Stefan Haneder

Publications of Stefan Haneder

• Impact of Iso- and Low-Osmolar Iodinated Contrast Agents on BOLD and Diffusion MRI in Swine Kidneys.

  Authors: Stefan Haneder, Jill Augustin, Gregor Jost, Hubertus Pietsch, Philipp Lengsfeld, Bernhard K Krämer, Stefan O Schoenberg, Mathias Meyer, Ulrike I Attenberger, Henrik Jakob Michaely

  Investigative radiology. 05/2012; 47(5):299-305.

  : To assess whether functional MR imaging using blood-oxygenation level-dependent (BOLD) imaging and diffusion-weighted imaging demonstrate changes in renal oxygenation and apparent diffusion: To assess whether functional MR imaging using blood-oxygenation level-dependent (BOLD) imaging and diffusion-weighted imaging demonstrate changes in renal oxygenation and apparent diffusion coefficient (ADC) in a pig model. : After administration of either 1-g iodine/kg body weight low-osmolar iopromide or iso-osmolar iodixanol, 8 mini pigs underwent a series of repeated BOLD measurements (TR/TE 106/5.9-48.7 ms, slice thickness 4 mm) and diffusion-weighted imaging measurements (TR/TE 3900/79 ms, slice thickness 4 mm) for 1 hour at 1.5 T. In this intraindividual cross over study, the second contrast agent injection with the other iodinated contrast agent was performed at least 24 hours after the initial contrast agent injection. BOLD-based R2* values as indirect measures of the renal oxygenation were determined for the cortex, the inner medulla, and the outer medulla. ADC values were measured for the cortex and the whole kidney. : For both contrast agents, a drop in R2* was found in the cortex, which normalized after 55 minutes. In the outer medulla and particularly in the inner medulla, a decreased initial drop of R2* was encountered with both contrast agents, with a slow increase toward the baseline R2*. In the inner medulla, elevated R2* values were found with the iso-osmolar contrast agent only. The ADC revealed an initial increase, which slowly decayed over the measurement period. This finding was more pronounced for the cortex compared with the whole-kidney analysis. : Functional MR imaging of the kidneys demonstrates increased R2* in the inner medulla only after the administration of the iodixanol potentially indicating hypoxia and thus a pathomechanism of contrast-induced nephropathy.

• Renal BOLD-MRI does not reflect renal function in chronic kidney disease.

  Authors: Henrik J Michaely, Linda Metzger, Stefan Haneder, Jan Hansmann, Stefan O Schoenberg, Ulrike I Attenberger

  Kidney international. 01/2012;

  Renal blood oxygen level-dependent magnetic resonance imaging (BOLD-MRI) is a noninvasive fast technique to characterize renal function. Here we evaluated the impact of renal function on theRenal blood oxygen level-dependent magnetic resonance imaging (BOLD-MRI) is a noninvasive fast technique to characterize renal function. Here we evaluated the impact of renal function on the relaxation rate (R2(*)) in the cortex and medulla to provide baseline data for further use of renal BOLD-MRI. This parameter was evaluated in 400 patients scheduled for abdominal imaging who underwent transversal blood oxygen level-dependent measurements with a multi-echo gradient-echo sequence with 12 echo times. The loss of phase coherence (T2(*)) maps were generated in which kidney regions of interest were selected to differentiate the medulla and cortex, and R2(*) was equated to 1/T2(*). Individual R2(*) values were, in turn, correlated to the eGFR (MDRD formula of 280 patients with available serum creatinine measurements), age, and gender each for 1.5 and 3.0 T field-strength scans of 342 patients. At both the field strengths, no significant differences in R2(*) of the cortex and medulla were found between patient gender, age, eGFR, or between different stages of chronic kidney disease determined using the KDOQI system. Thus, BOLD-MRI of a non-specific patient population failed to discriminate between the patients with various stages of chronic kidney disease.Kidney International advance online publication, 11 January 2012; doi:10.1038/ki.2011.455.

• Implementation of Dual-Source RF Excitation in 3 T MR-Scanners Allows for Nearly Identical ADC Values Compared to 1.5 T MR Scanners in the Abdomen.

  Authors: Raghuram K Rao, Philipp Riffel, Mathias Meyer, Paul J Kettnaker, Andreas Lemke, Stefan Haneder, Stefan O Schoenberg, Henrik J Michaely

  PloS one. 01/2012; 7(2):e32613.

  To retrospectively and prospectively compare abdominal apparent diffusion coefficient (ADC) values obtained within in a 1.5 T system and 3 T systems with and without dual-source parallel RFTo retrospectively and prospectively compare abdominal apparent diffusion coefficient (ADC) values obtained within in a 1.5 T system and 3 T systems with and without dual-source parallel RF excitation techniques. After IRB approval, diffusion-weighted (DW) images of the abdomen were obtained on three different MR systems (1.5 T, a first generation 3 T, and a second generation 3 T which incorporates dual-source parallel RF excitation) on 150 patients retrospectively and 19 volunteers (57 examinations total) prospectively. Seven regions of interest (ROI) were throughout the abdomen were selected to measure the ADC. Statistical analysis included independent two-sided t-tests, Mann-Whitney U tests and correlation analysis. In the DW images of the abdomen, mean ADC values were nearly identical with nonsignificant differences when comparing the 1.5 T and second generation 3 T systems in all seven anatomical regions in the patient population and six of the seven in the volunteer population (p>0.05 in all distributions). The strength of correlation measured in the volunteer population between the two scanners in the kidneys ranged from r = 0.64-0.88 and in the remaining regions (besides the spleen), r>0.85. In the patient population the first generation 3 T scanner had different mean ADC values with significant differences (p<0.05) compared to the other two scanners in each of the seven distributions. In the volunteer population, the kidneys shared similar ADC mean values in comparison to the other two scanners with nonsignificant differences. A second generation 3 T scanner with dual-source parallel RF excitation provides nearly identical ADC values compared with the 1.5 T imaging system in abdominal imaging.

• Dual-energy CT angiography of the lungs: comparison of test bolus and bolus tracking techniques for the determination of scan delay.

  Authors: Thomas Henzler, Mathias Meyer, Miriam Reichert, Radko Krissak, John W Nance, Stefan Haneder, Stefan O Schoenberg, Christian Fink

  European journal of radiology. 01/2012; 81(1):132-8.

  To prospectively compare test bolus and bolus tracking for the determination of scan delay of pulmonary dual-energy CT angiography in patients with suspected pulmonary embolism. 60 consecutiveTo prospectively compare test bolus and bolus tracking for the determination of scan delay of pulmonary dual-energy CT angiography in patients with suspected pulmonary embolism. 60 consecutive patients referred for CTA for exclusion of PE were randomized either into a test bolus group or into a bolus tracking group. All exams were performed on a 64-channel dual source CT scanner. A standard single-acquisition dual-energy CTA was performed after injection of 100ml Iomeprol 400 followed by a saline chaser of 4 ml/s. The scan delay was determined using either test bolus (n=30) or bolus tracking (n=30). Test bolus was performed using an additional 20 ml Iomeprol 400 injected with a rate of 4 ml/s during acquisition of a series of dynamic low-dose monitoring scans followed by injection of a saline bolus of 20 ml using the same flow rate. For DECT angiography of the lungs 100ml Iomeprol 400 was injected with an injection rate of 4 ml/s followed by a saline chaser of 20 ml using the same flow rate. Attenuation profiles of different vascular segments (pulmonary arteries, pulmonary parenchyma, aorta, all 4 heart chambers) were measured to evaluate the timing techniques. Overall image quality of dual-energy "perfusion" maps and virtual 120 kV CTA images was evaluated by two radiologists regarding the present of artifacts. In all patients an adequate and homogeneous contrast enhancement of more than 400 Hounsfield units (HU) was achieved in the different vascular districts. No statistically significant difference between test bolus and bolus tracking was found regarding vessel attenuation or overall image quality. A homogeneous opacification of the different vascular territories and the pulmonary parenchyma as well as a sufficient image quality can be achieved with either bolus tracking or test bolus techniques.

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• Combined large field-of-view MRA and time-resolved MRA of the lower extremities: Impact of acquisition order on image quality.

  Authors: Philipp Riffel, Stefan Haneder, Ulrike I Attenberger, Joachim Brade, Stefan O Schoenberg, Henrik J Michaely

  European journal of radiology. 12/2011;

  PURPOSE: Different approaches exist for hybrid MRA of the calf station. So far, the order of the acquisition of the focused calf MRA and the large field-of-view MRA has not been scientificallyPURPOSE: Different approaches exist for hybrid MRA of the calf station. So far, the order of the acquisition of the focused calf MRA and the large field-of-view MRA has not been scientifically evaluated. Therefore the aim of this study was to evaluate if the quality of the combined large field-of-view MRA (CTM MR angiography) and time-resolved MRA with stochastic interleaved trajectories (TWIST MRA) depends on the order of acquisition of the two contrast-enhanced studies. METHODS: In this retrospective study, 40 consecutive patients (mean age 68.1±8.7 years, 29 male/11 female) who had undergone an MR angiographic protocol that consisted of CTM-MRA (TR/TE, 2.4/1.0ms; 21° flip angle; isotropic resolution 1.2mm; gadolinium dose, 0.07mmol/kg) and TWIST-MRA (TR/TE 2.8/1.1; 20° flip angle; isotropic resolution 1.1mm; temporal resolution 5.5s, gadolinium dose, 0.03mmol/kg), were included. In the first group (group 1) TWIST-MRA of the calf station was performed 1-2min after CTM-MRA. In the second group (group 2) CTM-MRA was performed 1-2min after TWIST-MRA of the calf station. The image quality of CTM-MRA and TWIST-MRA were evaluated by 2 two independent radiologists in consensus according to a 4-point Likert-like rating scale assessing overall image quality on a segmental basis. Venous overlay was assessed per examination. RESULTS: In the CTM-MRA, 1360 segments were included in the assessment of image quality. CTM-MRA was diagnostic in 95% (1289/1360) of segments. There was a significant difference (p<0.0001) between both groups with regard to the number of segments rated as excellent and moderate. The image quality was rated as excellent in group 1 in 80% (514/640 segments) and in group 2 in 67% (432/649), respectively (p<0.0001). In contrast, the image quality was rated as moderate in the first group in 5% (33/640) and in the second group in 19% (121/649) respectively (p<0.0001). The venous overlay was disturbing in 10% in group 1 and 20% in group 2 (p=n.s.). CONCLUSION: If a combined hybrid MRA approach with large field-of-view and time-resolved MRA is acquired the large field-of-view MRA should be acquired first in order for optimal image quality.

• DCE-MRI of the human kidney using BLADE: A feasibility study in healthy volunteers.

  Authors: Florian Lietzmann, Frank G Zöllner, Ulrike I Attenberger, Stefan Haneder, Henrik J Michaely, Lothar R Schad

  Journal of magnetic resonance imaging : JMRI. 11/2011;

  PURPOSE: To evaluate the degree of motion compensation in the kidney using two different sampling methods, each in their optimized settings: A BLADE k-space acquisition technique and a routinely usedPURPOSE: To evaluate the degree of motion compensation in the kidney using two different sampling methods, each in their optimized settings: A BLADE k-space acquisition technique and a routinely used kidney perfusion acquisition scheme (TurboFLASH). MATERIALS AND METHODS: Dynamic contrast enhanced magnetic resonance examinations were performed in 16 healthy volunteers on a 3 Tesla MR-system with two parameterizations of the BLADE sequence and the standard reference acquisition scheme. Signal intensity enhanced time curves were analyzed with a mathematical model and a widely published separable compartment model on cortex regions to assess robustness versus motion artifacts. RESULTS: BLADE-measurements with a strip-width of 32 lines constituted the smallest mean values for the sum of squared errors (6065 ± 4996) compared with the measurement with a strip-width of 64 lines (13849 ± 14079) or the standard TurboFLASH (11884 ± 8076). Calculations concerning goodness of the fit of the applied compartment model yielded an overall average of the Akaike Fit Error of 732 ± 141 for BLADE (646 ± 149 for a strip-width of 32 lines, 816 ± 53 for 64 lines) and 1626 ± 303 for the TurboFLASH (TFL) sequence. CONCLUSION: We demonstrated that renal dynamic contrast enhanced magnetic resonance imaging using BLADE k-space sampling with a strip-width of 32 is significantly less sensitive to motion than a widely published Turbo-Flash sequence with nearly similar parameters. J. Magn. Reson. Imaging 2011;. © 2011 Wiley Periodicals, Inc.

• Quantitative and qualitative (23)Na MR imaging of the human kidneys at 3 T: before and after a water load.

  Authors: Stefan Haneder, Simon Konstandin, John N Morelli, Armin M Nagel, Frank G Zoellner, Lothar R Schad, Stefan O Schoenberg, Henrik J Michaely

  Radiology. 09/2011; 260(3):857-65.

  To qualitatively and quantitatively assess the corticomedullary sodium 23 ((23)Na) concentration in human kidneys before and after oral administration of a water load by using 3-T magnetic resonanceTo qualitatively and quantitatively assess the corticomedullary sodium 23 ((23)Na) concentration in human kidneys before and after oral administration of a water load by using 3-T magnetic resonance (MR) imaging. Fourteen healthy volunteers (mean age, 28 years; range, 24-34 years) were included in this institutional review board-approved study between July and December 2009. For (23)Na MR imaging, a density-adapted three-dimensional radial gradient echo sequence (echo time, 0.55 msec; repetition time, 120 msec; spatial resolution, 5 × 5 × 5 mm) was used with a dedicated (23)Na-tuned coil. Beforehand, the coil profile was assessed by using phantom measurements, and the volunteer images were mathematically corrected accordingly. Images of the volunteers were obtained before and 30 minutes after oral ingestion of 1 L of water. As internal reference, (23)Na concentration of the cerebrospinal fluid (CSF) was calculated. Well-defined corticomedullary complexes in each kidney were assessed, with (23)Na concentrations in the cortex and medulla assessed at various standardized points. From these values, quantitative (23)Na concentrations were derived, and the slopes of the linear portion of the concentration gradient were calculated. Paired t tests were performed. Mean calculated (23)Na concentrations of CSF before (135.2 mmol/L ± 10.4) and after water load (135.5 mmol/L ± 11.0) fell within physiologic ranges (P = .95). An increase in average (23)Na concentration from 63.5 mmol/L ± 9.3 in the cortex to 108.0 mmol/L ± 10.9 in the medulla was identified. After the water load, this gradient was preserved, although (23)Na concentrations decreased significantly (P < .0001) to 48.6 mmol/L ± 5.3 in the cortex and 81.9 mmol/L ± 10.1 in the medulla-declines of 23.4% and 24.7%, respectively. This study demonstrates the physiologic evaluation of human kidneys with 3-T (23)Na MR imaging. The (23)Na imaging technique used allows the quantification of the corticomedullary (23)Na concentration and the assessment of its change with differing physiologic conditions.

• Gadofosveset: parameter optimization for steady-state imaging of the thoracic and abdominal vasculature.

  Authors: Stefan Haneder, Ulrike I Attenberger, Andreas Biffar, Olaf Dietrich, Christian Fink, Stefan O Schoenberg, Henrik J Michaely

  Investigative radiology. 06/2011; 46(11):678-85.

  Comparison of 3 optimized pulse sequences for thoracoabdominal contrast-enhanced magnetic-resonance angiography by signal-to-noise measurements and time-dependent T1 mapping in the steady state afterComparison of 3 optimized pulse sequences for thoracoabdominal contrast-enhanced magnetic-resonance angiography by signal-to-noise measurements and time-dependent T1 mapping in the steady state after injection of 0.03 mmol/kg BW gadofosveset. After institutional review board approval, 15 healthy volunteers (19-46 years, mean age: 31.5 years) were included in this prospective, intraindividual comparison study. All examinations were performed at 1.5 T. Three pulse sequences: volume interpolated breath-hold examination (VIBE) sequences as VIBESEMI (echo time [TE]: 1.64 milliseconds, repetition time [TR]: 3.77 milliseconds, FA: 15 degrees, voxel size: 1.2 × 1.2 × 1.2 mm) with short TR, VIBEOPT (TE: 2.2 milliseconds, TR: 5.2, FA: 15 degree, voxel size: 1.2 × 1.2 × 1.2 mm) with long TR, and a typical 3-dimensional fast low angle shot (FLASH) sequence (TE: 1.39 milliseconds, TR: 3.77 milliseconds, FA: 25 degree, voxel size: 1.0 × 0.8 × 1.0 mm) were repeated 10, 20, 30, and 40 minutes after the injection of 0.03 mmol/kg BW gadofosveset (mean dose: 9.7 mL). Mean signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were computed for the aorta and the inferior vena cava (IVC). Three-dimensional gradient echo sequences with variable flip angles were performed for T1 mapping 0 to 50 minutes postinjection (p.i.). Additional phantom measurements were performed to compare the sequences. Significantly higher SNR values of the FLASH were found at every point compared with VIBEOPT (P = 0.002-P = 0.004), but only 10, respectively, 20 minutes p.i. to VIBESEMI. No significant differences of SNR were obtained between VIBESEMI and VIBEOPT. In the aorta, the maximal percentage gain of SNR was 29.2% for 3D-FLASH compared with VIBESEMI. Similar, but mostly not significant, results were obtained regarding the SNR in the IVC with the 3D-FLASH sequence yielding higher SNR versus both comparators (P = 0.007-P = 0.466). Except 10 minutes p.i., CNR analysis yielded higher values for the VIBESEMI versus both comparators in the aorta as well as in the IVC. No statistical significant difference was found for the VIBESEMI versus the 3D-FLASH sequence in all comparisons. Regarding the phantom measurements, statistically significant higher SNR was found for the VIBESEMI versus the 3D-FLASH. The T1 time in the aorta decreased p.i. from 1227 ± 383 milliseconds to 141 ± 27 milliseconds and showed over the time a slow reincrease to 175 ± 29 milliseconds at 50 minutes p.i. Ten to 30 minutes after injection of gadofosveset, a relatively constant longitudinal relaxation is given. In this steady state, no additional improvements were obtained by theoretically optimized sequence parameters in the VIBEOPT with a longer TR.

• First multimodal embolization particles visible on x-ray/computed tomography and magnetic resonance imaging.

  Authors: Soenke H Bartling, Johannes Budjan, Hagit Aviv, Stefan Haneder, Bettina Kraenzlin, Henrik Michaely, Shlomo Margel, Steffen Diehl, Wolfhard Semmler, Norbert Gretz, Stefan O Schönberg, Maliha Sadick

  Investigative radiology. 03/2011; 46(3):178-86.

  Embolization therapy is gaining importance in the treatment of malignant lesions, and even more in benign lesions. Current embolization materials are not visible in imaging modalities. However, it isEmbolization therapy is gaining importance in the treatment of malignant lesions, and even more in benign lesions. Current embolization materials are not visible in imaging modalities. However, it is assumed that directly visible embolization material may provide several advantages over current embolization agents, ranging from particle shunt and reflux prevention to improved therapy control and follow-up assessment. X-ray- as well as magnetic resonance imaging (MRI)-visible embolization materials have been demonstrated in experiments. In this study, we present an embolization material with the property of being visible in more than one imaging modality, namely MRI and x-ray/computed tomography (CT). Characterization and testing of the substance in animal models was performed. To reduce the chance of adverse reactions and to facilitate clinical approval, materials have been applied that are similar to those that are approved and being used on a routine basis in diagnostic imaging. Therefore, x-ray-visible Iodine was combined with MRI-visible Iron (Fe3O4) in a macroparticle (diameter, 40-200 μm). Its core, consisting of a copolymerized monomer MAOETIB (2-methacryloyloxyethyl [2,3,5-triiodobenzoate]), was coated with ultra-small paramagnetic iron oxide nanoparticles (150 nm). After in vitro testing, including signal to noise measurements in CT and MRI (n = 5), its ability to embolize tissue was tested in an established tumor embolization model in rabbits (n = 6). Digital subtraction angiography (DSA) (Integris, Philips), CT (Definition, Siemens Healthcare Section, Forchheim, Germany), and MRI (3 Tesla Magnetom Tim Trio MRI, Siemens Healthcare Section, Forchheim, Germany) were performed before, during, and after embolization. Imaging signal changes that could be attributed to embolization particles were assessed by visual inspection and rated on an ordinal scale by 3 radiologists, from 1 to 3. Histologic analysis of organs was performed. Particles provided a sufficient image contrast on DSA, CT (signal to noise [SNR], 13 ± 2.5), and MRI (SNR, 35 ± 1) in in vitro scans. Successful embolization of renal tissue was confirmed by catheter angiography, revealing at least partial perfusion stop in all kidneys. Signal changes that were attributed to particles residing within the kidney were found in all cases in all the 3 imaging modalities. Localization distribution of particles corresponded well in all imaging modalities. Dynamic imaging during embolization provided real-time monitoring of the inflow of embolization particles within DSA, CT, and MRI. Histologic visualization of the residing particles as well as associated thrombosis in renal arteries could be performed. Visual assessment of the likelihood of embolization particle presence received full rating scores (153/153) after embolization. Multimodal-visible embolization particles have been developed, characterized, and tested in vivo in an animal model. Their implementation in clinical radiology may provide optimization of embolization procedures with regard to prevention of particle misplacement and direct intraprocedural visualization, at the same time improving follow-up examinations by utilizing the complementary characteristics of CT and MRI. Radiation dose savings can also be considered. All these advantages could contribute to future refinements and improvements in embolization therapy. Additionally, new approaches in embolization research may open up.

• Peripheral MRA with continuous table movement: imaging speed and robustness compared to a conventional stepping table technique.

  Authors: Katrin Koziel, Ulrike I Attenberger, Kai Lederle, Stefan Haneder, Stefan O Schoenberg, Henrik J Michaely

  European journal of radiology. 02/2011; 80(2):537-42.

  To investigate the potential of continuous table movement (CTM)-MRA for reduction of acquisition time and to evaluate the image quality in comparison to conventional stepping table (CST) MRA. TheTo investigate the potential of continuous table movement (CTM)-MRA for reduction of acquisition time and to evaluate the image quality in comparison to conventional stepping table (CST) MRA. The data of 82 patients were included in this retrospective, IRB-approved study. All patients underwent peripheral MRA at our institution. 41 consecutive patients were examined with a CST-MRA at a 1.5 T MR system. 41 different consecutive patients were examined with a CTM-MRA at 3.0 T MR system. Image quality was assessed by two independent radiologists in consensus on a 4-point Likert-type scale. Descriptive statistics and t-tests were used to compare image acquisition time of CST-MRA to that of CTM-MRA with and without additional time-resolved imaging of the feet using the TWIST technique. Additionally, acquisition time was compared in a subgroup of the fastest 50%. The mean imaging time for the CTM-MRA was 34% less than with the CST-MRA (18.2 min vs. 27.5 min; p<0.0001). Even with inclusion of the TWIST sequence the combined CTM-/TWIST-MRA protocol was 26% faster (20.3 min vs. 27.5 min; p<0.0001). The image quality was slightly better with CTM-MRA (CTM-MRA mean score 3.3±0.5, mean score CST-MRA 2.9±0.6). Venous overlay was significantly lower using the CTM-MRA approach (CTM-MRA mean score 2.8±0.4; CST-MRA mean score 2.2±0.7; p<0.0001). CTM-MRA is on average 30% faster than a comparable CST-MRA protocol with equal image quality. Even when adding an additional time-resolved-MRA of the calf station the CTM-MRA protocol is still 26% faster. In conclusion, this study proves that CTM-MRA further improves MRA by reducing user interference and image acquisition times and hence allowing to increase the clinical throughput.

• Feasibility of renal sodium MRI in an acute tubular necrosis model at 3 Tesla

  Authors: Raffi Kalayciyan, Friedrich Wetterling, Simon Konstandin, Tobias Runge, Urs Benck, Stefan Haneder, Henrik Michaely, Lothar Rudi Schad

  MAGMA Magnetic Resonance Materials in Physics Biology and Medicine. 01/2011; 24:167-168.

• Magnetic resonance angiography (MRA) of the calf station at 3.0 T: intraindividual comparison of non-enhanced ECG-gated flow-dependent MRA, continuous table movement MRA and time-resolved MRA.

  Authors: Stefan Haneder, Ulrike I Attenberger, Philipp Riffel, Thomas Henzler, Stefan O Schoenberg, Henrik J Michaely

  European radiology. 01/2011; 21(7):1452-61.

  To compare 3D non-enhanced ECG-gated inflow-dependent MRA (NE-MRA) vs. continuous table movement (CTM) MR-angiography and time-resolved TWIST-MRA in the calf station at 3.0 T in a clinical patientTo compare 3D non-enhanced ECG-gated inflow-dependent MRA (NE-MRA) vs. continuous table movement (CTM) MR-angiography and time-resolved TWIST-MRA in the calf station at 3.0 T in a clinical patient collective. 36 patients (27 male/9 female, 66.1 ± 14.4 years) with PAOD (stage II-IV) underwent during a single MRI: NE-MRA, contrast-enhanced CTM-MRA and TWIST-MRA with a single dose of a gadolinium-based contrast agent. The image quality (IQ) and the degree of stenoses were rated on a four-point scale. Positive (PPV) and negative predictive values (NPV), sensitivity (SS) and specificity (SP) for stenoses detection were calculated for NE-MRA vs. CTM-MRA and vs. TWIST-MRA. Values were obtained for overall graduation of wall changes and for severe stenoses (>70%). With NE-MRA 122/288 segments were not assessable. Compared with CTM-MRA and TWIST-MRA the IQ was significantly inferior (p < 0.0001 to p = 0.0426). CTM-MRA/TWIST-MRA detected stenoses in 44.9%/46.1% of the segments, NE-MRA in 53.5%. SS/NPV of the NE-MRA ranged from 97.8 to 100%. The SP and PPV ranged from 72.7 to 85.5% and 66.7 to 78.2%. Contrast-enhanced MRA techniques are superior to NE-MRA regarding IQ and correct identification of stenoses. If technically successful, NE-MRA is characterised by high NPV and overestimation of the degree of stenoses.

• Peripheral arterial occlusive disease: evaluation of a high spatial and temporal resolution 3-T MR protocol with a low total dose of gadolinium versus conventional angiography.

  Authors: Ulrike I Attenberger, Stefan Haneder, John N Morelli, Steffen J Diehl, Stefan O Schoenberg, Henrik J Michaely

  Radiology. 10/2010; 257(3):879-87.

  To evaluate a peripheral magnetic resonance (MR) angiographic protocol combining continuous table movement (CTM) MR angiography of the entire runoff vasculature with time-resolved (TWIST) 3-T MRTo evaluate a peripheral magnetic resonance (MR) angiographic protocol combining continuous table movement (CTM) MR angiography of the entire runoff vasculature with time-resolved (TWIST) 3-T MR angiography of the calves with a total gadolinium dose of 0.1 mmol per kilogram of body weight. In this retrospective institutional review board-approved study, 31 consecutive patients (22 men, nine women; mean age, 65 years ± 14 [standard deviation]) with peripheral arterial occlusive disease who had undergone a low-dose MR angiographic protocol that consisted of CTM MR angiography (repetition time msec/echo time msec, 2.4/1.0; 21° flip angle; voxel size, 1.2 mm(3); gadolinium dose, 0.07 mmol per kilogram of body weight) and TWIST MR angiography (2.8/1.1; 20° flip angle; voxel size, 1.1 mm(3); temporal resolution, 4.8-5.5 sec, gadolinium dose, 0.03 mmol/kg), as well as digital subtraction angiography (DSA), were included. Two radiologists rated image quality and stenosis degree on four-point scales. The accuracy of stenosis gradation and, specifically, the detection of high-grade stenoses (stenosis of 70%-99%) with CTM MR angiography alone and with the combined protocol were compared with accuracy of stenosis gradation and detection of high-grade stenoses with DSA. Means and standard deviations were calculated for all data. Interobserver agreement was determined with κ statistics. Positive and negative predictive values, sensitivity, specificity, and overall diagnostic accuracy were calculated for CTM MR angiography alone and for the combined protocol. For CTM MR angiography, image quality was good or excellent in 95.9% of vessel segments; for TWIST MR angiography, image quality was good or excellent in 94.3% and 97.8% of vessel segments for readers 1 and 2, respectively. The combined protocol resulted in high overall diagnostic accuracy of more than 80% for detection of stenosis and diagnostic accuracy of 93.5% for detection of high-grade vessel stenosis. Inclusion of TWIST MR angiography increased diagnostic value over that achieved with CTM MR angiography alone. A combined MR angiographic approach in which a low total gadolinium dose (0.1 mmol/kg) is used yields excellent image quality and is accurate in the diagnosis of peripheral arterial stenosis.

• [Blood oxygenation level dependent (BOLD)--renal imaging: concepts and applications].

  Authors: Johanna C Nissen, Moritz B Mie, Frank G Zöllner, Stefan Haneder, Stefan O Schoenberg, Henrik J Michaely

  Zeitschrift für medizinische Physik. 01/2010; 20(2):88-100.

  Many renal diseases as well as several pharmacons cause a change in renal blood flow and/or renal oxygenation. The blood oxygenation level dependent (BOLD) imaging takes advantage of local fieldMany renal diseases as well as several pharmacons cause a change in renal blood flow and/or renal oxygenation. The blood oxygenation level dependent (BOLD) imaging takes advantage of local field inhomogeneities and is based on a T2*-weighted sequence. BOLD is a non-invasive method allowing an estimation of the renal, particularly the medullary oxygenation, and an indirect measurement of blood flow without administration of contrast agents. Thus, effects of different drugs on the kidney and various renal diseases can be controlled and observed. This work will provide an overview of the studies carried out so far and identify ways how BOLD can be used in clinical studies.

• Peripheral Magnetic Resonance Angiography With Continuous Table Movement in Combination With High Spatial and Temporal Resolution Time-Resolved MRA With a Total Single Dose (0.1 mmol/kg) of Gadobutrol at 3.0 T.

  Authors: Matthias Voth, Stefan Haneder, Kurt Huck, Alexandra Gutfleisch, Stefan Schoenberg, Henrik Michaely

  Investigative radiology. 08/2009;

  PURPOSE:: To prove the concept of peripheral continuous table movement (CTM) MR-angiography (MRA) in combination with high spatial and temporal resolution time-resolved TWIST-MRA in a singlePURPOSE:: To prove the concept of peripheral continuous table movement (CTM) MR-angiography (MRA) in combination with high spatial and temporal resolution time-resolved TWIST-MRA in a single MR-examination at 3.0 T with a single dose (0.1 mmol/kg) of gadobutrol in total. MATERIALS AND METHODS:: We included 22 consecutive patients (15 m/7 f, mean age: 64 years) referred for peripheral MRA with clinical symptoms of peripheral arterial occlusive disease Fontaine stages II-IV. All of them underwent both CTM-MRA (TR: 2.4 ms/TE: 1.0 ms/flip angle: 21 degree) of the entire run-off vessels and TWIST-MRA (TR: 2.8 ms/TE: 1.1 ms/flip angle: 20 degree) of the calf station during a single MR-examination. All examinations were performed on a 3.0 T MR system (Tim Trio). Spatial resolution of the CTM-MRA datasets was technically limited to an acquired resolution of 1.2 x 1.2 x 1.96 mm reconstructed to 1.2 mm isotropic. The TWIST-MRA was acquired with 1.1 x 1.1 x 1.35 mm and reconstructed to 1.1 mm isotropic with a temporal resolution of 5.5 seconds in the calf station. A total of 0.1 mmol/kg BW gadobutrol diluted 1:1 with saline was injected at a flow rate of 1.5 mL/s of which 0.07 mmol/kg was administered for the CTM-MRA and 0.03 mmol/kg for the TWIST-MRA.CTM-MRA run off datasets were qualitatively assessed using a 4 point scale (4 = excellent, 1 = nondiagnostic) followed by TWIST-MRA datasets for the calf using the same scale. Additional relevant findings only visible in the TWIST-MRA were documented. RESULTS:: All datasets could be evaluated with a total of 397 assessable segments. CTM-MRA was diagnostic in 99% (393/397 segments) with image quality judged as excellent in 54% (213/397 segments), good in 42% (14/397), and moderate in 4% (14/397) of analyzed segments respectively. Nondiagnostic image quality was seen in 1% (4/397 segments). Venous overlay in the calf station was found in 27% (6/22 patients). TWIST-MRA was diagnostic in 100% (115/115 segments), throughout with good or excellent image quality. In 14 of 22 patients additional relevant findings were detected by TWIST-MRA. CONCLUSION:: Single-dose gadobutrol CTM-MRA in combination with a high spatial and temporal resolution TWIST-MRA at 3.0 T is a reliable technique with good image quality. Despite the use of single dose contrast agent large field of view coverage and dynamic images can be acquired. Because of its robustness, this imaging approach of the vasculature has great potential for a broad clinical use.