Appropriate use criteria for dementia amyloid imaging in Switzerland - mini-review and statement on behalf of the Swiss Society of Nuclear Medicine and the Swiss Memory Clinics

While FDG-PET imaging of the brain for the differential diagnosis of dementia has been covered by the compulsory health insurance in Switzerland for more than a decade, beta-amyloid-PET just recently has been added to the catalogue of procedures that have been cleared for routine use, provided that a set of appropriate use criteria (AUC) be followed. To provide guidance to dementia care practitioners, the Swiss Society of Nuclear Medicine and the Swiss Memory Clinics jointly report a mini-review on beta-amyloid-PET and discuss the AUC set into effect by the Swiss Federal Office of Public Health, as well as their application and limitations.

Brain atrophy in pure and complicated hereditary spastic paraparesis: a quantitative 3D MRI study

Hereditary spastic paraparesis (HSP) is a heterogeneous group of neurodegenerative disorders with progressive lower limb spasticity, categorized into pure (p-HSP) and complicated forms (c-HSP). The purpose of this study was to evaluate if brain volumes in HSP were altered compared with a control population. Brain volumes were determined in patients suffering from HSP, including both p-HSP (n = 21) and c-HSP type (n = 12), and 30 age-matched healthy controls, using brain parenchymal fractions (BPF) calculated from 3D MRI data in an observer-independent procedure. In addition, the tissue segments of grey and white matter were analysed separately. In HSP patients, BPF were significantly reduced compared with controls both for the whole patient group (P < 0.001) and for both subgroups, indicating considerable brain atrophy. In contrast to controls who showed a decline of brain volumes with age, this physiological phenomenon was less pronounced in HSP. Therefore, global brain parenchyma reduction, involving both grey and white matter, seems to be a feature in both subtypes of HSP. Atrophy was more pronounced in c-HSP, consistent with the more severe phenotype including extramotor involvement. Thus, global brain atrophy, detected by MRI-based brain volume quantification, is a biological marker in HSP subtypes.

Topography of cerebral atrophy in early Huntington's disease: a voxel based morphometric MRI study

OBJECTIVES

To analyse grey matter changes in early stages of Huntington's disease using magnetic resonance imaging (MRI) and the technique of voxel based morphometry (VBM).

METHODS

Forty four patients with a molecularly confirmed clinical diagnosis of Huntington's disease based on the presence of motor signs were included in the study. Patients were clinically rated using the Unified Huntington's Disease Rating Scale; all were in early clinical stages of the disease (that is, Shoulson stages I and II). High resolution volume rendering MRI scans (MP-RAGE) were acquired. MRI data were volumetrically analysed in comparison to an age matched normal database by VBM, using statistical parametric mapping (SPM99).

RESULTS

In Huntington's disease, robust regional decreases in grey matter density (p<0.001, corrected for multiple comparisons)-that is, atrophy-were found bilaterally in striatal areas as well as in the hypothalamus and the opercular cortex, and unilaterally in the right paracentral lobule. The topography of striatal changes corresponded to the dorso-ventral gradient of neuronal loss described in neuropathological studies. Stratification according to clinical severity showed a more widespread involvement extending into the ventral aspects of the striatum in the group of more severely affected patients.

CONCLUSIONS

The topography of cerebral volume changes associated with Huntington's disease can be mapped using VBM. It can be shown that cerebral grey matter changes co-vary with clinical severity and CAG repeat length.

Positron emission tomography in female patients with borderline personality disorder

The pathology of Borderline personality disorder (BPD) is poorly understood and its biological basis remains largely unknown. One functional brain imaging study using [(18)F]Deoxyglucose-PET previously reported frontal and prefrontal hypometabolism. We studied brain metabolism at baseline in 12 medication-free female patients with BPD without current substance abuse or depression and 12 healthy female controls by [(18)F]Deoxyglucose-PET and statistical parametric mapping. We found significant frontal and prefrontal hypermetabolism in patients with BPD relative to controls as well as significant hypometabolism in the hippocampus and cuneus. This study demonstrated limbic and prefrontal dysfunction under resting conditions in patients with BPD by FDG-PET. Dysfunction in this network of brain regions, which has been implicated in the regulation of emotion, may underlie symptoms of BPD.

Different striatal dopamine D2 receptor occupancy in alcohol dependent patients with or without physical withdrawal symptoms --a study using IBZM-SPECT

Ten male patients with type I alcohol dependency fulfilling DSM-IV criteria for alcohol dependency were investigated twice using IBZM-SPECT after alcohol withdrawal (day 2 and day 28 after withdrawal). Five patients had a history of physical withdrawal symptoms, 5 patients had no such history. The group with physical withdrawal symptoms showed higher IBZM binding in both scans indicating differences of dopaminergic neurotransmission in different subtypes of alcohol dependency.

Hashimoto encephalopathy - is it underdiagnosed in pediatric patients?

Hashimoto encephalopathy (HE) is associated with Hashimoto thyroiditis. Clinically it presents with variable symptoms like seizures, neuropsychiatric changes or focal neurological deficits. Autoimmune phenomena are hypothesized for the pathogenesis. HE has mainly been described in the adult population. We present two 14-year-old patients who presented with recurrent seizures and mental decline. SPECT and PET scans showed distinctly pathological changes. Both patients were diagnosed with HE and improved dramatically on steroids. We feel that HE is a rare but important differential diagnosis of encephalopathy also in the pediatric population. As this disease responds well to steroids, we recommend to obtain basic thyroid function tests as well as thyroid antibodies in all cases of unexplained encephalopathy or unexplained status epilepticus.

Depressive state and regional cerebral activity in cancer patients - a preliminary study

BACKGROUND

The aim of this study was to investigate influences of depressive states, chemotherapy and existence of remaining tumors on the regional brain activity of cancer patients.

MATERIAL AND METHODS

Positron emission tomography with 18F-fluorodeoxyglucose was performed on 21 patients with various types of cancer. Their brain images were compared to 10 age- and gender-matched control data using statistical parametric mapping (SPM). The patients were subgrouped into the with and without depression based on the scores on Zung's self-rating depression scale (SDS), with and without previous chemotherapy, and with and without existence of remaining tumors.

RESULTS

Significant metabolic reduction was detected in the cingulate gyrus, prefrontal, dorsolateral prefrontal, temporoparietal cortices and basal ganglia in cancer patients. These findings were close to known lesions of major depression. Intra-group comparisons showed that these hypometabolic findings were associated with the depth of depressive state. Influences of chemotherapy and remaining tumors on the cerebral cortex seemed to be weaker than that of psychological factors.

CONCLUSIONS

The present pilot study suggests that frontal hypoactivity commonly seen in cancer patients is likely to be associated with depression rather than chemotherapy or remaining tumors. A brain mapping technique might be useful in evaluating neuropsychiatric problems in cancer patients.

Hypermetabolism in the ventrolateral thalamus in unilateral Parkinsonian resting tremor: a positron emission tomography study

Tremorogenesis in Parkinson's disease (PD) is assumed to involve a cerebral network including the thalamus. An imaging study was performed on eight PD patients with strictly unilateral resting tremor using fluorodeoxyglucose positron emission tomography coregistered to 3-dimensional magnetic resonance imaging. Increased metabolic activity of high statistical significance (P<0.001) was found in the anterior ventrolateral nuclear group of the thalamus located contralateral to the tremor side. The metabolic changes significantly covaried with tremor amplitudes. For the first time, it could be demonstrated that thalamic metabolic changes associated with tremor in PD are localized in the ventral lateral anterior nucleus (VLa). The results are discussed with respect to previous studies on tremor generation.

[Diagnosis of questionable mandibular infiltration by squamous epithelial carcinomas. 3-D 99mTc-DPD SPECT reconstruction and (18F) fluoride PET study: diagnostic advantages or unnecessary expense?]

OBJECTIVE

A prospective study was designed to compare computer-aided 3D 99mTc-DPD SPECT reconstruction, conventional 99mTc-DPD SPECT investigation (n = 88) and flurine-18 PET (n = 10) in the assessment of mandibular bone invasion by SCC.

PATIENTS/METHODS

Between 10/97 and 03/00 88 patients with SCC of the mandibular region were enrolled in this study. In 50 cases mandibular resection (segmental or marginal) was performed basing on the pretherapeutic diagnostic results.

RESULTS

No differences could be found between 3D 99mTc-DPD SPECT reconstruction and conventional 99mTc-DPD SPECT investigation. Both techniques revealed the same high sensitivity (100%) and the same specificity of 91.6 (efficiency 95.4%). Flurine-18 PET showed a sensitivity of 100%, but specificity only reached 50% (efficiency 60.0%).

CONCLUSIONS

This investigation does not provide evidence that the financial and time consuming techniques of computer-aided 3D 99mTc-DPD SPECT reconstruction and flurine-18 PET show advantages compared to conventional 99mTc-DPD SPECT investigation in the assessment of mandibular invasion by SCC.

Neuro-Behçet's syndrome in a patient not fulfilling criteria for Behçet's disease: clinical features and value of brain imaging

Central nervous system involvement is rarely an initial presenting manifestation of Behçet's disease (BD). We report the case of a 33-year-old man with recurrent attacks of fever, oral mucosal ulcers, deep venous thrombosis, diplopia, vertigo and headache. Sequential brain magnetic resonance imaging (MRI) scans showed fluctuating lesions of the brain stem, mesencephalon and thalamus. F-18-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) revealed hypometabolism at the parieto-occipital cortex at both sides and the brain stem. Treatment with prednisone and cyclosporine A led to a complete remission and normalisation of MRI and FDG-PET lesions. The present case illustrates the difficulty in the differential diagnosis of early neuro-BD.

Limbic encephalitis investigated by 18FDG-PET and 3D MRI

Two patients with clinically probable or possible limbic encephalitis (LE) are reported, both cases with typical findings in clinical symptoms (severe neuropsychological deficits and complex partial seizures) and in routine magnetic resonance imaging (MRI) (hyperintense mesiotemporal lesions). Underlying malignancy was identified (rectal carcinoma) in one case but could not be detected in the other patient. The 2 patients were investigated by cerebral 18F-fluoro-2-deoxy-D-glucose-positron emission tomography (FDG-PET) and 3-dimensional (3D) MRI, and abnormalities in metabolic activity were mapped using coregistration of spatially normalized PET and MRI. Highly significant focal hypermetabolism in bilateral hippocampal areas was found in both cases. The authors' findings support FDG-PET coregistered to 3D MRI as a potentially valuable additional tool in the imaging diagnostics of LE. Results are discussed with respect to the clinical symptoms and previously reported imaging findings in the disease.

Computer-aided 3-D 99mTc-DPD-SPECT reconstruction to assess mandibular invasion by intraoral squamous cell carcinoma: diagnostic improvement or not?

OBJECTIVE

A prospective study was designed to compare computer-aided 3-D 99mTc-DPD-SPECT (Technetium-Dicarboxy propan-single photon emission CT) reconstruction with clinical examination, panoramic radiography, CT scan and conventional 99mTc-DPD-SPECT investigation in the assessment of mandibular bone invasion by squamous cell carcinoma.

PATIENTS AND METHODS

Between October 1997 and December 1999, 88 patients with intraoral squamous cell carcinoma of the regions adjacent to the mandible were enrolled in this study. In 50 cases, mandibular resection (segmental or marginal) was performed based on the pre-treatment diagnostic results. Imaging studies were read independently by four experienced observers.

RESULTS

No differences could be found between presurgical 3-D 99mTc-DPD-SPECT reconstruction and conventional 99mTc-DPD-SPECT investigation. Both techniques revealed a sensitivity of 100% whereas CT scan showed the greatest specificity (93.8%). SPECT investigation had a specificity of 91.6% and the greatest efficiency (95.4%). The greatest predictive positive value was found for CT scan (92.3%). Clinical examination and panoramic radiography displayed the lowest sensitivity, 82.5% vs. 85.0%, and specificity, 79.2% vs. 89.5% respectively.

CONCLUSION

This investigation does not provide evidence that 3-D 99mTc-DPD-SPECT reconstruction has any advantages when compared to conventional 99mTc-DPD-ECT investigation in the assessment of mandibular invasion by squamous cell carcinoma. Despite a sensitivity of 100% the specificity is still in need of improvement. Until newer methods or techniques become available the combination of CT scanning and conventional 99mTc-DPD-SPECT investigation appears to be the best means of detecting tumour invasion preoperatively and is thus helpful in directing appropriate surgical procedure.

Evaluation of microvascular bone graft reconstruction of the head and neck with 3-D 99mTc-DPD SPECT scans

OBJECTIVE

We conducted a prospective investigation to evaluate the diagnostic accuracy of computer-aided 3-dimensional (3-D) technetium 99m dicarboxypropane methylene diphosphonate ((99m)Tc-DPD) single photon emission computed tomography (SPECT) reconstruction in the evaluation of microvascular bone flaps used for maxillofacial reconstruction.

STUDY DESIGN

Twenty patients who received 20 autogenous microvascular bone flaps for reconstruction of the mandible and maxilla were evaluated. Forty bone scans with subsequent computer-aided reconstruction were performed. Each graft could be assessed within 48 to 72 hours after surgery. The second bone scan was performed between 12 and 14 days after surgery.

RESULTS

Complications were observed in 5 grafts. SPECT investigation performed at the 2 time points after reconstruction showed a significantly higher tracer uptake in grafts with an uncomplicated further course than in those that developed complications.

CONCLUSIONS

Computer-aided 3D (99m)Tc-DPD SPECT reconstruction serves as a useful prognostic tool and helps in the very early recognition of complications. This technique adds significantly to the value of planar bone scintigraphy and conventional SPECT images.

Combined semantic dementia and apraxia in a patient with frontotemporal lobar degeneration

In this study we report neuropsychological and brain-imaging findings in a patient with frontotemporal lobar degeneration. Brain imaging using registration of (18)fluorodeoxyglucose (FDG)-PET data to three-dimensional (3-D) magnetic resonance imaging showed atrophy and highly significant hypometabolism of the left temporal lobe and both frontal lobes. Volumetric measurements of the hippocampi/amygdala showed a reduction in volume of 25% on the left compared to right within cortical areas. Neuropsychological testing revealed semantic dementia with severe anomia as well as apraxia with impairment of both recognition and production of motor acts. The implications of this case of early manifestation of frontotemporal lobar degeneration for our knowledge of dementia are discussed.

Prefrontal cortical hypometabolism during low-dose interferon alpha treatment

OBJECTIVE

To evaluate prospectively interferon alpha (IFN-alpha) associated effects on cerebral glucose metabolism and its correlation to neuropsychiatric symptoms during low-dose IFN-alpha-treatment.

METHODS

Eleven patients treated with low-dose IFN-alpha for chronic hepatitis C were prospectively evaluated by neuropsychiatric tests and cerebral [18F]deoxyglucose positron emission tomography (FDG-PET) before and in the 12th week of treatment. PET images were spatially normalized, corrected for variance in global activity and pixel-based t-statistics were calculated for each set of PET scans using SPM96 software. Pixel-cluster with P<0.001 for hypo- or hypermetabolism were displayed in parametric images. Covariance analysis with neuropsychiatric tests was calculated for each cluster.

RESULTS

In week 12 of IFN-alpha treatment, significant hypometabolism with a decrease of local activity ranging from 8 to 12% was found in all patients bilaterally in the prefrontal cortex (BA 9), which correlated in a covariate analysis with changes in depression score as measured by Beck's Depression Inventory. Additionally, hypermetabolism with a maximum increase in local activity of 6-8% was seen in all patients in putamina as well as the left occipital region (BA 18). Before IFN-alpha treatment, only 1/11 patient showed depressive symptomatology. After 3 months of treatment, 6/11 patients were classified as having mild to moderate depressive symptoms (P<0.1; Wilcoxon test).

CONCLUSIONS

Low-dose IFN-alpha therapy is associated with significant prefrontal hypometabolism. This hypometabolism covaried with depression score, but was even found in clinically non-depressed patients. These findings may reflect a possible predisposing factor for IFN-alpha associated neuropsychiatric syndromes and might contribute to a pathophysiological model of affective disorders, as endogenous IFN-alpha levels are elevated in a subset of psychotic patients during acute disease.

Alterations of cerebral glucose metabolism indicate progress to severe morphological brain lesions in neuropsychiatric systemic lupus erythematosus

Neuropsychiatric systemic lupus erythematosus (SLE) is frequently associated with deficits in brain glucose metabolism, even if morphological imaging by magnetic resonance imaging (MRI) shows no abnormalities. In these patients it is unclear whether or not the changes of brain metabolism measured by F-18-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) may progress to lesions of cerebral structure. We describe a 20-year-old woman with SLE who presented with depression, headache and impairment of memory. Initially, a cranial MRI was negative, but FDG-PET revealed significant hypometabolism in the frontal and parieto-temporo-occipital regions on both sides as well as hypermetabolism in the nuclei caudati. Within two months the patient developed an acute confusional state, seizures, visual disturbances and cranial MRI became positive showing hyperintensities at the basal ganglia and the temporo-occipital regions. Focal cerebral symptoms responded to treatment with high dose corticosteroids and brain lesions in MRI disappeared. However, a second FDG-PET showed persistent hypometabolism at frontal regions in accordance with the persistence of subclinical depression. To our knowledge, this is the first SLE case report showing that functional brain lesions visualized by FDG-PET may be a risk factor for subsequent structural brain damage seen in MRI. Thus, FDG-PET may help to verify cerebral involvement of SLE earlier than MRI.

Reproducibility of PET brain mapping of cancer patients

Twenty German cancer patients (56.9+/-12.7 years old) without brain metastasis underwent neurological PET. The acquired brain data were compared to the data of ten age and sex-matched controls (53.6+/-15. 7). Scores of Zung's Self-rating Depression Scale (SDS) obtained from 15 out of the 20 patients suggested they might be mildly depressed. Scores of Taylor's Manifest Anxiety Scale (MAS), used for additional psychological evaluation, were close to normal distribution. Hypometabolic areas in the German cancer patients were compared with those demonstrated in our previous study in Japanese cancer patients. Common findings in both studies were observed in the limbic structures, such as the anterior and posterior cingulate gyri, the basolateral frontal cortices, as well as in the basal ganglia (especially the caudate nucleus) and frontal cortex. These results are in accordance with many previous PET studies on major depression. The results show that the positron emission tomography and (18)F-fluoro-deoxyglucose ((18)FDG-PET) brain mapping results could be partially reproduced, and suggest that PET brain mapping of cancer patients has a potential clinical application to the field of psycho-oncology and cancer patient care.

Precise localization of dysfunctional areas in vertebro-basilar infarction by FDG- and O-15-H2O-PET using standardized image analysis and image registration to 3-D MR

The advantages of standardized multimodal image analysis are demonstrated in a case of symptomatic tremor after basilar thrombosis. Functionally and structurally lesioned areas were mapped in Talairach space using 3-D MRI, cerebral FDG-PET and O-15-H2O-PET. Structural lesions were found in the left midbrain, thalamus, putamen and cerebellar areas. Voxel-based statistics in comparison to a normal data base revealed hypometabolism in the left thalamus, left red nucleus, left cerebellar hemisphere including dentate nucleus and in the left inferior olivary nucleus. The O-15-H2O-PET investigation revealed metabolic uncoupling along the rubroolivocerebellar loop. Given the delicate anatomy of the structures involved, image registration and standardized image analysis techniques are essential for a synoptic multimodality analysis of morphological and functional pathology and should generally be used for cerebral PET investigations.

[3D SPECT reconstruction - a diagnostic method in oral and maxillofacial surgery]

Computer-aided three-dimensional (3D) reconstruction of conventional (99m)Tc-DPD SPECT data was used for basic investigations of different disease entities of the orofacial area, with the aim of improving primary diagnosis and, in selected cases such as microvascular bone reconstruction, for a more comprehensive control after therapy. So far, the new 3D technique has been applied in 49 patients with different indications based on commonly acquired sets of data without any further hazard for the patients. In comparison to conventional planar scintigrams, the advantage of this sophisticated technique is a higher image contrast and a clear-cut signal of the investigated bone areas without any superimposing effects. Therefore, the anatomical description of the process is better, which is particularly important in cases of osteomyelitis and after microvascular reconstruction of skull bone defects. In addition, the follow-up investigations can assess treatment results far better and outcome predictions are much more reliable. A higher sensitivity and specificity in cases of squamous cell carcinoma as regards bone infiltration could not be achieved so far. In summary, computer-aided 3D reconstruction of conventionally acquired (99m)Tc-DPD-SPECT data represents a significant improvement in radionuclide imaging technique, providing a much better diagnostic interpretation of selected disease entities in the oral and maxillofacial area.

Neuropsychiatric systemic lupus erythematosus before and after immunosuppressive treatment: a FDG PET study

At its inception, morphological imaging, like magnetic resonance imaging (MRI), is often not useful in neuropsychiatric systemic lupus erythematosus (NPSLE), although the disease clinically shows cerebral symptoms. Functional imaging, like positron emission tomography (PET), may be a method that offers some advantages. We report a 53-year-old white man with decreased memory and visual disturbances who met four of the American Rheumatism Association (ARA) criteria for the classification of SLE. He was investigated before and after 3 months of therapy using PET and F-18-fluoro-2-deoxy-D-glucose (FDG). Treatment consisted of prednisone (25 mg/day, tapered to 10 mg/day) and cyclophosphamide (daily 100 mg for 3 weeks followed by a drug-free interval of 1 week). For the control group, 15 clinically and neurologically healthy volunteers (5 male, 10 female, aged 48 +/- 7 years) were investigated. All study participants additionally had a cranial MRI. In both controls and the SLE patient, cranial MRI was negative. However, the patient showed a significant hypometabolism in the region parieto-occipital on both sides and the parietal region on the right side before treatment. After treatment metabolism in these regions was within normal limits. Hence, FDG-PET could help to verify brain-onset of SLE earlier and may be a powerful tool for controlling SLE treatment.

Brain glucose utilization in systemic lupus erythematosus with neuropsychiatric symptoms: a controlled positron emission tomography study

In contrast to morphological imaging [such as magnetic resonance imaging (MRI) or computed tomography], functional imaging may be of advantage in the detection of brain abnormalities in cases of neuropsychiatric systemic lupus erythematosus (SLE). Therefore, we studied 13 patients (aged 40+/-14 years, 11 female, 2 male) with neuropsychiatric SLE who met four of the American Rheumatism Association criteria for the classification of SLE. Ten clinically and neurologically healthy volunteers served as controls (aged 40+/-12 years, 5 female, 5 male). Both groups were investigated using fluorine-18-labelled fluorodeoxyglucose brain positron emission tomography (PET) and cranial MRI. The normal controls and 11 of the 13 patients showed normal MRI scans. However, PET scan was abnormal in all 13 SLE patients. Significant group-to-group differences in the glucose metabolic index (GMI=region of interest uptake/global uptake at the level of the basal ganglia and thalamus) were found in the parieto-occipital region on both sides: the GMI of the parieto-occipital region on the right side was 0.922+/-0.045 in patients and 1.066+/-0.081 in controls (P<<0.0001, Mann Whitney U test), while on the left side it was 0.892+/-0.060 in patients and 1. 034+/-0.051 in controls (P=0.0002). Parieto-occipital hypometabolism is a conspicuous finding in mainly MRI-negative neuropsychiatric SLE. As the parieto-occipital region is located at the boundary of blood supply of all three major arteries, it could be the most vulnerable zone of the cerebrum and may be affected at an early stage of the cerebrovascular disease.

Extended preoperative polyvinyl alcohol microembolization of intracranial meningiomas: assessment of two embolization techniques

PURPOSE

To evaluate the efficacy of preoperative meningioma devascularization with small polyvinyl alcohol (PVA) particles.

METHODS

In 34 patients with intracranial meningiomas, CT, MR, 1H MR spectroscopy, MR volumetric measurements, intraoperative ultrasound, and histopathologic findings were used to compare the efficacy of two embolization techniques: 1) administration of 150- to 300-microns PVA particles in the usual suspension, and 2) administration of 50- to 150-microns PVA particles in a highly diluted suspension.

RESULTS

Angiography after embolization demonstrated the total elimination of tumor blush in all patients. Contrast-enhanced MR after the administration of 150- to 300-microns PVA particles revealed a reduction of tumor enhancement in only two out of 14 patients. Only after the use of small particles could significant tumor necrosis be depicted on MR and confirmed histopathologically after surgery. In 12 of 20 patients, 30% to 95% of the whole tumor was necrotic with 17% to 20% reduction of tumor volume in four cases, leading to recovery from the initial neurologic deficits. In three of 20 patients without sufficient steroid medication before the treatment, tumor swelling occurred. Postembolization MR disclosed a tumor volume increase of 10% to 20% in these patients. 1H MR spectroscopy of the tumors showed an increase of lactate and aliphatic lipid compounds after embolization, indicating tumor infarction. Surgical removal of effectively embolized meningiomas without significant blood loss was possible. The appearance of the tumor at operation, ultrasound examination, and the histopathologic examination of different parts of the tumor confirmed the preoperative MR findings suggesting necrosis.

CONCLUSION

Extended microembolization with 50- to 150-microns PVA particles improves the surgical treatment of meningiomas, as compared with larger particle embolization. It may also be the only treatment required in older or high-risk patients. The protective effect of steroid medication before the endovascular treatment of meningiomas is suggested by our study.