This is an open-label whole-body PET/CT study for investigating the value of 68Ga-DOTA-TATE and 68Ga-DOTA-JR11 PET/CT in patients with Tumor-induced osteomalacia.

Tumor-induced osteomalacia (TIO), also known as oncogenic osteomalacia, is a rare paraneoplastic syndrome. The key to the cure of TIO is surgical resection of the culprit tumor. Over the last decade, 68Ga-labeled SSTR-based imaging has made a significant impact in detecting the culprit tumor of TIO 68Ga-DOTA-TATE is the most used SSTR PET tracer for the detection of TIO and it was recommended as first-line imaging method for localization of the causative tumor.

However, false positive, including fracture and/or inflammation, in 68Ga-DOTA-TATE PET/CT is a challenge in image interpretation, which may make the causative tumor indistinguishable in multiple suspicious lesions. There is no effective way to identify multiple suspicious lesions with intensive increased uptake on 68Ga-DOTA-TATE PET/CT.

68Ga-DOTA-JR11 is a SSTR2 specific antagonist used for PET tracer. However, the SSTR2 affinity of 68Ga-DOTA-JR11 is lower than 68Ga-DOTA-TATE, which means that the uptake of 68Ga-DOTA-JR11 by suspected lesions may be lower than that of 68Ga-DOTA-TATE. The purpose of this prospective study is to compare the sensitivity of 68Ga-DOTA-JR11 and 68Ga-DOTA-TATE PET/CT for detecting the responsible tumor of TIO and investigate if 68Ga-DOTA-JR11 PET/CT can identify the culprit tumor of TIO in multiple suspicious lesions.

Inclusion Criteria:

• suspected or confirmed untreated TIO patients;
• 68Ga-DOTA-TATE and 68Ga-DOTA-JR11 PET/CT within two weeks;
• signed written consent.

Exclusion Criteria:

• pregnancy;
• breastfeeding;
• any medical condition that in the opinion of the investigator may significantly interfere with study compliance.