PubMed Health⌕ Search

Biomedical subjects

M D Häussler

Publications and source records attributed to M D Häussler.

12 recordsLinked to original sources
PubMed1999

MRI of primary lymphoma of bone: cortical disorder as a criterion for differential diagnosis.

To investigate the pattern and dimension of cortical bone abnormality on magnetic resonance imaging (MRI) as a feature to distinguish primary lymphoma of bone from osteosarcoma and Ewing sarcoma, 46 patients with primary malignant bone lesions with a soft tissue mass (16 osteosarcomas, 15 Ewing sarcomas, 15 lymphomas) were examined with MRI (T1-weighted pre-/postcontrast spin-echo sequences and T2-weighted spin-echo and fast spin-echo sequences; 1.5 T system). Qualitative image analysis revealed no differences for signal characteristics and enhancement. Lymphomas appeared significantly more often homogeneous (47%; Ewing sarcoma 20%; osteosarcoma 6%/o), and patients were significantly older (cutoff point 30 years). Lymphomas showed significantly less frequent cortical abnormality (60%; Ewing sarcoma 87%; osteosarcoma 100%), complete penetration (13%; Ewing sarcoma 67%; osteosarcoma 87%), focal destruction (13%; Ewing sarcoma 40%; osteosarcoma 81%), and complete destruction (0%; Ewing sarcoma 13%; osteosarcoma 19%). In conclusion, primary lymphoma of bone is characterized by minimal cortical changes despite an accompanying soft tissue mass in a patient over 30 years of age.

Adolescent↗
PubMed1996

[High dosage Gd-DPTA-BMA (Gadodiamid) administration in diagnosis and therapeutic monitoring of malignant bone tumors].

PURPOSE: To evaluate the efficacy of high-dose Gd-DTPA-BMA (gadodiamide, Omniscan) as a contrast for magnetic resonance imaging of malignant bone tumors and the use of high-dose dynamic studies for predicting the response to pre-operative chemotherapy. MATERIALS AND METHODS: Examinations were performed in 22 patients with suspected malignant bone tumor on a 1.5 T system. In 8 cases a follow-up examination was done after preoperative chemotherapy. Static studies included Pd- and T2-weighted spin-echo sequences as well as T1-weighted spin-echo sequences, obtained pre- and post-contrast. Dynamic studies were performed using a FLASH 2D-gradient-echo sequence (TR 40 ms/TE 10 ms, 90 degrees flip angle) every 20 s after intravenous bolus injection of Gd-DTPA-BMA (0.3 mmol/kg body weight). MR images were evaluated qualitatively by visual assessment of conspicuity size, extraosseous delineation and structure of the lesion and quantitatively by measurement of the signal intensities and calculation of the relative increase in signal intensity. RESULTS: Qualitative image analysis showed best demonstration of the lesions on contrast-enhanced T1-weighted images. Comparison of T1-weighted pre- and postcontrast spin-echo sequences revealed significantly better assessment of tumor structure after administration of contrast media. After preoperative chemotherapy, all responders showed a markedly stronger reduction in relative increase in signal intensity in dynamic studies compared to nonresponders. CONCLUSION: Gd-DTPA-BMA is effective for magnetic resonance imaging of musculoskeletal lesions and improves assessment of the tumor structure. Dynamic studies may help to predict the response to preoperative chemotherapy.

Adolescent↗
PubMed1996

Artificial spine fractures: detection with helical and conventional CT.

PURPOSE: To compare the accuracy of detection of artificial spine fractures with helical computed tomography (CT) versus conventional CT. MATERIALS AND METHODS: Twenty-six motion segments from 15 human cadaver thoracolumbar spines were imaged with helical and conventional CT both before and after fractures were artificially induced. The vertebrae were scanned with different collimations, reconstruction indexes, and exposure doses. A total of 900 images were analyzed by four radiologists, and a receiver operating characteristic (ROC) analysis was performed. RESULTS: ROC analysis showed a large area under the curve for conventional CT (0.913) than for helical CT (0.844) when 3-mm collimation was used. The ability to detect fractures with helical CT increased when collimation was decreased and exposure dose was increased. CONCLUSION: Conventional CT allows more accurate detection of artificial spine fractures than does helical CT. Helical CT requires thinner collimation for fracture detection comparable with that of conventional CT.

Cadaver↗
PubMed1995

[The magnetic resonance tomography of Ewing's sarcomas: the morphology and tumor extension].

PURPOSE: The morphology and delineation of Ewing sarcoma in magnetic resonance imaging was investigated. METHODS AND MATERIALS: Magnetic resonance images (spin-echo techniques; T1-w pre/post gadolinium, T2-w) of 59 patients as part of a multicenter study were evaluated retrospectively. Qualitative image analysis was performed: signal intensity (point of reference extraosseous: muscle, intraosseous: bone marrow), enhancement patterns, lesion delineation and differentiation between tumor and oedema. RESULTS: Signal intensity: T1-w: extraosseous: 75% isointense, intraosseous: 92% hypointense; T2-w extraosseous: 100% hyperintense, intraosseous: 93% hyperintense. Enhancement pattern: 97% both extra- and intraosseous. Best delineation intraosseous in T1-w (53% good, 36% very good), extraosseous in gadolinium enhanced T1-w (46% good, 37% very good) and T2-w (55% good, 33% very good). Differentiation between tumour and oedema was intraosseous not possible, extraosseous in T2-w in 61%. CONCLUSION: Morphology of Ewing sarcoma in magnetic resonance imaging is rather uniform. The lesion is intra- and extraosseous sharply delineated, though tumour and oedema can be rarely differentiated.

Adolescent↗
PubMed1994

[The value of the InSight HC asymmetric film-screen system in thoracic diagnosis].

The asymmetric film-screen system InSight HC represents a development to optimize chest imaging. The purpose of the study was to compare the exposure range and the image quality of this new system with a conventional film-screen system. The optical density of images in both techniques was measured and the image quality of 100 chest images from 50 intensive-care patients was evaluated. 4 observers graded the image quality of organic, non-organic and pathological structures. Statistical evaluation was performed by interobserver analysis. The asymmetric film-screen system shows a larger exposure range and a superior image quality in the mediastinal field. The image quality in the peripheral field must be judged critically and improved especially because of the poor recognizability of pneumothoraces.

Evaluation Studies as Topic↗
PubMed1994

[Reconstruction possibilities following resection of malignant musculoskeletal tumors].

Great advances have been achieved in the treatment of musculoskeletal tumors, and as a result limb-conserving resection is now possible in most cases. These advances are based on adjuvant therapy, development of histological criteria, new surgical techniques, and improved imaging methods. The use of computed tomography and magnetic resonance imaging has allowed more accurate preoperative staging. At the same time, an improvement in prognosis has also been achieved. After resection of the tumor, the following methods of reconstruction are available: reconstruction with no implant, endoprosthetic replacement, autogenous grafting, and allograft replacement. Postoperative monitoring is performed with plain-film radiography.

Bone Neoplasms↗
PubMed1992

[The imaging of regional brain perfusion with dynamic magnetic resonance tomography].

Bolus injections of gadolinium-DTPA result in high contrast concentration in the distal vessels within the brain and cause a local disturbance of the magnetic field with a shortening of T2 relaxation time. Pulse frequencies were designed to demonstrate inhomogeneities in the magnetic field. The resultant reduction in T2-weighted gradient echo signals was used in order to examine changes in regional perfusion caused by pathological conditions. Cerebral tumours showed variable perfusion patterns but were always better perfused than surrounding brain tissue; oedema surrounding the tumour resulted in reduced perfusion. Ischaemic infarcts showed significant underperfusion compared with control areas. In both groups the areas involved were larger on the perfusion scans than on T2-weighted images.

Brain↗
PubMed1992

[The value of tumor volumetry as opposed to bidimensional determination of tumor size during follow-up of hepatic metastases from colorectal carcinoma].

36 patients with liver metastases due to colorectal carcinoma under treatment with arterial perfusion chemotherapy of the liver with 5-fluoro-2-desoxyuridine (FUDR) via a subcutaneous pump were investigated by axial liver CT at 6-monthly intervals. In all examinations a dynamic CT scan with intravenous bolus injection of contrast medium was carried out following a native scan. Changes in tumour size were documented by means of 1. volumetry and 2. bidimensional measurement according to WHO criteria. Since we were not able to assess small newly developing lesions within the liver using the volumetric classification, the WHO-classification showed much higher sensitivity in cases of progressive disease. In addition, volumetric determination of tumour size by means of region-of-interest technique proved to be rather impracticable in clinical routine compared to bidimensional measurement.

Aged↗
PubMed1992

[Radiation dosage during hysterosalpingography using a digital image intensifying technique].

Hysterosalpingography using a digital and conventional image intensification technique was carried out on two groups of 32 patients as part of investigation for infertility. Radiation dose was recorded as surface dose. In 51.7% of digital images and 54.8% of conventional images the findings were normal. Surface dose with conventional technique was 442 +/- 144 cGy/cm2, significantly higher than 207 +/- 113 cGy/cm2 with digital image intensification. The number of exposures was also significantly higher when using the conventional technique. The digital images showed no lack of diagnostic detail when compared with the conventional 100 mm films.

Adult↗