title: Radiation segmentectomy: a novel approach to increase safety and efficacy of radioembolization.
abstract: OBJECTIVE
  To describe a technique of segmental radioembolization for the treatment of patients with unresectable hepatocellular carcinoma (HCC). Radiation segmentectomy was defined as radioembolization of two or fewer hepatic segments. We sought to (1) calculate dose when activity is delivered segmentally assuming uniform and nonuniform distribution and, (2) determine safety and efficacy of this novel technique.
  
  
  METHODS
  A total of 84 patients with HCC who were treated with (90)Y radioembolization using a segmental approach were included in this analysis. The dose delivered to the segment was calculated assuming uniform and nonuniform microsphere distribution within the treatment volume. To calculate dose assuming nonuniform distribution, a tumor hypervascularity ratio was assigned. Posttreatment response (using size and necrosis guidelines), toxicity, time to progression, and survival were determined.
  
  
  RESULTS
  The median treatment volume was 110 cm(3). The median radiation-naïve liver volume was 1403 cm(3). The median dose delivered to the segment(s) assuming uniform distribution was 521 Gy. Taking into account tumor hypervascularity (nonuniform distribution), the median dose delivered to the tumor and normal infused hepatic volume was 1214 Gy and 210 Gy, respectively. Response by size and necrosis guidelines was seen in 59% and 81% of patients. Grade 3/4 biochemical toxicities were observed in 8 patients (9%). Median time to progression was 13.6 months (95% confidence interval, 9.3-18.7 months); median survival was 26.9 months (95% confidence interval, 20.5-30.2 months).
  
  
  CONCLUSIONS
  Radiation segmentectomy is a safe and efficacious method of selectively delivering high dose to the tumor with minimal exposure of normal parenchyma.
authors.affiliation: Department of Radiology, Northwestern University, Chicago, IL 60611, USA. r-salem@northwestern.edu
authors.forename: Ahsun
authors.initials: A
authors.lastname: Riaz
authors.forename: Vanessa L
authors.initials: VL
authors.lastname: Gates
authors.forename: Bassel
authors.initials: B
authors.lastname: Atassi
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Lewandowski
authors.forename: Mary F
authors.initials: MF
authors.lastname: Mulcahy
authors.forename: Robert K
authors.initials: RK
authors.lastname: Ryu
authors.forename: Kent T
authors.initials: KT
authors.lastname: Sato
authors.forename: Talia
authors.initials: T
authors.lastname: Baker
authors.forename: Laura
authors.initials: L
authors.lastname: Kulik
authors.forename: Ramona
authors.initials: R
authors.lastname: Gupta
authors.forename: Michael
authors.initials: M
authors.lastname: Abecassis
authors.forename: Al B
authors.initials: AB
authors.lastname: Benson
authors.forename: Reed
authors.initials: R
authors.lastname: Omary
authors.forename: Laura
authors.initials: L
authors.lastname: Millender
authors.forename: Andrew
authors.initials: A
authors.lastname: Kennedy
authors.forename: Riad
authors.initials: R
authors.lastname: Salem
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D006528:Carcinoma, Hepatocellular / Q000098:blood supply / Q000000981:diagnostic imaging / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D016001:Confidence Intervals; D004621:Embolization, Therapeutic / Q000009:adverse effects / Q000379:methods*; D005260:Female; D017408:Guidelines as Topic; D006499:Hepatic Artery; D006801:Humans; D008099:Liver / Q000473:pathology / Q000528:radiation effects; D008113:Liver Neoplasms / Q000098:blood supply / Q000000981:diagnostic imaging / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D008297:Male; D008863:Microspheres; D008875:Middle Aged; D009336:Necrosis / Q000473:pathology; D011832:Radiation Injuries / Q000517:prevention & control; D011859:Radiography; D011879:Radiotherapy Dosage; D016019:Survival Analysis; D047368:Tumor Burden; D015021:Yttrium Radioisotopes / Q000009:adverse effects / Q000627:therapeutic use*
chemical_list: D015021:Yttrium Radioisotopes