Publications by authors named "Hyun-Jung Jang"

93 Publications

The added value of contrast-enhanced ultrasound in evaluation of indeterminate small solid renal masses and risk stratification of cystic renal lesions.

Eur Radiol 2021 Apr 29. Epub 2021 Apr 29.

Toronto Joint Department of Medical Imaging, University Health Network, Sinai Health System and Women's College Hospital, University of Toronto, Toronto, ON, Canada.

Objectives: To investigate accuracy of contrast-enhanced ultrasound (CEUS) to characterize indeterminate small solid renal masses (sSRMs), excluding lipid-rich AMLs, and cystic renal masses (CRMs) according to the proposed Bosniak Classification 2019 MATERIALS AND METHODS: CEUS of pathology-proven CRMs and sSRMs (without definite enhancement or macroscopic fat on CT/MRI), and CRMs with ≥18 months follow-up were retrospectively reviewed. Two radiologists blindly categorized CRMs according to new Bosniak Classification on CT/MRI. On CEUS, two other radiologists evaluated arterial-phase enhancement of sSRMs relative to renal cortex and categorized CRMs following new Bosniak Classification. Fisher's exact/chi-squared test was used to compare categorical variables, and Cohen κ statistics for inter-observer agreement RESULTS: A total of 237 patients had 241 lesions: 161 pathology-proven sSRMs (122 malignant and 39 benign), 29 pathology-proven CRMs, 51 CRMs with adequate follow-up. Arterial-phase enhancement < renal cortex predicted malignancy with specificity of 97.4% (38/39) (CI 85.6-99.9%), and positive predictive value (PPV) of 98.2% (54/55) (CI 90.4-99.9%). Inter-observer kappa was 0.95. In pathology-proven CRMS, sensitivity of CEUS vs CT/MRI was 100% (15/15) (CI 79.6-100%) vs 60% (9/15) (CI 35.8-80.1%) (p value = .002) and negative predictive value (NPV) 100% (2/2) (CI 17.8-100%) vs 25% (2/8 ) (CI 4.4-59.1%) (p value < 0.0001), with similar specificity (50%) and PPV- 88.2% (15/17) (CI 65.7-97.9%) vs 81.8% (9/11) (CI 52.3-96.8%) ( p value = 0.586). Bosniak Classification inter-observer kappa was 0.92 for CEUS vs 0.68 for CT/MRI (p value = 0.009).

Conclusion: In our cohort, CEUS had high specificity and PPV to diagnose RCC in sSRMs excluding lipid-rich AML. CEUS had significantly higher sensitivity/NPV to diagnose malignancy in CRMs as compared to CT/MRI.

Key Points: • Once lipid-rich AML is excluded by the other modalities, sSRM arterial phase hypo-enhancement relative to renal cortex on CEUS yielded high specificity (97.4%) and PPV (98.2%) to diagnose RCC. • When applying the proposed Bosniak Classification 2019, CEUS showed higher sensitivity compared to CT/MRI (100% vs 60%), p value=.0024, in the stratification of cystic renal masses to diagnose malignancy. • CEUS may reduce the number of CT/MRI Bosniak IIF lesions by assigning them to either II or III/IV categories.
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http://dx.doi.org/10.1007/s00330-021-07964-0DOI Listing
April 2021

Use of CEUS LI-RADS for the Accurate Diagnosis of Nodules in Patients at Risk for Hepatocellular Carcinoma: A Validation Study.

Radiol Imaging Cancer 2020 03 27;2(2):e190014. Epub 2020 Mar 27.

Departments of Radiology (A. Makoyeva, A. Medellin, S.R.W.) and Medicine (S.R.W.), University of Calgary, Foothills Medical Centre, 1403 29th St NW, Calgary, AB, Canada T2N 2T9; and Department of Medical Imaging, University of Toronto, Toronto, Canada (T.K.K., H.J.J.).

Purpose: To validate the contrast agent-enhanced US Liver Imaging Reporting and Data System (CEUS LI-RADS) algorithm for accurate diagnosis of hepatocellular carcinoma (HCC) and categorization of all nodules encountered in patients at risk for HCC.

Materials And Methods: A single-center retrospective review of 196 nodules in 184 patients at risk for HCC (consisting of 139 HCCs, 18 non-HCC malignancies, and 39 benign nodules) was performed in a three-reader blinded read format, with the use of the CEUS LI-RADS algorithm. Pathologic confirmation was available for 143 nodules (122 HCCs, 18 non-HCC malignancies, and three benign nodules). Nodule sizes ranged between 1.0 and 16.2 cm. Nodules assessed with contrast-enhanced US were assigned various CEUS LI-RADS categories by three blinded readers. CEUS LI-RADS categorization was then compared against histopathologic findings, concurrent CT, and/or MR images or follow-up imaging to assess diagnostic accuracy of CEUS LI-RADS. In addition, the proportion of HCC in all LI-RADS (LR) categories, univariable and multivariable feature analysis, and interrater agreement using Light κ were determined.

Results: The LR-5 category, determined through radiologist categorization of nodules using the CEUS LI-RADS criteria, showed sensitivity, specificity, positive predictive value, and negative predictive value of 86% (119 of 139), 96% (55 of 57), 98% (119 of 121), and 73% (55 of 75), respectively, for the diagnosis of HCC. Two false-positive cases of LR-5 included a cholangiocarcinoma and a combined hepatocellular and cholangiocarcinoma. The remainder of the cholangiocarcinomas in the sample ( = 8) were appropriately categorized as LR-M. Multivariable logistic regression analysis showed that washout of greater than 60 seconds was the contrast-enhanced US feature most predictive of HCC diagnosis, whereas washout of less than 60 seconds was the feature most predictive of nonhepatocellular malignancy. The proportion of HCC nodules categorized in the LR-M and LR-4 categories was 35% and 20%, respectively. Light κ agreement between readers for LI-RADS categorization was 90%.

Conclusion: This study showed excellent specificity for the CEUS LI-RADS LR-5 category, allowing for confident imaging diagnosis of HCC, without necessity for pathologic confirmation. In addition, there was accurate differentiation of HCC from non-HCC malignancies and benign nodules. Only a single cholangiocarcinoma was misdiagnosed as category LR-5, with the remainder of the cholangiocarcinomas in the sample appropriately characterized as category LR-M. Abdomen/GI, Evidence Based Medicine, Liver, Neoplasms-Primary, Ultrasound-Contrast© RSNA, 2020.
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http://dx.doi.org/10.1148/rycan.2020190014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7983739PMC
March 2020

Recognizing the Role of the Reticuloendothelial System in the Late Phase of US Contrast Agents.

Radiology 2021 Feb 8;298(2):287-291. Epub 2020 Dec 8.

From the Department of Medical Imaging, University of Toronto, 610 University Ave, Room 3-964, Toronto, ON, Canada M5G 2M9; and Joint Department of Medical Imaging, University Health Network, Sinai Health System, Women's College Hospital, Toronto, Canada.

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http://dx.doi.org/10.1148/radiol.2020203245DOI Listing
February 2021

Radiological tumor response and histopathological correlation of hepatocellular carcinoma treated with stereotactic body radiation therapy as a bridge to liver transplantation.

Abdom Radiol (NY) 2021 Apr 19;46(4):1572-1585. Epub 2020 Oct 19.

Joint Department of Medical Imaging, University Health Network/Mount Sinai Hospital/Women's College Hospital, 585 University Avenue, Toronto, ON, M5G 2N2, Canada.

Purpose: To assess the imaging findings of hepatocellular carcinoma (HCC) treated with stereotactic body radiation therapy (SBRT) as a bridging therapy prior to liver transplantation (LT), with histopathological correlation at liver explant.

Methods: Our institutional review board approved this retrospective study. The study subjects included 25 HCC lesions in 23 patients (20 males; median age, 60 years; range 41-68 years) who underwent LT after SBRT for HCC as a bridge to LT in a single tertiary referral institution over a 12-year period. Target HCC lesions were assessed for imaging biomarkers on contrast-enhanced CT or MRI including change in HCC diameter and assessment of percentage necrosis. The radiologic response at pre-LT imaging was compared to explant pathology.

Results: There was a positive correlation between the tumor size (Spearman's ρ = 0.86; p < 0.001) and percentage necrosis (p < 0.001) on Pre-LT imaging and those on pathology. Partial response (PR), stable disease (SD), and progressive disease (PD) according to RECIST 1.1 were seen in 8 (32%), 15 (60%), and 2 (8%) lesions on pre-LT imaging, respectively. Of the 15 lesions with radiologic SD, 5/15 (33%) showed necrosis of more than 50% on post-SBRT imaging, while 9/15 (60%) showed necrosis of more than 50% at explant pathologic analysis, showing a tendency to underestimate the degree of tumor necrosis compared to pathology.

Conclusion: RECIST 1.1 radiologic response criteria may underestimate the response to treatment with SBRT, and radiologic estimation of percent tumor necrosis was more closely correlated with pathologic percent tumor necrosis.
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http://dx.doi.org/10.1007/s00261-020-02821-yDOI Listing
April 2021

Convolutional neural networks versus radiologists in characterization of small hypoattenuating hepatic nodules on CT: a critical diagnostic challenge in staging of colorectal carcinoma.

Sci Rep 2020 09 17;10(1):15248. Epub 2020 Sep 17.

Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada.

Our objective was to compare the diagnostic performance and diagnostic confidence of convolutional neural networks (CNN) to radiologists in characterizing small hypoattenuating hepatic nodules (SHHN) in colorectal carcinoma (CRC) on CT scans. Retrospective review of CRC CT scans over 6-years yielded 199 patients (550 SHHN) defined as < 1 cm in diameter. The reference standard was established through 1-year stability/MRI for benign or nodule evolution for malignant nodules. Five CNNs underwent supervised training on 150 patients (412 SHHN). The remaining 49 patients (138 SHHN) were used as testing-set to compare performance of 3 radiologists to CNN, measured through ROC AUC analysis of confidence rating assigned to each nodule by the radiologists. Multivariable modeling was used to compensate for radiologist bias from visible findings other than SHHN. In characterizing SHHN as benign or malignant, the radiologists' mean AUC ROC (0.96) was significantly higher than CNN (0.84, p = 0.0004) but equivalent to CNN adjusted through multivariable modeling for presence of synchronous ≥ 1 cm liver metastases (0.95, p = 0.9). The diagnostic confidence of radiologists and CNN were analyzed. There were significantly lower number of nodules rated with low confidence by CNN (19.6%) and CNN with liver metastatic status (18.1%) than two (38.4%, 44.2%, p < 0.0001) but not a third radiologist (11.1%, p = 0.09). We conclude that in CRC, CNN in combination with liver metastatic status equaled expert radiologists in characterizing SHHN but with better diagnostic confidence.
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http://dx.doi.org/10.1038/s41598-020-71364-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7499427PMC
September 2020

Collateral Damage: The Impact of the COVID-19 Pandemic on Acute Abdominal Emergency Presentations.

J Am Coll Radiol 2020 11 20;17(11):1443-1449. Epub 2020 Aug 20.

Department of Medical Imaging, University Health Network, University of Toronto, Toronto, Ontario, Canada.

Introduction: In March 2020, the World Health Organization declared a pandemic caused by a novel coronavirus. Public information created awareness as well as concern in the general population. There has been a reported decrease in the number of patients attending emergency departments (ED) during the pandemic. This is the first study to determine differences in the types of presenting illnesses, severity, and rate of resultant surgical intervention during the pandemic.

Methods And Materials: We carried out a retrospective, observational cohort study comparing two groups of patients attending the ED at our tertiary-care academic hospital. A historical comparison cohort was obtained by reviewing the number of patients referred by the ED for abdominal CT between March 15 and April 15, 2020, compared with March 15 and April 15, 2019. CT reports were reviewed; primary pathologies, complications, and subsequent surgical intervention were documented and compared between the two groups.

Results: In all, 733 patients were included in the 2019 cohort, and 422 patients were included in the 2020 cohort. In 2019, 32.7% had positive CT findings, increasing to 50.5% in 2020. The number of complications increased from 7.9% to 19.7%. The rate requiring surgical intervention increased from 26.3% to 47.6% in 2020.

Conclusion: To date, there is little published data regarding the presentation and severity of illnesses during the coronavirus disease 2019 pandemic. This information has important public health implications, highlighting the need to educate patients to continue to present to hospital services during such crises, including if a purported second wave of COVID-19 arises.
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http://dx.doi.org/10.1016/j.jacr.2020.08.010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7439814PMC
November 2020

Emerging Evidence of the Utility of Perfluorobutane-enhanced US as a Diagnostic Test for Hepatocellular Carcinoma.

Radiology 2020 10 4;297(1):117-119. Epub 2020 Aug 4.

From the Joint Department of Medical Imaging, University Health Network/Mount Sinai Hospital/Women's College Hospital, University of Toronto, 585 University Ave, Toronto, ON, Canada M5G 2N2.

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http://dx.doi.org/10.1148/radiol.2020202763DOI Listing
October 2020

Imaging diagnosis and staging of pancreatic ductal adenocarcinoma: a comprehensive review.

Insights Imaging 2020 Apr 25;11(1):58. Epub 2020 Apr 25.

Joint Department of Medical Imaging, University Health Network, Mount Sinai Hospital and Women's College Hospital, University of Toronto, Toronto, ON, Canada.

Pancreatic ductal adenocarcinoma (PDAC) has continued to have a poor prognosis for the last few decades in spite of recent advances in different imaging modalities mainly due to difficulty in early diagnosis and aggressive biological behavior. Early PDAC can be missed on CT due to similar attenuation relative to the normal pancreas, small size, or hidden location in the uncinate process. Tumor resectability and its contingency on the vascular invasion most commonly assessed with multi-phasic thin-slice CT is a continuously changing concept, particularly in the era of frequent neoadjuvant therapy. Coexistent celiac artery stenosis may affect the surgical plan in patients undergoing pancreaticoduodenectomy. In this review, we discuss the challenges related to the imaging of PDAC. These include radiological and clinical subtleties of the tumor, evolving imaging criteria for tumor resectability, preoperative diagnosis of accompanying celiac artery stenosis, and post-neoadjuvant therapy imaging. For each category, the key imaging features and potential pitfalls on cross-sectional imaging will be discussed. Also, we will describe the imaging discriminators of potential mimickers of PDAC.
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http://dx.doi.org/10.1186/s13244-020-00861-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7183518PMC
April 2020

Characterization of Indeterminate Liver Lesions on CT and MRI With Contrast-Enhanced Ultrasound: What Is the Evidence?

AJR Am J Roentgenol 2020 06 17;214(6):1295-1304. Epub 2020 Mar 17.

Joint Department of Medical Imaging, University Health Network, Mount Sinai Hospital and Women's College Hospital, University of Toronto, 585 University Ave, Toronto, ON M5G 2N2, Canada.

CT or MRI is most commonly used for characterizing focal hepatic lesions. However, findings on CT and MRI are occasionally indeterminate. Contrast-enhanced ultrasound (CEUS), with its unique characteristics as a purely intravascular contrast agent and real-time evaluation of enhancement, is a useful next step. The purpose of this article is to review the evidence for performing CEUS in the assessment of indeterminate hepatic lesions seen on CT and MRI. CEUS is a useful problem-solving tool in the evaluation of liver lesions that are indeterminate on CT and MRI. Uses include detection of arterial phase hyperenhancement; differentiation between hepatocellular carcinoma and intrahepatic cholangiocarcinoma; determination of benign versus malignant tumor thrombus, benign versus neoplastic cystic hepatic lesions, and hepatocellular adenoma versus focal nodular hyperplasia; and monitoring for recurrence in postablative therapies. CEUS can help establish a confident diagnosis and determine the need for further invasive diagnosis or treatment.
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http://dx.doi.org/10.2214/AJR.19.21498DOI Listing
June 2020

Diagnostic imaging of hepatocellular carcinoma at community hospitals and their tertiary referral center in the era of LI-RADS: a quality assessment study.

Abdom Radiol (NY) 2019 12;44(12):4028-4036

Department of Medical Imaging, University of Toronto, Toronto, ON, Canada.

Purpose: To assess guideline compliance and quality of hepatocellular carcinoma, (HCC) diagnostic imaging within community hospitals (CH) and their Tertiary referral center (TRC) in a moderately high incidence region.

Methods: Initial diagnostic workup CT/MRI scans of 251 patients (122 CH, 112 TRC, 17 Non-TRC academic) with HCC over a 15-month period were assessed for Liver reporting and Data System (LI-RADS) guideline compliance. 269 scans (182 CT, 87 MRI) were qualitatively evaluated by 2 independent blinded radiologists for arterial timing, overall image quality, noise and sharpness, with quantification of interobserver variability. The contrast enhancement ratio (CER) for the largest HCC on each scan was calculated using pre- and post-contrast images.

Results: 103/104 (99%) of TRC and 44/78 (56%) of CH CTs adhered to LI-RADS imaging guidelines (P < 0.0001). Lack of delayed phase accounted for 32/34 (94%) of noncompliant CH CTs. Regarding MRI, 19/19 (100%) of TRC and 60/68 (88%) of CH scans were adherent (P = 0.12). For both modalities, overall image quality, noise and sharpness were rated significantly higher for TRC than CH. There was moderate interobserver agreement with intraclass correlation coefficient of 0.73, 0.70 and 0.63, respectively. Arterial-phase timing was rated adequate for CT in 75/104 TRC (72%) and 10/68 (14%) CH scans (P < 0.0001) and for MRI in 8/19 (42%) TRC and 23/68 (33%) CH scans (P = 0.17). The CER was significantly higher for TRC versus CH (2.9 vs. 1.9, P < 0.001) and MRI (0.9 vs. 0.7, P = 0.03).

Conclusions: Community hospital HCC diagnostic scans significantly lag in critical quality parameters of tumor enhancement, arterial phase timing, perceived image quality, and LI-RADS CT technique compliance compared to a TRC.
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http://dx.doi.org/10.1007/s00261-019-02237-3DOI Listing
December 2019

CT and MR imaging findings of the livers in adults with Fontan palliation: an observational study.

Abdom Radiol (NY) 2020 01;45(1):188-202

Joint Department of Medical Imaging, Toronto General Hospital, University of Toronto, 585 University Avenue, Toronto, ON, M5G 2N2, Canada.

Purpose: To describe liver imaging findings and complications on computed tomography (CT) or magnetic resonance imaging (MRI) in adults with Fontan palliation and investigate whether imaging features show correlations with clinical and physiological parameters.

Methods: Our Institutional Review Board approved this retrospective study. Two blinded abdominal radiologists reviewed abdominal CT (n = 21) and MRI (n = 16) images between September 2011 and October 2017 in 37 adults (median age 27 years, interquartile range 21-36 years, 14 males [38%]) with a Fontan palliation (median post-Fontan duration 22 years, interquartile range 19-28 years). Correlation between CT/MRI findings and clinical parameters including laboratory results within 6 months of CT/MRI examinations was assessed by Spearman's rank correlation coefficient.

Results: Lobulated hepatic surface and blunt hepatic edge were seen in 92% (34/37) and 95% (35/37) of patients, respectively. Surface nodularity was noted in 32% (12/37). In 7 patients, there were 11 hepatic nodules which showed arterial-phase hyperenhancement and washout. Among them, 2 were biopsy-proven hepatocellular carcinomas (HCCs), and the remaining 9 were focal nodular hyperplasia (FNH)-like nodules. Suprahepatic inferior vena cava (IVC) diameter showed positive correlations with post-Fontan duration (p < 0.01), serum gamma-glutamyl transferase (p < 0.01), and total bilirubin (p < 0.01).

Conclusion: The livers in post-Fontan adults show a unique morphology of blunt edge and lobulating surface with occasional nodularity. There is a diagnostic challenge in distinguishing HCCs from FNH-like nodules in post-Fontan population due to overlapping imaging findings. Suprahepatic IVC diameter is a potentially useful imaging marker that reflects hepatic dysfunction in Fontan palliation.
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http://dx.doi.org/10.1007/s00261-019-02119-8DOI Listing
January 2020

Contrast-enhanced ultrasound approach to the diagnosis of focal liver lesions: the importance of washout.

Ultrasonography 2019 Oct 17;38(4):289-301. Epub 2019 Mar 17.

Joint Department of Medical Imaging, University of Toronto, Toronto, Canada.

Contrast-enhanced ultrasound (CEUS) is a powerful technique for differentiating focal liver lesions (FLLs) without the risks of potential nephrotoxicity or ionizing radiation. In the diagnostic algorithm for FLLs on CEUS, washout is an important feature, as its presence is highly suggestive of malignancy and its characteristics are useful in distinguishing hepatocellular from nonhepatocellular malignancies. Interpreting washout on CEUS requires an understanding that microbubble contrast agents are strictly intravascular, unlike computed tomography or magnetic resonance imaging contrast agents. This review explains the definition and types of washout on CEUS in accordance with the 2017 version of the CEUS Liver Imaging Reporting and Data System and presents their applications to differential diagnosis with illustrative examples. Additionally, we propose potential mechanisms of rapid washout and describe the washout phenomenon in benign entities.
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http://dx.doi.org/10.14366/usg.19006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6769186PMC
October 2019

Imaging post-stereotactic body radiation therapy responses for hepatocellular carcinoma: typical imaging patterns and pitfalls.

Abdom Radiol (NY) 2019 05;44(5):1795-1807

Joint Department of Medical Imaging, University Health Network, Mount Sinai Hospital and Women's College Hospital, University of Toronto, 585 University Avenue, Toronto, ON, M5G 2N2, Canada.

Stereotactic body radiation therapy (SBRT) has increased utility in the management of hepatocellular carcinoma (HCC) ranging from local therapy in early-stage HCC not suitable for other focal therapies to end-stage HCC. As the indications for the use of SBRT in HCC expand, diagnostic imaging is being increasingly used to assess response to treatment. The imaging features of tumor response do not parallel those of other focal therapies such as radiofrequency ablation or trans-arterial chemoembolization that immediately devascularize the tumor. The tumor response to SBRT on imaging takes much longer and often shows gradual changes including the reduction of enhancement and size over several months. It is essential to recognize the typical imaging patterns of response, as well as the appearance of focal liver reaction in the non-target liver that can confound image interpretation. The timing of treatment response assessment imaging is fundamental to minimize the potential for false negative response. The purpose of this article is to review the variable post-SBRT imaging features of HCC and adjacent liver parenchyma and discuss the potential pitfalls of imaging evaluation after SBRT for HCC.
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http://dx.doi.org/10.1007/s00261-019-01901-yDOI Listing
May 2019

Reproducibility of 2 Liver 2-Dimensional Shear Wave Elastographic Techniques in the Fasting and Postprandial States.

J Ultrasound Med 2019 Jul 11;38(7):1739-1745. Epub 2018 Dec 11.

Departments of Medical Imaging, Toronto, Ontario, Canada.

Objectives: The purpose of this study was to compare the reliability and agreement of 2 methods of 2-dimensional (2D) shear wave elastography (SWE) on liver stiffness in healthy volunteers. We also assessed effects of the prandial state and operator experience on measurements.

Methods: Two operators, 1 experienced and 1 novice, independently examined 20 healthy volunteers with 2D SWE on 2 ultrasound machines (Aixplorer [SuperSonic Imagine, Aix-en-Provence, France] and Aplio 500 [Canon Medical Systems Corporation, Otawara, Japan]). Volunteers were scanned 8 times by the operators using both machines in fasting and postprandial states. Agreement was evaluated by a Bland-Altman analysis, and the correlation was assessed by the Pearson correlation and intraclass correlation coefficients (ICCs). An analysis of variance was conducted to determine the contribution of the machine, prandial state, and operator experience to the variability.

Results: Agreement assessed by Bland-Altman plots showed no statistically significant difference in measured liver stiffness between the machines (mean difference, -0.8%; 95% confidence interval, -3.7%, 2.1%), with a critical difference of 1.36 kPa. The correlation was good to excellent for both the crude overall Pearson coefficient and the ICC, both measuring 0.88 (95% confidence interval, 0.82, 0.92). Subclass ICCs for the fasting state, postprandial state, novice operator, and experienced operator were 0.89, 0.88, 0.90, and 0.86, respectively. The 2-way mixed effect analysis of variance showed that the volunteers accounted for 86.3% of variation in median liver stiffness, with no statistically significant contribution from operator experience, the prandial state, or the machine (P = .108, .067, and .296, respectively).

Conclusions: Our study showed that the 2D SWE techniques had a high degree of reliability and agreement in measurement of liver stiffness in a healthy population. Operator experience and the prandial state did not impart significant variability to stiffness measurements.
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http://dx.doi.org/10.1002/jum.14862DOI Listing
July 2019

Ultrasound Imaging of Hepatocellular Adenoma Using the New Histology Classification.

Ultrasound Med Biol 2019 01 3;45(1):1-10. Epub 2018 Nov 3.

Department of Ultrasound, Zhongshan Hospital, Fudan University, Shanghai, China.

Hepatocellular adenoma is a rare benign liver tumor. Predisposing factors include hepatic storage diseases and some genetic conditions. A new histology-based classification has been proposed but to date, the corresponding ultrasound imaging features have not been reported. Here we review the new classification scheme and discuss the corresponding features on contrast-enhanced ultrasound imaging.
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http://dx.doi.org/10.1016/j.ultrasmedbio.2018.06.015DOI Listing
January 2019

Successful Integration of Contrast-enhanced US into Routine Abdominal Imaging.

Radiographics 2018 Sep-Oct;38(5):1454-1477. Epub 2018 Jul 30.

From the Department of Medical Imaging, University of Toronto, University Health Network, Toronto General Hospital, 585 University Ave, Toronto, ON, Canada M5G 2N2.

Contrast material-enhanced US is recognized increasingly as a useful tool in a wide variety of hepatic and nonhepatic applications. The modality recently was approved for limited use for liver indications in adult and pediatric patients in the United States. Contrast-enhanced US uses microbubbles of gas injected intravenously as a contrast agent to demonstrate blood flow and tissue perfusion. The growing worldwide application of contrast-enhanced US in multiple organ systems is due largely to its advantages, including high contrast resolution (sensitivity to the contrast agent), real-time imaging, lack of nephrotoxicity, the purely intravascular property of microbubble contrast agents that allows the use of disruption-replenishment techniques, and repeatability during the same examination. Through illustrative cases, common useful clinical scenarios are discussed, including characterization of liver and renal masses, especially indeterminate lesions at CT or MRI; differentiation of neoplastic cysts from nonneoplastic cysts in various organs; differentiation of tumor thrombus from bland thrombus; and assessment after a renal transplant or local ablative therapy. Common applications in the biliary system, pancreas, spleen, and vasculature also are introduced. Successful routine use of contrast-enhanced US requires an efficient setup and workflow and a thorough understanding of appropriate clinical indications and its advantages that provide added value after CT and MRI. This article familiarizes radiologists with common abdominal applications of contrast-enhanced US and guides them to implement contrast-enhanced US successfully in their clinical practice. Online supplemental material is available for this article. RSNA, 2018.
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http://dx.doi.org/10.1148/rg.2018170152DOI Listing
December 2018

Reader agreement and accuracy of ultrasound features for hepatic steatosis.

Abdom Radiol (NY) 2019 01;44(1):54-64

Department of Radiology, University of California San Diego, 200 W. Arbor Drive #8756, San Diego, CA, 92103-8756, USA.

Purpose: The purpose of the study is to assess the reader agreement and accuracy of eight ultrasound imaging features for classifying hepatic steatosis in adults with known or suspected hepatic steatosis.

Methods: This was an IRB-approved, HIPAA-compliant prospective study of adult patients with known or suspected hepatic steatosis. All patients signed written informed consent. Ultrasound images (Siemens S3000, 6C1HD, and 4C1 transducers) were acquired by experienced sonographers following a standard protocol. Eight readers independently graded eight features and their overall impression of hepatic steatosis on ordinal scales using an electronic case report form. Duplicated images from the 6C1HD transducer were read twice to assess intra-reader agreement. Intra-reader, inter-transducer, and inter-reader agreement were assessed using intraclass correlation coefficients (ICC). Features with the highest intra-reader agreement were selected as predictors for dichotomized histological steatosis using Classification and Regression Tree (CART) analysis, and the accuracy of the decision rule was compared to the accuracy of the radiologists' overall impression.

Results: 45 patients (18 males, 27 females; mean age 56 ± 12 years) scanned from September 2015 to July 2016 were included. Mean intra-reader ICCs ranged from 0.430 to 0.777, inter-transducer ICCs ranged from 0.228 to 0.640, and inter-reader ICCs ranged from 0.014 to 0.561. The CART decision rule selected only large hepatic vein blurring and achieved similar accuracy to the overall impression (74% to 75% and 68% to 72%, respectively).

Conclusions: Large hepatic vein blurring, liver-kidney contrast, and overall impression provided the highest reader agreement. Large hepatic vein blurring may provide the highest classification accuracy for dichotomized grading of hepatic steatosis.
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http://dx.doi.org/10.1007/s00261-018-1683-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6310678PMC
January 2019

Case Report: Filaria or Megasperm? A Cause of an Ultrasonographic "Filarial Dance Sign".

Am J Trop Med Hyg 2018 07 10;99(1):102-103. Epub 2018 May 10.

Tropical Disease Unit, Toronto General Hospital, University of Toronto, Toronto, Canada.

Bancroftian filariasis can cause genital abnormalities related to chronic inflammation and obstruction of the afferent lymphatic vessels, and may demonstrate a "filarial dance sign" on scrotal ultrasound with mobile echogenic particles observed. We present a patient with a positive "filarial dance sign," travel within Latin America, and negative filarial serology.
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http://dx.doi.org/10.4269/ajtmh.18-0234DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6085792PMC
July 2018

Abdominal imaging findings in adult patients with Fontan circulation.

Insights Imaging 2018 Jun 5;9(3):357-367. Epub 2018 Apr 5.

Department of Medical Imaging, Toronto General Hospital, 585 University Avenue, Toronto, ON, M5G 2N2, Canada.

The Fontan procedures, designed to treat paediatric patients with functional single ventricles, have markedly improved the patient's survival into adulthood. The physiology of the Fontan circuit inevitably increases systemic venous pressure, which may lead to multi-system organ failure in the long-term follow-up. Fontan-associated liver disease (FALD) can progress to liver cirrhosis with signs of portal hypertension. Focal nodular hyperplasia-like nodules commonly develop in FALD. Imaging surveillance is often performed to monitor the progression of FALD and to detect hepatocellular carcinoma, which infrequently develops in FALD. Other abdominal abnormalities in post-Fontan patients include protein losing enteropathy and pheochromocytoma/paraganglioma. Given that these abdominal abnormalities are critical for patient management, it is important for radiologists to become familiar with the abdominal abnormalities that are common in post-Fontan patients on cross-sectional imaging.

Teaching Points: • Fontan procedure for functional single ventricle has improved patient survival into adulthood. • Radiologists should be familiar with unique imaging findings of Fontan-associated liver disease. • Focal nodular hyperplasia-like nodules commonly develop in Fontan-associated liver disease. • Hepatocellular carcinoma, protein-losing enteropathy, pheochromocytoma/paraganglioma may develop.
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http://dx.doi.org/10.1007/s13244-018-0609-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5991003PMC
June 2018

How to perform Contrast-Enhanced Ultrasound (CEUS).

Ultrasound Int Open 2018 Jan 7;4(1):E2-E15. Epub 2018 Feb 7.

P.Stradina Clinical University Hospital, Diagnosic Radiology Institute, Riga, Latvia.

"How to perform contrast-enhanced ultrasound (CEUS)" provides general advice on the use of ultrasound contrast agents (UCAs) for clinical decision-making and reviews technical parameters for optimal CEUS performance. CEUS techniques vary between centers, therefore, experts from EFSUMB, WFUMB and from the CEUS LI-RADS working group created a discussion forum to standardize the CEUS examination technique according to published evidence and best personal experience. The goal is to standardise the use and administration of UCAs to facilitate correct diagnoses and ultimately to improve the management and outcomes of patients.
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http://dx.doi.org/10.1055/s-0043-123931DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5802984PMC
January 2018

Contrast-enhanced ultrasound of the liver: technical and lexicon recommendations from the ACR CEUS LI-RADS working group.

Abdom Radiol (NY) 2018 04;43(4):861-879

Division of Gastroenterology, University of Calgary, Calgary, Canada.

Contrast-enhanced ultrasound (CEUS) is a specific form of ultrasound imaging performed with intravenous administration of microbubble contrast agents. It has been extensively used for liver tumor characterization and was recently added to the American College of Radiology Liver Imaging Reporting and Data System (CEUS LI-RADS). This paper describes technical recommendations for successful liver CEUS lesion characterization, and provides imaging protocol and Lexicon of imaging findings.
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http://dx.doi.org/10.1007/s00261-017-1392-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5886815PMC
April 2018

Cholangiocarcinoma and its mimickers in primary sclerosing cholangitis.

Abdom Radiol (NY) 2017 12;42(12):2898-2908

Department of Medical Imaging, Toronto General Hospital, University of Toronto, 585, University Ave, Toronto, ON, M5G 2N2, Canada.

Cholangiocarcinoma (CCA) is the most common malignancy in primary sclerosing cholangitis (PSC). Approximately half of CCA are diagnosed within two years of initial diagnosis and often have a poor prognosis because of advanced tumor stage at the time of diagnosis. Thus, rigorous initial imaging evaluation for detecting CCA is important. CCA in PSC usually manifests as intrahepatic mass-forming or perihilar periductal-infiltrating type. Imaging diagnosis is often challenging due to pre-existing biliary strictures and heterogeneous liver. Multimodality imaging approach and careful comparison with prior images are often helpful in detecting small CCA. Ultrasound is widely used as an initial test, but has a limited ability to detect small tumors in the heterogeneous liver with PSC. MRI combined with MRCP is excellent to demonstrate focal biliary abnormalities as well as subtle liver masses. Contrast-enhanced ultrasound is useful to demonstrate CCA by demonstrating rapid and marked washout. In addition, there are other disease entities that mimic CCA including hepatocellular carcinoma, confluent hepatic fibrosis, IgG4-related sclerosing cholangitis, inflammatory mass, and focal fat deposition. In this pictorial essay, imaging findings of CCA in PSC is described and discuss the challenges in imaging surveillance for CCA in the patients with PSC. Imaging findings of the mimickers of CCA in PSC and their differentiating features are also discussed.
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http://dx.doi.org/10.1007/s00261-017-1328-8DOI Listing
December 2017

Contrast-enhanced ultrasound (CEUS) liver imaging reporting and data system (LI-RADS) 2017 - a review of important differences compared to the CT/MRI system.

Clin Mol Hepatol 2017 12 15;23(4):280-289. Epub 2017 Sep 15.

Department of Radiology, University of California, San Diego, USA.

Medical imaging plays an important role in the diagnosis and management of hepatocellular carcinoma (HCC). The Liver Imaging Reporting and Data System (LI-RADS) was initially created to standardize the reporting and data collection of CT and MR imaging for patients at risk for HCC. As contrast-enhanced ultrasound (CEUS) has been widely used in clinical practice, it has recently been added to the LI-RADS. While CEUS LI-RADS shares fundamental concepts with CT/MRI LI-RADS, there are key differences between the modalities reflecting dissimilarities in the underlying methods of image acquisition and types of contrast material. This review introduces a recent update of CEUS LI-RADS and explains the key differences from CT/MRI LI-RADS.
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http://dx.doi.org/10.3350/cmh.2017.0037DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5760002PMC
December 2017

CEUS LI-RADS: algorithm, implementation, and key differences from CT/MRI.

Abdom Radiol (NY) 2018 01;43(1):127-142

Division of Gastroenterology & Hepatology, University of California, 200 West Arbor Dr, San Diego, CA, 92103, USA.

Contrast-enhanced ultrasound (CEUS) is a specialized form of ultrasound (US) performed with an intravenous injection of microbubble contrast agents. It has been successfully used for a variety of applications including characterization of liver tumors. In April 2014, the American College of Radiology (ACR) convened a working group of international experts to develop ACR CEUS Liver Imaging Reporting and Data System (CEUS LI-RADS). An initial version of CEUS LI-RADS was published in August 2016. Although the CEUS LI-RADS concept and principles for liver lesion characterization, using dynamic contrast enhancement features, are similar to those for CT or MRI, there are significant differences between CT/MRI and CEUS LI-RADS. Therefore, CEUS LI-RADS has different diagnostic features and a unique characterization algorithm. The size of a lesion, the type and degree of arterial phase enhancement, the presence of washout, and the timing and degree of washout are the major features used for categorization. This paper describes key differences between CT/MRI and CEUS, and provides a diagnostic algorithm of CEUS LI-RADS with detailed, step-by-step instructions and imaging examples of CEUS LI-RADS categories.
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http://dx.doi.org/10.1007/s00261-017-1250-0DOI Listing
January 2018

Focal fat deposition in the liver: diagnostic challenges on imaging.

Abdom Radiol (NY) 2017 06;42(6):1667-1678

Department of Medical Imaging, University Health Network, University of Toronto, Toronto, ON, Canada.

While focal fat deposition in the liver mostly occurs in typical locations related to non-portal venous supply, unusual patterns of focal fat deposition, including multi-nodular, mass-like, and perivascular patterns, mimic malignancies and cause diagnostic challenges. Patients with unusual focal fat deposition often have potential underlying etiologies such as diabetes, alcohol abuse, metabolic disease, or various medications/chemotherapy. Some cases can be explained by non-portal venous supply or ischemia. Chemical-shift MRI or contrast-enhanced ultrasound (CEUS) is useful for non-invasive diagnosis of focal fat deposition. We illustrate a series of US, CT, and MR imaging features of focal fatty deposition in the liver mimicking other conditions and seek possible causes. Understanding of imaging patterns of focal fat deposition and its potential causes can help a non-invasive diagnosis by performing confirmatory imaging tests and prevent unnecessary invasive procedures.
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http://dx.doi.org/10.1007/s00261-017-1049-zDOI Listing
June 2017

Integration of Contrast-enhanced US into a Multimodality Approach to Imaging of Nodules in a Cirrhotic Liver: How I Do It.

Radiology 2017 Feb;282(2):317-331

From the Department of Radiology (P.C.J., S.R.W.) and Department of Medicine, Division of Gastroenterology (K.W.B., S.R.W.), Foothills Medical Centre, University of Calgary, 1403 29 St NW, Calgary, AB, Canada T2N 2T9; Department of Medical Imaging, Toronto General Hospital, University of Toronto, Toronto, Ont, Canada (H.J.J., T.K.K.); and Department of Imaging Research, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ont, Canada (P.N.B.).

Accurate characterization of cirrhotic nodules and early diagnosis of hepatocellular carcinoma (HCC) are of vital importance. Currently, computed tomography (CT) and magnetic resonance (MR) imaging are standard modalities for the investigation of new nodules found at surveillance ultrasonography (US). This article describes the successful integration of contrast material-enhanced US into a multimodality approach for diagnosis of HCC and its benefits in this population. The application of contrast-enhanced US immediately following surveillance US allows for prompt dynamic contrast-enhanced evaluation, removing the need for further imaging of benign lesions. Contrast-enhanced US also provides dynamic real-time assessment of tumor vascularity so that contrast enhancement can be identified regardless of its timing or duration, allowing for detection of arterial hypervascularity and portal venous washout. The purely intravascular nature of US contrast agents is valuable as the rapid washout of nonhepatocyte malignancies is highly contributory to their differentiation from HCC. The authors believe contrast-enhanced US provides complementary information to CT and MR imaging in the characterization of nodules in high-risk patients. RSNA, 2017 Online supplemental material is available for this article.
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http://dx.doi.org/10.1148/radiol.2016151732DOI Listing
February 2017

Contrast enhanced ultrasound (CEUS) in the prenatal evaluation of suspected invasive placenta percreta.

J Obstet Gynaecol Can 2016 10 23;38(10):975-978. Epub 2016 Aug 23.

Department of Obstetrics and Gynaecology, University of Toronto, Toronto ON; Department of Medical Biophysics and Sunnybrook Research Institute, Toronto ON.

Background: Morbidly adherent placentation now complicates approximately 1 in 500 pregnancies. Our group and others have demonstrated that antenatal diagnosis of invasive placentation and team-based delivery reduce severe morbidity. Ultrasound and magnetic resonance imaging (MRI) are both employed in the antenatal evaluation of pregnancies with suspected placenta increta/percreta. Accurate diagnosis in this context is essential to direct resources appropriately. Ultrasound methods, including colour and power Doppler, are the mainstays of screening at-risk women, whereas MRI is reserved for diagnostic purposes because of its cost and limited accessibility. In current practice, both methods are significantly limited by an inability to accurately define aberrant utero-placental blood flow, the definitive sign of deeply invasive placentation. We describe here an adjunctive method to define aberrant blood flow using ultrasound.

Case: We employed contrast-enhanced ultrasound (CEUS) in the antenatal evaluation of suspected extensive invasive placentation in a woman at 18 weeks' gestation. Invasive placentation was confirmed following hysterectomy.

Conclusion: CEUS, a technique that has been established as safe and well tolerated in the non-pregnant setting, has the potential to be deployed as a powerful adjunct to ultrasound to enhance both the screening and diagnostic components of care for women with suspected invasive placentation.
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http://dx.doi.org/10.1016/j.jogc.2016.06.012DOI Listing
October 2016

Detection of Early Tumor Response to Axitinib in Advanced Hepatocellular Carcinoma by Dynamic Contrast Enhanced Ultrasound.

Ultrasound Med Biol 2016 06 28;42(6):1303-11. Epub 2016 Mar 28.

Medical Imaging, University of Toronto, Toronto, ON, Canada. Electronic address:

This study aimed to evaluate the utility of dynamic contrast-enhanced ultrasound (DCE-US) in measuring early tumor response of advanced hepatocellular carcinoma to axitinib. Twenty patients were enrolled (aged 18-78 y; median 65). DCE-US was performed with bolus injection and infusion/disruption replenishment. Median overall survival was 7.1 mo (1.8-27.3) and progression free survival was 3.6 mo (1.8-17.4). Fifteen patients completed infusion scans and 12 completed bolus scans at 2 wk. Among the perfusion parameters, fractional blood volume at infusion (INFBV) decreased at 2 wk in 10/15 (16%-81% of baseline, mean 47%) and increased in 5/15 (116%-535%, mean 220%). This was not significantly associated with progression free survival (p = 0.310) or progression at 16 wk (p = 0.849), but was borderline statistically significant (p = 0.050) with overall survival, limited by a small sample size. DCE-US is potentially useful in measuring early tumor response of advanced hepatocellular carcinoma to axitinib, but a larger trial is needed.
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http://dx.doi.org/10.1016/j.ultrasmedbio.2016.01.025DOI Listing
June 2016