| ObjectiveTo compare the value of various functional imaging methods(including 99Tcm-HYNIC-TOC SPECT,68Ga-DOTA-TATE PET/CT and 18F-FDG PET/CT)in the detection of tumors inducing osteomalacia;To analyze the value of MRI in the diagnosis and preoperative localization of TIO tumors and preliminarily investigate the relationship between extent of glucose metabolism,somatostatin expression and pathology of TIO causative tumors,as well as prognosis.MethodsIn the first part of the study,from March 2012 to December 2018,196 patients with suspicion of TIO or recurrent TIO causative tumors were recruited into this study.All patients performed 68Ga-DOTA-TATE PET/CT,72 of them underwent 18F-FDG PET/CT.Within 2 weeks beforehand,99Tcm-HYNIC-TOC SPECT were performed in all patients.The tracer-avid lesions were diagnosed of tumors inducing osteomalacia,apart from those demonstrating nonspecific uptake.Compared with the results of pathological examination and clinical follow-ups,the diagnostic performance of 99Tcm-HYNIC-TOC SPECT,68Ga-DOTA-TATE PET/CT and 18F-FDG PET/CT for TIO were calculated separately.Analyze the effect of lesion size,location,tissue origin and checking aim on the detection rates of various functional imaging methods.In the second part of the study,we retrospectively analyzed the 18F-FDG PET/CT and 68Ga-DOTATATE PET/CT images of 62 patients with TIO verified with results of pathological examination and clinical follow-ups.The detection rates of 18F-FDG and 68Ga-DOTATATE PET/CT were calculated for benign TIO causative tumors and lesions with malignant tendency,as well as tumors with Ki-67 index<5%and≥5%.Uptake levels were correlated with Ki-67 index and malignant tendency.Patients were divided into cured group and uncured group based on the results of follow-up,and the prognosis-related factors were analyzed.In the third part of the study,we retrospectively analyzed the 68Gα-DOTATATE PET/CT images of 75 patients with suspicion of TIO and MR images of the suspicious culprit lesions found in 68Ga-DOTATATE PET/CT images.Lesions presenting as a nodule or mass were diagnosed as TIO causative lesion on MRI scanning.Compared with the results of pathological examination and clinical follow-ups,accuracy of 68Ga-DOTATATE PET/CT for diagnosis of culprit tumors were analyzed,as well as combining 68Ga-DOTATATE PET/CT and MR imaging.The MR imaging features of TIO causative tumors were summarized.ResultsIn the first part of the study,amongst 196 patients,20 patients were excluded because of lack of evidence to confirm or exclude TIO,176 patients were included in the final analysis.147 patients were confirmed to have TIO while 29 were found to have other causes of hypophosphatemia.The sensitivities of 99Tcm-HYNIC-TOC SPECT,68Ga-DOTA-TATE PET/CT and 18F-FDG PET/CT for diagnosis of TIO causative tumor were 66%(97/147),97%(142/147)and 66%(97/147),the specificities were 90%(26/29),82%(24/29)and 90(9/10),and the overall accuracy were 70%(123/176),94%(166/176)and 70%(50/72).The sensitivity and accuracy of 68Gα-DOTA-TATE PET/CTw ere higher than that of 99Tcm-HYNIC-TOC-TOC SPECT and 18F-FDG PET/CT,and the difference were statistically significant(p<0.05).There’re no significant difference ie the sensitivity and accuracy between 99Tcm-HYNIC-TOC SPECT and 18F-FDG PET/CT(p>0.05).as well as the specificities between the three functional imaging methods.148 TIO causative tumors were confirmed and included in the assessment.The detection rates of 99Tcm-HYNIC-TOC SPECT,68Ga-DOTA-TATE PET/CT and 18F-FDG PET/CT were 70%(103/148),100%(148/148)and 68%(47/68).The detection rates of 99Tcm-HYNIC-TOC SPECT and 18F-FDG PET/CT for tumors with the maximum diameters less than 2cm were lower than that for tumors greater than 2cm,and the difference were statistically significant(p<0.05).The detection rate of 99Tcm-HYNIC-TOC SPECT for the lesions located in the soft tissues was higher than that located in the the bone and tissues adjacent to bone cortex(p<0.05).There’s no difference in the detection rate between primary and recurrent tumors,as well as lesions in various location.Compared with lesions detected by both 68Ga-DOTA-TATE PET/CT and 99Tcm-HYNIC-TOC SPECT,lesions detected by 68Ga-DOTA-TATE PET/CT,but miss diagnosed by 99Tcm-HYNIC-TOC SPECT tend to appear in the bone and tissue adjacent to bone cortex(p<0.05),and the maximum diameters of which were shorter(p<0.05).The maximum diameters of lesions detected by 68Ga-DOTA-TATE PET/CT,but miss diagnosed by 18F-FDG PET/CT were smaller(p<0.05)than those detected by both 18F-FDG and 68Ga-DOTA-TATE PET/CT.In the second part of the study,the detection rate of 18F-FDG PET/CT and 68Ga-DOTATATE PET/CT for TIO causative tumor were 66%and 100%.18F-FDG PET/CT showed a higher detection rate for tumors with malignant tendency and those with Ki-67 index≥5%.The average SUVmax of TIO causative tumors with malignant tendency and those with Ki-67 index≥5%were higher than that of benign tumors and those with Ki-67 index<5%on 18F-FDG PET/CT,and the difference was statistically significant(p<0.05).The average SUVmax of of TIO causative tumors with malignant tendency and those with Ki-67 index>5%were lower than that of benign tumors and those with Ki-67 index<5%on 68Ga-DOTA-TATE PET/CT,but the difference wasn,t statistically significant(p>0.05).As for lesions with malignant tendency and Ki-67 index≥5%,the average 18F-FDG SUVmax were lower than 68Ga-DOTA-TATE SUVmax,but the difference wasn’t statistically significant(p>0.05).meanwhile,the average 18F-FDG SUVmax of the lesions with malignant tendency and Ki-67 index>5%were significantly lower than 68Ga-DOTA-TATE SUVmax(p<0.05).50 patients were cured after operation while 12 patients were not cured.Lesion size,uptake of 18F-FDG and68Ga-DOTA-TATE and Ki-67 index were not prognosis-related factors.Disease duration,number of lesion,benign or malignant tendency,metastasis,involved scope,extent of resection were prognosis-related factors.In the third part of the study,amongst 75 patients,68 were confirmed to have TIO while 5 were found to have other causes of hypophosphatemia.Accuracy of 68Ga-DOTATATE PET/CT in detection of TIO causative tumors were 90.7%,and accuracy of 68Ga-DOTATATE PET/CT combining with MRI were 98.7%.Most of TIO causative tumors showed nodular and massive abnormal signal,except one located in the Cl.Most lesions showed iso-or hypointensity on the T1WI and hyperintensity on the T2WI and FS-T2WI.A small portion showed mixed signal,induced by calcification、fat and hemorrhage.Five lesions available on DWI showed no restricted diffusion,with iso-or hyperintensity on.ADC map.On contrast-enhanced Tl weight images,most of which showed obvious enhancement.Conclusion1.68Ga-DOTA-TATE PET/CT is superior to 99Tcm-HYNIC-TOC SPECT and 18F-FDG PET/CT in the detection of tumors inducing osteomalacia.99Tcm-HYNIC-TOC SPECT has a higher detection rate for the larger and soft tissue lesions.18F-FDG PET/CT has a higher detection rate for the larger lesions and those with malignant tendency and higher Ki-67 index.The detection rates of were not affected by the lesion location and checking aim.2.The lesion showing iso-or hypointensity on the T1WI,hyperintensity on T2WI and FS-T2WI,with obvious enhancement,and without restricted diffusion,tend to be diagnosed as TIO causative tumor.MRI can improve the diagnosis accuracy of 68Ga-DOTA-TATE PET/CT and definitely orientate the TIO causative tumors preoperativety.3.Extent of glucose metabolism of tumors was correlated with malignant tendency and Ki-67 index,which has no relationship with Ki-67 index.4.Extent of glucose metabolism and SSTR expression of causative tumors have no relationship with the prognosis of TIO,while,Disease duration,number of lesion,benign or malignant tendency,metastasis,involved scope,extent of resection are prognosis-related factors. |
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