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Abstract
Abstract
An interlaboratory survey of the determination of trace elements in bovine liver was undertaken. Thirty-three laboratories from Australia and 15 from New Zealand returned results. Moisture determination results were variable despite the use of a recommended drying procedure. For the 10 trace elements determined, the mean values (μg/g) with their interlaboratory coefficients of variation (CV) were: cadmium, 1.2 (42.5%); cobalt, 0.21 (9.5%); copper, 110 (6.0%); iron, 276 (11.0%); lead, 0.6 (48.9%); manganese, 8.6 (13.9%); mercury, 0.03 (30.0%); molybdenum, 2.5 (45.6%); selenium, 1.0 (17.5%); zinc, 219 (8.2%). The intralaboratory CV for determining each of these elements was less than 9% except for the lead CV which was 20.2%. Results for the determination of sodium, potassium, calcium, and magnesium were also reported. The survey shows that while the use of a standard reference material can improve the performance of laboratories in trace element analysis, it may also introduce analytical bias.
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Affiliation(s)
- T S Koh
- Institute of Medical and Veterinary Science, Box 14, Rundle St PO, Adelaide, South Australia, Australia
| | - T H Benson
- Institute of Medical and Veterinary Science, Box 14, Rundle St PO, Adelaide, South Australia, Australia
| | - G J Judson
- Institute of Medical and Veterinary Science, Box 14, Rundle St PO, Adelaide, South Australia, Australia
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Li ZF, Zhao W, Qi TF, Gao C, Gu Q, Zhao JS, Koh TS. A simple B 1 correction method for dynamic contrast-enhanced MRI. ACTA ACUST UNITED AC 2018; 63:16NT01. [DOI: 10.1088/1361-6560/aad519] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Tai WM, Yong WP, Lim C, Low LS, Tham CK, Koh TS, Ng QS, Wang WW, Wang LZ, Hartono S, Thng CH, Huynh H, Lim KT, Toh HC, Goh BC, Choo SP. A phase Ib study of selumetinib (AZD6244, ARRY-142886) in combination with sorafenib in advanced hepatocellular carcinoma (HCC). Ann Oncol 2018; 29:526. [PMID: 28368515 DOI: 10.1093/annonc/mdx060] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
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4
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Abstract
The transfer constant K trans is commonly employed in dynamic contrast-enhanced MRI studies, but the utility and interpretation of K trans as a potential biomarker of tumor vasculature remains unclear. In this study, computer simulations based on a comprehensive tracer kinetic model with multiple pathways was used to provide clarification on the interpretation and application of K trans. Tissue concentration-time curves pertaining to a wide range of transport conditions were simulated using the multiple-pathway (MP) model and fitted using the generalized kinetic (GK) and extended GK models. Relationships between K trans and plasma flow F p, vessel permeability PS and extraction rate EF p under various transport conditions were assessed by correlation and regression analysis. Results show that the MP model provides an alternative two-tier interpretation of K trans based on the vascular transit time. K trans is primarily associated with F p and EF p respectively, in the slow and rapid vascular transit states, independent of the magnitude of PS. The relative magnitudes of PS and F p only serve as secondary constraints for which K trans can be further associated with EF p and PS in the slow and rapid transit states, respectively.
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Affiliation(s)
- T S Koh
- Department of Oncologic Imaging, National Cancer Center, 169610, Singapore. Duke-NUS Graduate Medical School, 169857, Singapore
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Yan YY, Hartono S, Hennedige T, Koh TS, Chan CM, Zhou L, Rumpel H, Martarello L, Khoo JB, Koh DM, Chuang KH, Tony Lim KH, Dan YY, Thng CH. Intravoxel incoherent motion and diffusion tensor imaging of early renal fibrosis induced in a murine model of streptozotocin induced diabetes. Magn Reson Imaging 2017; 38:71-76. [PMID: 28038964 DOI: 10.1016/j.mri.2016.12.023] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 12/24/2016] [Accepted: 12/25/2016] [Indexed: 12/21/2022]
Abstract
INTRODUCTION To assess if parameters in intravoxel incoherent motion (IVIM) and diffusion tensor imaging (DTI) can be used to evaluate early renal fibrosis in a mouse model of diabetic nephropathy. MATERIALS & METHODS In a population of 38 male CD1 mice (8weeks old, 20-30g), streptozotocin induced diabetes was created in 20 mice via a single intraperitoneal injection of streptozotocin at 150mg/kg, while 18 mice served as control group. IVIM parameters were acquired at 0, 12 and 24weeks after injection of streptozotocin using a range of b values from 0 to 1200s/mm2. DTI parameters were obtained using 12 diffusion directions and lower b values of 0, 100 and 400s/mm2. DTI and IVIM parameters were obtained using region of interests drawn over the renal parenchyma. Histopathological analysis of the right kidney was performed in all mice. Results were analyzed using an unpaired t-test with P<0.05 considered statistically significant. RESULTS Renal cortex fractional anisotropy (FA) was significantly lower in the diabetes group at week 12 as compared with the control group. Renal cortex apparent diffusion coefficient and tissue diffusivity were significantly higher in the diabetes group at week 12 compared with the control group at 12weeks. Blood flow was significantly decreased at the renal medulla at 24weeks. Histopathological analysis confirmed fibrosis in the diabetes group at 24weeks. CONCLUSION FA is significantly reduced in diabetic nephropathy. FA might serve a potential role in the detection and therapy monitoring of early diabetic nephropathy.
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Affiliation(s)
- Y Y Yan
- Department of Oncologic Imaging, National Cancer Centre, Singapore.
| | - S Hartono
- Department of Oncologic Imaging, National Cancer Centre, Singapore
| | - T Hennedige
- Department of Oncologic Imaging, National Cancer Centre, Singapore
| | - T S Koh
- Department of Oncologic Imaging, National Cancer Centre, Singapore
| | - C M Chan
- Department of Renal Medicine, General Hospital, Singapore, Singapore
| | - L Zhou
- Division of Gastroenterology & Hepatology, National University Hospital, Singapore
| | - H Rumpel
- Department of Diagnostic Radiology, Singapore General Hospital, Singapore
| | - L Martarello
- Roche-Singapore Hub for Translational Medicine, Singapore
| | - J B Khoo
- Department of Oncologic Imaging, National Cancer Centre, Singapore
| | - D M Koh
- Royal Marsden Hospital, Surrey, UK
| | - K H Chuang
- Singapore Bioimaging Consortium, Singapore
| | - K H Tony Lim
- Department of Pathology, Singapore General Hospital, Singapore
| | - Y Y Dan
- Division of Gastroenterology & Hepatology, National University Hospital, Singapore
| | - C H Thng
- Department of Oncologic Imaging, National Cancer Centre, Singapore
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Tai WM, Yong WP, Lim C, Low LS, Tham CK, Koh TS, Ng QS, Wang WW, Wang LZ, Hartano S, Thng CH, Huynh H, Lim KT, Toh HC, Goh BC, Choo SP. A phase Ib study of selumetinib (AZD6244, ARRY-142886) in combination with sorafenib in advanced hepatocellular carcinoma (HCC). Ann Oncol 2016; 27:2210-2215. [PMID: 27681866 DOI: 10.1093/annonc/mdw415] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 08/22/2016] [Accepted: 08/22/2016] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Treatment with sorafenib, although associated with inhibition of tumour growth and angiogenesis in in vivo studies, leads to up-regulation of pERK. The addition of MEK inhibition could potentially abrogate this effect and potentiate anti-tumour activity. This phase I study investigated the maximum tolerated dose (MTD), safety, tolerability, pharmacokinetics (PK) and biomarker correlates of selumetinib combined with sorafenib in patients with advanced hepatocellular carcinoma (HCC). METHODS Patients with Child-Pugh (CP) score ≤7 were treated with 400 mg twice daily of sorafenib with escalating doses of selumetinib in a 3 + 3 study design. The dose-limiting toxicity (DLT) evaluation period was 28 days. PK of selumetinib was determined. Angiogenic effect was evaluated with dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). RESULTS Twenty-seven patients of Asian ethnicity were enrolled. The MTD was selumetinib 75 mg daily with sorafenib 400 mg twice daily. DLT included grade 3 transaminitis, diarrhoea and fatigue. Most common treatment-related adverse events at MTD (all grades) were diarrhoea (85%), rash (59%), hypertension (44%), fatigue (30%), anorexia (22%) and hand-foot syndrome (22%). Four patients (15%) had PR and 13 (48%) had SD. PR or SD was observed for ≥6 months in seven patients. The median overall survival was 14.4 months. Selumetinib exposures in combination with sorafenib were comparable to other monotherapy studies. A reduction in permeability-surface area product noted in DCE-MRI with treatment correlated with worse survival outcomes. CONCLUSION The MTD of selumetinib was 75 mg daily when combined with sorafenib 400 mg twice a day in CP ≤7 HCC. Acceptable adverse events and encouraging anti-tumour activity warrant further evaluation. DCE-MRI findings deserve prospective evaluation. CLINICALTRIALSGOV IDENTIFIER NCT01029418.
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Affiliation(s)
- W M Tai
- Department of Medical Oncology, National Cancer Centre Singapore, Singapore
| | - W P Yong
- Department of Haematology-Oncology, National University Health System, Singapore
| | - C Lim
- Divisions of Clinical Trials and Epidemiological Sciences
| | - L S Low
- Divisions of Clinical Trials and Epidemiological Sciences
| | - C K Tham
- Department of Medical Oncology, National Cancer Centre Singapore, Singapore
| | - T S Koh
- Oncologic Imaging, National Cancer Centre Singapore, Singapore
| | - Q S Ng
- Department of Medical Oncology, National Cancer Centre Singapore, Singapore
| | - W W Wang
- Department of Medical Oncology, National Cancer Centre Singapore, Singapore
| | - L Z Wang
- Cancer Science Institute of Singapore, National University of Singapore, Singapore
| | - S Hartano
- SingHealth Duke-NUS Radiological Sciences Academic Clinical Program, Singapore
| | - C H Thng
- Oncologic Imaging, National Cancer Centre Singapore, Singapore
| | - H Huynh
- Laboratory of Molecular Endocrinology, Division of Molecular and Cellular Research, National Cancer Centre Singapore, Singapore
| | - K T Lim
- Department of Pathology, Singapore General Hospital, Singapore, Singapore
| | - H C Toh
- Department of Medical Oncology, National Cancer Centre Singapore, Singapore
| | - B C Goh
- Department of Haematology-Oncology, National University Health System, Singapore
| | - S P Choo
- Department of Medical Oncology, National Cancer Centre Singapore, Singapore
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Teo QQ, Thng CH, Koh TS, Ng QS. Dynamic contrast-enhanced magnetic resonance imaging: applications in oncology. Clin Oncol (R Coll Radiol) 2014; 26:e9-20. [PMID: 24931594 DOI: 10.1016/j.clon.2014.05.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Revised: 04/22/2014] [Accepted: 04/28/2014] [Indexed: 12/29/2022]
Abstract
Dynamic contrast-enhanced magnetic resonance imaging (DCE MRI) allows functional characterisation of tissue perfusion characteristics and acts as a biomarker for tumour angiogenesis. It involves serial acquisition of MRI images before and after injection of contrast, as such, tissue perfusion and permeability can be assessed based on the signal enhancement kinetics. The ability to evaluate whole tumour volumes in a non-invasive manner makes DCE MRI especially attractive for potential oncological applications. Here we provide an overview of the current research involving DCE MRI as a biomarker for the diagnosis and characterisation of malignancies, prediction of the therapeutic response and survival outcomes, as well as radiation therapy planning.
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Affiliation(s)
- Q Q Teo
- Duke NUS Graduate Medical School Singapore, Singapore
| | - C H Thng
- Department of Oncologic Imaging, National Cancer Centre Singapore, Singapore
| | - T S Koh
- Department of Oncologic Imaging, National Cancer Centre Singapore, Singapore
| | - Q S Ng
- Department of Medical Oncology, National Cancer Centre Singapore, Singapore.
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Koh TS, Shi W, Thng CH, Ho JTS, Khoo JBK, Cheong DLH, Lim TCC. Assessment of tumor blood flow distribution by dynamic contrast-enhanced CT. IEEE Trans Med Imaging 2013; 32:1504-1514. [PMID: 23625351 DOI: 10.1109/tmi.2013.2258404] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
A distinct feature of the tumor vasculature is its tortuosity and irregular branching of vessels, which can translate to a wider dispersion and higher variability of blood flow in the tumor. To enable tumor blood flow variability to be assessed in vivo by imaging, a tracer kinetic model that accounts for flow dispersion is developed for use with dynamic contrast-enhanced (DCE) CT. The proposed model adopts a multiple-pathway approach and allows for the quantification of relative dispersion in the blood flow distribution, which reflects flow variability in the tumor vasculature. Monte Carlo simulation experiments were performed to study the possibility of reducing the number of model parameters based on the Akaike information criterion approach and to explore possible noise and tissue conditions in which the model might be applicable. The model was used for region-of-interest analysis and to generate perfusion parameter maps for three patient DCE CT cases with cerebral tumors, to illustrate clinical applicability.
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Affiliation(s)
- T S Koh
- Department of Oncologic Imaging, National Cancer Center, 169610 Singapore
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Koh TS, Shi W, Thng CH, Kwek JW, Bisdas S, Khoo JBK. Corrigendum: Interpretation and applicability of empirical tissue enhancement metrics in dynamic contrast-enhanced MRI based on a multiple pathway model. Phys Med Biol 2013. [DOI: 10.1088/0031-9155/58/6/2009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Choo SP, Chowbay B, Ng QS, Thng CH, Lim C, Hartono S, Koh TS, Huynh H, Poon D, Ang MK, Chang S, Toh HC. A Phase 1 dose-finding and pharmacodynamic study of rapamycin in combination with bevacizumab in patients with unresectable hepatocellular carcinoma. Eur J Cancer 2012; 49:999-1008. [PMID: 23265712 DOI: 10.1016/j.ejca.2012.11.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Revised: 11/06/2012] [Accepted: 11/06/2012] [Indexed: 11/17/2022]
Abstract
BACKGROUND & AIMS Preclinical studies have demonstrated the additive effect of rapamycin with bevacizumab for hepatocellular carcinoma treatment. We conducted a Phase 1 study to evaluate the safety and pharmacokinetics of the combination in patients with hepatocellular carcinoma. METHODS Adult participants with advanced hepatocellular carcinoma received intravenous bevacizumab (5mg/kg every 14 days) and oral rapamycin (1-6 mg/day; 3+3 dose escalation design). Computed tomography assessed tumour response and treatment safety. Pharmacokinetics assessment established rapamycin blood concentrations pre- and post-dose. Dynamic contrast-enhanced computed tomography analysed the tumour region for blood flow, permeability surface area product, fractional intravascular blood volume and extracellular-extravascular volume. RESULTS Twenty-four participants were treated. There were two dose limiting toxicities with rapamycin 5mg: grade 3 thrombocytopenia and grade 3 mucositis. The maximally tolerated dose of rapamycin was 4 mg. Adverse events (grade 1-2) included hyperglycaemia (83%), thrombocytopenia (75%), fatigue (46%), mucositis (46%), anorexia (42%), diarrhoea (33%) and proteinuria (12.5%). Of 20 evaluable participants, one reached complete response that lasted 4.5 months, two reached partial response, 14 reached stable disease and three had progressive disease. Median overall survival was 9.4 months; progression-free survival was 5.5 months. Dose level and steady state area under the concentration time curve for hour zero to infinity of rapamycin correlated inversely with blood flow rate and change in permeability-surface area. After 22 days of treatment, there were significant reductions from baseline in blood flow rate, permeability-surface area and fractional intracellular blood volume. CONCLUSIONS The recommended Phase 2 dose of rapamycin is 4 mg in combination with bevacizumab. Evidence of anti-vascular activity was observed together with promising clinical activity.
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MESH Headings
- Adult
- Aged
- Aged, 80 and over
- Antibodies, Monoclonal, Humanized/administration & dosage
- Antibodies, Monoclonal, Humanized/adverse effects
- Antibodies, Monoclonal, Humanized/pharmacokinetics
- Antineoplastic Combined Chemotherapy Protocols/administration & dosage
- Antineoplastic Combined Chemotherapy Protocols/adverse effects
- Antineoplastic Combined Chemotherapy Protocols/pharmacokinetics
- Bevacizumab
- Carcinoma, Hepatocellular/drug therapy
- Carcinoma, Hepatocellular/metabolism
- Carcinoma, Hepatocellular/pathology
- Dose-Response Relationship, Drug
- Female
- Hepatectomy
- Humans
- Liver Neoplasms/drug therapy
- Liver Neoplasms/metabolism
- Liver Neoplasms/pathology
- Male
- Maximum Tolerated Dose
- Middle Aged
- Sirolimus/administration & dosage
- Sirolimus/adverse effects
- Sirolimus/pharmacokinetics
- Treatment Outcome
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Affiliation(s)
- S P Choo
- Medical Oncology, National Cancer Centre Singapore, Singapore.
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Koh TS, Shi W, Thng CH, Kwek JW, Bisdas S, Khoo JBK. Interpretation and applicability of empirical tissue enhancement metrics in dynamic contrast-enhanced MRI based on a multiple pathway model. Phys Med Biol 2012; 57:N279-94. [DOI: 10.1088/0031-9155/57/15/n279] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Hartono S, Thng CH, Ng QS, Yong CX, Yang CT, Shi W, Chuang KH, Koh TS. High temporal resolution dynamic contrast-enhanced MRI at 7 Tesla: a feasibility study with mouse liver model. Annu Int Conf IEEE Eng Med Biol Soc 2012; 2011:2788-91. [PMID: 22254920 DOI: 10.1109/iembs.2011.6090763] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) has been widely applied to evaluate microcirculatory parameters in clinical settings. However, pre-clinical studies involving DCE-MRI of small animals remain challenging with the requirement for high spatial and temporal resolution for quantitative tracer kinetic analysis. This study illustrates the feasibility of applying a high temporal resolution (2 s) protocol for liver imaging in mice by analyzing the DCE-MRI datasets of mice liver with a dual-input two-compartment tracer kinetic model. Phantom studies were performed to validate the T(1) estimates derived by the proposed protocol before applying it in mice studies. The DCE-MRI datasets of mice liver were amendable to tracer kinetic analysis using a dual-input two-compartment model. Estimated micro-circulatory parameters were consistent with liver physiology, indicating viability of applying the technique for pre-clinical drug developments.
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Affiliation(s)
- S Hartono
- National Cancer Centre Singapore and Nanyang Technological University, Singapore
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Koh TS, Hartono S, Thng CH, Lim TKH, Martarello L, Ng QS. In vivo measurement of gadolinium diffusivity by dynamic contrast-enhanced MRI: A preclinical study of human xenografts. Magn Reson Med 2012; 69:269-76. [DOI: 10.1002/mrm.24246] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Revised: 02/15/2012] [Accepted: 02/17/2012] [Indexed: 12/22/2022]
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Koh TS, Thng CH, Hartono S, Kwek JW, Khoo JBK, Miyazaki K, Collins DJ, Orton MR, Leach MO, Lewington V, Koh DM. Dynamic contrast-enhanced MRI of neuroendocrine hepatic metastases: A feasibility study using a dual-input two-compartment model. Magn Reson Med 2011; 65:250-60. [PMID: 20860001 DOI: 10.1002/mrm.22596] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Neuroendocrine hepatic metastases exhibit various contrast uptake enhancement patterns in dynamic contrast-enhanced MRI. Using a dual-input two-compartment distributed parameter model, we analyzed the dynamic contrast-enhanced MRI datasets of seven patient study cases with the aim to relate the tumor contrast uptake patterns to parameters of tumor microvasculature. Simulation studies were also performed to provide further insights into the effects of individual microcirculatory parameter on the tumor concentration-time curves. Although the tumor contrast uptake patterns can be influenced by many parameters, initial results indicate that hepatic blood flow and the ratio of fractional vascular volume to fractional interstitial volume may potentially distinguish between the patterns of neuroendocrine hepatic metastases.
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Affiliation(s)
- T S Koh
- Department of Oncologic Imaging, National Cancer Center, Singapore.
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15
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Koh TS, Cheong DLH, Hou Z. Issues of discontinuity in the impulse residue function for deconvolution analysis of dynamic contrast-enhanced MRI data. Magn Reson Med 2011; 66:886-92. [DOI: 10.1002/mrm.22868] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2010] [Revised: 01/11/2011] [Accepted: 01/17/2011] [Indexed: 11/11/2022]
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Surlan-Popovic K, Bisdas S, Rumboldt Z, Koh TS, Strojan P. Changes in perfusion CT of advanced squamous cell carcinoma of the head and neck treated during the course of concomitant chemoradiotherapy. AJNR Am J Neuroradiol 2010; 31:570-5. [PMID: 19875475 DOI: 10.3174/ajnr.a1859] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
BACKGROUND AND PURPOSE Concomitant chemoradiation is a promising therapy for the treatment of locoregionally advanced head and neck carcinoma. The purpose of this study was to prospectively evaluate early changes in primary tumor perfusion parameters during concomitant cisplatin-based chemoradiotherapy of locoregionally advanced SCCHN and to evaluate their predictive value for response of the primary tumor to therapy. MATERIALS AND METHODS Twenty patients with locoregionally advanced SCCHN underwent perfusion CT scans before therapy and after completion of 40 Gy and 70 Gy of chemoradiotherapy. BF, BV, MTT, and PS of primary tumors were quantified. Differences in perfusion and tumor volume values during the therapy as well as between responders and nonresponders were analyzed, and ROC curves were used to assess predictive value of the baseline and follow-up functional parameters. RESULTS The tumor volumes at 40 Gy and at 70 Gy were significantly lower compared with baseline values (P = .014 and P = .007). In the 6 nonresponders, measurements after 40 Gy showed a nonsignificant trend of increased BF, BV, and PS values compared with the baseline values (P = .06). In 14 responders, a significant reduction of BF values was recorded after 40 Gy (P = .04) and after 70 Gy (P = .01). In responders, BV values showed a reduction after 40 Gy followed by a plateau after 70 Gy (P = .04), whereas in nonresponders there was a nonsignificant elevation of the BV. Baseline BV predicted short-term tumor response with a sensitivity of 60% and specificity of 100% (P = .01). After completion of 40 Gy of concomitant chemoradiation BV was a more significant predictor than were BF and MTT. CONCLUSIONS The results suggest that in advanced SCCHN the perfusion CT monitoring might be of predictive value for identifying tumors that may respond to cisplatin-based chemoradiotherapy.
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Affiliation(s)
- K Surlan-Popovic
- Department of Radiology, University Clinical Centre, Ljubljana, Slovenia
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Bisdas S, Rumboldt Z, Surlan-Popovic K, Baghi M, Koh TS, Vogl TJ, Mack MG. Perfusion CT in squamous cell carcinoma of the upper aerodigestive tract: long-term predictive value of baseline perfusion CT measurements. AJNR Am J Neuroradiol 2009; 31:576-81. [PMID: 19875471 DOI: 10.3174/ajnr.a1852] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE PCT studies hold short-term predictive value in patients treated with chemoradiotherapy. Our aim was to examine the long-term predictive value of baseline PCT studies for local tumor control and overall survival in SCCA of the upper aerodigestive tract treated with chemoradiotherapy. MATERIALS AND METHODS Eighty-four patients with advanced SCCA underwent PCT followed by concomitant chemoradiation. The acquired perfusion maps represented BF, BV, MTT, and PS. Visual analysis of the parametric maps for identification of tumor perfusion patterns was conducted. ROC curves, t tests, and Kaplan-Meier survival curves were plotted for local disease control and overall survival. RESULTS The median time of local tumor control was 24 months. The BF and PS values were significantly higher in patients who had no recurrence than in those with local failure (P < or = .02). The BF and PS were predictive (P < or = .0006) but BV and MTT held no significant predictive values for local tumor control. The patients with high BF and PS had a longer local tumor control than the patients with hypoperfused tumors (P = .0007). A visually detected BF-BV mismatch had a sensitivity/specificity of 63%/66% (P = .03) and 59%/69% (P = .03) for local tumor control and OS, respectively. Patients without mismatch lived significantly longer than patients with mismatch (P = .01). CONCLUSIONS BF, PS, and mismatch of BF-BV are significant predictors of local tumor control after chemoradiation in SCCA of the upper aerodigestive tract.
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Affiliation(s)
- S Bisdas
- Department of Neuroradiology, Eberhard Karls University, Tübingen, Germany.
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18
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Bisdas S, Rumboldt Z, Wagenblast J, Baghi M, Koh TS, Hambek M, Vogl TJ, Mack MG. Response and progression-free survival in oropharynx squamous cell carcinoma assessed by pretreatment perfusion CT: comparison with tumor volume measurements. AJNR Am J Neuroradiol 2009; 30:793-9. [PMID: 19351906 PMCID: PMC7051758 DOI: 10.3174/ajnr.a1449] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2008] [Accepted: 11/10/2008] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Perfusion CT (PCT) provides a rapid, reliable, and non-invasive technique for assessing tumor vascularity. The purpose of this study was to assess whether pretreatment dynamic perfusion CT (PCT) may predict response to induction chemotherapy and midterm progression-free survival (PFS) in advanced oropharynx squamous cell carcinoma (SCCA) and to compare the results with those derived by tumor volume measurements. MATERIALS AND METHODS Nineteen patients underwent routine contrast-enhanced CT (CECT), pretreatment PCT, and conventional endoscopy. Tumor response was determined according to radiologic (RECIST) criteria. The PCT parameters, tumor volume, radiologic response, and PFS were analyzed with use of Cox-proportional hazards model, receiver operating characteristic (ROC), and Kaplan-Meier analysis. RESULTS The baseline blood flow (BF), blood volume (BV), and permeability surface area product (PS) were significantly higher, whereas mean transit time (MTT) was significantly lower in the responders than in the nonresponders (P < or = .002). BV showed 100% sensitivity, MTT and PS had the highest specificity (100%), and BF showed 84.2% sensitivity and 66.7% specificity for prediction of tumor response after induction chemotherapy. The pretreatment tumor volume correlated with PFS in the pooled patients group (r = 0.4; P < .0001), whereas postinduction tumor volume correlated significantly with PFS in the responders and nonresponders (r = 0.22-0.64; P < or = .006). Pretreatment tumor volume (P = .0001) and BF (P = .001) were significant predictors for PFS. CONCLUSIONS Pretreatment PCT parameters may predict response after induction chemotherapy. Tumor volume and BF values may predict PFS in patients with advanced oropharyngeal SCCA.
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Affiliation(s)
- S Bisdas
- Department of Radiology, Johann Wolfgang Goethe University, Frankfurt, Germany.
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Soo RA, McKeegan E, Chen CS, Thng CH, Koh TS, Laird D, Zhang K, Wong CI, Gupta N, Goh BC. The effect of varying doses of ABT-869 on biomarkers of angiogenesis and their correlation with pharmacodynamic outcome. J Clin Oncol 2008. [DOI: 10.1200/jco.2008.26.15_suppl.14535] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Thng CH, Hartono S, Koh TS, Rumpel H, Ong AB, Sukri N, Tai BC, Soo RA, Humerickhouse R, Goh BC. Dynamic contrast enhanced MRI (DCE MRI) for Phase I anti-angiogenic trial: Comparison of the transfer constant (Ktrans) to blood flow and permeability derived by a distributed parameter model. J Clin Oncol 2008. [DOI: 10.1200/jco.2008.26.15_suppl.3514] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Koh TS. On the a Priori Identifiability of the Two-Compartment Distributed Parameter Model From Residual Tracer Data Acquired by Dynamic Contrast-Enhanced Imaging. IEEE Trans Biomed Eng 2008; 55:340-4. [DOI: 10.1109/tbme.2007.910682] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Bisdas S, Baghi M, Wagenblast J, Knecht R, Thng CH, Koh TS, Vogl TJ. Differentiation of benign and malignant parotid tumors using deconvolution-based perfusion CT imaging: Feasibility of the method and initial results. Eur J Radiol 2007; 64:258-65. [PMID: 17399933 DOI: 10.1016/j.ejrad.2007.02.032] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2006] [Revised: 02/18/2007] [Accepted: 02/23/2007] [Indexed: 10/23/2022]
Abstract
AIM We evaluated the feasibility of perfusion CT (CTP) of the parotid gland and attempted to differentiate benign from malignant tumors. MATERIALS AND METHODS CTP was performed in 17 patients with benign tumors and 10 patients with malignant parotid tumors. Data were postprocessed by using deconvolution-based perfusion analysis. Postprocessing-generated maps showed blood flow (BF), blood volume (BV), mean transit time (MTT), and capillary permeability surface product (PS). Regions of interest were placed through the tumor site and the contralateral healthy parotid tissue. Ratios of the perfusion values between the tumors and the contralateral healthy structures were also calculated. Pearson correlation coefficients were determined to compare the agreement between the two readers. RESULTS Perfusion maps of all tumors were successfully obtained. High Pearson correlation coefficients comparing the two readers' visually measured abnormalities were observed (r=0.79-0.86, P=0.001) for all perfusion maps, The MTT and PS values between malignant and benign tumors were not significantly different. The BF and BV values were statistically significant different between the benign and malignant tumors (0.00<P<0.02). Only the BV ratio criterion between malignant and benign neoplasms was statistically significant (P<0.004). CONCLUSIONS CTP of the parotid gland is feasible and may differentiate malignant from non-malignant lesions by means of absolute BF, BV and BV ratio values.
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Affiliation(s)
- S Bisdas
- Department of Diagnostic and Interventional Radiology, Johann Wolfgang Goethe University Hospital, Frankfurt, Germany.
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Bisdas S, Yang X, Lim CCT, Vogl TJ, Koh TS. Delineation and segmentation of cerebral tumors by mapping blood-brain barrier disruption with dynamic contrast-enhanced CT and tracer kinetics modeling-a feasibility study. Eur Radiol 2007; 18:143-51. [PMID: 17701183 DOI: 10.1007/s00330-007-0726-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2007] [Revised: 05/31/2007] [Accepted: 07/06/2007] [Indexed: 12/01/2022]
Abstract
Dynamic contrast-enhanced (DCE) imaging is a promising approach for in vivo assessment of tissue microcirculation. Twenty patients with clinical and routine computed tomography (CT) evidence of intracerebral neoplasm were examined with DCE-CT imaging. Using a distributed-parameter model for tracer kinetics modeling of DCE-CT data, voxel-level maps of cerebral blood flow (F), intravascular blood volume (vi) and intravascular mean transit time (t1) were generated. Permeability-surface area product (PS), extravascular extracellular blood volume (ve) and extraction ratio (E) maps were also calculated to reveal pathologic locations of tracer extravasation, which are indicative of disruptions in the blood-brain barrier (BBB). All maps were visually assessed for quality of tumor delineation and measurement of tumor extent by two radiologists. Kappa (kappa) coefficients and their 95% confidence intervals (CI) were calculated to determine the interobserver agreement for each DCE-CT map. There was a substantial agreement for the tumor delineation quality in the F, ve and t1 maps. The agreement for the quality of the tumor delineation was excellent for the vi, PS and E maps. Concerning the measurement of tumor extent, excellent and nearly excellent agreement was achieved only for E and PS maps, respectively. According to these results, we performed a segmentation of the cerebral tumors on the base of the E maps. The interobserver agreement for the tumor extent quantification based on manual segmentation of tumor in the E maps vs. the computer-assisted segmentation was excellent (kappa = 0.96, CI: 0.93-0.99). The interobserver agreement for the tumor extent quantification based on computer segmentation in the mean images and the E maps was substantial (kappa = 0.52, CI: 0.42-0.59). This study illustrates the diagnostic usefulness of parametric maps associated with BBB disruption on a physiology-based approach and highlights the feasibility for automatic segmentation of cerebral tumors.
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Affiliation(s)
- S Bisdas
- Department of Diagnostic and Interventional Radiology, Johann Wolfgang Goethe University Hospital, Theodor-Stern-Kai 7, D-60590 Frankfurt, Germany.
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Thng CH, Koh TS, Rumpel H, Khoo JB, Ong AB, Sukri N, Tai BC, Soo RA, Humerickhouse R, Goh BC. Dynamic contrast enhanced MRI (DCE MRI) for assessment of effects of anti-angiogenic therapy: Comparison of the transfer constant (Ktrans) to blood flow and permeability derived by a distributed parameters model. J Clin Oncol 2007. [DOI: 10.1200/jco.2007.25.18_suppl.14109] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
14109 Background: Transfer constant (Ktrans) and IAUC60 normalized with arterial input function are commonly used dynamic contrast enhanced magnetic resonance imaging (DCE MRI) parameters. The distributed parameters model (DP) is a DCE MRI model that enables derivation of blood flow and capillary permeability-surface area product (PS). We aim to study the distributed parameters model as an alternative method of angiogenesis assessment and correlate the above parameters to drug exposure and patient outcome in a Phase I anti- angiogenic trial. Methods: Fifteen evaluable patients from an on-going Phase I trial (ABT 869) with 3 dose escalations formed the study population. Pharmacokinetic study was performed on Day 1 and the area under the concentration time curve extrapolated to infinity (AUCinfinity) was used as an indicator of drug exposure. All patients underwent DCE MRI at baseline, Day 3 and Day 15 with temporal resolution of 4 seconds. Gadolinium concentrations were estimated using a dual flip angle method. Patients demonstrating progressive disease in first 2 evaluation scans (cycle 2 or 4) based on RECIST criteria were considered progressors and all other patients non-progressors. Receiver operating curve (ROC) analysis was performed. Correlation with AUCinfinity was analyzed. Results: There is good correlation (Spearman’s coefficient -0.67, p = 0.008) between AUCinfinity and DP derived PS and less strong correlation with normalized IAUC60 (Spearman’s coefficient -0.57, p = 0.03). There is no correlation for Ktrans (Spearman’s coefficient 0.04). ROC analysis for predicting progressors versus non-progressors showed a higher ROC area for PS compared to Ktrans (0.83 versus 0.47, p = 0.037). Normalized IAUC60 showed a slightly lower area compared to PS (0.77 versus 0.83) but the difference is not significant (p = 0.58). Conclusions: PS derived from DP model shows better correlation with drug exposure and may predict patient outcome better than Ktrans. [Table: see text]
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Affiliation(s)
- C. H. Thng
- National Cancer Centre, Singapore, Singapore, Singapore; Nanyang Technological University, Singapore, Singapore; Singapore General Hospital, Singapore, Singapore; National University Hospital, Singapore, Singapore; National University of Singapore, Singapore, Singapore; Abbott Laboratories, Abbott Park, IL
| | - T. S. Koh
- National Cancer Centre, Singapore, Singapore, Singapore; Nanyang Technological University, Singapore, Singapore; Singapore General Hospital, Singapore, Singapore; National University Hospital, Singapore, Singapore; National University of Singapore, Singapore, Singapore; Abbott Laboratories, Abbott Park, IL
| | - H. Rumpel
- National Cancer Centre, Singapore, Singapore, Singapore; Nanyang Technological University, Singapore, Singapore; Singapore General Hospital, Singapore, Singapore; National University Hospital, Singapore, Singapore; National University of Singapore, Singapore, Singapore; Abbott Laboratories, Abbott Park, IL
| | - J. B. Khoo
- National Cancer Centre, Singapore, Singapore, Singapore; Nanyang Technological University, Singapore, Singapore; Singapore General Hospital, Singapore, Singapore; National University Hospital, Singapore, Singapore; National University of Singapore, Singapore, Singapore; Abbott Laboratories, Abbott Park, IL
| | - A. B. Ong
- National Cancer Centre, Singapore, Singapore, Singapore; Nanyang Technological University, Singapore, Singapore; Singapore General Hospital, Singapore, Singapore; National University Hospital, Singapore, Singapore; National University of Singapore, Singapore, Singapore; Abbott Laboratories, Abbott Park, IL
| | - N. Sukri
- National Cancer Centre, Singapore, Singapore, Singapore; Nanyang Technological University, Singapore, Singapore; Singapore General Hospital, Singapore, Singapore; National University Hospital, Singapore, Singapore; National University of Singapore, Singapore, Singapore; Abbott Laboratories, Abbott Park, IL
| | - B. C. Tai
- National Cancer Centre, Singapore, Singapore, Singapore; Nanyang Technological University, Singapore, Singapore; Singapore General Hospital, Singapore, Singapore; National University Hospital, Singapore, Singapore; National University of Singapore, Singapore, Singapore; Abbott Laboratories, Abbott Park, IL
| | - R. A. Soo
- National Cancer Centre, Singapore, Singapore, Singapore; Nanyang Technological University, Singapore, Singapore; Singapore General Hospital, Singapore, Singapore; National University Hospital, Singapore, Singapore; National University of Singapore, Singapore, Singapore; Abbott Laboratories, Abbott Park, IL
| | - R. Humerickhouse
- National Cancer Centre, Singapore, Singapore, Singapore; Nanyang Technological University, Singapore, Singapore; Singapore General Hospital, Singapore, Singapore; National University Hospital, Singapore, Singapore; National University of Singapore, Singapore, Singapore; Abbott Laboratories, Abbott Park, IL
| | - B. C. Goh
- National Cancer Centre, Singapore, Singapore, Singapore; Nanyang Technological University, Singapore, Singapore; Singapore General Hospital, Singapore, Singapore; National University Hospital, Singapore, Singapore; National University of Singapore, Singapore, Singapore; Abbott Laboratories, Abbott Park, IL
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Bisdas S, Hartel M, Cheong LH, Koh TS, Vogl TJ. Prediction of subsequent hemorrhage in acute ischemic stroke using permeability CT imaging and a distributed parameter tracer kinetic model. J Neuroradiol 2007; 34:101-8. [PMID: 17383003 DOI: 10.1016/j.neurad.2007.02.003] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
PURPOSE Hemorrhagic transformation (HT) is a common consequence of infarction independent of thrombolytic therapy. Our purpose was to examine if permeability imaging in admission perfusion CT data of patients with acute stroke might indicate a subsequent HT by imaging the disrupted permeability barriers between blood and brain. MATERIALS AND METHODS A distributed parameter model analysis of the perfusion data were used to analyze the admission perfusion surveys of eight patients with HT of the initial infarct without thrombolysis. The perfusion findings of these patients were compared with those of eight age- and gender-matched patients from the initial group that did not present with HT. RESULTS The applied statistics for comparing the ischemic voxels with the contralateral healthy tissue showed significantly higher permeability-surface product (PS), extraction ratio (E), and extracellular extravascular space volume (V(EES)) in the ischemic voxels (P range, 0.05-0.0001). In the patients without HT, the PS, E and V(EES) values in the ischemic voxels were not significantly different from those in the normal region. CONCLUSION Our findings indicate that early perfusion CT physiological imaging in stroke is a promising tool for identifying patients with higher risk of HT and, thus, may serve to guide therapeutic options.
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Affiliation(s)
- S Bisdas
- Department of Diagnostic and Interventional Radiology, Johann Wolfgang Goethe University Hospital, Theodor Stern Kai 7, 60590 Frankfurt, Germany.
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Bisdas S, Hartel M, Cheong LH, Koh TS. Detection of early vessel leakiness in acute ischemic stroke using computed tomography perfusion may indicate hemorrhagic transformation. Acta Radiol 2007; 48:341-4. [PMID: 17453508 DOI: 10.1080/02841850601182170] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
This short communication presents significantly increased permeability in two patients with acute stroke, indicating an early blood-brain barrier disruption. Neither of the patients had undergone any thrombolytic therapy and hemorrhaged later. Increased permeability was assessed in both patients using a distributed-parameter model of capillary-tissue exchange. Our findings indicate that early physiologic imaging in stroke may identify patients with a high risk of hemorrhagic transformation by revealing pathologic vascular changes and, thus, guide therapeutic options.
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Affiliation(s)
- S Bisdas
- Department of Diagnostic and Interventional Radiology, Johann Wolfgang Goethe University Hospital, Frankfurt, Germany.
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Dennis Cheong LH, Markus Tan CK, Koh TS, Tchoyoson Lim CC, Bisdas S. Functional Imaging: Dynamic Contrast-Enhanced CT using a Distributed-Parameter Physiologic Model for Accessing Stroke and Intracranial Tumor. Conf Proc IEEE Eng Med Biol Soc 2007; 2006:294-7. [PMID: 17282171 DOI: 10.1109/iembs.2005.1616402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Functional imaging has the potential to be a practical and widely-available method of studying the pathphysiology of disease using modern CT and MRI technologies. With the high temporal resolution achievable by these technologies, a two-compartment distributed-parameter model, which more accurate represents the tracer concentration within the vascular space, was applied on two patients' data with intracranial tumor and stroke. The parametric maps successfully generated were more informative than the current commercial software packages and the commonly used lumped-parameter compartmental models.
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Affiliation(s)
- L H Dennis Cheong
- Center for Modeling and Control of Complex Systems, Nanyang Technological University, Singapore; Center for Signal Processing, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore. E-mail:
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Bisdas S, Gurung J, Konstantinou G, Lehnert T, Herzog C, Balzer JO, Mack MG, Koh TS, Vogl TJ. Akuter Schlaganfall: Effekt der Arteriellen Input Funktion auf Perfusionwerte und Ischämievolumetrie in der Perfusions-CT. ROFO-FORTSCHR RONTG 2007. [DOI: 10.1055/s-2007-977212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Bisdas S, Baghi M, Chambron-Pinho N, Smolarcz A, Knecht R, Herzog C, Mack MG, Koh TS, Vogl TJ. Perfusions-CT bei Kopfhalstumoren: Quantitative Perfusion- und Permeabilitätsmessungen bei Oropharynxkarzinomen, Oropharynxrezidiv und Lymphknotenmetastasen. ROFO-FORTSCHR RONTG 2007. [DOI: 10.1055/s-2007-976812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Abstract
Independent component analysis (ICA) was applied on dynamic contrast-enhanced computed tomography images of cerebral tumours to extract spatial component maps of the underlying vascular structures, which correspond to different haemodynamic phases as depicted by the passage of the contrast medium. The locations of arteries, veins and tumours can be separately identified on these spatial component maps. As the contrast enhancement behaviour of the cerebral tumour differs from the normal tissues, ICA yields a tumour component map that reveals the location and extent of the tumour. Tumour outlines can be generated using the tumour component maps, with relatively simple segmentation methods.
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Affiliation(s)
- T S Koh
- School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Ave, Singapore 639798.
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Koh TS, Tan CKM, Cheong LHD, Lim CCT. Cerebral perfusion mapping using a robust and efficient method for deconvolution analysis of dynamic contrast-enhanced images. Neuroimage 2006; 32:643-53. [PMID: 16682234 DOI: 10.1016/j.neuroimage.2006.03.042] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2006] [Accepted: 03/23/2006] [Indexed: 10/24/2022] Open
Abstract
Dynamic contrast-enhanced (DCE) imaging using MRI or CT is emerging as a promising tool for diagnostic imaging of cerebral disorders and the monitoring of tumor response to treatment. In this study, we present a robust and efficient deconvolution method based on a linearized model of the impulse residue function, which allows for the mapping of functional cerebral parameters such as cerebral blood flow, volume, mean transit time, and permeability. Monte Carlo simulation studies were performed to study the accuracy and stability of the proposed method, before applying it to clinical study cases of patients with cerebral tumors imaged using DCE CT. Functional parameter maps generated using the proposed method revealed the locations of the cerebral tumors and were found to be of sufficiently good clarity for marked regional differences in tissue vascularity and permeability to be assessed. In particular, tumor visualization and delineation were found to be better on the parameter maps that were indicative of the breakdown of the blood-brain barrier.
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Affiliation(s)
- T S Koh
- Center for Modeling and Control of Complex Systems, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Ave, Singapore 639798, Singapore.
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Zhang JL, Koh TS. On the Selection of Optimal Flip Angles for $T_1$Mapping of Breast Tumors With Dynamic Contrast-Enhanced Magnetic Resonance Imaging. IEEE Trans Biomed Eng 2006; 53:1209-14. [PMID: 16761851 DOI: 10.1109/tbme.2006.873391] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We present a method for selecting optimal flip angles for both precontrast and postcontrast T1 mapping of breast tumors using dynamic contrast-enhanced magnetic resonance imaging; and with the aim of improving accuracy in the estimation of contrast medium concentration. The proposed method can appropriately account for the different ranges of precontrst and postcontrast T1 values by the use of weighting functions, which also allow the flexibility to enhance the accuracy of certain T1 values, corresponding to the tissues of interest. Results of Monte Carlo simulations show that the proposed method could yield significantly lower errors in the estimation of contrast concentration, as compared with an existing approach.
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Affiliation(s)
- Jeff L Zhang
- Center for Modeling and Control of Complex Systems, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore.
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Abstract
Dynamic renal scintigraphy is an established method in nuclear medicine, commonly used for the assessment of renal function. In this paper, a biphasic model fitting method is proposed for simultaneous estimation of both vascular and parenchymal parameters from renal scintigraphic data. These parameters include the renal plasma flow, vascular and parenchymal mean transit times, and the glomerular extraction rate. Monte Carlo simulation was used to evaluate the stability and confidence of the parameter estimates obtained by the proposed biphasic method, before applying the method on actual patient study cases to compare with the conventional fitting approach and other established renal indices. The various parameter estimates obtained using the proposed method were found to be consistent with the respective pathologies of the study cases. The renal plasma flow and extraction rate estimated by the proposed method were in good agreement with those previously obtained using dynamic computed tomography and magnetic resonance imaging.
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Affiliation(s)
- T S Koh
- Center for Modeling and Control of Complex Systems, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore
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Koh TS, Cheong LHD, Tan CKM, Lim CCT. A distributed parameter model of cerebral blood-tissue exchange with account of capillary transit time distribution. Neuroimage 2006; 30:426-35. [PMID: 16246589 DOI: 10.1016/j.neuroimage.2005.09.032] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2005] [Revised: 09/10/2005] [Accepted: 09/19/2005] [Indexed: 11/28/2022] Open
Abstract
Quantitative estimates of physiological parameters associated with cerebral blood flow can be derived from the analysis of dynamic contrast-enhanced (DCE) images, using an appropriate model of the underlying tissue impulse residue function. The theoretical formulation of a distributed parameter model of tissue microcirculation, which accounts for the effects of capillary permeability and transit time distribution, is presented here. This model considers a statistical distribution of capillary-tissue units, each described by a distributed parameter model that accounts for convective transport within the capillary and transcapillary axial diffusion. Monte Carlo simulations were performed to study the confidence of the parameter estimates, and the model was used to analyze DCE CT images of patient study cases with metastatic cerebral tumors. The tumors were found to yield significantly higher estimates than normal tissues for the parameters associated with the extravasation of tracer and for the standard deviation of capillary transit times. The proposed model can be used with DCE imaging to study the microcirculatory characteristics of cerebral tumors.
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Affiliation(s)
- T S Koh
- Center for Modeling and Control of Complex Systems, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.
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Tan BJY, Sow CH, Koh TS, Chin KC, Wee ATS, Ong CK. Fabrication of Size-Tunable Gold Nanoparticles Array with Nanosphere Lithography, Reactive Ion Etching, and Thermal Annealing. J Phys Chem B 2005; 109:11100-9. [PMID: 16852354 DOI: 10.1021/jp045172n] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Two-dimensional ordered arrays of gold (Au) nanoparticles were fabricated using two different variants of the nanosphere lithography technique. First, ordered arrays of polystyrene nanospheres on Si substrate were used as deposition masks through which gold films were deposited by electron beam evaporation. After the removal of the nanospheres, an array of triangular Au nanodisks was left on the Si substrate. After thermal annealing at increasing temperature, systematic shape transition of the nanostructures from original triangular Au nanodisks to rounded nanoparticles was observed. This approach allows us to systematically vary the size and morphology of the particles. In the second and novel technique, we made use of reactive ion etching to simultaneously reduce the dimension of the masking nanospheres and create arrays of nanopores on the substrate prior to the deposition of the Au films. These samples were subsequently annealed, which resulted in size-tunable and ordered Au nanoparticle arrays with the nanoparticles nested in the nanopores of the templated substrate. With the nanoparticles anchored in the nanopores, the substrate could be useful as a template for growth of other nanomaterials.
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Affiliation(s)
- B J Y Tan
- Department of Physics, Blk S12, Faculty of Science, National University of Singapore, 2 Science Drive 3, Singapore 117542, USA
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Koh TS, Wu XY, Cheong LH, Lim CCT. Assessment of perfusion by dynamic contrast-enhanced imaging using a deconvolution approach based on regression and singular value decomposition. IEEE Trans Med Imaging 2004; 23:1532-1542. [PMID: 15575410 DOI: 10.1109/tmi.2004.837355] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The assessment of tissue perfusion by dynamic contrast-enhanced (DCE) imaging involves a deconvolution process. For analysis of DCE imaging data, we implemented a regression approach to select appropriate regularization parameters for deconvolution using the standard and generalized singular value decomposition methods. Monte Carlo simulation experiments were carried out to study the performance and to compare with other existing methods used for deconvolution analysis of DCE imaging data. The present approach is found to be robust and reliable at the levels of noise commonly encountered in DCE imaging, and for different models of the underlying tissue vasculature. The advantages of the present method, as compared with previous methods, include its efficiency of computation, ability to achieve adequate regularization to reproduce less noisy solutions, and that it does not require prior knowledge of the noise condition. The proposed method is applied on actual patient study cases with brain tumors and ischemic stroke, to illustrate its applicability as a clinical tool for diagnosis and assessment of treatment response.
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Affiliation(s)
- T S Koh
- School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798.
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Abstract
Instead of performing a numerical deconvolution, we propose to use a linear piecewise-continuous model of the renal impulse response function for parametric fitting of renal scintigraphy data, to obtain clinically useful renal parameters. The strengths of the present model are its simplicity and speed of computation, while not compromising on accuracy. Preliminary patient case studies show that the estimated parameters are in good agreement with a more elaborate model.
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Affiliation(s)
- Jeff L Zhang
- School of Electrical and Electronic Engineering, Center for Modeling and Control of Complex Systems, Nanyang Technological University, Singapore
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Cheong LH, Koh TS, Hou Z. An automatic approach for estimating bolus arrival time in dynamic contrast MRI using piecewise continuous regression models. Phys Med Biol 2003; 48:N83-8. [PMID: 12696805 DOI: 10.1088/0031-9155/48/5/403] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We present two regression models for the automatic estimation of bolus arrival times (BATs) in dynamic contrast MRI datasets. Results of Monte Carlo simulation experiments show that the means and standard deviations of the estimated BATs are within the sampling interval even in the presence of significant noise.
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Affiliation(s)
- L H Cheong
- School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798
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Koh TS, Cheong LH, Hou Z, Soh YC. A physiologic model of capillary-tissue exchange for dynamic contrast-enhanced imaging of tumor microcirculation. IEEE Trans Biomed Eng 2003; 50:159-67. [PMID: 12665029 DOI: 10.1109/tbme.2002.807657] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We present a multiple compartment, mammillary distributed-parameter model for capillary-tissue exchange, which can be implemented with dynamic contrast-enhanced imaging to study kinetic heterogeneity in tumors. The proposed n-compartment model consists of a vascular distributed-parameter compartment in direct exchange with a number (n - 1) of interstitial compartments. It is applied to a prostate tumor case study to illustrate the possible co-existence of two kinetically distinct compartments in the tumor, and the estimation of useful physiological parameters (such as perfusion, mean transit time, fractional volumes, and transfer and rate constants) associated with tissue microcirculation. The present model exhibits the convenient property of a separable impulse residue response function in time domain, which can be used to provide further insights and understanding on the physiological basis of tissue enhancement parameters commonly used for correlation studies with tumor histological diagnosis.
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Affiliation(s)
- T S Koh
- School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798.
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Abstract
We present a numerical deconvolution scheme for estimating regional blood flow and tissue retention functions by dynamic functional imaging. The present approach implements the Tikhonov-Miller regularization in general form, which allows for prior knowledge or assumptions to be incorporated during the deconvolution process, so as to stabilize the solution against variations due to noise. Appropriate approximations and simplifications in the context of functional imaging, were also introduced to ease numerical computations. Monte Carlo simulation experiments were carried out to study the applicability of the present approach and to compare with other deconvolution techniques previously studied.
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Affiliation(s)
- T S Koh
- School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798.
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Koh THHG, Koh TS. Harmony in the NICU. Arch Dis Child Fetal Neonatal Ed 2002; 86:F68. [PMID: 11815556 PMCID: PMC1721357 DOI: 10.1136/fn.86.1.f68-a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Koh TS, Jezioranski JJ, Haycocks T, Tong S, Heaton R, Yeung I. A practical approach to inverse planning for high-precision dose escalated conformal prostate radiotherapy. Phys Med Biol 2001; 46:1473-85. [PMID: 11384065 DOI: 10.1088/0031-9155/46/5/310] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The problem of choosing the best gantry angles and beam weights for dose-escalated conformal prostate treatment planning is formulated using a mixed-integer linear programming approach, to account for tumour dose homogeneity and dose-volume constraints. The formulation allows the number of beams to be restricted and for some of the beams to be compulsory. The present planning algorithm interfaces with and utilizes the three-dimensional planning capabilities of a commercial treatment planning system. A case study is illustrated, which represents a particularly challenging planning problem due to a large planning target volume and an unusually small bladder. Treatment plans with different numbers of beams are generated to compare with each other and with the standard six-field plan. Significant improvement is shown in the reduction of hot regions within the femoral heads and rectal wall, while not unduly compromising homogeneity constraints for the tumour.
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Affiliation(s)
- T S Koh
- Department of Radiation Physics, Princess Margaret Hospital, Toronto, ON, Canada
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Koh TS, Zeman V, Darko J, Lee TY, Milosevic MF, Haider M, Warde P, Yeung IW. The inclusion of capillary distribution in the adiabatic tissue homogeneity model of blood flow. Phys Med Biol 2001; 46:1519-38. [PMID: 11384068 DOI: 10.1088/0031-9155/46/5/313] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We have developed a non-invasive imaging tracer kinetic model for blood flow which takes into account the distribution of capillaries in tissue. Each individual capillary is assumed to follow the adiabatic tissue homogeneity model. The main strength of our new model is in its ability to quantify the functional distribution of capillaries by the standard deviation in the time taken by blood to pass through the tissue. We have applied our model to the human prostate and have tested two different types of distribution functions. Both distribution functions yielded very similar predictions for the various model parameters, and in particular for the standard deviation in transit time. Our motivation for developing this model is the fact that the capillary distribution in cancerous tissue is drastically different from in normal tissue. We believe that there is great potential for our model to be used as a prognostic tool in cancer treatment. For example, an accurate knowledge of the distribution in transit times might result in an accurate estimate of the degree of tumour hypoxia, which is crucial to the success of radiation therapy.
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Affiliation(s)
- T S Koh
- Department of Radiation Physics, Princess Margaret Hospital, Toronto, ON, Canada
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Abstract
Episcleral plaques are commonly used for the treatment of ocular tumours such as choroidal melanoma. Treatment planning involves the assignment of seeds to slots on the plaque to achieve a desired dose rate distribution. Seed assignment is rather straightforward if seeds are ordered on demand. However, the assignment task becomes tedious and laborious if the seeds have to be chosen from an existing stock of seeds with different activities. To date, this task has usually been performed by a human planner through trial and error. An algorithm has been developed to automate the task of seed assignment using a mixed-integer programming method. We also explore ways to simplify the problem such that the method becomes practical in most facilities. We have tested the method on three randomly chosen clinical cases from our past records, to show that the algorithm could yield solutions within a shorter time frame and with less deviation from the desired dose rate distributions, as compared with the solutions from a human counterpart.
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Affiliation(s)
- T S Koh
- Department of Clinical Physics, Princess Margaret Hospital, Toronto, Ontario, Canada.
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Koh TS, Peng RK, Klasing KC. Dietary copper level affects copper metabolism during lipopolysaccharide-induced immunological stress in chicks. Poult Sci 1996; 75:867-72. [PMID: 8805205 DOI: 10.3382/ps.0750867] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Two experiments were conducted to examine the effect of dietary Cu level on Cu metabolism during the acute phase response in broiler chicks with adequate (Experiment 1) or deficient (Experiment 2) Cu. Diets based on cornstarch and isolated soybean protein were used to formulate a basal diet, and basal diet plus either 5, 10, or 15 mg/kg additional Cu as either CuO or CuSO4. Each diet was fed to six pens of five chicks per pen (Experiment 1) or eight pens of five chicks (Experiment 2). Half of the chicks on each diet were injected with Salmonella typhymurium lipopolysaccharide (LPS) on alternate days. In Experiment 1, LPS significantly decreased daily gain, feed intake, and feed efficiency (P < 0.01) and increased the concentration of Cu in blood plasma (P < 0.01). In the uninjected birds, adding 5, 10, or 15 mg/kg Cu as CuO or 15 mg/kg Cu as CuSO4 increased the rate of gain over that of chicks fed the basal diet. In the birds challenged with LPS, 10 mg/kg Cu as CuO increased the rate of gain and efficiency compared to those of chicks fed the basal diet. Addition of CuSO4 to the diet of chicks challenged with LPS did not affect gain, intake, or feed efficiency compared to those of chicks fed the basal diet. Ceruloplasmin levels were higher in chicks challenged with LPS than in control chicks (P = 0.03), and this difference tended to be greater in chickens fed CuO than in chickens fed CuSO4 (P = 0.07). In chicks challenged with LPS, feeding CuO at all levels and feeding CuSO4 to give 10 or 15 mg/kg Cu increased ceruloplasmin levels above that of chicks fed the basal diet. Hepatic Mn superoxide dismutase (SOD) and Cu/Zn SOD were not influenced by dietary Cu level or source or LPS. Results of Experiment 2 were similar to those of Experiment 1 except that supplemental CuSO4 and CuO gave similar increases in gain and CuSO4 was more effective at increasing ceruloplasmin levels. Chicks given supplemental Cu had higher ceruloplasmin levels following challenge with LPS than Cu-deficient chicks fed the basal diet. Apparently, Cu requirements are higher for chicks experiencing an acute phase response than for healthy chicks.
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Affiliation(s)
- T S Koh
- Department of Feed and Nutritional Sciences, Kon-Kuk University, Seoul, Korea
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Koh TS, Fallon GD, Baklien A, Hearn MTW, Jackson WR. Synthesis and Structure of N,N'N"-Tris(2-hydroxyethyl)-N,N,N',N',N',N'-hexamethyl-2,2',2'-nitrilotris(ethylammonium) Trichloride. Aust J Chem 1996. [DOI: 10.1071/ch9960723] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The synthesis of N,N′,N″- tris(2-hydroxyethyl)-N,N,N′,N′,N″,N″-hexamethyl-2,2′,2″-nitrilotris( ethylammonium ) trichloride, a potential monomer for the preparation of polyurethane-based ion exchangers, is described and its structure reported based on X-ray diffraction data.
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Affiliation(s)
- A Mitsioulis
- Central Veterinary Laboratories, Primary Industries South Australia, Adelaide
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Koh TS, Choi WI, Han SJ. Effect of urinary nitrogenous compounds on the energy metabolism of bird. Asian Australas J Anim Sci 1992. [DOI: 10.5713/ajas.1992.267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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