title: Can C-arm cone-beam CT detect a micro-embolic effect after TheraSphere radioembolization of neuroendocrine and carcinoid liver metastasis?
abstract: OBJECTIVE
  Radioembolization with yttrium-90 microspheres is a therapy that is used for hepatic tumors. 20-30 μm microspheres loaded with Y90 are supposedly occluding tumor vessels at the capillary level. Then, these spheres deliver high-dose radiation to the tumor. However, this theoretical embolic effect has never been appreciated in imaging. Dual-Phase cone-beam computed tomography (DPCBCT) is a multi-phasic intra-procedural scan that uses only one contrast media injection to visualize early (feeding vessel) and delayed (capillary level) tumor enhancement. The purpose of this study was to determine whether there is a micro-embolic effect induced by TheraSpheres® (MDS Nordion, Ottawa, Ontario, Canada) at the capillary level by using DPCBCT imaging.
  
  
  METHODS
  14 patients with 72 carcinoid or neuroendocrine tumors were treated with radioembolization, and all underwent DPCBCT (Allura Xper, Philips Healthcare) imaging before and immediately after radioembolization with TheraSpheres®. Tumor enhancement was measured in each phase by drawing a region of interest within the tumors.
  
  
  RESULTS
  72 tumors were evaluated: average tumor density in the early arterial phase was 241 and 230 Hounsfield units (HU) (p<0.001) before and after radioembolization, respectively; the average density in the delayed arterial phase was 226 and 161 HU (p<0.001) before and after radioembolization, respectively. Average difference in tumor attenuation before and after radioembolization in early arterial and delayed phase was 11 HU and 64 HU (p<0.001), respectively.
  
  
  CONCLUSIONS
  The significant decrease in tumor enhancement in the DPCBCT delayed phase after TheraSpheres® injection indicates that there is an appreciable microembolic effect at the tumor capillary bed level.
authors.affiliation: Division of Vascular and Interventional Radiology, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Hospital, Baltimore, Maryland 21287, USA.
authors.forename: Olivier
authors.initials: O
authors.lastname: Pellerin
authors.forename: MingDe
authors.initials: M
authors.lastname: Lin
authors.forename: Nikhil
authors.initials: N
authors.lastname: Bhagat
authors.forename: Wenbo
authors.initials: W
authors.lastname: Shao
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Geschwind
mesh_terms: D000368:Aged; D002276:Carcinoid Tumor / Q000098:blood supply / Q000473:pathology / Q000532:radiotherapy / Q000628:therapy*; D003131:Combined Modality Therapy; D054893:Cone-Beam Computed Tomography / Q000379:methods; D004621:Embolization, Therapeutic / Q000379:methods*; D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000098:blood supply / Q000532:radiotherapy / Q000556:secondary* / Q000628:therapy*; D008297:Male; D008863:Microspheres; D008875:Middle Aged; D018358:Neuroendocrine Tumors / Q000098:blood supply / Q000473:pathology / Q000532:radiotherapy / Q000628:therapy*; D011446:Prospective Studies; D019275:Radiopharmaceuticals / Q000008:administration & dosage*; D014057:Tomography, X-Ray Computed / Q000379:methods; D015021:Yttrium Radioisotopes / Q000008:administration & dosage*
chemical_list: D019275:Radiopharmaceuticals; D015021:Yttrium Radioisotopes