Analysis of variability of fractional anisotropy values at 3T using a novel diffusion tensor imaging phantom

We employed a novel diffusion tensor imaging phantom to study intra- and interscanner reproducibility on two 3T magnetic resonance (MR) scanners. Using a phantom containing thousands of hollow micron-size tubes in complex arrays, we performed two experiments using a b value of 1000 s/ms2 on two Siemens 3T Trio scanners. First, we performed 12-direction scans. Second, on one scanner, we performed two 64-direction protocols with different repetition times (TRs). We used a one-way analysis of variance to calculate differences between scanners and the Mann-Whitney U test to assess differences between 12-direction and 64-direction data. We calculated the coefficient of variation (CoV) for intrascanner and interscanner data. For 12-direction protocols, mean fractional anisotropy (FA) was 0.3003 for Scanner 1 (four scans) and 0.3094 for Scanner 2 (three scans). Lowest FA value on Scanner 1 was 2.56 standard deviations below the mean of Scanner 2. For 64-direction scans, mean FA was 0.2640 for 4000 ms TR and 0.2582 for 13,200 ms TR scans. For 12-direction scans, within-scanner CoV was 0.0326 for Scanner 1 and 0.0240 for Scanner 2; between-scanner CoV was 0.032. For 64-direction scans, CoV was 0.056 for TR 4000 ms and 0.0533 for TR 13,200 ms. The difference between median FA values of 12-direction and 64-direction scans was statistically significant ( p < 0.001). We found relatively good reproducibility on any single MR scanner. FA values from one scanner were sometimes significantly below the mean FA of another scanner, which has important implications for clinical use of DTI.

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Increased muscle fiber fractional anisotropy value using diffusion tensor imaging after compression without fiber injury

Acta Radiologica ◽

10.1177/02841851211058282 ◽

2021 ◽

pp. 028418512110582

Author(s):

Takumi Yokohama ◽

Motoyuki Iwasaki ◽

Daisuke Oura ◽

Sho Furuya ◽

Yoshimasa Niiya

Keyword(s):

Diffusion Tensor Imaging ◽

Fractional Anisotropy ◽

Muscle Tissue ◽

Diffusion Tensor ◽

Longitudinal Direction ◽

Diffusion Parameters ◽

Apparent Diffusion ◽

The Mean ◽

Magnetic Resonance Imaging Mri ◽

Age Range

Background Recent studies have indicated that injuries such as muscle tears modify the microstructural integrity of muscle, leading to substantial alterations in measured diffusion parameters. Therefore, the fractional anisotropy (FA) value decreases. However, we hypothesized that soft tissue, such as muscle tissue, undergoes reversible changes under conditions of compression without fiber injury. Purpose To evaluate the FA change due to compression in muscle tissue without fiber injury. Material and Methods Diffusion tensor imaging (DTI) was performed on both feet of 10 healthy volunteers (mean age = 35.0 ± 10.39 years; age range = 23–52 years) using a 3.0-T magnetic resonance imaging (MRI) scanner with an eight-channel phased array knee coil. An MRI-compatible sphygmomanometer was applied to the individuals’ lower legs and individuals were placed in a compressed state. Then, rest intervals of 5 min were set in re-rest state after compression. The FA value, apparent diffusion coefficient (ADC), and eigenvalues (λ1, λ2, λ3) of the gastrocnemius and soleus muscle were measured at each state. Results The mean FA values increased in all muscles in a compressed state, while the mean λ3 decreased. In all muscles, significant differences were found between the rest and compressed states in terms of mean FA and λ3 ( P < 0.0001). Conclusion We confirmed the reversibility of the DTI metrics, which suggests that there was no muscle injury during this study. In cases of compression without fiber injury, the FA value increases, because fibers are strongly aligned in the longitudinal direction.

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DIFFUSION TENSOR TRACTOGRAPHY

Neurosurgery ◽

10.1227/01.neu.0000325259.95571.20 ◽

2008 ◽

Vol 63 (3) ◽

pp. 452-459 ◽

Cited By ~ 6

Author(s):

Wai Hoe Ng ◽

Dennis Lai-Hong Cheong ◽

Kathleen Joy Khu ◽

Govidasamy Venkatesh ◽

Yee Kong Ng ◽

...

Keyword(s):

Diffusion Tensor Imaging ◽

Magnetic Resonance ◽

Fractional Anisotropy ◽

Corticospinal Tract ◽

Tumor Volume ◽

Diffusion Tensor ◽

Diffusion Tensor Tractography ◽

Significant Difference ◽

Fiber Number ◽

And Diffusion

ABSTRACT OBJECTIVE Benign extracerebral lesions such as meningiomas may cause hemiparesis by compression and deviation without infiltrating the white matter. We used magnetic resonance diffusion tensor imaging and diffusion tensor tractography to investigate the effects of benign extracerebral lesions on the corticospinal tract (CST). METHODS Thirteen patients with extracerebral lesions (11 benign meningiomas and 2 benign cysts) underwent magnetic resonance diffusion tensor imaging and diffusion tensor tractography of the CST using fiber assignment by continuous tractography. The CST was reconstructed and assessed by comparing the ipsilateral and unaffected contralateral fibers. The tumor volume, relative fractional anisotropy, fiber deviation, relative fiber number, and relative fiber per voxel were compared between patients without and with temporary presurgical hemiparesis. RESULTS Seven patients without hemiparesis and five patients with temporary hemiparesis were analyzed; one patient had permanent weakness and was excluded from analysis. There was no significant difference in the tumor volume, relative fractional anisotropy, presence of cerebral edema, or CST deviation between groups. In patients with temporary hemiparesis, the median relative fiber number (mean, 0.35 ± 0.32) and relative fiber per voxel (mean, 0.49 ± 0.14) were significantly reduced compared with patients without hemiparesis (0.92 ± 0.55, P = 0.04; and 0.96 ± 0.28, P < 0.01, respectively). CONCLUSION In patients with benign extracerebral lesions, reduction in fiber number and fiber per voxel, but not fiber deviation, correlated with temporary hemiparesis. Clinical recovery was possible even if the CST fibers detected by diffusion tensor tractography were reduced by benign extracerebral lesions.

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Fractional Anisotropy Levels Derived From Diffusion Tensor Imaging in Cervical Syringomyelia

Neurosurgery ◽

10.1227/neu.0b013e3181ecfcdd ◽

2010 ◽

Vol 67 (4) ◽

pp. 901-905 ◽

Cited By ~ 11

Author(s):

Florian Roser ◽

Florian Ebner ◽

Gottlieb Maier ◽

Marcos Tatagiba ◽

Thomas Nägele ◽

...

Keyword(s):

Magnetic Resonance Imaging ◽

Diffusion Tensor Imaging ◽

White Matter ◽

Magnetic Resonance ◽

Evoked Potentials ◽

Fractional Anisotropy ◽

Diffusion Tensor ◽

Motor Evoked Potentials ◽

Neurological Deficits ◽

Resonance Imaging

Abstract BACKGROUND: Syringomyelia can result in major functional disability. Conventional imaging techniques frequently fail to detect the underlying cause of syringomyelia. The prediction as to whether syringomyelia might lead to neurological deficits is still challenging. OBJECTIVE: We hypothesized that fractional anisotropy (FA) derived from diffusion tensor imaging (DTI) is a parameter to detect dynamic forms of syringomyelia. METHODS: Six patients with cervical syringomyelia, all comparable in size, shape, and location, were examined, along with 2 volunteers. Patients underwent electrophysiological recordings (somatosensory evoked potentials, motor evoked potentials, silent periods). Magnetic resonance imaging (1.5 T) was performed with a 6-element spine coil. Anatomic images were acquired with a 3-dimensional, constructive interference in steady-state sequence, and DTI with an echo-planar imaging sequence (5-mm thickness, b value 800 s/mm2) using the generalized autocalibrating partially parallel acquisitions technique. The positions were centered on the syrinx in the volunteers between the C2 and Th1. DTI data were interpolated to a spatial resolution of 0.5 mm. After calculation of a diffusion tensor in each pixel, an FA map was calculated and profiles of the FA values across the spinal cord were calculated in all slices. RESULTS: FA values were lower at the level of all examined syrinxes and reached normal values beyond them. Electrophysiological results correlated with the decrease in FA value. There were no presyrinx changes in the white matter tracts in terms of signs of FA changes beneath the syrinx. CONCLUSION: DTI of syringomyelia can demonstrate white matter fiber tracts around and beyond the syrinx consistent with electrophysiological values. DTI of the cervical spine can provide quantitative information about the pathological characteristics beyond the abnormalities visible on magnetic resonance imaging.

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Assessment of lumbar disc herniaton using fractional anisotropy in diffusion tensor imaging along with conventional T2-weighted imaging

The Neuroradiology Journal ◽

10.1177/1971400919891288 ◽

2019 ◽

Vol 33 (1) ◽

pp. 24-31

Author(s):

Marco Perri ◽

Marialuisa D’Elia ◽

Giulia Castorani ◽

Rosario Francesco Balzano ◽

Annamaria Pennelli ◽

...

Keyword(s):

Magnetic Resonance Imaging ◽

Diffusion Tensor Imaging ◽

Magnetic Resonance ◽

Fractional Anisotropy ◽

Lumbar Disc Herniation ◽

Diffusion Tensor ◽

Lumbar Disc ◽

Study Group ◽

Conventional Magnetic Resonance Imaging ◽

Resonance Imaging

Objective To assess the usefulness of diffusion tensor imaging and its fractional anisotropy map along with conventional T2-weighted imaging in evaluating the anisotropic water diffusion variations of annulus fibres involved in herniation disc pathology. Materials and methods Seventy-five patients with previous medical ethics committee approval and informed consent experiencing low back pain were selected for this prospective randomised blinded trial. Lumbar disc fractional anisotropy maps were obtained acquiring diffusion tensor sequences on a 3T machine. The matrix of nucleus pulposus and structures of annulus fibres were analysed using fractional anisotropy textural features to highlight any presence of lumbar disc herniation. Observer variability and reliability between two neuroradiologists were evaluated. The χ2 test, two-tailed t test and linear regression analysis were used to focus differences in patients’ demographic data and magnetic resonance imaging findings. Results Annular fissures with extrusions were identified using diffusion tensor imaging in 10 out of 17 discs (study group) previously assessed as bulging discs using conventional magnetic resonance imaging. Eighteen extrusions out of 39 (study group) disc levels were identified on diffusion tensor imaging compared to eight extrusions highlighted on T2-weighted imaging ( P < 0.01). All eight (study group) disc extrusions evaluated on T2-weighted imaging showed annular fissures on diffusion tensor imaging. Seven out of 14 (study group) protrusions highlighted on T2-weighted imaging had no annular fissures on diffusion tensor imaging; thirty-six disc levels in the control group had no evidence of annular fissures on diffusion tensor imaging ( P > 0.01). Conclusions The addition of diffusion tensor imaging sequences and fractional anisotropy mapping to a conventional magnetic resonance imaging protocol could be useful in detecting annular fissures and lumbar disc herniation.

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Consistency of Fractional Anisotropy Values Using Different Combinations of b-Value and Time of Echo (TE) in Diffusion Tensor Imaging of Normal Brain White Matter

JOURNAL FOR CLINICAL AND DIAGNOSTIC RESEARCH ◽

10.7860/jcdr/2018/38089.12315 ◽

2018 ◽

Author(s):

Rahul P Kotian ◽

K Prakashini ◽

Sreekumaran Nair ◽

M Satish Babu

Keyword(s):

Diffusion Tensor Imaging ◽

White Matter ◽

Fractional Anisotropy ◽

Diffusion Tensor ◽

B Value ◽

Normal Brain ◽

Brain White Matter

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Diffusion Tensor Imaging and Colored Fractional Anisotropy Mapping of the Ventralis Intermedius Nucleus of the Thalamus

Neurosurgery ◽

10.1227/neu.0b013e3182296a42 ◽

2011 ◽

Vol 69 (5) ◽

pp. 1124-1130 ◽

Cited By ~ 27

Author(s):

Mark Sedrak ◽

Alessandra Gorgulho ◽

Andrew Frew ◽

Eric Behnke ◽

Antonio DeSalles ◽

...

Keyword(s):

Magnetic Resonance Imaging ◽

Diffusion Tensor Imaging ◽

White Matter ◽

Magnetic Resonance ◽

Fractional Anisotropy ◽

Diffusion Tensor ◽

Patient Specific ◽

Superior Cerebellar Peduncle ◽

Resonance Imaging ◽

Neurosurgical Planning

Abstract BACKGROUND The ventralis intermedius (VIM) nucleus of the thalamus is the primary surgical target for treatment of tremor. Most centers rely on indirect targeting based on atlas-defined coordinates rather than patient-specific anatomy, making intraoperative physiological mapping critical. Detailed identification of this target based on patient-specific anatomic features can help optimize the surgical treatment of tremor. OBJECTIVE To study colored fractional anisotropic images and diffusion tensor imaging (DTI) tractography to identify characteristic magnetic resonance appearances of the VIM nucleus. METHODS Four patients undergoing stereotactic surgery for essential tremor (ET) were retrospectively studied with analysis of magnetic resonance imaging-based colored fractional anisotropy (FA) images and fiber tractography. All were scanned with a 1.5-T magnetic resonance imaging unit, and all sequences were obtained before frame placement. Because the goal of this study was to identify the DTI characteristics of physiologically defined VIM nucleus, we selected and studied patients who had undergone DTI and had efficacious tremor control with intraoperative microlesioning effect and tremor reduction with less than 2.0-V stimulation. RESULTS Analysis of color FA maps, which graphically illustrate fiber directionality, revealed consistent anatomic patterns. The region of the VIM nucleus can be seen as an intermediate region where there is a characteristic transition of color. Presumptive VIM nucleus interconnectivity with sensorimotor cortex and cerebellum was identified via the internal capsule and the superior cerebellar peduncle, respectively. FA maps could also be used to distinguish segments of gray matter, white matter, and gray-white matter boundaries. CONCLUSION Analysis of DTI and FA maps on widely available 1.5-T magnetic resonance imaging yields clear identification of various structures key to neurosurgical targeting. Prospective evaluation of integrating DTI into neurosurgical planning may be warranted.

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Longitudinal Magnetic Resonance Spectroscopy and Diffusion Tensor Imaging in Sheep (Ovis aries) With Quinolinic Acid Lesions of the Striatum: Time-Dependent Recovery of N-Acetylaspartate and Fractional Anisotropy

Journal of Neuropathology & Experimental Neurology ◽

10.1093/jnen/nlaa053 ◽

2020 ◽

Vol 79 (10) ◽

pp. 1084-1092

Author(s):

Adam B O’Connell ◽

Timothy R Kuchel ◽

Sunthara R Perumal ◽

Victoria Sherwood ◽

Daniel Neumann ◽

...

Keyword(s):

Diffusion Tensor Imaging ◽

Magnetic Resonance ◽

Magnetic Resonance Spectroscopy ◽

Fractional Anisotropy ◽

Quinolinic Acid ◽

Diffusion Tensor ◽

Ovis Aries ◽

Resonance Spectroscopy ◽

Neuronal Marker ◽

And Diffusion

Abstract We created an excitotoxic striatal lesion model of Huntington disease (HD) in sheep, using the N-methyl-d-aspartate receptor agonist, quinolinic acid (QA). Sixteen sheep received a bolus infusion of QA (75 µL, 180 mM) or saline, first into the left and then (4 weeks later) into the right striatum. Magnetic resonance spectroscopy (MRS) and diffusion tensor imaging (DTI) of the striata were performed. Metabolite concentrations and fractional anisotropy (FA) were measured at baseline, acutely (1 week after each surgery) and chronically (5 weeks or greater after the surgeries). There was a significant decrease in the neuronal marker N-acetylaspartate (NAA) and in FA in acutely lesioned striata of the QA-lesioned sheep, followed by a recovery of NAA and FA in the chronically lesioned striata. NAA level changes indicate acute death and/or impairment of neurons immediately after surgery, with recovery of reversibly impaired neurons over time. The change in FA values of the QA-lesioned striata is consistent with acute structural disruption, followed by re-organization and glial cell infiltration with time. Our study demonstrates that MRS and DTI changes in QA-sheep are consistent with HD-like pathology shown in other model species and that the MR investigations can be performed in sheep using a clinically relevant human 3T MRI scanner.

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Magnetic Resonance Imaging with Diffusion Tractography in Assessment of Cerebral Lesions Affecting the Optic Radiations

Journal of Advances in Medicine and Medical Research ◽

10.9734/jammr/2021/v33i1731044 ◽

2021 ◽

pp. 192-201

Author(s):

Nayera Mohamed El-Ganainy ◽

Samah Ahmed Radwan ◽

Ehab Mohamed El-Gamal ◽

Mohamed Fouad Sherif

Keyword(s):

Magnetic Resonance Imaging ◽

Diffusion Tensor Imaging ◽

Magnetic Resonance ◽

Fractional Anisotropy ◽

Diffusion Tensor ◽

P Value ◽

Resonance Imaging ◽

Cerebral Lesions ◽

Fiber Tracts ◽

Optic Radiations

Background: The combination of Functional magnetic resonance imaging with Diffusion Tensor Imaging has proven scientific and clinical relevance. By measuring the directed provides complementary information on white matter architecture, i.e., on the course and integrity of functionally important white matter tracts. In the diffusion of protons along myelinated fibers, Diffusion Tensor neuroimaging research is mainly applied to study the human brain's structural connectivity, whereas diffusion tensor tractography is often also employed for clinical applications. Diffusion Tensor Imaging measurements can be obtained together with Functional magnetic resonance imaging in the same scanning session, which gives an even more complete picture of each patient's brain. This study aimed to assess cerebral lesions affecting optic radiations by magnetic resonance imaging with diffusion tensor imaging tractography. Methods: Our prospective study was conducted on 30 cases ages ranged from 17-83 years, 10 of them were normal and considered as the control group and 20 patients were presented with clinical neurological symptoms and signs associated with visual abnormalities. Results: There is a significant difference between the Fractional anisotropy difference and difference ratio between the two groups with a p-value of 0.016 and 0.017 respectively. There was a strong significant positive correlation between Fractional anisotropy difference ratio (%) and tractography; r = 0.716 (95% confidence interval: 0.470 - 0.858) and p-value <0.001. We correlated the pathological types with different patterns of tractography. optic radiations fiber tracts were displaced in 83.3% of benign tumors and infiltrated in 16.3%. while in malignant tumors optic radiations fiber tracts were displaced in 75%, infiltrated in 12.5%, and disrupted in 25%. There is no "gold standard" for in vivo tractography. Diffusion Tensor Imaging is the only method that permits the calculation and visualization of fiber tracts trajectories in vivo. Conclusions: Diffusion Tensor Imaging tractography is clinically feasible and provides useful information regarding the site of optic radiations and their affection by different brain lesions also, surgical strategy for lesions located in eloquent visual areas. Also, there was a strong significant positive correlation between Fractional anisotropy difference ratio (%) and tractography distribution. Also, probabilistic multifiber tractography applied to diffusion Magnetic resonance imaging data acquired at 3T may be better as it can cope with crossing and kissing fibers than deterministic models because it allows many more possible local pathway orientations for each Diffusion Tensor Imaging sample point.

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