共查询到20条相似文献,搜索用时 31 毫秒
1.
Molecular MR imaging of human thrombi in a swine model of pulmonary embolism using a fibrin-specific contrast agent 总被引:2,自引:0,他引:2
Spuentrup E Katoh M Buecker A Fausten B Wiethoff AJ Wildberger JE Haage P Parsons EC Botnar RM Graham PB Vettelschoss M Günther RW 《Investigative radiology》2007,42(8):586-595
OBJECTIVE: Molecular targeted MR imaging of human clots material in a model of pulmonary embolism using a fibrin-specific magnetic resonance imaging contrast agent (EP-2104R, EPIX Pharmaceuticals, Cambridge, MA). MATERIAL AND METHODS: Fresh ex vivo engineered thrombi (human blood) and human clots removed from patients were delivered in 11 swine. Molecular MR imaging with a 3D gradient-echo [3D fast field echo (3DFFE)] sequence and a navigator-gated and cardiac-triggered 3D inversion-recovery black-blood gradient-echo sequence (IR) was performed before thrombus delivery, after thrombus delivery but before contrast media application, and 2 hours after i.v. administration of 4 micromol/kg EP-2104R. MR images were analyzed by 2 investigators and contrast-to-noise ratio (CNR) was assessed. Thrombi were removed for assessment of gadolinium (Gd) concentration. RESULTS: Only after contrast media application were pulmonary emboli [freshly engineered thrombi (n = 23) and human clot material removed from patients (n = 25)] visualized as white foci on MR images. CNR was 13 +/- 3 (ex vivo engineered clot) and 22 +/- 9 (patient clot material) for the fast field echo (FFE)-sequence and 29 +/- 9 (ex vivo engineered clot) and 43 +/- 18 (patient clot material) for the IR-sequence, respectively. A high Gd concentration in the clots was found (82 +/- 43 microM for the freshly engineered and 247 +/- 44 microM for the clots removed from patients, respectively). CONCLUSIONS: EP-2104R allows for molecular MR imaging of human clot material in the pulmonary vessels of a swine model. 相似文献
2.
C J Fretz D D Stark C E Metz G Elizondo R Weissleder J H Shen J Wittenberg J Simeone J T Ferrucci 《AJR. American journal of roentgenology》1990,155(4):763-770
Diagnostic accuracy of contrast-enhanced CT, unenhanced MR imaging, and MR images enhanced with superparamagnetic iron oxide was evaluated in 10 patients with histologically proved hepatic metastases. First, diagnostic performance of the imaging technique with respect to the ability of radiologists to recognize the presence or absence of a metastasis was measured by using receiver-operating-characteristic (ROC) analysis of single images. Second, the total number of lesions (N = 108) detected by "complete" CT and MR examinations was counted. Finally, lesion-liver contrast-to-noise ratios (CNR) were measured in all MR sequences. The area under the ROC curve was .67 +/- .03 for contrast-enhanced CT, .81 +/- .07 for the unenhanced SE 260/14 sequence, and .92 +/- .01 for the iron oxide-enhanced SE 1500/40 sequence. The enhanced SE 1500/40 sequence yielded significantly (p less than .005) greater accuracy than did contrast-enhanced CT. The same sequence detected significantly (p less than .05) more lesions than all other imaging techniques (19% more than the best unenhanced MR sequence and 36% more than contrast-enhanced CT). The enhanced SE 1500/40 sequence also yielded the highest CNR value (19.5 +/- 10.2) of all MR sequences. These results indicate that iron oxide-enhanced MR imaging is a superior imaging technique for the detection of hepatic lesions. 相似文献
3.
K C Seelos G R Caputo C L Carrol H Hricak C B Higgins 《Journal of computer assisted tomography》1992,16(2):169-175
Spin echo MR imaging has not permitted reliable differentiation between intraluminal blood clot and tumor thrombus. This study assessed the role of ECG referenced repetitive gradient refocused echo (cine GRE) imaging for the differentiation of intravascular tumor from blood clot. Cine GRE images were reviewed in 23 patients, 11 of whom had intravascular tumor and 12 of whom had intravascular blood clots. Percentage contrast between the lesion and skeletal muscle as the reference tissue was determined from a subjective review of the images and objective signal intensity measurements. Intravascular clots were found to be lower in signal intensity than muscle (mean -55 +/- 29%). Intravascular tumors showed higher signal intensity relative to muscle (mean +17 +/- 9%) with the exception of myxomas (n = 2), which had signal intensity values relative to muscle as low as clots (mean -41 +/- 17%). Three masses in the inferior vena cava were composed of central tumor and peripheral clot; the two components could be differentiated with cine GRE imaging. Cine GRE imaging provides adequate signal intensity differences to visualize intravascular masses and helps to differentiate intravascular clot from tumor thrombus. However, if the tumor contains substantial amounts of iron, then the signal is also low and consequently clot and thrombus may not be distinguishable. This can occur in some atrial myxomas. 相似文献
4.
Zheng J Li D Maggioni F Abendschein D Simonetti O Laub G Finn JP Gropler RJ Cavagna FM 《Investigative radiology》2005,40(9):604-613
OBJECTIVE: The objective of this study was to evaluate a new blood pool contrast agent, B-22956, for detecting myocardial perfusion abnormality and coronary artery stenosis by magnetic resonance imaging (MRI) in 1 setting. MATERIALS AND METHODS: Coronary artery atherosclerotic stenoses were created in 6 miniswine. Myocardial first-pass perfusion imaging was performed with a bolus injection of 0.015 mmol/kg B-22956 during pharmacologic stress followed by postcontrast coronary artery imaging after another injection of B-22956/1. The total doses for the 6 pigs were 0.1 mmol/kg (n=3) and 0.15 mmol/kg (n=3). Perfusion upslope maps were analyzed and MR coronary artery images were reviewed by 2 readers. RESULTS: For all 6 pigs, the normalized upslopes of the perfusion curves were 0.83+/-0.12, 0.74+/-0.15, and 0.52+/-0.05 (P<0.01 vs. normal) with normal or mild (<50% area stenosis), moderate (<50% and <75%), and severe stenosis (>75%), respectively. Mean signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) in right coronary artery images improved 90% and 200%, respectively, with a total dose of 0.1 mmol/kg of B-22956. Excellent agreements (kappa=0.82) were achieved for evaluating the grade of stenosis between MR postcontrast coronary artery images and histopathology by 2 reviewers. CONCLUSION: The MR blood pool contrast agent B-22956 demonstrated the ability for detecting myocardial perfusion abnormalities and coronary artery stenosis in 1 setting. 相似文献
5.
Gradient-echo (GRE) and spin-echo (SE) magnetic resonance (MR) imaging was performed in 31 patients with chronic left ventricular (LV) thrombi. Thrombi were confirmed or excluded at surgery or by means of other corroborative diagnostic techniques. MR images were evaluated by three reviewers without knowledge of results of corroborative studies. Diagnoses were graded unequivocal if agreed on by three observers and probable if agreed on by two observers. With SE imaging, 12 of 18 confirmed thrombi were detected unequivocally, five were considered probable, and one was not detected. With GRE imaging, 16 of the 18 thrombi were visualized unequivocally; two were considered probable. With SE technique, thrombus was unequivocally excluded in nine of 13 cases and exclusion was considered probable in four. One finding was false-negative. Exclusion of thrombus with GRE imaging was unequivocal in 10 of 13 cases and probable in two, and one finding of thrombus was false-positive. GRE imaging resulted in improved differentiation of thrombi from the surrounding blood pool and myocardium and thus was diagnostically superior to SE imaging in detection of LV thrombi. 相似文献
6.
Five venous thrombi were induced in the external jugular veins of three laboratory dogs, and were repeatedly imaged over 3 weeks using a 0.35-T magnetic resonance (MR) imager. MR magnitude and phase images, T1 and T2 relaxation times, venography, and histologic sections of these thrombi were evaluated to determine the changes in appearance on MR images with time. Venous thrombi appeared hyperintense compared with muscle on both relatively T1- and T2-weighted spin-echo sequences regardless of the age of the clot. Organization of the thrombus beyond 1 week was manifested as increased prominence of flow signal void in and around the clot. Distinction between intraluminal thrombus and flow-related artifacts was aided by phase image reconstruction. Nineteen venous thrombi locations in 13 patients revealed an MR appearance similar to that of the experimental animal model. Three patients (six thrombi locations) had serial examinations over 4 weeks. No significant change in thrombus signal characteristics was noted with time. It is concluded that MR imaging at 0.35 T cannot be used to predict the age of thrombus (up to 3 weeks) but may be helpful in following its resolution. 相似文献
7.
Lower extremity deep venous thrombosis: evaluation with ferumoxytol-enhanced MR imaging and dual-contrast mechanism--preliminary experience 总被引:2,自引:0,他引:2
Li W Salanitri J Tutton S Dunkle EE Schneider JR Caprini JA Pierchala LN Jacobs PM Edelman RR 《Radiology》2007,242(3):873-881
Institutional review board approval and informed consent were obtained for this HIPAA-compliant study, whose purpose was to prospectively evaluate the use of a dual-contrast mechanism in conjunction with an iron oxide blood pool contrast agent, ferumoxytol, to depict deep venous thrombosis (DVT). Nine patients with lower extremity DVT detected with duplex ultrasonography (US) were imaged with magnetic resonance (MR) imaging and ferumoxytol. Three techniques, including precontrast two-dimensional time-of-flight (TOF) imaging, ferumoxytol-enhanced bright-blood imaging, and ferumoxytol-enhanced dark-blood imaging, were applied. Image quality for precontrast and ferumoxytol-enhanced images was analyzed by using a four-point scale. Thrombus was depicted as a filling defect within the blood pool on bright-blood images and as bright tissue that appeared highly contrasted against a dark background on dark-blood images. Image quality of ferumoxytol-enhanced images was uniformly superior to that of precontrast TOF images (P = .007). Compared with precontrast TOF images, ferumoxytol-enhanced bright-blood images had higher contrast-to-noise ratios (CNRs) between thrombus and blood (P = .051), whereas ferumoxytol-enhanced dark-blood images showed significantly higher CNRs between thrombus and surrounding muscle (P = .008). Ferumoxytol-enhanced MR imaging can depict DVT with a dual-contrast mechanism and show the extent of thrombus. 相似文献
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10.
J E Stuhlmuller T D Scholz J D Olson T L Burns D J Skorton 《Investigative radiology》1991,26(4):343-347
To optimize magnetic resonance (MR) methods of characterizing thrombi, further studies of biologic determinants of spinlattice (T1) and spin-spin (T2) relaxation times of thrombi are needed. As a step toward evaluating the influence of thrombus cellular composition on MR properties, the authors evaluated the effect of platelet depletion on MR relaxation times of in vitro blood clots. Blood from 13 fasting normal men was collected into sodium citrate (3.8%) and centrifuged ( [10,000 X g] X 5-10 minutes). Platelet-poor specimens (less than 20,000 per mm3) were reconstituted from the plasma and packed erythrocytes to match precentrifugation hematocrit levels. T1 and T2 measurements were made at 20 MHz within three to six hours of initiating clotting. The mean T1 value for platelet-rich (normal) specimens was 1117 +/- 86 mseconds versus 1119 +/- 68 mseconds for the platelet-poor specimens (P greater than .90). The mean T2 value for platelet-rich (normal) specimens was 616 +/- 130 mseconds versus 434 +/- 79 mseconds for the platelet-poor specimens (P less than .001). The mean water content in the platelet-rich (normal) specimens was 79.5% +/- 1.2% versus 80.0% +/- 1.2% in the platelet-poor specimens (P greater than .50). In summary, platelet depletion by buffy coat removal significantly shortens MR T2 values of in vitro clot. These data suggest that thrombus cellular composition, other than erythrocytes, alters MR relaxation times of clotted blood. 相似文献
11.
Infarcted myocardium in pigs: MR imaging enhanced with slow-interstitial-diffusion gadolinium compound P760. 总被引:1,自引:0,他引:1
PURPOSE: To assess the value of P760, a gadolinium chelate with slow interstitial diffusion and high relaxivity, for magnetic resonance (MR) imaging of acute myocardial infarction in pigs. MATERIALS AND METHODS: First-pass gradient-echo MR imaging and spin-echo MR imaging were performed with P760 and then with gadoterate meglumine in eight pigs with occlusive acute myocardial infarction. P760 signal intensity enhancement and clearance were compared with those of gadoterate meglumine. RESULTS: The first-pass enhancement ratio of P760 in normal myocardium was higher than that in infarcted myocardium (1.37 +/- 0.06 [SEM] vs 1.05 +/- 0.03, P = .03). The myocardial first pass showed a blood pool-like curve for P760. The blood pool enhancement ratio 40 seconds after injection was higher for P760 than for gadoterate meglumine (left ventricular cavity, 1.75 +/- 0.06 vs 1.45 +/- 0.06, P = .009). Spin-echo MR imaging showed improved contrast between normal and infarcted myocardium after P760 administration: The ratio before contrast material administration was 0.21 +/- 0.03, that at 15 minutes was 0.48 +/- 0.05 (P = .002), and that at 25 minutes was 0.47 +/- 0.07 (P = .003). CONCLUSION: P760 is an MR imaging contrast agent characterized by low diffusion, a blood pool effect soon after low-dose administration, and fast elimination. This agent is useful for improved myocardial perfusion MR imaging of acute myocardial infarction. 相似文献
12.
M B Hofman R E Henson S J Kovács S E Fischer R B Lauffer K Adzamli J De Becker S A Wickline C H Lorenz 《Magnetic resonance in medicine》1999,41(2):360-367
The ability of a blood pool contrast agent to enhance MR coronary angiography was defined. The proximal coronary vessels of pigs were imaged before and after administration of Gd-DTPA bound covalently to bovine serum albumin (0.2 mmol/ kg). The contrast agent resulted in a reduction of the blood T1 value to 33+/-5 msec, as determined in vivo with a Look-Locker technique. Both 2D and 3D imaging techniques were performed. An inversion pulse suppressed the signal of nonblood tissue postcontrast. After contrast agent administration, in the 3D data set the signal-to-noise ratio (SNR) of blood and contrast-to-noise ratio (CNR) of blood to myocardium were improved by factors of 2.0+/-0.2 and 15+/-8, respectively (P < 0.05). Postcontrast, the 3D acquisition was superior to the 2D technique in terms of spatial resolution, SNR of blood, and CNR of blood to myocardium. The high contrast of the 3D data set allowed for direct and rapid display of coronary arteries using a "closest vessel projection." 相似文献
13.
Introduction Diagnosis of cerebral sinus vein thrombosis is still a challenge for imaging. MRI and MRA play a major role in sinus imaging. For further development of MR techniques, MR-compatible animal models are required. The aim of this study was to develop an animal model for sinus thrombosis and additional cortical vein thrombosis with a clot of human blood for MR imaging studies.Methods A combined surgical and interventional approach was carried out in 13 pigs. After minimal invasive surgical access to the anterior superior sagittal sinus and cortical vein, thrombosis with human blood was induced using an interventional catheter approach. MR imaging was performed prior to and after thrombus induction.Results Sinus thrombosis was induced in 12 of 13 animals. Three animals suffered acute subdural haemorrhage; one of these animals died during the intervention, and one died after thrombus induction. MR imaging of the thrombosed sinus could easily be performed without significant artefacts in 11 of 13 animals.Conclusion This new model of sinus and cortical vein thrombosis with a clot of human blood allows artefact-free imaging studies on MR. 相似文献
14.
Magnetic resonance imaging of blood and clots in vitro 总被引:1,自引:0,他引:1
C C Blackmore C W Francis R G Bryant B Brenner V J Marder 《Investigative radiology》1990,25(12):1316-1324
The effects of variations in blood clot composition on magnetic relaxation rates and magnetic resonance (MR) image have been characterized in vitro. Both 1/T1 and 1/T2 were found to be linear functions of hematocrit for blood and clot, with increases in hematocrit resulting in progressive decreases in image signal intensity. Clot formation in fully oxygenated samples produced no change in relaxation rates or MR images compared with unclotted blood, but clot retraction was associated with a significant increase in 1/T2 that resulted in a decreased signal. Retraction resulted in a heterogenous image with appearance of a hypointense peripheral rim; differences in the method of clot preparation resulted in significant image inhomogeneity. The pattern of fibrinolysis was found to depend on the type of plasminogen activator used and its site of initial application. Injection of tissue plasminogen activator into the clot resulted in lysis, primarily in the clot interior, whereas placing the enzyme in the surrounding serum caused degradation from the outside of the clot. Both observations are consistent with the high binding affinity of tissue plasminogen activator for fibrin. By comparison, streptokinase, with low fibrin binding affinity, dissolved thrombi in a peripheral pattern whether injected into the thrombus or introduced in the serum. These findings identify several variables of clot composition and structure that influence MR images of thrombi and should be considered in their interpretation. 相似文献
15.
Improved MR coronary angiography with use of a new rapid clearance blood pool contrast agent in pigs 总被引:5,自引:0,他引:5
PURPOSE: To evaluate in an animal model the potential for clinical use of a new rapid clearance blood pool contrast agent to improve free-breathing and breath-hold magnetic resonance (MR) coronary angiography. MATERIALS AND METHODS: Free-breathing and breath-hold MR coronary angiography were performed in a pig model (n = 9) (a) without use of a contrast agent; (b) with P792 (Guerbet Research, Aulnay Sous Bois, France), a monodisperse monogadolinated macromolecular compound that acts as a blood pool contrast agent with rapid clearance properties; and (c) with an extravascular gadolinium-based contrast agent. This resulted in six imaging options, which were compared in terms of contrast-to-noise ratio (CNR), signal-to-noise ratio, and vessel length measurements by using the Student t test. RESULTS: Use of P792 improved CNR and visible vessel length significantly with both MR respiratory motion correction approaches, as compared with nonenhanced MR imaging (P <.05). CNR was improved by 76% (from 5.0 to 8.6) with the free-breathing approach and by 34% (from 6.2 to 8.2) with the breath-hold approach. Visible vessel length was increased by 27% (from 79.7 to 99.2 mm) with the free-breathing approach and by 90% (from 48.2 to 86.5 mm) with the breath-hold approach. The P792-enhanced free-breathing approach allowed more distal visualization of the coronary arteries than did the P792-enhanced breath-hold approach (P <.05). Use of the extravascular contrast agent did not improve image quality significantly when compared with that of nonenhanced MR images. CONCLUSION: Use of P792 improves coronary artery MR imaging in conjunction with free-breathing and breath-hold approaches. 相似文献
16.
This report demonstrates the capability of magnetic resonance imaging to determine the extent of inferior vena cava thrombi and to differentiate tumor thrombus from blood clot with the use of Gd-diethylenetriamine pentaacetic acid as a contrast agent. 相似文献
17.
L J Kroft J Doornbos S Benderbous A de Roos 《Journal of magnetic resonance imaging : JMRI》1999,9(6):777-785
Meglumine-carboxymethyldextran-ethylenediamino-gadoterate (CMD-A2-Gd-DOTA) was evaluated as a blood pool contrast agent for magnetic resonance angiography (MRA). MRA of large body vasculature was performed in seven pigs using a gradient-echo sequence at 1.5 T before and after 0.05 mmol/kg CMD-A2-Gd-DOTA injection. The signal- and contrast-to-noise ratios (SNRs, CNRs) were measured, as well as the pharmacokinetic clearance pattern. CMD-A2-Gd-DOTA visualized the vasculature with a high SNR and CNR for over 110 minutes after injection, but for the renal arteries the CNR was only significant within 15 minutes. Image quality was maximum within 15 minutes, producing enhancement (mean +/- SD) as follows: aortic arch 738 +/- 272%, abdominal aorta 393 +/- 123%, left renal artery 202 +/- 95%, right renal artery 248 +/- 107%, inferior vena cava 371 +/- 129%, and portal vein 513 +/- 145%, all P values < or =0.001. The clearance pattern was triphasic. Due to the excellent enhancement of vasculature without background enhancement, CMD-A2-Gd-DOTA is potentially a useful MR blood pool contrast agent for equilibrium phase MRA. 相似文献
18.
The performance of hepatocyte-targeted magnetic resonance (MR) contrast agents in the detection of liver tumor was tested in rats with hepatitis. Hepatocyte-targeted MR contrast agents (paramagnetic hepatobiliary complex [manganese-DPDP] and superparamagnetic iron oxide coated with arabinogalactan [SPIO-AG]) were injected into normal rats and rats with carbon tetrachloride-induced hepatitis. Before and after injection of either contrast agent, ex vivo relaxometry (0.94T) or in vivo MR imaging (1.0T) were performed. The obtained liver and tumor T1 and T2 relaxation times, liver and tumor signal-to-noise ratios (SNR), and tumor-liver contrast-to-noise ratios (CNR) of control rats and rats with hepatitis were compared. Both relaxometry and MR imaging showed that MnDPDP and SPIO-AG selectively enhanced liver tissue in controls and in rats with hepatitis to the same degree, and little tumor enhancement was seen in either group. As a result, no significant difference between control rats and rats with hepatitis was observed in the postcontrast tumor-liver CNR. For a MnDPDP-enhanced CNR with spin echo (SE) of 310/15, the results were -10.4+/-3.6 in control rats vs. -11.5+/-1.4 in rats with hepatitis; for a SPIO-AG-enhanced CNR with SE 2000/45 and 2000/90, respectively, the results were 30.7+/-9.2 and 18.7+/-4.7 in control rats vs. 31.9+/-7.1 and 17.7+/-2.4 in rats with hepatitis. These results indicate that hepatocyte-targeted contrast agents effectively enhance liver tissue and enhance liver-tumor image contrast despite hepatocellular dysfunction. 相似文献
19.
菲立磁增强MRI对局灶性肝病的诊断价值:与螺旋CT对比的ROC曲线分析 总被引:2,自引:0,他引:2
目的 :对比分析菲立磁增强扫描与螺旋CT增强扫描对局灶性肝病的诊断价值。方法 :收集经本院完成螺旋CT增强扫描及菲立磁增强MRI扫描且临床、手术病理证实局灶性肝病 2 6例 5 7个病灶 ,采用分组盲法ROC曲线分析对比评价菲立磁增强MRI与螺旋CT增强扫描对局灶性肝病的诊断价值。结果 :联合分析平扫 +菲立磁增强MRI对病灶检出最好 ,与其它三组比较有显著性差异。对病灶定性 ,平扫 +菲立磁增强MRI组ROC曲线下面积Az 值最大为 0 92 6 0 ,准确性为 86 .8% ,差异有显著性 ,P <0 .0 5。螺旋CT增强扫描、MRI平扫及单独分析菲立磁MRI等三种方法之间差异无显著性 (P >0 .0 5 )。结论 :菲立磁增强MRI肝成像无论病灶的检出及定性诊断价值均高于螺旋CT增强扫描。联合分析平扫+菲立磁MRI较单独分析SPIO能明显改善病灶的检出能力及定性诊断能力。 相似文献
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