The 2014 primary health care reform in Poland: Short-term fixes instead of a long-term strategy.

At the end of 2013, the Minister of Health started legislative changes directly and indirectly affecting primary health care (PHC). The reforms were widely criticised among certain groups of medical professionals, including family medicine physicians. The latter mainly criticised the formal inclusion of specialists in internal diseases and paediatrics into PHC within the statutory health care system, which in practice meant that these two groups of specialists were no longer required to specialize in family medicine from 2017 in order to enter into contracts with the public payer and would be able to set up solo PHC practices-something over which family medicine physicians used to have a monopoly. They argued that paediatricians and internists did not have the necessary professional competencies to work as PHC physicians and thus assure provision of a comprehensive and coordinated PHC. The government's stance was that the proposed measure was necessary to assure the future provision of PHC, given the shortage of specialists in family medicine. Certain groups of medical professionals were also supportive of the proposed change. The key argument in favour was that it could improve access to PHC, especially for children. However, while this was not the subject of the critique or even a policy debate, the proposal ignored the increasing health care needs of older patients-the key recipients of PHC services. The policy was passed in the Parliament in March-April 2014 without a dialogue with the key stakeholders, which is typical of health care (and other) reforms in Poland. The strong opposition against the reform from the family medicine specialists, represented by two strong organisations, may jeopardise the policy implementation in the future.

Implementation of the cross-border healthcare directive in Poland: How not to encourage patients to seek care abroad?

In October 2014, after over 12 months of delay, Poland finally implemented directive 2011/24/EU on the application of patients' rights in cross-border healthcare. The implementing legislation in the area of cost reimbursement and prior authorization is very restrictive. The goal is to either defer the public payer's expenses into the future or to discourage patients from seeking care abroad or from seeking care altogether. The Polish government and the Ministry of Health, the key stakeholders in the implementation process, seemed to overlook the potential monetary benefits that the implementation of the directive could bring, for example, by promoting Poland as a destination for health tourism. Other stakeholders, such as patients and healthcare providers, had no real influence on the policy process. So far, the number of applications for planned treatment abroad has been very low and the majority of them were actually turned down as they did not meet the formal requirements. This number is likely to remain low in the future as accessing such care is cumbersome and not affordable for many patients. Overall, while the directive does not aim to encourage patients to seek cross-border healthcare, the current national regulations in Poland do not seem to facilitate access to cross-border healthcare, which is the main goal of the directive.

Comparison of MR-thermography and planning calculations in phantoms.

A systematic comparison of three-dimensional MR (magnetic resonance) thermography and planning calculations in phantoms for the hyperthermia (HT) SIGMA-Eye applicator. We performed 2 x 6 experiments in a homogeneous cylindrical and a heterogeneous elliptical phantom by adjusting 82 different patterns with different phase control inside an MR tomograph (Siemens Magnetom Symphony, 1.5 Tesla). For MR thermography, we employed the proton resonance frequency shift method with a drift correction based on silicon tubes. For the planning calculations, we used the finite-difference time-domain (FDTD) method and, in addition, modeled the antennas and the transforming network. We generated regions according to a segmentation of bones and tissue, and used an interpolation technique with a subgrid of 0.5 cm size at the interfaces. A Gauss-Newton solver has been developed to adapt phases and amplitudes. A qualitative agreement between the planning program and measurements was obtained, including a correct prediction of hot spot locations. The final deviation between planning and measurement is in the range of 2-3 W/kg, i.e., below 10%. Additional HT phase and amplitude adaptation, as well as position correction of the phantom in the SIGMA-Eye, further improve the results. HT phase corrections in the range of 30-40 degrees and HT amplitude corrections of +/- 20-30% are required for the best agreement. The deviation /MR-FDTD/, and the HT phase/amplitude corrections depend on the type of phantom, certain channel groups, pattern steering, and the positioning error. Appropriate agreement between three-dimensional specific absorption rate distributions measured by MR-thermography and planning calculations is achieved, if the correct position and adapted feed point parameters are considered. As long as feed-point parameters are uncertain (i.e., cannot be directly measured during therapy), a prospective planning will remain difficult. However, we can use the information of MR thermography to better predict the patterns in the future even without the knowledge of feed-point parameters.

Methods and potentials of magnetic resonance imaging for monitoring radiofrequency hyperthermia in a hybrid system.

INTRODUCTION: Non-invasive thermometry (NIT) is a valuable and probably indispensable tool for further development of radiofrequency (RF) hyperthermia. A hybridization of an MRI scanner with a hyperthermia system is necessary for a real-time NIT. The selection of the best thermographic method is difficult, because many parameters and attributes have to be considered. METHODS: In the hybrid system (Siemens Symphony/BSD-2000-3D) the standard methods for NIT were tested such as T1, diffusion (ADC: apparent diffusion coefficient) and proton-resonance-frequency shift (PFS) method. A series of three-dimensional datasets was acquired with different gradient-echo sequences, diffusion-weighted EPI spin-echo sequences and calculated MR-temperatures in the software platform AMIRA-HyperPlan. In particular for the PFS-method, corrective methods were developed and tested with respect to drift and other disturbances. Experiments were performed in phantoms and the results compared with direct temperature measurements. Then the procedures were transferred to clinical applications in patients with larger tumours of the lower extremity or the pelvis. RESULTS: Heating experiments and MR-thermography in a homogeneous cylindrical phantom give an excellent survey over the potentials of the methods. Under clinical conditions all these methods have difficulties due to motion, physiological changes, inhomogeneous composition and susceptibility variations in human tissues. The PFS-method is most stable in patients yielding reasonable MR temperature distributions and time curves for pelvic and lower extremity tumours over realistic treatment times of 60-90 min. Pooled data exist for rectal tumour recurrencies and soft tissue sarcomas. The fat tissue can be used for drift correction in these patients. T1 and diffusion-dependent methods appear less suitable for these patients. The standard methods have different sensitivities with respect to the various error sources. The advantages and pitfalls of every method are discussed with respect to the literature and illustrated by the phantom and patient measurements. CONCLUSIONS: MR-controlled RF hyperthermia in a hybrid system is well established in phantoms and already feasible for patients in the pelvic and lower extremity region. Under optimal conditions the temperature accuracy might be in the range of 0.5 degrees C. However a variety of developments, especially sequences and post-processing modules, are still required for the clinical routine.

[Part-body hyperthermia with a radiofrequency multiantenna applicator under online control in a 1.5 T MR-tomograph]. / Teilkörperhyperthermie mit einem Radiofrequenz-Multiantennen-Applikator unter online Kontrolle in einem 1.5 T MR-Tomographen.

Objective of this study is the integration of a multiantenna applicator for part-body hyperthermia (BSD 2000/3D) in a 1.5 T MR-tomograph (Siemens Magnetom Symphony) in order to perform noninvasive MR monitoring in real time to increase safety and effectiveness of heat treatments. The positioning unit is mechanically coupled to the MR gantry from the back side and the body coil is utilised for imaging. For that purpose, the hyperthermia antenna system (100 MHz, 1.500 W) and the MR receiver (63.9 MHs) have to be decoupled in terms of high frequency (filter) and electromagnetically (emc). The processing of MR data sets is performed in a hyperthermia planning system. A simultaneous operation of radiofrequency hyperthermia and MR system is possible at clinically relevant power levels. MR imaging is used for tumor-diagnostics (standard spin echo sequences), for hyperthermia planning (T1-weighted gradient echo sequences in equal- and opposed-phase techniques), and for temperature measurements according to the proton resonance frequency method (PRF method, phase evaluation registration using a gradient echo sequence with long echo time). In 33 patients with advanced pelvic and abdominal tumors we performed 150 heat sessions under MR monitoring. For 70% of these patients a visualisation of temperature sensitive data during treatment was possible. The evaluated difference images represent a superposition of real temperature -increase and a (temperature-induced) perfusion elevation. The -hybrid approach renders development of part body hyperthermia possible as an MR-controlled intervention in radiology.

Performance and use of current sheet antennae for RF-hyperthermia of a phantom monitored by 3 tesla MR-thermography.

Several MR-compatible current sheet antennae (CSA) of different height (h) (16 cm (l) x 8 cm (w) x 1-5 cm (h)) were built for simulated RF (96 MHz) hyperthermia of a medium-sized (12l) tissue-equivalent phantom inside a 3 tesla whole body tomograph. Prior to use, efficiencies of the CSA were determined by network analysis and by calorimetry. Depending on the height h of the CSA and on the thickness d(bolus) of the water bolus used for RF-coupling of the CSA to the lossy medium, their efficiency varied between 20-70% and the CSA with h = 3 cm was selected for simulated RF hyperthermia. During heating, spatial temperature distributions (20-42 degrees C) of five slices (voxel size 2 x 2 x 10mm(3)) were recorded intermittently within 4 s/slice by measuring the temperature dependent shift of the (1)H resonance frequency (125.32 MHz). A phased array consisting of two identical CSA produced distinctly different spatial temperature distributions at 0 and 180 degrees phase difference between both RF channels feeding the antennae. Within a one-dimensional heat diffusion model, the specific absorption rate (SAR) of the electromagnetic wave generated by a single antenna was deduced from the experimental data resulting in a penetration depth (1/e(2)) of approximately 4 cm.

Antenna arrays in the SIGMA-eye applicator: interactions and transforming networks.

OBJECTIVES: In multiantenna applicators such as the SIGMA-60 or SIGMA-Eye, which consist of 4 or 12 pairs of antennas shunt to 4 or 12 amplifiers ("antenna couplets"), phases and amplitudes in the feed points of these antennas under certain conditions can significantly differ from the values selected at the multichannel amplifier (forward parameters), mainly due to coupling. In the SIGMA-Eye, this interaction is particularly affected by the transforming networks between the generators and the feed points, thus hampering the control of the feed point parameters. In this work, we perform measurements at existing applicators, present a formalism to describe the facts numerically, and investigate modifications of the transforming networks to improve the performance. METHODS AND MATERIALS: We prepared an experimental setup for the SIGMA-Eye applicator that is fed by forward waves of a 12-channel amplifier system. In this setup, we made the water bolus, the interior of the tissue-equivalent phantom, and the entire transforming network accessible for measuring probes. Then, we constructed various alternative transforming networks such as Pawsey loops, LC matching networks, and power dividers and compared them with the original matching network of the SIGMA-Eye applicator. In particular, we utilized a high-resistive probe to determine the disturbances and influences caused by some channels with respect to some selected feed points of the SIGMA-Eye dipoles. RESULTS: In the original SIGMA-Eye applicator, the influences of coupling channels on the phases and voltages in the feed point of a particular antenna are largest for adjacent longitudinal channels. Here, the +/- 10 degrees phase shift and +/- 30% voltage change were observed if the reference channel (i.e., the disturbed channel) and disturbing channel are equally powered. The changes eminently increased to -30 degrees to + 100 degrees phase shift and -80% to +50% voltage change if the reference channel is fed with much lower power (four to eight-fold) than the disturbing channel. The disturbance from distant channels is less but still significant, reaching shifts of -10 degrees to +50 degrees and -50% to +20%, respectively. Using Pawsey loops instead of the original ferrite rings in the SIGMA-Eye network, the efficacy of the baluns was improved by a more than a factor of 4. Using an LC matching network, dependencies on frequency and external arrangements can be reduced significantly. Applying a power divider circuit, the coupling between antennas combined to one channel is considerably diminished (down to <-25 dB). CONCLUSION: Coupling between resonators (pairs of antennas including the matching network) reduces the control of the SIGMA-Eye applicator, i.e., it causes deviations between the selection of forward parameters at the amplifier and the total actual parameters in the feed points of the antennas. Modified transformation networks can improve the control, in particular by reducing sheath currents and asymmetries. There is a linear but variable relationship between selected (amplifiers) and actually given (feed points) parameters. This linear mapping (described by a matrix) and its characteristics need further investigation.

Histopathological correlation to MRI findings during and after laser-induced thermotherapy in a pig pancreas model.

RATIONALE AND OBJECTIVES: To investigate whether percutaneous laser-induced thermotherapy (LITT) with continuous magnetic resonance (MR) monitoring of thermal effects within the pancreas is feasible in a porcine model. METHODS: Laser applicators were placed in the pancreas of 15 female pigs. A temperature-sensitive (thermo--fast low-angle shot) sequence was used for continuous monitoring of thermal effects during LITT at 1.5 T. Follow-up MR images were acquired, the pigs were observed for 7 days, and then a pathological examination was performed after sacrifice. RESULTS: Continuous MR monitoring visualized thermal effects in pancreatic tissue and thermal damage of the spleen (n = 1), the left kidney (n = 1), and peripancreatic fat (n = 4) but missed the thermal damage of the duodenum (n = 2). Thermal-induced lesions (10--32-mm diameter) were clearly visualized on contrast-enhanced T1-weighted images. CONCLUSIONS: Laser-induced thermotherapy of pancreatic tissue was feasible in this porcine model, and online monitoring was practicable. Further studies are necessary to increase the accuracy of online MR imaging of thermal effects.

Electric field distributions in a phased-array applicator with 12 channels: measurements and numerical simulations.

In this paper we examine the SIGMA-Eye hyperthermia applicator (BSD Medical Corp., Salt Lake City, Utah 84119) with respect to the control of electric field distributions. This applicator is equipped with 12 pairs of antennas fed by 12 amplifiers, allowing the individual adjustment of phase and power for each of them. Measurements were conducted using phantoms with well-defined electrical properties. Specific electro-optical sensors, capable of measuring both electric field amplitudes and phases, have been developed, and a system for data acquisition and analysis has been set up. In its initial state the applicator appeared not to be satisfactorily matched at 100 MHz for the phantom used, with return losses up to 20% in power. By tuner readjustments we achieved values below 5%. For various settings of the amplifiers' control parameters we measured field distributions, both in the phantom and in the surrounding water bolus. The experimental results were compared with numerical simulations based on finite difference and finite element methods. Measured and calculated electric fields exhibit deviations of 10% on average, allowing, in principle, a satisfactory prediction of fields by numerical simulations or as well by on-line measurements at selected locations of the applicator at antenna proximity. However, to obtain this satisfactory agreement a modification of the control parameters in the calculations (phases and amplitudes in the feed points of the antennas) was necessary. The origin of these problems is mainly attributed to cross-talk phenomena and other characteristics of the transforming network, which need to be scrutinized further for a full understanding.

[Ability to work--new approach to evaluation methods]. / Zdolnosc do pracy--nowe podejscie do sposobu oceny.

In Poland, the assessment of work ability has thus far been almost entirely objective, which means that it was based on the evaluation of the individual's health state. That is why a subjective method of work ability assessment with work ability index (WAI), developed by the Occupational Health Institute in Helsinki, was used in our present study. This method allows to indicate other possible factors which modify work ability. The study covered 189 men employed in five metallurgical plants, located in the region of Lódz. In the study population, WAI and work load on the basis of the expenditure of energy were measured, the health condition was evaluated, and information on life styles and non-occupational responsibilities was gathered. It was found that WAI values were inversely proportional to age and work load. They were also modified by individual characteristics, such as life style, body mass, and activities at leisure. It was found that the correlation between the general index of work ability and the objective health indicators was low with the concomitant considerably higher correlation with the values of the components which reflect subjective work abilities. In view of the results obtained, WAI can be recommended as a tool for assessing work ability. Due to this method it is possible to present conclusively all elements of individual characteristics and to identify at the same time links with working conditions.

Is absolute noninvasive temperature measurement by the Pr[MOE-DO3A] complex feasible.

Recently, the feasibility of the praseodymium complex of 10-(2-methoxyethyl)-1,4,7,10-tetraaza-cyclododecane-1,4,7-tr iacetate (Pr[MOE-DO3A]) for non-invasive temperature measurement via 1H spectroscopy has been demonstrated. Particularly the suitability of the complex for non-invasive temperature measurements including in vivo spectroscopy without spatial resolution as well as first spectroscopic imaging measurements at low temporal resolution (> or = 4 min) and high temporal resolution (breath hold, approximately 20 s) has been shown. As of today, calibration curves according to the particular experimental conditions are necessary. This work aims to clarify whether the Pr[MOE-DO3A] probe in conjunction with 1H-NMR spectroscopy allows non-invasive absolute temperature measurements with high accuracy. The measurement results from two different representative media, distilled water and human plasma, show a slight but significant dependence of the calibration curves on the surrounding medium. Calibration curves in water and plasma were derived for the temperature dependence of the chemical shift difference (F) between Pr[MOE-DO3A]'s OCH3 and water with F = -(27.53 +/- 0.04) + (0.125 +/- 0.001) x T and F = -(27.61 +/- 0.02) + (0.129 +/- 0.001) x T, respectively, with F in ppm and T in degrees C. However, the differences are minuscule even for the highest spectral resolution of 0.001 ppm/pt, so that they are indistinguishable under practical conditions. The estimated temperature errors are +/- 0.18 degrees C for water and +/- 0.14 degrees C for plasma and with that only slightly worse than the measurement accuracy of the fiber-optical temperature probe (+/- 0.1 degrees C). It can be concluded that the results obtained indicate the feasibility of the 1H spectroscopy method in conjunction with the Pr[MOE-DO3A] probe for absolute temperature measurements, with a maximum accuracy of +/- 0.2 degrees C.

Comparison of four magnetic resonance methods for mapping small temperature changes.

Non-invasive detection of small temperature changes (< 1 degree C) is pivotal to the further advance of regional hyperthermia as a treatment modality for deep-seated tumours. Magnetic resonance (MR) thermography methods are considered to be a promising approach. Four methods exploiting temperature-dependent parameters were evaluated in phantom experiments. The investigated temperature indicators were spin-lattice relaxation time T1, diffusion coefficient D, shift of water proton resonance frequency (water PRF) and resonance frequency shift of the methoxy group of the praseodymium complex (Pr probe). The respective pulse sequences employed to detect temperature-dependent signal changes were the multiple readout single inversion recovery (T One by Multiple Read Out Pulses; TOMROP), the pulsed gradient spin echo (PGSE), the fast low-angle shot (FLASH) with phase difference reconstruction, and the classical chemical shift imaging (CSI). Applying these sequences, experiments were performed in two separate and consecutive steps. In the first step, calibration curves were recorded for all four methods. In the second step, applying these calibration data, maps of temperature changes were generated and verified. With the equal total acquisition time of approximately 4 min for all four methods, the uncertainties of temperature changes derived from the calibration curves were less than 1 degree C (Pr probe 0.11 degrees C, water PRF 0.22 degrees C, D 0.48 degrees C and T1 0.93 degrees C). The corresponding maps of temperature changes exhibited slightly higher errors but still in the range or less than 1 degree C (0.97 degrees C, 0.41 degrees C, 0.70 degrees C, 1.06 degrees C respectively). The calibration results indicate the Pr probe method to be most sensitive and accurate. However, this advantage could only be partially transferred to the thermographic maps because of the coarse 16 x 16 matrix of the classical CSI sequence. Therefore, at present the water PRF method appears to be most suitable for MR monitoring of small temperature changes during hyperthermia treatment.

Design and test of a new multi-amplifier system with phase and amplitude control.

The clinical relevance of the radiofrequency regional hyperthermia (RF-RHT) as an adjuvant cancer therapy grows continuously. Simulation studies for optimization of RF-RHT based on the annular phased array systems have shown a significant improvement of power deposition patterns with increasing number of channels. However, this probably requires higher phase accuracy and amplitude stability than are provided by presently used clinical systems, e.g. BSD-2000. Measurements performed on the BSD-200 electronic revealed phase inaccuracies up to +/- 20 degrees and errors in the power registration of +/- 20 W (up to +/- 50 W in the low power range). These errors are further enhanced by the mismatching of the external load (antenna applicator) and thermal instabilities. To achieve the required phase accuracy and long-term stability in the prototype of a new amplifier system, single-sideband (SSB) mixing in combination with direct digital synthesizers (DDS), in-phase and quadrature-phase (IQ) processing and phase-lock loop (PLL) were used. In the DDS's the actual phase of the output signal of each channel is calculated in real-time. No analogue control loop is involved that may cause thermal offset or drift problems. Each DDS operates at a low intermediate frequency (IF) of 1 MHz. To transform the phase information of this IF signal into the desired RF band, SSB mixing-up is performed. A second frequency source, operating as a local oscillator (LO) in the RF band, is required for this technique. Also, the frequency adjustment of the desired RF signal is performed in the LO. These phase and frequency adjustment units are followed by the high efficiency AB-class solid state amplifier unit. The phase and power level stability of the amplifier are controlled by means of digital PLL structures in conjunction with look-up tables. For this control test signals are coupled out by means of directional couplers. The phase control is based on very sensitive phase comparison. These digital control loops are programmable and allow the implementation of different control algorithms. The achieved long-term accuracy (95% confidence interval) is +/- 1-3 W for output power levels ranging from 10-100 W, and +/- 1 degree for phase differences between each channel and a reference signal at a constant power level, and +/- 1.5 degrees for phase difference values at variable power levels between 10-100 W. In conclusion, the new amplifier system is smaller and more efficient than presently available commercial systems.

Non-invasive MR thermometry by 2D spectroscopic imaging of the Pr[MOE-DO3A] complex.

Future progress in regional hyperthermia requires a practical method for non-invasive thermometry. In magnetic resonance tomography, spin density, T1 relaxation time, diffusion coefficient and proton resonance frequency are candidates to measure temperature distributions. When used clinically in the pelvic region, all these methods are compromized by artifacts arising from different tissues, tissue alterations under hyperthermia, physiological and random movements, inhomogeneities, drift phenomena, and field instabilities. In this study a paramagnetic complex was evaluated, Pr[MOE-DO3A], with praseodymium as central atom, similar to common gadolinium containing MRI contrast media. The temperature dependence of its methoxy side group approximately -24 ppm downfield from the water resonance at 25 degrees C was employed to determine 2-D temperature distributions in a cylindrical agar phantom containing 9.5 mM of Pr[MOE-DO3A]. The phantom was heated externally through a water jacket creating a stationary temperature distribution throughout the phantom. At first, the correlation between temperature and the chemical shift of the methyl group of the lanthanide complex Pr[MOE-DO3A] was determined. Calibration curves obtained exhibited a linear relationship of 0.12 +/- 0.01 ppm/degree C, nearly independent from the surrounding medium. Local temperature distributions were determined employing the spatially resolved method of spectroscopic imaging (SI). 2-D spectroscopic images for three orthogonal slices were obtained by narrow-band excitation and 16 phase encoding steps in two dimensions. The FOV was 180 mm and the slice thickness in all cases was 20 mm for maximal spatial temperature resolution (11.2 x 11.2 mm2). The results indicate a measurement time of about 5s per acquisition under the following conditions: An estimated concentration of 1 mmol/l, a reduced matrix size of 8 x 8, and a reduced repetition time of 3 x T1 (TR approximately 85 ms). Those SI measurements produced a SNR of approximately 4 per acquisition, a measurements duration of 10-20 s, equivalent to two to four acquisitions per spectrum, seem sufficient for online temperature monitoring during hyperthermia. The in vitro data suggest the spectroscopic temperature measurement utilizing a temperature-sensitive Pr[MOE-DO3A] complex with a therapeutically realistic concentration of 1 mmol/l to be suitable for clinical use. Compared to the methods tested so far (rho, T1, diffusion, proton resonance), the method presented has the unique advantage of being less susceptible to artifacts. The competing methods of non-invasive thermometry employing magnetic resonance imaging are currently being investigated using the same experimental setup.

Three-dimensional monitoring of small temperature changes for therapeutic hyperthermia using MR.

Radiofrequency hyperthermia of deep-seated pelvic tumors requires noninvasive monitoring of temperature distributions in patients. Methods of MR thermography were reported to be a promising tool in solving this problem. However, to be truly useful for monitoring hyperthermia treatments, MR thermography should be able to cover the entire pelvis in acquisition times no longer than for a breath-hold (< or = 15 seconds) and to resolve small temperature differences (< 1 degrees C). Three methods exploiting the temperature dependence of spin-lattice relaxation time (T1), of self-diffusion coefficient (D), and of chemical shift of proton resonance frequency (PRF) were applied in phantom experiments; the pulse sequences were the T1-weighted gradient echo, the pulsed diffusion gradient spin echo made faster through the keyhole technique, and the gradient echo with the phase reconstruction, respectively. The high planar resolution was compromised, and instead, coarse and more isotropic voxels were used. Experiments were performed in two consecutive steps, thus imitating a possible scenario for monitoring hyperthermia. In the first step, calibration curves were recorded, which were then used in the second step to obtain maps of temperature changes. The results show a clear superiority of the PRF method, followed by the D and the T1 methods. The uncertainty of temperature changes predicted both from calibration curves and from maps was less than 1 degrees C only with the PRF and the D-based methods.

Young Investigator Award presentation at the 13th annual meeting of the ESMRMB, September 1996, Prague. Quantification of pulmonary water compartments by magnetic resonance.

The purpose of this study was to quantify pulmonary water compartments of total, intravascular, and extravascular lung water in excised and perfused sheep lungs with the use of magnetic resonance imaging techniques. Total lung water was measured by proton density maps calculated from multi-spin-echo images. Intravascular lung water was evaluated by magnetic resonance angiography before and after injection of gadolinium diethylenetriamine penta-acetic acid polylysine, a macromolecular paramagnetic contrast agent. Intravascular lung water was calculated from signal intensity histogram changes comparing pre- and postcontrast angiograms. Extravascular water was calculated as the difference between total and intravascular lung water. Quantities of total and intravascular lung water measured by magnetic resonance techniques were compared to reference results obtained from wet/dry weight gravimetry and Evans blue dilution performed after imaging. Magnetic resonance and reference results correlated significantly (total lung water: r = 0.93, p < 0.001; intravascular lung water: r = 0.80, p < 0.001; extravascular lung water: r = 0.89, p < 0.001). Therefore, we conclude that quantitative magnetic resonance techniques are potentially useful for the clinical evaluation of pulmonary water compartments.

[Iron oxide contrast media improve the magnetic resonance imaging of the portal vein system--an animal experimental study]. / Eisenoxydkontrastmittel verbessern die kernspintomographische Darstellung des portalvenösen Systems--eine tierexperimentelle Untersuchung.

PURPOSE: The aim was to demonstrate that intravenous superparamagnetic iron oxide contrast agents improve the delineation of the portal venous system. MATERIAL AND METHODS: The portal venous system of 8 minipigs was demonstrated by a FLASH 2-D MRA-sequence. Scans were acquired before and after intravenous administration of 10 and 20 mumol/kg of a superparamagnetic iron oxide contrast agent (SHU 555 A). Signal intensities were measured in the portal vein and hepatic parenchyma and contrast-to-noise ratios were calculated. RESULTS: Following a cumulative dose of 10 mumol iron oxide, hepatic parenchymal signal intensity decreased to 67 +/- 6%, following 20 mumol to 29 +/- 4%, and following 40 mumol to 13 +/- 2% of control (p < 0.0001). These effects improved the contrast-to-noise ratio of the portal vein (469 +/- 114%, 858 +/- 243%, and 957 +/- 272% of control in the left portal vein main branch, p = 0.02). CONCLUSION: A decrease in hepatic parenchymal signal due to a magnetic susceptibility effect accounts for an improvement of portal venous conspicuity following intravenous administration of iron oxide contrast medium.

[Thermometry by measuring the chemical shift of lanthanide complex]. / Thermometrie durch Messung der chemischen Verschiebung eines Lanthanidenkomplexes.

BACKGROUND: In the long-term, non-invasive thermometry is vital for the continued clinical and technological development of regional hyperthermia. In magnetic resonance tomography. T1 relaxation time, diffusion and proton resonance frequency are used to measure temperature distributions. When used clinically in the pelvic region, all of these methods are plagued with errors and artefacts on account of the tissue relationships, tissue changes under hyperthermia, physiological and stochastic movements, inhomogeneities, drift phenomena and instabilities. MATERIAL AND METHOD: We tested the relationship between the temperature and the chemical shift of a methyl group of a lanthanide complex with central atom praseodymium (Pr-MOE-DO3A. Schering AG). To do this we used cylindrical phantoms containing a 5-mmol-solution of this temperature-sensitive substance. High resolution spectra and relaxation times were determined in a Bruker AMX at 11.5 T. A calibration curve was then recorded by a Siemens Magnetom SP63 at 1.5 T. Local temperature distributions were determined using the chemical shift imaging method, with a matrix size of 16 x 8 and a narrow-band excitation pulse. The temperature distribution was created using a Nd:YAG laser applicator. RESULTS: At a distance of -25.7 ppm from the water line, we found a singlet line with a temperature-dependent chemical shift of 0.13 ppm/C. In the phantom experiment we found that the chemical shift had a linear relationship with a gradient independent of the surroundings, and a temperature resolution of +/-0.6 degree C. With a concentration of 1 mmol/l, a matrix size of 8 x 8 and a measurement period of 5 s per acquisition, phantom measurements using the CSI method produced a signal to noise ratio of 3.5 per acquisition, i.e a measurement period of 10 to 20 s per spectrum. CONCLUSIONS: Our in vitro data show that spectroscopic temperature measurement using a temperature-sensitive praseodymium complex with a therapeutically practical concentration of 1 mmol/l already appears to be suitable for clinical use Compared with the methods tested so far (T1, diffusion, proton resonance), this method has the special advantage of not being very susceptible to artefacts. The competing methods of non-invasive thermometry using magnetic resonance tomography/spectroscopy will be investigated next.

Evaluation of portal MR angiography using superparamagnetic iron oxide.

The purpose of our research was to determine the effects of superparamagnetic iron oxide on MR imaging of the portal venous system. Eight piglets were examined in deep anaesthesia and respiratory arrest using a time-of-flight magnetic resonance fast low angle shot, two-dimensional angiography sequence at 1.5T, MR angiograms were acquired precontrast and after intravenous administration of a cumulative dose of 10, 20 and 40 mumol/kg SHU 555A, a superparamagnetic iron oxide contrast agent for MR imaging with a particle size of 60 nm. For each dose, two subsequent sets of scans were obtained and reconstructed by a maximum-intensity-projection algorithm. Hepatic parenchymal and portal venous signal intensities were measured, and portal vein contrast calculated for each set of scans. All examinations were visually rated as to portal vein contrast and homogeneity by two blinded observers. Receiver operating characteristics of both observers were analyzed. The contrast agent reduced hepatic parenchymal signal in a dose-dependent way. After a cumulative dose of 10 mumol iron oxide, hepatic parenchymal signal intensity decreased to 63 +/- 6% (average of measurements at 4 and 14 minutes, mean +/- standard error of the mean), after 20 mumol to 24 +/- 3%, and after 40 mumol to 12 +/- 1% of control. Intravascular signal in the left main portal vein branch increased to 117 +/- 6%, 127 +/- 10%, and 133 +/- 9% of control, respectively. The contrast-to-noise ratio of the portal vein improved (521 +/- 90%, 891 +/- 178%, and 995 +/- 201% of control in the left portal vein main branch). Intravascular signal intensities increased slightly. The combined effect improved contrast of the portal vein stem and its branches. Receiver operating characteristics analysis documented dose-dependency of contrast medium effects on portal venous contrast and intravascular homogeneity. Visual rating also indicated a positive effect on portal venous contrast. The superparamagnetic iron oxide agent improved portal venous contrast with surrounding hepatic parenchyma in this normal animal model, and could potentially result in more accurate diagnosis of portal venous pathology.