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P Bartenstein

Publications and source records attributed to P Bartenstein.

At least 91 records · Page 5Linked to original sources
PubMed1997

Fluorine-18-FDG PET and iodine-123-IMT SPECT in the evaluation of brain tumors.

UNLABELLED: The high glucose utilization of normal gray matter limits the detection of brain tumor tissue by PET using 18F-fluorodeoxyglucose (FDG). The aim of this study was to evaluate whether the examination of amino acid transport with the SPECT tracer 123l-alpha-methyl-L-tyrosine (IMT) allows better identification of tumor tissue than FDG-PET. METHODS: Nineteen patients (16 with gliomas, 3 with nontumorous lesions) were included in the study. Two independent observers classified PET and SPECT images as positive or negative for tumor tissue and defined the extent of tumor with regions of interest. Tracer uptake of FDG and IMT was quantified by calculating the tumor uptake relative to contralateral gray and white matter. RESULTS: SPECT studies were interpreted concordantly in 18 patients (kappa = 0.77) and all tumors were identified by both observers. PET studies were interpreted discordantly in 4 patients (kappa = 0.52) and only 10 tumors were identified by both observers, interobserver variability in definition of tumor extent was significantly lower in the IMT-SPECT than in the FDG-PET studies (p = 0.03). Mean tumor uptake relative to gray and white matter was 1.93 +/- 0.42 and 2.25 +/- 0.46 for IMT and 0.93 +/- 0.32 and 1.61 +/- 0.52 for FDG. All tumor uptake ratios were significantly (p < 0.01) higher for IMT than FDG, even when only glioblastomas were analyzed. No significant correlation was observed between the various uptake ratios of FDG and IMT. CONCLUSION: Despite the lower resolution and lower sensitivity of SPECT compared with PET, IMT-SPECT was clearly superior to FDG-PET in the detection and delineation of tumor tissue.

Astrocytoma↗
PubMed1997

Quantitative assessment of cerebral blood flow in patients with Alzheimer's disease by SPECT.

UNLABELLED: This study evaluated an automated analysis of SPECT brain imaging in patients with Alzheimer's disease (AD). METHODS: Patients [n = 81; mean age, 69.9 +/- 10.6 yr (mean +/- s.d.)] with a clinical diagnosis of probable AD (NINCDS-Alzheimer's Disease and Related Disorders Association criteria) underwent 99mTc-ethyl cysteine dimer SPECT imaging. After imaging registration and data extraction using three-dimensional stereotactic surface projections, a pixel-wise comparison of ethyl cysteine dimer uptake was performed using a reference database of 10 cognitive intact controls of comparable age. RESULTS: When individual cases were compared to the normal database, temporo-parietal regional cerebral blood flow (rCBF) abnormalities across different levels of dementia severity were clearly depicted on pixel-wise Z-score images. The rCBF reduction in cortical association areas showed a significant correlation with an overall level of cognitive decline, as assessed by the Mini Mental State Examination and by the cognitive section of the Cambridge Mental Disorders of the Elderly Examination. In addition, there were significant region-specific correlations between left temporo perfusion deficit and language performance and between right parietal rCBF reduction and praxis. CONCLUSION: These results indicate that this observer-independent analysis of SPECT data enables objective and semiquantitative assessment of the magnitude and extent of cortical perfusion abnormalities in patients with AD.

Alzheimer Disease↗
PubMed1996

The clinical impact of thallium-201 reinjection for the detection of myocardial hibernation.

Thallium-201 reinjection improves detection of hibernating myocardium in about 30%-50% of persisting defects. The main goal of cardiac revascularization techniques is amelioration of clinical symptoms such as angina and dyspnoea; however, improvement in regional and global pump function is an additional and important target. The aim of this study was to investigate whether fill-in in the reinjection study is correlated with improved contractile function after treatment (percutaneous transluminal coronary angioplasty/aortocoronary bypass surgery). We studied 32 patients with coronary heart disease and impaired regional wall motion (RWM). RWM and ejection fraction (EF) were assessed by analysing ventriculographic images using the centreline method (values in standard deviations from mean values found in a healthy control group). Three 201Tl single-photon emission tomographic studies (stress, redistribution and reinjection) were performed prior to revascularization and analysed using a bull s-eye scheme. Patients were divided into two groups (group FI-=no fill-in, n=16; group FI+=fill-in, n=16). Fifty-six percent of all patients showed persisting defects, and 56% of these defects showed fill-in after reinjection. Fill-in in our patient group was independent of the size of the persisting defects. After revascularization RWM increased significantly in group FI+ (from -1.9 to 0.0 SD, P<0.001) whereas group FI- showed no significant change (from -1.6 to -1.8 SD). EF increased from -4.3 preoperatively to -2.1 SD postoperatively in group FI+ and did not change significantly in group FI- (-2.5 to -3.2 SD). The predictive value of reinjection for improvement of RWM was 88%. It is concluded that fill-in in the 201Tl reinjection image can predict recovery of RWM and EF after revascularization and should be used in all patients with impaired RWM and persisting defects independent of their extent.

Adult↗
PubMed1996

Deactivation of human visual cortex during involuntary ocular oscillations. A PET activation study.

Prompted by the observation of decreased glucose metabolism in the striate and extrastriate visual cortex in a patient with opsoclonus, we studied the influence of involuntary eye movements on visual cortex activity. Repeated measurements of cerebral blood flow (CBF) by PET were performed in 12 healthy volunteers using H2(15)O-bolus technique after ear canal irrigation with ice cold or warm (44 degrees C) water with the subjects eyes closed. In addition to blood flow increases in areas involved in central vestibular processing, statistical subtraction analysis revealed a nearly symmetrical, bilateral, highly significant decrease in the occipital cortex covering Brodmann areas 17, 18, and 19 after ice water stimulation of either ears. Region of interest analysis revealed in all subjects a mean decrease in regional CBF (rCBF) of 12.8% (range 4.6-21.0%) in these areas. A similar but less pronounced effect (mean rCBF decrease in visual cortex 4.8%, range 1.1-11.5%) was observed after warm water irrigation. The observations suggest that deactivation of the visual cortex is induced by involuntary ocular oscillations. This deactivation is not dependent on changes of the retinal input (eyes closed). The physiological significance of this hitherto unknown phenomenon may be the protection from inadequate visual input (oscillopsia) during involuntary ocular oscillations.

Adult↗
PubMed1995

[Benzodiazepine receptor imaging with positron emission tomography and single photon emission tomography].

11C-Flumazenil and 123I-iomazenil are PET and SPECT ligands that bind with high affinity and selectivity to central benzodiazepine receptors. These radiopharmaceuticals are highly suitable for the localization of epileptogenic foci in partial epilepsy. With 11C-flumazenil it is possible to localize epileptogenic foci more accurately than with 18FDG. This PET ligand is also superior to the SPECT ligand and therefore with its increased availability it will possibly become more important in the presurgical assessment of patients with medically intractable temporal and especially extratemporal lobe epilepsy. Due to the high amount of cortical GABAergic synapses, 11C-flumazenil and 123I-iomazenil seem suitable as markers for the integrity of neuronal structure. With the help of these ligands, functionally disturbed areas of the brain can be differentiated from structural changes in patients with cerebral infarcts, cortical dysplasias, traumatic brain lesions or systemic degeneration. Another potential field of clinical use could be the individual pharmacological monitoring of drugs interacting with the GABAA-receptor complex. Imaging of the peripheral-type benzodiazepine receptor seems to be exclusively of scientific interest.

Brain↗
PubMed1995

[Intraoperative radiotherapy (IORT) in malignant brain tumors].

PURPOSE: Feasibility and morbidity of IORT for malignant brain tumors as well as value of innovative imaging for diagnosis of rest tumors and recurrences were examined. METHODS AND MATERIALS: Between May 1992 and November 1993, 23 patients with malignant brain tumors were treated in Münster with IORT. The patient collective was heterogeneous and negatively selected, i.e. beside of primary treatments, also patients with extensive previous treatment, recurrent tumors or metastases were included. Therapy consisted of radical surgical resection and intraoperative electron radiotherapy using total doses from 15 Gy to 25 Gy relative to the 90% isodose. Afterwards, patients without prior treatment underwent percutaneous irradiation with a maximum dose of 60 Gy, related to the small volume of the tumor area plus a safety margin of 2 cm. RESULTS: No increase of peri-operative morbidity or subacute sequelae was observed. Overall 1-year survival was 67% for grade III gliomas (WHO), and 56% for glioblastoma multiforme. When the Matsutani selection criteria (primary therapy of a supratentorial, peripheral astrocytoma grade III or glioblastoma smaller than 5 cm in diameter with a Karnofsky performance index of more than 60% and possible wide resection) were applied, 1-year survival increased to 75%. Nuclear medical diagnostics using 123I-alpha-methyltyrosin SPECT proved a valuable method for imaging of non-resectable tumor tissue and diagnosis of recurrences. CONCLUSIONS: The results of this study indicate that IORT can contribute to successful tumor treatment while neither increasing peri-operative morbidity nor subacute sequelae.

Adult↗
PubMed1994

Comparison of magnetic and metabolic brain activity during a verb generation task.

The magnetic and metabolic activational patterns of the brain during the perception, generation and silent articulation of words overlap to some extent, yet also measure concrete activational patterns. In the present study, auditory evoked magnetic fields (MEG) and changes in regional cerebral blood flow (PET) were examined in healthy subjects during a verb generation task. The aim of the study was to determine whether the advantages of both recording techniques can be combined so as to identify distributed sources of brain activity during particular tasks such as language processing. Given the currently observed disparity of the results from the two types of brain imaging we conclude that PET data will most likely not provide physiologically meaningful constraints for the distributed source analysis of MEG data, and may not necessarily validate results of distributed source analyses.

Brain↗
PubMed1994

Regional myocardial sympathetic dysinnervation in arrhythmogenic right ventricular cardiomyopathy. An analysis using 123I-meta-iodobenzylguanidine scintigraphy.

BACKGROUND: In patients with arrhythmogenic right ventricular cardiomyopathy (ARVC), the frequent provocation of ventricular tachycardia during exercise, the sensitivity toward catecholamines, and the response toward antiarrhythmic drug regimen with antiadrenergic properties suggest an involvement of the sympathetic nervous system in arrhythmogenesis. METHODS AND RESULTS: To analyze the presence, extent, and location of impaired myocardial sympathetic innervation in ARVC, 123I-meta-iodobenzylguanidine (123I-MIBG) scintigraphy was performed in 48 patients with ARVC. For comparison, 9 patients with idiopathic ventricular tachycardia and a control group of 7 patients without heart disease were investigated. In patients with ARVC, the clinical sustained (n = 25; 52%) or nonsustained (n = 23; 48%) ventricular tachycardia originated in the right ventricular outflow tract in 38 patients (79%), whereas in the remaining 10 patients (21%), the site of origin was the apical (n = 5) or inferior (n = 5) right ventricle. In 33 patients (69%), nonsustained or sustained ventricular tachycardia was provocable by exercise (n = 28 of 48; 58%) and/or by isoproterenol infusion (n = 16 of 37; 43%), whereas programmed ventricular stimulation induced sustained or nonsustained ventricular tachycardia in 16 patients each (33% each). With 123I-MIBG scintigraphy, the right ventricle was not visible in any patient. No areas of intense 123I-MIBG uptake ("hot spots") were observed. All patients of the control group and 7 of 9 patients (78%) with idiopathic ventricular tachycardia showed a uniform tracer uptake in the left ventricle. In contrast, only 8 of 48 ARVC patients (17%) showed a homogeneous distribution of 123I-MIBG uptake, whereas 40 patients (83%) demonstrated regional reductions or defects of tracer uptake. In 3 of 48 patients (6%), the defect area was < 15%; in 21 patients (44%), it was 15% to 30%; and in 16 patients (33%), it was > 30% of the polar map area of the left ventricle (mean, 23 +/- 15%; range, 0% to 57%). In 38 of 40 patients (95%) with an abnormal 123I-MIBG scan, reduced tracer uptake was located in the basal posteroseptal left ventricle, involving the adjacent lateral wall in 10, the anterior wall in 2, and the apex in 12 patients. Only 2 patients demonstrated isolated defects of the anterior or lateral wall; one involved the apex. Perfusion abnormalities in the areas of 123I-MIBG defects were excluded by stress/redistribution 201T1 single-photon emission computed tomography scintigraphy and by normal coronary angiograms in all patients. Abnormalities in 123I-MIBG scintigraphy in patients with ARVC correlated with the site of origin of ventricular tachycardia, demonstrating a regionally reduced tracer uptake in 36 of 38 patients (95%) with right ventricular outflow tract tachycardia compared with only 4 of 10 patients (40%) with other right ventricular origins of tachycardia. There was no correlation between the results of 123I-MIBG scintigraphy and the extent of right ventricular contraction abnormalities, right ventricular ejection fraction, biopsy results, coronary anatomy, or left ventricular involvement in ARVC. CONCLUSIONS: In patients with ARVC, regional abnormalities of sympathetic innervation are frequent and can be demonstrated by 123I-MIBG scintigraphy. Sympathetic denervation appears to be the underlying mechanism of reduced 123I-MIBG uptake and may be related to frequent provocation of ventricular arrhythmias by exercise or catecholamine exposure in ARVC. Therefore, in patients with ARVC, the noninvasive detection of localized sympathetic denervation by 123I-MIBG imaging may have implications for the early diagnosis and for the choice of antiarrhythmic drugs in the treatment of arrhythmias.

3-Iodobenzylguanidine↗
PubMed1994

[Comparison of D2 receptor scintigraphy (123I-IBZM) with cerebral perfusion (99m-Tc-HMPAO) in extrapyramidal disorders].

The aim of this SPECT study was to determine whether there is a correlation between rCBF (99mTc-HMPAO) and D2 receptor binding (123I-IBZM) in disorders of the extrapyramidal system and in which situation the 99mTc-HMPAO scan could predict the outcome of the 123I-IBZM study. 13 patients with Parkinson's syndrome and 13 patients with hyperkinetic extrapyramidal disorders were studied. In all patients the two SPECT studies were performed within 2-7 days. ROIs were placed over the basal ganglia (BG), the frontal cortex (FC) and the cerebellum (CE). The ratios BG/FC and BG/CE were calculated. In both groups the scatter was lower when the frontal cortex was used as reference region. Among the patients with hyperkinetic extrapyramidal disorders the two patients with Huntington's chorea had lower rCBF and D2 receptor binding compared to other hyperkinetic extrapyramidal disorders. There was no correlation between D2 receptor binding and rCBF in the basal ganglia. The 99mTc-HMPAO studies did not provide clinically useful information, except in Huntington's chorea.

Adult↗
PubMed1993

Sympathetic innervation of the left ventricle is impaired in arrhythmogenic right ventricular disease.

Arrhythmogenic right ventricular disease (ARVD) is a disease of unknown origin that primarily affects the right ventricle and is characterized by ventricular tachyarrhythmias which may lead to syncope and even, though rarely, sudden cardiac death. In 25 patients with ARVD, sympathetic innervation of the left ventricle was assessed by iodine-123 metaiodobenzylguanidine single photon emission tomography (123I-MIBG SPET). In addition, thallium-201 SPET was performed. The diagnosis of ARVD was made by an electrophysiological study and right and left heart catheterization including right ventricular endomyocardial biopsy. Ischaemic heart disease was excluded by coronary angiography. A group of seven patients without any evidence of heart disease served as a control group. Twenty-two of the 25 patients showed reduced uptake of 123I-MIBG. The abnormal areas were located predominantly in posterior and posteroseptal segments of the heart. No focus of increased 123I-MIBG activity could be demonstrated. No patient had signs of left ventricular involvement on left ventricular angiography. In contrast to the results of the 123I-MIBG SPET, those of 201T1 SPET were normal in 16 patients. The remaining nine patients showed areas of slight hypoperfusion not correlated with the reduced 123I-MIBG uptake. 123I-MIBG scintigraphy allows detection of left ventricular adrenergic dysinnervation in ARVD patients without morphological or functional abnormalities of the left ventricle.

3-Iodobenzylguanidine↗
PubMed1993

N-(2-diethylaminoethyl)-4-[123I]iodobenzamide as a tracer for the detection of malignant melanoma: simple synthesis, improved labelling technique and first clinical results.

In order to evaluate the behaviour of N-(2-diethylaminoethyl)-4-[123I]iodobenzamide in malignant melanotic disease, we synthesized the bromo compound in a simple one-step reaction. Labelling was performed by non-isotopic bromine-iodine-123 exchange in radiochemical yields up to 60%. By means of isocratic high-performance liquid chromatography, the iodinated product could be isolated with high apparent specific activity. First clinical studies in patients with malignant melanoma using N-(2-diethylaminoethyl)-4-[123I]iodobenzamide showed moderate uptake of the tracer in the tumour and the suspected metastases in all patients. Most of the lesions were detectable with technetium-99m-diethylene triamine penta-acetic acid (DTPA) scintigraphy too, but we were able to detect additional, previously unidentified metastases with benzamide scintigraphy. This changed the therapeutic procedure in two of the five cases investigated so far.

Aged↗
PubMed1993

Intraoperative, probe-guided curettage of osteoid osteoma.

The only curative approach for osteoid osteoma is operative removal of the nidus, but intraoperative detection of the nidus is difficult even when an X-ray amplifier is used. A simple probe-guided operative procedure using technetium-99m methylene diphosphonate is described, and the results and follow-up in 12 patients are reported. In addition physical properties of the probe have been evaluated by phantom measurements.

Adolescent↗
PubMed1993

Effective renal plasma flow in patients with glycogen storage disease type I.

To evaluate effective renal plasma flow (ERPF) we performed renal scintigraphies with 99mTc-Mercaptoacetyl-triglycine (MAG3) in nine patients with glycogen storage disease I (GSD I) (age: 16 +/- 7 years). Two patients presented with proteinuria, none showed hyperaminoaciduria, disturbed tubular reabsorption of phosphate or hypertension. 99mTc-MAG3 clearance values were elevated in eight out of nine patients (865 +/- 233 ml/min/1.73 m2 body surface area) and exceeded the age-dependent mean values by 21%-145%. ERPF values in patients with poor metabolic control were higher than in patients with long-term good metabolic control (988 +/- 186 vs. 619 +/- 55 ml/min/1.73 m2; P < 0.05). We conclude that enhanced ERPF is a common finding in GSD I patients, which precedes clinically overt nephropathy. Renal scintigraphy with 99mTc MAG3 is a suitable method for the early detection and monitoring of kidney dysfunction in GSD I.

Adolescent↗
PubMed1993

201Tl reinjection predicts improvement of left ventricular function following revascularization.

The aim of this study was to evaluate the correlation between improved Tl uptake in reinjection imaging with improvements in regional wall motion and global ejection fraction following PTCA or aorto-coronary bypass surgery. 19 patients with CHD were investigated and divided into two groups according to their thallium uptake in the reinjection studies. Group I showed additional uptake on reinjection imaging compared to the redistribution image, whereas group II showed no additional uptake. Both groups had a similar number and distribution of affected vessels and location of the leading stenosis. Stress, redistribution and reinjection images were obtained prior to revascularization and evaluated semiquantitatively from a bulls eye scheme. There was a postoperative increase in regional wall motion in group 1 from 5.3 to 8.8% whereas group II did not show a relevant change (6.3 vs 6.0%). The ejection fraction increased II from 55.0 to 66.7% in group I and dit not increase in group II (59.8 vs 58.7%). The overall predictive value of the reinjection image for improvement in wall motion (> 10%) was 91% and for the redistribution image 58%. Increased uptake in reinjection imaging predicts improved ventricular function following revascularization and indeed indicates viable myocardium with reversible functional impairment.

Aged↗
PubMed1992

Thallium-201 single photon emission tomography of myocardium: additional information in reinjection studies is dependent on collateral circulation.

A second thallium-201 injection under resting conditions is able to improve the differentiation between myocardial scar and ischaemia when compared with simple redistribution imaging. The aim of this study was to evaluate the dependence of this improvement on the degree of stenosis and the presence of collaterals. Single photon emission tomography (SPET) studies under exercise, redistribution and reinjection conditions were performed on 84 patients with 181 stenotic vessels (70 left anterior descending, 47 left circumflex, 64 right coronary artery) and compared with angiography. An improvement of the 201Tl uptake in the reinjection image was observed in 53% of the myocardial areas served by a coronary artery with a stenosis of over 90%. This is compared with 13% of the areas served by a vessel with a stenosis between 50% and 90%. 90% of the collateralized areas showed a fill-in effect, but only 7 of the 118 without angiographically visible collateralization (6%). The dependence of the fill-in effect, collateralization and stenosis was highly significant (chi 2 test, p less than 0.0001). In our patient group, there was much greater benefit from the reinjection study in vessels with a greater than 90% narrowing. The fill-in effect was closely correlated to the presence of collaterals. In these cases, the fill-in may be an indication for hibernating myocardium.

Collateral Circulation↗
PubMed1992

[Cortical dysplasia as an epileptogenic focus: reduced binding of 123I-iomezanil with barely perceptible 99mTc-HMPAO SPECT].

In cortical areas associated with an epileptic focus, there is, in the majority of cases, a correlation between decreased benzodiazepine (Bz) receptor binding, detectable with 123I-Iomazenil, and decreased blood flow. A patient with focal epilepsy due to a localized abnormality in cortical differentiation is presented who showed a marked focal decrease in Bz receptor binding and a normal 99mTc-HMPAO SPECT. Based on this case the relation between blood flow and Bz receptor binding in epileptic foci is discussed.

Cerebral Cortex↗