The Effect of Hounsfield Unit Value on the Differentiation of Malignant/Benign Mediastinal Lymphadenopathy and Masses Diagnosed by Endobronchial Ultrasonography.

Aim: In cases where standardized maximum uptake (SUVmax) values in positron emission tomography (PET-CT) were not sufficient to differentiate mediastinal lymphadenopathy and masses from malignant or benign, the contribution of Hounsfield unit (HU) values in thorax computed tomography to the diagnosis was evaluated.

Material method: The study was conducted by evaluating the data of 182 patients between 2019 and 2023. HU values on non-contrast thorax computed tomography and PET-CT SUV_max values of biopsied masses and lymph nodes were compared with histopathological diagnoses.

Results: Patients, 58 females (31.9%) and 124 males (68.1%), who underwent EBUS were included in the study. Biopsies were taken from 233 stations (199 lymph nodes, 34 masses) from 182 patients. A total of 135 of the biopsies taken from 233 stations were histopathologically malignant and 98 were benign. While PET-CT SUV_max values of cases with benign histopathology were 4.5 ± 3.5, it was 7.6 ± 4.2 in patients with malignant pathology (p<0.05). The HU value on non-contrast thorax tomography in patients with benign histopathology was 43.1 ± 15.7, and in patients with malignant histopathology it was 40.5 ± 13.7 (p>0.05). When HU was compared according to lung cancer type, it was found to be significantly higher in non-small cell lung cancer (p=0.035). A weak (r=0.182) positive and significant relationship (p<0.01) was found between PET-CT values and HU values in thorax computed tomography.

Conclusion: While positron emission tomography maintains its importance in the differentiation of mediastinal lymphadenopathy and masses from malignant to non-malignant, it was concluded that HU values in computed tomography are not sufficient to distinguish malignant/non-malignant.