Richard D. White

CT Gray-Level Texture Analysis as a Quantitative Imaging Biomarker of Epidermal Growth Factor Receptor Mutation Status in Adenocarcinoma of the Lung

OBJECTIVE The purpose of this study was to investigate the radiogenomic correlation between CT gray-level texture features and epidermal growth factor receptor (EGFR) mutation status in adenocarcinoma of the lung. MATERIALS AND METHODS This retrospective study included 25 patients with exon 19 short inframe deletion (exon 19) and 21 patients with exon 21 L858R point (exon 21) EGFR mutations among 125 patients with EGFR mutant adenocarcinoma of the lung. The randomly formed control group consisted of 20 patients selected from 126 patients with EGFR mutation-negative (wild-type) adenocarcinomas. Five gray-level texture features (contrast, correlation, inverse difference moment, angular second moment, and entropy) were analyzed. RESULTS Contrast differentiated both exon 19 (p = 0.00027) and exon 21 (p = 0.00001) mutants from the wild type. Wild-type adenocarcinomas had high scores for contrast (mean, 1598.547) compared with EGFR mutants (mean, 679.463). Correlation differentiated both exon 19 (p = 0.017) and exon 21 (p = 0.0015) mutants from wild-type adenocarcinomas. Inverse difference moment differentiated exon 19 mutants from exon 21 mutants (p = 0.019) and both exon 19 (p = 0.044) and exon 21 (p = 0.00001) mutants from wild-type adenocarcinomas. Angular second moment and entropy were not associated with statistically significant differences between mutation statuses. CONCLUSION Contrast, correlation, and inverse difference moment texture features correlate with EGFR mutation status in adenocarcinoma of the lung. Further investigation with larger prospective studies is needed to validate the role of CT gray-level texture analysis as a quantitative imaging biomarker.

Rapid acquisition technique for MR elastography of the liver.

Magnetic resonance elastography (MRE) of the liver is a novel noninvasive clinical diagnostic tool to stage fibrosis based on measured stiffness. The purpose of this study is to design, evaluate and validate a rapid MRE acquisition technique for noninvasively quantitating liver stiffness which reduces by half the scan time, thereby decreasing image registration errors between four MRE phase offsets. In vivo liver MRE was performed on 16 healthy volunteers and 14 patients with biopsy-proven liver fibrosis using the standard clinical gradient recalled echo (GRE) MRE sequence (MREs) and a developed rapid GRE MRE sequence (MREr) to obtain the mean stiffness in an axial slice. The mean stiffness values obtained from the entire group using MREs and MREr were 2.72±0.85 kPa and 2.7±0.85 kPa, respectively, representing an insignificant difference. A linear correlation of R(2)=0.99 was determined between stiffness values obtained using MREs and MREr. Therefore, we can conclude that MREr can replace MREs, which reduces the scan time to half of that of the current standard acquisition (MREs), which will facilitate MRE imaging in patients with inability to hold their breath for long periods.

Radiology Report Turnaround Time: Effect on Resident Education

RATIONALE AND OBJECTIVES To compare resident workload from Emergency Department (ED) studies before and after the implementation of a required 1-hour report turnaround time (TAT) and to assess resident and faculty perception of TAT on resident education. MATERIALS AND METHODS Resident study volume will be compared for 3 years before and 1 year after the implementation of a required 1-hour TAT. Changes to resident workload will be compared among the different radiology divisions (body, muscuolskeletal (MSK), chest, and neuro), as well as during different shifts (daytime and overnight). Residents and faculty at two Midwest institutions, both of which have a required report TAT, will be invited to participate in an online survey to query the perceived effect on resident education by implementation of this requirement. A P < .05 was considered statistically significant. RESULTS A significant decrease in resident involvement in ED studies was noted in the MSK, chest, and neuro sections with average involvement of the 3 years before the 1-hour TAT of 89%, 88%, and 82%, respectively, which decreased to 66%, 68%, and 51% after the 1-hour TAT requirement (P < .05). The resident involvement in ED studies only mildly decreased in the body section from an average before the 1-hour TAT of 87% to 80% after the 1-hour TAT requirement (P < .1). There was an overall significant decrease in resident ED study involvement during the daytime (P = .01) but not after hours during resident call (P = .1). Seventy percent of residents (43 of 61) and 55% of faculty (63 of 114) responded to our surveys. Overall, residents felt their education from ED studies during the daytime and overnight were good. However, residents who were present both before and after the implementation of a required TAT felt their education had been significantly negatively affected. Faculty surveyed thought that the required TAT negatively affected their ability to teach and decreased the quality of resident education. CONCLUSIONS Residents are exposed to fewer ED studies after the implementation of a required 1-hour TAT. Overall, the current residents do not feel this decreased exposure to Emergency room studies affects their education. However, residents in training before and after this requirement feel their education has been significantly affected. Faculty perceives that the required TAT negatively affects their ability to teach, as well as the quality of resident education.

Quantification and comparison of 4D-flow MRI-derived wall shear stress and MRE-derived wall stiffness of the abdominal aorta.

Aortic wall shear stress (WSSFlow) alters endothelial function, which in‐turn changes aortic wall stiffness leading to remodeling in different disease states. Therefore, the aims of this study are to determine normal physiologic correlations between: (1) Magnetic Resonance Elastography (MRE)‐derived aortic wall stiffness (WSMRE) and WSSFlow; (2) WSMRE and mean velocity; (3) WSMRE and pulse wave velocity (PWV);( 4) WSMRE and mean peak flow; and (5) WSMRE, WSSFlow and age using MRE and 4D‐flow MRI in the abdominal aorta in healthy human subjects.

Radiology and Enterprise Medical Imaging Extensions (REMIX)

Radiology and Enterprise Medical Imaging Extensions (REMIX) is a platform originally designed to both support the medical imaging-driven clinical and clinical research operational needs of Department of Radiology of The Ohio State University Wexner Medical Center. REMIX accommodates the storage and handling of “big imaging data,” as needed for large multi-disciplinary cancer-focused programs. The evolving REMIX platform contains an array of integrated tools/software packages for the following: (1) server and storage management; (2) image reconstruction; (3) digital pathology; (4) de-identification; (5) business intelligence; (6) texture analysis; and (7) artificial intelligence. These capabilities, along with documentation and guidance, explaining how to interact with a commercial system (e.g., PACS, EHR, commercial database) that currently exists in clinical environments, are to be made freely available.

In vivo quantification of aortic stiffness using MR elastography in hypertensive porcine model

Aortic stiffness plays an important role in evaluating and predicting the progression of systemic arterial hypertension (SAH). The aim of this study is to determine the stiffness of aortic wall using MR elastography (MRE) in a hypertensive porcine model and compare it against invasive aortic pressure measurements.

Diffusion tensor imaging of formalin fixed infarcted porcine hearts: a comparison between 3T and 1.5T

BackgroundDiffusion Tensor Imaging (DTI) quantifies the amount ofanisotropic diffusion exhibited by biological tissues. Pro-cessing DTI images allow a 3D visualization of the fiberarchitecture by tracking the fiber trajectories within thetissue. Experimental evidence has shown that the myocar-dium undergoes remodeling as myocardial infarction pro-gresses over time[1]. The aim of this study is to investigateand compare the fiber architecture in an infarcted porcineheart using DTI at 1.5T and 3T, to analyze the effect ofhigh field magnets in imaging.MethodsEx-vivo DTI was performed on an infracted pig heart on1.5T (Avanto, Siemens Hea lthcare, Germany) and 3T(Tim Trio, Siemens Healthcare, Germany) MRI scan-ners. Infarcts were created in the apex region (Fig 1) byoccluding the left ante rior descending coronary artery.After 22 days, the hearts were dissected and formalinfixed for 6 months. A diffusion-weighted echo planarimaging sequence was used to acquire multi-slice shortaxis views covering the ventric les in the excised heart.Imaging parameters included: diffusion encoding direc-tions=256; TE=90ms; TR=7000(1.5T), 6600(3T) ms; slicethickness=2mm; matrix=128x128; FOV=256x256mm2;b-values=0,1000s/mm2; slices=37(1 .5T), 42(3T); isotro-pic resolution of 2x2x2mm. The images were masked tosegment the left ventricular myocardium (LVM).Explore DTI [2], was used to obtain a tensor map andtrack the fibers using a deterministic algorithm. For thisanalysis, fractional ani sotropy (FA) and the anglebetween the longest eigenvectors (V1) of the twosuccessive voxels were set to 0.2 and 45 degrees respec-tively. The lower limit of the length of the fibers wasvaried from 2mm to 30mm to see the correspondingchange in fiber tracts near the infracted region of theLVM obtained from both 1.5T and 3T scanners.ResultsFig 1 shows the magnitude image displaying the infarctwith thin myocardial wall. Fig 2 displays 3D visualizationof the fiber tracts in the LVM. In Fig 2 the upper rowand the lower row displays data from 3T and 1.5T scan-ners respectively. From left to right the lower limit of thefiber length was varied in the analysis to track the short

Diffusion tensor imaging of formalin fixed infarcted porcine hearts

Background Diffusion is the random motion exhibited by molecules as a result of thermal agitation. In biological tissues the random motion of water molecules is anisotropic since they are restricted by the tissue structure. The application of diffusion tensor imaging (DTI) makes it possible to quantify the amount of diffusion in tissues. Further processing allows a 3D visualization of the fiber architecture by tracking the fiber trajectories within a tissue. Experimental evidence has shown that fiber architecture in the myocardium changes with the onset of myocardial infarction [1]. Furthermore, the myocardium undergoes remodeling as the infarction progresses over time. The aim of this study is to evaluate the remodeling of the fiber architecture in an infarcted porcine heart. Methods

MR elastography as a method to estimate aortic stiffness and its comparison against MR based pulse wave velocity measurement.

Background Arterial (aortic) stiffness is a well-recognized pathophysiological change that plays a significant role in the determination of risk factors for various cardiovascular diseases [1]. Measurement of arterial stiffness using pulse wave velocity (PWV) is the gold standard among non-invasive modalities. Recently, a novel non-invasive MRI based technique known as magnetic resonance elastography (MRE) was developed to determine the stiffness of the aorta[2]. The aim of the study is to compare the abdominal aortic stiffness obtained using MRI based PWV stiffness measurements against MRE based stiffness measurements.

ACR Appropriateness Criteria® Dyspnea—Suspected Cardiac Origin

This article discusses imaging guidelines for five dyspnea variants: (1) dyspnea due to heart failure, ischemia not excluded; (2) dyspnea due to suspected nonischemic heart failure, ischemia excluded; (3) dyspnea due to suspected valvular heart disease, ischemia excluded; (4) dyspnea due to suspected cardiac arrhythmia, ischemia excluded; and (5) dyspnea due to suspected pericardial disease, ischemia excluded. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.