Prathipati Archana, Manthri Ranadheer Gupta, Subramanian Bala Venkat, Das Pranabandhu, Jilla Swapna, Mani Sangeetha, J Anitha Kumari, Sarala Settipalli, Kottu Radhika, Kalawat Tek Chand, Naidu Kotiyala Venkata Jagannath Rao
Department of Radiation Oncology, Sri Venkateswara Institute of Medical Sciences, Tirupati, Andhra Pradesh, India.
Department of Nuclear Medicine, Sri Venkateswara Institute of Medical Sciences, Tirupati, Andhra Pradesh, India.
Asia Ocean J Nucl Med Biol. 2017 Spring;5(2):75-84. doi: 10.22038/aojnmb.2017.8706.
F-fluorodeoxyglucose positron emission tomography/computed tomography (F-FDG PET-CT) is a well-used and established technique for lung cancer staging. Radiation therapy requires accurate target volume delineation, which is difficult in most cases due to coexisting atelectasis. The present study was performed to compare the F-FDG PET-CT with contrast enhanced computed tomography (CECT) in target volume delineation and investigate their impacts on radiotherapy planning.
Eighteen patients were subjected to F- FDG PET-CT and CECT in the same position. Subsequently, the target volumes were separately delineated on both image sets. In addition, the normal organ doses were compared and evaluated.
The comparison of the primary gross tumour volume (GTV) between the F-FDG PET-CT and CECT imaging revealed that 88.9% (16/18) of the patients had a quantitative change on the F-FDG PET-CT. Out of these patients, 77% (14/18) of the cases had a decrease in volume, while 11% (2/18) of them had an increase in volume on the F-FDG PET-CT. Additionally, 44.4% (8/18) of the patients showed a decrease by > 50 cm on the F-FDG PET-CT. The comparison of the GTV lymph node between the F-FDG PET-CT and CECT revealed that the volume changed in 89% (16/18) of the patients: it decreased and increased in 50% (9/18) and 39% (7/18) on the F-FDG PET-CT. New nodes were identified in 27% (5/18) of the patients on the F-FDG PET-CT. The decrease in the GTV lymph node on the F-FDG PET-CT was statistically significant. The decreased target volumes made radiotherapy planning easier with improved sparing of normal tissues.
GTV may either increase or decrease with the F-FDG PET-CT, compared to the CECT. However, the F-FDG PET-CT-based contouring facilitates the accurate delineation of tumour volumes, especially at margins, and detection of new lymph node volumes. The non-FDG avid nodes can be omitted to avoid elective nodal irradiation, which can spare the organs at risk and improve accurate staging and treatment.
F-氟脱氧葡萄糖正电子发射断层扫描/计算机断层扫描（F-FDG PET-CT）是一种广泛应用且成熟的肺癌分期技术。放射治疗需要精确勾画靶区体积，但在大多数情况下，由于并存肺不张，这一过程较为困难。本研究旨在比较F-FDG PET-CT与增强计算机断层扫描（CECT）在靶区体积勾画方面的差异，并研究它们对放射治疗计划的影响。
18例患者在相同位置接受F-FDG PET-CT和CECT检查。随后，在两组图像上分别勾画靶区体积。此外，对正常器官剂量进行比较和评估。
F-FDG PET-CT与CECT成像对原发性大体肿瘤体积（GTV）的比较显示，88.9%（16/18）的患者在F-FDG PET-CT上有定量变化。在这些患者中，77%（14/18）的病例体积减小，而11%（2/18）的病例在F-FDG PET-CT上体积增大。此外，44.4%（8/18）的患者在F-FDG PET-CT上显示体积减小>50 cm³。F-FDG PET-CT与CECT对GTV淋巴结的比较显示，89%（16/18）的患者体积发生变化：在F-FDG PET-CT上，50%（9/18）的患者体积减小，39%（7/18）的患者体积增大。在F-FDG PET-CT上，27%（5/18）的患者发现了新的淋巴结。F-FDG PET-CT上GTV淋巴结的减小具有统计学意义。靶区体积的减小使放射治疗计划更容易，同时更好地保护了正常组织。
与CECT相比，F-FDG PET-CT检查时GTV可能增大或减小。然而，基于F-FDG PET-CT的轮廓勾画有助于准确勾画肿瘤体积，尤其是在边缘，并能检测出新的淋巴结体积。可以省略不摄取FDG的淋巴结，以避免选择性淋巴结照射，从而保护危险器官，提高准确分期和治疗效果。
