¹⁸F-FDG PET-CT Application In Lymphoma

The relationship between SUVmax of 18F-FDG PET-CT and clinical staging, pathological classification and Ki-67 in lymphomaObjective The study aimed at investigating SUVmax of 18F-FDG PET-CT in relation to clinical staging, pathological classification and Ki-67 expression in lymphoma.Methods Data of 18F-FDG PET-CT imaging and immunohistochemical detection of Ki-67 expression of 135 cases with initially diagnosed lymphoma were retrospectively analyzed. Thirty-two cases were performed with PET-CT before biopsy, and 103 cases were performed with PET-CT after biopsy. According to Ann Arbor classification,24 cases were stage I,63 cases were stage Ⅱ,19 cases were stage Ⅱ,29 cases were stage Ⅳ. According to the World Health Organization classification of tumors,19 cases with HL and 116 cases with NHL were comfirmed by pathology. One hundred and sixteen cases with NHL had 94 cases with aggressive lymphoma and 22 cases with indolent lymphoma. SUVmax of whole-body lymphoma was measured.Results SUVmax of HL and SUVmax of NHL were 11.5±5.6 and 11.8±6.8. There was no significant difference between SUVmax of HL and SUVmax of NHL (P>0.05). SUVmax of lymphoma at stage I, stageⅡ, stage III and stage IV were 11.0±7.2, 13.1±7.0,10.5±6.2 and 10.4±5.2, respectively. No correlation was detected between SUVmax and clinical staging of lymphoma (P>0.05). SUVmax of aggressive lymphoma and SUVmax of indolent lymphoma were 13.0±6.5 and 6.8±5.7. Aggressive lymphoma had higher SUVmax than indolent lymphoma (P<0.05). Using a cut-off value of 8.4 for SUVmax, PET-CT had a maximum Youden’s index of 0.528. SUVmax and Ki-67 expression of lymphoma were 11.8±6.6 and (51.5±24.4)%. SUVmax correlated with Ki-67 expression in lymphoma (r=0.45,P<0.05). SUVmax and Ki-67 expression were 12.5±7.1 and (54.3±24.1)% in early-stage lymphoma (stage I and stage II), and 10.5±5.5 and (46.5±24.5)% in advanced-stage lymphoma (stage III and stage Ⅳ). SUVmax and Ki-67 expression were 11.5±7.7 and (48.6±24.8)% in lymphoma with PET-CT before biopsy, and 11.9±6.3 and (52.4±24.4)% in lymphoma with PET-CT after biopsy. A positive correlation between SUVmax and Ki-67 expression was revealed in early-stage lymphoma(r=0.44, P<0.05) or in advanced-stage lymphoma(r=0.43, P<0.05), and in lymphoma with PET-CT before biopsy(r=0.76, P<0.05) or in lymphoma with PET-CT after biopsy(r=0.35, P<0.05).Conclusion There was no significant correlation between SUVmax and clinical staging of lymphoma. Aggressive lymphoma has higher SUVmax than indolent lymphoma. SUVmax>8.4 may predict for aggressive histology in NHL. The result indicates that tumor proliferation potential might be predicted in vivo by 18F-FDG PET-CT. There is higher correlation between the SUVmax and Ki-67 expression in lymphoma with PET-CT before biopsy than lymphoma with PET-CT after biopsy.Correlation of 18F-FDG uptake with tumor-proliferating antigen Ki-67 expression in aggressive lymphomaObjective The study aimed at investigating 18F-FDG uptake in PET-CT in relation to Ki-67 expression in aggressive lymphoma.Methods Data of 18F-FDG PET-CT imaging and Ki-67 expression of 77 cases with initially diagnosed aggressive lymphoma were retrospectively analyzed. The intensity of 18F-FDG accumulation was determined by calculating the maximum standardized uptake value (SUVmax) and the mean standardized uptake value (SUVmean). SUVmax at the highest tumor activity site of whole body (BmSUVmax), SUVmax at biopsy site (BxSUVmax) and the mean SUV at biopsy site (BxSUVmean) were collected.Results BmSUVmax, BxSUVmax and BxSUVmean were 13.4±6.8,11.9±6.8 and 7.3±4.4 in aggressive lymphoma. BmSUVmax was significantly higher than BxSUVmax or BxSUVmean in aggressive lymphoma (P<0.05). A positive correlation was revealed between BmSUVmax and BxSUVmax (P<0.05), and between BxSUVmax and BxSUVmean (P<0.05) in aggressive lymphoma. Ki-67 expression was (61.2±20.4)% in aggressive lymphoma. BmSUVmax, BxSUVmax and BxSUVmean were positively correlated with Ki-67 expression in aggressive lymphoma (P<0.05). BmSUVmax and BxSUVmax were 15.6±6.6 and 14.0±7.1, and Ki-67 expression was (67.1±17.7)% in DLBCL. No correlation was detected between BmSUVmax or BxSUVmax and Ki-67 expression in DLBCL (P>0.05), but a positive correlation was noted in DLBCL with PET-CT before biopsy (P<0.05). BmSUVmax and BxSUVmax were 9.1±5.0 and 9.2±4.8, and Ki-67 expression was (56.4±21.5)% in NK/T cell lymphoma. A positive correlation was observed between BmSUVmax or BxSUVmax and Ki-67 in NK/T cell lymphoma (P<0.05).Conclusion The increasing trend of 18F-FDG uptake is correlated with Ki-67 expression in aggressive lymphoma. The result of this study suggests that the metabolic information obtained by using BmSUVmax may help to compensate the limited sampling of histological examination at the biopsy site. Significant correlation in NK/T cell lymphoma suggests the metabolic information from PET-CT may offer a useful parameter in the prognosis and management of this disease.Prognostic significance of SUVmax, MTV and TLG in patients with diffuse large B cell lymphomaObjective The aim of this study is to determine the predictive value of 18F-FDG PET-CT using SUVmax, MTV and TLG in patients with DLBCL.Methods This study retrospectively reviewed 46 patients with newly diagnosed DLBCL from 2008 to 2012. All patients had staging 18F-FDG PET-CT scan before chemotherapy. These patients underwent standard treatment and subsequently clinical follow-up. To define the exact tumor margins around the target lesions, SUVmax, MTV and TLG of whole-body tumor tissue in PET-CT was obtained with SUV cut-off value of 2.5. SUVmax, MTV and TLG were evaluated for their association with LDH level and survival. The correlations between SUVmax, MTV, TLG and LDH were analyzed using Spearman’s method to calculate the rank. The receiver operating characteristic (ROC) curve was plotted to estimate the most discriminating decision threshold (cut-off point) for each parameter to maximize the sensitivity and specificity in predicting the progression or recurrence of disease. The relationship between age, LDH level, Ann Arbor stage, extranodal involvement, SUVmax, MTV, TLG and PFS was estimated statistically by the Kaplan-Meier method and Log-rank test. SPSS version 13.0 was used for all analyses. A P<0.05 was considered statistically significant.Results No statistically significant correlation between SUVmax and LDH level (P>0.05). There were significant positive correlations between MTV and LDH level (r=0.710, P<0.05) and between TLG and LDH level (r=0.673, P<0.05). On ROC analyses, the optimal cut-offs of SUVmax, MTV and TLG were 19 g/ml,56 cm3 and 817 g/ml×cm3 for the progression or recurrence of disease. Kaplan-Meier method and Log-rank test showed intermediate-high IPI was associated with reduced PFS compared with low-risk PI (P<0.05) and high TLG (≥817 g/mlxcm3) was associated with reduced PFS compared with low TLG (<817 g/mlxcm3) (P<0.05). Age, LDH level, Ann Arbor stage, extranodal involvement, SUVmax and MTV did not significantly shorten PFS(P>0.05).Conclusion MTV and TLG correlate with level of LDH in DLBCL. Our findings suggest that TLG are more useful than SUVmax or MTV for predicting PFS in DLBCL. High TLG may be a useful tool to identify patients with DLBCL who are at increased risk for progression or relapse after therapy and to implement risk-adapted treatment.The application of 18F-FDG PET-CT in post-treatment assessment of residual mediastinal masses in Hodgkin’s lymphomaObjective The aim of this study is to evaluate the accuracy of 18F-FDG PET-CT and its dual-time scans in assessment of residual mediastinal masses in Hodgkin’s lymphoma after therapy.Methods Fifty consecutive HL cases with residual mediastinal masses were analyzed retrospectively. Thirty-four cases prospectively received dual-time scans. The first scan was at 60～70 min (scan 1) and the second scan was at 120～150 min (scan 2) after 18F-FDG injection. All cases were confirmed by at least 1-year follow-up.Results Thirteen cases with residual tumor were confirmed by follow-up evidence. Thirty-seven cases were still disease-free after at least 1-year follow-up. Using a cut-off value of 2.2 for SUVmax, PET-CT had a maximum Youden’s index of 0.503. Thus, the sensitivity, the specificity, the accuracy, the positive predictive value and the negative predictive value were 69.2%,81.1%,78.0%,56.2% and 88.2%, respectively in assessment of residual mediastinal masses. Using SUVmax>2.2 in scan 1, single-time scan of 34 cases had 5 true positive,21 true negative,6 false positive and 2 false negative. Using SUVmax>2.2 in scan 1 and a threshold value of 10% increase in scan 2, dual-time scans of 34 cases had 3 true positive,26 true negative,1 false positive and 4 false negative. Dual-time scans of 34 cases had 5 less false positive and 2 more false negative than single-time scan. No significant difference was noted between the single-time scan and dual-time scans in assessment of residual mediastinal masses (P>0.05).Conclusion 18F-FDG PET-CT is a suitable non-invasive method in assessment of residual masses of Hodgkin’s lymphoma after therapy. Dual-time PET-CT scans might be helpful to decrease false-positive rate.