Faculty Bibliography

Assess computed tomography (CT) imaging characteristics after percutaneous cryotherapy for lung cancer.A retrospective IRB-approved analysis of 40 patients who underwent nonsurgical treatment for primary stage 1 lung cancer performed from January 2007 to March 2011 was included in this study. All procedures were performed using general anesthesia and CT guidance. Follow-up imaging with CT of the chest was obtained at 1 month, 3 months, 6 months, and 12 months postprocedure to evaluate the ablated lung nodule. Nodule surface area, density (in Hounsfield units), and presence or absence of cavitations were recorded. In addition, the degree of nodule enhancement was also recorded. Patients who were unable to obtain the aforementioned follow-up were excluded from the study.Thirty-six patients underwent percutaneous cryoablation with men to women ratio of 75% with mean age for men 74.6 and mean age for women 74.3 years of age. The average nodule surface area preablation and postcryoablation at 1-, 3-, 6-, and 12-month follow-ups were 2.99, 7.86, 3.89, 3.18 and 3.07[REPLACEMENT CHARACTER]cm, respectively. The average precontrast nodule density before cryoablation was 8.9 and average precontrast nodule density postprocedure at 1, 3, 6, and 12 months follow-ups were 8.5, -5.9, -9.4, and -3.8 HU, respectively. There is increased attenuation of lung nodules over time with an average postcontrast enhancement of 11.4, 18.5, 16.1, and 25.7 HU at the aforementioned time intervals. Cavitations occurred in the cryoablation zone in 53% (19/36) of patients. 80.6% (29/36) of the cavitations in the cryoablation zone resolved within 12 months. Four patients (11%) had recurrence of tumor at the site of cryoablation and none of the patients had satellite or distant metastasis.Our study shows that patients who underwent cryotherapy for lung nodules treatment had characteristic changes on follow-up CT including. The surface area of the nodule increases at the 1-month follow-up with subsequent gradual decrease in the surface area. Decreased nodule density (Hounsfield units) at each interval follow-up is associated with complete ablation of the lung cancer whereas increasing nodule density was suggestive of recurrence. Cavity formation within the region of the ablated nodule, most of which typically resolved within the first 3 to 6 months. Nodule enhancement is difficult to assess because of the limited data sets that are available.

PURPOSE: The aim of this study was to understand the imaging features of fluorine-18 fluorodeoxyglucose ((18)F-FDG) PET-computed tomography (CT) in postcryoablation lung cancer patients that could help predict recurrence. METHODS: We identified 28 patients with 30 lesions treated by means of percutaneous cryoablation for stage I non-small-cell lung cancer. Two experienced nuclear radiologists blindly reviewed baseline images and follow-up (18)F-FDG PET-CT scans for a minimum of 24 months, with discrepancy in interpretation resolved by consensus. Nineteen lesions had undergone baseline PET-CT studies, whereas 11 lesions had undergone only baseline CT studies. Follow-up PET-CT studies were analyzed for up to 24 months, whereas the recurrence-free survival analysis was performed for 36 months. RESULTS: The average maximum standardized uptake value (SUV(max)) at baseline (n = 19) was 5.2 +/- 3.9 and the average CT area at baseline was 2.2 +/- 1.6 cm(2). Only the CT area was significantly different between recurring and nonrecurring lesions at baseline (P = 0.0028). The Kaplan-Meier survival analysis showed that dichotomizing lesions around 2 cm on CT did not result in a statistically significant survival difference (hazard ratio = 1.42, 95% confidence interval: 0.63-2.21). The average SUV(max) at first follow-up was 1.9 +/- 1.8 for 27 lesions, whereas the average SUV(max) of recurrent lesions was 2.2 +/- 2.2 and that of nonrecurrent lesions was 1.5 +/- 0.3 (P = 0.17). Six lesions had SUV(max) more than or equal to 2.5 within 24 months, all of which recurred in the ablation zone. CONCLUSION: (18)F-FDG PET-CT is a valuable tool for determining treatment response and for distinguishing benign from malignant lesions after cryoablation. The CT area was most predictive of future recurrence at baseline, whereas SUV(max) more than or equal to 2.5 was most predictive of future recurrence at first follow-up.