title: Molecular imaging of malignant tumor metabolism: whole-body image fusion of DWI/CT vs. PET/CT.
abstract: OBJECTIVE
  To prospectively investigate the technical feasibility and performance of image fusion for whole-body diffusion-weighted imaging (wbDWI) and computed tomography (CT) to detect metastases using hybrid positron emission tomography/computed tomography (PET/CT) as reference standard.
  
  
  METHODS
  Fifty-two patients (60 ± 14 years; 18 women) with different malignant tumor disease examined by PET/CT for clinical reasons consented to undergo additional wbDWI at 1.5 Tesla. WbDWI was performed using a diffusion-weighted single-shot echo-planar imaging during free breathing. Images at b = 0 s/mm(2) and b = 700 s/mm(2) were acquired and apparent diffusion coefficient (ADC) maps were generated. Image fusion of wbDWI and CT (from PET/CT scan) was performed yielding for wbDWI/CT fused image data. One radiologist rated the success of image fusion and diagnostic image quality. The presence or absence of metastases on wbDWI/CT fused images was evaluated together with the separate wbDWI and CT images by two different, independent radiologists blinded to results from PET/CT. Detection rate and positive predictive values for diagnosing metastases was calculated. PET/CT examinations were used as reference standard.
  
  
  RESULTS
  PET/CT identified 305 malignant lesions in 39 of 52 (75%) patients. WbDWI/CT image fusion was technically successful and yielded diagnostic image quality in 73% and 92% of patients, respectively. Interobserver agreement for the evaluation of wbDWI/CT images was κ = 0.78. WbDWI/CT identified 270 metastases in 43 of 52 (83%) patients. Overall detection rate and positive predictive value of wbDWI/CT was 89% (95% CI, 0.85-0.92) and 94% (95% CI, 0.92-0.97), respectively.
  
  
  CONCLUSIONS
  WbDWI/CT image fusion is technically feasible in a clinical setting and allows the diagnostic assessment of metastatic tumor disease detecting nine of 10 lesions as compared with PET/CT.
authors: Department of Medical Radiology, Institute of Diagnostic and Interventional Radiology, University Hospital, Zurich, Switzerland.
authors: Caecilia S
authors: CS
authors: Reiner
authors: Michael A
authors: MA
authors: Fischer
authors: Thomas
authors: T
authors: Hany
authors: Paul
authors: P
authors: Stolzmann
authors: Daniel
authors: D
authors: Nanz
authors: Olivio F
authors: OF
authors: Donati
authors: Dominik
authors: D
authors: Weishaupt
authors: Gustav K
authors: GK
authors: von Schulthess
authors: Hans
authors: H
authors: Scheffel
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D009369:Neoplasms / Q000175:diagnosis*; D049268:Positron-Emission Tomography / Q000379:methods*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed / Q000379:methods*; D051598:Whole Body Imaging