Novel Early Response Biomarkers for Renal Cell Carcinoma – New Data Is Presented at RSNA Meeting, 29 Nov-1 Dec 2017, Chicago, USA

IAG is to present at annual meeting of the Radiological Society of North America (RSNA) their latest scientific work in advanced quantitative image analysis in renal cell carcinoma (RCC) in collaboration with the Peter MacCallum Cancer Center, Melbourne, Australia.

The developed multi-parametric MRI analysis methodology including DCE-MRI revealed RCC treatment efficacy where RECIST-based approaches are not adequate.

The RSNA Selection Committee has accepted the scientific abstract for oral presentation at the 2017 RSNA Annual Meeting, to be held in Chicago, USA, held from November 25 ā€“ Dec 1. Dr. Diana Roettger, IAGā€™s Head of Scientific and Medical Affairs and Dr. Shankar Siva, the prime investigator in the study will attend the meeting and present the data.

Multiparametric MRI for Renal Cell Carcinoma: Assessment of Tumor Response after Stereotactic Ablative Body Radiotherapy

Oral Presentation: Tuesday 11:10-11:20 AM | SSG16-05 | Room: S104A
Abstract ID: 17012299
Authors: H Reynolds, PhD, B Parameswaran, MD; M E Finnegan, PhD; D Roettger, PhD; P Jackson, PhD; T Kron, PhD, DIPLPHYS; et al.

PURPOSE
Response assessment of renal cell carcinoma (RCC) after stereotactic ablative body radiotherapy (SABR) using size criteria from CT is challenging, as changes may evolve over months and even years post-therapy. The purpose of this study was to analyze early diffusion and perfusion changes in RCC tumors shown by multiparametric MRI after SABR, and to assess whether any changes are associated with overall treatment response.

METHOD AND MATERIALS
Twelve patients in a prospective Phase Ib clinical trial were analyzed, where patients with RCC tumour size <5cm diameter received a single fraction of 26 Gy and larger lesions received three fractions of 14 Gy. Multiparametric MRI including diffusion weighted (DWI) and dynamic contrast-enhanced (DCE) imaging was acquired at baseline and approximately three weeks and three months after SABR. Apparent diffusion coefficient (ADC) maps were computed from DWI data, heuristic parametric and pharmacokinetic maps using the extended Tofts model were fitted to the DCE data. Tumour volumes were contoured and statistics including histogram metrics extracted. Changes in DWI and DCE MRI characteristics were correlated with change in tumour volume shown by late follow-up CT (average 28 months after baseline CT, range 17-40 months) and with the Response Evaluation Criteria in Solid Tumors (RECIST) criteria.

RESULTS
The ADC mean, median and kurtosis measures increased in most patients at the third MRI scan indicating increased diffusion after SABR, however there was no clear correlation with the change in tumour volume. DCE analysis showed strong correlations between the change in enhancement curve type and the change in tumor volume. Pharmacokinetic maps showed a positive correlation between tumour volume change and the difference in Ktrans, and a negative correlation with the change in Ve, at the third MRI scan.

CONCLUSION
Voxel-based analysis of tumors using DCE MRI shows promise for early prediction of overall tumour response, and may provide a useful biomarker for guiding patient management which is more reliable than RECIST criteria. DWI analysis did not provide a strong early indicator of treatment response.

CLINICAL RELEVANCE/APPLICATION
DCE MRI after SABR treatment for RCC may provide novel early response biomarkers which are more reliable than conventional CT based geometric RECIST response criteria.

DCE-MRI parametric maps at (a) baseline and (b) follow-up scan 2 for patient 1, showing (left ā€“ right) contrast enhancement curve type (green = plateau, red = washout, blue = persistent), IRE, Tonset, and AUC. Tumour contour in (a) black and (b) white for contrast.

*All Parametric Maps calculated in DYNAMIKA, IAG’s Proprietary Platform for Clinical Trial Data Management and Analysis.