Effectiveness of Cytological Diagnosis with Outer Cannula Washing Solution for Computed Tomography-Guided Needle Biopsy.

Rationale and Objectives We evaluated the availability of cytological diagnosis with outer cannula washing solution (C-OCWS) as a clinical diagnostic tool for computed tomography (CT)-guided needle biopsy. Materials and Methods We retrospectively assessed 109 consecutive patients (71 males, 38 females; median age 68 years), who underwent CT-guided needle biopsy. In all patients, the specimens sampled by the inner needle were used for histological diagnosis, and those taken from the outer cannula were rinsed with 0.9% saline solution: outer cannula washing solution for cytological diagnosis. The accuracy of C-OCWS in addition to histological diagnosis were compared with that of histological diagnosis alone. We used binary logistic regression analysis to determine the variables associated with diagnostic accuracy for malignancy and lesion characteristics. Results The C-OCWS method precisely diagnosed 7 (6.4%) malignant lesions (i.e., effective cases) in the 109 patients characterized as “negative for malignancy” via histological diagnosis alone. The accuracy of the combination of C-OCWS and histological diagnoses was significantly higher than that of histological diagnosis alone (0.95 vs. 0.89, respectively; p = 0.023). Multivariate logistic regression analysis showed that increasing only a marginal ratio (failure rate for proper position of biopsy needle within the tumor) was independently associated with a high rate of effective cases (p = 0.003). Conclusion C-OCWS may be helpful for improving the quality of CT-guided needle biopsy, and is a simple method that may not necessarily increase the patients’ physical burden.