Regions Of Interest In Patients Research Articles

Intraoperative Frozen Section via Neurosafe During Robotic Radical Prostatectomy in the Era of Preoperative Risk Stratifications and Primary Staging With mpMRI and PSMA-PET CT: Is There a Perfect Candidate?

We aimed to analyze the effect of preoperative risk assessment including Ga-68 PSMA PET and multiparametric magnetic resonance imaging (mpMRI) on nerve sparing practices, positive surgical margin (PSM) rates and oncological outcomes based on a comparison between patients underwent RARP with and without Neurosafe (NS). Patients underwent RARP with NS (RARP-NS) or without (RARP-only) NS retrospectively evaluated. Suspicion for extracapsular extension on mpMRI and/or Ga-68 PSMA PET was recorded as i(imaging)T3. NS was performed according to the Martini-Klinik technique. PSM at preserved bundle side were called PSM at region of interest (ROI) while the others were elsewhere. A total of 208 patients (90 in RARP-NS, 118 in RARP-only groups) were included. Preoperatively the RARP-only group showed significantly higher mean PSA (p=.01) and PIRADS 5 (p=.002) findings and had more D'Amico high risk (DAHR) patients (p=.08). The overall PSM rates for pT2 versus pT3 disease were 7.5% versus 21.6 and 15.6% versus 55% in RARP-NS and RARP-only groups, respectively. NS resulted in more bilaterally preserved bundles (81.1% vs. 66.3%) and less PSM at the ROI (3.3% vs. 23.4%) than RARP-only group. NS outperformed RARP-only in all clinical settings had its highest differential benefit in more bilateral nerve sparing and less PSM at ROI in patients with both DAHR and iT3 disease. BCR rates were 2.2% and 2.5% for RARP-NS and RARP only groups, respectively (p=.4). One patient in RARP-NS and 9 in RARP-only groups had PSA persistence (p=.02). RARP-NS led to more preserved bundles with less PSM. It was especially useful in DAHR patients with preoperative extracapsular extension suspicion in imaging simultaneously.

Perioperative functional imaging after extracranial carotid endarterectomy for the detection of cerebral hyperperfusion syndrome

IntroductionSyngoDynaPBVNeuro® is a tool to perform cerebral blood volume (CBV) measurements intraoperatively by functional imaging producing CT-like images. Aim of this prospective study was to analyze the clinical relevance and benefit of CBV measurement with regard to neurological complications like cerebral hyperfusion syndrome (CHS).MethodsForty-five patients undergoing endarterectomy (CEA) of the internal carotid artery were included; functional imaging with CBV measurement was performed before and after CEA. To evaluate and analyze CBV, six regions of interest (ROI) were identified for all patients with an additional ROI in patients with symptomatic ICA stenosis and previous stroke. The primary endpoint of the study was a perioperative change in CBV measurements. Secondary outcomes were incidence of stroke, TIA, CHS, and perioperative morbidity and mortality.ResultsThirty-day stroke incidence and thirty-day mortality were 0%. Thirty-day morbidity was 6.7%. Two patients from the asymptomatic group suffered from transient neurological symptoms without signs of intracerebral infarction in CT or MR scan, meeting diagnostic criteria for CHS. In 83.3% of ROIs in these patients, an increase of blood volume was detected. Overall, 26.7% patients suffered from unilateral headache as expression of potential CHS. A total of 69.4% of ROIs in patients with postoperative unilateral headache showed an increase when comparing pre- and postoperative CBV measurements.ConclusionThe results show that increased CBV measured by functional imaging is a possible surrogate marker of neurological complications like CHS after CEA. By using intraoperative CBV measurement, the risk of CHS can be estimated early and appropriate therapeutic measures can be applied.

Comparison of region-of-interest delineation methods for diffusion tensor imaging in patients with cervical spondylotic radiculopathy

BackgroundDiffusion tensor imaging is a promising technique for determining the responsible lesion of cervical radiculopathy, but the selection and delineation of the region of interest (ROI) affect the results. This study explored the impact of different ROI sketching methods on the repeatability and consistency of DTI measurement values in patients with cervical spondylotic radiculopathy (CSR).MethodsThis retrospective study included CSR patients who underwent DTI imaging. The images were analyzed independently by two radiologists. Four delineation methods were used: freehand method, maximum roundness, quadrilateral method, and multi-point averaging method. They re-examined the images 6 weeks later. The intra-class correlation coefficient (ICC) was used to investigate the consistency between the two measurements and the reproducibility between two radiologists.ResultsForty-two CSR patients were included in this study. The distribution of the compressed nerve roots was five C4, eight C5, sixteen C6, eleven C7, and two C8. No differences were found among the four methods in fractional anisotropy (FA) or apparent diffusion coefficient (ADC), irrespective of radiologists (all P>0.05). Similar results were observed between the first and second measurements (all P>0.05), but some significant differences were observed for radiologist 2 for the four-small rounds method (P=0.033). The freehand and single largest circle methods were the two methods with the highest ICC between the two measurements and the two radiologists (all ICC >0.90).ConclusionThe freehand and single largest circle methods were the most consistent methods for delineating DTI ROI in patients with CSR.

Functional dysconnectivity of cerebellum and attention networks in emotional dysregulation shared between attention deficit hyperactivity disorder and major depressive disorder: a multimodal imaging study.

Emotional dysregulation (ED) is a common characteristic of both attention deficit hyperactivity disorder (ADHD) and major depressive disorder (MDD), especially in adolescents. However, whether ADHD and MDD may share the specific ED-related neural networks remains unknown. In total, 43 adolescents with clinical ED (22 adolescents with ADHD and 21 with MDD) were recruited; in addition, 29 sex- and age-matched healthy controls (HCs) were included. Resting-state functional connectivity (RSFC) analysis, voxel-based morphometry, and diffusion tensor imaging analysis were performed for each patient. In addition, we determined the significant regions of interest in patients with ED due to ADHD and MDD as compared with HCs and tested their correlations with clinical rating scale scores. Compared with HCs, patients with ED had greater RSFC in the cerebellum and supramarginal gyrus (SMG), especially between vermis VI and the SMG in the attention networks, and lower RSFC between the right supplementary motor area and right lateral parietal area. Lower gray matter (GM) volume in the SMG was also found. RSFC was significantly correlated with clinical rating scale scores for all patients with ED due to ADHD or MDD. GM change was correlated with ED and MDD rating scale scores. The cerebellum and attention networks might play major roles in ED pathophysiology in adolescents with ADHD and MDD. Increased connectivity of the vermis to the SMG serves as a possible underlying neural network.

Repeatability of quantitative MRI in patients with rheumatoid arthritis

IntroductionRheumatoid arthritis (RA) affects 1% of the population and is principally associated with joint inflammation. It is suggested however that muscle involvement may be one of the earliest clinical features of RA. It is therefore important that techniques exist to accurately assess muscle health in those with RA to enable successful treatment. This study assesses the inter-rater and intra-rater repeatability of Diffusion Tensor MRI (DTI), 2-Point Dixon fat fraction, and T2 relaxation of the thigh muscle in patients with RA using manual regions of interest (ROI). MethodsNineteen patients (10/19 males; mean age 59; range 18–85) diagnosed with RA had an MRI scan of their hamstrings and quadriceps muscles to obtain fat fraction (FF), mean diffusivity (MD), fractional anisotropy (FA), and T2 quantitative measurements. Two raters DB & MF independently contoured ROIs for each patient. DB repeated the ROI for the same 19 patients after a 6-month hiatus to assess intra-rater repeatability. Inter-rater and intra-rater repeatability for the ROI measurements were compared using Inter Class Correlation (ICC) and Bland–Altman plots. ResultsThere was excellent agreement for both inter-rater and intra-rater repeatability. ICC results ranged from 0.900 to 0.998 (P < 0.001), and intra-rater ICC results ranged from 0.977 to 0.999 (P < 0.001). Bland–Altman plots also showed excellent agreement. ConclusionsICC measurements and Bland–Altman plots showed excellent repeatability and agreement with no statistically significant differences when assessing the inter-rater and intra-rater repeatability of FF, MD, FA, and T2 relaxation of the thigh muscle using manual regions of interest in patients with RA. Implications for practiceManual ROI drawing does not introduce significant errors obtaining FF, MD, FA, and T2 MRI measurements in an RA population.

Serial MRI studies over 12\u2009months using manual and atlas-based region of interest in patients with amyotrophic lateral sclerosis

BackgroundAmyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by loss of upper and lower motor neurons. There is a need for an imaging biomarker to track disease progression. Previously, magnetic resonance imaging (MRI) has shown loss of grey and white matter in the brain of patients with ALS compared to controls. We performed serial diffusion tractography imaging (DTI) study of patients with ALS looking for changes over time.MethodsOn all subjects (n = 15), we performed three MRI studies at 6 month intervals. DTI changes were assessed with tract-based spatial statistics (TBSS) and region of interest (ROI) studies. Cortic-spinal tract (CST) was selected for our ROI at the upper level; the posterior limb of internal capsule (PLIC), and a lower level in the pons.ResultsThere was no significant change in DTI measures over 12 months of observation. Better correlation of manual and atlas-based ROI methods was found in the posterior limb of the internal capsule than the pons.ConclusionWhile previous DTI studies showed significant differences between ALS subjects and controls, within individual subjects there is little evidence of progression over 12 months. This suggests that DTI is not a suitable biomarker to assess disease progression in ALS.

Is bone mineral density lower in the necrotic lesion in pre-collapse osteonecrosis of the femoral head?

The purpose of this study was to clarify whether bone mineral density (BMD) of the necrotic lesion in precollapse osteonecrosis of the femoral head (ONFH) is reduced according to Hounsfield unit (HU) values on computed tomography (CT). The superior one-third of the femoral head in the coronal section was set as the region of interest (ROI) for the measurement of HU values. First, HU values of 101 control participants were assessed to identify relevant confounding factors. Next, the relationship between HU values and BMD on dual-energy X-ray absorptiometry (DXA) was verified. Then the mean HU value of the ROI in patients with pre-collapse ONFH was compared with that in propensity score-matched control participants. Finally, the HU values of the lateral boundary in the patients with and without subsequent collapse were compared. Multivariable analysis showed that both age and BMI were significantly correlated with the HU value, which showed a strong correlation with the BMD of the femoral neck on DXA (r = 0.92). In 25 ONFH patients and 25 propensity-matched control participants, no significant difference was found in the HU value of the ROI (p = .54). The mean HU value of the lateral boundary in patients with subsequent collapse was found to be significantly higher than that in patients without subsequent collapse (p < .01). The assessment of HU values on CT was useful for the evaluation of BMD of the femoral head. The current assessment did not demonstrate reduced bone mineral density of the necrotic lesion in pre-collapse ONFH.

The Impact of Emotional Music on Active ROI in Patients with Depression Based on Deep Learning: A Task-State fMRI Study

With the continuous development of science, more and more research results have proved that machine learning is capable of diagnosing and studying the major depressive disorder (MDD) in the brain. We propose a deep learning network with multibranch and local residual feedback, for four different types of functional magnetic resonance imaging (fMRI) data produced by depressed patients and control people under the condition of listening to positive- and negative-emotions music. We use the large convolution kernel of the same size as the correlation matrix to match the features and obtain the results of feature matching of 264 regions of interest (ROIs). Firstly, four-dimensional fMRI data are used to generate the two-dimensional correlation matrix of one person’s brain based on ROIs and then processed by the threshold value which is selected according to the characteristics of complex network and small-world network. After that, the deep learning model in this paper is compared with support vector machine (SVM), logistic regression (LR), k-nearest neighbor (kNN), a common deep neural network (DNN), and a deep convolutional neural network (CNN) for classification. Finally, we further calculate the matched ROIs from the intermediate results of our deep learning model which can help related fields further explore the pathogeny of depression patients.

Abnormal Morphology of Select Cortical and Subcortical Regions in Neurofibromatosis Type 1.

Purpose To evaluate whether patients with neurofibromatosis type 1 (NF1)-a multisystem neurodevelopmental disorder with myriad imaging manifestations, including focal transient myelin vacuolization within the deep gray nuclei, brainstem, and cerebellum-exhibit differences in cortical and subcortical structures, particularly in subcortical regions where these abnormalities manifest. Materials and Methods In this retrospective study, by using clinically obtained three-dimensional T1-weighted MR images and established image analysis methods, 10 intracranial volume-corrected subcortical and 34 cortical regions of interest (ROIs) were quantitatively assessed in 32 patients with NF1 and 245 age- and sex-matched healthy control subjects. By using linear models, ROI cortical thicknesses and volumes were compared between patients with NF1 and control subjects, as a function of age. With hierarchic cluster analysis and partial correlations, differences in the pattern of association between cortical and subcortical ROI volumes in patients with NF1 and control subjects were also evaluated. Results Patients with NF1 exhibited larger subcortical volumes and thicker cortices of select regions, particularly the hippocampi, amygdalae, cerebellar white matter, ventral diencephalon, thalami, and occipital cortices. For the thalami and pallida and 22 cortical ROIs in patients with NF1, a significant inverse association between volume and age was found, suggesting that volumes decrease with increasing age. Moreover, compared with those in control subjects, ROIs in patients with NF1 exhibited a distinct pattern of clustering and partial correlations. Discussion Neurofibromatosis type 1 is characterized by larger subcortical volumes and thicker cortices of select structures. Most apparent within the hippocampi, amygdalae, cerebellar white matter, ventral diencephalon, thalami and occipital cortices, these neurofibromatosis type 1-associated volumetric changes may, in part, be age dependent. © RSNA, 2018 Online supplemental material is available for this article.

The combined application of magnetic resonance DTI and 3D-pcASL in differential diagnosis of hyper-acute and acute ischemic cerebral infarction

Objective: To explore the clinical value of magnetic resonance diffusion tensor imaging (DTI) combined with 3D pseudo continuous arterial spin labeling (3D-pcASL) perfusion imaging in differential diagnosis of hyper-acute and acute ischemic cerebral infarction. Methods: A total of 42 patients with confirmed unilateral ischemic cerebral infarction from February 2015 to October 2017 of Affiliated Yancheng Hospital of Southeast University Medical College were collected. DTI and 3D-pcASL images of hyper-acute (14 patients, group A) and acute (28 patients, group B) ischemic cerebral infarction were retrospectively analyzed. The slice with the biggest lesion on diffusion weighted imaging (DWI) was selected to measure the infarction area (S(DWI)) and abnormal cerebral blood flow (CBF) perfusion area (S(CBF)). Regions of interest (ROIs) were set on the infarction core (IC) area, mismatch area of S(CBF) and S(DWI) (MACD), and their corresponding contralateral regions. The values of CBF, average diffusion coefficient (DC(avg)), and fractional anisotropy (FA) parameter images in these ROIs in patients with both S(CBF)>S(DWI) and lower perfusion in the IC were recorded. The relative values of each infarction lesion to its corresponding contralateral region (rCBF, rFA, and rDC(avg)) were calculated. Differences of each parameter value between the IC, MACD and their corresponding contralateral regions and of the relative values between group A and group B were investigated. Results: The CBF and DC(avg) values in the IC and the CBF value in the MACD were lower than that of their corresponding contralateral regions in both groups (P<0.05). The DC(avg) in the MACD in group A patients and the FA in the IC in group B patients were lower than that in their corresponding contralateral regions (P<0.05). Compared to group A patients, group B patients showed decreased rFA, rDC(avg) in the IC and rFA in the MACD, and increased rDC(avg) and rCBF in the MACD (P<0.05). Receiver operating characteristics (ROC) curve analysis indicated that the best diagnosis cut off values of the rFA and rDC(avg) values in the IC and the rCBF, rFA, and rDC(avg) values in the MACD were 0.890 and 0.541 and 1.139, 0.902 and 0.455, respectively, for identifying two groups. Conclusion: The changes of the CBF, FA, and DC(avg) values and their relative values can be applied to differentially diagnose patients with hyper-acute and acute cerebral infarction, which could provide the basis for selecting more reasonable treatment protocols.

Resting frontal EEG asymmetry patterns in adolescents with and without major depression

More right-sided frontal brain resting activity has been postulated to be a correlate of major depression in adults. In children and adolescents, more right-sided activity (as indicated by more left-sided alpha activity) seems to be associated with psychosocial risk factors. However, an association of frontal asymmetry and manifest unipolar depression has not been shown in adolescents so far.We analyzed frontal asymmetry in 20 adolescents (12–17 years) with unipolar depression (12 with first episode, 8 with recurrent depression) and 31 healthy age-matched controls. We found significantly less left-sided alpha power over frontal Regions of Interest in patients, while controls exhibited no asymmetry. In the control group, more left-sided frontal alpha correlated with higher depression scores, which was not observed in the patient group.Our results suggest developmental effects on frontal asymmetry, and prompt further investigations in adolescents to clarify the role of frontal asymmetry in adolescent major depression.

Diffusion Tensor MR Imaging Evaluation of Callosal Abnormalities in Schizophrenia: A Meta-Analysis.

Widespread white matter (WM) abnormalities have been found in patients with schizophrenia. Corpus callosum (CC) is the key area that connects the left and right brain hemispheres. However, the results of studies considering different subregions of the CC as regions of interest in patients with schizophrenia have been inconsistent. To obtain a more consistent evaluation of the diffusion characteristics change of the corpus callosum (CC) related to schizophrenia. A meta-analysis involving fractional anisotropy (FA) values in the CC of 729 schizophrenic subjects and 682 healthy controls from 22 studies was conducted. Overall FA values in the CC of the schizophrenic group were less than that of the healthy control group [weighted mean difference (WMD) = -0.021,P< 0.001]. So were the FA values in the genus region (WMD = -0.019, P< 0.001) and the splenium region (WMD = -0.020, P< 0.001) of the CC respectively. The FA reduction was also significant in subjects with chronic schizophrenia (WMD = -0.032, P< 0.001) and first-episode schizophrenia (WMD = -0.014, P = 0.001). In present study, we demonstrated an overall FA decrease in the CC of schizophrenic patients. In the two subgroup analyses of the genu vs splenium region and chronic vs first-episode schizophrenia, the decrease of all groups was significant. Further studies with more homogenous populations and standardized DTI protocols are needed to confirm and extend these findings.

Traumatic axonal injury: Relationships between lesions in the early phase and diffusion tensor imaging parameters in the chronic phase of traumatic brain injury.

This prospective study of traumatic brain injury (TBI) patients investigates fractional anisotropy (FA) from chronic diffusion tensor imaging (DTI) in areas corresponding to persistent and transient traumatic axonal injury (TAI) lesions detected in clinical MRI from the early phase. Thirty-eight patients (mean 24.7 [range 13-63] years of age) with moderate-to-severe TBI and 42 age- and sex-matched healthy controls were included. Patients underwent 1.5-T clinical MRI in the early phase (median 7 days), including fluid-attenuated inversion recovery (FLAIR) and T2* gradient echo (T2*GRE) sequences. TAI lesions from the early phase were characterized as nonhemorrhagic or microhemorrhagic. In the chronic phase (median 3 years), patients and controls were imaged at 3 T with FLAIR, T2*GRE, T1, and DTI sequences. TAI lesions were classified as transient or persistent. The FLAIR/T2*GRE images from the early phase were linearly registered to the FA images from the chronic phase and lesions manually segmented on the FA-registered FLAIR/T2*GRE images. For regions of interest (ROIs) from both nonhemorrhagic and microhemorrhagic lesion, we found a significant linear trend of lower mean FA from ROIs in healthy controls to ROIs in patients without either nonhemorrhagic or microhemorrhagic lesions and further to transient and finally persistent lesion ROIs (P < 0.001). Histogram analyses showed lower FA in persistent compared with transient nonhemorrhagic lesion ROIs (P < 0.001), but this was not found in microhemorrhagic lesion ROIs (P = 0.08-0.55). The demonstrated linear trend of lower FA values from healthy controls to persistent lesion ROIs was found in both nonhemorrhagic and microhemorrhagic lesions and indicates a gradual increasing disruption of the microstructure. Lower FA values in persistent compared with transient lesions were found only in nonhemorrhagic lesions. Thus, clinical MRI techniques are able to depict important aspects of white matter pathology across the stages of TBI. © 2016 Wiley Periodicals, Inc.

Structural connectivity changes in temporal lobe epilepsy: Spatial features contribute more than topological measures.

BackgroundPrevious studies reported reduced volumes of many brain regions for temporal lobe epilepsy (TLE). It has also been suggested that there may be widespread changes in network features of TLE patients. It is not fully understood, however, how these two observations are related.MethodsUsing magnetic resonance imaging data, we perform parcellation of the brains of 22 patients with left TLE and 39 non-epileptic controls. In each parcellated region of interest (ROI) we computed the surface area and, using diffusion tensor imaging and deterministic tractography, infer the number of streamlines and their average length between each pair of connected ROIs. For comparison to previous studies, we use a connectivity ‘weight’ and investigate how ROI surface area, number of streamlines & mean streamline length contribute to such weight.ResultsWe find that although there are widespread significant changes in surface area and position of ROIs in patients compared to controls, the changes in connectivity are much more subtle. Significant changes in connectivity weight can be accounted for by decreased surface area and increased streamline count.ConclusionChanges in the surface area of ROIs can be a reliable biomarker for TLE with a large influence on connectivity. However, changes in structural connectivity via white matter streamlines are more subtle with a relatively lower influence on connection weights.

Resting-state functional connectivity in post-stroke expressive aphasia：a preliminary study

Objective To analyze the resting-state functional connectivity of the left posterior inferior frontal gyrus in normal subjects with functional MRI and to investigate its preliminary application in post-stroke aphasia.Methods Eleven male patients with post-stroke aphasia and 11 male normal subjects were recruited in this study.Resting-state fMRI data were obtained with GE 1.5 T Twin speed MR Scanner.The fMRI data were processed with SPM2, AFNI and Matlab programs.Based on the results of previous fMRI study with category member generation task , the region of interest ( ROI ) was created in the left posterior inferior frontal gyrus The time course correlations between the ROI and other voxels within whole brain were analyzed.Intra-and inter-group analysis was performed with single sample t-test and two sample t-test.Results Brain regions showed positive resting-state functional connectivity with the ROI in normal subjects including left inferior/middle frontal gyrus , left premotor cortex , left precuneus , left insula , left putamen, right inferior frontal gyrus, right cerebellum and bilateral inferior parietal lobules (voxels 33-809, t=5.80-23.55,P<0.005,uncorrected).Brain regions functionally connected with the ROI in patients with post-stroke aphasia included left inferior/middle frontal gyrus , left premotor cortex , left precuneus , left inferior parietal lobules and right inferior frontal gyrus ( voxels 34-833, t =5.08-20.34, P<0.005, uncorrected ).The left fusiform gyrus was the only region showed significantly decreased functional connectivity with the ROI in the patients group (voxels 84,t=6.25,P<0.005, uncorrected).Conclusions The neural network related to language output exists in normal subjects at the resting-state.Resting-state functional connectivity can be used to investigate the neural mechanism of development and restoration of post-stroke aphasia. Key words: Stroke ; Aphasia ; Magnetic resonance imaging ;

Diffusion Tensor Magnetic Resonance Imaging in Patients with Multiple Sclerosis and its Relationship with Disability

Multiple sclerosis is a chronic inflammatory demyelinating disease of the central nervous system. Diffusion tensor magnetic resonance imaging (DTI) can yield important information on the in vivo pathological processes affecting water diffusion. The aim of this study was to quantitatively define water diffusion in normal-appearing white matter (NAWM) distant from the plaque, in the plaque, and around the plaque, and to investigate the correlation of these changes with clinical disability. Conventional MRI and DTI scans were conducted in 30 patients with MS and 15 healthy individuals. Fractional anisotropy maps and visible diffusion coefficients were created and integrated with T2-weighted images. Regions of interest (ROIs) were placed on the plaques on the same side, white matter around the plaques and NAWM on the opposite side. Only the white matter of healthy individuals in the control group, and FA and ADC values were obtained for comparison. The highest FA and lowest ADC were detected in the control group at the periventricular region, cerebellar peduncle and at all ROIs irrespective of location. There was a significant difference in comparison to the control group at all ROIs in patients with MS (p < 0.001 for all comparisons). No significant correlation between diffusion parameters and expanded disability state scale (EDSS) scores was found in patients with MS. DTI may provide more accurate information on the damage due to the illness, compared to T2A sequences, but this damage may not be correlated with the clinical disability measured by EDSS score.

Axial Diffusivity and Tensor Shape as Early Markers to Assess Cerebral White Matter Damage Caused by Brain Tumors Using Quantitative Diffusion Tensor Tractography

We investigated the usefulness of diffusion tensor tractography (DTT) for differentiating between histological pathologies and evaluating white matter (WM) damage resulting from brain tumors. We also sought to categorize the appearance of brain tumor-related WM tract changes. A total of 18 inpatients with intracranial neoplasms were enrolled. MRI examinations were performed at 3 T using an 8-channel phased array coil. DTT was reconstruction from the raw data of diffusion tensor imaging. WM tract-based analysis of the mean diffusivity (MD), eigenvalues (λ(1) , λ(2) , λ(3) ), and fractional anisotropy (FA) was performed by the manual placement of regions of interest (ROIs) on the color-coded FA maps using DTIStudio software. The axial diffusivity (DA, namely λ(1) ) and the tensor shape (Cl, namely (λ(1) -λ(2) )/3 (λ)) were also compared between groups. P values <0.05 were considered statistically significant. In cases of low-grade glioma (LGG), the tracts adjacent to the tumors displayed the highest levels of invasion. Tract disruption was mainly observed in cases of high-grade glioma (HGG). We found significant differences regarding the FA, MD, DA, and radial diffusivity between ROIs in patients with LGG or HGG. There were also significant differences in DA and tensor shape (Cl) between patients with LGG and HGG. Axial diffusivity and Cl may be useful early markers for differentiating between LGG and HGG.

High sheer stress, calculated by strain and strain rate imaging, is associated with acute cerebral infarction

AimsThe purpose of this study was to evaluate the reliability of strain and strain rate imaging for detecting carotid plaques elastic characteristics, and the correlation between plaque fibrous cap strain...

Diffusion tensor MR imaging (DTI) metrics in the cervical spinal cord in asymptomatic HIV-positive patients

IntroductionThis study was conducted to compare diffusion tensor MR imaging (DTI) metrics of the cervical spinal cord in asymptomatic human immunodeficiency virus (HIV)-positive patients with those measured in healthy volunteers, and to assess whether DTI is a valuable diagnostic tool in the early detection of HIV-associated myelopathy (HIVM).MethodsMR imaging of the cervical spinal cord was performed in 20 asymptomatic HIV-positive patients and in 20 healthy volunteers on a 3-T MR scanner. Average fractional anisotropy (FA), mean diffusivity (MD), and major (E1) and minor (E2, E3) eigenvalues were calculated within regions of interest (ROIs) at the C2/3 level (central and bilateral anterior, lateral and posterior white matter).ResultsStatistical analysis showed significant differences with regard to mean E3 values between patients and controls (p = 0.045; mixed-model analysis of variance (ANOVA) test). Mean FA was lower, and mean MD, mean E1, and mean E2 were higher in each measured ROI in patients compared to controls, but these differences were not statistically significant.ConclusionAsymptomatic HIV-positive patients demonstrate only subtle changes in DTI metrics measured in the cervical spinal cord compared to healthy volunteers that currently do not support using DTI as a diagnostic tool for the early detection of HIVM.

Rotational micro‐CT using a clinical C‐arm angiography gantry

Rotational angiography (RA) gantries are used routinely to acquire sequences of projection images of patients from which 3D renderings of vascular structures are generated using Feldkamp cone-beam reconstruction algorithms. However, these systems have limited resolution (<4 lp/mm). Micro-computed tomography (micro-CT) systems have better resolution (>10 lp/mm) but to date have relied either on rotating object imaging or small bore geometry for small animal imaging, and thus are not used for clinical imaging. The authors report here the development and use of a 3D rotational micro-angiography (RMA) system created by mounting a micro-angiographic fluoroscope (MAF) [35 microm pixel, resolution >10 microp/mm, field of view (FOV)=3.6 cm] on a standard clinical FPD-based RA gantry (Infinix, Model RTP12303J-G9E, Toshiba Medical Systems Corp., Tustin, CA). RA image sequences are obtained using the MAF and reconstructed. To eliminate artifacts due to image truncation, lower-dose (compared to MAF acquisition) full-FOV (FFOV) FPD RA sequences (194 microm pixel, FOV=20 cm) were also obtained to complete the missing data. The RA gantry was calibrated using a helical bead phantom. To ensure high-quality high-resolution reconstruction, the high-resolution images from the MAF were aligned spatially with the lower-dose FPD images, and the pixel values in the FPD image data were scaled to match those of the MAF. Images of a rabbit with a coronary stent placed in an artery in the Circle of Willis were obtained and reconstructed. The MAF images appear well aligned with the FPD images (average correlation coefficient before and after alignment: 0.65 and 0.97, respectively) Greater details without any visible truncation artifacts are seen in 3D RMA (MAF-FPD) images than in those of the FPD alone. The FWHM of line profiles of stent struts (100 microm diameter) are approximately 192+/-21 and 313+/-38 microm for the 3D RMA and FPD data, respectively. In addition, for the dual-acquisition 3D RMA, FFOV FPD data need not be of the highest quality, and thus may be acquired at lower dose compared to a standard FPD acquisition. These results indicate that this system could provide the basis for high resolution images of regions of interest in patients with a reduction in the integral dose compared to the standard FPD approach.