Utility of CT Radiomics Features in Differentiation of Pancreatic Ductal Adenocarcinoma From Normal Pancreatic Tissue.

OBJECTIVE. The objective of our study was to determine the utility of radiomics features in differentiating CT cases of pancreatic ductal adenocarcinoma (PDAC) from normal pancreas. MATERIALS AND METHODS. In this retrospective case-control study, 190 patients with PDAC (97 men, 93 women; mean age ± SD, 66 ± 9 years) from 2012 to 2017 and 190 healthy potential renal donors (96 men, 94 women; mean age ± SD, 52 ± 8 years) without known pancreatic disease from 2005 to 2009 were identified from radiology and pathology databases. The 3D volume of the pancreas was manually segmented from the preoperative CT scans by four trained researchers and verified by three abdominal radiologists. Four hundred seventy-eight radiomics features were extracted to express the phenotype of the pancreas. Forty features were selected for analysis because of redundancy of computed features. The dataset was divided into 255 training cases (125 normal control cases and 130 PDAC cases) and 125 validation cases (65 normal control cases and 60 PDAC cases). A random forest classifier was used for binary classification of PDAC versus normal pancreas of control cases. Accuracy, sensitivity, and specificity were calculated. RESULTS. Mean tumor size was 4.1 ± 1.7 (SD) cm. The overall accuracy of the random forest binary classification was 99.2% (124/125), and AUC was 99.9%. All PDAC cases (60/60) were correctly classified. One case from a renal donor was misclassified as PDAC (1/65). The sensitivity was 100%, and specificity was 98.5%. CONCLUSION. Radiomics features extracted from whole pancreas can be used to differentiate between CT cases from patients with PDAC and healthy control subjects with normal pancreas.

Brief Report: Interleukin-17A-Dependent Asymmetric Stem Cell Divisions Are Increased in Human Psoriasis: A Mechanism Underlying Benign Hyperproliferation.

The balance between asymmetric and symmetric stem cell (SC) divisions is key to tissue homeostasis, and dysregulation of this balance has been shown in cancers. We hypothesized that the balance between asymmetric cell divisions (ACDs) and symmetric cell divisions (SCDs) would be dysregulated in the benign hyperproliferation of psoriasis. We found that, while SCDs were increased in squamous cell carcinoma (SCC) (human and murine), ACDs were increased in the benign hyperproliferation of psoriasis (human and murine). Furthermore, while sonic hedgehog (linked to human cancer) and pifithrinα (p53 inhibitor) promoted SCDs, interleukin (IL)-1α and amphiregulin (associated with benign epidermal hyperproliferation) promoted ACDs. While there was dysregulation of the ACD:SCD ratio, no change in SC frequency was detected in epidermis from psoriasis patients, or in human keratinocytes treated with IL-1α or amphiregulin. We investigated the mechanism whereby immune alterations of psoriasis result in ACDs. IL17 inhibitors are effective new therapies for psoriasis. We found that IL17A increased ACDs in human keratinocytes. Additionally, studies in the imiquimod-induced psoriasis-like mouse model revealed that ACDs in psoriasis are IL17A-dependent. In summary, our studies suggest an association between benign hyperproliferation and increased ACDs. This work begins to elucidate the mechanisms by which immune alteration can induce keratinocyte hyperproliferation. Altogether, this work affirms that a finely tuned balance of ACDs and SCDs is important and that manipulating this balance may constitute an effective treatment strategy for hyperproliferative diseases. Stem Cells 2017;35:2001-2007.

Case 218: Birt-Hogg-Dubé syndrome.

History A 53-year-old man presented to the emergency department with subacute poorly localized abdominal pain that was increasing in intensity. He had a history of spontaneous pneumothoraces and skin lesion biopsy. Clinical examination revealed numerous small dome-shaped flesh-colored papules on the head and neck, as well as multiple palpable soft pliable nontender subcutaneous tumors scattered over the chest, abdomen, and extremities. Laboratory test results were unremarkable. The patient underwent contrast material-enhanced multidetector computed tomography (CT) of the chest, abdomen, and pelvis after intravenous administration of 120 mL of iohexol (Omnipaque 350; GE Healthcare, Princeton, NJ) infused at a rate of 3 mL/sec.

CT colonography for the detection of nonpolypoid adenomas: sensitivity assessed with restricted national CT colonography trial criteria.

OBJECTIVE: The purpose of this study was to determine the prevalence of nonpolypoid adenomas and the sensitivity of CT colonography (CTC) in their detection by use of the restricted criteria of height-to-width ratio<50% and height elevation≤3 mm. MATERIALS AND METHODS: In the National CT Colonography Trial (American College of Radiology Imaging Network protocol 6664), a cohort of 2531 participants without symptoms underwent CTC and screening colonoscopy. The CTC examinations were interpreted with both 2D and 3D techniques. Nonpolypoid adenomatous polyps identified with CTC or colonoscopy were retrospectively reviewed to determine which polyps met the restricted criteria. The prevalence of nonpolypoid adenomas and the prospective sensitivity of CTC were determined. Descriptive statistics were used to report the prevalence, size, and histologic features. The sensitivities (with 95% CIs) for nonpolypoid and polypoid lesions were compared by two-sided Z test for independent binomial proportions. RESULTS: The retrospective review confirmed 21 nonpolypoid adenomas, yielding a prevalence of 0.83% (21 of 2531 participants). Eight (38.1%) were advanced adenomas, many (50% [4/8]) only because of large size (≥10 mm). The overall per polyp sensitivity of CTC (combined 2D and 3D interpretation) for detecting nonpolypoid adenomas≥5 mm (n=21) was 0.76; ≥6 mm (n=16), 0.75; and ≥10 mm (n=5), 0.80. These values were not statistically different from the sensitivity of detecting polypoid adenomas (p>0.37). CONCLUSION: In this large screening population, nonpolypoid adenomas had a very low prevalence (<1%), and advanced pathologic features were uncommon in polyps<10 mm in diameter. Most nonpolypoid adenomas are technically visible at CTC. The prospective sensitivity is similar to that for polypoid adenomas when the interpretation combines both 2D and 3D review.

Pneumatosis and portal venous gas: do CT findings reassure?

BACKGROUND: Small, single-institution studies have suggested risk factors for bowel ischemia/necrosis (I/N) in patients with computed tomography (CT) findings of pneumatosis (PN) and portal venous gas (PVG). Here, analysis has been expanded in a large, multicenter study. MATERIALS & METHODS: Logistic regression models and receiver operating characteristic curves were used to construct a scoring system for I/N in cases of PN/PVG. RESULTS: Of 265 patients with PN/PVG identified, 209 had adequate data. In unadjusted analyses the following variables were significantly associated with I/N: age, peritoneal signs, ascites, the presence of both PVG and PN, blood urea nitrogen (BUN), CO2, albumin, and a history of hypertension, myocardial infarction, or stroke. In contrast, the CT findings of mesenteric stranding, bowel-wall thickening, and type of PN were not associated with I/N. In adjusted analyses, three variables were significantly associated with I/N: age ≥60 y (odds ratio = 2.51, 95% confidence interval: 1.26-4.97), peritoneal signs (10.58, 4.23-26.4), and BUN >25 mg/dL (3.08, 1.54-6.17), whereas presence of both PN and PVG (versus only one) was associated with an increase (but not statistically significant increase) in odds (2.01, 0.94-4.36). Although several ad hoc models were used to maximize diagnostic ability, with maximal odds ratio = 174, the areas of receiver operating characteristic curves were all below 0.80, revealing suboptimal accuracy to diagnose I/N. CONCLUSIONS: Older age, peritoneal signs, and high BUN are associated with I/N, suggesting an ability to predict which patients need operation. CT findings traditionally suggestive of ischemic PN/PVG, however, do not diagnose I/N accurately enough to reliably identify patients needing operation.

MDCT and CT angiography evaluation of rectal bleeding: the role of volume visualization.

OBJECTIVE: This article reviews several different causes of rectal bleeding and the role of MDCT in diagnosis. CONCLUSION: Although colonoscopy remains the first-line modality for the diagnosis of lower gastrointestinal tract bleeding, colonoscopy may not be possible for unstable patients, and moreover, even for patients who undergo colonoscopy, the examination may still fail to diagnose a cause for bleeding. MDCT with CT angiography and 3D mapping now offers a valuable option for diagnosis, not only for patients whose colonoscopy findings were negative, but also as a first-line screening modality for patients with active bleeding and hemodynamic instability. This article reviews the valuable role of MDCT in the diagnosis of multiple different causes of rectal bleeding, including rectal vascular malformations, rectal varices, ischemic colitis, stercoral colitis, inflammatory bowel disease, radiation proctopathy, infectious colitis, and rectal cancer.

MDCT evaluation of ureteral tumors: advantages of 3D reconstruction and volume visualization.

OBJECTIVE: This article reviews the use of CT urography in diagnosing ureteral transitional cell carcinomas, different CT urography protocols, CT findings suggestive of ureteral malignancy, and the importance of 3D reconstructions. CONCLUSION: The ureters can be problematic to evaluate on CT, partly because of difficulties in obtaining adequate ureteral distention and opacification. Proper diagnosis hinges not only on appropriate interpretation of the axial images but also on the utilization of a 3D technique (volume rendering or maximum intensity projection) as an ancillary tool.

CT after pancreaticoduodenectomy: spectrum of normal findings and complications.

OBJECTIVE: The purpose of this article is to discuss the normal findings and complications after pancreaticoduodenectomy. The Whipple procedure is associated with a set of common complications, including pancreatic fistula, postsurgical hemorrhage, postoperative pancreatitis, portomesenteric venous thrombosis, hepatic infarction, delayed gastric emptying, and anastomotic strictures. CONCLUSION: Appropriate diagnosis of these complications is contingent on an understanding of the surgical anatomy, normal postoperative imaging appearance in both the immediate postoperative and chronic settings, and typical CT appearance of each of these complications.

Informatics in radiology: CT contrast protocols application for the iPad: new resource for technologists, nurses, and radiologists.

The iPad, iPhone, and other portable devices offer a unique opportunity for radiology education, allowing presentation of information in a simple, concise, and mobile fashion to large groups of learners. The CT Contrast Protocols application for the iPad and iPhone is one of the first radiology applications in the Apple App Store to focus on radiology education and was designed to address the lack of practical information on contrast media for radiologists, technologists, nurses, and trainees. The application was developed in response to questions about contrast media use from clinicians, technologists, and nurses; its content is based on questions from these members of the authors' department and hospital, as well as users of the CTisus.com Web site. The application uses a simple interface that requires no training and can be easily navigated by those who have only recently begun using an iPad or iPhone. It provides simple, easily understood answers to many common questions about contrast media use, all arranged under several subject headings. The application is constantly evolving and represents an aggregate of the knowledge found in the literature, the American College of Radiology's consensus guidelines, and the institutional practices of the computed tomography division of Johns Hopkins Hospital. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg.333125106/-/DC1.

Sclerosing angiomatoid nodular transformation of the spleen (SANT): multimodality imaging appearance of five cases with radiology-pathology correlation.

OBJECTIVE: Sclerosing angiomatoid nodular transformation (SANT) is an extremely rare splenic lesion first reported in 2004, representing an unusual reaction of splenic red pulp to stromal inflammation or vascular injury. There are very few descriptions of the imaging appearance of SANT in the literature. We present five pathologically proven cases of SANT, with a description of the imaging appearance using multiple different modalities, as well as correlation with the histopathologic features of the lesion. CONCLUSION: While there are several imaging features of SANT which have been described in the literature, it is not routinely possible to make a prospective diagnosis based on the imaging features alone. Moreover, it may not be possible to exclude malignancy based on the imaging features, and splenectomy may be required in certain cases.

Incidentally detected cystic lesions of the pancreas on CT: review of literature and management suggestions.

PURPOSE: To facilitate a better understanding of incidentally noted cystic pancreatic lesions, since these lesions often pose a challenge regarding appropriate management. METHODS: This article reviews pathophysiology, prevalence, significance, and recommendations for management of the various pancreatic cystic lesions. Illustrative cases are demonstrated. RESULTS: Diagnostic benign lesions can be left alone. Cross-sectional imaging can be used to follow-up benign appearing lesions and to stage more aggressive ones. Endoscopic ultrasound with fine needle aspiration and cyst fluid analysis can be performed on certain indeterminate lesions. Lesions with high malignant potential should undergo resection. CONCLUSIONS: A better understanding of the variety of incidentally detected pancreatic cystic lesions can help direct appropriate management.

Thalidomide for the treatment of cough in idiopathic pulmonary fibrosis: a randomized trial.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a progressive, fatal disorder of unknown cause with no effective treatment. Cough affects up to 80% of patients with IPF, is frequently disabling, and lacks effective therapy. OBJECTIVE: To determine the efficacy of thalidomide in suppressing cough in patients with IPF. DESIGN: 24-week, double-blind, 2-treatment, 2-period crossover trial. (ClinicalTrials.gov registration number: NCT00600028) SETTING: 1 university center. PARTICIPANTS: 98 participants were screened, 24 were randomly assigned, 23 received treatment (78.3% men; mean age, 67.6 years; mean FVC, 70.4% predicted), and 20 completed both treatment periods. MEASUREMENTS: The primary end point was cough-specific quality of life measured by the Cough Quality of Life Questionnaire (CQLQ). Secondary end points were visual analogue scale of cough and the St. George's Respiratory Questionnaire (SGRQ). For all measures, lower scores equaled improved cough or respiratory quality of life. RESULTS: CQLQ scores significantly improved with thalidomide (mean difference vs. placebo, -11.4 [95% CI, -15.7 to -7.0]; P < 0.001). Thalidomide also significantly improved scores on the visual analogue scale of cough (mean difference vs. placebo, -31.2 [CI, -45.2 to -17.2]; P < 0.001). In participants receiving thalidomide, scores from the total SGRQ, SGRQ symptom domain, and SGRQ impact domain improved compared with those of participants receiving placebo. Adverse events were reported in 74% of patients receiving thalidomide and 22% receiving placebo; constipation, dizziness, and malaise were more frequent with thalidomide. LIMITATION: This was a single-center study of short duration and small sample size focused on symptom-specific quality of life. CONCLUSION: Thalidomide improved cough and respiratory quality of life in patients with IPF. A larger trial is warranted to assess these promising results. PRIMARY FUNDING SOURCE: Celgene Corporation.

Portal vein aneurysms: imaging manifestations and clinical significance.

This article will review the computed tomography (CT) findings in patients with portal vein aneurysms (including presentation of several case examples) and discuss imaging criteria and management options. Given the extreme rarity of portal vein aneurysms, as well as a lack of familiarity with the entity on the part of radiologists, the diagnosis can often be overlooked. Appreciation of the most commonly used diagnostic criteria, as well as the role of CT in the appropriate follow-up of these patients, is critical in ensuring appropriate management. In particular, the significance of these aneurysms must be appreciated in the emergency setting, as portal vein aneurysms can rarely present with symptoms of abdominal pain and other complications (such as thrombosis, portal hypertension, rupture, embolism, and compression of the duodenum and inferior vena cava) making surgical repair necessary.

Clinicopathological characteristics and molecular analyses of multifocal intraductal papillary mucinous neoplasms of the pancreas.

OBJECTIVE: To examine the clinicopathologic features and clonal relationship of multifocal intraductal papillary mucinous neoplasms (IPMNs) of the pancreas. BACKGROUND: Intraductal papillary mucinous neoplasms are increasingly diagnosed cystic precursor lesions of pancreatic cancer. Intraductal papillary mucinous neoplasms can be multifocal and a potential cause of recurrence after partial pancreatectomy. METHODS: Thirty four patients with histologically documented multifocal IPMNs were collected and their clinicopathologic features catalogued. In addition, thirty multifocal IPMNs arising in 13 patients from 3 hospitals were subjected to laser microdissection followed by KRAS pyrosequencing and loss of heterozygosity (LOH) analysis on chromosomes 6q and 17p. Finally, we sought to assess the clonal relationships among multifocal IPMNs. RESULTS: We identified 34 patients with histologically documented multifocal IPMNs. Synchronous IPMNs were present in 29 patients (85%), whereas 5 (15%) developed clinically significant metachronous IPMNs. Six patients (18%) had a history of familial pancreatic cancer. A majority of multifocal IPMNs (86% synchronous, 100% metachronous) were composed of branch duct lesions, and typically demonstrated a gastric-foveolar subtype epithelium with low or intermediate grades of dysplasia. Three synchronous IPMNs (10%) had an associated invasive cancer. Molecular analysis of multiple IPMNs from 13 patients demonstrated nonoverlapping KRAS gene mutations in 8 patients (62%) and discordant LOH profiles in 7 patients (54%); independent genetic alterations were established in 9 of the 13 patients (69%). CONCLUSIONS: The majority of multifocal IPMNs arise independently and exhibit a gastric-foveolar subtype, with low to intermediate dysplasia. These findings underscore the importance of life-long follow-up after resection for an IPMN.

The National CT Colonography Trial: assessment of accuracy in participants 65 years of age and older.

PURPOSE: To conduct post-hoc analysis of National CT Colonography Trial data and compare the sensitivity and specificity of computed tomographic (CT) colonography in participants younger than 65 years with those in participants aged 65 years and older. MATERIALS AND METHODS: Of 2600 asymptomatic participants recruited at 15 centers for the trial, 497 were 65 years of age or older. Approval of this HIPAA-compliant study was obtained from the institutional review board of each site, and informed consent was obtained from each subject. Radiologists certified in CT colonography reported lesions 5 mm in diameter or larger. Screening detection of large (≥10-mm) histologically confirmed colorectal neoplasia was the primary end point; screening detection of smaller (6-9-mm) colorectal neoplasia was a secondary end point. The differences in sensitivity and specificity of CT colonography in the two age cohorts (age < 65 years and age ≥ 65 years) were estimated with bootstrap confidence intervals (CIs). RESULTS: Complete data were available for 477 participants 65 years of age or older (among 2531 evaluable participants). Prevalence of adenomas 1 cm or larger for the older participants versus the younger participants was 6.9% (33 of 477) versus 3.7% (76 of 2054) (P < .004). For large neoplasms, mean estimates for CT colonography sensitivity and specificity among the older cohort were 0.82 (95% CI: 0.644, 0.944) and 0.83 (95% CI: 0.779, 0.883), respectively. For large neoplasms in the younger group, CT colonography sensitivity and specificity were 0.92 (95% CI: 0.837, 0.967) and 0.86 (95% CI: 0.816, 0.899), respectively. Per-polyp sensitivity for large neoplasms for the older and younger populations was 0.75 (95% CI: 0.578, 0.869) and 0.84 (95% CI: 0.717, 0.924), respectively. For the older and younger groups, per-participant sensitivity was 0.72 (95% CI: 0.565, 0.854) and 0.81 (95% CI: 0.745, 0.882) for detecting adenomas 6 mm in diameter or larger. CONCLUSION: For most measures of diagnostic performance and in most subsets, the difference between senior-aged participants and those younger than 65 years was not statistically significant.

Transitional cell carcinoma of the upper urinary tract: optimizing image interpretation with 3D reconstructions.

PURPOSE: This article reviews the pathophysiology of transitional cell carcinoma (TCC), CT urography (CTU) protocols, different possible 3D reconstruction techniques, and the importance of 3D reconstructions for appropriate interpretation. RESULTS/CONCLUSION: CTU has largely replaced conventional IV pyelography in the evaluation of the upper urinary tract for TCC. The majority of large lesions can be easily seen on standard axial images with multiplanar reformats. However, it is imperative to also use 3D reconstructions when interpreting these studies, as subtle lesions can be difficult to visualize on the more traditional images. In this pictorial essay, we present multiple cases of upper urinary tract TCC which illustrate the value of 3D reconstructions for increasing the conspicuity of lesions, particularly at the junction of the infundibulum and calyx and in the ureters. As these cases demonstrate, each of the three possible 3D reconstruction techniques (maximum intensity projection, volume rendering, and volume rendered "virtual ureteroscopy") has its own distinct advantages, although the pitfalls of each technique must also be kept in mind.

Superior mesenteric artery syndrome: spectrum of CT findings with multiplanar reconstructions and 3-D imaging.

OBJECTIVE: This article reviews the causes, clinical presentation, and CT diagnosis of superior mesenteric artery (SMA) syndrome. CONCLUSION: In conjunction with an appropriate clinical history, several CT findings can suggest the diagnosis of SMA syndrome. These findings include narrowing of the aortomesenteric angle and distance, distension of the stomach and duodenum, and dilatation of the left renal vein with left-sided venous collaterals.

The iPad as a mobile device for CT display and interpretation: diagnostic accuracy for identification of pulmonary embolism.

Recent software developments enable interactive, real-time axial, 2D and 3D CT display on an iPad by cloud computing from a server for remote rendering. The purpose of this study was to compare radiologists' interpretative performance on the iPad to interpretation on the conventional picture archive and communication system (PACS). Fifty de-identified contrast-enhanced CT exams performed for suspected pulmonary embolism were compiled as an educational tool to prepare our residents for night call. Two junior radiology attendings blindly interpreted the cases twice, one reader used the PACS first, and the other interpreted on the iPad first. After an interval of at least 2 weeks, the cases were reinterpreted in different order using the other display technique. Sensitivity, specificity, and accuracy for identification of pulmonary embolism were compared for each interpretation method. Pulmonary embolism was present in 25 patients, ranging from main pulmonary artery to subsegmental thrombi. Both readers interpreted 98 % of cases correctly regardless of display platform. There was no significant difference in sensitivity (98 vs 100 %, p = 1.0), specificity (98 vs 96 %, p = 1.0), or accuracy (98 vs 98 %, p = 1.0) for interpretation with the iPad vs the PACS, respectively. CT interpretation on an iPad enabled accurate identification of pulmonary embolism, equivalent to display on the PACS. This mobile device has the potential to expand radiologists' availability for consultation and expedite emergency patient management.

CT of acute abdominopelvic hemorrhage: protocols, pearls, and pitfalls.

Abdominal and pelvic hemorrhage may be secondary to a number of causes and is often a medical emergency. Patient presentation ranges from obvious trauma with evidence of hemodynamic instability to vague symptoms. CT has become the imaging modality of choice for identifying abdominopelvic hemorrhage. Recognizing acute hemorrhage as well as identifying its location and severity are key to expediting management. In the Emergency Department, ultrasound often used in the initial evaluation of trauma patients, but is not sensitive for subtle bleeds or injuries. CT is the best first-line imaging tool to identify abdominal hemorrhage and, compared with angiography, has been shown to be superior in detecting intra-abdominal bleeding, especially when the bleeding rate is low. Depending on location and etiology, abdominopelvic hemorrhage may have a characteristic appearance, such as the "sentinel clot" sign associated with blunt trauma to the solid organs or the "triangle sign" of a mesenteric bleed. The following pictorial essay reviews CT technique, study interpretation, and interpretative pearls and pitfalls in the recognition of acute abdominopelvic hemorrhage.

Accuracy of CT colonography for detection of large adenomas and cancers.

BACKGROUND: Computed tomographic (CT) colonography is a noninvasive option in screening for colorectal cancer. However, its accuracy as a screening tool in asymptomatic adults has not been well defined. METHODS: We recruited 2600 asymptomatic study participants, 50 years of age or older, at 15 study centers. CT colonographic images were acquired with the use of standard bowel preparation, stool and fluid tagging, mechanical insufflation, and multidetector-row CT scanners (with 16 or more rows). Radiologists trained in CT colonography reported all lesions measuring 5 mm or more in diameter. Optical colonoscopy and histologic review were performed according to established clinical protocols at each center and served as the reference standard. The primary end point was detection by CT colonography of histologically confirmed large adenomas and adenocarcinomas (10 mm in diameter or larger) that had been detected by colonoscopy; detection of smaller colorectal lesions (6 to 9 mm in diameter) was also evaluated. RESULTS: Complete data were available for 2531 participants (97%). For large adenomas and cancers, the mean (+/-SE) per-patient estimates of the sensitivity, specificity, positive and negative predictive values, and area under the receiver-operating-characteristic curve for CT colonography were 0.90+/-0.03, 0.86+/-0.02, 0.23+/-0.02, 0.99+/-<0.01, and 0.89+/-0.02, respectively. The sensitivity of 0.90 (i.e., 90%) indicates that CT colonography failed to detect a lesion measuring 10 mm or more in diameter in 10% of patients. The per-polyp sensitivity for large adenomas or cancers was 0.84+/-0.04. The per-patient sensitivity for detecting adenomas that were 6 mm or more in diameter was 0.78. CONCLUSIONS: In this study of asymptomatic adults, CT colonographic screening identified 90% of subjects with adenomas or cancers measuring 10 mm or more in diameter. These findings augment published data on the role of CT colonography in screening patients with an average risk of colorectal cancer. (ClinicalTrials.gov number, NCT00084929; American College of Radiology Imaging Network [ACRIN] number, 6664.)