Radionuclide Cerebral Angiography Research Articles

Investigation of blood perfusion and metabolic activity of brain tumours in adults by using 99mTc-methoxyisobutylisonitrile

(i) To examine blood perfusion and metabolic activity of various brain tumours using radionuclide cerebral angiography (RCA) and single-photon emission tomography (SPET) after a single dose of Tc-methoxyisobutylisonitrile (MIBI). (ii) To examine if the inclusion of RCA can improve insight into the relative contribution of tumour perfusion to the uptake of MIBI shown by SPET, and to improve evaluation of tumour biology. (iii) To determine the value and the roles of MIBI in the management of brain tumour patients. Fifty adult patients (38 male, 12 female) with a total of 56 intracranial space-occupying lesions have been included prospectively, 37 of which were newly diagnosed and the remaining with signs of recurrence/rest of earlier resected and irradiated brain tumours. The control group consisted of nine volunteers with no evidence of organic cerebral disease. Scintigraphic examination consisted of a dynamic first-pass study lasting 60 s (3 s/frame) and two SPET studies (60 projections each, 25 s/projection), starting 15 min and 2 h after intravenous injection of MIBI. Regions of interest of the tumour and normal brain tissue were drawn on RCA and both early and delayed SPET slices. The following tumour/brain activity ratios have been calculated: (i) tumour perfusion index (P); (ii) early uptake index (E); (iii) delayed uptake index (D); and(iv) retention index (R). Analogous indices have been calculated from the same examinations performed in controls, reflecting maximal physiologic regional variations of perfusion and uptake in brain tissue. Mean P of various brain tumours (low-grade gliomas 0.98, anaplastic gliomas 1.14, glioblastoma multiforme 1.20, metastases 1.09, lymphomas 1.08) differ little from each other and do not exceed maximal physiologic regional variations of cerebral perfusion (1.33), with the exception of meningioma (1.87, F=2.83, P=0.015). The receiver operating characteristics curve analysis of P showed that for the cut-off value of 1.45 the sensitivity for distinguishing meningioma from other tumours is 75%, specificity 87%, positive predictive value 33% and negative predictive value 97%. Mean E of malignant brain tumours (8.3, n=31, 23 primary, eight secondary), except anaplastic gliomas (3.5, n=5), differed significantly (P=0.02) from those of benign gliomas (3, n=9) but not from that of meningioma (11.9, n=4). The cut-off value for distinguishing malignant from benign lesions on the basis of E set at 4.8 resulted in sensitivity 67%, specificity 75%, accuracy 70%, positive predictive value 80% and negative predictive value 60%. D and R showed tendency of wash-out of MIBI from meningiomas, but otherwise did not improve the results substantially. Integrated results of RCA and SPET with Tc-MIBI indicate that blood perfusion, blood-tumour barrier permeability and metabolic activity of the tumour are all very important for the resultant uptake shown by SPET. If the perfusion index is less than 1.45, then meningioma can be ruled out. Early SPET is recommendable for distinguishing glioblastoma from low-grade gliomas, as a complement to standard magnetic resonance imaging and/or computed tomography.

Brain death: Determination with brain stem evoked potentials and radionuclide isotope studies

Thirty-three patients fulfilling the clinical criteria for brain death were tested by Brainstem Auditory Evoked Potentials (BAEP) and Radionuclide Cerebral Angiography and Brain Perfusion Studies. There was a significant correlation between the BAEP and radionuclide study outcomes. All patients with absence of BAEP showed no cerebral perfusion. These findings, added to the clinical findings, resulted in a final diagnosis of brain death in all patients. It is concluded that BAEP and Radionuclide Cerebral Perfusion studies are useful adjuncts for proving that brain death has really occurred.

The community hospital-based stroke programs in north carolina, oregon and new york—V. Stroke diagnosis: Factors influencing the diagnostic evaluation of patients following acute stroke

Among the 4129 patients of the Community Hospital-based Stroke Program, 30% had an unspecified stroke diagnosis. Since specific diagnosis and, perhaps, eventual treatment, derives in part from diagnostic testing, we examined the effect of clinical condition, geographic and demographic factors on the incidence of certain diagnostic tests after acute stroke. In this multivariable analysis, race, sex, history of hypertension and history of diabetes did not influence the chance of having any test, but older age strongly reduced the chances of receiving extensive evaluation. When CT scanning was available, the utilization of a CT as well as other diagnostic studies including cerebral angiography, radionuclide brain scan, EEG and EKG was increased. The odds of receiving a CT scan increased if the patient was married, and decreased with a history of previous stroke. A history of previous TIA increased the chance of having a cerebral angiogram while a history of cardiac disease decreased the chance. There were striking regional geographic differences in the use of CT, radionuclide brain scanning and cerebral angiography which may, in part, reflect differences between the availability of these technologies in urban and rural hospitals. These results indicate that evaluation of stroke patients remains heterogenous.

Brain death: confirmation by radionuclide cerebral angiography.

Dynamic radionuclide cerebral angiography was performed in 14 patients with suspected brain death. In 10 of 14 patients, no intracranial arterial perfusion was demonstrable, thus confirming brain death. In four patients, faint venous activity was seen in the sagittal sinus only. All these patients also eventually died. Radionuclide cerebral angiography provides a simple and noninvasive means to confirm brain death in critically ill patients maintained on life support systems particularly when an electroencephalogram and four vessel contrast angiography may be either impractical or equivocal.

Evaluation of regional cerebral circulation based on absolute mean transit times in radionuclide cerebral angiography

In radionuclide cerebral angiography (RCA) the analysis of the activity-time curves recorded over the hemispheres following an intravenous bolus injection of a radioactive indicator permits the evaluation of absolute cerebral mean transit times (MTTcb). The inverse of MTTcb is an index of cerebral blood flow. The bolus parts of the cerebral activity curves were fitted with gamma-variate functions. The duration of the injection bolus and its subsequent dispersion through the cardiopulmonary circulation were corrected for using the activity curve over the aortic arch. The RCA is non-invasive, rapid, easy to perform and without risk for the patient. The RCA is recommended for quantitative evaluation of major alterations in cerebral perfusion.

Brain death in children: Characteristics common carotid arterial velocity patterns measured with pulsed Doppler ultrasound

The clinical criteria for brain death in children remain controversial. An accepted confirmatory test for brain death is the documented absence of intracranial blood flow, the most common methods being arteriography and radionuclide cerebral angiography. We correlated the common carotid arterial blood velocity patterns measured by pulsed Doppler ultrasound in 32 brain-dead infants and children with results of their clinical examinations and, whenever possible, with radionuclide cerebral angiography. A distinct, characteristic carotid arterial blood velocity waveform indicating absent cerebral blood flow appeared in 19 of the 23 brain-dead patients 4 months of age or older. The velocity patterns of the other four older children were similar, but not identical, to the characteristic waveform. The remaining nine brain-dead patients were infants 4 months of age or younger. These infants had velocity waveforms different from those of healthy infants, but also were totally different from the characteristic brain death pattern of older children. No patient had the characteristic brain death waveform without being clinically brain dead. Measurement of carotid arterial blood velocity with pulsed Doppler ultrasound is a repeatable, noninvasive, portable test useful for confirmation of brain death in children.

Evaluation of asymmetries of blood flow rate and of circulation time by intravenous radionuclide cerebral angiography in patients with ischemic completed stroke.

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.

Radionuclide cerebral angiography and the timing of aneurysm surgery

Radionuclide cerebral angiography and the timing of aneurysm surgery

Radionuclide cerebral angiography and the timing of aneurysm surgery.

Forty-five patients with subarachnoid hemorrhage due to verified intracranial aneurysms were studied prospectively to determine whether delaying operations in those patients with abnormal cerebral perfusion, assessed by radionuclide dynamic scanning, would lower case management mortality. Twenty-nine patients had intracranial operations when their radionuclide dynamic scans demonstrated normal perfusion. The one death in this group occurred in a patient who suffered a massive hemorrhage during operation as the bone flap was elevated. There were no instances of delayed spasm after operation. Of the 16 remaining patients who were treated without operation, 5 died. Only 1 of these deaths resulted from recurrent hemorrhage. This patient had normal cerebral perfusion but was not operated upon because of severe associated medical problems. Cerebral infarction occurred in 10 of the 16 unoperated patients, all of whom had persistently decreased cerebral perfusion. Four of these patients died of their infarctions or related causes. Although a trend related vessel caliber as seen on arteriograms and perfusion delay seen on dynamic scanning, individual exceptions were numerous. This study shows that radionuclide scanning, a safe procedure, is useful for identifying two types of patients: those with normal perfusion prone to rebleeding in whom an early operation is safe and those in whom perfusion is decreased. The latter group is prone to cerebral infarction, but rebleeding from the aneurysm is unlikely. Operation should be delayed in these patients until cerebral perfusion returns to normal or for several weeks if cerebral perfusion remains diminished.

Alterations in cerebrospinal fluid flow dynamics in cerebrovascular occlusive disease demonstrated by radionuclide cisternography.

Sixteen patients with cerebrovascular occlusive disease were studied with radionuclide cisternography, brain gamma camera imaging, and radionuclide cerebral angiography. Alterations in cerebrospinal fluid flow dynamics were seen in 9 patients. Considerable further investigation is needed to establish a better understanding of cerebrovascular occlusive disease and the role of the alterations of cerebrospinal fluid dynamics in the natural history of the disease.