Prof. Orasa Chawalparit, M.D.

Division : Diagnostic Radiology, Department of Radiology

Specialty groups : Neuro Imaging

Languages : Thai, English

Field of interests : Aging Brain, Advanced MRI, Neuro-oncology, Neurovascular imaging

Thai Board of Neuroimaging
M.Sc. (Clinical Epidemiology)
Thai Board of Family Medicine
Thai Board of General Radiology (Faculty of Medicine Siriraj Hospital, Mahidol University)
MD (Faculty of Medicine Ramathibordee Hospital, Mahidol University)
Research Fellowship in MRI (MGH, Boston, USA)
Professional memberships
Royal College of Radiologist in Thailand
Recent publications
  1. Thientunyakit, T., Sethanandha, C., Muangpaisan, W. et al. Relationships between amyloid levels, glucose metabolism, morphologic changes in the brain and clinical status of patients with Alzheimer’s disease. Ann Nucl Med 34, 337–348 (2020).
  2. Piyapittayanan S, Cheunsuchon P, Chawalparit O. Imaging of central nervous system lymphoma spectrum disorders: review article. J Med Assoc Thai 2019;102(10):1140-8.
  3. K Tantiwetchayanon1, Y Vichianin1, T Ekjeen1, K Srungboonmee2, C Ngamsombat3, O Chawalparit3, and Alzheimer’s Disease Neuroimaging Initiative*.Comparison of the WEKA and SVM-light based on support vector machine in classifying Alzheimer’s disease using structural features from brain MR imaging. IOP Conf. Series: Journal of Physics: Conf. Series 1248 (2019) 012003
  4. Piyapittayanan S, Jarunnarumol N, Laohaprasitiporn P, Noiwatana S, Chawalparit O. Diagnostic Performance of Short MR-Neurography Protocol for Brachial Plexus Injuries. SMJ 2019;71(4): JULY-AUGUST:284-9.
  5. Ngamsombat C, Dechasasawat T, Wongsripuemtet J, Charnchaowanish P, Muangpaisan W, Chawalparit O. The evaluation of posterior cingulate gyrus by diffusion tensor imaging in Alzheimer’s disease patients compared with normal control subjects. Siriraj Medical Journal 2019;71(2):117-122.
  6. Chawalparit O, Wontaneeporn N, Muangpaisan W, Thientunyakit T, Charnchaowanish P, Ngamsombat C. MRI Hippocampal subfield volume analysis: Comparison between Alzheimer’s disease, mild cognitive impairment, and normal aging subjects in an amyloid PET project. J Alzheimers Dis Parkinsonism 9:459. doi:10.4172/2161-0460.1000459 January 2019
  7. Vichianin Y, Kareesaw A, Chawalparit O. Optimizing fractional intensity threshold for FSL-brain extraction tool (BET) and comparing with FreeSurfer on 3D T1W MR images. Siriraj Medical Journal 2018;70(5):391-396.
  8. Chawalparit O, Ngamsombat C, Aurboonyawat T, Zhang S. Intracranial Black-Blood Vessel Wall Magnetic Resonance Imaging: Initial Clinical Experience in a Single-Center Study. Siriraj Medical Journal 2018;70(4):327-34.
  9. Tritrakarn S, Jitprapaikulsan J, Thakolwiboon S, Piyapittayanan S, Ngamsombat C, Chawalparit O, Prayoonwiwat N. Evaluation of the NMOSD 2015 imaging guideline to differentiate between diagnosis of multiple sclerosis and neuromyelitis optica spectrum disorder in Thai patients. Neurology Asia 2018; 23(1):61–8.
  10. Thientunyakit T, Sethanadha C, Muangpaisan W, Chawalparit O, Arunrung K, Siriprapa T, et al. Implementation of [18F]-labeled amyloid brain PET imaging biomarker in the diagnosis of Alzheimer’s disease:first-hand experience in Thailand. Nuclear Medicine Communications2018;39(2):186-192.
  11. Piyapittayanan S, Segsarnviriya C, Ngamsombat C, Witthiwej T, Cheunsuchon P, Charnchaowanish P, Chawalparit O. Comparison between dynamic contrast-enhanced MRI and dynamic susceptibility contrast MRI in glioma grading. Siriraj Medical Journal 2017;69:369-76.
  12. Ngamsombat C, Zhang Z, Guo H, Lerdthusnee K, Witthiwej T, Muangpaisan W, et al. Comparison of Microfiber Alteration of corticospinal tract in Idiopathic Normal Pressure Hydrocephalus Patients and Normal control subject by Diffusion Tensor Imvichiaaging. J Med Assoc Thai 2017; 100(suppl.4):s41-s48.
  13. Witthiwej T, et al. MRI study of morphologic features and CSF hydrodynamics to predict ventriculoperitoneal shunt responsiveness in normal pressure hydrocephalus. J Med Assoc Thai 2017; 100(suppl.4):s32-s40.
  14. Witthiwej T, Thongnual K, Wongprapairoj S, Chawalparit O, Piyapittayanan S, Sangruji T. Correlation between magnetic resonance spectroscopy and perfusion at non-enhancing edematous area and tumor recurrence in high-grade gliomas after maximal safe resection. J Med Assoc Thai 2017;100(Suppl.3):S79-S90.
  15. Wongyingsinn M, Tantigate D, Witthiwej T, Chawalparit O. Cerebral fat embolism syndrome following urgent debridement and application of skeletal traction for the right femur: A case report. J Med Assoc Thai 2017; 100 (Suppl. 2): S170-5.
  16. Ngamsombat C, Wongsawaeng D, Thuangtong A, Phasukkijwatana N, Prakhunhungsit S, Witthiwej T, Sitthinamsuwan B, Charnchaowanish P, Weankhanan J, Chawalparit O. Preoperative Diffusion Tensor Imaging Analysis of Optic Radiations: Study in Pituitary Macroadenoma Patients with Optic Chiasm Compression. J Med Assoc Thai 2017; 100 (Suppl. 2): S76-S81
  17. Wongsripuemtet J, Wongfukiat O, Vichianin Y, Ngamsombat C, Witthiwej T, Sitthinamsuwan B, Aurboonyawat T, Chankaew E, Chawalparit O. Feasibility study of language lateralization using Thai version of language paradigm for functional MRI in clinical service. J Med Assoc Thai 2016; 99 (12): 1344-54.
  18. Charnchaowanish P, Chawalparit O. Comparison of high resolution T2W and Gd-T1W of MRI internal acoustic canal in sensorineural hearing loss. J Med Assoc Thai 2016; 99 (11): 1245-9
  19. Ngamsombat C, Wongsripuemtet J, Manochiopinig S, Piyapittayanan S, Chaovongphanit S, Chawalparit O. The Arcuate Fasciculus: Analysis of white matter connection in Thai language system using diffusion tensor imaging and feasibility in lateralization of the dominant hemisphere. Siriraj Med J 2015;67:205-12.
  20. Chawalparit O, Manochiopinig S, Vichianin Y, Wongsripuemtet J, Siwasattayanon P, Ngamsombat C, Chavalparit P, Charnchaowanish P, Pornpunyawuth P, Chaovongphanit S, Wongsawat Y, Ruangvaravate N. Siriraj Thai language paradigm for functional MRI: A pilot study in normal volunteers. Siriraj Med J 2015;67:181-186.
  21. Namyong, J, Aurboonyawat T , Chankaew, E, Chawalparit O, Tritrakarn S, Srirabheebhat P, Wongbhanuwich V, Songsaeng D, Boonma J. Computerized tomographic angiography for detection of cerebral vasospasm after ruptured intracranial aneurysm. J Med Assoc Thai 2015: 98; 804-11.
  22. Pitaknitinan N, Veerasarn V, Chawalparit O. MRI predictors of survival in patients with glioblastomas. Siriraj Med J 2015;67:46-52.
  23. Tanboon J, Aurboonyawat T, Chawalparit O. A 29-year-old man with progressive short term memory loss. Brain Pathology 24 (2014) 103–106.
  24. Chawalparit O, Sangruchi T, Witthiwej T, Sathornsumetee S, Tritrakarn S, Piyapittayanan S, Chaicharoen P, Direksunthorn T, Charnchaowanish P. Diagnostic performance of advanced MRI in differentiating high-grade from low-grade gliomas in a setting of routine service. J Med Assoc Thai 2013; 96 (10): 1365-73.
  25. Direksunthorn T, Chawalparit O, Sangruchi T, Witthiwej T, Tritrakarn S, Piyapittayanan S, Charnchaowanish P, Pornpunyawut P, Sathornsumetee S. Diagnostic performance of perfusion MRI in differentiating low-grade and high-grade gliomas: advanced MRI in glioma, a Siriraj project. J Med Assoc Thai 2013; 96 (9): 1183-90
  26. Piyapittayanan S, Chawalparit O, Tritakarn S, Witthiwej T, Sangruchi T, Nunta-aree S, Sathornsumetee S, Itthimethin P, Komoltri C. Value of diffusion tensor imaging in differentiating high-grade from low-grade gliomas. J Med Assoc Thai 2013; 96 (6):716-21.
  27. Prayoonwiwat N, Chawalparit O, Pienpuck W, Ngamsombat C, Wongsripuemtet J, Siritho S. MRI features and anti-AQP4 antibody status in Idiopathic inflammatory demyelinating CNS disease (IIDCD) in Thai patients. Neurology Asia 2013; 18(1) : 73 – 81.
  28. Chawalparit O, Chareewit. Ischemic Cerebrovascular Disease and Calcified Intracranial Vertebrobasilar Artery: A Case-Control Study by Using Cranial CT. J Med Assoc Thai 2013; 96 (3):346-50.
  29. Witthiwej T, Sathira-ankul P, Chawalparit O, Chotinaiwattarakul W, Tisavipat N, Charnchaowanish P. MRI study of intracranial hydrodynamics and ventriculoperitoneal shunt responsiveness in patient with normal pressure hydrocephalus. J Med Assoc Thai 2012;95:1556-1562.
  30. Jitpratoom P, Siritho S, Chawalparit O, Prayoonwiwat N. Brain and spinal cord magnetic resonance imaging in Thai multiple sclerosis patients. Neurology Asia 2012; 17(1) : 55 – 61
  31. Vongvaivanich K, Chawalparit O. Laughing headache. The Bangkok Medical Journal 2012;3:53-5.
  32. Wonglaksanapimon S, Chawalparit O, Khumpunnip S, Tritrakarn S, Chiewvit P, Charnchaowanish P. Vertebral body compression fracture: discriminating benign from malignant causes by diffusion-weighted MR imaging and apparent diffusion coefficient value. J Med Assoc Thai 2012; 95 (1): 81-7.
  33. Chawalparit O, Tisavipat N. Recent advances in neuroimaging. The Bangkok Medical Journal;2011:85-91.
  34. Chawalparit O, Tritrakarn S, Charnchaowanish P. Pornpunyawut P, S. Chobaroom. Clinical application of susceptibility weighted image: exploring from routine practice. The Neuroradiology Journal 2011;1: 107-116
  35. Chawalparit O, Wattanasen Y, Sangruchi T. Predictive value of MRI and CT findings in childhood medulloblastoma studied in Thai patients. Siriraj Med J 2010;62:112-5.
  36. Chawalparit O, Siriacharwattana W. Evidence of vascular compromise over the visual cortex during migrainous headache: A case report with MRI study. J Med Assoc Thai 2010;93(6):749-52.
  37. Senanarong, V; Wannasaeng, S; Poungvarin, N; Jamjumras, P; Chawalparit, O; Raksasit, A; Udompanthurak, S; Cummings, J. Difference between amnestic and non-amnestic mild cognitive impairment: a community study in Thai elderly. Eur J Neurol 2009; 16: 340-340.
  38. Pisarnpong A, Boonma P, Sukumalchantra S, Nuntaaree S, Chawalparit O, Sachthep S. A case report of a 42-year-old Thai woman with multiple brain abcesses caused by Listeria monocytogenes. J of the Neurological Sciences. 2009; 285 S186-S186 .
  39. Chawalparit O, Artkaew C, Anekthananon T, Tisavipat N, Charnchaowanish P, Sangruchi T. Diagnostic accuracy of perfusion CT in differentiating brain abscess from necrotic tumor. J Med Assoc Thai 2009;92:531-6.
  40. Chawalparit O ,Wonglaksanapimon S, Songsaeng D, Saenanarong V. Reliability Study of White Matter Rating Scale for the Dementia and Disability in Thai Elderly Project. . J Med Assoc Thai 2009;92:537-42.
  41. Chong HT, Ramli N, Lee KH, Kim BJ, Ursekar M, Dayananda BS, et al.Magnetic resonance imaging of Asians with multiple sclerosis was similar to that of the West. Can J Neurol.Sci 2006;33:95-100.
  42. Chawalparit O, Saenanarong V, Chiewvit P. CT criteria in vascular dementia: a study in Thai population. Siriraj Med J 2006;58:643-7.
  43. Charoensak A, Chawalparit O, Suttinont C, Niwattayakul K, Losuwanaluk K, Saowaluk S, et al. Scrub typhus: Chest radiographic and clinical findings in 130 Thai patients. J Med Assoc Thai 2006;89:600-7.
  44. Chawalparit O, Churojana A, Chiewvit P, Thanapipatsri S, Vamvanij V, Charnchaowanish P. The limited protocol MRI in diagnosis of lumbar disc herniation. J Med Assoc Thai 2006;89(2):182-9.
  45. Chawalparit O, Charoengsak A, Chierakul N. HRCT of pulmonary tuberculosis mimicks malignancy: a preliminary report. J Med Assoc Thai 2006;89(2): 190-195.
  46. Chawalparit O, Prayoonwiwat N. MRI of Multiple sclerosis in Thai patients. J Med Assoc Thai 2006;89(3):422-7.
  47. Suthikeeree W, Chawalparit O, Tongdee T. Spiral CT in the diagnosis of pulmonary embolism. Siriraj Med J 2005;57(12):526-30.
  48. Charnchaowanish P, Thamnumsuk K, Chawalparit O, Noivatana S, Saiviroonporn P. Magnetic resonance spectroscopy in gliomatosis cerebri patients.Thai J Radiological Technol 2004;29(3): 61-6.
  49. Charnchaowanish P, Chawalparit O. 3D-TOF for screening the patients with clinical symptom of dural sinus thrombosis. Thai J Radiological Technol 2004;29(2): 23-6.
  50. Charnchaowanish P, Chawalparit O, Tisavipat N, Suthipongchai S. Reliability study in quantitative analysis of MRI CSF flow study. Thai J Radiological Technol 2004;29(1):1-4.
  51. Chong HT, Ramli N, Lee KH, Kim BJ, Ursekar M, Dayananda BS, et al. Low sensitivity of McDonald MRI criteria in the diagnosis of multiple sclerosis among Asians. Neurology Asia 2004;9:47-53.
  52. Saesue P, Chankaew E, Chawalparit O, Na Ayudhya NS, Muangsomboon S, Sangruchi T. Primary extraskeletal osteosarcoma in the pineal region. Case report. J Neurosurg. 2004 Dec;101(6):1061-4.
  53. Chawalparit O, Thanongchai S. Advanced technology in Thoracic Imaging จดหมายข่าวสมาคมอุรเวชช์ฯ 2546;12(1):3-5.
  54. Suthipongchai S, Chawalparit O, Churojana A, Poungwarin N. Vascular loop compressing Facial nerve in hemifacial spasm:demonstrated by 3D-PCMRA in 101 patients.J Med Assoc Thai 2004;87:219-24.
  55. Pongpornsup S, Chawalparit O, Pacharn P. Imaging findings and prevalence of central precocious puberty at Siriraj Hospital. Siriraj Hosp Gaz 2003;55(12):713-20.
  56. Chawalparit O. Imaging evaluation in cerebral sinovenous thrombosis. The Neurology Journal of Thailand 2003;3(2):104-116.
  57. Arayawichanont A, Senanarong V, Chawalparit O, Sangruchi T, Poungvarin N. Stroke in the young with left ventricular mass : a report of two rare cases and a review of the literature.Intern Med J Thai 2003;19(1):41-7.
  58. Chierakul N, Dejsomritrutai W, Chawalparit O, Tongdee T, Sombutboon M, Jaichuen S. The prevalence of tuberculosis among nurses of Siriraj Hospital. Thai J Tuberc Chest Dis 2002;23:73-7.
  59. Chawalparit O, Churojana A, Sil-u-dom S, Saiviroonporn P, Julavisetkul R, Prayoonwiwat N, Poungvarin N. The accuracy of magnetic resonance venography for diagnosis of dural sinus thrombosis. Siriraj Hosp Gaz 2002;54(4):231-4.
  60. Chiewvit P., Janyavanich V., Soonthonpong N., Churoj A., Chawalparit O., Suthipongchai S. Moyamoya syndrome: Post cranial irradiation of pineal gland tumor. Interventional Neuroradiology. 2001. 7 (2): 167-174.
  61. Noiwatana S, Tosakul A, U-wattanasombut W, Chawalparit O, Churojana A, Suthipongchai S. Comparison axial image of facial nerve and vascular architecture at the brain stem between 3D PC parallel to infraorbital line and 3D PC 27 degree angulate to infraorbitomeatal line. Bulletin Dept Med Serv 2001;26(12):547-52.
  62. Chawalparit O, Moungsomboon S, Sangruchi. Radiopathological conference of Siriraj Hospital : Pleomorphic xanthoastrocytomas:a rare brain tumor. Siriraj Hosp Gaz 2000;52:828-31.
  63. Muansomboon K, Limanond P, Chawalparit O, et al. Nocardial brain abscess. Siriraj Hosp Gaz 2000;52:411-6.
  64. Limanond P, Chawalparit O, Tongdee T, et al. The crazy paving pattern: a nonspecific sign on HRCT chest. Asean J of Radiology 2000;6:179-184.
  65. Chawalparit O, Suchato N, Churojana A, et al. Absent septum pellucidum: is it importance? Asean J of Radiology 2000;6:121-30.
  66. Churojana A, Suchato N,Chiewvit P, Chawalparit O, Suthipongchai S. Endovascular treatment of arteriovenous malformations in Siriraj Hospital. Siriraj Hosp Gaz 2000;52:37-52.
  67. Arayawichanont A, Chawalparit O, Sangruchi T, Saenanarong V. Granulomatous amoebic encephalitis:report of two cases with neuroimaging findings. Asean J of Radiology 2000;6:83-9.
  68. Thoongsuwan N, Churojana A, Chawalparit O, Suthipongchai S. CT and MRI finding in human spaganosis. Asean J of Radiology 1999;5:281-4.
  69. Chawalparit O, Suthipongchai S. Kallmann syndrome:a case report of MRI findings. Asean J of Radiology 1999;5:285-7.
  70. Chawalparit O, Uoowatanasombut W, Jitbanchuen S, Charnchaowanish P, Tosakul A, Suthipongchai S, Jitnuson P. Pituitary bright spot:incidence in routine brain MRI studying in Thai people. Asean J of Radiology 1998;4:27-9.
  71. Suthipongchai S, Chawalparit O, Chiewvit P, Churojana A. Endovascular treatment of traumatic aneurysm involving head and neck region. Handbbok in 9th Congress Asean Asso. Of Radiology 24th Jan 1997 Singapore.
  72. Suthipongchai S, Ponpech S, Sirivimonmas S, Chawalparit O, Churojana A, Chiewvit P. Interventional neuroradiology in Thailand 1989-1997. Interventional Neuroradiology 1997;3:185-98.
  73. Chawalparit O, Danpukdee K, Suthipongchai S, Chiewvit P. MR imaging of brain in Wilson’s disease. Asean J of Radiology 1997;3:37-41.
  74. Punnotok P, Chawalparit O, Suthipongchai S. Cervical cord lipoma: a case report of MRI finding. Siriraj Hosp Gaz 1995;47:428-31.
  75. Vanapruks S, Prabhasawat K, Chawalparit O, Chaichan P. Imaging of atherosclerosis. Intern Med 1994;10:93-6.
  76. Chawalparit O, Jitnuson P. MRI of the mediastinal lymphoma. Siriraj Hosp Gaz.1994;46:795-7.
  77. Leelasitorn V, Chawalparit O, Chiewvit P, Jitnuson P. Useful of CT in differentiation of pleural lesion from pulmonary lesion. Siriraj Hosp Gaz.1992;44:42-4.
  78. Chawalparit O, Phupat V, Roonmaitre C, Jitnuson P. Third cranial nerve palsy from suprasellar meningioma. Siriraj Hosp Gaz.1991;43:557-60.
  79. Chawalparit O, Jitnuson P. Computed tomography of thymoma. Siriraj Hosp Gaz.1991;43:402-3.
  80. Lumyornsatein B, Chawalparit O. Thoracocentesis loculated empyema using gray scale ultrasonis guidance. Thai J of Radiology 1991;28:75-9.
  81. Chawalparit O, Jitnuson P. Radiological appearances of alveolar proteinosis: a case report. Thai J of Radiology 1991;28:27-31.
  82. Chawalparit O, Jitnuson P, Chaikuna J, Pussapakom R. Ultrasonography of pulmonary and pleural lesion. Siriraj Hosp Gaz.1991;43(1):18-24.
  83. Chawalparit O, Leelasitorn V, Vanapruks S, Valsorn N. Embolization of rupture internal mammillary artery in blunt chest injury:a case report. Thai J of Radiology 1989;26:47-51.
  84. Chawalparit O, Rattanamart V, Preehajinda R. Radionuclide esophageal transit. Thai J of Radiology 1989;26(3):91-6.


  1. Textbook of Radiology for Medical student
  2. Imaging in critical care
  3. Ultrasound in clinical practice
  4. Clinical MRI in common CNS disease 2008, 2017
  5. Atlas of Pediatric neuroimaging Part I…common congenital disease 2010
  6. Oncologic imaging 2009