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  • 1
    ISSN: 1619-7089
    Keywords: Single-photon emission tomography ; Technetium-99m hexamethylpropylene amine oxime ; Computed tomography ; Method of Mountz ; Supratentorial ischaemic infarction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A comparative interim analysis was performed of clinical parameters, computed tomographic (CT) scan results and technetium-99m hexamethylpropylene amine oxime single-photon emission tomography (SPET) findings obtained within 12 h of acute supratentorial ischaemic infarction. First, the applicability for SPET semiquantification in this study of the “method of Mountz”, simultaneously accounting for extent and degrees of hypoperfusion by expressing deficits as millilitre of zero perfusion, was considered. Next, the relative contributions of perfusion SPET and CT scan in the acute stage of ischaemic infarction were compared in 27 patients (mean age 68.8 years). Finally, the correlation of SPET lesions with clinical parameters at onset was evaluated. The method of Mountz represents a workable, accurate virtual parameter, with the assumption that the contralateral brain region remains uninvolved. Interobserver reproducibility in 12 SPET studies, with lesions varying between 6 and 369 cc, showed a correlation coefficentr of 0.99. In practice, because of inconstant distribution of activities in the brain, the method can only be applied slice by slice and not on the total global volume. While the mean delay since the onset of symptomatology was approximately 7 h for both SPET and CT scan, SPET showed lesions concordant with the clinical neurological findings in 100% and CT scan in only 48%. One could hypothesize that SPET examinations performed later would show larger functional defects, because of the development of additional functional changes secondary to biochemical alterations. However, in this regard no statistically significant differences were found between two subproups, taking the median of delay before SPET examination as cut-off. Finally, when comparing the volumes of SPET lesions during the acute stage with clinical parameters, a statistically significant correlation (P〈0.01) was found with the Orgogozo Scale scores describing the neurological deficit, but not with the Glasgow Coma Scale or Frenchay Aphasia Screening Test scores obtained on admittance.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1619-7089
    Keywords: Thallium-201 ; Single-photon emission tomography ; Brain ; Tumours ; Neuro-oncology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of this retrospective study was to assess the contribution of thallium-201 single-photon emission tomography (SPET) in the detection and differential diagnosis of brain tumours. In 90 patients 201Tl SPET was performed because of clinical or radiological suspicion of tumoral invasion, completed by technetium-99m hexamethylpropylene amine oxime and 99mTc-sestamibi SPET in some patients. For all tumours, diagnosis was based on biopsy or autopsy. Other diagnoses were made only after clinical and radiological follow-up for at least 6 months. Histologically tumours consisted of astrocytoma stage I or II (number of patients, n=6), astrocytoma stage III (n=8), glioblastoma multiforme (n=14) and oligodendroglioma (n=3), brain metastasis (n=14), lymphoma (n=3), meningioma (n=3), pituitary adenoma (n=2), pineal tumour (n=1), colloid cyst (n=1) and craniopharyngioma (n=1). False-negative studies included pineal tumour (n=1), colloid cyst (n=1), craniopharyngioma (n=1), astrocytomas stage I or II (n=6) and stage III (n=3), oligodendroglioma (n=2) and metastasis in the brain stem (n=1). Additional metastases approximately 〈 1.5 cm were not detected in two patients and 201Tl SPET underestimated tumoral extent in one patient suffering from glioblastoma multiforme (n=1). A false-positive study was obtained in a patient with skull metastasis (n=l). All 15 patients who were finally shown to suffer from ischaemic infarction had a normal SPET study 9–28 days after the onset of symptomatology. Of five patients with haemorrhagic infarction, studied within 2 weeks, four were false-positive. Of six patients with intracranial haemorrhage, studied 9–39 days later, one showed focal 201Tl accumulation. Two further false-positive studies consisted of angioma and epidural haematoma. Finally, SPET studies were normal in six patients with definite diagnosis of (reactive) gliosis (n=3), Binswanger's encephalopathy (n=1), postinfectious encephalopathy (n=1) and multiple sclerosis (n=1). In the patient population presented, sensitivity of 201Tl SPET for supratentorial brain tumours was 71.7% and specificity was 80.9%. Clinical information and control SPET studies in combination with early, 30-min and 3- to 4-h delayed imaging may be expected to improve on these figures. On the other hand it seems that, in addition to tumoral histology, the presence of tumours in the fossa posterior and small volumes contribute to the occurrence of falsenegative 201Tl SPET studies.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    European journal of nuclear medicine 11 (1985), S. 17-21 
    ISSN: 1619-7089
    Keywords: Esophageal transit ; data processing ; krypton-81m
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of this work was to compare the advantages and the limitations of several data processing techniques for the assessment of esophageal transit. The following qualitative methods were evaluated: (a) scintigraphic image, (b) cine-display, (c) regional time-activity curve, and (d) condensed image. The quantitative methods evaluated were the pixel to pixel presentation of (a) parameters of the time-activity curves such as time of arrival, time to maximum, and several downslope parameters, (b) mean transit time, (c) mean time, and (d) a new transit parameter based on the radioactive decay. The study allowed us to conclude that for the detection and the quantitation of esophageal transit the method of choice was the combined use of the condensed image and the pixel to pixel mean time image. The parametric image using the transit parameter calculated from decay was shown as a valuable alternative if an ultra-short half-life radionuclide was used as the tracer.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1619-7089
    Keywords: Technetium-99m hexamethylpropylene amine oxime ; Quantification ; Phantom studies ; Brain ; Human studies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Quantitative methods for calculation of regional cerebral blood flow with technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO) have been proposed. These methods are very labour intensive and therefore are not useful in routine clinical practice. We describe a simple alternative method, using calibrated point sources as a scaling factor, whereby the tomographic slices are displayed as regional 99mTc-HMPAO brain uptake per cm3 brain tissue in 10−6 of the injected lipophilic dose. The method was validated on Jaszczak and Hoffman phantoms using a three-detector system with HR parallel and HR fan-beam collimators. Under the optimal conditions described in this paper, the measured to real activity ratio was 1.00 (SD = 0.06). The reproducibility of the cerebellar uptake in a group of ten normal volunteers and five patients was studied. Intra-individually a mean deviation of 12.6% was observed for the total group. For those persons with a heart rate difference of less than 5 units between the two studies, a mean deviation of 7.2% was obtained. Quantitative 99mTc-HMPAO brain uptake images can be useful for longitudinal studies, especially for follow-up, activation and pharmacological studies.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1619-7089
    Keywords: Technetium-99m hexamethylpropylene amine oxime ; Quantification ; Brain ; Body surface ; Heart rate ; Acetazolamide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Using calibrated point sources as an external standard to convert single-photon emission tomography (SPET) brain counts into absolute values of regional brain uptake (rBU) of technetium-99m hexamethylpropylene amine oxime (HMPAO), the relative contribution of different parameters to interindividual variability of cerebellar rBU was examined in 33 healthy volunteers. Stepwise regression analysis identified body surface as the most important factor underlying interindividual variability (P〈0.001), when compared with brain volume. In the normal volunteer population presented, age decrement of rBU corrected for body surface and brain volume equalled 60.5–0.20×age. Based on the data of eight normal volunteers, including four test-retest studies with heart rate (HR) differences greater than 5 units and four test-stress studies with doubling of heart rate after bicycle exercise, influence of heart rate may be expressed by the equation ΔrBU=0.35 ΔHR. Clinically, estimation of the relative influence of different factors allows normalization and extension of the applicability of the rBU quantification method used from longitudinal studies to group comparisons. Interestingly, results of the Daily Stress Inventory Scale and a subjective rating scale suggest the absence of a significant influence of minor stress on rBU. When using one vial per patient, chromatography may be omitted in clinical routine practice and lipophilicity may be estimated as 90% of the injected dose, if administered within 10 min after preparation. Finally, sensitivity of the quantification method was tested in eight volunteers using acetazolamide brain activation and showed a mean increase in cerebellar rBU of 30.2%, varying between 14.1% and 75.9%.
    Type of Medium: Electronic Resource
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