technetium-tc-99m-exametazime and Reperfusion-Injury

Little is known about the effect of spontaneous reperfusion of human cerebral infarcts. Single photon emission computerised tomography (SPECT) data were analysed from a study using 99Tc(m) HMPAO (99Tc(m) hexamethylpropyleneamine oxime) in human cerebral infarction for the frequency of reperfusion and to see if it affected infarct size, oedema, haemorrhagic transformation, or functional outcome.. Fifty sequential cases of ischaemic stroke were studied with 124 99Tc(m) HMPAO SPECT at around one day, one week, and three months after stroke along with detailed clinical and functional assessments.. Visually apparent reperfusion occurred in 14 of 50 patients (28%) with a mean delay of 5.8 days and reperfusion was seen in seven others in whom it was identified on the basis of changes in perfusion deficit volume. It occurred in 13 of 23 embolic events but only in three of 23 other events. In only two cases did spontaneous reperfusion occur early enough to preserve tissue or function. Reperfusion did not otherwise reduce infarct size, or improve clinical or functional outcome, and was not associated with oedema but an association with haemorrhagic transformation was suggested. Reperfusion significantly decreased the apparent perfusion defect as measured by SPECT one week from the ictus, but was mostly non-nutritional and transient. The mean volume of tissue preserved by nutritional reperfusion was 10 cm3, but this was unequally distributed between cases. Late washout of 99Tc(m) HMPAO from areas of hyperaemic reperfusion may be a good prognostic marker but is a rare phenomenon and too insensitive to be of general applicability.. Spontaneous reperfusion after cerebral infarction occurs in 42% of cases within the first week but is associated with clinical improvement in only 2%. It has few adverse consequences although it may be associated with haemorrhagic transformation.

Topics: Activities of Daily Living; Adult; Aged; Aged, 80 and over; Brain; Cerebral Infarction; Female; Humans; Hyperemia; Male; Middle Aged; Prognosis; Prospective Studies; Radiopharmaceuticals; Reperfusion Injury; Reproducibility of Results; Sensitivity and Specificity; Technetium Tc 99m Exametazime; Time Factors; Tomography, Emission-Computed, Single-Photon

This study examines the topographic profile of reperfusion into ischaemic tissue following reversible middle cerebral artery (MCA) occlusion. Autoradiographic images of both ischaemia and reperfusion were prepared from brain sections following transient ischaemia induced by endothelin-1 application to the exposed MCA in anaesthetised rats. Blood flow changes were assessed using double tracer autoradiography with 99mTc-exametazime during ischaemia (5 min) and 14C-iodoantipyrine during reperfusion (2 h). Following a significant ischaemic insult, reperfusion was relatively homogeneous within MCA territory but incomplete at 2 h. There was evidence for differential reperfusion in the cortex and caudate nucleus, and increased collateral supply from the anterior cerebral artery.

Topics: Animals; Antipyrine; Autoradiography; Cerebral Arteries; Cerebrovascular Circulation; Collateral Circulation; Endothelins; Ischemic Attack, Transient; Male; Organotechnetium Compounds; Oximes; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Technetium Tc 99m Exametazime

Topics: Adult; Graft Rejection; Humans; Middle Aged; Organometallic Compounds; Oximes; Pancreas; Pancreas Transplantation; Postoperative Complications; Radionuclide Imaging; Reperfusion Injury; Technetium; Technetium Tc 99m Exametazime