Publications by authors named "Lee Chau"

BackgroundWith increasing importance of iodine-based contrast media (ICM) in radiology, a label of allergy to ICM has significant impact on patient management, and objective testing for ICM allergy can help guide subsequent administration.PurposeTo correlate skin testing with drug provocation test (DPT) outcomes and determine cross-reactivity between our institution's three available ICMs.Material and MethodsEligible patients who presented to our institution's radiology department within a 3-year period with suspected ICM allergy were referred to the allergist for evaluation with skin testing ± DPT.

View Article and Find Full Text PDF

Manual annotation of ultrasound images relies on expert knowledge and requires significant time and financial resources. Semi-supervised learning (SSL) exploits large amounts of unlabeled data to improve model performance under limited labeled data. However, it faces two challenges: fusion of contextual information at multiple scales and bias of spatial information between multiple objects.

View Article and Find Full Text PDF

Introduction: Cancer rates for Prostate Imaging-Reporting and Data System (PI-RADS) 3 lesions are low. We aimed to determine the clinical and magnetic resonance imaging (MRI) parameters that can provide risk stratification for PI-RADS 3 transition zone (TZ) lesions to guide decision for biopsy, which can improve the cost-effectiveness of resource utilisation.

Methods: The MRI scans of all patients who underwent MRI-ultrasound fusion targeted biopsy from 1 May 2016 to 31 December 2022 were retrospectively assessed by two board-certified abdominal radiologists.

View Article and Find Full Text PDF

While computer vision has proven valuable for medical image segmentation, its application faces challenges such as limited dataset sizes and the complexity of effectively leveraging unlabeled images. To address these challenges, we present a novel semi-supervised, consistency-based approach termed the data-efficient medical segmenter (DEMS). The DEMS features an encoder-decoder architecture and incorporates the developed online automatic augmenter (OAA) and residual robustness enhancement (RRE) blocks.

View Article and Find Full Text PDF

Background: Surveillance of pancreatic cysts are necessary due to risk of malignant transformation. However, reported progression rates to advanced neoplasia are variable and the high frequency of surveillance scans may pose a considerable burden on healthcare resources.

Purpose: To validate the effectiveness of the Fukuoka Guidelines surveillance regime and determine if a longer surveillance interval can be established.

View Article and Find Full Text PDF

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 questionnaire with four domains focused on prostate magnetic resonance imaging (MRI), other prostate imaging, prostate biopsy, and PCA backgrounds. The questionnaire was sent to 111 members of professional affiliations in Korea, Japan, Singapore, and Taiwan who were representatives of their working hospitals, and their responses were analyzed.

View Article and Find Full Text PDF

Medical Ultrasound (US) is one of the most widely used imaging modalities in clinical practice, but its usage presents unique challenges such as variable imaging quality. Deep Learning (DL) models can serve as advanced medical US image analysis tools, but their performance is greatly limited by the scarcity of large datasets. To solve the common data shortage, we develop GSDA, a Generative Adversarial Network (GAN)-based semi-supervised data augmentation method.

View Article and Find Full Text PDF

The transformer is primarily used in the field of natural language processing. Recently, it has been adopted and shows promise in the computer vision (CV) field. Medical image analysis (MIA), as a critical branch of CV, also greatly benefits from this state-of-the-art technique.

View Article and Find Full Text PDF

Introduction: In collaboration with the Department of Rheumatology, Allergy and Immunology, our study aims to review the outcomes of and propose an improved workflow for the management of patients with prior hypersensitivity reactions to iodinated contrast media (ICM).

Method: Outpatients coming for contrast-enhanced computed tomography (CECT) were stratified into 3 categories (definite, unconfirmed and inaccurate) based on likelihood of their contrast hypersensitivity label. Patients could be offered a different ICM, receive the same ICM, or be referred to an allergist for further evaluation.

View Article and Find Full Text PDF

Portal vein thrombosis (PVT) is usually diagnosed on contrast-enhanced CT, MRI or Doppler ultrasound. However, for patients with contraindications to intravenous contrast, its diagnosis is challenging. In these patients, PVT can be detected on unenhanced MRI using T2, T1 and diffusion-weighted imaging.

View Article and Find Full Text PDF

Magnetic resonance imaging (MRI)-targeted prostate biopsy is the recommended investigation in men with suspicious lesion(s) on MRI. The role of concurrent systematic in addition to targeted biopsies is currently unclear. Using our prospectively maintained database, we identified men with at least one Prostate Imaging-Reporting and Data System (PI-RADS) ≥3 lesion who underwent targeted and/or systematic biopsies from May 2016 to May 2020.

View Article and Find Full Text PDF

Advances in our understanding of the role of magnetic resonance imaging (MRI) for the detection of prostate cancer have enabled its integration into clinical routines in the past two decades. The Prostate Imaging Reporting and Data System (PI-RADS) is an established imaging-based scoring system that scores the probability of clinically significant prostate cancer on MRI to guide management. Image fusion technology allows one to combine the superior soft tissue contrast resolution of MRI, with real-time anatomical depiction using ultrasound or computed tomography.

View Article and Find Full Text PDF

Introduction: Ultrasonography (US) is the current standard of care for imaging surveillance in patients at risk of hepatocellular carcinoma (HCC). Magnetic resonance imaging (MRI) has been explored as an alternative, given the higher sensitivity of MRI, although this comes at a higher cost. We performed a cost-effective analysis comparing US and dual-sequence non-contrast-enhanced MRI (NCEMRI) for HCC surveillance in the local setting.

View Article and Find Full Text PDF

Objectives: To perform a systematic review and meta-analysis comparing diagnostic performance and inter reader agreement between PI-RADS v. 2.1 and PI-RADS v.

View Article and Find Full Text PDF

MRI has become important for the detection of prostate cancer. MRI-guided biopsy is superior to conventional systematic biopsy in patients suspected with prostate cancer. MRI is also increasingly used for monitoring patients with low-risk prostate cancer during active surveillance.

View Article and Find Full Text PDF
Article Synopsis
  • The study is a retrospective cohort analysis conducted to assess the effectiveness of conventionally-fractionated external beam radiation therapy (cEBRT) for treating spinal metastases in prostate cancer patients from 2008 to 2018.
  • Results show that cEBRT led to a median local progression-free survival of 7.8 months and an overall survival of 9.0 months, with significant pain relief experienced by the majority of patients.
  • Factors such as better performance status, castration-sensitive disease, prior spinal surgery, and use of novel antiandrogen treatments were linked to improved survival outcomes, suggesting a need for more aggressive treatment in certain patient groups.
View Article and Find Full Text PDF

Aim: To compare the latest 2019 version of Bosniak classification (BCnew) against Bosniak classification prior to 2019 (BCold) using contrast-enhanced ultrasound (CEUS) and to compare CEUS against contrast-enhanced CT (CECT) based on BCnew.

Material And Methods: Patients who had both CEUS and CECT of the kidneys performed within three months of each other were included. CECT and CEUS images of renal cysts were retrospectively analysed by two independent readers using BCnew, extrapolating the BCnew criteria to CEUS.

View Article and Find Full Text PDF
Article Synopsis
  • Researchers studied the effectiveness of combining T2-weighted imaging with T2-mapping in detecting prostate cancer in 40 patients, comparing this method to standard T2-weighted imaging.
  • They found that while there was only a slight improvement in reader agreement and overall diagnostic accuracy, the combination method significantly increased sensitivity for detecting malignancy from 49.2% to 73.0%.
  • Despite the higher sensitivity, the combined method produced slightly lower specificity, meaning it could lead to more false positives, but both techniques had comparable predictive values for diagnosing prostate cancer.
View Article and Find Full Text PDF

Introduction: This study aimed to evaluate the potential of non-contrast-enhanced magnetic resonance (MR) imaging as an imaging surveillance tool for detection of hepatocellular carcinoma (HCC) in at-risk patients and to compare the performance of non-contrast MR imaging with ultrasonography (US) as a screening modality for the same.

Methods: In this retrospective study, patients diagnosed with HCC between 1 January 2010 and 31 December 2015 were selected from our institution's cancer registry. Patients who underwent MR imaging and had US performed within three months of the MR imaging were included.

View Article and Find Full Text PDF
Article Synopsis
  • The study aimed to evaluate if MRI size cut-offs can effectively identify clinically significant prostate cancer (csPCA), focusing on improving existing criteria in PI-RADS.
  • MRIs from 293 patients were analyzed, with tumors measured from different zones and correlated with their Gleason grades; 309 lesions were examined.
  • Results indicated that lesion size has a stronger association with clinically significant cancer in the peripheral zone (PZ) than in the transition zone (TZ), suggesting size cut-offs of 14 mm for PZ and 21 mm for TZ to better differentiate between cancer severities.
View Article and Find Full Text PDF