Spectrum of the prostate lesions with increased FDG uptake on 18F-FDG PET/CT

FDG PET/CT in 2 Cases of Primary Urothelial Carcinoma of the Prostate

ABSTRACT

Primary prostatic urothelial carcinoma is a very rare aggressive tumor with poor prognosis. We describe FDG PET/CT findings in 2 patients with primary prostatic urothelial carcinoma. In 1 patient, FDG PET/CT showed intense activity of the prostate tumor with extraprostatic invasion. In the other patient, FDG PET/CT showed heterogeneous intense activity of the primary tumor and multiple hypermetabolic metastases in the regional lymph nodes, bone, and lung. Both patients had normal serum total prostate-specific antigen levels. These cases highlight the usefulness of FDG PET/CT in detecting and staging of primary prostatic urothelial carcinoma due to high FDG avidity.

FDG PET/CT in Prostate Metastasis From Gastric Cancer

ABSTRACT

Prostate metastasis from gastric cancer is rare. We report MRI and FDG PET/CT findings in a case with prostate metastasis from gastric cancer. In this case, the prostate metastasis was the first manifestation of the gastric cancer. This case demonstrates the usefulness of FDG PET/CT in identifying the primary gastric cancer and its contribution for an accurate staging. Familiarity with the FDG PET/CT findings of the prostate metastasis may be useful for the differential diagnosis of the hypermetabolic prostate lesions.

FDG PET/CT in a Case With Primary Poorly Differentiated Urothelial-Type Adenocarcinoma of the Prostate

ABSTRACT

Primary urothelial-type adenocarcinoma of the prostate is extremely rare. We describe FDG PET/CT findings in a case with primary poorly differentiated urothelial-type adenocarcinoma of the prostate with pelvic lymph node metastases. Both the prostate tumor and its metastatic lesions showed intense FDG uptake. The patient had normal serum prostate-specific antigen and elevated carcinoembryonic antigen levels, which may be helpful for the differential diagnosis.

Prostate incidentaloma on 18F-fluorodeoxyglucose positron emission tomography: Diagnostic value of volumetric positron emission tomography parameters

OBJECTIVE

To evaluate whether volumetric PET parameters such as metabolic tumor volume (MTV) and total lesion glycolysis (TLG) contributed to maximum standardized uptake value (SUVmax) in predicting prostate carcinoma in the prostate incidentalomas (PI) in 18F-FDG PET/CT.

MATERIALS AND METHODS

This retrospective study comprised 107 patients with PI of 4723 male patients who had undergone 18F-FDG PET/CT. SUVmax and volumetric PET parameters of PIs were assessed. MTV and TLG were acquired with each SUV threshold as 2.5, 3.0, 3.5, 4.0, 4.5, and 5.0.

RESULTS

The PI incidence was 2.3%, and the malignancy ratio of PI was 15.9%. According to further analysis results, 17 patients were in the malignant group, and 46 patients were in the benign group. Malignant PIs had higher SUVmax (10.6 vs. 6.4 and p<0.01), MTV (all p < 0.01) and TLG (all p < 0.01) than benign incidentalomas. All volumetric PET parameters had higher area under the curve (AUC) than SUVmax. SUVmax AUC was 0.835 [95% confidence interval (CI): 0.728-0.942]. MTV 2.5 and TLG 2.5 had the highest performance for predicting malignant PI.MTV2.5 AUC was 0.871 (95% CI: 0.775-0.968), and TLG2.5 AUC was 0.882 (95% CI: 0.797-0.967). Using TLG 2.5 greater than 29.8 as the cut-off point, the sensitivity and specificity for malignancy prediction were 94.1% and 82.6%, respectively.

CONCLUSION

In this study, in which the effectiveness of volumetric parameters in the diagnosis of PI was evaluated for the first time, it was shown that they could potentially have clinical value along with SUVmax.

Prevalence and clinical significance of incidental (18)F-fluoro-2-deoxyglucose uptake in prostate

Purpose

To investigate the prevalence and clinical significance of incidental prostate fluoro-2-deoxyglucose (FDG) uptake and to evaluate its impact on patient management.

Materials and Methods

Of 47,109 men who underwent FDG positron emission tomography between 2004 and 2014, 1,335 (2.83%) demonstrated incidental FDG uptake in the prostate, with 99 of the latter undergoing prostate biopsy. The primary end point was the histological presence of prostate adenocarcinoma in the biopsy specimen. Outcomes, including treatment methods, survival, and causes of death, were also assessed. Factors associated with the diagnosis of prostate cancer were evaluated by using logistic regression analysis.

Results

Patients with prostate cancer were more likely to have higher serum prostate-specific antigen (PSA) (p=0.001) and focal FDG uptake (p=0.036) than were those without. Prostate cancer occurred in 1 of 26 patients (3.8%) with serum PSA<2.5 ng/mL, compared with 40 of 67 patients (59.7%) with serum PSA≥2.5 ng/mL. Multivariable analysis showed that focal lesions (odds ratio [OR], 5.50; p=0.038), age (OR, 1.06; p=0.031), and serum PSA (OR, 1.28; p=0.001) were independent predictors of prostate cancer diagnosis. Most patients with prostate cancer had organ-confined tumors. Of these, 12 (29.3%) underwent radical prostatectomy and 25 (60.9%) received hormone therapy. Of the 11 patients who died, 9 died of primary cancer progression, with only 1 patient dying from prostate cancer.

Conclusions

The prevalence of incidental FDG uptake in the prostate was not high, although patients with elevated serum PSA had a higher incidence of prostate cancer. Patients with FDG uptake in the prostate should be secondarily evaluated by measuring serum PSA, with those having high serum PSA undergoing prostate biopsy.