Faculty Bibliography

Background: Despite studies suggesting that blacks may be at greater risk of developing AD, there have been few studies investigating health disparities, and blacks have been underrepresented in many prominent AD biomarker studies and clinical trials. The current ATN biomarker classification system may not fully account for health disparities and can't explain the increased prevalence among blacks for both AD and AD vascular risks of diabetes and hypertension when compared to whites. Research on cognitive aging has traditionally focused on how decline in various cortical and hippocampal (Hip) regions influences cognition. However, tau pathology emerges decades before amyloid pathology, appearing first in the brainstem (BS); particularly in the locus coeruleus (LC), the source of brain's norepinephrine (NE). Our decade-long studies in humans using a norepinephrine transporter (NET)-selective radiotracer ([11C]MRB) have demonstrated a special vulnerability of LC to aging and stress.
Method(s): Co-registration of PET (dynamic [11C]MRB), MRI and the FreeSurfer (FS) atlas images of each individual was used to generate regional time-activity curves using Firevoxel. Binding potential (BPND) values were determined using MRTM2 with occipital as the reference region. Annual percent change (APC) of BPND was calculated based on linear regression (APC = 100 x (em-1), m: slope) and effects of age, gender and ethnicity on tracer binding were evaluated.
Result(s): For all HC (N=31), with both genders and all races included, age-sensitive decline of NET availability was observed; e.g., 0.3-0.5%/yr for Hip, BS and olfactory. However, our data reveals that the decline rate of NET is much faster among blacks starting in the mid-30s, particularly in black males; e.g., 2-3%/yr vs. 0.14-0.23%/yr in thalamus and brainstem for black males vs. white males (p < 0.00001).
Conclusion(s): In addition to our previously determined age effect on MRB-NET binding, this report further reveals the role of ethnicity effects on NET availability. Our study showed that a faster decline of LC-NE function occurs in blacks, possibly caused by cumulative stress to socioeconomic disadvantage and racial discrimination and may be responsible for the different disease expression among blacks. Thus, NET availability imaging represents a novel biomarker approach to racial-dependent strategies for diagnosis and assessment of therapeutic interventions

ABSTRACT/UNASSIGNED:This study aimed to evaluate the effect of an artificial intelligence (AI) support system on breast ultrasound diagnostic accuracy.In this Health Insurance Portability and Accountability Act-compliant, institutional review board-approved retrospective study, 200 lesions (155 benign, 45 malignant) were randomly selected from consecutive ultrasound-guided biopsies (June 2017-January 2019). Two readers, blinded to clinical history and pathology, evaluated lesions with and without an Food and Drug Administration-approved AI software. Lesion features, Breast Imaging Reporting and Data System (BI-RADS) rating (1-5), reader confidence level (1-5), and AI BI-RADS equivalent (1-5) were recorded. Statistical analysis was performed for diagnostic accuracy, negative predictive value, positive predictive value (PPV), sensitivity, and specificity of reader versus AI BI-RADS. Generalized estimating equation analysis was used for reader versus AI accuracy regarding lesion features and AI impact on low-confidence score lesions. Artificial intelligence effect on false-positive biopsy rate was determined. Statistical tests were conducted at a 2-sided 5% significance level.There was no significant difference in accuracy (73 vs 69.8%), negative predictive value (100% vs 98.5%), PPV (45.5 vs 42.4%), sensitivity (100% vs 96.7%), and specificity (65.2 vs 61.9; P = 0.118-0.409) for AI versus pooled reader assessment. Artificial intelligence was more accurate than readers for irregular shape (74.1% vs 57.4%, P = 0.002) and less accurate for round shape (26.5% vs 50.0%, P = 0.049). Artificial intelligence improved diagnostic accuracy for reader-rated low-confidence lesions with increased PPV (24.7% AI vs 19.3%, P = 0.004) and specificity (57.8% vs 44.6%, P = 0.008).Artificial intelligence decision support aid may help improve sonographic diagnostic accuracy, particularly in cases with low reader confidence, thereby decreasing false-positives.

PURPOSE/OBJECTIVE:To assess the utility of a 2D dynamic HASTE sequence in assessment of cervical spine flexion-extension, specifically (1) comparing dynamic spondylolisthesis to radiographs and (2) assessing dynamic contact upon or deformity of the cord. METHODS:Patients with a dynamic flexion-extension sagittal 2D HASTE sequence in addition to routine cervical spine sequences were identified. Static and dynamic listhesis was first determined on flexion-extension radiographs reviewed in consensus. Blinded assessment of the dynamic HASTE sequence was independently performed by 2 radiologists for (1) listhesis and translation during flexion-extension and (2) dynamic spinal cord impingement (cord contact or deformity between neutral, flexion and extension). RESULTS:32 scans in 32 patients (9 males, 23 females) met inclusion criteria acquired on 1.5 T (n = 15) and 3 T (n = 17) scanners. The mean acquisition time was 51.8 s (range 20-95 seconds). Dynamic translation was seen in 14 patients on flexion-extension radiographs compared to 12 (reader 1) and 13 (reader 2) patients on HASTE, with 90.6 % agreement (K = 0.83; p = 0.789). In all cases dynamic listhesis was ≤3 mm translation with one patient showing dynamic listhesis in the range 4-6 mm. Four cases (13 %) demonstrated deformity of the cord between flexion-extension, not present in the neutral position. For cord impingement there was strong inter-reader agreement (K = 0.93) and the paired sample Wilcoxon signed rank test found no significant difference between the impingement scores of the two readers (p = 0.787). CONCLUSIONS:A sagittal dynamic flexion-extension HASTE sequence provides a rapid addition to standard MRI cervical spine protocols, which may useful for assessment of dynamic spondylolisthesis and cord deformity.

OBJECTIVES/OBJECTIVE:The primary objective was to compare the performance of 3 different abbreviated MRI (AMRI) sets extracted from a complete gadoxetate-enhanced MRI obtained for hepatocellular carcinoma (HCC) screening. Secondary objective was to perform a preliminary cost-effectiveness analysis, comparing each AMRI set to published ultrasound performance for HCC screening in the USA. METHODS:This retrospective study included 237 consecutive patients (M/F, 146/91; mean age, 58 years) with chronic liver disease who underwent a complete gadoxetate-enhanced MRI for HCC screening in 2017 in a single institution. Two radiologists independently reviewed 3 AMRI sets extracted from the complete exam: non-contrast (NC-AMRI: T2-weighted imaging (T2wi)+diffusion-weighted imaging (DWI)), dynamic-AMRI (Dyn-AMRI: T2wi+DWI+dynamic T1wi), and hepatobiliary phase AMRI (HBP-AMRI: T2wi+DWI+T1wi during the HBP). Each patient was classified as HCC-positive/HCC-negative based on the reference standard, which consisted in all available patient data. Diagnostic performance for HCC detection was compared between sets. Estimated set characteristics, including historical ultrasound data, were incorporated into a microsimulation model for cost-effectiveness analysis. RESULTS:The reference standard identified 13/237 patients with HCC (prevalence, 5.5%; mean size, 33.7 ± 30 mm). Pooled sensitivities were 61.5% for NC-AMRI (95% confidence intervals, 34.4-83%), 84.6% for Dyn-AMRI (60.8-95.1%), and 80.8% for HBP-AMRI (53.6-93.9%), without difference between sets (p range, 0.06-0.16). Pooled specificities were 95.5% (92.4-97.4%), 99.8% (98.4-100%), and 94.9% (91.6-96.9%), respectively, with a significant difference between Dyn-AMRI and the other sets (p < 0.01). All AMRI methods were effective compared with ultrasound, with life-year gain of 3-12 months against incremental costs of US$ < 12,000. CONCLUSIONS:NC-AMRI has limited sensitivity for HCC detection, while HBP-AMRI and Dyn-AMRI showed excellent sensitivity and specificity, the latter being slightly higher for Dyn-AMRI. Cost-effectiveness estimates showed that AMRI is effective compared with ultrasound. KEY POINTS/CONCLUSIONS:• Comparison of different abbreviated MRI (AMRI) sets reconstructed from a complete gadoxetate MRI demonstrated that non-contrast AMRI has low sensitivity (61.5%) compared with contrast-enhanced AMRI (80.8% for hepatobiliary phase AMRI and 84.6% for dynamic AMRI), with all sets having high specificity. • Non-contrast and hepatobiliary phase AMRI can be performed in less than 14 min (including set-up time), while dynamic AMRI can be performed in less than 17 min. • All AMRI sets were cost-effective for HCC screening in at-risk population in comparison with ultrasound.

We characterize the whole-brain N-acetyl-aspartate (WBNAA) and brain tissue fractions across the adult lifespan and test the hypothesis that, despite age-related atrophy, neuronal integrity (reflected by WBNAA) is preserved in normal aging. Two-hundred-and-seven participants: 133 cognitively intact older adults (73.6 ± 7.4 mean ± standard deviation, range: 60-90 year old) and 84 young (37.9 ± 11, range: 21-59 year old) were scanned with proton magnetic resonance spectroscopy and T₁-weighted MRI. Their WBNAA, fractional brain parenchyma, and gray and white matter volumes (fBPV, fGM, and fWM) were compared and modeled as functions of age and sex. Compared with young, older-adults' WBNAA was lower by ~35%, and fBPV, fGM and fWM were lower by ~10%. Linear regressions found 0.5%/year WBNAA and 0.2%/year fBPV and fGM declines, whereas fWM rose to age ~40 years, and declined thereafter. fBPV and fGM were 1.8% and 4% higher in women, with no sex decline rates difference. We conclude that contrary to our hypothesis, atrophy was accompanied by WBNAA decline. Across the entire age range, women's brains showed less atrophy than men's. Formulas to estimate WBNAA and brain tissue fractions in healthy adults are provided to help differentiate normal from abnormal aging.

PURPOSE/OBJECTIVE:To report the quality of gadoxetate disodium MRI in a large series by assessing the prevalence of: 1) arterial phase (AP) artifacts and its predictive factors, 2) decreased hepatic contrast uptake during the hepatobiliary phase (HBP). METHODS:This retrospective single center study included 851 patients (M/F:537/314, mean age: 63y) with gadoxetate disodium MRI. The MRI protocol included unenhanced, dual arterial [early and late arterial phases (AP)], portal venous, transitional and hepatobiliary phases. Three radiologists graded dynamic images using a 5-scale score (1: no motion, 5: severe, nondiagnostic) for assessment of transient severe motion (TSM, defined as a score ≥4 during at least one AP with a score ≤3 during other phases). HBP uptake was assessed using a 3-scale score (based on portal vein/hepatic signal). The association between demographic, clinical and acquisition parameters with TSM was tested in uni- and multivariate logistic regression. RESULTS:TSM was observed in 103/851 patients (12.1 %): 83 (9.8 %) in one AP and 20 (2.3 %) in both APs. A score of 5 (nondiagnostic) was assigned in 7 patients in one AP (0.8 %) and none in both. Presence of TSM was significantly associated with age (p = 0.002) and liver disease (p = 0.033) in univariate but not in multivariate analysis (p > 0.05). No association was found between acquisition parameters and TSM occurrence. Limited or severely limited HBP contrast uptake was observed in 87 patients (10.2 %), and TSM was never associated with severely limited HBP contrast uptake. CONCLUSION/CONCLUSIONS:TSM was present in approximately 12 % of gadoxetate disodium MRIs, rarely on both APs (2.3 %), and was poorly predicted. TSM was never associated with severely limited HBP contrast uptake.

Purpose/UNASSIGNED:To use convolutional neural networks (CNNs) for fully automated MRI segmentation of the glenohumeral joint and evaluate the accuracy of three-dimensional (3D) MRI models created with this method. Materials and Methods/UNASSIGNED:Shoulder MR images of 100 patients (average age, 44 years; range, 14-80 years; 60 men) were retrospectively collected from September 2013 to August 2018. CNNs were used to develop a fully automated segmentation model for proton density-weighted images. Shoulder MR images from an additional 50 patients (mean age, 33 years; range, 16-65 years; 35 men) were retrospectively collected from May 2014 to April 2019 to create 3D MRI glenohumeral models by transfer learning using Dixon-based sequences. Two musculoskeletal radiologists performed measurements on fully and semiautomated segmented 3D MRI models to assess glenohumeral anatomy, glenoid bone loss (GBL), and their impact on treatment selection. Performance of the CNNs was evaluated using Dice similarity coefficient (DSC), sensitivity, precision, and surface-based distance measurements. Measurements were compared using matched-pairs Wilcoxon signed rank test. Results/UNASSIGNED:value range, .097-.99). Conclusion/UNASSIGNED:© RSNA, 2020.

Background: Anatomical structure affects function. The morphology of articulations dictates the way forces will travel through the joint. A better understanding of the structure and function of the wrist will enhance our ability to diagnose and treat wrist conditions. Two wrist types have been described based on the morphology of the midcarpal joint. Biomechanically it is important to see if these 2-dimensional (2D) observations reflect articular contact areas. Our purpose was to assess the correlation between measurements performed on wrist radiographs (2D) to measurements performed on 3-dimensional (3D) computed tomography (CT). Methods: Retrospective review of a database of normal wrist radiographs and corresponding normal CT scans. Only imaging pairs with normal carpal alignment and technically optimal imaging were included. Evaluations included lunate, capitate and wrist type, capitate circumference, percent capitate circumference and volume that articulates with the lunate, scapholunate ligament, scaphoid, hamate, trapezoid, base of the index and middle and ring metacarpal bones. Results: Midcarpal joint radiographic measurements were positively correlated with measurements on CT scans. Correlations were 0.51 for capitate type and 0.71 for lunate type with both p < 0.001. Percent contact of the lunate with the hamate: r was 0.74 p < 0.001. Using logistic regression analysis, percent lunate-hamate contact on CT was a significant predictor of radiographic lunate type 2 p < 0.001. Percent contact area between lunate and hamate > 7.8% on CT scan achieved a sensitivity of 100% and specificity 79.4% for a type 2 lunate. Conclusions: 1) Good correlations found between CT and plain radiographs in lunate type, capitate type, and midcarpal joint contact support the use of plain radiographs to describe contact between the carpal bones in the clinical setting. 2) The retrospective nature of this study limited the technical quality of the measurements. Volumetric analysis may aid in a more exact evaluation of surface contact area.

PURPOSE/OBJECTIVE:To evaluate the correlation between liver stiffness as measured on MR elastography and T1 and T2 relaxation times from T1 and T2 mapping with clinical parameters of liver disease, including the MELD score, MELD-Na and ALBI grade, and endoscopically visible esophageal varices. MATERIALS AND METHODS/METHODS:223 patients with known or suspected liver disease underwent MRI of the liver with T1 mapping (Look-Locker sequence) and 2D SE-EPI MR elastography (MRE) sequences. 139 of these patients also underwent T2 mapping with radial T2 FS sequence. Two readers measured liver stiffness, T1 relaxation times and T2 relaxation times, and assessed qualitative features such as presence or absence of cirrhosis, ascites, spleen length, and varices on conventional MRI images. A third reader collected the clinical data (MELD score, MELD-Na Score, ALBI grade, and results of endoscopy in 78 patients). RESULTS:Significant moderate correlation was found between MELD score and all three imaging techniques for both readers (MRE, r = 0.35 and 0.28; T1 relaxometry, r = 0.30 and 0.29; T2 relaxometry, r = 0.45, and 0.37 for reader 1 and reader 2 respectively). Correlation with MELD-Na score was even higher (MRE, r = 0.49 and 0.40; T1, r = 0.45 and 0.41; T2, r = 0.47 and 0.35 for reader 1 and reader 2 respectively). Correlations between MRE and ALBI grade was significant and moderate for both readers: r = 0.39 and 0.37, higher than T1 relaxometry (r = 0.22 and 0.20) and T2 relaxometry (r = 0.17, and r = 0.24). Significant moderate correlations were found for both readers between MRE and the presence of varices on endoscopy (r = 0.28 and 0.30). MRE and T1 relaxometry were significant predictors of varices at endoscopy for both readers (MRE AUC 0.923 and 0.873; T1 relaxometry AUC = 0.711 and 0.675 for reader 1 and reader 2 respectively). Cirrhotic morphology (AUC = 0.654), spleen length (AUC = 0.610) and presence of varices in the upper abdomen on MRI (AUC of 0.693 and 0.595) were all significant predictors of endoscopic varices. Multivariable logistic regression model identified that spleen length and liver MRE were significant independent predictors of endoscopic varices for both readers. CONCLUSION/CONCLUSIONS:MR elastography, T1 and T2 relaxometry demonstrated moderate positive correlation with the MELD score and MELD-Na Score. Correlation between MRE and ALBI grade was superior to T1 and T2 relaxometry methods. MRE performed better than T1 and T2 relaxometry to predict the presence of varices at endoscopy. On multivariate analyses, spleen length and MRE were the only two significant independent predictors of endoscopic varices.

Purpose/UNASSIGNED:To evaluate pulmonary embolism (PE) prevalence at CT pulmonary angiography in patients testing positive for coronavirus disease 2019 (COVID-19) and factors associated with PE severity. Materials and Methods/UNASSIGNED:value < .05 was considered significant. Results/UNASSIGNED:< .001). One additional patient with negative results at CT pulmonary angiography had deep venous thrombosis, thus resulting in 38.7% with PE or deep venous thrombosis, despite 40% receiving prophylactic anticoagulation. Other factors did not demonstrate significant PE association. Conclusion/UNASSIGNED:© RSNA, 2020.