Tomographic cerebral blood flow measurement during carotid surgery

Objectives:

The aim of the study was to depict regional cerebral blood flow (rCBF) during carotid cross clamping using ^99mTechnetium-hexamethylpropylene amine oxime (^TcHMPAO). This tracer rapidly passes the blood-brain barrier and is retained for hours in the brain tissue. Injecting ^TcHMPAO during surgery and performing single photon emission computer tomography (SPECT) scanning shortly after the operation thereby pictures rCBF at the time of injection.

Design:

Ongoing prospective study.

Settings:

Departments of Vascular Surgery, Neurology and Anaesthesiology, University Hospital, Rigshospitalet, Copenhagen, Denmark.

Material:

15 patients who during a period of 4 months underwent carotid endarterectomy.

Chief outcome measures:

Prior to surgery rCBF was determined using ¹³³Xe and SPECT. Intraoperatively stump pressure was measured and a bolus of ^TcHMPAO was injected for later SPECT measurement.

Main results:

We found a significant correlation between stump pressure and enhancement of side-to-side asymmetry in rCBF due to carotid cross clamping. Pronounced variations were seen in which regions were deprived of perfusion during clamping.

Conclusion:

^TcHMPAO allows tomographic assessment of CBF during carotid surgery. This method may serve as a reference tool in future research on intraoperative cerebral haemodynamics.