Biomedical subjects

C Claussen

Publications and source records attributed to C Claussen.

At least 37 records · Page 2Linked to original sources

PubMed1986

CT of the postoperative lumbar spine: the value of intravenous contrast.

Sixty-five patients with recurrent radicular complaints after operation for lumbar disc herniation underwent CT examination before and after intravenous contrast application (volume: 1.5-2.0 ml/kg body weight; flow rate: 0.35 ml/s). Postsurgical hypertrophic scar tissue showed definite contrast enhancement, whereas disc herniation remained unenhanced. Intravenous contrast application is recommended in patients previously operated upon for disc herniation.

Cicatrix↗

PubMed1986

[Magnetic resonance tomography of intracranial tumors: use of contrast media versus T2-weighted tomograms].

Nuclear magnetic resonance tomography was performed on 38 patients with intracranial tumours, before and after the administration of contrast, using a 0.35 T Magnetom. The MR examinations included various plain spin-echo sequences (SE 400/35, 800/35, 1600/35, 1600/70, 1600/105, 1600/120) as well as examinations after the iv-administration of gadolinium-DTPA (SE 800/35). On all occasions, the abnormalities were visible without contrast. Differentiation of tumour and its surroundings was possible in 19 out of 38 cases without contrast. Delineation of expansively growing tumours (eg. meningiomas) was possible in twelve out of 14 cases, but in only seven out of 24 cases with infiltrating tumours (eg. glioblastomas). On the other hand, clear differentiation between tumour and adjacent edema and normal brain, respectively, was possible in 35 out of 38 cases after Gadolinium-DTPA.

Adult↗

PubMed1986

Magnetic resonance imaging of intracranial tumors using gadolinium-DTPA. Initial experience with fast imaging.

One hundred and fifty gadolinium(Gd)-DTPA studies in patients with intracranial tumors were performed. In meningiomas (n = 37) Gd-DTPA is useful to delineate isointense tumors. In acoustic neuromas (n = 16) Gd-DTPA helps to identify intracanalicular tumor tissue. In pituitary adenomas (n = 16) para- or suprasellar tumor extension can be better appreciated after Gd-DTPA injection. In glioblastomas (n = 23) Gd-DTPA provides data on differential diagnosis through the characteristic shape of enhancement. In a variety of tumor types the high contrast between enhancing tumor tissue and adjacent structures facilitates therapy planning. Fast imaging sequences now allow for dynamic Gd-DTPA studies. The time-course of enhancement may increase specificity of magnetic resonance imaging.

Brain Neoplasms↗

PubMed1985

Application of contrast agents in CT and MRI (NMR): their potential in imaging of brain tumors.

21 patients with clinical and CT diagnoses of intracranial tumor were studied by MRI (NMR) prior to and after administration of intravenous Gadolinium-DTPA. Resultant MRI images were compared with corresponding CT sections with respect to lesion detection, contrast enhancement, tumor delineation and visualization of perifocal edema. All intracranial lesions shown on CT were identified on MRI. Contrast enhancement in MRI images was achieved in 19 out of 21 patients, as it was also with CT. In these cases improved differentiation between tumor, perifocal edema and adjacent brain structures were obtained. In most cases sufficient visualization of perifocal edema in MRI required T2 weighted images (SE 1600/70) in addition to spin echo scans routinely performed prior to and after contrast medium (SE 400/30 or 800/30). No side effects were encountered following administration of Gadolinium-DTPA. The good tolerance and the efficacy justifies the use of Gadolinium-DTPA for contrast enhanced MRI imaging.

Adult↗

PubMed1985

Initial clinical evaluation of gadolinium DTPA for contrast-enhanced magnetic resonance imaging.

Gadolinium DTPA was evaluated as an intravenous contrast agent for magnetic resonance imaging in 15 patients with primary or secondary intracranial neoplastic disease. T1 and T2 weighted images were obtained prior to contrast administration. T1 weighted spin echo 35/800 (TE/TR) images were utilized to detect enhancement. The increase in signal intensity observed, identifying areas of breakdown of the blood-brain barrier (BBB), was similar in magnitude to the contrast enhancement observed on CT. This permitted differentiation of neoplastic tissue from surrounding cerebral edema on MRI. Direct visualization of otherwise "isomagnetic" lesions was also demonstrated. The use of intravenous contrast media should significantly extend the diagnostic potential and specificity of magnetic resonance imaging.

Brain Edema↗

PubMed1985

[Measurement of regional cerebral blood flow as a supplement to carotid angiography in assessing cerebrovascular insufficiency].

The examination of 91 patients was undertaken in order to establish the relevance of tomographical measurement of the regional cerebral blood-flow, following inhalation of 133Xenon, as a complementary method to the conventional carotis-angiography. In many cases the findings revealed a more precise or even deviating judgement on the hemodynamic relevance of stenosis and obliteration than was proved only by angiography. Especially in the stages I and IV of cerebrovascular disease of the a. cerebri anterior, a. carotis interna and a. carotis communis the rCBF-measurement seemed to be an important parameter for the decision between conservative and surgical therapy as a prognostic parameter for the individual risk of many patients to suffer a cerebral infarction.

Carotid Arteries↗

PubMed1985

[Spondylolysis and -listhesis. A computed tomographic differential diagnosis of lumbar discopathy].

Spinal CT scans of 680 patients with suspected disc herniation were reviewed to detect lumbar spondylolysis. In this group of patients, 3.23% (n = 22) had pars interarticularis defects at L4 or L5. Disc herniation at the interspace of the pars defect was seen in 27.27% (6/22) of patients with spondylolysis. Using Meyerding's method, which measures the degree of vertebral forward dislocation, grade 2 and grade 3 spondylolisthesis were most often seen. While moderate and severe spondylolisthesis can be already detected via lateral localiser image (scout view), pars defects with only little forward dislocation can be easily underdiagnosed. Sources of diagnostic error are: 1. an atypically posterior disc margin which extends beyond only one vertebral body and presents the appearance of disc herniation, 2. pars defects simulating the adjacent facet joints involve the risk of overlooking spondylolysis, 3. CT sections made through the intervertebral discs and facet joints only, may fail to show up the pars defect 10 or 15 mm above the disc plane.

Adolescent↗

PubMed1985

Brain tumors: MR imaging with gadolinium-DTPA.

Magnetic resonance (MR) imaging was performed on 40 patients with intracranial tumors, before and after intravenous administration of gadolinium-DTPA (Gd-DTPA). Precontrast studies included a comprehensive protocol of spin-echo sequences. Tumors were visualized on precontrast images either directly or indirectly by anatomic distortion caused by the mass. However, differentiation of the tumor from adjacent tissues was possible in only 17 of 40 cases. Delineation of the tumor was best on precontrast, T2-weighted images. After administration of Gd-DTPA (0.1 mmol/kg), increased signal intensity from the tumor was observed in all patients. The localized increase in signal intensity in the tumor considerably improved the tumor delineation in 36 of 40 patients. Whereas most of the meningiomas, neuromas, and adenomas could be delineated prior to administration of contrast material if appropriate pulse sequences were applied, glioblastomas and intracranial metastases required Gd-DTPA administration for diagnostically sufficient tumor display.

Adenoma↗

PubMed1985

Pelvimetry by digital radiography and its dosimetry.

Sonography is firmly established in obstetrics as the method of choice for the localization of fetus and placenta. However, for the determination of pelvic dimensions sonography does not suffice. Thus, for a few strictly selected indications conventional x-ray pelvimetry is used. This has the disadvantage of the relatively high radiation dose for the fetus and the maternal gonads. Since the introduction of digital radiography, there is the alternative of digital pelvimetry. We performed dosimetry comparing digital and conventional radiography with the new high amplifying screens (Quanta III, Dupont) using an ionization dosimeter and a wax phantom. The radiation dose of digital radiography was 24 mu Gy. This corresponds to about 15% of a comparable conventional exposure (177 mu Gy). A further advantage of digital radiography is a standardized and rapid exposure technique; furthermore pelvic dimensions can be measured directly. The disadvantages are the poorer spacial resolution and poor image quality in obese patients. Digital radiography because of its lower radiation dose is suitable for pelvimetry for special indications.

Computers↗

PubMed1985

[Computed tomographic and nuclear spin tomographic diagnosis of brain tumors using conventional and paramagnetic contrast media].

52 patients with cerebral tumours were examined by both CT and MR. Contrast media containing iodine were used in CT, whereas in MR a paramagnetic contrast medium (gadolinium-DTPA) was applied by IV injection. A comparison of CT and MR findings showed that with both methods it was often not possible to achieve sufficient visualization and delineation of tumour tissue without employing a contrast medium. After application of the contrast medium, the shape and size contrast enhancement in the tumour tissue in both CT and MR was practically identical. This enables direct visualization of the tumour, superior delineation from the adjacent tissue, and differentiation between oedema and tumour, resulting in effective treatment planning which would otherwise not be possible.

Aged↗

PubMed1984

[Comparison of computed tomography, automated multisector scanner (Octoson) and conventional ultrasound in pancreatic diseases].

Two hundred and eighty-six patients suspected of having pancreatic disease were examined by computed tomography, Octoson and conventional ultrasound. Computed tomography with angio-CT had the highest sensitivity (87.4%). The Octoson, with a sensitivity of 77.16% was better than conventional ultrasound, which had a sensitivity of 65.35%. Specificity for CT was 91.2%, for the Octoson 88.67% and conventional ultrasound 85.5%. The better results of the Octoson examination are due to the thin air gap when the patient is prone and the greater focal length of the large transducer and the somewhat more stable focus.

Acute Disease↗

PubMed1984

[Human testing of the nuclear spin tomographic contrast medium gadolinium-DTPA. Tolerance, contrast affect and the 1st clinical results].

In an initial clinical trial we examined the tolerance and the influence exercised on signals in nuclear magnetic resonance tomography by gadolinium-DTPA. In an open study, 4 dosages between 0.005 and 0.25 mmol Gd-DTPA/kg body-weight were tested on 5 healthy volunteers each. To ensure renal elimination of Gd-DTPA, NMR images were produced (0.35 T Magnetom) visualising the kidneys and urinary bladder before and more than 60 minutes after application of the contrast medium. The article shows in what manner the image is influenced by the dosage of the contrast medium and also by the time interval elapsing between injection of the contrast medium and production of the NMR tomogram. - Finally, first clinical results of NMR tomography contrast medium application are demonstrated in the case of 5 patients with cerebral tumours.

Adult↗

PubMed1984

[Intravenous administration of contrast medium during computed tomography (CT) of the operated lumbar spine].

In 35 patients with recurrent radicular complaints which occurred 4 weeks to 38 months after operation for lumbar disc herniation, the degree of contrast enhancement of hypertrophic scar tissue was examined. All patients were scanned before and immediately after intravenous contrast application (volume: 1.5-2.0 ml/kg body weight, flow rate: 0.35 ml/sec). In 83% of the cases hypertrophic scar tissue did show definite contrast enhancement, whereas disc herniation remained unenhanced. Comparison between contrast enhancement and age of scar tissue produced poor correlation (r = 0.3012) with older scarring showing a trend towards lower enhancement levels. In cases where morphologic and topographic criteria in plain CT examination fail to yield a diagnosis, intravenous contrast application is recommended. Our data indicate that even those patients might benefit from the procedure who have been operated upon for disc herniation several months or years ago.

Adult↗

PubMed1984

[Focal liver diseases. Comparative study of computed tomography, conventional ultrasound and the automated multisector scanner (Octoson)].

A comparative study, on 251 patients, between CT, Octoson and conventional ultrasound, established that CT (with angio-CT) had the highest rate of sensitivity (95.86%). The Octoson examination had a higher sensitivity (92.58%) than the conventional ultrasonic examination (82.64%). This result is achieved because superficial and subdiaphragmatic metastases, which lie in the depth of the liver, are better presented by the Octoson than with a mechanical sector scanner. Superficial metastases need to be presented with a water-path transducer for superficial lesions and subdiaphragmatic metastases with a wide range focus transducer. These areas can also be accurately shown on scanners with a dynamic transducer. The specificity of these three methods lies between 90 and 96%.

Echinococcosis, Hepatic↗

PubMed1984

[Nuclear magnetic resonance tomography in space-occupying kidney lesions].

The kidneys in 15 patients (8 renal tumours, 4 cysts and 7 normal patients) were examined by means of super-conductive NMR tomography in order to assess the value of the method and its use in tumour staging. The findings were compared with computed tomography, angiography and surgery. Parenchymal tumours and cysts are easily recognised and differentiated, as they are on CT. NMR demonstrates a pseudo-capsule, which can otherwise only be seen on the angiogram, or on angio-CT. The extent in the peri- and pararenal space, infiltration into neighbouring organs and lymph nodes are equally well seen on NMR and CT. NMR equals angiography for demonstrating invasion into the renal vein and vena cava and, in this respect, is better than CT.

Adult↗

PubMed1984

[Computed tomographic staging of hypernephroid carcinoma].

In 68 patients with renal cell carcinoma computed tomographic staging was compared to the histopathologic staging. The classification based to the staging scheme developed by Robson. The CT criticized the tumor stages correctly in 82%. Consequently CT is superior to angiography, especially in detecting infiltration of the peri- and pararenal space and of lymph node metastases. Difficulties were found in detecting tumor extension into the renal vein near by the renal hilus.

Adult↗

PubMed1984

[Nuclear spin tomographic diagnosis of brain tumors using the contrast medium gadolinium-DTPA].

This study examines the effect of the NMR contrast medium gadolinium-DTPA on image contrast in cerebral tumours. Sixteen patients with space-occupying cerebral lesions were examined on a 0.35 Tesla superconducting scanner, using a T1-weighted spinecho sequence prior to and after the intravenous application of gadolinium-DTPA. In 8 patients T2-weighted spinecho-sequences were obtained before the administration of contrast. The tomograms were evaluated visually and according to quantitative criteria. The use of gadolinium-DTPA helps to evaluate the blood-brain barrier and improves diagnosis by differentiating tumour tissue from edema and from normal brain tissue.

Adult↗

PubMed1984

Pharmacokinetics of ethynyl estradiolsulfonate in minipigs.

The pharmacokinetics of ethynyl estradiolsulfonate labelled with 3H in the steroid nucleus and with 14C in the isopropylsulfonic acid side chain was investigated in male minipigs. The plasma level after intravenous administration was interpreted according to a three-compartment model. After oral administration the first two phases were overlapped by the absorption period. The renal and fecal excretion of the two labellings were investigated. In urine the majority of the 3H-labelled steroid was excreted in the unconjugated and in the glucuronide fractions. More than 70% of 14C in urine was unextractable.

Administration, Oral↗