QSM in canine model of acute cerebral ischemia: A pilot study

Abstract

In the present study, we investigated the potential of QSM to assess the physiological state of cortical tissue in the middle cerebral artery occlusion canine model of a cerebral ischemia. Methods: Experiments were performed in 8 anesthetized canines. Gradient echo, perfusion, and DWI data of brains at normal and ischemic states were acquired. In the postprocessed susceptibility and quantitative cerebral blood flow maps, changes in values within the middle cerebral artery-fed cortical territories were quantified both on the ischemic and normal contralateral hemisphere side. Results: QSM values in critically ischemic tissue were significantly different from contralateral values-namely, susceptibility increase was observed in the cases in which cerebral perfusion was maintained above the threshold of neuronal death. Furthermore, the data indicates presence of a significant correlation between the changes in susceptibility values, cerebral perfusion, and the infarct volume and pial collateral scores. Additionally, our data suggests that difference in cortical susceptibility is prospectively indicative of the infarct growth rate. Conclusion: In an experimental permanent middle cerebral artery occlusion model, QSM was shown to correlate with the functional parameters characterizing viability of ischemic tissue, thus warranting further research on its ability to provide complementary information during acute stroke MRI examinations in humans.

Quantitative Evaluation of Oxygen Extraction Fraction Changes in the Monkey Brain during Acute Stroke by Using Quantitative Susceptibility Mapping

“…Compared to the contralateral hemisphere of the brain, an increase in magnetic susceptibility was seen in prominent cerebral vessels of injured regions in rodent brains with transient cerebral ischemia, and the regions of decreased susceptibility were observed at 24 h and 48 h after reperfusion, as reported previously [7]. In the subacute (1 day after stroke insult) phase of a canine model with pMCAO, increased susceptibility was detected in the infarct region of some animals in the study group with relatively high perfusion, while decreased susceptibility was found in the areas with decreased ADC and severe hypoperfusion in the other animals of the group [8]. As seen in the present study's monkey model of stroke, the magnetic susceptibility in the lesion area was significantly higher than that in the contralateral area during the hyperacute phase, which could be explained by increased oxygen extraction leading to higher concentrations of deoxyhemoglobin in the veins, as reported in a previous QSM study of stroke rodents [7].…”

“…QSM changes in ischemic brains have been reported previously in studies of acute stroke animal models [7,8] and patients [31]. Compared to the contralateral hemisphere of the brain, an increase in magnetic susceptibility was seen in prominent cerebral vessels of injured regions in rodent brains with transient cerebral ischemia, and the regions of decreased susceptibility were observed at 24 h and 48 h after reperfusion, as reported previously [7].…”

“…Susceptibility-weighted imaging (SWI) has been used to assess the abnormal magnetic susceptibility of the brain (e.g., for hemorrhage due to stroke or traumatic injury) [5,6]. QSM has recently attracted greater interest in stroke research, as it might be able to provide unique information to assess the tissue viability in ischemic hypoperfusion areas of the brain [7][8][9][10][11], as compared to diffusion and perfusion MRI, which is often used to examine the brain tissues at risk in clinical practice or research Life 2023, 13, 1008. https://doi.org/10.3390/life13041008 https://www.mdpi.com/journal/life of animal models [12][13][14][15][16][17]. It has also been suggested that the increase and decrease in magnetic susceptibility in the stroke brain might be related to the tissue viability status after stroke, as reported in a recent study of a canine model of stroke [8].…”

Quantitative susceptibility mapping as a measure of cerebral oxygenation in neonatal piglets

“…There is a growing body of work on the application of QSM in cerebral ischemia in both preclinical models and patients. [39][40][41][42][43][44] In the present study we used QSM to measure changes in the magnetic susceptibility of venous blood across a range of oxygenation states. While the linear relation between the concentration of deoxyhemoglobin and venous susceptibility has been previously reported, [16][17][18][19] ours is the first study to report a direct relationship between venous susceptibility and brain tissue PO 2 .…”