Perfusion changes following elective surgery in the elderly

Purpose / Introduction
As society ages and medical technology advances, more and more elderly undergo elective surgery. However, older patients have an
increased risk of postoperative cognitive dysfunction, leading to impaired quality of life and an increased chance of becoming dependent 1.
The pathophysiology of these long‐term side effects is poorly understood. New imaging biomarkers may be used to study the postoperative
changes and evaluate the efficacy between different surgical or anesthetic strategies 1. In this study we explore the cerebral
blood flow ﴾CBF﴿ changes following elective surgery using arterial spin labeling ﴾ASL﴿ perfusion MRI.
Subjects and Methods
Data were drawn from the Biomarker Development for Postoperative Cognitive Impairment in the Elderly ﴾BioCog﴿ study. Sixty‐five elderly
﴾71.7 ± 5.2 yrs, 73.9% M﴿ were scanned before and approximately 3 months after various types of elective surgery, excluding brain surgery
and history of dementia. A background suppressed 2D EPI pseudo‐continuous ASL scan was performed, with labeling duration 1650 ms
and post‐labeling delay slice‐range 1525‐2225 ms. CBF maps were processed2 and transformed into standard space3 using ExploreASL4.
We investigated global CBF changes, cognitive decline regions and the spatial coefficient of variation ﴾CoV﴿5.
Results
CBF decreased with 11.4% in the white matter ﴾WM, p=0.004﴿ and with 7.6% in the gray matter ﴾GM, p=0.017﴿ ﴾Table 1﴿. We did not
identify regional CBF changes ﴾data not shown﴿, suggesting that CBF decreased to a similar degree across the brain. The 8.8% WB CBF
decrease was correlated with baseline WB CBF ﴾r=0.63, p<0.001﴿.
The spatial CoV did not change ﴾p=0.179﴿, implying that there were no major macro‐vascular changes. Visually, the CBF decrease was
subtle and slightly asymmetrical ﴾Figure 1﴿. Figure 2 shows that CBF decreased in the majority of the individuals. This effect seems to be
stronger for higher baseline CBF values, whereas for lower CBF baseline values there were also patients whose CBF increased.
Discussion / Conclusion
We identified global CBF decreases across the brain after elective surgery, which was related with baseline CBF. Future studies are
encouraged to confirm these explorative findings in larger samples, investigate the apparent perfusion asymmetry and whether subgroups
can be defined with different degrees of CBF changes. Such an analysis may differentiate to what extent our findings are related to the type
or duration of surgery or anesthetics. Furthermore, the clinical relevance of these changes should be investigated by studying long‐term
adverse outcomes after surgery such as postoperative cognitive dysfunction1.