The Study Of MRI Application In Growing Cartilage And Chondroid Tumors

PURPOSE: To establish the characteristics at MRI of the normal growing cartilage of distal femurs during development and maturation and to search for the most valuable MR sequence.To explore MR application in chondroid tumors with cartilage sensitivity sequences.METERIAL AND METHODS: MR images studies in 34 volunteers aged 2-15 years who had no clinical symptoms and 17 patients with chondroid tumors .The methods are as follows:1.The examinations were carried out on two GE signa 1.5 T MR systems(Signa 1.5T HD echo,GEå’ŒSigna 1.5T MR/i).2.The scanning protocol of volunteers include: Sagittal T₁ weighted fast spin-echo(FSE-T₁W),T₂ weighted fast spin-echo(FSE-T₂W),T₂* gradient echo (T₂*GR),proton density weighted fast spin-echo (FSE-PDWI) , short inversion time inversion recovery (STIR), fat-saturation T₁* weighted three-dimensional fast spoiled gradient echo (FS-3D- T₁*- FSPGR).The scanning protocol of chondroid tumors patients include:Saggital or axial or coronal FSE-T₁W,FSE-T₂W, T₂*GR, FSE-PD, FS-3D- T₁*- FSPGR.Some added diffusion weighted imaging(DWI),b=165s/mm³, 200 s/mm³,300 s/mm³,500 s/mm³ã€‚3.Two radiologic specialist were blind to analysis the signal character- ristics of growing cartilage and chondroid tumors in all sequences.4.To evaluate SNR and CNR in all sequences.physeal cartilage/ surround tissue CNR=(MnE-MnC)/σ。MnE is the mean signal intensity of physeal cartilage; MnC is the mean signal intensity of surround tissue.The statistic methods:using SPSS11.5 software.RESULTS:1. The use of cartilage sensitive sequence in normal growing cartilage(1) The MRI characteristic of distal femurs physeal cartilage:low signal intensity in FSE-T₁WI and FSE-T₂WI; high signal intensity in T₂*GR,FSE-PDWI,STIR,FS-3D-T₁*-FSPGR.SNR in FS-3D-T₁*-FSPGR is 18.4±6.92,the highest of the 6 sequence. There were statistic significance among the sequences.(2) CNR of FS-3D-T₁*-FSPGR is the highest between epiphyseal cartilage and physeal, epiphyseal cartilage and metaphyseal.(3) Epiphyseal cartilage has two layers in FSE-T₂WI,T₂*GR,FSE-PDWI,STIR.The inner thin layer is high signal;the outer layer is broad and little lower signal than inner layer and articular cartilage.CNR between inner layer epiphyseal cartilage and outer layer,outer layer epiphyseal cartilage and articular cartilage is the highest in STIR.2. MR character of chondroid tumorsa) Chondroblastoma: homogenous hypointensity in FSE-T₁WI;a little lower intensity in FSE-T₂WI;hyperintensity in T₂*GR, FSE-PD and STIR; intermediate high signal intensity in FSE-PDWI and STIR .Blur high signal in FSE-PDWI and T₂*GR sequences around chondral lesions in 1 case.b) Enchondroma: low signal in FSE-T₁WI and FS-3D-T₁*-FSPGR; slightly high signal in FSE-T₂WI and FSE-PDWI; in T₂WI,brilliant high signal in and T₂*GR.Septa can be seen in FSE-T₁WI and T₂*GR.c) Ostochondroma: cartilage cap is low signal in FSE-T₁WI and FS-3D-T₁*-FSPGR; slightly high signal in FSE-T₂WI and FSE-PD; brilliant high signal in and T₂*GR.d) Chondrosarcoma: there is a soft tissue mass around diaphysis.The mass signal is hetergenous and lobular.intermediate high signal in FSE-PDWI, the same signal with muscle in FSE-T₁WI and T₂*GR,high signal in FSE-T₂WI,low signal in FS-3D-T₁*-FSPGR.The primary chondrosarcoma is obvious enhancement,but hetergenous.CONCLUSION:1.Physeal cartilage is high-signal intensity in FSE-PDWI, T₂*GR, FS-3D-T₁*- FSPGR,STIR sequences. SNR in FS-3D-T₁*-FSPGR is the highest. There is the highest value of CNR between physeal and surroundtissue in FS-3D-T₁*-FSPGR. FS-3D-T₁*-FSPGR is the best sequence to image physeal cartilage.2.It's the first time to use STIR for imaging growing cartilage.STIR is not the best sequence to image physeal cartilage,but it has the highest CNR between inner layer epiphyseal cartilage and outer layer,articular cartilage and outer layer epiphyseal cartilage.3.It's the first time to applicate cartilage sensitive sequences in chondroid tumors.These sequences can supply different information in diagnosis.