Biomedical subjects

M Thelen

Publications and source records attributed to M Thelen.

At least 73 records · Page 4Linked to original sources

PubMed2001

Lack of mutagenic and co-mutagenic effects of magnetic fields during magnetic resonance imaging.

Mutagenic and co-mutagenic effects of static, pulsed bipolar gradient, and high-frequency magnetic fields, as well as combinations of them, were examined using the Ames test. The Ames test using Salmonella typhimurium bacteria, wild-type strain RTA, preincubation assay, without metabolic activation, was performed. All combinations of magnetic fields were tested with and without co-exposure to N-methyl-N'-nitro-N-nitrosoguanidine and benzo[a]pyrene-4,5-oxide, ethylene oxide, carboplatin, or cisplatin. As expected, chemical mutagens caused a clear-cut increase of the revertants in the Ames test. However, neither the static fields nor a combination of a static magnetic field with the time-varying bipolar gradient field or a pulsed high-frequency magnetic field caused an alteration in the number of revertants in the Ames test. No co-mutagenic effect of any magnetic field combination was observed. In conclusion, magnetic fields used during clinical magnetic resonance imaging (MRI) were neither mutagenic nor co-mutagenic.

Animals↗

PubMed2001

Dynamic (19)F-MRI of pulmonary ventilation using sulfur hexafluoride (SF(6)) gas.

A new method for dynamic imaging of pulmonary wash-in and wash-out kinetics of inhaled sulfur hexafluoride (SF(6)) gas was developed. Measurements at the fluorine-19 Larmor frequency were performed in pigs using a gradient echo pulse sequence with 0.5 ms echo time and a measurement time of 9.1 s per image. Dynamic MRI was performed during wash-in and wash-out of SF(6) gas in mechanically ventilated porcine lungs. A postprocessing strategy was developed for quantitative determination of wash-out time constants in the presence of noise. Mean wash-out constants were 4.78 +/- 0.48 breaths vs. 4.33 +/- 0.76 breaths for left and right lung when ventilation was performed with low tidal volume, and 1.73 +/- 0.16 breaths vs. 1.85 +/- 0.11 breaths with high tidal volume ventilation. In conclusion, breath-hold MRI of SF(6) gas is feasible in large animals. Moreover, regional wash-in and wash-out kinetics of SF(6) can be determined noninvasively with this new method. Potential human applications are discussed. Magn Reson Med 45:605-613, 2001.

Animals↗

PubMed2001

[Chronic radiation effects on dental hard tissue (radiation caries). Classification and therapeutic strategies].

OBJECTIVES: Since the first description of rapid destruction of dental hard tissues following head and neck radiotherapy 80 years ago, "radiation caries" is an established clinical finding. The internationally accepted clinical evaluation score RTOG/EORTC however is lacking a classification of this frequent radiogenic alteration. MATERIAL AND METHODS: Medical records, data and images of radiation effects on the teeth of more than 1,500 patients, who underwent periradiotherapeutic care, were analyzed. Macroscopic alterations regarding the grade of late lesions of tooth crowns were used for a classification into 4 grades according to the RTOG/EORTC guidelines. RESULTS: No early radiation effects were found by macroscopic inspection. In the first 90 days following radiotherapy 1/3 of the patients complained of reversible hypersensitivity, which may be related to a temporary hyperemia of the pulp. It was possible to classify radiation caries as a late radiation effect on a graded scale as known from RTOG/EORTC for other organ systems. This is a prerequisite for the integration of radiation caries into the international nomenclature of the RTOG/EORTC classification. CONCLUSIONS: The documentation of early radiation effects on dental hard tissues seems to be neglectable. On the other hand the documentation of Late radiation effects has a high clinical impact. The identification of an initial lesion at the high-risk areas of the neck and incisal part of the tooth can lead to a successful therapy as a major prerequisite for orofacial rehabilitation. An internationally standardized documentation is a basis for the evaluation of the side effects of radiooncotic therapy as well as the effectiveness of protective and supportive procedures.

Adult↗

PubMed2001

[Diagnosis of acute lung embolism with spiral CT and 3D reconstruction. Development of an animal model and technical probe in an ex-vivo experiment].

PURPOSE: To develop a model for simulation the CT morphologic situation of acute pulmonary embolism, to evaluate the accuracy of spiral CT and 3D reconstruction in the detection of artificial emboli and to investigate the influence of the orientation of emboli depending on z-axis orientation. MATERIALS AND METHODS: Standardized artificial emboli made of wax and of defined size and shape were positioned into the pulmonary arteries of porcine lungs. Castings of the embolized pulmonary arterial trees were made by injection of a special opaque resin. After performance of spiral CT the data sets of the emboli and the pulmonary arteries were post-processed. The 3D segmentations were compared with the anatomic preparation to evaluate the accuracy of spiral CT/3D reconstruction-technique. Technical specimens simulating CT-morphology of acute embolized vessels underwent spiral CT in six different positions with respect to the z-axis. The CT data were reconstructed using a standardized and a contrastadapted method with interactive correction. The 3D emboli were analysed under qualitative aspects, and measurements of their extent were done. RESULTS: In nearly 91%, there was complete agreement between CT and the corresponding findings at the anatomical preparation. Measurements of the 3D reconstructed technical specimens showed discrepancies of shape and size in dependence of the size of the original preparation, orientation and reconstruction technique. Overestimation up to 4 mm and underestimation to 2.2 mm were observed. Measurements of preparations with heights from 14 to 26 mm showed variances of +/- 1.5 mm (approximately 6-11%). CONCLUSION: The presented models are suitable to simulate CT morphology of acute pulmonary embolism under ex-vivo conditions. Accuracy in the detection of artificial emboli using spiral CT/3D reconstruction is affected by localization, size and orientation of the emboli and the reconstruction technique.

Acute Disease↗

PubMed2001

[Multi-rotation CT and acute respiratory distress syndrome. Animal experiment studies].

PURPOSE: Aim of the study was to investigate alveolar inspiration and expiration using multiscan CT. Results of a visual assessment using a scoring system were compared with density ranges known to represent alveolar ventilation best. METHOD: Pigs were examined before and after lavage-induced ARDS. All animals were examined using dynamic multiscan CT. The visual assessment was done by a scoring system proposed by Gattinoni. The results were compared with planimetric determination of defined density ranges. RESULTS: In the healthy lung, the visual analysis showed higher scores at lower airway pressures with a marked gradient, whereas at higher pressures neither opacities nor gradients were observed. In ARDS-lungs, the scores were double as high as in healthy lungs at low pressures. At the same time the differences between inspiration and expiration were minor. There was good correlation between lung density measurements and lung opacities under different airway pressures. In healthy lungs, the greatest area increase is found between -910 and -700 HU. The biggest area growth in the ARDS-model is observed between -910 and -300 HU. CONCLUSION: Dynamic multiscan CT allows for determining different ventilation-relevant lung compartments and lung density ranges.

Animals↗

PubMed2001

Paired inspiratory/expiratory spiral CT and continuous respiration cine CT in the diagnosis of tracheal instability.

In tracheo- and bronchomalacia, localisation and determination of collapse is necessary for planning of surgical procedure. We compared inspiratory and expiratory spiral CT, cine CT, bronchoscopy, exemplary cine MR, and evaluated the clinical relevance. Twenty-nine patients (2 follow-ups; mean age 61 years, age range 27-85 years) with suspected or verified tracheal stenosis or collapse (post-tracheotomy: n = 17; neoplasm: n = 5; other: n = 7) underwent paired breath-hold inspiratory and expiratory spiral CT. Forty-five additional cine CT were performed at 1-4 levels (mean 1.5) during continuous respiration (increment 100 ms) to clarify respiratory collapse. The tracheal cross-sectional diameters of both techniques were calculated. Comparison with bronchoscopy, follow-up, and influence upon therapy were evaluated retrospectively. Exemplary comparison with cine MR (8 frames/s) was done in 3 cases. In addition to bronchoscopy, further information concerning localisation, extent, collapse, stability of the tracheal wall, distal portions of the stenosis and extraluminal compressions were obtained. A significantly higher degree and more pathological collapses (> 50%) were seen using cine CT (38%) compared with paired spiral CT (13%; degree: p < 0.0001; number: p < 0.001). The findings changed the further therapeutic procedure in 16 of 29 patients. Further stenoses were excluded and bronchoscopy was verified in another 13 of 29. Temporal resolution of cine CT and cine MR is sufficient; however, spatial resolution of cine MR is inferior. Paired inspiratory and expiratory spiral CT localises tracheal stenoses and demonstrates relevant extraluminal compression. Significantly improved evaluation of respiratory collapse and further information of localised tracheal instability is obtained by cine CT. Cine MR promises more functional information especially due to free choice of imaging plane.

Adult↗

PubMed2001

Contrast-enhanced three-dimensional MR angiography of the thoracic aorta: experiences after 118 examinations with a standard dose contrast administration and different injection protocols.

The aim of this study was to test three injection protocols for contrast-enhanced magnetic resonance angiography (MRA) of the thoracic aorta with a standard-dose application. Ninety-three patients with a total of 118 examinations underwent MRA of the thoracic aorta at 1.5 T. There were three injection protocols: in 24 cases, no test bolus was performed and contrast was injected manually; in 14 cases, contrast was injected manually after a test bolus; and in 80 cases, a MR-compatible injector was used after a timing examination. All patients received 20 ml of Gd-DTPA. Quantitative signal-to-noise (SNR) measurements were obtained at different locations in the thoracic aorta, the pulmonary arteries, and the superior vena cava. Two readers in conference retrospectively evaluated each examination with respect to overall image quality and quality of bolus timing. Bolus timing was considered optimal in 70 cases, and either too early or too late in 11 cases. In 37 examinations the bolus was broadened. The SNR measurements of the thoracic aorta revealed that examinations after bolus testing were significantly superior to examinations without a test bolus (p < 0.001). Signal intensity ratios of the aorta and the pulmonary trunk were significantly higher in examinations with an optimal contrast timing (p < 0.001). Magnetic resonance angiograms of the thoracic aorta with a timing run are significantly superior to non-timed examinations with respect to image quality and SNRs. The administration of 20 ml of Gd-DTPA is sufficient for adult patients.

Adolescent↗

PubMed2001

Dancing to the tune of chemokines.

Since their discovery 13 years ago, chemokines have emerged as the most important regulators of leukocyte trafficking. On target cells, chemokines bind to seven-transmembrane-domain receptors that are coupled to heterotrimeric Gi proteins. The common response of all cells to chemokine stimulation is chemotaxis. In addition, leukocyte activation triggers diverse signal transduction cascades; which cascade is triggered depends on the chemokine and receptor engaged. The selective activation of distinct pathways suggests that the receptors couple not only to G proteins but also to additional downstream effectors. This review discusses recent advances in the elucidation of the signal transduction that occurs in proximity to receptors and that leads to the early biochemical events in leukocyte activation.

Animals↗

PubMed2001

[MR mammography of response-control in primary chemo-brachytherapy in BCT-inoperable breast cancer].

PURPOSE: To evaluate (1) if neoadjuvant chemo-brachytherapy interferes with MR imaging, (2) if MR can predict the size of the remaining tumor after therapy and (3) if MR can give prognostic information after the onset of therapy. MATERIALS/METHODS: 14 patients enrolled in a preoperative tumor-reduction protocol (4 cycles of chemotherapy combined with interstitial radiotherapy) were examined by dynamic contrast enhanced MR mammography (1 T, temporal resolution 93 s, spatial resolution 1.9 min, 0.1 mmol/kg GdDTPA), before therapy, after the first two cycles of chemotherapy, after radiotherapy and the third cycle, and after completion of therapy. MR findings were evaluated for (1) artificial enhancement after radiotherapy, (2) correlation of enhancement after therapy with histology and (3) changes in enhancement dynamics after the first 2 cycles. RESULTS: (1) 54% of patients had diffuse enhancement that occurred after radiotherapy but vanished before the end of therapy. (2) 4 patients had complete histological remissions after therapy, 3 had dispersed single tumor cells, 7 had remaining nodular tumor. While MR could not differentiate between complete remission and single tumor cells, it accurately predicted the diameter of remaining nodular tumor, except for one case that showed false-positive enhancement. (3) MR dynamics after the first cycles of chemotherapy could not predict overall response. CONCLUSIONS: MR is an accurate tool in assessing tumor response after neoadjuvant chemobrachytherapy. Negative effects from radiotherapy are only transient.

Adult↗

PubMed2001

[Perfusion MR imaging of the heart with TrueFISP].

OBJECTIVE: Development and test of a saturation-recovery TrueFISP (SR-Trufi) pulse sequence for myocardial perfusion MR imaging (MRI) using improved gradient hardware. MATERIAL AND METHODS: Measurements were performed on a 1.5 T scanner with prototype gradients (50 mT/m, minimum rise time 300 microseconds). T1-weighted first-pass MRI of Gd-DTPA (0.025 mumol/kg) kinetics in the myocardium was performed using an SR-Trufi pulse sequence (TR/TE/alpha = 2.6 ms/1.4 ms/55 degrees) with a saturation preparation of TD = 30 ms before the TrueFISP readout. Measurements were performed in volunteers (n = 4) and in a pig model of chronic ischemia (n = 1). RESULTS: In phantoms, the signal intensity was linear with contrast concentration up to 0.9 mmol/kg Gd-DTPA. MR images obtained with SR-Trufi had a good image quality and high spatial resolution of 2.1 mm x 2.1 mm. Differences of the contrast agent's kinetics between a subendocardial perfusion deficit and neighboring myocardium were well visible on both MR images and signal-time curves derived from the region-of-interest analysis. CONCLUSION: SR-Trufi appears to be an interesting new technique for the assessment of myocardial microcirculation using dedicated cardiovascular MR systems.

Adult↗

PubMed2001

[Contrast-enhanced three-dimensional MR angiography of the carotid artery at 1.0 Tesla compared to i.a. DSA: is the method suitable for the diagnosis of carotid stenosis?].

PURPOSE: To evaluate the efficacy of three-dimensional, contrast-enhanced magnetic resonance angiography (CE-MRA) of the carotid artery with a 1.0 T system in comparison to intra-arterial conventional angiography (i.a.CA) for the assessment of carotid artery disease. METHOD: 55 patients with suspected stenosis of the carotid artery were examined with a 3 D-CE gradient-echo sequence on a 1.0 T scanner (TR/TE = 6.2/2.2 ms) and a selective DSA i.a. angiography. Image quality was evaluated by estimating the arterial contrast and venous enhancement. Morphological pathologies were registered for all arteries, stenoses of the internal carotid artery were graded by applying the NASCET criteria. RESULTS: Sensitivity and specificity of MRA in detecting high-grade stenosis (> or = 70%) and occlusion of the extracranial internal carotid artery were 97.7 and 94.0%. Therapeutic relevant misinterpretations were mostly based on overestimating the stenoses. CONCLUSION: The applied CE-MRA technique with a 1.0 T system is suitable for the assessment of carotid artery stenoses. In case of a therapeutically relevant stenosis revealed by MRA, however, verification of the diagnosis by i.a. CA is recommended.

Aged↗

PubMed2001

[Artefact reducing in diagnosis of lung embolism using spiral CT with saline bolus].

PURPOSE: To improve the diagnostic efficacy of bolus-enhanced spiral CT (SCT) in the detection of pulmonary embolism using a saline push immediately after bolus injection of the contrast medium. PATIENTS AND METHODS: The study included 90 patients with suspected acute or chronic pulmonary embolism. The CT scan was performed in a caudocephaled direction. In Group I (n = 60) we applied a bolus contrast injection (120 ml, 3 ml/s, 300 mg J/ml), after a median delay of 25 s. Group II (n = 30) had the same contrast injection which was immediately followed by an additional saline push (60 ml, 2 ml/s). Streak artifacts originating from high contrast concentrations in the superior vena cava were rated on a 4-point scale for different locations: right pulmonary artery, pars basalis, truncus anterior, and the segmental upper lobe arteries. RESULTS: The incidence of artifacts in group I was nearly twice as high as in group II. The difference was significant (p < 0.05) for the upper and anterior superior lobe artery, the right pulmonary artery and the pars basalis. CONCLUSION: The presented protocol significantly reduces artifacts mainly by a washout of contrast medium in the superior vena cava.

Adult↗

PubMed2001

[MRI in chronic epicondylitis humeri radialis using 1.0 T equipment--contrast medium administration necessary?].

PURPOSE: Evaluation of the diagnostic value and confidence of contrast-enhanced MR imaging in patients with lateral epicondylitis in comparison to clinical diagnosis. MATERIAL AND METHODS: 42 consecutive patients with clinically proven chronic lateral epicondylitis and 10 elbow joints of healthy controls have been examined on a 1.0 T MR-unit. Criteria for inclusion in the prospective study were: persistent pain and a failed conservative therapy. The MR protocol included STIR sequence, a native, T2-weighted, fat-suppressed TSE sequence, and a Flash-2-D sequence. Also, fat-suppressed, T1-weighted SE sequences before and after administration of Gd-DTPA contrast media have been recorded. RESULTS: In 39/42 patients the STIR sequence showed an increased SI of the common extensor tendon. Increased MR signal of the lateral collateral ligament combined with a thickening and a partial rupture or a full thickness tear have been observed in 15/42 cases. A bone marrow edema at the lateral epicondilus was noticed in 6 of the studied patients and a joint effusion in 18/42 patients. After administration of contrast media we noticed an average increase of SI by about 150%. However, enhanced MR imaging did not provide additional information. CONCLUSION: In MR imaging of chronic epicondylitis administration of gadolinium-DTPA does not provide additional information.

Adult↗

PubMed2001

[Cryotherapy of malignant tumors: studies with MRI in an animal experiment and comparison with morphological changes].

PURPOSE: Aim of our study was to investigate the efficacy of 7 F cryoprobes for percutaneous use morpho- and histologically, to examine the role of apoptosis after cryotherapy, and to compare contrast-enhanced MRI with histopathological findings at different time intervals in a tumor-mouse model. METHODS: Percutaneous cryotherapy was performed in 15 immunocompromised nude mice with subcutaneously implanted tumors using the non-small-cell lung cancer cell line Lu 1. In group a) 7 mice were sacrificed after definite time intervals and histological examinations were done for evaluation of necrosis and apoptosis (HE; TUNEL assay); 2 mice are in long-term follow-up. In group b) in 6 mice tumor destruction and perfusion before and after freezing were investigated with native and contrast-enhanced MR imaging (T1- and T2-weighted spin-echo) and compared with histopathological findings. Histological control were done in 2 untreated mice. RESULTS: We observed fast tumor-reduction within two weeks (ca. 50%). On long-term follow-up (> 6 months) no recurrence has been noticed so far. Tumors were well vascularized prior to treatment and did not-show contrast enhancement an any time after cryotherapy. A narrow contrast-enhanced zone was seen on the tumor border subcutaneously as a sign of peripheral hyperemia and central vascular stasis after cryotherapy. On histology there was evidence of both apoptosis and necrosis. CONCLUSION: We have established a tumor-mouse model for further investigations. Two minutes freezing of a 2-cm tumor in the mouse model is sufficient for tumor ablation with scarred healing. Apoptosis may play a role in cryotherapy of experimental tumors. Contrast-enhanced MRI is suitable for the estimation of the cryolasion.

Animals↗

PubMed2001

[Evaluation of left ventricular aneurysms before and after surgery using Cine-MRI].

PURPOSE: To demonstrate the usefulness of cine-MRI for the evaluation of apical left ventricular aneurysms (ALVA) and for prediction of the surgical outcome. MATERIALS AND METHODS: We investigated 28 patients with ALVA, 13 of them additionally after aneurysmectomy at 1.5 T; 15 healthy volunteers served as normal controls. For cine-MRI k-space segmented Fl-2D-GE sequences were used. Analysis comprised the calculation of cardiac volume indices, cardiac function, and percentual myocardial thickening (PMT). For prediction of surgical results we divided left ventricle into an aneurysmatic and a non-aneurysmatic part. The non-aneurysmatic part was assumed as the left ventricle after surgical remodelling. RESULTS: Enddiastolic and endsystolic volume indices (EDVIs and LV-ESVIs) were higher in patients with ALVA (123.7 +/- 30.2 ml/m(2), 94.3 +/- 32.5 ml/m(2), respectively) than in volunteers (79.1 +/- 13.9 ml/m(2), 25.5 +/- 5.1 ml/m(2), respectively) (p < 0.001). Stroke volume index (SVIs), cardiac index (CIs) and ejection fraction (EFs) were significantly lower in patients (30.4 +/- 9.1 vs. 54.2 +/- 0.2 ml/beat/m(2); 2.2 +/- 0.8 vs. 3.9 +/- 0.9 l/min/m(2), 26.0 +/- 9.7 vs. 67.9 +/- 4.5 %, respectively) (p < 0.001). There was a significant decrease of LV-EDVIs and LV-ESVIs (102.8 +/- 30.3 ml/m(2), 66.3 +/- 28.0 ml/m(2), respectively) (p = 0,002, p < 0.001, respectively), no change of SVIs (36.4 +/- 6.0 ml/beat/m(2)) (p > 0.05) and a significant increase of CIs and EFs (3.0 +/- 0.6 l/min/m(2), 37.91 +/- 10.15 %, respectively) (p < 0.001) after surgery. We found a good correlation between the preoperatively calculated (32.6 +/- 10.1 %) and the measured EF after surgery (37.9 +/- 9.8 %) (r = 0.70; p = 0.035). PMT was significantly lower in patients than in volunteers (median 11.9 +/- 10.7 vs. 70.2 +/- 13.9 %; p < 0.001), especially in the aneurysmatic parts of left ventricle (median - 6.8 %; p < 0.001). CONCLUSION: Cine-MRI offers accurate evaluation of ALVA and enables preoperative estimation of left-ventricular volumes after surgery.

Aged↗

PubMed2001

[Acute or chronic transplant rejection - high resolution CT of the chest in lung transplant recipients].

PURPOSE: Aim of the study was to evaluate the postoperative changes in patients with single (SLTX) or double lung transplantation (DLTX) with HRCT and to correlate those findings with the clinical diagnosis. MATERIAL AND METHODS: 29 patients with SLTX (n = 14) or DLTX (n = 15) were observed for more than 6 years after transplantation by HRCT (n = 82). CT examinations were performed in inspiration and expiration (n = 70) with a slice thickness of 1 mm and a feed of 10 mm. The image material was evaluated by 2 experienced radiologists in consensus. Criteria for acute rejection at HRCT were: ground glass opacities and focal air trapping in expiration. Criteria for chronic transplant rejection were: bronchial dilatation, bronchial wall thickening and thickening of interlobar septae. The clinical evaluation consisted of laboratory tests, lung function tests, and bronchoscopy including bronchial lavage in special cases. RESULTS: 20/29 patients are still alive (mean 21 months). 5/9 patients died because of chronic transplantant rejection, 1 patient suffered from a non-Hodgkin's lymphoma localised at the right hilus. Severe threatening pneumonia occurred in 13 cases. 10/29 patients showed symptoms of acute rejection. Expiratory HRCT found a focal air trapping in all cases and extended ground glass opacities in 11/14 cases. Also a bronchial dilatation was observed in more than 50 % (9/14). 12/29 patients suffered from chronic transplant rejection. HRCT showed bronchial dilatation in 26/27 investigations and severe ground glass opacities in 21/27 investigations. Thickening of the interlobal septa as well as centrilobular opacities were found in more than 50 % of the examinations. CONCLUSION: High resolution CT of the chest in patients after lung transplantation is able to show numerous pathological alterations. Without clinical information a confident differentiation in acute or chronic transplant rejection or pneumonia can be difficult or impossible.

Acute Disease↗

PubMed2001

[A software tool for automatic image-based ventilation analysis using dynamic chest CT-scanning in healthy and in ARDS lungs].

PURPOSE: Density measurements in dynamic CT image series of the lungs allow one to quantify ventilated, hyperinflated, and atelectatic pulmonary compartments with high temporal resolution. Fast automatic segmentation of lung parenchyma and a subsequent evaluation of it's respective density values are a prerequisite for any clinical application of this technique. MATERIAL AND METHODS: For automatic lung segmentation in thoracic CT scans, an algorithm was developed which uses (a) different density masks, and (b) anatomic knowledge to differentiate heart, diaphragm and chest wall from ventilated and atelectatic lung parenchyma. With Animal Care Committee approval, the automated technique was tested in 8 anaesthetized ventilated pigs undergoing dynamic CT before and after induction of lavage-ARDS. Images were acquired in one supradiaphragmatic, cross-sectional slice (temporal resolution of 100 ms; slice thickness of 1 mm, high resolution reconstruction algorithm). In 120 CT images the total pixel number and the calculated MLD from the automatically segmentated lung were compared to the values obtained from an interactive lung segmentation. RESULTS: The software tool was able to read all image series (DICOM standard). Automatic and interactive segmentation were in high agreement (R(2) = 0.99 for the total number of pixels and the MLD). Originally, the most frequent error was misclassification of atelectasis as extrapulmonary solid tissue. CONCLUSION: An automatic software tool is presented for lung segmentation in healthy lungs and in ARDS. Aerated lung and atelectasis were identified with high accuracy. This post-processing tool allows for a quantitative, CT based assessment of ventilation and recruitment processes in the lung. Thus, it may help to optimize ventilation patterns in patients with ARDS.

Animals↗

PubMed2001

[Hydro-MRI for abdominal diagnostics in children].

PURPOSE: A clinical evaluation of hydro-MRI as an alternative method to barium studies in children with abdominal pain of unknown origin is presented. PATIENTS AND METHODS: 20 children with abdominal pain of unknown origin aged from 9 - 16 years were examined after oral bowel opacification using 1000 ml of 2.5 % mannitol solution with a 1.0 T MRI system. The investigation was done in 2 planes (coronal and axial) under breath-hold conditions. Imaging procedures included various sequences (T2W HASTE + FS, contrast-enhanced T1W FLASH FS). Suspicious findings in bowel segments and extra-intestinal changes were assessed. RESULTS: In 21/24 examinations the small bowel was completely visualized, in 15/24 cases colon segments were identified. An accurate assessment of the terminal ileum was not possible in 3/24 procedures. Breathing artefacts occurred in 3/24 examinations. Signs of Crohn's disease were found in 4 examinations, inflammatory changes of the ileum were detected in 3 cases. Inflammation of the colon was demonstrated in 2 children. Furthermore, pathological findings included constipation in one child and inflammation of the ileo-colic and mesenterial lymph nodes were found in another child. Extra-intestinal changes in 3 children were caused by ovarian cysts, and in one case by pleural effusion. In 4 examinations we detected ascites in the absence of other pathological findings. In 5 children there was no pathological correlation in the bowel or extra-intestinal region for the complaints. The children tolerated the hydro-MRI very well. There were no side effects using oral mannitol. CONCLUSION: Hydro-MRI is a valuable non-invasive method in the diagnosis of abdominal pain of unknown origin. In children it should be the method of choice because it further offers the advantage of the absence of ionizing radiation. Patient compliance is a prerequisite for this new examination. In our experience this requirement was met in children older than 9 years. Further studies should prove the necessity of conventional radiology following negative hydro-MRI.

Abdominal Pain↗