Biomedical subjects

Claus D Claussen

Publications and source records attributed to Claus D Claussen.

At least 55 records · Page 3Linked to original sources

PubMed2006

Relaxivity of Gadopentetate Dimeglumine (Magnevist), Gadobutrol (Gadovist), and Gadobenate Dimeglumine (MultiHance) in human blood plasma at 0.2, 1.5, and 3 Tesla.

OBJECTIVES: We sought to determine the relaxivity and accurate relaxation rates of Gd-DTPA, Gd-BT-DO3A, and Gd-BOPTA at 0.2, 1.5, and 3 T in human blood plasma. MATERIALS AND METHODS: Contrast media concentrations between 0.01 and 16 mM in human plasma were used for relaxation measurements. The R1 and R2 relaxation rates and r1 and r2 relaxivities were determined. RESULTS: Gd-BOPTA produced the highest relaxation rates and relaxivities at all field strengths. The r1 and r2 values for Gd-BOPTA were 107-131% and 91-244% higher than for Gd-DTPA, respectively, and 72-98% and 82-166% higher than for Gd-BT-DO3A. Higher field strengths resulted in lower values of R1, R2, and r1 for all contrast agents tested and of r2 for Gd-DTPA and Gd-BT-DO3A. A linear dependence of R1 and R2 on concentration was found for Gd-DTPA and Gd-BT-DO3A and a nonlinear dependence for Gd-BOPTA for concentrations larger than 1 mM. The r1 and r2 relaxivity of Gd-BOPTA increased with decreasing concentration. CONCLUSIONS: Gd-BOPTA demonstrates the highest longitudinal r1 at all field strengths, which is ascribable to weak protein interaction. The R2/R1 ratio increases at higher field strength only for Gd-BOPTA, hence very short echo times are required for Gd-BOPTA to benefit from the higher longitudinal relaxivity.

Contrast Media↗

PubMed2006

Monitoring of lung motion in patients with malignant pleural mesothelioma using two-dimensional and three-dimensional dynamic magnetic resonance imaging: comparison with spirometry.

PURPOSE: To monitor lung motion in patients with malignant pleural mesothelioma (MPM) before and after chemotherapy (CHT) using 2-dimensional (2D) and 3-dimensional (3D) dynamic MRI (dMRI) in comparison with spirometry. METHODS AND MATERIALS: Twenty-two patients with MPM were examined before CHT, as well as after 3 and 6 CHT cycles (3 months and 6 months) using 2D dMRI (trueFISP; 3 images/s) and 3D dMRI (FLASH 3D, 1 slab (52 slices)/s) using parallel imaging in combination with view-sharing technique. Maximum craniocaudal lung dimensions (2D) and lung volumes (3D) were monitored, separated into the tumor-bearing and nontumor-bearing hemithorax. Vital capacity (VC) was measured for comparison using spirometry. RESULTS: Using 2D technique, there was a significant difference between the tumor-bearing and the nontumor-bearing hemithorax before CHT (P < 0.01) and after 3 CHT cycles (P < 0.05), whereas difference was not significant in the second control. In the tumor-bearing hemithorax, mobility increased significantly from the status before versus after 3 CHT cycles (4.1 +/- 1.1 cm vs. 4.8 +/- 1.4 cm, P < 0.05). Using 3D technique, at maximum inspiration, the volume of the tumor-bearing hemithorax was 0.6 +/- 0.4 L and of the nontumor-bearing hemithorax 1.25 +/- 0.4 L before CHT. In the follow-up exams, these volumes changed to 1.05 +/- 0.4 L (P < 0.05) and 1.4 +/- 0.5 L, respectively. Using spirometry, there was no significant change in VC (1.9 +/- 0.4 L vs. 2.2 +/- 0.7 L vs. 2.2 +/- 0.9 L). CONCLUSION: dMRI is capable of monitoring changes in lung motion and volumetry in patients with MPM not detected by global spirometry. Thus, dMRI is proposed for use as a further measure of therapy response.

Aged↗

PubMed2006

MR-guided radiofrequency ablation: do magnetic fields influence extent of coagulation in ex vivo bovine livers?

PURPOSE: To prospectively determine if static magnetic fields of magnetic resonance (MR) imagers affect radiofrequency (RF) ablation coagulation volume and shape. MATERIALS AND METHODS: Ex vivo RF ablations of bovine livers were performed with magnetic field strengths of 0.2, 1.5, and 3.0 T and were compared with ablations performed outside the magnetic field in a control group. Two MR-compatible monopolar RF devices (internally cooled single and cluster electrodes) were systematically tested. Length of long axis (y-axis), length of two short axes (x- and z-axes), and coagulation volume and shape measured outside and inside different magnetic fields were compared with the Dunnett test. Significance level was set to .05. RESULTS: For the single electrode, no significant difference was observed between length of short axes and coagulation volume and shape measured inside and outside the magnetic field. Mean x- and z-axis lengths were 2.3 and 2.6 cm, respectively, outside the magnetic field; 2.4 and 2.4 cm, respectively, at 0.2 T; 2.5 and 2.6 cm, respectively, at 1.5 T; and 2.2 and 2.5 cm, respectively, at 3.0 T. Differences between length of long axis, length of short axis perpendicular to static magnetic field, and coagulation volume and shape achieved with the cluster electrode inside and outside the magnetic field were not significant. Mean x- and z-axis lengths were 3.9 and 3.9 cm, respectively, outside the magnetic field; 3.7 and 3.8 cm, respectively, at 0.2 T; 4.0 and 4.3 cm, respectively, at 1.5 T; and 3.8 and 3.8 cm, respectively, at 3.0 T. Differences between ablations performed at 1.5 T and those performed in the control group with the cluster electrode were significant (P = .026). In this case, a difference of 4 mm in the length of the short axis parallel to the magnetic field was detected, but there was no significant difference in coagulation volume. CONCLUSION: No significant differences in coagulation volume and shape could be recorded between RF ablations performed outside and those performed inside the static magnetic field.

Animals↗

PubMed2006

Percutaneous MR-guided radiofrequency ablation of recurrent sacrococcygeal chordomas.

OBJECTIVE: Radiofrequency ablation is emerging as a therapeutic technique for the treatment of an increasing variety of tumors. Exact visual guidance to the tumor and controlled delivery of energy is pivotal for ablation success. CONCLUSION: Introducing MRI as a guidance technique ideally uses tumor-specific tissue characteristics, allows direct multiplanar reconstruction for precise needle positioning, and permits real-time monitoring and assessment of treatment-induced tissue signal changes to increase the safety of the procedure.

Aged↗

PubMed2006

Optimized contrast-enhanced CT protocols for diagnostic whole-body 18F-FDG PET/CT: technical aspects of single-phase versus multiphase CT imaging.

UNLABELLED: The purpose of this study was to compare various PET/CT examination protocols that use contrast-enhanced single-phase or contrast-enhanced multiphase CT scans under different breathing conditions. METHODS: Sixty patients with different malignant tumors were randomized into 4 different PET/CT protocols. Single-phase protocols included an intravenous contrast-enhanced (Ultravist 370; iodine at 370 mg/mL) single-phase whole-body CT scan (90 mL at 1.8 mL/min; delay, 90 s) during shallow breathing (protocol A) or during normal expiration (NormExp; protocol B). Multiphase protocols included 2 separate CT scans in the arterial contrast enhancement phase (90 mL at 2.5-2.8 mL/min; bolus tracking; scan range, base of the skull to the kidneys) and the portal-venous contrast enhancement phase (delay, 90 s; scan range, base of the lungs to the proximal thighs) during shallow breathing (protocol C) or during NormExp (protocol D) followed by a low-dose CT scan during shallow breathing for attenuation correction and whole-body PET. Feasibility was assessed by comparing the misalignment of the upper abdominal organs quantitatively by means of the craniocaudal, lateral, and anterior-posterior differences on coregistered PET/CT images. For image quality, the occurrence of CT artifacts and mismatching of rigid body points were evaluated qualitatively. RESULTS: Misalignment was significantly lower for protocol B in almost all organs and represented the best coregistration quality. Surprisingly, protocol A showed significantly better alignment than the multiphase CT scans during NormExp. Misalignment values between the multiphase protocols were not significantly different, with a trend toward lower values for protocol D. The best CT image quality, with a significantly lower occurrence of artifacts, was found for protocols B and D (NormExp). The levels of mismatching of rigid body points because of patient movement in between the transmission and emission scans were similar for all protocols. CONCLUSION: Multiphase CT protocols presented a technical disadvantage represented by suboptimal image coregistration compared with single-phase protocols. Nevertheless, multiphase protocols are technically feasible and should be considered for patients who will benefit from a contrast-enhanced multiphase CT examination for diagnosis.

Artifacts↗

PubMed2006

Performance test of an LSO-APD detector in a 7-T MRI scanner for simultaneous PET/MRI.

UNLABELLED: PET combined with CT has proven to be a valuable multimodality imaging device revealing both functional and anatomic information. Although PET/CT has become completely integrated into routine clinical application and also has been used in small-animal imaging, CT provides only limited soft-tissue contrast and, in preclinical studies, exposes the animal to a relatively high radiation dose. Unlike CT, MRI provides good soft-tissue contrast even without application of contrast agents and, furthermore, does not require ionizing radiation. METHODS: This project focused on combining a high-resolution PET scanner with a 7-T MRI system for animal research. Because classic PET detectors based on photomultiplier tubes cannot be used in high magnetic fields, we used a detector technology based on 10 x 10 lutetium oxyorthosilicate crystal arrays and 3 x 3 avalanche photodiode arrays. A ring of such PET detectors will ultimately be used as an insert for the 119-mm-diameter MRI bore. RESULTS: Initial measurements with 1 PET detector module in the 7-T field during application of MRI sequences were encouraging. Position profiles from the PET detectors and a first MR image of a mouse could be acquired simultaneously. CONCLUSION: Further work will concentrate on the construction of a full PET detector ring with compact, integrated electronics.

Animals↗

PubMed2005

Prevention of carotid artery restenosis after sirolimus-coated stent implantation in pigs.

BACKGROUND AND PURPOSE: To test the feasibility of self-expanding drug-coated nitinol stents for prevention of restenosis in an animal model. Stent implantation in the carotid artery (CA) has been shown to be feasible for treatment of CA stenosis. Even though the restenosis rate in CA is reported to be lower than in the coronary and peripheral arteries, problems may arise with increasing numbers of treated patients and lengthier follow-up. METHODS: After predilatation with 8-mm balloons, 8 Goettinger minipigs were randomly selected to receive a sirolimus-eluting self-expanding nitinol stent (7 mm/80 mm) as well as the same stent without sirolimus/polymer coating in the right or left CA. Aspirin was given starting 3 days before the intervention and administered for an additional 4 weeks. Clopidogrel was administered for 10 days. RESULTS: After 6 weeks, 2 subacute occlusions were observed in both groups. In the remaining vessels, the neointima was significantly reduced by sirolimus/polymer-coated stents (5.9+/-2.5 versus 0.7+/-1.0 mm2). CONCLUSIONS: Sirolimus self-expanding nitinol stents may be an effective tool in reducing neointimal formation in CA.

Alloys↗

PubMed2005

Prospective comparison of the impact on treatment decisions of whole-body magnetic resonance imaging and computed tomography in patients with metastatic malignant melanoma.

Patient management and treatment strategies for metastatic melanoma depend largely on the stage of metastatic disease. The aim of this study was to compare contrast-enhanced whole-body magnetic resonance imaging (wbMRI) and whole-body computed tomography (wbCT) to detect distant metastases for staging. A total of 43 patients (41 with completed wbCT and wbMRI examination) with known American Joint Committee on Cancer (AJCC) stage III-IV malignant melanoma were examined and 775 metastases were identified by both methods. Whole-body CT was able to detect 522 metastases, whereas wbMRI found 730 metastases. Whole-body CT identified 188 pulmonary metastases, compared with 143 metastases detected by wbMRI. In kidneys, adrenal glands and lymph nodes, respectively, wbCT and wbMRI detected the same number of lesions. Whole-body MRI detected more metastases than wbCT in liver (detection rate 122/199), spleen (26/54), subcutaneous tissue (39/61), muscle (4/11), bone marrow (23/132) and brain (15/25). Therapy was modified as a consequence of wbMRI findings in 10/41 (24%) patients. In conclusion, wbMRI detected clearly more malignant melanoma metastases in most organ systems with the exception of lung metastases. More accurate and complete staging by wbMRI has an impact on treatment strategy in about one-quarter of the patients.

Adolescent↗

PubMed2005

Interaction between grounding pads used for RF ablation therapy and magnetic resonance imaging.

OBJECTIVES: To characterize artifacts and imaging problems in the presence of conductive grounding pads for RF ablation therapy as well as potential heating problems due to induction of eddy currents in the pads. Strategies for avoidance of those problems are developed. MATERIALS AND METHODS: Underlying principles of interactions between grounding pads and MR imaging are reported. Influential parameters, e.g., orientation in relation to the magnetic field, shape of the grounding pad, sequence type (spin-echo versus gradient echo) and magnetic field strength (0.2 T, 1.5 T, 3 T) were varied in systematic phantom studies. Heating effects due to induced eddy currents were estimated theoretically and measured by infrared imaging in an adapted set-up. RESULTS: MR imaging artifacts are markedly dependent on the orientation and geometrical shape of the grounding pads. Visible signal extinction artifacts were more pronounced using spin-echo techniques than in gradient echo images and increased for higher field strengths. Suitable incisions in the grounding pad reduced eddy currents markedly and minimized image artifacts. Heating problems due to induced eddy currents by the RF transmitted for MR imaging were excluded by phantom measurements. CONCLUSIONS: Suitable positioning of the grounding pads and adaptation of their geometry provide clearly reduced artifacts in MR imaging.

Animals↗

PubMed2005

Atherosclerotic disease: whole-body cardiovascular imaging with MR system with 32 receiver channels and total-body surface coil technology--initial clinical results.

In this prospective study, the feasibility of a comprehensive cardiovascular imaging protocol with a dedicated whole-body 1.5-T magnetic resonance (MR) imager with 32 receiver channels in 34 patients with peripheral arterial occlusive disease was evaluated. Informed consent and institutional review board approval were obtained. Three-dimensional MR angiographic data sets were acquired with adapted injection protocol. Cardiac functional imaging and delayed-enhancement imaging were performed, as were fluid-attenuated inversion-recovery imaging of the brain and time-of-flight MR angiography of the intracranial blood vessels. Sensitivity and specificity for depiction of significant vascular stenosis (> 70%) were 96%, with conventional digital subtraction angiography as the standard. Substantial microangiopathic tissue alterations (n = 4) and/or cerebral infarction (n = 4) were diagnosed in seven patients. In seven patients, subendocardial or transmural delayed enhancement was detected in corresponding regions, indicating prior myocardial infarction. Previously unknown findings diagnosed with MR imaging required midterm follow-up or therapy in 24 patients, whereas change of therapy or immediate treatment was necessary in three. For patients suspected of having systemic atherosclerotic disease, comprehensive risk assessment is feasible within 30 minutes.

Adult↗

PubMed2005

Assessment of left ventricular myocardial function using 16-slice multidetector-row computed tomography: comparison with magnetic resonance imaging and echocardiography.

OBJECTIVE: To assess functional parameters using multidetector-row computed tomography (MDCT) and echocardiography and to compare the results with magnetic resonance imaging (MRI). MATERIALS AND METHODS: End-diastolic-volume (EDV), end-systolic-volume (ESV), stroke-volume (SV), ejection-fraction (EF), and myocardial mass (MM) were calculated based on CT data sets from 52 patients. Echocardiography was performed in 24 of the 52 patients. The results from MDCT and echocardiography were compared with MRI. RESULTS: A strong correlation between MDCT and MRI (r=0.66-0.90) was found for all parameters. Echocardiography revealed a low or moderate correlation (0.05-0.59). Compared to MRI the average differences with MDCT were for EDV 15.1 ml, ESV 10.6 ml, SV 4.5 ml, EF 1.8%, and MM 8.2 g, for EDV determined by echocardiography 36.2 ml, ESV 6.8 ml, and EF 13.9%. Bland-Altman analysis revealed acceptable limits of agreement between MRI and MDCT. CONCLUSIONS: MDCT enables reliable quantification of left ventricular function. Echocardiography was found to have only a moderate agreement of functional parameters with MRI.

Coronary Angiography↗

PubMed2005

Myocardial perfusion after angioplasty in patients suspected of having single-vessel coronary artery disease: improvement detected at rest-stress first-pass perfusion MR imaging--initial experience.

PURPOSE: To prospectively assess myocardial perfusion before and after successful intervention in patients suspected of having single-vessel coronary artery disease by using a steady-state free precession (SSFP) perfusion magnetic resonance (MR) imaging sequence. MATERIALS AND METHODS: Local ethics committee approval and informed consent were obtained. Rest-stress perfusion MR imaging studies were performed in 18 patients with coronary artery disease (12 men, six women; mean age, 58.6 years +/- 13.6 [standard deviation]; range, 30-79 years) at 1.5 T with a multisection saturation-recovery SSFP sequence and 0.025 mmol gadopentetate dimeglumine per kilogram of body weight. MR studies were performed before (n = 18), several days after (n = 18), and 8 months after (n = 10) coronary intervention. Nine patients underwent percutaneous transluminal coronary angioplasty (PTCA) alone, and nine patients underwent PTCA with stent placement. Myocardial perfusion reserve index (MPRI) was calculated by dividing results of myocardial perfusion at maximal vasodilation by results at rest. The standard for myocardial perfusion was technetium 99m tetrofosmin single photon emission computed tomography. Statistical significance was tested with univariate variance analysis and Student t tests. RESULTS: In the area of the stenosed vessel, MPRI was 1.04 +/- 0.24 before treatment and 2.18 +/- 0.57 several days afterward (P < .001). In remote areas, MPRI was 2.42 +/- 0.44. In the stent group, MPRI increased by 156%, from 0.99 +/- 0.20 before stent placement to 2.53 +/- 0.53 after (P < .001). Similarly, in the PTCA only group, MPRI increased by 72%, from 1.08 +/- 0.27 before PTCA to 1.87 +/- 0.39 after (P < .001). At follow-up in patients without recurring chest pain, MPRI was 2.14 +/- 0.37 in the area of the treated artery and 2.29 +/- 0.47 in remote areas (P = .06). CONCLUSION: The MPRI, derived from rest-stress examinations, can provide information on success of interventional procedures in stenosed coronary arteries.

Adult↗

PubMed2005

Reduced thrombogenicity of nitinol stents--in vitro evaluation of different surface modifications and coatings.

The material and the surface patterns of intravascular stents play a pivotal role in activating platelets and triggering adherence of inflammatory cells that consecutively leads to renarrowing caused by neointimal hyperplasia. To improve these features, besides mechanical and chemical modifications, ways of masking the stent by covering have been developed. In addition, polymer-coated stents are used as vehicle for local drug delivery. But as substances used for this application are described to possess an inflammatory potential, this aspect has to be evaluated. In the present study we compared different approaches to surface alterations applied to a nitinol stent design. Besides commonly used techniques like passivation and electropolishing, we evaluated coatings with heparin, aluminium and a polyurethane polymer regarding their thrombogenic and inflammatory characteristics. By weaving thin elastomer fibres a graft was generated. The previously described Chandler loop was used to simulate arterial flow conditions ex vivo using rotating PVC tubings filled with human blood. All stents received 120 min of blood contact. To determine thrombocyte activation and inflammatory reaction, the platelet count and levels of beta-TG, TAT and PMN-elastase were assessed. Scanning electron microscopy was used to visualize the reactions. Mechanical polishing and passivation did not improve the stent surface characteristics while sandblasting, electropolishing and aluminium covering decreased activation of the coagulation cascade. In terms of thrombogenicity, the heparin coating had no beneficial effect. The lowest thrombogenic potential was found in the Polyurethane-coated stent group. All stents showed similar levels of polymorph nuclear granulocyte elastase except for the membrane design. While mechanical and chemical modifications are able to reduce thrombogenicity, coating with this particular polyurethane polymer seems to be superior to these approaches regarding the parameters assessed in this experimental setting. The Chandler loop is a valuable tool to test polymeric coatings ex vivo since these modifications may reduce drug performance by inducing inflammatory reaction themselves.

Alloys↗

PubMed2005

Usefulness of noninvasive MSCT coronary angiography as first-line imaging technique in patients with chest pain: initial clinical experience.

PURPOSE: Comparative studies with invasive coronary angiography (ICA) indicated a good sensitivity and specificity in the noninvasive detection of coronary artery disease (CAD) using Multi-slice spiral computed tomography coronary angiography (MS-CTA). The aim was to investigate the usefulness of MS-CTA as first-line imaging technique in patients (pts) with known or suspected CAD and low to intermediate probability of a severe coronary lesion. We report on our initial clinical experience using MS-CTA without compelled ICA. MATERIAL AND METHODS: One hundred thirty six patients with chest pain underwent MS-CTA on an outpatient basis (age 60+/-10, suspicion of CAD: n=95, suspicion of restenosis: n=24, after CABG: n=17). Based on the MS-CTA results, a recommendation concerning further diagnostics and therapy was given to each pt. A telephone interview was performed after 455+/-166 days to evaluate the further clinical course. RESULTS: Per pt, 8.2+/-2.7 coronary segments could be evaluated. Based on the MSCT results, the presence of flow-limiting stenoses was excluded in n=77 (57%) pts (group I). An additional ICA was recommended in n=59 (43%) pts (group II). An ICA had been performed in meantime in 27/136 (20%) pts, and could be avoided in the majority of pts. Nevertheless, 58/136 (42%) pts reported on improved clinical symptoms and 42/136 (31%) pts of improved quality of life. CONCLUSIONS: MS-CTA was found to be useful to evaluate the need and to reduce the total number of ICA in pts with unclear chest pain. It appears to be the first noninvasive modality, which might be used on a clinical routine basis in selected groups of pts.

Aged↗

PubMed2005

Visualization of pulmonary vein stenosis after radio frequency ablation using multi-slice computed tomography: initial clinical experience in 33 patients.

PURPOSE: Radio frequency ablation (RFA) of the pulmonary veins (PV) is an established technique for treatment of atrial fibrillation (AF). However, stenoses within the treated areas are well known complications. Thus, a reliable non-invasive diagnosis of PV stenosis would be an important step forward in the care of these patients (pts). Aim of the present study was the diagnostic accuracy of new multi-slice detected computed tomography (MSCT) in visualization of PV and in detecting PV stenosis. MATERIAL AND METHODS: A total of 33 pts (17 male, 16 female, mean age 57+/-10.2 years [40-71]) were included. Retrospectively ECG-gated CT angiography (CTA) was performed within 1 day to a maximum of 380 days after RFA with a MSCT scanner. Interpretation of the scan was performed on conventional contrast enhanced axial slices and on 3D volume rendering images (maximum intensity projection: MIP, multi-planar reconstruction: MPR). Lesion severity was determined on a semi-quantitative scale (mild: <20%, intermediate: 20-50%, severe >50%) and compared to conventional angiography which had been performed at the beginning and at the end of RFA. RESULTS: MSCTA was applied without any complications, and all treated pulmonary veins (n=73) could be visualized. Diagnostic image quality was obtained in all examinations. A significant stenosis was detected by conventional angiography in 26/73 (36%) PV (2/73 (3%) severe, 14/73 (19%) intermediate, 10/73 (14%) mild). Using MSCTA, only 13 stenosis in 73 treated PV could be visualized (1/73 (1%) severe, 6/73 (8%) intermediate, 6/73 (8%) mild). CONCLUSIONS: Multi-slice-detector CT is able to visualize PV and to detect PV stenoses. However, stenosis severity seems to be underestimated and not all lesions could be accurately detected. Larger studies have to be performed to further assess the diagnostic accuracy and clinical reliability of this new non-invasive method and to focus on the incidence of PV stenosis following RFA especially in long-time follow up.

Adult↗

PubMed2005

Liver fat and insulin resistance are independently associated with the -514C>T polymorphism of the hepatic lipase gene.

CONTEXT: Liver fat predicts insulin resistance in humans. So far, there is not much information on genetic determinants of liver fat. Hepatic lipase is a liver-specific enzyme that regulates lipid metabolism. OBJECTIVE: First, our object was to investigate whether the functional -514C>T polymorphism of the hepatic lipase gene is associated with liver fat content and with insulin sensitivity. Second, because this polymorphism displays gene-nutrient interactions, we assessed gene-gene interactions with the Pro12Ala polymorphism of the peroxisome proliferator-activated receptor-gamma(2) on liver fat content and insulin sensitivity. DESIGN AND METHODS: Cross-sectional data from a total of 1070 nondiabetic subjects were analyzed. Insulin sensitivity was estimated from a 75-g oral glucose tolerance test. A subgroup of 115 subjects underwent measurements of liver fat. RESULTS: The -514C>T polymorphism of the hepatic lipase gene was associated with higher liver fat content (P = 0.005) and lower insulin sensitivity (P = 0.02), both after adjustment for age, gender, and percentage of body fat. This was independent of serum adiponectin concentrations (P = 0.01 and 0.03). However, there was an interaction of the -514C>T polymorphism with the Pro12Ala variant on liver fat (P = 0.09) and insulin sensitivity (P = 0.01). Subjects carrying the -514C>T polymorphism had higher liver fat content and were insulin resistant only before the background of the Pro/Pro genotype of the Pro12Ala polymorphism. CONCLUSIONS: The -514C>T polymorphism of the hepatic lipase gene is associated with higher liver fat content and lower whole-body insulin sensitivity. However, these effects are modulated by the common Pro12Ala polymorphism in peroxisome proliferator-activated receptor-gamma(2). These findings may be relevant for intervention strategies to prevent increase in liver fat content and insulin resistance.

Adult↗

PubMed2005

Diagnosis of vascular rings and slings using an interleaved 3D double-slab FISP MR angiography technique.

BACKGROUND: Congenital upper airway obstruction and dysphagia may be caused by vascular rings and slings. Often, invasive and radiation-dependent diagnostic procedures are needed to clarify the diagnosis. OBJECTIVE: To evaluate the diagnostic utility of high-resolution, free-breathing three-dimensional double-slab fast imaging with steady precession magnetic resonance angiography (3D FISP MRA) in infants and children with respiratory upper airway obstruction and/or dysphagia for detection or exclusion of vascular rings and slings. MATERIALS AND METHODS: Eleven patients (median age 1.3 years; range 5.1 months to 15.8 years) were investigated prospectively with 3D FISP MRA and spin-echo techniques. Additional diagnostic data were available from surgery (n=7), cardiac catheterization (n=5), CT (n=2), barium swallow (n=3) and bronchoscopy/oesophagoscopy (n=4). RESULTS: In one case, diagnosis was missed with low-resolution spin-echo sequences, but high-resolution 3D FISP MRA revealed a double aortic arch. 3D FISP MRA accurately found (n=8) or excluded (n=3) vascular rings or slings in all patients. Using a five-level grading system for 3D FISP MRA image quality (1=non-diagnostic; 5=excellent), the mean grade was 4.3+/-0.7 with no significant grade difference between two independent observers (P=0.81). CONCLUSIONS: High-resolution 3D FISP MRA accurately defined or excluded vascular rings and slings in patients with respiratory symptoms and/or dysphagia. This technique may provide a non-invasive, radiation-free alternative without contrast agents for diagnosis of vascular rings and slings in free-breathing infants and children.

Adolescent↗

PubMed2005

Diagnostic accuracy of noninvasive coronary imaging using 16-detector slice spiral computed tomography with 188 ms temporal resolution.

OBJECTIVES: The aim of our study was to evaluate the diagnostic accuracy of 16-multi-detector spiral computed tomography (MDCT) with 188 ms temporal resolution. BACKGROUND: Because of rapid technical innovations, MDCT coronary imaging has significantly improved in the last five years. Recent results indicate a high diagnostic accuracy, especially in patients with clinical suspicion of coronary artery disease (CAD). METHODS: A total of 72 consecutive patients (30 women, 42 men, age 64 +/- 10 years) scheduled for invasive coronary angiography (ICA) because of suspected CAD were additionally studied by MDCT (Sensation 16 Speed 4D, Siemens, Forchheim, Germany). Thirty-seven of 72 patients (51%) received an additional beta-blockade before MDCT because of heart rates >65 beats/min. The MDCT scans were analyzed regarding the presence of coronary artery lesions. Results were compared with ICA. RESULTS: All 72 scans showed diagnostic image quality (heart rate: 64.1 +/- 9.2 beats/min, calcium mass: 86 +/- 156 mg). Thirteen coronary segments were evaluated in each patient. Sixty-two of 936 (6.6%) segments showed a nondiagnostic image quality. All segments were included in the analysis. A total of 117 relevant lesions (diameter stenosis >50%) were detected using ICA, and 96 of 117 (82%) were detected by MDCT. Sensitivity, specificity, and positive and negative predictive values for the whole study group were as follows: 82%, 98%, 87%, and 97%, respectively. The correct clinical diagnosis of presence or absence of significant CAD was obtained in 65 of 72 (90%) patients. All stenoses were detected by MDCT in 52 of 72 (72%) patients. CONCLUSIONS: Our results indicate a high diagnostic accuracy of 16-slice MDCT with improved temporal resolution.

Adult↗