Analysis of Safe Storage Moisture Content of Mume Flos Decoction Pieces Based on Theory of Water Activity and Water Molecular Mobility / 中国实验方剂学杂志

ObjectiveThe hygroscopic properties of Mume Flos decoction pieces were studied from the perspectives of macroscopic［water activity（Aw）］ and microscopic（water molecular mobility）， which provided a theoretical basis for the determination of the safe storage moisture content. MethodAdsorption isotherm of Mume Flos decoction pieces was obtained by static weighing method， and seven common hygroscopic models were fitted and estimated. The best model was selected according to the principle that determination coefficient（R2） was closer to 1， residual sum of squares（RSS） was closer to 0 and Akaike information criterion（AIC） was smaller. According to the optimal model， the absolute and relative safe moisture contents of Mume Flos decoction pieces at 25， 35， 45 ℃ was calculated. Low-field nuclear magnetic resonance（LF-NMR） was used to measure the water molecular mobility in the hygroscopic process of Mume Flos decoction pieces. ResultThe best model to describe the adsorption isotherm of Mume Flos decoction pieces was the Peleg model. According to the model expression， the absolute safe moisture contents of Mume Flos decoction pieces at 25， 35， 45 ℃ were 9.59%， 7.96% and 7.68%， and the relative safe moisture contents were 13.05%， 11.99%， 11.77%， respectively. Mume Flos decoction pieces all contained two water states during the process of hygroscopic absorption at different temperatures， namely bound water T21 and free water T22. During the process of hygroscopic absorption， bound water had the largest increase in peak area. The sum of peak areas of the bound water and free water had a good linear relationship with the moisture contents， and the R2 were 0.959 9， 0.911 8 and 0.974 7 at 25， 35， 45 ℃， respectively. When Aw<0.57， T21 did not change， and the water molecular mobility remained unchanged. When Aw>0.57， T21 showed an increasing trend， and the water molecular mobility increased. The moisture contents of Mume Flos decoction pieces were 8.44%， 6.81% and 6.25% when the water molecular mobility increased at 25， 35， 45 ℃， respectively. ConclusionCombined with the theory of water activity and water molecular mobility， 6.25% is recommended as the safe storage moisture content of Mume Flos decoction pieces， this study can provide reference for determining the safe storage moisture content of other decoction pieces.

Research on a portable shielding-free ultra-low field magnetic resonance imaging system / 生物医学工程学杂志

The portable light-weight magnetic resonance imaging system can be deployed in special occasions such as Intensive Care Unit (ICU) and ambulances, making it possible to implement bedside monitoring imaging systems, mobile stroke units and magnetic resonance platforms in remote areas. Compared with medium and high field imaging systems, ultra-low-field magnetic resonance imaging equipment utilizes light-weight permanent magnets, which are compact and easy to move. However, the image quality is highly susceptible to external electromagnetic interference without a shielded room and there are still many key technical problems in hardware design to be solved. In this paper, the system hardware design and environmental electromagnetic interference elimination algorithm were studied. Consequently, some research results were obtained and a prototype of portable shielding-free 50 mT magnetic resonance imaging system was built. The light-weight magnet and its uniformity, coil system and noise elimination algorithm and human brain imaging were verified. Finally, high-quality images of the healthy human brain were obtained. The results of this study would provide reference for the development and application of ultra-low-field magnetic resonance imaging technology.

Scientific Characterization of Traditional Softening Method of Corydalis Rhizoma / 中国实验方剂学杂志

ObjectiveModern scientific methods and techniques were used to scientifically characterize the traditional softening process of Corydalis Rhizoma， so as to clarify the scientificity and rationality of the traditional process， and provide reference for inheriting the processing methods and experience of traditional Chinese medicine. MethodLow-field nuclear magnetic resonance imaging （LF-NMR/MRI） was used to characterize the water types and distribution in the softening process of Corydalis Rhizoma. Samples during the softening process was cut into thick slices and its section was observed by stereoscopic microscope. High performance liquid chromatography （HPLC） was employed to determine the content change of tetrahydropalmatine during the softening process with the mobile phase of methanol-0.1% phosphoric acid solution （60∶40， triethylamine regulated to pH 6.5） and detection wavelength at 280 nm. The determination method of softening endpoint of Corydalis Rhizoma was simulated by texture analyzer （hand pinch method）， and the softening degree of the finished products was determined after optimizing the relevant parameters. ResultLF-NMR/MRI showed that the water could penetrate through the core and distribute evenly in Corydalis Rhizoma softened by Zhangbang method. The water first entered into the medicinal material from the epidermis and stem marks in the soaking stage as the form of free water， and then penetrated into the inner core to achieve redistribution in the moistening stage. Under stereoscopic microscope， it was observed that Corydalis Rhizoma softened by the Zhangbang method could be sliced well， but the core bursting slices were easy to appear if the softening time was not enough， and the softening of samples was caused by the keratine-like powder after absorbing water. HPLC measurement showed that the loss of tetrahydropalmatine in the softening method was small， its content decreased about 5% in the soaking process， and its content was almost unchanged during the moistening process. The softening degree of Corydalis Rhizoma could be quantified by the texture analyzer， and the optimum parameters were 2 mm·s-1 of speed before test， test speed and speed after test， 20 g of the trigger force， 20% of compression degree. The compressive force of the qualified softened Corydalis Rhizoma was 12.75-15.69 N with the relative standard deviation （RSD） of 6.8%. ConclusionModern scientific methods and techniques can characterize the scientificity and rationality of the traditional processing methods， and confirm that the Zhangbang softening method has the advantages of high efficiency， convenience and small loss of index components. The texture analyzer can simulate the softening endpoint judgment method （hand pinch method）， and realize the goal from subjective experience judgment to objective technology quantification， which has a good demonstration role for the modern inheritance of traditional processing technology.

Scientific Characterization of Traditional Softening Method of Corydalis Rhizoma / 中国实验方剂学杂志

ObjectiveModern scientific methods and techniques were used to scientifically characterize the traditional softening process of Corydalis Rhizoma， so as to clarify the scientificity and rationality of the traditional process， and provide reference for inheriting the processing methods and experience of traditional Chinese medicine. MethodLow-field nuclear magnetic resonance imaging （LF-NMR/MRI） was used to characterize the water types and distribution in the softening process of Corydalis Rhizoma. Samples during the softening process was cut into thick slices and its section was observed by stereoscopic microscope. High performance liquid chromatography （HPLC） was employed to determine the content change of tetrahydropalmatine during the softening process with the mobile phase of methanol-0.1% phosphoric acid solution （60∶40， triethylamine regulated to pH 6.5） and detection wavelength at 280 nm. The determination method of softening endpoint of Corydalis Rhizoma was simulated by texture analyzer （hand pinch method）， and the softening degree of the finished products was determined after optimizing the relevant parameters. ResultLF-NMR/MRI showed that the water could penetrate through the core and distribute evenly in Corydalis Rhizoma softened by Zhangbang method. The water first entered into the medicinal material from the epidermis and stem marks in the soaking stage as the form of free water， and then penetrated into the inner core to achieve redistribution in the moistening stage. Under stereoscopic microscope， it was observed that Corydalis Rhizoma softened by the Zhangbang method could be sliced well， but the core bursting slices were easy to appear if the softening time was not enough， and the softening of samples was caused by the keratine-like powder after absorbing water. HPLC measurement showed that the loss of tetrahydropalmatine in the softening method was small， its content decreased about 5% in the soaking process， and its content was almost unchanged during the moistening process. The softening degree of Corydalis Rhizoma could be quantified by the texture analyzer， and the optimum parameters were 2 mm·s-1 of speed before test， test speed and speed after test， 20 g of the trigger force， 20% of compression degree. The compressive force of the qualified softened Corydalis Rhizoma was 12.75-15.69 N with the relative standard deviation （RSD） of 6.8%. ConclusionModern scientific methods and techniques can characterize the scientificity and rationality of the traditional processing methods， and confirm that the Zhangbang softening method has the advantages of high efficiency， convenience and small loss of index components. The texture analyzer can simulate the softening endpoint judgment method （hand pinch method）， and realize the goal from subjective experience judgment to objective technology quantification， which has a good demonstration role for the modern inheritance of traditional processing technology.

Water migration and kinetics of Arecae Semen during moistening process / 中国中药杂志

In this study, low-field nuclear magnetic resonance(LF-NMR) and magnetic resonance imaging(MRI) were employed to analyze the water distribution, status, and migration in the moistening process of Arecae Semen. Peleg model was adopted to study the water absorption kinetics of Arecae Semen moistened at different water temperatures(10, 30, and 50 ℃). The Arecae Semen samples soaked at different water temperatures all contained four water states: binding water T_(21), non-flowing water T_(22), free water T_(23), and unbound water T_(24). Non-flowing water had the largest increase in peak area during the moistening process, followed by free water. The peak areas of non-flowing water, free water, and total water were correlated with the water content(P<0.01). Therefore, LF-NMR can quickly and non-destructively predict the water content of Arecae Semen during moistening. The peak area of non-flowing water and the content of free water were correlated with the content of arecoline in the soaking solution(P<0.01), which indicated that the faster flow of non-flowing water and more free water corresponded to more arecoline dissolved. The MRI images showed that the water migration pathway varied at different soaking temperatures, and the moistening degree obtained by this means was consistent with that obtained based on traditional experience. The rate constant K_1 fitted by Peleg model decreased with the increase in water temperature, while the capacity constant K_2 showed an opposite trend. The Arrhenius equation fitting of K_1 with temperature showed that the activation energy of Arecae Semen in the moistening process was 32.98 kJ·mol~(-1). LF-NMR/MRI can be used to analyze the water status and content and determine the end moisturing point of Arecae Semen. Peleg model can accurately describe the water absorption properties of Arecae Semen in the moistening process. The findings of this study can guide the moistening optimization and mechanism research of other seed Chinese medicinal materials.

Change of moisture transformation and chemical constituents in drying/rehydration process of fresh Chinese medicines (ginseng) / 中草药

Objective: To study the changes rule of active ingredients content and moisture status during the process of dry (drying/steaming) and rehydration (decoction), which could provide technical support for optimizing the dry/rehydration conditions of Chinese medicine and scientifically determine the end point of the process, and it also provides a new scientific perspective for exploring the differences in fresh/dry/processing of traditional Chinese medicine. Methods: Low-field NMR and imaging techniques (LF-NMR, MRI) were used to determine the change of water with time; The content changes of main composition of ginsenosides in different samples were determined by HPLC. Results: The results of determination of moisture and chemical composition showed that: The fresh ginseng was steamed for 180 min. At this time, the water was saturated, the ginsenosides tended to be stable, and the content of total ginsenosides was high. When fresh ginseng and red ginseng were dried at different temperatures for 12.5 h, they were not completely dried at 40 ℃ hot-air drying; The sun-dried ginseng still contained 3.02% water at 50 ℃ hot-air drying, and the red ginseng has been dried; Both of them have been dried at 60 ℃, but the content of total ginsenosides in ginseng and red ginseng was the highest at 50 ℃. The comprehensive results showed that ginseng and red ginseng were better at 50 ℃ hot-air drying. During rehydration (decocting), the moisture content of the decoction for 60 min was fully saturated and the content of total ginsenosides was higher, better than 30 min and 120 min, which was a better decocting condition. The moisture content and total ginsenosides content of fresh ginseng were higher than those of steaming/drying/decocting ginseng, suggesting that fresh ginseng is great significance for preserving and exerting the basic state of the initial pharmacodynamics of traditional Chinese medicine. Conclusion: In this study, ginseng was used as an example. LF-NMR/MRI and HPLC techniques were used to focus on the changes of moisture and chemical contents during the drying (drying, processing) and rehydration (decocting) of traditional Chinese medicines. It provides a new technical method for the determination of the dry/rehydration end point and the optimization of process conditions for traditional Chinese medicine, and also provides a new scientific basis for the interpretation and exploration of the theory of fresh/drying/processing of traditional Chinese medicine.

Chronological low field magnetic resonance appearance of canine spinal epidural hemorrhage model

The magnetic resonance (MR) features of spinal epidural hemorrhage depending with the passage of time have a meaning in veterinary medicine. The aim of this study is to propose the characteristic MR image of spinal epidural hemorrhage using a lower field permanent magnet scanner in dogs. A total of 8 clinically normal beagle dogs, weighing about 9 kg, were allocated. After a baseline MR examination, spinal epidural hemorrhage was created. MR scanning was executed on days 1, 2, 3, 4, 5, 10, 15, 20, 25, and 30 using 0.25 Tesla low field MR. Transverse MR images were attained for image examination. T2W, T1W, fluid-attenuated inversion recovery (FLAIR), short tau inversion recovery (STIR), and T2*-GRE sequences were used. Images were compared subjectively for signal transition assessment. Spinal epidural hemorrhage models were produced positively in 8 dogs at the T12 to L2 region. Initially, the spinal cord and epidural lesions were hyper-intense on T2W and T1W images. On T2W, FLAIR and STIR images, the spinal cord lesion was steadily hyperintense. No significant and consistent hypointense signal indicating hemorrhage was seen on T2*-GRE images. This study result suggests that relatively consistent hyperinstensity on T2 and FLAIR is observed for 30 days, meanwhile T2*-GRE imaging is less useful in hemorrhage detection.

Analysis on moisture transfer laws of Chaenomeles sinensis during drying process based on low-field NMR / 中草药

Objective To study the moisture transfer laws of Chaenomeles sinensis in different drying processes. Methods Using the non-destructive and non-invasive technique of low field-nuclear magnetic resonance (LF-NMR), the transverse relaxation time (T2) inversion spectrum of C. sinensis slice was monitored under different drying methods (hot air drying, drying after evaporation, segmental drying and drying in the shade) to analyze the changes of moisture migration. Results There were three different types water that were detected in C. sinensis (free water > bound water > immobilized water). The internal water distribution and water content changed during drying process. The moisture changes were similar in hot air drying, drying after steaming, and drying in shade, the total water gradually decreased, and the combining degree between moisture and non-water components enhanced. Steaming promoted the water loss rate of C. sinensis slice, the water loss rate was higher in drying after steaming than in hot air drying, and the difference was significant (P < 0.05). During the intermittent drying, the conversion of different states of water would occur in order to return to a relatively stable equilibrium. During the low temperature drying process, immobilized water content decreased and free water content increased. The low-temperature drying has less damage to the tissue, which is more conducive to the conversion of immobilized water into free water, and thus the water dissipated faster. During the early of drying, high temperature caused tissue structure damage, the bonding force between water and non-aqueous tissue would be strengthened because of the tissue shrinkage. Conclusion The three different types water content and peak area in T2 was positively correlated. The LF-NMR technique would provide useful guides for the investigation of water distribution and variation of C. sinensis, which will provide a theoretical basis for C. sinensis processing.

Hygroscopic characteristics and modification mechanism of Gubi Granules powder by multidimensional detection and low field nuclear magnetic resonance technology / 中草药

Objective To study the hygroscopic characteristics and its modification mechanism of extract spray powders of traditional Chinese medicine (TCM) compound formula, and provide basis for the key technical improvement of TCM solid preparation. Methods Gubi extract powders were taken as a model drug. The spray-drying technology was applied to Gubi water extract stock solution, water extract alcohol precipitation intermediates, and water extract alcohol precipitation intermediates containing different surfactants to get different extract powders. The microscopic pharmaceutical properties of these aboved Gubi Granules powder were characterized by powder fluidity testing and scanning electronic microscope technology; Different surfactants were adopted to study the hygroscopicity modification of water extract of alcohol precipitation intermediates, and then low field nuclear magnetic resonance technology (LF-NMR) was introduced to analyse the content, phase, distribution, and structure information of the water molecules absorbed by the modified extract powders; The mechanism of hygroscopicity modification of TCM extract powders was explored. Results ln the spray drying process of extract powders, it can improve the powder hygroscopicity by adding with PEG1000, poloxamer 188, magnesium lauryl sulfate, etc. It was analysed by LF-NMR that the above-mentioned surfactant could decrease the moisture absorption of the extract spray powder by combining with hydrophilic groups or free water in the air. Conclusion The addition of surfactants has a good effect on the hygroscopicity of TCM extract powders, and the improvement mechanism is related to the state of water combination.

Low-field Nuclear Magnetic Resonance Relaxation Characteristics of Fatty Acids with Different Chain Lengths and Degree of Unsaturation / 分析化学

The chemical structure of fatty acid has a great influence on the relaxation characteristic of lipid.In this work,the low-field nuclear magnetic resonance(LF-NMR) relaxation characteristics of fatty acids with different chain lengths or degree of saturation were investigated firstly,and then the relaxation characteristics of binary or ternary fatty acid mixtures were studied.The result showed that except acetic acid,the T2 relaxation time and T2Wdecreased as the carbon chain length increased; but as the unsaturated degree increased,these measures all increased.For the binary fatty acid system,the T2relaxation time and T2Wof palmitic acid-oleic acid and stearic acid-oleic acid all increased as oleic acid ratio increased.While for the linoleic acid-oleic acid system,only when the oleic acid ratio was above 40%,the relaxation response changed significantly.For the ternary fatty acid system,the T2relaxation time of each linoleic acid/oleic acid/stearic acid system increased with the increase of linoleic acid ratio,while the area ratio S21decreased,and S22increased.The higher ratio of oleic acid and the change of the peak area ratio were relatively reduced,and the relative increases of T2Wchanged more slowly.

Determination of water content and moisture distribution of xiancao prescription effervescent granules by low field nuclear magnetic resonance imaging / 中草药

Objective: To determine the water content and water phase distribution of Xiancao prescription effervescent granules by a more rapid, accurate and non-destructive low-field NMR instrument. Methods: The standard curve equation of water content and FID signal amplitude was fitted by calibrating the FID signal amplitude of four different mass of manganese chloride solutions. Three parts of Xiancao prescription effervescent granules were obtained by dry and wet granulation to test their FID signals and calculated the water content of dry and wet granulation by the fitting standard curve equation; Then the results were compared according to decompression drying of pharmacopeia standard. Results: The water content of effervescent tablets was convenient and rapid, and the result was stable and accurate. Compared with the standard decompression drying method, the water content measured by low field NMR instrument was less than 0.3%. Conclusion: Due to the decompression drying method can’t be Xiancao prescription effervescent granules within the bound water completely dry, sum of effervescent granules particles inside bound water and free water instrument is measured by low-field NMR, which can clearly show an effective method for the study of physical properties of three different phase water molecules in the process of drug manufacturing.

Time-dependent low-field MRI characteristics of canine blood: an in vitro study

This study was conducted to assess time-sensitive magnetic resonance (MR) changes in canine blood using low-field MR. Arterial and venous blood samples were collected from eight healthy beagle dogs. Samples were placed in 5-mL tubes and imaged within 3 hours of collection at 1 day intervals from day 1 to day 30. The following sequences were used: T1-weighted (T1W), T2-weighted (T2W), fluid-attenuated inversion recovery (FLAIR), short tau inversion recovery (STIR), and T2-star gradient-echo (T2*-GRE). Visual comparison of the images revealed that four relatively homogenous blood clots and twelve heterogeneous blood clots developed. The margination of the clot and plasma changed significantly on day 2 and day 13. On day 2, heterogeneous blood clots were differentiated into 2 to 3 signal layers in the T2W, T1W, and especially the STIR images. Hypointense signal layers were also detected in the blood clots in STIR images, which have T2 hypo, FLAIR hypo, and T1 hyper intense signals. In all images, these signal layers remained relatively unchanged until day 13. Overall, the results suggest that hematomas are complex on low-field MRI. Accordingly, it may not be feasible to accurately characterize hemorrhages and predict clot age based on low-field MRI.

Diagnostic imaging features of normal anal sacs in dogs and cats

This study was conducted to provide normal reference features for canine and feline anal sacs using ultrasound, low-field magnetic resonance imaging (MRI) and radiograph contrast as diagnostic imaging tools. A total of ten clinically normal beagle dogs and eight clinically normally cats were included. General radiography with contrast, ultrasonography and low-field MRI scans were performed. The visualization of anal sacs, which are located at distinct sites in dogs and cats, is possible with a contrast study on radiography. Most surfaces of the anal sacs tissue, occasionally appearing as a hyperechoic thin line, were surrounded by the hypoechoic external sphincter muscle on ultrasonography. The normal anal sac contents of dogs and cats had variable echogenicity. Signals of anal sac contents on low-field MRI varied in cats and dogs, and contrast medium using T1-weighted images enhanced the anal sac walls more obviously than that on ultrasonography. In conclusion, this study provides the normal features of anal sacs from dogs and cats on diagnostic imaging. Further studies including anal sac evaluation are expected to investigate disease conditions.

The role of low-field magnetic resonance angiography in diagnosis of intracranial artery steno-occlusive disease in patients with cerebral infarction / 中国基层医药

ObjectiveTo determine the role of low-field magnetic resonance angiography(MRA) in diagnosis of intracranial artery steno-occlusive disease in patients with cerebral infarction.Methods67 cases with cerebral infarction were given low-field MRA and DSA examination.Results62 cases of cerebral infarction MRA diagnosis and DSA agree,diagnostic accuracy was 92.5％.ConclusionLow-field MRA has a good reliability in diagnosis of intracranial artery steno-occlusive disease with the advantages of safe,reliable and convenient,can provide effective instruction for treatment of cerebral infarction.

Water-Fat Imaging with Automatic Field Inhomogeneity Correction Using Joint Phase Magnitude Density Function at Low Field MRI

PURPOSE: A new inhomogeneity correction method based on two-point Dixon sequence is proposed to obtain water and fat images at 0.35T, low field magnetic resonance imaging (MRI) system. MATERIALS AND METHODS: Joint phase-magnitude density function (JPMF) is obtained from the in-phase and out-of-phase images by the two-point Dixon method. The range of the water signal is adjusted from the JPMF, and 3D inhomogeneity map is obtained from the phase of corresponding water volume. The 3D inhomogeneity map is used to correct the inhomogeneity field iteratively. RESULTS: The proposed water-fat imaging method was successfully applied to various organs. The proposed 3D inhomogeneity correction algorithm provides good performances in overall multi-slice images. CONCLUSION: The proposed water-fat separation method using JPMF is robust to field inhomogeneity. Three dimensional inhomogeneity map and the iterative inhomogeneity correction algorithm improve water and fat imaging substantially.

Evaluation of the SLAP Lesion Using a Low-field (0.2T) Magnetic Resonance System

PURPOSE: To evaluate the diagnostic capabilities of the low-field (0.2T) magnetic resonance (MR) system in the detection of the superior labrum anterior to posterior (SLAP) lesion. MATERIALS AND METHODS: One hundred fifty patients underwent magnetic resonance imaging of the shoulder over a 7-month period. Forty-six patients underwent arthroscopic surgery, and the surgical results were correlated with the findings of the MR imaging. Arthroscopic procedures were performed within a mean of 8 days after MR imaging. MR imaging of the shoulder was conducted as follows: shoulder coil; T1-weighted spin echo, coronal-oblique images; T2-weighted gradient echo, coronal-oblique and axial images; and T2-weighted spin echo, coronal-oblique and sagittal-oblique images. Prospectively, one radiologist interpreted the MR images. RESULTS: The results of surgery were as follows: SLAP II in 26 shoulders, SLAP III in 1 shoulder, SLAP IV in 1 shoulder, normal labrum in 6 shoulders. For SLAP lesions with a higher grade than type 2, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the low-field MRI were 85.7%, 55.5%, 75%, 71%, and 74%, respectively. CONCLUSION: There was relatively good agreement for the comparison of the MR results obtained using a low-field MR system with the surgical findings for identifying SLAP lesions.

The Value of Low Field Intensity MR Gradient Echo T_2~*WI in the Diagnosis of Meniscus Injury of the Knee Joint / 实用放射学杂志

Objective To explore the value of low field intensity MR GET2*WI in the diagnosis of meniscus injury.Methods 40 patients with knee injury were examined by various sequences of low field intensity MR to show meniscus.The results of surgery or arthroscopy were acted as diagnostic gold standard of meniscus tear,all samples were confirmed by pathology.Results The sensitivity,specificity and accuracy in diagnosing meniscus tear was 95.65%,92.86% and 94.32% by GET2*WI,and 84.78%,85.71% and 85.23% by FSET2WI respectively.Conclusion Low field intensity MR GET2*WI can show meniscus clearly,it is of significant in the diagnosis of meniscus injury

Diagnostic Value of the Direct Low-field MR Arthrography in the Meniscus Degeneration and Tear of Knee / 实用放射学杂志

Objective To evaluate the diagnostic value of the direct MR arthrography in the meniscus degeneration and tear of knee.Methods Thirty subjects undefined by MR imaging having meniscus degeneration and tear of knee underwent MR arthrography.The diagnostic accurate rates in meniscus degeneration and tear by using MR imaging and MR arthrography were evaluated according to the arthroscopy results.Results The diagnostic accurate rates of meniscus degeneration and tear were 80% and 96.7% by conventional MRI scan and MR arthrography respectively.Conclusion The direct low-feild MR arthrography can improve the diagnostic accuracy of meniscus degeneration and tear of knee.

The Diagnostic Value of Paramagnetic Contrast Media in MagneticResonance Imaging(MRI)of low Field(A Report of 406 Cases) / 实用放射学杂志

Objective To research paramagnetic contrast media(PCM)dose,injection speed and imaging time etc in low field MRI.Methods 406 patients with lesions spreading all over the body received Gadolinium-DTPA-enhanced scan by bolus injection with the dose of 0.1～0.15 mmol/kg within 60 seconds,and the effects of contrast-enhanced were observed.Results Among 406 patients lesions,337 cases(83%)were enhanced,9 undiscovered lesions displayed enhancement on the precontrast views,5 cases were discovered new lesions in delaying enhancement scan.Conclusion It is safe to apply the above mentioned dose and injection speed in clinic.The side-effects is small,and the development effect is good.It is especially important for lesions involving the structure of the blood brain barrier(BBB).

Accuracy of a low-field MRI in diagnosing meniscal tears / 中华创伤杂志

Objective To specify the diagnostic accuracy of low-field MRI on meniscal tears. Methods Meniscal lesions were examined by using 0.2 T MRI and checked arthroscopically in 171 cases. The results were recorded and compared. Results From the calculation of the arthroscopic findings and the results by MRI, we obtained the diagnostic accuracy rate of 95.91% for both the medial and lateral menisci, sensitivity of 95.60% for the medial menisci and 96.47% for the lateral menisci, and specificity of 96.25% for the medial menisci and 95.35% for the lateral menisci. Conclusions The low-field MRI can bring about high diagnostic accuracy for meniscal tears and has a good price-performance ratio.