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Leo Vael



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    P3.08 - Oligometastatic NSCLC (Not CME Accredited Session) (ID 974)

    • Event: WCLC 2018
    • Type: Poster Viewing in the Exhibit Hall
    • Track:
    • Presentations: 1
    • Moderators:
    • Coordinates: 9/26/2018, 12:00 - 13:30, Exhibit Hall
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      P3.08-18a - MR Perfusion and Spectroscopy to Distinguish Radiation Necrosis from Tumor Progression for Brain Metastases Treated with SRS (ID 13749)

      12:00 - 13:30  |  Author(s): Leo Vael

      • Abstract

      Background

      The occurrence of radiation necrosis after stereotactic radiosurgery (SRS) of cerebral metastases can interfere with response assessment. Progressive disease and radiation necrosis share common features on conventional and contrast-enhanced MRI, due to blood-brain barrier disruption and vasogenic edema.

      As stand-alone tools, magnetic resonance perfusion imaging and magnetic resonance spectroscopy (MRS) are promising in this setting. A combination of these functional imaging modalities will probably lead to an improved diagnostic accuracy.

      We report a case of a female patient (59 years) with stage IVB NSCLC (T3cN1M1c), with 1 bone and 3 brain metastases. In addition to conventional and contrast-enhanced MRI of the brain lesions, MRS and magnetic resonance perfusion imaging were performed.

      a9ded1e5ce5d75814730bb4caaf49419 Method

      The patient was treated on three brain lesions with SRS (20Gy, Volumetric modulated arc technique (VMAT, noncoplanar, 6MV photons, Varian Truebeam STX™). Treatment was controlled by Cone Beam CT and monitored by optical surface monitoring.

      Follow-up was performed every 10 weeks with conventional MRI and gadolinium-enhanced MRI with a 3-T unit (Magnetom, Siemens, Erlangen, Germany).

      Dynamic susceptibility contrast (DSC) T2-weigted MRI, dynamic contrast enhanced (DCE) T1-weigted MRI and MRS were performed after 5 months of SRS treatment in order to detect possible radiation necrosis. Uptake curves from voxels within the representative lesions were constructed based on DCE sequences.

      4c3880bb027f159e801041b1021e88e8 Result

      Conventional MRI and gadolinium-enhanced MRI of the brain 5 months after SRS detected several new lesions and apparent growth of the parieto-occipital previously treated lesion. The other treated lesions were reduced in volume.

      DSC, DCE and MRS, however, showed clear differences between the parieto-occipital lesion and the new lesions. While the new lesions had a high cerebral blood volume and flow (CBV, CBF) on DSC and early intense enhancement and subsequent wash-out on DCE, the parieto-occipital lesion had low CBV and CBF, slow progressive enhancement (DCE) and, upon MRS, a low Cho/NAA ratio (<1,8) and a high liquid peak.

      Follow-up after another 3 months revealed stable disease of all the SRS-treated lesions whereas the untreated lesions were progressive, suggesting that the imaging features of the parieto-occipital lesion are consistent with radiation necrosis.

      8eea62084ca7e541d918e823422bd82e Conclusion

      The differentiation between tumor progression and radiation necrosis is a common and challenging problem after SRS and may influence the decision between curative and palliative treatment. Our data suggest that a combination of DSC, DCE and MRS, in addition to contrast-enhanced and conventional MRI, could be useful to follow-up patients with brain metastases treated with SRS.

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