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Biomedical subjects

J E Wildberger

Publications and source records attributed to J E Wildberger.

At least 19 recordsLinked to original sources
PubMed2001

[Benign metastasizing leiomyoma of the lung--a rare differential diagnosis of pulmonary space-occupying lesions].

HISTORY AND ADMISSION FINDINGS: A 45-year-old woman was refferred for diagnosis of an accidentally found symptomless space-occupying lesions in the central part of the right lung. She had undergone a hysterectomy 4 years before and reported smoking 15 cigarettes daily since the age of 17 years. Physical examination was normal. INVESTIGATIONS: As primary bronchial carcinoma or metastasis to the lung was suspected she underwent a series of diagnostic tests: sonography, computed tomography (CT), gastroscopy, coloscopy, bronchoscopy, skeletal scintigraphy, gynaecological examination and various laboratory tests, none of which indicated a primary extrapulmonary tumour. CT-guided fine-needle biopsy then suggested benign metastasizing pulmonary leiomyoma (BMPL). TREATMENT AND COURSE: The largest of the tumours were surgically removed, confirming BMPL. Hormone receptors (for oestrogen, progesterone) having been demonstrated, progesterone treatment was initiated as prophylaxis against recurrences. CT 6 months later revealed new intrapulmonary foci. Administration of luteinizing hormone-releasing hormone analog to stop completely any oestrogen effect, and CT of the thorax 6 months later showed that both tumour numbers and their size had been reduced. The patient remained asymptomatic and the findings had not changed in the subsequent 12 months. CONCLUSION: BMPL is a rare cause of a space-occupying pulmonary lesion, predominantly affecting middle-aged women after hysterectomy for uterine myoma. The pathogenesis remains unclear, hormone-dependent tumour growth being discussed as a possible mechanism. Anti-oestrogen administration is the treatment of choice to achieve remission and effective prevention of recurrences.

Biopsy↗
PubMed2001

Cross-sectional imaging patterns of desmoplastic fibroma.

The aim of this study was to work out the cross-sectional imaging characteristics of desmoplastic fibroma (DF). In 3 patients with histologically proven DF, the imaging characteristics obtained with cross-sectional techniques were reviewed retrospectively. Radiographs and CT scans were available in all patients, and plain and contrast-enhanced MR examinations in 2 patients. Compared with conventional radiographs, CT allowed more accurate assessment of the extent of bone destruction including cortical breakthrough and articular invasion. Intramedullary tumor growth and soft tissue extension was best detected with MRI. Apart from heterogeneity on MR images, DF displayed nonspecific low signal intensity on unenhanced T1-weighted images and an intermediate to high signal intensity including areas of low intensity on T2-weighted images. Desmoplastic fibroma showed a distinct, inhomogeneous gadolinium enhancement. Although cross-sectional imaging features of DF are nonspecific, some MR characteristics, such as inhomogeneous contrast enhancement and the presence of low-intensity regions on T2-weighted images, are helpful in determining the differential diagnosis. Cross-sectional imaging of DF is useful for local staging of the tumor because it provides valuable information about the extent of bone destruction as well as medullary and extraosseous spread.

Adolescent↗
PubMed2001

Multi-slice CT urography after diuretic injection: initial results.

PURPOSE: To investigate the feasibility of CT urography (CTU) using a multi-slice (MS) scanner and to find out whether a low-dose diuretic injection is advantageous for the opacification of the urinary tract. METHODS: MS-CTU was performed in 21 patients with urologic diseases. In 5/21 patients, 250 ml of physiologic saline Solution were injected. In 16/21 patients, 10 mg of furosemide were injected 3-5 min before contrast material administration. A 4 x 2.5 mm collimation with a pitch of 1.25 and a tube current of 100-150 mA were used. Scan time was 12-16 sec. 3 mm thin axial images with an overlap of 67% were reconstructed. Multiplanar maximum intensity projection (MIP) images were postprocessed to obtain urographic views. Bone structures were eliminated using the volume-of-interest method. RESULTS: Furosemide-enhanced MS-CTU achieved either near complete or complete opacification in 30/32 (94%) ureters and in 32/32 (100%) pelvicaliceal systems up to a serum creatinine of 150 mumol/l. In our series, only one CTU scan per patient was needed to obtain a diagnostic urogram after 10 min of contrast material injection. Ureteral compression was not necessary. When physiologic saline solution was used instead of furosemide, the radiopacity inside the enhanced pelvicalices was 4-5 times higher and more inhomogeneous. Diuretic-enhanced MS-CTU was more accurate in the depiction of pelvicaliceal details. In combination with furosemide, calculi were well identified inside the opacified urine and were safely differentiated from phleboliths. Postprocessing times of up to 20 minutes were problematic as were contrast-enhanced superimposing bowel loops on MIP images. CONCLUSION: Preliminary results demonstrate a good feasibility of furosemide-enhanced MS-CTU for obtaining detailed visualization of the entire upper urinary tract.

Adult↗
PubMed2001

Multi-slice CT for visualization of pulmonary embolism using perfusion weighted color maps.

PURPOSE: The purpose of our preliminary study was to evaluate the feasibility of a new technique for the perfusion weighted color display of the density of lung parenchyma derived from multi-slice CT (MSCT) data sets of clinical routine examinations for visualization of pulmonary embolism (PE). MATERIALS AND METHODS: Imaging of patients with suspected PE was performed on a commercially available MSCT (Somatom Volume Zoom; Siemens, Forchheim, Germany) after intravenous application of 120 cc of contrast-medium using a power injector. Scan parameters were 140 kV and 100 mAs, using a thin collimation of 4 x 1 mm and a table speed of 7 mm (pitch: 1.75). Derived from thin collimation axial slices (slice thicknesseff. 1.25 mm, reconstruction increment 0.8 mm), a new image processing technique was deployed. Based on these source images, an automated 3D-segmentation of the lungs was performed followed by threshold based extraction of major airways and vascular structures. The filtered volume data were color encoded and finally overlayed onto the original CT images. This color encoded display of parenchymal density distribution of the lungs was shown in axial, coronal and sagittal plane orientation. In four patients with excluded PE as well as in two patients with proven PE this new technique was performed. RESULTS: In the four patients that were considered negative regarding PE on MSCT, lung densitometry showed a homogeneous distribution of color encoded densities without circumscribed decreased or increased areas, beside the usually present gravity-dependent gradient in ventro-dorsal direction. In the two patients with proven PE, low density values on perfusion weighted color maps were found distally to the occluded pulmonary arteries. CONCLUSIONS: Our initial experience indicates that lung densitometry with an optimized display of the density distribution within the lung parenchyma may provide additional information in patients with suspected or proven PE. However, a comparison with ventilation/perfusion scintigraphy and a larger number of patients are necessary for the full clinical evaluation of this new functional imaging methodology.

Aged↗
PubMed2001

[The influence of motion artifacts conditioned by reconstruction, on the coronary calcium score in multislice spiral CT].

UNLABELLED: The influence of motion artifacts conditioned by reconstruction, on the coronary calcium score in multislice spiral CT. PURPOSE: A major problem of the quantification of coronary calcifications is a high variability of the coronary calcium score between recurrent examinations and different observers. Aim of our study is to evaluate the influence of different RR-intervals on the coronary calcium score utilizing retrospectively gated Multislice Spiral CT (MSCT) data sets. MATERIALS AND METHOD: 50 consecutive patients underwent MSCT examination (Somatom Volume Zoom, Siemens, Forchheim, G) utilizing a standardized scan protocol (4 x 2.5 mm collimation, 3 mm increment, tube current 133 mAs, tube voltage 120 kV). Retrospectively gated image reconstruction was performed every 10 % of the RR interval. Coronary calcification was evaluated by the Agatston score. Coronary risk assessment was performed in all patients with image reconstruction beginning at 80 % of the RR interval. The reconstruction intervals with the least motion artifacts were identified and chosen as reference for a reevaluation of the coronary risk. The results of different reconstruction times were compared. RESULTS: The mean calcium score was 551.6. The calcium score varied between 512.2 (90 %) and 571.7 (70 %), depending on the image reconstruction interval. Compared to the mean calcium score a new classification of the coronary risk was necessary in 7/50 of the patients at 80 % reconstruction interval, and in 2/50 of the patients at 50 % of the RR interval, respectively. CONCLUSION: Movement of the coronary arteries at different image reconstruction intervals has an important influence on the coronary calcium score. Based on our data, we propose image reconstruction at 50 % of the RR interval for evaluation of the coronary calcium score by MSCT.

Adult↗
PubMed2001

Navi-ball: a new guidance device for CT-directed punctures.

RATIONALE AND OBJECTIVES: A new navigation system (Navi-Ball) for computed tomography (CT)-guided punctures was tested clinically. METHODS: The device consists of a transparent hemisphere with an angular scale. The hemisphere is fluid filled and contains a bubble indicating the angulation. The system works as a circular spirit level. Adapted to the handle of the needle, it allows needle adjustment according to the planned puncture path on the CT image. The system was tested in 36 patients who had 40 procedures. The needle deviation (in relation to the planned course of the needle) was measured in two rectangular planes. RESULTS: Without requiring preparation time, the guidance system allowed rapid and easy performance of the puncture. First-time needle placement in a double-angulated approach led to a deviation of the needle from the planned path ranging from 0.2 degrees to 4.6 degrees (mean 2.1 degrees, SD 1.4 degrees ) in the axial plane and from 0.4 degrees to 4.0 degrees (mean 2.3 degrees, SD 1.2 degrees). CONCLUSIONS: This "low-tech" system offers easy to use guidance by a single operator and provides for adequate accuracy of first-time needle placement.

Equipment Design↗
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↗
PubMed2000

Potential of a new laser target system for percutaneous CT-guided nerve blocks: technical note.

A prototype of a laser target device was used for CT-guided nerve blocks in a preliminary series of nine interventions. The system provides guidance from any possible approach. High accuracy of needle insertion was achieved; the average deviation of the planned from the actual angle was 1.4 degrees. The target device is valuable for facilitating minimally invasive therapy and can decrease the time required for the procedure.

Adult↗
PubMed2000

Diagnostic and therapeutic management of lumbar and thoracic spondylodiscitis--an evaluation of 59 cases.

Fifty-nine patients with spondylodiscitis (SD) of the thoracic and/or lumbar spine were followed-up clinically and radiologically [X-ray, computed tomography (CT), magnetic resonance imaging (MRI)] over a mean time of 2.2 years (1-6.5 years). All patients without abscess formation (n = 35) were treated conservatively. Out of the group with abscess formation (n = 24) 6 patients were also treated conservatively, 11 were drained under CT control and 7 were operated. At time of diagnosis, "signs of florid inflammation" were seen in 60% of the roentgenograms, in 93% of the CTs and in all of the MRls. The sensitivity to differentiate between SD with and without abscess formation was 85% by MRI and 69% by CT. "Signs of regressive inflammation" and "signs of increasing osseous consolidation", essential facts for starting remobilization, could first be seen using CT 6 weeks after onset of therapy. Using MRI these signs were seen with a considerable delay at 12 weeks. Clinically, only 3 of the 59 analyzed patients developed recurrent SD. In conclusion, MRI is the radiological method of choice for establishing the diagnosis of SD, in particular with regard to differentiating between cases with and without abscess formations. In contrast, CT is superior for performing success control after treatment. Therapeutically, conservative, minimal-invasive and operative procedures are not rival but rather complementary.

Abscess↗
PubMed2000

Recanalization of thrombosed dialysis access with use of a rotating mini-pigtail catheter: follow-up study.

PURPOSE: To evaluate the feasibility, efficacy, and safety of mechanical thrombectomy of occluded dialysis access with use of a rotating mini-pigtail catheter. MATERIALS AND METHODS: Thrombus was fragmented by mechanical action of the rotating pigtail tip (5-mm diameter), while the guide wire exited a sidehole at the pigtail curvature and served as a fixed rotation axis. Twenty-six procedures were performed in 22 patients (12 men, 10 women; mean age, 55.5 years). Native fistulas were treated in 15 instances, polytetrafluoroethylene (PTFE) grafts were treated in 11 instances. Average occlusion time was 20 hours +/- 13 (range, 5-46 hours), average occlusion length was 25.6 cm +/- 10.1 (range, 6-45 cm). Thrombus fragmentation was followed by balloon angioplasty of underlying stenoses. RESULTS: In all 26 procedures, the dialysis access was successfully declotted with subsequent dialysis using the access (clinical success rate, 100%). Handling of the mini-pigtail catheter was simple and rapid, regardless of whether a graft or a native fistula was treated. Average duration of the intervention was 118 minutes +/- 30. Mean primary patency was 165 days +/- 167. Primary patency rate was 82% at 30 days, 65% at 3 months, and 47% at 6 months. There was no evidence of complications due to the thrombus fragmentation procedure. CONCLUSION: The results suggest that declotting of occluded dialysis grafts and fistulas with the mini-pigtail catheter is as effective and safe as other more established percutaneous therapies. It may serve as an easy-to-handle, low-budget alternative to current thrombectomy devices.

Adult↗
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

[Initial experiences with a new optical target system (SimpliCT) for CT-guided punctures].

PURPOSE: To evaluate the prototype of a new optical target device for CT-guided punctures and interventions. METHODS: An optical target device for CT-guided punctures was applied in 24 interventions. The system consists of a laser target device mounted on a stand. The biopsy needle is adjusted according the course of a laser beam. The target angle has to be adjusted on the laser unit. The laser carrier can be moved along an 90 degrees-angled rail, allowing punctures from any angle in plane. Furthermore, angulation in the z-plane is possible, supporting interventions with gantry tilt. Size and depth of the target lesions, the planned and the actual angle of the inserted needle, the numbers of corrections of the needle position, and the time required for the puncture were evaluated. The user rated the benefit of the system and the ease of the application. RESULTS: All 24 interventions were carried out successfully. The mean difference between the planned and the actual angle of the needle was 1.3 degrees (SD: 0.7 degree). The system was considered as easy to handle and as a valuable aid. CONCLUSIONS: The laser target device is a simple navigation system which allows accurate positioning of a needle. Requiring an acceptable low preparation time, it easily can be integrated into the procedure.

Adult↗
PubMed2000

[Percutaneous transjugular thrombectomy in iliocaval thrombosis-- initial experience with a newly developed 12F balloon sheath].

PURPOSE: To evaluate the feasibility of percutaneous thrombectomy for the removal of floating iliocaval thrombi using a balloon sheath. MATERIALS AND METHODS: A newly developed balloon sheath (inner diameter: 12-F; outer diameter: 18-F) was tested in two patients with extensive iliocaval thrombosis. Mechanical thrombectomy was performed due to recurrent pulmonary embolism under therapeutic anticoagulation in antiphospholipid-antibody syndrome and, respectively, paraneoplastic thrombosis without a decrease of fresh thrombus mass in spite of pharmacological treatment. Via a transjugular access (20-F), the sheath was advanced retrogradely into the inferior vena cava. After blocking of the vessel, mechanical fragmentation was performed through the working channel coaxially, using a temporary vena cava filter as a rotating basket (max. diameter: 30 mm). Residual thrombus fragments were removed by aspiration. RESULTS: The thrombectomy balloon sheath tested allowed a complete removal of fresh thrombi after fragmentation. In addition, older clot material was obtained. Balloon occlusion prevented the central embolization of thrombus fragments. Clinical signs indicating pulmonary embolism were not seen. The fluid loss due to aspiration was negligible. CONCLUSIONS: The newly developed 12-F balloon sheath proved to be efficient for the extraction of large thrombi. Balloon occlusion safely prevented central embolization of thrombus fragments proximal to the sheath.

Aged↗
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

[Papillary renal cell carcinoma: comparison of CT and gross morphology].

OBJECTIVE: To analyze the CT appearance of papillary renal cell tumor (pRCT) under consideration of gross pathology. MATERIAL AND METHODS: Preoperative CT-scans of 10 patients suffering from pRCT were re-evaluated by two experienced radiologists. CT appearance was correlated to gross morphology. RESULTS: On CT, 9/10 tumors were depicted as rounded, well circumscribed and sharply delineated masses. These tumors presented a hypodense central area correlating to necrosis in gross pathology. The central area of necrosis was surrounded by vital tumor tissue, presenting as a serpiginous, contrast-enhancing margin on CT. One tumor was polycyclic due to multiple tumor nodules, but sharply demarcated towards the surrounding renal tissue. CONCLUSIONS: pRCT presents a quite unique CT appearance similar to its gross pathology.

Adult↗