<p>Lipids and sodium (<sup>23</sup>Na) are two essential components of the
human body. They play a role in almost all biological systems. However, an
increase in their levels is associated with metabolic diseases. The elevation
of their contents can cause similar health disorders. Examples of prevalent
disorders that share an increase of musculoskeletal lipids and <sup>23</sup>Na
are hypertension and diabetes. However, the relationship between in vivo
lipid and sodium levels in pathophysiology has not been studied enough and
therefore is still unclear. Additionally, the available quantification methods to facilitate such
a study may not be practical. They are either invasive, not sensitive enough,
or require an impractical measurement time.</p>
<p>Therefore, in this work, our aims were to develop practical in
vivo methods to quantify the absolute sodium concentration as well as the
concentration of each lipid component individually, and to study the
correlation between them within the skeletal muscles.</p>
<p>Since lipids and <sup>23</sup>Na have different nuclear magnetic
resonance properties, their quantification by magnetic resonance (MR)
techniques face different challenges. Thus, we optimized different MR
spectroscopic imaging (MRSI) techniques for lipids and <sup>23</sup>Na. </p>
<p>Our proposed proton MRSI was able to provide eight lipid fat fraction
(FF) maps representing each musculoskeletal lipid component (fatty acid)
detected by our MRSI technique, and demonstrated a superior sensitivity compared to the conventional
MR imaging methods.</p>
<p>For <sup>23</sup>Na, our developed <sup>23</sup>Na-MRSI was able to
measure and map the absolute <sup>23</sup>Na concentration with values agreeing
with those reported previously in biopsy studies, and with a high repeatability
(CV < 6 %) within significantly shorter acquisition time compared to other
available techniques.</p>
<p> Finally,
the <sup>23</sup>Na concentration and the fat fractions of each lipid component
within healthy skeletal muscles were measured and correlated using our
developed MRSI methods. Our findings suggest a positive regional relationship between <sup>23</sup>Na
and lipids and negative correlation between <sup>23</sup>Na and BMI under
healthy conditions.</p>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/12425366 |
| Date | 16 June 2020 |
| Creators | Ahmad Abdurahman M. Alhulail (8933363) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/FAT_AND_SODIUM_QUANTIFICATION_AND_CORRELATION_BY_MRSI/12425366 |
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