title: Intravoxel incoherent motion MR imaging: comparison of diffusion and perfusion characteristics between nasopharyngeal carcinoma and post-chemoradiation fibrosis.
abstract: OBJECTIVE
  To compare the intravoxel incoherent motion (IVIM) diffusion and perfusion characteristics of nasopharyngeal carcinoma (NPC) and post-chemoradiation fibrosis to aid in their differentiation.
  
  
  METHODS
  Fifty-three (64 %) patients with newly diagnosed NPC and 30 (36 %) patients with biopsy-proven post-chemoradiation fibrosis were recruited into tumour and fibrosis groups respectively. Diffusion-weighted magnetic resonance (MR) imaging was performed using 13 b values (0-1,000 s/mm(2)). Their respective IVIM parameters (D, pure diffusion; f, perfusion fraction; D, pseudodiffusion coefficient) were obtained.
  
  
  RESULTS
  D and f were significantly lower in NPC (D = 0.752 ± 0.194 × 10(-3) mm(2)/s, P <0.001; f = 0.122 ± 0.095, P <0.001) than in fibrosis (D = 1.423 ± 0.364 × 10(-3) mm(2)/s; f = 0.190 ± 0.120); while D was significantly higher in NPC (111.366 ± 65.528 × 10(-3) mm(2)/s, P <0.001) than in fibrosis (77.468 ± 62.168 × 10(-3) mm(2)/s). Respective cut-off values with sensitivity, specificity and accuracy were: D = 1.062 × 10(-3) mm(2)/s (100 %, 100 %, 100 %); f = 0.132 (66.0 %, 100 %, 78.3 %); D = 85.283 × 10(-3) mm(2)/s (100 %, 90.7 %, 96.4 %).
  
  
  CONCLUSIONS
  NPC and post-chemoradiation fibrosis have distinctive IVIM parameters. IVIM MR imaging is potentially useful in discrimination between NPC and fibrosis.
  
  
  CONCLUSIONS
  • New MRI techniques offer greater help in the assessment of nasopharyngeal carcinoma. • Tumour and post-chemoradiation fibrosis have distinctive intravoxel incoherent motion diffusion/perfusion parameters. • Non-invasive IVIM MRI may help differentiate between tumour and fibrosis. • Pure diffusion is a robust independent discriminating factor which improves diagnostic confidence.
authors.affiliation: Department of Diagnostic Radiology, Li Ka Shing Faculty of Medicine, University of Hong Kong, Queen Mary Hospital, Room 406, Block K, Hong Kong, Hong Kong, vincentlai@hkcr.org.
authors.forename: Vincent
authors.initials: V
authors.lastname: Lai
authors.forename: Xiao
authors.initials: X
authors.lastname: Li
authors.forename: Victor Ho Fun
authors.initials: VH
authors.lastname: Lee
authors.forename: Ka On
authors.initials: KO
authors.lastname: Lam
authors.forename: Queenie
authors.initials: Q
authors.lastname: Chan
authors.forename: Pek Lan
authors.initials: PL
authors.lastname: Khong
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002277:Carcinoma; D059248:Chemoradiotherapy / Q000009:adverse effects* / Q000379:methods*; D002648:Child; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009038:Motion; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000473:pathology* / Q000628:therapy*; D017564:Radiation Pneumonitis / Q000209:etiology / Q000473:pathology*; D015203:Reproducibility of Results; D055425:Respiratory-Gated Imaging Techniques / Q000379:methods*; D012680:Sensitivity and Specificity; D016896:Treatment Outcome; D047368:Tumor Burden; D055815:Young Adult