B-value Diffusion-weighted Magnetic Resonance Imaging Research Articles

A Prospective Observational Study of Diagnostic Reliability of Semiquantitative and Quantitative High b-Value Diffusion-Weighted MRI in Distinguishing between Benign and Malignant Lung Lesions at 3 Tesla.

Aim The aim of this study was to evaluate the usefulness of high b-value diffusion-weighted imaging (DWI) to differentiate benign and malignant lung lesions in 3 Tesla magnetic resonance imaging (MRI). Materials and Methods Thirty-one patients with lung lesions underwent a high b-value (b= 1000 s/mm 2 ) DW MRI in 3 Tesla. Thirty lesions were biopsied, followed by histopathological analysis, and one was serially followed up for 2 years. Statistical analysis was done to calculate the sensitivity, specificity, and accuracy of different DWI parameters in distinguishing benign and malignant lesions. Receiver operating characteristic (ROC) curves were used to determine the cutoff values of different parameters. Results The qualitative assessment of signal intensity on DWI based on a 5-point rank scale had a mean score of 2.71 ± 0.75 for benign and 3. 75 ± 0.60 for malignant lesions. With a cutoff of 3.5, the sensitivity, specificity, and accuracy were 75, 86, and 77.6%, respectively. The mean ADC min (minimum apparent diffusion coefficient) value of benign and malignant lesions was 1. 49 ± 0.38 × 10-3 mm 2 /s and 1.11 ± 0.20 ×10-3 mm 2 /s, respectively. ROC curve analysis showed a cutoff value of 1.03 × 10-3 mm 2 /s; the sensitivity, specificity, and accuracy were 87.5, 71.4, and 83.3%, respectively. For lesion to spinal cord ratio and lesion to spinal cord ADC ratio with a cutoff value of 1.08 and 1.38, the sensitivity, specificity, and accuracy were 83.3 and 87.5%, 71.4 and 71.4%, and 80.6 and 83.8%, respectively. The exponential ADC showed a low accuracy rate. Conclusion The semiquantitative and quantitative parameters of high b-value DW 3 Tesla MRI can differentiate benign from malignant lesions with high accuracy and make it a reliable nonionizing modality for characterizing lung lesions.

An unsupervised convolutional neural network method for estimation of intravoxel incoherent motion parameters

Objective. Intravoxel incoherent motion (IVIM) imaging obtained by fitting a biexponential model to multiple b-value diffusion-weighted magnetic resonance imaging (DW-MRI) has been shown to be a promising tool for different clinical applications. Recently, several deep neural network (DNN) methods were proposed to generate IVIM imaging. Approach. In this study, we proposed an unsupervised convolutional neural network (CNN) method for estimation of IVIM parameters. We used both simulated and real abdominal DW-MRI data to evaluate the performance of the proposed CNN-based method, and compared the results with those obtained from a non-linear least-squares fit (TRR, trust-region reflective algorithm) and a feed-forward backward-propagation DNN-based method. Main results. The simulation results showed that both the DNN- and CNN-based methods had lower coefficients of variation than the TRR method, but the CNN-based method provided more accurate parameter estimates. The results obtained from real DW-MRI data showed that the TRR method produced many biased IVIM parameter estimates that hit the upper and lower parameter bounds. In contrast, both the DNN- and CNN-based methods yielded less biased IVIM parameter estimates. Overall, the perfusion fraction and diffusion coefficient obtained from the DNN- and CNN-based methods were close to literature values. However, compared with the CNN-based method, both the TRR and DNN-based methods tended to yield increased pseudodiffusion coefficients (55%–180%). Significance. Our preliminary results suggest that it is feasible to estimate IVIM parameters using CNN.

A Phase 2 Study of Dose-intensified Chemoradiation Using Biologically Based Target Volume Definition in Patients With Newly Diagnosed Glioblastoma

We hypothesized that dose-intensified chemoradiation therapy targeting adversely prognostic hypercellular (TVHCV) and hyperperfused (TVCBV) tumor volumes would improve outcomes in patients with glioblastoma. This single-arm, phase 2 trial enrolled adult patients with newly diagnosed glioblastoma. Patients with a TVHCV/TVCBV >1 cm3, identified using high b-value diffusion-weighted magnetic resonance imaging (MRI) and dynamic contrast-enhanced perfusion MRI, were treated over 30 fractions to 75 Gy to the TVHCV/TVCBV with temozolomide. The primary objective was to estimate improvement in 12-month overall survival (OS) versus historical control. Secondary objectives included evaluating the effect of 3-month TVHCV/TVCBV reduction on OS using Cox proportional-hazard regression and characterizing coverage (95% isodose line) of metabolic tumor volumes identified using correlative 11C-methionine positron emission tomography. Clinically meaningful change was assessed for quality of life by the European Organisation for the Research and Treatment of Cancer Quality of Life Questionnaire C30, for symptom burden by the MD Anderson Symptom Inventory for brain tumor, and for neurocognitive function (NCF) by the Controlled Oral Word Association Test, the Trail Making Test, parts A and B, and the Hopkins Verbal Learning Test-Revised. Between 2016 and 2018, 26 patients were enrolled. Initial patients were boosted to TVHCV alone, and 13 patients were boosted to both TVHCV/TVCBV. Gross or subtotal resection was performed in 87% of patients; 22% were O6-methylguanine-DNA methyltransferase (MGMT) methylated. With 26-month follow-up (95% CI, 19-not reached), the 12-month OS rate among patients boosted to the combined TVHCV/TVCBV was 92% (95% CI, 78%-100%; P = .03) and the median OS was 20 months (95% CI, 18-not reached); the median OS for the whole study cohort was 20 months (95% CI, 14-29 months). Patients whose 3-month TVHCV/TVCBV decreased to less than the median volume (3 cm3) had superior OS (29 vs 12 months; P = .02). Only 5 patients had central or in-field failures, and 93% (interquartile range, 59%-100%) of the 11C-methionine metabolic tumor volumes received high-dose coverage. Late grade 3 neurologic toxicity occurred in 2 patients. Among non-progressing patients, 1-month and 7-month deterioration in quality of life, symptoms, and NCF were similar in incidence to standard therapy. Dose intensification against hypercellular/hyperperfused tumor regions in glioblastoma yields promising OS with favorable outcomes for NCF, symptom burden, and quality of life, particularly among patients with greater tumor reduction 3 months after radiation therapy.

Can anomalous diffusion models in magnetic resonance imaging be used to characterise white matter tissue microstructure?

PurposeDuring the time window of diffusion weighted magnetic resonance imaging experiments (DW-MRI), water diffusion in tissue appears to be anomalous as a transient effect, with a mean squared displacement that is not a linear function of time. A number of statistical models have been proposed to describe water diffusion in tissue, and parameters describing anomalous as well as Gaussian diffusion have previously been related to measures of tissue microstructure such as mean axon radius. We analysed the relationship between white matter tissue characteristics and parameters of existing statistical diffusion models. MethodsA white matter tissue model (ActiveAx) was used to generate multiple b-value diffusion-weighted magnetic resonance imaging signals. The following models were evaluated to fit the diffusion signal: 1) Gaussian models - 1a) mono-exponential decay and 1b) bi-exponential decay; 2) Anomalous diffusion models - 2a) stretched exponential, 2b) continuous time random walk and 2c) space fractional Bloch-Torrey equation. We identified the best candidate model based on the relationship between the diffusion-derived parameters and mean axon radius and axial diffusivity, and applied it to the in vivo DW-MRI data acquired at 7.0 T from five healthy participants to estimate the same selected tissue characteristics. Differences between simulation parameters and fitted parameters were used to assess accuracy and in vivo findings were compared to previously reported observations. ResultsThe space fractional Bloch-Torrey model was found to be the best candidate in characterising white matter on the base of the ActiveAx simulated DW-MRI data. Moreover, parameters of the space fractional Bloch-Torrey model were sensitive to mean axon radius and axial diffusivity and exhibited low noise sensitivity based on simulations. We also found spatial variations in the model parameter β to reflect changes in mean axon radius across the mid-sagittal plane of the corpus callosum. ConclusionSimulations have been used to define how the parameters of the most common statistical magnetic resonance imaging diffusion models relate to axon radius and diffusivity. The space fractional Bloch-Torrey equation was identified as the best model for the characterisation of axon radius and diffusivity. This model allows changes in mean axon radius and diffusivity to be inferred from spatially resolved maps of model parameters.

Predicting Prostate Biopsy Outcomes: A Preliminary Investigation on Screening with Ultrahigh B-Value Diffusion-Weighted Imaging as an Innovative Diagnostic Biomarker.

BackgroundRoutine screening of prostate specific antigen (PSA) is no longer recommended because of a high rate of over-diagnosis of prostate cancer (PCa).ObjectiveTo evaluate the efficacy of diffusion-weighted magnetic resonance imaging (DW-MRI) for PCa detection, and to explore the clinical utility of ultrahigh b-value DW-MRI in predicting prostate biopsy outcomes.Methodology73 male patients were selected for the study. They underwent 3T MRI using T2WI conventional DW-MRI with b-value 1000 s/mm2, and ultrahigh b-value DW-MRI with b-values of 2000 s/mm2 and 3000 s/mm2. Two radiologists evaluated individual prostate gland images on a 5-point rating scale using PI-RADS, for the purpose of region-specific comparisons among modalities. Sensitivity, specificity, accuracy, positive predictive value (PPV), negative predictive value (NPV) and likelihood ratios (LR) were investigated for each MRI modality. The area under the receiver operating characteristic (ROC) curve (AUC) was also calculated.ResultsResults showed the improved diagnostic value of ultrahigh b-value DWI-MRI for detection of PCa when compared to other b values and conventional MRI protocols. Sensitivity values for 3000 s/mm2 in both peripheral zone (PZ) and transition zone (TZ) were significantly higher than those observed with conventional DW-MRI—Specificity values for 3000 s/mm2 in the TZ were significantly higher than other b-value images, whereas specificity values using 3000 s/mm2 in the PZ were not significantly higher than 2000 s/mm2 images. PPV and NPV between 3000 s/mm2 and the other three modalities were significantly higher for both PZ and TZ images. The PLRs and NLRs of b-value 3000 s/mm2 DW-MRI in the PZ and TZ were also recorded. ROC analysis showed greater AUCs for the b value 3000 s/mm2 DWI than for the other three modalities.ConclusionsDW-MRI with a b-value of 3000 s/mm2 was found to be the most accurate and reliable MRI modality for PCa tumor detection and localization, particularly for TZ lesion discrimination. It may be stated that the b-value of 3000 s/mm2 is a novel, improved diagnostic biomarker with greater predictive accuracy for PCa prior to biopsy.

Correlation Between Apparent Diffusion Coefficients and Standardized Uptake Values in Hybrid (18)F-FDG PET/MR: Preliminary Results in Rectal Cancer.

PurposeFluorine-18-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) and diffusion-weighted magnetic resonance imaging (DWI) share the same role in clinical oncology and it is feasible to obtain the standardized uptake value (SUV) and apparent diffusion coefficient (ADC) simultaneously by emerging the hybrid positron emission tomography/magnetic resonance (PET/MR). This study investigated the correlation between the ADCs of rectal cancer lesions and their SUVs derived from hybrid PET/MR.MethodsNine patients with histologically proven rectal adenocarcinoma (5 men, 4 women; mean age, 70 ± 15.91 years) underwent torso 18F-FDG PET/CT and regional hybrid 18F-FDG PET/MR sequentially. A fixed threshold value of 40 % of maximum uptake was used to determine tumor volume of interest (VOI) on PET image; SUVmax, SUVpeak, and SUVmean were calculated automatically. A single freehand region of interest (ROI) was drawn on high b-value (b1000) DWI image and copied to corresponding ADC map to determine the ADCmean of rectal cancer lesion. Spearman’s rank correlation coefficient (ρ) was calculated to determine the correlation between SUVs and ADC values.ResultsSUVmax, SUVpeak, and SUVmean derived by hybrid PET/MR were 12.35 ± 4.66 (mean ± standard deviation), 9.66 ± 3.15 and 7.41 ± 2.54, respectively. The ADCmean value of rectal cancer lesions was 1.02 ± 0.08 × 10−3mm2/s. ADCmean was significantly and inversely correlated with SUV values (SUVmax, ρ = −0.95, p < 0.001; SUVpeak, ρ = −0.93, p < 0.001; SUVmean, ρ = −0.91, p = 0.001).ConclusionsThis preliminary hybrid PET/MR study demonstrates a significant inverse correlation exists between metabolic activity on 18F-FDG PET and water diffusion on DWI in rectal cancer.

Standard b-value versus low b-value diffusion-weighted MRI in renal cell carcinoma: a systematic review and meta-analysis.

BackgroundWe sought to determine the comparative diagnostic performance of standard b-value (800–1000 s/mm2) versus low b-value (400–500 s/mm2) diffusion-weighted magnetic resonance imaging (DW-MRI) in the detection of renal cell carcinoma (RCC).MethodAfter a systematic review of the available literature, studies were included that reported b-values, used a histopathological reference standard, and allowed construction of 2 × 2 contingency tables for detection of RCC lesions using DW-MRI. In addition, a summary receiver operating characteristic (SROC) analysis was performed.ResultsFour articles that complied with all inclusion and exclusion criteria were selected for data extraction and analysis (n = 248 lesions in 266 patients). All four studies were high quality. Standard b-value DW-MRI displayed a pooled sensitivity of 0.59 (95% confidence interval (CI): 0.51-0.67) and a pooled specificity of 0.50 (95% CI: 0.30-0.70), while low b-value DW-MRI displayed a pooled sensitivity of 0.58 (95% CI: 0.48-0.63) and a pooled specificity of 0.23 (95% CI: 0.09-0.44). The SROC curve of standard b-value DW-MRI displayed an AUC of 0.61 and a Q*index of 0.59, while the SROC curve of low b-value DW-MRI displayed an AUC of 0.68 and a Q*index of 0.64.ConclusionStandard b-value DW-MRI showed a superior specificity but an approximately equivalent sensitivity to low b-value DW-MRI in detecting RCC lesions in the kidney. However, low b-value DW-MRI displayed an overall superior diagnostic accuracy over standard b-value DW-MRI.

Diffusion-weighted magnetic resonance imaging for evaluating the histological degree of malignancy in patients with intraductal papillary mucinous neoplasm.

The aim of this study was to evaluate the usefulness of high b-value diffusion-weighted magnetic resonance imaging (DWI) for evaluating the histological degree of malignancy in patients with intraductal papillary mucinous neoplasm (IPMN). A total of 35 patients (mean age 68 ± 10 years, 23 males) who had undergone DWI before surgery were included in this study. Of these 35 patients, 13 had IPMN with low- or intermediate-grade dysplasia, eight had IPMN with high-grade dysplasia, and 14 had IPMN with an associated invasive carcinoma. We evaluated the positive signal rate on DWI and the apparent diffusion coefficient (ADC) value of each pathology. The positive signal rate on DWI of IPMN with low- or intermediate-grade dysplasia, of IPMN with high-grade dysplasia, and of IPMN with an associated invasive carcinoma were 0% (0/13), 38% (3/8), and 93% (13/14), respectively. The sensitivity, specificity, and accuracy for malignancy (IPMN with high-grade dysplasia or IPMN with an associated invasive carcinoma) using DWI were 73%, 100%, and 83%, respectively. The mean ADC value of malignancy was significantly lower than that of benignity (P = 0.002). Diffusion-weighted magnetic resonance imaging, easily applicable in addition to conventional MRI, is considered an efficient modality for evaluating the histological degree of malignancy in patients with IPMN.

Ultra-high b-value diffusion-weighted MRI for the detection of prostate cancer with 3-T MRI

To determine, with histopathological findings of radical prostatectomy as reference, whether diffusion-weighted imaging (DWI) using b = 2000 s/mm(2) for 3-T magnetic resonance imaging (MRI) is superior to the use of b = 1000 s/mm(2) for prostate cancer detection. This study evaluated 73 patients with biopsy-proven prostate cancer. All patients underwent preoperative 3-T MRI using T2-weighted imaging (T2WI) and DWI (b = 0, 1000, 2000 s/mm(2) ). The following three sets of images were evaluated separately by two radiologists: protocol A (T2WI alone), protocol B (T2WI and DWI with b = 1000 s/mm(2) ), and protocol C (T2WI and DWI with b = 2000 s/mm(2) ). For estimation of diagnostic capability, area under the receiver operating characteristic (ROC) curve (AUC) was calculated. A total of 341 cancer foci were found in the prostectomy specimens of 73 patients. Reader 1 rated AUCs of the three sets as; A 0.66, B 0.77, C 0.80. ROC analysis showed significant differences among the three protocols (A vs. B vs. C: P < 0.0001, A vs. B: P < 0.0001, B vs. C: P < 0.0001). The use of b = 2000 s/mm(2) for DWI with 3-T MRI is diagnostically superior to that of b = 1000 s/mm(2) for prostate cancer detection.

High b-value diffusion-weighted magnetic resonance imaging for gallbladder lesions: differentiation between benignity and malignancy

Recently, the clinical application of diffusion-weighted magnetic resonance imaging (DWI) has been expanding to abdominal organs. However, only a few studies on gallbladder diseases have been published. The aim of this study was to evaluate the usefulness and limitations of high b-value DWI for gallbladder diseases. A total of 153 patients (mean age 60 ± 15 years, 78 males) who had undergone DWI for evaluating gallbladder wall thickening or polypoid lesions were included in this study. Of these 153 patients, 36 had gallbladder cancer and 117 had benign gallbladder diseases (67 chronic cholecystitis, 44 adenomyomatosis, four cholesterol polyp, one gallbladder adenoma, and one xanthogranulomatous cholecystitis). We evaluated the positive signal rate with DWI and the apparent diffusion coefficient (ADC) value of each disease. The positive signal rate with DWI was significantly higher in gallbladder cancer (78 %) than in benign gallbladder diseases (22 %) (p < 0.001). The mean ADC value of gallbladder cancer was (1.83 ± 0.69) × 10(-3) mm(2)/s and that of benign gallbladder diseases was (2.60 ± 0.54) × 10(-3) mm(2)/s (p < 0.001). Benign gallbladder diseases with acute cholecystitis or a history of that had a higher positive signal rate with DWI (p < 0.001) and a lower ADC value (p = 0.018) than those without such conditions. DWI can contribute to the improvement of the diagnostic capability for gallbladder wall thickening or polypoid lesions by compensating for weaknesses of other modalities by its many advantages, although cases with acute cholecystitis or such history sometimes show false-positive on DWI.

Lymphomas and glioblastomas: Differences in the apparent diffusion coefficient evaluated with high b-value diffusion-weighted magnetic resonance imaging at 3 T

As the usefulness of the apparent diffusion coefficient (ADC) obtained from diffusion-weighted images (DWI) for the differential diagnosis between glioblastoma and primary central nervous system lymphoma is controversial, we assessed whether high b-value DWI at b 4000 s/mm(2) could discriminate between glioblastoma and lymphoma. We also compared the power of high- and standard b-value (b-4000, b-1000) imaging on a 3-Tesla (3T) magnetic resonance (MR) instrument. This study was approved by our Institutional Review Board. We acquired DWI at 3T with b = 1000 and b = 4000 s/mm(2) in 10 patients with lymphoma and 14 patients with glioblastoma. The ADC was measured by placing multiple regions of interest (ROI) on ADC maps of the site of enhanced lesions on contrast-enhanced T1-weighted MR images. We avoided hemorrhagic and cystic lesions by using T1-, T2-, FLAIR-, and T2* MR images. The ADC values of each tumor were determined preoperatively from several ROI and expressed as the minimum-, mean-, and maximum ADC value (ADC(MIN), ADC(MEAN), ADC(MAX)). We evaluated the relationship between ADCs and histological information including tumor cellularity. All ADC values were statistically associated with tumor cellularity. ADC(MIN) at b-4000 was associated with tumor cellularity more significantly than ADC(MIN) at b-1000. All ADC values were lower for lymphoma than glioblastoma and the statistical difference was larger at b = 4000- than b = 1000 s/mm(2). According to the results of discriminant analysis, the log likelihood was greatest for ADC(MIN) at b = 4000. At a cut-off value of ADC(MIN) = 0.500 × 10(-3)mm(2)/s at b-4000 it was possible to differentiate between lymphoma and glioblastoma (sensitivity 90.9%, specificity 91.7%). Calculating the ADC value is useful for distinguishing lymphoma from glioblastoma. The lowest degree of overlapping and a better inverse correspondence with tumor cellularity were obtained with ADC(MIN) at b-4000 s/mm(2) at 3T MRI.

Diffusion-weighted magnetic resonance imaging of urinary epithelial cancer with upper urinary tract obstruction: preliminary results

Various malignant tumors of the body show high signal intensity on diffusion-weighted magnetic resonance imaging (DWI). In the genitourinary region, DWI is expected to have a role in detecting urinary epithelial cancer noninvasively. To demonstrate the feasibility of DWI for the diagnosis of urinary epithelial cancer with upper urinary tract obstruction. Twenty upper urinary tract cancers in 16 patients were evaluated by high-b-value DWI (b=800 s/mm(2)). The signal intensity was visually evaluated, and the apparent diffusion coefficients (ADCs) were measured. All urinary epithelial cancers showed high signal intensity on DWI. The ADC in cancerous lesions was 1.31+/-0.27 x 10(-3) mm(2)/s, which was significantly lower than that of the lumens of the ureter or renal pelvis (3.32+/-0.44 x 10(-3) mm(2)/s; P<0.001). Maximum intensity projection images of DWI in combination with static-fluid MR urography provided three-dimensional entire urinary tract imaging with the extension of tumors. DWI is useful in the tumor detection and in evaluating the tumor extension of urinary epithelial cancer in patients with upper urinary tract obstruction.

High-b-value diffusion-weighted magnetic resonance imaging of pancreatic cancer and mass-forming chronic pancreatitis: preliminary results

Mass-forming chronic pancreatitis may mimic a pancreatic cancer on dynamic computed tomography (CT) and magnetic resonance (MR) imaging, and preoperative differential diagnosis is often difficult. Recently, the usefulness of diffusion-weighted MR imaging (DWI) in the diagnosis of pancreatic cancer has been reported in several studies. To determine whether high-b-value DWI can distinguish pancreatic cancer from benign mass-forming chronic pancreatitis. Twenty pancreatic cancers and four cases of mass-forming chronic pancreatitis were evaluated by high-b-value DWI (b=800 s/mm(2)). The signal intensity on DWI was visually evaluated, and the isotropic apparent diffusion coefficients (ADCs) were measured. All twenty pancreatic cancers showed high signal intensity (18 showed very high, two showed slightly high) on DWI. None of the mass-forming chronic pancreatitis cases showed very high intensity (three showed iso to low, one showed slightly high) on DWI. The ADCs in the pancreatic cancer and mass-forming chronic pancreatitis were 1.38 +/- 0.32 x 10(-3) mm(2)/s and 1.00 +/- 0.18 x 10(-3) mm(2)/s, respectively (P < 0.05). On high-b-value DWI, most pancreatic cancers showed very high signal intensity, and may hence be distinguished from benign mass-forming chronic pancreatitis based on our preliminary results.

Early detection of response to radiation therapy in patients with brain malignancies using conventional and high b-value diffusion-weighted magnetic resonance imaging.

To study the feasibility of using diffusion-weighted magnetic resonance imaging (DWMRI), which is sensitive to the diffusion of water molecules in tissues, for detection of early tumor response to radiation therapy; and to evaluate the additional information obtained from high DWMRI, which is more sensitive to low-mobility water molecules (such as intracellular or bound water), in increasing the sensitivity to response. Standard MRI and DWMRI were acquired before and at regular intervals after initiating radiation therapy for 10 malignant brain lesions in eight patients. One week posttherapy, three of six responding lesions showed an increase in the conventional DWMRI parameters. Another three responding lesions showed no change. Four nonresponding lesions showed a decrease or no change. The early change in the diffusion parameters was enhanced by using high DWMRI. When high DWMRI was used, all responding lesions showed increase in the diffusion parameter and all nonresponding lesions showed no change or decrease. Response was determined by standard MRI 7 weeks posttherapy. The changes in the diffusion parameters measured 1 week after initiating treatment were correlated with later tumor response or no response (P <.006). This correlation was increased to P <.0006 when high DWMRI was used. The significant correlation between changes in diffusion parameters 1 week after initiating treatment and later tumor response or no response suggests the feasibility of using DWMRI for early, noninvasive prediction of tumor response. The ability to predict response may enable early termination of treatment in nonresponding patients, prevent additional toxicity, and allow for early changes in treatment.