Abstract: Objective To evaluate the application of magnetic resonance diffusion-weighted imaging (DWI) for CT-guided percutaneous transthoracic lung biopsy (PTLB) in pulmonary space-occupying lesion patients with obstructive pneumonia or pulmonary atelectasis.Methods A total of 269 pulmonary space-occupying lesions patients with obstructive pneumonia or pulmonary atelectasis who were admitted to Xuzhou Hospital of Traditional Chinese Medicine and underwent PTLB from July 1, 2019 to December 31, 2022 were selected. The patients were randomly divided into two groups in a ratio of 1:1:a DWI+CT-guided group and a CT-guided group. The DWI+CT-guided group underwent DWI and CT scanning within seven days, while the CT-guided group was subject to CT scanning. Both groups were compared for the accuracy of first PTLB puncture, with the pathological results after surgical resection as the golden standards.Results There were 70 patients in the DWI+CT group and 72 patients in the CT group. The accuracy of PTLB was 98.57% (69/70) for the DWI+CT-guided group and 87.50% (63/72) for the CT-guided group, with statistical differences (P=0.010). Conclusions The combined use of DWI before puncture can improve the accuracy of first CT-guided PTLB.