Magnetization transfer and diffusion tensor imaging in dogs with intervertebral disk herniation

Abstract

Background: Quantitative magnetic resonance imaging (QMRI) techniques of magnetization transfer ratio (MTR) and diffusion tensor imaging (DTI) provide microstructural information about the spinal cord. Objective: Compare neurologic grades using the modified Frankel scale with MTR and DTI measurements in dogs with thoracolumbar intervertebral disk herniation (IVDH). Animals: Fifty-one dogs with thoracolumbar IVDH. Methods: Prospective cohort study. Quantitative MRI measurements of the spinal cord were obtained at the region of compression. A linear regression generalized estimating equations model was used to compare QMRI measurements between different neurological grades after adjusting for age, weight, duration of clinical signs, and lesion location. Results: Grade 5 (.79 × 10 −3 mm 2 /s [median], .43−.91 [range]) and axial (1.47 × 10 −3

MRI diffusion tensor imaging scalar values in dogs with intervertebral disc herniation: A comparison between manual and semiautomated region of interest methods

“…It has been shown that FA will transiently increase with the presence of vasogenic edema 32 . In a previous study, FA was significantly lower in dogs with T2‐weighted intramedullary hyperintensity 7 . Therefore, the presence of vasogenic edema in combination with other pathologic processes (gliosis, inflammation, hemorrhage, or malacia) could negate the utility of FA in dogs with IVDH.…”

“…First, the anatomic locations of spinal cord segments included in this study were variable. It is known that DTI values will vary between spinal cord segments 7 . This also applies to the age and weight variation between the dogs.…”

“…Scalar values acquired from DTI serve as sensitive and noninvasive tools to assess myelin and axons and have been shown to correlate with histopathologic findings 2–4 . Several studies in dogs have evaluated DTI in vivo to assess how values can be applicable in clinical settings 5–10 . Wang‐Leandro et al.…”

“…[2][3][4] Several studies in dogs have evaluated DTI in vivo to assess how values can be applicable in clinical settings. [5][6][7][8][9][10] Wang-Leandro et al found that dogs with long-term neurological deficits had lower apparent diffusion coefficient (ADC) values than controls. 9 In dogs with intervertebral disc herniation (IVDH), fractional anisotropy (FA) has been shown to have a similar sensitivity to assess deep pain in predicting clinical outcome.…”

Preliminary study on the assessment of early cartilage degeneration by quantitative ultrashort echo time magnetic resonance imaging in vivo

“…Many in vitro studies have shown that UTE-T1ρ enables the quantitative assessment of short T2 tissues in the musculoskeletal system, and UTE-T1ρ values increase with structural changes in short T2 tissues (14)(15)(16)(17)(18). The magnetization transfer ratio (MTR) provides a measure of the magnetization exchange rate of hydrogen protons bound to macromolecules such as collagen and free water (19). The UTE-MTR values have been used to evaluate the pools of protons indirectly by analyzing the interactions between the bound and pore water proton pools (20,21).…”