Search

Background Bronchoscopy serves as direct visualisation of the airway. Virtual bronchoscopy provides similar visual information using a non-invasive imaging procedure(s). Early and accurate image-guided diagnosis requires the possible highest performance, which might be approximated by combining anatomical and functional imaging. This communication describes an advanced functional virtual bronchoscopic (fVB) method based on the registration of PET images to high-resolution diagnostic CT images instead of low-dose CT images of lower resolution obtained from PET/CT scans. PET/CT and diagnostic CT data were collected from 22 oncological patients to develop a computer-aided high-precision fVB. Registration of segmented images was performed using elastix. Results For virtual bronchoscopy, we used an in-house developed segmentation method. The quality of low- and high-dose CT image registrations was characterised by expert’s scoring the spatial distance of manually paired corresponding points and by eight voxel intensity-based (dis)similarity parameters. The distribution of (dis)similarity parameter correlating best with anatomic scoring was bootstrapped, and 95% confidence intervals were calculated separately for acceptable and insufficient registrations. We showed that mutual information (MI) of the eight investigated (dis)similarity parameters displayed the closest correlation with the anatomy-based distance metrics used to characterise the quality of image registrations. The 95% confidence intervals of the bootstrapped MI distribution were [0.15, 0.22] and [0.28, 0.37] for insufficient and acceptable registrations, respectively. In case of any new patient, a calculated MI value of registered low- and high-dose CT image pair within the [0.28, 0.37] or the [0.15, 0.22] interval would suggest acceptance or rejection, respectively, serving as an aid for the radiologist. Conclusion A computer-aided solution was proposed in order to reduce reliance on radiologist’s contribution for the approval of acceptable image registrations.

LB

Background Long-term survival of xenogeneic transplanted cells in adults requires strong immunosuppression and/or encapsulation of the cells to achieve peripheral transplant tolerance. Purpose The aim of our project was to seed decellularized tissue engineered heart valves (TEHV) with xenogeneic (porcine) mesenchymal stem cells (pMSCs) transfected transiently (Lipofectamine) with a positron emission tomography (PET)-reporter gene (pMSC-PETr), followed by implantation as pulmonary valve replacement into sheep without immunosuppression. The fate of the seeded pMSC-PETr was tracked via serial in-vivo non-invasive PET-computed tomography (PET-CT). Methods Static cultivation of TEHV scaffold led to successful ingrowth of the pMSC-PETr. For enabling quantitative assessment of viable pMSC-PETr in the TEHV scaffold after in vivo implantation, vials containing 5x104, 2x105, and 4x105 pMSC-PETr were in vitro mixed with the [18F]-FHBG PET tracer for 1 hr, then the non-bound tracer was washed out and vials were in vitro PET-CT imaged, giving reference values. TEHV-pMSC-PETr were then implanted percutaneously into the pulmonary valve position of sheep (n=4) under general anesthesia, while an additional sheep with no valve implantation served as a control. Ten mCi of [18F]-FHBGPET radiotracer was produced for each procedure and serial PET-CT imaging of the sheep was performed at 3 hr, 24 hr, 2 or 3 weeks, and 5 and 6 months after valve implantation. The study followed the Principles of laboratory animal care. Results PET-CT of vials containing increasing number of pMSC-PETr showed dose-dependent tracer uptake in the transfected cells in vitro (Figure). PET-CT images of the sheep 3 hr after implantation of the TEHV-pMSC-PETr showed a clear signal of transfected cells, with a mean estimated number of viable pMSC-PETr of 5.18±1.19x106. No meaningful decrease of the amount of living cells occurred at 24 hr or 2 or 3 weeks. Interestingly, 5- and 6-month follow-up PET-CT images showed clear in vivo and in vitro (after explantation) PET signals of the pMSC-PETr on TEHV, indicating spontaneous stable transfection of the PET reporter plasmid (insertional mutagenesis). Histology confirmed the survival of the pMSC-PETr at 5 and 6-month after xenogeneic transplantation. Merged immunohistochemistry and fluorescence imaging of anti-pig SLA I and anti-sheep MHC I antibodies and PET-reporter gene (HSV1-tk) suggested in vivo inter-species lateral jump gene transfer between pig MSCs and host sheep cells. Figure 1 Conclusions This is the first report on serial non-invasive in vivo tracking of long-term survival of xenogeneic pMSCs-PETr seeded on TEHVs and percutaneously implanted into the pulmonary position of sheep. Long-term follow-up revealed spontaneous stable transfection of the plasmid PET-reporter gene, which suggests the risk of insertional mutagenesis induced by the plasmid (transposon), and PET-reporter gene shuttle from xenogeneic pig MSCs to sheep cells. Acknowledgement/Funding LifeValve EU project (grant number: 242008)

The aim of this study is to support medical experts to be able to make an order among large number of automatic registration. The experts could tackle with the most problematic cases due to the inaccuracy of automatic registration procedure in the vicinity of the bronchus to help virtual bronchoscopy (VB) systems. Functional images (e.g. PET) can be projected on the relevant part of the organ that is examined in VB systems. We collected cases where the difference between the time of low-dose (ldCT) and diagnostic CT (hdCT) was less than one year. Altogether 22 anonymous ldCT and hdCT studies were selected in this study. Based on the literature, a potential candidate for image registration was elastix. We applied a specific in-house developed application for image preprocessing, before the elastix registration. We tried to resolve the goodness of the entire registration process by visual judgment combining it with special numerical features. Numerical data include the mutual information, standardized mutual information, Kullback-Leibler entropy, cross correlation, L1norm, L2norm square. We found satisfying correlation between mutual information and visual judgment in the close vicintiy of airtree. We calculated confident intervals for MI of acceptable and rejected registrations about the mean values of it by bootstraping method: [0.27, 0.36], [0.13, 0.19].

[EN] To find structural differences between brain metastases of lung and breast cancer, computing their heterogeneity parameters by means of both 2D and 3D texture analysis (TA). Patients with 58 brain metastases from breast (26) and lung cancer (32) were examined by MR imaging. Brain lesions were manually delineated by 2D ROIs on the slices of contrast-enhanced T1-weighted (CET1) images, and local binary patterns (LBP) maps were created from each region. Histogram-based (minimum, maximum, mean, standard deviation, and variance), and co-occurrence matrix-based (contrast, correlation, energy, entropy, and homogeneity) 2D, weighted average of the 2D slices, and true 3D TA were obtained on the CET1 images and LBP maps. For LBP maps and 2D TA contrast, correlation, energy, and homogeneity were identified as statistically different heterogeneity parameters (SDHPs) between lung and breast metastasis. The weighted 3D TA identified entropy as an additional SDHP. Only two texture indexes (TI) were significantly different with true 3D TA: entropy and energy. All these TIs discriminated between the two tumor types significantly by ROC analysis. For the CET1 images there was no SDHP at all by 3D TA. Our results indicate that the used textural analysis methods may help with discriminating between brain metastases of different primary tumors., This work was supported in part by the Spanish Ministerio de Economia y Competitividad (MINECO) and FEDER funds under Grant BFU2015-64380-C2-2-R, by the "Richter Gedeon Talentum Alapitvany" and by the Campus Hungary Mobility Program. Andres Larroza was funded by the Spanish Ministerio de Educacion, Cultura y Deporte (MECD) under Grant FPU12/01140. The authors also thank to the continuous help of Dr. Joaquin Gavila from Fundacion IVO

OBJECTIVE Wall motion abnormalities during acute ST-segment elevation myocardial infarction (STEMI) and the improvement after recanalization depend on the conditions of the coronary occlusion. METHODS Fifty-seven patients with first-ever STEMI due to one-artery occlusion, treated with primary PCI, were evaluated. Area at risk and left ventricular wall motion abnormalities were localized with coronary angiography and echocardiography and then compared in relation to the time elapsed from the onset of symptoms at the time of infarction and at 3 months. Left ventricular diameters and ejection fractions were evaluated in relation to the ischemic time. RESULTS Three hundred forty-one affected left ventricular segments were detected with angiography, while echocardiography showed 206 segments with motion abnormality. No correlation was found between the regional wall motion index in the area at risk and the time elapsed from the beginning of symptoms. However, the improvement in wall motion abnormalities at the follow-up was dependent on the ischemic time (r=-0.29, p

Whole Body PET scans are typically performed as a series of image sets acquired at discrete axial positions to cover most or all of the body. The acquisition time at each axial position is typically kept fixed for all positions although the total imaging time is typically adjusted according to the patient's weight. Because of the varying amount of attenuation for different sections of the body, it is expected that the image Signal-to-Noise (S/N) will vary accordingly. The aim of this work is to investigate the possibility of varying the acquisition time at different sections of the body such that the image S/N is kept relatively constant for all slices. To estimate the acquisition times for the different sections of the body we propose to use the attenuation correction (AC) sinogram generated from the CT scan that is acquired prior to the PET scan. Both simulations and phantom measurements of different diameter cylinders with activity distributions were performed. The image noise was estimated in every pixel from multiple replicate image sets. The image noise was compared to the average AC factors through the center of each body slice. A simple polynomial function was found for both the simulations and the phantom measurement images to accurately describe the image noise as a function of AC factors. These results indicate that the noise properties of whole body images can be made more uniform axially by adjusting the acquisition time according to the amount of attenuation. Instead of using a fixed scan time per bed position, the acquisition time can be reduced in areas of lower attenuation and increased in more absorbing sections of the body. Since there is a strong correlation of the image noise and the AC factors, the relative acquisition times can be quickly calculated using a simple functional relationship.

Expression of multidrug pumps including P-glycoprotein (MDR1, ABCB1) in the plasma membrane of tumor cells often results in decreased intracellular accumulation of anticancer drugs causing serious impediment to successful chemotherapy. It has been shown earlier that combined treatment with UIC2 anti-Pgp monoclonal antibody (mAb) and cyclosporine A (CSA) is an effective way of blocking Pgp function. In the present work we investigated the suitability of four PET tumor diagnostic radiotracers including 2-[18F]fluoro-2-deoxy-D-glucose (18FDG),11C-methionine, 3′-deoxy-3′-[18F]fluorothymidine (18F-FLT), and [18F]fluoroazomycin-arabinofuranoside (18FAZA) forin vivofollow-up of the efficacy of chemotherapy in both Pgp positive (Pgp+) and negative (Pgp−) human tumor xenograft pairs raised in CB-17 SCID mice. Pgp+and Pgp−A2780AD/A2780 human ovarian carcinoma and KB-V1/KB-3-1 human epidermoid adenocarcinoma tumor xenografts were used to study the effect of the treatment with an anticancer drug doxorubicin combined with UIC2 and CSA. The combined treatment resulted in a significant decrease of both the tumor size and the accumulation of the tumor diagnostic tracers in the Pgp+tumors. Our results demonstrate that18FDG,18F-FLT,18FAZA, and11C-methionine are suitable PET tracers for the diagnosis andin vivofollow-up of the efficacy of tumor chemotherapy in both Pgp+and Pgp−human tumor xenografts by miniPET.

The aim of the study is to demonstrate the diagnostic and geographical distribution of the domestic PET/CT examinations financed by the OEP based on the data from the waiting list of the past 4 years. The analysis of the demonstrated data can support the rational usage of PET/CT examination contingents in the domestic oncological attendance, which has growing importance. PET examinations with oncological aims have started in Debrecen more than 10 years ago. In 2005 already 1500 PET examinations have been carried out. According to the governmental regulation accepted in 2006, OEP ensures the financing of the three PET/CT centers until 2012, which means 12,000 examinations in 2012. However, the number of domestic oncological patients requiring PET/CT examinations can reach the number of 20,000-30,000 patients. The study summarizes the number of patients who applied for PET/CT examinations for the first time and later again between 2006 and 2010, based on the data of the waiting list, and the change of the patient assigning diagnosis and the number of examinations carried out with 18F-FDG and with 11C-methionine. The study demonstrates the number of examinations by counties which characterize the population's access to PET/CT. The assigning diagnosis in 2007 was already widespread and focused on problems. After the regulation came in to force in 2008 the possibilities significantly decreased. Clinical cases which were efficiently examined with PET/CT earlier were left out from the indication list. The distribution by county is uneven, although the number of examinations increases year by year. The number of repeated examinations increases as well. As a conclusion, the annual PET/CT examination contingents are constantly exploited. This might seem sufficient, because the method has not become a part of the oncological routine in all counties. Although the current indication list includes the most frequent oncological cases requiring PET/CT, the abandoning of the less frequent ones narrowed the professional latitude, which is disadvantageous for the patients suffering from such diseases. The radiopharmacon supply of PET/CT centers is inadequate thus they cannot provide modern oncological diagnostic attendance in case of frequent types of cancer (such as prostate). In the long run the growing number of repeated PET/CT examinations built in the oncological professional protocol has to be taken into account.

Background— Porcine bone marrow-derived mesenchymal stem cells (MSCs) were stably transfected with a lentiviral vector for transgene expression of the trifusion protein renilla luciferase, red fluorescent protein and herpes simplex truncated thymidine kinase (LV-RL-RFP-tTK; positron emission tomography [PET] reporter gene) for in vivo noninvasive tracking of the intramyocardially delivered MSC fate. Methods and Results— A closed-chest, reperfused myocardial infarction was created in farm pigs. Sixteen days after myocardial infarction, LV-RL-RFP-tTK-MSCs were injected intramyocardially using electromechanical mapping guidance in the infarct border zone (n=7). PET-computed tomographic metabolic and perfusion imaging was performed after an intravenous injection of 10 mCi [18F]-FHBG and 13N-ammonia PET at 30�2 hours and 7 days after LV-RL-RFP-tTK-MSC treatment. Fusion imaging of the [18F]-FHBG PET-computed tomography with MRI was used to determine the myocardial location of the injected LV-RL-RFP-tTK-MSCs. Seven days after injections, [18F]-FHBG PET showed a decreased cardiac uptake with a mild increased pericardial and pleura uptake in the treated animals, which was confirmed by the measurement of luciferase activity. At 10 days, infarct size by MRI in the LV-RL-RFP-tTK-MSC-treated animals was smaller than controls (n=7) (23.3�1.5% versus 30.2�3.5%, P Conclusions— Reporter gene imaging enables the tracking of the persistence of viable LV-RL-RFP-tTK-MSC in the peri-infarcted porcine myocardium at 10 days after delivery using clinical PET scanners.

The aim was to elucidate whether aneurysmal subarachnoid hemorrhage (SAH)-induced vasospasm induces changes of regional glucose uptake in surgically treated, asymptomatic cases.(18)FDG uptake (standardized uptake value, SUV) was analysed with PET in eight surgically treated aneurismal patients with a mean middle cerebral artery flow velocity120 cm/seconds measured with transcranial Doppler ultrasound. Data were compared with a healthy control group using Statistical Parametric Mapping (SPM99b).Six of the eight patients had no focal neurological signs. The inhomogeneous bilateral increase in SUV (p0.0001) was asymmetrical, with an almost 70% larger volume on the operated side. Reduced glucose uptake was found in the frontal and temporobasal regions of the two patients with neurological deficits (p0.0001); the affected volume was 40% larger on the operated side.SAH-induced vasospasm results in widespread increase of glucose uptake-probably reflecting increased glycolysis. This was earlier than neurological focal signs appear. Decreased glucose uptake can be detected in severe cases of vasospasm reflected by neurological deficit. Although the changes are more prominent where surgery had taken place our results suggest that not only the surgery, but also subarachnoid blood might have resulted in our findings.

AIM To study how paclitaxel treatment modifies the accumulation of tumor-diagnostic radiotracers in P-glycoprotein (P-gp) positive and negative cancer cells. METHODS The accumulations of different P-gp substrates, including rhodamine 123, daunorubicin and [(99m)Tc]hexakis-2-methoxybutyl isonitrile ((99m)Tc-MIBI), were measured in P-gp-positive (A2780AD) and P-gp-negative human ovarian carcinoma cells (A2780) and JY human lymphoid B cells. The uptakes of the tumor-diagnostic tracers (11)C-choline and 2-[(18)F]fluoro-2-deoxy-d-glucose ((18)FDG) were measured in the same cell lines. The P-gp expression and function were demonstrated by flow-cytometry. RESULTS The (18)FDG measurements revealed that the glucose metabolic rate was significantly higher (p

Background Membrane potential changes in cells from the human lymphoid B cell line, JY, evoked by increasing cell density in culture were investigated, as data published on other cell types are controversial. An attempt was also made to clear the underlying mechanism. Methods Nonadherent JY cells were isolated from high-density plateau-phase cultures (type A cells), medium-density log-phase cultures (type B cells), and low-density lag-phase cultures (type C cells). They were analyzed for transmembrane potential, intracellular free concentration of potassium and sodium, membrane permeability for monovalent cations, cell cycle distribution by measuring DNA content, and glucose uptake. Results C type cells proved to be relatively depolarized (−41 ± 3 mV) and cells obtained from the highest density cultures hyperpolarized (−60 ± 3 mV). Intracellular concentrations ([K]i = 92–97 mM and [Na]i = 34–35 mM) were almost identical for each type of cell. The sodium/potassium permeability constant ratio in the A and C type of cells was 0.047 and 0.094, respectively. High-density culture conditions resulted in a pronounced G1-phase arrest. Conclusions Differences in the membrane potential values induced by high-density culture conditions were maintained by changes in the membrane permeability for the monovalent cations. Cytometry 41:186-192,2000. © 2000 Wiley-Liss, Inc.

To prove the general applicability of a recently published flow cytometric method to determine the membrane potentials of cells on the absolute (mV) scale, the validity of the premises involved were analyzed individually. Experimental evidence was given for bis-oxonol, the applied membrane potential indicator being a Nernstian dye. The results of special measurements proved that extracellular dye concentrations were not affected by cellular dye uptake under the applied experimental conditions and that the dye content of the suspending medium did not contribute directly to the measured cellular fluorescence. A direct, membrane-potential-independent contribution of the extracellular dye to cellular fluorescence was also found to be negligible, as membrane potential values of the same type of cells evaluated from measurements in the presence of different extracellular oxonol concentrations were very close to each other. The transmembrane potential of B lymphoid JY cells was measured by the method as a function of cell density in the tissue culture. Cells isolated during the log phase of growth displayed a –40±4 mV membrane potential. At a high density of the culture (plateau phase), a significant increase of the membrane potential to –61±3 mV was observed and a medium value of –47±3.5 mV was measured at an intermediate density of the cells. Our observation indicates that nonadherent cells can also be hyperpolarized when optimal growth conditions are terminated.

2-[(18)F]fluoro-2-deoxy-d-glucose ((18)FDG) is a tumor diagnostic radiotracer of great importance in both diagnosing primary and metastatic tumors and in monitoring the efficacy of the treatment. P-glycoprotein (Pgp) is an active transporter that is often expressed in various malignancies either intrinsically or appears later upon disease progression or in response to chemotherapy. Several authors reported that the accumulation of (18)FDG in P-glycoprotein (Pgp) expressing cancer cells (Pgp(+)) and tumors is different from the accumulation of the tracer in Pgp nonexpressing (Pgp(-)) ones, therefore we investigated whether (18)FDG is a substrate or modulator of Pgp pump. Rhodamine 123 (R123) accumulation experiments and ATPase assay were used to detect whether (18)FDG is substrate for Pgp. The accumulation and efflux kinetics of (18)FDG were examined in two different human gynecologic (A2780/A2780AD and KB-3-1/KB-V1) and a mouse fibroblast (3T3 and 3T3MDR1) Pgp(+) and Pgp(-) cancer cell line pairs both in cell suspension and monolayer cultures. We found that (18)FDG and its derivatives did not affect either the R123 accumulation in Pgp(+) cells or the basal and the substrate stimulated ATPase activity of Pgp supporting that they are not substrates or modulators of the pump. Measuring the accumulation and efflux kinetics of (18)FDG in different Pgp(+) and Pgp(-) cell line pairs, we have found that the Pgp(+) cells exhibited significantly higher (p⩽0.01) (18)FDG accumulation and slightly faster (18)FDG efflux kinetics compared to their Pgp(-) counterparts. The above data support the idea that expression of Pgp may increase the energy demand of cells resulting in higher (18)FDG accumulation and faster efflux. We concluded that (18)FDG and its metabolites are not substrates of Pgp.

The relationship between metabolic disorders and the distribution of fat in different body regions is not clearly understood in humans. The aim of this study was to develop a suitable method for assessing the regional distribution of fat deposits and their metabolic effects in dogs. Twenty-five dogs were subjected to computed tomographic (CT) imaging and blood sampling in order to characterise their metabolic status. The different fat areas were measured on a cross-sectional scan, and the animals’ metabolic status was evaluated by measuring fasting glucose, insulin and leptin levels. The volume of visceral adipose tissue is the main determinant of leptin levels. The correlation of visceral fat volume and leptin concentration was found to be independent of insulin levels or the degree of insulin resistance. There was a positive correlation between the visceral to subcutaneous fat volume ratio and serum insulin concentration, and a similar trend was observed in the relationship of fat ratio and insulin resistance. The distribution of body fat essentially influences the metabolic parameters in dogs, but the effects of adiposity differ between humans and dogs. The findings can facilitate a possible extrapolation of results from animal studies to humans with regard to the metabolic consequences of different obesity types.

The osmolality and composition of fish seminal plasma usually suppress sperm motility in the testis and sperm duct. Change in the osmolality of the environment at spawning activates flagellar motion of the sperm tail. The effect of inhibitors of anion and cation channels on active motion was investigated by a microscopic motility test. While sodium channel inhibitors (amiloride and tetrodotoxin) as well as anion channel inhibitors (DIDS and ethacrynic acid) did not affect motility, potassium channel inhibitors (4-AP, quinine, veratrine, verapamil) decreased the duration of flagellar motion or abolished motility completely. Potassium channel inhibitors exerted an effect on sperm motility depending on the dose and length of incubation. The voltage-activated K+ blocker 4-aminopiridine proved to be the most potent inhibitor. Its effect was completely reversible, indicating that the functional state of potassium channels is essential to the activation mechanism of sperm. Intracellular pH of the spermatozoa was measured by a fluorescent flow cytometric technique. Hypo-osmotic shock induced intracellular alkalinization of carp sperm. Increase in pHi was 0.15 pH units. In the presence of 4-AP the measured amplitude and kinetics of the pHi change was the same as in the absence of this inhibitor, arguing against a regulatory role of intracellular pH change.

In the last decade both the number of powerful CT scanners and the number of patient investigations increased with a consequent increase of the patient radiation dose. There are large dose variations (more than 10 fold) among individual CT centers and it remains true if they include the same model of CT scanners. The aim of this study was to compare the patient effective dose (De) during the CT examinations from different manufacturer models presuming the same acquisition protocol and using the imPACT patient organ and effective dose calculator program. The following manufacturers and models were selected in the program: GE (LightSpeed Ultra, LightSpeed 16, LightSpeed Pro 16, LightSpeed VCT), Philips (Brilliance 16, Brilliance 16 Power, Big Bore, Brilliance 64/40) and the Siemens (Emotion 6, Sensation 16, Sensation 16 Straton, Sensation 64, Definition AS). Head and body scans were defined for all cases altering tube voltages, while dose calculations were normalized to 100 mAs X-ray exposure. It was found that in body investigations the calculated De for the GE scans were higher by 20% comparing to Siemens and Philips related values. For the head examinations the differences were larger by almost 55%. We also demonstrated that a power relationship can be found between the De and the tube voltage with the exponent of 3.02±0.14 kV-1 and 2.68±0.14 kV-1 for the body and the head scans respectively. It can be concluded that the patient effective dose could be different in CT examinations using distinct CT scanners but defining the same acquisition protocol. Considering the patient dose, this also means that the scan protocols cannot be transferred between different models without specific investigation.

We carried out spectrofluorimetric and flow cytometric measurements to investigate the effect of hypo-osmotic shock on cell membranes of common carp sperm. The time course of the permeability of the sperm cell membrane, as monitored by DNA-related propidium iodide (PI) fluorescence, was followed for 30 min after dilution of semen in hypo-osmotic environments of different ionic strengths. Spectrofluorimetric measurements indicated a continuous increase in the total PI emission intensity of a sperm suspension. Cell-by-cell flow cytometric measurements suggested that the permeability changes were of the all-or-none type. The permeabilized fraction of cells in the individual samples was time and osmolality dependent. The number and percentage of cells in which DNA was stained by PI increased gradually over time and reached a steady-state plateau value after 5-15 min. This equilibrium fraction of cells with a PI-permeable cytoplasmic membrane displayed an inverse relationship with the osmolality of the diluent, having a near 100% value for fresh water and distilled water. Dilution of sperm in hypo-osmotic medium brought about a fast decrease in the forward light-scattering signal on a short time scale compared to the pre-steady-state time of the permeabilization. With the addition of extracellular Ca2+ (1.8 mM), restoration of the light scattering signal was observed. Permeabilization of the membrane and restoration of light scattering were not coincident in time. We propose a two-dimensional reorganization of the lipid structure as the underlying mechanism of the latter process.

The examination of small animals using high resolution in-vivo imaging methods is a crucial tool in pharmaceutical research projects. These type of studies frequently require the measurement of very low activity lesions in a background region or high activity body parts for instance in case of dynamic investigations. To suffice these demands, two independent qualities of the PET scanner need to be appropriate, the low count detectability and the count rate performance. In our study we investigated the detectability of the low level activity area using our LYSO based small animal PET camera. The minimum detectable activity (MDA) was evaluated by the Currie equation and by taking into account the scanner recovery coefficient for different source diameters. We used two different water fillable cylindrical phantoms, the radius and the length of the cylinders are 15 mm and 50 mm, respectively. The phantom I includes five teflon (water density) rods with different diameter (0.5, 1.5, 2.5, 4, 6.5 mm). The phantom II includes tree glass rods with diameter of 0.5 mm. Filling the same F18 activity concentration to the rods of phantom I., the background (cylinder) region we injected C11 activity. This way we could examine different target to background ratios (T/B) simply. We found that the MDA depends on the actual background level and the size of the object. We also found that only the RC corrected MDA∗ values and related points correspond to the real detectability (visibility). The smallest rod (diameter = 0.5 mm) could not be imaged by our mini PET scanner with the activity range we used in this study.

Polar map display (PM) is a comprehensive interpretation of the left ventricle. This is a non-rigid registration of the left ventricle originally for the visual and quantitative analysis of tomographic myocardial perfusion scintigrams. In this scheme the maximal-count circumferential profiles of well-defined short- and long-axis planes are plotted to a map showing the distribution of the perfusion tracer onto a two-dimensional polar representation. The usual coronary artery distribution is often indicated on the PMs of SPECT studies by referring to the regions of the three main coronary branches, nevertheless, the individual variations may differ extensively. We set out to develop an Access (Microsoft)-based computer program that permits an integrated evaluation of the imaging results (coronary angiography, echocardiography and SPECT) on patients with coronary artery disease. This semi-quantitative registration of the coronary tree to a PM focused on the relation between the supplying coronary branches and the myocardial regions of the 16-segment left ventricular evaluating model. All the recorded anatomical and functional data were related to these 16 left ventricular segments, which allowed the direct comparison and holistic synthesis of the results. Two projections were taken into consideration for generation of the coronary PM: from the right anterior oblique projections, the left anterior descendent (LAD)/right coronary artery (RCA) border was assessed through the comparison of the left and right coronary angiograms. The terminations of the visually detected end-arteries showed the separation of the myocardial beds supplied by the two branches. The border of the myocardial beds on the polar map was determined on the "vertical axis" of the local coordinate system. The RCA/ left circumflex (LCx) separation can be determined from the left anterior oblique view. In this projection, the left ventricular septal edge was delineated by the LAD, while the LCx indicated the lateral epicardial surface. The individual coronary artery circulation was typified from among 12 variations in the Holistic Coronary Care program. With this determination of the individual coronary circulation, the lesion-associated segments are generated automatically by the software. The lesion-associated regions are defined as the myocardial bed of a diseased artery distal to the lesion. The PMs generated from the coronary angiographic results were compared with those of 99Tc-labelled MIBI single photon emission computed tomography (SPECT) in order to test the accuracy of the localizing method. The overlap between the segments associated with the coronary lesion and the stress perfusion defects (

An easy to scale up modular PET scanner was developed for imaging small animals. Energy resolution, spatial resolution and count rate performance were determined as system parameters. The configuration provided an average energy resolution of 19.6 % and the image resolution ranges was 1.5 to 2.3 mm in radial direction. The sensitivity of the miniPET was 1.08 cps/kBq as determined using a point source. In addition, results of rat brain scan performed with FDG are given to characterize imaging capability of the system. The displayed data document that the miniPET scanner supports good quality brain imaging of small animals

Aim To establish the effects of Na+/Ca2+ exchanger (NCX) blockers on 2-[18F]fluoro-2-deoxy- d -glucose (18FDG) and 11C-choline accumulation in different cancer cells. Methods The tumor cells were incubated with NCX inhibitors, and the uptakes of 18FDG and 11C-choline were measured. Flow cytometric measurements of intracellular Ca2+ and Na+ concentrations were carried out. The presence of the NCX antigen in the cancer cells was proved by Western blotting, flow cytometry and confocal laser scanning microscopy. Results The NCX is expressed at a noteworthy level in the cytosol and on the cytoplasmic membrane of the examined cells. Incubation of the cells with three chemically unrelated NCX blockers (bepridil, KB-R7943 or 3′,4′-dichlorobenzamil hydrochloride) resulted in an increase in the intracellular Ca2+ concentration, with a simultaneous decrease in the intracellular Na+ concentration. The treatment with the NCX inhibitors increased the energy consumption of the tumor cells by 50–100%. Thapsigargin abolished the NCX-induced 18FDG accumulation in the cells. The NCX blockers applied decreased the 11C-choline accumulation of all the investigated cancer cells by 60–80% relative to the control. Conclusion A possible masking effect of NCX medication must be taken into consideration during the diagnostic interpretation of PET scans.

The pharmacological effects of the neuroprotective drug vinpocetine, administered intravenously in a 14-day long treatment regime, on the cerebral blood flow and cerebral glucose metabolism in chronic ischemic stroke patients (n=13) were studied with positron emission tomography in a double-blind design. The regional and global cerebral metabolic rates of glucose (CMRglc) and cerebral blood flow (CBF) as well as vital physiological parameters, clinical performance scales, and transcranial Doppler parameters were measured before and after the treatment period in patient groups treated with daily intravenous infusion with or without vinpocetine. While the global CMRglc values did not change markedly as a result of the infusion treatment with (n=6) or without (n=7) vinpocetine, the global CBF increased and regional CMRglc and CBF values showed marked changes in several brain structures in both cases, with more accentuated changes when the infusion contained vinpocetine. In the latter case the highest rCBF changes were observed in those structures in which the highest regional uptake of labelled vinpocetine was measured in other PET studies (thalamus and caudate nucleus: increases amounting to 36% and 37%, respectively). The findings indicate that a 2-week long intravenous vinpocetine treatment can contribute effectively to the redistribution of rCBF in chronic ischemic stroke patients. The effects are most pronounced in those brain regions with the highest uptake of the drug.

Miltefosine is a phospholipid analog that exhibits antineoplastic activity against breast cancer metastases, but its mechanism of action remains uncertain. The aim of this study was to investigate the transport mechanism for the removal of miltefosine and [99mTc]-hexakis-2-methoxyisobutyl isonitrile (99mTc-MIBI) from multidrug-resistant cells. The P-glycoprotein pump function, cell viability, and 99mTc-MIBI and 2-[18F]fluoro-2-deoxy-D-glucose (18FDG) uptakes were measured in NIH 3T3 (3T3) and NIH 3T3MDR1 G185 (3T3MDR1) mouse fibroblasts and human lymphoid B JY cells. Miltefosine treatment increased the permeability and fluidity of these tumor cells in a concentration-dependent manner. The multidrug-sensitive cells were 3-4 times more sensitive to miltefosine than the multidrug-resistant ones. The extent of 99mTc-MIBI accumulation in the P-glycoprotein-expressing cells increased in the presence of miltefosine, whereas the rhodamine123 and daunorubicin uptakes of the cells did not change significantly. In the 3T3MDR1 cells verapamil reinstated the rhodamine123 and daunorubicin accumulation, but not the 99mTc-MIBI uptake. Cyclosporin A reinstated the uptakes of 99mTc-MIBI, daunorubicin and rhodamine123 by the 3T3MDR1 cells. In a concentration-dependent manner miltefosine decreased the extents of 99mTc-MIBI, rhodamine123, daunorubicin and 18FDG accumulation in the JY and 3T3 cells. Our findings indicate a common transport mechanism for 99mTc-MIBI and miltefosine, which is distinct from that for rhodamine123 and daunorubicin in MDR cells.

Background We hypothesized that in patients with intracerebral tumours a subcortical metabolical shift may be present when the underlying pathology can, itself, be the epileptogenic focus. We also assumed that by studying the alterations in glucose metabolism beyond the tumour's borders we could identify a modulator area. Methods Sixty-seven patients with supratentorial brain tumour associated epilepsy were investigated interictally, in normoglycaemic conditions, by using [18F]fluorodeoxyglucose positron emission tomography (FDG PET). The studies were analysed semiquantitatively by calculating standardized uptake values and asymmetry indices. Normal subjects and patients with non-epileptic brain lesions were used as controls. Results Compared to normal controls frontal and temporal tumours showed significant changes in thalamic FDG uptake, which reflected hypometabolism of the affected side. It was noted in occipito-medial cortex in temporal tumours and in lentiform nucleus in frontal tumours as well. Comparison to lesional brains only proved that there was significant hypometabolism in lentiform nucleus in temporal tumours. Conclusions The quantified values obviously reflect biological changes. The observed subcortical hypometabolism is most likely secondary to underlying pathology. Although seizures in tumorous patients do not originate from subcortical structures their influence on cortical sites of seizure initiation could be explained by defective subcortical regulation of cortical excitability.

The cerebral projection of vestibular signaling was studied by using PET with a special differential experimental protocol. Caloric vestibular stimulation (CVS)-induced regional cerebral blood flow (rCBF) changes were investigated in two populations. Butanol perfusion scans were carried out on six healthy volunteers and on six patients following the removal of tumors from the right cerebello pontine angle. The complete loss of the vestibular function postoperatively allowed a comparison of the rCBF changes in the populations with or without this input and offered a promising functional approach whereby to delineate the cortical region most responsive to pure vestibular input. The activations by left-sided and right-sided CVS were determined for both the healthy volunteers and the patient population. Statistical analysis of the data obtained following left-sided CVS did not reveal any cerebral region for which there was a significant difference in CVS-induced response by these two populations. In the case of right-sided CVS, however, the statistical comparison of the CVS-related responses demonstrated a single contralateral area characterized by a significantly different degree of response. This cortical area corresponds to part of the cortical region described recently which can be activated by both CVS and neck vibration. It appears to be anatomically identical to the aggregate of the somatosensory area SII and the retroinsular cortex described in primates, a region identified by other investigators as an analog of the parietoinsular vestibular cortex.

P-glycoprotein (Pgp) is an ABC (ATP binding cassette) transporter that is often overexpressed in tumours, contributing significantly to their multidrug resistance. In this study, we explored whether the radiotracers used in tumour diagnostics can be used for in vivo visualisation of Pgp-related multidrug resistance. We also examined the effects of different Pgp modulators on the accumulation of these radioligands in tumours with or without Pgp expression. In a SCID BC-17 mouse model, cells of the drug-sensitive KB-3-1 (MDR(-)) and the KB-V1 Pgp-expressing (MDR(+)) human epidermoid carcinoma cell lines were inoculated to yield tumours in opposite flanks. For in vivo scintigraphic (biodistribution) and positron emission tomography (PET) examinations, the mice were injected with technetium-99m hexakis-2-methoxybutylisonitrile ((99m)Tc-MIBI), carbon-11 labelled methionine and fluorine-18 fluoro-2-deoxy- d-glucose ((18)FDG). For validation, in vitro cell studies with (99m)Tc-MIBI,( 99m)Tc-tetrofosmin, [(11)C]methionine and (18)FDG were carried out using a gamma counter. The expression and function of the MDR product were proved by immunohistochemistry and spectrofluorimetry. (99m)Tc-MIBI uptake was significantly lower in KB-V1 cells as compared with KB-3-1-derived tumours in vivo (Pgp(+)/Pgp(-) =0.61+/-0.13; P0.01) and cells in vitro (Pgp(+)/Pgp(-) =0.08+/-0.01; P0.001).()Cyclosporin A reversed (99m)Tc-MIBI uptake in the Pgp+ cells, while verapamil failed to modify it. (18)FDG uptake was significantly higher in KB-V1 tumours (Pgp(+)/Pgp(-) =1.36+/-0.05; P0.01) and cells (Pgp(+)/Pgp(- )=1.52+/-0.12; P0.001). Whereas cyclosporin A eliminated the difference between FDG uptake in MDR(+) and MDR(-) cell lines, verapamil significantly increased it. When the animals were treated with verapamil, the ratio of (99m)Tc-MIBI uptake in the MDR(+) tumours to that in the MDR(-) tumours decreased to 0.38+/-0.05 ( P0.01), while the ratio of (18)FDG uptake increased to 2.1+/-0.3 ( P0.001). There were no significant differences in the [(11)C]methionine uptake in the MDR(+) and MDR(-) tumours and cell lines, nor was [(11)C]methionine accumulation modified by cyclosporin A. Parallel administration of (18)FDG and (99m)Tc-MIBI combined with verapamil treatment seems to be a good candidate as a non-invasive marker for the diagnosis of MDR-related Pgp expression in tumours.

The coronary angiography giving the morphological data of epicardiac coronary stenoses and non-invasive tests sometimes even together are insufficient for evaluating the functional consequences of the epicardiac coronary stenoses. However, catheterisation allows us to detect the blunting of coronary flow increase during maximal vasodilatation (coronary flow reserve, CFR, e.g. by Doppler flow wire) and by measuring the translesional pressure gradient by pressure wire (fractional flow reserve, FFR) providing accurate functional assessment. According to this concept the authors have developed a complex cardiac database management program (Holistic Coronary Care, HCC). The database has been built on client-server technology where the central object is the 16-segment polar map. The system contains contextual and graphical elements for a quick data entry. By the assessment of 16 left ventricular segments on a polar map display there is a possibility for direct comparison of the invasive functional and morphologic and the non-invasive functional data. Details measured by pressure or Doppler wire are also stored in the coronary evaluating unit and the coronary segments are rendered to the supplied left ventricular segments. For the correct indication of coronary interventions (from functional and financial point of view) it is important to verify unambiguously the functionally significant coronary stenoses. To the best of our knowledge, the necessity of percutan or surgical intervention can be decided the most accurately by FFR and CFR, furthermore CFR objectively shows the failure of the coronary microvasculature.

Access (Microsoft Office)-based software was developed to register the results of different cardiological investigations (echocardiography, coronarography and SPECT) in 16 left ventricular segments in a polar map display in order to compare the anatomical and functional data. Ten patients with previous myocardial infarction were selected (mean age: 48 years, EF: 36.1/spl plusmn/7.2%). They had 14 totally or subtotally occluded coronary branches. The overlap between the occlusion-associated regions derived by angiography and the corresponding defects on MIBI SPECT, and also the echocardiographic segmental wall motion scores were evaluated. The distribution of the total of 160 segments with rest perfusion defects on MIBI SPECT and the wall motion abnormalities detected by echocardiogaphy gave positive and negative predictive values of coronary occlusion of 0.94 and 0.81 against SPECT and 0.82 and 0.76 against echocardiography, respectively. Further analysis revealed that the relative MIBI activities of the individual segments correlated significantly with the wall motion scores (r=-0.87). It is concluded that the direct comparison of tomographic imaging and echocardiography with the angiogram on the polar map display in order to measure the functional consequences of coronary artery disease may help to indicate an intervention on an individual coronary lesion.

A 11C labeled selective adenosine A2A antagonist, (E)-8-(3-chlorostyryl)-1,3-dimethyl-7-[11C]methylxanthine ([11C]CSC) was prepared by the reaction of (E)-8-(3-chlorostyryl)-1,3,-dimethylxanthine and [11C]methyl iodide. The decay-corrected radiochemical yield was 32.3% with a radiochemical purity of 99%, a specific activity of 1.85–5.55 GBq/μmol and a preparation time of 1 h. A primary evaluation of [11C]CSC as a potential tracer for mapping adenosine A2A receptors by positron emission tomography (PET) is also presented. Biodistribution and autoradiographic studies were carried out on Swiss mice and domestic rabbits. In mice the lung showed the highest uptake at 10 min after i.v. injection, followed by the liver, kidney, heart and brain. Inside the brain a high level of radioactivity accumulated in the striatum, in accordance with previous findings on the specific spatial distribution of A2A adenosine receptors and also in the medulla oblongata. Dynamic PET studies on rabbits showed a fast brain uptake of CSC, reaching a maximum in less then 2 min. On the basis of competition experiments with the unlabeled ligand [11C]CSC proves to bind specifically to the appropriate receptor.

In vivo glucose metabolism of the brain was examined using the [18F] fluoro-deoxy-D- glucose (FDG) analogue of the glucose. A relatively high number (20–25) of volumes of interest (VOI) were defined on the PET images. Data of the kinetic studies belonging to these VOI-s were evaluated using the standard uptake value (SUV) method, or calculating glucose metabolic rate (GMR) applying Patlak analysis (PA); and three-compartment model with nonlinear regression (TCM). Correlation of data for all pairs of calculated parameters showed that accurate determination of glucose utilisation in anatomic regions of white matter and those located next to large blood vessels require application of the three-compartment tracer kinetic model calculations with no simplifying assumptions.

The effects of vinpocetine (Cavinton) on the cerebral glucose metabolism of chronic stroke patients are studied with positron emission tomography. The regional and global cerebral metabolic rates of glucose (CMRglu) and the kinetic constants related to them are quantified before and after single-dose intravenous vinpocetine treatment. These measurements are completed with transcranial Doppler sonography and single photon emission computed tomography to explore the possible mechanisms underlying the resulting changes in glucose uptake and metabolism in the brain. The authors' findings indicate that a single-dose vinpocetine treatment, although it does not affect significantly the regional or global metabolic rates of glucose, improves significantly the transport of glucose (both uptake and release) through the blood-brain barrier in the whole brain, the entire contralateral hemisphere, and in the brain tissue around the infarct area of the symptomatic hemisphere. These changes are in accord with increased blood flow in the entire contralateral hemisphere as well as decreased blood flow velocity and increased peripheral vessel resistance in the entire symptomatic hemisphere.

The intracellular pH (pH(i)) of cells exhibiting multidrug resistance (MDR) related to the expression of the P-glycoprotein (Pgp) is often more alkaline than that of the parental cells, as also observed for the KB-V1/KB-3-1 system in this paper. The possible role of an elevated pH(i) in Pgp-related MDR has been investigated by shifting back the pH(i) of the MDR+ cells to a more acidic value using the mobile proton ionophore carbonylcyanide m-chlorophenylhydrazone (CCCP). The influence of CCCP-evoked delta pH(i) on relative daunorubicin (DNR) accumulation was similar in the case of several Pgp positive and negative cell lines, in view of flow cytometric and radioactive drug accumulation studies and measuring DNR levels in the medium in a flow-through system. Our data argue against a significant effect of pH(i) on Pgp pumping efficiency. However, an indirect connection between pH(i) regulation and the MDR phenotype is suggested by the fact that acidification of the external medium in the presence of verpamil could be observed exclusively in MDR+ cells.

We have studied a bretylium tosylate induced increase of the membrane potentials of partially depolarized rat, mouse and human lymphocytes, using the potential sensitive dye, bis [1,3, dibutylbarbituric acid-(5) trimethine oxonol]. The extent of this repolarization is dose-dependent and decreased in magnitude as the temp was reduced from 37 degrees C to room temp. The repolarizing effect is inhibited by K(+)-Na(+)-pump blockers or lack of extracellular Na+. Sodium ion channel blockers are effective in abolishing repolarization only if applied prior to, or simultaneously with, bretylium. Activation of Na+/H+ exchange is not involved in the mechanism of the phenomenon as the latter is completely eliminated in the presence of 10 microM amiloride (concn of the diuretics having no measurable inhibition on the action of the exchanger). These data suggest that bretylium opens ligand- and voltage-gated Na+ channels, and repolarization occurs due to higher activity of the K(+)-Na(+)-pump stimulated by the enhanced intracellular Na+ accumulation.

Bretylium tosylate - a sodium channel opener - resulted in an increase of membrane potential of depolarized human, rat and mouse T and B lymphocytes. Flow cytometric membrane potential measurements with bis-oxonol revealed that the above hyperpolarizing effect was amiloride, ouabain, tetrodotoxin, azide and temperature sensitive. The effect showed an absolute dependence on the extracellular sodium but it was insensitive to the extracellular Ca2+ level. The voltage gating of the effect can be eliminated by either an increase of the extracellular potassium concentration or low doses of veratrin. The existence of a voltage and ligand gated sodium channel is suggested in the plasma membrane of all kinds of lymphocytes. The hyperpolarization is explained by an increased activity of the electrogenic sodium-potassium ATP-ase. Induced opening of such sodium channels may regulate the electrogenic pump activity and indirectly cell activation.

the initial results of human clinical studies demonstrated the safety and potential benefit of autologous bone marrow cells in improving left ventricular function after acute myocardial infarction (AMI). However, a fundamental problem in developing stem cell (SC)–based therapies has been the