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Biomedical subjects

R Felix

Publications and source records attributed to R Felix.

At least 613 records · Page 34Linked to original sources
PubMed1990

[The Berlin Radiology Communication Project. The initial clinical experiences].

As part of a radiological communication project (RADKOM), two PACS systems of the radiological clinic in the Rudolf Virchow University Clinic in Charlottenburg and Wedding were connected via the BERKOM network of the German post office. Within the radiology departments, all CT and MRT systems were joined through a local network. The first results have shown that the PACS stations are of value for providing uniformity of diagnosis and for radiological conferences. It is evident, however, that the speed of transfer and the architecture within the PACS system would be of crucial importance for their practicability for radiological conferences.

Berlin↗
PubMed1990

MR-imaging findings in children with Sturge-Weber syndrome.

Intracranial extent and distribution of leptomeningeal angiomatosis, visualized by magnetic resonance imaging (MRI) with Gadolinium-DTPA (Gd-DTPA) enhancement, is demonstrated in four children with Sturge-Weber syndrome (SWS). Aged 7, 9, 11 and 19 months, they presented with cutaneous, neurologic and ocular symptoms at the time of MRI examination. Angiomatous alteration of the skull, atypically located and congested intracerebral and basal veins as well as intracerebral changes secondary to the leptomeningeal angiomatosis are demonstrated with T2 weighted images. Gd-DTPA enhanced T1 weighted images exhibit clearly the regional distribution of angiomatosis in the skull, meninges and within the brain. Before calcifications in children with SWS are detectable by CT, MRI is the method of choice to detect intracranial involvement. Enhancement with Gd-DTPA improves the diagnostic value of MRI, before neurological symptoms appear. Follow-up studies with Gd-DTPA enhanced MRI can be applied to recognize thrombotic changes of leptomeningeal angiomatosis as well as subsequent intracerebral impairment.

Atrophy↗
PubMed1990

Macrophage colony stimulating factor restores in vivo bone resorption in the op/op osteopetrotic mouse.

The op/op variant of murine osteopetrosis is a recessive mutation characterized by impaired bone resorption due to lack of osteoclasts. Cultured osteoblasts and fibroblasts from this mutant do not secrete M-CSF activity and resident macrophages are absent in bone marrow. This failure has been related to a mutation within the M-CSF coding region. We report now that the administration of recombinant human M-CSF (rhM-CSF) corrects in vivo the impaired bone resorption in this animal. The treatment restores the bone marrow cavity virtually absent in the op/op animal and induces the appearance of resorbing osteoclasts and of resident bone marrow macrophages. This proves that the deficiency of M-CSF is the cause of the op/op bone disorder and that this cytokine is directly or indirectly necessary for physiological osteoclastogenesis, the resulting bone resorption and for the establishment of bone marrow hemopoiesis.

Animals↗
PubMed1990

[Imaging procedures in abdominal tumors].

The value of imaging modalities in abdominal malignancies is discussed. Ultrasound is the first method to perform in hepatic tumors--HCC and liver metastases--, followed by CT and/or MRI. CT and ERCP are the diagnostic procedures of choice in pancreatic cancer. MRI is inferior to bolus-enhanced CT. CT and MRI are still equal in colorectal cancers for differentiating between scar and local recurrence after abdominal-perineal amputation.

Abdominal Neoplasms↗
PubMed1990

[Evaluation of recent vascular prostheses in the arteriovenous shunt].

Prosthetic vascular replacement materials are still suboptimal especially for distal peripheral and coronary bypass grafts due to the small caliber and high occlusion rates. Therefore new vascular grafts have been assessed with respect to blood compatibility, thrombogenicity and host pretreatment. In 12 heparinized minipigs (25 kg), a total of 120 small caliber grafts (i.d. 3.0 mm) were perfused (6 min) in a femoro-femoral arteriovenous shunt (AVS). Materials included: Dacron (Atrium), PTFE (Gore), Polyurethanes (PU), Auto- and Xenografts. Animals were treated preoperatively with fishoil (3 g EPA/QD x 3 weeks = group I), perioperatively with prostaglandins (PGE1 = group II) or with fishoil and graft incubation in plasma proteins (= group III) and compared to controls without pretreatment (= group 0). We measured flow, deposition of marked thrombocytes (HMPAO-Tc* per area and per weight). - Blood flow was similar in AVS for all groups and materials (168 +/- 86 ml/min, p = NS). There was no significant correlation in deposition of marked thrombocytes and host pretreatments (group 0: controls = 7356 counts/area, group I: fishoil = 6807. group II: PGE1 = 7864). However graft incubation in plasma proteins significantly lowered deposition of marked thrombocytes (1766 in group III vs. 7356 in group 0: p less than 0.05). And significant differences of thrombocyte counts where found between the different materials: Autografts less than PTFE less than Xenografts less than Small Pore PU less than Dacron less than Large Pore PU.--AVS is a useful tool to determine early thrombogenicity in prosthetic vascular replacement materials and to assess the effect of different host pretreatments.

Animals↗
PubMed1990

[A comparison of different methods of calculating clearances using 99mTc-mercaptoacetyltriglycine and 123I- or 131I-ortho-iodohippuric acid].

Using labelled MAG3 (n = 172) or OIH (n = 102) the results of three different techniques of calculating renal clearance were compared. The following techniques were used: Tauxe (single plasma concentration determination), Oberhausen (modified, combined partial body and plasma disappearance clearance) and Winkler (partial body clearance). For OIH, linear regression analysis revealed a positive correlation of Tauxe and Oberhausen clearances with a correlation coefficient (r) of 0.90 and a mean ratio (mean) Oberhausen/Tauxe clearances of 1.03. For MAG3, the Oberhausen values were found to be significantly lower than the Tauxe values with an equally good correlation. For this radiopharmaceutical the Winkler values were significantly higher than the Tauxe and Oberhausen values. For OIH, no such difference was noted. However, the correlation coefficient was significantly lower. Whereas with the Tauxe method, a mean ratio MAG3-/OIH clearances of 0.62 was observed in an earlier investigation, from the present data a ratio of 0.53 is calculated for the Oberhausen clearance. The difference between the Tauxe and Oberhausen clearances with MAG3 is of importance when comparing clearance values obtained with clearance calculation techniques and for establishing normal values for the MAG3 clearance.

Adult↗
PubMed1990

[Angiographic diagnosis in liver transplantation. I: Evaluation before transplantation].

Our study covers angiographic pretransplant evaluation from 9/88-4/90. 57 out of 73 patients (78%) underwent pretransplant angiography. In all cases aortography, angiographies of the coeliac axis, the superior mesenteric artery, the splenic artery, and portograms were obtained. The arterial studies evaluated the arterial blood supply of the liver, the diameter of the common hepatic artery, aneurysms and a steal effect of the splenic artery. Portography revealed the exact venous collateralisation. Thus angiography remains a valuable procedure for pretransplant evaluation besides ultrasongraphy.

Aneurysm↗
PubMed1990

[Cavernous hemangioma of the maxillary sinus].

Cavernous haemangioma of the paranasal sinuses is very rare. We describe the X-ray and CT findings in a case of cavernous haemangioma which originated from the mucous membrane of the maxillary sinus and eroded the bony boundary of the sinus.

Diagnosis, Differential↗
PubMed1990

[The influencing factors and interfering effects in the control of the power distributions with the BSD-20000 hyperthermia ring system. 1. The clinical observables and phantom measurements].

A new generation of annular-phased-array systems BSD-2000 has been clinically applied in a pilot study. Therapeutic intratumoral temperatures greater than 42 degrees C were obtained in 15/15 sessions with six patients. However, the control of power deposition pattern has to be improved in order to increase the therapeutic gain and to guarantee an efficient therapy. A retrospective analysis of clinical phenomena has been performed by phantom set-ups because the power deposition pattern cannot be determined during therapy. Phantom measurement techniques are outlined, specifically phantom materials and visualization of power distributions. The problem of focus balance and frequency choice is illustrated by self-developed phantoms (liquid crystal sheets, light-emitting-diode-arrays). Especially, the limitation of modeling calculations is demonstrated.

Evaluation Studies as Topic↗
PubMed1990

[MRI of an intrathoracic malignant tumor invading the chest wall].

22 patients with intrathoracic malignant tumors suspected of invading the chest wall were examined with CT and MRI. Chest wall invasion was operatively confirmed in 19 cases and excluded in the other 3 cases. CT showed tumor infiltration of the chest wall in 14/19 cases, no morphological changes in 5/19 cases. Thoracic wall invasion was demonstrated by MR in all 19 cases. Typical MR finding of malignant invasion was local lesion within the chest wall showing high signal intensity in post-Gd T1-weighted images and in T2-weighted images. Reactive inflammatory changes as well as malignant infiltration of the pleura showed high signal intensity on enhanced T1-weighted images and on T2-weighted images.

Adult↗
PubMed1990

[Value of magnetic resonance tomography in Pancoast and other tumors with infiltration of the thoracic wall].

Twenty-two patients with intrathoracic malignancies and suspected Pancoast and "break-out" tumours were submitted to a comparative investigation using CT scanning and MRI to detect infiltration of the chest-wall. In the patients, the lesion had been confirmed at surgery, which revealed malignant infiltration in 19 cases, and excluded in filtration in 3 cases. In 14 out of 19 patients, the CT scan revealed tumourous involvement of the chest-wall, while in five out of 19 patients, no such involvement was detected. Using MR imaging, tumour infiltration was detected in all 19 patients. A reliable MR sign of tumour involvement was the detection of signal-intensive lesions within the chest-wall in T1-weighted images following the administration of Gd-DTPA, and in the T2-weighted images. In contrast, signal enhancement of the pleura was found both in tumour involvement and in inflammation. In suspected tumorous chest-wall invasion MR imaging can demonstrate tumour involvement of the chest-wall when CT is equivocal.

Adult↗
PubMed1990

[Vascular pedicled pelvic bone span. Value of digital subtraction angiography in pre- and postoperative diagnosis].

The pedicled pelvic bone graft is a new operative technique for the treatment femoral head necrosis. 29 femoral head necroses were examined by i.a. DSA before a pedicled pelvic bone graft was implanted. 11 pedicled pelvic bone grafts were investigated postoperatively. The pre- and postoperative findings are presented. I. a. DSA is a valuable method for the evaluation of the vascularisation of the femoral head before and after surgery.

Adult↗