Shetal N. Shah MD, Abstract Co-Author: Nothing to Disclose

Gordon McLennan MD, Presenter: Data Safety Monitoring Board, B. Braun Melsungen AG Research Grant, C. R. Bard, Inc Consultant, C. R. Bard, Inc Consultant, Medtronic, Inc Consultant, Siemens AG Consultant, Eli Lilly and Company Scientific Advisory Board, Surefire Medical, Inc Scientific Advisory Board, Rene Medical

Shyam Srinivas MD, PhD, Abstract Co-Author: Siemens Healthcare

Radioembolization using Yttrium-90 (Y-90) microspheres is a treatment for unresectable hepatocellular carcinoma (HCC). A post-treatment Y-90 PET/CT scan can help determine microsphere distribution. We studied the correlation of post treatment Y-90 PET/CT hepatic distribution, with calculated radiation dose delivered to tumor and normal liver, and therapy response assessment on subsequent CT and MRI in transcatheter treated HCC patients.

HIPAA compliant, retrospective chart and imaging review of 57 treated patients (101 hepatic tumors) were completed. Specific activities (Bq/mL) for treated tumor and normal liver tissue were calculated from the Y-90 PET/CT scans based on overlay tumor contouring from pre-procedure triphasic liver CT and MRI. Tumor response on subsequent imaging was assessed using mRECIST.

The mean dose per tumor was 166.45 Gy (mode 90-120 Gy; treatment dose range 0-570 Gy). Tumor response by mRECIST correlated with dose delivered, with complete response (CR) significantly higher in lesions receiving >300 Gy, and stable disease (SD) being higher in lesions receiving <60 Gy. Normal liver tissue received a mean dose of 66.25 Gy. 8/15 (53%) pts who received a dose of radiation greater than 80 Gy to normal liver displayed signs of hepatotoxicity.

Radiation dose HCC after Y-90 dose radioembolization is similar to the brachytherapy dose used to treat other cancers. Lesion dose estimated at >300 Gy resulted in CR, while lesions receiving mean dose <60 Gy had SD by mRECIST.

To date, few study have reported the correlation between dose injected, microshpere distribution, dose quantification, and radiographic response after Y-90 treatment in unresectable transcatheter treated HCC. This knowledge may help optimize outcomes and reduce adverse events.

Shah, S, McLennan, G, Srinivas, S, Determining Correlation between Post-radioembolization Y-90 PET/CT Scan, Estimated Lesion Dosimetry, and Radiographic Response of Transcatheter Treated Unresectable Hepatocellular Carcinoma.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14017987.html