| Abstract:Objective:Lymphoma is one of the most common malignant tumors in lymphatic hematopoietic system. Although lymphoma originates from the lymph nodes and lymphoid tissues, it often involves many extranodal organs and tissues, such as lung, gastrointestinal tract, skin, muscle, bone, liver, spleen, and so on. Splenic involvement is one of the common extranodal lesions of lymphoma. Patients diagnosed as lymphoma with18F-FDG PET/CT were retrospectively analyzed. The application value of18F-FDG PET/CT in the diagnosis of splenic involvement of lymphoma was discussed in this study. Method:18F-FDG PET/CT radiological findings of136patients with lymphoma included in the study were retrospectively analyzed. One hundred and thirty-six patients were divided into spleen positive group and spleen negative group according to the presence of spleen involvement or not. The radiological criteria of splenic infiltration of lymphoma were defined as follows:A, criteria of splenomegaly on CT:On axial CT, spleen maximum level is more than5rib units, or spleen vertical length is more than17cm, or the inferior margin of spleen is lower than that of liver; B, criterion of positive F-FDG uptake on PET:the ratio of maximum standard uptake value (SUVmax) of partial or whole spleen and normal liver SUVmax is greater than1; C, the imaging findings of spleen are consistent with that of A and B at the same time. Spleen volume, SUVmax and the percentage of extranodal lesions besides spleen of the two groups was compared. Spleen positive group was classified and analyzed in further according to the clinical stage and splenic imaging findings. Patients in spleen positive group were divided into stage Ⅰ to Ⅳ four stages according to the clinical stage and five groups according to the18F-FDG PET/CT imaging features of spleen lesions:group A (simple splenomegaly without abnormal glucose metabolism activity), group B (simple splenic diffusely increased glucose metabolic activity), group C (splenomegaly with diffusely increased glucose metabolic activity), group D (splenic single nodular increased glucose metabolic activity), and group E (splenic multiple nodules/masses increased glucose metabolic activity).18F-FDG PET/CT radiological features of spleen in lymphoma patients were revealed in this study. Results:Among the136cases of lymphoma patients, there were52cases in spleen positive group and84cases in spleen negative group. On axial view, spleen maximum level of the two group was on average5.08±1.10and3.73±0.64rib units, respectively. The spleen vertical length was (15.51±4.48)cm and (10.54±2.36)cm, respectively. SUVmax was7.35±5.97and2.37±0.57, respectively. The percentage of extranodal lesions besides spleen of the two groups was84.6%and47.6%, respectively. The above data differences were statistically significant (P value is less than0.05).52 cases in spleen positive group is divided into stage Ⅰ to Ⅳ four stages according to the clinical stage. The case number of stage Ⅰ to Ⅳ was3,6,19, and24cases, respectively. The SUVmax of stage Ⅰ to Ⅳ was2.67±1.63,3.33±2.46,10.52±7.4and6.43±4.27, respectively. The metabolism activity of spleen in stages Ⅲ-Ⅳ lymphoma patients were higher than those of stages Ⅰ-Ⅱ lymphoma patents. Fifty-two spleen positive group patients were divided into5groups according to the F-FDG PET/CT imaging features of spleen lesions:group A (simple splenomegaly without abnormal glucose metabolism activity)11cases, group B (simple splenic diffusely increased glucose metabolic activity)7cases, group C (splenomegaly with diffusely increased glucose metabolic activity)16cases, group D (splenic single nodular increased glucose metabolic activity)2cases, and group E (splenic multiple nodules/masses increased glucose metabolic activity)16cases. Spleen maximum level of the each group was on average:group A (5.36±0.92), group B (4.29±0.95), group C (5.19±1.04), group D (4.75±0.35) and group E (5.16±0.96) rib units, respectively. Spleen vertical length of each group was on average:group A (15.55±4.07) cm, group B (10.97±2.53) cm, group C (19.13±3.14) cm, group D (9.30±0.57) cm and group E (14.63±3.90) cm, respectively. The SUVmax(12.35±6.51) of multiple nodules/masses increased glucose metabolic activity group is significantly higher than that of other groups:group A (2.00±0.30), group B (5.9±4.58), group C (7.26±4.32), and group D (2.50±0.28).Conclusions:The spleen average volume, SUVmax and the percentage of extranodal lesions besides spleen of spleen positive group is larger or higher than corresponding index of spleen negative group. The glucose metabolism activity of stages Ⅲ-Ⅳ is higher that of stages Ⅰ-Ⅱ in spleen positive group. The main F-FDG PET/CT imaging findings included simple splenomegaly, simple splenic diffusely increased glucose metabolic activity, splenomegaly with diffusely increased glucose metabolic activity and splenic multiple nodules/masses increased glucose metabolic activity. Splenic multiple nodules/masses increased glucose metabolic activity can be combined with the splenomegaly, splenic diffusely increased glucose metabolic activity and two hybrid performance. The imaging finding was relatively more complicated. The metabolic activity of splenic multiple nodules/masses glucose metabolism activity was obviously higher than that of other groups. |
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