Mean transit time as an index of cerebral perfusion pressure in experimental systemic hypotension

Abstract

Early diagnosis of cerebrovascular disease requires the accurate identification of brain regions with compromised cerebral perfusion pressure (CPP). Current clinical measures of CPP are invasive and lack regional information. Dynamic contrast-enhanced imaging provides a means of looking at regional cerebral hemodynamics. The purpose of this study was to determine if any of the parameters associated with dynamic contrast-enhanced imaging could be used as an index for CPP under graded systemic hypotension in a rabbit model. Cerebral blood flow (CBF), cerebral blood volume, mean transit time (MTT), and cerebrovascular reserve (CVR) were measured using Computed Tomography Perfusion in three groups: normotensive (n = 14), mild hypotensive (n = 9), and moderate hypotensive (n = 6). MTT demonstrated the strongest correlation with CPP (ρ = -0.642, P < 0.05). CBF was the only other parameter to demonstrate a statistically significant correlation (ρ = 0.575, P < 0.05). CVR is gaining momentum for diagnosing cerebrovascular disease; however, the technique requires patients to be given a hemodynamic challenge, which could aggravate symptoms and even trigger stroke. The results of this study suggest that the use of MTT, not requiring hemodynamic manipulation, is more sensitive to subtle changes in CPP, as would occur in the early stages of cerebrovascular disease.

Brain Hemodynamic Changes Associated with Chronic Cerebrospinal Venous Insufficiency Are Not Specific to Multiple Sclerosis and Do Not Increase Its Severity

“…Indeed, MTT was increased in patients with MS, independent of the possible coexistence of CCSVI, which suggests a possible role of regional cerebral perfusion in MS course and pathogenesis, regardless of venous malformations. In this respect, MTT is closely related to cerebral perfusion pressure (27) and to penumbra entity (28), and our findings are in good agreement with previous histopathologic evidence in MS that shows vascular occlusion (29) and/or hypoxia-like tissue injury (30). Besides focal white-matter lesions, MS brain tissue also displays abnormalities in the NAWM.…”

Regional resting state perfusion variability and delayed cerebrovascular uniform reactivity in subjects with chronic carotid artery stenosis

“…Similar results in healthy volunteers were obtained by Pantano and coworkers (1984) in PET study. The MTT in the frontal, parietal and temporal cortices grey matter was within the normal range (3-5 s), suggesting relatively balanced circulation and perfusion pressure (Schumann et al, 1988;Murphy et al, 2011). The moderate CBF decline in subjects with chronic carotid stenosis is in line with other reports by our team and others (Szarmach et al, 2017a;Szarmach et al, 2017b;Niesen et al, 2004;Trojanowska et al, 2006).…”

Improved Hemodynamic Parameters in Middle Cerebral Artery Infarction After Decompressive Craniectomy

“…The time between symptom onset and surgery was 44.6±25.2 hours, and 14 (51.9%) patients underwent surgery <48 hours of ictus. The median preoperative Glasgow Coma Scale score was 10 (interquartile range, 9-11), the median National Institute of Health Stroke Scale was 20 (interquartile range, [18][19][20][21], and the mean brain MLS on preoperative CT scan was 4.5±7.6 mm. In total, 19 (70.3%) patients showed signs of a hyperdense MCA, and 10 (37%) patients had a left hemisphere stroke.…”

“…19 Specifically, the PCT parameters most sensitive to subtle changes in cerebral perfusion pressure were MTT and CBF. 20 In an experimental study, DC led to an increase in cortical perfusion caused by leptomeningeal arteries. 8 In general, these findings may explain our results of increased CBF and reduced MTT after surgery, especially in the PIZ.…”