Comparison of quantitative whole body PET parameters on [68Ga]Ga-PSMA-11 PET/CT using ordered Subset Expectation Maximization (OSEM) vs. bayesian penalized likelihood (BPL) reconstruction algorithms in men with metastatic castration-resistant prostate cancer.

BACKGROUND: PSMA PET/CT is a predictive and prognostic biomarker for determining response to [177Lu]Lu-PSMA-617 in patients with metastatic castration resistant prostate cancer (mCRPC). Thresholds defined to date may not be generalizable to newer image reconstruction algorithms. Bayesian penalized likelihood (BPL) reconstruction algorithm is a novel reconstruction algorithm that may improve contrast whilst preventing introduction of image noise. The aim of this study is to compare the quantitative parameters obtained using BPL and the Ordered Subset Expectation Maximization (OSEM) reconstruction algorithms. METHODS: Fifty consecutive patients with mCRPC who underwent [68Ga]Ga-PSMA-11 PET/CT using OSEM reconstruction to assess suitability for [177Lu]Lu-PSMA-617 therapy were selected. BPL algorithm was then used retrospectively to reconstruct the same PET raw data. Quantitative and volumetric measurements such as tumour standardised uptake value (SUV)max, SUVmean and Molecular Tumour Volume (MTV-PSMA) were calculated on both reconstruction methods. Results were compared (Bland-Altman, Pearson correlation coefficient) including subgroups with low and high-volume disease burdens (MTV-PSMA cut-off 40 mL). RESULTS: The SUVmax and SUVmean were higher, and MTV-PSMA was lower in the BPL reconstructed images compared to the OSEM group, with a mean difference of 8.4 (17.5%), 0.7 (8.2%) and - 21.5 mL (-3.4%), respectively. There was a strong correlation between the calculated SUVmax, SUVmean, and MTV-PSMA values in the OSEM and BPL reconstructed images (Pearson r values of 0.98, 0.99, and 1.0, respectively). No patients were reclassified from low to high volume disease or vice versa when switching from OSEM to BPL reconstruction. CONCLUSIONS: [68Ga]Ga-PSMA-11 PET/CT quantitative and volumetric parameters produced by BPL and OSEM reconstruction methods are strongly correlated. Differences are proportional and small for SUVmean, which is used as a predictive biomarker. Our study suggests that both reconstruction methods are acceptable without clinical impact on quantitative or volumetric findings. For longitudinal comparison, committing to the same reconstruction method would be preferred to ensure consistency.

A PSMA PET/CT-based risk model for prediction of concordance between targeted biopsy and combined biopsy in detecting prostate cancer.

PURPOSE: This study is to investigate the diagnostic value of 68Ga-PSMA-11 in improving the concordance between mpMRI-TB and combined biopsy (CB) in detecting PCa. METHODS: 115 consecutive men with 68Ga-PSMA-11 PET/CT prior to prostate biopsy were included for analysis. PSMA intensity, quantified as maximum standard uptake value (SUVmax), minimum apparent diffusion coefficient (ADCmin) and other clinical characteristics were evaluated relative to biopsy concordance using univariate and multivariate logistic regression analyses. A prediction model was developed based on the identified parameters, and a dynamic online diagnostic nomogram was constructed, with its discrimination evaluated through the area under the ROC curve (AUC) and consistency assessed using calibration plots. To assess its clinical applicability, a decision curve analysis (DCA) was performed, while internal validation was conducted using bootstrapping methods. RESULTS: Concordance between mpMRI-TB and CB occurred in 76.5% (88/115) of the patients. Multivariate logistic regression analyses performed that SUVmax (OR= 0.952; 95% CI 0.917-0.988; P= 0.010) and ADCmin (OR= 1.006; 95% CI 1.003-1.010; P= 0.001) were independent risk factors for biopsy concordance. The developed model showed a sensitivity, specificity, accuracy and AUC of 0.67, 0.78, 0.81 and 0.78 in the full sample. The calibration curve demonstrated that the nomogram's predicted outcomes closely resembled the ideal curve, indicating consistency between predicted and actual outcomes. Furthermore, the decision curve analysis (DCA) highlighted the clinical net benefit achievable across various risk thresholds. These findings were reinforced by internal validation. CONCLUSIONS: The developed prediction model based on SUVmax and ADCmin showed practical value in guiding the optimization of prostate biopsy pattern. Lower SUVmax and Higher ADCmin values are associated with greater confidence in implementing mono-TB and safely avoiding SB, effectively balancing benefits and risks.

A pictorial view on false positive findings of 68Ga-PSMA-11 PET/CT and their prognostic value in patients with prostate carcinoma after radical prostatectomy and undetectable PSA values.

OBJECTIVE: Recently, gallium-68-prostate-specific membrane antigen-11 (68Ga-PSMA-11) positron emission tomography/computed tomography (PET/CT) has become a key imaging method in prostate carcinoma staging and biochemical progression, with varying sensitivities in different studies (from 40% to 80%). After four years of experience with 68Ga-PSMA-11 PET/CT, we found that it is possible to detect lesions with increased PSMA expression in patients with undetectable prostate specific antigen (PSA) levels after radical prostatectomy. The key questions we wanted to answer were as follows: if those lesions were malignant and could the early detection of those malignant lesions have a role in patient management? We aimed to identify and follow up PSMA-positive findings for a period of 4 years in patients with prostate cancer after radical prostatectomy and undetectable PSA values at the time of the examination. We also explored false-positive lesions in detail. SUBJECTS AND METHODS: The study included all patients who underwent radical prostatectomy and had undetectable PSA values <0.05ng/mL and who underwent 68Ga-PSMA-11 PET/CT between July 2019 and December 2019. We performed 220 studies and found 40 patients with these characteristics; these patients were included in this study. All of them were followed up until July 2023. Any finding with increased radiopharmaceutical accumulation above the background activity in the respective area was considered a false positive. Prostate-specific membrane antigen accumulation in established lesions was assessed semi-quantitatively by the maximum standardized uptake value (SUVmax) and qualitatively by the four-point visual scale proposed in the E-PSMA recommendations. RESULTS: We found 15/40 (37.5%) patients with PSMA-positive findings. These were predominantly bone changes without a corresponding CT abnormality or discrete cystic or osteoblastic lesions with above-background increased PSMA expression. The mean SUVmax of these non-specific lesions was 3.02 (SD 2.86). After 3.5-4 years of follow-up, biochemical progression was found in only two of the patients.The great sensitivity of the method nowadays is a powerful engine for the development of new therapeutic options. On the other side, the lower specificity due to false positive findings, if misinterpreted, might lead to switching to a higher stage, with the planned radical treatment replaced by palliative treatment. CONCLUSION: The presence of 68Ga-PSMA-11 PET/CT-positive findings in patients after radical prostatectomy and an undetectable PSA had a low predictive value for future progression. The interpretation of 68Ga-PSMA-11 PET/CT should always include a complex assessment of the clinical setting-the risk group, PSA value and degree of PSMA accumulation in the lesions. In these situations, further clarification of PSMA-positive findings is appropriate before deciding to change treatment.

Cutaneous, Subcutaneous, and Bilateral Adrenal Gland Metastases in Progressive Prostate Carcinoma: Theranostic Potential of 68 Ga-PSMA-11 PET/CT Imaging and 177 Lu-PSMA-617 Therapy.

ABSTRACT: Prostate carcinoma (PC) is the second most common malignant tumor in males globally. The metastatic spread of PC usually involves the pelvic and abdominal lymph nodes and the skeletal system. Cutaneous metastases are exceedingly uncommon and typically manifest themselves late in the disease course, considered as ominous sign with limited treatment options and a poor prognosis. We describe a patient wherein 68 Ga-PSMA-11 PET/CT detected multiple uncommon metastatic sites in the cutaneous region of the scrotum, penis, and thigh, as well as in the subcutaneous region of anterior abdominal wall, and in bilateral adrenal glands. These findings served as a theranostic tool for selecting 177 Lu-PSMA-617 treatment for these extremely rare metastatic sites.

Clinical utility of [68Ga]Ga-PSMA-11 PET/CT in initial staging of patients with prostate cancer and importance of intraprostatic SUVmax values.

BACKGROUND: As in disease recurrence, providing clinicians with the exact extent of the disease at the time of initial diagnosis is key in the management and individual treatment of prostate cancer (PC) patients. Intending to examine the usefulness of gallium- 68 PSMA-11 positron emission tomography/computed tomography ([68Ga]Ga-PSMA-11 PET/CT) and to determine if there is a correlation between prostate-specific antigen (PSA) serum values, WHO/ISUP (World Health Organization/International Society of Urological Pathology's) grade group of the tumor and SUVmax (maximized standardized uptake value) values we retrospectively analyzed PET/CT studies performed for initial staging of the disease. PATIENTS AND METHODS: We retrospectively evaluated 34 studies of patients who underwent [68Ga]Ga-PSMA-11 PET/CT as part of the initial staging of prostate cancer. All patients had prostate cancer confirmed by histological assessment after biopsy and had Gleason score and PSA serum values obtained. The mean PSA value was 33.8 ± 40.9 nmol/L (range 2.2-232). RESULTS: Nineteen patients had extended disease (55.9%). The mean SUVmax in prostate lesions was 19.5 ± 12.6. The mean value of SUVmax of PET studies in the high-risk group was significantly higher than those of low risk (23.5 ± 13.2 and 10.6 ± 5.4, p < 0.05). A positive correlation was observed between the ISUP group and SUVmax value of prostate lesions (Pearson's r = 0.557, p < 0.01). A positive correlation was also found in the comparison between PSA values and SUVmax (Pearson's r = 0.34, p < 0.05). CONCLUSIONS: In our study, [68Ga]Ga-PSMA-11 PET/CT scans detected the extended disease in more than half of the patients. Locating disease beyond the prostate gland allowed better informed clinical decisions and modified treatment. A positive correlation was found between intraprostatic SUVmax values and the ISUP group of prostate cancer. High-risk patients had SUVmax values that were significantly higher than those of low-risk patients. The correlation between the Gleason score and SUVmax value can be explained by the increased intensity of PSMA expression as the tumor grade increases.

An Unexpected Seminal Vesicle Pitfall in PSMA PET.

ABSTRACT: A 76-year-old man undergoing hormone therapy for prostate cancer was referred for 68 Ga-PSMA-11-PET (PSMA PET) due to persistently detectable PSA level. No PSMA-positive tumor lesions were detected, so a delayed phase imaging was performed, which revealed focal PSMA uptake in the right seminal vesicle together with contrast accumulation on excretory phase contrast-enhanced CT. These findings were finally determined to be secondary to urinary reflux as a consequence of a prostatic enucleation he had undergone 5 months earlier following an episode of acute urinary retention.

The Value of 68Ga-PSMA PET/MRI for Classifying Patients with PI-RADS 3 Lesions on Multiparametric MRI: A Prospective Single-Center Study.

Prostate Imaging Reporting and Data System (PI-RADS) category 3 lesions remain a diagnostic challenge for detecting clinically significant prostate cancer (csPCa). This article evaluates the added value of 68Ga-labeled prostate-specific membrane antigen-11 (68Ga-PSMA) PET/MRI in classifying PI-RADS 3 lesions to avoid unnecessary biopsies. Methods: Sixty biopsy-naïve men with PI-RADS 3 lesions on multiparametric MRI were prospectively enrolled between February 2020 and October 2022. In all, 56 participants underwent 68Ga-PSMA PET/MRI and prostate systematic biopsy. 68Ga-PSMA PET/MRI was independently evaluated and reported by the 5-level PRIMARY score developed within the PRIMARY trial. Receiver-operating-characteristic curve analysis was used to estimate the diagnostic performance. Results: csPCa was detected in 8 of 56 patients (14.3%). The proportion of patients with csPCa and a PRIMARY score of 1, 2, 3, 4, and 5 was 0% (0/12), 0% (0/13), 6.3% (1/16), 38.5% (5/13), and 100% (2/2), respectively. The estimated area under the curve of the PRIMARY score was 0.91 (95% CI, 0.817-0.999). For a PRIMARY score of 4-5 versus a PRIMARY score of 1-3, the sensitivity, specificity, positive predictive value, and negative predictive value were 87.5%, 83.3%, 46.7%, and 97.5%, respectively. With a PRIMARY score of at least 4 to make a biopsy decision in men with PI-RADS 3 lesions, 40 of 48 patients (83.3%) could avoid unnecessary biopsies, at the expense of missing 1 of 8 (12.5%) csPCa cases. Conclusion: 68Ga-PSMA PET/MRI has great potential to classify patients with PI-RADS 3 lesions and help avoid unnecessary biopsies.

Comparison of Ga-PSMA PET MRI with mpMRI in localization and regional staging of prostate cancer.

PURPOSE: To compare diagnostic accuracy in localization and detection of extraprostatic extension (EPE), seminal vesicle invasion (SVI), lymph node involvement (LNI) between PSMA PET MRI and multiparametric MRI (mpMRI) in carcinoma prostate. METHODS: We did a prospective study of consecutive men with biopsy-proven prostate cancer who underwent radical prostatectomy between July'2020 and Dec'2021 at our institution. Patients underwent PSMA PET MRI imaging. MpMRI findings were inferred separately by another radiologist who was blinded to the PSMA PET findings. PIRADS > 2 and any standardized uptake value (SUV) were considered positive. Findings were mapped to a 30-region anatomical grid and compared with pathology. The uro-pathologist also marked the presence of the tumor onto the same anatomical grid. The presence of EPE, SVI, and LVI was noted. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The significance in difference: McNemar test. SUVmax and Gleason score: Kruskal-Wallis test. RESULTS: Seventy-five men (mean age 65) with an average PSA of 21.5 ng/ml were included. The sensitivity of PSMA PET MRI for localization was higher [63.6 vs 41.9] (p < 0.001) while specificity was similar [81.5 vs 83.2] (p 0.103). The former had a higher sensitivity to detect SVI [85.7 vs 57.10] (p = 0.03). No difference in the detection of EPE or LNI was noted. SUVmax > 7 was associated with high-risk disease (Gleason score >/= 7). LIMITATIONS: non-randomized nature, higher risk population. CONCLUSION: Ga-PSMA PET MRI improved the localization of prostate cancer and better detection of SVI. Further studies are required. It can act as a single-stop investigation for the primary staging of prostate cancer.

Potential of PSMA-targeting radioligand therapy for malignant primary and secondary brain tumours using super-selective intra-arterial administration: a single centre, open label, non-randomised prospective imaging study.

BACKGROUND: The aim of this study was to provide quantitative evidence for the potential of PSMA-targeting radioligand therapy (RLT) as treatment approach for malignant brain tumours, and to explore whether tumour uptake could be enhanced by super-selective intra-arterial (ssIA)-administration. METHODS: Ten patients (n = 5 high-grade glioma, n = 5 brain metastasis) received 1.5 MBq/kg [68Ga]Ga-PSMA-11 intravenously and, within 7 days, intra-arterially (i.e., selectively in tumour-feeding arteries), followed twice by PET-MRI at 90, 165 and 240 min post-injection. Patient safety was monitored for each procedure. Standardised uptake values (SUVs) were obtained for tumour, healthy-brain, salivary glands and liver. Tumour-to-salivary-gland (T/SG) and tumour-to-liver (T/L) uptake-ratios were calculated. FINDINGS: No adverse events requiring study termination occurred. All patients showed uptake of [68Ga]Ga-PSMA-11 at the tumour site. Uptake was a median 15-fold higher following ssIA-administration (SUVmax median: 142.8, IQR: 102.8-245.9) compared to IV-administration (10.5, IQR:7.5-13.0). According to the bootstrap analysis, mean SUVmax after ssIA (168.8, 95% CI: 110.6-227.0) was well beyond the 95% confidence-interval of IV administration (10.5, 95% CI: 8.4-12.7). Uptake in healthy-brain was negligible, independent of administration route (SUVmean <0.1-0.1). Off-target uptake was comparable, resulting in more favourable T/SG- and T/L-ratios of 8.4 (IQR: 4.4-11.5) and 26.5 (IQR: 14.0-46.4) following ssIA, versus 0.5 (IQR: 0.4-0.7) and 1.8 (IQR: 1.0-2.7) for IV-administration. INTERPRETATION: ssIA-administration is safe and leads to a median fifteen-fold higher radioligand uptake at the tumour site, therewith qualifying more patients for treatment and enhancing the potential of therapy. These results open new avenues for the development of effective RLT-based treatment strategies for patients with brain tumours. FUNDING: Semmy Foundation.

18F-FDG and 68Ga-PSMA PET/CT in Paratesticular Mesothelioma.

ABSTRACT: A 66-year-old man with local prostate adenocarcinoma underwent radical prostatectomy (Gleason score 3 + 4 = 7, pT2c) in 2016. Four years later, he presented with a hydrocele and cystic atypical change in the left scrotum and soft tissue in the left groin. Final histopathology revealed spermatic cord mesothelioma and left hemangiosis carcinomatosa. A bone biopsy of the sacrum revealed infiltrates of a prostatic adenocarcinoma with small cell neuroendocrine differentiation. Dual-tracer PET/CT imaging using 18F-FDG and 68Ga-PSMA was able to identify local recurrence of scrotal mesothelioma and differentiate metastases of prostate cancer from malignant mesothelioma.

A Hangover Under 177 Lu-PSMA-617 Therapy : A Red Flag for Brain 68 Ga-PSMA-11 PET/MRI?

ABSTRACT: Leptomeningeal carcinomatosis in prostate cancer is extremely rare. Because of the low overall penetration of drugs into the brain and the prolonged survival of castration-resistant prostate cancer (CRPC) patients, a special attention should be paid to the appearance of neurological symptoms in long-term CRPC survivors. A patient suffering from a CRPC with bone metastases underwent 4 cycles of 177 Lu-PSMA (prostate-specific membrane antigen)-617. Starting from the third cycle, he reported an increasing feeling of a permanent hangover. A 68 Ga-PSMA-11 brain PET/MRI was carried out after the fourth cycle. It revealed intraparenchymatous brain metastases with intense uptake and evidences of leptomeningeal carcinomatosis.

68 Ga-PSMA Uptake in the Testis : Two Different Patients With Two Different Diagnosis.

ABSTRACT: Although abnormal 68 Ga-PSMA uptake in the prostate and its metastases can be seen in a variety of diseases, it is rare to see in the testis. In these 2 cases, 68 Ga-PSMA PET/CT revealed unilateral 68 Ga-PSMA uptake in the testis of 2 patients. One of these patients was diagnosed with testis metastases from prostate cancer after an orchiectomy. The other patient was diagnosed with an orchitis. 68 Ga-PSMA uptake should be considered as an infection, as well as a malignancy in the initial differential diagnosis.

Correlation between pre-radical prostatectomy standardized SUVmax ratios detected on 68Ga-PSMA-I&T PET/CT and final histopathology outcomes: an in-depth analysis.

OBJECTIVE: To evaluate the predictive potential of the maximum standardized uptake value(SUVmax) value of intraprostatic tumors derived from preoperative 68Ga-PSMA-I&T PET/CT (SUVT), and its ratios to SUVmax in the liver (SUVTLR) and parotid gland (SUVTPR) with respect to histopathological findings. MATERIALS AND METHODS: Data from patients who underwent radical prostatectomy (RP) for prostate cancer (PC) at our clinic between 2017 and 2020 were assessed. Patients with a secondary malignancy, a history of transurethral prostate resection, prior treatment for PC, or who received salvage RP were excluded. Whole-body images obtained using the same device, as per the guidelines, were reviewed by two nuclear medicine specialists with more than a decade of experience to reach a consensus for each lesion. The relationships between age, PSA, Prostate Volume, clinical T stage, biopsy International Society of Urological Pathology grade (ISUP), D'amico risk group, intraprostatic tumor volume (HPTV) identified in the final histopathological specimen review, HP-ISUP grade, seminal vesicle invasion (SVI), extracapsular invasion (ECI), positive surgical margine (PSM), SUVT, SUVTLR, and SUVTPR were analyzed. RESULTS: The mean age of the 64 included patients was 64.1 ±â€¯5.3. A statistically significant correlation was found between SUVT, SUVTLR, SUVTPR values, and histopathologic stage parameters, such as biopsy ISUP, D'amico Risk Classification, HP-ISUP, HPTV (p < 0.05). PSMATV, SUVT, and SUVTLR were statistically significant predictors of extracapsular invasion, while PSA, PSMATV, and SUVTLR were significant predictors of SVI (p < 0.05). CONCLUSION: The standardized SUVT, SUVTLR, and SUVTPR values could be employed as noninvasive markers to assist in predicting postoperative histopathological findings, particularly ECI, SVI, and PSM.

Diagnostic accuracy of bone scan at different PSA levels in biochemical recurrence of prostate cancer.

OBJECTIVE: To determine the diagnostic accuracy of Bone Scan at different PSA levels for detecting skeletal metastases in men with biochemical recurrence of prostate cancer. METHODS: We conducted a retrospective review of the statewide RIS-PACS to identify 251 men with biochemical recurrence who underwent both a Bone Scan and Ga68 PSMA PET/CT (within 2 months of each other) between September 2019 and December 2022 at a single institution. The Ga68 PSMA PET/CT report was considered to be the reference standard. RESULTS: The median age was 72 years (IQR 67-76) with a median PSA level of 1 ng/ml (IQR 0.25-2.8). Using Ga68 PSMA PET/CT as the reference standard, 68/251 patients (25%) were positive for osseus metastases. Overall sensitivity and specificity of Bone Scan was 51% (95% CI 40-64%) and 99% (95% CI 98-100%) respectively. Using PSA banding, a PSA threshold of 20 ng/ml provided the greatest discriminatory benefit with sensitivity of the Bone Scan below the threshold being 46% (95% CI 33-59%) and above the threshold being 89% (95% CI 68-100%). Specificity remained consistently high both below and above this threshold. CONCLUSION: Bone Scan provides greater diagnostic accuracy for detecting skeletal metastases in biochemical recurrence when the PSA level is above 20 ng/ml. This knowledge is valuable in optimising imaging algorithms in biochemical recurrence, particularly in regions where PSMA PET/CT is less readily available or affordable.

[68 Ga]Ga-FAPI-46 PET/CT for locoregional lymph node staging in urothelial carcinoma of the bladder prior to cystectomy: initial experiences from a pilot analysis.

INTRODUCTION: [68 Ga]Ga-FAPI-46 PET/CT is a novel hybrid imaging method that previously showed additional diagnostic value in the assessment of distant urothelial carcinoma lesions. We hypothesized that patients with bladder cancer benefit from [68 Ga]Ga-FAPI-46 PET/CT prior to radical cystectomy for locoregional lymph node staging. MATERIALS AND METHODS: Eighteen patients underwent [68 Ga]Ga-FAPI-46 PET/CT for evaluation of lymph node (LN) status in predefined LN regions. Two hundred twenty-nine intraoperatively removed LN served as histopathological reference standard. RESULTS: Urothelial carcinoma (UC) spread was found in ten LN in seven different regions (14.3%). Hereby, [68 Ga]Ga-FAPI-46 PET/CT was positive in four out of seven regions (57.1%) and showed significantly increased FAPI uptake compared to non-pathological regions. In the remaining three out of seven (42.9%) regions, [68 Ga]Ga-FAPI-46 PET/CT was rated negative since no pathological increased FAPI uptake was detected or the proximity of the urinary tract prevented a differentiation from physiological uptake. CT was inconspicuous in these three regions. In total, two FAP-positive LN regions were found without histopathological counterpart. Overall, sensitivity, specificity, positive predictive value, and negative predictive value were 57.1%, 95.2%, 66.7%, and 93.0% for PET imaging. CONCLUSION: In summary, this innovative [68 Ga]Ga-FAPI-46 PET/CT method showed high specificity and negative predictive value in patients with bladder UC with a future potential to optimize therapy planning.

68 Ga-PSMA PET/CT Found Lower Respiratory Tract Inflammation Due to Inhaler Use.

ABSTRACT: Prostate-specific membrane antigen (PSMA) is a transmembrane protein physiologically expressed in nonprostatic tissues. Inflammation and infectious diseases could show false-positive PSMA uptake. Herein, we present a 55-year-old patient's findings of inflammation in the lower respiratory tract due to inhaler use in 68 Ga-PSMA PET/CT in a patient with prostate cancer.

Comparisons of mpMRI, 68Ga-PSMA PET/CT and mpMRI combined with 68Ga-PSMA PET/CT in diagnosing prostate cancer based on tumor detection, localization and staging.

PURPOSE: To evaluate the diagnostic ability of mpMRI, 68Ga-PSMA PET/CT and mpMRI combined with 68Ga-PSMA PET/CT in detecting and localizing lesions, and further clarify the accuracy of these examinations in tumor staging. METHODS: Seventy patients who underwent mpMRI, 68Ga-PSMA PET/CT and radical prostatectomy were enrolled. The abilities to detect index and clinically significant lesions by three examinations were compared. We further evaluated the ability of these examinations to localize lesions to the superior, inferior, anterior, posterior, left and right halves of the prostate and analyzed their accuracy in local and lymph node staging. RESULTS: There were no significant differences among mpMRI, 68Ga-PSMA PET/CT and mpMRI combined with 68Ga-PSMA PET/CT in their ability to detect index (p = 0.48, p = 0.23 and p = 0.07) and clinically significant lesions (p = 0.30, p = 0.29 and p = 0.06) or to localize lesions in six half divisions of the prostate. With postoperative pathology as reference, both mpMRI (p = 0.10) and mpMRI combined with 68Ga-PSMA PET/CT (p = 0.10) can accurately assess the local staging of prostate cancer. However, 68Ga-PSMA PET/CT underestimates the local staging of prostate cancer (p < 0.01). Regarding lymph node staging, the three types of examination showed no significant differences compared to postoperative pathology (p = 0.63, p = 0.51 and p = 0.14). CONCLUSIONS: With postoperative pathology as reference, 68Ga-PSMA PET/CT underestimates the local tumor staging. MpMRI combined with 68Ga-PSMA PET/CT has no obvious advantages in detecting, localizing or staging prostate cancer compared with mpMRI.

Incidental Prostate-Specific Membrane Antigen-Avid Vestibular Schwannoma Detected on 68 Ga-Prostate-Specific Membrane Antigen PET/CT.

ABSTRACT: A 62-year-old man was referred for a 68 Ga-prostate-specific membrane antigen (PSMA) PET/CT scan for newly diagnosed prostate cancer (ISUP grade 5), on the background of left vestibular schwannoma treated with surgical excision 25 years ago. PSMA PET study confirmed the presence of PSMA-avid malignancy in the left prostate lobe with no evidence of PSMA-avid nodal or distant metastasis. An incidental PSMA-avid focus (SUV max , 4.3) was identified in the region of the left cerebellopontine angle, which corresponded to a homogeneous enhancing lesion centered at the left internal acoustic canal and left cerebellopontine angle on MRI. The combined PSMA PET findings and MRI characteristics were consistent with recurrent vestibular schwannoma.