title: Functional imaging in head and neck squamous cell carcinoma: correlation of PET/CT and diffusion-weighted imaging at 3 Tesla.
abstract: OBJECTIVE
  The purposes of this study were: (a) to prospectively assess the correlation between apparent diffusion coefficient (ADC) values and maximum standardized uptake values (SUVmax) in patients with head and neck squamous cell carcinomas (SCC); and (b) to assess ADC and SUVmax values in relation to different tumour grades and stages in our patient population.
  
  
  METHODS
  The study group comprised 31 consecutive patients with biopsy-proven head and neck squamous cell carcinoma who were examined using a 3T MRI scanner with a 16-channel head and neck coil. In addition to routine sequences, axial (DWIBS) and sagittal (DW-EPI) diffusion-weighted sequences were obtained using b-values of 0 mm(2)/s and 800 mm(2)/s. The ADC maps were calculated automatically. The ADC values of the tumours were measured with three regions of interest (ROIs) of standard size, and an ROI covering the entire tumour. In all patients, contrast-enhanced, whole-body (18)F-FDG PET/CT was performed within 2 weeks of the MRI examination. SUVmax was measured for every tumour using a 3-D freehand ROI that covered the entire tumour. Two-way repeated measures ANOVA was used for group comparisons. The Spearman rank correlation test was performed for ADC values.
  
  
  RESULTS
  Mean ADC values in the 31 SCC were 0.902 (± 0.134) with a ROI of standard size, and 0.928 (± 0.160) with the large ROI measurements on the axial DWIBS sequence. The ADC values of the tumours were significantly higher when measured with the sagittal DW-EPI sequence: 1.051 (± 0.211) and 1.082 (± 0.208). We observed no significant differences in ADC values and SUVmax between the various T stages or histological grades of the tumours. SUVmax values (26.5 ± 12) did not correlate with ADC values on DWIBS or EPI.
  
  
  CONCLUSIONS
  There is no correlation between the FDG uptake and the ADC value in head and neck SCC. The three different tumour grades and four tumour stages present in our study population could not be differentiated based on ADC values or SUV.
authors.affiliation: Department of Radiology, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria. Julia.fruehwald-pallamar@meduniwien.ac.at
authors.forename: Julia
authors.initials: J
authors.lastname: Fruehwald-Pallamar
authors.forename: Christian
authors.initials: C
authors.lastname: Czerny
authors.forename: Marius E
authors.initials: ME
authors.lastname: Mayerhoefer
authors.forename: Benjamin S
authors.initials: BS
authors.lastname: Halpern
authors.forename: Christina
authors.initials: C
authors.lastname: Eder-Czembirek
authors.forename: Markus
authors.initials: M
authors.lastname: Brunner
authors.forename: Matthias
authors.initials: M
authors.lastname: Schuetz
authors.forename: Michael
authors.initials: M
authors.lastname: Weber
authors.forename: Laura
authors.initials: L
authors.lastname: Fruehwald
authors.forename: Andreas M
authors.initials: AM
authors.lastname: Herneth
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D001692:Biological Transport; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging / Q000378:metabolism; D004058:Diffusion; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging / Q000378:metabolism; D049268:Positron-Emission Tomography; D011446:Prospective Studies; D014057:Tomography, X-Ray Computed