Preliminary Study Of Clinical Application Of MR Whole Body Diffusion Weighted Imaging With Background Suppression

Part one Normal image characteristics of whole body diffusion-weighted imaging and choice of b valueObjective:To study the normal adult image characteristics of whole body diffusion weighted imaging. To investigate the appropriate b value of whole body diffusion weighted imaging. Material and Methods:39 healthy volunteers, three different weightings (b=600,800,1000s/mm2) were applied in thirteen volunteer, b=800 were applied in the others in whole body diffusion weighted imaging on 1.5T MR machine. After the completion of scan, the collected image data was imputed to SUN ADW4.2 image workstation, to carry out 3D-MIP reformation, black and white gray-scale inversion and observe the signal characteristics of each site of the whole body. According to the image evaluation standards, WB-DWI original images and 3D-MIP images was assessed by two Imaging Physicians under blind method. SPSS 11.5 was used for data analysis with FriedmanM compared a number of related samples test and Wilcoxon paired sample rank sum test.Result:1, image quality with different b values differences in the whole, the difference was statistically significant. Image quality gradually decreased, from low b value to high b value. Image quality of b=0,1000 group are poor, some slices of the image influence the diagnosis. b = 0,600 and b=0,800 the image quality difference was not statistically significant. b= 600 and b=1000, b=800 and b=1000 image quality difference was statistically significant.2, the various organs and tissues of whole body have different signal characteristics. The current WB-DWI technology is not perfect, the images still exist a certain degree of deformation and artifacts.Conclusions:1, for b=0,600; 0,800; 0,1000 three parameters, b=0,800 is more appropriate for the body diffusion weighted imaging.2, the various organs and tissues of whole body have different signal characteristics. The current WB-DWI technology is not perfect, the image still exists a certain degree of deformation and artifacts. Part two Reproducibility study of free breathing whole body diffusion weighted imagingObjective:To explore the reproducibility of apparent diffusion coefficient (ADC) measurement of the normal liver and kidneys in whole body diffusion-weighted imaging.Material and Methods:sixteen healthy volunteers underwent whole body diffusion-weighted imaging with background signal suppression (DWIBS) at b-values of 0 and 800s/mm2. The upper abdomens were scanned three times with the same parameters. All images were acquired on GE 1.5T MRI scanner. Data was imputed to SUN ADW 4.2 workstation. The ADC map was obtained by using functool soft ware and then to calculate the ADC value of liver and kidneys. SPSS 11.5 was used to analysis data. Reproducibility was assessed by ICC. In the same workstation, ADC values of the liver and kidneys were measured twice on 16 volunteers with the same scan, Using SPSS11.5 Pearson correlation coefficients analysis.Result:All patients have high quality image of whole body DWI. Three times measurements of the ADC values of the liver and kidneys are of good consistency. The intraclass correlation coefficients of Left lobe and right lobe and kidneys were 0.89,0.90,0.80,0.82respectively. Respect to the reliability of measurement error, the twice ADC measurement of the liver left lobe and right lobe and kidneys of 16 volunteers by the Pearson correlation coefficient, r values were 0.76,0.83,0.75,0.78, P values were 0.018,0.006,0.020,0.009, toα=0.05 for the standard, the results show that the values between two measurements with high correlation, measurement error is small, high accuracy.Conclusions:The measurement of ADC value of the abdominal organs such as liver and kidneys have good repeatability in free-breathing whole diffusion-weighted imaging with background signal suppression, which can be further applied to the clinical research. Part three Clinical value of whole body diffusion weighted imaging with background suppression in screening malignant tumorObjective:To study the whole body diffusion weighted imaging with background suppression (WB-DWIBS) imaging features of malignant tumors, to assess the clinical value of WB-DWIBS in screening malignant tumor.Material and Methods:32 cases of malignant tumor patients, all primary tumors and metastasis lesions were confirmed by pathology, conventional imaging or follow-up. All patients were informed consent and had no check contraindications of MRI. All patients underwent whole body diffusion weighted imaging examination; b values were 800 s/mm2. FSE T2WI was also scanned in the same time. Imputed the data to SUN ADW 4.2 Workstation and then do 3D-MIP reformation, and measured ADC value on ADC maps. WB-DWI combined with b=0 T2WI and T2WI-ADC image fusion locate the lesions. To Measure ADC value of lymph node metastases of tumor cases and ADC value of lymph nodes of normal adult control group (data come from the first part of this study).Result:Successfully collected images of all patients, the whole body MIP map show restricted diffusion lesions. WB-DWI combined with b=0 T2WI and T2WI-ADC image fusion can accurately locate the lesions. Showed high signal lesions were evident in the inverted map, which showed low signal intensity. Among 32 patients, bone metastasis was found in 14 cases, 26 cases with lymph node metastasis, visceral metastasis in 11 cases and found no false-positive lesions.One case of brain metastasis lesions showed less clear, requires a combination of T2WI conventional MR. Part of small metastasis lesions of the lung and skull metastasis lesions (< lcm) don't be displayed in WB-DWI. To measure ADC value of metastatic lymph nodes, the average was (1.39±0.23)×10-3mm2/s; the mean ADC value of normal adult control group was (1.64±0.28)×10-3 mm2/s, the difference between the two groups was statistically significant (α=0.05).Conclusions:1, Restricted diffusion tumor lesions can be clearly displayed in WB-DWI,which is an effective way in malignant tumor screening.2, WBD-DWI can accurately and sensitively shows lymph nodes, which is an effective way of whole body lymph node imaging. ADC value measurement can provide useful information for diagnosis of lymph node metastasis.3, WB-DWI requires a combination of conventional MR to help locate and find small lesions(< 1cm).