Faculty Bibliography

Fluorodeoxyglucose (FDG) positron emission tomography-magnetic resonance (PET/MR) is useful for the evaluation of cognitively-impaired patients. This study aims to assess two different attenuation correction (AC) methods (Dixon-MR and atlas-based) versus index-standard computed tomography (CT) AC for the visual interpretation of regional hypometabolism in patients with cognitive impairment. Two board-certified nuclear medicine physicians blindly scored brain region FDG hypometabolism as normal versus hypometabolic using two-dimensional (2D) and 3D FDG PET/MR images generated by MIM software. Regions were quantitatively assessed as normal versus mildly, moderately, or severely hypometabolic. Hypometabolism scores obtained using the different methods of AC were compared, and interreader, as well as intra-reader agreement, was assessed. Regional hypometabolism versus normal metabolism was correctly classified in 16 patients on atlas-based and Dixon-based AC map PET reconstructions (vs. CT reference AC) for 94% (90%-96% confidence interval [CI]) and 93% (89%-96% CI) of scored regions, respectively. The averaged sensitivity/specificity for detection of any regional hypometabolism was 95%/94% (P = 0.669) and 90%/91% (P = 0.937) for atlas-based and Dixon-based AC maps. Interreader agreement for detection of regional hypometabolism was high, with similar outcome assessments when using atlas- and Dixon-corrected PET data in 93% (Κ =0.82) and 93% (Κ =0.84) of regions, respectively. Intrareader agreement for detection of regional hypometabolism was high, with concordant outcome assessments when using atlas- and Dixon-corrected data in 93%/92% (Κ =0.79) and 92/93% (Κ =0.78). Despite the quantitative advantages of atlas-based AC in brain PET/MR, routine clinical Dixon AC yields comparable visual ratings of regional hypometabolism in the evaluation of cognitively impaired patients undergoing brain PET/MR and is similar in performance to CT-based AC. Therefore, Dixon AC is acceptable for the routine clinical evaluation of dementia syndromes.

BACKGROUND: Multiparametric magnetic resonance imaging (mpMRI) combining different techniques such as MR elastography (MRE) has emerged as a noninvasive approach to diagnose and stage liver fibrosis with high accuracy allowing for anatomical and functional information. PURPOSE: To assess the diagnostic performance of mpMRI including qualitative and quantitative assessment of MRE, liver surface nodularity (LSN) measurement, hepatic enhancement ratios postgadoxetic acid, and serum markers (APRI, FIB-4) for the detection of liver fibrosis. STUDY TYPE: IRB-approved retrospective. SUBJECTS: Eighty-three adult patients. FIELD STRENGTH/SEQUENCE: 1.5T and 3.0T MR systems. MRE and T1 -weighted postgadoxetic acid sequences. ASSESSMENT: Two independent observers analyzed qualitative color-coded MRE maps on a scale of 0-3. Regions of interest were drawn to measure liver stiffness on MRE stiffness maps and on pre- and postcontrast T1 -weighted images to measure hepatic enhancement ratios. Software was used to generate LSN measurements. Histopathology was used as the reference standard for diagnosis of liver fibrosis in all patients. STATISTICAL TESTS: A multivariable logistic analysis was performed to identify independent predictors of liver fibrosis. Receiver operating characteristic (ROC) analysis evaluated the performance of each imaging technique for detection of fibrosis, in comparison with serum markers. RESULTS: Liver stiffness measured with MRE provided the strongest correlation with histopathologic fibrosis stage (r = 0.74, P < 0.001), and the highest diagnostic performance for detection of stages F2-F4, F3-F4, and F4 (areas under the curve [AUCs] of 0.87, 0.91, and 0.89, respectively, P < 0.001) compared to other methods. Qualitative assessment of MRE maps showed fair to good accuracy for detection of fibrosis (AUC range 0.76-0.84). Multivariable logistic analysis identified liver stiffness and FIB-4 as independent predictors of fibrosis with AUCs of 0.90 (F2-F4), 0.93 (F3-F4) and 0.92 (F4) when combined. DATA CONCLUSION: Liver stiffness measured with MRE showed the best performance for detection of liver fibrosis compared to LSN and gadoxetic acid uptake, with slight improvement when combined with FIB-4. LEVEL OF EVIDENCE: 3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2017.

PURPOSE: To capture shifts in breast imaging through 21years of scientific meeting abstracts. MATERIALS AND METHODS: RSNA meeting programs (1995-2015) were searched to identify breast imaging scientific oral abstracts. Abstract year, author gender and degree, country, state, study design, modality, topic, funding and disclosures were recorded. Spearman correlation was performed. RESULTS: There was an increase in %women first authors (rs=0.81, p<0.001), in %international abstracts (rs=-0.64, p=0.0002) and in industry funding (rs=0.766, p<0.001). CONCLUSION: %Women first author presenters and %international presence and %industry support increased over time. These areas of flux may be useful for continued tracking.

OBJECTIVE:To correlate qualitative and quantitative diffusion weighted imaging (DWI) characteristics of intrahepatic cholangiocarcinoma (ICC) with histopathologic tumour grade and fibrosis content. METHODS:Fifty-one patients (21M/30F; mean age 61y) with ICC and MRI including DWI were included in this IRB-approved multicentre retrospective study. Qualitative tumour features were assessed. Tumour apparent diffusion coefficient (ADC) mean, minimum, and normalized (nADCliver) values were computed. Tumour grade [well(G1), moderately(G2), or poorly differentiated(G3)] and tumour fibrosis content [minimal(1), moderate(2), or abundant(3)] were categorized pathologically. Imaging findings and ADC values were compared with pathologic measures. Utility of ADC values for predicting tumour grade was assessed using ROC analysis. RESULTS:51 ICCs (mean size 6.5±1.1 cm) were assessed. 33/51(64%) of ICCs demonstrated diffuse hyperintensity and 15/51(29%) demonstrated target appearance on DWI. Infiltrative morphology (p=0.02) and tumour size (p=0.04) were associated with G3. ADCmean and nADCmean of G3 (1.32±0.47x10-3 mm2/sec and 0.97±0.95) were lower than G1+G2 (1.57±0.39x10-3 mm2/sec and 1.24±0.49; p=0.03 and p=0.04). ADCmean and nADCmean were inversely correlated with tumour grade (p<0.025). No correlation was found between ADC and tumour fibrosis content. AUROC, sensitivity and specificity of nADCmean for G3 versus G1+G2 were 0.71, 89.5% and 55.5%. CONCLUSION/CONCLUSIONS:ADC quantification has reasonable accuracy for predicting ICC grade. KEY POINTS/CONCLUSIONS:• ADC quantification was useful for predicting ICC tumour grade. • Infiltrative tumour morphology and size were associated with poorly differentiated ICCs. • ADC values depended more on ICC tumour grade than fibrosis content. • Ability to predict ICC tumour grade non-invasively could impact patient management.

Purpose To assess adherence with annual or biennial screening mammography after a diagnosis of high-risk lesion(s) at stereotactic biopsy with or without surgical excision and to identify clinical factors that may affect screening adherence after a high-risk diagnosis. Materials and Methods This institutional review board-approved HIPAA-compliant retrospective study included 208 patients who underwent stereotactic biopsy between January 2012 and December 2014 that revealed a high-risk lesion. Whether the patient underwent surgical excision and/or follow-up mammography was documented. Adherence of these women to a protocol of subsequent mammography within 1 year (9-18 months) or within 2 years (9-30 months) was compared with that of 45 508 women with normal screening mammograms who were imaged during the same time period at the same institution. Possible factors relevant to postdiagnosis management and screening adherence were assessed. Consultation with a breast surgeon was identified by reviewing clinical notes. Uptake of pharmacologic chemoprevention following diagnosis (patient decision to take chemopreventive medications) was assessed. The Fisher exact test was used to compare annual or biennial screening adherence rates. Binary logistic regression was used to identify factors predictive of whether women returned for screening within selected time frames. Results In total, 913 (1.3%) of 67 874 women were given a recommendation to undergo stereotactic biopsy, resulting in diagnosis of 208 (22.8%) of 913 high-risk lesions. Excluding those with a prior personal history of breast cancer or upgrade to cancer at surgery, 124 (66.7%) of 186 women underwent surgery and 62 (33.3%) did not. Overall post-high-risk diagnosis adherence to annual or biennial mammography was similar to that in control subjects (annual, 56.4% vs 50.8%, P = .160; biennial, 62.0% vs 60.1%, P = .630). Adherence was significantly better in the surgical group than in the nonsurgical group for annual mammography (70.0% vs 32.0%; odds ratio [OR] = 5.0; 95% confidence interval [CI]: 2.4, 10.1; P < .001) and for biennial mammography (74.3% vs 40.0%; OR = 4.3; 95% CI: 2.1, 8.8; P < .001). Among the patients in the nonsurgical group, those adherent to annual or biennial mammography were significantly more likely to have seen a breast surgeon than the nonadherent women (annual, 77.3% vs 35.7%, P = .005; biennial, 67.9% vs 36.4%, P = .045). All patients receiving chemopreventive agents underwent a surgical consultation (100%; n = 21). Conclusion Although diagnosis of a high-risk lesion at stereotactic breast biopsy did not compromise overall adherence to subsequent mammographic screening, patients without surgical excision, particularly those who did not undergo a surgical consultation, had significantly lower imaging adherence and chemoprevention uptake as compared with their counterparts who underwent surgery, suggesting that specialist care may be important in optimizing management. © RSNA, 2018.

We seek to elucidate the underlying pathophysiology of injury sustained after mild traumatic brain injury (MTBI) using multi-shell diffusion MRI, deriving compartment-specific WM tract integrity (WMTI) metrics. WMTI allows a more biophysical interpretation of WM changes by describing microstructural characteristics in both intra- and extra-axonal environments. Thirty-two patients with MTBI within 30 days of injury and twenty-one age- and sex-matched controls were imaged on a 3T MR scanner. Multi-shell diffusion acquisition was performed with 5 b-values (250 - 2500 s/mm²) along 6 - 60 diffusion encoding directions. Tract-based spatial statistics (TBSS) was used with family-wise error (FWE) correction for multiple comparisons. TBSS results demonstrate focally lower intra-axonal diffusivity (D_axon) in MTBI patients in the splenium of the corpus callosum (sCC) (p < 0.05, FWE-corrected). The Area Under the Curve (AUC)-value for was 0.76 with low sensitivity of 46.9%, but 100% specificity. These results indicate that D_axon may be a useful imaging biomarker highly specific for MTBI-related WM injury. The observed decrease in D_axon suggests restriction of the diffusion along the axons occurring shortly after injury.

RATIONALE: Recent evidence suggests that Obstructive Sleep Apnea (OSA) may be a risk factor for developing Mild Cognitive Impairment and Alzheimer's disease. However, how sleep apnea affects longitudinal risk for Alzheimer's disease is less well understood. OBJECTIVE: To test the hypothesis that there is an association between severity of OSA and longitudinal increase in amyloid burden in cognitively normal elderly. METHODS: Data was derived from a 2-year prospective longitudinal study that sampled community-dwelling healthy cognitively normal elderly. Subjects were healthy volunteers between the ages of 55 to 90, were non-depressed and had a consensus clinical diagnosis of cognitively normal. CSF Amyloid beta was measured using ELISA. Subjects received Pittsburgh compound B Positron Emission Tomography scans following standardized procedures. Monitoring of OSA was completed using a home sleep recording device. MEASUREMENTS AND MAIN RESULTS: We found that severity of OSA indices (lnAHIall [F1,88=4.26, p<.05] and lnAHI4% [F1,87=4.36, p<.05]) were associated with annual rate of change of CSF Abeta42 using linear regression after adjusting for age, sex, BMI and ApoE4 status. LnAHIall and lnAHI4 were not associated with increases in ADPiB-mask most likely due to the small sample size although there was a trend for lnAHIall (F1,28=2.96, p=.09 and F1,28=2.32, n.s. respectively). CONCLUSION: In a sample of cognitively normal elderly, OSA was associated with markers of increased amyloid burden over the 2 year follow-up. Sleep fragmentation and/or intermittent hypoxia from OSA are likely candidate mechanisms. If confirmed, clinical interventions for OSA may be useful in preventing amyloid build-up in cognitively normal elderly.

PURPOSE/OBJECTIVE:To evaluate whether false-positive stereotactic vacuum-assisted breast biopsy (SVAB) affects subsequent mammographic screening adherence. MATERIALS AND METHODS/METHODS:tests. RESULTS:There were 913 SVABs performed in 2012 to 2014 for imaging detected lesions; of these, malignant or high-risk lesions or biopsies resulting in a recommendation of surgical excision were excluded, leaving 395 SVABs yielding benign pathology in 395 women. Findings were matched with a control population consisting of 45,126 women who had a BI-RADS 1 or 2 screening mammogram and did not undergo breast biopsy. In all, 191 of 395 (48.4%) women with a biopsy with benign results and 22,668 of 45,126 (50.2%) women without biopsy returned for annual follow-up >9 months and ≤18 months after the index examination (P = .479). In addition, 57 of 395 (14.4%) women with a biopsy with benign results and 3,336 of 45,126 (7.4%) women without biopsy returned for annual follow-up >18 months after the index examination (P < .001). Older women, women with personal history of breast cancer, and women with postbiopsy complication after benign SVAB were more likely to return for screening (P = .026, P = .028, and P = .026, respectively). CONCLUSION/CONCLUSIONS:The findings in our study suggest that SVABs with benign results do not negatively impact screening mammography adherence. The previously described "harms" of false-positive mammography and biopsy may be exaggerated.