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Objective To investigate the effect of manganese-enhanced MRI (MEMRI) at 7.0T for tracing nerve tracts in rat brain in vivo. Methods With brain stereotactic apparatus, 0.4 μl Mncl_2 with aqueous solution of 1 mol/L was injected into the right somatosensory cortex of 9 SD rats. MR scan was performed for tracing corticospinal tracts and other coherent nerve tracts pre-, and 24, 48, 72 h, 7 days post-injection with 7.0T micro-MRI system, respectively. Results Corticospinal tracts were showed in intact after Mn~(2+) administration from somatosensory cortex, thalamus, cerebral peduncle to pons at the time point of 24, 48, 72 h and 7 days, while the best tdisplaying was achieved at 24-48 h after Mn~(2+) administration. Simultaneously a small quantity of Mn~(2+) reached the opposite somatosensory cortex through the corpus callosum. Conclusion MEMRI for tracing rat nerve tracts can be showed clearly with 7.0T MRI. The location of manganese-enhanced corticospinal tracts in agreement with the rat brain atlas in stereotaxic is in agreement with that Paxinos' published. MEMRI can display the relationship between the two sides of hemisphere, and may play an important role in investigating the brain function and nerve plasticity after nerve injury in vivo.
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Objective To investigate the application of CT microvascular permeability surface (PS) in acute ischemic stroke. Methods Thirty patients suffering from acute or sub-acute cerebral infarction underwent CT perfusion (CTP) combining with CTA. Cerebral hemodynamic parameters (cerebral blood flow [CBF], cerebral blood volume [CBV], time to peak [TTP], PS) between lesions and contralateral side were compared. The manifestation of microvascular hyper permeability were analyzed. Results Significant differences were found in cerebral hemodynamic parameters between the core of cerebral infarction and the contralateral hemisphere (P＜0.05). There was no significant difference in CBF and CBV between the surrounding of cerebral infarction and the contralateral hemisphere, but PS and TTP showed delaying and heightening, the difference was significant (P＜0.05). High-density extravasation of contrast media in infarction zone was observed 30 min after CTP in 3 patients, the value of PS reached (9.20±1.43) ml/100 (ml·min). Conclusion CT microvascular PS may monitor hemorrhagic transformation in acute ischemic stroke, and guide thrombolytic therapy.
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Objective To study the role of manganese-enhanced MRI(MEMRI) in the depiction of cortical architecture of rat brain after systemic administration of Mn~(2+) through caudal vein and compare the effects of normal or opened blood-brain barrier on the manganese-enhanced MRI. Methods Fifteen SD rats were randomly divided into three groups according to ranked list of random. Blood-brain barrier was opened in short time by the injection of 30% mannitol via the right internal carotid artery, in group A, then 100 mmol/L MnCl_2 physiologic saline solution was delivered through vena caudalis, and MRI was performed 12 hours later. In group B, 100 mmol/L MnCl_2 physiologic saline solutions was administrated through vena caudalis, following normal saline injection into the right internal carotid artery, and MRI was performed 12 hours later. The group C served as normal control group. All images were acquired with a 7.0 T microMR scanner. Signal-to-noise ratios (SNR) in regions of interest were measured by Paravision 4.0 and the differences of three groups were compared by using one-way ANOVA. The differences of SNR on both sides of hemispheres were compared by using paired t test. Results MEMRI could show the gray matter and white matter of rat brain and the anatomy borders between somatosensory cortex and motor cortex clearly. Periventricular structures such as hippocampus, dentate gyms, habenula united, and olfactory bulb could also be showed clearly. Symmetrical enhancement on both sides of the cortex and banded structures was shown clearly in group B. The SNR increased and the differences were significant in right cerebral cortex, both sides of cerebellar cortex, hippocampus and pituitary, among three groups (right cerebral cortex 35.2±7.0,30.1±2.4,26.6±2.8,F =4.36,P=0.038;left cerebellar cortex 27.1±5.2,29.4±3.8,19.4±4.5, F=6.66, P=0.011;right cerebellar cortex 27.8±3.8,28.5±4.2,20.4±4.8, F=5.84, P=0.017; left hippocampus 34.5±4.9,38.1±5.3,24.5±3.6, F=11.38, P=0.002; right hippocampus 35.3±5.5, 37.6±4.7,25.6±3.0,F=9.93,P=0.003;pituitary 39.5±3.8,52.6±9.1,26.2±4.2,F=22.80, P=0.001) after systemic administration of Mn~(2+). Asymmetric enhancement on two sides of cortex was shown in group A. The mannitol-infused side was enhanced obviously but displayed blurring banded structures. However,the SNR differences of both sides of hemispheres in group A and B were not significant (P >0.05). Conclusions After systemic administration of MnCl_2 through vena caudalis, MEMRI could map the laminar architectures and the anatomy border of functional zone of somatosensory cortex specifically. High concentration of mannitol could open blood brain barrier(BBB) effectively and have distinct impacts on the architectures displayed in MEMRI. Opening or maintaining BBB in MEMRI had respective characteristics, and it should be selected according to practical needs.
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Objective To assess the value of whole cerebral perfusion weighted map (PWM) and whole cerebral perfusion blood volume (PBV) integrating in scan protocol about CT perfusion (CTP) combined with CT angiography (CTA) in acute cerebral infarction. Methods Twenty-three patients with acute cerebral infarction proved clinically underwent CTP examination combined with CTA. The color-coded images of PWM and PBV were attained using workstation, and the raw data of contract CTA images and subtractive images between contract CTA and non-contract CTA were processed. The diagnostic sensitivity and the value of CTP and PWM, PBV integrating CTP in acute cerebral infraction were evaluated. Results Seven of 9 patients with negative results on CTP images had positive expressions on PWM and PBV images. The sensitivity of CTP was 60.87% and the sensitivity of PWM and PBV integrating CTP was 91.30%. Conclusion The scan protocol of PWM, PBV integrating CTP not only increases detection rate of acute cerebral infraction, but also has ability to predict the clinical prognosis of patients with cerebral infraction.
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Objective To investigate the anatomic appearance in the region of the torcular Herophili by using MR and to evaluate its clinical significance Methods This study involved 123 healthy subjects All subjects underwent initial T 1W and T 2W MR examination in order to exclude intracranial occupying disease and vascular malformation Then, images of venous sinuses were obtained in the region of the torcular Herophili 72 of these subjects were examined with coronal 2D TOF MR venography (MRV), 44 cases were examined with coronal 3D PC angiography, and other 7 volunteers were examined with both of the two aforementioned methods Results (1) The venous drainage dominance showed mainly to the right side in 84 cases, mainly to the left side in 23 cases, equal drainage in 16 cases (2) According to the relation among the sinuses in the region of the torcular Herophili, all subjects in this study could be grouped into 4 types: Type 1, including those subjects in which a confluence of sinuses existed or the superior sagittal sinus and the straight sinus forked, and the forking of both sinuses joined to form the lateral sinuses Type 2, including those subjects in which the sagittal sinus drained into one side and the straight sinus drained into the other Type 3, including those subjects in which the superior sagittal sinus and the straight sinus joined and mainly drained into the right side Type 4, including those subjects in which the superior sagittal sinus and the straight sinus joined and mainly drained into the left side Conclusions MR angiography provides a useful method to show the anatomic features in the region of the torcular Herophili The pattern of the classification is considered important to assess the venous drainage dominance and helpful to deduce existent and/or potential collateral pathway These findings may be useful for diagnostic and operative procedure
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Objective (1) To determine the relationship between the MR signal intensity and the actual flow velocity under steady flow condition (2) to analyze the influence produced by the angle (?) between the flow direction and the velocity encoded gradient direction, and flip angle as well as section thickness on the velocity measurement under oblique flow condition (3) to develop a suitable protocol for using this method to measure volumetric flow rate in the transverse sinus system Methods Flow phantom, which simulated blood flow conditions in the transverse sinus system, consisted of a fluid filled cylinder and a bent tube with a 3 4 mm internal diameter A 1 5 T superconductive MR imager and VIGRE sequence were used for these studies A suitable protocol was based on consideration of the effects of (1) the accuracy of velocity and transverse area measurement of flow, and (2) signal to noise ratio (SNR) Results (1) Signal intensity (y) determined by MR and the actual flow velocity (x) showed straight line correlation, y=68 914x+357 206, R 2=0 998 (2) As the angle (?) increased, the transverse area of the signal determined by MR also increased, but the value of flow velocity decreased (3) As the flip angle increased, the SNR varied from 5 7 to 11 2 The maximum SNR was obtained with 30?flip angle (4) As the section thickness increased, the SNR and the transverse area of the signal determined by MR slightly increased Conclusions Phase contrast MR imaging is a practical method for measuring volumetric flow rates The angle (?) influenced the accuracy of flow velocity and the measurement of transverse area of flow whereas the flip angle and the section thickness substantially influenced the signal to noise ratio and the transverse area of flow
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Objective To assess the accuracy of two-dimensional phase contrast (2D-PC) MR method for blood flow measurement within transverse sinusesby comparing this method with cine phase contrast (cine-PC) MR and Doppler in volunteers and patients. Methods (1) A total of 12 transverse sinuses were examined in 8 healthy volunteers. 2D-PC MR and cine-PC MR were used respectively to measure the transverse area of flow, the flow velocities, and the volumetric flow rates in the same position in every transverse sinus. Paired t-test was used for comparison between the results determined by 2D-PC MR and that determined by cine-PC MR. (2) A total of 6 transverse sinuses were examined in 5 patients who needed operation. 2D-PC MR was used to determine the blood flow velocity of transverse sinus before operation, and Doppler was used to determine the blood flow velocity of the same transverse sinus during operation. The linear regression analysis was used for statistical analysis. Results (1) Statistical analysis indicated that there were no significant difference among the transverse area of flow (t=-1.106, P=0.293), the flow velocities (t=0.262, P=0.798), and the volumetric flow rates (t=0.439, P=0.669) measured by using 2D-PC MR and cine PC MR, respectively. (2) The correlation between flow velocities determined by 2D-PC MR imaging before operation and that determined by Doppler during operation was in excellent agreement (=1.303x+0.62,r 2=0.88). Conclusion 2D-PC MR may be a practical convenient method for blood flow measurement within transverse sinuses system.