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  • 1
    Keywords: evaluation ; Germany ; THERAPY ; CLASSIFICATION ; CT ; DIAGNOSIS ; FOLLOW-UP ; imaging ; SPIRAL CT ; DISEASE ; NEW-YORK ; RISK ; computed tomography ; BLOOD-FLOW ; primary ; RISK-FACTORS ; MR ; MRI ; treatment ; MAGNETIC-RESONANCE ; magnetic resonance imaging ; risk factors ; RISK FACTOR ; tomography ; SCINTIGRAPHY ; COMPUTED-TOMOGRAPHY ; ORGANIZATION ; BREATH-HOLD TECHNIQUE ; MR imaging ; HELICAL CT ; DIFFERENTIAL-DIAGNOSIS ; ARTERIAL-HYPERTENSION ; LEFT-VENTRICULAR DYSFUNCTION ; CHEST-X-RAY ; CHRONIC THROMBOEMBOLISM ; pulmonary hypertension,computed tomography,magnetic resonance imaging,echocardiography,angiography,E ; RADIOLOGIC FEATURES
    Abstract: In the recent World Health Organization (WHO) classification the group of pulmonary arterial hypertension (PH) comprises the classic primary pulmonary hypertension and several conditions with definite or very high risk factors to develop pulmonary arterial hypertension. Therapeutic advances drive the need for a comprehensive pre-therapeutic evaluation for optimal treatment. Furthermore, follow-up examinations need to be performed to monitor changes in disease status and response to therapy. Up to now, the diagnostic imaging work-up of PH comprises mainly echocardiography, invasive right heart catheterization and ventilation/perfusion scintigraphy. Due to technical advances helical computed tomography (CT) and magnetic resonance imaging (MRI) became more important in the evaluation and for differential diagnosis of pulmonary arterial hypertension. Both modalities are reviewed and recommendations for clinical use are given
    Type of Publication: Journal article published
    PubMed ID: 14740163
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  • 2
    Keywords: measurement ; evaluation ; Germany ; LUNG ; PERFUSION ; imaging ; QUANTIFICATION ; VENTILATION ; TIME ; BLOOD-FLOW ; MR ; MRI ; SEQUENCE ; SIGNAL ; ACQUISITION ; DIFFERENCE ; REGION ; arteries ; REGIONS ; EMBOLISM ; ANGIOGRAPHY ; PULMONARY PERFUSION ; LUNG PERFUSION ; PULMONARY ; HEALTHY-VOLUNTEERS ; CINE-MRI ; perfusion,lung,phase-contrast,MRI,parallel imaging
    Abstract: Purpose: Evaluation of lung perfusion by contrast-enhanced 3D MRI using partial parallel imaging techniques. Materials and Methods: Eight healthy volunteers were examined using a contrast-enhanced dynamic FLASH 3D sequence with partial parallel imaging technique at 1.5 T MRI with a TA of 1.5 sec. The whole lung was covered by 36 coronal slices. A ventral, middle and dorsal, slice of each lung was manually segmented and signal-to-time curves were computed. For absolute quantification of blood flow through the right and left pulmonary artery, phase-contrast flow measurements were performed. Results: No significant difference was found between the signal intensity in the right (8.9 +/- 2.6) and left (8.0 +/- 3.5) lung, corresponding to a left-to-right signal intensity ratio of 0.9. A significantly higher signal intensity was found in the dorsal regions of the lungs (p = 0.01) compared to the ventral regions. The time to peak of the signal intensity was significantly shorter in the dorsal (15.3 sec) and middle (15.7 sec) regions of the lungs (p = 0.03 and p = 0.04, respectively) than in the ventral regions (16.3 sec). The ratio between blood flow through the left (2.2 L/min) and right (2.7 L/min) lung was 0.84. Conclusion: Partial parallel image acquisition can assess the perfusion of the lungs at high temporal resolution. The perfusion is slightly higher on the right than on the left. The signal increases faster and has a higher peak in the dorsal lung regions
    Type of Publication: Journal article published
    PubMed ID: 15026945
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  • 3
    Keywords: OPTIMIZATION ; BLOOD ; Germany ; DIAGNOSIS ; imaging ; ACCURACY ; TIME ; PATIENT ; CONTRAST ; CONTRAST AGENT ; SEQUENCE ; ACQUISITION ; PARAMETERS ; CURVES ; MAGNETIC-RESONANCE ANGIOGRAPHY ; magnetic resonance angiography ; GD-DTPA ; BOLUS ; AGENT ; TRANSIT-TIME ; normalization ; intensity ; PHASE ; POWER ; contrast-enhanced ; PULMONARY-ARTERIES ; TEMPORAL RESOLUTION ; geometry of contrast bolus ; RENAL-ARTERIES ; thoracic vessels ; VASCULAR SYSTEM
    Abstract: Purpose: Little is known about the dispersion of a defined contrast bolus during its passage through the heart and pulmonary vasculature. The Purpose of this study was to analyze factors influencing a defined contrast bolus for ce-MRA of thoracic vessels. Materials and Methods: For analysis of bolus geometry, an ECG-gated saturation-recovery Turbo-Flash sequence with a TI of 20 msec was used. it was acquired axially at the level of the pulmonary trunc, so that with one data acquisition a curve analysis was possible in the ascending and descending aorta, and in the pulmonary trunc. Twenty-nine patients received 3 ml of Gd-DTPA diluted with saline to a total of 20 ml. Contrast injection was done using a MR compatible power injector with injection rates varying between 1, 2 and 4 ml/sec. Each injection was followed by a saline flush of 20ml with the same injection rate and mode. Cardiac function was assessed by cine imaging, and phase contrast measurements. After normalization to baseline signal intensity (SI), bolus curves were fitted using a gamma-variate fit and peak signal intensity (peak SI), time-to-peak (TP), upslope, mean transit time (MTT) and dispersion of the contrast bolus were calculated. Furthermore, T, and [Gd] in the experimental setting were calculated as follows: T-1 =T-1o/ In [SI/Sl(0)], and [Gd](exp) [1/T-1 - 1/T-1o]/ R-1. They were then extrapolated [Gd] to clinical conditions by [Gd](clin) = [Gd](exp) (.) 10/1.5, and minimal blood T-1 by T-1clin = 1 / [1/T-1o + R-1 [Gd](clin)]. Results: With increasing injection rate, there was a significant decrease (p < 0.001) of MTT in all target vessels. However, this decrease was not linear: a 4-fold increase in injection rate lead to a 2-fold decrease in MTT e. g. in the ascending aorta. MTT was significantly shorter in the pulmonary trunc compared with that in the ascending and descending aorta (p < 0.001), regardless of injection rate (p < 0.001). Vice versa, dispersion of the contrast bolus was significantly lower in the pulmonary trunc, and increased with higher injection rates. There was no clinically relevant difference in minimal blood T, between the different target vessels, for clinical conditions extrapolated values ranged between 20 und 79 msec. Heart function parameters only had a minor influence of bolus curve parameters. Conclusion: Analysis of bolus geometry enables determination of transit times of a defined contrast bolus through a defined target vessel in the thoracic cavity. Bolus geometry is mainly determined by injection parameters, cardiac function is of minor importance. Dispersion of contrast bolus and M17 increase from the pulmonary trunc to the ascending aorta. The knowledge of these facts may help optimizing of injection parameters and the total amount of contrast agent for contrast-enhanced MRA of thoracic vessels
    Type of Publication: Journal article published
    PubMed ID: 15871079
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  • 4
    Keywords: Aorta, ASCENDING AORTA, BLOOD, blood flow, BLOOD-FLOW, bronchosystemic shunt, CINE MRI, ECG gating,
    Abstract: Purpose: Different ECG gating techniques are available for MR phase-contrast (PC) flow measurements. Until now no study has reported the impact of different ECG gating techniques on quantitative flow parameters. The goal was to evaluate the impact of the gating method and the breathing schema on the pulmonary, systemic and bronchosystemic circulation. Material and methods: Twenty volunteers were examined (1.5 T) with free breathing phase-contrast flow (PC-flow) measurements with prospective (free-prospective) and retrospective (free-retrospective) ECG gating. Additionally, expiratory breath-hold retrospective ECG gated measurements (bh-retrospective) were performed. Blood flow per minute; peak velocity and time to peak velocity were compared. The clinically important difference between the systemic and pulmonary circulation (bronchosystemic shunt) was calculated. Results: Blood flow per minute was lowest for free-prospective (6 l/min, pulmonary trunc) and highest for bh-retrospective measurements (6.9 l/min, pulmonary trunc). No clinically significant difference in peak velocity was assessed (82-83 cm/s pulmonary trunc, 109-113 cm/s aorta). Time to peak velocity was shorter for retro-gated free-retrospective and bh-retrospective than for pro-gated free-prospective. The difference between systemic and pulmonary measurements was least for the free-retrospective technique. Conclusion: The type of gating has a significant impact on flow measurements. Therefore, it is important to use the same ECG gating method, especially for follow-up examinations. Retrospective ECG gated free breathing measurements allow for the most precise assessment of the bronchosystemic blood flow and should be used in clinical routine. (C) 2006 Elsevier Ireland Ltd. All rights reserved
    Type of Publication: Journal article published
    PubMed ID: 17023135
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  • 5
    Keywords: BLOOD ; Germany ; LUNG ; QUANTIFICATION ; TIME ; BLOOD-FLOW ; blood flow ; FLOW ; MRI ; PATTERNS ; PARAMETERS ; HYPERTENSION ; BLOOD-FLOW MEASUREMENTS ; BREATH-HOLD ; ENCODED CINE MRI ; HEMODYNAMICS ; RE ; HEALTHY-VOLUNTEERS ; phase-contrast MRI ; pulmonary circulation ; systemic circulation ; VENTRICULAR STROKE VOLUME
    Abstract: OBJECTIVE. The purpose of this study was to use phase-contrast MRI to evaluate the influence of various breathing maneuvers on the hemodynamics of the pulmonary and systemic arterial circulation. SUBJECTS AND METHODS. Twenty-five volunteers were examined with phase-contrast MRI. Flow measurements were acquired in the aorta, pulmonary trunk, and left and right pulmonary arteries during deep, large-volume inspiratory breath-hold, expiratory breath-hold, and smooth respiration (no breath-hold). Parameters assessed were peak velocity, blood flow, velocity gradient, and acceleration time. RESULTS. Pulmonary blood flow and peak velocity were significantly reduced during inspiratory breath-hold and expiratory breath-hold compared with no breath-hold (p 〈 0.01). Pulmonary velocity gradient in inspiratory breath-hold was significantly (p:! 0.01) lower than in expiratory breath-hold and no breath-hold. There was no difference in velocity gradient between expiratory breath-hold and no breath-hold. Peak velocity in the aorta was lowest with no breath-hold. Velocity gradient was highest in expiratory breath-hold, and no breath-hold had the smallest SD. Acceleration time in the pulmonary trunk showed no difference between inspiratory breath-hold, expiratory breath-hold, and no breath-hold. Blood flow distribution to the left (45-47%) and to the right (53-55%) lung was not influenced by breathing maneuver. CONCLUSION. Measurements during smooth respiration showed the smallest SD. Therefore, no-breath-hold measurements should be considered for assessment of hemodynamics in clinical practice
    Type of Publication: Journal article published
    PubMed ID: 16861549
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  • 6
    Keywords: ABNORMALITIES, CARDIAC-CATHETERIZATION, CHILDREN, COMPLEX, COMPLEXES, COMPUTED-TOMOGRAPHY, DISEASE,
    Abstract: Congenital heart disease (CHD), including complex anomalies of the pulmonary arteries, are now earlier diagnosed and treated. Due to improvements in interventional and surgical therapy, the number of patients with the need for follow-up examinations is increasing. Pre- and postinterventional imaging should be done as gently as possible, avoiding invasive techniques if possible. With the technical improvement of multidetector-row computed tomography (MDCT) and magnetic resonance imaging (MRI), both techniques are increasingly used for noninvasive assessment of the pulmonary vasculature in children with CHD. Knowledge of the most common diseases affecting the pulmonary vasculature and the kind of surgical and interventional procedures is essential for optimal imaging planning. This is especially important because interventions can be positively influenced by high-quality imaging. Therefore, the most common diseases and procedures are described and imaging modality of choice and important image findings are discussed
    Type of Publication: Journal article published
    PubMed ID: 16799783
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  • 7
    Keywords: SIMULATIONS ; BLOOD ; Germany ; LUNG ; MODEL ; PERFUSION ; imaging ; QUANTIFICATION ; VOLUME ; TISSUE ; ACCURACY ; validation ; TIME ; BLOOD-FLOW ; pig ; BODY-WEIGHT ; CONTRAST ; SIMULATION ; CONTRAST AGENT ; MRI ; SIGNAL ; MAGNETIC-RESONANCE ; magnetic resonance imaging ; ACID ; RELAXATION ; HUMANS ; REGION ; EXCHANGE ; PARAMETERS ; positron emission tomography ; POSITRON-EMISSION-TOMOGRAPHY ; tomography ; PET ; PULMONARY PERFUSION ; GD-DTPA ; CALIBRATION ; RECONSTRUCTION ; LUNG PERFUSION ; QUANTITATIVE ASSESSMENT ; AGENT ; radiology ; DEPENDENCE ; WEIGHT ; ENHANCED MRI ; intensity ; USA ; EMISSION-TOMOGRAPHY ; MYOCARDIAL-PERFUSION ; ERROR ; perfusion MRI ; Relaxation time ; WATER DIFFUSION
    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 (H2O)-O-15 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. Magn Reson Med 62:476-487, 2009. (C) 2009 Wiley-Liss, Inc
    Type of Publication: Journal article published
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  • 8
    Keywords: CONTRAST AGENTS ; CARCINOMA IN-SITU ; DIAGNOSTIC-ACCURACY ; BRAIN-TUMORS ; MUTATION CARRIERS ; ENHANCED MRI ; TEMPORAL RESOLUTION ; 3 TESLA ; CONTRALATERAL BREAST ; LESION DETECTION
    Abstract: Purpose: To intraindividually compare 0.1 mmol/kg doses of gadobenate dimeglumine and gadopentetate dimeglumine for contrast material-enhanced breast magnetic resonance (MR) imaging by using a prospective, multicenter double-blind, randomized protocol. Materials and Methods: Institutional review board approval and patient informed consent were obtained. One hundred sixty-two women (mean age, 52.8 years +/- 12.3 [standard deviation]) enrolled at 17 sites in Europe and China between July 2007 and May 2009 underwent at least one breast MR imaging examination at 1.5 T by using three-dimensional spoiled gradient-echo sequences. Of these, 151 women received both contrast agents in randomized order in otherwise identical examinations separated by more than 2 but less than 7 days. Images, acquired at 2-minute or shorter intervals after contrast agent injection, were evaluated independently by three blinded radiologists unaffiliated with enrollment centers. Histopathologic confirmation was available for all malignant lesions (n = 144), while benign lesions were confirmed either by using histopathologic examination (n = 52) or by at least 12-month diagnostic follow-up (n = 20) with mammography and/or ultrasonography. Determinations of malignant lesion detection rates and diagnostic performance (sensitivity, specificity, accuracy, positive predictive value [PPV], and negative predictive value [NPV]) were performed and compared (McNemar and Wald tests). A full safety assessment was performed. Results: Significant superiority for gadobenate dimeglumine was noted by readers 1, 2, and 3 for malignant lesion detection rate (91.7%, 93.1%, 94.4% vs 79.9%, 80.6%, 83.3%, respectively; P 〈= .0003). Readers 1, 2, and 3 reported significantly superior diagnostic performance (sensitivity, specificity, and accuracy) for breast cancer detection with gadobenate dimeglumine (91.1%, 94.5%, 95.2% vs 81.2%, 82.6%, 84.6%; 99.0%, 98.2%, 96.9% vs 97.8%, 96.9%, 93.8%; 98.2%, 97.8%, 96.7% vs 96.1%, 95.4%, 92.8%, respectively; P 〈= .0094) and significantly superior PPV (91.1%, 85.2%, 77.2% vs 80.7%, 75.5%, 60.9%, respectively; P 〈= .0002) and NPV (99.0%, 99.4%, 99.4% vs 97.8%, 98.0%, 98.1%, respectively; P 〈= .0003). No safety concerns were noted with either agent. Conclusion: Gadobenate dimeglumine is superior to gadopentetate dimeglumine for breast cancer diagnosis. (C)RSNA, 2010 Clinical trial registration no. NCT00486473 (http://www.clinicaltrials.gov/). Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.10100968/-/DC1
    Type of Publication: Journal article published
    PubMed ID: 21163915
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  • 9
    Keywords: chronic thromboembolic pulmonary hypertension, CT ANGIOGRAPHY, development, DIAGNOSIS, DISEASE, EMBO
    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
    Type of Publication: Journal article published
    PubMed ID: 16838142
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  • 10
    Keywords: measurement ; Germany ; FOLLOW-UP ; follow-up studies ; SPIRAL CT ; VOLUME ; HEART ; SURGERY ; PATIENT ; REDUCTION ; FLOW ; MR ; MRI ; resistance ; DECREASE ; REPRODUCIBILITY ; arteries ; PRESSURE ; EMBOLISM ; VASCULATURE ; MOTION ; ARTERY ; HYPERTENSION ; BLOOD-FLOW MEASUREMENTS ; BREATH-HOLD ; chronic thromboembolic pulmonary hypertension,hemodynamics/flow,MR imaging,pulmonary arteries ; ENCODED CINE MRI ; HELICAL CT ; HEMODYNAMICS ; RIGHT-VENTRICULAR VOLUMES ; THROMBOENDARTERECTOMY ; vascular resistance ; chronic thromboembolic pulmonary hypertension
    Abstract: Purpose: To evaluate the potential of MRI to grade cardiac impairment and pulmonary hypertension in patients with chronic thromboembolic pulmonary hypertension (CTEPH) in comparison with invasive pressure measurements before and after surgery. Materials and Methods: We examined 35 patients with CTEPH before and after pulmonary thromboendarterectomy (PTE). For assessment of hemodynamics, velocity-encoded segmented GE-sequences (pulmonary arteries and ascending aorta) and segmented cine GE-sequences along the short axis of the heart were performed. The analysis comprised calculation of ejection fractions, peak velocities, mean pulmonary arterial flow and vessel diameter. 10 volunteers served as controls. Flow measurements were compared to invasively measured mean pulmonary arterial pressure (MPAP) and vascular resistance (PVR). Results: Compared to volunteers, CTEPH-patients showed significantly reduced right ventricular ejection fractions (p 〈 0.001), pulmonary peak velocity (p 〈 0.001) and significantly increased diameters of the pulmonary arteries (p 〈 0.001). The flow measurements in the aorta (2713 ml/min) and the pulmonary arteries (2088 ml/min) revealed a large bronchopulmonary shunt. After PTE, there was a significant reduction in vessel diameter (p 〈 0.001). This was associated with a significant increase in pulmonary peak velocities (p 〈 0.001). The increase in pulmonary peak velocities Correlated with the decrease of PVR (r = 0.5) and MPAP (r = 0.6). The ejection fraction of the right ventricle correlated with PVR (r = 0.6) and MPAP (r = 0.7). The postoperative decrease in MPAP correlated with the increase in right ventricular ejection fraction (r = 0.8). After PTE there was no bronchopulmonary shunt volume. All patients had an inverse motion of the interventricular septum. It returned to normal in 68 % of patients after surgery. Conclusion: Breath-hold MR-techniques enable non-invasive assessment of pulmonary hemodynamics in patients with CTEPH. For postoperative follow-up studies MRI could be considered the modality of choice
    Type of Publication: Journal article published
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