Dr. Detterbeck has pointed out that there were some false-positive and false-negative results with our procedure,1 which might cause an incorrect treatment plan. While we have no objection to his comments, our data just show the accuracy of differentiation among atypical adenomatous hyperplasia (AAH), bronchioloalveolar carcinoma (BAC), and adenocarcinoma (AD) by using CT number analysis. While visual analysis can hardly differentiate the nodules, our CT number analysis can evaluate the ground-glass opacity (GGO) nodules with objectivity. If the nodules showed the “two-peak pattern” on CT number histogram, we can deny AAH. Even if BAC had a 75% percentile CT number that was lower than − 584 Hounsfield units (HU), the malignant grade should be lower than those for which the 75% percentile CT number was higher than − 584 HU. Therefore, those BACs with a low 75% percentile CT number could be observed by CT, which would not miss the chance of curative treatment after follow-up. Dr. Detterbeck pointed out that 15% of ADs and 31% of BACs could be incorrectly classified with mean CT number, causing incorrect surgical procedures. However, in Japan, the final indication of wedge resection for BAC is usually determined by intraoperative frozen section. If the intraoperative frozen section showed AD, the operation is usually converted to segmentectomy or lobectomy. Furthermore, while 31% of BACs could be classified as AD with mean CT number, those BACs with high mean CT number could have higher malignant grade than those with a low mean CT number. Therefore, those BACs with a high mean CT number might be better to be treated with segmentectomy than wedge resection.