The Study Of Femoral Marrow On Magnetic Resonance Imaging

Part I: The developing marrow and epiphysis in the proximal femur: evaluation with STIR MR imagingObjective To observe the feature of age-related marrow conversion and maturation of epiphyseal cartilage and analyse the distribution of red and yellow marrow in the proximal femur on STIR MR imaging.Methods STIR and T1-weighted MR imaging of the proximal femur in 52 subjects, aged 4 month to 25 years old , were retrospectively analyzed for the distribution and appearance of red and yellow marrow. The subjects with no known bone marrow abnormalities were divided into six age groups. The signal intensity of the marrow in the proximal epiphysis, proximal metaphysis, proximal diaphysis, distal diaphysis and greater trochanter were compared with the signal intensity and homogeneity of surrounding muscle and fat and graded by two observers.Results The conversion of hematopoietic to fatty marrow in the femur followed a well-defined sequence, occurring first in the proximal epiphysis, followed by the distal diaphysis, and then greater trochanter and metaphysis. STIR associated with T1-weighted imaging can display clearly the origin of ossification center and the course of conversion from red to yellow marrow in proximal epiphysis and greater trochanter. STIR imaging showed that the early location of marrow conversion in proximal metaphysis was below physis and intertrochanter, the site of red yellow was lied in weight-bearing axis by 20 years of age. The marrow conversion of diaphysis was from distal end to proximal end, the consequence of conversion was that distal diaphysis contained yellow marrow but proximal diaphysis contained partly red marrow, which connected with the red marrow of metaphysis. The physeal cartilage had different character of signal-intensity following of increasing age. The distribution of red marrow in STIR imaging was more close to that of anatomy thanT1-weighted imaging.Conclusion STIR was a excellent sequence to display the feature of dynamic morrow conversion and epiphyseal development. The age-related distribution of red and yellow marrow on STIR imaging was more precise relatively than T1-weighted imaging in the proximal femur.Part II: MR imaging of osteonecrosis and marrow conversion induced by steroids in patients with SARSObjective To observe the MR imaging of osteonecrosis and marrow conversion in patients with severe acute respiratory syndrome treated with steroids,to analyse the osteonecrosis and marrow conversion in patients induced by steroids.Methods MR scanning was performed in 112 patients with SARS. MR imaging of femur were obtained by the short time inversion recovery(STIR) and T1-weighted spin echo technique. The marrow conversion index (%) was the ratio of the marrow signal intensity of the proximal femoral metaphysis (SM) to that of the greater trochanter (ST). The marrow conversion index = (SM/ST) × 100.Results Among 112 patients ,MR imaging in 23 cases showed osteonecrosis in double femoral head (n=13),bilateral femoral head and distal diaphysis (n=1 ) simultaneously, metaphysic (n=6), unilateral femoral head( n=l), double knee (n=1) .The lesion of osteonecrosis was located in the site of yellow marrow. 21case of osteonecrosis without marrow edema were higher value of MCI (94.47 ± 6.48 ) than the value of MCI (80.52 ± 7.58) in same number of age-matched case which were not osteonecrosis . The difference of the two groups was statistically significant (t=4.112, P<0.05) , meanwhile,the two groups were different total and average dose of corticosteroids respectively (P<0.05).Conclusions The sites of osteonecrosis in patients with SARA were located in the area of yellow marrow. The value of MCI was a important role in diagnosing and evaluating the risk of osteonecrosis in femur .Part III : Bone marrow perfusion evaluated with dynamic contrast-enhanced MR imaging : the primary study in adult hipObjective To investigate blood perfusion of hip in the normal volunteer and the patients treated with steroids, to analyse how the steroids effected on the blood perfusion in marrow.Methods 15 normal volunteer and 25 patients treated with steroids underwent MR imaging with dynamic contrast-enhanced T1-weighted imaging in hip.The region of interest (ROI) included acetabulum, femoral head and metaphysis. The following parameters had been selected: maximum percentage of enhancement at first pass (fEmax), maximum percentage of enhancement (Emax) and washout, which was used to evaluate microvessel density (MVD), the extravascular-extracellular space(EES) and vascular permeability respectively.All value of parameters were determined from enhancement time curve (ETC).Results The features of blood perfusion in marrow had been disclosed in dynamic contrast-enhanced T1-weighted imaging. The values of fEmax and Emax in three ROI were different in normal group(the value of F: 283.96 vs 235.96, P<0.05 respectively) and patients group (the value of F: 211.57, 115.44, P<0.05 respectively). The values of washout in acetabulum and metaphysic were different in two group( the value of t: 12.34, 11.90, p < 0.05 respectively). Contrast to normal group, the values of fEmax and Emax in three ROI were decrease in patients group,the significant difference were found between subjects with normal and patients group (P<0.05, respectively).Conclusion The extravascular-extracellular space (EES), microvessel density (MVD) and capillary permeability in normal subjects were different among acetabulum, femoral head and metaphysis. The blood perfusion and EES in patients treated with steroids were lower than normal volunteer in hip.Part IV: MR imaging of femoral marrow in patients with acute myeloid leukemiaObjective To investigate the MR imaging of femoral marrow in patients with acute myeloid leukemia and analyse the value of prognostic significance.Methods MR scanning was performed in106 adult patients with AML and 10 age-matched volunteers . MR imaging of bone marrow in femur were obtained by the short time inversion recovery and Tl-weighted spin echo technique.Results MR imaging showed that femoral marrow in all patients were infiltrated by leukemia cells ,but the scope of infiltration were different among patients. MR imaging of femoral marrow were classified into five patterns according to size of infiltrated marrow: grade 1, the site of diffuse lesions was in the proximal diaphysis ; grade 2 , the site of unanimous lesions was in the proximal diaphysis; grade 3, unanimous infiltration except for femoral head and greater trochanter ; grade 4 partial infiltration of femoral head and greater trochanter ; grade 5, unanimous infiltration of femur. The MRI were read by two experience radiologist. 106 cases were divided into two groups, one was distributed between grade 1 to grade 3, the other was grade 4 to grade 5. The difference of the two groups was statistically significant (P<0.05) in the rate of complete remission.Conclusions MR Imaging of femoral marrow can provide a better understanding of pathogenetic condition and prognostic significance in patients with AML.