MIOCARDIAL PERFUSION MEASUREMENTS WITH DIFFERENT ROUTES OF DELIVERY

1
High Resolution and High Efficiency Open SPECT Detector for High Resolution and High Efficiency Open SPECT Detector for Molecular Imaging Studies of Cardiovascular Diseases on Mice Molecular Imaging Studies of Cardiovascular Diseases on Mice MIOCARDIAL PERFUSION MEASUREMENTS WITH DIFFERENT ROUTES OF DELIVERY Pin Hole: 0.5 mm Scintillator: NaI(Tl), 1.5 pitch mm thick Photodetector: H8500 (2×2) R t ~ 0.8 mm, En. Res. 14% Eff ~ 0.5 cps/μCi M ~ 3, FoV ~ 33 mm DETECTOR PROTOTYPE 0.8 mm capillaries are clearly separated on image. CONCLUSIONS and OUTLOOK Spine Liver Sistem Requirement: Overall Resolution ~ 0.8 mm Sensitivity ~ 10 cps/μCi (allowing dynamic studies and Thomographic acquisition ≤ 1 hour) Field of View ~ 25 × 25 mm 2 (mouse thoracic area dimension) Acute myocardial infarction (AMI or MI), more commonly known as a heart attack, occurs when the blood supply to a part of the heart is interrupted. The resulting ischemia or oxygen shortage causes damage and potential death of heart tissue. Diagram of a myocardial infarction (2) of the tip of the anterior wall of the heart (an apical infarct) after occlusion (1) of a branch of the left coronary artery (LCA, right coronary artery = RCA). Small Animal SPECT Imaging (mice) allows: Direct monitoring of the dynamics of the infused cells; In vivo monitoring of disease/teraphy efficacy; Translational studies SMALL ANIMAL IMAGING IN MIOCARDIAL INFARCTION THERAPHY IMPROVE RESOLUTION Gated Image Heart Rate and Volume Change affect Image Quality; Intrinsic Resolution Sub-millimetre Intrinsic resolution could be achieved with: Rugged Scintillator Material CsI(Na), CsI(Tl), pixel of 0.5 0.8 mm are available; LaBr 3 (Ce) Continuous, resolution of 0.5 0.8 mm are obtainable depending on design. This would solve IMPROVE EFFICIENCY Multi Pinhole Collimation A factor 2 4 (depends on design) Increase Number of Detector Heads A factor 48 (depends on mechanical constraint) Combine Reconstruction from Different Sets of Projections A factor 4 8 (depends on Number of Detector Heads) MOVE TO MULTIMODAL APPROACH Open System Could Be Used in Conjunction with: Optical Detector (high sensitivity) MRI (anatomical high resolution Information) to get morphological as well functional features. Magnetic field requires new photodetector technology (SiPM) Post-infarction survival has improved in recent years but NONE of the therapies is able to reverse the destructive cascade that occurs after acute myocardial infarction and lead to heart failure. Right now the results of clinical trials are somewhat disappointing: PRECLINICAL INVESTIGATION NEEDED to better understand basic mechanisms: Best cell to deliver Route of delivery Fate of stem cells Action mechanism Fig. 3 Flood field (Co-57) and pixel identification of CsI(Na) 0.8 mm pitch (a), 0.6 Fig. 3 Flood field (Co-57) and pixel identification of CsI(Na) 0.8 mm pitch (a), 0.6 mm pitc coupled to Hamamatsu H9500 mm pitc coupled to Hamamatsu H9500 Fig. 2. a) Charge sampling optimization. b) pixel identification for CsI(Na) 0.8 mm pitch Fig. 2. a) Charge sampling optimization. b) pixel identification for CsI(Na) 0.8 mm pitch coupled with H9500 Hamamatsu (3 x 3 mm2 anode pitch) and Burle MCP (1.6 x 1.6 mm2 pitch) coupled with H9500 Hamamatsu (3 x 3 mm2 anode pitch) and Burle MCP (1.6 x 1.6 mm2 pitch) Fig. 1 Spatial resolution and efficiency for Fig. 1 Spatial resolution and efficiency for High resolution based system and Anger camera High resolution based system and Anger camera based system based system M. Baiocchi M. Baiocchi 1) 1) , E. Cisbani , E. Cisbani 1) 1) , F. Cusanno , F. Cusanno 1) 1) , G. De Vincentis , G. De Vincentis 3) 3) , , F. Garibaldi F. Garibaldi 2) 2) , M.L. Magliozzi , M.L. Magliozzi 1) 1) , S. Majewski , S. Majewski 4) 4) , G. Marano , G. Marano 1) 1) , P. Musico , P. Musico 5) 5) , M. , M. Musumeci Musumeci 1) 1) , S. Torrioli , S. Torrioli 1) 1) , B. Tsui , B. Tsui 6) 6) , L. Vitelli , L. Vitelli 1) 1) 1) 1) I.S.S. ROMA (I); I.S.S. ROMA (I); 2) 2) INFN ROMA1, Roma(I), INFN ROMA1, Roma(I), 3) 3) University La Sapienza ROMA (I); University La Sapienza ROMA (I); 4) 4) West Virginia University; West Virginia University; 5) 5) I.N.F.N. Genova – via Dodecaneso, 33 – 16146 – I.N.F.N. Genova – via Dodecaneso, 33 – 16146 – GENOVA (I); GENOVA (I); 6) 6) Johns Hopkins University Johns Hopkins University SPECT systems using pinhole apertures permit radiolabeled molecular distributions to be imaged in vivo in small animals. Nevertheless studying cardiovascular SPECT systems using pinhole apertures permit radiolabeled molecular distributions to be imaged in vivo in small animals. Nevertheless studying cardiovascular diseases by means of small animal models is very challenging. Specifically, submillimeter spatial resolution, good energy resolution and high sensitivity are diseases by means of small animal models is very challenging. Specifically, submillimeter spatial resolution, good energy resolution and high sensitivity are required. We designed what we consider the “optimal” radionuclide detector system for this task. It should allow studying both detection of unstable atherosclerotic required. We designed what we consider the “optimal” radionuclide detector system for this task. It should allow studying both detection of unstable atherosclerotic plaques and monitoring the effect of therapy. The ideal system for these very challenging tasks should be an “open” and flexible one, to be integrated in plaques and monitoring the effect of therapy. The ideal system for these very challenging tasks should be an “open” and flexible one, to be integrated in multimodality with other detectors (MRI, optical). This is not possible with the system based on Anger Camera. A dedicated high resolution detector is needed. multimodality with other detectors (MRI, optical). This is not possible with the system based on Anger Camera. A dedicated high resolution detector is needed. Simulations and basic measurements have been performed with CsI(Na) scintillator arrays. Moreover, in order to understand the spatial resolution and sensitivity Simulations and basic measurements have been performed with CsI(Na) scintillator arrays. Moreover, in order to understand the spatial resolution and sensitivity needso=f and solving practical probems (route of delivery of the radiotracer) measurements have been performed both on phantoms and mice. needso=f and solving practical probems (route of delivery of the radiotracer) measurements have been performed both on phantoms and mice. a a b b We designed what we consider the “optimal” radionuclide detector system for this task, flexible enough to be integrated in a multimodality system: 8 detectors to We designed what we consider the “optimal” radionuclide detector system for this task, flexible enough to be integrated in a multimodality system: 8 detectors to optimize the trade-off between spatial resolution and sensitivity. One of these special modules is a detector with spatial resolution in the range of 300-500 optimize the trade-off between spatial resolution and sensitivity. One of these special modules is a detector with spatial resolution in the range of 300-500 μm,sensitivity of 0.3 cps/kBq, and active area 100 x 100 mm2, using tungsten pinhole collimator(s) and a high granularity scintillator (CsI(Na) with 0.8 mm pitch μm,sensitivity of 0.3 cps/kBq, and active area 100 x 100 mm2, using tungsten pinhole collimator(s) and a high granularity scintillator (CsI(Na) with 0.8 mm pitch (the smallest so far achieved for SPECT detectors) or continuous LaBr3(Ce). The reasons for the choice of the layout comes from the fact that in the SPECT with (the smallest so far achieved for SPECT detectors) or continuous LaBr3(Ce). The reasons for the choice of the layout comes from the fact that in the SPECT with multipinholes, with 3D reconstruction, a sufficient number of “resolution elements” has to be used. This translates in the need of 100-120 pixels in 100 mm, that multipinholes, with 3D reconstruction, a sufficient number of “resolution elements” has to be used. This translates in the need of 100-120 pixels in 100 mm, that means an intrinsic spatial resolution of ri = 0.8 mm – 1 mm. Scintillator arrays of very small pixels have to be used and identifying so small pixels is means an intrinsic spatial resolution of ri = 0.8 mm – 1 mm. Scintillator arrays of very small pixels have to be used and identifying so small pixels is challenging. It will require to fully exploit the characteristics of the electronics we built, capable of reading out up to ~ 4096 channels individually at 20 KHz challenging. It will require to fully exploit the characteristics of the electronics we built, capable of reading out up to ~ 4096 channels individually at 20 KHz [3]. Fig. 1 shows the advantages of the high resolution dedicated detectors with respect to Anger camera based systems. Fig. 2 shows that CsI(Na) scintillator, [3]. Fig. 1 shows the advantages of the high resolution dedicated detectors with respect to Anger camera based systems. Fig. 2 shows that CsI(Na) scintillator, 0.8 mm pitch can be used if coupled to Hamamatsu H9500 PSPMT (3 x 3 mm2 pitch), but sampling the light with smaller anode pixel size improves the pixel 0.8 mm pitch can be used if coupled to Hamamatsu H9500 PSPMT (3 x 3 mm2 pitch), but sampling the light with smaller anode pixel size improves the pixel identification. Nevertheless some problem arise in the dead area between the PSPMT’s. Continuous LaBr3(Ce) could solve the problem of dead area. Fig. 3 shows the identification. Nevertheless some problem arise in the dead area between the PSPMT’s. Continuous LaBr3(Ce) could solve the problem of dead area. Fig. 3 shows the measurements results that validate the simulation. measurements results that validate the simulation. The assessment of myocardial perfusion plays an important role in the diagnosys and in guiding therapy. In order to determine the spatial resolution,sensitivity and The assessment of myocardial perfusion plays an important role in the diagnosys and in guiding therapy. In order to determine the spatial resolution,sensitivity and energy resolution needed for this task as well as to study animal handling issues we used a single head high-resolution detector prototype, having performances energy resolution needed for this task as well as to study animal handling issues we used a single head high-resolution detector prototype, having performances close to the requested ones (NaI(Tl) 1.5 mm pitch 100 x 100 mm2, coupled to PSPMT Hamamatsu H8500 (see Fig. 4)). The performances are shown in Fig. 4. This detector close to the requested ones (NaI(Tl) 1.5 mm pitch 100 x 100 mm2, coupled to PSPMT Hamamatsu H8500 (see Fig. 4)). The performances are shown in Fig. 4. This detector allowed performing important perfusion measurement in mice, using differ routes of delivery. In fact using mice is particularly challenging in situations that allowed performing important perfusion measurement in mice, using differ routes of delivery. In fact using mice is particularly challenging in situations that require several intravenous injections of radiotracers, possibly for week or even months, in chronically ill animal. This study has evaluated the feasibility of require several intravenous injections of radiotracers, possibly for week or even months, in chronically ill animal. This study has evaluated the feasibility of assessing left ventricular perfusion by intraperitoneal delivering of MIBI-Tc in healthy mice. In Fig. 5 a we show images of the mouse-injected trough the tail assessing left ventricular perfusion by intraperitoneal delivering of MIBI-Tc in healthy mice. In Fig. 5 a we show images of the mouse-injected trough the tail vein; transverse, sagittal and coronal views are shown. The other mouse (Fig 5 b had the radiotracer injected peritoneally. The procedures were the same. The result vein; transverse, sagittal and coronal views are shown. The other mouse (Fig 5 b had the radiotracer injected peritoneally. The procedures were the same. The result shows that injecting the radiotracer through the peritoneum instead of the tail vein allows obtaining a good perfusion. The price to be payed is a reduction of the shows that injecting the radiotracer through the peritoneum instead of the tail vein allows obtaining a good perfusion. The price to be payed is a reduction of the uptake by the heart. The sensitivity of the system has to be increased to compensate the reduction. This can be obtained by fine-tuning the parameters (the hole uptake by the heart. The sensitivity of the system has to be increased to compensate the reduction. This can be obtained by fine-tuning the parameters (the hole dimension and the magnification), using the multipinhole technique and adding as many detectors as possible to the system. dimension and the magnification), using the multipinhole technique and adding as many detectors as possible to the system. Transverse, sagittal and Transverse, sagittal and coronal heart views. Tail coronal heart views. Tail vein injection vein injection Transverse, sagittal and Transverse, sagittal and coronal heart views. coronal heart views. Peritoneal injection Peritoneal injection 1.3 mm 1.2 mm 1.1 mm 1.0 mm 0.9 mm 0.8 mm This paper describes the research started by our collaboration in outlining the best detectors suited for cardiovascular diseases study on mice and the preliminary This paper describes the research started by our collaboration in outlining the best detectors suited for cardiovascular diseases study on mice and the preliminary perfusion measurements, with an high resolution detector prototype, comparing the uptake of Tc-MIBI with the two modalities: tail vein and peritoneum. perfusion measurements, with an high resolution detector prototype, comparing the uptake of Tc-MIBI with the two modalities: tail vein and peritoneum. The spatial The spatial resolution of the prototype showed to be sufficient for perfusion studies. The energy resolution allows using dual tracers techniques resolution of the prototype showed to be sufficient for perfusion studies. The energy resolution allows using dual tracers techniques . We demonstrated that . We demonstrated that injecting the radiotracer through the peritoneum instead of the tail vein allows obtaining a good perfusion. injecting the radiotracer through the peritoneum instead of the tail vein allows obtaining a good perfusion. References References [1] A. Costantinesco et al. SPECT, JNM 2005; 46:1005-1011[2] F. Garibaldi et al., Assessment of left ventricular [1] A. Costantinesco et al. SPECT, JNM 2005; 46:1005-1011[2] F. Garibaldi et al., Assessment of left ventricular perfusion by intraperitoneal administration of perfusion by intraperitoneal administration of 99mTc-MiBIc using high-resolution, high efficiency single photon detector 99mTc-MiBIc using high-resolution, high efficiency single photon detector to be to be submitted to EJNM)[3] P. Musico et al. M05-331: "A powerful readout system for high resolution and high efficiency molecular submitted to EJNM)[3] P. Musico et al. M05-331: "A powerful readout system for high resolution and high efficiency molecular a b c

description

High Resolution and High Efficiency Open SPECT Detector for Molecular Imaging Studies of Cardiovascular Diseases on Mice. 1.3 mm. 0.8 mm. 1.2 mm. 0.9 mm. 1.1 mm. 1.0 mm. Spine. Liver. - PowerPoint PPT Presentation

Transcript of MIOCARDIAL PERFUSION MEASUREMENTS WITH DIFFERENT ROUTES OF DELIVERY

Page 1: MIOCARDIAL PERFUSION MEASUREMENTS WITH DIFFERENT  ROUTES OF  DELIVERY

High Resolution and High Efficiency Open SPECT Detector forHigh Resolution and High Efficiency Open SPECT Detector for

Molecular Imaging Studies of Cardiovascular Diseases on MiceMolecular Imaging Studies of Cardiovascular Diseases on Mice

MIOCARDIAL PERFUSION MEASUREMENTS WITH DIFFERENT ROUTES OF DELIVERY

Pin Hole: 0.5 mmScintillator: NaI(Tl), 1.5 pitch mm thickPhotodetector: H8500 (2×2)Rt ~ 0.8 mm, En. Res. 14%Eff ~ 0.5 cps/μCi M ~ 3, FoV ~ 33 mm

DETECTOR PROTOTYPE

0.8 mm capillaries are clearly separated on image. CONCLUSIONS and OUTLOOK

Spine

Liver

Sistem Requirement:

Overall Resolution ~ 0.8 mm

Sensitivity ~ 10 cps/μCi (allowing dynamic studies and Thomographic acquisition ≤ 1 hour)

Field of View ~ 25 × 25 mm2 (mouse thoracic area dimension)

Acute myocardial infarction (AMI or MI), more commonly known as a heart attack, occurs when the blood supply to a part of the heart is interrupted. The resulting ischemia or oxygen shortage causes damage and potential death of heart tissue.

Diagram of a myocardial infarction (2) of the tip of the anterior wall of the heart (an apical infarct) after occlusion (1) of a branch of the left coronary artery (LCA, right coronary artery = RCA).

Small Animal SPECT Imaging (mice) allows:

• Direct monitoring of the dynamics of the infused cells;

• In vivo monitoring of disease/teraphy efficacy;

• Translational studies

SMALL ANIMAL IMAGING IN MIOCARDIAL INFARCTION THERAPHY

IMPROVE RESOLUTION• Gated Image

Heart Rate and Volume Change affect Image Quality;• Intrinsic Resolution

Sub-millimetre Intrinsic resolution could be achieved with: Rugged Scintillator Material CsI(Na), CsI(Tl), pixel of 0.5∻0.8

mm are available; LaBr3(Ce) Continuous, resolution of 0.5∻0.8 mm are

obtainable depending on design. This would solve the possible problems in dead arera between PSPMT’s

IMPROVE EFFICIENCY• Multi Pinhole Collimation

A factor 2∻4 (depends on design)• Increase Number of Detector Heads

A factor 4∻8 (depends on mechanical constraint)• Combine Reconstruction from Different Sets of Projections

A factor 4∻8 (depends on Number of Detector Heads)

MOVE TO MULTIMODAL APPROACHOpen System Could Be Used in Conjunction with: Optical Detector (high sensitivity) MRI (anatomical high resolution Information)

to get morphological as well functional features.Magnetic field requires new photodetector technology (SiPM)

   

Post-infarction survival has improved in recent years but NONE of the therapies is able to reverse the destructive cascade that occurs after acute myocardial infarction and lead to heart failure.Right now the results of clinical trials are somewhat disappointing: PRECLINICAL INVESTIGATION NEEDED

to better understand basic mechanisms: Best cell to deliver Route of delivery Fate of stem cells Action mechanism

Fig. 3 Flood field (Co-57) and pixel identification of CsI(Na) 0.8 mm pitch (a), 0.6 mm pitc coupled to Fig. 3 Flood field (Co-57) and pixel identification of CsI(Na) 0.8 mm pitch (a), 0.6 mm pitc coupled to Hamamatsu H9500Hamamatsu H9500

Fig. 2. a) Charge sampling optimization. b) pixel identification for CsI(Na) 0.8 mm pitch coupled with H9500 Fig. 2. a) Charge sampling optimization. b) pixel identification for CsI(Na) 0.8 mm pitch coupled with H9500 Hamamatsu (3 x 3 mm2 anode pitch) and Burle MCP (1.6 x 1.6 mm2 pitch)Hamamatsu (3 x 3 mm2 anode pitch) and Burle MCP (1.6 x 1.6 mm2 pitch)

Fig. 1 Spatial resolution and efficiency for High Fig. 1 Spatial resolution and efficiency for High resolution based system and Anger camera based resolution based system and Anger camera based systemsystem

M. BaiocchiM. Baiocchi1)1), E. Cisbani, E. Cisbani1)1), F. Cusanno, F. Cusanno1)1), G. De Vincentis, G. De Vincentis3)3), , F. GaribaldiF. Garibaldi2)2), M.L. Magliozzi, M.L. Magliozzi1)1), S. Majewski, S. Majewski4)4), G. Marano, G. Marano1)1), P. Musico , P. Musico 5)5), M. Musumeci, M. Musumeci1)1), S. Torrioli, S. Torrioli1)1), B. Tsui, B. Tsui6)6), , L. VitelliL. Vitelli1)1)1)1) I.S.S. ROMA (I); I.S.S. ROMA (I); 2)2) INFN ROMA1, Roma(I), INFN ROMA1, Roma(I), 3)3) University La Sapienza ROMA (I); University La Sapienza ROMA (I); 4)4) West Virginia University; West Virginia University; 5)5) I.N.F.N. Genova – via Dodecaneso, 33 – 16146 – GENOVA (I); I.N.F.N. Genova – via Dodecaneso, 33 – 16146 – GENOVA (I); 6)6) Johns Hopkins Johns Hopkins UniversityUniversitySPECT systems using pinhole apertures permit radiolabeled molecular distributions to be imaged in vivo in small animals. Nevertheless studying cardiovascular diseases by means of small animal SPECT systems using pinhole apertures permit radiolabeled molecular distributions to be imaged in vivo in small animals. Nevertheless studying cardiovascular diseases by means of small animal models is very challenging. Specifically, submillimeter spatial resolution, good energy resolution and high sensitivity are required. We designed what we consider the “optimal” radionuclide models is very challenging. Specifically, submillimeter spatial resolution, good energy resolution and high sensitivity are required. We designed what we consider the “optimal” radionuclide detector system for this task. It should allow studying both detection of unstable atherosclerotic plaques and monitoring the effect of therapy. The ideal system for these very challenging tasks detector system for this task. It should allow studying both detection of unstable atherosclerotic plaques and monitoring the effect of therapy. The ideal system for these very challenging tasks should be an “open” and flexible one, to be integrated in multimodality with other detectors (MRI, optical). This is not possible with the system based on Anger Camera. A dedicated high should be an “open” and flexible one, to be integrated in multimodality with other detectors (MRI, optical). This is not possible with the system based on Anger Camera. A dedicated high resolution detector is needed. Simulations and basic measurements have been performed with CsI(Na) scintillator arrays. Moreover, in order to understand the spatial resolution and sensitivity resolution detector is needed. Simulations and basic measurements have been performed with CsI(Na) scintillator arrays. Moreover, in order to understand the spatial resolution and sensitivity needso=f and solving practical probems (route of delivery of the radiotracer) measurements have been performed both on phantoms and mice.needso=f and solving practical probems (route of delivery of the radiotracer) measurements have been performed both on phantoms and mice.

aa

bb

We designed what we consider the “optimal” radionuclide detector system for this task, flexible enough to be integrated in a multimodality system: 8 detectors to optimize the trade-off between We designed what we consider the “optimal” radionuclide detector system for this task, flexible enough to be integrated in a multimodality system: 8 detectors to optimize the trade-off between spatial resolution and sensitivity. One of these special modules is a detector with spatial resolution in the range of 300-500 μm,sensitivity of 0.3 cps/kBq, and active area 100 x 100 mm2, using spatial resolution and sensitivity. One of these special modules is a detector with spatial resolution in the range of 300-500 μm,sensitivity of 0.3 cps/kBq, and active area 100 x 100 mm2, using tungsten pinhole collimator(s) and a high granularity scintillator (CsI(Na) with 0.8 mm pitch (the smallest so far achieved for SPECT detectors) or continuous LaBr3(Ce). The reasons for the choice tungsten pinhole collimator(s) and a high granularity scintillator (CsI(Na) with 0.8 mm pitch (the smallest so far achieved for SPECT detectors) or continuous LaBr3(Ce). The reasons for the choice of the layout comes from the fact that in the SPECT with multipinholes, with 3D reconstruction, a sufficient number of “resolution elements” has to be used. This translates in the need of 100-120 of the layout comes from the fact that in the SPECT with multipinholes, with 3D reconstruction, a sufficient number of “resolution elements” has to be used. This translates in the need of 100-120 pixels in 100 mm, that means an intrinsic spatial resolution of ri = 0.8 mm – 1 mm. Scintillator arrays of very small pixels have to be used and identifying so small pixels is challenging. It will pixels in 100 mm, that means an intrinsic spatial resolution of ri = 0.8 mm – 1 mm. Scintillator arrays of very small pixels have to be used and identifying so small pixels is challenging. It will require to fully exploit the characteristics of the electronics we built, capable of reading out up to ~ 4096 channels individually at 20 KHz [3]. Fig. 1 shows the advantages of the high resolution require to fully exploit the characteristics of the electronics we built, capable of reading out up to ~ 4096 channels individually at 20 KHz [3]. Fig. 1 shows the advantages of the high resolution dedicated detectors with respect to Anger camera based systems. Fig. 2 shows that CsI(Na) scintillator, 0.8 mm pitch can be used if coupled to Hamamatsu H9500 PSPMT (3 x 3 mm2 pitch), but dedicated detectors with respect to Anger camera based systems. Fig. 2 shows that CsI(Na) scintillator, 0.8 mm pitch can be used if coupled to Hamamatsu H9500 PSPMT (3 x 3 mm2 pitch), but sampling the light with smaller anode pixel size improves the pixel identification. Nevertheless some problem arise in the dead area between the PSPMT’s. Continuous LaBr3(Ce) could solve the sampling the light with smaller anode pixel size improves the pixel identification. Nevertheless some problem arise in the dead area between the PSPMT’s. Continuous LaBr3(Ce) could solve the problem of dead area. Fig. 3 shows the measurements results that validate the simulation. problem of dead area. Fig. 3 shows the measurements results that validate the simulation.

The assessment of myocardial perfusion plays an important role in the diagnosys and in guiding therapy. In order to determine the spatial resolution,sensitivity and energy The assessment of myocardial perfusion plays an important role in the diagnosys and in guiding therapy. In order to determine the spatial resolution,sensitivity and energy resolution needed for this task as well as to study animal handling issues we used a single head high-resolution detector prototype, having performances close to the resolution needed for this task as well as to study animal handling issues we used a single head high-resolution detector prototype, having performances close to the requested ones (NaI(Tl) 1.5 mm pitch 100 x 100 mm2, coupled to PSPMT Hamamatsu H8500 (see Fig. 4)). The performances are shown in Fig. 4. This detector allowed requested ones (NaI(Tl) 1.5 mm pitch 100 x 100 mm2, coupled to PSPMT Hamamatsu H8500 (see Fig. 4)). The performances are shown in Fig. 4. This detector allowed performing important perfusion measurement in mice, using differ routes of delivery. In fact using mice is particularly challenging in situations that require several performing important perfusion measurement in mice, using differ routes of delivery. In fact using mice is particularly challenging in situations that require several intravenous injections of radiotracers, possibly for week or even months, in chronically ill animal. This study has evaluated the feasibility of assessing left ventricular intravenous injections of radiotracers, possibly for week or even months, in chronically ill animal. This study has evaluated the feasibility of assessing left ventricular perfusion by intraperitoneal delivering of MIBI-Tc in healthy mice. In Fig. 5 a we show images of the mouse-injected trough the tail vein; transverse, sagittal and coronal perfusion by intraperitoneal delivering of MIBI-Tc in healthy mice. In Fig. 5 a we show images of the mouse-injected trough the tail vein; transverse, sagittal and coronal views are shown. The other mouse (Fig 5 b had the radiotracer injected peritoneally. The procedures were the same. The result shows that injecting the radiotracer through views are shown. The other mouse (Fig 5 b had the radiotracer injected peritoneally. The procedures were the same. The result shows that injecting the radiotracer through the peritoneum instead of the tail vein allows obtaining a good perfusion. The price to be payed is a reduction of the uptake by the heart. The sensitivity of the system has the peritoneum instead of the tail vein allows obtaining a good perfusion. The price to be payed is a reduction of the uptake by the heart. The sensitivity of the system has to be increased to compensate the reduction. This can be obtained by fine-tuning the parameters (the hole dimension and the magnification), using the multipinhole to be increased to compensate the reduction. This can be obtained by fine-tuning the parameters (the hole dimension and the magnification), using the multipinhole technique and adding as many detectors as possible to the system. technique and adding as many detectors as possible to the system.

Transverse, sagittal and Transverse, sagittal and coronal heart views. Tail vein coronal heart views. Tail vein injectioninjection

Transverse, sagittal and Transverse, sagittal and coronal heart views. Peritoneal coronal heart views. Peritoneal injectioninjection

1.3 mm

1.2 mm

1.1 mm

1.0 mm

0.9 mm

0.8 mm

This paper describes the research started by our collaboration in outlining the best detectors suited for cardiovascular diseases study on mice and the preliminary This paper describes the research started by our collaboration in outlining the best detectors suited for cardiovascular diseases study on mice and the preliminary perfusion measurements, with an high resolution detector prototype, comparing the uptake of Tc-MIBI with the two modalities: tail vein and peritoneum.perfusion measurements, with an high resolution detector prototype, comparing the uptake of Tc-MIBI with the two modalities: tail vein and peritoneum. The spatial The spatial resolution of the prototype showed to be sufficient for perfusion studies. The energy resolution allows using dual tracers techniquesresolution of the prototype showed to be sufficient for perfusion studies. The energy resolution allows using dual tracers techniques . We demonstrated that injecting the . We demonstrated that injecting the radiotracer through the peritoneum instead of the tail vein allows obtaining a good perfusion. radiotracer through the peritoneum instead of the tail vein allows obtaining a good perfusion.

ReferencesReferences [1] A. Costantinesco et al. SPECT, JNM 2005; 46:1005-1011[2] F. Garibaldi et al., Assessment of left ventricular perfusion by intraperitoneal [1] A. Costantinesco et al. SPECT, JNM 2005; 46:1005-1011[2] F. Garibaldi et al., Assessment of left ventricular perfusion by intraperitoneal administration of administration of 99mTc-MiBIc using high-resolution, high efficiency single photon detector 99mTc-MiBIc using high-resolution, high efficiency single photon detector to be submitted to EJNM)[3] P. Musico et al. M05-331: "A powerful readout to be submitted to EJNM)[3] P. Musico et al. M05-331: "A powerful readout

system for high resolution and high efficiency molecular imaging studies of cardiovascular diseases in mice". .system for high resolution and high efficiency molecular imaging studies of cardiovascular diseases in mice". .

a b c