Small animal PET scanner based on monolithic LYSO crystals: performance evaluation.

PURPOSE: The authors have developed a small animal Positron emission tomography (PET) scanner based on monolithic LYSO crystals coupled to multi-anode photomultiplier tubes (MA-PMTs). In this study, the authors report on the design, calibration procedure, and performance evaluation of a PET system that the authors have developed using this innovative nonpixelated detector design. METHODS: The scanner is made up of eight compact modules forming an octagon with an axial field of view (FOV) of 40 mm and a transaxial FOV of 80 mm diameter. In order to fully determine its performance, a recently issued National Electrical Manufacturers Association (NEMA) NU-4 protocol, specifically developed for small animal PET scanners, has been followed. By measuring the width of light distribution collected in the MA-PMT the authors are able to determine depth of interaction (DOI), thus making the proper identification of lines of response (LORs) with large incidence angles possible. PET performances are compared with those obtained with currently commercially available small animal PET scanners. RESULTS: At axial center when the point-like source is located at 5 mm from the radial center, the spatial resolution measured was 1.65, 1.80, and 1.86 mm full width at half maximum (FWHM) for radial, tangential, and axial image profiles, respectively. A system scatter fraction of 7.5% (mouse-like phantom) and 13% (rat-like phantom) was obtained, while the maximum noise equivalent count rate (NECR) was 16.9 kcps at 12.7 MBq (0.37 MBq/ml) for mouse-like phantom and 12.8 kcps at 12.4 MBq (0.042 MBq/ml) for rat-like phantom The peak absolute sensitivity in the center of the FOV is 2% for a 30% peak energy window. Several animal images are also presented. CONCLUSIONS: The overall performance of our small animal PET is comparable to that obtained with much more complex crystal pixelated PET systems. Moreover, the new proposed PET produces high-quality images suitable for studies with small animals.

Design and evaluation of the MAMMI dedicated breast PET.

PURPOSE: A breast dedicated positron emission tomography (PET) scanner has been developed based on monolithic LYSO crystals coupled to position sensitive photomultiplier tubes (PSPMTs). In this study, we describe the design of the PET system and report on its performance evaluation. METHODS: MAMMI is a breast PET scanner based on monolithic LYSO crystals. It consists of 12 compact modules with a transaxial field of view (FOV) of 170 mm in diameter and 40 mm axial FOV that translates to cover up to 170 mm. The patient lies down in a prone position that facilitates maximum breast elongation. Quantitative performance analysis of the calculated method for the attenuation correction specifically developed for MAMMI, and based on PET image segmentation, has also been conducted in this evaluation. In order to fully determine the MAMMI prototype's performance, we have adapted the measurements suggested for National Electrical Manufacturers Association (NEMA) NU 2-2007 and NU 4-2008 protocol tests, as they are defined for whole-body and small animal PET scanners, respectively. RESULTS: Spatial resolutions of 1.6, 1.8, and 1.9 mm were measured in the axial, radial, and tangential directions, respectively. A scatter fraction of 20.8% was obtained and the maximum NEC was determined to be 25 kcps at 44 MBq. The average sensitivity of the system was observed to be 1% for an energy window of (250 keV-750 keV) and a maximum absolute sensitivity of 1.8% was measured at the FOV center. CONCLUSIONS: The overall performance of the MAMMI reported on this evaluation quantifies its ability to produce high quality PET images. Spatial resolution values below 3 mm were measured in most of the FOV. Only the radial component of spatial resolution exceeds the 3 mm at radial positions larger than 60 mm. This study emphasizes the need for standardized testing methodologies for dedicated breast PET systems similar to NEMA standards for whole-body and small animal PET scanners.

Monitoring system for isolated limb perfusion based on a portable gamma camera.

BACKGROUND: The treatment of malignant melanoma or sarcomas on a limb using extremity perfusion with tumour necrosis factor (TNF-alpha) and melphalan can result in a high degree of systemic toxicity if there is any leakage from the isolated blood territory of the limb into the systemic vascular territory. Leakage is currently controlled by using radiotracers and heavy external probes in a procedure that requires continuous manual calculations. The aim of this work was to develop a light, easily transportable system to monitor limb perfusion leakage by controlling systemic blood pool radioactivity with a portable gamma camera adapted for intraoperative use as an external probe, and to initiate its application in the treatment of MM patients. METHODS: A special collimator was built for maximal sensitivity. Software for acquisition and data processing in real time was developed. After testing the adequacy of the system, it was used to monitor limb perfusion leakage in 16 patients with malignant melanoma to be treated with perfusion of TNF-alpha and melphalan. RESULTS: The field of view of the detector system was 13.8 cm, which is appropriate for the monitoring, since the area to be controlled was the precordial zone. The sensitivity of the system was 257 cps/MBq. When the percentage of leakage reaches 10% the associated absolute error is +/-1%. After a mean follow-up period of 12 months, no patients have shown any significant or lasting side-effects. Partial or complete remission of lesions was seen in 9 out of 16 patients (56%) after HILP with TNF-alpha and melphalan. CONCLUSION: The detector system together with specially developed software provides a suitable automatic continuous monitoring system of any leakage that may occur during limb perfusion. This technique has been successfully implemented in patients for whom perfusion with TNF-alpha and melphalan has been indicated.

[Importance of the antimicrobial spectrum and the bacterial resistances in the antibiotic choice for the treatment of pediatric patients with communitary infections]. / Importancia de la cobertura antimicrobiana y de las resistencias bacterianas en la elección de antibióticos en Pediatría.

OBJECTIVE: This study aimed to know the importance of the antimicrobial spectrum and the bacterial resistances for the antibiotic choice in the extrahospitalary pediatric area, at the same time that establish the relationship with others therapeutics parameters. MATERIAL AND METHODS: Cross-sectional, observational study within the MUSA (Improvement of Use of Antimicrobial Agents in Primary Health Care) Project made by personal interview of 210 pediatrician doctors randomly selected with national representation. This target is included in a bigger universe (855 doctors) representative of the most doctors responsible of the antibiotic prescriptions in the extrahospitalary area (sample error of the 3.3% for a 95% confidence interval and maximum response dispersion: p=q=50). The results of the pediatric study were subjected to a comparative analysis with the results of a similar study made ten years ago and with the global results of the general study. The questionnaire used for the interview had two clearly different parts: in the first part, the questions were open with the objective to get spontaneous answers from the participants; the second part had questions with suggested answers. RESULTS: Clinical efficacy is the most spontaneously valued issue by the Spanish pediatricians when it comes to choosing an antimicrobial agent; efficacy is followed by tolerance/safety and posology. Antimicrobial spectrum is mentioned by one out of 4-5 pediatricians that have participated in the study (21.9%), while the bacterial resistances are only mentioned by a 3.8%. In a suggested level, clinical efficacy is still the most valued parameter, being identified by 7 out of 10 interviewed with the bacterial eradication. In this case, the antimicrobial spectrum is the following parameter on significance, appearing as a synonym of "activity against specific microorganisms" in 2 out of 3 cases. In relation to his own evaluation, 3 out of 4 pediatricians say they take "a lot" of the bacterial resistances into consideration, who are mostly understood as "global rate" for 5-6 out of 10 interviewed, whether the resistance showed by the pneumococcal is what worried the most to 4 out of 10 of them. This importance given to the bacterial resistances at the second part of the study contrasts with the low consideration showed when it is compared with other parameters and the valoration is treated in a spontaneous way. In relation to a similar study realized on 1997 (Urano Proyect), we observe that clinical efficacy has replaced tolerance/safety as a parameter to bear in mind, probably as a consequence of more experience and confidence with the most important antimicrobial agents in the antibiotic prescriptions in podiatry. On the other hand, the bacterial resistances still being left out on the pediatricians spontaneous consideration, a fact that is shared with the majority of the collectives participating on the general study. The rest of the parameters stay in a similar way. CONCLUSIONS: Is necessary to emphasize at the importance of bacterial resistances in the antimicrobials rational use on the pediatric patient. As the antimicrobial tolerance profile has been improving in the last ten years, clinical efficacy, understood as "bacterial eradication" has became the most determining parameter when choosing antimicrobial agents.

[Behavior of the primary care physicians in the treatment of community infections]. / Comportamiento de los médicos de Atención Primaria en el tratamiento de las infecciones comunitarias.

This study aimed to evaluate the behavior of the physicians who attend to patients with community infections who are responsible for most of the antibiotic prescriptions made in the community setting. Furthermore, the evolution over the last 10 years in regards to the treatment habits of the most frequent infections in Primary Health Care (PHC) was studied and prescription behaviors were analyzed in relationship to the acquaintance and attitude of the participating physicians. A data collection sheet from 1,411 prescriptions made by 855 physicians from different specialties was used to conduct the study. This represents a statistically significant sample nationwide both from the point of view of the physicians involved in the treatment of infectious diseases in PHC as well as regarding to the prescriptions they have written. The study reveals the amplitude of respiratory and pararespiratory disease with oral antimicrobial agents, particularly beta-lactamics, and the significant advance in the last 10 years in the use of amoxicillin and clavulanic acid as treatment of choice. Treatment duration was somewhat longer while the number of containers prescribed was less than in the previous study. This would be related to the use of more spaced doses of the antimicrobial agents. Furthermore, the study reveals some discrepancies between attitudes and events of the physicians in the approach to certain diagnoses. Key words: Behavior. Primary care physicians. Prescription. Antimicrobials agents.

[Antimicrobial selection criteria evaluation by family doctors and general practitioners]. / Evaluación de los criterios de selección de antimicrobianos por los médicos generales y de familia.

OBJECTIVE: This study has aimed to know the criteria used by the Spanish medical practitioners/family doctors (MP/FD) when choosing an antimicrobial agent in their daily practice and to compare it with that existing one decade ago. MATERIAL AND METHODS: This is an observational, cross-sectional study performed with a structured personal interview to 450 MP/FDs randomly chosen with representativeness on the national level. The field work was made by specialized personnel in the last quarter of the year 2006. A 95.5% confidence interval margin was proposed, with a sample error = 4.7%, for maximum dispersion response (p=q=50). RESULTS: The parameter considered most when choosing an antibiotic treatment (spontaneous response) is clinical efficacy (two out of every three doctors). Clinical efficacy is following by the dosage regime and tolerability/safety, which was the principal parameter expressed ten years ago. Following these are antibacterial spectrum, administration route, price and bacterial resistances. However, they considered that the latter significantly influence clinical efficacy and when they are not relativized with other parameters, the doctors state that they take them into account <>. It seems that the opinion of the patient is usually considered and that the protocol, scientific information and expert's opinions are the principal sources of information considered when prescribing an antimicrobial agent. Amoxicillin/clavulanate is the antibiotic drug of choice in all upper and lower respiratory tract infections. There is overestimation of the bacterial etiology in throat infections and acute bronchitis and S. pyogenes to betalactamic antibiotics. It is concluded that knowledge of the Spanish MP/DF regarding antimicrobial therapy has improved in recent years and that clinical efficacy, related with bacterial eradication and not only with clinical remission, is the factor that should be considered when choosing an antibiotic.

[Knowledge and attitude of primary health care doctors in the treatment of community-acquired infections]. / Conocimiento y actitud de los médicos de atención primaria en el tratamiento de las infecciones comunitarias.

The aim of this study was to evaluate the knowledge and attitude of the doctors who attend patients with community-acquired infections and who are responsible for most of the antibiotic prescriptions in primary health care. At the same time, the evolution experienced in the last ten years in relation to the main parameters analyzed was studied. The study was conducted by personal interviews, using a structured questionnaire, administered to 855 doctors of different specialties, who make up a statistically significant nationwide sample. The study showed that in spite of the improvements in the knowledge of the microbiology of infectious diseases and the choice of antimicrobial agents, there are still certain areas that need improvement. These are, above all, in regard to the bacterial resistance problem, underevaluation of the viral etiology of certain respiratory tract infections and the somewhat condescending attitude with "visits by third parties", indulgence prescriptions and therapeutic noncompliance. Efficacy defined not only as clinical remission but also, and essentially, as antibacterial coverage, are the main parameters considered when participating physicians choose an antibiotic.

[Storage of antibiotics in Spanish households]. / Almacenamiento de antibioticos en los hogares espanoles.

This study aimed to determine how many antibiotics were stored in Spanish households, analyzing their origin and characteristics (number, antibiotic type and pharmaceutical form). In addition, some general characteristics of the "home medicine cabinet" were investigated. The study was conducted by telephone interviews with one of the heads of the family in 1,000 randomly chosen Spanish homes, but in accordance with a territorial distribution proportional to the Spanish population and to the urban and rural setting. According to the results obtained, there was at least one antibiotic packet in 37% of Spanish households, mostly corresponding (96.5%) to broad-spectrum semisynthetic penicillin (amoxycillin or clavulanic-amoxycillin). A total of 59.2% of the packets found corresponded to solid oral forms (tablets, capsules, etc.) and 40.4% corresponded to liquid oral forms (syrup, suspension, sachet). The antibiotics were mostly obtained by medical prescription (84.9%), self-medication being the origin in almost 15% of them. There was a member of the family under antibiotic treatment at the time of the study in only 30% of the households that had one or more containers. The financial evaluation of the "leftover" antibiotic doses makes it possible to estimate a cost of about 18 million euros, more than 12 million of which would have been financed by the Health Care Administration. The results show that storing of antibiotics continues to be important in Spain, even though a considerable decrease has been observed in the last 10 years. This could be related to a progressive abandonment of self-medicating attitudes.

[Effect of anti-inflammatory drugs, alone and combined with ofloxacin, on the respiratory burst of human polymorphonuclear leukocytes]. / Efecto de los antiinflamatorios, solos y asociados con ofloxacino, en la explosión respiratoria de los leucocitos polimorfonucleares humanos.

The antibacterial activity of polymorphonuclear leukocytes (PMNs) is based on the production of superoxide anion and H(2)O(2) in the respiratory burst and can be impaired in different ways. The combination of an antibacterial agent and an antiinflammatory drug is quite common in immunodepressed patients whose respiratory burst of PMN could be impaired. In this study we examine in vitro the effect of pretreating (35 degrees C for 30 min) PMNs with the antiinflammatory drugs dexamethasone (0.4, 4 and 40 microgram/ml), methylprednisolone (0.37, 3.7 and 37 microgram/ ml), hydrocortisone (0.048, 0.48 and 4.8 microgram/ml), betamethasone (0.1, 1, 5 and 10 mg/ml), phenylbutazone (1000 microgram/ml) and acetylsalicylic acid (25, 250, 2500 microgram/ml) alone, and combined with 10 mg/ml of ofloxacin on the respiratory burst. Superoxide anion was measured by the cytochrome c reduction microtechnique and H(2)O(2) by phenol red. The antiinflammatory drugs alone decreased the production of H(2)O(2) (except dexamethasone and methylprednisolone) and superoxide anion (except betamethasone) from 15-45%, depending on the antiinflammatory drug and concentration, while ofloxacin increased the production of superoxide anion (20.2 +/- 6.7%). The combination of antiinflammatory drugs with ofloxacin neutralizes the inhibitory effect of the former on the respiratory burst of PMNs. It is therefore important to know the effect of drugs on the respiratory burst in order to choose those that have the same therapeutic effect without interfering with PMN functions.

[Effect of fluconazole and itraconazole on human polymorphonuclear leukocyte oxidative metabolism and phagocytosis]. / Efectos del itraconazol y el fluconazol sobre el metabolismo oxidativo y la capacidad fagocítica de los leucocitos polimorfonucleares.

The effect of pretreatment of human polymorphonuclear leukocites (PMNs), for 30 min with fluconazole (0.1, 1, 5 and 50 microgram/ml) and itraconazole (0.05, 0.5 and 5 microgram/ml) on phagocytosis and generation of free radicals (superoxide anion and hydrogen peroxide) was studied in vitro. Phorbol miristate acetate (200 nM) was used as a stimulant. The mean amount of superoxide anion generated by 2.5 x 10(5) PMNs per hour was 4.39 +/- 1.13 nmol for fluconazole-treated PMNs and 4.56 +/- 1.2 nmol for itraconazole, and that of hydrogen peroxide was 11.19 +/- 2.18 and 11.28 +/- 3.61 nmol, respectively. The phagocytosis percentages were 83.8% for the control group and 88. 7% in antifungal agent- treated PMNs; the phagocytosis index was 3.0 yeasts per PMN for both groups. The differences between the control and treated PMNs were not statistically significant at any of the tested concentrations.

[In vitro activity of posaconazole against yeasts isolated in blood cultures]. / Actividad in vitro de posaconazol frente a levaduras aisladas en hemocultivo.

The in vitro activity of posaconazole against Candida species isolated from blood cultures and the influence of incubation time was studied and compared with that of fluconazole. A total of 112 isolates were studied: 32 Candida albicans, 33 C. parapsilosis, 17 C. tropicalis, 8 C. glabrata, 8 C. guilliermondii, 3 C. famata, 2 C. lusitaniae, 1 C. lipolytica, 1 C. inconspicua, 1 C. lambica, 3 Saccharomyces cerevisiae, 1 Blastoschizomyces capitatus, 1 Geotricum spp. and 1 Pichia omheri. The MIC was obtained using the M27-A microdilution method described by the NCCLS for Candida spp. and Cryptococcus neoformans. The species most susceptible to posaconazole were C. parapsilosis (MCI90 0.016 mg/l), C. guilliermondii (MIC90 0.12 mg/l), C. glabrata (MCI90 0.5 mg/l) and Candida spp. (MCI90 0.25 mg/l). However, this azole did not improve the activity of fluconazole against C. tropicalis (MIC90 8 mg/l) and C. albicans (MCI90 mg/l). The time of reading was important in the detection of resistance, as the number of strains resistant to fluconazole or posaconazole was higher at 48 hours than at 24 hours for C. albicans and C. tropicalis. All the other species of Candida were susceptible at both reading times.

[Influence of ion pump-inhibiting drugs on the accumulation of ofloxacin and grepafloxacin in human polymorphonuclear leukocytes]. / Influencia de fármacos inhibidores de bombas de iones en la acumulación de ofloxacino y grepafloxacino en el interior de los leucocitos polimorfonucleares humanos.

In this study we tested the influence of three ion pump-inhibiting drugs (digoxin, omeprazole and verapamil) on the accumulation of ofloxacin and grepafloxacin in human polymorphonuclear leukocytes. Two assay conditions were established: cell preincubation with the drug for 30 or 60 minutes before addition of quinolone, or addition of both drugs simultaneously. The maximum I/E for ofloxacin is different depending on the assay conditions: 7.69+/-0.88; 5.64+/-1.91 and 3.56+/-1.04 for the assay without preincubation and with preincubation for 30 or 60 minutes at 37 masculine C, respectively. Similarly, grepafloxacin reached the following maximums: 61.27+/-3.04; 32.18+/-3.25 and 22.52+/-3.86. Digoxin did not significantly modify the accumulation of the quinolones, but it increased the I/E compared with the control. In general, omeprazole reduced the accumulation of both quinolones. When omeprazole and ofloxacin were added together, ofloxacin's I/E was significantly lower; however, for grepafloxacin, 60 minutes of preincubation were necessary. Verapamil induced a significant increase in the I/E for both quinolones when the cells were preincubated at 10 times the plasma concentration.

[In vitro activity of fluconazole against Candida albicans isolated from blood culture]. / Actividad in vitro de fluconazol sobre Candida albicans aisladas de hemocultivo.

The in vitro activity of fluconazole against 65 Candida albicans isolated from blood culture in 1995, 1996 and 1997 was studied by macrodilution and disk diffusion methods. The MIC ranged from 0.03 to 64 microg/ml, with 93.6% of strains being inhibited with 1 microg/ml fluconazole; the mode MIC was 0.25 microg/ml. Using this method, only one strain was resistant and another was susceptible depending on the dose. By diffusion, eight strains were susceptible, 53 intermediate, and four resistant. The strains susceptible by dilution were also susceptible by diffusion, but the strains resistant by diffusion were not always resistant by dilution. We find it therefore useful to determine the MIC of fluconazole to the C. albicans resistant by diffusion.

[Effect of antiinflammatory agents on the accumulation of ofloxacin in human polymorphonuclear leukocytes]. / Influencia de los antiinflamatorios en la acumulación de ofloxacino en el interior de los leucocitos polimorfonucleares humanos.

The uptake of quinolones is a recently defined pharmacokinetic parameter which is increasing in importance in clinical practice, especially for immunocompromised patients whose polymorphonuclear leukocytes (PMNLs) have their bactericidal systems impaired, or in infections due to bacteria able to survive in the phagocytes. In both situations, antibiotics able to penetrate and be active in the phagocytes are required. The simultaneous administration of an antibiotic and an antiinflammatory drug is frequent, and previous studies have described interactions between the intracellular activity of the quinolones and the presence of phenylbutazone. We studied the effect of the presence of and the pretreatment (37 C for 30 and 60 min) of human PMNLs with the antiinflammatory drugs betamethasone (1 mg/l), hydrocortisone (1 mg/l), phenylbutazone (10 mg/ml), and acetylsalicylic acid (200 mg/l) on the uptake of ofloxacin (10 mg/l) by the PMNLs using a fluorometric method to measure the intra-PMNL concentration of ofloxacin. The presence of betamethasone did not modify the uptake of ofloxacin by PMNLs. Pretreatment of PMNLs with hydrocortisone, phenylbutazone and acetylsalicylic acid produced a significant decrease in the maximum intracellular concentration/extracellular concentration ratios compared with the maximum reached without pretreatment. These results suggest that hydrocortisone, phenylbutazone and acetylsalicylic acid interfere with the uptake of ofloxacin by PMNLs and increase the efflux of ofloxacin from PMNLs.

[Antibiotics in Spanish households. Medical and socioeconomic implications. URANO Study Group]. / Antibióticos en los hogares españoles. Implicaciones médicas y socioeconómicas. Grupo de Estudio del Uso Racional de los Antibióticos Orales (URANO).

BACKGROUND: To determine the storage of antibiotics in Spanish households and to analyse its source. POPULATION AND METHODS: Quantitative study carried out by telephone interview with housewives or head of the family members in 1,000 households that have been chosen at random and by agreement with a proportion of the territorial distribution of the Spanish population. RESULTS: In 42% of households that have been approached, one (88.1%) or more antibiotic packets were present, being a result of a doctor's prescription in two thirds of cases. In most cases (71.9%) amoxycillin was the antibiotic found. Concerning the pharmaceutical forms, 55% corresponded to solid oral (pills, tablets, capsules), 45% liquid oral forms (syrups, suspensions, sachets), whereas parenteral vials were not identified. Only in the 19% of households with antibiotic packets (8% of the total) there was a member of the family under antibiotic treatment. The economic evaluation of the non administrated antibiotic doses, present in households was about 5,000 millions pesetas. Over 3,000 millions pesetas had been financed by Health Public Administration. CONCLUSIONS: The storage of antibiotics in households is an important factor which increments the cost, reduces the efficiency and decreases the quality of the antibiotic treatment at the community level.

Neuralgia lagrimal recurrente desencadenada por procedimientos oftalmológicos / Recurrent lacrimal neuralgia secondary to ophthalmological procedures

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Expectation maximization (EM) algorithms using polar symmetries for computed tomography (CT) image reconstruction.

We suggest a symmetric-polar pixellation scheme which makes possible a reduction of the computational cost for expectation maximization (EM) iterative algorithms. The proposed symmetric-polar pixellation allows us to deal with 3D images as a whole problem without dividing the 3D problem into 2D slices approach. Performance evaluation of each approach in terms of stability and image quality is presented. Exhaustive comparisons between all approaches were conducted in a 2D based image reconstruction model. From these 2D approaches, that showing the best performances were finally implemented and evaluated in a 3D based image reconstruction model. Comparison to 3D images reconstructed with FBP is also presented. Although the algorithm is presented in the context of computed tomography (CT) image reconstruction, it can be applied to any other tomographic technique as well, due to the fact that the only requirement is a scanning geometry involving measurements of an object under different projection angles. Real data have been acquired with a small animal (CT) scanner to verify the proposed mathematical description of the CT system.

ALBIRA: a small animal PET∕SPECT∕CT imaging system.

PURPOSE: The authors have developed a trimodal PET∕SPECT∕CT scanner for small animal imaging. The gamma ray subsystems are based on monolithic crystals coupled to multianode photomultiplier tubes (MA-PMTs), while computed tomography (CT) comprises a commercially available microfocus x-ray tube and a CsI scintillator 2D pixelated flat panel x-ray detector. In this study the authors will report on the design and performance evaluation of the multimodal system. METHODS: X-ray transmission measurements are performed based on cone-beam geometry. Individual projections were acquired by rotating the x-ray tube and the 2D flat panel detector, thus making possible a transaxial field of view (FOV) of roughly 80 mm in diameter and an axial FOV of 65 mm for the CT system. The single photon emission computed tomography (SPECT) component has a dual head detector geometry mounted on a rotating gantry. The distance between the SPECT module detectors can be varied in order to optimize specific user requirements, including variable FOV. The positron emission tomography (PET) system is made up of eight compact modules forming an octagon with an axial FOV of 40 mm and a transaxial FOV of 80 mm in diameter. The main CT image quality parameters (spatial resolution and uniformity) have been determined. In the case of the SPECT, the tomographic spatial resolution and system sensitivity have been evaluated with a (99m)Tc solution using single-pinhole and multi-pinhole collimators. PET and SPECT images were reconstructed using three-dimensional (3D) maximum likelihood and ordered subset expectation maximization (MLEM and OSEM) algorithms developed by the authors, whereas the CT images were obtained using a 3D based FBP algorithm. RESULTS: CT spatial resolution was 85 µm while a uniformity of 2.7% was obtained for a water filled phantom at 45 kV. The SPECT spatial resolution was better than 0.8 mm measured with a Derenzo-like phantom for a FOV of 20 mm using a 1-mm pinhole aperture collimator. The full width at half-maximum PET radial spatial resolution at the center of the field of view was 1.55 mm. The SPECT system sensitivity for a FOV of 20 mm and 15% energy window was 700 cps∕MBq (7.8 × 10(-2)%) using a multi-pinhole equipped with five apertures 1 mm in diameter, whereas the PET absolute sensitivity was 2% for a 350-650 keV energy window and a 5 ns timing window. Several animal images are also presented. CONCLUSIONS: The new small animal PET∕SPECT∕CT proposed here exhibits high performance, producing high-quality images suitable for studies with small animals. Monolithic design for PET and SPECT scintillator crystals reduces cost and complexity without significant performance degradation.