What is the best hydration regimen to prevent contrast media-induced nephrotoxicity?

BACKGROUND

Hydration is a commonly used method to prevent the decline in GFR after contrast media (CM) application. So far, there have been no controlled, randomized trials investigating the most effective route of fluid administration.

METHODS

Thirty-nine patients with normal renal function (65 +/- 9 years, serum creatinine 0.9 +/- 0.2 mg/dl, GFR = 110 +/- 31 ml/min/1.73 m2) receiving at least 80 ml of low-osmolality CM during an angiographic procedure were randomized to one of the following hydration regimens: Group 1: volume expansion with 300 ml saline during CM administration (n = 20, serum creatinine 0.8 +/- 0.1 mg/dl, GFR 119 +/- 27 ml/min/1.73 m2); Group 2: intravenous administration of at least 2,000 ml saline within 12 h before and after CM application (n = 19, serum creatinine 0.9 +/- 0.2 mg/dl, GFR 101 +/- 32 ml/min/1.73 m2). GFR was measured by CM clearance (Renalyzer) at baseline and 48 hours after CM administration. The primary end point was the mean change in the GFR after 48 hours, the secondary one was the incidence of CM-induced nephropathy (CMIN), defined as a decrease in GFR of more than 50% from the baseline GFR within 48 hours.

RESULTS

Patients of group 1 showed a significantly (p < 0.05) higher decline in GFR (delta GFR 34.6 +/- 25.7 ml/min/1.73 m2) compared to patients receiving the intravenous prehydration regimen (delta GFR 18.3 +/- 25.0 ml/min/1.73 m2). The incidence of CMIN was lower in prehydrated patients (5.3%) compared to the other group (15%).

CONCLUSION

In patients with normal renal function, intravenous prehydration seems to be a very effective and feasible method to prevent the decline in GFR after contrast media exposure. Volume expansion given only during the CM exposure appears not to be sufficient enough to prevent renal damage.

Uncommon case of a foreign body ingestion with consecutive small-bowel obstruction in a child

A 12-year-old boy with Lennox syndrome presented with an acute abdomen and a history of progressive abdominal pain and vomiting over 3 weeks. The uncommon finding in this case was a foreign body detected in a lower loop of the jejunum causing radiological and clinical signs of jejunitis/ileitis. The foreign body had to be removed surgically and turned out to be a hard (originally soft) plastic part of a towel rack.

Systematik der Artefakte metallischer Gefäßprothesen (Stents) in der MRT

PURPOSE

Imaging artifacts in magnetic resonance tomography (MRT) caused by metallic vascular implants (stents) were characterized systematically in dependence on the material and the construction of the implants as well as with respect to different measurement protocols and for different static field strength B (0).

METHODS

Twelve stents, different in material (stainless steel, nitinol, Co-alloy) and/or construction, were examined at B (0) = 0.2 T and 1.0 T with two 2D gradient echo (GE) sequences (TE = 4 and 10 ms), one 3D GE sequence and one spin echo (SE) sequence. The stents were put into water with Gd-DTPA contrast agent. The dependence on the orientation was analyzed for the 9 possibilities of an orthogonal alignment of the stent axis, the direction of B (0), the slice, the read out, and the phase encoding direction. Special interest was given to the visibility of the stent lumen at forced rf excitation, as well as to the influence of broken struts on the signal obtained.

RESULTS

For the examined stents GE technique showed, due to spin dephasing regions a total signal loss ranging up to 8 mm away from the stent mashes. The value depends on the stent material, the stent orientation in the scanner and grows with voxel size, echo time and B (0). In SE technique dephasing artifacts vanish and wrong spatial encoding gets visible, rf shielding is more pronounced. The visibility of the stent lumen ranges from nearly unperturbed down to a complete signal loss. An improvement is possible using enlarged flip angles. Broken struts can not be imaged significantly.

DISCUSSION

The MR representation of metallic stents commercially available at the time, especially of nitionol stents, can be optimized with a suitable adaptation of the imaging parameters. However, a profound improvement can only be expected from new stent material and design.

[Radiofrequency ablation ex vivo: comparison of the efficacy of impedance control mode versus manual control mode by using an internally cooled clustered electrode]

PURPOSE

To compare the effectiveness of pulsed (impedance control mode) and non-pulsed (manual control mode) radiofrequency ablation (RFA) by using an internal cooled-clustered electrode.

MATERIALS AND METHODS

Ex vivo RF ablations (n = 93) were performed with a 200 W RF generator (Model-Cooled Tip, Radionics, USA) in 10 bovine livers, using the impedance and manual control mode. In the impedance control mode, the generator automatically adjusted the applied RF power to the tissue impedance measured during RF ablation. In the manual control mode, the application of the RF power was constant. Both applications were investigated in a capacity range between 5 and 200 W. The duration for each RF ablation was between 2 and 60 minutes. After RF ablation, the short axis diameter of the necrosis was determined macroscopically and the peripheral zone of the necrosis histologically.

RESULTS

The impedance control mode produced lesions with short axis diameters of 5.3 +/- 0.3 cm at a power of 200 W after 60 minutes of RF ablation and the manual control mode lesions with short axis diameters of 4.1 +/- 0.4 cm at a power of 70 W after 8 +/- 2 minutes of RF ablation. The impedance control mode increased significantly the time of RF ablation with higher power and the size of necrosis (p < 0.01).

CONCLUSION

In comparison to non-pulsed RF ablation, pulsed RF ablation with internal cooled-clustered electrodes significantly increases the size of the lesions and represents a methodical optimization in our opinion.

Histological, growth and 7-ethoxyresorufin O-deethylase (EROD) activity responses of greenback flounder Rhombosolea tapirina to contaminated marine sediment and diet

Pathological abnormalities and mixed function oxygenase (MFO) enzyme changes are frequently used as indicators of anthropogenic contaminant exposure and effect. However, there is a paucity of research investigating the effects of contaminated sediment on native Australian benthic teleosts. As part of an ecotoxicological assessment of contaminated marine sediments in northern Tasmania, CYP1A induction, histological and growth response of the greenback flounder, Rhombosolea tapirina, exposed to contaminated marine sediments were examined. Hatchery reared flounder were exposed to reference sediment, contaminated sediment or contaminated sediment and diet for 6 weeks. CYP1A induction, using the ethoxyresorufin-O-deethylase (EROD) assay, and the histological and growth response in the flounder were examined on cessation of the exposure trial. Significant differences were found between treatments in histological, growth and EROD response. Exposure to contaminated sediment and diet elicited a multi-organ histological response: principally partial and total epidermal erosion and multifocal necrosis of the liver. The prevalence of total epidermal erosion was greatest with exposure to disturbed contaminated sediment (66.65+/-16.65%). The prevalence of multifocal necrosis of the liver was greatest with exposure to contaminated sediment and diet (66.65+/-16.65%). Growth reduction, measured as percentage growth inhibition, was evident in flounder exposed to contaminated sediment and diet (18.2+/-11.99%). Additionally, exposure to contaminated sediment and diet elicited elevated induction of the EROD liver detoxification enzyme (139.65+/-24.22 pmol/min/mg protein) compared to exposure to contaminated sediment and non-contaminated diet (6.25+/-0.81 pmol/min/mg) indicating the presence and potential bioavailability of xenobiotics via food. Further, more inhibited growth and histological alteration associated with exposure to contaminated sediment and diet suggest contaminants in Deceitful Cove sediment are cytotoxic.

MR imaging in the presence of vascular stents: A systematic assessment of artifacts for various stent orientations, sequence types, and field strengths

A systematic evaluation of the potential quality of magnetic resonance images recorded in the presence of metallic stents was performed on a low-field open imager operating at 0.2 T and on a high-field closed unit operating at 1.0 T. Eight different stent types were examined by two-dimensional gradient-echo sequences with echo times of 4 and 10 msec and by a fast spin-echo technique. In addition, a three-dimensional gradient-echo sequence was applied with an echo time of 2.4 msec. A set of sequence and slice parameters was used on both scanners. Thus, artifacts due to susceptibility effects depending on the magnetic field strength could be distinguished from radiofrequency shielding effects in the lumen of the stents (independent of the field strength). Nine different orthogonal orientations of the stent axis and the image (in terms of slice, read, and phase-encoding direction) were tested, and the artifacts (extension of signal void and visibility of the lumen) were compared. The optimal strategy for visualization of vascular and perivascular regions outside the stents was fast spin-echo imaging with the stent axis and read direction parallel to the static field. Susceptibility-induced signal void in gradient-echo images was minimal using the three-dimensional approach. Increased transmitter amplitudes above usual values provided clearly improved insight in the lumen using gradient-echo sequences.

Immune response of greenback flounder Rhombosolea tapirina after exposure to contaminated marine sediment and diet

Non-specific immune response of greenback flounder, Rhombosolea tapirina, exposed to contaminated marine sediments was examined. Reference sediments from Port Sorell and contaminated sediments from Deceitful Cove, Tasmania, Australia were investigated. Hatchery-reared flounder were exposed to reference sediment, contaminated sediment or contaminated sediment and diet for 6 weeks. Phagocytic capacity and lysozyme response in flounder were examined on cessation of exposure trial. Significant differences were found in phagocytic capacity and lysozyme response between treatments. Exposure to contaminated sediment, irrespective of diet or benthic disturbance elicited inhibition of phagocytic efficiency in flounder. Disturbance of contaminated sediment stimulated lysozyme activity. The immune response in flounder indicates potential immunotoxicity of sediment from Deceitful Cove.

Perspectives of coronary excimer laser angioplasty: multiplexing, saline flushing, and acoustic ablation control

BACKGROUND AND OBJECTIVE

Bubble formation, pressure wave generation, and cavitations constitute major factors influencing the outcome of clinical Excimer laser angioplasty. Thus, the rationale of this study was to determine the extent of pressure waves occurring during excimer laser ablation and to discuss possibilities that allow a less traumatic plaque removal in the coronary circulation.

STUDY DESIGN/MATERIALS AND METHODS

Conventional and experimental Xenon-Chlorid-Excimer lasers emitting light at a wave-length of 308 nm and a pulse duration of 115 ns were used for testing of signals. Whereas the conventional excimer laser light source transmits light through all fibers of a 1.7 mm laser catheter simultaneously, the prototype excimer laser divides the laser beam into several areas of uniform energy fluence by scanning the beam from one section to the other using the intermission between two laser discharges. Hydrophones consisting of piezoelectric films detected the acoustic signals, which were obtained on normal arterial wall and atherosclerotic plaque.

RESULTS

Multiplexing decreases maximum pressures for both normal arterial wall and calcified plaque significantly, whereas pressure rise time remains comparable. During ablation of pure blood, a linear increase of peak pressures of 1 MPa at 10 mJ/mm2 to 7.5 MPa at 50 mJ/mm2 is found. Contrast media intensifies the extent of pressure wave formation. At 20 mJ/mm2, 60% contrast media added to blood results in an increase of maximum pressures from 1.5 MPa up to 5 MPa. Dilution with saline solution is effective; however, high concentrations of > 90% are required to achieve a significant pressure wave reduction.

CONCLUSION

Peak pressures of several thousand kPa occur during excimer laser ablation of contrast media, blood, calcified plaque, and normal arterial wall in a decreasing order. Multiplexing and saline flushing are capable of reducing the intensity of the generated acoustic signals during tissue ablation. It has to be taken into consideration, however, that high concentrations of saline solution are necessary to achieve a significant reduction of peak pressures.

Raynaud-Phänomen als Leitsymptom bei Takayasu-Arteriitis

Die Takayasu-Arteriitis ist eine seltene entzündliche Erkrankung der Arterien. Neben allgemeinen Krankheitserscheinungen können durch Gefäßstenosierungen und -okklusionen vielfältige ischämische Symptome auftreten. Im vorliegenden Fall fungierte das einseitige Raynaudphänomen einer 34jährigen Patientin als Leitsymptom und führte zur klinischen und angiologischen Diagnosestellung. Einseitige Blutdruckerniedrigung rechts, verlängerte Pulswellenlaufzeit, poststenotische Doppler-Spektren der rechten A. brachialis sowie eine Flußumkehr der A. vertebralis wiesen auf eine Stenose im Bereich der A. subclavia hin. Duplexsonographisch und angiographisch wurden Stenosen der A. subclavia und des Truncus brachiocephalicus festgestellt. Nachdem zwischenzeitlich transitorische ischämische Attacken unter immunsuppressiver Therapie auftraten, wurde interdisziplinär die Indikation zu gefäßchirurgischem Vorgehen gestellt. Histologisch konnte die Diagnose Takayasu-Arteriitis bestätigt werden. Die Patientin wird klinisch und angiologisch interdisziplinär weiterbetreut.

[Pneumothorax in cigarette smokers]

From 1.01.1992 to 31.12.1998 ill prisoners were treated because of so called spontaneous pneumothorax. Their age was between 24 to 57, which was 33 in average. All of them were males and heavy smokers. In one case of the coat pneumothorax the treatment was limited only to the breathing exercises, to ten other patients an under-water-seal drainage was applied, in the next case with pneumothorax and clear symptoms of bronchial fistula, the lung expansion was obtained no sooner than after the usage of a suction drainage. The risk of recurrence of the illness was limited by injection of 40% glucose solution through the drain to the pleural cavity to increase adhesions.

Renal MR angiography at 1.0 T: three-dimensional (3D) phase-contrast techniques versus gadolinium-enhanced 3D fast low-angle shot breath-hold imaging

OBJECTIVE

The purpose of this study was to evaluate the diagnostic usefulness of three different MR angiographic techniques at 1.0 T.

SUBJECTS AND METHODS

In 22 patients with renal artery stenosis confirmed at intraarterial catheter angiography, we also performed unenhanced and gadolinium-enhanced three-dimensional phase-contrast MR angiography and gadolinium-enhanced single breath-hold three-dimensional fast low-angle shot MR angiography. We determined circulation time to optimize signal acquisition in gadolinium-enhanced breath-hold MR angiography after bolus injection of contrast material.

RESULTS

Sensitivity, defined as the detection of a hemodynamically significant stenosis (>50% luminal narrowing), was 85% for enhanced phase-contrast MR angiography, 91% for gadolinium-enhanced MR angiography, and 95% for unenhanced phase-contrast MR angiography. The combination of unenhanced phase-contrast MR angiography and gadolinium-enhanced MR angiography yielded 100% sensitivity for hilar artery stenoses. There were 13 false-positive findings with unenhanced phase-contrast MR angiography, 10 with enhanced phase-contrast MR angiography, and four with gadolinium-enhanced MR angiography (specificity: 38%, 52%, and 79%, respectively). Accessory renal arteries were not seen on unenhanced or enhanced phase-contrast MR angiography (0/8 patients) but were detected with gadolinium-enhanced MR angiography in five of the eight patients. Interobserver agreement (kappa = .62) was best with gadolinium-enhanced MR angiography. The quality of the images was unsatisfactory for adequate evaluation of segmental renal arteries with all three MR angiographic techniques.

CONCLUSION

A combination of unenhanced phase-contrast MR angiography and gadolinium-enhanced MR angiography at 1.0 T proved useful as a screening protocol for renal artery stenosis.

[Color duplex ultrasound of the finger arteries. An alternative to angiography?]

By means of modern color-coded duplex sonography (CCDS) even very small vessels can be visualized. Maximum resolution nowadays is about 0.5 mm diameter of the vessel. We compared the use of CCDS and angiography in studying of acral perfusion. Besides morphologic criteria, hemodynamic criteria were recorded. Arteries in healthy fingers appear as long and straight vessels with a clearly defined border. The physiological maximal blood flow velocity exceeded 20 cm/s. CCDS revealed tortuosity of finger arteries as typical finding in thrombangiitis obliterans. Segmental stenosis can either be identified morphologically or quantified by measurement of the flow velocity with poststenotic maximal systolic velocities of less than 20 cm/s or by the acceleration of the blood flow within the stenosis, as proven by angiographic examinations. CCDS is suitable for evaluation of acral perfusion in patients suffering from secondary Raynaud's syndrome. Apart from diagnosis of disturbed acral circulation, other possible applications of CCDS are in in the surgical field, for example replantations in hand or finger surgery.

Multiplex PCR for simultaneous detection of the most frequent T cell receptor-delta gene rearrangements in childhood ALL

A rapid and simple multiplex polymerase chain reaction (PCR) is described that is capable of identifying the six most frequent rearrangements of the T cell receptor (TCR)-delta gene segments in childhood acute lymphoblastic leukemia (ALL). The PCR products amplified in a single reaction are of different size for each TCR-delta gene rearrangement. Therefore, they are readily and unambiguously distinguished after agarose gel electrophoresis and assigned to a specific V-D-J gene rearrangement. There is no need for labor-intensive and time-consuming Southern blot hybridization or nested PCR. To evaluate the multiplex assay we chose 45 DNA samples of childhood ALL analyzed beforehand for TCR-delta gene rearrangements by Southern blot and single PCR of which 30 showed TCR-delta gene rearrangements. The multiplex PCR results corresponded to the Southern blot and single PCR analyses. The described multiplex PCR enables the detection of clonal markers in about 50% of patients in order to monitor minimal residual disease (MRD) in prospective studies with a high turnover of samples.

[Hypothenar hammer syndrome as a rare cause of Raynaud syndrome]

A 25-year-old carpenter with severe localised Raynaud syndrome of the lateral three fingers of his right hand is described. The patient reported digital ischaemia caused by cold or vibration, and especially when both were present simultaneously. He was initially diagnosed with thrombangitis obliterans, but failed to respond to intravenous prostaglandin therapy, pentoxifyllin or aspirin. Diagnostic procedures performed in our hospital, especially angiography, confirmed our suspicion of hypothenar hammer syndrome. Radiological examination revealed severe anatomical and functional changes of the distal ulnar artery and, digital arteries of the affected digits. The differential diagnosis of Raynaud syndrome should include the hypothenar hammer syndrome as a possible cause. Early diagnosis and prevention of hand trauma is the only possible way to stop progression of this disease, which leads to invalidity.

[The popliteal artery entrapment syndrome in an older patient. Its diagnosis after unsuccessful laser-assisted percutaneous transluminal angioplasty]

HISTORY AND FINDINGS

A 52-year-old patient complained of progressively increasing pain in his left leg when walking. The pain-free walking distance was 50-100 m. He was smoking about 20 cigarettes daily. No pulses were palpable in the left leg below the inguinal fossa. Recapillarisation time was normal in both legs and there were no trophic changes.

INVESTIGATIONS

The Doppler perfusion pressure values were up to 40 mm Hg less in the left than the right leg. Ankle oscillography record showed a definite stenosis curve on the left. Digital subtraction angiography of the left leg showed a short occlusion of the popliteal artery with many collaterals and atypical medical deviation of the artery. The findings were interpreted as indicating peripheral arterial vascular disease.

TREATMENT AND COURSE

Laser-assisted percutaneous transluminal angioplasty with balloon dilatation merely achieved a narrow lumen which again closed on plantar flexion of the left foot. The reversible occlusion suggested popliteal artery entrapment. At operation the popliteal artery coursed atypically over the dorsal medial aspect of the medial head of the gastrocnemius muscle. The arterial segment in the stenotic area was replaced by an autologous venous graft and the gastrocnemius muscle fixed laterally. The patients no longer experienced any impairment on walking and repeat angiography showed unimpeded flow through the graft even on plantar flexion.

CONCLUSION

Popliteal artery entrapment is rare in the elderly and may be overlooked without provocation test and complete visualisation of the leg and pelvic arteries.

[Foreign bodies in the digestive tract]

In the past two years time 128 patients-prisoners, who had swallowed foreign bodies, have been observed. Six anchors and crosses, which had been stuck in the esophagus, were immediately and successfully removed endoscopically. Long rods and crosses (60 cases) situated mostly in the stomach or descending part of the duodenum were operated without any complications. A few weeks delay of operation caused the covered perforation of the alimentary tract wall nearly 20% of cases and one of which died. Ingested small foreign bodies (less than 10 cm in length) are harmless, pass spontaneously through the gastrointestinal tract and don't need any surgical intervention. In a few cases those small foreign bodies perforated the guts, covered outside the digestive tract without any complaints.

[Inadvertant suture fixation of a Swan-Ganz catheter to the pulmonary artery following heart surgery]

We report a patient undergoing redo cardiac surgery for combined replacement of the aortic and mitral valves. During the course of the operation, a Swan-Ganz catheter - positioned preoperatively - was accidentally fixed to the wall of the pulmonary artery. As this did not interfere with cardiac output measurement or the pulmonary artery pressure wave form, the fixation was not noticed until an attempt was made to remove the catheter. Fluoroscopy revealed both the catheter's immobility and the location of the suture fixation. The patient required a sternotomy to remove the catheter. In order to avoid this complication, the indications for pulmonary artery catheters during cardiac surgery should be carefully considered. If catheters are inserted, their mobility should by all means be ensured before the chest is closed.

Eosinophilia-myalgia syndrome: findings at MR imaging and proton spectroscopy of the lower leg

Five magnetic resonance (MR) studies of the lower leg were performed in three patients with eosinophilia-myalgia syndrome (EMS). The 1H spectroscopic and imaging findings were compared with seven examinations of age-matched healthy controls. Standard imaging with proton density-, T1-, and T2-weighted spin-echo (SE) sequences at 1.5 T showed marked atrophy of the calf muscles and slightly increased signal strength of muscle tissue in T2-weighted SE images. The application of frequency selective chemical shift imaging (SENEX) exhibited skin changes similar to those of scleroderma with increased water content and thickened cutis in the water selective images. In one patient the tibialis muscles showed irregular structures, but no fatty degeneration as demonstrated in the fat selective images. Proton signals from volume elements of (20 mm)3 within the soleus and gastrocnemius muscle were recorded by the PRESS localization method. A reduction of the creatine/water and the choline/water ratios was found in the 1H spectra from the EMS patients compared to the controls. Localized 1H spectroscopy exhibited modified distributions of the lipid signals in two EMS patients with slightly elevated signals from unsaturated fatty acids. The transverse relaxation of choline and creatine signals was accelerated in both examinations of one patient compared with the healthy controls.

Hematopoietic reconstitution after bone marrow transplantation: assessment with MR imaging and H-1 localized spectroscopy

Magnetic resonance (MR) studies were performed in 14 patients as early as possible (21-110 days) after bone marrow transplantation (BMT). MR characteristics of lumbar vertebral bone marrow were studied with T1-weighted spin-echo imaging, water- and fat-selective imaging with a frequency-selective excitation technique, and point-resolved spatially localized proton spectroscopy. Signals from water and fat protons and their T1 and T2 values were analyzed. Water proton signal intensity correlated well with cellularity within bone marrow, as determined with parallel iliac crest biopsies. The fraction of signal from water in red bone marrow of patients with allogeneic transplants from siblings (four cases) was significantly higher than in four patients with autologous transplants. The latter showed very low cellularity in the period of about 4 weeks after BMT because of the cytotoxic pretreatment of the bone marrow. The MR results in six patients with allogeneic transplants from unrelated donors ranged widely, depending on the complications after BMT. Analysis of data obtained with the different techniques showed that water- and fat-selective MR imaging and spectroscopic methods are useful for noninvasive monitoring of hematopoietic reconstitution after BMT.

[Special MR methods for primary bone tumors: II. Volume selective 1H-spectroscopy]

The method of localised 1H MR spectroscopy was used in 19 examinations in 9 patients with primary bone tumours in order to obtain spectral signals and to determine whether these are specific for tumour classification. The spectra were obtained by a double spin echo method and the tumour tissue showed very high water content and only minor lipid and proton signals which showed J-coupling characteristics. The latter are not found in normal bone marrow and are probably due to products of tumour metabolism. The resolution of the spectra within a 13 mm or 20 mm tissue cube depends largely on the structural homogeneity of the tumour. The signal patterns in the spectra were not specific to histological tumour types.

[Special MR methods for primary bone tumors: I. Chemical shift selective imaging]

The value of selective imaging of fat and water compared with proton density, T1- and T2- weighted MR sequences was studied in the course of 32 examinations on 22 primary bone tumours in various parts of the body. Fat selective images showed practically signal free areas for osteogenic tumours which could be distinguished from surrounding fat containing soft tissues. Water selective images improved definition of the tumour margin from oedema in the bone marrow. Chemical shift artefacts are avoided by these methods and therefore fat and water selective images provide better spatial resolution for identical pixel sizes.