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.     

Clinical application of 18F-FDG-PET in patients with brain death]

In order to evaluate glucose metabolism in brain death, 18F-FDG-PET scans were performed in three patients with clinically highly suspected brain death. One case was caused by head trauma and other two cases were by subarachnoid hemorrhage. All of them were in deep coma without spontaneous breathing, whose intracranial pressure was remarkably elevated up to the level of mean arterial pressure. Nineteen frames of dynamic scan were started soon after intravenous injection of 18F-FDG for one minute per frame, followed by 10 minutes of static scan which started 40 minutes after the injection. Both in dynamic and static scan, no significant intracranial accumulation of 18F-FDG was seen in all of three cases. This finding can be interpreted as the evidence that there is no significant glucose utilization from blood in the brain. This is the first report of clinical application of 18F-FDG-PET to brain death. Our results support the clinical diagnosis of brain death and 18F-FDG-PET can be of value for the assessment of glucose metabolism in patients with suspected brain death.     

Clinical use of technetium-99m HM-PAO for determination of brain death

We report our clinical experience with the use of [99mTc]hexamethyl propyleneamine oxime (HM-PAO) in establishing a diagnosis of brain death in 11 patients following trauma to the head and four patients who suffered atraumatic injuries. In 9/15 studies there was no intracranial flow present and brain death was then confirmed by standard criteria. Of the remaining 6/15 studies which showed evidence of cerebral perfusion, 3/6 patients underwent a subsequent HM-PAO study which showed cessation of perfusion. One additional patient died of pneumonia and two patients survived. Thus, in all cases where there was no flow present the diagnosis of brain death was later confirmed whereas three patients clinically thought to be brain dead showed significant perfusion and survived the cerebral trauma. HM-PAO may be useful in determination of brain death because it provides unequivocal results, can be performed by planar imaging at the bedside, and does not require withdrawal of medical therapy, thus allowing a diagnosis to be established more rapidly.     

Intravenous angiography in brain death: report of 140 patients

We present our experience and discuss the value of cerebral intravenous digital subtraction angiography (IV DSA) in the diagnosis of brain death. A total of 140 patients presenting with clinical signs of brain death were studied by IV DSA. According to the angiographic appearance of the vertebrobasilar system, the patients were divided into four groups. Cessation of blood flow within the internal carotid arteries and their branches was consistently found. Attention is focused on 9 patients with persistent blood flow within the posterior fossa. In sedated patients in whom EEG and evoked brain-stem responses are non-diagnostic, or in order to shorten the observation time, transcranial Doppler should be performed to determine the appropriate moment for IV DSA, which is a reliable method of confirming brain death. Received: 14 February 1996 Accepted: 15 July 1996     

MR 'hot nose sign' and 'intravascular enhancement sign' in brain death.

Three cases of MR with gadopentetate dimeglumine in patients diagnosed with cerebral death are presented. Observation of an MR "hot nose sign" and an "intravascular enhancement sign" provided additional imaging support in the clinical diagnosis of brain death. The MR findings in brain death include: 1) transtentorial and foramen magnum herniation, 2) absent intracranial vascular flow void, 3) poor gray matter/white matter differentiation, 4) no intracranial contrast enhancement, 5) carotid artery enhancement (intravascular enhancement sign), and 6) prominent nasal and scalp enhancement (MR hot nose sign). Additional modalities for confirming brain death are discussed.     

Variant flow patterns in radionuclide cerebral imaging performed for brain death

Radionuclide cerebral imaging (RCI) is a commonly used technique for detection of intracranial blood flow in patients with clinically suspected brain death. In 115 studies performed on 95 patients in a six-year period at the Geisinger Medical Center, a number of variant flow patterns have been observed. Although all have been described previously, there has been no review of these patterns on studies performed for brain death. The significance of normal blood flow, absent blood flow, isolated superior sagittal sinus activity, luxury perfusion, hypoperfusion, hemiperfusion, and jugular venous reflux is discussed. Any demonstrable intracranial blood pool activity is presently considered to counter a diagnosis of brain death, except that jugular reflux renders an examination uninterpretable. Technique must be top quality but, even so, RCI cannot evaluate basilar brain flow. Nonetheless, RCI is a valuable adjunct in helping to establish the clinical diagnosis of brain death.     

99mTc HM-PAO brain perfusion SPECT in brain death

Diagnosis of brain death must be certain to allow discontinuation of artificial ventilation and organ transplantation. Brain death is present when all functions of the brain stem have irreversibly ceased. Clinical and electrophysiological criteria may be misinterpreted due to drug intoxication, hypothermia or technical artefacts. Thus, if clinical assessment is suboptimal, reliable early confirmatory tests may be required for demonstrating absence of intracranial blood flow. We have easily carried out and interpreted^99mTc HM-PAO SPECT in a consecutive series of 40 comatose patients with brain damage, without discontinuing therapy. Brain death was diagnosed in 7 patients, by recognising absence of brain perfusion, as shown by no intracranial radionuclide uptake. In patients in whom perfusion was seen on brain scans, HM-PAO SPECT improved assessment of the extent of injury, which in general was larger than suggested by CT.     

Radionuclide studies in the determination of brain death: criteria, concepts, and controversies

Forty years after the publication of a landmark paper by the Ad Hoc Committee of the Harvard Medical School, the general concept of brain death has achieved widespread acceptance. In the United States, irreversible dysfunction of the brain and brainstem are required for the diagnosis of brain death. Although primarily based on clinical evaluation, confirmatory examinations, including radionuclide blood flow studies, play an important role in augmenting the physical examination in special situations when some of its specific components cannot be performed or reliably evaluated. The 2 main radionuclidic techniques used in evaluation of brain death are radionuclide angiography with nonlipophilic radiopharmaceuticals and parenchymal imaging with lipophilic agents. Specific technical guidelines for determination of brain death have been promulgated by professional medical societies. In the vast majority of cases, blood flow examinations are useful in confirming brain death. Nonetheless, on occasion patients clinically diagnosed with brain death will exhibit persistent intracranial blood flow or electrical activity. Existence of these contradictory cases reveals underlying inconsistencies in the definitions of brain death. We hypothesize that the existence of these apparent contradictions is related to differences in sensitivity of the physical examination and the confirmatory examinations, differences in localization of the physical examination and confirmatory tests, and differences between blood flow and cerebral function as markers of brain death.     

Misdiagnoses of 11C-choline combined with 18F-FDG PET imaging in brain tumours

BACKGROUND AND OBJECTIVE: The widely applied F-FDG is known for its disadvantage in brain tumour PET imaging because of its high background uptake. C-choline can achieve high contrast of brain tumour imaging and was expected to have higher sensitivity and specificity. We analysed the misdiagnoses in C-choline PET imaging in brain tumours with the aim of improving the accuracy of diagnosis with C-choline PET imaging. PATIENTS AND METHODS: We selected 10 patients proven to have been misdiagnosed on the basis of histopathological correlation and clinical follow-up among 94 patients (110 studies) who underwent C-choline PET/CT for diagnosed or suspected brain tumour between 23 March 2005 and 8 February 2007. C-choline PET imaging were performed on a Biograph Sensation 16 PET/CT scanner (Siemens Medical Systems), F-FDG imaging was also performed as reference. RESULTS: Of all 10 misdiagnosed patients, five were false positive (one abscess, one tuberculosis, one benign gliocyte proliferation, one inflammatory granuloma and one demyelination), four were false negative (two metastases from lung cancer, one lymphoma, one grade II glioma) and one was misdiagnosed by wrong interpretation due to lack of experience. The rate of false positives was (5/110) 4.55%; the rate of false negatives was (4/110) 3.64%; the accuracy of C-choline alone was (93/110) 84.5%; by comparison, the accuracy of F-FDG alone was (78/110) 70.9%. CONCLUSIONS: C-choline imaging has a certain rate of false positivity and false negativity. With proper application, C-choline might have greater potential than F-FDG for brain tumour PET imaging.     

A case of generalized hypoxic brain damage following traumatic brain damage

In forensic autopsy cases, transient brain hypoxia can be induced by cardiac arrest, hypovolemic shock, and other conditions with severe circulatory failure. Although cortical laminar necrosis in watershed areas between territories of the major cerebral arteries is occasionally seen, cases with global hypoxic damage to the brain is rare, because patients with irreversible severe brain damage rarely survive for more than a few days. In this report we describe autopsy results for an injury victim who survived unconscious for approximately 4 weeks after admission. Macroscopic thinning of the gray matter and uniformly cheesecake-like cloudy changes in white matter were observed. Microscopically, cortical laminar necrosis was observed in all lobes of the cerebrum, and massive gliosis was diffused throughout the white matter. We speculate that traumatic brain damage, continuous hypoxemia, and many other factors induced these characteristic pathological changes during the long time interval from brain damage to death.     

Longitudinal CT study of parenchymal brain changes in glioma survivors

We reviewed the serial CT studies obtained between 1974 and 1986 of 31 patients with malignant glioma who survived for 2 to 11 years after surgical removal of their tumors. In all cases surgery was followed by radiation therapy to the head (6000 rad) and chemotherapy. Patients were divided into two age groups: those under age 40 (n = 13) and those over age 40 (n = 18). By 2 years all patients in the older group developed evidence of leukoencephalopathy characterized by periventricular zones of decreased attenuation. Only 58% of the younger group showed evidence of white matter changes at this point. All patients from both age groups who survived for 4 years developed leukoencephalopathy. The severity of leukoencephalopathy from 6 months after surgery and beyond was always greater in the older group. All patients developed cerebral atrophy as evidenced by sulcal dilatation and ventricular enlargement. Atrophy was progressive beginning with the first postirradiation scan, and was always more severe in the older patients. A significant difference was found in the clinical status of the two age groups as determined by the mental status score and the Karnofsky scale. Despite progressive brain changes, survivors under age 40 maintained a nearly normal mental status and Karnofsky scores until their death, whereas survivors over age 40 showed progressive clinical decline.     

Changes of the cerebral mannitol concentrations in the course of brain death of a rodent model

Determining the time of brain death is one of the critical issues in forensic examinations. Few authors have attempted to determine the time of brain death using pharmacokinetic approaches. We investigated cerebral concentrations of mannitol of which a single dose (1 g/kg) was administered in the course of brain death. The inflation of an epidural balloon was adopted as a rodent model of brain death. Brain death was determined using ordinary tests. Specimens were collected 4 h after brain death. Brain water content was higher in brain dead (BD) groups than those in control groups. Cerebral concentrations of mannitol in the BD group were significantly higher than those in the control group (P<0.01). In all areas of brain the concentration was the highest at the time when mannitol was administered during balloon inflation. Interhemispheric difference in the cerebrum was observed, followed by balloon inflation (P<0.05). Significant differences were observed in the average concentration of administered mannitol before and after brain death in the contralateral hemisphere (P<0.01) and in the brainstem (P<0.01). As the concentrations of mannitol in the brain are affected by cerebral trauma and brain death follows, mannitol can be used to determine the time of brain death at forensic examinations.     

Perfusion "Brain Death" Scintigraphy in Traumatic and Hypoxic Cerebral Insults: Correlation With CT

ABSTRACT: In the United States, approximately 1.7 million patients are treated annually for traumatic brain injury, and cerebrovascular insults are the third leading cause of death. Although CT plays a central role in the initial assessment of suspected intracranial injury, planar brain scintigraphy provides valuable information regarding cerebral perfusion, function, and brain death. An understanding of the complexity of injuries is helpful in scintigraphic image interpretation. To illustrate potential scintigraphic confounders, we present 8 suspected brain death cases with correlative CT. Even with negative brain death studies, severe brain injury by CT portends grave outcomes.     

Reassessment of quantitative thallium-201 brain SPECT for miscellaneous brain tumors

In order to reassess the value of quantitative thallium-201 brain SPECT in the differentiation of miscellaneous brain tumors, we studied a total of 89 patients—35 pre-operative patients suspected of having a brain tumor and 54 post-operative patients with a brain tumor. We came to the conclusion that quantitative Tl-201 brain SPECT was very useful in discriminating cerebral radiation necrosis from recurrent tumor, estimating residual tumor burden, and detecting tumor regrowth earlier in postoperative patients. In preoperative patients, however, Tl-201 SPECT cannot be used effectively to differentiate glioma from other intracranial tumors, although intense uptake of Tl-201 may provide evidence of glioblastoma or a hypervascular lesion.     

重型颅脑损伤的临床观察与护理

目的探讨重型颅脑损伤患者的临床观察与护理措施。方法对我院救治128例重型颅脑损伤患者进行严密的早期病情监护观察,术后预防并发症护理、康复期护理及出院健康指导。结果 128例重型颅脑损伤患者结果良好86例,中残12例,重残8例,植物生存1例,死亡21例;抢救成功率为83.6%。结论及时准确而有预见性、针对性、目的性的观察护理,正确的康复锻炼及健康指导,对减少并发症、降低死亡率及改善伤者的预后有积极的意义。     

MR imaging of brain stem gliomas

Magnetic resonance (MR) and CT examinations of 26 patients with the established or clinically suspected diagnosis of brain stem glioma were reviewed. Eleven tumors were seen on both MR and CT. The entire extent of the abnormality was better outlined on MR, although CT was more advantageous in demonstrating cystic components and calcium deposition. Magnetic resonance and CT depicted focal intratumoral hemorrhage equally. Magnetic resonance was found to be particularly suitable to follow up the progression or regression of the disease. Of particular interest were two patients with evidence of aqueductal obstruction but normal CT appearance of the midbrain; the causative abnormality, believed to be a glioma, was clearly shown by MR imaging. In nine patients the normal appearance was helpful to exclude the possibility of a brain stem glioma. Thus far, results have shown 100% sensitivity (true positive ratio) and specificity (true negative ratio) with MR in the evaluation of brain stem gliomas. It is concluded that MR imaging should be the examination of choice and could be the definitive screening procedure in patients with suspected brain stem glioma.     

Results of radiation therapy in brain metastases with reference to computerized tomography

Between 1979 and 1985, 193 patients were submitted to radiotherapy of the brain for formation of metastases. A primary irradiation was performed in 159 patients, 34 patients had been treated by surgery. The median survival time after diagnosis of all irradiated patients (40 to 60 Gy within four to six weeks) was 4.9 months, 22% of the patients survived one year. Patients with mammary carcinomas and patients with bronchial carcinomas showed marked differences in median survival times (4.2 and 6.9 months, respectively) and one-year survival rate (11% and 32%, respectively). In histologic examination, the extent of extracerebral formation of metastases was the decisive parameter for survival. At the end of radiotherapy, 47% of patients showed an amelioration in neurologic deficiency, 16% deteriorated. A follow-up by computed tomography with observation periods between four and 34 months was possible in 84 patients. Most of these patients showed improvement in computed tomography during a period of four to twenty weeks after the beginning of radiotherapy. Later on, about two thirds of the controlled patients had again deterioration with local progression or new formation of metastases in spite of total brain irradiation. A long-term normalization (greater than one year) was observed only in patients with mammary carcinomas.     

Imaging strategies for MR of the brain

MR has emerged as the imaging modality of choice for the brain in patients presenting with seizures, chronic headaches, progressive neurologic deficits, ataxia, vertigo, hearing loss, visual loss, congenital abnormalities, signs of increased intracranial pressure, dementia, suspected multiple sclerosis, and in the vast majority of other elective neurologic problems. CT should currently be considered the primary imaging modality in patients with acute neurologic deficits (stroke), acute onset of severe headaches, and when fine bone detail is required. Acutely injured patients are more readily studied with CT. The vast majority of patients in whom CT is preferred are seen in emergent situations, frequently in hospital emergency rooms. The effects of trauma beyond the acute stage are best evaluated with MR. In the future, MR is likely to become the procedure of choice in even more clinical situations than at present. A summary of currently recommended primary imaging modalities in various clinical situations is provided in Table 1.     

The role of xenon CT measurements of cerebral blood flow in the clinical determination of brain death

The demonstration of absent blood flow to the brain is often used as a confirmatory test of brain death. Traditionally, cerebral angiography and dynamic radionuclide brain scanning have been used for this purpose. Recently, xenon CT cerebral blood flow techniques have been developed and applied to a wide variety of clinical problems, including the confirmation of brain death. We report our experience with xenon CT studies performed over a 7-year period (1983-1989) in 30 patients with brain injuries. These patients met clinical criteria for brain death within 24 hr of the study. Twenty patients had average global flow values of less than 5 ml/100 ml/min. Seven patients demonstrated mixed flow patterns, whereby large areas of brain showed flow values of less than 5 ml/100 ml/min and residual pockets of flow greater than 5 ml/100/ml/min. Globally symmetric normal to hyperemic flows were seen in three patients. Our study suggests that the demonstration of average global flows of less than 5/ml/100 ml/min is confirmatory of brain death. Demonstration of persistent flow to the entire brain or regions of the brain is not diagnostic of brain death but also does not exclude such an outcome in patients with severe brain injuries. Xenon-derived flow information may be clinically useful in determining the patient's prognosis and in counseling the patient's family.     

Thallium-201 accumulation in a patient with brain abscess

A 57-year-old man was admitted to our hospital because of high fever and generalized tonic seizure. Brain magnetic resonance imaging (MRI) delineated multiple abnormal intensity areas. Thallium-201 (201Tl) scintigraphy revealed abnormal uptake in the brain. The imaging findings did not allow definitive exclusion of brain tumor, even though brain abscess was the more strongly suspected diagnosis. As the patient improved, the multiple abnormal intensity areas in the brain on MRI and the abnormal areas of accumulation on 201Tl scintigraphy were reduced, and eventually completely disappeared. A final diagnosis of brain abscess was therefore made. Since relatively few studies have reported 201Tl accumulation in cases of brain abscess, we report here our patient in whom the changes in the accumulation of 201Tl in a brain abscess were observed over time.