title: Collision tumors of the adrenal gland: demonstration and characterization at MR imaging.
abstract: OBJECTIVE
  To evaluate the magnetic resonance (MR) imaging findings in collision tumors of the adrenal gland.
  
  
  METHODS
  MR images obtained in 104 patients with a known primary malignant tumor and an adrenal mass were reviewed to find adrenal glands that contained two contiguous but histologically distinct masses. The findings in such cases were correlated with histopathologic findings.
  
  
  RESULTS
  In two (2%) cases, both MR and histopathologic findings showed a mass within the adrenal gland that consisted of contiguous adrenal adenoma and metastasis, which represented a collision tumor. The adenomatous component in each tumor showed a (quantitative) decrease in signal intensity relative to that of the liver (79% and 61%) on opposed-phase images, whereas the metastatic component showed an increase in signal intensity (50% and 15%). Similarly, the adrenal lesion-to-spleen signal intensity ratio on opposed-phase images was lower for the adenomatous component in each (0.39 and 0.43) than for the metastatic component (1.17 and 0.90).
  
  
  CONCLUSIONS
  MR imaging can demonstrate and enable characterization of the separate components of collision tumors within the adrenal gland. These findings can be crucial in planning and guiding subsequent percutaneous needle biopsy and patient care.
authors.affiliation: Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA.
authors.forename: L H
authors.initials: LH
authors.lastname: Schwartz
authors.forename: M
authors.initials: M
authors.lastname: Macari
authors.forename: A G
authors.initials: AG
authors.lastname: Huvos
authors.forename: D M
authors.initials: DM
authors.lastname: Panicek
mesh_terms: D000236:Adenoma / Q000175:diagnosis*; D000310:Adrenal Gland Neoplasms / Q000175:diagnosis* / Q000556:secondary*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D006801:Humans; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D009378:Neoplasms, Multiple Primary / Q000175:diagnosis*