Particle motion measurements near a rocky shore off Cabo Frio Island.

This paper describes the lessons learned from the experiment BIOCOM'19 carried out in January 2019, in a shallow water bay off the island of Cabo Frio (RJ, Brazil). A dual accelerometer vector sensor hydrophone was deployed for two days, near a rocky shore covered with a significant benthic fauna. The results show that the frequency band above approximately 1.5 kHz is mostly associated with invertebrate biological noise and that the acoustic and the particle motion fields have a similar behavior, following the usual dawn-dusk activity pattern, and a coherent directivity content. At low frequencies, below ∼300 Hz, the acoustic pressure and the particle acceleration fields have significantly different spectral content along time. Many of these differences are due to anthropogenic noise sources related with nearby boating activity, while during quiet periods, they may be attributed to the biological activity from the rocky shore.

Automated grading of left ventricular segmental wall motion by an artificial neural network using color kinesis images.

The present study describes an auxiliary tool in the diagnosis of left ventricular (LV) segmental wall motion (WM) abnormalities based on color-coded echocardiographic WM images. An artificial neural network (ANN) was developed and validated for grading LV segmental WM using data from color kinesis (CK) images, a technique developed to display the timing and magnitude of global and regional WM in real time. We evaluated 21 normal subjects and 20 patients with LVWM abnormalities revealed by two-dimensional echocardiography. CK images were obtained in two sets of viewing planes. A method was developed to analyze CK images, providing quantitation of fractional area change in each of the 16 LV segments. Two experienced observers analyzed LVWM from two-dimensional images and scored them as: 1) normal, 2) mild hypokinesia, 3) moderate hypokinesia, 4) severe hypokinesia, 5) akinesia, and 6) dyskinesia. Based on expert analysis of 10 normal subjects and 10 patients, we trained a multilayer perceptron ANN using a back-propagation algorithm to provide automated grading of LVWM, and this ANN was then tested in the remaining subjects. Excellent concordance between expert and ANN analysis was shown by ROC curve analysis, with measured area under the curve of 0.975. An excellent correlation was also obtained for global LV segmental WM index by expert and ANN analysis (R2 = 0.99). In conclusion, ANN showed high accuracy for automated semi-quantitative grading of WM based on CK images. This technique can be an important aid, improving diagnostic accuracy and reducing inter-observer variability in scoring segmental LVWM.

Effect of different anesthetic agents on left ventricular systolic function assessed by echocardiography in hamsters.

Determination of left ventricular ejection fraction (LVEF) using in vivo imaging is the cardiac functional parameter most frequently employed in preclinical research. However, there is considerable conflict regarding the effects of anesthetic agents on LVEF. This study aimed at assessing the effects of various anesthetic agents on LVEF in hamsters using transthoracic echocardiography. Twelve female hamsters were submitted to echocardiography imaging separated by 1-week intervals under the following conditions: 1) conscious animals, 2) animals anesthetized with isoflurane (inhaled ISO, 3 L/min), 3) animals anesthetized with thiopental (TP, 50 mg/kg, intraperitoneal), and 4) animals anesthetized with 100 mg/kg ketamine plus 10 mg/kg xylazine injected intramuscularly (K/X). LVEF obtained under the effect of anesthetics (ISO=62.2±3.1%, TP=66.2±2.7% and K/X=75.8±1.6%) was significantly lower than that obtained in conscious animals (87.5±1.7%, P<0.0001). The K/X combination elicited significantly higher LVEF values compared to ISO (P<0.001) and TP (P<0.05). K/X was associated with a lower dispersion of individual LVEF values compared to the other anesthetics. Under K/X, the left ventricular end diastolic diameter (LVdD) was increased (0.60±0.01 cm) compared to conscious animals (0.41±0.02 cm), ISO (0.51±0.02 cm), and TP (0.55±0.01 cm), P<0.0001. The heart rate observed with K/X was significantly lower than in the remaining conditions. These results indicate that the K/X combination may be the best anesthetic option for the in vivo assessment of cardiac systolic function in hamsters, being associated with a lower LVEF reduction compared to the other agents and showing values closer to those of conscious animals with a lower dispersion of results.

Relation of regional sympathetic denervation and myocardial perfusion disturbance to wall motion impairment in Chagas' cardiomyopathy.

Impairment of sinus node autonomic control and myocardial perfusion disturbances have been described in patients with chronic Chagas' cardiomyopathy. However, it is not clear how these conditions contribute to myocardial damage. In this investigation, iodine-123 (I-123) meta-iodobenzylguanidine (MIBG) and thallium-201 myocardium segmental uptake were studied in correlation with the severity of left ventricular (LV) dysfunction detected in various phases of Chagas' heart disease. Group I consisted of 12 subjects (43 +/- 4 years, 7 men) with no symptoms and no cardiac involvement on electrocardiogram (ECG) or echocardiography; group II consisted of 13 patients (48 +/- 3 years, 9 men) with abnormal resting ECG and/or echocardiographic segmental abnormalities, and LV ejection fraction of > or = 0.5; group III was comprised of 12 patients (59 +/- 3 years, 10 men) with more severe heart disease, LV dilation, and LV ejection fraction of < 0.5. Eighteen control volunteers (38 +/- 3 years, 9 men) were also included in the study. I-123 MIBG single-photon emission computed tomographic (SPECT) segmental uptake defects were observed in group I (33%), group II (77%), and group III (92%). Quantitative analysis showed mean areas of reduced LV I-123-MIBG uptake: group I was 3.7 +/- 2.1%; group II was 8.3 +/- 2.3%; and group III was 19.0 +/- 3.3%. The differences between group I and both groups II and III were statistically significant (p < 0.001, analysis of variance test). Myocardial perfusion defects (reversible, fixed, and paradox) were observed in group I (83%), group II (69%), and group III (83%). A marked topographic association between perfusion, innervation, and wall motion abnormalities (assessed by gated-SPECT perfusion studies) was observed in all the groups. Defects predominated in the inferior, posterior lateral, and apical LV regions. Thus, extensive impairment of cardiac sympathetic function at the ventricular level occured early in the course of Chagas' cardiomyopathy and was related to regional myocardial perfusion disturbances, before wall motion abnormalities. Both conditions are associated with progression of ventricular dysfunction.

Acute myocardial infarction complicating the clinical course of dilated cardiomyopathy in childhood.

An acute myocardial infarction occurred in a 6-year-old child with dilated cardiomyopathy. This caused severe hemodynamic deterioration that led to a fatal outcome. Autopsy revealed diffuse myocardial atrophy without cell infiltrate, normal epicardial coronary arteries, and a massive healed anteroapical infarction. Coronary embolism or spasm could not be ruled out as the cause of the infarction.

Gene polymorphisms in the TNF locus and the risk of myocardial infarction.

We investigated two genetic polymorphisms in the tumor necrosis factor locus (TNF-alpha -308 G-->A and LT-alpha +252 A-->G) as risk factors for coronary atherothrombotic disease (CAD) by determining its prevalence in 148 survivors of myocardial infarction (MI) with angiographically-proven severe CAD, and in 148 age-, gender- and race-matched controls. The odds ratio (OR) for MI related to the mutant TNF-alpha and LT-alpha alleles was 0.8 (CI95: 0.4-1.3) and 1. 3 (CI95: 0.8-2.0), respectively. We also sought interaction of smoking and metabolic risk factors for MI with each mutant genotype. Smokers not carrying the LT-alpha +252 A-->G mutation had a risk of MI of 2.7 (CI95: 1.4-5.4) whereas in smoking carriers the risk was 6. 9 (CI95: 3.4-14.1). An interactive effect of the LT-alpha mutation may also exist with dyslipidemia (OR for MI in non-carriers was 12 [CI95: 3.2-41.3] and in carriers the OR was 39, [CI95: 5.1-301] and with obesity (OR for MI was 2.7, [CI95: 1-7.2] in non-carriers and in carriers the OR was 6 [CI95: 2.1-16.8]). Lastly, the OR for MI in obese non-carriers of TNF-alpha -308 G-->A was 2.8 (CI95: 1.3-6) and in obese carriers the OR was 14.5 (CI95: 1.8-113). Although significant interactive effects could not be detected, the findings suggest that interaction of polymorphisms in the TNF locus with major risk factors for CAD may exist, and should be explored in larger studies.

Severe myocarditis and esophagitis during reversible long standing Chagas' disease recrudescence in immunocompromised host.

An unusual form of reagudization of Chagas' disease, from its indeterminate phase, was documented in an immunocompromised patient. Long-standing progressive visceral aggression due to extensive intracellular proliferation of T. cruzi manifested by severe isolated right ventricular failure and esophageal ulcerations. Antiparasite chemotherapy was effective in the control of the disease.

Acquired aorto-coronary vein fistula after bypass graft surgery: report of two cases with long-term follow-up.

Two patients who underwent bypass surgery with saphenous grafts had a fistula resulting from inadvertent grafting of the cardiac vein correspondent to a targeted diagonal artery. Hemodynamic effects at rest were restricted to moderate elevation of the pulmonary blood flow, by 23 and 13% respectively, at 5 and 12 months postoperatively. No objective signs of ischemia could be elicited in either patient, in the fistula related region, and left ventricular function remained within normal limits in both cases throughout the follow-up period (36 and 24 months, respectively).

Reversible segmental left-ventricular dysfunction caused by accidental administration of sympathomimetic drug in human.

A inadvertently administrated high dose of sympathomimetic drug induced cardiogenic shock manifestations in a previously healthy woman. This state was characterized by EKG subendocardial injury, serum cardiac enzymes elevation, extensive regional left ventricular wall motion abnormalities on echocardiogram. Therapeutics included oxygen, systemic vasodilators and diuretics. Clinical recovery occurred over a four days period and parallels the normalization of echocardiogram and EKG alterations.

Cardiac autonomic impairment and early myocardial damage involving the right ventricle are independent phenomena in Chagas' disease.

Cardiac autonomic impairment and right side heart failure are prominent features in patients with Chagas' disease, but no causal relationship between these phenomena has been disclosed and the pathophysiology of such manifestations is unclear. Aim of study was to assess the cardiac autonomic control and biventricular function in chagasic patients in early stages of the disease, using radionuclide angiography, Valsalva manoeuvre, head-up tilt and baroreflex sensitivity evaluation. Thirty-one chagasic patients with no clinical signs of Chagas' heart disease-16 in the indeterminate phase and 15 with sole organic digestive involvement-were studied, and results compared with those obtained in 14 normal volunteers. No significant differences were observed among the three groups, in regard to any systolic or diastolic parameter of LV function, including ejection fraction, peak ejection and filling rates and correspondent times, time to end-systole, and the standard deviation of phase values. The indeterminate and digestive groups of chagasics had significantly lower right ventricular ejection fraction (45.7 +/- 6.3 and 46.2 +/- 10.1 respectively) and peak ejection rate (respectively 2.8 +/- 0.6 and 2.9 +/- 0.6) and higher right ventricular phase standard deviation (22.4 +/- 5.9 and 20.1 +/- 5.6 degrees, respectively), as compared with the control group (53.6 +/- 4.3, 3.5 +/- 0.5, and 15.8 +/- 3.8 respectively for right ventricular ejection fraction, peak ejection rate and phase standard deviation). No significant differences were found between the results of autonomic evaluation in the control and indeterminate groups of chagasic patients. The group of digestive disease patients showed abnormally lower Valsalva ratio (1.5 +/- 0.15), baroreflex sensitivity (8.85 +/- 2.05 ms/mmHg) and parasympathetically-dependent heart rate response to tilt (8.85 +/- 8.42 beats/mm) and higher Valsalva delay (15.67 +/- 1.35 s) values, compared with the control group (respectively 1.85 +/- 0.49, 20.23 +/- 12.66 ms/mmHg, 21.61 +/- 5.77 beats/mm and 10.1 +/- 2.5 s). Thus, cardiac autonomic impairment is a prominent feature in chagasic patients with the digestive but not the indeterminate form of Chagas' disease. It bears no causative relationship to the early myocardial damage that is apparent only regarding right ventricular function, in both groups of patients. Early right ventricular dysfunction is a likely mechanism for the marked predominance of systemic over pulmonary congestion when heart failure supervenes in patients with Chagas' disease.

HFE gene mutations in coronary atherothrombotic disease.

Although iron can catalyze the production of free radicals involved in LDL lipid peroxidation, the contribution of iron overload to atherosclerosis remains controversial. The description of two mutations in the HFE gene (Cys282Tyr and His63Asp) related to hereditary hemochromatosis provides an opportunity to address the question of the association between iron overload and atherosclerosis. We investigated the prevalence of HFE mutations in 160 survivors of myocardial infarction with angiographically demonstrated severe coronary atherosclerotic disease, and in 160 age-, gender- and race-matched healthy control subjects. PCR amplification of genomic DNA followed by RsaI and BclI restriction enzyme digestion was used to determine the genotypes. The frequency of the mutant Cys282Tyr allele was identical among patients and controls (0.022; carrier frequency, 4.4%), whereas the mutant His63Asp allele had a frequency of 0.143 (carrier frequency, 27.5%) in controls and of 0.134 (carrier frequency, 24.5%) in patients. Compound heterozygotes were found in 2 of 160 (1.2%) controls and in 1 of 160 (0.6%) patients. The finding of a similar prevalence of Cys282Tyr and His63Asp mutations in the HFE gene among controls and patients with coronary atherothrombotic disease, indirectly questions the possibility of an association between hereditary hemochromatosis and atherosclerosis.

Studies of the coronary circulation in Chagas' heart disease.

Pathogenesis of chronic Chagas' heart disease may include various disturbances in the coronary circulation, that could be responsible for the myocardial lesions seen in human hearts and in experimental models of the disease. In this paper we critically reviewed the anatomical and functional abnormalities described in chronic chagasic patients, pertaining to the so-called vascular pathogenetic theory of Chagas' disease. The epicardial coronary arteries are usually free of significant obstructive disease in nonselected groups of chagasic patients examined at autopsy or by coronary angiography. However, chagasic patients who were studied after an episode of acute myocardial infarction, show the same patterns of atherosclerotic coronary artery disease seen in the general nonchagasic population. Studies of chagasic patients with angiographically normal coronary arteries, by several scintigraphy methods, revealed myocardial perfusion abnormalities which may be caused by the microcirculatory derangements described in animals experimentally infected with the T. cruzi. Since hypoperfusion has been detected in regions with normal or mildly impaired wall motion, it is likely that the microvascular disturbances precede and may be causative mechanism for the subsequent myocardial damage. We speculate that hibernating ventricular areas may occur in chagasic patients, on the basis of the evidence gathered from these studies. Recent investigations of chronic patients with Chagas' disease and chest pain showed attenuation of the vasomotor responses to physiological and pharmacological stimuli, in the epicardial coronary arteries.

[Congenital left sinus of Valsalva aneurysm]. / Aneurisma congênito do seio de Valsalva esquerdo.

Two cases of left sinus of Valsalva congenital aneurysm (SVCA), incidentally found are described. The authors call attention on rarity of them, and present new concepts about their morphogenesis and incidence. They also suggested a higher incidence of asymptomatic and undiagnosed cases of SVCA should be considered.

[Esophageal origin of precordial pain in chagasic patients with normal subepicardial coronary arteries]. / Origem esofágica de dor precordial em pacientes chagásicos com artérias coronárias subepicárdicas normais.

PURPOSE: To study the chest pain of esophageal origin in chagasic patients (CH) and non-chagasic subjects (NCH) with normal coronary arteries. METHODS: The study comprised 48 patients: 33 CH (age 56 years, 50% male) and 15 NCH (age 47 years, 25 male), with precordial chest pain and normal subepicardial coronary arteries. They were assigned to upper digestive tract radiologic and endoscopic study, esophageal manometric evaluation at baseline and after provocative tests (Bernstein and intravenous edrophonium). RESULTS: Radiologic study: 14 (42%) CH and 4 (27%) NCH had esophageal dilation (p > 0.05). Hiatal hernia was documented in 7 (21%) CH and 6 (40%) NCH (p > 0.05). 2) Digestive endoscopy: In 15 (45%) CH and 6 (40%) NCH distal esophagitis were seen. In the NCH, esophagitis occurred with hiatal hernia; however only 30% of CH with esophagitis had also hiatal hernia while another 30% had esophageal dilation. 3) Esophageal motility disorders (EMD): 11 (33%) CH showed EMD: 8 with inferior esophageal sphincter achalasia (IESA) and 3 with diffuse esophageal spasm. Among NCH, 2 (13%) had IESA (p > 0.05). 4) Bernstein test--a positive test was seen in 5 (15%) CH and 3 (20%) NCH-p > 0.05. CH with esophageal dilation had 14% of positive results, while CH without esophageal dilation had 16%-p > 0.05. 5) Intravenous edrophonium-esophageal contraction amplitude enhancement provoked by the drug infusion was clearly attenuated in the chagasic (6.9 +/- 12.7 mmHg) when compared with the NCH group (18.8 +/- 21.4 mmHg). A positive test (i.e. chest pain) was obtained in only one patient who was NCH. CONCLUSION: Esophageal pain could be elicited at a relatively low and comparable rate in both groups of patients.

[Clinical profile, coronary angiography findings and early outcome in young patients with acute myocardial infarction in the thrombolytic era]. / Perfil clínico, cinecoronariográfico e evolutivo precoce de pacientes jovens com infarto agudo do miocárdio na era trombolítica.

PURPOSE: To assess the clinical, angiographic and early follow-up findings of young patients suffering an acute myocardial infarction, in comparison with older patients with infarction, in the thrombolytic era. METHODS: A retrospective analysis of the medical records of 46 patients < 40 years-old (group I) at the time of an acute myocardial infarction was compared with that of 46 older patients, randomly selected, presenting with this syndrome between february, 1991 and february, 1996 (group II). In both groups a comparison was conducted regarding the proportions of gender, risk factors, type of infarction (Q vs non-Q), left ventricular function, coronary anatomy and early mortality (1 month). The medical treatment was comparable for both groups, including the utilization of thrombolytics. RESULTS: The groups were discriminated only by: higher prevalence of smoking, of angiographically normal coronary arteries, and of non-critical (< 75% reduction of luminal diameter) coronary stenosis in group I; in the older group a higher proportion of patients had multivessel disease. Although not reaching statistical significance, a trend was observed to a more benign early course of the infarction in the patients less than < 40 years-old. CONCLUSION: The present findings are similar to those described in the pre-thrombolytic era, for young patients suffering an acute myocardial infarction.

[Reagudization of Chagas myocarditis inducing exclusive right ventricular failure]. / Reagudização de cardite chagásica provocando insuficiência ventricular direita exclusiva.

Woman, 42 years-old, receiving immunosuppressive therapy for a lymphoma, presented reagudization of Chagas' disease, from its indeterminate phase. Intense inflammatory visceral aggression, due to extensive intracellular proliferation of the Trypanosoma cruzi, was the likely mechanism for acute myocarditis leading to severe right ventricular failure. Antiparasite chemotherapy was effective in the control of visceral involvement and for the remission of cardiac failure. The clinical course in this case is compatible with the hypothesis of early right ventricular damage in Chagas' disease.

[Detection of myocardial ischemia in chronic Chagas disease patients with atypic precordial pain by exercise and Holter tests]. / Detecção de isquemia miocárdica em chagásicos crônicos com precordialgia atípica pelos testes de esforço e Holter.

PURPOSE: To determine the incidence and characteristics of myocardial ischemia, as detected by stress electrocardiography and Holter monitoring in Chagas' patients whose main complaint was precordial pain. METHODS: Thirty-one consecutive patients with Chagas' disease diagnosed on the basis of clinical and serological tests, and precordial pain severe enough to warrant cardiac catheterization were studied. Mean age was 54.4 +/- 9.6 years, and 51% were males. EKG changes indicative of myocardial ischemia were sought during maximal exercise and also during 24-hour Holter monitoring. The detection of myocardial ischemia by each one of these tests was compared by Fischer exact test, and also correlated to anatomical and functional results of coronary angiography at rest and after standardized hyperventilation for detecting coronary vasospasm. RESULTS: Baseline EKG changes mainly associated with ventricular conduction defects precluded the analysis of the ST segment in 11 patients. Among the other 20 patients, 7(35%) had angina during the exercise test, of whom only 2(10%) showed concomitant ischemic ST changes: one had 90% stenosis in the circumflex branch and the other 50% reduction of luminal diameter in a intramyocardial segment of the left anterior descending coronary artery, undergoing further 30% constriction after hyperventilation, with pain and ST-elevation that responded to nitrate administration. Thus, a positive correlation between a positive EKG exercise test with accompanying symptoms, and organic/functional coronary artery disease was found (p = 0.03). Holter tracings of good quality were obtained in 16 patients. Angina-like symptoms occurred in 25% of these patients, without concomitant ischemic or dysrhythmic EKG changes. Conversely, silent ischemia was detected in 1 (5%) patient during exercise and in 3 (18%) patients during the Holter monitoring. None of these patients had any evidence of organic or functional alterations in the coronary arteries. The absence of significant (> 50%) narrowing of the coronary arteries, at baseline and after hyperventilation, was also documented in the 11 patients in whom no valid EKG tracings were obtained for analysis. CONCLUSION: EKG-based methods for detecting myocardial ischemia are of limited value in the general population with Chagas' disease presenting with precordial pain, due to the high prevalence of baseline ST changes. The overall incidence of significant coronary artery disease, as detected by angiography, was low but not negligible in this population of Chagas' patients with precordial pain (4%). Nevertheless, a positive EKG test based on ST changes and accompanying pain has a 100% positive predictive accuracy for the presence of organic or functional coronary abnormalities. No additional yield was obtained with Holter monitoring, for the elucidation of the pathophysiology of the precordial pain in Chagas' patients with atypical angina. The significance of episodes of silent ischemia in some of these patients, with angiographically normal coronary arteries, remains to be determined.

[Risk stratification in acute myocardial infarction survivors. Exercise stress test versus coronary angiography]. / Estratificação prognóstica em sobreviventes ao infarto agudo do miocárdio. Teste ergométrico versus cinecoronariografia.

PURPOSE: To compare the predictive accuracy for future ischemic events of heart rate limited treadmill exercise test (HET) and coronary angiography (CA) applied to survivors of an uncomplicated myocardial infarction. METHODS: 142 consecutive patients (55 +/- 11 years, 80% males), presenting a non complicated acute myocardial infarction (AMI) were included. HET was performed 10 +/- 3 days after AMI, and CA during hospital stay or within 4-6 weeks. HET positivity criteria were: 1) horizontal or down-sloping ST segment displacement > or = 1 mm; 2) angina; 3) arterial pressure drop during exercise; 4) low workload (< 6 METS); 5) complex ventricular arrhythmia. At CA lesions causing > or = 50% of luminal reduction were considered significant. HET and CA results were correlated to ischemic events occurring during the follow-up (unstable angina in 20%, cardiac death 6%, and reinfarction 6%). RESULTS: HET was positive in 69 (49%) patients, exhibiting a positive predictive value for ischemic events (PV+) of 26% and a negative predictive value (PV-) of 77%. The mean event-free time was 43 +/- 3 months for positive HET and 46 +/- 3 months for a negative one (p = 0.48). CA showed 0-1 vessel involvement in 93 (66%) patients and > or = 2 vessels in 49 (34%) patients. The presence of multivascular disease at CA presented a PV+ of 37% and PV- of 82%; the mean event-free time was 37 +/- 4 months for patients with multivascular involvement and 48 +/- 2 months for patients without this pattern (p = 0.007). CONCLUSION: The predictive accuracy of HET for future ischemic events in the thrombolytic era is markedly reduced. This population of AMI survivors presents an overall good prognosis that seems to justify the poor predictive accuracy of this test.

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.