Biomedical subjects

Jürgen Biederer

Publications and source records attributed to Jürgen Biederer.

10 recordsLinked to original sources

PubMed2006

Reproducibility of computer-aided volumetry of artificial small pulmonary nodules in ex vivo porcine lungs.

OBJECTIVE: The main purpose of this study was to investigate the reproducibility of computed tomography (CT)-based volumetric measurements of small pulmonary nodules. METHODS: We implanted 70 artificial pulmonary nodules in 5 ex vivo porcine lungs in a dedicated chest phantom. The lungs were scanned 5 times consecutively with multislice-CT (collimation 16 x 0.75 mm, slice thickness 1 mm, reconstruction increment 0.7 mm). A commercial software package was used for lesion volumetry. The authors differentiated between intrascan reproducibility, interscan reproducibility, and results from semiautomatic and postprocessed volumetry. RESULTS: Analysis of intrascan reproducibility revealed a mean variation coefficient of 6.2% for semiautomatic volumetry and of 0.7% for human adapted volumetry. For interscan reproducibility a mean variation coefficient of 9.2% and for human adapted volumetry a mean of 3.7% was detected. CONCLUSION: The presented volumetry software showed a high reproducibility that can be expected to detect nodule growth with a high degree of certainty.

Analysis of Variance↗

PubMed2006

Treatment of acute pulmonary embolism: local effects of three hydrodynamic thrombectomy devices in an ex vivo porcine model.

PURPOSE: To report an ex vivo study on the local effects of hydrodynamic thrombectomy for the treatment of acute pulmonary embolism (off-label use). METHODS: Three devices (6-F AngioJet Xpeedior and 6-F and 8-F Oasis) were used for hydrodynamic thrombectomy inside the arteries of 24 inflated and perfused porcine lung explants. Each system was used at multiple positions inside 4 intact and 4 embolized lungs in vessels measuring 2 to 4 mm, 4 to 6 mm, 6 to 8 mm, and 8 to 10 mm. Angiograms prior to, during, and after catheter positioning and system operation were used to detect arterial wall trauma and to measure local clot removal per 30-second cycle. A total of 21 vessel wall samples were subjected to scanning electron microscopy (SEM) to evaluate non-perforating lesions. RESULTS: All systems were able to remove clot material. The average recanalized vessel length normalized to 30 seconds for vessel diameters of 2 to 4 and 8 to 10 mm, respectively, was 1.17 and 1.75 cm (AngioJet), 0.97 and 0.25 cm (6-F Oasis), and 2.2 and 1.05 cm (8-F Oasis). Perforations occurred during positioning of the 6-F Oasis (4/78 maneuvers) and 8-F Oasis (13/60), but not the AngioJet (0/89); perforations were also seen during system operation (AngioJet: 21/89 activations, 6-F Oasis: 4/78, and 8-F Oasis: 9/60; all lesions inside vessels <6 mm in diameter). SEM showed 35 lesions, 14 with perforation (contrast extravasation) and 21 without perforation (induced by the tip of the guidewire). CONCLUSION: The AngioJet was most efficient in clot removal, followed by the 8-F Oasis. The 6-F Oasis was least efficient, but had fewest complications. According to these experiments, the tested hydrodynamic thrombectomy devices may cause perforations in vessels <6 mm in diameter. Changes in catheter design to reduce system-specific complication rates or to improve the efficacy of clot removal are warranted.

Acute Disease↗

PubMed2005

[Magnetic resonance imaging: technical aspects and recent developments].

Magnetic resonance imaging (MR) is based on electromagnetic effects of rotating protons in hydrogen of water and organic materials. With a magnetic field and high frequency electromagnetic pulses, MRI generates data sets to be reconstructed as two-dimensional cross-sectional images or three-dimensional volumes of anatomic structures with excellent soft-tissue contrast. Since modern MR techniques have dramatically reduced acquisition times and motion artifacts, breathhold studies of moving organs such as the stomach and intestinum or heart and lung have become part of the daily routine. MRI does not apply ionizing radiation, therefore dynamic studies and repeated controls may be performed. Original contraindications such as metallic implants or electronic devices (pacemakers) have become relative in many cases. Since MR contrast media are considered not nephrotoxic when applied in regular dose, MRI provides a most valuable alter native for imaging studies and angiography in patients with renal insufficiency. The recent developments in the field of internal medicine include functional imaging of stomach, intestinum, heart and lung. Based on these experiences, protocols for whole-body MRI within reasonable acquisition time and at acceptable costs have been developed. In particular for screening and staging, such MRI proto cols might cover an even broader spectrum of applications in the near future. Based on the knowledge of recent trends and technical backgrounds, many perspectives are opened up for the further development of the method in interdisciplinary cooperation.

Brain↗

PubMed2004

CT-guided lymphoscintigraphy in patients with squamous cell carcinoma of the head and neck: a feasibility study.

Accurate knowledge of lymphatic drainage facilitates planning of surgery for patients with squamous cell carcinoma of the head and neck. The aim of this study was to evaluate the feasibility of a new injection technique for lymph node detection in patients with squamous cell carcinoma of the hypopharynx and larynx, in whom simple peritumoural injection is hampered by the tumour localisation. Computed tomography (CT)-guided lymphoscintigraphy was performed in a total of 13 patients with squamous cell carcinoma of the hypopharynx and larynx who could not be injected by simple visual inspection. In a first step, contrast medium-enhanced axial 5-mm-thick CT slices of the neck were obtained. After tumour localisation on these CT images, 1-2 ml contrast medium and, in the event of appropriate distribution, subsequently 50 MBq technetium-99m colloid were injected at one to three peritumoural sites under CT guidance. Peritumoural tracer distribution was controlled by thin-slice CT. Subsequently, planar scintigrams from anterior, right and left lateral views were obtained. In all patients, peritumoural colloid application was feasible, as shown on control CT scans. Post injection, neither severe nor minor complications were noted. The patients complained of only low pain sensations with an average score of 1.8 on a pain scale from 0 to 10. Lymphatic drainage was identified in nine of the 13 patients, with a total of 14 detected lymph nodes. In six patients, ipsilateral sentinel lymph nodes were visualised; bilateral sentinel lymph nodes were identified in one patient and contralateral lymphatic drainage was observed in two patients. CT-guided lymphoscintigraphy is a feasible and minimally invasive diagnostic tool for sentinel lymph node detection in patients with squamous cell carcinoma of the hypopharynx and the larynx. In contrast to endoscopic colloid injection under general anaesthesia, this technique seems to be a well-tolerated method for lymphatic mapping prior to surgical procedures.

Adult↗

PubMed2004

Volumetric interpolated contrast-enhanced MRA for the diagnosis of pulmonary embolism in an ex vivo system.

PURPOSE: To implement a three-dimensional gradient-recalled echo (GRE) volumetric interpolated breath-hold examination (VIBE) sequence for pulmonary contrast-enhanced MRA (CE-MRA) in an experimental setup. MATERIALS AND METHODS: Eight porcine lungs were intubated, inflated inside a chest phantom, and examined at 1.5 T during slow perfusion (2-300 mL/minute). Three-dimensional-MRA was performed with and without contrast agent using three-dimensional-GRE (VIBE) with TR/TE = 4.5/1.9 msec, TA = 23 seconds, FOV = 390 mm, FA = 12 degrees /30 degrees, as well as a standard three-dimensional-GRE sequence and T2 fast spin-echo (FSE) sequences. Four of the eight lungs were embolized with autologous blood clots. By consensus readings, two observers evaluated the detectability of peripheral vessels, signal intensity over vessels and lung, and visualization of emboli. Digital subtraction angiograms served as a control to document vessel patency. RESULTS: Prior to contrast administration, three-dimensional-VIBE/12 degrees yielded the best results for lung parenchyma signal and visualization of small vessels (third-order, P < 0.01); however, no emboli were detected (due to lack of contrast). After administration of contrast agent, three-dimensional-GRE (VIBE) at FA = 30 degrees provided significantly better results (fifth-order branches, documentation of subsegmental occlusions [fourth order], P < 0.01). T2-FSE images documented water uptake into the lungs. Digitally subtracted angiography (DSA) confirmed the patency of seventh-order branches. CONCLUSION: This ex vivo study confirms the potential advantages of using a dual MR investigation for pulmonary embolism, combining three-dimensional-GRE (VIBE) at FA = 12 degrees to image lung parenchyma and at FA = 30 degrees for CE-MRA..

Angiography, Digital Subtraction↗

PubMed2003

Simulated pulmonary nodules implanted in a dedicated porcine chest phantom: sensitivity of MR imaging for detection.

PURPOSE: To evaluate the diagnostic accuracy of common magnetic resonance (MR) imaging sequences for detection of small pulmonary nodules by using a chest phantom and porcine lungs containing simulated lesions. MATERIALS AND METHODS: Fourteen porcine lungs containing 366 porcine myocardial tissue implants were inflated inside a phantom. Two-dimensional (2D) and three-dimensional (3D) gradient-echo (GRE), T2-weighted turbo spin-echo (SE), and T2-weighted single-shot SE train MR sequences were performed. Spiral computed tomography (CT) was performed for comparison. Blinded observers read the images and recorded the sizes and locations of visible nodules by consensus. The sensitivity of each imaging method for depicting single nodules of given sizes was calculated. Specificities, positive predictive values (PPVs), and negative predictive values (NPVs) for detection of one or more nodules of various sizes were calculated. RESULTS: Sensitivities of 3D GRE, 2D GRE, T2-weighted turbo SE, and T2-weighted single-shot SE train MR imaging and of CT were 0.50, 0.40, 0.12, 0.00, and 0.55, respectively, for detection of 1.4-mm nodules and 0.88, 0.84, 0.69, 0.06, and 0.96, respectively, for detection of 4.2-mm nodules. The 95% CIs for CT and GRE MR imaging overlapped, but those for turbo SE and single-shot SE train MR imaging differed significantly (P <.05). For detection of nodules larger than 5 mm, all examinations except single-shot SE train MR imaging yielded a specificity, PPV, and NPV of 1.00 each. For detection of nodules smaller than 5 mm, diagnostic accuracy of 3D GRE MR imaging was high: Specificity, PPV, and NPV all were approximately 0.90. Two-dimensional GRE MR imaging results were influenced by false-positive findings: Specificity was 0.64; PPV, 0.74; and NPV, 1.00. CONCLUSION: Common MR imaging sequences such as 3D GRE have high diagnostic accuracy in depicting small pulmonary nodules when artifacts from cardiac and respiratory motion are absent.

Animals↗

PubMed2003

Interstitial lung disease in polymyositis and dermatomyositis: clinical course and response to treatment.

OBJECTIVES: To assess the prevalence, clinical characteristics, and treatment options of patients with interstitial lung disease (ILD) in polymyositis and dermatomyositis (PM/DM). PATIENTS AND METHODS: Sixty-three consecutive patients with PM/DM underwent standardized screening. Patients with ILD were monitored prospectively, and graded immunosuppression was administered according to the rate of clinical progression. RESULTS: ILD was diagnosed in 20 of 63 patients (32%). Generally, the clinical and serologic findings of the anti-Jo1 syndrome were present. Follow-up evaluation disclosed either a progressive or a nonprogressive course. The 10 patients with progressive ILD were distinguished from the nonprogressive group by extensive ground-glass opacities on high-resolution computed tomography (HRCT) and by bronchoalveolar lavage (BAL) neutrophilia. Intravenous pulse cyclophosphamide prevented further progression in all 10 patients and led to some functional improvement. In the 10 patients without rapidly progressive lung disease, immunosuppression of moderate intensity stabilized pulmonary findings during a median 35 months of follow-up. CONCLUSIONS: The prevalence of ILD in our patients with PM/DM was 32%; this emphasizes the need for pulmonary screening in all PM/DM patients. Progressive disease, featuring ground-glass opacities on HRCT and an inflammatory BAL cell profile, is amenable to intensive immunosuppression. Conversely, patients who do not have these HRCT and BAL features appear to have a low risk of pulmonary deterioration. RELEVANCE: Because the treatment for ILD seems to depend on the rate of clinical progression, future therapeutic trials of lung disease in PM/DM should stratify patients accordingly.

Adult↗

PubMed2003

Artificial thorax for MR imaging studies in porcine heart-lung preparations.

A double-walled magnetic resonance (MR) imaging-compatible container with a flexible diaphragm was designed to hold freshly excised porcine heart-lung preparations. The saline contents simulate MR signal of an actual chest wall. Continuous evacuation keeps the lung inflated. A variety of experiments with different imaging modalities, including angiography, under close to in vivo conditions are feasible. Access to bronchial system and lung vessels allows for various studies.

Animals↗

PubMed2003

Lung morphology: fast MR imaging assessment with a volumetric interpolated breath-hold technique: initial experience with patients.

PURPOSE: To prospectively evaluate the clinical feasibility of magnetic resonance (MR) imaging of the lungs with fast volumetric interpolated three-dimensional (3D) gradient-recalled-echo (GRE) sequences and to compare this examination with standard computed tomography (CT) in patients with lung abnormalities. MATERIALS AND METHODS: Twenty-five patients with different lung abnormalities were examined with 3D GRE MR imaging. The small pulmonary nodules in seven, TNM stage of large intrapulmonary tumors in eight, and benign bronchial disease in five patients were evaluated. MR imaging-based diagnoses were compared with diagnoses made at CT and at discharge from the hospital. Contingency tables and the McNemar test were used to evaluate the significance of differences between MR imaging- and CT-based diagnoses. RESULTS: The MR imaging- and CT-based diagnoses were identical in 24 of 25 patients. In the remaining patient, clinical findings confirmed the accuracy of the MR imaging finding of pleural empyema. Ten of 15 solid pulmonary nodules smaller than 10 mm in diameter were detected at MR imaging (P >.1). Tumor stages at MR imaging and CT were identical, but lymph node stages at the two examinations differed in two of eight patients owing to overestimation of lymph node size at MR imaging (P >.2). In the five patients with bronchiectasis, MR imaging depicted 26 of 33 affected lung segments; differences between MR imaging and CT findings of bronchial dilatation (P >.05) and bronchial wall thickening (P >.2) were not significant. Peribronchial fibrosis was overestimated at MR imaging owing to image artifacts (P <.05). CONCLUSION: Study results confirmed the feasibility of fast breath-hold 3D GRE MR imaging of the lung.

Adolescent↗

PubMed2003

Suspected pulmonary artery disruption after transvenous pulmonary embolectomy using a hydrodynamic thrombectomy device: clinical case and experimental study on porcine lung explants.

PURPOSE: To use porcine lung explants for reconstructing possible situations in which a vessel wall disruption might have occurred in a patient suffering fatal hemoptysis after pulmonary embolectomy with a hydrodynamic thrombectomy device. METHODS: A 76-year-old woman with massive pulmonary embolism underwent transvenous pulmonary embolectomy using a 6-F AngioJet Xpeedior catheter according to manufacturer's instructions. While activating the device in the middle lobe artery (approximately 8 mm diameter), massive and ultimately fatal arterial bleeding occurred through the tracheal tube. Because no autopsy was authorized, an experimental study was designed to examine possible causes for the vessel disruption. Five fresh porcine heart-lung preparations were examined inside a dedicated chest phantom. Access to the pulmonary vessels was provided through catheters inside the right and left ventricular outlets. A low-flow circulation was maintained with an external pump. The 6-F AngioJet thrombectomy device was activated at 42 sites inside vessels from 2 to 10 mm in diameter; in one lung, 8 activations were made after deliberately withdrawing the guidewire. RESULTS: Vessels >6 mm in diameter remained intact. Vessel wall disruption occurred in 4 of 7 vessels between 4 and 6 mm in diameter and in 13 of 14 segmental arteries <4 mm in diameter (regardless of whether or not a guidewire was used). The signs of vessel wall disruption included extravasation of contrast material, arteriovenous fistula, and laceration of distal airspaces with contrast inside the bronchus. CONCLUSIONS: The application of this system has to be considered potentially dangerous when activated inside vessels with diameters <6 mm. The use of this device appears to be safe only inside main branches of the lung vessels at this time. Additional experiments will be required to substantiate these initial results.

Aged↗