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Abstract Background Gastrointestinal stromal tumours (GIST) usually present with non-specific gastrointestinal symptoms such as abdominal mass, pain, anorexia and bowel obstruction. Methods We report a case of a 42 year old male who presented with a solitary intracranial space occupying lesion which was established as a metastasis from a mesenteric tumour. Results The patient was initially treated as a metastatic sarcoma, but a lack of response to chemotherapy prompted testing for CD117 which returned positive. A diagnosis of mesenteric GIST presenting as solitary brain metastasis was made, and the patient was treated with imatinib. Conclusion We recommend that all sarcomas with either an intraabdominal or unknown origin be routinely tested for CD117 to rule out GIST.

The authors review ultrasound (US) imaging findings of the abdominal aorta and mesenteric arteries, with a focus on screening for abdominal aortic aneurysm (AAA) and posttreatment follow-up. US is the primary imaging modality used to screen for AAA and for surveillance of aneurysms for growth after initial diagnosis. US and contrast-enhanced US may play a greater role in patient follow-up status post-endovascular aneurysm repairs. US is also the initial recommended imaging modality for suspected chronic mesenteric ischemia., Competing Interests: Disclosure L.M. Scoutt is an educational consultant for Philips Healthcare (not directly related to this study). M.L. Robbin: Philips Medical, contract, ongoing. Philips Medical Vascular Advisory Board (single session), 2/2023. Jazz Pharmaceuticals, VOD Advisory Board (single session), 6/2023., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Ultrasound is the first-line imaging modality used in patients with suspected renovascular disease. Common indications include renovascular hypertension and unexplained renal dysfunction. We review the ultrasound imaging findings of various pathologies involving the renal vessels, including the renal arteries (atherosclerotic stenosis, fibromuscular dysplasia, dissection, arteriovenous fistula, and aneurysm) and veins (tumor and bland thrombus as well as vascular compression syndromes). The current role of renal artery stent placement for atherosclerotic stenosis is also discussed., (© 2024 American Institute of Ultrasound in Medicine.)

Objective: To assess the safety and utility of deferring estimated glomerular filtration rate (eGFR) testing before contrast-enhanced CT (CECT) in low-risk emergency department (ED) patients., Methods: A new question was added to CECT order screens, allowing ordering ED providers to defer eGFR testing in patients deemed low risk for contrast-induced acute kidney injury (AKI). Low risk was defined as no known chronic kidney disease (CKD) or risk factors for AKI or CKD. Patients on chronic dialysis were deemed low risk. The project included three phases: baseline, pilot (optional order question), and full implementation (required order question). Outcomes were operational throughput metrics of CECT order to protocol (O to P) and order to begin (O to B) times. As a balancing safety measure, the proportion of patients deemed to be "low risk" and subsequently found to have eGFR value less than 30 mL/min/1.73 m 2 was reported., Results: A total of 16,446 CECT studies were included from four EDs. In the pilot phase, provider engagement rates with the question were low (5%-14%). After full implementation, median O to P time improved from 23.93 min at baseline to 13.02 (P < .0001) and median O to B time improved from 80.34 min to 76.48 (P = .0002). In 0.3% (2 of 646) studies, CECT was completed in patients categorized as low risk by the ED provider with subsequently resulted eGFR <30 mL/min/1.73 m 2 ., Discussion: Upfront clinical risk assessment for AKI and CKD by ED providers can be used to safely defer eGFR testing and improve operational performance for patients requiring CECT., (Copyright © 2023 American College of Radiology. Published by Elsevier Inc. All rights reserved.)

Imaging pitfalls commonly occur in carotid Doppler ultrasound and may lead to false positive diagnosis of stenosis, missed diagnosis of stenosis, and errors in grading stenosis severity. These pitfalls may result from suboptimal technique and/or patient-specific factors including coexisting cardiovascular pathology, contralateral high-grade stenosis/occlusion, tortuous vessels, tandem lesions, long-segment stenosis, nearly occlusive stenosis, and heavily calcified plaque. Awareness of these pitfalls and careful assessment of the extent of plaque on grayscale and color Doppler as well as analysis of the spectral Doppler waveforms can help avoid misinterpretation of the carotid Doppler examination., (© 2023 American Institute of Ultrasound in Medicine.)

Abstract: Chronic venous insufficiency is a common condition caused by valvular incompetence and/or obstruction of the lower extremity venous system. Chronic venous insufficiency presents in a wide range of clinical presentations, ranging from mild pain or edema to the development of varicose veins and nonhealing venous ulcers. Doppler ultrasound is the preferred imaging modality in the assessment of this condition and provides both anatomical and functional information in a noninvasive, cost-effective, and radiation-free manner. Knowledge of the anatomy and nomenclature, pathophysiology, equipment requisites, scanning protocols, relevant findings, and reporting nuances is essential to the creation of an accurate and clinically actionable report. Evaluation of the superficial and deep venous system for degree and extent of reflux is necessary to establish the diagnosis and to institute appropriate treatment., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Purpose: To assess the Liver Imaging Reporting and Data System (LI-RADS) and radiomic features in pretreatment magnetic resonance (MR) imaging for predicting progression-free survival (PFS) in patients with nodular hepatocellular carcinoma (HCC) treated with radiofrequency (RF) ablation., Material and Methods: Sixty-five therapy-naïve patients with 85 nodular HCC tumors <5 cm in size were included in this Health Insurance Portability and Accountability Act-compliant, institutional review board-approved, retrospective study. All patients underwent RF ablation as first-line treatment and demonstrated complete response on the first follow-up imaging. Gadolinium-enhanced MR imaging biomarkers were analyzed for LI-RADS features by 2 board-certified radiologists or by analysis of nodular and perinodular radiomic features from 3-dimensional segmentations. A radiomic signature was calculated with the most informative features of a least absolute shrinkage and selection operator Cox regression model using leave-one-out cross-validation. The association between both LI-RADS features and radiomic signatures with PFS was assessed via the Kaplan-Meier analysis and a weighted log-rank test., Results: The median PFS was 19 months (95% confidence interval, 16.1-19.4) for a follow-up period of 24 months. Multifocality (P = .033); the appearance of capsular continuity, compared with an absent or discontinuous capsule (P = .012); and a higher radiomic signature based on nodular and perinodular features (P = .030) were associated with poorer PFS in early-stage HCC. The observation size, presence of arterial hyperenhancement, nonperipheral washout, and appearance of an enhancing "capsule" were not associated with PFS (P > .05)., Conclusions: Although multifocal HCC clearly indicates a more aggressive phenotype even in early-stage disease, the continuity of an enhancing capsule and a higher radiomic signature may add value as MR imaging biomarkers for poor PFS in HCC treated with RF ablation., (Copyright © 2022 SIR. Published by Elsevier Inc. All rights reserved.)

Understanding the basics and nuances of the functionality of ultrasound (US) equipment and of its various knobs and modes will enable the interventional radiologist to acquire higher quality US images. This, in turn will potentially allow US-guided procedures to be performed safely, and with greater operator confidence, and may also allow certain procedures to be performed with US instead of CT or fluoroscopic guidance. In this article, we review the practical aspects of US image optimization for the interventional radiologist, including equipment and transducer selection, depth, focal zone and gain setting adjustment, as well as special considerations for imaging the obese patient. Color Doppler image optimization and recent developments in ultrasound imaging are briefly discussed., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Non-traumatic adrenal crisis is a rare but critical diagnosis to make in emergency settings due to grave consequences. Various pathologies can present as acute crisis, such as spectrum of endocrine imbalance, ranging from catecholamine excess in pheochromocytomas to acute adrenal insufficiency related to glandular dysfunction. Critical manifestations may be due to structural causes related to adrenal hemorrhage, especially when they are bilateral. Oncological complications such as vascular invasion, tumoral bleed, rupture, and hormonal dysfunction can occur. Due to non-specific clinical presentation, these conditions may come as a surprise on imaging performed for other reasons. Recognition of these imaging findings is critical for appropriate patient management. Although there are few articles discussing non-traumatic emergencies in literature, this review is inclusive of all possible etiologies, thus provides a holistic approach and insight into each situation. Specific imaging approach is needed to tailor the diagnosis. This article will also discuss about the advanced imaging techniques that will complement diagnosis.

Objective: The objective of the study was to evaluate the safety and efficacy of percutaneous cholecystostomy (PC) in treating critically ill patients with emphysematous cholecystitis who were deemed poor surgical candidates., Materials and Methods: The Institutional Review Board exemption was obtained for this retrospective study. Patients with emphysematous cholecystitis who were deemed to be poor operative candidates by the treating surgeon and underwent PC placement between May 2008 and April 2017 at a single institution were identified through a medical records search. Demographics, laboratory values, imaging data, procedural technique, complications, hospitalization course, clinical outcome, and survival data were obtained., Results: Ten consecutive patients were included, with a mean age of 75.0 ± 12.2 years, including six men and four women. The most common comorbidity was diabetes (60%, 6/10) followed by hypertension (40%, 4/10). Intraluminal or intramural gas as well as gallbladder wall thickening were noted in all patients. Procedure technical success rate was 100%. There was a complete resolution of symptoms in 90% (9/10) of patients at a mean of 2.9 ± 1.4 days post-procedure. Thirty-day survival rate was 90% (9/10); one patient died on the 6 th post- procedure day from sepsis. Two more deaths occurred within a year after PC from unrelated causes. About 50% (5/10) of patients underwent elective cholecystectomy at a median interval of 69 days post-procedure. In 40% (4/10) of patients, cholecystostomy was the definitive treatment, with tube removal at a median of 140 days post- procedure., Conclusion: PC appears to be a safe and generally effective alternative management option in patients with emphysematous cholecystitis that is considered very high risk for surgery., Competing Interests: There are no conflicts of interest., (© 2020 Published by Scientific Scholar on behalf of Journal of Clinical Imaging Science.)

Objective: To develop and disseminate an automated item generation (AIG) system for retrieval practice (self-testing) in radiology and to obtain trainee feedback on its educational utility., Materials and Methods: An AIG software program (Radmatic) that is capable of generating large numbers of distinct multiple-choice self-testing items from a given "item-model" was created. Instead of writing multiple individual self-testing items, an educator creates an "item-model" for one of two distinct item styles: true/false knowledge based items and image-based items. The software program then uses the item model to generate self-testing items upon trainee request. This internet-based system was made available to all radiology residents at our institution in conjunction with our didactic conferences. After obtaining institutional review board approval and informed consent, a written survey was conducted to obtain trainee feedback., Results: Two faculty members with no computer programming experience were able to create item-models using a standard template. Twenty five of 54 (46%) radiology residents at our institution participated in the study. Twelve of these 25 (48%) study participants reported using the self-testing items regularly, which correlated well with the anonymous website usage statistics. The residents' overall impression and satisfaction with the self-testing items was quite positive, with a score of 7.89 ± 1.91 (mean ± SD) out of 10. Lack of time and email overload were the main reasons provided by residents for not using self-testing items., Conclusion: AIG enabled self-testing is technically feasible, and is perceived positively by radiology residents as useful to their education., (Copyright © 2018 The Association of University Radiologists. All rights reserved.)

Objectives: Ultrasound simulators are increasingly used for teaching and training purposes, but development has been limited by the need for dedicated and often expensive hardware. The objective of this study was to develop and deploy an accessible and very low-cost personal ultrasound training simulator and obtain trainee feedback., Methods: An ultrasound simulator software program that uses a smartphone as a "mock-probe" and a laptop computer as a "mock ultrasound machine" was created. Spatial positional data is acquired from the smartphone's inbuilt accelerometer and gyroscope and transmitted to the laptop computer for processing and display of simulated ultrasound images in real time by the software program. After obtaining institutional review board approval and informed consent, all first-year radiology residents at our institution were provided access to the simulator program during the "bootcamp" introductory conference series, and a written survey was conducted to obtain feedback., Results: A personal ultrasound training simulator software program (Persimus) that reliably performs motion sensing along 2 axes and displays simulated ultrasound images was developed. Nine of 12 (75%) first-year residents at our institution participated in the written survey. Residents' scored values were 8.44 ± 1.33 and 8.44 ± 1.33 (mean + standard deviation) for perceived utility and overall impression and satisfaction, respectively, of the simulator on the Likert scale (1-10, with 10 being the highest score)., Conclusion: Personal ultrasound simulators are technically feasible. These are well received by first-year radiology residents and perceived as useful to their education., (© 2018 by the American Institute of Ultrasound in Medicine.)

There is renewed interest in ultrasound imaging of the vertebral artery due to the increasing use of stent placement for treating vertebral artery stenosis. Changes in vertebral artery waveforms are helpful in detecting pathologic processes involving the proximal and distal neurovascular circulation. We review the normal anatomy, scanning technique, normal gray scale, and color Doppler ultrasound appearance and differential diagnosis of spectral Doppler waveform changes in the extracranial vertebral artery. We review the ultrasound criteria for diagnosing vertebral artery stenosis, and the imaging appearance of non-atherosclerotic pathology that may affect the vertebral artery, including dissection, pseudoaneurysm, and arteriovenous fistula., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Doppler ultrasound (US) is the primary noninvasive imaging modality for detecting, grading, and monitoring extracranial internal carotid artery (ICA) stenosis, which is a well-established surrogate marker for stroke risk. In addition, Doppler US is the primary imaging modality for surveillance of patients following carotid intervention with endarterectomy or stent placement. This article reviews the pathophysiology and epidemiology of stroke, technique for performing a carotid US examination, normal findings, and diagnostic US criteria for evaluating carotid plaque, grading stenosis in the native ICA and following intervention, as well as waveform analysis of the carotid arteries., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Objective: To determine if a novel computer-generated metric, effective acceleration time, improves accuracy for detecting tardus parvus waveforms on spectral Doppler ultrasound., Methods: Patients with echocardiography-confirmed aortic valve stenosis ( n  = 132; 60 mild, 44 moderate, 28 severe) and matched controls ( n  = 48) who underwent carotid Doppler ultrasound were identified through an imaging database search at a single medical center. A custom-built spectral analysis computer program generated effective acceleration time values for spectral Doppler waveforms in the carotid arteries and a receiver operating characteristic analysis was performed to determine the optimal median effective acceleration time cutoff value to detect tardus parvus waveforms. Two radiologists, blinded to subject disease status, reviewed and rated all carotid sonograms for presence of tardus parvus waveforms. Inter-rater variability was measured, and the accuracy of aortic valve stenosis detection with and without use of the effective acceleration time cutoff was calculated., Results: Receiver operating characteristic analysis revealed an optimal effective acceleration time cutoff of ≥ 48 ms with a corresponding area under the curve of 0.77 (95% CI: 0.70-0.84). Use of the effAT cutoff demonstrated an accuracy of 74%. Accuracy of visual waveform interpretation by raters ranged from 43% to 61%. Inter-rater agreement in detection of tardus parvus waveforms was 76% (136/180 cases, K  = 0.44, p  < 0.001)., Conclusions: Detection of tardus parvus waveforms through visual interpretation of spectral Doppler waveform morphology is limited by low accuracy and moderate inter-rater variability. Use of a computer-generated median effective acceleration time cutoff value markedly improves diagnostic accuracy and avoids observer variability.

Lung cancer is the most common cause of cancer-related death globally. As a preventive measure, the United States Preventive Services Task Force (USPSTF) recommends annual screening of high risk individuals with low-dose computed tomography (CT). The resulting volume of CT scans from millions of people will pose a significant challenge for radiologists to interpret. To fill this gap, computer-aided detection (CAD) algorithms may prove to be the most promising solution. A crucial first step in the analysis of lung cancer screening results using CAD is the detection of pulmonary nodules, which may represent early-stage lung cancer. The objective of this work is to develop and validate a reinforcement learning model based on deep artificial neural networks for early detection of lung nodules in thoracic CT images. Inspired by the AlphaGo system, our deep learning algorithm takes a raw CT image as input and views it as a collection of states, and output a classification of whether a nodule is present or not. The dataset used to train our model is the LIDC/IDRI database hosted by the lung nodule analysis (LUNA) challenge. In total, there are 888 CT scans with annotations based on agreement from at least three out of four radiologists. As a result, there are 590 individuals having one or more nodules, and 298 having none. Our training results yielded an overall accuracy of 99.1% [sensitivity 99.2%, specificity 99.1%, positive predictive value (PPV) 99.1%, negative predictive value (NPV) 99.2%]. In our test, the results yielded an overall accuracy of 64.4% (sensitivity 58.9%, specificity 55.3%, PPV 54.2%, and NPV 60.0%). These early results show promise in solving the major issue of false positives in CT screening of lung nodules, and may help to save unnecessary follow-up tests and expenditures.

Carotid endarterectomy and carotid artery stenting are among the most common peripheral vascular procedures performed worldwide. Sonography is the initial and often only imaging modality used in the evaluation of iatrogenic carotid arterial injuries. This pictorial essay provides an overview of the clinical and sonographic findings of complications after interventions in the extracranial carotid arteries, including dissection, fluid collections, pseudoaneurysm, thrombosis, thromboembolism, restenosis, and stent deformation. Grayscale, color, and pulsed Doppler imaging findings are reviewed, and correlations with computed tomography, magnetic resonance imaging, and angiography are provided., (© 2017 by the American Institute of Ultrasound in Medicine.)

Objective: The purpose of this study was to assess the importance of relative value unit (RVU) flow and other factors in report turnaround time (TAT) in emergency radiologic operations., Materials and Methods: RVU flow was defined as the normalized (to 60 minutes) total work RVUs for studies performed in a given time interval of 30 minutes (RVU flow 30) or 60 minutes (RVU flow 60). Twenty-five weekday emergency radiology shifts each for four radiologists were randomly selected. The institutional radiology search engine was queried to obtain the following data for each study: study completion time, work RVU, attending radiologist, and report TAT. RVU flow 30, RVU flow 60, presence of resident, and number of hours since start of shift were computed. Two separate multiple linear regression analyses were performed with RVU flow 30 or RVU flow 60 and other factors as independent variables and TAT as the dependent variable., Results: The study included 7378 radiology studies from 100 weekday shifts, from which 1537 RVU flow 30 and 792 RVU flow 60 data points were generated. RVU flow 60 (p = 0.0026) and RVU flow 30 (< 0.0001) were significantly associated with radiology report TAT. One attending radiologist had statistically significant lower TAT 30 and TAT 60, whereas another had a lower TAT 30 but not TAT 60. The presence of a resident was significantly associated with reduced TAT 30 (p = 0.0005) and TAT 60 (p = 0.0028)., Conclusion: RVU flow 60, RVU flow 30, specific attending radiologist, and presence of a resident are significantly correlated with radiology report TAT. RVU flow should be considered when evaluating radiologist and overall system performance with respect to report TAT.

Purpose To determine if a reduced-dose computed tomography (CT) protocol could effectively help to identify patients in the emergency department (ED) with moderate to high likelihood of calculi who would require urologic intervention within 90 days. Materials and Methods The study was approved by the institutional review board and written informed consent with HIPAA authorization was obtained. This was a prospective, single-center study of patients in the ED with moderate to high likelihood of ureteral stone undergoing CT imaging. Objective likelihood of ureteral stone was determined by using the previously derived and validated STONE clinical prediction rule, which includes five elements: sex, timing, origin, nausea, and erythrocytes. All patients with high STONE score (STONE score, 10-13) underwent reduced-dose CT, while those with moderate likelihood of ureteral stone (moderate STONE score, 6-9) underwent reduced-dose CT or standard CT based on clinician discretion. Patients were followed to 90 days after initial imaging for clinical course and for the primary outcome of any intervention. Statistics are primarily descriptive and are reported as percentages, sensitivities, and specificities with 95% confidence intervals. Results There were 264 participants enrolled and 165 reduced-dose CTs performed; of these participants, 108 underwent reduced-dose CT alone with complete follow-up. Overall, 46 of 264 (17.4%) of patients underwent urologic intervention, and 25 of 108 (23.1%) patients who underwent reduced-dose CT underwent a urologic intervention; all were correctly diagnosed on the clinical report of the reduced-dose CT (sensitivity, 100%; 95% confidence interval: 86.7%, 100%). The average dose-length product for all standard-dose CTs was 857 mGy · cm ± 395 compared with 101 mGy · cm ± 39 for all reduced-dose CTs (average dose reduction, 88.2%). There were five interventions for nonurologic causes, three of which were urgent and none of which were missed when reduced-dose CT was performed. Conclusion A CT protocol with over 85% dose reduction can be used in patients with moderate to high likelihood of ureteral stone to safely and effectively identify patients in the ED who will require urologic intervention. (©) RSNA, 2016 Online supplemental material is available for this article.

Study Objective: Reduced-dose computed tomography (CT) scans have been recommended for diagnosis of kidney stone but are rarely used in the emergency department (ED) setting. Test characteristics are incompletely characterized, particularly in obese patients. Our primary outcome is to determine the sensitivity and specificity of a reduced-dose CT protocol for symptomatic ureteral stones, particularly those large enough to require intervention, using a protocol stratified by patient size., Methods: This was a prospective, blinded observational study of 201 patients at an academic medical center. Consenting subjects underwent both regular- and reduced-dose CT, stratified into a high and low body mass index (BMI) protocol based on effective abdominal diameter. Reduced-dose CT scans were interpreted by radiologists blinded to regular-dose interpretations. Follow-up for outcome and intervention was performed at 90 days., Results: CT scans with both regular and reduced doses were conducted for 201 patients, with 63% receiving the high BMI reduced-dose protocol. Ureteral stone was identified in 102 patients (50.7%) of those receiving regular-dose CT, with a ureteral stone greater than 5 mm identified in 26 subjects (12.9%). Sensitivity of the reduced-dose CT for any ureteral stone was 90.2% (95% confidence interval [CI] 82.3% to 95.0%), with a specificity of 99.0% (95% CI 93.7% to 100.0%). For stones greater than 5 mm, sensitivity was 100% (95% CI 85.0% to 100.0%). Reduced-dose CT identified 96% of patients who required intervention for ureteral stone within 90 days. Mean reduction in size-specific dose estimate was 18.6 milligray (mGy), from 21.7 mGy (SD 9.7) to 3.4 mGy (SD 0.9)., Conclusion: CT with substantial dose reduction was 90.2% (95% CI 82.3% to 95.0%) sensitive and 98.9% (95% CI 85.0% to 100.0%) specific for ureteral stones in ED patients with a wide range of BMIs. Reduced-dose CT was 96.0% (95% CI 80.5% to 99.3%) sensitive for ureteral stones requiring intervention within 90 days., (Copyright © 2014 American College of Emergency Physicians. Published by Elsevier Inc. All rights reserved.)

Peripheral arterial disease (PAD) is an important manifestation of atherosclerosis, with an estimated age-adjusted prevalence of approximately 13% in people older than 50 years. Noninvasive vascular laboratory physiologic studies are indispensable tools in the initial evaluation and workup and postintervention follow-up. In this review, we describe a practical approach to the technique, interpretation, pitfalls, and limitations of these physiologic studies. We also provide an algorithmic approach for using these studies in the initial workup of patients with suspected PAD. Noninvasive techniques that primarily provide anatomic information have not been included in this review., (Published by Elsevier Inc.)

Carotid artery dissection is a rare but potentially serious complication of endovascular procedures in the carotid arteries. Stent deformation or incomplete expansion may occur following endovascular repair of an iatrogenic carotid artery dissection and may mimic stent fracture. We report an unusual case of deformation of a common carotid artery open cell design stent following endovascular repair of an iatrogenic dissection, which resulted in persistent blood flow between the stent and the wall of the common carotid artery. Sonographic features are described and correlation with intravascular ultrasound and CT is provided.

Purpose: To determine radiation dose indexes for computed tomography (CT) performed with renal colic protocols in the United States, including frequency of reduced-dose technique usage and any institutional-level factors associated with high or low dose indexes., Materials and Methods: The Dose Imaging Registry (DIR) collects deidentified CT data, including examination type and dose indexes, for CT performed at participating institutions; thus, the DIR portion of the study was exempt from institutional review board approval and was HIPAA compliant. CT dose indexes were examined at the institutional level for CT performed with a renal colic protocol at institutions that contributed at least 10 studies to the registry as of January 2013. Additionally, patients undergoing CT for renal colic at a single institution (with institutional review board approval and informed consent from prospective subjects and waiver of consent from retrospective subjects) were studied to examine individual renal colic CT dose index patterns and explore relationships between patient habitus, demographics, and dose indexes. Descriptive statistics were used to analyze dose indexes, and linear regression and Spearman correlations were used to examine relationships between dose indexes and institutional factors., Results: There were 49 903 renal colic protocol CT examinations conducted at 93 institutions between May 2011 and January 2013. Mean age ± standard deviation was 49 years ± 18, and 53.9% of patients were female. Institutions contributed a median of 268 (interquartile range, 77-699) CT studies. Overall mean institutional dose-length product (DLP) was 746 mGy ⋅ cm (effective dose, 11.2 mSv), with a range of 307-1497 mGy ⋅ cm (effective dose, 4.6-22.5 mSv) for mean DLPs. Only 2% of studies were conducted with a DLP of 200 mGy ⋅ cm or lower (a "reduced dose") (effective dose, 3 mSv), and only 10% of institutions kept DLP at 400 mGy ⋅ cm (effective dose, 6 mSv) or less in at least 50% of patients., Conclusion: Reduced-dose renal protocol CT is used infrequently in the United States. Mean dose index is higher than reported previously, and institutional variation is substantial.

Acute complications arising in abdominopelvic malignancies represent a unique subset of patients presenting to the emergency room. The acute presentation can be due to complications occurring in the tumor itself or visceral or vascular structures harboring the tumor. Multidetector computed tomography (MDCT) is the investigation of choice in the workup of these patients and enables appropriate and timely management. Management of the complication depends primarily on the extent of the underlying malignancy and the involvement of other viscera. The purpose of this article is to depict the imaging features of these complications on MDCT.

There is an increasing incidence of both intra- and extra-thoracic manifestations of tuberculosis, in part due to the AIDS epidemic. Isolated tubercular involvement of the solid abdominal viscera is relatively unusual. Cross-sectional imaging with ultrasound, multidetector computed tomography (CT), and magnetic resonance imaging (MRI) plays an important role in the diagnosis and post treatment follow-up of tuberculosis. Specific imaging features of tuberculosis are frequently related to caseous necrosis, which is the hallmark of this disease. However, depending on the type of solid organ involvement, tubercular lesions can mimic a variety of neoplastic and nonneoplastic conditions. Often, cross-sectional imaging alone is insufficient in reaching a conclusive diagnosis, and image-guided tissue sampling is needed. In this article, we review the pathology and cross-sectional imaging features of tubercular involvement of solid abdominopelvic organs with a special emphasis on appropriate differential diagnoses.

Background: Perforated jejunal diverticulitis is an unusual entity that can present with acute abdominal pain. Due to the non-specific clinical findings, this condition is rarely diagnosed clinically., Case Report: We present the case of a 75-year-old man in whom a perforated jejunal diverticulitis complicated by abscess formation was diagnosed by computed tomography (CT). He underwent a laparotomy with resection of the involved jejunal segment. He had an uneventful recovery and was subsequently discharged., Conclusions: This case report demonstrates the utility of CT in accurately diagnosing this unusual entity that frequently perplexes clinicians., (Copyright © 2013 Elsevier Inc. All rights reserved.)

The arteries of the upper extremities are increasingly utilized to gain access for angiography, percutaneous coronary interventions, endovascular therapy, and continuous hemodynamic monitoring. Hence, complications after upper-extremity arterial interventions are increasing in incidence. Similarly, the incidence of upper-extremity deep venous thrombosis is increasing as venous access is increasingly achieved with upper-extremity central line placement. Knowledge of the sonographic appearance of these complications is essential as ultrasound is often the only imaging modality used in the evaluation of suspected vascular injury. This pictorial review demonstrates the spectrum of complications observed following vascular procedures in the upper extremities, including thrombosis, hematoma, pseudoaneurysm, arteriovenous fistula, and arterial dissection. Gray-scale, color, and pulsed Doppler imaging findings are described, and pertinent management issues, including endovascular and surgical therapies, are briefly discussed.

Hemangiomas are a radiologist's dream lesions because they allow a confident diagnosis most of the time. However, within the abdomen, hemangiomas may occur in such atypical locations and can have such unusual features that they cause significant diagnostic dilemma and may end up being excised surgically. The literature is replete with isolated case reports of atypical hemangiomas in the abdominal cavity, and, to our knowledge, so far, there is no comprehensive review. We present, in this article, a pictorial review of a gamut of uncommon hemangiomas and hemangiomatosis syndromes. Knowledge of these rare types can help in limiting diagnostic errors and increase the confidence of radiologists, thus avoiding unnecessary surgeries., (Copyright © 2013 Canadian Association of Radiologists. Published by Elsevier Inc. All rights reserved.)

Recent advances in radiology have greatly increased the ability to make highly accurate diagnosis. Biopsy of many commonly seen lesions is no longer performed as the radiological findings are pathognomonic. This gives rise to the concept of 'virtual biopsy', a term coined on the lines of other imaging techniques such as virtual colonoscopy. Virtual biopsy is not a new imaging technique but a new concept which refers to the use of existing imaging modalities to evaluate the morphological features of tumors and arriving at a non-invasive diagnosis with a high degree of confidence obviating the need for true biopsy. Elements of virtual biopsy have already been incorporated into some evidence-based guidelines, and it is expected that with further technological advancements, an increasing number of tumors may be diagnosed and managed accordingly. A wider acceptance of virtual biopsy could further reduce the need for invasive biopsies and its attendant costs and risks. In this review article, we use index cases to further emphasize this concept.

Transcranial Doppler ultrasonography (US) is a noninvasive, portable technique for evaluating the intracranial vasculature. It has found its most useful clinical application in the detection of vasospasm involving the cerebral vessels after subarachnoid hemorrhage due to aneurysm rupture. The technique has become an integral part of monitoring and managing patients with subarachnoid hemorrhage in the neurologic intensive care unit. In addition, it has proved useful for evaluating the intracranial vasculature in patients with sickle cell disease, stroke, or brain death. Transcranial US originated as a "blind" nonimaging study in which pulsed Doppler technology was used. Identification of the major intracranial vessels and evaluation of those vessels for vasospasm relied on spectral waveforms obtained in each vessel and was based on the depth of the vessel from the skull, the direction of blood flow, and the orientation of the transducer. Recent advances in US technology allow the use of gray-scale, spectral Doppler, and color Doppler flow imaging to directly visualize intracranial vessels, thereby simplifying flow velocity measurements and enhancing their accuracy for vasospasm detection. In particular, measurements of peak systolic velocity and mean flow velocity and calculation of the Lindegaard ratio facilitate the identification of vessels that may be in vasospasm and help differentiate vasospasm from physiologic conditions such as hyperemia and autoregulation. Thus, gray-scale and color Doppler flow imaging offer many advantages over the original pulsed Doppler technique for evaluating the intracranial vasculature.

Purpose: The purpose of this study was to review the etiology and computed tomography (CT) findings of small-bowel obstruction (SBO) in patients who have undergone bariatric laparoscopic Roux-en-Y gastric bypass (LGBP) surgery., Materials and Methods: Prospectively entered data from a surgical database of 835 consecutive patients who underwent antecolic-antegastric LGBP for morbid obesity from June 1999 to April 2005 in a single institution were retrospectively reviewed. A total of 42 cases of bowel obstruction were observed in 41 patients. Surgical proof was available in 38 cases, and 4 cases had characteristic imaging features and/or clinical follow-up. Seventeen CT scans were reviewed to determine cause and level of obstruction, and this was correlated with surgical findings and clinical follow-up., Results: Internal hernia was the most common (13 cases) and also the most frequently missed etiology of SBO on CT scans, with the diagnosis being made prospectively in only 2 of 6 cases, in which CT was done. Adhesions, ventral hernia, postoperative ileus, and jejunojejunal (JJ) anastomotic strictures, in that order, were the other commonly observed etiologies for SBO, with 11, 7, 5, and 4 cases, respectively. Some causes of SBO post-LGBP (JJ anastomotic stricture and postoperative ileus) developed relatively early, whereas others (internal hernia) tended to develop later or had a bimodal distribution (adhesions and ventral hernia). Fifteen (36%) of 42 cases had SBO at or near the level of jejunojejunostomy site; causes included internal hernia (5 cases), adhesions/kinking of small bowel (5 cases), JJ anastomotic stricture (4 cases), and JJ intussusception (1 case)., Conclusion: The time interval between LGBP and development of SBO might provide a useful clinical clue to its etiology. The JJ level is an important location for SBO post-LGBP because of a variety of causes, and special attention must be paid to this site at imaging of post-LGBP patients.

We report a case of a ruptured cyst in a hyperstimulated ovary that was initially misinterpreted as ovarian hyperstimulation syndrome (OHSS). A 22-year-old woman who was on oral clomiphene citrate for primary infertility presented with pain in the lower abdomen, hypotension, and tachycardia. Sonographic examination revealed multiple cysts in both ovaries and free fluid in the abdomen, and the initial diagnosis was OHSS. However, sonographically guided aspiration of free fluid revealed a hemoperitoneum, and the patient underwent emergent surgery. At laparotomy, an actively bleeding ruptured cyst in a hyperstimulated ovary was found to be the cause of the hemoperitoneum. Radiologists must be familiar with the imaging features of this condition to avoid misdiagnosing it as OHSS, because this could potentially delay urgently required surgery.

Purpose: To evaluate the results of radiofrequency ablation in treating hepatic metastases from breast cancer., Materials and Methods: Fourteen breast cancer patients with 16 hepatic metastases measuring 1.1 to 4.0 cm in the longest axis (mean, 1.9 cm) were prospectively studied. All patients had previously received chemotherapy. Radiofrequency ablation was done using 17-G, internally cooled electrodes under ultrasound guidance. A single index tumor was treated in 12 patients, and two tumors each were treated in two patients. Follow-up was done using serial computed tomography for a duration ranging from 6 to 45 months (mean, 18 months; median, 16 months)., Results: All patients were treated in a single session. No major complications occurred. Minor complications or side effects (asymptomatic pleural effusion, perihepatic fluid collection) were observed in three patients. Complete necrosis, defined as an absence of detectable disease on computed tomography at 6 months follow-up was achieved in 14 (88%) of 16 index tumors. Treatment failure due to the development of new metastases was observed in seven (50%) of 14 patients. Five (36%) patients died in the first 12 months after radiofrequency ablation due to the development of new hepatic and extrahepatic metastases. At the time of writing, nine (64%) of 14 patients are alive, of whom four patients (29%) are disease-free and three patients (21%) are progression-free., Conclusions: A high overall treatment failure rate (50%) was observed due to the development of new metastases on follow-up. Despite this, radiofrequency ablation appears to be a safe and effective adjunct to systemic chemotherapy for the loco-regional treatment of liver metastases from breast cancer.

The incidence of metastases from basal cell carcinoma is rare. We report a 66-year-old woman who had basal cell carcinoma of the outer canthus of the left eye. Six months following radical radiotherapy, she developed local recurrence for which an orbital exenteration was done. Four months later, she developed rapidly-progressive multiple skeletal metastases and died soon after.