Biomedical subjects

C Schorn

Publications and source records attributed to C Schorn.

12 recordsLinked to original sources

PubMed2006

[Differential diagnosis of rheumatic diseases].

UNLABELLED: QUESTION TO ANSWER: Which imaging modalities are appropriate for the Differential diagnosis of Rheumatic diseases. METHODS AND RESULTS: MRI has far most the highest sensitivity and is unequaled in its brilliant presentation of anatomy and pathology. But it is sometimes forgotten, that this is at least in part the result of carefully selected sequences, dedicated to the expected result. CONCLUSION: Plain X-ray offers high specificity in the differential diagnoses of rheumatic diseases, it is well standardised and it is a device, to use independent from any suspected findings.

Diagnosis, Differential↗

PubMed2005

[Imaging techniques in rheumatology: conventional radiography in rheumatoid arthritis].

Conventional radiography is still regarded the gold standard for imaging techniques in rheumatoid arthritis (RA). It is a very important tool for the diagnosis, the differential diagnosis, and the evaluation of the course and prognosis of the disease. Special advantages of conventional radiography are the worldwide availability and experience with the method over decades and the relatively low costs. Moreover, x-rays can be stored and re-evaluated over long periods of time. Joint damage caused by RA can be quantified by means of scoring methods. The amount of destruction correlates well with functional disability over time. The inhibition of damage progression seen on radiographs is the most important characteristic of a DMARD. Typical radiographic changes are part of the ACR classification criteria of RA. Technically, bone structure can be demonstrated with a high local resolution better than with all other imaging techniques, whereas only indirect conclusions can be drawn concerning soft tissue and cartilage lesions. This review includes recommendations given by the "Commission on Imaging Techniques" of the German Society of Rheumatology regarding technical and personal preconditions, costs, indication as well as practical performance of radiography in RA. In addition, radiographic changes that can be expected in RA including destruction and repair are discussed briefly.

Arthritis, Rheumatoid↗

PubMed2002

[Quality management in a radiology department].

PURPOSE: To increase the quality of internal and external interactions (patients, clinical colleagues, technicians, radiologists) in a department of radiology. METHOD: Accompanied by a well-experienced adviser workshops have been performed dealing with different topics like "contact to patients," "performance of the radiological report and interaction with the referring colleague" or "research and teaching." A catalogue of different actions was defined to reduce hindrances within the internal and external work-flow. RESULTS: A total number of 53 actions was defined and related to different persons who were responsible for the realisation of the measures within a time interval. Six months after starting the quality management 46 (86%) of the defined actions were realised successfully, and another 4 (8%) measures were still running. There was a moderate increase of satisfaction of the patients and clinical colleagues considering the waiting time. CONCLUSIONS: A quality management in a radiological department allows an optimisation of the internal and external interactions. However, the guidance of a well-experienced adviser is as essential as the continuous control of successful finished measures.

Education↗

PubMed2001

HMSC: simultaneously detected heteronuclear shift correlation through multiple and single bonds.

A new 2D pulse sequence HMSC (heteronuclear multiple-bond and single-bond coupling connectivities) for the simultaneous detection of long-range and one-bond heteronuclear connectivities is proposed which allows the two types of responses to be separated and the corresponding (n)J(CH) and (1)J(CH) connectivity maps to be calculated. (n)J(CH) coherences are selectively labeled in the course of the pulse sequence, the correspondingly acquired data are separately stored, and a simple add/subtract procedure is applied to disentangle and edit (n)J(CH) and (1)J(CH) responses prior to final data processing. Unlike standard methods, which are designed to measure one single type of heteronuclear spin-spin interactions and to efficiently suppress the other, both (n)J(CH) and (1)J(CH) are measured simultaneously in a single experiment with the HMSC pulse sequence. Compared to the common strategy with two standard experiments applied one after the other, e.g., HMBC and HMQC, valuable measuring time may be saved with this single experiment approach. The efficiency of the new pulse sequence and the quality of the corresponding spectra are demonstrated using strychnine. Features such as sensitivity, lineshapes, and the suppression of (1)J(CH) residual peaks in the final (n)J(CH) subspectra are investigated and compared with the corresponding results obtained with standard methods. The attractive and unique single experiment approach, its high efficiency, and its easy experimental setup together with straightforward data processing make HMSC a valuable experimental alternative for the today's more time-consuming "two-step" practice and makes it suitable for standard routine applications.

Journal Article↗

PubMed2000

[Virtual endoscopy of the upper airway with spiral CT].

PURPOSE: The technical conditions, the optimized scanning protocols and the facilities of virtual endoscopy (VE) are presented in an overview. METHODS: Phantom studies showed that, for a single-row-detector helical CT, collimation of 3.0 mm combined with pitch of 1.5 provided an optimal compromise between image quality and the scan duration per breath-hold. A multi-row-detector helical CT requires only a fraction of the scanning time. This is especially important for patients with dyspnea. RESULTS: The threshold-dependent virtual endoscopic surface rendering is a reliable and rapidly practicable reconstruction algorithm for the imaging of the upper airway. CONCLUSIONS: The VE technique is suitable for the imaging of space-occupying tumors and restricted stenoses. With VE follow-up examinations can be performed non-invasively and interventional procedures can be prepared in an optimal way. Because of the computed tomographic data acquisition the structure of the mucosa is not assessable and there is no opportunity to obtain a biopsy specimen.

Bronchoscopes↗

PubMed2000

[Full-field digital mammography: a phantom study for detection of microcalcification].

OBJECTIVES: The study compares direct full-field digital mammography (FFDM) to the state-of-the-art conventional screen-film mammography (SFM) concerning the detectability of simulated microcalcifications. MATERIALS AND METHODS: The investigations were performed with a FFDM system (Senographe 2000D, GEMS) and a SFM system (Senographe DMR, GEMS, Fuji UM MA film with Fuji UM MAMMO FINE screen). An anthropomorphic breast phantom with superimposed microcalcifications (50-200 microns) was used to evaluate the detectability of microcalcifications with a confidence level ranging from 1 to 5. Contact mammograms and magnification spot views (m = 1.8) of the FFDM and SFM systems were compared. A receiver operating characteristic (ROC) analysis was performed by three well-experienced readers. RESULTS: The ROC analysis revealed a higher performance of the digital images compared to the conventional screen-film mammograms. The area under the ROC-curve (Az) in the digital contact mammograms was 0.68 versus 0.63 in the conventional technique. The results were not significantly different. In digital spot views, Az was 0.79 versus 0.70 in the conventional spot views. CONCLUSIONS: The results suggest that FFDM is at least equivalent or--as far as spot views are concerned--may be superior to conventional SFM in the detection of microcalcifications.

Breast Diseases↗

PubMed2000

[Full-field digital mammography: dose-dependent detectability of breast lesions and microcalcinosis].

OBJECTIVES: The study compares contrast-detail and microcalcification detectability of a full-field digital mammography (FFDM) to a state-of-the-art conventional screen-film mammography (SFM) by using different doses in the digital system. MATERIALS AND METHODS: The investigations were performed with an FFDM (Senographe 2000 D, GEMS) and an SFM system (Senographe DMR, GEMS) using a contrast-detail mammography phantom (CDMAM) and an anthropomorphic breast phantom with superimposed microcalcifications. The digital detector was exposed with standard dose of SFM and with a dose reduction of up to 75%. Contrast-detail curves and correct observation ratio (COR) were performed for the CDMAM phantom. ROC analysis with a confidence level ranging from 1 to 5 was done with the results of the anthropomorphic phantom. RESULTS: Digital mammography with the same dose revealed at least an equivalent or even higher detectability rate than conventional mammography, COR could be increased at about 10-25%. The ROC analysis yielded better results for the FFDM system. The same lesion detectability in digital mammography as in the conventional method was reached at a dose reduction of about 25%, concerning spot views even at higher reduction. Dose reduction in the anthropomorphic phantom resulted in a linear loss of detectability. The same detectability as in conventional mammography was reached, however, by a dose reduction of about 50%. CONCLUSION: The results suggest that FFDM is at least equivalent to or--as far as spot views are concerned--superior to conventional SFM concerning the detectability of simulated lesions. Thus, a potential of dose reduction is suggested.

Breast Diseases↗

PubMed1999

MRI of the breast in patients with metastatic disease of unknown primary.

The objective of this study was to assess the value of contrast-enhanced dynamic breast imaging in patients with carcinoma of unknown primary (CUP). Fourteen patients presenting with metastatic disease compatible with breast cancer (axillary lymph node metastasis: n = 6; supraclavicular lymph node metastasis: n = 1; bone metastasis: n = 3; liver metastasis: n = 3; lung metastasis: n = 1), who had no evidence of tumor in X-ray mammograms and ultrasound, underwent bilateral dynamic breast MR imaging. Suspicious lesions were localized preoperatively using a stereotactic device for MR-guided localization procedures. Magnetic resonance imaging revealed suspicious lesions in 9 of 14 patients. Histopathology revealed invasive carcinoma of the breast in 6 of these patients. Two enhancing lesions were fibroadenomas; one proved to be sclerosing adenosis. In 5 patients MR imaging showed no abnormality. Follow-ups performed up to 1 year after initial treatment revealed no breast cancers in these 5 patients. In patients with metastatic disease of unknown primary, MRI of the breast depicts the primary in a considerable number of cases with normal conventional evaluation.

Adult↗

PubMed1999

[Slice sensitivity profile and image pixel noise of multi-slice spiral CT in comparison with single slice spiral CT].

PURPOSE: Presentation and evaluation of slice sensitivity profile and pixel noise of multi-slice CT in comparison to single-slice CT. METHODS: Slice sensitivity profiles and pixel noise of a multi-slice CT equipped with a 2D matrix detector array and of a single-slice CT were evaluated in phantom studies. RESULTS: For the single-slice CT the width of the slice sensitivity profiles increased with increasing pitch. In spite of a much higher table speed the slice sensitivity profiles of multi-slice CT were narrower and did not increase with higher pitch. Noise in single-slice CT was independent of pitch. For multi-slice CT noise increased with higher pitch and for the higher pitch decreased slightly with higher detector row collimation. CONCLUSIONS: Multi-slice CT provides superior z-resolution and higher volume coverage speed. These qualities fulfill one of the prerequisites for improvement of 3D postprocessing.

Artifacts↗

PubMed1999

[Dental CT: image quality and radiation exposure in relation to scan parameters].

PURPOSE: To develop a scan protocol for dental-CT which guarantees good image quality at the lowest possible radiation dose. METHODS: In an experimental investigation Dental-CT (HSA, GE, Milwaukee, USA) of the mandible of two human skeletons positioned in a water tank were performed in order to define the most advantageous scan protocol. Tube currents ranged from 40 to 200 mA and the scan technique was modified (axial mode or helical mode with pitches of 1 to 3 and corresponding increments of 0.4 to 1.0 mm). 39 patients underwent a dental-CT with decreased current (80 mA) in the helical scan mode (pitch 2, slice thickness 1 mm). Dose measurements were performed for two different scan protocols (A: axial, 130 mAs, B: helical, 80 mA, pitch 2). RESULTS: The preliminary investigations of image quality showed only a minor effect of the applied current. For the helical scan mode, pitches of more than 2 impaired image quality. A low increment had no advantages. There were no disadvantages in clinical practice using protocol B with decreased tube current. Absorbed radiation dose of dental CT performed with protocol B was decreased to one third in comparison to protocol A. CONCLUSIONS: A scan protocol with a low tube current (e.g., 80 mA, for a rotation time of 1 s) and a helical scan mode (e.g., for a slice thickness of 1 mm with a pitch of 2 and an increment of 1 mm) is recommended for performing dental-CT.

Adult↗

PubMed1998

Compression device to reduce motion artifacts at contrast-enhanced MR imaging in the breast.

A prototype compression device for a bilateral breast surface coil was manufactured. It was tested in clinical practice (157 patients), and resultant images were compared with those obtained with simple ventral stuffing of the bottom of the coil (181 patients). Compression resulted in reduction of magnetic resonance (MR) examinations with severe motion artifacts from 20 (11%) of 181 examinations to three (2%) of 157 examinations (P = .001). Use of this compression device allowed the subtraction technique at MR imaging in the breast to become an effective method for ensuring more lesion conspicuity.

Artifacts↗

PubMedDate not supplied

Diagnostic potential of ultrafast contrast-enhanced MRI of the breast in hypervascularized lesions: are there advantages in comparison with standard dynamic MRI?

PURPOSE: Our goal was to evaluate possible diagnostic advantages of ultrafast MRI of the breast in comparison with dynamic MRI. METHOD: Thirty patients with 35 hypervascularized lesions were selected prospectively after undergoing standard dynamic MRI (temporal resolution 87 s). Patients underwent additional ultrafast imaging (temporal resolution 2 s). Onset, rate, and pattern of enhancement were analyzed. RESULTS: Histopathology revealed 15 malignant and 20 benign lesions (3-40 mm). Enhancement pattern was centripetal in 2 benign and 4 malignant lesions, centrifugal in 5 and 3, and homogeneous in 13 and 8. The onset of lesion enhancement ranged from 3 to 13 s (parenchymal enhancement 4-14 s) and the rate of enhancement from 3 to 70%/s, both without any correlation to the histologic diagnosis. There was no significant difference between ultrafast and standard dynamic MRI. CONCLUSION: Ultrafast MRI does not provide additional information in comparison with standard dynamic MRI.

Adolescent↗