umu.sePublikationer
Ändra sökning
RefereraExporteraLänk till posten
Permanent länk

Direktlänk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Simulating effects of brain atrophy in longitudinal PET imaging with an anthropomorphic brain phantom
Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Umeå universitet, Samhällsvetenskapliga fakulteten, Enheten för demografi och åldrandeforskning (CEDAR). (Umeå Center for Functional Brain Imaging)ORCID-id: 0000-0001-6169-5836
Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).ORCID-id: 0000-0002-3731-3612
Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).ORCID-id: 000-0001-5227-8117
Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Umeå universitet, Samhällsvetenskapliga fakulteten, Enheten för demografi och åldrandeforskning (CEDAR). Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital, Hvidovre, Denmark.ORCID-id: 0000-0002-4458-6475
2017 (Engelska)Ingår i: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 62, nr 13, s. 5213-5227Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

In longitudinal positron emission tomography (PET), the presence of volumetric changes over time can lead to an overestimation or underestimation of the true changes in the quantified PET signal due to the partial volume effect (PVE) introduced by the limited spatial resolution of existing PET cameras and reconstruction algorithms. Here, a 3D-printed anthropomorphic brain phantom with attachable striata in three sizes was designed to enable controlled volumetric changes. Using a method to eliminate the non-radioactive plastic wall, and manipulating BP levels by adding different number of events from list-mode acquisitions, we investigated the artificial volume dependence of BP due to PVE, and potential bias arising from varying BP. Comparing multiple reconstruction algorithms we found that a high-resolution ordered- subsets maximization algorithm with spatially variant point-spread function resolution modeling provided the most accurate data. For striatum, the BP changed by 0.08% for every 1% volume change, but for smaller volumes such as the posterior caudate the artificial change in BP was as high as 0.7% per 1% volume change. A simple gross correction for striatal volume is unsatisfactory, as the amplitude of the PVE on the BP differs depending on where in the striatum the change occurred. Therefore, to correctly interpret age-related longitudinal changes in the BP, we must account for volumetric changes also within a structure, rather than across the whole volume. The present 3D-printing technology, combined with the wall removal method, can be implemented to gain knowledge about the predictable bias introduced by the PVE differences in uptake regions of varying shape.

Ort, förlag, år, upplaga, sidor
Institute of Physics Publishing (IOPP), 2017. Vol. 62, nr 13, s. 5213-5227
Nyckelord [en]
longitudinal, PET, partial volume effect, brain phantom, dopamine
Nationell ämneskategori
Radiologi och bildbehandling
Forskningsämne
radiofysik
Identifikatorer
URN: urn:nbn:se:umu:diva-136030DOI: 10.1088/1361-6560/aa6e1bISI: 000402879700001PubMedID: 28561014OAI: oai:DiVA.org:umu-136030DiVA, id: diva2:1108839
Tillgänglig från: 2017-06-13 Skapad: 2017-06-13 Senast uppdaterad: 2018-06-09Bibliografiskt granskad
Ingår i avhandling
1. Aerobic fitness and healthy brain aging: cognition, brain structure, and dopamine
Öppna denna publikation i ny flik eller fönster >>Aerobic fitness and healthy brain aging: cognition, brain structure, and dopamine
2017 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Alternativ titel[sv]
Aerobisk träning och hjärnans hälsosamma åldrande : kognition, hjärnstruktur och dopamin
Abstract [en]

Background: Performing aerobic exercise and maintaining high levels of aerobic fitness may have positive effects on both brain structure and function in older adults. Despite decades of research however, there is still a rather poor understanding of the neurocognitive mechanisms explaining the positive effects of aerobic exercise on cognition. Changes in prefrontal gray matter as well as dopaminergic neurotransmission in striatum are both candidate neurocognitive mechanisms. The main aims of this thesis are: 1. To investigate the effects of aerobic exercise and fitness on cognition and magnetic resonance imaging (MRI) derived gray matter volumes using data from a 6 month physical exercise intervention in older adults (Study I). 2. To simulate the effect of atrophy in longitudinal positron emission tomography (PET) which could pose a challenge to interpreting changes in longitudinal PET imaging (Study II). 3. To study the influence of aerobic exercise and fitness on the dopamine D2-receptor (D2R) system in striatum using [11C]raclopride PET as a potential mechanism for improved cognition (Study III).

Results: In Study I, aerobic exercise was found to improve cognitive performance in a broad, rather than domain-specific sense. Moreover, aerobic fitness was related to prefrontal cortical thickness, and improved aerobic fitness over 6 months was related to increased hippocampal volume. In Study II, we identified areas in the striatum vulnerable to the effect of shrinkage, which should be considered in longitudinal PET imaging. Finally, in Study III, the effect of being aerobically fit, and improving fitness levels was found to impact dopaminergic neurotransmission in the striatum, which in turn mediated fitness-induced improvements in working memory updating performance.

Conclusion: The findings in this thesis provide novel evidence regarding the neurocognitive mechanisms of aerobic exercise-induced improvements in cognition, and impacts the interpretation of longitudinal PET imaging. Performing aerobic exercise and staying aerobically fit at an older age have positive effects on cognition and brain systems important for memory and cognition. Specifically, fitness-induced changes to the dopaminergic system stands out as one novel neurocognitive mechanism explaining the positive effects of aerobic fitness on working-memory performance in healthy older adults.

Ort, förlag, år, upplaga, sidor
Umeå: Umeå Universitet, 2017. s. 81
Serie
Umeå University medical dissertations, ISSN 0346-6612 ; 1908
Nyckelord
Aerobic exercise, VO2, working memory, executive function, freesurfer, striatum, dopamine, D2-receptors, [11C]raclopride
Nationell ämneskategori
Neurovetenskaper Idrottsvetenskap
Identifikatorer
urn:nbn:se:umu:diva-139056 (URN)978-91-7601-753-1 (ISBN)
Disputation
2017-09-29, Sal 933, Building 3B, Norrland University Hospital, Umeå, 09:35 (Engelska)
Opponent
Handledare
Tillgänglig från: 2017-09-08 Skapad: 2017-09-06 Senast uppdaterad: 2018-06-09Bibliografiskt granskad

Open Access i DiVA

fulltext(1126 kB)109 nedladdningar
Filinformation
Filnamn FULLTEXT01.pdfFilstorlek 1126 kBChecksumma SHA-512
1796d862ecd3f402a60891e570c8634a0a29896b9efc053f6249d65f72fa184da31bba9402fb08c76162e881ba11d5ce3f5c69cb35fed588248c1c4da5c34397
Typ fulltextMimetyp application/pdf

Övriga länkar

Förlagets fulltextPubMed

Personposter BETA

Jonasson, LarsAxelsson, JanRiklund, KatrineBoraxbekk, Carl-Johan

Sök vidare i DiVA

Av författaren/redaktören
Jonasson, LarsAxelsson, JanRiklund, KatrineBoraxbekk, Carl-Johan
Av organisationen
Diagnostisk radiologiUmeå centrum för funktionell hjärnavbildning (UFBI)Enheten för demografi och åldrandeforskning (CEDAR)Radiofysik
I samma tidskrift
Physics in Medicine and Biology
Radiologi och bildbehandling

Sök vidare utanför DiVA

GoogleGoogle Scholar
Totalt: 109 nedladdningar
Antalet nedladdningar är summan av nedladdningar för alla fulltexter. Det kan inkludera t.ex tidigare versioner som nu inte längre är tillgängliga.

doi
pubmed
urn-nbn

Altmetricpoäng

doi
pubmed
urn-nbn
Totalt: 490 träffar
RefereraExporteraLänk till posten
Permanent länk

Direktlänk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf