Intense PSMA Uptake in a Vertebral Hemangioma Mimicking a Solitary Bone Metastasis in the Primary Staging of Prostate Cancer via 68Ga-PSMA PET/CT

Sacral Hemangioma Mimicking Bone Metastasis on 18F-PSMA-1007 PET/CT

A 74-year-old man with prostate cancer was referred for an 18F-PSMA-1007 PET/CT scan for restaging due to a progressive rise in serum prostate-specific antigen levels. 18F-PSMA-1007 PET/CT showed a focal intense activity in the left sacral ala. The sacral lesion corresponded to a hemangioma, which was initially detected on pelvic MRI 6 months ago and remained stable in size. A second 18F-PSMA-1007 PET/CT performed 8 months after the first PET/CT showed no significant changes in size, density, and activity of the sacral lesion. This case indicates that hemangioma should be included in the differential diagnosis of PSMA-avid sacral lesions.

Neovascular prostate specific membrane antigen (PSMA) expression in bone and soft tissue sarcoma: a systematic analysis

Bone and soft tissue sarcomas are a highly heterogeneous group of rare cancers of mesenchymal origin. Treatment options other than surgery have limited efficacy due to low response rates with some exceptions. Radioligand therapy targeting prostate-specific membrane antigen (PSMA) may provide a novel treatment option, as it was recently suggested that soft tissue sarcomas express PSMA in the neovasculature, and on PET/CT imaging, multiple sarcomas have shown intense PSMA-tracer accumulation. Moreover, in prostate cancer patients, incidental PSMA uptake was seen in hemangiomas. In addition to confirming previous results in soft tissue sarcoma, the current study aims to systematically explore the expression of PSMA in bone tumors and in vascular tumors. Immunohistochemistry for PSMA was performed on a total of 706 tumors. High PSMA expression in the neovasculature was seen in 29% of the soft tissue sarcomas and 33% of the bone sarcomas. Malignant tumors showed a higher frequency of PSMA expression (score 2) as compared to benign tumors, with a high frequency in rhabdomyosarcoma (2 of 2, 100%), mesenchymal chondrosarcoma (14 of 20, 70%), undifferentiated sarcoma of bone (4 of 6, 67%) and of soft tissue (13 of 20, 65%), and osteosarcoma (46 of 81, 57%). In addition, giant cell tumor of bone displayed a high PSMA labelling in 67% of the cases. In contrast, high PSMA expression was seen in only 0-40% of the non-neoplastic vessels in vascular tumors, while 8% of them expressed PSMA in the tumor cells. Thus, with variable frequency among the different subtypes, a subset of bone and soft tissue tumors, both malignant and intermediate behavior, express PSMA and these patients may benefit from PSMA-targeting PET/CT scans or PSMA targeted radioligand therapy.

PSMA PET/CT imaging and its application to prostate cancer treatment

Recognition of the importance of prostate-specific membrane antigen (PSMA) PET/CT in the diagnosis of prostate cancer has steadily increased following the publication of extensive data on its diagnostic accuracy and impact on patient management over the past decade. Several recent clinical trials and investigations regarding PSMA PET/CT have been ongoing in our country, and this examination is expected to become increasingly widespread in the future. This review explains the characteristics of PSMA PET/CT, its diagnostic capabilities and superiority over other modalities, the three proposed PSMA PET/CT interpretation criteria (the European Association of Nuclear Medicine [EANM], the Prostate Cancer Molecular Imaging Standardized Evaluation [PROMISE], and the PSMA Reporting and Data System [PSMA-RADS]), and the application of PSMA PET/CT to prostate cancer treatment (improvement of local control, irradiation of oligometastases, and salvage radiotherapy), incorporating actual clinical images and the latest findings.

Hemangioma of the Ilium Simulating Bone Metastasis on 18 F-PSMA-1007 PET/CT

ABSTRACT

A 64-year-old man was referred for 18 F-PSMA-1007 PET/CT scan for initial staging of biopsy-proved prostate adenocarcinoma. 18 F-PSMA-1007 PET/CT showed focal intense 18 F-PSMA-1007 of the prostate adenocarcinoma and a focal intense activity with SUV max of 10.5 in the left ilium. The 18 F-PSMA-1007-avid iliac bone lesion corresponded to a hemangioma, which was initially detected on pelvic MRI 13 months ago and remained stable in size. This case indicates that hemangioma should be included in the differential diagnosis of PSMA-avid iliac bone lesions.

A tumor-like renal arteriovenous malformation on 18F-PSMA-1007 PET/CT: a case report

Background

Renal arteriovenous malformations (rAVMs) are congenital abnormal pathways between renal arteries and veins that are rare in the general population. It is often misdiagnosed as malignant renal tumors with abundant blood supply, and the definitive diagnosis primarily relies on angiography. Multimodality imaging, including contrast-enhanced computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET)/CT plays an important role in the differential diagnosis of renal space-occupying lesions.

Case presentation

A 56-year-old man presented with abdominal distension, loss of appetite, and back pain without obvious cause 2 years ago, without nausea vomiting, or frequent urination. Gastroscopy and colonoscopy showed multiple polyps in the duodenum and colon. Abdomen contrast-enhanced CT revealed a mass of 1.6 × 1.4 cm in the left kidney, which was considered to be a malignant tumor. PET/CT was performed for further diagnosis; the 18F-fluorodesoxyglucose (18F-FDG) PET/CT scan showed mild uptake in the left renal mass, while no uptake of 18F- prostate-specific membrane antigen (PSMA) was observed. Following a multidisciplinary discussion, the possibility of renal AVMs was considered and subsequently confirmed by renal angiography as the diagnosis. Then, selective segmental renal artery embolization was performed for treatment.

Conclusion

Renal AVMs are extremely rare in clinical practice. Due to limited research on the application of 18F-FDG and 18F-PSMA PET/CT to renal AVMs, its role remains largely unexplored. With the increasing popularity of PET/CT imaging, comprehensive imaging of the disease has become indispensable. We report the first case of PSMA PET/CT imaging in renal AVMs, and when PSMA expression is absent in a renal mass, the possibility of renal AVMs should be considered.

Intense 18 F-Prostate-Specific Membrane Antigen Uptake and Mild 18 F-FDG Uptake in a Biopsy-Proven Pulmonary Hemangioma

ABSTRACT

We present intense radiotracer activity in a soft tissue density abutting the aortic arch of the left lung on 18 F-prostate-specific membrane antigen PET/CT scan in a patient with prostate cancer, mimicking metastatic disease from prostate cancer versus primary lung malignancy. 18 F-FDG PET/CT scan, however, shows no elevated FDG activity. The results of pathology examination from resected specimen are consistent with pulmonary hemangioma.

Intense 18 F-PSMA-1007 Uptake of Splenic Hemangioma

ABSTRACT

A 77-year-old man was referred for 18 F-PSMA-1007 PET/CT scan for initial staging of biopsy-proved prostate adenocarcinoma. 18 F-PSMA-1007 PET/CT showed focal intense 18 F-PSMA-1007 of the prostate adenocarcinoma and a focal intense activity (SUV max , 27) in the spleen. The 18 F-PSMA-1007-avid splenic lesion corresponded to a splenic hemangioma, which was initially detected on contrast-enhanced CT 7 months ago and unchanged in size and enhancement pattern on follow-up contrast-enhanced CT. This case indicates that splenic hemangioma should be included in the differential diagnosis of PSMA-avid splenic lesions.

A Practical Guide to the Pearls and Pitfalls of PSMA PET Imaging

Prostate-specific membrane antigen (PSMA)-targeted PET agents have revolutionized the care of patients with prostate cancer, supplanting traditional methods of imaging prostate cancer, and improving the selection and delivery of therapies. This has led to a rapid expansion in both the number of PSMA PET scans performed and the imaging specialists required to interpret those scans. To aid those imagers and clinicians who are new to the interpretation of PSMA PET, this review provides an overview of the interpretation of PSMA PET/CT imaging and pearls for overcoming commonly encountered pitfalls. We discuss the physiologic distribution of the clinically available PSMA-targeted radiotracers, the commonly encountered patterns of prostate cancer spread, as well as the benign and malignant mimics of prostate cancer. Additionally, we review the standardized PSMA PET reporting systems and the role of PSMA in selecting appropriate patients for PSMA-targeted therapies.

How to Report PSMA PET

Prostate cancer (PCa) is the most common cancer diagnosed in men in most developed countries and a leading cause of cancer-related morbidity and mortality. Prostate-specific membrane antigen positron emission tomography (PSMA-PET) has become a valuable tool in the staging and assessment of disease recurrence in PCa, and more recently for assessment for treatment eligibility to PSMA radioligand therapy (RLT). Harmonization of PSMA-PET interpretation and synoptic reports are needed to communicate concisely and reproducibly PSMA-PET/CT to referring physicians and to support clinician therapeutic management decisions in various stages of the disease. Uniform image interpretation is also important to provide comparable data between clinical trials and to translate such data from research to daily practice. This review provides an overview of the value of PSMA-PET across the different clinical stages of PCa, discusses published reporting criteria for PSMA-PET, identifies pitfalls in reporting PSMA, and provides recommendations for synoptic reports.