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  • 1
    Electronic Resource
    Electronic Resource
    Investigation of enzyme activities in severe burns of the anterior eye segment (1993)
    Springer
    Graefe's archive for clinical and experimental ophthalmology 231 (1993), S. 308-312 
    Details
    ISSN: 1435-702X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In severe burns of the anterior eye segment, including the cornea, limbus and adjacent conjunctiva, ischemia resulted from the necroses. While necrotic conjunctival and subconjunctival tissues may be removed to eliminate the toxic influence, the opaque cornea and ischemic sclera could not be removed. In the surrounding healthy tissues an inflammatory reaction developed, which brought about an infiltration of the damaged tissues by leukocytes and the release of lysosomal marker enzymes.N-Acetylglucosaminidase and cathepsin-d represent a number of other destructive enzymes involved with corneal and corneoscleral ulceration. Initially, their activities were low in the turbid, acellular cornea and increased 3 weeks after the burn. In the surrounding conjunctiva, these enzyme activities were normally higher than in the cornea and increased significantly after the burn. The elevated activites ofN-acetylglucosaminidase and cathepsin-d in the conjunctiva and cornea were related clinically to corneal and corneoscleral ulceration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00919110
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  • 2
    Electronic Resource
    Electronic Resource
    Tomographic studies of rCBF with99mTc-HM-PAO SPECT in comparison with PET in patients with primary brain tumors (1987)
    Springer
    Neurosurgical review 10 (1987), S. 23-24 
    Details
    ISSN: 1437-2320
    Keywords: Glioblastoma ; positron emission tomography (PET) ; regional cerebral blood flow ; single photon emission computer tomography (SPECT)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract 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 HMPAO distribution was comparable with rCBF pattern as confirmed by a significant correlation of tumor to cortex ratios. The results indicate the clinical usefulness of HMPAO for tracing rCBF in brain tumors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01780589
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  • 3
    Electronic Resource
    Electronic Resource
    The influence of image resolution on the positron emission tomographic measurement of caudate glucose consumption (1993)
    Springer
    European journal of nuclear medicine 20 (1993), S. 753-758 
    Details
    ISSN: 1619-7089
    Keywords: Positron emission tomography ; Cerebral glucose consumption ; Image resolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of this study was to investigate the influence of image resolution on (a) relative and absolute values of caudate glucose consumption (rCMRGIc) determined by positron emission tomography (PET), and (b) the detection of significant differences in these metabolic values between groups of subjects. For this purpose, raw data of cerebral accumulation of fluorine-18 fluorodeoxyglucose (FDG) obtained in 11 normal subjects and in nine patients with unilateral thalamic infarction were reconstructed using filtered backprojection with four different cut-off frequencies (CFs), yielding images with a transaxial resolution of 5.7, 7.1, 8.9 and 11 mm (full-width at half-maximum; FWHM). Absolute values of caudate rCMRGIc decreased significantly by more than 30% over the range of image resolutions studied. Bilateral ratios of caudate rCMRGIc were insensitive to variations in image resolution. Levels of significance assessing the differences in mean metabolic values between patients and controls were all below 0.01. They were, however, slightly better at image resolutions of 7.1 and 8.9 mm than at a resolution of 5.7 mm. These data indicate (a) that relative values of rCMRGIc are better suited to compare quantitative results from different PET cameras than are absolute values, and (b) that the CF used for the filtered back-projection exerts a small but not negligible influence on levels of significance assessing differences in metabolic values between groups of subjects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00180904
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  • 4
    Electronic Resource
    Electronic Resource
    Non-invasive grading of primary brain tumours: results of a comparative study between SPET with 123I-α-methyl tyrosine and PET with 18F-deoxyglucose (1997)
    Springer
    European journal of nuclear medicine 24 (1997), S. 428-434 
    Details
    ISSN: 1619-7089
    Keywords: Key words: Brain neoplasms ; Positron emission tomography ; Single-photon emission tomography ; Fluorine-18 fluorodeoxyglucose ; Iodine-123-α-methyl tyrosine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Use of iodine-123-α-methyl tyrosine (123I-IMT) allows investigation of the amino acid transport rate in gliomas. It was the aim of this study to compare the value of measurement of glucose metabolism with that of measurement of 123I-IMT uptake for the non-invasive grading of brain tumours. The study population comprised 23 patients with histopathologically proven primary brain tumours; 14 had high-grade gliomas, and nine low-grade brain neoplasms. Glucose metabolism was studied using an ECAT EXACT 47 positron emission tomography (PET) camera and fluorine-18 fluorodeoxyglucose (18F-FDG); 123I-IMT uptake was measured with the triple-headed single-photon emission tomography (SPET) camera, MULTISPECT 3. 18F-FDG and 123I-IMT uptake was quantified as ratios between the uptake by the tumour and contralateral regions of reference. Glucose metabolism and amino acid uptake of the brain tumours correlated significantly (r=0.71, P 〈0.001). Assuming discrimination thresholds between high-grade and low-grade tumours of 0.8 for 18F-FDG uptake and 1.8 for 123I-IMT uptake, the accuracy values of 18F-FDG PET and 123I-IMT SPET for differentiating between high-grade and low-grade tumours were 21/23 (91%) and 19/23 (83%), respectively. The difference in diagnostic performance was not significant on receiver operating characteristic analysis (P 〉0.4). It is concluded that there is no major difference between the PET investigation of glucose metabolism and the less expensive SPET measurement of amino acid uptake in terms of their accuracy in evaluating the malignancy grade of primary brain tumours. This encourages the performance of further studies to analyse the potential impact of 123I-IMT SPET on the therapeutic management of patients with brain tumours.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00881816
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  • 5
    Electronic Resource
    Electronic Resource
    Non-invasive grading of primary brain tumours: Results of a comparative study between SPET with123I-α-methyl tyrosine and PET with18F-deoxyglucose (1997)
    Springer
    European journal of nuclear medicine 24 (1997), S. 428-434 
    Details
    ISSN: 1619-7089
    Keywords: Brain neoplasms ; Positron emission tomography ; Single-photon emission tomography ; Fluorine-18 fluorodeoxyglucose ; Iodine-123-α-methyl tyrosine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Use of iodine-123-α-methyl tyrosine (123I-IMT) allows investigation of the amino acid transport rate in gliomas. It was the aim of this study to compare the value of measurement of glucose metabolism with that of measurement of123I-IMT uptake for the non-invasive grading of brain tumours. The study population comprised 23 patients with histopathologically proven primary brain tumours; 14 had high-grade gliomas, and nine low-grade brain neoplasms. Glucose metabolism was studied using an ECAT EXACT 47 positron emission tomography (PET) camera and fluorine-18 fluorodeoxyglucose (18F-FDG);123I-IMT uptake was measured with the triple-headed single-photon emission tomography (SPET) camera, MULTISPECT 3.18F-FDG and123I-IMT uptake was quantified as ratios between the uptake by the tumour and contralateral regions of reference. Glucose metabolism and amino acid uptake of the brain tumours correlated significantly (r=0.71,P 〈0.001). Assuming discrimination thresholds between high-grade and low-grade tumours of 0.8 for18F-FDG uptake and 1.8 for123I-IMT uptake, the accuracy values of18F-FDG PET and123I-IMT SPET for differentiating between high-grade and low-grade tumours were 21/23 (91%) and 19/23 (83%), respectively. The difference in diagnostic performance was not significant on receiver operating characteristic analysis (P 〉0.4). It is concluded that there is no major difference between the PET investigation of glucose metabolism and the less expensive SPET measurement of amino acid uptake in terms of their accuracy in evaluating the malignancy grade of primary brain tumours. This encourages the performance of further studies to analyse the potential impact of123I-IMT SPET on the therapeutic management of patients with brain tumours.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00881816
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  • 6
    Electronic Resource
    Electronic Resource
    Uptake of iodine-123-α-methyl tyrosine by gliomas and non-neoplastic brain lesions (1996)
    Springer
    European journal of nuclear medicine 23 (1996), S. 1345-1353 
    Details
    ISSN: 1619-7089
    Keywords: Brain neoplasms ; Amino acids ; Iodine-123-α-methyl tyrosine ; Radionuclide imaging ; Single-photon emission tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Using single-photon emission tomography (SPET), the radiopharmaceuticall,-3-iodine-123-α-methyl tyrosine (IMT) has been applied to the imaging of amino acid transport into brain tumours. It was the aim of this study to investigate whether IMT SPET is capable of differentiating between high-grade gliomas, low-grade gliomas and non-neoplastic brain lesions. To this end, IMT uptake was determined in 53 patients using the triple-headed SPET camera MULTISPECT 3. Twenty-eight of these subjects suffered from high-grade gliomas (WHO grade III or IV), 12 from low-grade gliomas (WHO grade II), and 13 from non-neoplastic brain lesions, including lesions after effective therapy of a glioma (five cases), infarctions (four cases), inflammatory lesions (three cases) and traumatic haematoma (one case). IMT uptake was significantly higher in high-grade gliomas than in low-grade gliomas and non-neoplastic lesions. IMT uptake by low-grade gliomas was not significantly different from that by non-neoplastic lesions. Diagnostic sensitivity and specificity were 71% and 83% for differentiating high-grade from low-grade gliomas, 82% and 100% for distinguishing high-grade gliomas from non-neoplastic lesions, and 50% and 100% for discriminating low-grade gliomas from non-neoplastic lesions. Analogously to positron emission tomography with radioactively labelled amino acids and fluorine-18 deoxyglucose, IMT SPET may aid in differentiating high-grade gliomas from histologically benign brain tumours and non-neoplastic brain lesions; it is of only limited value in differentiating between non-neoplastic lesions and histologically benign brain tumours.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01367590
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  • 7
    Electronic Resource
    Electronic Resource
    Sequential scintigraphic strategy for the differentiation of brain tumours (2000)
    Springer
    European journal of nuclear medicine 27 (2000), S. 550-558 
    Details
    ISSN: 1619-7089
    Keywords: Key words: Brain tumour – Single-photon emission tomography – Iodine-123 α-methyltyrosine – Thallium-201
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Both thallium-201 and iodine-123 α-methyltyrosine (123I-IMT) have been shown to be useful in the diagnostic evaluation of brain tumours. The aim of this study was to investigate the respective contributions of 201Tl and 123I-IMT single-photon emission tomography (SPET) in the non-invasive evaluation of intracerebral tumours. We analysed 65 patients with the following brain tumours: 8 non-neoplastic lesions, 4 meningiomas, 12 low-grade gliomas, 28 high-grade gliomas, 11 metastases and 2 high-grade lymphomas. 201Tl SPET and 123I-IMT SPET were performed [start of 201Tl SPET: 15 min p.i. (early) and 180 min p.i. (delayed); start of 123I-IMT SPET: 15 min p.i.]. The intensity of uptake was quantified as the ratio between tracer accumulation in the tumour and in the contralateral hemisphere. None of the non-neoplastic lesions or low-grade gliomas expressed marked 201Tl uptake. All malignant tumours except one small metastasis and all meningiomas except one small, cystic and degenerated lesion showed significant 201Tl accumulation [Tl(15’)〉2.0]; 123I-IMT uptake was either absent or intermediate in non-malignant lesions except in two low-grade gliomas; the highest levels were observed in high-grade gliomas followed by metastases and lymphomas (mean IMT: 2.7 vs 2.1 vs 1.8), with metastases showing a high variability in 123I-IMT uptake (range: 0.8–3.6). Using 201Tl to distinguish non-neoplastic lesions from malignant tumours and meningiomas, 63 of 65 patients were characterised correctly. In the latter group, high-grade gliomas were correctly identified in 27 of 28 cases by their amino acid uptake. It is concluded that the combination of 201Tl and 123I-IMT surpasses the accuracy of each single test in the differentiation of space-occupying lesions of the brain. Based on these preliminary results, a sequential strategy is proposed involving an initial 201Tl SPET study and an additional 123I-IMT SPET study in the event of positive 201Tl uptake.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002590050542
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  • 8
    Electronic Resource
    Electronic Resource
    Kinetics of 3-[123I]iodo-l-α-methyltyrosine transport in rat C6 glioma cells (1999)
    Springer
    European journal of nuclear medicine 26 (1999), S. 1274-1278 
    Details
    ISSN: 1619-7089
    Keywords: Key words: Rat C6 glioma cells ; l-[123I]Iodo-α-methyltyrosine ; L-system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. 3-[123I]Iodo-l-α-methyltyrosine (123I-IMT) is used for the diagnosis and monitoring of brain tumours by means of single-photon emission tomography (SPET). To date, little has been known about the system for the transport of 123I-IMT into brain tumour cells. It is assumed that 123I-IMT is transported by a specific carrier for large, neutral amino acids (L-system). In this study, rat C6 glioma cells were used to characterize the uptake system of 123I-IMT and to investigate its precise kinetics. The time course of 123I-IMT uptake into the cells was examined for a range of 1–60 min. 123I-IMT uptake rates with varying concentrations of 123I-IMT (2.5–50 µM) in the medium were quantified to assess the kinetic parameters of 123I-IMT transport. Furthermore, competition of 123I-IMT with other amino acids was investigated to identify the distinct transport systems involved in 123I-IMT uptake. 123I-IMT uptake into C6 glioma cells was linear for approximately 10 min and reached a steady-state level within 30 min. The analysis of the rate of uptake of 123I-IMT at different concentrations was concordant with the predominance of a single uptake system. The apparent Michaelis constant (K m) of 123I-IMT was 26.2±1.9 µM, and the maximum transport velocity (V max) was 35.4±1.7 nmol/mg protein per 10 min. 77%±10% of 123I-IMT transport was sodium independent and 23%±3% was sodium dependent. Competitive inhibition of 123I-IMT uptake by 2-aminobicyclo[2.2.1]heptane-2-carboxylic acid, α-(methylamino)isobutyric acid and naturally occurring amino acids revealed a major 123I-IMT transport via the sodium-independent system L (72%) and a minor uptake via the sodium-dependent system B0,+ (17%). Our results show that 123I-IMT transport into C6 glioma cells is principally mediated by the L-system and to a minor extent by the B0,+-system. The kinetic parameters of 123I-IMT uptake are in the range of those of naturally occurring amino acids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00006652
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  • 9
    Electronic Resource
    Electronic Resource
    Three-dimensional contour detection of left ventricular myocardium using elastic surfaces (1999)
    Springer
    European journal of nuclear medicine 26 (1999), S. 201-207 
    Details
    ISSN: 1619-7089
    Keywords: Key words: Myocardium ; Contour detection ; Elastic surfaces ; Positron emission tomography ; Single-photon emission tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Since the human heart has a complex anatomy, the two-dimensional analysis of myocardial scintigrams obviously is not satisfactory. Three-dimensional display can be more easily read by clinicians and depicts more accurately tracer accumulation defects. In this study we propose a three-dimensional myocardial contour detection approach using elastic surfaces. After manual reorientation into short-axis slices and transformation into heart coordinates, the myocardial mid-wall surface passing through the radial activity mass points is calculated using a second-order partial differential equation as a mathematical model. Special considerations are implemented to demarcate organs close to the heart. In a total of 1102 myocardial scintigrams the three-dimensional contour detection calculated a reasonable shape of the left ventricular myocardium in all cases. Even in areas with severe myocardial infarction, this approach was able to bridge tracer accumulation defects. Inter- and intra-observer variability tests confirmed a high reproducibility and user independence. In conclusion, in this study the proposed three-dimensional contour detection of left ventricular myocardium using elastic surfaces was found to be fast, user-independent and reliable, leading to realistic three-dimensional parametric images of myocardial scintigrams that even clinicians not experienced in nuclear cardiology can easily read.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002590050377
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  • 10
    Electronic Resource
    Electronic Resource
    Kinetics of 3-[123I]iodo-L-α-methyltyrosine transport in rat C6 glioma cells (2000)
    Springer
    European journal of nuclear medicine 27 (2000), S. 1870-1870 
    Details
    ISSN: 1619-7089
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002590000422
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