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Targeting murine heart and brain: visualisation conditions for multi-pinhole SPECT with (99m)Tc- and (123)I-labelled probes.

Pissarek M, Meyer-Kirchrath J, Hohlfeld T, Vollmar S, Oros-Peusquens AM, Flögel U, Jacoby C, Krügel U, Schramm N - Eur. J. Nucl. Med. Mol. Imaging (2009)

Bottom Line: Alterations of maximal cerebral uptake of [(123)I]IBZM by >20% (116 kBq) were verified with the prerequisite of 50% striatal of total uptake.The labelling with [(99m)Tc]sestamibi revealed a 30% lower uptake in cardiomyopathic hearts compared to wild types. [(123)I]IPPA uptake could be visualised at activity doses of 0.8 MBq/g body weight.The thresholds of detection for differences in the tracer uptake determined under the conditions of our experiments well reflect distinctions in molar activity and uptake characteristics of the tracers.

View Article: PubMed Central - PubMed

Affiliation: Institute of Neurosciences and Biophysics-Nuclear Chemistry (INB-4), Research Centre Juelich, Leo-Brandt-Str., 52428, Juelich, Germany. m.pissarek@fz-juelich.de

ABSTRACT

Purpose: The study serves to optimise conditions for multi-pinhole SPECT small animal imaging of (123)I- and (99m)Tc-labelled radiopharmaceuticals with different distributions in murine heart and brain and to investigate detection and dose range thresholds for verification of differences in tracer uptake.

Methods: A Triad 88/Trionix system with three 6-pinhole collimators was used for investigation of dose requirements for imaging of the dopamine D(2) receptor ligand [(123)I]IBZM and the cerebral perfusion tracer [(99m)Tc]HMPAO (1.2-0.4 MBq/g body weight) in healthy mice. The fatty acid [(123)I]IPPA (0.94 +/- 0.05 MBq/g body weight) and the perfusion tracer [(99m)Tc]sestamibi (3.8 +/- 0.45 MBq/g body weight) were applied to cardiomyopathic mice overexpressing the prostaglandin EP(3) receptor.

Results: In vivo imaging and in vitro data revealed 45 kBq total cerebral uptake and 201 kBq cardiac uptake as thresholds for visualisation of striatal [(123)I]IBZM and of cardiac [(99m)Tc]sestamibi using 100 and 150 s acquisition time, respectively. Alterations of maximal cerebral uptake of [(123)I]IBZM by >20% (116 kBq) were verified with the prerequisite of 50% striatal of total uptake. The labelling with [(99m)Tc]sestamibi revealed a 30% lower uptake in cardiomyopathic hearts compared to wild types. [(123)I]IPPA uptake could be visualised at activity doses of 0.8 MBq/g body weight.

Conclusion: Multi-pinhole SPECT enables detection of alterations of the cerebral uptake of (123)I- and (99m)Tc-labelled tracers in an appropriate dose range in murine models targeting physiological processes in brain and heart. The thresholds of detection for differences in the tracer uptake determined under the conditions of our experiments well reflect distinctions in molar activity and uptake characteristics of the tracers.

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Yield obtained per detector during measurements of cardiac uptake of [99mTc]sestamibi. Data of 14 mean values of measurements in phase 1 and phase 2 and data of four ex vivo heart measurements (the four lowest values depicted) are correlated with arbitrary units obtained using the InVivoScope data processing tool. Kcps reflecting the average of counts displayed on the screen during all acquisition periods (150 s and 10 steps of rotation) are correlated with the results of the evaluation by means of the InVivoScope data processing tool. The regression line demonstrates the linearity of the multi-pinhole device
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Fig11: Yield obtained per detector during measurements of cardiac uptake of [99mTc]sestamibi. Data of 14 mean values of measurements in phase 1 and phase 2 and data of four ex vivo heart measurements (the four lowest values depicted) are correlated with arbitrary units obtained using the InVivoScope data processing tool. Kcps reflecting the average of counts displayed on the screen during all acquisition periods (150 s and 10 steps of rotation) are correlated with the results of the evaluation by means of the InVivoScope data processing tool. The regression line demonstrates the linearity of the multi-pinhole device

Mentions: The visualisation of [99mTc]sestamibi in the heart required 4–10-fold higher doses than for the 123I-labelled receptor ligands. Figure 10 shows a comparison between two hearts after application of the same activity (3.8 MBq/g body weight; for maximum intensity projections see Supplement 2A and Supplement 2B). Figure 11 shows real-time yield as kcps per detector and the respective intensity values registered within the total field of view of measurement evaluated by means of the InVivoScope processing tool (periods 1 and 2 in vivo as well as four hearts ex vivo). The high yield in the range of 3–14 kcps/detector during the in vivo measurements (in comparison to 0.5-2 kcps in the [123I]IBZM brain experiments) is predominantly due to the higher total dose activity applied in the [99mTc]sestamibi experiments. Additionally, a good correlation between in vitro data and in vivo measurements was found for the assessment of the [99mTc]sestamibi using the InVivoScope data processing tool, while data obtained by means of the Vinci 2.3.1. processing tool using only the intensities measured in the left ventricle in vivo showed a lower correlation coefficient (Fig. 12).Fig. 10


Targeting murine heart and brain: visualisation conditions for multi-pinhole SPECT with (99m)Tc- and (123)I-labelled probes.

Pissarek M, Meyer-Kirchrath J, Hohlfeld T, Vollmar S, Oros-Peusquens AM, Flögel U, Jacoby C, Krügel U, Schramm N - Eur. J. Nucl. Med. Mol. Imaging (2009)

Yield obtained per detector during measurements of cardiac uptake of [99mTc]sestamibi. Data of 14 mean values of measurements in phase 1 and phase 2 and data of four ex vivo heart measurements (the four lowest values depicted) are correlated with arbitrary units obtained using the InVivoScope data processing tool. Kcps reflecting the average of counts displayed on the screen during all acquisition periods (150 s and 10 steps of rotation) are correlated with the results of the evaluation by means of the InVivoScope data processing tool. The regression line demonstrates the linearity of the multi-pinhole device
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2724637&req=5

Fig11: Yield obtained per detector during measurements of cardiac uptake of [99mTc]sestamibi. Data of 14 mean values of measurements in phase 1 and phase 2 and data of four ex vivo heart measurements (the four lowest values depicted) are correlated with arbitrary units obtained using the InVivoScope data processing tool. Kcps reflecting the average of counts displayed on the screen during all acquisition periods (150 s and 10 steps of rotation) are correlated with the results of the evaluation by means of the InVivoScope data processing tool. The regression line demonstrates the linearity of the multi-pinhole device
Mentions: The visualisation of [99mTc]sestamibi in the heart required 4–10-fold higher doses than for the 123I-labelled receptor ligands. Figure 10 shows a comparison between two hearts after application of the same activity (3.8 MBq/g body weight; for maximum intensity projections see Supplement 2A and Supplement 2B). Figure 11 shows real-time yield as kcps per detector and the respective intensity values registered within the total field of view of measurement evaluated by means of the InVivoScope processing tool (periods 1 and 2 in vivo as well as four hearts ex vivo). The high yield in the range of 3–14 kcps/detector during the in vivo measurements (in comparison to 0.5-2 kcps in the [123I]IBZM brain experiments) is predominantly due to the higher total dose activity applied in the [99mTc]sestamibi experiments. Additionally, a good correlation between in vitro data and in vivo measurements was found for the assessment of the [99mTc]sestamibi using the InVivoScope data processing tool, while data obtained by means of the Vinci 2.3.1. processing tool using only the intensities measured in the left ventricle in vivo showed a lower correlation coefficient (Fig. 12).Fig. 10

Bottom Line: Alterations of maximal cerebral uptake of [(123)I]IBZM by >20% (116 kBq) were verified with the prerequisite of 50% striatal of total uptake.The labelling with [(99m)Tc]sestamibi revealed a 30% lower uptake in cardiomyopathic hearts compared to wild types. [(123)I]IPPA uptake could be visualised at activity doses of 0.8 MBq/g body weight.The thresholds of detection for differences in the tracer uptake determined under the conditions of our experiments well reflect distinctions in molar activity and uptake characteristics of the tracers.

View Article: PubMed Central - PubMed

Affiliation: Institute of Neurosciences and Biophysics-Nuclear Chemistry (INB-4), Research Centre Juelich, Leo-Brandt-Str., 52428, Juelich, Germany. m.pissarek@fz-juelich.de

ABSTRACT

Purpose: The study serves to optimise conditions for multi-pinhole SPECT small animal imaging of (123)I- and (99m)Tc-labelled radiopharmaceuticals with different distributions in murine heart and brain and to investigate detection and dose range thresholds for verification of differences in tracer uptake.

Methods: A Triad 88/Trionix system with three 6-pinhole collimators was used for investigation of dose requirements for imaging of the dopamine D(2) receptor ligand [(123)I]IBZM and the cerebral perfusion tracer [(99m)Tc]HMPAO (1.2-0.4 MBq/g body weight) in healthy mice. The fatty acid [(123)I]IPPA (0.94 +/- 0.05 MBq/g body weight) and the perfusion tracer [(99m)Tc]sestamibi (3.8 +/- 0.45 MBq/g body weight) were applied to cardiomyopathic mice overexpressing the prostaglandin EP(3) receptor.

Results: In vivo imaging and in vitro data revealed 45 kBq total cerebral uptake and 201 kBq cardiac uptake as thresholds for visualisation of striatal [(123)I]IBZM and of cardiac [(99m)Tc]sestamibi using 100 and 150 s acquisition time, respectively. Alterations of maximal cerebral uptake of [(123)I]IBZM by >20% (116 kBq) were verified with the prerequisite of 50% striatal of total uptake. The labelling with [(99m)Tc]sestamibi revealed a 30% lower uptake in cardiomyopathic hearts compared to wild types. [(123)I]IPPA uptake could be visualised at activity doses of 0.8 MBq/g body weight.

Conclusion: Multi-pinhole SPECT enables detection of alterations of the cerebral uptake of (123)I- and (99m)Tc-labelled tracers in an appropriate dose range in murine models targeting physiological processes in brain and heart. The thresholds of detection for differences in the tracer uptake determined under the conditions of our experiments well reflect distinctions in molar activity and uptake characteristics of the tracers.

Show MeSH
Related in: MedlinePlus