X-ray streaked refraction enhanced radiography for inferring inflight density gradients in ICF capsule implosions

In the quest for reaching ignition of deuterium-tritium (DT) fuel capsule implosions, experiments on the National Ignition Facility (NIF) have shown lower final fuel areal densities than simulated. Possible explanations for reduced compression are higher preheat that can increase the ablator-DT ice density jump and induce mix at that interface or reverberating shocks. We are hence developing x-ray Refraction Enhanced Radiography (RER) to infer the inflight density profiles in layered fuel capsule implosions. We use a 5 μm slit backlit by a Ni 7.8 keV He-α NIF laser driven x-ray source positioned at 20 mm from the capsule to cast refracted images of the inflight capsule onto a streak camera in a high magnification (M ∼ 60×) setup. Our first experiments have validated our setup that recorded a streaked x-ray fringe pattern from an undriven high density carbon (HDC) capsule consistent with ray tracing calculations at the required ∼6 μm and 25 ps resolution. Streaked RER was then applied to inflight layered HDC capsule implosions using a hydrogen-tritium fuel mix rather than DT to reduce neutron yields and associated backgrounds. The first RER of an imploding capsule revealed strong features associated with the ablation front and ice-ablator interface that are not visible in standard absorption radiographs.

Development of a spectroscopic technique for simultaneous magnetic field, electron density, and temperature measurements in ICF-relevant plasmas

Spectroscopic techniques in the visible range are often used in plasma experiments to measure B-field induced Zeeman splitting, electron densities via Stark broadening, and temperatures from Doppler broadening. However, when electron densities and temperatures are sufficiently high, the broadening of the Stark and Doppler components can dominate the emission spectra and obscure the Zeeman component. In this research, we are developing a time-resolved multi-axial technique for measuring the Zeeman, Stark, and Doppler broadened line emission of dense magnetized plasmas for Z-pinch and Dense Plasma Focus (DPF) accelerators. The line emission is used to calculate the electron densities, temperatures, and B-fields. In parallel, we are developing a line-shape modeling code that incorporates the broadening effects due to Stark, Doppler, and Zeeman effects for dense magnetized plasma. This manuscript presents the details of the experimental setup and line shape code, along with the results obtained from an Al iii doublet at the University of Nevada, Reno at Nevada Terawatt Facility. Future tests are planned to further evaluate the technique and modeling on other material wire array, gas puff, and DPF platforms.

Structured photocathodes for improved high-energy x-ray efficiency in streak cameras

We have designed and fabricated a structured streak camera photocathode to provide enhanced efficiency for high energy X-rays (1-12 keV). This gold coated photocathode was tested in a streak camera and compared side by side against a conventional flat thin film photocathode. Results show that the measured electron yield enhancement at energies ranging from 1 to 10 keV scales well with predictions, and that the total enhancement can be more than 3×. The spatial resolution of the streak camera does not show degradation in the structured region. We predict that the temporal resolution of the detector will also not be affected as it is currently dominated by the slit width. This demonstration with Au motivates exploration of comparable enhancements with CsI and may revolutionize X-ray streak camera photocathode design.

A multi-wavelength, high-contrast contact radiography system for the study of low-density aerogel foams

A multi-wavelength, high contrast contact radiography system has been developed to characterize density variations in ultra-low density aerogel foams. These foams are used to generate a ramped pressure drive in materials strength experiments at the National Ignition Facility and require precision characterization in order to reduce errors in measurements. The system was used to characterize density variations in carbon and silicon based aerogels to ∼10.3% accuracy with ∼30 μm spatial resolution. The system description, performance, and measurement results collected using a 17.8 mg/cc carbon based JX-6 (C20H30) aerogel are discussed in this manuscript.

Measuring the diffraction properties of an imaging quartz(211) crystal

A dual goniometer X-ray system was used to measure the reflectivity curve for a spherically bent quartz(211) crystal. An analysis of the dual goniometer instrument response function for the rocking curve width measurement was developed and tested against the actual measurements. The rocking curve was measured at 4510.8 eV using the Ti Kα1 characteristic spectral line. The crystal is the dispersion element for a high resolution spectrometer used for plasma studies. It was expected to have a very narrow rocking curve width. The analysis showed that we could measure the upper bound for the rocking curve width of the Qz(211) crystal. The upper bound was 58 μrad giving a lower bound for the instrument resolving power E/ΔE = 34 000. Greatly improved insight into the dual goniometer operation and its limitations was achieved.

High Miller-index germanium crystals for high-energy x-ray imaging applications

Near-normal-incidence bent crystals are widely used for x-ray imaging applications. Advantages include high collection solid angle and potentially high efficiency for narrow-band sources, while disadvantages include relatively large (several Å) interatomic spacings and a limited number of suitable matches between a crystal 2d value and an integral multiple of useful emission line wavelengths. The disadvantages become more significant at x-ray energies >10  keV. The former disadvantage can be mitigated by using high-order reflections from crystal planes having low Miller indices, but both disadvantages can be mitigated by using low-order reflections from crystal planes having high Miller indices. We report here on integrated reflectivity measurements we performed of Ge (15,7,7) (2d=0.6296  Å), a candidate for imaging Ru He-α (θ(B)=87°). We find good agreement with calculations, and the data show a multitude of closely spaced reflections with slightly different Bragg angles including a fifth-order reflection of Ge (3,1,1) that has comparable reflectivity. This demonstrates that arbitrary choices of Miller indices in Ge crystals can be used to fine-tune Bragg angles for near-normal-incidence x-ray imaging at tens of kiloelectron volt x-ray energies with minimal lower-energy contamination from lower-order reflections, and that existing calculational tools can be used to reliably estimate integrated reflectivity.

High quantum efficiency photocathode simulation for the investigation of novel structured designs

A computer model in CST Studio Suite has been developed to evaluate several novel geometrically enhanced photocathode designs. This work was aimed at identifying a structure that would increase the total electron yield by a factor of two or greater in the 1-30 keV range. The modeling software was used to simulate the electric field and generate particle tracking for several potential structures. The final photocathode structure has been tailored to meet a set of detector performance requirements, namely, a spatial resolution of <40 μm and a temporal spread of 1-10 ps. We present the details of the geometrically enhanced photocathode model and resulting static field and electron emission characteristics.

Simple solution to the Fresnel-Kirchoff diffraction integral for application to refraction-enhanced radiography

We present a simple solution to the Fresnel-Kirchoff diffraction integral that is appropriate for x-ray radiography of strongly absorbing and phase-shifting objects in the geometrical optics regime, where phase contrast enhancements can be considered to be caused by refraction by a semi-opaque object. We demonstrate its accuracy by comparison to brute-force numerical ray trace and diffraction calculations of a representative simulated object, and show excellent agreement for spatial scales corresponding to Fresnel numbers greater than unity. The result represents a significant improvement over approximate formulas typically used in analysis of refraction-enhanced radiographs, particularly for radiography of transient phenomena in objects that strongly refract and show significant absorption.

High-resolution spectroscopy for Doppler-broadening ion temperature measurements of implosions at the National Ignition Facility

Future implosion experiments at the national ignition facility (NIF) will endeavor to simultaneously measure electron and ion temperatures with temporal and spatial resolution in order to explore non-equilibrium temperature distributions and their relaxation toward equilibrium. In anticipation of these experiments, and with understanding of the constraints of the NIF facility environment, we have explored the use of Doppler broadening of mid-Z dopant emission lines, such as krypton He-α at 13 keV, as a diagnostic of time- and potentially space-resolved ion temperature. We have investigated a number of options analytically and with numerical raytracing, and we have identified several promising candidate spectrometer designs that meet the expected requirements of spectral and temporal resolution and data signal-to-noise ratio for gas-filled exploding pusher implosions, while providing maximum flexibility for use on a variety of experiments that potentially include burning plasma.

Comparisons of NIF convergent ablation simulations with radiograph data

A technique for comparing simulation results directly with radiograph data from backlit capsule implosion experiments will be discussed. Forward Abel transforms are applied to the kappa*rho profiles of the simulation. These provide the transmission ratio (optical depth) profiles of the simulation. Gaussian and top hat blurs are applied to the simulated transmission ratio profiles in order to account for the motion blurring and imaging slit resolution of the experimental measurement. Comparisons between the simulated transmission ratios and the radiograph data lineouts are iterated until a reasonable backlighter profile is obtained. This backlighter profile is combined with the blurred, simulated transmission ratios to obtain simulated intensity profiles that can be directly compared with the radiograph data. Examples will be shown from recent convergent ablation (backlit implosion) experiments at the NIF.

Experimental study of neutron induced background noise on gated x-ray framing cameras

A temporally gated x-ray framing camera based on a proximity focus microchannel plate is one of the most important diagnostic tools of inertial confinement fusion experiments. However, fusion neutrons produced in imploded capsules interact with structures surrounding the camera and produce background to x-ray signals. To understand the mechanisms of this neutron induced background, we tested several gated x-ray cameras in the presence of 14 MeV neutrons produced at the Omega laser facility. Differences between background levels observed with photographic film readout and charge-coupled-device readout have been studied.

Pulse-dilation enhanced gated optical imager with 5 ps resolution (invited)

A 5 ps gated framing camera was demonstrated using the pulse-dilation of a drifting electron signal. The pulse-dilation is achieved by accelerating a photoelectron derived information pulse with a time varying potential [R. D. Prosser, J. Phys. E 9, 57 (1976)]. The temporal dependence of the accelerating potential causes a birth time dependent axial velocity dispersion that spreads the pulse as it transits a drift region. The expanded pulse is then imaged with a conventional gated microchannel plate based framing camera and the effective gating time of the combined instrument is reduced over that of the framing camera alone. In the drift region, electron image defocusing in the transverse or image plane is prevented with a large axial magnetic field. Details of the unique issues associated with rf excited photocathodes were investigated numerically and a prototype instrument based on this principle was recently constructed. Temporal resolution of the instrument was measured with a frequency tripled femtosecond laser operating at 266 nm. The system demonstrated 20× temporal magnification and the results are presented here. X-ray image formation strategies and photometric calculations for inertial confinement fusion implosion experiments are also examined.

Comparison of genetic-algorithm and emissivity-ratio analyses of image data from OMEGA implosion cores

Detailed analysis of x-ray narrow-band images from argon-doped deuterium-filled inertial confinement fusion implosion experiments yields information about the temperature spatial structure in the core at the collapse of the implosion. We discuss the analysis of direct-drive implosion experiments at OMEGA, in which multiple narrow-band images were recorded with a multimonochromatic x-ray imaging instrument. The temperature spatial structure is investigated by using the sensitivity of the Ly beta/He beta line emissivity ratio to the temperature. Three analysis methods that consider the argon He beta and Ly beta image data are discussed and the results compared. The methods are based on a ratio of image intensities, ratio of Abel-inverted emissivities, and a search and reconstruction technique driven by a Pareto genetic algorithm.

Using x-rays to test chemical vapor deposited diamond detectors for areal density measurement at the National Ignition Facility

At the National Ignition Facility (NIF), 192 laser beams will compress a target containing a mixture of deuterium and tritium that will release fusion neutrons, photons, and other radiation. Diagnostics are being designed to measure this emitted radiation to infer crucial parameters of an ignition shot. Chemical vapor deposited (CVD) diamond is one of the ignition diagnostics that will be used as a neutron time-of-flight detector for measuring primary (14.1 MeV) neutron yield, ion temperature, and plasma areal density. This last quantity is the subject of this study and is inferred from the number of downscattered neutrons arriving late in time, divided by the number of primary neutrons. We determine in this study the accuracy with which this detector can measure areal density when the limiting factor is detector and electronics saturation. We used laser-produced x-rays to reproduce NIF signals in terms of charge carrier density, time between pulses, and amplitude contrast and found that the effect of the large pulse on the small pulse is at most 8.4%, which is less than the NIF accuracy requirement of +/-10%.

Development of backlighting sources for a Compton radiography diagnostic of inertial confinement fusion targets (invited)

We present scaled demonstrations of backlighter sources, emitting bremsstrahlung x rays with photon energies above 75 keV, that we will use to record x-ray Compton radiographic snapshots of cold dense DT fuel in inertial confinement fusion implosions at the National Ignition Facility (NIF). In experiments performed at the Titan laser facility at Lawrence Livermore National Laboratory, we measured the source size and the bremsstrahlung spectrum as a function of laser intensity and pulse length from solid targets irradiated at 2x10(17)-5x10(18) W/cm(2) using 2-40 ps pulses. Using Au planar foils we achieved source sizes down to 5.5 microm and conversion efficiencies of about 1x10(-13) J/J into x-ray photons with energies in the 75-100 keV spectral range. We can now use these results to design NIF backlighter targets and shielding and to predict Compton radiography performance as a function of the NIF implosion yield and associated background.

Spectroscopic determination of temperature and density spatial profiles and mix in indirect-drive implosion cores

In the field of inertial confinement fusion (ICF), work has been consistently progressing in the past decade toward a more fundamental understanding of the plasma conditions in ICF implosion cores. The research presented here represents a substantial evolution in the ability to diagnose plasma temperatures and densities, along with characteristics of mixing between fuel and shell materials. Mixing is a vital property to study and quantify, since it can significantly affect implosion quality. We employ a number of new spectroscopic techniques that allow us to probe these important quantities. The first technique developed is an emissivity analysis, which uses the emissivity ratio of the optically thin Lybeta and Hebeta lines to spectroscopically extract temperature profiles, followed by the solution of emissivity equations to infer density profiles. The second technique, an intensity analysis, models the radiation transport through the implosion core. The nature of the intensity analysis allows us to use an optically thick line, the Lyalpha, to extract information on mixing near the core edge. With this work, it is now possible to extract directly from experimental data not only detailed temperature and density maps of the core, but also spatial mixing profiles.

Imaging characteristics of hepatocellular carcinoma using the hepatobiliary contrast agent Gd-EOB-DTPA

PURPOSE

To evaluate the ability of contrast-enhanced magnetic resonance imaging (MRI) with Gd-EOB-DTPA in comparison with non-enhanced imaging and spiral computed tomography (CT) to provide additional information for classification and characterization of hepatocellular carcinoma.

MATERIAL AND METHODS

Forty patients with histopathology-proven hepatocellular carcinoma were selected for this subgroup analysis from a phase-III multicenter study in 235 patients with known or suspected liver lesions. The primary analysis was comparison of the proportion of hepatocellular carcinoma correctly classified and characterized by combined pre-/post-contrast MRI compared with pre-contrast MRI alone or with spiral CT. All images were evaluated on site, and in a blinded reading by three independent readers off site.

RESULTS

In the on-site evaluation, the lesions were correctly classified as a malignant tumor with combined MRI in 90.3%, with pre-contrast imaging alone in 82.9% and with spiral CT in 87.8% (n.s.). The proportion of correct characterization (lesion type diagnosis) with combined MRI was 85.4%, 75.6% for pre-contrast imaging, and 77.5% for spiral CT (n.s.), respectively. In the blinded reading, one reader showed a significant increase in the proportion of correctly characterized lesions by 27% (P<0.05). The other two readers showed a reduction in the proportion of correct characterization by 12% and 15%, respectively (n.s.).

CONCLUSION

With regard to lesion classification, no difference was found between combined pre-/post-contrast MRI and spiral CT. A non-significant trend in favor of Gd-EOB-DTPA-enhanced MRI with regard to characterization of hepatocellular carcinoma was found, although the CT scans were not optimized as the MRI scans.

Dopant radiative cooling effects in indirect-drive Ar-doped capsule implosion experiments

We present results from simulations performed to investigate the effects of dopant radiative cooling in inertial confinement fusion indirect-drive capsule implosion experiments. Using a one-dimensional radiation-hydrodynamics code that includes inline collisional-radiative modeling, we compute in detail the non-local thermodynamic equilibrium atomic kinetics and spectral characteristics for Ar-doped DD fuel. Specifically, we present results from a series of calculations in which the concentration of the Ar is varied, and examine the sensitivity of the fuel conditions (e.g., electron temperature) and neutron yield to the Ar dopant concentration. Simulation results are compared with data obtained in OMEGA indirect-drive experiments in which monochromatic imaging and spectral measurements of Ar Hebeta and Lybeta line emission were recorded. The incident radiation drive on the capsule is computed with a three-dimensional view factor code using the laser beam pointings and powers from the OMEGA experiments. We also examine the sensitivity of the calculated compressed core electron temperatures and neutron yields to the radiation drive on the capsule and to the radiation and atomic modeling in the simulations.

K(alpha) fluorescence measurement of relativistic electron transport in the context of fast ignition

Electron transport within solid targets, irradiated by a high-intensity short-pulse laser, has been measured by imaging K(alpha) radiation from high- Z layers (Cu, Ti) buried in low- Z (CH, Al) foils. Although the laser spot is approximately 10 microm [full width at half maximum (FWHM)], the electron beam spreads to > or =70 microm FWHM within <20 microm of penetration into an Al target then, at depths >100 microm, diverges with a 40 degree spreading angle. Monte Carlo and analytic models are compared to our data. We find that a Monte Carlo model with a heuristic model for the electron injection gives a reasonable fit with our data.

Carboplatin in Combination with Bendamustine in Previously Untreated Patients with Extensive-Stage Small Cell Lung Cancer (SCLC)

BACKGROUND AND OBJECTIVE

Bendamustine is an alkylating agent with high efficacy in non-Hodgkin's lymphoma and multiple myeloma. Even in solid tumours, monotherapy with bendamustine has resulted in subjective remissions and has been associated with a low rate of side effects. The current dose-finding study was designed to determine the maximum tolerated dose (MTD) of combined carboplatin/bendamustine in previously untreated patients with extensive-stage small cell lung cancer (SCLC).

PATIENTS AND METHODS

Carboplatin was administered as a 1-hour infusion on day 1 at increasing dose levels, and bendamustine was administered as a short infusion on days 1 and 2 at increasing dose levels (80-120 mg/m(2)). The regimen was administered every 3 weeks. Four dose levels were planned, starting with 80 mg/m(2) bendamustine and carboplatin area under the curve (AUC) 5 (dose level I). The other dose levels were 100 mg/m(2) bendamustine and carboplatin AUC 5 (dose level II), 100 mg/m(2) bendamustine and carboplatin AUC 6 (dose level III), and 120 mg/m(2) bendamustine and carboplatin AUC 6 (dose level IV). A minimum of three patients were enrolled at each dose level.

RESULTS

Dose-limiting toxicities, which included fatigue, infection and tachyarrhythmia, were observed at dose level III. The recommended dose for phase II studies was therefore established at dose level II. The majority of haematological and non-haematological toxicities observed were only mild (grade 1 or 2) in patients at dose levels I and II. None of the patients developed severe alopecia. Objective responses were observed in eight of the ten patients involved in this trial.

CONCLUSION

Because of its acceptable toxicity and favourable preliminary antitumour efficacy, the combination of carboplatin and bendamustine appears to be a potentially useful chemotherapeutic option in patients with extensive SCLC.

Experimental measurements of deep directional columnar heating by laser-generated relativistic electrons at near-solid density

In our experiments, we irradiated solid CH targets with a 400 J, 5 ps, 3 x 10(19) W/cm(2) laser, and we used x-ray imaging and spectroscopic diagnostics to monitor the keV x-ray emission from thin Al or Au tracer layers buried within the targets. The experiments were designed to quantify the spatial distribution of the thermal electron temperature and density as a function of buried layer depth; these data provide insights into the behavior of relativistic electron currents which flow within the solid target and are directly and indirectly responsible for the heating. We measured approximately 200-350 eV temperatures and near-solid densities at depths ranging from 5 to 100 microm beneath the target surface. Time-resolved x-ray spectra from Al tracers indicate that the tracers emit thermal x rays and cool slowly compared to the time scale of the laser pulse. Most intriguingly, we consistently observe annular x-ray images in all buried tracer-layer experiments, and these data show that the temperature distribution is columnar, with enhanced heating along the edges of the column. The ring diameters are much greater than the laser focal spot diameter and do not vary significantly with the depth of the tracer layer for depths greater than 30 microm. The local temperatures are 200-350 eV for all tracer depths. We discuss recent simulations of the evolution of electron currents deep within solid targets irradiated by ultra-high-intensity lasers, and we discuss how modeling and analytical results suggest that the annular patterns we observe may be related to locally strong growth of the Weibel instability. We also suggest avenues for future research in order to further illuminate the complex physics of relativistic electron transport and energy deposition inside ultra-high-intensity laser-irradiated solid targets.

Proton MR spectroscopy of the lumbar spine in patients with glycogen storage disease type Ib

Glycogen storage disease type Ib is an autosomal recessive inherited metabolic disorder resulting from deficiency of the microsomal glucose-6-phosphatase enzyme system. Six patients (three of which were treated with granulocyte colony stimulating factor) suffering from this disease were examined using image guided localized proton magnetic resonance (MR) spectroscopy. The relative signal intensities of water and lipid protons of the lumbar spine were determined. Comparison was made with iliac crest biopsies in the glycogen storage disease type Ib patients and localized proton MR spectroscopic values of the lumbar spine obtained by thirteen healthy volunteers. The data demonstrate for the first time that hypercellularity and myeloid hyperplasia in subjects with glycogen storage disease type Ib due to functionally impaired leucocytes results in a strongly increased water proton signal with a very low or absent lipid signal in localized proton MR spectroscopy. Upon granulocyte colony stimulating factor treatment, the water proton signal in the lumbar spine is not further augmented.

[Lipoid pneumonia following attempted suicide by intravenous injection of lamp oil]

BACKGROUND

Pneumonic complications after intoxication with mineral oils have been described before in the contents of accidental aspiration and oral ingestion. However, intoxication following an intravenous injection leading to a lipoid pneumonia after an attempted suicide is a rare finding.

CASE REPORT

A case report is presented of an attempted suicide by intravenously self-injection of 20 ml lamp oil (liquid paraffin). Immediately after injection the patient suffered from dry coughing which changed in the course of the next hours into a productive cough with white thick mucous sputum accompanied by hemoptysis. Additionally, he developed a mild disseminated intravascular coagulation with a fall of thrombocytes, an INR of 1.6 and a rise of D-dimeres. Under a therapy with hydrocortisone, ascorbic acid, ambroxol, acetylcysteine, heparin, antibiotics and oxygen, the patient improved without the need of mechanical ventilation. Initially seen signs of right heart dilatation diminished 3 days after onset of therapy. Apart from pulmonal manifestation no relevant organ damage was observed. The patient was discharged from the intensive care unit 9 days after intoxication and was submitted to psychiatric therapy.

CONCLUSION

Lipoid pneumonia caused by intoxication with a mineral oil is a severe disease, whereas in the presented case a relative bland course of the disease has been seen. The employed therapy in this patient might be encouraging for a comparable treatment of pneumological complications resulting from similar clinical pictures.

[Gaucher disease: MR evaluation of bone marrow features during treatment with enzyme replacement]

PURPOSE

Enzyme replacement therapy (ERT) arrests and reverses the hematological and visceral symptoms of adult Gaucher disease, the most frequent lysosomal storage disorder. There are only a few studies available evaluating bone disease during ERT. The aim of this study was to investigate the features of bone marrow (bm) by magnetic resonance imaging (MRI) in these patients during ERT.

MATERIALS AND METHODS

MRI was performed prospectively in thirty adult type I Gaucher patients before and during ERT with a mean follow-up of 3 years. Spin-echo sequences (T(1)/T(2)) of the lower extremities were obtained and the reconversion (response) or lack of reconversion (non-response) to fatty marrow during treatment was analyzed. The morphological features of bm involvement, a homogeneous or non-homogeneous distribution of bm changes and focal bone lesions surrounded by a rim of reduced signal intensity (SI), were analyzed.

RESULTS

Infiltration of bm by Gaucher cells is characterized by a reduction of SI on both T(1)- and T(2)-weighted sequences. Bone marrow responses were seen in 19 patients (63 %) during treatment. Focal bone lesions, surrounded by a rim of reduced SI, did not respond to ERT and correlated with a non-homogenous distribution of bone involvement and splenectomy.

CONCLUSION

In adult patients with type I Gaucher disease receiving ERT, treatment effects on bone disease can be demonstrated by MRI using Spin-echo sequences due to the partial reconversion of fat marrow. A non-homogeneous type of signal appearance and a status post splenectomy correlate with the presence of bone infarcts.

Magnetic resonance imaging of bone marrow changes in Gaucher disease during enzyme replacement therapy: first German long-term results

OBJECTIVE

Since 1991, enzyme replacement therapy (ERT) has been available for patients with Gaucher disease in Germany. The aim of this study was to analyse the MR pattern of bone marrow involvement and response to ERT in Gaucher disease type I.

PATIENTS AND DESIGN

Thirty patients with Gaucher disease type I had MRI examinations prior to initiation of ERT with alglucerase/imiglucerase and during follow-up. Median MR follow-up and duration of ERT were 36 months. Coronal T1- and T2-weighted spin-echo images of the lower extremities were obtained to evaluate changes in the appearance of yellow marrow. MR images were categorized as having either a homogeneous (type A) or non-homogeneous patchy (type B) appearance of bone involvement and response to ERT was assessed by two radiologists.

RESULTS

Overall, 19 of 30 patients (63%) showed an increased signal intensity on T1- and T2-weighted images after 36 months of ERT, consistent with partial reconversion of fatty marrow during treatment. Focal bone lesions surrounded by a low signal intensity (SI) rim did not respond to ERT, suggesting bone infarcts. Of the 11 patients with bone infarcts (low SI rim lesion), 82% had the non-homogeneous type B pattern (P=0.0021). In 86% of patients with splenectomy, bone infarcts were seen (P<0.05).

CONCLUSIONS

MRI using T1- and T2-weighted spin-echo sequences is a valuable, non-invasive method for monitoring bone marrow response in patients receiving ERT. A non-homogeneous patchy signal intensity of bone marrow involvement correlates with the presence of bone infarcts (P=0.0021).

HRCT findings of amiodarone pulmonary toxicity: clinical and radiologic regression

Amiodarone is an antiarrhythmic drug that can cause interstitial pneumonitis leading to pulmonary fibrosis. A 62-year-old man suffering from atrial fibrillation and recurrent dyspnea was treated with amiodarone. After 15 months of treatment, HRCT revealed bilateral interstitial and alveolar opacifications with high-attenuating pleural-parenchymal consolidations, suggesting amiodarone induced pneumonitis. Three months after cessation of amiodarone treatment, HRCT shows complete regression of pneumonitis. Amiodarone pneumonitis can be misinterpreted and mistreated in patients with further underlying diseases. The present case report demonstrates the diagnostic value of HRCT in the diagnosis of interstitial pneumonitis.

In vitro determination of cardiac ventricular volumes using MRI at 1.0 T in a porcine heart model

PURPOSE

To determine the accuracy of a 1.0 T MR system with a standard gradient system for quantification of left and right ventricular volumes. A porcine heart model in vitro was used.

METHODS

In eight explanted porcine hearts the atria were removed and the aorta and the pulmonary truncus were cannulated. Defined volumes were injected into the ventricles. Magnetic resonance imaging (MRI): FFE-EPI (Multishot EPI) was used. Papillary muscles and trabeculae were excluded. True volumes and MR measurements were analysed separately for both ventricles and by both investigators.

RESULTS

The correlation of the true volumes and MR measurements was >0.99. MRI was found to be investigator independent in assessing right and left ventricular volumes in vitro.

CONCLUSIONS

MRI at 1.0 T using standard equipment can be used to quantitate cardiac ventricular volumes in vitro with high accuracy.

Prevention of contrast media-induced renal dysfunction with prostaglandin E1: a randomized, double-blind, placebo-controlled study

Preexisting renal impairment is an all-encompassing risk factor for radiocontrast-associated nephrotoxicity. Renal impairment appears to be associated with the inadequate production of renal prostaglandins at the critical time of radiocontrast administration and for a variable time period afterward. We prospectively studied 130 patients with chronic renal insufficiency (serum creatinine > or =1.5 mg/dL) who were undergoing radiocontrast administration. Using a double-blind, randomized, prospective technique, patients were assigned to either placebo or one of three prostaglandin E1 (PGE1) treatment groups (10, 20, or 40 ng/kg/min). Infusion was started 60 +/- 30 minutes before the administration of radiocontrast and was continued for a total of 6 hours. In the placebo group, radiocontrast administration resulted in a mean increase (+/- SD) in serum creatinine of 0.72 +/- 1.15 mg/dL at 48 hours. This increase was less in each of the PGE1 treatment groups after 48 hours, with a significant difference between placebo and the 20 ng/kg/min PGE1 group (P = 0.01). Using baseline adjusted means, analysis of covariance with baseline serum creatinine as the covariable demonstrated significant differences between the placebo and 20 ng/kg/min PGE1 group (P = 0.03) and between the placebo and 10 ng/kg/min PGE1 group P = 0.047). In a subgroup analysis of the diabetic patients, the increase in serum creatinine was less pronounced in the three PGE1 groups versus the placebo group, and the 20 ng/kg/min PGE1 group had the most favorable outcome. The parenteral administration of PGE1 immediately before radiocontrast exposure and continued for a period of 5 to 5.5 hours significantly reduced the elevation of serum creatinine poststudy. The most effective of the three PGE1 dosing regimens was 20 ng/kg/min.

Extraosseous manifestation of Gaucher's disease type I: MR and histological appearance

Gaucher's disease type I is the most prevalent lysosomal storage disorder caused by an autosomal-recessive inherited deficiency of glucocerebrosidase activity with secondary accumulation of glucocerebrosides within the lysosomes of macrophages. The storage disorder produces a multisystem disease characterized by progressive visceral enlargement and gradual replacement of bone marrow with lipid-laden macrophages. Skeletal disease is a major source of disability in Gaucher's disease. Extraosseous extension of Gaucher cells is an extremely rare manifestation of skeletal Gaucher's disease. This is a report on the MRI and histopathological findings of an extraosseous Gaucher-cell extension into the midface in a patient with Gaucher's disease.

Long-term follow-up of left ventricular pacing via a posterior cardiac vein after mechanical tricuspid valve replacement

Permanent cardiac pacing was recommended in a 66-year-old woman with mechanical prosthetic mitral and tricuspid valves. To avoid a thoracotomy, a conventional endocardial lead was inserted with a steerable stylet (Locator) into the posterior cardiac vein via the right cephalic vein. Four weeks later, lead dislodgement required reoperation. The lead position remained stable up to 29 months.

Experimental comparison of a Shack-Hartmann sensor and a phase-shifting interferometer for large-optics metrology applications

We performed a direct side-by-side comparison of a Shack-Hartmann wave-front sensor and a phase-shifting interferometer for the purpose of characterizing large optics. An expansion telescope of our own design allowed us to measure the surface figure of a 400-mm-square mirror with both instruments simultaneously. The Shack-Hartmann sensor produced data that closely matched the interferometer data over spatial scales appropriate for the lenslet spacing, and much of the <20-nm rms systematic difference between the two measurements was due to diffraction artifacts that were present in the interferometer data but not in the Shack-Hartmann sensor data. The results suggest that Shack-Hartmann sensors could replace phase-shifting interferometers for many applications, with particular advantages for large-optic metrology.

Right and left ventricular volume measurements in an animal heart model in vitro: first experiences with cardiac MRI at 1.0 T

The aim of this study was to determine the accuracy in quantifying right and left ventricular volumes using a 1.0-T system and commercially available, standard equipment. For exact comparison of MRI measurements and real volumes we used an animal heart model ex vivo. Eight pig hearts were explanted and prepared by removal of the atria. Aorta and pulmonary truncus were cannulated. Definable volumes were injected into the ventricles. Magnetic resonance imaging was performed at 1.0 T (Gyroscan T10 NT, Philips, Eindhoven, The Netherlands); sequence: fast field echo-echo planar (multishot EPI); body coil; MR software: Cardiac Application Package (Philips). Statistical analysis correlated the real volumes and MR measurements separately for both ventricles and two investigators (SAS, ANOVA). For both ventricles and both investigators the correlation between real volumes and MR measurements was greater than 0.99. There was no significant systematic false estimation for both ventricles. Magnetic resonance imaging at 1.0 T using standard hardware and software equipment enables the quantification of right and left ventricular volumes with high approximation to the real volumes in vitro. There is a clear restriction in translating these data into a clinical application because under experimental conditions no motion-induced artifacts existed.

Gaucher disease of the spleen: CT and MR findings

We present a 26-year-old male patient with Gaucher disease who presented with epigastric pain and a palpable mass in the left abdomen. Ultrasound, abdominal computed tomography, and magnetic resonance imaging showed massive splenomegaly with multiple splenic nodules up to 7 cm in diameter. Splenic nodules should be included in the differential diagnosis of splenic masses. Follow-up is necessary because of the increased incidence of hematologic malignancies in Gaucher disease.

[Determining left and right ventricular volume ejection fractions (VEF) with MRI at 1.0 T. Comparison of manual and semi-automated endocardium detection]

PURPOSE

To evaluate method- and user effects as well as the required time in the determination of left- and right ventricular ejection fractions in comparing manual and semiautomatic border detection of the endocardium.

METHODS

In 22 patients with varying cardiac diseases endocardial borders were detected either manually or semi-automatically (seeded ROI) and subsequently the right and left ventricular volume ejection fractions were computer-calculated. Two investigators defined the endocardial borders for both ventricles using both methods. For statistical analysis two-factorial analyses of variance were performed for the four variables: VEF right ventricle, VEF left ventricle, required time right ventricle, required time left ventricle (SAS, Anova).

RESULTS

There was no user or method effect detectable for both ventricles. The required time for both ventricles also did not reveal a user effect, but there was a dramatic method effect concerning a reduction of the required time for analysis for both ventricles > 50%.

CONCLUSIONS

The semiautomatic mode for detecting the endocardial borders in determining right and left ventricular ejection fractions did not demonstrate results differing from the results of the manual method, but is significantly superior concerning the time required for analysing ejection fractions of both ventricles with a reduction of over 50%. This might significantly reduce the expenditure for personnel.

Prostaglandin E1: a new agent for the prevention of renal dysfunction in high risk patients caused by radiocontrast media? PGE1 Study Group

BACKGROUND

Acute renal failure following the administration of radiocontrast media (RCM) is a complication found especially in patients with impaired renal function. Within the limits of a pilot study, the objective was to (a) show the effectiveness and compatibility of prostaglandin E(1) (PGE(1)=Alprostadil) in preventing acute renal failure in patients with elevated levels of serum creatinine and (b) to identify the most appropriate PGE(1)-dose.

METHODS

130 patients with renal impairment (serum creatinine >/=1.5 mg/dl) were included in the study prior to intravascular RCM injection. The patients received one of three different doses of PGE(1) (10, 20, or 40 ng/kg bodyweight/min) or placebo (physiologic sodium chloride solution) intravenously over a time period of 6 h (beginning 1 h prior to RCM application). Serum creatinine was measured 12, 24, and 48 h post RCM-application and creatinine clearance was determined with two 12 h collection periods, as well as one 24 h collection within 48 h post RCM administration. Adverse events during PGE(1) administration were recorded.

RESULTS

In the placebo group, the mean elevation of serum creatinine was markedly higher (0.72 mg/dl) 48 h after RCM administration compared with the three PGE(1) groups (0.3 mg/dl in the 10 ng/kg/min group, 0. 12 mg in the 20 ng/kg/min group, and 0.29 mg/dl in the 40 ng/kg/min group). No clinically relevant changes were seen regarding the creatinine clearance in the four groups examined.

CONCLUSIONS

Results from this pilot-study suggest that intravenous PGE(1) may be used efficaciously and safely to prevent RCM-induced renal dysfunction in patients with pre-existing impaired renal function.

Type I gaucher disease: extraosseous extension of skeletal disease

OBJECTIVE

To investigate the frequency and morphology of extraosseous extension in patients with Gaucher disease type I.

DESIGN AND PATIENTS

MRI examinations of the lower extremities were analyzed in 70 patients with Gaucher disease type I. Additionally, the thoracic spine and the midface were investigated on MRI in two patients.

RESULTS

Four cases are presented in which patients with Gaucher disease type I and severe skeletal involvement developed destruction or protrusion of the cortex with extraosseous extension into soft tissues. In one patient, Gaucher cell deposits destroyed the cortex of the mandible and extended into the masseter muscle. In the second patient, multiple paravertebral masses with localized destruction of the cortex were apparent in the thoracic spine. In the third and fourth patient, cortical destruction with extraosseous tissue extending into soft tissues was seen in the lower limbs.

CONCLUSIONS

Extraosseous extension is a rare manifestation of Gaucher bone disease. While an increased risk of cancer, especially hematopoietic in origin, is known in patients with Gaucher disease, these extraosseous benign manifestations that may mimic malignant processes should be considered in the differential diagnosis of extraosseous extension into soft tissues. A narrow neck of tissue was apparent in all cases connecting bone and extraosseous extensions.