Image-Guided Personalized Predictive Dosimetry by Artery-Specific SPECT/CT Partition Modeling for Safe and Effective ⁹⁰Y Radioembolization

Example of sublesional dosimetry with left radioembolization lobectomy intent. Patient 2 had recurrent HCC at segment IV resection margin. Tumor was supplied by right and left hepatic arteries. (A and B) Catheter-directed CTHA depicts planning target volumes of right (A) and left (B) hepatic arteries, dividing dosimetric plan into 2 independent halves for sublesional dosimetry. Left lobe hypodensity is cyst. (C) ^99mTc-MAA SPECT/CT shows good T/N ratio (6.1) of lateral tumor portion supplied by right hepatic artery but poor T/N ratio (1.4) of medial tumor portion supplied by left hepatic artery. Dosimetric plan of left hepatic artery planning target volume was deliberately escalated beyond safe limits to achieve predicted mean radiation absorbed dose of 133 Gy to tumor and 93 Gy to nontumorous liver, where progressive atrophy of left lobe was the anticipated collateral effect, that is, left radioembolization lobectomy intent. (D) Postradioembolization bremsstrahlung SPECT/CT shows good tumoral activity in both lateral and medial tumor portions, indicating technical success. C = cyst; L = left hepatic artery; Lat = lateral; Med = medial; R = right hepatic artery.

(A) Baseline triphasic CT scan of patient 2 shows recurrent HCC at segment IV resection margin. (B and C) Follow-up triphasic scans at 3 (B) and 6 (C) months after radioembolization show good tumor response (133 Gy), with progressive atrophy of left lobe (93 Gy), in keeping with left radioembolization lobectomy intent. Right lobe volume (27 Gy) remained stable. L = left lobe; T = tumor.