title: Diffusion-weighted MR imaging including bi-exponential fitting for the detection of recurrent or residual tumour after (chemo)radiotherapy for laryngeal and hypopharyngeal cancers.
abstract: OBJECTIVE
  To assess whether diffusion-weighted magnetic resonance imaging (DW-MRI) including bi-exponential fitting helps to detect residual/recurrent tumours after (chemo)radiotherapy of laryngeal and hypopharyngeal carcinoma.
  
  
  METHODS
  Forty-six patients with newly-developed/worsening symptoms after (chemo)radiotherapy for laryngeal/hypopharyngeal cancers were prospectively imaged using conventional MRI and axial DW-MRI. Qualitative (visual assessment) and quantitative analysis (mono-exponentially: total apparent diffusion coefficient [ADC(T)], and bi-exponentially: perfusion fraction [F(P)] and true diffusion coefficient [ADC(D)]) were performed. Diffusion parameters of tumour versus post-therapeutic changes were compared, with final diagnosis based on histopathology and follow-up. Mann-Whitney U test was used for statistical analysis.
  
  
  RESULTS
  Qualitative DW-MRI combined with morphological images allowed the detection of tumour with a sensitivity of 94% and specificity 100%. ADC(T) and ADC(D) values were lower in tumour with values 120 ± 49 × 10(-5) mm(2)/s and 113 ± 50 × 10(-5) mm(2)/s, respectively, compared with post-therapeutic changes with values 182 ± 41 × 10(-5) mm(2)/s (P < 0.0002) and 160 ± 47 × 10(-5) mm(2)/s (P < 0.003), respectively. F(P) values were significantly lower in tumours than in non-tumours (13 ± 9% versus 31 ± 16%, P < 0.0002), with F(P) being the best quantitative parameter for differentiation between post-therapeutic changes and recurrence.
  
  
  CONCLUSIONS
  DW-MRI in combination with conventional MRI substantially improves detection and exclusion of tumour in patients with laryngeal and hypopharyngeal cancers after treatment with (chemo)radiotherapy on both qualitative and quantitative analysis, with F(P) being the best quantitative parameter in this context.
authors.affiliation: Department of Diagnostic, Interventional and Paediatric Radiology, Inselspital, University of Bern, Freiburgstrasse 10, 3010 Bern, Switzerland.
authors.forename: Dechen W
authors.initials: DW
authors.lastname: Tshering Vogel
authors.forename: Peter
authors.initials: P
authors.lastname: Zbaeren
authors.forename: Andreas
authors.initials: A
authors.lastname: Geretschlaeger
authors.forename: Peter
authors.initials: P
authors.lastname: Vermathen
authors.forename: Frederik
authors.initials: F
authors.lastname: De Keyzer
authors.forename: Harriet C
authors.initials: HC
authors.lastname: Thoeny
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001707:Biopsy, Needle; D002294:Carcinoma, Squamous Cell / Q000175:diagnosis* / Q000401:mortality / Q000628:therapy; D059248:Chemoradiotherapy / Q000379:methods; D015331:Cohort Studies; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006258:Head and Neck Neoplasms / Q000175:diagnosis* / Q000401:mortality / Q000628:therapy; D006801:Humans; D007012:Hypopharyngeal Neoplasms / Q000175:diagnosis* / Q000401:mortality / Q000628:therapy; D007150:Immunohistochemistry; D007822:Laryngeal Neoplasms / Q000175:diagnosis / Q000401:mortality / Q000628:therapy; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis* / Q000401:mortality / Q000473:pathology; D018365:Neoplasm, Residual / Q000175:diagnosis* / Q000401:mortality / Q000473:pathology; D011379:Prognosis; D011446:Prospective Studies; D012372:ROC Curve; D018570:Risk Assessment; D000077195:Squamous Cell Carcinoma of Head and Neck; D018709:Statistics, Nonparametric; D015996:Survival Rate