April 2015Advances in MR Imaging for Cervical Spondylotic Myelopathy.
PURPOSE: To outline the pathogenesis of cervical spondylotic myelopathy (CSM), the correlative abnormalities observed on standard magnetic resonance imaging (MRI), the biological implications and current status of diffusion tensor imaging (DTI), and MR spectroscopy (MRS) as clinical tools, and future directions of MR technology in the management of CSM patients. METHODS: A systematic review of the pathogenesis and current state-of-the-art in MR imaging technology for CSM was performed.
April 2015The Risks of Innovation in Health Care.
Innovation in health care creates risks that are unevenly distributed. An evolutionary analogy using species to represent business models helps categorize innovation experiments and their risks. This classification reveals two qualitative categories: early and late diversification experiments. Early diversification has prolific innovations with high risk because they encounter a "decimation" stage, during which most experiments disappear. Participants face high risk. The few decimation survivors can be sustaining or disruptive according to Christensen's criteria. Survivors enter late diversification, during which they again expand, but within a design range limited to variations of the previous surviving designs. Late diversifications carry lower risk. The exception is when disruptive survivors "diversify," which amplifies their disruption. Health care and radiology will experience both early and late diversifications, often simultaneously. Although oversimplifying Christensen's concepts, early diversifications are likely to deliver disruptive innovation, whereas late diversifications tend to produce sustaining innovations. Current health care consolidation is a manifestation of late diversification. Early diversifications will appear outside traditional care models and physical health care sites, as well as with new science such as molecular diagnostics. They warrant attention because decimation survivors will present both disruptive and sustaining opportunities to radiology. Radiology must participate in late diversification by incorporating sustaining innovations to its value chain. Given the likelihood of disruptive survivors, radiology should seriously consider disrupting itself rather than waiting for others to do so. Disruption entails significant modifications of its value chain, hence, its business model, for which lessons may become available from the pharmaceutical industry's current simultaneous experience with early and late diversifications.
April 2015ACR Appropriateness Criteria Indeterminate Renal Mass.
Renal masses are increasingly detected in asymptomatic individuals as incidental findings. An indeterminate renal mass is one that cannot be diagnosed confidently as benign or malignant at the time it is discovered. CT, ultrasonography, and MRI of renal masses with fast-scan techniques and intravenous (IV) contrast are the mainstays of evaluation. Dual-energy CT, contrast-enhanced ultrasonography, PET/CT, and percutaneous biopsy are all technologies that are gaining traction in the characterization of the indeterminate renal mass. In cases in which IV contrast cannot be used, whether because of IV contrast allergy or renal insufficiency, renal mass classification with CT is markedly limited. In the absence of IV contrast, ultrasonography, MRI, and biopsy have some advantages. Owing to the low malignant and metastatic potential of small renal cell carcinomas (≤4 cm in diameter), active surveillance is additionally emerging as a diagnostic strategy for patients who have high surgical risk or limited life expectancy. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 3 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and application by the panel of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.
April 2015Meniere's Disease: Histopathology, Cytochemistry, and Imaging.
Meniere's disease is a poorly understood, disabling syndrome causing spells of vertigo, hearing fluctuation, tinnitus, and aural fullness. In this paper, we present a review of the histopathology, cytochemistry, and imaging of Meniere's disease. Histopathology is significant for neuroepithelial damage with hair cell loss, basement membrane thickening, and perivascular microvascular damage. Cytochemical alterations are significant for altered AQP4 and AQP6 expression in the supporting cell, and altered cochlin and mitochondrial protein expression. Current developments include imaging techniques to determine the degree and presence of endolymphatic hydrops, and future studies will endeavor to correlate the observance of hydrops with clinical findings.
April 2015Brain Biopsy in Neurologic Decline of Unknown Etiology.
Brain biopsies have an uncertain role in the diagnosis of patients with dementia or neurologic decline of unknown etiology. They are often performed only after an exhaustive panel of less invasive tests and procedures have failed to provide a definitive diagnosis. The objective of this study was to evaluate the sensitivity of brain biopsies in this patient group through the retrospective analysis of 53 brain biopsies performed for neurologic disease of unknown etiology at a single tertiary care institution between December 2001 and December 2011. Patients with known nonlymphomatous neoplasms thought to be associated with the neurologic symptoms or with immunodeficiency were excluded from the study. Furthermore, the clinical presentation, imaging and laboratory tests were compared between diagnostic groups to identify factors more likely to yield a diagnosis. Sixty percent of the biopsies were diagnostic (32 of 53), with the most common histologic diagnosis of central nervous system lymphoma in 14 of 53 patients (26% of total) followed by infarct in four subjects (7.5%). A few patients were found to have rare and unsuspected diseases such as lymphomatosis cerebri, neurosarcoidosis and neuroaxonal leukodystrophy. Complications from biopsy were uncommon and included hemorrhage and infection with abscess formation at the biopsy site. These results suggest that brain biopsies may be useful in difficult cases in which less invasive measures have been unable to yield a definitive diagnosis.
April 2015Criteria for Identifying Radiologists with Acceptable Screening Mammography Interpretive Performance on Basis of Multiple Performance Measures.
OBJECTIVE: Using a combination of performance measures, we updated previously proposed criteria for identifying physicians whose performance interpreting screening mammography may indicate suboptimal interpretation skills. MATERIALS AND METHODS: In this study, six expert breast imagers used a method based on the Angoff approach to update criteria for acceptable mammography performance on the basis of two sets of combined performance measures: set 1, sensitivity and specificity for facilities with complete capture of false-negative cancers; and set 2, cancer detection rate (CDR), recall rate, and positive predictive value of a recall (PPV1) for facilities that cannot capture false-negative cancers but have reliable cancer follow-up information for positive mammography results. Decisions were informed by normative data from the Breast Cancer Surveillance Consortium (BCSC).
April 2015Prevalence of Coronary Artery Disease Evaluated by Coronary CT Angiography in Women with Mammographically Detected Breast Arterial Calcifications.
To assess the correlation between breast arterial calcifications (BAC) on digital mammography and the extent of coronary artery disease (CAD) diagnosed with dual source coronary computed tomography angiography (CTA) in a population of women both symptomatic and asymptomatic for coronary artery disease. 100 consecutive women (aged 34 - 86 years) who underwent both coronary CTA and digital mammography were included in the study. Health records were reviewed to determine the presence of cardiovascular risk factors such as hypertension, hyperlipidemia, diabetes mellitus, and smoking. Digital mammograms were reviewed for the presence and degree of BAC, graded in terms of severity and extent. Coronary CTAs were reviewed for CAD, graded based on the extent of calcified and non-calcified plaque, and the degree of major vessel stenosis. A four point grading scale was used for both coronary CTA and mammography. The overall prevalence of positive BAC and CAD in the studied population were 12% and 29%, respectively. Ten of the 12 patients with moderate or advanced BAC on mammography demonstrated moderate to severe CAD as determined by coronary CTA. For all women, the positive predictive value of BAC for CAD was 0.83 and the negative predictive value was 0.78. The presence of BAC on mammography appears to correlate with CAD as determined by coronary CTA (Spearman's rank correlation coefficient = 0.48, p<.000001). Using logistic regression, the inclusion of BAC as a feature in CAD predication significantly increased classification results (p=0.04).
April 2015Role of the Quantitative Imaging Biomarker Alliance in Optimizing CT for the Evaluation of Lung Cancer Screen-Detected Nodules.
The Quantitative Imaging Biomarker Alliance (QIBA) is a multidisciplinary consortium sponsored by the RSNA to define processes that enable the implementation and advancement of quantitative imaging methods described in a QIBA profile document that outlines the process to reliably and accurately measure imaging features. A QIBA profile includes factors such as technical (product-specific) standards, user activities, and relationship to a clinically meaningful metric, such as with nodule measurement in the course of CT screening for lung cancer. In this report, the authors describe how the QIBA approach is being applied to the measurement of small pulmonary nodules such as those found during low-dose CT-based lung cancer screening. All sources of variance with imaging measurement were defined for this process. Through a process of experimentation, literature review, and assembly of expert opinion, the strongest evidence was used to define how to best implement each step in the imaging acquisition and evaluation process. This systematic approach to implementing a quantitative imaging biomarker with standardized specifications for image acquisition and postprocessing for a specific quantitative measurement of a pulmonary nodule results in consistent performance characteristics of the measurement (eg, bias and variance). Implementation of the QIBA small nodule profile may allow more efficient and effective clinical management of the diagnostic workup of individuals found to have suspicious pulmonary nodules in the course of lung cancer screening evaluation.
April 2015Imaging-histologic Discordance at Percutaneous Biopsy of the Lung.
RATIONALE AND OBJECTIVES: The purpose of this study was to quantify the degree of imaging-histologic discordance in a cohort of patients undergoing computed tomography (CT)-guided lung biopsy for focal lung disease. MATERIALS AND METHODS: A retrospective review was performed of 186 patients who underwent percutaneous lung biopsy of a parenchymal lesion at our institution between January and December 2009. Diagnostic radiology reports of CT or positron emission tomography-CTs performed before biopsy were used to classify the lesion as malignant or benign by five readers. Pathology reports of the biopsied lesions were classified by three readers. Inter-reader agreement and imaging-histologic concordance were quantified using kappa statistics. Discordant benign cases were then revisited to determine downstream effects.
April 2015Arterial Spin-labeling Perfusion MRI Stratifies Progression-free Survival and Correlates with Epidermal Growth Factor Receptor Status in Glioblastoma.
BACKGROUND AND PURPOSE: Glioblastoma is a common primary brain tumor with a poor but variable prognosis. Our aim was to investigate the feasibility of MR perfusion imaging by using arterial spin-labeling for determining the prognosis of patients with glioblastoma. MATERIALS AND METHODS: Pseudocontinuous arterial spin-labeling with 3D background-suppressed gradient and spin-echo was acquired before surgery on 53 patients subsequently diagnosed with glioblastoma. The calculated CBF color maps were visually evaluated by 3 independent readers blinded to patient history. Pathologic and survival data were correlated with CBF map findings. Arterial spin-labeling values in tumor tissue were also quantified by using manual fixed-size ROIs.
April 2015Incremental Value of Secretin-enhanced Magnetic Resonance Cholangiopancreatography in Detecting Ductal Communication in a Population with High Prevalence of Small Pancreatic Cysts.
PURPOSE: We investigated the incremental diagnostic yield of S-MRCP in a population with high prevalence of small pancreatic cysts. METHODS: Standard MRCP protocol was performed with and without secretin using 1.5 T units in subjects undergoing pancreatic screening because of a strong family history of pancreatic cancer as part of the multicenter Cancer of the Pancreas Screening-3 trial (CAPS 3). All studies were reviewed prospectively by two independent readers who recorded the presence and number of pancreatic cysts, the presence of visualized ductal communication before and after secretin, and the degree of confidence in the diagnoses.
April 2015SolitaireTM with the Intention for Thrombectomy as Primary Endovascular Treatment for Acute Ischemic Stroke (SWIFT PRIME) Trial: Protocol for a Randomized, Controlled, Multicenter Study Comparing the Solitaire Revascularization Device with IV tPA with IV tPA Alone in Acute Ischemic Stroke.
RATIONALE: Early reperfusion in patients experiencing acute ischemic stroke is critical, especially for patients with large vessel occlusion who have poor prognosis without revascularization. Solitaire™ stent retriever devices have been shown to immediately restore vascular perfusion safely, rapidly, and effectively in acute ischemic stroke patients with large vessel occlusions. AIM: The aim of the study was to demonstrate that, among patients with large vessel, anterior circulation occlusion who have received intravenous tissue plasminogen activator, treatment with Solitaire revascularization devices reduces degree of disability 3 months post stroke. DESIGN: The study is a global multicenter, two-arm, prospective, randomized, open, blinded end-point trial comparing functional outcomes in acute ischemic stroke patients who are treated with either intravenous tissue plasminogen activator alone or intravenous tissue plasminogen activator in combination with the Solitaire device. Up to 833 patients will be enrolled. PROCEDURES: Patients who have received intravenous tissue plasminogen activator are randomized to either continue with intravenous tissue plasminogen activator alone or additionally proceed to neurothrombectomy using the Solitaire device within six-hours of symptom onset.
April 2015Characterization of the NanoDot OSLD Dosimeter in CT.
PURPOSE: The extensive use of computed tomography (CT) in diagnostic procedures is accompanied by a growing need for more accurate and patient-specific dosimetry techniques. Optically stimulated luminescent dosimeters (OSLDs) offer a potential solution for patient-specific CT point-based surface dosimetry by measuring air kerma. The purpose of this work was to characterize the OSLD nanoDot for CT dosimetry, quantifying necessary correction factors, and evaluating the uncertainty of these factors. METHODS: A characterization of the Landauer OSL nanoDot (Landauer, Inc., Greenwood, IL) was conducted using both measurements and theoretical approaches in a CT environment. The effects of signal depletion, signal fading, dose linearity, and angular dependence were characterized through direct measurement for CT energies (80-140 kV) and delivered doses ranging from ~5 to >1000 mGy. Energy dependence as a function of scan parameters was evaluated using two independent approaches: direct measurement and a theoretical approach based on Burlin cavity theory and Monte Carlo simulated spectra. This beam-quality dependence was evaluated for a range of CT scanning parameters.
April 2015Complementary Radial Tagging for Improved Myocardial Tagging Contrast.
PURPOSE: To develop and evaluate complementary radial tagging (CRT) for improved myocardial tagging contrast. METHODS: We sought to develop and evaluate CRT, which aims to preserve the radial tag contrast throughout the cardiac cycle. Similar to complementary spatial modulation of magnetization, CRT acquires two sets of images with a phase shift in the tag pattern. The combination of a ramped imaging flip angle and image subtraction enhances tag contrast throughout the cardiac cycle. The proposed CRT technique uses a small table shift away from the isocenter to improve the uniformity of the radial tag pattern. We provide a mathematical solution for the optimal table shift and validate the solution in using a retrospective analysis of images from 500 patients in the Cardiac Atlas Project database.
April 2015Postischemic Hyperperfusion on Arterial Spin Labeled Perfusion MRI is Linked to Hemorrhagic Transformation in Stroke.
The purpose of this study was to investigate the relationship between hyperperfusion and hemorrhagic transformation (HT) in acute ischemic stroke (AIS). Pseudo-continuous arterial spin labeling (ASL) with background suppressed 3D GRASE was performed during routine clinical magnetic resonance imaging (MRI) on AIS patients at various time points. Arterial spin labeling cerebral blood flow (CBF) maps were visually inspected for the presence of hyperperfusion. Hemorrhagic transformation was followed during hospitalization and was graded on gradient recalled echo (GRE) scans into hemorrhagic infarction (HI) and parenchymal hematoma (PH). A total of 361 ASL scans were collected from 221 consecutive patients with middle cerebral artery stroke from May 2010 to September 2013. Hyperperfusion was more frequently detected posttreatment (odds ratio (OR)=4.8, 95% confidence interval (CI) 2.5 to 8.9, P<0.001) and with high National Institutes of Health Stroke Scale (NIHSS) scores at admission (P<0.001). There was a significant association between having hyperperfusion at any time point and HT (OR=3.5, 95% CI 2.0 to 6.3, P<0.001). There was a positive relationship between the grade of HT and time-hyperperfusion with the Spearman's rank correlation of 0.44 (P=0.003). Arterial spin labeling hyperperfusion may provide an imaging marker of HT, which may guide the management of AIS patients post tissue-type plasminogen activator (tPA) and/or endovascular treatments. Late hyperperfusion should be given more attention to prevent high-grade HT.
March 2015Representing and Extracting Lung Cancer Study Metadata: Study Objective and Study Design.
This paper describes the information retrieval step in Casama (Contextualized Semantic Maps), a project that summarizes and contextualizes current research papers on driver mutations in non-small cell lung cancer. Casama's representation of lung cancer studies aims to capture elements that will assist an end-user in retrieving studies and, importantly, judging their strength. This paper focuses on two types of study metadata: study objective and study design. 430 abstracts on EGFR and ALK mutations in lung cancer were annotated manually. Casama's support vector machine (SVM) automatically classified the abstracts by study objective with as much as 129% higher F-scores compared to PubMed's built-in filters. A second SVM classified the abstracts by epidemiological study design, suggesting strength of evidence at a more granular level than in previous work. The classification results and the top features determined by the classifiers suggest that this scheme would be generalizable to other mutations in lung cancer, as well as studies on driver mutations in other cancer domains.
March 2015Multifocality and Prostate Cancer Detection by Multiparametric Magnetic Resonance
BACKGROUND: Multiparametric magnetic resonance imaging (mp-MRI) is increasingly used in prostate cancer (CaP). Understanding the limitations of tumor detection, particularly in multifocal disease, is important in its clinical application. OBJECTIVE: To determine predictors of CaP detection by mp-MRI as confirmed by whole-mount histopathology. DESIGN, SETTING, AND PARTICIPANTS: A retrospective study was performed of 122 consecutive men who underwent mp-MRI before radical prostatectomy at a single referral academic center. A genitourinary radiologist and pathologist collectively determined concordance. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The odds of tumor detection were calculated for clinical, MRI, and histopathologic variables using a multivariate logistic regression model.
March 2015Emerging Potential of Natural Products for Targeting Mucins for Therapy Against Inflammation and Cancer.
Deregulated mucin expression is a hallmark of several inflammatory and malignant pathologies. Emerging evidence suggests that, apart from biomarkers, these deregulated mucins are functional contributors to the pathogenesis in inflammation and cancer. Both overexpression and downregulation of mucins in various organ systems is associated with pathobiology of inflammation and cancer. Restoration of mucin homeostasis has become an important goal for therapy and management of such disorders has fueled the quest for selective mucomodulators. With improved understanding of mucin regulation and mechanistic insights into their pathobiological roles, there is optimism to find selective non-toxic agents capable of modulating mucin expression and function. Recently, natural compounds derived from dietary sources have drawn attention due to their anti-inflammatory and anti-oxidant properties and low toxicity. Considerable efforts have been directed towards evaluating dietary natural products as chemopreventive and therapeutic agents; identification, characterization and synthesis of their active compounds; and improving their delivery and bioavailability. We describe the current understanding of mucin regulation, rationale for targeting mucins with natural products and discuss some natural products that modulate mucin expression and functions. We further discuss the approaches and parameters that should guide future research to identify and evaluate selective natural mucomodulators for therapy.
March 2015Catheter Ablation of Accessory Pathways Near the Coronary Sinus: Value of Defining Coronary Arterial Anatomy.
BACKGROUND: Accessory pathways can lie near or within the coronary sinus (CS). Radiofrequency catheter ablation of accessory pathways is a well-established treatment option, but this procedure can cause damage to adjacent coronary arteries. OBJECTIVE: The purpose of this study was to evaluate the anatomic relationship between the coronary arteries and the CS. METHODS: Retrospective data of patients who underwent catheter ablation of supraventricular tachycardia between June 2011 and August 2013 was reviewed. In addition, detailed analysis of coronary computed tomographic angiography (CTA) data from 50 patients was performed.
March 2015Diagnostic and Interventional Radiology for Liver Diseases.
Diseases of the liver are common and often chronic. Moreover, the mortality rate associated with chronic liver diseases remains high, despite the constant development of novel diagnostic and therapeutic modalities; therefore, numerous efforts are being made to improve imaging techniques, especially in this decade. Currently available imaging procedures allow us to ascertain the morphology, circulation, metabolism, parenchymal texture, fibrosis, and/or tumor viability in the liver. New modalities and protocols, such as magnetic resonance (MR) perfusion, MR elastography, and dual-energy computed tomography (CT), enable the potential evaluation of liver function via imaging studies. Thus, the utilization of advanced imaging techniques and contemporary interventional radiology (IR) devices has realized novel multimodality treatments for liver diseases, resulting in promising outcomes in many patients who cannot be surgically treated.
March 2015High-resolution, Whole-body Vascular Imaging with Ferumoxytol as an Alternative to Gadolinium Agents in a Pediatric Chronic Kidney Disease Cohort.
BACKGROUND: Exposure to gadolinium-based contrast agents (GBCA) in patients with chronic kidney disease (CKD) has been associated with the development of a potentially fatal disorder, nephrogenic systemic fibrosis (NSF). Although contrast-enhanced computed tomography (CT) is an alternative to magnetic resonance imaging (MRI), it carries the risk of radiation exposure and further reduction of residual renal function. Therefore we sought to assess the feasibility of ferumoxytol as an alternative to GBCA for contrast-enhanced MR angiography (MRA) in a pediatric cohort with CKD. Ferumoxytol is a parenteral iron supplement that contains ultrasmall superparamagnetic iron oxide (USPIO) and is a potent relaxivity agent for MRI. METHODS: We describe the MRI findings in ten pediatric patients who needed detailed vascular mapping. Ferumoxytol (4 mg/kg) was administered intravenously for contrast-enhanced MRA. The patients tolerated the procedure without complications.
March 2015Management of Hepatocellular Carcinoma with Portal Vein Thrombosis.
Management of hepatocellular carcinoma (HCC) with portal vein thrombosis (PVT) is complex and requires an understanding of multiple therapeutic options. PVT is present in 10%-40% of HCC at the time of diagnosis, and is an adverse prognostic factor. Management options are limited, as transplantation is generally contraindicated, and surgical resection is only rarely performed in select centers. Systemic medical therapy with sorafenib has been shown to modestly prolong survival. Transarterial chemoembolization has been performed in select cases but has shown a high incidence of complications. Emerging data on treatment of PVT with Y-90 radioembolization suggest that this modality is well-tolerated and associated with favorable overall survival. Current society guidelines do not yet specifically recommend radioembolization for patients with PVT, but this may change with the development of newer staging systems and treatment algorithms. In this comprehensive literature review, we present current and available management options with the relative advantages, disadvantages and contraindications of these treatment options with summarized data on overall survival.
March 2015Novel Technique for Characterizing Prostate Cancer Utilizing MRI Restriction Spectrum Emaging: Proof of Principle and Initial Clinical Experience with Extraprostatic Extension.
BACKGROUND: Standard magnetic resonance imaging (MRI) of the prostate lacks sensitivity in the diagnosis and staging of prostate cancer (PCa). To improve the operating characteristics of prostate MRI in the detection and characterization of PCa, we developed a novel, enhanced MRI diffusion technique using restriction spectrum imaging (RSI-MRI). METHODS: We compared the efficacy of our novel RSI-MRI technique with standard MRI for detecting extraprostatic extension (EPE) among 28 PCa patients who underwent MRI and RSI-MRI prior to radical prostatectomy, 10 with histologically proven pT3 disease. RSI cellularity maps isolating the restricted isotropic water fraction were reconstructed based on all b-values and then standardized across the sample with z-score maps. Distortion correction of the RSI maps was performed using the alternating phase-encode technique.
March 2015Optimal Flip Angle for High Contrast Balanced SSFP Cardiac Cine Imaging.
PURPOSE: To determine the optimal flip angle (FA) for cardiac cine imaging that maximizes myocardial signal and blood-myocardium contrast. METHODS: Bloch equation simulations of stationary myocardium and flowing blood with an imperfect slice profile were compared to in vivo measurements of blood and myocardium signal-to-noise ratio (SNR) and blood-myocardium contrast-to-noise ratio (CNR) in healthy subjects (N = 10) in the short-axis and four-chamber views and in patients (N = 7) in the three-chamber imaging plane.
February 2015Alvarado Score: Can it Reduce Unnecessary CT Scans for Evaluation of Acute Appendicitis?
OBJECTIVE: The objective of the study is to assess the utility of Alvarado score in the diagnosis of acute appendicitis and the utility of computed tomographic (CT) scan for evaluation of acute appendicitis when stratified by Alvarado scores. MATERIALS AND METHODS: Retrospective cohort study comprised adult patients who underwent abdominal CT for suspected acute appendicitis between January 2006 and December 2009. Two abdominal radiologists independently reviewed the CT scans; any discrepancies were resolved by a consensus review. Alvarado scores were calculated and categorized as low (0-3), equivocal (4-6), or high (7-10) probability for appendicitis. The diagnostic utility of CT scans and Alvarado score for acute appendicitis were compared with the criterion standard of combined medical chart review and pathology findings.
February 2015Correlation of Clot Imaging with Endovascular Recanalization in Internal Carotid Artery Terminus Occlusion.
BACKGROUND AND PURPOSE: In a swine stroke model we have previously demonstrated a high-intensity fluid attenuated inversion recovery (FLAIR) signal representing the erythrocyte component of the clot. We hypothesized that the intensity of the FLAIR clot signal in patients with acute stroke may predict the efficacy of recanalization by thrombectomy devices. In this study we compared the pretreatment FLAIR signal intensity of the clots in the distal internal carotid artery (ICA) and the degree of angiographic recanalization rate after mechanical thrombectomy. METHODS: 25 consecutive acute stroke patients with ICA terminus (ICA-T) occlusion diagnosed with MRI at the UCLA Medical Center between 2002 and 2013 were retrospectively reviewed. The intensity of the FLAIR clot signal at the distal ICA was blindly compared with the angiographic recanalization status (successful recanalization defined as Thrombolysis In Cerebral Infarction (TICI) score of 2b-3) and non-successful recanalization as TICI score 0-2a) after endovascular treatment. Multivariate logistic regression analysis for successful recanalization was performed.
February 2015A Novel Bicompartmental Mathematical Model of Glioblastoma Multiforme.
Glioblastoma multiforme (GBM) is the most common primary CNS neoplasm, and continues to have a dismal prognosis. A widely-used approach to the mathematical modeling of GBM involves utilizing a reaction-diffusion model of cell density as a function of space and time, which accounts for both the infiltrative nature of the tumor using a diffusion term, and the proliferation of tumor cells using a proliferation term. The current paper extends the standard models by incorporating an advection term to account for the so-called 'cell streaming' which is often seen with GBM, where some of the tumor cells seem to stream widely along the white matter pathways. The current paper introduces a bicompartmental GBM model in the form of coupled partial differential equations with a component of dispersive cells. The parameters needed for this model are explored. It is shown that this model can account for the rapid distant dispersal of GBM cells in the CNS, as well as such phenomena as multifocal gliomas with tumor foci distant from the core tumor site. The model suggests a higher percentage of tumor cells below the threshold of MRI images in comparison to the standard model. By incorporating an advection component, the proposed model is able to account for phenomena such as multicentric gliomas and rapid distant dispersion of a small fraction of tumor cells throughout the CNS, features important to the prognosis of GBM, but not easily accounted for by current models.
February 2015Native Renal Biopsy: the Perfect Storm.
We would like to thank Kriegshauser and coworkers (1) for a well written and interesting article. Even though the conclusion was somewhat expected, that higher preprocedure blood pressures increase the complication risk of native renal biopsy, what we found surprising was the magnitude of the relative risk increase that they encountered. They found that the risk of a major complication was 23 times higher for a patient with a systolic blood pressure greater than 170 mm Hg, and seven times higher for a patient with systolic blood pressure of 141–170 mm Hg, compared with normotensive patients. Previous studies have shown a range of odds ratios for systolic hypertension in native renal biopsy, ranging from no increased risk (2) to a fourfold increased risk (3), but never an odds ratio of this magnitude.
February 2015Frequency of Nonthromboembolic Imaging Abnormalities in Pregnant Women Referred for Computed Tomography Pulmonary Arteriography.
PURPOSE: The study sought to determine the frequency of nonthromboembolic imaging abnormalities in pregnant women referred for computed tomography pulmonary arteriography (CTPA). MATERIALS AND METHODS: CTPA studies on 100 consecutive pregnant women performed over a 5-year period were reviewed independently by 2 radiologists, with conflicts resolved by consensus. Age range was 18-43 years (mean 28 years). The presence or absence of pulmonary embolism and of nonthromboembolic imaging abnormalities was recorded. These were graded as A if the abnormalities were thought to provide potential alternative explanations for acute symptoms, B if findings were incidental that required clinical or radiologic follow-up, and C if the findings did not require further action.
February 2015White Matter Ischemic Changes in Hyperacute Ischemic Stroke: Voxel-Based Analysis Using Diffusion Tensor Imaging and MR Perfusion.
BACKGROUND AND PURPOSE: The purpose of this study was to evaluate changes in fractional anisotropy (FA), as measured by diffusion tensor imaging, of white matter (WM) infarction and hypoperfusion in patients with acute ischemic stroke using a quantitative voxel-based analysis. METHODS: In this prospective study, diffusion tensor imaging and dynamic susceptibility contrast perfusion sequences were acquired in 21 patients with acute ischemic stroke who presented within 6 hours of symptom onset. The coregistered FA, apparent diffusion coefficient, and dynamic susceptibility contrast time to maximum (Tmax) maps were used for voxel-based quantification using a region of interest approach in the ipsilateral affected side and in the homologous contralateral WM. The regions of WM infarction versus hypoperfusion were segmented using a threshold method. Data were analyzed by regression and ANOVA.
February 2015Genomics of Brain Tumor Imaging.
Imaging genomics combines imaging-defined phenotypes with molecular determinants of disease. Recent studies have examined the relationship between MRI-derived feature sets and gene expression in gliomas, including glioblastoma (GBM). Several groups have identified correlations between the expression of particular molecularly defined oncogenic pathways in GBM and malignant phenotypes on MRI. The combination of clinical, genetic, and imaging data has improved prognostic modeling and has identified potential therapeutic targets. Many challenges remain in fully leveraging the associations between such large datasets, but even current methodology shows promise in helping to craft individually tailored treatments to patients with brain tumors and other diseases.
February 2015Neuroimaging Abnormalities, Neurocognitive Function, and Fatigue in Patients with Hepatitis C.
OBJECTIVE: This study examined neurologic abnormalities (as measured by proton magnetic resonance spectroscopy imaging and diffusion tensor imaging), neurocognitive performance, and fatigue among a sample of adults with hepatitis C virus (HCV). We hypothesized that HCV+ individuals would demonstrate structural brain abnormalities and neurocognitive compromise consistent with frontostriatal dysfunction as well as increased fatigue compared to controls. METHOD: Participants were 76 individuals diagnosed with HCV and 20 controls who underwent a comprehensive neurocognitive evaluation and clinical assessments. A subset of the HCV+ participants (n = 29) and all controls underwent MRI.
February 2015Phase Contrast MRI with Flow Compensation View Sharing.
PURPOSE: To develop and evaluate a technique for accelerating phase contrast MRI (PC-MRI) acquisitions without significant compromise in flow quantification accuracy. METHODS: PC-MRI is commonly acquired using interleaved flow-compensated (FC) and flow-encoded (FE) echoes. We hypothesized that FC data, which represent background phase, do not change significantly over time. Therefore, we proposed to undersample the FC data and use an FC view sharing (FCVS) approach to synthesize a composite FC frame for each corresponding FE frame. FCVS was evaluated in a flow phantom and healthy volunteers and compared with a standard FC/FE PC-MRI.
January 2015The Hangman Technique: a Modified Loop Snare Technique for the Retrieval of Inferior Vena Cava Filters with Embedded Hooks.
The loop snare technique is a method for inferior vena cava (IVC) filter retrieval that creates a wire loop between the filter legs; this technique may fail in cases with an embedded hook. This report describes the hangman technique, a modified loop snare technique for filter retrieval that creates a wire loop between the filter neck and IVC wall for release of embedded filter hooks. The hangman technique was attempted in 11 cases complicated by tilt (mean tilt, 13.3 degrees ± 3.9) and an embedded hook (mean dwell time, 194.5 d) with a retrieval success rate of 81.8% (9 of 11 cases) and no associated complications.
January 2015Radiogenomics and Imaging Phenotypes in Glioblastoma: Novel Observations and Correlation with Molecular Characteristics.
Radiogenomics is a provocative new area of research based on decades of previous work examining the association between radiological and histological features. Many generalized associations have been established linking anatomical imaging traits with underlying histopathology, including associations between contrast-enhancing tumor and vascular and tumor cell proliferation, hypointensity on pre-contrast T1-weighted images and necrotic tissue, and associations between hyperintensity on T2-weighted images and edema or nonenhancing tumor. Additionally, tumor location, tumor size, composition, and descriptive features tend to show significant associations with molecular and genomic factors, likely related to the cell of origin and growth characteristics. Additionally, physiologic MRI techniques also show interesting correlations with underlying histology and genomic programs, including associations with gene expression signatures and histological subtypes. Future studies extending beyond simple radiology-histology associations are warranted in order to establish radiogenomic analyses as tools for prospectively identifying patient subtypes that may benefit from specific therapies.
January 2015Impact of 68Ga-DOTATATE PET/CT on the Management of Neuroendocrine Tumors: The Referring Physician's Perspective.
Somatostatin receptor imaging with 68Ga-DOTATATE PET/CT (DOTATATE) is increasingly used for managing patients with neuroendocrine tumors. The objective of this study was to determine referring physicians' perspectives on the impact of DOTATATE on the management of neuroendocrine tumors. METHODS: A set of 2 questionnaires (pre-PET and post-PET) was sent to the referring physicians of 100 consecutive patients with known or suspected neuroendocrine tumors, who were evaluated with DOTATATE. Questionnaires on 88 patients were returned (response rate, 88%). Referring physicians categorized the DOTATATE findings on the basis of the written PET reports as negative, positive, or equivocal for disease. The likelihood for metastatic disease was scored as low, moderate, or high. The intended management before and changes as a consequence of the PET study were indicated.
January 2015Comparison of the Quantitative CT Imaging Biomarkers of Idiopathic Pulmonary Fibrosis at Baseline and Early Change with an Interval of 7 Months.
RATIONALE AND OBJECTIVES: Median survival of patients with idiopathic pulmonary fibrosis (IPF) is 2-5 years. Sensitive imaging metrics can play a role in detecting early changes in therapeutic development. The aim of the present study was to compare known computed tomography (CT) histogram kurtosis and a classifier-based quantitative score to assess baseline severity and change over time in patients with IPF. MATERIALS AND METHODS: A total of 57 patients with at least baseline and paired follow-up scans were selected from an imaging database of standardized CT scans obtained from patients with IPF. CT histogram measurement of kurtosis and quantitative lung fibrosis (QLF) and quantitative interstitial lung disease (QILD) scores from a classification algorithm were calculated. Spearman rank correlations were used to assess associations between baseline severity and changes for all CT-derived measures compared to forced vital capacity (FVC) and carbon monoxide diffusion capacity (DLCO) (percent predicted).
January 2015Nitroxoline Induces Apoptosis and Slows Glioma Growth in vivo.
BACKGROUND: Nitroxoline is an FDA-approved antibiotic with potential antitumor activity. Here we evaluated whether nitroxoline has antiproliferative properties on glioma cell growth in vitro and in vivo using glioma cell lines and a genetically engineered PTEN/KRAS mouse glioma model. METHODS: The effect of nitroxoline treatment on U87 and/or U251 glioma cell proliferation, cell-cycle arrest, invasion, and ability to induce an apoptotic cascade was determined in vitro. Magnetic resonance imaging was used to measure glioma volumes in genetically engineered PTEN/KRAS mice prior to and after nitroxoline therapy. Induction of apoptosis by nitroxoline was evaluated at the end of treatment using terminal deoxyribonucleotidyl transferase (TDT)-mediated dUTP-digoxigenin nick end labeling (TUNEL).
January 2015Y90 Selective Internal Radiation Therapy.
Primary liver malignancies and liver metastases are affecting millions of individuals worldwide. Because of their late and advanced stage presentation, only 10% of patients can receive curative surgical treatment, including transplant or resection. Alternative treatments, such as systemic chemotherapy, ablative therapy, and chemoembolization, have been used with marginal survival benefits. Selective internal radiation therapy (SIRT), also known as radioembolization, is a compelling alternative treatment option for primary and metastatic liver malignancies with a growing body of evidence. In this article, an introduction to SIRT including background, techniques, clinical outcomes, and complications is reviewed.
January 2015Biomimetic Scaffolds Facilitate Healing of Critical-sized Segmental Mandibular Defects.
OBJECTIVE: To investigate the efficacy of biomimetic PLGA scaffolds, alone and in combination with bone morphogenic protein (BMP-2) and adipose-derived stem cells (ASCs), to heal a critical-sized segmental mandibular defect in a rat model. STUDY DESIGN: Prospective animal study. METHODS: ASCs were isolated and cultured from the inguinal fat of Lewis rat pups. Using three-dimensional printing, PLGA scaffolds were fabricated and impregnated with BMP-2 and/or ASCs. Critical-sized 5-mm segmental mandibular defects were created in adult Lewis rats and implanted with (1) blank PLGA scaffolds, (2) PLGA scaffolds with ASCs, (3) PLGA scaffolds with BMP, or (4) PLGA scaffolds with BMP and ASCs. Animals were sacrificed at 12weeks. Bone regeneration was assessed using microCT, and graded on a semi-quantitative bone formation and bone union scale.
January 2015High-field MR Imaging in Pediatric Congenital Heart Disease: Initial Results.
BACKGROUND: Comprehensive assessment of pediatric congenital heart disease (CHD) at any field strength mandates evaluation of both vascular and dynamic cardiac anatomy for which diagnostic quality contrast-enhanced magnetic resonance angiography (CEMRA) and cardiac cine are crucial. OBJECTIVE: To determine whether high-resolution (HR) CEMRA and steady-state free precession (SSFP) cine can be performed reliably at 3.0 T in children with CHD and to compare the image quality to similar techniques performed at 1.5 T. MATERIALS AND METHODS: Twenty-eight patients with a median age of 5 months and average weight 9.0 ± 7.8 kg with suspected or known CHD were evaluated at 3.0 T. SSFP cine (n = 86 series) and HR-CEMRA (n = 414 named vascular segments) were performed and images were scored for image quality and artifacts. The findings were compared to those of 28 patients with CHD of similar weight who were evaluated at 1.5 T.
January 2015Delayed Intravenous Contrast-enhanced 3D FLAIR MRI in Meniere's Disease: Correlation of Quantitative Measures of Endolymphatic Hydrops with Hearing.
OBJECTIVE: Using three-dimensional fluid-attenuated inversion recovery magnetic resonance imaging (3D-FLAIR MRI), our goal was to correlate quantifiable measures of endolymphatic hydrops (EH) with auditory function in the setting of Meniere's disease (MD). MATERIALS AND METHODS: Forty-one ears were analyzed in 21 subjects (12 ears with MD, 29 without MD). Vestibular endolymphatic space size measurements obtained with two different techniques were referenced against clinical data.
January 2015Fine Needle Elastography (FNE) Device for Biomechanically Determining Local Variations of Tissue Mechanical Properties.
Diseased tissues exhibit changes in mechanical properties and thus possess clinical diagnostic significance. We report the design and development of a Fine Needle Elastography (FNE) prototype device integrated with Fine Needle Aspiration Cytology (FNAC) needle that allows for quantitative and sensitive assessment of tissues and materials based on local variations in elastic, friction, and cutting forces on needle insertion. A piezoelectric force-sensor at the base of FNA needle measures the forces opposing needle penetration with micrometer scale resolution. Measurement precision (±5µm) and axial resolution (~20µm) of FNE device was tested using control mm size gelatin matrices and unripe pear in assessing needle penetration resistance, force heterogeneity and optimization of needle penetration velocity. Further, we demonstrated the usefulness of FNE in quantitative, biomechanical differentiation of simulated thyroid tumor nodules in an ultrasound neck phantom. Fluid or solid nodules were probed in the phantom study coupled with ultrasound guidance. Our data shows significantly higher force variations (1-D force heterogeneity; HF,a=6.5mN, HF,q=8.25mN and stiffness heterogeneity; HS,a=0.0274kN/m, HS,q=0.0395kN/m) in solid nodules compared either to fluid nodules or to regions corresponding to healthy thyroid tissue within the ultrasound phantom. The results suggest future applications of in vivo FNE biopsies based on force heterogeneity to diagnose thyroid tumors in areas where ultrasound instrumentation or access to a qualified pathologist for FNAC are unavailable, as well as an ancillary diagnostic tool in thyroid cancer management.