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Puac-Polanco P, Guarnizo A, Cruz JP, Rodriguez FR, Torres CH. Intradural Extramedullary Tumors and Associated Syndromes. Neuroimaging Clin N Am 2023; 33:407-422. [PMID: 37356859 DOI: 10.1016/j.nic.2023.03.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/27/2023]
Abstract
Most intradural tumors are located within the intradural extramedullary compartment, and the most common tumors are schwannomas and meningiomas. Other less common neoplasms include neurofibroma, solitary fibrous tumor, myxopapillary ependymoma, lymphoma, metastatic leptomeningeal disease, malignant peripheral nerve sheath tumor, and paraganglioma. Patients usually present with gait ataxia, radicular pain, and motor and sensory deficits due to chronic compressive myelopathy or radiculopathy. MRI is the modality of choice for detecting and evaluating intradural extramedullary spinal tumors. This imaging technique helps narrow the differential diagnosis and therefore decide treatment.
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Affiliation(s)
- Paulo Puac-Polanco
- Department of Radiology, Radiation Oncology and Medical Physics, University of Ottawa, Box 232, General Campus Room 1466e, 501 Smyth Road, Ottawa, Ontario K1H 8L6, Canada
| | - Angela Guarnizo
- Radiology- Department of Diagnostic Imaging, Hospital Universitario Fundación Santa Fe de Bogota, Carrera 7 # 117-15, 220246 Bogotá-Colombia
| | - Juan Pablo Cruz
- Instituto de Neurocirugía Dr. Asenjo, Servicio de Neurorradiología Diagnóstica y Terapéutica, José Manuel Infante 553, Santiago, Providencia, Región Metropolitana, Chile
| | - Francisco Rivas Rodriguez
- Radiology, Division of Neuroradiology, University of Michigan, Michigan Medicine, C.S. Mott Children's Hospital, 1540 E Hospital Drive Rm 3-227, Ann Arbor, MI 48109-4252, USA
| | - Carlos H Torres
- Department of Radiology, Radiation Oncology and Medical Physics, University of Ottawa, Box 232, General Campus Room 1466e, 501 Smyth Road, Ottawa, Ontario K1H 8L6, Canada.
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Torres CH. Spinal Tumors. Neuroimaging Clin N Am 2023; 33:xvii-xviii. [PMID: 37356868 DOI: 10.1016/j.nic.2023.05.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/27/2023]
Affiliation(s)
- Carlos H Torres
- Department of Radiology, Radiation Oncology and Medical Physics, Box 232, General Campus Room 1466e, 501 Smyth Road, Ottawa, Ontario K1H 8L6, Canada.
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Rakocevic N, Alaslani OH, Torres CH. Case 303: Delayed Posthypoxic Leukoencephalopathy. Radiology 2022; 304:241-244. [PMID: 35727714 DOI: 10.1148/radiol.203756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
HISTORY A 54-year-old man was found by paramedics in his home face-down at his computer desk with a substantially reduced level of consciousness. He had not contacted his family for more than 50 hours. The patient lived alone and was a heavy smoker with a history of alcohol abuse. His medical history was otherwise unremarkable, and there was no history of cancer, psoriasis, or rheumatoid arthritis, nor was there a history of methotrexate administration. At presentation to the emergency department, he was mildly hypotensive and was experiencing hypercapnic respiratory failure and acute renal failure with rhabdomyolysis. His toxicology screen was mildly positive for opiates. He received naloxone (Narcan; Emergent) with minimal effect. An unenhanced CT scan of the head was obtained. Of note, this patient's presentation predated the COVID-19 pandemic. He was admitted to the intensive care unit for decreased level of consciousness and respiratory failure. The decreased level of consciousness was thought to be secondary to seizure, as he developed seizurelike movements prior to intubation, probably in the context of intoxication or alcohol withdrawal. Electroencephalography revealed moderate bilateral cerebral dysfunction and encephalopathy, with no evidence of nonconvulsive seizures. He had a short course of intermittent hemodialysis and was discharged home 8 days later with an appointment for neurology follow-up. At discharge, he was at his cognitive and functional baseline. Approximately 3 weeks later, the patient was brought back to the emergency department for progressive confusion and decrease in balance. He became apathetic with reduced psychomotor activity and was no longer able to perform basic daily activities, such as cooking or bathing. He displayed bizarre behavior, such as staring at a wall for hours, and was somnolent, irritable, and inattentive. He eventually became incontinent of urine and stool. Results of a neurologic examination of the cranial nerves, motor function, sensation, and reflexes were normal. The results of blood work-up were grossly normal, and the results of an extensive toxicology work-up were negative. Repeat head CT was performed. MRI was ordered to further investigate the patient's encephalopathic presentation.
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Affiliation(s)
- Natalie Rakocevic
- From the Department of Radiology, University of Ottawa, 501 Smyth Rd, Ottawa, ON, Canada K1H 8L6 (N.R., O.H.A., C.H.T.), and Department of Medical Imaging, The Ottawa Hospital, Ottawa, Canada (O.H.A., C.H.T.)
| | - Ohoud H Alaslani
- From the Department of Radiology, University of Ottawa, 501 Smyth Rd, Ottawa, ON, Canada K1H 8L6 (N.R., O.H.A., C.H.T.), and Department of Medical Imaging, The Ottawa Hospital, Ottawa, Canada (O.H.A., C.H.T.)
| | - Carlos H Torres
- From the Department of Radiology, University of Ottawa, 501 Smyth Rd, Ottawa, ON, Canada K1H 8L6 (N.R., O.H.A., C.H.T.), and Department of Medical Imaging, The Ottawa Hospital, Ottawa, Canada (O.H.A., C.H.T.)
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Rakocevic N, Alaslani OH, Torres CH. Case 303. Radiology 2022; 302:722-723. [PMID: 35196176 DOI: 10.1148/radiol.203755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
History A 54-year-old man was found by paramedics in his home face-down at his computer desk with a substantially reduced level of consciousness. He had not contacted his family for more than 50 hours. The patient lived alone and was a heavy smoker with a history of alcohol abuse. His medical history was otherwise unremarkable, and there was no history of cancer, psoriasis, or rheumatoid arthritis, nor was there a history of methotrexate administration. On presentation to the emergency department, he was mildly hypotensive and was experiencing hypercapnic respiratory failure and acute renal failure with rhabdomyolysis. His toxicology screen was mildly positive for opiates. He received naloxone (Narcan; Emergent) with minimal effect. An unenhanced CT scan of the head was obtained (Fig 1A). Of note, this patient's presentation predated the COVID-19 pandemic. He was admitted to the intensive care unit for decreased level of consciousness and respiratory failure. The decreased level of consciousness was thought to be secondary to seizure, as he developed seizurelike movements prior to intubation, probably in the context of intoxication or alcohol withdrawal. Electroencephalography revealed moderate bilateral cerebral dysfunction and encephalopathy, with no evidence of nonconvulsive seizures. He had a short course of intermittent hemodialysis and was discharged home 8 days later with an appointment for neurology follow-up. At discharge, he was at his cognitive and functional baseline. Approximately 3 weeks later, the patient was brought back to the emergency department for progressive confusion and decrease in balance. He became apathetic with reduced psychomotor activity and was no longer able to perform basic daily activities, such as cooking or bathing. He displayed bizarre behavior, such as staring at a wall for hours, and was somnolent, irritable, and inattentive. He eventually became incontinent of urine and stool. Results of a neurologic examination of the cranial nerves, motor function, sensation, and reflexes were normal. The results of blood work-up were grossly normal, and the results of an extensive toxicology work-up were negative. Repeat head CT was performed (Fig 1B). MRI was ordered to further investigate the patient's encephalopathic presentation (Figs 2-3).
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Affiliation(s)
- Natalie Rakocevic
- From the Department of Radiology, University of Ottawa, 501 Smyth Rd, Ottawa, ON, Canada K1H 8L6 (N.R., O.H.A., C.H.T.), and Department of Medical Imaging, The Ottawa Hospital, Ottawa, Canada (O.H.A., C.H.T.)
| | - Ohoud H Alaslani
- From the Department of Radiology, University of Ottawa, 501 Smyth Rd, Ottawa, ON, Canada K1H 8L6 (N.R., O.H.A., C.H.T.), and Department of Medical Imaging, The Ottawa Hospital, Ottawa, Canada (O.H.A., C.H.T.)
| | - Carlos H Torres
- From the Department of Radiology, University of Ottawa, 501 Smyth Rd, Ottawa, ON, Canada K1H 8L6 (N.R., O.H.A., C.H.T.), and Department of Medical Imaging, The Ottawa Hospital, Ottawa, Canada (O.H.A., C.H.T.)
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Nguyen TB, Melkus G, Taccone M, Moldovan ID, Ghinda D, Gotfrit R, Torres CH, Zakhari N, Chakraborty S, Woulfe J, Jansen G, McInnes MD, Thornhill RE, Cameron I, AlKherayf F. Preoperative Determination of Isocitrate Dehydrogenase Mutation in Gliomas Using Spectral Editing MRS: A Prospective Study. J Magn Reson Imaging 2020; 53:416-426. [PMID: 32940938 DOI: 10.1002/jmri.27366] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [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: 06/20/2020] [Revised: 08/22/2020] [Accepted: 08/27/2020] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND The edited magnetic resonance spectroscopy (MRS) technique has not yet been formally evaluated for the in vivo detection of 2-hydroxyglutarate (2-HG) in patients with gliomas of various grades. PURPOSE To evaluate the diagnostic accuracy of edited MRS in the preoperative identification of the isocitrate dehydrogenase (IDH) mutation status in patients with gliomas. STUDY TYPE Prospective. POPULATION Fifty-eight subjects (31 glioblastomas, 27 grade II and III gliomas). FIELD STRENGTH/SEQUENCE Mescher-Garwood (MEGA)-PRESS and routine clinical brain tumor MR sequences were used at 3T. ASSESSMENT Data were analyzed using an advanced method for accurate, robust, and efficient spectral fitting (AMARES) from jMRUI software. The amplitudes of the 2-HG, N-acetyl-aspartate (NAA), choline (Cho), and creatine/phosphocreatine (Cr) resonances were calculated with their associated Cramer-Rao lower bound (CRLB). The IDH1 R132H mutation status was assessed by immunohistochemistry for all patients. Patients with grades II and III gliomas with negative immunohistochemistry underwent DNA sequencing to further interrogate IDH mutation status. STATISTICAL TEST The differences in 2-HG amplitudes, 2-HG/NAA, 2-HG/Cho, and 2-HG/Cr between IDH-mutant and IDH-wildtype gliomas were assessed using Mann-Whitney U-tests. Receiver operating characteristic curve analysis was performed to evaluate the diagnostic accuracy of each parameter. RESULTS The 2-HG amplitudes, 2-HG/NAA, and 2-HG/Cho were higher for IDH-mutant gliomas than IDH-wildtype gliomas (P < 0.007). Using a CRLB threshold <30%, a 2-HG cutoff greater than 0 had a sensitivity of 80% (95% confidence interval [CI]: 52-96%) and a specificity of 81% (95% CI: 54-96%) in identifying IDH-mutant gliomas. In the subset of patients with grades II and III gliomas, the sensitivity was 80% (95% CI: 52-96%) and specificity was 100% (95% CI: 40-100%). Among 2-HG ratios, the highest AUC for the identification of IDH mutant status was achieved using the 2-HG/NAA (AUC = 0.8, 95% CI 0.67-.89). DATA CONCLUSION Preoperative edited MRS appears to be able to help identify IDH-mutant gliomas with high specificity. Level of Evidence 1 Technical Efficacy Stage 2 J. MAGN. RESON. IMAGING 2021;53:416-426.
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Affiliation(s)
- Thanh B Nguyen
- Department of Radiology, The Ottawa Hospital, Ottawa, Ontario, Canada.,University of Ottawa, Ottawa, Ontario, Canada.,The Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - Gerd Melkus
- Department of Radiology, The Ottawa Hospital, Ottawa, Ontario, Canada.,University of Ottawa, Ottawa, Ontario, Canada.,The Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - Michael Taccone
- University of Ottawa, Ottawa, Ontario, Canada.,Division of Neurosurgery, Department of Surgery, The Ottawa Hospital, Ottawa, Ontario, Canada
| | - Ioana D Moldovan
- The Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.,Division of Neurosurgery, Department of Surgery, The Ottawa Hospital, Ottawa, Ontario, Canada
| | - Diana Ghinda
- University of Ottawa, Ottawa, Ontario, Canada.,Division of Neurosurgery, Department of Surgery, The Ottawa Hospital, Ottawa, Ontario, Canada
| | - Ryan Gotfrit
- University of Ottawa, Ottawa, Ontario, Canada.,Division of Neurology, Department of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Carlos H Torres
- Department of Radiology, The Ottawa Hospital, Ottawa, Ontario, Canada.,University of Ottawa, Ottawa, Ontario, Canada
| | - Nader Zakhari
- Department of Radiology, The Ottawa Hospital, Ottawa, Ontario, Canada.,University of Ottawa, Ottawa, Ontario, Canada
| | - Santanu Chakraborty
- Department of Radiology, The Ottawa Hospital, Ottawa, Ontario, Canada.,University of Ottawa, Ottawa, Ontario, Canada
| | - John Woulfe
- University of Ottawa, Ottawa, Ontario, Canada.,The Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.,Department of Pathology and Laboratory Medicine, The Ottawa Hospital, Ottawa, Ontario, Canada
| | - Gerard Jansen
- University of Ottawa, Ottawa, Ontario, Canada.,Department of Pathology and Laboratory Medicine, The Ottawa Hospital, Ottawa, Ontario, Canada
| | - Matthew Df McInnes
- Department of Radiology, The Ottawa Hospital, Ottawa, Ontario, Canada.,University of Ottawa, Ottawa, Ontario, Canada.,The Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - Rebecca E Thornhill
- Department of Radiology, The Ottawa Hospital, Ottawa, Ontario, Canada.,University of Ottawa, Ottawa, Ontario, Canada
| | - Ian Cameron
- Department of Radiology, The Ottawa Hospital, Ottawa, Ontario, Canada.,University of Ottawa, Ottawa, Ontario, Canada
| | - Fahad AlKherayf
- University of Ottawa, Ottawa, Ontario, Canada.,The Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.,Division of Neurosurgery, Department of Surgery, The Ottawa Hospital, Ottawa, Ontario, Canada
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Zakhari N, Taccone MS, Torres CH, Chakraborty S, Sinclair J, Woulfe J, Jansen GH, Cron GO, Thornhill RE, McInnes MDF, Nguyen TB. Prospective comparative diagnostic accuracy evaluation of dynamic contrast-enhanced (DCE) vs. dynamic susceptibility contrast (DSC) MR perfusion in differentiating tumor recurrence from radiation necrosis in treated high-grade gliomas. J Magn Reson Imaging 2019; 50:573-582. [PMID: 30614146 DOI: 10.1002/jmri.26621] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [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: 09/12/2018] [Revised: 12/04/2018] [Accepted: 12/05/2018] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND The appearance of a new enhancing lesion after surgery and chemoradiation for high-grade glioma (HGG) presents a common diagnostic dilemma. Histopathological analysis remains the reference standard in this situation. PURPOSE To prospectively compare the diagnostic accuracy of dynamic contrast-enhanced (DCE) vs. dynamic susceptibility contrast (DSC) in differentiating tumor recurrence (TR) from radiation necrosis (RN). STUDY TYPE Prospective diagnostic accuracy study. POPULATION In all, 98 consecutive treated HGG patients with new enhancing lesion. We excluded 32 patients due to inadequate follow-up or technical limitation. FIELD STRENGTH/SEQUENCE 3 T DCE and DSC MR. ASSESSMENT Histogram and hot-spot analysis of cerebral blood volume (CBV), corrected CBV, Ktrans , area under the curve (AUC), and plasma volume (Vp). The reference standard of TR and/or RN was determined by histopathology in 43 surgically resected lesions or by clinical/imaging follow-up in the rest. STATISTICAL TESTS Mann-Whitney U-tests, receiver operating characteristic (ROC) curve, and logistic regression analysis. RESULTS A total of 68 lesions were included. There were 37 TR, 28 RN, and three lesions with equal proportions of TR and RN. TR had significantly higher CBV, corrected CBV, CBV ratio, corrected CBV ratio, AUC ratio, and Vp ratio (P < 0.05) than RN on hot-spot analysis. CBV had the highest diagnostic accuracy (AUROC 0.71). On histogram analysis, TR had higher CBV and corrected CBV maximal value compared with RN (P = 0.006, AUROC = 0.70). Only CBV on hot-spot analysis remained significant after correction for multiple comparison, with no significant improvement in diagnostic accuracy when using a combination of parameters (AUROC 0.71 vs. 0.76, P = 0.24). DATA CONCLUSION DSC-derived CBV is the most accurate perfusion parameter in differentiating TR and RN. DSC and DCE-derived parameters reflecting the blood volume in an enhancing lesion are more accurate than the DCE-derived parameter Ktrans . Clinical practice may be best guided by blood volume measurements, rather than permeability assessment for differentiation of TR from RN. LEVEL OF EVIDENCE 1 Technical Efficacy Stage: 4 J. Magn. Reson. Imaging 2019;50:573-582.
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Affiliation(s)
- Nader Zakhari
- University of Ottawa, Ottawa, Ontario, Canada.,Ottawa Hospital, Ottawa, Ontario, Canada
| | - Michael S Taccone
- University of Ottawa, Ottawa, Ontario, Canada.,Laboratory Medicine & Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Carlos H Torres
- University of Ottawa, Ottawa, Ontario, Canada.,Ottawa Hospital, Ottawa, Ontario, Canada
| | - Santanu Chakraborty
- University of Ottawa, Ottawa, Ontario, Canada.,Ottawa Hospital, Ottawa, Ontario, Canada
| | - John Sinclair
- University of Ottawa, Ottawa, Ontario, Canada.,Ottawa Hospital, Ottawa, Ontario, Canada
| | - John Woulfe
- University of Ottawa, Ottawa, Ontario, Canada.,Ottawa Hospital, Ottawa, Ontario, Canada
| | - Gerard H Jansen
- University of Ottawa, Ottawa, Ontario, Canada.,Ottawa Hospital, Ottawa, Ontario, Canada
| | - Greg O Cron
- University of Ottawa, Ottawa, Ontario, Canada.,Ottawa Hospital, Ottawa, Ontario, Canada.,Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | | | - Matthew D F McInnes
- University of Ottawa, Ottawa, Ontario, Canada.,Ottawa Hospital, Ottawa, Ontario, Canada.,Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - Thanh B Nguyen
- University of Ottawa, Ottawa, Ontario, Canada.,Ottawa Hospital, Ottawa, Ontario, Canada
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Varona ME, Díaz SM, Briceño L, Sánchez-Infante CI, Torres CH, Palma RM, Groot H, Idrovo AJ. [Determining social factors related to pesticide poisoning among rice farmers in Colombia]. Rev Salud Publica (Bogota) 2017; 18:617-629. [PMID: 28453066 DOI: 10.15446/rsap.v18n4.52617] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 05/22/2016] [Indexed: 11/09/2022] Open
Abstract
Objective Large quantities of pesticides are used in rice crops. The aim of this study is to characterize how farmers are exposed to pesticides and subsequent poisoning. Materials and Methods A multilevel (individual and community) multi-method study, which included ethnographic and survey methods, as well as measurement of pesticides in water and human samples, was performed. Results The production process is described and the main risk factors are presented. Pesticides are considered the greatest danger at work and at their homes. Workers have poor working conditions and are not protected by the system of occupational risks. Azinphos-methyl, endosulfan, β-BHC, bromophos-methyl, bromophos-ethyl and 2,4- DDT were found in water samples. The survey included 381 workers with mild (12.86 %), moderate (67.98 %) and severe (5.51 %) poisonings respectively. Severe cases presented lower levels of education, lower levels of health care access to the contributory regimen of the Colombian social security system and higher incidence of cardiovascular disease, diabetes, herpes or other viral infections. Conclusion There are precarious working conditions that favor exposure to pesticides correlated to the exclusion of farmers from the occupational risk system, to poverty and to poor education. It is urgent to include these workers to the system of occupational risk system and to improve their living conditions, thus reducing unsafe practices when handling pesticides.
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Affiliation(s)
| | | | | | | | | | | | | | - Alvaro J Idrovo
- Universidad Manuela Beltrán, Bucaramanga, Santander, Colombia
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Nguyen TB, Cron GO, Bezzina K, Perdrizet K, Torres CH, Chakraborty S, Woulfe J, Jansen GH, Thornhill RE, Zanette B, Cameron IG. Correlation of Tumor Immunohistochemistry with Dynamic Contrast-Enhanced and DSC-MRI Parameters in Patients with Gliomas. AJNR Am J Neuroradiol 2016; 37:2217-2223. [PMID: 27585700 DOI: 10.3174/ajnr.a4908] [Citation(s) in RCA: 22] [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] [Received: 02/20/2016] [Accepted: 07/01/2016] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Tumor CBV is a prognostic and predictive marker for patients with gliomas. Tumor CBV can be measured noninvasively with different MR imaging techniques; however, it is not clear which of these techniques most closely reflects histologically-measured tumor CBV. Our aim was to investigate the correlations between dynamic contrast-enhanced and DSC-MR imaging parameters and immunohistochemistry in patients with gliomas. MATERIALS AND METHODS Forty-three patients with a new diagnosis of glioma underwent a preoperative MR imaging examination with dynamic contrast-enhanced and DSC sequences. Unnormalized and normalized cerebral blood volume was obtained from DSC MR imaging. Two sets of plasma volume and volume transfer constant maps were obtained from dynamic contrast-enhanced MR imaging. Plasma volume obtained from the phase-derived vascular input function and bookend T1 mapping (Vp_Φ) and volume transfer constant obtained from phase-derived vascular input function and bookend T1 mapping (Ktrans_Φ) were determined. Plasma volume obtained from magnitude-derived vascular input function (Vp_SI) and volume transfer constant obtained from magnitude-derived vascular input function (Ktrans_SI) were acquired, without T1 mapping. Using CD34 staining, we measured microvessel density and microvessel area within 3 representative areas of the resected tumor specimen. The Mann-Whitney U test was used to test for differences according to grade and degree of enhancement. The Spearman correlation was performed to determine the relationship between dynamic contrast-enhanced and DSC parameters and histopathologic measurements. RESULTS Microvessel area, microvessel density, dynamic contrast-enhanced, and DSC-MR imaging parameters varied according to the grade and degree of enhancement (P < .05). A strong correlation was found between microvessel area and Vp_Φ and between microvessel area and unnormalized blood volume (rs ≥ 0.61). A moderate correlation was found between microvessel area and normalized blood volume, microvessel area and Vp_SI, microvessel area and Ktrans_Φ, microvessel area and Ktrans_SI, microvessel density and Vp_Φ, microvessel density and unnormalized blood volume, and microvessel density and normalized blood volume (0.44 ≤ rs ≤ 0.57). A weaker correlation was found between microvessel density and Ktrans_Φ and between microvessel density and Ktrans_SI (rs ≤ 0.41). CONCLUSIONS With dynamic contrast-enhanced MR imaging, use of a phase-derived vascular input function and bookend T1 mapping improves the correlation between immunohistochemistry and plasma volume, but not between immunohistochemistry and the volume transfer constant. With DSC-MR imaging, normalization of tumor CBV could decrease the correlation with microvessel area.
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Affiliation(s)
- T B Nguyen
- From the Departments of Radiology (T.B.N., G.O.C., C.H.T., R.E.T., I.G.C., S.C.)
| | - G O Cron
- From the Departments of Radiology (T.B.N., G.O.C., C.H.T., R.E.T., I.G.C., S.C.)
| | - K Bezzina
- Psychiatry (K.B.), The Ottawa Hospital, University of Ottawa, The Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | | | - C H Torres
- From the Departments of Radiology (T.B.N., G.O.C., C.H.T., R.E.T., I.G.C., S.C.)
| | - S Chakraborty
- From the Departments of Radiology (T.B.N., G.O.C., C.H.T., R.E.T., I.G.C., S.C.)
| | | | | | - R E Thornhill
- From the Departments of Radiology (T.B.N., G.O.C., C.H.T., R.E.T., I.G.C., S.C.)
| | - B Zanette
- Department of Medical Biophysics (B.Z.), University of Toronto, Toronto, Ontario, Canada
| | - I G Cameron
- From the Departments of Radiology (T.B.N., G.O.C., C.H.T., R.E.T., I.G.C., S.C.).,Medical Physics (I.G.C.)
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Nguyen TB, Cron GO, Perdrizet K, Bezzina K, Torres CH, Chakraborty S, Woulfe J, Jansen GH, Sinclair J, Thornhill RE, Foottit C, Zanette B, Cameron IG. Comparison of the Diagnostic Accuracy of DSC- and Dynamic Contrast-Enhanced MRI in the Preoperative Grading of Astrocytomas. AJNR Am J Neuroradiol 2015; 36:2017-22. [PMID: 26228886 DOI: 10.3174/ajnr.a4398] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Accepted: 03/24/2015] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Dynamic contrast-enhanced MR imaging parameters can be biased by poor measurement of the vascular input function. We have compared the diagnostic accuracy of dynamic contrast-enhanced MR imaging by using a phase-derived vascular input function and "bookend" T1 measurements with DSC MR imaging for preoperative grading of astrocytomas. MATERIALS AND METHODS This prospective study included 48 patients with a new pathologic diagnosis of an astrocytoma. Preoperative MR imaging was performed at 3T, which included 2 injections of 5-mL gadobutrol for dynamic contrast-enhanced and DSC MR imaging. During dynamic contrast-enhanced MR imaging, both magnitude and phase images were acquired to estimate plasma volume obtained from phase-derived vascular input function (Vp_Φ) and volume transfer constant obtained from phase-derived vascular input function (K(trans)_Φ) as well as plasma volume obtained from magnitude-derived vascular input function (Vp_SI) and volume transfer constant obtained from magnitude-derived vascular input function (K(trans)_SI). From DSC MR imaging, corrected relative CBV was computed. Four ROIs were placed over the solid part of the tumor, and the highest value among the ROIs was recorded. A Mann-Whitney U test was used to test for difference between grades. Diagnostic accuracy was assessed by using receiver operating characteristic analysis. RESULTS Vp_ Φ and K(trans)_Φ values were lower for grade II compared with grade III astrocytomas (P < .05). Vp_SI and K(trans)_SI were not significantly different between grade II and grade III astrocytomas (P = .08-0.15). Relative CBV and dynamic contrast-enhanced MR imaging parameters except for K(trans)_SI were lower for grade III compared with grade IV (P ≤ .05). In differentiating low- and high-grade astrocytomas, we found no statistically significant difference in diagnostic accuracy between relative CBV and dynamic contrast-enhanced MR imaging parameters. CONCLUSIONS In the preoperative grading of astrocytomas, the diagnostic accuracy of dynamic contrast-enhanced MR imaging parameters is similar to that of relative CBV.
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Affiliation(s)
- T B Nguyen
- From the Departments of Radiology (T.B.N., G.O.C., C.H.T., R.E.T., I.G.C., S.C.)
| | - G O Cron
- From the Departments of Radiology (T.B.N., G.O.C., C.H.T., R.E.T., I.G.C., S.C.)
| | | | - K Bezzina
- Faculty of Medicine (K.B.), Ottawa Hospital, University of Ottawa, Ottawa, Ontario, Canada
| | - C H Torres
- From the Departments of Radiology (T.B.N., G.O.C., C.H.T., R.E.T., I.G.C., S.C.)
| | - S Chakraborty
- From the Departments of Radiology (T.B.N., G.O.C., C.H.T., R.E.T., I.G.C., S.C.)
| | | | | | - J Sinclair
- Surgery, Division of Neurosurgery (J.S.)
| | - R E Thornhill
- From the Departments of Radiology (T.B.N., G.O.C., C.H.T., R.E.T., I.G.C., S.C.)
| | | | - B Zanette
- Department of Medical Biophysics (B.Z.), University of Toronto, Toronto, Ontario, Canada
| | - I G Cameron
- From the Departments of Radiology (T.B.N., G.O.C., C.H.T., R.E.T., I.G.C., S.C.) Medical Physics (C.F., I.G.C.)
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Nguyen TB, Cron GO, Mercier JF, Foottit C, Torres CH, Chakraborty S, Woulfe J, Jansen GH, Caudrelier JM, Sinclair J, Hogan MJ, Thornhill RE, Cameron IG. Preoperative prognostic value of dynamic contrast-enhanced MRI-derived contrast transfer coefficient and plasma volume in patients with cerebral gliomas. AJNR Am J Neuroradiol 2015; 36:63-9. [PMID: 24948500 DOI: 10.3174/ajnr.a4006] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [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
BACKGROUND AND PURPOSE The prognostic value of dynamic contrast-enhanced MR imaging-derived plasma volume obtained in tumor and the contrast transfer coefficient has not been well-established in patients with gliomas. We determined whether plasma volume and contrast transfer coefficient in tumor correlated with survival in patients with gliomas in addition to other factors such as age, type of surgery, preoperative Karnofsky score, contrast enhancement, and histopathologic grade. MATERIALS AND METHODS This prospective study included 46 patients with a new pathologically confirmed diagnosis of glioma. The contrast transfer coefficient and plasma volume obtained in tumor maps were calculated directly from the signal-intensity curve without T1 measurements, and values were obtained from multiple small ROIs placed within tumors. Survival curve analysis was performed by dichotomizing patients into groups of high and low contrast transfer coefficient and plasma volume. Univariate analysis was performed by using dynamic contrast-enhanced parameters and clinical factors. Factors that were significant on univariate analysis were entered into multivariate analysis. RESULTS For all patients with gliomas, survival was worse for groups of patients with high contrast transfer coefficient and plasma volume obtained in tumor (P < .05). In subgroups of high- and low-grade gliomas, survival was worse for groups of patients with high contrast transfer coefficient and plasma volume obtained in tumor (P < .05). Univariate analysis showed that factors associated with lower survival were age older than 50 years, low Karnofsky score, biopsy-only versus resection, marked contrast enhancement versus no/mild enhancement, high contrast transfer coefficient, and high plasma volume obtained in tumor (P < .05). In multivariate analysis, a low Karnofsky score, biopsy versus resection in combination with marked contrast enhancement, and a high contrast transfer coefficient were associated with lower survival rates (P < .05). CONCLUSIONS In patients with glioma, those with a high contrast transfer coefficient have lower survival than those with low parameters.
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Affiliation(s)
- T B Nguyen
- From the Departments of Diagnostic Imaging (T.B.N., G.O.C., C.H.T., R.E.T., I.G.C., S.C., J.M.C.)
| | - G O Cron
- From the Departments of Diagnostic Imaging (T.B.N., G.O.C., C.H.T., R.E.T., I.G.C., S.C., J.M.C.)
| | - J F Mercier
- Department of Radiology (J.F.M.), Hôpital de Hull, Gatineau, Québec, Canada
| | | | - C H Torres
- From the Departments of Diagnostic Imaging (T.B.N., G.O.C., C.H.T., R.E.T., I.G.C., S.C., J.M.C.)
| | - S Chakraborty
- From the Departments of Diagnostic Imaging (T.B.N., G.O.C., C.H.T., R.E.T., I.G.C., S.C., J.M.C.)
| | | | | | - J M Caudrelier
- From the Departments of Diagnostic Imaging (T.B.N., G.O.C., C.H.T., R.E.T., I.G.C., S.C., J.M.C.)
| | - J Sinclair
- Surgery, Division of Neurosurgery (J.S.)
| | - M J Hogan
- Medicine, Division of Neurology (M.J.H.), The Ottawa Hospital, University of Ottawa, Ottawa, Ontario, Canada
| | - R E Thornhill
- From the Departments of Diagnostic Imaging (T.B.N., G.O.C., C.H.T., R.E.T., I.G.C., S.C., J.M.C.)
| | - I G Cameron
- From the Departments of Diagnostic Imaging (T.B.N., G.O.C., C.H.T., R.E.T., I.G.C., S.C., J.M.C.) Medical Physics (C.F., I.G.C.)
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Kalidindi N, Torres CH, Michaud J, Zwicker JC. Primitive neuroectodermal tumor presenting with diffuse leptomeningeal involvement in a 55-year-old woman: a case report and brief summary of current diagnostic tests and treatment. Case Rep Oncol 2014; 7:471-7. [PMID: 25202261 PMCID: PMC4154191 DOI: 10.1159/000365414] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Primitive neuroectodermal tumors (PNETs) are typically present as masses in children and adolescents, but rarely in adults. Diagnoses, management strategies, and prognostication factors are not well established in adult cases of PNETs. We describe the case of a central nervous system PNET diagnosed in a 55-year-old woman presenting with a sudden onset of symptoms consisting of increased intracranial pressure and findings of diffuse leptomeningeal enhancement and a small medullary lesion seen on MRI. Amongst the small database of PNETs diagnosed in adults, our case report stands out as one of few cases describing a primarily leptomeningeal PNET diagnosed on biopsy. We also review the literature on PNETs presenting with diffuse leptomeningeal disease and the treatment of PNETs in the adult population.
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Affiliation(s)
- Navya Kalidindi
- Department of Neurology, University of Ottawa, The Ottawa Hospital, CHEO, Ottawa, Ont., Canada
| | - Carlos H Torres
- Department of Radiology, University of Ottawa, The Ottawa Hospital, CHEO, Ottawa, Ont., Canada
| | - Jean Michaud
- Department of Pathology and Laboratory Medicine, University of Ottawa, The Ottawa Hospital, CHEO, Ottawa, Ont., Canada
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12
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Thornhill RE, Lum C, Jaberi A, Stefanski P, Torres CH, Momoli F, Petrcich W, Dowlatshahi D. Can shape analysis differentiate free-floating internal carotid artery thrombus from atherosclerotic plaque in patients evaluated with CTA for stroke or transient ischemic attack? Acad Radiol 2014; 21:345-54. [PMID: 24507422 DOI: 10.1016/j.acra.2013.11.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 10/22/2013] [Accepted: 11/08/2013] [Indexed: 11/16/2022]
Abstract
RATIONALE AND OBJECTIVES Patients presenting with transient ischemic attack or stroke may have symptom-related lesions on acute computed tomography angiography (CTA) such as free-floating intraluminal thrombus (FFT). It is difficult to distinguish FFT from carotid plaque, but the distinction is critical as management differs. By contouring the shape of these vascular lesions ("virtual endarterectomy"), advanced morphometric analysis can be performed. The objective of our study is to determine whether quantitative shape analysis can accurately differentiate FFT from atherosclerotic plaque. MATERIALS AND METHODS We collected 23 consecutive cases of suspected carotid FFT seen on CTA (13 men, 65 ± 10 years; 10 women, 65.5 ± 8.8 years). True-positive FFT cases (FFT+) were defined as filling defects resolving with anticoagulant therapy versus false-positives (FFT-), which remained unchanged. Lesion volumes were extracted from CTA images and quantitative shape descriptors were computed. The five most discriminative features were used to construct receiver operator characteristic (ROC) curves and to generate three machine-learning classifiers. Average classification accuracy was determined by cross-validation. RESULTS Follow-up imaging confirmed sixteen FFT+ and seven FFT- cases. Five shape descriptors delineated FFT+ from FFT- cases. The logistic regression model produced from combining all five shape features demonstrated a sensitivity of 87.5% and a specificity of 71.4% with an area under the ROC curve = 0.85 ± 0.09. Average accuracy for each classifier ranged from 65.2%-76.4%. CONCLUSIONS We identified five quantitative shape descriptors of carotid FFT. This shape "signature" shows potential for supplementing conventional lesion characterization in cases of suspected FFT.
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Affiliation(s)
- Rebecca E Thornhill
- Department of Radiology, University of Ottawa, Ottawa, Ontario, Canada; Department of Medical Imaging, The Ottawa Hospital, 1053 Carling Ave, Ottawa, Ontario K1Y 4E9, Canada; Clinical Epidemiology Program/Methods Centre, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.
| | - Cheemun Lum
- Department of Radiology, University of Ottawa, Ottawa, Ontario, Canada; Department of Medical Imaging, The Ottawa Hospital, 1053 Carling Ave, Ottawa, Ontario K1Y 4E9, Canada; Clinical Epidemiology Program/Methods Centre, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - Arash Jaberi
- Department of Radiology, University of Ottawa, Ottawa, Ontario, Canada; Department of Medical Imaging, The Ottawa Hospital, 1053 Carling Ave, Ottawa, Ontario K1Y 4E9, Canada
| | - Pawel Stefanski
- Department of Radiology, University of Ottawa, Ottawa, Ontario, Canada; Department of Medical Imaging, The Ottawa Hospital, 1053 Carling Ave, Ottawa, Ontario K1Y 4E9, Canada
| | - Carlos H Torres
- Department of Radiology, University of Ottawa, Ottawa, Ontario, Canada; Department of Medical Imaging, The Ottawa Hospital, 1053 Carling Ave, Ottawa, Ontario K1Y 4E9, Canada; Clinical Epidemiology Program/Methods Centre, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - Franco Momoli
- Clinical Epidemiology Program/Methods Centre, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada; Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada
| | - William Petrcich
- Clinical Epidemiology Program/Methods Centre, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - Dar Dowlatshahi
- Clinical Epidemiology Program/Methods Centre, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada; Division of Neurology, Department of Medicine, University of Ottawa, Ottawa, Ontario, Canada
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13
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Nguyen TB, Cron GO, Mercier JF, Foottit C, Torres CH, Chakraborty S, Woulfe J, Jansen GH, Caudrelier JM, Sinclair J, Hogan MJ, Thornhill RE, Cameron IG. Diagnostic accuracy of dynamic contrast-enhanced MR imaging using a phase-derived vascular input function in the preoperative grading of gliomas. AJNR Am J Neuroradiol 2012; 33:1539-45. [PMID: 22442046 DOI: 10.3174/ajnr.a3012] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [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: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE The accuracy of tumor plasma volume and K(trans) estimates obtained with DCE MR imaging may have inaccuracies introduced by a poor estimation of the VIF. In this study, we evaluated the diagnostic accuracy of a novel technique by using a phase-derived VIF and "bookend" T1 measurements in the preoperative grading of patients with suspected gliomas. MATERIALS AND METHODS This prospective study included 46 patients with a new pathologically confirmed diagnosis of glioma. Both magnitude and phase images were acquired during DCE MR imaging for estimates of K(trans)_φ and V(p_)φ (calculated from a phase-derived VIF and bookend T1 measurements) as well as K(trans)_SI and V(p_)SI (calculated from a magnitude-derived VIF without T1 measurements). RESULTS Median K(trans)_φ values were 0.0041 minutes(-1) (95 CI, 0.00062-0.033), 0.031 minutes(-1) (0.011-0.150), and 0.088 minutes(-1) (0.069-0.110) for grade II, III, and IV gliomas, respectively (P ≤ .05 for each). Median V(p_)φ values were 0.64 mL/100 g (0.06-1.40), 0.98 mL/100 g (0.34-2.20), and 2.16 mL/100 g (1.8-3.1) with P = .15 between grade II and III gliomas and P = .015 between grade III and IV gliomas. In differentiating low-grade from high-grade gliomas, AUCs for K(trans)_φ, V(p_φ), K(trans)_SI, and V(p_)SI were 0.87 (0.73-1), 0.84 (0.69-0.98), 0.81 (0.59-1), and 0.84 (0.66-0.91). The differences between the AUCs were not statistically significant. CONCLUSIONS K(trans)_φ and V(p_)φ are parameters that can help in differentiating low-grade from high-grade gliomas.
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Affiliation(s)
- T B Nguyen
- Department of Radiology, The Ottawa Hospital, University of Ottawa, Ottawa, Ontario, Canada.
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Yoshimoto M, Cunha IW, Coudry RA, Fonseca FP, Torres CH, Soares FA, Squire JA. FISH analysis of 107 prostate cancers shows that PTEN genomic deletion is associated with poor clinical outcome. Br J Cancer 2007; 97:678-85. [PMID: 17700571 PMCID: PMC2360375 DOI: 10.1038/sj.bjc.6603924] [Citation(s) in RCA: 218] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
This study examines the clinical impact of PTEN genomic deletions using fluorescence in situ hybridisation (FISH) analysis of 107 prostate cancers, with follow-up information covering a period of up to 10 years. Tissue microarray analysis using interphase FISH indicated that hemizygous PTEN losses were present in 42/107 (39%) of prostatic adenocarcinomas, with a homozygous PTEN deletion observed in 5/107 (5%) tumours. FISH analysis using closely linked probes centromeric and telomeric to the PTEN indicated that subband microdeletions accounted for ∼70% genomic losses. Kaplan–Meier survival analysis of PTEN genomic losses (hemizygous and homozygous deletion vs not deleted) identified subgroups with different prognosis based on their time to biochemical relapse after surgery, and demonstrated significant association between PTEN deletion and an earlier onset of disease recurrence (as determined by prostate-specific antigen levels). Homozygous PTEN deletion was associated with a much earlier onset of biochemical recurrence (P=0.002). Furthermore, PTEN loss at the time of prostatectomy correlated with clinical parameters of more advanced disease, such as extraprostatic extension and seminal vesicle invasion. Collectively, our data indicates that haploinsufficiency or PTEN genomic loss is an indicator of more advanced disease at surgery, and is predictive of a shorter time to biochemical recurrence of disease.
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Affiliation(s)
- M Yoshimoto
- Division of Applied Molecular Oncology, Ontario Cancer Institute, Princess Margaret Hospital, Toronto, Ontario, M5G 2M9, Canada
| | - I W Cunha
- Departamento de Patologia, Centro de Tratamento e Pesquisa, Hospital do Câncer, A.C. Camargo, São Paulo, 01509 010, Brazil
| | - R A Coudry
- Departamento de Patologia, Centro de Tratamento e Pesquisa, Hospital do Câncer, A.C. Camargo, São Paulo, 01509 010, Brazil
| | - F P Fonseca
- Serviço de Urologia, Departamento de Cirurgia Pélvica, Hospital do Câncer, A.C. Camargo, São Paulo, 01509 010, Brazil
| | - C H Torres
- Instituto de Matemática e Estatística, Universidade de São Paulo, São Paulo, 01509 010, Brazil
| | - F A Soares
- Departamento de Patologia, Centro de Tratamento e Pesquisa, Hospital do Câncer, A.C. Camargo, São Paulo, 01509 010, Brazil
| | - J A Squire
- Division of Applied Molecular Oncology, Ontario Cancer Institute, Princess Margaret Hospital, Toronto, Ontario, M5G 2M9, Canada
- Department of Medical Biophysics, Faculty of Medicine, University of Toronto, M5G 2M9, Canada
- Division of Applied Molecular Oncology, Ontario Cancer Institute, Princess Margaret Hospital. 610 University Avenue, Room 9-721, Toronto, Ontario, M5G 2M9, Canada. E-mail:
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Varona ME, Tolosa JE, Cárdenas O, Torres CH, Pardo D, Carrasquilla G, Frumkin H. [Pesticides use by flower companies associated with the Colombian Association of Flower Exporters]. Biomedica 2005; 25:377-89. [PMID: 16276685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
INTRODUCTION In Colombia, pesticide exposure has became a public health problem, as the use of these substances continues to increase. OBJECTIVE The current study accumulated information concerning pesticides used by flower companies in Bogotá and Rionegro (Antioquia) that were associated with Asociación Colombiana de Exportadores de Flores (Asocolflores) in Colombia. MATERIALS AND METHODS Eighty-four companies were stratified by geographic location and size. Company and worker information was collected, and for each company, the process of pesticide application and maintenance of the cultivated flowers was carefully observed. Univariate and bivariate, and correlation analyses were applied for data analysis. RESULTS Sex of workers was 39.4% male and 60.6% female. Pesticides were grouped into 4 toxicity classes: 14.3% were class I, 14.4% class II, 52.0% class III, and 19.2% class IV. Dithiocarbamates was the group of pesticides more commonly used (11.7%). The equipment most frequently used for pesticide application was the "bomba móvil" (92.8%), and the "lanza" (92.9%). Cholinesterase activity measured by the Michel-Aldrige method was the biological marker for exposure to pesticides used in 85.9% of the companies. Recommendations for improvements in their use and for measures to further reduce exposure of workers are made.
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Affiliation(s)
- Marcela E Varona
- Laboratorio de Salud Ambiental, Instituto Nacional de Salud, Bogota, D. C., Colombia.
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