Latest Issue
Volume 0 ， Issue 4 ， 2006
- Abstract：With the development of magnetic resonance （MR） technology, the concern is focused on molecular and physiological imaging besides structural information. Ultra high field MR scanner shows great superiority. 3.0-T MR scanners provide almost two-fold signal-to-noise ratio （SNR） compared with a standard 1.5-T MR scanner. The higher baseline SNR can be converted into a variety of alternative benefits. There are still some other changes brought about by 3.0-T, such as higher sensitivity to motion, susceptibility effect, more difference in resonant frequency among different metabolites, and so on. These features may be a double-edged sword in structural and functional imaging. But with the ceaseless progress of the technology and gains in experience, 3.0-T systems will provide more information and show more advantages.Keywords：ultra high field magnetic resonance;signal-to-noise ratio;morphological imaging;functional magnetic resonance imaging4|14|2Updated：2024-04-10
- Abstract：Objective To evaluate metabolic abnormalities in patients with mesial temporal lobe epilepsy （MTLE） with proton magnetic resonance spectroscopy （MRS） using a 3.0T MR scanner. Methods Sixty-three patients （32 women and 31 men） with diagnosed MTLE underwent diagnostic MR imaging （MRI） and proton MRS using a 3.0T MR scanner. The clinical history and interictal epileptiform discharges （IEDs） were recorded. Sixteen healthy volunteers served as control. The results of proton MRS were compared with the findings of electroencephalogram and structural MRI findings. Results Twenty-seven of the 63 patients with MTLE showed unilateral hippocampal sclerosis, and 9 showed bilateral hippocampal sclerosis. The concentration ratio of N-acytelaspartate （NAA）/ in the hippocampal region of MTLE patients （0.64±0.07） was significantly lower than control （0.80±0.05, P= 0.023）. In the patients with unilateral hippocampal sclerosis, NAA/（Cr+Cho） in the hippocampal region ipsilateral to the sclerotic hippocampus （0.56±0.06） was significantly lower than the ratio in the contralateral hippocampal region （0.69±0.07, P<0.001）. There was significant difference in hippocampal NAA/（Cr+Cho） between the refractory patients and the non-refractory patients （0.64±0.05 vs. 0.71±0.07, P=0.04）. Forty-five patients were lateralized by IEDs, while 49 patients were lateralized by metabolite ratio. And lateralization determined by proton MRS and IEDs was concordant in 33 patients. Conclusions MRS as a noninvasive tool adds helpful metabolite information to routine MRI in evaluation of MTLE. The method is well established and should be a routine clinical application in the investigation of epilepsy.Keywords：magnetic resonance spectroscopy;temporal lobe epilepsy;electroencephalogram4|30|4Updated：2024-04-10
- Abstract：Objective To investigate the effects of long-term low dose hormone replacement therapy （HRT） on postmenopausal women in hormone level, cognition score, hippocampus volume, and magnetic resonance spectroscopy （MRS） parameters. Methods A total of 182 postmenopausal women aged 50-87 years were chosen at Peking Union Medical College Hospital and assigned to HRT group and control group. The volunteers of HRT group had taken low dose hormone [estradiol （E 2 ） 0.5-1.0 mg and progesterone 0.5-2.0 mg, once a day] for 4-33 years. The concentrations of E 2 , progesterone, and testosterone were measured using enzyme-linked immunosorbent assay （ELISA）. The gene types of apolipoprotein E （ApoE） were measured by polymerase chain reaction, and the subjects with susceptible genes （ApoE ε3/ε4） of Alzheimer’s disease （AD） were screened. Their hippocampus volumes and MRS parameters were obtained through magnetic resonance imaging （MRI）, and results in two groups were analyzed by statistical method. Results Compared with control group, the concentrations of E 2 at each age stage in HRT group were significantly higher （P<0.05） except the 80-89 years old subgroup; yet, there were no statistical differences in the concentrations of progesterone and testosterone between the two groups. There was no obvious difference in ApoE subtypes distribution between the two groups. The results of hippocampus MRI for the subjects with susceptible genes ApoE ε3/ε4 （HRT group 14 cases, control group 11 cases） showed that the ratio of bilateral hippocampus volume to whole brain volume in HRT group （0.406±0.028） was significantly higher than control group （0.369±0.031, P<0.05）. The results of 1 H MRS for the subjects with susceptible genes ApoE ε3/ε4 （HRT group 12 cases, control group 11 cases） showed that the N-acetylaspartate/total creatine at the area of hippocampus in HRT group （1.54±0.08） were significantly higher than control group （1.45±0.13, P<0.05）. Conclusions For postmenopausal women, long-term low dose HRT can maintain the physiological concentration of E 2 in plasma. Furthermore, the hippocampus MRI performed on those with ApoE ε3/ε4 genes shows that long-term low dose HRT can prevent hippocampus atrophy, which is beneficial to maintain the brain function and prevent AD.Keywords：long-term low dose hormone replacement therapy;estrogen;apolipoprotein E;hippocampus;magnetic resonance spectroscopy4|41|5Updated：2024-04-10
- Abstract：Objective To investigate the difference in interictal perfusion patterns between refractory and non-refractory temporal lobe epilepsies evaluated with flow-sensitive alternating inversion recovery （FAIR） magnetic resonance （MR） sequence. Methods Nine patients with refractory temporal lobe epilepsy, 21 patients with non-refractory temporal lobe epilepsy, and 13 normal volunteers underwent FAIR MR scanning. The relative cerebral blood flow （rCBF） in bilateral hemispheres and mesial temporal lobes were measured. And we also calculated the asymmetry index （AI） values. Results The AI values of bilateral hemispheres in refractory and non-refractory epilepsy patients were both significantly different from those of volunteers （P=0.012 and 0.029, respectively）. There was significant difference in AI values of bilateral mesial temporal lobes between non-refractory epilepsy patients and volunteers （P=0.049）, while no significant difference between refractory epilepsy patients and volunteers. Conclusions The hypoperfusion pattern of interictal refractory temporal lobe epilepsy patients is different from that of non-refractory patients. Although the hypoperfusion tends to extend out of temporal lobes in all patients, the refractory epilepsy patients have a preference of bilateral mesial temporal hypoperfusion, which may be valuable for evaluating prognosis.Keywords：flow-sensitive alternating inversion recovery;temporal lobe epilepsy;cerebral blood flow4|21|0Updated：2024-04-10
- Abstract：Objective To describe the characteristic magnetic resonance imaging （MRI） appearance of cerebral schistosomiasis. Methods Twenty-five patients whose diagnosis of central nervous system （CNS） schistosomiasis had been pathologically （n=8） and clinically （n=17） confirmed were randomly selected. MRI was performed on a Signal 1.5T MRI scanner before and after the intravenous administration of gadopentetate dimeglumine constrast medium. We reviewed the MRI studies obtained at the time of initial presentation, as well as follow-up studies obtained during and after medical treatment. Results Immunological tests in 15 patients indicated schistosomiasis haematobium. Contrast-enhanced T1-weighted images in 22 cases showed central linear enhancement surrounded by multiple enhancing punctate nodules, which appeared “arborized”. Through operation and pathological examination, 8 cases had the granuloma formation of schistosomal eggs extensive surrounded by inflammation and venous congestion. And 17 cases were treated with praziquantel and corticosteroid therapy. And they were followed up for 2 months by taking MRI, which turned out to be complete resolution of the enhancing structure and edema. At follow-up, all the patients’ initial symptoms also resolved. Conclusion The specified MRI enhancement pattern of cerebral schistosomiasis is common in most cases of CNS schistosomiasis, so it should be taken account into the diagnosis of cerebral schistosomiasis.Keywords：cerebral schistosomiasis;diagnosis;magnetic resonance imaging4|20|7Updated：2024-04-10
- Abstract：Objective To study the activation changes of the brain in patients with amyotrophic lateral sclerosis （ALS） while executing sequential finger tapping movement using the method of blood oxygenation level dependent （BOLD） functional magnetic resonance imaging （fMRI）. Methods Fifteen patients with definite or probable ALS and fifteen age and gender matched normal controls were enrolled. MRI was performed on a 3.0 Tesla scanner with standard headcoil. The functional images were acquired using a gradient echo single shot echo planar imaging （EPI） sequence. All patients and normal subjects executed sequential finger tapping movement at the frequency of 1-2 Hz during a block-design motor task. Structural MRI was acquired using a three-dimensional fast spoiled gradient echo （3D-FSPGR） sequence. The fMRI data were analyzed by statistical parametric mapping（SPM）. Results Bilateral primary sensorimotor cortex （PSM）, bilateral premotor area （PA）, bilateral supplementary motor area （SMA）, bilateral parietal region （PAR）, contralateral inferior lateral premotor area （ILPA）, and ipsilateral cerebellum showed activation in both ALS patients and normal controls when executing the same motor task. The activation areas in bilateral PSM, bilateral PA, bilateral SMA, and ipsilateral cerebellum were significantly larger in ALS patients than those in normal controls （P<0.05）. Extra activation areas including ipsilateral ILPA, bilateral posterior limb of internal capsule, and contralateral cerebellum were only detected in ALS patients. Conclusions Similar activation areas are activated in ALS patients and normal subjects while executing the same motor task. The increased activation areas in ALS patients may represent neural reorganization, while the extra activation areas in ALS patients may indicate functional compensation.Keywords：amyotrophic lateral sclerosis;blood oxygenation level dependent;functional compensation;neural reorganization4|29|10Updated：2024-04-10
- Abstract：Objective To study the characteristics of spectra on proton magnetic resonance spectroscopy （ 1 H-MRS） and its value in patients with mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes （MELAS）. Methods Seven clinically diagnosed patients with MELAS underwent magnetic resonance imaging （MRI） and 1 H-MRS examinations. The 1 H-MRS techniques, characteristics of the spectra, and its correlation with the laboratory tests were analyzed. Results Cerebral abnormalities were revealed in all 7 patients on conventional MR images, and most abnormal signals were observed in bilateral occipital, parietal, and temporal lobes. We found 4 cases with basal ganglia involvement, 2 cases with mild frontal lobe lesions, and 1 case with involvement of lateral cerebral peduncles and thalami. Additionally, 1 patient was involved with left insular lobe. Spectra from prominent lesions in brain parenchyma showed lactate doublet peak in 6 patients, 3 of whom were also noted lactate peak in ventricular cerebrospinal fluid （CSF）. Conclusion 1 H-MRS may provide more direct information about the metabolism changes, which aids to affirm the diagnosis, and may replace the conventional invasive method of quantifying lactate in CSF.Keywords：mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes;magnetic resonance spectroscopy;lactate4|37|11Updated：2024-04-10
- Abstract：Objective To compare contrast-enhanced magnetic resonance imaging （ceMRI） with nuclear metabolic imaging for the assessment of myocardial viability in patients with chronic ischemic heart disease. Methods Twenty patients with suspected chronic ischemic heart disease underwent ceMRI and technetium-99m sestamibi single-photon emission computed tomography （SPECT）. Patients with positive SPECT results also underwent 18 F-fluorodeoxyglucose （FDG） SPECT. In a 17-segment model, the segmental extent of hyperenhancement （SEH） by ceMRI was compared with segmental FDG and sestamibi uptake by SPECT. Correlation between the extent of hyperenhancement by ceMRI and left ventricular function was analyzed. Results Seven patients got negative results both in ceMRI and technetium-99m sestamibi SPECT. The rest 13 patients with positive results then underwent 18 F-FDG SPECT. In 221 segments of 13 patients, SEH was （2.1±8.2）%, （25.0±13.7）%, and （57.7±23.6）% in segments with normal metabolism/perfusion, metabolism/perfusion mismatch, and matched defects, respectively, and there were significant differences between either two of them （all P<0.05）. By receiver operating characteristic curve analysis, the area under the curve was 0.95 for the differentiation between viable and non-viable segments. At the cutoff value of 34%, SEH optimally differentiated viable from non-viable segments defined by SPECT. Using this threshold, the sensitivity and specificity of ceMRI to detect non-viable myocardium as defined by SPECT were 92% and 93%, respectively. Hyperenhancement size by ceMRI was correlated negatively with the left ventricular ejection fraction （r=-0.90, P<0.01） and positively with left ventricular volumes （r=0.62 for end-diastolic volume, r=0.75 for end-systolic volume, both P<0.05）. Conclusion CeMRI allows assessment of myocardial viability with a high accuracy in patients with chronic ischemic heart disease.Keywords：magnetic resonance imaging;single-photon emission computed tomography;myocardial viability4|15|0Updated：2024-04-10
- Abstract：Objective To explore the imaging and related clinical characteristics of magnetic resonance （MR） delayed enhancement in patients with ischemic or nonischemic heart disease. Methods Thirty-two cases who underwent MR myocardial cine and delayed enhancement imaging from January 2004 to October 2006 were retrospectively analyzed. The cine sequence imaging included the four-chamber view and the left ventricular short axis view. The delayed enhancement imaging was taken 10 minutes after the infusion of gadolinium from the antecubital vein with a segmented inversion-recovery-prepared T1-weighted fast gradient echo sequence. Patients underwent coronary computed tomography angiography （CTA） two weeks before or after the MR imaging examination. Combined with clinical history, the clinical and MR imaging characteristics of the patients who had delayed enhancement were analyzed. Results MR delayed enhancement could be found in 16 cases. Among them, 12 cases had ischemic heart disease. Their coronary CTA showed one to three vessel diseases. The delayed enhancement was transmural or subendocardium, and the area of delayed enhancement corresponded well with one or more coronary arteries which had severe stenosis or occlusion. Four cases had nonischemic heart diseases. One case was dilated cardiomyopathy, with diffuse small midwall spots in delayed enhancemen and only 30% stenosis of the anterior descending coronary artery in coronary CTA. One case was hypertrophic cardiomyopathy, with delayed enhancement of strip- and patch-shaped at midwall of the hypertrophic myocardium. One case was restrictive cardiomyopathy, and the delayed enhancement was located in the area of subendocardium of both the right and left ventricles. Coronary CTA of these two cases were normal. The other case was a mass of the lateral wall of the left ventricle, and the delayed enhancement with a clumpy shape was located in the lateral wall of the left ventricle. Conclusions MR myocardial delayed enhancement is not a specific sign of myocardial infarction of ischemic heart disease. Nonischemic heart diseases including all kinds of primary cardiomyopathy and some other diseases affecting myocardium can also cause delayed enhancement, but their characteristics are different. The differentiation of the etiology of the nonischemic heart disease with delayed enhancement relies upon the intimate connection with clinical history and the cine sequence MR images.Keywords：cardiac imaging;magnetic resonance imaging;contrast enhancement4|17|0Updated：2024-04-10
- Abstract：Objective To investigate the role of perfusion-weighted magnetic resonance imaging （MRI） in evaluation of cirrhotic liver. Methods With a 4F catheter, 1% diluted carbon tetrachloride （1 ml/kg） was selectively injected into right or left hepatic artery of 12 dogs fortnightly. The half liver into which carbon tetrachloride was injected was called as study side （SS）, while the other half liver without carbon tetrachloride injection was called as study control side （SCS）. Conventional and perfusion-weighted MRI were performed in every 4 weeks. Via a 4F catheter, 5ml gadolinium diethylentriamine pentaaceti acid （Gd-DTPA） dilution was injected into superior mesenteric artery at the 5th scan. The signal intensity-time curves of SS, SCS, and portal vein were completed in MR workstation. The maximal relative signal increase （MRSI）, peak time （t p ）, and slope of the curves were measured. Results On conventional MR images, no abnormalities of externality and signal intensity were observed in both SS and SCS of liver at each stage. The mean t p , MRSI, and slope of intensity-time curves in normal liver were 10.56 seconds, 1.01, and 10.23 arbitrary unit （au）/s, respectively. Three parameters of curves didn’t show obvious change in SCS of liver at every stage. Abnormal perfusion curves occurred in SS of liver at the 12th week after the 1st injection. The abnormality of perfusion curve in SS was more and more serious as the times of injection increased. The mean t p , MRSI, and slope intensity-time curves in SS of liver were 19.45 seconds, 0.43, and 3.60 au/s respectively at the 24th week. Conclusion Perfusion-weighted imaging can potentially provide information about portal perfusion of hepatic parenchyma, and to some degree, reflect the severity of cirrhosis.Keywords：liver cirrhosis;animal model;magnetic resonance imaging;perfusion imaging4|35|12Updated：2024-04-10
- Abstract：Objective To investigate the value of in vivo proton magnetic resonance spectroscopy （MRS） in the assessment of hepatocellular carcinoma （HCC） and monitor its metabolic change shortly after transcatheter arterial chemoembolization （TACE）. Methods In this prospective study, 28 consecutive patients with large HCC （≥3 cm in diameter） confirmed by fine needle aspiration biopsy were recruited. The 1 H MRS of all hepatic lesions and some uninvolved liver parenchyma were performed with 1.5T whole body MR scanner. Among them, 15 cases were evaluated again about one week after TACE. The main metabolites such as choline and lipid before and after interventional therapy were measured to assess the early response of the tumor. Results The technical success rate of 1 H MRS in liver was high （33/41, 80%）, closely related to breath motion, location of lesion, and size of voxel. In spectra, the choline compound peak of HCC elevated compared with uninvolved liver parenchyma. After TACE, both the amplitude and the area of choline resonance peak significantly descended （choline-to-lipid ratios from 0.352±0.080 to 0.167±0.030, P=0.026; from 0.205±0.060 to 0.070±0.020, P=0.042, respectively）; yet lipid resonance peak ascended. Conclusions In vivo 1 H MRS is technically feasible for the evaluation of large focal hepatic lesions, however, the reproducibility and stability are not as good as routine MR scan. 1 H MRS can monitor the early stage metabolic changes of HCC after TACE but limitation like quantification still exists.Keywords：hepatocellular carcinoma;magnetic resonance imaging;proton magnetic resonance spectroscopy;transcatheter arterial chemoembolization4|32|36Updated：2024-04-10
- Abstract：Objective To evaluate the role of 1 H spetral selected point-resolved spectroscopy （SS-PRESS） sequence in distinguishing benign from malignant breast lesions by the malignancy marker of choline peak and to investigate the factors influencing the diagnosis. Methods A total of 131 patients （aged 24-83 years, average 44.8 years） were enrolled in this study. The examinations were performed on a 1.5T scanner with four-channel phased array breast coil. Single-voxel proton magnetic resonance spectroscopy （ 1 H MRS） was acquired by SS-PRESS sequence in these patients referred to surgical or biopsy consultation. Results Among these patients, 74 were proved to have breast carcinomas and 57 have benign lesions by histopathological examinations. Thirty-one elevated choline peaks were observed in these 74 confirmed malignant lesions, and 5 detectable choline peaks were demonstrated in the 57 benign lesions. The sensitivity and specificity of 1 H SS-PRESS MRS were 41.9% and91.2%, respectively. The main factors influencing the diagnosis were signal-to-noise ratio and pathological type. Conclusions 1 H SS-PRESS MRS can provide a noninvasive, biochemical measurement of metabolism and improve the specificity of breast magnetic resonance imaging. Choline peak in vivo is a specific but not sensitive marker of malignancy. Technique factors and histopathological characterization of lesions influence the detection rate.Keywords：magnetic resonance spectroscopy;spetral selected point-resolved spectroscopy;breast lesion;choline;pathology4|21|0Updated：2024-04-10
- Abstract：Objective To determine the magnetic resonance （MR） imaging findings of an ovarian mass which are most predictive of malignancy and assess the value of intravenous gadolinium administration in the characterization of an ovarian mass. Methods Totally 74 consecutive patients with a clinically or sonographically indeterminate adnexal mass underwent MR imaging, of whom 59 had subsequent surgical resection of 70 adnexal masses. These 59 patients formed the study population. MR imaging studies were prospectively and independently reviewed by a senior and a junior radiologist. The senior radiologist also reevaluated the studies in a blind fashion after a minimum 6 months interval. The sensitivity, specificity, positive predictive value, and negative predictive value of contrast-enhanced and unenhanced MR imaging were evaluated. Results The most predictive MR imaging findings for malignancy were presence of vegetations in a cystic lesion and presence of necrosis in a solid lesion. The odds ratio was even higher when the ancillary finding of peritoneal metastasis or ascites was present. Contrast media contributed significantly to lesion characterization. Total 70 ovarian masses were detected by contrast-enhanced MR imaging including 37 malignant ovarian masses and 33 benign ovarian masses with 87% （61/70） accuracy, 86% （32/37） sensitivity, 88% （29/33） specificity, 89% （32/36） positive predictive value, and 85% （29/34） negative predictive value, whereas 70 ovarian masses were detected by unenhanced MR imaging with 74% （52/70） accuracy, 73% （27/37） sensitivity, 76% （25/33） specificity, 77% （27/35） positive predictive value, and 71% （25/35） negative predictive value. There were significant differences in accuracy （P<0.01）, sensitivity （P<0.01）, specificity （P<0.01） between contrast-enhanced and unenhanced MR imaging. Conclusion Contrast-enhanced MR imaging is highly accurate in detection and characterization of complex adnexal masses.Keywords：ovarian tumor;malignancy;magnetic resonance imaging4|26|6Updated：2024-04-10
- Abstract：Objective To distinguish the edema, injury, or rupture in the traumatic skeletal muscle fiber in vivo using diffusion tensor imaging （DTI） and tractography on magnetic resonance imaging （MRI）. Methods The skeletal muscle trauma models were made in 4 rabbits （eight hindlimbs） by iron discus （weight 1.0 kg, diameter 6 cm） falling down vertically from 45 cm height to rabbits’ thighs. Conventional sequences and two-dimensional （2D） diffusion-weighted （DW） spin-echo （SE） echo planar imaging （EPI） sequence with fat suppression （b=600 s/mm2） were performed on 1.5T MRI scanner. The grading of edema, injury, and fiber rupture in the damaged muscle were made according to their histopathological views, which was consistent with the images. The mean apparent diffusion coefficient （ADC） values and fractional anisotropy （FA） values were measured from the region of interests （ROIs） of all groups on 2D DW images used for tractography. Analysis of variance test was performed to analyze all data. Results ADC values of the areas in normal muscle, edema muscle, injury muscle, and ruptured muscle were （6.12±1.34）×10 -3 , （6.38±1.30）×10 -3 , （8.06±0.97）×10 -3 , and （9.57±0.93）×10 -3 mm 2 /s, respectively. There was significant difference among groups （P<0.001）, but no difference between edema muscle and normal muscle group （P>0.05）. The FA values of normal muscle, edema muscle, injury muscle, and ruptured muscle were 0.42±0.12, 0.36±0.12, 0.26±0.09, 0.12±0.08, respectively, with a significant difference among groups （P<0.001）. In the edema muscle, the tracking cross-fiber could be seen but it decreased slightly. In the injury muscle, the tracking fiber decreased markedly. In the ruptured muscle, the transverse-orientation tracking fiber vanished, yet some interrupted longitudinal-orientation tracking fiber could be found. Conclusion The edema, injury, and rupture of muscle fiber in rabbit damaged skeletal muscle can be verified according to the ADC and the FA on DTI and tractography.Keywords：traumatic skeletal muscle;grade;diffusion tensor imaging;tractography4|28|19Updated：2024-04-10
- Abstract：Elasticity is an important physical property of human tissues. There is a tremendous difference in elasticity between normal and pathological tissues. Noninvasive evaluation of the elasticity of human tissues would be valuable for clinical practice. Magnetic resonance elastography（MRE）is a recently developed noninvasive imaging technique that can directly visualize and quantitatively measure tissue elasticity. This article reviewed the MRE technique and its current status.Keywords：magnetic resonance imaging;elasticity;tissue characterization4|26|8Updated：2024-04-10
-
- © 2024 Chinese Academy of Medical Sciences 京ICP备09064830号-19
京公网安备11010802024621 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
0