Fusion dual-tracer SPECT-based hepatic dosimetry predicts outcome after radioembolization for a wide range of tumour cell types.
OBJECTIVE
Fusion dual-tracer SPECT imaging enables physiological rather than morphological voxel-based partitioning and dosimetry for (90)Y hepatic radioembolization (RE). We evaluated its prognostic value in a large heterogeneous cohort of patients with extensive hepatic malignancy.


METHODS
A total of 122 patients with primary or secondary liver malignancy (18 different cell types) underwent SPECT imaging after intraarterial injection of (99m)Tc macroaggregated albumin (TcMAA) as a simulation of subsequent (90)Y microsphere distribution, followed by administration of an excess of intravenous (99m)Tc-labelled sulphur colloid (TcSC) as a biomarker for functional liver, and a second SPECT scan. TcMAA distribution was used to estimate (90)Y radiation absorbed dose in tumour (D T) and in functional liver. Laboratory and clinical follow-up were recorded for 12 weeks after RE, and radiographic responses according to (m)RECIST were evaluated at 3 and 6 months. Dose-response relationships were determined for efficacy and toxicity.


RESULTS
Patients were treated with a median of 1.73 GBq activity of resin microspheres (98 patients) or glass microspheres (24 patients), in a whole-liver approach (97 patients) or a lobar approach (25 patients). The objective response rate was 41% at 3 months and 48% at 6 months. Response was correlated with D T (P < 0.01). Median overall survival was 10.1 months (95% confidence interval 7.4 - 12.8 months). Responders lived for 36.0 months compared to 8.7 months for nonresponders (P < 0.01). Stratified for tumour cell type, D T was independently associated with survival (P < 0.01). Absorbed dose in functional liver was correlated with toxicity grade change (P < 0.05) and RE-induced liver disease (P < 0.05).


CONCLUSIONS
Fusion dual-tracer SPECT imaging offers a physiology-based functional imaging tool to predict efficacy and toxicity of RE. This technique can be refined to define dosing thresholds for specific tumour types and treatments, but appears generally predictive even in a heterogeneous cohort.
Division of Interventional Radiology, Stanford University, Stanford, CA, USA, m.lam@umcutrecht.nl.
Marnix G E H
MG
Lam
Arjun
A
Banerjee
Michael L
ML
Goris
Andrei H
AH
Iagaru
Erik S
ES
Mittra
John D
JD
Louie
Daniel Y
DY
Sze
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004621:Embolization, Therapeutic; D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy; D008297:Male; D008863:Microspheres; D008875:Middle Aged; D011829:Radiation Dosage; D019275:Radiopharmaceuticals / Q000008:administration & dosage / Q000627:therapeutic use; D011880:Radiotherapy Planning, Computer-Assisted; D013667:Technetium / Q000008:administration & dosage; D015899:Tomography, Emission-Computed, Single-Photon; D015021:Yttrium Radioisotopes / Q000008:administration & dosage / Q000627:therapeutic use
D019275:Radiopharmaceuticals; D015021:Yttrium Radioisotopes; D013667:Technetium