Papers

2019
Li C, Dhyani M, Bhan AK, Grajo JR, Pratt DS, Gee MS, Samir AE. Diagnostic Performance of Shear Wave Elastography in Patients With Autoimmune Liver Disease. J Ultrasound Med. 2019;38 (1) :103-111.Abstract
OBJECTIVES: To assess performance of shear wave elastography for evaluation of fibrosis and the histologic stage in patients with autoimmune liver disease (ALD) and to validate previously established advanced fibrosis cutoff values in this cohort. METHODS: Shear wave elastography was performed on patients with ALD with an Aixplorer ultrasound system (SuperSonic Imagine, Aix-en-Provence, France) using an SC6-1 transducer. The median estimated tissue Young modulus was calculated from sets of 8 to 10 elastograms. A blinded, subspecialty-trained pathologist reviewed biopsy specimens. The METAVIR classification was used to stage liver fibrosis and necroinflammation. Steatosis was graded from 0 to 4+. The Kendall τ-b correlation test was performed to identify the correlation between the estimated tissue Young modulus and fibrosis, steatosis, and the necroinflammatory score. The Spearman correlation test was performed to identify the correlation between the estimated tissue Young modulus and clinical data. The diagnostic performance of shear wave elastography for differentiating METAVIR stage F2 or higher from F0 and F1 fibrosis was evaluated by a receiver operating characteristic (ROC) curve analysis. RESULTS: Fifty-one patients with ALD were analyzed. The estimated tissue Young modulus was positively correlated with the fibrosis stage and necroinflammation score (r = 0.386; P < .001; r = 0.338; P = .002, respectively) but not steatosis (r = -0.091; P = .527). Serum aspartate aminotransferase, alanine aminotransferase, and total bilirubin values were positively correlated with the estimated tissue Young modulus (r = 0.501; P < .001; r = 0.44; P = .001; r = 0.291; P = .038). The serum albumin value was negatively correlated (r = -0.309; P = .033). The area under the ROC curve was 0.781 (95% confidence interval, 0.641-0.921) for distinguishing F2 or greater fibrosis from F0 and F1 fibrosis. Based on the ROC curve, an optimal cutoff value of 9.15 kPa was identified (sensitivity, 83.3%; specificity, 72.7%). CONCLUSIONS: Shear wave elastography is a novel noninvasive adjunct to liver biopsy in evaluation and staging of patients with ALD, showing the potential for serial evaluations of disease progression and treatment responses.
Duan Y, Xiang F, Li Q, Li K, Grajo JR, Samir AE. Predictive Value of Duplex Ultrasound for Significant In-Stent Restenosis after Percutaneous Transluminal Renal Artery Stent Placement: A Propensity Score Matching Analysis. Ultrasound Med Biol. 2019.Abstract
To evaluate the value of pre-stenting and early post-stenting (<1 mo) duplex ultrasound parameters in predicting significant in-stent restenosis (ISR), we matched significant ISR patients 1:1 with controls without ISR in pre-stenting and early post-stenting (<1 mo) periods, respectively, using propensity score matching. Duplex ultrasound parameters, such as renal length difference between non-lesion side and lesion side within patient, trans-lesion peak systolic velocity and renal aortic ratio, were compared between cases and controls, and the area under the receiver operating characteristic curve (AUROC) was charted to predict ISR. After propensity score matching, 28 cases were matched in the pre-stenting period and 16 cases in the early post-stenting time period. Pre-stenting renal length difference, early post-stenting peak systolic velocity and renal aortic ratio showed significant differences in case-control comparisons. Early post-stenting peak systolic velocity (AUROC: 0.826, cutoff: 141 cm/s) and renal aortic ratio (AUROC: 0.770, cutoff: 1.75) performed well in predicting significant ISR and may serve as non-invasive markers in ISR surveillance.
Li Q, Lin X, Zhang X, Samir AE, Arellano RS. Imaging-Related Risk Factors for Bleeding Complications of US-Guided Native Renal Biopsy: A Propensity Score Matching Analysis. J Vasc Interv Radiol. 2019;30 (1) :87-94.Abstract
PURPOSE: To evaluate imaging-related hemorrhagic risk factors for ultrasound (US)-guided native kidney biopsy. MATERIALS AND METHODS: A retrospective review was conducted of adult patients who underwent US-guided native kidney biopsy at a single center between January 2006 and March 2016 and identified 37 of 551 patients (6.72%) with postbiopsy bleeding complications, including 11 major complications (2.00%; n = 11) and 26 minor complications (4.72%; n = 26). Ten patients with major complications and 20 with minor complications were matched with 20 control subjects each by propensity score matching based on age, needle size, number of cores, blood pressure, partial thromboplastin time, prothrombin time, platelet count, and estimated glomerular filtration rate. RESULTS: Biopsy needle passing through the renal sinus was identified in the patients with major (6 of 10; 60%) and minor complications (8 of 20; 40.0%) but not in the control groups. For patients with major complications, the needle-sinus distance was significantly shorter (5.11 mm ± 7.32 vs 11.14 mm ± 3.54; P = .023) and the needle-capsule distance was significantly longer (17.52 mm ± 8.04 vs 9.28 mm ± 3.29; P = .0004) than in control subjects. The bimodal distribution of cortical tangential angles (< 30° or ≥ 60°) in minor complication cases (17 of 20; 85.0%) was significantly greater than in the control group (8 of 20; 40.0%; odds ratio = 8.50; P = .004). CONCLUSIONS: This study identifies imaging risk factors in US-guided native kidney biopsy and recommends an algorithm to manage them, including appropriate needle path position between the renal capsule and sinus and proper needle cortical tangential angle.
2018
Ozturk A, Grajo JR, Gee MS, Benjamin A, Zubajlo RE, Thomenius KE, Anthony BW, Samir AE, Dhyani M. Quantitative Hepatic Fat Quantification in Non-alcoholic Fatty Liver Disease Using Ultrasound-Based Techniques: A Review of Literature and Their Diagnostic Performance. Ultrasound Med Biol. 2018;44 (12) :2461-2475.Abstract
Non-alcoholic fatty liver disease is a condition that is characterized by the presence of >5% fat in the liver and affects more than one billion people worldwide. If adequate and early precautions are not taken, non-alcoholic fatty liver disease can progress to cirrhosis and death. The current reference standard for detecting hepatic steatosis is a liver biopsy. However, because of the potential morbidity associated with liver biopsies, non-invasive imaging biomarkers have been extensively investigated. Magnetic resonance imaging-based methods have proven accuracy in quantifying liver steatosis; however, these techniques are costly and have limited availability. Ultrasound-based quantitative imaging techniques are increasingly utilized because of their widespread availability, ease of use and relative cost-effectiveness. Several ultrasound-based liver fat quantification techniques have been investigated, including techniques that measure changes in the acoustic properties of the liver caused by the presence of fat. In this review, we focus on quantitative ultrasound approaches and their diagnostic performance in the realm of non-alcoholic fatty liver disease.
Li Q, Yang L, Duan Y, Xiang F, McCarthy CJ, Thabet A, Cai W, Grajo JR, Baikpour M, McConnell R, et al. A Low-Cost Highly Configurable Phantom for Simulation of Imaging-Guided Endocavitary Procedures. Ultrasound Q. 2018.Abstract
We developed a method to create customizable phantoms suitable for endocavitary imaging and interventional research, based on the fabrication of an acrylic phantom mold, and development of a phantom matrix composed of gelatin, agar, graphite particles, and propanol. Our phantom was mechanically stable, easily fabricated, and highly adjustable, and its ultrasound (US) and magnetic resonance imaging (MRI) scans showed the qualification for the procedure guidance compared with the human prostate image using the same US system. To test the feasibility of the phantom for the research, the seeds placement guided by MRI/US fusion was performed, and the overall test error (distance from the seed center to the virtual lesion center in olives) was 2.59 ± 0.59 mm. We have created a simple, low-cost, configurable, gelatin-based phantom and tested its feasibility for simulating endorectal interventional US procedures. The design of the phantom mold and matrix is likely to be useful to the broader medical training community, and the preliminary data from the experiment of MRI/US-guided seeds placement showed its potential to test the clinical hypothesis in US research.
Chen M, Li Q, Karimian N, Yeh H, Duan Y, Fontan F, Aburawi MM, Anthony BW, Uygun K, Samir AE. Contrast-Enhanced Ultrasound to Quantify Perfusion in a Machine-Perfused Pig Liver, in 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC). ; 2018 :3128-3131.
Dhyani M, Xiang F, Li Q, Chen L, Li C, Bhan AK, Anthony B, Grajo JR, Samir AE. Ultrasound Shear Wave Elastography: Variations of Liver Fibrosis Assessment as a Function of Depth, Force and Distance from Central Axis of the Transducer with a Comparison of Different Systems. Ultrasound Med Biol. 2018;44 (11) :2209-2222.Abstract
We evaluated variation in fibrosis staging caused by depth, pre-load force and measurement off-axis distance on different ultrasound shear wave elastography (SWE) systems prospectively in 20 patients with diffuse liver disease. Shear wave speed (SWS) was measured with transient elastography, acoustic radiation force impulse (ARFI) and 2-D shear wave elastography (SWE). ARFI and 2-D-SWE measurements were obtained at different depths (3, 5 and 7 cm), with different pre-load forces (4, 7 and 10N and variable) and at 0, 2 and 4cm off the central axis of the transducer. A single, blinded pathologist staged fibrosis using the METAVIR system (F0-F4). Area under the receiver operating characteristic curve was charted to differentiate significant fibrosis (F ≥ 2). Depth was the only factor found to influence ARFI-derived values; no acquisition factors were found to affect 2-D-SWE SWS values. ARFI and 2-D-SWE for diagnosis of significant fibrosis at a depth of 7cm along the central axis had good diagnostic performance (areas under the receiver operating characteristic curve: 0.92 and 0.82, respectively), comparable to that of transient elastography. Further investigation of this finding will likely be of interest.
Brattain LJ, Telfer BA, Dhyani M, Grajo JR, Samir AE. Machine learning for medical ultrasound: status, methods, and future opportunities. Abdom Radiol (NY). 2018;43 (4) :786-799.Abstract
Ultrasound (US) imaging is the most commonly performed cross-sectional diagnostic imaging modality in the practice of medicine. It is low-cost, non-ionizing, portable, and capable of real-time image acquisition and display. US is a rapidly evolving technology with significant challenges and opportunities. Challenges include high inter- and intra-operator variability and limited image quality control. Tremendous opportunities have arisen in the last decade as a result of exponential growth in available computational power coupled with progressive miniaturization of US devices. As US devices become smaller, enhanced computational capability can contribute significantly to decreasing variability through advanced image processing. In this paper, we review leading machine learning (ML) approaches and research directions in US, with an emphasis on recent ML advances. We also present our outlook on future opportunities for ML techniques to further improve clinical workflow and US-based disease diagnosis and characterization.
Li Q, Xiang F, Lin X, Grajo JR, Yang L, Xu Y, Duan Y, Vyas U, Harisinghani M, Mahmood U, et al. The Role of Imaging in Prostate Cancer Care Pathway: Novel Approaches to Urologic Management Challenges Along Ten Imaging Touch Points. Urology. 2018.Abstract
We map out a typical prostate cancer care pathway through discussion of updates on modern imaging. Multiparametric MRI (mpMRI) is the most sensitive and specific imaging tool for diagnosis and local staging, transrectal ultrasound remains the most widely used technique for prostate biopsy guidance, CT and bone scan are useful in initial staging and recurrence detection. Novel imaging techniques in ultrasound elastography and mpMRI allow for increased lesion detection sensitivity and have the potential to enhance biopsy, while the development of new PET radiotracers has great promise for improved detection of local and metastatic disease in patients with biochemical recurrence.
Ozturk A, Grajo JR, Dhyani M, Anthony BW, Samir AE. Principles of ultrasound elastography. Abdominal Radiology. 2018.Abstract
Tissue stiffness has long been known to be a biomarker of tissue pathology. Ultrasound elastography measures tissue mechanical properties by monitoring the response of tissue to acoustic energy. Different elastographic techniques have been applied to many different tissues and diseases. Depending on the pathology, patient-based factors, and ultrasound operator-based factors, these techniques vary in accuracy and reliability. In this review, we discuss the physical principles of ultrasound elastography, discuss differences between different ultrasound elastographic techniques, and review the advantages and disadvantages of these techniques in clinical practice.
2017
Anvari A, Halpern EF, Samir AE. Essentials of Statistical Methods for Assessing Reliability and Agreement in Quantitative Imaging. Academic Radiology. 2017;PMID: 29241596.
Li Q, Lin X, Shao Y, Xiang F, Samir AE. Imaging and Screening of Thyroid Cancer. Radiol Clin North Am. 2017;55 (6) :1261-1271.Abstract
Ultrasound is the first-line diagnostic tool for diagnosis of thyroid diseases. The low aggressiveness of many thyroid cancers coupled with high sensitivity of sonography can lead to cancer diagnosis and treatment with no effect on outcomes. Ultrasound is recognized as the most important driver of thyroid cancer overdiagnosis. Ultrasound should not be used as a general screening tool and should be reserved for patients at high risk of thyroid cancer and in the diagnostic management of incidentally discovered thyroid nodules. With prescreening risk stratification and application of consensus criteria for nodule biopsy, the value of the diagnostic ultrasound can be maximized.
Dhyani M, Grajo JR, Bhan AK, Corey K, Chung R, Samir AE. Validation of Shear Wave Elastography Cutoff Values on the Supersonic Aixplorer for Practical Clinical Use in Liver Fibrosis Staging. Ultrasound Med Biol. 2017.Abstract

The purpose of this study was to determine the validity of previously established ultrasound shear wave elastography (SWE) cut-off values (≥F2 fibrosis) on an independent cohort of patients with chronic liver disease. In this cross-sectional study, approved by the institutional review board and compliant with the Health Insurance Portability and Accountability Act, 338 patients undergoing liver biopsy underwent SWE using an Aixplorer ultrasound machine (SuperSonic Imagine, Aix-en-Provence, France). Median SWE values were calculated from sets of 10 elastograms. A single blinded pathologist evaluated METAVIR fibrosis staging as the gold standard. The study analyzed 277 patients with a mean age of 48 y. On pathologic examination, 212 patients (76.5%) had F0-F1 fibrosis, whereas 65 (23.5%) had ≥F2 fibrosis. Spearman's correlation of fibrosis with SWE was 0.456 (p < 0.001). A cut-off value of 7.29 kPa yielded sensitivity of 95.4% and specificity of 50.5% for the diagnosis of METAVIR stage ≥F2 liver fibrosis in patients with liver disease using the SuperSonic Imagine Aixplorer SWE system.

Dhyani M, Grajo JR, Rodriguez D, Chen Z, Feldman A, Tambouret R, Gervais DA, Arellano RS, Hahn PF, Samir AE. Aorta-Lesion-Attenuation-Difference (ALAD) on contrast-enhanced CT: a potential imaging biomarker for differentiating malignant from benign oncocytic neoplasms. Abdominal Radiology. 2017 :1–10.Abstract

 

Objective: To evaluate whether the Aorta-Lesion-Attenuation-Difference on contrast-enhanced CT can aid in the differentiation of malignant and benign oncocytic renal neoplasms.

Materials and methods: Two independent cohorts—an initial (biopsy) dataset and a validation (surgical) dataset—with oncocytomas and chromophobe renal cell carcinomas (chRCC) were included in this IRB-approved retrospective study. A region of interest was placed on the renal mass and abdominal aorta on the same CT image slice to calculate an Aorta-Lesion- Attenuation-Difference (ALAD). ROC curves were plotted for different enhancement phases, and diagnostic performance of ALAD for differentiating chRCC from oncocytomas was calculated.

Results: Seventy-nine renal masses (56 oncocytomas, 23 chRCC) were analyzed in the initial (biopsy) dataset. Thirty-six renal masses (16 oncocytomas, 20 chRCC) were reviewed in the validation (surgical) cohort. ALAD showed a statistically significant difference between oncocytomas and chromophobes during the nephro- graphic phase (p < 0.001), early excretory phase (p < 0.001), and excretory phase (p = 0.029). The area under the ROC curve for the nephrographic phase was 1.00 (95% CI: 1.00–1.00) for the biopsy dataset and showed the narrowest confidence interval. At a threshold value of 25.5 HU, sensitivity was 100 (82.2%–100%) and specificity was 81.5 (61.9%–93.7%). When tested on the validation dataset on measurements made by an inde- pendent reader, the AUROC was 0.93 (95% CI: 0.84–1.00) with a sensitivity of 100 (80.0%–100%) and a specificity of 87.5 (60.4%–97.8%).

Conclusions: Nephrographic phase ALAD has potential to differentiate benign and malignant oncocytic renal neoplasms on contrast-enhanced CT if histologic evaluation on biopsy is indeterminate. 

 

2016
Sanchez Y, Anvari A, Samir AE, Arellano RS, Prabhakar AM, Uppot RN. Navigational Guidance and Ablation Planning Tools for Interventional Radiology. Curr Probl Diagn Radiol. 2016;S0363-0188(16)30110-4.Abstract

Image-guided biopsy and ablation relies on successful identification and targeting of lesions. Currently, image-guided procedures are routinely performed under ultrasound, fluoroscopy, magnetic resonance imaging, or computed tomography (CT) guidance. However, these modalities have their limitations including inadequate visibility of the lesion, lesion or organ or patient motion, compatibility of instruments in an magnetic resonance imaging field, and, for CT and fluoroscopy cases, radiation exposure. Recent advances in technology have resulted in the development of a new generation of navigational guidance tools that can aid in targeting lesions for biopsy or ablations. These navigational guidance tools have evolved from simple hand-held trajectory guidance tools, to electronic needle visualization, to image fusion, to the development of a body global positioning system, to growth in cone-beam CT, and to ablation volume planning. These navigational systems are promising technologies that not only have the potential to improve lesion targeting (thereby increasing diagnostic yield of a biopsy or increasing success of tumor ablation) but also have the potential to decrease radiation exposure to the patient and staff, decrease procedure time, decrease the sedation requirements, and improve patient safety. The purpose of this article is to describe the challenges in current standard image-guided techniques, provide a definition and overview for these next-generation navigational devices, and describe the current limitations of these, still evolving, next-generation navigational guidance tools.

Samir AE. The role and value of ultrasound elastography in the evaluation of thyroid nodules. Cancer. 2016;124 (11) :765-766.
Li Q, Vij A, Hahn PF, Xiang F, Samir AE. The Value of Active Ultrasound Surveillance for Patients With Small Testicular Lesions. Ultrasound Q. 2016.Abstract
This study aimed to determine whether active ultrasound surveillance may obviate the need for surgical resection in selected patients with small testicular lesions (STLs). A retrospective 11-year review was conducted of adults who were diagnosed with an STL on scrotal ultrasonography and who either had orchiectomy or sonographic follow-up during a period of at least 3 months. A total of 101 subjects were enrolled. Ultrasound findings, clinical features, histopathology/follow-up imaging were recorded. Logistic regression analysis was performed to select independent risk factors for the diagnosis of malignancy. Seventeen (16.8%) subjects underwent immediate surgery, 8 (7.9%) of 101 underwent surgery after ultrasound follow-up, and 76 (75.3%) of 101 were followed with ultrasound only. The follow-up period ranged from 1 to 7 months in the 8 patients who ultimately underwent surgery after ultrasound follow-up and from 6 to 84 months in the 76 patients followed up with ultrasound only. All 15 malignant cases underwent immediate surgery without follow-up sonography. The frequency of lesions, either benign at surgery or stable on ultrasound, was 85.1% (86 of 101; 95% confidence interval, 77%-91%). Logistic regression analysis showed that lesion size was the only independent risk factor for malignancy in hypoechoic STLs (P < 0.05). Most of the STLs were stable on serial sonograms and likely benign. Active ultrasound surveillance may be an appropriate management strategy in patients with STLs.
Anvari A, Dhyani M, Stephen AE, Samir AE. Reliability of Shear-Wave Elastography Estimates of the Young Modulus of Tissue in Follicular Thyroid Neoplasms. American Journal of Roentgenology. 2016;206 (3) :609-616.Abstract

 

OBJECTIVE: 

The purpose of this study is to determine the reliability of shear-wave elastographic estimates of the Young modulus in thyroid follicular neoplasms.

SUBJECTS AND METHODS: 

In this study, 35 adults with follicular nodules diagnosed by fine-needle aspiration (FNA) biopsy were enrolled. A single sonographer examined all nodules in three planes (sagittal, transverse, and transverse center). Two raters independently placed ROIs in each nodule. Intra- and interrater reliability were computed as intraclass correlation coefficients (ICCs) and were reported using the Guidelines for Reporting Reliability and Agreement Studies.

RESULTS: 

Thirty-five subjects with 35 follicular pattern nodules diagnosed by FNA biopsy were enrolled; 23 (65.7%) patients were female, with a mean age of 55.1 years (range, 23-85 years). For rater 1, intrarater agreement showed ICCs for single measurements of 0.87, 0.87, and 0.90 in the sagittal, transverse, and transverse center plans, respectively; ICCs for the median of multiple measurements were 0.97, 0.94, and 0.96 in the sagittal, transverse, and transverse center planes, respectively. For rater 2, intrarater agreement showed ICCs for single measurements of 0.94, 0.86, and 0.92 in the sagittal, transverse, and transverse center planes, respectively; ICCs for the median of multiple measurements were 0.97, 0.92, and 0.96 in the sagittal, transverse, and transverse center planes, respectively. Interrater agreement between measurements performed for the same subject showed ICCs for single measurements of 0.87, 0.87, and 0.80 in the sagittal, transverse, and transverse center planes, respectively; ICCs for the median of multiple measurements were 0.96, 0.93, and 0.92 in the sagittal, transverse, and transverse center planes, respectively.

CONCLUSION: 

ROI placement is a reliable method for estimating the Young modulus of tissue in follicular thyroid nodules.

 

2015
Anvari A, Dhyani M, Stephen A, Samir A. Reliability of Shear-Wave Elastography Estimates of the Young Modulus of Tissue in FollicularThyroid Neoplasms. American Journal of Roentgenology. 2015;277 (2) :565-573.Abstract

The purpose of this study is to determine the reliability of shear-wave elastographic estimates of the Young modulus in thyroid follicular neoplasms. In this study, 35 adults with follicular nodules diagnosed by fine-needle aspiration (FNA) biopsy were enrolled. A single sonographer examined all nodules in three planes (sagittal, transverse, and transverse center). Two raters independently placed ROIs in each nodule. Intra- and interrater reliability were computed as intraclass correlation coefficients (ICCs) and were reported using the Guidelines for Reporting Reliability and Agreement Studies. Thirty-five subjects with 35 follicular pattern nodules diagnosed by FNA biopsy were enrolled; 23 (65.7%) patients were female, with a mean age of 55.1 years (range, 23-85 years). For rater 1, intrarater agreement showed ICCs for single measurements of 0.87, 0.87, and 0.90 in the sagittal, transverse, and transverse center plans, respectively; ICCs for the median of multiple measurements were 0.97, 0.94, and 0.96 in the sagittal, transverse, and transverse center planes, respectively. For rater 2, intrarater agreement showed ICCs for single measurements of 0.94, 0.86, and 0.92 in the sagittal, transverse, and transverse center planes, respectively; ICCs for the median of multiple measurements were 0.97, 0.92, and 0.96 in the sagittal, transverse, and transverse center planes, respectively. Interrater agreement between measurements performed for the same subject showed ICCs for single measurements of 0.87, 0.87, and 0.80 in the sagittal, transverse, and transverse center planes, respectively; ICCs for the median of multiple measurements were 0.96, 0.93, and 0.92 in the sagittal, transverse, and transverse center planes, respectively. ROI placement is a reliable method for estimating the Young modulus of tissue in follicular thyroid nodules.

Dhyani M, Gee MS, Misdraji J, Israel EJ, Shah U, Samir AE. Feasibility study for assessing liver fibrosis in paediatric and adolescent patients using real-time shear wave elastography. J Med Imaging Radiat Oncol. 2015.

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