Diffusion weighted imaging in bone avascular necrosis

PURPOSE: Determining apparent diffusion coefficient (ADC) changes in avscular necrosis (AVN) by using echo planar imaging (EPI) and non-Carr-Purcell-Meiboom-Gill single shot fast spin echo (non-CPMGssFSE) sequences and comparing EPI and non-CPMGssFSE sequences in terms of image quality, signal/noise ratio (SNR) and contrast/noise ratio(CNR).MATERIALS AND METHODS: Diffusion-weighted imaging (DWI) was carried out to 33 femoral head AVN of 19 AVN cases. Control group was composed of DWI of 20 femoral head of 10 of healthy volunteers. ADC values were measured by placing ROI?s on AVN lesions by the help of T1W, T2W, and FSEIR images and standart ROI?s to femoral heads of control group. Normal bone ADC and AVN lesion ADC measured by EPI and non-CPMGssFSE sequences are each compared for statistically significant difference. Statistically significant difference between ADC values of AVN lesions with different stages was investigated. EPI and non-CPMGssFSE sequences were compared in terms of image quality, SNR and CNR.RESULTS: Median of normal bone ADC values measured by EPI sequence was 413,0 ± 167,0; median of ADC values of AVN lesions was 1440,0 ± 446,0. Median of normal bone ADC values measured by non-CPMGssFSE sequence was 185,5 ± 133,2; median of ADC values of AVN lesions was 988,0 ± 432,7. ADC values of AVN lesions were statistically significantly high (p<0,01). There were no statistically significant difference between ADC values of AVN lesions with different stages (p>0,05). Non-CPMGssFSE sequence is statistically significantly better then EPI sequence in terms of image quality, SNR and CNR.CONCLUSION: Results of this work point out that DWI might contribute to work up of AVN since increased ADC values are observed in this pathologic condition. In addition, non-CPMGssFSE sequence is superior to EPI sequence in terms of image quality, SNR and CNR.