Publications by authors named "Grace M Y Ma"

4 Publications

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Neck CT imaging and correlation with thyroid cancer incidence across age, gender and race.

Clin Endocrinol (Oxf) 2021 Jan 5. Epub 2021 Jan 5.

Department of Radiology, Ohio State University Wexner Medical Center, Columbus, OH, USA.

Objective: Incidental detection of thyroid cancers has been proposed as a cause of thyroid cancer increases over past decades, but few studies assess the impact of imaging utilization on thyroid cancer incidence. This study quantifies neck CT prevalence and its relationship with thyroid cancer incidence as a function of age, sex and race.

Design And Patients: Medical records of over 1 million patients at our institution were retrospectively analysed to quantify neck CT prevalence from 2004 to 2011 (study period). A national cancer database was used to compute thyroid cancer incidences over the study period and a reference period (1974-81) and to calculate change in thyroid incidence between the two periods. Both populations were partitioned into demographic subgroups of varying age, sex and race. Linear correlation between neck imaging and thyroid cancer incidence changes among subgroups was assessed using Pearson's correlation.

Results: Neck CT imaging and change in thyroid cancer incidence varied across all examined demographic variables, particularly age. When stratifying by age, CT use correlated strongly with recent national thyroid cancer incidence (R = .97) and with 30-year change in thyroid cancer incidence (R = .87). Across all demographic subgroups, CT prevalence correlated strongly and positively with change in thyroid cancer incidence (R = .60), greater for whites (R = .60) and blacks (R = .70) than other races (R = .28).

Conclusion: Differences in neck CT usage strongly and positively correlates with the variation in thyroid cancer trends based on age, gender and race.
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January 2021

Hemodialysis Catheters in Infants: A Retrospective Single-Center Cohort Study.

J Vasc Interv Radiol 2020 05 15;31(5):778-786. Epub 2020 Apr 15.

Image Guided Therapy, Department of Medical Imaging, The Hospital for Sick Children, University of Toronto, 555 University Ave, Toronto, ON M5G 1X8, Canada.

Purpose: Evaluate technical aspects and outcomes of insertion/maintenance of hemodialysis (HD) central venous catheter (CVC) during infancy.

Materials And Methods: Single-center retrospective study of 29 infants who underwent 49 HD-CVC insertions between 2002 and 2016. Demographics, procedural, and post-procedural details, interventional radiology (IR) maintenance procedures, technical modifications, complications, and outcomes were evaluated. Technical adjustments during HD-CVC placement to adapt catheter length to patient size were labeled "modifications." CVCs requiring return visit to IR were called IR-maintenance procedures. Mean age and weight at HD-CVC insertion were 117 days and 4.9 kg.

Results: Of the 29 patients, 13 (45%) required renal-replacement-therapy (RRT) as neonates, 10 (34%) commenced RRT with peritoneal dialysis (PD), and 19 (66%) with HD. Fifteen nontunneled and 34 tunneled HD-CVCs were inserted while patients were ≤1 year. Technical modifications were required placing 25/49 (51%) HD-CVCs: 5/15 (33%) nontunneled and 20/34 (59%) tunneled catheters (P = .08). Patients underwent ≤6 dialysis-cycles/patient during infancy (mean 2.3), and a mean of 4.1 and 49 HD-sessions/catheter for nontunneled and tunneled HD-CVCs, respectively. Mean primary and secondary device service, and total access site intervals for tunneled HD-CVCs were 75, 115, and 201 days, respectively. A total of 26 of 49 (53%) patients required IR-maintenance procedures. Nontunneled lines had greater catheter-related bloodstream infections per 1,000 catheter-days than tunneled HD-CVCs (9.25 vs. 0.85/1,000 catheter days; P = .02). Nineteen patients (65%) survived over 1 year. At final evaluation (December 2017): 8/19 survived transplantation, 5/19 remained on RRT, 2/19 completely recovered, 1/19 lost to follow-up, and 3 died at 1.3, 2, and 10 years.

Conclusions: Placement/maintenance of HD-CVCs in infants pose specific challenges, requiring insertion modifications, and IR-maintenance procedures to maintain function.
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May 2020

Quantitative color-coded digital subtraction neuroangiography for pediatric arteriovenous shunting lesions.

Childs Nerv Syst 2019 12 6;35(12):2399-2403. Epub 2019 Jul 6.

Image Guided Therapy, Department of Diagnostic Imaging, Department of Medical Imaging, Hospital for Sick Children, University of Toronto, 555 University Ave, Toronto, ON, M5S, Canada.

Background: Several complex pediatric neurovascular conditions are amenable to endovascular treatment. Given the unique anatomical and physiological challenges in children, there is an ongoing need for tools and techniques that provide accurate information for treatment planning, while minimizing exposure to ionizing radiation and contrast. This is more so for neonates and infants with high-flow arteriovenous (AV) shunts that are challenging to assess using conventional techniques.

Objective: In this brief report, we describe, through representative cases, the potential role of quantitative color-coded digital subtraction angiography (qDSA) in neuroendovascular procedures in children with high-flow AV shunting lesions.

Methods: Images were obtained using an ArtisQ biplane system (Siemens Healthineers, Erlangen, Germany). Post-processing was performed at a dedicated workstation (Syngo, Siemens) using the iFlow module to generate color-coded maps of individual digital subtraction angiography runs.

Conclusion: Color-coded qDSA provides real-time quantitative information in high-flow AV shunting neurovascular lesions. This can potentially help direct treatment choices, optimize endovascular treatment protocols, monitor outcomes, and determine treatment end points.
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December 2019

Imaging of the Temporomandibular Joint in Juvenile Idiopathic Arthritis: How Does Quantitative Compare to Semiquantitative MRI Scoring?

J Oral Maxillofac Surg 2019 May 11;77(5):951-958. Epub 2018 Dec 11.

Assistant Professor, Department of Oral and Maxillofacial Surgery, Harvard School of Dental Medicine and Harvard Medical School, Boston, MA; Oral and Maxillofacial Surgeon, Department of Plastic and Oral Surgery, Boston Children's Hospital, Boston, MA. Electronic address:

Purpose: Contrast-enhanced magnetic resonance imaging (MRI) is commonly used to evaluate temporomandibular joint (TMJ) disease in patients with juvenile idiopathic arthritis (JIA). However, MRI assessments have been limited by qualitative reporting, the presence of enhancement in normal joints, and a lack of standardized protocols. The purpose of the present study was to compare a quantitative MRI analysis using an enhancement ratio (ER) to a new semiquantitative system developed by Outcome Measures in Rheumatology and Clinical Trials (OMERACT).

Materials And Methods: We performed a retrospective cross-sectional study of children with JIA who had undergone TMJ MRI with gadolinium enhancement at Boston Children's Hospital. The predictor variables were demographic data (sex, age at MRI) and disease-related findings (JIA subtype and arthritis medication at MRI). The outcome variables were OMERACT scores and ER (ratio of TMJ synovium and longus capitis muscle pixel intensities). The ER was compared with the OMERACT total, inflammatory, and damage scores using Pearson's correlation analysis and multivariable linear regression. Statistical significance was evaluated using the Student t test and analysis of variance with significance set at P < .05. Inter- and intraexaminer reliability were evaluated using intraclass correlation coefficients (ICCs).

Results: The sample included 50 subjects (84% female) with a mean age of 12.7 ± 3.9 years and 124 MRI scans. The mean ER was 2.5 ± 0.9 (normal, <1.55). The mean OMERACT total was 4.9 ± 3.3. Controlling for age, sex, JIA subtype, and medication, for every 1-U increase in ER, the OMERACT increased by 3.11 for the total (P < .001), 1.01 for the inflammatory (P < .001), and 0.86 for the damage (P < .001) scores. The intra- and interrater consistency was better for the ER (ICC, 0.83 and 0.96, respectively) than for OMERACT (ICC, 0.77 and 0.35, respectively).

Conclusions: Quantitative evaluation of TMJ synovial enhancement using the ER is easier to score and has superior intra- and interrater agreement; however, it can only assess inflammation. Semiquantitative assessment of TMJ using the OMERACT adds data about chronic changes. Using both systems might provide the most accurate assessment of JIA status.
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May 2019