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Mesenteric ischemia is a complex and devastating disease which still remains a diagnostic challenge to the clinicians due to non-specific clinical and laboratory findings. Several imaging features have been described with multidetector computed tomography which allows the diagnosis of mesenteric ischemia with high sensitivity and specificity. However, there are imaging features which overlap with other pathologies including benign inflammation and infection. Knowledge of imaging findings in mesenteric ischemia and its potential mimics is important in early and definitive diagnosis. [ABSTRACT FROM AUTHOR]

Aims: This article describes the genesis, contents and outcomes of a bespoke Charge Nurse Development Programme which was designed to enhance the propensity of nurses to manage in an acute hospital setting.Background: The charge nurse role is pivotal to the provision of high-quality care and effective ward management. However, many nurses are promoted to these roles of substantial responsibility commonly with no formal management preparation, an inherent under-confidence and in some cases a tangible reluctance to manage.Evaluation: Evaluations from 95 charge nurses were obtained using an anonymous questionnaire.Key issues: Qualitative analysis demonstrated the programme satisfied its original aims by having role models and experts teaching relevant subjects to a group who have consequently established their own peer network.Conclusions: The pragmatic consequences of the programme were that charge nurses have perceived themselves to become empowered and more focussed on solutions.Implications for nursing management: Creating a supportive but challenging programme has resulted in charge nurses behaving more reflexively by combining reflection with action. This has helped them enhance their confidence, autonomy and responsiveness to organizational, personal and professional objectives. Further work needs to be undertaken to correlate the charge nurses' perceived outcomes against audited standards of their ward performances. [ABSTRACT FROM AUTHOR]

Objective: Topical tissue sealants and hemostatic agents, seen on postoperative imaging in a variety of intraabdominal and pelvic locations, have the potential to be mistaken for abdominal abnormalities, especially if the radiologist is not aware of the patient's surgical history. The normal appearance of these agents may mimic abscesses, tumors, enlarged lymph nodes, or retained foreign bodies. Therefore, it is important to be familiar with their typical imaging appearances and to review the surgical records when needed to avoid misdiagnoses. The purpose of this article is to increase the radiologist's familiarity with various types of topical tissue sealants and hemostatic agents used during surgical and percutaneous procedures in the abdomen and pelvis along with their radiologic appearances., Conclusion: Various types of hemostatic agents are now commonly used during surgery and percutaneous procedures in the abdomen and pelvis, and it is important to recognize the various appearances of these agents. Although there are suggestive features outlined in this article, the most important factor for the radiologist is to be aware of the patient's history and the possibility that a hemostatic agent may be present. On postoperative imaging, hemostatic agents may mimic abscesses, tumors, enlarged lymph nodes, or retained foreign bodies, and accurate diagnosis can save a patient unnecessary treatment. It is therefore crucial to incorporate knowledge of the patient's surgical history with recognition of the typical imaging appearances of hemostatic agents and other pseudolesions to avoid misdiagnoses.

Objective: Dual-energy CT (DECT) is being increasingly used for abdominal imaging because it provides incremental benefit of material characterization without significant increase in radiation dose. This article provides an overview of current DECT techniques and use of DECT in urinary tract imaging for assessment of renal masses and urinary calculi characterization and in CT urography., Conclusion: Incorporation of DECT into clinical practice and use of its material characterization capabilities in urinary tract imaging enable characterization of urinary calculi and incidental renal lesions and can reduce radiation dose by allowing generation of virtual unenhanced images.

Dual-energy CT is being increasingly used for abdominal imaging due to its incremental benefit of material characterization without significant increase in radiation dose. Knowledge of the different dual-energy CT acquisition techniques and image processing algorithms is essential to optimize imaging protocols and understand potential limitations while using dual-energy CT renal imaging such as urinary calculi characterization, assessment of renal masses and in CT urography. This review article provides an overview of the current dual-energy CT techniques and use of dual-energy CT in renal imaging.

Small bowel obstruction (SBO) accounts for a considerable proportion of emergency room visits, inpatient admissions, and surgical interventions in the United States. Multi-detector computed tomography (MDCT) plays a key role in imaging patients presenting with acute symptoms suggestive of SBO, which helps in establishing the diagnosis, elucidating the cause of obstruction, and detecting complications, such as ischemia or frank bowel necrosis and perforation. Recently, management of patients with SBO has shifted toward a more conservative approach with supportive care and nasogastric tube decompression, as the obstruction in many cases can resolve spontaneously without the need for operative intervention. However, management decisions in SBO remain notoriously difficult, relying on a combination of clinical, laboratory, and imaging factors to help stratify patients into conservative or surgical treatment. Imaging is often an important factor assisting in the decision-making process since traditional clinical signs of vascular compromise, such as acidosis, fever, leukocytosis, and tachycardia are often unreliable in predicting the need for operative intervention. Thus, it is critically important for radiologists to identify imaging features that suggest or indicated high likelihood of bowel vascular compromise in order to help optimize management prior to the development of bowel ischemia and eventually necrosis. By excluding signs of potentially ischemic or necrotic bowel on MDCT, patients may be spared unnecessary surgery, thus decreasing postsurgical complications and averting potential increase for the risk of future SBO and repeated surgery. Conversely, if imaging features indicate potential vascular compromise of the bowel wall that may lead to bowel ischemia, urgent surgical intervention may prevent progression to bowel necrosis and subsequent perforation.

Purpose: The aim of this study was to analyze sources of variation influencing the unread volume on an electronic abdominopelvic CT work list and to compare those results with blinded radiologist perception., Methods: The requirement for institutional review board approval was waived for this HIPAA-compliant quality improvement effort. Data pertaining to an electronic abdominopelvic CT work list were analyzed retrospectively from July 1, 2013, to June 30, 2014, and modeled with respect to the unread case total at 6 pm (Monday through Friday, excluding holidays). Eighteen system-level factors outside individual control (eg, number of workers, workload) and 7 human-level factors within individual control (eg, individual productivity) were studied. Attending radiologist perception was assessed with a blinded anonymous survey (n = 12 of 15 surveys completed)., Results: The mean daily unread total was 24 (range, 3-72). The upper control limit (48 CT studies [3 SDs above the mean]) was exceeded 10 times. Multivariate analysis revealed that the rate of unread CT studies was affected principally by system-level factors, including the number of experienced trainees on service (postgraduate year 5 residents [odds ratio, 0.83; 95% confidence interval, 0.74-0.92; P = .0008] and fellows [odds ratio, 0.84; 95% confidence interval, 0.74-0.95; P = .005]) and the daily workload (P = .02 to P < .0001). Individual faculty productivity had a weak effect (Spearman ρ = 0.13, P = .03; adequacy: 3% of variance explained). The majority (67%) of radiologists (8 of 12) completing the survey believed that variation in faculty effort was the most important influence on the daily unread total., Conclusions: System-level factors best predict the variation in unread CT examinations, but blinded faculty radiologists believe that it relates most strongly to variable individual effort., (Copyright © 2015 American College of Radiology. Published by Elsevier Inc. All rights reserved.)

Objective: The purpose of this study was to assess the effect of model-based iterative reconstruction (MBIR) on CT number measurements within small (10-29 mm) low-attenuation renal masses., Materials and Methods: One hundred 10- to 29-mm exophytic or endophytic low-attenuation renal lesions imaged with CT (unenhanced and nephrographic [100 seconds] phases, 120 kVp, variable mA, 2.5-mm slice thickness) were identified in 100 patients. The raw CT source data were prospectively reconstructed twice: once using Veo MBIR and once using a blend of 30% adaptive statistical iterative reconstruction (ASiR) and filtered back projection (FBP). Lesions were chosen to form four equal-sized (n = 25) groups stratified by lesion size (10-19 or 20-29 mm) and growth pattern (endophytic or exophytic). Attenuation (in HU) was measured using identical ROIs and compared with two-tailed t tests. The effects of patient diameter and lesion anatomy on attenuation discrepancies of 5 HU or more were assessed using binary logistic regression., Results: Mean MBIR attenuation was not significantly different than mean 30% ASiR/FBP attenuation in the overall study population (unenhanced phase, 17 ± 13 vs 17 ± 13 HU, p = 0.74; nephrographic phase, 31 ± 27 vs 30 ± 26 HU, p = 0.89) or in any subgroup (p = 0.63-0.95). Only lesion size predicted discrepancies of 5 HU or more (p = 0.008; odds ratio, 1.20 [95% CI, 1.05-1.34] per 1 mm decrease) (p = 0.19-0.98 for the other variables). Seven lesions had enhancement of 20 HU or more with only one reconstruction method (MBIR = 4; 30% ASiR = 3)., Conclusion: Veo MBIR has no significant or consistent effect on attenuation measurements within small (10-29 mm) low-attenuation renal masses and is therefore unlikely to change clinically accepted attenuation thresholds for renal mass characterization.

CT enterography (CTE) is a common examination for patients with Crohn's disease. In order to achieve high quality, diagnostic images, proper technique is required. The purpose of this treatise is to review the processes and techniques that can optimize CTE for patients with suspected or known Crohn's disease. We will review the following: (1) how to start a CT enterography program; (2) workflow issues, including patient and ordering physician education and preparation; (3) oral contrast media options and administration regimens; (4) intravenous contrast media injection for uniphasic and multiphasic studies; (5) CTE radiation dose reduction strategies and the use of iterative reconstruction in lower dose examinations; (6) image reconstruction and interpretation; (7) imaging Crohn's patients in the acute or emergency department setting; (8) limitations of CTE as well as alternatives such as MRE or barium fluoroscopic examinations; and (9) dictation templates and a common nomenclature for reporting findings of CTE in Crohn's disease. Many of the issues discussed are summarized in the Abdominal Radiology Society Consensus MDCT Enterography Acquisition Protocol for Crohn's Disease.

Objective: The purpose of this study was to evaluate stone detection, assessment of secondary signs of stone disease, and diagnostic confidence utilizing submillisievert CT with model-based iterative reconstruction (MBIR) in a North American population with diverse body habitus., Materials and Methods: Fifty-two adults underwent stone CT using a split-dose protocol; weight-based projected volume CT dose index (CTDIvol) and dose-length product (DLP) were divided into two separate acquisitions at 80% and 20% dose levels. Images were reconstructed with MBIR. Five blinded readers counted stones in three size categories and rated "overall diagnostic confidence" and "detectability of secondary signs of stone disease" on a 0-4 scale at both dose levels. Effective dose (ED) in mSv was calculated as DLP multiplied by conversion coefficient, k, equal to 0.017., Results: Mean ED (80%, 3.90±1.44 mSv; vs 20%, 0.97±0.34 mSv [p<0.001]) and number of stones detected (80%, 193.6±25.0; vs 20%, 154.4±15.4 [p=0.03]) were higher in scans at 80% dose level. Intrareader correlation between scans at 80% and 20% dose levels was excellent (0.83-0.97). With 80% scans as reference standard, mean sensitivity and specificity at 20% varied with stone size (<3 mm, 74% and 77%; ≥3 mm, 92% and 82%). The 20% scans scored lower than 80% scans in diagnostic confidence (2.46±0.50; vs 3.21±0.36 [p<0.005]) and detectability of secondary signs (2.41±0.39; vs 3.19±0.29 [p<0.005])., Conclusion: Aggressively dose-reduced (~1 mSv) MBIR scans detected most urinary tract stones of 3 mm or larger but underperformed the low-dose reference standard (3-4 mSv) scans in small (<3 mm) stone detection and diagnostic confidence.

Objective: The purpose of this article is to evaluate single-source dual-energy CT (DECT) for distinguishing benign and indeterminate adrenal nodules, with attention to the effects of phase of IV contrast enhancement., Materials and Methods: A retrospective review revealed 273 contrast-enhanced abdominal DECT examinations from November 2009 through March 2012. Fifty adrenal nodules 0.8 cm or larger were identified in 41 patients (22 women and 19 men; average age, 66 years; age range, 36-88 years). CT postprocessing and measurements were independently performed by two radiologists (readers 1 and 2) for each nodule, as follows: attenuation (in Hounsfield units) on true unenhanced images; contrast-enhanced attenuation (in Hounsfield units) on monochromatic spectral images at 40, 75, and 140 keV; and contrast-enhanced material density (in milligrams per milliliter) on virtual unenhanced images. Nodules were classified as benign (< 10 HU) and indeterminate (≥ 10 HU) according to true unenhanced images., Results: Interreader agreement regarding benign and indeterminate nodules was high (κ = 0.92; 95% CI, 0.8-1.0). At 140 keV, the attenuation of benign nodules was significantly lower (reader 1, 7.0 ± 12.5 HU; reader 2, 7.8 ± 9.2 HU) than that of indeterminate nodules (reader 1, 15.7 ± 20.5 HU [p = 0.004]; reader 2, 17.5 ± 13.4 HU [p < 0.0001]). On virtual unenhanced images, benign nodules had significantly lower material density (reader 1, 992.4 ± 9.9 mg/mL; reader 2, 992.7 ± 9.6 mg/mL) than did indeterminate nodules (reader 1, 1001.1 ± 20.5 mg/mL [p = 0.038]; reader 2, 1007.6 ± 13.4 mg/mL [p < 0.0001])., Conclusion: DECT tools can mathematically subtract iodine or minimize its effects in high-energy reconstructions, approximating unenhanced imaging and potentially reducing the need for additional studies to triage adrenal nodules detected on contrast-enhanced DECT examinations.

Myelolipoma is an uncommon benign tumor that classically arises in the adrenal glands. Most cases are asymptomatic, with incidental detection of this tumor on cross-sectional imaging performed for other causes. Extra-adrenal occurrence of myelolipoma has been infrequently reported, with scarce radiology literature on the topic. We present radiologic and pathologic correlation in two cases of image-guided biopsy proven extra-adrenal myelolipoma in the presacral and paraaortic location, with review of literature.

Objective: The objective of our study was to evaluate image quality and overall adequacy of low-dose CT angiography (CTA) with model-based iterative reconstruction (MBIR) in patients who had undergone endovascular aneurysm repair (EVAR) of a thoracic or abdominal aortic aneurysm., Materials and Methods: Thirty patients, all of whom had undergone standard-dose CTA performed previously with adaptive statistical iterative reconstruction (ASIR), underwent low-dose CTA for surveillance after EVAR. Two radiologists randomly evaluated both studies, and quality parameters were assessed. The maximal aneurysm diameter was measured, and the images were evaluated to see whether an endoleak was present. The image noise and contrast-to-noise ratio (CNR) were measured. The volume CT dose index and dose-length product were recorded., Results: The mean image score for low-dose CTA was acceptable to very good in all categories of assessment. There was no significant difference between low-dose CTA and standard-dose CTA in the evaluation of the stent lumen. Subjective assessments of stent configuration, aneurysm outline, aortic branch vessel outline, overall adequacy of vascular imaging, and overall adequacy of solid organ imaging were superior on standard-dose CTA. Interobserver agreement for endoleak detection was higher for low-dose CTA. There was no significant difference in the mean aneurysm diameter between the two readers on low-dose CTA and standard-dose CTA. The effective radiation dose for low-dose CTA was lower than standard-dose CTA during both the arterial (mean, 4.4 vs 16.2 mSv, respectively) and the delayed (2.4 vs 6.7 mSv) phase acquisitions. The measured image noise was lower (14.7 vs 19.3 HU) and CNR was higher (25.6 vs 17.1) on the low-dose CTA studies than on the standard-dose CTA studies., Conclusion: Low-dose CTA with MBIR enables up to 73% dose reduction as compared with CTA performed with ASIR while maintaining diagnostic adequacy for CTA surveillance of patients who have undergone EVAR of a thoracic or abdominal aortic aneurysm.

The development of multidetector CT technology and helical scanning techniques has revolutionized the use of CT for primary diagnostic evaluation of the abdominal vasculature, particularly the arterial system. CT angiography has numerous benefits relative to conventional catheter angiography, and has largely replaced catheter-based techniques in many clinical algorithms. This pictorial review and update will cover important technical principles related to modern CT angiography (including contrast delivery and dose considerations), discuss relevant anatomy and variants, and illustrate numerous arterial conditions related to the abdominal aorta and branch vessels.

Objective: The purpose of this article is to assess the effects of various CT, patient, and renal cyst characteristics on the occurrence of pseudoenhancement in in vivo renal mass CT examinations using subtraction MRI as the reference standard., Materials and Methods: Adult patients imaged with 120-kVp standard kernel biphasic renal mass protocol CT and dynamic contrast-enhanced MRI of the abdomen from January 1, 2005, through May 4, 2012, were identified. Those with nonenhancing Bosniak categories I and II cysts on MRI were selected (n = 33 patients; 110 cysts). By treating measured cyst enhancement (nephrographic CT attenuation minus unenhanced CT attenuation) as either a continuous or categoric outcome variable, a variety of CT, patient-level, and renal cyst characteristics were assessed using mixed effect multivariate models., Results: On univariate assessment, cysts that exhibited pseudoenhancement (> 10 HU) were significantly more endophytic (p = 0.02), significantly smaller (p = 0.0004), and adjacent to significantly higher attenuation renal parenchyma in the nephrographic phase (p = 0.02). On multivariate assessment, cyst diameter (p < 0.0001) and background nephrographic phase parenchymal attenuation (p = 0.003) were the strongest in vivo predictors of pseudoenhancement. The odds of pseudoenhancement occurring increased by 2.14 (95% CI, 1.41-3.23) for every 5-mm decrease in renal cyst diameter and increased by 2.45 (95% CI, 1.41-4.26) for every 25-HU increase in enhanced renal parenchymal attenuation. Endophytic growth was not significant in the multivariate analyses (p = 0.07)., Conclusion: Renal cyst size and enhanced renal parenchymal attenuation are better in vivo predictors of pseudoenhancement than is endophytic growth pattern.

Recent advances in computed tomographic (CT) scanning technique such as automated tube current modulation (ATCM), optimized x-ray tube voltage, and better use of iterative image reconstruction have allowed maintenance of good CT image quality with reduced radiation dose. ATCM varies the tube current during scanning to account for differences in patient attenuation, ensuring a more homogeneous image quality, although selection of the appropriate image quality parameter is essential for achieving optimal dose reduction. Reducing the x-ray tube voltage is best suited for evaluating iodinated structures, since the effective energy of the x-ray beam will be closer to the k-edge of iodine, resulting in a higher attenuation for the iodine. The optimal kilovoltage for a CT study should be chosen on the basis of imaging task and patient habitus. The aim of iterative image reconstruction is to identify factors that contribute to noise on CT images with use of statistical models of noise (statistical iterative reconstruction) and selective removal of noise to improve image quality. The degree of noise suppression achieved with statistical iterative reconstruction can be customized to minimize the effect of altered image quality on CT images. Unlike with statistical iterative reconstruction, model-based iterative reconstruction algorithms model both the statistical noise and the physical acquisition process, allowing CT to be performed with further reduction in radiation dose without an increase in image noise or loss of spatial resolution. Understanding these recently developed scanning techniques is essential for optimization of imaging protocols designed to achieve the desired image quality with a reduced dose., (© RSNA, 2014.)

Sonohysterography (SHG), which provides enhanced endometrial visualization during standard transvaginal ultrasonography, is a relatively safe procedure for the evaluation of endometrial pathology. It can be used to evaluate patients with abnormal vaginal bleeding or infertility. This modality offers real time imaging of the endometrium without exposure to ionizing radiation. SHG is typically used in patients for whom standard transvaginal ultrasonography does not show the endometrium well, show a potential abnormality for which further imaging is required, or in patients without endometrial pathology defined on routine transvaginal imaging but in whom there is a strong clinical suspicion of an abnormality. This article will discuss the utility of the sonohysterogram in evaluation of various endometrial pathologies. Imaging examples of these pathological entities will be illustrated as well.

Ovarian cystic masses include a spectrum of benign, borderline and high grade malignant neoplasms. Imaging plays a crucial role in characterization and pretreatment planning of incidentally detected or suspected adnexal masses, as diagnosis of ovarian malignancy at an early stage is correlated with a better prognosis. Knowledge of differential diagnosis, imaging features, management trends and an algorithmic approach of such lesions is important for optimal clinical management. This article illustrates a multi-modality approach in the diagnosis of a spectrum of ovarian cystic masses and also proposes an algorithmic approach for the diagnosis of these lesions.

Accurate interpretation of posttherapeutic images obtained in radiation oncology patients requires familiarity with modern radiation therapy techniques and their expected effects on normal tissues. Three-dimensional conformal external-beam radiation therapy techniques (eg, intensity-modulated radiation therapy, stereotactic body radiation therapy), although they are designed to reduce the amount of normal tissue exposed to high-dose radiation, inevitably increase the amount of normal tissue that is exposed to low-dose radiation, with the potential for resultant changes that may evolve over time. Currently available internal radiation therapy techniques (eg, arterial radioembolization for hepatic malignancies, brachytherapy for prostate cancer and gynecologic cancers) also carry risks of possible injury to adjacent nontargeted tissues. The sensitivity of tissues to radiation exposure varies according to the tissue type but is generally proportional to the rate of cellular division, with rapidly regenerating tissues such as intestinal mucosa being the most radiosensitive. The characteristic response to radiation-induced injury likewise varies according to tissue type, with atrophy predominating in epithelial tissue whereas fibrosis predominates in stromal tissue. Moreover, changes in irradiated tissues evolve over time: In the liver, decreased attenuation at computed tomography and increased signal intensity at T2-weighted magnetic resonance imaging reflect hyperemia and edema in the early posttherapeutic period; later, veno-occlusive changes alter the hepatic enhancement pattern; and finally, fibrosis develops in some patients. In the small bowel, wall thickening and mucosal hyperenhancement predominate initially, whereas luminal narrowing is the most prominent feature of chronic enteropathy. Correlation of posttherapeutic images with images used for treatment planning may be helpful when interpreting complex cases.

Aim: To investigate the frequency, typical and atypical locations and patterns of melanoma metastases identifiable by computed tomography (CT) in the abdomen and pelvis., Methods: We performed a retrospective review of index CT examinations of the abdomen and pelvis in patients with melanoma and recorded all findings suggestive of metastatic disease., Results: Metastases were present on 36% (181/508) of the index examinations and most commonly involved the liver (47%) and pelvic lymph nodes (27%). Lower extremity primaries had the highest rate of metastasis (52%). Ocular and head and neck melanomas have a predilection to metastasize to the liver (hepatic involvement in 70% and 63%, respectively, of patients with metastatic disease) and metastases from lower extremity primaries most commonly involve pelvic lymph nodes (54% of patients with metastatic disease). Metastases to atypical locations were present in 14% of patients and most commonly occurred in the subcutaneous tissue and spleen. Primary tumors of the lower extremity, back and head and neck were most commonly associated with atypical metastases. Pelvic metastases are more common with lower extremity primaries (accounting for 70% of cases with pelvic metastases) but 5% of patients with supraumbilical primaries also had pelvic metastases., Conclusion: The distribution of metastatic melanoma in the abdomen and pelvis that we have defined should help guide the interpretation of CT exams in these patients.

With the ability to provide structural- and material-specific information with single phase of image acquisition, dual-energy CT has several useful applications in urinary tract imaging such as evaluation of renal mass, CT urography, and characterization of urinary calculi. Although the underlying principle of dual-energy scanning is similar, there are several important differences in the currently available dual-energy scanners and the image processing algorithms used for these scanners. Knowledge of the principle of dual-energy data acquisition and image processing is essential to understand the advantages and limitations of dual-energy CT in urinary tract imaging.

Crohn's disease represents a heterogeneous group of patients who have different clinical phenotypes. Computed tomography enterography (CTE) has been validated and optimized over the recent years since its introduction in the past decade and now has a clear established role as one of the primary diagnostic tools in the evaluation of patients with Crohn's disease. This article describes the current clinical concepts in Crohn's disease activity assessment and the use of imaging as well as the typical imaging findings in different subtypes of Crohn's disease using CTE., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Scrotal symptoms including palpable mass or pain often bring men to medical attention. Ultrasound serves as an extension of the physical examination in these patients and, in most cases, allows definitive diagnosis. Although the diagnosis of malignancy is of greatest concern both to the patient and clinician, a number of benign scrotal pathologies exist and most have characteristic imaging features. Knowledge of these imaging findings can help the radiologist to confidently identify common benign scrotal conditions. Location and imaging characteristics of uncommon lesions help to establish a rational differential diagnosis and appropriate recommendations for patient management.

Objective: The objective of our study was to evaluate the image quality and diagnostic adequacy of the following two CT enterography protocols in patients weighing less than 160 lb (72 kg): 80-kVp imaging with the adaptive statistical iterative reconstruction (ASIR) in comparison with 120-kVp imaging with the filtered back projection reconstruction., Materials and Methods: We retrospectively reviewed 133 CT enterography examinations of 127 patients weighing less than 160 lb, 64 80-kVp examinations, and 69 120-kVp examinations. Image quality for evaluation of the bowel wall, mesenteric vessels, and hepatic parenchyma and the overall image quality were graded on a scale of 1-5 (1 = poor, 2 = acceptable, 3 = good, 4 = very good, 5 = excellent). Diagnostic accuracy for the detection of inflammatory bowel disease was evaluated. The volume CT dose index (CTDI(vol)) was recorded and effective dose was calculated from scanner-generated dose-length product., Results: There was a statistically significant decrease in the mean image quality scores for 80-kVp examinations compared with 120-kVp examinations for evaluation of the bowel wall (3.19 vs 3.70, respectively) and liver (3.12 vs 3.81) and for overall image quality (3.23 vs 3.68), but there was no significant decrease in score for evaluation of the mesenteric vessels (3.63 vs 3.67). None of the 80-kVp examinations was graded as poor, and all were considered to be of acceptable quality. Both techniques had comparable diagnostic accuracy for the detection of inflammatory bowel disease. Interobserver agreement was fair to moderate for qualitative image grading and was substantial for the detection of features of inflammatory bowel disease. The mean CTDI(vol) and effective dose for the 80-kVp examinations were 6.15 mGy and 4.60 mSv, respectively, and for the 120-kVp examinations, 20.79 mGy and 15.81 mSv., Conclusion: In patients weighing less than 160 lb, CT enterography examinations at 80 kVp with 30% ASIR produce diagnostically acceptable image quality with an average CTDI(vol) of 6.15 mGy and an average effective dose of 4.60 mSv.

Background: It has become commonplace to categorize small intestinal Crohn's disease (CD) as "active" vs. "inactive" or "inflammatory" vs. "fibrotic" based on computed tomography enterography (CTE) findings. Data on histologic correlates of CTE findings are lacking. We aimed to compare CTE findings with histology from surgically resected specimens. We tested the hypothesis that CTE findings can distinguish tissue inflammation from fibrosis., Methods: Patients who underwent CTE within 3 months before intestinal resection for CD were retrospectively studied. Radiologists blinded to history and histology scored findings on CTE. Pathologists blinded to history and imaging scored resected histology. We compared histology with CTE findings and radiologists assessment of whether the stricture was likely "active" or "inactive.", Results: In all, 22 patients met inclusion criteria. Inflammatory CTE findings correlated with histologic inflammation (rho = 0.52). Strictures believed to be "active" on CTE were more inflamed at histology (P = 0.0002). Strictures lacking inflammatory findings on CTE or considered "inactive" were not associated with greater histologic fibrosis or significant histologic inflammation. Upstream dilation was associated with greater tissue fibrosis in univariate (P = 0.014) but not in multivariate analysis (P = 0.53). Overall, histologic fibrosis correlated best with histologic inflammation (rho = 0.52). Strictures on CTE with the most active disease activity also had the most fibrosis on histology., Conclusions: CTE findings of mesenteric hypervascularity, mucosal hyperenhancement, and mesenteric fat stranding predict tissue inflammation. However, small bowel stricture without CTE findings of inflammation does not predict the presence of tissue fibrosis. Therefore, caution should be used when using CTE criteria to predict the presence of scar tissue., (Copyright © 2011 Crohn's & Colitis Foundation of America, Inc.)

Several promising clinical applications for dual-energy computed tomography (CT) in genitourinary imaging have been reported. Dual-energy CT not only provides excellent morphologic detail but also can supply material-specific and quantitative information that may be particularly useful in genitourinary imaging. Dual-energy CT has unique capabilities for characterizing renal lesions by quantifying iodine content and helping identify the mineral contents of renal stones, information that is important for patient care. Virtual unenhanced images reconstructed from dual-energy CT datasets can be useful for detecting calculi within the iodine-filled urinary collecting system, potentially reducing the need for an unenhanced scanning phase at CT urography. Although the underlying principles of dual-energy CT are the same regardless of scanner type, single-source dual-energy scanners with fast kilovoltage switching differ from dual-source dual-energy scanners both in image data acquisition and in processing methods; an understanding of these differences may help optimize dual-energy CT genitourinary protocols. Dual-energy CT performed with a dual-source scanner or with a single-source scanner with fast kilovoltage switching also has some important limitations. Further advances in scanning protocols and refinement of processing techniques to reduce image noise may lead to more widespread use of dual-energy CT., (© RSNA, 2012.)

Objective: To assess endoleak detection and conspicuity using low-kiloelectron volt (keV) monochromatic reconstructions of single-source (fast-switch kilovolt [peak]) dual-energy data sets., Methods: With approval of the institutional review board, multiphasic dual-energy computed tomographic (CT) scans for aortic endograft surveillance were retrospectively reviewed for 39 patients. Two abdominal radiologists each performed 2 separate reading sessions, at 55-keV and standard 75-keV reconstruction, respectively. The readers tabulated endoleak presence, conspicuity on 1-to-5 scale, and type overall and in arterial and venous phases. Originally, dictated reports in medical records were used as criterion standard., Results: Original dictations identified 19 endoleaks (9 abdominal and 10 thoracic), 13 of which were type II. The blinded readers (R1 and R2) exhibited good to very good intraobserver and interobserver agreement. Endoleak detection was higher at 55 keV than at 75 keV (sensitivity, 100% (95% confidence interval [CI], 82.4%-100.0%) and 84.2% (95% CI, 60.4-96.6%) at 55 keV vs 79% (95% CI, 54.4-94.0%) and 68.4% (95% CI, 43.5%-87.4%) at 75 keV in venous phase). Further, endoleak conspicuity ratings (where original dictation showed positive leak) were higher at 55 keV than at 75 keV, which was a significant difference for R2 in the overall ratings (P = 0.03) and for both readers in the venous phase ratings (R1, P = 0.01; R2, P = 0.004). There was no difference in endoleak type characterization between the kiloelectron volt levels., Conclusion: Sensitivity for endoleak detection and overall endoleak conspicuity ratings were both higher at 55 keV than 75 keV, favoring the inclusion of a lower-energy monochromatic reconstruction for endoleak surveillance protocols with dual-energy computed tomography.

Objective: The purpose of this article is to evaluate the accuracy of dual-energy CT in distinguishing enhancing from nonenhancing or equivocally enhancing renal lesions., Materials and Methods: We retrospectively reviewed fast kilovoltage-switching dual-energy renal mass CT performed in 39 patients. On the contrast-enhanced dual-energy CT scans, renal lesions were graded subjectively for enhancement using iodine density images and iodine overlay images. Lesion iodine density was measured to identify an optimal threshold for detection of enhancement. Lesion attenuation measurements on unenhanced and contrast-enhanced scans were performed to identify enhancing (increase of > 20 HU) lesions, which were used as the reference standard. Sensitivity, specificity, and accuracy for detection of enhancement were calculated for the different dual-energy CT techniques., Results: Eighty-three renal lesions were evaluated. On the basis of attenuation measurements, there were 20 enhancing and 63 nonenhancing lesions. The sensitivity, specificity, and accuracy for the detection of enhancement according to the lesion appearance were 70%, 98.4%, and 91.6%, respectively, on iodine density images and were 85%, 90.5%, and 89.2%, respectively, on iodine overlay images generated from contrast-enhanced dual-energy CT scans. Of the various thresholds of measured lesion iodine density (1-3 mg/cm(3)), a threshold of 2 mg/cm(3) showed the highest accuracy for the detection of enhancement, with sensitivity, specificity, and accuracy of 90%, 93.7%, and 92.8%, respectively., Conclusion: Fast kilovoltage-switching dual-energy CT is highly specific in excluding enhancement and moderately to highly sensitive in detecting enhancement of renal lesions. Of the available dual-energy CT techniques, iodine density measurement using a threshold of 2 mg/cm(3) is most accurate in distinguishing enhancing from nonenhancing renal lesions.

Objective: To assess endoleak detection and patients' radiation exposure using fast-switch peak kilovoltage (kVp) dual-energy computed tomography (DECT) with virtual noncontrast (VNC) imaging., Methods: Institutional review board approved retrospective review of triphasic CTs for endograft follow-up: single-energy true noncontrast (TNC) and dual-energy arterial- and venous-phase postcontrast scans on GE HD-750 64-detector scanners. Iodine-subtracted VNC images generated from dual-energy data. Two radiologists (VNC readers) independently performed 2 reading sessions without TNC images: (1) arterial and VNC and (2) venous and VNC. Interrater agreement, leak detection sensitivity, and dose estimates were calculated., Results: Original dictations described 24 endoleaks in 78 scans. Virtual noncontrast reader agreement was high (κ = 0.78-0.79). Virtual noncontrast reader ranges for sensitivity and negative predictive value for leak detection were 87.5% to 95.8% and 94.0% to 98.0% in venous phase. Dose reduction estimate was 40% by eliminating one phase and 64% by eliminating 2 phases of imaging., Conclusion: Virtual noncontrast images from fast-switch peak kilovoltage DECT data can substitute for TNC imaging in the postendograft aorta, conferring substantial dose reduction. Eliminating 1 of 2 postcontrast phases further reduces dose, with greater negative predictive value for leak detection in the venous versus the arterial phase. Thus, the use of a monophasic venous-phase DECT with VNC images is suggested for long-term endograft surveillance in stable patients.

Purpose: To retrospectively correlate sonographic color Doppler twinkling artifact within the kidneys with unenhanced computed tomography (CT) in the detection of nephrolithiasis., Materials and Methods: Institutional review board approval was obtained for this retrospective HIPAA-complaint investigation, and the informed consent requirement was waived. Sonographic imaging reports describing the presence of renal twinkling artifact between January 2008 and September 2009 were identified. Subjects who did not undergo unenhanced abdominal CT within 2 weeks after sonography were excluded. Ultrasound examinations were reviewed by three radiologists working together, and presence, number, location, and size of renal twinkling artifacts were documented by consensus opinion. Sonographic findings were correlated with unenhanced CT (5-mm section width, no overlap) for nephrolithiasis and other causes of twinkling artifact. The number, location, and size of renal calculi at CT were documented., Results: The presence of sonographic renal twinkling artifact, in general, had a 78% (95% confidence interval: 0.66, 0.90) positive predictive value for nephrolithiasis anywhere in the kidneys at CT. The true-positive rate of twinkling artifact for confirmed calculi at CT was 49% (73 of 148 twinkling foci), while the false-positive rate was 51% (75 of 148 twinkling foci). The overall sensitivity of twinkling artifact for the detection of specific individual renal calculi observed at CT was 55% (95% confidence interval: 0.47, 0.64)., Conclusion: While renal twinkling artifact is commonly associated with nephrolithiasis, this finding is relatively insensitive in routine clinical practice and has a high false-positive rate when 5-mm unenhanced CT images are used as the reference standard., Supplemental Material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11102128/-/DC1., (RSNA, 2011)

Several noninvasive imaging techniques have been developed and improved over recent years that facilitate detection of both vascular and nonvascular postoperative complications as well as diagnosis of diseases related to the transplanted organ itself. In this article, we present a multi-modality review of the spectrum of pathology related to renal transplantation., (Copyright © 2011. Published by Mosby, Inc.)

Computed tomographic (CT) enterography is an emerging alternative to traditional fluoroscopy for the assessment of disorders of the small bowel. The greatly improved spatial and temporal resolution provided by multidetector CT scanners, combined with good luminal distention provided by negative oral contrast agents and with good bowel wall visualization, have made CT enterography the main imaging modality not only for investigating proved or suspected inflammatory bowel disease but also for detecting occult gastrointestinal tract bleeding, small bowel neoplasms, and mesenteric ischemia. CT enterography is particularly useful for differentiating between active and fibrotic bowel strictures in patients with Crohn disease, thus enabling selection of the most appropriate treatment (medical management or intervention) for an improved outcome. CT enterography allows excellent visualization of the entire thickness of the bowel wall and depicts extraenteric involvement as well, providing more detailed and comprehensive information about the extent and severity of the disease process., (©RSNA, 2010.)

As multidetector CT has come to play a more central role in medical care and as CT image quality has improved, there has been an increase in the frequency of detecting "incidental findings," defined as findings that are unrelated to the clinical indication for the imaging examination performed. These "incidentalomas," as they are also called, often confound physicians and patients with how to manage them. Although it is known that most incidental findings are likely benign and often have little or no clinical significance, the inclination to evaluate them is often driven by physician and patient unwillingness to accept uncertainty, even given the rare possibility of an important diagnosis. The evaluation and surveillance of incidental findings have also been cited as among the causes for the increased utilization of cross-sectional imaging. Indeed, incidental findings may be serious, and hence, when and how to evaluate them are unclear. The workup of incidentalomas has varied widely by physician and region, and some standardization is desirable in light of the current need to limit costs and reduce risk to patients. Subjecting a patient with an incidentaloma to unnecessary testing and treatment can result in a potentially injurious and expensive cascade of tests and procedures. With the participation of other radiologic organizations listed herein, the ACR formed the Incidental Findings Committee to derive a practical and medically appropriate approach to managing incidental findings on CT scans of the abdomen and pelvis. The committee has used a consensus method based on repeated reviews and revisions of this document and a collective review and interpretation of relevant literature. This white paper provides guidance developed by this committee for addressing incidental findings in the kidneys, liver, adrenal glands, and pancreas., (Copyright © 2010 American College of Radiology. Published by Elsevier Inc. All rights reserved.)

Although catheter angiography remains the accepted gold standard for imaging of the renal vascular system, rapid progress in cross-sectional imaging techniques has caused a paradigm shift in many diagnostic algorithms toward noninvasive techniques such as computed tomographic angiography (CTA). CTA's cross-sectional imaging techniques provide an opportunity for comprehensive renal investigation that would be impossible with angiography alone. While other competing noninvasive technologies such as ultrasound and magnetic resonance angiography can be used successfully in renal imaging, the benefits of CTA are substantial, including high spatial and temporal resolution, widespread availability, implantable device compatibility, and easy technical reproducibility. This article describes the technical considerations relevant to CTA of the renal vascular system, postprocessing algorithms for volumetric data, and numerous specific applications., (Copyright 2010 Elsevier Inc. All rights reserved.)

The placenta is often overlooked in the routine evaluation of a normal gestation, receiving attention only when an abnormality is detected. Although uncommon, abnormalities of the placenta are important to recognize owing to the potential for maternal and fetal morbidity and mortality. Pathologic conditions of the placenta include placental causes of hemorrhage, gestational trophoblastic disease, retained products of conception, nontrophoblastic placental tumors, metastases, and cystic lesions. Sonography remains the imaging modality of choice for evaluation of the placenta. Magnetic resonance (MR) imaging can be of added diagnostic value when further characterization is required, particularly in the setting of invasive placental processes such as placenta accreta and gestational trophoblastic disease. Computed tomography (CT) has a limited role in the evaluation of placental disease owing to limited tissue characterization, compared with that of MR imaging, and the radiation risk to the fetus; this risk often outweighs the benefit. The primary role for CT is in the evaluation of trauma and gestational trophoblastic disease, for which it allows characterization of the primary lesion and distant metastases., ((c) RSNA, 2009.)

Pancreas transplantation has become more commonplace over the past several decades. Consequently, the radiological evaluation of patients with such transplants has also become more common. Radiologists must therefore be familiar with the normal imaging appearances of pancreas transplant grafts as well as a wide variety of transplant-related complications. In this article, we review the cross-sectional imaging appearances of normal pancreas transplant grafts as well as present representative examples of complications associated with the procedure.

The introduction of saline infusion sonohysterography has significantly improved sonographic diagnosis of various endometrial pathologies. This procedure entails instillation of warm saline into the uterine cavity transcervically to provide enhanced visualization of the endometrium during transvaginal ultrasound examination. This article reviews the sonohysterography technique and current utility, as well as the spectrum of imaging features of various endometrial pathologies.

Diabetes mellitus is the most common multisystemic endocrine disorder. It can be complicated by several serious gastrointestinal manifestations that can be depicted by a variety of imaging methods. This article reviews the most commonly depicted gastrointestinal and hepatobiliary findings in patients with diabetes mellitus. These findings include motor dysfunction, biliary stasis with cholelithiasis and emphysematous cholecystitis, and fatty infiltration of the liver and pancreas.

Objective: The purpose of this review is to describe the role of imaging and associated findings in the diagnosis of blue rubber bleb nevus syndrome, Proteus syndrome, Klippel-Trénaunay syndrome, and Kasabach-Merritt syndrome., Conclusion: Blue rubber bleb nevus, Proteus, Klippel-Trénaunay, and Kasabach-Merritt syndromes are a diverse group of vascular malformation and hemangiomatosis syndromes. Both cutaneous and visceral vascular lesions are associated with these disorders. Accurate diagnosis of these syndromes is important because they can be associated with serious complications, including life-threatening hemorrhage.

Purpose: To determine whether individual and regional liver sensitivity to radiation could be assessed by measuring liver perfusion during a course of treatment using dynamic contrast-enhanced computed tomography scanning., Methods and Materials: Patients with intrahepatic cancer undergoing conformal radiotherapy underwent dynamic contrast-enhanced computed tomography (to measure perfusion distribution) and an indocyanine extraction study (to measure liver function) before, during, and 1 month after treatment. We hoped to determine whether the residual functioning liver (i.e., those regions showing portal vein perfusion) could be used to predict overall liver function after irradiation., Results: Radiation doses from 45 to 84 Gy resulted in undetectable regional portal vein perfusion 1 month after treatment. The volume of each liver with undetectable portal vein perfusion ranged from 0 to 39% and depended both on the patient's sensitivity and on dose distribution. There was a significant correlation between indocyanine green clearance and the mean of the estimated portal vein perfusion in the functional liver parenchyma (p < 0.001)., Conclusion: This study reveals substantial individual variability in the sensitivity of the liver to irradiation. In addition, these findings suggest that hepatic perfusion imaging may be a marker for liver function and has the potential to be a tool for individualizing therapy.

Multidetector computed tomography is a highly accurate method in evaluating high-grade intestinal obstruction. Closed-loop obstruction is a relatively uncommon subcategory of small-bowel obstruction; however, it is associated with a high risk of vascular impairment and is, therefore, important to diagnose accurately. Closed-loop obstruction is often caused by conditions such as internal hernias, congenital bands, postoperative adhesions, and malrotation. The purpose of this article is to review the imaging features of closed-loop bowel obstruction and various underlying conditions. Special emphasis will be placed on the technique of multidetector computed tomography and its role in diagnosing this entity.