[en] Objective: To study the radiological features and biomechanics of stress fracture. Methods: The X-ray, CT, MRI, and ECT signs in 20 cases of stress fracture and its correlation to biomechanics were analyzed. Results: Of the 20 cases, 14 cases occurred in the tibia, 2 cases in the metatarsal bone, 1 case in the rib, 1 case in the neck of femur and ribs, 1 case in the middle-inferior part of the femur, and 1 case in the fibula. Tow early cases of stress fracture demonstrated a characteristic sign of 'gray cortex'. The spherical or abnormal generation of bony callus and periosteum proliferation that demonstrated 'double cortex' sign in 2 cases were the sign of bone remodeling and the 'button sign' was the sign of bone healing. CT scan could clearly show the pathologic changes of bone and the soft tissue edema. Bone callus showed low signal on T₁WI and slight high signal on T₂WI. The area of bone edema on MRI that demonstrated low signal on T₁WI and high signal on T₂WI was larger than that on CT. MRI showed a linear band of low signal on both T₁WI and T₂WI in the area of bone fracture. ECT showed a focal area of increased uptake in the abnormal areas. The areas of bone stress fracture were characteristic and accorded with the biomechanical weak area in the bone. Conclusion: Stress fracture occurs in the special parts of the bone and has characteristic imaging features. X-ray should still be used to find the fracture of bones in the first inspection. CT and MRI are very helpful in the differentiation. Although sensitive, bone scan has lower specificity than either CT or MRI. (authors)

[en] Objective: To analyze the technical characteristics of sliding multi-slice magnetic resonance imaging (SMS-MRI), and to evaluate the value of staging ovarian carcinoma by SMS-MRI. Methods: Pre-operative SMS-MRI of chest, abdomen and pelvis was performed on 15 patients with ovarian carcinoma. Sequences included TSE T₂WI, SMS TIRM and fat-suppressed contrast-enhanced SMS FLASH. The SMS-MRI was analyzed and staged according to FIGO's classification by two radiologists. The location of tumor, local invasion of uterus and fallopian tube or other pelvic tissues, peritoneum metastasis, lymph node metastasis and distal metastasis were recorded. The results were compared with operative and pathological findings. Results: The pathological diagnosis was serous cystadenocarcinoma (9), mucinous cystadenocarcinoma (2), endometrioid carcinoma (2), clear cell carcinoma (1) and granular cell carcinoma (1) at stage II (2), stage III (10) and stage IV (3). The accuracy of SMS-MRI staging was 100% (15/15). The tumor location, involvement of uterus and fallopian tubes as well as distant metastasis were accurately demonstrated by SMS-MRI. Conclusion: SMS-MRI can be a faster one-stop examination with good image quality. SMS-MRI is an alternative imaging method of staging ovarian carcinoma. (authors)

[en] Objective: To investigate the applicative value of multi-slice CT (MSCT) perfusion imaging on quantitative assessment of tumor angiogenesis before and after interventional therapy and monitoring the early interventional therapeutic effect in malignant soft-tissue tumor. Methods: Twenty-four New Zealand white rabbits successfully implanted VX₂ tumor in the unilateral proximal thigh were divided into two groups (twelve per group) at random and performed conventional CT plain scan and perfusion scan 14 days after implantation and 3 days after interventional therapy respectively. The values of blood flow (BF), blood valume (BV), mean transit time (MTT) and premeability surface (PS) of VX₂ tumors and normal muscular tissues were computed and the differences among them were analyzed. Meanwhile, correlative analysis between perfusion parameters and micro-vessel density(MVD) counts, average A value of vascular endothelial growth factor(VEGF) was done. Results: Before interventional therapy, the values of BF, BV, MTT and PS of VX₂ tumors in interventional group were (303.3 ± 69.9) ml· 100 g^-1·min^-1, (7.02 ± 3.10) ml/100 g, (1.99 ± 0.28) s and (65.9 ± 9.4) ml·100 g^-1·min^-1 respectively. Compared with the parametric values of normal muscular tissues, there were significant differences between them (F value was 4285.82, 1867.46, 413.04 and 698.42 respectively, P<0.01). There were no significant differences of the above parametric values between interventional group and the control group (F value was 2.47, 2.03, 0.02 and 0.53 respectively, P>0.05). The values of MVD counts, average A value of VEGF of VX₂ tumors in interventional group were 50.1 ± 4.1/HP and 0.352±0.011 respectively. There were no significant differences between interventional group and the control group (F value was 0.02 and 0.19 respectively, P>0.05). Three days after interventional therapy, the values of BF, BV, MTT, PS, MVD and VEGF of VX₂ tumors in interventional group were (7.5 ± 2.4) ml· 100 g^-1·min^-1, (1.20 ±0.23) ml/100 g, (3.29 ± 0.57) s, (4.0 ± 1.5) ml·100 g^-1·min^-1, 16.0 ± 2.4/HP and 0.215 ± 0.008 respectively. Compared with the values of pre-interventional therapy and the control group, there were significant differences among them (P<0.01). Additionally, the values of BF, BV, PS in VX₂ tumors had a significant positive correlation with MVD counts, average A value of VEGF (r>0.7, P<0.05), however, the value of MTT had no significant correlation with MVD (P>0.05) but had a significant negative correlation with average A value of VEGF (r=-0.78, P<0.05). Conclusion: MSCT perfusion imaging is a functional imaging technique that is capable of quantitative assessment to tumor angiogenesis, blood perfusion and vascular permeability, which can evaluate the early interventional therapeutic effect in malignant soft-tissue tumor invasively and accurately. (authors)

[en] Objective: To observe the MR imaging of bone marrow in myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML), and to reveal the rule of bone marrow infiltration and the role of MRI in diagnosing and predicting the prognosis of myelodysplastic syndromes. Methods: Thirty patients received MRI after the diagnosis based on clinic and FAB subtype study, including 16 with MDS and 14 with AML. MR image was obtained by T₁-weighted spin echo and shot time inversion recovery in pelvis and femur. The examining results of morphology and blood routine were collected at the same time. 30 age-matched volunteers were selected as controls. Results: The MRI appearance was classified into their patterns based on scope of focus. MRI patterns from grade 1 to grade 3 was observed in patients with MDS. All patients with AML distributed in grade 2 to grade 3. The distribution of patterns had no significant difference between MDS and AML (P>0.05). The marrow ratio had significant difference among MDS, AML, and controls (P<0.05). The MRI grade was consistent with the clinic diagnostic indexes. Conclusion: MRI can provide a better understanding of the difference between MDS and AML. MRI can estimate the extent of disease in the marrow as a whole. MRI of bone marrow can provide imaging basis in diagnosis and predicting the prognosis for patients with MDS

[en] Objective: To study MRI features and the pathologic basis of pigmented villonodular synovitis (PVNS) and the corresponding biophysics mechanism of the abnormal signal on diffusion weighted imaging (DWI). Methods: MRI findings in 7 cases with PVNS and the ADC value of the lesions on DWI were analyzed, and a comparison with surgical and pathological results was made. Results: Of the 7 cases, 5 were the diffuse form (4 cases in the knee joint, 1 case in the shoulder joint). The main MRI signs were as follows: the diffused synovial proliferation demonstrated as low signal on T₁WI and high signal on T₂WI; hemosiderin deposition in the thickened synovium was revealed as low signal on both T₁WI and T₂WI; hydrarthrosis of the knee joint was present in 4 cases as low signal on T₁WI and high signal on T₂WI; the involvement of meniscus occurred in 3 cases and cruciate ligament in 2 cases as nodulated low signal on T₁WI and high signal on T₂WI; intra-articular cartilage and bony erosion were showed in 4 cases (knee joint in 3 cases, shoulder joint in 1 case); small cystic destruction of the femur occurred in 1 case. Two cases were the localized form (1 in the knee joint, the other in the hip joint). It mainly demonstrated as the nodulated proliferation of the synovium and hemosiderin deposition in the thickened synovium, which showed low signal on both T₁WI and T₂WI. One case showed hydrarthrosis of the knee joint and small cystic destruction of the femur. The hydrarthrosis, synovial proliferation, and bony erosion were demonstrated as high signal lesions on DWI. The average ADC values of the three lesions were 2.750x10^-3 mm²/s, 0.522x10^-3 mm²/s, and 0.559x10^-3 mm²/s, respectively. Conclusion: The nodulated and villose proliferation of the synovium and hemosiderin deposition within villonodules are the typical MRI signs of PVNS, which is of specific value in the diagnosis. DWI can reflect the histologic composition of the tissues comprising the PVNS lesions. The ADC values of the lesions usually decrease, and the value of which in differential diagnosis needs further study

[en] Objective: To evaluate the clinical value of the diffusion tensor imaging (DTI) in lumbar' disc annulus fiber's diseases. Methods: Fifty six subjects including normal volunteer (n=10), patients with lumbar disc herniation (LDH) (n=24), and with herniated intervertebral disc (HID) (n22) were performed with MR scan. The DTIs were obtained in each subject. The DTI source images were sent to the work station and postprocessed Fiber Tracking (FT) picture, DCavg picture, and FA picture. Results: The normal disc annulus fibrosus presented a continuous and integrity circulus in FA picture and DCavg picture, the DCavg value and FA value were uniform, DCavg was(0.34±0.13) x 10^-9 mm²/s; FA was 0.64±0.22. FT picture demonstrated the annulus fibrosus' appearance was continuous and integrity. The DCavg value and FA value in LDH group was (0.29 ± 0.10) x 10^-9 mm²/s and 0.53 ± 0.22, they had no significant difference with normal group (P>0.05). Seven cases in LDH group and 9 cases in HID group were found in FT picture. The mean DCavg value in annulus fibrosus disruption was significantly larger (1.01 ± 0.10) x 10^-9 mm²/s and the mean FA value (0.15 ± 0.03 )was significantly smaller than those in normal place (P<0.01). Conclusion: DTI can noninvasively display the lumbar disc anulus fibrosus's morphous and integrity and demonstrate anulus fiber disruption. As an effective supplement of conventional MRI, DTI can offer a precise guidance for treatment. (authors)

[en] Objective: To determine if diffusion tensor imaging (DTI) and muscle fiber tracts of muscle disease are feasible. Methods: Twenty Newzealand white rabbits were implanted with 0.2 ml VX₂ tumor tissue suspension in the right proximal thighs. MRI and DTI were performed on these rabbits and DTI of muscle fiber tracts in the muscles around the lesions were reconstructed. The fractional anisotropy(FA) and volume ratio anisotropy(VrA) of the tumor and the normal muscle were analyzed. The correlation study between MRI and pathological findings was done. Results: All experimental animal models of rabbit VX₂ soft tissue tumors were successfully established. The difference of FA between the central parenchyma area and the necrosis area, the peripheral area of the tumor, the adjacent and contralateral normal muscle was statistically significant (P<0.01). The VrA of the central parenchyma area of tumors had statistical difference with the necrosis area of tumors, the adjacent and contralateral normal muscle had difference (P<0.01), but had no statistic difference with the peripheral area of tumors (P>0.05). The difference of FA and VrA between the adjacent and contralateral normal muscle was not statistically significant (P>0.05). The arrangement of normal muscle was regular on DTI of muscle tract. The muscle around the tumor lesions was infiltrated and destructed, which demonstrated irregular and interrupted muscle fiber on muscle tractography. Conclusion: DTI is advantageous to demonstrate the structure of soft tissue tumors and its border, which should be helpful in the structure and function research of muscle, as well as in the diagnosis of muscle diseases. (authors)