FDG-PET Versus PSMA-PET: A Patient With Prostate Cancer

Abstract

<jats:p> A 64-year old male presented to the hospital with a 1-week history of stools with bright red blood. Subsequent colonoscopy with a biopsy revealed a low-lying, moderately differentiated, rectal adenocarcinoma. A pelvic magnetic resonance imaging done afterwards showed a possible T3N1 rectal cancer with intact muscularis mucosa and a singular presacral lymph node enlargement. Furthermore, a suspicious peripheral prostatic enlargement and a possible left iliac crest sclerotic bone lesion were incidentally identified. <jats:sup>18</jats:sup>F-FDG (fluorodeoxyglucose) PET (positron emission tomography) scan confirmed a primary FDG avid rectal tumor and a presacral lymph node; however, there was no prostate or iliac crest uptake. A serum prostate-specific antigen performed in the hospital returned with a value of 37 ng/mL, which prompted a prostate biopsy, eventually returning as positive for adenocarcinoma. Consequently, a <jats:sup>68</jats:sup>Ga-PSMA PET scan to rule out possible metastatic prostate disease revealed increased PSMA expression in the prostate only. After consultation with the radiologist and nuclear medicine physician who concluded the iliac crest lesion is likely not cancerous, the final diagnosis of T3N1 rectal cancer with simultaneous high-grade prostate adenocarcinoma was declared. This case highlights the low sensitivity of <jats:sup>18</jats:sup>F-FDG PET scans for prostate cancer, the need for routine serum prostate-specific antigen screening, and the progression of <jats:sup>68</jats:sup>Ga-PSMA PET as a diagnostic tool for prostate cancer. </jats:p>

A Case Report of a Patient With Prostate Adenocarcinoma Metastatic to the Posterior Peritoneum Despite the Negative Preoperative Prostate-Specific Membrane Antigen (PSMA) Positron Emission Tomography/Computed Tomography (PET/CT) Scan

“…Currently, PSMA-PET/CT has been shown to have greater sensitivity, specificity, and negative likelihood ratio in detecting lymph nodes and distant metastasis compared to conventional imaging like CT and MRI [3][4][5][6][7]. Recent studies also suggest that PSMA-PET/CT may have greater sensitivity in detecting bone metastasis when compared to traditional bone scintigraphy [7,10].…”

“…However, these imaging modalities are not the standard practices in the detection of PCa due to their limited sensitivities for smaller metastases and broad ranges. Choline-PET/CT was reported to have a sensitivity ranging from 73%-91%, and FDG PET/CT had a broad range of sensitivity of 4.0%-80% [ 1 , 4 ]. NaF-PET/CT detects bone metastasis and has shown to have significantly better sensitivity and specificity than conventional bone scintigraphy [ 3 , 5 ].…”

Imaging Recommendations for Theranostic PET-CT in Oncology

“…Supplementary Table S1 (in supplement) shows the comparison of CECT, FDG-PET-CT, MRI, and PSMA PET-CT for PC. 54 55 56 57 58 59 60 As shown in Table 1 , PSMA PET-CT is superior to the conventional imaging modalities for the localization of primary lesion, staging, and detection of relapse. Besides, PSMA PET-CT also gives lower radiation exposure when compared to CECT and FDG-PET-CT. Supplementary Table S2 (in supplement) shows the comparison of CECT, FDG-PET-CT, MRI, and 68 Ga- DOTATOC PET-CT for NET.…”

Evolving Castration Resistance and Prostate Specific Membrane Antigen Expression: Implications for Patient Management

“…Drug-related changes in PSMA expression intensity have to be incorporated as described earlier. Additionally, PSMA imaging enables the detection of tumor mass and heterogeneity and together with FDG-PET it might enable proper staging and the early recognition of tumor dedifferentiation to a more aggressive stage [108]. However, it has also been shown that neuroendocrine differentiation is not always associated with increased FDG uptake, indicating that decreasing PSMA expression is not generally replaced by rising GLUT levels and subsequent detectability by 18 F-FDG-PET [109].…”