a specificity of 97.80% (89 out of 91 patients). The positive predictive value (PPV), negative predictive value (NPV) and diagnostic accuracy for HCC were 97.44% (76 out of 78 patients), 96.74% (89 out of 92 patients) and 97.06% (165 out of 170 patients), respectively. The AUC for differentiation between these two groups was 0.994 (95% CI: 0.980, 1.000).

Conclusions

R₂* is a significant MRI biomarker to differentiate HCC from CHL with satisfying sensitivity and specificity.

Quantification of Phase Values of Cerebral Microbleeds in Hypertensive Patients Using ESWAN MRI

PURPOSE

The presence of cerebral microbleeds (CMBs) may have predictive and diagnostic value for cerebrovascular diseases. The purpose of our study was to measure the phase values (PVs) of CMBs by phase maps.

METHODS

We retrospectively analyzed 75 patients with hypertension who had CMBs using enhanced T2*-weighted angiography (ESWAN). The PVs of CMBs were measured and documented. The mean PVs of CMBs were correlated with demographic features and the grade of white matter lesions for seven brain regions.

RESULTS

A total of 275 CMBs were found. Their mean PV was - 1.39 ± 0.29 radians. The mean PV of CMBs in seven brain regions was significantly lower than that of red nucleus and substantia nigra of healthy controls (P <  .05). The mean PV of CMBs in the basal ganglia gray matter was significantly lower than that of the brainstem, subcortical white matter, and cerebellum (P < 0.05). In subcortical white matter, the PVs were significantly lower in patients with hypertension < 10 years than for those patients with hypertension ≥ 10 years (P < 0.05). In basal ganglia gray matter, the PVs were significantly lower in men than in women (P < 0.05). There was no significant correlation between the PVs of CMBs and the demographic features addressed or the grade of white matter lesions.

CONCLUSIONS

Measurement of the PV of phase maps using ESWAN sequence provides quantitative information for detection of CMBs. The measurement data reported herein will provide a reference for a longitudinal study of CMBs in the future.