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Biomedical subjects

G van Kaick

Publications and source records attributed to G van Kaick.

At least 19 recordsLinked to original sources
PubMed1995

[Functional magnetic resonance tomography of movement disorders in patients with schizophrenia].

UNLABELLED: Neurological soft signs (NSS), which are minor motor and sensory deficits, e.g., during finger-to-thumb opposition, are frequently found in schizophrenia. The purpose of this study was to investigate differences in the cerebral activation pattern in ten schizophrenic patients and ten healthy volunteers using functional MRI. METHODS: fMRI was performed using a modified FLASH sequence (TR/TE/alpha = 100/60/40 degrees) and a conventional 1.5 T MR scanner. Color-coded statistical parametric maps based on Student's t-test were calculated. Activation strength was quantified using a 5 x 6 grid over-lay. RESULTS: The volunteers showed a higher activation strength during left hand movement compared to right hand movement. This lateralization effect was reversed in patients who showed overall reduced activation strength. CONCLUSIONS: Disturbed interhemispheric balance in schizophrenic patients during motor task performance can be demonstrated using fMRI. These findings support the hypothesis that changes in the sensorimotor cortex may be involved in the development of NSS.

Adult↗
PubMed1995

[The initial results in the fractionated 3-dimensional stereotactic irradiation of clivus chordomas].

BACKGROUND: The purpose of this study is to determine the impact of fractionated three-dimensional stereotactic radiotherapy on local tumor control and radiation induced side effects in patients with spheno-occipital chordoma. PATIENTS, MATERIAL AND METHODS: 13 patients with chordoma of the clivus (8 female, 5 male, median age at radiotherapy 42 years) were treated with a three-dimensional non-coplanar stereotactic irradiation technique using 15 MeV-photons. Median dose applied was 70 Gy. Irradiation was performed in 2 patients after biopsy and in 11 patients after resection of chordoma (2 R1-resections and 9 R2-resections). RESULTS: After a median follow-up period of 32 months (4 to 80 months) 12 patients are alive (92%). One patient died 4 months after radiotherapy due to tumor progression. Three of the surviving patients developed local recurrence. Until now local tumor control is 69%. In two patients who had macroscopic tumor after surgery a complete regression occurred (verified by CT and MRI respectively). Early radiation complications were moderate, only headache and dizziness were observed. Also late radiation complications were low. Only one patient developed an endocrine dysfunction due to pituitary injury. Ongoing hormone replacement was necessary in this case. No patient developed sequelae of the optic system, cranial nerves or brain stem. CONCLUSION: With regard to local tumor control our results are in the more favorable range compared to the results obtained with conventional photon irradiation techniques. In spite of the high doses applied both early and late radiation complications were in an acceptable range. Further adequate follow-up must prove, whether these promising results will be corroborated in the future.

Adult↗
PubMed1992

New aspects in the staging of lung cancer. Prospective validation of the International Union Against Cancer TNM classification.

BACKGROUND AND METHODS: To validate the new TNM definitions for lung cancer (International Union Against Cancer [UICC] TNM classification, 4th edition, 1987), the data of 3823 patients were analyzed prospectively in terms of concordance between clinical (TNM) and pathologically confirmed classification (pTNM), the value of the various diagnostic techniques in estimating the pathologically confirmed classification, and the prognostic relevance of the new TNM definitions. RESULTS: With regard to the primary tumor (T), clinical and pathologic classifications were identical in 63%; with regard to lymph node involvement (N), the agreement was 47%; for distant metastasis agreement occurred in 91% of cases and for the stages it occurred in 56%. As to the primary tumor (T), the accuracy of radiography (59%) was nearly identical to that of computed tomography (CT) (58%). Both techniques were less precise in determining the extent of lymph node involvement (CT, correct assessments in 50%; radiography, correct assessments in 43%). The statistically significant differences in the prognosis for the T, N, and M categories and for the stages and the categories of the new R classification could be confirmed. Allowance should be made for the different prognosis between T1N0M0 and T2N0M0 by the new Substages IA and Ib of Stage I. CONCLUSIONS: By the new TNM definitions for bronchus carcinoma, international conformity became feasible and practical, and the improvement of its prognostic relevance provided a more reliable basis for establishing guidelines for individual oncologic concepts.

Bronchial Neoplasms↗
PubMed1992

[MR angiography. Its use in pulmonary and mediastinal space-occupying lesions].

MR angiography (MRA) proved to be promising combined to MR imaging (MRI) in the assessment of intrathoracic masses. Sequential FLASH 2D angiograms were acquired in breath-hold technique using the following parameters: TR = 30 ms, TE = 10 ms, FA = 30 degrees. Section thickness was 5 mm with 1 mm overlap between sequential sections. Individual conditions of the examination were achieved by an automatized control procedure. Targeted MIP postprocessing resulted in 3D reconstructions illustrating vascular anatomy and avoiding superimposition. Presentation should be done by cine-mode for better spatial impression. This method was evaluated in a prospective study of 21 patients with malignant pulmonary and mediastinal masses in addition to spin-echo imaging. The diagnostic contribution concerning the relationship between the mass and the vasculature like displacement, stenosis, and poststenotic perfusion defect were assessed.

Adult↗
PubMed1992

Metabolic design of combination therapy: use of enhanced fluorodeoxyglucose uptake caused by chemotherapy.

In order to quantify effects of an experimental chemotherapy, MCF7 cells were studied with 14C-fluorodeoxyglucose (FDG) and high-performance liquid chromatography (HPLC). Uptake measurements were performed 1 and 4 hr after the end of a therapy with hexadecylphosphocholine (HPC). A dose- and time-dependent increase of the FDG uptake after therapy was observed, with a maximum at 1 hr after therapy. These data were used to develop a new metabolic design of combination treatment. Several time-dose combinations of HPC and deoxyglucose (DOG) were analyzed for their effects on growth inhibition. The combinations using DOG in the period of pronounced enhancement of FDG uptake (1 hr after HPC treatment) were found to be the most effective with an improvement of up to 520% in growth inhibition. This metabolic design of combination treatment may also be applied in vivo, and PET can be used to optimize the time and dose schedule of the modified treatment protocol.

Antineoplastic Agents↗
PubMed1992

[MR tomography of the bone marrow in malignant systemic diseases. Diagnosis and therapeutic follow-up control].

This paper presents a short survey of the current status of bone marrow diagnosis in systemic neoplastic disease by means of MR imaging. The different patterns of bone marrow infiltration from lymphomas and leukaemias are presented and the differential diagnoses are discussed. Apart from the primary diagnosis the relevance of conventional MRI and chemical shift imaging for therapy follow up and after-care is discussed.

Bone Marrow↗
PubMed1992

[Recurrence paralysis: computed tomographic analysis of intrathoracic findings].

The long and singular course of the inferior (recurrent) laryngeal nerve makes it very vulnerable to infiltration by tumors of various locations. In particular, mediastinal and pulmonary lesions must be considered in the case of left vocal chord palsy. Recurrent nerve paralysis caused by a tumor indicates advanced disease. We retrospectively reviewed the computed tomography (CT) findings in 29 patients with bronchogenic carcinoma or mediastinal tumors and recurrent nerve paralysis with respect to the site, size and extent of the tumor and the lymph node status. The review revealed a marked predominance of left upper lobe tumors with extensive lymph node metastases to the anterior mediastinum and the aortopulmonary window. The extent of mediastinal involvement exceeded the average involvement in a control group of 30 randomly selected patients with bronchogenic carcinoma at the time of presentation. In all patients CT demonstrated tumor tissue which could have caused the paralysis at one or more sites along the anatomical course of the recurrent nerve. In most cases the tumor was located at the aortic arch. The left paratracheal region, right paratracheal region and right pulmonary apex were affected in one case each. We conclude that in patients with cancer, CT is a suitable method for localizing a recurrent nerve lesion.

Carcinoma, Bronchogenic↗
PubMed1992

[Mesothelioma of the pleura--diagnosis with imaging procedures].

Typical radiological findings in patients with diffuse malignant pleural mesothelioma are nodular opacities of the pleura including the fissures, pleural effusion, shrinking of the ipsilateral hemithorax, and mediastinal shift. The radiological differentiation between pleural mesothelioma and benign pleural tumors is possible; however, a secondary metastatic pleural involvement imitates pleural mesothelioma. Magnetic resonance imaging is superior to computed tomography in the preoperative assessment of tumor extension, because it demonstrates exactly the tumor extension in the coronal or sagittal plane. The noninvasive ultrasound examination is helpful in the evaluation of the diaphragmatic pleura and the costodiaphragmatic spaces.

Diagnosis, Differential↗
PubMed1992

Therapy monitoring of presacral recurrences after high-dose irradiation: value of PET, CT, CEA and pain score.

21 patients were followed by positron-emission-tomography (PET) FDG (18Flourdeoxyglucose) uptake, physical examination, CT and CEA levels after combined photon-neutron irradiation for inoperable recurrent rectal carcinoma. In order to evaluate the response to radiotherapy symptomatic relief, CEA levels, decrease of tumor volume measured by CT analysis were correlated with the FDG-uptake. The objective of this study was also to investigate if the level of FDG-uptake prior to radiotherapy or the early decrease after therapy can be used as a prognostic factor. Prior to radiotherapy sacral pain was the predominant symptom. All malignancies showed measurable tumor masses, evaluation of CEA levels and enhanced tracer accumulation of FDG in the PET cross section. The mean FDG-uptake before radiotherapy was 2.3 +/- 1.1 (range 1.1 to 5.0) in 21 patients in contrast to 1.9 +/- 0.7 (range 0.8 bis 4.0) three months after radiotherapy. In six patients FDG concentration values decreased to the range of normal soft tissue, moreover, two of them relapsed after six and 22 months. Elevated FDG-uptake of the sacral bone was noted in PET cross sections in two patients, while there was no evidence of osseous alterations in CT. Normal levels of CEA were achieved in 14 patients and complete or partial pain relief in 20 of 21 patients. A decrease of tumor volume of more than 50% was detected in the follow-up CT scans of three patients but no complete remission was found. The result suggests that enhanced glucose uptake is associated with recurrent rectal cancer. However, enhanced glycolytic activity is related not only to malignant cells but also to all proliferating cells. To distinguish between proliferation, repair, inflammation, and residual viable tumor cells is not possible and may be responsible for an unchanged or elevated FDG-uptake after radiotherapy.

Adenocarcinoma↗
PubMed1992

[Measurement of the blood flow velocity in the pulmonary arteries using the magnetic resonance technique].

MR blood velocity measurements were performed by the RACE technique in a plane perpendicular to the flow of the pulmonary arteries. MR findings were correlated with those of perfusion scintigraphy, Doppler US and right heart catheter (thermodilution). The ratio of MR blood flow measurements of right and left pulmonary arteries correlated well with the results of perfusion scintigraphy (RPA to LPA) and Doppler. Poor correlation was found when comparing MR blood flow measurements with right heart catheter since absolute flow measurements can be superimposed by neighboring blood vessels in complex anatomic situations.

Adolescent↗
PubMed1992

[Positron emission tomography of the thorax. The current clinical status].

The non-invasive diagnostic assessment of thoracic lesions has been greatly enhanced by the use of positron emission tomography with metabolic active radio-compounds such as fluor-18 labeled deoxyglucose. Four clinical fields of use were established: differential diagnostic evaluation of lesions (T-staging); classification of adenopathy (N-staging); therapy response monitoring; diagnostic evaluation of recurrence. The upcoming challenges for clinical use are limited availability and necessary technical and qualitative standardizations.

Carcinoma, Bronchogenic↗
PubMed1992

[Positron emission tomography (PET) in the evaluation of tumor proliferation and follow-up of therapy in ear, nose and throat tumors].

The uptake of 18F-Deoxyglucose (FDG) was studied in vivo in patients with head and neck tumors with positron emission tomography (PET) in relation to the proliferation rate of these tumors. The quantitative analysis of the radioactivity concentrations revealed two groups, showing a high or a lower FDG uptake pattern. In both groups the FDG uptake and the proliferation rate were correlated with a flat slope of the regression function. It is suggested that these differences in uptake in histologically identical tumor populations may correspond to differences at the molecular level, e.g. differences in the amount of the glucose carrier, perhaps caused by activated oncogenes. Furthermore PET was applied to evaluate therapeutic effects in patients with advanced head and neck cancer. We found that multiple lymph node metastases in the same patient can show a different baseline metabolism and also different changes following therapy. Tumors were more sensitive to therapy than lymph node metastases. The growth rate and the change in FDG uptake were highly correlated with different regression functions for tumors and lymph node metastases. These data demonstrate that PET with FDG can be used to assess early chemotherapeutic effects. The information gained with PET can be included in the treatment planning in patients undergoing systemic chemotherapy.

Carcinoma, Squamous Cell↗
PubMed1991

Computerized ultrasound B-scan texture analysis of experimental diffuse parenchymal liver disease: correlation with histopathology and tissue composition.

By means of statistical pattern recognition procedures, a quantitative description of the ultrasound B-scan images of experimental diffuse liver disease has been carried out. Fatty livers, fatty fibrosis/cirrhosis, and cirrhosis without fatty infiltration of the liver were studied in female Wistar rats. Separation accuracies of more than 80% between the tissue classes "normal" vs "fatty infiltration," or "normal" vs "fatty cirrhosis," using only two statistical image parameters were found. A subclassification of the diffuse parenchymal liver disease was not possible. It is shown by multiple linear regression analysis that the image parameter "mean grey level" correlates better with total lipid content than with the amount of connective tissue. Furthermore it is demonstrated that connective tissue leads only to a weak increase in "mean grey level," whereas the addition of connective tissue to a given tissue lipid can lead to a reduction in image brightness.

Animals↗
PubMed1991

[MR tomography and MR angiography in cerebral arteriovenous malformations].

Av malformations are cerebral abnormalities with a high risk of bleeding. The role of MRI and MR angiography (MRA) for demonstrating these congenital vascular malformations has been studied. It has been shown that MRI/MRA can provide a rapid and certain diagnosis. MRA can demonstrate arteries to the second set of branches beyond the main cerebral vessels. It has the advantage of being able to produce rapidly and noninvasively 3-D images and, unlike conventional angiography, it can be repeated at will. The disadvantage is the limited special resolution and the difficulty in distinguishing between arteries and veins.

Adolescent↗
PubMed1991

[Computed tomography of the upper mediastinum. Optimized contrast media application by the use of an infusion pump].

The aim of this study is to show the advantages of a power injector for contrast media application in comparison to manual bolus injection. The evaluation of 144 studies showed significant improvements for the examinations using the power injector based on densitometry in selected vessels (average enhancement 348 vs 280%) as well as subjective evaluation of contrast quality (3.4 pts vs 2.3 pts on a subjective scale) and contrast-induced artifacts (1.8 vs 2.3 on a subjective intensity scale). All parameters show that an increased, more reliable, and homogeneous enhancement can be obtained by application of the power injector compared to manual bolus injection technique using the same amount of contrast media (100 cc). Due to the possible standardisation of this technique, the results are reproducible. Increased reliability in expected diagnostic gain can be obtained using our technique for intravenous contrast application. This introduced technique requires no additional monetary or time expense and is therefore applicable for clinical routine work.

Contrast Media↗
PubMed1991

[Influence of abdominal wall composition and thickness on ultrasound B scan].

Using a tissue-mimicking phantom and a computerised sonography system an ultrasound b scan analysis was performed. The images were acquired with different fat-muscle combinations as ultrasound wave path. These are simulations of a different composition or thickness of the abdominal wall. The analysis of the ultrasound images was performed using mathematical statistical parameters for ultrasound tissue characterisation. We examined the influence of the thickness or composition of the abdominal wall on ultrasound image brightness, microtexture and macrotexture. A dependence of ultrasound image brightness and microtexture on the thickness of the fat path was observed. Muscle tissue shows only a weak influence on the microtexture of the ultrasound image. These data demonstrate that a thick fat layer leads to a darker and diffuse image. This disturbs the evaluation e.g. of the liver parenchyma by analysis of the echo structure and may lead to false diagnoses especially in adiposity.

Abdominal Muscles↗