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The concept of a software-defined radio (SDR), capable of reconfiguring its signal processing to meet situational demands, was introduced in literature over 30 years ago. At the time, systems were held back due to hardware limitations and the fact that computation was expensive. Since the inception of SDR, significant technological improvements have been made, driving the cost of SDR systems down to the point where the flexibility they provide far outweighs their price tag. In this paper, we introduce the design specification and capability of a proven SDR system dubbed the Communications Experimentation, Low-cost, Lightweight Software defined radio Test Bed (CELLS Test Bed). In addition, we provide example applications which demonstrate the wide-array of applications to which the CELLS Test Bed can be applied.

Objective Our aim in this study was to evaluate the effect of the radiologist, technologist, and other examination-related factors on the frequency of recommendations for additional imaging (RAI) during sonographic (US) interpretation. Methods We retrospectively reviewed 719 US reports from a single academic medical center for the presence of RAI. All studies had been interpreted by one of three abdominal radiologists. Examinations were performed at an outpatient radiology facility with no onsite radiologist (n = 299) or at an inpatient emergency department or hospital-based outpatient setting that had an onsite radiologist (n = 420). Possible associations between the frequency of RAI and the presence of an onsite radiologist, location of the examination, body part or region imaged, patient age, technologist performing the exam, and radiologist reading the exam were evaluated. Results There were significant differences between each pair of radiologists in terms of overall frequency of RAI (p

Pancreatic ductal adenocarcinoma is an aggressive malignancy with a high mortality rate. Proper determination of the extent of disease on imaging studies at the time of staging is one of the most important steps in optimal patient management. Given the variability in expertise and definition of disease extent among different practitioners as well as frequent lack of complete reporting of pertinent imaging findings at radiologic examinations, adoption of a standardized template for radiology reporting, using universally accepted and agreed on terminology for solid pancreatic neoplasms, is needed. A consensus statement describing a standardized reporting template authored by a multi-institutional group of experts in pancreatic ductal adenocarcinoma that included radiologists, gastroenterologists, and hepatopancreatobiliary surgeons was developed under the joint sponsorship of the Society of Abdominal Radiologists and the American Pancreatic Association. Adoption of this standardized imaging reporting template should improve the decision-making process for the management of patients with pancreatic ductal adenocarcinoma by providing a complete, pertinent, and accurate reporting of disease staging to optimize treatment recommendations that can be offered to the patient. Standardization can also help to facilitate research and clinical trial design by using appropriate and consistent staging by means of resectability status, thus allowing for comparison of results among different institutions.

Purpose To evaluate the stand-alone performance of a computer-aided detection (CAD) algorithm for colorectal polyps in a large heterogeneous CT colonography (CTC) database that included both tagged and untagged datasets. Methods Written, informed consent was waived for this institutional review board-approved, HIPAA-compliant retrospective study. CTC datasets from 2063 patients were assigned to training (n = 374) and testing (n = 1689). The test set consisted of 836 untagged and 853 tagged examinations not used for CAD training. Examinations were performed at 15 sites in the United States, Asia, and Europe, using 4- to 64-multidetector-row computed tomography and various acquisition parameters. CAD sensitivities were calculated on a per-patient and per-polyp basis for polyps measuring ≥6 mm. The reference standard was colonoscopy in 1588 (94%) and consensus interpretation by expert radiologists in 101 (6%) patients. Statistical testing employed χ, logistic regression, and Mann-Whitney U tests. Results In 383 of 1689 individuals, 564 polyps measuring ≥6 mm were identified by the reference standard (347 polyps: 6-9 mm and 217 polyps: ≥10 mm). Overall, CAD per-patient sensitivity was 89.6% (343/383), with 89.0% (187/210) for untagged and 90.2% (156/173) for tagged datasets (P = 0.72). Overall, per-polyp sensitivity was 86.9% (490/564), with 84.4% (270/320) for untagged and 90.2% (220/244) for tagged examinations (P = 068). The mean false-positive rate per patient was 5.14 (median, 4) in untagged and 4.67 (median, 4) in tagged patient datasets (P = 0.353). Conclusion Stand-alone CAD can be applied to both tagged and untagged CTC studies without significant performance differences. Detection rates are comparable to human readers at a relatively low false-positive rate, making CAD a useful tool in clinical practice.

The introduction of dual-energy computed tomography systems (ie, scanners that can simultaneously acquire images at different energies) has significant and unique applications for urologists. Imaging data from these scanners can be used to evaluate composition of urinary calculi and, by "removing" iodine from an image, significantly decrease radiation dose to patients referred for hematuria. Further, the ability to create a virtual noncontrast image obviates the need for repeated scanning in patients with incidentally detected renal and adrenal masses. Finally, the ability to quantify the regional concentration of iodine in a renal neoplasm may provide a method to monitor effectiveness of therapy before size changes become apparent.

The purpose of this study is to investigate the clinical and CT findings in patients with symptomatic colonoscopy-induced splenic rupture, and to assess for common features among this cohort. Multi-center search yielded 11 adults with symptomatic splenic injury related to colonoscopy. Workup included abdominal CT in 10 (91%) cases and abdominal radiography in two patients (one patient had both). Colonoscopy findings, post-procedural course, and CT findings were systematically reviewed. Mean patient age was 62.2 years (range, 51-84 years); 8 (73%) of 11 were female. The majority (64%) of colonoscopies were for screening. No immediate complications were reported at optical colonoscopy; tortuosity/redundancy was noted in five cases. Except for a small (8 mm) polyp in one case and a large (10 mm) polyp in another, the remaining nine patients had either diminutive or no polyps. Only one patient presented with hemodynamic instability during post-colonoscopy recovery; the other ten had a delayed presentation ranging from 8 h to 8 days (mean, 2.1 days). All 11 patients presented with abdominal pain. CT was diagnostic for splenic injury with subcaspular and/or perisplenic hematoma in all ten CT cases. Hemoperitoneum was present in eight, visible splenic laceration in three cases, and splenic artery pseudoaneurysm in one case. Five patients underwent splenectomy (four emergent) and six patients were treated conservatively. Average hospital stay was 5.5 days (range, 3-10 days). Colonoscopy-induced splenic rupture characteristically presents as a delayed and often serious complication. In cases of apparent non-traumatic splenic hematoma or rupture at CT, eliciting a history of recent colonoscopy may identify the etiology.

To retrospectively evaluate the frequency of recommendations for additional imaging (RAIs) for important extracolonic findings and polyp prevalence among a cohort of seniors (age ≥ 65 years) and nonseniors (age65 years) undergoing low-dose computed tomographic (CT) colonography.Institutional review board approval was obtained for this HIPAA-compliant retrospective study. Four hundred fifty-four patients (204 nonseniors: mean age, 52 years; 250 seniors: mean age, 69 years) underwent CT colonography at an outpatient facility. Cases were prospectively reported by one of four abdominal radiologists with expertise in CT colonography. The dictated reports were reviewed to determine the frequency of polyps (≥6 mm), the number of extracolonic findings, and the number of RAIs generated. The Fisher exact test was used to compare the percentage of seniors and nonseniors with at least one reported polyp, with at least one extracolonic finding, as well as the frequency of RAIs.The percentage of patients with at least one reported polyp was 14.2% (29 of 204) for the nonsenior group and 13.2% (33 of 250) for seniors, which was not significantly different (P = .772). The percentage of patients with at least one extracolonic finding was 55.4% (113 of 204) for nonseniors and 74.0% (185 of 250) for seniors (P.0001). The percentage of patients in which an RAI was suggested was 4.4% (nine of 204) for nonseniors and 6.0% (15 of 250) for seniors, which was not significantly different (P = .450).Extracolonic findings were more frequent in seniors than in nonseniors; however, there was no significant difference in the frequency of RAIs between the two groups.http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11102144/-/DC1.

The purpose of this study was to validate the utility of dual-source dual-energy MDCT in quantifying iodine concentration in a phantom and in renal masses.A series of tubes containing solutions of varying iodine concentration were imaged with dual-source dual-energy MDCT. Iodine concentration was calculated and compared with known iodine concentration. Single-phase contrast-enhanced dual-source dual-energy MDCT data on 15 patients with renal lesions then were assessed independently by two readers. Dual-energy postprocessing was used to generate iodine-only images. Regions of interest were placed on the iodine image over the lesion and, as a reference, over the aorta, for recording of iodine concentration in the lesion and in the aorta. Another radiologist determined lesion enhancement by comparing truly unenhanced with contrast-enhanced images. Mixed-model analysis of variance based on ranks was used to compare lesion types (simple cyst, hemorrhagic cyst, enhancing mass) in terms of lesion iodine concentration and lesion-to-aorta iodine ratio.In the phantom study, there was excellent correlation between calculated and true iodine concentration (R(2) = 0.998, p0.0001). In the patient study, 13 nonenhancing (10 simple and three hyperdense cysts) and eight enhancing renal masses were evaluated in 15 patients. The lesion iodine concentration and lesion-to-aorta iodine ratio in enhancing masses were significantly higher than in hyperdense and simple cysts (p0.0001).Iodine quantification with dual-source dual-energy MDCT is accurate in a phantom and can be used to determine the presence and concentration of iodine in a renal lesion. Characterization of renal masses may be possible with a single dual-source dual-energy MDCT acquisition without unenhanced images or reliance on a change in attenuation measurements.

To determine whether the location of the computed tomography (CT) whirl sign can be used to help differentiate caecal from sigmoid volvulus.Thirty-one patients (mean age 64.6 years) underwent multidetector CT and had confirmed colonic volvulus. There were 15 patients with caecal volvulus and 16 with sigmoid volvulus. Axial and coronal images were retrospectively evaluated on the picture archiving and communication system (PACS) by two reviewers in consensus without knowledge of the final diagnosis to determine whether a CT whirl sign was present and, if so, was the location to the right of midline or in the midline/left. The location of the twisting at imaging was correlated with whether the patient had caecal or sigmoid volvulus. Fisher's exact test was used to determine whether there was an association between the location of the twist (right versus mid-left) and the location of the colonic volvulus (caecal versus sigmoid). The non contrast CT (NCCT) examinations of 30 additional patients without colonic volvulus were evaluated for the presence or absence of a CT whirl sign.All 31 patients with colonic volvulus had a CT whirl sign. No patient who underwent NCCT for kidney stones demonstrated a CT whirl sign. According to Fisher's exact test, there was a highly significant association (p0.0001) between the location of the twist (right versus mid-left) and the location of the colonic volvulus (caecal versus sigmoid). Using the location of the twist as a predictor of whether the volvulus was caecal or sigmoid provided a correct diagnosis for 93.3% (14/15) of the patients with caecal volvulus and 100% (16/16) of those with sigmoid volvulus, yielding an overall diagnostic accuracy of 96.8% (30/31).The location of the mesenteric twist (CT whirl sign) is a highly accurate finding in discriminating caecal from sigmoid volvulus.

To compare the evaluation times and accuracy of unidirectional panoramic three-dimensional (3D) endoluminal interpretation to traditional two-dimensional (2D) and bidirectional 3D endoluminal techniques.Sixty-nine patients underwent computed tomography colonography (CTC) after bowel cleansing. Forty-five had no polyps and 24 had at least one polypor = 6 mm. Patients underwent same-day colonoscopy with segmental unblinding. Three experienced abdominal radiologists evaluated the data using one of three primary interpretation techniques: (1) 2D; (2) bidirectional 3D; (3) panoramic 3D. Mixed model analysis of variance and logistic regression for correlated data were used to compare techniques with respect to time and sensitivity and specificity.Mean evaluation times were 8.6, 14.6, and 12.1 min, for 2D, 3D, and panoramic, respectively. 2D was faster than either 3D technique (p0.0001), and the panoramic technique was faster than bidirectional 3D (p = 0.0139). The overall sensitivity of each technique per polyp and per patient was 68.4 and 76.7% for 2D, 78.9 and 93.3% for 3D; and 78.9 and 86.7% for panoramic 3D.2D interpretation was the fastest overall, the panoramic technique was significantly faster than the bidirectional with similar sensitivity and specificity. The sensitivity for a single reader was significantly lower using the 2D technique. Each reader should select the technique with which they are most successful.

The purpose of this study was to evaluate morphologic features predictive of benign thyroid nodules.From a registry of the records of 1,232 fine-needle aspiration biopsies performed jointly by the cytology and radiology departments at a single institution between 2005 and 2007, the cases of 650 patients were identified for whom both a pathology report and ultrasound images were available. From the alphabetized list generated, the first 500 nodules were reviewed. We analyzed the accuracy of individual sonographic features and of 10 discrete recognizable morphologic patterns in the prediction of benign histologic findings.We found that grouping of thyroid nodules into reproducible patterns of morphology, or pattern recognition, rather than analysis of individual sonographic features, was extremely accurate in the identification of benign nodules. Four specific patterns were identified: spongiform configuration, cyst with colloid clot, giraffe pattern, and diffuse hyperechogenicity, which had a 100% specificity for benignity. In our series, identification of nodules with one of these four patterns could have obviated more than 60% of thyroid biopsies.Recognition of specific morphologic patterns is an accurate method of identifying benign thyroid nodules that do not require cytologic evaluation. Use of this approach may substantially decrease the number of unnecessary biopsy procedures.

To evaluate the possible radiation dose reduction facilitated by using dual-energy (DE) multidetector computed tomography (CT) after endovascular repair of abdominal aortic aneurysms (AAAs).This prospective study was HIPAA compliant and institutional review board approved. Twenty-two patients who previously had undergone endovascular repair of AAAs underwent 24 DE multidetector CT examinations, which were performed with a 64-detector scanner. Initial nonenhanced CT was followed by arterial phase and venous phase acquisitions. Virtual nonenhanced, pure 80-kVp, and weighted-average peak voltage CT data sets were generated from the venous acquisition. Two independent readers interpreted the virtual nonenhanced and DE weighted-average CT data for the presence or absence of endoleaks. These interpretations were compared with the clinical interpretations of the data performed by a different radiologist by using true nonenhanced, arterial phase, and venous phase data. Region-of-interest measurements of the abdominal aorta and of the region of the endoleaks were obtained. Effective radiation dose was calculated.Both independent readers' interpretations of the virtual nonenhanced and weighted-average venous CT data revealed six type II endoleaks. There were no false-positive or false-negative findings. Aortic attenuation during the arterial, 80-kVp venous, and weighted-average data acquisitions were 288, 213, and 150 HU, respectively. The attenuation of the endoleaks was higher during the 80-kVp acquisition (P.03) than during the arterial phase and weighted-average venous phase acquisitions. The mean effective dose for DE venous phase CT was 11.1 mSv compared with 27.8 mSv for standard triple-phase CT with a single-source configuration.Preliminary observations suggest that obtaining DE multidetector CT data by using a single 60-second contrast material-enhanced acquisition may be all that is required for surveillance after endovascular repair of AAA.

Aim To determine whether epiploic appendagitis occurs in the caecum. Methods From 2000–2006, 58 cases with classic computed tomography (CT) features of acute epiploic appendagitis (focal round or oval fat density immediately adjacent to the colon with surrounding oedema and stranding, with or without a central area of high attenuation) were identified from a radiology information system and available for review on the picture archiving and communication system (PACS). Cases were assigned to one of six colonic segments: rectum, sigmoid, descending colon, transverse colon, ascending colon, and caecum. The Blyth–Still–Casella procedure was used to derive an exact upper bound on the likelihood of epiploic appendagitis occurring within the caecum. Results Twenty-eight cases occurred in the sigmoid colon, 16 in the descending colon, four in the transverse colon, and 10 in the ascending colon. No cases of acute epiploic appendagitis were identified in the caecum. Four cases of prospectively dictated caecal epiploic appendagitis were identified from the database. Retrospective review of these cases showed two cases to be epiploic appendagitis of the ascending colon. The third case demonstrated peritoneal thickening without evidence of an inflamed epiploic appendage. The fourth case was caecal diverticulitis. Based on these findings there is 95% confidence that no more than 4.6% of patients with epiploic appendagitis will show this condition within the caecum. Conclusion In the authors' experience, epiploic appendagitis does not occur in the caecum. Therefore, it is an unlikely cause for an inflammatory process in this region and other conditions should be considered.

The goal of endovascular repair of an abdominal aortic aneurysm is to exclude the aneurysm from systemic arterial pressure, thereby preventing rupture. However, the long-term durability of endovascular repair continues to be in question, as aneurysm rupture after endovascular repair continues to be reported. We report the case of an 89-year-old patient who underwent endovascular repair of a 7.1-cm abdominal aortic aneurysm with an Ancure endograft 5 years earlier. Despite close follow-up and a shrinking aneurysm sac on annual contrast-enhanced computed tomography, he presented with aneurysm rupture and a new proximal type I endoleak. The endoleak and rupture were successfully repaired with endovascular placement of a main body extension.

Racial/ethnic minorities are less likely than whites to undergo colorectal cancer (CRC) screening. Although computed tomography colonography (CTC) is a less invasive alternative to optical colonoscopy (OC), it is not known whether CTC will increase acceptance of CRC screening in minorities.Patients undergoing OC for clinically indicated reasons had CTC followed by same-day OC. After the sedation from the OC had worn off, a questionnaire was administered to assess pain, discomfort, bloating, embarrassment, anxiety, and patient satisfaction using a 10-point scale (1 = least, 10 = greatest).Of the 272 patients enrolled, there were 134 whites, 71 blacks, 53 Hispanics, and 14 who self-identified their race/ethnicity as other. Although the proportion of subjects who preferred CTC over OC was not significantly different (52.9% vs 47.1%, P = .36), racial/ethnic minorities were significantly less likely than whites to prefer CTC over OC (whites, 65.7%; blacks, 45.1%; Hispanics, 35.8%; and other, 35.7%; P.001). Racial/ethnic minorities were less satisfied with CTC (whites, 8.4 +/- 1.7; blacks, 7.8 +/- 1.7; Hispanics, 7.4 +/- 1.8; and other, 7.5 +/- 2.1; P = .001) and were significantly less willing to undergo CTC again in the future (whites, 95.5%; blacks, 80.3%; Hispanics, 84.9%; and other, 85.7%; P = .006).Compared with white patients, OC is better tolerated and is preferred over CTC for evaluation of the colon among racial/ethnic minorities. Although CTC is less invasive than OC, our findings suggest that CTC is unlikely to overcome racial/ethnic disparities in CRC screening.

OBJECTIVE. Imaging of the vast array of pathologic processes occurring in the small bowel has been facilitated by recent advances, including the use of MDCT scanners that acquire isotropic data and neutral oral contrast agents that improve small-bowel distention.CONCLUSION. This review shows how a systematic pattern approach can be used to narrow the differential diagnosis when an abnormal small-bowel loop is detected on MDCT.

To retrospectively determine if arterial phase computed tomographic (CT) imaging is necessary for follow-up imaging of patients who have undergone endovascular stent-graft therapy for abdominal aortic aneurysm.This HIPAA-compliant study was exempt from institutional review board approval; informed patient consent was waived. Eighty-five patients (66 men, 19 women; mean age, 66 years; range, 45-81 years) underwent 110 multidetector CT examinations after endovascular repair of abdominal aortic aneurysms. Nonenhanced CT images were obtained. Intravenous contrast material was then injected at 4 mL/sec, and arterial and venous phase (60 seconds) CT images were obtained. The nonenhanced and venous phase images were evaluated to determine if an endoleak was present. Subsequently, arterial phase images were analyzed. The effective dose was calculated. Ninety-five percent confidence intervals as indicators of how often arterial phase imaging would contribute to the diagnosis of endoleak were determined.Twenty-eight type II endoleaks were detected by using combined nonenhanced and venous phase acquisitions. Twenty-five of the 28 endoleaks were also visualized during the arterial phase. Three type II endoleaks were seen only during the venous phase. The arterial phase images depicted no additional endoleaks. Seventy-eight CT examinations performed in 67 patients revealed no endoleak during the venous phase. The arterial phase images also depicted no endoleaks at these examinations. Thus, for no more than 3.1% of all examinations, there was 95% confidence that arterial phase imaging would depict an endoleak missed at venous phase imaging. Arterial phase imaging contributed to a mean of 36.5% of the effective dose delivered.Study results indicate that arterial phase imaging may not be necessary for the routine detection of endoleaks. Radiation exposure can be decreased by eliminating this phase.

Endoscopically placed biliary stents have supplanted surgical decompression as the preferred treatment option for patients with obstructive jaundice from advanced pancreatic cancer. An unusual complication of indewelling biliary stents is duodenal perforation into the retroperitoneum. We describe the case of a patient with end-stage pancreatic cancer who presented with an acute abdomen from erosion of a previously placed bile duct stent through the wall of the second portion of the duodenum. Although our patient presented with advanced symptoms, clinical presentations can vary from mild abdominal discomfort and general malaise to overt septic shock. Definitive diagnosis is best made with computed tomography (CT) imaging, which can detect traces of retroperitoneal air and fluid. Treatment options vary from nonoperative management with antibiotics, bowel rest, and parenteral alimentation in the most stable patients to definitive surgery with complete diversion of gastric contents and biliary flow from the affected area in patients with clinical symptoms or radiologic evidence suggesting extensive contamination. Complications of management can include duodenal fistulization, residual retroperitoneal or intrabdominal abscess, and ongoing sepsis. This report highlights the salient issues in the presentation, diagnosis, and modern management of patients with this rare complication of indwelling biliary stents.

Computed tomographic (CT) colonography continues to evolve rapidly. Advances in scanning and display technologies, encouraging performance data, and increased utilization necessitate clarification and standardization of results reporting in CT colonography. There are several reasons for this. First and most important, standardized reporting can better assist patients and referring physicians in making management decisions on the basis of the results of CT colonography. The precedent of the mammography Breast Imaging Reporting and Data System, or BI-RADS, schema is a strong incentive to provide a similar structure for CT colonography. Second, as more examinations are performed, the likelihood increases that radiologists interpreting results of a CT colonography examination performed at one center will require comparison to examination results and reports generated at other sites. As has been seen with mammography, a common set of terms facilitates this kind of assessment (1). Third, as utilization of CT colonography increases, our colleagues in other medical specialties, the various third-party payers, and the general public will insist on larger-scale evaluations of examination performance, examination quality, patient outcome, and cost. Here again, a common approach to interpretation will assist us in meeting these demands. Finally, a common scheme for reporting facilitates structured reporting. The purpose of this communication is to facilitate clear and consistent communication of CT colonography results. The authors—an ad hoc group of investigators active in the area of CT colonography—have collaborated to develop a reporting scheme that is coupled to recommendations for follow-up. Our group, the Working Group on Virtual Colonoscopy, includes members of the American College of Radiology Colon Cancer Committee. On the basis of our collective experience and a review of the relevant literature, we present a practical guide to the interpretation of CT colonography results: the CT Colonography Reporting and Data System, or “C-RADS.” Future multidisciplinary collaboration and longitudinal data may lead to a refinement of the terms and concepts we present here; our effort is a starting point in which we attempt to address the needs of current practice. Adequate training and rigorous quality control of examination performance are essential elements for maximizing the potential of CT colonography; however, these related topics will not be discussed here. Instead, we will focus on the interpretation and follow-up of CT colonography results in three parts: first, a description of terms useful for reporting the size, morphologic features, and location of polyps and masses; second, a description of a classification scheme for colonic lesions and suggestions for follow-up; Published online 10.1148/radiol.2361041926 Radiology 2005; 236:3–9 1 From the Division of Abdominal Imaging and Intervention, Department of Radiology/ White 270, Massachusetts General Hospital, Boston, MA 02114 (M.E.Z.). The complete list of author affiliations is at the end of this article. Received November 12, 2004; accepted November 15. Address correspondence to M.E.Z. (e-mail: mzalis@partners.org).

OBJECTIVE. Stercoral colitis is an inflammatory process involving the colonic wall related to fecal impaction. Our purpose was to describe the imaging findings of stercoral colitis and ulceration and to emphasize the potential serious clinical implications of the condition.CONCLUSION. Fecal impaction may lead to ischemic pressure necrosis and subsequent colonic perforation. In the appropriate clinical setting, the imaging findings that should prompt the radiologist to consider this diagnosis are the presence of fecal impaction, focal colonic wall thickening, and adjacent stranding of the fat. If the fecal impaction is not promptly relieved, the condition can lead to colonic perforation, peritonitis, and patient demise.

Background: Duodenal diverticuli are present in up to 22% of the population. However, perforation of a duodenal diverticulum with spillage of enteric contents into the retroperitoneum is rare. Methods: We report three cases of perforated duodenal diverticulitis. Results: Clinical presentations varied widely from patients with acute abdominal findings and generalized sepsis to a patient with mild symptoms of abdominal discomfort. CT scanning was the imaging modality used to make an accurate diagnosis. Treatment approaches for the most stable patient included nonoperative management with antibiotics, bowel rest and parenteral alimentation, while the less stable patients underwent definitive surgery with complete diversion of gastric contents and biliary flow from the affected area of duodenum. Conclusions: This report highlights the salient issues in the presentation, diagnosis and modern management of patients with this potentially catastrophic disease.

Colorectal cancer is the third most common cancer in both men and women. It is estimated that in 2004, nearly 147,000 cases of colon and rectal cancer will be diagnosed in the USA, and approximately 57,000 people would die from the disease; however, only 44% of the eligible population undergoes any type of colorectal cancer screening. Many reasons have been identified for non-compliance, with key ones being patient comfort, bowel preparation and cost. Virtual colonoscopy derived from computed tomography (CT) images is gaining broader acceptance as a screening method for colorectal neoplasia. Our research suggests that computer-aided detection (CAD) as a second reader has great potential in improving polyp detection. The ColonCAD prototype presented in this paper was developed and tested on cases representative of the variability and quality in true clinical practice. Results of this study with 150 patients demonstrate that: the developed algorithm generalises well: the sensitivity for polypsor = 6 mm is on average 90%; and the median false positive rate is a manageable 3 per volume.

Early detection of colon polyps through screening has been proven to save lives, and it is expected that Computed Tomography Colonography (CTC) will offer benefits comparable to screening colonoscopy. CTC offers a more comfortable method of screening for patients, but requires significant time and effort by radiologists to examine large data sets. High-resolution images from multi-slice CT machines offer the potential to detect smaller polyps, but at the cost of larger data sets to analyze. This paper introduces and evaluates a system for rapid Computer-Aided Detection (CAD) of colon polyps, intended for use as a second reader. The system runs to completion in less time than radiologists typically require for a first read of the data. The system achieved 95% sensitivity to polyps between 6 and 19 mm in diameter, with an average of 5.76 false positives per patient.

PURPOSE: To determine the frequency with which polyps change positions with respect to the bowel surface and the cause of this movement. MATERIALS AND METHODS: From December 2001 to March 2003, 113 patients underwent computed tomographic (CT) colonography prior to colonoscopy. For all confirmed polyps that were 5 mm and larger, images obtained with CT colonography were retrospectively analyzed by one author to determine if the polyp was present on both data sets or on only one data set. Retrospective evaluation of these polyps for ventral or dorsal location within the colonic lumen was performed for data sets obtained with patients in the prone and the supine position. The data sets were further reviewed by another author to determine the cause of positional change, when present. RESULTS: Twenty-six patients had a total of 49 histologically proved colorectal polyps that were 5 mm and larger. Eight of 49 colorectal polyps were depicted only on images obtained with the patient in the supine or prone position. Of the remaining 41 polyps that were depicted on images obtained with the patient in the supine and the prone position, 11 moved from a dorsal to a ventral location or vice versa relative to the colonic surface when the patient changed position. Five of these polyps were pedunculated on a stalk. Six were sessile; two were located in the sigmoid colon, two in the transverse colon, one in the ascending colon, and one in the cecum. In these cases, polyp mobility was related to positional changes of the colon in the mesentery, as opposed to true mobility of the polyp. CONCLUSION: In this series, 27% of polyps moved from a ventral location to a dorsal location relative to the colonic surface when the patient was turned from the supine to the prone position; thus, polyps appeared to be mobile. Thus, a mobile filling defect cannot be assumed to be residual fecal material at CT colonography.

Colorectal cancer is the third most common cancer in both men and women and it was estimated that in 2003 nearly 150,000 cases would be diagnosed and 57,000 people would die. Screening has been accepted as a means for early detection of the disease, yet only a portion of the eligible population undergoes colorectal cancer screening, partially due to comfort issues of undergoing a full colonoscopic examination. Virtual colonoscopy (VC) has been demonstrated to be an effective means of performing screening and given the number of people who are candidate for screening better tools, such as Computer Aided Detection (CAD), are required to fulfill this increasing need. The developed CAD system, presented in this paper, has focused on the detection of polyps of sizes up to and including 20 mm. The results have demonstrated that: the developed algorithm generalizes, the sensitivity and specificity for middle- to large-sized polyps is on the average 95% while the overall sensitivity is roughly 88% and the false positive has remained at a manageable 4 per volume.

A variety of acute inflammatory conditions may affect the right lower quadrantprompting the patient to seek medical evaluation [1]. The clinical presentation is often confusing. The work-up of a patient with right lowerquadrant painisbased onthe clinicalhistory and physical examination, laboratory evaluation, and plain-film radiography. In patients with acute right lower quadrant pain (and abdominal pain in general), however, plain-film radiography is often noncontributory (Fig. 1) [2]. A recent study evaluating patients with abdominal pain showed that plain-film radiographywasinterpretedasnonspecificin588(68%)of871 patients, normal in 200 (23%), and abnormal in 83 (10%). In this study, abdominal radiography had 0% sensitivity for appendicitis, pyelonephritis, pancreatitis, and diverticulitis. Moreover, the clinical history and physical examination in patients with right lower quadrant pain are often nonspecific. Depending on the expertise of the treating physician, abdominal and pelvic CT is often performed to confirm if an inflammatory condition is present and to characterize it further [3]. With the widespread proliferation of multislice CT scanners in emergency departments throughout the country, this trend will likely continue [4] .I n most patients with acute right lower quadrant pain, a specificdiagnosisofappendicitiscanbemadewithCT leading to prompt surgical intervention [5,6]. Appendicitis is the most common cause of the acute abdomen particularly in young individuals. It is important for the clinician and radiologist to remember, however, that abdominal symptoms and physical signslocatedintherightlowerquadrantmaybecaused by a variety of other conditions [1,5]. In a review of

Numerous filling defects may be detected in the colon during interpretation of data sets obtained with computed tomographic (CT) colonography. A series of 230 patients were evaluated with thin-section multidetector row CT colonography immediately before conventional colonoscopy. In all cases, the interpreting radiologist and gastroenterologist reviewed the imaging findings as well as the results of histologic analysis of biopsy specimens to determine the causes of filling defects. In many cases, the cause of a filling defect can be confidently determined at CT colonography by using combinations of two- and three-dimensional images. However, lesions will occasionally be indeterminate because of overlapping features and will require further evaluation with endoscopy. With knowledge of the morphologic and attenuation characteristics of the various filling defects in the colon, one should be able to differentiate those filling defects detected at CT colonography that require no further evaluation from those that require endoscopic interrogation.

Background & Aims: No multicenter study has been reported evaluating the performance and interobserver variability of computerized tomographic colonography. The aim of this study was to assess the accuracy of computerized tomographic colonography for detecting clinically important colorectal neoplasia (polyps ≥10 mm in diameter) in a multi-institutional study. Methods: A retrospective study was developed from 341 patients who had computerized tomographic colonography and colonoscopy among 8 medical centers. Colonoscopy and pathology reports provided the standard. A random sample of 117 patients, stratified by criterion standard, was requested. Ninety-three patients were included (47% with polyps ≥10 mm; mean age, 62 years; 56% men; 84% white; 40% reported colorectal symptoms; 74% at increased risk for colorectal cancer). Eighteen radiologists blinded to the criterion standard interpreted computerized tomography colonography examinations, each using 2 of 3 different software display platforms. Results: The average area under the receiver operating characteristic curve for identifying patients with at least 1 lesion ≥10 mm was 0.80 (95% lower confidence bound, 0.74). The average sensitivity and specificity were 75% (95% lower confidence bound, 68%) and 73% (95% lower confidence bound, 66%), respectively. Per-polyp sensitivity was 75%. A trend was observed for better performance with more observer experience. There was no difference in performance across software display platforms. Conclusions: Computerized tomographic colonography performance compared favorably with reported performance of fecal occult blood testing, flexible sigmoidoscopy, and barium enema. A prospective study evaluating the performance of computerized tomography colonography in a screening population is indicated.

Using receiver-operating characteristic (ROC) methodology, the ability to diagnose acute appendicitis with computed tomography (CT) images displayed at varying levels of lossy compression was evaluated. Nine sequential images over the ileocecal region were obtained from 53 consecutive patients with right lower quadrant pain who were clinically suspected to have acute appendicitis. Thirty were proven surgically to have acute appendicitis, alternative diagnoses confirmed in 23. The image sets were subjected to a lossy wavelet-based compression algorithm "Embedded Predictive Wavelet Image Coder" (EPWIC). Compression levels were: none, 8:1, 16:1, and 24:1, resulting in 4 sets of images per patient. Image sets were randomized and evaluated separately by 4 body radiologists on a 1,024 × 768-pixel SVGA color PC monitor in 512 × 512 format. The readers were aware of the clinical suspicion of appendicitis but were unaware of the positive fraction of cases. Individual and combined reader ROC and c2 analyses of sensitivity, specificity, and accuracy were determined. For all readers, sensitivity decreases at 16:1 and 24:1 levels (P

Our aim in this study was to evaluate the effect of the radiologist, technologist, and other examination-related factors on the frequency of recommendations for additional imaging (RAI) during sonographic (US) interpretation.We retrospectively reviewed 719 US reports from a single academic medical center for the presence of RAI. All studies had been interpreted by one of three abdominal radiologists. Examinations were performed at an outpatient radiology facility with no onsite radiologist (n = 299) or at an inpatient emergency department or hospital-based outpatient setting that had an onsite radiologist (n = 420). Possible associations between the frequency of RAI and the presence of an onsite radiologist, location of the examination, body part or region imaged, patient age, technologist performing the exam, and radiologist reading the exam were evaluated.There were significant differences between each pair of radiologists in terms of overall frequency of RAI (p0.001) (radiologist 1: 12.0% [22/184]; radiologist 2: 21.6% [78/361]; and radiologist 3: 45.5% [79/174]). In addition, there were statistically significant differences in the frequency of RAI among studies scanned by the 10 different US technologists (13.6%-40.0%, p = 0.03). However, other factors such as patient age, patient sex, US unit, patient location, and radiologist location were not associated with the frequency of RAI (p = 0.15-0.93).The individual radiologist and technologist influenced the frequency of RAI for US examinations, whereas other examination-related factors did not. The observed substantial variability in RAI between radiologists and technologists warrants further study, with consideration of strategies to optimize RAI within US reports.

Background: We retrospectively reviewed the imaging features of a series of patients with cystic pancreatic masses, the majority of whom underwent imaging surveillance. Methods: Imaging data from 30 patients with known cystic pancreatic masses were reviewed. Nine patients had surgical and/or cytologic classification. Of the 21 who were not operated on, all underwent serial imaging surveillance. Of these, five had corroborative endoscopic retrograde cholangiopancreatography and 16 were followed by only computed tomography and/or magnetic resonance imaging. Results: In the nonoperated group, mean follow-up time was 30 months (3–144 months). Two patients demonstrated growth, and the remainder remain stable. In the patients who underwent surgery, invasive carcinoma was found in those with lesions larger than 4 cm, involvement of the main pancreatic duct, or visible solid components on the imaging study. Smaller lesions were benign. Conclusion: In patients with suspected cystic pancreatic neoplasms, surveillance might be possible if lesions are smaller than 2.5 cm, spare the main pancreatic duct, and demonstrate no solid components.

CT colonography is an evolving noninvasive imaging technique that allows detection of colorectal polyps and cancers. When assessing the clinical results of this test, several points need to be emphasized. First, as computed tomography (CT) technology improves, so will clinical results. Therefore, earlier results reporting the accuracy of CT colonography may not be applicable to the current state of the art. Second, as clinical experience has grown, an understanding of the limitations and pitfalls of the technique has increased. A learning curve is involved and, with increased experience, results should improve. This article will focus on the evolving clinical results of CT colonography.

In 70 patients referred for evaluation of aortoiliac aneurysm disease, multi-detector row computed tomography was performed with a uniform 25-second delay from the initiation of intravenous administration of a 150-mL bolus of contrast material at 4 mL/sec. In all patients, adequate enhancement (>200 HU) of the aorta and intense enhancement of iliofemoral runoff was achieved without venous contamination.

137 T colonography is an imaging technique that enables both two-dimensional (2D) and three-dimensional (3D) evaluation of the colon [1–3]. Although debate continues regarding which rendering technique should be used for primary evaluation, the techniques (2D and 3D) are complementary, each increasing the value of CT for colonic lumen evaluation. Two-dimensional CT colonography, when used as the primary imaging technique, may be advantageous in that data may be evaluated in a more time-efficient fashion [2, 3]. When a potential filling defect is identified on 2D CT colonography, 3D imaging is used to determine whether its morphology is linear (interhaustral fold) or polypoid (stool or polyp) [2, 3]. Three-dimensional CT colonography has the potential to visualize smaller lesions than 2D CT colonography [4]. Although some additional small lesions may be identified, evaluating CT colonography data entirely with 3D imaging is time-consuming. Moreover, often lesions are detected using 3D CT colonography that show morphology consistent with a polyp or neoplasm. When these same areas are investigated with 2D CT colonography, a variety of normal structures may be found to represent these morphologic abnormalities. Whether one uses 2D or 3D as the primary rendering method, the pitfalls on 3D imaging need to be recognized. Three-dimensional morphologic abnormalities can be divided into processes that are intrinsic or extrinsic to the colon. Our purpose is to describe the normal colon with 3D CT colonography and to show how 2D imaging can be used to establish the cause of an abnormality depicted with 3D rendering.

OBJECTIVE: Our objective was to investigate the use of CT colonography in patients who have undergone incomplete colonoscopy. CONCLUSION: CT colonography is effective in evaluating portions of the colon not seen during colonoscopy and may have an adjunctive role.

To evaluate routine non-contrast material-enhanced helical computed tomography (CT) of the adrenal glands in patients with non-small cell lung carcinoma to facilitate characterization of adrenal masses detected in an unmonitored environment (i.e., the radiologist on duty did not look at the acquired images before the patient left the scanner).One hundred consecutive patients with non-small cell lung carcinoma were referred for CT evaluation of the chest; chest and abdomen; or chest, abdomen, and brain. All underwent unenhanced CT of the adrenal glands before the requested CT examination. The morphologic features, size, and attenuation values of the adrenal masses were calculated. Attenuation values of adrenal masses from prior imaging, if available, were compared with those at follow-up imaging to classify these masses. Variable unit cost increase in obtaining these additional images was estimated.Fifteen adrenal masses were identified in 13 patients. In one patient, bilateral ill-defined adrenal masses were present. In 12 patients, 13 masses were sharply circumscribed: Seven were less than 10 HU and six were 20 HU or greater at unenhanced CT. Nine of these 12 patients received iodinated contrast material. Without the unenhanced CT, 10 adrenal masses in these nine patients would have been indeterminate for malignancy. In six of these nine patients, the adrenal mass was the only potential site of metastatic disease. The unenhanced CT data helped classify three of these masses as benign-10 HU or less- and three as indeterminate-greater than 10 HU.Unenhanced CT of the adrenal glands can prospectively characterize adrenal masses and obviate further examination in patients with lung carcinoma.

This white paper describes vascular incidental findings found on CT and MRI of the abdomen and pelvis. Recommendations for management are included. This represents the second of 4 such papers from the ACR Incidental Findings Committee II, which used a consensus method based on repeated reviews and revisions and a collective review and interpretation of relevant literature. Topics include definitions and recommended management for abdominal aortic, iliac, splenic, renal, and visceral artery aneurysms. Other incidentally discovered aortic conditions, systemic venous anomalies, compression syndromes, abdominal venous thrombosis, and gonadal and pelvic venous conditions are also discussed. A table is provided for reference.

OBJECTIVE. The purpose of this review is to outline the management guidelines for the care of patients with cystic pancreatic lesions. CONCLUSION. The guidelines are as follows: Annual imaging surveillance is generally sufficient for benign serous cystadenomas smaller than 4 cm and for asymptomatic lesions. Asymptomatic thin-walled unilocular cystic lesions smaller than 3 cm or side-branch intraductal papillary mucinous neoplasms should be followed up with CT or MRI at 6 and 12 months interval after detection. Cystic lesions with more complex features or with growth rates greater than 1 cm/year should be followed more closely or recommended for resection if the patient's condition allows surgery. Symptomatic cystic lesions, neoplasms with high malignant potential, and lesions larger than 3 cm should be referred for surgical evaluation. Endoscopic ultrasound with fine-needle aspiration (FNA) biopsy can be used preoperatively to assess the risk of malignancy.

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.

Neuroendocrine tumors of the pancreas are rare in children. They usually occur in the setting of genetic syndromes such as multiple endocrine neoplasia type 1, von Hippel-Lindau disease, and neurofibromatosis 1. These tumors have also been reported in the tuberous sclerosis complex (TSC), but the incidence is low in comparison with other syndromes. Only 9 cases have been described to date, and it is not yet well understood if any connection exists between TSC and pancreatic endocrine tumors. TSC is characterized by mutations in TSC1 and TSC2 genes, which activate the AKT-mTOR oncogenic cascade. Recent molecular studies in pancreatic endocrine tumors showed activation of the same pathway, which points toward a common molecular pathway between these two entities. We present a case of well-differentiated neuroendocrine carcinoma of the pancreas in a child with TSC and discuss the genetic aspects of this disease.

Variability in how an individual radiologist perceives the relevance and importance of a given pancreatic cyst and how that perception is translated into diagnostic recommendations is of concern to radiologists, gastroenterologists, and surgeons who manage these patients.

We present the imaging findings in a case of penetrating injury to an intercostal artery. The presence of the “sentinel clot sign” within the hemothorax and the extravasation of contrast material were the clues to the site of active bleeding. Active extravasation of contrast agent identified in CT scans may represent a life-threatening hemorrhage that usually requires emergency treatment.

Endovascular repair is increasingly considered a less-invasive alternative to open repair of abdominal aortic aneurysm. However, there are still many potential complications of endovascular repair, including endoleaks, graft migration, thrombosis, and fistula formation. Endoleak is the most common complication for which these patients undergo long-term imaging surveillance. Most centers acquire computed tomographic (CT) data before contrast administration and during an arterial and delayed phase of aortic enhancement after the administration of intravenous contrast material to optimize detection of endoleaks. Although this technique works well, the downside is significant patient radiation exposure. Although the carcinogenic risk of ionizing radiation because of CT exposure is low, it has been linked to an increase in the lifelong risk of developing fatal cancers. Furthermore, this risk is cumulative and increases with multiple radiation exposure, as is true in surveillance after endovascular repair. As a result, considerable research is being performed to optimize CT protocols in an effort to decrease radiation dose. One such approach is to image these patients with recently introduced dual source dual-energy CT system. Using this technique, virtual noncontrast data may be generated from a postcontrast acquisition which may obviate the routine acquisition of noncontrast acquisition, thus decreasing radiation dose. In this article, we discuss the role of dual energy CT imaging in evaluation of patients after endovascular repair of abdominal aortic aneurysm.