Frequency and Risk Factors for Air Embolism in Computed Tomography Fluoroscopy-Guided Biopsy of Lung Tumor With the Use of Noncoaxial Automatic Needle.

PURPOSE: The aim of the study is to analyze incidence and risk factors for air embolism during computed tomography (CT) fluoroscopy-guided lung biopsies using noncoaxial automatic needle. MATERIALS AND METHODS: Between February 2014 and December 2019, 204 CT fluoroscopy-guided lung biopsies (127 men; mean age, 70.6 years) using noncoaxial automatic needle under inspiratory breath holding were performed. We retrospectively evaluated the incidence of air embolism as presence of air in the systemic circulation on whole-chest CT images obtained immediately after biopsy. Risk factors of the patient, tumor and procedural factors (size, location and type of nodule, distance from the pleura, the level of the lesion relative to the left atrium, emphysema, patient position, penetration of a pulmonary vein, etc) were analyzed. RESULTS: The technical success rate was 97.1%. Air embolism was radiologically identified in 8 cases (3.92%, 7 males; size, 21.6 ± 18.2 mm; distance to pleura, 11.9 ± 14.5 mm). Two patients showed overt symptoms and the others were asymptomatic. Independent risk factors were needle penetration of the pulmonary vein ( P = 0.0478) and higher location relative to left atrium ( P = 0.0353). Size, location and type of nodule, distance from the pleura, emphysema, patient position, and other variables were not significant risk factors. As other complications, pneumothorax and alveolar hemorrhage were observed in 57.4% and 77.5%, respectively. CONCLUSIONS: In CT fluoroscopy-guided lung biopsy using the noncoaxial automatic needles, radiological incidence of air embolism was 3.92%. Given the frequency of air embolism, it is necessary to incorporate this into postprocedure imaging and clinical evaluation.

Evaluation of Temperature Distribution Around the Probe in Cryoablation of Lipiodol-Mixed-Tissue Phantom.

PURPOSE: To determine whether lipiodol, which has low thermal conductivity, influences ice ball formation during cryoablation of a lipiodol-mixed-tissue phantom. MATERIALS AND METHODS: Lipiodol-mixed-tissue phantoms were created by injecting lipiodol (4-6 ml) into the renal arteries of ex vivo porcine kidneys (lipiodol group). A cryoprobe (CryoHit™ Needle S) with a holder that was set with thermocouples at various positions around the cryoprobe was inserted. After freezing for 300 s, the followings were evaluated: ice ball size on CT, temperature distribution around the cryoprobe, and calculated distances at 0 °C and - 20 °C. Each variable was compared between lipiodol group (n = 6) those obtained in a control group without lipiodol injection (n = 6). RESULTS: Mean ice ball diameter (width/length) on CT was 22.1 ± 2.3/22.9 ± 2.3 mm in the lipiodol group and 21.6 ± 0.7/22.2 ± 1.3 mm in the control group. Mean cryoprobe temperature was - 118 ± 3.0 °C in the lipiodol group and - 117 ± 2.6 °C in the control group. In both groups, temperature at the 3 mm thermocouple reached approximately - 50 °C and was < 0 °C within ~ 10 mm of the cryoprobe. Temperature of 0/- 20 °C occurred at a mean distance from the cryoprobe of 11.1 ± 0.5/6.9 ± 0.4 mm in the lipiodol group and 11.0 ± 0.2/6.9 ± 0.2 mm in the control group. There was no significant difference in any variable between the groups. CONCLUSION: The inclusion of lipiodol in a tissue phantom had no negative effects on ice ball formation that were related to thermal conductivity.