Incremental Value of 18F-PSMA-1007 PET/CT in Detection of Metastatic Renal Cell Carcinoma to the Brain.

ABSTRACT: 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.

Can Gallium-68 Prostate-specific Membrane Antigen Ligand be a Potential Radiotracer for Renal Cortical Positron Emission Tomography Imaging?

Gallium-68 prostate-specific membrane antigen (Ga-68 PSMA) ligand (HBED-CC) is a new promising positron emission tomography (PET) tracer for prostate cancer. Intense renal parenchymal uptake is a physiologic finding on Ga-68 PSMA ligand PET images. Evaluation of kidneys in low intensity demonstrates excellent distribution of this radiotracer in renal parenchyma with excellent image quality and resolution. In this article, we present the Ga-68 PSMA ligand PET renal images of four patients with prostate cancer. In two patients, there is normal distribution of radiotracer, and in other two, there are renal cysts causing parenchymal defects.

Gallbladder activity on sodium fluoride positron emission tomography/computed tomography bone scan.

We incidentally identified gallbladder activity on 18F sodium fluoride (NaF) positron emission tomography/computed tomography (PET/CT) bone images in five patients. Variable degree of bowel activity is usually seen on NaF PET/CT images, and its mechanism is unknown. Gallbladder activity in our cases may indicate that hepatobiliary excretion of the 18F NaF is the reason for bowel activity on NaF PET/CT images. However, excretion of radiotracer through bowel may also contribute to the bowel activity.

Ewing sarcoma of the rib with normal blood flow and blood pool imagings on a 3-phase bone scan.

Ewing sarcoma is the second most common pediatric malignant bone tumor. It usually presents as a hot spot on a 3-phase bone scan as a result of increased vascularity of the tumor and new bone formation. However, aggressive Ewing sarcoma can also appear as a cold lesion. We present the features of a Ewing sarcoma of the rib on a 3-phase bone scan in a child who was being investigated for rib fracture after trauma.

A comparison of myocardial perfusion gated SPECT studies obtained at rest and after stress.

OBJECTIVE: To perform a comparison between post-stress and rest gated single-photon emission computer tomography (SPECT) myocardial perfusion imaging (MPI) studies to assess post-stress stunning and the variables underlying this phenomenon. SUBJECTS AND METHODS: This was a prospective study of 318 consecutive adult patients undergoing stress and rest gated SPECT using a 2-day (99m)Tc-tetrofosmin protocol. Bruce protocol treadmill stress (n = 93) or i.v. dipyridamole pharmacologic stress (n = 225) were used as stressors. Ejection fractions (EF) and left ventricular (LV) end-diastolic (EDV) and end-systolic volumes (ESV) were calculated using the Cedars Sinai Quantitative Gated SPECT software. Perfusion defects were visually scored using a 20-segment model to obtain summed stress scores. Statistical analysis was performed by applying paired t test and multi-regression. Statistically significant (p < 0.05) paired differences between post-stress and rest EF and ESV and type of stressing were noted. RESULTS: Analysis of patient groups based on the type of stress showed significantly low EF on post-stress studies for both treadmill and dipyridamole stressing and also significantly high ESV on post-stress studies for dipyridamole. Multi-regression analysis using differences in post-stress and rest EF, EDV and ESV as dependent and summed stress scores, type of stress, delay time, previous myocardial infarction and size of LV as independent variables showed statistically significant associations between high summed stress scores (>13) and size of post-stress LV for EDV and ESV differences. High volumes were noted on post-stress studies. The magnitudes of the observed differences were well within the reproducibility of LV volume calculations. CONCLUSIONS: Patients showing stunning had significant ischemia or a dilated LV. The stunning manifested as high EDV and ESV differences. The magnitude of the differences observed in EF and LV volumes were not clinically significant.