The Experts below are selected from a list of 1338 Experts worldwide ranked by ideXlab platform
Marie Foley Kijewski - One of the best experts on this subject based on the ideXlab platform.
-
performance of a high sensitivity dedicated cardiac SPECT Scanner for striatal uptake quantification in the brain based on analysis of projection data
Medical Physics, 2013Co-Authors: Mi-ae Park, Stephen C. Moore, Stefan Müller, Sarah J. Mcquaid, Marie Foley KijewskiAbstract:Purpose: The authors have previously reported the advantages of high-sensitivity single-photon emission computed tomography (SPECT) systems for imaging structures located deep inside the brain. DaTscan (Isoflupane I-123) is a dopamine transporter (DaT) imaging agent that has shown potential for early detection of Parkinson disease (PD), as well as for monitoring progression of the disease. Realizing the full potential of DaTscan requires efficient estimation of striatal uptake from SPECT images. They have evaluated two SPECT systems, a conventional dual-head gamma camera with low-energy high-resolution collimators (conventional) and a dedicated high-sensitivity multidetector cardiac imaging system (dedicated) for imaging tasks related to PD. Methods: Cramer–Rao bounds (CRB) on precision of estimates of striatal and background activity concentrations were calculated from high-count, separate acquisitions of the compartments (right striata, left striata, background) of a striatal phantom. CRB on striatal and background activity concentration were calculated from essentially noise-free projection datasets, synthesized by scaling and summing the compartment projection datasets, for a range of total detected counts. They also calculated variances of estimates of specific-to-nonspecific binding ratios (BR) and asymmetry indices from these values using propagation of error analysis, as well as the precision of measuring changes in BR on the order of the average annual decline in early PD. Results: Under typical clinical conditions, the conventional camera detected 2 M counts while the dedicated camera detected 12 M counts. Assuming a normal BR of 5, the standard deviation of BR estimates was 0.042 and 0.021 for the conventional and dedicated system, reSPECTively. For an 8% decrease to BR = 4.6, the signal-to-noise ratio were 6.8 (conventional) and 13.3 (dedicated); for a 5% decrease, they were 4.2 (conventional) and 8.3 (dedicated). Conclusions: This implies that PD can be detected earlier with the dedicated system than with the conventional system; therefore, earlier identification of PD progression should be possible with the high-sensitivity dedicated SPECT camera.
-
Performance of a high‐sensitivity dedicated cardiac SPECT Scanner for striatal uptake quantification in the brain based on analysis of projection data
Medical physics, 2013Co-Authors: Mi-ae Park, Stephen C. Moore, Stefan Müller, Sarah J. Mcquaid, Marie Foley KijewskiAbstract:Purpose: The authors have previously reported the advantages of high-sensitivity single-photon emission computed tomography (SPECT) systems for imaging structures located deep inside the brain. DaTscan (Isoflupane I-123) is a dopamine transporter (DaT) imaging agent that has shown potential for early detection of Parkinson disease (PD), as well as for monitoring progression of the disease. Realizing the full potential of DaTscan requires efficient estimation of striatal uptake from SPECT images. They have evaluated two SPECT systems, a conventional dual-head gamma camera with low-energy high-resolution collimators (conventional) and a dedicated high-sensitivity multidetector cardiac imaging system (dedicated) for imaging tasks related to PD. Methods: Cramer–Rao bounds (CRB) on precision of estimates of striatal and background activity concentrations were calculated from high-count, separate acquisitions of the compartments (right striata, left striata, background) of a striatal phantom. CRB on striatal and background activity concentration were calculated from essentially noise-free projection datasets, synthesized by scaling and summing the compartment projection datasets, for a range of total detected counts. They also calculated variances of estimates of specific-to-nonspecific binding ratios (BR) and asymmetry indices from these values using propagation of error analysis, as well as the precision of measuring changes in BR on the order of the average annual decline in early PD. Results: Under typical clinical conditions, the conventional camera detected 2 M counts while the dedicated camera detected 12 M counts. Assuming a normal BR of 5, the standard deviation of BR estimates was 0.042 and 0.021 for the conventional and dedicated system, reSPECTively. For an 8% decrease to BR = 4.6, the signal-to-noise ratio were 6.8 (conventional) and 13.3 (dedicated); for a 5% decrease, they were 4.2 (conventional) and 8.3 (dedicated). Conclusions: This implies that PD can be detected earlier with the dedicated system than with the conventional system; therefore, earlier identification of PD progression should be possible with the high-sensitivity dedicated SPECT camera.
Hirofumi Fujii - One of the best experts on this subject based on the ideXlab platform.
-
Abstract 4325: The requisites forin vivoclear visualization of intratumoral heterogeneity by a SPECT/CT Scanner dedicated for small animal imaging
Tumor Biology, 2010Co-Authors: Izumi O Umeda, Yasushi Arano, Kotaro Tani, Keisuke Tsuda, Mayumi Ogata, Kunikazu Moribe, Masayuki Yamaguchi, Hirofumi FujiiAbstract:Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC Objectives: Although even conventional nuclear medicine tests could successfully detect tumor masses in vivo, they did not always visualize heterogeneous interiors of tumor masses. The clear visualization of intratumoral heterogeneity in vivo will give us additional information about the choice of cancer therapy. Recently developed single photon emission computed tomography (SPECT) Scanners dedicated for small animal imaging show excellent spatial resolution (< 1 mm) and they are expected to visualize intratumoral heterogeneity in vivo even for mouse tumors. But, little studies have revealed the requisites for this purpose. In this study, we considered the conditions to image intratumoral heterogeneity in vivo. Materials and Methods: A small animal SPECT/CT Scanner with four detectors equipped with 9-pinhole collimators (1.0 mm or 1.4 mm of pinholes, Bioscan, Washington, D.C.) was used. First, phantom experiments with 111In of similar radioactivity that is commonly used in mouse imaging studies were performed to evaluate the optimal conditions to obtain best spatial resolution and concentration linearity. Then, mouse tumors were imaged. 111In-labeled liposomes with high specific activity and high concentration were injected to Sarcoma180 bearing ddY mice. In vivo SPECT images and ex vivo autoradiograms were compared and the radioactivity distribution in tumors and other tissues was measured. Results: In phantom experiments with 111In, the best spatial resolution under the current experimental conditions simulating in vivo small animal imaging was 1.1 mm (1.4 mmϕ, 5 MBq/mL, 120 min of total acquisition), although they greatly depended on total acquisition counts or total radioactivity. The good linearity between the concentration and SPECT values was obtained under the condition of 0.5-1.5 MBq/mL. 111In-labeled liposomes (15-20 MBq/mouse) were strongly accumulated in the tumor (1-2 MBq/g, 10-15% of injected dose/g), predominantly in the marginal regions of tumors. And, SPECT clearly visualized this heterogeneous intratumoral localization in vivo with good spatial resolution with the acquisition time of 60 min at 24h after the injection. The threshold to clearly visualize the tumor heterogeneity was about 0.5 MBq/g. Ex vivo autoradiograms of excised tumors demonstrated that the small animal SPECT Scanner could successfully image the heterogeneous intratumoral accumulation of liposomes. Conclusion: The SPECT/CT Scanner dedicated for small animal imaging successfully visualized the tumor heterogeneity in vivo using radioactive probes with rather high specific radioactivity and high concentration. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4325.
-
abstract 4325 the requisites forin vivoclear visualization of intratumoral heterogeneity by a SPECT ct Scanner dedicated for small animal imaging
Cancer Research, 2010Co-Authors: Izumi O Umeda, Yasushi Arano, Kotaro Tani, Keisuke Tsuda, Mayumi Ogata, Kunikazu Moribe, Masayuki Yamaguchi, Hirofumi FujiiAbstract:Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC Objectives: Although even conventional nuclear medicine tests could successfully detect tumor masses in vivo, they did not always visualize heterogeneous interiors of tumor masses. The clear visualization of intratumoral heterogeneity in vivo will give us additional information about the choice of cancer therapy. Recently developed single photon emission computed tomography (SPECT) Scanners dedicated for small animal imaging show excellent spatial resolution (< 1 mm) and they are expected to visualize intratumoral heterogeneity in vivo even for mouse tumors. But, little studies have revealed the requisites for this purpose. In this study, we considered the conditions to image intratumoral heterogeneity in vivo. Materials and Methods: A small animal SPECT/CT Scanner with four detectors equipped with 9-pinhole collimators (1.0 mm or 1.4 mm of pinholes, Bioscan, Washington, D.C.) was used. First, phantom experiments with 111In of similar radioactivity that is commonly used in mouse imaging studies were performed to evaluate the optimal conditions to obtain best spatial resolution and concentration linearity. Then, mouse tumors were imaged. 111In-labeled liposomes with high specific activity and high concentration were injected to Sarcoma180 bearing ddY mice. In vivo SPECT images and ex vivo autoradiograms were compared and the radioactivity distribution in tumors and other tissues was measured. Results: In phantom experiments with 111In, the best spatial resolution under the current experimental conditions simulating in vivo small animal imaging was 1.1 mm (1.4 mmϕ, 5 MBq/mL, 120 min of total acquisition), although they greatly depended on total acquisition counts or total radioactivity. The good linearity between the concentration and SPECT values was obtained under the condition of 0.5-1.5 MBq/mL. 111In-labeled liposomes (15-20 MBq/mouse) were strongly accumulated in the tumor (1-2 MBq/g, 10-15% of injected dose/g), predominantly in the marginal regions of tumors. And, SPECT clearly visualized this heterogeneous intratumoral localization in vivo with good spatial resolution with the acquisition time of 60 min at 24h after the injection. The threshold to clearly visualize the tumor heterogeneity was about 0.5 MBq/g. Ex vivo autoradiograms of excised tumors demonstrated that the small animal SPECT Scanner could successfully image the heterogeneous intratumoral accumulation of liposomes. Conclusion: The SPECT/CT Scanner dedicated for small animal imaging successfully visualized the tumor heterogeneity in vivo using radioactive probes with rather high specific radioactivity and high concentration. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4325.
Izumi O Umeda - One of the best experts on this subject based on the ideXlab platform.
-
high resolution SPECT imaging for visualization of intratumoral heterogeneity using a SPECT ct Scanner dedicated for small animal imaging
Annals of Nuclear Medicine, 2012Co-Authors: Izumi O Umeda, Kotaro Tani, Keisuke Tsuda, Masamitsu Kobayashi, Mayumi Ogata, Sadaaki Kimura, Mitsuyoshi Yoshimoto, Shuji Kojima, Kunikazu Moribe, Keiji YamamotoAbstract:Objectives Tumor interiors are never homogeneous and in vivo visualization of intratumoral heterogeneity would be an innovation that contributes to improved cancer therapy. But, conventional nuclear medicine tests have failed to visualize heterogeneity in vivo because of limited spatial resolution. Recently developed single photon emission computed tomographic (SPECT) Scanners dedicated for small animal imaging are of interest due to their excellent spatial resolution of <1 mm, but few studies have focused on the evaluation of intratumoral heterogeneity. We investigated the optimal conditions related to high resolution imaging of heterogeneous tumor interiors using a small animal SPECT Scanner.
-
Abstract 4325: The requisites forin vivoclear visualization of intratumoral heterogeneity by a SPECT/CT Scanner dedicated for small animal imaging
Tumor Biology, 2010Co-Authors: Izumi O Umeda, Yasushi Arano, Kotaro Tani, Keisuke Tsuda, Mayumi Ogata, Kunikazu Moribe, Masayuki Yamaguchi, Hirofumi FujiiAbstract:Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC Objectives: Although even conventional nuclear medicine tests could successfully detect tumor masses in vivo, they did not always visualize heterogeneous interiors of tumor masses. The clear visualization of intratumoral heterogeneity in vivo will give us additional information about the choice of cancer therapy. Recently developed single photon emission computed tomography (SPECT) Scanners dedicated for small animal imaging show excellent spatial resolution (< 1 mm) and they are expected to visualize intratumoral heterogeneity in vivo even for mouse tumors. But, little studies have revealed the requisites for this purpose. In this study, we considered the conditions to image intratumoral heterogeneity in vivo. Materials and Methods: A small animal SPECT/CT Scanner with four detectors equipped with 9-pinhole collimators (1.0 mm or 1.4 mm of pinholes, Bioscan, Washington, D.C.) was used. First, phantom experiments with 111In of similar radioactivity that is commonly used in mouse imaging studies were performed to evaluate the optimal conditions to obtain best spatial resolution and concentration linearity. Then, mouse tumors were imaged. 111In-labeled liposomes with high specific activity and high concentration were injected to Sarcoma180 bearing ddY mice. In vivo SPECT images and ex vivo autoradiograms were compared and the radioactivity distribution in tumors and other tissues was measured. Results: In phantom experiments with 111In, the best spatial resolution under the current experimental conditions simulating in vivo small animal imaging was 1.1 mm (1.4 mmϕ, 5 MBq/mL, 120 min of total acquisition), although they greatly depended on total acquisition counts or total radioactivity. The good linearity between the concentration and SPECT values was obtained under the condition of 0.5-1.5 MBq/mL. 111In-labeled liposomes (15-20 MBq/mouse) were strongly accumulated in the tumor (1-2 MBq/g, 10-15% of injected dose/g), predominantly in the marginal regions of tumors. And, SPECT clearly visualized this heterogeneous intratumoral localization in vivo with good spatial resolution with the acquisition time of 60 min at 24h after the injection. The threshold to clearly visualize the tumor heterogeneity was about 0.5 MBq/g. Ex vivo autoradiograms of excised tumors demonstrated that the small animal SPECT Scanner could successfully image the heterogeneous intratumoral accumulation of liposomes. Conclusion: The SPECT/CT Scanner dedicated for small animal imaging successfully visualized the tumor heterogeneity in vivo using radioactive probes with rather high specific radioactivity and high concentration. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4325.
-
abstract 4325 the requisites forin vivoclear visualization of intratumoral heterogeneity by a SPECT ct Scanner dedicated for small animal imaging
Cancer Research, 2010Co-Authors: Izumi O Umeda, Yasushi Arano, Kotaro Tani, Keisuke Tsuda, Mayumi Ogata, Kunikazu Moribe, Masayuki Yamaguchi, Hirofumi FujiiAbstract:Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC Objectives: Although even conventional nuclear medicine tests could successfully detect tumor masses in vivo, they did not always visualize heterogeneous interiors of tumor masses. The clear visualization of intratumoral heterogeneity in vivo will give us additional information about the choice of cancer therapy. Recently developed single photon emission computed tomography (SPECT) Scanners dedicated for small animal imaging show excellent spatial resolution (< 1 mm) and they are expected to visualize intratumoral heterogeneity in vivo even for mouse tumors. But, little studies have revealed the requisites for this purpose. In this study, we considered the conditions to image intratumoral heterogeneity in vivo. Materials and Methods: A small animal SPECT/CT Scanner with four detectors equipped with 9-pinhole collimators (1.0 mm or 1.4 mm of pinholes, Bioscan, Washington, D.C.) was used. First, phantom experiments with 111In of similar radioactivity that is commonly used in mouse imaging studies were performed to evaluate the optimal conditions to obtain best spatial resolution and concentration linearity. Then, mouse tumors were imaged. 111In-labeled liposomes with high specific activity and high concentration were injected to Sarcoma180 bearing ddY mice. In vivo SPECT images and ex vivo autoradiograms were compared and the radioactivity distribution in tumors and other tissues was measured. Results: In phantom experiments with 111In, the best spatial resolution under the current experimental conditions simulating in vivo small animal imaging was 1.1 mm (1.4 mmϕ, 5 MBq/mL, 120 min of total acquisition), although they greatly depended on total acquisition counts or total radioactivity. The good linearity between the concentration and SPECT values was obtained under the condition of 0.5-1.5 MBq/mL. 111In-labeled liposomes (15-20 MBq/mouse) were strongly accumulated in the tumor (1-2 MBq/g, 10-15% of injected dose/g), predominantly in the marginal regions of tumors. And, SPECT clearly visualized this heterogeneous intratumoral localization in vivo with good spatial resolution with the acquisition time of 60 min at 24h after the injection. The threshold to clearly visualize the tumor heterogeneity was about 0.5 MBq/g. Ex vivo autoradiograms of excised tumors demonstrated that the small animal SPECT Scanner could successfully image the heterogeneous intratumoral accumulation of liposomes. Conclusion: The SPECT/CT Scanner dedicated for small animal imaging successfully visualized the tumor heterogeneity in vivo using radioactive probes with rather high specific radioactivity and high concentration. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4325.
Rolf Clackdoyle - One of the best experts on this subject based on the ideXlab platform.
-
Exact inversion of the exponential x-ray transform for rotating slant-hole (RSH) SPECT.
Physics in medicine and biology, 2002Co-Authors: Jean-marc Wagner, Frédéric Noo, Rolf ClackdoyleAbstract:The RSH SPECT Scanner provides parallel-beam attenuated projections for a fully 3D acquisition geometry. The geometry can be represented by circles on the unit sphere of projection directions, one circle for each position of the detector head. Unlike most other fully 3D geometries this one is particularly challenging because there are no 2D subsets in the data. When no attenuation is present, it is well known that an unmeasured projection can be synthesized if it lies inside one of the measured circles. The main result of this work is that under some assumptions on the attenuation distribution, attenuated projections within a circle can be synthesized from available attenuated projections. One consequence is that RSH SPECT projections can be rebinned into a conventional SPECT geometry for which analytic attenuation correction techniques are available.
-
Dynamic cardiac SPECT imaging using a stationary SPECT camera
IEEE Symposium Conference Record Nuclear Science 2004., 1Co-Authors: R. Maddula, Rolf Clackdoyle, John A. Roberts, E.v.r. Di BellaAbstract:The current SPECT scanning paradigm involves slow rotation of multiple detectors around the patient, and is not well adapted to performing multiple collections of tomographically complete data over short time intervals. In order to rotate the detectors fast around the patient, the detectors of the current SPECT Scanner are made to rotate in a circular path resulting increase in the distance of detectors from the patient and a decrease in spatial resolution. We are investigating a novel SPECT camera with the capability to collect full tomographic data every 2 seconds. The proposed camera uses three stationary detectors mounted with slant-hole collimators that rotate at about 30 rpm. Because the detectors are stationary, they can be placed much closer to the patient for improved spatial resolution. With Monte Carlo simulations and list-mode reconstructions, we compared the performance of conventional 3-headed SPECT with the proposed stationary SPECT system to estimate the kinetic parameters of two-compartmental model of myocardial perfusion. The study separated the effects of fast temporal scanning speed and better spatial resolution of DyRoSH Scanner in estimating the kinetic parameters of myocardial perfusion accurately. The proposed system showed better accuracy in estimating kinetic parameters compared to conventional SPECT Scanner.
Paolo Russo - One of the best experts on this subject based on the ideXlab platform.
-
solid state detectors for small animal imaging
2014Co-Authors: Paolo Russo, Alberto Del GuerraAbstract:Semiconductor detector technology, initially developed for high energy physics applications, has found a distinctive role in high performance systems for X-ray and gamma-ray medical imaging applications, including small animal imaging. Single-Photon Emission Computed Tomography (SPECT) small animal imaging requires the development of compact detectors with intrinsically ultrahigh spatial resolution, high energy resolution and good detection efficiency, in addition to suitable radiation collimation strategies. This overall performance can only partly be guaranteed by scintillator based systems with photomultiplier tube readout, the most used technology at present for small animal SPECT Scanners. On the other hand, with reSPECT to scintillator based detectors, semiconductor detectors can offer a gain by approximately a factor two in energy resolution at typical radionuclide energies, a factor greater than two in intrinsic spatial resolution, and a comparable intrinsic detection efficiency, though usually at a reduced field of view. Moreover, their compactness could be crucial in devising animal “personalized” miniature Scanners. An additional interesting feature of semiconductor based small animal SPECT Scanners is that the detector technology can be used both for gamma-ray imaging and for X-ray imaging, when coupling the SPECT Scanner to a low resolution X-ray CT Scanner for anatomical registration. The requirement of high spatial resolution, coupled to high sensitivity, becomes also stringent in microPET systems, where semiconductor detectors could be the technology of choice for future high performance PET Scanners.
-
high resolution 125 i pinhole SPECT imaging of the mouse thyroid with the mediSPECT small animal cdte Scanner
IEEE Transactions on Nuclear Science, 2010Co-Authors: Giovanni Mettivier, Maria Cristina Montesi, Assunta Simona Curion, Adele Lauria, M Marotta, Paolo RussoAbstract:The first in vivo tomographic 125I imaging of the mouse thyroid carried out with the new MediSPECT small animal SPECT Scanner is presented. The Scanner is based on a fine pitch CdTe semiconductor pixel detector (14 × 14 mm2, 256 × 256 square pixel with a 55 m side) and equipped with a set of high resolution collimators. The collimation and detection units of the Scanner are mounted on a gantry, rotating around a horizontal axis, along which is placed the small animal housing. In an in vivo test, the mouse was injected with a Na125 I solution having a total activity of 31.8 MBq. The planar projections for SPECT reconstruction were acquired with a 300 m pinhole (magnification 1.47 and field of view of 9.6 × 9.6 mm2). The projections were captured in a step-and-shoot fashion and were processed with an Ordered Subsets-Expectation Maximization reconstruction algorithm in order to obtain the SPECT images. Several 125I imaging tests have been made by using phantoms to assess the detector spatial resolution. The measured spatial resolution with a 300 m pinhole is about 0.5 mm in planar imaging and better than 1 mm in tomographic imaging.
-
High Resolution ${}^{125}$ I Pinhole SPECT Imaging of the Mouse Thyroid With the MediSPECT Small Animal CdTe Scanner
IEEE Transactions on Nuclear Science, 2010Co-Authors: Giovanni Mettivier, Maria Cristina Montesi, Assunta Simona Curion, Adele Lauria, Marotta M, Paolo RussoAbstract:The first in vivo tomographic 125I imaging of the mouse thyroid carried out with the new MediSPECT small animal SPECT Scanner is presented. The Scanner is based on a fine pitch CdTe semiconductor pixel detector (14 × 14 mm2, 256 × 256 square pixel with a 55 m side) and equipped with a set of high resolution collimators. The collimation and detection units of the Scanner are mounted on a gantry, rotating around a horizontal axis, along which is placed the small animal housing. In an in vivo test, the mouse was injected with a Na125 I solution having a total activity of 31.8 MBq. The planar projections for SPECT reconstruction were acquired with a 300 m pinhole (magnification 1.47 and field of view of 9.6 × 9.6 mm2). The projections were captured in a step-and-shoot fashion and were processed with an Ordered Subsets-Expectation Maximization reconstruction algorithm in order to obtain the SPECT images. Several 125I imaging tests have been made by using phantoms to assess the detector spatial resolution. The measured spatial resolution with a 300 m pinhole is about 0.5 mm in planar imaging and better than 1 mm in tomographic imaging.
-
high resolution 125 i pinhole SPECT imaging of the mouse thyroid with the mediSPECT small animal cdte Scanner
IEEE Nuclear Science Symposium, 2008Co-Authors: Giovanni Mettivier, Maria Cristina Montesi, Adele Lauria, Paolo RussoAbstract:We present first in vivo tomographic Na125I imaging of the mouse thyroid carried out with the new MediSPECT small animal SPECT Scanner, based on a fine pitch CdTe pixel detector (14×14 mm2, 256×256 square pixel of 55 μm side) and equipped with a high resolution collimators set. The MediSPECT Scanner is based on a gantry, hosting the collimation and detection units, rotating around a horizontal axis along which is the small animal housing. The mouse was injected with a Na125I solution with a total activity of 31.8 MBq. The planar projections for SPECT reconstruction were acquired with a 300 μm tungsten pinhole (magnification 1.47 and a Field of View — FoV - of 9.6×9.6 mm2). The projections have been captured in a step-and shoot fashion by rotating the detector around the animal holder. To obtain the SPECT image all the projections are elaborated with a C++ software based on ordered subsets-expectation maximization (OS-EM) reconstruction algorithm, developed by our group. Test images for assessing the MediSPECT Scanner spatial resolution have been also acquired using phantoms and are also presented in this wok. The measured spatial resolution with a 300 μm pinhole is, in planar imaging, about 500 μm and, in tomographic imaging, better than 900 μm. The modular structure of MediSPECT allows for multimodal imaging: at present, a Fluorescence Reflectance Imaging head has been installed, for planar optical imaging in addition to SPECT imaging.