Diffusion Tensor Imaging in Musculoskeletal Disorders

Introduction We present the first study in literature that documents the changes in diffusion tensor imaging (DTI) indices and tractography after surgical decompression in patients with cervical myelopathy. DTI, an established tool for tracking nerve fibers in brain, is now widely evaluated for its usefulness in spine pathologies. Although there are many studies directly comparing DTI indices of control and cervical myelopathic patients, there are no studies that have evaluated the prognostic applicability of DTI indices. The present study analyzes the pre- and postdecompression DTI indices and tractography in cervical myelopathic patients and its prognostic value. Materials and Methods Total 56 subjects including 16 cervical myelopathy patients who required surgical decompression (mean age: 53.5 ± 12.3 years, males: 15, females: (1) and forty normal controls (mean age: 38.18 ± 13.74 years, males: 20, females: 20) were included in the study. DTI of cervical spine was obtained using an axial single shot echo-planar parallel diffusion-weighted imaging sequence in a 1.5 tesla magnetic resonance imaging (MRI). Apparent diffusion coefficient (ADC), fractional anisotropy (FA), and Eigen values (E1, E2, and E3) were obtained at each region of interest (cervical disk level) from C1-C2 to C7-T1. The DTI indices of myelopathic patients were compared with normal volunteers after matching was done based on sex, cord level, and cord size. Postoperatively, the patients were followed up after 6 months and DTI scan was performed again. The clinical improvement and the DTI indices observed at the follow-up were compared with the preoperative values. Results Analysis showed significant differences between the controls and patients in all the indices (p<0.05) at the site of compression. At the compressed levels, FA decreased while all the other indices increased as compared to the controls. The mean DTI indices of myelopathic patients before surgery at the sites of spinal cord compression were as follows: FA (0.49 ± 0.092), ADC (1.8 ± 0.32 µm2/ms), E1 (2.80 ± 0.44 µm2/ms), E2 (1.63 ± 0.45 µm2/ms), E3 (0.95 ± 0.23 µm2/ms). The average DTI indices of matched controls were as follows: FA (0.55 ± 0.033), ADC (1.47 ± 0.066 µm2/ms), E1 (2.49 ± 0.150 µm2/ms), E2 (1.16 ± 0.050 µm2/ms), E3 (0.77 ± 0.058 µm2/ms. The Nurick grading distribution in patients before surgery was as follows: Grade 2 = 2, Gr 3 = 8, Gr 4 = 2, Gr 5 = 4. Postoperatively, all the patients had improvement of neurology by at least one Nurick grade except for one patient who had no improvement. The Nurick grading distribution in patients during 6 months follow-up after surgery was as follows: Grade 0 = 3, Gr 1 = 6, Gr 2 = 2, Gr 3 = 3, Gr 4 = 2. Mean postoperative values of ADC, E1, and E2 showed improvement towards normal values especially in patients with preoperative Nurick grade 2 and 3 (Table 1). Patients with Nurick grade 4 and 5 did not show any significant change. The mean FA and E3 values worsened when compared to preoperative DTI indices. The postoperative DTI indices for the patients who had neurological improvement are as follows: FA (0.45 ± 0.087), ADC (1.73 ± 0.31 µm2/ms), E1 (2.59 ± 0.28 µm2/ms), E2 (1.56 ± 0.38 µm2/ms), E3 (1.07 ± 0.31 µm2/ms. Tractography also showed interruption of nerve fibre tract continuity at the level of severe compression in patients with myelopathy. At levels of moderate compression over the spinal cord, the changes in direction of nerve fibres due to bulging disc-osteophytes were evident as changes in color coding of the tracts. After surgical decompression, the restitution of fibre tract pathways was clearly demonstrated in DT tractography. Conclusion For the first time, the prognostic applicability of DTI by comparing pre- and postoperative indices of cervical myelopathy patients has been described. All preoperative DTI indices at compressed levels showed significant differences from controls indicating abnormality in neuronal integrity. All but one of the patients showed clinical improvement at 6 months. The postoperative DTI values (ADC, E1 and E2) of patients with Nurick grading 2 and 3 were observed to approach normal values indicating restoration of linear diffusion in neuronal tracts. DTI indices in patients with Nurick grade 4 and 5 remained same or worsened more. This could probably indicate persistent axonal damage. At 6 months postsurgery, DTI indices show evidence of improvement towards normal values, even though the values did not match the true extent of clinical improvement. Further DTI evaluation at 12 months and 2 years is required to analyze the extent of usefulness of DTI indices in evaluating cervical myelopathy. The results suggest that DTI indices, especially ADC and Eigen vectors can be promising indicators in the evaluation and prognostic assessment of myelopathy patients. I confirm having declared any potential conflict of interest for all authors listed on this abstract Yes Disclosure of Interest None declared

Objective To investigate the value of diffusion tensor imaging (DTI) at high b value for unilateral middle cerebral artery (MCA) occlusive disease in patients without obvious infarct lesions on conventional MR imaging.Methods DTI at high b value (2200 s/mm2 ) was performed using a 3.0 Tesla MR scanner in 34 patients with unilateral middle cerebral artery occlusion,who had no obvious infarct lesions on conventional MR imaging. Fractional anisotropy (FA),apparent diffusion coefficient (ADC),axial diffusivity (eigenvalue λ1) and radial diffusivity (eigenvalues λ2,λ3) were measured at the ipsilateral and contralateral corona radiata,anterior and posterior limbs of the internal capsule,cerebral peduncle and pons in all subjects.Mean ADC,FA,λ1,λ2 and λ3 values of corona radiata,anterior and posterior limbs of the internal capsule,cerebral peduncle and pons were compared between the ipsilateral and contralateral MCA territory by t test. Results Among the 34 patients,left MCA occlusion in M1 segment occurred in 16 patients and right MCA occlusion in Ml segment occurred in 18 patients.At the ipsilateral corona radiata,mean FA,ADC,λ1,λ2 and λ3 were 0.419 ±0.032,(5.975 ±0.272) × 10 3,(5.704 ±0.365) ×10-3,(6.412 ±0.368) × 10-3 and (6.605 ±0.343) × 10-3 mm2/s,respectively.At the contralateral corona radiata,mean FA,ADC,λ1,λ2 and λ3 were 0.443 ± 0.033,(5.804 ± 0.282) × 10 -3,(5.651 ±0.350) × 10-3,(6.099 ±0.353) × 10-3 and(6.372 ±0.355) × 10-3 mm2/s,respectively.At the ipsilateral corona radiata,mean FA was significantly decreased(t =11.614,P ＜0.01),and mean ADC (t=12.421,P＜0.01),λ1(t =7.447,P＜0.01),λ2(t=10.244,P＜0.01) and λ3(t=9.890,P＜0.01) were significantly increased.At the ipsilateral anterior and posterior limb of the internal capsule,mean FA were 0.609 ±0.026 and 0.674 ±0.033,λ1 were(5.330 ±0.462) × 10 -3 and(5.171 ±0.456) ×10-3 mm2/s,respectively.At the contralateral anterior and posterior limb of the internal capsule,FA were 0.622 ±0.026 and 0.694 ±0.034,λ1 were(5.064 ± 0.448) × 10 -3 and(4.924 ± 0.365) × 10 -3 mm2/s,respectively.Mean FA was significantly decreased (t =7.823,8.013,all P ＜ 0.01) and mean λ1 was significantly increased (t =7.811,8.800,all P ＜0.01) at the ipsilateral anterior and posterior limbs of the internal capsule.There was no significant difference in ADC,λ2 and λ3 value between the ipsilateral and contralateral sides.And all the DTI parameters,including mean ADC,FA,λ1,λ2 and λ3 values,showed no statistical difference between both sides of cerebral peduncle and pons.Conclusion DTI at high b valuc can provide useful information for visualizing ischemic white matter injury in patients without obvious infarct lesions on conventional MR imaging. Key words: Infarction, middle cerebral artery; Diffusion magnetic resonance imaging

Introduction: The conventional magnetic resonance imaging (MRI) method is widely considered ‘with limited success’ in differentiating the meningioma types but may fail to localize the tumor occupation of white-matter fiber bundles accurately. Diffusion tensor imaging (DTI) is considered as an imaging modality that may elucidate the microstructure of brain tumors. We provide characteristics of meningioma using DTI-based-three-dimensional tracing of white matter to portray meningioma in a noninvasive approach and its structural contact to contiguous tumors and elucidate the influence of occupying lesions on white-matter fiber bundles. Case Presentation: A 28-year-old female presented with visuospatial disturbances and persistent headaches for 2 years. Conventional and advanced MRI studies were performed. Diffusion-weighted Images (DWI) and Apparent Diffusion Coefficient (ADC) values were measured in the lesion using routine MRI sequences. Advanced MRI using DTI was also performed. Conventional MRI outcomes showed tumor parenchyma, peritumoral edema, and compression on the circumnavigated brain tissue. There was hyperintense on DW trace image and isointense on ADC map. On T2-weighted image (T2WI) and Fluid-Attenuated Inversion Recovery (FLAIR) images, there was an increased signal intensity that demonstrated an extra-axial lesion, while T1-weighted imaging signals showed hypointensity. DTI fractional anisotropy (FA) marker is an unclear optic radiation in the concerned area, indicating the shift or destruction of the optic radiation. The mean FA values of solid-enhancing areas of meningioma were 0.28 ± 0.17. Mean ADC values (103 mm2/s) were 0.764 ± 0.172. Conclusions: Classic meningioma in this case has low intratumoral FA and high ADC. DTI displayed that intratumoral microscopic water motion is disorganized.

This thesis aimed to investigate the feasibility of two diffusion imaging techniques, Diffusion Tensor Imaging (DTI) and Diffusion Kurtosis Imaging (DKI), on detecting subtle physiological or pathological microstructural changes in normal-appearing neural tissues of human central nervous system. 
\n At first, ten patients with neuromyelitis optica (NMO) and twelve age- and gender-matched healthy subjects were recruited. DTI-derived indices including fractional anisotropy (FA), mean diffusivity (MD), axial and radial diffusivities were quantified in the lateral and dorsal columns of cervical spinal cord. Based on the regions of interest (ROIs) measurement, NMO patients showed reduced FA, increased MD and radial diffusivity compared to control subjects, while axial diffusivity did not show any significant difference. The three former DTI metrics also showed significant correlations with disability scores, and especially FA was found to be sensitive to mild NMO. Our results show that DTI-derived indices can quantitatively assess the white matter (WM) abnormalities with seemingly normal appearance in conventional MRI, and are associated with the level of clinical disability, suggesting that DTI may have great potential as a useful diagnostic tool in the clinical setting.
\n DKI is an extension of conventional DTI to probe the non-Gaussian diffusion property in biological tissues. Besides the four conventional DTI-derived metrics, DKI also provide three additional kurtosis metrics (mean kurtosis (MK), axial and radial kurtosis). In the second study, ROI-based analysis was used to characterize age-related microstructural changes in WM, cortical and subcortical gray matter (GM) of 27 healthy adults (21~59 yrs). Though the volumes of GM and WM were still preserved, DTI-derived metrics can detect the subtle changes in WM and GM. Meanwhile, MK and radial kurtosis significantly increased in both caudate nucleus and putamen while Thalamus showed little aging effect in the diffusivity and kurtosis metrics but significantly decreased only in FA. Our results demonstrated that DKI is sensitive to detect the age-related alterations in neural microstructures at the stage of early aging.
\n In addition, DKI has been applied to detect the pathological changes in the normal-appearing neural tissues of 18 patients with multiple sclerosis (MS), compared to 22 healthy controls. Diffuse WM abnormalities have been observed extensively in the brain, revealed by DKI-derived metrics. Though the volumetric and voxel-wise analysis revealed no significant changes in the volume of cortical GM, decreased FA and kurtoses with increased diffusivities in MS group were sensitive to disclose the subtle alterations in global and regional cortical GM tissues. Significant correlations have been found between FA in the global, frontal and temporal cortical GM in relapsing-remitting MS patients and their disability scores, suggesting FA as an important biomarker to monitor the disease progress in cortical GM. Moreover, elevated kurtosis indices in MS patients did not correlate with diffusivities in caudate nucleus, putamen and thalamus, suggesting these metrics may be vulnerable to different pathologic aspects of the disease.
\n In conclusion, DKI is sensitive to neural alterations during normal aging and in MS pathologies, and can provide complementary information to conventional MRI and DTI.

To apply diffusion tensor imaging (DTI) and tractography to the median nerve by use of a 3-T MRI device in order to demonstrate potential differences in diffusion parameters between healthy subjects and patients with carpal tunnel syndrome (CTS). The median nerve of 15 patients and 20 healthy volunteers was examined in two sequences: DTI and a high-resolution T1-weighted sequence. Mean fractional anisotropy (FA) and mean apparent diffusion coefficient (ADC) were measured based on tractography findings. Mean FA was significantly lower in CTS patients (P = 0.01) whereas no significant difference was found in mean ADC. Focal measurements of FA and ADC were also obtained at three locations along the course of the median nerve. We observed a highly significant difference (P < 0.0001) between FA measured at the proximal carpus and FA measured at the distal carpus in healthy subjects and CTS patients. Focal FA values along the median nerve showed an opposite trend in the two groups: in healthy subjects FA tended to increase (P < 0.05) whereas in subjects with CTS it tended to decrease (P = 0.0001). We defined a threshold value of -0.058 (FA3-FA1) that was sensitive and specific for nerve compression. DTI and tractography can detect chronic nerve compression. • Diffusion tensor magnetic resonance imaging offers new information about carpal tunnel syndrome. • Diffusion tensor MRI of the median nerve provides some functional data. • Mean fractional anisotropy (FA) was lower in patients with CTS than volunteers. • There was no significant difference in ADC values between patients and volunteers. • Fractional anisotropy seems a sensitive and specific predictor of chronic nerve compression.

Background: Carpal Tunnel Syndrome (CTS) is the most common peripheral neuropathy of an upper extremity. The diagnosis of CTS is commonly based on findings from the medical history, physical examination, and provocative tests. To confirm the diagnosis, some clinician accepts Electrophys-iological Studies (EPS) as the reference standard. Diffusion-Tensor Imaging (DTI) is a subtype of diffusion-weighted imaging based on measurement of molecular diffusion along multiple directions in space. Directional anisotropy of water diffusibility can be quantified by imaging indices such as Apparent Diffusion Coefficient (ADC) and Fractional Anisot-ropy (FA) used to characterize the degree of diffusion anisot-ropy.Aim of Work: The aim of this study is to study the efficacy of diffusion tensor imaging in the diagnosis of carpal tunnel syndrome.Material and Methods: Twenty-three wrists of 15 healthy subjects and 47 wrists of 31 CTS patients were evaluated with DTI and EPS. FA and ADC of the median nerve were calculated at four locations: Distal radioulnar joint, pisiform bone, hamate bone and hamate hook, and also determined from the whole median nerve. Electrophysiological test, including nerve conduction velocity was also performed for comparison with clinical assessment as a standard of reference.Results: There was a significant difference between healthy individuals and patients with carpal tunnel syndrome (p<0.01 for both FA and ADC). FA value less than 0.54 and ADC value more than 1.19 X 1 0–3mm2/sec might be used in the diagnosis of carpal tunnel syndrome. As regards the DTI results, the sensitivity, specificity, negative predictive value, positive predictive value and accuracy were 97.8%, 95.6%, 95.6%, 97.8% and 97.1% respectively.Conclusion: DTI scan contribute to carpal tunnel syndrome diagnosis on the basis of FA and ADC measurements.

The aim of this study was to describe the development of morphologic and diffusion tensor imaging sequences of peripheral nerves at 7 T, using carpal tunnel syndrome (CTS) as a model system of focal nerve injury. Morphologic images were acquired at 7 T using a balanced steady-state free precession sequence. Diffusion tensor imaging was performed using single-shot echo-planar imaging and readout-segmented echo-planar imaging sequences. Different acquisition and postprocessing methods were compared to describe the optimal analysis pipeline. Magnetic resonance imaging parameters including cross-sectional areas, signal intensity, fractional anisotropy (FA), as well as mean, axial, and radial diffusivity were compared between patients with CTS (n = 8) and healthy controls (n = 6) using analyses of covariance corrected for age (significance set at P < 0.05). Pearson correlations with Bonferroni correction were used to determine association of magnetic resonance imaging parameters with clinical measures (significance set at P < 0.01). The 7 T acquisitions with high in-plane resolution (0.2 × 0.2mm) afforded detailed morphologic resolution of peripheral nerve fascicles. For diffusion tensor imaging, single-shot echo-planar imaging was more efficient than readout-segmented echo-planar imaging in terms of signal-to-noise ratio per unit scan time. Distortion artifacts were pronounced, but could be corrected during postprocessing. Registration of FA maps to the morphologic images was successful. The developed imaging and analysis pipeline identified lower median nerve FA (pisiform bone, 0.37 [SD 0.10]) and higher radial diffusivity (1.08 [0.20]) in patients with CTS compared with healthy controls (0.53 [0.06] and 0.78 [0.11], respectively, P < 0.047). Fractional anisotropy and radial diffusivity strongly correlated with patients' symptoms (r = -0.866 and 0.866, respectively, P = 0.005). Our data demonstrate the feasibility of morphologic and diffusion peripheral nerve imaging at 7 T. Fractional anisotropy and radial diffusivity were found to be correlates of symptom severity.

Objective To analyze the characteristics of magnetic resonance diffusion tensor imaging(DTI)and diffusion tensor tractography (DTIT) in patients with cerebral infarction, and explore the diagnosis values and prognosis of diffusion weighted imaging (DWI) and diffusion tensor imaging (DTI) in patients with cerebral infarction in different stages. Methods 58 patients with cerebral infarction in different stages and 25 healthy volunteers were examined by magnetic resonance imaging (MRI), including conventional T1 and T2 weighted imaging, DWI and DTI. Fractional anisotropy (FA) images were reconstructed. The values of FA and apparent diffusion coefficient (ADC) were measured in the infarcted regions, corresponding contralateral normal regions and corresponding normal regions in normal control group. Results ①DWI and DTI showed size of infarction focus was more accurate and clearer than that of conventional MRI; ②The FA and ADC values of the infarcted regions during superacute stage, acute stage, subacute stage and chronic stage were (0.24±0.02, 0.31 ±0.11), (0.20±0.02, 0.32±0.12), (0.18±0.02, 0.34±0.11) and (0.16±0.02, 0.37±0.13), respectively, lower than those in the contralateral corresponding regions which were (0.40±0.03, 0.70±0.21), (0.37±0.03, 0.71±0.21), (0.39±0.03, 0.72±0.22) and (0.40:±0.03, 0.72±0.23), respectively. The differences were statistically significant (P＜0.05). The FA and ADC values had no significant differences between the uninjured sides in patients with cerebral infarction and the corresponding regions in the normal control group (P＞0.05); ③The FA and ADC values in brain tissues changed regularly with the time of infarction after cerebral infarction. The FA values in the affected sides had no consistent changes as compared with the contralateral sides in the superacute stage. They increased or decreased slightly, then (during acute stage, subacute stage and chronic stage) decreased irreversibly. The ADC values in the affected sides changed with time regularly, they decreased significantly, gradually returned to normal, and then increased again. Conclusion DTI and DTT examination contribute to the diagnosis of cerebral infarction. The combination of the FA and ADC values may more accurately conduct clinical staging and evaluate the time of the occurrence of cerebral infarction. Key words: Magnetic resonance; Cerebral infarction; Diffusion tensor imaging; Diffusion tensor tractography

Background: Carpal tunnel syndrome (CTS) is a common peripheral nerve entrapment disorder that is diagnosed using clinical signs and symptoms and confirmed via nerve conduction studies (NCSs). While NCS is a semi-invasive procedure, magnetic resonance imaging (MRI) is a non-invasive diagnostic tool that detects macroscopic nerve abnormalities and evaluates a patient's surgical or medication treatment options. This study assessed magnetic resonance neurography (MRN)'s diagnostic and grading value by comparing it to electrodiagnostic studies in patients with CTS and healthy individuals. Methods: This was a cross-sectional study on 27 wrists with CTS and 27 healthy wrists. After history taking and physical examination, we employed an NCS to confirm and determine the severity of CTS, then MRN and diffusion tensor imaging (DTI) were used to calculate apparent diffusion coefficient (ADC), fractional anisotropy (FA), and cross-sectional area (CSA). Results: 18 patients with CTS (27 median nerves) and 15 healthy controls (27 median nerves) were evaluated. The mean FA in the CTS group was significantly lower (0.38 ± 0.05 vs. 0.45 ± 0.06, P < 0.001). The mean CSA and ADC were higher in patients with CTS but not statistically significant. FA's diagnostic cut-off was 0.42, with a sensitivity of 70.4% and a specificity of 63%. Conclusion: MRN with DTI can be an effective and non-invasive diagnostic technique for the detection of CTS. The FA measure demonstrated adequate sensitivity and specificity for differentiating patients with CTS from healthy individuals.

Tumors display chaotic vasculature that leads to hypoxia. Hypoxia is associated with an aggressive phenotype and increased resistance to radiation and chemotherapy. Hypoxic tumor regions also contain very few collagen 1 fibers, which is a major component of the tumor extracellular matrix (ECM) and plays an important role in molecular movement through the ECM. Here we examined the effects of hypoxia on water diffusion in a breast cancer xenograft model engineered to fluoresce under hypoxia. We observed, for the first time, that in hypoxic regions water diffusion and diffusion anisotropy was lower than in normoxic regions that may be explained by the few collagen fibers in hypoxic regions. Severe combined immunodeficient female mice were inoculated in the mammary fat pad with 2x106 MDA-MB-231 cells stably expressing red fluorescent protein (RFP) under the control of a hypoxia response element. Once tumor volume was approximately 300-400 mm3 the tumor was excised, fixed and imaged using high-resolution diffusion tensor imaging (DTI). The apparent diffusion coefficient (ADC) and fractional anisotropy (FA) maps were calculated. Following DTI, the tumor was sliced at 1 mm thick sections for optical imaging. Using a 1x lens to cover the entire tumor section, bright field and fluorescence optical images were acquired to detect the RFP-containing hypoxic regions. Multimodality registration was performed by feature extraction to co-register the optical images to the DTI images. Statistical dice similarity indices were calculated as a measure of the registration error. Hypoxic regions were identified from the optical fluorescence field images and the ADC and FA values were calculated in the corresponding hypoxic and normoxic regions. ADC and FA value distributions were identified in the DTI data and red fluorescent hypoxic regions were identified from the optical images. Co-registration accuracy confirmed by dice similarity index of 0.88 indicates a good overlap of optical and DTI images. Overall, hypoxic regions had lower water diffusion (ADC) and diffusion anisotropy (FA) values than normoxic regions. We have consistently observed that collagen fibers are significantly decreased in hypoxic regions, which could explain the lower ADC and FA values observed in hypoxic regions. In separate studies we have also observed high ADC in high collagen fiber containing regions in human breast cancer tissue. Low ADC and FA values observed in low collagen containing hypoxic regions indicate a functional role of these fibers in molecular transport. Decreased diffusion of molecules due to fewer collagen fibers in hypoxic regions may also contribute to poor drug delivery and tumor recurrence in hypoxic regions. Increased cellularity is thought to be one reason why lower ADC and FA values are observed in tumors. An even lower ADC within this backdrop may be due to hypoxic tumor regions. This work was supported by NIH P50CA103175 P30CA006973 Citation Format: Samata M. Kakkad, Jiangyang Zhang, Alireza Akhbardeh, Meiyappan Solaiyappan, Venu Raman, Dieter Leibfritz, Kristine Glunde, Zaver M. Bhujwalla. Water diffusion decreased in low collagen containing hypoxic regions of breast cancer xenograft. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 734. doi:10.1158/1538-7445.AM2013-734

Conventional advanced imaging for post-traumatic physeal bars of the distal tibia identifies abnormal ossification but provides limited information about the integrity of the remaining physis. This study sought to determine if diffusion tensor imaging (DTI) can noninvasively detect and quantify changes associated with the size of a post-traumatic physeal bar. We conducted a single-center, retrospective, cross-sectional study of 16 pediatric patients (mean age: 11.8±1.5y) with a radiographically confirmed unilateral post-traumatic physeal bar of the distal tibia. All patients underwent bilateral ankle MRI at 3.0 Tesla (T) with a DTI sequence. The contralateral healthy physis served as an internal control. Physeal bar size was quantified as a percentage of the total physeal cross-sectional area. Spearman correlation was used to assess the relationship between physeal bar size and DTI metrics, including fractional anisotropy (FA), apparent diffusion coefficient (ADC), and tractography-derived parameters. Physeal bar size demonstrated a strong positive correlation with FA within the region of interest (ρ=+0.71) and a strong negative correlation with ADC (ρ=-0.77) and radial diffusivity (ρ=-0.80). As bar size increased, tract count (ρ=-0.60) and tract volume (ρ=-0.65) on the affected side decreased significantly. Furthermore, physeal bar size strongly correlated with the magnitude of side-to-side asymmetry, particularly for the relative difference in tract volume (ρ=+0.76) and tract count (ρ=+0.74) between the injured and healthy ankles. This preliminary study demonstrates that DTI can detect and quantify significant alterations in the distal tibial physis that correlate with the size of the physeal bar noted on conventional imaging. The observed changes in tissue anisotropy and diffusion tract metrics suggest that DTI may serve as a sensitive imaging biomarker for assessing the true extent of the physeal injury. This technique holds promise for enhancing the early diagnosis and monitoring of pediatric growth disturbances. Level II.

Background:Diffusion tensor imaging (DTI) is a novel magnetic resonance imaging (MRI) technique potentially able to evaluate the microscopic structural organization of white matter fibers.Aim:This study aimed to compare fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values obtained by DTI in stenotic versus nonstenotic cervical spinal segments of patients with clinical and neurological evidence of cervical spondylotic myelopathy (CSM).Materials and Methods:This prospective study included 21 patients with CSM but without T2 changes on conventional MRI. Diffusion tensor (DT) images from the stenotic and nonstenotic segments of the subjects were obtained. FA and ADC values were estimated and compared with stenotic versus nonstenotic segments.Statistical Analysis:Paired t-test was used [Statistical Package for the Social Sciences (SPSS) 12.0].Results:In the most stenotic segments, the mean FA value was significantly lower (0.4228 ± 0.1090 vs 0.6884 ± 0.0075, P < 0.001) and the mean ADC value was significantly higher (1.312 ± 0.2405 vs 0.9183 ± 0.1477, P < 0.001) when compared to nonstenotic segments. In addition, there was a negative correlation between FA and ADC values (r = 0.63, P = 0.002).Conclusions:DTI of the cervical spine seems to be a promising novel imaging modality in patients with CSM.Advances in Knowledge:DTI may offer increased diagnostic sensitivity as compared to standard MRI and enables earlier detection of the disease.

Objective To estimate the value of diffusion tensor imaging (DTI) in early diagnosis of chronic allograft nephropathy (CAN) and monitoring of graft fibrosis in rat models. Methods Thirty CAN rat models were established as experimental group by transplanting Fisher donor kidneys into Lewis recipients. Thirty Lewis rats that received Lewis kidneys served as control group. Serum creatinine (SCr) was monitored regularly every two weeks from 14 days after transplantation. Eight rats were randomly selected by random number table method and underwent DTI examination at 4, 12, 20 weeks after modeling. DTI scans were performed on the renal cortex and medulla to measure apparent diffusion coefficient (ADC) and fractional anisotropy (FA). From the remaining 22 rats in each group, 6 rats were randomly selected and underwent pathological analysis at 4, 12, 20 weeks after modeling. Histological changes in the kidney were evaluated by chronic allograft damage index (CADI) scores. The expression of alpha-smooth muscle actin (α-SMA) and Vimentin were quantitatively measured. The differences in creatinine, DTI parameters, CADI score, α-SMA, Vimentin expression level were analyzed by two independent samples t test in two groups, the differences among CADI score, α-SMA, Vimentin expression level of the experimental group were compared using ANOVA. The correlations among DTI parameters and CADI score, α-SMA and Vimentin expression level were analyzed using Pearson analysis. Results The creatinine in the experimental group increased continuously, and the creatinine in the control group showed no significant increase. The difference in creatinine between the two groups was statistically significant from 8th week after operation (P<0.01). There was no obvious difference in the size and signal intensity of transplanted kidneys in control group at different time points. Compared with the control group, the graft kidney in the experimental group at the 4 weeks demonstrated increased signal intensity with mild increased volume of kidney, and the boundaries between cortex and medulla were not clear. The cortex and medulla showed gradually increased signal intensity, heterogeneous signal distribution and marginal haziness over time. The ADC and FA value of renal cortex and medulla in experimental group were significantly lower than those in control group at 4, 12, 20 weeks (P<0.05). The ADC and FA values of the cortex and medulla gradually decreased in the experimental group over time, while the values of the parameters in the control group did not show a significant decrease. The ADC and FA values of the cortex and medulla were negatively correlated with the scores of CADI, and the expression level of α-SMA, Vimentin in the experimental group(r=-0.50 to-0.85, P<0.01). Conclusion DTI can be an effective technique for early diagnosis of CAN and monitoring of graft fibrosis process. Key words: Kidney transplantation; Chronic allograft nephropathy; Diffusion tensor imaging; Comparative study

To determine normative diffusion values of the median nerve at several anatomic locations in healthy men and women of variable age and to compare these normative values with those in patients with carpal tunnel syndrome. After ethics board approval and written informed consent were obtained, 45 healthy volunteers (30 women, 15 men) and 15 patients (10 women, five men) were studied. Volunteers were divided into three age groups. Magnetic resonance (MR) neurography with diffusion-tensor imaging (DTI) was performed in all study participants at 3.0 T by using a single-shot echo-planar imaging sequence (repetition time msec/echo time msec, 10 123/40; b=1200 sec/mm2). Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) of the median nerve were determined by two readers at three locations: the levels of the distal radioulnar joint, pisiform bone, and hamate bone. Normative FA and ADC values were calculated for men and women, different age groups, and different anatomic locations. FA and ADC did not differ between men and women (P=.28 and P=.38, respectively). FA decreased and ADC increased when moving from proximal to distal locations (P<.001). FA decreased and ADC increased significantly with age (P<.001). There was a significant difference between healthy volunteers and patients with carpal tunnel syndrome (P<.001 for both FA and ADC). An FA threshold of 0.47 and an ADC threshold of 1.054×10(-3) mm2/sec might be used in the diagnosis of carpal tunnel syndrome. Normative diffusion values for MR neurography of the median nerve with DTI depend on the anatomic location and age but not on sex. Age-specific FA and ADC threshold values might be used to diagnose carpal tunnel syndrome.

To evaluate the feasibility of multimodal diffusion-weighted imaging (DWI) for detecting the occurrence and severity of acute kidney injury (AKI) caused by severe acute pancreatitis (SAP) in rats. SAP was induced in thirty rats by the retrograde injection of 5.0% sodium taurocholate through the biliopancreatic duct. Six rats underwent MRI of the kidneys 24h before and 2, 4, 6, and 8h after this AKI model was generated. Conventional and functional MRI sequences were used, including intravoxel incoherent motion imaging (IVIM), diffusion tensor imaging (DTI), and diffusion kurtosis imaging (DTI). The main DWI parameters and histological results were analyzed. The fast apparent diffusion coefficient (ADC) of the renal cortex was significantly reduced at 2h, as was the fractional anisotropy (FA) value of the renal cortex on DTI. The mean kurtosis (MK) values for the renal cortex and medulla gradually increased after model generation. The renal histopathological score was negatively correlated with the medullary slow ADC, fast ADC, and perfusion scores for both the renal cortex and medulla, as were the ADC and FA values of the renal medulla in DTI, whereas the MK values of the cortex and medulla were positively correlated (r = 0.733, 0.812). Thus, the cortical fast ADC, medullary MK, FADTI, and slow ADC were optimal parameters for diagnosing AKI. Of these parameters, cortical fast ADC had the highest diagnostic efficacy (AUC = 0.950). The fast ADC of the renal cortex is the core indicator of early AKI, and the medullary MK value might serve as a sensitive biomarker for grading renal injury in SAP rats. The multimodal parameters of renal IVIM, DTI, and DKI are potential beneficial for the early diagnosis and severity grading of renal injury in SAP patients. • The multimodal parameters of renal DWI, including IVIM, DTI, and DKI, may be valuable for the noninvasive detection of early AKI and the severity grading of renal injury in SAP rats. • Cortical fast ADC, medullary MK, FA, and slow ADC are optimal parameters for early diagnosis of AKI, and cortical fast ADC has the highest diagnostic efficacy. • Medullary fast ADC, MK, and FA as well as cortical MK are useful for predicting the severity grade of AKI, and the renal medullary MK value exhibits the strongest correlation with pathological scores.