title: Semi-Quantitative Analysis of Post-Transarterial Radioembolization (90)Y Microsphere Positron Emission Tomography Combined with Computed Tomography (PET/CT) Images in Advanced Liver Malignancy: Comparison With (99m)Tc Macroaggregated Albumin (MAA) Single Photon Emission Computed Tomography (SPECT).
abstract: OBJECTIVE
  The purpose of this study is to evaluate the correlation between pretreatment planning technetium-99m ((99m)Tc) macroaggregated albumin (MAA) SPECT images and posttreatment transarterial radioembolization (TARE) yttirum-90 ((90)Y) PET/CT images by comparing the ratios of tumor-to-normal liver counts.
  
  
  METHODS
  Fifty-two patients with advanced hepatic malignancy who underwent (90)Y microsphere radioembolization from January 2010 to December 2012 were retrospectively reviewed. Patients had undergone (99m)Tc MAA intraarterial injection SPECT for a pretreatment evaluation of microsphere distribution and therapy planning. After the administration of (90)Y microspheres, the patients underwent posttreatment (90)Y PET/CT within 24 h. For semiquantitative analysis, the tumor-to-normal uptake ratios in (90)Y PET/CT (TNR-yp) and (99m)Tc MAA SPECT (TNR-ms) as well as the tumor volumes measured in angiographic CT were obtained and analyzed. The relationship of TNR-yp and TNR-ms was evaluated by Spearman's rank correlation and Wilcoxon's matched pairs test.
  
  
  RESULTS
  In a total of 79 lesions of 52 patients, the distribution of microspheres was well demonstrated in both the SPECT and PET/CT images. A good correlation was observed of between TNR-ms and TNR-yp (rho value = 0.648, p < 0.001). The TNR-yp (median 2.78, interquartile range 2.43) tend to show significantly higher values than TNR-ms (median 2.49, interquartile range of 1.55) (p = 0.012). The TNR-yp showed weak correlation with tumor volume (rho = 0.230, p = 0.041).
  
  
  CONCLUSIONS
  The (99m)Tc MAA SPECT showed a good correlation with (90)Y PET/CT in TNR values, suggesting that (99m)Tc MAA can be used as an adequate pretreatment evaluation method. However, the (99m)Tc MAA SPECT image consistently shows lower TNR values compared to (90)Y PET/CT, which means the possibility of underestimation of tumorous uptake in the partition dosimetry model using (99m)Tc MAA SPECT. Considering that (99m)Tc MAA is the only clinically available surrogate marker for distribution of microsphere, we recommend measurement of tumorous uptake using (90)Y PET/CT should be included routinely in the posttherapeutic evaluation.
authors.affiliation: Departments of Nuclear Medicine, Korea University Anam Hospital, Inchon-ro 73, Seongbuk-gu, Seoul, Korea.
authors.forename: Seunghong
authors.initials: S
authors.lastname: Rhee
authors.affiliation: Departments of Nuclear Medicine, Korea University Anam Hospital, Inchon-ro 73, Seongbuk-gu, Seoul, Korea.
authors.forename: Sungeun
authors.initials: S
authors.lastname: Kim
authors.affiliation: Departments of Nuclear Medicine, Korea University Anam Hospital, Inchon-ro 73, Seongbuk-gu, Seoul, Korea.
authors.forename: Jaehyuk
authors.initials: J
authors.lastname: Cho
authors.affiliation: Departments of Nuclear Medicine, Korea University Anam Hospital, Inchon-ro 73, Seongbuk-gu, Seoul, Korea.
authors.forename: Jukyung
authors.initials: J
authors.lastname: Park
authors.affiliation: Departments of Nuclear Medicine, Korea University Guro Hospital, Seoul, Korea.
authors.forename: Jae Seon
authors.initials: JS
authors.lastname: Eo
authors.affiliation: Departments of Nuclear Medicine, Korea University Guro Hospital, Seoul, Korea.
authors.forename: Soyeon
authors.initials: S
authors.lastname: Park
authors.affiliation: Departments of Nuclear Medicine, Korea University Guro Hospital, Seoul, Korea.
authors.forename: Eunsub
authors.initials: E
authors.lastname: Lee
authors.affiliation: Departments of Radiology, Korea University Anam Hospital, Seoul, Korea.
authors.forename: Yun Hwan
authors.initials: YH
authors.lastname: Kim
authors.affiliation: Departments of Nuclear Medicine, Korea University Anam Hospital, Inchon-ro 73, Seongbuk-gu, Seoul, Korea.
authors.forename: Jae-Gol
authors.initials: JG
authors.lastname: Choe
keywords: Liver malignancy; Microsphere; PET scan; Radioembolization; Single-photon emission computerized tomography; Tc-99m-MAA; Y-90