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@ARTICLE{Almansour:276985,
      author       = {H. Almansour and F. Schick and M. Nachbar and S. Afat and
                      V. Fritz and D. Thorwarth$^*$ and D. Zips$^*$ and F. Bertram
                      and A.-C. Müller and K. Nikolaou and A. E. Othman and D.
                      Wegener},
      title        = {{L}ongitudinal monitoring of {A}pparent {D}iffusion
                      {C}oefficient ({ADC}) in patients with prostate cancer
                      undergoing {MR}-guided radiotherapy on an {MR}-{L}inac at
                      1.5 {T}: a prospective feasibility study.},
      journal      = {Radiology and oncology},
      volume       = {57},
      number       = {2},
      issn         = {1318-2099},
      address      = {Warsaw},
      publisher    = {Sciendo},
      reportid     = {DKFZ-2023-01235},
      pages        = {184 - 190},
      year         = {2023},
      abstract     = {Hybrid MRI linear accelerators (MR-Linac) might enable
                      individualized online adaptation of radiotherapy using
                      quantitative MRI sequences as diffusion-weighted imaging
                      (DWI). The purpose of this study was to investigate the
                      dynamics of lesion apparent diffusion coefficient (ADC) in
                      patients with prostate cancer undergoing MR-guided radiation
                      therapy (MRgRT) on a 1.5T MR-Linac. The ADC values at a
                      diagnostic 3T MRI scanner were used as the reference
                      standard.In this prospective single-center study, patients
                      with biopsy-confirmed prostate cancer who underwent both an
                      MRI exam at a 3T scanner (MRI3T) and an exam at a 1.5T
                      MR-Linac (MRL) at baseline and during radiotherapy were
                      included. Lesion ADC values were measured by a radiologist
                      and a radiation oncologist on the slice with the largest
                      lesion. ADC values were compared before vs. during
                      radiotherapy (during the second week) on both systems via
                      paired t-tests. Furthermore, Pearson correlation coefficient
                      and inter-reader agreement were computed.A total of nine
                      male patients aged 67 ± 6 years [range 60 - 67 years] were
                      included. In seven patients, the cancerous lesion was in the
                      peripheral zone, and in two patients the lesion was in the
                      transition zone. Inter-reader reliability regarding lesion
                      ADC measurement was excellent with an intraclass correlation
                      coefficient of (ICC) > 0.90 both at baseline and during
                      radiotherapy. Thus, the results of the first reader will be
                      reported. In both systems, there was a statistically
                      significant elevation of lesion ADC during radiotherapy
                      (mean MRL-ADC at baseline was 0.97 ± 0.18 × 10-3 mm2/s vs.
                      mean MRL-ADC during radiotherapy 1.38 ± 0.3 × 10-3 mm2/s,
                      yielding a mean lesion ADC elevation of 0.41 ± 0.20 × 10-3
                      mm2/s, p < 0.001). Mean MRI3T-ADC at baseline was 0.78 ±
                      0.165 × 10-3 mm2/s vs. mean MRI3T-ADC during radiotherapy
                      0.99 ± 0.175 × 10-3 mm2/s, yielding a mean lesion ADC
                      elevation of 0.21 ± 0.96 × 10-3 mm2/s p < 0.001). The
                      absolute ADC values from MRL were consistently significantly
                      higher than those from MRI3T at baseline and during
                      radiotherapy (p < = 0.001). However, there was a strong
                      positive correlation between MRL-ADC and MRI3T-ADC at
                      baseline (r = 0.798, p = 0.01) and during radiotherapy (r =
                      0.863, p = 0.003).Lesion ADC as measured on MRL increased
                      significantly during radiotherapy and ADC measurements of
                      lesions on both systems showed similar dynamics. This
                      indicates that lesion ADC as measured on the MRL may be used
                      as a biomarker for evaluation of treatment response. In
                      contrast, absolute ADC values as calculated by the algorithm
                      of the manufacturer of the MRL showed systematic deviations
                      from values obtained on a diagnostic 3T MRI system. These
                      preliminary findings are promising but need large-scale
                      validation. Once validated, lesion ADC on MRL might be used
                      for real-time assessment of tumor response in patients with
                      prostate cancer undergoing MR-guided radiation therapy.},
      keywords     = {ADC (Other) / MR-Linac (Other) / MRI (Other) / adaptive
                      radiotherapy (Other) / image guidance (Other) / prostate
                      carcinoma (Other)},
      cin          = {TU01},
      ddc          = {610},
      cid          = {I:(DE-He78)TU01-20160331},
      pnm          = {899 - ohne Topic (POF4-899)},
      pid          = {G:(DE-HGF)POF4-899},
      typ          = {PUB:(DE-HGF)16},
      pubmed       = {pmid:37341194},
      doi          = {10.2478/raon-2023-0020},
      url          = {https://inrepo02.dkfz.de/record/276985},
}