Georg Mühlenbruch

RWTH Aachen University, Aachen, North Rhine-Westphalia, Germany

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Publications (138)346.12 Total impact

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    ABSTRACT: Iodinated contrast media (CM) in computed tomographic angiography is characterized by its concentration and, consecutively, by its viscosity. Viscosity itself is directly influenced by temperature, which will furthermore affect injection pressure. Therefore, the purposes of this study were to systematically evaluate the viscosity of different CM at different temperatures and to assess their impact on injection pressure in a circulation phantom. Initially, viscosity of different contrast media concentrations (240, 300, 370, and 400 mgI/mL) was measured at different temperatures (20°C-40°C) with a commercially available viscosimeter. In the next step, a circulation phantom with physical conditions was used. Contrast media were prepared at different temperatures (20°C, 30°C, 37°C) and injected through a standard 18-gauge needle. All other relevant parameters were kept constant (iodine delivery rate, 1.9 g I/s; total amount of iodine, 15 g I). Peak flow rate (in milliliter per second) and injection pressure (psi) were monitored. Differences in significance were tested using the Kruskal-Wallis test (Statistical Package for the Social Sciences). Viscosities for iodinated CM of 240, 300, 370, and 400 mg I/mL at 20°C were 5.1, 9.1, 21.2, and 28.8 mPa.s, respectively, whereas, at 40°C, these were substantially lower (2.8, 4.4, 8.7, and 11.2 mPa.s). In the circulation phantom, mean (SD) peak pressures for CM of 240 mg I/mL at 20°C, 30°C, and 37°C were 107 (1.5), 95 (0.6), and 92 (2.1) psi; for CM of 300 mg I/mL, 119 (1.5), 104 (0.6), and 100 (3.6) psi; for CM of 370 mg I/mL, 150 (0.6), 133 (4.4), and 120 (3.5) psi; and for CM of 400 mg I/mL, 169 (1.0), 140 (2.1), and 135 (2.9) psi, respectively, with all P values less than 0.05. Low concentration, low viscosity, and high temperatures of CM are beneficial in terms of injection pressure. This should also be considered for individually tailored contrast protocols in daily routine scanning.
    Investigative radiology 01/2014; · 4.85 Impact Factor
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    ABSTRACT: Sclerostin is a Wnt pathway antagonist regulating osteoblast activity and bone turnover. Here, we assessed the potential association of sclerostin with the development of coronary artery (CAC) and aortic valve calcifications (AVC) in haemodialysis (HD) patients. We conducted a cross-sectional multi-slice computed tomography (MS-CT) scanning study in 67 chronic HD patients (59.4 +/- 14.8 yrs) for measurement of CAC and AVC. We tested established biomarkers as well as serum sclerostin (ELISA) regarding their association to the presence of calcification. Fifty-four adults without relevant renal disease served as controls for serum sclerostin levels. Additionally, sclerostin expression in explanted aortic valves from 15 dialysis patients was analysed ex vivo by immunohistochemistry and mRNA quantification (Qt-RT-PCR). CAC (Agatston score > 100) and any AVC were present in 65% and in 40% of the MS-CT patient group, respectively. Serum sclerostin levels (1.53 +/- 0.81 vs 0.76 +/- 0.31 ng/mL, p < 0.001) were significantly elevated in HD compared to controls and more so in HD patients with AVC versus those without AVC (1.78 +/- 0.84 vs 1.35 +/- 0.73 ng/mL, p = 0.02). Multivariable regression analysis for AVC revealed significant associations with higher serum sclerostin. Ex vivo analysis of uraemic calcified aortic valves (n = 10) revealed a strong sclerostin expression very close to calcified regions (no sclerostin staining in non-calcified valves). Correspondingly, we observed a highly significant upregulation of sclerostin mRNA in calcified valves compared to non-calcified control valves. We found a strong association of sclerostin with calcifying aortic heart valve disease in haemodialysis patients. Sclerostin is locally produced in aortic valve tissue adjacent to areas of calcification.
    BMC Nephrology 10/2013; 14(1):219. · 1.64 Impact Factor
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    ABSTRACT: Both iodine delivery rate (IDR) and iodine concentration are decisive factors for vascular enhancement in computed tomographic angiography. It is unclear, however, whether the use of high-iodine concentration contrast media is beneficial to lower iodine concentrations when IDR is kept identical. This study evaluates the effect of using different iodine concentrations on intravascular attenuation in a circulation phantom while maintaining a constant IDR. A circulation phantom with a low-pressure venous compartment and a high-pressure arterial compartment simulating physiological circulation parameters was used (heart rate, 60 beats per minute; stroke volume, 60 mL; blood pressure, 120/80 mm Hg). Maintaining a constant IDR (2.0 g/s) and a constant total iodine load (20 g), prewarmed (37°C) contrast media with differing iodine concentrations (240-400 mg/mL) were injected into the phantom using a double-headed power injector. Serial computed tomographic scans at the level of the ascending aorta (AA), the descending aorta (DA), and the left main coronary artery (LM) were obtained. Total amount of contrast volume (milliliters), iodine delivery (grams of iodine), peak flow rate (milliliter per second), and intravascular pressure (pounds per square inch) were monitored using a dedicated data acquisition program. Attenuation values in the AA, the DA, and the LM were constantly measured (Hounsfield unit [HU]). In addition, time-enhancement curves, aortic peak enhancement, and time to peak were determined. All contrast injection protocols resulted in similar attenuation values: the AA (516 [11] to 531 [37] HU), the DA (514 [17] to 531 [32] HU), and the LM (490 [10] to 507 [17] HU). No significant differences were found between the AA, the DA, and the LM for either peak enhancement (all P > 0.05) or mean time to peak (AA, 19.4 [0.58] to 20.1 [1.05] seconds; DA, 21.1 [1.0] to 21.4 [1.15] seconds; LM, 19.8 [0.58] to 20.1 [1.05] seconds). This phantom study demonstrates that constant injection parameters (IDR, overall iodine load) lead to robust enhancement patterns, regardless of the contrast material used. Higher iodine concentration itself does not lead to higher attenuation levels. These results may stimulate a shift in paradigm toward clinical usage of contrast media with lower iodine concentrations (eg, 240 mg iodine/mL) in individual tailored contrast protocols. The use of low-iodine concentration contrast media is desirable because of the lower viscosity and the resulting lower injection pressure.
    Investigative radiology 07/2013; · 4.85 Impact Factor
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    ABSTRACT: Objectives To investigate simultaneous dual-isotope SPECT/CT with two differently radioisotope-labelled albumin-microsphere fractions for treatment planning of hepatic radioembolisation. Methods In addition to 99mTechnetium-labelled albumin microspheres (commercially available), we performed labelling with 111Indium. Binding stability of 111Indium-labelled microspheres was tested in vitro and in vivo in mice. Simultaneous dual-isotope SPECT/CT imaging was validated in an anthropomorphic torso phantom; subsequently, dual-isotope SPECT/CT was performed under in-vivo conditions in pigs (n = 3) that underwent transarterial injection of 99mTechnetium- and 111Indium-labelled microspheres in the liver (right and left hepatic artery, respectively), in both kidneys and in the gluteal musculature. In total, n = 18 transarterial injections were performed. Results In-vitro testing and in-vivo studies in mice documented high binding stability for both 99mTechnetium-labelled and 111Indium-labelled microsphere fractions. In phantom studies, simultaneous dual-isotope SPECT/CT enabled reliable separation of both isotopes. In pigs, the identified deposition of both isotopes could be accurately matched with intended injection targets (100 %, 18/18 intended injection sites). Furthermore, an incidental deposition of 99mTechnetium-labelled microspheres in the stomach could be correlated to the test injection into a right hepatic artery. Conclusion Simultaneous dual-isotope SPECT/CT after transarterial injection with 99mTechnetium- and 111Indium-labelled microspheres is feasible. Thus, it may offer additional, valuable information compared to single 99mTechnetium-labelled albumin examinations. Key Points • Simultaneous dual-isotope SPECT/CT with 111 In- and 99m Tc-labelled albumin microspheres is feasible. • Differentiation of two microsphere fractions after transarterial injection is possible. • The origin of an extra-hepatic microsphere deposition can be correlated to the corresponding artery. • This technique could reduce the setup time for selective internal radiation treatment.
    European Radiology 06/2013; · 4.34 Impact Factor
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    ABSTRACT: PURPOSE: Ruptured cerebral arterial aneurysms require prompt treatment by either surgical clipping or endovascular coiling. Training for these sophisticated endovascular procedures is essential and ideally performed in animals before their use in humans. Simulators and established animal models have shown drawbacks with respect to degree of reality, size of the animal model and aneurysm, or time and effort needed for aneurysm creation. We therefore aimed to establish a realistic and readily available aneurysm model. MATERIALS AND METHODS: Five anticoagulated domestic pigs underwent endovascular intervention through right femoral access. A total of 12 broad-neck aneurysms were created in the carotid, subclavian, and renal arteries using the Amplatzer vascular plug. RESULTS: With dedicated vessel selection, cubic, tubular, and side-branch aneurysms could be created. Three of the 12 implanted occluders, two of them implanted over a side branch of the main vessel, did not induce complete vessel occlusion. However, all aneurysms remained free of intraluminal thrombus formation and were available for embolization training during a surveillance period of 6 h. Two aneurysms underwent successful exemplary treatment: one was stent-assisted, and one was performed with conventional endovascular coil embolization. CONCLUSION: The new porcine aneurysm model proved to be a straightforward approach that offers a wide range of training and scientific applications that might help further improve endovascular coil embolization therapy in patients with cerebral aneurysms.
    CardioVascular and Interventional Radiology 06/2012; · 2.09 Impact Factor
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    ABSTRACT: To implement a retrospective intrinsic landmark-based (ILB) gating protocol for contrast-enhanced ultrasound (CEUS) and to compare its efficiency to non-gated, manually gated and extrinsically gated CEUS. CEUS of the liver was performed in healthy mice (n = 5) and in NEMO knockout mice with dysplastic livers (n = 5). In healthy animals, first-pass kinetics of non-specific microbubbles was recorded. Knockout mice were analysed regarding retention of VEGFR2-specific microbubbles. For retrospective gating, a landmark which showed respiratory movement was encircled as a region of interest (ROI). During inspiration, the signal intensity within the ROI altered, which served as gating signal. To evaluate the accuracy, non-gated, extrinsically gated and ILB-gated time-intensity curves were created. For each curve, descriptive parameters were calculated and compared to the gold standard (manual frame-by-frame gating). No significant differences in the variation of ILB- and extrinsically gated time-intensity curves from the gold standard were observed. Non-gated data showed significantly higher variations. Also the variation of molecular ultrasound data was significantly lower for ILB-gated compared to non-gated data. ILB gating is a robust and easy method to improve data accuracy in functional and molecular ultrasound liver imaging. This technique can presumably be translated to contrast-enhanced ultrasound examinations in humans. • Quantitative analysis of the uptake of contrast agents during ultrasound is complex. • Intrinsic landmark-based gating (ILB) offers a simple implementable method for motion correction. • Results using ILB-gating are comparable to extrinsic gating using external biomonitoring devices. • Functional and molecular imaging of mobile organs will benefit from ILB gating.
    European Radiology 03/2012; 22(8):1789-96. · 4.34 Impact Factor
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    ABSTRACT: To develop and evaluate a user-friendly tool to enable efficient, accurate, and reproducible quantification of blood vessel stenosis in computed tomographic (CT) and magnetic resonance (MR) angiographic data sets. All clinical experiments were approved by the institutional review board, and informed patient consent was acquired. Animal experiments were approved by the governmental review committee on animal care. A virtual elastic sphere passes through a blood vessel specified by user-provided start and end points, and the adapting diameter over the course of the vessel is recorded. The program was tested in phantoms to determine the accuracy of diameter estimation, and it was applied in micro-CT data sets of mice with induced vessel stenosis. Dual-energy CT angiography and MR angiography were performed in 16 patients with carotid artery stenosis, and reproducibility and required reader time of this automated technique were compared with manual measurements. Additionally, the effect of dual-energy CT-based discrimination between iodine- and calcium-based enhancement was investigated. Differences between carotid artery diameters of mice and between automated and manual measurement durations were assessed with a paired t test. Reproducibility of stenosis scores was evaluated with the Fisher z test. Phantom diameters were determined with an average error of 0.094 mm. Diameters of normal and injured carotid arteries of mice were significantly different (P < .01). For patient data, automated interreader variability was significantly (P < .01) lower than manual intra- and interreader variability, while time efficiency was improved (P < .01). The virtual elastic sphere tool is applicable to CT, dual-energy CT, and MR angiography, and it improves reproducibility and efficiency over that achieved with manual stenosis measurements.
    Radiology 09/2011; 260(3):709-17. · 6.34 Impact Factor
  • M Palmowski, G Mühlenbruch, C Grouls, R W Günther
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    ABSTRACT: In Conn's syndrome, adrenal vein sampling (AVS) is used to secure the site of hormonal overproduction. The left adrenal vein is usually easy to explore, the right is difficult. Examination requires several differently configured catheters. Here, we introduce a new technique for AVS using a single cobra catheter, which was tested in n = 13 patients. In an inverted configuration, the cobra catheter can be used to explore the left side, while the regular configuration can be used for the right side. The technical details are described in the manuscript. In all patients, left AVS could be performed successfully using the inverted catheter configuration. In n = 11 patients, right AVS was carried out successfully with a cobra catheter in regular configuration. In two cases, a Sidewinder-I catheter was required due to a steep angle of the adrenal vein.
    RöFo - Fortschritte auf dem Gebiet der R 02/2011; 183(2):167-70. · 2.76 Impact Factor
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    ABSTRACT: Significant extracranial stenosis of the ICA is a known risk factor for future stroke and it has been shown that revascularization reduces the risk of future stroke. We applied BOLD fMRI in patients with carotid artery stenosis before and after CEA. Our purpose was to determine whether fMRI is able to demonstrate impaired CVR and to identify patient parameters that are associated with postoperative changes of cerebral hemodynamics. Nineteen consecutive patients with symptomatic (n = 13) and asymptomatic (n = 6) stenosis of the ICA were prospectively recruited (male/female ratio = 16:3; age, 69 ± 8,1 years). fMRI using a simple bilateral motor task was performed immediately before and after CEA. Mean BOLD MSC was significantly increased postoperatively (MSC, 0.13 ± 0.66; P = 0.0002). Patients with a stenosis of <80% demonstrated an increase in MSC (MSC, 0.32 ± 0.59; P ≤ .0001). Patients with previous ischemic stroke showed a larger MSC than patients with TIAs (stroke: MSC, 0.55 ± 0.65; P ≤ .0001; TIA: MSC, 0.05 ± 0.26; P = 0.054). Patients older than 70 years had a significantly larger MSC following surgery (≤70 years: MSC, -0.01 ± 0.39; P = .429; >70 years: MSC, 0.29 ± 0.48; P ≤ .0001). BOLD fMRI can demonstrate changes in cerebral hemodynamics before and after CEA, indicative of an ameliorated CVR. This response is dependent on the age of the patient, the degree of preoperative stenosis, and the patient's symptoms.
    American Journal of Neuroradiology 11/2010; 31(10):1791-8. · 3.17 Impact Factor
  • Georg Mühlenbruch, Timo Krings
    European Radiology 04/2010; · 4.34 Impact Factor
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    ABSTRACT: Cardiac resynchronization therapy (CRT) provides a therapeutic option for patients with congestive heart failure (CHF). There is evidence that the optimal pacing site (OIS) is vicinal to the region of the latest contraction (RLC). However, the RLC is not identified routinely to guide lead implantation to the coronary venous system (CVS). The aim of this study was: (i) to develop a software over-imposing CVS-anatomy on parametric images of left ventricular dyssynchrony in a 3D-format obtained from computed tomography (CT) and cardiac magnetic resonance imaging (MRI); and (ii) to apply this 3D-software for analysing the possible correlation between functional/ clinical improvement and the distance between final implantation site (FIS) and RLC. In 20 CHF-patients (11 men, 65.6 +/- 6.8 y, ejection fraction (EF): 27.5 +/- 6.1%) CRT-leads were implanted; follow-up included echocardiographic and exercise evaluation. The OIS and the FIS were noted on 3D-registrations and the distances OIS-RLC and FIS-RLC measured.The target vessel was reached in 14 cases. NYHA class and EF improved significantly with a low rate of non-responders of 3 (15%) (EF) and 4 (20%) (NYHA). Image registration was possible in all patients. Post-process 3D-analysis revealed no correlation between the distance FIS-RLC and functional or echocardiographic improvements.There was a trend towards a shorter distance FIS-RLC in patients classified as responders (EF). NYHA class improved significantly better in patients with target vessel implantation. Registration of CT/MRI-images enables efforts to reach the RLC by preoperative identification of corresponding veins. Larger randomized trials must define the definite therapeutic benefit.
    Acta cardiologica 04/2010; 65(2):161-70. · 0.61 Impact Factor
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    ABSTRACT: Der mit Symptomen verbundene Kollaps des wahren thorakalen Lumens durch einen komprimierenden thrombosierten Falschkanal ist Der mit Symptomen verbundene Kollaps des wahren thorakalen Lumens durch einen komprimierenden thrombosierten Falschkanal ist eine seltene Morphologie der Typ-B-Dissektion. Der Kollaps kann mit einer vital bedrohenden Organmalperfusion oder peripheren eine seltene Morphologie der Typ-B-Dissektion. Der Kollaps kann mit einer vital bedrohenden Organmalperfusion oder peripheren Extremitätenischämie assoziiert sein. Wir berichten über eine erfolgreiche endovaskuläre Behandlung eines „true lumen collapse“ Extremitätenischämie assoziiert sein. Wir berichten über eine erfolgreiche endovaskuläre Behandlung eines „true lumen collapse“ bei einer 65-jährigen Patientin, die mit akuter Paraparese beider Beine und einem akuten Nierenversagen 5Wochen nach dem bei einer 65-jährigen Patientin, die mit akuter Paraparese beider Beine und einem akuten Nierenversagen 5Wochen nach dem Initialereignis zur Aufnahme kam. Der Kollaps des wahren Lumens wurde durch eine extensive Thrombosierung des Falschkanals Initialereignis zur Aufnahme kam. Der Kollaps des wahren Lumens wurde durch eine extensive Thrombosierung des Falschkanals bei fehlendem „reentry“ verursacht. bei fehlendem „reentry“ verursacht. A symptomatic true lumen collapse within the descending aorta due to extensive false lumen thrombosis is a rare morphology A symptomatic true lumen collapse within the descending aorta due to extensive false lumen thrombosis is a rare morphology in type B dissection. Because of organ malperfusion, it represents a life-threatening situation. Here we present successful in type B dissection. Because of organ malperfusion, it represents a life-threatening situation. Here we present successful management of a symptomatic true lumen collapse in a 65-year-old patient. She suffered from sudden paraparesis in both legs management of a symptomatic true lumen collapse in a 65-year-old patient. She suffered from sudden paraparesis in both legs combined with acute renal failure 5 weeks after acute type B dissection and underwent thoracic stent grafting in an emergency combined with acute renal failure 5 weeks after acute type B dissection and underwent thoracic stent grafting in an emergency setting. The true lumen collapse was caused by extensive thrombosis of the false lumen in combination with the absence of setting. The true lumen collapse was caused by extensive thrombosis of the false lumen in combination with the absence of a distal reentry point. a distal reentry point. SchlüsselwörterTyp-B-Aortendissektion-Kollaps wahres Lumen-Organmalperfusion-Akutes Nierenversagen-Thorakaler Stentgraft SchlüsselwörterTyp-B-Aortendissektion-Kollaps wahres Lumen-Organmalperfusion-Akutes Nierenversagen-Thorakaler Stentgraft KeywordsType B dissection-True lumen collapse-Organ malperfusion-Renal failure-TEVAR KeywordsType B dissection-True lumen collapse-Organ malperfusion-Renal failure-TEVAR
    Gefässchirurgie 01/2010; 15(1):38-42. · 0.24 Impact Factor
  • Rofo-fortschritte Auf Dem Gebiet Der Rontgenstrahlen Und Der Bildgebenden Verfahren - ROFO-FORTSCHR RONTGENSTRAHL. 01/2010; 182.
  • M. Palmowski, G. Mühlenbruch, C. Grouls, R. Günther
    Rofo-fortschritte Auf Dem Gebiet Der Rontgenstrahlen Und Der Bildgebenden Verfahren - ROFO-FORTSCHR RONTGENSTRAHL. 01/2010; 182(08).
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    ABSTRACT: An estimated 75–80% of inguinal hernia operations involve placing a mesh prosthesis, either laparoscopically or using an open technique, to patch the defect in the floor of the inguinal canal. Foreign body reactions, with fibroblastic ingrowth and chronic inflammation, are believed to reinforce the abdominal wall and decrease the risk of recurrence. It has been proven that this foreign body reaction is proportionate to the weight, structure, and polymer of the mesh and that commonly used meshes contain too much material, producing an exaggerated foreign body reaction/tissue response and leading to clinical complications [1–3]. To minimize the foreign body reaction and clinical complications, new types of mesh materials have been introduced that have a decreased amount of material and larger pores, resulting in a nearby physiologic tissue ingrowth [2, 4, 5]. Further improvement of biocompatibility has been achieved using polyvinylidene fluoride (PVDF) as the polymer [3].
    12/2009: pages 21-28;
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    ABSTRACT: We report the case of a man with an uncommon anomaly of the origin and course of the left coronary artery. Clinical, coronary angiography, magnetic resonance imaging, and multislice computed tomography findings of this intermittently symptomatic 49 year-old patient with the rare anomaly of his left coronary artery stemming from the right sinus of Valsalva and taking an interarterial and intraseptal course are presented. The diagnostic value of the different imaging modalities is discussed.
    CardioVascular and Interventional Radiology 09/2009; 33(2):389-93. · 2.09 Impact Factor
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    ABSTRACT: To assess global and regional ventricular function in the presence of myocardial infarction (MI) using cardiac dual-source computed tomography (DSCT) in comparison to magnetic resonance (MR) imaging. Fourteen pigs (58.6 ± 8.9 kg) were included in this study. In seven animals acute MI was induced by temporary balloon occlusion of the left circumflex artery. Thereafter, DSCT and MR imaging were performed with standardized examination protocols. Left (LV) and right ventricular (RV) volumes, ejection fraction (EF), peak filling rate (PFR), and peak ejection rate (PER) as well as LV myocardial mass were calculated. LV wall motion was visually assessed from cine loops. Data was analyzed using Bland-Altman plots, Lin's concordance-correlation coefficient (ρ(c)) and weighted kappa statistics. Ventricular volumes and mass as determined by DSCT correlated well with MR imaging. Mean LV-EF was 49.4 ± 16.5% on DSCT and 50.0 ± 16.1% on MR imaging (ρ(c) = 0.9928). The corresponding mean RV-EF results were 45.9 ± 10.6% and 45.8 ± 10.6% (ρ(c) = 0.9969), respectively. Bland-Altman plots revealed no systematic errors, but PER and PFR showed a relevant scattering. Regional wall motion scores agreed in 216/224 myocardial segments (κ = 0.925). DSCT permits the reliable assessment of global and regional function in healthy and infarcted myocardium, but is not yet suited for the assessment of dynamic functional parameters like PER and PFR.
    European journal of radiology 09/2009; 77(3):443-9. · 2.65 Impact Factor
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    ABSTRACT: To intraindividually compare magnetic resonance (MR) imaging, ECG-gated multi-detector spiral computed tomography (MDCT) and gated single photon emission computed tomography (SPECT) for the evaluation of global and regional myocardial function and the identification of myocardial perfusion abnormalities. Nine patients (8 men; 55.1+/-8.9 years) with a history of myocardial infarction (MI) were included in this retrospective study. All patients had undergone segmented k-space steady state free precession MR imaging, (99m)Tc-MIBI gated myocardial perfusion SPECT and contrast enhanced ECG-gated 16-MDCT. Ventricular volumes and ejection fraction (EF) were calculated. Left ventricular (LV) wall motion at rest was analyzed. For SPECT and arterial phase MDCT perfusion abnormalities were assessed. Data was compared with Lin's concordance-correlation coefficient (rho(c)), Bland-Altman plots and kappa statistics. For EF, there was an excellent concordance and correlation (rho(c)=0.99) between SPECT (EF=41.7+/-10.4%), MDCT (EF=42.2+/-11.1%), and MR imaging (EF=41.9+/-11.4%). Considering MR imaging as standard of reference, MDCT (kappa=0.86) is superior to SPECT (kappa=0.51) for the assessment of the regional wall motion at rest. There was a good agreement between SPECT and MDCT regarding the detection of perfusion abnormalities (kappa=0.62). MDCT, MR imaging, and SPECT allow for the reliable assessment of global and regional left ventricular function in patients with a history of MI. MDCT also allows to some extent for the detection of perfusion abnormalities. With its potential to assess both, the coronary arteries as well as the myocardium, MDCT a promising modality for the comprehensive diagnostic work-up in patients with suspected myocardial ischemia.
    European journal of radiology 09/2009; 71(3):480-5. · 2.65 Impact Factor
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    ABSTRACT: Since semi-automated lesion quantification may be more precise than manual uni- and bidimensional measurements, the purpose of this study was to compare semi-automated with manual evaluations of cervical, thoracic and abdominal lymph nodes in patients with malignant lymphoma. 62 patients with known malignant lymphoma underwent staging with contrast-enhanced 16-MDCT (16x0.7 mm coll., 120 kV, cervical/thoracic/abdominal: 150/120/160 mAseff., 1/1.25 /1 pitch, 4/3 - 5/4 - 5/4 slice thickness/reconstruction increment). On the basis of these standard reconstructed slices, each lesion was quantified in terms of RECIST and its longest orthographic diameter using a semi-automated software tool (Syngo CT Oncology, Siemens Medical Solutions, Forchheim, Germany) and manually by an experienced radiologist. The degree of agreement between manual measurements and software quantification was statistically assessed by computing the concordance correlation coefficient kappa and represented graphically in corresponding Bland-Altman plots. 74/80 cervical, 51/80 thoracic and 75/80 abdominal lymph nodes were correctly evaluated by the software. A strong degree of agreement between both measurement techniques (RECIST diameter: kappa = 0.97 (cervical)/0.98 (thoracic)/0.99 (abdominal); longest orthographic diameter: kappa = 0.97/0.93/0.97) was obtained. Semi-automated measurement of cervical, thoracic and abdominal lymph nodes showed valid results on standard axial reconstructions compared to manual quantification with the limitation of a high false segmentation rate in thoracic lymph nodes.
    RöFo - Fortschritte auf dem Gebiet der R 08/2009; 181(9):888-95. · 2.76 Impact Factor
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    ABSTRACT: The purpose of this study was to investigate differences in change of size and CT value between local recurrences and tumor-free areas after CT-guided radiofrequency ablation (RFA) of hepatic metastases during follow-up by means of dedicated software for automatic evaluation of hepatic lesions. Thirty-two patients with 54 liver metastases from breast or colorectal cancer underwent triphasic contrast-enhanced multidetector-row computed tomography (MDCT) to evaluate hepatic metastatic spread and localization before CT-guided RFA and for follow-up after intervention. Sixteen of these patients (65.1 + or - 10.3 years) with 30 metastases stayed tumor-free (group 1), while the other group (n = 16 with 24 metastases; 62.0 + or - 13.8 years) suffered from local recurrent disease (group 2). Applying an automated software tool (SyngoCT Oncology; Siemens Healthcare, Forchheim, Germany), size parameters (volume, RECIST, WHO) and attenuation were measured within the lesions before, 1 day after, and 28 days after RFA treatment. The natural logarithm (ln) of the quotient of the volume 1 day versus 28 days after RFA treament was computed: lnQ1//28/0(volume). Analogously, ln ratios of RECIST, WHO, and attenuation were computed and statistically evaluated by repeated-measures ANOVA. One lesion in group 2 was excluded from further evaluation due to automated missegmentation. Statistically significant differences between the two groups were observed with respect to initial volume, RECIST, and WHO (p < 0.05). Furthermore, ln ratios corresponding to volume, RECIST, and WHO differed significantly between the two groups. Attenuation evaluations showed no significant differences, but there was a trend toward attenuation assessment for the parameter lnQ28/0(attenuation) (p = 0.0527), showing higher values for group 1 (-0.4 + or - 0.3) compared to group 2 (-0.2 + or - 0.2). In conclusion, hepatic metastases and their zone of coagulation necrosis after RFA differed significantly between tumor-free and local-recurrent ablation zones with respect to the corresponding size parameters. A new parameter (lnQ1//28/0(volume/RECIST/WHO/attenuation)) was introduced, which appears to be of prognostic value at early follow-up CT.
    CardioVascular and Interventional Radiology 08/2009; 33(2):297-306. · 2.09 Impact Factor

Publication Stats

1k Citations
346.12 Total Impact Points

Institutions

  • 2004–2011
    • RWTH Aachen University
      • • Department of Diagnostic and Interventional Radiology
      • • Neurologische Klinik
      • • Institut für Angewandte Medizintechnik
      • • Institut für Medizinische Statistik
      Aachen, North Rhine-Westphalia, Germany
  • 2005–2009
    • University Hospital RWTH Aachen
      • Department of Neurology
      Aachen, North Rhine-Westphalia, Germany