Faculty Bibliography

To compare utilization of CT pulmonary angiogram (CTA) for diagnosis of pulmonary embolism (PE) in an emergency department (ED) with unstructured CT ordering to published rates of CT positivity in other EDs including those employing decision support and to identify pathways for improved utilization via collaboration with our pathology and ED colleagues. Two hundred seventeen patients over a 2.5-month time period who received a CTA for PE were reviewed with exclusion of pediatric patients and all sub-optimal, non-diagnostic, or equivocal scans; 21 were excluded leaving a sample of 196 patients. The rate of PE diagnosis and association of PE positivity with selected factors (D-dimer testing) was assessed. The percentage of cases positive for PE was 10.7 % (21/196) which is similar to the frequently published rate of 10 % in other emergency departments including settings that have studied the use of decision support. D-dimer testing was performed in 40.3 % of cases. In 29.6 % (58/196) of subjects, D-dimer was positive, 10.7 % (21/196) was negative, and 59.7 % (117/196) was not assessed. Prevalence of PE among D-dimer negative (0 %, 0/21) was lower versus positive D-dimer (12.1 %, 7/58) and unknown D-dimer patients (12.0 %, 14/117). D-dimer had 100 % (21/21) negative predictive value for the diagnosis of PE. While this suggests that D-dimer is useful to rule-out PE, due to the small number of patients with PE, the 95 % confidence intervals are wide and the post-test likelihood of PE could be as high as 14 %. The rate of CT positivity for PE in an ED with unstructured CT ordering is similar to that in other published series including as series in which decision support was used. While D-dimer had high negative predictive value, large studies are needed to confirm this high sensitivity and potentially increase its use in ruling out PE without CT and to reduce CT ordering particularly in patients with sufficiently low clinical pre-test probability of PE.

OBJECTIVE: To compare performance of single-injection blood pool agent (gadofosveset trisodium, BPA) against dual-injection extracellular contrast (gadopentetate dimeglumine, ECA) for MRA/MRV in assessment of suspected vascular TOS. MATERIALS AND METHODS: Thirty-one patients referred for vascular TOS evaluation were assessed with BPA (n=18) or ECA (n=13) MRA/MRV in arm abduction and adduction. Images were retrospectively assessed for: image quality (1=non-diagnostic, 5=excellent), vessel contrast (1=same signal as muscle, 4=much brighter than muscle) and vascular pathology by two independent readers, with a separate experienced reader providing reference assessment of vascular pathology. RESULTS: Median image quality was diagnostic or better (score >/=3) for ECA and BPA at all time points, with BPA image quality superior at abduction late (BPA 4.5, ECA 4, p=0.042) and ECA image quality superior at adduction-early (BPA 4.5; ECA 4.0, p=0.018). High qualitative vessel contrast (mean score >/=3) was observed at all time points with both BPA and ECA, with superior BPA vessel contrast at abduction-late (BPA 3.97+/-0.12; ECA 3.73+/-0.26, p=0.007) and ECA at adduction-early (BPA 3.42+/-0.52; ECA 3.96+/-0.14, p<0.001). Readers readily identified arterial and venous pathology with BPA, similar to ECA examinations. CONCLUSION: Single-injection BPA MRA/MRV for TOS evaluation demonstrated diagnostic image quality and high vessel contrast, similar to dual-injection ECA imaging, enabling identification of fixed and functional arterial and venous pathology.

Purpose: To review radiation dose exposure for patients undergoing IVC filter placement in order to infer quantitative guidelines for expected doses. To identify strategies for targeted dose reduction. Materials and Methods: Records of 230 consecutive cases of IVC filter placement in Interventional Radiology at a single university hospital between 1/4/12 and 6/7/13 were reviewed. Patients under age 18 and patients with variant anatomy (e.g. duplicated IVC) or caval thrombosis were excluded. Radiation dose (mGy) was recorded from the fluoroscopic detector system; access site and patient information were noted. Subset analyses were performed, including analysis before and after exclusion of outliers (more than two SD from the mean) and before and after exclusion of cases without contrast (no DSA). Patients were stratified by access site, BMI, age, and gender; correlation with dose was analyzed using Spearman rank correlation and Mann-Whitney tests. Four access site categories were used: Right internal jugular (RIJ), left internal jugular (LIJ), right common femoral (RCF), and Other. Results: Mean radiation dose in all subjects was 67.55 mGy, and after outliers and non-contrast cases were excluded, 51.35 mGy.Radiation dose was highest in cases when IVC filters were placed via the RIJ compared with LIJ, RCF, and other access sites. Radiation dose was significantly lower in cases with filters placed via RCF than in those with filters placed via RIJ (p=0.018). Conclusion: Analysis of radiation dose in a standardized procedure-IVC filter placement-provides valuable information on expected dose range and potential dose reduction strategies. Access via RIJ (vs. RCF) resulted in significantly higher dose, raising the question: should a standard access site for IVC filter placement be considered? Additionally, this model will be implemented to identify dose reduction strategies for other standard interventional procedures. (Table Presented)

OBJECTIVE. The purpose of this review is to illustrate various applications of gadofosveset trisodium in evaluating abdominal and peripheral vascular disease. The basic properties, technical considerations, and clinical and potential future applications of gadofosveset are described. CONCLUSION. Gadofosveset trisodium facilitates comprehensive high-resolution arterial and venous MR angiography. Because of its prolonged intravascular residence time, gadofosveset trisodium is particularly useful for evaluating venous, dynamic, and functional vascular disease with a single low-dose contrast injection.

Purpose:To evaluate diagnostic performance of three nonenhanced methods: variable-refocusing-flip angle (FA) fast spin-echo (SE)-based magnetic resonance (MR) angiography (variable FA MR) and constant-refocusing-FA fast SE-based MR angiography (constant-FA MR) and flow-sensitive dephasing (FSD)-prepared steady-state free precession MR angiography (FSD MR) for calf arteries, with dual-injection three-station contrast material-enhanced MR angiography (gadolinium-enhanced MR) as reference.Materials and Methods:This prospective study was institutional review board approved and HIPAA compliant, with informed consent. Twenty-one patients (13 men, eight women; mean age, 62.6 years) underwent calf-station variable-FA MR, constant-FA MR, and FSD MR at 1.5 T, with gadolinium-enhanced MR as reference. Image quality and stenosis severity were assessed in 13 segments per leg by two radiologists blinded to clinical data. Combined constant-FA MR and FSD MR reading was also performed. Methods were compared (logistic regression for correlated data) for diagnostic accuracy.Results:Of 546 arterial segments, 148 (27.1%) had a hemodynamically significant (>/= 50%) stenosis. Image quality was satisfactory for all nonenhanced MR sequences. FSD MR was significantly superior to both other sequences (P < .0001), with 5-cm smaller field of view; 9.6% variable-FA MR, 9.6% constant-FA MR, and 0% FSD MR segmental evaluations had nondiagnostic image quality scores, mainly from high diastolic flow (variable-FA MR) and motion artifact (constant-FA MR). Stenosis sensitivity and specificity were highest for FSD MR (80.3% and 81.7%, respectively), compared with those for constant-FA MR (72.3%, P = .086; and 81.8%, P = .96) and variable-FA MR (75.9%, P = .54; and 75.6%, P = .22). Combined constant-FA MR and FSD MR had superior sensitivity (81.8%) and specificity (88.3%) compared with constant-FA MR (P = .0076), variable-FA MR (P = .0044), and FSD MR (P = .0013). All sequences had an excellent negative predictive value (NPV): 93.2%, constant-FA MR; 94.7%, variable-FA MR; 91.7%, FSD MR; and 92.9%, combined constant-FA MR and FSD MR.Conclusion:At 1.5 T, all evaluated nonenhanced MR angiographic methods demonstrated satisfactory image quality and excellent NPV for hemodynamically significant stenosis.(c) RSNA, 2013Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12120859/-/DC1.

PURPOSE: The aim of this study was to evaluate all aspects of workflow in a large academic MRI department to determine whether process improvement (PI) efforts could improve key performance indicators (KPIs). METHODS: KPI metrics in the investigators' MR imaging department include daily inpatient backlogs, on-time performance for outpatient examinations, examination volumes, appointment backlogs for pediatric anesthesia cases, and scan duration relative to time allotted for an examination. Over a 3-week period in April 2011, key members of the MR imaging department (including technologists, nurses, schedulers, physicians, and administrators) tracked all aspects of patient flow through the department, from scheduling to examination interpretation. Data were analyzed by the group to determine where PI could improve KPIs. Changes to MRI workflow were subsequently implemented, and KPIs were compared before (January 1, 2011, to April 30, 2011) and after (August 1, 2011, to December 31, 2011) using Mann-Whitney and Fisher's exact tests. RESULTS: The data analysis done during this PI led to multiple changes in the daily workflow of the MR department. In addition, a new sense of teamwork and empowerment was established within the MR staff. All of the measured KPIs showed statistically significant changes after the reengineering project. CONCLUSIONS: Intradepartmental PI efforts can significantly affect KPI metrics within an MR imaging department, making the process more patient centered. In addition, the process allowed significant growth without the need for additional equipment or personnel.

OBJECTIVE: Total renal volume and changes in kidney volume are markers of disease progression in autosomal-dominant polycystic kidney disease (ADPKD) but are not used in clinical practice in part because of the complexity of manual measurements. This study aims to assess the intra- and interobserver reproducibility of a semiautomated renal volumetric algorithm using fluid-sensitive MRI pulse sequences. SUBJECTS AND METHODS: Renal volumes of 17 patients with ADPKD were segmented from high-resolution coronal HASTE and true fast imaging with steady-state precession (FISP) MR acquisitions. Measurements performed independently by four readers were repeated, typically after 7 days. Intraobserver agreement indexes were calculated for total kidney volume for each patient. Interobserver agreement indexes were obtained for the six paired combinations of readers as well as for two readers after rigorous formalized training. Pearson and concordance correlation coefficients, coefficients of variation (CVs), and 95% limits of agreement were determined. RESULTS: The HASTE and true FISP sequences performed similarly with a median intraobserver agreement of greater than 98.1% and a CV of less than 2.4% across all readers. The median interobserver agreement was greater than 95.2% and the CV was less than 7.1%, across all reader pairs. Reader training further lowered interobserver CV. The mean total kidney volume was 1420 mL (range, 331-3782 mL) for HASTE imaging and 1445 mL (range, 301-3714 mL) for true FISP imaging, with mean image processing times per patient of 43 and 28 minutes, respectively. CONCLUSION: This semiautomated MR volumetric algorithm provided excellent intraobserver and very good interobserver reproducibility using fluid-sensitive pulse sequences that emphasize cyst conspicuity.

Computed tomography (CT) is considered the imaging modality of choice in evaluation of renal lesions. The advantages of magnetic resonance imaging (MRI) compared to CT include superior soft tissue contrast, avoidance of ionizing radiation and iodinated contrast media, and the possibility of performing functional and advanced imaging techniques such as diffusion-weighted (DWI) and perfusion-weighted imaging (PWI). Although the traditional role of MRI in the evaluation of renal mass is primarily that of a problem-solving tool, DWI and PWI are expanding the role of MRI in management of renal cell cancers. DWI and PWI have shown considerable promise not only in renal lesion detection and characterization as benign or malignant, but also in assessment of renal cell cancer subtype and nuclear grade. Furthermore, these techniques have the potential to assist with tailoring patient- and disease-specific management by providing surgical planning in patients with localized renal cell cancer and assessing treatment response in patients with advanced renal cell cancer undergoing targeted chemotherapy

To determine the added value of reimaging the female pelvis with ultrasound (US) immediately following multidetector CT (MDCT) in the emergent setting. CT and US exams of 70 patients who underwent MDCT for evaluation of abdominal/pelvic pain followed by pelvic ultrasound within 48 h were retrospectively reviewed by three readers. Initially, only the CT images were reviewed followed by evaluation of CT images in conjunction with US images. Diagnostic confidence was recorded for each reading and an exact Wilcoxon signed rank test was performed to compare the two. Changes in diagnosis based on combined CT and US readings versus CT readings alone were identified. Confidence intervals (95%) were derived for the percentage of times US reimaging can be expected to lead to a change in diagnosis relative to the diagnosis based on CT interpretation alone. Ultrasound changed the diagnosis for the ovaries/adnexa 8.1% of the time (three reader average); the majority being cases of a suspected CT abnormality found to be normal on US. Ultrasound changed the diagnosis for the uterus 11.9% of the time (three reader average); the majority related to the endometrial canal. The 95% confidence intervals for the ovaries/adnexa and uterus were 5-12.5% and 8-17%, respectively. Ten cases of a normal CT were followed by a normal US with 100% agreement across all three readers. Experienced readers correctly diagnosed ruptured ovarian cysts and tubo-ovarian abscesses (TOA) based on CT alone with 100% agreement. US reimaging after MDCT of the abdomen and pelvis is not helpful: (1) following a normal CT of the pelvic organs or (2) when CT findings are diagnostic and/or characteristic of certain entities such as ruptured cysts and TOA. Reimaging with ultrasound is warranted for (1) less-experienced readers to improve diagnostic confidence or when CT findings are not definitive, (2) further evaluation of suspected endometrial abnormalities. A distinction should be made between the need for immediate vs. follow-up imaging with US after CT

OBJECTIVE:: To compare free-breathing radially sampled 3D fat suppressed T1-weighted gradient-echo acquisitions (radial volumetric interpolated breath-hold examination [VIBE]) with breath-hold (BH) and free-breathing conventional (rectilinearly sampled k-space) VIBE acquisitions for postcontrast imaging of the liver. MATERIALS AND METHODS:: Eighteen consecutive patients referred for clinically indicated liver magnetic resonance imaging were imaged at 3 T. Three minutes after a single dose of gadolinium contrast injection, free-breathing radial VIBE, BH VIBE, and free-breathing VIBE with 4 averages were acquired in random order with matching sequence parameters. Radial VIBE was acquired with the 'stack-of-stars' scheme, which uses conventional sampling in the slice direction and radial sampling in-plane.All image data sets were evaluated independently by 3 radiologists blinded to patient and sequence information. Each reader scored the following parameters: overall image quality, respiratory motion artifact, pulsation artifact, liver edge sharpness, and hepatic vessel clarity using a 5-point scale, with the highest score indicating the most optimum examination. Mixed model analysis of variance was used to compare sequences in terms of each measure of image quality. RESULTS:: When scores were averaged over readers, there was no statistically significant difference between radial VIBE and BH VIBE regarding overall image quality (P = 0.1015), respiratory motion artifact (P = 1.0), and liver edge sharpness (P = 0.2955). Radial VIBE demonstrated significantly lower pulsation artifact (P < 0.0001), but had lower hepatic vessel clarity (P = 0.0176), when compared with BH VIBE. Radial VIBE had significantly higher image quality scores for all parameters when compared with free-breathing VIBE (P < 0.0001). Acquisition time for BH VIBE was 14 seconds and that of free-breathing radial VIBE and conventional VIBE with multiple averages was 56 seconds each. CONCLUSION:: Radial VIBE can be performed during free breathing for contrast-enhanced imaging of the liver with comparable image quality to BH VIBE. However, further work is necessary to shorten the acquisition time to perform dynamic imaging