Terence S Hong

SickKids, Toronto, Ontario, Canada

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Publications (8)6.26 Total impact

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    ABSTRACT: PURPOSE To establish an optimized abdominal MR protocol based on image quality and overall scan time on healthy pediatric volunteers that could be implemented and evaluated in the clinical setting METHOD AND MATERIALS Institutional review board approval, a “Trainee Start-Up Fund” (Hospital for Sick Children), and informed consent was obtained prior to imaging. The study included 9 healthy pediatric volunteers (M=6, F=3, Avg Age=12.4 y, Age Range=8-17 y) who underwent an abdominal MR without sedation (1.5 T). No oral or IV contrast was administered. Each volunteer was imaged using 9 sequences – coronal (cor) HASTE, cor T1 TSE, cor VIBE FS, cor TruFISP, axial (ax) T1 FLASH, ax T1 TSE, ax TruFISP, ax T2 TSE FS, ax T2 FS BLADE, and ax DWI. Four experienced radiologists each independently reviewed images for quality and the presence of various artifacts (Likert scale: 1-5, non-diagnostic to excellent). Scan times of each sequence were recorded. Kendall’s Coefficient of Concordance (W) was used to assess interobserver agreement. RESULTS Image quality was greatest in cor HASTE and ax T1 TSE and lowest in ax DWI. Among the sequences with the highest image quality, only ax/ cor TruFISP, cor VIBE FS, ax T1 in-/opp. phase, cor HASTE, ax pelvic T1 TSE and ax pelvic T2 FS +/-BLADE had scan times less than 3 minutes each. Except for coronal TruFISP images, interobserver agreement of image quality was high for all sequences (W range=0.5-0.83, p>0.05). Overall, artifact was lowest in cor HASTE and greatest in ax DWI. However, there were no sequences in which average artifact resulted in non-diagnostic images. Cardiac/breathing/motion artifact, which was greatest in ax T2 TSE FS and ax DWI, accounted for the highest degrees of artifact. Interobserver agreement varied depending on sequence and type of artifact (W range=0.16-0.71). CONCLUSION Except for ax DWI, all sequences investigated in this study produced diagnostic quality images. With consideration to image quality, associated artifact, and scan time, we recommend cor HASTE, ax/ cor TruFISP, ax T2 FS BLADE and ax pelvic T1 TSE to be essential sequences in pediatric abdominal MR. CLINICAL RELEVANCE/APPLICATION The recommended sequences should be implemented in the clinical setting and assessed for feasibility and reliability.
    Radiological Society of North America 2011 Scientific Assembly and Annual Meeting; 11/2011
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    ABSTRACT: Radiological assessment of vasculopathy in children is typically undertaken with ultrasonography, echocardiography, conventional angiography, computed tomography and, more recently, positron emission tomography. Drawbacks of these modalities include radiation exposure or, in the case of ultrasonography, the dependence on operator skills and sufficient acoustic windows. With advancements in MR technology, which have improved sensitivity and shortened scan times, whole-body magnetic resonance angiography (WB-MRA) lends itself as a potential "one-stop shop" for vascular imaging. Currently, WB-MRA is primarily used in adult patients with atherosclerosis or multifocal regional vasculopathy. WB-MRA has not been employed in the routine assessment of pediatric vascular disease. The purpose of this article is to describe and illustrate our WB-MRA imaging technique for evaluation of pediatric vasculopathy.
    Pediatric Radiology 01/2011; 41(6):769-78. · 1.57 Impact Factor
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    ABSTRACT: Studies have reported that thoracic CT may provide greater sensitivity compared with radiography in detection of pediatric rib fractures and fracture healing. The additional sensitivity afforded by thoracic CT may have medicolegal implications where abuse is suspected. To determine the additional value of postmortem thoracic CT compared with radiography in detecting pediatric rib fractures, and fracture healing, using autopsy findings as a gold standard. We retrospectively reviewed 56 coroner's cases with postmortem radiography and CT thoracic survey. All studies underwent primary interpretation by one or two radiologists. The study radiologist independently reviewed all images from 13 patients with positive findings on radiography, CT or autopsy. Sensitivity and specificity between observers and imaging modalities were compared. Primary interpretation: Fractures were recognized on radiography in 5/12 patients who had fractures found at autopsy, and on CT in 8/12 patients. In total, 29% (24/83) of fractures were reported on radiography, and 51% (52/101) of fractures were reported on CT. Study radiologist: Fractures were recognized on radiography in 7/12 patients who had fractures found at autopsy, and on CT in 11/12 patients. In total, 46% (38/83) of fractures were reported on radiography, and 85% (86/101) of fractures were reported on CT. Postmortem thoracic CT provides greater sensitivity than radiography in detecting pediatric rib fractures, most notably in anterior and posterior fractures. However, the degree of improvement in sensitivity provided by CT might depend on observer experience.
    Pediatric Radiology 01/2011; 41(6):736-48. · 1.57 Impact Factor
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    ABSTRACT: PURPOSE Postmortem thoracic imaging is often obtained for assessment of the ribs. The purpose of this study was to determine the potential additional value of thoracic CT compared with radiography using forensic pathologic examination (FPE) as a gold standard. METHOD AND MATERIALS We retrospectively reviewed all coroner’s cases with both postmortem XR and CT skeletal survey acquired between January 2007 and October 2009. The study population included 1294 ribs from 55 patients (male = 35, female = 20, mean age = 1.0 years, patients less than 2 years = 45). In 11 patients (male = 8, female = 3, mean age = 1.7 years, patients less than 2 years = 7), 83 fractures were identified by FPE from among 250 ribs. All studies underwent initial review by two radiologists with the exception of 2 XR and 3 CT studies. The study radiologist reinterpreted all XR and CT images from the subset with positive findings, and determined the number, location, and presence or absence of healing for each fracture. Sensitivity and specificity was calculated for the reporting and study radiologists and compared using the Generalized Estimation Equation. 3D CT volume reconstructions were created and reviewed by the study radiologist following image reinterpretation. RESULTS CT improved overall sensitivity of the reporting and study radiologists by 17% and 38% respectively. For the reporting radiologists, differences in sensitivity between XR and CT did not reach significance. For the study radiologist, sensitivity of CT overall (p = 0.0122) and in anterior fractures (p = 0.0034) was significantly greater than XR. In addition, sensitivity of CT in fractures both with and without healing was significantly greater than XR (p < 0.05). Specificity for all readers was greater than 99% in both XR and CT. CONCLUSION Postmortem CT may detect significantly more pediatric rib fractures than XR, the majority of which may be anterior fractures. Radiologic-pathologic correlation suggests that overall sensitivity of post-mortem CT may be as high as 84% and that CT may identify fractures missed by autopsy. However, fractures will still be found at autopsy not seen by imaging. 3D CT volume reconstructions may be aid detection of subtle fractures missed by XR. CLINICAL RELEVANCE/APPLICATION Increased sensitivity afforded by thoracic CT may be of particular importance in abuse cases where the detection of fractures may have medicolegal implications.
    Radiological Society of North America 2010 Scientific Assembly and Annual Meeting; 12/2010
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    ABSTRACT: Positron emission tomography (PET) using [F-18]2-fluoro-2-deoxyglucose (FDG) fused with CT ((18)F-FDG PET/CT) has been widely adopted in oncological imaging. However, it is known that benign lesions and other metabolically active tissues, such as brown adipose tissue (BAT), can accumulate (18)F-FDG, potentially resulting in false-positive interpretation. Previous studies have reported that (18)F-FDG uptake in BAT is more common in children than in adults. We illustrate BAT FDG uptake in various anatomical locations in children and adolescents. We also review what is known about the effects of patient-related physical attributes and environmental temperatures on BAT FDG uptake, and discuss methods used to reduce BAT FDG uptake on (18)F-FDG PET.
    Pediatric Radiology 12/2010; 41(6):759-68. · 1.57 Impact Factor
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    ABSTRACT: Osteonecrosis may result from complications in a variety of pediatric diseases and, in the early stages of healing, may be characterized by inflammation and hyperemia. While traditionally assessed by bone scintigraphy, osteonecrosis may also present upon [F-18]2-fluoro-2-deoxyglucose PET/CT. Differentiation of osteonecrosis from metastatic lesions is important to ensure accurate disease staging and to avoid unnecessary imaging and biopsy. Osteonecrosis typically presents at the interface of weight-bearing joints after prolonged chemotherapy with corticosteroid administration, although prevalence is greater in adults than in children. We describe a case of unilateral osteonecrosis in the tibia of an adolescent lymphoma patient, which first presented on FDG-PET/CT imaging after 2 months of combination chemotherapy with corticosteroid administration. This report should aid in recognizing rapid-onset osteonecrosis with atypical sites of involvement in pediatric patients.
    Pediatric Radiology 12/2010; 40 Suppl 1:S27-9. · 1.57 Impact Factor
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    ABSTRACT: PURPOSE Adult literature reports that prevalence of 18F-fluorodeoxyglucose (FDG) uptake in brown adipose tissue (BAT) is inversely correlated with outdoor temperature and suggests that prevalence may be relatively greater in females and in children. The purpose of this study was to investigate prevalence and anatomic distribution of FDG uptake in BAT of children in relation to outdoor temperature and body surface area (BSA). METHOD AND MATERIALS We retrospectively reviewed all whole-body FDG PET/CT scans in oncology patients from Feb 2007 through Feb 2009: 341 scans in 157 patients (M=87, F=70, mean age = 12 y, age range = 1 to 18 y). All scans were independently reviewed by an experienced nuclear medicine physician blinded to information from previous reporting and date of each examination. FDG uptake was assessed in the following anatomic regions associated with BAT deposition in children: cervical, supraclavicular and axillar, costovertebral and intercostal, upper mediastinal, internal mammary and pericardial, periaortic and periazygous, perirenal, and anterior abdominal wall. Degree of FDG uptake in each region was graded visually on a 3-point scale based on uptake intensity relative to liver: 1 – less than liver, 2 – equal to liver, 3 – greater than liver. Spearman rank correlation was used to analyze relationships between variables. RESULTS 105/341 (31%) scans contained at least one region with BAT-FDG uptake: 90/230 (39%) scans in patients over 10 y, and 15/111 (14%) scans in patients under 10 y. In females, there was an inverse relationship between the number of anatomic regions with BAT-FDG uptake and outdoor temperature (rs = -0.15025, p = 0.0207). Furthermore, in females, there was a positive relationship between BAT-FDG uptake and BSA independent of outdoor temperature (rs = 0.24827, p = 0.0001). No such relationships were observed in males. CONCLUSION BAT-FDG uptake is more prevalent among children than adults, especially in patients over 10 y. However, an inverse correlation with outdoor temperature was only observed in females. A positive correlation between BAT-FDG uptake and BSA was observed in females independent of changes in outdoor temperature. CLINICAL RELEVANCE/APPLICATION Cold temperatures, high BSA, and female sex may increase BAT-FDG uptake in children, thereby potentially increasing false positives in FDG-PET/CT scans of oncology patients.
    Radiological Society of North America 2010 Scientific Assembly and Annual Meeting; 11/2010
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    ABSTRACT: PURPOSE The study was conducted to determine whether the location of the Radiologic Transition Zone (RTZ) in patients with Hirschprung’s Disease (HD) correlates with age. We hypothesized that the RTZ is located more proximally relative to patient size in younger patients and lies relatively more distal with increasing age. We hypothesized that this is the result of a difference in the rate of growth of the aganglionic and ganglionic portions of the bowel. METHOD AND MATERIALS Forty-five pre-operative contrast enemas of patients with known HD who underwent surgical correction at the Toronto Hospital for Sick Children during a ten year period were retrospectively reviewed. Patients with no RTZ on the contrast enema exam were excluded. The distance of the RTZ from the anus (DFA) was measured with respect to the height of the L5 vertebral body (L5L) of each patient. The DFA/L5L ratio was then correlated with patient age in days. RESULTS The study included 45 patients between the ages of 1 and 365 days. The distance of the RTZ from the anus ranged from 105 to 1235 mm. The DFA/L5L ranged from 1.51 to 28.12. Male and female patients did not differ significantly in age, DFA, L5L, or DFA/L5L. Spearman's rank correlations suggest that there is a strong trend in which DFA (r=-0.215, p=0.176) and DFA/L5L (r=-0.234, p=0.141) are negatively associated with patient age. CONCLUSION The relatively small sample size (n=45) limits the study, however the trend towards negative associations of DFA (r=-0.215, p=0.176) and DFA/L5L (r=-0.234, p=0.141) are of interest. This carries great importance for surgical management since HD with a more distal transition zone is more amenable to newer single-stage laparoscopic and trans-anal surgical techniques. Future studies conducted with a larger sample size may reveal significant findings for these parameters. If so, these results would support postponing surgery for young patients with HD. CLINICAL RELEVANCE/APPLICATION These results may support postponing surgery for young patients with HD since a more distal transition zone is more amenable to newer single-stage laparoscopic and trans-anal surgical techniques.
    Radiological Society of North America 2009 Scientific Assembly and Annual Meeting; 12/2009