MRI-based Methods for Quantification of Fat and Fatty Acid Composition. Validation and Applications.

Lena Trinh

Forskningsoutput: AvhandlingDoktorsavhandling (sammanläggning)

231 Nedladdningar (Pure)

Sammanfattning

The interest of in vivo measurements of fat has increased over the years due to the increasing prevalence of obesity and obesity-related conditions such as diabetes, cardiovascular disease, and fatty liver. The relationship between the accumulation of adipose tissue within the different depots and organs of the body, and the risk of developing numerous diseases, has been investigated and established. However, the role of the fatty acid composition (FAC) of the adipose tissue in various diseases is yet to be settled and understood. In this thesis, MR-based methods for in vivo quantification of fat content and fatty acid composition have been investigated. Possible applications have been explored as well.
Today, the most widely used methods for assessing fat are based on magnetic resonance imaging (MRI). In some cases, MRI is even considered gold standard and one of the most common MRI-methods is water/fat imaging. Water/fat imaging has the possibility of measuring both the adipose tissue volume in depots designated for fat storage and the fat and adipose tissue within organs or body parts such as the liver or skeletal muscle. For example, the fat accumulation in skeletal muscle of patients with lymphedema was estimated using water/fat imaging in Paper II. Excess fat was found in both the intermuscular and intramuscular compartments of the edematous limbs. The excess accumulation of fat within the intermuscular and intramuscular compartments has not been demonstrated in any previous study of lymphedema.
Although widely used, water/fat imaging may be limited in some applications if a very high spatial resolution is desirable. In Paper I, an alternative T2-based MRI method for estimating fat content using high spatial resolution MR images of the calf was explored. Different fitting algorithms were investigated and compared to low resolution water/fat imaging (reference method). While all approaches resulted in qualitatively adequate fat fraction images, only a non-linear least squares based fitting approach showed good agreement and correlation to the reference method.
Recently, MR-based methods for estimating the chemical composition of fat, i.e. the FAC, have been introduced. In contrast to the gold standard technique for measuring FAC (gas chromatography), MR-based approaches are non-invasive and offer spatial information without the need for multiple measurements. In this thesis, MR-based methods for in vivo FAC measurements were compared and validated against FAC quantification gas chromatography analysis of subcutaneous adipose tissue (Paper III). Especially the MRI-based approach resulted in promising results as high correlations to gas chromatography were found.
Several studies have suggested an association between FAC and the development of e.g. cardiovascular disease. In a previous study, a higher prevalence of hypertension (one of the strongest risk factors for cardiovascular disease) was found among Iraqi-born men resident in Sweden compared to Swedish-born men. In this thesis, the FAC of the subcutaneous and visceral adipose tissue of Iraqi- and Swedish-born men was measured and compared using the MRI-based method (Paper IV). Significantly different FAC was found between the studied groups. In general, higher proportions of polyunsaturated fat and lower proportions of saturated and monounsaturated fat were found among the Iraqi-born men.
Originalspråkengelska
KvalifikationDoktor
Tilldelande institution
  • Institutionen för translationell medicin
Handledare
  • Månsson, Sven, handledare
  • Brorson, Håkan, Biträdande handledare
  • Peterson, Pernilla, Biträdande handledare
  • Olsson, Lars E, Biträdande handledare
  • Svensson, Jonas, Biträdande handledare
Tilldelningsdatum2020 juni 5
UtgivningsortLund
Förlag
ISBN (tryckt)978-91-7619-929-9
StatusPublished - 2020

Bibliografisk information

Defence details
Date: 2020-06-05
Time: 09:15
Place: Agardh föreläsningssal, CRC, Jan Waldenströms gata 35, Skånes Universitetssjukhus i Malmö
External reviewer(s)
Name: Lundberg, Peter
Title: professor
Affiliation: Linköping University

Ämnesklassifikation (UKÄ)

  • Radiologi och bildbehandling

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