Significance of SUV on Follow-up F-18 FDG PET at the Anastomotic Site of Gastroduodenostomy after Distal Subtotal Gastrectomy in Patients with Gastric Cancer

68Ga-FAPI-04 PET for Surveillance of Anastomotic Recurrence in Postoperative Patients with Gastrointestinal Cancer: a Comparative Study with 18F-FDG PET

PURPOSE

This study aims to compare the diagnostic efficacy of 68Ga-FAPI-04 PET and 18F-FDG PET for detecting anastomotic recurrence in postoperative patients with gastrointestinal cancer, and to characterize the signal pattern over time at surgical wounds on both PET imaging.

METHODS

Gastrointestinal cancer patients who planned to 68Ga-FAPI-04 and 18F-FDG PET/CT imaging for postoperative surveillance were involved. The SUVmax at surgical wounds were assessed. Endoscopic pathology confirmed anastomotic recurrence or it was ruled out by imaging and clinical follow-up. The sensitivity, specificity, positive and negative predictive values (PPV and NPV), and accuracy of the two PET imaging in detecting anastomotic recurrence were compared. Relationships between tracer uptake at surgical wounds and postoperative time were also analyzed.

RESULTS

Compared with non-recurrent patients, the recurrent patients exhibited a significantly higher anastomotic SUVmax on 68Ga-FAPI-04 PET (SUVmax: 9.92 ± 4.36 vs. 2.81 ± 1.86, P = 0.002). Sensitivity, specificity, PPV, NPV, and accuracy of detecting anastomotic recurrence were 100.0%, 87.3%, 41.7%, 100.0%, and 88.3% for 68Ga-FAPI-04 PET, and 60.0%, 81.8%, 23.1%, 95.7%, and 80.0% for 18F-FDG PET, respectively. Although 68Ga-FAPI-04 PET signal at surgical wounds showed a slight trend to decrease with time, no statistical difference was observed over months post-surgery (P > 0.05).

CONCLUSIONS

Both tracers displayed high NPVs in identifying anastomotic recurrence with a higher sensitivity to 68Ga-FAPI-04. Tracer uptake at anastomotic sites does not decrease significantly over time, which results in low PPVs for both PET. Therefore, it is difficult to differentiate anastomotic recurrence from inflammation on either PET imaging.

PET/Computed Tomography and Precision Medicine: Gastric Cancer

Gastric cancer is a disease with low survival rates and high morbidity, requiring accurate and prompt diagnosis and treatment. Although limited in the evaluation of the primary tumor as such, the metabolic information of primary tumors in an ¹⁸F-FDG PET/CT study can assist in surgical and treatment planning and differentiating gastric cancers. It detects nodal disease with good specificity and positive predictive value, thus enabling appropriate therapy for individual patients. It provides valuable information about distant metastases, altering therapy decisions. It has reasonably good performance in detecting recurrent disease and in the follow-up of patients.

Diagnostic performance of FDG PET/CT for surveillance in asymptomatic gastric cancer patients after curative surgical resection

PURPOSE

The present study evaluated the diagnostic performance of 2-[(18)F] fluoro-2-deoxy-D-glucose (FDG) positron emission tomography/computed tomography (PET/CT) for surveillance in asymptomatic gastric cancer patients after curative surgical resection.

METHODS

We retrospectively recruited 190 gastric cancer patients (115 early gastric cancer patients and 75 advanced gastric cancer patients) who underwent 1-year (91 patients) or 2-year (99 patients) postoperative FDG PET/CT surveillance, along with a routine follow-up program, after curative surgical resection. All enrolled patients were asymptomatic and showed no recurrence on follow-up examinations performed before PET/CT surveillance. All PET/CT images were visually assessed and all abnormal findings on follow-up examinations including FDG PET/CT were confirmed with histopathological diagnosis or clinical follow-up.

RESULTS

During follow-up, 19 patients (10.0 %) developed recurrence. FDG PET/CT showed abnormal findings in 37 patients (19.5 %). Among them, 16 patients (8.4 %) were diagnosed as cancer recurrence. Of 153 patients without abnormal findings on PET/CT, three patients were false-negative and diagnosed as recurrence on other follow-up examinations. The sensitivity, specificity, positive predictive value, and negative predictive value of FDG PET/CT were 84.2 %, 87.7 %, 43.2 %, and 98.0 %, respectively. Among 115 early gastric cancer patients, PET/CT detected recurrence in four patients (3.5 %) and one patient with local recurrence. Among 75 advanced gastric cancer patients, PET/CT detected recurrence in 12 patients (16.0 %), excluding two patients experiencing peritoneal recurrence. In addition, FDG PET/CT detected secondary primary cancer in six (3.2 %) out of all the patients.

CONCLUSIONS

Post-operative FDG PET/CT surveillance showed good diagnostic ability for detecting recurrence in gastric cancer patients. FDG PET/CT could be a useful follow-up modality for gastric cancer patients, especially those with advanced gastric cancer. However, further careful evaluation is needed because of false-positive findings on PET/CT.

[18F]Fluorodeoxyglucose PET/Computed Tomography in Gastrointestinal Malignancies

This article discusses the current state-of-the-art application of 2-deoxy-2-[(18)F]fluoro-d-glucose (FDG)-PET and FDG-PET/computed tomography (CT) in the management of patients with gastrointestinal malignancies. Gastrointestinal malignancies include many different cell types, several common malignancies of which may be imaged by FDG-PET/CT. This review focuses on gastric carcinoma, pancreatic carcinoma, hepatocellular carcinoma, cholangiocarcinoma, colorectal carcinoma, and stroma cell tumors. The role of FDG-PET/CT in staging these malignancies is discussed, in addition to (re)staging, detection of recurrent disease, patient selection/prognostication, and response assessment, using the currently available literature.

Performance of (18)F-FDG PET/CT as a postoperative surveillance imaging modality for asymptomatic advanced gastric cancer patients

OBJECTIVE

The purpose of this study was to investigate the diagnostic performance of postoperative fluorine-18 fluoro-2-deoxy-D-glucose ((18)F-FDG) positron emission tomography/computed tomography (PET/CT) as a surveillance modality for advanced gastric cancer patients who were asymptomatic and negative by conventional follow-up.

METHODS

We retrospectively collected 46 advanced gastric cancer patients who received approximately 1-year-postoperative (18)F-FDG PET/CT surveillance following curative resection (mean age 60.6 ± 11.5 years). (18)F-FDG PET/CT was interpreted by nuclear medicine physicians who were blind to the clinical information. Final confirmation was determined by clinical follow-up using tumor markers, conventional CT scan, upper gastrointestinal endoscopy and with/without subsequent histopathologic diagnosis.

RESULTS

Four patients developed recurrence (8.7 %; 1 local and 3 distant recurrences). For local recurrence, (18)F-FDG PET/CT found four hypermetabolic lesions and one was local recurrence. For distant recurrence, seven hypermetabolic lesions were found in six patients and true-positive was three lesions. False-positive cases were mainly turned out to be physiologic small bowel uptake. Regardless of the recurrence site, the sensitivity, specificity, positive predictive value and negative predictive value of (18)F-FDG PET/CT were 100 % (4/4, 95 % confidence interval (CI) 39.6-100 %), 88.1 % (37/42, 95 % CI 73.6-95.5 %), 44.4 % (4/9, 95 % CI 15.3-77.3 %) and 100 % (37/37, 95 % CI 88.3-100 %), respectively in the patient-based analysis.

CONCLUSION

Our study showed good specificity of postoperative surveillance (18)F-FDG PET/CT for detecting recurrence. Careful caution should be made for interpreting some false-positive hypermetabolic lesions in postoperative (18)F-FDG PET/CT, especially at the local anastomosis site.

Predictive value of volumetric parameters measured by F-18 FDG PET/CT for lymph node status in patients with surgically resected rectal cancer

OBJECTIVE

The objective of this study was to investigate the predictive role of volumetric parameters such as metabolic tumor volume (MTV) and total lesion glycolysis (TLG) measured by F-18 FDG PET/CT for regional lymph node (rLN) metastasis in rectal cancer patients.

METHODS

Retrospectively, 74 rectal cancer patients were enrolled. All patients received surgical treatment and F-18 FDG PET/CT at diagnosis. The F-18 FDG PET/CT findings of primary cancer and rLN involvement were compared with the pathologic diagnosis within 5 weeks after operation. Univariate and multivariate analyses were used to analyze the associations among the pathologic LN status and age, sex, T stage, AJCC stage, SUVmax, lymphatic invasion, venous invasion, neural invasion, and volumetric parameters.

RESULTS

The LN (+) group showed statistically significant higher values of MTV2.5 (p < 0.0001), MTV3 (p < 0.0001), MTV3.5 (p = 0.0001), TLG2.5 (p = 0.0007), TLG3 (p = 0.0011), and TLG3.5 (p = 0.0024). In univariate analysis, T stage, AJCC stage, neural invasion, and volumetric parameters were factors significantly associated with pathologic LN involvement. However, in multivariate analysis, advanced T stage, high AJCC stage, MTV2.5, and TLG2.5 were associated with pathologic LN involvement in rectal cancer.

CONCLUSION

This study showed that, not only T stage and AJCC stage, but also volumetric parameters such as MTV2.5 and TLG2.5 are useful factors for the prediction of pathologic LN status in rectal cancer patients.