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M Taupitz

Publications and source records attributed to M Taupitz.

At least 19 recordsLinked to original sources
PubMed2003

[Modern imaging modalities in renal disease: CT and MRI].

Considerable technical advances have been made in computed tomography (CT) and magnetic resonance imaging (MRI) over the last 10 years. Both modalities allow for high-resolution imaging of the entire abdomen before as well as during the arterial and parenchymal perfusion phase after intravenous contrast medium administration. Multiplanar reconstructions of the three-dimensional source data sets yield views in any spatial orientation. Maximum intensity projections enable the generation of CT or MR angiographies as well as CT or MR urographies from delayed images. Thus, both modalities today allow for comprehensive diagnostic evaluation of renal disease by a single examination comprising detailed visualization of the parenchyma as well as of arterial and venous vessels and assessment of excretion. CT and MRI thus enable efficient preoperative diagnostic assessment in particular in patients with renal masses.

Humans↗
PubMed2003

Use of iodine-based contrast media in digital full-field mammography--initial experience.

AIM: To investigate the use of iodine-based contrast media in digital full-field mammography. METHODS: After performing initial phantom studies, seven patients underwent digital mammography (Senographe 2000D, GE Medical Systems, Milwaukee, USA) using a specially filtered beam before as well as 60, 120, and 180 seconds after injection of 80 ml of iodine contrast medium (Ultravist 370, Schering AG, Germany). The precontrast mammograms were then subtracted from the postcontrast mammograms and the resulting images compared with a contrast-enhanced dynamic MRI study, performed on all women. RESULTS: Contrast medium accumulation within the tumors was visualized with a good quality in all cases. The conditions under which successful contrast-enhanced digital mammography can be performed were determined in phantom studies. CONCLUSIONS: Contrast-enhanced digital mammography has a potential for improving the visualization of breast tumors in mammography using special beam filtering, adjusted x-ray parameters, proper timing, and suitable subtraction software.

Breast Neoplasms↗
PubMed2003

[MRI of prostate cancer using three different coil systems: image quality, tumor detection, and staging].

PURPOSE: To compare three MRI coil systems in terms of image quality, delineation of prostate cancer, and tumor staging. MATERIALS AND METHODS: 49 patients with prostate cancer underwent MRI at 1.5 Tesla using a combination of an endorectal coil with a phased-array body coil (combination coil) prior to radical prostatectomy. Images were reconstructed from the data sets acquired with the endorectal coil alone and from those acquired with the combined coil. In addition, 19 patients of the study patients were examined with the body phased-array coil alone without the endorectal coil. The prostate was imaged at a slice thickness of 3 mm using axial and coronal T 2 -weighted sequences and an axial T 1 -weighted sequence. Preoperative analysis of all images acquired was done to determine the accuracy of MRI in local staging of prostate cancer. An additional retrospective analysis served to compare the different coil systems in terms of overall image quality, delineation and localization of the tumor, and criteria for local staging of prostate cancer. RESULTS: Preoperative analysis showed MRI to have an accuracy of 59 % in local tumor staging. Retrospective coil-by-coil analysis demonstrated image quality and tumor delineation to be best for the combination coil and the endorectal coil. Regarding the staging criteria for transcapsular tumor extension and infiltration of adjacent organs, a significant advantage of the combination coil compared to the endorectal coil was identified only for the criterion of smooth bulging. In addition, the endorectal coil and the combination coil were found to be superior to the body phased-array coil in assessing 15 of 17 criteria for local tumor staging but the differences were not significant. CONCLUSION: In view of the achieved superior image quality, the combination coil or the endorectal coil is the preferred method for staging prostate cancer.

Aged↗
PubMed2003

[MR angiography of the coronary arteries: comparison of the blood pool contrast medium Gadomer and Gd-DTPA in pigs].

AIM: To investigate the signal-enhancing effects of the macromolecular contrast medium Gadomer in MR angiography of the coronary arteries compared to Gd-DTPA. MATERIAL AND METHODS: A total of 15 MRI examinations of the heart were performed in pigs at 1.5 T using a pulse-triggered, segmented 3D FLASH sequence with data acquisition during breathhold before and up to 30 min after contrast medium injection. Gadomer was investigated at two doses (0.05 and 0.1 mmol Gd/kg), Gd-DTPA at one (0.3 mmol Gd/kg) (n = 5 examinations per dose). Standard sequences without magnetization preparation were supplemented by sequences with magnetization saturation applied before data acquisition before and immediately after contrast medium injection. Analysis comprised quantitative determination of blood and myocardium signal to noise (S/N) and contrast to noise (C/N) and qualitative assessment of several parameters of image quality and coronary artery visualization. RESULTS: Gadomer leads to a significant C/N increase between blood and myocardium compared to the unenhanced examination and the increase is longer-lasting than that produced by Gd-DTPA (Gd-DTPA: only directly after injection; Gadomer: up to 5 min post injection at 0.05 mmol Gd/kg, up to 10 min at 0.1 mmol Gd/kg). The qualitative evaluation shows that visualization of the coronary arteries and branch vessels is significantly better with Gadomer at both doses than with Gd-DTPA. Magnetization saturation increases the C/N in combination with Gd-DTPA and at the higher dose of Gadomer with the latter producing a higher increase in C/N values. CONCLUSION: Gadomer is a suitable contrast medium for MR angiography of the coronary arteries with the dose of 0.1 mmol Gd/kg being superior to 0.05 mmol Gd/kg due to a longer imaging window.

Animals↗
PubMed2003

[Superparamagnetic iron oxide particles: current state and future development].

A wide range of applications for superparamagnetic iron oxide (SPIO) particles as contrast media for MRI has emerged over the last 15 years. SPIO particles can be manufactured with different particle sizes and surface coatings. Large SPIO particles (50-150 nm) predominantly produce a signal decrease or T2 -shortening and are used as contrast media for MRI of the liver and spleen. They have a high accuracy, especially in detecting liver metastases (approved for clinical use: AMI-25 (Endorem or Ferridex), SHU-555A (Resovist)). Smaller particles (about 20 nm in diameter) show a different organ distribution and have a potential for improving noninvasive lymph node assessment or characterizing vulnerable atherosclerotic plaques (in clinical trials: AMI-227 [Sinerem or Combidex]). Particles with an optimized T1-relaxivity and prolonged intravascular circulation time can be used as blood pool contrast media for MR angiography. The currently investigated indications are MR angiography of the trunk, peripheral vessels, and coronary arteries (e.g., SHU-555 C (Supravist), VSOP-C 184). Other applications of small SPIO particles include MRI of the bone marrow and the determination of perfusion parameters in tumors or other tissues like the myocardium. SPIO particles with a modified coat can be used in so-called molecular imaging, such as receptor-directed imaging, cell labeling for in-vivo monitoring of cell migration, e.g., stem cell labeling, and labeling of gene constructs for localization in genetic therapy. In tumor therapy SPIO particles can serve as mediators for hyperthermia. SPIO is a powerful MR contrast medium with manifold applications ranging from diagnostic imaging to molecular medicine.

Animals↗
PubMed2003

Visualization of the pulmonary valve using cine MR imaging.

PURPOSE: To evaluate the capability of bright-blood cine MR to directly visualize the leaflets of the valve replacement in pulmonary position following Ross operation. MATERIAL AND METHODS: Long and short axis views of the pulmonary valve were obtained in 10 normal subjects and 14 patients after Ross operation. Valve morphology and function were analyzed and signal-to-noise (SNR) and contrast-to-noise ratios (CNR) were calculated. Flow measurements were performed in the pulmonary trunk to assess pulmonary regurgitation. RESULTS: In all subjects, tricuspid morphology of the pulmonary valve was visualized. SNR of the leaflets in normal subjects (9.8 +/- 3.0) and in patients after Ross operation (7.5 +/- 2.2) differed significantly from blood (12.6 +/- 3.2 and 11.3 +/- 2.5, respectively, p < 0.05). Valvular regurgitation was seen in 5 patients as an insufficient closure of the valve which was confirmed by flow measurements. CONCLUSION: Cine MR enables in-plane visualization of the pulmonary valve and allows for functional and morphological evaluation in patients after pulmonary valve surgery.

Adult↗
PubMed2002

Bounded-depth threshold circuits for computer-assisted CT image classification.

We present a stochastic algorithm that computes threshold circuits designed to discriminate between two classes of computed tomography (CT) images. The algorithm employs a partition of training examples into several classes according to the average grey scale value of images. For each class, a sub-circuit is computed, where the first layer of the sub-circuit is calculated by a new combination of the Perceptron algorithm with a special type of simulated annealing. The algorithm is evaluated for the case of liver tissue classification. A depth-five threshold circuit (with pre-processing: depth-seven) is calculated from 400 positive (abnormal findings) and 400 negative (normal liver tissue) examples. The examples are of size n=14,161 (119 x 119) with an 8 bit grey scale. On test sets of 100 positive and 100 negative examples (all different from the learning set) we obtain a correct classification close to 99%. The total sequential run-time to compute a depth-five circuit is about 75h up to 230h on a SUN Ultra 5/360 workstation, depending on the width of the threshold circuit at depth-three. In our computational experiments, the depth-five circuits were calculated from three simultaneous runs for depth-four circuits. The classification of a single image is performed within a few seconds.

Algorithms↗
PubMed2002

[Image quality and detection of pathology by ultrasound: comparison of B-mode ultrasound with photopic imaging and tissue harmonic imaging alone and in combination].

PURPOSE: To determine the accuracy of photopic imaging (PI) in detecting pathology by ultrasound (US) and to assess the image quality in direct comparison with conventional B-mode ultrasound and tissue harmonic imaging (THI). MATERIAL AND METHODS: Fifty-two patients underwent US examination, among them 29 patients for abdominal assessment and 23 for otolaryngological assessment. A total of 208 freeze frames, 52 B-mode scans each with and without THI and 52 B-mode scans each with and without PI, were assessed by three readers, who determined the presence of pathology on a scale of 1 (definitely abnormal) to 5 (definitely normal). All 52 patients underwent US follow-up within six weeks. The results were confirmed by CT in 30 patients and by histology in five cases. Image quality and different color encodings of each technique were rated on a ranking scale of 1 (optimal) to 4 (poor). The different US techniques were compared in terms of image quality, diagnostic accuracy, and color encoding using McNemar's test and ROC analysis. RESULTS: The results for image quality were as follows: B-scan 3.9; THI 1.9; PI 2.8; and THI plus PI 1.5 (each p < 0.05). The following AUCs (Area under Curve, presence of pathology) were calculated: 0.925, 0.990, and 0.990 for B-mode US, THI, and PI, respectively (not significant), and 0.994 for THI plus PI (significant compared to B-mode scan). The different color encodings were rated as follows: reddish brown 1.6, gray 1.9, blue 3.1, and green 3.6 (each p < 0.05). CONCLUSION: For ultrasound examinations, PI in combination with THI improves the image quality and conspicuity of pathology.

Abdomen↗
PubMed2002

Iron-oxide-enhanced magnetic resonance imaging of atherosclerotic plaques: postmortem analysis of accuracy, inter-observer agreement, and pitfalls.

INTRODUCTION: Contrast-enhanced magnetic resonance (MR) imaging using ultra small superparamagnetic iron oxide (USPIO) particles is a new noninvasive modality for imaging inflammatory atherosclerotic plaques. We determined the accuracy, interobserver agreement, and potential sources of error of this technique by means of postmortem MR imaging of aortic preparations. MATERIAL AND METHODS: Anesthetized atherosclerotic Watanabe heritable hyperlipidemic (WHHL) rabbits were studied after administration of different dosages of intravenous USPIO (DDM 43/34, IDF Berlin, Germany) and different postcontrast time intervals. A (n = 5) received 0 micromol Fe/kg. B (n = 5) received 50 micromol Fe/kg, 8-hour postcontrast interval. C (n = 5) received 50 micromol, 24 hours. D received 200 micromol, 48 hours. The aortas were removed and 3-mm segments prepared for postmortem examination by MR imaging using a T2-weighted gradient-echo sequence (TR/TE/FA; 41 milliseconds/11 milliseconds/15 degrees ), radiography (mammography), and histology (iron staining). USPIO accumulation was defined as the presence of 20 iron-positive cells per microscopic view (x100 magnification). Two independent readers analyzed the MR images and rated their confidence level for a positive MRI finding, defined as a focal signal loss, on a 5-point scale. The results were evaluated by receiver-operator characteristic (ROC) analysis. RESULTS: Of a total of 621 vessel segments technically acceptable for evaluation, 534 were histologically negative and 87 positive. Accuracy, expressed as the area under the ROC curve, was 0.85 for reader 1 and 0.88 for reader 2. Interobserver agreement was 0.67. False-positive findings were established by at least one reader for 121 of the 621 segments, false-negative findings for only 15 segments. Calcifications and mural thrombi were identified as potential sources of error of the method. CONCLUSION: Postmortem USPIO-enhanced MR imaging of atherosclerotic plaques showed a high accuracy and good interobserver agreement in the animal model used here. Further optimization of the method should aim at reducing the rather high percentage of false-positive results.

Animals↗
PubMed2001

Magnetic resonance imaging of atherosclerotic plaques using superparamagnetic iron oxide particles.

Experimental data show accumulation of superparamagnetic iron oxide (SPIO) particles in atherosclerotic plaques. SPIO uptake occurred in plaques, suggesting an increased endothelial permeability and macrophage infiltrates as signs of inflammatory plaque activity. We incidentally observed SPIO uptake in aortic and arterial wall segments in patients who had originally received the magnetic resonance (MR) contrast agent for staging lymph node metastases. Twenty patients (19 male, 1 female; mean age, 64; range, 41-78 years) with bladder or prostate cancer underwent MR imaging (MRI) using a T2*-weighted high-resolution gradient-echo sequence prior to and 24-36 hours after intravenous injection of 2.6 mg of Fe/kg of SPIO (Sinerem). The aorta, both common external and internal iliac, as well as both superficial femoral arteries, were retrospectively analyzed for atherosclerotic wall changes. One patient was excluded. A positive finding was defined as an area of pronounced signal loss on postcontrast images clearly confined to the arterial wall, which was absent in the precontrast examination or increased in size. Such a finding was observed in one to three arteries in 7 of the 19 patients. The pronounced signal loss in the wall of the aorta and pelvic arteries seen in part of an elderly patient population after intravenous SPIO administration strongly suggests that this contrast agent accumulates in human atherosclerotic plaques.

Adult↗
PubMed2001

Coronary magnetic resonance angiography: experimental evaluation of the new rapid clearance blood pool contrast medium P792.

The signal-enhancing characteristics of a new monodisperse monogadolinated macromolecular MR contrast medium (P792) were evaluated for magnetic resonance angiography (MRA) of the coronary arteries. A total of 15 cardiac examinations were performed in pigs at 1.5 T using a 3D gradient-echo sequence. Images were acquired during breath-hold before and up to 35 min after IV injection of Gd-DTPA (0.3 mmol Gd/kg), Gd-BOPTA (0.2 mmol Gd/kg), and P792 (13 micromol Gd/kg). An increase in the signal-to-noise ratio (SNR) of 97% +/- 17%, 108% +/- 37%, and 109% +/- 31% in coronary arteries and of 82% +/- 19%, 82% +/- 24%, and 28% +/- 18% in myocardium, respectively, was measured during the first postcontrast acquisition. The blood-to-myocardium signal-difference-to-noise ratio (SDNR) was significantly higher for P792 than for the other Gd compounds (P <.05) for up to 15 min after injection. Qualitative assessment showed that visualization of the coronary arteries and their branches was significantly better for P792 compared to the low-molecular Gd compounds (P <.05). The blood pool contrast medium P792 is well suited for MRA of the coronary arteries.

Animals↗
PubMed2001

Patent ductus venosus: diagnosis by MR angiography.

We report a 15-year-old boy with patent ductus venosus in whom the diagnosis was made by MR angiography. A patent ductus venosus Arantii is a rare form of portosystemic shunt. Only a few cases have been reported in adults and children. The diagnosis is usually made by US and digital subtraction angiography. In our patient, the diagnosis was first made by MR angiography. This demonstrates the excellent diagnostic potential of the method in paediatric patients.

Adolescent↗
PubMed2001

Sectional depiction of the pelvic floor by CT, MR imaging and sheet plastination: computer-aided correlation and 3D model.

The structures of the pelvic floor are clinically important but difficult to assess. To facilitate the understanding of the complicated pelvic floor anatomy on sectional images obtained by CT and MR imaging, and to make the representation more vivid, a computer-aided 3D model was created from a male and a female torso to develop a teaching tool. A male and a female cadaver torso were investigated by means of CT, MR imaging, and serial-section sheet plastination. A 3D reconstruction of the pelvic floor and adjacent structures was performed by fusion of CT and MR imaging data sets with sheet plastination sections. Corresponding sections from all three methods could be compared and visualized in their 3D context. Sheet plastination allows distinction of connective tissue, muscles, and pelvic organs down to a microscopic level. In combination with CT, MR imaging, and sheet plastination a 3D model of the pelvic floor offers a better understanding of the complex pelvic anatomy. This knowledge may be applied in the diagnostic imaging of urinary incontinence or prolapse and prior to prostate surgery.

Anatomy, Cross-Sectional↗
PubMed2001

Gadolinium-enhanced MR angiography of the breast: is breast cancer associated with ipsilateral higher vascularity?

The aim of this study was to assess a possible association between breast malignancy and ipsilateral higher vascularity on gadolinium-enhanced MR angiography. One hundred six patients were examined by dynamic gadolinium-enhanced 3D MR imaging. Magnetic resonance angiographic views were generated by image subtraction and maximum intensity projection. The study included 85 patients with unilateral malignant breast neoplasms and 21 with unilateral benign lesions. Three blinded readers independently reviewed the MR angiograms after masking the lesions and the corresponding contralateral sites. The readers were asked to determine whether vascularity was higher on the right side, higher on the left side, or equal on both sides. The results were analyzed by the Kappa statistic and Pearson's chi-square test. The blood vessels of the breasts were clearly seen in all cases. There was good agreement among the observers (kappa > 0.54) in assessing vascularity on both sides. Breasts harboring malignant neoplasms were found to have a higher vascularity than the contralateral breasts (p < 0.005). This sign of malignancy had a sensitivity of 76.5%, a specificity of 57%, and an accuracy of 72.6%. Blood vessels of the breast can be depicted by MR angiography. Unilateral malignant neoplasms are associated with a higher ipsilateral vascularity. In conjunction with other indications of malignancy on gadolinium-enhanced MR images, a higher ipsilateral vascularity may serve as an additional sign of malignancy.

Adult↗
PubMed2001

Diagnostic difficulties before definitive treatment of an extragonadal retroperitoneal germ cell tumor.

A primary extragonadal germ cell tumor of the retroperitoneum was diagnosed in a 47-year-old man without elevated serum alpha-fetoprotein, human chorionic gonadotropin, or lactate dehydrogenase levels. The diagnosis was made by histologic analysis after resection. The patient responded well to a combination of cisplatin, etoposide, and ifosfamide, achieving a partial response with four cycles. Residual tumor resection revealed necrotic tissue only. The patient was alive and disease free 24 months after diagnosis. The diagnostic difficulties of this particular situation are discussed.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2001

Logarithmic simulated annealing for X-ray diagnosis.

We present a new stochastic learning algorithm and first results of computational experiments on fragments of liver CT images. The algorithm is designed to compute a depth-three threshold circuit, where the first layer is calculated by an extension of the Perceptron algorithm by a special type of simulated annealing. The fragments of CT images are of size 119x119 with eight bit grey levels. From 348 positive (focal liver tumours) and 348 negative examples a number of hypotheses of the type w(1)x(1)+. . .;+w(n)x(n)>/=theta were calculated for n=14161. The threshold functions at levels two and three were determined by computational experiments. The circuit was tested on various sets of 50+50 additional positive and negative examples. For depth-three circuits, we obtained a correct classification of about 97%. The input to the algorithm is derived from the DICOM standard representation of CT images. The simulated annealing procedure employs a logarithmic cooling schedule c(k)=Gamma/ln(k+2), where Gamma is a parameter that depends on the underlying configuration space. In our experiments, the parameter Gamma is chosen according to estimations of the maximum escape depth from local minima of the associated energy landscape.

Algorithms↗
PubMed2001

[Contribution of MRI in diagnosis of urinary stress incontinence without concomitant urogenital prolapse].

PURPOSE: To detect pathomorphological changes of the pelvic floor, the vagina, and the urethra by MR imaging in patients with stress urinary incontinence in the absence of organ descent compared with findings in 10 healthy controls. MATERIALS AND METHODS: The study included 10 healthy controls and 38 patients with stage II urinary incontinence showing no urge symptoms but a pathological stress profile on urodynamic testing. The subjects underwent MR imaging with a phased-array coil at 1.5 T in addition to urodynamic testing and gynecological examination. The following sequences were used: axial and coronal PD-weighted TSE sequences with a FOV of 20 cm and a section thickness of 4 mm; axial STIR sequence. Sagittal T2-weighted HASTE sequences were acquired during pelvic floor contraction, relaxation, and straining maneuvers. RESULTS: In 22/38 cases pathomorphological changes were found by MR imaging. The pathomorphological changes were classified as lateral defects (n = 14) if the musculofascial connection between the levator muscle and the lateral vaginal wall or the butterfly shape of the vagina was absent and as central (n = 16) if changes were detected in the urethral wall. Defects of the pelvic floor muscles were detected in 8 cases. No underlying changes were identified in 16/38 cases. CONCLUSION: In cases of female urinary incontinence, MR imaging of the pelvic floor can detect pathomorphological changes, which are difficult to identify by clinical examination. MR imaging currently does not allow the detection of morphological changes in all forms of female urinary stress incontinence.

Adult↗