Histogram-based characterization of healthy and ischemic brain tissues using multiparametric MR imaging including apparent diffusion coefficient maps and relaxometry

Bernarding, Johannes; Braun, J.; Hohmann, Joachim; Mansmann, Ulrich; Hoehn‐Berlage, Mathias; Stapf, Christian; Wolf, K.-J.; Tolxdorff, Thomas

doi:10.1002/(sici)1522-2594(200001)43:1<52::aid-mrm7>3.0.co;2-5

Cited by 45 publications

(32 citation statements)

References 29 publications

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“…25 Thus, it has to be corrected for these physiologically occurring low ADC values. Otherwise, these voxels within the affected hemisphere would be misinterpreted to represent ischemic tissue.…”

Section: Postprocessingmentioning

confidence: 75%

Severe ADC Decreases Do Not Predict Irreversible Tissue Damage In Humans

Fiehler

Foth

Kucinski

et al. 2002

Stroke

244

153

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Background and Purpose-A mismatch between diffusion-and perfusion-weighted MRI is thought to define tissue at risk of infarction. This concept is based on the assumption that diffusion slowing of and decreases in the apparent diffusion coefficient (ADC) serve as indicator of tissue proceeding to infarction. We tested this hypothesis. Methods-MRI (diffusion weighted, perfusion weighted, MRA, T2 weighted) was performed in 15 patients with acute stroke within 2.9Ϯ0.8 hours (meanϮSD) of onset and on days 1 and 7. After intraindividual realignment of the ADC maps, the development of ADC range volumes and ADC values was determined. Results-An increase (354%, group A1) in the total ADC-based lesion volume below a threshold of Ͻ80% occurred in 4 patients on day 1, persisting on day 7 with a pronounced increase of ADC range volumes with low ADC values. An increase in total ADC-based lesion volume (201%, group A2) followed by a secondary drop to day 7 was found in 7 patients. A significant reduction in total ADC-based lesion volume (14%, group B) was found in 4 patients. ADC-based lesion volume increase was associated with persistent vessel occlusion in group A, whereas recanalization in group B resulted in ADC volume decrease. ADC normalization was observed independently from the degree of the initial ADC decrease on days 1 and 7 in group B. Conclusions-In

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Section: Postprocessingmentioning

confidence: 75%

Severe ADC Decreases Do Not Predict Irreversible Tissue Damage In Humans

Fiehler

Foth

Kucinski

et al. 2002

Stroke

244

153

View full text Add to dashboard Cite

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“…55 Given the potential pitfalls associated with using the ADC alone as a predictor of ischemic injury, a number of investigators have attempted to combine the ADC information with that of other MR parameters to unambiguously stage and predict ischemic brain injury over its entire temporal evolution. 18,22,28,[56][57][58][59][60][61][62][63][64][65] Although DTI has not been employed as a parameter in many of these investigations, more recent studies have begun to examine the role of DTI (and in particular indices of diffusion anisotropy) as a potential marker to predict stroke outcome. 18,31,32,43,65 For example, Yang et al found differences in the ischemic time course of ADC and diffusion anisotropy between patients and within individual lesions.…”

Section: The Role Of Water Diffusion Changes In the Prediction Of Iscmentioning

confidence: 99%

“…18 The use of multiple MR parameters has the potential to provide a means of evaluating cerebral ischemia in a time-independent fashion, whereby the burden of ischemic tissue identification is borne by several different MR parameters over time. 22,28,[56][57][58][59][60][61][62][63][64][65] For example, Fig. 2 shows calculated maps for various MR parameters (including FA) at acute (3 h) and subacute (48 h) time points following 60 min of transient middle cerebral artery occlusion (MCAO) in the rat.…”

Section: The Role Of Water Diffusion Changes In the Prediction Of Iscmentioning

confidence: 99%

The role of diffusion tensor imaging in the evaluation of ischemic brain injury – a review

2002

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Water diffusion in brain tissue is affected by the presence of barriers to translational motion such as cell membranes and myelin fibers. The measured water apparent diffusion coefficient (ADC) value is therefore frequently anisotropic and varies depending upon the orientation of restricting barriers (such as white matter tracts) relative to the diffusion-sensitive-gradient direction. Anisotropic water diffusion can be specified using indices of diffusion anisotropy [e.g. standard deviation of the individual ADC values, fractional anisotropy (FA), lattice index (LI)], which are derived from measurements of the full diffusion tensor. The rotationally invariant nature of particular diffusion anisotropy indices (e.g. FA, LI) allows orientation-independent comparisons of these parameters between different subjects. Pathophysiological processes (such as cerebral ischemia) that modify the integrity of the tissue microstructure result in significant alterations in tissue anisotropy and make this metric a useful endpoint for characterizing the temporal evolution of the disease. Diffusion-tensor imaging (DTI) studies of both experimental and human stroke suggest that DTI may provide additional information about the evolution of the disease that is not available from diffusion-weighted MRI (DWI) alone. Acute reductions in the average diffusivity [ = ( 1 2 3 )/3 where 1 , 2 , and 3 are the eigenvalues of the diffusion tensor] following the onset of cerebral ischemia are often accompanied by increases in diffusion anisotropy. In the transition from acute to sub-acute and chronic stroke, renormalizes and subsequently increases whereas diffusion anisotropy measures (e.g. FA) decline and remained reduced in chronic infarcts. Overall isotropic ADC changes during infarct evolution have been observed to be greater in white matter (WM) than in gray matter (GM) lesions (although there have been conflicting reports on this issue) and GM lesions tend to renormalize prior to WM lesions as the infarct evolves. Ischemic WM exhibits a significant decrease in diffusion anisotropy (relative to normal WM) during ischemic evolution whereas that of ischemic GM remains statistically unchanged. Furthermore, the percentage decrease in ischemic WM is largely determined by reductions in 1 , the eigenvalue that coincides with the long axis of the WM fiber tract. Variations in unidirectional ADC or over the ischemic time course limit the usefulness of this parameter alone as a predictor of ischemic injury. Consequently, ADC information has been combined with that of other MR parameters (including DTI) to unambiguously stage and predict ischemic brain injury over its entire temporal evolution. Combined and diffusion anisotropy measurements have identified three phases of diffusion abnormality: (1) reduced and elevated anisotropy; (2) reduced and reduced anisotropy; and (3) elevated and reduced anisotropy. However, variations in the differential patterns of and diffusion anisotropy evolution have been obser...

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“…The acquisition time for a complete set of diffusion-weighted images (five images per slice) was 10 s. The diffusiongradient orientation was set from left to right for the chosen axial slice orientation. The apparent diffusion coefficients (ADC) were calculated for each pixel by fitting the logarithm of the signal intensity over the bvalues with a straight function [22]. The slope of the straight line represents the ADC for the particular pixel.…”

Section: Diffusion-weighted Imagingmentioning

confidence: 99%