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Objective:To analyze the imaging features of hepatic metastases in gastrointestinal stromal tumors (GIST) on 18F-fluorodexyglucose (FDG) PET/CT in order to improve the accuracy of diagnosis. Methods:Clinical and imaging data of 33 patients (18 males, 15 females, age 34-70 years) with hepatic metastases in GIST who underwent PET/CT examination between May 2013 and July 2019 in Fujian Cancer Hospital were analyzed retrospectively. All patients underwent 18F-FDG PET/CT early imaging, and nine of them underwent delayed imaging. Visual analysis was performed on the PET/CT images by comparing FDG uptake of hepatic lesions and liver background, and all lesions were classified as significant hypermetabolism, slightly higher metabolism and equal or lower metabolism. Maximum standardized uptake value (SUV max) of primary GIST lesions and hepatic metastases were calculated and compared, and the relationship between them was analyzed. Wilcoxon rank sum test and Spearman rank correlation analysis were used to analyze the data. Results:Among 33 GIST patients, 9 patients had solitary hepatic metastasis, and 24 patients had multiple hepatic metastases (104 lesions). The diameter of metastases was 0.8-14.6(2.2(1.5, 3.9)) cm, and SUV max was 1.4-21.5(3.6(2.4, 5.7)). Of the 104 hepatic metastases, 94.2%(98/104) lesions had clear boundaries, 65.4%(68/104) lesions had uniform density (2 lesions with cystic density), 34.6%(36/104) lesions had uneven density in which hemorrhage, cystic change or necrosis could be found. On visual analysis of PET images, 38.5%(40/104) lesions were with significant hypermetabolism, 26.0%(27/104) were with slightly higher metabolism and 35.6%(37/104) were with equal or lower metabolism. In 24 patients with multiple hepatic metastases, 79.2%(19/24) showed different metabolic levels synchronously. Among 67 hypermetabolic metastases, 34.3%(23/67) were with homogeneous metabolism, of which 13 lesions with diameter<2.0 cm; 65.7%(44/67) were with heterogeneous metabolism, of which 36 lesions with diameter≥2.0 cm. There was a moderate correlation of SUV max between GIST primary tumors and hepatic metastases ( n=15; 9.2(6.8, 14.5) vs 3.8(2.1, 6.0), rs=0.556, P<0.01). The difference of SUV max between GIST primary tumors and hepatic metastases was statistically significant ( z=-5.098, P<0.01). In delayed imaging, 13/15 hepatic metastases with equal or lower metabolism changed to slightly higher metabolism. Conclusions:Hepatic metastases in GIST on 18F-FDG PET/CT imaging usually have clear boundary, and often associate with cystic degeneration, hemorrhage or necrosis. The metabolic patterns of hepatic metastases in GIST are varied. Delayed PET/CT imaging is helpful for the diagnosis of hypometabolic hepatic metastases in GIST.
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Objective@#To evaluate the value of 18F-FDG PET-CT in predicting the malignant potential of Gastrointestinal Stromal Tumors (GIST).@*Methods@#The clinical and pathological features of 31 patients with GIST confirmed by surgery or biopsy were retrospectively analyzed. The malignant potential of GIST before treatment was assessed by 18F-FDG PET-CT. The GIST risk classification was graded according to the Standard revised by the National Institutes of Health (NIH) in 2008. The relationship between the maximal standard uptake value (SUVmax) and GIST risk classification, tumor diameter, Ki-67 index, and mitotic count were analyzed respectively. The cut-off level of SUVmax for the diagnosis of malignant GIST was calculated from the Receiver Operating Characteristic (ROC) curve.@*Results@#Among the 31 cases of GIST patients, 14 cases were gastric primary (stomach group) and 17 cases were nongastric primary (outside stomach group). The SUVmax, tumor diameter, Ki-67 index and mitotic count of the 31 patients were 8.21±4.68, (7.82±5.12)cm, (10.03±11.07)% and (12.29±10.55)/50 HPF, respectively. SUVmax was significantly correlated with GIST risk classification (r=0.727, P<0.01), but not with tumor diameter, Ki-67 index and mitotic count (r=0.348, r=0.284, r=0.290, P=0.055, P=0.121, P=0.114). The SUVmax, tumor diameter, Ki-67 index and mitotic count in the stomach group were 4.36±2.36, (6.08±4.31)cm, (3.43±3.03)% and (5.71±2.20)/50 HPF, respectively. SUVmax was significantly correlated with tumor diameter, GIST risk classification and Ki-67 index (r=0.682, r=0.868, r=0.732, P<0.01) but not with mitotic count (r=0.510, P=0.063). The SUVmax of the GIST in the gastric group and the outside gastric group were 4.36±2.36 and 10.68±5.50, respectively. The difference was statistically significant (P=0.001). The SUVmax in the malignant group of GIST (middle or high risk grade) was 8.90±4.89, which was significantly higher than 2.22±0.86 in the benign group (low or very low risk grade). The difference was statistically significant between the two group (P<0.01). ROC curve analysis showed that a SUVmax cut-off of 3.75 was the most sensitive for predicting malignant GIST. When the area under the curve of 0.969, the sensitivity was 84.6% and the specificity was 100%.@*Conclusions@#The SUVmax was strongly correlated with the GIST risk category and also with the tumor diameter and Ki-67 index in the gastric primary GIST, so it can be used as an effective indicator in predicting malignant potential of GIST before treatment.
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Objective To compare the diagnostic values of 18F-FDG and 18F-FLT PET/CT in patients with suspicious recurrence of glioma after multimodal treatment.Methods A total of 20 patients (13 males,7 females;age range:12-73 years) with glioma who underwent 18F-FDG and 18F-FLT PET/CT due to abnormal enhancement on MRI from January 2012 to June 2015 were enrolled in this retrospective study.According to the pathological or follow-up results,patients were divided into therapy-related benign changes (TRBC) group and recurrent glioma group,the later was subdivided into initial low-grade glioma (LGG) group and initial high-grade glioma(HGG) group.T/NT ratios of 18F-FDG and 18F-FLT between HGG (LGG) group and TRBC group were compared using one-way analysis of variance and the least significant difference t test.ROC curve analysis was conducted to calculate the differential diagnostic efficiency of 18F-FDG and 18F-FLT between TRBC and recurrent glioma.Results A total of 14 patients were proved as recurrent glioma and 6 patients as TRBC.The mean 18F-FDG T/NT ratios of HGG group,LGG group and TRBC group were 2.31±0.86,1.32±0.86 and 1.32±0.64,respectively.The 18F-FDG T/NT ratio of the HGG group was significantly higher than that of the TRBC group(F=3.671,t=-2.471,P＜0.05).The mean 18F-FLT T/NT ratios of HGG group,LGG group and TRBC group were 8.94±3.14,7.18±3.29 and 1.92±1.20,respectively (F=13.301,t values:-5.150 and-2.360,both P＜0.05).The optimal T/NT cutoff values for 18 F-FDG and 18F-FLT PET/CT were 1.62 and 4.58,respectively.The sensitivity,specificity and accuracy of detecting recurrent glioma with optimal T/NT cutoff value were 11/14,5/6 and 16/20 for 18F-FDG PET/CT,and those for 18F-FLT PET/CT were 13/14,6/6 and 19/20,respectively.No significant difference was observed between the diagnostic efficiencies of the two imaging modalities (x2 values:1.167,1.091 and 2.057;all P＞0.05).Conclusion There were no statistical significances between 18F-FDG and 18F-FLT PET/CT on the differential diagnosis of glioma recurrence.
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<p><b>OBJECTIVE</b>To explore the preoperative diagnostic value of ¹⁸F-fluorodexyglucose positron emission tomography combined with contrast enhanced computed tomography (¹⁸F-FDG PET-ceCT) in patients with colorectal cancer liver metastasis.</p><p><b>METHODS</b>Clinical and imaging data of 58 patients with suspicious colorectal cancer liver metastasis between April 2010 and March 2013 were retrospectively evaluated. All the patients underwent ¹⁸F-FDG PET-ceCT. On the basis of definitive diagnosis, the sensitivity, specificity, accuracy and consistency of routine PET-CT, ceCT and ¹⁸F-FDG PET-ceCT were calculated.</p><p><b>RESULTS</b>A total of 147 suspicious lesions of colorectal cancer liver metastasis were found in 58 patients. Finally, 125 lesions were confinmed as malignant, of which 58 (46.4%) lesions were less than 1.0 cm. The other 22 lesions were confinmed as benign, of which 17 (77.3%) lesions were less than 1.0 cm. The diagnostic accuracy of routine PET-CT, ceCT and ¹⁸F-FDG PET-ceCT in colorectal cancer liver metastasis for the lesions more than 1.0 cm was 100%, 93.1%, 100% respectively, and the consistency with final diagnosis was perfect, moderate, and perfect respectively (Kappa value 01.00, 0.408, 1.00). For the lesions less than 1.0 cm, the accuracy was 42.7%, 78.7%, 94.7% respectively, and the consistency with definitive diagnosis was insignificance, fair, and almost perfect respectively (Kappa value -0.005, 0.305, 0.848). The area under curve(AUC) was 0.525 (95% CI: 0.407-0.462) for routine PET-CT, 0.651(95% CI:0.532-0.757) for ceCT, and 0.924 (95% CI:0.839-0.972) for ¹⁸F-FDG PET-ceCT respectively. The AUC of ¹⁸F-FDG PET-ceCT was significantly larger than that of routine PET-CT (Z=5.559, P<0.05) or ceCT (Z=4.183, P<0.05).</p><p><b>CONCLUSION</b>(18)F-FDG PET-ceCT can improve the diagnostic accuracy for smaller lesions of colorectal cancer liver metastasis.</p>
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Humans , Colorectal Neoplasms , Contrast Media , Fluorodeoxyglucose F18 , Liver Neoplasms , Multimodal Imaging , Positron-Emission Tomography , Retrospective Studies , Tomography, X-Ray ComputedABSTRACT
<p><b>OBJECTIVE</b>To investigate the value of water enema (18)F-fluorodexyglucose positron emission tomography and computed tomography((18)F-FDG PET-CT) in incidental finding of hypermetabolism focus in the colon and rectum for differential diagnosis of benign or malignant lesions.</p><p><b>METHODS</b>From June 2010 to December 2012 in our hospital, 77 patients were found incidentally with uncertain hypermetabolism focuses in the colon and rectum during PET-CT examination. Water enema (18)F-FDG PET-CT was performed to classify the lesions. According to the pathological examination and clinical follow-up, these cases were divided into malignant disease (including advanced colorectal adenoma), benign adenoma, inflammation and physiological uptake. Radioactive uptake level (SUVmax) and change of water enema imaging (retention index, RI) of hypermetabolism focus were compared between groups.</p><p><b>RESULT</b>Of these 77 cases, 23 were malignant diseases, 16 benign adenoma, 7 inflammation and 31 physiological uptake. The difference of average SUVmax was not statistically significant between benign and malignant lesions as well as physiological uptake(P>0.05). But the difference of RI was statistically significant between neoplastic lesions and inflammation(P<0.05). The accuracy of water enema (18)F-FDG PET-CT in diagnosing non-neoplastic uptake was 100%, and the sensitivity, specificity and accuracy in differentiation of malignancy form benign lesions were 95.6%, 96.3%, and 96.1% respectively.</p><p><b>CONCLUSIONS</b>The incidental focal colorectal (18)F-FDG uptake in PET-CT may indicate potential colorectal malignant lesions and adenoma. Water enema can effectively differentiate the physiological uptake and predict benign lesions or malignancy in the colon and rectum colorectum with good accuracy.</p>