title: Evaluation of MRI T1-based treatment monitoring during laser-induced thermotherapy of liver metastases for necrotic size prediction.
abstract: OBJECTIVE
  The aim of this study was to evaluate the accuracy of real-time magnetic resonance imaging (MRI) T1-based treatment monitoring for predicting volume of lesions induced by laser-induced thermotherapy (LITT) of liver metastases.
  
  
  METHODS
  This prospective study was approved by the institutional review board and informed consent from all included patients was obtained. In 151 patients, 237 liver metastases were ablated during 372 LITT procedures. 1.5 T MRI treatment monitoring was performed based on longitudinal relaxation time (T1) using fast low-angle shot (FLASH) sequences. Patients underwent additional contrast-enhanced MRI directly after LITT, 24 h after the procedure and during follow-up at 3, 6 and 12 months. The amount of energy necessary to induce a defined necrotic area was investigated within the various liver segments.
  
  
  RESULTS
  The total amount of energy applied during LITT varied from 6.12-225.32 kJ (mean 48.96 kJ). Ablation in liver segments 5 (2.12 kJ/cm(3)) and 8 (2.16 kJ/cm(3)) required the highest energy. The overall pre-ablative metastasis volume ranged from 0.5-51.94 cm(3) (mean 1.99 cm(3), SD 25.49 cm(3)) while the volume measured in the last available T1 image varied from 0.78-120 cm(3) (mean 26.25 cm(3), SD 25.66 cm(3)). Volumes measured via MRI T1-based treatment monitoring showed a stronger correlation with necrosis 24 h after LITT (r = 0.933, p < 0.001) than contrast-enhanced MRI directly after the procedure (r = 0.888, p < 0.001).
  
  
  CONCLUSIONS
  Real-time MRI T1-based treatment monitoring during LITT of liver metastases allows for precise estimation of the resulting lesion volume and improves control of the energy necessary during ablation.
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Frankfurt , Frankfurt , Germany and.
authors.forename: Julian L
authors.initials: JL
authors.lastname: Wichmann
authors.forename: Martin
authors.initials: M
authors.lastname: Beeres
authors.forename: B Maxi
authors.initials: BM
authors.lastname: Borchard
authors.forename: Nagy N N
authors.initials: NN
authors.lastname: Naguib
authors.forename: Boris
authors.initials: B
authors.lastname: Bodelle
authors.forename: Clara
authors.initials: C
authors.lastname: Lee
authors.forename: Stephan
authors.initials: S
authors.lastname: Zangos
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Vogl
authors.forename: Martin G
authors.initials: MG
authors.lastname: Mack
authors.forename: Katrin
authors.initials: K
authors.lastname: Eichler
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D006979:Hyperthermia, Induced; D053685:Laser Therapy; D008113:Liver Neoplasms / Q000473:pathology / Q000556:secondary / Q000628:therapy*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009336:Necrosis / Q000473:pathology / Q000628:therapy*; D009382:Neoplasms, Unknown Primary; D047368:Tumor Burden