ABSTRACT
Objective:To explore the feasibility for taking weight and body mass index (BMI) to calculate the size-specific dose estimate (SSDE) in abdomen-pelvis CT examination.Methods:512 adult patients undergoing abdomen-pelvis CT examination were retrospectively analyzed. The in-house software based on MATLAB platform were used to calculate automatically water equivalent diameter ( dw), size-dependent conversion factor ( f), SSDE, together with their respective averaged values. The correlations between age, height, weight and BMI with dw were calculated by using Spearman correlation analysis. Two regression equations were established to calculate the SSDE (SSDE weight, SSDE BMI), one for the correlation of weight with dw based on first half of these cases and the other for that between BMI with dw based on another half as the cases to be verified. With reference of the SSDE derived from the in-house software, the averaged relative differences and root-mean-square errors in SSDE weightand SSDE BMI were calculated, respectively. Results:No statistically significant correlation between age and d w ( P>0.05) was shown, but weak correlation between height and dw( r=0.260, P<0.05), strong correlation between either weight or BMI with dw( r=0.879, 0.851, P<0.05). Two regression equations were described as dw=13.808+ 0.184×weight, dw=11.142+ 0.618×BMI. The mean SSDE, SSDE weight and SSDE BMI for the verified patients were (13.55±1.66) mGy, (13.84±2.03) mGy and (13.83±2.02) mGy, respectively. As compared to actual SSDE, the averaged relative differences in SSDE weight and SSDE BMI were 1.97% and 1.87%; 0.38% and 2.75% for male patients; 4.58% and 0.43% for female patients; 0.11% and 3.32% for patients with BMI<18.5 kg/m 2;1.92% and 2.06% for those with 18.5 kg/m 2≤BMI<24.0 kg/m 2;2.57% and 1.57% for those with 24 kg/m 2≤BMI<28.0 kg/m 2;3.28% and -1.36% for those with BMI≥28.0 kg/m 2. The averaged root-mean-square errors in SSDE weight and SSDE BMI were both 0.80 mGy; 0.65 and 0.67 mGy for male patients; 0.98 and 0.59 mGy for female patients; 0.73 and 1.03 mGy for underweight, 0.74 and 0.66 mGy for normal weight, 0.85 and 0.79 mGy for overweight, and 1.10 and 1.32 mGy for obesity. Conclusions:Weight and BMI can be used as the surrogate dw to compute SSDE in adult abdomen-pelvis CT examination. However, Weight rather than BMI is more applied to male patients, and BMI is more suitable for female patients.
ABSTRACT
Objective To investigate the difference of size-specific dose estimates ( SSDEs ) based on effective diameter ( def ) and water equivalent diameter ( dw ) in coronary computed tomography angiography ( CCTA) and explore the causes. Methods A total of 99 patients undergoing CCTA were enrolled in this retrospective study. SSDEs ( SSDEd ef and SSDEdw ) were calculated in two approaches using def and dw , respectively. Mean absolute relative difference ( MARD) was computed as an index to quantify the consistency of SSDEd ef and SSDEdw . Multivariate stepwise regression analysis was performed to study the factors influencing MARD. Results The values def and dw were positively correlated with body mass index (BMI) (r=0. 869, 0. 823, P<0. 05). The median (interquartile range) of SSDEdef and SSDEdw were 12. 34 ( 11. 75, 12. 98) mGy, 13. 78 ( 13. 02, 15. 04) mGy, respectively. SSDEdef was lower by 10. 45％ than SSDEdw( Z=-8. 186, P<0. 05) . Both SSDEdef and SSDEdw were negatively correlated with BMI and dw(r=-0. 765, -0. 680, -0. 701, -0. 840, P<0. 05). MARD of SSDEdef and SSDEdw was generally at 11. 39％. No statistical significance was found in the correlation of MARD with BMI ( r=0. 031, P>0. 05) , however, positive correlation was shown between MARD and def ( r=0. 251, P<0. 05) , but negative correlation for MARD and dw(r=-0. 379, P<0. 05). With respect to the factors influencing MARD, four variables were included into the regression equation. MARD was positively correlated with the area of both air-filled lungs ( Arealow ) and soft tissues ( Areasoft ) (β=0. 634, 0. 102, P<0. 05) , and negatively correlated with the area of bone, enhanced cardiac chambers and aorta ( Areahigh ) and the CT value of air-filled lungs ( SIlow ) (β=-0. 234,-0. 343, P<0. 05) . Conclusions SSDEdef was approximately 10. 45％ lower than SSDEdw , which was predominantly influenced by the area of air-filled lungs due to the characteristics of low X-ray attenuation in CCTA.
ABSTRACT
Magnetic Resonance Imaging (MRI) can form a three-dimensional positioning anatomical imaging.By comparing the tumor volume and signal intensity changes,there is great value of MRI in the assessment of the efficacy of cervical cancer.With the development of imaging,magnetic resonance diffusion weighted imaging (DWI),magnetic resonance spectroscopy (MRS) can provide qualitative and quantitative information of the cellular level,which reflects changes in the treatment of tumor cells.Magnetic resonance imaging can predict early locally advanced cervical cancer neoadjuvant chemotherapy,thus providing an important basis for individualized treatment of patients.
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Magnetic resonance spectroscopy (MRS) of cervical cancer can detect tumor related specific metabolic compounds such as choline,choline compounds,triglyceride,etc.MRS can be used in identification of benign or malignant lesions of cervix,diagnosis of cervical cancer and monitoring the efficacy of radiotherapy and chemotherapy,etc.It will make for the clinical diagnodis and treatment of cervical cancer.
ABSTRACT
Diffusion-weighted imaging (DWI) is sensitive to identification of cervical lesions and lymph node metastasis.DWI can be used to predict and evaluate the therapeutic effect of cervical cancer.Using magnetic resonance imaging and DWI scans in the process of diagnosis and treatment of cervical cancer,which may contribute to the personalized treatment program and improve prognosis for patients.