title: [Verification of MR thermometry by means of an in vivo intralesional, fluoroptic temperature measurement for laser-induced thermotherapy ov liver metastases].
abstract: OBJECTIVE
  To evaluate the correlation of MR-measured changes of signal intensity and invasive fluoroptic temperature measurements during MR-guided LITT of liver metastases.
  
  
  METHODS
  In 15 patients with proven liver metastases of colorectal carcinoma, MR-guided LITT was performed with a percutaneous approach in a multiapplicator technique. Two temperature sensitive T1-weighted sequences (FLASH-2D- and TurboFLASH-sequences) were used to map the spatial and temporal distribution of Nd:YAG laser effects. Parallel fluoroptic temperature measurements were carried out by means of an inserted probe in a distance of 5-26 mm (mean: 14 mm) from the laser applicator.
  
  
  RESULTS
  In both sequences a gradually increasing signal loss could be documented during laser application which proved to be reversible after cessation of energy deposition. the percentage of decrease in signal intensity correlated directly with the measured increase of temperature. Invasive fluoroptical evaluation of temperature distribution after 10 min exposure time showed at 5 mm distance from the applicator an increase of temperature of 35 degrees C, in 10 mm distance a mean increase of 9 degrees C +/- 1.7, in 15 mm a mean increase of 7 degrees C +/- 1.6 and in 20 mm a mean increase of 3 degrees C +/- 0.5. This is evidence of thermal tissue damage up to 3 cm in diameter with laser monoapplication. The qualitative evaluation revealed a reproducible correlation of the extent of signal loss around the applicator and the finally induced degree of necrosis.
  
  
  CONCLUSIONS
  Invasive fluoroptical temperature measurements prove the diagnostic reliability of MR thermometry for the online monitoring of LITT of liver metastases.
authors.affiliation: Strahlenklinik und Poliklinik, Virchow-Klinikum der Humboldt-Universität Berlin.
authors.forename: T J
authors.initials: TJ
authors.lastname: Vogl
authors.forename: N
authors.initials: N
authors.lastname: Weinhold
authors.forename: M G
authors.initials: MG
authors.lastname: Mack
authors.forename: P K
authors.initials: PK
authors.lastname: Müller
authors.forename: W R
authors.initials: WR
authors.lastname: Scholz
authors.forename: R
authors.initials: R
authors.lastname: Straub
authors.forename: A
authors.initials: A
authors.lastname: Roggan
authors.forename: R
authors.initials: R
authors.lastname: Felix
mesh_terms: D000328:Adult; D000368:Aged; D001831:Body Temperature; D015179:Colorectal Neoplasms / Q000473:pathology / Q000628:therapy*; D005260:Female; D006801:Humans; D006979:Hyperthermia, Induced / Q000379:methods*; D053685:Laser Therapy; D008113:Liver Neoplasms / Q000473:pathology / Q000556:secondary* / Q000628:therapy*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D015203:Reproducibility of Results