Emission Tomography Findings Research Articles

Ictal technetium-99 m ethyl cysteinate dimer single-photon emission tomographic findings in epileptic patients with polymicrogyria syndromes: A Subtraction of ictal–interictal SPECT coregistered to MRI study

To describe the ictal technetium-99 m-ECD SPECT findings in polymicrogyria syndromes (PMG) during epileptic seizures. We investigated 17 patients with PMG syndromes during presurgical workup, which included long-term video-electroencephalographic (EEG) monitoring, neurological and psychiatry assessments, invasive EEG, and the subtraction of ictal-interictal SPECT coregistered to magnetic resonance imaging (MRI) (SISCOM). The analysis of the PMG cortex, using SISCOM, revealed intense hyperperfusion in the polymicrogyric lesion during epileptic seizures in all patients. Interestingly, other localizing investigations showed heterogeneous findings. Twelve patients underwent epilepsy surgery, three achieved seizure-freedom, five have worthwhile improvement, and four patients remained unchanged. Our study strongly suggests the involvement of PMG in seizure generation or early propagation. Both conventional ictal single-photon emission computed tomography (SPECT) and SISCOM appeared as the single contributive exam to suggest the localization of the epileptogenic zone. Despite the limited number of resective epilepsy surgery in our study (n = 9), we found a strong prognostic role of SISCOM in predicting surgical outcome. This result may be of great value on surgical decision-making of whether or not the whole or part of the PMG lesion should be surgically resected.

Positron emission tomographic findings in a tuberculous brain abscess

Several case reports and studies have described the positron emission tomographic (PET) findings of intracranial tuberculomas and bacterial brain abscesses. However, to our knowledge, the PET pattern of a tuberculous brain abscess has not been previously described. We report the case of a diabetic heavy drinker with a left parietal tuberculous abscess. (18)F-fluoro-2-deoxyglucose (FDG)-PET scans showed intense FDG uptake at the abscess periphery, where contrast enhancement was observed on a magnetic resonance image. FDG uptake was reduced within the abscess cavity and in the adjacent cerebral cortex. The possibility of a tuberculous brain abscess should be considered when FDG accumulates at the periphery of a ring-enhancing lesion in a chronically ill or immunocompromised patient.

Orbitofrontal cortex hypometabolism, medication overuse headache, substance abuse and migraine: key pathophysiological issues

Sir, Professor Schoenen and colleagues show reversible metabolic changes in pain processing structures along with persistent orbitofrontal cortex (OFC) hypofunction in patients with medication overuse headache (MOH); these investigators extrapolate these positron emission tomography (PET) findings to both analgesic drug-dependence as well as to the pathogenesis of MOH itself (Fumal et al ., 2005). At the outset, the basic research premise of a causal relation between medication overuse and aggravation or transformation of primary headache disorders is uncertain and likely linked to headache frequency (Tepper and Dodick, 2002; Lipton and Bigal, 2003). The present paper (Fumal et al ., 2005) does not emphasize that: (i) Few migraine patients regularly using analgesics develop chronic daily headache (CDH) or MOH or chronic migraine. This issue needs to be distinguished from the incidence of acute medication overuse in a substantial fraction of patients with chronic headaches seen in prospective studies in specialized headache centres or the general population (Zwart et al ., 2003; Katsarava et al ., 2004). The key pathophysiological concern in MOH is not the incidence of acute medication overuse but its role in transformation of episodic migrainous headache to a more frequent/daily occurrence. Epidemiological evidence is quite unlikely to settle the cause–effect relationship between acute medication overuse and MOH or chronic migraine. (ii) While analgesic abuse is a self-determined unsupervised activity, analgesic withdrawal is a medically controlled activity—supervised analgesic withdrawal involves the placebo effect of the therapist's reassurance. Every therapeutic intervention—including supervised analgesic withdrawal—involves a placebo effect (Bignall, 1994). (iii) Analgesic withdrawal in clinical practice is commonly accompanied by other interventions undertaken simultaneously (Lipton and Bigal, 2003). (iv) No particular temporal pattern has emerged between regular analgesic use and development of daily headache in migraine …

Positron Emission Tomography in Dyke-Davidoff-Masson Syndrome

Dyke-Davidoff-Masson syndrome is clinically characterized by hemiparesis, hemiplegia, seizures, mental retardation, and facial asymmetry secondary to congenital or early childhood vascular insult. A 21-year-old man with Dyke-Davidoff-Masson syndrome presented with uncontrolled seizures. The authors present the magnetic resonance (MR) and positron emission tomography (PET) findings of this syndrome.

Relationship Between Brain Glucose Metabolism Positron Emission Tomography (PET) and Electroencephalography (EEG) in Children With Continuous Spike-and-Wave Activity During Slow-Wave Sleep

We studied the relationship between brain glucose metabolism patterns and objectively measured interictal epileptiform abnormalities in six children with intractable epilepsy and continuous spike-and-wave activity during slow-wave sleep. Five of the six patients showed lateralized positron emission tomographic (PET) findings, with the hemisphere showing a relative increase in glucose metabolism concordant with the presumed origin of the generalized interictal spike activity delineated by quantitative electroencephalographic (EEG) analysis. One of these five patients achieved seizure freedom following cortical resection involving the areas of unilateral multifocal hypermetabolism, and another patient has been approved for cortical resection. The results in the present study add further support to the hypothesis that the generalized spike-waves in most cases of continuous spike-and-wave activity during slow-wave sleep are the result of secondary bilateral synchrony. Resective surgery can be effective in selected patients with uncontrolled seizures associated with continuous spike-and-wave activity during slow-wave sleep provided that there is concordance between focal abnormalities on PET and EEG.

High 18F-fluorodeoxyglocose uptake in adrenal histoplasmosis; a case report

Adrenal histoplasmosis is one of the most common adrenal granulomatous infections in endemic areas. Although CT or MRI findings of adrenal histoplasmosis have been documented, there are no reports regarding 18F-fluorodeoxyglocose (FDG) positron emission tomography (PET) findings. We report a case of bilateral adrenal histoplasmosis showing a significantly high uptake of 18F-fluorodeoxyglocose on PET study. Adrenal histoplasmosis should be considered as one of the differential diagnoses in cases of adrenal tumors with intense FDG uptake, even in non-endemic areas.

Neuroimaging Analysis of a Case with Left Homonymous Hemianopia and Left Hemispatial Neglect

Purpose: To correlate the neuro-ophthalmological observations with the magnetic resonance images (MRI) and positron emission tomographic (PET) findings in a case with left homonymous hemianopia and left hemispatial neglect. Case: A 57-year-old woman underwent surgery for a ruptured anterior communicating artery aneurysm. After she recovered consciousness, it was found that she had left homonymous hemianopia and left hemispatial neglect. Although the hemispatial neglect slowly improved, the homonymous hemianopia persisted. MRI and measurements of cerebral glucose metabolism by 2-fluoro-2-deoxy-D-glucose(FDG)-PET were performed 1 year later. Results: MRI revealed infarctions on the medial surface of the frontal lobe, on the right medial surface of the occipital lobe, and global atrophy of the right cortical hemisphere. FDG-PET disclosed severe glucose hypometabolism in the entire right hemisphere. Glucose metabolism in the right occipital cortex was 61.1% of that in the homologous region on the left side, 62.8% in the right anterior cingulate gyrus, and 93.8% in the temporal-parietal-occipital junction. Conclusions: The low glucose metabolism in the right visual cortex explains the persistent left hemianopia, and that in the right anterior cingulate gyrus and the right temporal-parietal-occipital junction may be responsible for the left hemispatial neglect. The relatively mild damage in the right temporal-parietal-occipital junction explained the recovery of the neglect symptom. Measurements of regional cerebral glucose metabolism by PET are useful for determining the cause of cerebral visual dysfunction and its prognosis after a cerebral lesion.

Time Course and Extent of Improvement of Dysfunctioning Myocardium in Patients with Coronary Artery Disease and Severely Depressed Left Ventricular Function after Revascularization: Correlation with Positron Emission Tomographic Findings

Time Course and Extent of Improvement of Dysfunctioning Myocardium in Patients with Coronary Artery Disease and Severely Depressed Left Ventricular Function after Revascularization: Correlation with Positron Emission Tomographic Findings

Time course and extent of improvement of dysfunctioning myocardium in patients with coronary artery disease and severely depressed left ventricular function after revascularization: correlation with positron emission tomographic findings

OBJECTIVESThis study was performed to evaluate the prevalence, time course of recovery and extent of improvement of segments with a positron emission tomographic (PET) flow–metabolism mismatch and match pattern, as well as of PET segments with normal perfusion but with impaired myocardial function.BACKGROUNDPrevious studies have shown that scintigraphic techniques evaluating myocardial viability provide predictive information about the improvement of regional wall motion. However, there are little data concerning the time course and extent of improvement of segments according to preoperative scintigraphic patterns.METHODSTwenty-nine patients with ischemic cardiomyopathy (ejection fraction 18% to 35%) underwent preoperative PET viability assessment and were functionally assessed by two-dimensional echocardiography preoperatively and at 11 days, 14 weeks and >12 months after coronary artery bypass graft surgery.RESULTSIn 168 (70%) of 240 dysfunctional segments, a “normal” scintigraphic pattern was present, whereas a “mismatch” pattern was observed in 24% (p < 0.01). Mismatch areas were associated with more severe preoperative wall motion abnormalities and incomplete postoperative recovery. After one year, 31% of normal scintigraphic segments, compared with only 18% of mismatch segments, showed complete functional restoration (p < 0.05).CONCLUSIONSThese data suggest that in patients with severe left ventricular dysfunction, a scintigraphic pattern of normal perfusion and normal metabolism is more prevalent than a flow–metabolism mismatch pattern. Functional recovery is more frequent in normal scintigraphic segments, whereas in mismatch segments, postoperative recovery remains incomplete even after one year.

Clinical and brain 18fluoro-2-deoxyglucose positron emission tomographic findings in ethylmalonic aciduria, a progressive neurometabolic disease

We report a 2-year-old boy with ethylmalonic aciduria and vasculopathy syndrome evaluated by 18fluoro-2-deoxyglucose positron emission tomographic ( 18FDG PET) brain scan, with intense uptake of 18FDG in the caudate nucleus and putamen bilaterally but with no morphological changes on magnetic resonance imaging (MRI). A repeat 18FDG PET brain scan 1 year later showed a significant bilateral decreased uptake of glucose in the putamen and the head of the caudate nucleus as well as a decreased uptake in the frontal lobes. On MR[, there was atrophy and watershed infarcts in the basal ganglia, explaining the loss of glucose uptake. These results reflect a selective vulnerability of the basal ganglia, their functional derangement, and ultimate degeneration.

Dobutamine Magnetic Resonance Imaging Predicts Contractile Recovery of Chronically Dysfunctional Myocardium After Successful Revascularization

Objectives. This study sought to evaluate whether myocardial viability, as assessed by magnetic resonance imaging (MRI), reliably predicts postrevascularization left ventricular (LV) recovery.Background. Compared with positron emission tomographic findings, MRI has proved to be a reliable technique for the identification of residual myocardial viability. However, the predictive accuracy of MRI-assessed preserved end-diastolic wall thickness (DWT) and dobutamine-induced systolic wall thickening (SWT) for LV functional recovery has not yet been evaluated.Methods. Rest and low dose dobutamine MRI was performed in 43 patients with a chronic infarct (≥4 months since ischemic event) and LV dysfunction who had undergone revascularization of the infarct-related vessel. On the basis of segmental evaluation of corresponding short-axis tomograms, infarct regions were graded viable by MRI if 1) DWT was ≥5.5 mm, and 2) dobutamine-induced SWT was ≥2 mm in ≥50% of dysfunctional segments related to the infarct region. Functional recoverywas defined as SWT ≥2 mm in ≥50% of infarct-related segments at rest 4 to 6 months after successful revascularization.Results. Recovery of regional SWT could be observed in 27 (63%) of 43 patients. Comparison MRI grading before and after revascularization indicated that dobutamine-induced SWT was a better predictor of LV functional recovery (sensitivity 89%, specificity 94%) than was preserved DWT (sensitivity 92%, specificity 56%). Segments that remained akinetic after revascularization had significantly lower DWT (6.0 ± 3.1 mm [n = 219] vs. 9.8 ± 2.6 mm [n = 188], p < 0.001) than those with improved SWT. Left ventricular ejection fraction increased significantly in patients with dobutamine-induced SWT than in those with no contractile reserve (14 ± 9% vs. 3 ± 9%, p < 0.0002), and the magnitude of this increase was correlated with the number of dobutamine-responsive segments per infarct region (r = 0.68, p < 0.0001).Conclusions. Quantitative assessment of dobutamine-induced SWT in chronic infarcts by MRI is a highly accurate predictor of LV functional recovery, and the presence of significantly reduced DWT reliably indicates irreversible myocardial damage. Therefore, dobutamine stress testing for the assessment of myocardial viability can be restricted to patients with preserved DWT.

Abstracts of Literature

Abstracts of Literature

Crossed cerebellar diaschisis after middle cerebral artery infarction

It is unclear whether crossed cerebellar diaschisis (CCD) is merely an epiphenomenon, as its clinical significance remains uncertain. We retrospectively analysed the positron emission tomographic (PET) findings in 28 patients with a chronic, stable middle cerebral artery (MCA) infarct and in 22 controls, using the steady state technique and 15O. Also, the Orgogozo scores on admission and at the time of the PET examination were compared in the patients with MCA infarction. Based on the asymmetry index and the 95% confidence limits for regional cerebellar blood flow (rCBF) and oxygen consumption (rCMRO 2) in the control group, the stroke patients were subdivided in a group with ( n = 8) and a group without ( n = 20) CCD. The CCD group had lower values of rCMRO 2 in the infarct and border areas compared to those of the non-CCD patients. The infarct location within the MCA territory was similar but the size was somewhat larger in the CCC group. The degree of neurological improvement was better in the non-CCD group. Although persistence of CCD has no real clinical significance it appears to be correlated to more severe and widespread ischaemia in the affected MCA territory and to the lack of significant clinical improvement.

Looking for images of memory

AbstractThis is an excellent book but it lacks a detailed presentation and formulation of images of memory. Positron emission tomography (PET) findings sometimes raise more enigmatic questions than they answer, with differences between studies and differences with established lesion evidence. Perhaps the book could have been more critical in its analysis of these enigmas, covering more of the basic issues and assumptions underlying PET research.

Clinical outcome of patients with advanced coronary artery disease after viability studies with positron emission tomography

Objective. The aim of this study was to determine the prognostic significance of perfusion-metabolism imaging in patients undergoing positron emission tomography for myocardial viability assessment.Background. Positron emission tomography using nitrogen-13 ammonia and 18fluorodeoxyglucose to assess myocardial blood flow and metabolism has been shown to predict improvement in wall motion after coronary artery revascularization. The prognostic implications of metabolic imaging in patients with advanced coronary artery disease have not been investigated.Methods. Eighty-two patients with advanced coronary artery disease and impaired left ventricular function underwent positron emission tomographic imaging between August 1988 and March 1990 to assess myocardial viability before coronary artery revascularization.Results. Forty patients underwent successful revascularization. Patients who exhibited evidence of metabolically compromised myocardium by positron emission tomography (decreased blood flow with preserved metabolism) who did not undergo subsequent revascularization were more likely to experience a myocardial infarction, death, cardiac arrest or late revascularization due to development of new symptoms than were the other patient groups (p < 0.01). Concordantly decreased flow and metabolism in segments of previous infarction did not affect outcome in patients with or without subsequent revascularization. Those with a compromised myocardium who did undergo revascularization were more likely to experience an improvement in functional class than were patients with preoperative positron emission tomographic findings of concordant decrease in flow and metabolism.Conclusions. Positron emission tomographic myocardial viability imaging appears to identify patients at increased risk of having an adverse cardiac event or death. Patients with impaired left ventricular function and positron emission tomographic evidence for jeopardized myocardium appear to have the most benefit from a revascularization procedure.

Cerebral glucose metabolism in childhood-onset obsessive-compulsive disorder. Revisualization during pharmacotherapy.

To investigate the effects of drug treatment in childhood-onset obsessive-compulsive disorder (OCD), we repeated positron emission tomographic scans in 13 adults with OCD (eight taking clomipramine, two taking fluoxetine, and three taking no drug) after at least 1 year of pharmacotherapy. As a group, the patients had a significant improvement on all OCD and anxiety ratings. Positron emission tomography revealed a significant decrease in normalized orbitofrontal regional cerebral glucose metabolism (relative to global metabolism) bilaterally. Among the treated patients, the decrease in right orbitofrontal metabolism was directly correlated with two measures of OCD improvement. These results extend previous positron emission tomographic findings of regional dysfunction in OCD and suggest involvement of the orbitofrontal regions in the pathophysiology of OCD.

Significance of white matter lucencies in posthypoxic-ischemic encephalopathy: comparison of clinical status and of computed and positron emission tomographic findings.

The clinical status and the computed and positron tomographic findings were compared in 10 patients with sequelae of hypoxic-ischemic encephalopathy after cardiopulmonary arrest and successful resuscitation. Conscious patients with moderate neuropsychiatric deficits had no significant computed tomography (CT) scan changes and normal values of regional cerebral blood flow and oxygen consumption, while patients in vegetative state had definite cerebral atrophy on CT scan and a severe and widespread decrease of regional cerebral blood flow and oxygen consumption. This decrease was even more pronounced in vegetative patients with the worst neurological score and with CT scans demonstrating additional diffuse white matter lucencies and hypodensities in the basal ganglia. In this group of patients increased regional oxygen extraction rates mainly in the white matter indicated the occurrence of delayed ischemic changes. The positron emission tomography and CT findings correlated well with the degree of posthypoxic-ischemic damage and the clinical status of the studied subjects.

Presynaptic and postsynaptic striatal dopaminergic function in neuroacanthocytosis: A positron emission tomographic study

Using [18F]dopa, [11C]raclopride, C15O2, and positron emission tomography, we have assessed striatal dopamine storage capacity, dopamine D2-receptor integrity, and regional cerebral blood flow, respectively, of 6 patients with neuroacanthocytosis. The patients with neurocanthocytosis all had chorea and variable combinations of seizures, dementia, axonal neuropathy, and orolingual self-multiation. [18F]dopa positron emmission tomographic findings were compared with 30 normal controls and 16 patients with sporadic, L-dopa-responsive, Parkinson's disease. Caudate and anterior putamen [18F]dopa uptake were normal in patients with neuroacanthocytosis, but mean posterior putamen [18F]dopa uptake was reduced to 42% of normal, similar to that in patients with Parkinson's disease. In patients with neuroacanthocytosis, mean equilibrium caudate: cerebellum and putamen: cerebellum [11C]raclopride uptake ratios were reduced to 54% and 62% of normal, compatible with a 65% and 53% loss of caudate and putamen D2-receptor-binding sites, respectively. Striatal and frontal blood flow was also depressed. The severe loss of D2-receptor-bearing striatal neuron, with concomitant loss of dopaminergic projections from the nigra to the posterior putamen, is consistent with both chorea and extrapyramidal rigidity being features of patients with neuroacanthocytosis.

Striatal function in normal aging: Implications for Parkinson's disease

Central to several current theories of the etiology of Parkinson's disease is the premise that the nigrostriatal dopaminergic system degenerates with normal aging. Much of the evidence for this assertion has come from postmortem neurochemical studies. We have used L-6-[18F] fluoro-Dopa and positron emission tomography in 26 healthy volunteers (age range, 27-76 years) to examine striatal and frontal cortical tracer uptake. Data have been analyzed by using a graphical approach to calculate an influx constant (Ki) for L-6-[18F]fluoro-Dopa uptake into the caudate, putamen, and medial frontal cortex of each subject. In the population studied, there was no decline in Ki with age for any of these structures. A series of physiological measurements made on the older subjects also showed few significant changes with age. The positron emission tomographic findings demonstrate preservation of nigrostriatal dopaminergic function in normal aging. The pathological process causing Parkinson's disease may operate closer to the time of presentation than has been suggested.

Relation of EEG Alpha Background to Cognitive Function, Brain Atrophy, and Cerebral Metabolism in Down's Syndrome

We studied 19 young adults (19 to 37 years old) and 9 older patients (42 to 66 years old) with Down's syndrome (DS) and a control group of 13 healthy adults (22 to 38 years old) to investigate the relation of electroencephalographic (EEG) alpha background to cognitive function and cerebral metabolism. Four of the older patients with DS had a history of mental deterioration, disorientation, and memory loss and were demented. Patients and control subjects had EEGs, psychometric testing, quantitative computed tomography, and positron emission tomography with fludeoxyglucose F 18. A "blinded" reader classified the EEGs into two groups--those with normal alpha background or those with abnormal background. All the control subjects, the 13 young adult patients with DS, and the 5 older patients with DS had normal EEG backgrounds. In comparison with the age-matched patients with DS with normal alpha background, older patients with DS with decreased alpha background had dementia, fewer visuospatial skills, decreased attention span, larger third ventricles, and a global decrease in cerebral glucose utilization with parietal hypometabolism. In the young patients with DS, the EEG background did not correlate with psychometric or positron emission tomographic findings, but the third ventricles were significantly larger in those with abnormal EEG background. The young patients with DS, with or without normal EEG background, had positron emission tomographic findings similar to those of the control subjects. The mechanism underlying the abnormal EEG background may be the neuropathologic changes of Alzheimer's disease in older patients with DS and may be cerebral immaturity in younger patients with DS.