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PurposeTo investigate the efficacy of diffusion-weighted imaging (DWI) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) for the early prediction of the pathologic response to neoadjuvant chemotherapy (NAC) in patients with locally advanced gastric cancer (LAGC).MethodsFifty patients with LAGC who were treated with NAC followed by radical gastrectomy were enrolled. Uncontrasted and DCE-MRI were performed within 1 week before NAC. According to tumor regression grading (TRG), patients were labeled as responders (TRG = 0 + 1) and non-responders (TRG = 2 + 3). Apparent diffusion coefficients (ADC) and DCE-MRI kinetics (Ktrans, Ve, and Kep) were compared between the two groups. Logistic regression analysis was performed to screen independent factors to predict the NAC efficacy. The relationship between MRI parameters and TRG was studied by Spearman’s correlation analysis. Receiver-operating characteristic curve analyses were applied to evaluate the efficacy.ResultsADC, Ktrans, and Kep values were higher in responders than in non-responders (p < 0.05) and correlated with TRG (p < 0.05). The ADC and Kep values were independent markers for predicting TRG. The area under the curve, sensitivities, specificities of ADC, Ktrans, Kep, and ADC + Kep were 0.813, 0.699, 0.709, 0.886;73.64%, 65.54%, 63.21%, 70.37%; 86.47%, 54.97%, 79.47%, 95.65%; respectively. ADC + Kep demonstrated a higher efficacy than Ktrans and Kep (p = 0.012, 0.011), but without improvement compared with ADC (p > 0.05).ConclusionBoth DWI and DCE-MRI can effectively predict the pathologic response to NAC in LAGC. A combination of ADC and Kep increased the efficacy, and ADC is the most valuable imaging parameter.

Background Accurate differentiation of pseudoprogression (PsP) from tumor progression (TP) in glioblastomas (GBMs) is essential for appropriate clinical management and prognostication of these patients. In the present study, we sought to validate the findings of our previously developed multiparametric MRI model in a new cohort of GBM patients treated with standard therapy in identifying PsP cases. Methods Fifty-six GBM patients demonstrating enhancing lesions within 6 months after completion of concurrent chemo-radiotherapy (CCRT) underwent anatomical imaging, diffusion and perfusion MRI on a 3 T magnet. Subsequently, patients were classified as TP + mixed tumor (n = 37) and PsP (n = 19). When tumor specimens were available from repeat surgery, histopathologic findings were used to identify TP + mixed tumor (> 25% malignant features; n = 34) or PsP (< 25% malignant features; n = 16). In case of non-availability of tumor specimens, ≥ 2 consecutive conventional MRIs using mRANO criteria were used to determine TP + mixed tumor (n = 3) or PsP (n = 3). The multiparametric MRI-based prediction model consisted of predictive probabilities (PP) of tumor progression computed from diffusion and perfusion MRI derived parameters from contrast enhancing regions. In the next step, PP values were used to characterize each lesion as PsP or TP+ mixed tumor. The lesions were considered as PsP if the PP value was < 50% and TP+ mixed tumor if the PP value was ≥ 50%. Pearson test was used to determine the concordance correlation coefficient between PP values and histopathology/mRANO criteria. The area under ROC curve (AUC) was used as a quantitative measure for assessing the discriminatory accuracy of the prediction model in identifying PsP and TP+ mixed tumor. Results Multiparametric MRI model correctly predicted PsP in 95% (18/19) and TP+ mixed tumor in 57% of cases (21/37) with an overall concordance rate of 70% (39/56) with final diagnosis as determined by histopathology/mRANO criteria. There was a significant concordant correlation coefficient between PP values and histopathology/mRANO criteria (r = 0.56; p < 0.001). The ROC analyses revealed an accuracy of 75.7% in distinguishing PsP from TP+ mixed tumor. Leave-one-out cross-validation test revealed that 73.2% of cases were correctly classified as PsP and TP + mixed tumor. Conclusions Our multiparametric MRI based prediction model may be helpful in identifying PsP in GBM patients.

Design of novel nanoplatforms with single imaging elements for dynamic and enhanced T1/T2‐weighted magnetic resonance (MR) imaging of diseases still remains significantly challenging. Here, a facile strategy to synthesize light‐addressable ultrasmall Fe3O4 nanoparticles (NPs) that can form nanoclusters (NCs) under laser irradiation for enhanced and dynamic T1/T2‐weighted MR imaging of inflammatory arthritis is reported. Citric acid‐stabilized ultrasmall Fe3O4 NPs synthesized via a solvothermal approach are linked with both the arthritis targeting ligand folic acid (FA) and light‐addressable unit diazirine (DA) via polyethylene glycol (PEG) spacer. The formed ultrasmall Fe3O4‐PEG‐(DA)‐FA NPs are cytocompatible, display FA‐mediated targeting specificity to arthritis‐associated macrophage cells, and can form NCs upon laser irradiation to have tunable r1 and r2 relaxivities by varying the laser irradiation duration. With these properties owned, the designed Fe3O4‐PEG‐(DA)‐FA NPs can be used for T1‐weighted MR imaging of arthritis without lasers and enhanced dual‐mode T1/T2‐weighted MR imaging of arthritis under laser irradiation due to the formation of NCs that have extended accumulation within the arthritis region and limited intravasation back to the blood circulation. The designed light‐addressable Fe3O4‐PEG‐(DA)‐FA NPs may be used as a promising platform for dynamic and precision T1/T2‐weighted MR imaging of other diseases. Light‐addressable ultrasmall iron oxide nanoparticles (NPs) are designed via linking of targeting ligand folic acid and light‐addressable unit diazirine onto the particle surface. These NPs possess desired cytocompatibility and targeting specificity to arthritis‐associated macrophage cells, and can generate nanoclusters upon laser irradiation to display tunable r1 and r2 relaxivities, thus enabling enhanced dual‐mode T1/T2‐weighted magnetic resonance imaging of inflammatory arthritis.

Objectives We evaluated the combined use of intravoxel incoherent motion (IVIM) and time-signal intensity curve (TIC) analyses to diagnose head and neck tumours. Methods We compared perfusion-related parameters ( PP ) and molecular diffusion values ( D ) determined from IVIM theory and TIC profiles among 92 tumours with different histologies. Results IVIM parameters ( f and D values) and TIC profiles in combination were distinct among the different types of head and neck tumours, including squamous cell carcinomas (SCCs), lymphomas, malignant salivary gland tumours, Warthin’s tumours, pleomorphic adenomas and schwannomas. A multiparametric approach using both IVIM parameters and TIC profiles differentiated between benign and malignant tumours with 97 % accuracy and diagnosed different tumour types with 89 % accuracy. Conclusions Combined use of IVIM parameters and TIC profiles has high efficacy in diagnosing head and neck tumours. Key points • Head and neck tumours have wide MR perfusion/diffusion properties. • Dynamic contrast-enhanced (DCE) MR imaging can characterise tumour perfusion (TIC analysis). • Intravoxel incoherent motion (IVIM) imaging can provide diffusion and perfusion properties. • However, IVIM or DCE imaging alone is insufficient for diagnosing head/neck tumours. • Multiparametric approach using both IVIM and TIC profiles can facilitate the diagnosis.

Glioblastoma (GBM) is the most malignant brain tumor in adults, with a dismal prognosis despite aggressive multi-modal therapy. Immunotherapy is currently being evaluated as an alternate treatment modality for recurrent GBMs in clinical trials. These immunotherapeutic approaches harness the patient’s immune response to fight and eliminate tumor cells. Standard MR imaging is not adequate for response assessment to immunotherapy in GBM patients even after using refined response assessment criteria secondary to amplified immune response. Thus, there is an urgent need for the development of effective and alternative neuroimaging techniques for accurate response assessment. To this end, some groups have reported the potential of diffusion and perfusion MR imaging and amino acid-based positron emission tomography techniques in evaluating treatment response to different immunotherapeutic regimens in GBMs. The main goal of these techniques is to provide definitive metrics of treatment response at earlier time points for making informed decisions on future therapeutic interventions. This review provides an overview of available immunotherapeutic approaches used to treat GBMs. It discusses the limitations of conventional imaging and potential utilities of physiologic imaging techniques in the response assessment to immunotherapies. It also describes challenges associated with these imaging methods and potential solutions to avoid them.

Clinical evidence regarding the value of MRI for therapy responses assessment in breast cancer is increasing. The objective of this study is to compare the diagnostic capability of diffusion-weighted MR imaging (DW-MRI) and contrast-enhanced MR imaging (CE-MRI) to evaluate and predict pathological response in breast cancer patients receiving neoadjuvant chemotherapy (NAC). We performed a meta-analysis of all available studies of the diagnostic performance of DW-MRI or CE-MRI to evaluate and predict pathological response to NAC in patients with breast cancer. We determined sensitivities and specificities across studies, calculated positive and negative likelihood ratios (LR+ and LR−), diagnostic odds ratio (DOR) and constructed summary receiver operating characteristic curves using hierarchical regression models. Methodological quality was assessed by QUADAS tool. Thirty-four studies met the inclusion criteria and involved 1,932 pathologically confirmed patients in total. Methodological quality was relatively high. DW-MRI sensitivity was 0.93 (95 % CI 0.82–0.97) and specificity was 0.82 (95 % CI 0.70–0.90). Overall LR+ was 5.09 (95 % CI 3.09–8.38), LR− was 0.09 (95 % CI 0.04–0.22), and DOR was 55.59 (95 % CI 21.80–141.80). CE-MRI sensitivity was 0.68 (95 % CI 0.57–0.77) and specificity was 0.91 (95 % CI 0.87–0.94). Overall LR+ was 7.48 (95 % CI 5.29–10.57), LR− was 0.36 (95 % CI 0.27–0.48), and DOR was 20.98 (95 % CI 13.24–33.24). Our study confirms that DW-MRI is a high sensitive and CE-MRI is a high specific modality in predicting pathological response to NAC in breast cancer patients. The combined use of DW-MRI and CE-MRI has the potential to improve the diagnostic performance in monitoring NAC. Further large prospective studies are warranted to assess the actual value of this combination in breast cancer preoperative treatment screening.

Cartilage repair techniques and pharmacological therapies are currently areas of major clinical interest and research, in particular to prevent and treat osteoarthritis. MR imaging-based techniques to visualize cartilage are prerequisites to guide and monitor these therapies. In this review article, standard MR imaging sequences are described, including proton density-weighted fast spin echo, spoiled gradient echo and dual echo steady state sequences. In addition, new sequences that have been developed and are currently being investigated are presented, including driven equilibrium Fourier transform and steady-state free precession-based imaging. Using high-field MR imaging at 3.0-T, visualization of cartilage and the related pathology has been improved. Volumetric quantitative cartilage MR imaging was developed as a tool to monitor the progression of osteoarthritis and to evaluate new pharmacological cartilage protective therapies. The most exciting developments, however, are in the field of cartilage matrix assessment with quantitative dGEMRIC, T2 and T1rho mapping techniques. These techniques aim at detecting cartilage damage at a stage when changes are potentially still reversible, before cartilage tissue is lost. There is currently substantial interest in these techniques from rheumatologists and orthopedists; radiologists therefore need to keep up with these developments.

Purpose To determine the correlation between intravoxel incoherent motion (IVIM) and dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) parameters. Methods Thirty-eight newly diagnosed NPC patients were prospectively enrolled. Diffusion-weighted images (DWI) at 13 b -values were acquired using a 3.0-T MRI system. IVIM parameters including the pure molecular diffusion ( D ), perfusion-related diffusion ( D* ), perfusion fraction ( f ), DCE-MRI parameters including maximum slope of increase (MSI), enhancement amplitude (EA) and enhancement ratio ( ER ) were calculated by two investigators independently. Intra- and interobserver agreement were evaluated using the intraclass correlation coefficient ( ICC ) and Bland-Altman analysis. Relationships between IVIM and DCE-MRI parameters were evaluated by calculation of Spearman’s correlation coefficient. Results Intra- and interobserver reproducibility were excellent to relatively good (ICC  =  0.887-0.997; narrow width of 95 % limits of agreement). The highest correlation was observed between f and EA ( r  = 0.633, P  < 0.001), with a strong correlation between f and MSI ( r  = 0.598, P  = 0.001). No correlation was observed between f and ER ( r  = -0.162; P  = 0.421) or D* and DCE parameters ( r  = 0.125–0.307; P  > 0.119). Conclusion This study suggests IVIM perfusion imaging using 3.0-T MRI is feasible in NPC, and f correlates significantly with EA and MSI. Key Points • Assessment of tumour perfusion is important in nasopharyngeal carcinoma . • DCE-MRI provided perfusion information with the use of intravenous contrast media . • Perfusion information could be provided by non-invasive IVIM MRI . • IVIM parameter f correlated with DCE-MRI parameters .

Background Radiation-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. Methods Eighteen 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. Results From 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). Conclusions Early radiation-induced changes of parotid glands could be evaluated by IVIM and DCE MR imaging. Certain IVIM and DCE MR parameters were correlated significantly.

Purpose To evaluate diffusion-weighted MR imaging (DWI) in the diagnosis of lymph node metastases in patients with cholangiocarcinoma. Methods In 24 patients with cholangiocarcinoma, MR imaging of the upper abdomen was performed prior to surgery at 1.5 T using a respiratory-triggered single-shot echo-planar imaging (SSEPI) sequence ( b values: 50, 300, and 600 s/mm 2 ). ADC (apparent diffusion coefficient) values and diameters of regional lymph nodes (LN) were determined. Subsequently, in all patients, surgical exploration and/or resection of the primary tumor and regional LN dissection were performed. Imaging results were correlated with results of histopathologic analysis. ADC values and diameters of benign and malignant LN were compared using the Mann–Whitney U test. In addition, a ROC (receiver operating characteristic curve) analysis was performed. Results The mean ADC value (×10 −3 mm 2 /s) of metastatic LN (1.21 ± 0.15) was significantly lower than that of benign LN (1.62 ± 0.33, p  < 0.001) while there was no significant difference in the mean diameter of malignant (16.8 ± 5.4 mm) and benign LN (14.1 ± 4.0 mm; p  = 0.09). Using an ADC value of 1.25 × 10 −3  mm 2 /s as threshold, 91.4% of LN were correctly classified as benign or malignant with a sensitivity/specificity of 83.3%/92.8% and a positive/negative predictive value of 66.7%/96.7%. The area under the ROC curve was 0.93. Conclusion DWI using a respiratory-triggered SSEPI sequence, according to our preliminary experience, is a promising imaging modality in the differentiation of benign and malignant LN in patients with cholangiocarcinoma.