Optimal b value of diffusion-weighted imaging on a 3.0T magnetic resonance scanner in Crohn's disease

AIM: To determine the optimal b value of diffusion-weighted imaging for detecting active inflammation in Crohn’s disease.

Diffusion-weighted Single-shot Echo Planar MR Imaging of Normal Human Prostate Using Different b Values

This study examined the effect of different b values on diffusion-weighted MR imaging （DWI） of human prostate by using single-shot spin echo echo planar imaging （SE-EPI） sequences, observed the normal appearances and measured apparent diffusion coefficient （ADC） values in anatomical regions of normal prostate. Twenty-four healthy volunteers （mean age： 32 y） were studied by using a 1.5T system with a phased array surface multicoil. Two kinds of single-shot SE-EPI sequence were used to perform DWI in the prostate in volunteers, with five b values being 0, 30, 300, 500 to 1000 s/mm2. The image quality with different imaging parameters was analyzed and the ADC values in anatomical regions of normal prostate were measured. DWI of prostate was successfully obtained in all volunteers. The images were of good quality, without artifacts containing pixels within the prostate. The contrast was good between the different anatomical regions of the prostatic gland, i.e., the peripheral zone （PZ）, which exhibited higher signal intensity, and the central gland （CG）. Signal intensity contrast was related to the magnitude of b values. The ADC values in PZ and CG were （1.27±0.22）×10-3 mm2/s and （1.01±0.17）×10-3 mm2/s,respectively. The ADC values were found to be significantly higher in PZ than in CG （P〈0.05, paired t-test）. Significant differences were found between the slice-selecting component and both the read-out and phase-encoding components of the ADC values. It is concluded that SE-EPI is a suitable DWI sequence for human prostate. The contrast between PZ and CG is good when b values are low, while the diffusion and ADC values are accurate when b values are high. ADC values are higher in PZ than in CG in normal prostate. Diffusional anisotropy is present in normal prostatic tissue.

Diagnostic Value Analysis of Dynamic Contrastenhanced Magnetic Resonance Imaging (DCE-MRI) combined with Diffusion Weighted Imaging (DWI) before Breast Cancer Surgery

Objective:The objective of this study was to investigate the diagnostic efficacy of pre-operative magnetic resonance imaging(MRI)–dynamic contrast imaging(dynamic contrast-enhanced[DCE]-MRI)combined with diffusion-weighted imaging(DWI)in detecting breast cancer.Research Methodology:A retrospective study was performed to compare the results of DCE-MRI combined with DWI in 78 patients with breast cancer who were treated in our hospital between January 20 and December 2018.Results:After diagnosis,the coincidence rate of diagnosis by DCEMRI combined with DWI was significantly higher than ultrasound(91.0%vs.55.1%,respectively,P<0.05).Among the two diagnostic methods,DCE-MRI combined with DWI imaging showed more obvious tumor signals,and the difference was statistically significant(P<0.05).Conclusion:Pre-operative application of DCE-MRI combined with DWI can provide a more accurate and effective reference for surgical planning.

Evaluation of diffusion weighted imaging of magnetic resonance imaging in small focal hepatic lesions:a quantitative study in 56 cases

Diffusion-weighted imaging (DWI) as a new technique of magnetic resonance imaging (MRI) is used to detect focal hepatic lesions. This study was designed to evaluate the significance of DWI to differentiate focal hepatic lesions less than 3 cm in diameter by the quantitation of apparent diffusion coefficient (ADC) values. METHODS:DWI using 1.5T MRI scanner unit was performed with a spin-echo single-shot echo planar imaging (EPI) in 56 cases of small focal hepatic lesions, including hepatocellular carcinoma (11), hepatic metastatic tumor (15 ), hepatic cavernous hemangioma (14), and hepatic cyst (16).The ADC values of these lesions were calculated respectively. The ratios of the ADC values of lesion/liver in hepatocellular carcinomas and hepatic metastatic tumors were also estimated. RESULTS:The mean ADC values (mm2/s) were (0.93±0.06) ×10-3 in hepatocellular carcinomas, (1.09±0.18)×10-3 in hepatic metastatic tumors,(1.95±0.38)×10-3 in hepatic cavernous hemangiomas, and (3.18±0.33) ×10-3 in hepatic cysts. The ratios of ADC values of lesion/liver were 0.90±0.06 and 1.15±0.14 in hepatocellular carcinoma and hepatic metastatic tumors respectively, which were significantly different (P<0.05). CONCLUSION:The measurement of ADC values and the ratios of ADC values of lesion/liver are helpful in MR diagnosis and differentiation of focal hepatic lesions.

Diagnostic Utility of Diffusion-weighted Magnetic Resonance Imaging in Differentiating Small Solid Renal Tumors （≤4 cm） at 3.0T Magnetic Resonance Imaging

Background： The aim of this study was to assess the performance of apparent diffusion coefficient （ADC） measurement obtained with diffusion-weighted magnetic resonance imaging （DW-MRI） to distinguish renal cell carcinomas （RCCs） from small benign solid renal tumors （〈4 cm）. Methods： In this cross-sectional study, 49 consecutive patients with histopathologically confirmed small solid renal tumors, and seven healthy volunteers were imaged using nonenhanced MRI and DW-MRI. The ADC map was calculated using the b values of 0, 50, 400, and 600 s/ mm2 and values compared via the Kruskal-Wallis and Mann-Whitney tests. The utility of ADC for differentiating RCCs and benign lesions was assessed using a receiver operating characteristic curve. Multiple nonenhanced MRI features were analyzed by Logistic regression. Results： The tumors consisted of 33 cases of clear-cell RCCs （ccRCCs） and 16 cases of benign tumors, including 14 cases of minimal fat angiomyolipomas and 2 cases ofoncocytomas. The ADCs showed significant differences among benign tumors （[0.90 ±0.52] x 10 x mm2/s）, ccRCCs （[1.53 ± 0.31 ] x 10 ^3 mm2/s） and the normal renal parenchyma （[2.22 ± 0.12]x 10^-3 mmVs） （P 〈 0.001）. Moreover, there was statistically significant difference between high and low-grade ccRCCs （P = 0.004）. Using a cut-offADC of 1.36± 10 3 mm2/s, DW-MRI resulted in an area under the curve （AUC）, sensitivity, and specificity equal to 0.839, 75.8%, and 87.5%, respectively. Nonenhanced MRI alone and the combination of imaging methods led to an AUC, sensitivity and specificity equal to 0.919, 93.9%, and 81.2%, 0.998, 97%, and 100%, respectively. The Logistic regression showed that the location of the center of the tumor （inside the contour of the kidney） and appearance of stiffblood vessel were significantly helpful for diagnosing ccRCCs. Conclusions： DW-MRI has potential in distinguishing ccRCCs from benign lesions in human small solid renal tumors （〈4 cm）, and in increasing the accuracy for diagnosing ccRCCs when combined with nonenhanced MRI.