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Antonella Filippone,
Anthony Blakeborough,
Josy Breuer,
Luigi Grazioli,
Simone Gschwend,
Renate Hammerstingl,
Gertraud Heinz-Peer,
Thomas Kittner,
Andrea Laghi,
Edward Leen, [......],
Olivier Lucidarme,
Philipp Remplik,
Philip J Robinson, Stefan G Ruehm,
Fritz Schaefer,
Christoforos Stoupis,
Bernd Tombach,
Pierre-Jean Valette,
Christoph J Zech,
Alexander Huppertz
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ABSTRACT: To compare enhancement of liver parenchyma in MR imaging after injection of hepatocyte-specific contrast media.
Patients (n = 295) with known/suspected focal liver lesions randomly received 0.025 mmol gadoxetic acid/kg body weight or 0.05 mmol gadobenate dimeglumine/kg body weight by means of bolus injection. MR imaging was performed before and immediately after injection, and in the delayed phase at approved time points (20 min after injection of gadoxetic acid and 40 min after injection of gadobenate dimeglumine). The relative liver enhancement for the overall population and a cirrhotic subgroup was compared in T1-weighted GRE sequences. An independent radiologist performed signal intensity measurements. Enhancement ratios were compared using confidence intervals (CIs).
The relative liver enhancement in the overall population was superior with gadoxetic acid (57.24%) versus gadobenate dimeglumine (32.77%) in the delayed-imaging phase. The enhancement ratio between the contrast media was statistically significant at 1.75 (95% CI: 1.46-2.13). In the delayed phase, the enhancement of cirrhotic liver with gadoxetic acid (57.00%) was comparable to that in the overall population. Enhancement with gadobenate dimeglumine was inferior in cirrhotic liver parenchyma (26.85%).
In the delayed, hepatocyte-specific phase, liver enhancement after injection of gadoxetic acid was superior to that obtained with gadobenate dimeglumine.
Journal of Magnetic Resonance Imaging 02/2010; 31(2):356-64. · 2.70 Impact Factor
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Antonella Filippone MD,
Anthony Blakeborough MD,
Josy Breuer MD,
Luigi Grazioli MD,
PhD Simone Gschwend MD,
Renate Hammerstingl MD,
Gertraud Heinz-Peer MD,
Thomas Kittner MD,
Andrea Laghi MD,
Edward Leen MD, [......],
Olivier Lucidarme,
Philipp Remplik,
Philip J. Robinson, Stefan G. Ruehm,
Fritz Schaefer,
Christoforos Stoupis,
Bernd Tombach,
Pierre‐Jean Valette,
Christoph J. Zech,
Alexander Huppertz
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ABSTRACT: Purpose:To compare enhancement of liver parenchyma in MR imaging after injection of hepatocyte-specific contrast media.Materials and Methods:Patients (n = 295) with known/suspected focal liver lesions randomly received 0.025 mmol gadoxetic acid/kg body weight or 0.05 mmol gadobenate dimeglumine/kg body weight by means of bolus injection. MR imaging was performed before and immediately after injection, and in the delayed phase at approved time points (20 min after injection of gadoxetic acid and 40 min after injection of gadobenate dimeglumine). The relative liver enhancement for the overall population and a cirrhotic subgroup was compared in T1-weighted GRE sequences. An independent radiologist performed signal intensity measurements. Enhancement ratios were compared using confidence intervals (CIs).Results:The relative liver enhancement in the overall population was superior with gadoxetic acid (57.24%) versus gadobenate dimeglumine (32.77%) in the delayed-imaging phase. The enhancement ratio between the contrast media was statistically significant at 1.75 (95% CI: 1.46–2.13). In the delayed phase, the enhancement of cirrhotic liver with gadoxetic acid (57.00%) was comparable to that in the overall population. Enhancement with gadobenate dimeglumine was inferior in cirrhotic liver parenchyma (26.85%).Conclusion:In the delayed, hepatocyte-specific phase, liver enhancement after injection of gadoxetic acid was superior to that obtained with gadobenate dimeglumine. J. Magn. Reson. Imaging 2010; 31: 356–364. © 2010 Wiley-Liss, Inc.
Journal of Magnetic Resonance Imaging 01/2010; 31(2):356 - 364. · 2.70 Impact Factor
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ABSTRACT: The purpose of this study was to determine the image quality and diagnostic accuracy of three-dimensional (3D) unenhanced steady state free precession (SSFP) magnetic resonance angiography (MRA) for the evaluation of thoracic aortic diseases.
Fifty consecutive patients with known or suspected thoracic aortic disease underwent free-breathing ECG-gated unenhanced SSFP MRA with non-selective radiofrequency excitation and contrast-enhanced (CE) MRA of the thorax at 1.5 T. Two readers independently evaluated the two datasets for image quality in the aortic root, ascending aorta, aortic arch, descending aorta, and origins of supra-aortic arteries, and for abnormal findings. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were determined for both datasets. Sensitivity, specificity, and diagnostic accuracy of unenhanced SSFP MRA for the diagnosis of aortic abnormalities were determined.
Abnormal aortic findings, including aneurysm (n = 47), coarctation (n = 14), dissection (n = 12), aortic graft (n = 6), intramural hematoma (n = 11), mural thrombus in the aortic arch (n = 1), and penetrating aortic ulcer (n = 9), were confidently detected on both datasets. Sensitivity, specificity, and diagnostic accuracy of SSFP MRA for the detection of aortic disease were 100% with CE-MRA serving as a reference standard. Image quality of the aortic root was significantly higher on SSFP MRA (P < 0.001) with no significant difference for other aortic segments (P > 0.05). SNR and CNR values were higher for all segments on SSFP MRA (P < 0.01).
Our results suggest that free-breathing navigator-gated 3D SSFP MRA with non-selective radiofrequency excitation is a promising technique that provides high image quality and diagnostic accuracy for the assessment of thoracic aortic disease without the need for intravenous contrast material.
European Radiology 12/2009; 20(6):1311-20. · 3.22 Impact Factor
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ABSTRACT: The objective of our study was to assess the feasibility and diagnostic performance of time-resolved MR angiography (MRA) in the evaluation of central thoracic venous occlusive disease and to compare time-resolved MRA with conventional MRA and catheter angiography.
Twenty patients (eight women and 12 men; age range, 19-74 years) with suspected central thoracic venous occlusive disease underwent time-resolved MRA using time-resolved angiography with interleaved stochastic trajectories (TWIST) and parallel acquisition, followed by conventional MRA. Catheter angiography was performed within 1-14 days after MRA and was available for a total of 60 segments for correlation. Time-resolved and conventional MRA images were evaluated in separate reading sessions by two independent radiologists for image quality and level of confidence and degree of venoocclusive disease. The interobserver and intermodality agreement, sensitivity, and specificity were calculated using catheter angiography as the standard of reference.
Time-resolved MRA resulted in diagnostic-quality images that did not differ significantly in quality compared with conventional MRA. Thirty-one segmental venous stenoses were identified. The kappa coefficient revealed moderate intermodality agreement (kappa = 0.54; 95% CI, 0.32-0.76) between time-resolved MRA and conventional MRA. When compared with catheter angiography, the sensitivity and specificity for the diagnosis of significant stenosis (> or = 70%) were 87.5% and 68% for time-resolved MRA and 90% and 90% for conventional MRA, respectively.
Time-resolved MRA, as described in this study, has the potential to be used as an initial and screening diagnostic tool obviating conventional MRA and its associated higher contrast dose in normal and near-normal examinations. However, because of its relatively lower specificity, adjunct use of conventional MRA is still required for accurate grading of venous occlusive disease.
American Journal of Roentgenology 07/2009; 192(6):1731-8. · 2.78 Impact Factor
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ABSTRACT: The purposes of this study were to evaluate the quality and radiation exposure of data acquired with dual-energy CT compared with single-energy MDCT in the depiction of lower-extremity tendons and to assess whether a dual-energy CT voltage exists at which the quality of tendon depiction is optimal.
Eleven healthy volunteers and seven clinically referred patients (10 men, eight women; mean age, 43.1 years; range, 20-71 years) underwent conventional single-energy CT and dual-energy CT examinations of both lower extremities with a dual-source CT scanner. Dual-energy reconstructions were made at combined tube voltages approximating 86, 98, 110, 122, and 134 kVp. Quantitative and qualitative analyses were performed on six tendons in each lower extremity, and the findings were compared with single-energy CT findings. The radiation dose involved was recorded in each case.
A trend toward increasing tendon attenuation was observed with increasing reconstructed tube voltage. The group of single-energy CT reconstructions proved significantly superior to each of the dual-energy CT reconstructions with regard to signal-to-noise ratio (F = 35.25, p < 0.0001) and contrast-to-noise ratio (F = 37.19, p < 0.0001), although interobserver agreement in subjective ranking was poor. Dual-energy CT had a significantly higher radiation dose (p < 0.05) than single-energy CT.
Dual-energy CT of lower-extremity tendons, irrespective of the reconstruction tube voltage chosen, yields multiplanar reformations inferior to those of single-energy CT with regard to signal-to-noise and contrast-to-noise ratios while involving significantly escalated patient exposure to ionizing radiation. Whether the tissue-differentiating promise of dual-energy CT is realized in future studies and warrants such concessions remains to be seen.
American Journal of Roentgenology 11/2008; 191(5):1386-90. · 2.78 Impact Factor
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ABSTRACT: To determine whether contrast material dose reduction at 3.0 T allows preserved image quality for high-spatial-resolution magnetic resonance (MR) angiography of the lower extremities.
Forty-five consecutive patients (27 men, 18 women; mean age, 64 years) underwent contrast material-enhanced MR angiography of the lower extremities at 3.0 T. A waiver of informed consent was granted by the institutional review board. Sixteen patients received high-dose (approximately 0.3 mmol/kg), 15 received intermediate-dose (approximately 0.2 mmol/kg), and 14 received low-dose (approximately 0.1 mmol/kg) gadopentetate dimeglumine during a three-station, dual-injection examination. For scoring purposes, the arterial system from the celiac trunk to the plantar arteries was divided into 34 segments. The images were retrospectively and independently evaluated by two specialized radiologists who were blinded to the patient dose groups. All studies were assessed for overall image quality and the degree of contaminating venous enhancement. Each arterial segment was scored for the quality of vessel definition, the severity of stenoses, and the presence of collateral vessels.
More than 99% of arterial segments were found to be of diagnostic image quality by both readers in all dose groups. Generalized estimating equation analysis showed a significant difference among the three groups with regard to vessel definition (P = .019). No significant difference was found between the high- and intermediate-dose groups; however, the low-dose group had significantly better vessel definition compared with the high-dose (P = .034) and intermediate-dose (P = .015) groups. There was no significant difference among the groups in visualization of collateral vessels. Venous contamination was seen less frequently in the low-dose group, but the difference did not achieve significance.
The study showed that, compared with widely used dose strategies at 1.5 T, the contrast agent dose for 3.0-T lower extremity MR angiography can be reduced multifold without compromising image quality.
Radiology 09/2008; 248(2):680-92. · 5.73 Impact Factor
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ABSTRACT: To evaluate the feasibility of three-dimensional (3D) steady-state free-precession (SSFP) magnetic resonance angiography (MRA) using nonselective radiofrequency excitation in the assessment of cardiac morphology, thoracic aorta, main pulmonary, and proximal coronary arteries.
Thirty consecutive patients (19 males; 11 females; age range, 20-74) with various cardiac and thoracic vascular diseases underwent free-breathing respiratory navigator-gated electrocardiogram-triggered noncontrast SSFP MRA and conventional high-resolution 3D contrast-enhanced MRA (CE-MRA) of the thorax at 1.5 T. Two readers evaluated both datasets for findings, vascular delineation and sharpness (from 0, not visualized to 3, excellent definition), artifacts, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) in 14 vascular segments including aorta, supra-aortic, pulmonary, and coronary arteries, and in cardiac chambers. Statistical analysis was performed using Wilcoxon test for vessel delineation, and [kappa] coefficient for interobserver variability.
3D SSFP and CE-MRA were successfully performed in all patients. Scan time for SSFP MRA ranged from 5 to 10 minutes (mean +/- standard deviation, 7 +/- 2 minutes). On SSFP MRA, readers 1 and 2 graded 233 (97.1%) and 234 (97.5%) coronary arterial segments and cardiac chambers, and 275 (91.7%) and 278 (92.7%) noncoronary arterial segments with diagnostic definition (grades 2 and 3) (k = 0.86). On conventional CE-MRA, readers 1 and 2 graded 10 (4.2%) and 12 (5%) coronary arterial segments and cardiac chambers, and 272 (90.7%) and 270 (90%) noncoronary arterial segments with diagnostic definition (grades 2 and 3) (k = 0.89). Segmental visibility was higher for aortic root, pulmonary trunk, proximal coronary arteries, and heart chambers (P < 0.001), and lower for supra-aortic arteries (P < 0.001) on SSFP MRA for each reader. SNR and CNR values were higher for aortic root and aorta on SSFP MRA (P < 0.001 for both). No significant difference existed between SNR and CNR values for the other vascular segments and cardiac chambers on SSFP and CE-MRA (P > 0.05 for all). The 2 readers demonstrated vascular stenosis and dilatation/aneurysm in 7 and 35 segments on both datasets, respectively.
Noncontrast 3D SSFP MRA with nonselective radiofrequency excitation provides high image quality and sufficient SNR and CNR for confident assessment of cardiac and thoracic vascular diseases including congenital heart diseases. Our results suggest that noncontrast SSFP MRA outperforms CE-MRA in visualization of cardiac chambers, proximal coronary arteries, pulmonary trunk, and aortic root.
Investigative Radiology 06/2008; 43(6):411-20. · 4.59 Impact Factor
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ABSTRACT: The objective was to assess the feasibility of a combined arterial and venous whole-body three-dimensional magnetic resonance (MR) angiography, together with a cardiac MR examination, in patients with arterial thromboembolism. Ten patients with arterial thromboembolism underwent a contrast-enhanced whole-body MR examination of the arterial and venous vessels, followed by a cardiac MR examination on a separate occasion within 24 h. All examinations were performed on a 1.5-T MR scanner. For both arterial and venous MR angiography only one injection of contrast agent was necessary. The cardiac imaging protocol included dark-blood-prepared half-Fourier acquisition single-shot turbo-spin-echo sequences, fast steady-state free precession cine sequences, T2-weighted turbo-spin-echo sequences and inversion recovery gradient-echo fast low-angle-shot sequences after injection of contrast agent. MR imaging revealed additional clinically unknown arterial thromboembolisms in four patients. The thoracic aorta was depicted as embolic source in four patients, while deep vein thrombosis (DVT) was found in one patient as the underlying disease. Unsuspected infarction of parenchymal organs was detected by MRI in two patients. An unknown additional DVT was found in one patient. Four patients were considered to have arterial emboli of cardiac origin. In conclusion, acquisition of arterial and venous MR angiograms of the entire vascular system combined with cardiac MR imaging is a most comprehensive and valuable strategy in patients with arterial thromboembolism.
European Radiology 06/2008; 18(5):983-92. · 3.22 Impact Factor
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ABSTRACT: Bone subtraction techniques have been shown to enhance cranial computed tomography angiography (CTA). The aims of this study were to assess the feasibility of bone subtraction CTA (BSCTA) in cervical CTA, test whether a late venous CT (LVCT) scan can be used as bone mask instead of a low-dose nonenhanced CT (NECT), and to evaluate the impact of patient motion on image quality.
Thirty-six patients underwent BSCTA for the evaluation of the neck vessels with a 64-slice CT system using commercially available software. Eighteen patients had a low-dose NECT scan before CTA, and 18 patients had an LVCT scan after CTA. Subtraction quality for vascular segments was evaluated independently by 2 examiners. Cohen's Kappa was applied to evaluate interobserver reliability, and Wilcoxon signed rank test was used to test for differences between the 2 groups. Motion between the 2 scans was measured and correlated to image quality.
BSCTA using both NECT and LVCT scans as masks was successfully applied in all patients. Image quality did not differ significantly between the 2 groups, and interobserver agreement was high (k 0.5-1). Motion between the scans was highest for the jaw and hyoid, and lowest for the upper and lower spine. Decreased image quality on the subtracted images was associated with increased motion for the external carotid and vertebral artery, independent of mask type (P = 0.002-0.04).
BSCTA techniques can be successfully applied in the neck. If parenchymal phase imaging is indicated, the LVCT can be used as a bone subtraction mask and diagnostic scan, eg, for tumor imaging.
Investigative Radiology 02/2008; 43(1):27-32. · 4.59 Impact Factor
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ABSTRACT: A number of clinical situations exist in which high-resolution depiction of the external carotid artery system is required, a task not previously addressed by MR angiography. The purpose of this study was to evaluate the extent to which high-spatial-resolution MR angiography at 3 T can be used to map the normal external carotid artery system.
Twenty-three consenting adult patients were prospectively evaluated. Images acquired were evaluated by two independent observers, and each branch vessel was scored with regard to image quality, presence and grade of stenoses, and artifacts. Interobserver agreement regarding image quality and the presence and degree of stenosis was tested using the kappa coefficient. Differences in quality ratings between the two observers were assessed using the paired Student's t test.
Of 828 vessels analyzed, 92.63% were designated of diagnostic quality with no significant difference between the observers' image quality scores (p = 0.63). Good agreement was determined regarding image quality achieved (kappa = 0.716). All examinations were free of artifact sufficient to interfere with confident interpretation. Excellent correlation was seen with regard to stenosis detection and grading (kappa = 0.857). Of the external carotid artery systems assessed, 82.6% showed conventional anatomic vascular branching.
High-spatial-resolution, 3D contrast-enhanced MR angiography at 3 T using sagittal source data acquisition and an advanced acceleration factor of 6 allows high-quality (92.63% of arterial segments) visualization of the external carotid artery system, with complete head and neck vascular coverage.
American Journal of Roentgenology 12/2007; 189(5):1088-94. · 2.78 Impact Factor
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ABSTRACT: To assess the incremental diagnostic value of time-resolved three-dimensional (3D) magnetic resonance (MR) angiography over single-phase 3D MR angiography and cine MR imaging in juvenile and adult patients with congenital heart disease (CHD).
The study was HIPAA compliant and was approved by the institutional review board. Written informed consent was obtained from each patient. Eighty-one consecutive patients (46 male and 35 female patients; mean age, 31.1 years +/- 13.5 [standard deviation]) with CHD were examined with a 1.5-T MR imaging unit. The imaging protocol comprised time-resolved MR angiography (repetition time msec/echo time msec, 2.01/0.81) after injection of 0.03 mmol gadodiamide per kilogram of body weight at 4 mL/sec and single-phase high-spatial-resolution MR angiography (2.87/0.97) after injection of 0.15 mmol/kg gadodiamide at 1.5 mL/sec. After review of the time-resolved and conventional MR angiographic data sets, each of two independent observers listed the additional clinical information gained from time-resolved MR angiographic data. A Wilcoxon signed rank test was used to test for statistical differences between the image quality ratings of the two observers.
Time-resolved and single-phase high-spatial-resolution MR angiography yielded diagnostic image data in all patients. Observers 1 and 2 found functional information in time-resolved MR angiographic series in 52 and 51 patients, respectively, that was not seen at high-spatial-resolution MR angiography. Intra- and extracardiac shunts, respectively, were exclusively depicted by time-resolved MR angiography for observer 1 in 18 and two patients and for observer 2 in 15 and two patients. However, both observers reported higher confidence in the assessment of such smaller vascular structures as supraaortic vessels (in 12 patients for observer 1 and 11 patients for observer 2) and major aortopulmonary collateral arteries (in eight patients for observer 1 and 10 patients for observer 2) at high-spatial-resolution MR angiography. No significant difference was evident in image quality scoring between the two observers (P = .32 for time-resolved and P = .47 for conventional MR angiography).
Compared with conventional MR angiography, time-resolved MR angiography yields clinically relevant information in a substantial number of patients; hence, the two techniques should be regarded as complementary.
Radiology 09/2007; 244(2):399-410. · 5.73 Impact Factor
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ABSTRACT: Evaluation of coronary arteries at higher heart rates and in the presence of coronary stents remains problematic. The utilization of dual source computed tomography (DSCT) might improve the visualization of the coronary arteries under these conditions by imaging at a temporal resolution of 83 milliseconds, independent of heart rate.
Vessel phantoms (diameter 2-4 mm) were attached to a robotic device to simulate cardiac motion and scanned with a DSCT system. The phantoms had either inserts leading to 50% stenosis or carried stents. Images were evaluated for motion artifacts and measurements of the normal, stenotic, and in-stent lumen at different heart rates (50-120 bpm) were performed. Quantile regression analysis was performed to investigate heart rate dependence of the measurement errors.
Visualization of the stenoses and stents was possible without motion artifacts at heart rates of up to 120 bpm. Image quality was similar for the static (0 bpm) and the dynamic (50-120 bpm) scans. Errors for diameter measurements of the vessel lumen and the stenotic lumen were low (3-mm vessel: 1-2%), but considerable for in-stent diameter measurements (3-mm stent: 27-32%). A window/level setting of 1500/300 Hounsfield units was more favorable for stent evaluation. No heart rate dependence was found.
Depiction of coronary stents with DSCT is possible across a large range of simulated heart rates without motion artifacts and with image quality superior to that of previous generations of CT scanners.
Investigative Radiology 08/2007; 42(7):536-41. · 4.59 Impact Factor
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ABSTRACT: The aim of the study was to evaluate the utility of dark-lumen MR colonography (MRC) for the assessment of extra-colonic organs. Three hundred seventy-five subjects with suspected colonic disease underwent a complete MRC examination. MRC data were evaluated by two radiologists in a blinded fashion. In addition to the large bowel, the extra-intestinal organs from the lung bases to the pelvis were assessed for the presence of pathologies. All findings were divided into known or unknown findings and therapeutically relevant or irrelevant findings. If deemed necessary, other diagnostic imaging tests to further assess those findings were performed. In total, 510 extra-colonic findings were found in 260 (69%) of the 375 subjects. Known extra-colonic findings were found in 140 subjects (54%) and unknown findings in 120 subjects (46%). Thirty-one (12%) of the 260 subjects had therapeutically relevant findings (45 findings); 229 patients (88%) had irrelevant findings (465 findings). Dark-lumen MRC is a useful tool not only for the assessment of the entire colon, but also for the evaluation of extra-colonic organs. Thus, intra- and extra-colonic pathologies can be diagnosed within the same examination.
European Radiology 07/2007; 17(6):1574-83. · 3.22 Impact Factor
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ABSTRACT: To prospectively evaluate the feasibility of postoperative contrast enhanced Multi-detector-CT cholangiography (ceMDCT-CA) in living liver donors and transplant recipients.
Fifteen donors and 11 recipients of a right hepatic lobe underwent ceMDCT-CA. Six donors were admitted to exclude biliary leakage; 9 donors and 11 recipients were examined to exclude postoperative biliary obstruction. The examination protocol included the intravenous short-infusion of 100 mL of a biliary contrast agent. CT cholangiography data was acquired with a slice thickness of 1 mm. This scan was followed by examination of the upper abdomen in a venous phase. Data sets were evaluated quantitatively by measurement of the biliary opacification, and qualitatively on the basis of a scale ranging from 1 (non-diagnostic) to 4 (excellent). Opacification was correlated with postoperative serum bilirubin level.
CT data provided diagnostic delineation of the biliary tree in all 15 donors and seven of 11 recipients; in 4 recipients the degree of biliary opacification was non-diagnostic. Biliary opacification was generally higher in the donor collective. Four donors and 3 recipients presented a moderate focal biliary constriction without elevation of laboratory values. Six patients showed postoperative fluid collections suggestive of perihepatic biloma, however no biliary fistula could be visualized.
CeMDCT-CA represents a promising tool to non-invasively assess the postoperative biliary morphology in living liver donors and transplant recipients.
Hepato-gastroenterology 07/2007; 54(76):1176-80. · 0.66 Impact Factor
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ABSTRACT: To evaluate the technical feasibility of high spatial resolution contrast-enhanced magnetic resonance angiography (CE-MRA) with highly accelerated parallel acquisition at 3.0 T using a 32-channel phased array coil, and a high relaxivity contrast agent.
Ten adult healthy volunteers (5 men, 5 women, aged 21-66 years) underwent high spatial resolution CE-MRA of the pulmonary circulation. Imaging was performed at 3 T using a 32-channel phase array coil. After intravenous injection of 1 mL of gadobenate dimeglumine (Gd-BOPTA) at 1.5 mL/s, a timing bolus was used to measure the transit time from the arm vein to the main pulmonary artery. Subsequently following intravenous injection of 0.1 mmol/kg of Gd-BOPTA at the same rate, isotropic high spatial resolution data sets (1 x 1 x 1 mm3) CE-MRA of the entire pulmonary circulation were acquired using a fast gradient-recalled echo sequence (TR/TE 3/1.2 milliseconds, FA 18 degrees) and highly accelerated parallel acquisition (GRAPPA x 6) during a 20-second breath hold. The presence of artifact, noise, and image quality of the pulmonary arterial segments were evaluated independently by 2 radiologists. Phantom measurements were performed to assess the signal-to-noise ratio (SNR). Statistical analysis of data was performed by using Wilcoxon rank sum test and 2-sample Student t test. The interobserver variability was tested by kappa coefficient.
All studies were of diagnostic quality as determined by both observers. The pulmonary arteries were routinely identified up to fifth-order branches, with definition in the diagnostic range and excellent interobserver agreement (kappa = 0.84, 95% confidence interval 0.77-0.90). Phantom measurements showed significantly lower SNR (P < 0.01) using GRAPPA (17.3 +/- 18.8) compared with measurements without parallel acquisition (58 +/- 49.4).
The described 3 T CE-MRA protocol in addition to high T1 relaxivity of Gd-BOPTA provides sufficient SNR to support highly accelerated parallel acquisition (GRAPPA x 6), resulting in acquisition of isotopic (1 x 1 x 1 mm3) voxels over the entire pulmonary circulation in 20 seconds.
Investigative Radiology 06/2007; 42(6):392-8. · 4.59 Impact Factor
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ABSTRACT: During the past decade, technical improvements and numerous advances in scanner hardware and software have significantly improved image quality, speed, and reliability of 3-dimensional (3-D) contrast-enhanced magnetic resonance angiography (CE-MRA). The accuracy of CE-MRA is now comparable with that of computed tomography angiography or even conventional catheter angiography. Peripheral vascular disease (PVD) accounts for 50,000 to 60,000 cases of percutaneous transluminal angioplasty and for about 100,000 cases of amputation annually in the United States. Proper treatment of the arterial disease requires a comprehensive assessment of the underlying vascular morphology because it is crucial to localize and gauge the severity of arterial lesions for further therapeutic decision making.Contrast-enhanced magnetic resonance angiography has been widely implemented in noninvasive evaluation of PVD with high diagnostic accuracy. The lack of ionizing radiation and the use of contrast agent with relatively small potential nephrotoxicity in population of PVD with high prevalence of renal impairment are the appealing features for broad acceptance of CE-MRA in initial diagnosis and repeated follow-up studies of patients with PVD. The minimum anatomical coverage for evaluation of PVD comprises the aortic bifurcation to the ankles; however, because of the systemic nature of atherosclerosis hypertension, renal or cerebrovascular disease frequently coexist. Thus, many clinicians regard evaluation of the whole-body arterial vasculature as desirable.
Topics in Magnetic Resonance Imaging 05/2007; 18(2):127-34.
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ABSTRACT: The purpose of this HIPAA-compliant study was to prospectively evaluate the technical feasibility of a multistation high-spatial-resolution whole-body magnetic resonance (MR) angiography protocol in which high-acceleration parallel imaging (with acceleration factors of three and four) is performed with a 32-channel 3.0-T MR system. After institutional review board approval and written informed consent were obtained, 10 healthy volunteers (four men and six women aged 23-68 years) and four patients (two men and two women aged 56-79 years) suspected of having peripheral vascular disease underwent multistation whole-body contrast material-enhanced MR angiography. Use of multiarray surface coil technology and highly accelerated generalized autocalibrating partially parallel acquisition enabled the acquisition of isotropic high-spatial-resolution three-dimensional data sets for multiple stations. Two radiologists independently evaluated arterial image quality and presence of arterial stenoses. All examinations yielded good or excellent image quality. Interobserver agreement was excellent (kappa = 0.92; 95% confidence interval: 0.86, 0.96). Multistation whole-body MR angiography with high-acceleration parallel acquisition is feasible at 3.0 T. Further clinical studies combined with ongoing optimization of radiofrequency systems and coils seem warranted to advance the potential of this technology.
Radiology 04/2007; 242(3):865-72. · 5.73 Impact Factor
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ABSTRACT: The objective of our study was to investigate a multistation whole-body MR angiography (MRA) protocol using a 32-channel MR system with multicoil technology in a population of patients with suspected peripheral vascular disease (PVD).
Fifty consecutive patients with suspected PVD (31 men, 19 women; age range, 46-91 years) underwent multistation whole-body contrast-enhanced MR angiography (CE-MRA) on a 32-channel 1.5-T MR system equipped with multicoil technology. A two-step contrast injection protocol was used: After the first injection, images of the most proximal station (station I, head and neck) were acquired, followed by the most distal station (station IV, calves). Images of the intermediate two stations (station II, chest and abdomen; station III, pelvis and thighs) were acquired during the second injection. Conventional catheter angiography was performed for symptomatic vascular regions in 30 patients. The image quality of the arterial segments and the presence and degree of the arterial stenosis were evaluated by two radiologists. The interobserver variability was calculated by kappa statistics, and comparative analysis between CE-MRA and catheter angiography was performed by means of the Spearman's rank correlation coefficient.
Most of the vascular segments (1,912/1,976 [97%]) were visualized on wholebody CE-MRA with diagnostic image quality. Significant arterial disease (> or = 50%) was detected in 167 (observer 1) and 177 (observer 2) segments with excellent interobserver agreement (kappa = 0.84). There was a significant correlation between CE-MRA and conventional angiography for the degree of stenosis (R = 0.92 and 0.89 for observers 1 and 2, respectively). The sensitivity and specificity of CE-MRA for the detection of arterial stenoses 50% or greater were 92% and 96% for observer 1 and 93% and 97% for observer 2, respectively, compared with those of conventional angiography.
Using a multichannel radiofrequency system with multicoil technology, the whole-body CE-MRA approach outlined in this article is able to provide high-spatial-resolution data sets with high diagnostic image quality for evaluation of arterial occlusive disease in most vascular territories.
American Journal of Roentgenology 03/2007; 188(2):529-39. · 2.78 Impact Factor
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Fritz K W Schaefer,
Philipp J Schaefer,
Christian Altjohann,
Michael Bourne,
Francesco Decobelli,
Mathias Goyen,
Paul D Griffiths,
Lars Kopka,
Karl F Kreitner,
Johann Link, [......],
Christiane Pering,
Christiane Poeckler-Schoeninger, Stefan G Ruehm,
Mansur R Sachoran,
Gernot Schulte-Altedorneburg,
Oliver S Springer,
Paul Steiner,
Alexander Wall,
Jan Winterer,
Bernd Tombach
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ABSTRACT: Prospective evaluation of diagnostic accuracy of single field-of-view contrast-enhanced MR Angiography (ceMRA) with 1.0M gadobutrol compared to intraarterial DSA in body arteries.
In an European multicenter study 179 patients underwent ceMRA and DSA. For each indication five prospectively defined vessel segments were evaluated by local investigators onsite and by three site-independent blinded readers (BR) independently.
The agreement between ceMRA and DSA diagnosis was statistically significant in the onsite (96.6%) and blinded reader (86.6-90.2%) evaluation. Sensitivity, specificity, accuracy, positive (PPV) and negative predictive values (NPV) for detection of relevant stenosis (>50%) were calculated for the right and left internal carotid arteries, and common and external iliac arteries: Sensitivity was 95-98% (onsite) and 76-96% (BR), specificity 94-96% (onsite) and 86-94% (BR), accuracy 96% (onsite) and 87-93% (BR), NPV 98-99% (onsite) and 84-98% (BR), and PPV 79-93% (onsite) and 44-91% (BR), respectively.
CeMRA of body arteries using 1.0M gadobutrol provides diagnostic information comparable to intraarterial DSA.
European Journal of Radiology 02/2007; 61(2):315-23. · 2.61 Impact Factor
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ABSTRACT: To investigate the dependence of semiquantitative renal perfusion parameters on the acquisition technique and field strength used.
After intravenous injection of 7-mL Gd-chelates, high-temporal-resolution turbo fast low-angle shot (TurboFLASH) renal perfusion measurements were performed on eight healthy volunteers at 1.5T and another eight healthy volunteers at 3.0T. Another eight healthy volunteers were examined at 3.0T using time-resolved echo-shared angiographic technique (TREAT) after bolus administration of 7-mL Gd-chelates with a temporal resolution of 1.4 seconds. Analysis of the first-pass perfusion data yielded the following semiquantitative renal perfusion indices: mean transit time (MTT), time to peak (TTP), maximal upslope (MUS), and maximal signal intensity (MSI).
MTT and TTP did not show significant differences between the different techniques. MSI and MUS were significantly (P < or = 0.002) higher with TREAT (591.1 a.u./second and 103.5 a.u./second) than with TurboFLASH at both field strengths (1.5T: 400.5 a.u./second and 65.4 a.u./second; 3.0T: 362.2 a.u./second and 68.7 a.u./second).
Semiquantitative renal perfusion measurements are feasible with time-resolved echo-shared sequences and TurboFLASH techniques. While MTT and TTP appear to be independent of the technique and field strength applied, MUS and MSI are higher with TREAT.
Journal of Magnetic Resonance Imaging 01/2007; 24(6):1413-9. · 2.70 Impact Factor
