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Biomedical subjects

C Fink

Publications and source records attributed to C Fink.

At least 19 recordsLinked to original sources
PubMed2006

Interventional magnetic resonance imaging: an alternative to image guidance with ionising radiation.

At present, interventional procedures, such as stent placement, are performed under X-ray image guidance. Unfortunately with X-ray imaging, both patient and interventionalist are exposed to ionising radiation. Furthermore, X-ray imaging is lacking soft tissue contrast and is not capable of true 3-D displays of either interventional device or tissue morphology. Magnetic resonance imaging (MRI) offers excellent soft tissue contrast, 3-D acquisition techniques, as well as rapid image acquisition and reconstruction. Despite these advantages, MR-guided interventions are challenging owing to the limited access to the patient, strong magnetic and radio-frequency fields that require special interventional devices, inferior image frame rates and spatial resolution, and high MRI scanner noise. For MR-guided intravascular interventions, where access to the target organ is achieved through catheters, dedicated hardware and automated image slice positioning techniques have been developed. We illustrate that MR-guided renal embolisations can be performed in closed-bore high-field MR scanners.

Animals↗
PubMed2006

[MRI of pulmonary perfusion].

Lung perfusion is a crucial prerequisite for effective gas exchange. Quantification of pulmonary perfusion is important for diagnostic considerations and treatment planning in various diseases of the lungs. Besides disorders of pulmonary vessels such as acute pulmonary embolism and pulmonary hypertension, these also include diseases of the respiratory tract and lung tissue as well as pulmonary tumors. This contribution presents the possibilities and technical requirements of MRI for diagnostic work-up of pulmonary perfusion.

Humans↗
PubMed2006

Serotonin-containing cells in the gastrointestinal tract of newborn foals and adult horses.

Serotonin (5-hydroxytryptamine, 5-HT), a regulatory amine of mucosal enterochromaffin cells plays an important role in the control of gastrointestinal smooth muscle contraction and epithelial secretion. Serotonin has also been associated with gastric ulcers, diarrhoea and abdominal pain. In spite of the high incidence of these gastrointestinal disorders in newborn foals and adult horses, no data are available regarding 5-HT immunoreactive cells (i.c.) in the gastrointestinal tract (GIT) of foals, and for adult horses, data are incomplete and contradictory. In this study, the distribution and relative frequency of 5-HT i.c. in the GIT of newborn foals and adult horses were determined immunohistochemically. In foals as in adults, a relatively large number of 5-HT i.c. were detected in all portions of the GIT. In foals, a significantly higher amount of cells was found in the pyloric region and margo plicatus of the stomach, as well as in the caecum and colon ascendens compared with adults. Our results provided rationale for further research concerning the role of 5-HT i.c. during the milk diet or in the regulation of gastrointestinal growth/cell proliferation, and in the pathogenesis of gastric ulcers, especially in newborn foals.

Animals↗
PubMed2005

Bony and cartilaginous anatomy of the patellofemoral joint.

The patella as the largest sesamoid bone of the human body forms the patellofemoral joint with the patellar groove of the femur. The patellofemoral joint is a complex articulation with high functional and biomechanical requirements. Several anatomical variants of both patella and the trochlea exist. Multiple clinical problems of the knee may be caused by anatomical and physiological abnormalities of this joint. Exact knowledge about the anatomy, the biomechanics and the function of the patellofemoral joint is therefore required to understand its wide range of pathology.

Bone Diseases, Developmental↗
PubMed2005

Time-resolved echo-shared parallel MRA of the lung: observer preference study of image quality in comparison with non-echo-shared sequences.

The aim of this study was to evaluate the image quality of time-resolved echo-shared parallel MRA of the lung. The pulmonary vasculature of nine patients (seven females, two males; median age: 44 years) with pulmonary disease was examined using a time-resolved MRA sequence combining echo sharing with parallel imaging (time-resolved echo-shared angiography technique, or TREAT). The sharpness of the vessel borders, conspicuousness of peripheral lung vessels, artifact level, and overall image quality of TREAT was assessed independently by four readers in a side-by-side comparison with non-echo-shared time-resolved parallel MRA data (pMRA) previously acquired in the same patients. Furthermore, the SNR of pulmonary arteries (PA) and veins (PV) achieved with both pulse sequences was compared. The mean voxel size of TREAT MRA was decreased by 24% compared with the non-echo-shared MRA. Regarding the sharpness of the vessel borders, conspicuousness of peripheral lung vessels, and overall image quality the TREAT sequence was rated superior in 75-76% of all cases. If the TREAT images were preferred over the pMRA images, the advantage was rated as major in 61-71% of all cases. The level of artifacts was not increased with the TREAT sequence. The mean interobserver agreement for all categories ranged between fair (artifact level) and good (overall image quality). The maximum SNR of TREAT did not differ from non-echo-shared parallel MRA (PA: TREAT: 273+/-45; pMRA: 280+/-71; PV: TREAT: 273+/-33; pMRA: 258+/-62). TREAT achieves a higher spatial resolution than non-echo-shared parallel MRA which is also perceived as an improved image quality.

Adolescent↗
PubMed2005

[ACL reconstruction with bone-patellar tendon-bone graft and proximal fixation with the EndoButton: a 2- to 5-year follow-up].

BACKGROUND: Interference screw fixation in ACL reconstruction with bone-patellar tendon-bone graft (BPTB) is a potential source of intraoperative complications such as graft laceration. Further problems are artifacts on MRI and screw removal in revision surgery. These problems can be avoided by using distant fixation with the EndoButton. We designed this study to evaluate the clinical as well as the subjective outcome of ACL reconstruction with BPTB graft and femoral fixation with the EndoButton. METHODS: A total of 51 patients (7 female, 44 male) were examined 2-5 years after ACL reconstruction with BPTB graft and femoral fixation with the EndoButton. We used the IKDC form, Lysholm score, Tegner activity score, and digital radiographs (AP, lateral, axial) for the evaluation. RESULTS: Of all the patients included in the study, 87% showed a "normal" or "nearly normal" knee function according to the IKDC score, Lysholm score 94.2+/-7.9, Tegner score 6.4+/-1.2, and subjective IKDC 89.9+/-11.9. Radiological signs of arthritic changes could be seen in ten cases. CONCLUSION: The clinical outcome of ACL reconstruction with EndoButton fixation is comparable to other studies on ACL reconstruction with interference screw fixation. However, since the EndoButton avoids potential problems of the interference screw fixation, we recommend this fixation technique for ACL reconstruction with BPTB graft.

Adolescent↗
PubMed2005

[Multidetector CT for the diagnosis of congenital vascular anomalies and associated complications in newborns and infants].

PURPOSE: To assess the value of multidetector CT (MDCT) for evaluation of vascular anomalies (VA) and associated complications in newborns and infants. MATERIALS AND METHODS: Seventy-five children (mean age: 9 +/- 6 months, range: 2 weeks to 24 months) with VA were examined using MDCT (4-, 8- or 16-row; collimation 0.5-1.25 mm; scan time 7-30 s), which was performed under controlled ventilation or free breathing. Image quality was rated using a 5-point scale. Image findings were correlated to echocardiography, conventional catheter angiography (CCA), bronchoscopy, and intraoperative findings. RESULTS: High quality MDCT data were almost free of cardiac and respiratory motion. In all cases, VA morphology and topography in relation to adjacent structures, e. g. tracheal and esophageal compression caused by an aortic ring, could be assessed exactly and allowed the final diagnosis. Even aberrant vessels, such as aorto-pulmonary collaterals (MAPCA) with a diameter of less than 1 mm, could be identified and excellently visualized. Eighty percent (60/75) of all patients had benefited from the MDCT: in 31 patients CCA was neither necessary to perform surgical planning nor to exclude a VA; in an additional 29 patients radiation doses and sedation time due to interventional procedures could be reduced markedly. CONCLUSIONS: MDCT can now be regarded as the modality of choice as a minimally invasive, robust, and accurate technique for the diagnosis of complex VA, their potentially life-threatening complications and preoperative planning even in newborns and infants. Its accuracy for detecting VA appears equivalent to CCA while it is more accurate in delineating potential life-threatening complications.

Arteriovenous Malformations↗
PubMed2005

Quantitative analysis of lung and tumour mobility: comparison of two time-resolved MRI sequences.

The purpose of this study was to describe the use of parallel imaging technique (PAT) using dynamic MRI in lung and tumour mobility during the breathing cycle. 20 patients with stage I non-small cell lung carcinoma were investigated using two dynamic gradient echo sequences with PAT (TrueFISP (fast imaging with steady precession), and fast low angle shot (FLASH). Craniocaudal distance from the apex to the diaphragm of the thorax and tumour mobility during the breathing cycle were measured. Signal-to-noise ratio (SNR) of the tumour was determined. In spite of the different temporal resolutions both trueFISP and FLASH sequence proved to be adequate to continuously measure lung motion and tumour mobility. SNR of the tumour was significantly higher using the trueFISP sequence than FLASH sequence (20.7+/-3.6 vs 5.8+/-2.3, p<0.01). Mobility of the tumour bearing hemithorax was significantly lower compared with the non-tumour bearing hemithorax (p<0.05). Dynamic MRI using PAT allows for continuous quantitative documentation of tumour mobility and lung motion. Because of the higher SNR, trueFISP sequence provides a better delineation of intrapulmonary lesions with a sufficient temporal resolution.

Aged↗
PubMed2004

Maintenance of remission with leflunomide in Wegener's granulomatosis.

OBJECTIVE: To investigate the safety and efficacy of leflunomide plus low-dose prednisolone for the maintenance of remission in Wegener's granulomatosis (WG). METHODS: This was a Phase II, single-centre, open-label clinical investigation of patients with generalized WG treated with leflunomide after the induction of complete (n = 4) or partial (n = 16) remission by cyclophosphamide/prednisolone combination therapy. Leflunomide treatment was initiated at 20 mg/day and increased to 30 mg/day after 12 weeks and, in patients with partial remission, to 40 mg/day after 24 weeks. Concomitant low-dose prednisolone (< or =10 mg/day) was allowed during the study. In addition to the frequency of relapse, treatment efficacy was assessed by the standard measures of disease activity/extent. RESULTS: A total of 20 patients were enrolled in the trial. During a treatment period of up to 2.5 yr (median 1.75 yr, range 1-2.5 yr), one patient had a major relapse and required retreatment with cyclophosphamide/prednisolone. Eight patients had minor relapses that were successfully treated by dose increases to 40 mg/day leflunomide. Disease activity remained unchanged for the duration of the study. The most frequently reported adverse events were mild respiratory infection (40%), arthralgia (35%) and hypertension (35%); dry skin, nail disorder and diarrhoea were each reported by 30% of patients. Despite the aggressive pretreatment with cyclophosphamide, adverse events with leflunomide treatment at the higher dose (30-40 mg/day) were comparable with those seen with the standard dose (20 mg/day) for rheumatoid arthritis patients. CONCLUSION: Leflunomide appears to be safe and well tolerated for the maintenance of complete or partial remission of WG. The results of this pilot study encourage further controlled trials comparing leflunomide with alternative remission maintenance therapies.

Adult↗
PubMed2004

[MRT of bronchial carcinomas].

Compared to computed tomography (CT), magnetic resonance imaging (MRI) only plays a minor role for the imaging of lung cancer. Among the reasons are technical limitations, such as longer acquisition times or inferior spatial resolution, as well as unfavourable tissue characteristics which cause a low signal-to-noise ratio of the lung parenchyma. However, MRI is a valuable tool for staging lung cancer and may in some cases even be considered the method of choice. The following review illustrates the role of MRI for the diagnosis of lung cancer using current MR-techniques. In particular, the potential of MRI for TNM-staging, new technical developments (e. g. parallel MRI), and the application of functional MRI of the chest are described.

Carcinoma, Bronchogenic↗
PubMed2004

Rings, slings and other vascular abnormalities. Ultrafast computed tomography and magnetic resonance angiography in pediatric cardiology.

Ultrafast CT and MR angiography are noninvasive, accurate and robust techniques for preoperative diagnosis and planning of congenital heart disease and vascular abnormalities in pediatric patients. While they seem to be equivalent to conventional catheter angiocardiography for detecting vascular abnormalities, they are more accurate for the diagnosis of potentially life-threatening complications, such as tracheal, bronchial or esophageal compression. The value of ultrafast CT and MR angiography is demonstrated in 22 pediatric patients with vascular rings, slings and other vascular abnormalities.

Angiography↗
PubMed2004

[Contrast-enhanced 3D MR perfusion of the lung: application of parallel imaging technique in healthy subjects].

PURPOSE: Evaluation of lung perfusion by contrast-enhanced 3D MRI using partial parallel imaging techniques. MATERIALS AND METHODS: Eight healthy volunteers were examined using a contrast-enhanced dynamic FLASH 3D sequence with partial parallel imaging technique at 1.5 T MRI with a TA of 1.5 sec. The whole lung was covered by 36 coronal slices. A ventral, middle and dorsal slice of each lung was manually segmented and signal-to-time curves were computed. For absolute quantification of blood flow through the right and left pulmonary artery, phase-contrast flow measurements were performed. RESULTS: No significant difference was found between the signal intensity in the right (8.9 +/- 2.6) and left (8.0 +/- 3.5) lung, corresponding to a left-to-right signal intensity ratio of 0.9. A significantly higher signal intensity was found in the dorsal regions of the lungs (p = 0.01) compared to the ventral regions. The time to peak of the signal intensity was significantly shorter in the dorsal (15.3 sec) and middle (15.7 sec) regions of the lungs (p = 0.03 and p = 0.04, respectively) than in the ventral regions (16.3 sec). The ratio between blood flow through the left (2.2 L/min) and right (2.7 L/min) lung was 0.84. CONCLUSION: Partial parallel image acquisition can assess the perfusion of the lungs at high temporal resolution. The perfusion is slightly higher on the right than on the left. The signal increases faster and has a higher peak in the dorsal lung regions.

Adolescent↗
PubMed2004

Quantitative analysis of pulmonary perfusion using time-resolved parallel 3D MRI - initial results.

PURPOSE: To assess the use of time-resolved parallel 3D MRI for a quantitative analysis of pulmonary perfusion in patients with cardiopulmonary disease. MATERIALS AND METHODS: Eight patients with pulmonary embolism or pulmonary hypertension were examined with a time-resolved 3D gradient echo pulse sequence with parallel imaging techniques (FLASH 3D, TE/TR: 0.8/1.9 ms; flip angle: 40 degrees; GRAPPA). A quantitative perfusion analysis based on indicator dilution theory was performed using a dedicated software. RESULTS: Patients with pulmonary embolism or chronic thromboembolic pulmonary hypertension revealed characteristic wedge-shaped perfusion defects at perfusion MRI. They were characterized by a decreased pulmonary blood flow (PBF) and pulmonary blood volume (PBV) and increased mean transit time (MTT). Patients with primary pulmonary hypertension or Eisenmenger syndrome showed a more homogeneous perfusion pattern. The mean MTT of all patients was 3.3 - 4.7 s. The mean PBF and PBV showed a broader interindividual variation (PBF: 104 - 322 ml/100 ml/min; PBV: 8 - 21 ml/100 ml). CONCLUSION: Time-resolved parallel 3D MRI allows at least a semi-quantitative assessment of lung perfusion. Future studies will have to assess the clinical value of this quantitative information for the diagnosis and management of cardiopulmonary disease.

Acute Disease↗
PubMed2003

Development of the glandular epithelium of the bovine parotid gland during ontogenesis.

The development of the parotid gland was examined in 36 bovine embryos and foetuses with a crown-rump-length (CRL) from 28 up to 1000 mm by light, transmission electron microscopical and actin-immunohistochemical methods. The anlage of the parotid gland in an embryo with 28 mm CRL can be found at the lateral angle of the primitive oral cavity as a local thickening of the epithelium. During the second month, the differentiation of primary ducts and endbuds starts and a lumen develops in the primary ducts. At the end of the second month a lumen appears in the terminal endbuds. In the immature endpiece cells first secretory granules can be seen from a CRL of 240 mm. In the third month differentiation between intra- and inter-lobular ducts is possible. Immature myoepithelial cells present as a basal layer of flattened cells between the epithelial cells and the basement membrane at the end of the second month. During further development they increase in number, become more flattened and form long cellular processes. At the end of the fourth month isolated actin filament bundles are formed, which were also detected by an antibody against smooth muscle actin. The actin filaments condense continuously until they fill the cell processes completely at the end of foetal development.

Animals↗
PubMed2003

[Time-resolved multiphasic 3D MR angiography in the diagnosis of the pulmonary vascular system in children].

PURPOSE: To evaluate time-resolved, multiphasic 3D MR angiography (MRA) for the non-invasive assessment of the pulmonary vascular system in children. MATERIALS AND METHODS: 10 children aged 6 to 15 years (mean age 10 years) ware examined on a 1.5 T whole body MR system with time-resolved, multiphasic 3D MRA after injection of 0.2 mmol/kg body weight of Gd-DTPA. With the use of an ultrafast gradient echo pulse sequence with asymmetric k-space filling and very short echo and repetition times, a nominal spatial resolution of 1.4 x 1.4 x 2.0 mm3 could be achieved with a scan time of 5.6 and 6.2 seconds for a single 3D data set. Two radiologists, who were blinded to the clinical diagnosis, analyzed the image data in consensus. The image analysis included the assessment of the image contrast and artifacts as well as a quantitative analysis of the signal-to-noise (SNR) and contrast-to-noise ratios (CNR) for central and peripheral lung vessel segments. RESULTS: The children tolerated all examinations without any side effects. The referral diagnosis, which was based on echocardiography, catheter angiography and surgery, was confirmed by MRA in all cases. The image contrast was rated at least satisfactory in all but one case (19 of 20) and no artifacts were observed. The quantitative analysis of the SNR and CNR in the pulmonary arteries and veins confirmed the reader analysis of a high and uniform contrast throughout the entire pulmonary circulation. CONCLUSION: Time-resolved multiphasic 3D MRA allows a non-invasive diagnostic evaluation of the pulmonary circulation in children. In view of the excellent image quality, MRA may replace conventional diagnostic catheter angiography in the near future.

Adolescent↗
PubMed2002

Accuracy of tumor size measurement in breast cancer using MRI is influenced by histological regression induced by neoadjuvant chemotherapy.

The aim of this study was to evaluate whether regressive changes after neoadjuvant chemotherapy for breast cancer affect the accuracy of preoperative MRI measurements of tumor size. Thirty-one patients with breast cancer underwent MRI before and after neoadjuvant treatment. Besides pre- and post-contrast T1-weighted MRI, dynamic MRI with high temporal resolution (turbo-FLASH) was performed. Contrast enhancement in dynamic MRI was quantified using a pharmacokinetic two-compartment model, where two parameters, amplitude and k(ep), were calculated and color coded on transversal parameter maps. Considering the conventional MR images, tumor diameters were measured on the color maps and compared with histological tumor size. Histological regression was scored on a five-point scale regarding cytopathic effects, reactive changes, and tumor cell reduction. The correlation between tumor sizes measured by MRI and histopathology was 0.83 ( p<0.0007) in 12 tumors without regressive changes (score 0), and 0.48 ( p<0.051) in 17 tumors with regressive changes scored 1 or 2, without any tendency for systematic over- or underestimation. In two cases without residual tumor (score 4), MRI likewise showed no signs of persistent tumor. The decrease of the contrast enhancement parameters was significantly more marked in tumors with signs of histological regression than in those without. Whenever MRI is used to judge the response of breast cancer to chemotherapy, the reader must be aware that therapy-induced changes may cause significant over- or underestimation of tumor size. We saw a high precision only when there was either no response - according to histological criteria - or when the tumor had regressed completely.

Antineoplastic Agents↗