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J Neuerburg

Publications and source records attributed to J Neuerburg.

At least 19 recordsLinked to original sources
PubMed2005

New optional IVC filter for percutaneous retrieval--in vitro evaluation of embolus capturing efficiency.

PURPOSE: In-vitro evaluation of a new caval filter (Cook Celect Filter) developed for delayed percutaneous retrieval in comparison to the Gunther Tulip filter. MATERIALS AND METHODS: The new Celect filter is constructed on the basis of the Tulip filter and consists of 4 primary anchoring legs and additional 8 thinner secondary wires to stabilize the filter and to guarantee adequate filtering efficiency. The filtering wires are of the same amount and equal distribution as the filtering wires of the Tulip filter. The secondary wires are arranged in such a way that percutaneous filter retrieval should be possible even if the wires are incorporated into the caval wall. In a flow model (tube size ø15-, ø22- and ø30 mm), the filter was exposed to single and multiple emboli (blood clots) of different sizes (3 x 5, 3 x 10, 5 x 10, 3 x 20, 5 x 20, 7 x 10, 7 x 20 to 10 x 24 mm) to analyse the embolus capturing efficiency under different conditions including eccentric and concentric, horizontal and vertical positions in comparison to the Tulip filter. All testing was carried out in SPSS analytic software; statistical significance was assumed for p-values < 0.05. RESULTS: The in-vitro embolus capturing efficiency of the Celect filter proved to be equivalent to the Tulip filter. In the single-embolus test, 91.6 % of the clots were captured by the Celect filter and 87.2 % by the Tulip filter (p = 0.042). Large clots ranging from 7 x 10 to 10 x 24 mm were captured in all cases, whereas the capture rates for the 3 x 5-mm and 3 x 10-mm clots were lower. The filters captured significantly more clots in the concentric than in the eccentric location. There was no significant difference between the overall capture rates of the two filters in the multi-clot test (72.2 % vs. 75.1 %), which showed deterioration of filter function during multiple clot exposure. With the 15-mm tube, the Celect filter had a significantly higher capture rate than the Tulip filter, whereas it was lower with the ø30-mm tube. There was no significant difference between the filters in a ø22-mm tube. The pressure gradient across the filters when exposed to blood clots ranged from 4.9 - 7.4 mm Hg for the Celect filter and 5.7 - 6.8 mm Hg for the Tulip filter in the single-embolus testing. There was no significant difference in the multi-clot tests. CONCLUSION: The new Celect filter showed similar in-vitro capture properties as the Gunther Tulip filter and deserves further in-vivo testing.

Blood Flow Velocity↗
PubMed2003

[Percutaneous embolization of the kidney: indications and clinical results].

OBJECTIVE: Renal embolisation offers a minimal invasive means of renal ablation under primary palliative indication. We evaluated our experience with this technique in a series of 40 patients. PATIENTS AND METHODS: From 1996 to 2002 a total of 40 patients underwent total embolisation of the kidney. Our patients encompassed 15 females and 25-males (median age: 68 years, 46 - 89 years). In 15 patients indication for embolisation was to ablate a non-functioning kidney following obstruction due to advanced cancer, in 9 patients preoperatively with advanced renal cell carcinomas invading the vena cava, in 8 patients for control of hematuria and in 8 patients with non-operable advanced renal cancers. The embolisation was carried out in DAS-technique with a 7 Fr. selective catheter and central placement of macrocoils, from 2000 on we additionally performed a peripheral embolisation with polyvinylalcohol (PVA) particles. The intervention took place in epidural anesthesia. RESULTS: Perioperatively in all patients a complete occlusion of the renal artery as well as acessory arteries (n = 6) could be documented radiographically, perioperative complications were not observed. A post-embolisation syndrome occured in 32 patients. Reinterventions with repeat embolisation became necessary in 5 patients (persistent urine production-n = 4, persistent hematuria-n = 1). SUMMARY: The combined central and peripheral embolisation of the kidney in epidural anesthesia is a valuable means in selected patients under palliative indication for defunctionalisation of the kidney as well as control of hematuria.

Aged↗
PubMed2001

Prognostic significance of positron emission tomography using fluorine-18-fluorodeoxyglucose in patients treated for malignant lymphoma.

AIM: To evaluate the prognostic significance of positron emission tomography (PET) using fluorine-18-[2]-fluoro-2-deoxyglucose (FDG) in patients treated for Hodgkin's disease (HD) or non-Hodgkin's lymphoma (NHL) compared to conventional restaging (CRS). METHODS: Fifty-six patients with either HD (n = 22), high-grade NHL (n = 26) or centrocytic-centroblastic NHL (n = 8) were included. PET was performed in 41 patients for treatment reevaluation up to three months after therapy and in patients with persisting residual masses (n = 10) or suspected relapse (n = 5) four to twelve months after treatment. The scans were evaluated qualitatively and quantitatively using standardised uptake values (SUV). Progression-free survival (PFS) was estimated to assess the prognostic value of FDG PET and clinical follow-up was taken as gold standard. RESULTS: PET was positive in nineteen of 41 patients studied for treatment reevaluation. Progression was observed after a median interval of two months (range 0-15) in sixteen of 19 patients after a positive PET scan and in three of 22 patients after a negative scan (p < .001). Median duration of follow-up in progression-free patients was 21 months (range 6-72). In patients with a partial remission in CRS progression was more common in PET-positive than in PET-negative patients (5 of 7 vs. 1 of 14; p < .01) and positivity with PET was associated with poorer PFS (p < .0025). PET studies performed four to twelve months after treatment were true negative in seven, true positive in five and false-positive in three patients. SUV > 11.35 of lymphoma lesions was associated with poorer PFS than SUV < 11.35 (p < 0.025). CONCLUSION: We conclude that FDG PET after treatment of malignant lymphoma has a high prognostic value and should be recommended in patients with persistence of residual masses.

Adolescent↗
PubMed2000

[Pretherapeutic diagnosis of fibrous dysplasia].

A safe differentiation of fibrodysplastic lesions from "real" bone tumours is of high importance because a fibrous dysplasia often requires no further therapy. While polyostotic involvement of fibrous dysplasia can be safely diagnosed before therapy, in monostotic disease differential diagnostic problems may occur. In the present investigation only in 6 of 14 mon- and biostotic lesions caused by fibrous dysplasia a correct diagnosis could be established by radiologic methods. However, in all cases of fibrous dysplasia malignancy could be excluded by radiology and the false diagnosis had no therapeutic consequences.

Adolescent↗
PubMed1999

Value of intravenous cholangiography prior to laparoscopic cholecystectomy.

We performed a retrospective study on 163 patients for evaluation of the benefit of intravenous cholangiography prior to laparoscopic cholecystectomy. Radiographic evaluation of the various areas of the biliary system was classified regarding resolution of anatomic structures: well detailed (excellent), impaired image but reliable interpretation possible (good), insufficient contrast with limited assessment (poor), no reliable judgment possible (insufficient). The common bile duct could be described as "good" in 96.3%, whereas the cystic duct could be described as "good" in only 54.6%. Concrements of the gallbladder were recognized in 72.4%, and common bile duct stones were diagnosed in only two of three patients. A distal junction of the cystic duct was found in nine cases, but there was no influence on the following operative procedure. Only one of two patients with a short cystic duct was identified. We found no improvement after routine use of intravenous cholangiography concerning the evidence of common bile duct stones or the avoidance of lesions of the common bile duct. Hence routine use of intravenous cholangiography prior to laparoscopic cholecystectomy is not justified.

Bile Ducts, Intrahepatic↗
PubMed1999

[Diagnosis and visualization of renal artery stenosis by color-coded Doppler ultrasonography. Comparison of central and peripheral flow patterns].

PURPOSE: Comparison between central and peripheral flow patterns with color-coded duplex sonography in the diagnosis of renal artery stenosis. MATERIALS AND METHODS: In a prospective study with sixty-six patients systolic velocity (central examination) and acceleration index (peripheral examination) were determined using color-coded duplex sonography examination in order to detect and visualize renal artery stenosis. If the central and peripheral measurements were negative, no angiography was performed. In contrast, if one of the methods yielded a pathological finding, catheter angiography was performed to verify the results (21 patients), as well as in two other unclear cases. RESULTS: An agreement between central and peripheral measuring was seen in 49 of 66 patients. In ten patients central and peripheral measurements showed different results. In seven cases the peripheral measurements were not clear. Compared to angiography, peripheral measurement showed a sensitivity of 60%, a specificity of 75% and a positive predictive value of 81.8%. In contrast, central examination had a sensitivity of 100%, a specificity of 75% and a positive predictive value of 88.2%. CONCLUSIONS: Based on our preliminary results, the measurement of the systolic velocity peak seems to be an effective method to detect renal artery stenosis.

Adult↗
PubMed1999

[Transvenous liver biopsy].

In patients with an indication for histological evaluation of diffuse liver disease a transvenous approach may be advisable if a percutaneous technique is contraindicated by severe coagulopathy or ascites. In general, the procedure may be performed as an aspiration core, or forceps biopsy technique using a transjugular approach. Alternatively, the forceps biopsy technique may be performed via a transfemoral access. Adequate specimens for histologic diagnosis may be obtained in 77-100% with either biopsy technique. Complications after transvenous liver biopsies occur in 0-20% with an overall mortality rate below 0.5%. Although the transvenous liver biopsy techniques take more time and are more expensive than percutaneous biopsy techniques, they represent a safe and effective alternative for obtaining adequate liver samples for histological diagnosis in special clinical settings.

Biopsy↗
PubMed1999

[Clinical value of FDG PET for therapy monitoring of malignant lymphoma--results of a retrospective study in 72 patients].

AIM: Of the present retrospective study was to validate the clinical value of FDG-PET for therapy control of malignant lymphoma. METHOD: 72 patients (41 non-Hodgkin lymphomas, 29 Hodgkin's disease, 2 unclassified) received static FDG-PET scans of initially involved regions (n = 53) or of the entire neck and trunk (n = 19) after therapy. CT imaging (n = 70) and serum LDH measurement (n = 64) were also performed. Results were validated either by biopsy (n = 7) or by clinical follow-up (n = 65). The predictive value of PET was analysed in relation to different prognostic factors (stage, recurrence status, number of prior therapy regimen). RESULTS: PET obtained a sensitivity of 88%, a specificity of 83% and an overall accuracy of 85% for detection of residual disease. The values for CT were 84%, 31% resp. 54%, and for serum LDH 50%, 92% and 73%. The predictive value of PET was related to the prevalence of residual disease. PET predicted complete remission in more than 90% of patients with moderate risk (stage I-III, no relapse, no more than two different therapy regimens). In high risk patients, however, the negative predictive value of PET was 50-67%. CONCLUSION: FDG-PET is more accurate than CT imaging and LDH measurement for therapy monitoring of malignant lymphoma. Therapy success can be reliably predicted in patients with moderate risk.

Adolescent↗
PubMed1998

[Interventional MR tomography: equipment concepts].

Interventional MRI is one of the most recent developments of clinical MR imaging. Because of the development of open MR systems and very compact high-field systems, a number of interventional procedures are already possible today under MR control and will be tested in experimental and clinical investigations. The currently commercially available systems differ with respect to their static magnetic field strength, their gradient systems and patient access. In addition, there are differences concerning their space requirements and costs. All systems have components facilitating interventional procedures. In this article we discuss the advantages and shortcomings of these commercially available systems and look at future developments in interventional MR equipment.

Equipment Design↗
PubMed1998

[A new MR-(and CT-) compatible bone biopsy system: first clinical results].

PURPOSE: To describe the development and clinical evaluation of a new, hand-powered or alternatively motor-driven, MRI and CT compatible percutaneous bone biopsy system. MATERIALS AND METHODS: A new coaxial drill system (Cook Europe A/S) was designed for percutaneous, MR-guided bone biopsies and powered either by hand or an optional motor (10-250 rotations/minute using 6 bar [88.2 PSI] compressed air). The system has been used in 23 patients. Fourteen procedures were performed in a 1.5 T MR scanner (Philips-Gyroscan ACS-NT) which has an attached C-arm (Philips-BV 212-Angio) in case fluoroscopy is required, and 9 procedures in a CT scanner (Siemens-Somatom Plus). RESULTS: Driven by hand or by the pneumatic motor unit, the system achieved safe and accurate MR-guided access to all of the lesions and was even able to penetrate osteosclerotic lesions. MR- or CT-guided percutaneous biopsy yielded a correct diagnosis in all but 5 cases. No procedural complications occurred. CONCLUSION: MR-guided percutaneous bone biopsy performed with the new coaxial drill system was found to be safe and reliable, and suitable for obtaining histological specimens from skeletal lesions even when covered with thick cortical or sclerotic bone.

Biopsy↗
PubMed1998

Thrombolysis of mural thrombus by ultrasound: an experimental in vitro study.

RATIONALE AND OBJECTIVES: The authors perform an in vitro evaluation of the thrombus fragmentation to determine the efficacy and degree of downstream clot fragment embolization that occurs during transcatheter ultrasound treatment of fibrin-rich mural thrombus in a peripheral venous flow model with variable diameter tubing. METHODS: The authors used a 22.5-kHz prototype intravascular ultrasound device with a flexible 0.8-mm (.032-inch) titanium wire probe encased in a 7-French teflon guide catheter, at the tip of which is a 2-mm ball. In 50 silicone tube segments (inner diameter 3, 5, 7, 9, and 11 mm; n = 10 each), firmly adherent mural thrombus was produced using bovine blood in a modification of the Chandler's loop technique. Ultrasound energy (30-36 watts/cm), maximal longitudinal catheter tip amplitude 70 m) was applied to the thrombus while a continuous flow of water was maintained in the closed loop system. Clot fragment emboli were trapped in "downstream" polyethylene filters. RESULTS: The mean rate of thrombus removal ranged from 99% +/- 0.3% in the 3-mm segments to 76% +/- 6% in the 11-mm segments. The average weight of the fragments that embolized "downstream" and were trapped in the filters, expressed as a percentage of the initial clot weight, was 11% in the 3-mm segment, 14% in the 5-mm segment, 30% in the 7-mm segment, 29% in the 9-mm segment, and 28% in the 11-mm segments. The majority of the embolized fragments appear to be larger than 1 mm. CONCLUSIONS: In this in vitro venous flow model a lack of catheter steerability was the major obstacle to complete thrombus fragmentation in vessel calibers larger than two times the tip diameter. The rate of embolism and the amount of remaining thrombus that could not be removed from the vessel were higher in the larger vessels.

Animals↗
PubMed1998

Declotting of embolized temporary vena cava filter by ultrasound and the Angiojet: comparative experimental in vitro studies.

RATIONALE AND OBJECTIVES: The authors perform an in vitro evaluation of the thrombolytic efficacy and the amount of "downstream" embolization induced by two new mechanical thrombectomy devices when applied to clots trapped in a temporary vena cava filter. METHODS: The first device used was a 22.5-kHz prototype intravascular ultrasound device with a flexible 0.8-mm (.032-inch) titanium 2-mm ball-tipped wire probe ensheathed in a 7-French teflon guide catheter. The device was inserted through a 10-French steering catheter. Under fluoroscopic control, ultrasound energy (26 +/- 4 watts/cm2, maximal longitudinal catheter tip amplitude 54 microm) was applied to 10 Ultravist-filled porcine thrombi (mean, 3500 mg). The second device, the Angiojet catheter, was applied to five Ultravist-filled porcine thrombi (mean, 3640 mg). The thrombi were treated while trapped in a temporary Günther vena cava filter (Cook Europe, Bjaverskov, Denmark) mounted in a vena cava flow model. The resultant "downstream" emboli were trapped in two tandem filters of decreasing pore size and weighed. RESULTS: Mean thrombus dissolution rate was 53% +/- 22% standard deviation (SD) for the ultrasound device (n = 10) and 63 % +/- 8% SD for the Angiojet (n = 5) (difference statistically significant at P = 0.03). For the ultrasound device, the mean embolic particle weight caught by the filters with mesh widths of 1 mm and 0.1 mm was 42% +/- 14% SD and 4% +/- 2% SD, respectively, of the initial thrombus weight. For the Angiojet, the respective numbers were 35% +/- 16% SD and 3% +/- 1% SD. Mean treatment time was 216 +/- 45 seconds SD for the ultrasound device and 153 +/- 21 seconds SD for the Angiojet. CONCLUSIONS: The thrombolytic efficacy of the Angiojet was significantly greater and the treatment time was significantly shorter than that of the ultrasound device. Both systems had a high embolization rate.

Animals↗
PubMed1998

Positron emission tomography with 18F-FDG to detect residual disease after therapy for malignant lymphoma.

We retrospectively evaluated the use of 18F-FDG PET for assessment of residual disease in 27 patients after therapy for malignant lymphoma. The images were evaluated qualitatively and quantitatively using standardized uptake values (SUV). All findings were validated either by biopsy or by clinical follow-up and compared with corresponding CT findings. The impact of blood glucose concentration, body weight, body surface area, lesion diameter and the time between injection and imaging on the SUVs were analysed. All 15 patients with biopsy-proven residual disease or relapse during follow-up and 11 of 12 patients who remained relapse-free were correctly identified by qualitative interpretation of the PET images. A case of pneumonitis after radiotherapy/chemotherapy accounted for the only false-positive finding. Compared with CT imaging, PET had a significantly higher specificity (P < 0.01), accuracy (P < 0.05) and positive predictive value (P < 0.05). The mean and maximum SUV of the tumour lesions were positively correlated to lesion diameter (P < 0.01) and imaging time post-injection (P < 0.01). Standardized uptake values corrected for the partial volume effect and normalized to a standardized imaging time (SUVBPT) were significantly higher (P < 0.05) in high-grade than in low-grade non-Hodgkin's lymphoma. In conclusion, 18F-FDG PET may help in the identification of patients who need additional treatment after the completion of conventional therapy. Qualitative image interpretation appears sufficient for this purpose.

Adolescent↗
PubMed1997

Catheter visualization using locally induced, actively controlled field inhomogeneities.

A new technique for visualization of interventional devices using MR is presented. A prototype catheter was equipped with a thin copper wire loop, leading from the proximal end to the tip and back. A small current (10-150 mA) through these two parts of a wire induces a local magnetic field along the catheter. Introduction of this catheter into the main magnetic field of the MR imager locally disturbs the homogeneity of the magnetic field. Image locations within the locally induced fields appear dark due to signal loss, and the extent of this effect can be varied during the procedure by simply adjusting the current. Different dedicated wire configurations allow visualization of the catheter in its whole length or in parts, i.e., with markers for balloons. Fast gradient echo sequences that provide a bright signal from inflowing blood are used for rapid imaging.

Animals↗
PubMed1997

[Endosonography control of percutaneous paracoccygeal drainage of deep pelvic abscesses after rectum resection].

Pelvic abscesses are severe complications after rectal surgery. In recent years, surgical drainage has been edged out by percutaneous drainage techniques. We report our experience with the drainage of postoperative pelvic abscesses via the paracoccygeal route controlled by endosonography. In eight patients the diagnosis of a retrorectal pelvic abscess was established by endosonography and confirmed by endosonographically controlled exploratory puncture. Drainage of the abscesses was performed via the paracoccygeal access route by trocar or Seldinger technique under permanent visual control by endoluminal sonography. Irrigation of the abscess cavity was than performed daily. In all cases drainage was successful without complications. Duration of drainage was 9-14 days with a mean of 10.8 days. In one patient there was a recurrence of the abscess because of early removal of the drainage catheter. Because of its overall availability and its good results, paracoccygeal percutaneous endosonographically controlled drainage seems to be a suitable uncomplicated method for drainage of postoperative pelvic abscesses.

Abdominal Abscess↗
PubMed1997

[Catheter visualization in MR-tomography: initial experimental results with field-inhomogeneity catheters].

PURPOSE: To assess the feasibility of a new developed field inhomogeneity catheter for interventional MR imaging in vivo. MATERIALS AND METHODS: Three different prototypes of a field inhomogeneity catheter were investigated in 6 pigs. The catheters were introduced in Seldinger technique via the femoral vessels over a guide wire on an interventional MR system (Philips Gyroscan NT combined with a C-arm fluoroscopy unit [Philips BV 212]). Catheters were placed in veins and arteries. The catheter position was controlled by a fast gradient echo sequence (Turbo Field Echo [TEE]). RESULTS: Catheters were introduced over a guide wire without complications in all cases. Using the field inhomogeneity concept, catheters were easily visualised in the inferior vena cava and the aorta by the fast gradient echo technique on MR in all cases. Although aortic branches were successfully cannulated, the catheters were not displayed by the TFE technique due to the complex and tortuous anatomy. All animals survived the experiments without complications. CONCLUSION: MR guided visualization of a field inhomogeneity catheter is a simple concept which can be realised on each MR scanner and may allow intravascular MR guided interventions in future.

Animals↗
PubMed1997

[Flow direction-sensitive spin-echo MR angiography].

New blood pool contrast agents yield a significant shortening of T1 of blood. Consequently, the usual techniques of time-of-flight and phase-contrast angiographies cannot produce angiograms sensitive to one flow direction, even if saturation slabs are applied. It was our aim to test the hypothesis of displaying arterial and venous flow selectively with a specially designed spin echo sequence even after administration of contrast agents. Parallel slice selective 90-degree and 180-degree pulses were applied. The distance between slices could be varied. It was attempted to obtain MR angiographies that were flow sensitive for one direction only. We performed flow phantom studies without the use of contrast media and first in vivo experiments in pigs after administration of iron oxide particles. With our modified spin echo sequence unidirectional flow can be displayed, whereas stationary tissue is totally suppressed. There are no special demands for the hardware and no additional postprocessing needs to be performed. The locally off-centred 90-degree and 180-degree pulses are responsible for this. Exclusively, protons excited by the 90-degree pulse and flowing into the slice of the 180-degree pulse will be refocused and only such protons will give rise to signal in the images.

Animals↗