BACKGROUND: The MRJ studies of acute myocardial infarction (AMI)were more frequently focused on the changes of myocardial perfusion. OBJECTIVE: To investigate the characteristics of infarction and myocardial reperfusion in MRI, and make comparison of them with the results of their staining pathologic sections. DESIGN: Completely randomized grouping design and randomized controlled study. SETTING: Magnetic Resonance Department of Air-force General Hospital of Chinese PLA and Radiological Department of General Hospital of Chinese PLA. MATERIALS: The experiment was completed in the Medical Animal Experimental Center, General Hospital of Chinese PLA in December 2003.Fourteen miniature pigs were divided into 2 groups: infarction group and reperfusion group with 7 pigs in each group. One-month before and after the operation, MRI was performed in order to strengthen the scanning examination. One-month after operation, axial plane pathologic slices, which were corresponding to the MRI, were given TTC and SE staining. According to the TTC staining results, samples of the infarcted myocardium (corresponding to the anterior wall of the left ventricular) and normal myocardium (corresponding to the posterior wall of the left ventricular) were taken and given HE staining to observe the extent of infracted myocardium. MAIN OUTCOME MEASURES: The changes in cardiac shape and function and the changes of myocardial T1 and T2 relaxation time. RESULTS: Fourteen Chinese miniature pigs were used with 7 in each group. ①Relaxation time of T1 and T2 of infarcted myocardium in infarction group was obviously longer than that of thenormal myocardium [1 159.54±78.67, (60.15±6.31) ms, 1 056.15±70.95, (47.46±7.94) ms, t=2.63,5.38, P＜ 0.05, 0.01] and that of the infarcted myocardium in reperfusion group was also obviously longer than that of normal myocardium [1 171.14±139.98,(56.64±6.16) ms, 1 074.64±97.61, (44.57±4.25) ms, t=2.64, 6.24, P ＜ 0.05,0.01].②MRI in single infracted myocardium and reperfused infracted myocardium was both changed obviously,but without significant differences in relaxation time and stress.Dilatation of left ventricle in single infracted group was more obviously than that in the reperfusion infracted group.③Theresult of MRI was coincidence with that examinated with TTC staining CONCLUSION:①MRI is a useful imaging modality in the evaluation of AMI and the left ventricle remodeling after myocardial infarction.②It is significant for reperfusion to treat remodeling of left ventricle after acute myocardium infarction.③There is good correlation between MRI and pathological examination.

Objective To compare the accuracy of CE MRA and Gated 2D TOF MRA in evaluation of internal carotid artery stenosis. Methods 34 patients (male 27, female 7, age range 45-78 years) were evaluated with contrast enhanced three dimensional magnetic resonance angiography (CE MRA) and unenhanced ECG gated two dimensional time of flight MRA (Gated 2D TOF MRA). Digital subtraction angiography (DSA) was used as the “gold standard”. The MRA images were reprojected with maximum intensity projection (MIP) algorithm. Sensitivity, specificity, diagnositic accuracy,overestimation and underestimation were assessed. Results (1) DSA provided 68 diagnostic judgments: 23 were negatives and 45 were positives (mild stenosis 10, moderate stenosis 14, severe stenosis 17, occlusion 4). CE MRA was in agreement with angiography in 66 (97%), but overestimation resulted in 2 cases. Gated 2D TOF MRA was in agreement with angiography in 56 (82%), with 9 overestimation and 3 underestimation. (2) Taking negative and positive cases as judgement, CE MRA showed higher sensitivity, specificity, and diagnostic accuracy than Gated 2D TOF MRA (100% versus 95 6%, 100% versus 78.3%, 100% versus 89.4%, respectively). (3) Taking 70% stenosis as judgement, CE MRA also showed higher sensitivity, specificity, and diagnostic accuracy than Gated 2D TOF MRA (100% versus 95 2%, 97.8% versus 93.6%, 98.5% versus 94.1%, respectively). Gated 2D TOF MRA vs DSA, CE MRA vs DSA and Gated 2D TOF MRA vs CE MRA all had no significant difference (? 2=3.000 with P =0.083, ? 2=2.000 with P =0.157, and ? 2=1.600 with P =0.206 respectively) Conclusion Compared with Gated 2D TOF MRA,CE MRA is more accurate in evaluation of carotid artery stenosis.

Objective To describe the MR imaging features and pathologic findings of hepatic angiomyolipoma (HAML), and to evaluate the utility of MR imaging in diagnosis of this tumor. Methods The MR imaging features of eight patients with HAMLs confirmed pathologically were analyzed retrospectively and correlated with pathologic findings. Results Eight patients had a solitary hepatic mass, five (mixed type HAML) of which were diagnosed correctly, and two (1 myomatous type HAML and 1 angiomatous type HAML) of which were diagnosed as hepatic adenoma and focal nodular hyperplasia, and one (mixed type HAML) with hemorrhage and multiple cystic change was mistaken for malignant tumor. Six cases of mixed type HAML exhibited heterogeneously high signal intensity on T 1 and T 2WI. The high signal intensity on T 1WI in five cases disappeared completely after using fat saturation, and most part of the high signal intensity in one case disappeared and some of the high signal intensity remained unchanged after using fat saturation, and multiple cystic change within this mass was detected. One myomatous type HAML and one angiomatous type HAML showed hypointensity on T 1WI and hyperintensity on T 2WI. Multiphase dynamic Gd DTPA enhanced MR scanning was performed in six patients and all those masses showed strong enhancement during arterial phase, and four of which showed moderate enhancement and two slight enhancement during portal venous and delayed phase. Pseudocapsule detected in five cases showed slight enhancement on portal venous and (or) delayed phase. Conclusion MR imaging can reveal the characteristic findings of mixed type HAML and accurate preoperative diagnosis can be made.

AIM To examine the effect of metabotropic glutamate receptor ligand (s) 4 carboxy 3 hydroxyphenyl glycine 〔(s) 4C3HPG〕 on kainic acid induced epileptic seizures and brain damage in rats. METHODS Rats were given (s) 4C3HPG (500 nmol/rat) by icv infusion prior to kainic acid (KA) injection ip(10 mg?kg -1 ). The behavoir changes, electrographic seizure duration and histological alterations between different group of rats were compared. RESULTS (s) 4C3HPG markedly reduced seizures severity in response to kainate. The seizure score in the rat with (s) 4C3HPG injection icv was significantly lower than that of control during the first three hours observation period after KA administration ( P

Objective To evaluate the clinical value of MR spectroscopy in intracranial neoplasm. Methods 52 cases with brain neoplasm or recurrent neoplasm or non-tumor lesion confirmed by pathology were undergone proton MRS before stereotactic biopsy, or operation. Results Of 52 cases, 38 were neoplasm and 14 were nonneoplastic lesion, 34 of 38 brain tumor, 11 of 14 nonneoplastic lesion were diagnosed correctly. The characteristics on MRS of glioma were remarkable Cho increase and NAA decrease, Lac in the tumors and the central necrotic area was elevated. Metastasis: Cho increased,NAA disappeared or obviously decreased and Lac increased, but the peritumoral region was normal. Lymphoma: Cho increased, NAA decreased moderately, Lip presented, but the peritumoral region was normal. Demyelination lesion: slight or median decreased NAA and normal Cr, Lac increased slightly. All metabolism decreased or disappeared in radiation necrosis, Cho was relative high compared with NAA. Brain abscess: Lac increased in the centre of abscess and perilesion was normal.Conclusion MRS has significant value in detecting and differentiating brain lesions.

Objective To develop a localization strategy for magnetic resonance coronary angiography (MRCA). Methods In 89 subjects, the standard 4-chamber view and long-axis view of left and right ventricle were acquired using Fast-Imaging-Employing-Steady-State-Acquisition (FIESTA) sequence in CINE mode, and the trigger-delay time for mid-diastolic phase was determined. Coronary vessels including right coronary artery (RCA), left main (LM), left anterior descending (LAD), and left circumflex (LCX) were localized and imaged using 3-dimensional fat-suppressed FIESTA sequence during end-expiration. The reproducibility of the localization strategy was evaluated by taking the standard of coronary segmentation system recommended by American Heart Association. Results Eighty-six subjects completed the examination with full respiratory co-operation and the indication ratio was 96.63%. Nine planes were optimized as the standard to target the main branches of coronary arteries, and a comprehensive reproducibility reached 100% in demonstrating the proximal and middle segment of RCA (AHA-18, 19), LM (AHA-1, 2), proximal and middle segment of LAD (AHA-3, 5, 7), and proximal LCX (AHA-10). The reproducibility for the demonstration of distal segments of LAD, LCX, and RCA (AHA-9, 14, 21) was 94.19%, 72.09%, and 96.51%, respectively. Conclusion This is a simple and practical localization strategy for MRCA. It could image the proximal and middle segments of the coronary arteries with good reproducibility, which indicates the potential for clinical application.

Objective To observe the therapeutic effect of tumor necrosis factor ?(TNF ?) on C6 glioma using 1?H MR spectroscopy, and to evaluate the practical value of 1?H MR spectroscopy in observing therapeutic effect Methods C6 cell mixed with low boiling point argarous were inoculated in caudate nuclear in 33 rats by using sterotatic method By using high magnetic field spectrometer, high resolution 1?H MR spectroscopy was carried at a 3 day interval until 15 days after treatment with TNF ? The relative choline containing compound (Cho),N acetyl aspartate (NAA),creatine (Cr), Cho/Cr,NAA /Cr,and NAA/Cho were analyzed with statistic method Results The Cho decreased obviously 3 days after TNF ? treatment( P

Objective To evaluate the effect of quick injection combining with slow infusion of Gd-DTPA on T1 relaxation of the blood. Methods Fifteen volunteers were recruited for coronary MRA study using a navigator-gated 3D-FIESTA sequence. Coronary MRA were acquired on the same segments two times at 5 minutes and 15 minutes after Gd-DTPA administration. Contrast agent was injected biphasically with 10 ml at a flow rate of 1.5 ml/s and 20 ml at 0. 05 ml/s to prolong the T1 relaxation effect. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated pre- and post-contrast MRA. Image quality was compared using t-test. Results The SNR and CNR at 5 minutes after contrast injection (35.37 ±6. 84 and 21.57 ± 6. 08 ) were significantly higher than that of pre-contrast MRA ( 27.38 ± 6. 24 and 13.19 ±6. 50). The SNR at 15 minutes after contrast injection (33. 81 ±9. 43) was higher than that of precontrast MRA, but there was no statistically difference(t = 1. 885 ,P =0. 074). The CNR at 15 minutes after contrast injection (21.20 ± 7.65) was significantly higher than that of pre-contrast MRA. The SNR and CNR at 15 minutes after contrast injection were no significant different compared with those at 5 minutes after contrast injection. Conclusion T1-shorting effect in the blood can be prolonged by quick injection combining with slow infusion of Gd-DTPA ,which meet with the need of multiple scans of coronary MRA.

Objective To get a MR imaging protocol for coronary arterial wall in vitro. Methods MR examinations were performed in 10 fresh porcine hearts. Three dimensional fast imaging employing steady state acquisition (3D FIESTA) was used to delineate left anterior descending artery (LAD), while 2D spin-echo T1W was performed with 8-channel head surface coil, temporomandibular surface coil and knee coil with the same parameters. T1WI was obtained with 384×256 and 512×512 in matrix using temporomandibular surface coil, and then T1WI, PDW and T2WI with fat saturation were obtained with different NEX using temporomandibular surface coil after injecting Resovist in LAD. Signal of the LAD wall, lumen, fat tissue adjacent to LAD, myocardium of anterior part of interventricular septum and noise were respectively measured. Signal-to-noise ratio (SNR) of image, contrast to noise ratio (CNR) between the wall and lumen (CNR1), CNR between the wall and surrounding fatty tissue (CNR2) were calculated. Results The SNR and CNR1, CNR2 of SE T1WI with temporomandibular coil were higher than those with 8-channel head surface coil and knee coil. SNR and CNR1, CNR2 of SE T1WI with 384×256 matrix were higher than those with 512×512 matrix. SNR and CNR1, CNR2 using 3 NEX were the highest. Conclusion Good SNR and CNR of porcine coronary wall can be achieved using temporomandibular surface coil, 384×256 in matrix and NEX of 3.

Objective: To assess the reproducibility of high resolution MR imaging(MRI) in measuring the vascular wall area in atherosclerotic carotid artery. Methods: Twenty four subjects (male 18, female 6, aged 60 78 years) with 50% 79% stenosis (confirmed by Doppler ultrasound) were recruited for the study. Two independent MRI examination were conducted within 2 weeks using high resolution imaging on a 1.5 T scanner (Signa, GE Medical Systems). Three slices were selected (4 mm distal to the bifurcation, just under the bifurcation and 4 mm proximal to the bifurcation) from the bilateral carotid artery to measure the luminal, outer wall boundary and wall area. The above process was done by 2 observers blinded to each other's results. The Interscan and Interobserver variations were assessed by paired Student's t test. Results: There was no significant difference in lumen, outer wall boundary and wall area measurement for both Interscan and Interobserver comparison. Conclusion: High resolution MRI of the human carotid artery in measuring the vessel lumen and wall areas has high reproducibility. MRI can also be used to monitor the progression of atherosclerotic plaque of carotid artery.