Partition Model-Based 99mTc-MAA SPECT/CT Predictive Dosimetry Compared with 90Y TOF PET/CT Posttreatment Dosimetry in Radioembolization of Hepatocellular Carcinoma: A Quantitative Agreement Comparison.
90Y-microsphere selective internal radiation therapy (SIRT) is a valuable treatment in unresectable hepatocellular carcinoma (HCC). Partition-model predictive dosimetry relies on differential tumor-to-nontumor perfusion evaluated on pretreatment99mTc-macroaggregated albumin (MAA) SPECT/CT. The aim of this study was to evaluate agreement between the predictive dosimetry of99mTc-MAA SPECT/CT and posttreatment dosimetry based on90Y time-of-flight (TOF) PET/CT.


METHODS
We compared the99mTc-MAA SPECT/CT results for 27 treatment sessions (25 HCC patients, 41 tumors) with90Y SIRT (7 glass spheres, 20 resin spheres) and the posttreatment90Y TOF PET/CT results. Three-dimensional voxelized dose maps were computed from the99mTc-MAA SPECT/CT and90Y TOF PET/CT data. Mean absorbed dose ([Formula: see text]) was evaluated to compute the predicted-to-actual dose ratio ([Formula: see text]) in tumor volumes (TVs) and nontumor volumes (NTVs) for glass and resin spheres. The Lin concordance ([Formula: see text]) was used to measure accuracy ([Formula: see text]) and precision (ρ).


RESULTS
Administered activity ranged from 0.8 to 1.9 GBq for glass spheres and from 0.6 to 3.4 GBq for resin spheres, and the respective TVs ranged from 2 to 125 mL and from 6 to 1,828 mL. The mean dose [Formula: see text] was 240 Gy for glass and 122 Gy for resin in TVs and 72 Gy for glass and 47 Gy for resin in NTVs. [Formula: see text] was 1.46 ± 0.58 (0.65-2.53) for glass and 1.16 ± 0.41 (0.54-2.54) for resin, and the respective values for [Formula: see text] were 0.88 ± 0.15 (0.56-1.00) and 0.86 ± 0.2 (0.58-1.35). DR variability was substantially lower in NTVs than in TVs. The Lin concordance between [Formula: see text] and [Formula: see text] (resin) was significantly better for tumors larger than 150 mL than for tumors 150 mL or smaller ([Formula: see text] = 0.93 and [Formula: see text] = 0.95 vs. [Formula: see text] = 0.57 and [Formula: see text] = 0.93; P < 0.05).


CONCLUSIONS
In90Y radioembolization of HCC, predictive dosimetry based on99mTc-MAA SPECT/CT provided good estimates of absorbed doses calculated from posttreatment90Y TOF PET/CT for tumor and nontumor tissues. The low variability of [Formula: see text] demonstrates that pretreatment dosimetry is particularly suitable for minimizing radiation-induced hepatotoxicity.
Institute of Radiation Physics, Lausanne University Hospital, Lausanne, Switzerland silvano.gnesin@chuv.ch.
Silvano
S
Gnesin
Institute of Radiation Physics, Lausanne University Hospital, Lausanne, Switzerland.
Laurent
L
Canetti
Nuclear Medicine and Molecular Imaging Department, Lausanne University Hospital, Lausanne, Switzerland; and.
Salim
S
Adib
Institute of Radiation Physics, Lausanne University Hospital, Lausanne, Switzerland.
Nicolas
N
Cherbuin
Nuclear Medicine and Molecular Imaging Department, Lausanne University Hospital, Lausanne, Switzerland; and.
Marina
M
Silva Monteiro
Radiology Department, Lausanne University Hospital, Lausanne, Switzerland.
Pierre
P
Bize
Radiology Department, Lausanne University Hospital, Lausanne, Switzerland.
Alban
A
Denys
Nuclear Medicine and Molecular Imaging Department, Lausanne University Hospital, Lausanne, Switzerland; and.
John O
JO
Prior
Institute of Radiation Physics, Lausanne University Hospital, Lausanne, Switzerland.
Sebastien
S
Baechler
Nuclear Medicine and Molecular Imaging Department, Lausanne University Hospital, Lausanne, Switzerland; and.
Ariane
A
Boubaker
D000328:Adult; D006528:Carcinoma, Hepatocellular / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D000072078:Positron Emission Tomography Computed Tomography / Q000379:methods; D011835:Radiation Protection / Q000379:methods; D011874:Radiometry / Q000379:methods; D011879:Radiotherapy Dosage; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D000072098:Single Photon Emission Computed Tomography Computed Tomography / Q000379:methods; D013668:Technetium Tc 99m Aggregated Albumin; D015021:Yttrium Radioisotopes
D013668:Technetium Tc 99m Aggregated Albumin; D015021:Yttrium Radioisotopes
90Y radioembolization; hepatocellular carcinoma (HCC); predictive dosimetry; selective internal radiation therapy (SIRT)