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Biomedical subjects

M Thelen

Publications and source records attributed to M Thelen.

At least 235 records · Page 13Linked to original sources
PubMed1994

[Gadolinium-DTPA (Magnevist) as contrast medium for arterial DSA].

16 DSA investigations using intra-arterial Gd-DTPA were performed on 12 patients. The contrast medium was administered either as a 0.5 molar gadolinium solution (commercially available) or diluted with distilled water to a 0.2-0.4 molar gadolinium solution. The injection was made either by pressure injector or by hand. The aortic arch, abdominal aorta and pelvic and lower limb arteries were examined. 14 of the 16 procedures were diagnostically adequate, but compared with iodinated contrast materials, contrast was less marked. There were no cardiovascular, neurological or allergic side effects. Three patients suffered a feeling of heat and one patient had mild pain during the injection. Even large volumes rapidly injected (up to 20 ml/s of the commercially available solution) were well tolerated. DSA with intra-arterial Gd-DTPA seems to be a suitable alternative for vascular imaging if iodine-containing contrast materials are contraindicated.

Angiography, Digital Subtraction↗
PubMed1994

[Computed tomography of the kidneys following tumor enucleation].

Two weeks to 120 months after enucleation of renal tumours the postoperative defects were correctly localized by renal computed tomography in 34 patients. Typical defect morphology was either wedge-shaped or concave. No dependence on tumour localization, tumour size, operative technique or a certain surgeon was observed. The cortical defects were smaller (mean 2.0 cm) than the original, prominent tumours (mean 3.4 cm). In small defects without tension suture of the capsule is sufficient, leading to minor defects. Larger defects were closed with a retroperitoneal or free peritoneal fat flap resulting in larger residual defects. In case of intra- or postoperative bleeding, CT could demonstrate parenchymatous or perirenal haematomas or delayed perfusion of adjacent parenchyma. In one patient a recurrent tumour was correctly diagnosed, different postoperative complications (such as abscesses) were not observed.

Adenoma, Oxyphilic↗
PubMed1994

[1H-MR spectroscopic imaging: an approach to evaluating alcohol breakdown in the brain].

The local alcohol concentration in the human brain was determined in 10 cases using MR spectroscopic imaging. Therefore 7 subjects with an average blood alcohol concentration of 0.8/000 were examined after oral intake of alcoholic beverages. Varying alcohol concentration was found intracranially which was recorded spectroscopically w.r.t. time. Relatively high ethanol concentrations were determined in the cerebellum as well as in the ventricular system. Contrary to this, lower concentrations were found in the regions of grey and white matter.

Adult↗
PubMed1994

[The aftercare of breast carcinoma. The value of plain thoracic radiography, abdominal sonography and mammography].

7865 follow-up examinations were performed on 420 patients who had had surgery for carcinoma of the breast; there were 2755 radiographs of the chest, 2660 sonographic examinations of the upper abdomen and 2450 contralateral mammograms. The most common findings were metastases seen on the chest radiographs during the 13-24 and 25-60 months intervals in 4.7% of cases. The incidence increased with initially higher tumour stages and in ductal carcinomas. Sonography of the upper abdomen showed 4.3% of liver involvement, mostly between the second and fifth year; this was independent of tumour stage or the histology of the primary tumour. Positive mammography of the contralateral breast was found in 3% within the first three months after surgery. A contralateral carcinoma was more common in case of lobular primary tumours. There was no direct correlation with the initial tumour stage. We evaluated the routine use of these imaging procedures as part of the follow up of carcinoma of the breast in relation to the additional cost.

Abdomen↗
PubMed1994

[In vitro NMR spectroscopy of healthy, pathologically changed and carcinomatous breast tissue samples correlated with histological findings].

Of 57 patients with clinically suspected mamma carcinoma 121 samples were analysed by in vitro 1H-NMR spectroscopy at 300 MHz and correlated with histological data. Within the relevant spectral region between 2.7 and 4.1 ppm strong signals were observed from fat, (phosphoryl-) choline, (phospho-) creatine, and carnitine. Furthermore, with high regularity, 8 weak, partly overlapping signals were resolved and attributed to glucose, glycine, threonine, serine, inositol, and sucrose. Their intensities were determined by an iterative fitness program. From the intensity ratios, different kinds of tissue could be distinguished based on spectroscopic criteria. Healthy or mastopathically modified tissue could be discriminated from more than 50% carcinoma affected tissue with a specificity of better than 99.5%. This fact is explained by the lower content of fatty acids in the malignant tissue. Differences between spectra of healthy of mastopathically affected tissue were only small.

Breast↗
PubMed1994

[Spiral computerized tomography of the breast].

AIM: To evaluate the use of spiral CT in the diagnosis of breast lesions. MATERIAL AND METHODS: 93 female patients with suspicious or uncertain mammographic findings were examined by CT before and after contrast enhancement according to the following practical method: table movement, 6 mm/s, slice thickness 6 mm, increment 4 mm, contrast 200 ml, injection rate 3 ml/s, scan start 50 s after the beginning of the injection. Histological confirmation was present in 85 patients. RESULTS: All 44 invasive carcinomas were recognised. They were characterised by intensive focal contrast uptake. Only 2 out of 7 intraductal carcinomas were not shown by CT. 36 out of 38 benign lesions were correctly diagnosed. 2 out of 11 fibroadenomas showed strong enhancement and were incorrectly diagnosed. The examinations provided valuable additional information compared to mammography and sonography. CONCLUSION: Spiral CT is very useful for elucidating problems in the diagnosis of breast lesions. Its advantages consist in the speed of the method, comfort for the patient, absence of movement artifacts, easy standardisation and wide applicability.

Adenocarcinoma, Mucinous↗
PubMed1994

[Comparison of the value of angioscopy, angiography and ultrasonography in detection of pathologic vascular processes].

AIMS: The ability of angioscopy, angiography and sonography to evaluate arteriosclerotic vascular lesions were compared to determine if angioscopy is a valuable addition in the diagnostic armamentarium. METHODS: An in-vitro study was selected to enable microscopic assessment of the arteries. Angiography was followed by sonography and endoscopy and finally the vessels were evaluated macro- and microscopically. RESULTS: The configuration of the vascular stenosis (plaque-shape, semicircular-eccentric, circular-concentric) was more reliably defined with angioscopy as compared to angiography and sonography. Intense calcification of plaque was detected sonographically with a high sensitivity (90%) using the acoustic shadowing and high amplitude criteria. Angioscopy was superior in differentiating between simple and complicated plaques and the assessment of ulcerations, while the visualization of the entire vascular tree with potential collaterals remained the domain of angiography. CONCLUSIONS: Angioscopy seems to be valuable addition in the evaluation of arterial vascular disease. It can be used in the quality control after interventional radiology and surgery.

Angiography↗
PubMed1994

Pulmonary arteries and lung parenchyma in chronic pulmonary embolism: preoperative and postoperative CT findings.

PURPOSE: To evaluate the role of computed tomography (CT) in diagnosis of chronic thromboembolic pulmonary hypertension, assessment of surgical operability, and follow-up after surgery. MATERIALS AND METHODS: Seventy-five patients with chronic thromboembolism were examined with CT; 63 underwent thromboendarterectomy, and postoperative CT scans were acquired in 23. CT scans were analyzed for vascular and parenchymal changes, and findings were compared with those on lung scintigrams and with surgical results. RESULTS: CT findings allowed confirmation of the diagnosis of chronic thromboembolism and ensured technical operability (sensitivity, 77%; specificity, 100%; overall accuracy, 80%) by means of direct visualization of thrombi in central pulmonary arteries in 53 patients. CONCLUSION: CT enables demonstration of pulmonary thromboembolism with criteria pertaining to pulmonary arteries and to lung parenchyma and enables assessment of technical operatibility and confirmation of surgical success.

Adult↗
PubMed1994

[Computerized tomography in diagnosis of lung metastases: improvement with the spiral technique].

Computed tomography is the imaging modality of choice for detection or exclusion of pulmonary metastases. In most cases these are spheric, multiple, bilateral, and located in the peripheral areas of the middle and lower fields of the lungs. Differential diagnosis of solitary pulmonary nodules is difficult. Evaluating whether they are malignant or benign is insufficient despite the application of multiple CT criteria. Spiral computed tomography acquiring an imaging volume in a breathhold has led to significant improvement in the sensitivity of detecting pulmonary nodules. Imaging protocols are presented, and the influence of the different parameters is discussed. Although not all pulmonary metastases may be detected with spiral computed tomography, it is the most important examination when considering pulmonary metastasectomy. Computed tomography is the imaging modality of choice when monitoring pulmonary metastases during systemic therapeutic regimens by measuring all nodules or "indicator lesions."

Diagnosis, Differential↗
PubMed1994

[CT and MRT of the paranasal sinuses].

The updated minimally invasive surgical methods used in chronic sinusitis require accurate and anatomically detailed preoperative diagnostics. Conventional x-rays cannot satisfy these increasing diagnostic requirement, since this method images a complex three-dimensional anatomy and pathology by means of a two-dimensional summation take. Both CT and MRI have a high resolution of contrast and site and assure visualization that is free from superimpositions. Both methods, however, differ from one another in respect to principles of technique and in characteristics; in this regard, the imaging of bone by MRI is always hypointense, which is a major drawback. Hence, for clarifying the identification of chronic sinusitides, in the diagnosis of suspected chronic sinusitis, CT is the method of choice. Besides the typical presentation of normal anatomy and anatomical variations, pathological findings are demonstrated.

Humans↗
PubMed1993

[Carbon dioxide--contrast medium for digital subtraction angiography].

UNLABELLED: Fundamental considerations: Despite appreciable improvements in conventional iodine-containing contrast media, vascular studies involving patients with renal insufficiency, hyperthyroidism or known allergic reaction to conventional contrast media continue to pose a problem. Own study: Testing the investigation of the possibility of visualizing vessels using carbon dioxide as a gaseous contrast medium. In 30 patients, angiography of the pelvis and legs (DSA) employing conventional iodine-containing media and/or CO2 were carried out simultaneously. RESULTS, handling and toleration were compared. In two further patients, percutaneous transluminal angioplasty and stent implantation, respectively, were successfully performed under CO2 control. RESULTS: All the findings obtained with "normal" DSA were also obtainable with CO2. The CO2 examination, however, was often plagued by incomplete contrasting of the blood vessels, with interruption of the contrast medium column, which made assessment more difficult. In two of the 30 patients undergoing angiography of the pelvis and legs, the investigation had to be abandoned on account of persistent intensive lower abdominal pain under CO2 injection.

Angiography, Digital Subtraction↗
PubMed1993

[Angiography in infancy and childhood].

Between 1973 and 1991 we performed 160 percutaneous angiograms (130 arteriograms, 30 phlebograms) in children and infants; 12 patients were less than one year and 52 less than ten years old. 44 of the examinations were done by a DSA technique. The examinations were carried out under general anaesthesia except in 8 cases. In 50.7% an arteriogram was carried out for the investigation of a suspected or known tumour, in 9.3% an arteriogram was required following trauma. The most common phlebographic examination was for the demonstration of the spermatic vein; in 27 patients this was done for cryptorchidism or a varicocele. The only complication following a diagnostic angiogram was perforation of one spermatic vein. There were no other complications requiring treatment, such as thromboembolic events. With a total complication rate of 0.6%, angiography in childhood is a relatively safe diagnostic method.

Anesthesia, General↗
PubMed1993

[Spiral CT with three-dimensional (3D) surface reconstruction in assessing solitary pulmonary foci].

Recently it has been thought possible to characterise a pulmonary lesion by its vascular involvement. The complex vascular relationships are difficult to demonstrate by the "normal" technique of transverse CT sections. Spiral CT with 3D-surface reconstruction makes it possible to evaluate the vessels accurately and simulates the appearances one would have by looking into the thorax with a demonstration of all vessels lying within the pulmonary space examined by CT. Venous involvement was shown in every one of 18 malignant lesions but was also found in 4 out of 11 benign lesions, arterial involvement occurred in 14 out of 18 malignant and in 2 benign lesions. CT evidence of vascular involvement is in favour of a malignant tumour but is no absolute proof.

Computer Graphics↗