Effects of Low-Level Light Therapy on Resting-State Connectivity Following Moderate Traumatic Brain Injury: Secondary Analyses of a Double-blinded Placebo-controlled Study.

Background Low-level light therapy (LLLT) has been shown to modulate recovery in patients with traumatic brain injury (TBI). However, the impact of LLLT on the functional connectivity of the brain when at rest has not been well studied. Purpose To use functional MRI to assess the effect of LLLT on whole-brain resting-state functional connectivity (RSFC) in patients with moderate TBI at acute (within 1 week), subacute (2-3 weeks), and late-subacute (3 months) recovery phases. Materials and Methods This is a secondary analysis of a prospective single-site double-blinded sham-controlled study conducted in patients presenting to the emergency department with moderate TBI from November 2015 to July 2019. Participants were randomized for LLLT and sham treatment. The primary outcome of the study was to assess structural connectivity, and RSFC was collected as the secondary outcome. MRI was used to measure RSFC in 82 brain regions in participants during the three recovery phases. Healthy individuals who did not receive treatment were imaged at a single time point to provide control values. The Pearson correlation coefficient was estimated to assess the connectivity strength for each brain region pair, and estimates of the differences in Fisher z-transformed correlation coefficients (hereafter, z differences) were compared between recovery phases and treatment groups using a linear mixed-effects regression model. These analyses were repeated for all brain region pairs. False discovery rate (FDR)-adjusted P values were computed to account for multiple comparisons. Quantile mixed-effects models were constructed to quantify the association between the Rivermead Postconcussion Symptoms Questionnaire (RPQ) score, recovery phase, and treatment group. Results RSFC was evaluated in 17 LLLT-treated participants (median age, 50 years [IQR, 25-67 years]; nine female), 21 sham-treated participants (median age, 50 years [IQR, 43-59 years]; 11 female), and 23 healthy control participants (median age, 42 years [IQR, 32-54 years]; 13 male). Seven brain region pairs exhibited a greater change in connectivity in LLLT-treated participants than in sham-treated participants between the acute and subacute phases (range of z differences, 0.37 [95% CI: 0.20, 0.53] to 0.45 [95% CI: 0.24, 0.67]; FDR-adjusted P value range, .010-.047). Thirteen different brain region pairs showed an increase in connectivity in sham-treated participants between the subacute and late-subacute phases (range of z differences, 0.17 [95% CI: 0.09, 0.25] to 0.26 [95% CI: 0.14, 0.39]; FDR-adjusted P value range, .020-.047). There was no evidence of a difference in clinical outcomes between LLLT-treated and sham-treated participants (range of differences in medians, -3.54 [95% CI: -12.65, 5.57] to -0.59 [95% CI: -7.31, 8.49]; P value range, .44-.99), as measured according to RPQ scores. Conclusion Despite the small sample size, the change in RSFC from the acute to subacute phases of recovery was greater in LLLT-treated than sham-treated participants, suggesting that acute-phase LLLT may have an impact on resting-state neuronal circuits in the early recovery phase of moderate TBI. ClinicalTrials.gov Identifier: NCT02233413 © RSNA, 2024 Supplemental material is available for this article.

Percent Insular Ribbon Infarction for Predicting Infarct Growth Rate and 90-Day Outcomes in Large-Vessel Occlusive Stroke: Secondary Analysis of Prospective Clinical Trial Data.

BACKGROUND. Insight into the natural history of infarct growth could help identify patients with slowly progressing stroke who may benefit from delayed endovascular thrombectomy (EVT). OBJECTIVE. The purpose of this article is to evaluate associations of percent insular ribbon infarction (PIRI) with infarct growth rate (IGR) and 90-day outcomes in patients with large-vessel occlusive stroke. METHODS. This retrospective study was a secondary analysis of a prior clinical trial that enrolled patients with acute stroke not treated with reperfusion therapies from January 2007 to June 2009. The present analysis evaluated 31 trial patients (median age, 71 years; 12 women, 19 men) with anterior-circulation large-vessel occlusion who underwent serial MRI examinations. Two neuroradiologists independently scored PIRI on presentation MRI examinations on the basis of the ratio of the length of the portion of the insula showing restricted diffusion to the insula's total length using a previously described 0-4 scale; scores were categorized (mild [0-1], moderate [2], or severe [3-4]), and discrepancies were resolved by consensus. The 90-day modified Rankin Scale (mRS) was obtained. As part of earlier clinical trial analyses, collateral pattern on CTA was classified as symmetric, malignant, or other, and infarct volumes were measured on DWI during the initial 48 hours after presentation and on FLAIR at 90 days. RESULTS. Interrater agreement for PIRI category was strong (κ = 0.89). PIRI was mild in 10, moderate in four, and severe in 17 patients. For mild, moderate, and severe PIRI, median IGR from onset to presentation was 1.6 cm3/h, 8.5 cm3/h, and 17.5 cm3/h (p < .001); median IGR from presentation to 48 hours was 0.3 cm3/h, 0.2 cm3/h, and 1.2 cm3/h (p = .005); median 90-day infarct volume was 9.4 cm3, 39.8 cm3, and 108.6 cm3 (p = .01); and 90-day mRS of 2 or less occurred in 78%, 67%, and 6% of patients (p = .001). In multivariable models controlling for age, internal carotid artery occlusion, and collateral pattern, PIRI category independently predicted onset-to-presentation IGR (ß = 1.5), presentation-to-48-hour IGR (ß = 1.3), and 90-day mRS of 2 or less (OR = 0.2). For predicting 90-day mRS of 2 or less, mild-to-moderate PIRI had sensitivity of 90.0% and specificity of 84.2%; symmetric collateral pattern had sensitivity of 70.0% and specificity of 73.7%. CONCLUSION. PIRI was independently associated with IGR and 90-day outcome. CLINICAL IMPACT. PIRI may help identify patients who could benefit from late-window EVT when requiring transfer to EVT-capable centers.

Longitudinal Imaging in a Patient With Opioid-associated Amnestic Syndrome.

Since 2012, individuals with a history of opioid misuse have infrequently been observed to develop a sudden-onset amnestic syndrome associated with bilateral hippocampal-restricted diffusion on MRI. Follow-up imaging of this opioid-associated amnestic syndrome (OAS) has revealed persistent hippocampal abnormalities. Given these observations, as well as neuropathological studies demonstrating excessive tau deposition in the hippocampi and other brain regions of individuals with opioid misuse, we describe longitudinal imaging of a patient with a history of OAS from presentation through 53 months later, when tau positron emission tomography (PET) was performed. Our patient was a 21-year-old woman with a history of attention-deficit hyperactivity disorder and substance use disorder, including opioids (intravenous heroin), who was hospitalized for acute-onset, dense anterograde amnesia. Her urine toxicology screen was positive for opiates. On presentation, her brain MRI showed restricted diffusion as well as T2 and fluid-attenuated inversion recovery (FLAIR) hyperintensity of the hippocampi and globi pallidi. On day 3, magnetic resonance spectroscopy of a right hippocampal region of interest showed a mild reduction of N-acetyl aspartate/creatine, slight elevation of choline/creatine, and the appearance of lactate/lipid and glutamate/glutamine peaks. At 4.5 months, there was resolution of restricted diffusion on MRI, although a minimal anterior T2 and FLAIR hyperintense signal in the right hippocampus persisted. However, by 53 months, when mild memory loss was reported, the hippocampi appeared normal on MRI, and [ 18 F]T807 (tau) PET showed no uptake suggestive of tau deposition. This case report supports the investigation into the hypothesis that OAS may follow a trajectory of reversible metabolic injury.

Aluminum Thin Film Nanostructure Traces in Pediatric EEG Net for MRI and CT Artifact Reduction.

Magnetic resonance imaging (MRI) and continuous electroencephalogram (EEG) monitoring are essential in the clinical management of neonatal seizures. EEG electrodes, however, can significantly degrade the image quality of both MRI and CT due to substantial metallic artifacts and distortions. Thus, we developed a novel thin film trace EEG net ("NeoNet") for improved MRI and CT image quality without compromising the EEG signal quality. The aluminum thin film traces were fabricated with an ultra-high-aspect ratio (up to 17,000:1, with dimensions 30 nm × 50.8 cm × 100 µm), resulting in a low density for reducing CT artifacts and a low conductivity for reducing MRI artifacts. We also used numerical simulation to investigate the effects of EEG nets on the B1 transmit field distortion in 3 T MRI. Specifically, the simulations predicted a 65% and 138% B1 transmit field distortion higher for the commercially available copper-based EEG net ("CuNet", with and without current limiting resistors, respectively) than with NeoNet. Additionally, two board-certified neuroradiologists, blinded to the presence or absence of NeoNet, compared the image quality of MRI images obtained in an adult and two children with and without the NeoNet device and found no significant difference in the degree of artifact or image distortion. Additionally, the use of NeoNet did not cause either: (i) CT scan artifacts or (ii) impact the quality of EEG recording. Finally, MRI safety testing confirmed a maximum temperature rise associated with the NeoNet device in a child head-phantom to be 0.84 °C after 30 min of high-power scanning, which is within the acceptance criteria for the temperature for 1 h of normal operating mode scanning as per the FDA guidelines. Therefore, the proposed NeoNet device has the potential to allow for concurrent EEG acquisition and MRI or CT scanning without significant image artifacts, facilitating clinical care and EEG/fMRI pediatric research.

Symmetric CTA Collaterals Identify Patients with Slow-progressing Stroke Likely to Benefit from Late Thrombectomy.

Background Understanding ischemic core growth rate (IGR) is key in identifying patients with slow-progressing large vessel occlusion (LVO) stroke who may benefit from delayed endovascular thrombectomy (EVT). Purpose To evaluate whether symmetric collateral pattern at CT angiography (CTA) can help to identify patients with low IGR and small 24-hour diffusion-weighted MRI ischemic core volume in patients with LVO not treated with reperfusion therapies. Materials and Methods In this secondary analysis of clinical trial data from before EVT became standard of care from January 2007 to June 2009, patients with anterior proximal LVO not treated with reperfusion therapies were evaluated. All patients underwent admission CTA and at least three MRI examinations at four time points over 48 hours. Arterial phase CTA collaterals at presentation were categorized as symmetric, malignant, or other. Diffusion-weighted MRI ischemic core volume and IGR at multiple time points were determined. The IGR at presentation was defined as follows: (ischemic core volume in cubic centimeters)/(time since stroke symptom onset in hours). Multivariable analyses and receiver operator characteristic analyses were used. Results This study evaluated 31 patients (median age, 71 years; interquartile range, 61-81 years; 19 men) with median National Institutes of Health Stroke Scale (NIHSS) score of 13. Collaterals were symmetric (45%; 14 of 31), malignant (13%; four of 31), or other (42%; 13 of 31). Median ischemic core volume was different between collateral patterns at all time points. Presentation was as follows: symmetric, 16 cm3; other, 69 cm3; and malignant, 104 cm3 (P < .001). At 24 hours, median ischemic core volumes were as follows: symmetric, 28 cm3; other, 156 cm3; and malignant, 176 cm3 (P < .001). Median IGR was also different, and most pronounced at presentation: symmetric, 4 cm3 per hour; other, 17 cm3 per hour; and malignant, 20 cm3 per hour (P < .001). After multivariable adjustment, independent determinants of higher presentation IGR included only higher NIHSS (parameter estimate [ß = 0.20; 95% CI: 0.05, 0.36; P = .008) and worse collaterals (ß = -2.90; 95% CI: -4.31, -1.50; P < .001). The only independent determinant of 24-hour IGR was worse collaterals (ß = -2.03; 95% CI: -3.28, -0.78; P = .001). Symmetric collaterals had sensitivity of 87% (13 of 15) and specificity of 94% (15 of 16) for 24-hour ischemic core volume less than 50 cm3 (area under the receiver operating characteristic curve, 0.92; 95% CI: 0.81, 1.00; P < .001). Conclusion In patients with large vessel occlusion not treated with reperfusion therapies, symmetric collateral pattern at CT angiography was common and highly specific for low ischemic core growth rate and small 24-hour ischemic core volume as assessed at diffusion-weighted MRI. After further outcome studies, collateral status at presentation may prove useful in triage for endovascular thrombectomy, especially when MRI and CT perfusion are unavailable. Clinical trial registration no. NCT00414726. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Messina in this issue.

Optimization of magnetization transfer contrast for EPI FLAIR brain imaging.

PURPOSE: To evaluate the impact of magnetization transfer (MT) on brain tissue contrast in turbo-spin-echo (TSE) and EPI fluid-attenuated inversion recovery (FLAIR) images, and to optimize an MT-prepared EPI FLAIR pulse sequence to match the tissue contrast of a clinical reference TSE FLAIR protocol. METHODS: Five healthy volunteers underwent 3T brain MRI, including single slice TSE FLAIR, multi-slice TSE FLAIR, EPI FLAIR without MT-preparation, and MT-prepared EPI FLAIR with variations of the MT-preparation parameters, including number of preparation pulses, pulse amplitude, and resonance offset. Automated co-registration and gray matter (GM) versus white matter (WM) segmentation was performed using a T1-MPRAGE acquisition, and the GM versus WM signal intensity ratio (contrast ratio) was calculated for each FLAIR acquisition. RESULTS: Without MT preparation, EPI FLAIR showed poor tissue contrast (contrast ratio = 0.98), as did single slice TSE FLAIR. Multi-slice TSE FLAIR provided high tissue contrast (contrast ratio = 1.14). MT-prepared EPI FLAIR closely approximated the contrast of the multi-slice TSE FLAIR images for two combinations of the MT-preparation parameters (contrast ratio = 1.14). Optimized MT-prepared EPI FLAIR provided a 50% reduction in scan time compared to the reference TSE FLAIR acquisition. CONCLUSION: Optimized MT-prepared EPI FLAIR provides comparable brain tissue contrast to the multi-slice TSE FLAIR images used in clinical practice.

An artificial intelligence-accelerated 2-minute multi-shot echo planar imaging protocol for comprehensive high-quality clinical brain imaging.

PURPOSE: We introduce and validate an artificial intelligence (AI)-accelerated multi-shot echo-planar imaging (msEPI)-based method that provides T1w, T2w, T2∗ , T2-FLAIR, and DWI images with high SNR, high tissue contrast, low specific absorption rates (SAR), and minimal distortion in 2 minutes. METHODS: The rapid imaging technique combines a novel machine learning (ML) scheme to limit g-factor noise amplification and improve SNR, a magnetization transfer preparation module to provide clinically desirable contrast, and high per-shot EPI undersampling factors to reduce distortion. The ML training and image reconstruction incorporates a tunable parameter for controlling the level of denoising/smoothness. The performance of the reconstruction method is evaluated across various acceleration factors, contrasts, and SNR conditions. The 2-minute protocol is directly compared to a 10-minute clinical reference protocol through deployment in a clinical setting, where five representative cases with pathology are examined. RESULTS: Optimization of custom msEPI sequences and protocols was performed to balance acquisition efficiency and image quality compared to the five-fold longer clinical reference. Training data from 16 healthy subjects across multiple contrasts and orientations were used to produce ML networks at various acceleration levels. The flexibility of the ML reconstruction was demonstrated across SNR levels, and an optimized regularization was determined through radiological review. Network generalization toward novel pathology, unobserved during training, was illustrated in five clinical case studies with clinical reference images provided for comparison. CONCLUSION: The rapid 2-minute msEPI-based protocol with tunable ML reconstruction allows for advantageous trade-offs between acquisition speed, SNR, and tissue contrast when compared to the five-fold slower standard clinical reference exam.

Nonaccidental Injury in the Elderly: What Radiologists Need to Know.

Elder abuse may result in serious physical injuries and long-term psychological consequences and can be life threatening. Over the past decade, attention to elder abuse has increased owing to its high prevalence, with one in six people aged 60 years and older experiencing some form of abuse worldwide. Despite this, the detection and reporting rates remain relatively low. While diagnostic imaging is considered critical in detection of child abuse, it is relatively underused in elder abuse. The authors discuss barriers to use of imaging for investigation and diagnosis of elder abuse, including lack of training, comorbidities present in this vulnerable population, and lack of communication among the intra- and interdisciplinary care providers. Moreover, imaging features that should raise clinical concern for elder abuse are reviewed, including certain types of fractures (eg, posterior rib), characteristic soft-tissue and organ injuries (eg, shoulder dislocation), and cases in which the reported mechanism of injury is inconsistent with the imaging findings. As most findings suggesting elder abuse are initially discovered at radiography and CT, the authors focus mainly on use of those modalities. This review also compares and contrasts elder abuse with child abuse. Empowered with knowledge of elderly victims' risk factors, classic perpetrator characteristics, and correlative imaging findings, radiologists should be able to identify potential abuse in elderly patients presenting for medical attention. Future recommendations for research studies and clinical workflow to increase radiologists' awareness of and participation in elder abuse detection are also presented. An invited commentary by Jubanyik and Gettel is available online. Online supplemental material is available for this article. ©RSNA, 2022.

"All-in-one" window/level whole-body computed tomography scan - A faster way to evaluate trauma cases.

PURPOSE: To investigate the accuracy and total assessment time (TAT) of the "All-in-one" (AIO)-window/level setting for whole-body computed tomography (CT) image compared to multiple tissue-specific window/level settings conventionally used for detection of traumatic injuries. METHOD: Contrast-enhanced chest, abdomen, and pelvic CT scans of 50 patients who presented to our emergency department (ED) for major trauma were retrospectively selected. In a simulation of a "wet read" performed at the CT scanner console, 6 readers with different levels of experience had up to 3 min to describe any traumatic finding identified on the CTs. The readers reviewed each patient in two different sessions separated by a washout period to suppress any recall bias from one session to the next. Each scan was reviewed once using the AIO-window/level setting and another time using the conventional bone, lung, and soft tissue window/level display settings, in a randomized order. The CT reports were used as reference standard. RESULTS: Overall, there was no statistically significant difference in the assessment accuracy of the review based on the AIO or the conventional window/level settings (0.89 ± 0.09 vs 0.90 ± 0.08). Using the AIO-window/level settings, TAT was 14.3 s faster when compared with the conventional window/level settings (2.33 ± 0.63 vs 2.57 ± 0.51 min; p < 0.001). CONCLUSIONS: In a time-delimited image review, similar diagnostic accuracy was reached faster using the AIO vs the conventional window/level settings. When providing a "wet read" at the CT console, the ability to identify traumatic injury using a single AIO-window/level may help expedite patient management.

Midline Shift Greater than 3 mm Independently Predicts Outcome After Ischemic Stroke.

BACKGROUND: Cerebral edema is associated with worse outcome after acute stroke; however, the minimum clinically relevant threshold remains unknown. This study aimed to identify the minimal degree of midline shift (MLS) that predicts outcome in a cohort encompassing a broad range of patients with acute stroke. METHODS: Patient-level data from six acute stroke clinical trials were combined with endovascular thrombectomy registries from two academic referral centers, generating a combined cohort of 1977 patients. MLS was extracted from the original trial data or measured on computed tomography or magnetic resonance imaging that was obtained a median of 47.0 h (interquartile range 27.0-75.1 h) after stroke onset. Logistic regression was performed to identify predictors of poor outcome and the minimal clinically relevant MLS threshold. RESULTS: The presence of MLS was a predictor of poor outcome, independent of baseline clinical and demographic factors (adjusted odds ratio 4.46, 95% confidence interval 3.56-5.59, p < 0.001). Examining the full range of MLS values identified, a value of greater than 3 mm was the critical threshold that significantly predicted poor outcome (adjusted odds ratio 3.20 [1.31-7.82], p = 0.011). CONCLUSIONS: These results show that the presence of MLS predicts poor outcome and, specifically, MLS value greater than 3 mm is an important threshold across a variety of clinical settings. These findings may have relevance for the design and interpretation of future trials for antiedema therapies.

Lesion Age Imaging in Acute Stroke: Water Uptake in CT Versus DWI-FLAIR Mismatch.

PURPOSE: In acute ischemic stroke with unknown time of onset, magnetic resonance (MR)-based diffusion-weighted imaging (DWI) and fluid-attenuated inversion recovery (FLAIR) estimates lesion age to guide intravenous thrombolysis. Computed tomography (CT)-based quantitative net water uptake (NWU) may be a potential alternative. The purpose of this study was to directly compare CT-based NWU to magnetic resonance imaging (MRI) at identifying patients with lesion age < 4.5 hours from symptom onset. METHODS: Fifty patients with acute anterior circulation stroke were analyzed with both imaging modalities at admission between 0.5 and 8.0 hours after known symptom onset. DWI-FLAIR lesion mismatch was rated and NWU was measured in admission CT. An established NWU threshold (11.5%) was used to classify patients within and beyond 4.5 hours. Multiparametric MRI signal was compared with NWU using logistic regression analyses. The empirical distribution of NWU was analyzed in a consecutive cohort of patients with wake-up stroke. RESULTS: The median time between CT and MRI was 35 minutes (interquartile range [IQR] = 24-50). The accuracy of DWI-FLAIR mismatch was 68.8% (95% confidence interval [CI] = 53.7-81.3%) with a sensitivity of 58% and specificity of 82%. The accuracy of NWU threshold was 86.0% (95% CI = 73.3-94.2%) with a sensitivity of 91% and specificity of 78%. The area under the curve (AUC) of multiparametric MRI signal to classify lesion age <4.5 hours was 0.86 (95% CI = 0.64-0.97), and the AUC of quantitative NWU was 0.91 (95% CI = 0.78-0.98). Among 87 patients with wake-up stroke, 46 patients (53%) showed low NWU (< 11.5%). CONCLUSION: The predictive power of CT-based lesion water imaging to identify patients within the time window of thrombolysis was comparable to multiparametric DWI-FLAIR MRI. A significant proportion of patients with wake-up stroke exhibit low NWU and may therefore be potentially suitable for thrombolysis. ANN NEUROL 2020;88:1144-1152.

Automated tracking of emergency department abdominal CT findings during the COVID-19 pandemic using natural language processing.

PURPOSE: During the COVID-19 pandemic, emergency department (ED) volumes have fluctuated. We hypothesized that natural language processing (NLP) models could quantify changes in detection of acute abdominal pathology (acute appendicitis (AA), acute diverticulitis (AD), or bowel obstruction (BO)) on CT reports. METHODS: This retrospective study included 22,182 radiology reports from CT abdomen/pelvis studies performed at an urban ED between January 1, 2018 to August 14, 2020. Using a subset of 2448 manually annotated reports, we trained random forest NLP models to classify the presence of AA, AD, and BO in report impressions. Performance was assessed using 5-fold cross validation. The NLP classifiers were then applied to all reports. RESULTS: The NLP classifiers for AA, AD, and BO demonstrated cross-validation classification accuracies between 0.97 and 0.99 and F1-scores between 0.86 and 0.91. When applied to all CT reports, the estimated numbers of AA, AD, and BO cases decreased 43-57% in April 2020 (first regional peak of COVID-19 cases) compared to 2018-2019. However, the number of abdominal pathologies detected rebounded in May-July 2020, with increases above historical averages for AD. The proportions of CT studies with these pathologies did not significantly increase during the pandemic period. CONCLUSION: Dramatic decreases in numbers of acute abdominal pathologies detected by ED CT studies were observed early on during the COVID-19 pandemic, though these numbers rapidly rebounded. The proportions of CT cases with these pathologies did not increase, which suggests patients deferred care during the first pandemic peak. NLP can help automatically track findings in ED radiology reporting.

Turning around cancer: Oncology imaging and implications for emergency department radiology workflow.

PURPOSE: Oncologic imaging in the emergency department (ED) is frequently encountered, including non-acute scans known as "metastatic workups" or "staging" (referred to as "cancer staging computed tomography (CT) exams"). This study examines the impact of oncologic staging CT exams on ED imaging turnaround time (TAT), defined as the time from the end of the CT exam to a final signed radiologist report, as well as order to scan completion time. METHODS: A retrospective review was conducted of all adult patients presenting to an urban, quaternary academic medical center ED from February 2016 to September 2017, who had CT imaging ordered, performed, and interpreted in the ED imaging department. CT exams containing institution-specific cancer descriptors were included. After excluding all acute exams, cancer staging CT exams were compared to a matched cohort of non-oncologic ED CT exams to evaluate median TAT and order to scan completion time using a log transformed multivariable linear regression. RESULTS: Adjusting for age and CT body part, cancer staging CT exams were associated with an independently statistically significant increased median log TAT compared to non-oncologic ED CT exams (114.5 min [IQR 112] versus 69 min [IQR 67], respectively, p < .0001) and an independently statistically significant increased median log initial order to scan completion time (166 min [IQR: 89] vs 119 min [IQR: 93], p < .0001). CONCLUSION: Oncology patients receiving non-acute metastatic workup scans in the ED have a significantly longer TAT compared to non-oncologic ED CT exams as well as longer order to scan completion times.

Nivolumab-induced small bowel obstruction and perforation: a rare but life-threatening side effect of immunotherapy.

We present a case of a 58-year-old female with anti-PD-1 immunotherapy-related small bowel perforation. The patient was on long-term therapy with nivolumab for metastatic non-small cell lung cancer. She presented to the emergency department with acute abdominal pain, in which the CT revealed a short segment of dilated distal ileum proximal to a very short segment of bowel with mural thickening and a perforation near the transition point. The patient underwent subsequent laparotomy, which confirmed the CT findings and revealed a short-segment of friable and dilated loop of distal ileum proximal to a stricture and a small perforation at the transition point. Pathological analysis revealed mural thickening at the site of stricture without evidence of malignancy with focal necrosis and perforation at the transition point. Bowel perforation in the setting of anti-PD-1 immunotherapy is rare, but life-threatening complication, and should be considered in oncology patients on immunotherapy presenting with severe abdominal pain.

Spot and Diffuse Signs: Quantitative Markers of Intracranial Hematoma Expansion at Dual-Energy CT.

Purpose To compare dual-energy CT with iodine quantification to single-energy CT for evaluation of the spot sign for intracranial hematoma expansion. Materials and Methods In this retrospective study, 42 patients (mean age, 66 years ± 15 [standard deviation]; 19 women) were referred for dual-energy CT assessment of intracranial hemorrhage from October 2014 to January 2017. A machine learning approach (naive Bayes classifier) was used to identify iodine markers of extravasation for risk of hematoma expansion. Specificity and sensitivity of these markers were then independently validated in 65 new patients from February 2017 to February 2018. Results Analysis of dual-energy CT images identified two features of iodine extravasation: total iodine concentration within the hematoma (Ih) and focal iodine concentration in the brightest spot in the hematoma (Ibs) as predictors of expansion. The I2 score derived from these features provided a measure of expansion probability. Optimal classification threshold was an I2 score of 20 (95% confidence interval [CI]: 18, 23), leading to correct identification of 39 of 46 (85%; 95% CI: 71%, 94%) of the hematomas on the training set (sensitivity of 79% [11 of 14; 95% CI: 57%, 100%] and specificity of 88% [28 of 32; 95% CI: 76%, 99%]), and 62 of 70 (89%; 95% CI: 79%, 95%) of the hematomas on the validation set (sensitivity of 71% [10 of 14; 95% CI: 48%, 95%] and specificity of 93% [52 of 56; 95% CI: 86%, 100%]). Sensitivity, specificity, and accuracy of conventional spot sign were, respectively, 57% (eight of 14), 90% (29 of 32), and 80% (37 of 46) on the training set and 57% (eight of 14), 83% (47 of 56), and 75% (53 of 70) on the validation set. Conclusion This study identified two quantitative markers of intracranial hemorrhage expansion at dual-energy CT of the brain. The I2 score derived from these markers highlights the utility of dual-energy CT measurements of iodine content for high sensitivity risk assessment. © RSNA, 2018 Online supplemental material is available for this article.

Intravenous thrombolysis in unwitnessed stroke onset: MR WITNESS trial results.

OBJECTIVE: Most acute ischemic stroke (AIS) patients with unwitnessed symptom onset are ineligible for intravenous thrombolysis due to timing alone. Lesion evolution on fluid-attenuated inversion recovery (FLAIR) magnetic resonance imaging (MRI) correlates with stroke duration, and quantitative mismatch of diffusion-weighted MRI with FLAIR (qDFM) might indicate stroke duration within guideline-recommended thrombolysis. We tested whether intravenous thrombolysis ≤4.5 hours from the time of symptom discovery is safe in patients with qDFM in an open-label, phase 2a, prospective study (NCT01282242). METHODS: Patients aged 18 to 85 years with AIS of unwitnessed onset at 4.5 to 24 hours since they were last known to be well, treatable within 4.5 hours of symptom discovery with intravenous alteplase (0.9mg/kg), and presenting with qDFM were screened across 14 hospitals. The primary outcome was the risk of symptomatic intracranial hemorrhage (sICH) with preplanned stopping rules. Secondary outcomes included symptomatic brain edema risk, and functional outcomes of 90-day modified Rankin Scale (mRS). RESULTS: Eighty subjects were enrolled between January 31, 2011 and October 4, 2015 and treated with alteplase at median 11.2 hours (IQR = 9.5-13.3) from when they were last known to be well. There was 1 sICH (1.3%) and 3 cases of symptomatic edema (3.8%). At 90 days, 39% of subjects achieved mRS = 0-1, as did 48% of subjects who had vessel imaging and were without large vessel occlusions. INTERPRETATION: Intravenous thrombolysis within 4.5 hours of symptom discovery in patients with unwitnessed stroke selected by qDFM, who are beyond the recommended time windows, is safe. A randomized trial testing efficacy using qDFM appears feasible and is warranted in patients without large vessel occlusions. Ann Neurol 2018;83:980-993.

Impact of Radiology Report Wording on Care of Patients With Acute Epiploic Appendagitis.

OBJECTIVE. The purpose of this study was to evaluate the association between the diagnostic certainty expressed by the wording of CT report impressions and subsequent use of standard treatment with analgesics versus nonstandard antibiotic administration in patients with acute epiploic appendagitis (EA). MATERIALS AND METHODS. Demographic, clinical, and radiologic data from a 10-year cohort of patients with acute EA were retrospectively analyzed and correlated with standard treatment with analgesics versus nonstandard treatment with antibiotics. A level of certainty was assigned to the CT report language based on the wording of the impression statements by two radiologists; their interreader agreement was assessed with kappa statistics. Bivariate analyses were performed to correlate all variables with antibiotic administration and to assess for collinearity. Multivariate logistic regression was performed to identify independent predictors of antibiotic use in patients with acute EA. RESULTS. Of 124 patients with CT-diagnosed acute EA, 22% (27/124) received antibiotic treatment. After the CT report impressions were evaluated, 27% (34/124) were categorized as low certainty and 73% (90/124) as high certainty (κ = 0.958, p < 0.001). Multivariate regression was significant (p < 0.001, Nagelkerke R2 = 0.249) and found CT report impressions' level of certainty (odds ratio [OR] = 6.1, p < 0.001) and evaluation in an outpatient clinic rather than an emergency department (ED) (OR = 4.4, p = 0.003) to be independent predictors of antibiotic administration for patients with acute EA. Outpatient presentation was also correlated with age, abdominal pain duration, and left-colonic involvement in the bivariate analysis (all p ≤ 0.01). CONCLUSION. The diagnostic certainty conveyed by the wording of CT report impressions correlated with antibiotic treatment decisions for patients with acute EA. Patients whose report impressions expressed low rather than high certainty were six times more likely to receive antibiotic therapy; patients evaluated at outpatient clinics rather than EDs were four times more likely.

Nontraumatic Head and Neck Emergencies.

Head and neck imaging is an intimidating subject for many radiologists because of the complex anatomy and potentially serious consequences of delayed or improper diagnosis of the diverse abnormalities involving this region. The purpose of this article is to help radiologists to understand the intricate anatomy of the head and neck and to review the imaging appearances of a variety of nontraumatic head and neck conditions that bring patients to the emergency department, including acute infectious and inflammatory diseases and acute complications of head and neck neoplasms. These conditions are presented in five sections on the basis of their primary location of involvement: the oral cavity and pharynx, neck, sinonasal tract, orbits, and ears. Important anatomic landmarks are reviewed briefly in each related section.Online supplemental material is available for this article.©RSNA, 2019.

CT for Treatment Selection in Acute Ischemic Stroke: A Code Stroke Primer.

CT is the primary imaging modality used for selecting appropriate treatment in patients with acute stroke. Awareness of the typical findings, pearls, and pitfalls of CT image interpretation is therefore critical for radiologists, stroke neurologists, and emergency department providers to make accurate and timely decisions regarding both (a) immediate treatment with intravenous tissue plasminogen activator up to 4.5 hours after a stroke at primary stroke centers and (b) transfer of patients with large-vessel occlusion (LVO) at CT angiography to comprehensive stroke centers for endovascular thrombectomy (EVT) up to 24 hours after a stroke. Since the DAWN and DEFUSE 3 trials demonstrated the efficacy of EVT up to 24 hours after last seen well, CT angiography has become the operational standard for rapid accurate identification of intracranial LVO. A systematic approach to CT angiographic image interpretation is necessary and useful for rapid triage, and understanding common stroke syndromes can help speed vessel evaluation. Moreover, when diffusion-weighted MRI is unavailable, multiphase CT angiography of collateral vessels and source-image assessment or perfusion CT can be used to help estimate core infarct volume. Both have the potential to allow distinction of patients likely to benefit from EVT from those unlikely to benefit. This article reviews CT-based workup of ischemic stroke for making tPA and EVT treatment decisions and focuses on practical skills, interpretation challenges, mimics, and pitfalls.©RSNA, 2019.