Silvia D Chang

Silvia D Chang
University of British Columbia | UBC · Department of Radiology

MD FRCPC FSAR

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193
Publications
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Publications

Publications (193)
Article
The standard of care for prostate cancer (PCa) diagnosis is the histopathological analysis of tissue samples obtained via transrectal ultrasound (TRUS) guided biopsy. Models built with deep neural networks (DNNs) hold the potential for direct PCa detection from TRUS, which allows targeted biopsy and subsequently enhances outcomes. Yet, there are on...
Article
Multiparametric MRI (mpMRI), interpreted using PI-RADS, improves the initial detection of clinically significant prostate cancer (PCa). Prostate MR image quality has increasingly recognized relevance to the use of mpMRI for PCa diagnosis. Additionally, mpMRI is increasingly used in scenarios beyond initial detection, including active surveillance a...
Article
Full-text available
Objective: To elucidate the use of radiological studies, including nuclear medicine, and biopsy for the diagnosis and staging of prostate cancer (PCA) in clinical practice and understand the current status of PCA in Asian countries via an international survey. Materials and methods: The Asian Prostate Imaging Working Group designed a survey ques...
Article
Full-text available
Background: Adrenal washout CT is not useful for evaluating incidental adrenal masses in patients without known or suspected primary extra-adrenal malignancy. Objectives: To evaluate the diagnostic utility of adrenal mass biopsy (AMB) in patients without known or suspected extra-adrenal primary malignancy. Methods: This retrospective six-center stu...
Article
Full-text available
Purpose: The Canadian Association of Radiologists (CAR) Endometriosis Working Group developed a national survey to evaluate current practice patterns associated with imaging endometriosis using advanced pelvic ultrasound and MRI to inform forthcoming clinical practice guidelines for endometriosis imaging. Methods: The anonymous survey consisted of...
Article
Renal cell carcinoma is a complex group of highly heterogenous renal tumors demonstrating variable biological behavior. Pretreatment imaging of renal cell carcinoma involves accurate assessment of the primary tumor, presence of nodal, and distant metastases. CT and MRI are the key imaging modalities used in the staging of renal cell carcinoma. Impo...
Article
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The Canadian Association of Radiologists (CAR) Endometriosis Working Group was tasked with providing guidance and benchmarks to ensure the quality of technique and interpretation for advanced imaging modalities associated with diagnosing endometriosis. This practice statement provides an overview of the state of the art of advanced pelvic ultrasoun...
Article
Ultrasound imaging is commonly used to guide sampling the prostate tissue in transrectal biopsies, followed by detection of cancer through histopathological analysis and coarse labelling of sampled tissue. Ideally, the procedure should be improved by developing machine learning solutions that can identify the presence of cancer in ultrasound images...
Article
Prostate cancer is the most common malignancy and the third most common cause of death in Canadian men. In light of evolving diagnostic pathways for prostate cancer and the increased use of MRI, which now includes its use in men prior to biopsy, the Canadian Association of Radiologists established a Prostate MRI Working Group to produce a white pap...
Article
Purpose: Ultrasound is the standard-of-care to guide the systematic biopsy of the prostate. During the biopsy procedure, up to 12 biopsy cores are randomly sampled from six zones within the prostate, where the histopathology of those cores is used to determine the presence and grade of the cancer. Histopathology reports only provide statistical in...
Article
Full-text available
Purpose: Ultrasound-guided biopsy plays a major role in prostate cancer (PCa) detection, yet is limited by a high rate of false negatives and low diagnostic yield of the current systematic, non-targeted approaches. Developing machine learning models for accurately identifying cancerous tissue in ultrasound would help sample tissues from regions wi...
Article
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Purpose This study evaluates the impact of second-opinion review of multiparametric prostate MRI for cancer detection by a multidisciplinary review board at a tertiary care center when compared with the initial community radiologist interpretation. Methods Cases were collected retrospectively from multidisciplinary prostate MRI rounds from 2017 to...
Article
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Background Immunoglobulin G4-related disease (IgG4-RD) is a systemic lymphoproliferative disorder characterized by elevated serum IgG4 levels and tumefactive lesions that can involve nearly every organ system. Involvement of the prostate is rare but has been reported in limited cases. Case presentation A 28-year-old man of Asian descent with a his...
Article
PurposeSystematic prostate biopsy is widely used for cancer diagnosis. The procedure is blind to underlying prostate tissue micro-structure; hence, it can lead to a high rate of false negatives. Development of a machine-learning model that can reliably identify suspicious cancer regions is highly desirable. However, the models proposed to-date do n...
Chapter
Motivation: Accurate detection of prostate cancer using ultrasound data is a challenging yet highly relevant clinical question. A significant roadblock for training accurate models for cancer detection is the lack of histopathology labels with high resolution that correspond to the presence of cancer in the entire imaging or biopsy planes. Histopat...
Article
Full-text available
Background IgG4-related disease (IgG4-RD) is an immune-mediated disease that may present as a tumefactive lesion in nearly any organ. These mass lesions often resemble malignancy both clinically and radiologically, and some patients undergo surgical resection which could possibly be avoided with early recognition of IgG4-RD. We performed a retrospe...
Article
Full-text available
Transarterial radioembolization with yttrium-90 microspheres is an established therapy for hepatocellular carcinoma. Post-procedural imaging is important for the assessment of both treatment response and procedural complications. A variety of challenging treatment-specific imaging phenomena complicate imaging assessment, such as changes in tumoral...
Article
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Stereotactic body radiation therapy (SBRT) is an emerging locoregional treatment (LRT) modality used in the management of patients with hepatocellular carcinoma (HCC). The decision to treat HCC with LRT is evaluated in a multidisciplinary setting, and the specific LRT chosen depends on the treatment intent, such as bridge-to-transplant, down-stagin...
Article
Contrast-enhanced MR imaging plays an important role in the evaluation of patients with chronic liver disease, particularly for detection and characterization of liver lesions. The two most commonly used contrast agents for liver MR imaging are extracellular agents (ECAs) and hepatobiliary agents (HBAs). In patients with liver disease, the main adv...
Article
Full-text available
Prostate cancer is the second most common malignancy in men worldwide. Systematic transrectal prostate biopsy is commonly used to obtain tissue to establish the diagnosis. However, in recent years, MRI-targeted biopsy (based on an MRI examination performed prior to consideration of biopsy) has been shown to detect more clinically significant cancer...
Article
The Coronavirus disease 2019 (COVID-19) pandemic has significantly affected health care systems throughout the world. A Qualtrics survey was targeted for radiologists around the world to study its effect on the operations of prostate MRI studies and biopsies. Descriptive statistics were reported. A total of 60 complete responses from five continent...
Article
OBJECTIVE. The purpose of this study was to report on the practice patterns and challenges of performing and interpreting prostate MRI. SUBJECTS AND METHODS. An electronic survey regarding prostate MRI practice patterns and challenges was sent to members of the Society of Abdominal Radiology. RESULTS. The response rate was 15% (212/1446). Most (65%...
Article
Full-text available
Artificial intelligence is a technique that holds promise for helping radiologists improve the care of our patients. At the same time, implementation decisions we make now can have a long-lasting effect on patient outcomes. In the following article, we discuss four areas with unique considerations for implementation of AI: bias, trust, risk, and de...
Chapter
Ultrasound is a common imaging modality used for targeting suspected cancerous tissue in prostate biopsy. Since ultrasound images have very low specificity and sensitivity for visualizing the cancer foci, a significant body of literature have aimed to develop ultrasound tissue characterization solutions to alleviate this issue. Major challenges are...
Article
Background Gender disparity exists in nearly every medical specialty, particularly in leadership roles and academia. Radiology is not exempt from this phenomenon, with women making up less than a third of radiology residents in the United States (US). This can have long-lasting effects on the career progression of female radiologists. Our search di...
Preprint
Full-text available
Background: IgG4-related disease is an immune-mediated disease that may present as a tumefactive lesion in nearly any organ. These mass lesions often resemble malignancy both clinically and radiologically, and some patients undergo unnecessary surgical resection. We performed a retrospective single center study examining how many patients with IgG4...
Article
Full-text available
Background: Retroperitoneal fibrosis (RPF) is characterized by the proliferation of fibrous tissue in the retroperitoneum. The majority of RPF cases are due to idiopathic or IgG4-related disease. Recent studies on IgG4-related disease have shown rituximab to be an effective treatment. The current first-line treatment for idiopathic RPF (iRPF) is g...
Article
PurposeUltrasound imaging is routinely used in prostate biopsy, which involves obtaining prostate tissue samples using a systematic, yet, non-targeted approach. This approach is blinded to individual patient intraprostatic pathology, and unfortunately, has a high rate of false negatives.Methods In this paper, we propose a deep network for improved...
Article
Background Prostate MRI is used widely in clinical care for guiding tissue sampling, active surveillance, and staging. The Prostate Imaging Reporting and Data System (PI-RADS) helps provide a standardized probabilistic approach for identifying clinically significant prostate cancer. Despite widespread use, the variability in performance of prostate...
Article
OBJECTIVE. The purpose of this article is to prospectively compare image quality and diagnostic accuracy of clinically significant prostate cancer with and without endorectal coil (ERC) at 3 T using a combination of T2-weighted and diffusion-weighted MRI. SUBJECTS AND METHODS. Twenty-three patients with biopsy-proven prostate cancer underwent MRI w...
Article
We propose an image guidance system for robot assisted laparoscopic radical prostatectomy (RALRP). A virtual 3D reconstruction of the surgery scene is displayed underneath the endoscope's feed on the surgeon's console. This scene consists of an annotated preoperative Magnetic Resonance Image (MRI) registered to intraoperative 3D Trans-rectal Ultras...
Article
Purpose: To determine medical students' and radiologists' attitude toward radiology electives at a distributed medical school and identify specific areas for improvement. Methods: During a single academic year, both students and faculty preceptors were surveyed anonymously following a senior radiology elective. The survey was based on an establi...
Article
Multiparametric magnetic resonance imaging (MRI) of the prostate is a powerful and increasingly utilized imaging study for the diagnosis, staging, and surveillance of prostate cancer. With greater adoption by clinicians, it is becoming more common for incidental findings to be first detected on prostate MRI. Inadequate description of clinically sig...
Article
Full-text available
Purpose: To evaluate the role of virtual monoenergetic imaging (VMI) in the detection of peritoneal metastatic disease in contrast-enhanced computed tomography (CT) of the abdomen and pelvis and to compare this technique to the conventional 120 kV mixed dataset. Materials and methods: Institutional review board approval was obtained with no info...
Article
Luminal water imaging (LWI) is a new MRI T2 mapping technique that has been developed with the aim of diagnosis of prostate carcinoma (PCa). This technique measures the fractional amount of luminal water in prostate tissue, and has shown promising preliminary results in detection of PCa. To include LWI in clinical settings, further investigation on...
Article
Rationale and Aim As medical schools reduce the hours of anatomy teaching, residents in anatomy-intensive residency programs like radiology must independently acquire the anatomy knowledge needed to achieve competency. The purpose of this study was to develop and evaluate a 4-week competency-based self-directed anatomy rotation for junior residents...
Article
Introduction: The natural history of prostatic lesions identified on multiparametric magnetic resonance imaging (mpMRI) is largely unknown. We aimed to describe changes observed over time on serial MRI. Methods: All patients with ≥2 MRI studies between 2008 and 2015 at our institution were identified. MRI progression was defined as an increase i...
Article
Full-text available
Purpose Emergency Departments (ED) are becoming busier, with a resultant increase in the number of imaging referrals. The purpose of this study was to assess the diagnostic accuracy of an abbreviated two sequence magnetic resonance (MR) protocol for evaluating ED patients with right lower quadrant pain and suspected acute appendicitis, with a view...
Article
Aims To define standard criteria for the detection of lipohypertrophy using ultrasonography and to determine the accuracy of this method. Method Individuals using insulin therapy for ≥2 years with unknown lipohypertrophy status were enrolled at a diabetes education centre. A team of diabetes educator nurses performed a clinical examination for evi...
Article
Introduction: The natural history of prostatic lesions identified on multiparametric magnetic resonance imaging (mpMRI) is largely unknown. We aimed to describe changes observed over time on serial MRI. Methods: All patients with ≥2 MRI studies between 2008 and 2015 at our institution were identified. MRI progression was defined as an increase i...
Article
Rationale and objectives: Recently, the relevance of the postgraduate year 1 (PGY-1) Basic Clinical Year for radiology residents has been questioned. The purpose of this study was to determine the attitude of radiologists and trainees toward this year and which clinical rotations they perceived as most valuable to clinical practice. Materials and...
Article
The purpose of this study was to evaluate the utility of dynamic contrast-enhanced magnetic resonance imaging (DCE MRI) in the detection of dominant prostate tumors with multi-parametric MRI of the whole gland. Combined diffusion tensor imaging (DTI) and DCE MRI from 16 patients with biopsy-proven prostate cancer and no previous treatment were acqu...
Article
Full-text available
Background Senior medical students represent future physicians who commonly refer patients for diagnostic imaging studies that may involve ionizing radiation. The radiology curriculum at the University of British Columbia provides students with broad-based knowledge about common imaging examinations. The purpose of this study was to investigate stu...
Article
Objective: Neurocutaneous syndromes are a heterogeneous group of multisystemic disorders. We review the multimodality imaging findings in the disorders with a propensity for intraabdominal disease. We highlight more recently recognized disease patterns and discuss imaging surveillance optimization. Conclusion: Knowledge of varied intraabdominal...
Article
Magnetic resonance imaging (MRI) has a well-established role as a highly specific and accurate modality for characterizing benign and malignant focal liver lesions. In particular, contrast-enhanced MRI using hepatocyte-specific contrast agents (HSCAs) improves lesion detection and characterization compared to other imaging modalities and MRI techni...
Article
Full-text available
Purpose: To evaluate the feasibility and to report the early outcomes of focal treatment of prostate cancer using low- dose-rate brachytherapy (LDR-PB). Material and methods: Seventeen patients were screened with multi-parametric magnetic resonance imaging (mpMRI), 14 of whom proceeded to receive trans-perineal template mapping biopsy (TTMB). Foca...
Article
Burkitt's lymphoma is a highly aggressive non-Hodgkin's B-cell lymphoma, which often presents with intra-abdominal involvement. The purpose of this pictorial review is to illustrate the various intra-abdominal imaging findings of Burkitt's lymphoma. Extranodal disease at presentation is common, including involvement of the bowel, stomach, pancreas,...
Article
Purpose To assess the feasibility of luminal water imaging, a quantitative T2-based magnetic resonance (MR) imaging technique, for the detection and grading of prostate cancer (PCa). Materials and Methods Eighteen patients with biopsy-proven PCa provided informed consent to be included in this institutional human ethics board-approved prospective s...
Article
In this article, we discuss the importance of mentorship in Radiology and more specifically mentorship in Radiology research to help ensure the advancement of our specialty. We also describe how research mentorship is conducted at our institution.
Article
Purpose: To determine the relationship between parameters measured from luminal water imaging (LWI), a new magnetic resonance imaging (MRI) T2 mapping technique, and the corresponding tissue composition in prostate. Materials and methods: In all, 17 patients with prostate cancer were examined with a 3D multiecho spin echo sequence at 3T prior to...
Conference Paper
PURPOSE To evaluate the role of iodine quantification in differentiating colonic diverticulitis from colonic adenocarcinoma. METHOD AND MATERIALS Institutional review board approval was obtained, with no informed consent required, for this retrospective analysis. 146 consecutive patients with acute diverticulitis were scanned using a standard prot...
Poster
PURPOSE To evaluate the role of virtual monochromatic imaging (VMI) in the detection of peritoneal metastatic disease in contrast-enhanced computed tomography (CT) of the abdomen and pelvis and to compare this technique to conventional polychromatic imaging (PCI). METHOD AND MATERIALS Institutional review board approval was obtained, with no inform...
Article
Full-text available
DCE MRI is an established component of multi-parametric MRI of the prostate. The sequence highlights the vascularization of cancerous lesions, allowing readers to corroborate suspicious findings on T2W and DW MRI and to note subtle lesions not visible on the other sequences. In this article, we review the technical aspects, methods of evaluation, l...
Article
Rationale and objectives: In order to ease the transition from internship to diagnostic radiology residency, a year-long didactic introduction to radiology course was offered to post-graduate year one (PGY-1) diagnostic radiology residents during their internship, which consisted of 27 hours of lecture over 9 months. The purpose of this study was...
Poster
Full-text available
Learning objectives: Following review of this poster, it is hoped that the reviewer will have achieved the following: 1. To become familiar with the Liver Imaging Reporting and Data Systems (LI-RADS) classification and its updated version v2014. 2. To use a stepwise approach to the classification of liver lesions using the LI-RADS classification sy...
Article
Purpose: In patients with small bowel obstruction (SBO), it is challenging to detect early ischemia. The purpose of this study is to evaluate the quantitative and qualitative benefits of virtual monoenergetic image (VMI) reconstruction in the assessment of small bowel mural enhancement on dual source dual energy computed tomography (CT) scans of t...
Article
The characterization and management of focal liver lesions is a commonly encountered problem in radiology. While the imaging findings will often be diagnostic, in equivocal cases the decision of how to proceed may be challenging. The primary modalities for liver lesion characterization are multiphase contrast-enhanced computed tomography and magnet...
Article
A 66-year-old man was referred for urological evaluation for an abnormal digital rectal exam (cT2a, subtle nodule at left base, 121 cc prostate) and an elevated prostate specific antigen (PSA) of 8.0 ng/ml. Subsequent 12-core transrectal ultrasound (TRUS)-guided biopsy revealed Gleason 3+4 adenocarcinoma in seven of 12 cores, including all six core...
Article
Full-text available
A common challenge when performing surface-based registration of images is ensuring that the surfaces accurately represent consistent anatomical boundaries. Image segmentation may be difficult in some regions due to either poor contrast, low slice resolution, or tissue ambiguities. To address this, we present a novel non-rigid surface registration...
Conference Paper
We present a 2D to 3D registration framework that compensates for prostate motion and deformations during freehand prostate biopsies. It has two major components: 1) a trajectory-based rigid registration to account for gross motions of the prostate; and 2) a non-rigid registration constrained by a finite element model (FEM) to adjust for residual m...
Article
Objectives: Easily palpable splenomegaly can be identified on physical examination, but it is difficult to detect lesser degrees of splenomegaly. Rapid bedside assessment can be conducted with hand-carried ultrasound. We performed this study to determine whether medical residents could reliably assess spleen size using hand-carried ultrasound afte...
Article
Full-text available
Primary retroperitoneal masses include a diverse, and often rare, group of neoplastic and non-neoplastic entities that arise within the retroperitoneum but do not originate from any retroperitoneal organ. Their overlapping appearances on cross-sectional imaging may pose a diagnostic challenge to the radiologist; familiarity with characteristic imag...
Article
A common challenge when performing surfacebased registration of images is ensuring that the surfaces accurately represent consistent anatomical boundaries. Image segmentation may be difficult in some regions due to either poor contrast, low slice resolution, or tissue ambiguities. To address this, we present a novel non-rigid surface registration m...
Article
Full-text available
In surface-based registration for image-guided interventions, the presence of missing data can be a significant issue. This often arises with real-time imaging modalities such as ultrasound, where poor contrast can make tissue boundaries difficult to distinguish from surrounding tissue. Missing data poses two challenges: ambiguity in establishing c...