Diffusion-weighted Imaging MRI Research Articles

Utility of Non-EPI DWI MRI Imaging in Cholesteatoma: The Indian Perspective.

The purpose of this prospective observational study was to evaluate the diagnostic performance of non-EPI-based techniques, in detecting both primary and residual/recurrent cholesteatoma in a tertiary care center. 56 patients (25 female and 31 male) aged between 6 and 59years were prospectively evaluated for the presence or absence of cholesteatoma. This included both primary and postoperative recurrent cholesteatoma (16). All the patients underwent sequential CT scans of temporal bones and non-EPI DWI (Non-Echo Planar Diffusion-Weighted Imaging) MRI techniques. The findings were correlated with surgical findings regarding the presence or absence of cholesteatoma. The size of cholesteatoma that was diagnosed on non-EPI DWI MRI was measured. The smallest size was 6mm and the largest one was 21mm. The accuracy of non-EPI DWI MRI in diagnosing cholesteatoma (primary and recurrent) was 97.5%. Whereas in diagnosing recurrent cholesteatoma accuracy was 100%. Accuracy of non-EPI DWI MRI is very high in diagnosing cholesteatoma especially in recurrent cholesteatoma and can potentially replace second look surgery when intact canal wall techniques are used. The technique is best used with a CT Scan of the temporal bone to depict bony changes, anatomical variants, or complications. The combination of HRCT and non-EPI DWI needs to be employed in diagnosing primary and recurrent cholesteatoma to maximize the diagnostic benefit as they are complimentary.

Multicontrast MRI-based radiomics for the prediction of pathological complete response to neoadjuvant chemotherapy in patients with early triple negative breast cancer.

To assess pre-therapeutic MRI-based radiomic analysis to predict the pathological complete response to neoadjuvant chemotherapy (NAC) in women with early triple negative breast cancer (TN). This monocentric retrospective study included 75 TN female patients with MRI (T1-weighted, T2-weighted, diffusion-weighted and dynamic contrast enhancement images) performed before NAC. For each patient, the tumor(s) and the parenchyma were independently segmented and analyzed with radiomic analysis to extract shape, size, and texture features. Several sets of features were realized based on the 4 different sequence images. Performances of 4 classifiers (random forest, multilayer perceptron, support vector machine (SVM) with linear or quadratic kernel) were compared based on pathological complete response (defined on the excised tissues), on 100 draws with 75% as training set and 25% as test. The combination of features extracted from different MR images improved the classifier performance (more precisely, the features from T1W, T2W and DWI). The SVM with quadratic kernel showed the best performance with a mean AUC of 0.83, a sensitivity of 0.85 and a specificity of 0.75 in the test set. MRI-based radiomics may be relevant to predict NAC response in TN cancer. Our results promote the use of multi-contrast MRI sources for radiomics, providing enrich source of information to enhance model generalization.

Renal Diffusion-Weighted Imaging in Healthy Dogs: Reproducibility, Test-Retest Repeatability, and Selection of the Optimal b-value Combination.

Diffusion-weighted imaging (DWI) magnetic resonance imaging can evaluate alterations in the microstructure of the kidney. The purpose of this study was to assess the apparent diffusion coefficient (ADC) and the intravoxel incoherent motion model (IVIM) parameters of a normal kidney in healthy dogs, to evaluate the effect of b-value combinations on the ADC value, and the reproducibility and test-retest repeatability in monoexponential and IVIM analysis. In this experimental study, the ADC, pure diffusion coefficient (D), pseudodiffusion coefficient (D*), and perfusion fraction (f p) were measured from both kidneys in nine healthy beagles using nine b-values (b = 0, 50, 70, 100, 150, 200, 500, 800, and 1,000 s/mm2) twice with a 1-week interval between measurements. Interobserver and intraobserver reproducibility, and test-retest repeatability of the measurements were calculated. ADC values were measured using 10 different b-value combinations consisting of three b-values each, and were compared to the ADC obtained from nine b-values. All the ADC, D, D*, and f p values measured from the renal cortex, medulla, and the entire kidney had excellent interobserver and intraobserver reproducibility, and test-retest repeatability. The ADC obtained from a b-value combination of 0, 100, and 800 s/mm2 had the highest intraclass correlation coefficient with the ADC from nine b-values. The results of this study indicated that DWI MRI using multiple b-values is feasible for the measurement of ADC and IVIM parameters with high reproducibility and repeatability in the kidneys of healthy dogs. A combination of b = 0, 100, and 800 s/mm2 can be used for ADC measurements when multiple b-values are not available in dogs.

The Value of Combination of Dynamic Contrast-Enhanced Magnetic Resonance Imaging and Diffusion-Weighted Imaging in the Evaluation of Breast Masses

Aim of the study: The aim was to characterize benign and malignant breast lesions on the basis of their magnetic resonance imaging (MRI) morphology and dynamic contrast enhancement in combination with the diffusion-weighted imaging (DWI) and their apparent diffusion coefficient (ADC) values at 1.5 T MRI, along with histopathological correlation. Patients and Methods: In this prospective study, 56 patients with suspicious breast mass who underwent 1.5 T MRI and proved by histopathology were included. Morphology was studied depending on the MRI signal intensity and dynamic contrast-enhanced imaging plus kinetic curve of enhancement of breast lesions. DWI and ADC values were calculated at b values of 0, 600, and 850 s/mm. The ADC value and histopathology correlation were analyzed. Results: Out of the 56 lesions, 27 lesions were histologically malignant (48.2%) and 29 were histologically benign (51.8%), with age range between 25 and 75 years, with a mean of 54.1 years, and with a standard deviation of ±12.69 years. The MRI results found a sensitivity (SN) of 85.2%, a specificity (SP) of 72.4%, a positive predictive value (PPV) of 74.2%, a negative predictive value (NPV) of 84%, and an accuracy of 78.6%. The DWI findings were as follows: 100% SN, 82.8% SP, 84.4% PPV, 100% NPV, and 85.3% accuracy. The combined MRI interpretation and DWI and ADC findings were as follows: 100% SN, 92.1% SP, 71.1% PPV, 100% NPV, and 86.4% accuracy. All malignant lesions showed restriction at DWI, while only 17.2% of the benign lesions are restricted at DWI. The mean of ADC value was higher in benign cases as compared to the malignant lesions (0.815 vs. 1.287 × 10−3) with statistically significant difference (P = 0.001). Conclusions: The combination of contrast-enhanced breast MRI with DWI and ADC value increases the diagnostic accuracy and SP in the characterization of benign and malignant breast lesions.

The role of diffusion-weighted imaging MRI in differentiation between benign and malignant axillary lymphadenopathy in clinically TNM stages I and II breast cancer

Objective To investigate diffusion-weighted imaging (DWI) in differentiation of metastatic from nonmetastatic axillary lymph nodes (ALNs) in clinically stages I and II breast cancer. Patients and methods A total of 255 ALNs from 30 female patients with histologically proved breast cancer were assessed by 1.5 T scanner. DWI was implemented at b values of 50, 400, and 800 s/mm2. Short-axis diameter, presence of fatty hilum, and apparent diffusion coefficient (ADC) values (minimum and maximum and mean) of metastatic and nonmetastatic ALNs were compared. Cutoff ADC values to discriminate between benign and malignant ALNs were analyzed with receiver coefficient characteristic (receiver operating characteristic) curves. Results The final histopathological examination revealed 69.4% (n = 177) metastatic and 30.6% (n = 78) nonmetastatic ALNs. There was no statistically significant difference in short-axis diameter between the two groups (P = 0.82). However, there was a significantly correlation between loss of fatty hilum and presence of metastases (P Conclusion DWI-MRI and ADC values are promising imaging methods that can assess metastatic ALNs in early breast cancer with high sensitivity, specificity, and accuracy.

Novel method using DW-MRI and ADC images to guide stereotactic biopsy for the diagnosis small primary angiitis of the central nervous system: a case report

ObjectiveTo determine the role of diffusion-weighted magnetic resonance imaging (DW-MRI) and apparent diffusion coefficient (ADC) imaging to guide stereotactic biopsy for the diagnosis of intracranial angiitis.Case presentationIn a 28-year-old woman who had experienced inactive headache and right limbs numbness for 4 days, preoperative magnetic resonance (MR) scanning, enhanced scanning, diffusion tensor imaging, magnetic resonance spectroscopy, diffusion-weighted imaging (DWI), and ADC image scanning were performed. Stereotactic biopsy was performed in one target where the area of edema detected with MR FLAIR, and two targets where the area shown as a high-value and a lower value area in the DWI/ADC image. Pathological examinations together with computed tomographic and enhanced MRI scans were conducted after surgery. A preoperative enhanced MRI scan showed a uniform low-intensity lesion in the patient’s left centrum semiovale, with a volume of 3.1 cm3. The DWI and ADC images showed uneven high-intensity signals and different ADC values in the lesion area, respectively. During surgery, tissues around the lesion and the lesion center were sampled at the three selected targets. The postoperative pathological diagnosis was primary angiitis of the central nervous system, and the patient was given anti-inflammatory medication and hormone therapy. The 3-year follow-up confirmed that the patient had recovered well, with a Glasgow Outcome Scale score of five.ConclusionDW-MRI and ADC images can be reliably used to determine the location of small intracranial lesions, and guide stereotactic biopsy to facilitate the diagnosis of primary vasculitis of the central nervous system.

A Case of Acute Renal Failure with Severe Loin Pain and Patchy Renal Ischemia after Anaerobic Exercise (ALPE) Diagnosed with MRI Diffusion-weighted Imaging

A Case of Acute Renal Failure with Severe Loin Pain and Patchy Renal Ischemia after Anaerobic Exercise (ALPE) Diagnosed with MRI Diffusion-weighted Imaging

The value of MRI plain scan and DWI in the diagnosis of brain metastases

Objective: To investigate the clinical value of magnetic resonance imaging (MRI) plain scan and diffusion weighted imaging (DWI) in the diagnosis of brain metastases. Methods: The MRI plain imaging findings of 105 cases with brain metastases and 103 cases without brain metastases confirmed by enhanced MRI examination and clinical diagnosis were retrospectively analyzed. The comparisons of plain MRI findings including T1 weighted image (T1WI), T2WI, T2/fluid attenuated inversion recovery (T2/FLAIR), DWI and apparent diffusion coefficient (ADC) values were made between brain metastases and non-brain metastases. Results: The numbers of hypo-intensity, iso-intensity, hyper-intensity and heterogeneous signal intensity of T1WI in the brain metastatic group were 54, 23, 9 and 19, respectively, while the numbers of hypo-intensity and iso-intensity in the non-brain metastatic group were 52 and 51, respectively, with statistically significant difference (P<0.001). The numbers of hypo-intensity, iso-intensity, hyper-intensity and heterogeneous signal intensity of T2WI in the brain metastatic group were 1, 9, 72 and 23, respectively, while the numbers of iso-intensity and hyper-intensity in the non-brain metastatic group were 11 and 92, respectively, with statistically significant difference (P<0.001). The numbers of hypo-intensity, hyper-intensity and heterogeneous signal intensity of DWI in the brain metastatic group were 4, 31 and 65, respectively, while the number of hyper-intensity in the non-brain metastatic group was 4 and others were iso-intensity, respectively, with statistically significant difference (P<0.001). The numbers of hypo-intensity, iso-intensity, hyper-intensity and heterogeneous signal intensity of T2WI/FLAIR in the brain metastatic group were 4, 5, 60 and 36, respectively, while all cases in the non-brain metastatic group were hyper-intensity, with statistically significant difference (P<0.001). The number of lesion accompanied with peripheral edema in the brain metastatic group were 69 cases, significantly higher than 0 cases in the non-brain metastatic group (P<0.001). The mean ADC value in the brain metastatic group were (0.919±0.019)×10(-3) mm(2)/s, significantly lower than (1.098±0.012)×10(-3) mm(2)/s of non-brain metastatic group (P<0.05). Conclusions: For patients with a history of primary malignancy, the MRI plain scan signals of T1WI, T2WI, T2WI/FLAIR and DWI are significantly different between brain metastatic tumor and non-metastatic tumor. The mixed signal, peripheral edema and the restriction of DWI diffusion indicate brain metastases. The combined application of the above parameters can improve the diagnostic efficacy of predicting brain metastases, and contrast enhancement MRI examination should be performed for the confirmation of diagnosis.

Imaging diagnosis and legal implications of brain injury in survivors following single intrauterine fetal demise from monochorionic twins- a review of the literature.

Brain injury of the surviving twin from monochorionic pregnancies following intrauterine fetal demise during the second and third trimesters is a rare but severe complication. Monochorionicity and gestational age at the time of stillbirth seem to be decisive factors in terms of long-term neurologic outcome prediction for the survivor. Magnetic resonance imaging (MRI), diffusion weighted imaging (DWI) in particular, seem to bring the earliest and most accurate diagnosis. Ultrasound detection of brain damage is possible in later stages of fetal brain injury. It is essential to provide early diagnosis and multidisciplinary counsel to the parents to ensure informed decision making. For couples who choose to terminate pregnancy legislation related to late abortion might lead to further distress. Our paper aims to stress the importance of MRI DWI in the evaluation of surviving twins following single intrauterine fetal demise in monochorionic pregnancies and the delicate context of the medical professionals and parents facing this clinical situation, sometimes complicated by legal constraints.

The diagnostic utility of diffusion weighted MRI imaging and ADC ratio to distinguish benign from malignant renal masses: sorting the kittens from the tigers

BackgroundMRI is playing an increasing role in risk stratification and non-invasive diagnosis of the undifferentiated small renal mass. This study was designed to assess the reliability of MRI in diagnostic evaluation of renal masses, specifically characterising lesions with diffusion weighted imaging (DWI) and apparent diffusion coefficient (ADC) values.MethodsThis is a retrospective analysis of patients undergoing MRI as part of their clinical workup for a renal mass suspicious for renal cell carcinoma (RCC) on CT or ultrasound followed by biopsy and/or surgical excision. All cases were conducted on 3 Tesla MRI, with conventional breath-held sequences, DWI and dynamic contrast enhanced phases. Tumour regions of interest were evaluated on ADC maps and compared with T2 weighted and post-contrast images.ResultsOf the 66 renal tumours included, 33 (50.0%) were Clear Cell RCC, 11 (16.7%) were Oncocytoma, nine (13.6%) were Angiomyolipoma (AML), nine (13.6%) were Papillary RCC and four (6.1%) were Chromophobe RCC. Oncocytoma had the largest ADC values, significantly larger than AMLs and all RCC subtypes (p < 0.001). The average ADC value was also significantly larger in Clear Cell RCCs compared to AMLs, and other RCC subtypes (p < 0.001).ConclusionsMRI with DWI/ADC imaging may aid the differentiation of oncocytomas from RCCs and stratify RCC subtypes, Further studies are required to validate these findings.Trial registration: Not applicable/retrospective study.

The application of magnetic resonance imaging and diffusion-weighted imaging in the diagnosis of hypoxic-ischemic encephalopathy and kernicterus in premature infants.

BackgroundTo explore the application of magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) in the diagnosis of hypoxic-ischemic encephalopathy and kernicterus in premature infants.MethodsFifty-eight premature infants with hypoxic-ischemic encephalopathy and fifty-eight premature infants with kernicterus who were examined and treated in our hospital between January 2018 and January 2021 were assigned to the observation group or the control group. All patients were examined by MRI imaging and DWI imaging, and the examination results were compared between the two groups.ResultsNo significant differences were found in sensitivity, specificity, positive predictive value, or negative predictive value between the observation group and the control group (P>0.05). MRI could clearly visualize the signal changes of patients, whereas DWI did not show any signal changes. There was no significant difference between MRI and DWI in the diagnosis of hypoxic-ischemic encephalopathy in premature infants. Further, there was no significant difference in the diagnostic performance of MRI between the observation group and the control group (P>0.05). However, the diagnostic performance of DWI in the control group was better than that in the observation group, and the difference was statistically significant (P<0.05).ConclusionsMRI and DWI imaging have high detection rates for the diagnosis of hypoxic-ischemic encephalopathy and kernicterus in premature infants. These imaging methods can benefit the treatment of premature infants and have important clinical application value.

Diagnostic Accuracy of Quantitative Imaging Biomarkers in the Differentiation of Benign and Malignant Vertebral Lesions

PurposeTo compare and combine the diagnostic performance of the apparent diffusion coefficient (ADC) derived from diffusion-weighted imaging (DWI) and proton density fat fraction (PDFF) derived from chemical-shift encoding (CSE)-based water-fat magnetic resonance imaging (MRI) for distinguishing benign and malignant vertebral bone marrow lesions (VBML).MethodsA total of 55 consecutive patients with 53 benign (traumatic, inflammatory and primary) and 36 malignant (metastatic and hematologic) previously untreated VBMLs were prospectively enrolled in this IRB-approved study and underwent sagittal DWI (single-shot spin-echo echo-planar with multi-slice short TI inversion recovery fat suppression) and CSE-based MRI (gradient-echo 6‑point modified Dixon) in addition to routine clinical spine MRI at 1.5 T or 3.0 T. Diagnostic reference standard was established according to histopathology or imaging follow-up. The ADC = ADC (0, 800) and PDFF = fat / (water + fat) were calculated voxel-wise and examined for differences between benign and malignant lesions.ResultsThe ADC and PDFF values of malignant lesions were significantly lower compared to benign lesions (mean ADC 861 × 10−6 mm2/s vs. 1323 × 10−6 mm2/s, p < 0.001; mean PDFF 3.1% vs. 28.2%, p < 0.001). The areas under the curve (AUC) and diagnostic accuracies were 0.847 (p < 0.001) and 85.4% (cut-off at 1084.4 × 10−6 mm2/s) for ADC and 0.940 (p < 0.001) and 89.9% for PDFF (cut-off at 7.8%), respectively. The combined use of ADC and PDFF improved the diagnostic accuracy to 96.6% (malignancy if ADC ≤ 1118.2 × 10−6 mm2/s and PDFF ≤ 20.0%, otherwise benign).ConclusionQuantitative evaluation of both ADC and PDFF was useful in differentiating benign VBMLs from malignancy. The combination of ADC and PDFF improved the diagnostic performance and yielded high diagnostic accuracy for the differentiation of benign and malignant VBMLs.

MRI Diffusion-Weighted Imaging to Measure Infarct Volume: Assessment of Manual Segmentation Variability.

Manual segmentation of infarct volume on follow-up MRI diffusion-weighted imaging (MRI-DWI) is considered the gold standard but is prone torater variability. We assess the variability of manual segmentations of MRI-DWI infarct volume. Consecutive patients (May 2018 to May 2019) with the anterior circulation stroke and endovascularly treated were enrolled. All patients underwent 24- to 32-hour follow-up MRI. Three users manually segmented DWI infarct volumes slice by slice twice. The reference standard of DWI infarct volume was generated by the STAPLE algorithm. Intra- and interrater reliability was evaluated using the intraclass correlation coefficient (ICC) by comparing manual segmentations with the reference standard. Spatial measurements were evaluated using metrics of the Dice similarity coefficient (DSC). Volumetric measurements were compared using the lesion volume. The dataset consisted of 44 patients, mean (SD) age was 70.1 years (±10.3), 43% were women, and median baseline NIHSS score was 16. Among three users, the mean DSC for MRI-DWI infarct volume segmentations ranged from 80.6%±11.7% to 88.6%±7.5%, and the mean absolute volume difference was 2.8±6.8 to 13.0±14.0 ml. Interrater ICC among the users for DSC and infarct volume was .86 (95% confidence interval [95% CI]: .78-.91) and .997 (95% CI: .995-.998). Intrarater ICC for the three users was .83 (95% CI: .69-.93), .84 (95% CI: .72-.91), and .80 (95% CI: .64-.89) for DSC, and .99 (95% CI: .987-.996), .991 (95% CI: .983-.995), and .996 (95% CI: .993-.998) for infarct volume. Manual segmentation of infarct volume on follow-up MRI-DWI shows excellent agreement and good spatial overlap with the reference standard, suggesting its usefulness for measuring infarct volume on 24- to 32-hour MRI-DWI.

Value of bowel preparation techniques for prostate MRI: a preliminary study

BackgroundBowel preparation before multiparametric MRI (mpMRI) of the prostate is performed widely, despite contradictory or no evidence for efficacy.PurposeTo investigate the value of hyoscine N-butylbromide (HBB), microenema (ME) and ‘dietary restrictions’ (DR) for artifact reduction and image quality (IQ) in mpMRI of the prostate.Study typeRetrospective.PopulationBetween 10/2018 and 02/2020 treatment-naïve men (median age, 64.9; range 39.8–87.3) who underwent mpMRI of the prostate were included. The total patient sample comprised of n = 180 patients, who received either HBB, ME, were instructed to adhere to DR, or received a combination of those measures prior to the MR scan.Field strength/sequenceT2-weighted imaging (T2w), diffusion-weighted imaging (DWI), and dynamic contrast-enhanced MRI (DCE-MRI) scanned on two 3T systems.AssessmentA radiologist specialized in urogenital imaging (R1) and a senior radiology resident (R2) visually assessed IQ parameters on transversal T2w, DWI and ADC maps on a 5-point Likert-like scale.Statistical testsGroup comparison between IQ parameters was performed on reader level using Kruskal–Wallis and Mann–Whitney U tests. Binary univariate logistic regression analysis was used to assess independent predictors of IQ. Interrater agreement was assessed using Intraclass Correlation Coefficient (ICC).Results‘DWI geometric distortion’ was significantly more pronounced in the HBB+/ME−/DR− (R1, 3.6 and R2, 4.0) as compared to the HBB−/ME+/DR− (R1, 4.2 and R2, 4.6) and HBB+/ME+/DR− (R1, 4.3 and R2, 4.7) cohort, respectively. Parameters ‘DWI IQ’ and ‘Whole MRI IQ’ were rated similarly by both readers. ME was a significant independent predictor of ‘good IQ’ for the whole MRI for R1 [b = 1.09, OR 2.98 (95% CI 1.29, 6.87)] and R2 [b = 1.01, OR 2.73 (95% CI 1.24, 6.04)], respectively.Data conclusionME seems to significantly improve image quality of DWI and the whole mpMRI image set of the prostate. HBB and DR did not have any benefit.

Semi-Automated Segmentation of Bone Metastases from Whole-Body MRI: Reproducibility of Apparent Diffusion Coefficient Measurements.

Using semi-automated software simplifies quantitative analysis of the visible burden of disease on whole-body MRI diffusion-weighted images. To establish the intra- and inter-observer reproducibility of apparent diffusion coefficient (ADC) measures, we retrospectively analyzed data from 20 patients with bone metastases from breast (BCa; n = 10; aged 62.3 ± 14.8) or prostate cancer (PCa; n = 10; aged 67.4 ± 9.0) who had undergone examinations at two timepoints, before and after hormone-therapy. Four independent observers processed all images twice, first segmenting the entire skeleton on diffusion-weighted images, and then isolating bone metastases via ADC histogram thresholding (ADC: 650–1400 µm2/s). Dice Similarity, Bland-Altman method, and Intraclass Correlation Coefficient were used to assess reproducibility. Inter-observer Dice similarity was moderate (0.71) for women with BCa and poor (0.40) for men with PCa. Nonetheless, the limits of agreement of the mean ADC were just ±6% for women with BCa and ±10% for men with PCa (mean ADCs: 941 and 999 µm2/s, respectively). Inter-observer Intraclass Correlation Coefficients of the ADC histogram parameters were consistently greater in women with BCa than in men with PCa. While scope remains for improving consistency of the volume segmented, the observer-dependent variability measured in this study was appropriate to distinguish the clinically meaningful changes of ADC observed in patients responding to therapy, as changes of at least 25% are of interest.

Neurite orientation dispersion and density imaging parameters may help for the evaluation of epileptogenic tubers in tuberous sclerosis complex patients.

To investigate the usefulness of neurite orientation dispersion and density imaging (NODDI) in evaluating cortical tubers, especially epileptogenic tubers in tuberous sclerosis complex (TSC) patients. High-resolution conventional MRI and multi-shell diffusion-weighted imaging were performed in 27 TSC patients. Diffusion images were fitted to NODDI and DTI models. Tubers were visually assessed on different image types and scored by two neuroradiologists. For 10 patients who underwent epilepsy surgery, the contrast ratios between lesion and background tissue were measured on different image types, and these were compared between 16 epileptogenic tubers and 92 non-epileptogenic tubers. There were significant differences in lesion conspicuity scores and lesion-background contrast ratios across different sequences (both p< 0.001). The post hoc analysis showed that both the conspicuity scores and contrast ratios of intracellular volume fraction (ICVF) derived from NODDI were higher than other image types. For the 16 epileptogenic tubers, lesion visibility on ICVF was better/equal in 4/12 tubers compared with conventional MRI and better/equal in 5/11 tubers compared with DTI. Significant differences were observed between epileptogenic and non-epileptogenic tubers on diffusion maps, especially on orientation dispersion index derived from NODDI (p< 0.0001). ICVF demonstrated higher contrast than conventional MRI and DTI, which helped detection of subtle epileptogenic tubers. Moreover, NODDI parameters showed the potential to identify epileptogenicity. • The noninvasive localization of epileptogenic cortical tubers is essential for the preparation of epilepsy surgery for TSC patients. • ICVF derived from NODDI showed greater contrast than conventional MRI and DTI in detecting tubers, especially subtle epileptogenic ones. • Diffusion parameters, especially ODI derived from NODDI, can support the identification of epileptogenicity.

Prognostic Value of a Structural Brain MRI Score in the Acute Phase of Aneurysmal Subarachnoid Hemorrhage: A Pilot Study

Aneurysmal subarachnoid hemorrhage (aSAH) is associated with high morbidity and mortality despite advances in management. We evaluated the prognostic significance of a qualitative score using brain magnetic resonance imaging (MRI) features obtained early after aSAH. Patients with aSAH were enrolled in a prospective observational cohort and underwent brain MRI during their acute hospitalization. MRIs were rated using a scoring system that considers the anatomical location of signal intensity changes on diffusion-weighted imaging (DWI) and fluid-attenuated inversion recovery (FLAIR) sequences. The relationship between MRI scores and functional outcome defined by modified Rankin scale (mRS) at 6months was evaluated in uni- and multivariable models. The cohort included 45 aSAH patients (median World Federation of Neurologic Surgeons (IQR) 2 (1-4)) who underwent brain MRI a mean (SD) of 9.0 ± 8.0days after aSAH. At 6months after aSAH, 26 patients had achieved a favorable outcome (mRS ≤ 2) while 15 had an unfavorable outcome (mRS > 2). Deep gray nuclei (DGN) score (p = 0.016), cortex + DGN score (p = 0.015), FLAIR score (p = 0.016), DWI score (p = 0.0045), and overall score (p = 0.0081) were significantly lower in patients with favorable outcome compared to those with unfavorable outcome. However, MRI scores were not independent predictors of outcome in multivariable models adjusting for admission Hunt and Hess, Glasgow Coma Scale, or World Federation of Neurologic Surgeons scales. In this pilot study, a qualitative scoring system using anatomically defined MRI FLAIR and DWI signal abnormalities identified in the acute phase of aSAH was linked to 6-month functional outcome. However, these scores did not add prognostic value to established indices of neurological severity.

Abstract P354: SWAN-DWI Mismatch Predicts Clinical Outcome After Mechanical Thrombectomy

Objectives: Asymmetrically prominent veins on magnetic susceptibility sequences are thought to reflect the ischemic penumbra, by detecting high levels of desoxyheglobin. We investigated the relation between star-weighted angiography (SWAN)-diffusion weighted imaging (DWI) mismatch and clinical outcome after mechanical thrombectomy. Methods: We performed a retrospective study on patients who experienced anterior circulation stroke and for whom 1.5-Tesla MRI DWI and SWAN were performed upstream of mechanical thrombectomy. Mismatch was determined by using the Alberta Stroke Program Early CT Score (ASPECTS) on the diffusion-weighted and SWAN sequences. Three subgroups were defined in terms of mismatch level: high mismatch (HM), moderate mismatch (MM) and low mismatch (LM). Favorable outcome was defined as a modified Rankin score of 0-2 at three months. Multivariate logistic regression was used to examine associations between mismatch profiles and favorable outcomes. Results: The study included 108 patients who underwent mechanical thrombectomy. High mismatch was significantly associated with favorable clinical outcome (67% in the HM subgroup vs. 51% and 28% in the MM and LM subgroups respectively; odds ratio 1.25; 95 CI 1.02-1.56; p=0.037). No significant associations between SWAN-DWI mismatch and severe hemorrhagic complications or recanalization quality were brought to light by the present study. Conclusion: SWAN-DWI mismatch is a competent predictor of clinical outcome following mechanical thrombectomy.

Abstract P570: Arterial Stenosis in Posterior Reversible Encephalopathy Syndrome

Objectives: Posterior Reversible Encephalopathy Syndrome (PRES) is characterized as reversible vasogenic cerebral edema in a posterior-dominant distribution. Some patients with PRES have diffusion-weighted imaging (DWI) changes on MRI, as well as transient arterial stenosis. We examined the association between arterial stenosis and presence of hemorrhage and MRI-DWI changes in PRES. Methods: We retrospectively identified patients with PRES in electronic health records at a single health system from January 2008 to December 2018. We included patients age 18 years or older with clinical and radiographic evidence of PRES and arterial imaging (CT or MR angiography or digital subtraction angiogram). Any arterial stenosis was noted, with reversibility determined by repeat imaging. Patient characteristics, disease presentation, hospital lengths of stay and discharge dispositions, as well as imaging findings were collected and statistical analysis was used. Results: Of 281 patients with PRES, 169 had arterial imaging. Thirty-two (18.9%) had arterial stenosis and 60% had resolved arterial stenosis on follow-up imaging. Patients with arterial stenosis were younger compared to those without (47 v 55 years, p =0.03), however they did not differ in symptoms of presentation or comorbid conditions. Of note, arterial stenosis was associated with intracerebral hemorrhage[34% with stenosis and 18% without stenosis, p=0.05). However, the presence of MRI DWI lesions did not correlate with arterial stenosis [14/32 (44%) with stenosis, 49/137 (36%) without stenosis, p=0.42]. Among 97 patients with follow-up MRI, the presence of arterial stenosis was not associated with greater FLAIR reversibility. Furthermore, hospital length of stay or discharge disposition was not associated with arterial stenosis in PRES. Conclusions: Arterial stenoses are found in 19% of PRES patients, and most are reversed on follow-up imaging. They are also associated with hemorrhagic PRES, but not with MRI-DWI lesions or degree of FLAIR reversibility.

Comparison of MRI and CT for the Prediction of Microvascular Invasion in Solitary Hepatocellular Carcinoma Based on a Non-Radiomics and Radiomics Method: Which Imaging Modality Is Better?

Computed tomography (CT) and magnetic resonance imaging (MRI) are both capable of predicting microvascular invasion (MVI) in hepatocellular carcinoma (HCC). However, which modality is better is unknown. To intraindividually compare CT and MRI for predicting MVI in solitary HCC and investigate the added value of radiomics analyses. Retrospective. Included were 402 consecutive patients with HCC (training set:validation set=300:102). T2-weighted, diffusion-weighted, and contrast-enhanced T1-weighted imaging MRI at 3.0T and contrast-enhanced CT. CT- and MR-based radiomics signatures (RS) were constructed using the least absolute shrinkage and selection operator regression. CT- and MR-based radiologic (R) and radiologic-radiomics (RR) models were developed by univariate and multivariate logistic regression. The performance of the RS/models was compared between two modalities. To investigate the added value of RS, the performance of the R models was compared with the RR models in HCC of all sizes and 2-5 cm in size. Model performance was quantified by the area under the receiver operating characteristic curve (AUC) and compared using the Delong test. Histopathologic MVI was identified in 161 patients (training set:validation set=130:31). MRI-based RS/models tended to have a marginally higher AUC than CT-based RS/models (AUCs of CT vs. MRI, P: RS, 0.801 vs. 0.804, 0.96; R model, 0.809 vs. 0.832, 0.09; RR model, 0.835 vs. 0.872, 0.54). The improvement of RR models over R models in all sizes was not significant (P=0.21 at CT and 0.09 at MRI), whereas the improvement in 2-5 cm was significant at MRI (P < 0.05) but not at CT (P=0.16). CT and MRI had a comparable predictive performance for MVI in solitary HCC. The RS of MRI only had significant added value for predicting MVI in HCC of 2-5 cm. 3 TECHNICAL EFFICACY: Stage 2.