Clinical Application Of¹⁸F-FDG PET/CT Combined With Contrast-enhanced CT For Assessing The Respectability Of Pancreatic Cancer

[Objective]To explore the value of F-FDG PET/CT combined with enhanced CT in assessing the respectability of pancreatic cancer.[Materials and Methods]1. object of study1.1Case inclusion criteria①Patients diagnosis for pancreatic cancer clinical, Eventually confirmed by pathology or clinical follow-up②Patients have18F-FDG PET/CT scan and enhanced CT scan at the same machine in our PET center line③The time between18F-FDG PET/CT examination and operation is in2-14days④All patients have integrited clinical datas1.2Case exclusion criteria①Patients not suitable for surgery because of cardiopulmonary dysfunction②Patients not suitable for surgery because of other complications③Patients with advanced age can not be tolerated by the surgeon 2. Basic InformationThere are85cases of pancreatic cancer patients in our hospital from April2008to August2012underwent18F-FDG PET/CT scan and at the same machine and the same time have abdominal contrast enhanced CT scan, including46males and39females, the age is range from35to90, with an average age63.2±12.6.analysis the18F-FDG PET/CT and enhanced CT imaging CT data of patients with pancreatic cacer restrospectively.all the patients were comformed by biopsy,intraoperativer findings,or clinical follow-up.3. Equipment and enhanced with contrast agent RDS1111Medical cyclotron, Somatom Sensation Biography16PET/CT Machine Equipped with16-slice spiral CT(SIEMENS, Germany), Non-ionic contrast medium iohexol,(United States) High-pressure syringe(Ulrich XD2001, Ulrich Company, Germany)18F-deoxyglucose (18F-FDG), Produced by the Guangdong Provincial People’s Hospital PET Center RDS1111medical cyclotron, Radiochemical purity greater than95%, After rigorous testing of sterile, non-pyrogenic, endotoxin4. Inspection methods4.1Preparation of patients with imaging①Avoid strenuous exercise within24hours before the test②Fasted for more than6hours (Appointment morning check do not eat breakfast, afternoon check do not eat lunch)③Detect blood sugar with a blood glucose test strips within the scope of80～150mg/dl,when blood sugar is higer than150mg/dl, should try to re-arrange the patient examination time If conditions permit, if patients need insulin hypoglycemic, we should extended four hours for injection of18F-FDG.④Intravenous18F-FDG state of calm under the back of the hand, The injected dose of0.14-0.22mCi/kg⑤After injection of18F-FDG, Supine rest for45-60minutes in a light and dark, quiet, warm room, with lying or Supine, as try to relax, to mover less and less talk⑥Drinking water1500ml before imaging acqusition, the imaging before Zhu Huanzhe urine.4.2Imaging methodsPatients take the supine, CT positioning lights to determine scan initiation site, have a Do low dose (50mA,120kV) X-ray sweep, and Determine the scanning range. Low-dose CT scan in quiet breathing, Imaging range is from the thigh to the base of the skull, First have a conventional low-dose CT scan,and then beds line the same range of PET image acquisition.PET acquisition generally6～8beds, Each bed acquisition time of2minutes. After the acquisiti complete, use the CT data for attenuation correction of PET images. Acquisition process patients maintain calm breathing and1keep postura unchanged.In order to keep an exact match to ensure that CT and PET image fusion. The brain PET acquisition, skull mild backwards, the scope of the skull base to the occipital punch,1beds, acquisition time5minutes. Patients will have3-hour delayed scan when necessary. Early imaging is after intravenous injection of18F-FDG60±5minutes, Delayed imaging is for2.5-3hours after the intravenous injection of18F-FDG。The delayed imaging acquisition conditions must be consistent with the earlier acquisition conditions.After PET scan complete, intravenous injection of non-ionic contrast medium iohexol(General Electric Company, United States), Concentration300mg I/ml, Dose1.5-2.0ml/kg, Injection flow rate of3ml/s, High pressure injection syringe(Ulrich XD2001, Ulrich Company, Germany).25～30s arterial phase scan,40～45s pancreatic phase scan, and65～70s liver phase scan after contrast injection. Scanning parameters:artery120kv,250mAs, Pancreatic phase of120kv,250mAs, venous phase120kv,200mAs. The width of the collimator is0.75mm. Thickness of5mm,and image reconstruction slice thickness1.5mm.5. Image reconstruction and fusionThe body portion and brain scan all of the data transmitted to the Wizard workstation for fusion. obtain the PET, enhanced CT and PET/CT fusion image of coronal, sagittal, and cross-sectional. Enhanced CT data using standard reconstruction method, matrix512×512, the skull reconstruction slice thickness5mm, the chest lung window reconstruction thickness of1mm, abdomen, chest and mediastinal window reconstruction thickness of1.5mm.6. Image AnalysisPET/CT image Analysis:The body portion and brain scan all of the data transmitted to the Wizard workstation for fusion. obtain the PET, enhanced CT and PET/CT fusion image of coronal, sagittal, and cross-sectional. PET images is mainly used for qualitative diagnosis of the lesion and looking distant metastases. Observed various organs of the body whether there is a lesion18F-FDG uptake increased. Degrees of18F-FDG uptake of in PET images indicates whether a lesions is benign and malignant. We use liver as a reference organ, Semi-quantitative criteria, determination of pancreatic tumor SUV (standardized uptake value), Standard uptake value is a semi-quantitative evaluation of tumor tissue most commonly used indicators of the degree of glucose metabolism.Enhanced CT image analysis:Put diagnostic CT and enhanced CT scan data transmission to Esoft workstation. Enhanced CT images mainly used to observe the lesion location, density,and arterial phase, pancreatic phase, liver tumors and normal pancreas density after contrast enhanced,and Measurement of lesion size, intra-abdominal lymph node size. Assessment of the surrounding tissue organ invasion situation. Peripancreatic vascular morphology, walk the line, pipe diameter, strengthen performance, the The relationship between Surrounding fat fat and lumps. The peripancreatic vascular include:the hepatic artery, celiac axis, superior mesenteric artery, portal vein, superior mesenteric vein, Splenic artery, splenic vein is not included.because it can removed together with the spleen。 Metastases diagnostic criteria:The lesions radioactive concentration is higher than the surrounding normal tissue on18F-FDG PET/CT imaging and there Enlarged lymph nodes on the CT imaging in the corresponding parts, or abnormal density mass in distant tissues and organs.(1) Visual Qualitative analysis:①PET imaging indicates the lesion radiotracer uptake is higher than the surrounding normal tissues, CT scan shows the corresponding parts of the anomalous density shadow or abnormal enhancement stove, we consider for metastases.②The short diameter of lymph node is greater than1cm on CT imaging and/or lymph node radioactivity uptake is higher than the surrounding normal tissue on PET imaging, we considered as a metastatic lymph node(2) Semi-quantitative analysis:Outline the region of interest (ROI) in the18F-FDG PET images, that means To outline lesions radioactive uptake area (such as lesions without apparent uptake position shown in the sketch CT lesion location). SUV is automatically calculated by the computer program to obtain. because the SUV average (SUVmean) by lesion morphology, human operating factors, we take the maximum standardized uptake value (SUVmax) as analytical indicators.Finally, according to the18F-FDG PET/CT imaging findings of a comprehensive analysis to determine the diagnosis and evaluation of resectability of pancreatic cancer line., film-reading By at least three physicians have experience in nuclear medicine and radiology,and then have the same idea for evaluation of resectability.Adenocarcinoma unresectable criteria:①have distant metastasis;②lymph node metastasis outside the peripancreatic area;③Adjacent organs or tissue infiltration(Except the stomach, duodenum, common bile duct, and spleen because it can removed together with the lump);④The peripancreatic arterial or venous violations(arterial or venous violations of the grading criteria is in Table1, Table2). Meet more than one of the criteria Above is sentence to unresectable.The standard whether the surgery resection is successfuly:the tumor and surrounding blood vessels or organs mild adhesions separable or has not been exposed to the tumor and surrounding blood vessels or organs, complete resection of the tumor, and surgical margin is negative,.and there is no distant metastasis in the peritoneal cavity.7. statistical treatment7.1Basic Statistical Concepts①sensitivity=true positive cases/(true positive cases+false negative number of cases)②specificity=true negative cases/(number of true-negative cases+false positive number of cases)③The positive predictive value=true positive cases/(number of true positive cases+false positives the number of cases)④negative predictive value=number of true-negative cases/number of cases (true negatives+number of false-negative cases) The⑤accuracy=(true-positive cases+true negative cases)/total number of cases7.2Use Software of SPSS13.0for statistical analysis. Measurement data using the X±S. unresectable As positive, compared the image evaluation and clinical surgery and follow-up results are, pairing material x2test,and then calculate the accuracy, sensitivity and specificity of the preoperative image evaluation. Using two-sample t test, comparing surgical resection group and no resection group for the Standardized uptake values and maximum lesion diameter difference, when P<0.05, shows that there are significant differences in two groups[Results]85patient were included in this study. Occurred in pancreatic head and neck50patients (58.8%) of and, body and tail in30cases (35.3%), involving the whole pancreas in5cases (5.9%). Maximum diameter of tumor is10.7cm×6.7cm, the minimum is0.6cm x0.6cm. SUVmax of the tumor is range from1.7to35.5, average SUVmax is:6.9±4.7.Preoperative18F-FDG PET/CT and enhanced CT to determine resectability27cases, unresectable58cases of.36patients with unresectable for distant metastasis alone,5patients with unresectable peripancreatic vascular invasion alone,17cases appear peripancreatic vascular assault and metastasis or infiltration of adjacent organs at the same time,among them including:Celiac7cases, the hepatic artery4cases,5cases of superior mesenteric artery,9cases of superior mesenteric vein, portal vein8t cases, three cases have the adjacent organs violation, including:the left kidney, left adrenal gland, liver. 27cases of85judged for resectable before surgery (Figure1),unresectable58.36cases of unresectable for distant metastasis alone (Figure2),5cases of unresectable for the peripancreatic vessels violated,17cases of unresectable for peripancreatic vascular invasion and metastasis or infiltration of adjacent organs (Table6).In85patients with clinical stage, the Ⅰ A stage is6, the Ⅰ B stage15,Ⅱ A stage is5cases, Ⅲ stage is5cases, Ⅳ stage is48cases.28cases in85patients with surgical resection mainly Ⅰ A, Ⅰ B period, a few Ⅱ A the Ⅱ B patients with resectable (Table7).35cases of the85patients have surgery therapies in14days afterContrast enhanced18F-FDG PET/CT scan.28of them were successfully underwent radical surgery. Including Pancreaticoduodenectomy (21cases, picture6), expand pancreaticoduodenal radical surgery (n=2, picture), pancreatic body and tail combined with spleen resection (n=5, Figure2). Another7cases cholecystectomy-cholangioenterostomy on palliative surgery. One unresectable case make a mistake as resectable (picture3), The results showed that can not be separated for severe abdominal adhesions after laparotomy and turn to palliative surgery. Two cases mistaken as unresectable,and one case for superior mesenteric vein initial segment of the right edge of the portal vein mass surrounding local luminal narrowing, Another example of the tumor and the superior mesenteric vein exposure to2/3of the circumference. But successfully isolated the tumor cells and vascular after Laparotomy. Underwent the pancreaticoduodenal radical surgery and to expand pancreaticoduodenal radical surgery Respectively.There are28patients have Successful radical radical surgery in all.In the28surgically resected patients,22cases in the pancreatic head (78.6%),6cases in the body and tail of pancreas(21.4%). In this study, resection rate is 46%of pancreatic cancer in head and16.7%of pancreatic cancer resection rate in the body and tail of pancreas, but for patients involving the full pancreatic cancer the resectability rate is0%.There seven cases that the maximum diameter of the tumor cross-section is less than2cm,and5patients of them underwent surgical resection. There35patients that the maximum diameter of the tumor cross-section is range from2cm to4cm, and5patients of them underwent surgical resection. There43patients that the maximum diameter of the tumor cross-section is larger than4cm, and only5patients of them underwent surgical resection. The largest diameter of the tumor cross-section is5.3cm in the28surgically resected patients,and Minimum diameter of the tumor cross-section is1.1cm, anaverage diameter of the tumor cross-section is2.9±1.0cm. The largest diameter of the tumor cross-section is17.2cm in the57unresected patients,and Minimum diameter of the tumor cross-section is0.6cm, anaverage diameter of the tumor cross-section is5.1±2.5cm. The SUVmax average of surgical resection group and unresected group values were5.5±3.5,7.5±5.1respectively, P=0.481(>0.05), The SUVmax of the Surgical resection group and the unresected group was no significant difference. The average of maximum diameter of the tumor cross-section of Surgical resection group and unresected group were3.0±1.0cm and5.0±2.5cm resepectively, P=0.011(<0.05), that means the maximum diameter of the tumor cross-section between the surgical resection group and no resection group are significant differences. The maximum diameter of the unresected tumor group was significantly larger than the surgical resection group, there are some direct or indirect correlation in maximum diameter of tumor cross-section and resection rate.Thr average SUVmax for surgical resection group with unresectable group is5.52±3.45and7.56±5.10respectively, statistical analysis indicates the difference was statistically significant between surgical resection group with unresectable group (P<0.001); the average diameter of tumor for surgical resection group with unresectable group is2.96±1.04,5.08±2.48, the statistical analysis indicates that the difference was statistically significant between the surgical resection group with unresectable group (P<0.001)(Table8). The maximum diameter of the tumor and the SUVmax of unresectable group are significantly greater than the surgical resection group, tumor cross the maximum diameter and the SUVmax with surgical resection rate of certain direct or indirect correlation.18F-FDG PET/CT detect distant metastasis fo organs or lymph node a total of48cases in the85patients, including38cases of liver metastases,9cases of peritoneal metastasis,5cases of bone metastasis,5cases of lung metastasis, five cases have extensive metastasis.25cases of distant lymph node metastasis.Take the results of Pathology, clinical surgery and follow-up co nfirmed as standard, the sensitivity, specificity, positive predictive value, negative predictive value of the pancreatic cancer unresectable evaluation determined by18F-FDG PET/CT combind with enhanced CT is98.2%(56/57),92.9%(26/28),96.6%(56/58),96.3%(26/27). the accuracy of pancreatic cancer Resectability evaluation before surgery judged by18F-FDG PET/CT is96.5%(82/85), P=0.87. Preoperative evaluation of resectability of pancreatic cancer two cases of false-positive, one cases of false negative. There is no significant difference in contrast-enhanced F-FDG PET/CT preoperative evaluation and the results of clinical surgery. Preoperative evaluation of resectability of pancreatic cancer two cases of false-positive rate, false negative cases..18F-FDG PET/CT joint control enhanced CT the preoperative judgment and clinical surgery and follow-up results (Table9).[Conclusion]The use of18F-FDG PET/CT combined with enhanced CT for assessing the respectability of pancreatic cancer is feasible and accurate. (1) The evaluation of local infiltration:contrast enhanced CT scan can show the peripancreatic vessels clearly, and is sensitive to the peripancreatic vascular invasion.(2) The evaluation of distant metastasis:pancreatic cancer have distant metastasis is very early, the whole body of18F-FDG PET image is sensitively in the detect the distant metastases and is superior to conventional imaging methods.