Nuclear Medicine and PET-CT

Cyclotron produced radionuclides played an important role to shape the nuclear medicine practice to the current level. Low energy (9-18 MeV) cyclotrons are used for the preparation of radionuclides and radiopharmaceuticals for  PET-CT imaging.  While [18F]fluorodeoxyglucose (FDG) is the most common radiopharmaceutical prepared using the above machines; a number of other tracers useful in oncology and neurology can also be prepared with 18F.
Cyclotrons having proton energy upto 30 MeV have been in use for the preparation of radionuclides such as 201Tl, 123I, 111In and 67Ga for single photon emission computed tomography (SPECT) imaging.  The radiopharmaceuticals sciences and nuclear medicine have been evolving and many of the highly desired radionuclides in the past are finding lesser demand as replacement radiopharmaceuticals with 99mTc or PET radionuclides have been developed.
A major advance in the last decade is the emergence of the PET radionuclide, 68Ga which is the daughter of the long lived 68Ge (T1/2 271 days). Similar to 99mTc, 68Ga offers the versatility for the preparation of tracers for varied applications. Gallium-68 will be a major driver of nuclear medicine in the coming years. A 30 MeV cyclotron offers the possibility to make significant amounts of 68Ge which can be used for the preparation of 68Ge/68Ga generator.  68Ga-DOTATATE and 68Ga-PSMA are now used for the detection, staging, therapy monitoring and recurrence evaluation of neuroendocrine tumors (NETs) and prostate cancer, respectively.  More such products are expected to be developed in future making 68Ge/68Ga generator an indispensable radionuclide source in a nuclear medicine department.

a For β − particles the maximum β − energy is mentioned. Auger electron energy is the average kinetic energy of Auger and Coster− Kronig electrons emitted per decay. Figure 11. Calculated 177m Lu/ 177 Lu ratios as a function of the irradiation period and thermal neutron flux. Reprinted with permission from ref 85. a MTC = medullary thyroid carcinoma, SCLC = small cell lung cancer, α-MSH = alpha melanocyte stimulating hormone, BB = bombesin, NK = neurokinin, NT = neurotensin, ET = endothelin, ANP = atrial natriuretic peptide, LNRH = luteinizing hormone-releasing hormone, NPY = neuropeptide Y, GLP = gastrin-releasing peptide.

Peptide receptor radionuclide therapy (PRRT) is a site-directed targeted therapeutic strategy that specifically
uses radiolabeled peptides as biological targeting vectors designed to deliver cytotoxic levels of radiation dose
to cancer cells, which overexpress specific receptors. Interest in PRRT has steadily grown because of the
advantages of targeting cellular receptors in vivo with high sensitivity as well as specificity and treatment at the
molecular level. Recent advances in molecular biology have not only stimulated advances in PRRT in a
sustainable manner but have also pushed the field significantly forward to several unexplored possibilities.
Recent decades have witnessed unprecedented endeavors for developing radiolabeled receptor-binding somatostatin
analogs for the treatment of neuroendocrine tumors, which have played an important role in the
evolution of PRRT and paved the way for the development of other receptor-targeting peptides. Several
peptides targeting a variety of receptors have been identified, demonstrating their potential to catalyze
breakthroughs in PRRT. In this review, the authors discuss several of these peptides and their analogs with
regard to their applications and potential in radionuclide therapy. The advancement in the availability of
combinatorial peptide libraries for peptide designing and screening provides the capability of regulating immunogenicity
and chemical manipulability. Moreover, the availability of a wide range of bifunctional chelating
agents opens up the scope of convenient radiolabeling. For these reasons, it would be possible to envision a
future where the scope of PRRT can be tailored for patient-specific application. While PRRT lies at the
interface between many disciplines, this technology is inextricably linked to the availability of the therapeutic
radionuclides of required quality and activity levels and hence their production is also reviewed.

The medical field especially oncology has significantly benefitted from a machine called cyclotron which was originally developed for nuclear physics experiments. Cyclotrons are used for the preparation of radiopharmaceuticals for positron emission tomography (PET) imaging which is an essential need for cancer diagnosis and management. Cyclotrons are also used for the preparation of radioisotopes for targeted alpha therapy. This article reviews the growth of this field and the current status in India.

Aim: Integrinαvβ3plays a significant role in angiogenesis during tumor growth and metastasis, and is a receptor for
the extracellular matrix proteins with the exposed arginine(R)-glycine(G)-aspartic acid(D) tripeptide sequence.
The over-expression of integrin αvβ3 during tumor growth and metastasis presents an interesting molecular target
for both early detection and treatment of rapidly growing solid tumors. Considering the advantages of 177Lu for
targeted radiotherapy and enhanced tumor targeting capability of cyclic RGD peptide dimer, an attempt has been
made to optimize the protocol for the preparation of clinical dose of 177Lu labeled DOTA-E[c(RGDfK)]2 (E =
Glutamic acid, f = phenyl alanine, K = lysine) as a potential agent for targeted tumor therapy.
Methods: 177Lu was produced by thermal neutron bombardment on enriched Lu2O3 (82% in 176Lu) target at a flux
of 1 × 1014 n/cm2
.s for 21 d. Therapeutic dose of 177Lu-DOTA-E[c(RGDfK)]2 (7.4 GBq) was prepared by adding the
aqueous solution of the ligand and 177LuCl3 to 0.1 M NH4OAC buffer containing gentisic acid and incubating the
reaction mixture at 90 °C for 30 min. The yield and radiochemical purity of the complex was determined by HPLC
technique. Parameters, such as, ligand-to-metal ratio, pH of the reaction mixture, incubation time and
temperature were varied using tracer quantity of 177Lu (37 MBq) in order to arrive at the optimized protocol
for the preparation of clinical dose. Biological behavior of the radiotracer prepared was studied in C57/BL6 mice
bearing melanoma tumors.
Results: 177Lu was produced with a specific activity of 950 ± 50 GBq/mg (25.7 ± 1.4 Ci/mg) and radionuclidic
purity of 99.98%. A careful optimization of several parameters showed that 177Lu-DOTA-E[c(RGDfK)]2 could be
prepared with adequately high radiochemical purity using a ligand-to-metal ratio ~2. Based on these studies
therapeutic dose of the agent with 7.4 GBq of 177Lu was formulated in ~63 GBq/μM specific activity with high
yield (98.2 ± 0.7%), radiochemical purity and in vitro stability. Biodistribution studies carried out in C57/BL6 mice
bearing melanoma tumors revealed specific accumulation of the radiolabeled conjugate in tumor (3.80 ± 0.55%
ID/g at 30 min p.i.) with high tumor to blood and tumor to muscle ratios. However, the uptake of the radiotracer in
the tumor was found to be reduced to 1.51 ± 0.32 %ID/g at 72 h p.i.
Conclusions: The present work successfully demonstrates the formulation of an optimized protocol for the
preparation of 177Lu labeled DOTA-E[c(RGDfK)]2 for PRRT applications using 177Lu produced by direct neutron
activation in a medium flux research reactor.

Understanding the hallmarks of cancer is valuable in advancing drug development to fight the disease. With the advent of molecular imaging, non-invasive in vivo visualization of physiology and functional pathways allow for multiple levels of disease and therapy assessment beyond tumor size measurements offered by conventional anatomic scans. Radiolabeling targeted molecules can provide insight into tumor interactions within the body and may help guide therapeutic constructs. Traditionally, radiolabeled probes have been useful for staging and diagnosis but they can also be created to monitor and identify drug targets and pharmaceutical biodistribution among other novel approaches. Radiotracers can be imaged either through single photon emission computed tomography (SPECT) or positron emission tomography (PET), with advantages and limitations to both. Adding CT to either modality is an added benefit for anatomic localization and attenuation correction.  In this review, we will briefly discuss several molecular imaging agents, which target metabolism (18F-FDG, 18F-FACBC, 11C acetate), proliferation (18F-FLT, 18F-5FU, 18F-FdCyd), and cancer specific drug receptors (111In-morab009, 111In-trastuzumab, 89Zr-panutumumab).  Molecular imaging is a powerful tool that one day, may be employed to personalize treatment and dosing strategies and predict anticancer therapy outcomes.

ABSTRACT

Introduction

It is reported that the healthcare workforce in Zambia is inadequate for the healthcare needs of the country. This stems from healthcare professionals, particularly radiographers, exiting the public health sector for non-governmental organizations or other countries with attractive conditions of service. It has been argued that employees are more likely to be satisfied with their job and retained when their expectations are met. Workplace experiences can influence employee satisfaction and retention, negatively or positively. The aim of the study was to explore and describe the workplace experiences of radiographers in the public health sector in the province of Lusaka in Zambia and to examine how these experiences influence job satisfaction and staff retention.

Methodology

This research was a qualitative, explorative, descriptive study which adopted a constructivist paradigm, using a case study approach. Radiographers working in four public hospitals in Lusaka were included in the study. Using purposive sampling, thirty-nine (39) radiographers who met the inclusion criteria participated in the study. Data was collected using a semi-structured interview schedule. An audio recorder was used to capture the interviews, which were transcribed verbatim. The data was analyzed using a thematic approach and the themes were derived and interpreted in relation to the main concepts in Herzberg’s Two-Factor Theory (Herzberg’s TFT).

Results

Five main themes were identified from the data, namely: physical work environment, staff workloads, remuneration and incentives, leadership style, and professional development. With regard to the physical work environment, radiographers reported inadequate ventilation, particularly in the imaging rooms, insufficient imaging equipment, accessories and consumables, outmoded and faulty equipment, inadequate patient spaces, inadequate working and resting spaces for staff. Regarding remuneration and incentives, the participants highlighted inadequate salaries and non-availability of incentives and rewards. Participants reported inflexible work allocation, inadequate staffing, and excessive workloads as challenges related to staff workloads. Challenges regarding the theme of the style of leadership and supervision included lack of the following: openness to modern management approaches, emotional intelligence on the part of leadership, autonomy in the workplace, and motivation and appreciation of staff. With respect to professional development, the participants expressed an appreciation for continuing professional development (CPD) opportunities and workshops including the opportunities for new learning experiences. The lack of advocacy by the relevant radiography professional bodies and/or societies was also highlighted. The findings show that the challenges experienced by the radiographers, within the workplace, negatively influence job satisfaction and staff retention, which in turn impacts negatively on imaging service delivery.

Discussion

Herzberg’s (TFT) was selected to provide a meaningful interpretation of the findings, as it highlights the hygiene and motivator factors that affect job satisfaction. The hygiene factors refer to the physical work environment, working conditions, remuneration and rewards, leadership and management. A safe and conducive work environment is essential for radiographers to undertake their daily tasks effectively. They have a right to work in a physical work environment that has adequate spaces, sufficient ventilation and uninterrupted water supply to ensure proper infection control measures as well as to minimize occupational health risks. They also require updated and properly maintained imaging equipment and related ancillaries to provide optimal imaging service delivery. They also experience a higher level of satisfaction when they have a suitable place to rest. Radiographers’ job dissatisfaction is greater when they receive inadequate salaries and there is lack of other rewards and incentives such as radiation risk and overtime allowances. Radiographers experience job satisfaction when they have manageable workloads and there is an adequate staff patient ratio. Staffing shortages lead to increased workloads, which in turn contribute to increasing work-related stressors. Radiographers experience higher levels of job satisfaction and are likely to remain in their positions when their efforts are recognised and rewarded by their respective managers and/or leaders. In addition, radiographers thrive in a work environment that fosters autonomy.
The motivator factor in Herzberg’s (TFT) refers to professional development and employee recognition. Radiographers recognize that CPD is essential to maintain professional aptitude and they also recognize the significance of the professional body in the development of the profession as well as the role that public hospitals play in providing opportunities for continuing learning. Therefore, it is imperative the radiographers are provided with adequate opportunities for professional development and lifelong learning, especially in the ‘era of uncertainty’.

Conclusion

Radiographers, working in the selected public hospitals in the province of Lusaka, experience many challenges in their workplaces. The challenges are related to the physical work environment, remunerations and rewards, staff workloads, leadership style, and CPD which negatively affect job satisfaction and staff retention among public service radiographers. Failure by the employers to address these challenges results in employee job dissatisfaction and negatively affects staff retention. To enhance job satisfaction among public service radiographers, the employers need to support professional development, and recognize and reward performance. This study could contribute positively to enhancing the radiographers’ work environment, which could enhance job satisfaction and staff retention among public service radiographers.

Data on the distribution of nuclear medicine centers in the country serves as a reference and an archive of the status of nuclear medicine in the country.
An analysis for the state wise distribution of nuclear medicine centers ,therapy centers, cyclotrons and diagnostic centers state wise is presented. This analysis indicates which states  have  few such facilities and where the discipline needs to work hard to initiate and establish centers for the benefit of the population.
Veterinary nuclear medicine a fairly new concept has a vast potential for diagnostic and therapeutic applications which need to be exploited as early as possible.

Aim
Q. Freeze Software for Respiratory Motion Correction in PET/CT: A Preliminary Investigation with a Respiratory Motion Phantom
G. Havariyoun, D. Ruiz, E. Kalogianni, B. Corcoran, N. Mulholland, G. Vivian
PET/CT imaging of the lung and abdominal region can often lead to apparent increase in tumour volume, underestimation of measured standardized uptake value (SUV), and mismatched PET and CT images due to respiratory motion. GE Healthcare Q.Freeze software uses 100% of the detected events and can perform respiratory phase matching of gated PET and low-dose 4D-CT data to minimize respiratory motion artefacts.
This investigation aimed to assess the effectiveness of the Q.Freeze software.
Material and methods
The GE Discovery 710 PET/CT scanner was used to scan the Quasar® Respiratory Motion Phantom (QRMP) with two in-house constructed inserts. The QRMP inserts consisted of 4ml and 1ml 18F-FDG filled spheres in air and water to model spherical lesions in lung and liver respectively. Scans were performed with a sinusoidal respiratory waveform of 20 breaths per minute (bpm) with 20mm amplitude and a single patient specific respiratory cycle pattern. Varian’s Real-Time Position Management System was used to monitor the phantom’s motion. Images acquired when the QRMP was motionless were used as benchmark. For each motion experiment three sets of images were reconstructed; ungated PET (UG-PET), Q.Freeze PET only gated (4D-PET) and finally Q.Freeze PET with cine CT (4D-PET/CT). Images obtained were quantitatively assessed for background variability (BV), sphere volume and SUVs. All analysis was performed on a Hermes® nuclear medicine workstation.
Results
UG-PET images had the largest increase in volume and reduction in SUV when compared to benchmark in all images.
BV was largest for the 4D-PET/CT in all acquired images.
4D-PET and 4D-PET/CT improved accuracy by increasing SUVmax by a mean of 33% and 31% (compared to UG-PET) and decreasing volume by a mean of 216% and 211% (compared to UG-PET) respectively.
The improvement was greater in all cases for 4D-PET compared to 4D-PET/CT, apart from in air where 4D-PET/CT showed marginal enhancement by increasing SUVmax by 5% (compared to 4D-PET) and decreasing volume by 14%.
Conclusion
Preliminary results clearly indicate that Q.Freeze largely improves SUV and volume figures when compared to UG-PET images. These results do not justify the extra radiation exposure to patients if 4D PET/CT was performed. The next step of this study will involve the construction of an insert that will replicate lesions on the liver-lung boundary.

Owing to its favourable decay characteristics 175Yb (T1=2 ¼ 4:2d, EbðmaxÞ ¼ 480 keV) can be regarded as a potential
radionuclide for therapeutic applications. Production of 175Yb using (174Yb(n; g)175Yb) reaction by thermal neutron
bombardment on natural ytterbium target is described. The activity of 175Yb produced as well as its radionuclidic purity
under different irradiation conditions were determined by g-ray spectrometry using an HPGe 4K MCA system and
compared with theoretically calculated values. The radiochemical purity after chemical processing was determined by
paper chromatography as well as paper electrophoresis techniques. It is found that 31 Ci/g (1145 GBq/g) of 175Yb can
be produced with >95% radionuclidic purity (with B3% of 169Yb and B2% of 177Lu) by irradiating natural Yb2O3
target at a thermal neutron flux of 31013 n/cm2/s for a period of 5 d. r 2002 Elsevier Science Ltd. All rights reserved.
Keywords: Therapeutic radionuclide; 175Yb; 169Yb; Radionuclidic purity; Radiochemical purity; Specific activity

Ketone bodies – 3-hydroxybutyrate and acetoacetate – are important fuel substrates, which can be oxidized by most tissues in the body. They are synthesized in the liver and are derived from fatty acids released from adipose tissue. Intriguingly, under conditions of stress such as fasting, arterio-venous catheterization studies have shown that the brain switches from the use of almost 100% glucose to the use of > 50–60% ketone bodies. A similar adaptive mechanism is observed in the heart, where fasting induces a shift toward ketone body uptake that provides the myocardium with an alternate fuel source and also favorably affects myocardial contractility. Within the past years there has been a renewed interest in ketone bodies and the possible beneficial effects of fasting/semi-fasting/exercising and other " ketogenic " regimens have received much attention. In this perspective, it is promising that positron emission tomography (PET) techniques with isotopically labeled ketone bodies, fatty acids and glucose offer an opportunity to study interactions between ketone body, fatty acid and glucose metabolism in tissues such as the brain and heart. PET scans are non-invasive and thus eliminates the need to place catheters in vascular territories not easily accessible. The short half-life of e.g. 11C-labeled PET tracers even allows multiple scans on the same study day and reduces the total radiation burden associated with the procedure. This short review aims to give an overview of current knowledge on ketone body metabolism obtained by PET studies and discusses the methodological challenges and perspectives involved in PET ketone body research.

The present handbook is a concise and comprehensive compendium for students illustrating synthetically the principals of Nuclear Medicine discipline. It provides the reader with a balanced overview of the technical aspects and main indications of Nuclear Medicine procedures in clinical practice. The text is addressed primarily to the degree courses for technologists, but can be a useful tool for medical students and a practical guide for other professionals and training courses.

Positron emission computed tomography (PET), a complex nuclear medicine imaging modality, is rapidly gaining in use for clinical applications. Unfortunately, greater complexity and probability of equipment failures are expected with PET compared to traditional nuclear medicine instruments. It is anticipated that as PET technology becomes more widespread and shortages of PET physicists occur, the nuclear medicine technologist will have more responsibility in the areas of instrument diagnostics, quality assurance (QA), and trouble shooting. In addition, PET instruments in the clinical envi ronment must be operated under the added pressure of having to withstand high patient throughput while maintaining quan titative accuracy.

This study was performed Nuclear Medicine Department of Fadil Specialist Center and Elnileen Medical Center in Khartoum for 25 Ischemic heart disease patients associated with CAO. This paper presented an appropriate approach for the robust estimation of noise statistic in nuclear cardiology images. The main objective of this study was to Improve of
Nuclear Cardiology Images for Ischemic Patients using Image Processing Techniques. For the Single Photon Emission Computed Tomography machine (SPECT) each imaged had
been taken for each single case with guidance of ECG trigger by injected patients with (20mci) of Tc99m-MIBI, then patient wait for 45 min to 1 hour. The scanned image saved as TIFF format images in computer for reservation of image quality. The data analyzed using MatLab program to enhance the cardiac images and adenosine them. To achieve maximum
image quality after denoising, a new, low order, local adaptive Gaussian Scale Mixture model is presented, which accomplishes nonlinearities from scattering. State of art methods use multi scale filtering of images to reduce the irrelevant part of information, based on generic estimation of noise. In this, paper, prominent constraints are firstly preservation of image's overall look; secondly, preservation of the diagnostic content in the image and thirdly detection of small low contrast details in diagnostic content of the image.

Deep learning (DL) has seen an exponential development in recent years, with major impact in many medical fields, especially in the field of medical image. The purpose of the work converges in determining the importance of each component, describing the specificity and correlations of these elements involved in achieving the precision of interpretation of medical images using DL. The major contribution of this work is primarily to the updated characterisation of the characteristics of the constituent elements of the deep learning process, scientific data, methods of knowledge incorporation, DL models according to the objectives for which they were designed and the presentation of medical applications in accordance with these tasks. Secondly, it describes the specific correlations between the quality, type and volume of data, the deep learning patterns used in the interpretation of diagnostic medical images and their applications in medicine. Finally presents problems and directions of future research. Data quality and volume, annotations and labels, identification and automatic extraction of specific medical terms can help deep learning models perform image analysis tasks. Moreover, the development of models capable of extracting unattended features and easily incorporated into the architecture of DL networks and the development of techniques to search for a certain network architecture according to the objectives set lead to performance in the interpretation of medical images.

Content-Based Image Retrieval (CBIR) locates, retrieves and displays images alike to one given as a query, using a set of features. It demands accessible data in medical archives and from medical equipment, to infer meaning after some processing. A problem similar in some sense to the target image can aid clinicians. CBIR complements text-based retrieval and improves evidence-based diagnosis, administration, teaching, and research in healthcare. It facilitates visual/automatic diagnosis and decision-making in real-time remote consultation/screening, store-and-forward tests, home care assistance and overall patient surveillance. Metrics help comparing visual data and improve diagnostic. Specially designed architectures can benefit from the application scenario. CBIR use calls for file storage standardization, querying procedures, efficient image transmission, realistic databases, global availability, access simplicity, and Internet-based structures. This chapter recommends important and complex aspects required to handle visual content in healthcare.

Positron emission tomography (PET) is a new imaging modality offering anatomic and metabolic information and it is being used to differentiate benign from malignant lesions. The aim of this study is to evaluate the result of the PET analysis in the patients who were performed surgery after PET examination.

Descripción detallada de los equipos y métodos empleados para obtener los distintos tipos de estudios de Medicina Nuclear y  de los métodos de reconstrucción tomográfica FBP y MLEM-OSEM.
Se parte de la radiactividad y su detección  para progresivamente exponer como se forman las imágenes y como se agrupan para formar  los estudios estándar de Medicina nuclear incluyendo SPECT y PET.
Puede ser de interés para profesionales de Medicina Nuclear tanto físicos como médicos y técnicos que se inicien en este campo o que deseen profundizar sus conocimientos de los equipos que usan rutinariamente. Es un texto eminentemente descriptivo escrito con rigor y sin tecnicismos innecesarios. en el que se ha empleado un mínimo de expresiones matemáticas que se explican en el texto.

The thyroid gland is an important endocrine gland in the body. It produces the hormones T3, T4 and calcitonin. Thyroid cancer is one of the common cancers and women have three times higher incidence than men. There are four different subtypes of thyroid cancers and the prognosis depends on these subtypes. Thyroid cancers are managed by surgery, radiation therapy, chemotherapy and targeted radionuclide therapy. Abbreviations Thyroid cancer is one of the common cancers and accounts for about 3-4% of all the cancers reported. Women are three times more prone to thyroid cancer than men. It is the sixth most common cancer in women [1]. The disease starts in the thyroid gland and unless treated can spread to any part of the body. Five year survival rate for thyroid cancer is 98%. The survival is based on many factors including the sub type of cancer and the clinical stage of the disease at the time of diagnosis.

Four cases of brain abscess in neonates are described, diagnosed by ultrasonography and CT. All abscesses were confirmed surgically. One patient was operated on 5 weeks after diagnosis because of initial parental refusal. The etiology in all cases was meningitis superimposed on an hypoxic-ischemic insult. Two cases had a single abscess while the Other two had multiple lesions. All cases were operated on with intraoperative ultrasound examination through the fontanelle. The case with delayed aspiration showed complete evolution from localized cerebritis to complete capsule formation with mass effect. One abscess was sterile, and in the others grew Klebsiella pneurnoniae and Enterobacter aerogenes. The microorganism initially isolated from the lumbar CSF was also found in the abscess. Even after sterilization of the lumbar CSF, all abscesses were still present. Ultrasound examination and CT are compared.

Tesi volta a esporre come l'utilizzo della PET-TC sia fondamentale nel campo dell'oncologia anche pediatrica, tramite determinati accorgimenti che hanno lo scopo di ridurre la dose di radiazioni ionizzanti al valore minimo indicato dalle linee guida internazionali di radioprotezione in medicina nucleare. La tesi andrà a spiegare come il Tecnico Radiologo di medicina nucleare  andrà ad effettuare questa tipologia di esame diagnostico su di un paziente pediatrico.

The positron range, that is, the distance from the positron emission point to the annihilation one in β + decay, limits the spatial resolution of PET images. Thus, any realistic simulation of PET acquisitions must include this effect as accurately as possible. Positron range distributions have been computed and compared in the literature. Not all authors present it in the same way. For instance, accumulated range distributions, 1D projection of the positrons annihilation coordinates, or angular integrated 3D radial distributions, have been used. Any of these presentations may emphasize a different physical property. Thus it is difficult to perform a meaningful comparison of the results obtained by different authors. The aim of this work is to present a general framework to compare positron range distributions. We use a genetic algorithm to fit the radial, angle integrated, g 3D (r) distribution of the annihilation points to any positron annihilation distribution chosen as reference. Therefore, given a positron range distribution presented in a certain way, we can obtain the distributions, first fitting g 3D and then using the relations between distributions. Using this procedure, positron range distributions available in the literature are compared with the ones computed with the simulation package PeneloPET

A new phantom design to determine spatial resolution in Single Photon Emission Computed Tomography (SPECT) imaging systems is described. Specifically, spatial resolution in terms offull width at halfmaximum (FWHM) values can be determined simultaneously at multiple areas within the volumetric field of view. These values can then be assigned to their respective position or "mapped" within the field of view to demonstrate variations in spatial resolution.

669 e report the case of a patient with bronchioloalveolar carcinoma with focal nodular hyperplasia of the hematopoietic marrow in dorsal vertebral bodies revealed on FDG positron emission tomography (PET) and MR imaging. Differentiation with metastatic disease is discussed.

The infection of a vascular prosthesis (VGI) is the most serious complication in prosthetic vascular reconstructive surgery, burdened by a high rate of mortality and morbidity. The treatment of a VGI, in most cases, consists of its surgical removal, and therefore an accurate diagnosis of the infection, is of paramount importance in clinical practice since false-positive results may lead to unnecessary major surgery whereas false-negative results are related with high-risk morbidity. Furthermore, early diagnosis of infection permits a wider range of therapeutic options and a less aggressive surgical approach. On the basis of the documents and abstracts published in the last 25 years, the authors analyze and discuss the contribution of nuclear medicine in the management of these infections, evaluating the reliability of scintigraphy with labeled leukocytes, other gamma-emitting radiopharmaceuticals, PET and PET / CT with 18F-Fluorodeoxiglucose.