Magnetic Resonance Q Mapping Reveals a Decrease in Microvessel Density in the arcAβ Mouse Model of Cerebral Amyloidosis

Dynamic Contrast-Enhanced Magnetic Resonance Imaging for Localization of Recurrent Prostate Cancer After External Beam Radiotherapy

BackgroundRadiation-induced parotid damage is one of the most common complications in patients with nasopharyngeal carcinoma (NPC) undergoing radiotherapy (RT). Intravoxel incoherent motion (IVIM) magnetic resonance (MR) imaging has been reported for evaluating irradiated parotid damage. However, the changes of IVIM perfusion-related parameters in irradiated parotid glands have not been confirmed by conventional perfusion measurements obtained from dynamic contrast-enhanced (DCE) MR imaging. The purposes of this study were to monitor radiation-induced parotid damage using IVIM and DCE MR imaging and to investigate the correlations between changes of these MR parameters.MethodsEighteen NPC patients underwent bilateral parotid T1-weighted, IVIM and DCE MR imaging pre-RT (2 weeks before RT) and post-RT (4 weeks after RT). Parotid volume; IVIM MR parameters, including apparent diffusion coefficient (ADC), pure diffusion coefficient (D), pseudo-diffusion coefficient (D*), and perfusion fraction (f); and DCE MR parameters, including maximum relative enhancement (MRE), time to peak (TTP), Wash in Rate, and the degree of xerostomia were recorded. Correlations of parotid MR parameters with mean radiation dose, atrophy rate and xerostomia degree, as well as the relationships between IVIM and DCE MR parameters, were investigated.ResultsFrom pre-RT to post-RT, all of the IVIM and DCE MR parameters increased significantly (p < 0.001 for ADC, D, f, MRE, Wash in Rate; p = 0.024 for D*; p = 0.037 for TTP). Change rates of ADC, f and MRE were negatively correlated with atrophy rate significantly (all p < 0.05). Significant correlations were observed between the change rates of D* and MRE (r = 0.371, p = 0.026) and between the change rates of D* and TTP (r = 0.396, p = 0.017). The intra- and interobserver reproducibility of IVIM and DCE MR parameters was good to excellent (intraclass correlation coefficient, 0.633–0.983).ConclusionsEarly radiation-induced changes of parotid glands could be evaluated by IVIM and DCE MR imaging. Certain IVIM and DCE MR parameters were correlated significantly.

To investigate the value of in vivo proton (H) magnetic resonance spectroscopy (MRS) in longitudinally monitoring the treatment response of malignant musculoskeletal tumors under chemotherapy. Twenty-three studies in 3 patients with bone and soft-tissue tumors (2 lymphomas and 1 alveolar soft part sarcoma) were included in the study. The dynamic contrast-enhanced magnetic resonance (MR) imaging and single-voxel proton MRS with 135 milliseconds of echo time were carried out using a whole-body 1.5-T scanner and a surface coil. The volume of interest within the lesion was positioned on the area of early enhancement according to the finding of the first dynamic contrast-enhanced MR imaging with subtraction. The choline and water intensities were measured at the peak areas at 3.2 and 4.5 ppm. The choline-water ratios were calculated as well. Statistical analysis was performed by using Kruskal-Wallis 1-way analysis of variance test ().(Table is included in full-text article.) The changes observed on the dynamic contrast-enhanced MR images and tumor size after chemotherapy fell into 2 clearly distinct patterns: subsequent partial response (patients 1 and 2) and progressive disease (patient 3). The choline concentration, choline-volume ratio, and choline-water ratio in the first 2 patients were reduced substantially to zero in the follow-up MRS. In the remaining patient, the choline, choline-volume ratio, and choline-water ratio remained high in the follow-up MRS. The water concentration and water-volume ratio between the 3 patients showed significant statistical differences (Kruskal-Wallis test, P = 0.004 and 0.039). In vivo proton MRS is technically feasible for the evaluation of musculoskeletal tumors. Choline can be detected in malignant bone and soft-tissue tumors, and the early metabolite changes after chemotherapy can also be identified in the in vivo proton MRS by using a standard clinical-use 1.5-T MR scanner and a surface coil. The decline of choline after treatment in malignant bone and soft-tissue tumors correlates with the response of the dynamic contrast MR images and the tumor size. The information provided with MR imaging and proton MRS may improve the diagnostic specificity of MR examination in the follow-up of tumor treatment.

In this study, we quantified perfusion deficits using dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) with an extravasating contrast agent (CA). We also investigated the efficacy of leakage compensation from CA pre-load in brains from post-ischemic rat models without significant dynamic contrast-enhanced MRI (DCE-MRI)-derived vessel wall permeability. DSC measurements were obtained using fast (0.3 s) echo-planar imaging in both normal rats and rats with transient middle carotid artery occlusion (MCAO) (1-h MCAO, 24-h reperfusion) after successive administrations of gadoterate meglumine (Dotarem) and intravascular superparamagnetic iron oxide nanoparticles (SPION). The relative cerebral blood volume (CBV) and cerebral blood flow (CBF) values acquired using Dotarem were significantly underestimated (~20%) when compared to those acquired using SPION in ipsilesional post-ischemic brain regions. A slight overestimation of relative mean transit time was observed. Areas with underestimated CBV and CBF values from the corresponding error maps encompassed the area of infarcted tissue (apparent diffusion coefficient < 500 μm2/s) and mostly coincided with the area wherein conspicuous longitudinal relaxation time differences were observed pre- vs. post-injection of Dotarem. The DSC measurements with significant pre-load (0.3 mmol·kg-1) of Dotarem displayed minimal perfusion deficits when compared to those determined using the reference intravascular SPION.

Validation of Fourier decomposition MRI with dynamic contrast-enhanced MRI using visual and automated scoring of pulmonary perfusion in young cystic fibrosis patients

Multivariate pattern analysis is often assumed to rely on signals that directly reflect differences in the distribution of particular neural populations. The source of the signal used in these analyses remains unclear however, and an alternative model suggests that signal from larger draining veins may play a significant role. The current study was designed to investigate the vascular contribution to pattern analyses at 3T by comparing the results obtained from gradient and spin echo data. Classification analyses were carried out comparing line orientations in V1, tone frequencies in A1, and responses from different fingers in M1. In all cases, classification accuracy in the spin echo data was not significantly different from chance. In contrast, classification accuracies in the gradient echo data were significantly above chance, and significantly higher than the accuracies observed for the spin echo data. These results suggest that at the field strength and spatial resolution used for the majority of fMRI studies, a considerable proportion of the signal used by pattern analysis originates in the vasculature.

Simple SummaryWhole-body magnetic resonance imaging (MRI) is recognized as the most sensitive imaging technique for the detection of bone marrow infiltration, and was therefore, recently included in the new diagnostic myeloma criteria, as proposed by the International Myeloma Working Group. The use of diffusion-weighted MRI further improved the performances of whole-body MRI in the setting of multiple myeloma, and its systematic implementation in general clinical practice is now recommended. Whole-body, dynamic, contrast-enhanced MRI might provide further information on lesions vascularity and might help evaluate response to treatment. Hybrid PET/MRI might act as the optimal imaging modality, owing to the association of the best techniques for both detecting bone marrow involvement and evaluating treatment response, providing one-stop-shop imaging in a whole-body scale. This review provides an overview on the value of whole-body MRI, including diffusion-weighted and dynamic contrast-enhanced MRI and whole-body 18F-FDG PET/MRI in diagnosis, staging, and response evaluation in multiple myeloma.Bone disease is one of the major features of multiple myeloma (MM), and imaging has a pivotal role in both diagnosis and follow-up. Whole-body magnetic resonance imaging (MRI) is recognized as the gold standard for the detection of bone marrow involvement, owing to its high sensitivity. The use of functional MRI sequences further improved the performances of whole-body MRI in the setting of MM. Whole-body diffusion-weighted (DW) MRI is the most attractive functional technique and its systematic implementation in general clinical practice is now recommended by the International Myeloma Working Group. Whole-body dynamic contrast-enhanced (DCE) MRI might provide further information on lesions vascularity and help evaluate response to treatment. Whole Body PET/MRI is an emerging hybrid imaging technique that offers the opportunity to combine information on morphology, fat content of bone marrow, bone marrow cellularity and vascularization, and metabolic activity. Whole-body PET/MRI allows a one-stop-shop examination, including the most sensitive technique for detecting bone marrow involvement, and the most recognized technique for treatment response evaluation. This review aims at providing an overview on the value of whole-body MRI, including DW and DCE MRI, and combined whole-body 18F-FDG PET/MRI in diagnosis, staging, and response evaluation in patients with MM.

Given the limitations of conventional imaging in accurately grading gliomas, predicting molecular subtypes, and assessing tumor proliferation and angiogenesis, there is a growing need for advanced quantitative magnetic resonance imaging (MRI) biomarkers. This study aimed to compare the diagnostic performance of histogram features of dynamic contrast enhanced (DCE) and dynamic susceptibility contrast (DSC) imaging in predicting glioma grade and genotyping, as well as to explore the association between DCE and DSC with Ki-67 and microvascular density (MVD). Forty-six patients with gliomas were enrolled prospectively. The histogram features of DCE and DSC were extracted from the entire tumor and compared among subgroups based on the grades and status of isocitrate dehydrogenase (IDH) mutation and 1p/19q co-deletion. Pearson correlation analyses were employed to examine the associations among Ki-67, MVD, and histogram features of perfusion model. Receiver operating characteristic (ROC) analyses were used to evaluate the accuracy of DCE and DSC in differentiating glioma grades and genotypes, while Cox regression analyses identified prognostic factors associated with survival after surgical resection. A cohort of 46 patients with IDH-mutant (n=23) and IDH-wildtype (n=23) gliomas was analyzed. DCE-MRI histogram features demonstrated superior performance to DSC parameters in both IDH genotyping and tumor grading. For IDH discrimination, 90th percentile of volume fraction of the extravascular-extracellular space (Ve) [area under the curve (AUC) =0.849, sensitivity 91.3%, specificity 78.3%] and mean value of volume transfer constant (Ktrans) (AUC =0.847, sensitivity 87.0%, specificity 82.6%) showed optimal performance (both P<0.001). In contrast, DSC-derived relative cerebral blood volume (rCBV) (AUC =0.577) and relative cerebral blood flow (rCBF) (AUC =0.537) exhibited limited diagnostic value (P>0.05). In tumor grading, 90th percentile of Ve (AUC =0.923) and mean value of Ktrans (AUC =0.908) achieved near-perfect differentiation (sensitivity 83.9%, specificity 93.3%; P<0.001). While DSC-derived parameters showed improved performance compared to genotyping (rCBV: AUC =0.742, P=0.008; rCBF: AUC =0.688, P=0.040), DCE-based models remained significantly superior (DeLong's test P<0.05 for all comparisons). Significant correlations were observed between DCE parameters and both Ki-67 proliferation index (r=0.42-0.51) and MVD (r=0.35-0.56; all P<0.05). Survival analysis identified three independent prognostic factors: O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation [hazard ratio (HR) =4.15, 95% confidence interval (CI): 1.10-15.68, P=0.04], elevated Ktrans (HR =1.08, 95% CI: 1.01-1.17, P=0.03), and rCBV (HR =1.87, 95% CI: 1.17-2.97, P=0.009). The histogram features of DCE and DSC demonstrate exceptional diagnostic efficacy in glioma grading, with DCE providing deeper insights into the molecular characteristics of glioma.

Robust approaches to quantify tumor heterogeneity are needed to provide early decision support for precise individualized therapy. To conduct a technical exploration of longitudinal changes in tumor heterogeneity patterns on dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI), diffusion-weighted imaging (DWI) and FDG positron emission tomography / computed tomography (PET/CT), and their association to radiation therapy (RT) response in cervical cancer. Prospective observational study with longitudinal MRI and PET/CT pre-RT, early-RT (2 weeks), and mid-RT (5 weeks). Twenty-one FIGO IB2 -IVA cervical cancer patients receiving definitive external beam RT and brachytherapy. 1.5T, precontrast axial T1 -weighted, axial and sagittal T2 -weighted, sagittal DWI (multi-b values), sagittal DCE MRI (<10 sec temporal resolution), postcontrast axial T1 -weighted. Response assessment 1 month after completion of treatment by a board-certified radiation oncologist from manually delineated tumor volume changes. Intensity histogram (IH) quantiles (DCE SI10% and DWI ADC10% , FDG-PET SUVmax ) and distribution moments (mean, variance, skewness, kurtosis) were extracted. Differences in IH features between timepoints and modalities were evaluated by Skillings-Mack tests with Holm's correction. Area under receiver-operating characteristic curve (AUC) and Mann-Whitney testing was performed to discriminate treatment response using IH features. Tumor IH means and quantiles varied significantly during RT (SUVmean : ↓28-47%, SUVmax : ↓30-59%, SImean : ↑8-30%, SI10% : ↑8-19%, ADCmean : ↑16%, P < 0.02 for each). Among IH heterogeneity features, FDG-PET SUVCoV (↓16-30%, P = 0.011) and DW-MRI ADCskewness decreased (P = 0.001). FDG-PET SUVCoV was higher than DCE-MRI SICoV and DW-MRI ADCCoV at baseline (P < 0.001) and 2 weeks (P = 0.010). FDG-PET SUVkurtosis was lower than DCE-MRI SIkurtosis and DW-MRI ADCkurtosis at baseline (P = 0.001). Some IH features appeared to associate with favorable tumor response, including large early RT changes in DW-MRI ADCskewness (AUC = 0.86). Preliminary findings show tumor heterogeneity was variable between patients, modalities, and timepoints. Radiomic assessment of changing tumor heterogeneity has the potential to personalize treatment and power outcome prediction. 2 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2018;47:1388-1396.

To investigate the efficacy of perfusion magnetic resonance imaging (MRI) in benign-malignant differentiation of thyroid nodules. Images from 24 patients with thyroid masses were obtained using dynamic contrast enhanced MRI (DCE-MRI) at 3-T MR. DCE-MRI images were evaluated by post-processing of selected regions of interest (ROIs) on software, thus eliciting quantitative data for each voxel within the ROI. Ktrans, Ve, Kep, iAUC and chi2 were calculated automatically. The DCE-MRI values of benign and malignant lesions were then compared. Mean Ktrans and iAUC values in malignant lesions were significantly lower than those in benign lesions (p = 0.028 and 0.049). Ktrans, Kep, and iAUC values in malignant lesions were statistically significantly lower than normal parenchyma values. In contrast to other tissues, the perfusion MRI findings of thyroid masses exhibit a decrease in Ktrans and iAUC values as malignancy increases. Perfusion MRI may be useful in differentiating benign and malignant thyroid nodules once a cut-off value has been determined by other studies.

Early assessment of response to chemotherapy in lung cancer using dynamic contrast-enhanced MRI: a proof-of-concept study

To prospectively determine clinical value of dynamic contrast material-enhanced magnetic resonance (MR) imaging in the evaluation of disease activity in perianal Crohn disease (CD). Patients provided written informed consent. Study approval was waived by an institutional review board. Thirty-three patients with perianal CD underwent pelvic MR imaging; 17 were male (mean age, 37.4 years +/- 10.8 [standard deviation]; age range, 18-54 years) and 16 were female (mean age, 32.0 years +/- 8.3; age range, 16-43 years). Dynamic contrast-enhanced MR imaging was performed; time-intensity curves (TICs) were obtained. Each pixel was classified as one of six predefined TIC shape types. For each MR imaging examination, a region of interest (ROI) was drawn around the fistula on the single section corresponding to the most extensive and most hyperintense lesion; maximum enhancement (ME), slope of enhancement, and TIC shapes were calculated. Absolute and relative numbers of pixels for each curve type were calculated in a two-dimensional ROI. These results were compared with Perianal Disease Activity Index (PDAI), C-reactive protein (CRP) level, an MR imaging-based severity score, and clinical outcome. A Spearman rank correlation test was used to calculate correlation coefficients between dynamic contrast-enhanced MR imaging parameters and reference parameters. A Mann-Whitney U test was used to calculate differences in dynamic contrast-enhanced MR imaging parameters between predefined groups of patients. Significant correlations were found between the absolute amounts of the TIC shape types and PDAI and between ROI volume and PDAI. The ratio of quickly enhancing versus slowly enhancing pixels correlated with higher MR imaging scores as did the ROI volume. The absolute amounts of pixels displaying TIC types 2, 3, 4, and 5 correlated significantly with MR imaging score. CRP level showed a significant correlation with mean ME. Larger numbers of quickly enhancing pixels were observed in patients who needed medication changes or developed new abscesses during follow-up. Dynamic contrast-enhanced MR imaging can help determine disease activity in perianal CD and might be helpful in selecting a subpopulation of patients who should be monitored more closely for development of more extensive disease.

PurposeThis study aims to investigate values of intra- and peri-tumoral regions in the mammography and magnetic resonance imaging (MRI) image for prediction of sentinel lymph node metastasis (SLNM) in invasive breast cancer (BC).MethodsThis study included 208 patients with invasive BC between Spe. 2017 and Apr. 2021. All patients underwent preoperative digital mammography (DM), digital breast tomosynthesis (DBT), dynamic contrast-enhanced MRI (DCE-MRI) and diffusion-weighted MRI (DWI) scans. Radiomics features were extracted from manually outlined intratumoral regions, and automatically dilated peritumoral tumor regions in each modality. The least absolute shrinkage and selection operator (LASSO) regression was used to select key features from each region to develop radiomics signatures (RSs). Area under the receiver operating characteristic curve (AUC), accuracy, sensitivity, specificity and negative predictive value (NPV) were calculated to evaluate performance of the RSs.ResultsIntra- and peri-tumoral regions of BC can provide complementary information on the SLN status. In each modality, the Com-RSs derived from combined intra- and peri-tumoral regions always yielded higher AUCs than the Intra-RSs or Peri-RSs. A total of 10 and 11 features were identified as the most important predictors from mammography (DM plus DBT) and MRI (DCE-MRI plus DWI), respectively. The DCE-MRI plus DWI generated higher AUCs compared with DM plus DBT in the training (AUCs, DCE-MRI plus DWI vs. DM plus DBT, 0.897 vs. 0.846) and validation (AUCs, DCE-MRI plus DWI vs. DM plus DBT, 0.826 vs. 0.786) cohort.ConclusionsRadiomics features from intra- and peri-tumoral regions can provide complementary information to identify the SLNM in both mammography and MRI. The DCE-MRI plus DWI generated lower specificity, but higher AUC, accuracy, sensitivity and negative predictive value compared with DM plus DBT.

To investigate the feasibility of dynamic, contrast-enhanced, magnetic resonance imaging (DCE-MRI) for perfusion quantification of gastric cancers, and to correlate the DCE-MRI parameters with the pathological prognostic factors. This prospective study was approved by our Institutional Review Board. Twenty-seven patients with gastric cancers underwent DCE-MRI using a free-breathing, radial, gradient-echo (GRE) sequence with k-space weighted image contrast (KWIC) reconstruction on a 3T scanner. The DCE-MRI parameters (volume transfer coefficient [K(trans) ], reverse reflux rate constant [Kep ], extracellular extravascular volume fraction [Ve ], and initial area under the gadolinium concentration curve during the first 60 seconds [iAUC]) of gastric cancer and normal wall were measured and compared with each other using the Wilcoxon signed rank test. The relationship between the DCE-MRI parameters of gastric cancer and the pathological prognostic factors were evaluated using the Mann-Whitney test or the Spearman rank correlation test. DCE-MRIs were of diagnostic quality in 22 patients (81.5%). Ve and iAUC were significantly higher in gastric cancer than in normal gastric wall (P < 0.05). Ve showed significant positive correlation with T-staging of gastric cancers (P < 0.05). K(trans) was significantly correlated with the grades of epidermal growth-factor receptor expression (P < 0.05). DCE-MRI using a radial GRE with KWIC reconstruction is feasible for quantification of the perfusion dynamics of gastric cancers, and the DCE-MRI parameters of gastric cancers may provide prognostic information.

Purpose To compare arterial spin labeling (ASL) data between low- and high-grade brain tumors in children to establish a cutoff to distinguish low- from high-grade neoplasms and to assess potential correlations between cerebral blood flow (CBF) and quantitative histologic microvascular data. Materials and Methods Approval was obtained from the regional review board. ASL data obtained in 129 children between 2011 and 2015 were retrospectively analyzed. CBF and relative CBF in the most perfused area of each neoplasm and contrast enhancement were quantified with a semiquantitative ratio. The correlation between CBF and microvascular density was analyzed in specimens stained with anti-CD34. Results were controlled in two validation cohorts with 1.5- and 3.0-T magnetic resonance (MR) imaging. Results Mean CBF was significantly higher for high-grade than for low-grade hemispheric (116 mL/min/100 g [interquartile range {IQR}, 73-131 mL/min/100 g] vs 29 mL/min/100 g [IQR, 23-35 29 mL/min/100 g], P < .001), thalamic (87 mL/min/100 g [IQR, 73-100 mL/min/100 g] vs 36 mL/min/100 g [IQR, 30-40 mL/min/100 g], P = .016), and posterior fossa (59 mL/min/100 g [IQR, 45-91 mL/min/100 g] vs 33 mL/min/100 g [IQR, 25-40 mL/min/100 g], P < .001) tumors. With a cutoff of 50 mL/min/100 g, sensitivity and specificity were 90% (95% confidence interval [CI]: 68, 100) and 93% (95% CI: 66, 100), respectively, for hemispheric tumors; 100% (95% CI: 48, 100) and 80% (95% CI: 28, 100), respectively, for thalamic tumors; and 65% (95% CI: 51, 78) and 94% (95% CI: 80, 99), respectively, for posterior fossa tumors. In posterior fossa tumors, additional use of the CBF-to-contrast enhancement ratio yielded sensitivity and specificity of 96% (95% CI: 87, 100) and 97% (95% CI: 84, 100), respectively. Use of a simple algorithm based on these values yielded an accuracy of 93% (95% CI: 87, 97). Validation sets yielded similar results, with grading accuracy of 88% (95% CI: 62, 98) with 1.5-T MR imaging and 77% (95% CI: 46, 95) with 3.0-T MR imaging. CBF was strongly correlated with microvascular density (R = 0.66, P < .001). Conclusion High-grade pediatric brain tumors display higher CBF than do low-grade tumors, and they may be accurately graded by using these values. CBF is correlated with tumor microvascular density. © RSNA, 2016 Online supplemental material is available for this article.