64-slice CT perfusion imaging for the early diagnosis of radiation-induced lung injury

Objective: To explore the value of 64-slice CT perfusion imaging (CTPI) in the early diagnosis of radiation-induced lung injury (RILI). Methods: Forty-eight patients with upper esophageal cancer resection underwent CTPI before and after radiotherapy, and the TNF-α and TGF-β₁ were measured from patient's peripheral blood. Serum cytokine,conventional CT appearances and CTPI parameters (rrBF, rrBV, rrPS) in patients with RILI (Group A) and non-RILI (Group B) were compared and analyzed. A randomized block design t-test was used for comparison of serum cytokines and perfusion values between the two groups. The Chi-square (χ²) test was used for comparison of detection rate between conventional CT and CTPI. Results: RILI occurred in 18 of 48 cases (18/48,Group A). In Group A, TNF-α and TGF-β₁ pre-and pos-radiation were (36.1 ± 15.0), (30.4 ±t 14.9) ng/L and (17.5 ±9.8), (14.3 ±7.6) μg/L, respectively, and there were no statistically significant differences (t=1.14, 1.10, P=0.264, 0.279). At half-dose time point of radiation,there were no significant differences for TNF-α and TGF-β₁ pre- and pos-radiation [(30.4 ± 14.9), (28.9 ± 14.7) ng/L and (14.3 ± 7.6), (14.4 ± 6.0) μg/L, respectively] between Group A and B (t=0.33, 1.23; P=0.746, 0.227). The rrBF, rrBV and rrPS of post-radiation from Group A were significantly higher than those of pre-radiation (t=5.67, 5.97, 6.11, P=0.000, 0.000, 0.000), the rrBF and rrBV of post-irradiation from Group B were significantly higher than those of pre-irradiation (t=6.52, 7.84, P=0.000, 0.000). There was no significant difference for rrPS in Group B pre- and post-radiation (t=1.36, P=0.178). There were significant differences for all perfusion values detected from radiation lung fields between Group A and B (t=2.32, 2.18, 6.04, P=0.025, 0.034, 0.000). Taking rrPS =1.28 as a threshold value on ROC, the sensitivity and specificity of CTPI for diagnosis of RILI were 77.8%, 93.3%,respectively, which were much higher than those (11.1%, 90.0%, respectively) of conventional CT (χ²=13.61, P=0.000). Conclusion: CTPI parameters may reflect the hemodynamic changes of post-radiation lung and have potential values for the early diagnosis of RILI. (authors)