[Methods for the quantification of left ventricular volumes assessed by radionuclide ventriculography (first part)].

The purpose of this study was to point out the existing methods and to describe and evaluate the accuracy of new, original, "Geometric-count-based" (GCB) method, based on radionuclide ventriculography, for the measurement of left ventricular volumes compaired to the contrast ventriculography. By having done this, the aim was to compare the accuracy of GCB method and other two radionuclide methods available for left ventricular volume measurements: Count-bases Massardo method and gated blood pool SPECT method. In GCB method count based data from radionuclide ventriculography were combined with geometric ones assuming a prolate ellipsoid left ventricular's shape with identical short axes. The following equation for computing left ventricular end-diastolic volume was developed: EDV = 2 x c x M x C(tot)/C(max), (1) where: 2c--manually drown short axis of prolate ellipsoid (left ventricle) at end-diastolic frame, M-calibrated pixel size, C(tot)--total counts in left ventricular's region of interest at end-diastolic frame, C(max)--maximum pixel counts in left ventricular's region of interest. Physical experiments with two different heart shaped phantoms were used to compare volumes assessed by all three radionuclide methods with the true volumes. The true volumes of cylindrical and ellipsoid phantoms of 112.5 ml and 190.5 ml, were computed to be 114 ml and 196 ml by our GCB method, 168 ml and 180 ml by Massardo method and 142 ml and 222 ml by gated blood pool SPECT methods, respectively. In clinical study, in 65 patients volumes assessed by radionuclide methods were compared to volumes measured using single plane contrast ventriculography as a gold standard. A good correlation of our original method was obtained with a contrast ventriculography for both EDV/m2 and ESV/m2 (r = 0.94, r = 0.92), slightly lower for Massardo method (EDV/m2: r = 0.90, ESV/m2 : r = 0.89) and significantly lower for gated blood pool SPECT (EDV/m2: r = 0.85, ESV/m2: r = 0.81, p < 0.01). In conclusion, both, phantom and clinical studies indicate that GCB radionuclide method is accurate, noninvasive for left ventricular volumes' measurement and should be widely used in everyday clinical practice.

[Radionuclide ventriculography in evaluation of cardiac function in valvular diseases (second part)].

Patients with valvular heart disease usually require serial, long-term evaluation to determine changes in the severity of their disorder, its effect on ventricular function, and the advisability of corrective surgery. Echocardiography is excellent technique for visualization of the motion of atrioventricular valves, but it is not reliable method for quantifying valvular insufficiency. Equilibrium radionuclide ventriculography is readily available, noninvasive means for quantifying the degree of valvular insufficiency, using left to right ventricular stroke volume ratio. Besides, other parameters important for cardiac function, such as ventricular volumes and ejecton fraction can also be calculated. In this paper the methodology of equilibrium radionuclide ventriculography and its application to the functional and prognostic characterisation of patients with valvular diseases will be discussed.

[Scintigraphic diagnosis of inflammation and infection].

Nuclear medicine, diagnostic and therapeutic application of open sources of ionizing radiation in medicine, has wide range of possibilities for non-invasive infection and inflammation detection. The broad spectrum of methods, some of which are already in routine use while the others are still in the phase of investigation, improvement, or clinical trials, is presented. Most of the methods in routine use are capable of detection and localisation of both inflammation and infection. Antibiotic and antimicrobe peptides labelings have the possibility to diagnose infection and to differentiate it from inflammation, which is not the case with other scintigraphic methods. Availability of the radiopharmaceuticals and nuclear-medicine equipment, radiation exposure of the patient, clinical situation, the baseline pathophysiology of a process, and costs are the factors which contribute to the choice of the diagnostic approach. In order to ease the choice of the appropriate diagnostic method for inflammation/infection detection in different clinical situations, the recommendations from the ISORBE (International Society of Radiolabelled Blood Elements) are quoted.

[Radionuclide detection of Helicobacter pylori infection].

The aim is the assessment of the HP infection in stomach using breath test and comparison to other diagnostic methods, as well as following up the effect of therapy. In 83 patients with digestive discomfort rapid urease test, histology and breath test were performed, while in 25 patients with proven HP infection the effect of therapy was followed up using breath test and clinical findings. For rapid urease test and histology, samples were taken from antral mucosa. Breath test was performed after per oral administration of the capsule of 14C- urea (37 kBq) (Izotop, Hungary and Laboratory for radioactive isotopes, Vinca) which, in the presence of Helicobacter pylori breaks up to 14CO2 and NH3. Radioactivity was measured by beta counter in the exhaled air fasting and 30 minutes after ingestion of the capsule. According to our results, the rise of activity over 100% was considered positive. From 83 patients, 58 were breath test was positive, 24 negative and one equivocal. Fast urease test was in 54 positive, in 29 negative while histology was in 57 postitive and 26 negative. Findings of the breath and urease tests were in accordance in 93% patients while breath test and histology in 98% patients. During follow up of the therapeutic effects, breath test and clinical findings were in accordance in 98% patients. Breath test can be useful in diagnosis but is a method of choice in following up the patients after therapy for H. pylori infection, because it is non-invasive, fast and precise.

[Implementation of the radiolabelled antibiotic in the detection of orthopedic infections].

The aim of the study is detection and evaluation of the orthopedic infections using 99mTc-ciprofloxacin, radiopharmaceutical supposed to distinguish inflammation from infection. There were 15 true positive findings, 9 true negative, and two were false positive, while 1 was false negative. Sensitivity was 94%, specificity 82%, positive predictive value 88%, negative predictive value 90% and accuracy 89%. According to our results, scintigraphy with 99mTc-ciprofloxacin is a useful method for detection and assessment of exact localization of orthopedic infections, which might be useful for (differential) diagnosis, surgical treatment in due time as well as monitoring of the treatment of conservative therapy.

[Initial 111In-platelet kinetics: indicator of platelet sequestration/destruction site or quality control of platelet labelling?].

Taking into consideration the existing disagreement in the literature, the aim of this paper was to estimate the value of the initial kinetics of autologous platelets labelled with 111In-oxinate, performed during the first 20 minutes after their intravenous injection. Two hypothesis were tested: 1. Initial 111In-platelet kinetics indicates the platelet sequestration site (in patients with normal mean platelet life span)/destruction site (in patients with shortened mean platelet life span), 2. Initial 111In-platelet kinetics indicates the quality of platelet separation and labelling procedure. We performed initial labelled platelet kinetics in thrombocytopenic patients (in order to test the first hypothesis) as well as in control (healthy) subjects (in order to test the second hypothesis). Thirty-nine persons were investigated: 33 with thrombocytopenia: 25 with shortened mean platelet life span, caused by chronic im mune thrombocytopenic purpura (ITP), eight with normal platelet life span and thrombocytopenia caused by myelodysplastic syndrome (MDS), six healthy, control subjects (C). In all 39 persons platelet blood count on the day of platelet labelling was determined, autologous platelet labelling with 111In-oxinate was performed, general and differential yields of platelet labelling (GYL and DYL), as well as mean labelled platelets life span were determined. Besides that, initial labelled platelets kinetics was performed with initial 111In-platelets accumulation in the liver (IPAL) calculation, as well as the late platelet kinetics for platelet sequestration index and platelet sequestration/destruction site determination. We obtained two types of initial labelled platelets kinetics (not only in the patients with shortened platelet life span, but also in the subjects with normal labelled platelets life span), which differed in the IPAL value and in the ratio of the liver and the heart radioactivity: IPAL < 20% and IPAL>20%. We found statistically significant difference in GYL and DYL between the two groups: IPAL<20% and IPAL > 20%. Both yields were higher in IPAL<20% group. There was no significant difference between the two IPAL groups in the platelet blood count, labelled platelet life span, sequestration index and sequestration site. No correlation could be found between IPAL on one side and platelet blood count, sequestration index, and sequestration site on another. We concluded that initial labelled platelet kinetics could not indicate the platelet sequestration/destructon site (which is accomplished by the late labelled platelets kinetics), but nevertheless, it is very sensitive and useful method of platelet separation and labelling quality control. While in vitro quality control parameters (GYL and DYL) indicate the quality of only one part of this procedure, initial labelled platelet kinetics reflects discrete platelet function disturbance that might happen from the moment of blood sample collection till the labelled platelets intravenous injection.

[Prediction of the splenectomy efficacy in chronic immune thrombocytopenic purpura].

The aim of this investigation was to estimate the possibility of predicting the splenectomy response in patients with chronic immune thrombocytopenic purpura (ITP). The patients' age, sex, megakaryocytes abundance, platelet blood count, production, life span, sequestration/destruction site were considered as possible predictive factors. Thirty-four ITP patients (23 female and 11 male) aged from five to 83 years were investigated. Platelet blood count ranged from 4 to 106 x 10(9)l (mean value was 43 x 10(9)/l). Megakaryocyte abundance was determined in 19/34 ITP patients. Megakaryocytes were numerous in 11/19, present in 7/19 ITP patients and in one patient low megakaryocyte number was registered. In all 34 ITP patients autologous platelet labelling with 111In-oxinate was performed and labelled platelets were reinjected to the ITP patients. This enabled platelet life span, production, sequestration index and sequestration/destruction site determination. Platelet life span ranged from 0,4-5 days (mean value was 1 day). Mean value for platelet production index was 1,1. Platelet sequestration/destruction site in 16 ITP patients was the spleen, and in two it was the liver. Mixed platelet sequestration/destruction site (the liver and the spleen) was registered in 7 ITP patients, while predominantly splenic sequestration/destruction was present in 9 ITP patients. All 34 ITP patients were later submitted to splenectomy, which is a therapeutic option in ITP. Splenectomy result was favorable in 28/34 ITP patients while it was unfavorable in 6/34 (17,6%). Highly significant correlation was noticed between the splenectomy result and platelet sequestration site (p < 0.01). On the other hand, there was no correlation between the splenectomy result on one side, and patient's age, sex, megakaryocyte abundance, platelet production, life span and blood count on the other. Splenectomy result was favorable in all ITP patients with splenic sequestration/detruction of labelled platelets. It was unfavorable in ITP patients with hepatic sequestration of labelled platelets. In ITP patients with mixed platelet sequestration (hepatic and splenic) there were more unfavorable than favorable splenectomy results. Non-invasive method of platelet labelling and platelet sequestration/ /destruction site determination makes easier the clinicians' and ITP patients' decision for the splenectomy in the case when the spleen is the only sequestration site of the labelled platelets, and against the splenectomy, when exclusively hepatic platelet sequestration/destruction is registered.

[Liver hemangioma blood pool as a function of time].

UNLABELLED: Aim of the study was to determine the time needed for establishing maximal labelled red blood cell concentration in hemangioma by scintigraphic semiquantitative blood pool estimation as a function of time. PATIENTS AND METHODS: Eleven patients (eight females and three males) with total number of fourteen liver hemangiomas have been examined. Nine of them had solitary lesions and remaininig two patients had two and three liver hemangiomas, respectively. All patients underwent blood pool scintigraphy 40, 60, 120 and 180 minutes after in vivo labelling of autologous red blood cells using 740 MBq of 99mTc. After correction for radioactive decay of 99mTc and back-ground correction blood pool indexes, as hemangioma/heart and liver/heart counting rate ratios, have been calculated. RESULTS: Mean blood pool indexes obtained 40-180 minutes after in vivo red blood cell labelling did not differ significantly (p > 0.05) neither in hemangioma (0.84-0.86) nor in liver tissue (0.55-0.58). In every acquisition time hemangioma blood pool index was substantialy higher than that of liver tissue (p < 0.01). CONCLUSION: The results of the study indicates that labelled red blood cells concentration reaches its plateau before 40th minute following in vivo labelling. The concentration difference between hemangioma and liver tissue also does not differ significantly after 40th minute of blood pool examination. In most patients blood pool scintigrams taken 60, 120 and 180 minutes following in vivo RBC labelling do not contribute to diagnostic value of the method.

A new radionuclide approach for the quantification of left ventricular volumes: the 'geometric count based' method.

A new radionuclide method, called the 'geometric count based' (GCB) method, has been developed for the quantification of absolute left ventricular volume. As the method is based on planar radionuclide ventriculography, it is non-invasive and simple, and avoids the relatively cumbersome and longer lasting, dynamic procedure using single photon computed emission tomography, which can be used for achieving the same goal. The purpose of this study was to describe the exactness of the theoretical approach to the method and validate its accuracy both by physical experiments and the initial clinical trial, as compared to contrast ventriculography. Count based data were combined with the geometric based data assuming an ellipsoid left ventricular shape with identical short axes. The following equation for computing left ventricular end diastolic volume, EDV (in ml) was developed: EDV=2cMCtot/Cmax, where c is the manually drawn short axis (one row pixel ROI) of the prolate ellipsoid in LAO 45 degrees (cm), M is the calibrated pixel size (in cm2), Ctot is the total counts in LV ROI, and Cmax is the maximum pixel counts in the LV ROI. Physical experiments with two different 'heart shaped' phantoms were used to compare the results obtained by the GCB method with the true phantom volumes and with the method assuming LV ball shape (BLV), developed by other authors. The true volumes of cylindrical and ellipsoid phantoms of 112.5 ml and 190.5 ml were computed to be 114 ml and 196 ml by the GCB and 168 ml and 180 ml by the BLV methods, respectively. In a clinical study, GCB volumes were compared to volumes measured by using single plane contrast ventriculography in 38 coronary patients. A good correlation between the GCB method and contrast ventriculography was obtained both for EDV and end systolic ventricular volumes (r=0.94, r=0.90). Both phantom and initial clinical studies indicate that the GCB method is an accurate, non-invasive and simple radionuclide method for measuring left ventricular volumes. Additionally, it could be used even in the smallest nuclear medicine units, for example in intensive care units where there are mobile cameras.

Prognostic value of myocardial viability determined by a 201Tl SPECT study in patients with previous myocardial infarction and mild-to-moderate myocardial dysfunction.

The prognostic meaning of myocardial viability is most important in patients with severe left ventricular dysfunction and ischaemic heart disease, but its prognostic significance in patients with previous myocardial infarction and mild-to-moderate myocardial dysfunction is uncertain. The aim of this study was to assess the prognostic value of a 201Tl single photon emission computed tomography (SPECT) rest-redistribution study in patients with previous myocardial infarction, ischaemic heart disease and mild-to-moderate myocardial dysfunction. Myocardial viability was assessed in 55 patients (50 male; mean age 58+/-9 years) by 201Tl SPECT rest-redistribution (after 4 h) scintigraphy. All patients had previous myocardial infarction (>3 months) and angiographically documented coronary artery disease, with the mean ejection fraction of 43+/-10%. Out of 55 patients, 20 were medically treated and 35 were revascularized. The follow-up period for adverse cardiac events, including death and non-fatal myocardial infarction, was 12 months. 201Tl SPECT study was positive for myocardial viability in 36 patients (65%) and negative in 19 patients (35%). Sensitivity, specificity, positive and negative predictive values for functional improvement in the follow-up period were 85%, 75%, 92% and 60%. Out of seven (13%) cardiac events in the follow-up period (four cardiac deaths and three reinfarctions), five occurred in 20 medically treated patients and two in 35 revascularized patients (25% vs 6%, P <0.05). Absence of myocardial viability was the only variable associated with adverse cardiac events (P =0.02). Survival at 12 months, as determined by using Kaplan-Meier analysis, was 56% for medically treated and non-viable patients, 80% for revascularized and non-viable patients, 91% for medically treated and viable patients, and 100% for revascularized and viable patients (P =0.0034). These findings suggest that in patients with previous myocardial infarction and mild-to-moderate myocardial dysfunction, the absence of myocardial viability as determined by the 201Tl SPECT study was the only variable associated with adverse cardiac events. The best 12 month survival was observed in revascularized viable patients, whereas the worse prognosis was found in non-viable, medically treated patients.

[Detection of abdominal infections using radio-labeled antibiotics]. / Otkrivanje infekcija u abdomenu primenom radioobelezenog antibiotika.

The aim of the study is detection of the abdominal infective foci using 99mTc-ciprofloxacin, radiopharmaceutical supposed to distinguish inflammation from infection. Twenty-one patient was investigated. There were 11 true positive findings, 7 true negative, two were false negative, while 1 was false positive. Sensitivity of the method was 79% and specificity 91%. According to our results, scintigraphy with infection is a useful method for detection and assessment of exact localization of deep seated bacterial infections, which might be useful for (differential) diagnosis, surgical treatment in due time as well as monitoring of the treatment of conservative therapy.

Pharmacological radionuclide ventriculography for detection of myocardial contractile reserve in patients after myocardial infarction: head-to-head comparison of low dose dobutamine and low dose dipyridamole.

BACKGROUND: Low dose pharmacological stress echocardiography with either dobutamine or dipyridamole infusion has been proposed for recognition of myocardial viability. However, dependence on adequate acoustic window, observer experience, and the mild degree of wall motion changes make the viability assessment by stress echocardiography especially bothersome. The objective of the study was to evaluate the ability of low dose dobutamine and low dose dipyridamole radionuclide ventriculography to detect contractile reserve in patients after myocardial infarction and functional recovery after coronary angioplasty. METHODS: The study group consisted of 20 consecutive patients (52 +/- 10 years, 17 male, 3 female) with previous myocardial infarction and resting regional dyssynergy, in whom diagnostic cardiac catheterization revealed significant one-vessel coronary artery stenosis suitable for angioplasty. Each patient underwent equilibrium 99m-Tc radionuclide ventriculography which was performed at rest and during low dose dipyridamole (0.28 mg/kg over 2 minutes) and low dose dobutamine infusion (up to 10 mcg/kg/min). Left ventricular global and regional ejection fractions were determined. Increase of regional ejection fraction for > 5% (inferoapical and posterolateral regions) or > 10% (anteroseptal regions) during low dose dobutamine and dipyridamole in infarcted regions, as well as in the followup period, was considered as index of contractile reserve. After 8 weeks of successful angioplasty, resting radionuclide ventriculography was repeated in all patients in order to identify functional recovery of the infarct zone. RESULTS: Out of the 180 analyzed segments (20 x 9), 90 regional ejection fractions have shown depressed contractility. The mean of the regional ejection fractions showing depressed contractility increased from the resting value of 34 +/- 12% to 42 +/- 14% in the follow-up period (p = 0.06). Of the 90 with baseline dyssynergy, 46 were responders during low-dose dobutamine (51%), whereas 32 segments were responders (36%, p = 0.05 vs. dobutamine) during low dose dipyridamole. Positive predictive value of dobutamine and dipyridamole for predicting functional recovery was 72% and 75% (p = ns), respectively. Negative predictive value of dobutamine and dipyridamole was 48% and 69% (p = 0.05), respectively. In the group of patients with most severe dyskinesia (regional ejection fraction < 35%, 42 segments) positive predictive value was 73% and 82%, while negative predictive value was 42% and 64% for low dose dobutamine and low dose dipyridamole respectively (p = ns). CONCLUSION: Although low dose dobutamine induced higher rate of positive responses during radionuclide ventriculography imaging, dipyridamole radionuclide ventriculography has shown superior, particularly negative, prognostic value for predicting functional recovery of infarcted regions.

An expert system approach for the objective interpretation of serum tumour marker levels.

The aim of our work was to study specific aspects of statistical Weinstein-Bayes's analysis in order to find the most suitable program for presenting our results and for obtaining information which could be used as a guide in the clinical decision-making process. Our efforts resulted in a computer processing system based on modified Weinstein-Bayes receiver operating characteristics (ROC) analysis. The data analysis provides numeric values of sensitivity, specificity, positive predictive value and negative predictive values as output tumour marker databases, which would serve as graphic input. It becomes possible to plot the ROC curve as a graphical distribution of tumour marker levels. The computer program also allows the estimation of the potential utility of the serum tumour marker measured in patients with various diseases, simultaneous determination of serum tumour markers in diseased patients, and the real value of each serum tumour marker level in diseased patients.

Implementation of a personal computer (PC) as a graphic station into the system MicroDELTA-MaxDELTA for processing of nuclear medicine images.

One of the possibilities to integrate PC into the system "MicroDELTA-MaxDELTA" for acquisition and nuclear medicine image processing is introduced. A 386 IBM compatible personal computer is connected into the local area network with MicroVAX II, which is the part of a "MicroDELTA-MaxDELTA" system. "NuMed" application, which enables simple and efficient manipulation of patient studies and also their archiving, processing and generating reports, is developed in WINDOWS environment. Considering the fact that existing system fully satisfies the acquisition requirements, the whole conception has the aim to upgrade the digital image processing, and initiate further development of the whole system.

201Tl reinjection and late redistribution in the detection of viable myocardium.

Nonreversible (NRD) myocardial perfusion defects following stress-rest (S/R) 201Tl studies may often be found in ischemic areas. 201Tl reinjection immediately following S/R scintigraphy and 24h (late) redistribution has been shown to identify late reversible defects (LRD) indicative of viable myocardium. Twenty two patients with CAD were studied. All subjects underwent S/R 201Tl (37MBq) 24h later (1 group). Six out of 22 patients had late scintigraphy without new doses of 201Tl. Ischemia was considered present when the poststress count density was less for more than 25% than the resting count density. Out of 29 NRDs. 15 segments exhibited late reversibility following 201Tl reinjection reflecting viability (II group). One out of 8 NRDs demonstrated late reversibility following late redistribution imaging (II group). Thus, 201Tl reinjection following S/R imaging appeared to be more effective in maximizing the detection of viable myocardium than late redistribution. It is equally useful in patients with NRD following S/R scintigraphy and no history of prior myocardial infarction (MI) or those who had MI.

Measuring of cardiolipin antibodies and plasma lipids in different stages of coronary disease.

The study shows that antibodies to cardiolipin which are commonly found in young postinfarction cases may present a high risk for recurrent coronary manifestations. IgG and IgM antibodies to cardiolipin (C1Ab) were determined in 50 healthy individuals and 72 patients with coronary disease: 26 with acute infarction (A) and 24 with chronic infarction (C) as well as 22 with angina pectoris (AP). Lipid status parameters as risk factors were measured in all patients: total cholesterol, LDL, HDL cholesterol, triglycerides and apolipoprotein (a). Out of 72 patients suffering from coronary disease 20 (27.7%) had elevated C1Ab IgG (12.36 +/- 3.7 GPLU/ml). Rise of C1Ab IgM was not evidenced in any of the patients. C1Ab IgG were significantly elevated (p < 0.01) in patients with chronic myocardial infarction and angina pectoris (p < 0.05) while in cases of acute myocardial infarction significant elevation of these antibodies was not evidenced.

Targeting of non-small cell lung cancer using HMFG1-99mTc monoclonal antibodies.

Anti HMFG1 monoclonal antibodies labeled with 99mTc were used for the detection of non-small cell lung cancers and their metastases in 18 patients (12 squamous cell cancers, 2 large cell lung cancers, 1 adenocarcinoma and 3 undifferentiated non-small cell lung cancer). According to performed therapy all patients were divided into three groups: group 1 consisted of 13 patients who had not received chemotherapy or radiotherapy before immunoscintigraphy (IS), group 2 included 3 patients who had undergone IS during external beam radiotherapy, and group 3 (two patients) who had received both chemotherapy and radiotherapy before IS. After antibody administration planar scintigraphy of the head and neck, chest in anterior and posterior projection, anterior abdomen, pelvis, thighs and calves was obtained at 10 minutes, 5 hours and 24 hours. The scans were interpreted semi-quantitatively using T/NT ratio. In the first group IS was found true positive in 5/13 patients (38%), and T/NT ratio ranged from 1.3-1.5. In the second group all three patients were true positive and T/NT ratio ranged from 1.76 to 2.1. In the third group both patients were found false negative. Successful metastases detection was found in 4/13 patients (30%).

Application of 99mTc-DTPA aerosol in evaluation of pulmonary epithelial permeability.

Measuring of the rate of radioactivity decrease of inhaled 99mTc-DTPA aerosol may detect disorders of alveocapillary membrane integrity. The study included 21 patients (11 non-smokers and 10 smokers) suffering from different pulmonary diseases (pulmonary embolism - PE; chronic obstructive pulmonary disease - COPD; pneumonia - PN; occupational diseases - OD) in order to detect disorders of pulmonary epithelial permeability (PEP) and 2 healthy individuals (non-smokers) with normal findings (NF). DTPA was labelled using the standard procedure with 1480 MBq 99mTc in 1 ml of physiologic saline. Patients with nasal obstruction inhaled aerosol for 2.5 min. particle size 0.8 micron produced in a nebulizer connected to O2. After that gamma scintillation camera and computer were used for data acquiring in dynamic mode. After that ventilation and perfusion scintigraphy of the lungs was performed in four standard projections. Data processing was conducted with ROI drawing after both lungs on the added image. Clearance value was expressed in T1/2 (min), while the curves had monoexponential shape in all patients. In the non-smoking group mean clearance value for both lungs in patients suffering from PE, COPD and PN did not differ from NF. Clearance in the part of the lungs affected with disease (pneumonia, embolism) was faster than in healthy pulmonary tissue. In sick smokers, however, mean pulmonary clearance value was higher than in non-smokers, irrespective of the type of disease. Pulmonary clearance in individuals suffering from occupational diseases was also accelerated, irrespective of the fact whether the patients smoked or not.

Determining the lifespan of platelets labelled with 111In oxinate--first results.

The paper presents the new method of platelet labelling, quality control of separation and labelling, as well as the investigation of the 111In oxinate labelled platelets lifespan. Among the 23 investigated persons, there were 4 hematologically healthy persons and 19 ITP patients. Homologous and autologous labellings were done in one and 22 persons, respectively. Determination of the platelet lifespan in healthy subjects enabled the estimation of "in vitro" procedures of separation and labelling, as well as "in vivo" behaviour of the labelled platelets. Our results show that 111In oxinate labelled platelets have normal lifespan (8.9 +/- 0.6 days), which means that the procedure of separation and labelling does not damage them. In the ITP patients the platelet lifespan is shortened (0.4-4.6 days), which confirms the mechanism of thrombocytopenia. In the subject where homologous labelling had been done, we found out the existence of sensibilisation toward the donor platelets, which lead to the correction of therapy.

[Use of the positron emitter in functional and metabolic lung studies]. / Primena pozitronskih emitera u funkcionim i metabolickim ispitivanjima pluca.

Positron emission tomography (PET), a new technique, uses positrons which, immediately after emission, combine with electrons and annihilate to produce pairs of 511 KeV photons. Commonly used positron emitters (C-11, N-13, O-15) are important constituents of biologic metabolism. However, because of their short half-life characteristics, the on-side cyclotron facility is required for their use. To date, there is not much experience with PET in lung diseases. In this paper brief information about PET application in pulmonary blood flow measurements, ventilation measurement, central chemical control of ventilation and lung metabolic studies, is presented.