Daniel S. Chow

Semiautomated volumetric measurement on postcontrast MR imaging for analysis of recurrent and residual disease in glioblastoma multiforme.

BACKGROUND AND PURPOSE: A limitation in postoperative monitoring of patients with glioblastoma is the lack of objective measures to quantify residual and recurrent disease. Automated computer-assisted volumetric analysis of contrast-enhancing tissue represents a potential tool to aid the radiologist in following these patients. In this study, we hypothesize that computer-assisted volumetry will show increased precision and speed over conventional 1D and 2D techniques in assessing residual and/or recurrent tumor. MATERIALS AND METHODS: This retrospective study included patients with native glioblastomas with MR imaging performed at 24–48 hours following resection and 2–4 months postoperatively. 1D and 2D measurements were performed by 2 neuroradiologists with Certificates of Added Qualification. Volumetry was performed by using manual segmentation and computer-assisted volumetry, which combines region-based active contours and a level set approach. Tumor response was assessed by using established 1D, 2D, and volumetric standards. Manual and computer-assisted volumetry segmentation times were compared. Interobserver correlation was determined among 1D, 2D, and volumetric techniques. RESULTS: Twenty-nine patients were analyzed. Discrepancy in disease status between 1D and 2D compared with computer-assisted volumetry was 10.3% (3/29) and 17.2% (5/29), respectively. The mean time for segmentation between manual and computer-assisted volumetry techniques was 9.7 minutes and <1 minute, respectively (P < .01). Interobserver correlation was highest for volumetric measurements (0.995; 95% CI, 0.990–0.997) compared with 1D (0.826; 95% CI, 0.695–0.904) and 2D (0.905; 95% CI, 0.828–0.948) measurements. CONCLUSIONS: Computer-assisted volumetry provides a reproducible and faster volumetric assessment of enhancing tumor burden, which has implications for monitoring disease progression and quantification of tumor burden in treatment trials.

Research productivity in neurosurgery: trends in globalization, scientific focus, and funding

OBJECT While research is important for the survival, growth, and expansion of neurosurgery, little work has been done to quantify the status and trends of neurosurgical publications. The purpose of this bibliometric study was to quantitatively analyze trends in neurosurgical publications, including changes in worldwide productivity, study methodology, subspecialty topic, and funding. METHODS This was a retrospective bibliometric study using MEDLINE to record all publications between 1996 and 2009 by first authors affiliated with neurosurgical departments. Country of origin, MEDLINE-defined methodology, study topic, and funding sources (for US articles) were recorded. Linear regression was used to derive growth rates. RESULTS Total articles numbered 53,425 during the study period, with leading global contributors including the US with 16,943 articles (31.7%) and Japan with 10,802 articles (20.2%). Countries demonstrating rapid growth in productivity included China (121.9 ± 9.98%/year, p < 0.001), South Korea (50.5 ± 4.7%/year, p < 0.001), India (19.4 ± 1.8%/year, p < 0.001), and Turkey (25.3 ± 2.8%/year, p < 0.001). While general research articles, case reports, and review articles have shown steady growth since 1996, clinical trials and randomized controlled trials have declined to 2004 levels. The greatest overall subspecialty growth was seen in spine surgery. Regarding funding, relative contribution of National Institutes of Health (NIH)-funded publications decreased from 30.2% (290 of 959) to 22.5% (356 of 1229) between 1996 and 2009. CONCLUSIONS Neurosurgical publications demonstrate continued increases in productivity as well as in global expansion, although US contributions remain dominant. Two challenges that the neurosurgical community is facing include the preponderance of case reports and review articles and the relative decline in NIH funding for US neurosurgical publications, as productivity has outpaced government financial support.

Value of Gadolinium-Enhanced MRI in Detection of Acute Appendicitis in Children and Adolescents

OBJECTIVE The aim of this study was to determine both the value of gadolinium-enhanced MRI in children with suspected acute appendicitis and the best sequences for detecting acute appendicitis, to thereby decrease imaging time. MATERIALS AND METHODS This was a retrospective review of pediatric patients with suspected appendicitis who had undergone MRI at our institution between 2010 and 2011 after an indeterminate ultrasound examination. MRI examinations included T1-weighted unenhanced and contrast-enhanced, T2-weighted, and balanced steady-state free precession (SSFP) sequences in axial and coronal planes. Sequences were reviewed together and individually by five radiologists who were blinded to the final diagnosis. Radiologists were asked to score their confidence of appendicitis diagnosis using a 5-point scale. The diagnostic performance of each MR sequence was obtained by comparing the mean area under the curve (AUC) using receiver operating characteristic (ROC) analysis. RESULTS A total of 49 patients with clinically suspected appendicitis were included, of whom 16 received a diagnosis of appendicitis. The mean AUCs for reviewing all sequences together, contrast-enhanced sequences alone, T2-weighted sequences alone, and balanced SSFP alone were 0.984, 0.979, 0.944, and 0.910, respectively. No significant difference was observed between reviewing all sequences together versus contrast-enhanced sequences alone (p = 0.90) and T2-weighted sequences alone (p = 0.23). A significant difference was observed between contrast-enhanced sequences and balanced SSFP (p < 0.03). CONCLUSION Gadolinium-enhanced images and T2-weighted images are most helpful in the assessment of acute appendicitis in the pediatric population. These findings have led to protocol modifications that have reduced imaging time.

Big Data and the Future of Radiology Informatics

Rapid growth in the amount of data that is electronically recorded as part of routine clinical operations has generated great interest in the use of Big Data methodologies to address clinical and research questions. These methods can efficiently analyze and deliver insights from high-volume, high-variety, and high-growth rate datasets generated across the continuum of care, thereby forgoing the time, cost, and effort of more focused and controlled hypothesis-driven research. By virtue of an existing robust information technology infrastructure and years of archived digital data, radiology departments are particularly well positioned to take advantage of emerging Big Data techniques. In this review, we describe four areas in which Big Data is poised to have an immediate impact on radiology practice, research, and operations. In addition, we provide an overview of the Big Data adoption cycle and describe how academic radiology departments can promote Big Data development.

Aggressive resection at the infiltrative margins of glioblastoma facilitated by intraoperative fluorescein guidance

OBJECTIVE Extent of resection is an important prognostic factor in patients undergoing surgery for glioblastoma (GBM). Recent evidence suggests that intravenously administered fluorescein sodium associates with tumor tissue, facilitating safe maximal resection of GBM. In this study, the authors evaluate the safety and utility of intraoperative fluorescein guidance for the prediction of histopathological alteration both in the contrast-enhancing (CE) regions, where this relationship has been established, and into the non-CE (NCE), diffusely infiltrated margins. METHODS Thirty-two patients received fluorescein sodium (3 mg/kg) intravenously prior to resection. Fluorescence was intraoperatively visualized using a Zeiss Pentero surgical microscope equipped with a YELLOW 560 filter. Stereotactically localized biopsy specimens were acquired from CE and NCE regions based on preoperative MRI in conjunction with neuronavigation. The fluorescence intensity of these specimens was subjectively classified in real time with subsequent quantitative image analysis, histopathological evaluation of localized biopsy specimens, and radiological volumetric assessment of the extent of resection. RESULTS Bright fluorescence was observed in all GBMs and localized to the CE regions and portions of the NCE margins of the tumors, thus serving as a visual guide during resection. Gross-total resection (GTR) was achieved in 84% of the patients with an average resected volume of 95%, and this rate was higher among patients for whom GTR was the surgical goal (GTR achieved in 93.1% of patients, average resected volume of 99.7%). Intraoperative fluorescein staining correlated with histopathological alteration in both CE and NCE regions, with positive predictive values by subjective fluorescence evaluation greater than 96% in NCE regions. CONCLUSIONS Intraoperative administration of fluorescein provides an easily visualized marker for glioma pathology in both CE and NCE regions of GBM. These findings support the use of fluorescein as a microsurgical adjunct for guiding GBM resection to facilitate safe maximal removal.

Increased Rates of Authorship in Radiology Publications: A Bibliometric Analysis of 142,576 Articles Published Worldwide by Radiologists Between 1991 and 2012

UNLABELLED OBJECTIVE; There is evidence in academic medicine that the number of authors per paper has increased over time. The goal of this study was to quantitatively analyze authorship trends in the field of radiology over 20 years. MATERIALS AND METHODS A search of the National Library of Medicine MEDLINE database was conducted to identify articles published by radiology departments between 1991 and 2012. Country of origin, article study design, and journal impact factor were recorded. The increase in number of authors per paper was assessed by linear and nonlinear regression. Pearson correlation was used to assess the relation between journal impact factor and number of authors. RESULTS A total of 142,576 articles and 699,257 authors were identified during the study period. The mean number of authors per paper displayed linear growth from 3.9 to 5.7 (p < 0.0001). The proportion of single authors declined from 11% in 1991 to 4.4% in 2012. The number of clinical trials increased in a linear pattern, review articles in an exponential pattern, and case reports in a logistic pattern (p < 0.0001 for each). Countries with the highest number of authors per paper were Japan, Italy, and Germany. The number of articles funded by the U.S. National Institutes of Health (NIH) displayed exponential growth and of non-NIH-funded articles displayed linear growth (p < 0.0001 for each). A negligible relation was observed between journal impact factor and number of authors (Pearson r = 0.1066). CONCLUSION Radiology has had a steady increase in mean number of authors per paper since the early 1990s that has varied by study design. The increase is probably multi-factorial and includes components of author inflation and increasing complexity of research. Findings support the need for reemphasis of authorship criteria to preserve authorship value and accountability.

Prevalence and timing of bend relief disconnection in patients supported by the late version HeartMate II left ventricular assist device

BACKGROUND On April 4, 2012, the U.S. Food and Drug Administration issued a Class 1R recall of the HeartMate II (Thoratec Corporation, Pleasanton, CA) left ventricular assist device (LVAD) due to spontaneous detachment of the bend relief from its intended position in patients implanted with the most recent version of the HM II. This study examined the incidence and timing of outflow graft bend relief disconnection in patients implanted with the HM II LVAD. METHODS All patients supported with the modified version of the HM II LVAD were asked to report for dedicated abdominal X-ray imaging to assess the position of the bend relief. Also performed was a retrospective review of X-ray images of all patients who had previously been supported with this version but had since received a transplant, undergone LVAD explant, or died. RESULTS Between March 9, 2011, and April 9, 2012, 59 patients underwent primary implant with the modified version HM II. Follow up X-ray images were available for 56 patients (95%). The bend relief was found fully disconnected in 6 of 56 (11%) and partially disconnected in 13 (23%). Two of 6 patients (33%) with full bend relief disconnection and 1 of 13 of the initially partially disconnected patients (7.7%) required urgent surgical intervention due to symptoms of hemolysis and/or heart failure. CONCLUSIONS Bend relief disconnection is common and may be observed immediately after implant but may also develop over time. Full bend relief disconnect may present with hemolysis and/or heart failure symptoms and often requires surgical revision. Surveillance abdominal X-ray imaging should be performed routinely on all patients who were implanted with the modified version HM II.

Interventional Oncology Research in the United States: Slowing Growth, Limited Focus, and a Low Level of Funding

PURPOSE To establish the characteristics of published interventional oncology (IO) research, including the volume, growth, geographic distribution, type of research, and funding patterns, and to determine how IO research compares with overall radiology research. MATERIALS AND METHODS This retrospective bibliometric analysis of public data was exempt from Institutional Review Board approval. IO articles published between 1996 and 2008 were identified in the National Library of Medicine MEDLINE database. Country of origin, article methodology, study topic, and source of funding were recorded. Growth was analyzed by using linear and nonlinear regression. RESULTS Total journal articles numbered 3801, including 847 (22.3%) from the United States, 722 (19.0%) from Japan, and 390 (10.3%) from China. World publications grew with a sigmoid (logistic) pattern (predicted maximum of 586.8 articles per year, P < .001). The United States and China also had logistic and slowing growth (maximums of 111.0 and 48.1 articles per year, respectively; both P < .001). Growth was linear in Japan (growth of 3.0 articles per year, P < .001) and exponential and accelerating in Germany, Italy, South Korea, France, and the United Kingdom. The United States produced 187 (36.9%) review articles but only 52 (13.1%) clinical trials. Japan (75, 18.8%) and China (71, 17.8%) both produced more clinical trials than other countries. U.S. IO articles were less likely than general radiology articles to receive funding from government (12.5% vs 23.7%) and nongovernment (15.0% vs 17.0%) sources. Liver cancer articles constituted 2388 (62.8%) of all IO articles. CONCLUSION IO research is slowing in the United States but growing elsewhere. Japan and China are leaders in clinical trial research. U.S. IO research receives less funding than does overall radiology research. IO research focuses primarily on liver cancer.

Intermediate outcomes and predictors of efficacy in the radiofrequency ablation of 100 pathologically proven renal cell carcinomas.

PURPOSE To determine oncologic outcomes and predictors of primary efficacy, including RENAL nephrometry scores (radius, exophytic/endophytic properties, nearness of tumor to collecting system or sinus, anterior/posterior, location relative to polar lines), after percutaneous radiofrequency (RF) ablation of proven renal cell carcinoma (RCC). MATERIALS AND METHODS Patients who underwent percutaneous computed tomography- and ultrasound-guided RF ablation for histologically proven RCC from 2004 to 2011 were evaluated. Clinical data, pathologic findings, technical details, and outcomes were reviewed. Univariate and multivariate logistic regression analysis was performed to determine predictors of primary technique effectiveness and complications. Local tumor progression-free, metastasis-free, and overall survival were calculated. One hundred RCC lesions underwent 115 RF ablation sessions in 84 patients. Median follow-up was 24 months (mean, 27 mo; range, 1-106 mo). RESULTS Efficacy of RF ablation was defined per International Working Group of Image-Guided Tumor Ablation criteria. Total, primary, and secondary technique effectiveness rates were 95% (95 of 100), 86% (86 of 100), and 9% (nine of 100), respectively. Primary efficacy was associated with size (P < .001), proximity to collecting system (P = .001), RENAL nephrometry score (P < .001), and number of ablation zones (P < .001). Complications occurred in 13% of patients, without procedure-related deaths. The median 2.1-year local progression-free, metastasis-free, disease-specific, and overall survival rates were 86%, 98.7%, 100%, and 97.6%, respectively. CONCLUSIONS Percutaneous image-guided RF ablation for RCC provides excellent intermediate oncologic control. Location, size, proximity to the collecting system, low RENAL nephrometry score, and number of ablation zones predict primary efficacy.

Glioblastoma Induces Vascular Dysregulation in Nonenhancing Peritumoral Regions in Humans

OBJECTIVE Glioblastoma is an invasive primary brain malignancy that typically infiltrates the surrounding tissue with malignant cells. It disrupts cerebral blood flow through a variety of biomechanical and biochemical mechanisms. Thus, neuroimaging focused on identifying regions of vascular dysregulation may reveal a marker of tumor spread. The purpose of this study was to use blood oxygenation level-dependent (BOLD) functional MRI (fMRI) to compare the temporal dynamics of the enhancing portion of a tumor with those of brain regions without apparent tumors. MATERIALS AND METHODS Patients with pathologically proven glioblastoma underwent preoperative resting-state BOLD fMRI, T1-weighted contrast-enhanced MRI, and FLAIR MRI. The contralesional control hemisphere, contrast-enhancing tumor, and peritu-moral edema were segmented by use of structural images and were used to extract the time series of these respective regions. The parameter estimates (beta values) for the two regressors and resulting z-statistic images were used as a metric to compare the similarity of the tumor dynamics to those of other brain regions. RESULTS The time course of the contrast-enhancing tumor was significantly different from that of the rest of the brain (p < 0.05). Similarly, the control signal intensity was significantly different from the tumor signal intensity (p < 0.05). Notably, the temporal dynamics in the peritumoral edema, which did not contain enhancing tumor, were most similar to the those of enhancing tumor than to those of control regions. CONCLUSION The findings show that the disruption in vascular regulation induced by a glioblastoma can be detected with BOLD fMRI and that the spatial distribution of these disruptions is localized to the immediate vicinity of the tumor and peritumoral edema.