[en] Objective: To study the effects of the strength and number of b values on ADC measurements of normal brain. Methods: Seven different diffusion weightings were applied in twenty normal adult brains in diffusion tensor imaging. the brain ADC maps were calculated using seven different combinations of b values based on strength (b₀b₁, b₀b₂, b₀b₃, b₀b₄, b₀b₅) and on numbers (b₀b₆. b₀b₆, b₀b₁b₆, b₀b₁b₂b₆, b₀b₁b₂b₃b₆, b₀b₁b₂b₃b₄b₆ and b₀b₁b₂b₃b₄b₅b₆). The average of the ADC was measured and compared at the caudate nucleus, posterior limb of the internal capsule, thalamus, centrum semiovale, genu of corpus callosum and splenium of corpus callosum. Results: The measured ADC was significantly decreased accompanied with increase of b values (P<0.05), but did not correlated with the b values number (P>0.05). Conclusion: The strength of b values, not numbers of b value influences measurement of ADC, which should be considered in clinical study

[en] Objective: To evaluate the change of diffusion tensor imaging (DTI) of normal human brain at different b values. Methods: DTI were performed on 28 healthy adults at b=1000 s/mm², b=2000 s/mm² and b=3000 s/mm² respectively. Diffusion tensors maps, including ADCiso and anisotropic maps, were reconstructed by analysis software provided by Philips Corporation. Signal noise ratio (SNR) and contrast between grey matter (GW) and white matter (WM) were measured. Results: Significantly increased contrast was revealed on isotropic map and ADCiso map. Significant difference was found between b=2000 s/mm² group (or b=3000 s/mm²) and b=1000 s/mm² group, P<0.001; while there was no significant difference between b=2000 s/mm² group and b=3000 s/mm² group (P>0.05). Conclusion: 1) The image quality of DTI is the best at b=1000 s/mm², while the contrast between GW and WM is poor. 2) Satisfying image quality and contrast between GW and WM are obtained on DTI at b=2000 s/mm², in which more diffusion information is provided. And in this condition, the characteristics of water diffusion in brain tissue can be well displayed. 3) There are nice contrast and worse SNR on DTI at b=3000 s/mm², which has no significant difference with the DTI at b=2000 s/mm² (P>0.05), and also extends the scan duration. In conclusion, DTI at b=2000 s/mm² may be a routine application due to better SNR and contrast. (authors)

[en] Objective: To evaluate the correlation between MRI and X-Ray discography findings and pain response at provocative discography in patients with discogenic back pain. Methods: Two hundred and fifty-six lumbar intervertebral discs in 93 patients who underwent MRI and X-Ray discography were included in this study. MR images were retrospectively evaluated regarding disc degeneration, endplate abnormalities and high intensity zone. Disc degeneration was graded according to the modified criteria of Pearce, et al. Evaluation of disc morphology was performed with X-Ray discography by using the classification of Adams, et al. Endplates and adjacent bone marrow abnormalities were classified according to Modic,et al. During discography concordant pain was regarded as positive, whereas discordant pain and no pain were regarded as negative. The data were analyzed using the Chi-square test. Results: There were 116 discs with concordant pain and 140 discs with discordant pain or no pain. of 256 discs on discography , 17 discs were type I 17 (6.6%), type II were 25 (9.8%), type III were 91 (35.5%), type IV were 77(30.1%) and type V were 46(18.0%). On MR images, discs of grade I were 23 (9.0%), grade II were 34 (13.3%), grade III were 84 (32.8%), grade IV were 85 (33.2%) and grade V were 30(11.7% ). There was positive correlation between Pearce graded of MRI and classification of Adams of discography (r=0.62, χ²=160.87, P<0.01). In 123 discs of type IV to type V on discography, 104 discs were with concordant pain. There was positive correlation between type IV-V and concordant pain(r =0.60, χ²=144.08, P<0.01). In 115 discs of I-V grade degeneration, 99 discs presented with concordant pain. There was positive correlation between IV--V grade disc degeneration and concordant pain(r=0.59, χ²=137.11, P<0.01). In 60 discs with high intensity zone (HIZ), 52 discs presented with concordant pain. There was positive correlation between HIZ and concordant pain (r=0.41, χ²= 51.93, P<0.01). In 58 discs with endplate degeneration, 51 presented with concordant pain. There was positive correlation between Modic degeneration and concordant pain (r=0. 41, χ²=52.76, P<0.01). Conclusion: In patients with chronic low back pain, MR imaging may present moderate to severe disc degeneration, high intensity zone, endplates and adjacent bone marrow abnormalities. MR findings with concordant pain can raise the diagnostic possibility of discogenic lumbar pain. Typical discography findings, fissured or ruptured disc, with concordant pain are important diagnostic evidence for discogenic lumbar pain. (authors)

[en] Objective: To evaluate the techniques of three-dimensional dynamic contrast enhanced MR angiography (3D DCE MRA)with normative timing of sequences, enhancive 3D slab thickness and subtraction in portosystemic collaterals. Methods: Before April 2003, 12 patients were performed with 75-90 mm of 3D slab thickness and 3-5 repeated sequences estimated by breath, after April 2003, 18 patients were performed with 150-180 mm of 3D slab thickness and 5 normative repeated sequences respectively at 0, 20, 40, 60 and 90 s. After subtracting selective arterial phase images from subsequent portal venous phase images, two radiologists assessed visualization of portal collaterals independently with a four - point scale for ranking of image quality in maximum intensity projection (MIP) images with and without subtraction. Results: Average scores for image quality in visualization of the portal vein with subtraction were significantly depressed compared with the scores without subtraction (2.53±0.49 versus 2.74±0.31, P<0.05). However, subtraction three dimension-maximum intensity projection (3D-MIP) gave superior visualization of portal collaterals compared with non-subtraction 3D-MIP(2.58±0.30 versus 1.63±0.50). A statistically significant difference (P<0.01) was found between the two groups of esophageal varices. Most of portosystemic shunts demonstrated in the same time as the portal vein at about 20s, but some of collaterals demonstrated in delay time. Conclusion: Subtraction 3D-MIP demonstrates portosystemic collaterals more clearly than non-subtraction; normative timing of sequences ensure against omitting varices displayed late, 3 D slab thickness provides details about paraumbilical vein and retroperitoneal collaterals. (authors)

[en] Objective: To compare the FLASH T₂ dual-echo MRI sequence with 3D TOF MRA and susceptibility-weighted imaging (SWI) for evaluation of the cerebral circulation. Methods: Eleven healthy volunteers underwent FLASH T₂ dual-echo sequence, 3D-T0F-MRA and SWI. The visibility of the cerebral arteries and deep cerebral veins was compared. Results: Most of the cerebral arteries and deep cerebral veins were equally well seen on the dual-echo sequence in comparison with the 3D T0F MRA and SWI, respectively (P > 0.05). The 3D-T0F-MRA was significantly better than the dual-echo sequence for demonstrating the A5 segment of the anterior cerebral artery, M3-M5 segments of the middle cerebral artery and P4 segment of the posterior cerebral artery (P < 0.05). The SWI was significantly better than the dual-echo sequence for demonstrating the venae chorioidea (P < 0.05). Conclusions: FLASH T₂ dual-echo can depict most cerebral arteries and deep cerebral veins. Visualization of A5, M3-M5, P4 segments of the anterior, middle and posterior cerebral arteries is better on 3D-T0F-MRA and the venae chorioidea on SWI. (authors)

[en] Objective: The purpose of our study was to investigate three dimensional dynamic contrast enhanced MR angiography(3D DCE MRA) in the detection of portosystemic collateral circulation in the falciform ligament in patients with portal hypertension. Methods: From April 2003 to July 2008, 53 portal hypertension patients with varices in the falciform ligament were evaluated with 3D DCE MRA. Two radiologists independently assessed the number, diameter, location and drainages of the portosystemic collateral circulation in the falciform ligament according to the information on the 3D DCE MRA. Results: The veins in the falciform ligament were classified into the superior and inferior groups, and both groups arise from the left trunk of the portal vein. In our study, the number of varices detected on 3D DCE MRA images varied from 1 to 3, and the diameters of these vessels varied from 0.4 to 2.6 cm. The inferior group consisted of paraumbilical/umbilical veins (47 cases), which flowed toward umbilicus and then drained upwards (n=16) including deep superior epigastric veins (n=7), superficial superior epigastric veins (n=9), downwards (n=40) including deep inferior epigastric veins (n=7), superficial inferior epigastric veins (n=33), or upwards and downwards at the same time (n=9). The superior group of vessels in the falciform ligament were directly anastomosed with the internal thoracic vessels (n=6). Conclusion: In patients with portal hypertension, 3D DCE MRA can optimally demonstrate the portosystemic collateral circulation in the falciform ligament, which includes the superior and inferior drainage groups. (authors)

[en] Objective: To discuss the value of T₂ relaxation time in the research of the biomechanics and function of cartilage of knee joint. Methods: Knees of 20 healthy adults and 19 osteoarthritis patients were examined with sagittal 8-echo sequence. The T₂ value of cartilage was calculated. The T₂ values in the superficial and deeper cartilage of femoral and tibial joint were compared, so did between the osteoarthritis patients and healthy adults. Results: The T₂ values in the superficial and the deeper tibital cartilage were (48.8±6.3) ms, (44.3±5.7) ms, respectively. The T₂ values in the superficial and deeper femoral cartilage were (52.1±5.7) ms, (47.7±5.3) ms, respectively. There was a significant difference between superficial and deeper femoral cartilage (t=3.148 and t=3.384, P<0.01). The mean T₂ value in the tibial cartilage of osteoarthritis patients was (56.0±9.1) ms and was higher than that of healthy adults. There was a significant difference between osteoarthritis patients and healthy adults (t=-3.446, P<0.01). Conclusion: T₂ relaxation time can be used in the research of the biomechanics and function of cartilage and has a application value in clinical diagnosis. (authors)

[en] Objective: To determine the value of T₁ρ MR imaging assessment of knee cartilage degeneration in osteoarthritis (OA). Methods: Twenty patients with OA of knees and twenty healthy volunteers underwent T₁ρ and T₂ mapping MR imaging. The T₁ρ and T₂ values of the patellar and femoral cartilage were calculated and compared. The spatial correlation of T₁ρ and T₂ values was analyzed using Z-scores. The Pearson correlation coefficients of T₁ρ and T₂ Z-scores were calculated in each subcompartment. Results: The average T₁ρ values of patellar (50.01 ± 4.23) ms and femoral(53.80 ± 4.38) ms cartilage in OA were significantly (P < 0.001) higher than that in healthy adults(45.12 ± 0.92) ms, (45.42 ± 0.84) ms. The tp and T₂ Z -scores of overall cartilage correlated between healthy adults (0.455 ± 0.163) and OA patients (0.548 ± 0.170). Conclusion: T₁ρ and T₂ values of cartilage in OA are increased and may provide complementary information regarding early cartilage degeneration. (authors)

[en] Objective: To discuss the value of MR T₂ mapping in the research of the biomechanics and function of cartilage of knee joint. Methods: Knees of 20 healthy adults before and after jogging and 19 osteoarthritis patients were examined with sagittal 8-echo SE sequence. The T₂ value of cartilage was selected and calculated. The T₂ values in the superficial and deep cartilage of femoral and tibial joint before and after jogging were compared, so did between the osteoarthritis patients and healthy adults. The source images were sent to the workstation to get T₂ mappings. The T₂ value of cartilage between before and after jogging was compared with paired-samples t test. The T₂ value between superficial and deep cartilage before jogging was compared with independent-samples t test, so did between the osteoarthritis patients and healthy adults. Results: The T₂ values in the superficial and the deep tibial cartilage were (48.8±6.3) ms, (44.3±5.7) ms before jogging and (43.4±5.0) ms, (40.3±6.1) ms after jogging. The T₂ values were significantly different between before and after jogging (t=6.004 and t=5.037, P<0.05). There was a significant difference between superficial and deep tibial cartilage before jogging (t=3.148, P<0.01). The T₂ values in the superficial and deep femoral cartilage were (52.1±5.7) ms, (47.7±5.3) ms before jogging and (47.2±4.5) ms, (43.6±4.1) ms after jogging. The T₂ values were significantly different between before and after jogging (t=6.169 and t=5.957, P<0.05). There was a significant difference between superficial and deep femoral cartilage before jogging(t=3.384, P<0.01). The T₂ mapping showed those changes. The mean T₂ value in the tibial cartilage of osteoarthritis patients was (56.0±9.1) ms and was higher than that of healthy adults. There was a significent difference between osteoarthritis patients and healthy adults (t=-3.446, P<0.01). Conclusion: T₂ mapping can be used in the research of biomechanics and function of cartilage and has a prelimilary value in the diagnosis of cartilage degeneration. (authors)

[en] Objective: To improve recognition and imaging diagnosis of aneurysmal bone cyst secondary to a giant cell tumor. Methods: To collect the dates of 12 patients with aneurysmal bone cyst secondary to a giant cell tumor were proved by operation and pathology from January 2003 to October 2006. Analyzed and summarized their imaging manifestations and correlation with pathohistology. Results: Six lesions were located in epiphysis and metaphysic regions of long bone. Six lesions were located in pelvis. All cases showed a cystic lesion with expanded and osteolytic, eccentric 10 cases and centric 2 cases. Four cases display trabeculate, the margin is well define with a rim of bone sclerosis in 2 cases. Magnetic resonance imaging (MRI) scans were available in 10 patients. All case showed cystic, dilated lesions with solid areas. Eight cases manifested single or multitude solid nodules in big cystic wall. Two cases appeared solid masses with multitude cysts. The sign of multitude fluid-fluid level, best seen on T₂-weighted images, was present in all patients. Seven cases emerged soft-tissue masses. MR found indicative of large amounts of hemosiderin in one cases. Eight cases were examined by spiral CT with plain scanning and enhancement scanning. Reconstructed image were CTA and 3D-MPR (three dimensions multiplanar reconstruction) imaging. All cases showed cystic, dilated lesions with solid areas. The sign of multitude fluid-fluid level was present in 6 patients. The solid areas and cystic-wall of lesions showed contrast enhancement in 8 patients. 3D-MPR imaging showed supply blood vessel of tumors in 3 cases. Arteriovenous malformation did not found in all patients. The surgeons operative findings and the gross specimens were studied in all patients. All lesions were composed of solid areas and cystic areas. The diagnosis of pathology were ABC with GCT(grade II) in 10 cases and ABC with GCT(grade III). Conclusion: Aneurysmal bone cyst secondary to a giant cell tumor is not rare. Adequately recognizing the pathologic basis of ABC, and selecting imaging techniques correctly (X-ray and MRI, or X-ray and CT) is especially important to diagnose a giant-cell tumor with secondary aneurysmal bone cyst. When an eccentric, expanded, lyric tumor with a cystic-solid lesion in epiphysis of long bone or pelvis shows multiple fluid levels, a giant-cell tumor with secondary anemysmal bone cyst components should be sufficiently considered. (authors)