title: Assessment of metastatic colorectal cancer with hybrid imaging: comparison of reading performance using different combinations of anatomical and functional imaging techniques in PET/MRI and PET/CT in a short case series.
abstract: OBJECTIVE
  The purpose was to investigate the diagnostic performance of different combinations of anatomical and functional imaging techniques in PET/MRI and PET/CT for the evaluation of metastatic colorectal cancer lesions.
  
  
  METHODS
  Image data of 15 colorectal cancer patients (FDG-PET/CT and subsequent FDG-PET/MRI) were retrospectively evaluated by two readers in five reading sessions: MRI (morphology) alone, MRI/diffusion-weighted MRI (DWI), MRI/PET, MRI/DWI/PET; and PET/CT. Diagnostic performance of lesion detection with each combination was assessed in general and organ-based. The reference standard was given by histology and/or follow-up imaging. Separate analysis of mucinous tumours was performed.
  
  
  RESULTS
  One hundred and eighty lesions (110 malignant) were evaluated (intestine n = 6, liver n = 37, lymph nodes n = 55, lung n = 4, and peritoneal n = 74). The overall lesion-based diagnostic accuracy was 0.46 for MRI, 0.47 for MRI/DWI, 0.57 for MRI/PET, 0.69 for MRI/DWI/PET and 0.66 for PET/CT. In the organ-based assessment, MRI/DWI/PET showed the highest accuracy for liver metastases (0.74), a comparable accuracy to PET/CT in peritoneal lesions (0.55), and in lymph node metastases (0.84). The accuracy in mucinous tumour lesions was limited in all modalities (MRI/DWI/PET = 0.52).
  
  
  CONCLUSIONS
  PET/MRI including DWI is comparable to PET/CT in the evaluation of colorectal cancer metastases, with a markedly higher accuracy when using combined imaging data than the modalities separately. Further improvement is needed in the imaging of peritoneal carcinomatosis and mucinous tumours.
authors.affiliation: Diagnostic and Interventional Radiology, Department of Radiology, Eberhard Karls University, Hoppe-Seyler-Straße 3, 72076, Tuebingen, Germany. cornelia.brendle@med.uni-tuebingen.de.
authors.forename: C
authors.initials: C
authors.lastname: Brendle
authors.affiliation: Diagnostic and Interventional Radiology, Department of Radiology, Eberhard Karls University, Hoppe-Seyler-Straße 3, 72076, Tuebingen, Germany.
authors.forename: N F
authors.initials: NF
authors.lastname: Schwenzer
authors.affiliation: Diagnostic and Interventional Radiology, Department of Radiology, Eberhard Karls University, Hoppe-Seyler-Straße 3, 72076, Tuebingen, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Rempp
authors.affiliation: Diagnostic and Interventional Radiology, Department of Radiology, Eberhard Karls University, Hoppe-Seyler-Straße 3, 72076, Tuebingen, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Schmidt
authors.affiliation: Diagnostic and Interventional Radiology, Department of Radiology, Eberhard Karls University, Hoppe-Seyler-Straße 3, 72076, Tuebingen, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Pfannenberg
authors.affiliation: Nuclear Medicine, Department of Radiology, Eberhard Karls University, Hoppe-Seyler-Straße 3, 72076, Tuebingen, Germany.
authors.forename: C
authors.initials: C
authors.lastname: la Fougère
authors.affiliation: Diagnostic and Interventional Radiology, Department of Radiology, Eberhard Karls University, Hoppe-Seyler-Straße 3, 72076, Tuebingen, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Nikolaou
authors.affiliation: Diagnostic and Interventional Radiology, Department of Radiology, Eberhard Karls University, Hoppe-Seyler-Straße 3, 72076, Tuebingen, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Schraml
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D015179:Colorectal Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D009362:Neoplasm Metastasis; D049268:Positron-Emission Tomography; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D055815:Young Adult
chemical_list: D019788:Fluorodeoxyglucose F18
keywords: Colorectal cancer; Computed tomography imaging; Diffusion-weighted imaging; Magnetic resonance imaging; Positron emission tomography