Diagnostic Significance of FDG PET/CT Dynamic Imaging in Detecting Metastatic Lymph Nodes With Papillary Thyroid Cancer.
Diagnostic Significance of FDG PET/CT Dynamic Imaging in Detecting Metastatic Lymph Nodes With Papillary Thyroid Cancer.
The aim of this study is to make up for the gap by performing a dynamic scan of
 <Sup>18<Sup>F-FDG PET/CT on newly diagnosed patients with papillary thyroid carcinoma.
 Pathological and genomic studies are performed. The differences between metastatic central
 lymph nodes images and tissues are compared at the same time. <Sup>18<Sup>F-FDG PET/CT
 dynamic imaging is explored in metastatic central lymph nodes with papillary thyroid cancer
 for the diagnostic value.
Thyroid cancer is the most common malignant tumor in human endocrine system, accounting for
 0.2% ~ 1.0% of malignant tumors .According to the global cancer report released by the world
 health organization (WHO) in 2014, 50% of the new cases of thyroid cancer are papillary
 thyroid cancer (PTC). In recent years, the incidence of thyroid cancer in China shows an
 increasing trend, especially the composition ratio of thyroid micro-papillary carcinoma with
 the focal diameter <1 cm increases rapidly.Although PTC has a good prognosis, according to a
 Meta analysis , PTC lymph node metastasis rate is as high as 28.0%.The central lymph node is
 the most common metastatic site of papillary thyroid carcinoma.In addition, it has been
 reported in literature that lymph nodes in the central region are the first stop of thyroid
 papillary carcinoma metastasis (i.e., sentinel lymph nodes), and lymph nodes metastatic to
 this point are prone to infringe the peripheral esophagus, trachea and recurrent laryngeal
 nerve at an early stage.A large number of clinical cases have confirmed that lymph node
 metastasis of thyroid cancer significantly increases the local recurrence rate after
 surgery.More studies have shown that regional lymph node metastasis increases
 mortality.Therefore, the treatment of lymph node metastasis should not be ignored in PTC
 patients.However, at present, preoperative imaging has certain limitations in the judgment of
 lymph node metastasis in the central region : ultrasound has advantages in the judgment of
 lymph node metastasis in the peripheral group, but poor display in the central group.Although
 MRI scan of head and neck can be multi-directional and multi-sequence imaging, and the
 resolution of soft tissue is high, it is not good at showing calcification.Conventional CT
 alone based on lymph node morphology to determine metastasis also has some
 limitations;Positron emission tomography (PET) sensitivity was < 40%.Although one study
 showed that the probability of non-missed diagnosis of lymph nodes in central PTC region by
 thin slice CT scan was 100%, the specificity was low and the study was
 retrospective.Therefore, b-ultrasound, MRI, CT, PET and other auxiliary examinations have not
 been able to effectively detect all central metastatic lymph nodes before surgery.For
 management of cervical lymph nodes ,2015 American Thyroid Association（ATA） guidelines show
 that thyroid+therapeutic Ⅵ area lymph node dissection should be undertaken if in central or
 lateral lymph nodes are involved.Chinese guidelines recommend that, in order to avoid
 operative complications as far as possible (i.e. effective retainment of the parathyroid
 gland and recurrent laryngeal nerve), regardless of the size of the primary thyroid lesion,
 lymph node dissection in the central area on the same side of the lesion should be performed
 at least.However, in 2017, the second edition of National Comprehensive Cancer Network(NCCN)
 thyroid tumor guidelines believed that if lymph nodes in the central region were negative,
 preventive central region lymph node dissection was not recommended.Above all，there is so
 much controversy over lymph node dissection in the central region. Therefore，it is of great
 significance to effectively evaluate the preoperative lymph nodes station in the central
 region of thyroid papillary carcinoma.

 Early dynamic imaging examination of <Sup>18<Sup>F-FDG PET/CT can be defined as a imaging
 method to detect the status of radioactive tracer (<Sup>18<Sup>F-FDG) which travels with the
 blood flow and is continuously absorbed and excreted by organs (or diseased) tissues after
 being introduced into the body in the early stage.This development reflects the change of
 <Sup>18<Sup>F-FDG activity with time in the early stage of entering the body, and can provide
 information about the dynamic change of tracer metabolism and distribution in tissues with
 time, so that it can provide more metabolic and distribution details of tumor lesions and
 metastatic lesions than static scanning.At present, many studies have shown that
 <Sup>18<Sup>F-FDG PET/CT early dynamic imaging technology can effectively improve the
 sensitivity of hepatocellular carcinoma ,renal cell carcinoma and other tumors.More
 amazing，there may be more advantages in evaluating lymph node metastasis.The blood supply of
 lymph nodes metastatic of thyroid papillary carcinoma is abundant, which helps to locate the
 metastatic tumor lymph node.However，there is no relevant study.Now , investigators plan to
 observe the significance of the method to evaluate the central lymph node metastasis in
 thyroid papillary carcinoma as well as the intrinsic correlations between the significance
 and postoperative pathological results ,which may help to develop surgical strategy by
 preoperative evaluation and avoiding additional dissection.
Inclusion Criteria:

 -  • Accurately diagnosing primary papillary thyroid cancer according to pathological
 diagnostic criteria .

 -  Thyroid papillary carcinoma was suspected by thyroid ultrasound text and/or neck
 CT.

 -  The age is more than 18 years old and less than 65 years old. There is no gender
 restriction.

 -  Untreated patients who have not received surgery, interventional
 therapy,chemotherapy, biotherapy, and radiation therapy.

 -  Physical condition score of Eastern Cooperative Oncology Group（ECOG）: 0-2; no
 major organ dysfunction; oxygen partial pressure ≥ 10.64 kilopascal（kPa）; white
 blood cell count≥ 4 × 109/L; hemoglobin≥ 9.5g/dL; neutrophil absolute count ≥ 1.5
 × 109 / L; platelet count ≥ 100× 109 / L; total bilirubin ≤ 1.5 times of the
 upper limit of normal value;creatinine ≤ 1.25 times of the upper limit of normal
 value; and creatinine clearance ≥ 60ml / min.

 -  Be able to obtain complete follow-up information, understand the situation of
 this study and sign informed consent.

 Exclusion Criteria:

 -  • Poorly controlled diabetics (fasting blood glucose levels > 200 mg/dL).• In addition
 to four types of malignant tumors that can be treated with radical resection, such as
 cervical cancer in situ, basal or squamous cell skin cancer, (breast) ductal carcinoma
 in situ, and organ localized prostate cancer, suffering from any other malignant
 tumors within 5 years.• Breastfeeding and/or pregnant women.

 -  Patients with severe bleeding tendencies (prothrombin time less than 50%,cannot
 be corrected by treatment with vitamin K, etc.).

 -  Recent severe hemoptysis, severe cough, dyspnea or patients are not able to
 cooperate.

 -  People with severe emphysema, pulmonary congestion, and pulmonary heart disease.

 -  Researchers believe that the subject may not be able to complete this study or
 may not be able to comply with the requirements of this study (for management
 reasons or other reasons).