Felicia Zito - Academia.edu (original) (raw)
Papers by Felicia Zito
Journal of Nuclear Medicine, 2003
The aim of this work is the presentation and comparison of state-of-the-art dedicated PET systems... more The aim of this work is the presentation and comparison of state-of-the-art dedicated PET systems actually available on the market, in terms of physical performance and technical features. Particular attention has been given to evaluate the whole-body performance by sensitivity, spatial resolution, dead time, noise equivalent counting rate (NECR), and scatter fraction. PET/CT systems were also included as new proposals to improve diagnostic accuracy of PET, allowing effective anatomic integration to functional data. An overview of actually implemented reconstruction algorithms is also reported to fully understand all of the factors that contribute to image quality.
Radiotherapy and Oncology, 2010
Journal of Nuclear Medicine
Minerva Anestesiologica
A copyedited and fully formatted version will be made available soon. The final version may conta... more A copyedited and fully formatted version will be made available soon. The final version may contain major or minor changes. Subscription: Information about subscribing to Minerva Medica journals is online at: http://www.minervamedica.it/en/how-to-order-journals.php Reprints and permissions: For information about reprints and permissions send an email to:
8.2 Transplantation
A copyedited and fully formatted version will be made available soon. The final version may conta... more A copyedited and fully formatted version will be made available soon. The final version may contain major or minor changes. Subscription: Information about subscribing to Minerva Medica journals is online at: http://www.minervamedica.it/en/how-to-order-journals.php Reprints and permissions: For information about reprints and permissions send an email to:
Medical physics, 2017
Design, realization, scan, and characterization of a phantom for PET Automatic Segmentation (PET-... more Design, realization, scan, and characterization of a phantom for PET Automatic Segmentation (PET-AS) assessment are presented. Radioactive zeolites immersed in a radioactive heterogeneous background simulate realistic wall-less lesions with known irregular shape and known homogeneous or heterogeneous internal activity. Three different zeolite families were evaluated in terms of radioactive uptake homogeneity, necessary to define activity and contour ground truth. Heterogeneous lesions were simulated by the perfect matching of two portions of a broken zeolite, soaked in two different (18) F-FDG radioactive solutions. Heterogeneous backgrounds were obtained with tissue paper balls and sponge pieces immersed into radioactive solutions. Natural clinoptilolite proved to be the most suitable zeolite for the construction of artificial objects mimicking homogeneous and heterogeneous uptakes in (18) F-FDG PET lesions. Heterogeneous backgrounds showed a coefficient of variation equal to 269% ...
Society of Nuclear Medicine Annual Meeting Abstracts, May 1, 2010
Cancer Research, Nov 1, 1991
We describe a method to postlabel, ¡nvivo, biotinylated monoclonal antibodies pretargeted onto t... more We describe a method to postlabel, ¡nvivo, biotinylated monoclonal antibodies pretargeted onto tumor deposits when most of the non-tumorbound antibodies have already been cleared as avidin-bound complexes. The application of this principle to tumor detection by immunoscintigraphy was tested in 20 patients with histológica!!}documented cancer and increased circulating carcinoembryonic antigen levels. One mg of biotinylated anti-carcinoembryonic antigen monoclonal antibody (FO23C5) was administered i.v. (first step). After 3 days, 4-6 mg of cold avidin were injected i.v. (second step), followed 48 h later by 0.2-0.3 mg of a biotin derivative labeled with '"In (2-3 mCi) (third step). No evidence of toxicity was observed. Whole body radioactivity distri bution was measured in five patients at various intervals postinjection by the conjugate counting technique. Tumors and métastases were detected in 18 of 19 patients (the remaining patient was a true negative) within 3 h after administration of '"In-biotin by planar or single photon emission tomography imaging. At the time of imaging, tumor/blood pool ratio was 5.5 ±3.2, and tumor/liver ratio was 6.7 ±3.9. Blood clearance of '"Inbiotin was multiexponential, with the fast component having a i. of 5 ± 3 min. Urinary excretion of radioactivity over 3 h was 63.5 ±4.9% of the injected dose. Radioactivity at 3 h was 6.5 ±1.8% in blood, 1.6 ± 0.3% in the kidney, and 2.4 ±0.6% in the liver. This approach represents an improvement in immunoscintigraphic techniques for tumor localization. The potential use for radioimmunotherapy is discussed.
Medical Physics, 2016
Quantitative (18)F-fluorodeoxyglucose positron emission tomography is limited by the uncertainty ... more Quantitative (18)F-fluorodeoxyglucose positron emission tomography is limited by the uncertainty in lesion delineation due to poor SNR, low resolution, and partial volume effects, subsequently impacting oncological assessment, treatment planning, and follow-up. The present work develops and validates a segmentation algorithm based on statistical clustering. The introduction of constraints based on background features and contiguity priors is expected to improve robustness vs clinical image characteristics such as lesion dimension, noise, and contrast level. An eight-class Gaussian mixture model (GMM) clustering algorithm was modified by constraining the mean and variance parameters of four background classes according to the previous analysis of a lesion-free background volume of interest (background modeling). Hence, expectation maximization operated only on the four classes dedicated to lesion detection. To favor the segmentation of connected objects, a further variant was introduced by inserting priors relevant to the classification of neighbors. The algorithm was applied to simulated datasets and acquired phantom data. Feasibility and robustness toward initialization were assessed on a clinical dataset manually contoured by two expert clinicians. Comparisons were performed with respect to a standard eight-class GMM algorithm and to four different state-of-the-art methods in terms of volume error (VE), Dice index, classification error (CE), and Hausdorff distance (HD). The proposed GMM segmentation with background modeling outperformed standard GMM and all the other tested methods. Medians of accuracy indexes were VE <3%, Dice >0.88, CE <0.25, and HD <1.2 in simulations; VE <23%, Dice >0.74, CE <0.43, and HD <1.77 in phantom data. Robustness toward image statistic changes (±15%) was shown by the low index changes: <26% for VE, <17% for Dice, and <15% for CE. Finally, robustness toward the user-dependent volume initialization was demonstrated. The inclusion of the spatial prior improved segmentation accuracy only for lesions surrounded by heterogeneous background: in the relevant simulation subset, the median VE significantly decreased from 13% to 7%. Results on clinical data were found in accordance with simulations, with absolute VE <7%, Dice >0.85, CE <0.30, and HD <0.81. The sole introduction of constraints based on background modeling outperformed standard GMM and the other tested algorithms. Insertion of a spatial prior improved the accuracy for realistic cases of objects in heterogeneous backgrounds. Moreover, robustness against initialization supports the applicability in a clinical setting. In conclusion, application-driven constraints can generally improve the capabilities of GMM and statistical clustering algorithms.
Society of Nuclear Medicine Annual Meeting Abstracts, May 1, 2009
Society of Nuclear Medicine Annual Meeting Abstracts, May 1, 2010
European Journal of Nuclear Medicine and Molecular Imaging, Apr 30, 1994
The physical performances of two current state-of-the-art scanners dedicated to functional imagin... more The physical performances of two current state-of-the-art scanners dedicated to functional imaging of the brain, one a single-photon emission tomography (SPET) scanner and the other a positron emission tomography (PET) scanner, have been compared under identical conditions. The aim of the study was to compare the capabilities of the devices under conditions resembling the routine clinical environment, as well as to consider other issues such as radiation burden for some common investigations. Both systems have slightly less than 11-cm axial fields of view. The PET system can be operated in a septa-less (3D) mode as well as conventionally with septa (2D). The spatial resolution of both devices was less than 8 mm in all dimensions in scattering media. On average, the PET scanner's resolution was approximately 10%-15% better than the SPET system. Energy resolution on the SPET system was superior due the scintillator used [NaI(T1)]. Sensitivity in air with a line source on the PET system was found to be-150 times greater in 3D and-25 times greater in 2D than with the SPET system. A normal subject was studied on each system in an attempt to obtain the highest quality data possible for a subjective comparison. It is clear that, while PET retains the advantages of more desirable radiopharmaceuticals and higher sensitivity, the quality obtainable from SPET devices has improved markedly. SPET may prove as useful for many clinical investigations.
Nuclear Instruments and Methods in Physics Research Section a Accelerators Spectrometers Detectors and Associated Equipment, Feb 1, 2007
The effect of malfunctioning detector blocks on accuracy of PET reconstructed images was evaluate... more The effect of malfunctioning detector blocks on accuracy of PET reconstructed images was evaluated qualitatively and quantitatively, by using the ECAT EXACT HR+ scanner. A procedure to simulate defective block was carried out after analyzing and comparing blank scans obtained with ...
![Research paper thumbnail of Lung inhomogeneities, inflation and [ 18 F]2-fluoro-2-deoxy-d-glucose uptake rate in acute respiratory distress syndrome](https://attachments.academia-assets.com/69306041/thumbnails/1.jpg)
](European Respiratory Journal, 2015
The aim of the study was to determine the size and location of homogeneous inflamed/noninflamed a... more The aim of the study was to determine the size and location of homogeneous inflamed/noninflamed and inhomogeneous inflamed/noninflamed lung compartments and their association with acute respiratory distress syndrome (ARDS) severity.In total, 20 ARDS patients underwent 5 and 45 cmH2O computed tomography (CT) scans to measure lung recruitability. [18F]2-fluoro-2-deoxy-d-glucose ([18F]FDG) uptake and lung inhomogeneities were quantified with a positron emission tomography-CT scan at 10 cmH2O. We defined four compartments with normal/abnormal [18F]FDG uptake and lung homogeneity.The homogeneous compartment with normal [18F]FDG uptake was primarily composed of well-inflated tissue (80±16%), double-sized in nondependent lung (32±27% versus 16±17%, p<0.0001) and decreased in size from mild, moderate to severe ARDS (33±14%, 26±20% and 5±9% of the total lung volume, respectively, p=0.05). The homogeneous compartment with high [18F]FDG uptake was similarly distributed between the dependent...
Proceedings of the 25th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (IEEE Cat. No.03CH37439), 2003
ABSTRACT
The 26th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2004
The applicability of OSEM reconstruction algorithms with space dependent resolution recovery to c... more The applicability of OSEM reconstruction algorithms with space dependent resolution recovery to clinical FDG-PET studies is verified. The performance of the 2D algorithm is improved by means of a low resolution initialization and by a infra-iteration Metz filtering. Effects of different rebinning algorithms on 3D data are assessed, concluding that they do not alter the transaxial plane blurring parameters, thus permitting a straightforward application of 2D OSEM reconstruction after rebinning, with the same system matrix. Finally axial degradation was also quantified, finding that FORE is the best rebinning method to be combined with the 2D OSEM reconstruction.
European journal of nuclear medicine, 1998
Functional imaging of the presynaptic dopaminergic activity using single-photon emission tomograp... more Functional imaging of the presynaptic dopaminergic activity using single-photon emission tomography (SPET) and iodine-123 labelled 2-beta-carboxymethoxy-3-beta-(4-iodophenyl)tropane ([123I]beta-CIT) is important for the assessment of disease severity and progression in patients with Parkinson's disease (PD). However, its capability to discriminate between different extrapyramidal disorders has not yet been assessed. The aim of this study was to evaluate the possibility of differentiating patients with PD and with progressive supranuclear palsy (PSP) by means of this method. The distribution of [123I]beta-CIT in the basal ganglia was assessed in six normal subjects, 13 petients with PD and five patients with PSP in whom the disease was mild. SPET images were obtained 24+/-2 h after i.v. injection of the tracer using a brain-dedicated system (CERASPECT). MR and SPET images were co-registered in four normal subjects and used to define a standard set of 16 circular regions of intere...
Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 1994
SPECT studies of regional cerebral perfusion with a high-resolution system were compared to PET s... more SPECT studies of regional cerebral perfusion with a high-resolution system were compared to PET studies of regional cerebral glucose utilization (rCMRglc) in 21 patients with probable Alzheimer's disease (AD). Ten normal subjects were also evaluated with SPECT and 10 with PET. rCMRglc (for PET) and counts (for SPECT) in the associative cortices were normalized to the average rCMRglc, and counts in the calcarine cortex and basal ganglia were considered as a "reference area" to obtain a ratio. The ratio differences between patients and controls were tested with ANOVA performed separately for PET and SPECT. The difference between probable AD patients and controls was significant for both PET (p < 0.00001) and SPECT (p < 0.005); this difference was significant for the frontal, temporal and parietal cortices (p < 0.0001) for PET, and for the temporal (p < 0.005) and parietal (p < 0.001) cortices for SPECT. Temporo-parietal defects were detected in all subject...
Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 1994
One of the limitations of intraoperative tumor detection with radiolabeled monoclonal antibody (M... more One of the limitations of intraoperative tumor detection with radiolabeled monoclonal antibody (Mab), by means of a gamma-detecting probe (GDP), is the long time interval needed between Mab injection and surgery to obtain low blood-pool activity. Such an interval can be shortened considerably, exploiting the high affinity between avidin and biotin. Twenty patients with colorectal cancer were injected with 1 mg of biotinylated 125I monoclonal antibodies followed, 48 hr later, by a chase of cold avidin. During surgery, the GDP was used to detect radioactive emissions from the tumor and normal tissue. Tumor tissue samples were analyzed in vitro by immunohistochemical tests for the presence of tumor antigens and in vivo antibody localization. At the time of surgery (average 7 days postinjection), the mean value of circulating radioactivity was 6% +/- 3% of the injected dose. Of 20 patients studied, tumors were localized in 13 cases (65%). Subclinical tumors were detected in 3 patients (...
Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 1994
Technetium(III)-99m-Q12, trans-(1,2-bis(dihydro-2,2,5,5-tetramethyl- 3(2H)furanone-4-methyleneimi... more Technetium(III)-99m-Q12, trans-(1,2-bis(dihydro-2,2,5,5-tetramethyl- 3(2H)furanone-4-methyleneimino)ethane)bis(tris(3-methoxy-1-propyl) - phosphine)technetium(III)-99m, is a nonreducible complex of Tc(III) which is herein evaluated as a myocardial perfusion imaging agent. The biodistribution and dosimetry of 99mTc-Q12 were assessed in 10 normal volunteers, while its potential clinical use was evaluated in 70 patients. Safety parameters measured up to 24 hr postinjection demonstrate no clinically significant drug-related adverse reactions. Technetium(III)-99m-Q12 exhibits good heart uptake (2.2% injected dose at 1 hr postinjection under resting conditions) and no detectable myocardial washout or redistribution up to 5 hr postinjection. The biodistribution is characterized by very rapid hepatobiliary clearance which allows effective myocardial imaging at times as short as 15 min postinjection. Blood and plasma clearances and myocardial uptake are rapid, while lung uptake is minimal. T...
Journal of Nuclear Medicine, 2003
The aim of this work is the presentation and comparison of state-of-the-art dedicated PET systems... more The aim of this work is the presentation and comparison of state-of-the-art dedicated PET systems actually available on the market, in terms of physical performance and technical features. Particular attention has been given to evaluate the whole-body performance by sensitivity, spatial resolution, dead time, noise equivalent counting rate (NECR), and scatter fraction. PET/CT systems were also included as new proposals to improve diagnostic accuracy of PET, allowing effective anatomic integration to functional data. An overview of actually implemented reconstruction algorithms is also reported to fully understand all of the factors that contribute to image quality.
Radiotherapy and Oncology, 2010
Journal of Nuclear Medicine
Minerva Anestesiologica
A copyedited and fully formatted version will be made available soon. The final version may conta... more A copyedited and fully formatted version will be made available soon. The final version may contain major or minor changes. Subscription: Information about subscribing to Minerva Medica journals is online at: http://www.minervamedica.it/en/how-to-order-journals.php Reprints and permissions: For information about reprints and permissions send an email to:
8.2 Transplantation
A copyedited and fully formatted version will be made available soon. The final version may conta... more A copyedited and fully formatted version will be made available soon. The final version may contain major or minor changes. Subscription: Information about subscribing to Minerva Medica journals is online at: http://www.minervamedica.it/en/how-to-order-journals.php Reprints and permissions: For information about reprints and permissions send an email to:
Medical physics, 2017
Design, realization, scan, and characterization of a phantom for PET Automatic Segmentation (PET-... more Design, realization, scan, and characterization of a phantom for PET Automatic Segmentation (PET-AS) assessment are presented. Radioactive zeolites immersed in a radioactive heterogeneous background simulate realistic wall-less lesions with known irregular shape and known homogeneous or heterogeneous internal activity. Three different zeolite families were evaluated in terms of radioactive uptake homogeneity, necessary to define activity and contour ground truth. Heterogeneous lesions were simulated by the perfect matching of two portions of a broken zeolite, soaked in two different (18) F-FDG radioactive solutions. Heterogeneous backgrounds were obtained with tissue paper balls and sponge pieces immersed into radioactive solutions. Natural clinoptilolite proved to be the most suitable zeolite for the construction of artificial objects mimicking homogeneous and heterogeneous uptakes in (18) F-FDG PET lesions. Heterogeneous backgrounds showed a coefficient of variation equal to 269% ...
Society of Nuclear Medicine Annual Meeting Abstracts, May 1, 2010
Cancer Research, Nov 1, 1991
We describe a method to postlabel, ¡nvivo, biotinylated monoclonal antibodies pretargeted onto t... more We describe a method to postlabel, ¡nvivo, biotinylated monoclonal antibodies pretargeted onto tumor deposits when most of the non-tumorbound antibodies have already been cleared as avidin-bound complexes. The application of this principle to tumor detection by immunoscintigraphy was tested in 20 patients with histológica!!}documented cancer and increased circulating carcinoembryonic antigen levels. One mg of biotinylated anti-carcinoembryonic antigen monoclonal antibody (FO23C5) was administered i.v. (first step). After 3 days, 4-6 mg of cold avidin were injected i.v. (second step), followed 48 h later by 0.2-0.3 mg of a biotin derivative labeled with '"In (2-3 mCi) (third step). No evidence of toxicity was observed. Whole body radioactivity distri bution was measured in five patients at various intervals postinjection by the conjugate counting technique. Tumors and métastases were detected in 18 of 19 patients (the remaining patient was a true negative) within 3 h after administration of '"In-biotin by planar or single photon emission tomography imaging. At the time of imaging, tumor/blood pool ratio was 5.5 ±3.2, and tumor/liver ratio was 6.7 ±3.9. Blood clearance of '"Inbiotin was multiexponential, with the fast component having a i. of 5 ± 3 min. Urinary excretion of radioactivity over 3 h was 63.5 ±4.9% of the injected dose. Radioactivity at 3 h was 6.5 ±1.8% in blood, 1.6 ± 0.3% in the kidney, and 2.4 ±0.6% in the liver. This approach represents an improvement in immunoscintigraphic techniques for tumor localization. The potential use for radioimmunotherapy is discussed.
Medical Physics, 2016
Quantitative (18)F-fluorodeoxyglucose positron emission tomography is limited by the uncertainty ... more Quantitative (18)F-fluorodeoxyglucose positron emission tomography is limited by the uncertainty in lesion delineation due to poor SNR, low resolution, and partial volume effects, subsequently impacting oncological assessment, treatment planning, and follow-up. The present work develops and validates a segmentation algorithm based on statistical clustering. The introduction of constraints based on background features and contiguity priors is expected to improve robustness vs clinical image characteristics such as lesion dimension, noise, and contrast level. An eight-class Gaussian mixture model (GMM) clustering algorithm was modified by constraining the mean and variance parameters of four background classes according to the previous analysis of a lesion-free background volume of interest (background modeling). Hence, expectation maximization operated only on the four classes dedicated to lesion detection. To favor the segmentation of connected objects, a further variant was introduced by inserting priors relevant to the classification of neighbors. The algorithm was applied to simulated datasets and acquired phantom data. Feasibility and robustness toward initialization were assessed on a clinical dataset manually contoured by two expert clinicians. Comparisons were performed with respect to a standard eight-class GMM algorithm and to four different state-of-the-art methods in terms of volume error (VE), Dice index, classification error (CE), and Hausdorff distance (HD). The proposed GMM segmentation with background modeling outperformed standard GMM and all the other tested methods. Medians of accuracy indexes were VE &amp;amp;amp;lt;3%, Dice &amp;amp;amp;gt;0.88, CE &amp;amp;amp;lt;0.25, and HD &amp;amp;amp;lt;1.2 in simulations; VE &amp;amp;amp;lt;23%, Dice &amp;amp;amp;gt;0.74, CE &amp;amp;amp;lt;0.43, and HD &amp;amp;amp;lt;1.77 in phantom data. Robustness toward image statistic changes (±15%) was shown by the low index changes: &amp;amp;amp;lt;26% for VE, &amp;amp;amp;lt;17% for Dice, and &amp;amp;amp;lt;15% for CE. Finally, robustness toward the user-dependent volume initialization was demonstrated. The inclusion of the spatial prior improved segmentation accuracy only for lesions surrounded by heterogeneous background: in the relevant simulation subset, the median VE significantly decreased from 13% to 7%. Results on clinical data were found in accordance with simulations, with absolute VE &amp;amp;amp;lt;7%, Dice &amp;amp;amp;gt;0.85, CE &amp;amp;amp;lt;0.30, and HD &amp;amp;amp;lt;0.81. The sole introduction of constraints based on background modeling outperformed standard GMM and the other tested algorithms. Insertion of a spatial prior improved the accuracy for realistic cases of objects in heterogeneous backgrounds. Moreover, robustness against initialization supports the applicability in a clinical setting. In conclusion, application-driven constraints can generally improve the capabilities of GMM and statistical clustering algorithms.
Society of Nuclear Medicine Annual Meeting Abstracts, May 1, 2009
Society of Nuclear Medicine Annual Meeting Abstracts, May 1, 2010
European Journal of Nuclear Medicine and Molecular Imaging, Apr 30, 1994
The physical performances of two current state-of-the-art scanners dedicated to functional imagin... more The physical performances of two current state-of-the-art scanners dedicated to functional imaging of the brain, one a single-photon emission tomography (SPET) scanner and the other a positron emission tomography (PET) scanner, have been compared under identical conditions. The aim of the study was to compare the capabilities of the devices under conditions resembling the routine clinical environment, as well as to consider other issues such as radiation burden for some common investigations. Both systems have slightly less than 11-cm axial fields of view. The PET system can be operated in a septa-less (3D) mode as well as conventionally with septa (2D). The spatial resolution of both devices was less than 8 mm in all dimensions in scattering media. On average, the PET scanner's resolution was approximately 10%-15% better than the SPET system. Energy resolution on the SPET system was superior due the scintillator used [NaI(T1)]. Sensitivity in air with a line source on the PET system was found to be-150 times greater in 3D and-25 times greater in 2D than with the SPET system. A normal subject was studied on each system in an attempt to obtain the highest quality data possible for a subjective comparison. It is clear that, while PET retains the advantages of more desirable radiopharmaceuticals and higher sensitivity, the quality obtainable from SPET devices has improved markedly. SPET may prove as useful for many clinical investigations.
Nuclear Instruments and Methods in Physics Research Section a Accelerators Spectrometers Detectors and Associated Equipment, Feb 1, 2007
The effect of malfunctioning detector blocks on accuracy of PET reconstructed images was evaluate... more The effect of malfunctioning detector blocks on accuracy of PET reconstructed images was evaluated qualitatively and quantitatively, by using the ECAT EXACT HR+ scanner. A procedure to simulate defective block was carried out after analyzing and comparing blank scans obtained with ...
European Respiratory Journal, 2015
The aim of the study was to determine the size and location of homogeneous inflamed/noninflamed a... more The aim of the study was to determine the size and location of homogeneous inflamed/noninflamed and inhomogeneous inflamed/noninflamed lung compartments and their association with acute respiratory distress syndrome (ARDS) severity.In total, 20 ARDS patients underwent 5 and 45 cmH2O computed tomography (CT) scans to measure lung recruitability. [18F]2-fluoro-2-deoxy-d-glucose ([18F]FDG) uptake and lung inhomogeneities were quantified with a positron emission tomography-CT scan at 10 cmH2O. We defined four compartments with normal/abnormal [18F]FDG uptake and lung homogeneity.The homogeneous compartment with normal [18F]FDG uptake was primarily composed of well-inflated tissue (80±16%), double-sized in nondependent lung (32±27% versus 16±17%, p<0.0001) and decreased in size from mild, moderate to severe ARDS (33±14%, 26±20% and 5±9% of the total lung volume, respectively, p=0.05). The homogeneous compartment with high [18F]FDG uptake was similarly distributed between the dependent...
Proceedings of the 25th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (IEEE Cat. No.03CH37439), 2003
ABSTRACT
The 26th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2004
The applicability of OSEM reconstruction algorithms with space dependent resolution recovery to c... more The applicability of OSEM reconstruction algorithms with space dependent resolution recovery to clinical FDG-PET studies is verified. The performance of the 2D algorithm is improved by means of a low resolution initialization and by a infra-iteration Metz filtering. Effects of different rebinning algorithms on 3D data are assessed, concluding that they do not alter the transaxial plane blurring parameters, thus permitting a straightforward application of 2D OSEM reconstruction after rebinning, with the same system matrix. Finally axial degradation was also quantified, finding that FORE is the best rebinning method to be combined with the 2D OSEM reconstruction.
European journal of nuclear medicine, 1998
Functional imaging of the presynaptic dopaminergic activity using single-photon emission tomograp... more Functional imaging of the presynaptic dopaminergic activity using single-photon emission tomography (SPET) and iodine-123 labelled 2-beta-carboxymethoxy-3-beta-(4-iodophenyl)tropane ([123I]beta-CIT) is important for the assessment of disease severity and progression in patients with Parkinson's disease (PD). However, its capability to discriminate between different extrapyramidal disorders has not yet been assessed. The aim of this study was to evaluate the possibility of differentiating patients with PD and with progressive supranuclear palsy (PSP) by means of this method. The distribution of [123I]beta-CIT in the basal ganglia was assessed in six normal subjects, 13 petients with PD and five patients with PSP in whom the disease was mild. SPET images were obtained 24+/-2 h after i.v. injection of the tracer using a brain-dedicated system (CERASPECT). MR and SPET images were co-registered in four normal subjects and used to define a standard set of 16 circular regions of intere...
Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 1994
SPECT studies of regional cerebral perfusion with a high-resolution system were compared to PET s... more SPECT studies of regional cerebral perfusion with a high-resolution system were compared to PET studies of regional cerebral glucose utilization (rCMRglc) in 21 patients with probable Alzheimer's disease (AD). Ten normal subjects were also evaluated with SPECT and 10 with PET. rCMRglc (for PET) and counts (for SPECT) in the associative cortices were normalized to the average rCMRglc, and counts in the calcarine cortex and basal ganglia were considered as a "reference area" to obtain a ratio. The ratio differences between patients and controls were tested with ANOVA performed separately for PET and SPECT. The difference between probable AD patients and controls was significant for both PET (p < 0.00001) and SPECT (p < 0.005); this difference was significant for the frontal, temporal and parietal cortices (p < 0.0001) for PET, and for the temporal (p < 0.005) and parietal (p < 0.001) cortices for SPECT. Temporo-parietal defects were detected in all subject...
Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 1994
One of the limitations of intraoperative tumor detection with radiolabeled monoclonal antibody (M... more One of the limitations of intraoperative tumor detection with radiolabeled monoclonal antibody (Mab), by means of a gamma-detecting probe (GDP), is the long time interval needed between Mab injection and surgery to obtain low blood-pool activity. Such an interval can be shortened considerably, exploiting the high affinity between avidin and biotin. Twenty patients with colorectal cancer were injected with 1 mg of biotinylated 125I monoclonal antibodies followed, 48 hr later, by a chase of cold avidin. During surgery, the GDP was used to detect radioactive emissions from the tumor and normal tissue. Tumor tissue samples were analyzed in vitro by immunohistochemical tests for the presence of tumor antigens and in vivo antibody localization. At the time of surgery (average 7 days postinjection), the mean value of circulating radioactivity was 6% +/- 3% of the injected dose. Of 20 patients studied, tumors were localized in 13 cases (65%). Subclinical tumors were detected in 3 patients (...
Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 1994
Technetium(III)-99m-Q12, trans-(1,2-bis(dihydro-2,2,5,5-tetramethyl- 3(2H)furanone-4-methyleneimi... more Technetium(III)-99m-Q12, trans-(1,2-bis(dihydro-2,2,5,5-tetramethyl- 3(2H)furanone-4-methyleneimino)ethane)bis(tris(3-methoxy-1-propyl) - phosphine)technetium(III)-99m, is a nonreducible complex of Tc(III) which is herein evaluated as a myocardial perfusion imaging agent. The biodistribution and dosimetry of 99mTc-Q12 were assessed in 10 normal volunteers, while its potential clinical use was evaluated in 70 patients. Safety parameters measured up to 24 hr postinjection demonstrate no clinically significant drug-related adverse reactions. Technetium(III)-99m-Q12 exhibits good heart uptake (2.2% injected dose at 1 hr postinjection under resting conditions) and no detectable myocardial washout or redistribution up to 5 hr postinjection. The biodistribution is characterized by very rapid hepatobiliary clearance which allows effective myocardial imaging at times as short as 15 min postinjection. Blood and plasma clearances and myocardial uptake are rapid, while lung uptake is minimal. T...