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Purpose: The relationship of magnetic resonance imaging (MRI) measures of rotator cuff intramuscular fatty infiltration (FI) to shoulder range of motion (ROM) and strength are not well understood. Our purpose was to determine if supraspinatus quantitative Dixon fat fraction has superior correlation to shoulder ROM and strength as compared to semiquantitative Goutallier grade.Methods: Thirty-seven study subjects received shoulder MRI; and measurement of ipsilateral shoulder forward flexion ROM, abduction ROM and abduction strength. Supraspinatus Dixon fat fraction was measured on 6-point Dixon MRI by 2 diagnostic radiology residents. Supraspinatus Goutallier grade was assessed on T1-weighted MRI by 2 musculoskeletal radiologists. Questionnaires recorded demographics. Based on characteristics, study subjects were divided into 3 groups: Group 1, neither shoulder pain nor full-thickness supraspinatus tendon (SST) tear (n = 17; mean age, 63.0 ± 10.1 years); Group 2, positive complaint of shoulder pain but without full-thickness SST tear (n = 7; mean age, 57.4 ± 9.9 years); Group 3, positive complaint of shoulder pain and full-thickness SST tear (n = 13; mean age, 63.6 ± 8.1 years). One-way analysis of variance compared groups. Spearman (rho) rank order correlation was performed to determine correlation of supraspinatus Dixon fat fraction, or Goutallier grade, with measures of ROM and strength for the study population. Reliability analyses were performed for Dixon fat fraction and Goutallier grade.Results: No significant differences were present among groups for age. Significant differences existed among groups for forward flexion ROM (P= 0.001), abduction ROM (P < 0.001), Dixon fat fraction (P = 0.004) and Goutallier grade (P = 0.012). Dixon fat fraction showed statistically significant inverse correlations with forward flexion ROM (rho = -0.47; P = 0.005), abduction ROM (rho = -0.35, P = 0.041), and abduction strength (rho = -0.42; P = 0.013). Goutallier grade demonstrated weak inverse correlation that lacked statistical significance (P > 0.05) for the same measures. Dixon fat fraction showed strong interobserver and intraobserver reliability with intraclass correlation coefficients of 0.956 and 0.999, respectively. Goutallier grade showed poor interobserver (kappa, 0.188) and moderate intraobserver (kappa, 0.608) reliability.Conclusion: Supraspinatus Dixon fat fraction has superior correlation to shoulder ROM and strength relative to Goutallier grade on MRI. [ABSTRACT FROM AUTHOR]

Rationale and Objectives: The automated segmentation of organs and tissues throughout the body using computed tomography and magnetic resonance imaging has been rapidly increasing. Research into many medical conditions has benefited greatly from these approaches by allowing the development of more rapid and reproducible quantitative imaging markers. These markers have been used to help diagnose disease, determine prognosis, select patients for therapy, and follow responses to therapy. Because some of these tools are now transitioning from research environments to clinical practice, it is important for radiologists to become familiar with various methods used for automated segmentation.Materials and Methods: The Radiology Research Alliance of the Association of University Radiologists convened an Automated Segmentation Task Force to conduct a systematic review of the peer-reviewed literature on this topic.Results: The systematic review presented here includes 408 studies and discusses various approaches to automated segmentation using computed tomography and magnetic resonance imaging for neurologic, thoracic, abdominal, musculoskeletal, and breast imaging applications.Conclusion: These insights should help prepare radiologists to better evaluate automated segmentation tools and apply them not only to research, but eventually to clinical practice. [ABSTRACT FROM AUTHOR]

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Molecular and functional imaging is increasingly being used to guide radiotherapy (RT) management and target delineation. This review summarizes existing data in several disease sites of various functional imaging modalities, chiefly positron emission tomography/computed tomography (PET/CT), with respect to RT target definition and management. For gliomas, differentiation between postoperative changes and viable tumor is discussed, as well as focal dose escalation and reirradiation. Head and neck neoplasms may also benefit from precise PET/CT-based target delineation, especially for cancers of unknown primary; focal dose escalation is also described. In lung cancer, PET/CT can influence coverage of tumor volumes, dose escalation, and adaptive management. For cervical cancer, PET/CT as an adjunct to magnetic resonance imaging planning is discussed, as are dose escalation and delineation of avoidance targets such as the bone marrow. The emerging role of choline-based PET for prostate cancer and its impact on dose escalation is also described. Lastly, given the essential role of PET/CT for target definition in lymphoma, phase III trials of PET-directed management are reviewed, along with novel imaging modalities. Taken together, molecular and functional imaging approaches offer a major step to individualize radiotherapeutic care going forward. [ABSTRACT FROM AUTHOR]

Abstract: Background: Motor cortex stimulation (MCS) is a potentially effective treatment for chronic neuropathic pain. The neural mechanisms underlying the reduction of hyperalgesia and allodynia after MCS are not completely understood. Objective: To investigate the neural mechanisms responsible for analgesic effects after MCS. We test the hypothesis that MCS attenuates evoked blood oxygen-level dependent signals in cortical areas involved in nociceptive processing in an animal model of chronic neuropathic pain. Methods: We used adult female Sprague–Dawley rats (n = 10) that received unilateral electrolytic lesions of the right spinal cord at the level of C6 (SCL animals). In these animals, we performed magnetic resonance imaging (fMRI) experiments to study the analgesic effects of MCS. On the day of fMRI experiment, 14 days after spinal cord lesion, the animals were anesthetized and epidural bipolar platinum electrodes were placed above the left primary motor cortex. Two 10-min sessions of fMRI were performed before and after a session of MCS (50 μA, 50 Hz, 300 μs, for 30 min). During each fMRI session, the right hindpaw was electrically stimulated (noxious stimulation: 5 mA, 5 Hz, 3 ms) using a block design of 20 s stimulation off and 20 s stimulation on. A general linear model-based statistical parametric analysis was used to analyze whole brain activation maps. Region of interest (ROI) analysis and paired t-test were used to compare changes in activation before and after MCS in these ROI. Results: MCS suppressed evoked blood oxygen dependent signals significantly (Family-wise error corrected P < 0.05) and bilaterally in 2 areas heavily implicated in nociceptive processing. These areas consisted of the primary somatosensory cortex and the prefrontal cortex. Conclusions: These findings suggest that, in animals with SCL, MCS attenuates hypersensitivity by suppressing activity in the primary somatosensory cortex and prefrontal cortex. [Copyright &y& Elsevier]

Abstract: The mechanical processes that underlie mild traumatic brain injury from physical insults are not well understood. One aspect in particular that has not been examined is the tissue fluid, which is known to be critical in the mechanical function of other organs. To investigate the contributions of solid–fluid interactions to brain tissue mechanics, we performed confined compression tests, that force the extracellular fluid (ECF) to flow in the direction of the deformation, on 6.35mm diameter, 3mm long cylindrical samples excised from various regions of rat brains. Two types of tests in deformation control, (1) quasi-static, slow and moderate constant strain rate tests at 0.64×10−5/s, 0.001/s and 1/s to large strains and (2) several applications of slow linear deformation to 5% strain each followed by stress relaxation are employed to explore the solid–fluid interaction. At slow and moderate compressive strain rates, we observed stress peaks in the applied strain range at about 11%, whose magnitudes exhibited statistically significant dependence on strain rate. These data suggest that the ECF carries load until the tissue is sufficiently damaged to permit pathological fluid flow. Under the slow ramp rate in the ramp-relaxation cycles protocol, commonly used to estimate permeability, the stress relaxes to zero after the first cycle, rather than to a non-zero equilibrium stress corresponding to the applied strain, which further implicates mechanical damage. Magnetic resonance imaging (MRI) of changes in tissue microstructure during confined compression, before and after compression, provides further evidence of tissue damage. The solid–fluid interactions, reflected in the morphology of the stress–stretch curves and supported by the MRI data, suggest that increases in hydrostatic pressure in the ECF may contribute to mechanical damage of brain tissue. [Copyright &y& Elsevier]

Background: Basilar artery thrombosis remains a significant clinical problem, and no reproducible animal model has been established to study the stroke within the vertebrobasilar distribution. We report a study designed to pilot test a novel model of brainstem stroke in rabbits, created by selective endovascular occlusion of the basilar artery. Methods: Basilar artery occlusion was induced in 8 New Zealand white rabbits by injection of the autologous clot through the microcatheter positioned within the distal vertebral artery. Animals were divided into subgroups (I and II) based on the length of produced ischemia (3 and 6 hours, respectively). Magnetic resonance (MR) imaging of the brain and MR angiography of the intracranial vessels were performed before the procedure, and at 3 hours after induced ischemia for groups I and II, with continued imaging up to 6 hours for group II, with diffusion-weighted images acquired approximately every 30 minutes. Animals were killed at the end of the 3-hour (group I) or 6-hour (group II) ischemia time. Results: Brainstem stroke was successfully induced in all animals, with pathological changes documented in all cases. The earliest changes of ischemia on MR diffusion-weighted images were identified at only 4.5 hours of basilar artery occlusion. Conclusion: These results suggest that a reproducible model of brainstem stroke can be induced in rabbits using selective endovascular occlusion of the basilar artery. The availability of such a model, integrated with state-of-the-art imaging techniques, holds promise for preclinical investigations of emergent therapeutic approaches in stroke. [Copyright &y& Elsevier]

Elevated plasma neurofilament light chain (NfL) is associated with dementia though underlying mechanisms remain unknown. We examined cross-sectional relationships of time-dependent plasma NfL with selected brain structural magnetic resonance imaging (sMRI) prognostic markers of dementia. The sample was drawn from the Healthy Aging in Neighborhoods of Diversity Across the Life Span (HANDLS) study, selecting participants with complete v 1 (2004–2009) and v 2 (2009–2013) plasma NfL exposure and ancillary sMRI data at v scan (2011–2015, n = 179, mean v 1 to v scan time: 5.4 years). Multivariable-adjusted linear regression models were conducted, overall, by sex, and race, correcting for multiple testing with q-values. NfL (v1) was associated with larger WMLV (both Log e transformed), after 5–6 years' follow-up, overall (β = +2.131 ± 0.660, b = +0.29, p = 0.001, and q = 0.0029) and among females. NfLv 2 was linked to a 125 mm3 lower left hippocampal volume (p = 0.004 and q = 0.015) in reduced models, mainly among males, as was observed for annualized longitudinal change in NfL (δNfL bayes). Among African American adults, NfL v1 was inversely related to total, gray and white matter volumes. Plasma NfL may reflect future brain pathologies in middle-aged adults. [ABSTRACT FROM AUTHOR]

Objective: The purpose of this study was to examine whether the diffusion tensor imaging (DTI) technique can be used as a modality to represent the structural deformation in the in vivo genioglossus (GG) muscle fibers with oral appliances (OAs). Study Design: Three healthy subjects were recruited for the pilot study. A custom-made OA, which is modified from a tongue retaining device (TRD), was constructed for each subject before the DTI acquisitions. Recordings were made with and without OAs to compare the GG muscle fiber deformation. Result: DTI provided good resolution of tongue muscle fibers in vivo and successful isolation of each muscle fiber bundle. In particular, the GG muscle fiber deformation due to OAs was clearly visualized. Conclusions: This DTI technique may be used not only to identify the individual myoarchitecture, but also to assess muscle fiber deformations in vivo, such as constriction, dilatation, and rotation with OAs. Clinical studies for OSA patients will be the next step. [Copyright &y& Elsevier]

Plasma neurofilament light chain (NfL)'s link to dementia may be mediated through white matter integrity (WMI). In this study, we examined plasma NfL's relationships with diffusion tensor magnetic resonance imaging markers: global and cortical white matter fractional anisotropy (FA) and trace (TR). Plasma NfL measurements at 2 times (v 1 : 2004–2009 and v 2 : 2009–2013) and ancillary dMRI (v scan : 2011–2015) were considered (n = 163, mean time v 1 to v scan = 5.4 years and v 2 to v scan : 1.1 years). Multivariable-adjusted regression models, correcting for multiple-testing revealed that, overall, higher NfL v1 was associated with greater global TR (β ± SE: +0.0000560 ± 0.0000186, b = 0.27, p = 0.003, q = 0.012), left frontal WM TR (β ± SE: + 0.0000706 ± 0.0000201, b ± 0.30, p = 0.001, q = 0.0093) and right frontal WM TR (β ± SE: + 0.0000767 ± 0.000021, b ± 0.31, p < 0.001, q = 0.0093). These associations were mainly among males and White adults. Among African American adults only, NfL v2 was associated with greater left temporal lobe TR. "Tracking high" in NfL was associated with reduced left frontal FA (Model 2, body mass index-adjusted: β ± SE:-0.01084 ± 0.00408, p = 0.009). Plasma NfL is a promising biomarker predicting future brain white matter integrity (WMI) in middle-aged adults. [ABSTRACT FROM AUTHOR]

Purpose: Prostate brachytherapy (PB) entails the placement of radioactive sources throughout the entire prostate gland to treat localized cancer. Typically, the target volume in PB encompasses the entire prostate gland because of the inability to localize the cancer and the multifocal nature of this malignancy. However, because of the unique biochemical nature of the prostate gland, recent advances in magnetic resonance spectroscopic imaging (MRSI) of the prostate have allowed precise delineation of the cancer location within the prostate gland. This report reveals our initial experience of MRSI-guided PB.Methods: An MRSI study was obtained in 15 favorable-risk (prostate-specific antigen level ≤10 ng/mL, Gleason score ≤6, and clinical Stage ≤T2a) patients before their scheduled PB. The results of this study were used to internally map 7 × 7 × 9-mm volumes of prostate tissue to assign cancerous areas a higher dose of radiation. Such tumor-bearing areas had a low citrate/(choline+creatine) ratio consistent with cancer. On the basis of the anatomic MRI and MRSI correlation, three-dimensional coordinates were assigned to the locations of MRSI-defined cancer. The entire target volume was treated to 145 Gy using 125I. Abnormal citrate regions, termed the biologic tumor volume, were prescribed a dose of 130% of the target volume dose (188 Gy) to dose escalate in the abnormal citrate regions while respecting the normal radiation tolerances of the surrounding areas. Three-dimensional treatment planning was used to perform the implant.Results: Of the 15 prostate cancer patients evaluated, all had successful three-dimensional MRSI acquisition before their scheduled PB procedure. In 14 of the 15 patients planned with MRSI, the data were successfully incorporated into their treatment planning and were used to increase the radiation dose prescription to 130% in the MRSI-defined volumes. In 1 patient, MRSI revealed significant multifocal disease that made focal boosts impractical. Postimplant dosimetry confirmed a median V100 of 95% (range 89–98%) in the 15 evaluated patients for the prescription dose of 145 Gy to the target volume. Furthermore, the median BTV100 for the abnormal citrate region was 90% (range 80–100%) as determined by postimplant dosimetry. Urethral and rectal dose-volume histograms were within normal limits. Morbidity was comparable with that for conventionally treated patients.Conclusion: MRSI offers a promising new approach for the delivery of ionizing radiation in PB. Although this series was small and with a short follow-up, MRSI-guided implants are feasible and warrant further investigation as a means of improving the therapeutic ratio in PB. [Copyright &y& Elsevier]

• Greater RDW v1 was associated with poorer WMI, among males only, particularly in terms of lower mean global fractional anisotropy (FA). • No such associations were found for anemia and δRDW (overall or sex-specific), or for RDW exposures among females and the non-anemic group. Anemia (blood hemoglobin [Hb] <13 g/dL among males; <12 g/dL among females) and elevated red cell distribution width (RDW) are potential risk factors for reduced brain white matter integrity (WMI), reflected by lower fractional anisotropy or increased mean diffusivity. Cross-sectional data with exposure-outcome lag time was used, whereby hematological exposures (RDW and Hb) and covariates were compiled from the Healthy Aging in Neighborhoods of Diversity across the Life Span (HANDLS) study with available visit 1 (v 1 ; 2004–2009) and/or v 2 (2009–2013) data; while diffusion tensor magnetic resonance imaging (dMRI) outcome data were collected at HANDLS SCAN visit (v scan : 2011–2015, n = 214, mean follow-up from v 1 ±SD: 5.6 ± 1.8 year). Multivariable-adjusted linear regression analyses were conducted, overall, stratifying by sex, and further restricting to the nonanemic for RDW exposures in part of the analyses. Among males, RDW (v1) was linked with lower global mean fractional anisotropy (standardized effect size b = −0.30, p = 0.003, q < 0.05; basic model), an association only slightly attenuated with further covariate adjustment. Anemia was not a risk factor for poor WMI, independently of RDW. Ultimately, pending further longitudinal evidence, initial RDW appears to be associated with poorer WMI among males. [ABSTRACT FROM AUTHOR]

Pronounced spin phase artifacts appear in diffusion-weighted imaging (DWI) with only minor subject motion. While DWI data corruption is often identified as signal drop out in diffusion-weighted (DW) magnitude images, DW phase images may have higher sensitivity for detecting subtle subject motion. This article describes a novel method to return a metric of subject motion, computed using an image texture analysis of the DW phase image. This Phase Image Texture Analysis for Motion Detection in dMRI (PITA-MDD) method is computationally fast and reliably detects subject motion from diffusion-weighted images. A threshold of the motion metric was identified to remove motion-corrupted slices, and the effect of removing corrupted slices was assessed on the reconstructed FA maps and fiber tracts. Using a motion-metric threshold to remove the motion-corrupted slices results in superior fiber tracts and fractional anisotropy maps. When further compared to a state-of-the-art magnitude-based motion correction method, PITA-MDD was able to detect comparable corrupted slices in a more computationally efficient manner. In this study, we evaluated the use of DW phase images to detect motion corruption. The proposed method can be a robust and fast alternative for automatic motion detection in the brain with multiple applications to inform prospective motion correction or as real-time feedback for data quality control during scanning, as well as after data is already acquired. [ABSTRACT FROM AUTHOR]

Abstract: In this study we investigated the functional connectivity in 23 Mild TBI (mTBI) patients with and without memory complaints using resting state fMRI in the sub-acute stage of injury as well as a group of control participants. Results indicate that mTBI patients with memory complaints performed significantly worse than patients without memory complaints on tests assessing memory from the Automated Neuropsychological Assessment Metrics (ANAM). Altered functional connectivity was observed between the three groups between the default mode network (DMN) and the nodes of the task positive network (TPN). Altered functional connectivity was also observed between both the TPN and DMN and nodes associated with the Salience Network (SN). Following mTBI there is a reduction in anti-correlated networks for both those with and without memory complaints for the DMN, but only a reduction in the anti-correlated network in mTBI patients with memory complaints for the TPN. Furthermore, an increased functional connectivity between the TPN and SN appears to be associated with reduced performance on memory assessments. Overall the results suggest that a disruption in the segregation of the DMN and the TPN at rest may be mediated through both a direct pathway of increased FC between various nodes of the TPN and DMN, and through an indirect pathway that links the TPN and DMN through nodes of the SN. This disruption between networks may cause a detrimental impact on memory functioning following mTBI, supporting the Default Mode Interference Hypothesis in the context of mTBI related memory deficits. [Copyright &y& Elsevier]

Highlights: [•] We developed an automatic rat brain extraction algorithm, called the Rat Brain Deformable model method (RBD). [•] RBD is based on the deformable surface model. [•] RBD outperformed the existing rat brain extraction methods. [•] RBD achieved a higher accuracy of >92% volume overlap for brain extraction. [•] RBD was also robust against signal inhomogeneity in the images. [Copyright &y& Elsevier]