Role of 18F-fluoro-2-deoxyglucose Positron Emission Tomography in Gastric GIST: Predicting Malignant Potential Pre-operatively

Abstract

PurposeIt is difficult to obtain biopsies from gastrointestinal stromal tumors (GISTs) prior to surgery because GISTs are submucoal tumors, despite being the most common nonepithelial neoplasms of the gastrointestinal tract. Unlike anatomic imaging techniques, PET-CT, which is a molecular imaging tool, can be a useful technique for assessing tumor activity and predicting the malignant potential of certain tumors. Thus, we aimed to evaluate the usefulness of PET-CT as a pre-operative prognostic factor for GISTs by analyzing the correlation between the existing post-operative prognostic factors and the maximum SUV uptake (SUVmax) of pre-operative 18F-fluoro-2-deoxyglucose (FDG) PET-CT.Materials and MethodsThe study was conducted on 26 patients who were diagnosed with gastric GISTs and underwent surgery after being examined with pre-operative FDG PET-CT. An analysis of the correlation bewteen (i) NIH risk classfication and the Ki-67 proliferation index, which are post-operative prognostic factors, and (ii) the SUVmax of PET-CT, which is a pre-operative prognostic factor, was performed.ResultsThere were significant correlations between (i) SUVmax and (ii) Ki-67 index, tumor size, mitotic count, and NIH risk group (r=0.854, 0.888, 0.791, and 0.756, respectively). The optimal cut-off value for SUVmax was 3.94 between "low-risk malignancy" and "high-risk malignancy" groups. The sensitivity and specificity of SUVmax for predicting the risk of malignancy were 85.7% and 94.7%, respectively.ConclusionsThe SUVmax of PET-CT is associated with Ki-67 index, tumor size, mitotic count, and NIH classification. Therefore, it is believed that PET-CT is a relatively safe, non-invasive diagnostic tool for assessing malignant potential pre-operatively.

Prognostic Stratification of Metastatic Gastroenteropancreatic Neuroendocrine Neoplasms by 18F-FDG PET: Feasibility of a Metabolic Grading System

“…We aimed to assess the prognostic power of patient stratification in inoperable metastatic disease by 18 F-FDG PET and to compare it with other conventional prognostic variables, including the Ki-67 index; the outcome variable was overall survival in a consecutive patient population with inoperable metastatic disease for which 18 F-FDG PET/CT was implemented in the diagnostic work-up.…”

“…It is conceivable that tumor grading in multifocal metastatic disease may be significantly improved by such a whole-body imaging approach; it would facilitate individualized treatment and allow personalized medicine (10). 18 F-FDG is a radiochemically modified, positron-emitting glucose analog that allows metabolic PET imaging depicting the glycolytic activity of tumors, thus characterizing viability and malignant potential. 18 F-FDG PET imaging has been shown to prognosticate survival in various tumor entities (11,12).…”

“…18 F-FDG is a radiochemically modified, positron-emitting glucose analog that allows metabolic PET imaging depicting the glycolytic activity of tumors, thus characterizing viability and malignant potential. 18 F-FDG PET imaging has been shown to prognosticate survival in various tumor entities (11,12). Especially in tumors with variable 18 F-FDG uptake, such as hepatocellular carcinoma (13,14), prostate cancer (15,16), and gastrointestinal stroma tumors (17,18), a correlation between 18 F-FDG avidity and biologic behavior of the tumor (indicated by patient survival) has been shown to facilitate outcome prediction or metabolic grading by noninvasive measures.…”

Gastrointestinal stromal tumor of the esophagus: current issues of diagnosis, surgery and drug therapy

“…The PET-avidity of benign tumors limits the role of FDG-PET in the differential diagnosis of submucosal tumors of the esophagus. On the other hand, FDG-PET is known to be useful for evaluating postoperative recurrence and the response of GISTs to chemotherapy (1,24,25).…”

“…The maximum standardized uptake value (SUVmax) on FDG-PET is considered to correlate with the degree of malignancy of GIST, but the definitive diagnosis is difficult (1,24,25). Dendy et al reported that esophageal leiomyomas also showed a wide range of SUVmax values, from 3.8 to 13.4 (23).…”