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  • 1
    Electronic Resource
    Electronic Resource
    The stereoisomers of 17α-[123I]iodovinyloestradiol and its 11α-methoxy derivative evaluated for their oestrogen receptor binding in human MCF-7 cells and rat uterus, and their distribution in immature rats (1996)
    Springer
    European journal of nuclear medicine 23 (1996), S. 295-307 
    Details
    ISSN: 1619-7089
    Keywords: 17α-[123I]iodovinyloestradiol derivatives ; Oestrogen receptor radioligand ; Breast tumour imaging ; Single-photon emission tomography ; Immature rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We studied the potential of both stereoisomers of 17α-[123I]iodovinyloestradiol (E- andZ-[123I]IVE) and of 11β-methoxy-17α-[123I]iodovinyloestradiol (E-andZ-[123I]MIVE) as suitable radioligands for the imaging of oestrogen receptor(ER)-positive human breast tumours. The 17α-[123I]iodovinyloestradiols were prepared stereospecifically by oxidative radio-iododestannylation of the corresponding 17α-tri-n-butylstannylvi-nyloestradiol precursors. Competitive binding studies were performed in order to determine the relative binding affinity (RBA) of the unlabelled 17α-iodovinyloes-tradiols for the ER in both human MCF-7 breast tumour cells and rat uterine tissue, compared with that of diethylstilboestrol (DES). Target tissue uptake, retention and uptake selectivity of their123I-labelled analogues were studied in immature female rats. All four 17α-iodovi-nyloestradiols showed high affinity for the ER in human MCF-7 cells, as well as rat uterus. Their RBA for the ER showed the following order of decreasing potency: RBA of DES 〉Z-IVE 〉Z-MIVE 〉E-MIVE ≥E-IVE. Neither of these 17α-iodovinyloestradiols showed any significant binding to the sex hormone binding globulin in human plasma. The biodistribution studies showed ER-mediated uptake in the uterus, ovaries and pituitary, that ofE- andZ-[123I]MIVE being higher than that ofE- andZ-[123I]IVE. High target-to-non-target tissue uptake ratios, especially at longer periods after injection (up to 24 h), were exhibited by both isomers of [123I]MIVE. The uterus-to-blood uptake ratio was higher forE-[123I]MIVE. However, the uterus-to-fat uptake ratio appeared to be higher for theZ-isomer of [123I]MIVE, especially at 24 h after injection. Metabolic properties and temperature effects, which play a more important role in vivo, probably cause the discrepancies seen between in vitro and in vivo binding results. On the basis of their in vitro binding properties and in vivo distribution characteristics we conclude thatE- andZ-[123I]MIVE could be suitable radioligands for the diagnostic imaging of ER in human breast cancer. Therefore, further studies with these radioligands in mature normal and tumour-bearing rats are warranted.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00837628
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  • 2
    Electronic Resource
    Electronic Resource
    Human biodistribution and dosimetry of [123I]FP-CIT: a potent radioligand for imaging of dopamine transporters (1997)
    Springer
    European journal of nuclear medicine 25 (1997), S. 24-30 
    Details
    ISSN: 1619-7089
    Keywords: Key words: Biodistribution ; Dosimetry ; Dopamine transporter imaging ; Single-photon emission tomography ; [123I]FP-CIT
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. This study reports on the biodistribution and radiation dosimetry of iodine-123-labelled N-ω-(flu- oropropyl)-2β-carbomethoxy-3β-(4-iodophenyl)tropane ([123I]FP-CIT), a promising radioligand for the imaging of dopamine transporters. In 12 healthy volunteers, conjugate whole-body scans were performed up to 48 h following intravenous injection of approximately 100 MBq [123I]FP-CIT. Attenuation correction was performed using a transmission whole-body scan obtained prior to injection of the radioligand, employing a 123I flood source. Blood samples were taken and urine was freely collected up to 48 h after injection of the radiotracer. For each subject, the percentage of injected activity measured in regions of interest over brain, striatum, lungs and liver were fitted to a multicompartmental model to give time-activity curves. The cumulative urine activity curve was used to model the urinary excretion rate and, indirectly, to predict faecal excretion. Using the MIRD method, nine source organs were considered in estimating absorbed radiation doses for organs of the body. The images showed rapid lung uptake and hepatobiliary excretion. Diffuse uptake and retention of activity was seen in the brain, especially in the striatum. At 48 h following the injection of [123I]FP-CIT, mean measured urine excretion was 60%±9% (SD), and mean predicted excretion in faeces was 14%±1%. In general, the striatum received the highest absorbed dose (average 0.23 mGy/MBq), followed by the urinary bladder wall (average 0.054 mGy/MBq) and lungs (average 0.043 mGy/MBq). The average effective dose equivalent of [123I]FP-CIT was estimated to be 0.024 mSv/MBq. The amount of [123I]FP-CIT required for adequate dopamine transporter imaging results in an acceptable effective dose equivalent to the patient.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002590050190
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  • 3
    Electronic Resource
    Electronic Resource
    Biodistribution and dosimetry of iodine-123-labelled Z-MIVE: an oestrogen receptor radioligand for breast cancer imaging (1997)
    Springer
    European journal of nuclear medicine 25 (1997), S. 40-47 
    Details
    ISSN: 1619-7089
    Keywords: Key words: 11β-Methoxy-17α-[123I]iodovinyloestradiol ; Breast cancer oestrogen receptor imaging ; Dosimetry ; Healthy female volunteer ; Single-photon emission tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. This study reports on the distribution and radiation dosimetry of iodine-123-labelled cis-11β-methoxy-17α-iodovinyloestradiol (Z-[123I]MIVE), a promising radioligand for imaging of oestrogen receptors (ERs) in human breast cancer. Whole-body scans were performed up to 24 h after intravenous injection of 138–193 MBq Z-[123I]MIVE in five healthy female volunteers, four with and one without thyroid blockade. Blood samples were taken at various times up to 24 h after injection. Urine was collected up to 24 h after injection in order to calculate renal clearance and to aid in the interpretation of whole-body clearance, including faecal excretion. Time-activity curves were generated for the thyroid, heart, brain, breasts and liver, by fitting the organ-specific geometric mean counts, obtained from regions of interest, to a multicompartmental model. The MIRD formulation, using 11 source organs, was applied to calculate the absorbed radiation doses for various organs upon administration of Z-[123I]MIVE. The images showed rapid hepatobiliary excretion which resulted in good imaging conditions for the thoracic region. Imaging of the abdominal region was impeded due to extensive bowel activity. Diffuse uptake and retention of activity was seen in breast tissue, the breast-to-non-specific uptake ratio increasing over time. Z-[123I]MIVE was cleared by both the kidneys and the gastrointestinal tract. At 50 h p.i. the mean excretion in urine was predicted to be 58%±14% (SD) and that in faeces 31%±19%. If the thyroid was not blocked, it was the most critical organ (0.33 mGy/MBq). In general, the excretory organs received the highest absorbed doses, i.e. the lower and upper large intestinal walls (0.11 and 0.098 mGy/MBq, respectively), the urinary bladder wall (0.090 mGy/MBq), the gallbladder wall (0.087 mGy/MBq) and the small intestine (0.043 mGy/MBq). The average effective dose equivalent of Z-[123I]MIVE was estimated to be 0.033 mSv/MBq. The amount of Z-[123I]MIVE required for adequate breast cancer ER imaging results in an acceptable effective dose equivalent to the patient.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002590050192
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  • 4
    Electronic Resource
    Electronic Resource
    [123I]FP-CIT binding in rat brain after acute and sub-chronic administration of dopaminergic medication (2000)
    Springer
    European journal of nuclear medicine 27 (2000), S. 346-349 
    Details
    ISSN: 1619-7089
    Keywords: Key words: [123I]FP-CIT – Dopamine transporter imaging – Animal studies – Dopaminergic medication – Parkinson’s disease – Single-photon emission tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The recently developed radioligand [123I]FP-CIT is suitable for clinical single-photon emission tomography (SPET) imaging of the dopamine (DA) transporter in vivo. To date it has remained unclear whether dopaminergic medication influences the striatal [123I]FP-CIT binding. The purpose of this study was to investigate the influence of this medication on [123I]FP-CIT binding in the brain. We used an animal model in which we administered dopaminomimetics, antipsychotics and an antidepressant. In vivo [123I]FP-CIT binding to the DA and serotonin transporters was evaluated after sub-chronic and acute administration of the drugs. The administered medication induced small changes in striatal [123I]FP-CIT binding which were not statistically significant. As expected, the DA reuptake blocker GBR 12,909 induced a significant decrease in [123I]FP-CIT binding. [123I]FP-CIT binding in the serotonin-rich hypothalamus was decreased only after acute administration of fluvoxamine. The results of this study suggest that dopaminergic medication will not affect the results of DA transporter SPET imaging with [123I]FP-CIT.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002590050044
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  • 5
    Electronic Resource
    Electronic Resource
    Iodine-123 labelled nor-β-CIT binds to the serotonin transporter in vivo as assessed by biodistribution studies in rats (1998)
    Springer
    European journal of nuclear medicine 25 (1998), S. 1666-1669 
    Details
    ISSN: 1619-7089
    Keywords: Key words: 2β-Carbomethoxy-3β-(4-iodophenyl)nortropane ; Serotonin transporter ; Biodistribution studies ; Hypothalamus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Iodine-123 labelled 2β-carbomethoxy-3β-(4-iodophenyl)nortropane (nor-β-CIT), a radioiodinated cocaine analogue, was evaluated as an agent for the in vivo labelling of serotonin transporters by biodistribution studies in rats. Intravenous injection of [123I]nor-β-CIT resulted in high accumulation of radioactivity in brain areas with high densities of serotonin (hypothalamus) and dopamine transporters (striatum), although the binding was less pronounced in the hypothalamus. While binding of [123I]nor-β-CIT in the hypothalamus was blocked significantly by fluvoxamine (a selective serotonin transporter blocker) but not by GBR12,909 (a selective dopamine transporter blocker), the opposite was observed in the striatum. The results of this study indicate that [123I]nor-β-CIT, although not being a selective radioligand, binds specifically to serotonin transporters in the hypothalamus in vivo and thus suggest that [123I]nor-β-CIT promises to be a suitable radioligand for single-photon emission tomography imaging of serotonin transporters in humans.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002590050346
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Cardiac iodine-123 metaiodobenzylguanidine uptake in animals with diabetes mellitus and/or hypertension (1996)
    Springer
    European journal of nuclear medicine 23 (1996), S. 901-908 
    Details
    ISSN: 1619-7089
    Keywords: Iodine-123 metaiodobenzylguanidine ; Rats ; Diabetes mellitus ; Hypertension ; β-Adrenoceptor density
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of the present study was to evaluate the use of the noradrenaline analogue iodine-123 metaiodobenzylguanidine ([123I]MIBG) for the assessment of cardiac sympathetic activity in the presence of diabetes mellitus and/or hypertension in animal models. One model used Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) rendered diabetic at 12 weeks of age by an intravenous injection of streptozotocin (STZ). The other model used lean and obese Zucker rats. In all groups basic haemodynamic values were established and animals received an intravenous injection of 50 μCi [123I]MIBG. Initial myocardial uptake and washout rates of [123I]MIBG were measured scintigraphically during 4 h. After sacrifice, plasma noradrenaline and left cardiac ventricular β-adrenoceptor density was determined. The diabetic state, both in STZ-treated rats (direct induction) and in obese Zucker rats (genetic induction), appeared to induce a lower cardiac density of β-adrenoceptors, indicative of increased sympathetic activity. Cardiac [123I]MIBG then showed increased washouts, thereby confirming enhanced noradrenergic activity. This parallism of results led to the conclusion that [123I]MIBG wash-out measurements could provide an excellent tool to assess cardiac sympathetic activity non-invasively. However, in hypertension (WKY vs SHR), both parameters failed to show parallelism: no changes in β-adrenoceptor density were found, whereas [123I]MIBG wash-out rate was increased. Thus, either [123I]MIBG washout or ß-adrenoceptor density may not be a reliable parameter under all circumstances to detect changes in the release of noradrenaline. Changes in the initial uptake of [123I]MIBG were observed as well. This may be a good marker for the disappearance of cardiac innervation, but it seems not to be a good parameter for distinguishing between loss of sympathetic innervation and enhanced uptake of noradrenaline in pathological conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01084363
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