Purpose:To investigate whether a dual inversion-recovery (IR) prepulse improves scar-to-blood contrast and expert confidence and consistency at late gadolinium-enhanced magnetic resonance (MR) imaging of myocardial scar compared with the standard IR technique at 3.0 T.Materials and Methods:The study was approved by the local ethics committee, and all patients provided written informed consent. Twelve men (mean age ± standard deviation, 63 years ± 8) with known myocardial scar underwent MR imaging 10, 20, and 30 minutes after administration of 0.2 mmol/kg gadobutrol with a standard and dual IR sequence. Contrast-to-noise ratios (CNRs) were measured by using region-of-interest analysis, and data were compared with the analysis of variance test. Two experts measured scar size and transmurality, and data were compared with the Student t test and Bland-Altman test. Experts assigned confidence scores for scar detection and transmurality, which were compared with a Wilcoxon matched-pairs signed rank test.Results:Patient data showed improved scar-to-blood CNR for the dual IR technique compared with the standard IR technique at all time points (P <.05). For images obtained 20 minutes after contrast material administration, the dual IR sequence provided higher confidence scores for scar detection and transmurality assessment (P <.05) and resulted in more consistent assessment of scar size and transmurality between readers compared with the IR sequence (P <.05).Conclusion:In this preliminary patient study, the dual IR prepulse improved contrast, scar visualization, and expert confidence and reduced expert differences in transmurality and scar size assessment compared with the standard IR technique.©RSNA, 2012Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12112004/-/DC1.

Purpose:To prospectively assess the accuracy of contrast agent-enhanced (CE) ultrasonography (US) with a second-generation US contrast agent in the detection and classification of endoleaks after endovascular repair of abdominal aortic aneurysms (EVAR), with computed tomographic (CT) angiography as the reference standard.Materials and Methods:Institutional review board and written informed consent were obtained. Thirty-five patients who underwent EVAR were enrolled in a prospective study that consisted of CT angiography and CE US studies performed at 1- and 6-month follow-up and performed yearly thereafter. CE US was performed after bolus injection of 2.4 mL of sulfur hexafluoride by using equipment with specific software for contrast studies. Angiography was performed in patients who had type II endoleaks with an increase in aneurysm sac size and in patients with type I or III endoleaks. CE US sensitivity, specificity, positive and negative predictive values, and accuracy were determined for endoleak detection, and Cohen κ statistic was used to assess agreement of CE US and CT angiographic findings for endoleak classification.Results:A total of 126 CT angiographic and CE US studies were performed. CT angiography depicted 34 endoleaks in 16 patients (type IA, n = 1; type IB, n = 1; type II inferior mesenteric artery, n = 2; type II lumbar artery, n = 28; type II complex, inferior mesenteric, and lumbar arteries, n = 2). CE US depicted 33 endoleaks. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of CE US in endoleak detection were 97%, 100%, 100%, 98%, and 99%, respectively. CE US enabled correct classification of 26 of 33 endoleaks. No clinically important endoleak was missed at CE US.Conclusion:CE US yields good sensitivity, specificity, and accuracy in endoleak detection, and it might represent a noninvasive tool that can be used in the follow-up of patients who undergo EVAR.©RSNA, 2012Supplemental material:http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12111528/-/DC1.

Purpose:To evaluate the positive predictive values (PPVs) of Breast Imaging and Reporting Data Systems (BI-RADS) assessment categories for breast magnetic resonance (MR) imaging and to identify the BI-RADS MR imaging lesion features most predictive of cancer.Materials and Methods:This institutional review board-approved HIPAA-compliant prospective multicenter study was performed with written informed consent. Breast MR imaging studies of the contralateral breast in women with a recent diagnosis of breast cancer were prospectively evaluated. Contralateral breast MR imaging BI-RADS assessment categories, morphologic descriptors for foci, masses, non-masslike enhancement (NMLE), and kinetic features were assessed for predictive values for malignancy. PPV of each imaging characteristic of interest was estimated, and logistic regression analysis was used to examine the predictive ability of combinations of characteristics.Results:Of 969 participants, 71.3% had a BI-RADS category 1 or 2 assessment; 10.9%, a BI-RADS category 3 assessment; 10.0%, a BI-RADS category 4 or 5 assessment; and 7.7%, a BI-RADS category 0 assessment on the basis of initial MR images. Thirty-one cancers were detected with MR imaging. Overall PPV for BI-RADS category 4 and 5 lesions was 0.278, with 17 cancers in patients with a BI-RADS category 4 lesion (PPV, 0.205) and 10 cancers in patients with a BI-RADS category 5 lesion (PPV, 0.714). Of the cancers, one was a focus, 17 were masses, and 13 were NMLEs. For masses, irregular shape, irregular margins, spiculated margins, and marked internal enhancement were most predictive of malignancy. For NMLEs, ductal, clumped, and reticular or dendritic enhancement were the features most frequently seen with malignancy. Kinetic enhancement features were less predictive of malignancy than were morphologic features.Conclusion:Standardized terminology of the BI-RADS lexicon enables quantification of the likelihood of malignancy for MR imaging-detected lesions through careful evaluation of lesion features. In particular, BI-RADS assessment categories and morphologic descriptors for masses and NMLE were useful in estimating the probability of cancer.© RSNA, 2012.

Purpose:To evaluate the effect of gadoxetate disodium on fibrosis in a rat model of active hepatic fibrosis.Materials and Methods:The local committee for animal research approved this study. Hepatic fibrosis was induced during 12 weeks of intraperitoneal injection of carbon tetrachloride (CCl(4)). Gadoxetate disodium was administered at 10 mmol/kg for 5 consecutive days starting after the final dose of CCl(4)(clinical dose of gadoxetate disodium is 0.25 mmol/kg). Three groups of Sprague-Dawley rats were studied. Group 1 consisted of six rats treated only with gadoxetate disodium, group 2 consisted of nine rats treated only with CCl(4), and group 3 consisted of nine rats treated with both gadoxetate disodium and CCl(4). Seven days after the final injection of gadoxetate disodium, the rats were sacrificed, and histologic findings and gadolinium deposition in the liver were examined. Fibrosis stage and gadolinium deposition were compared by using the Mann-Whitney test and Student t test.Results:Fibrosis grading in groups 2 and 3 did not differ significantly (mean Batts-Ludwig fibrosis stage in group 2 was 2.67 and in group 3 was 2.78, P =.70; mean Ishak fibrosis stage in group 2 was 3.89 and in group 3 was 4.11, P =.71). Gadolinium deposition in the liver was slightly increased in group 3 in comparison to group 1 (3.2 ppm versus 4.0 ppm, P =.01), although this reversed when corrected as a percentage of total injected dose (0.022% versus 0.017%, P =.003).Conclusion:The high-dose administration of gadoxetate disodium in the setting of active hepatic fibrosis was not associated with increased fibrosis, suggesting that gadoxetate disodium does not incite a nephrogenic systemic fibrosis-like fibrotic change in the setting of active hepatic inflammation.© RSNA, 2012.

Purpose:To retrospectively determine which features of urinary calculi are associated with their detection after virtual elimination of contrast medium at dual-energy computed tomographic (CT) urography by using a novel tin filter.Materials and Methods:The institutional ethics committee approved this retrospective study, with waiver of informed consent. A total of 152 patients were examined with single-energy nonenhanced CT and dual-energy CT urography in the excretory phase (either 140 and 80 kV [n = 44] or 140 and 100 kV [n = 108], with tin filtration at 140 kV). The contrast medium in the renal pelvis and ureters was virtually removed from excretory phase images by using postprocessing software, resulting in virtual nonenhanced (VNE) images. The sensitivity regarding the detection of calculi on VNE images compared with true nonenhanced (TNE) images was determined, and interrater agreement was evaluated by using the Cohen k test. By using logistic regression, the influences of image noise, attenuation, and stone size, as well as attenuation of the contrast medium, on the stone detection rate were assessed. Threshold values with maximal sensitivity and specificity were calculated by means of receiver operating characteristic analyses.Results:Eighty-seven stones were detected on TNE images; 46 calculi were identified on VNE images (sensitivity, 52.9%). Interrater agreement revealed a k value of 0.95 with TNE images and 0.91 with VNE data. Size (long-axis diameter, P =.005; short-axis diameter, P =.041) and attenuation (P =.0005) of the calculi and image noise (P =.0031) were significantly associated with the detection rate on VNE images. As threshold values, size larger than 2.9 mm, maximum attenuation of the calculi greater than 387 HU, and image noise less than 20 HU were found.Conclusion:After virtual elimination of contrast medium, large (>2.9 mm) and high-attenuation (>387 HU) calculi can be detected with good reliability; smaller and lower attenuation calculi might be erased from images, especially with increased image noise.© RSNA, 2012.

Purpose:To evaluate prospectively the performance of noncalcium images reconstructed from dual-energy (DE) computed tomography (CT) for the diagnosis of bone marrow lesions in patients with acute ankle joint trauma in comparison with magnetic resonance (MR) images.Materials and Methods:The study had local ethics board approval, and written informed consent was obtained. Thirty consecutive patients (15 women; mean age, 34 years ± 11.8 [standard deviation]) underwent dual-source DE CT (80 kVp and 140 kVp with tin filter) and MR imaging within 1 day following acute ankle trauma. DE CT data were postprocessed by using a three-material decomposition algorithm for generating noncalcium images. MR and noncalcium images were graded by two blinded, independent readers using a four-point system (1 = distinct bone marrow lesion, 4 = no lesion); CT numbers in noncalcium images were calculated by a third reader. MR imaging interpretations served as the reference standard.Results:Interreader agreement for qualitative grading of DE CT images was substantial (κ = 0.66). The respective sensitivity, specificity, positive predictive value, and negative predictive value of DE CT for depicting distinct bone marrow lesions for both readers were 90.0% each, 80.5% and 81.6%, 25.4% and 26.5%, and 99.1% each. In regions without abnormality, CT numbers in noncalcium images gradually increased from proximal to distal location (P <.001). Significant differences in CT numbers were found in regions positive for bone marrow lesions compared with those that were negative (P <.001). CT numbers for the diagnosis of distinct bone marrow lesions according to MR imaging revealed areas under the receiver operating characteristic curve of 0.973, 0.813, and 0.758 for ankle mortise, talar dome, and talar body/head, respectively.Conclusion:Compared with MR images, distinct traumatic bone marrow lesions of the ankle joint can be diagnosed on noncalcium images reconstructed from DE CT with high sensitivity and excellent negative predictive value, but with moderate specificity and low positive predictive value.© RSNA, 2012.

Purpose:To determine the potential of minimally invasive postmortem computed tomographic (CT) angiography combined with image-guided tissue biopsy of the myocardium and lungs in decedents who were thought to have died of acute chest disease and to compare this method with conventional autopsy as the reference standard.Materials and Methods:The responsible justice department and ethics committee approved this study. Twenty corpses (four female corpses and 16 male corpses; age range, 15-80 years), all of whom were reported to have had antemortem acute chest pain, were imaged with postmortem whole-body CT angiography and underwent standardized image-guided biopsy. The standard included three biopsies of the myocardium and a single biopsy of bilateral central lung tissue. Additional biopsies of pulmonary clots for differentiation of pulmonary embolism and postmortem organized thrombus were performed after initial analysis of the cross-sectional images. Subsequent traditional autopsy with sampling of histologic specimens was performed in all cases. Thereafter, conventional histologic and autopsy reports were compared with postmortem CT angiography and CT-guided biopsy findings. A Cohen k coefficient analysis was performed to explore the effect of the clustered nature of the data.Results:In 19 of the 20 cadavers, findings at postmortem CT angiography in combination with CT-guided biopsy validated the cause of death found at traditional autopsy. In one cadaver, early myocardial infarction of the papillary muscles had been missed. The Cohen κ coefficient was 0.94. There were four instances of pulmonary embolism, three aortic dissections (Stanford type A), three myocardial infarctions, three instances of fresh coronary thrombosis, three cases of obstructive coronary artery disease, one ruptured ulcer of the ascending aorta, one ruptured aneurysm of the right subclavian artery, one case of myocarditis, and one pulmonary malignancy with pulmonary artery erosion. In seven of 20 cadavers, CT-guided biopsy provided additional histopathologic information that substantiated the final diagnosis of the cause of death.Conclusion:Postmortem CT angiography combined with image-guided biopsy, because of their minimally invasive nature, have a potential role in the detection of the cause of death after acute chest pain.© RSNA, 2012.

Purpose:To assess the feasibility of diffusional kurtosis (DK) imaging for distinguishing benign from malignant regions, as well as low- from high-grade malignant regions, within the peripheral zone (PZ) of the prostate in comparison with standard diffusion-weighted (DW) imaging.Materials and Methods:The institutional review board approved this retrospective HIPAA-compliant study and waived informed consent. Forty-seven patients with prostate cancer underwent 3-T magnetic resonance imaging by using a pelvic phased-array coil and DW imaging (maximum b value, 2000 sec/mm(2)). Parametric maps were obtained for apparent diffusion coefficient (ADC); the metric DK (K), which represents non-Gaussian diffusion behavior; and corrected diffusion (D) that accounts for this non-Gaussianity. Two radiologists reviewed these maps and measured ADC, D, and K in sextants positive for cancer at biopsy. Data were analyzed by using mixed-model analysis of variance and receiver operating characteristic curves.Results:Seventy sextants exhibited a Gleason score of 6; 51 exhibited a Gleason score of 7 or 8. K was significantly greater in cancerous sextants than in benign PZ (0.96 ± 0.24 vs 0.57 ± 0.07, P <.001), as well as in cancerous sextants with higher rather than lower Gleason score (1.05 ± 0.26 vs 0.89 ± 0.20, P <.001). K showed significantly greater sensitivity for differentiating cancerous sextants from benign PZ than ADC or D (93.3% vs 78.5% and 83.5%, respectively; P <.001), with equal specificity (95.7%, P >.99). K exhibited significantly greater sensitivity for differentiating sextants with low- and high-grade cancer than ADC or D (68.6% vs 51.0% and 49.0%, respectively; P ≤ .004) but with decreased specificity (70.0% vs 81.4% and 82.9%, respectively; P ≤ .023). K had significantly greater area under the curve for differentiating sextants with low- and high-grade cancer than ADC (0.70 vs 0.62, P =.010). Relative contrast between cancerous sextants and benign PZ was significantly greater for D or K than ADC (0.25 ± 0.14 and 0.24 ± 0.13, respectively, vs 0.18 ± 0.10; P <.001).Conclusion:Preliminary findings suggest increased value for DK imaging compared with standard DW imaging in prostate cancer assessment.© RSNA, 2012Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12112290/-/DC1.

Purpose:To develop a list of radiologic criteria for describing lumbar spinal stenosis, to learn from experts which parameters they consider to be most important, and to assess the strength of agreement among experts on the most relevant criteria.Materials and Methods:An expert panel of 41 radiologists (musculoskeletal experts and neuroradiologists from Europe and the United States) was formed. A three-round Delphi survey was conducted. Twenty-seven of the 41 nominated experts agreed to participate; 21 completed all three rounds. In the first round, experts were asked to complete a list of suggested parameters and cutoff values to describe lumbar spinal stenosis. In the second round, panelists rated the diagnostic relevance of each parameter (visual analog scale, 0-10). In the third round, panelists were provided with the group results (median and range) and their own answers and had the opportunity to adapt their judgments from round 2. To assess the degree of consensus among experts, the Cronbach α was calculated.Results:The qualitative criteria disk protrusion and perineural intraforaminal fat were rated as the most important diagnostic indicators, with median scores of 9 (range, 2-10). The highest rated quantitative criterion was the anteroposterior diameter of the osseous canal, with a median score of 8; however, there was a wide range of scores (range, 0-10). The median Cronbach α of all panelists within the group was 0.81 after the third round.Conclusion:Results of the survey suggest that there are no broadly accepted quantitative criteria and only partially accepted qualitative criteria for the diagnosis of lumbar spinal stenosis. The latter include disk protrusion, lack of perineural intraforaminal fat, hypertrophic facet joint degeneration, absent fluid around the cauda equine, and hypertrophy of the ligamentum flavum.© RSNA, 2012Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12111930/-/DC1.

Purpose:To evaluate initial radiologic findings of symptomatic intracranial vertebrobasilar dissections (VBDs) as well as the results at follow-up imaging of dissections that are conservatively managed.Materials and Methods:The respective institutional review boards approved this retrospective study and waived the need for informed consent. The initial radiologic findings of 210 patients with 230 symptomatic intracranial VBDs were retrospectively evaluated (48 ruptured, 182 unruptured). Those patients had undergone conventional angiography as well as magnetic resonance imaging and/or computed tomographic angiography, so that angiographic shapes and pathognomonic findings (eg, intramural hematoma, intimal flap) could be reviewed. The primary angiographic shapes of the symptomatic intracranial VBDs were subdivided into three groups:(a) dilatation without stenosis,(b) pearl-and-string, and (c) stenosis without dilatation. Furthermore, the radiologic evolution of conservatively managed symptomatic intracranial VBDs was evaluated. The respective frequencies of the radiologic findings at initial and follow-up imaging studies were compared by using χ(2) tests.Results:Primary shape differed significantly between ruptured and unruptured symptomatic intracranial VBDs. Most ruptured dissections presented with one of two main structures: dilatation without stenosis or pearl-and-string appearance. The primary shape of unruptured dissections was evenly distributed among the three types of findings. Intramural hematomas were most frequently found in the stenosis-without-dilatation group (42 of 60 [70%]), followed by the pearl-and-string group (27 of 90 [30%]). Intimal flap was most frequently found in the pearl-and-string group (21 of 90 [23%]), followed by the stenosis-without-dilatation group (eight of 60 [13%]). Follow-up results significantly differed by initial VBD shapes: Seventy-four percent (25 of 34) of the dilatation-without-stenosis group showed no change, whereas improvement was observed in 91%(39 of 43) of the stenosis-without-dilatation group (P <.05). Intracranial VBDs with intramural hematoma showed improvement in 63%(34 of 54) of cases, progression occurred in 20%(11 of 54), and only 17%(nine of 54) exhibited no change (P <.05).Conclusion:Primary angiographic shapes of symptomatic intracranial VBDs differed between ruptured and unruptured lesions. The stenosis-without-dilatation lesions most frequently exhibited radiologic improvement at follow-up imaging, followed by pearl-and-string and dilatation-without-stenosis lesions.© RSNA, 2012.

Purpose:To determine the incidence and risk factors of immediate hypersensitivity reactions to gadolinium-based magnetic resonance (MR) contrast agents.Materials and Methods:Institutional review board approval and a waiver of informed consent were obtained. A retrospective study of patients who had been given gadolinium-based MR contrast media between August 2004 and July 2010 was performed by reviewing their electronic medical records. In addition to data on immediate hypersensitivity reaction, the kinds of MR contrast media and demographic data including age, sex, and comorbidity were collected. To compare the groups, the χ(2) test, Fisher exact test, χ(2) test for trend, Student t test, analysis of variance test, and multiple logistic regression test were performed.Results:A total of 112 immediate hypersensitivity reactions (0.079% of 141 623 total doses) were identified in 102 patients (0.121% of 84 367 total patients). Among the six evaluated MR contrast media, gadodiamide had the lowest rate (0.013%) of immediate hypersensitivity reactions, while gadobenate dimeglumine had the highest rate (0.22%). The rate for immediate hypersensitivity reactions was significantly higher in female patients (odds ratio = 1.687; 95% confidence interval: 1.143, 2.491) and in patients with allergies and asthma (odds ratio = 2.829; 95% confidence interval: 1.427, 5.610). Patients with a previous history of immediate hypersensitivity reactions had a higher rate of recurrence after reexposure to MR contrast media (30%) compared with the incidence rate in total patients (P <.0001). The incidence of immediate hypersensitivity reactions increased depending on the number of times patients were exposed to MR contrast media (P for trend =.036). The most common symptom was urticaria (91.1%), and anaphylaxis occurred in 11 cases (9.8%). The mortality rate was 0.0007% because of one fatality.Conclusion:The incidence of immediate hypersensitivity reactions to MR contrast media was 0.079%, and the recurrence rate of hypersensitivity reactions was 30% in patients with previous reactions.© RSNA, 2012Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12112025/-/DC1.

Purpose:To evaluate operator radiation exposure during percutaneous interventions on hemodialysis arteriovenous fistulas (AVFs) and arteriovenous grafts (AVGs).Materials and Methods:Seventy-seven procedures were performed in 57 patients while the interventional radiologist wore two ring dosimeters, two thermoluminescent dosimeters at the lower legs, and a thermoluminescent dosimeter on the forehead. Dose-area product, fluoroscopy time, total procedure time, and radiation exposures to eye lens, hands, and legs were recorded. Variables were procedure type, access site side, and angiography equipment. Statistical analysis was performed with the signed-rank and Mann-Whitney U tests.Results:Mean operator radiation doses for the left hand, right hand, eye lens, left leg, and right leg were 0.28, 0.28, 0.03, 0.11, and 0.12 mSv, respectively. Radiation exposure to the hands was significantly higher compared with that to the legs (P <.0001). In recanalization procedures, fluoroscopy time, total procedure time, and mean number of angiographic runs were higher (all P <.001) than those for percutaneous transluminal angioplasty (PTA), as were radiation exposures to the hands and left leg (all P <.05). Left-sided access interventions resulted in higher doses to the right hand and leg (both P <.05). For right-sided access interventions, doses to the left hand and leg were higher (P <.0001). Eye lens radiation dose was significantly higher for procedures with the flat-panel detector system (P =.002).Conclusion:Operator radiation exposure to the hands, legs, and eyes during percutaneous interventional procedures performed on hemodialysis AVFs and AVGs is relatively low. Radiation exposure to the hands was higher than that to the legs, and the hand and leg closest to the AVF or AVG received a higher dose. Recanalization procedures resulted in higher doses to the hands and left leg than did PTA. Eye lens radiation dose may be higher with a flat-panel detector system.©RSNA, 2012.

Purpose:To evaluate use of imaging in children with acute abdominal pain who present to U.S. emergency departments (EDs).Materials and Methods:This study received expedited review by the institutional review board. The National Hospital Ambulatory Medical Care Survey is a government-administered yearly survey of EDs that is used to estimate ED care throughout the United States. This retrospective cohort study interrogated the database for the period from 1999 to 2007. Univariate regression analysis was performed, and a multivariate regression model was developed.Results:From 1999 to 2007, 16 900 000 pediatric ED visits were made for acute abdominal pain. Odds of undergoing computed tomography (CT) in this population increased during each year of the study period. No significant changes occurred in use of ultrasonography, number of patients admitted to the hospital, or number of patients with acute appendicitis. A multivariate model for CT use revealed increased odds of CT use in teens, white patients, the Midwest region, urban settings, patients with private insurance, and patients who were admitted or transferred. Odds of undergoing CT were significantly lower among patients who presented to a pediatric-focused emergency department (adjusted odds ratio, 0.72; 95% confidence interval: 0.58, 0.90).Conclusion:The main findings of this study are that the rate of CT use in the evaluation of abdominal pain in children increased every year between 1999 and 2007 and that the use of CT was greater among children seen in adult-focused EDs. Factors affecting CT use include sex, race, age, insurance status, and geographic region.© RSNA, 2012.

Purpose:To ascertain the effects of the payment reductions in the Deficit Reduction Act (DRA), which affected only in-office imaging, on the utilization of noninvasive musculoskeletal imaging.Materials and Methods:This study of nonidentifiable aggregate data did not require institutional review board approval. Medicare Part B Physician/Supplier Procedure Summary Files for 2004, 2006, and 2008 were used. By using descriptive statistics and weighted linear regression, all 111 relevant procedure codes were evaluated to measure the effect of the DRA's payment reductions on change in utilization growth rate between the pre-DRA (2004-2006) and post-DRA (2006-2008) periods.Results:Overall, between the pre-DRA and post-DRA periods, the type of imaging studied demonstrated a 2% deceleration (reduction in per capita utilization growth rate) in the office and a 0.7% deceleration in the outpatient hospital setting. However, nonradiologist and radiologist utilization were both still growing, particularly for nonradiographic imaging. In the office, for both nonradiologists and radiologists, larger DRA payment reductions were associated with greater deceleration; deceleration was approximately 0.2% greater for each additional 1% of reimbursement reduction. There was no payment-reduction-size-related acceleration in the outpatient setting.Conclusion:The growth rate of in-office noninvasive musculoskeletal imaging performed by nonradiologists and the growth rate of this type of imaging being referred to radiologists decreased in the period following the implementation of the DRA. Nonetheless, after the DRA, in-office nonradiographic noninvasive musculoskeletal imaging performed by nonradiologists was still growing much more rapidly than that performed by radiologists.© RSNA, 2012.

Purpose:To compare the apparent diffusion coefficients (ADCs) of pancreatic adenocarcinomas that appear hyperintense with clearly defined borders (clear hyperintense) with those that do not show clear hyperintense borders on diffusion-weighted magnetic resonance (MR) images.Materials and Methods:Institutional review board approval was obtained and informed consent was waived. Eighty patients with histologically confirmed pancreatic adenocarcinoma (mean tumor size, 32 mm) underwent fat-suppressed single-shot echo-planar 3.0-T diffusion-weighted MR imaging with diffusion gradients (b = 1000 sec/mm(2)). ADC values of the pancreatic adenocarcinomas (n = 80) and proximal (n = 51) and distal (n = 70) pancreas were compared by using the Friedman test, followed by the Wilcoxon signed-rank test, and the difference in serum amylase levels between pancreatic adenocarcinomas with and without clear hyperintensity was evaluated by using the x(2) test.Results:In 38 of 80 patients, pancreatic adenocarcinomas showed clear hyperintensity relative to the surrounding pancreas; 26 were hyperintense with unclear distal borders; 12, isointense; and four, hypointense. In all patients, the mean ADC (± standard deviation) of the tumors (1.16 × 10(-3) mm(2)/sec ± 0.22) was significantly lower than those of the proximal pancreas (1.33 × 10(-3) mm(2)/sec ± 0.16, P <.001) and the distal pancreatic parenchyma (1.24 × 10(-3) mm(2)/sec ± 0.23, P =.004). No significant difference in ADC was seen between the pancreatic adenocarcinomas without clear hyperintensity and the distal pancreas. The frequency of serum amylase levels greater than 120 U/L (2.00 μkat/L) was significantly higher than in those with clear hyperintense pancreatic adenocarcinomas (P <.001).Conclusion:Diffusion-weighted MR imaging was not useful for delineating 47% of pancreatic adenocarcinomas, because of hyperintensity of the pancreatic parenchyma distal to the cancer.© RSNA, 2012.

Purpose:To investigate the use of diffusion-weighted (DW) imaging for differentiating benign lesions from malignant pleural disease (MPD) and to retrospectively assess dynamic contrast material-enhanced (DCE) magnetic resonance (MR) imaging acquisitions to find out whether combining these measurements with DW imaging could improve the diagnostic value of DW imaging.Materials and Methods:This study was approved by the local ethics committee, and all patients provided written informed consent. Thirty-one consecutive patients with pleural abnormalities suspicious for MPD underwent whole-body positron emission tomography (PET)/computed tomography (CT) and thorax MR examinations. Diagnostic thoracoscopy with histopathologic analysis of pleural biopsies served as the reference standard. First-line evaluation of each suspicious lesion was performed by using the apparent diffusion coefficient (ADC) calculated from the DW image, and the optimal cutoff value was found by using receiver operating characteristic curve analysis. Afterward, DCE MR imaging data were used to improve the diagnosis in the range of ADCs where DW imaging results were equivocal.Results:Sensitivity, specificity, and accuracy of PET/CT for diagnosis of MPD were 100%, 35.3%, and 64.5%. The optimal ADC threshold to differentiate benign lesions from MPD with DW MR imaging was 1.52 × 10(-3) mm(2)/sec, with sensitivity, specificity, and accuracy of 71.4%, 100%, and 87.1%, respectively. This result could be improved to 92.8%, 94.1%, and 93.5%, respectively, when DCE MR imaging data were included in those cases where ADC was between 1.52 and 2.00 × 10(-3) mm(2)/sec. A total of 20 patients had disease diagnosed correctly, nine had disease diagnosed incorrectly, and two cases were undetermined with PET/CT. DW imaging helped stage disease correctly in 27 patients and incorrectly in four. The undetermined cases at PET/CT were correctly diagnosed at MR imaging.Conclusion:DW imaging is a promising tool for differentiating MPD from benign lesions, with high accuracy, and supplementation with DCE MR imaging seems to further improve sensitivity.© RSNA, 2012Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12110872/-/DC1.

Purpose:To evaluate the incidence of contrast material-induced nephropathy (CIN) in patients with an estimated glomerular filtration rate (eGFR) of less than 60 mL/min/1.73 m(2) who received intravenous contrast media and underwent treatment in accordance with current guidelines and to determine risk factors associated with CIN.Materials and Methods:The research ethics committee waived the requirement for informed consent for this prospective cohort study. All nonhospitalized patients with an eGFR of less than 60 mL/min/1.73 m(2) were seen at a special outpatient clinic. Patients were stratified for the risk of CIN. They were classified as having high or low risk for CIN on the basis of absolute glomerular filtration rate (Modification of Diet in Renal Disease formula result multiplied by body surface area divided by 1.73 m(2)) and the presence of risk factors. Patients at high risk were hydrated with 1000 mL of isotonic saline before and after contrast material exposure. Serum creatinine level was measured 3-5 days later, and CIN was defined as an increase of 25% of more from the baseline level. Risk factors were recorded and compared between patients with CIN and those without CIN by using forward stepwise multiple logistic regression analysis.Results:A total of 944 procedures in 747 patients were evaluated. Mean age was 71.3 years ± 10 (standard deviation), and 42.9% of patients were female. In 511 procedures (54.1%), patients were hydrated. CIN developed after 23 procedures (2.4%). No patient needed hemodialysis treatment. Heart failure (odds ratio, 3.0), body mass index (BMI)(odds ratio, 0.9), and repeated contrast material administration (odds ratio, 2.8) were found to be independent predictors of CIN.Conclusion:Heart failure, low BMI, and repeated contrast material administration were identified as risk factors for CIN under the current treatment strategy. The low incidence of CIN supports the use of hydration as a preventive measure in patients at high risk for CIN.© RSNA, 2012Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12111667/-/DC1.

Purpose:To assess the reproducibility and the distribution of intravoxel incoherent motion (IVIM) and diffusion-tensor (DT) imaging parameters in healthy renal cortex and medulla at baseline and after hydration or furosemide challenges.Materials and Methods:Using an institutional review board-approved HIPAA-compliant protocol with written informed consent, IVIM and DT imaging were performed at 3 T in 10 volunteers before and after water loading or furosemide administration. IVIM (apparent diffusion coefficient [ADC], tissue diffusivity [D(t)], perfusion fraction [f(p)], pseudodiffusivity [D(p)]) and DT (mean diffusivity [MD], fractional anisotropy [FA], eigenvalues [λ(i)]) imaging parameters and urine output from serial bladder volumes were calculated.(a) Reproducibility was quantified with coefficient of variation, intraclass correlation coefficient, and Bland-Altman limits of agreement;(b) contrast and challenge response were quantified with analysis of variance; and (c) Pearson correlations were quantified with urine output.Results:Good reproducibility was found for ADC, D(t), MD, FA, and λ(i)(average coefficient of variation, 3.7%[cortex] and 5.0%[medulla]), and moderate reproducibility was found for D(p), f(p), and f(p) · D(p)(average coefficient of variation, 18.7%[cortex] and 25.9%[medulla]). Baseline cortical diffusivities significantly exceeded medullary values except D(p), for which medullary values significantly exceeded cortical values, and λ(1,) which showed no contrast. ADC, D(t), MD, and λ(i) increased significantly for both challenges. Medullary diffusivity increases were dominated by transverse diffusion (1.72 ± 0.09 [baseline] to 1.79 ± 0.10 [hydration] μm(2)/msec, P =.0059; or 1.86 ± 0.07 [furosemide] μm(2)/msec, P =.0094). Urine output correlated with cortical ADC with furosemide (r = 0.7, P =.034) and with medullary λ(1)(r = 0.83, P =.0418), λ(2)(r = 0.85, P =.0301), and MD (r = 0.82, P =.045) with hydration.Conclusion:Diffusion MR metrics are sensitive to flow changes in kidney induced by diuretic challenges. The results of this study suggest that vascular flow, tubular dilation, water reabsorption, and intratubular flow all play important roles in diffusion-weighted imaging contrast.© RSNA, 2012.

Purpose:To evaluate liver stiffness (LS) and spleen stiffness (SS) in patients with extrahepatic portal vein obstruction (EHPVO).Materials and Methods:Institutional research board approval and informed consent were obtained. LS and SS were measured in 65 consecutive patients with EHPVO. Patients underwent endoscopy, liver biopsy, liver function tests, abdominal ultrasonography, a detailed history, and examination. LS and SS measurements were also obtained in 50 age-matched healthy control subjects. Comparisons were made by using the Student t test, Mann-Whitney test for quantitative data, and χ(2) or Fisher exact test for qualitative data.Results:Sixty-five patients with EHPVO (with a bleed, n = 45; without a bleed, n = 20; mean age, 25.4 years ± 10.7 [standard deviation]; 29 men, 36 women) were enrolled. Twenty-two (34%) had hypersplenism. LS (P =.001) and SS (P =.01) were higher in patients with EHPVO (6.7 kPa ± 2.3 and 51.7 kPa ± 21.5, respectively) than in control subjects (4.6 kPa ± 0.7 and 16.0 kPa ± 3.0, respectively). Patients who had a bleed had higher SS than did those without a bleed (60.4 kPa ± 5.4 vs 30.3 kPa ± 14.2, P =.01). There was no significant difference in age (26.7 years ± 10.4 vs 22.5 years ± 9.8, P =.8) and median duration of disease (4.5 years [range, 1-26 years] vs 6.0 years [range, 1-22 years], P =.23) in patients with a bleed versus those without. With a cutoff of 5.9 kPa for LS, sensitivity and specificity for detection of a variceal bleed were 67% and 75%, respectively. An SS cutoff of 42.8 kPa yielded sensitivity and specificity of 88% and 94%, respectively.Conclusion:LS and SS were higher in patients with EHPVO than in control subjects, and patients with a history of a bleed had a higher SS than did those without a bleed.© RSNA, 2011.

Purpose:To prospectively compare findings of magnetic resonance (MR) lymphangiography with those of lymphoscintigraphy, evaluate the pattern and delay of lymphatic drainage, compare typical findings, and investigate discrepancies between the techniques.Materials and Methods:This prospective study was performed according to the Declaration of Helsinki and was approved by the local ethics committee. Thirty consecutive patients with uni- or bilateral lymphedema and lymph vessel transplants of the lower extremities were examined with 3.0-T fat-saturated three-dimensional gradient-echo MR after gadopentetate dimeglumine injection. Results of all examinations were correlated with corresponding results of lymphoscintigraphy examinations. Results of both techniques were separately reviewed in consensus by a radiologist and a nuclear physician, who rated delay and pattern of drainage, number of enhancing levels, and quality of conspicuity of the depiction of lymph nodes and lymph vessels. Sensitivity and specificity were calculated by using combined results of both techniques and clinical presentation findings as reference standard. Correlation was calculated with weighted κ coefficients.Results:Weak lymphatic drainage at lymphoscintigraphy correlated with lymphangiectasia at MR lymphangiography (13 of 33 affected extremities). Lymph vessels were clearly visualized with MR lymphangiography (five of 24 affected extremities), while they were not detectable with lymphoscintigraphy. Depiction of inguinal lymph nodes was clearer with lymphoscintigraphy (five of 60 extremities). Correlation of both techniques was excellent for delay (κ = 0.93) and pattern (κ = 0.84) of drainage, good for depiction of lymph nodes (κ = 0.67) and number of enhancing levels (κ = 0.77), and moderate for depiction of lymph vessels (κ = 0.50). Sensitivity and specificity for delay and pattern of drainage were concordant, whereas MR lymphangiography showed a higher sensitivity for lymph vessel abnormalities (100% vs 79%) and lower specificity for lymph node abnormalities (78% vs 100%).Conclusion:Imaging findings of MR lymphangiography and lymphoscintigraphy show a clear concordance. With lymphoscintigraphy, better visualization of inguinal lymph nodes was achieved, whereas with MR lymphangiography, better depiction of lymph vessels and morphologic features of lymph vessel abnormalities were achieved.© RSNA, 2012Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12110229/-/DC1.