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Biomedical subjects

R Felix

Publications and source records attributed to R Felix.

At least 199 records · Page 11Linked to original sources
PubMed1999

[How can Romberg disease be evaluated by means of MRI?].

Romberg disease, also known as progressive facial hemiatrophy (PFH), is an uncommon disease with progressive facial asymmetry as the major symptom. It is a atrophic process of the subcutaneous fatty tissue whose etiology is unknown. Skin, muscles and bones can be secondarily afflicted. With MRI evaluation we were able to show in 14 patients with PFH thinner subcutaneous fat, as well as flattening of the dermis in 12 of the 14. We divided the patients into three stages by the means of the MRI findings and found tendency towards concurrence between the MRI stage and the clinical stage.

Adolescent↗
PubMed1999

[Diagnostic value of signal-enhanced color Doppler sonography in reactively enlarged lymph nodes].

PURPOSE: This prospective study was performed to investigate characteristic sonomorphological features and vascularity of reactively enlarged lymph nodes. METHOD: We examined 40 patients with enlarged lymph nodes of the neck by Doppler sonography before and after administration of an ultrasound signal-enhancing agent. Peak flow velocity, pulsatility- and resistant indices were assessed. Lymph nodes were sonomorphologically classified into three groups: homogeneous parenchyma (1), a centrally located echogenoic line (2) and an echogenoic "hilus reflex" (3). The quantitative and qualitative criteria were compared to histological findings. RESULTS: A total of 15 lymph nodes appeared homogeneous. A centrally located echogenoic line was found in 17 (42.5%) nodes and echogenoic "hilus reflex" in 8 (20%). These sonomorphological patterns correlate to hilus fibrosis in the histological specimen. In 32.5% (13) of the nodes the analysis of vascularity was possible only after application of the galactose-based ultrasound signal enhancer. Quantitative analysis did not result in specific new aspects. CONCLUSIONS: Reactive lymph nodes show typical sonomorphological features. Administration of an ultrasound enhancer allows assessment of a characteristic nodal vascualrity.

Humans↗
PubMed1999

[Mn-TPPS4 in the diagnosis of malignant skin tumors. In vivo studies with high resolution magnetic resonance tomography in melanotic melanoma].

PURPOSE: Some authors postulate an avidity of certain porphyrin derivatives for tumors. The aim of this study was to examine the contrast enhancement of implanted melanotic melanoma after application of Mn-TPPS4 to achieve a better characterization of this malignant skin tumor. MATERIAL AND METHOD: High-resolution MR imaging (2.0 Tesla, 2.0-cm surface-coil, T1-weighted FLASH-2D-sequence) was performed on 15 mice (C57b16) with intracutaneous implanted melanoma (B16F1), before and after intravenous administration of either Gd-DTPA (Magnevist, Schering, Berlin) as a reference contrast medium, or Mn-TPPS4 (Porphyrin Products, Schering, Berlin). The images were evaluated quantitatively by calculating percentage enhancement, slope of signal intensity-to-time curves, percentage increase of the signal intensity, signal-to-noise and contrast-to-noise-ratios. The qualitative evaluation was accomplished by visual assessment of the enhancement, the demarcation of the tumors from the surrounding tissue and the homogeneity of the tumors. RESULTS: Contrast medium-enhanced images showed an increased signal intensity from all tumors with no signifikant difference between the contrast media. Demarcation of tumors from the surrounding tissue was better following administration of contrast media; regressive and altered areas was more clearly depicted. CONCLUSION: A specific accumulation of the metalloporphyrin Mn-TPPS4 in melanotic melanoma could not be proved. Based on the small and insignifikant differences in the results obtained with the two contrast media, and on the side effects of the metalloporphyrin, the usefulness of Mn-TPPS4 as a contrast medium for MRT is limited.

Animals↗
PubMed1999

Contribution of color and power Doppler sonography to the differential diagnosis of acute and chronic rejection, and tacrolimus nephrotoxicity in renal allografts.

The aim of the present study was to differentiate acute rejection, chronic rejection, and tacrolimus nephrotoxicity with color and power Doppler imaging of renal transplants. One hundred examinations were obtained from 45 patients. Pulsatility and resistive indices were calculated from color Doppler images. The grade of renal vascularization was quantified using computer-assisted pixel analysis in a rectangular region-of-interest. The percentage of vessel-covered renal parenchyma (POV) was calculated using a histogram that discriminated renal vessels from renal parenchyma via power Doppler images. Furthermore, the distance from the most peripherally located vessels to the renal capsule (PVD) was measured. A reduced POV < or = 55% proved to be the best discriminator when chronic rejection was suspected (sensitivity 79%, specificity 87%). Tacrolimus nephrotoxicity showed not only a moderate elevation of the Doppler signal but also an increased PVD > or = 3.9 mm and a normal POV. We conclude that the evaluation of renal vessels by power Doppler images improves diagnostic accuracy for patients with renal allografts.

Acute Disease↗
PubMed1999

High-resolution conjunctival contrast-enhanced MRI dacryocystography.

We assessed high-resolution MRI of the lacrimal system with conjunctival contrast enhancement in patients with suspected stenosis. We studied 18 patients with epiphora affecting 22 eyes, using a surface coil, before and after conjunctival and intravenous Gd-DTPA. Stenosis or obstruction of the ducts was found in 18 of 22 cases: at canalicular level in 3 cases, at the sac in 7 cases, and in the nasolacrimal duct in 8 cases. Periductal pathology following surgery to the maxillary sinus or dacryocystorhinostomy was seen in three cases. In conjunction with the findings on syringing and/or conventional dacryocystography, the narrowing was classified as stenosis or obstruction.

Adult↗
PubMed1999

A new ultrasound-based method for the assessment of torsional differences following closed intramedullary nailing of femoral fractures.

OBJECTIVE: A torsional difference of more than 15 degrees is found in up to 30% of patients following closed intramedullary nailing of femoral fractures. The diagnosis is usually established postoperatively by computed tomography. A torsional deformity of more than 15 degrees should be corrected by early derotation. In order to enable an intraoperative control and possible correction to avoid a second operation for the patient, a new ultrasound-based method suitable for the intraoperative setting has been developed, using the anterior condylar line as a distal reference line. DESIGN AND PATIENTS: In a prospective study the torsional difference after closed intramedullary nailing of femoral fractures was measured postoperatively by ultrasound in 32 patients and compared with standard CT readings. RESULTS: Torsional differences measured by ultrasound and CT showed a high correlation (r = 0.8) and a median difference of less than +/-3 degrees. CONCLUSIONS: By the introduction of the anterior condylar line as a distal reference line femoral torsion can accurately be assessed by ultrasound in a position required for intraoperative control and possible correction.

Adolescent↗
PubMed1999

Focal liver lesions: Doppler ultrasound.

Echo patterns of focal liver lesions as well as other morphological criteria do not suffice for differential diagnosis. In an attempt to increase the specificity of ultrasound of focal liver lesions, several years of Doppler-flow information was evaluated. Recent advances in ultrasound technology (power Doppler imaging, second harmonic imaging) as well as commercial availability of an intravenous signal enhancer (contrast agent) have additionally improved results of this technique.

Aged↗
PubMed1999

[Evaluation of polyurethane stent implantation for the treatment of complete obstruction of the nasolacrimal system: 8-month follow-up and complications].

UNLABELLED: Dacryocystorhinostomy is still the standard procedure complete stenosis of the nasolacrimal duct. New methods try to preserve the natural lacrimal pathway. Song implanted in 1995 a nasolacrimal polyurethane stent through the nasolacrimal duct. The results and complications of this new method are described in this prospective study. METHODS: Thirty consecutive patients with complete obstruction of the nasolacrimal duct or lacrimal sac were included in the study. The stenosis was localized by dacryocystography. The ages ranged from 22 to 87 years (mean, 58.9 +/- 16 years). Dacryocystography was performed immediately, 4 weeks and 8 months after the procedure to verify the position and patency of the stent. RESULTS: Twenty-five short (35 mm) and 5 long (45 mm) stents were implanted. Twenty-four of 30 patients after 4 weeks and 9 of 10 patients after 8 months had reduced or no complaints. In 1 patient the stent was obstructed. Forceful irrigation with saline solution permitted recanalization. In 1 patient the stent had moved into the upper canaliculus. Because of irritation of the canaliculus it had to be pulled out after 2 months. CONCLUSION: The follow-up is still too short to recommend stent implantation as a real alternative to dacryocystorhinostomy. The main advantages are that the procedure is faster, no incision is necessary, and the local anesthesia is easier. The disadvantage is the need for X-ray examination.

Adult↗
PubMed1999

Comparison of various imaging methods with particular evaluation of color Doppler sonography for planning surgery for breast tumors.

OBJECTIVE: Color Doppler sonography (CD) was compared with other diagnostic imaging methods [mammography (MG), breast ultrasound (US) and magnetic resonance imaging (MRI)] in the planning of surgery for breast tumors. MATERIALS AND METHODS: 99 patients with breast cancer and 101 with ultimately benign breast lesions were examined preoperatively. The specificity and sensitivity were calculated, as well as the predictive values. Various qualitative and semiquantitative CD parameters were also analysed for their diagnostic value. RESULTS: The sensitivity/specificity of the various methods (in %) was: MG 85/77; US 95/80; CD 82/75; MRI 90/63. The positive predictive value (ppv)/negative predictive value (npv) (in %) was: MG 79/83; US 81/94; CD 72/84; MRI 79/63. The median maximum systolic flow velocity and the resistance index (RI) were significantly higher in breast cancer vessels than in benign lesions. The number of pulsating color pixels detected by CD was significantly higher for breast cancer. In cases of breast cancer significantly more blood flows were detected in the body of the tumor than at its periphery. CONCLUSION: Color Doppler sonography was not superior to other diagnostic methods for preoperative assessment of a breast lesion. The combination of all diagnostic procedures gave a correct classification rate of 93.3% and is much better than the correct classification of any single diagnostic imaging procedure.

Aged↗
PubMed1999

Accuracy of endorectal ultrasound after preoperative radiochemotherapy in locally advanced rectal cancer.

OBJECTIVES: Factors limiting the accuracy of endorectal ultrasound in staging, locally advanced primary rectal cancer after preoperative neoadjuvant radiochemotherapy (RCT) were evaluated. METHODS: Patients (n = 84) with initial locally advanced rectal cancer (uT3/uT4) undergoing R0 resection were investigated after preoperative treatment that combined radiotherapy up to 45 Gy with two cycles of chemotherapy (5-FU and leucovorin on d 1-5 and 22-28). At 4 to 6 weeks after completion of RCT and before tumor resection, preoperative endoluminal ultrasound was performed. RESULTS: The accuracy to predict the depth of tumor infiltration (T-category) was found to correlate with downstaging. The T-category was correctly staged before surgery in 15 of the 51 responders (29%) and in 27 of 33 nonresponders (82%), whereas misinterpretation occurred in 36 of the responders (71%) and in 6 of the nonresponders (18%) (p < 0.001). Neither tumor distance from anal verge nor tumor location correlated with the staging accuracy. Lymph node involvement was correctly assessed in 48 patients (57%). Wall invasion was correctly ascertained in 42 patients (50%), with under estimation in 11 patients (13%) and overestimation in 31 patients (37%). CONCLUSIONS: After radiochemotherapy, endosonography does not provide a satisfactory accuracy for preoperative staging of rectal cancer. New interpretation and diagnostic criteria are needed for the prediction of treatment response.

Adenocarcinoma↗
PubMed1999

[A prospective study on the detection of lesions of the labrum glenoidale by indirect MR arthrography of the shoulder].

PURPOSE: Aim of this prospective study was the evaluation of signal-alterations of anatomic shoulder structures before and after intravenous application of Gd-DTPA. Furthermore the tested clinical value of indirect MR-arthrography in detecting labrum lesions was tested. MATERIAL AND METHODS: 52 patients with suspected shoulder injury were examined on a 1.5 T system: Sequences were T1-weighted axial and oblique-coronary, additionally oblique-coronary T2-weighted, PD-weighted- and axial FLASH-2D-Sequences. After intravenous injection of contrast medium T1-weighted sequences were repeated. Signal-intensities (SI) of anatomic structures were measured by ROI-technique, the percentual contrast-enhancement (CE) and alterations in SNR (signal-noise-ratio) and CNR (contrast-noise-ratio) were calculated. Labrum tears were graded by three observers, their results could be confirmed by arthroscopy or open surgery in 24 patients. RESULTS: Contrast-enhancement was shown in all structures, most remarkable in the joint cavity. In pathologic findings of the labrum the SI and CE were significantly higher compared to intact strictures (p < 0.05). Sensitivity and specificity in the detection of labrum tears were 70% and 71.4% without contrast media, respectively 100% and 71.4% with indirect arthrography. CONCLUSIONS: The indirect arthrography improves the signal parameters of the structures. The detection of labrum lesions is improved, but still remains difficult.

Adolescent↗
PubMed1999

[Automated speech recognition for the generation of medical records in computed tomography].

PURPOSE: A study was performed to compare the performance of automatic speech recognition (ASR) with conventional transcription. MATERIALS AND METHODS: 100 CT reports were generated by using ASR and 100 CT reports were dictated and written by medical transcriptionists. The time for dictation and correction of errors by the radiologist was assessed and the type of mistakes was analysed. The text recognition rate was calculated in both groups and the average time between completion of the imaging study by the technologist and generation of the written report was assessed. A commercially available speech recognition technology (ASKA Software, IBM ViaVoice) running on a personal computer was used. RESULTS: The time for the dictation using digital voice recognition was 9.4 +/- 2.3 min compared to 4.5 +/- 3.6 min with an ordinary Dictaphone. The text recognition rate was 97% with digital voice recognition and 99% with medical transcriptionists. The average time from imaging completion to written report finalization was reduced from 47.3 hours with medical transcriptionists to 12.7 hours with ASR. The analysis of misspellings demonstrated (ASR vs. medical transcriptionists): 3 vs. 4 for syntax errors, 0 vs. 37 orthographic mistakes, 16 vs. 22 mistakes in substance and 47 vs. erroneously applied terms. CONCLUSIONS: The use of digital voice recognition as a replacement for medical transcription is recommendable when an immediate availability of written reports is necessary.

Algorithms↗
PubMed1999

[The value of magnetic resonance tomography (MRT) for evaluating ventricular and anastomotic functions in patients with an extra- or intracardiac total cavopulmonary connection (TCPC)-modified Fontan operation].

PURPOSE: To evaluate different MR methods (ventricle and flow measurements) for the postoperative follow-up of hemodynamics in patients with extra- or intracardial TCPC. MATERIALS AND METHODS: Twenty-eight consecutive patients (14 female, 14 male) within the ages of two to thirty-eight years were examined using a 1.5 T Gyroscan ACS-NT scanner (Philips, Best, Netherlands). 7 patients had an extracardial (eTCPC), and 21 an intracardial (iTCPC) tunnel. The calculation of the ventricular function and muscle mass was performed using "multislice-multiphase" technique by summing up the end-diastolic and end-systolic areas; the flow measurements were evaluated by phase shift velocity mapping in the superior vena cava (SVC), inferior vena cava (IVC), right (RPA) and left (LPA) pulmonary artery. Besides peak and mean velocity, the mean and maximal flow volumes (ml/min) were calculated. RESULTS: Ejection fraction (EF) of the functionally single ventricle was within the normal range (mean 57%) in 22/28 patients while mean muscle mass was elevated in the group with eTCPC (mean 121 g/m2). The mean flow volumes and the peak velocities in all vessels were higher in the group with iTCPC as compared to the one with eTCPC. Clinically relevant retrograde flows in the IVC were only found in the group with iTCPC (7/21), as well as a significant predominant flow distribution towards the RPA (p < 0.05; Wilcoxon signed-rank test); in the group with eTCPC towards the LPA (n.s.). CONCLUSIONS: MRI is a useful method for the assessment of ventricular function and muscle mass in the follow-up after the modified Fontan operation. MRI flow measurements additionally provided clinically relevant information about the hemodynamics in Fontan patients.

Adolescent↗
PubMed1999

[Malignant lymphoma: magnetic resonance tomography findings in residual supradiaphragmatic space-occupying lesions].

PURPOSE: Evaluation of MR imaging in patients with Hodgkin's lymphoma and high grade non-Hodgkin's-lymphoma and mediastinal residual mass after first line chemotherapy. MATERIALS AND METHODS: MR imaging (1.5 T) was performed in 36 patients (Hodgkin's lymphoma n = 26, NHL n = 10) after first line chemotherapy). Twenty patients had inactive residual mass, 16 patients had residual lymphoproliferative lesions. T1- and T2-weighted spin echo images were visually analysed by a score index (range 1-5) as well as quantification of enhancement by signal-intensity-ratios SImax/SIplain). RESULTS: For the differentiation between residual lymphoproliferative activity and inactive residual mass, the highest accuracy was obtained for the signal intensity of residual mass on T2-w-SE compared to pectoralis muscle (94% sensitivity, 80% specificity, likelihood ratios: 4.0 [LR+]; 0.3 [LR-]). The cut-off value of the SI ratio was calculated retrospectively at 1.96 (p > 0.05). CONCLUSIONS: Differentiation between inactive (fibrotic) and lymphoproliferative (active) residual mediastinal mass is possible by MR imaging using as parameter the size reduction after therapy and the signal intensity on T2-w-SE in comparison to pectoralis muscle. Thus study suggests an additional value using the SI ratio for the differentiation.

Adult↗