Correction of Gradient Crosstalk and Optimization of Measurement Parameters in Diffusion MR Imaging

Eis, Manfred; Hoehn‐Berlage, Mathias

doi:10.1006/jmrb.1995.1082

Cited by 43 publications

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“…Quantitative ADC-, T 2 -, and T 1 -maps were calculated by fitting the data to monoexponential models using algorithms (22,23) written in IDL (Research Systems Inc., Boulder, CO). To minimize instrumental errors in the parameter map calculation, extensive data postprocessing, including correction for image-specific background noise and gradient cross-talk correction for the ADC calculation, was performed (22,24).…”

Section: Discussionmentioning

confidence: 99%

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Dynamic changes of ADC, perfusion, and NMR relaxation parameters in transient focal ischemia of rat brain

Dorsten

Oláh

Schwindt

et al. 2001

Magnetic Resonance in Med

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The potential of multiparametric MRI parameters for differentiating between reversibly and irreversibly damaged brain tissue was investigated in an experimental model of focal brain ischemia in the rat. The middle cerebral artery (MCA) was occluded by intraluminal suture insertion for 60 or 90 min, followed by 4.5 h of reperfusion. The apparent diffusion coefficient (ADC) of brain water, T 1 and T 2 relaxation times, and CBF i , an MRderived index of cerebral perfusion, were repeatedly measured and correlated with the outcome from the ischemic impact. A novel user-independent approach for segmentation of ADC maps into classes of increasing injury was introduced to define regions of interest (ROIs) in which these parameters were evaluated. MCA occlusion led to a graded decline of ADC, which corresponded with both the severity of flow reduction and an increase in T 1 and T 2 relaxation times. Removal of the suture led to a triphasic restitution of blood flow consisting of a fast initial rise, a secondary decline, and final normalization. Postischemic reperfusion led to a rise of ADC irrespective of the duration of ischemia. However, the quality of recovery declined with increasing severity of the ischemic impact. Throughout the observation time, T 1 and T 2 showed a continuous increase, the intensity of which correlated with the severity of ADC decline during ischemia. Particularly with longer ischemia time, elevated T 2 in combination with reduced ADC yielded a lower probability of recovery during recirculation, while intraischemic perfusion information contributed less to the prediction of outcome. In conclusion, the combination of MR parameters at the end of ischemia correlated with the probability of tissue recovery but did not permit reliable differentiation between reversibly and irreversibly damaged tissue. Magn Reson Med 47:97-104, 2002.

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Section: Discussionmentioning

confidence: 99%

“…To minimize instrumental errors in the parameter map calculation, extensive data postprocessing, including correction for image-specific background noise and gradient cross-talk correction for the ADC calculation, was performed (22,24).…”

Section: Discussionmentioning

confidence: 99%

Dynamic changes of ADC, perfusion, and NMR relaxation parameters in transient focal ischemia of rat brain

Dorsten

Oláh

Schwindt

et al. 2001

Magnetic Resonance in Med

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“…To improve temporal resolution, unweighted spin echoes (b 0/0 s/mm 2 ) were recorded intermittently and combined with the subsequently recorded weighted spin echoes (b0/1500 s/mm 2 ). Data postprocessing included correction for image-specific background noise [24]. Calculation of ADC was performed using the monoexponential intravoxel incoherent motion (IVIM) model [25].…”

Section: Nmr Measurementsmentioning

confidence: 99%

Time course of circulatory and metabolic recovery of cat brain after cardiac arrest assessed by perfusion- and diffusion-weighted imaging and MR-spectroscopy

et al. 2003

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Brain recovery after cardiac arrest (CA) was assessed in cats using arterial spin tagging perfusion-weighted imaging (PWI), diffusion-weighted imaging (DWI), and 1 H-spectroscopy ( 1 H-MRS). Cerebral reperfusion and metabolic recovery was monitored in the cortex and in basal ganglia for 6 h after cardiopulmonary resuscitation (CPR). Furthermore, the effects of an hypertonic/ hyperoncotic solution (7.5% NaCl/6% hydroxyl ethyl starch, HES) and a tissue-type plasminogen activator (TPA), applied during CPR, were assessed on brain recovery. CA and CPR were carried out in the MR scanner by remote control. CA for 15 Á/20 min was induced by electrical fibrillation of the heart, followed by CPR using a pneumatic vest. PWI after successful CPR revealed initial cerebral hyperperfusion followed by delayed hypoperfusion. Initial cerebral recirculation was improved after osmotic treatment. Osmotic and thrombolytic therapy were ineffective in ameliorating delayed hypoperfusion. Calculation of the apparent diffusion coefficient (ADC) from DWI demonstrated complete recovery of ion and water homeostasis in all animals. 1 H-MRS measurements of lactate suggested an extended preservation of post-ischaemic anaerobic metabolism after TPA treatment. The combination of noninvasive MR techniques is a powerful tool for the evaluation of therapeutical strategies on circulatory and metabolic cerebral recovery after experimental cerebral ischaemia. # 2003 Elsevier Ireland Ltd. All rights reserved.Keywords: Cardiac arrest; Cardiopulmonary resuscitation; Cerebral blood flow; Magnetic resonance techniques; Hypertonic solutions; Thrombolysis ResumoAvaliou-se a recuperação cerebral de gatos apó s paragem cardíaca (CA)..... com imagens de avaliação da perfusão (PWI) e imagens de avaliação da difusão (DWI) em espectrofotometria 1 H ( 1 H-MRS). A perfusão cerebral foi monitorizada no có rtex e nos gânglios da base durante seis horas a seguir à reanimação cardio-pulmonar (CPR). Avaliaram-se ainda os efeitos de uma solução hiperosmó tica e hiperoncó tica (NaCl hipertó nico 7.5% / hidroxi etil starch HES a 6%) e um activador tecidular do plasminogéneo (TPA), administrado durante a reanimação e avaliado na fase de recuperação. A CA e a RCP foram executadas, por controlo remoto, no scanner da ressonância magnética. A CA foi induzida, por descarga eléctrica, durante 15 Á/20 min, sendo a reanimação feita por colete pneumático. A PWI depois da CPR com sucesso evidenciou uma hiperperfusão cerebral inicial seguida de hipoperfusão. A recirculação cerebral inicial melhorou com a administração da solução osmó tica. O tratamento osmó tico e Abbreviations: ADC, apparent diffusion coefficient of water; ALS, advanced life support; CA, cardiac arrest; CBF, cerebral blood flow; CPR, cardiopulmonary resuscitation; Cr/PCr, creatine Á/phosphocreatine; DWI, diffusion-weighted imaging; HHS, hypertonic Á/hyperoncotic solution; 1 H-MRS, 1 H-proton spectroscopy; PWI, perfusion-weighted imaging; ROSC, return of spontaneous circulation; TPA, tissue-type plasminogen acti...

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“…This interaction between the imaging gradients and diffusion gradients is well known in standard diffusionweighted imaging (DWI) (7)(8)(9) and is generally referred to as "cross-term interaction." If those interactions are not accounted for in the experimental analysis, misinterpretation of the data can easily occur, particularly when the q-space experiments are performed using strong imaging gradients.…”

mentioning

confidence: 99%

“…For standard DWI experiments, Neeman et al (7) and Eis and Hoehn-Berlage (8) solved this problem for unidirectional diffusion measurements, whereas Mattiello et al (9) have done so for diffusion tensor measurements. However, if the q-space technique is to be implemented successfully in conjunction with imaging gradients, the cross-term interactions must also be evaluated for this sequence.…”

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confidence: 99%

Effects of, and corrections for, cross‐term interactions in q‐space MRI

Brihuega-Moreno

Heese

Tejos

et al. 2004

Magnetic Resonance in Med

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The present study assesses the effects of cross-term interactions between diffusion and imaging gradients in magnetic resonance imaging q-space analysis, and corrects for those effects for both spin echo and stimulated echo diffusionweighted sequences. These corrections are demonstrated experimentally in unrestricted media for water and theoretically by simulating the case of restricted diffusion in a sphere. By correcting for the cross-term interactions, large imaging gradients can be used without compromising the results. Ignoring cross-term interactions could lead to a misunderstanding of the q-space analysis; for instance, the microstructural size of the sample could be overestimated, or isotropic media could be misinterpreted as being anisotropic. In the early 1990s Callaghan (1) and Cory and Garroway (2) demonstrated that structural information too small to be detected by conventional nuclear magnetic resonance (NMR) methods can be inferred from the measurement of water diffusion. Their studies demonstrated that the echo attenuation in a spin echo sequence due to the effect of a pair of finite duration diffusion pulse field gradients, separated by a long diffusion time, could be related to the displacement probability of the observed spins following Fourier transformation (FT) of the echo intensity, E(q), with respect to the so-called "reciprocal spatial vector," q. This technique was termed q-space imaging, and it has since been used almost exclusively in bulk NMR spectroscopy. Recently, however, q-space imaging has been extended both to localized NMR spectroscopy (3) and to MRI (3-5).If additional magnetic field gradients (e.g., imaging gradients) are introduced into the diffusion sequence, however, these may contribute to the diffusion weighting, which in turn may translate into greater echo attenuation than would be expected from the diffusion gradients alone. This interaction between the imaging gradients and diffusion gradients is well known in standard diffusionweighted imaging (DWI) (7-9) and is generally referred to as "cross-term interaction." If those interactions are not accounted for in the experimental analysis, misinterpretation of the data can easily occur, particularly when the q-space experiments are performed using strong imaging gradients.For standard DWI experiments, Neeman et al. (7) and Eis and Hoehn-Berlage (8) solved this problem for unidirectional diffusion measurements, whereas Mattiello et al. (9) have done so for diffusion tensor measurements. However, if the q-space technique is to be implemented successfully in conjunction with imaging gradients, the cross-term interactions must also be evaluated for this sequence. In the present study, expressions for calculation of corrected qvalues, which account for cross-term interactions with imaging gradients, were derived and the practical implications of the imaging gradients in q-space imaging were examined. These corrections were determined for two sequences commonly used in q-space analysis, namely, the spin echo (10) and stimulat...

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Correction of Gradient Crosstalk and Optimization of Measurement Parameters in Diffusion MR Imaging

Cited by 43 publications

References 0 publications

Dynamic changes of ADC, perfusion, and NMR relaxation parameters in transient focal ischemia of rat brain

Dynamic changes of ADC, perfusion, and NMR relaxation parameters in transient focal ischemia of rat brain

Time course of circulatory and metabolic recovery of cat brain after cardiac arrest assessed by perfusion- and diffusion-weighted imaging and MR-spectroscopy

Effects of, and corrections for, cross‐term interactions in q‐space MRI

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