Publications by authors named "Helen M C Cheung"

Introduction: Contrast-enhanced MRI is routinely performed as part of preoperative work-up for patients with Colorectal Cancer Liver Metastases (CRLM). Radiomic biomarkers depicting the characteristics of CRLMs in MRI have been associated with overall survival (OS) of patients, but the reproducibility and clinical applicability of these biomarkers are limited due to the variations in MRI protocols between hospitals.

Methods: In this work, we propose a generalizable radiomic model for predicting OS of CRLM patients who received preoperative chemotherapy and delayed-phase contrast enhanced (DPCE) MRIs prior to hepatic resection.

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The coronavirus disease 2019 (COVID-19) pandemic has reduced radiology volumes across the country as providers have decreased elective care to minimize the spread of infection and free up health care delivery system capacity. After the stay-at-home order was issued in our county, imaging volumes at our institution decreased to approximately 46% of baseline volumes, similar to the experience of other radiology practices. Given the substantial differences in severity and timing of the disease in different geographic regions, estimating resumption of radiology volumes will be one of the next major challenges for radiology practices.

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Purpose: Late gadolinium hyperintensity (LGH) is sometimes seen in colorectal liver metastasis (CRLM) and represents a significant diagnostic pitfall due to overlap with LGH in benign hemangiomas; therefore, the objective of this study was to determine the prevalence of LGH and the ability of LGH to differentiate between CRLM and benign lesions with intravascular (gadofosveset) vs extracellular contrast agents (gadobutrol).

Methods: Patients with known colorectal cancer and suspected liver lesions were prospectively recruited into this institutional review board-approved, single institution study and received magnetic resonance imaging of the liver with gadofosveset and gadobutrol. The prevalence of LGH for CRLMs and solid benign lesions was determined.

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Previous studies have demonstrated that target tumor enhancement (TTE) of colorectal cancer liver metastases (CRCLM) on 10-minute delayed phase gadobutrol-enhanced MRI is associated with overall survival post-hepatectomy. The purpose of this study was to determine whether TTE of CRCLM on preoperative gadobutrol-enhanced MRI measured at 5-minute delayed phase is also associated with overall survival. We performed a single-institution, REB-approved, retrospective study of 121 patients with CRCLM who had received a clinical gadobutrol-enhanced MRI after treatment with chemotherapy and prior to liver surgery between January 1, 2006 and December 31, 2012.

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Purpose: To determine if late gadolinium MRI enhancement of colorectal liver metastases (CRCLM) is associated with overall survival among nonsurgical patients.

Materials And Methods: This retrospective study was approved by the institutional research ethics board. Late gadolinium enhancement was measured using target tumour enhancement (TTE) in all nonsurgical patients with CRCLM who received a 10-min delayed phase gadobutrol-enhanced liver MRI between March 1, 2006, and August 31, 2014.

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Objectives: To determine whether tumour enhancement on preoperative delayed-phase gadoxetate-enhanced MRI can predict long-term survival in patients with colorectal liver metastases (CRCLM) post-hepatectomy.

Materials And Methods: Sixty-five patients who received a preoperative gadoxetate-enhanced MRI prior to liver resection for CRCLM from January 1, 2010, to December 31, 2012, were included in this retrospective study. Target tumour enhancement (TuEn) was calculated as the mean percentage increase in SNR from precontrast to 10-min or 20-min delayed phase for up to two target lesions.

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Purpose: To determine whether late gadolinium MRI enhancement of colorectal liver metastases (CRCLM) post-chemotherapy is associated with tumour fibrosis and survival post-hepatectomy.

Materials And Methods: The institutional review board approved this retrospective cohort study and waived the requirement for informed consent. A cohort of 121 surgical patients who received preoperative MRI after chemotherapy between 2006-2012 was included in this study.

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Purpose: To determine if complicated plaque can be found by using magnetic resonance (MR) imaging-depicted intraplaque hemorrhage (IPH), even among symptomatic patients with low-grade (≤50%) carotid stenosis.

Materials And Methods: The institutional ethics review board approved this retrospective study and waived requirements for written informed consent. Symptomatic patients with bilateral 0%-50% carotid stenosis referred for carotid MR imaging were considered.

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Purpose: We recently showed that the quaternary lidocaine derivative, QX-314, produces long-lasting local anesthesia with a slow onset in animal models in vivo. As quaternary agents do not rapidly penetrate biological membranes or the blood-brain barrier, QX-314 may represent a local anesthetic with decreased systemic toxicity compared with conventional tertiary aminoamines. To test this hypothesis, we conducted an in vivo animal study in mice to compare QX-314 with lidocaine in terms of its relative central nervous system (CNS) and cardiac toxicity.

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Background: We recently found that peripheral administration of the quaternary lidocaine derivative, QX-314, produces long-lasting sensory and motor blockade in animals. The goal of this study was to test whether intrathecal QX-314 has similar properties.

Methods: We conducted a randomized, double-controlled, blinded study with female CD-1 mice.

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