title: Evaluation of CT and MRI scanning among cancer patients in Ontario.
abstract: BACKGROUND
  Computed tomography (CT) and magnetic resonance imaging (MRI) utilization in Ontario increased drastically since the early 1990s. The effect of an increased number of cancer diagnoses, and an increase in indications for scans has not been assessed. This study was conducted to determine trends in utilization of CT and MRI in cancer patients in Ontario over a period of 9 years.
  
  
  METHODS
  Using Ontario Health Insurance Plan billing data linked to the Ontario Cancer Registry, rates of CT and MRI were analyzed by region, year, scan type and socioeconomic status.
  
  
  RESULTS
  CT in cancer patients increased 2.3-fold and accounted for approximately 24% of these scans. MRI in cancer patients increased by 4.2-fold and accounted for approximately 10% of these scans. Imaging rates for cancer patients increased more gradually than that of the general population. Substantial variation in the rate of both scans by region of patient residence existed. Even greater variation by the location of the scanner was demonstrated, indicating that many cancer patients traveled outside their region for imaging. There was little evidence of variation in scanning rates by socioeconomic status.
  
  
  CONCLUSIONS
  A minority of CT and MRI performed in Ontario are for cancer care. Regional variation in imaging rates suggest that utilization guidelines be developed or knowledge transfer initiatives improve compliance to existing guidelines are needed. A significant number of cancer patients travel outside their region for diagnostic imaging; this should influence decisions about the location of new scanners.
authors: Institute for Clinical Evaluative Sciences, 2075 Bayview Ave., Toronto, Ontario, Canada M4N 3M5. natalie.coburn@sunnybrook.ca
authors: Natalie
authors: N
authors: Coburn
authors: Raymond
authors: R
authors: Przybysz
authors: Lisa
authors: L
authors: Barbera
authors: David C
authors: DC
authors: Hodgson
authors: Andreas
authors: A
authors: Laupacis
authors: Calvin
authors: C
authors: Law
mesh_terms: D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000706:statistics & numerical data*; D008297:Male; D009369:Neoplasms / Q000453:epidemiology*; D009864:Ontario / Q000453:epidemiology; D012042:Registries; D012959:Socioeconomic Factors; D014057:Tomography, X-Ray Computed / Q000706:statistics & numerical data*