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Characterization of trabecular bone density with ultra-short echo-time MRI at 1.5, 3.0 and 7.0 T - comparison with micro-computed tomography


Wurnig, Moritz C; Calcagni, Maurizio; Kenkel, David; Vich, Magdalena; Weiger, Markus; Andreisek, Gustav; Wehrli, Felix W; Boss, Andreas (2014). Characterization of trabecular bone density with ultra-short echo-time MRI at 1.5, 3.0 and 7.0 T - comparison with micro-computed tomography. NMR in Biomedicine, 27(10):1159-1166.

Abstract

The goal of this study was to test the potential of ultra-short echo-time (UTE) MRI at 1.5, 3.0 and 7.0 T for depiction of trabecular bone structure (of the wrist bones), to evaluate whether T2 * relaxation times of bone water and parametric maps of T2 * of trabecular bone could be obtained at all three field strengths, and to compare the T2 * relaxation times with structural parameters obtained from micro-computed tomography (micro-CT) as a reference standard. Ex vivo carpal bones of six wrists were excised en bloc and underwent MRI at 1.5, 3.0 and 7.0 T in a whole-body MR imager using the head coil. A three-dimensional radial fat-suppressed UTE sequence was applied with subsequent acquisitions, with six different echo times TE of 150, 300, 600, 1200, 3500 and 7000 µs. The T2 * relaxation time and pixel-wise computed T2 * parametric maps were compared with a micro-computed-tomography reference standard providing trabecular bone structural parameters including porosity (defined as the bone-free fraction within a region of interest), trabecular thickness, trabecular separation, trabecular number and fractal dimension (Dk ). T2 * relaxation curves and parametric maps could be computed from datasets acquired at all field strengths. Mean T2 * relaxation times of trabecular bone were 4580 ± 1040 µs at 1.5 T, 2420 ± 560 µs at 3.0 T and 1220 ± 300 µs at 7.0 T, when averaged over all carpal bones. A positive correlation of T2 * with trabecular bone porosity and trabecular separation, and a negative correlation of T2 * relaxation time with trabecular thickness, trabecular number and fractal dimension, was detected (p < 0.01 for all field strengths and micro-CT parameters). We conclude that UTE MRI may be useful to characterize the structure of trabecular bone, comparable to micro-CT.

Abstract

The goal of this study was to test the potential of ultra-short echo-time (UTE) MRI at 1.5, 3.0 and 7.0 T for depiction of trabecular bone structure (of the wrist bones), to evaluate whether T2 * relaxation times of bone water and parametric maps of T2 * of trabecular bone could be obtained at all three field strengths, and to compare the T2 * relaxation times with structural parameters obtained from micro-computed tomography (micro-CT) as a reference standard. Ex vivo carpal bones of six wrists were excised en bloc and underwent MRI at 1.5, 3.0 and 7.0 T in a whole-body MR imager using the head coil. A three-dimensional radial fat-suppressed UTE sequence was applied with subsequent acquisitions, with six different echo times TE of 150, 300, 600, 1200, 3500 and 7000 µs. The T2 * relaxation time and pixel-wise computed T2 * parametric maps were compared with a micro-computed-tomography reference standard providing trabecular bone structural parameters including porosity (defined as the bone-free fraction within a region of interest), trabecular thickness, trabecular separation, trabecular number and fractal dimension (Dk ). T2 * relaxation curves and parametric maps could be computed from datasets acquired at all field strengths. Mean T2 * relaxation times of trabecular bone were 4580 ± 1040 µs at 1.5 T, 2420 ± 560 µs at 3.0 T and 1220 ± 300 µs at 7.0 T, when averaged over all carpal bones. A positive correlation of T2 * with trabecular bone porosity and trabecular separation, and a negative correlation of T2 * relaxation time with trabecular thickness, trabecular number and fractal dimension, was detected (p < 0.01 for all field strengths and micro-CT parameters). We conclude that UTE MRI may be useful to characterize the structure of trabecular bone, comparable to micro-CT.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Institute of Anatomy
04 Faculty of Medicine > University Hospital Zurich > Clinic for Diagnostic and Interventional Radiology
04 Faculty of Medicine > Institute of Biomedical Engineering
04 Faculty of Medicine > University Hospital Zurich > Clinic for Reconstructive Surgery
Dewey Decimal Classification:570 Life sciences; biology
170 Ethics
610 Medicine & health
Language:English
Date:4 August 2014
Deposited On:13 Aug 2014 13:47
Last Modified:05 Apr 2016 18:00
Publisher:Wiley-Blackwell
ISSN:0952-3480
Publisher DOI:https://doi.org/10.1002/nbm.3169
PubMed ID:25088271

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