We report a 57-year-old male non-smoker who underwent "thoracoscopic radical resection of right lower lung cancer (single-hole method)" under general anaesthesia in December 2014. Postoperative pathology showed right lower lung adenosquamous carcinoma (squamous cell carcinoma accounted for 70%, and adenocarcinoma accounted for 30%). Nodules with a diameter of 2 cm were observed at a distance of 4 cm from the bronchial margin. No cancer was involved in the bronchial margin. Metastatic carcinoma was found in 1 para-bronchial lymph node. The postoperative stage was pT1bN1M0. Human epidermal growth factor receptor (EGFR) gene mutation detection showed 20-ins. Four cycles of NP (vinorelbine + cisplatin) adjuvant chemotherapy were performed. In June 2017, a chest computed tomography (CT) plain scan and an enhanced scan showed a mass shadow of the right upper lobe and segmental atelectasis of the right upper lobe. Recurrence was considered, and enlarged lymph nodes were seen below the carina. The histopathologic findings of the fibreoptic bronchoscopy biopsy demonstrated an invasive carcinoma of the right main bronchus. Abdominal CT, brain MRI and whole-body bone imaging (emission computed tomography; ECT) showed no signs of distant metastasis. The diagnosis was recurrence of lung cancer, rT2N2M0, stage IIIB. Radical concurrent radiochemotherapy was performed under the guidance of IVIM functional MRI.
The radiotherapy regimen was as follows. A Versa HD medical linear accelerator was used, and a 4D CT scanner was used. The upper boundary of the scanning range was cricoid cartilage, and the lower boundary was lumbar 2 cone. The thickness of the scanning layer was 5 mm, and the thickness of the tumour area was 2.5 mm. A GE 3.0T superconducting magnetic resonance scanner (GE Signa HDxt 3.0T MR, GE Corporation), 16-channel abdominal phased array coil, and GE AW4.6 workstation were used. The MRI scan sequences included the T2WI lipid pressure in the transverse position, the T2WI lipid pressure sequence in the coronary position and the IVIM. The MADC image post-processing software of the FuncTool software package was used to obtain three kinds of parameterized images: slow apparent diffusion coefficient (ADC), D* (fast ADC) and f of fast ADC. Diffusion coefficient ADC images were obtained by conventional DWI post-processing (Fig. 1). Based on the results of the chest CT enhanced scans and IVIM imaging, the tumour tissue in the lung was delineated as the gross tumour volume (GTV), and the subcarinal lymph node was delineated as the GTV of the cervical lymph node (GTVnd). The clinical target volume (CTV) was placed 0.8 cm outside the GTV. The planned target volume (PTV) was expanded uniformly according to the positioning error of the unit (approximately 0.5 cm). The P-GTV dose was 66 Gy/30 F/6 W, and the P-CTV dose was 60 Gy/30 F/6 W (Fig. 2A). After 4 weeks of radiotherapy, the same scanning and post-processing methods were used to review the results after radiotherapy (Fig. 1), and the GTV and CTV were re-drawn according to the post-treatment images. Changes in tumour size and in various parameters were observed. According to the IVIM images before and after treatment, another tumour treatment resistance area was outlined and named the GTV-r. The dose of the GTV-r was increased, and the physical dose of radiotherapy reached 44 Gy/20 F + 24 Gy/10 F (the biological dose was 53.7 Gy + 29.8 Gy = 83.5 Gy) (Fig. 2B). The concurrent chemotherapy regimen was weekly docetaxel combined with cisplatin. One month after treatment, chest and abdominal CT and cranial MRI were performed again. The mass shadow of the right hilar area had disappeared, and the upper lobe of the right lung had re-expanded. The curative effect was evaluated as complete remission (Fig. 3). Grade 2 radiation pneumonitis occurred during treatment and returned to normal after treatment. After regular re-examination, the patient's last follow-up was April 17, 2020, and there were no signs of recurrence or metastasis. The patient's performance status (PS) score was 0 points.