Comparison of SUV of NSCLC in FDG-PET/CT Attenuation Correction by Average CT and Helical CT

The treatment outcome of non-small-cell lung cancer (NSCLC) patients remains poor despite of the development of target therapy. For NSCLC, it has become an important issue to early detection, correctly staging and treatment planning (including chemotherapy and radiotherapy) as well as simultaneously monitoring the therapy response. Recently, due to the development of positron emission tomography (PET), the standard uptake values (SUV) of [18F] fluorodeoxyglucose (FDG) has been used in functional interpretation of tumors, which including monitoring the tumor response during radiotherapy, and after chemoradiotherapy in NSCLC patients. In addition, pathological response as well as patients overall survivals were also correlated with changes of the FDG uptake. The fundamental of those studies is to measure SUV accurately; however, there will be still some limitations. Nowadays, helical CT (HCT) has replaced traditional Ga-68 transmission rod sources to obtain attenuation map for the PET emission data. The combination of PET and HCT provided a fusion of functional and anatomic images to better localized lesions. Unfortunately, the difference in temporal resolution of PET and HCT may lead to misregistrattion that causes underestimated of SUV. It is especially worsened in the thoracic region, such as in the state of NSCLC, where diaphragm motions continually. In 2006, average CT (ACT) was developed and has been used in PET/CT for better match the temporal resolution of PET images and thus reduces image artifact. Most of those studies focused on heart evaluation, where motions severest, and from those data, ACT seemed to work well. Therefore, it is reasonable to propose the use of ACT in lung regions, where motion less severe than heart. Even now, large clinical data using PET/ACT in cancer patients will be unavailable. In this prospective study, we want to survey the SUV changes and the degree of misregistration of lung lesions in NSCLC using PET attenuation correction with HCT and ACT, respectively. The aims of this prospective study are three. One is to compare the accuracy of coregistration of lung lesions in NSCLC using PET attenuation correction with HCT and ACT. The other is to compare the SUVmax of lung lesions in NSCLC using PET attenuation correction with HCT and ACT. Another is to compare the GTV, CTV, PTV in PET attenuation correction with HCT vs. attenuation correction with ACT. The outcomes will be evaluated with (1) the accuracy of coregistration at primary tumor and regional lymph nodes when using PET attenuation correction with HCT vs. attenuation correction with ACT; (2) the differences of SUVmax value at primary tumor and regional lymph nodes as the prognosticators when using PET attenuation correction with HCT vs. attenuation correction with ACT; (3) the differences of GTV, CTV, PTV at primary tumor and regional lymph nodes when PET attenuation correction with HCT vs. attenuation correction with ACT.

Project ID:PC9902-0529
External Project ID:NSC97-2314-B182-041-MY3