Modeling diffusion-weighted imaging lesion expansion between 2 and 24 h after endovascular thrombectomy in acute ischemic stroke.

PURPOSE: Diffusion-weighted imaging (DWI) lesion expansion after endovascular thrombectomy (EVT) is not well characterized. We used serial diffusion-weighted magnetic resonance imaging (MRI) to measure lesion expansion between 2 and 24 h after EVT. METHODS: In this single-center observational analysis of patients with acute ischemic stroke due to large vessel occlusion, DWI was performed post-EVT (< 2 h after closure) and 24-h later. DWI lesion expansion was evaluated using multivariate generalized linear mixed modeling with various clinical moderators. RESULTS: We included 151 patients, of which 133 (88%) had DWI lesion expansion, defined as a positive change in lesion volume between 2 and 24 h. In an unadjusted analysis, median baseline DWI lesion volume immediately post-EVT was 15.0 mL (IQR: 6.6-36.8) and median DWI lesion volume 24 h post-EVT was 20.8 mL (IQR: 9.4-66.6), representing a median change of 6.1 mL (IQR: 1.5-17.7), or a 39% increase. There were no significant associations among univariable models of lesion expansion. Adjusted models of DWI lesion expansion demonstrated that relative lesion expansion (defined as final/initial DWI lesion volume) was consistent across eTICI scores (0-2a, 0.52%; 2b, 0.49%; 2c-3, 0.42%, p = 0.69). For every 1 mL increase in lesion volume, there was 2% odds of an increase in 90-day mRS (OR: 1.021, 95%CI [1.009, 1.034], p < 0.001). CONCLUSION: We observed substantial lesion expansion post-EVT whereby relative lesion expansion was consistent across eTICI categories, and greater absolute lesion expansion was associated with worse clinical outcome. Our findings suggest that alternate endpoints for cerebroprotectant trials may be feasible.

Can incorrect artificial intelligence (AI) results impact radiologists, and if so, what can we do about it? A multi-reader pilot study of lung cancer detection with chest radiography.

OBJECTIVE: To examine whether incorrect AI results impact radiologist performance, and if so, whether human factors can be optimized to reduce error. METHODS: Multi-reader design, 6 radiologists interpreted 90 identical chest radiographs (follow-up CT needed: yes/no) on four occasions (09/20-01/22). No AI result was provided for session 1. Sham AI results were provided for sessions 2-4, and AI for 12 cases were manipulated to be incorrect (8 false positives (FP), 4 false negatives (FN)) (0.87 ROC-AUC). In the Delete AI (No Box) condition, radiologists were told AI results would not be saved for the evaluation. In Keep AI (No Box) and Keep AI (Box), radiologists were told results would be saved. In Keep AI (Box), the ostensible AI program visually outlined the region of suspicion. AI results were constant between conditions. RESULTS: Relative to the No AI condition (FN = 2.7%, FP = 51.4%), FN and FPs were higher in the Keep AI (No Box) (FN = 33.0%, FP = 86.0%), Delete AI (No Box) (FN = 26.7%, FP = 80.5%), and Keep AI (Box) (FN = to 20.7%, FP = 80.5%) conditions (all ps < 0.05). FNs were higher in the Keep AI (No Box) condition (33.0%) than in the Keep AI (Box) condition (20.7%) (p = 0.04). FPs were higher in the Keep AI (No Box) (86.0%) condition than in the Delete AI (No Box) condition (80.5%) (p = 0.03). CONCLUSION: Incorrect AI causes radiologists to make incorrect follow-up decisions when they were correct without AI. This effect is mitigated when radiologists believe AI will be deleted from the patient's file or a box is provided around the region of interest. CLINICAL RELEVANCE STATEMENT: When AI is wrong, radiologists make more errors than they would have without AI. Based on human factors psychology, our manuscript provides evidence for two AI implementation strategies that reduce the deleterious effects of incorrect AI. KEY POINTS: • When AI provided incorrect results, false negative and false positive rates among the radiologists increased. • False positives decreased when AI results were deleted, versus kept, in the patient's record. • False negatives and false positives decreased when AI visually outlined the region of suspicion.

A Pilot Study of Accelerometer-Based Biometric Data Collection among Patients Undergoing Locoregional Therapies.

This study evaluated the feasibility of measuring patient recovery after locoregional therapies (LRTs) using a wearable activity tracker (WAT). Twenty adult patients with cancer were provided with a WAT device to wear for a minimum of 7 days prior to their procedure (baseline) and for up to 30 days after their procedure (recovery). Daily step counts were continuously recorded. Patient responses to the Short Form 36-Item Health Survey (SF-36) were also collected before and after LRT. Analysis of WAT data demonstrated a mean of 4,850 daily steps taken at baseline, which decreased to 2,000 immediately after LRT and then rapidly increased to approximately 4,300 daily steps over an average of 10 days (P < .001). No significant changes were observed in SF-36 responses between baseline and follow-up assessments (P > .10). These results suggest that WAT devices capture dynamic periprocedural data not reflected in survey-based assessments and may be used to monitor patient recovery after interventional oncologic procedures.

Digital Breast Tomosynthesis and Digital Mammography Recall and False-Positive Rates by Time of Day and Reader Experience.

Background Digital breast tomosynthesis (DBT) image interpretation might be more cognitively demanding than interpretation of digital mammography (DM) images. The time of day of interpretation might affect recall and false-positive (FP) rates, especially for DBT. Purpose To determine whether recall and FP rates vary by time of day of interpretation for screening mammography for breast cancer performed with DM and DBT. Materials and Methods This is a retrospective study examining 97 671 screening mammograms interpreted by 18 radiologists between January 2018 and December 2019 at one of 12 community radiology sites. The association between the time of day of interpretation, the type of image interpreted (DM vs DBT), and radiologist experience (≤5 posttraining years vs >5 posttraining years) and the likelihood of a patient being recalled from screening mammography and the likelihood of whether the interpretation was FP or true positive were analyzed. Analyses were conducted using generalized linear mixed modeling with a binary distribution and sandwich estimation where observations were nested by radiologist. Results Screening mammograms interpreted by 18 radiologists were reviewed (40 220 DBTs, 57 451 DMs). Nine radiologists had 5 or fewer posttraining years of experience, and nine had more than 5 posttraining years of experience. The overall recall rates for DM (10.2%) and DBT (9.0%) were different (P = .006); FP rate also differed (9.8% DM, 8.6% DBT; P = .004). For radiologists with 5 or fewer posttraining years of experience, odds of recall increased 11.5% (odds ratio [OR] = 1.12, P = .01) with every hour when using DBT, but this was not found for DM (OR = 1.09, P = .06); DBT and DM were different (OR = 1.12 vs 1.09, P = .02). For radiologists with more than 5 posttraining years of experience, no evidence of increase in recall was observed for DBT (OR = 1.02, P = .27) or DM (OR = 1.0, P = .80), and there was no evidence that these were different (OR = 1.02 vs 1.0, P = .13). Conclusion Patients were more likely to be recalled when their screening digital breast tomosynthesis images were interpreted later in the day by less-experienced radiologists. © RSNA, 2022 Online supplemental material is available for this article.

Comparison of MRI appendix biometrics in children with and without acute appendicitis.

OBJECTIVES: The goal of this study is to improve MRI-specific diagnostic criteria for pediatric appendicitis through comparison of normal and abnormal appendix-related imaging features. METHODS: A retrospective multireader-multicase design was used, including non-contrast MRI performed for suspected pediatric appendicitis following non-diagnostic US from January 2014 to December 2017. Positive diagnosis was defined by surgical pathology or symptom resolution after antibiotics. Four pediatric radiologists independently graded study biometrics while blinded to clinical data. Balanced complete block design was used to determine performance characteristics. RESULTS: Global diagnosis of appendicitis (208 studies) had sensitivity 90.6% and specificity 97.7%. Median appendix diameter was 10.4 mm among positive cases and 5.8 mm among negative cases (p < 0.001) with an optimal diagnostic cutoff of 7.5 mm (sensitivity 89.4%, specificity 86.5%). Median appendix wall thickness was 2.6 mm among positive cases and 1.7 mm among negative cases (p < 0.001) with an optimal diagnostic cutoff of 2.3 mm (sensitivity 63.1%, specificity 82.9%). Performance characteristics for qualitative appendix features included distinguishable appendix luminal signal (sensitivity 89.6%, specificity 83.7%), intraluminal fluid-signal intensity (sensitivity 63.6%; specificity 52.3%), intraluminal signal intermediate between fluid and bowel wall (sensitivity 91.0%; specificity 37.1%), appendicolith (sensitivity 34.9%; specificity 100.0%), intraluminal layering (sensitivity 25.9%; specificity 100.0%), hyperintense appendix wall signal (sensitivity 31.7%; specificity 100.0%), periappendiceal fluid (sensitivity 66.8%; specificity 72.5%), periappendiceal fatty edema (sensitivity 91.3%; specificity 94.5%), and free pelvic fluid (sensitivity 88.5%; specificity 26.0). CONCLUSIONS: This study provides MRI-specific performance of pediatric appendicitis quantitative and qualitative biometrics with peri-appendiceal fatty edema, appendix diameter > 7.5 mm, and distinguishable appendix luminal signal demonstrating the highest overall accuracy. KEY POINTS: • This retrospective multireader-multicase study characterized magnetic resonance imaging-specific diagnostic accuracy of quantitative and qualitative biometrics for pediatric appendicitis. • The optimal quantitative diagnostic thresholds for an abnormal pediatric appendix at MRI included diameter and wall thickness of 7.5 mm and 2.3 mm, respectively. • Qualitative imaging biometrics with high specificity for pediatric appendicitis on MRI included the presence of distinguishable appendix lumen signal from wall signal, appendicolith, intraluminal fluid-fluid layer, appendix wall hyperintensity, and peri-appendiceal fatty edema.

Adding non-contrast and delayed phases increases the diagnostic performance of arterial CTA for suspected active lower gastrointestinal bleeding.

OBJECTIVES: When assessing for lower gastrointestinal bleed (LGIB) using CTA, many advocate for acquiring non-contrast and delayed phases in addition to an arterial phase to improve diagnostic performance though the potential benefit of this approach has not been fully characterized. We evaluate diagnostic accuracy among radiologists when using single-phase, biphasic, and triphasic CTA in active LGIB detection. METHOD AND MATERIALS: A random experimental block design was used where 3 blinded radiologists specialty trained in interventional radiology retrospectively interpreted 96 CTA examinations completed between Oct 2012 and Oct 2017 using (1) arterial only, (2) arterial/non-contrast, and (3) arterial/non-contrast/delayed phase configurations. Confirmed positive and negative LGIB studies were matched, balanced, and randomly ordered. Sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, positive and negative predictive values, and time to identify the presence/absence of active bleeding were examined using generalized estimating equations (GEE) with sandwich estimation assuming a binary distribution to estimate relative benefit of diagnostic performance between phase configurations. RESULTS: Specificity increased with additional contrast phases (arterial 72.2; arterial/non-contrast 86.1; arterial/non-contrast/delayed 95.1; p < 0.001) without changes in sensitivity (arterial 77.1; arterial/non-contrast 70.2; arterial/non-contrast/delayed 73.1; p = 0.11) or mean time required to identify bleeding per study (s, arterial 34.8; arterial/non-contrast 33.1; arterial/non-contrast/delayed 36.0; p = 0.99). Overall agreement among readers (Kappa) similarly increased (arterial 0.47; arterial/non-contrast 0.65; arterial/non-contrast/delayed 0.79). CONCLUSION: The addition of non-contrast and delayed phases to arterial phase CTA increased specificity and inter-reader agreement for the detection of lower gastrointestinal bleeding without increasing reading times. KEY POINTS: • A triphasic CTA including non-contrast, arterial, and delayed phase has higher specificity for the detection of lower gastrointestinal bleeding than arterial-phase-only protocols. • Inter-reader agreement increases with additional contrast phases relative to single-phase CTA. • Increasing the number of contrast phases did not increase reading times.

Considerations in Specialty Selections: What Medical Students Think, Know, and Think They Know about Interventional Radiology.

PURPOSE: To compare the motivation, deterrents, knowledge, exposure, and other specialty considerations of first- to fourth-year medical students interested in interventional radiology (IR) with those who are not. MATERIALS AND METHODS: Matriculants of 5 medical schools varying by region, public/private, class size, and National Institutes of Health research ranking received a 19-question survey with questions about demographics, specialty interests, motivations/deterrents, knowledge, and exposure to IR. RESULTS: A total of 25.8% (611/2370) of students completed the survey, of which 20.5% (125/611) expressed interest in IR, and 25% (47/186), 26% (40/153), 24% (34/143), and 3% (3/117) of first-year, second-year, third-year, and fourth-year medical students, respectively, were seriously considering IR. Those interested in IR were less motivated by direct patient care (mean, 2.8/5; 95% confidence interval [CI], 2.6-3.0) and longitudinal patient care (mean, 1.6/5; 95% CI, 1.4-1.7) (both, P < .01) and more motivated by salary (2.6/5; 95% CI, 2.3-2.9), job market (2.8/5; 95% CI, 2.6-2.9), and procedures (3.1/5; 95% CI, 2.8-3.4) compared with their peers (all P < .05). Those interested in IR were more certain about their IR knowledge (mean range, 1.6-2.0/3.0; 95% CI, 1.3-2.3) than their peers (mean range, 1.9-2.4/3.0; 95% CI, 1.6-2.1, in which 0 = certain, P ≤ .01); however, both groups scored low in actual knowledge (those considering IR: 35.0-73.2% correct; 95% CI, 23.5-81.4; those who were not: 26.6-66.7% correct; 95% CI, 24.3-75.9, P > .05). CONCLUSIONS: Although medical students showed interest in IR, they had a limited understanding of IR. IR educators may increase IR interest and understanding among medical students by clarifying the procedural aspects and longitudinal care present in a comprehensive IR practice.

Effects of multiphase versus single-phase CT angiography for the detection of distal cerebral vessel occlusion.

PURPOSE: The goal of this study was to determine whether the benefits of multiphase CTA (mCTA) over single-phase CTA (sCTA) for the detection of proximal cerebrovascular occlusions similarly extend to the distal cerebral vasculature. METHODS: Four attending radiologists, two neuroradiologists and two emergency radiologists, contributed as readers to this retrospective study. For each reader, two sessions were conducted, one using sCTA and one using mCTA. During each session, the reader interpreted the studies of 104 patients who underwent imaging for suspicion of acute ischemic stroke, resulting in a total of 832 interpretations. Changes in diagnostic accuracy, time to render final decision, and reported levels of reader confidence were quantitatively assessed. Further analysis comparing the effects for neuroradiologists versus emergency radiologists was additionally conducted. RESULTS: Using mCTA resulted in a significant 5.0% absolute increase in sensitivity (91.6% vs. 96.6%, p = .004) and an insignificant increase in specificity (99.5% vs. 99.7%, p = .39). A significant reduction in reading time (66.7 s vs. 59.6 s, p = .001) and an increase in diagnostic confidence (2.26 vs. 2.58, p < .001) were observed. Using sCTA, higher sensitivity was achieved by neuroradiologists than emergency radiologists (96.0% vs. 86.9%, p = .002); using mCTA resulted in an absolute increase in sensitivity of 0.9% (97.4%, p = .44) for neuroradiologists and 9.6% (96.5%, p < .001) for emergency radiologists, eliminating significant differences between the groups (p = 0.57). CONCLUSION: The use of mCTA results in increased sensitivity and negative predictive value, decreased reading time, increased diagnostic confidence, and the elimination of differences in accuracy between neuroradiologists and emergency radiologists.

Digital Mammography Stereotactic Biopsy versus Digital Breast Tomosynthesis-guided Biopsy: Differences in Biopsy Targets, Pathologic Results, and Discordance Rates.

Background Digital breast tomosynthesis (DBT)-guided biopsy is increasingly used in practice. It is important to know expected changes in biopsy targets, pathologic results, and discordance rates. Purpose To compare biopsy target types, pathologic results, and discordance rates for 2 years preceding and 2 years following implementation of DBT-guided biopsy. Materials and Methods All 9-gauge vacuum-assisted core biopsies from a single tertiary breast center that used digital mammography (DM) stereotactic guidance from 2013 to 2015 and DBT-guided biopsy from 2015 to 2017 were retrospectively reviewed. All mammographic examinations were performed with DBT. Patient demographics, biopsy target type, pathologic reports, surgical excision specimens when available, breast density, and imaging follow-up results were recorded. Biopsy targets and discordance rates between radiologic and pathologic examinations were compared between the two biopsy groups. Generalized mixed modeling was used to examine results before and after DBT-guided biopsy. Results A total of 1313 women underwent 1405 breast biopsies: 643 by using DM (August 2013 to July 2015) (median age, 56 years; interquartile range, 49-66 years) and 762 by using DBT (August 2015 to July 2017) (median age, 58 years; interquartile range, 50-67 years), (P = .58). Calcifications were the most common biopsy target for both groups, constituting 89.9% (578 of 643) of DM-guided biopsies and 71.1% (542 of 762) of DBT-guided biopsies (P = .03). The rate of architectural distortion biopsies was 2.0% (13 of 643) with DM-guided biopsy and 17.7% (135 of 762) with DBT-guided biopsy (P = .01). Although overall malignancy rate was similar for DM-guided biopsy (27.8% [179 of 643]) and DBT-guided biopsy (24.8% [191 of 762], P = .54), DBT-guided biopsy helped identify a similar percentage of invasive malignancies (37.4% [72 of 191] vs 29.0% [52 of 179] at DM P = .35), but more radial sclerosing lesions (8.3% [95% confidence interval {CI}: 6.0, 10.0] vs 1.7% [95% CI: 1.0, 3.1]) (P = .01). The discordance rate was 1.4% (95% CI: 1.0, 2.7) with DM-guided biopsy and 4.5% (95% CI: 3.2, 6.3) with DBT-guided biopsy (P = .01). Of the 34 discordant DBT-guided biopsies, 30 were architectural distortions. Conclusion With the transition to digital breast tomosynthesis-guided biopsy, more architectural distortions were biopsied, more radial sclerosing lesions were identified, and more discordance existed in radiologic and pathologic examinations, with a similar percentage of carcinomas diagnosed. © RSNA, 2020 Online supplemental material is available for this article.

Detecting Large Vessel Occlusion at Multiphase CT Angiography by Using a Deep Convolutional Neural Network.

Background Large vessel occlusion (LVO) stroke is one of the most time-sensitive diagnoses in medicine and requires emergent endovascular therapy to reduce morbidity and mortality. Leveraging recent advances in deep learning may facilitate rapid detection and reduce time to treatment. Purpose To develop a convolutional neural network to detect LVOs at multiphase CT angiography. Materials and Methods This multicenter retrospective study evaluated 540 adults with CT angiography examinations for suspected acute ischemic stroke from February 2017 to June 2018. Examinations positive for LVO (n = 270) were confirmed by catheter angiography and LVO-negative examinations (n = 270) were confirmed through review of clinical and radiology reports. Preprocessing of the CT angiography examinations included vasculature segmentation and the creation of maximum intensity projection images to emphasize the contrast agent-enhanced vasculature. Seven experiments were performed by using combinations of the three phases (arterial, phase 1; peak venous, phase 2; and late venous, phase 3) of the CT angiography. Model performance was evaluated on the held-out test set. Metrics included area under the receiver operating characteristic curve (AUC), sensitivity, and specificity. Results The test set included 62 patients (mean age, 69.5 years; 48% women). Single-phase CT angiography achieved an AUC of 0.74 (95% confidence interval [CI]: 0.63, 0.85) with sensitivity of 77% (24 of 31; 95% CI: 59%, 89%) and specificity of 71% (22 of 31; 95% CI: 53%, 84%). Phases 1, 2, and 3 together achieved an AUC of 0.89 (95% CI: 0.81, 0.96), sensitivity of 100% (31 of 31; 95% CI: 99%, 100%), and specificity of 77% (24 of 31; 95% CI: 59%, 89%), a statistically significant improvement relative to single-phase CT angiography (P = .01). Likewise, phases 1 and 3 and phases 2 and 3 also demonstrated improved fit relative to single phase (P = .03). Conclusion This deep learning model was able to detect the presence of large vessel occlusion and its diagnostic performance was enhanced by using delayed phases at multiphase CT angiography examinations. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Ospel and Goyal in this issue.

Treatment of psychogenic nonepileptic seizures (PNES) using video telehealth.

OBJECTIVE: Previous studies have shown the effectiveness of manual-based treatment for psychogenic nonepileptic seizures (PNES), but access to mental health care still remains a problem, especially for patients living in areas without medical professionals who treat conversion disorder. Thus, we evaluated patients treated with cognitive behavioral therapy-informed psychotherapy for seizures with clinical video telehealth (CVT). We evaluated neuropsychiatric and seizure treatment outcomes in veterans diagnosed with PNES seen remotely via telehealth. We hypothesized that seizures and comorbidities will improve with treatment. METHODS: This was a single-arm, prospective, observational, cohort, consecutive outpatient study. Patients with video-electroencephalography-confirmed PNES (n = 32) documented their seizure counts daily and comorbid symptoms prospectively over the course of treatment. Treatment was provided using a 12-session manual-based psychotherapy treatment given once per week, via CVT with a clinician at the Providence Veterans Affairs Medical Center. RESULTS: The primary outcome, seizure reduction, was 46% (P = .0001) per month over the course of treatment. Patients also showed significant improvements in global functioning (Global Assessment of Functioning, P = < .0001), quality of life (Quality of Life in Epilepsy Inventory-31, P = .0088), and health status scales (Short Form 36 Health Survey, P < .05), and reductions in both depression (Beck Depression Inventory-II, P = .0028) and anxiety (Beck Anxiety Inventory, P = .0013) scores. SIGNIFICANCE: Patients with PNES treated remotely with manual-based seizure therapy decreased seizure frequency and comorbid symptoms and improved functioning using telehealth. These results suggest that psychotherapy via telehealth for PNES is a viable option for patients across the nation, eliminating one of the many barriers of access to mental health care.

Detection of emergent large vessel occlusion stroke with CT angiography is high across all levels of radiology training and grayscale viewing methods.

OBJECTIVES: CT angiography (CTA) is essential in acute stroke to detect emergent large vessel occlusions (ELVO) and must be interpreted by radiologists with and without subspecialized training. Additionally, grayscale inversion has been suggested to improve diagnostic accuracy in other radiology applications. This study examines diagnostic performance in ELVO detection between neuroradiologists, non-neuroradiologists, and radiology residents using standard and grayscale inversion viewing methods. METHODS: A random, counterbalanced experimental design was used, where 18 radiologists with varying experiences interpreted the same patient images with and without grayscale inversion. Confirmed positive and negative ELVO cases were randomly ordered using a balanced design. Sensitivity, specificity, positive and negative predictive values as well as confidence, subjective assessment of image quality, time to ELVO detection, and overall interpretation time were examined between grayscale inversion (on/off) by experience level using generalized mixed modeling assuming a binary, negative binomial, and binomial distributions, respectively. RESULTS: All groups of radiologists had high sensitivity and specificity for ELVO detection (all > .94). Neuroradiologists were faster than non-neuroradiologists and residents in interpretation time, with a mean of 47 s to detect ELVO, as compared with 59 and 74 s, respectively. Residents were subjectively less confident than attending physicians. With respect to grayscale inversion, no differences were observed between groups with grayscale inversion vs. standard viewing for diagnostic performance (p = 0.30), detection time (p = .45), overall interpretation time (p = .97), and confidence (p = .20). CONCLUSIONS: Diagnostic performance in ELVO detection with CTA was high across all levels of radiologist training level. Grayscale inversion offered no significant detection advantage. KEY POINTS: • Stroke is an acute vascular syndrome that requires acute vascular imaging. • Proximal large vessel occlusions can be identified quickly and accurately by radiologists across all training levels. • Grayscale inversion demonstrated minimal detectable benefit in the detection of proximal large vessel occlusions.

CT Densitometry and Morphology of Radiofrequency-Ablated Stage IA Non-Small Cell Lung Cancer: Results from the American College of Surgeons Oncology Group Z4033 (Alliance) Trial.

PURPOSE: To evaluate tumor and ablation zone morphology and densitometry related to tumor recurrence in participants with Stage IA non-small cell lung cancer undergoing radiofrequency ablation in a prospective, multicenter trial. MATERIALS AND METHODS: Forty-five participants (median 76 years old; 25 women; 20 men) from 16 sites were followed for 2 years (December 2006 to November 2010) with computed tomography (CT) densitometry. Imaging findings before and after ablation were recorded, including maximum CT attenuation (in Hounsfield units) at precontrast and 45-, 90-, 180-, and 300-s postcontrast. RESULTS: Every 1-cm increase in the largest axial diameter of the ablation zone at 3-months' follow-up compared to the index tumor reduced the odds of 2-year recurrence by 52% (P = .02). A 1-cm difference performed the best (sensitivity, 0.56; specificity, 0.93; positive likelihood ratio of 8). CT densitometry precontrast and at 45 seconds showed significantly different enhancement patterns in a comparison among pretreated lung cancer (delta = +61.2 HU), tumor recurrence (delta = +57 HU), and treated tumor/ablation zone (delta [change in attenuation] = +16.9 HU), (P < .0001). Densitometry from 45 to 300 s was also different among pretreated tumor (delta = -6.8 HU), recurrence (delta = -11.2 HU), and treated tumor (delta = +12.1 HU; P = .01). Untreated and residual tumor demonstrated washout, whereas treated tumor demonstrated increased attenuation. CONCLUSIONS: An ablation zone ≥1 cm larger than the initial tumor, based on 3-month follow-up imaging, is recommended to decrease odds of recurrence. CT densitometry can delineate tumor versus treatment zones.

Adjuvant Thermal Accelerant Gel Use Increases Microwave Ablation Zone Temperature in Porcine Liver as Measured by MR Thermometry.

PURPOSE: To determine the effects of a thermal accelerant gel on temperature parameters during microwave liver ablation. MATERIALS AND METHODS: Sixteen consecutive liver ablations were performed in 5 domestic swine under general anesthesia with (n = 8) and without (n = 8) administration of thermal accelerant gel. Ablation zone temperature was assessed by real-time MR thermometry, measured as maximum temperature (Tmax) and the volume of tissue ≥ 60°C (V60). Tissue heating rate, ablation zone shape, and thermal energy deposition using the temperature degree-minutes at 43°C (TDM43) index were also measured. Differences between groups were analyzed using generalized mixed modeling with significance set at P = .05. RESULTS: Mean peak ablation zone temperature was significantly greater with thermal accelerant use (mean Tmax, thermal accelerant: 120.0°C, 95% confidence interval [CI] 113.0°C-126.9°C; mean Tmax, control: 80.3°C, 95% CI 72.7°C-88.0°C; P < .001), and a significantly larger volume of liver tissue achieved or exceeded 60°C when thermal accelerant was administered (mean V60, thermal accelerant: 22.2 cm3; mean V60, control: 15.9 cm3; P < .001). Significantly greater thermal energy deposition was observed during ablations performed with accelerant (mean TDM43, thermal accelerant: 198.4 min, 95% CI 170.7-230.6 min; mean TDM43, control: 82.8 min, 95% CI 80.5-85.1 min; P < .0001). The rate of tissue heating was significantly greater with thermal accelerant use (thermal accelerant: 5.8 min ± 0.4; control: 10.0 min; P < .001), and accelerant gel ablations demonstrated a more spherical temperature distribution (P = .002). CONCLUSIONS: Thermal accelerant use is associated with higher microwave ablation zone temperatures, greater thermal energy deposition, and faster and more spherical tissue heating compared with control ablations.

The growing issue of burnout in radiology - a survey-based evaluation of driving factors and potential impacts in pediatric radiologists.

BACKGROUND: Burnout in medicine, and specifically radiology, has been receiving more attention. Little data-driven literature is available regarding risk factors/causes to ultimately help guide the development of potential solutions. OBJECTIVE: To survey pediatric radiologists, a cohort with a documented high prevalence of burnout, and to understand the impact of clinical demands on nonclinical tasks and the implications of burnout on mental health. MATERIALS AND METHODS: A survey of Society for Pediatric Radiology (SPR) North America attendings was performed regarding institutional factors contributing to burnout, including call burden, clinical demands, departmental support and administrative/academic tasks. Questions regarding mental health and wellness resources were also included. Generalized linear modeling assuming binomial distribution was used for analyses with SAS 9.4. RESULTS: The response rate was 305/1,282 (24%) with 53% of respondents female. Respondents reported that both the number and complexity of clinical cases have increased since they first started practice as an attending, while the time for interpretation has not changed, P<0.0001. Using a scale of 0 (never), 1 (rarely), 2 (sometimes), 3 (frequently) and 4 (always), covering multiple hospitals (2.2) and administrative tasks (2.4) were the most stressful job factors. For those in administrative roles, the most stressful job factors were job-related tasks affected teaching duties (2.0) and decreased overall job satisfaction (2.0). Of the respondents, 52% said they know a physician affected by work stress-related mental illness and 25% know a physician who has contemplated or committed suicide. While 39% of the respondents have resources available to address burnout, only 33% utilize these resources. CONCLUSION: Increasing clinical demands and additional institutional/departmental factors play a potential role in burnout, which has serious implications for the mental health of pediatric radiologists.

Readability of Online Patient Educational Materials Related to Breast Lesions Requiring Surgery.

Purpose To evaluate readability of websites that are commonly accessed for information on breast lesions requiring surgery. Materials and Methods An internet search using three malignant and eight nonmalignant breast lesions that traditionally require lumpectomy or excisional biopsy as search terms was conducted to identify websites commonly accessed for patient information on breast lesions requiring surgery. Nine websites with information on breast diagnoses were identified based on search engine results for each breast lesion queried. Available patient-directed information was downloaded for each lesion from each website on May 15, 2018. Grade-level readability of downloaded content for each lesion was then determined by using generalized estimating equations, with observations nested within readability metrics from each website. Readability of associated terms breast biopsy, breast cancer, and breast surgery was also evaluated with the same method. Results were compared with American Medical Association (AMA) recommended readability parameters (sixth-grade reading level). All interval estimates were calculated for 95% confidence. Results Average grade level readability score of health information on breast lesions requiring surgery was 11.7, which exceeded the AMA parameters. Information on Wikipedia was written at the highest reading level (grade level readability score, 14.2), while information on the National Institutes of Health website ( http://cancer.gov ) was written at the lowest reading level (grade level readability score, 9.7). Educational materials on malignant breast lesions (grade level readability score, 12.3) were written at a higher reading level than were those on nonmalignant breast lesions (grade level readability score,11.4). Information on the terms breast biopsy (grade level readability score, 10.9), breast cancer (grade level readability score, 10.6), and breast surgery (grade level readability score, 11.1) were all written above a sixth-grade reading level. Conclusion Readability of current online resources on breast biopsy lesions traditionally requiring surgery may be too complex for the general public to comprehend, leading to misinformation and confusion. © RSNA, 2019 See also the editorial by Haygood in this issue.

Effects of a Thermal Accelerant Gel on Microwave Ablation Zone Volumes in Lung: A Porcine Study.

Background Thermal ablation of cancers may be associated with high rates of local tumor progression. A thermal accelerant gel has been developed to improve the transmission of microwave energy in biologic tissues with the aim of enlarging the thermal ablation zone. Purpose To determine the effects of a thermal accelerant gel on microwave ablation zone volumes in porcine lung and to compare percutaneous and endobronchial delivery methods. Materials and Methods Thirty-two consecutive microwave lung ablations were performed in nine 12-week-old domestic male swine under general anesthesia by using fluoroscopic guidance between September 2017 and April 2018. Experimental ablations were performed following percutaneous injection of thermal accelerant into the lung (n = 16) or after endobronchial injection by using a flexible bronchoscope (n = 8). Control ablations were performed without accelerant gel (n = 8). Lung tissue was explanted after the animals were killed, and ablation zone volumes were calculated as the primary outcome measure by using triphenyltetrazolium chloride vital staining. Differences in treatment volumes were analyzed by generalized mixed modeling. Results Thermal accelerant ablation zone volumes were larger than control ablations (accelerant vs control ablation, 4.3 cm3 [95% confidence interval: 3.4, 5.5] vs 2.1 cm3 [95% confidence interval: 1.4, 2.9], respectively; P < .001). Among ablations with the thermal accelerant, those performed following percutaneous injection had a larger average ablation zone volume than those performed following endobronchial injection (percutaneous vs endobronchial, 4.8 cm3 [95% confidence interval: 3.6, 6.4] vs 3.3 cm3 [95% confidence interval: 2.9, 3.8], respectively; P = .03). Ablation zones created after endobronchial gel injection were more uniform in size distribution (standard error, percutaneous vs endobronchial: 0.13 vs 0.07, respectively; P = .03). Conclusion Use of thermal accelerant results in larger microwave ablation zone volumes in normal porcine lung tissue. Percutaneous thermal accelerant injection leads to a larger ablation zone volume compared with endobronchial injection, whereas a more homogeneous and precise ablation zone size is observed by using the endobronchial approach. © RSNA, 2019 See also the editorial by Goldberg in this issue.

A single-center analysis of early readmission after renal transplantation.

BACKGROUND: Thirty-day readmission rates (early hospital readmission, EHR) are an important benchmark for quality improvement. Nationally, patients undergoing renal transplantation incur a 31% EHR rate. While national databases provide useful data, the impact of EHR on individual centers has received little attention. We proposed that an institutional review of EHR after renal transplantation may provide a benchmark for individual transplant programs and identify modifiable program-specific issues to reduce EHR. METHODS: We reviewed 269 consecutive kidney transplant recipients over a five-year period (2012-2016). Early hospital readmission was modeled using generalized linear modeling assuming a binary distribution. RESULTS: About 21% of patients were readmitted within 30 days. Deceased kidney donation (DD), delayed graft functioning (DGF), anti-thymocyte globulin (ATG) induction, diabetes, public insurance, weekend discharge, and low glomerular filtration rate (eGFR) at discharge were all identified as risk factors for readmission. Early hospital readmission was not correlated with risk of death (5.4% at 44 months: HR 2.2 (95% CI [0.7, 6.6]; P = 0.1473) or graft loss. CONCLUSIONS: EHR after renal transplantation is common. Certain factors may predict an increased risk for EHR. A multi-disciplinary approach to discharge planning may limit some EHR, but most complications and adverse events are unpredictable and require hospital-level of care.

FDG PET/CT of Infection: Should It Replace Labeled Leukocyte Scintigraphy of Inpatients?

OBJECTIVE. The purpose of this study was to compare the sensitivity, specificity, and helpfulness to referring clinicians of labeled leukocyte scintigraphy versus FDG PET/CT in inpatients with suspected infection. MATERIALS AND METHODS. In this retrospective study, labeled leukocyte scintigraphy and FDG PET/CT examinations performed from 2009 to 2017 for suspected infection in inpatients were identified. Sensitivity, specificity, and helpfulness of PET/CT versus labeled leukocyte scintigraphy were calculated by means of a mixed generalized linear model. Number of yearly tests and radiopharmaceutical costs were also assessed. RESULTS. Fifty-seven patients (30 men, 27 women; median age, 65 years; range, 21-91 years) underwent whole-body labeled leukocyte scintigraphy. Forty-two patients (30 male patients, 12 female patients; median age, 62.5 years; range, 12-91 years) underwent PET/CT for suspected infection. Labeled leukocyte scintigraphy was 66.7% sensitive, whereas the sensitivity of PET/CT was 89.7% (p = 0.0485). The higher sensitivity of PET/CT did not come at a cost to specificity, which was 73.3% as opposed to 76.9% for labeled leukocyte scintigraphy (p = 0.8050). The odds of a positive study being helpful increased 4.6-fold for PET/CT versus labeled leukocyte scintigraphy (p = 0.0412). From 2009 to 2011, 33 labeled leukocyte scintigraphic examinations were performed versus two PET/CT examinations; and from 2012 to 2014, 16 labeled leukocyte scintigraphic versus 22 PET/CT examinations; from 2015 to 2017, eight labeled leukocyte scintigraphic versus 18 PET/CT examinations. The cost of labeled leukocytes increased between 2009 and 2017, but that of FDG decreased. By 2017, a labeled leukocyte radiopharmaceutical dose was approximately 10 times the cost of an FDG dose. CONCLUSION. PET/CT was more sensitive than and as specific as labeled leukocyte scintigraphy for identifying a source of infection in inpatients, and it was more helpful to referring clinicians. Use of PET/CT increased over time and was associated with substantial savings in radiopharmaceutical cost.

Dense Breast Ultrasound Screening After Digital Mammography Versus After Digital Breast Tomosynthesis.

OBJECTIVE. The objective of this study was to compare the yield of dense breast ultrasound (US) screening after digital mammography (DM) versus after digital breast tomosyn-thesis (DBT). MATERIALS AND METHODS. For this institutional review board-approved, HIPAA-compliant study, we retrospectively searched databases at two tertiary breast imaging centers and an office practice staffed by the same fellowship-trained breast radiologists for screening US examinations from October 1, 2014, to September 30, 2016. Prior DM versus DBT and screening US and pathology results were recorded. Mammographically occult cancers detected with US and additional benign lesions requiring biopsy were calculated. Differences between DM and DBT were compared using the two-sample proportions z test. RESULTS. A total of 3183 screening breast US examinations were performed, 1434 (45.1%) after DM and 1668 (52.4%) after DBT. Of the 3183 examinations, 81 (2.5%) had no prior mammogram available. Of the 122 DM and DBT patients for whom biopsy or cyst aspiration was recommended (all BI-RADS assessment category 4 or BI-RADS assessment category 5 studies), 118 (96.7%) had biopsy or cyst aspiration results available. Of the 36 biopsies or aspirations after DM, 6 (16.7%) were malignant and 30 (83.3%) were benign; of the 82 biopsies or aspirations after DBT, 11 (13.4%) were malignant and 71 (86.6%) were benign (p = 0.8583). The additional cancer detection rate by US after DM was 5/1434 or 3.5 per 1000 women screened and after DBT was 5/1668 or 3.0 per 1000 women screened (p = 0.9999). CONCLUSION. No significant difference in additional cancer detection rate was found with screening US after DM versus after DBT.