Abstract
Magnetic resonance neurography (MRN) has been used extensively to study pathological conditions affecting the peripheral nervous system (PNS). However, tissue damage is assessed qualitatively with little information regarding the underlying pathophysiological processes involved. Magnetisation transfer ratio (MTR) is a quantitative magnetic resonance imaging method which is sensitive to tissue macromolecular content and may therefore have an important role in the study of pathologies affecting the PNS. This study explored the feasibility of obtaining reliable MTR measurements in the proximal lumbar plexus of healthy volunteers using MRN to identify and segment each lumbar segment (L2–L5) and regions (preganglionic, ganglionic and postganglionic). Reproducibility of the MTR measurements and of the segmentation method were assessed from repeated measurements (scan-rescan), and from the reanalysis of images (intra- and inter-rater assessment), by calculating the coefficient of variation (COV). In all segments combined (L2–L5), mean (± SD) MTR was 30.5 (± 2.4). Scan-rescan, intra- and inter-rater COV values were 3.2%, 4.4% and 5.3%, respectively. One-way analysis of variance revealed a statistically significant difference in MTR between the preganglionic and postganglionic regions in all lumbar segments. This pilot study in healthy volunteers demonstrates the feasibility of obtaining reliable MTR measurements in the proximal lumbar plexus, opening up the possibility of studying a broad spectrum of neurological conditions in vivo.
Highlights
Magnetic resonance neurography (MRN) has been used extensively to study pathological conditions affecting the peripheral nervous system (PNS)
We have demonstrated the feasibility of obtaining reliable Magnetisation transfer ratio (MTR) measurements in the proximal lumbar plexus in healthy volunteers using a 3 T magnetic resonance imaging (MRI) system and commercially available software and hardware; the acquisition and analysis protocol presented in this work maybe translated to the clinical settings to study a large number of pathological conditions affecting the lumbar p lexus[20,21]
The rationale behind this study was the lack of quantitative MRI protocols that can be used to obtain more specific information about the underlying pathophysiological processes involved in common pathologies affecting the lumbar plexus
Summary
Magnetic resonance neurography (MRN) has been used extensively to study pathological conditions affecting the peripheral nervous system (PNS). One-way analysis of variance revealed a statistically significant difference in MTR between the preganglionic and postganglionic regions in all lumbar segments This pilot study in healthy volunteers demonstrates the feasibility of obtaining reliable MTR measurements in the proximal lumbar plexus, opening up the possibility of studying a broad spectrum of neurological conditions in vivo. In healthy v olunteers[8], chronic inflammatory demyelinating p olyradiculoneuropathy[9], multiple sclerosis[10] and diabetic and amyloidotic p olyneuropathy[11,12] These studies have demonstrated that the increased T2w signal intensity typically observed in MRN investigations may not always reflect an increase in T2 relaxation time and alteration in proton density, supporting the notion that macromolecular structures may play an important role[9,10,11,12]. The ability to obtain reliable MTR measurements in the peripheral nerves of the lower extremities as well as other anatomical locations such as the lumbar plexus for example, which is known to be affected by a plethora of neurological c onditions[20,21], can have profound clinical implications both in terms of diagnosis and approach to treatment
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