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J Neuerburg

Publications and source records attributed to J Neuerburg.

At least 37 records · Page 2Linked to original sources
PubMed1997

[T1-weighted excretory MR urography using GD-DTPA after low-dose diuretic administration].

PURPOSE: Assessment of the morphology of the urinary tract by gadolinium (Gd)-enhanced T1-weighted MR-urography (MRU) and precontrast diuretic injection. METHODS: MRU was performed in 5 patients using Gd-DTPA-enhanced coronal T1-weighted 3D-gradient-echo sequences with different spatial resolution. Prior to contrast injection, 10 mg of furosemide were administered intravenously. RESULTS: Secondary to the precontrast furosemide injection, the increase of the renal excretion rate allows complete visualisation of the entire collecting system within 10 minutes following Gd injection. Maximum intensity projections provide a three-dimensional overview of the ureters separate from the bladder. To achieve detailed anatomic imaging of the calices, both optimal distension and high resolution sequences are prerequisites which cannot be realized by means of survey urograms only. CONCLUSIONS: Contrast-enhanced excretory MRU performed after injection of a diuretic offers a rapid approach to visualising the morphology of the nondilated urinary tract. Imaging of caliceal details must be done with high-resolution 3D-gradient-echo sequences.

Adult↗
PubMed1997

[Cava filter placement under MRI control. Experimental in vitro and in vivo studies].

PURPOSE: An instrument has been developed for the introduction of caval filters which can be used with MRI; it has been investigated in in vitro and in in vivo experiments. MATERIAL AND METHOD: The ferromagnetic components of a commercially available instrument for the femoral introduction of the MR-eye Tulip IVC filter were changed for similar, non-ferromagnetic parts and the lock and dilator marked with dysprosium oxide rings. The instrument was used in a flow phantom and in animal experiments (two domestic pigs) in order to insert filters under MRI control on a 1.5 T Philips Gyroscan with integrated mobile digital subtraction angiography. RESULTS: Both in vitro and in vivo, the introducer, catheter and caval filter could be identified by MRI and positioned under MRI control. The position of the filter as indicated by MRI corresponded with radiological and macroscopic findings in all cases (5 phantoms, 2 pigs). CONCLUSION: The early experimental results indicate that percutaneous introduction of caval filters with placement under MRI control is possible.

Animals↗
PubMed1997

Interventional magnetic resonance. Initial clinical experience with a 1.5-tesla magnetic resonance system combined with c-arm fluoroscopy.

RATIONALE AND OBJECTIVES: The authors evaluate the feasibility of performing magnetic resonance (MR) procedures on a 1.5-tesla (T) system combined with conventional c-arm fluoroscopy. METHODS: A 1.5-T MR imaging system was combined with a conventional c-arm fluoroscopy unit in one room. The two systems were connected via a floating table top. Twenty-six interventional procedures (biopsies, MR-portography, percutaneous alcohol injection, laser ablation, fluid aspiration, and breast marking) were performed in 22 patients under MR, fluoroscopic control, or both. For MR guidance, fast gradient echo sequences were used, initiated from a panel at the front of the magnet. Images were displayed on an liquid crystal display screen positioned on the magnet. RESULTS: All MR-guided procedures were performed successfully without complications. The addition of c-arm fluoroscopy was useful for bone interventions and MR-portography. All diagnostic biopsies yielded sufficient amounts of tissue for histologic diagnosis. In breast lesions, the target identified on dynamic MR imaging was marked correctly in each case. In interstitial laser thermotherapy the laser effect could be visualized, and in percutaneous ethanol injection the distribution of the alcohol could be seen. Both imaging systems worked without image distortions and high-quality MR images were obtained. CONCLUSIONS: The combination of a 1.5-T MR imager with a c-arm fluoroscopy system seems to be a promising technical solution for performing interventional MR procedures.

Adult↗
PubMed1997

Perigraft inflammation due to Dacron-covered stent-grafts in sheep iliac arteries: correlation of MR imaging and histopathologic findings.

PURPOSE: To evaluate with magnetic resonance (MR) imaging the inflammatory perigraft response after implantation of Dacron-covered and noncovered arterial endovascular prostheses in sheep. MATERIALS AND METHODS: Four prosthesis types--two Dacron-covered nitinol stent-grafts (plain and heparin-coated) and two noncovered nitinol stents (Memotherm and Cragg)--were each inserted into the external iliac arteries of eight sheep. MR imaging before and after gadolinium enhancement was performed 5-8 days and 1 month after implantation (before the animals were killed). Macroscopic and microscopic examinations of the vessels were performed, and findings were correlated with those on MR images. RESULTS: Severe inflammatory perigraft responses to the heparin-coated Dacron-covered stent-grafts were found; MR images demonstrated contrast enhancement and edema. Macroscopic examination showed marked vascular wall thickening and adhesions around the Dacron fabric; microscopic examination showed a pronounced inflammatory foreign-body response. There was a moderate inflammatory response to the plain Dacron-covered stent-grafts and almost no response to noncovered stents. CONCLUSION: In sheep, MR imaging findings of perigraft soft-tissue edema and contrast enhancement correlated well with histopathologic findings of severe perigraft inflammation due to heparin-coated Dacron-covered stent-grafts.

Alloys↗
PubMed1997

[Comparison of findings with 18-FDG PET and CT in pretherapeutic staging of malignant lymphoma].

AIM: Comparison of diagnostic efficiency of FDG-PET and CT regarding localisation, histology, size and FDG-uptake of a lesion. METHODS: CT- and FDG-PET studies of 27 patients with histologically confirmed malignant lymphoma as primary disease or relapse were evaluated retrospectively. In CT lesions with a diameter (DCT) > 15 mm were regarded as positive. Focal accumulations of FDG, not explained by physiological metabolism, found by visual interpretation in iterative reconstructed PET-scans, were quantified for diameter (DPET) and corrected standardized uptake value (SUV), corrected for partial-volume-effect. Lesions were classified depending on histology and lesion quality (lymph nodes, bulks, extranodal lesions). RESULTS: CT detected 78 lesions in 26 patients, all confirmed by FDG-PET. PET localized 18 additional lesions (+23%); in high grade NHL +25%. Both methods were equally efficient in cervical lymph nodes and lung lesions, in all other regions of lymphatic nodules and in case of liver and spleen lesions PET localized more lesions. SUV was significantly higher in high-grade NHL (19.0) than in low-grade NHL and Hodgkin's disease (10.6 resp. 11.1). DCT and DPET correlated significantly (r = 0.75). CONCLUSION: Diagnostic efficiency of FDG-PET is equivalent or superior to CT in staging of malignant lymphoma before therapy. Qualitative interpretation seems sufficient for staging, quantitative analysis may add information about malignancy grade in NHL.

Fluorodeoxyglucose F18↗
PubMed1997

[Preoperative diagnosis of laparoscopic cholecystectomy. Is there an indication for routine intravenous cholangiography?].

In a retrospective study including 163 patients we investigated the necessity of i.v. cholangiography in preoperative routine diagnostic workup prior to laparoscopic cholecystectomy. We evaluated the evidence of i.v. cholangiography concerning the anatomy of the biliary system, the evidence of common bile duct or cystic duct stones and the influence on the further therapeutic procedure. While the common bile duct could be demonstrated in 96.3%, the cystic duct could be visualized in only 54.6%. One out of two patients with a short cystic duct was identified. Stones in the gallbladder were recognized in 72.4% of cases, while only two out of three patients with common bile duct stones were diagnosed. In nine cases a deep junction of the cystic duct was found, but there was no influence on further operative procedure. Thus we found no improvement after routine use of i.v. cholangiography concerning the evidence of common bile duct stones or avoidance of intraoperative lesions of the common bile duct. The routine use of i.v. cholangiography prior to laparoscopic cholecystectomy is therefore not justified.

Adolescent↗
PubMed1996

Dynamic Gd-enhanced MR imaging of hepatic hemangioma: is high temporal resolution requisite for characterization?

We assessed the value of high temporal resolution in the dynamic characterization of hepatic hemangioma with use of magnetization-prepared gradient-echo (MP-GRE) imaging. Single-level inversion recovery incremental flip angle MP-GRE images were obtained in 26 patients with 34 hemangiomas before and at a repetition rate of 30 images/min after injection of Gd-DTPA without breath-holding. Enhancement patterns and temporal changes thereof were analyzed. Hemangiomas were categorized as small ( < 2.0 cm), medium (2.0-5.0 cm), and large ( > 5 cm) lesions. Classic early peripheral nodular enhancement (PNE) with progressive hyperintense fill-in was observed in 31 lesions (91%). Two of 10 small and 1 of 20 medium lesions showed complete fill-in within 10 s, and three small and one medium lesions within 45 s after the onset of PNE. In no cases of hemangioma was immediate homogenous hyperintensity observed without preceding PNE. In conclusion, temporal resolution of less than 10 s is a prerequisite for confident dynamic characterization of some hemangiomas, predominantly small hemangiomas.

Contrast Media↗
PubMed1996

[Determining the effectiveness of percutaneous cava filters: experimental studies].

PURPOSE: In vitro clot-trapping capacity of 16 different caval filters should be evaluated under varying experimental conditions. MATERIAL AND METHODS: In a flow model simulating in vivo conditions (soft latex tube, dextran solution at 37 degrees C, pulsatile flow at a mean rate of 3 1/min) the efficiency of 16 caval filters was evaluated in horizontal and vertical position by using 640 or 1280 clots/filter (8 sizes). Non-self centering filters were tested in centric and in tilted position. RESULTS: Efficiency of optimally centered caval filters varied between 97.8 and 69.4%. The largest thrombi were captured by all optimal centered filters. A change from vertical to horizontal position of the flow model resulted in a variation of filter efficiency by about 4.8%. Efficiency of non-self centering filters decreased significantly when placed in a tilted position (mean decrease 15.5%; range 2.7%-37.7%) resulting in a deterioration of the capture rate by as much as 43.2%. CONCLUSION: Under optimal study conditions efficiency of all evaluated caval filters was high. Tilting of caval filters resulted in a significant efficiency decrease.

Animals↗
PubMed1995

[The MR tomography of avascular necrosis of bone: the primary findings and the follow-up observations after core decompression].

PURPOSE: To assess the signal changes of avascular bone necrosis after core decompression. PATIENTS AND METHODS: 17 patients with avascular epiphyseal necrosis were examined by MRI using T1-weighted spin echo sequences before and after gadopentetate dimeglumine application, T2-weighted spin echo sequences and in some patients with fat-saturated 2D gradient echo sequences up to 22 months after core decompression. RESULTS: All patients but one recovered from symptoms after core decompression. Although the signal morphology of the necrotic area remained unchanged in the majority of the cases, a decrease of the joint effusion was observed as well as an ongoing signal increase after gadopentetate dimeglumine application. The last examinations displayed similar signal characteristics as on the preoperative scans; however, a reduction of the necrotic zone became evident. CONCLUSIONS: The decrease of joint effusion indicates successful core decompression, while a persistent signal increase after gadopentetate dimeglumine application reflects the viability of the necrotic area as well as an ongoing healing process.

Adult↗
PubMed1995

[The diagnosis and fragmentation therapy of acute massive pulmonary embolism with a rotatable pigtail catheter: experimental studies].

PURPOSE: A dedicated pigtail catheter system which allows angiographic documentation and adjunctive mechanical fragmentation of pulmonary emboli was evaluated in an animal experiment. MATERIAL AND METHOD: The 5-F catheter provided with an oval side hole proximal to the pigtail tip was rotated manually or with an electric drive, and with the wire as a rotation axis. Pulmonary embolic occlusions were recanalized in ten dogs. Catheter positioning, monitoring, rotation behaviour, safety and fragmentation properties were assessed. RESULTS: The catheter system was rapidly positioned and easily monitored in the pulmonary arteries. On average, 55% (+/- 20%) of the embolic occlusions were recanalized. Embolus fragmentation reduced the emboli-induced increase of the pulmonary arterial mean pressure by 72%. In three dogs, histology revealed slight perivascular haemorrhage. CONCLUSION: Partial recanalisation of the pulmonary arteries was achieved rapidly with relative ease of instrumentation. Since fragmentation technique is an adjunct to the commonly performed pigtail catheterization of the pulmonary arteries, no special training is required.

Acute Disease↗
PubMed1994

Dynamic contrast-enhanced MR imaging of the upper abdomen: enhancement properties of gadobutrol, gadolinium-DTPA-polylysine, and gadolinium-DTPA-cascade-polymer.

The enhancement properties of gadobutrol (40 and 80 mumol/kg body weight, 550 daltons), gadolinium-DTPA-polylysine (20 mumol/kg body weight, 53,000 daltons) and gadolinium-DTPA-cascade-polymer (20 mumol/kg body weight, < 30,000 Daltons) were investigated in abdominal MR imaging using a pig model (n = 24). Signal intensities before and after contrast media application were assessed using a fast single slice FLASH sequence. Measurements were made every 4 s within the first 116 s, every minute between 4 and 10 min and after 15, 20, 30, 40, 50, 60, 90, and 120 min after contrast media injection. Injection of gadobutrol resulted in typical signal intensity curves characterizing it as an extracellular agent similar to gadopentetate dimeglumine. Significant enhancement was found in all tissues except the trunk muscles when the lower dose was administered. Gadolinium-DTPA-polylysine injection resulted also in significant enhancement of the liver, the pancreas, and the renal cortex, but not of the trunk muscle, reflecting its blood pool properties known also from other macromolecular contrast agents. The signal intensity curves obtained after gadolinium-DTPA-cascade-polymer injection were similar to those obtained after polylysine injection, stressing the blood pool character of this new type of blood pool agent.

Abdomen↗
PubMed1994

[The magnetic resonance tomography of osteochondrosis dissecans of the knee joint after intravenous gadolinium-DTPA administration].

20 patients with osteochondritis dissecans were studied by MRI over a period of 3-34 months in order to observe healing and determine the viability of the loose fragment. After intravenous contrast, there was increased signal intensity at the junction between the fragment and the epiphyseal bed on T2-weighted sequences; this was interpreted as fibrous granulation tissue surrounding the fragment. The fragments themselves also showed increased signal intensity after gadolinium-DTPA. Intravenous gadolinium allows accurate evaluation of the junctional zone between the fragment and the epiphyseal bed by demonstrating fibrous, vascularised granulation tissue. This can be distinguished from synovial fluid, and it also demonstrates viability of the fragment.

Adolescent↗
PubMed1993

[An increase in cardiopulmonary exercise tolerance after the embolization of a pulmonary arteriovenous fistula].

A 21-year-old woman suffering from increasing dyspnoea on intense physical exercise, was found to have a congenital right-sided arteriovenous pulmonary fistula. This was successfully and without complication embolized using a percutaneously introduced Gianturco wire coil. All symptoms disappeared after this procedure. Definite improvement in physical performance, in comparison with pre-embolization values, was documented by spiroergometry as early as two days later (oxygen uptake 1855 vs. 1459 ml/min; anaerobic threshold 920 vs. 790 ml/min; oxygen-pulse 10.6 vs. 8.0 ml/beat; oxygen partial pressure 77.5 vs. 67.6 mmHg; alveolar arterial oxygen difference 33 vs. 44 mm Hg). Further constant subjective and objective improvement in physical performance was demonstrated 3 months after embolization. This case confirms that embolization of a pulmonary arteriovenous fistula can rapidly achieve lasting improvement in exercise performance.

Adult↗