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Biomedical subjects

C Zwicker

Publications and source records attributed to C Zwicker.

At least 37 records · Page 2Linked to original sources

[Bolus administration in spiral CT of the upper abdomen].

In 60 patients the density increases in the abdominal aorta and pancreas were examined quantitatively the visualisation of the arterial liver blood flow qualitatively in a test volume by means of spiral CT and a feed or speed differentiation of 10 mm/s for three different contrast medium boli. It was shown that during the entire study over 24 seconds the boli with 100 ml contrast medium at injection speeds of 3 ml/s and 50 ml contrast medium at 1.5 ml/s resulted in a continual density increase of the abdominal aorta from 221 to 265 Hounsfield Units (HU) or 161-167 HU, respectively. For measuring the abdominal aorta the bolus of 50 ml contrast medium at 3 ml/s was less suitable than the boli of 100 ml contrast medium with 3 ml/s and 50 ml with 3 ml/s because of the rapid in density from 250 to 118 HE. The bolus of 50 ml contrast medium and 3 ml/s, on the other hand, with 54 HU enhancement of the pancreas was approximately equal to the larger amount of contrast medium of 100 ml contrast medium and 3 ml/s with 56 HU, whereas 50 ml contrast medium and 1.5 ml/s with 46 HU was inferior. While all boli could sufficiently enhance the extrahepatic section of the hepatic artery, the larger amount of contrast of 100 ml proved to be superior to the other boli in the visualization of central intrahepatic vascular branches.

Adult↗

[Catheter-induced femoral artery lesions: diagnosis with B-mode ultrasound, Doppler ultrasound and color Doppler ultrasound].

A total of 44 patients were evaluated to compare the value of B-mode sonography, Doppler sonography and colour coded Doppler sonography. All patients were studied because of suspected lesions of the femoral arteries following diagnostic and/or therapeutic cardiac catheterisation. B-mode sonography was unable to reliably differentiate between haematoma and pseudo-aneurysms, a.v.-fistula or combined lesions. Colour coded Doppler sonography can better demonstrate haematoma and thrombi in pseudo-aneurysms. The neck of a pseudoaneurysm can be exactly depicted by colour coded Doppler sonography. A.v.-fistula is shown by colour coded Doppler sonography based on typical colour coding and the Doppler spectrum. Combined lesions of pseudo-aneurysm and a.v.-fistula cannot reliably be detected by colour coded Doppler sonography, duplex sonography and B-mode sonography.

Adult↗

[The value of radioimmunoscintigraphy compared to computed tomography in the diagnosis and relapse diagnosis of colorectal tumors].

Radioimmunoscintigraphy (= RIS, scintigraphic "specific" imaging of benign and malignant diseases by means of radioactively marked monoclonal antibodies) has been performed in Germany in clinical studies since 1985 in patients suffering from colorectal cancer. After having been successfully proven in primary studies, RIS is now being used in the early diagnosis of recurrences and metastases. In the prospective study presented here the clinical usefulness of RIS was assessed in comparison against well-tried diagnostic methods including computed tomography in patients suffering from colorectal cancer. It was shown that RIS in SPECT technique (= single photon emission computed tomography) with 99mTc-labelled monoclonal CEA antibodies can visualise local recurrences if diagnostic findings are doubtful, with a sensitivity of 78% versus 50% for CT findings.

Adult↗

[The HR computed tomography of interstitial lung diseases].

In 50 patients with pulmonary disease of varying aetiology and involvement of the pulmonary interstitium, high resolution CT with 1 mm sections have been performed. Various morphological changes within the secondary lobule could be demonstrated which helped in reducing the differential diagnosis. Compared with conventional CT with 10 mm cuts it was also possible to improve the demonstration of pleural lesions by changing window levels.

Asbestosis↗

[The visualization of bony and vascular structures in digital subtraction images depending on the contribution of the anatomical background].

We examined the loss of contrast leaving a part of the anatomic background in digital subtraction angiography by visual analysis and densitometry. We observed a greater loss of the quality at the representation of the bone below than above an amount of anatomic background of 60%. The loss of quality at the representation of the vessels decreases more above than below an anatomical background of 45%. We think that, depending on the clinical problem, an anatomical background between 15 and 30% should be left.

Angiography, Digital Subtraction↗

[Computed tomography: the TNM staging of laryngeal carcinoma].

In 64 patients with malignant lesions of the larynx, CT and microlaryngoscopy (ML) were evaluated in terms of T-staging. Histological information was present in all cases following operation. CT showed an accuracy of 90% in T-staging. ML showed an accuracy of only 71% of correct T-staging. CT is superior to ML particularly in distinguishing between stages T3 and T4 and T1 and T2. CT tends to overestimate tumour stage whereas ML tends to underestimate it. CT was also compared with palpation and sonography as regards N-staging. In this respect sonography has the highest accuracy (94%) followed by palpation (76%) and CT (74%).

Carcinoma↗

[Catheter-induced vascular lesions: a comparison of the diagnostic value of Doppler color sonography versus angiography].

One hundred and thirty-two patients with suspected lesions of the femoral arteries following diagnostic and/or therapeutic cardiac catheterisation were studied by colour Doppler sonography (CDS) and digital subtraction angiography (DSA) and the results were compared. CDS was unable to demonstrate 5 out of 23 av fistulae. Intra-arterial DSA showed all av fistulae found at operation. CDS showed lower reliability (95%) than DSA (100%) for the demonstration of pseudoaneurysms. CDS can indicate hematoma and thrombi in pseudo-aneurysms and their exact extent is better shown by sonography. Arterial dissections (2 cases) and intra-luminal thromboses or occlusions of the femoral artery (4 cases) are shown equally well by the two procedures.

Adult↗

[The value of nuclear magnetic resonance tomography in tumor staging of laryngeal-/hypopharyngeal cancer].

Twenty-four patients with tumors of the larynx and hypopharynx were examined with magnetic resonance imaging (MRI) and laryngoscopy. The results of MRI and laryngoscopy were then correlated with the pathology reports. Diagnostic findings of 84% of the MRI studies correlated with the pathology report, while laryngoscopy provided exact classification in 79%. MRI tended to overestimate tumor size because edema or inflammatory reactions of surrounding tissues simulated tumors. However, normal mucosa also enhanced contrast medium, restricting the value of this technique. Laryngoscopy tended to underestimate tumor size, because deep extensions of tumor and cartilage involvement were difficult to detect. Nonetheless, the utility of MRI in obtaining axial, coronal and sagittal slices was found to facilitate the preoperative staging of tumor extensions.

Carcinoma, Squamous Cell↗

[Reactive enlargement of cervical lymph nodes and cervical lymph node metastases: sonography (M/Q quotient) and computed tomography].

Ranking of sonographic maximum/transverse diameter quotients was compared with the ranking of CT in respect of identification and exclusion of cervical lymph node metastases. Both sonography and CT are distinguished by a high degree of sensitivity in the imaging of cervical lymph node metastases. Sonography, with the assistance of the maximum/transverse diameter quotient, can differentiate between benign enlarged and non-enlarged lymph nodes on the one hand and cervical lymph node metastases on the other, with a safety of 95 per cent. CT can yield definite information regarding the tumour status only after contrast medium administration under the criteria of central hypodensity and peripheral marginal enhancement. CT is much less specific than the sonographic M/T quotient (66% vs 95%). Accuracy of sonography (94%) is clearly superior to that of CT (79%).

Adult↗

[Cervical lymph node metastasis: significance of computerized tomography and palpation. A histologically controlled comparison].

Palpation and CT are used before treatment, in addition to sonography, in patients with tumours in the head and neck for lymph node staging. The accuracy of CT in identifying lymph node metastases is 79% and in our clinical material is similar to the accuracy of palpation (81%). Sensitivity of CT (93%) is better than palpation (82%). Specificity of CT (65%) is less than that of palpation (82%). The high percentage of false positives from CT (35%) is due to enlargement of the lymph nodes resulting from sinus histiocytosis or follicular hyperplasia. CT is significantly superior to palpation in demonstrating the relationship of the lymph nodes to the surrounding tissues (vessels, muscles, bones).

Adult↗

[Lymphocytic infiltrations of the orbit in MRT and CT. Lymphoma, pseudolymphoma and inflammatory pseudotumor].

MR and CT examinations of 16 patients with lymphoma, pseudolymphoma and inflammatory pseudotumours were analysed to describe morphologic features of lymphocytic infiltration. Density and signal did not allow for differentiation, but localisation was the most important criterion: lymphoma and pseudolymphoma were located in the anterior superior orbit, inflammatory pseudotumours being retrobulbar lesions. Differentiation is of clinical importance, since both lymphoma and pseudolymphoma are accompanied by generalised malignant lymphoma while inflammatory pseudotumours are localised. Imaging of topographic relations of lens, optic nerve and lesion on sagittal MR images was found helpful for radiation therapy planning.

Adult↗

[Three-dimensional computerized tomography of fractures].

In 32 patients with fractures of different localisation the transverse CT layers were compared with three-dimensional reconstructions. Evaluation showed that three-dimensional CT can better visualize complicated anatomical conditions especially if there are dislocated fragments in the facial part of the skull and in the trunk of the body. Hence, 3-D CT is a valuable complement to axial CT which, however, remains the basis of the findings. Misinterpretations are possible of the reconstructions are used alone because of the lack if visualization of the lesions of the soft parts that accompany fractures and because there may be pseudoforamina at thin osseous lamellae.

Adolescent↗