Biomedical subjects

P Haage

Publications and source records attributed to P Haage.

At least 37 records · Page 2Linked to original sources

PubMed2001

US-guided nephrostomy with the aid of a magnetic field-based navigation device in the porcine pelvicaliceal system.

PURPOSE: To assess the technique and feasibility of ultrasound (US)-guided nephrostomy performed with the aid of a magnetic field-based navigation device. MATERIALS AND METHODS: Twelve percutaneous nephrostomy procedures were performed in seven domestic pigs under real-time US guidance employing a navigation system. Two magnetic field sensors registered the actual position of the puncture needle and the US transducer. The actual needle position and the aimed puncture tract were graphically projected into the real-time US images, allowing exact navigation of the needle. After placement of the needle into the renal pelvis, the nephrostomy tube was inserted by means of the Seldinger technique. RESULTS: The puncture procedure was successfully performed in each case. The renal pelvis was punctured in a single attempt in 10 of 12 cases. In two cases, multiple attempts were necessary because bending of the puncture needle led to inaccuracies of the navigation system. With exception of two small perirenal urinomas, no complications were seen. CONCLUSIONS: The magnetic field-based navigation device allows easy and accurate performance of nephrostomy guided solely by US.

Animals↗

PubMed2001

[Gadolinium-enhanced T(1)-weighted MR urography versus T(2)-weighted (HASTE) MR urography in children].

PURPOSE: To evaluate gadolinium-enhanced T(1)-weighted excretory MR urography (EMRU) versus T(2)-weighted (HASTE) MR urography in children with upper urinary tract abnormalities. PATIENTS AND METHODS: In a prospective study 63 children, aged from 3 weeks to 15 years, underwent MR urography in a 1.5-T scanner. Before and after an intravenous injection of 0.05 mg/kg body weight of furosemide, respiratory-triggered HASTE images were obtained for T(2)-weighted MR urography. EMRU was performed subsequent to i. v. gadolinium injection with respiratory-gated, coronal 3 D-gradient-echo sequences. RESULTS: Compared to T(2)-weighted (HASTE) MR urography, gadolinium-enhanced MR urography revealed a superior diagnostic accuracy in non-dilated collecting systems (horseshoe kidneys, ectopic kidneys, duplex systems, single ectopic ureters, ureteroceles). EMRU and T(2)-weighted (HASTE) MRU turned out to be equivalent in the assessment of obstructed but normal functioning upper urinary tracts (UPJ obstructions, megaureters). Non-functioning dilated collecting systems and multicystic dysplastic kidneys were best visualized with use of T(2)-weighted (HASTE) MR urography. CONCLUSION: Respiratory-gated gadolinium-enhanced T(1)-weighted MRU allows accurate evaluation of most upper urinary tract abnormalities. T(2)-weighted (HASTE) MRU complements GMRU in the evaluation of non-functioning renal units and cystic disease of the kidneys.

Adolescent↗

PubMed2001

Mechanical delivery of aerosolized gadolinium-DTPA for pulmonary ventilation assessment in MR imaging.

RATIONALE AND OBJECTIVES: To evaluate a new technique with mechanical administration of aerosolized gadolinium (Gd)-DTPA for MR visualization of lung ventilation. METHODS: Ten experimental procedures were performed in six domestic pigs. Gd-DTPA was aerosolized by a small-particle generator. The intubated animals were mechanically aerosolized with the nebulized contrast agent and studied on a 1.5-T MR imager. Respiratory gated T1-weighted turbo spin-echo images were obtained before, during, and after contrast administration. Pulmonary signal intensity (SI) changes were calculated for corresponding regions of both lungs. Homogeneity of aerosol distribution was graded independently by two radiologists. RESULTS: To achieve a comparable SI increase as attained in previous trials that used manual aerosol ventilation, a ventilation period of 20 minutes (formerly 30 minutes) was sufficient. Mean SI changes of 116% were observed after that duration. Contrast delivery was rated evenly distributed in all cases by the reviewers. CONCLUSIONS: The feasibility of applying Gd-DTPA as a contrast agent to demonstrate pulmonary ventilation in large animals has been described before. The results of this refined technique substantiate the potential of Gd-based ventilation MR imaging by improving aerosol distribution and shortening the nebulization duration in the healthy lung.

Aerosols↗

PubMed2001

Individually adapted examination protocols for reduction of radiation exposure in chest CT.

RATIONALE AND OBJECTIVES: To develop a simple directive for the reduction of radiation exposure without loss of diagnostic information in routine chest CT examinations. METHODS: Two hundred fifty adult patients (164 male, 86 female) were entered into a prospective trial. All examinations were performed with a multislice CT technique (Somatom Volume Zoom, Siemens). Four groups of 50 patients each were scanned with patient-related specific parameters: individual mA-s values were derived from the estimated body weight: kilograms + 10, +/- 0, - 10, and - 20 mAs. The results were compared with those of 50 patients who were examined by a standard chest protocol by using the parameters 120 mAs and 140 kV. All other parameters including the tube voltage were kept constant. Subjective image quality was rated on a three-point scale: 1 = excellent, 2 = fair, 3 = nondiagnostic. In addition, objective criteria based on signal-to-noise measurements were assessed by using a region-of-interest methodology. RESULTS: Image quality was sufficient in all cases. Mean subjective gradings of image quality, based on soft-tissue window settings, were 1.1 for the 120-mAs protocol, 1.1 for the (body weight [kg] + 10) mAs protocol, 1.1 for the (body weight [kg] +/- 0) mAs protocol, 1.3 for the (body weight [kg] - 10) mAs protocol, and 1.2 for the (body weight [kg] - 20) mAs protocol. Objective criteria based on noise measurements showed mean +/- standard deviation values of 5.7 +/- 0.8 Hounsfield units (HU) for the 120-mAs protocol. For the reduced-dose protocols, values were calculated as 7.6 +/- 1.2 HU (group + 10), 7.9 +/- 1.3 HU (group +/- 0), 8.7 +/- 1.2 HU (group - 10), and finally 9.1 +/- 1.3 HU (group - 20). The best correlation for an entire subgroup was achieved with the - 10 protocol (body weight [kg] - 10) mAs, with nearly constant noise related to body weight in all patients. CONCLUSIONS: By deriving mAs values from body weight estimation, an individually adapted protocol for chest CT can be recommended and easily employed in a clinical setting. With an adaptation of the tube current-time product based on the estimated body weight of the patient - 10 (body weight [kg] - 10 mAs), a well-balanced examination without significant loss of information, even in soft-tissue window settings, can be performed with this particular scanner. For this adapted mAs protocol, a mean reduction of radiation exposure of 45% was achievable, compared with the standard protocol. A maximum decrease per case down to 31 mAs was obtained, without relevant loss of image quality. Therefore, for other types of CT scanners, analogous protocols may be adapted.

Adult↗

PubMed2001

Prototype percutaneous thrombolytic device: preclinical testing in subacute inferior vena caval thrombosis in a pig model.

PURPOSE: To develop an animal model of subacute inferior vena caval (IVC) thrombosis and apply this model in evaluating the safety and efficacy of a prototype percutaneous thrombolytic device for restoring patency. MATERIALS AND METHODS: In 11 pigs, a stent with a ligature in the middle was placed in the IVC. Thrombin was injected to induce thrombosis. Hemostasis was achieved by using an occlusion balloon. The stent was ligated to prevent thrombus migration. Five to 8 days after thrombus induction, the ligature was broken and the stent fully deployed. In 10 animals, thrombectomy was performed by using the percutaneous thrombolytic device. A vena caval filter was inserted at the beginning of each declotting procedure. Thrombus removal percentage was estimated and pulmonary angiograms obtained to detect embolism before and after thrombectomy. The IVC was analyzed histologically. To determine thrombus composition, one animal was sacrificed without thrombectomy. Concerning procedural safety, failure of the stent delivery system, stent migration, and venous perforation due to balloon inflation and the stent placement or thrombectomy procedure were evaluated. RESULTS: Thrombus creation was successful in all animals. Fragmentation led to 75%--100% thrombus removal with flow restoration in all cases. There were no episodes of stent delivery failure, stent migration, or venous perforation. No significant pulmonary embolism was observed. In one case, a vessel dissection was identified at histologic examination. CONCLUSION: In this animal model of IVC thrombosis, the percutaneous thrombolytic device is effective and safe for clot removal.

Animals↗

PubMed2001

Silicosis-induced pulmonary artery stenosis: demonstration by MR angiography and perfusion MRI.

Silicosis is a common occupational disease. We present a 64-year-old male patient suffering from symptomatic silicosis due to compression of the pulmonary arteries by enlarged hilar lymph nodes. Clinical symptoms and diagnostic imaging modalities are described, with emphasis on cross-sectional imaging. MR angiography and perfusion MRI of the lung in silicosis are described, and their diagnostic value in pneumoconiosis is discussed.

Arterial Occlusive Diseases↗

PubMed2001

Diagnosis of pulmonary arterial hypertension and pulmonary embolism with magnetic resonance angiography.

BACKGROUND: Pulmonary magnetic resonance angiography (PMRA) has been proven to be accurate for the diagnosis of suspected acute or chronic pulmonary embolism (PE). Only limited data exist on the reliability of PMRA for the diagnosis of acute and chronic pulmonary artery hypertension (PAH). The aim of this study was to determine the accuracy of PMRA in the differentiation between patients suffering from PAH of varying etiologies. METHODS: Fifty patients (21 women; mean [+/- SD] age, 52 +/- 16 years) were examined with gadolinium-enhanced PMRA for the evaluation of pulmonary artery (PA) disease. The diagnosis of PAH (ie, systolic PA pressure of > 35 mm Hg) was determined by Doppler echocardiography. The criteria for the diagnosis of chronic PAH by PMRA were dilated central PAs (diameter > 28 mm) and abnormal proximal-to-distal tapering of the PAs. The diagnostic criterion for acute and chronic PE was the presence of an intravascular filling defect. RESULTS: Chronic PAH was present in 18 patients, which was correctly identified by PMRA in 16 patients (sensitivity, 89%). All patients without PAH had normal findings on PMRA (specificity, 100%). Only 1 of 18 patients with normal findings on PMRA showed moderate chronic PAH (negative predictive value, 94%). PAH due to acute/subacute pulmonary thromboembolism (15 patients) was identified in all patients (sensitivity, 100%). Acute PAH was differentiated from chronic PAH in all cases by the detection of intravascular filling defects and the lack of abnormal proximal-to-distal tapering of PAs. CONCLUSIONS: PMRA is a promising noninvasive imaging modality for the identification of patients with acute or chronic PAH. This technique should be considered a sensitive and highly specific screening tool for suspected chronic PAH.

Acute Disease↗

PubMed2000

Comparison of two stent-grafts with different porosity: in vivo studies in a sheep model.

PURPOSE: To compare two stent-grafts with a polyurethane-carbonate (PUC) polymer lining of different pore size and water permeability in the iliac arteries of sheep. MATERIALS AND METHODS: Two stent-grafts with an inner PUC-lining of normal and low water permeability (normal, 1,200 mL/min/cm2; low, 280 mL/min/cm2; pressure gradient, 20 mm Hg) were implanted in each of 16 sheep. Hoop strength was two times higher in low-permeable than in normal-permeable stent-grafts. Patency was monitored with use of angiography and intravascular ultrasound (IVUS) after 1, 3, and 6 months. The sheep were killed after 1 or 6 months. Specimens were studied histologically. IVUS and histologic data were analyzed statistically. RESULTS: IVUS measurements showed a wider patent lumen of the low- compared to the normal-permeable prostheses at all time points (P < .03). This is likely due to the greater hoop strength of the low-permeable stent-graft. After 1 month, both types of prostheses demonstrated complete transprosthetic tissue penetration and were covered with neointima and endothelium. The neointimal area was greater in low- than in normal-permeable stent-grafts (1 month, P < .005; 6 months, P < .03). CONCLUSIONS: Presumably, the higher permeability of the normal-permeable stent-grafts led to the reduced neointimal area by improving transprosthetic capillary ingrowth and endothelialization.

Angiography↗

PubMed2000

Percutaneous treatment of thrombosed primary arteriovenous hemodialysis access fistulae.

BACKGROUND: We reviewed the efficacy of percutaneous intervention in acute thrombotic occlusion of native arteriovenous (AV) fistulae for hemodialysis. METHODS: Eight-one percutaneous procedures were performed in 54 patients presenting with a clotted native dialysis fistula. There were 60 cases of a long-segment thrombosis of the fistula. In 20 cases, a small thrombus usually caused by an underlying severe stenosis was observed. A proximal arterial occlusion was seen in one case. Treatment depended on clot size and included balloon dilation (N = 20), mechanical thrombectomy with various devices (N = 58), as well as pharmacomechanical thrombolysis (N = 3). RESULTS: Full restoration of flow was established in 72 cases (88.9%). Early reobstruction within 14 days occurred in eight cases (11.1%). Primary patency rates after a 1-, 3-, 6-, and 12-month period were 74, 63, 52, and 27%, respectively. Overall fistula patency was 75% after 3 months, 65% after 6 months, 51% after 12 months, and 22% after 24 months. CONCLUSIONS: Acute thrombotic occlusion of native AV fistulae is a major complication of hemodialysis. The results of treatment are believed to be less successful than thrombosis treatment in synthetic grafts. Our results, however, indicate the efficacy of percutaneous treatment in native fistulae, and demonstrate comparable technical results and patency rates.

Adult↗

PubMed2000

[Radial k-scanning for real-time MR imaging of central and peripheral pulmonary vasculature].

PURPOSE: To depict the central and peripheral pulmonary vessel anatomy with real-time radial MR scanning without respiratory control. METHODS: Three healthy volunteers and one patient with pulmonary embolism proven by spiral CT angiography were studied with a 1.5 T MR imaging system. First, a breath-hold, contrast-enhanced MR angiography was performed for comparison of accuracy. Gradient echo images (TR 16 ms, TE 4 ms, flip angle 18 degrees) were obtained applying a combination of radial scanning and the sliding window reconstruction technique. A dedicated back-projector allowed data reconstruction in real-time with a frame rate of 20 images per second. Scanning was performed during free breathing. RESULTS: The described technique depicted the central and peripheral portions of the normal pulmonary anatomy with comparable image quality as the 3D contrast-enhanced angiography. Visualization of the pulmonary emboli as demonstrated by spiral CT was possible. CONCLUSION: Real-time radial scanning allows promising image acquisition of the pulmonary vasculature without respiratory control. Further technical improvements and clinical trials are required to evaluate its role in the diagnosis of vascular pathologies.

Adult↗

PubMed2000

[Aerosolized gadolinium-DTPA for demonstration of pulmonary ventilation in magnetic resonance tomography].

PURPOSE: Magnetic resonance assessment of lung ventilation with aerosolized Gd-DTPA. METHODS: Eleven experimental procedures were carried out in a domestic pig model. The intubated pigs were aerosolized for 30 minutes with an aqueous formulation of Gd-DTPA. The contrast agent aerosol was generated by a small particle aerosol generator. Imaging was performed on a 1.5 T MR imager using a T1-weighted turbo spin echo sequence with respiratory gating (TR 141 ms, TE 8.5 ms, 6 averages, slice thickness 10 mm). Pulmonary signal intensities before and after ventilation were measured in peripheral portions of both lungs. RESULTS: Immediately after ventilation with aerosolized Gd-DTPA, the signal intensity in both lungs increased significantly in all animals with values up to 237% above baseline (mean 139% +/- 48%), but with in some cases considerable regional intra- and interindividual intensity differences. Distinctive parenchymal enhancement was readily visualized in all eleven cases with good spatial resolution. CONCLUSION: The presented data indicate that Gd-DTPA in aerosolized form can be used to demonstrate pulmonary ventilation in large animals with lung volumes comparable to man. Further experimental trials are necessary to improve reproducibility and to define the scope of this method for depicting lung disease.

Aerosols↗

PubMed2000

[Mono-contrast distension study of the small intestine. Comparison of conventional small bowel follow-through with enteroclysis].

PURPOSE: Development of a new monocontrast examination of the small bowel. MATERIAL AND METHODS: The new examination was applied to 20 patients with suspected bowel obstruction or inflammatory bowel disease. A contrast mixture, containing gelatin, a water-soluble contrast medium (Peritrast) and water (GPW-mixture) was given over an intestinal tube. The viscosity of the new contrast mixture was measured by rotation and flow viscosimetry. The diagnostic value and the degree of small bowel distension were determined independently by 3 examiners. By comparison 20 randomized selected small bowel follow-through examinations (SBFT) and 20 small bowel enemas were examined. Special questionnaires were used to determine subjective compatibility and discomfort. RESULTS: Due to the viscosity of the new contrast medium and the administration over an intestinal tube, a good bowel distension was achieved with the GPW mixture. The bowel distension (p: < 0.01) and the diagnostic value (p: < 0.01) of the new examination in comparison to the SBFT was characterized as being significantly better. In comparison to the small bowel enema, distension was not significantly better (p: 0.31-1.0). The diagnostic value of the small bowel enema was characterized as significantly better by one of the three examiners in comparison to the new monocontrast-distenson examination (p-level < 0.01). CONCLUSION: The monocontrast-distension examination is a potential alternative in patients in whom a small bowel enema with barium sulfate is contraindicated.

Abdomen, Acute↗

PubMed2000

Reduction of contrast material dose and artifacts by a saline flush using a double power injector in helical CT of the thorax.

OBJECTIVE: Our objective was to evaluate a combined method of contrast material bolus followed by saline solution flush for thoracic helical CT and statistical comparison with a uniphasic injection protocol. MATERIALS AND METHODS: Fifty patients underwent helical CT of the thorax using 60 ml of contrast material (370 mg I/ml) followed by flushing with 30 ml of physiologic saline solution. These 50 patients had been examined before using our previous protocol, 75 ml of the same contrast material without a subsequent saline solution. Mean attenuation values for both protocols were measured in the superior vena cava, the pulmonary trunk, and the ascending aorta. Image artifacts and mediastinal and hilar depiction were graded and compared. RESULTS: Mean attenuation values in the superior vena cava were considerably higher in the regimen without saline solution flush (459 H versus 352 H) and in the pulmonary trunk and the ascending aorta were almost identical for both protocols. Injection of saline solution diminished surrounding artifacts (p = 0.001). Grading results for the evaluation of mediastinal and hilar structures were not significantly different in the two protocols (p = 0.564). CONCLUSION: Injection of contrast material followed by a saline solution bolus using a double power injector when performing thoracic helical CT allows a 20% reduction of contrast material volume to 60 ml with a similar degree of enhancement. In addition, perivenous artifacts in the superior vena cava are significantly reduced.

Adult↗

PubMed1999

[Hepatic ischaemia during Whipple resection: case report of a rarely required revascularisation].

With the performance of a partial duodenopancreatectomy, the collateral vascular bed between the coeliac trunk and the superior mesenteric artery is reduced. Normally, this does not lead to ischaemia of the upper abdominal organs. However, we present the rare case of a patient in whom a Whipple resection in combination with a hyploplastic coeliac trunk led to hepatic and splenal ischaemia and aorto-hepatic bypass grafting. The indication for preoperative arteriography is in discussion, since variations or alteration of the upper abdominal vessels are known to be common but manifest organ ischaemia during resection is a rare complication. Patients with signs of general arteriosclerosis or those in whom upper abdominal resection has been performed previously may benefit from angiography. In other cases a test occlusion before vessel ligation is considered to be suitable in assessing the need for vascular surgical intervention.

Aorta↗

PubMed1999

[CT-guided percutaneous biopsies for the classification of focal liver lesions: a comparison between 14 G and 18 G puncture biopsy needles].

PURPOSE: Analysis and comparison of CT-guided 14- and 18-gauge cutting needle biopsies to accurately assess focal liver disease. METHODS: The data of 272 CT-guided biopsies in 268 patients were evaluated retrospectively with regard to sensitivity, specificity and complication rate of the chosen needle caliber in differentiating between benign and malignant disease as well as in the ability to determine specific cell types in the various disorders. A 14-gauge (G) needle was used in 101 (37.1%) cases, an 18-g needle biopsy was performed in 171 (62.9%) cases. The Fisher exact test was employed for statistical analysis. RESULTS: Cutting needle biopsy yielded sufficient histologic material in 267 of 272 (98.2%) cases. Correct diagnosis of malignancy was established in 178 of 191 (93.2%) lesions, 73 of 76 (96.1%) disorders were accurately defined as benign, resulting in an overall value of 94.0% (251 of 267). Of these 251 biopsies a definite histological diagnosis could be determined in 90.6% of the cases employing a 14 G needle and in 90.3% using an 18-g needle. The sensitivity, specificity and rate of complications were 94.8%, 92.0%, 3.0% for the 14-g needle and 92.7%, 97.6%, 0.6% for the 18-g needle, respectively. There were no statistically significant differences with regard to the needle size. CONCLUSIONS: CT-guided biopsy of hepatic lesions with the 18-g biopsy needle is of equivalent diagnostic accuracy when compared with the 14-g needle.

Adult↗

PubMed1999

[The Perflex stent, a new balloon-expandable vascular stent: the initial clinical results].

PURPOSE: Clinical evaluation of a newly developed balloon-expandable vascular stent. METHOD: Participating in a multi-center study our clinic enrolled 12 patients with 15 iliac artery stenoses (Fontaine IIa-III) that were treated with the new stent. Three patients had bilateral stenoses. The mean ankle-brachial index (ABI) at rest was 0.76 +/- 0.25 (+/- 1 standard deviation), the mean ABI after exercise was 0.47 +/- 0.20. Indication for stent insertion was a residual trans-lesion pressure gradient > or = 10 mmHg after balloon angioplasty. Follow-up included clinical examination, measurements of the ABI at rest and after exercise, and colour duplex ultrasound (CDS) on the day of hospital dismissal and 1, 6 and 12 months after stent insertion. RESULTS: 16 stents were placed successfully. One stenosis was treated with two stents. Acute complications did not occur. The Fontaine stage increased by at least one stage in all patients. The ABI at rest rose to 0.91 +/- 0.26, the ABI after exercise to 0.86 +/- 0.29. During follow-up one stent occlusion, one stenosis proximal to a stent, and CDS-findings suggesting restenosis in two further stents were observed. CONCLUSIONS: It appears that the Perflex stent may be used in the iliac arteries with a success rate similar to other stents. However, this preliminary result has to be confirmed in a larger series and after a longer follow-up.

Aged↗

PubMed1999

Treatment of hemodialysis-related central venous stenosis or occlusion: results of primary Wallstent placement and follow-up in 50 patients.

PURPOSE: To analyze the effectiveness of stent placement as the primary treatment for central venous obstruction in patients undergoing hemodialysis. MATERIAL AND METHODS: Fifty-seven Wallstents were placed in 50 patients with symptomatic shunt dysfunction and arm swelling due to central venous obstruction. Technical success, complication, and patency rates were evaluated. RESULTS: Stent deployment was successful in all patients, and early rethrombosis (within 1 week) was noted in one patient (2%). Seventy-three episodes of reobstruction occurred and were treated percutaneously with angioplasty alone in 54 cases (74%). Nineteen cases (26%) necessitated additional stent placement. The 3-, 6-, 12-, and 24-month primary patency rates were 92%, 84%, 56%, and 28%, respectively. Cumulative overall stent patency was 97% after 6 and 12 months, 89% after 24 months, and 81% after 36 and 48 months. CONCLUSION: In the treatment of brachiocephalic and subclavian venous obstruction, stent placement shows excellent technical results and helps preserve vascular access for a substantial period. Multiple repeat interventions are, however, frequently required to maintain patency.

Adult↗

PubMed1998

[Novel endoluminal stents for the treatment of arterial fistulas and perforations].

PURPOSE: To evaluate the use of polycarbonate-polyurethane (Corethane) stented grafts for the treatment of arteriovenous fistulas and arterial perforations. MATERIALS AND METHODS: 4 patients at the age of 34 to 81 underwent percutaneous insertion of corethane endoluminal grafts. Two patients had an arterial fistula--one iliaco-iliac, one brachio-brachial. Two patients underwent treatment to seal arterial perforations that occurred in the external iliac artery in one and in a femoral venous bypass in another. RESULTS: In all cases the communication or leakage was sealed by the endograft in place but had to be combined with a detachable balloon in om case. In three patients, a longer follow-up became available, one patient died three weeks after treatment from unrelated causes. While two stent grafts remained open for 15 and 24 months, one patient experienced stent graft occlusion three months after treatment. CONCLUSIONS: Corethane stent grafts are helpful to seal short-neck arteriovenous fistulas and arterial perforations even under emergency conditions.

Adult↗