68Ga-Prostate-Specific Membrane Antigen PET/CT Uptake in Intraventricular Meningioma in the Choroid Plexus

Late Subacute Cerebral Hematoma Mimicking a Metastasis on PSMA PET/CT

ABSTRACT

A 64-year-old man with history of prostate cancer was found to have rising prostate-specific antigen after radical prostatectomy. 18 F-DCFPyL PET/CT demonstrated a prostate-specific membrane antigen-avid brain lesion in the left frontal lobe and no other findings to account for rising prostate-specific antigen. Brain MRI demonstrated a small intraparenchymal hematoma with late subacute features in this location. The patient reported a seizure 3 weeks before but was otherwise asymptomatic, and neurologic examination was normal. Follow-up MRI demonstrated gradual decrease in size of the hematoma without treatment.

Incidental Meningioma With Altered PSMA Expression After Systemic Hormone Therapy and Local Radiotherapy Detected by 68 Ga-PSMA PET/CT

ABSTRACT

A 59-year-old man underwent radical prostatectomy for adenocarcinoma in 2009. Because of the progression of PSA levels, a 68 Ga-PSMA PET/CT scan was performed in January 2020. A suspicious uptake was detected in the left cerebellar hemisphere, and there was no evidence of distant metastatic disease other than recurrent malignancy in the prostatectomy bed. MRI revealed a meningioma located in the left cerebellopontine angle. Although PSMA uptake of the lesion increased in the first imaging after hormone therapy, partial regression was noted after radiotherapy applied to this region.

Increased 68Ga-FAPI Uptake in Psammomatous Meningioma in a Patient With Gallbladder Cancer

ABSTRACT

A 70-year-old woman with a gallbladder mass was enrolled in our clinical trial of 68Ga-FAPI PET/CT study in tumors. Increased tracer uptake was noted in the gallbladder. In addition, focal uptake was localized in a lesion beside the falx cerebri. According to the location and radiological and clinical characteristics, a diagnosis of meningioma was made.

Elevated 68Ga-FAPI Uptake by Primary Benign Intraosseous Meningioma

ABSTRACT

Intraosseous meningioma is an extremely rare benign tumor. We present the 68Ga-fibroblast activation protein inhibitor (FAPI) PET/CT findings of primary intraosseous meningioma in a 71-year-old woman. 68Ga-FAPI PET/CT revealed an intraosseous mass in the right parietal bone with increased FAPI activity. Primary skull malignancy was suspected. However, pathological examination after resection of the mass in the right parietal bone confirmed the diagnosis of benign meningioma (WHO I). A final diagnosis of benign intraosseous meningioma was made.

Prostate-Specific Membrane Antigen as Target for Neuroimaging of Central Nervous System Tumors

Introduction. Positron emission tomography (PET) imaging with prostate-specific membrane antigen- (PSMA-) binding tracers has been found incidentally to demonstrate uptake in CNS tumors. Following the encouraging findings of several such case reports, there is a growing interest in the potential application of PSMA-targeted PET imaging for diagnostics, theranostics, and monitoring of CNS tumors. This is a systematic literature review on PSMA-binding tracers in CNS tumors. Methods. A PubMed search was conducted, including preclinical and clinical reports. One hundred and twelve records were identified, and after screening, 56 were included in the final report. Results. Tissue studies demonstrated PSMA expression in tumor vascular endothelial cells, without expression in normal brain tissue, though the extent and intensity of staining varied by anti-PSMA antibody and methodology. Most included studies reported on gliomas, which showed strong PSMA ligand uptake and more favorable tumor to background ratios than other PET tracers. There are also case reports demonstrating PSMA ligand uptake in prostate cancer brain metastases, nonprostate cancer brain metastases, and meningiomas. We also review the properties of the various PSMA-binding radiotracers available. Therapeutic and theranostic applications of PSMA-binding tracers have been studied, including labeled alpha- and beta-ray emitting isotopes, as well as PSMA targeting in directing MRI-guided focused ultrasound. Conclusions. There is a potential application for PSMA-targeted PET in neuro-oncology as a combination of diagnostic and therapeutic use, as a theranostic modality for managing CNS tumors. Further research is needed regarding the mechanism(s) of PSMA expression in CNS tumors and its differential performance by tumor type.

Distinguishing Meningioma From Metastasis of Prostate Cancer on 68Ga-PSMA PET/CT

ABSTRACT

Meningiomas are typically benign and the most common primary brain tumors. They are usually diagnosed based on their characteristic appearance on both MRI and CT. Meningiomas can easily be misdiagnosed as metastasis of prostate cancer due to their high 68Ga-PSMA uptake on 68Ga-PSMA PET/CT. We present a case of a metastatic prostate adenocarcinoma with PSMA-avid lesion in the right frontal lobe on 68Ga-PSMA PET/CT. Later, MRI confirmed the brain lesion as meningioma.

Incidental prostate-specific membrane antigen-avid meningioma detected on 68Ga-prostate-specific membrane antigen PET/CT

A 70-year-old gentleman with a history of Gleason score 7 (3 + 4) prostate adenocarcinoma was treated with radical prostatectomy with clear surgical margins. Postoperatively his prostate specific antigen was undetectable. However, his prostate specific antigen was slowly rising and he was referred for a ⁶⁸Galium-Prostate Specific Membrane Antigen (PSMA) PET/CT scan. Findings were suggestive of local prostatic cancer recurrence with no evidence of nodal or distant metastasis. An incidental PSMA avid focus was noted in the left frontal lobe, inseparable from the left frontal bone laterally. Subsequent MRI findings were consistent with meningioma. Meningioma is the most common primary brain tumor and may be a cause of false positive prostate cancer metastasis due to ⁶⁸Ga-PSMA uptake.