This is a prospective, multicenter diagnostic imaging study designed to evaluate the diagnostic accuracy and clinical utility of BCMA-targeted positron emission tomography/computed tomography (PET/CT) in patients with multiple myeloma and related plasma cell disorders. The study aims to non-invasively visualize and quantify whole-body BCMA expression and to assess its role in the detection of active disease and disease heterogeneity.

This study is a prospective, multicenter diagnostic imaging investigation designed to evaluate the clinical value of BCMA-targeted positron emission tomography/computed tomography (PET/CT) in patients with multiple myeloma and related plasma cell disorders across different disease states.

Participants will undergo 68Ga-labeled BCMA PET/CT imaging in accordance with a standardized imaging protocol. Imaging findings will be assessed for the presence, distribution, and intensity of BCMA expression at both lesion-based and patient-based levels. Where clinically feasible, imaging findings will be correlated with histopathologic confirmation obtained from biopsy, which will serve as the reference standard for evaluation of diagnostic accuracy.

In addition to lesion detection, this study will explore the relationship between BCMA PET/CT findings and established clinical, laboratory, and imaging parameters. These include conventional imaging modalities, indicators of disease burden, and minimal residual disease (MRD) assessments when available. Longitudinal clinical follow-up will be conducted to assess changes in imaging findings over time and their association with treatment response and disease status.

In a subset of participants, circulating soluble BCMA (sBCMA) levels will be measured in peripheral blood samples collected within a predefined time window around the time of PET/CT imaging. Exploratory analyses will be performed to evaluate the association between sBCMA levels, imaging-derived measures of BCMA expression, and other indicators of disease burden. These analyses are intended to provide complementary biological context for imaging findings and to explore the potential role of integrating imaging and blood-based biomarkers in the assessment of multiple myeloma.

By integrating advanced molecular imaging with clinical, pathological, and biological data, this study aims to characterize whole-body disease burden and heterogeneity in a non-invasive manner and to define the potential clinical utility of BCMA PET/CT for diagnosis, response assessment, and disease monitoring in multiple myeloma.

Inclusion Criteria:

• patients with suspected or previously diagnosed multiple myeloma (MM) who were scheduled for bone marrow aspiration or tissue biopsy within two weeks, including those undergoing initial diagnostic evaluation or follow-up/re-evaluation for disease monitoring or relapse;
• patients with confirmed symptomatic MM;
• ability to understand and voluntarily sign written informed consent;
• ability to comply with study procedures;
• Eastern Cooperative Oncology Group (ECOG) performance status ≤2.

Exclusion Criteria:

• pregnancy or lactation;
• inability to comprehend study procedures or cooperate with protocol requirements;
• any other condition judged by the investigator to potentially interfere with study participation.

The current approved study protocol and informed consent documents do not include provisions for broad sharing of individual participant data with external researchers. The data generated in this study are complex, integrating detailed clinical information with advanced imaging biomarkers, and contain potentially identifiable and sensitive health information. Preparing these data for public sharing would require substantial additional resources and governance frameworks beyond the scope of the present study.

De-identified data may be made available for collaborative research upon reasonable request to the Principal Investigator, subject to scientific review and execution of appropriate data use and transfer agreements, and in accordance with applicable regulations and institutional policies.