Search

Stretch activation is defined as a delayed increase in force after rapid stretches. Although there is considerable evidence for stretch activation in isolated cardiac myofibrillar preparations, few studies have measured mechanisms of stretch activation in mammalian skeletal muscle fibers. We measured stretch activation following rapid step stretches [∼1%–4% sarcomere length (SL)] during submaximal Ca2+ activations of rat permeabilized slow-twitch skeletal muscle fibers before and after protein kinase A (PKA), which phosphorylates slow myosin binding protein-C. PKA significantly increased stretch activation during low (∼25%) Ca2+ activation and accelerated rates of delayed force development ( kef) during both low and half-maximal Ca2+ activation. Following the step stretches and subsequent force development, fibers were rapidly shortened to original sarcomere length, which often elicited a shortening-induced transient force overshoot. After PKA, step shortening-induced transient force overshoot increased ∼10-fold following an ∼4% SL shortening during low Ca2+ activation levels. kdf following step shortening also increased after PKA during low and half-maximal Ca2+ activations. We next investigated thin filament regulation of stretch activation. We tested the interplay between cardiac troponin I (cTnI) phosphorylation at the canonical PKA and novel tyrosine kinase sites on stretch activation. Native slow-skeletal Tn complexes were exchanged with recombinant human cTn complex with different human cTnI N-terminal pseudo-phosphorylation molecules: 1) nonphosphorylated wild type (WT), 2) the canonical S22/23D PKA sites, 3) the tyrosine kinase Y26E site, and 4) the combinatorial S22/23D + Y26E cTnI. All three pseudo-phosphorylated cTnIs elicited greater stretch activation than WT. Following stretch activation, a new, elevated stretch-induced steady-state force was reached with pseudo-phosphorylated cTnI. Combinatorial S22/23D + Y26E pseudo-phosphorylated cTnI increased kdf. These results suggest that slow-skeletal myosin binding protein-C (sMyBP-C) phosphorylation modulates stretch activation by a combination of cross-bridge recruitment and faster cycling kinetics, whereas cTnI phosphorylation regulates stretch activation by both redundant and synergistic mechanisms; and, taken together, these sarcomere phosphoproteins offer precision targets for enhanced contractility.

PURPOSE: High-dose methotrexate (HDMTX; > 500 mg/m2) is an important component of lymphoma therapy. Serum MTX monitoring at 48 hours is the standard approach to identify those at increased risk of developing MTX toxicity. Our aim was to characterize the incidence of complications and their association with MTX levels. METHODS: A retrospective review of our institutional electronic medical record was conducted to identify patients with lymphoma who received HDMTX between January 1, 2002, and December 31, 2018. We characterized the incidence of acute kidney injury (AKI), intensive care unit (ICU) admission, length of hospital stay (LOS), and 30-day mortality across 48-hour MTX levels. To establish an association between 48-hour MTX levels and the complications listed, we performed chi-square analysis for dichotomous variables and Kruskal-Wallis for nonparametric data. Receiver operator characteristic curve analysis was performed to identify the MTX level where AKI grade ≥ 2 was more likely. Multivariate logistic regression analysis was performed to identify risk factors for this MTX level. RESULTS: We identified 642 patients with 2,804 cycles of HDMTX. The incidence of AKI was 19.1% with AKI grade ≥ 2 making up 21% of cases. Rates of AKI, ICU admission, and 30-day mortality are associated with elevated 48-hour MTX levels. There was a significant increase in median LOS with elevated MTX levels ( P < .001). Receiver operator characteristic curve analysis for AKI grade ≥ 2 demonstrated a 48-hour MTX level threshold of 1.28 μmol/L. Multivariate logistic regression analysis revealed age, male sex, elevated body surface area, higher MTX dose, monotherapy, and first cycle as independent factors. CONCLUSION: Elevated MTX levels are associated with a significant increased rate of AKI, ICU admission, prolonged LOS, and 30-day mortality. Elevated 48-hour MTX levels, particularly > 1.28 μmol/L, should alert clinicians for complications and to initiate measures to reduce MTX levels.

Following the passage of a tropical cyclone (TC) the changes in temperature, salinity, nutrient concentration, water clarity, pigments and phytoplankton taxa were assessed at 42 stations from eight sites ranging from the open ocean, through the coastal zone and into estuaries. The impacts of the TC were estimated relative to the long-term average (LTA) conditions as well as before and after the TC. Over all sites the most consistent environmental impacts associated with TCs were an average 41% increase in turbidity, a 13% decline in salinity and a 2% decline in temperature relative to the LTA. In the open ocean, the nutrient concentrations, cyanobacteria and picoeukaryote abundances increased at depths between 100 and 150 m for up to 3 months following a TC. While at the riverine end of coastal estuaries, the predominate short-term response was a strong decline in salinity and phytoplankton suggesting these impacts were initially dominated by advection. The more intermediate coastal water-bodies generally experienced declines in salinity, significant reductions in water clarity, plus significant increases in nutrient concentrations and phytoplankton abundance. These intermediate waters typically developed dinoflagellate, diatom or cryptophyte blooms that elevated phytoplankton biomass for 1–3 months following a TC.

To determine the most common presentations of Meckel diverticulum (MD) in children and the performance of imaging modalities in prospective diagnosis.A 28-year retrospective review was performed of children under 18 years of age with MD listed as a diagnosis on pathology and/or surgical reports. The medical record was reviewed to determine presenting clinical scenarios. All imaging performed for each case was reviewed.Seventy-six patients met inclusion criteria. Of the surgically removed MD, most presented with abdominal symptoms (n = 31, 41%); gastrointestinal (GI) bleeding (n = 15, 20%), or both abdominal symptoms and GI bleeding (n = 7, 9%). Twenty-nine percent of MD were discovered incidentally at surgery performed for other reasons. Of the symptomatic MD, only 31% were prospectively diagnosed. For patients with abdominal symptoms, CT had a sensitivity of 13% (3/24) while nuclear medicine (NM) scan had a sensitivity of 0% (0/2). For patients with GI bleed, CT had a sensitivity of 29% (2/7) and NM scan had a sensitivity of 71% (10/14). For patients with both abdominal symptoms and GI bleed, CT was 0% (0/2) and NM scan 75% (3/4) sensitive.MD as a cause of abdominal symptoms and gastrointestinal bleeding may be difficult to diagnose due to nonspecific presentations and nonspecific findings. Most prospectively diagnosed MD are on NM scan in patients with GI bleed with abdominal pain (sensitivity of70%). CT is relatively insensitive for MD in all symptomatology groups (0 to 29%).

Neurodegeneration refers to the selective and progressive loss-of-function and atrophy of neurons, and is present in disorders such as Alzheimer’s, Huntington’s, and Parkinson’s disease. Although each disease presents with a unique pattern of neurodegeneration, and subsequent disease phenotype, increasing evidence implicates alterations in energy usage as a shared and core feature in the onset and progression of these disorders. Indeed, disturbances in energy metabolism may contribute to the vulnerability of neurons to apoptosis. In this review we will outline these disturbances in glucose metabolism, and how fatty acids are able to compensate for this impairment in energy production in neurodegenerative disorders. We will also highlight underlying mechanisms that could contribute to these alterations in energy metabolism. A greater understanding of these metabolism-neurodegeneration processes could lead to improved treatment options for neurodegenerative disease patients.

Purpose: To predict pathologic complete response (pCR) in breast cancer patients undergoing neoadjuvant chemotherapy (NAC), from baseline and early-treatment DCE-MRI scans, in the context of the ACRIN 6698/I-SPY 2 BMMR2 challenge. Materials and Methods: The BMMR2 dataset consists of 191 patients undergoing NAC for locally advanced breast cancer as part of the ACRIN 6698/I-SPY 2 trial. DCE-MRI was obtained at time points T0 (pre-NAC), T1 (3 weeks), and T2 (12 weeks). The BMMR2 challenge provided the MRI scans, tumor annotations, and limited clinical and demographic information. The data were split 60/40; using the 60% training data, the task was to develop models to predict pCR; the competition was for best area under the curve (AUC) when applied to the 40% unseen test data. Using the publicly available CaPTk software we calculated 3 types of radiomic features within the segmented tumor volume: 1) texture of the signal enhancement ratio (SER) kinetic map of T0 images; 2) texture of the difference between the T1 kinetic maps (PE, WIS, WOS, and SER) and corresponding T0 maps; 3) texture of the difference between the T1 kinetic maps and the corresponding T0 maps, with T1 scans deformably registered to T0 scans. ComBat harmonization was applied to the extracted features to account for MRI acquisition differences. We computed the tumor longest diameter, functional tumor volume (FTV), and clinical tumor size each at T0 and T1. We modeled pCR via logistic regression. Using the training data alone, with the criteria of performance in univariable modeling and low collinearity, we selected radiomic features and clinical, demographic, and size covariates. We then performed PCA on the combined set of selected radiomic features and size covariates. We evaluated multivariable models including the selected clinical covariates in combination with the first few PCs via cross-validated AUC (5-fold, 200 repetitions) on the training data. The best models were submitted for independent evaluation on the unseen test data of the BMMR2 challenge. Results: Of the available clinical covariates, only hormone receptor (HR)± and human epidermal growth factor receptor 2 (HER2)± had any association with pCR. We retained these in all models, and performed PCA on the set combining the best-performing features and the size variables FTV at T0, FTV at T1, and longest diameter at T1. Models based on the first few PCs, HR, and HER2, had training AUCs in 0.78–0.81. Our best-performing model had an AUC on test data of 0.84, using the covariates PCs 1–5, HR, and HER2 (Table 1). Conclusions: Our preliminary results suggest that radiomic phenotyping of changes in tumor heterogeneity can accurately predict pCR early in the course of NAC. Future analysis with larger samples from ISPY-2 could also examine the effect of different therapies, including targeted therapy and immunotherapy. Table 1: Performance of candidate logistic regression models on training and test data. AUC: Area under receiver operating characteristic curve. * Mean 5-fold cross-validated AUC across 200 replicates. † Competition best-performing predictions. Citation Format: Eric A. Cohen, Rhea D. Chitalia, Snekha Thakran, Walter C. Mankowski, Alex Anh-Tu Nguyen, Hannah Horng, Elizabeth S. McDonald, Michael Feldman, Angela DeMichele, Despina Kontos. Title: Characterizing Changes in Tumor Heterogeneity via Radiomic Phenotyping for Predicting Response to Neoadjuvant Chemotherapy for Locally Advanced Breast Cancer: Preliminary Results from the ACRIN 6698/I-SPY 2 trial [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD16-08.

Objective To assess the frequency, management, and early outcomes of COVID-19 vaccine–related adenopathy on breast MRI. Methods This IRB-exempt retrospective study reviewed patients who underwent breast MRI following COVID-19 vaccine approval in the U.S. from December 14, 2020, to April 11, 2021 (N = 1912) and compared patients who underwent breast MRI the year prior to the pandemic, March 13, 2019, to March 12, 2020 (N = 5342). Study indication, patient age, date of study, date and type of vaccination(s), time difference between study and vaccinations, lymph node–specific and overall management recommendations, and outcomes of additional examinations were recorded. Differences in the final assessment categories between the subjects scanned pre-pandemic and post-vaccine were compared using the Fisher exact test. Results Vaccine-related adenopathy was mentioned in 67 breast MRI reports; only 1 in the pre-pandemic group. There were no clinically relevant differences in patient demographics between groups. There was a statistically significant increase in BI-RADS 0 assessments between the pre-pandemic and post-vaccine approval groups—0.8% (45/5342) versus 1.8% (34/1912) (P = 0.001) and BI-RADS 3 assessments—6.5% (348/5342) versus 9.2% (176/1912) (P < 0.0001). Of the 29 patients who underwent additional imaging (range, 2–94 days following MRI) and the 2 patients who underwent biopsy, 47% (31/66), none were found to have malignant adenopathy. Conclusion COVID-19 vaccination is associated with transient axillary adenopathy of variable duration. This leads to additional imaging in women undergoing breast MRI, so far with benign outcomes, and this may affect audits of outcomes of MRI.

Larval stomatopods have generally been described as having a typical larval crustacean compound eye, which lacks the visual pigment diversity and morphological specializations of the well-studied stomatopod adult eye. However, recent work has suggested that larval stomatopod eyes are more complex than previously described. In this study, we provide physiological and behavioral evidence of at least three distinct photoreceptor classes in three species of larval stomatopods: Gonodactylellus n. sp., Gonodactylaceus falcatus and Pullosquilla n. sp. First, electroretinogram recordings were used to measure the spectral sensitivity of each species. Evidence for at least three spectral classes were identified in each: an ultraviolet, peaking at 340–376 nm; a short-wavelength blue, peaking at 455–464 nm; and a long-wavelength orange, peaking at 576–602 nm. Next, the behavioral response to light was investigated. We found that each species demonstrated positive phototactic responses to monochromatic stimuli across the UV–visible spectrum. In wavelength preference trials, distinct preferences among species were identified when different colored light stimuli were presented simultaneously. All species displayed a strong response to the UV stimulus, as well as responses to blue and orange stimuli, although at different response strengths, but no response to green. The results of this study demonstrate that larval stomatopods not only have multiple physiologically active spectral classes but they also display clear and distinct responses to wavelengths across the spectrum. We propose that the spectral classes demonstrated in each are related to visually guided ecological tasks of the larvae, which may differ between species.

Purpose:Identifying imaging phenotypes and understanding their relationship with prognostic markers and patient outcomes can allow for a noninvasive assessment of cancer. The purpose of this study was to identify and validate intrinsic imaging phenotypes of breast cancer heterogeneity in preoperative breast dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) scans and evaluate their prognostic performance in predicting 10 years recurrence.Experimental Design:Pretreatment DCE-MRI scans of 95 women with primary invasive breast cancer with at least 10 years of follow-up from a clinical trial at our institution (2002–2006) were retrospectively analyzed. For each woman, a signal enhancement ratio (SER) map was generated for the entire segmented primary lesion volume from which 60 radiomic features of texture and morphology were extracted. Intrinsic phenotypes of tumor heterogeneity were identified via unsupervised hierarchical clustering of the extracted features. An independent sample of 163 women diagnosed with primary invasive breast cancer (2002–2006), publicly available via The Cancer Imaging Archive, was used to validate phenotype reproducibility.Results:Three significant phenotypes of low, medium, and high heterogeneity were identified in the discovery cohort and reproduced in the validation cohort (P < 0.01). Kaplan–Meier curves showed statistically significant differences (P < 0.05) in recurrence-free survival (RFS) across phenotypes. Radiomic phenotypes demonstrated added prognostic value (c = 0.73) predicting RFS.Conclusions:Intrinsic imaging phenotypes of breast cancer tumor heterogeneity at primary diagnosis can predict 10-year recurrence. The independent and additional prognostic value of imaging heterogeneity phenotypes suggests that radiomic phenotypes can provide a noninvasive characterization of tumor heterogeneity to augment personalized prognosis and treatment.

The heart’s pumping capacity is determined by myofilament power generation. Power is work done per unit time and measured as the product of force and velocity. At a sarcomere level, these contractile properties are linked to the number of attached cross-bridges and their cycling rate, and many signaling pathways modulate one or both factors. We previously showed that power is increased in rodent permeabilized cardiac myocytes following PKA-mediated phosphorylation of myofibrillar proteins. The current study found that that PKA increased power by ∼30% in permeabilized cardiac myocyte preparations (n = 8) from human failing hearts. To address myofilament molecular specificity of PKA effects, mechanical properties were measured in rat permeabilized slow-twitch skeletal muscle fibers before and after exchange of endogenous slow skeletal troponin with recombinant human Tn complex that contains cardiac (c)TnT, cTnC and either wildtype (WT) cTnI or pseudo-phosphorylated cTnI at sites Ser23/24Asp, Tyr26Glu, or the combinatorial Ser23/24Asp and Tyr26Glu. We found that cTnI Ser23/24Asp, Tyr26Glu, and combinatorial Ser23/24Asp and Tyr26Glu were sufficient to increase power by ∼20%. Next, we determined whether pseudo-phosphorylated cTnI at Ser23/24 was sufficient to increase power in cardiac myocytes from human failing hearts. Following cTn exchange that included cTnI Ser23/24Asp, power output increased ∼20% in permeabilized cardiac myocyte preparations (n = 6) from the left ventricle of human failing hearts. These results implicate cTnI N-terminal phosphorylation as a molecular regulator of myocyte power and could serve as a regional target for small molecule therapy to unmask myocyte power reserve capacity in human failing hearts.

Legends for supplemental figures and tables

Supplementary data includes appendix of extracted Radiomic features. Figure S1 shows a summary of patient characteristics. Figure S2 shows the radiomic analysis workflow. Figure S3 shows representative cases from heterogeneity phenotypes. Figure S4 shows independent validation of intrinsic imaging phenotypes of tumor heterogeneity.

Supplemental material and methods.

Despite the availability of PARP inhibitors for cancer therapy, a biomarker to clearly stratify patients for selection of this treatment remains lacking. Here we describe a radiotracer-based method that addresses this issue, using the novel compound [125I]KX1 as a PARP-1–selective radiotracer that can accurately measure PARP-1 expression in vitro and in vivo. The pharmacologic properties of the PARP radiotracer [125I]KX1 was characterized in multiple cell lines where single-agent sensitivity was correlated with [125I]KX1 binding to PARP-1. In vivo evaluation of [125I]KX1 verified in vitro results, validating PARP radiotracers to define PARP-1 enzyme expression as an in vivo biomarker. Notably, PARP-1 expression as quantified by [125I]KX1 correlated positively with the cytotoxic sensitivity of cell lines evaluated with PARP inhibitors. Overall, our results defined a novel technology with the potential to serve as a companion diagnostic to identify patients most likely to respond therapeutically to a PARP inhibitor. Cancer Res; 76(15); 4516–24. ©2016 AACR.

SI-figure 1: "Chemical synthesis scheme for [125I]KX1." SI-figure 2: "Whole western blots and regions of interest generated around the protein of interest." SI-figure 3: "Kinetic analysis association and dissociation curves of [125I]KX1." SI-table 1: "Summary table for cell lines used in vitro to validate [125I]KX1 as a marker of PARP-1 expression." SI-table 2: "Competitive inhibition (Ki) Values are presented for each PARP inhibitor as measured in the different cell lines." SI-table 3: "Experimental association and dissociation values of [125I]KX1." SI-table 4: "Dissociation constants for [125I]KX1 in multiple cell lines." SI-table 5: " EC50 values for PARP inhibitors in cell lines evaluated."

BACKGROUND: Concerns over the neurotoxic potential of retained gadolinium in brain tissues after intravenous gadolinium-based contrast agent (GBCA) administration have led to pronounced worldwide use changes, yet the clinical sequelae of gadolinium retention remain undefined. PURPOSE: To assess clinical and neurologic effects and potential neurotoxicity of gadolinium retention in rats after administration of various GBCAs. MATERIALS AND METHODS: From March 2017 through July 2018, 183 male Wistar rats received 20 intravenous injections of 2.5 mmol per kilogram of body weight (80 human equivalent doses) of various GBCAs (gadodiamide, gadobenate, gadopentetate, gadoxetate, gadobutrol, gadoterate, and gadoteridol) or saline over 4 weeks. Rats were evaluated 6 and 34 weeks after injection with five behavioral tests, and inductively coupled plasma mass spectrometry, transmission electron microscopy, and histopathology were performed on urine, serum, cerebrospinal fluid (CSF), basal ganglia, dentate nucleus, and kidney samples. Dunnett post hoc test and Wilcoxon rank sum test were used to compare differences between treatment groups. RESULTS: No evidence of differences in any behavioral test was observed between GBCA-exposed rats and control animals at either 6 or 34 weeks (P = .08 to P = .99). Gadolinium concentrations in both neuroanatomic locations were higher in linear GBCA-exposed rats than macrocyclic GBCA-exposed rats at 6 and 34 weeks (P < .001). Gadolinium clearance over time varied among GBCAs, with gadobutrol having the largest clearance (median: 62% for basal ganglia, 70% for dentate) and gadodiamide having no substantial clearance. At 34 weeks, gadolinium was largely cleared from the CSF and serum of gadodiamide-, gadobenate-, gadoterate-, and gadobutrol-exposed rats, especially for the macrocyclic agents (range: 70%–98% removal for CSF, 34%–94% removal for serum), and was nearly completely removed from urine (range: 96%–99% removal). Transmission electron microscopy was used to detect gadolinium foci in linear GBCA-exposed brain tissue, but no histopathologic differences were observed for any GBCA. CONCLUSION: In this rat model, no clinical evidence of neurotoxicity was observed after exposure to linear and macrocyclic gadolinium-based contrast agents at supradiagnostic doses. © RSNA, 2022 Online supplemental material is available for this article.

Introduction Interference screw fixation of soft tissue grafts is commonly used in anterior cruciate ligament (ACL) reconstruction. The purpose of this study was to determine whether including suture material at the graft–screw interface affects ultimate fixation strength of soft tissue grafts using a tibialis anterior tendon allograft model. Materials and Methods Forty fresh-frozen human tibialis anterior tendon allografts were fixed to rigid polyurethane foam simulating the tibial tunnel. Twenty grafts underwent fixation with interference screws and 20 with interference bolts. Within each group, 10 grafts had suture in contact with either the screw or bolt. A load-to-failure test was then performed at a rate of 200 mm/min. Results The group of allografts with sutures in the tibial tunnel had significantly higher load to failure than the group without sutures. Using interference screw fixation, failure load of the grafts without sutures in the tunnel (535.2 ± 73.40 N) was significantly lower (P = .001) than with sutures in the tunnel (696.3 ± 110.0 N). Using interference bolt fixation, failure load of the grafts without sutures in the tunnel (613.0 ± 83.46 N) was significantly lower (P Conclusions In a biomechanical model, suture within the tibial tunnel enhances fixation strength with both interference screw and bolt fixation for soft tissue tibialis anterior allografts. Additionally, there was no difference in load to failure when comparing failure of a screw with suture in the tunnel with an interference bolt without suture. Due to improved biomechanical properties, incorporation of suture in the bone–graft interface should be considered when performing soft tissue ACL allograft reconstructions. Failure at the tibial bone–graft interface is a known complication of ACL reconstruction, and incorporation of suture within the interface should be considered for improved biomechanical properties.

Background The pass rate on the American Board of Internal Medicine (ABIM) nephrology certifying exam has declined and is among the lowest of all internal medicine (IM) subspecialties. In recent years, there have also been fewer applicants for the nephrology fellowship match. Methods This retrospective observational study assessed how changes between 2010 and 2019 in characteristics of 4094 graduates of US ACGME-accredited nephrology fellowship programs taking the ABIM nephrology certifying exam for the first time, and how characteristics of their fellowship programs were associated with exam performance. The primary outcome measure was performance on the nephrology certifying exam. Fellowship program pass rates over the decade were also studied. Results Lower IM certifying exam score, older age, female sex, international medical graduate (IMG) status, and having trained at a smaller nephrology fellowship program were associated with poorer nephrology certifying exam performance. The mean IM certifying exam percentile score among those who subsequently took the nephrology certifying exam decreased from 56.7 (SD, 27.9) to 46.1 (SD, 28.7) from 2010 to 2019. When examining individuals with comparable IM certifying exam performance, IMGs performed less well than United States medical graduates (USMGs) on the nephrology certifying exam. In 2019, only 57% of nephrology fellowship programs had aggregate 3-year certifying exam pass rates ≥80% among their graduates. Conclusions Changes in IM certifying exam performance, certain trainee demographics, and poorer performance among those from smaller fellowship programs explain much of the decline in nephrology certifying exam performance. IM certifying exam performance was the dominant determinant.

Background Suppression of background parenchymal enhancement (BPE) is commonly observed after neoadjuvant chemotherapy (NAC) at contrast-enhanced breast MRI. It was hypothesized that nonsuppressed BPE may be associated with inferior response to NAC. Purpose To investigate the relationship between lack of BPE suppression and pathologic response. Materials and Methods A retrospective review was performed for women with menopausal status data who were treated for breast cancer by one of 10 drug arms (standard NAC with or without experimental agents) between May 2010 and November 2016 in the Investigation of Serial Studies to Predict Your Therapeutic Response with Imaging and Molecular Analysis 2, or I-SPY 2 TRIAL (NCT01042379). Patients underwent MRI at four points: before treatment (T0), early treatment (T1), interregimen (T2), and before surgery (T3). BPE was quantitatively measured by using automated fibroglandular tissue segmentation. To test the hypothesis effectively, a subset of examinations with BPE with high-quality segmentation was selected. BPE change from T0 was defined as suppressed or nonsuppressed for each point. The Fisher exact test and the Z tests of proportions with Yates continuity correction were used to examine the relationship between BPE suppression and pathologic complete response (pCR) in hormone receptor (HR)-positive and HR-negative cohorts. Results A total of 3528 MRI scans from 882 patients (mean age, 48 years ± 10 [standard deviation]) were reviewed and the subset of patients with high-quality BPE segmentation was determined (T1, 433 patients; T2, 396 patients; T3, 380 patients). In the HR-positive cohort, an association between lack of BPE suppression and lower pCR rate was detected at T2 (nonsuppressed vs suppressed, 11.8% [six of 51] vs 28.9% [50 of 173]; difference, 17.1% [95% CI: 4.7, 29.5]; P = .02) and T3 (nonsuppressed vs suppressed, 5.3% [two of 38] vs 27.4% [48 of 175]; difference, 22.2% [95% CI: 10.9, 33.5]; P = .003). In the HR-negative cohort, patients with nonsuppressed BPE had lower estimated pCR rate at all points, but the P values for the association were all greater than .05. Conclusions In hormone receptor-positive breast cancer, lack of background parenchymal enhancement suppression may indicate inferior treatment response. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Philpotts in this issue.

Pneumocephalus is a condition defined by air present in the intracranial space. There are several causes of pneumocephalus, however this is a case of a patient who developed pneumocephalus following a cervical epidural steroid injection. Uniquely, this patient's chief complaint was sudden onset of syncope, and respiratory arrest following the injection. The diagnosis was made by CT, and conservative treatment was used for resolution of the condition. Patients with pneumocephalus can present with a wide range of neurologic symptoms, and prompt recognition and treatment are key to preventing irreversible neurologic damage.