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Ronnie Wirestam

Professor

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MAGNETIC RESONANCE IMAGING FOR NONINVASIVE ANALYSIS OF FAT STORAGE IN MIGRATORY BIRDS

Författare

  • Ronnie Wirestam
  • Timmy Fagerlund
  • Mikael Rosén
  • Anders Hedenström

Summary, in English

Many bird species migrate long distances without any food intake and must optimize storage of energy with respect to minimization of aerodynamic drag. To contribute to the understanding of this issue, we investigated, by magnetic resonance imaging (MRI), spatial distributions of body fat during the accumulation process before migration. We collected data from 12 Lesser Whitethroats (Sylvia curruca), 9 European Robins (Erithacus rubecula), 8 Blackcaps (Sylvia atricapilla), and 5 Willow Warblers (Phylloscopus trochilus). On average, each bird was examined 3.2 times. Adipose tissue was Visualized using T1-weighted spin-echo MRI at 1.5 T. Fat-containing pixels were identified by an image-segmentation procedure. Data were analyzed with respect to (1) fat distribution within the body, (2) relationship between frontal surface area and fat mass increase, (3) fat mass increase in comparison with increase in total body mass, and (4) fat mass in relation to standardized visual classification of fat deposits. Fat increase was reflected by a larger frontal area, though adipose tissue was not deposited equally along the length of the bird. Slices with largest frontal area showed relatively low fractions of fat. Frontal area increased less than expected from conventional geometrical models, which indicates that the body shape is altered. The increase in total body mass was generally higher than the total fat mass increase, which indicates that other tissue, most likely flight muscle, can metabolize rapidly in correlation with fat accumulation. In Blackcap, total fat mass was not linearly related to standardized fat-deposit classes. Received 31 August 2007, accepted 7 June 2008.

Avdelning/ar

  • Medicinsk strålningsfysik, Lund
  • Biologiska institutionen
  • Evolutionär ekologi

Publiceringsår

2008

Språk

Engelska

Sidor

965-971

Publikation/Tidskrift/Serie

The Auk

Volym

125

Issue

4

Dokumenttyp

Artikel i tidskrift

Förlag

Oxford University Press

Ämne

  • Radiology, Nuclear Medicine and Medical Imaging

Nyckelord

  • migratory birds
  • migration
  • magnetic resonance imaging
  • fuel load
  • adipose tissue
  • fat storage

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 0004-8038