Karen Buch

Using texture analyses of contrast enhanced CT to assess hepatic fibrosis.

PURPOSE To determine the ability of texture analyses of contrast-enhanced CT images for distinguishing between varying degrees of hepatic fibrosis in patients with chronic liver disease using histopathology as the reference standard. MATERIALS AND METHODS Following IRB approval, 83 patients who underwent contrast enhanced 64-MDCT of the abdomen and pelvis in the portal venous phase between 12/2005 and 01/2013 and who had a liver biopsy within 6 months of the CT were included. An in-house developed, MATLAB-based texture analysis program was employed to extract 41 texture features from each of 5 axial segmented volumes of liver. Using the Ishak fibrosis staging scale, histopathologic grades of hepatic fibrosis were correlated with texture parameters after stratifying patients into three analysis groups, comparing Ishak scales 0-2 with 3-6, 0-3 with 4-6, and 0-4 with 5-6. To assess the utility of texture features, receiver operating characteristic (ROC) curves were constructed and the area under the curve (AUC) was used to determine the performance of each feature in distinguishing between normal/low and higher grades of hepatic fibrosis. RESULTS A total of 19 different texture features with 7 histogram features, one grey level co-occurrence matrix, 6 gray level run length, 1 Laws feature, and 4 gray level gradient matrix demonstrated statistically significant differences for discriminating between fibrosis groupings. The highest AUC values fell in the range of fair performance for distinguishing between different fibrosis groupings. CONCLUSION These findings suggest that texture-based analyses of contrast-enhanced CT images offer a potential avenue toward the non-invasive assessment of liver fibrosis.

Using Texture Analysis to Determine Human Papillomavirus Status of Oropharyngeal Squamous Cell Carcinomas on CT

BACKGROUND AND PURPOSE: Human papillomavirus–associated oropharyngeal squamous cell carcinoma is increasing in prevalence and typically occurs in younger patients than human papillomavirus–negative squamous cell carcinoma. While imaging features of human papillomavirus–positive versus human papillomavirus–negative squamous cell carcinoma nodal metastases have been described, characteristics distinguishing human papillomavirus–positive from human papillomavirus–negative primary squamous cell carcinomas have not been well established. The purpose of this project was to evaluate the use of texture features to distinguish human papillomavirus–positive and human papillomavirus–negative primary oropharyngeal squamous cell carcinoma. MATERIALS AND METHODS: Following institutional review board approval, 40 patients with primary oropharyngeal squamous cell carcinoma and known human papillomavirus status who underwent contrast-enhanced CT between December 2009 and October 2013 were included in this study. Segmentation of the primary lesion was manually performed with a semiautomated graphical-user interface. Following segmentation, an in-house-developed texture analysis program extracted 42 texture features from each segmented volume. A t test was used to evaluate differences in texture parameters between human papillomavirus–positive and human papillomavirus–negative squamous cell carcinomas. RESULTS: Of the 40 included patients, 29 had human papillomavirus–positive oropharyngeal squamous cell carcinoma and 11 had human papillomavirus–negative oropharyngeal squamous cell carcinoma. Significant differences were seen in the histogram parameters median (P = .006) and entropy (P = .016) and squamous cell carcinoma entropy (P = .043). CONCLUSIONS: There are statistically significant differences in some texture features between human papillomavirus–positive and human papillomavirus–negative oropharyngeal tumors. Texture analysis may be considered an adjunct to the evaluation of human papillomavirus status and characterization of squamous cell carcinoma.

Quantifying liver fibrosis through the application of texture analysis to diffusion weighted imaging

The purpose of this study was to evaluate the potential utility of texture analysis of parametric apparent diffusion coefficient (ADC) maps in quantifying hepatic fibrosis. To this end, using ex vivo murine liver tissues from a dietary model of hepatic fibrosis, an array of texture analysis techniques, including histogram-based, gray-level co-occurrence matrix-based, and gray-level run-length-based features, was used to evaluate correlations with liver fibrosis. Moderate to very strong correlation between several of the texture-based features and both subjective as well as digital image analysis-based assessments of hepatic fibrosis was demonstrated. This rigorous study of texture analysis applied to parametric ADC maps in a liver fibrosis model study demonstrates and validates the potential utility of texture-based features for the noninvasive, quantitative assessment of hepatic fibrosis.

Difference Between HPV-Positive and HPV-Negative Non-Oropharyngeal Head and Neck Cancer: Texture Analysis Features on CT.

Objective To identify the specific texture parameter that shows significant differences between human papillomavirus (HPV)–positive (HPV+) and HPV-negative (HPV-) non-oropharyngeal carcinoma (non-OPC) using texture analysis. Methods Forty-six patients of non-OPC patients (oral cavity, larynx, and hypopharynx) with known HPV status, who underwent contrast-enhanced computed tomography for initial staging, were retrospectively reviewed. Segmentations of the primary lesion were manually performed, and an in-house developed texture analysis program extracted 42 texture features from each segmented volume. A t test was used to evaluate differences between HPV+ and HPV- non-OPCs (P < 0.05). Results Sixteen texture parameters, including 5 histogram features (P ⩽ 0.03), 3 gray-level co-occurrence matrix features (P ⩽ 0.02), 1 gray-level run-length feature (P = 0.009), 2 gray-level gradient matrix features (P ⩽ 0.02), and 5 Law features (P ⩽ 0.04), showed significant differences. Conclusions Texture analysis demonstrated significant differences between HPV+ and HPV- non-OPCs on computed tomography images, which may have a potential to prove morphologic feature differences among HPV-related tumors.

Global and Regional Brain Assessment with Quantitative MR Imaging in Patients with Prior Exposure to Linear Gadolinium-based Contrast Agents

Purpose To assess the association of global and regional brain relaxation times in patients with prior exposure to linear gadolinium-based contrast agents (GBCAs). Materials and Methods The institutional review board approved this cross-sectional study. Thirty-five patients (nine who had received GBCA gadopentetate dimeglumine injections previously [one to eight times] and 26 patients who did not) who underwent brain magnetic resonance (MR) imaging with a mixed fast spin-echo pulse sequence were assessed. The whole brain was segmented according to white and gray matter by using a dual-clustering algorithm. In addition, regions of interest were measured in the globus pallidus, dentate nucleus, thalamus, and pons. The Mann-Whitney U test was used to assess the difference between groups. Multiple regression analysis was performed to assess the association of T1 and T2 with prior GBCA exposure. Results T1 values of gray matter were significantly shorter for patients with than for patients without prior GBCA exposure (P = .022). T1 of the gray matter of the whole brain (P < .001), globus pallidus (P = .002), dentate nucleus (P = .046), and thalamus (P = .026) and T2 of the whole brain (P = .004), dentate nucleus (P = .023), and thalamus (P = .002) showed a significant correlation with the accumulated dose of previous GBCA administration. There was no significant correlation between T1 and the accumulated dose of previous GBCA injections in the white matter (P = .187). Conclusion Global and regional quantitative assessments of T1 and T2 demonstrated an association with prior GBCA exposure, especially for gray matter structures. The results of this study confirm previous research findings that there is gadolinium deposition in wider distribution throughout the brain.

Utility of texture analysis for quantifying hepatic fibrosis on proton density MRI

To evaluate the potential utility of texture analysis of proton density maps for quantifying hepatic fibrosis in a murine model of hepatic fibrosis.

Value of Imaging Part I: Perspectives for the Academic Radiologist.

With payers and policymakers increasingly scrutinizing the value of medical imaging, opportunities abound for radiologists and radiology health services researchers to meaningfully and rigorously demonstrate value. Part one of this two-part series on the value of imaging explores the concept of value in health care from the perspective of multiple stakeholders and discusses the opportunities and challenges for radiologists and health service researchers to demonstrate value. The current absence of meaningful national value metrics also presents an opportunity for radiologists to take the lead on the discussions of these metrics that may serve as the basis for future value-based payments. As both practitioners and investigators, radiologists should consider the perspectives of multiple stakeholders in all they do-interdisciplinary support and cooperation are essential to the success of value-focused imaging research and initiatives that improve patient outcomes. Radiology departments that align their cultures, infrastructures, and incentives to support these initiatives will greatly increase their chances of being successful in these endeavors.

Head and neck injuries from the Boston Marathon bombing at four hospitals

The aim of this study was to evaluate the imaging findings of head and neck injuries in patients from the Boston Marathon bombing. A total of 115 patients from the Boston Marathon bombing presenting to four hospitals who underwent imaging to evaluate for head and neck injuries were included in the study. Twelve patients with positive findings on radiography or cross-sectional imaging were included in the final analysis. The radiographic, computed tomography (CT), and magnetic resonance (MR) imaging features of these patients were evaluated for the presence of shrapnel and morphological abnormality. Head and neck injuries were seen in 12 out of 115 patients presenting to the four hospitals. There were secondary blast injuries to the head and neck in eight patients, indicated by the presence of shrapnel on imaging. In the four patients without shrapnel, there were two with subgaleal hematomas, one with facial contusion and one with mastoid injury. There were two patients with subarachnoid hemorrhage, one with brain contusion, one with cerebral laceration, and one with globe rupture. There was frontal bone, nasal bone, and orbital wall fracture in one patient each. Imaging identified 26 shrapnel fragments, 21 of which were ball bearings. Injuries to the head and neck region identified on imaging from the Boston Marathon bombing were not common. The injuries seen were predominantly secondary blast injuries from shrapnel, and did not result in calvarial penetration of the shrapnel fragments.

Nasopharyngeal cystic lesions: Tornwaldt and mucous retention cysts of the nasopharynx: findings on MR imaging.

Objective Nasopharyngeal cystic lesions are commonly encountered on magnetic resonance imaging with significantly overlapped imaging characteristics. The purpose of this study was to determine the prevalence and distinguishing imaging features of cystic lesions in the nasopharynx in the largest patient series to date. Methods After institutional review board approval, consecutive head magnetic resonance images of 3000 patients performed at 1.5 T between June 2010 and April 2011 were retrospectively reviewed for cystic nasopharyngeal lesions. Location, size, and signal characteristic of cystic lesions were recorded. Electronic medical records were reviewed for patient demographics, symptoms, and underlying conditions. Results Among 3000 patients, 6% had Tornwaldt cysts (peak prevalence, 51–60 years old) and 10% had mucous retention cysts (peak prevalence, 41–50 years old). A significant correlation between human immunodeficiency virus infection and mucous retention cysts was observed (P < 0.001). Conclusions The prevalence of Tornwaldt cysts was slightly higher than previously described in the literature. Additionally, younger and older patients had the lowest prevalence of Tornwaldt cyst, suggesting these lesions are acquired and subsequently involute with time. A significant correlation was observed between human immunodeficiency virus infection and mucous retention cysts.

Variability in the Cross-Sectional Area and Narrowing of the Internal Jugular Vein in Patients Without Multiple Sclerosis

OBJECTIVE Chronic cerebrospinal vascular insufficiency is a proposed condition of intraluminal stenosis of the internal jugular vein (IJV) that impedes venous flow from the brain. Calculations of IJV stenosis are vague and described in veins with at least a 50% reduction in IJV caliber at a specific level. The purpose of this study was to assess normal changes in anatomic caliber of the course of the IJV in a generalized population. MATERIALS AND METHODS Images from 500 consecutive contrast-enhanced neck CT studies performed in January-July 2011 were reviewed. Cross-sectional areas of the IJV were calculated at the jugular foramen, C1-C7 levels, and jugular angles bilaterally. Patients were excluded if they had severely motion-limited studies; limited clinical data; a history of multiple sclerosis, neck mass, or neck dissection; or known IJV occlusion. Normalized IJV cross-sectional areas at each level were compared with an averaged normalized cross-sectional area from all patients at each level. RESULTS Greater than 50% narrowing compared with a normalized average was found in 133 of 363 patients (36.6%) and was seen at all IJV levels. In 36.1% of patients this narrowing occurred at the C1 level. Most of the areas of narrowing greater than 50% occurred above the C4 level. CONCLUSION The IJV has marked variability in its course in the neck. Areas of narrowing greater than 50% occur most commonly in the upper cervical and skull base regions. Given the normal anatomic variations in IJV caliber, caution should be used when making the diagnosis of and treating IJV stenosis.