title: Personalized predictive lung dosimetry by technetium-99m macroaggregated albumin SPECT/CT for yttrium-90 radioembolization.
abstract: BACKGROUND
  For yttrium-90 ((90)Y) radioembolization, the common practice of assuming a standard 1,000-g lung mass for predictive dosimetry is fundamentally incongruent with the modern philosophy of personalized medicine. We recently developed a technique of personalized predictive lung dosimetry using technetium-99m ((99m)Tc) macroaggregated albumin (MAA) single photon emission computed tomography with integrated CT (SPECT/CT) of the lung as part of our routine dosimetric protocol for (90)Y radioembolization. Its rationales are the technical superiority of SPECT/CT over planar scintigraphy, ease and convenience of lung auto-segmentation CT densitovolumetry, and dosimetric advantage of patient-specific lung parenchyma masses.
  
  
  METHODS
  This is a retrospective study of our pulmonary clinical outcomes and comparison of lung dosimetric accuracy and precision by (99m)Tc MAA SPECT/CT versus conventional planar methodology. (90)Y resin microspheres (SIR-Spheres) were used for radioembolization. Diagnostic CT densitovolumetry was used as a reference for lung parenchyma mass. Pulmonary outcomes were based on follow-up diagnostic CT chest or X-ray.
  
  
  RESULTS
  Thirty patients were analyzed. The mean lung parenchyma mass of our Southeast Asian cohort was 822 ± 103 g standard deviation (95% confidence interval 785 to 859 g). Patient-specific lung parenchyma mass estimation by CT densitovolumetry on (99m)Tc MAA SPECT/CT is accurate (bias -21.7 g) and moderately precise (95% limits of agreement -194.6 to +151.2 g). Lung mean radiation absorbed doses calculated by (99m)Tc MAA SPECT/CT and planar methodology are both accurate (bias <0.5 Gy), but (99m)Tc MAA SPECT/CT offers better precision over planar methodology (95% limits of agreement -1.76 to +2.40 Gy versus -3.48 to +3.31 Gy, respectively). None developed radiomicrosphere pneumonitis when treated up to a lung mean radiation absorbed dose of 18 Gy at a median follow-up of 4.4 months.
  
  
  CONCLUSIONS
  Personalized predictive lung dosimetry by (99m)Tc MAA SPECT/CT is clinically feasible, safe, and more precise than conventional planar methodology for (90)Y radioembolization radiation planning.
authors.affiliation: Department of Nuclear Medicine and PET, Singapore General Hospital, Outram Road, Singapore 169608, Singapore ; Department of Nuclear Medicine, Austin Hospital, Level 1, Harold Stokes Building, 145 Studley Rd, Melbourne 3084, Victoria, Australia.
authors.forename: Yung Hsiang
authors.initials: YH
authors.lastname: Kao
authors.affiliation: Department of Nuclear Medicine and PET, Singapore General Hospital, Outram Road, Singapore 169608, Singapore.
authors.forename: Butch M
authors.initials: BM
authors.lastname: Magsombol
authors.affiliation: Department of Nuclear Medicine and PET, Singapore General Hospital, Outram Road, Singapore 169608, Singapore.
authors.forename: Ying
authors.initials: Y
authors.lastname: Toh
authors.affiliation: Department of Diagnostic Radiology, Singapore General Hospital, Outram Road, Singapore 169608, Singapore.
authors.forename: Kiang Hiong
authors.initials: KH
authors.lastname: Tay
authors.affiliation: Department of General Surgery, Singapore General Hospital, Outram Road, Singapore 169608, Singapore ; Department of Surgical Oncology, National Cancer Centre Singapore, 11 Hospital Drive, Singapore 169610, Singapore ; Office of Clinical Sciences, Duke-National University of Singapore Graduate Medical School, 8 College Rd, Singapore 169857, Singapore.
authors.forename: Pierce Kh
authors.initials: PKh
authors.lastname: Chow
authors.affiliation: Department of Nuclear Medicine and PET, Singapore General Hospital, Outram Road, Singapore 169608, Singapore.
authors.forename: Anthony Sw
authors.initials: AS
authors.lastname: Goh
authors.affiliation: Department of Nuclear Medicine and PET, Singapore General Hospital, Outram Road, Singapore 169608, Singapore.
authors.forename: David Ce
authors.initials: DC
authors.lastname: Ng
keywords: CT lung densitovolumetry; Lung mass; Partition model; Selective internal radiation therapy; Technetium-99m macroaggregated albumin SPECT/CT; Yttrium-90 radioembolization