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trial lung 4DCT prospective

4DCT ventilation accurately predicted lung function after cancer resection

4DCT ventilation predicted postoperative FEV1, FVC, and DLCO with concordance coefficients of 0.88–0.91 in the LIME trial.

RadOncToday · ·1 min read

KEY POINTS

  • The prospective LIME trial enrolled patients with stage I–IIIA lung cancer being evaluated for anatomical resection. Of 65 consented patients, only 36 were evaluable after completing surgery, preoperative pulmonary-function testing and 4DCT, and postoperative testing.
  • The cohort predominantly had early-stage non-small cell lung cancer: 24 patients underwent lobectomy and 12 segmentectomy. Mean age was 67.9 years, and postoperative pulmonary-function tests were obtained a mean of approximately 130 days after surgery.
  • The 4DCT ventilation method used deformable registration and a mass-conserving density-change calculation to estimate regional lung ventilation. Predicted postoperative function was calculated by subtracting the proportion of ventilation located within the lung volume that was ultimately resected.
  • The prespecified primary endpoint required a concordance correlation coefficient of at least 0.85. The 4DCT-based method achieved 0.91 for FEV1, 0.89 for forced vital capacity, and 0.88 for diffusing capacity, meeting the endpoint for all three measures.
  • Conventional anatomical prediction performed similarly, with concordance coefficients of 0.90, 0.85, and 0.89, respectively. Differences between the two methods were not statistically significant, with all p values at least 0.47.
  • For FEV1 and forced vital capacity, 4DCT-based predictions had slightly lower root-mean-square errors than anatomical estimates: 0.29 versus 0.33 L and 0.44 versus 0.50 L, respectively. Both approaches tended to underestimate the actual postoperative values.
  • The two prediction methods differed by at least 10% in 17% of assessments. Visual case analysis suggested that 4DCT ventilation was more useful when regional lung function was heterogeneous, while conventional anatomical scaling sometimes performed better when ventilation was uniform.
  • The trial stopped early because of poor accrual and enrolled fewer than half of its planned 75 patients. It excluded patients denied surgery because of poor lung function and did not test whether providing 4DCT results to surgeons changed eligibility decisions, complications, quality of life, or treatment selection.

CLINICAL TAKEAWAY

4DCT ventilation can predict postoperative lung function accurately and may add patient-specific information when emphysema, tumour obstruction, or other factors create heterogeneous regional function. It is not yet superior to conventional anatomical calculation for routine surgical candidates, and an interventional trial is needed before it can guide operability decisions.

SOURCE

International Journal of Radiation Oncology, Biology, Physics