A 64-year-old woman with metastatic breast cancer on follow-up had suspicious recurrent brain metastases. She underwent 18F-FDG PET/CT, 18F-PSMA 1007 brain PET/CT, and brain MRI. 18F-PSMA 1007 showed intense tracer localization in the suspected recurrent brain metastasis in right parietal lobe and also picked up 2 more metastatic brain lesions, which had concurrent findings of metastasis in subsequent MRI. Our case highlights the feasibility of 18F-PSMA 1007 PET/CT imaging of brain metastases from nonprostate cancers. It may be used as surrogate imaging tracer for potential theranostic application using alpha or beta emitters considering its similarity to PSMA-617.

A 64-year-old man with a known case of right parietal lobe glioblastoma multiforme operated on in August 2018 was referred for 18F-FDG PET/CT with a clinical suspicion of recurrence. He underwent 18F-FDG and 18F-PSMA 1007 scans. Both the scans showed intense tracer uptake in right parietal lobe lesion, which concurred with MRI findings of recurrent disease and was later proven on histopathologic examination as recurrence. Our case highlights the feasibility of 18F-PSMA 1007 PET/CT imaging of suspected glioblastoma recurrence. Considering its similarity to PSMA-617, it may be used as a surrogate imaging tracer for potential theranostic application using alpha or beta emitters.

18F-PSMA PET/CT is an emerging standard of care in staging prostate cancer, evaluating biochemical recurrence and response to therapy. Despite the nomenclature, PSMA expression is also documented at the tumor-associated neovasculature of other malignant solid tumors including renal cell carcinoma. We report a case of 44-year-old man known to have renal cell carcinoma who underwent 18F-PSMA and 18F-FDG PET/CT for restaging after radical nephrectomy. A well-defined solitary cerebellar lesion with marked PSMA expression and equivocal FDG uptake was noted. MRI brain confirmed a matching cerebellar metastatic lesion. 18F-PSMA expression in the metastatic RCC raises a prospective guide to futuristic theragnostic uses.

PurposeTo study the predictive and prognostic value of magnetic resonance imaging (MRI)–assessed tumor response after long-course neoadjuvant therapy for locally advanced rectal cancer.MethodsThis study included 79 patients who had T3 or T4 and/or N+ rectal cancer treated with long-course neoadjuvant chemoradiation. MRI-assessed tumor regression grade (mrTRG) was assessed in 64 patients. MRIs were reviewed by the study radiologist. Surgical and pathologic reports for those who underwent surgery were reviewed. Disease-free survival (DFS) was estimated. Progression during therapy, local relapse, metastasis, and death resulting from the tumor were classified as events. Statistical significance was calculated.ResultsIn 11 patients, the tumor completely disappeared on MRI; that is, it had an mrTRG of 1. All but one patient, who chose deferred surgery, had a complete pathologic response (pCR), with a positive predictive value of nearly 100%. Of the 20 patients who had an mrTRG of 2 on MRI, six had a pCR. mrTRG 3, mrTRG 4, and mrTRG 5 were detected in 24, six, and three patients, respectively, of whom only one patient had a pCR. The 2-year DFS was 77%. The mrTRG was significant for DFS. The 2-year DFS was 88% for patients with a good response versus 66% for those with a poor response (P = .046).ConclusionMRI-assessed complete tumor response was strongly correlated with pCR and, therefore, can be used as a surrogate marker to predict absence of viable tumor cells. Our results can be used to implement use of mrTRGs in larger prospective correlative studies as a tool to select patients for whom deferred surgery may be appropriate. Also, those with a poor response may be offered further treatment options before definitive surgery.

18 F-PSMA is a promising tracer for both staging and detection of biochemical recurrence in prostate cancer. PSMA is also expressed in the benign pathological conditions. We report a case of 81-year-old man with a known case of prostate cancer who underwent 18 F-PSMA for restaging. 18 F-PSMA PET/CT shows intense tracer uptake in the frontal bone appearing like an "Iron Man" sign. Corresponding noncontrast CT images, pagetoid changes with thickened cortex, mixed lytic/sclerotic mottled pattern. It is important to recognize 18 F-PSMA expression in the benign nonprostatic pathologies to avoid false interpretation.