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Biomedical subjects

M Thelen

Publications and source records attributed to M Thelen.

At least 253 records · Page 14Linked to original sources
PubMed1993

[Magnetic resonance tomography of chronic aortic dissection].

17 patients with chronic aortic dissection were examined by MRI. In 12 patients, comparison between gradient echo sequences and SE sequences was possible. Gradient echo sequences, unlike SE sequences, permitted evaluation of flow in the true and false lumen, reliable differentiation between thrombus and flowing blood and clear delineation of the intimal flap. An additional comparison between transoesophageal ultrasound and MRT in 15 patients showed significant advantages in favour of MRI. In three patients MRI was able to detect more proximal origins of the dissection. Moreover, MRI allowed evaluation of the major aortic branches and their relation to the dissection; this was not possible with ultrasound. MRI plays an important role in the follow-up of chronic aortic dissections.

Adult↗
PubMed1993

[Computed tomography following extracorporeal shockwave lithotripsy of the kidneys. III. A prospective CT study of 105 patients and a 3-year follow-up of 23 patients using CT and 99mTc-MAG3 clearance].

In 105 patients CT studies were done prospectively after renal ESWL with a second generation lithotripter. 33 (31%) of the patients had renal oedema (n = 8), renal (n = 20) or extrarenal (n = 31) bleeding. Three of the 23 patients who had a three year follow-up had chronic renal changes, 10 had renal stones. As blunt renal trauma can be the cause of renal hypertension a longterm follow-up is necessary in ESWL patients, particularly if there was renal bleeding after treatment. Further studies are needed to determine the exact risk of renal hypertension after ESWL.

Adult↗
PubMed1993

[Retrograde venous occlusion--therapy of impotence of venous origin].

Retrograde occlusion of penile drainage veins can produce improvement in patients with impotence due to venous leaks. We performed 50 transfemoral and three transjugular procedures; 46 (86%) were technically successful. Clinical improvement was found in 24 out of the 46 procedures (52%). In 20 patients spontaneous intercourse became possible, in four this occurred after intracavernous injection of vaso-active substances. In eleven patients there was deterioration after one to twenty months; in seven this was treated by repeated venous occlusion. In 13 patients improvement has been maintained over a period of one to thirty months (average 10.5 months). There were no complications.

Angiography↗
PubMed1993

[MR tomographic functional analysis of the left ventricle].

The following contribution presents a continuous MRT analysis of the contraction and relaxation processes of healthy left ventricles giving reference values for contraction and relaxation velocities. For the total ventricle we have Vsyst. r. total = 342 +/- 47% LVEDV/sec and Vdiast. r. total = 303 +/- 59% LVEDV/sec. In relation to the end-diastolic (tomographic) volume (EDSV) significantly greater changes in volume per unit of time were measured apically compared to basal (systolic: 411 +/- 89% EDSV/sec apical vs 261 +/- 35% EDSV/sec basal; diastolic: 810 +/- 145% EDSV/sec apical vs 245 +/- 70% EDSV/sec basal). Occurrence of the end-systolic minimal volumes of apical tomographic layers was delayed against the total ventricle by 22.4 +/- 7.9% t syst. Within the ventricle there was systolically a redistribution of the proportions of volume from apical to basal.

Adult↗
PubMed1993

[MR tomographic measurement of the diastolic relaxation of the hypertrophied left ventricle with the single-slice-multiphase technic].

In order to assess diastolic ventricular function in hypertensive patients, a single-slice multiphase sequence was used in order to measure contraction and early diastolic relaxation. There was no difference in the contraction velocity between hypertensives and normals (Vsys. n.r. = 56.1 +/- 13.8% LVDV/s vs. 51.7 +/- 8.6% LVEDV/s, stat, n. sign.). Early diastolic relaxation velocity in hypertensives was reduced as compared with the control group (Vdiast. 1n.r. = 37.9 +/- 13.1% LVEDV/s vs. 47.1 +/- 9.6% LVEDV/s, p < 0.05). There was no linear relation between abnormal relaxation and the extent of myocardial hypertrophy. Hypertensives with myocardial hypertrophy frequently had reduced early diastolic relaxation velocity. Regression analysis for estimating left ventricular volumes derived from single-slice measurements were confirmed by additional multislice measurements. The calculated LVEDV correlated at r = 0.956 with multi-slice measurements and tended to show lower values (LVEDV n.r. = 104.6 +/- 30.8 ml vs. LVEDV = 102.1 +/- 28.8 ml, r = 0.956, p < 0.05). The LVESV was overestimated by the multi-slice technique, the calculated regression volume averaged 23% lower, realistic values (LVESV n.r. = 28.5 +/- 15.3 ml vs. LVESV = 37.1 +/- 15.6 ml, r = 0.887, p < 0.001).

Adolescent↗
PubMed1993

[Motility disorders of the esophagus--their diagnosis with a rice-barium meal].

UNLABELLED: The purpose of this study was to evaluate the role of a "barium-rice" study for diagnosis of dysphagia and oesophageal motility disorders. MATERIAL AND METHODS: 203 patients with oesophageal motility disorders of various aetiologies were examined by both conventional barium study and a "barium-rice" study. During the latter, oesophageal clearance of a defined mixture of barium sulfate and boiled rice was measured. RESULTS: The conventional barium study revealed prolonged transit time in only 15.8% (32 of 203 cases), whereas barium-rice study was pathological in 50.8% (103 to 203 cases). In 71 of 171 patients (41.5%) with a normal barium study, barium-rice passage was prolonged. In 23 patients, radiological results were confirmed by manometric measurements. CONCLUSION: Oesophageal motility disorders are detected by a barium-rice study with high sensitivity independent of the underlying disease. The barium-rice study offers a simple diagnostic tool revealing quantitative and reliable results. The barium-rice study is a suitable method for screening and follow-up of patients with dysphagia and oesophageal motility disorders.

Adolescent↗
PubMed1993

[Diagnosis and follow-up of tumors and metastases of the liver using imaging techniques].

Sonography, CT, angiography, MR and methods of nuclear medicine are used in imaging for diagnostic purposes. Only few intrahepatic benign or malignant tumors can be safely diagnosed by a single method on the basis of their characteristic pattern. However, a meaningful combination of certain methods enables improved differential diagnostic identification of focal hepatic lesions. If uncertainties remain, the diagnosis can be confirmed by means of a histological examination supported by imaging methods. The authors describe typical patterns of manifestation of hepatic tumours and critically review the fundamental value and ranking of diagnosis of primary and secondary malignant tumours of the liver.

Angiography↗
PubMed1993

[The importance of imaging techniques in gallstone disease].

The available surgical and non-surgical therapy options for treatment of gallstone disease are presented. Conventional cholecystectomy is regarded as standard therapy of symptomatic cholecystolithiasis. Other modes of therapy may be indicated under certain circumstances, depending on the results of imaging procedures. In this context conventional X-ray examination, oral and intravenous cholecystography, sonography, computed tomography, endoscopic retrograde cholangiography/cholecystography, and magnetic resonance imaging are discussed and their influence on therapeutic decisions is explained.

Cholangiopancreatography, Endoscopic Retrograde↗
PubMed1992

MARCKS is an actin filament crosslinking protein regulated by protein kinase C and calcium-calmodulin.

AGONISTS that stimulate protein kinase C (PKC) induce profound changes in cell morphology correlating with the reorganization of submembranous actin, but no direct connection between PKC and actin assembly has been identified. The myristoylated, alanine-rich C kinase substrate (MARCKS) binds calmodulin and is a predominant, specific substrate of PKC which is phosphorylated during macrophage and neutrophil activation , growth factor-dependent mitogenesis and neurosecretion; it is redistributed from plasma membrane to cytoplasm when phosphorylated and is involved in leukocyte motility. Here we report that MARCKS is a filamentous (F) actin crosslinking protein, with activity that is inhibited by PKC-mediated phosphorylation and by binding to calcium-calmodulin. MARCKS may be a regulated crossbridge between actin and the plasma membrane, and modulation of the actin crosslinking activity of the MARCKS protein by calmodulin and phosphorylation represents a potential convergence of the calcium-calmodulin and PKC signal transduction pathways in the regulation of the actin cytoskeleton.

Actin Cytoskeleton↗
PubMed1992

[Ultrasound-proven adrenal gland tumor. References for diagnostic management].

Due to the increasing number of ultrasonographic examinations, tumors of the adrenal glands are being detected more and more often. In the present paper, suggestions for the further diagnostic evaluation are made: in the case of sonographically detected solid tumors of the adrenals, computed tomography is the next procedure of choice. If CT scan also fails to enable an unequivocal diagnosis, the next step must be laboratory investigations. Hormone-producing tumors, irrespective of size, as well as non-hormone-producing tumors larger than 6 cm in diameter or symptomatic neoplasms are all treated by surgery. In the case of an oncological patient with an asymptomatic non-hormone-producing tumor, differential diagnosis via needle aspiration should be attempted in all tumors measuring less than 6 cm in diameter. In the event of an incidental finding, fine needle aspiration is performed only in lesions measuring between 4 and 6 cm; for tumors of less than 4 cm, we consider a wait-and-see approach, with follow-up examinations at 3-month intervals to be justified.

Adrenal Gland Neoplasms↗
PubMed1992

[MR tomography in testicular processes. The significance of Gd-DTPA enhanced sequences in comparison with plain T2-weighted sequences].

The value of T1-weighted sequences after intravenous administration of Gd-DTPA and of T2-weighted sequences was compared in 43 patients suspected of having scrotal abnormalities. T2-weighted sequences gave better demonstration of the tunica albuginea and better contrast between tumor and parenchyma. The two techniques were equally sensitive for demonstrating testicular tumors but orchitis was better demonstrated on the contrast enhanced sequences. Motion artifacts were less marked in the T1-weighted sequences with contrast enhancement. In selected cases, contrast enhancement may be a valuable addition to native protocols. Our experience has indicated that MRI provides specific findings in cases of orchitis which are clinically atypical; this facilitates the decision to conservative treatment and prevents unnecessary exploration of the testes.

Adolescent↗
PubMed1992

[MR tomography of injuries of the medial collateral ligaments of the knee joint].

Frequency and characteristics of lesions of the medial collateral ligaments (MCL) were studied by MRI in 155 patients with trauma to the knee. There were abnormalities of the MCL in 38% of cases with ligamentous injuries and in 27% these were combined with meniscal tears. 11% of these patients showed isolated rupture of MCL and as a result of the MRI findings were treated conservatively. By means of T2*-weighted images the individual lesions could be accurately localised. Characteristic findings have been defined.

Humans↗
PubMed1992

[Cystic space-occupying lesions of the seminal vesicles. Their demonstration with MRT].

Between October 1990 and March 1991, 8 patients with cystic lesions in the region of the posterior bladder wall, the seminal vesicles and the prostate were examined by MRI. In all cases there was accurate characterisation of the lesion and of its anatomy. In 3 patients with abnormalities in the retrovesical space there was very good agreement with the operative findings. 4 patients were treated conservatively. In these patients there was good agreement with the findings on cystoscopy, CT and sonography.

Adult↗
PubMed1992

[Measurement error estimation in MR tomographic volumetry of the left ventricle with the multisection technic].

A multi-slice technique for MRT measurements of the left ventricular volume is much faster than the use of single-slice methods and is therefore better tolerated, leaving time for additional measurements. The end-diastolic left ventricular volume can be reliably measured by this method (123.3 +/- 13.5 ml vs. 124.1 +/- ml). The end-systolic volume is consistently overestimated by 23.7 +/- 18.3% compared with the reference value obtained by single slice measurements (47.9 +/- 8.9 ml vs 39.1 +/- 7.9 ml). Correspondingly, stroke volume and ejection fraction is underestimated on average by 10.6 +/- 9.7% and 10.6 +/- 7.6% respectively).

Adult↗
PubMed1992

Dissection following balloon angioplasty of aortic coarctation: review of the literature.

Balloon angioplasty of the coarctation of the aorta can result in intimal or medial or even adventitial dissections as demonstrated by in vitro studies and animal experiments. As a typical sign of stretching of the aortic wall, patients complain of pain during the angioplasty procedure. In the literature, aortic wall rupture and ventricular fibrillation during the procedure are reported. Additional sudden deaths can occur within 40 hours after the procedure. Mortality ranges from 0.1% to 2.5%. By transesophageal echocardiography, monitoring of balloon angioplasty, control of the positioning of the balloon, and control of the results and detection of complications are possible. Intimal as well as medial dissections can be detected with observed healing for intimal but also medial dissections. In order to avoid the patient's discomfort, intraaortic ultrasound will be used in the future, when major methodological improvements are done. Computed tomography demonstrates medial dissections but is not able to visualize intimal dissections. Using computed tomography and magnetic resonance after angioplasty of the coarctation of the aorta, irregularities are described in up to 17% of the patients. For angiography, a low detection rate of medial dissections has to be expected, when not biplane angiographies of the whole thoracic aorta are performed. Medial dissections can be seen, but intimal dissections are missed. In conclusion, a review of the literature demonstrates a high incidence of intimal and medial dissections after angioplasty of the coarctation of the aorta with spontaneous healing in most patients. As is the way with coronary angioplasty, aortic wall ruptures are rare, but stand-by surgery is necessary.

Aortic Dissection↗