LI-RADS Treatment Response Algorithm: Performance and Diagnostic Accuracy.

Background In 2017, the Liver Imaging Reporting and Data System (LI-RADS) included an algorithm for the assessment of hepatocellular carcinoma (HCC) treated with local-regional therapy. The aim of the algorithm was to enable standardized evaluation of treatment response to guide subsequent therapy. However, the performance of the algorithm has not yet been validated in the literature. Purpose To evaluate the performance of the LI-RADS 2017 Treatment Response algorithm for assessing the histopathologic viability of HCC treated with bland arterial embolization. Materials and Methods This retrospective study included patients who underwent bland arterial embolization for HCC between 2006 and 2016 and subsequent liver transplantation. Three radiologists independently assessed all treated lesions by using the CT/MRI LI-RADS 2017 Treatment Response algorithm. Radiology and posttransplant histopathology reports were then compared. Lesions were categorized on the basis of explant pathologic findings as either completely (100%) or incompletely (<100%) necrotic, and performance characteristics and predictive values for the LI-RADS Treatment Response (LR-TR) Viable and Nonviable categories were calculated for each reader. Interreader association was calculated by using the Fleiss κ. Results A total of 45 adults (mean age, 57.1 years ± 8.2; 13 women) with 63 total lesions were included. For predicting incomplete histopathologic tumor necrosis, the accuracy of the LR-TR Viable category for the three readers was 60%-65%, and the positive predictive value was 86%-96%. For predicting complete histopathologic tumor necrosis, the accuracy of the LR-TR Nonviable category was 67%-71%, and the negative predictive value was 81%-87%. By consensus, 17 (27%) of 63 lesions were categorized as LR-TR Equivocal, and 12 of these lesions were incompletely necrotic. Interreader association for the LR-TR category was moderate (κ = 0.55; 95% confidence interval: 0.47, 0.67). Conclusion The Liver Imaging Reporting and Data System 2017 Treatment Response algorithm had high predictive value and moderate interreader association for the histopathologic viability of hepatocellular carcinoma treated with bland arterial embolization when lesions were assessed as Viable or Nonviable. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Gervais in this issue.

Repeat CT Performed Within One Month of CT Conducted in the Emergency Department for Abdominal Pain: A Secondary Analysis of Data From a Prospective Multicenter Study.

OBJECTIVE: The purpose of this study is to determine both the frequency of repeat CT performed within 1 month after a patient visits the emergency department (ED) and undergoes CT evaluation for abdominal pain and the frequency of worsened or new CT-based diagnoses. SUBJECTS AND METHODS: Secondary analysis was performed on data collected during a prospective multicenter study. The parent study included patients who underwent CT in the ED for abdominal pain between 2012 and 2014, and these patients constituted the study group of the present analysis. The proportion of patients who underwent (in any setting) repeat abdominal CT within 1 month of the index CT examination was calculated. For each of these patients, results of the index and repeat CT scans were compared by an independent panel and categorized as follows: no change (group 1); same process, improved (group 2); same process, worse (group 3); or different process (group 4). The proportion of patients in groups 1 and 2 versus groups 3 and 4 was calculated, and patient and ED physician characteristics were compared. RESULTS: The parent study included 544 patients (246 of whom were men [45%]; mean patient age, 49.4 years). Of those 544 patients, 53 (10%; 95% CI, 7.5-13%) underwent repeat abdominal CT. Patients' CT comparisons were categorized as follows: group 1 for 43% of patients (23/53), group 2 for 26% (14/53), group 3 for 15% (8/53), and group 4 for 15% (8/53). New or worse findings were present in 30% of patients (16/53) (95% CI, 19-44%). When patients with findings in groups 1 and 2 were compared to patients with findings in groups 3 and 4, no significant difference was noted in patient age (p = 0.25) or sex (p = 0.76), the number of days between scans (p = 0.98), and the diagnostic confidence of the ED physician after the index CT scan was obtained (p = 0.33). CONCLUSION: Short-term, repeat abdominal CT was performed for 10% of patients who underwent CT in the ED for abdominal pain, and it yielded new or worse findings for 30% of those patients.

Comparison of Visualization Rates of LI-RADS Version 2014 Major Features With IV Gadobenate Dimeglumine or Gadoxetate Disodium in Patients at Risk for Hepatocellular Carcinoma.

OBJECTIVE: The purpose of this study is to compare visualization rates of the major features covered by Liver Imaging Reporting and Data System (LI-RADS) version 2014 in patients at risk for hepatocellular carcinoma using either gadobenate dimeglumine or gadoxetate disodium IV contrast agent. MATERIALS AND METHODS: This retrospective study included liver MRI examinations performed with either gadobenate dimeglumine or gadoxetate disodium contrast enhancement. Using age, sex, underlying liver disease, and presence of cirrhosis, patients were placed into matched cohorts. All hepatic nodules 1 cm or larger (up to five per subject) were included, resulting in 63 subjects with 130 nodules (median nodule size, 1.9 cm) imaged with gadobenate and 64 subjects with 117 nodules (median nodule size, 2.0 cm) imaged with gadoxetate. Three radiologists reviewed the studies for LI-RADS major features independently. Bootstrap resampling with 10,000 repetitions was used to compare feature detection rates. RESULTS: Arterial phase hyperenhancement was seen in a similar number of nodules with gadobenate dimeglumine (mean, 91.5% [119/130]) and gadoxetate disodium (mean, 88.0% [103/117]) (p = 0.173). Dynamic phase washout was more commonly seen with gadobenate dimeglumine (mean, 60.2% [78.3/130]) than with gadoxetate disodium (mean, 45.3% [53/117]) (p = 0.006). The capsule feature was more often visualized with gadobenate dimeglumine (mean, 50.2% [65.3/130]) than with gadoxetate disodium (mean, 33.3% [39/117]) (p < 0.001). Interreader agreement for arterial phase enhancement and dynamic phase washout was almost perfect for both contrast agents (κ > 0.83). Agreement for the capsule feature was moderate for gadobenate dimeglumine (κ = 0.52) and substantial for gadoxetate disodium (κ = 0.67). CONCLUSION: The rates of visualization of arterial phase hyperenhancement are similar in studies performed with gadobenate dimeglumine and gadoxetate disodium, but dynamic phase washout and capsule appearance are more commonly visualized with gadobenate dimeglumine.

Intravenous Gadoxetate Disodium Administration Reduces Breath-holding Capacity in the Hepatic Arterial Phase: A Multi-Center Randomized Placebo-controlled Trial.

Purpose To determine, in a multicenter double-blinded placebo-controlled trial, whether maximal hepatic arterial phase breath-holding duration is affected by gadoxetate disodium administration. Materials and Methods Institutional review board approval was obtained for this prospective multi-institutional HIPAA-compliant study; written informed consent was obtained from all subjects. At three sites, a total of 44 volunteers underwent a magnetic resonance (MR) imaging examination in which images were acquired before and dynamically after bolus injection of gadoxetate disodium, normal saline, and gadoterate meglumine, administered in random order in a single session. The technologist and volunteer were blinded to the agent. Arterial phase breath-holding duration was timed after each injection, and volunteers reported subjective symptoms. Heart rate (HR) and oxygen saturation were monitored. Images were independently analyzed for motion artifacts by three radiologists. Arterial phase breath-holding duration and motion artifacts after each agent were compared by using the Mann-Whitney U test and the McNemar test. Factors affecting the above outcomes were assessed by using a univariate, multivariable model. Results Arterial phase breath holds were shorter after gadoxetate disodium (mean, 32 seconds ± 19) than after saline (mean, 40 seconds ± 17; P < .001) or gadoterate meglumine (43 seconds ± 21, P < .001) administration. In 80% (35 of 44) of subjects, arterial phase breath holds were shorter after gadoxetate disodium than after both saline and gadoterate meglumine. Three (7%) of 44 volunteers had severe arterial phase motion artifacts after gadoxetate disodium administration, one (2%; P = .62) had them after gadoterate meglumine administration, and none (P = .25) had them after saline administration. HR and oxygen saturation changes were not significantly associated with contrast agent. Conclusion Maximal hepatic arterial phase breath-holding duration is reduced after gadoxetate disodium administration in healthy volunteers, and reduced breath-holding duration is associated with motion artifacts. © RSNA, 2016.

Role of CT in the Diagnosis of Nonspecific Abdominal Pain: A Multicenter Analysis.

OBJECTIVE: The objective of our study was to determine whether specific patient and physician factors-known before CT-are associated with a diagnosis of nonspecific abdominal pain (NSAP) after CT in the emergency department (ED). MATERIALS AND METHODS: We analyzed data originally collected in a prospective multicenter study. In the parent study, we identified ED patients referred to CT for evaluation of abdominal pain. We surveyed their physicians before and after CT to identify changes in leading diagnoses, diagnostic confidence, and admission decisions. In the current study, we conducted a multiple regression analysis to identify whether the following were associated with a post-CT diagnosis of NSAP: patient age; patient sex; physicians' years of experience; physicians' pre-CT diagnostic confidence; and physicians' pre-CT admission decision if CT had not been available. We analyzed patients with and those without a pre-CT diagnosis of NSAP separately. For the sensitivity analysis, we excluded patients with different physicians before and after CT. RESULTS: In total, 544 patients were included: 10% (52/544) with a pre-CT diagnosis of NSAP and 90% (492/544) with a pre-CT diagnosis other than NSAP. The leading diagnoses changed after CT in a large proportion of patients with a pre-CT diagnosis of NSAP (38%, 20/52). In regression analysis, we found that physicians' pre-CT diagnostic confidence was inversely associated with a post-CT diagnosis of NSAP in patients with a pre-CT diagnosis other than NSAP (p = 0.0001). No other associations were significant in both primary and sensitivity analyses. CONCLUSION: With the exception of physicians' pre-CT diagnostic confidence, the factors evaluated were not associated with a post-CT diagnosis of NSAP.

Emergency Neurological Life Support: Third Edition, Updates in the Approach to Early Management of a Neurological Emergency.

Emergency Neurologic Life Support (ENLS) is an educational program designed to provide users advisory instructions regarding management for the first few hours of a neurologic emergency. The content of the course is divided into 14 modules, each addressing a distinct category of neurological injury. The course is appropriate for practitioners and providers from various backgrounds who work in environments of variable medical complexity. The focus of ENLS is centered on a standardized treatment algorithm, checklists, to guide early patient care, and a structured format for communication of findings and concerns to other healthcare professionals. Certification and training in ENLS is hosted by the Neurocritical Care Society. This document introduces the concept of ENLS and describes revisions that constitute the third version.

Changes in Physician Decision Making after CT: A Prospective Multicenter Study in Primary Care Settings.

Purpose To determine the effect of computed tomography (CT) results on physician decision making in three common clinical scenarios in primary care. Materials and Methods This research was approved by the institutional review board (IRB) and was HIPAA compliant. All physicians consented to participate with an opt-in or opt-out mechanism; patient consent was waived with IRB approval. In this prospective multicenter observational study, outpatients referred by primary care providers (PCPs) for CT evaluation of abdominal pain, hematuria, or weight loss were identified. Prior to CT, PCPs were surveyed to elicit their leading diagnosis, confidence in that diagnosis (confidence range, 0%-100%), a rule-out diagnosis, and a management plan if CT were not available. Surveys were repeated after CT. Study measures were the proportion of patients in whom leading diagnoses and management changed (PCP management vs specialist referral vs emergency department transfer), median changes in diagnostic confidence, and the proportion of patients in whom CT addressed rule-out diagnoses. Regression analyses were used to identify associations between study measures and site and participant characteristics. Specifically, logistic regression analysis was used for binary study measures (change in leading diagnosis, change in management), and linear regression analysis was used for the continuous study measure (change in diagnostic confidence). Accrual began on September 5, 2012, and ended on June 28, 2014. Results In total, 91 PCPs completed pre- and post-CT surveys in 373 patients. In patients with abdominal pain, hematuria, or weight loss, leading diagnoses changed after CT in 53% (131 of 246), 49% (36 of 73), and 57% (27 of 47) of patients, respectively. Management changed in 35% (86 of 248), 27% (20 of 74), and 54% (26 of 48) of patients, respectively. Median absolute changes in diagnostic confidence were substantial and significant (+20%, +20%, and +19%, respectively; P ≤ .001 for all); median confidence after CT was high (90%, 88%, and 80%, respectively). PCPs reported CT was helpful in confirming or excluding rule-out diagnoses in 98% (184 of 187), 97% (59 of 61), and 97% (33 of 34) of patients, respectively. Significant associations between primary measures and site and participant characteristics were not identified. Conclusion Changes in PCP leading diagnoses and management after CT were common, and diagnostic confidence increased substantially. © RSNA, 2016 Online supplemental material is available for this article.

CT in the Emergency Department: A Real-Time Study of Changes in Physician Decision Making.

PURPOSE: To determine how physicians' diagnoses, diagnostic uncertainty, and management decisions are affected by the results of computed tomography (CT) in emergency department settings. MATERIALS AND METHODS: This study was approved by the institutional review board and compliant with HIPAA. Data were collected between July 12, 2012, and January 13, 2014. The requirement to obtain patient consent was waived. In this prospective, four-center study, patients presenting to the emergency department who were referred for CT with abdominal pain, chest pain and/or dyspnea, or headache were identified. Physicians were surveyed before and after CT to determine the leading diagnosis, diagnostic confidence (on a scale of 0% to 100%), alternative "rule out" diagnosis, and management decisions. Primary measures were the proportion of patients for whom the leading diagnosis or admission decision changed and median changes in diagnostic confidence. Secondary measures addressed alternative diagnoses and return-to-care visits (eg, to emergency department) at 1-month follow-up. Regression analysis was used to identify associations between primary measures and site and participant characteristics. RESULTS: Both surveys were completed for 1280 patients by 245 physicians. The leading diagnosis changed in 235 of 460 patients with abdominal pain (51%), 163 of 387 with chest pain and/or dyspnea (42%), and 103 of 433 with headache (24%). Pre-CT diagnostic confidence was inversely associated with the likelihood of a diagnostic change (P < .0001). Median changes in confidence were substantial (increases of 25%, 20%, and 13%, respectively, for patients with abdominal pain, chest pain and/or dyspnea, and headache; P < .0001); median post-CT confidence was high (95% for all three groups). CT helped confirm or exclude at least 95% of alternative diagnoses. Admission decisions changed in 116 of 457 patients with abdominal pain (25%), 72 of 387 with chest pain and/or dyspnea (19%), and 81 of 426 with headache (19%). During follow-up, 70 of 450 patients with abdominal pain (15%), 53 of 387 with chest pain and/or dyspnea (14%), and 49 of 433 with headache (11%) returned for the same indication. In general, changes in leading diagnosis, diagnostic confidence, and admission decisions were not well explained with site or participant characteristics. CONCLUSION: Physicians' diagnoses and admission decisions changed frequently after CT, and diagnostic uncertainty was alleviated.

Impact of Infection on Stroke Morbidity and Outcomes.

Each year, millions of persons worldwide are disabled by stroke. The burden of stroke is expected to increase as a consequence of growth in our elderly population. Outcome is dependent upon limitation of secondary medical processes in the acute setting that lead to deterioration and increased long-term disability. The prevalence of infection after stroke is greater that seen in other medical conditions with similar acuity and its impact upon morbidity and mortality is substantial. Physical impairment and immune modulation are chief determinants in rate of infection after stroke. Each of these factors has been a target for therapeutic intervention. Current best practices for acute stroke management implement strategies for prevention, prompt identification, and treatment of infection. Novel therapies are currently being explored which have the opportunity to greatly minimize infectious complications following stroke. Fever commonly accompanies infection and independently influences stroke outcome. Targeted temperature management provides an additional chance to improve stroke recovery.

Emergency Neurological Life Support: Traumatic Brain Injury.

Traumatic Brain Injury (TBI) was chosen as an Emergency Neurological Life Support topic due to its frequency, the impact of early intervention on outcomes for patients with TBI, and the need for an organized approach to the care of such patients within the emergency setting. This protocol was designed to enumerate the practice steps that should be considered within the first critical hour of neurological injury.

Admission Leukocytosis in Intracerebral Hemorrhage: Associated Factors and Prognostic Implications.

BACKGROUND AND PURPOSE: Leukocytosis is a reaction that is usually, but not always, associated with an infectious process. There is very little data on the significance of admission leukocytosis (AL) in patients with intracerebral hemorrhage (ICH). The purpose of this study was to investigate the associated clinical and radiologic findings and prognostic significance of AL in patients with ICH. METHODS: We retrospectively reviewed the records of consecutive ICH patients admitted over a 2-year period. Key data we collected included ICH size, location, intraventricular hemorrhage (IVH), age, admission Glasgow Coma Scale (GCS0) score, peak leukocyte count and temperature in the first 24 h of hospitalization, and outcomes on discharge. Severity of IVH was calculated using the Graeb Scale. Logistic regression was performed to determine association of variables. RESULTS: In 128 consecutive ICH patients, AL was present in 41.4 %. AL was significantly associated with presence (OR 2.28, 95 % CI 1.11-4.68; p = 0.024), but not severity of IVH and with admission GCS0. Leukocyte count showed a strong association with IVH (p = 0.01) and with decreasing GCS0 (p = 0.007). There was no correlation between AL and poor outcome at discharge. There was also no evidence of infection in any patient with AL. CONCLUSION: AL in ICH patients is often non-infectious, strongly associated with the presence of IVH, but not specifically an ominous indicator for outcome. Leukocyte count has an inverse relationship with GCS0. Prospective studies are needed to confirm these findings.

Emergency Neurologic Life Support (ENLS): Evolution of Management in the First Hour of a Neurological Emergency.

Emergency neurological life support (ENLS) is an educational program designed to provide users advisory instruction regarding management for the first few hours of a neurological emergency. The content of the course is divided into 14 modules, each addressing a distinct category of neurological injury. The course is appropriate for practitioners and providers from various backgrounds who work in environments of variable medical complexity. The focus of ENLS is centered on a standardized treatment algorithm, checklists to guide early patient care, and a structured format for communication of findings and concerns to other healthcare professionals. Certification and training in ENLS is hosted by the Neurocritical Care Society. This document introduces the concept of ENLS and describes the revisions that constitute this second version.

Automated selection of abdominal MRI series using a DICOM metadata classifier and selective use of a pixel-based classifier.

Accurate, automated MRI series identification is important for many applications, including display ("hanging") protocols, machine learning, and radiomics. The use of the series description or a pixel-based classifier each has limitations. We demonstrate a combined approach utilizing a DICOM metadata-based classifier and selective use of a pixel-based classifier to identify abdominal MRI series. The metadata classifier was assessed alone as Group metadata and combined with selective use of the pixel-based classifier for predictions with less than 70% certainty (Group combined). The overall accuracy (mean and 95% confidence intervals) for Groups metadata and combined on the test dataset were 0.870 CI (0.824,0.912) and 0.930 CI (0.893,0.963), respectively. With this combined metadata and pixel-based approach, we demonstrate accurate classification of 95% or greater for all pre-contrast MRI series and improved performance for some post-contrast series.

Simplifying risk stratification for thyroid nodules on ultrasound: validation and performance of an artificial intelligence thyroid imaging reporting and data system.

PURPOSE: To validate the performance of a recently created risk stratification system (RSS) for thyroid nodules on ultrasound, the Artificial Intelligence Thyroid Imaging Reporting and Data System (AI TI-RADS). MATERIALS AND METHODS: 378 thyroid nodules from 320 patients were included in this retrospective evaluation. All nodules had ultrasound images and had undergone fine needle aspiration (FNA). 147 nodules were Bethesda V or VI (suspicious or diagnostic for malignancy), and 231 were Bethesda II (benign). Three radiologists assigned features according to the AI TI-RADS lexicon (same categories and features as the American College of Radiology TI-RADS) to each nodule based on ultrasound images. FNA recommendations using AI TI-RADS and ACR TI-RADS were then compared and sensitivity and specificity for each RSS were calculated. RESULTS: Across three readers, mean sensitivity of AI TI-RADS was lower than ACR TI-RADS (0.69 vs 0.72, p < 0.02), while mean specificity was higher (0.40 vs 0.37, p < 0.02). Overall total number of points assigned by all three readers decreased slightly when using AI TI-RADS (5,998 for AI TI-RADS vs 6,015 for ACR TI-RADS), including more values of 0 to several features. CONCLUSION: AI TI-RADS performed similarly to ACR TI-RADS while eliminating point assignments for many features, allowing for simplification of future TI-RADS versions.

Deep learning for classification of thyroid nodules on ultrasound: validation on an independent dataset.

OBJECTIVES: The purpose is to apply a previously validated deep learning algorithm to a new thyroid nodule ultrasound image dataset and compare its performances with radiologists. METHODS: Prior study presented an algorithm which is able to detect thyroid nodules and then make malignancy classifications with two ultrasound images. A multi-task deep convolutional neural network was trained from 1278 nodules and originally tested with 99 separate nodules. The results were comparable with that of radiologists. The algorithm was further tested with 378 nodules imaged with ultrasound machines from different manufacturers and product types than the training cases. Four experienced radiologists were requested to evaluate the nodules for comparison with deep learning. RESULTS: The Area Under Curve (AUC) of the deep learning algorithm and four radiologists were calculated with parametric, binormal estimation. For the deep learning algorithm, the AUC was 0.69 (95% CI: 0.64-0.75). The AUC of radiologists were 0.63 (95% CI: 0.59-0.67), 0.66 (95% CI:0.61-0.71), 0.65 (95% CI: 0.60-0.70), and 0.63 (95%CI: 0.58-0.67). CONCLUSION: In the new testing dataset, the deep learning algorithm achieved similar performances with all four radiologists. The relative performance difference between the algorithm and the radiologists is not significantly affected by the difference of ultrasound scanner.

Update on multimodality monitoring.

Brain injury is a dynamic process marked by an initial damaging insult followed by a cascade of physical, electrical, and metabolic changes capable of resulting in further patient disability. These subclinical changes should be detected at a time when therapeutic intervention is most efficacious and preemptive. Multimodality monitoring is the practice by which a variety of brain monitors are utilized to deliver care, specific to the needs of the individual patient, in an attempt to minimize secondary injury and long-term disability. Intracranial pressure, continuous electroencephalography, brain tissue oxygen, cerebral microdialysis, cerebral blood flow, and jugular oximetry monitoring have been utilized to direct treatment of the critical ill neurologic and neurosurgical patient. Optimization of monitoring technique and protocol is an ongoing effort of intensivists in the field of neurocritical care.

Detection of renal lesion enhancement with dual-energy multidetector CT.

PURPOSE: To determine whether dual-energy multidetector CT enables detection of renal lesion enhancement by using calculated nonenhanced images with spectral-based extraction in a non-body weight-restricted patient population. MATERIALS AND METHODS: Between January 2008 and December 2009, 139 patients were enrolled in this prospective HIPAA-compliant, institutional review board-approved study. Written informed consent was obtained from all patients. After single-energy nonenhanced 120-kVp CT images were acquired, contrast material-enhanced dual-energy multidetector CT images were acquired at 80 and 140 kVp. Calculated nonenhanced images were generated by using spectral-based iodine extraction. Lesion attenuation was measured on the acquired nonenhanced, calculated nonenhanced, and 140-kVp contrast-enhanced nephrographic images. Enhancement, defined as a 15-HU or greater increase in attenuation on the nephrographic images, was assessed by using the baseline attenuation on the acquired and calculated nonenhanced images. Acquired nonenhanced versus calculated nonenhanced image attenuation, as well as enhancement values, were compared by using paired Student t tests and Bland-Altman plots. RESULTS: Hypoattenuating (n = 66) and hyperattenuating (n = 28) cysts, angiomyolipomas (n = 18), and solid enhancing lesions (n = 27) were detected. Mean attenuation values for hypoattenuating cysts on the acquired and calculated nonenhanced CT images were 6.5 HU ± 5.8 (standard deviation) and 8.1 HU ± 3.1 (P = .13), respectively, with corresponding enhancement values of 1.1 HU ± 5.2 and -0.5 HU ± 6.2 (P = .12), respectively. Mean values for hyperattenuating cysts were 29.4 HU ± 5.6 on acquired images and 31.7 HU ± 5.1 on calculated images (P = .39) (corresponding enhancement, 4.7 HU ± 3.3 and 2.3 HU ± 4.1, respectively; P = .09). Mean values for fat-containing enhancing lesions were -90.6 HU ± 24.7 on acquired images and -85.9 HU ± 23.7 on calculated images (P = .57) (corresponding enhancement, 18.2 HU ± 10.1 and 13.6 HU ± 10.7, respectively; P = .19). Mean attenuation values for solid enhancing lesions were 26.0 HU ± 15.0 on acquired images and 27.7 HU ± 14.9 on calculated images (P = .45) (corresponding enhancement, 60.3 HU ± 13.1 and 58.3 HU ± 15.5, respectively; P = .38). CONCLUSION: Dual-energy CT acquisitions with spectral-based postprocessing enabled accurate detection of renal lesion enhancement across the attenuation spectrum of frequently encountered renal lesions in a non-body habitus-restricted patient population.

Effect of organ enhancement and habitus on estimation of unenhanced attenuation at contrast-enhanced dual-energy MDCT: concepts for individualized and organ-specific spectral iodine subtraction strategies.

OBJECTIVE: The purpose of this study was to assess whether habitus and organ enhancement influence iodine subtraction and should be incorporated into spectral subtraction algorithms. SUBJECTS AND METHODS: This study included 171 patients. In the unenhanced phase, MDCT was performed with single-energy acquisition (120 kVp, 250 mAs) and in the parenchymal phase with dual-energy acquisitions (80 kVp, 499 mAs; 140 kVp, 126 mAs). Habitus was determined by measuring trunk diameters and calculating circumference. Iodine subtraction was performed with input parameters individualized to muscle, fat, and blood ratio. Attenuation of the liver, pancreas, spleen, kidneys, and aorta was assessed in truly and virtually unenhanced image series. Pearson analysis was performed to correlate habitus with the input parameters. Analysis of truly unenhanced and virtually unenhanced images was performed with the Student t test; magnitude of variation was evaluated with Bland-Altman plots. Correction strategies were derived from organ-specific regression analysis of scatterplots of truly unenhanced and virtually unenhanced attenuation and implemented in a pixel-by-pixel approach. Analysis of individual organ correction and truly unenhanced attenuation was performed with the Student t test. RESULTS: The correlations between habitus and blood ratio (r = 0.694) and attenuation variation of fat at 80 kVp (r = -0.468) and 140 kV (r = -0.454) were confirmed. Although overall mean attenuation differed by no more than 10 HU between truly and virtually unenhanced scans overall, these differences varied by organ and were large in individual patients. Paired comparisons of truly and virtually unenhanced measurements differed significantly for liver, spleen, pancreas, kidneys, and aortic blood pool (p < 0.001 for all comparisons), but paired comparisons of truly unenhanced and individually organ-corrected measurements did not differ when organ- and habitus-based correction strategies were applied (p > 0.38 for all comparisons). CONCLUSION: Habitus and organ enhancement influence virtually unenhanced imaging and should be incorporated into spectral subtraction algorithms.

Prolonged transcranial Doppler monitoring after aneurysmal subarachnoid hemorrhage fails to adequately predict ischemic risk.

BACKGROUND: Stroke is common after aneurysmal subarachnoid hemorrhage (aSAH). Transcranial Doppler ultrasound (TCD) monitoring is often employed to identify vasospasm and allow intervention to avoid infarction. The required duration of monitoring has not been established. We aim to determine if 10 days of TCD monitoring identifies all patients at risk for infarction. METHODS: A 3 year retrospective analysis of aSAH patients admitted to a neurovascular center was undertaken. Eligible patients were aged 18-85 years, presenting within 2 days of hemorrhage who had underwent TCD monitoring through post bleed day 10. Patients were assessed to determine if vasospasm onset occurred after 10 days with resulting stroke. Assessment of variables potentially impacting vasospasm onset and infarction were completed. RESULTS: 107 patients met criteria with 51 (48%) demonstrating vasospasm and 31 (29%) developing stroke. Of those suffering stroke, 22 (71%) demonstrated vasospasm while 9 (22%) did not. Two (2%) patients developed vasospasm only after day 10, neither experiencing stroke. Time to vasospasm onset (5.5 ± 2.5 days) was not impacted by common radiologic or clinical scales. Glasgow Coma Scale (GCS), Hunt and Hess Score (H&H), WFNS, ventriculostomy placement, intubation, and intraventricular hemorrhage were associated with likelihood of stroke (P < 0.05). The negative predictive value of TCD for identifying stroke risk was 84% while the sensitivity was 71%. CONCLUSIONS: TCD identification of vasospasm after day 10 is rare. Stroke is more likely to result from poor detection than from brevity of TCD monitoring. Improved or alternative monitoring is needed to effectively identify ischemia and prevent stroke.

Prospective double-blinded study of abdominal-pelvic computed tomography guided by the region of tenderness: estimation of detection of acute pathology and radiation exposure reduction.

STUDY OBJECTIVE: Computed tomography (CT) is increasingly used for emergency department (ED) patients with abdominal tenderness. CT-related radiation contributes to 2% of US cancers. We hypothesized that in the ED patient with nontraumatic abdominal tenderness, the tender region accurately delineates acute pathology. z axis-restricted CT guided by this region could detect pathology while reducing radiation dose. METHODS: This was a prospective double-blinded observational trial with informed consent and was institutional review board-approved and registered with ClinicalTrials.gov. A convenience sample of ED patients undergoing abdominal CT was recruited, excluding pregnant women, patients with altered mental status or abdominal sensation, preverbal children, and patients with abdominal trauma or surgery in the previous month. Before standard CT, physicians demarcated the tender region with labels invisible to radiologists on abdominal windows. Radiologists blinded to the tender region recorded cephalad-caudad limits of pathology on CT. Personnel blinded to pathology location recorded label positions on lung windows. Two hypothetical CT strategies were then explored: CT restricted to the tender region and CT from the cephalad skin marker to the lower caudad limit of the usual CT. The percentage of the pathologic region contained within the extent of the 2 hypothetical z axis restricted CTs was calculated. z axis reduction, which is linearly related to radiation reduction, from the restricted CTs was determined. RESULTS: One hundred two subjects were enrolled, 93 with complete data for analysis. Fifty-one subjects had acute pathology on CT. CT limited to the tender region would reduce z axis (radiation exposure) by 69% (95% confidence interval [CI] 60% to 78%). All acute pathology was included within these boundaries in 17 of the 51 abnormal cases (33%; 95% CI 22% to 47%). CT from the cephalad marker through the caudad abdomen and pelvis would reduce z axis (radiation exposure) by 38% (95% CI 29% to 48%). All acute pathology was included within these boundaries in 36 of 51 abnormal cases (71%; 95% CI 57% to 81%). With both strategies 1 and 2, the pathologic region was at least partially included within the CT region in the majority of cases (84% and 92%, respectively). CONCLUSION: CT with z axis restriction based on abdominal tenderness could reduce radiation exposure but with a potentially unacceptably high rate of misdiagnosis, using our current methods. Further prospective study may be warranted to determine the diagnostic utility of partially visualized pathology.