PURPOSE: To explore the potential relation between whole-tumor apparent diffusion coefficient (ADC) parameters in viable parts of tumor and histopathological findings in nephroblastoma. MATERIALS AND METHODS: Children (n = 52) with histopathologically proven nephroblastoma underwent diffusion-weighted magnetic resonance imaging (MRI) (1.5T) before preoperative chemotherapy. Of these, 25 underwent an additional MRI after ... read more preoperative chemotherapy, shortly before resection. An experienced reader performed the whole-tumor ADC measurements of all lesions, excluding nonenhancing areas. An experienced pathologist reviewed the postoperative specimens according to standard SIOP guidelines. Potential associations between ADC parameters and proportions of histological subtypes were assessed with Pearsons or Spearmans rank correlation coefficient depending on whether the parameters tested were normally distributed. In case the Mann-Whitney U-test revealed significantly different ADC values ...
Background: Magnetic resonance imaging (MRI) has become a diagnostic and problem solving method for the breast examinations in addition to conventional breast examination methods. Diffusion-weighted imaging (DWI) adds valuable information to conventional MRI.. Aims: Our aim was to show the impact of apparent diffusion coefficient (ADC) values acquired with DWI to differentiate benign and malignant breast lesions.. Study Design: Diagnostic accuracy study.. Methods: Forty-six women with 58 breast masses (35 malignant, 23 benign) were examined on a 1.5 T clinical MRI scanner. The morphologic characteristics of the lesions on conventional MRI sequences and contrast uptake pattern were assessed. ADC values of both lesions and normal breast parenchyma were measured. The ADC values obtained were statistically compared with the histopathologic results using Paired Samples t-Test.. Results: Multiple lesions were detected in 12 (26%) of the patients, while only one lesion was detected in 34 (74%). ...
Six men performed ankle plantar flexion exercises with eccentric contraction. The fractional anisotropy (FA), λ1, λ2, λ3, mean diffusivity (MD), and T2 values in the triceps surae muscles were measured by magnetic resonance diffusion tensor and spin-echo imaging. Passive torque of plantar flexors, maximal voluntary isometric plantar flexion torques (MVIP), and Achilles tendon stiffness during MVIP were measured by combined ultrasonography and dynamometry. Plasma creatine kinase and muscle soreness were also assessed. These parameters were measured before and 1-8 days postexercise. ...
MR examinations (Achieva 3 T, Philips, Best, The Netherlands) were performed at five different occasions in a healthy volunteer (male 60 years) and in one renal cancer patient (male 78 years) with normal renal function (creatinine 88 μmol/L). Intravoxel incoherent motion (IVIM) coefficients D + D* were measured using respiratory-triggered diffusion-weighted spin-echo echo-planar imaging. Perfusion data of the patient were acquired using a saturation-recovery gradient-echo sequence and with the bolus of Gd-BOPTA (Multihance). D + D* were computed by monoexponential fitting of MR signal intensity attenuation versus b for b = 0, 50, 100, 150 s/mm2. Perfusion parameters were evaluated with "NordicICE" software. The map of D + D* was compared qualitatively with the perfusion map computed from the Gd scan. D + D* values of the cortex and medulla were in the range 2.3-2.7 and 1.1-1.6 × 10-3 mm2/s, respectively. In conclusion, in this pilot study a good qualitative relation between IVIM variables D + ...
DOWNLOADSPseudo-diffusion and diffusion magnetic resonance tensor imaging Pseudo-diffusion and diffusion magnetic resonance tensor imaging &nbs...
Objective This study aimed to investigate the reliability of intravoxel incoherent motion (IVIM) model derived parameters D and f and their dependence on b value distributions with a rapid three b...
Liver intravoxel incoherent motion (IVIM) magnetic resonance imaging: a comprehensive review of published data on normal values and applications for fibrosis and tumor evaluation
The analysis of DTI images showed that injured nerves have lower FA values as compared to the naïve nerves. It suggests that in area distally to coaptation site of injured nerves water diffuses in various directions indicating low structural integrity whereas most of the water inside of the naïve nerve diffuses in the same direction. FA has increased or did not change in the proximal and transection segment of injured nerve across groups from 2 to 5 weeks post-surgery. In the distal segment, FA value has increased by a noticeable margin in IGF-1 group and to a lesser degree, in FK506 treated group. This correlated strongly with changes in GAP43 expression, neurofilament M and myelin expressions in the distal nerve fragment ...
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The aim of this study was to develop a fast method for estimating whether a brain volume loss is within the normal range for the respective age of the patient.A readout-segmented diffusion weighted EPI sequence was performed as part of the routine examination at a 3T scanner. Data without (B0-image) and with diffusion weighting (1000 s/mm2) from 492 patients were examined. 173 data sets had to be excluded due to brain lesions or to pathological enlarged CSF spaces. In the remaining 319 data sets, ADC values were calculated for all pixels exceeding a combined threshold in the diffusion weighted data and in the non-diffusion weighted data. The first part of the histogram represents pixels containing mostly brain tissue. The percentage of number of pixels in this part of the ADC histograms was evaluated for all patients and was correlated with the age of the patients.In all the areas examined, a monotone change of relative pixel numbers with the age of the patients was found. The reduction of the
Whole body diffusion-weighted imaging is a functional magnetic resonance imaging technique that characterizes tissue by probing changes in water diffusion secondary to differences in the tissue microstructure. These changes in water diffusion result in differences in signal intensity on diffusion-weighted images that are quantified with the apparent diffusion coefficient (ADC). In malignant lesions, the extravascular extracellular space (EES) will be diminished, due to the increased number of cells. This will restrict water diffusion, identified by increased signal intensity (SI) on native diffusion-weighted images and low ADC. Contrary, in tissue with low cellularity, like benign lesions and treatment induced necrosis, the EES will be enlarged due to the lower density of cells, or in case of necrosis, the complete absence of cellular organization. This will facilitate water diffusion, leading to absent SI on native diffusion-weighted images and high ADC.. The purpose of this study is to image ...
Background & Purpose: Diffusion weighted image (DWI) is indispensable in the early diagnosis of acute ischemic stroke. However, DWI cannot always detect an acute ischemic lesion. We investigated the clinical features and outcome of stroke patients without an ischemic lesion on the initial DWI.. Subjects & Methods: Among the consecutive 3062 patients with sudden neurological deficits who were admitted to the 7 stroke centers in Fukuoka prefecture Japan within 24 hours after the symptom onset, 1731 patients with neurological deficits duration of 24 hours or more and pre-stroke modified Rankin scale (mRS) of 0 or 1 were included in the present study. All patients underwent MRI studies including DWI. We investigated clinical features, a neurological deterioration (a NIHSS score worsening of ≥1-point), and stroke recurrence.. Results: Among 1731 patients, 102 (5.9%) had no ischemic lesions on DWI (DWI-negative Group), and other 1629 had ischemic lesions on DWI (DWI-positive Group). Atrial ...
The aim of this study was to determine the usefulness of combined positron emission tomography (PET)/magnetic resonance imaging (MRI) parameters provided by simultaneous 18F-fluorodeoxyglucose (FDG) PET/MRI for the prediction of treatment failure in surgically resected head and neck cancer. We hypothesized that PET parameters corrected by tumor cellularity (combined PET/MRI parameters) could predict the prognosis. On regional PET, maximum standardized uptake value (SUVmax) was measured as metabolic parameters. In addition, metabolic tumor volume (MTV) and total lesion glycolysis (TLG) were checked as metabolo-volumetric parameters. Mean apparent diffusion coefficient (ADCmean) of tumor was evaluated as the MRI parameter on the ADC map. Ratios between metabolic/metabolo-volumetric parameters and ADC were calculated as combined PET/MRI parameters. PET, MRI, and combined PET/MRI parameters were compared with clinicopathologic parameters in terms of treatment failure. Seventy-two patients (mean age = 55.9
BACKGROUND AND PURPOSE: Dynamic CT perfusion imaging is a rapid and widely available method for assessing cerebral hemodynamics in the setting of ischemia. Nevertheless, little is known about perfusion parameters within regions of diffusion abnormality. Since MR diffusion-weighted (DW) imaging is widely considered the most sensitive and specific technique to examine the ischemic core, new knowledge about CT perfusion findings in areas of abnormal diffusion would likely provide valuable information. The purpose of our study was to measure the CT-derived perfusion values within acute ischemic lesions characterized by 1) increased signal intensity on DW images and 2) decreased apparent diffusion coefficient (ADC) and compare these values with those measured in contralateral, normal brain tissue.. METHODS: Analysis was performed in 10 patients with acute middle cerebral artery territory stroke of symptom onset less than 8 hours before imaging who had undergone both CT perfusion and DW imaging within ...
An ovine model can cast great insight in translational neuroscientific research due to its large brain volume and distinct regional neuroanatomical structures. The present study examined the applicability of brain functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) to sheep using a clinical MR scanner (3 tesla) with a head coil. The blood-oxygenation-level-dependent (BOLD) fMRI was performed on anesthetized sheep during the block-based presentation of external tactile and visual stimuli using gradient echo-planar-imaging (EPI) sequence. The individual as well as group-based data processing subsequently showed activation in the eloquent sensorimotor and visual areas. DTI was acquired using 26 differential magnetic gradient directions to derive directional fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values from the brain. White matter tractography was also applied to reveal the macrostructure of the corticospinal tracts and optic radiations. Utilization
PURPOSE: The purpose of this study was to measure potential changes of the apparent diffusion coefficient (ADC) in diffusion-weighted imaging of the liver before and after caloric challenge in correlation to the induced changes in portal vein flow. MATERIALS AND METHODS: The study was approved by the local ethics committee. Each of 10 healthy volunteers underwent 4 measurements in a 1.5-T whole-body magnetic resonance scanner on 2 different days: a first scan after fasting for at least 8 hours and a second scan 30 minutes after intake of a standardized caloric either a protein- or carbohydrate-rich meal. Diffusion-weighted spin-echo echo-planar magnetic resonance images were acquired at b values of 0, 50, 150, 250, 500, 750, and 1000 s/mm. In addition, portal vein flow was quantified with 2-dimensional phase-contrast imaging (velocity encoding parallel to flow direction, 60 cm/s). Mean ADC values for regions of interest in 3 different slices were measured from b50 to b250 and from b500 to b1000 ...
To compare diffusion tensor imaging (DTI), intravoxel incoherent motion (IVIM), and tri-exponential models of the diffusion magnetic resonance imaging (MRI) signal for the characterization of renal lesions in relationship to histopathological findings. Sixteen patients planned to undergo nephrectomy for kidney tumour were scanned before surgery at 3 T magnetic resonance imaging (MRI), with T2-weighted imaging, DTI and diffusion weighted imaging (DWI) using ten b-values. DTI parameters (mean diffusivity [MD] and fractional anisotropy [FA]) were obtained by iterative weighted linear least squared fitting of the DTI data and bi-, and tri-exponential fit parameters (Dbi, fstar,and Dtri, ffast,finterm) using a nonlinear fit of the multiple b-value DWI data. Average parameters were calculated for regions of interest, selecting the lesions and healthy kidney tissue. Tumour type and specificities were determined after surgery by histological examination. Mean parameter values of healthy tissue and solid lesions
BACKGROUND AND PURPOSE: Many patients with transient ischemic attack (TIA) or minor stroke present to medical attention after a delay of several days or weeks, at which time it may be more difficult to obtain a clear history and clinical signs may have resolved. Because ischemic lesions on diffusion-weighted MRI (DWI) often persist for several weeks, we hypothesized that adding DWI to a standard protocol with T2-weighted imaging might be useful in the management of patients presenting late. METHODS: We studied consecutive patients with TIA or minor stroke presenting | or =3 days after the event. Two independent observers recorded the presence or absence of recent ischemic lesions on 2 different occasions, first with the T2 scan only, and second with T2 and DWI. Each time, with the aid of a written clinical summary, the observers recorded their diagnosis and proposed management. RESULTS: 300 patients (159 men) were scanned at a median of 17 (interquartile range=10 to 23) days after symptom onset. DWI
The thalamus is an essential relay station in the cortical-subcortical connections. It is characterized by a complex anatomical architecture composed of numerous small nuclei, which mediate the involvement of the thalamus in a wide range of neurological functions. We present a novel framework for segmenting the thalamic nuclei, which explores the orientation distribution functions (ODFs) from diffusion magnetic resonance images at 3 T. The differentiation of the complex intra-thalamic microstructure is improved by using the spherical harmonic (SH) representation of the ODFs, which provides full angular characterization of the diffusion process in each voxel. The clustering was performed using the k-means algorithm initialized in a data-driven manner. The method was tested on 35 healthy volunteers and our results show a robust, reproducible and accurate segmentation of the thalamus in seven nuclei groups. Six of them closely matched the anatomy and were labeled as anterior, ventral anterior, ...
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Results The mean age of the 268 eligible patients was 64.4 years. New lesions on diffusion-weighted imaging (DWI) were detected in 117 patients (43.7%). TMAO level was higher in patients with new (DWI) lesions than in patients without new lesions (median 5.2 vs 3.2 µmol/L; p , 0.001). Increased plasma TMAO levels were associated with an increased risk of having new lesions on DWI after CAS (adjusted odds ratio for the highest vs lowest quartile, 3.85; 95% confidence interval, 1.37-7.56, p , 0.001; adjusted odds ratio for the third vs lowest quartile, 1.86; 95% confidence interval, 1.09-4.66, p = 0.02). The area under the receiver operating characteristic curve of TMAO was 0.706 for new lesions on DWI, and the optimal cutoff value was 4.29 µmol/L. The sensitivity, specificity, positive predictive value, and negative predictive value of TMAO levels ≥4.29 µmol/L for predicting new lesions on DWI were 61.5%, 74.8%, 65.5%, and 65.5%, respectively. ...
Creative DW Image Effects is a Dreamweaver extension that gives the user the ability to apply Photoshoplike effects to objects such as creating soft edges applying glow effects or creating 3D art from the simplest shapes It closes the gap
Several regularization terms are used to constrain the Magnetoencephalography (MEG) and the Electroencephalography (EEG) inverse problem. It has been shown that the brain can be divided into several regions[1] with functional homogeneity inside each one of them. To locate these regions, we use the structural information coming from the diffusion Magnetic Resonance (dMRI) and more specifically, the anatomical connectivity of the distributed sources computed from dMRI. To invistigate the importance of the dMRI in the source reconstruction, we compare the solution based on dMRI-based parcellation to random parcellation.
TY - GEN. T1 - A supervised method for calculation of perfusion/diffusion mismatch volume in acute stroke. AU - James, Judy Rose. AU - Osuntokun, Olaniyi. AU - Yoder, Karmen. AU - Bruno, Askiel. AU - Morris, Evan D.. PY - 2004/12/1. Y1 - 2004/12/1. N2 - We present our initial experience with a supervised technique for calculating the mismatch between lesion volumes on Perfusion and Diffusion weighted images of acute stroke. Our method was designed to be reliable and easy to use. It requires the intervention of a trained user at two points during the segmentation process: first to identify normal and lesion tissue, and second, to match a filter to artifact size. The time to analyze a single patient is 15 minutes or less. Statistical test showed us effect of rater or day. This performance suggests that personnel at multiple sites could use this method in future studies to evaluate the meaning and utility of the mismatch volume. Most of the variability in our measurements appears to be due to ...
Hoehn-Berlage M, Norris DG, Kohno K, Mies G, Leibfritz D, Hossmann K-A. Evolution of regional changes in apparent diffusion coefficient during focal ischemia of rat brain: the relationship of quantitative diffusion NMR imaging to reduction in cerebral blood flow and metabolic disturbance. J Cereb Blood Flow Metab 1995; 5:1002-1011 ...
BACKGROUND AND PURPOSE Concern regarding the safety of stent implantation in the carotid artery exists because of the risk of cerebral embolization during the procedure. The purpose of this prospective study was to determine the incidence of new areas of cerebral ischemia, as detected by using diffusion-weighted MR imaging after stent implantation in the carotid artery. METHODS Diffusion-weighted MR imaging of the brain was performed in 67 patients with 70 high-grade stenoses of the carotid artery before and 24 hours after stent implantation. RESULTS The neurologic status of the patients was unchanged after 69 of 70 procedures. During one procedure, symptomatic cerebral embolization occurred. Diffusion-weighted MR images showed new ipsilateral lesions after stent implantation in 20 patients (29%), including the symptomatic patient, and new contralateral lesions in six patients (9%). Fifty-two of 59 postprocedural lesions occurred in the vascular territory supplied by the treated vessel. The
TY - JOUR. T1 - Applications of diffusion/perfusion magnetic resonance imaging in experimental and clinical aspects of stroke. AU - Duong, Timothy Q.. AU - Fisher, Marc. PY - 2004/7. Y1 - 2004/7. N2 - The acute evaluation of stroke patients has undergone dramatic advances in the recent past. The increasing availability of novel magnetic resonance imaging (MRI) techniques, such as diffusion and perfusion MRI, provides a plethora of information to clinicians evaluating patients suspected of having an acute stroke. This review focuses on recent advances with experimental and clinical applications of perfusion and diffusion imaging and their utility in identifying potentially salvageable ischemic tissue in rat stroke model and stroke patients.. AB - The acute evaluation of stroke patients has undergone dramatic advances in the recent past. The increasing availability of novel magnetic resonance imaging (MRI) techniques, such as diffusion and perfusion MRI, provides a plethora of information to ...
Several investigators, using DWI to detect clinically silent embolic lesions after protected CAS, have reported new DWI lesions over a wide range, from 17.3% to 73%.1,3,4,6,10,13⇓-15,23⇓⇓⇓⇓-28 The rate of new DWI lesions in our study was lower compared with these other studies. Of 47 patients, 14.89% had new lesions after CAS with distal filter protection, and new ischemic lesions were detected in the treated vascular territory in 8.51% of patients.. A lower incidence of new DWI lesions after protected CAS (8.33%) was published in only 1 other study with fewer patients.29 Several systemic reviews have reported contradictory data concerning the rate of stroke and ischemia using protected versus unprotected CAS. The rate of new DWI lesions in our study was lower compared with unprotected CAS. Previous reports revealed rates of new lesions after unprotected CAS ranging from 18% to 68%.3,5,13,14,30⇓⇓⇓-34 Our findings are in agreement with other observational studies reporting lower ...
Computational methods are crucial for the analysis of diffusion magnetic resonance imaging (MRI) of the brain. Computational diffusion MRI can provide rich information at many size scales, including local microstructure measures such as diffusion anisotropies or apparent axon diameters, whole‐brain connectivity information that describes the brains wiring diagram and population‐based studies in health and disease. Many of the diffusion MRI analyses performed today were not possible five, ten or twenty years ago, due to the requirements for large amounts of computer memory or processor time. In addition, mathematical frameworks had to be developed or adapted from other fields to create new ways to analyze diffusion MRI data. The purpose of this review is to highlight recent computational and statistical advances in diffusion MRI and to put these advances into context by comparison with the more traditional computational methods that are in popular clinical and scientific use. We aim to provide a
High resolution diffusion tensor images of the mouse brain were acquired using the pulsed gradient spin echo sequence and the oscillating gradient spin echo sequence. The oscillating gradient spin echo tensor images demonstrated frequency-dependent changes in diffusion measurements, including apparent diffusion coefficient and fractional anisotropy, in major brain structures. Maps of the rate of change in apparent diffusion coefficient with oscillating gradient frequency revealed novel tissue contrast in the mouse hippocampus, cerebellum, and cerebral cortex. The observed frequency-dependent contrasts resembled neuronal soma-specific Nissl staining and nuclei-specific 4,6-diamidino-2-phenylindole (DAPI) staining in the mouse brain, which suggests that the contrasts might be related to key features of cytoarchitecture in the brain. In the mouse cuprizone model, oscillating gradient spin echo-based diffusion MRI revealed significantly higher frequency-dependence of perpendicular diffusivity (λ() ...
Earlier studies suggested that dysfunction of the amygdala and/or orbitofrontal cortex (OFC) may underpin psychopathy. Nobody, however, has ever studied the white matter connections (such as the uncinate fasciculus (UF)) linking these structures in psychopaths. Therefore, we used in vivo diffusion tensor magnetic resonance imaging (DT-MRI) tractography to analyse the microstructural integrity of the UF in psychopaths (defined by a Psychopathy Checklist Revised (PCL-R) score of 25) with convictions that included attempted murder, manslaughter, multiple rape with strangulation and false imprisonment. We report significantly reduced fractional anisotropy (FA) ( ...
Intramyocellular lipid (IMCL) droplets are dynamic organelles whose morphology reflects their vital roles in lipid synthesis, utilization and storage in muscle energy metabolism. To develop non-invasive means to measure droplet microstructure in vivo, we investigated the molecular diffusion behavior of IMCL with diffusion MR spectroscopy. Our results demonstrate the feasibility of MR diffusion characterization of IMCL droplet microstructure and provide evidence of the sensitivity of this method to metabolic alterations. The use of diffusion MR methodology in vivo promises to provide new biophysical insights in the investigation of droplet dynamics and lipid metabolism in both animal models and human subjects. The diffusion MR results may help contribute to an improved understanding and diagnosis of obesity, diabetes and other metabolic disorders ...
Recent research suggests that diffusion-weighted (DW) MRI, and in particular the apparent diffusion coefficient (ADC), can be used to improve the sensitivity and specificity of dynamic contrast-enhanced (DCE) MRI for the detection of breast cancer. However, to date the methods proposed for determining a representative ADC value for a suspicious lesion are highly varied. One approach is to compute the mean ADC value over the entire lesion to obtain a representative ADC value. Another is to compute the mean ADC value within one or more regions of interest (ROIs) defined on the suspicious lesion. The earliest examples of this approach involve manually defining ROIs of hypointensity to be as large as possible, but constrained within the lesion, and such that areas of necrosis are avoided in large lesions. More recent examples of this approach involve placing one or more smaller ROIs of hypointensity within a suspicious lesion and computing, for example, the global minimum [1] or mean [2]. This latter
Diffusion-weighted magnetic resonance imaging in a case of methanol intoxication.: Although decreased ADC values on diffusion-weighted imaging are commonly asso
As this case exemplifies, the inclusion of diffusion-weighted (DW) sequences in standard and fast/urgent abdominal MRI acquisition protocols may further increase the diagnostic confidence for AC rapidly and noninvasively. The inflamed gallbladder wall is visually hyperintense on high b-value DW images with apparent diffusion coefficient (ADC) values significantly lower than those observed in normal conditions and reported to fall in the range 1.68-1.96x10-3 mm2/s. The key differential diagnosis of restricted gallbladder wall diffusion are chronic cholecystitis, which lacks diffusion restriction, and cancer, which generally shows ADC values below 1.2x10 x10-3 mm2/s. Albeit some authors believe that confident differentiation is possible between malignant versus benign mural thickening, some overlap may exist between ADC values: therefore DW findings should be always interpreted in conjunction with standard MRI sequences, in which AC mural thickening is generally smooth and diffuse with preserved ...
article{7013d42c-c06e-457e-b773-bdc1b35ccc3b, abstract = {Purpose: To compare apparent diffusion coefficient (ADC) measurements from hyperpolarized (HP) helium (He-3)-magnetic resonance imaging (MRI) with quantitative data from multislice Computed Tomography (CT) (MSCT) of the whole lungs and pulmonary function tests (PFT). Materials and methods: Twenty-seven subjects, 22 with established emphysema and 5 with preclinical emphysema defined by PFT criteria, were examined with Hp He-3-MRI and MSCT. Mean age was 55 (+/- 12) years, 18 female and 9 male. Mean ADC from He-3-MRI was compared with emphysema index (EI), 15th percentile and mean lung density (MLD) values from MSCT. Both mean ADC and MSCT data were compared to PFT, especially percent of predicted diffusing capacity of carbon monoxide (%predicted DLCO), using Pearsons correlation test. Results: Mean ADC and standard deviation values were 0.392 +/- 0.119 cm(2)/s for the established emphysema group and 0.216 +/- 0.046 for the pre-clinical ...
Diffusional Kurtosis Magnetic Resonance Imaging (DKI) quantifies the extent of non-Gaussian water diffusion, which has been shown to be a sensitive biomarker for microstructure in health and disease. However, DKI is not specific to any microstructural property per se since kurtosis may emerge from several different sources. Q-space trajectory encoding schemes have been proposed for decoupling kurtosis arising from the variance of mean diffusivities (isotropic kurtosis) from kurtosis driven by microscopic anisotropy (anisotropic kurtosis). Still, these methods assume that the system is comprised of multiple Gaussian diffusion components with vanishing intra-compartmental kurtosis (associated with restricted diffusion). Here, we develop a more general framework for resolving the underlying kurtosis sources without relying on the multiple Gaussian diffusion approximation. We introduce Correlation Tensor MRI (CTI) - an approach harnessing the versatility of double diffusion encoding (DDE) and its ...
Bakke, Kine Mari; Grøvik, Endre; Meltzer, Sebastian; Negård, Anne; Holmedal, Stein Harald; Mikalsen, Lars Tore G; Lyckander, Lars Gustav; Ree, Anne Hansen; Gjesdal, Kjell-Inge; Redalen, Kathrine & Bjørnerud, Atle (2019). Comparison of Intravoxel incoherent motion imaging and multiecho dynamic contrast-based MRI in rectal cancer. Journal of Magnetic Resonance Imaging. ISSN 1053-1807. . doi: 10.1002/jmri.26740 Vis sammendrag Background Dynamic contrast‐based MRI and intravoxel incoherent motion imaging (IVIM) MRI are both methods showing promise as diagnostic and prognostic tools in rectal cancer. Both methods aim at measuring perfusion‐related parameters, but the relationship between them is unclear. Purpose To investigate the relationship between perfusion‐ and permeability‐related parameters obtained by IVIM‐MRI, T1‐weighted dynamic contrast‐enhanced (DCE)‐MRI and T2*‐weighted dynamic susceptibility contrast (DSC)‐MRI. Study Type Prospective. Subjects In all, 94 patients ...
PubMed comprises more than 30 million citations for biomedical literature from MEDLINE, life science journals, and online books. Citations may include links to full-text content from PubMed Central and publisher web sites.
We thank Drs. Paraskevas and Giannoukas for their appraisal of our work (1).. The purpose of our study was to analyze the impact of post-procedural asymptomatic cerebral ischemic lesions on diffusion-weighted magnetic resonance imaging (DW-MRI) after carotid artery stenting (CAS) on the hard endpoints of death, stroke, and myocardial infarction, which, to the best of our knowledge, has not been done before.. We completely agree that 1 limitation of our study is that neuropsychological testing was not performed. This, however, is very important because it is a matter of debate whether these lesions negatively affect cognitive function. We are thankful to Drs. Paraskevas and Giannoukas for drawing our attention to a small but very interesting study (2) that was published after our paper was submitted. This paper and other only recently published work (3) are important findings admonishing us to take those "asymptomatic lesions" seriously.. Obviously, we are just beginning to understand the meaning ...
Diffusion-Weighted Magnetic Resonance Imaging (DWI) obtains information useful in diagnosing several diseases through the measurement of random, Brownian diffusion of water molecules in tissues. This pictorial essay illustrates the main factors, i.e., ratio between the volume occupied by cells and the extracellular space, composition of the extracellular space, and temperature, that determine the rate of the water diffusion. The mechanism through which these influencing factors affect water diffusion is explained. Clinical and experimental examples, derived both from physiology and from non-human models, are described.
BACKGROUND: Early risk of stroke after a transient ischaemic attack (TIA) can be reliably predicted with risk scores based on clinical features of the patient and the event, but it is unclear how these features correlate with findings on brain imaging and few studies have investigated this in the subacute phase. METHODS: Two hundred consecutive patients attending a specialist clinic underwent diffusion-weighted brain imaging (DWI) on the day of the clinic (| or =3 days after a TIA) and the presence of recent lesions (positive DWI) was related to the presence of clinical features associated with a high stroke risk and to 2 validated risk scores (ABCD and California). RESULTS: Thirty-one patients (16%) had positive DWI. Increasing ABCD and California scores were associated with positive DWI (p = 0.02 for both) independent of the delay from TIA to scan. CONCLUSION: Presence of recent ischaemic lesions on DWI correlates with validated clinical scores for risk of stroke after TIA in patients scanned
The diffusion-sensitive gradient field parameter applied in DWI is expressed as b-value [2]. The apparent diffusion coefficient (ADC) value reflects changes in tissue cells, and is negatively correlated with changes in cells within the tissue. DWI differs between organizations mainly by a different b-value. Theoretically, the higher b-value, the closer the signal appears to the real tissue ADC value. Although 3.0 T MRI has good imaging properties for our purposes, visceral artifacts of the upper abdomen appear on the DWI sequence, which affects the measurement of ADC value [3]. This drawback leads to errors in the region of interest (ROI); within the blood vessels, pancreatic duct, and the spatial resolution, signal to noise ratio and other effects, the final ADC value therefore does not accurately reflect the tumors pathological conditions. DADC (difference of ADC) was therefore selected to observe the different tissues. Most publications concerning b-values in the past focused on human study. ...
The study aimed to evaluate the utility of diffusion-weighted imaging (DWI) and to assess the response of breast cancer patients to neoadjuvant chemotherapy (NAC), based on morphological concepts. This retrospective study included 35 breast cancer patients (36 lesions) who had conventional magnetic resonance imaging (MRI), with DWI acquired before and after NAC. The morphological pattern of delayed enhancement on MRI before NAC was classified into two types: focal mass (FM), and multiple masses and/or non-mass like (MM/NM), based on Breast Imaging Reporting and Data System (BI-RADS). Of the 36 tumors, 26 were classified as FM and 10 as MM/NM. Tumors were clearly visualized on the initial DWI although one case of suspected MM/NM was not observed on DWI following NAC. A correlation was found between changes in the apparent diffusion coefficient and response rates to NAC in FM tumors (r=0.608, ...
Diffusion-weighted nuclear magnetic resonance imaging has been shown to detect early ischemia-related alterations in experimental stroke. This raises the question of whether the observed increase in signal intensity is correlated with changes in cerebral metabolism. After middle cerebral artery occlusion, nuclear magnetic resonance diffusion images were recorded and compared with the regional concentration of cerebral metabolites and with histology of identical planes.. Seven anesthetized Fischer rats were subjected to permanent occlusion of the middle cerebral artery. T1, T2, and diffusion images (b factors ranging from 0 to 1500 s/mm2) were measured in three to five planes after 7 hours. Thereafter, brains were frozen in situ for histology and quantitative bioluminescence imaging of ATP, glucose, lactate, and for fluorescence imaging of tissue pH.. Seven hours after middle cerebral artery occlusion, the apparent diffusion coefficient was reduced from 615 +/- 97 x 10(-6).mm2.s-1 (contralateral ...
The incidence of hepatocellular carcinoma (HCC) has recently increased in the US mostly due to an increase in chronic hepatitis C infection. Angiogenesis is critical for the growth and metastatic progression of HCC. With the development of new antiangiogenic drugs such as sorafenib, imaging methods to predict and assess therapeutic response beyond changes in size become critical. However, validated imaging methods to predict and assess early HCC response to targeted agents are lacking.. In this study, the investigators would like to develop quantitative MRI methods interrogating different features of HCC tumor biology and pathology, including tumor cellularity, grade, angiogenesis and hypoxia. The investigators propose a multiparametric approach combining advanced DWI (IVIM: intravoxel incoherent motion diffusion measuring perfusion fraction and true diffusion coefficient), DCE-MRI (dynamic contrast-enhanced MRI, which measures arterial and portal flow, mean transit time, blood volume and ...
BJ Casey, Matt Davidson, Katie Thomas. Outline. Background. Diffusion ... D.J. Werring, C.A. Clark, G.J.M. Parker, D.H. Miller, A.J. Thompson, G.J. Barker ... – A free PowerPoint PPT presentation (displayed as a Flash slide show) on PowerShow.com - id: 516f7-ZDc1Z
OBJECTIVE: To explore the clinical application of diffusion-weighted magnetic resonance imaging (DWI) in nasopharyngeal carcinoma (NPC) diagnosis, detection of lymph node metastasis, radiotherapy and prognosis. METHODS: Twenty patients with diagnosed
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This is the largest longitudinal study to date to investigate the temporal evolution of water diffusion parameters in grey and white matter after stroke using DT-MRI. The above results show that there are differences in the temporal evolution of ,D, and FA of grey and white matter in ischaemic lesions affecting both tissue types. Although the overall evolution of ,D,{grey} and ,D,{white} was similar, subtle differences were observed during the first two weeks after stroke, specifically the rate of increase of ,D,{grey} was faster between 4-7 and 10-14 days. Differences in the evolution of grey and white matter FA were more marked, with the loss of FA{white} being significantly greater than FA{grey} during the first week after stroke.. Previous studies reporting changes in grey and white matter water diffusivity indices have shown contradictory results. As in the current study, Yang et al and Mukherjee et al have found that ,D,R was significantly more reduced in white than grey matter at less ...