Biomedical subjects

M F Botelho

Publications and source records attributed to M F Botelho.

7 recordsLinked to original sources

PubMed2002

Lymphatic uptake of pulmonary delivered radiolabelled solid lipid nanoparticles.

UNLABELLED: Lymphatic drainage plays an important role in the uptake of particulates in the respiratory system, being also associated to the spreading of lung cancer through metastasis development. In recent years solid lipid nanoparticles (SLN) have been proposed as carriers of anti-tumoural drugs, for their low toxicity and surface characteristics make them suitable for either imaging (gamma-scintigraphy) or therapy upon encapsulation of cytotoxic drugs. Assessment of inhaled radiolabelled SLN biodistribution is described in the present work. METHODS: Nanoparticles (200 nm) were radiolabelled with 99mTc using the lipophilic chelator D,L-hexamehylpropyleneamine oxime (HMPAO). Biodistribution studies were carried out following aerosolisation and administration of a 99mTc-HMPAO-SLN suspension to a group of adult male Wistar rats. A 60 min dynamic image acquisition was performed in a gamma-camera, followed by static image collection at 30 min intervals up to 4 h postinhalation. Radiation counting was performed in organ samples, collected after the animals were sacrificed. RESULTS: The data show an important and significant uptake of the radiolabelled SLN into the lymphatics after inhalation, and a high rate of distribution in periaortic, axillar and inguinal lymph nodes. CONCLUSION: Results indicate that SLN could be effective colloidal carriers for lymphoscintigraphy or therapy upon pulmonary delivery.

Administration, Inhalation↗

PubMed2001

First pass evaluation of blood velocity in the pulmonary artery.

Studying the kinetics of blood flow in the pulmonary artery using non-invasive techniques may be an important tool in assessing the prognosis of lung diseases. The aim of this study was to ascertain dynamic parameters of pulmonary blood flow, particularly the velocity of a small bolus of a radioactive tracer after intravenous injection. Since the shape and distribution pattern of the bolus changes substantially from frame to frame, common image processing techniques for motion detection or other techniques, such as accumulation of subtracted images, segmentation and spectral analysis with temporal/spatial filtering, are unable to properly evaluate the motion of the bolus. However, the passage of the bolus from the arm to the lungs was visualized with good contrast through acquisition of a first pass sequence of scintigraphic images. The wave form of the bolus becomes increasingly complex as it progresses towards the pulmonary artery. In the proposed method the time-activity curves for each pixel are displayed. It is assumed that the peaks of the maximum counts in these curves correlate with the time after injection that the bolus takes to cross each pixel (bolus head). The bolus head contains information on time, space and activity, and allows the velocity of the studied fluid to be calculated. We demonstrated a mean velocity through the pulmonary artery trunk in resting patients of approximately 11 cm/s, with a mean residence time of 0.5 s.

Algorithms↗

PubMed1998

Cardiac lymphatic dynamics after ischemia and reperfusion--experimental model.

ABSTRACT. The aim of the present study was to investigate the lymphatic cardiac circulation in an experimental model of ischemia plus reperfusion in mongrel dogs (Canis familiaris L). As radiotracer we used 0.2-0.25 ml (111 MBq) of 99mTc-Re2S7 colloid (+/-10 microm), injected subcapsullary below the second diagonal of the descending anterior ligated coronary artery with a special needle. A gamma-camera/Starport + DecStation were used for data acquisition. Four experimental groups with five animals each were established: G I = controls; G II = immediately after acute myocardial infarction (AMI); G III = late infarction (5 days after AMI); G IV = ischemia (90 min) + reperfusion. Four regions of interest (ROIs) were chosen: injection area (ZA), above (ZB), near right (ZD), and far right (ZC) from ZA. Mean disappearance times in ZA and dynamic parameters in the other ROIs were determined from activity/time curves drawn in each area, using homemade software. The results obtained seem to indicate that the methodology is appropriate to a detailed study of lymphatic drainage in pathological situations in animal models.

Animals↗

PubMed1993

Evaluation of pulmonary systemic blood flow using ECG gated acquisition.

We propose a functional parametric analysis method using ECG-gated 99mTc-labeled red blood cell (RBC) imaging for detection and characterization of periodic variations in local blood activity in the lungs during cardiac cycle. We validated in animal experiments that such count variations correlate with cyclical pulmonary blood flow and may be used for evaluation of systemic-to-pulmonary shunts. Clinical studies were performed in 48 patients. After labeling the RBC pool with 99mTc, ECG-gated gamma camera images of both lung fields were acquired and processed to obtain Fourier transforms of time/activity functions in selected regions. The first harmonic parametric images of amplitude and phase were derived. There was an excellent correlation (r = 0.92) between activity variations and pulsatile flow measured by our method with that obtained by the thermodilution method in dog experiments (n = 10) after implantation of a systemic-to-pulmonary shunt. Patient studies showed the technique to be sensitive in detecting and quantifying abnormal systemic-to-pulmonary blood flow. Lung pulsatile flow can thus be noninvasively measured from functional parametric phase and amplitude images; the technique may be useful for detecting and quantifying abnormal systemic-to-pulmonary blood flow in man.

Animals↗

PubMed1993

[Tomodensitometry and radioisotopic methods in the study of unilateral lung hyperlucencies of vascular origin].

Among the causes of the radiological entity known as unilateral or total hyperlucent lung is the decreased blood flow in the lungs. Unilateral and total hyperlucent lung results, among other factors, from the decreased intrapulmonary blood flow. Classically, the diagnosis and haemodynamic evaluation of these situations were usually made through invasive methods: right heart catheterism to perform angiopneumography and pressure evaluations as well as oximetry at several levels of the vascular network, thoracic aortography eventually associated with selective arteriography to detect the abnormalities of the systemic thoracic circulation. In this context, the authors propose for the diagnosis and study of this pathology, a new non-invasive methodology. In order to achieve this propose, we studied 8 patients, all of them performed clinical and laboratory evaluations, chest chi-ray, electrocardiographic and functional respiratory exams, as well angiopneumography, thoracic aortography tomodensitometry including qualitative (to study the lung arterial vasculature) and quantitative (to evaluate CT density of each lung in Hounsefield unit and two radioisotopic tests, including a ventilation/perfusion study with 133 chi e and HAM-99mTc, through an original software--four parameter histograms allowing simultaneous information of ventilation and perfusion at the pixel level and estimation of the V/Q; the other is the pulmonary gating through which it is possible to identify and quantify the arterio-arterial shunts.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗

PubMed1991

Ventilation and perfusion display in a single image.

A new method of ventilation and perfusion display onto a single image is presented. From the data on regions of interest of the lungs, three-dimensional histograms are created, containing as parameters X and Y for the position of the pixels, Z for the perfusion and colour for local ventilation. The perfusion value is supplied by sets of curves having Z proportional to the local perfusion count rate. Ventilation modulates colour. Four perspective views of the histogram are simultaneously displayed to allow visualization of the entire organ. Information about the normal ranges for both ventilation and perfusion is also provided in the histograms.

Adult↗

PubMed1986

Dynamic imaging of the compliant perfusion of the lungs.

A method for the study of the dynamics of the perfusion of the compliant vascular tree of the lungs using in vivo labelled 99mTc red cells and ECG gating is presented. Following blood pool labelling, posterior, ECG gated gamma camera images were acquired in time intervals of about 40 ms for 1,000-2,000 cardiac cycles. The images show the lungs plus the heart and great vessels. The image sequence containing the periodic variation of the blood activity in the lungs during the cardiac cycle is analyzed to obtain volume curves and functional images of the amplitude and phase of the lung perfusion. The interference of the heart and great vessels with the left lung can be avoided by excluding the superimposed areas in the ROIs with the sacrifice of part of the left lung. This technique allows dynamic visualization of the perfusion process in the compliant arterial and venous vascular trees of the lungs. The results obtained with this method in normals and some pathologies are discussed.

Electrocardiography↗