Impact of neuroimaging in the pretreatment evaluation of early stage non-small cell lung cancer.

Background: There are limited data and conflicting guideline recommendations regarding the role of neuroimaging in the pretreatment evaluation of non-small cell lung cancer (NSCLC).

Methods: We performed a retrospective, pragmatic cohort study of patients with NSCLC diagnosed between January 1 and December 31, 2015. Eligible patients were identified from an institutional tumor registry.

Quantitative magnetic susceptibility mapping without phase unwrapping using WASSR.

The magnetic susceptibility of tissue within and around an image voxel affects the magnetic field and thus the local frequency in that voxel. Recently, it has been shown that spatial maps of frequency can be used to quantify local susceptibility if the contributions of surrounding tissue can be deconvolved. Currently, such quantitative susceptibility mapping (QSM) methods employ gradient recalled echo (GRE) imaging to measure spatial differences in the signal phase evolution as a function of echo time, from which frequencies can be deduced.

Mapping magnetic susceptibility anisotropies of white matter in vivo in the human brain at 7 T.

High-resolution magnetic resonance phase- or frequency-shift images acquired at high field show contrast related to magnetic susceptibility differences between tissues. Such contrast varies with the orientation of the organ in the field, but the development of quantitative susceptibility mapping (QSM) has made it possible to reproducibly image the intrinsic tissue susceptibility contrast. However, recent studies indicate that magnetic susceptibility is anisotropic in brain white matter and, as such, needs to be described by a symmetric second-rank tensor( ̅χ).

Multi-parametric neuroimaging reproducibility: a 3-T resource study.

Modern MRI image processing methods have yielded quantitative, morphometric, functional, and structural assessments of the human brain. These analyses typically exploit carefully optimized protocols for specific imaging targets. Algorithm investigators have several excellent public data resources to use to test, develop, and optimize their methods.

q-space and conventional diffusion imaging of axon and myelin damage in the rat spinal cord after axotomy.

Parallel and perpendicular diffusion properties of water in the rat spinal cord were investigated 3 and 30 days after dorsal root axotomy, a specific insult resulting in early axonal degeneration followed by later myelin damage in the dorsal column white matter. Results from q-space analysis (i.e.

Reproducibility of tract-specific magnetization transfer and diffusion tensor imaging in the cervical spinal cord at 3 tesla.

Damage to specific white matter tracts within the spinal cord can often result in the particular neurological syndromes that characterize myelopathies such as traumatic spinal cord injury. Noninvasive visualization of these tracts with imaging techniques that are sensitive to microstructural integrity is an important clinical goal. Diffusion tensor imaging (DTI)- and magnetization transfer (MT)-derived quantities have shown promise in assessing tissue health in the central nervous system.

Complex geometric models of diffusion and relaxation in healthy and damaged white matter.

Which aspects of tissue microstructure affect diffusion weighted MRI signals? Prior models, many of which use Monte-Carlo simulations, have focused on relatively simple models of the cellular microenvironment and have not considered important anatomic details. With the advent of higher-order analysis models for diffusion imaging, such as high angular resolution diffusion imaging (HARDI), more realistic models are necessary. This paper presents and evaluates the reproducibility of simulations of diffusion in complex geometries.

Diffusion tensor magnetic resonance imaging of Wallerian degeneration in rat spinal cord after dorsal root axotomy.

Diffusion tensor imaging (DTI) and immunohistochemistry were used to examine axon injury in the rat spinal cord after unilateral L(2)-L(4) dorsal root axotomy at multiple time points (from 16 h to 30 d after surgery). Three days after axotomy, DTI revealed a lesion in the ipsilateral dorsal column extending from the lumbar to the cervical cord. The lesion showed significantly reduced parallel diffusivity and increased perpendicular diffusivity at day 3 compared with the contralateral unlesioned dorsal column.

Measurement of T1 and T2 in the cervical spinal cord at 3 tesla.

T(1) and T(2) were measured for white matter (WM) and gray matter (GM) in the human cervical spinal cord at 3T. T(1) values were calculated using an inversion-recovery (IR) and B(1)-corrected double flip angle gradient echo (GRE) and show significant differences (p = 0.002) between WM (IR = 876 +/- 27 ms, GRE = 838 +/- 54 ms) and GM (IR = 973 +/- 33 ms, GRE = 994 +/- 54 ms).

Diffusion tensor imaging at low SNR: nonmonotonic behaviors of tensor contrasts.

Diffusion tensor imaging (DTI) provides measurements of directional diffusivities and has been widely used to characterize changes in the tissue microarchitecture of the brain. DTI is gaining prominence in applications outside of the brain, where resolution, motion and short T2 values often limit the achievable signal-to-noise ratio (SNR). Consequently, it is important to revisit the topic of tensor estimation in low-SNR regimes.

High b-value q-space diffusion-weighted MRI of the human cervical spinal cord in vivo: feasibility and application to multiple sclerosis.

Q-space analysis is an alternative analysis technique for diffusion-weighted imaging (DWI) data in which the probability density function (PDF) for molecular diffusion is estimated without the need to assume a Gaussian shape. Although used in the human brain, q-space DWI has not yet been applied to study the human spinal cord in vivo. Here we demonstrate the feasibility of performing q-space imaging in the cervical spinal cord of eight healthy volunteers and four patients with multiple sclerosis.

Multiparametric magnetic resonance imaging analysis of the corticospinal tract in multiple sclerosis.

Background/purpose: Muscle weakness is an important feature of multiple sclerosis and is responsible for much of the disability associated with that condition. Here, we describe the quantitative magnetic resonance imaging (MRI) attributes of the major intracerebral motor pathway--the corticospinal tract--in multiple sclerosis. To do so, we develop an intuitive method for creating and displaying spatially normalized tract-specific imaging data.

Effects of signal-to-noise ratio on the accuracy and reproducibility of diffusion tensor imaging-derived fractional anisotropy, mean diffusivity, and principal eigenvector measurements at 1.5 T.

Purpose: To develop an experimental protocol to calculate the precision and accuracy of fractional anisotropy (FA), mean diffusivity (MD), and the orientation of the principal eigenvector (PEV) as a function of the signal-to-noise ratio (SNR) in vivo.

Materials And Methods: A healthy male volunteer was scanned in three separate scanning sessions, yielding a total of 45 diffusion tensor imaging (DTI) scans. To provide FA, MD, and PEV as a function of SNR, sequential scans from a scan session were grouped into nonintersecting sets.

Effects of diffusion weighting schemes on the reproducibility of DTI-derived fractional anisotropy, mean diffusivity, and principal eigenvector measurements at 1.5T.

Diffusion tensor imaging (DTI) is used to study tissue composition and architecture in vivo. To increase the signal to noise ratio (SNR) of DTI contrasts, studies typically use more than the minimum of 6 diffusion weighting (DW) directions or acquire repeated observations of the same set of DW directions. Simulation-based studies have sought to optimize DTI acquisitions and suggest that increasing the directional resolution of a DTI dataset (i.

Pulsed magnetization transfer imaging with body coil transmission at 3 Tesla: feasibility and application.

Pulsed magnetization transfer (MT) imaging has been applied to quantitatively assess brain pathology in several diseases, especially multiple sclerosis (MS). To date, however, because of the high power deposition associated with the use of short, rapidly repeating MT prepulses, clinical application has been limited to lower field strengths. The contrast-to-noise ratio (CNR) of MT is limited, and this method would greatly benefit from the use of higher magnetic fields and phased-array coil reception.