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In-Depth Information
MDCT-based trabecular bone microstructure parameters and
finite element models
have shown to improve the prediction of bone strength beyond DXA-based BMD
and revealed pharmacotherapy effects, which were partly not captured by BMD.
Furthermore, recent studies demonstrated that quantitative magnetic resonance
imaging (MRI) including proton single-voxel magnetic resonance spectroscopy
(
1
H-MRS) and chemical shift-based water-fat imaging techniques quantifying bone
marrow fat content at the spine may provide complementary information for
diagnosing osteoporosis and assessing vertebral fracture risk.
1 Introduction
This chapter focuses on osteoporosis imaging at the spine and is structured into
ve
parts: After a background section, imaging techniques and post-processing methods
are outlined to correctly diagnose osteoporotic vertebral fractures. Subsequently,
bone mineral density (BMD) measurements, which have traditionally been used for
the assessment of osteoporosis, are presented. Measurements of bone microstruc-
ture and bone marrow fat content at the spine, which have been already used or
have been emerging for predicting osteoporosis-related fracture risk and evaluating
therapy response beyond BMD, are discussed in the last sections.
2 Background
Osteoporosis is de
ned as a skeletal disorder characterized by compromised bone
strength predisposing an individual to an increased risk for fracture [
1
]. Bone
strength primarily re
ects the integration of bone mineral density (BMD) and bone
quality including bone microstructure, turnover, and damage accumulation (e.g.
microfractures). Osteoporotic subjects show a loss of BMD and deterioration of
bone quality (Fig.
1
). Osteoporosis is classi
fl
ed as either primary or secondary.
Primary osteoporosis results from the cumulative bone loss due to ageing and the
corresponding changes of sex hormones. It is further divided in type I and type II
osteoporosis. Type I osteoporosis affects women after menopause, while type II
osteoporosis can be found in elderly men as well as women and is also named senile
osteoporosis. Secondary osteoporosis results from medications (e.g. glucocorti-
coids) or other conditions (e.g. hypogonadism). The most common form is the
primary, type I (postmenopausal) osteoporosis.
The clinically most important fracture sites are the radius, hip and spine. It has
been demonstrated that osteoporotic vertebral and hip fractures are associated with
a reduced quality of life [
2
,
3
]. Furthermore, vertebral and hip fractures are asso-
ciated with an increased mortality [
4
6
]. In 2010, 22 million women and 5.5 million
men were estimated to have osteoporosis in the European Union [
7
]. The number of
-
