Publications (43)103.86 Total impact
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Article: MRA of the foot with a blood pool agent
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ABSTRACT: Foot complications associated with diabetes are the most common cause of non-traumatic lower-extremity amputations in the industrialised countries. Revascularisation techniques require precise preoperative imaging. Magnetic resonance angiography (MRA) using gadofosveset trisodium (Vasovist, Bayer Schering Pharma AG, Berlin, Germany) has the potential to detect significantly more patent pedal vessel segments than selective digital substractive angiography (DSA) in an examination with two blinded readers. MRI and MRA are the imaging methods of choice for differentiated assessment of the diabetic foot and its complications, and they are robust techniques for delineating the pedal macrocirculation. Therefore, they should play a central role in the management of patients with a diabetic foot syndrome.European Radiology Supplements 04/2012; 18:21-25. -
Article: Diagnostic performance of state-of-the-art imaging techniques for morphological assessment of vascular abnormalities in patients with chronic thromboembolic pulmonary hypertension (CTEPH).
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ABSTRACT: To determine the most comprehensive imaging technique for the assessment of pulmonary arteries in patients with chronic thromboembolic pulmonary hypertension (CTEPH). 24 patients with CTEPH were examined by ECG-gated multi-detector CT angiography (MD-CTA), contrast-enhanced MR angiography (ce-MRA) and selective digital subtraction angiography (DSA) within 3 days. Two readers in consensus separately evaluated each imaging technique (48 main, 144 lobar and 449 segmental arteries) for typical changes like complete obstructions, vessel cut-offs, intimal irregularities, incorporated thrombus formations, and bands and webs. A joint interpretation of all three techniques served as a reference standard. Based on image quality, there was no non-diagnostic examination by either imaging technique. DSA did not sufficiently display 1 main, 3 lobar and 4 segmental arteries. The pulmonary trunk was not assessable by DSA. One patient showed thrombotic material at this level only by MD-CTA and MRA. Sensitivity and specificity of MD-CTA regarding CTEPH-related changes at the main/lobar and at the segmental levels were 100%/100% and 100%/99%, of ce-MRA 83.1%/98.6% and 87.7%/98.1%, and of DSA 65.7%/100% and 75.8%/100%, respectively. ECG-gated MD-CTA proved the most adequate technique for assessment of the pulmonary arteries in the diagnostic work-up of CTEPH patients. • A prospective single-centre study evaluated ECG-gated MDCTA, ce-MRA and DSA in CTEPH patients. • ECG-gated MD-CT angiography outperformed DSA and ce-MRA. • Right heart catheterisation should be reserved only for assessment of pulmonary haemodynamics.European Radiology 09/2011; 22(3):607-16. · 3.22 Impact Factor -
Article: Rectal cancer: mucinous carcinoma on magnetic resonance imaging indicates poor response to neoadjuvant chemoradiation.
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ABSTRACT: To assess response of locally advanced rectal carcinoma to chemoradiation with regard to mucinous status and local tumor invasion found at pretherapeutic magnetic resonance imaging (MRI). A total of 88 patients were included in this prospective study of patients with advanced mrT3 and mrT4 carcinomas. Carcinomas were categorized by MRI as mucinous (mucin proportion >50% within the tumor volume), and as nonmucinous. Patients received neoadjuvant chemoradiation consisting of 50.4 Gy (1.8 Gy/fraction) and 5-fluorouracil on Days 1 to 5 and Days 29 to 33. Therapy response was assessed by comparing pretherapeutic MRI with histopathology of surgical specimens (minimum distance between outer tumor edge and circumferential resection margin = CRM, T, and N category). A mucinous carcinoma was found in 21 of 88 patients. Pretherapeutic mrCRM was 0 mm (median) in the mucinous and nonmucinous group. Of the 88 patients, 83 underwent surgery with tumor resection. The ypCRM (mm) at histopathology was significantly lower in mucinous carcinomas than in nonmucinous carcinomas (p ≤ 0.001). Positive resection margins (ypCRM ≤ 1 mm) were found more frequently in mucinous carcinomas than in nonmucinous ones (p ≤ 0.001). Treatment had less effect on local tumor stage in mucinous carcinomas than in nonmucinous carcinomas (for T downsizing, p = 0.012; for N downstaging, p = 0.007). Disease progression was observed only in patients with mucinous carcinomas (n = 5). Mucinous status at pretherapeutic MRI was associated with a noticeably worse response to chemoradiation and should be assessed by MRI in addition to local tumor staging to estimate response to treatment before it is initiated.International journal of radiation oncology, biology, physics 01/2011; 82(2):842-8. · 4.59 Impact Factor -
Article: Gene therapy with iNOS enhances regional contractility and reduces delayed contrast enhancement in a model of postischemic congestive heart failure.
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ABSTRACT: The purpose of this study was to evaluate the effect of transient local myocardial gene transfer of iNOS on cardiac function in a large mammal animal model of heart failure induced by chronic ischemia. Chronic myocardial ischemia was induced using a minimally invasive model in 16 landrace pigs. Upon demonstration of heart failure, eight animals were treated with liposome-mediated iNOS-gene-transfer by local intramyocardial injection; eight animals received a sham procedure to serve as control. The transmurality of late enhancement (control: 46.4%, iNOS: 35.9%; p < 0.05) was significantly decreased in the ischemic area in the iNOS-treated group. Wall thickness at end-systole (6.8 mm vs. 5.9 mm, p < 0.001) and at end-diastole (5.4 mm vs. 4.2 mm, p < 0.001) were significantly higher in the therapy group. Additionally, the regional wall motion at the level of the ischemic region was 3.5 mm in the therapy group while it was significantly less (3.0 mm, p < 0.001) in the control group. Our findings demonstrate that transient iNOS overexpression potentially leads to a significant decrease of regional late enhancement with a positive effect on regional cardiac function in the ischemic area in a large animal model of postischemic heart failure.Clinical hemorheology and microcirculation 01/2011; 49(1-4):271-8. · 3.40 Impact Factor -
Article: Comparison of the quantitative first pass myocardial perfusion MRI with and without prospective slice tracking: comparison between breath-hold and free-breathing condition.
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ABSTRACT: Physiologic motion of the heart is one of the major problems of myocardial blood flow quantification using first pass perfusion-MRI method. To overcome these problems, a perfusion pulse sequence with prospective slice tracking was developed. Cardiac motion was monitored by a navigator directly positioned at heart's basis to overcome no additional underlying model calculations connecting diaphragm and cardiac motion. Additional prescans were used before the perfusion measurement to detect slice displacements caused by remaining cardiac motion between navigator and the perfusion slice readout. The pulse sequence and subsequent quantification of myocardial blood flow was tested in healthy pigs with and without prospective slice tracking under both free-breathing and breath-hold conditions. To avoid influences by residual contrast agent concentration time courses were analyzed. Median myocardial blood flow values and interquartile ranges with prospective slice tracking under free-breathing and in a breath-hold were (1.04, interquartile range = 0.58 mL/min/g) and (1.20, interquartile range = 0.59 mL/min/g), respectively. This is in agreement with published positron emission tomography values. In measurements without prospective slice tracking (1.15, interquartile range = 1.58 mL/min/g), the interquartile range is significantly (P < 0.012) larger because of residual cardiac motion. In conclusion, prospective slice tracking reduces motion-induced variations of myocardial blood flow under both during breath-hold and under conditions of free-breathing.Magnetic Resonance in Medicine 11/2010; 64(5):1461-70. · 2.96 Impact Factor -
Article: A 34-year-old man with cardiac arrhythmias and lymphadenopathy.
Clinical Research in Cardiology 03/2010; 99(6):401-3. · 2.95 Impact Factor -
Article: MRI versus 64-row MDCT for diagnosis of hepatocellular carcinoma.
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ABSTRACT: To compare the diagnostic capability of multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI) for the detection of hepatocellular carcinoma (HCC) tumour nodules and their effect on patient management. A total of 28 patients (25 male, 3 female, mean age 67 +/- 10.8 years) with biopsy-proven HCC were investigated with 64-row MDCT (slice 3 mm native, arterial and portal-venous phase, 120 mL Iomeprol, 4 mL/s, delay by bolus trigger) and MRI (T1fs fl2d TE/TR 2.72/129 ms, T2tse TE/TR 102/4000 ms, 5-phase dynamic contrast-enhanced T1fs fl3d TE/TR 1.56/4.6, Gadolinium-DTPA, slice 4 mm). Consensus reading of both modalities was used as reference. Tumour nodules were analyzed with respect to number, size, and location. In total, 162 tumour nodules were detected by consensus reading. MRI detected significantly more tumour nodules (159 vs 123, P < 0.001) compared to MDCT, with the best sensitivity for early arterial phase MRI. False-negative CT findings included nodules < or = 5 mm ( n = 5), < or = 10 mm ( n = 17), < or = 15 mm ( n = 12 ), < or = 20 mm ( n = 4 ), and 1 nodule > 20 mm. MRI missed 2 nodules < or = 10 mm and 1 nodule < or = 15 mm. On MRI, nodule diameters were greater than on CT (29.2 +/- 25.1 mm, range 5-140 mm vs 24.1 +/- 22.7 mm, range 4-129 mm, P < 0.005). In 2 patients, MDCT showed only unilobar tumour spread, whereas MRI revealed additional nodules in the contralateral lobe. Detection of these nodules could have changed the therapeutic strategy. Contrast-enhanced MRI is superior to 64-row MDCT for the detection of HCC nodules. Patients should be allocated to interventional or operative treatment according to a dedicated MRI-protocol.World Journal of Gastroenterology 12/2009; 15(48):6044-51. · 2.47 Impact Factor -
Article: Quantitative contrast-enhanced myocardial perfusion magnetic resonance imaging: simulation of bolus dispersion in constricted vessels.
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ABSTRACT: Quantification of myocardial blood flow (MBF) by means of T1-weighted first-pass magnetic resonance imaging (MRI) requires knowledge of the arterial input function (AIF), which is usually estimated from the left ventricle (LV). Dispersion of the contrast agent bolus may occur between the LV and the tissue of interest, which leads to systematic underestimation of the MBF. The aim of this study was to simulate the dispersion along a simplified coronary artery with different stenoses. To analyze the dispersion in vessels with typical dimensions of coronary arteries, simulations were performed using the computational fluid dynamics approach. Simulations were accomplished on straight vessels with integrated stenoses of different degrees of area reduction and length as well as two different shapes-an axial symmetric and an asymmetric. Two boundary conditions were used representing myocardial blood flow at rest and under hyperemic conditions. The results under steady boundary conditions show that the dispersion is more pronounced in resting condition than during hyperemia yielding an underestimation of the MBF around 15% in the resting state and around 8% under stress conditions. At the outlet of the vessel an axial symmetric stenosis results in increased dispersion whereas an asymmetric stenosis yields a reduction. Due to the more severe dispersion, resting MBF may be more underestimated in quantitative myocardial perfusion MRI studies compared with MBF under stress conditions. In consequence the myocardial perfusion reserve may be overestimated. The amount of systematic error depends in a complex way on the shape and degree of stenoses.Medical Physics 08/2009; 36(7):3099-106. · 2.83 Impact Factor -
Article: Influence of Contrast Agent Dose and Image Acquisition Timing on the Quantitative Determination of Nonviable Myocardial Tissue Using Delayed Contrast‐Enhanced Magnetic Resonance Imaging
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ABSTRACT: Background: Delayed contrast‐enhanced magnetic resonance imaging (ceMRI) has been shown to identify areas of irreversible myocardial injury due to infarction (MI) with high spatial resolution, allowing precise quantification of nonviable (hyperenhanced) myocardium. The aim of our study was to investigate the size of nonviable myocardium quantitatively as a function of time post‐contrast when inversion time is held constant in patients post‐myocardial infarction using two contrast agent (CA) doses. Methods: Nine patients with chronic MI underwent two MR scans on a 1.5 Tesla system. Contrast‐enhanced MRI data in two short‐axis (SA) slices were continuously acquired until 40 minutes after CA injection [gadolinium diethylenetriamine pentaacetic acid (Gd‐DTPA), 0.1 mmol/kg body weight = single dose] interrupted only for a complete stack of SA slices encompassing the entire left ventricle (LV) between minutes 20 and 28. Left ventricular mass showing hyperenhancement was determined. The measurement was repeated on the subsequent day with double dose CA (0.2 mmol/kg body weight). Differences of signal intensities for hyperenhanced, nonhyperenhanced myocardium, and LV cavity were calculated. Results: Total mass of hyperenhancement from a complete SA stack acquired between minutes 20 and 28 was lower for single dose CA [9.0% vs. 14.2% for single and double dose, respectively (p = 0.03)]. Ten to 18 minutes after CA injection, there was no significant difference between the two doses and to an internal reference for both single and double dose. For single dose the image contrast between hyperenhancement and LV cavity was superior (minutes 10 to 16, p < 0.05) but inferior between hyperenhanced and nonhyperenhanced myocardium (minutes 6 to 16, p < 0.05). Conclusion: Myocardial infarct size measurements are a function of time postcontrast when inversion time is held constant regardless of the contrast agent dose. These data underscore the fact that a standardized imaging protocol that defines how the appropriate inversion time should be selected is needed for comparison of results obtained at various cMR sites.07/2009; 6(2):541-548. -
Article: Gadofosveset-enhanced MR angiography of the pedal arteries in patients with diabetes mellitus and comparison with selective intraarterial DSA.
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ABSTRACT: To compare gadofosveset-enhanced magnetic resonance angiography (MRA) of the pedal vasculature with selective intraarterial DSA. Eighteen patients with PAOD and type II diabetes were prospectively examined at 1.5 T. For contrast enhancement, 0.03 mmol/kg body weight gadofosveset was used. MR imaging consisted of dynamic and of high-resolution steady-state imaging. Selective digital subtraction angiography (DSA) was performed within 5 days and served as standard of reference. Image analysis was done by two observers. There were no differences between MRA and DSA regarding overall image quality. First-pass MRA detected significantly more patent vessel segments than did DSA (P<0.001, kappa=0.46). Interobserver agreement of MRA was very good with respect to the detection of patent vessel segments and the assessment of hemodynamically relevant stenoses (kappa=0.97 and 0.89, respectively). Steady-state imaging depicted significantly more patent metatarsal arteries than did dynamic imaging, and delineated inflammatory complications including osteomyelitis, soft-tissue abscesses, and fistulas related to the diabetic foot. Gadofosveset-enhanced MRA of the pedal vasculature proved to be superior to DSA. It offered a long imaging time window, and allowed for better depiction of the pedal outflow. Steady-state imaging delineated inflammatory complications associated with the diabetic foot.European Radiology 07/2009; 19(12):2993-3001. · 3.22 Impact Factor -
Article: Quantification of pulmonary blood flow (PBF): validation of perfusion MRI and nonlinear contrast agent (CA) dose correction with H(2)15O positron emission tomography (PET).
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ABSTRACT: Validation of quantification of pulmonary blood flow (PBF) with dynamic, contrast-enhanced MRI is still missing. A possible reason certainly lies in difficulties based on the nonlinear dependence of signal intensity (SI) from contrast agent (CA) concentration. Both aspects were addressed in this study. Nine healthy pigs were examined by first-pass perfusion MRI using gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA) and H(2)(15)O positron emission tomography (PET) imaging. Calculations of hemodynamic parameters were based on a one-compartment model (MR) and a two-compartment model (PET). Simulations showed a significant error when assuming a linear relation between MR SI and CA dose in the arterial input function (AIF), even at low doses of 0.025 mmol/kg body weight (BW). To correct for nonlinearity, a calibration curve was calculated on the basis of the signal equation. The required accuracy of equation parameters (like longitudinal relaxation time) was evaluated. Error analysis estimates <5% over-/underestimation of the corrected SI. Comparison of PET and MR flow values yielded a significant correlation (P < 0.001) in dorsal regions where signal-to-noise ratio (SNR) was sufficient. Changes in PBF due to the correction method were significant (P < 0.001) and resulted in a better agreement: mean values (standard deviation) in units of ml/min/100 ml lung tissue were 59 (15) for PET, 112 (28) for uncorrected MRI, and 80 (21) for corrected MRI.Magnetic Resonance in Medicine 06/2009; 62(2):476-87. · 2.96 Impact Factor -
Article: Usefulness of MRI to differentiate between temporary and long-term coronary artery occlusion in a minimally invasive model of experimental myocardial infarction.
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ABSTRACT: The surgical technique employed to determine an experimental ischemic damage is a major factor in the subsequent process of myocardial scar development. We set out to establish a minimally invasive porcine model of myocardial infarction using cardiac contrast-enhanced magnetic resonance imaging (ce-MRI) as the basic diagnostic tool. Twenty-seven domestic pigs were randomized to either temporary or permanent occlusion of the left anterior descending artery (LAD). Temporary occlusion was achieved by inflation of a percutaneous balloon in the left anterior descending artery directly beyond the second diagonal branch. Occlusion was maintained for 30 or 45 min, followed by reperfusion. Permanent occlusion was achieved via thrombin injection. Thirteen animals died peri- or postinterventionally due to arrhythmias. Fourteen animals survived the 30-min ischemia (four animals; group 1), the 45-min ischemia (six animals; group 2), or the permanent occlusion (4 animals; group 3). Coronary angiography and ce-MRI were performed 8 weeks after coronary occlusion to document the coronary flow grade and the size of myocardial scar tissue. The LAD was patent in all animals in groups 1 and 2, with normal TIMI flow; in group 3 animals, the LAD was totally occluded. Fibrosis of the left ventricle in group 1 (4.9 +/- 4.4%; p = 0.008) and group 2 (9.4 +/- 2.9%; p = 0.05) was significantly lower than in group 3 (14.5 +/- 3.9%). Wall thickness of the ischemic area was significantly lower in group 3 versus group 1 and group 2 (2.9 +/- 0.3, 5.9 +/- 0.7, and 6.1 +/- 0.7 mm; p = 0.005). The extent of late enhancement of the left ventricle was also significantly higher in group 3 (16.9 +/- 2.1%) compared to group 1 (5.3 +/- 5.4%; p = 0.003) and group 2 (9.7 +/- 3.4%, p = 0.013). In conclusion, the present model of minimally invasive infarction coupled with ce-MRI may represent a useful alternative to the open chest model for studies of myocardial infarction and scar development.CardioVascular and Interventional Radiology 06/2009; 32(5):1033-41. · 2.09 Impact Factor -
Chapter: Pulmonary Hypertension and Thromboembolic Disease
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ABSTRACT: Pulmonary hypertension (PH) is a disease group that includes a wide variety of reasons leading to an increased pulmonary arterial pressure. This chapter describes the basic mechanisms that lead to PH and the possibilities of MRI in diagnosing different aspects. A MR imaging protocol is provided making MRI a one-stop shop for classification of the underlying disease and assessment of hemodynamics.12/2008: pages 107-119; -
Article: Catheter ablation of an incessant ventricular tachycardia originating from the left aortic sinus cusp in an adolescent with subacute myocarditis.
Clinical Research in Cardiology 11/2008; 98(1):66-70. · 2.95 Impact Factor -
Article: Quantitative myocardial perfusion imaging using different autocalibrated parallel acquisition techniques.
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ABSTRACT: To compare three different autocalibrated parallel acquisition techniques (PAT) for quantitative and semiquantitative myocardial perfusion imaging. Seven healthy volunteers underwent myocardial first-pass perfusion imaging at rest using an SR-TrueFISP pulse sequence without PAT and while using GRAPPA, mSENSE, and TSENSE. signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), normalized upslopes (NUS), and myocardial blood flow (MBF) were calculated. Artifacts, image noise, and overall image quality were qualitatively assessed. Furthermore, the relation between signal intensity (SI) and contrast medium (CM) concentration was determined in phantoms. Using PAT the linear range of the SR-TrueFISP sequence was increased about 40%. All three PAT methods introduced significant loss in SNR and CNR. GRAPPA yielded slightly better values then mSENSE and TSENSE. Both SENSE techniques introduced significantly residual aliasing artifacts. Image noise was increased with all three PAT methods. However, overall image quality was reduced only with mSENSE. Even though GRAPPA yielded smaller NUS values than non-PAT, mSENSE, and TSENSE, no differences were found in MBF between all applied techniques. Quantitative and semiquantitative myocardial perfusion imaging can benefit from PAT due to shorter acquisition times and increased linearity of the pulse sequence. GRAPPA and TSENSE turned out to be well suited for quantitative myocardial perfusion imaging.Journal of Magnetic Resonance Imaging 08/2008; 28(1):51-9. · 2.70 Impact Factor -
Article: Assessment of thoracic aortic dimensions in an experimental setting: comparison of different unenhanced magnetic resonance angiography techniques with electrocardiogram-gated computed tomography angiography for possible application in the pediatric population.
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ABSTRACT: To compare different unenhanced magnetic resonance angiography (MRA) techniques for quantitative evaluation of vessel lumen in an experimental setting in young pigs whose dimensions allow for a comparison with a pediatric population. Magnetic resonance imaging was performed in 5 healthy ventilated pigs at 1.5 T. Three different electrocardiogram (ECG)-triggered sequences were applied for MRA: [TSE-Db] T2-weighted dark-blood TurboSpinEcho (2.0 x 1.1 x 4 mm3); [trueFISP] 2D-steady-state-free-precession (2.2 x 1.8 x 2 mm3); [NAV] respiratory-gated, T2-prepared 3D-trueFISP (1.3 x 1.3 x 1.3 mm3). ECG-gated-CT angiography (CTA) (16-row CT, 1 mm collimation) served as the standard of reference. The vessel lumen was measured at 7 positions perpendicularly angulated to the vessel wall on multiplanar reformations: ascending aorta (P1), the aortic arch before (P2) and after (P3) the origin of the first supraaortic branch, the aortic arch after the origin of the second supraaortic branch (P4), the descending aorta at the level of the diaphragm (P5), and the first and second supraaortic branches (P6, P7). Percentage differences in the vessel area determined by MRA reformation compared with CTA-reformation were 10% +/- 20% and 35% +/- 27% (TSE-Db), -4% +/- 13% and 20% +/- 24% (trueFISP), and -3% +/- 13% and -10% +/- 19% (NAV), for positions P1 to P5 and P6 to P7, respectively. A significant difference from CTA was found for TSE-Db at all positions, and for trueFISP only at positions P6 and P7. Unenhanced MRA techniques allow for a reliable assessment of the dimensions of the thoracic aorta compared with CTA as the standard of reference. Using ECG-gating and navigator techniques, the free-breathing approach showed the best agreement with CTA. This technique may therefore be the most useful in the pediatric age group allowing for true 3D data acquisition with its inherent postprocessing possibilities.Investigative Radiology 04/2008; 43(3):179-86. · 4.59 Impact Factor -
Article: MR angiography of the pedal arteries with gadobenate dimeglumine, a contrast agent with increased relaxivity, and comparison with selective intraarterial DSA.
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ABSTRACT: To compare gadobenate dimeglumine (Gd-BOPTA)-enhanced MR angiography (i.e., contrast-enhanced MRA [CE-MRA]) of the pedal vasculature with selective digital subtraction angiography (DSA) in patients with peripheral arterial occlusive disease (PAOD). A total of 22 patients with PAOD were prospectively examined at 1.5T. For contrast enhancement, 0.1 mmol/kg body weight of Gd-BOPTA were applied. MRA consisted of dynamic imaging with acquisition of six consecutive data sets. Acquisition time for each data set was 24 seconds, voxel size was 1.0 x 1.0 x 1.3 mm(3). A total of 20 out of 22 patient underwent selective DSA, two patients fine-needle DSA. DSA and MRA were performed within seven days. Image analysis was independently done by two observers with assessment of overall image quality, motion artifacts, detection of patent vessel segments of the distal calf and pedal vessels, and the number of patent metatarsal arteries. After four weeks, a consensus reading of DSA images was done. A second consensus reading of CE-MRA was performed after a further six weeks. Consensus readings of MRA and DSA revealed higher image quality and fewer motion artifacts for MRA (P = 0.021 and P = 0.008, respectively, sign test); interobserver agreement was good (kappa = 0.78) for image quality, and moderate (kappa = 0.46) for motion artifacts. There were no differences between CE-MRA and DSA in detecting patent vessel segments with a high degree of agreement (kappa = 0.89), and interobserver agreement for MRA was substantial (kappa = 0.89). Significantly more vessels were assessed as partially occluded on DSA than on CE-MRA (P = 0.004). There was a good agreement between DSA and CE-MRA for assessment of relevant vessel stenosis (kappa = 0.61); interobserver agreement for MRA was good (kappa = 0.65). CE-MRA detected significantly more patent metatarsal arteries than did DSA (P < 0.001). Gd-BOPTA-enhanced MRA is comparable to DSA for assessment of the pedal vasculature, and is able to delineate significantly more patent vessels without segmental occlusions and more metatarsal arteries than selective DSA.Journal of Magnetic Resonance Imaging 01/2008; 27(1):78-85. · 2.70 Impact Factor -
Article: MultiHance-enhanced MR angiography of the peripheral run-off vessels in patients with diabetes.
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ABSTRACT: Foot complications associated with diabetes are the most common cause of nontraumatic lower extremity amputations in the industrialized world. Advances in surgical revascularization techniques in patients with lower limb ischemia require precise preoperative imaging of the peripheral vessels with the ultimate aim of reducing the rate of major foot amputations in these patients. MultiHance-enhanced 3-D MR angiography has been shown to provide better vascular contrast enhancement and better vessel delineation than conventional gadolinium agents at equivalent dose. Moreover, MultiHance-enhanced MR angiography results in significant increases in sensitivity and specificity over unenhanced MR angiography when compared with intraarterial digital subtraction angiography as the reference standard. Specifically, the greatest benefit of MultiHance is noted in the smaller more distal vessels of the lower leg. This is of utmost importance in diabetic patients as the presence of a patent distal calf or pedal vessel enables distal bypass grafting, and thus may significantly change treatment planning. The optimal approach for delineating the peripheral vasculature seems to be the application of a hybrid dual bolus approach in which cruropedal arteries are acquired first using sagittal slabs and a time-resolved acquisition technique. This allows the calf and pedal arteries to become assessable in a continuous way and partial volume artifacts to be decreased in the slice direction. This is followed by a two- or three-station bolus chase MR angiography for assessment of the aortoiliac, femoropopliteal, and proximal calf vessels. Vessel imaging may be supplemented by imaging of soft tissues for delineation of associated inflammatory or necrotic complications in the diabetic foot.European Radiology 01/2008; 17 Suppl 6:F63-8. · 3.22 Impact Factor -
Article: Comparison of three accelerated pulse sequences for semiquantitative myocardial perfusion imaging using sensitivity encoding incorporating temporal filtering (TSENSE).
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ABSTRACT: To investigate the parallel acquisition technique sensitivity encoding incorporating temporal filtering (TSENSE) with three saturation-recovery (SR) prepared pulse sequences (SR turbo fast low-angle shot [SR-TurboFLASH], SR true fast imaging with steady precession [SR-TrueFISP], and SR-prepared segmented echo-planar-imaging [SR-segEPI]) for semiquantitative first-pass myocardial perfusion imaging. In blood- and tissue-equivalent phantoms the relationship between signal intensity (SI) and contrast-medium concentration was evaluated for the three pulse sequences. In volunteers, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and normalized upslopes (NUS) were calculated from signal-time curves (STC). Moreover, artifacts, image noise, and overall image quality were qualitatively evaluated. Phantom data showed a 40% increased linear range of the relation between SI and contrast-medium concentration with TSENSE. In volunteers, TSENSE introduced significantly residual artifacts and loss in SNR and CNR. No differences were found for NUS values with TSENSE. SR-TrueFISP yielded highest SNR, CNR, and quality scores. However, in SR-True-FISP images, dark-banding artifacts were most pronounced. NUS values obtained with SR-TrueFISP were significantly higher and with SR-segEPI significantly lower than with SR-TurboFLASH. Semiquantitative myocardial perfusion imaging can significantly benefit from TSENSE due to shorter acquisition times and increased linearity of the pulse sequences. Among the three pulse sequences tested, SR-TrueFISP yielded best image quality. SR-segEPI proved to be an interesting alternative due to shorter acquisition times, higher linearity and fewer dark-banding artifacts.Journal of Magnetic Resonance Imaging 10/2007; 26(3):569-79. · 2.70 Impact Factor -
Article: Chronic thromboembolic pulmonary hypertension - assessment by magnetic resonance imaging.
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ABSTRACT: Chronic thromboembolic pulmonary hypertension (CTEPH) is a severe disease that has been ignored for a long time. However, with the development of improved therapeutic modalities, cardiologists and thoracic surgeons have shown increasing interest in the diagnostic work-up of this entity. The diagnosis and management of chronic thromboembolic pulmonary hypertension require a multidisciplinary approach involving the specialties of pulmonary medicine, cardiology, radiology, anesthesiology and thoracic surgery. With this approach, pulmonary endarterectomy (PEA) can be performed with an acceptable mortality rate. This review article describes the developments in magnetic resonance (MR) imaging techniques for the diagnosis of chronic thromboembolic pulmonary hypertension. Techniques include contrast-enhanced MR angiography (ce-MRA), MR perfusion imaging, phase-contrast imaging of the great vessels, cine imaging of the heart and combined perfusion-ventilation MR imaging with hyperpolarized noble gases. It is anticipated that MR imaging will play a central role in the initial diagnosis and follow-up of patients with CTEPH.European Radiology 02/2007; 17(1):11-21. · 3.22 Impact Factor
Top co-authors
Top Journals
Institutions
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1998–2012
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Johannes Gutenberg-Universität Mainz
Mainz, Rhineland-Palatinate, Germany
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2011
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Universität Heidelberg
- Department of Diagnostic and Interventional Radiology
Heidelberg, Baden-Wuerttemberg, Germany
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2007
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Heidelberg University Hospital
Heidelberg, Baden-Wuerttemberg, Germany
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2004–2006
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Deutsches Krebsforschungszentrum
- Division of Radiology
Heidelberg, Baden-Wuerttemberg, Germany -
John Radcliffe Hospital
- Department of Cardiovascular Medicine
Oxford, ENG, United Kingdom
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