Post-radioembolization yttrium-90 PET/CT - part 2: dose-response and tumor predictive dosimetry for resin microspheres
1 Department of Nuclear Medicine and PET, Singapore General Hospital, Outram Road, Singapore 169608, Singapore
2 Department of Nuclear Medicine, Sir Charles Gairdner Hospital, Hospital Ave, Perth, Western Australia 6009, Australia
3 Department of Nuclear Medicine, Austin Hospital, Level 1, Harold Stokes Building, 145 Studley Rd, Heidelberg, Melbourne, Victoria 3084, Australia
4 Singapore Bioimaging Consortium, Agency for Science, Technology and Research (A*STAR), 11 Biopolis Way, Helios Building, Singapore 138667, Singapore
5 Agency for Science, Technology and Research (A*STAR) - National University of Singapore, Centre for Life Sciences, National University of Singapore (NUS) Clinical Imaging Research Centre, 14 Medical Drive, Singapore 117599, Singapore
6 Centre for Applied Statistics, University of Western Australia, 35 Stirling Highway, Perth, Western Australia 6009, Australia
7 Department of Research, Sir Charles Gairdner Hospital, Hospital Ave, Perth, Western Australia 6009, Australia
8 Department of Radiation Oncology, National University Cancer Institute Singapore (NCIS), 1E Kent Ridge Road, NUHS Tower Block, Level 7, Singapore 119228, Singapore
9 Department of Diagnostic Radiology, Singapore General Hospital, Outram Road, Singapore 169608, Singapore
10 Department of General Surgery, Singapore General Hospital, Outram Road, Singapore 169608, Singapore
11 Department of Surgical Oncology, National Cancer Centre Singapore, 11 Hospital Drive, Singapore 169610, Singapore
12 Office of Clinical Sciences, Duke-National University of Singapore Graduate Medical School, 8 College Rd, Singapore 169857, Singapore
13 School of Medicine and Pharmacology, University of Western Australia, 35 Stirling Highway, Perth, Western Australia 6009, Australia
14 Department of Radiology, Leiden University Medical Center, Albinusdreef 2, 2300 RC Leiden, The Netherlands
EJNMMI Research 2013, 3:57 doi:10.1186/2191-219X-3-57Published: 25 July 2013
Coincidence imaging of low-abundance yttrium-90 (90Y) internal pair production by positron emission tomography with integrated computed tomography (PET/CT) achieves high-resolution imaging of post-radioembolization microsphere biodistribution. Part 2 analyzes tumor and non-target tissue dose-response by 90Y PET quantification and evaluates the accuracy of tumor 99mTc macroaggregated albumin (MAA) single-photon emission computed tomography with integrated CT (SPECT/CT) predictive dosimetry.
Retrospective dose quantification of 90Y resin microspheres was performed on the same 23-patient data set in part 1. Phantom studies were performed to assure quantitative accuracy of our time-of-flight lutetium-yttrium-oxyorthosilicate system. Dose-responses were analyzed using 90Y dose-volume histograms (DVHs) by PET voxel dosimetry or mean absorbed doses by Medical Internal Radiation Dose macrodosimetry, correlated to follow-up imaging or clinical findings. Intended tumor mean doses by predictive dosimetry were compared to doses by 90Y PET.
Phantom studies demonstrated near-perfect detector linearity and high tumor quantitative accuracy. For hepatocellular carcinomas, complete responses were generally achieved at D70 > 100 Gy (D70, minimum dose to 70% tumor volume), whereas incomplete responses were generally at D70 < 100 Gy; smaller tumors (<80 cm3) achieved D70 > 100 Gy more easily than larger tumors. There was complete response in a cholangiocarcinoma at D70 90 Gy and partial response in an adrenal gastrointestinal stromal tumor metastasis at D70 53 Gy. In two patients, a mean dose of 18 Gy to the stomach was asymptomatic, 49 Gy caused gastritis, 65 Gy caused ulceration, and 53 Gy caused duodenitis. In one patient, a bilateral kidney mean dose of 9 Gy (V20 8%) did not cause clinically relevant nephrotoxicity. Under near-ideal dosimetric conditions, there was excellent correlation between intended tumor mean doses by predictive dosimetry and those by 90Y PET, with a low median relative error of +3.8% (95% confidence interval, -1.2% to +13.2%).
Tumor and non-target tissue absorbed dose quantification by 90Y PET is accurate and yields radiobiologically meaningful dose-response information to guide adjuvant or mitigative action. Tumor 99mTc MAA SPECT/CT predictive dosimetry is feasible. 90Y DVHs may guide future techniques in predictive dosimetry.