Digitale Bilddiagnostik最新文献

Blood flow velocity in the common carotid arteries was measured for 30 vessels by MRI with a multiecho SE-sequence and compared with the results from duplex ultrasound. MR blood flow velocity was measured for a time interval of 390 ms every 30 ms using a EKG-triggered data acquisition. The time-velocity curves measured by MRI and duplex ultrasound were in good agreement. The correlation coefficient for the peak velocity was r = 0.83. Mean peak velocity as measured by MRI was 59 +/- 8% of peak velocity as measured by duplex ultrasound.

Imaging of the normal bronchial system by CT was examined in 75 patients while employing different imaging parameters. The main and lobar bronchi could be demonstrated almost without exception in the standard examination of the thorax. Segmental bronchi were delineated in an average of 81% of the cases (512 image matrix) or 74% (256 image matrix), respectively. The lowest identification rate was seen in the segmental bronchi of the middle lobe and lingula being 38% (512 image matrix) and 18% (256 image matrix), respectively. Increase of the magnification factor did not result in any significant improvement of imaging. An increase in the identification rate of the segmental bronchi of the middle lobe and lingula was achieved only after reducing the slice thickness from 8 mm to 4 mm, the yield being now 87% (512 image matrix) and 82% (256 image matrix), respectively, whereas the remaining segmental bronchi could be made to show up almost without exception. The standard parameters are sufficient for routine examination of the bronchial system. If imaging is diagnostically not satisfactory, reducing the slice thickness yields improved imaging, especially of small bronchi.

As in other radiological examinations there is an essay to show the ossicles and their surrounding tympanic walls of the petrous bone in the high resolution computed tomography. This should be standardized to simplify the interpretation and to allow the comparison. For the axial imaging of the ossicles corresponding to their particular topographic situation the head is tilted to the non-examined side and a little bit dorsally flected to turn especially the stapes in the scanning plane and to image the malleus and incus axially. The standard slices of the tympanon were schematized with the help of pictogramms. This allows a faster orientation and an easier recognition of a changed topographical situation meaning a pathological condition. The coronary view is as the important second part of the HR CT of the petrous bone integrated.

The benign segmental bronchial obstruction--mostly discovered on routine chest films--can well be diagnosed by CT. The specific findings in CT are the site of the bronchial obstruction, the mucocele and the localized emphysema of the involved segment. Furthermore CT allows a better approach to the underlying process.

The authors describe the CT findings in 10 cases of pulmonary aspergillosis which include allergic bronchopulmonary aspergillosis, aspergilloma and invasive pulmonary aspergillosis. CT reveals a more distinct radiologic-pathologic correlation than plain films and shows suggestive features of pulmonary aspergillosis earlier and in a more detailed fashion. Thus the use of CT in the appropriate clinical setting should allow earlier diagnosis than conventional radiography.

Density-time-functions after intravenous contrast medium injections are simultaneously taken by a computer tomograph in the region of the aorta and the cortex of the kidney or the region of the aorta and a tumor respectively. The differential equation system resulting from this is solved explicitly on the basis of a compartment model. The resulting functions are related to the density-time functions. These functions include the constants of distribution velocity and discharge velocity. They are modified by application of an iteration procedure (computer programme) to ensure the adequate correspondence between the curves and the density-time-trends. Between the constants of inversion velocity and eversion velocity of the cortex of the kidney, there is a linear as well as allometric relationship, the correlation amounts to r = 0.99. In the case of all tumors, only an allometric relationship (r = 0.92) could be found as regards the conversion constants.

Prolonged dynamic CT up to 32 minutes after intravenous bolus injection of 100 ml contrast medium improves the differentiation between benign (hemangiomas) and malignant (metastases) liver lesions. Our study shows that there are three distinct types of hemangiomas and that all three of them behave differently than metastases. Prolonged dynamic improves the problem of differentiation between hemangiomas and metastases but does not solve the problem completely.

Hitherto T1-weighted Spin-Echo-Sequences, most combined with T2-weighted sequences, were used to detect pathological bone marrow lesions. This method needs a long examination time and results in T2-images with a low morphological resolution. In the majority of examinations using Gradient-Echo-Sequences with prolonged repetition-times (FLASH: flip angle 40 degrees, TR/TE = 500/17 msec) there is no need of an additional measurement. Therefore these sequences save about 75% of the examination time and they give higher contrast between normal and pathological bone marrow.

This paper is concerned with fast MR-imaging, realised by several "fast sequences", introduced during the last few years into clinical routine diagnostics. Two of the most important fast sequences are FLASH and FISP--their physical and technical working as well as their relevant clinical imaging properties are described.

In 10 pts. with mitral valve lesions dense spontaneous echographic contrast was found within the left atrium by transoesophageal echocardiography. Because of the neurologic symptoms some of the patients also had (transitoric ischemic attacks, embolism) left atrial thrombosis was suspected. The echographic phenomenon of spontaneous left atrial contrast was further examined by magnetic resonance imaging in all 10 pts. Using the spin-echo-mode the multi-echo-imaging showed dense signals in the second echo and no or few left atrial signals in the first echo in 8/10 pts. In 2/10 pts. there were no increased signals in left atrium. The missing presence of the increased signals in the first echo excluded thrombosis of the left atrium and proved blood flow effects.