The level of dental fear and anxiety is higher in children with both severe Molar-Incisor Hypomineralisation and active dental caries lesions compared to children without these conditions.

PURPOSE: To assess levels of dental fear and anxiety (DFA) in children with and without Molar-Incisor Hypomineralisation (MIH) and dental caries lesions. METHODS: In this cross-sectional observational study, 159 children between 8 and 12 years of age were included. For the evaluation of DFA, children responded to the validated version of the Children's Fear Survey Schedule-Dental Subscale. MIH was assessed using the MIH Index. To evaluate the activity of dental caries lesions and dental caries experience, the Nyvad criterion and the dmft/DMFT index were used, respectively. Dental hypersensitivity was evaluated using air stimulation and a Visual Analogue Scale. The association between MIH and dental caries with DFA was assessed using the generalised linear model with Poisson family, identity link function and robust variance estimation. The significance level was set at 5%. RESULTS: The mean DFA score was 28.3 (SD = 13.4) with scores ranging from 15 to 64. Amongst children presenting both MIH and dental caries, the perception of DFA was notably higher compared to those with either MIH or dental caries alone. The activity of caries lesion in patients with MIH also influenced DFA levels (diff: 18.6; 95% CI: 12.0-25.2; p < 0.001). Dental caries experience in the primary dentition also demonstrated statistical significance concerning DFA (95% CI: 0.8-13.3; p value = 0.027). CONCLUSION: Children with MIH exhibit higher levels of DFA than children without MIH. The experience of dental caries and the activity of caries lesions significantly influence the perception of DFA in children with MIH.

Translation and transcultural adaptation of the AS-20 scale to measure quality of life in adults with strabismus in Colombia, a pilot study.

BACKGROUND: Strabismus generates a negative psychosocial impact on adult patients, affecting aspects such as self-perception and quality of life. There is no scale in Colombian Spanish that measures these impacts. OBJECTIVE: To carry out the translation and cross-cultural adaptation of the AS-20 instrument into Colombian Spanish. MATERIALS AND METHODS: Pilot test of a cross-sectional Study for the translation, reverse translation, and cross-cultural the AS-20 instrument from its original language, English, to Colombian Spanish, in adult patients with strabismus in Bogotá, Colombia. RESULTS: 16 patients were assessed. The age range was between 18 and 68 years with a mean age of 41 years. The scale was answered in an average time of 10.62min. Difficulty was reported in three individuals for understanding two items (questions 8 and 14), which were resolved. CONCLUSION: The translation and pilot test of AS-20 scale into Colombian Spanish was carried out, identifying and solving translational difficulties. Is the first step in the cross-cultural adaptation process. Based on the results, the validation and cross-cultural adaptation can be completed in a future study.

Microbiological Profile, Prevalence, and Characterization of Salmonella enterica in Peanuts, Pecans, Raisins, Sun-Dried Tomatoes, and Chocolate Sprinkles Sold in Bulk in Markets in Querétaro, Mexico.

ABSTRACT: In Mexico, the prevalence of Salmonella enterica in low-water-activity foods and its link to outbreaks are unknown. The aim of this study was to determine the microbiological profile and the prevalence of S. enterica in several low-water-activity foods, including peanuts, pecans, raisins, sun-dried tomatoes, and chocolate sprinkles, purchased in retail establishments in Querétaro, Mexico. Seventy samples of each food item sold in bulk were purchased. Aerobic plate count, molds, yeasts, total coliforms, Escherichia coli, and Staphylococcus aureus were quantified in 10-g samples. The prevalence of S. enterica in 25-g samples was determined. From positive samples, S. enterica isolates (60) were characterized based on their antimicrobial susceptibility to 14 antibiotics, the presence-absence of 13 virulence genes, and serotype. The concentration of aerobic plate count, molds, yeasts, total coliforms, and E. coli ranged from 3.1 to 5.2 log CFU g-1, from 2.0 to 2.4 log CFU g-1, from 2.0 to 3.0 log CFU g-1, from 0.6 to 1.1 log most probable number (MPN) g-1, and from 0.5 to 0.9 log MPN g-1, respectively. S. aureus was not detected in any sample (<10 CFU g-1). The prevalence of S. enterica in chocolate sprinkles, raisins, peanuts, pecans, and sun-dried tomatoes was 26, 29, 31, 40, and 52%, respectively. Most isolates (68.3%) were resistant to at least one antibiotic. Chromosome-associated virulence genes were found in all isolates, and only one strain had sopE, and 98.3% of the isolates were grouped in the same virulotype. Among the isolates, the most frequent serotype was Tennessee (51 of 60). According to the characteristics evaluated, we grouped the isolates into 24 clusters. The elevated prevalence of S. enterica highlights the role of low-water-activity food items sold in bulk at markets as potential vehicles for pathogen transmission. Regardless of the low variability among S. enterica isolates, their characterization could be helpful to elucidate which strains are circulating in these foods for improving epidemiological surveillance.

Changes in air quality in Mexico City, London and Delhi in response to various stages and levels of lockdowns and easing of restrictions during COVID-19 pandemic.

The impacts of COVID-19 lockdown restrictions have provided a valuable global experiment into the extent of improvements in air quality possible with reductions in vehicle movements. Mexico City, London and Delhi all share the problem of air quality failing WHO guideline limits, each with unique situations and influencing factors. We determine, discuss and compare the air quality changes across these cities during the COVID-19, to understand how the findings may support future improvements in their air quality and associated health of citizens. We analysed ground-level PM10, PM2.5, NO2, O3 and CO changes in each city for the period 1st January to August 31, 2020 under different phases of lockdown, with respect to daily average concentrations over the same period for 2017 to 2019. We found major reductions in PM10, PM2.5, NO2 and CO across the three cities for the lockdown phases and increases in O3 in London and Mexico City but not Delhi. The differences were due to the O3 production criteria across the cities, for Delhi production depends on the VOC-limited photochemical regime. Levels of reductions were commensurate with the degree of lockdown. In Mexico City, the greatest reduction in measured concentration was in CO in the initial lockdown phase (40%), in London the greatest decrease was for NO2 in the later part of the lockdown (49%), and in Delhi the greatest decrease was in PM10, and PM2.5 in the initial lockdown phase (61% and 50%, respectively). Reduction in pollutant concentrations agreed with reductions in vehicle movements. In the initial lockdown phase vehicle movements reduced by up to 59% in Mexico City and 63% in London. The cities demonstrated a range of air quality changes in their differing geographical areas and land use types. Local meteorology and pollution events, such as forest fires, also impacted the results.

[Reversible cerebral vasoconstriction syndrome secondary to secreting jugular paraganglioma]. / Sindrome de vasoconstriccion cerebral reversible secundario a un paraganglioma yugular secretor de metanefrinas.

TITLE: Sindrome de vasoconstriccion cerebral reversible secundario a un paraganglioma yugular secretor de metanefrinas.

Risk scores for type 2 diabetes mellitus in Latin America: a systematic review of population-based studies.

AIM: To summarize the evidence on diabetes risk scores for Latin American populations. METHODS: A systematic review was conducted (CRD42019122306) looking for diagnostic and prognostic models for type 2 diabetes mellitus among randomly selected adults in Latin America. Five databases (LILACS, Scopus, MEDLINE, Embase and Global Health) were searched. type 2 diabetes mellitus was defined using at least one blood biomarker and the reports needed to include information on the development and/or validation of a multivariable regression model. Risk of bias was assessed using the PROBAST guidelines. RESULTS: Of the 1500 reports identified, 11 were studied in detail and five were included in the qualitative analysis. Two reports were from Mexico, two from Peru and one from Brazil. The number of diabetes cases varied from 48 to 207 in the derivations models, and between 29 and 582 in the validation models. The most common predictors were age, waist circumference and family history of diabetes, and only one study used oral glucose tolerance test as the outcome. The discrimination performance across studies was ~ 70% (range: 66-72%) as per the area under the receiving-operator curve, the highest metric was always the negative predictive value. Sensitivity was always higher than specificity. CONCLUSION: There is no evidence to support the use of one risk score throughout Latin America. The development, validation and implementation of risk scores should be a research and public health priority in Latin America to improve type 2 diabetes mellitus screening and prevention.

Molar Incisor Hypomineralization in Colombia: Prevalence, Severity and Associated Risk Factors.

Aim: To determine prevalence, severity, and risk factors associated with Molar Incisor Hypomineralization (MIH) in schoolchildren between 6 and 15 years of age in Medellin, Colombia. Study design: We conducted a retrospective observational study including 1.075 children born and residing in Medellin, Colombia. A structured questionnaire addressing gestational period and first three years of child's life was administered to biological mothers. Two calibrated examiners established MIH diagnosis following the European Academy of Paediatric Dentistry criteria. Data were analyzed using descriptive statistics, bivariate analysis, and linear regression with a 5% significance. Results: Study population was predominantly male (70.7%), average age was 9.3±1.9 years. Prevalence of MIH was 11,2%. The majority of defects (85%) were mild. MIH was associated with alterations during last gestational trimester, type of childbirth and respiratory problems. Conclusion. MIH prevalence in schoolchildren between 6 and 15 years of age was 11.2%, being mild defects more frequently found. MIH was associated with different factors during pregnancy and the first three years of life.

[Reversible cerebral vasoconstriction syndrome associated with anastrozole: an unusual cause of high impact]. / Sindrome de vasoconstriccion cerebral reversible asociado a anastrozol: una causa inusual de alto impacto.

INTRODUCTION: Reversible cerebral vasoconstriction syndrome (RCVS) is a low incidence disability with a multifactorial etiology and a wide array of symptoms. The main symptom is a thunderclap headache, accompanied sometimes with various neurological deficits that can lead to death. RCVS is usually diagnosed through radiological imaging technology. The treatment includes adopting general measures of monitoring, symptomatic management, identifying the etiology and acting on it to avoid recurrence. CASE REPORT: A 71-year-old woman with a history of breast cancer originally treated with tamoxifen. Due to urticaria, the anastrozole management was staggered. She was admitted for aphasia, drowsiness and a thunderclap headache. The patient reported a similar event two weeks prior admission. In brain resonance, there was evidence of small sub-arachnoidal haemorrhage (SAH) of the left parietal temporal convexity and cerebral angiography. As well as documented vasospasm in the posterior parietal region confirming the diagnosis of RCVS plus SAH. During the stay, she presented three events with the same characteristics, requiring intensive monitoring and two therapeutic panangiographies with intra-arterial nimodipine with subsequent resolution of the vessel spasm. The patient remains asymptomatic six months later. CONCLUSION: RCVS is difficult to diagnose given its wide array of symptoms and multifactorial etiology. In this case, RCVS plus SAH is associated with the use of anastrozole. So far there are no reported cases of aromatase inhibitors associated with this pathology and should be reported in the literature for pharmacovigilance.

TITLE: Sindrome de vasoconstriccion cerebral reversible asociado a anastrozol: una causa inusual de alto impacto.Introduccion. El sindrome de vasoconstriccion cerebral reversible (SVCR) es una entidad de baja incidencia, de etiologia multifactorial y amplio espectro de presentacion. El principal sintoma es la cefalea de tipo trueno. Puede estar acompañado de focalizacion neurologica y cursar con desenlaces clinicos variable que incluso pueden llevar a la muerte. El diagnostico es clinico e imaginologico, y el tratamiento incluye adoptar medidas generales de monitorizacion, manejo sintomatico, identificar la etiologia y actuar sobre ella para evitar recurrencia. Caso clinico. Mujer de 71 años con antecedente de cancer de seno, tratada inicialmente con tamoxifeno; por presentar urticaria, se escalono tratamiento con anastrozol. Ingreso por cefalea de tipo trueno, afasia anterior y somnolencia. La paciente refirio un evento similar una semana antes del ingreso. En la resonancia magnetica cerebral evidencio una hemorragia subaracnoidea (HSA) pequeña de la convexidad temporoparietal izquierda, y la panangiografia documento vasoespasmo en la region parietal posterior, lo que confirmo el diagnostico de SVCR mas HSA. Durante el ingreso presento tres eventos de iguales caracteristicas, que requirieron monitorizacion intensiva y dos panangiografias terapeuticas con nimodipino intraarterial, con posterior resolucion del vasoespasmo. Permanece asintomatica seis meses despues. Conclusion. El SVCR constituye un reto diagnostico dada su presentacion variable y su etiologia multifactorial. En este caso, el SVCR mas HSA esta asociado al uso de anastrozol. Hasta el momento no hay casos descritos de inhibidores de la aromatasa asociados a esta patologia, que debe comunicarse para su farmacovigilancia.

A comprehensive analysis of factors related to carmustine/bevacizumab response in recurrent glioblastoma.

PURPOSE: Patients with recurrent glioblastoma (rGBM) have a poor prognosis, with survival ranging from 25 to 40 weeks. Antiangiogenic agents are widely used, showing a variable response. In this study, we explored the efficacy of carmustine plus bevacizumab (BCNU/Bev) for treating rGBM. METHODS/PATIENTS: In this study, we assessed 59 adult patients with histologically confirmed rGBM who were treated with BCNU/Bev as second-line regimen. The response rate (RR), progression-free survival (PFS) and overall survival (OS) were evaluated according to their molecular expression profile, including CD133 mRNA expression, MGMT methylation (pMGMT), PDGFR amplification, YKL40 mRNA expression, IDH1/2 condition, p53 and EGFRvIII mutation status. RESULTS: Median follow-up was 18.6 months, overall RR to the combination was 56.3%, and median PFS was 9.0 months (95% CI 8.0-9.9). OS from time of diagnosis was 21.0 months (95% CI 13.2-28.7) and from starting BCNU/Bev it was 10.7 months (95% CI 9.5-11.8). IDH1/2 mutations were found in 30.5% of the patients, pMGMT in 55.9% and high CD133 mRNA expression in 57.6%. Factors which positively affected PFS included performance status (p = 0.015), IDH+ (p = 0.05), CD133 mRNA expression (p = 0.009) and pMGMT+ (p = 0.007). OS was positively affected by pMGMT+ (p = 0.05). Meanwhile, YKL40 negatively affected PFS (p = 0.01) and OS (p = 0.0001). Grade ≥ 3 toxicities included hypertension (22%) and fatigue (12%). CONCLUSIONS: BCNU/Bev is a safe and tolerable treatment for rGBM. Patients with MGMT+/IDH+ derive the greatest benefit from the treatment combination in the second-line setting. Nonetheless, high YKL40 expression discourages the use of antiangiogenic therapy.

Efficiency signal conversion parameter to evaluate astigmatic femtosecond-optical parametric oscillator cavities.

In this work, we define the efficiency signal conversion numerical parameter, Veff, useful to evaluate the operation efficiency of femtosecond-Optical Parametric Oscillator (fs-OPO) cavities considering the astigmatism effect. For the validation of the Veff, we have performed experimental measurements. We present different high efficiency home-made singly resonant fs-OPO cavities, with signal tuneability from 1.1 µm to 1.6 µm based on a 0.5 mm Periodically Poled Lithium Niobate doped with MgO (MgO:PPLN) crystal. We have also defined the pump energy threshold per crystal unit length, ζp,th. Pump threshold, achieved by following the Veff, was 142 mW at 810 nm, and ζp,th = 2.10 nJ/mm, the lowest value, in comparison with other studies. The Veff is based on an ABCD matrix Gaussian beam propagation method, which calculates the mode coupling between the pump and signal beams along the crystal under different cavity configurations taking into account the astigmatism. The model was compared and tested with 3 different experimental singly resonant fs-OPO ring cavity configurations that we have defined as single-folded, two-folded, and direct-pump cavity.

Utilidad clínica del Antígeno Carcinoembrionario (ACE), Tomografía convencional (TC) y PET-CT en el diagnóstico de adenocarcinoma colorrectal recidivante / Clinical utility of Carcinoembryonic Antigen (ACE), conventional tomography (CT) and PET-CT in the diagnosis of recurrent colorectal adenocarcinoma

Introduction: Colorectal cancer is one of the most prevalent tumors in the world. In the surveillance setting of recurrent colorectal cancer, laboratory test like carncinoembryonic antigen (CEA) and imaging tests like computed tomography (CT) and positron emission tomography (PET/CT) are available. We performed this study to establish the predictive accuracy of these tests to an early identification of recurrent colorectal cáncer. Materials and Methods: Thirty six patients at stages I , III and IV, after single metastasis resection of colorectal cáncer were identified. We assessed the utility of CEA, CT and PET-CT in the follow-up of these patients to improve the diagnosis of recurrent disease. Results: Of 36 studied patients, 27 /75%) had recurrence; the median age was 61 year-old and the median lap-time 16 months. The PET PET/CT scan obtained the following results: sensitivity 96.7%, specificity 88.9%, positive predictive value 96.3%, negative predictive value 88.9%, positive likekihood ratio 8.7 and negative likelihood ratio 0.04. Discusion: The best tool to make diagnosis of colorectal cancer and its recurrence is PET­CT, however, none of these tests could make the diagnosis by themselves. It has to be confirmed by histopathologic studies plus other exams.

Identifying and Analyzing the Diversity of Resistance Gene Analogs in Colombian Rubus Genotypes.

Five Andean blackberry Rubus genotypes, three resistant and two susceptible to anthracnose, were used to identify regions in the Rubus genome with homology to disease-resistance genes found in other plant species. Polymerase chain reaction amplification with 12 pairs of primers and fragment cloning yielded 520 clones, of which 151 showed inserts between 500 and 700 bp long. When sequenced, 47 clones showed homology with two types of resistance genes, non-Toll/interleukin-1 receptor (TIR) nucleotide binding site (NBS) leucine-rich repeat (LRR) and TIR-NBS-LRR, thereby confirming their designation as resistance gene analogs (RGAs). The number of RGAs detected per Rubus genotype ranged from 7 to 11, with the highest in a wild resistant and a cultivated susceptible genotype. Rubus RGAs were also homologous with several non-TIR- and TIR-type RGAs found in other members of the Rosaceae family (Rosa hybrid cultivar, Rosa roxburghii, Malus × domestica, M. prunifolia, M. baccata, M. floribunda, Pyrus communis, Prunus persica, P. kansuensis, P. avium, and Fragaria vesca). Three RGAs shared identity with two Rosaceae RGAs associated with the CRPM1 locus for powdery mildew resistance in R. roxburghii and the Rosa hybrid cultivar. This is the first report on RGAs present in the Andean blackberry in Colombia.

Performance assessment of the single photon emission microscope: high spatial resolution SPECT imaging of small animal organs.

The single photon emission microscope (SPEM) is an instrument developed to obtain high spatial resolution single photon emission computed tomography (SPECT) images of small structures inside the mouse brain. SPEM consists of two independent imaging devices, which combine a multipinhole collimator, a high-resolution, thallium-doped cesium iodide [CsI(Tl)] columnar scintillator, a demagnifying/intensifier tube, and an electron-multiplying charge-coupling device (CCD). Collimators have 300- and 450-µm diameter pinholes on tungsten slabs, in hexagonal arrays of 19 and 7 holes. Projection data are acquired in a photon-counting strategy, where CCD frames are stored at 50 frames per second, with a radius of rotation of 35 mm and magnification factor of one. The image reconstruction software tool is based on the maximum likelihood algorithm. Our aim was to evaluate the spatial resolution and sensitivity attainable with the seven-pinhole imaging device, together with the linearity for quantification on the tomographic images, and to test the instrument in obtaining tomographic images of different mouse organs. A spatial resolution better than 500 µm and a sensitivity of 21.6 counts·s-1·MBq-1 were reached, as well as a correlation coefficient between activity and intensity better than 0.99, when imaging 99mTc sources. Images of the thyroid, heart, lungs, and bones of mice were registered using 99mTc-labeled radiopharmaceuticals in times appropriate for routine preclinical experimentation of <1 h per projection data set. Detailed experimental protocols and images of the aforementioned organs are shown. We plan to extend the instrument's field of view to fix larger animals and to combine data from both detectors to reduce the acquisition time or applied activity.

Performance assessment of the single photon emission microscope: high spatial resolution SPECT imaging of small animal organs

The single photon emission microscope (SPEM) is an instrument developed to obtain high spatial resolution single photon emission computed tomography (SPECT) images of small structures inside the mouse brain. SPEM consists of two independent imaging devices, which combine a multipinhole collimator, a high-resolution, thallium-doped cesium iodide [CsI(Tl)] columnar scintillator, a demagnifying/intensifier tube, and an electron-multiplying charge-coupling device (CCD). Collimators have 300- and 450-µm diameter pinholes on tungsten slabs, in hexagonal arrays of 19 and 7 holes. Projection data are acquired in a photon-counting strategy, where CCD frames are stored at 50 frames per second, with a radius of rotation of 35 mm and magnification factor of one. The image reconstruction software tool is based on the maximum likelihood algorithm. Our aim was to evaluate the spatial resolution and sensitivity attainable with the seven-pinhole imaging device, together with the linearity for quantification on the tomographic images, and to test the instrument in obtaining tomographic images of different mouse organs. A spatial resolution better than 500 µm and a sensitivity of 21.6 counts·s-1·MBq-1 were reached, as well as a correlation coefficient between activity and intensity better than 0.99, when imaging 99mTc sources. Images of the thyroid, heart, lungs, and bones of mice were registered using 99mTc-labeled radiopharmaceuticals in times appropriate for routine preclinical experimentation of <1 h per projection data set. Detailed experimental protocols and images of the aforementioned organs are shown. We plan to extend the instrument's field of view to fix larger animals and to combine data from both detectors to reduce the acquisition time or applied activity.

Effects of primary spherical aberration, coma, astigmatism and field curvature on the focusing of ultrashort pulses: homogenous illumination.

We analyze the spatiotemporal intensity of pulses with durations of 20 fs and shorter and a carrier wavelength of 810 nm at the paraxial focal plane of an achromatic doublet lens. The incident pulse is well-collimated, and we use the Seidel aberration theory for thin lenses to evaluate the phase change due to the aberrations of the lens. In a set of cemented thin lenses with the stop at the lens, there is only spherical aberration, coma, astigmatism and field curvature, whereas the distortion aberration in the phase front is zero. We analyze the effect of these aberrations in the focusing of ultrashort pulses for homogenous illumination. We will show that the temporal spreading introduced by these aberrations in pulses shorter than 20 fs at 810 nm is very small but the spatial spreading is not, which reduces the intensity of the pulse considerably.

Effects of primary spherical aberration, coma, astigmatism, and field curvature on the focusing of ultrashort pulses: Gaussian illumination and experiment.

We analyze the spatiotemporal intensity of Gaussian temporal envelope pulses with initial durations of 200 fs and a carrier wavelength of 810 nm at the paraxial focal plane of an achromatic doublet lens for a well-collimated incoming pulse beam by using the Seidel aberration theory for thin lenses with the stop at the lens. We analyze the effect of these aberrations in the focusing of ultrashort pulses for Gaussian illumination and present experimental results for 200 fs pulses focused by a near-IR achromatic doublet.

Recommendations for use of marginal donors in heart transplantation: Brazilian Association of Organs Transplantation guideline.

The high prevalence of heart failure has increased the candidate list for heart transplantation; however, there is a shortage of viable donated organs, which is responsible for the high mortality of patients awaiting a transplantation. Because the marginal donor presents additional risk factors, it is not considered to be an ideal donor. The use of a marginal donor is only justified in situations when the risk of patient death due to heart disease is greater than that offered by the donor. These recommendations sought to expand the supply of donors, consequently increasing the transplant rate. We selected articles based on robust evidence to provide a substratum to develop recommendations for donors who exceed the traditional acceptance criteria. Recipient survival in the immediate postoperative period is intimately linked to allograft quality. Primary allograft failure is responsible for 38% to 40% of immediate deaths after heart transplantation: therefore; marginal donor selection must be more rigorous to not increase the surgical risk. The main donor risk factors with the respective evidence levels are: cancer in the donor (B), female donor (B), donor death due to hemorrhagic stroke (B), donor age above 50 years (relative risk [RR] = 1.5) (B), weight mismatch between donor and recipient < 0.8 (RR = 1.3) (B), ischemia > 240 minutes (RR = 1.2) (B), left ventricular dysfunction with ejection fraction below 45% (B), and use of high doses of vasoactive drugs (dopamine > 15 mg/kg·min) (B). Factors that impact recipient mortality are: age over 50 years (RR = 1.5); allograft harvest at a distance; adult recipient weighing more than 20% of the donor; high doses of vasoactive drugs (dopamine greater than 15 mg/kg·min) and ischemic time >4 hours. The use of a marginal donor is only justified when it is able to increase life expectancy compared with clinical treatment, albeit the outcomes are interior to those using an ideal donor.

A clinical gamma camera-based pinhole collimated system for high resolution small animal SPECT imaging

The main objective of the present study was to upgrade a clinical gamma camera to obtain high resolution tomographic images of small animal organs. The system is based on a clinical gamma camera to which we have adapted a special-purpose pinhole collimator and a device for positioning and rotating the target based on a computer-controlled step motor. We developed a software tool to reconstruct the target’s three-dimensional distribution of emission from a set of planar projections, based on the maximum likelihood algorithm. We present details on the hardware and software implementation. We imaged phantoms and heart and kidneys of rats. When using pinhole collimators, the spatial resolution and sensitivity of the imaging system depend on parameters such as the detector-to-collimator and detector-to-target distances and pinhole diameter. In this study, we reached an object voxel size of 0.6 mm and spatial resolution better than 2.4 and 1.7 mm full width at half maximum when 1.5- and 1.0-mm diameter pinholes were used, respectively. Appropriate sensitivity to study the target of interest was attained in both cases. Additionally, we show that as few as 12 projections are sufficient to attain good quality reconstructions, a result that implies a significant reduction of acquisition time and opens the possibility for radiotracer dynamic studies. In conclusion, a high resolution single photon emission computed tomography (SPECT) system was developed using a commercial clinical gamma camera, allowing the acquisition of detailed volumetric images of small animal organs. This type of system has important implications for research areas such as Cardiology, Neurology or Oncology.