Determining the optimal puncture site of CT-guided transthoracic needle aspiration biopsy for the diagnosis of tuberculosis

Background The purpose of this study was to determine the optimal puncture site of computed tomography (CT)-guided transthoracic needle aspiration biopsy for the diagnosis of tuberculosis (TB) by the comparison of clinical and radiological characteristics of TB patients stratified to different histopathological results. Methods We retrospectively analysed the data of clinically diagnosed TB patients with negative laboratory results between July 2016 and June 2018. Biopsy specimens were obtained from patients for Ziehl-Neelsen (Z-N) staining and TB-DNA. Results For the 356 TB patients, the positive rate of TB-DNA was 70.9%, which was significantly higher than that of Z-N staining (46.4%, P<0.001). The positive rate of lesions from upper lobe (76.4%, 155/203) was significantly higher than that from lower lobe (63.1%, 89/141, P=0.008). The mean of ΔCT density for positive histologic group (12.84±6.81 HU) was lower than that for negative histologic group (28.32±9.82 HU, P<0.001). ROC curve analysis revealed that a density-based cut-off value of 20.5 HU should be set as the cut-off values for determining the optimal puncture site. Conclusions Our data demonstrates that the molecular diagnostics has superiority over Z-N staining for detecting MTB from lung aspirates. The lung biopsies from upper lobe were more likely to yield positive histologic results than those from lower lobe. In addition, the enhancement of 20.5 HU by CT scans should be set as the cut-off values for determining the optimal puncture site that would facilitate an efficient diagnosis of pulmonary TB.