Restriction Spectrum Imaging Differentiates True Tumor Progression From Immune-Mediated Pseudoprogression: Case Report of a Patient With Glioblastoma

Shadi Daghighi; Naeim Bahrami; William J Tom; Nicholas Coley; Tyler M Seibert; Jona A Hattangadi-Gluth; David E Piccioni; Anders M Dale; Nikdokht Farid; Carrie R McDonald

doi:10.3389/fonc.2020.00024

Restriction Spectrum Imaging Differentiates True Tumor Progression From Immune-Mediated Pseudoprogression: Case Report of a Patient With Glioblastoma

Front Oncol. 2020 Jan 28:10:24. doi: 10.3389/fonc.2020.00024. eCollection 2020.

Authors

Shadi Daghighi^{1

2}, Naeim Bahrami¹, William J Tom², Nicholas Coley³, Tyler M Seibert^{1

4}, Jona A Hattangadi-Gluth^{1

4}, David E Piccioni⁵, Anders M Dale^{1

2

5}, Nikdokht Farid^{1

2}, Carrie R McDonald^{1

4

6}

Affiliations

¹ Center for Multimodal Imaging and Genetics, University of California, San Diego, La Jolla, CA, United States.
² Department of Radiology, University of California, San Diego, La Jolla, CA, United States.
³ Department of Pathology, University of California, San Diego, La Jolla, CA, United States.
⁴ Department of Radiation Medicine, University of California, San Diego, La Jolla, CA, United States.
⁵ Department of Neurosciences, University of California, San Diego, La Jolla, CA, United States.
⁶ Department of Psychiatry, University of California, San Diego, La Jolla, CA, United States.

Abstract

Immunotherapy is increasingly used in the treatment of glioblastoma (GBM), with immune checkpoint therapy gaining in popularity given favorable outcomes achieved for other tumors. However, immune-mediated (IM)-pseudoprogression is common, remains poorly characterized, and renders conventional imaging of little utility when evaluating for treatment response. We present the case of a 64-year-old man with GBM who developed pathologically proven IM-pseudoprogression after initiation of a checkpoint inhibitor, and who subsequently developed true tumor progression at a distant location. Based on both qualitative and quantitative analysis, we demonstrate that an advanced diffusion-weighted imaging (DWI) technique called restriction spectrum imaging (RSI) can differentiate IM-pseudoprogression from true progression even when conventional imaging, including standard DWI/apparent diffusion coefficient (ADC), is not informative. These data complement existing literature supporting the ability of RSI to estimate tumor cellularity, which may help to resolve complex diagnostic challenges such as the identification of IM-pseudoprogression.

Keywords: brain tumors; diffusion imaging; immunotherapy; pseudoprogression; restriction spectrum imaging.

Publication types

Case Reports