Abstract Details

Title Semi-Automated Longitudinal Lesion Tracking In PACS Reveals High Proportion of Metastatic Lesions Showing Mixed Response To Radiosurgery

Topic Neuro-oncology

Presentation(s) P14 - Poster Session 14 (11:45 AM-12:45 PM)

Poster/Presentation
Number 4-001

Objective Demonstrate a PACS-integrated method of assessing multiple follow-up MR scans to characterize treatment response of individual metastatic lesions.

Background Brain metastases are the most common neoplasm of the brain. Gamma-Knife (GK) allows precise radiation of individual lesions. In contrast, classical methods of assessing treatment response use the overall sum of diameters, failing to convey how individual lesions contribute differently to overall tumor burden.

Design/Methods

100 patients who underwent GK for brain metastases were randomly selected and scanned for exclusion criteria. Lesion tracking was performed using PACS-integrated Lesion Tracking Tool (LTT) (Visage Imaging) beginning with the GK-scan and followed for 2-7 scans. Lesions ≥10mm longest diameter (LD) were classified as progressive, receding, or stable if LD increased ≥20% from nadir, decreased ≥30% from baseline, or neither, respectively. For lesions <10mm LD a minimum change of at least 3mm was needed to classify as changing. By comparing the different lesions within a patient, treatment response was classified as homogenous or as mixed at the last available follow-up study.

Results 83 patients were eligible; 387 lesions were measured [mean follow-up: 320 days (Range: 43-1374)]. 71 patients had >1 lesion. At last date of follow-up, 82%, 8.5%, 7%, 2.8% of patients had a mixed; homogenously decreasing, stable, and increasing response to treatment, respectively. Proportion of patients with mixed response increased from 65% in patients with 2 lesions (n=26) to 95.5% in those with >4 (n=22). Follow-ups performed within 90 days post-intervention showed mixed response in 63.6% of patients.

Conclusions Assessing treatment response of metastatic lesions in the brain allows personalized treatment planning. Our study shows that metastatic lesions in a patient can differ in their response to the same treatment, arguing in favor of tracking individual lesions. We recommend incorporation of PACS-integrated lesion tracking in clinical practice to better characterize growth changes in patients with metastatic lesions.

Authors/Disclosures
Gabriel I. Cassinelli Petersen (University of Tübingen) PRESENTER	Mr. Cassinelli Petersen has nothing to disclose.
	No disclosure on file
	No disclosure on file
Leon Jekel	Mr. Jekel has nothing to disclose.
Sara Merkaj (Yale School of Medicine)	Mrs. Merkaj has nothing to disclose.
Ryan C. Bahar (Yale School of Medicine)	Mr. Bahar has nothing to disclose.
	No disclosure on file
	No disclosure on file
	No disclosure on file
Antonio M. Omuro, MD, FAAN (Stanford University)	Dr. Omuro has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Ono Therapeutics. Dr. Omuro has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Telix. Dr. Omuro has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Curevac. The institution of Dr. Omuro has received research support from NIH. The institution of Dr. Omuro has received research support from Arcus Biosciences. The institution of Dr. Omuro has received research support from Denovo Biopharma. The institution of Dr. Omuro has received research support from Ono Pharmaceutical. The institution of Dr. Omuro has received research support from Servier. The institution of Dr. Omuro has received research support from Nanopharmaceuticals. The institution of Dr. Omuro has received research support from Denovo.
Mariam Aboian, MD, PhD (Yale University)	Dr. Aboian has a non-compensated relationship as a Principal Investigator with Visage Imaging that is relevant to AAN interests or activities.

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