Post-contrast Sequences Research Articles

Hepatic T1 Mapping as a Novel Cardio-Hepatic Axis Imaging Biomarker Early after STEMI.

The hepatic response after ST-elevation myocardial infarction (STEMI) may be associated with mortality and morbidity. We aimed to assess the cardio-hepatic axis post-STEMI using cardiovascular magnetic resonance (CMR). This prospective, observational, single-centre study included consecutive STEMI patients who underwent CMR after primary angioplasty from January 2015 to January 2019. Standard infarct characteristics were analysed, and hepatic T1 and hepatic extracellular volume (ECV) were assessed using pre- and post-contrast T1-mapping sequences. The primary endpoint was the relationship between native hepatic T1-values and ischemic right ventricular (RV) involvement, determined by RV ejection fraction (EF) dysfunction and/or the presence of RV acute myocardial infarction (AMI). The diagnostic performance of hepatic T1 values for detecting RV involvement was assessed using the area under the receiver operating characteristic curve (AUC). Of 177 consecutive STEMI patients undergoing CMR, 142 were included. Patients with RV ischemic involvement, compared to those without, had significantly higher native hepatic T1 (p < 0.001) and hepatic ECV (p = 0.016). Hepatic T1 values demonstrated a good diagnostic performance in detecting RV involvement (AUC 0.826, p < 0.001) and correlated positively with NT-proBNP values (r = 0.754, p < 0.001). Patients with high hepatic T1 values (>605 ms) had significantly higher NT-proBNP levels (<0.001), larger RV end-diastolic volume (p < 0.001), lower RV-EF (p < 0.001), and a higher prevalence of RV AMI (p = 0.022) compared to those with hepatic T1 ≤ 605 ms, while left ventricular EF and infarct size were similar. Multivariable logistic regression analysis identified RV-EF (p = 0.010) and NT-proBNP values (p < 0.001) as independent predictors of increased hepatic T1 values. Patients with increased hepatic T1 values had a higher rate of re-hospitalization for heart failure at 17-month follow-up (12.1% vs 2.0%, p = 0.046). Hepatic T1 mapping has emerged as a possible novel imaging biomarker of the cardio-hepatic axis in STEMI, being associated with RV involvement and increased NT-proBNP values.

A multimodal neural network with gradient blending improves predictions of survival and metastasis in sarcoma

The objective of this study is to develop a multimodal neural network (MMNN) model that analyzes clinical variables and MRI images of a soft tissue sarcoma (STS) patient, to predict overall survival and risk of distant metastases. We compare the performance of this MMNN to models based on clinical variables alone, radiomics models, and an unimodal neural network. We include patients aged 18 or older with biopsy-proven STS who underwent primary resection between January 1st, 2005, and December 31st, 2020 with complete outcome data and a pre-treatment MRI with both a T1 post-contrast sequence and a T2 fat-sat sequence available. A total of 9380 MRI slices containing sarcomas from 287 patients are available. Our MMNN accepts the entire 3D sarcoma volume from T1 and T2 MRIs and clinical variables. Gradient blending allows the clinical and image sub-networks to optimally converge without overfitting. Heat maps were generated to visualize the salient image features. Our MMNN outperformed all other models in predicting overall survival and the risk of distant metastases. The C-Index of our MMNN for overall survival is 0.77 and the C-Index for risk of distant metastases is 0.70. The provided heat maps demonstrate areas of sarcomas deemed most salient for predictions. Our multimodal neural network with gradient blending improves predictions of overall survival and risk of distant metastases in patients with soft tissue sarcoma. Future work enabling accurate subtype-specific predictions will likely utilize similar end-to-end multimodal neural network architecture and require prospective curation of high-quality data, the inclusion of genomic data, and the involvement of multiple centers through federated learning.

Magnetic resonance imaging findings of plantar venous thrombosis: a comparative study with Doppler ultrasound

Objective: Analyze magnetic resonance imaging (MRI) findings, demographics and clinical data in patients with plantar venousthrombosis (PVT). Methods: A retrospective study screening patients with PVT, diagnosed with color Doppler ultrasound, who also underwent MRI of the foot and ankle. In the post-contrast MRI sequences, the intravascular filling defect was analyzed, and in the non-contrast MRI sequences, the diameter of the foot vessels was analyzed, and perivascular edema was documented. MRI exams from a control group without PVT were also analyzed. Results: Sixty-one cases and 204 controls were included. The lateral plantar veins were the most frequent location in the foot with PVT (63.9%). In all post-contrast sequences, an intravascular filling was seen. In the case group, veins had a significantly greater diameter compared to controls (p &lt; 0.05), and perivascular edema was observed in all cases (100%). A history of trauma/mechanical overload of the foot was documented in 83% of the patients (p &lt; 0.001). Conclusion: Our results showed that the lateral plantar vein was the most frequent location of PVT. An intravascular filling defect on post-contrast MRI sequences was seen in all PVT cases. Compared to the control group, all vessels had a greater diameter in the case group, and perivascular edema was observed in all cases. Our results also suggest that a clinical history of trauma or mechanical overload (physical activities) in the foot and ankle may be one of the causal factors of this pathology. Level of evidence III; Therapeutic studies - investigating the results of treatment; Retrospective comparative study

Volumetric Changes in the Choroid Plexus Associated with Spontaneous Intracranial Hypotension in Patients with Spinal CSF Leak.

The choroid plexus contains specialized ependymal cells responsible for CSF production. Recent studies have demonstrated volumetric and perfusion changes in the choroid plexus with age and neurodegenerative disorders, however, volumetric changes in the choroid plexus in low pressure states is not known. The purpose of this study is to evaluate volumetric differences in choroid plexus size in patients with spontaneous intracranial hypotension (SIH) resultant from spinal CSF leaks compared with healthy controls. This was a retrospective, institutional review board-approved study. Patients with MRI evidence of SIH and a spinal CSF leak diagnosed on myelography and subsequently confirmed at surgery were included in this study. All patients included in this study including age-matched healthy controls had a brain MRI performed on a either a 1.5 or 3T scanner with acquisition of 3D T1 postcontrast (eg, BRAVO, MPRAGE, etc). In all patients, the trigonum ventriculi volume, in the atria of the lateral ventricles, was contoured by using Visage-7 segmentation tools on the volumetric postcontrast T1 sequence. A basic 2-tailed t test was used to compare choroid plexus volumes between the 2 groups. Thirty-four patients were included with 17 patients with SIH with spinal CSF leak and 17 healthy control patients who were age- and sex-matched. The mean age of patients was 45 years, standard deviation 14 years. The mean volume of the choroid plexus for patients with SIH with spinal CSF leak was 1.2 cm3 (standard deviation = 0.26) compared with 0.63 cm3 (standard deviation = 0.31) in the control group (P < .0001). Results of this study demonstrate a higher choroid plexus volume in patients with SIH with spinal CSF leak compared with age- and sex-matched healthy controls. This likely reflects compensatory mechanisms to counteract intracranial hypotension by increasing CSF production as well as increased vascularity of the choroid plexus through expansion of the intracranial blood pool.

Arterial Spin-Labeling MR Imaging in the Detection of Intracranial Arteriovenous Malformations in Patients with Hereditary Hemorrhagic Telangiectasia.

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant disease that causes vascular malformations in a variety of organs and tissues, including brain AVMs. Because brain AVMs have the potential to cause disabling or fatal intracranial hemorrhage, detection of these lesions before rupture is the goal of screening MR imaging/MRA examinations in patients with HHT. Prior studies have demonstrated superior sensitivity for HHT-related brain AVMs by using postcontrast MR imaging sequences as compared with MRA alone. We now present data regarding the incremental benefit of including arterial spin-labeling (ASL) perfusion sequences as part of MR imaging/MRA screening in patients with this condition. We retrospectively analyzed 831 patients at the UCSF Hereditary Hemorrhagic Telangiectasia Center of Excellence. Of these, 42 patients had complete MR imaging/MRA, ASL perfusion scans, and criterion-standard DSA data. Two neuroradiologists reviewed imaging studies and a third provided adjudication when needed. Eight patients had no brain AVMs detected on DSA. The remaining 34 patients had 57 brain AVMs on DSA. Of the 57 identified AVMs, 51 (89.5%) were detected on ASL and 43 (75.4%) were detected on conventional MR imaging/MRA sequences (P = .049), with 8 lesions detected on ASL perfusion but not on conventional MR imaging. ASL provides increased sensitivity for brain AVMs in patients with HHT. Inclusion of ASL should be considered as part of comprehensive MR imaging/MRA screening protocols for institutions taking care of patients with HHT.

Non-contrast magnetic resonance evaluation of active multiple sclerosis lesions: Emerging role of quantitative synthetic magnetic resonance imaging.

The current study aims to explore the utility of novel synthetic MRI-derived quantitative parameters including myelin-correlated volume (MyC) in identifying active MS lesions without injecting gadolinium contrast. 43 MS patients underwent institutional MS protocol including 3D FLAIR and post-contrast 3D T1VIBE sequence on a 1.5T MR Scanner in addition to synthetic MRI sequence. MS plaques were categorised into enhancing (C) and non-enhancing (N) lesions. They were also sub-categorised based on location into periventricular WM lesions (P), deep WM lesions (D), infratentorial lesions (I) and cortical-juxtacortical (C) lesions. ROIs were placed on Synthetic FLAIR images in MS lesions and quantitative parameters of R1, R2, PD and myelin-correlated volume (MyC) obtained. Sensitivity and specificity for various cut-off values to differentiate enhancing from non-enhancing multiple sclerosis lesions were calculated by performing ROC curve analysis and logistic regression analysis. Contrast enhancing lesions demonstrated significantly higher mean R1, R2 values and lower mean PD values in comparison to non-enhancing lesions (p < 0.05) but with limited specificity. Region-wise analysis revealed high AUC values for mean R1 and R2 at cortical-juxtacortical lesions (p < 0.001) followed by periventricular lesions (p < 0.003) for differentiating enhancing from non-enhancing lesions with no significant contribution from MyC and PD values. Synthetic MRI-derived quantitative parameters of mean R1, R2, MyC and PD hold value in differentiating contrast enhancing and non-enhancing MS lesions without administering gadolinium-based contrast agent. However, the current study did not achieve significant specificity for establishing the same.

DANTE-CAIPI Accelerated Contrast-Enhanced 3D T1: Deep learning-based image quality improvement for Vessel Wall MR.

Accelerated and blood-suppressed post-contrast 3D intracranial vessel wall MRI (IVW) enables high-resolution rapid scanning but is associated with low SNR. We hypothesized that a deep-learning (DL) denoising algorithm applied to accelerated, blood-suppressed post-contrast IVW can yield high-quality images with reduced artifacts and higher SNR in shorter scan times. Sixty-four consecutive patients underwent IVW, including conventional post-contrast 3D T1-sampling perfection with application-optimized contrasts by using different flip angle evolution (SPACE) and delay-alternating with nutation for tailored excitation (DANTE) blood-suppressed and CAIPIRINHIA-accelerated (CAIPI) 3D T1-weighted TSE post-contrast sequences (DANTE-CAIPI-SPACE). DANTE-CAIPI-SPACE acquisitions were then denoised using an unrolled deep convolutional network (DANTECAIPI-SPACE+DL). SPACE, DANTE-CAIPI-SPACE, and DANTE-CAIPI-SPACE+DL images were compared for overall image quality, SNR, severity of artifacts, arterial and venous suppression, and lesion assessment using 4-point or 5-point Likert scales. Quantitative evaluation of SNR and contrast-to-noise ratio (CNR) was performed. DANTE-CAIPI-SPACE+DL showed significantly reduced arterial (1 [1-1.75] vs. 3 [3-4], p<0.001) and venous flow artifacts (1 [1-2] vs. 3 [3-4], p<0.001) compared to SPACE. There was no significant difference between DANTE-CAIPI-SPACE+DL and SPACE in terms of image quality, SNR, artifact ratings and lesion assessment. For SNR ratings, DANTE-CAIPI-SPACE+DL was significantly better compared to DANTE-CAIPI-SPACE (2 [1-2], vs. 3 [2-3], p<0.001). No statistically significant differences were found between DANTECAIPI-SPACE and DANTE-CAIPI-SPACE+DL for image quality, artifact, arterial blood and venous blood flow artifacts, and lesion assessment. Quantitative vessel wall SNR and CNR median values were significantly higher for DANTE-CAIPI-SPACE+DL (SNR: 9.71, CNR: 4.24) compared to DANTE-CAIPI-SPACE (SNR: 5.50, CNR: 2.64), (p<0.001 for each), but there was no significant difference between SPACE (SNR: 10.82, CNR: 5.21) and DANTE-CAIPI-SPACE+DL. Deep-learning denoised post-contrast T1-weighted DANTE-CAIPI-SPACE accelerated and blood-suppressed IVW showed improved flow suppression with a shorter scan time and equivalent qualitative and quantitative SNR measures relative to conventional post-contrast IVW. It also improved SNR metrics relative to post-contrast DANTE-CAIPI-SPACE IVW. Implementing deep-learning denoised DANTE-CAIPI-SPACE IVW has the potential to shorten protocol time while maintaining or improving the image quality of IVW. DL=deep learning; IVW=Intracranial vessel wall MRI; SPACE=sampling perfection with application-optimized contrasts by using different flip angle evolution; DANTE=delay-alternating with nutation for tailored excitation; CAIPI=controlled aliasing in parallel imaging; CNR=contrast-to-noise ratio.

Approaches to supratentorial brain tumours in children.

The differential diagnosis of supratentorial brain tumours in children can be challenging, especially considering the recent changes to the WHO classification of CNS tumours published in 2021. Many new tumour types have been proposed which frequently present in children and young adults and their imaging features are currently being described by the neuroradiology community.The purpose of this article is to provide guidance to residents and fellows new to the field of paediatric neuroradiology on how to evaluate an MRI of a patient with a newly diagnosed supratentorial tumour. Six different approaches are discussed including: 1. Tumour types, briefly discussing the main changes to the recent WHO classification of CNS tumours, 2. Patient age and its influence on incidence rates of specific tumour types, 3. Growth patterns, 4. Tumour location and how defining the correct location helps in narrowing down the differential diagnoses and 5. Imaging features of the tumour on DWI, SWI, FLAIR and post contrast sequences.

Cone beam computed tomography and cross-sectional anatomy of the region of the fetlock in the horse (Equus caballus).

This study aimed to delineate the detailed anatomy of the metacarpophalangeal (MCP) and metatarsophalangeal (MTP) joints in healthy horses using cone beam computed tomography (CBCT). The fetlock region of 15 cadaveric forelimbs and 14 cadaveric hindlimbs from nine adult horses without orthopaedic disease underwent CBCT scanning. Additionally, arthrography CBCT scans were conducted following intra-articular injection of a radiopaque contrast medium containing blue epoxy resin dye. Subsequently, limbs were frozen and sectioned to visualize anatomical structures in sectional planes corresponding to selected CBCT images. CBCT proved suitable for detailed visualization of the bony components of the fetlock region. Furthermore, the common digital extensor tendon, superficial and deep digital flexor tendons, suspensory ligament, and straight and oblique sesamoidean ligaments were identifiable on CBCT images. However, certain ligaments, such as the collateral sesamoidean ligaments and intersesamoidean ligaments, were not clearly identified. The hyaline cartilage of the MCP and MTP joint facets was assessable on the post-contrast sequence. In cases where a radiographic or ultrasound examination cannot provide a definitive diagnosis and determine the extent of disease, CBCT can provide additional valuable data on the equine MCP and MTP joint. The images obtained in this study can serve as a reference for CBCT examination of the equine MCP and MTP joint.

Deep Learning-Based Reconstruction of 3D T1 SPACE Vessel Wall Imaging Provides Improved Image Quality with Reduced Scan Times: A Preliminary Study.

Intracranial vessel wall imaging is technically challenging to implement, given the simultaneous requirements of high spatial resolution, excellent blood and CSF signal suppression, and clinically acceptable gradient times. Herein, we present our preliminary findings on the evaluation of a deep learning-optimized sequence using T1-weighted imaging. Clinical and optimized deep learning-based image reconstruction T1 3D Sampling Perfection with Application optimized Contrast using different flip angle Evolution (SPACE) were evaluated, comparing noncontrast sequences in 10 healthy controls and postcontrast sequences in 5 consecutive patients. Images were reviewed on a Likert-like scale by 4 fellowship-trained neuroradiologists. Scores (range, 1-4) were separately assigned for 11 vessel segments in terms of vessel wall and lumen delineation. Additionally, images were evaluated in terms of overall background noise, image sharpness, and homogeneous CSF signal. Segment-wise scores were compared using paired samples t tests. The scan time for the clinical and deep learning-based image reconstruction sequences were 7:26 minutes and 5:23 minutes respectively. Deep learning-based image reconstruction images showed consistently higher wall signal and lumen visualization scores, with the differences being statistically significant in most vessel segments on both pre- and postcontrast images. Deep learning-based image reconstruction had lower background noise, higher image sharpness, and uniform CSF signal. Depiction of intracranial pathologies was better or similar on the deep learning-based image reconstruction. Our preliminary findings suggest that deep learning-based image reconstruction-optimized intracranial vessel wall imaging sequences may be helpful in achieving shorter gradient times with improved vessel wall visualization and overall image quality. These improvements may help with wider adoption of intracranial vessel wall imaging in clinical practice and should be further validated on a larger cohort.

MDB-94. RADIOMICS-BASED DECISION SUPPORT FOR PEDIATRIC MEDULLOBLASTOMA RISK STRATIFICATION ON MULTI-PARAMETRIC MRI

Abstract BACKGROUND Medulloblastoma (MB) is the most common pediatric brain malignancy. Accurate risk stratification is crucial for prescribing appropriate therapy. However, current risk stratification into standard or high-risk groups is limited in scope and does not accurately address the unique biological behavior of each specific tumor, with approximately 30% of children diagnosed with MB suffering from treatment failure. We developed a radiomic tool to more accurately risk stratify children with MB. METHODS We collected 1.5T/3T MRI (Siemens, Philips, or GE scanners) and clinical data from 80 patients with MB treated at Children’s Healthcare of Atlanta. Radiomic features that quantify textural heterogeneity including first and second order statistics, Haralick’s features from Gray Level Co-occurrence Matrices, and CoLIAge were extracted from tumor volumes segmented by a board-certified radiologist from multi-parametric MRI data including Apparent Diffusion Coefficient (ADC), T2, and post-contrast T1 sequences. Continuous survival models were built using the Cox proportional hazard method with 70% of the data for progression free survival (PFS) and overall survival (OS) using the 5 most predictive features obtained by univariate analysis after removing correlated features within the training data. RESULTS We developed three models with T1, T2, and ADC separately to evaluate predictive power of radiomic signatures. Three models for predicting MB OS delivered Harrel’s concordance indices (C-index) of 0.72 and 0.61 (T1); 0.70 and 0.65 (T2); and 0.80 and 0.76 (ADC) for training and test, respectively. C-indices for PFS were 0.70 and 0.69 (T1); 0.73 and 0.67 (T2); and 0.63 and 0.61 (ADC). CONCLUSIONS Our preliminary results show the feasibility and efficacy of our approach for predicting MB OS and PFS. Future studies will build an integrated model combining T1,T2, ADC, and other clinical information for predicting MB OS and PFS using a large multi-center validation cohort.

Leptomeningeal enhancement in multiple sclerosis: a focus on patients treated with hematopoietic stem cell transplantation.

Leptomeningeal enhancement (LME) is considered an MRI marker of leptomeningeal inflammation in inflammatory neurological disorders, including multiple sclerosis (MS). To our knowledge, no disease-modifying therapies (DMTs) have been demonstrated to affect LME number or morphology so far. Monocentric study investigating the frequency and number of LME in a cohort of people with (pw)MS who performed a 3 T brain MRI with a standardized protocol (including a post-contrast FLAIR sequence), and exploring the impact of autologous hematopoietic stem cell transplantation (AHSCT) on this marker. In a longitudinal pilot study, consecutive MRIs were also analyzed in a subgroup of pwMS, including patients evaluated both pre- and post-AHSCT. Fifty-five pwMS were included: 24/55 (44%) had received AHSCT (AHSCT group) and 31 other treatments (CTRL group). At least one LME was identified in 19/55 (35%) cases (42 and 29% in the AHSCT and CTRL groups, respectively; p = 0.405). In the AHSCT group, LME number correlated with age at AHSCT (R = 0.50; p = 0.014), but not with age at post-treatment MRI. In the longitudinal pilot study (n = 8), one LME disappeared following AHSCT in 1/4 patients, whereas LME number was unchanged in the remaining four pwMS from the CTRL group. These results suggest that AHSCT may affect development and persistence of LME, strengthening the indication for early use of effective therapies bioavailable within the central nervous system (CNS), and therefore potentially targeting compartmentalized inflammation.

Predicting Response to Exclusive Combined Radio-Chemotherapy in Naso-Oropharyngeal Cancer: The Role of Texture Analysis.

The aim of this work is to identify MRI texture features able to predict the response to radio-chemotherapy (RT-CHT) in patients with naso-oropharyngeal carcinoma (NPC-OPC) before treatment in order to help clinical decision making. Textural features were derived from ADC maps and post-gadolinium T1-images on a single MRI machine for 37 patients with NPC-OPC. Patients were divided into two groups (responders/non-responders) according to results from MRI scans and 18F-FDG-PET/CT performed at follow-up 3-4 and 12 months after therapy and biopsy. Pre-RT-CHT lesions were segmented, and radiomic features were extracted. A non-parametric Mann-Whitney test was performed. A p-value < 0.05 was considered significant. Receiver operating characteristic curves and area-under-the-curve values were generated; a 95% confidence interval (CI) was reported. A radiomic model was constructed using the LASSO algorithm. After feature selection on MRI T1 post-contrast sequences, six features were statistically significant: gldm_DependenceEntropy and DependenceNonUniformity, glrlm_RunEntropy and RunLengthNonUniformity, and glszm_SizeZoneNonUniformity and ZoneEntropy, with significant cut-off values between responder and non-responder group. With the LASSO algorithm, the radiomic model showed an AUC of 0.89 and 95% CI: 0.78-0.99. In ADC, five features were selected with an AUC of 0.84 and 95% CI: 0.68-1. Texture analysis on post-gadolinium T1-images and ADC maps could potentially predict response to therapy in patients with NPC-OPC who will undergo exclusive treatment with RT-CHT, being, therefore, a useful tool in therapeutical-clinical decision making.

Transition of intracranial aneurysmal wall enhancement from high to low wall shear stress mediation with size increase: A hemodynamic study based on 7T magnetic resonance imaging

BackgroundWall shear stress (WSS) has been proved to be related to the formation, development and rupture of intracranial aneurysms. Aneurysm wall enhancement (AWE) on magnetic resonance imaging (MRI) can be caused by inflammation and have confirmed its relationship with low WSS. High WSS can also result in inflammation but the research of its correlation with AWE is lack because of the focus on large aneurysms limited by 3T MRI in most previous studies.This study aimed to assess the potential association between high or low WSS and AWE in different aneuryms. Especially the relationship between high WSS and AWE in small aneurysm. MethodsForty-three unruptured intracranial aneurysms in 42 patients were prospectively included for analysis. 7.0 T MRI was used for imaging. Aneurysm size was measured on three-dimensional time-of-flight (TOF) images. Aneurysm-to-pituitary stalk contrast ratio (CRstalk) was calculated on post-contrast black-blood T1-weighted fast spin echo sequence images. Hemodynamics were assessed by four-dimensional flow MRI. ResultsThe small aneurysms group had more positive WSS–CRstalk correlation coefficient distribution (dome: 78.6 %, p = 0.009; body: 50.0 %, p = 0.025), and large group had more negative coefficient distribution (dome: 44.8 %, p = 0.001; body: 69.0 %, p = 0.002). Aneurysm size was positively correlated with the significant OSI–CRstalk correlation coefficient at the dome (p = 0.012) and body (p = 0.010) but negatively correlated with the significant WSS–CRstalk correlation coefficient at the dome (p < 0.001) and body (p = 0.017). ConclusionAWE can be mediated by both high and low WSS, and translate from high WSS- to low WSS-mediated pathways as size increase. Additionally, AWE may serve as an indicator of the stage of aneurysm development via different correlations with hemodynamic factors.

Comparison between postcontrast thin-slice T1-weighted 2D spin echo and 3D T1-weighted SPACE sequences in the detection of brain metastases at 1.5 and 3 T

ObjectivesAccurate detection of metastatic brain lesions (MBL) is critical due to advances in radiosurgery. We compared the results of three readers in detecting MBL using T1-weighted 2D spin echo (SE) and sampling perfection with application-optimized contrasts using different flip angle evolution (SPACE) sequences with whole-brain coverage at both 1.5 T and 3 T.MethodsFifty-six patients evaluated for MBL were included and underwent a standard protocol (1.5 T, n = 37; 3 T, n = 19), including postcontrast T1-weighted SE and SPACE. The rating was performed by three raters in two sessions > six weeks apart. The true number of MBL was determined using all available imaging including follow-up. Intraclass correlations for intra-rater and inter-rater agreement were calculated. Signal intensity ratios (SIR; enhancing lesion, white matter) were determined on a subset of 46 MBL > 4 mm. A paired t-test was used to evaluate postcontrast sequence order and SIR. Reader accuracy was evaluated by the coefficient of determination.ResultsA total of 135 MBL were identified (mean/subject 2.41, SD 6.4). The intra-rater agreement was excellent for all 3 raters (ICC = 0.97–0.992), as was the inter-rater agreement (ICC = 0.995 SE, 0.99 SPACE). Subjective qualitative ratings were lower for SE images; however, signal intensity ratios were higher in SE sequences. Accuracy was high in all readers for both SE (R2 0.95–0.96) and SPACE (R2 0.91–0.96) sequences.ConclusionsAlthough SE sequences are superior to gradient echo sequences in the detection of small MBL, they have long acquisition times and frequent artifacts. We show that T1-weighted SPACE is not inferior to standard thin-slice SE sequences in the detection of MBL at both imaging fields.Critical relevance statementOur results show the suitability of 3D T1-weighted turbo spin echo (TSE) sequences (SPACE, CUBE, VISTA) in the detection of brain metastases at both 1.5 T and 3 T.Key points• Accurate detection of brain metastases is critical due to advances in radiosurgery.• T1-weighted SE sequences are superior to gradient echo in detecting small metastases.• T1-weighted 3D-TSE sequences may achieve high resolution and relative insensitivity to artifacts.• T1-weighted 3D-TSE sequences have been recommended in imaging brain metastases at 3 T.• We found T1-weighted 3D-TSE equivalent to thin-slice SE at 1.5 T and 3 T.Graphical

The effect of gadolinium-based intravenous contrast in the initial characterization of musculoskeletal soft tissue tumors

ObjectiveTo determine if gadolinium-based contrast agents increase the sensitivity, specificity or reader confidence of malignant potential in musculoskeletal soft tissue tumors. MethodsPre- and post-contrast MRI studies from 87 patients were read by three independent radiologists of different experience. Readers noted malignant potential and confidence in their diagnosis based on pre-contrast and post-contrast MRI studies. Statistical models assessed for agreement between MRI reader diagnosis and pathologic results as well as analyzing effects of contrast on reader confidence. Inter- and intra-observer variabilities of malignant potential were also calculated. Results87 patients (48 benign and 39 malignant; mean [± SD] age 51 ± 17.9 and 57.1 ± 17.1, respectively) were evaluated. For all readers, pre-contrast and post-contrast sensitivities were 68.1 % and 70.6 % while pre-contrast and post-contrast specificities were 84.6 % and 83.8 %, respectively without significant change (p=0.88). There was not a significant association with the use of contrast and prediction of malignant potential with or without the resident reader (p=0.65 and p=0.82). Use of contrast was significantly associated with higher levels of reader confidence (p=0.02) for all readers. Inter- and intra-observer variabilities were in good agreement (W = 0.77 and 0.70). ConclusionThe addition of a post-contrast sequence increased reader confidence in their diagnosis without a corresponding significant increase in accurate prediction of malignant potential.

7T MRI for Cushing Disease: A Single-Institution Experience and Literature Review.

Cushing disease is typically caused by a pituitary adenoma that frequently is small and challenging to detect on conventional MR imaging. High-field-strength 7T MR imaging can leverage increased SNR and contrast-to-noise ratios compared with lower-field-strength MR imaging to help identify small pituitary lesions. We aimed to describe our institutional experience with 7T MR imaging in patients with Cushing disease and perform a review of the literature. We performed a retrospective analysis of 7T MR imaging findings in patients with pathology-proved Cushing disease from a single institution, followed by a review of the literature on 7T MR imaging for Cushing disease. Our institutional experience identified Cushing adenomas in 10/13 (76.9%) patients on 7T; however, only 5/13 (38.5%) lesions were discrete. Overall, the imaging protocols used were heterogeneous in terms of contrast dose as well as type of postcontrast T1-weighted sequences (dynamic, 2D versus 3D, and type of 3D sequence). From our institutional data, specific postgadolinium T1-weighted sequences were helpful in identifying a surgical lesion as follows: dynamic contrast-enhanced, 2/7 (28.6%); 2D FSE, 4/8 (50%); 3D sampling perfection with application-optimized contrasts by using different flip angle evolution (SPACE), 5/6 (83.3%); and 3D MPRAGE, 8/11 (72.7%). The literature review identified Cushing adenomas in 31/33 (93.9%) patients on 7T. 7T MR imaging for pituitary lesion localization in Cushing disease is a new technique with imaging protocols that vary widely. Further comparative research is needed to identify the optimal imaging technique as well as assess the benefit of 7T over lower-field-strength MR imaging.

Comparing the Efficacy of a Combination of Diffusion-Weighted Imaging and T2-STIR (Short Tau Inversion Recovery) Imaging With Contrast-Enhanced MRI in the Evaluation of Perianal Fistula.

Perianal fistula is clinically diagnosed and commonly characterized using magnetic resonance imaging (MRI). Diffusion-weighted imaging (DWI) and T2-weighted imaging are emerging techniques that can obviate the need for contrast injection in cases where contrast administration is not feasible or contraindicated. The main objective of our study was to compare the efficacy of the combination of DWI and T2 STIR (short tau inversion recovery) imaging with contrast-enhanced MRI for the diagnosis and characterization of perianal fistula. Sixty-nine patients with clinical perianal fistula with at least one external opening were evaluated with DWI, T2 STIR, and contrast MRI. A comparative cross-sectional study was conducted in the Department of Radiodiagnosis and Imaging, All India Institute of Medical Sciences, Bhopal, India. The chi-square test was done to find the association between categorical variables. The Kappa test was done to estimate the agreement between two different tests in measuring the outcome. The validity of tests was measured using sensitivity, specificity, positive predictive value, negative predictive value, and accuracy. The combination of DWI and T2 STIR is equivalent to contrast-enhanced MRI in the evaluation of primary and complicated perianal fistula. The combination of DWI and T2 STIR is superior to DWI alone in the classification and characterization of perianal fistula. However, DWI is superior to T2 STIR in differentiating perianal inflammation with abscess from perianal inflammation without abscess and can be used as an alternative to post-contrast fat-suppressed T1-WI in the detection of perianal abscesses and disease activity. DWI can be used as an adjunct to T2 STIR, and the combination of DWI and T2 STIR can replace the post-contrast fat-suppressed T1 MRI sequence in the classification and characterization of perianal fistula.

Abstract 38: Temporal Changes in Intracranial Arterial Diseases: A Longitudinal High-Resolution Vessel Wall Imaging Analysis

Introduction: Temporal changes of intracranial arterial disease (ICAD) in patients with ischemic stroke in high-resolution vessel wall imaging (HR-VWI) have not been elucidated. Methods: We recruited consecutive ICAD-related ischemic stroke patients admitted between June 2016 and June 2019 and had subsequent HR-VWI follow-ups. On HR-VWI, we manually segmented the lumen area (LA), total vessel area (TVA), and enhancing area (EA) of the culprit lesion's most stenotic part in the perpendicular section on T1-weighted, proton density, and post-contrast T1-weighted sequences. We defined the area stenosis as [1-LA/TVA]х100 (%) and the enhancing proportion as EA/TVAх100 (%). Enhancement ratio of the enhancing lesion was also quantified. Three raters independently quantified the imaging using ITK-SNAP with acceptable inter-rater reliability. Results: A total of 208 patients (age 57±14, male 58%) with 469 HR-VWIs (2-6 scans per patient) were included. The causes of ICAD were atherosclerosis (69%), dissection (24%), vasculitis (3%), moyamoya disease (1%), and other causes (2%). The median follow-up duration was 9.0 months (interquartile range: 3.9-13.2 months), and the maximum follow-up duration was 41.3 months. Among patients with atherosclerosis, area stenosis aggravated, stable, and improved in 7%, 77%, and 16%, respectively, with an overall rate of 0.23 ± 0.07% improvement per month. Among patients with dissection, area stenosis aggravated, stable, and improved in 2%, 49%, and 49%, respectively, with an overall rate of 2.11 ± 0.26% improvement per month (Figure, P -for-difference &lt; 0.01). The temporal changes of the enhancing proportion and enhancement ratio were different between atherosclerosis and dissection (Figure, P &lt; 0.01). Conclusions: ICAD lesions had dynamic changes over time; the temporal changes of atherosclerosis and dissection are distinct. Serial HR-VWI can offer insights for a more accurate diagnosis of the underlying pathologies of ICADs.

Non-Invasive Tumor Grade Evaluation in Von Hippel-Lindau-Associated Clear Cell Renal Cell Carcinoma: A Magnetic Resonance Imaging-Based Study.

Pathology grading is an essential step for the treatment and evaluation of the prognosis in patients with clear cell renal cell carcinoma (ccRCC). To investigate the utility of texture analysis in evaluating Fuhrman grades of renal tumors in patients with Von Hippel-Lindau (VHL)-associated ccRCC, aiming to improve non-invasive diagnosis and personalized treatment. Retrospective analysis of a prospectively maintained cohort. One hundred and thirty-six patients, 84 (61%) males and 52 (39%) females with pathology-proven ccRCC with a mean age of 52.8 ± 12.7 from 2010 to 2023. 1.5 and 3 T MRIs. Segmentations were performed on the T1-weighted 3-minute delayed sequence and then registered on pre-contrast, T1-weighted arterial and venous sequences. A total of 404 lesions, 345 low-grade tumors, and 59 high-grade tumors were segmented using ITK-SNAP on a T1-weighted 3-minute delayed sequence of MRI. Radiomics features were extracted from pre-contrast, T1-weighted arterial, venous, and delayed post-contrast sequences. Preprocessing techniques were employed to address class imbalances. Features were then rescaled to normalize the numeric values. We developed a stacked model combining random forest and XGBoost to assess tumor grades using radiomics signatures. The model's performance was evaluated using positive predictive value (PPV), sensitivity, F1 score, area under the curve of receiver operating characteristic curve, and Matthews correlation coefficient. Using Monte Carlo technique, the average performance of 100 benchmarks of 85% train and 15% test was reported. The best model displayed an accuracy of 0.79. For low-grade tumor detection, a sensitivity of 0.79, a PPV of 0.95, and an F1 score of 0.86 were obtained. For high-grade tumor detection, a sensitivity of 0.78, PPV of 0.39, and F1 score of 0.52 were reported. Radiomics analysis shows promise in classifying pathology grades non-invasively for patients with VHL-associated ccRCC, potentially leading to better diagnosis and personalized treatment. 1 TECHNICAL EFFICACY: Stage 2.