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Biomedical subjects

R Felix

Publications and source records attributed to R Felix.

At least 451 records · Page 25Linked to original sources
PubMed1994

Recurrent cervical lymphadenopathy: differential diagnosis with color-duplex sonography.

In this prospective study 45 patients with cervical lymphadenopathy treated by operation, radiation and/or chemotherapy were examined by color-duplex sonography. The aim was to investigate the lymph node perfusion and to find out whether differentiation between benign and malignant nodal disease after therapy was possible by resistance and pulsatility indices. In 200 of 245 lymph nodes (82%) color-duplex sonography was able to detect perfusion. Using a pulsatility index (PI) threshold of 1.6 and resistance index (RI) threshold of 0.8, differentiation between reactive nodal enlargement and metastases was possible with an accuracy of 96%. Differentiation between lymphomas and metastases by RI and PI was not possible. Qualitative assessment of perfusional patterns was useful in detecting malignancy because reactively enlarged nodes showed greater hilar perfusion whereas metastases showed an increased peripheral perfusion. Lymphomas had both increased central and peripheral perfusions.

Adipose Tissue↗
PubMed1994

CT angiography of the pelvic arteries.

UNLABELLED: A comparison was performed between CT angiography and digital subtraction angiography (DSA) on 55 patients with atherosclerotic obstructions of the pelvic arteries. Two post-processing algorithms were employed, maximum intensity projection (MIP) and 3D technique. RESULTS: (a) MIP: conformity with DSA: 20/23 occlusions and 24/36 stenoses; underestimation: three occlusions, seven stenoses; overestimation: five stenoses. (b) 3D display: conformity with DSA: 19/23 occlusions and 16/36 stenoses; underestimation: four occlusions, 17 stenoses; overestimation: three stenoses. The MIP technique proved to be the only method to display the localisation of vascular calcifications with their exact topographical relationship to the stenoses and occlusions. MIP also proved to be valuable in controlling the position of intravascular stents. Complementary to DSA, the MIP method therefore seems to be a clinically valuable technique for calcified and non-calcified stenoses, and for displaying intravascular stents. Its use in interventional procedures could therefore become increasingly important.

Adult↗
PubMed1994

Radioimmunoscintigraphy of squamous cell carcinoma in the head and neck region.

Radioimmunoscintigraphy (RIS) with a monoclonal antibody (SQ 174, Biomira, Inc, Canada) is introduced as a new diagnostic method for detection of squamous cell carcinoma in the head and neck region. RIS could detect eight of the 10 primary tumors. One patient had histopathologically proven nodal disease. This lymph node was seen in RIS. No false positive results were seen in RIS, whereas sonography, computed tomography, and magnetic resonance imaging showed several false positive results.

Aged↗
PubMed1994

Value of magnetic resonance imaging in staging carcinomas of the oral cavity and oropharynx.

The value of magnetic resonance imaging (MRI) in preoperative tumor (T) staging was assessed prospectively in 46 patients with malignant carcinomas of the oropharynx and oral cavity. In each case, the MRI findings were compared with the preoperative clinical and postoperative histopathologic findings. MRI showed an accuracy of 89% in identifying the T stage, as compared with the histopathologic result. The accuracy of the clinical examination was 78%. Compared with the clinical examination, MRI is particularly suited for differentiating T3/T4 and the larger T2 tumors. MRI tends to overinterpret the T stage when the neighboring tissues are inflamed or edematous, as it allows no demarcation between inflamed or edematous tissue and tumor. Moreover, normal oropharyngeal mucous membrane and intrinsic tongue muscle both absorb contrast medium. In the clinical examination, the T stage is often underestimated, as the depth of infiltration and bone involvement cannot always be determined with certainty. The ability of MRI to give an axial, coronal, and sagittal image allows an exact preoperative view of tumor spread and assessment of infiltration into adjacent structures.

Adult↗
PubMed1994

[Sonography in tumor after-care of head-neck tumor patients. Value of sonomorphologic criteria and sonographic M/Q quotients].

The ranking of postoperative sonography is examined in respect of imaging of neck lymph node enlargement and neck lymph node metastases or lymphomas, using a prospective study involving 119 patients whose head and neck tumours had already undergone treatment. These patients had been subjected to tumour aftercare for an average period of 26 months. The resulting quotient values (M/Q-Quotient) and the transverse and long axis lengths, respectively, were used as diagnostic criteria for suspicion of malignancy. A cervical lymph node with an M/Q-Quotient greater than two ruled out a metastasis with 94% accuracy. A quotient of less than two confirmed the presence of a metastasis with 92% accuracy. In comparison, evaluation using the transverse axis method ruled out metastasis in 92% of the cases, with a sensitivity of only 83%. The presence of sonomorphological criteria as a highly medullary reflex at the centre of the lymph node or excentric widening of cortex improves diagnostic safety.

Adult↗
PubMed1994

[[111In]-DTPA-D-phenylalanine octreotide SPECT for the scintigraphic imaging of enhanced somatostatin-receptor density in endocrine ophthalmopathy].

Recently, [111In]-DTPA-D-phenylalanine-octreotide was introduced for clinical use. This radioligand binds specifically to somatostatin receptors and is suitable for SPECT examinations. The aim of this study was to clarify whether an increased somatostatin receptor density can be imaged and quantified in patients with endocrine ophthalmopathy (e.o.). 7 patients between 34 and 55 years with e.o. at stages III to VI and 4 controls between 38 and 63 years were examined. All patients and controls received approximately 200 MBq [111In]-DTPA-D-phenylalanine-octreotide by IV injection. A SPECT examination was performed 4 hours after injection and a normalised tracer uptake (A(n)) was calculated for both orbitae. In patients with e.o. the values of A(n) were significantly higher compared with controls (P = 0.002). There was a correlation between A(n) and exophthalmus stages according to Hertel with r = 0.844 (P = 0.001). These results indicate that [111In]-DTPA-D-phenylalanine-octreotide SPECT might be useful for the in vivo assessment of an increased somatostatin receptor density in e.o. These findings could have an impact on the treatment with somatostatin analogous in e.o.

Adult↗
PubMed1994

[MRT of the liver in Wilson's disease].

To show that Wilson's disease is one likely cause of multiple low-intensity nodules of the liver we obtained MR images in 16 patients with clinically and histopathologically confirmed Wilson's disease. Corresponding to morphological changes MRI enabled the subdivision of the patients into two groups. Using a T2-weighted spin-echo sequence (TR/TE = 2000/45-90) liver parenchyma showed multiple tiny low-intensity-nodules surrounded by high-intensity septa in 10 out of 16 patients. 5 patients had also low-intensity nodules in T1-weighted images (TR/TE = 600/20). In patients of this group histopathology revealed liver cirrhosis (n = 7) and fibrosis (n = 2). Common feature of this patient group was marked inflammatory cell infiltration into fibrous septa, increase of copper concentration in liver parenchyma and distinct pathological changes of laboratory data. In the remaining 6 patients no pathological change of liver morphology was demonstrated by MRI corresponding to slight histopathological changes of parenchyma and normal laboratory data. As low-intensity nodules surrounded by high intensity septa can be demonstrated in patients with marked inflammatory infiltration of liver parenchyma MRI may help to define Wilson patients with poorer prognosis. In patients with low-intensity nodules of the liver and unknown cause of liver cirrhosis laboratory data and histopathology should be checked when searching for disorders of copper metabolism.

Adolescent↗
PubMed1994

[Cerebral aneurysms: their 3-dimensional imaging with spiral CT].

In this study, the possibility of non-invasive, three-dimensional demonstration of aneurysms of the basal cerebral arteries by means of spiral CT was investigated. The first step was to obtain exact definition of optimal examination parameters. Angio CTs at appropriate levels were performed on 10 subjects and time/density curves of the arterial and venous phases obtained in order to optimise the beginning of the arterial spiral CT series. The second step in this investigation was to examine 7 patients; in 6 of these basal aneurysms had been demonstrated by DSA. By means of multiplanar three-dimensional reconstruction from the data of the spiral CT it was possible to demonstrate 7 aneurysms with a diameter between 5 and 18 mm. Their position and relationship to the bony skull was also shown.

Adult↗
PubMed1994

[The value of the liver-specific superparamagnetic contrast medium AMI-25 for the detection and differential diagnosis of primary liver tumors versus metastases].

The value of the superparamagnetic contrast medium AMI-25 and its clinical acceptability was investigated in a phase-III-multicenter study. 18 patients with primary and secondary hepatic tumours were studied using T2- and T1-weighted spin-echo sequences, FATSAT sequences and FLASH-2-D-breathold sequences, both before and after intravenous application of AMI-25 (0.2 mmol GE/ml 15 mmol/kg KG in 100 ml 5% glucose infusion), using a 1.5 Tesla MRT (Magnetom 63 SP, Siemens). In 6 patients the MRT findings could be correlated with in vitro results within 30 minutes following surgical resection. In 8 patients a diagnosis of metastases was made. Amongst patients with primary liver tumours (FNH 6 cases, HCC 3 cases, adenomatosis 1 case) 3 of the 10 patients showed more lesions following the injection of contrast; similarly, in 4 patients of the 8 with secondary tumours contrast increased the number of visible lesions. The absence of contrast enhancement separated primary from secondary lesions. Amongst the patients with secondary liver tumours, in vitro correlation always showed more tumours than had been visualised whereas there was exact in vivo/in vitro correlation amongst patients with primary liver tumours.

Contrast Media↗
PubMed1994

[Indications for the application of a high resolution coil in MR tomography].

This is the first study with high spatial resolution Magnetic Resonance Imaging (MRI), performed with a high resolution coil in a clinical whole-body system. Measurements were recorded with a slice thickness of 2 mm. A 256 x 256 matrix and a 2.5 cm field of view were used resulting in a pixel size of 0.01 mm2. MR images of the skin, hand, wrist, knee and ankle of 14 healthy volunteers, of three anatomic pathology tissue specimens and of three formalin-fixed specimens were obtained. Normal anatomy was identified and compared with the three gross anatomic pathology sections. The skin, hands, wrists and ankles of 30 patients were examined and a variety of pathological lesions were detected, including cutaneous neoplasms and ulceration, acute and chronic tendon lesions and pathologic features of the bone and wrist. Based on the excellent imaging of anatomic detail and superior contrast resolution, high resolution MRI proved an important complement for preoperative diagnosis.

Adult↗
PubMed1994

[Fat suppression in contrast-enhanced MRT of the base of the skull and of the head-neck area: its clinical value].

167 patients with abnormalities at the skull base and at the cervical-skull junction were examined by MRT in order to compare a FATSAT technique with T1- and T2-weighted SE sequences before and after intravenous injection of 0.1 mmol Gd-DTPA/kg KG. The diagnostic information from corresponding FATSAT and T1-SE sequences was correlated with the histopathological findings. In 10.7% of patients fat suppression was inadequate and in a further 11.3% of patients chemical shift artifacts limited the diagnostic value. The number of detectable lesions was not increased by the use of FATSAT sequences but visualisation of soft tissue lesions was improved, adding to the diagnostic value under specific conditions. Evaluating by the Friedman and Wilcoxon test showed that the postcontrast FATSAT sequences were markedly superior (p < 0.01) in delineating and contrasting the lesions. The additional use of contrast enhanced FATSAT sequences resulted in improved diagnosis of lesions at the skull base and the facial skeleton.

Adipose Tissue↗
PubMed1994

[The spiral CT of cervical lymph node enlargements. The initial clinical results].

Spiral CT was performed before treatment in 35 patients with suspected cervical lymph node enlargement. By coronary and sagittal reconstruction it is possible to utilise the M/Q quotient which has become accepted as the result of sonographic and MRI examinations. It is now possible to obtain high diagnostic accuracy (97%) for distinguishing between reactive change from metastatic infiltration of lymph nodes (> 8 mm) by using CT. Using spiral CT with 5 mm table movement, three patients diagnosed as stage N1 by axial CT were shown to be N2b. This represents a highly sensitive and highly specific method of lymph node diagnosis. Further diagnostic improvement derives from the ability to relate the lymph nodes to surrounding tissues. Spiral CT is also suitable for defining other space occupying lesions, e.g., the exact extent of retropharyngeal abscesses, abnormalities of the salivary glands or laryngoceles.

Abscess↗
PubMed1994

[The use of the T2-weighted turbo-spin-echo sequence in studying the neurocranium. A comparison with the conventional T2-weighted spin-echo sequence].

T2-weighted spin-echo imaging is the standard screening procedure in MR imaging of the neurocranium. We evaluated fast spin-echo T2-weighted imaging (TT2) of the neurocranium in comparison to conventional spin-echo T2-weighted imaging (T2). Signal-to-noise and contrast-to-noise ratio of normal brain tissues (basal ganglia, grey and white matter, CSF fluid) and different pathologies were calculated. Signal-to-noise ratio and contrast-to-noise ratio were significantly higher in TT2 than in T2 (with the exception of gray-to-white matter contrast). Tissues with increased content of water protons (mobile protons) showed the highest contrast to surrounding tissues. The increased signal intensity of fat must be given due attention in fatty lesions. Because the contrast-to-noise ratio between white matter and basal ganglia is less in TT2, Parkinson patients have to be examined by conventional T2. If these limitations are taken into account, fast spin-echo T2-weighted imaging is well appropriate for MR imaging of the neurocranium, resulting in heavy T2-weighting achieved in a short acquisition time.

Adult↗
PubMed1994

[Osteoplastic bone metastases in prostatic carcinoma: magnetic resonance tomography and bone marrow scintigraphy].

MRI of the vertebral column was performed in 28 patients with histologically confirmed prostate carcinoma. Besides routine spin-echo sequences all patients were examined with gradient-echo sequences using the chemical shift mode. In addition, in all patients bone marrow scintigraphy (BMS) was performed, and all results were compared with routine bone scan (BS). In our study BMS was not superior to bone scan. In contrast, MRI scan revealed solitary metastases in two patients with negative BS and BMS. Osteoplastic metastases showed a contrast enhancement in the MRI and could be distinguished from benign alterations.

Aged↗
PubMed1994

[CT angiography and arterial DSA in the evaluation of occlusive processes in pelvic arteries. Initial results].

UNLABELLED: 32 patients with iliac artery stenosis and occlusion were studied by means of CT angiography. The results were compared with the results of intraarterial digital subtraction angiography (DSA). Postprocessing was performed with Maximum Intensity Projection (MIP) and 3-D-display. RESULTS: 1. MIP: 27/37 stenoses/occlusions were correctly assessed, underestimation of 5 stenoses/occlusions (4 stenoses, one occlusion), overestimation of 5 stenoses. 2. 3-D-Display: 22/37 stenoses/occlusions were correctly assessed, underestimation of 9/37 (8 stenoses, one occlusion), two false negative results (one stenosis, one occlusion), overestimation of 4/37 stenoses. The MIP technique proved to be the only method to display the localisation of vascular calcifications with their exact topographical relationship to the stenoses and occlusions. MIP also proved to be valuable in controlling the position of intravascular stents. Complementary to DSA, the MIP method therefore seems to be a clinically valuable technique for calcified and noncalcified stenoses.

Adult↗
PubMed1994

[Color-coded duplex sonography in the differential diagnosis of cervical lymph node enlargements].

55 patients with cervical lymph node enlargement were studied prospectively by colour coded duplex sonography. The aim was to demonstrate the perfusion of individual lymph nodes and to determine whether the resistance and pulsatile index are able to show the cause of the enlargement. The lymph nodes were subsequently examined histologically. Useful perfusion measurements were obtained in 177 lymph nodes out of 216. Perfusion index < 1.6 and resistance index < 0.8 distinguishes between reactive lymph node enlargement and lymph node metastases with an accuracy of 91%. Reliable differentiation between lymphoma and metastases was not possible. Tuberculous lymph nodes and cysts showed significantly reduced resistance and pulsatile index when compared with metastases. Further information on the type of disease was obtained from the perfusion patterns. Reactive lymph nodes showed increased central perfusion of the hilum, whereas metastases tended to show increased peripheral perfusion.

Diagnosis, Differential↗