Use of MRI Apparent Diffusion Coefficient to Noninvasively Differentiate between the Histologic Grades of Meningioma.

It is well known in the literature that Apparent Diffusion Coefficient (ADC) obtained during diffusion-weighted MRI of brain is sensitive in detecting and differentiating low-grade and aggressive meningiomas. However, other studies establish no correlation between mean-ADC and ultimate classification as benign, atypical or malignant. We wanted to assess the correlation between, A. mean of MRI Apparent Diffusion Coefficient (mean-ADC) and B. meningioma biomarker Ki-67 proliferation index, in cases of both low-grade and aggressive meningioma. We also wanted to assess the sensitivity of mean-ADC for diagnosing an aggressive meningioma.METHODSWe analysed 66 surgically treated meningioma patients with complete histopathology report (HPR) in Government Medical College, Kozhikode during the period of study (Nov-2017-Oct-2018), also having a pre-operative mean-ADC value during Diffusion Weighted Imaging (DWI) investigation at the same centre. For the latter, a standard MRI brain protocol including diffusion imaging was conducted and ADC map was generated. Regions of interest (ROIs) were manually drawn within the tumour on ADC map and mean-ADC values were measured.RESULTSUsing Pearson correlation coefficient, we found a significant negative correlation between Ki-67 proliferation index and mean-ADC in meningioma cases. We also calculate 0.79 x 10-3 mm2/s being a reasonable mean-ADC cut-off value due to its sensitivity of 84% and specificity of 77% in differentiating between typical and atypical meningiomas.CONCLUSIONSThe non-invasive calculation of mean-ADC is a valid diagnostic tool. Further, mean ADC can be used as a good test to differentiate typical and atypical meningiomas. The latter is a particularly valid conclusion, since there were few results from conventional MRI studies to differentiate between various typical and atypical meningiomas.

Evaluation and prediction of therapeutic response to neoadjuvant androgen deprivation therapy for prostate cancer by diffusion weighted imaging / 中华泌尿外科杂志

Objective To evaluate the effect of neoadjuvant androgen deprivation therapy (ADT) for prostate cancer on diffusion weighted imaging base on the pathological results after radical prostatectomy.Methods Medical records of 33 patients diagnosed with prostate cancer and treated with neoadjuvant androgen deprivation therapy and radical prostatectomy between January 2016 and September 2019 at Peking University First Hospital were retrospectively reviewed.Average age of patients was 67.7 (49-81) years old.All of the patients underwent prostate MRI examination before and after neoadjuvant ADT.Results Mean prostate volume after neoadjuvant ADT is 28.5 (6.25-113.76) em3,which decreased significantly by therapy (Z =-4.458,P ＜ 0.05).Apparent diffusion coefficient (ADC) values increased significantly in tumor (1.070 ± 0.325) vs.(0.828 ± 0.291) × 10-3 mm2/s (P ＜ 0.001) and decreased in benign prostatic tissue (P ＜ 0.05).Relative changes in ADC differed significantly between low-median level ISUP group and high level ISUP group (0.315 ± 0.173) vs.(0.164 ± 0.224) × 10-3 mm2/s (P ＜ 0.05),as well as obvious reaction group and focal reaction group(0.278 ± 0.21) vs.(0.094 ± 0.119) × 10-3 mm2/s (P ＜ 0.05).Conclusions There were significant,quantitative measurable changes of ADC value in prostate cancer after neoadjuvant ADT.DWI can be used to assess the efficacy of neoadjuvant ADT for prostate cancer as well as predicting pathological features.

Evaluation Of Diffusion-Weighted Imaging And Apparent Diffusion Coefficient Mapping Using Different B-Values For Magnetic Resonanceguided Focused Ultrasound Surgery: A Preliminary Study For Uterine Fibroid And Adenomyoma

The study was taken to assess the feasibility of diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) mapping using different b-values for magnetic resonance-guided focused ultrasound (MRgFUS) treatment of uterine fibroid and adenomyoma. The contrast-enhanced T1-weighted image (cT1WI) as well as DWIs and ADC maps of different b-values (i.e. 200, 600 and 800 s/mm2) were obtained from nine fibroid and five adenomyoma patients, immediately after, and 12 months after MRgFUS treatment. The image contrast score, non-perfused volume (NPV) and NPV ratio obtained were compared to determine the feasibility of DWI and ADC mapping for MRgFUS treatment outcome evaluation. Our finding showed thatimmediately after MRgFUS treatment, the DWI acquired using 200 s/mm2 b-value gave the highest image contrast score among all other b-values. The NPV calculated from DWI of 200 s/mm2 showed the best correlation (R2 = 0.938) with post-contrast NPV. At 12 months follow-up, there was no specific b-value considered as significantly superior to others in terms of image contrast. However, the NPVs and NPV ratios obtained from all DWIs and ADC maps of different b-values were in good agreement with the post-contrast NPV and NPV ratio. We observed that the DWI, particularly obtained with a low b-value (i.e. 200 s/mm2), is feasible for delineation and quantitative volumetric evaluation of the ablated region immediately after the MRgFUS treatment. At 12 months follow-up, both DWIs and ADC maps are feasible for NPV and NPV ratio calculation.

The value of DWI and ADC of 1.5T magnetic resonance in differential diagnosis for localized prostate cancer, chronic inflammatory response and benign hyperplasia / 中国医学装备

Objective:To compare and analyze the value of diffusion weighted imaging (DWI) and apparent diffusion coefficient (ADC) of 1.5T magnetic resonance (MR) in differential diagnosis for localized prostate cancer, chronic inflammatory response and benign hyperplasia.Methods: 80 patients with localized prostate cancer were enrolled in the research. The signal to noise ratio (SNR) of DWI, ADC value and semi-quantitative classification of DWI on lesions were measured, and the diagnostic efficiencies of them were compared by using ROC curve.Results: In the 80 patients with localized prostate cancer patients, there were 52 malignant lesions and 43 benign lesions in peripheral band, and there were 31 malignant lesions and 46 benign lesions in central gland. The ADC values of prostate cancer in peripheral band and central gland were 0.91±0.12 and 0.86±0.15, respectively, and they were significantly lower than that of normal tissue (1.68±0.23 and 1.28±0.31) and benign lesions (1.24±0.21 and 1.12±0.16). The semi-quantitative classifications of DWI for benign lesions were significantly higher than that for malignant lesions in peripheral band and central gland, respectively (x2=20.88,x2=12.14;P<0.05). For the diagnostic efficiency of ADC, the sensitivities of benign and malignant lesions in peripheral band and malignant gland were 91.3% and 79.1%, respectively, and the specificities of them were 89.6% and 70.2%. And they was significant higher than the corresponding sensitivities (71.2% and 51.3%)and specificities (78.4% and 65.8%) of DWI imaging.Conclusion: Both of DWI and ADC of 1.5T magnetic resonance are the important indexes in differential diagnosis for prostate cancer, chronic inflammatory response and benign hyperplasia, while ADC value is better than DWI image in the clinical efficiency.

Development of the Multi-Parametric Mapping Software Based on Functional Maps to Determine the Clinical Target Volumes / 의학물리

To determine the clinical target volumes considering vascularity and cellularity of tumors, the software was developed for mapping of the analyzed biological clinical target volumes on anatomical images using regional cerebral blood volume (rCBV) maps and apparent diffusion coefficient (ADC) maps. The program provides the functions for integrated registrations using mutual information, affine transform and non-rigid registration. The registration accuracy is evaluated by the calculation of the overlapped ratio of segmented bone regions and average distance difference of contours between reference and registered images. The performance of the developed software was tested using multimodal images of a patient who has the residual tumor of high grade gliomas. Registration accuracy of about 74% and average 2.3 mm distance difference were calculated by the evaluation method of bone segmentation and contour extraction. The registration accuracy can be improved as higher as 4% by the manual adjustment functions. Advanced MR images are analyzed using color maps for rCBV maps and quantitative calculation based on region of interest (ROI) for ADC maps. Then, multi-parameters on the same voxels are plotted on plane and constitute the multi-functional parametric maps of which x and y axis representing rCBV and ADC values. According to the distributions of functional parameters, tumor regions showing the higher vascularity and cellularity are categorized according to the criteria corresponding malignant gliomas. Determined volumes reflecting pathological and physiological characteristics of tumors are marked on anatomical images. By applying the multi-functional images, errors arising from using one type of image would be reduced and local regions representing higher probability as tumor cells would be determined for radiation treatment plan. Biological tumor characteristics can be expressed using image registration and multi-functional parametric maps in the developed software. The software can be considered to delineate clinical target volumes using advanced MR images with anatomical images.

SNR and ADC Changes at Increasing b Values among Patients with Lumbar Vertebral Compression Fracture on 1.5T MR Diffusion Weighted Images / 의학물리

To examine among patients with vertebral compression fracture the extent to which signal-to-noise ratio (SNR) and Apparent Diffusion Coefficient (ADC) values at the lumbar vertebral compression fracture site vary on diffusion-weighted MR images according to varying b values on the 1.5T MR device. Diffusion-weighted MR images of 30 patients with compression fracture due to chronic osteoporosis who underwent vertebral MRI from Jan. 2008 to Nov. 2009 were respectively obtained using a 1.5-T MR scanner with the b values increased from 400, 600, 800, 1,000 to 1,200 s/mm2. For diffusion-weighted MR images with different b values, the signal-to-noise ratio (SNR) was assessed at three sites: the site of compression fracture of the lumbar vertebral body at L1 to L5, and both the upper and lower discs of the said fracture site, while for ADC map images with different b values, the SNR and ADC were respectively assessed at those three sites. As a quantitative analysis, diffusion-weighted MR images and ADC map images with b value of 400 s/mm2 (the base b values) were respectively compared with the corresponding images with each different b value. As far as qualitative analysis is concerned, for both diffusion-weighted MR and ADC map images with b value of 400 s/mm2, the extent to which signal intensity values obtained at the site of compression fracture of the lumbar vertebral body at L1 to L5 vary according to the increasing b values were examined. The quantitative analysis found that for both diffusion-weighted MR and ADC map images, as the b values increased, the SNR were relatively lowered at all the three sites, compared to the base b value. Also, it was found that as the b values increased, ADC values were relatively lowered at all the three sites on ADC map images. On the other hand, the qualitative analysis found that as the b values increased to more than 400 s/mm2, the signal intensity gradually decreased at all the sites, while at the levels of more than 1,000 s/mm2, severe image noises appeared at all of the three sites. In addition, higher signal intensity was found at the site of compression fracture of the lumbar vertebral body than at the discs. Findings showed that with the b value being increased, both the signal-to-noise ratio (SNR) and Apparent Diffusion Coefficient (ADC) values gradually decreased at all the sites of the lumbar vertebral compression fracture and both the upper and lower discs of the fracture site, suggesting that there is a possibility of a wider range of applications to assessment of various vertebral pathologies by utilizing multi b values in the diffusion-weighted MRI examination.

Assessment of Osteoporosis Based on Changes in SNR and ADC Values on MR Diffusion Weighted Images / 의학물리

This study tested how S/N (Signal to Noise Ratio) ratios and ADC (apparent diffusion coefficient) values vary with different T-scores in a group of patients with osteoporosis. Based on DEXA (Dual Energy X-ray Absorptiometry) T-scores for L1?L4 for two groups of subjects consisting of 30 healthy people without osteoporosis and 30 patients who came for treatment of waist (lumbar or low back) pain and were suspected to have osteoporosis as judged from the simple X-ray findings, this study classified every spine into two groups of osteoporosis and osteopenia. Signal intensity measurements were made in the four regions of L1 to L4 on diffusion-weighted MR images obtained using 1.5T MR scanner, while ADC measurements were obtained from ADC map images. As an approach for quantitative analysis, the comparison of the variances in S/N ratios and ADC values for varying T-scores in the selected regions of interest was carried out based on averaged T-scores, S/N ratios, and ADC values. Also, the variances in S/N ratios and ADC values for each of the groups of osteoporosis and osteopenia, which were classified into by T-scores, were compared. For qualitative analysis, a careful naked eye examination of signal intensity differences in the area of L4 was made on T1-weighted sagittal images for each of the healthy (normal), osteopenia, and osteoporosis groups. In the qualitative analysis, it was found that for both the osteopenia group and the osteoporosis group, as T-scores deceased, the S/N ratios on diffusion-weighted MR images also decreased, with the greatest decrease in the S/N ratio found in the osteoporosis group. Additionally, among the three groups, the lowest S/N ratio was found in the osteoporosis group. With respect to ADC map, it was found that for both the osteopenia group and the osteoporosis group, as T-scores deceased, the ADC values on diffusion-weighted MR images also decreased, with the greatest decrease in the ADC values found in the osteoporosis group. Additionally, among the three groups, the lowest ADC value was found in the osteoporosis group. On the other hand, in the qualitative analysis, the osteoporosis group showed the highest signal intensity. Additionally, among the three groups, the lowest signal intensity was found in the healthy (normal) group. It was found that as osteoporosis progressed, S/N ratio and ADC decreased, whereas signal intensity increased on T1-weighted images. Also, in diagnosing osteoporosis, MRI tests turned out to be (more) effective.