Value of visualization of the intraparotid facial nerve and parotid duct using a micro surface coil and three-dimensional fast imaging with steady state precession with fat-suppression sequence / 中华放射学杂志

Objective To explore the value of small surface coil combine with three-dimensional fast imaging with steady state precession and fat-suppression (3D-FISP-FS) sequence in displaying intra-parotid facial nerves segment and parotid ducts.Methods The parotid regions of 18 healthy volunteers who were excluded any parotid diseases were scanned by head&neck coil (36 sides) and 4 cm small surface coil (32 sides) combined with 3D-FISP-FS sequence prospectively. The obtained original images were treated through MIP, MPR and CPR, The MRI signal characteristics of parotid region structure, the subjective score of image quality, the signal intensity ratio (SIR) of facial nerve/parotid tissue (SIR N) and parotid duct/parotid tissue (SIRD) was calculated, and the displaying rates of the facial nerves and parotid ducts were observed. Wilcoxon matched-samples signed rank sum test was used to compare the scores of head&neck coil and small coil 3D-FISP-FS sequence images, paired t test was used to compare SIRN, SIRD of the two groups, Chi-square test was used to compare of the displaying rate of the facial nerves and parotid ducts in two groups. Results Eighteen volunteers were successfully performed MRI scan of parotid gland. On 3D-FISP-FS sequence images, the parotid gland was showed slightly low signal intensity, muscle tissue was showed medium signal intensity, the vessels were showed slightly high or high signal, parotid segment of facial nerve was showed tortuous line-like high signal intensity, and parotid duct was showed curve high signal intensity, lymph nodes were showed kidney shaped, oval or spindle shaped high signal intensity structures. The subjective scores for head and neck coil and coil images were (2.0 ± 0.9) and (1.5 ± 0.7) respectively, and the difference was statistically significant (Z=-2.714, P=0.007), image quality of small coil group was better than that of head and neck coil group. The SIRN of the two groups was 1.7±0.8 and 2.1± 1.2 respectively, and the SIRD was 1.8±0.7 and 2.5±1.7 respectively, which showed a statistically significant difference between the two groups (t value was 2.978, 2.427 respectively, P value was 0.006, 0.031 respectively).All facial nerve trunks could be displayed by head and neck coil and small coil. On head and neck coil images, 25 sides of temporofacial truck, 15 sides of cervicofacial truck, 17 sides of temporofacial branches, 11 sides of cervicofacial branches, 16 sides of the parotid duct could be displayed. On small coil images, 30 sides of temporofacial truck, 28 sides of cervicofacial truck, 26 sides of temporofacial branches, 23 sides of cervicofacial branches, 27 sides of the parotid duct could be displayed, which showed a statistically significant difference (P<0.05). Conclusion Small surface coil performed better in parotid MR imaging with 3D-FISP-FS sequence than that of head and neck coil, which can simultaneous clearly display the trunk and branches of the intra-parotid facial nerves and parotid ducts.

MRI features of different sizes of small coil using a water phantom / 中华放射学杂志

Objective To explore the imaging characteristics of different sizes of MR small surface coil.Methods A water phantom with NiSO4· 6H2O for Siemens was scanned with 4 cm,7 cm and 11 cm small surface coils in Siemens 3.0 T MR system.T1WI,T2WI,three dimensional reversed fast imaging with steady state precession with diffusion-weighted(3D-PSIF-DWI) and three dimensional fast imaging with steady state precession and fat suppression(3D-FISP-FS) images were obtained.The imaging area,signal intensity (SI),standard deviation (SD) and signal-to-noise ratio (SNR) variations of different depths (from the near to the distant) were measured and compared.Curves according to the SI and SNR data were draw.SI and SNR characteristics of images obtained by L11 separately and used together with spine matrix coil were compared by using signed rank sum test.Results The signal intensity of images scanned by 4 cm,7 cm small surface coil decreased gradually in the depth of 0.2 to 2.2 cm,maintain good signal uniformity in the depth of 2.2 to 4.2 cm,and the signal intensity obtained by 11 cm coil maintain good signal uniformity in the depth of 5.2 cm.The optimum imaging widths of 4 cm,7 cm and 11 cm coil were about 7.0,8.5 and 11.0 cm.As the diameter of the coil increased,the imaging width and depth increased,but the received noise also increased.The SNR gradually reduced from the center to the edge of the coils.The imaging area increased but the local SNR decreased when using L11 coil combine with spine matrix coil,which showed a statistically significant difference (Z=-2.354,P=0.019).Conclusions A suitable size of small surface coil should be chosen according to the location and size of the organ or lesion before clinical MR examination.Other coils should be turned off to improve the SNR.

MRI diagnosis of ejaculatory duct obstruction / 中华放射学杂志

Objective To explore the MRI features of ejaculatory duct obstruction.Methods During January 2003 to Dccember 2010,transrectal ultrasonography (TRUS) was performed for 106 patients and underwent surgical treatment for ejaculatory duct obstruction.Among them,16 patients underwent MRI examination.The MRI features of ejaculatory duct obstruction in these patients were summarized.Results Ejaculatory duct cysts,ranging in size from 4 mm ×4 mm ×7 mm to 4 mm ×4 mm ×9 mm and locating in the paramedian line,were detected in 5 of the 16 patients; ejaculatory duct dilation located in the paramedian line was detected in 7 patients,with the internal diameter of 5 to 30 mm. After contrast injection,significant enhancement of the wall of the ejaculatory duct was observed in 2 patients.Mullerian duct cysts complicated with dilated ejaculatory duct and seminal vesicles were detected in 4 patients,in whom the cysts were located in the median line,ranging in size from 4 mm × 5 mm × 6 mm to 34 mm×35 mm ×44 mm,with inverted teardrop shaped pointing toward the seminal colliculus.ConclusionThe most common MRI features of ejaculatory duct obstruction are ejaculatory duct dilation and ejaculatory duct cysts.

Absolute quantification of calf muscle metabolites by proton 1H-MR spectroscopy / 中华放射学杂志

Objectiye To measure longitudinal (T1) and transverse (T2 ) relaxation time of metabolites in m. soleus (SOL) and m. tibialis anterior TA of healthy volunteers at 3.0 T through 1H-MRS and optimize measurement protocols. Methods Altogether 24 healthy volunteers were recruited in the study. All subjects signed a letter of informed consent. After divided into 2 groups randomly by the table of random number, 1H-MRS measurements with stimulated echo acquisition mode (STEAM) sequence were undertaken in SOL and TA separately. Progressive saturation method was used for T1 measurement. Spectra with 8 different TRs (770,900,1000, 1100,1200,1500,2000 and 3000ms ) were acquired with TE=20 ms.T2 time was measured by changing TE. Altogether 8 TEs (20,30,45,60,90,135,200 and 270 ms) were used with TR = 3000 ms. Metabolites' concentration was calculated through T1 and T2 correction using water as internal reference. The t test was used for statisties. Results Altogether 22 groups of data were gained ( 12 for SOL, 10 for TA ) . T1 value of water, Creatine-CH3 ( Cr3 ), Trimethyl amonium ( TMA ),extramyocellular lipid (EMCL) and intramyocellular lipid (IMCL) in SOL were ( 1384. 0 ± 36. 9 ),( 1064. 0 ± 167.0), (964. 2 ± 144. 0 ), ( 373.0 ± 46. 8 ), ( 374. 7 ± 20. 6) ms respectively and T2 value were (26.5 ±1.2), (100.2±19.3), (149. 1 ±32.7), (81.4±5.2), (84.7±4.2) ms. InTA T1 value of water, Cr3, TMA, EMCL, and IMCL were ( 1307. 0 ± 24.4), (945.7 ± 132. 0), (968.3 ± 127. 0),(372. 7 ± 39. 2), (412. 8 ±80. 2) ms respectively and T2 value were (27. 1 ± 0. 9), (135.3 ± 18. 2 ),(62.1 ± 6. 0), ( 84. 3 ± 4. 0 ), ( 90. 7 ± 3.2 ) ms. After corrected by the calculated relaxation times, the concentrations of Cr3 in SOL and TA were (33. 1 ± 3.7) and (31.7 ± 3. 1 ) mmol/kg respectively, TMA (35.2±3.2) and (32.9 ±5.2) mmol/kg, EMCL (12.2 ±5.0) and (8.9 ±4.9) mmol/kg, IMCL (9. 0 ± 2. 4) and (3.0 ± 0. 8 ) mmoL/kg. IMCL in TA was much lower than SOL with statistical significant ( t = 8. 044, P < 0. 01 ), the difference between other metabolites were not statistically significant( t = 0. 926,1. 264, 1. 542, P > 0. 05 ) . Conclusions Accurate relaxation time was measured at 3.0 T of the metabolites in skeletal muscles of healthy adult human. After corrected by the relaxation times, the absolute concentrations calculated were consistent with the reported results. Quantitative knowledge of muscle NMR relaxation time was a prerequisite for absolute quantification of metabolites using the 1H-MRS and also was useful for optimizing measurement protocols.

MRI evaluation of the histopathological characteristic of limb soft-tissue aggressive fibromatosis / 中华放射学杂志

Objective To assess the value of using MRI to evaluate the histopathological characteristic of limb soft-tissue aggressive fibromatosis (AF). Methods The MBI findings and histopathological data of 20 patients with AF were obtained and analyzed. The difference between the different signal regions in AF were compared of signal intensity in T1-weighted images, T2-weighted images and degree of enhancement. The data were processed with paired t test. The histopathology of different signal regions was observed in 6 cases on HE stain and Masson trichromic stain of AF specimen. Results (1) AF predominantly originated from the skeletal muscles (19/20), presenting as Iobulated mass with infiltrative growth(20/20) ;(2) A few claw-shaped neo-arteries(7/7) were delineated in the periphery of the mass in the 3D DCEMRA images as well as the mild tumor staining(7/7) ; (3) Based on the MRI findings, the porenchyma of 20 AF was divided into two distinct regions of structure: region Ⅰ and region Ⅱ. Region Ⅰ presented as hypointensity on both T1-weighted and T2-weighted images and no enhancement after i. v. administration of contrast. Region Ⅱ presented as mild hyperintensity on T2-weighted images and iso- or hypointensity on T1-weighted images and marked enhancement; (4) The signal intensity in T1-weighted images, T2-weighted images and degree of enhancement was 0. 10 ± 0. 02,0. 24 ± 0. 03, and ( 5.22 ± 0.42)% in region Ⅰ , respectively; and 0.79±0.04,3.05±0.08 and(151.5±8.61)% in region Ⅱ, respectively. The differences between region Ⅰ and region Ⅱ were statistically significant of signal intensity in T1-weighted images( t = 67. 37 ), and signal intensity in T2-weighted images( t = 196. 56) and degree of enhancement(t =76. 62) (P <0. 01 ) ; (5) Histologically, AF was composed of fibroblasts, fibrecytes and bundles of collagen fiber. On Massen triehromie stain, region Ⅰ was stained blue, being proven the mature collagen fibers. Region Ⅱ was predominantly composed of fibroblasts, fibrecytes and was not stained. Conclusion The region Ⅰ and region Ⅱ are the characteristic MRI manifestations of AF, and MBI precisely reflects the histopathological and biological feature of the tumor.

Parameters optimization of diffusion tensor MR imaging of the human calf at 3 tesla / 中华放射学杂志

Objective To demonstrate the feasibility of DTI in human calf with body phased-array coil and surface coil of spine as receiving coil on 3 T system, and to optimize the parameters of sequence, including slice thickness and b-value. Methods Fifteen healthy volunteers were recruited in this study and randomly divided into three groups. The DTI sequence for head was performed on calf in the first group (5 cases), and the sequence parameters were optimized based on the deficits of the raw and the post-processed DTI images. Then, different slice thickness were applied in the senond group (5 eases) to optimize the slice thickness, and this optimized parameter with the highest score based on quality of the post-processed DTI images was applied in the next step. Finally, different b values were applied in the last group to optimize this parameters. The b value with the highest score based on the quality of the pest-processed was the proper one. Results Three problems existed in the raw and the pest-processed images, when the DTI sequence for brain was used for the calf. First, the SNR of raw images is extremely low. Second, the muscle were unclear on the image with parts of signal lose, especially in the anterior tibialis muscle. Finally, the artifacts due to chemical shift and ghost are quite serious. The scores for muscle display quality with slice thickness of 4 mm , 5 mm and 6 mm were (7.0±0. 0), (8.6±0. 9) and (9.0±0. 0) score respectively, the signal less scores were (5.0±0. 0) and ( 12. 8±2. 6) and ( 13. 8±2. 2) score respectively, and the general score were (22. 0±0. 0) and (30. 1±3.8) and (31.0±4. 1 ) score respectively. The differences of above scores were significant among different slice thickness (F-value were 21. 000 and 30. 544 and 12. 390 respectively, P <0. 05 ). The muscle displaying quality, signal loss and general scores were lowest in group with 4 mm slice thickness (q-value were 4. 896.6. 120,6. 327,7. 138,3. 863 and 4. 043, P < 0. 05 ) o The scores of muscle display quality, signal loss and general for b =400 s/mm2 were (9. 0±0. 0), ( 14. 0± 2. 2 ) and ( 33.0±2. 2 ) score respectively, which were lower than those with b = 800 s/ram2 [(7.0±0.0), (6.2±2.2), (21.8±3.4) score] and b=1000 s/mm2[(7.0±0.0), (5.0±0.0), (20.6±2.2) score] (q-value were 3.873,3.873,6.650,7.672,7. 101 and 5.917, P <0.05)o The scores of muscle displaying quality, signal loss and general for b =600 s/mm2 were (8.2±1.1 ), ( 13.0± 2. 3) and ( 30. 8±3. 8 ) score respectively, which were higher than those with b = 800 s/mm2 and b= 1000 s/nun2 (q-value were 3.873, 3.873, 5.797, 6.820, 5.326 and 5.917, P <0.05).There is no significant difference between b = 600 s/ram2 and 400 s/ram2 ( q-value were 2. 582 and 0. 852 and 1. 775, P > 0. 05 ). Conclusion Our preliminary findings indicate that it is feasible to perform DTI on human calf with 3 T MR. With body phased-array coil and surface coil of spine as receiving coil, the DTI sequence were optimized to acquire enough SNB with slice thickness of 5 mm and b-value of 400 s/mm2.

MR perfusion imaging study of the hepatic hemodynamics in pigs / 中华放射学杂志

Objective To evaluate the MR perfusion imaging in measuring the hemodynamics of liver.MethodsCT and MR perfusion imaging were performed in livers of 13 pigs.The hepatic artery perfusion(HAP),portal vein perfusion(PVP),total hepatic blood flow(THBF),portal vein perfusion index(PVI),distribution volume(DV)and mean transit time(MTT)were calculated and compared respectively.Hemodynamics of the liver from two kinds of imaging was compared by paked t-test,and the relativity was analyzed by Pearson correlation analysis.ResultsIn CT and MR perfusion imaging of the 13 pigs:the hepatic artery perfusion(HAP)were(37.7±7.38)and(35.80±7.31)ml-min-1·100ml-1.the portal vein perfusion(PVP)were(123.16 35.89)and(121.40±36.81)ml·min-1·100 ml-1.the total hepatic blood flow(THBF)were(160.88±37.05)and(157.21±38.71)ml·min-1·100 ml-1.the portal vein perfusion index(PVI)were(75.95±5.21)%and(76.63±5.24)%,the distilbution volume(DV)were(35.10±11.17)%and(41.03±10.06)%。The mean transit time(MTT)were(14.08±1.40)and(14.94±1.32)s.There were no statistical differences for HAP,PVP,THBF and PVI between CT and MR perfusion imaging(t=1.263,0.926,1.225,-1.115,P＞0.05).There were no statistical differences for DV and MTT(t=-3.345,-3.200,P＜0.01).Analysis of these two kinds of imaging showed the correlation coefficient of PVP,THBF and PVI were hishly related(r＞0.85,P＜0.01).Correlation coefficient of HAP,DV and M1T were moderately related(r＞0.70,P＜0.01).ConclusionsMR perfusion Call quantify the blood flow parameters of liver accurately.It is close to that of the CT perfusion imaging.