Digitale Bilddiagnostik最新文献

To investigate possibilities of magnetic resonance imaging at high magnetic fields in humans, a whole-body magnet with a magnetic field density of 4 T was developed. Due to the few data that are available at present on biological effects and side effects of such high fields, a reproduction experiment with NMRI mice was performed using a crossover design. The mice were allowed to mate during a 7-day period within the field or after their stay in the field. The number of pregnant mice and foetuses were recorded and compared to the controls. Another group was held within the magnetic field during the whole period of pregnancy until day 18, one day before delivery. In all groups, development of the foetuses was studied. Additionally, haematological parameters of the males and females were estimated and necroscopy was performed. Brains, lungs and optical nerves were investigated using pathohistological techniques. It could be shown that in case of mating within the magnetic field, the number of pregnant mice was considerably reduced. This effect was, however, completely reversible if mating occurred after the stay in the field. Malformations, retardations or an increased number of resorptions were never found. The haematological parameters were, in general, not changed. Necroscopy as well as pathohistological investigations showed no pathological alterations. Therefore, it appears that whereas high magnetic fields reduce the activity of mating behaviour, they do not exert any influence on physiological parameters.

The article is a compilation of data on the radiation exposure during the most important CT examinations. The influencing parameters are assessed and their effects are discussed. Conclusions are drawn to modify the practical approach. These results are compared with those reported in international literature.

In 57 rats the radiation absorption or proton relaxation times were determined in vitro after single carbon tetrachloride poisoning. The inflammatory changes induced by CCl4 result in marked water absorption and moderate of fat. Histologically, there are cell necroses, toxic swellings of cells, regenerating cells rich in water content, and fatty vacuoles. These phenomena result in a reduction of radiation absorption due to the increased water and fat accumulation. Prolongation of both relaxation times is mainly due to water absorption.

The use of CT in hospitals in which also ENT departments are located will be useful in cases of osseous congenital disorders of the ear. In combination with the clinical and audiometric investigations CT of the temporal bone will be helpful for the indication of the operations to ameliorate the hearing.

Different views about the value of a colour monitor for the evaluation of computer tomograms have prompted us to carry out this ROC (Receiver Operation Characteristic) examination. The latter was based on patient computer tomograms in which lesions of the liver were simulated by image manipulation. 5 radiologists analysed the image material (a) on a black-and-white monitor, (b) on a colour monitor, and (c) simultaneously on a black-and-white and a colour monitor. The study shows that the use of a colour monitor gives no essentially different result than evaluation with a black-and-white monitor. The slightly better result of 2% more true positive findings with simultaneous representation of black-and-white and colour image relative to the sole use of black-and-white display is within error limits. The colour representation gives no advantage for the evaluation of usual computer tomograms because the window technique enables a contrast representation in black-and-white too.

Radioimmunoscintigraphy is presented as a new imaging modality in nuclear medicine, using specific antigen-antibody interactions. Monoclonal antibodies to tumor-associated antigens facilitate the characterization of molecular differences between tumors and normal cells. Labelled with gamma-emitting radioisotopes like I-131, I-123, In-111, and Tc99M, these antibodies can be used for in-vivo imaging. Radioimmunoscintigraphy does not compete with morphological modalities like CT and ultrasound, but provides additional information based on its functional principle. Hidden lesions may be detected. Target-to-background ratios, however, are still rather low hampering scintigraphic imaging. The use of Single Photon Emissions Computed Tomography (SPECT) in addition to planar scintigraphy resolves background activities thus providing better visualization and localization of tumors, and increasing sensitivity. The high cost of these time-consuming studies is still a limiting factor to its wider use. Its preliminary indication is founded on the suspicion of tumor progression, based on clinical findings and/or increasing serum tumor markers (CEA, CA 19-9, CA 12-5). This paper provides an overview over possible applications of radioimmunoscintigraphy. Its clinical use is demonstrated by studies of malignant melanoma, colorectal cancer and ovarian cancer.

Kidney diseases, healthy kidney tissue and adjacent organs like liver, musculature and fatty tissue were evaluated in respect to their T1-, T2-relaxation times and proton density values. In addition the results of an evaluation of T2-short, T2-long, Rho-short, Rho-long, which were calculated from the T2-relaxation times, are reported. The T2-times are very sensitive in demonstrating differences between the tissues, as significantly different values for healthy kidney tissue and hypernephromas could be found. Different values could be seen dependent on the calculation mode, whereby the calculations had been made from double echo and multiple echo sequences. The T1-relaxation times were less sensitive, differences could be also found between the calculations from the IR and SE mode. The values of T2-long and T2-short and the proton density values differed very much for the same organ in the examined groups of patients, therefore these additionally calculated values unlikely will help in the differential diagnosis of unknown kidney diseases.

Amebic liver abscesses are the most frequent clinical manifestations of the extra-intestinal amebiasis and have to be considered as a serious complication in the course of disease. The abscesses have by their risk of rupturing and bacterial superinfection quoad vitam an unfavourable prognosis. CT-guided relief punctures can, as it is demonstrated by two cases of critical amebic abscesses, effectively improve the therapy with systemic amebicides, prevent imminent rupture and contribute to the healing of the abscesses. Thus a surgical treatment of the abscess was not necessary.

The accuracy of magnetic resonance imaging (MRI) and computed tomography (CT) in the staging of bladder tumors was evaluated in 46 patients. In the T-staging MRI was superior to CT. With MRI 38 out of the 46 tumors were correctly staged into the four groups T0, T1-T3a, T3b and T4. With CT this classification was only possible in 28 cases. The main advantages of MRI were the capability for multiplanar imaging, which improved evaluation of the bladder base and the bladder dome, as well as a better differentiation between tumor recurrency and fibrosis. In the evaluation of adenopathy MRI and CT proved to be equal and demonstrated a sensitivity of 50%.

The use of dual energy methods in digital radiography allows selective imaging of soft tissues or calcified structures and contrast media. The value of this method is demonstrated on the basis of 400 patient examinations. The isolated imaging of soft tissues without skeletal superposition gives particular advantages in diagnosis of the chest and the cranio-cervical region. Soft tissue calcifications and calcium-containing concrements in the bile ducts and in the urinary tract are well demonstrated without soft tissue superposition. The disadvantages and the limits of the method are discussed, its potential and possible future developments are shown.