Magnetic Resonance Imaging Apparent Diffusion Research Articles

Development of a prognostic model for diagnosis of prostate cancer based on radiomics of biparametric magnetic resonance imaging apparent diffusion coefficient maps and stacking of machine learning algorithms

Development of a prognostic model for diagnosis of prostate cancer based on radiomics of biparametric magnetic resonance imaging apparent diffusion coefficient maps and stacking of machine learning algorithms

Values of magnetic resonance imaging apparent diffusion coefficient for prognostic evaluation and pathological typing of patients with breast cancer

Values of magnetic resonance imaging apparent diffusion coefficient for prognostic evaluation and pathological typing of patients with breast cancer

The very low magnetic resonance imaging apparent diffusion coefficient (ADC) measure of abscess is likely due to pus's specific T2 relaxation time.

The very low magnetic resonance imaging apparent diffusion coefficient (ADC) measure of abscess is likely due to pus's specific T2 relaxation time.

Radiomics Features Based on MRI-ADC Maps of Patients with Breast Cancer: Relationship with Lesion Size, Features Stability, and Model Accuracy.

Objective:To predict breast cancer molecular subtypes with neural networks based on magnetic resonance imaging apparent diffusion coefficient (ADC) radiomics and to detect the relation of lesion size with the stability of radiomics features.Methods:This retrospective study included 221 consecutive patients (224 lesions) with breast cancer imaged between January 2015 and January 2020. Three sample size configurations were identified based on tumor size (experiment 1: all cases, experiment 2: >1 cm3, and experiment 3: >2 cm3). The tumors were segmented by three observers based on diffusion-weighted imaging-registered ADC maps, and the volumetric agreement of these segmentations was evaluated using the Dice coefficient. Stability of radiomics features (n=851) was evaluated with intraclass correlation coefficient (ICC, >0.75) and coefficient of variation (CoV, <0.15). Feature selection was made with variance inflation factor (VIF, <10) and least absolute shrinkage and selection operator regression. Outcomes were identified as molecular subtypes (Luminal A, Luminal B, HER2-enriched, triple-negative). Neural network performance was presented as an area under the curve and accuracies.Results:Of the 851 radiomics features, 611 had ICC >0.75, and 37 remained stable in the first experiment, 49 in the second, and 59 in the third based on CoV and VIF analysis. High accuracy was demonstrated by the Luminal B, HER2-enriched, and triple-negative models in the first experiment (>80%), all models in the second experiment, and HER2-enriched and triple-negative models in the third experiment.Conclusions:A positive stability is indicated by an increased lesion size related to radiomics features. Neural networks may predict moleculer subtypes of breast cancers over 1 cm3 with high accuracy.

Magnetic resonance imaging apparent diffusion coefficient in lymphomas and its dependence on a number of technical and clinical factors

The purpose of this study was to determine the value of apparent diffusion coefficient (ADC) in various morphological variants of lymphomas, to study dependence of ADC on the anatomical location of lesions and technical scanning parameters to establish the usefulness in differentiating normal and involved lymph nodes (LN).Whole body MRI with diffusion-weighted imaging (DWI) was performed in 209 patients with lymphoma before treatment. A target LN was selected and ADC determined in each patient.The ADC value does not depend on the use of the parallel imaging technique (p= 0.56), higher when using built-in compared to superficial coil (p&lt; 0.0001), higher when using respiratory triggering than free breathing (p&lt; 0.02). The highest ADC values (х10-3mm2/s) were obtained in the involved LN of the lung hilar (1.429 ± 0.396) and mediastinum (1.338 ± 0.313), lower values (p&lt; 0.01) - in the LN of the abdomen (1.011 ± 0.298), axillary (0.840 ± 0.196), neck (0.834 ± 0.259), inguinal (0.753 ± 0.128) and iliac (0.738 ± 0.129). Depending on the morphological variant of lymphoma, the highest ADC value was obtained in Hodgkin lymphoma - 1.168 ± 0.372 (p&lt; 0.0002). ADC in diffuse large B-cell non-Hodgkin lymphoma was 0.951 ± 0.320, indolent non-Hodgkin lymphomas - 0.756 ± 0.246, mantle zone non-Hodgkin lymphoma - 0.759 ± 0.211.In conclusion, DWI in lymphoma should be performed using surface coil, parallel imaging, and free breathing. Statistically significant differences in ADC were found depending on the anatomical location of the lesions and the morphological variant of lymphoma. Given the dependence of ADC on various technical and clinical factors, it is not possible to establish a single threshold value for differentiating involved and normal LN. The use of the LN size criterion for this purpose is the most optimal in lymphoma.

Correlation of the magnetic resonance imaging apparent diffusion coefficient with the count of cellularity in the histological material in different morphological types of lymphomas

Objective:to evaluate the correlation between the values of the magnetic resonance imaging (MRI) apparent diffusion coefficient (ADC) and the count of cellularity in histological material and to establish a relationship between the cellular structure and the prognostic properties of MRI with diffusion-weighted imaging (MRIDWI) in various morphological types of lymphomas.Materials and methods.101 patients with morphologically verified lymphoma (Hodgkin lymphoma (HL) — 52 patients, non-Hodgkin lymphomas (NHL) — 49) underwent whole body MRI-DWI before treatment and ADC measurement in the target lesion. An excisional biopsy of the lesion was performed from the same anatomical area and the count of cellularity in the histological material was determined.Results.In HL, aggressive NHL and diffuse large B-cell lymphoma (DLBCL), ADC is statistically significantly higher, and cellularity is lower than in indolent NHL and cells of the mantle zone of NHL. We have found an inverse correlation between the values of ADC and cellularity in aggressive NHL (ρ = -0.47, p = 0.005) and DLBCL (ρ = -0.48, p = 0.006).Conclusion.ADC values depend on the cellular structure of the lymphomas. The correlation of ADC and cellularity values of various morphological types of lymphomas allows explaining the prognostic properties of ADC.

Influence of 4-week or 12-week glucocorticoid treatment on metabolic changes in patients with active moderate-to-severe thyroid-associated ophthalmopathy.

Thyroid‐associated ophthalmopathy (TAO) is a serious, progressive, vision‐threatening and difficult‐to‐treat organ‐specific autoimmune disease. The course, therapeutic effects and prognosis of moderate to severe TAO vary greatly. High‐dose intravenous glucocorticoid (IVGC) therapy is considered a first‐line treatment for active moderate‐to‐severe TAO, but there is still insufficient evidence regarding the treatment duration. Long‐term IVGC therapy can influence the metabolism of glucose, lipids, and bone. This study was designed to compare changes in metabolic and immunological indexes as well as the magnetic resonance imaging apparent diffusion coefficient (ADC) of the extraocular muscles after 4 and 12 weeks of IVGC therapy. Forty‐eight patients with active moderate‐to‐severe TAO were included in this retrospective cohort study. Metabolism and immunological indexes were measured before and after therapy. The ADC and clinical activity score (CAS) were used to evaluate the efficacy of treatment in these patients. We found that the patients in the 12‐week group had increased fasting plasma glucose (p = 0.004), glycated hemoglobin (p = 0.028), total cholesterol (p < 0.001), and low‐density lipoprotein (p < 0.001) after therapy. The patients in both groups had reduced bone metabolism markers after therapy. Thyroid peroxidase antibody and thyrotropin receptor antibody levels decreased after treatment in both groups (p < 0.001). A significant decrease in thyroglobulin antibody levels was found in the 4‐week group (p = 0.006). The change in the ADC was higher in the 4‐week group than in the 12‐week group (p = 0.014). However, there were no significant differences in CAS values between the two groups. Therefore, 4‐week IVGC therapy was recommended for patients with TAO with glucose and lipid disorders.

Which imaging method is better for the differentiation of adenomyosis and uterine fibroids?

ObjectiveThe paper compares shear wave elastography (SWE), strain elastography (SE) and magnetic resonance imaging apparent diffusion coefficient (MRI ADC) values, to evaluate their efficacy for differentiating between adenomyosis (AM) and uterine fibroids (UF). MethodsPatients who were scheduled for hysterectomy for AM or UFs, with a preliminary diagnosis, were additionally evaluated before surgery by transabdominal and transvaginal ultrasound elastography. SE of patients were evaluated by transvaginal ultrasound, and SWE of patients and control subjects were evaluated by transabdominal ultrasound. Then, the patients with a definitive histopathological diagnosis as AM or UFs were evaluated retrospectively and compared to the control group without myometrial pathology. In addition, MRI images of patients with UFs and AM were examined for ADC values. ResultsThe results of 98 patients in the UF group, 37 patients in the AM group, and 40 volunteers with a healthy myometrium in the control group were compared. There were no statistically significant differences in age and body mass index between the groups (P > 0.05). Uterine size was significantly higher in the UF and AM group than the control group (P < 0.001). A statistically significant difference was found between strain ratio (mean), strain ratio (max), and ADC values between the UF and AM groups (P < 0.001 for all three). There was a statistically significant difference in elastography scores distribution between the groups (P < 0.001). There was a statistically significant difference between the UF and control (P < 0.001) and between the UF and AM (P < 0.001) groups in terms of SWE (kilopascal (kPa)) averages (P < 0.001). We found that none of these discrimination methods were statistically superior to each other in differentiating the UFs from the AM. ConclusionIn the differentiation of myometrial pathologies in gynecological imaging, both SE and SWE are cheaper, provide faster results, are non-invasive and easy to apply, and hence are as promising as the more expensive MRI ADC. Our study is the first to use both modalities of elastography and MRI ADC values together, compare these methods with each other and confirm the results pathologically.

Correlation of Magnetic Resonance Imaging Apparent Diffusion Coeffecient Values with Treatment Outcome in High Grade Glioma Patients Undergoing Concurrent Chemoradiation

High grade gliomas are aggressive malignancies characterized by high proliferation rate, extreme heterogeneity with potential to develop resistance to radiation and chemotherapy as well as short survival period. MRI is considered to be the best imaging modality for brain tumors. ADC values has the potential to serve as an imaging biomarker for response assessment, since it can provide dynamic objective information about tissue and tumor cell density. Low ADC values of diffusion weighted MRI in brain is a negative prognostic variable for patients undergoing radiotherapy. MRI ADC values could provide a reasonably good opportunity to predict the response earlier than conventional methods and thereby could help in individualizing therapy. A total of 22 consecutive postoperative high-grade glioma patients (20 glioblastoma and 2 anaplastic astrocytoma) were analyzed. The ADC values of the tumor on pre-radiotherapy and post radiotherapy MRI were determined from several regions of interest defined in the tumor by “segmentation technique”. This technique expected to give more information, since it measures differing values within the tumor, which would be otherwise averaged out. Radiotherapy along with concurrent chemotherapy was undertaken in all cases. All the patients had at least one post radiotherapy MRI done. Kaplan -Meir survival curves, log rank test were used to evaluate the prognostic factors. The 18 months survival rates associated with low (<0.7x10-3mm2/sec) and high (>1.0x10-3mm2/sec) minimum pre-RT ADCs were 5 and 18 months respectively (p=0.004).The median follow-up period is 13 months. The patients with post RT minimum ADC value below 0.9 x10-3mm2/sec had median survival of 6 months and patients with post RT minimum ADC value above 0.9x10-3mm2 /sec had median survival of 15 months (P value = 0.040). The patients with post RT overall ADC value below 1.3 x10-3mm2/sec had median survival of 6 months and patients with post RT overall ADC value above 1.3x10-3mm2 /sec had median survival of 15 months (P value of 0.04). In high grade glioma patients who have tumors with low ADC values are expected to have have poorer prognosis. In our study of segmentation technique, the minimum ADC values showed better correlation with survival than overall ADC. The minimum ADC at pre-treatment MR imaging is a useful clinical prognostic biomarker. The minimum and overall ADC values from post treatment MR imaging are useful for patient risk stratification after completion of chemo radiation.In future, advanced imaging with new algorithms for 3D ADC mapping diffusion MRI might help in identification of the resistant sub-volumes within the tumor dynamicallly which can lead to biological targeted therapy.

Modulating the water channel AQP4 alters miRNA expression, astrocyte connectivity and water diffusion in the rodent brain

Aquaporins (AQPs) facilitate water diffusion through the plasma membrane. Brain aquaporin-4 (AQP4) is present in astrocytes and has critical roles in normal and disease physiology. We previously showed that a 24.9% decrease in AQP4 expression after in vivo silencing resulted in a 45.8% decrease in tissue water mobility as interpreted from magnetic resonance imaging apparent diffusion coefficients (ADC). Similar to previous in vitro studies we show decreased expression of the gap junction protein connexin 43 (Cx43) in vivo after intracortical injection of siAQP4 in the rat. Moreover, siAQP4 induced a loss of dye-coupling between astrocytes in vitro, further demonstrating its effect on gap junctions. In contrast, silencing of Cx43 did not alter the level of AQP4 or water mobility (ADC) in the brain. We hypothesized that siAQP4 has off-target effects on Cx43 expression via modification of miRNA expression. The decreased expression of Cx43 in siAQP4-treated animals was associated with up-regulation of miR224, which is known to target AQP4 and Cx43 expression. This could be one potential molecular mechanism responsible for the effect of siAQP4 on Cx43 expression, and the resultant decrease in astrocyte connectivity and dramatic effects on ADC values and water mobility.

Multiparametric MRI Apparent Diffusion Coefficient (ADC) Accuracy in Diagnosing Clinically Significant Prostate Cancer

To evaluate the accuracy of multiparametric magnetic resonance imaging apparent diffusion coefficient (mpMRI ADC) in the diagnosis of clinically significant prostate cancer (PCa). From January 2016 to December 2016, 44 patients who underwent radical prostatectomy for PCa and mpMRI lesions suggestive of cancer were retrospectively evaluated at definitive specimen. The accuracy of suspicious mpMRI prostate imaging reporting and data system (PI-RADS ≥3) vs. ADC values in the diagnosis of Gleason score ≥7 was evaluated. Receiver operating characteristics (ROC) curve analysis gave back an ADC threshold of 0.747×10-3 mm2/s to separate between Gleason Score 6 and ≥7. The diagnostic accuracy of ADC value (cut-off 0.747×10-3 mm2/s) vs. PI-RADS score ≥3 in diagnosing PCa with Gleason score ≥7 was equal to 84% vs. 63.6% with an area under the curve (AUC) ROC of 0.81 vs. 0.71, respectively. ADC evaluation could support clinicians in decision making of patients with PI-RADS score <3 at risk for PCa.

Hyperpolarized 3He and 129Xe magnetic resonance imaging apparent diffusion coefficients: physiological relevance in older never- and ex-smokers.

Noble gas pulmonary magnetic resonance imaging (MRI) is transitioning away from 3He to 129Xe gas, but the physiological/clinical relevance of 129Xe apparent diffusion coefficient (ADC) parenchyma measurements is not well understood. Therefore, our objective was to generate 129Xe MRI ADC for comparison with 3He ADC and with well‐established measurements of alveolar structure and function in older never‐smokers and ex‐smokers with chronic obstructive pulmonary disease (COPD). In four never‐smokers and 10 COPD ex‐smokers, 3He (b = 1.6 sec/cm2) and 129Xe (b = 12, 20, and 30 sec/cm2) ADC, computed tomography (CT) density‐threshold measurements, and the diffusing capacity for carbon monoxide (DLCO) were measured. To understand regional differences, the anterior–posterior (APG) and superior–inferior (∆SI) ADC differences were evaluated. Compared to never‐smokers, COPD ex‐smokers showed greater 3He ADC (P = 0.006), 129Xe ADCb12 (P = 0.006), and ADCb20 (P = 0.006), but not for ADCb30 (P > 0.05). Never‐smokers and COPD ex‐smokers had significantly different APG for 3He ADC (P = 0.02), 129Xe ADCb12 (P = 0.006), and ADCb20 (P = 0.01), but not for ADCb30 (P > 0.05). ∆SI for never‐ and ex‐smokers was significantly different for 3He ADC (P = 0.046), but not for 129Xe ADC (P > 0.05). There were strong correlations for DLCO with 3He ADC and 129Xe ADCb12 (both r = −0.95, P < 0.05); in a multivariate model 129Xe ADCb12 was the only significant predictor of DLCO (P = 0.049). For COPD ex‐smokers, CT relative area <−950 HU (RA950) correlated with 3He ADC (r = 0.90, P = 0.008) and 129Xe ADCb12 (r = 0.85, P = 0.03). In conclusion, while 129Xe ADCb30 may be appropriate for evaluating subclinical or mild emphysema, in this small group of never‐smokers and ex‐smokers with moderate‐to‐severe emphysema, 129Xe ADCb12 provided a physiologically appropriate estimate of gas exchange abnormalities and alveolar microstructure.

Computed Tomography Density Histogram Analysis to Evaluate Pulmonary Emphysema in Ex-smokers

High-resolution computed tomography (CT) measurements of emphysema typically use Hounsfield unit (HU) density histogram thresholds or observer scores based on regions of low x-ray attenuation. Our objective was to develop an automated measurement of emphysema using principal component analysis (PCA) of the CT density histogram. Ninety-seven ex-smokers, including 53 subjects with chronic obstructive pulmonary disease (COPD) and 44 asymptomatic subjects (AEs), provided written informed consent to imaging as well as plethysmography and spirometry. We applied PCA to the CT density histogram to generate whole lung and regional density histogram principal components including the first and second components and the sum of both principal components (density histogram principal component score [DHPCS]). Significant relationships for DHPCS with single HU thresholds, pulmonary function measurements, an expert's emphysema score, and hyperpolarized (3)He magnetic resonance imaging apparent diffusion coefficients (ADCs) were determined using linear regression and Pearson coefficients. Receiver operator characteristics analysis was performed using forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC) as the independent diagnostic. There was a significant difference (P < .0001) between AE and COPD subjects for DHPCS; FEV1/FVC; diffusing capacity of lung for carbon monoxide%predicted; attenuation values below -950, -910, and -856 HU; and (3)He ADCs. There were significant correlations for DHPCS with FEV1/FVC (r = -0.85, P < .0001); diffusing capacity of lung for carbon monoxide%predicted (r = -0.67, P < .0001); attenuation values below -950/-910/-856 HU (r = 0.93/0.96/0.76, P < .0001); and (3)He ADCs (r = 0.85, P < .0001). Receiver operator characteristics analysis showed a 91% classification rate for DHPCS. We generated an automated emphysema score using PCA of the CT density histogram with a 91% COPD classification rate that showed strong and significant correlations with pulmonary function tests, single HU thresholds, and (3)He magnetic resonance imaging ADCs.

Early Response of Hepatic Malignancies to Locoregional Therapy-Value of Diffusion-Weighted Magnetic Resonance Imaging and Proton Magnetic Resonance Spectroscopy

The objective of our study was to determine the usefulness of the diffusion-weighted magnetic resonance imaging and proton magnetic resonance spectroscopy (H-MRS) of hepatic malignancies for the assessment of response to locoregional treatment. Forty-four patients (29 men; mean age, 58 years) with hepatic malignancies were treated locally. Magnetic resonance imaging examinations obtained before and at 1 and 6 months after transarterial chemoembolization were analyzed retrospectively. Imaging criteria included change in tumor size, percentage of enhancement in the arterial and portal venous phases, diffusion-weighted magnetic resonance imaging apparent diffusion coefficients, and choline concentration by quantitative H-MRS. Response to treatment was grouped according to RECIST (Response Evaluation Criteria in Solid Tumors) and European Association for the Study of the Liver (EASL) criteria based on magnetic resonance imaging at 6 months after treatment. Statistical analysis used paired t test, Fisher exact test, and univariate and multivariate Cox proportional hazards models. Before treatment, the median tumor diameter was 6 cm; at 6 months after treatment, median tumor diameter was 5.1 cm. According to RECIST and EASL, 66% of the patients achieved partial response, 31% had stable disease, and 3% of the patients showed progressive disease. One month after transarterial chemoembolization, apparent diffusion coefficient increased (P < 0.14), and mean choline concentration of the tumors decreased (P < 0.008). Diffusion-weighted imaging and hepatic choline levels by H-MRS could predict response to locoregional therapy.

Mapping and quantifying hyperpolarized 3He magnetic resonance imaging apparent diffusion coefficient gradients

We measured hyperpolarized 3He magnetic resonance imaging (MRI) apparent diffusion coefficients (ADC) and quantified ADC gradients in each three-by-three voxel region of interest (ROI). Such local ADC gradients can be represented in vector maps showing the magnitude (|G3x3|) and direction of ADC gradients, providing a qualitative visualization tool and quantitative measurement of airway and air space heterogeneity. Twenty-four subjects (15 male, mean age=67+/-7 yr) with global initiative for chronic obstructive lung disease (GOLD) stage II (n=9, mean age 68+/-6 yr), GOLD stage III chronic obstructive pulmonary disease (COPD; n=7, mean age 67+/-8 yr), and age-matched healthy volunteers (n=8, mean age 67+/-6 yr) were enrolled based on their age and spirometry results. Hyperpolarized 3He MRI was performed on a whole body 3.0 Tesla system. Mean 3He ADC and ADC standard deviation were calculated for the center coronal slice, and the mean magnitude and direction of the ADC gradient vectors were calculated for each three-by-three voxel matrix (|G3x3|). While the 3He ADC standard deviation was not significantly different, mean |G3x3| was significantly different between subjects with stage II (0.14+/-0.03 cm/s) and stage III COPD (0.19+/-0.03 cm/s; P<0.005) and between healthy subjects (0.12+/-0.03 cm/s) and those with stage II COPD (P<0.02). The second order statistic |G3x3| may provide a sensitive measure of ADC heterogeneity for ROI representing 9.4x9.4x30 mm or 2.6 cm3 of lung tissue.