Konstantin Nikolaou
Research interests
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InterestsMRI, Computed Tomography, PET/CT, Molecular Imaging
Publications
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4.85Impact points
Diagnostic Accuracy of Dynamic Computed Tomographic Angiographic of the Lower Leg in Patients With Critical Limb Ischemia.
Investigative radiology. 04/2012;
OBJECTIVE: The purpose of this study was to assess the diagnostic accuracy of dynamic computed tomographic angiography (dyn-CTA) in patients with critical lower leg ischemia. MATERIALS AND METHODS: A population of 29 patients with known peripheral arterial occlusive disease (Fontaine stage III or IV... [more] OBJECTIVE: The purpose of this study was to assess the diagnostic accuracy of dynamic computed tomographic angiography (dyn-CTA) in patients with critical lower leg ischemia. MATERIALS AND METHODS: A population of 29 patients with known peripheral arterial occlusive disease (Fontaine stage III or IV) was examined with a combined CTA protocol consisting of a standard CTA (s-CTA) of the lower leg runoff from the diaphragm to the toes and dyn-CTA of the calves (scan range, 48 cm; 8 phases; 3.5 seconds per phase, 100 kV; 120 mAs; contrast volume, 50 mL; flow rate, 5.0 mL/s). Digital subtraction angiography was performed on all patients and served as a reference standard. For each of seven lower leg artery segments, arterial contrast and diagnostic confidence for stenosis assessment (3-point scale) were tested for s-CTA and dyn-CTA. Similarly, stenoses of calf-segments were classified on a 3-point scale separately for s-CTA and dyn-CTA and were compared with digital subtraction angiography to assess diagnostic accuracy. RESULTS: Compared with s-CTA, dyn-CTA resulted in significantly higher arterial contrast enhancement (68% vs 46% optimal contrast; P < 0.01) and higher diagnostic confidence (64% vs 48% fully confident, respectively, P < 0.05). Dyn-CTA had a slightly higher sensitivity for the detection of significant stenosis (98.0% vs 96.6%), and for the detection of occlusion (95.4% vs 94.4%). Specificity for dyn-CTA was higher than for s-CTA, both for detection of stenosis (97.1% vs 92.2%) and especially for the detection of vessel occlusions (99.3% vs 94.4%; P < 0.05). CONCLUSIONS: Compared with s-CTA, dyn-CTA provides improved arterial contrast enhancement, higher diagnostic confidence, and increased diagnostic accuracy for the detection of stenoses and occlusions in peripheral arterial occlusive disease patients.
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14.29Impact points
Prevalence of nonstenosing, complicated atherosclerotic plaques in cryptogenic stroke.
JACC. Cardiovascular imaging. 04/2012; 5(4):397-405.
Our goal was to assess the prevalence of complicated American Heart Association (AHA) lesion type VI plaques in the carotid arteries of patients with cryptogenic stroke. In up to 40% of ischemic stroke patients, no definite cause can be established despite extensive workup (i.e., cryptogenic stroke)... [more] Our goal was to assess the prevalence of complicated American Heart Association (AHA) lesion type VI plaques in the carotid arteries of patients with cryptogenic stroke. In up to 40% of ischemic stroke patients, no definite cause can be established despite extensive workup (i.e., cryptogenic stroke). To test the hypothesis if nonstenosing complicated carotid plaques may be the underlying etiology in some of these patients, we used high-resolution black-blood carotid magnetic resonance imaging (MRI), which can quantitatively assess plaque composition and morphology with good correlation to histopathology. Specifically, we focused on AHA type VI plaques, which are characterized by hemorrhage, thrombus, or fibrous cap rupture. Thirty-two consecutive patients (22 male; mean age 71.7 ± 11.9 years) with cryptogenic stroke and nonstenosing (<50%) eccentric carotid plaques were recruited from a single stroke unit. All patients underwent extensive clinical workup (brain MRI, duplex sonography, electrocardiography and Holter monitoring, transthoracic and transesophageal echocardiography, and laboratory investigations) to exclude other causes of stroke. All patients received a black-blood carotid MRI at 3-T with fat-saturated pre- and post-contrast T-1-, proton density-, and T-2-weighted and time-of-flight images using surface coils and parallel imaging techniques. Prevalence of AHA type VI plaque was determined in both carotid arteries on the basis of previously published MRI criteria. AHA type VI plaques were found in 12 of 32 arteries (37.5%) ipsilateral to the stroke, whereas there were no AHA type VI plaques contralateral to the stroke (p = 0.001). The most common diagnostic feature of AHA type VI plaques was intraplaque hemorrhage (75%), followed by fibrous plaque rupture (50%) and luminal thrombus (33%). This pilot study suggests that arterio-arterial embolism from complicated, nonstenosing carotid atherosclerotic plaques may play a role in a subgroup of patients previously diagnosed with cryptogenic stroke. To further evaluate the significance of AHA type VI plaques in cryptogenic stroke, future studies will have to analyze both clinical and imaging follow-up data, including event rates for secondary strokes.
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2.65Impact points
Time-resolved CT angiography in aortic dissection.
European journal of radiology. 03/2012;
OBJECTIVES: We performed this study to assess feasibility and additional diagnostic value of time-resolved CT angiography of the entire aorta in patients with aortic dissection. MATERIALS AND METHODS: 14 consecutive patients with known or suspected aortic dissection (aged 60±9 years) referred for ao... [more] OBJECTIVES: We performed this study to assess feasibility and additional diagnostic value of time-resolved CT angiography of the entire aorta in patients with aortic dissection. MATERIALS AND METHODS: 14 consecutive patients with known or suspected aortic dissection (aged 60±9 years) referred for aortic CT angiography were scanned on a dual-source CT scanner (Somatom Definition Flash; Siemens, Forchheim, Germany) using a shuttle mode for multiphasic image acquisition (range 48cm, time resolution 6s, 6 phases, 100kV, 110mAs/rot). Effective radiation doses were calculated from recorded dose length products. For all phases, CT densities were measured in the aortic lumen and renal parenchyma. From the multiphasic data, 3 phases corresponding to a triphasic standard CT protocol, served as a reference and were compared against findings from the time-resolved datasets. RESULTS: Mean effective radiation dose was 27.7±3.5mSv. CT density of the true lumen peaked at 355±53HU. Compared to the simulated triphasic protocol, time-resolved CT angiography added diagnostic information regarding a number of important findings: the enhancement delay between true and false lumen (n=14); the degree of membrane oscillation (n=14); the perfusion delay in arteries originating from the false lumen (n=9). Other additional information included true lumen collapse (n=4), quantitative assessment of renal perfusion asymmetry (n=2), and dynamic occlusion of aortic branches (n=2). In 3/14 patients (21%), these additional findings of the multiphasic protocol altered patient management. CONCLUSIONS: Multiphasic, time-resolved CT angiography covering the entire aorta is feasible at a reasonable effective radiation dose and adds significant diagnostic information with therapeutic consequences in patients with aortic dissection.
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2.95Impact points
Perfusion MRI for monitoring the effect of sorafenib on experimental prostate carcinoma: a validation study.
AJR. American journal of roentgenology. 02/2012; 198(2):384-91.
The purpose of this study was to investigate with immunohistochemical validation whether dynamic contrast-enhanced MRI with small-molecule contrast medium is useful for monitoring the effects of the multikinase inhibitor sorafenib on prostate carcinomas in rats. Copenhagen rats (n = 20) into which p... [more] The purpose of this study was to investigate with immunohistochemical validation whether dynamic contrast-enhanced MRI with small-molecule contrast medium is useful for monitoring the effects of the multikinase inhibitor sorafenib on prostate carcinomas in rats. Copenhagen rats (n = 20) into which prostate carcinoma (MAT-Ly-Lu-B2) had been implanted subcutaneously were imaged on the day of implantation and 7 days later with 3-T dynamic gadobutrol-enhanced MRI. The therapy group (n = 10) received daily administration of 10 mg/kg body weight sorafenib. Quantitative measurements of tumor perfusion, tumor vascularity, and permeability-surface area product were calculated with a two-compartment model. Dynamic contrast-enhanced MRI values were correlated with immunohistochemical results for validation. Tumor perfusion in sorafenib-treated prostate carcinoma declined significantly from day 0 to day 7 (47.9 ± 36.8 mL/100 mL/min to 24.4 ± 18.6 mL/100 mL/min; p < 0.05). No significant effect on permeability-surface area product was observed in either the therapy or the control group (p > 0.05). Tumor vascularity decreased significantly (p < 0.05) from day 0 to day 7 under sorafenib treatment (15.6% ± 11.4% to 5.4% ± 2.1%). Immunohistochemical analysis revealed significantly lower tumor vascularity in the therapy than in the control group (rat endothelial cell antigen 1, 74.4 ± 16.9 cells vs 197 ± 75.4 cells; p < 0.05). In sorafenib-treated tumors, significantly more apoptotic cells (terminal deoxynucleotidyl transferase-mediated nick end labeling, 6923 ± 3761 vs 3167 ± 1500; p < 0.05) and significantly fewer proliferating cells (Ki-67, 10,198 ± 3064 vs 15,003 ± 3674; p < 0.05) were observed than in the control group. Modest but significant correlations were observed between tumor perfusion and immunohistochemical tumor cell apoptosis (r = -0.56; p < 0.05) and between tumor perfusion and immunohistochemical tumor vascularity (r = 0.56; p < 0.05). Tumor perfusion quantified with gadobutrol-enhanced dynamic contrast-enhanced MRI can be used as a noninvasive surrogate parameter for monitoring the antiangiogenic, antiproliferative, and proapoptotic effects of sorafenib on prostate carcinoma allografts as validated with immunohistochemical analysis.
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1.42Impact points
Expert opinion: Dual energy CT: most and least relevant cardiopulmonary imaging applications.
Journal of thoracic imaging. 01/2012; 27(1):6.
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4.85Impact points
Accuracy of dynamic computed tomography adenosine stress myocardial perfusion imaging in estimating myocardial blood flow at various degrees of coronary artery stenosis using a porcine animal model.
Investigative radiology. 01/2012; 47(1):71-7.
To determine the accuracy of computed tomography (CT) dynamic stress myocardial perfusion imaging to estimate myocardial blood flow (MBF) in a porcine animal model with variable degrees of induced coronary artery stenosis in comparison with microsphere-derived MBF. Seven domestic pigs (36 ± 4 kg) re... [more] To determine the accuracy of computed tomography (CT) dynamic stress myocardial perfusion imaging to estimate myocardial blood flow (MBF) in a porcine animal model with variable degrees of induced coronary artery stenosis in comparison with microsphere-derived MBF. Seven domestic pigs (36 ± 4 kg) received stents (confirmed 3.0 mm diameter) in the left anterior descending coronary artery distal to first diagonal branch. A balloon catheter was placed within the stent and inflated to various degrees to obtain a defined luminal narrowing (50% and 75% diameter stenosis) as confirmed by intra-arterial flow wire measurement. All models underwent adenosine-mediated (140 μg/kg/min) dynamic stress and rest myocardial perfusion CT imaging using a dual-source CT scanner (shuttle-mode with 100 kV/300 mAs, 20 mL iopromide) with prospective acquisitions every second heartbeat for 30 seconds. CT-estimated MBF (MBFCT) was calculated using a model-based parametric deconvolution method and correlated to that of fluorescent microspheres (MBFmic) injected at each perfusion state. All study procedures were performed without complications, and all animals completed the study protocol. Among 448 myocardial segments, 31 (7%) were considered nonevaluable because of motion artifacts. With stress, MBFCT increased significantly (1.10 ± 0.25 vs. 0.80 ± 0.28 mL/g/min, P < 0.001; at stress and rest, respectively) in all myocardial segments and correlated with MBFmic (r = 0.67, P < 0.001). MBFCT overestimated MBFmic, independently of adenosine-stress and degree of coronary stenosis (β = 2.3, 95% confidence interval: 1.81-2.79 mL/g/min, P < 0.001). Although there were no differences in MBFCT between 50% and 75% coronary stenosis at rest (0.01 ± 0.08 mL/g/min, P = 0.86), MBFCT was significantly lower at 75% than at 50% under stress conditions (0.53 ± 0.19 vs. 0.71 ± 0.24 mL/g/min, P = 0.002). CT-derived MBF measurements at rest and stress with varying degrees of coronary stenosis show a valid difference but an underestimated correlation with microsphere-derived MBF in a porcine animal model.
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2.77Impact points
Value of oxygen-enhanced MRI of the lungs in patients with pulmonary hypertension: a qualitative and quantitative approach.
Journal of magnetic resonance imaging : JMRI. 01/2012; 35(1):86-94.
To assess the clinical value of oxygen-enhanced magnetic resonance imaging (oeMRI) in patients with pulmonary hypertension (PH) by correlation with ventilation/perfusion (V/Q) scintigraphy. In all, 33 patients with known PH underwent V/Q scintigraphy and oeMRI. oeMRI was used to assess the regional ... [more] To assess the clinical value of oxygen-enhanced magnetic resonance imaging (oeMRI) in patients with pulmonary hypertension (PH) by correlation with ventilation/perfusion (V/Q) scintigraphy. In all, 33 patients with known PH underwent V/Q scintigraphy and oeMRI. oeMRI was used to assess the regional pulmonary function based on relative-signal-enhancement (RSE) and cross-correlation-coefficient (CCC) maps, evaluating mean RSE (mRSE), fraction of oxygen-activated pixels (fOAP), and mean CCC (mCCC). Two reviewers, blinded to the results of scintigraphy, performed visual detection of diseased lung areas. In 26 of the 33 patients (79%) the image quality of oeMRI reached a diagnostic level. In total, 150 lung areas were analyzed and compared. Sensitivities/specificities of oeMRI for detecting these defects were: RSE vs. ventilation scintigraphy 92%/73%; RSE vs. perfusion scintigraphy 60%/87%; CCC vs. ventilation scintigraphy 89%/81%; CCC vs. perfusion scintigraphy 50%/87%. The number of diseased lung areas in oeMRI correlated significantly with the number in V/Q scintigraphy (P < 0.01). mRSE showed a significant correlation with the number of diseased lung areas in ventilation scintigraphy (P < 0.05). oeMRI is feasible in PH patients, yielding an overall moderate agreement between oeMRI and V/Q scans, with a good sensitivity of oeMRI for the detection of ventilation defects as compared with ventilation scintigraphy.
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2.28Impact points
Age determination of vessel wall hematoma in spontaneous cervical artery dissection: A multi-sequence 3T Cardiovascular Magnetic resonance study.
Journal of cardiovascular magnetic resonance : official journal of the Society for Cardiovascular Magnetic Resonance. 11/2011; 13:76.
ABSTRACT: Previously proposed classifications for carotid plaque and cerebral parenchymal hemorrhages are used to estimate the age of hematoma according to its signal intensities on T1w and T2w MR images. Using these classifications, we systematically investigated the value of cardiovascular magneti... [more] ABSTRACT: Previously proposed classifications for carotid plaque and cerebral parenchymal hemorrhages are used to estimate the age of hematoma according to its signal intensities on T1w and T2w MR images. Using these classifications, we systematically investigated the value of cardiovascular magnetic resonance (CMR) in determining the age of vessel wall hematoma (VWH) in patients with spontaneous cervical artery dissection (sCAD). 35 consecutive patients (mean age 43.6 ± 9.8 years) with sCAD received a cervical multi-sequence 3T CMR with fat-saturated black-blood T1w-, T2w- and TOF images. Age of sCAD was defined as time between onset of symptoms (stroke, TIA or Horner's syndrome) and the CMR scan. VWH were categorized into hyperacute, acute, early subacute, late subacute and chronic based on their signal intensities on T1w- and T2w images. The mean age of sCAD was 2.0, 5.8, 15.7 and 58.7 days in patients with acute, early subacute, late subacute and chronic VWH as classified by CMR (p < 0.001 for trend). Agreement was moderate between VWH types in our study and the previously proposed time scheme of signal evolution for cerebral hemorrhage, Cohen's kappa 0.43 (p < 0.001). There was a strong agreement of CMR VWH classification compared to the time scheme which was proposed for carotid intraplaque hematomas with Cohen's kappa of 0.74 (p < 0.001). Signal intensities of VWH in sCAD vary over time and multi-sequence CMR can help to determine the age of an arterial dissection. Furthermore, findings of this study suggest that the time course of carotid hematomas differs from that of cerebral hematomas.
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4.85Impact points
Dynamic contrast-enhanced computed tomography imaging biomarkers correlated with immunohistochemistry for monitoring the effects of sorafenib on experimental prostate carcinomas.
Investigative radiology. 09/2011; 47(1):49-57.
To investigate dynamic contrast-enhanced computed tomography (DCE-CT) for monitoring the effects of sorafenib on experimental prostate carcinomas in rats by quantitative assessments of tumor microcirculation parameters with immunohistochemical validation. Prostate carcinoma allografts (MLLB-2) impla... [more] To investigate dynamic contrast-enhanced computed tomography (DCE-CT) for monitoring the effects of sorafenib on experimental prostate carcinomas in rats by quantitative assessments of tumor microcirculation parameters with immunohistochemical validation. Prostate carcinoma allografts (MLLB-2) implanted subcutaneously in male Copenhagen rats (n=16) were imaged at baseline and after a 1-week treatment course of sorafenib using DCE-CT with iopromide (Ultravist 370, Bayer Pharma, Berlin, Germany) on a dual-source 128-slice CT (Somatom Definition FLASH, Siemens Healthcare, Forchheim, Germany). Scan parameters were as follows: detector width, 38.4 mm; contrast agent volume, 2 mL/kg bodyweight; injection rate, 0.5 mL/s; scan duration, 90 seconds; and temporal resolution, 0.5 seconds. The treatment group (n=8) received daily applications of sorafenib (10 mg/kg bodyweight) via gavage. Quantitative parameters of tumor microcirculation (plasma flow, mL/100 mL/min), endothelial permeability-surface area product (PS, mL/100 mL/min), and tumor vascularity (plasma volume, %) were calculated using a 2-compartment uptake model. DCE-CT parameters were correlated with immunohistochemical assessments of tumor vascularity (RECA-1), cell proliferation (Ki-67), and apoptosis (TUNEL). Sorafenib significantly (P < 0.05) suppressed tumor perfusion (25.1 ± 9.8 to 9.5 ± 6.0 mL/100 mL/min), tumor vascularity (15.6% ± 11.4% to 5.4% ± 2.1%), and PS (8.7 ± 4.5 to 2.7 ± 2.5 mL/100 mL/min) in prostate carcinomas during the treatment course. Immunohistochemistry revealed significantly lower tumor vascularity in the therapy group than in the control group (RECA-1; 181 ± 24 vs. 314 ± 47; P < 0.05). In sorafenib-treated tumors, significantly more apoptotic cells (TUNEL; 7132 ± 3141 vs. 3722 ± 1445; P < 0.05) and significantly less proliferating cells (Ki-67; 9628 ± 1.298 vs. 17,557 ± 1446; P < 0.05) were observed than those in the control group. DCE-CT tumor perfusion correlated significantly (P < 0.05) with tumor cell proliferation (Ki-67; r=0.55). DCE-CT tumor vascularity correlated significantly (P < 0.05) with immunohistochemical tumor cell apoptosis (TUNEL; r=-0.59) and tumor cell proliferation (Ki-67; r=0.68). DCE-CT endothelial PS correlated significantly (P < 0.05) with immunohistochemical tumor cell apoptosis (TUNEL; r=-0.6) and tumor vascularity (RECA-1; r=0.53). While performing corrections for multiple comparisons, we observed a significant correlation only between DCE-CT tumor vascularity (RECA-1) and tumor cell proliferation (Ki-67). Sorafenib significantly suppressed tumor perfusion, tumor vascularity, and PS quantified by DCE-CT in experimental prostate carcinomas in rats. These functional CT surrogate markers showed moderate correlations with antiangiogenic, antiproliferative, and proapoptotic effects observed by immunohistochemistry. DCE-CT may be applicable for the quantification of noninvasive imaging biomarkers of therapy response to antiangiogenic therapy.
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3.59Impact points
Severity assessment of pulmonary embolism using dual energy CT - correlation of a pulmonary perfusion defect score with clinical and morphological parameters of blood oxygenation and right ventricular failure.
European radiology. 09/2011; 22(2):269-78.
To correlate a Dual Energy (DE)-based visual perfusion defect scoring system with established CT-based and clinical parameters of pulmonary embolism (PE) severity. In 63 PE patients, DE perfusion maps were visually scored for perfusion defects (P-score). Vascular obstruction was quantified using the... [more] To correlate a Dual Energy (DE)-based visual perfusion defect scoring system with established CT-based and clinical parameters of pulmonary embolism (PE) severity. In 63 PE patients, DE perfusion maps were visually scored for perfusion defects (P-score). Vascular obstruction was quantified using the Mastora score. Both scores were correlated with short-axis diameters of the right and left ventricle, their ratio (RV/LV ratio), width of the pulmonary trunk, a number of clinical parameters and each other. Univariate and multivariate analyses were performed. Times to generate both scores were recorded. After univariate and multivariate analysis, a significant (p < 0.05) correlation with the P-score was shown for the Mastora score (r = 0.65), RV/LV ratio (r = 0.47), width of the pulmonary trunk (r = 0.26), troponin I (r = 0.43) and PaO(2) (r = -0.50). For the left ventricular diameter, only univariate analysis showed a significant correlation. Mastora score correlated significantly with RV/LV ratio (r = 0.36), width of the pulmonary trunk (r = 0.27), PaO(2) (r = -0.41) and troponin I (r = 0.37). Mean time for generating the P-score was significantly shorter than for the Mastora score. A DE-based P-score correlates with a number of parameters of PE severity. It might be easier and faster to perform than some traditional CT scoring methods for vascular obstruction.
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6.34Impact points
Detection of hemodynamically significant coronary artery stenosis: incremental diagnostic value of dynamic CT-based myocardial perfusion imaging.
Radiology. 09/2011; 260(3):689-98.
To determine the feasibility of computed tomography (CT)-based dynamic myocardial perfusion imaging for the detection of hemodynamically significant coronary artery stenosis, as defined with fractional flow reserve (FFR). Institutional review board approval and informed patient consent were obtained... [more] To determine the feasibility of computed tomography (CT)-based dynamic myocardial perfusion imaging for the detection of hemodynamically significant coronary artery stenosis, as defined with fractional flow reserve (FFR). Institutional review board approval and informed patient consent were obtained before patient enrollment in the study. The study was HIPAA compliant. Subjects who were suspected of having or were known to have coronary artery disease underwent electrocardiographically triggered dynamic stress myocardial perfusion imaging. FFR measurement was performed within all main coronary arteries with a luminal narrowing of 50%-85%. Estimated myocardial blood flow (MBF) was derived from CT images by using a model-based parametric deconvolution method for 16 myocardial segments and was related to hemodynamically significant coronary artery stenosis with an FFR of 0.75 or less in a blinded fashion. Conventional measures of diagnostic accuracy were derived, and discriminatory power analysis was performed by using logistic regression analysis. Of 36 enrolled subjects, 33 (mean age, 68.1 years ± 10 [standard deviation]; 25 [76%] men, eight [24%] women) completed the study protocol. An MBF cut point of 75 mL/100 mL/min provided the highest discriminatory power (C statistic, 0.707; P <.001). While the diagnostic accuracy of CT for the detection of anatomically significant coronary artery stenosis (>50%) was high, it was low for the detection of hemodynamically significant stenosis (positive predictive value [PPV] per coronary segment, 49%; 95% confidence interval [CI]: 36%, 60%). With use of estimated MBF to reclassify lesions depicted with CT angiography, 30 of 70 (43%) coronary lesions were graded as not hemodynamically significant, which significantly increased PPV to 78% (95% CI: 61%, 89%; P = .02). The presence of a coronary artery stenosis with a corresponding MBF less than 75 mL/100 mL/min had a high risk for hemodynamic significance (odds ratio, 86.9; 95% CI:17.6, 430.4). Dynamic CT-based stress myocardial perfusion imaging may allow detection of hemodynamically significant coronary artery stenosis.
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12.54Impact points
Meta-analysis and systematic review of the long-term predictive value of assessment of coronary atherosclerosis by contrast-enhanced coronary computed tomography angiography.
Journal of the American College of Cardiology. 06/2011; 57(24):2426-36.
We conducted a systematic review and meta-analysis to determine the predictive value of findings of coronary computed tomography angiography for incident cardiovascular events. Initial studies indicate a prognostic value of the technique; however, the level of evidence as well as exact independent r... [more] We conducted a systematic review and meta-analysis to determine the predictive value of findings of coronary computed tomography angiography for incident cardiovascular events. Initial studies indicate a prognostic value of the technique; however, the level of evidence as well as exact independent risk estimates remain unclear. We searched PubMed, EMBASE, and the Cochrane Library through January 2010 for studies that followed up ≥ 100 subjects for ≥ 1 year and reported at ≥ 1 hazard ratio (HR) of interest. Risk estimates for the presence of significant coronary stenosis (primary endpoint; ≥ 50% diameter stenosis), left main coronary artery stenosis, each coronary stenosis, 3-vessel disease, any plaque, per coronary segment containing plaque, and noncalcified plaque were derived in random effect regression analysis, and causes of heterogeneity were determined in meta-regression analysis. We identified 11 eligible articles including 7,335 participants (age 59.1 ± 2.6 years, 62.8% male) with suspected coronary artery disease. The presence of ≥ 1 significant coronary stenosis (9 studies, 3,670 participants, and 252 outcome events [6.8%] with 62% revascularizations) was associated with an annualized event rate of 11.9% (6.4% in studies excluding revascularization). The corresponding HR was 10.74 (98% confidence interval [CI]: 6.37 to 18.11) and 6.15 (95% CI: 3.22 to 11.74) in studies excluding revascularization. Adjustment for coronary calcification did not attenuate the prognostic significance (p = 0.79). The estimated HRs for left main stenosis, presence of plaque, and each coronary segment containing plaque were 6.64 (95% CI: 2.6 to 17.3), 4.51 (95% CI: 2.2 to 9.3), and 1.23 (95% CI: 1.17 to 1.29), respectively. Presence and extent of coronary artery disease on coronary computed tomography angiography are strong, independent predictors of cardiovascular events despite heterogeneity in endpoints, categorization of computed tomography findings, and study population.
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7.04Impact points
Vessel wall inflammation in spontaneous cervical artery dissection: a prospective, observational positron emission tomography, computed tomography, and magnetic resonance imaging study.
Stroke; a journal of cerebral circulation. 06/2011; 42(6):1563-8.
Vessel wall inflammation (VWI) may be a pathogenetic factor in cervical artery dissection (CAD). We used contrast-enhanced high-resolution MRI (hrMRI) and positron emission tomography CT (PET-CT) to systematically investigate VWI in spontaneous CAD. In this monocentric, prospective, observational st... [more] Vessel wall inflammation (VWI) may be a pathogenetic factor in cervical artery dissection (CAD). We used contrast-enhanced high-resolution MRI (hrMRI) and positron emission tomography CT (PET-CT) to systematically investigate VWI in spontaneous CAD. In this monocentric, prospective, observational study, all consecutive patients with acute, MRI-confirmed, spontaneous CAD admitted to our center between August 2007 and August 2009 were included. VWI was defined as perivascular contrast enhancement in hrMRI and increased perivascular [18F]-fluorodesoxyglucose uptake in PET-CT. VWI was further differentiated between local (restricted to the site of dissection) and generalized (exceeding the site of dissection). A total of 37 patients were included. Multiple dissections were seen in 10 patients (27%). Twenty-five patients received both modalities as planned, 8 received only PET-CT, and 4 received only hrMRI. A subset of patients showed signs of a generalized VWI in hrMRI (4/29 patients, 14%) and PET-CT (8/33 patients, 24%). In patients who received both modalities, all with hrMRI signs of generalized VWI were PET-CT positive (3/3), whereas some PET-CT-positive patients were hrMRI-negative (4/7). If present, generalized VWI in hrMRI completely resolved within 6 months. The presence of >2 simultaneous dissections (seen in 2 patients) was significantly associated with generalized VWI in hrMRI (P=0.015) but marginally not in PET-CT (P=0.053). A subset of patients with spontaneous CAD showed signs of a generalized transient inflammatory arteriopathy in contrast-enhanced hrMRI and PET-CT. This subset of patients may be more prone to multiple dissections.
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4.85Impact points
Quantification of supra-aortic arterial wall inflammation in patients with arteritis using high resolution dynamic contrast-enhanced magnetic resonance imaging: initial results in correlation to [18F]-FDG PET/CT.
Investigative radiology. 05/2011; 46(9):594-9.
: To compare [F]- -fluoro-D-glucose (FDG) positron emission tomography (PET)/computed tomography (CT), used in clinical routine to detect inflamed arteries in patients with arteritis, with high resolution dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) in its ability to measure infl... [more] : To compare [F]- -fluoro-D-glucose (FDG) positron emission tomography (PET)/computed tomography (CT), used in clinical routine to detect inflamed arteries in patients with arteritis, with high resolution dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) in its ability to measure inflammation in carotid and vertebral arteries. : This study was performed with written informed consent, Health Insurance Portability and Accountability Act (HIPAA) compliance, and institutional review board approval. DCE-MRI of the carotid and vertebral arteries of 17 patients with suspected arteritis was acquired at 3T (2D saturation-recovery spoiled gradient echo, in plane resolution 0.625 × 0.625 mm) using a dedicated 4-channel carotid coil. Patients underwent [F] FDG-PET/CT within 1 week of the MRI scan. The blood pool-corrected mean standardized uptake value (mean target-to-background ratio [TBRmean]) was measured on PET/CT images at the identical location as the region-of-interest in the magnetic resonance images. MRI signal intensity data was analyzed to generate estimates of the tissue extraction fraction and interstitial volume using a 2-compartment model. : [F]-FDG PET/CT TBRmean was significantly higher in patients with than without arteritis (1.55 ± 0.34 vs. 1.06 ± 0.14, P = 0.001). Patients diagnosed with arteritis had significantly higher extraction fractions as measured by DCE-MRI than patients without arteritis (8.79% ± 2.19% vs. 5.82% ± 1.13%, P = 0.002). TBRmean correlated significantly with the extraction fraction (r = 0.73, P < 0.001). DCE-MRI and FDG-PET/CT yielded the same sensitivity (86%) and specificity (90%) for the detection of arteritis. Intra- and interreader reproducibility was good with Intraclass Correlation Coefficients of 0.82 and 0.78, respectively. : DCE-MRI is able to measure arterial inflammation reliably and noninvasively with good correlation to [F]-FDG PET/CT in patients suffering from arteritis of the supraaortic arteries.
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2.40Impact points
Interrupted nitinol U-Clips versus standard running suture for the central arterial T-graft anastomosis: a prospective randomized study.
European journal of cardio-thoracic surgery : official journal of the European Association for Cardio-thoracic Surgery. 04/2011; 40(2):e93-7.
Studies carried out to date suggest that the interrupted suture technique using U-Clips for anastomoses in coronary surgery may be superior to the standard running polypropylene suture. The purpose of this study was to compare safety and effectiveness of a central T-graft anastomosis constructed wit... [more] Studies carried out to date suggest that the interrupted suture technique using U-Clips for anastomoses in coronary surgery may be superior to the standard running polypropylene suture. The purpose of this study was to compare safety and effectiveness of a central T-graft anastomosis constructed with the left internal thoracic artery (LITA) in situ (to the left anterior descending (LAD)) in which the free right internal thoracic artery (to the circumflex branch of the right coronary artery (RCX)) was implanted (RITA-to-LITA) using either self-closing nitinol U-Clips or simple continuous suture. We hypothesized that internal thoracic arteries could adapt their diameter to the blood flow. Thirty patients underwent total arterial revascularization using a T-graft constructed with free LITA in situ to LAD in which the free RITA to the circumflex artery was implanted (central T-graft anastomosis). In all cases, free RITA was used as a sequential graft with two peripheral anastomoses. Patients were randomly assigned to two groups: in group A (n=15), central T-graft anastomosis was performed using a standard 8/0 polypropylene running suture. In group B (n=15), central T-graft anastomosis was performed using U-Clips. Intra-operative transit time flow measurements were recorded. Patency control was performed in 30 patients 2 weeks and 6 months postoperatively, using 64-slice computed tomography (CT) angiography. The diameter of the LITA was measured proximal and distal and the diameter of the RITA distal to the central T-graft anastomosis. Perioperative results were similar in the two groups (P=ns). Intra-operative transit time flow measurement showed patent grafts in all patients. There were no hospital deaths. Two weeks postoperatively, all grafts were patent. At 6-month follow-up, one RITA and one LITA (both in group B) were closed distal to the central T-graft anastomosis. There was no death and no re-intervention during follow-up. Statistical analysis showed no significant changes in graft diameters after 2 weeks and 6 months in both groups. The U-Clip anastomosis technique is in our experience safe but not superior to the standard running suture using polypropylene material. Remodeling of the ITA grafts close to the central T-graft anastomosis was neither observed for the standard running suture nor for the U-Clip anastomoses.
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3.59Impact points
Magnetic resonance angiography of the carotid arteries: comparison of unenhanced and contrast enhanced techniques.
European radiology. 04/2011; 21(8):1667-76.
To compare different techniques for carotid imaging including contrast-enhanced, unenhanced and dynamic techniques to find an alternative to contrast-enhanced MRA. 43 patients referred for imaging of the carotids were enrolled in this IRB-approved study. Imaging included dark-blood, time-of-flight, ... [more] To compare different techniques for carotid imaging including contrast-enhanced, unenhanced and dynamic techniques to find an alternative to contrast-enhanced MRA. 43 patients referred for imaging of the carotids were enrolled in this IRB-approved study. Imaging included dark-blood, time-of-flight, ECG-gated SSFP and dynamic and static contrast-enhanced MRA. Two radiologists evaluated all datasets in terms of image quality (vessel lumen, signal homogeneity, diagnostic confidence, preferred technique) on a four-point Likert-scale and in measuring the vessel area. Of the 43 included patients the first 8 subjects served for protocol optimisation and 4 individuals discontinued the examination. Thus 31 datasets served for evaluation. CE-MRA revealed best results for delineation of vessel lumen, signal homogeneity and diagnostic confidence with values of 3.61, 3.42 and 3.77. It was also rated as the most preferred technique. SSFP-MRA was rated second in all categories with values of 3.1, 2.9 and 3.11. This unenhanced technique was the only one showing non-significantly different results in quantitative analysis. SSFP-MRA, an unenhanced form of MRA, represents an alternative to CE-MRA, particularly in patients where administration of gadolinium for CE-MRA may be contraindicated. In contrast to other techniques, SSFP-MRA serves with not significant different results compared to standard CE-MRA.
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MRI and CT in the diagnosis of coronary artery disease: indications and applications.
Insights into imaging. 02/2011; 2(1):9-24.
In recent years, technical advances and improvements in cardiac computed tomography (CT) and cardiac magnetic resonance imaging (MRI) have provoked increasing interest in the potential clinical role of these techniques in the non-invasive work-up of patients with suspected coronary artery disease (C... [more] In recent years, technical advances and improvements in cardiac computed tomography (CT) and cardiac magnetic resonance imaging (MRI) have provoked increasing interest in the potential clinical role of these techniques in the non-invasive work-up of patients with suspected coronary artery disease (CAD) and correct patient selection for these emerging imaging techniques. In the primary detection or exclusion of significant CAD, e.g. in the patient with unspecific thoracic complaints, and also in patients with known CAD or advanced stages of CAD, both CT and MRI yield specific advantages. In this review, the major aspects of non-invasive MR and CT imaging in the diagnosis of CAD will be discussed. The first part describes the clinical value of contrast-enhanced non-invasive CT coronary angiography (CTCA), including the diagnostic accuracy of CTCA for the exclusion or detection of significant CAD with coronary artery stenoses that may require angioplastic intervention, as well as potentially valuable information on the coronary artery vessel wall. In the second section, the potential of CT for the imaging of myocardial viability and perfusion will be highlighted. In the third and final part, the range of applications of cardiac MRI in CAD patients will be outlined.
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Prevalence of complicated carotid atherosclerotic plaques ispilateral to ischemic cryptogenic stroke using high-resolution mri
Journal of Cardiovascular Magnetic Resonance. 01/2011;
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2.15Impact points
Differential associations between blood biomarkers of inflammation, oxidation, and lipid metabolism with varying forms of coronary atherosclerotic plaque as quantified by coronary CT angiography.
The international journal of cardiovascular imaging. 01/2011; 28(1):183-92.
Although epidemiologic data link biomarkers of cardiovascular risk with incident and prevalent coronary artery disease, exact anatomic relationships between biomarkers and coronary atherosclerosis as measured by coronary CT angiography remain unclear. Patients with acute chest pain who ultimately ha... [more] Although epidemiologic data link biomarkers of cardiovascular risk with incident and prevalent coronary artery disease, exact anatomic relationships between biomarkers and coronary atherosclerosis as measured by coronary CT angiography remain unclear. Patients with acute chest pain who ultimately had no evidence of acute coronary syndrome underwent contrast-enhanced 64-slice coronary CT angiography to determine presence, extent and composition of coronary atherosclerotic plaque. We determined the differences in levels of blood biomarkers measured at the time of the CT scan between different CT-based atherosclerotic plaque groups. Among 313 patients (mean age: 51.6 ± 11 years, 62% male) high-sensitivity C-reactive protein (hs-CRP) and matrix metalloproteinase-2 were associated with the extent of calcified plaque (P = 0.03 and P < 0.001), while hs-CRP and apolipoprotein A1 were associated with the extent of non-calcified plaque (P = 0.03 and P = 0.004; respectively). Despite a generally lower risk profile, subjects with exclusively non-calcified plaque had significantly higher levels of hs-CRP and oxidized low-density lipoprotein (P = 0.01 and P = 0.03; respectively) and lower levels of adiponectin (P = 0.03) when compared to subjects with calcified plaque (n = 130, 42%). Biomarkers reflecting inflammation, vascular remodeling, oxidation, and lipoprotein metabolism maybe associated with different patterns of coronary atherosclerosis as quantified by coronary CT angiography.
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3.59Impact points
Metal artifact reduction by dual energy computed tomography using monoenergetic extrapolation.
European radiology. 01/2011; 21(7):1424-9.
The aim of the study was to assess the performance and diagnostic value of a dual energy CT approach to reduce metal artefacts in subjects with metallic implants. 31 patients were examined in the area of their metallic implants using a dual energy CT protocol (filtered 140 kVp and 100 kVp spectrum, ... [more] The aim of the study was to assess the performance and diagnostic value of a dual energy CT approach to reduce metal artefacts in subjects with metallic implants. 31 patients were examined in the area of their metallic implants using a dual energy CT protocol (filtered 140 kVp and 100 kVp spectrum, tube current relation: 3:1). Specific post-processing was applied to generate energies of standard 120 and 140 kVp spectra as well as a filtered 140 kVp spectrum with mean photon energies of 64, 69 and 88 keV, respectively, and an optimized hard spectrum of 95-150 keV. Image quality and diagnostic value were subjectively and objectively determined. Image quality was rated superior to the standard image in 29/31 high energy reconstructions; the diagnostic value was rated superior in 27 patients. Image quality and diagnostic value scores improved significantly from 3.5 to 2.1 and from 3.6 to 1.9, respectively. In several exams decisive diagnostic features were only discernible in the high energy reconstructions. The density of the artefacts decreased from -882 to -341 HU. Dual Energy CT with specific postprocessing can reduce metal artefacts and may significantly enhance diagnostic value in the evaluation of metallic implants.
Following (25)
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Berthold Kiefer
Siemens -
Wieland Sommer
Ludwig-Maximilians-Universität München -
Axel Rominger
Ludwig-Maximilians-Universität München -
Jose Raya
NYU Langone Medical Center -
Ingo Kaczmarek
Ludwig-Maximilians-Universität München
Topics (5)
