Biomedical subjects
Publications and source records attributed to C Zwicker.
184 liver metastases in 30 patients were examined retrospectively and the imaging in sonography, dynamic CT and plain CT was compared. Dynamic CT is markedly superior to plain CT and sonography in respect of the delineation of liver metastases, especially also in the identification and location of diffuse metastases.
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Fifty patients with various diseases of the petrous bone were examined by HR-CT with a 1024 x 1024 matrix. It is demonstrated that the improved spacial resolution results in a better discrimination of subtle anatomical structures and therefore leads to an expansion of the diagnostic possibilities in diseases of the auditory and vestibular organs. Evaluation of the two-dimensional reconstructed images shows that best quality is obtained with contiguous 1 mm, sections in the primary scans. In most cases these reconstructed images are diagnostically sufficient. In addition they help to reduce patient strain (no problem with patient positioning, no further x-ray exposure, time-saving). Three-dimensional reconstructions from the base of the skull allow a good visualization of complex and extensive osseous destructions of the temporal bone. The disadvantage of this method is on the one hand the lacking representation of soft tissue and the poor spacial resolution (no 3-D imaging of the ossicular chain), and on the other hand the smoothing of contours because of arithmetical filters. Thus tumor expansion and finer osseous erosions may not be distinguishable. Consequently, 2D primary or reconstructed images must continue to be the basis of diagnosis.
This is a prospective study of the value of dynamic CT with a rapid scan frequency for the control of liver transplants. In 28 patients dynamic CT was performed with table movement and angio-CT without table movement, using a standard contrast bolus. In 97% of cases the central portions of the portal and hepatic veins could be delineated. The peripheral vessels were better demonstrated by angio-CT (79%) than by dynamic studies with table movement (47%). Parenchymal lesions, such as infarcts, and changes round the liver, such as lymphoedema or haematomas, were adequately demonstrated by either method. In addition, angio-CT provided information on abnormalities of perfusion within the transplant.
In this prospective study 39 patients with malignant liver tumours were examined by rapid CT. CT was performed before contrast, as dynamic CT, with and without table movement and, in some patients, images were obtained four hours after contrast injection. Time/density curves of hepato-cellular carcinomas (nine cases) showed more rapid and more intense enhancement of the tumour than of the liver parenchyma, whereas tumours of biliary origin (ten cases) showed a slower and less marked enhancement than surrounding tissue. In addition, it was possible to differentiate hypovascular metastases (18 cases) and hypervascular lesions by means of the time-density curve. Best diagnostic information was obtained by dynamic bolus CT. This method without table movement is best for differentiating focal lesions, whereas dynamic CT with table movement shows the extent and number of tumour lesions.
In 25 patients in whom oral surgery was required, we examined what additional information can be obtained via three-dimensional CT compared with conventional transverse CT scans. We showed that D-3 CT facilitated the spatial orientation by complex osseous destructions. Better therapy planning and postoperative control was therefore feasible. However, CT diagnosis continued to be based on transverse scans.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Radioimmunoscintigraphy (RIS) with 131I labeled OC-125 F(ab')2 monoclonal antibody fragments was prospectively studied in 43 women for primary diagnosis and follow up of ovarian cancer. Total body planar photoscans with a scintillation camera were performed one to seven days after antibody application and results were compared with operation and or CT examination. By the region of interest technique the tumor to non tumor tissue ratio (T/N) was calculated in vivo. Sensitivity in primary diagnosis was 100% (10/10), specificity 33% (1/3). For local recurrency, sensitivity was 86% (19/22), for metastatic loci 80% (17/21). Specificity was 75% and 50%. T/N ratio was in the rage from 1.3 to 2.8. Sensitivity for ovarian cancer is high in primary diagnosis and follow up. By the region of interest technique it is possible to detect small recurrencies and to presume peritoneal carcinosis. Antibody accumulations in diseases different from ovarian cancer however diminish specificity.
In a retrospective study, the clinical usefulness of digital image intensifier radiography was analysed. It could be demonstrated that for angiographic procedures the image quality of a 1024(2) matrix is superior to a 512(2) matrix. For digital excretory urography it could be seen that in 80 to 90% the images were at least sufficient to analyse the renal pelvis. Digital image intensifier radiography of bones was diagnostically sufficient in 76% and analysis of bone architecture was possible in 85%.
In a prospective study, 150 threedimensional reconstructions of patients with bone diseases were analyzed. It could be seen that 3 D images were relevant for therapeutic considerations in diseases of craniofacial bones, and to a lesser degree for other skeletal regions. In no case was the 3 D reconstruction the only important factor for the therapeutic decision. The study demonstrated that 3 D imaging of the pelvic bones, especially for necroses of the femoral head, is severely limited without the possibility of computer-aided disarticulation.
The ultrasound findings of 58 patients with AIDS and ARC were analysed retrospectively. In 55% an enlarged liver, in 62% an enlarged spleen, partially with focal lesions, and in 21% enlarged abdominal lymph nodes were diagnosed. The typical focal segmental glomerulosclerosis of the kidney was observed in one case, and cholangitis in 2 patients. Abdominal ultrasound is the first diagnostic procedure to be performed in patients with AIDS and ARC when abdominal pathology is suspected. With US-guided thin needle puncture of the lesions, a histological verification of the pathologic findings is possible.
The quality of radiographs representing corkscrew vessels and collateral vessels that developed after occlusion of the superior femoral artery, using digital angiography technique with a 1024 matrix, is compared with that of a 512 matrix. The images obtained with the 1024 matrix were superior to those obtained with a 512 matrix. Using a small cannula for the application of the contrast agent, the quality of the images representing the collateral vessels was very good in 83% of the images produced with the 1024 matrix and in 70% of the 512 matrix images.
Today the best radiotherapeutic procedure for treating small choroidal melanomas involves the application of rhutenium 106, thereby sparing the bulbus, or application of iodine 125 in larger tumors. In extensive tumors, the additional use of local hyperthermia promises further enhancement of brachytherapy with applicators. In the foreseeable future, therapeutic concepts primarily for the palliative treatment of advanced, metastasing melanomas might include the use of antimetabolites or therapy with monoclonal radioactively changed antibodies.
The use of digital image radiography in urographic diagnostics yields a high percentage of images that are useful in diagnosis, even at the present state of technical development which is rapidly improving. Our own results obtained in a prospective study on 75 patients supply proof of such diagnostically useful pointers. Clear improvements in demonstrating the details when employing a 28 cm image amplifier input format in place of the additionally used 40 cm are seen only with the system of the renal calices. However, we found that the 40 cm image amplifier input format proved satisfactory in respect of assessing renal contours, kidney pelvis and ureters as far as image quality was concerned. Enhance image quality can be expected in future from the use of wedge-shaped diaphragms as well as a selective influencing of the automatic exposure (several measurement chambers, weighting factors) and the transfer of monitor screen contents to hard copy without incurring any losses during transfer.
33 CT-studies of 26 patients with alloplastic vascular prostheses were evaluated and compared with postoperative digital subtraction-angiography in 16 cases. 13 patients had no pathologic findings confirmed by further clinical development. In 4 cases bypass infection was diagnosed, which CT findings were perigraft gas (2/4), perigraft fluid (4/4), cm-enhancement (4/4) and fistulas (2/4). 10-21 d. post.-op. sterile hematomas were found in 3 patients. Further 3 cases had 5 weeks-2 post.-op. perigraft seromas. CT was method of first choice for diagnostic of perivascular alterations after bypass surgery. DSA was complementary to CT and should be performed to detect vascular complications.