title: Diffusion-weighted imaging of malignant ocular masses: initial results and directions for further study.
abstract: OBJECTIVE
  Ocular masses represent a spectrum of malignant tumors and benign lesions that are sometimes difficult to detect and differentiate by conventional imaging techniques. The aim of this study was to characterize a group of malignant ocular masses with DWI, with the goals of establishing reference data and identifying potential clinical applications for improved noninvasive characterization.
  
  
  METHODS
  With institutional review board approval, 26 malignant ocular masses in 22 patients were retrospectively analyzed. Five masses were excluded from further analysis due to nonvisualization. Fifteen retinoblastomas, 5 melanomas, and 1 highly undifferentiated carcinoma were studied. Region-of-interest analysis was performed, and the ADC of each mass was measured and also compared with a normal-appearing thalamus. Lesion thickness was measured, the amount of susceptibility artifact was qualitatively assessed and graded, and the correlation between these factors and retinoblastoma ADC was determined.
  
  
  RESULTS
  Retinoblastomas had an ADC of 0.93 ± 0.3 × 10(-3) mm(2)/s (mean). Melanoma had an ADC of 1.18 ± 0.16 × 10(-3) mm(2)/s. The ADC of retinoblastoma was strongly inversely correlated with lesion thickness, likely representing the effect of partial volume averaging. ADC was not correlated with the amount of subjectively determined susceptibility artifact.
  
  
  CONCLUSIONS
  Malignant ocular tumors were consistently characterized with DWI, though with limitations due to artifact and partial volume averaging. Additional description of DWI of ocular masses and further technical improvements may lead to a clinical role for DWI.
authors: Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095, USA. ali.sepahdari@gmail.com
authors: A R
authors: AR
authors: Sepahdari
authors: R
authors: R
authors: Kapur
authors: V K
authors: VK
authors: Aakalu
authors: J P
authors: JP
authors: Villablanca
authors: M F
authors: MF
authors: Mafee
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D038524:Diffusion Magnetic Resonance Imaging; D005134:Eye Neoplasms / Q000175:diagnosis*; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D009918:Orbital Neoplasms / Q000175:diagnosis*; D012189:Retrospective Studies; D055815:Young Adult