Stereotactic Body Radiation Therapy (SBRT)-Induced 68 Ga-PSMA PET Bone Flare

Area of Science:

• Oncology
• Nuclear Medicine
• Radiotherapy

Background:

• Oligometastatic prostate cancer requires precise treatment strategies.
• Prostate-specific membrane antigen (PSMA) PET imaging is crucial for monitoring treatment response.
• Stereotactic body radiation therapy (SBRT) is an option for localized metastases.

Purpose of the Study:

• To report the first case of SBRT-induced bone flare observed on PSMA PET.
• To emphasize the importance of correctly interpreting early post-SBRT PSMA PET findings.

Main Methods:

• A 65-year-old man with oligometastatic prostate cancer received SBRT to a bone metastasis.
• Serial PSMA PET scans were performed post-SBRT to assess treatment response.
• Clinical and biochemical data (PSA levels) were monitored.

Main Results:

• Early PSMA PET showed increased uptake at the SBRT site, mimicking progression, despite a significant PSA decline.
• This increased uptake resolved on later imaging, consistent with bone flare.
• Subsequent imaging revealed new osseous metastases and rising PSA, indicating true disease progression.

Conclusions:

• SBRT can induce a transient bone flare on PSMA PET scans.
• Early post-SBRT PSMA PET findings require cautious interpretation to differentiate flare from progression.
• This case underscores the need for careful correlation of imaging findings with clinical and biochemical data.