Philip Braunstein

Brain death: II. Neuropathological correlation with the radioisotopic bolus technique for evaluation of critical deficit of cerebral blood flow

An innocuous intravenous portable radioisotopic test using technetium 99m pertechnetate was employed to demonstrate the deficit of cerebral blood flow associated with brain death. The results are compared to those of bilateral carotid and vertebral angiography in 20 patients. Absence of a bolus tracing from the head in the presence of a control tracing of a bolus from the femoral artery in two successive studies one hour apart reliably correlated with the clinical and electroencephalographic findings signifying cerebal death in comatose, apneic patients. Angiography indicated absence of intracranial circulation in 10 patients. Stasis filling or retrograde emptying of arterial vessels (or both) occurred in 7 patients. There was no evidence of venous filling in any of these 17 patients; all of them had either an absent head bolus or an “intermediate tracing.” Results indicate that either form of tracing represents a critical decrease of cerebral blood flow. Two other patients had evidence of severely impaired abnormal posterior fossa circulation without angiographic evidence of cerebral circulation; both of these patients had an absent head bolus. An additional patient had an unusually small head bolus, and angiography revealed extravasation of radiopaque material but no evidence of intracranial circulation. We conclude that the bolus technique is a helpful adjunct in diagnosing brain death.

ANGIOGRAPHIC FINDINGS IN BRAIN DEATH

With advances in medical techniques, “life” may be supported even though irreversible brain t damage has occurred. To avoid prolonged efforts to maintain a brain-dead patient until systemic death occurs and to conserve organs for transplantations, it is necessary to rely on a diagnostic test that would aid in conclusively determining the irreversibility and scope of the cerebral insult. Although isotopic determination of a cerebral blood-flow deficit is a rapid and reliable diagnostic adjunct to determine cerebral t death,3-sv l6, l7 there are times that in the clinical judgment of the examining neurologist, angiography is required before it can be stated with certainty that brain death has occurred. Angiography may thus be necessary when the isotopic bolus study demonstrates an “intermediate” or small bolus pattern or is technically unsatisfactory, or when the EEG is not unequivocally isoelectric. Furthermore because of technical considerations the bolus technique is primarily limited to use in adults.15 Therefore intracranial angiography may be necessary to document brain death in infants and small children. Many European authors maintain that the sine qua non of brain death rests with the demonstration of absence of intracranial circulation by angiography.?. s~ 2 3 Though serving a limited role in the diagnosis of brain death, the findings at angiography are recorded so that when this diagnostic test is used as the final confirmation of the determination of death, no confusion will result. It is our belief that when the advocates of angiography become familiar with the results obtained by the bolus technique, they will rarely resort to angiography.

Production of 167Tm for medical use

A method is described for producing sufficient amounts of 167Tm for medical use in a carrier free form on a small medical cyclotron. Using enriched 167Er2O3 up to 75 μCi/μAhr can be produced. The biological distribution of 167Tm HEDTA in rabbits is also presented. Most of the activity (up to 70 per cent) is localized in the skeleton and the rest is excreted.

Evaluation of the critical deficit of cerebral circulation using radioactive tracers (bolus technique).

Technological and medical advances now often make it possible to sustain life in deeply comatose patients who would previously have died. These same advances at times also make possible prolongation of life in a body when the brain of that individual has died. In as far as the brain is the essence and substance of individual human existence, the undue prolongation of life in a body with a dead brain is futile. Such efforts prolong the anguish of relatives and drain resources which could be used for individuals still able to benefit from them. The advent of transplant surgery has created a need for viable organs; these tend to deteriorate after cessation of the heartbeat. Therefore, individuals with brain death are a source of such organs if they can be removed before the heart stops. The above factors may result in a situation that requires a relatively rapid decision regarding the question of brain death. It should be clearly borne in mind that under certain circumstances, comatose states, including those that are reversible, may temporarily mimic brain death in all clinical and electroencephalographic Situations that may transiently simulate brain death may occur in patients with drug intoxication, but have also been reported in other conditions, such as induced hypothermia, encephalitis, and metabolic disorders. The Harvard criteria’ require 24 hours of observation plus the absence of drugs and hypothermia in order to make a judgment of brain death. The problem of drug intoxication is often a difficult one to deal with since there may be no detailed history available in such patients. Moreover, the laboratory search for drugs is not rapid, especially when the nature of the drug is not known.\ It is particularly noteworthy that a collaborative study on cerebral survival (CSCS),9x lo based on the study of 503 comatose and apneic patients, found a significant proportion of these patients had drug levels in the blood compatible with coma, even when other more obvious causes of coma were known.El 1

Radionuclide Uptake Studies of Bone: A Quantitative Method of Evaluating the Response of Patients with Paget's Disease to Diphosphonate Therapy

In order to evaluate and quantitate the therapeutic efficacy of disodium etridonate (EHDP) in the treatment of Pagets disease, a prospective double-blind study was instituted. Subjects received either placebo, low-dose EHDP, or high-dose EHDP and were evaluated prior to therapy and 6 months later. Bone scans were performed with 99mTc or 18F and radioisotopic uptake studies were conducted. The results were correlated with clinical improvement, biochemical parameters, and radiographic skeletal surveys, and indicate that the radioisotopic uptake studies are both a sensitive and reproducible means of evaluating the degree of response to EHDP.

Augmented Splenic Uptake of 99mTc-Sulfur Colloid in Patients with Malignant Melanoma

Liver scans of 63 consecutive patients with malignant melanoma were reviewed for augmented splenic uptake of 99mTc-sulfur colloid in the absence of hepatic abnormality, e.g., (a) focal lesion(s) or liver enlargement on the scan, (b) clinical indications of liver abnormality at or since the time of examination, or (c) abnormal liver chemistries. Of 22 such patients with malignant melanoma, 10 showed augmented splenic radioactivity. 60 patients with carcinoma of various sites and no suspicion of liver involvement were used as controls. Augmented splenic activity associated with malignant melanoma should be considered when interpreting liver scans.

The uses and limitations of radiosotopes in the investigation of gastrointestinal diseases

Advances in the physical and biological sciences have in recent years led to a rapidly increasing use of radioactive agents in clinical medicine. The distinctive properties of these agents have made them invaluable for a large variety of uniquein vivo andin vitro diagnostic tests. In order to help the clinician employ such tests productively and realistically, we have attempted to review the present status of radioisotopes with regard to gastrointestinal diseases. Emphasis has been placed not only on their value but also on their limitations; the degree of safety forin vivo application has also been briefly considered.Advances in the physical and biological sciences have in recent years led to a rapidly increasing use of radioactive agents in clinical medicine. The distinctive properties of these agents have made them invaluable for a large variety of uniquein vivo andin vitro diagnostic tests. In order to help the clinician employ such tests productively and realistically, we have attempted to review the present status of radioisotopes with regard to gastrointestinal diseases. Emphasis has been placed not only on their value but also on their limitations; the degree of safety forin vivo application has also been briefly considered.

Bone Scanning in Metastatic Calcification to the Lungs

A case of pulmonary metastatic calcification demonstrated by bone scanning is presented. It appears that the sensitivity of bone scanning in the detection of these calcific deposits depends upon the nature of their crystalline structure. The nature of these calcific deposits and their relationship to bone scanning is discussed.

Posterior Fossa: A Clinical Comparison of Radionuclide Scanning and Computed Tomography

&NA; CT and RN imaging both appear to be less sensitive in detecting lesions in the posterior fossa than in the supratentorial area. This study compares the accuracy of these two modalities in 27 patients with a variety of proven posterior‐fossa lesions, all studied by both methods. The overall yield of RN studies in these cases was 59%. The yield of CT without contrast was 67%. The combination of RN and noncontrast CT detected 85% of the cases. The combination of CT with and without contrast had, at best, the same accuracy. When used as a screening test, the small but established risk of IV contrast material must be considered. CT, both with and without contrast, plus RN still missed two out of 27 cases.

The role of gallium and bone scintigraphy in disseminated coccidioidomycosis.

The osseous lesions of disseminated coccidioidomycosis may be detected by bone but not by gallium scintigraphy or vice versa. This case emphasizes the need for performing both bone and gallium scans to avoid missing potentially serious bone lesions.