Contemporary Management of Acute Pulmonary Embolism: Evolution of Catheter-based Therapy.

Acute pulmonary embolism (PE) affects more than 100 000 people in the United States annually and is the third leading cardiovascular cause of death. The standard management for PE is systemic anticoagulation therapy. However, a subset of patients experience hemodynamic decompensation, despite conservative measures. Traditionally, these patients have been treated with systemic administration of thrombolytic agents or open cardiac surgery, although attempts at endovascular treatment have a long history that dates back to the 1960s. The technology for catheter-based therapy for acute PE is rapidly evolving, with multiple devices approved over the past decade. Currently available devices fall into two broad categories of treatment methods: catheter-directed thrombolysis and percutaneous suction thrombectomy. Catheter-directed thrombolysis is the infusion of thrombolytic agents directly into the occluded pulmonary arteries to increase local delivery and decrease the total dose. Suction thrombectomy involves the use of small- or large-bore catheters to mechanically aspirate a clot from the pulmonary arteries without the need for a thrombolytic agent. A thorough understanding of the various risk stratification schemes and the available evidence for each device is critical for optimal treatment of this complex entity. Multiple ongoing studies will improve our understanding of the role of catheter-based therapy for acute PE in the next 5-10 years. A multidisciplinary approach through PE response teams has become the management standard at most institutions. An invited commentary by Bulman and Weinstein is available online. Online supplemental material is available for this article. ©RSNA, 2022.

Brain death in a vaccinated patient with COVID-19 infection.

We present a case of brain death in a vaccinated, immunocompromised patient who presented with COVID-19 pneumonia. Imaging was characterized by diffuse cerebral edema, pseudo-subarachnoid hemorrhage, and no antegrade flow above the terminal internal carotid arteries. To our knowledge, this is the first case report with such findings in a vaccinated patient.

Multi-shot acquisitions for stimulus-evoked spinal cord BOLD fMRI.

PURPOSE: To demonstrate the feasibility of 3D multi-shot magnetic resonance imaging acquisitions for stimulus-evoked blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) in the human spinal cord in vivo. METHODS: Two fMRI studies were performed at 3T. The first study was a hypercapnic gas challenge where data were acquired from healthy volunteers using a multi-shot 3D fast field echo (FFE) sequence as well as single-shot multi-slice echo-planar imaging (EPI). In the second study, another cohort of healthy volunteers performed an upper extremity motor task while fMRI data were acquired using a 3D multi-shot acquisition. RESULTS: Both 2D-EPI and 3D-FFE were shown to be sensitive to BOLD signal changes in the cervical spinal cord, and had comparable contrast-to-noise ratios in gray matter. FFE exhibited much less signal drop-out and weaker geometric distortions compared to EPI. In the motor paradigm study, the mean number of active voxels was highest in the ventral gray matter horns ipsilateral to the side of the task and at the spinal level associated with innervation of finger extensors. CONCLUSIONS: Highly multi-shot acquisition sequences such as 3D-FFE are well suited for stimulus-evoked spinal cord BOLD fMRI.

Neutrophil/Lymphocyte Ratio Predicts Increased Risk of Immediate Progressive Disease following Chemoembolization of Hepatocellular Carcinoma.

PURPOSE: To demonstrate that patients with hepatocellular carcinoma (HCC) and elevated baseline neutrophil/lymphocyte ratio (NLR) have a significantly greater risk of progressive disease following initial transarterial chemoembolization. MATERIALS AND METHODS: A total of 190 HCC patients (149 male/41 female) treated with transarterial chemoembolization between July 2013 and July 2017 were reviewed. Mean patient age was 62. Child-Pugh grades were 132 A, 61 B, and 4 C. Tracked criteria included etiology of cirrhosis, tumor number, Barcelona Clinic Liver Cancer score, diameter of the largest 2 tumors, and presence of portal vein thrombosis. Complete blood count with differential before the procedure was used for NLR calculation. Follow-up imaging was performed 2 months after treatment. The modified response evaluation criteria in solid tumors were used to assess response. The association between baseline NLR and tumor response (ordinal modified response evaluation criteria in solid tumors categories) on 2-month follow-up imaging was evaluated using the proportional odds logistic regression model. RESULTS: A total of 194 patients (76.6%) patients had a preprocedural NLR <3.5, and 59 (23%) patients had a preprocedural NLR ≥3.5. There was a statistically significant association between baseline NLR and immediate progression on 2-month follow-up imaging (mean NLR 4.10, 2.76, 2.72, and 2.48 for progressive and stable disease and partial and complete response, respectively; odds ratio 2.1, P = .04). NLR (P = .021) and tumor multiplicity (P = .011) predicted progressive disease at 2-month imaging. CONCLUSIONS: Elevated baseline NLR is associated with higher rates of HCC tumor progression at 2-month follow-up imaging after transarterial chemoembolization.

Arterial Calcification on Wrist Radiographs May Suggest Need for Evaluation of Atherosclerosis in Asymptomatic Individuals.

Asymptomatic individuals with significant coronary artery disease (CAD) are at risk for unanticipated cardiac events including myocardial infarction (MI). Laboratory studies, stress tests, and coronary artery imaging including coronary artery calcium (CAC) scoring evaluate at-risk individuals. Hand and wrist x-rays demonstrating significant arterial wall calcification may provide an additional means to identify asymptomatic individuals at risk for cardiac events. Here we report a case series of patients without known cardiac disease who demonstrated significant calcium deposits in the radial and/or ulnar arteries in radiographs performed for evaluation of their hand conditions. Each series patient was subsequently found to have calcification on coronary artery imaging and an elevated risk of future cardiac events. Our series suggests that peripheral arterial calcifications observed by radiologists and hand specialists may warrant systemic evaluation for atherosclerosis in other areas of the body.

Association between Periprocedural Neutropenia and Early Infection-related Chest Port Removal.

Background Patients who require long-term central venous access can present for port placement with depressed immune function as a result of their treatment or disease process. At present, there is no consensus regarding whether neutropenia at the time of port placement confers a higher risk for early infection-related port removal. Purpose To compare the incidence of early infection-related chest port removal in adults when placed in neutropenic versus nonneutropenic patient groups. Materials and Methods This retrospective cohort study examined 2580 port placements in 1081 men (41.9%) and 1499 women (58.1%) at a single tertiary medical center between June 2007 and July 2017. Mean patient age ± standard deviation was 56 years ± 14 (range, 18-91 years). The electronic medical record was used to identify neutropenia (absolute neutrophil count <1500 cells/mm3) at the time of port placement and incidence of infection-related port removal. Electronic medical record follow-up was conducted for 30 days following port placement. End points were infection-related port removal or death related to port infection within 30 days. Statistical analysis compared the neutropenic (n = 159) and nonneutropenic (n = 2421) patient groups by using a χ2 test for categorical data and a Student t test for continuous variables, with a Fisher exact test to compare incidence of port removal and death related to port infection. Results Ports placed in patients with neutropenia had an infection-related removal rate of 3.8% (six of 159) versus 0.91% (22 of 2421) in patients without neutropenia (P = .003). Patients with neutropenia had a port infection-related death rate of 0.63% (one of 159) versus 0.12% (three of 2421) for patients without neutropenia (P = .22). Conclusion Neutropenia in adults at the time of implantable subcutaneous chest port placement was associated with a higher risk for early infection-related port removal. There was no difference in the incidence of death related to port infection in neutropenic or nonneutropenic populations. © RSNA, 2019 See also the editorial by Johnson in this issue.

Clinical Use of Cerebrovascular Compliance Imaging to Evaluate Revascularization in Patients With Moyamoya.

BACKGROUND: Surgical revascularization is often performed in patients with moyamoya, however routine tools for efficacy evaluation are underdeveloped. The gold standard is digital subtraction angiography (DSA); however, DSA requires ionizing radiation and procedural risk, and therefore is suboptimal for routine surveillance of parenchymal health. OBJECTIVE: To determine whether parenchymal vascular compliance measures, obtained noninvasively using magnetic resonance imaging (MRI), provide surrogates to revascularization success by comparing measures with DSA before and after surgical revascularization. METHODS: Twenty surgical hemispheres with DSA and MRI performed before and after revascularization were evaluated. Cerebrovascular reactivity (CVR)-weighted images were acquired using hypercapnic 3-Tesla gradient echo blood oxygenation level-dependent MRI. Standard and novel analysis algorithms were applied (i) to quantify relative CVR (rCVRRAW), and decompose this response into (ii) relative maximum CVR (rCVRMAX) and (iii) a surrogate measure of the time for parenchyma to respond maximally to the stimulus, CVRDELAY. Measures between time points in patients with good and poor surgical outcomes based on DSA-visualized neoangiogenesis were contrasted (signed-rank test; significance: 2-sided P < .050). RESULTS: rCVRRAW increases (P = .010) and CVRDELAY decreases (P = .001) were observed pre- vs post-revascularization in hemispheres with DSA-confirmed collateral formation; no difference was found pre- vs post-revascularization in hemispheres with poor revascularization. No significant change in rCVRMAX post-revascularization was observed in either group, or between any of the MRI measures, in the nonsurgical hemisphere. CONCLUSION: Improvement in parenchymal compliance measures post-revascularization, primarily attributed to reductions in microvascular response time, is concurrent with collateral formation visualized on DSA, and may be useful for longitudinal monitoring of surgical outcomes.

Are prophylactic antibiotics necessary prior to transarterial chemoembolization for hepatocellular carcinoma in patients with native biliary anatomy?

BACKGROUND AND OBJECTIVES: Prophylactic antibiotics are frequently administered for transarterial chemoembolization (TACE) of hepatocellular carcinoma (HCC). In patients without previous biliary instrumentation, infection risk from TACE is low. We hypothesized that there is a negligible rate of infection in these patients without prophylactic antibiotics. METHODS: We reviewed consecutive patients undergoing TACE between 7/1/2013-6/15/2016. All patients had an intact Sphincter of Oddi, received no peri-procedural antibiotics, and had 30+ days follow-up. Level of arterial selection was recorded. Baseline Child-Pugh (CP) and Barcelona Clinic Liver Cancer (BCLC) scores were recorded. The primary outcome measure was the absence of clinical or imaging findings of hepatic abscess within 30 days. RESULTS: A total of 171 patients underwent 235 TACE procedures. CP scores were A (n = 109), B (n = 47), and C (n = 15). BCLC scores were 0 (n = 1), A (n = 108), B (n = 47), and C (n = 15). TACE was performed segmentally (n = 208) or lobar (n = 27). Three patients died of non-infectious causes before 30 days. No hepatic abscesses developed in evaluable patients: 0/232 infusions. CONCLUSIONS: In patients with HCC and an intact Sphincter of Oddi, TACE was performed safely without prophylactic antibiotics. The majority of the patients were BCLC and CP A/B. Additional study of BCLC and CP C patients is warranted.

Outpatient Transarterial Chemoembolization of Hepatocellular Carcinoma: Review of a Same-Day Discharge Strategy.

PURPOSE: To test the hypothesis that same-day discharge of selected transarterial chemoembolization patients would not increase 30-day readmission rate compared with overnight observation. MATERIALS AND METHODS: With institutional review board approval, 193 hepatocellular carcinoma patients who underwent transarterial chemoembolization from July 2013 to June 2016 were reviewed. Treatment was conventional/lipiodol transarterial chemoembolization with 50 mg doxorubicin/10 mg mitomycin-c/particles or drug-eluting embolics transarterial chemoembolization with 50-75 mg doxorubicin/vial. At 3 hours, patients tolerating oral intake and not requiring intravenous analgesics were considered for discharge. The primary outcome measure was 30-day readmission for observation versus discharge using chi-squared (χ2) analysis. The secondary aim was to identify baseline or treatment variables independently associated with readmission, including Child-Pugh class, medically managed encephalopathy or ascites, patient age (<65 vs ≥65), tumor number (1 or >1), and level of embolization (segmental vs lobar). RESULTS: Patients underwent 261 transarterial chemoembolization procedures. The 30-day readmission rate was not significantly different between observed patients (n = 179, 9.0%) and discharged patients (n = 82, 13.8%; P = .33). Readmission was not related to the selected agent (conventional/lipiodol-transarterial chemoembolization, 11.0% vs drug-eluting embolics transarterial chemoembolization, 7.5%; P = .36). Baseline variables associated with readmission were Child-Pugh B/C (χ2 = 7.9, P < .01), history of encephalopathy (χ2 = 15.4, P < 0.01), and ascites (χ2 = 4.4, P < .05). Patient age (<65 vs ≥65), tumor number (1 vs >1), and level of embolization (segmental vs lobar) were not predictive of readmission (all P > .05). CONCLUSIONS: Same-day discharge after transarterial chemoembolization does not increase the risk of 30-day readmission. Child-Pugh B/C patients, as well as those with ascites or encephalopathy, have the highest risk of readmission.

Hemodynamic mechanisms underlying elevated oxygen extraction fraction (OEF) in moyamoya and sickle cell anemia patients.

Moyamoya is a bilateral, complex cerebrovascular condition characterized by progressive non-atherosclerotic intracranial stenosis and collateral vessel formation. Moyamoya treatment focuses on restoring cerebral blood flow (CBF) through surgical revascularization, however stratifying patients for revascularization requires abilities to quantify how well parenchyma is compensating for arterial steno-occlusion. Globally elevated oxygen extraction fraction (OEF) secondary to CBF reduction may serve as a biomarker for tissue health in moyamoya patients, as suggested in patients with sickle cell anemia (SCA) and reduced oxygen carrying capacity. Here, OEF was measured (TRUST-MRI) to test the hypothesis that OEF is globally elevated in patients with moyamoya (n = 18) and SCA (n = 18) relative to age-matched controls (n = 43). Mechanisms underlying the hypothesized OEF increases were evaluated by performing sequential CBF-weighted, cerebrovascular reactivity (CVR)-weighted, and structural MRI. Patients were stratified by treatment and non-parametric tests applied to compare study variables (significance: two-sided P < 0.05). OEF was significantly elevated in moyamoya participants (interquartile range = 0.38-0.45) compared to controls (interquartile range = 0.29-0.38), similar to participants with SCA (interquartile range = 0.37-0.45). CBF was inversely correlated with OEF in moyamoya participants. Elevated OEF was only weakly related to reductions in CVR, consistent with basal CBF level, rather than vascular reserve capacity, being most closely associated with OEF.

Consensus statement on current and emerging methods for the diagnosis and evaluation of cerebrovascular disease.

Cerebrovascular disease (CVD) remains a leading cause of death and the leading cause of adult disability in most developed countries. This work summarizes state-of-the-art, and possible future, diagnostic and evaluation approaches in multiple stages of CVD, including (i) visualization of sub-clinical disease processes, (ii) acute stroke theranostics, and (iii) characterization of post-stroke recovery mechanisms. Underlying pathophysiology as it relates to large vessel steno-occlusive disease and the impact of this macrovascular disease on tissue-level viability, hemodynamics (cerebral blood flow, cerebral blood volume, and mean transit time), and metabolism (cerebral metabolic rate of oxygen consumption and pH) are also discussed in the context of emerging neuroimaging protocols with sensitivity to these factors. The overall purpose is to highlight advancements in stroke care and diagnostics and to provide a general overview of emerging research topics that have potential for reducing morbidity in multiple areas of CVD.

Treatment of Progressive Herpes Zoster-Induced Vasculopathy with Surgical Revascularization: Effects on Cerebral Hemodynamics.

BACKGROUND: Herpes zoster ophthalmicus (HZO) is caused by reactivation of the herpes simplex virus in the trigeminal nerve. HZO-initiated cerebral vasculopathy is well characterized; however, there are no documented cases that report the efficacy of surgical revascularization for improving cerebral hemodynamics following progressive HZO-induced vasculopathy. We present a case in which quantitative anatomic and hemodynamic imaging were performed longitudinally before and after surgical revascularization in a patient with HZO and vasculopathic changes. CASE DESCRIPTION: A 57-year-old female with history of right-sided HZO presented with left-sided hemiparesis and dysarthria and multiple acute infarcts. Angiography performed serially over a 2-month duration revealed progressive middle cerebral artery stenosis, development of new moyamoya-like lenticulostriate collaterals, and evidence of fibromuscular dysplasia in cervical portions of the internal carotid artery. Hemodynamic imaging revealed right hemisphere decreased blood flow and cerebrovascular reserve capacity. In addition to medical therapy, right-sided surgical revascularization was performed with the intent to reestablish blood flow. Follow-up imaging 13 months post revascularization demonstrated improved blood flow and vascular reserve capacity in the operative hemisphere, which paralleled symptom resolution. CONCLUSIONS: HZO can lead to progressive, symptomatic intracranial stenoses. This report suggests that surgical revascularization techniques can improve cerebral hemodynamics and symptomatology in patients with aggressive disease when medical management is unsuccessful; similar procedures could be considered in managing HZO patients with advanced or progressive vasculopathy.

Lower cardiac index levels relate to lower cerebral blood flow in older adults.

OBJECTIVE: To assess cross-sectionally whether lower cardiac index relates to lower resting cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) among older adults. METHODS: Vanderbilt Memory & Aging Project participants free of stroke, dementia, and heart failure were studied (n = 314, age 73 ± 7 years, 59% male, 39% with mild cognitive impairment). Cardiac index (liters per minute per meter squared) was quantified from echocardiography. Resting CBF (milliliters per 100 grams per minute) and hypercapnia-induced CVR were quantified from pseudo-continuous arterial spin-labeling MRI. Linear regressions with ordinary least-square estimates related cardiac index to regional CBF, with adjustment for age, education, race/ethnicity, Framingham Stroke Risk Profile score (systolic blood pressure, antihypertensive medication use, diabetes mellitus, current cigarette smoking, left ventricular hypertrophy, prevalent cardiovascular disease [CVD], atrial fibrillation), APOE ε4 status, cognitive diagnosis, and regional tissue volume. RESULTS: Lower cardiac index corresponded to lower resting CBF in the left (ß = 2.4, p = 0.001) and right (ß = 2.5, p = 0.001) temporal lobes. Results were similar when participants with prevalent CVD and atrial fibrillation were excluded (left temporal lobe ß = 2.3, p = 0.003; right temporal lobe ß = 2.5, p = 0.003). Cardiac index was unrelated to CBF in other regions assessed (p > 0.25) and CVR in all regions (p > 0.05). In secondary cardiac index × cognitive diagnosis interaction models, cardiac index and CBF associations were present only in cognitively normal participants and affected a majority of regions assessed with effects strongest in the left (p < 0.0001) and right (p < 0.0001) temporal lobes. CONCLUSIONS: Among older adults without stroke, dementia, or heart failure, systemic blood flow correlates with cerebral CBF in the temporal lobe, independently of prevalent CVD, but not CVR.

Cerebral hemodynamics and pseudo-continuous arterial spin labeling considerations in adults with sickle cell anemia.

Sickle cell anemia (SCA) is a genetic disorder resulting in reduced oxygen carrying capacity and elevated stroke risk. Pseudo-continuous arterial spin labeling (pCASL) measures of cerebral blood flow (CBF) may have relevance for stroke risk assessment; however, the effects of elevated flow velocity and reduced bolus arrival time (BAT) on CBF quantification in SCA patients have not been thoroughly characterized, and pCASL model parameters used in healthy adults are often applied to patients with SCA. Here, cervical arterial flow velocities and pCASL labeling efficiencies were computed in adults with SCA (n = 19) and age- and race-matched controls without sickle trait (n = 7) using pCASL in sequence with phase contrast MR angiography (MRA). Controls (n = 7) and a subgroup of patients (n = 8) also underwent multi-post-labeling-delay pCASL for BAT assessment. Mean flow velocities were elevated in SCA adults (velocity = 28.3 ± 4.1 cm/s) compared with controls (velocity = 24.5 ± 3.8 cm/s), and mean pCASL labeling efficiency (α) was reduced in SCA adults (α = 0.72) relative to controls (α = 0.91). In patients, mean whole-brain CBF from phase contrast MRA was 91.8 ± 18.1 ml/100 g/min, while mean pCASL CBF when assuming a constant labeling efficiency of 0.86 was 75.2 ± 17.3 ml/100 g/min (p < 0.01), resulting in a mean absolute quantification error of 23% when a labeling efficiency appropriate for controls was assumed. This difference cannot be accounted for by BAT (whole-brain BAT: control, 1.13 ± 0.06 s; SCA, 1.02 ± 0.09 s) or tissue T1 variation. In conclusion, BAT variation influences pCASL quantification less than elevated cervical arterial velocity and labeling efficiency variation in SCA adults; thus, a lower labeling efficiency (α = 0.72) or subject-specific labeling efficiency should be incorporated for SCA patients.

Noise concerns and post-processing procedures in cerebral blood flow (CBF) and cerebral blood volume (CBV) functional magnetic resonance imaging.

Functional neuroimaging with blood oxygenation level-dependent (BOLD) contrast has emerged as the most popular method for evaluating qualitative changes in brain function in humans. At typical human field strengths (1.5-3.0T), BOLD contrast provides a measure of changes in transverse water relaxation rates in and around capillary and venous blood, and as such provides only a surrogate marker of brain function that depends on dynamic changes in hemodynamics (e.g., cerebral blood flow and volume) and metabolism (e.g., oxygen extraction fraction and the cerebral metabolic rate of oxygen consumption). Alternative functional neuroimaging methods that are specifically sensitive to these constituents of the BOLD signal are being developed and applied in a growing number of clinical and neuroscience applications of quantitative cerebral physiology. These methods require additional considerations for interpreting and quantifying their contrast responsibly. Here, an overview of two popular methods, arterial spin labeling and vascular space occupancy, is presented specifically in the context of functional neuroimaging. Appropriate post-processing and experimental acquisition strategies are summarized with the motivation of reducing sensitivity to noise and unintended signal sources and improving quantitative accuracy of cerebral hemodynamics.

Preclinical TSPO Ligand PET to Visualize Human Glioma Xenotransplants: A Preliminary Study.

Current positron emission tomography (PET) imaging biomarkers for detection of infiltrating gliomas are limited. Translocator protein (TSPO) is a novel and promising biomarker for glioma PET imaging. To validate TSPO as a potential target for molecular imaging of glioma, TSPO expression was assayed in a tumor microarray containing 37 high-grade (III, IV) gliomas. TSPO staining was detected in all tumor specimens. Subsequently, PET imaging was performed with an aryloxyanilide-based TSPO ligand, [18F]PBR06, in primary orthotopic xenograft models of WHO grade III and IV gliomas. Selective uptake of [18F]PBR06 in engrafted tumor was measured. Furthermore, PET imaging with [18F]PBR06 demonstrated infiltrative glioma growth that was undetectable by traditional magnetic resonance imaging (MRI). Preliminary PET with [18F]PBR06 demonstrated a preferential tumor-to-normal background ratio in comparison to 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG). These results suggest that TSPO PET imaging with such high-affinity radiotracers may represent a novel strategy to characterize distinct molecular features of glioma growth, as well as better define the extent of glioma infiltration for therapeutic purposes.

[(18)F]-FLT PET to predict early response to neoadjuvant therapy in KRAS wild-type rectal cancer: a pilot study.

OBJECT: This pilot study evaluated the utility of 3'-deoxy-3'[18F]-fluorothymidine ([(18)F]-FLT) positron emission tomography (PET) to predict response to neoadjuvant therapy that included cetuximab in patients with wild-type KRAS rectal cancers. METHODS: Baseline [(18)F]-FLT PET was collected prior to treatment initiation. Follow-up [(18)F]-FLT was collected after three weekly infusions of cetuximab, and following a combined regimen of cetuximab, 5-FU, and radiation. Imaging-matched biopsies were collected with each PET study. RESULTS: Diminished [(18)F]-FLT PET was observed in 3/4 of patients following cetuximab treatment alone and in all patients following combination therapy. Reduced [(18)F]-FLT PET following combination therapy predicted disease-free status at surgery. Overall, [(18)F]-FLT PET agreed with Ki67 immunoreactivity from biopsy samples and surgically resected tissue, and was predictive of treatment-induced rise in p27 levels. CONCLUSION: These results suggest that [(18)F]-FLT PET is a promising imaging biomarker to predict response to neoadjuvant therapy that included EGFR blockade with cetuximab in patients with rectal cancer.