technetium-tc-99m-exametazime and Hyperemia

Hypoperfusion on single-photon emission computed tomography (SPECT) of the stroke-like lesion (SLL) at the hyperacute stage of mitochondrial encephalopathy with lactic acidosis and stroke-like episodes (MELAS) is considered to be a supportive evidence of the mitochondrial angiopathy theory. Our objectives were to examine whether other neuroimages, especially transcranial color-coded sonography (TCCS), done at the hyperacute stage of stroke-like episode (SLE) is consistent with hypoperfusion of the SLL. We reviewed the magnetic resonance imaging (MRI), SPECT, cerebral angiography, and TCCS of a patient with MELAS syndrome, all of which were performed at the hyperacute stage of one SLE. MRI on the 1st day post SLE showed right temporoparietal lesion with vasogenic edema. SPECT on the 2nd day showed focal decreased uptake of technetium-99m hexamethylpropyleneamine oxime ((99m)Tc-HMPAO) in the same region, but cerebral angiography and TCCS on the 3rd day showed increased regional cerebral blood flow (rCBF) and distal arteriole dilation in the same region. TCCS can delineate increased rCBF of the SLL at the hyperacute stage of SLE. We propose that the discrepancy between the decreased (99m)Tc-HMPAO uptake and increased rCBF might be caused by mitochondrial dysfunction. The phenomenon of "hypoperfusion" on SPECT might be caused by cell dysfunction but not decreased rCBF. We suggest that SPECT can be complemented by angiography and TCCS in future studies to delineate the perfusion status of SLLs.

Topics: Adult; Brain Edema; Cerebral Angiography; Cerebrovascular Circulation; Humans; Hyperemia; Image Processing, Computer-Assisted; Magnetic Resonance Imaging; Male; MELAS Syndrome; Middle Cerebral Artery; Perfusion; Radiopharmaceuticals; Stroke; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed; Ultrasonography, Doppler, Transcranial

A 60-year-old woman presented with a rare case of hyperperfusion syndrome after stent placement for subclavian artery stenosis manifesting as dizziness due to vertebrobasilar insufficiency. Three days after undergoing stent placement to treat the severely stenotic (90%) right subclavian artery, she suffered intracranial hemorrhage related to hyperperfusion syndrome. Preoperative single-photon emission computed tomography findings of low cerebral perfusion and poor perfusion reserve might indicate the possibility of hyperperfusion syndrome after stenting in patients with subclavian artery stenosis.

Topics: Cerebral Angiography; Female; Humans; Hyperemia; Intracranial Hemorrhages; Magnetic Resonance Angiography; Middle Aged; Risk Factors; Stents; Subclavian Steal Syndrome; Syndrome; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed; Vertebrobasilar Insufficiency

We used Technetium-99m hexamethyl propylene amine oxime single-photon emission computed tomography (HMPAO-SPECT) and magnetic resonance imaging (MRI) to evaluate a 30-year-old woman who developed cerebellar dysfunction after infection with Epstein Barr virus. Although no abnormal findings were evident from a brain MRI, the HMPAO-SPECT revealed increased perfusion in both cerebellar hemispheres. The patient improved without specific treatment. Two sequential HMPAO-SPECTs showed gradually reduced hyperperfusion in the cerebellum, which was correlated with her clinical recovery. We suggest that brain HMPAO-SPECT may thus be useful for identifying acute cerebellitis and predicting its clinical outcome.

Topics: Adult; Cerebellar Diseases; Cerebellum; Cerebral Cortex; Dominance, Cerebral; Encephalitis, Viral; Epstein-Barr Virus Infections; Female; Follow-Up Studies; Gait Ataxia; Humans; Hyperemia; Image Enhancement; Image Processing, Computer-Assisted; Neurologic Examination; Regional Blood Flow; Remission, Spontaneous; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Periodic lateralised epileptiform discharges (PLEDs) can be seen associated to nonconvulsive status epilepticus (NCSE), although their pathophysiological meaning remains questionable. Functional neuroimaging has suggested that, in this setting, PLEDs may indeed be an ictal pattern. In this report we describe perfusional changes in a patient with AIDS, PLEDs and NCSE.. A 37-year-old man with AIDS, cryptococcosis and recurrent epileptic seizures was admitted. After initial treatment, he remained comatose, and had MRI and serial EEG recordings performed. Technetium-99m-ethyl cysteinate dimer (99mTc-ECD) SPECT scans were also obtained, before and after continuous benzodiazepine infusion.. EEG disclosed PLEDs over the right fronto-polar region while MRI revealed meningeal thickening and scattered unspecific findings. SPECT revealed marked focal hyperperfusion overlapping the areas with PLEDs, both resolved after continuous midazolam infusion and clinical improvement.. This report demonstrates association of PLEDs, NCSE, and focal hyperperfusion on SPECT, additionally supporting the concept of PLEDs as an ictal pattern. Considering that status epilepticus may eventually not be detected by conventional approaches alone, we advocate the use of functional neuroimaging to assess suspected patients with impaired consciousness.

Topics: Acquired Immunodeficiency Syndrome; Adult; Electroencephalography; Functional Laterality; Humans; Hyperemia; Male; Periodicity; Radiopharmaceuticals; Status Epilepticus; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Cerebral hyperperfusion syndrome has been increasingly reported as a complication of carotid angioplasty and stent placement. The aim of the present study was to determine significant predictors of hyperperfusion phenomenon after carotid angioplasty and stent placement.. We retrospectively reviewed 30 consecutive patients with unilateral severe carotid stenosis who underwent angioplasty and stent placement. Resting cerebral blood flow (CBF) and cerebral vasoreactivity (CVR) to acetazolamide challenge were quantitatively measured to evaluate cerebral hemodynamic reserve. Split-dose [(123)I] iodoamphetamine single photon emission CT (SPECT) was performed before and 7 days after carotid angioplasty and stent placement. Technetium-99m hexamethylpropyleneamine oxime (HMPAO) SPECT was performed immediately after the procedure.. Three patients had cerebral hyperperfusion phenomenon immediately after angioplasty and stent placement, as shown by HMPAO SPECT: One developed status epilepticus 2 weeks after the procedure. Significant predictors of hyperperfusion included patient age, pretreatment CVR, and pretreatment asymmetry index ([ipsilateral resting CBF/contralateral resting CBF] x 100). Variables determined not to be significant risk factors included pretreatment resting CBF value, degree of carotid stenosis, and interval from the onset of ischemic symptoms.. Significant predictors of hyperperfusion phenomenon after carotid angioplasty and stent placement included patient age, pretreatment CVR, and pretreatment asymmetry index. Pretreatment CBF measurements, including those obtained by quantifying CVR and performing SPECT immediately after the procedure may aid in identifying patients at risk and in initiating careful monitoring and control of blood pressure to prevent hyperperfusion syndrome.

Topics: Acetazolamide; Aged; Aged, 80 and over; Amphetamines; Angioplasty, Balloon; Carotid Stenosis; Cerebrovascular Circulation; Cerebrovascular Disorders; Female; Hemodynamics; Humans; Hyperemia; Iodine Radioisotopes; Male; Middle Aged; Predictive Value of Tests; Radiopharmaceuticals; Retrospective Studies; Stents; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Vasomotor System

Postictal psychosis is a well-known complication, occurring especially in patients with temporal lobe epilepsy. It usually runs a benign course. The literature on this topic is sparse, and the underlying pathogenic mechanisms are not known.. We report five patients with temporal lobe epilepsy in whom postictal psychosis developed during the course of video-EEG monitoring; they were studied with hexamethyl-propyleneamine-oxime single-photon emission computed tomography (HMPAO-SPECT) during and after the psychotic event.. In comparison to the interictal state, all SPECT scans obtained during postictal psychosis were remarkable for bifrontal and bitemporal hyperperfusion patterns. Some studies also demonstrated unilateral left lateral frontal hyperperfusion. These cortical blood-flow patterns appeared to be distinct from those obtained during complex partial seizures.. Our data suggest that postictal psychoses in patients with temporal lobe epilepsy are associated with hyperactivation of both temporal and frontal lobe structures. This hyperperfusion may reflect ongoing (subcortical) discharges, active inhibitory mechanisms that terminate the seizure, or simply a dysregulation of cerebral blood flow.

Topics: Adult; Dominance, Cerebral; Electroencephalography; Epilepsy, Complex Partial; Epilepsy, Temporal Lobe; Female; Frontal Lobe; Humans; Hyperemia; Male; Monitoring, Physiologic; Neurocognitive Disorders; Risk Factors; Technetium Tc 99m Exametazime; Temporal Lobe; Tomography, Emission-Computed, Single-Photon; Video Recording

The pathophysiological relation between periodic lateralized epileptiform discharges (PLEDs) and epileptic seizures is not known and the exact causative mechanism of PLEDs still remains unclear. In this report, the authors present a case in which the EEG displayed PLEDs after a complex partial seizure. This patient, with a long history of complex partial seizures, had previously undergone right standard anterior temporal lobectomy with hippocampectomy, with a diagnosis of mesial temporal sclerosis. She had one complex partial seizure 72 days after operation and was admitted to hospital. Her brain MRI revealed changes due to temporal lobectomy and small residual posterior hippocampic anomalies. PLEDs over the right temporal lobe were seen in postictal EEGs and persisted for 4 days despite the patient's normal mental status and normal neurologic examination. Brain perfusion scintigraphy with Tc-99m-HMPAO during PLEDs was performed on the second day after the seizure, and right temporal hyperperfusion was detected. EEGs and scintigraphic imaging were repeated after cessation of PLEDs. The repeated brain scan displayed right temporal hypoperfusion. PLEDs during the postictal period may actually be an ictal pattern, and if hyperperfusion in the brain SPECT studies during PLEDs is seen, further aggressive antiepileptic drug therapy may be necessary in some cases.

Topics: Adult; Brain; Carbamazepine; Cerebrovascular Circulation; Electroencephalography; Epilepsies, Partial; Female; Humans; Hyperemia; Periodicity; Phenobarbital; Radiopharmaceuticals; Technetium Tc 99m Exametazime; Temporal Lobe; Tomography, Emission-Computed, Single-Photon

Topics: Aged; Cerebral Cortex; Embolism; Heart Diseases; Humans; Hyperemia; Ischemic Attack, Transient; Male; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Two patients with a cerebral embolism were evaluated by using both 99mTc-ethyl cysteinate dimer (ECD, or Bicisate) and 99mTc-hexamethylpropyleneamine oxime (HMPAO) single-photon emission computed tomography (SPECT). In one patient, 99mTc-ECD SPECT images revealed hypoactivity in a reflow hyperemic area where an infarct was seen later on CT scans. In another patient, a reperfused area showed hyperactivity on 99mTc-ECD SPECT without any abnormality on follow-up CT. 99mTc-ECD represents a potential agent with which to evaluate cerebral tissue viability in early reperfusion after ischemia.

Topics: Aged; Carotid Artery, Internal; Cerebral Angiography; Cerebrovascular Circulation; Cysteine; Follow-Up Studies; Frontal Lobe; Humans; Hyperemia; Intracranial Embolism and Thrombosis; Male; Middle Aged; Organotechnetium Compounds; Parietal Lobe; Radiopharmaceuticals; Remission, Spontaneous; Technetium Tc 99m Exametazime; Temporal Lobe; Tissue Survival; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed

Little is known about the effect of spontaneous reperfusion of human cerebral infarcts. Single photon emission computerised tomography (SPECT) data were analysed from a study using 99Tc(m) HMPAO (99Tc(m) hexamethylpropyleneamine oxime) in human cerebral infarction for the frequency of reperfusion and to see if it affected infarct size, oedema, haemorrhagic transformation, or functional outcome.. Fifty sequential cases of ischaemic stroke were studied with 124 99Tc(m) HMPAO SPECT at around one day, one week, and three months after stroke along with detailed clinical and functional assessments.. Visually apparent reperfusion occurred in 14 of 50 patients (28%) with a mean delay of 5.8 days and reperfusion was seen in seven others in whom it was identified on the basis of changes in perfusion deficit volume. It occurred in 13 of 23 embolic events but only in three of 23 other events. In only two cases did spontaneous reperfusion occur early enough to preserve tissue or function. Reperfusion did not otherwise reduce infarct size, or improve clinical or functional outcome, and was not associated with oedema but an association with haemorrhagic transformation was suggested. Reperfusion significantly decreased the apparent perfusion defect as measured by SPECT one week from the ictus, but was mostly non-nutritional and transient. The mean volume of tissue preserved by nutritional reperfusion was 10 cm3, but this was unequally distributed between cases. Late washout of 99Tc(m) HMPAO from areas of hyperaemic reperfusion may be a good prognostic marker but is a rare phenomenon and too insensitive to be of general applicability.. Spontaneous reperfusion after cerebral infarction occurs in 42% of cases within the first week but is associated with clinical improvement in only 2%. It has few adverse consequences although it may be associated with haemorrhagic transformation.

Topics: Activities of Daily Living; Adult; Aged; Aged, 80 and over; Brain; Cerebral Infarction; Female; Humans; Hyperemia; Male; Middle Aged; Prognosis; Prospective Studies; Radiopharmaceuticals; Reperfusion Injury; Reproducibility of Results; Sensitivity and Specificity; Technetium Tc 99m Exametazime; Time Factors; Tomography, Emission-Computed, Single-Photon

This is a case of herpes simplex encephalitis (HSE) examined with 99mTc-ethyl cysteinate dimer (ECD) and 99mTc-hexamethyl propyleneamine oxime (HMPAO) SPECT. Static images obtained with 99mTc-ECD showed a reduced tracer uptake of the temporal lobe but focal hyperactivity using 99mTc-HMPAO. Dynamic images indicated regional increase of cerebral blood perfusion with both tracers. Technetium-99m-ECD had rapid washout from the inflamed tissue, while 99mTc-HMPAO had avid uptake. Hypofixation of 99mTc-ECD leads to failure to detect the characteristic finding of temporal lobe hyperemia in acute HSE.

Topics: Acute Disease; Aged; Brain; Cysteine; Encephalitis, Viral; Female; Herpes Simplex; Humans; Hyperemia; Organotechnetium Compounds; Radiopharmaceuticals; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Focal neurological deficits after carotid endarterectomy may result from ischemia or hyperperfusion. The usefulness of single photon emission computed tomography (SPECT) for differentiating between these two mechanisms has not been previously emphasized.. An 83-year-old man experienced dysarthria and left-sided weakness immediately after undergoing endarterectomy of the right internal carotid artery. The results of computed tomography of the head were normal, and transcranial Doppler sonography showed symmetrically elevated velocities in both middle cerebral arteries. On the 1st postoperative day, the patient's deficits worsened in parallel with spontaneous increases in blood pressure, and blood pressure reduction with labetalol resulted in clinical improvement.. On the 2nd postoperative day, technetium-99-hexametazime SPECT demonstrated markedly increased flow in the right basal ganglia and inferior frontal cortex, confirming the diagnosis of cerebral hyperperfusion. The patient's deficits continued to improve with antihypertensive therapy, and SPECT performed 7 and 48 days after surgery showed gradual normalization of the focal hyperemia.. SPECT can be used to diagnose and monitor cerebral hyperperfusion after carotid endarterectomy and may be of particular value for differentiating hyperperfusion from ischemia when characteristic computed tomographic and transcranial Doppler sonographic findings are absent.

Topics: Aged; Aged, 80 and over; Blood Flow Velocity; Blood Pressure; Brain; Endarterectomy, Carotid; Humans; Hyperemia; Male; Monitoring, Physiologic; Postoperative Complications; Sensitivity and Specificity; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Discrepancies have been reported between the findings of Tc-99m HMPAO and Tc-99m ECD brain perfusion SPECT imaging. This study investigated the discrepancies in the accumulation of these tracers using dynamic SPECT to detect the super early phase of distribution. Thirteen patients with luxury perfusion or high flow states were studied with both dynamic and standard SPECT using Tc-99m HMPAO and Tc-99m ECD within 1-3 days. Standard SPECT showed discrepancies in 6 of 13 patients. Patients with meningioma and cerebral thrombosis had increased accumulation of Tc-99m HMPAO and decreased uptake of Tc-99m ECD. Patients with arteriovenous malformation, subarachnoid hemorrhage, and cavernous angioma had decreased accumulation of both tracers, but to different degrees. Dynamic SPECT showed increased or normal accumulation (i.e., essentially no discrepancy) in the first few minutes. However, Tc-99m HMPAO had a longer retention time than Tc-99m ECD in the ensuing 5-10 minutes. Dynamic SPECT revealed a similar accumulation pattern but different washout rates for the two tracers. Tc-99m HMPAO might be a more suitable tracer to detect high flow states or luxury perfusion because the findings on standard SPECT were more in agreement with those of dynamic SPECT using this tracer.

Topics: Adult; Aged; Brain; Brain Diseases; Brain Neoplasms; Cerebrovascular Circulation; Cerebrovascular Disorders; Cysteine; Female; Humans; Hyperemia; Male; Middle Aged; Organotechnetium Compounds; Radiopharmaceuticals; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Topics: Cerebral Infarction; Cerebrovascular Disorders; Follow-Up Studies; Humans; Hyperemia; Intracranial Embolism and Thrombosis; Organotechnetium Compounds; Oximes; Plasminogen Activators; Reperfusion; Technetium Tc 99m Exametazime; Thrombolytic Therapy; Tissue Plasminogen Activator; Tomography, Emission-Computed, Single-Photon

NeuroSPECT of regional cerebral blood flow (rCBF) with Tc-99m HMPAO demonstrated left temporoparietal hyperemia in two patients with acute receptive aphasia. This finding prompted further testing with electroencephalography that added to the impression of ictal dysphasia. The differential diagnosis in one case included complicated migraine. NeuroSPECT depicts blood flow abnormalities in acute aphasic disorders, either due to ischemia, which is most commonly the cause, or due to hyperemia secondary to migraine or epilepsy. The treatment and prognosis of these latter conditions differ from stroke, and thus SPECT plays a role in patient management.

Topics: Adult; Aphasia, Wernicke; Cerebrovascular Circulation; Diagnosis, Differential; Epilepsy; Female; Humans; Hyperemia; MELAS Syndrome; Middle Aged; Organotechnetium Compounds; Oximes; Parietal Lobe; Technetium Tc 99m Exametazime; Temporal Lobe; Tomography, Emission-Computed, Single-Photon

Focal post traumatic mass lesions such as contusions and intracerebral haematomas are common, and often difficult for neurosurgeons to manage, because little is known of their pathophysiology. We have mapped cerebral blood flow, and studied small vessel ultrastructure at different time points within the first three weeks of head injury, in patients with these lesions. A zone of ischaemic brain is always present around these lesions, and persists for weeks or months. This accords with astrocyte swelling and microvascular compression seen on electron microscopy. Focal zones of hyperaemia were also present in 42% of patients, within the first two weeks of injury, and this appeared only within apparently normal tissue as judged by late MRI or CT.

Topics: Astrocytes; Biopsy; Blood-Brain Barrier; Brain; Brain Concussion; Brain Damage, Chronic; Brain Injuries; Capillaries; Cerebral Hemorrhage; Endothelium, Vascular; Follow-Up Studies; Humans; Hyperemia; Microscopy, Electron, Scanning; Muscle, Smooth, Vascular; Neurologic Examination; Organotechnetium Compounds; Oximes; Regional Blood Flow; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon