Doppler Ultrasound of the Renal Vasculature.

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.

Pitfalls in Carotid Doppler Interpretation and How to Avoid Them.

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.

MR Imaging Biomarkers for the Prediction of Outcome after Radiofrequency Ablation of Hepatocellular Carcinoma: Qualitative and Quantitative Assessments of the Liver Imaging Reporting and Data System and Radiomic Features.

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.

A pictorial review of non-traumatic adrenergic crisis.

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.

Accessible Personal Ultrasound Training Simulator.

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.

Sonographic Evaluation of Complications of Extracranial Carotid Artery Interventions.

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.

Effect of Radiology Study Flow on Report Turnaround Time.

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.

Ureteral Stones: Implementation of a Reduced-Dose CT Protocol in Patients in the Emergency Department with Moderate to High Likelihood of Calculi on the Basis of STONE Score.

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.

Accuracy of reduced-dose computed tomography for ureteral stones in emergency department patients.

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.

Radiation dose index of renal colic protocol CT studies in the United States: a report from the American College of Radiology National Radiology Data Registry.

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.

Carotid stent deformation: sonographic findings and CT correlation.

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.

Deferral of Estimated Glomerular Filtration Rate Testing Before Contrast-Enhanced CT in Low-Risk Emergency Department Patients: Assessment of Safety and Impact on Throughput.

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 m2 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 m2. 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.

Timely diagnosis of perforated jejunal diverticulitis by computed tomography.

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.

Abdominal hemangiomas: a pictorial review of unusual, atypical, and rare types.

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.

Ultrasound Evaluation of Chronic Venous Insufficiency.

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.

Ultrasound Image Optimization for the Interventional Radiologist.

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.

Safety and Efficacy of Percutaneous Cholecystostomy for Emphysematous Cholecystitis.

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 6th 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.

Small-bowel obstruction after laparoscopic Roux-en-Y gastric bypass surgery.

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.

Carotid Ultrasound.

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.