Diffusion-weighted Magnetic Resonance Imaging Parameters Research Articles

Diffusion weighted MRI and neutrophil lymphocyte ratio non-invasively predict infection in pancreatic necrosis: a pilot study.

Infected pancreatic necrosis (IPN) is a major determinant of mortality in acute pancreatitis (AP). Non-invasive diagnosis of IPN could guide the intervention in AP. We aimed to investigate the role of non-invasive methods like diffusion weighted magnetic resonance imaging (DW-MRI) and clinico-laboratory parameters as predictors of IPN. Prospective evaluation for predictors of IPN by diffusion restriction (DR) on DW-MRI and clinico-laboratory parameters was performed. Out of 39 patients included, 31 were analysed after exclusion. Twenty-six (83.8%) patients had moderately severe AP, and the rest had severe disease. They were categorized into Group A: patients with documented infection after intervention (n = 17) and Group B: successfully managed without intervention or negative culture after intervention (n = 14). On univariate analysis, Group A had significantly more incidence of fever (P = 0.020), persistent unwellness (P = 0.003), elevated neutrophil count (P = 0.007), lymphocyte count (P = 0.007), neutrophil lymphocyte ratio (NLR) (P = 0.028), DR on DW-MRI (P = 0.001) and low apparent diffusion coefficient (ADC) (P = 0.086). Multivariate analysis revealed DR on DW-MRI (P = 0.004) and NLR (P = 0.035) as significant predictors of IPN, among other factors. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of DW-MRI were 94.1%, 78.6%, 91.66%, and 84.21%, respectively. The area under curve of NLR on the ROC plot was 0.85 and the best cutoff was >3.5, with sensitivity, specificity, PPV, and NPV of 70.6%, 78.6%, 80%, and 68.7% respectively. DW-MRI and NLR are promising non-invasive tools for accurate prediction of IPN and hence can guide the need for intervention in acute pancreatitis.

Spatial profiling of in vivo diffusion-weighted MRI parameters in the healthy human kidney.

Diffusion-weighted MRI is a technique that can infer microstructural and microcirculatory features from biological tissue, with particular application to renal tissue. There is extensive literature on diffusion tensor imaging (DTI) of anisotropy in the renal medulla, intravoxel incoherent motion (IVIM) measurements separating microstructural from microcirculation effects, and combinations of the two. However, interpretation of these features and adaptation of more specific models remains an ongoing challenge. One input to this process is a whole organ distillation of corticomedullary contrast of diffusion metrics, as has been explored for other renal biomarkers. In this work, we probe the spatial dependence of diffusion MRI metrics with concentrically layered segmentation in 11 healthy kidneys at 3 T. The metrics include those from DTI, IVIM, a combined approach titled "REnal Flow and Microstructure AnisotroPy (REFMAP)", and a multiply encoded model titled "FC-IVIM" providing estimates of fluid velocity and branching length. Fractional anisotropy decreased from the inner kidney to the outer kidney with the strongest layer correlation in both parenchyma (including cortex and medulla) and medulla with Spearman correlation coefficients and p-values (r, p) of (0.42, <0.001) and (0.37, <0.001), respectively. Also, dynamic parameters derived from the three models significantly decreased with a high correlation from the inner to the outer parenchyma or medulla with (r, p) ranges of (0.46-0.55, <0.001). These spatial trends might find implications for indirect assessments of kidney physiology and microstructure using diffusion MRI.

Identification of high-risk tumor characteristics in patients with localized prostate cancer using conventional combined with diffusion-weighted MRI imaging parameters.

The objective of this study was to investigate the utility of conventional imaging combined with diffusion-weighted magnetic resonance imaging (MRI) in identifying high-risk tumor characteristics in patients with localized prostate cancer. A retrospective cohort study was conducted on 194 patients who underwent surgery for localized prostate cancer. Patients were categorized into low-risk and high-risk groups based on clinical criteria. Imaging data were obtained using a MRI system, and various imaging parameters were analyzed, including T1-weighted imaging (T1WI), T2-weighted imaging (T2WI) signal intensities, diffusion-weighted MRI parameters, and their correlations with clinical characteristics. Statistical methods such as logistic regression, and receiver operating characteristic (ROC) analysis were employed to assess the diagnostic performance of the imaging parameters and to construct joint prediction models. A verification set prediction model was established and compared. The comparison of demographic and clinical characteristics between the low and high-risk groups revealed significant differences in the prostate-specific antigen (PSA) level, Gleason score, Tumor Size and prostate volume (PV). Standard imaging parameters, T1WI and T2WI signal intensities, exhibited significant differences between the low and high-risk groups. Additionally, diffusion-weighted MRI parameters, including signal intensities at different b values, apparent diffusion coefficient (ADC), Ktrans, and Kep, were notably associated with high-risk tumor characteristics in localized prostate cancer. Logistic regression analysis identified both standard imaging and diffusion-weighted MRI parameters as independent predictors of high-risk tumor characteristics. Furthermore, the ROC analysis demonstrated the diagnostic potential of T2WI signal intensity, signal intensity at 800 s/mm2, and ADC in identifying high-risk tumors. Joint prediction models combining standard imaging and diffusion-weighted MRI parameters showed high predictive accuracy for high-risk tumor characteristics in localized prostate cancer, with Area Under the Curve (AUC) values of 0.777 for standard imaging, 0.826 for diffusion-weighted MRI, and 0.892 for the combined model. The AUC value for the prediction model in validation set was 0.860. In conclusion, this study underscores the diagnostic potential of conventional imaging combined with diffusion-weighted MRI in identifying high-risk tumor characteristics in patients with localized prostate cancer. Both standard imaging and diffusion-weighted MRI parameters were identified as non-invasive biomarkers for risk assessment and prognosis. These findings have implications for precision treatment of localized prostate cancer, highlighting the potential integration of imaging-based risk assessment tools into clinical practice for tailored treatment strategies and improved patient outcomes.

Prediction of overall survival in patients with locally advanced pancreatic cancer using longitudinal diffusion-weighted MRI.

Biomarkers for prediction of outcome in patients with pancreatic cancer are wanted in order to personalize the treatment. This study investigated the value of longitudinal diffusion-weighted magnetic resonance imaging (DWI) for prediction of overall survival (OS) in patients with locally advanced pancreatic cancer (LAPC) treated with stereotactic body radiotherapy (SBRT). The study included 45 patients with LAPC who received 5 fractions of 10 Gy on a 1.5T MRI-Linac. DWI was acquired prior to irradiation at each fraction. The analysis included baseline values and time-trends of the apparent diffusion coefficient (ADC) and DWI parameters obtained using a decomposition method. A multivariable Cox proportional hazards model for OS was made using best-subset selection, using cross-validation based on Bootstrap. The median OS from the first day of SBRT was 15.5 months (95% CI: 13.2-20.6), and the median potential follow-up time was 19.8 months. The best-performing multivariable model for OS included two decomposition-based DWI parameters: one baseline and one time-trend parameter. The C-Harrell index describing the model's discriminating power was 0.754. High baseline ADC values were associated with reduced OS, whereas no association between the ADC time-trend and OS was observed. Decomposition-based DWI parameters indicated value in the prediction of OS in LAPC. A DWI time-trend parameter was included in the best-performing model, indicating a potential benefit of acquiring longitudinal DWI during the SBRT course. These findings support both baseline and longitudinal DWI as candidate prognostic biomarkers, which may become tools for personalization of the treatment of patients with LAPC.

Normalized Dynamic Contrast-enhanced Perfusion and Diffusion-weighted MRI Parameters Distinguish Head and Neck Cancer Recurrence from Posttreatment Changes.

Normalized Dynamic Contrast-enhanced Perfusion and Diffusion-weighted MRI Parameters Distinguish Head and Neck Cancer Recurrence from Posttreatment Changes.

Assessing Myocardial Microstructure With Biophysical Models of Diffusion MRI.

Biophysical models are a promising means for interpreting diffusion weighted magnetic resonance imaging (DW-MRI) data, as they can provide estimates of physiologically relevant parameters of microstructure including cell size, volume fraction, or dispersion. However, their application in cardiac microstructure mapping (CMM) has been limited. This study proposes seven new two-compartment models with combination of restricted cylinder models and a diffusion tensor to represent intra- and extracellular spaces, respectively. Three extended versions of the cylinder model are studied here: cylinder with elliptical cross section (ECS), cylinder with Gamma distributed radii (GDR), and cylinder with Bingham distributed axes (BDA). The proposed models were applied to data in two fixed mouse hearts, acquired with multiple diffusion times, q-shells and diffusion encoding directions. The cylinderGDR-pancake model provided the best performance in terms of root mean squared error (RMSE) reducing it by 25% compared to diffusion tensor imaging (DTI). The cylinderBDA-pancake model represented anatomical findings closest as it also allows for modelling dispersion. High-resolution 3D synchrotron X-ray imaging (SRI) data from the same specimen was utilized to evaluate the biophysical models. A novel tensor-based registration method is proposed to align SRI structure tensors to the MR diffusion tensors. The consistency between SRI and DW-MRI parameters demonstrates the potential of compartment models in assessing physiologically relevant parameters.

Diffusion-Weighted Magnetic Resonance Imaging of 103 Patients with Rectal Adenocarcinoma Identifies the Apparent Diffusion Coefficient as an Imaging Marker for Tumor Invasion and Regional Lymph Node Involvement.

BackgroundThis retrospective study included 103 patients diagnosed with rectal adenocarcinoma at a single center in Poland who underwent preoperative diffusion-weighted magnetic resonance imaging (DWI) and aimed to determine whether the apparent diffusion coefficient (ADC) was an imaging marker for tumor invasion and regional lymph node involvement.Material/MethodsWe analyzed primary staging magnetic resonance examinations of the rectum of 103 consecutive patients with histologically proven non-mucinous adenocarcinoma who underwent surgical treatment. In 85 patients, surgery was preceded by long-course chemoradiotherapy (n=18) or short-course radiotherapy (n=67). The following DWI parameters were measured: ADC mean, minimum, maximum, and standard deviation in the region of interest (ADC SD-in-ROI). Values were compared between subgroups based on histological parameters from the report: tumor stage, lymph node stage, differentiation grade, the presence of extranodal tumor deposits, angioinvasion, and perineural invasion. Statistical analysis was performed using the Mann-Whitney U test and the unilateral t test.ResultsADC mean values were lower for cases in which postoperative histopathological examination lymph node invasion (P=0.04) and tumor deposits were found (P=0.04). Minimal ADC value was higher in cases in which tumor deposits were not found (P=0.009). ADC SD-in-ROI values were lower in cases in which lymph nodes invasion was confirmed (P=0.014). There were no statistically significant differences for other parameters.ConclusionsThe ADC values in pre-treatment DWI in patients with rectal adenocarcinoma were correlated with tumor invasion and regional lymph node metastases. Therefore, ADC values from the pre-treatment MRI may help plan adjuvant therapy in patients with rectal adenocarcinoma.

Analysis of tumour microstructure estimation from conventional diffusion MRI and application to skull-base chordoma.

Skull-base chordoma (SBC) is a rare tumour whose molecular and radiological characteristics are still being investigated. In neuro-oncology microstructural imaging techniques, like diffusion-weighted MRI (DW-MRI), have been widely investigated, with the apparent diffusion coefficient (ADC) being one of the most used DW-MRI parameters due to its ease of acquisition and computation. ADC is a potential biomarker without a clear link to microstructure. The aim of this work was to derive microstructural information from conventional ADC, showing its potential for the characterisation of skull-base chordomas. Sixteen patients affected by SBC, who underwent conventional DW-MRI were retrospectively selected. From mono-exponential fits of DW-MRI, ADC maps were estimated using different sets of b-values. DW-MRI signals were simulated from synthetic substrates , which mimic the cellular packing of a tumour tissue with well-defined microstructural features. Starting from a published method, an error-driven procedure was evaluated to improve the estimates of microstructural parameters obtained through the simulated signals. A quantitative description of the tumour microstructure was then obtained from the DW-MRI images. This allowed successfully differentiating patients according to histologically-verified cell proliferation information.Clinical Relevance - The impact on cancer management derives from the expected improvement of radiation treatment quality tailored to a patient-specific non-invasive description of tumour microstructure.

Correlation between 18F-FDG PET/CT and diffusion-weighted MRI parameters in head and neck squamous cell carcinoma at baseline and after chemo-radiotherapy. A retrospective single institutional study.

The relationship between glucose metabolism and tumor cellularity before chemo-radiotherapy in patients with head and neck squamous cell carcinoma (SCC) has never been compared with that of patients evaluated after treatment. This retrospective study analyzed the correlation between glucose metabolism parameters expressed by standardized uptake value (SUV) derived from 18F-fluorodeoxyglucose (18F-FDG) PET/CT and cellularity tumor parameters expressed by apparent diffusion coefficients (ADC) derived from diffusion-weighted (DW) MRI in untreated and treated patients with head and neck SCC. In 19 patients with no previous exposure to any treatment and 17 different chemo-radiotreated patients with head and neck SCC, we correlated the semi-quantitative uptake values (SUVmax, SUVpeak, and SUVmean) with the ADC functional parameters (ADCmin, ADCmean) including the standard deviation of ADC values (ADCsd). No significant correlation was found between glucose metabolism parameters and ADCmin or ADCmean in untreated and treated patient groups. However, in untreated patients, significant inverse correlations were found between ADCsd and SUVmax (P = 0.039, r = -0.476), SUVpeak (P = 0.003, r = -0.652) and SUVmean (P = 0.039, r = -0.477). Analyses after chemo-radiotherapy in 17 patients showed no significant correlation between glucose metabolism parameters and DW MRI values, excluding a persistent significant (but lower intensity) inverse correlation between SUVpeak and ADCsd (P = 0.033, r = -0.519). The demonstrated relationships suggest complex interactions especially between metabolic activity and heterogeneity of tumoral tissue, which might play a complementary role in the assessment of head and neck SCC. Our retrospective study was registered on April 9th, 2020 by the Ethics Committee of the Coordinating Center "Area Vasta Nord Ovest" (CEAVNO) with Registration Number CEAVNO09042020.

Diffusion-weighted MRI for predicting pathologic response to neoadjuvant chemotherapy in breast cancer: evaluation with mono-, bi-, and stretched-exponential models

BackgroundTo investigate the performance of diffusion-weighted (DW) MRI with mono-, bi- and stretched-exponential models in predicting pathologic complete response (pCR) to neoadjuvant chemotherapy (NACT) for breast cancer, and further outline a predictive model of pCR combining DW MRI parameters, contrast-enhanced (CE) MRI findings, and/or clinical-pathologic variables.MethodsIn this retrospective study, 144 women who underwent NACT and subsequently received surgery for invasive breast cancer were included. Breast MRI including multi-b-value DW imaging was performed before (pre-treatment), after two cycles (mid-treatment), and after all four cycles (post-treatment) of NACT. Quantitative DW imaging parameters were computed according to the mono-exponential (apparent diffusion coefficient [ADC]), bi-exponential (pseudodiffusion coefficient and perfusion fraction), and stretched-exponential (distributed diffusion coefficient and intravoxel heterogeneity index) models. Tumor size and relative enhancement ratio of the tumor were measured on contrast-enhanced MRI at each time point. Pre-treatment parameters and changes in parameters at mid- and post-treatment relative to baseline were compared between pCR and non-pCR groups. Receiver operating characteristic analysis and multivariate regression analysis were performed.ResultsOf the 144 patients, 54 (37.5%) achieved pCR after NACT. Overall, among all DW and CE MRI measures, flow-insensitive ADC change (ΔADC200,1000) at mid-treatment showed the highest diagnostic performance for predicting pCR, with an area under the receiver operating characteristic curve (AUC) of 0.831 (95% confidence interval [CI]: 0.747, 0.915; P < 0.001). The model combining pre-treatment estrogen receptor and human epidermal growth factor receptor 2 statuses and mid-treatment ΔADC200,1000 improved the AUC to 0.905 (95% CI: 0.843, 0.966; P < 0.001).ConclusionMono-exponential flow-insensitive ADC change at mid-treatment was a predictor of pCR after NACT in breast cancer.

Clinical and demographic data improve diagnostic accuracy of dynamic contrast-enhanced and diffusion-weighted MRI in differential diagnostics of parotid gland tumors.

To verify if differential diagnostic algorithms based on selected parameters of dynamic and diffusion-weighted MRI, clinical and demographic variables are accurate enough to differentiate between parotid malignancies, pleomorphic adenomas and Warthin tumors. The study included 84 patients, among them 19 (23%) with postoperative diagnosis of a parotid malignancy, 37 (44%) with Warthin tumors and 28 (33%) with pleomorphic adenomas. Accuracy of dynamic and diffusion-weighted MRI parameters (Tpeak, Tmax, WR and ADC), clinical parameters of the tumor (location in the superficial or deep parotid lobe, single vs. multiple lesion, concomitant lymphadenopathy) and demographic characteristics of the patient (age, sex) was determined on ROC analysis. Compared to Warthin tumors, parotid malignancies showed higher Tpeak, Tmax and ADC, lower WR, were more often located in the deep lobe of the parotid and presented as single lesions with concomitant lymphadenopathy. Consideration of all these variables provided 100% sensitivity and 89.2% specificity of the differential diagnostic algorithm. Compared to pleomorphic adenomas, parotid malignancies presented with lower ADC and Tpeak, higher Tmax, were more often located in the deep lobe of the parotid, associated with concomitant lymphadenopathy, diagnosed in men and individuals older than 66years. Consideration of all these variables provided 100% sensitivity and 96.4% specificity of the differential diagnostic algorithm. Combined analysis of clinical data and results of dynamic and diffusion-weighted MRI may provide nearly ideal accuracy in differential diagnostics of parotid malignancies and the two most common histological types of benign tumors.

MP80-01 RADIOPROTEOMIC ANALYSIS AS A POTENTIAL PREDICTOR OF RENAL TUMOR HISTOPATHOLOGY

You have accessJournal of UrologyKidney Cancer: Epidemiology & Evaluation/Staging/Surveillance III (MP80)1 Apr 2020MP80-01 RADIOPROTEOMIC ANALYSIS AS A POTENTIAL PREDICTOR OF RENAL TUMOR HISTOPATHOLOGY Jorge Daza*, Berengere Salome, Octavia Bane, Sara Lewis, John Sfakianos, Andrew Charap, Kirolos N. Meilika, Bheesham Dayal, Kennedy Okhawere, Ketan Badani, and Amir Horowitz Jorge Daza*Jorge Daza* More articles by this author , Berengere SalomeBerengere Salome More articles by this author , Octavia BaneOctavia Bane More articles by this author , Sara LewisSara Lewis More articles by this author , John SfakianosJohn Sfakianos More articles by this author , Andrew CharapAndrew Charap More articles by this author , Kirolos N. MeilikaKirolos N. Meilika More articles by this author , Bheesham DayalBheesham Dayal More articles by this author , Kennedy OkhawereKennedy Okhawere More articles by this author , Ketan BadaniKetan Badani More articles by this author , and Amir HorowitzAmir Horowitz More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000000972.01AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Renal biopsy is the available option to evaluate tumor characteristics in small renal masses (SMRs). However, this technique has some drawbacks including potential complications and false negative results due to tumor heterogeneity. We aim to show a novel and comprehensive approach composed by multiparametric magnetic resonance imaging (mpMRI) and high throughput proteome analysis in urine and blood from patients with SMRs that can potentially be a novel diagnostic tool to identify benign or indolent tumors. METHODS: A cohort of 16 patients who underwent robotic partial nephrectomy (RPN) had a mpMRI. Histogram measures of diffusion-weighted MRI parameters in the tumor were compared between tumor subtypes by Mann-Whitney tests and one-way ANOVA. A high throughput analysis of the plasma and urine proteome using a panel of 92 inflammation related markers from Olink proteomics was obtained in 14 out 16 patients with previous mpMRI. Samples were collected at the day of surgery. NPX values for the biomarkers were compared across patients with benign, clear cell renal cell carcinoma (ccRCC) and non-ccRCC. T-test, p-value< 0.05 was considered statistically significant). RESULTS: Mean (p=0.048) and median (p=0.034) apparent diffusion coefficient (ADC), and mean (p=0.048) and median (p=0.048) diffusion parameter D were significantly elevated in ccRCC versus other subtypes. Protein expression clustering analysis of the markers with significant differential expression across the groups showed a predominant upregulation of the inflammation markers in ccRCC cases in urine (Fig 1). On the other hand, protein expression in plasma showed clustering of benign cases with a predominant downregulation of the analytes from the panel. Interestingly, when comparing ccRCC vs non-ccRCC, the latter cluster in a subset of cases with upregulation of inflammatory markers (Fig 2). CONCLUSIONS: Radioproteomic analysis showed to be a promising approach to differentiate across ccRCC, non-ccRCC and benign tumors and guide therapeutic approaches to different subtypes of RCC. Source of Funding: None © 2020 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 203Issue Supplement 4April 2020Page: e1224-e1224 Advertisement Copyright & Permissions© 2020 by American Urological Association Education and Research, Inc.MetricsAuthor Information Jorge Daza* More articles by this author Berengere Salome More articles by this author Octavia Bane More articles by this author Sara Lewis More articles by this author John Sfakianos More articles by this author Andrew Charap More articles by this author Kirolos N. Meilika More articles by this author Bheesham Dayal More articles by this author Kennedy Okhawere More articles by this author Ketan Badani More articles by this author Amir Horowitz More articles by this author Expand All Advertisement PDF downloadLoading ...

Preoperative Prediction of Pathologic Response to Neoadjuvant Chemoradiotherapy in Patients With Esophageal Cancer Using 18F-FDG PET/CT and DW-MRI: A Prospective Multicenter Study

Accurate preoperative prediction of pathologic response to neoadjuvant chemoradiotherapy (nCRT) in patients with esophageal cancer could enable omission of esophagectomy in patients with a pathologic complete response (pCR). This study aimed to evaluate the individual and combined value of 18F-fluorodeoxyglucose positron emission tomography with integrated computed tomography (18F-FDG PET/CT) and diffusion-weighted magnetic resonance imaging (DW-MRI) during and after nCRT to predict pathologic response in patients with esophageal cancer. In this multicenter prospective study, patients scheduled to receive nCRT followed by esophagectomy for esophageal cancer underwent 18F-FDG PET/CT and DW-MRI scanning before the start of nCRT, during nCRT, and before esophagectomy. Response to nCRT was based on histopathologic evaluation of the resection specimen. Relative changes in 18F-FDG PET/CT and DW-MRI parameters were compared between patients with pCR and non-pCR groups. Multivariable ridge regression analyses with bootstrapped c-indices were performed to evaluate the individual and combined value of 18F-FDG PET/CT and DW-MRI. pCR was found in 26.1% of 69 patients. Relative changes in 18F-FDG PET/CT parameters after nCRT (Δ standardized uptake value [SUV]mean,postP = .016, and Δ total lesion glycolysis postP = .024), as well as changes in DW-MRI parameters during nCRT (Δ apparent diffusion coefficient [ADC]duringP = .008) were significantly different between pCR and non-pCR. A c-statistic of 0.84 was obtained for a model with ΔADCduring, ΔSUVmean,post, and histology in classifying patients as pCR (versus 0.82 for ΔADCduring and 0.79 for ΔSUVmean,post alone). Changes on 18F-FDG PET/CT after nCRT and early changes on DW-MRI during nCRT can help identify pCR to nCRT in esophageal cancer. Moreover, 18F-FDG PET/CT and DW-MRI might be of complementary value in the assessment of pCR.

Final Trial Results of Repeated Diffusion-Weighted MRI and FDG-PET Imaging for the Prediction of Response to Chemoradiation Therapy in Esophageal Cancer

To present the final results of a prospective study to evaluate imaging predictors for pathologic complete response (pathCR) to chemoradiation therapy (CRT) in esophageal cancer using repeated diffusion-weighted magnetic resonance imaging (DW-MRI) and 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) imaging before, during, and after CRT. Between January 2014 and July 2017, 60 patients with stage II-III esophageal cancer were prospectively enrolled. DW-MRI and FDG-PET imaging were acquired before treatment (baseline), 12-14 days after initiation of CRT (interim, IM), and at first follow-up 4-6 weeks after completing CRT. The primary outcome was pathCR as assessed after subsequent surgery, with secondary outcomes evaluating locoregional and distant progression-free survival (LPFS and DPFS), and overall survival (OS) according to the imaging parameters. Logistic regression analysis was used to evaluate the association of primary tumor apparent diffusion coefficient (ADC) values, maximum and mean standardized uptake value (SUV), metabolic tumor volume (MTV), and tumor lesion glycolysis (TLG) at baseline and their relative changes (Δ) at interim and follow-up scans with pathCR. Survival analyses applied to evaluate the association of the imaging parameters with LPFS, DPFS, and OS. Surgery after CRT was performed in 29 (48%) of 60 included patients. Imaging data was eligible for analysis in 28 patients in whom pathCR was observed in 7 (25%). The change in tumor mean ADC from the baseline to the interim DW-MRI scan, at a threshold of +27.7%, was best predictive for pathCR (c-statistic=0.98). The change in TLG from the baseline to interim FDG-PET scan, at a threshold of 58% decrease, was the best FDG-PET-based predictor of pathCR (c-statistic=0.77). Multivariable logistic regression suggested no significant added value of ΔTLGIM to ΔADCIM for the prediction of pathCR. Median follow-up was 29 months (range: 5-59) overall and 36 months (range: 24-59) for survivors. In surgical patients no locoregional progression was seen, and studied DW-MRI and FDG-PET parameters were not significantly associated with DPFS or OS. For non-surgical patients with ΔADCIM above vs below +27.7%, observed locoregional recurrence rates were 1/5 (20%) vs 7/25 (28%) (NS), and distant recurrence rates were 1/5 (20%) vs 15/25 (60%) (NS). For non-surgical patients with ΔTLGIM below vs above -58%, observed locoregional recurrence rates were 2/11 (18%) vs 5/17 (29%) (NS), and distant recurrence rates were 3/11 (27%) vs 12/17 (71%) (log-rank test, p=0.04). No association between imaging parameters and OS was observed. ΔADC on DW-MRI after 2 weeks of CRT strongly predicts pathologic complete response in esophageal cancer, with superior performance to repeated FDG-PET imaging. Early response assessment using DW-MRI is potentially useful for stratification of esophageal cancer patients to treatment intensification or organ-preserving strategies.

Post-radiotherapy apparent diffusion coefficient (ADC) in children and young adults with high-grade gliomas and diffuse intrinsic pontine gliomas

Objectives: Diffusion-weighted magnetic resonance imaging (DW-MRI) offers potential to monitor response and predict survival in high-grade gliomas (HGG) and diffuse intrinsic pontine gliomas (DIPG). We hypothesized that post-radiotherapy DW-MRI may provide prognostic imaging biomarkers in children and young adults with these tumors. Methods: Patients aged ≤21 years diagnosed between 2005 and 2012 were eligible. The tumor median apparent diffusion coefficient (ADC) and its 5th percentile (C5-ADC) were determined at the first post-radiotherapy scan and at the time of radiological progression. DW-MRI parameters were correlated with survival endpoints, temozolomide use and pseudoprogression, when it occurred. Results: Out of 40 patients (20 HGG, 20 DIPG), 23 had evaluable DW-MRI post-radiotherapy and 25 at radiological progression. There were 6 episodes of pseudoprogression. Hazard ratios (95%CI) for progression-free survival were 0.998 (0.993–1.003) for median ADC and 1.003 (0.996–1.010) for C5-ADC. Hazard ratios (95%CI) for overall survival were 1.0009 (0.996–1.006) for median ADC and 0.998 (0.992–1.004) for C5-ADC. Post-radiotherapy median and C5-ADC values were not significantly different between patients treated with radiotherapy alone versus radiotherapy/temozolomide. The median and C5-ADC values were not significantly different at the time of pseudoprogression compared to those at tumor progression. Conclusions: Post-radiotherapy median ADC and C5-ADC were not prognostic, nor able to differentiate radiosensitization with temozolomide or occurrence of pseudoprogression in this cohort of HGG and DIPG patients. Further exploration of alternative DW parameters, study timepoints or data modeling may contribute to the development of prognostic/predictive imaging biomarkers for children and young adults with HGG or DIPG.

Diffusion-weighted MRI and PET–CT in the follow up of chronic periaortitis

Aim of the present study is to compare magnetic resonance imaging (MRI) and positron emission tomography (PET) parameters in the follow up of chronic periaortitis (CP), with a focus on changes in the apparent diffusion coefficient (ADC) and standardized uptake values (SUV). 127 patients with CP were treated in our urology between 2007 and 2017. We identified 14 patients with parallel abdominal MRI and PET-CT examinations before therapy and in the follow up resulting in a total of 56 examinations. Relative contrast uptake and diffusion-weighted MRI parameters were compared to SUV in the corresponding PET-CT examinationsand laboratory infection markers. All examined MRI and PET-CT parameters showed significant changes between basis and follow-up examinations. Median ADC values increased significantly (p < 0.001) in the follow up. SUVmax and the other MR parameter (contrast uptake, DWI-signal) declined significantly. We observed a strong negative correlation between ADC and SUVmax (rho: - 0.61; p < 0.001). In addition, we found an inverse correlation of ADC with the inflammation markers ESR (rho: - 0.64; p < 0.001) and CRP (rho: - 0.54; p = 0.001). MRI and PET-CT showed comparable results in the individual follow up of CP and compared to laboratory inflammation markers. Our data support MRI as first imaging modality due to absent radiation and the necessity of repetitive follow-up examinations in patients with CP.

Abstract TP47: Prediction of Stroke Outcome With Immediate Post-Thrombolysis Magnetic Resonance Imaging

Background: Early recanalization and adequate collateral blood flow are strong surrogates for functional recovery in endovascular stroke treatment. We sought to evaluate the prognostic value of immediate post-thrombolysis magnetic resonance imaging (MRI). Methods: Consecutive patients with acute ischemic stroke who underwent endovascular treatment were enrolled. We measured diffusion-weighted MRI (DWI) and perfusion-weighted MRI (PWI) lesion volume, mismatch ratio, and DWI and PWI lesion volume change before and immediate after treatment. Outcome was measured with modified Rankin Scale (mRS) at 90 days, early neurological improvement (NIHSS ≥ 8) within 7 days, and any intracerebral hemorrhage. Multivariate analysis and c -statistics were used to identify prognostic value of MR parameters. Results: A total of 65 patients with a complete pre- and post-thrombolysis MRI were included. Mean age was 65±18 years, median baseline NIHSS score was 14, and median time from symptom onset to endovascular treatment was 192 minutes. Median time from endovascular treatment to post-treatment MRI was 20 minutes. After control of initial stroke severity and complete recanalization on angiography, post-thrombolysis PWI lesion volume remained an independent predictor of favorable outcome ( p = 0.017, odds ratio [OR] = 0.970, 95% confidence interval [CI] = 0.946-0.995), and early neurological improvement ( p = 0.014, OR = 0.957, 95% CI = 0.923-0.991), whereas DWI lesion volume, mismatch ratio, and DWI and PWI lesion volume changes did not show statistical significance. None of the measured variables predicts intracerebral hemorrhage. Post-thrombolysis PWI lesion volume revealed area under the curve of 0.821 (p &lt; 0.001, 95% CI = 0.722-0.920) for favorable outcome and 0.878 (p &lt; 0.001, 95% CI = 0.799-0.957) for early neurological improvement. Conclusions: Perfusion lesion volume on immediate post-thrombolysis MRI more accurately predicts functional recovery and early neurological improvement than pre-treatment DWI and PWI parameters.

Radioembolization Versus Bland Embolization for Hepatic Metastases from Small Intestinal Neuroendocrine Tumors: Short-Term Results of a Randomized Clinical Trial

BackgroundRadioembolization (RE) with intra-arterial administration of 90Y microspheres is a promising technique for the treatment of liver metastases from small intestinal neuroendocrine tumors (SI-NET) not amenable to surgery or local ablation. However, studies comparing RE to other loco-regional therapies are lacking. The aim of this randomized study was to compare the therapeutic response and safety after RE and bland hepatic arterial embolization (HAE), and to investigate early therapy-induced changes with diffusion-weighted MRI (DWI-MRI).MethodsEleven patients were included in a prospective randomized controlled pilot study, six assigned to RE and five to HAE. Response according to RECIST 1.1 using MRI or CT at 3 and 6 months post-treatment was recorded as well as changes in DWI-MRI parameters after 1 month. Data on biochemical tumor response, toxicity, and side effects were also collected.ResultsThree months after treatment, all patients in the HAE group showed partial response according to RECIST while none in the RE group did (p = 0.0022). After 6 months, the response rates were 4/5 (80%) and 2/6 (33%) in the HAE and RE groups, respectively (NS). DWI-MRI metrics could not predict RECIST response, but lower pretreatment ADC(120–800) and larger ADC(0–800) increase at 1 month were related to larger decrease in tumor diameter when all tumors were counted.ConclusionHAE resulted in significantly higher RECIST response after 3 months, but no difference compared to RE remained after 6 months. These preliminary findings indicate that HAE remains a safe option for the treatment of liver metastases from SI-NET, and further studies are needed to establish the role of RE and the predictive value of MR-DWI.

Selection for biopsy of kidney transplant patients by diffusion-weighted MRI.

To assess retrospectively whether diffusion-weighted magnetic resonance imaging (DW-MRI) allows physicians to determine the severity of histopathologic findings in biopsies of renal allograft patients with deteriorating renal function. Forty consecutive kidney transplant patients underwent DW-MRI and biopsy. Patients were assigned to one group with severe and to another group with normal or mild histopathologic findings. These two groups were compared based on a qualitative DW-MRI assessment (homo-/heterogeneity) and the combination of qualitative and quantitative DW-MRI parameters (ADC, and intravoxel incoherent motion, IVIM, parameters: D, f, D*). Sensitivity, specificity, and accuracy were determined for each parameter. Biopsy findings were severe in 25 patients and normal or mild in 15 patients. Qualitative DW-MRI led to a sensitivity of 44.0% and a specificity of 93.3%. Combined qualitative and quantitative DW-MRI led to an accuracy of 80% for both the minimal ADC (ADCmin) and the minimal perfusion fraction (fmin) with a sensitivity of 84.0% and 92.0% and a specificity of 73.3% and 60.0%, respectively. Combined qualitative and quantitative DW-MRI might allow physicians to determine the severity of histopathologic findings in biopsies of a high number of kidney transplant patients. • Qualitative DW-MRI is highly specific when predicting the severity of kidney transplant biopsy. • Allografts appearing heterogeneous on ADC are associated with severe histopathologic findings. • Combining qualitative and quantitative DW-MRI parameters improves the classification's sensitivity and accuracy. • Kidney transplant biopsies might be spared by combining qualitative and quantitative DW-MRI.

English

Background: Atypical and malignant meningiomas are associated with less favourable clinical outcome as they are more prone to recurrence and aggressive growth. Conventional magnetic resonance imaging (MRI) can reliably differentiate meningiomas from other extra-axial neoplasms, but grading of meningiomas as typical or atypical/malignant is not possible. Diffusion weighted MRI (DWMRI) has been used reliably for grading of gliomas. There are only few studies to investigate utility of DWMRI in grading of meningiomas. So we have planned in this study to investigate the utility of DWMRI parameters such as apparent diffusion coefficients (ADC) and normalized ADC (NADC) ratios in the preoperative characterization of meningiomas. Methods: Thirty patients with pathologically proven meningiomas [typical (n=25) atypical/malignant (n=5)] underwent MRI at 1.5 T. The signal intensity of lesions on DWI was evaluated. ADC values of lesion and NADC ratios from lesion and contralateral normal white matter were calculated. Results: The mean apparent diffusion constant (ADC) values (χ 10-3 mm2/ s) were 0.92±0.2 and 0.66±0.08 in typical and atypical/malignant meningiomas respectively. The mean NADC ratios were 1.24±0.28 and 0.86±0.08 for typical and atypical/malignant meningiomas respectively. Conclusions: Atypical and malignant meningiomas have significantly lower ADC and NADC ratios compared to typical meningiomas.