sodium-pertechnetate-tc-99m and Brain-Ischemia

The cause of hemispheric swelling and high intracranial pressure after acute subdural hematoma is unknown, yet this is a major cause of death related to this condition. To investigate whether vascular engorgement is the cause of this form of hemisphere swelling, we have autoradiographically mapped regional cerebral blood flow before and after removal of acute subdural hematoma in a rat model. Hyperemia was patchy and infrequent. The major cause of the significant hemisphere swelling seen after hematoma removal was enlargement of the zone of focal tissue ischemia and edema under the hematoma.

Topics: Acute Disease; Animals; Autoradiography; Brain Edema; Brain Ischemia; Brain Mapping; Cerebrovascular Circulation; Hematoma, Subdural; Male; Postoperative Complications; Radionuclide Imaging; Rats; Rats, Inbred Strains; Sodium Pertechnetate Tc 99m

A combined measurement of regional cerebral blood flow (r CBF) and volume (r CBV) by SPECT was performed in 15 patients with ischaemic cerebral infarction. For measurement of r CBF 99mTc-HMPAO was used, and for r CBV 99mTc-labelled red blood cells. Patients with acute or subacute cerebral infarction (n = 10) showed elevation of r CBV whereas r CBF was either reduced or elevated. Patients with chronic cerebral infarction (n = 5) showed reduction of both r CBF and r CBV. The combined measurement of both r CBF and r CBV by SPECT allows imaging and semiquantitative evaluation of haemodynamic changes in ischaemic cerebral infarction at various stages. The resulting data may be helpful in describing the pathophysiologic compensatory mechanisms.

Topics: Aged; Aged, 80 and over; Blood Volume; Blood Volume Determination; Brain Ischemia; Cerebral Infarction; Cerebrovascular Circulation; Humans; Middle Aged; Organometallic Compounds; Oximes; Sodium Pertechnetate Tc 99m; Technetium; Technetium Tc 99m Exametazime; Tomography, Emission-Computed

Topics: Animals; Blood-Brain Barrier; Brain Ischemia; Evans Blue; Female; Heart Arrest; Models, Neurological; Radionuclide Imaging; Rats; Rats, Inbred Strains; Sodium Pertechnetate Tc 99m

In 15 patients with a recent ischaemic cerebral vascular accident computerized tomography (CT) of the brain was normal whereas scintigraphy, performed at the same time, clearly showed the ischaemic area. These discordant findings may be interpreted as false-negative CT results. Factors such as the time elapsed between the cerebral accident and the CT examination, and the use or non-use of an intravenous contrast injection are discussed. It seems that the key factor is the proximity of the ischaemic lesion to the surface of the brain: cortical necrosis is undetectable at CT but distinctly visible at scintigraphy.

Topics: Adult; Aged; Aged, 80 and over; Brain Ischemia; Female; Humans; Male; Middle Aged; Necrosis; Radionuclide Imaging; Sodium Pertechnetate Tc 99m; Tomography, X-Ray Computed

The results of an evaluation of the perfusion scintigraphy findings of 350 hospitalised neurological patients and 55 more strictly selected neurosurgical patients with cerebrovascular complaints, revealed an accuraty of 83%, a sensitivity of 89%, and a specificity of 83%. The selection of the patients had no influence on the results as a whole. Compared with contrast-medium angiography, incorrect diagnosis must be expected in 17% of the cases. This includes erroneous negative findings in 10% of the cases. Grounds for misinterpretations are suggested, and the biological and methodological limitations of the method are set forth.

Topics: Brain Ischemia; Carotid Artery Diseases; Cerebrovascular Disorders; Humans; Intracranial Aneurysm; Radionuclide Angiography; Sodium Pertechnetate Tc 99m; Subarachnoid Hemorrhage

The regional concentrations of nine radiochemicals were measured in rat brain after induction of cerebral ischemia to identify tracers concentrated by brain undergoing selective neuronal necrosis. Transient (30 minute) forebrain ischemia was produced in the rat; 24 hours after cerebral recirculation the radiochemicals were injected intravenously and allowed to circulate for 5 hours. The brain concentrations of the radiochemicals in dissected regions were determined by scintillation counting. Forebrain ischemia of this nature will produce extensive injury to striatal neurons but will spare the great majority of neocortical neurons at 24 hours. The regional concentrations of these radiochemicals varied considerably in both control and ischemic animals. In postischemic animals, 4 radionuclides (63Ni, 99TcO4, 22Na, and [3H]tetracycline) were concentrated in the irreversibly damaged striatum in amounts ranging from 1.4 to 2.4 times greater than in normal tissue. The concentrations of 65Zn, 59Fe, 32PO4, and 147Pm in postischemic brain were similar to or less than those in normal brain. The concentration of [14C]EDTA was increased in injured and uninjured brain of postischemic rats. Autoradiographic analysis of the distribution patterns of some of these ions in normal animals showed that 99TcO4, 22Na, 65Zn, and 59Fe were distributed more uniformly throughout the brain than were 32PO4, 63Ni, and 147Pm. At 24 or 48 hours after ischemia, 63Ni, 99TcO4, and 22Na were preferentially concentrated in the damaged striatum and hippocampus, whereas 65Zn, 59Fe, 32PO4, and 147Pm did not accumulate in irreversibly injured tissue. Of the radiochemicals tested to date, Ni, TcO4, and tetracycline may be useful for diagnosing ischemic brain injury in humans, using positron emission tomography.

Topics: Animals; Brain; Brain Ischemia; Edetic Acid; Iron Radioisotopes; Male; Nickel; Promethium; Radioisotopes; Rats; Rats, Inbred Strains; Sodium Pertechnetate Tc 99m; Sodium Radioisotopes; Tetracycline; Zinc Radioisotopes

Topics: Adolescent; Adult; Aged; Brain; Brain Ischemia; Cerebrovascular Disorders; Female; Humans; Ischemic Attack, Transient; Male; Middle Aged; Radionuclide Imaging; Sodium Pertechnetate Tc 99m; Tomography, X-Ray Computed

155 patients with ischemic completed stroke of varying severity and outcome have been evaluated by radionuclide cerebral angiography with analysis of regional time-activity curves. Two parameters have been evaluated: area under the upslope of the curve (Aup) reflecting regional blood flow rate and moment of the whole curve reflecting tracer circulation time (rABCT) Combination of these two methods ensured increased detection of perfusion asymmetries.

Topics: Blood Circulation Time; Blood Flow Velocity; Brain; Brain Ischemia; Cerebrovascular Circulation; Humans; Radionuclide Imaging; Sodium Pertechnetate Tc 99m

The induction of global cerebral ischaemia in laboratory animals is difficult to accomplish and has been even more difficult to verify. Most reported verification methods suffer from lack of sensitivity or from being traumatic and highly invasive. We describe a non-traumatic global cerebral ischaemia verification technique which is quantitative, simple, and highly sensitive. Radioactive technetium-99m pertechnetate is injected intravenously during the ischaemic phase of an experiment and the appearance of radioactivity within the animal's head is quantitated using a gamma camera and nuclear medicine computer. Radioactivity levels below the visual perception threshold are readily measured, thus providing a high degree of confidence in assessing the partial or total nature of cerebral ischaemia.

Topics: Animals; Brain Ischemia; Cerebrovascular Circulation; Computers; Disease Models, Animal; Radionuclide Imaging; Rats; Scintillation Counting; Sodium Pertechnetate Tc 99m

The relation between perfusion defects shown by radionuclide angiography and static brain scan positivity was evaluated in patients with ischaemic completed stroke at various intervals from the onset of symptoms. An inverse relation between radionuclide angiography and static scan positivity was found for the period within 15 days of the onset of symptoms. The possible relation between changes in perfusion and static brain scan positivity is discussed.

Topics: Brain Ischemia; Cerebral Angiography; Cerebrovascular Circulation; Cerebrovascular Disorders; Humans; Radionuclide Imaging; Sodium Pertechnetate Tc 99m; Technetium