Faculty Bibliography

Purpose or Case Report: To evaluate the reliability of the UTD classification system Table A. Cross-tabulation of results summarizing inter-reader agreement. There are three distinct reader pairs: score 1 is the score from the arbitrarily designated first reader in each pair and score 2 is from the remaining reader in each pair. Numbers in red denote instances of disagreement. Methods &Materials: This IRB approved, retrospective study included 129 renal ultrasound examinations performed from May 2010 - May 2015 in patients less than 6 months of age for the clinical indication of prenatal hydronephrosis identified by key word search in PACS. Three pediatric radiologists independently reviewed each study for the following: anterior posterior renal pelvic diameter (APRPD), central calyceal dilation (CCD), peripheral calyceal dilation (PPD), renal parenchymal appearance (PA), renal parenchymal thickness (PT), ureteral abnormality, and bladder abnormality. Readers assigned each study a UTD category (normal, UTD P1, UTD P2, UTD P3). Inter-rater percent agreement for individual criteria and overall UTD categorization was assessed. Results: There was overall good inter-reader agreement in assessment of individual criteria (APRPKD, PA, PT, ureter, and bladder) ranging from 85.3 to 96.1% for 3 reader pairs. Inter-reader agreement for CCD and PCD was slightly lower, ranging from 69.0 to 97.7%. Inter-reader agreement for overall risk assesment ranged from 50.4 to 67.4%. Agreement across 3 readers was 48.8% for CCD, 64.3% for PCD, and 37.2% for overall risk stratification. Conclusions: The new UTD classification system is intended to guide clinical management of postnatal urinary tract dilation. For it to be widely accepted and useful, users need to apply it with precision and accuracy. Poor agreement for categorization of risk assessment among our experienced readers suggests that further clarification of the system or training for users is necessary for its optimal use in clinical practice. (Table presented)

Quantitative standardized uptake values (SUVs) from fluorine-18 (18F) fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) are commonly used to evaluate the extent of disease and response to treatment in breast cancer patients. Recently, PET/magnetic resonance imaging (MRI) has been shown to qualitatively detect metastases from various primary cancers with similar sensitivity to PET/CT. However, quantitative validation of PET/MRI requires assessing the reliability of SUVs from MR attenuation correction (MRAC) relative to CT attenuation correction (CTAC). The purpose of this retrospective study was to assess the utility of PET/MRI-derived SUVs in breast cancer patients by testing the hypothesis that SUVs derived from MRAC correlate well with those from CTAC. Between August 2012 and May 2013, 35 breast cancer patients (age 37-78 years, 1 man) underwent clinical 18F-FDG PET/CT followed by PET/MRI. One hundred seventy metastases were seen in 21 of 35 patients; metastases to bone in 16 patients, to liver in seven patients, and to nonaxillary lymph nodes in eight patients were sufficient for statistical analysis on an organ-specific per patient basis. SUVs in the most FDG-avid metastasis per organ per patient from PET/CT and PET/MRI were measured and compared using Pearson's correlations. Correlations between CTAC- and MRAC-derived SUVmax and SUVmean in 31 metastases to bone, liver, and nonaxillary lymph nodes were strong overall (rho = 0.80, 0.81). SUVmax and SUVmean correlations were also strong on an organ-specific basis in 16 bone metastases (rho = 0.76, 0.74), seven liver metastases (rho = 0.85, 0.83), and eight nonaxillary lymph node metastases (rho = 0.95, 0.91). These strong organ-specific correlations between SUVs from PET/CT and PET/MRI in breast cancer metastases support the use of SUVs from PET/MRI for quantitation of 18F-FDG activity.

BACKGROUND & AIMS: Establishing accurate non-invasive methods of liver fibrosis quantification remains a major unmet need. Here, we assessed the diagnostic value of a multiparametric magnetic resonance imaging (MRI) protocol including diffusion-weighted imaging (DWI), dynamic contrast-enhanced (DCE)-MRI and magnetic resonance elastography (MRE) in comparison with transient elastography (TE) and blood tests [including ELF (Enhanced Liver Fibrosis) and APRI] for liver fibrosis detection. METHODS: n this single center cross-sectional study, we prospectively enrolled 60 subjects with liver disease who underwent multiparametric MRI (DWI, DCE-MRI and MRE), TE and blood tests. Correlation was assessed between non-invasive modalities and histopathologic findings including stage, grade, and collagen content, while accounting for covariates such as age, sex, BMI, HCV status and MRI-derived fat and iron content. ROC curve analysis evaluated the performance of each technique for detection of moderate-to-advanced liver fibrosis (F2-F4) and advanced fibrosis (F3-F4). RESULTS: MRE provided the strongest correlation with fibrosis stage (r=0.66, p <0.001), inflammation grade (r=0.52, p <0.001) and collagen content (r=0.53, p=0.036). For detection of moderate-to-advanced fibrosis (F2-F4), AUCs were 0.78, 0.82, 0.72, 0.79, 0.71 for MRE, TE, DCE-MRI, DWI, APRI, respectively. For detection of advanced fibrosis (F3-F4), AUCs were 0.94, 0.77, 0.79, 0.79, 0.70, respectively CONCLUSIONS: MRE provides the highest correlation with histopathologic markers and yields high diagnostic performance for detection of advanced liver fibrosis and cirrhosis, compared to DWI, DCE-MRI, TE and serum markers

PURPOSE: To assess interplatform reproducibility of liver stiffness (LS) and spleen stiffness (SS) measured with magnetic resonance elastography (MRE) based on a 2D gradient echo (GRE) sequence. MATERIALS AND METHODS: This prospective Health Insurance Portability and Accountability Act (HIPAA)-compliant and Institutional Review Board (IRB)-approved study involved 12 subjects (five healthy volunteers and seven patients with liver disease). A multislice 2D-GRE-based MRE sequence was performed using two systems from different vendors (3.0T GE and 1.5T Siemens) on the same day. Two independent observers measured LS and SS on confidence maps. Bland-Altman analysis (with coefficient of reproducibility, CR), coefficient of variability (CV), and intraclass correlation (ICC) were used to analyze interplatform, intra- and interobserver variability. Human data were validated using a gelatin-based phantom. RESULTS: There was excellent reproducibility of phantom stiffness measurement (CV 4.4%). Mean LS values were 3.44-3.48 kPa and 3.62-3.63 kPa, and mean SS values were 7.54-7.91 kPa and 8.40-8.85 kPa at 3.0T and 1.5T for observers 1 and 2, respectively. The mean CVs between platforms were 9.2%-11.5% and 13.1%-14.4% for LS and SS, respectively, for observers 1 and 2. There was excellent interplatform reproducibility (ICC >0.88 and CR <36.2%) for both LS and SS, and excellent intra- and interobserver reproducibility (intraobserver: ICC >0.99, CV <2.1%, CR <6.6%; interobserver: ICC >0.97, CV and CR <16%). CONCLUSION: This study demonstrates that 2D-GRE MRE provides platform- and observer-independent LS and SS measurements. J. Magn. Reson. Imaging 2015.

Objectives PET/MR may be used in the evaluation of cognitively impaired patients. There are known quantitative differences between PET images obtained on PET/MR scanners when reconstructed with Dixon-MR, CT-based or atlas-based attenuation correction (AC) maps. This study seeks to assess the impact, if any, of these three-different AC methods on the blinded visual interpretation of regional hypometabolism in patients with cognitive impairment. Methods Forty-five minutes following injection of 10 mCi of FDG, 15 patients with cognitive impairment underwent brain PET/CT. PET/MR scanning with a 10 minute PET acquisition and Dixon MR imaging was subsequently performed on a Siemens Biograph mMR scanner under an IRB-approved protocol, at approximately two hours post-injection. A manufacturer-provided non-product offline reconstruction tool was used to reconstruct PET data obtained from PET/MR with AC based on the patient's own CT images, a Dixon-MR derived AC map and an atlas-based AC map that combined Dixon-MR with a segmentation of bony skull structures. Two nuclear medicine physicians blindly scored brain regions (frontal, temporal, parietal, occipital, precuneus) as normal versus hypometabolic using 2D and 3D images generated by MIM software. Abnormal regions were scored as mild, moderate, or severely hypometabolic (score of 0, 1, 2 or 3 respectively). The hypometabolism scores obtained using the different methods of AC were compared and reader agreement assessed. All statistical tests were conducted at the two-sided 5% significance level using SAS 9.3 (SAS Institute, Cary, NC). Results Regional hypometabolism versus normal metabolism was correctly classified (accuracy) for 150 regions in 15 patients by two readers on atlas- and Dixon-based AC map PET reconstructions (versus CT reference AC) for 94% (90 - 96% c.i.) and 93% (89 - 96% c.i.) of all regions. The averaged sensitivity/specificity for detection of any regional hypometabolism was 95%/94% and 90%/91% for atlas-based and Dixon-based AC maps, respectively, compared to the reference standard CT images. The mean absolute error of regional hypometabolism scores for atlas- and Dixon-based PET reconstructions (versus CT) was 0.25 +/- 0.44 and 0.21 +/- 0.42 . There were no statistically significant differences between the visual assessments. Intra-reader agreement for detection of regional hypometabolism was high, with similar outcome assessments when using atlas- and Dixon-corrected PET data in 93% and 93% of scored regions, respectively. The simple kappa coefficient to assess reader agreement in terms of hypometabolism versus normal regions was 0.82 for atlas- and 0.84 for Dixon-based AC. The weighted kappa coefficient to assess reader agreement in terms of the hypometabolism score was 0.75 for atlas- and 0.77 for Dixon-AC. Conclusions Despite the more accurate FDG SUV quantification with CT-based and atlas-based attenuation correction in brain PET/MR compared to Dixon AC, there were no measureable differences between the three AC methods with respect to visual identification of regional hypometabolism in the evaluation of cognitively impaired patients

RATIONALE AND OBJECTIVES: This study aimed to assess the most common publication types in radiology journals, as well as temporal trends and association with citation frequency. MATERIALS AND METHODS: PubMed was searched to extract all published articles having the following "Publication Type" indices: "validation studies," "meta-analysis," "clinical trial," "comparative study," "evaluation study," "guideline," "multicenter study," "randomized study," "review," "editorial," "case report," and "technical report." The percentage of articles within each category published within clinical radiology journals was computed. Normalized percentages for each category were also computed on an annual basis. Citation counts within a 2-year window following publication were obtained using Web of Science. Overall trends were assessed. RESULTS: Publication types with the highest fraction in radiology journals were technical reports, evaluation studies, and case reports (4.8% to 5.8%). Publication types with the lowest fraction in radiology journals were randomized trials, multicenter studies, and meta-analyses (0.8% to 1.5%). Case reports showed a significant decrease since 1999, with accelerating decline since 2007 (P = 0.002). Publication types with highest citation counts were meta-analyses, guidelines, and multicenter studies (8.1 +/- 10.7 to 12.9 +/- 5.1). Publication types with lowest citation counts were case reports, editorials, and technical reports (1.4 +/- 2.4 to 2.9 +/- 4.3). The representation in radiology journals and citation frequency of the publication types showed weak inverse correlation (r = -0.372). CONCLUSIONS: Radiology journals have historically had relatively greater representation of less frequently cited publication types. Various strategies, including methodological training, multidisciplinary collaboration, national support networks, as well as encouragement of higher level of evidence by funding agencies and radiology journals themselves, are warranted to improve the impact of radiological research.

PURPOSE: To evaluate the length of capsular contact of dominant lesions on multiparametric prostate magnetic resonance imaging (MRI) for predicting extraprostatic extension (EPE) and to determine a threshold value to apply in clinical practice. MATERIALS AND METHODS: Ninety patients undergoing 3T prostate MRI before prostatectomy were included. Two independent readers (R1, R2) recorded for each lobe the presence or absence of capsular irregularity on T2 -weighted imaging (T2 WI) and of overt measurable EPE. Readers also recorded the length of capsular contact of each lobe's dominant lesion for T2 WI and the apparent diffusion coefficient (ADC) map. Based on prostatectomy specimens, EPE was recorded for each lobe and classified as focal (single focus