Progress in cerebrovascular disease: local cerebral blood flow by xenon enhanced CT.

Abstract

A noninvasive technique for measuring local cerebral blood flow (LCBF) by xenon enhanced x-ray transmission computed tomography (CT) has been developed an reported quite extensively in recent years. In this method, nonradioactive xenon gas in inhaled and the temporal changes in radiographic enhancement produced by the inhalation are measured by sequential computed tomography. Time dependent xenon concentrations within various tissue segments in the brain are used to derive both local partition coefficient (lambda) and LCBF. An assessment of this method reveals that although it provides functional mapping of blood flow with excellent anatomic specificity, there are distinct limitations. The assumptions underlying this methodology are examined and problems associated with various potential applications of this technique are discussed.

Effect of stable xenon in room air on regional cerebral blood flow and electroencephalogram in normal baboons.

“…Thirty-eight minutes after the start of inhalation, CBF was estimated to be 26.4 ± 10.7 ml/100 g/min below baseline values. Gur et al 23 also reported an initial increase and subsequent decrease of CBF in baboons after several minutes of inhalation. Similar experiences were reported by Meyer et al 24 in patients and were believed to be due to pharmacologic effects.…”

“…This is also known for halogenated anesthetics. 23 The increase in CBF during mild hypotension may substantiate the uncoupling of CBF from metabolic regulatory processes with inhalation of Xe s . The increase in rCBF caused by administration of Xe s during mild hypotension (autoregulation test, CBF 4) indicated that Xe s even breaks the autoregulatory action.…”

Xenon-enhanced computed tomography compared with [14C]iodoantipyrine for normal and low cerebral blood flow states in baboons.

“…- 25 Two CT brain levels were selected for each study, and two nonenhanced baseline scans were obtained at each level. Then the inhaled gas was switched to a 32% xenon/ 68% oxygen mixture.…”

Management of lateral skull base tumours

“…1): After its entry into the carotid canal at the skullbase, the midportion of the vertical ICA is anteromedial to the basal turn of the cochlea. In the distal part of the vertical segment near the genu, the ICA is just deep to the eustachian tube orifice, posteromedial to the glenoid fossa, and inferomedial to the tensor tympani muscle 8 . The horizontal segment of the ICA travels overlies the foramen lacerum travelling obliquely in a lateral-to-medial direction from the genu to the point of intracranial intradural entry at the anterior clinoid process.…”

“…There still remains risk of delayed ischaemia which can be ascertained with cerebral blood flow reserve studies such as xenon CT scan or Technetium -99 m hexamethylpropyleneamine oxime ( 99m Tc-HMPAO). [7][8][9] Others techniques include PET scan, single photon emission CT (SPECT) scan, and functional MR imaging testing, none of which have gained broad acceptance but show great promise. Proper planning and decision on management of the ICA should be done preoperatively.…”