Diffusion Fractional Anisotropy Research Articles

Examining the neurostructural architecture of intelligence: The Lothian Birth Cohort 1936 study

Examining underlying neurostructural correlates of specific cognitive abilities is practically and theoretically complicated by the existence of the positive manifold (all cognitive tests positively correlate): if a brain structure is associated with a cognitive task, how much of this is uniquely related to the cognitive domain, and how much is due to covariance with all other tests across domains (captured by general cognitive functioning, also known as general intelligence, or ‘g’)? We quantitatively address this question by examining associations between brain structural and diffusion MRI measures (global tissue volumes, white matter hyperintensities, global white matter diffusion fractional anisotropy and mean diffusivity, and FreeSurfer processed vertex-wise cortical volumes, smoothed at 20mm fwhm) with g and cognitive domains (processing speed, crystallised ability, memory, visuospatial ability). The cognitive domains were modelled using confirmatory factor analysis to derive both hierarchical and bifactor solutions using 13 cognitive tests in 697 participants from the Lothian Birth Cohort 1936 study (mean age 72.5 years; SD = .7). Associations between the extracted cognitive factor scores for each domain and g were computed for each brain measure covarying for age, sex and intracranial volume, and corrected for false discovery rate.There were a range of significant associations between cognitive domains and global MRI brain structural measures (r range .008 to .269, p < .05). Regions implicated by vertex-wise regional cortical volume included a widespread number of medial and lateral areas of the frontal, temporal and parietal lobes. However, at both global and regional level, much of the domain-MRI associations were shared (statistically accounted for by g). Removing g-related variance from cognitive domains attenuated association magnitudes with global brain MRI measures by 27.9–59.7% (M = 46.2%), with only processing speed retaining all significant associations. At the regional cortical level, g appeared to account for the majority (range 22.1–88.4%; M = 52.8% across cognitive domains) of regional domain-specific associations. Crystallised and memory domains had almost no unique cortical correlates, whereas processing speed and visuospatial ability retained limited cortical volumetric associations. The greatest spatial overlaps across cognitive domains (as denoted by g) were present in the medial and lateral temporal, lateral parietal and lateral frontal areas.

Diffusion MRI Metrics Characterize Postoperative Clinical Outcomes After Surgery for Cervical Spondylotic Myelopathy.

Advanced diffusion-weighted MRI (DWI) modeling, such as diffusion tensor imaging (DTI) and diffusion basis spectrum imaging (DBSI), may help guide rehabilitation strategies after surgical decompression for cervical spondylotic myelopathy (CSM). Currently, however, postoperative DWI is difficult to interpret, owing to signal distortions from spinal instrumentation. Therefore, we examined the relationship between postoperative DTI/DBSI-extracted from the rostral C3 spinal level-and clinical outcome measures at 2-year follow-up after decompressive surgery for CSM. Fifty patients with CSM underwent complete clinical and DWI evaluation-followed by DTI/DBSI analysis-at baseline and 2-year follow-up. Clinical outcomes included the modified Japanese Orthopedic Association score and comprehensive patient-reported outcomes. DTI metrics included apparent diffusion coefficient, fractional anisotropy, axial diffusivity, and radial diffusivity. DBSI metrics evaluated white matter tracts through fractional anisotropy, fiber fraction, axial diffusivity, and radial diffusivity as well as extra-axonal pathology through restricted and nonrestricted fraction. Cross-sectional Spearman's correlations were used to compare postoperative DTI/DBSI metrics with clinical outcomes. Twenty-seven patients with CSM, including 15, 7, and 5 with mild, moderate, and severe disease, respectively, possessed complete baseline and postoperative DWI scans. At 2-year follow-up, there were 10 significant correlations among postoperative DBSI metrics and postoperative clinical outcomes compared with 3 among postoperative DTI metrics. Of the 13 significant correlations, 7 involved the neck disability index (NDI). The strongest relationships were between DBSI axial diffusivity and NDI (r = 0.60, P < .001), DBSI fiber fraction and NDI (rs = -0.58, P < .001), and DBSI restricted fraction and NDI (rs = 0.56, P < .001). The weakest correlation was between DTI apparent diffusion coefficient and NDI (r = 0.35, P = .02). Quantitative measures of spinal cord microstructure after surgery correlate with postoperative neurofunctional status, quality of life, and pain/disability at 2 years after decompressive surgery for CSM. In particular, DBSI metrics may serve as meaningful biomarkers for postoperative disease severity for patients with CSM.

A site-wise reliability analysis of the ABCD diffusion fractional anisotropy and cortical thickness: impact of scanner platforms.

The Adolescent Brain and Cognitive Development (ABCD) project is the largest study of adolescent brain development. ABCD longitudinally tracks 11,868 participants aged 9-10 years from 21 sites using standardized protocols for multi-site MRI data collection and analysis. While the multi-site and multi-scanner study design enhances the robustness and generalizability of analysis results, it may also introduce non-biological variances including scanner-related variations, subject motion, and deviations from protocols. ABCD imaging data were collected biennially within a period of ongoing maturation in cortical thickness and integrity of cerebral white matter. These changes can bias the classical test-retest methodologies, such as intraclass correlation coefficients (ICC). We developed a site-wise adaptive ICC (AICC) to evaluate the reliability of imaging-derived phenotypes while accounting for ongoing brain development. AICC iteratively estimates the population-level age-related brain development trajectory using a weighted mixed model and updates age-corrected site-wise reliability until convergence. We evaluated the test-retest reliability of regional fractional anisotropy (FA) measures from diffusion tensor imaging and cortical thickness (CT) from structural MRI data for each site. The mean AICC for 20 FA tracts across sites was 0.61±0.19, lower than the mean AICC for CT in 34 regions across sites, 0.76±0.12. Remarkably, sites using Siemens scanners consistently showed significantly higher AICC values compared to those using GE/Philips scanners for both FA (AICC=0.71±0.12 vs 0.46±0.17, p<0.001) and CT (AICC=0.80±0.10 vs 0.69±0.11, p<0.001). These findings demonstrate site-and-scanner related variations in data quality and underscore the necessity for meticulous data curation in subsequent association analyses.

Diffusion tensor imaging and fiber tractography of the normal epididymis.

To evaluate the feasibility of diffusion tensor imaging (DTI) and fiber tractography (FT) of the normal epididymis and to determine normative apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values. Twenty-eight healthy volunteers underwent MRI of the scrotum, including DTI on a 3.0T system. For each anatomic part of the epididymis (head, body and tail) free-hand regions of interest were drawn and the mean ADC and FA were measured by two radiologists in consensus. Parametric statistical tests were used to determine intersubject differences in ADC and FA between the anatomic parts of each normal epididymis and between bilateral epididymides. Fiber tracts of the epididymis were reconstructed using the MR Diffusion tool. The mean ADC and FA of the normal epididymis was 1.31 × 10-3 mm2/s and 0.20, respectively. No differences in ADC (p = 0.736) and FA (p = 0.628) between the anatomic parts of each normal epididymis were found. Differences (p = 0.020) were observed in FA of the body between the right and the left epididymis. FT showed the fiber tracts of the normal epididymis. Main study's limitations include the following: small number of participants with narrow age range, absence of histologic confirmation and lack of quantitative assessment of the FT reconstructions. DTI and FT of the normal epididymis is feasible and allow the noninvasive assessment of the structural and geometric organization of the organ.

Diffusion Tensor Tractography in Patient with Cervical Spondylosis and Correlation with Clinical Findings

Introduction: Diffusion tensor imaging is a non-invasive advanced method that provides information on white matter microstructural integrity. Fractional anisotropy and apparent diffusion coefficient have been used to quantify the degree of axonal damage and demyelination. The study aims to assess the role of diffusion tensor parameters in detecting early myelopathic changes and correlate them with clinical findings. Methods: This cross-sectional prospective study including 60 patients with clinical history of cervical myelopathy was carried out at the Department of Radiology from June 2021 to July 2022. Nurick score was used to assess the severity clinically and diffusion tensor images of the cervical spine were obtained using 3 Tesla MRI. These diffusion tensor values at the level of maximum stenosis were compared with those of the non-stenotic level. A correlation between the diffusion tensor parameters and clinical Nurick score was done. Results: The fractional anisotropy values were significantly lower (0.51 ± 0.14 vs 0.76 ± 0.47) and apparent diffusion coefficient values were significantly higher (1.20 ± 0.20 vs 1.04 ± 0.12) at the level of maximum stenosis compared with non-stenotic levels. There was a moderate positive and strong negative correlation between the apparent diffusion coefficient and fractional anisotropy values with the Nurick score. Conclusions: A significant reduction in the fractional anisotropy and an increase in apparent diffusion coefficient values at the level of stenosis was observed in individuals without a high T2 signal within the cord. Thus, these parameters might have a potential role in the early diagnosis of cervical spondylotic myelopathy

Diffusion tensor imaging combined with the dual-echo steady-state (DESS) protocol for the evaluation of the median nerve in the carpal tunnel: A preliminary study.

Carpal tunnel syndrome (CTS) is diagnosed based on neurological, electrophysiology, and radiological findings. Due to the technical development of magnetic resonance imaging (MRI), the median nerve is evaluated with several MRI protocols. However, diffusion tensor imaging (DTI) combined with a dual-echo steady-state (DESS) protocol is not frequently used to evaluate the median nerve of CTS. This study aimed to evaluate the median nerve in the carpal tunnel using DTI combined with a DESS protocol. Five healthy volunteers and seven patients with CTS were enrolled. The patients underwent MRI for CTS pre- and post-operatively. The median nerve was evaluated using a 3-T MRI scanner. The parameters of the DESS protocol were as follows: Repetition time (TR)/echo time (TE) = 10.83/3.32 ms, slice thickness = 0.45 mm, field of view (FoV) = 350 × 253 × 350 mm, and 3D voxel size = 0.5 × 0.5 ×0.4 mm. The parameters of the DTI sequence were as follows: TR/TE = 4000/86 ms, slice thickness = 3 mm, FoV = 160 × 993 × 90 mm, 3D voxel size = 1.2 × 1.2 ×3.0 mm, and b value = 0.1000 s/mm2. The apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values of the median nerve were statistically analyzed. Statistical significance was set at P< 0.05. The FA value of healthy volunteers was 0.576 ± 0.058, while those of the patients were 0.357 ± 0.094 and 0.395 ± 0.062 pre-and post-operatively, respectively. Statistically significant differences were identified between the FA values of healthy volunteers and pre-operative/post-operative patients. The ADC values of healthy volunteers and pre-operative patients were 0.931 ± 0.096 and 1.26 ± 0.282 (10-3 mm2/s), respectively (P< 0.05). This MRI protocol may be useful for evaluating the median nerve in the carpal tunnel.

Feasibility study to assess lesion repair in relapsing-remitting multiple sclerosis: A randomized controlled pilot clinical trial of domperidone add-on treatment

BackgroundIdentification of therapies to promote repair in multiple sclerosis is challenged by the lack of an accepted trial model and associated outcome measures. The goal of this study was to determine the feasibility of a new trial model that enrolls disease modifying therapy (DMT)-treated relapsing-remitting multiple sclerosis (RRMS) participants who have enhancing lesions on clinically indicated brain MRI, and to explore estimates of lesion repair using MRI. MethodsThis was a single site randomized controlled clinical trial. Recruitment took place between November 2015 and January 2019, with final follow-up in February 2019. DMT-treated RRMS participants aged 18–60 years with at least one gadolinium-enhancing lesion on clinically indicated brain MRI were included. Participants were randomized 2:1 to oral domperidone add-on 10-mg three times daily for 16 weeks or no add-on treatment (control). The primary outcomes were feasibility of the model pre-defined as recruitment of 24 participants within 36 months with a 79 % completion rate, and MRI outcomes of lesion repair measured at 16 and 32 weeks using texture analysis, magnetization transfer imaging (MTI), and diffusion tensor imaging (DTI). The impact of domperidone on serum prolactin at 6 and 16 weeks was also evaluated. ResultsOf 237 RRMS participants screened, 17 (14 women) were randomized: 12 to domperidone add-on and 5 to control. All completed the study. Median (range) age was 38.9 (26.7–55.9) years; EDSS was 1.5 (1.0–3.5); and disease duration was 12.9 (2.9–23.3) years. Both groups showed improvement in MRI texture and diffusion fractional anisotropy (FA) at 32 weeks, and the domperidone group demonstrated additional recovery at 16 weeks in both texture and FA. There was no significant group difference in any MRI outcome. Of the 12 domperidone participants, 7 had ≥4x higher serum prolactin than normal. There were no serious adverse events. ConclusionThe recruitment target was not met and therefore the trial model was not feasible despite a full completion rate. The imaging techniques performed well, especially MRI texture analysis, suggesting the sample size being sufficient for estimating lesion repair. The main challenge of this trial model may be recruiting gadolinium-enhancing lesions in DMT-treated RRMS participants. Prolactin is safe and may hold promise as a remyelination therapy. Trial registrationClinicalTrials.gov Identifier: NCT02493049.

Study on the Relationship Between MRI Functional Imaging and Multiple Immunohistochemical Features of Glioma: A Noninvasive and More Precise Glioma Management.

To investigate the performance of diffusion-tensor imaging (DTI) and hydrogen proton magnetic resonance spectroscopy (1H-MRS) parameters in predicting the immunohistochemistry (IHC) biomarkers of glioma. Patients with glioma confirmed by pathology from March 2015 to September 2019 were analyzed, the preoperative DTI and 1H-MRS images were collected, apparent diffusion coefficient (ADC) and fractional anisotropy (FA), in the lesion area were measured, the relative values relative ADC (rADC) and relative FA (rFA) were obtained by the ratio of them in the lesion area to the contralateral normal area. The peak of each metabolite in the lesion area of 1H-MRS image: N-acetylaspartate (NAA), choline (Cho), and creatine (Cr), and metabolite ratio: NAA/Cho, NAA/(Cho + Cr) were selected and calculated. The preoperative IHC data were collected including CD34, Ki-67, p53, S-100, syn, vimentin, NeuN, Nestin, and glial fibrillary acidic protein. One predicting parameter of DTI was screened, the rADC of the Ki-67 positive group was lower than that of the negative group. Two parameters of 1H-MRS were found to have significant reference values for glioma grades, the NAA and Cr decreased as the grade of glioma increased, moreover, Ki-67 Li was negatively correlated with NAA and Cr. NAA and Cr have potential application value in predicting glioma grades and tumor proliferation activity. Only rADC has predictive value for Ki-67 expression among DTI parameters.

Neurite‐based white matter alterations in MAPT mutation carriers: A multi‐shell diffusion MRI study in the ALLFTD consortium

AbstractBackgroundWe aimed to assess axonal integrity in MAPT mutation carriers and early white matter (WM) neurodegeneration in asymptomatic carriers using traditional diffusion tensor imaging (DTI) measurements, i.e., fractional anisotropy (FA) and mean diffusivity (MD), and neurite orientation dispersion and density imaging (NODDI).MethodWe included available multi‐shell diffusion MRI data from 21 MAPT mutation carriers (16 asymptomatic; 5 symptomatic) and 31 non‐carrier family members as controls from the ALLFTD consortium. We used linear mixed‐effect models to assess WM abnormalities measured with FA and MD, neurite density index (NDI) and orientation dispersion index (ODI), combined across hemispheres. Separate models were conducted in all MAPT mutation carriers relative to controls while accounting for relatedness and age, then in symptomatic and asymptomatic carriers relative to controls. ComBat was used to harmonize data across sites.ResultIn models contrasting all MAPT carriers versus controls, WM alterations involved the cingulum bundle (FA, ODI), fronto‐temporal, entorhinal (FA, MD, NDI), and the inferior temporal WM (FA) after correcting for multiple comparisons (Fig. 1). In models contrasting symptomatic and asymptomatic MAPT carriers versus controls, symptomatic carriers had widespread involvement of the fronto‐temporal WM including the cingulum (FA, ODI), entorhinal (MD, FA, NDI), amygdala (MD, NDI) and inferior temporal (FA) areas after correcting for multiple comparisons. Asymptomatic carriers showed higher entorhinal MD and lower inferior temporal and cingulum FA relative to controls, and a more widespread pattern of higher ODI involved the medial temporal, superior temporal and occipital WM as well as long association and projection fibers including the internal capsule, cingulate bundle and fronto‐occipital fasciculi, although they were not statistically significant after correction for multiple comparisons.ConclusionTraditional DTI and novel NODDI measurements revealed some extent of overlap as well as divergences in patterns of WM abnormalities, indicating axonal loss is a feature of neurodegeneration in MAPT mutation carriers. Our results suggest that traditional DTI and novel NODDI measurements may have different sensitivities to WM alterations in MAPT mutation carriers, and that axon‐based metrics, particularly ODI measurements, may be more sensitive to the early WM involvement during the asymptomatic stage of the disease.

Advanced muscle imaging in adolescent elite rowers utilizing diffusion tensor imaging: Association of imaging findings with stroke typology.

Muscular overuse injuries are a common health issue in elite athletes. Changes in the muscular microenvironment can be depicted by Diffusion Tensor Imaging (DTI). We hypothesize that the biomechanics of different stroke typologies plays a role in muscle injury and tested our hypothesis by magnetic resonance imaging (MRI) examination of the lumbar spine muscles of adolescent rowers utilizing DTI. Twenty-two male elite rowers (12 sweep, 10 scull rowers) with a mean age of 15.8 ± 1.2 years underwent 3-Tesla MRI of the lumbar spine 6 hours after cessation of training. Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) were calculated for the erector spinae and multifidus muscle. Student's t-test was used to test differences of DTI parameters between sweep and scull rowers and a Pearson correlation was utilized to correlate the parameters to training volume. ADC values in the erector spinae and multifidus muscle were significantly higher (p = 0.039) and FA values significantly lower (p < 0.001) in sweep rowers compared to scull rowers. There was no significant association between DTI parameters and training volume (r ≤ -0.459, p ≥ 0.074). Our DTI results show that lumbar spine muscle diffusivity is higher in sweep rowers than in scull rowers. Altered muscle diffusivity is suggestive of microscopic tissue disruption and might be attributable to biomechanical differences between stroke typologies.

4 Interactions of Inflammation and Psychosocial Stress on White Matter Integrity Over Time in Older Black Adults

Objective:Higher levels of inflammation are associated with risk factors for Alzheimer’s disease and related dementias (ADRD) in older Black adults including psychosocial stressors (e.g., discrimination and early life adversity) and white matter alterations. Yet, limited work has investigated these risk factors together in a longitudinal neuroimaging study, despite the well-known ADRD disparity in older Black adults. Using data from the Minority Aging Research Study and African American Clinical Core of the Rush Alzheimer’s Disease Center, we examined interactions of psychosocial stressors and change in inflammation on changes in white matter integrity as measured via diffusion tensor imaging (DTI).Participants and Methods:Older Black adults (n=102) without known dementia at baseline (age=75.8±6.1 years; 87.3% female; education=15.4±2.7 years) completed blood draws at two time points (follow-up=2.4±0.7 years), neuroimaging at two or more time points (follow-up=3.7±1.8 years), and psychosocial questionnaires at one time point coinciding with the first blood draw/neuroimaging. Blood serum was assayed using highly-sensitive multiplexed sandwich ELISA for interleukin-6, c-reactive protein (CRP), and tumor necrosis factor-alpha (TNF-a) and a change score was calculated for each inflammatory marker (T2 - T1). The Williams Everyday Discrimination Scale quantified experiences of discrimination in all participants and a 16-item questionnaire of emotional and physical trauma from age 0-18 assessed early life adversity in a participant subset (n=63). DTI-derived tract-based spatial statistics (TBSS) slope change measures for trace of the diffusion tensor, fractional anisotropy (FA), axial diffusivity (AD), and radial diffusivity (RD) were calculated, with the first two scans matched in time to blood assays. Linear regression models investigated interactions of each inflammatory marker change score (separately) and either discrimination or early life adversity (separately) on trace, FA, AD, and RD slopes as individual outcomes adjusting for age, sex, education, white matter hyperintensities (total volume and voxelwise), cardiovascular risk factors, statin and analgesic medications, thyroid conditions, and depression. Statistical significance was determined at p&lt;0.05 using family wise error correction and threshold free cluster enhancement.Results:Discrimination moderated the relationship between TNF-a and AD whereby those with increasing TNF-a and higher levels of discrimination had increasing levels of AD over time in white matter tracts connecting the left and right cerebellum, the left pallidum and medulla, and the left superior frontal gyrus and left thalamus. Both discrimination and early life adversity moderated associations between CRP and AD, where increases in CRP and higher psychosocial stressors (of either type) resulted in decreasing AD over time in tracts involving cingulate, frontal, and parietal regions. Discrimination and early life adversity also moderated associations between CRP and RD, where increasing CRP combined with greater psychosocial stressors resulted in decreasing RD in right hemisphere association and projection tracts connecting frontal, parietal, central, and subcortical regions.Conclusions:TNF-a and CRP interacted with measures of psychosocial stress to associate with DTI-derived TBSS slope change measures of AD and RD in differential, and at times, paradoxical ways. Findings suggest that both risk and resilience as related to brain connectivity may be co-occurring in the presence of psychosocial stressors for older Black adults.

Association of Olfaction and Microstructural Integrity of Brain Tissue in Community-Dwelling Adults: Atherosclerosis Risk in Communities Neurocognitive Study.

Research on olfaction and brain neuropathology may help understand brain regions associated with normal olfaction and dementia pathophysiology. To identify early regional brain structures affected in poor olfaction, we examined cross-sectional associations of microstructural integrity of the brain with olfaction in the Atherosclerosis Risk in Communities Neurocognitive Study. Participants were selected from a prospective cohort study of community-dwelling adults; selection criteria included: evidence of cognitive impairment, participation in a previous MRI study, and a random sample of cognitively normal participants. Microstructural integrity was measured by two diffusion tensor imaging (DTI) measures, fractional anisotropy (FA) and mean diffusivity (MD), and olfaction by a 12-item odor-identification test at the same visit. Higher FA and MD values indicate better and worse microstructural integrity, respectively, and higher odor-identification scores indicate better olfaction. We used brain region-specific linear regression models to examine associations between DTI measures and olfaction, adjusting for potential confounders. Among 1,418 participants (mean age: 76±5years, 41% male, 21% Black race, 59% with normal cognition), the mean olfaction score was 9±2.3. Relevant to olfaction, higher MD in the medial temporal lobe (MTL) regions, namely, the hippocampus (β: -0.79 (95%CI: -0.94, -0.65) units lower olfaction score per SD higher MD), amygdala, entorhinal area, and some white matter (WM) tracts connecting to these regions, was associated with olfaction. We also observed associations with MD and WM FA in multiple atlas regions that were not previously implicated in olfaction. The associations between MD and olfaction were particularly stronger in the MTL regions among individuals with mild cognitive impairment (MCI) compared to those with normal cognition (e.g., βhippocampus: -0.75 (95%CI: -1.02, -0.49) and -0.44 (95%CI: -0.63, -0.26) for MCI and normal cognition, respectively, p-interaction=0.004). Neuronal microstructural integrity in multiple brain regions, in particular the MTL (the regions known to be affected in early Alzheimer's), is associated with odor-identification ability. Differential associations in the MTL regions among cognitively normal individuals compared to those with MCI may reflect the earlier vs. later effects of the dementia pathogenesis. It is likely that some of the associated regions may not have any functional relevance to olfaction.

Development and benchmarking diffusion magnetic resonance imaging analysis for integration into radiation treatment planning.

The rising promise in the utility of advanced multi-parametric magnetic resonance (MR) imaging in radiotherapy (RT) treatment planning creates a necessity for testing and enhancing the accuracy of quantitative imaging analysis. Standardizing the analysis of diffusion weighted imaging (DWI) and diffusion tensor imaging (DTI) to generate meaningful and reproducible apparent diffusion coefficient (ADC) and fractional anisotropy (FA) lays the requisite needed for clinical integration. The aim of the demonstrated work is to benchmark the generation of the ADC and FA parametric map analyses using integrated tools in a commercial treatment planning system against the currently used ones. Three software packages were used for generating ADC and FA maps in this study; one tool was developed within a commercial treatment planning system, another by the Functional Magnetic Resonance Imaging of the Brain (FMRIB) Software Library FSL (Analysis Group, FMRIB, Oxford, United Kingdom), and an in-house tool developed at the M.D. Anderson Cancer Center. The ADC and FA maps generated by all three packages for 35 subjects were subtracted from one another, and the standard deviation of the images' differences was used to compare the reproducibility. The reproducibility of the ADC maps was compared with the Quantitative Imaging Biomarkers Alliance (QIBA) protocol, while that of the FA maps was compared to data in published literature. Results show that the discrepancies between the ADC maps calculated for each patient using the three different software algorithms are less than 2% which meets the 3.6% recommended QIBA requirement. Except for a small number of isolated points, the majority of differences in FA maps for each patient produced by the three methods did not exceed 0.02 which is 10 times lower than the differences seen in healthy gray and white matter. The results were also compared to the maps generated by existing MR Imaging consoles and showed that the robustness of console generated ADC and FA maps is largely dependent on the correct application of scaling factors, that only if correctly placed; the differences between the three tested methods and the console generated values were within the recommended QIBA guidelines. Cross-comparison difference maps demonstrated that quantitative reproducibility of ADC and FA metrics generated using our tested commercial treatment planning system were comparable to in-house and established tools as benchmarks. This integrated approach facilitates the clinical utility of diffusion imaging in radiation treatment planning workflow.

Magnetic Resonance Diffusion Tensor Imaging Characterize the Hepatic Ischemia-Reperfusion Injury in an Animal Study

Hepatic ischemia-reperfusion (I/R) injury is the main cause of morbidity and mortality after hepatectomy; thus, new methods for reducing I/R injury are required. The aim of this study is to evaluate changes in the average apparent diffusion coefficient (ADCavg) and fractional anisotropy (FA) in rabbits with partial hepatic I/R injury with magnetic resonance diffusion tensor imaging (DTI). The left lobe of the rabbit liver underwent 60 minutes of ischemia followed by 0.5, 2, 6, 12, 24, and 48 hours of reperfusion. T2-weighted images (T2WI), T1-weighted images (T1WI), DTI, and contrast-enhanced T1WI were performed; 6 b values were used for DTI on 6 diffusion directions. The serum levels of transaminases and liver histopathology findings were examined. In the early stage of I/R (0.5 hour), ADCavg decreased significantly and increased sharply to 2 hours, then increased from 6 hours to 48 hours of reperfusion, except for a transient decrease (24 hours). Meanwhile, FA showed almost the opposite trend, drastically increasing during the first 0.5 hour and then slightly decreasing until 48 hours of reperfusion, except for an obvious decrease in the 2-hours group. The serum levels of liver markers and the pathologic scores were sharply increased in the I/R group after reperfusion and correlated with DTI of hepatic tissue after I/R. Diffusion tensor imaging is feasible for imaging I/R-induced liver damage and can discriminate isotropic properties of the liver after I/R injury with objective changes in the ADCavg and FA. Diffusion tensor imaging can be a promising novel approach for use in clinical management after liver surgery.

Nigral Pathology Contributes to Microstructural Integrity of Striatal and Frontal Tracts in Parkinson's Disease.

Motor and cognitive impairment in Parkinson's disease (PD) is associated with dopaminergic dysfunction that stems from substantia nigra (SN) degeneration and concomitant α-synuclein accumulation. Diffusion magnetic resonance imaging (MRI) can detect microstructural alterations of the SN and its tracts to (sub)cortical regions, but their pathological sensitivity is still poorly understood. To unravel the pathological substrate(s) underlying microstructural alterations of SN, and its tracts to the dorsal striatum and dorsolateral prefrontal cortex (DLPFC) in PD. Combining post-mortem in situ MRI and histopathology, T1-weighted and diffusion MRI, and neuropathological samples of nine PD, six PD with dementia (PDD), five dementia with Lewy bodies (DLB), and 10 control donors were collected. From diffusion MRI, mean diffusivity (MD) and fractional anisotropy (FA) were derived from the SN, and tracts between the SN and caudate nucleus, putamen, and DLPFC. Phosphorylated-Ser129-α-synuclein and tyrosine hydroxylase immunohistochemistry was included to quantify nigral Lewy pathology and dopaminergic degeneration, respectively. Compared to controls, PD and PDD/DLB showed increased MD of the SN and SN-DLPFC tract, as well as increased FA of the SN-caudate nucleus tract. Both PD and PDD/DLB showed nigral Lewy pathology and dopaminergic loss compared to controls. Increased MD of the SN and FA of SN-caudate nucleus tract were associated with SN dopaminergic loss. Whereas increased MD of the SN-DLPFC tract was associated with increased SN Lewy neurite load. In PD and PDD/DLB, diffusion MRI captures microstructural alterations of the SN and tracts to the dorsal striatum and DLPFC, which differentially associates with SN dopaminergic degeneration and Lewy neurite pathology. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Improved prediction of glioma-related aphasia by diffusion MRI metrics, machine learning, and automated fiber bundle segmentation.

White matter impairments caused by gliomas can lead to functional disorders. In this study, we predicted aphasia in patients with gliomas infiltrating the language network using machine learning methods. We included 78 patients with left-hemispheric perisylvian gliomas. Aphasia was graded preoperatively using the Aachen aphasia test (AAT). Subsequently, we created bundle segmentations based on automatically generated tract orientation mappings using TractSeg. To prepare the input for the support vector machine (SVM), we first preselected aphasia-related fiber bundles based on the associations between relative tract volumes and AAT subtests. In addition, diffusion magnetic resonance imaging (dMRI)-based metrics [axial diffusivity (AD), apparent diffusion coefficient (ADC), fractional anisotropy (FA), and radial diffusivity (RD)] were extracted within the fiber bundles' masks with their mean, standard deviation, kurtosis, and skewness values. Our model consisted of random forest-based feature selection followed by an SVM. The best model performance achieved 81% accuracy (specificity = 85%, sensitivity = 73%, and AUC = 85%) using dMRI-based features, demographics, tumor WHO grade, tumor location, and relative tract volumes. The most effective features resulted from the arcuate fasciculus (AF), middle longitudinal fasciculus (MLF), and inferior fronto-occipital fasciculus (IFOF). The most effective dMRI-based metrics were FA, ADC, and AD. We achieved a prediction of aphasia using dMRI-based features and demonstrated that AF, IFOF, and MLF were the most important fiber bundles for predicting aphasia in this cohort.

A Prospective Study to Evaluate the Clinical and Diffusion Tensor Imaging (DTI) Correlation in Patients with Lumbar Disc Herniation with Radiculopathy.

Conventional magnetic resonance imaging findings frequently do not correlate with the symptoms of lumbar disc herniation (LDH). Diffusion-weighted imaging can reveal important details about the microstructure of tissues. This study assessed the role of diffusion-weighted imaging (DTI) in LDH with radiculopathy and explored the relationship between DTI values and clinical scores. Forty-five patients with LDH with radiculopathy were evaluated via DTI at the intraspinal (IS), intraforaminal (IF), and extraforaminal (EF) levels. A visual analog scale (VAS) was used for low back and leg pain. The Japanese Orthopaedic Association (JOA) scoring system, Oswestry Disability Index (ODI), and Roland-Morris Disability Questionnaire (RMDQ) were used for functional evaluation. There was a statistically significantly (p<0.05) difference between the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values on the affected side compared with those on contralateral normal side. The VAS score had a weak positive correlation with RMDQ score (r=0.279, P=0.050). The JOA score had a moderate negative correlation with RMDQ score (r=-0.428, P=0.002), whereas the ODI score had a moderate positive correlation with RMDQ score (r=0.554, P<0.001). There was a moderate positive correlation between ADC values at the IF level and the RMDQ score on the affected side (r=0.310, P=0.029). There was no correlation between FA values and JOA score. ODI had a significantly positive correlation with the contralateral normal side FA values at the IF (r=0.399, P=0.015), EF (r=0.368, P=0.008) and IS (r=0.343, P=0.015) levels. RMDQ had a weak positive correlation with the contralateral normal side FA values at the IF (r=0.311, P=0.028), IS (r=0.297, P=0.036) and EF (r=0.297, P=0.036) levels. The decrease in FA values and the increase in ADC values are useful markers of compression. ADC correlates well with the patient's neurological symptoms and functional status. Conversely, FA correlates well with the patient's neurological symptoms, but is not correlated well with the functional status.

The additive value of diffusion tensor imaging in the determination of perianal fistula activity

BackgroundAlthough the activity of the perianal fistula has been evaluated before by MRI in the literature, limited diffusion tensor magnetic resonance imaging (DT-MRI) studies are reported to date. Our study aimed to elucidate the role of DT-MRI in evaluating the activity state of the perianal fistula and the prediction of postoperative complications. We reviewed the data of 30 patients diagnosed with perianal fistula and referred them for an MRI diffusion study before the surgical intervention. Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) were calculated for the fistulous area and the normal surrounding puborectalis as a control area.ResultsAccording to the presence of pus intraoperatively, patients were allocated into two groups: the active group (10 patients) and the inactive group (20 patients). FA and ADC measurements showed a significant decrease in association with the active disease when measured at the fistula site, and this was not observed in the normal surrounding tissues. The area under the curve (AUC) was 0.985 and 0.730 for the ADC and FA, respectively, when cutoff values of 1 × 10–3 mm2/s and 0.621 were applied, respectively. Adding the FA to the ADC increased the DT-MRI specificity to 95% in the determination of the active fistula. The combination between both FA and ADC increased the AUC to 0.785 with a sensitivity of 73.7% and specificity of 63.6% in the detection of postoperative complications.ConclusionsDT-MRI could be used as a reliable diagnostic tool to differentiate patients with active perianal fistula disease from inactive ones and to predict the postoperative outcome.

A Diagnostic Biomarker for Cervical Myelopathy Based on Dynamic Magnetic Resonance Imaging.

Multicenter prospective observational study. Diffusion tensor imaging in flexion extension improves the diagnosis of degenerative cervical myelopathy (DCM). We aimed to provide an imaging biomarker for the detection of DCM. DCM is the most common form of spinal cord dysfunction in adults; however, imaging surveillance for myelopathy remains poorly characterized. Symptomatic DCM patients were examined in maximum neck flexion-extension and neutral positions in a 3T-magnetic resonance imaging scanner and allocated to 2 groups: (1) Patients with visible intramedullary hyperintensity (IHIS) on T2-weighted imaging (IHIS+, n = 10); and (2) Patients without IHIS (IHIS-, n = 11). Range of motion, space available for the spinal cord, apparent diffusion coefficient (ADC), axial diffusivity (AD), radial diffusivity, and fractional anisotropy were measured and compared between the neck positions and between the groups as well as between control (C2/3) and pathologic segments. Significant differences between the control level (C2/3) and pathologic segments were appreciated for the IHIS+ group at neutral neck position in AD; at flexion in ADC and AD; and at neck extension in ADC, AD, and fractional anisotropy values. For the IHIS- group, significant differences between the control level (C2/3) and pathologic segments were found only for ADC values in neck extension. When comparing diffusion parameters between groups, radial diffusivity was significantly different in all 3 neck positions. Significant increases in ADC values between the control and pathologic segments were found for both groups in neck extension only. This may serve as a diagnostic tool to identify early changes in the spinal cord related to myelopathy to indicate potentially reversible spinal cord injury and support the indication for surgery in select circumstances.

Characterization of motion dependent magnetic field inhomogeneity for DWI in the kidneys

PurposeDiffusion-weighted imaging (DWI) of the abdomen has increased dramatically for both research and clinical purposes. Motion and static field inhomogeneity related challenges limit image quality of abdominopelvic imaging with the most conventional echo-planar imaging (EPI) pulse sequence. While reversed phase encoded imaging is increasingly used to facilitate distortion correction, it typically assumes one motion independent magnetic field distribution. In this study, we describe a more generalized workflow for the case of kidney DWI in which the field inhomogeneity at multiple respiratory phases is mapped and used to correct all images in a multi-contrast DWI series. MethodsIn this HIPAA-compliant and IRB-approved prospective study, 8 volunteers (6 M, ages 28–51) had abdominal imaging performed in a 3 T MRI system (MAGNETOM Prisma; Siemens Healthcare, Erlangen, Germany) with ECG gating. Coronal oblique T2-weighted HASTE images were collected for anatomical reference. Sagittal phase-contrast (PC) MRI images through the left renal artery were collected to determine systolic and diastolic phases. Cardiac triggered oblique coronal DWI were collected at 10 b-values between 0 and 800 s/mm2 and 12 directions. DWI series were distortion corrected using field maps generated by forward and reversed phase encoded b = 0 images collected over the full respiratory cycle and matched by respiratory phase. Morphologic accuracy, intraseries spatial variability, and diffusion tensor imaging (DTI) metrics mean diffusivity (MD) and fractional anisotropy (FA) were compared for results generated with no distortion correction, correction with only one respiratory bin, and correction with multiple respiratory bins across the breathing cycle. ResultsComputed field maps showed significant variation in static field with kidney laterality, region, and respiratory phase. Distortion corrected images showed significantly better registration to morphologic images than uncorrected images; for the left kidney, the multiple bin correction outperformed one bin correction. Line profile analysis showed significantly reduced spatial variation with multiple bins than one bin correction. DTI metrics were mostly similar between correction methods, with some differences observed in MD between uncorrected and corrected datasets. ConclusionsOur results indicate improved morphology of kidney DWI and derived parametric maps as well as reduced variability over the full image series using the motion-resolved distortion correction. This work highlights some morphologic and quantitative metric improvements can be obtained for kidney DWI when distortion correction is performed in a respiratory-resolved manner.