Prognosti̇c role of diffusion weighted MRİ in inoperable lung cancer

Purpose: Our study aims to determine the role of Diffusion MRG in evaluating the response of the bulk to chemotherapy in Stage III-IV Lung Cancer (Inoperable Lung Cancer). Materials and Methods: The ADC values of the patients, who were diagnosed with Stage III-IV Lung Cancer after CT between November 2015 -December 2016 before Chemotherapy (CTh) and after the 3 rd cure, were determined in the study. Thirty-two patients were included in the study . The response of the bulk was evaluated according to RECIST Criteria by taking the longest size of the bulk as basis simultaneously with Diffusion MRI. The study was conducted prospectively. The Thorax MRI and Diffusion MRI images taken 1 week before the CT and 3 weeks after the 3 rd Cure were examined in the work station. The b factor was taken as 50, 400, 800 sn / mm² in Diffusion-weighted images. Results: The average age of the patients was 63.8 years (±8.45, 44-84); 31 patients were male and 1 patient was female. 21 (65.6%) of the patients were diagnosed with Non-Small Cell Lung Cancer (NSCLC), and 11 of them were diagnosed with Small-Cell Lung Cancer (SCLC). 11 (34.4%) of those who were diagnosed with NSCLC were diagnosed with adeno-cancer, 9 (28.1%) were diagnosed with squamosal cell cancer and 1 (3.1%) was diagnosed with Large Cell Cancer Histopathology. Without considering the progression and regression status, the ADC-Mean value before chemotherapy was 0.957 (±0.310) x 10ˉ³; while the ADC-Mean value after chemotherapy became 1,122 (±0.303) x 10ˉ³, which is statistically significant (p=0.006). Without considering progression and regression status, the average ADC value of the NSCLC group was 1.026 (±0.286) x 10ˉ³, while the ADC values became 1.266 (±0.297) x 10ˉ³, and the ADC value change was found to be significant (p=0.044). Without considering the progression and regression status, the average ADC value before chemotherapy in those who were diagnosed with SCLC was 0.825 (±0.325) x 10ˉ³, while the average ADC values after the chemotherapy became 1.038 (±0.311) x 10ˉ³. The ADC values after the Chemotherapy were found to be higher and statistically significant (p=0.046). The average bulk size before the treatment was 54.4mm (±23.6), and it was measured as 37.7 mm (±19.9) after the treatment. Discussion: In our study, the change in the ADC values after chemotherapy increased at a significant level in the regression group. On the other hand, although the ADC decrease in the progression group was not as high as that of the regression group, it was found to be significant. Without considering the progression and regression status, no statistically significant difference was determined in the ADC change values of the NSCLC Group and SCLS Group. The p values were found as 0.044 and 0.046, respectively. The ADC change in the NSCLC Group was found to be significant only in the squamous-cell cancer group, and the p value was calculated as 0.028. The ADC change was not found to be significant in Adeno-cancer and large-cell group. As the TNM stage increased, it was observed that the ADC value v decreased; however, only the change in N stage was found to be significant between the groups. On the other hand, in determining the TNM stage, the diffusion and thorax MRG tests may be used. However, studies with wider series and multiple centers are needed in order to determine the actual role of ADC in the response to chemotherapy. Key Words: Inoperable lung cancer, treatment response, diffusion weighted MR imaging.