Is pulsed saturation transfer sufficient for differentiating radiation necrosis from tumor progression in brain metastases?

Rachel W Chan; Wilfred W Lam; Hanbo Chen; Leedan Murray; Beibei Zhang; Aimee Theriault; Ruby Endre; Sangkyu Moon; Patrick Liebig; Pejman J Maralani; Chia-Lin Tseng; Sten Myrehaug; Jay Detsky; Mary Jane Lim-Fat; Katrina Roberto; Daniel Djayakarsana; Bharathy Lingamoorthy; Hatef Mehrabian; Benazir Mir Khan; Arjun Sahgal; Hany Soliman; Greg J Stanisz

doi:10.1093/noajnl/vdae132

Is pulsed saturation transfer sufficient for differentiating radiation necrosis from tumor progression in brain metastases?

Neurooncol Adv. 2024 Jul 29;6(1):vdae132. doi: 10.1093/noajnl/vdae132. eCollection 2024 Jan-Dec.

Authors

Rachel W Chan¹, Wilfred W Lam¹, Hanbo Chen², Leedan Murray¹, Beibei Zhang³, Aimee Theriault², Ruby Endre¹, Sangkyu Moon¹, Patrick Liebig⁴, Pejman J Maralani⁵, Chia-Lin Tseng², Sten Myrehaug², Jay Detsky², Mary Jane Lim-Fat⁶, Katrina Roberto⁶, Daniel Djayakarsana^{1

7}, Bharathy Lingamoorthy¹, Hatef Mehrabian¹, Benazir Mir Khan², Arjun Sahgal², Hany Soliman², Greg J Stanisz^{1

7

8}

Affiliations

¹ Physical Sciences Platform, Sunnybrook Research Institute, Toronto, Ontario, Canada.
² Department of Radiation Oncology, Sunnybrook Health Sciences Centre & University of Toronto, Toronto, Ontario, Canada.
³ Department of Medical Physics, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada.
⁴ Siemens Healthcare GmbH, Erlangen, Germany.
⁵ Department of Medical Imaging, Sunnybrook Health Sciences Centre & University of Toronto, Toronto, Ontario, Canada.
⁶ Division of Neurology, Department of Medicine, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada.
⁷ Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada.
⁸ Department of Neurosurgery and Pediatric Neurosurgery, Medical University of Lublin, Lublin, Poland.

Abstract

Background: Stereotactic radiosurgery (SRS) for the treatment of brain metastases delivers a high dose of radiation with excellent local control but comes with the risk of radiation necrosis (RN), which can be difficult to distinguish from tumor progression (TP). Magnetization transfer (MT) and chemical exchange saturation transfer (CEST) are promising techniques for distinguishing RN from TP in brain metastases. Previous studies used a 2D continuous-wave (ie, block radiofrequency [RF] saturation) MT/CEST approach. The purpose of this study is to investigate a 3D pulsed saturation MT/CEST approach with perfusion MRI for distinguishing RN from TP in brain metastases.

Methods: The study included 73 patients scanned with MT/CEST MRI previously treated with SRS or fractionated SRS who developed enhancing lesions with uncertain diagnoses of RN or TP. Perfusion MRI was acquired in 49 of 73 patients. Clinical outcomes were determined by at least 6 months of follow-up or via pathologic confirmation (in 20% of the lesions).

Results: Univariable logistic regression resulted in significant variables of the quantitative MT parameter 1/(R_A·T_2A), with 5.9 ± 2.7 for RN and 6.5 ± 2.9 for TP. The highest AUC of 75% was obtained using a multivariable logistic regression model for MT/CEST parameters, which included the CEST parameters of AREX_{Amide,0.625µT} (P = .013), AREX_NOE,0.625µT (P = .008), 1/(R_A·T_2A) (P = .004), and T₁ (P = .004). The perfusion rCBV parameter did not reach significance.

Conclusions: Pulsed saturation transfer was sufficient for achieving a multivariable AUC of 75% for differentiating between RN and TP in brain metastases, but had lower AUCs compared to previous studies that used a block RF approach.

Keywords: brain metastasis; chemical exchange saturation transfer; magnetic resonance imaging; magnetization transfer; radiation necrosis; saturation transfer.