title: Potential and limitations of magnetic resonance imaging for real-time monitoring of interstitial laser phototherapy.
abstract: OBJECTIVE
  Magnetic resonance (MR) imaging has been suggested as a method to monitor interstitial laser phototherapy (ILP) in deep tissues. Unfortunately, a reliable relation between temperature and MR parameters has not yet been demonstrated. In this study, we examined whether such a relation exists and whether MR imaging can measure absolute temperature or temperature changes.
  
  
  METHODS
  We evaluated, in the range of 21 degrees C to 80 degrees C, the temperature dependence of the MR imaging signal and T1 in samples of liver, water, CuSO4, and oil. Spin-echo and fast low-angle shot (FLASH) sequences were used.
  
  
  RESULTS
  The MR imaging signal of liver, CuSO4, and water continuously decreased when the temperature was increased from 21 degrees C to 80 degrees C. By contrast, the MR imaging signal of the oil increased with increasing temperature up to 40-50 degrees C and then decreased at higher temperatures. We observed a reliable linear relation only between T1 and temperature in a range' of 30-60 degrees C for oil and CuSO4.
  
  
  CONCLUSIONS
  MR imaging has the potential to measure thermal variations with an uncertainty of approximately +/- 10 degrees C. However, the use of MR imaging to monitor the real-time thermal effect induced in biologic tissues during laser irradiation requires further investigation before it can be applied clinically.
authors.affiliation: Division of Health Physics, Istituto Nazionale per lo Studio e la Cura del Tumori, Milano, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Pignoli
authors.forename: R
authors.initials: R
authors.lastname: Marchesini
authors.forename: L
authors.initials: L
authors.lastname: Curti
authors.forename: A E
authors.initials: AE
authors.lastname: Sichirollo
authors.forename: S
authors.initials: S
authors.lastname: Tomatis
authors.forename: R
authors.initials: R
authors.lastname: Musumeci
mesh_terms: D000818:Animals; D002417:Cattle; D019327:Copper Sulfate; D066298:In Vitro Techniques; D053685:Laser Therapy; D008099:Liver; D008279:Magnetic Resonance Imaging; D008991:Monitoring, Physiologic; D009821:Oils; D010789:Phototherapy; D013696:Temperature; D014867:Water
chemical_list: D009821:Oils; D014867:Water; D019327:Copper Sulfate