Evaluation of cerebral vascular disease with radionuclide angiography

Conventional radionuclide brain imaging in the era of transmission and emission tomography

The clinical applications for conventional radionuclide brain imaging have declined considerably since the introduction of newer imaging modalities (computerized cranial tomography [CCT], nuclear magnetic resonance [NMR]). Currently, conventional brain imaging primarily serves as a complementary test when CCT is negative or equivocal and strong clinical suspicion remains. Selected areas in which radionuclide imaging may be the preferred modality include evaluation of cerebral perfusion in assessment of brain death, detection of early viral encephalitis, evaluation of major venous sinus patency, external marking for localization of intracranial tumor, and in selected cases of suspected subdural hematoma, brain tumor, and cerebrovascular disease. The concept of conventional radionuclide brain imaging will likely undergo considerable change in the near future as newer radiopharmaceuticals are introduced and wider application is made of single photon emission computerized tomography (SPECT) and positron emission tomography (PET) imaging.

Management of patients with established ("completed") cerebral infarction

Management of patients with sudden neurological deficit must be based on complete knowledge of the underlying cause. In about 80% of such patients, a careful history and examination will lead to a precise etiologic and anatomic diagnosis. If the deficit is vascular in etiology, therapy and prognosis depend on its stage of evolution.

Radionuclide brain imaging--its role and relation to CT scanning

Separate CNS disease entities are discussed with either the complementary or exclusive indications for radionuclide brain imaging and computerized cranial tomography. Either modality alone has a potential overall precision somewhat in excess of 90% in the localization of cerebral lesions with the effectiveness of each modality differing according to the histology and anatomic location of the lesion. Most investigators agree that the combined application of the two procedures is far superior to their separate use. Routine dynamic isotope studies are essential and in addition, new radiopharmaceuticals and technological advances may improve the radionuclide evaluation of CNS disease. Areas discussed include: primary and secondary CNS neoplasms; acute cerebrovascular accidents; arteriovenous malformations; traumatic cerebrovascular disease; hydrocephalus and dementia; and intracranial inflammatory processes.

The complementary role of computerized axial transmission tomography and radionuclide imaging of the brain

Computerized axial transmission tomography and radionuclide imaging are complementary procedures, and the following recommendations are made as to their use. Where there is no real clinical suspicion of intracranial disease, either modality can be used for "rule out" screening; the choice can frequently be made on the basis of which modality is cheaper or more quickly available. It should be remembered that "quicker" is often "cheaper". Total cost is determined, not only by the cost of the procedure, but also the per diem costs incurred in waiting for that procedure. Thus the more expensive modality may, in effect, be cheaper if delays are shorter. Screening of the elderly patient, particularly when atrophy or communicating hydrocephalus is of clinical concern, should be by the CT method because of its ability to visualize cerebrospinal fluid spaces. When clinical signs and symptoms point to intracranial abnormality, both modalities should be utilized. If either study done first is normal, use of the other modality is mandatory. When the first study is positive with pathognomonic findings for a specific disease, which totally explains the patient's neurologic problems, the second study need not be employed. Such examples might include the fresh cerebral hemorrhage demonstrated by CT imaging, the AV malformation defined by dynamic-static radionuclide imaging, or multifocal metastatic lesions defined by either. However, when the clinical picture is not totally and satisfactorily explained by the demonstrated disease, the other modality should also be employed. Under many circumstances, neither study will be so reliable, specific, and free of false-negative or false-positive findings as to warrant ignoring the additional information potentially available from the other study.

Radionuclide cerebral blood flow and carotid angiogram. Correlation in internal carotid artery disease

Radionuclide cerebral blood flow (CBF) examinations of 48 patients with atherosclerosis, 18 with occlusion and 30 with stenosis of the internal carotid artery (ICA) were correlated with their respective cerebral angiograms. The following results were obtained. Flow was visually unilaterally diminished in 29 (60%) of 48 patients, including 14 (78%) with occlusion and 15 (50%) with stenosis. Sixty-two percent of the subjects with severe stenoses and 46% of the patients with mild stenoses had a positive flow study. Diminished flow was evident in the neck in 80% of the patients, intracranially in 20%. Positive radionuclide angiograms always pointed to the side with occlusion or the greater degree of stenosis even though bilateral interanl carotid disease was frequently found (54%). The data leading to the differentiation between major and minor ICA stenosis are not sufficient to justify any conclusion.

Radionuclide angiography

Radionuclide angiography is an established, widely used diagnostic tool. It is safe, easy to perform, and the low patient radiation dose makes frequent follow-up studies feasible. High-quality scintiscans have contributed to the widespread clinical acceptance of the procedure. The areas of application include virtually every organ of the body. In the brain, abnormalities in cerebral perfusion may be detected with this technique. Hepatic and renal tumors can be differentiated from cysts with radionuclide angiography. Its application to cardiology is achieving rapid growth and acceptance in both congenital and acquired heart disease.

Cerebral dynamic studies for early detection of recurrent anaplastic intracranial gliomas

The authors compared radionuclide cerebral dynamic studies, brain scans, and clinical evaluation as indicators of recurrence of intracranial anaplastic gliomas and found cerebral dynamic studies more sensitive to tumor growth than static brain scans. The former may show changes prior to clinical evidence of tumor progression.