Biomedical subjects

R Felix

Publications and source records attributed to R Felix.

At least 19 recordsLinked to original sources

PubMed1992

Detection of transcripts for the receptor for macrophage colony-stimulating factor, c-fms, in murine osteoclasts.

Macrophage colony-stimulating factor (M-CSF), whose action is restricted to the cell populations of the mononuclear phagocyte system, has recently been found to be required for osteoclastogenesis and bone resorption. To investigate the cells involved in the action of M-CSF in these processes, expression of c-fms mRNA, encoding the M-CSF receptor, was studied by in situ hybridization. Paws from murine embryos and newborn mice, tibiae from 2-day-old animals, as well as isolated osteoclasts, were hybridized with a c-fms-specific RNA probe. In bone, c-fms mRNA was detected only in cells at the late stages of osteoclastogenesis and in mature osteoclasts. The findings strengthen the relation between osteoclasts and the mononuclear phagocyte system. Furthermore, they suggest that M-CSF acts directly on osteoclast precursors and on mature osteoclasts during osteoclastogenesis.

Animals↗

PubMed1992

[Radioimmunoscintigraphy of colorectal tumors with 99m-Tc marked CEA antibodies. Indications and clinical value].

In Germany, radioimmunoscintigraphy (RIS) (scintigraphic, specific imaging of benign and malignant diseases by radioactively labelled monoclonal antibodies) has been employed since 1985 in clinical trials involving patients with colorectal cancer. After proving successful for identifying primary tumors, RIS is now increasingly being used for the early diagnosis of recurrent and metastatic lesions. In this prospective study involving 75 patients with colorectal tumors confirmed by endoscopy and biopsy, it was shown that RIS using the SPECT technique with 99m-Tc-labelled monoclonal CEA antibodies has a sensitivity of 78% in the detection of local recurrent disease in cases in which diagnostic work-up has been inconclusive.

Adult↗

PubMed1992

Transcranial Doppler ultrasound in internal carotid artery and middle cerebral artery disease.

Using noninvasive transcranial Doppler sonography, we studied cerebral collateral patterns in 30 patients with stenosis and/or occlusion of the extracranial internal carotid artery (ICA). All patients with unilateral ICA stenosis less than or equal to 80% had normal transcranial Doppler findings. 80% of patients with unilateral and 50% of patients with bilateral ICA stenosis of more than 80% including those with occlusion showed a collateralization via the ipsilateral anterior and/or posterior cerebral artery. 20% of patients with unilateral and 50% of patients with bilateral ICA stenoses of more than 80% (including occlusion) had two or three collateral pathways, including the ophthalmic artery. Another ten patients with stenosis or spasm of the middle cerebral artery (MCA) showed increased flow velocities with turbulence in the narrow segment. In four patients with severe MCA disease with a systolic peak velocity of more than 200 cm/s, the Doppler waveform distal to the lesion was damped. Decreased regional cerebral blood flow (rCBF) measured by 99mTc-HMPAO-SPECT was found in two patients with severe MCA stenosis. Another patient with moderate MCA stenosis with a systolic peak velocity of 140 cm/s showed a normal cerebral perfusion pattern.

Adolescent↗

PubMed1992

[Catheter-induced femoral artery lesions: diagnosis with B-mode ultrasound, Doppler ultrasound and color Doppler ultrasound].

A total of 44 patients were evaluated to compare the value of B-mode sonography, Doppler sonography and colour coded Doppler sonography. All patients were studied because of suspected lesions of the femoral arteries following diagnostic and/or therapeutic cardiac catheterisation. B-mode sonography was unable to reliably differentiate between haematoma and pseudo-aneurysms, a.v.-fistula or combined lesions. Colour coded Doppler sonography can better demonstrate haematoma and thrombi in pseudo-aneurysms. The neck of a pseudoaneurysm can be exactly depicted by colour coded Doppler sonography. A.v.-fistula is shown by colour coded Doppler sonography based on typical colour coding and the Doppler spectrum. Combined lesions of pseudo-aneurysm and a.v.-fistula cannot reliably be detected by colour coded Doppler sonography, duplex sonography and B-mode sonography.

Adult↗

PubMed1992

The significance of diagnostic imaging in acute and chronic brain damage in boxing. A prospective study in amateur boxing using magnetic resonance imaging (MRI).

The significance and possible extent of structural damage to the central nervous system (CNS) due to boxing are investigated. Bleeding, especially microhematomas, is considered to be one probable cause of the chronic encephalopathy in boxers. In a prospective study, 13 amateur boxers were investigated with the help of MRI several times before and after their fights. The MRI investigations were accompanied by neurologic examinations before and after the fights. Among the 13 boxes, 5 demonstrated focal neurological signs following the fights, without evidence of small hematoma or other structural alterations. The number of head punches did not correlate with the occurrence of neurologic signs. These results indicate that up to now imaging methods cannot clarify the development of chronic encephalopathy.

Acute Disease↗

PubMed1992

[The value of radioimmunoscintigraphy compared to computed tomography in the diagnosis and relapse diagnosis of colorectal tumors].

Radioimmunoscintigraphy (= RIS, scintigraphic "specific" imaging of benign and malignant diseases by means of radioactively marked monoclonal antibodies) has been performed in Germany in clinical studies since 1985 in patients suffering from colorectal cancer. After having been successfully proven in primary studies, RIS is now being used in the early diagnosis of recurrences and metastases. In the prospective study presented here the clinical usefulness of RIS was assessed in comparison against well-tried diagnostic methods including computed tomography in patients suffering from colorectal cancer. It was shown that RIS in SPECT technique (= single photon emission computed tomography) with 99mTc-labelled monoclonal CEA antibodies can visualise local recurrences if diagnostic findings are doubtful, with a sensitivity of 78% versus 50% for CT findings.

Adult↗

PubMed1992

[Oral contrast media for the magnetic resonance tomography of the abdomen. A clinical trial of the tolerance for gadolinium-DTPA].

Safety and efficacy of gadopentetate-dimeglumine (Gd-DTPA) as a MR bowel contrast agent were determined in 133 patients with CT-proved abdominal and retroperitoneal mass lesions using a buffered formulation (1 mmol/l Gd-DTPA, 15 g/l mannitol, 25 mmol/l sodium-citrate, 6-17 ml/kg). Short-lived gastrointestinal side effects were noted in 32% of patients. Gd-DTPA provided uniform, hyperintense bowel labelling and contrast enhancement in the region of interest in 81% of patients. Among 78 patients with pre- and postcontrast images lesion delineation was improved in 62%. In 55 studies with postcontrast images only, Gd-DTPA proved useful in 65%. In 105 of 109 cases IV injection of scopolamine or glucagon eliminated image artifacts arising from peristalsis of opacified bowel. The authors conclude that Gd-DTPA is a safe and effective MR bowel contrast agent.

Abdomen↗

PubMed1992

[The HR computed tomography of interstitial lung diseases].

In 50 patients with pulmonary disease of varying aetiology and involvement of the pulmonary interstitium, high resolution CT with 1 mm sections have been performed. Various morphological changes within the secondary lobule could be demonstrated which helped in reducing the differential diagnosis. Compared with conventional CT with 10 mm cuts it was also possible to improve the demonstration of pleural lesions by changing window levels.

Asbestosis↗

PubMed1992

[Cervical lymph node metastases. The sonographic demonstration of malignancy].

The value of sonography for demonstrating cervical lymph node metastases has been studied, using longitudinal and transverse measurements as criteria for malignancy. A transverse/longitudinal quotient greater than 2 indicates the presence of metastases with a 96% assurance. Using only longitudinal measurements lymph node metastases can be excluded with only a 36% assurance. The sensitivity of both methods also differs (95% for the maximal transverse quotient as against 90% for longitudinal measurements). The use of the maximal transverse quotient increases specificity from 36 to 96%. This gives sonography an accuracy of 95%.

False Negative Reactions↗

PubMed1992

["Surgical projection" in the gadolinium-DTPA (Gd-DTPA)-supported NMR tomographic diagnosis of lateral lumbar disk prolapse].

In a group of 25 patients the coronal views of plain and Gd-DTPA-enhanced MRI studies were correlated with CT and operative findings. All series included sagittal, transverse and coronal FLASH sequences (GE 500/6, flip angle 70 degrees), sagittal proton density-(SE 2500/15) and T2-(SE 2500/70) weighted images. MR diagnosis proved to be correct in all cases. Compared to CT and axial MRI herniated disk material in the lateral intravertebral space and its relationship to nerve roots was demonstrated more clearly on coronal views.

Adult↗

PubMed1992

[The regional cerebral circulation in infarct patients. Rapid dynamic T2*-weighted MRT after a bolus injection of gadolinium-DTPA].

The aim was to validate the MRI assessment of regional cerebral blood flow. Measurements were performed on a 1.5 T imaging system using a fast T2*-weighted gradient-echo sequence. After intravenous injection of gadolinium-DTPA 30 images were acquired in the same slice position during 84 seconds. In 12 volunteers we observed a symmetrical cortical decrease of signal intensity during the passage of the contrast medium. In 9/23 patients with impairment of cerebral blood flow a circumscribed area of reduced signal intensity decrease (hypoperfusion) was found. In 4/23 patients the decrease of signal intensity was more pronounced than in normals (hyperfusion). In 9/23 patients signal intensity changes were normal. HMPAO-SPECT confirmed successful MRI assessment of cerebral blood flow in 22/23 patients.

Cerebral Infarction↗

PubMed1992

[Magnetic resonance tomographic screening studies of the bone marrow with gradient-echo sequences. II. Gadolinium-DTPA-supported studies of plasmocytoma patients].

MR imaging was performed in 19 patients with proven multiple myeloma. Both plain and Gd-DTPA enhanced in-phase and opposed-phase gradient-echo techniques were used (0.1 mmol Magnevist/kg body weight). Plain, opposed-phase imaging demonstrated more lesions than plain in-phase imaging (35 vs. 16); enhanced opposed-phase imaging demonstrated more lesions than plain opposed-phase and enhanced in-phase imaging (47 vs. 35 and 17 lesions). These results suggest that enhanced opposed-phase images which have a high contrast between normal and infiltrated bone marrow are especially suited for MR screening in multiple myeloma.

Bone Marrow↗

PubMed1992

[Computed tomography: the TNM staging of laryngeal carcinoma].

In 64 patients with malignant lesions of the larynx, CT and microlaryngoscopy (ML) were evaluated in terms of T-staging. Histological information was present in all cases following operation. CT showed an accuracy of 90% in T-staging. ML showed an accuracy of only 71% of correct T-staging. CT is superior to ML particularly in distinguishing between stages T3 and T4 and T1 and T2. CT tends to overestimate tumour stage whereas ML tends to underestimate it. CT was also compared with palpation and sonography as regards N-staging. In this respect sonography has the highest accuracy (94%) followed by palpation (76%) and CT (74%).

Carcinoma↗

PubMed1992

[Magnetic resonance tomography (MRT) in pleural diseases. A comparison with CT and histopathological findings].

The MRI and CT appearances in 48 patients with histologically confirmed benign and malignant pleural abnormalities were compared retrospectively. Abnormal pleural changes were shown in 47 out of the 48 patients by high signal intensity of the pleura in T2-weighted sequences and in contrast enhanced T1-weighted sequences on MRI. CT showed abnormalities in 45 out of 48 patients. Delineation of pleural and pulmonary changes by CT was possible in 13 out of 23 cases, and pleural disease from effusions in 15 out of 28 cases. T2-weighted MRI was successful in 14 out of 23 and 4 out of 28 cases, respectively. T1-weighted images after contrast were successful in 20 out of 23 and 22 out of 28 cases, respectively. Indications of malignant pleural disease were the presence of mediastinal or circumferential involvement or involvement of the entire pleura, thickness of more than 10 mm and nodular changes. The most reliable sign of malignancy was infiltration of the thoracic wall and the diaphragm; this was better demonstrated by MRI (18 out of 19 and 2 out of 2 cases) than by CT (14 out of 19 and 0 out of 2 cases).

Adult↗

PubMed1992

[The regional blood flow in intracranial tumors: a comparison of HMPAO-SPECT with a newer magnetic resonance tomographic procedure].

We compared the value of gadolinium-enhanced first-pass MRI perfusion studies and HMPAO-SPECT for the assessment of regional cerebral blood flow in a prospective study of 23 intracranial tumour patients. In five tumours with homogeneous hypoperfusion and eight tumours with homogeneous hyperperfusion, tumour blood flow patterns in MRI and HMPAO-SPECT were similar. By contrast, in ten patients with inhomogeneous tumour blood flow pattern only MRI was able to differentiate between tumour areas with no or low flow, tumour tissue with high flow, and perifocal oedema with reduced flow. In HMPAO-SPECT, these inhomogeneous tumours were represented as areas of homogeneously reduced tracer retention corresponding to different tumour constituents and perifocal oedema. In conclusion, the high spatial resolution of MRI enables a detailed analysis of tumour blood flow.

Brain↗

PubMed1992

[The determination of cerebral dopamine (D2) receptor density by using 123I-IBZM-SPECT in Parkinson disease patients].

An alteration of the dopaminergic nigrostriatal system is believed to be the main pathogenetic factor of Parkinson's disease (PD). We report on our initial results on the determination of the post-synaptic dopamine-D2-receptor binding of 123I-IBZM in patients with PD. Drug-native patients showed a significantly higher IBZM binding in the basal ganglia as compared to patients on specific dopaminergic medication. Age, duration of the disease and the severity of the disease do not seem to influence the IBZM-receptor binding. We conclude that 123I-IBZM-SPECT is an extremely useful tool for the evaluation of the functional state of cerebral dopamine-D2-receptors.

Aged↗

PubMed1992

[The magnetic resonance tomographic differential diagnosis between reactively enlarged lymph nodes and cervical lymph node metastases].

A prospective study was carried out involving 27 patients to determine whether MRT can distinguish between lymph node metastases and reactive lymph node enlargement. The results of MRT were compared with the pathological findings. Using T1 and T2 weighted sequences and proton density sequences it was not possible to differentiate between reactively enlarged lymph nodes and lymph node metastases. Following the administration of Gd-DTPA the observation of central hypo-intensity with marginal hyper-intensity is a reliable sign of a lymph node metastasis. Using the criterion of length greater than 10 mm for lymph node metastases results in a specificity of 32% and sensitivity of 75%. The use of the sonographic maximal/cross measurement quotient > 2 in the axial/coronary/sagittal dimension improves specificity and sensitivity to 94%.

Contrast Media↗

PubMed1992

[Magnetic resonance tomography in the follow-up after the embolization of arteriovenous malformations of the central nervous system].

Interventional embolisation is an accepted treatment for intracranial or spinal arteriovenous malformations. Since multiple embolizations are often required, noninvasive repeatable follow-up studies are desirable. The aim of this study is to demonstrate the usefulness of T2-weighted images, MR angiography, and gadolinium-DTPA first-pass studies for post-embolisation follow-up studies. Five patients with arteriovenous malformations, four cerebral and one spinal, were studied prospectively before and repeatedly after single or multiple embolizations. A total of 26 MRI studies (1.5 T Magnetom, Siemens AG) were performed. The combination of T2-weighted images, MR angiography, and gadolinium-DTPA first-pass studies nicely demonstrated the arteriovenous malformations and the effect of embolisation which ranged from negligible to almost complete. While contrast-enhanced T1-weighted images and contrast-enhanced MR-angiography seemed to be of little more value than unenhanced studies, gadolinium-DTPA first-pass studies appeared to be more sensitive than T2-weighted images or MR-angiography because of their high intrinsic sensitivity to regional blood flow and volume. In the spine, T2-weighted images and MR-angiography were too insensitive to detect arteriovenous malformations, whereas gadolinium-DTPA first-pass studies sensitively detected the malformation and the changes after embolizations.

Adult↗