The Research On CT And MRI Features And Misdiagnosis Of Abdominal Spleen Implantation

Objective:To investigate the clinical and imaging features of abdominal spleen implantation and the causes of misdiagnosis,so as to improve the understanding and diagnosis of the disease.Methods:The clinical and imaging data of 54 patients with abdominal spleen implantation were collected from the Affiliated Hospital of Guizhou Medical University and Guizhou Provincial Cancer Hospital from January 2016 to March2021,and 54 patients with abdominal spleen implantation were diagnosed with surgical pathology or follow-up diagnosis,Among them,27 patients with 53 lesions underwent CT plain scan and enhanced examination,27 patients with 37 lesions underwent CT plain scan,7 patients with 19 lesions underwent MRI examination at the same time（3 patients with 8 lesions underwent MRI enhanced examination）.The gender,age,clinical symptoms,past history,location and size of implanted spleen,plain and enhanced CT and/or MRI findings were analyzed,and the differences between implanted spleen and normal erector spinae muscle and liver CT values were compared.In addition,40 patients with paraspleen were randomly collected from the clinical and imaging follow-up diagnosis in our hospital at the same time.The data of CT plain scan and enhancement examination were complete.The difference of the occurrence,size,CT plain scan and three-stage enhancement of the planted spleen and the secondary spleen were statistically analyzed,and the differences between the CT values of the implanted spleen,the paraspleen and the liver were compared.Results:（1）There were 39 males and 15 females with an average age of（51.13±13.22）years.The patients had a history of splenectomy ranging from 7 months to 40years.Among them,47 cases underwent emergency splenectomy due to splenic rupture caused by trauma,3 cases underwent splenectomy due to hypersplenism,and2 cases underwent splenectomy due to splenic space occupying and pancreatic space occupying respectively;There were no specificity in clinical symptoms;（2）Among them,3 cases were misdiagnosed as gastric stromal tumor,2 cases were misdiagnosed as pheochromocytoma and adenoma,2 cases were misdiagnosed as residual spleen,1case was misdiagnosed as hepatic adenoma,1 case was misdiagnosed as liver tumor and lymph node metastasis,1 case was misdiagnosed as abdominal cavity and small intestine One case of abdominal and pelvic spleen implantation was misdiagnosed as enlarged lymph node,another cases of left adrenal gland and abdominal cavity were misdiagnosed as masses of undetermined nature.（3）Imaging findings:1)the occurrence site:there were 90 lesions in the abdominal ectopic spleen implantation,including 37 lesions（41.11%）were located in the spleen area,16（17.77%）in the pancreatic tail area,14（15.55%）behind the stomach bottom,7（7.77%）in the pelvic cavity,6（6.66%）in left adrenal region,3（3.33%）in fundus of stomach,2（2.22%）in liver,right adrenal region and 2 in retroperitoneal region,and 1（1.11%）in the lower margin of the right lobe;2)the shape of the lesions:81 lesions（90%）were round or oval and 9（10%）lesions were irregular;3)the size of the lesions:the mean diameter line（2.56±1.47）cm;4)CT findings:the density of the nodules or masses was uniform in plain scan,which was lower than that of normal liver and spinal muscle.The shape was regular and the boundary was clear.The CT value was about（47.07±6.77）HU;the arterial phase of contrast-enhanced scan,the lesions with the maximum diameter less than 3cm showed mild to moderate homogeneous enhancement,while those with the maximum diameter more than 3cm showed heterogeneous enhancement[CT value was about（76.4±15.37）HU],and the portal vein was continuously strengthened[CT value was（103.52±21.26）HU],and the intensity of delayed phase decreased slightly[CT value was about（89±16.16）HU];4)MR findings:lesions showed isointense/slightly hypointense on T₁WI（n=19）,isointense/slightly hyperintense on T₂（n=12）,hypointense on T₂WI（n=7）,hyperintense on DWI and hypointense on ADC（n=19）.The enhancement mode of MRI was the same as that of CT.（4）The size,distribution and three-phase enhanced arterial phase of the implanted spleen and accessory spleen were statistically significant,but there was no significant difference between them in three-phase enhanced portal phase and delayed phase;the differences between the CT values of the implanted spleen and spleen in plain scan and three-phase enhanced arterial phase were statistically significant.Conclusion:1.Abdominal spleen implantation is found in patients with splenic trauma or splenectomy history,and the clinical symptoms are not specific;2.Imaging findings of abdominal spleen implantation have certain characteristics,mainly in the upper abdominal cavity,the most common in the spleen area,the distribution range is wider than the accessory spleen,the volume is larger than the accessory spleen;CT scan density is lower than the spleen,accessory spleen,liver,erector spinae muscle;MRI lesions showed equal/slightly long T₁,slightly long T₂signal,DWI showed high signal with reduced ADC signal;enhanced scan show that arterial phase enhancement degree is lower than the spleen and accessory spleen,the uniformity of enhancement is related to the size of the lesion.The portal phase and delayed phase showed continuous homogeneous enhancement similar to the spleen;3.The main reason of misdiagnosis is lack of understanding and knowledge for abdominal spleen implantation.