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TH‐CD‐204‐02: Longitudinal Assessment of Radiation Treatment Response in Non‐Small Cell Lung Cancer Using Intravoxel Incoherent Motion Model Diffusion‐Weighted MRI
Author(s) -
Karki K,
Hugo G,
Ford J,
Weiss E
Publication year - 2015
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.4926249
Subject(s) - intravoxel incoherent motion , nuclear medicine , medicine , diffusion mri , effective diffusion coefficient , perfusion , magnetic resonance imaging , radiation therapy , radiology
Purpose: Perfusion‐insensitive apparent diffusion coefficient (ADC) is obtained using intravoxel incoherent motion (IVIM) model by separating perfusion compartment. The purpose of this study is to assess the longitudinal changes in the reference‐standard IVIM model ADC (ADC IVIM ) values of lung tumor volumes due to treatment response and to compare the relative longitudinal changes of the monoexponential model ADC values with that of ADC IVIM . Methods: Ten subjects had diffusion‐weighted MRI (DW‐MRI) scans at 0 week (pre‐treatment), and 3 and 6 weeks during radiotherapy in 1.5T MRI scanner. Respiratory triggering was applied to the echo‐planar DW‐MRI with TR=∼4500 ms, TE=74 ms, eight b‐values of 0–1000 µs/µm 2 , pixel size=1.98×1.98 mm 2 , slice thickness/gap=6 mm/1.2 mm and 7 axial slices. The ADC IVIM values and volumes of active tumors were compared longitudinally using paired t‐test. Changes in monoexponential model ADC values using the sets‐0–1000; 50–1000; 100–1000; 250–1000; 500–1000; 250, 500 and 1000; 250, 650 and 1000; 250, 800 and 1000; 250 and 800; and 250 and 1000 µs/µm 2 at 3 and 6 weeks relative to their corresponding baseline values at 0 week were also compared with that of ADC IVIM using all b‐values. Results: The ADC IVIM values increased significantly from 0 to 3 weeks, and from 3 to 6 weeks (p<0.05). The changes of monoexponential model ADC values relative to the baseline values for all sets were not significantly different from that of ADC IVIM at both 3 and 6 weeks (p>0.05) except for 0–1000, and 50–1000 µs/µm 2 sets at 3 weeks. The active tumor volume decreased significantly from 0 to 6 weeks. Conclusion: Active tumor ADC IVIM value increased and volume decreased during radiotherapy. No significant differences between the longitudinal changes of monoexponential ADC and ADC IVIM values were generally observed. DW‐MRI is efficient in showing active tumor functional and volume changes due to radiation treatment in lung cancer. This work was supported by Virginia Commonwealth University Massey Cancer Center pilot project A35242 (EW). There are no conflicts of interest.