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Mark B. Vestergaard

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2 papers

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YNICL Journal 2021 Journal Article

Interictal pontine metabolism in migraine without aura patients: A 3 Tesla proton magnetic resonance spectroscopy study

Samaira Younis
Anders Hougaard
Casper E. Christensen
Mark B. Vestergaard
Olaf B. Paulson
Henrik B.W. Larsson
Messoud Ashina

In the pons, glutamatergic mechanisms are involved in regulating inhibitory descending pain modulation, serotoninergic neurotransmission as well as modulating the sensory transmission of the trigeminovascular system. Migraine involves altered pontine activation and structural changes, while biochemical, genetic and clinical evidence suggests that altered interictal pontine glutamate levels may be an important pathophysiological feature of migraine abetting to attack initiation. Migraine without aura patients were scanned outside attacks using a proton magnetic resonance spectroscopy protocol optimized for the pons at 3 Tesla. The measurements were performed on two separate days to increase accuracy and compared to similar repeated measurements in healthy controls. We found that interictal glutamate (i.e. Glx) levels in the pons of migraine patients (n = 33) were not different from healthy controls (n = 16) (p = 0.098), while total creatine levels were markedly increased in patients (9%, p = 0.009). There was no correlation of glutamate or total creatine levels to migraine frequency, days since the last attack, usual pain intensity of attacks or disease duration. In conclusion, migraine is not associated with altered interictal pontine glutamate levels. However, the novel finding of increased total creatine levels suggests that disequilibrium in the pontine energy metabolism could be an important feature of migraine pathophysiology.

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YNIMG Journal 2021 Journal Article

Validation of kinetic modeling of [15O]H2O PET using an image derived input function on hybrid PET/MRI

Mark B. Vestergaard
Oriol P. Calvo
Adam E. Hansen
Sverre Rosenbaum
Henrik B.W. Larsson
Otto M. Henriksen
Ian Law

In present study we aimed to validate the use of image-derived input functions (IDIF) in the kinetic modeling of cerebral blood flow (CBF) measured by [15O]H2O PET by comparing with the accepted reference standard arterial input function (AIF). Additional comparisons were made to mean cohort AIF and CBF values acquired by methodologically independent phase-contrast mapping (PCM) MRI. Using hybrid PET/MRI an IDIF was generated by measuring the radiotracer concentration in the internal carotid arteries and correcting for partial volume effects using the intravascular volume measured from MRI-angiograms. Seven patients with carotid steno-occlusive disease and twelve healthy controls were examined at rest, after administration of acetazolamide, and, in the control group, during hyperventilation. Agreement between the techniques was examined by linear regression and Bland-Altman analysis. Global CBF values modeled using IDIF correlated with values from AIF across perfusion states in both patients (p<10−6, R2=0. 82, 95% limits of agreement (LoA)=[-11. 3–9. 9] ml/100 g/min) and controls (p<10−6, R2=0. 87, 95% LoA=[-17. 1–13. 7] ml/100 g/min). The reproducibility of gCBF using IDIF was identical to AIF (15. 8%). Values from IDIF and AIF had equally good correlation to measurements by PCM MRI, R2=0. 86 and R2=0. 84, (p<10−6), respectively. Mean cohort AIF performed substantially worse than individual IDIFs (p<10−6, R2=0. 63, LoA=[-12. 8–25. 3] ml/100 g/min). In the patient group, use of IDIF provided similar reactivity maps compared to AIF. In conclusion, global CBF values modeled using IDIF correlated with values modeled by AIF and similar perfusion deficits could be established in a patient group.

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