The Correlation Research Of¹⁸F-FDG PET-CT With Sentinel Lymph Nodes In Peripheral Non-small Cell Lung Cancer

BACKGROUND AND OBJECTIVE: Current basic principle of non-small cell cancer(NSCLC) surgical practice involves lung tumor complete resection and standard systemicmediastinal node dissection. Mediastinal lymph node dissection (MLND) mainly consist ofmediastinal lymph node sampling and complete mediastinal lymph node dissection(CMLND), the former perform definite dissection according to the lymph node metastaticpattern, the latter perform the dissection including mediastinal lymph node andsurrounding fat tissue. The complication and mortality caused by CMLND are relativelyincreasing because of the dissection scope expand and operation damage increase thatfollows. However, although the CMLND has been classified as NSCLC radical systemicstandard surgical practice, the debate about the scope and the way of mediastinal lymphnode dissection still exists in clinal practice currently. Thus far, to explore the new precisetechnique of diagonsing lymph node metastasis has been recent research priorities. Thisresearch depends on both the18F-FDG PET-CT imaging and sentinel lymph node (SLN)mapping techniques, its purposes are to analyze the sensitivity, specificity and accuracy aswell as the correlation of lymph nodes diagonsed by18FDG-PET-CT and SLNs detectedusing blue dyes in lymph node metastasis of peripheral NSCLC, also to investigate theapplication value of PET-CT and SLN on evaluating the lymph node metastasis in lungcancer as well as its influence on mediastinal lymph nodes dissction．METHODS: In this prospective study, sixty patients with resectable suspected NSCLCin department of thoracic surgical in Shandong Cancer Hospital were randomized selected from Jul,2009through Jun,2011．All patients underwent integrated PET-CT scanningbefore surgery for lymph node staging．The first lymph nodes staining blue with oleophilicisosulfan blue dye was defined as SLN, and were sent separately for fast-frozen pathologyexamination at thoracotomy. Then all the Non-Sentinel Lymph Node (Non-SLN）detectedintraoperative were also sent for hematoxylin-eosin stain． If required,immunohistochemically examination was used after pneumectomy. Pathologic diagnosiswas the gold standard for comparing PET-CT with SLN．RESULTS:1. PET-CT altered clinical staging in11(18.3%) patients, of which7caseswere upstaged and4cases were downstaged, the treatment planning of7(11.6%) patientshad been changed. Of the60patients with lobectomy of lung,47cases had pathologicstaging coincidence with PET-CT preoperative imaging staging. Two of60patientsprovided a false-negative rate of3.3%, the specificity and accuracy rate of PET-CT stagingwas94.1%and78.3%, respectively.2. At thoracotomy，thirty-seven of60peripheral NSCLC patients injected with isosulfanblue dye had SLNs successful identified. Adenocarcinoma was present in23patients as themost prevalent cell type, squamous cell tumors were diagnosed in9patients,5patientswere confirmed to be other pathologic types. The detection rate of SLN was61.7%(37/60).Of the eighty-five blue-stained SLNs that were resected, fifty-two SLNs in18cases wereproved negative，while15of18patients were preoperative diagnosed N0by PET-CT，fourpatients had only Non-Sentinel Lymph Node (Non-SLN) metastasis. Thirty–three SLNs in19cases were proved positive，while19patients including25SLNs were preoperativediagnosed positive by PET-CT. The sensitivity，specificity，positive predictive value(PPV)，negative predictive value (NPV) and coincidence rate of PET-CT for SLNdiagnosis was78.9%（15/19），83.3%(15/18),83.3%(15/18)，78.9%(15/19)，and81.1%(30/37), respectively．3. Of the37patients with sentinel nodal stations successful identified,18cases werepreooperative diagnosed N0according to PET-CT,31SLNs (mean1.7/patient) weredissected with8contained occult metastases,195Non-SLNs were dissected with17 contained occult metastases. The occult metastatic rate presenting in SLNs wassignificantly higher than that in Non-SLNs(P＜0.05).CONCLUSIONS： Integrated PET-CT diagnosised SLN quite precisely. PET-CTshowed high coincidence rate for clinical staging and postoperative pathologic staging inNSCLC. Combined PET-CT and SLN procedure facilitated the precise estimation oflocalized lymph node involved and the determination of relevant pattern oflymphadenectomy in NSCLC patients, thus, it makes an important influence for both theprognosis of patients and the postoperative treatment modalities.