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T Kuwert

Publications and source records attributed to T Kuwert.

84 records · Page 5Linked to original sources
PubMed1990

SPECT studies of brain tumors with L-3-[123I] iodo-alpha-methyl tyrosine: comparison with PET, 124IMT and first clinical results.

L-3-[123I]iodo-alpha-methyltyrosine (123IMT) like tyrosine has been reported previously to have a high affinity for a transport system in the blood-brain-barrier (BBB). We examined the kinetic behavior of 124IMT in brain and plasma in two patients with glioblastoma using dynamic positron emission tomography (PET). 124IMT accumulated in brain and tumor tissue, reaching a maximum after 15 min, with a washout of 20% to 35% at 60 min postinjection. Animal experiments confirmed the accumulation of the intact tracer in murine brain, but there was no incorporation into proteins. SPECT studies with 123IMT in patients with different types of brain tumors showed increased uptake in 26 of 32 tumors. Although nonspecific uptake in tumors must be considered, the accumulation of IMT in normal brain and in some tumors with intact BBB suggests a specific uptake of IMT. As transport is the main determinant of initial amino acid uptake, 123IMT appears to be a suitable SPECT tracer of amino acid uptake although it is not incorporated into protein.

Animals↗
PubMed1989

Investigations of brain tumours with 99Tcm-HMPAO SPECT.

The cerebral uptake of 99Tcm-hexamethylpropyleneamine oxime (99Tcm-HMPAO) as measured with the use of single photon emission computed tomography (SPECT) was studied in 66 patients with various types of brain tumours and quantified by tumour-to-cerebellum ratios. The uptake of 99Tcm-HMPAO by gliomas and meningiomas showed wide ranges of values. There were no significant differences among primary malignant gliomas (0.75 +/- 0.27, n = 25), recurrent malignant gliomas (0.81 +/- 0.25, n = 14) and benign gliomas (0.77 +/- 0.21, n = 9). Compared to gliomas, meningiomas exhibited a significantly higher 99Tcm-HMPAO uptake (1.14 +/- 0.31, n = 13, p less than 0.001) while the remaining four patients with tumours of various histopathology showed a low 99Tcm-HMPAO uptake. Three of the 66 patients were scanned immediately and again 2 h after injection and they revealed a decrease in tumour activity. No changes in the pattern of uptake were observed in two patients with gliomas which were studied before and after intra-arterial chemotherapy, but a decrease in tumour uptake was found in the glioma patient who was studied before and after radiotherapy. The results obtained with 99Tcm-HMPAO SPECT are in agreement with those on regional cerebral blood flow (rCBF) in brain tumours reported in the literature.

Brain Neoplasms↗
PubMed1989

Early effects of intra-arterial chemotherapy in patients with brain tumours studied with PET: preliminary results.

In ten patients with malignant gliomas the regional cerebral metabolic rate for glucose (rCMRGlc) was studied with positron emission tomography (PET) using 2-18F-deoxyglucose (18FDG) before and within 1 to 7 days after intra-arterial chemotherapy with the nitrosourea derivative ACNU (iaACNU). Three patients were studied before and after two iaACNU courses and one patients before and after three iaACNU courses. The early effects of iaACNU on tumour rCMRGlc were highly variable and appeared to be more pronounced after the first course of iaACNU than in later iaACNU courses, i.e. more pronounced in untreated patients. Although there was no clear correlation between the change of rCMRGlc following the first course of iaACNU and the clinical outcome in this small group of patients, the patient with the most pronounced decrease of tumour metabolism (-16.5%) after the first course of iaACNU exhibited full tumour remission for 12 months, while the patient with the most pronounced increase of tumour metabolism (+65%) after the first course of iaACNU developed rapid tumour progression. The first results indicate that early effects of intra-arterial chemotherapy may be observed with 18FDG PET, especially following the first course of iACNU. Further studies are needed to evaluate the predictive value of such studies for therapy response.

Adult↗
PubMed1988

Tomographic studies of rCBF with [99mTc]-HM-PAO SPECT in patients with brain tumors: comparison with C15O2 continuous inhalation technique and PET.

In 10 patients with malignant gliomas, the intracerebral distribution of [99mTc]-hexamethylpropylene-amine oxime [( 99mTc]-HM-PAO) was studied with single photon emission computed tomography (SPECT) in comparison with C15O2 steady-state inhalation technique to measure cerebral blood flow using positron emission tomography (PET). In all instances, the cerebral [99mTc]-HM-PAO distribution was comparable with the regional pattern of cerebral blood flow (rCBF) observed with PET. This was confirmed by a significant correlation of tumor to cortex and tumor to white matter ratios between these two experimental methods. However, the contrast between high and low activity regions in the SPECT scans was significantly less than that in the PET scans. Contrast enhancement of the SPECT scans was accomplished using a correction formula proposed by Lassen.

Brain Neoplasms↗
PubMed1987

Tomographic studies of rCBF with 99mTc-HM-PAO SPECT in comparison with PET in patients with primary brain tumors.

99mTc-hexamethyl-propyleneamine-oxime (HM-PAO) was developed as a radiotracer of regional cerebral blood flow (rCBF) with SPECT. THe purpose of this study was to investigate if HM-PAO is able to trace rCBF in primary brain tumors. In 10 patients with glioblastoma grade IV the intracerebral distribution of HM-PAO was studied in comparison with C15O2 steady state inhalation technique and PET for rCBF evaluation. In all instances the cerebral HM-PAO distribution was comparable with rCBF pattern as confirmed by a significant correlation of tumor to cortex ratios. The results indicate the clinical usefulness of HM-PAO for tracing rCBF in brain tumors.

Brain Neoplasms↗
PubMedDate not supplied

Monitoring tumor activity in low grade glioma of childhood.

Chemotherapeutic or radiotherapeutic regimens are being increasingly used in low grade glioma of childhood. These protocols require methods to monitor tumor activity. We report our experience in eleven patients. The tumors were localized in the optic pathway (3), cerebral cortex (4) and thalamus/hypothalamus (4). Histological diagnoses included low grade astrocytoma (6), gliofibroma (1) and ganglioglioma (2). Two children with neurofibromatosis type 1 (NF-1) and typical optical tumors were not biopsied. 13 episodes of progression were noted including 3 altered diagnoses. This was evident from clinical symptoms in 11/13 episodes, computed tomography (CT) or magnetic resonance imaging (MRI) in 10/13 situations, iodine-123-alpha-methyltyrosine (123I-IMT) single-photon emission computed tomography (SPECT) in 10/10 situations, fluorine-18 fluorodesoxyglucose (18F-FDG) positron emission tomography (PET) in 0/3 and thallium-201 (201Tl) SPECT in 1/1. Seven responses to chemotherapy were recorded. Clinical symptoms indicated this in 7/7 situations, MRI in 5/7, 123I-IMT SPECT in 1/2 and 201Tl SPECT in 1/1. These data suggest that 123I-IMT SPECT is a valuable addition to low grade glioma diagnostic and stress the need for a prospective study.

Adolescent↗
PubMedDate not supplied

Influence of size of regions of interest on PET evaluation of caudate glucose consumption.

The aim of this study was to analyze the influence of variations in the size of regions of interest (ROIs) on values of caudate glucose consumption [regional cerebral metabolic rate of glucose (rCMRglc)] assessed by PET. In addition, we tried to establish the influence of ROI size on levels of significance assessing differences in mean caudate glucose consumption between two groups of subjects. For this purpose, rCMRglc was measured using [18F]fluorodeoxyglucose and the PC-4096 PET camera with an in-plane resolution of 7.1 mm in 12 normal subjects and 12 subjects with early Huntington disease. Caudate rCMRglc was histographically determined using 10 different ROI widths ranging from 2 mm, corresponding to the peak value of caudate rCM-Rglc, to 20 mm. The increase in ROI width from 2 to 20 mm led to a significant decrease of caudate rCMRglc by approximately 66% in the normal subjects and in the patients. The Student t value assessing the differences in mean caudate rCMRglc between the two groups decreased gradually from 5.61 for an ROI width of 2 mm to 3.78 for an ROI width of 20 mm. This corresponds to a worsening of the level of significance from 10(-5) to 10(-3), i.e., by a factor of 100. These data show that (given the resolution of presently used PET cameras) the selection of peak values of caudate rCMRglc is the best way to discriminate between groups of subjects supposed to differ with respect to caudate rCMRglc.

Adult↗
PubMedDate not supplied

SPECT with HMPAO compared to PET with FDG in Huntington disease.

OBJECTIVE: It is the aim of this study to compare the performance of 99mTc-d,l-hexamethylpropyleneamine oxime (HMPAO) SPECT with that of [18F]fluorodeoxyglucose (FDG) PET in detecting striatal dysfunction as it occurs in Huntington disease (HD). MATERIALS AND METHODS: For the determination of regional cerebral glucose consumption, the PET camera PC-4096 was used; the cerebral uptake of HMPAO was measured using the three-head SPECT camera TRIAD. Eight patients with manifest HD, seven subjects at risk for HD, and nine normal individuals were included in the study. In both modalities data evaluation was performed using caudate-to-whole-slice (C/S) ratios. The patients' data were compared to 95% confidence intervals determined in the nine controls. RESULTS: The PET and SPECT C/S values correlated significantly (n = 24; r = 0.87; p < 0.0001). The C/S values were significantly reduced in PET in all eight and in SPECT in seven of the eight HD patients studied. Five of the seven at-risk subjects had normal C/S values in PET and SPECT, one showed reduced C/S values in both diagnostic methods, and the remaining at-risk individual showed a reduced C/S value in PET only. Thus, concordant results between PET and SPECT were obtained in seven of eight patients and six of seven at-risk subjects studied, corresponding to an 87% accuracy of SPECT in the detection of striatal dysfunction as compared to the "gold standard" PET. CONCLUSION: With use of a multidetector camera, HMPAO-SPECT comes near the performance of FDG-PET in the diagnosis of striatal dysfunction as it occurs in HD.

Adult↗
PubMedDate not supplied

Changed pattern of regional glucose metabolism during yoga meditative relaxation.

Using positron emission tomography (PET), measurements of the regional cerebral metabolic rate of glucose (rCMRGlc) are able to delineate cerebral metabolic responses to external or mental stimulation. In order to examine possible changes of brain metabolism due to Yoga meditation PET scans were performed in 8 members of a Yoga meditation group during the normal control state (C) and Yoga meditative relaxation (YMR). Whereas there were intraindividual changes of the total CMRGlc, the alterations were not significant for intergroup comparison; specific focal changes or changes in the interhemispheric differences in metabolism were also not seen; however the ratios of frontal vs. occipital rCMRGlc were significantly elevated (p less than 0.05) during YMR. These altered ratios were caused by a slight increase of frontal rCMRGlc and a more pronounced reduction in primary and secondary visual centers. These data indicate a holistic behavior of the brain metabolism during the time of altered state of consciousness during YMR.

Adult↗
PubMedDate not supplied

Localization of a pheochromocytoma using I-123 MIBG adrenal scintigraphy.

In a patient with the clinical diagnosis of pheochromocytoma, the localization of the tumor is essential for planning treatment. Recently, we have performed I-123 metaiodobenzylguanidine (MIBG) adrenal scintigraphy in a patient presenting with a history of paroxysmal hypertension. Scintigraphy accurately located an ectopic unilateral pheochromocytoma. The scintigraphic diagnosis was confirmed by surgery and a diagnosis of ectopic unilateral pheochromocytoma was made by histopathological examination. This case report illustrates the specific diagnosis of pheochromocytoma by I-123 MIBG scintigraphy which is especially useful when other diagnostic procedures are equivocal.

3-Iodobenzylguanidine↗