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Claus D Claussen

Publications and source records attributed to Claus D Claussen.

At least 37 records · Page 2Linked to original sources
PubMed2006

MRI-guided biopsy of the prostate increases diagnostic performance in men with elevated or increasing PSA levels after previous negative TRUS biopsies.

OBJECTIVES: Repeatedly negative prostate biopsies in individuals with elevated prostate specific antigen (PSA) levels can be frustrating for both the patient and the urologist. This study was performed to investigate if magnetic resonance imaging (MRI)-guided transrectal biopsy increases diagnostic performance in individuals with elevated or increasing PSA levels after previous negative conventional transrectal ultrasound (TRUS)-guided biopsies. METHODS: 27 consecutive men with a PSA >4 ng/ml and/or suspicious finding on digital rectal examination, suspicious MRI findings, and at least one prior negative prostate biopsy were included. Median age was 66 years (mean, 64.5+/-6.8); median PSA was 10.2 ng/ml (mean, 11.3+/-5.5). MRI-guided biopsy was performed with a closed unit at 1.5 Tesla, an MRI-compatible biopsy device, a needle guide, and a titanium double-shoot biopsy gun. RESULTS: Median prostate volume was 37.4 cm3 (mean, 48.4+/-31.5); median volume of tumor suspicious areas on T2w MR images was 0.83 cm3 (mean, 0.99+/-0.78). The mean number of obtained cores per patient was 5.22+/-1.45 (median, 5; range, 2-8). Prostate cancer was detected in 55.5% (15 of 27) of the men. MRI-guided biopsy could be performed without complications in all cases. CONCLUSION: According to our knowledge, this is the largest cohort of consecutive men to be examined by MRI-guided transrectal biopsy of the prostate in this setting. The method is safe, can be useful to select suspicious areas in the prostate, and has the potential to improve cancer detection rate in men with previous negative TRUS-biopsies.

Biopsy↗
PubMed2006

Imaging of aortopulmonary collateral arteries with high-resolution multidetector CT.

BACKGROUND: Precise visualization of the pulmonary vasculature is mandatory for adequate treatment of patients with pulmonary atresia and ventricular septal defect (PA-VSD). Aortopulmonary collateral arteries (APCs) can be visualized by selective injections of contrast agent in the catheterization laboratory. OBJECTIVE: To evaluate multidetector CT (MDCT) and different image postprocessing methods for analysis of complex pulmonary blood supply in patients with PA-VSD. MATERIALS AND METHODS: Eight patients (6 weeks to 27.8 years of age) with PA-VSD and APCs underwent MDCT and cardiac catheterization. Using multiplanar reformatting, volume rendering and semiautomatic segmentation algorithms, the aorta, pulmonary arteries and APCs were displayed. MDCT and cardiac catheterization were analyzed by two independent observers. RESULTS: MDCT accurately imaged central pulmonary arteries (n=8), aortopulmonary shunts (n=2), right ventricular to pulmonary artery conduits (n=2) and origin, course and intrapulmonary connections of APCs (n=25), compared to X-ray angiography. A high correlation was found between the MDCT vessel diameter measurements by two independent observers (n=70, r=0.96, P<0.01) and between MDCT and angiographic vessel diameter measurements (n=68, r=0.96, P<0.01). CONCLUSIONS: Using three-dimensional imaging software, a complex pulmonary blood supply can be non-invasively and accurately imaged with high-resolution MDCT. This technique may help to reduce the number of cardiac catheterizations or guide interventional or surgical therapy.

Adolescent↗
PubMed2006

Superficial femoral artery: current treatment options.

Treatment of the superficial femoral artery (SFA) has been among the least effective of all endovascular procedures in terms of long-term patency. The relatively small vessel lumen, in conjunction with a high plaque burden, slow flow, and a high frequency of primary occlusions, contributes to a considerable rate of acute technical failures. Because of these technical limitations a much effort has been made during the past years. This manuscript should summarize the hopes and limitations of different approaches such as brachytherapy, cutting balloons, stents and stent grafts, drug-eluting stents, and drug-coated balloons.

Angioplasty, Balloon↗
PubMed2006

Morphological, contrast-enhanced and spin labeling perfusion imaging for monitoring of relapse after RF ablation of renal cell carcinomas.

MR perfusion imaging was applied for the assessment of completeness in the destruction of renal cell carcinomas by RF ablation (RFA) in a pilot study. An arterial spin labeling (ASL) approach was compared to conventional contrast-enhanced T1-weighted (CE-T1w) imaging. Ten patients suffering from renal cell carcinoma were treated by RFA. For the assessment of the extent of coagulation and for the detection of residual tumor, T1-weighted gradient-echo imaging, T2-weighted spin echo imaging and two different perfusion imaging techniques were performed before, 1 day and 6 weeks after RFA at 1.5 T. Perfusion imaging comprised CE-T1 weighted and FAIR-TrueFISP ASL imaging. Perfusion images recorded in the acute stage after RFA showed higher compliance to the definitive ablation volume reached after 6 weeks than T2-weighted images, which underestimated the true necrosis size. In the detection of residual tumor tissue, both modalities complimented each other. The exclusion of residual tumor tissue could more reliably be performed using perfusion-imaging methods. Both perfusion-imaging modalities showed sufficient imaging quality for post-interventional monitoring. Perfusion imaging provides a higher predictability of the completeness of tumor ablation and extent of coagulation than T2-weighted imaging alone. Since the results of the FAIR-TrueFISP sequence are promising, the administration of potentially nephrotoxic contrast media may be avoided in the respective patient cohort.

Aged↗
PubMed2006

Perfusion MR imaging with FAIR true FISP spin labeling in patients with and without renal artery stenosis: initial experience.

The purpose of this study was to prospectively evaluate an arterial spin-labeling technique, flow-sensitive alternating inversion-recovery (FAIR) true fast imaging with steady-state precession (FISP), for noninvasive quantification of renal perfusion in patients without a history of renal artery stenosis (RAS) and in patients with proved RAS. The study was approved by the local ethics committee, and all participants provided written informed consent. Six patients with hypertension but no history of renal artery disease and 12 patients with RAS underwent FAIR true FISP magnetic resonance (MR) imaging in a whole-body 1.5-T unit. RAS grade and scintigraphic perfusion data served as the reference standards. On the FAIR true FISP perfusion images, severe RAS (>70% luminal narrowing) could be clearly distinguished from no or mild RAS and moderate RAS (< or =70% luminal narrowing) (P < .005). Significant correlations between FAIR perfusion data and stenosis grade (r = -0.76) and between FAIR and single photon emission computed tomographic perfusion values (r = 0.83) were observed. FAIR true FISP was found to be suitable for quantitative perfusion imaging of the kidneys in patients with RAS.

Aged↗
PubMed2006

New imaging techniques of fat, muscle and liver within the context of determining insulin sensitivity.

Body fat distribution and ectopic fat deposition are important determinants of insulin sensitivity. Fat deposition in muscle and the liver, in particular, has been found to impair insulin signalling in these insulin-sensitive tissues. Thus, exact quantification of fat content may help to distinguish between different sites of insulin resistance. Increased fat deposition in the visceral compartment compared with the subcutaneous depot also represents an important factor leading to insulin resistance. Recent data clearly showed that visceral fat is a strong determinant of liver fat content. Exact quantification of fat distribution by magnetic resonance imaging and magnetic resonance spectroscopy may help to define distinct 'fat-distribution phenotypes'. This may allow a search for new candidate genes for type 2 diabetes mellitus and identify, at an early stage, individuals at risk for decline in insulin sensitivity.

Body Fat Distribution↗
PubMed2006

Multipolar radiofrequency ablation with internally cooled electrodes: experimental study in ex vivo bovine liver with mathematic modeling.

PURPOSE: To evaluate the size and geometry of thermally induced coagulation by using multipolar radiofrequency (RF) ablation and to determine a mathematic model to predict coagulation volume. MATERIALS AND METHODS: Multipolar RF ablations (n = 80) were performed in ex vivo bovine livers by using three internally cooled bipolar applicators with two electrodes on the same shaft. Applicators were placed in a triangular array (spacing, 2-5 cm) and were activated in multipolar mode (power output, 75-225 W). The size and geometry of the coagulation zone, together with ablation time, were assessed. Mathematic functions were fitted, and the goodness of fit was assessed by using r(2). RESULTS: Coagulation volume, short-axis diameter, and ablation time were dependent on power output and applicator distance. The maximum zone of coagulation (volume, 324 cm(3); short-axis diameter, 8.4 cm; ablation time, 193 min) was induced with a power output of 75 W at an applicator distance of 5 cm. Coagulation volume and ablation time decreased as power output increased. Power outputs of 100-125 W at applicator distances of 2-4 cm led to a reasonable compromise between coagulation volume and ablation time. At 2 cm (100 W), coagulation volume, short-axis diameter, and ablation time were 66 cm(3), 4.5 cm, and 19 min, respectively; at 3 cm (100 W), 90 cm(3), 5.2 cm, and 22 min, respectively; at 4 cm (100 W), 132 cm(3), 6.1 cm, and 27 min, respectively; at 2 cm (125 W), 56 cm(3), 4.2 cm, and 9 min, respectively; at 3 cm (125 W), 73 cm(3), 4.9 cm, and 12 min, respectively; and at 4 cm (125 W), 103 cm(3), 5.5 cm, and 16 min, respectively. At applicator distances of 4 cm (>125 W) and 5 cm (>100 W), the zones of coagulation were not confluent. Coagulation volume (r(2) = 0.80) and RF ablation time (r(2) = 0.93) were determined by using the mathematic model. CONCLUSION: Multipolar RF ablation with three bipolar applicators may produce large volumes of confluent coagulation ex vivo. A compromise is necessary between prolonged RF ablations at lower power outputs, which produce larger volumes of coagulation, and faster RF ablations at higher power outputs, which produce smaller volumes of coagulation.

Animals↗
PubMed2006

Non-invasive evaluation of coronary artery bypass grafts using 16-row multi-slice computed tomography with 188 ms temporal resolution.

BACKGROUND: Cardiac multi-slice computed tomography (MSCT) scanners permit visualization of the coronary arteries and coronary artery bypass grafts. The latest MSCT generation with true 16-detector slices (Sensation 16 Speed 4 D, Siemens, Forchheim, Germany) provides improved temporal and spatial resolution, as well as significantly reduced scan time. To assess, whether this technical improvement has also an impact on image quality and accuracy of MSCT diagnosis in patients with previous coronary artery bypass graft (CABG) surgery the following study was conducted. METHODS AND MATERIAL: Thirteen consecutive patients (pts) (10 male, 3 female, mean age 62 +/- 6.4 [55-73] years, heart rate 68 +/- 11 [52-88] bpm) and a total number of 43 coronary bypass grafts (11 arterial, 32 venous grafts) were examined by MSCT (gantry rotation time 375 ms). In addition to the analysis of coronary bypass grafts, 13 coronary segments (sgts) were evaluated in each patient (n = 169 sgts). MSCT results were compared with coronary angiography. RESULTS: Forty-one of 43 bypass grafts (95%) were analyzable by MSCT. In conventional angiography 16 of 43 (37%) grafts were occluded. Sixteen of them were correctly diagnosed by MSCT (sensitivity 100%). One graft showed a 50% anastomosis stenosis which was also detected. Twenty-five of 27 grafts without severe lesion showed no significant stenosis in MSCT (specificity 93%, positive predictive value (PPV) 89%, negative predictive value (NPV) 100%). Ninety of 108 (83%) high-grade stenosis (>70%) of the native coronary vessels were correctly detected (sensitivity 83%, PPV 78%). From the 61 sgts without high grade stenosis 36 were correctly classified (specificity 59%, NPV 67%). If sgts number 8, 9 and 10, which are normally not target for revascularization, are excluded sensitivity rises to 89%, specificity to 71%, PPV to 87% and NPV to 75%. The correct clinical diagnosis (absence or presence of a high grade stenosis of at least one bypass graft) was achieved in all patients. CONCLUSIONS: True 16-slice MSCT with faster gantry rotation time allows detection of lesions in coronary artery bypass grafts with high sensitivity and specificity. The evaluation of native vessels in pts with known CAD remains a diagnostic challenge. However, the correct clinical diagnosis was achieved in all pts. MSCT is a non-invasive tool to assess coronary artery bypass grafts.

Aged↗
PubMed2006

MRI-compatible incubation chamber for cell culture experiments.

PURPOSE: To develop an incubation chamber that is compatible with MRI, while avoiding sources of error due to the experimental setup. MATERIALS AND METHODS: Two identical and gas-tight chambers were constructed of Plexiglas. The temperature and the CO(2) concentration were adjustable. Temperature variations within and between both chambers were measured. The pH values of the cell culture media were measured under different environmental settings. For each environment a colony formation test was carried out. The homogeneity of the magnetic field inside the chambers was estimated by phantom tests. RESULTS: The temperature variations within the chambers were <0.3 degrees C, and the variation between the chambers was on average <0.05 degrees C. After eight hours the pH values of the cell culture media were 7.47 and 7.48 in the reference and measurement chambers, respectively; 7.41 in the CO(2) incubator; and 8.73 in ambient air. In colony formation tests the survival fraction in the Plexiglas chamber was comparable to that in the CO(2) incubator. No distortions of the magnetic field from the incubation chamber were observed. CONCLUSION: The incubation system presented can provide the conditions of a CO(2) incubator without alteration of the magnetic flux density.

Carbon Dioxide↗
PubMed2006

Whole-body magnetization transfer contrast imaging.

PURPOSE: To demonstrate the feasibility of whole-body magnetization transfer (MT) contrast imaging. MATERIALS AND METHODS: Whole-body MT imaging was performed on eight healthy volunteers and five patients (mean age=40.5+/-17.8 years) with diagnoses of dermatomyositis (N=1), B-symptoms with suspicion of paraneoplastic disease (N=1), metastatic malignant melanoma (N=1), and multiple sclerosis (MS) (N=2). Measurements were carried out on a 1.5-Tesla whole-body MR scanner capable of parallel signal reception. A three-dimensional (3D) gradient-echo sequence (TR=17 msec, TE=4.8 msec, flip angle=10 degrees) was applied in combination with a Gaussian off-resonance MT preparation pulse acting at an off-resonance of 1.500 Hz with a 500 degrees effective flip angle. Whole-body images were constructed from five different body regions. RESULTS: In all subjects, whole-body MT contrast images were obtained within less than 20 minutes of measuring time. The images showed sufficient diagnostic image quality to assess the patients' pathologies. The MT ratios (MTRs, in percent units) for the volunteers were as follows: white matter (WM) 51.1+/-1.0, gray matter (GM) 42.2+/-1.3, skeletal muscle (mean value of four muscle groups) 50.3+/-2.1, liver 39.4+/-3.2, spleen 31.8+/-2.6, renal cortex 30.4+/-1.9, and renal medulla 25.6+/-1.3. The MTRs for the pathologies were as follows: skeletal muscle in dermatomyositis approximately 30, metastases in malignant melanoma 30.7-36.0, uterus myoma 49.3, and MS lesions 30-40. CONCLUSION: Our preliminary data indicate that MT contrast in whole-body MRI is feasible, and may be useful for rapid whole-body assessment of diseases that exhibit high contrast in MT imaging, such as MS and muscular disorders.

Adult↗
PubMed2006

Hepatic lipid accumulation in healthy subjects: a comparative study using spectral fat-selective MRI and volume-localized 1H-MR spectroscopy.

Fat-selective MRI was applied to assess the amount and spatial distribution of hepatic lipids (HL) in healthy subjects. The results were compared with those obtained by localized 1H-MR spectroscopy (MRS). Ninety subjects (23-63 years old) underwent single-slice fat-selective MRI with spatial-spectral excitation and volume-localized spectroscopy at 1.5 T. HLs were analyzed in ventral and dorsal regions of interest (ROIs) of the liver in fat-selective images. Spectra were evaluated using the integral signal of methylene and methyl signals. The fat-selective images showed smooth and homogeneous distribution of HL over the entire cross section of the liver. There was, however, a marked interindividual variability in the amount of HL. MRS revealed a lipid signal fraction between 0.5% and 39.3%. The fat content in the ROIs in images correlated well with the spectroscopic results (r >or= 0.95). Both techniques provide sufficient sensitivity for a reliable and quantitative assessment of liver steatosis in subjects without liver disease. 1H-MRS has a higher sensitivity compared to MRI, especially for small amounts of HL, which may be of interest for metabolic interventions. Fat-selective images provide more spatial information about fat distribution, which makes this technique suitable for clinical imaging of patients with liver disease.

Adult↗
PubMed2006

Quantitative lung perfusion mapping at 0.2 T using FAIR True-FISP MRI.

Perfusion measurements in lung tissue using arterial spin labeling (ASL) techniques are hampered by strong microscopic field gradients induced by susceptibility differences between the alveolar air and the lung parenchyma. A true fast imaging with steady precession (True-FISP) sequence was adapted for applications in flow-sensitive alternating inversion recovery (FAIR) lung perfusion imaging at 0.2 Tesla and 1.5 Tesla. Conditions of microscopic static field distribution were assessed in four healthy volunteers at both field strengths using multiecho gradient-echo sequences. The full width at half maximum (FWHM) values of the frequency distribution for 180-277 Hz at 1.5 Tesla were more than threefold higher compared to 39-109 Hz at 0.2 Tesla. The influence of microscopic field inhomogeneities on the True-FISP signal yield was simulated numerically. Conditions allowed for the development of a FAIR True-FISP sequence for lung perfusion measurement at 0.2 Tesla, whereas at 1.5 Tesla microscopic field inhomogeneities appeared too distinct. Perfusion measurements of lung tissue were performed on eight healthy volunteers and two patients at 0.2 Tesla using the optimized FAIR True-FISP sequence. The average perfusion rates in peripheral lung regions in transverse, sagittal, and coronal slices of the left/right lung were 418/400, 398/416, and 370/368 ml/100 g/min, respectively. This work suggests that FAIR True-FISP sequences can be considered appropriate for noninvasive lung perfusion examinations at low field strength.

Adolescent↗
PubMed2006

Quantitative ASL muscle perfusion imaging using a FAIR-TrueFISP technique at 3.0 T.

The feasibility of muscle perfusion imaging with diagnostic image quality was demonstrated using the FAIR-TrueFISP arterial spin labeling technique on a clinical 3.0 T whole-body scanner. In eight healthy volunteers (24 to 42 years old), quantitative perfusion maps of the forearm musculature were acquired before and after intense exercise. All measurements were carried out in a 3.0 T whole-body MR unit in combination with an eight-channel head coil. Pulsed arterial spin labeling and data recording were performed with an adapted FAIR-TrueFISP technique and quantitative perfusion maps were calculated on a pixel-by-pixel basis by means of the extended Bloch equations. Perfusion images with an in-plane resolution of 1 mm showed no significant distortions or blurring. Perfusion-time curves could be recorded with a temporal resolution of 6.4 s. Maximum perfusion in the musculature was found approximately 2 min after exercise, reaching values of up to 220 mL/min per 100 g of tissue with good delineation between the active muscles and the musculature not involved in the exercise. In conclusion, the TrueFISP pulsed arterial spin labeling technique allows patient-friendly assessment of muscular perfusion in a clinical whole-body scanner.

Adult↗
PubMed2006

Early effects of rhenium-188 treatment on proliferation, migration, and matrix synthesis of cultured human aortic smooth muscle cells.

BACKGROUND AND PURPOSE: Due to its properties rhenium-188 (188Re) seems to be a promising radionuclide for stent coating to reduce restenosis following percutaneous transluminal angioplasty (PTA). In order to characterize the early effects of local 188Re treatment, human aortic smooth muscle cells (HaSMCs) were incubated with different doses of 188Re. MATERIAL AND METHODS: 2 days after plating, HaSMCs were treated for a period of 5 days with 188Re. The total radiation doses applied were 1 Gy, 4 Gy, 8 Gy, 16 Gy, and 32 Gy. On days 1, 3, 5, and 7 (i.e., 2 days after the end of 188Re incubation), cell growth, clonogenic activity, cell migration, cell-cycle distribution, as well as matrix synthesis were evaluated. RESULTS: From the 1st day on, a dose-dependent growth inhibition was observed. Cumulative doses of > or = 8 Gy completely inhibited colony formation. The results of the migration tests were contradictory; on day 3 the migratory activity of all treated cells was increased compared to the controls, on day 5 it was reduced. Cumulative radiation doses of > or = 8 Gy resulted in an increased fraction of cells in G2/M-phase. The synthesis of the extracellular matrix protein tenascin was not affected by the treatment. CONCLUSION: Incubating human smooth muscle cells with 188Re for a period of 5 days (i.e., seven half-lives) results in an effective inhibition of muscle cell proliferation and colony formation. Partially, this is due to a radiation-induced G2/M-phase block. Cell migration and matrix synthesis were not effectively affected in the presented in vitro system.

Aorta↗
PubMed2006

Highly resolved free-breathing magnetic resonance cholangiopancreatography in the diagnostic workup of pancreaticobiliary diseases in infants and young children--initial experiences.

PURPOSE: A new generation of magnetic resonance imaging scanner offers a 3-dimensional magnetic resonance cholangiopancreatography (MRCP) with very high spatial resolution using a non-breath-hold technique with prospective navigator gating. The study aimed to investigate the new technology of the MRCP in infants with suspected pancreaticobiliary diseases. METHODS: Seven patients (4 girls, 3 boys; mean age, 2.8 years; range, 3 months to 5.6 years) were examined. All patients underwent magnetic resonance imaging examination using a 1.5-T whole-body scanner (Magnetom Avanto, Siemens Medical, Erlangen, Germany). For MRCP, a heavily T2-weighted (time to echo, 678 ms) 3-dimensional turbo spin echo in coronal plane was performed with the voxel size of 1 x 1 x 1.5 mm. To enable non-breath-holding imaging, a diaphragm navigator sequence was simultaneously carried out. The MRCP findings were compared prospectively with the endoscopic retrograde cholangiopancreatography and/or with the surgical findings in 6 of 7 cases. In 1 patient, the follow-up was considered reference standard. RESULTS: The high spatial resolution of the images without breathing artifacts allowed an excellent demonstration of all relevant pancreaticobiliary ducts and of the pathologic findings. All patients (n = 4) with choledocholithiasis were identified through MRCP. The finding of a high pancreaticobiliary junction (n = 3) was confirmed by endoscopic retrograde cholangiopancreatography in all cases. The length of the common channel ranged from 16 to 24 mm. In 1 patient, the long common channel was associated with a choledochal cyst. In a 1.7-year-old boy with recurrent abdominal pain and mild pancreatitis, the rare case of a gastric duplication with connection to the main pancreatic duct was diagnosed. A regular gastric wall with normal mucosa and parts of the duodenal wall with a circular layer of muscle (pylorus-like) were found in histology after surgical resection of the mass. CONCLUSION: The newly developed technique may be a reliable tool in the workup of pancreaticobiliary diseases in infants.

Biliary Tract↗
PubMed2006

Comparison of Gadolinium-BOPTA and Ferucarbotran-enhanced three-dimensional T1-weighted dynamic liver magnetic resonance imaging in the same patient.

OBJECTIVES: We sought to compare signal changes using Ferucarbotran and gadobenate dimeglumine (Gd-BOPTA) in dynamic 3D T1-weighted (T1w) GRE imaging of the liver. MATERIAL AND METHODS: Thirty patients were prospectively included in the study. All patients underwent 2 high-field magnetic resonance (MR) examinations: first with Gd-BOPTA (Gd) and then after a mean interval of 4 days with ferucarbotran (Feru). Dynamic MRI was obtained with a 3D T1w GRE sequence (TR 6.33, TE 2.31, flip angle 20 degrees ). Contrast enhanced scans were assessed before intravenous injection of the contrast agent (precontrast), and postcontrast during the arterial phase (30 seconds), portal venous phase (60 seconds), and equilibrium phase (120 seconds). The signal intensities (SIs) of liver, spleen, aorta, and portal vein were defined by region of interest measurements. Signal intensity changes (SICs) and percentage signal intensity change (PSIC) were calculated using the formulas SIC=(SI pre - SI post)/SI pre and PSIC=SIC x 100%. RESULTS: Positive signal enhancement was observed after intravenous injection of Feru during all dynamic measurements, whereas the mean SI values were lower compared with Gd. During the portal venous phase the mean SI of Gd was up to a factor of 2.1 higher (portal vein). The widest difference of SIC was observed during the equilibrium phase for liver parenchyma (Gd, 1.03; Feru, 0.24). The dynamic signal courses were similar for liver, portal vein and aorta. Different signal courses were obtained for the spleen. CONCLUSIONS: Feru-enhanced T1w dynamic images demonstrated significant signal increases for liver, vessels, and spleen but overall lower signal intensities than Gd-BOPTA. The dynamic signal courses of ferucarbotran were similar to that of Gd-BOPTA during ll perfusion phases except in the spleen. Thus, it may be possible to detect typical enhancement pattern of focal liver lesions with Feru-enhanced dynamic T1w MRI.

Adult↗
PubMed2006

High-resolution magnetic resonance angiography of the renal arteries using parallel imaging acquisition techniques at 3.0 T: initial experience.

OBJECTIVE: The purpose of this prospective study was to investigate the feasibility of high-resolution magnetic resonance angiography (MRA) of the kidneys at 3.0 T using parallel data acquisition. MATERIAL AND METHODS: Contrast-enhanced MRA of the renal arteries (RA) was performed in 12 volunteers and 12 consecutive patients (mean age 47.1 +/- 16.3 years) on a 3.0 T MR scanner. For CEMRA, a high-resolution 3-dimensional GRE FLASH sequence was implemented. Images were assessed subjectively on a 0 to 5 scoring scale by 2 reviewers. Quantitative evaluation was done by measuring the contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR). RESULTS: Diagnostic image quality was acquired in all individuals. In total, 62 RA were found, consisting of 48 main and 14 accessory RA. Overall visibility score for main RA was 4.82 +/- 0.38. RA were identified up to the third-order branches in 88%. In 3 of 12 patients, a hemodynamic relevant stenosis was found and proven by conventional angiogram. CONCLUSION: CEMRA at 3.0 T is advantageous in terms of better SNR and T1 weighting; therefore, measurement time can be reduced and spatial resolution can be increased without corruption of signal yield. Consequently, high-field MRA may be preferred for the evaluation of renal vascular anatomy in potential kidney donors or for the detection of renal artery stenosis.

Adult↗