68Ga-PSMA-11 PET/CT in Newly Diagnosed Prostate Adenocarcinoma

Preliminary clinical practice of radical prostatectomy without preoperative biopsy

BACKGROUND

At present, biopsy is essential for the diagnosis of prostate cancer (PCa) before radical prostatectomy (RP). However, with the development of prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA PET/CT) and multiparametric magnetic resonance imaging (mpMRI), it might be feasible to avoid biopsy before RP. Herein, we aimed to explore the feasibility of avoiding biopsy before RP in patients highly suspected of having PCa after assessment of PSMA PET/CT and mpMRI.

METHODS

Between December 2017 and April 2022, 56 patients with maximum standardized uptake value (SUVmax) of ≥4 and Prostate Imaging Reporting and Data System (PI-RADS) ≥4 lesions who received RP without preoperative biopsy were enrolled from two tertiary hospitals. The consistency between clinical and pathological diagnoses was evaluated. Preoperative characteristics were compared among patients with different pathological types, T stages, International Society of Urological Pathology (ISUP) grades, and European Association of Urology (EAU) risk groups.

RESULTS

Fifty-five (98%) patients were confirmed with PCa by pathology, including 49 (89%) with clinically significant prostate cancer (csPCa, defined as ISUP grade ≥2 malignancy). One patient was diagnosed with high-grade prostatic intraepithelial neoplasia (HGPIN). CsPCa patients, compared with clinically insignificant prostate cancer (cisPCa) and HGPIN patients, were associated with a higher level of prostate-specific antigen (22.9 ng/mL vs. 10.0 ng/mL, P = 0.032), a lower median prostate volume (32.2 mL vs. 65.0 mL, P = 0.001), and a higher median SUVmax (13.3 vs. 5.6, P <0.001).

CONCLUSIONS

It might be feasible to avoid biopsy before RP for patients with a high probability of PCa based on PSMA PET/CT and mpMRI. However, the diagnostic efficacy of csPCa with PI-RADS ≥4 and SUVmax of ≥4 is inadequate for performing a procedure such as RP. Further prospective multicenter studies with larger sample sizes are necessary to confirm our perspectives and establish predictive models with PSMA PET/CT and mpMRI.

Bilateral Adrenal Metastasis of Prostatic Adenocarcinoma on 68 Ga-PSMA PET/CT Imaging

ABSTRACT

An 84-year-old man with prostate adenocarcinoma underwent 68 Ga-PSMA PET/CT due to PSA recurrence. Foci of 68 Ga-PSMA uptake were observed in bilateral adrenal glands. Adrenal MRI showed metastasis only in the left adrenal gland. Metastatic 68 Ga-PSMA uptake was also observed in the mediastinum and bone. Enzalutamide treatment was started. Follow-up 68 Ga-PSMA PET/CT scan showed regression in both adrenal gland metastases and other metastases.

Contribution of 68 Ga-DOTA-FAPI-04 PET/CT to Prostate Cancer Imaging : Complementary Role in PSMA-Negative Cases

PURPOSE

Prostate-specific membrane antigen (PSMA)-targeted PET/CT is a well-established imaging method in prostate cancer (PC) for both staging and restaging, and also for theranostic applications. An alternative imaging method is crucial for 15% PSMA-negative cases. We aimed to investigate the contribution of 68 Ga-DOTA-FAPI-04 PET/CT to PC imaging.

PATIENTS AND METHODS

Thirty-six patients diagnosed with PC were included. Patients underwent both 68 Ga-PSMA PET/CT and 68 Ga-DOTA-FAPI-04 PET/CT imaging within 1 week. In staging group, primary tumor uptake values were compared, and also correlations were done with histopathological findings, MRI findings, and total PSA levels. In biochemical recurrence group, the uptake values in prostatic region and metastases were evaluated to define the local recurrence or metastatic disease.

RESULTS

In staging group, PSMA PET showed increased uptake in the primary lesion area in 14/27 (52%) patients, whereas 20/27 (74%) patients were positive in FAPI-04 PET. FAPI-04 positivity was found to be quite high, such as 54%, in PSMA-negative patients. A significant difference was observed between ISUP grade 1-3 patients and ISUP grade 4-5 patients in FAPI-04 PET ( P = 0.03). Local recurrence was detected in 3 patients, pelvic lymph node metastasis in 1 patient, and sacrum metastasis in 1 patient in biochemical recurrence group, and all of the lesions had more intense uptake in PSMA PET than FAPI-04 PET.

CONCLUSIONS

FAPI PET imaging seems to have a potential to contribute PSMA PET imaging with FAPI positivity in more than half of PSMA-negative cases. Also, FAPI-targeted radionuclide therapy may be a promising method in patients resistant to PSMA-targeted therapy.

[99mTc]Tc-HYNIC-ALUG SPECT/CT in the initial staging of 227 consecutive patients with newly diagnosed prostate cancer: a 5-year monocentric retrospective study

Purpose

The purpose of this study was to assess the effectiveness of [99mTc]Tc-HYNIC-ALUG SPECT/CT in the initial staging of patients with newly diagnosed PCa.

Methods

A retrospective analysis was conducted on 227 consecutive patients who underwent [99mTc]Tc-HYNIC-ALUG SPECT/CT imaging for the primary staging of newly diagnosed PCa. The presence and location of PSMA-positive lesions were determined, and the maximum standardized uptake values (SUVmax) of the primary prostate tumor were also measured. The metastatic findings and SUVmax were stratified according to International Society of Urological Pathology (ISUP) grade, prostate-specific antigen (PSA) levels, and D'Amico classification. Furthermore, the [99mTc]Tc-HYNIC-ALUG SPECT/CT findings were compared to the histopathological findings in patients who had undergone radical prostatectomy with pelvic lymph node dissection (PLND).

Results

Of the 227 patients, 92.1% (209/227) had positive [99mTc]Tc-HYNIC-ALUG SPECT/CT findings. Advanced disease was detected in 38.8% (88/227) of the patients and was positively correlated with increasing ISUP grade and PSA levels. Lymph node metastases (both pelvic and extrapelvic), bone metastases, and visceral metastases were detected in 30.0% (68/227), 25.6% (58/227), and 3.1% (7/227) of the patients, respectively. For the 129 patients who underwent radical prostatectomy with PLND, the sensitivity of [99mTc]Tc-HYNIC-ALUG SPECT/CT in the evaluation of PCa was 90.7% (117/129). The sensitivity, specificity, accuracy, and positive and negative predictive values for detecting pelvic lymph node metastases on [99mTc]Tc-HYNIC-ALUG SPECT/CT were 23.5% (12/51), 93.6% (73/78), 65.9% (85/129), 70.6% (12/17), and 65.2% (73/112), respectively. Among the 209 patients with PSMA-avid primary prostate disease, the SUVmax of the primary prostate tumor was significantly associated with ISUP grade (p<0.0001), PSA levels (p<0.0001), D'Amico classification (p<0.0001), and advanced disease (p<0.0001). Receiver operating characteristic (ROC) analysis revealed that a PSA level >19.8 ng/ml and SUVmax of the primary prostate tumor >7.4 had a sensitivity of 71.6% and 71.6% and specificity of 76.9% and 82.6%, respectively, for detecting metastatic disease.

Conclusions

[99mTc]Tc-HYNIC-ALUG SPECT/CT emerges as a valuable imaging tool for the initial staging of newly diagnosed PCa. The presence of advanced disease and the SUVmax of the primary prostate tumor were positively correlated with ISUP grade and PSA levels.

Noninvasive Verification of a Very Small Intraocular Prostate Carcinoma Metastasis by 68Ga-PSMA-11 PET/CT

ABSTRACT

A male patient underwent 68Ga-PSMA-11 PET/CT for the evaluation of a suspected intraocular metastasis in the right eye. Although the choroidal thickening was very small (4 × 2 mm), and ophthalmoscopy as well as MRI were inconclusive, PET/CT imaging showed distinct PSMA expression in the suspected lesion, confirming prostate cancer metastasis. The ability of dedicated PSMA ligand PET/CT imaging to detect small metastases, even with 68Ga-labeled ligands, has been demonstrated. Therefore, the use of further invasive diagnostic procedures could be avoided. Thus, the possibility of detecting intraocular metastases of prostate cancer should be considered in routine PET/CT imaging.

Improving diagnostic efficacy of primary prostate cancer with combined 99mTc-PSMA SPECT/CT and multiparametric-MRI and quantitative parameters

Purpose

This prospective study aimed to evaluate the difference between 99mTc-PSMA single-photon emission computed tomography (SPECT)/CT and multiparametric magnetic resonance imaging (mpMRI) in the detection of primary prostate cancer (PCa).

Materials and methods

Fifty-six men with suspected PCa between October 2019 and November 2022 were prospectively enrolled in this study. The median age of the patients was 70 years (range, 29-87 years). Patients were divided into high-(Gleason score>7, n=31), medium- (Gleason score=7, n=6) and low-risk groups (Gleason score < 7, n=6). All patients underwent 99mTc-PSMA SPECT/CT and mpMRI at an average interval of 3 days (range, 1-7 days). The maximum standardized uptake value (SUVmax), the minimum apparent diffusion coefficient (ADCmin), and their ratio (SUVmax/ADCmin) were used as imaging parameters to distinguish benign from malignant prostatic lesions.

Results

Of the 56 patients, 12 were pathologically diagnosed with a benign disease, and 44 were diagnosed with PCa. 99mTc-PSMA SPECT/CT and mpMRI showed no significant difference in the detection of primary PCa (kappa =0.401, P=0.002), with sensitivities of 97.7% (43/44) and 90.9% (40/44), specificities of 75.0% (9/12) and 75.0% (9/12), and AUC of 97.4% and 95.1%, respectively. The AUC of SUVmax/ADCmin was better than those of SUVmax or ADCmin alone. When SUVmax/ADCmin in the prostatic lesion was >7.0×103, the lesion was more likely to be malignant. When SUVmax/ADCmin in the prostatic lesion is >27.0×103, the PCa patient may have lymph node and bone metastases. SUVmax was positively correlated with the Gleason score (r=0.61, P=0.008), whereas ADCmin was negatively correlated with the Gleason score (r=-0.35, P=0.023). SUVmax/ADCmin was positively correlated with the Gleason score (r=0.59, P=0.023). SUVmax/ADCmin was the main predictor of the high-risk group, with an optimal cut-off value of 15.0×103.

Conclusions

The combination of 99mTc-PSMA SPECT/CT and mpMRI can improve the diagnostic efficacy for PCa compared with either modality alone; SUVmax/ADCmin is a valuable differential diagnostic imaging parameter.

New perspectives on metabolic imaging in the management of prostate cancer in 2022: A focus on radiolabeled PSMA‑PET/CT (Review)

Nuclear medicine is an essential part of prostate cancer management concerning initial staging, patient follow-up and even therapy. Prostate-specific membrane antigen (PSMA) is a glutamate carboxypeptidase II transmembrane glycoprotein expressed by 80% of prostatic cells. The interest in this protein is due to its specificity for prostatic tissue. The use of 68GaPSMA PET/CT in the context of disease staging is thus well-established and recommended, especially for high-risk disease with metastases and lymph node involvement. However, the risk of false positives raises questions regarding its place in the management of patients with prostate cancer. The present study aimed to determine the use of PET-PSMA in the care of patients with prostate cancer but also to assess its limits of use.

Preoperative evaluation of prostate cancer by 68Ga-PMSA positron emission tomography/computed tomography: comparison with magnetic resonance imaging and with histopathological findings

Objective

To evaluate the accuracy of preoperative positron emission tomography/computed tomography with 68Ga-labeled prostate-specific membrane antigen (68Ga-PSMA PET/CT) for staging prostate cancer and compare it with magnetic resonance imaging (MRI) using histopathology of surgical specimens as the gold standard.

Materials and Methods

In this retrospective study, 65 patients with prostate cancer were analyzed.

Results

The accuracy of 68Ga-PSMA PET/CT for tumor detection was 95%, and that of MRI was 91%. There was no difference between 68Ga-PSMA PET/CT and MRI regarding localization of the lesion. The sensitivity of 68Ga-PSMA PET/CT for detecting extraprostatic extension was quite low (14%). For detection of seminal vesicle invasion, 68Ga-PSMA PET/CT showed a sensitivity of 57% and accuracy of 91%. There was a moderate correlation between the maximum standardized uptake value (SUVmax) and the serum level of prostate-specific antigen (p < 0.01; ρ = 0.368) and between the SUVmax and the International Society of Urological Pathology (ISUP) grade (p < 0.01; ρ = 0.513).

Conclusion

68Ga-PSMA PET/CT is a promising tool for detecting and evaluating the primary tumor, which can alter the staging and management of the disease.

Status of 18F-PSMA-1007-PET/CT compared with multiparametric MRI in preoperative evaluation of prostate cancer

PURPOSE

Treatment of primary prostate cancer extremely depends on preoperative stage. The role of ¹⁸F-1007-PSMA-PET/CT in preoperative staging has not been well defined. Our aim was to compare the diagnostic performance of ¹⁸F-1007-PEMA-PET/CT, mpMRI, and mpMRI + PEMA-PET/CT in local progression and lymph node invasion of prostate cancer using histopathology as the gold standard.

MATERIALS AND METHODS

In this retrospective study, all patients with prostate cancer who underwent mpMRI and ¹⁸F-PSMA-1007-PET/CT before operation were included. The role of preoperative imaging was evaluated by predicting the sensitivity and specificity of EPE (extraprostatic extension), SVI (seminal vesicle invasion), and lymph node invasion results.

RESULTS

Ultimately, 130 patients were included in this study. In the preoperative judgment of EPE and SVI, mpMRI + PSMA-PET/CT had higher sensitivity and specificity. When predicting lymph node metastasis, PSMA-PET/CT was the best choice. The accuracy of mpMRI + PSMA-PET/CT and PSMA-PET/CT in the T and N stages, respectively, was affected by the least factors.

CONCLUSIONS

Based on the combined results of mpMRI and ¹⁸F-1007-PSMA-PET/CT, the accuracy of the preoperative judgment of prostatic capsule invasion can be improved, which may be conducive to developing intra-fascial technology while ensuring no tumor-touch isolation. PSMA-PET/CT has the advantages over mpMRI alone in terms of lymph node positivity. Compared with PSMA-PET/CT alone, the combined results can improve the sensitivity, but reduce specificity. Therefore, it is recommended to focus on PSMA-PET/CT to decide whether lymph node dissection should be performed.

18F-PSMA-1007 PET/CT-derived semi-quantitative parameters for risk stratification of newly diagnosed prostate cancer

Purpose

This study aimed to assess the value of ¹⁸F-PSMA-1007 positron emission tomography/computed tomography (PET/CT)-derived semi-quantitative parameters of primary tumor for risk stratification of newly diagnosed prostate cancer (PCa).

Methods

Sixty patients referred for ¹⁸F-PSMA-1007 PET/CT imaging for primary PCa were retrospectively analyzed and classified into the low-intermediate-risk (LIR) or high-risk (HR) group. The maximum standardized uptake value (SUVmax) of primary tumor, prostate total lesion PSMA (TL-PSMAp), and prostate PSMA-tumor volume (PSMA-TVp) were measured, and group differences were evaluated using the Mann-Whitney U test. Spearman's correlation was performed to assess the correlation between the above parameters with prostate-specific antigen (PSA) levels and Gleason score (GS). Receiver operating characteristic (ROC) curve analysis was used to determine optimal cut-off values for SUVmax, TL-PSMAp, and PSMA-TVp to identify high-risk PCa and compare diagnostic efficacy.

Results

Among 60 patients, 46 were assigned to the HR group and 16 to the LIR group. In all patients, SUVmax, TL-PSMAp, and PSMA-TVp were moderately correlated with pre-treatment PSA values (r = 0.411, p = 0.001; r = 0.663, p < 0.001; and r = 0.549, p < 0.001, respectively). SUVmax and TL-PSMAp were moderately correlated with GS (r = 0.457 and r = 0.448, respectively; p < 0.001), while PSMA-TVp was weakly correlated with GS (r = 0.285, p = 0.027). In the ROC curve analysis, the optimal cut-off values of SUVmax, TL-PSMAp, and PSMA-TVp for identifying high-risk PCa were 9.61, 59.62, and 10.27, respectively, and the areas under the operating curve were 0.828, 0.901, and 0.809, respectively. The sensitivities of SUVmax, TL-PSMAp, and PSMA-TVp were 91.03%, 71.74%, and 63.04%, respectively, and the specificities were 71.43%, 100.00%, and 92.86%, respectively.

Conclusions

TL-PSMAp had a superior ability to identify high-risk PCa. The semi-quantitative parameters of primary tumor on ¹⁸F-PSMA-1007 PET/CT imaging can be an objective imaging reference index to determine PCa risk stratification.

Comparison of 68Ga-PSMA PET/CT and multiparametric MRI for the detection of low- and intermediate-risk prostate cancer

Purpose

To assess ⁶⁸Ga-PSMA PET/CT for detection of low- and intermediate-risk prostate cancer (PCa), high-risk PCa in comparison with mpMRI, respectively, and to determine which of low- and intermediate-risk PCa are more likely to be detected by ⁶⁸Ga-PSMA PET/CT.

Methods

We conducted a retrospective analysis of patients who had undergone a prostate biopsy and/or radical prostatectomy and who were scanned with ⁶⁸Ga-PSMA PET/CT and mpMRI between June 2019 and March 2021. The mpMRI images were scored with the Prostate Imaging-Reporting and Data System Version 2.1 (PI-RADS) and were classified as either negative (PI-RADS 1–3) or positive (PI-RADS 4–5). Suspicious ⁶⁸Ga-PSMA PET/CT lesions were reviewed for each relevant patient and classified by double-trained board-certified nuclear medicine physicians. The results were evaluated with the histopathological outcome. All patients were classified according to the D’Amico classification, and the clinical data were combined for stratified analysis.

Result

A total of 101 patients who were pathologically diagnosed with PCa were analyzed. Of the 101 patients, 88 (80.6%) patients presented with a pathologic mpMRI, and 85 (79.1%) with a pathologic ⁶⁸Ga-PSMA PET/CT. In the high-risk PCa cohort, ⁶⁸Ga-PSMA PET/CT was positive in 64/66 (97.0%) patients and yielded a higher detection rate than that for the mpMRI patients (58/66, 87.9%; p < 0.05). However, mpMRI provided superior diagnostic confidence in identifying low- and intermediate-risk PCa (30/35, 85.7% vs. 21/35, 60.0%; p < 0.05). When the age threshold exceeded 62.5 years and the serum prostate specific antigen (PSA) threshold exceeded 9.4 ng/ml, a higher uptake of PSMA was more likely to occur in the lesions of low- and intermediate-risk PCa.

Conclusion

The diagnostic performance of ⁶⁸Ga-PSMA PET/CT was superior to that of mpMRI in the high-risk PCa cohort, which was consistent with prior studies. Furthermore, in the initial diagnosis of low- and intermediate-risk PCa, we found that mpMRI showed a higher diagnostic accuracy than ⁶⁸Ga-PSMA PET/CT did. Low- and intermediate-risk PCa patients with a PSA ≥ 9.4 ng/ml and age ≥ 62.5 years were more likely to have a positive ⁶⁸Ga-PSMA PET/CT result.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13550-022-00881-3.

Targeted fluorescent imaging of a novel FITC-labeled PSMA ligand in prostate cancer

In this study, we synthesized a novel fluorescein isothiocyanate (FITC)-labeled prostate-specific membrane antigen (PSMA) ligand (PSMA-FITC) via the Fmoc solid-phase synthesis method, and the application value of PSMA-FITC in targeted fluorescence imaging of PSMA-positive prostate cancer was evaluated. The PSMA ligand developed based on the Glu-urea-Lys structure was linked to FITC by aminocaproic acid (Ahx) to obtain PSMA-FITC. The new probe was evaluated in vitro and in vivo. Fluorescence microscopy examination of PSMA-FITC in PSMA(+) LNCaP cells, PSMA(−) PC3 cells, and blocked LNCaP cells showed that the binding of PSMA-FITC with PSMA was target-specific. For in vivo optical imaging, PSMA-FITC exhibited rapid 22Rv1 tumor targeting within 30 min of injection, and the highest tumor-background ratio (TBR) was observed 60 min after injection. The TBR was 3.45 ± 0.31 in the nonblocking group and 0.44 ± 0.13 in the blocking group, which was consistent with the in vitro results. PSMA-FITC is a promising probe and has important reference value for the development of PSMA fluorescent probes. In the future, it can be applied to obtain accurate tumor images for radical prostatectomy.

Is SUV Corrected for Lean Body Mass Superior to SUV of Body Weight in 68Ga-PSMA PET/CT?

Objectives:

This study aimed to investigate the relationship between the standard uptake value (SUV) of body weight and SUV corrected for lean body mass (SUL) parameters obtained from the prostate gland in gallium-68 (⁶⁸Ga)-prostate-specific membrane antigen (PSMA) positron emission tomography-computed tomography (PET/CT) with Gleason grade (GG) groups, D’Amico risk groups, and presence of metastases.

Methods:

Patients with prostate adenocarcinoma who underwent ⁶⁸Ga-PSMA PET/CT for staging at our center between February 2017 and October 2018 were evaluated retrospectively. Maximum SUV (SUV_max), SUV_peak, SUL_max, SUL_peak, SUV_mean, and SUL_mean values of the prostate tumor were obtained. The difference in these values between GG groups (≥3, <3) and D’Amico risk (low-moderate/high) groups was evaluated with the Mann-Whitney U test. The area under the curve values of SUV and SUL parameters were compared. In addition, SUV_mean and SUL_mean values were obtained from the right liver lobe, and their correlation with body weight was evaluated.

Results:

A total of 79 patients were included in the study. Significant differences were found in the prostate SUV_max, SUL_max, SUV_peak, SUL_peak, SUV_mean, and SUL_mean values between the GG (≥3 and <3) groups and between D’Amico risk (low-moderate and high) groups. However, no significant difference was found in the discriminative power of any SUV or SUL parameter when compared with each other. A significant difference in any SUV and SUL parameters was found in patients with and without metastasis. Neither liver SUV_mean value nor SUL_mean value correlated with the body weight.

Conclusion:

The superiority of SUL values obtained from ⁶⁸Ga-PSMA PET to SUV was not determined in our study. SUV parameters can also be used for quantitative analysis in ⁶⁸Ga-PSMA PET.

Concomitant Prostate Cancer and Hodgkin Lymphoma: A Differential Diagnosis Guided by a Combined 68Ga-PSMA-11 and 18F-FDG PET/CT Approach

Here we report the case of concomitant favorable-risk prostate cancer and Hodgkin Lymphoma in a 38-year old male. 68Ga-Prostate Specific Membrane Antigen-11 Positron Emission Tomography/Computed Tomography (68Ga-PSMA-11 PET/CT) was performed for staging purposes, showing the focal PSMA prostatic uptake as well as the presence of enlarged low-PSMA expressing mediastinal lymphadenopathies, thus raising the suspicion of another malignancy. A subsequent 18F-Fluorodeoxyglucose (18F-FDG) PET/CT demonstrated a high FDG-avidity by mediastinal lymphadenopathies as opposed to the low prostate cancer FDG uptake. Of note, both tumor entities were clearly detected by the two scans. However, different ranges in terms of Maximum Standardized Uptake Value (SUVmax) uptake allowed the discrimination between the two tumor entities. At the subsequent mediastinal lymph nodal biopsy, the coexistence of Hodgkin lymphoma was documented. The present case suggests that even if specific for prostate cancer, 68Ga-PSMA-11 PET/CT may raise the suspicion of other concurrent malignancies thanks to its non-receptor bounding mechanism. Further, it shows that in certain cases, the combination of 18F-FDG and 68Ga-PSMA PET/CT imaging may non-invasively guide the clinical management, optimizing the diagnostic process and the subsequent therapeutic interventions.

Is there a utility of adding skeletal imaging to 68-Ga-prostate-specific membrane antigen-PET/computed tomography in initial staging of patients with high-risk prostate cancer?

PURPOSE

Both bone-scan and cross-sectional imaging are indicated in the staging of high-risk prostate cancer (PCa). However, 68Ga-prostate-specific membrane antigen (PSMA)-PET/computed tomography (CT) has proven to be an excellent tracer for detection of skeletal metastases. The aim of this study was to assess if adding skeletal imaging (with 18F-Fluoride-PET/CT) to 68-Ga-PSMA-PET/CT had any impact on high-risk PCa staging.

METHOD

Fifty treatment-naive, histopathologically proven, high-risk (European Association of Urology) PCa patients underwent both 68-Ga-PSMA-PET/CT and 18F-Fluoride-PET/CT for staging.

RESULTS

Fluoride-PET/CT detected significantly a higher number of skeletal metastases/patient than PSMA-PET/CT (median 4.5/patient vs 3.0; Wilcoxan-signed-rank-test, P = 0.060) and there was a significantly higher proportion of only Fluoride-avid than only PSMA-avid lesions (McNemar-test P < 0.001). No significant advantage was seen in patient-wise metrics. Most lesions missed by PSMA-PET/CT were in flat bones (25/33). serum prostate specific antigen (S.PSA) showed positive correlation with both, the number of lesions [r(PSMA)-0.555 (P = 0.006) and r(Fluoride)-0.622 (P = 0.001)] as well as tumor to background ratio (TBR) [[r-0.706 (P < 0.001) and 0.516 (P = 0.010)]. Median TBR was significantly higher in PSMA-PET/CT (22.77 vs 16.30; P < 0.001). All three patients with only Fluoride-avid lesions (also not identified in bone-scan) showed biochemical response with additional therapy.

CONCLUSION

Though, Fluoride-PET/CT detected a higher absolute number of lesions than PSMA-PET/CT, no significant advantage was seen in patient-wise metrics. Fluoride-PET/CT added second-line management in only 3/50 patients, which could have been reduced to 1/50, with more sensitive evaluation of flat bones in PSMA-PET-CT. Therefore, additional skeletal imaging is not needed with 68-Ga-PSMA-PET/CT in initial staging of high-risk PCa.

68Ga-Prostate-specific membrane antigen (psma) positron emission tomography (pet) in prostate cancer: a systematic review and meta-analysis

Introduction:

Prostate cancer (PC) is the second most commonly diagnosed cancer in males. ⁶⁸Ga-PSMA PET/CT, a non-invasive diagnostic tool to evaluate PC with prostate-specific membrane antigen (PSMA) expression, has emerged as a more accurate alternative to assess disease staging. We aimed to identify predictors of positive ⁶⁸Ga-PSMA PET and the accuracy of this technique.

Materials and methods:

Diagnostic accuracy cross-sectional study with prospective and retrospective approaches. We performed a comprehensive literature search on PubMed, Cochrane Library, and Embase database in search of studies including PC patients submitted to radical prostatectomy or radiotherapy with curative intent and presented biochemical recurrence following ASTRO 1996 criteria. A total of 35 studies involving 3910 patients submitted to 68-Ga-PSMA PET were included and independently assessed by two authors: 8 studies on diagnosis, four on staging, and 23 studies on restaging purposes. The significance level was α=0.05.

Results:

pooled sensitivity and specificity were 0.90 (0.86-0.93) and 0.90 (0.82-0.96), respectively, for diagnostic purposes; as for staging, pooled sensitivity and specificity were 0.93 (0.86-0.98) and 0.96 (0.92-0.99), respectively. In the restaging scenario, pooled sensitivity and specificity were 0.76 (0.74-0.78) and 0.45 (0.27-0.58), respectively, considering the identification of prostate cancer in each described situation. We also obtained specificity and sensitivity results for PSA subdivisions.

Conclusion:

⁶⁸Ga-PSMA PET provides higher sensitivity and specificity than traditional imaging for prostate cancer.

The Establishment of New Thresholds for PLND-Validated Clinical Nomograms to Predict Non-Regional Lymph Node Metastases: Using 68Ga-PSMA PET/CT as References

Purpose

PLND (pelvic lymph node dissection)-validated nomograms are widely accepted clinical tools to determine the necessity of PLND by predicting the metastasis of lymph nodes (LNMs) in pelvic region. However, these nomograms are in lacking of a threshold to predict the metastasis of extrareolar lymph nodes beyond pelvic region, which is not suitable for PLND. The aim of this study is to evaluate a threshold can be set for current clinical PLND-validated nomograms to predict extrareolar LN metastases beyond pelvic region in high-risk prostate cancer patients, by using ⁶⁸Ga-PSMA PET/CT as a reference to determine LN metastases (LNMs).

Experimental Design

We performed a retrospective analysis of 57 high-risk treatment-naïve PC patients in a large tertiary care hospital in China who underwent ⁶⁸Ga-PSMA-617 PET/CT imaging. LNMs was detected by ⁶⁸Ga-PSMA-617 PET/CT and further determined by imaging follow-up after anti-androgen therapy. The pattern of LN metastatic spread of PC patients were evaluated and analyzed. The impact of ⁶⁸Ga-PSMA PET/CT on clinical decisions based on three clinical PLND-validated nomograms (Briganti, Memorial Sloan Kettering Cancer Center, Winter) were evaluated by a multidisciplinary prostate cancer therapy team. The diagnostic performance and the threshold of these nomograms in predicting extrareolar LNMs metastasis were evaluated via receiver operating characteristic (ROC) curve analysis.

Results

LNMs were observed in 49.1% of the patients by ⁶⁸Ga-PSMA PET/CT, among which 65.5% of LNMs were pelvic-regional and 34.5% of LNMs were observed in extrareolar sites (52.1% of these were located above the diaphragm). The Briganti, MSKCC and Winter nomograms showed that 70.2%-71.9% of the patients in this study need to receive ePLND according to the EAU and NCCN guidelines. The LN staging information obtained from ⁶⁸Ga-PSMA PET/CT would have led to changes of planned management in 70.2% of these patients, including therapy modality changes in 21.1% of the patients, which were mainly due to newly detected non-regional LNMs. The thresholds of nomograms to predict non-regional LNMs were between 64% and 75%. The PC patients with a score >64% in Briganti nomogram, a score >75% in MSKCC nomogram and a score >67% in Winter nomogram were more likely to have non-regional LNMs. The AUCs (Area under curves) of the clinical nomograms (Briganti, MSKCC and Winter) in predicting non-regional LNMs were 0.816, 0.830 and 0.793, respectively.

Conclusions

By using ⁶⁸Ga-PSMA PET/CT as reference of LNM, the PLND-validated clinical nomograms can not only predict regional LNMs, but also predict non-regional LNMs. The additional information from ⁶⁸Ga-PSMA PET/CT may provide added benefit to nomograms-based clinical decision-making in more than two-thirds of patients for reducing unnecessary PLND. We focused on that a threshold can be set for current clinical PLND-validated nomograms to predict extrareolar LN metastases with an AUC accuracy of about 80% after optimizing the simple nomograms which may help to improve the efficiency for PC therapy significantly in clinical practice.

The Role of [18F]Fluciclovine PET/CT in the Characterization of High-Risk Primary Prostate Cancer: Comparison with [11C]Choline PET/CT and Histopathological Analysis

Simple Summary

The role of [¹⁸F]Fluciclovine Positron Emission Tomography/Computed Tomography (PET/CT) in the characterization of intra-prostatic lesions was evaluated in high-risk primary PCa patients, scheduled for radical surgery, comparing investigational [¹⁸F]Fluciclovine and conventional [¹¹C]Choline PET/CT results with the reference standard of pathologic surgical specimen. PET visual and semi-quantitative analyses were performed: for instance, patient-based, blinded to histopathology; subsequently lesion-based, unblinded, according to a pathology reference mapping. Among 19 pts, 45 malignant and 31 benign lesions were found. The highest SUVmax matched with the lobe of the index lesion in 89% of pts and a direct correlation between [¹⁸F]Fluciclovine uptake values and pISUP was demonstrated. Overall, the lesion-based performance of PET semiquantitative parameters (SUVmax, Target to background Ratio-TBRs) with either [¹⁸F]Fluciclovine or [¹¹C]Choline, in detecting either malignant/ISUP2-5/ISUP4-5 PCa lesions, was moderate and similar (AUCs ≥ 0.70), but still inadequate (AUCs ≤ 0.81) as standalone staging procedure. TBRs (especially with threshold higher than bone marrow) may be complementary to implement malignancy targeting.

Abstract

The primary aim of the study was to evaluate the role of [¹⁸F]Fluciclovine PET/CT in the characterization of intra-prostatic lesions in high-risk primary PCa patients eligible for radical prostatectomy, in comparison with conventional [¹¹C]Choline PET/CT and validated by prostatectomy pathologic examination. Secondary aims were to determine the performance of PET semi-quantitative parameters (SUVmax; target-to-background ratios [TBRs], using abdominal aorta, bone marrow and liver as backgrounds) for malignant lesion detection (and best cut-off values) and to search predictive factors of malignancy. A six sextants prostate template was created and used by PET readers and pathologists for data comparison and validation. PET visual and semi-quantitative analyses were performed: for instance, patient-based, blinded to histopathology; subsequently lesion-based, un-blinded, according to the pathology reference template. Among 19 patients included (mean age 63 years, 89% high and 11% very-high-risk, mean PSA 9.15 ng/mL), 45 malignant and 31 benign lesions were found and 19 healthy areas were selected (n = 95). For both tracers, the location of the “blinded” prostate SUVmax matched with the lobe of the lesion with the highest pGS in 17/19 cases (89%). There was direct correlation between [¹⁸F]Fluciclovine uptake values and pISUP. Overall, lesion-based (n = 95), the performance of PET semiquantitative parameters, with either [¹⁸F]Fluciclovine or [¹¹C]Choline, in detecting either malignant/ISUP2-5/ISUP4-5 PCa lesions, was moderate and similar (AUCs ≥ 0.70) but still inadequate (AUCs ≤ 0.81) as a standalone staging procedure. A [¹⁸F]Fluciclovine TBR-L3 ≥ 1.5 would depict a clinical significant lesion with a sensitivity and specificity of 85% and 68% respectively; whereas a SUVmax cut-off value of 4 would be able to identify a ISUP 4-5 lesion in all cases (sensitivity 100%), although with low specificity (52%). TBRs (especially with threshold significantly higher than aorta and slightly higher than bone marrow), may be complementary to implement malignancy targeting.

Prostate-specific membrane antigen PET/computed tomography for staging prostate cancer

PURPOSE OF REVIEW

Molecular imaging with PET/CT targeting the prostate-specific membrane antigen (PSMA) receptor is increasingly utilized in men with prostate cancer (PCa), with clinical indications now expanding beyond biochemical recurrence. PSMA PET/CT often detects sub-centimetre size pathologic nodes and low-volume bone marrow disease that are occult on conventional imaging when the lesion does not cause sclerosis or osteoblastic reaction in surrounding bone. This review focuses on recent evidence for PSMA PET/CT in initial disease staging.

RECENT FINDINGS

Several recent studies including a large randomized trial have evaluated the clinical impact of PSMA PET/CT in initial staging of PCa. PSMA PET/CT is more sensitive and accurate than the conventional imaging standard of CT and bone scan. Change in treatment plan or modality of therapy occurs frequently when PSMA PET/CT forms part of the diagnostic algorithm. Hybrid PET/MRI also has potential utility, particularly in evaluating pelvic disease, but evidence base remains very limited.

SUMMARY

PSMA PET/CT has emerged as a new standard in primary staging of PCa. Reimbursement by national funding bodies and incorporation into international clinical guidelines is anticipated within the next few years.

The value of 18F-PSMA-1007 PET/CT in identifying non-metastatic high-risk prostate cancer

BACKGROUND

Clinical management decisions on prostate cancer (PCa) are often based on a determination of risk. 68Ga-prostate-specific membrane antigen (PSMA)-11-positron emission tomography (PET)/computer tomography (CT) is an attractive modality to assess biochemical recurrence of PCa, detect metastatic disease and stage of primary PCa, making it a promising strategy for risk stratification. However, due to some limitation of 68Ga-PSMA-11 the development of alternative tracers is of high interest. In this study, we aimed to investigate the value of 18F-PSMA-1007 in identifying non-metastatic high-risk PCa.

METHODS

A total of 101 patients with primary non-metastatic PCa who underwent 18F-PSMA-1007 PET/CT were retrospectively analyzed. According to the European Association of Urology guidelines on PCa, patients were classified into intermediate-risk (IR) group or high-risk (HR) group. The maximum standardized uptake values (SUVmax) of the primary prostate tumor were measured on PET/CT images. The diagnostic performance of PET/CT for IR and HR PCa was calculated, and the relationship between the SUVmax of primary prostate tumor, prostate-specific antigen (PSA) level and Gleason score (GS) was analyzed.

RESULTS

Of all 101 patients, 49 patients were classified into IR group and 52 patients were classified into HR group. There was a significant positive correlation between PSA level/GS and SUVmax (r = 0.561, r = 0.496, P < 0.001, respectively). Tumors with GS 6 and 7a showed significantly lower 18F-PSMA-1007 uptake compared to patients with GS 8 and 9 (P < 0.01). SUVmax in patients of HR was significantly higher than those of IR (median SUVmax: 16.85 vs 7.80; P < 0.001). In receiver operating characteristic curve analysis, the optimal cutoff value of the SUVmax for identifying high-risk PCa was set as 9.05 (area under the curve: 0.829; sensitivity: 90.4%; specificity: 65.3%).

CONCLUSION

18F-PSMA-1007 PET/CT showed the powerful diagnosis efficacy for high-risk PCa, which can be used as an objective imaging reference index for clinical reference.

68Ga-PSMA-11 PET/CT combining ADC value of MRI in the diagnosis of naive prostate cancer: Perspective of radiologist

Ga-PSMA-11 positron emission computed tomography /computed tomography (PET/CT) is more sensitive than magnetic resonance imaging (MRI) in detecting prostate cancer (PCa). We evaluated the value of Ga-PSMA-11 PET/CT with MRI in treatment-naive PCa.This retrospective study was approved by the hospital ethics committee. The MRI and Ga-PSMA-11 PET/CT imaging data of 63 cases of highly suspected PCa were enrolled in this study. The SUVmax and apparent diffusion coefficient (ADC), and their ratio, were assessed as diagnostic markers to distinguish PCa from benign disease.There were 107 prostate lesions detected in 63 cases. Forty cases with 64 malignant primary lesions were confirmed PCa, whereas 23 cases had 43 benign lesions. PSMA-avid lesions correlated with hypointense signal on ADC maps and hyperintense signal on diffusion-weighted imaging. The ADC of PCa was lower than that of benign lesions, and SUVmax and SUVmax/ADC of PCa was higher than that of benign lesions (P < .01). ADC had significant negative correlation with Gleason score (GS) and SUVmax, SUVmax, and SUVmax/ADC positively correlated with GS. From ROC analysis, we established cutoff values of ADC, SUVmax, and SUVmax/ADC at 1.02 × 10mm/s, 11.72, and 12.35, respectively, to differentiate PCa from benign lesions. The sensitivity, specificity, and AUC were 90.6%, 58.1%, and 0.816 for ADC, 67.2%, 97.7%, and 0.905 for SUVmax, and 81.2%, 88.4%, and 0.929 for SUVmax/ADC, respectively.Ga-PSMA-11 PET/CT combined with MRI offers higher diagnostic efficacy in the detection of PCa than either modality alone.

Preclinical Evaluation of a High-Affinity Sarcophagine-Containing PSMA Ligand for 64Cu/67Cu-Based Theranostics in Prostate Cancer

The application of small molecules targeting prostate-specific membrane antigen (PSMA) has emerged as a highly promising clinical strategy for visualization and treatment of prostate cancer. Ligands that integrate the ability to both quantify the distribution of radioactivity and treat disease through the use of a matched pair of radionuclides have particular value in clinical and regulatory settings. In this study, we describe the development and preclinical evaluation of RPS-085, a ligand that binds PSMA and serum albumin and exploits the ^64/67Cu radionuclide pair for prostate cancer theranostics. RPS-085 was synthesized by conjugation of a PSMA-targeting moiety, an N^ε-(2-(4-iodophenyl)acetyl)lysine albumin binding group, and a bifunctionalized MeCOSar chelator. The IC₅₀ of the metal-free RPS-085 was determined in a competitive binding assay. The affinity for human serum albumin of the radiolabeled compound was determined by high-performance affinity chromatography. Radiolabeling was performed in NH₄OAc buffer at 25 °C. The stability of the radiolabeled compounds was assessed in vitro and in vivo. The biodistribution of [^64/67Cu]Cu-RPS-085 was determined following intravenous administration to male BALB/c mice bearing LNCaP tumor xenografts. The radiochemical yields of [^64/67Cu]Cu-RPS-085 were nearly quantitative after 20 min. The metal-free complex is a potent inhibitor of PSMA (IC₅₀ = 29 ± 2 nM), and the radiolabeled compound has moderate affinity for human serum albumin (K_d = 9.9 ± 1.7 μM). Accumulation of the tracer in mice was primarily evident in tumor and kidneys. Activity in all other tissues, including blood, was negligible, and the radiolabeled compounds demonstrated high stability in vitro and in vivo. Tumor activity reached a maximum at 4 h post injection (p.i.) and cleared gradually over a period of 96 h. By contrast, activity in the kidney cleared rapidly from 4 to 24 h p.i. As a consequence, by 24 h p.i., the tumor-to-kidney ratio exceeds 2, and the predicted dose to tumors is significantly greater than the dose to kidneys. [⁶⁴Cu]Cu-RPS-085 combines rapid tissue distribution and clearance with prolonged retention in LNCaP tumor xenografts. The pharmacokinetics should enable radioligand therapy using [⁶⁷Cu]Cu-RPS-085. By virtue of its rapid kidney clearance, the therapeutic index of [⁶⁷Cu]Cu-RPS-085 likely compares favorably to its parent structure, [¹⁷⁷Lu]Lu-RPS-063, a highly avid PSMA-targeting compound. On this basis, [^64/67Cu]Cu-RPS-085 show great promise as PSMA-targeting theranostic ligands for prostate cancer imaging and therapy.

Comparison of bone scintigraphy and Ga-68 prostate-specific membrane antigen positron emission tomography/computed tomography in the detection of bone metastases of prostate carcinoma

AIM

This study aims to assess the diagnostic performance of Ga-68 prostate-specific membrane antigen PET/computed tomography in the comparison of planar bone scintigraphy in the detection of bone metastases. Another purpose is to define the additional benefit of bone scintigraphy subsequent to prostate-specific membrane antigen PET/computed tomography and the role of prostate-specific membrane antigen PET/computed tomography in the treatment planning.

MATERIAL AND METHOD

Forty-six patients with a median interval of 19 (range: 3-90) days between prostate-specific membrane antigen PET/computed tomography and bone scintigraphy included in the analysis. Diagnostic performance of both modalities was calculated and compared.

RESULTS

Prostate-specific membrane antigen PET/computed tomography and bone scintigraphy were performed for initial staging in 25 (54%), for evaluation of biochemical recurrence in 11 (24%) and metastatic castration-resistant prostate carcinoma in 10 (22%) patients. In the patient-based analysis sensitivity, specificity, accuracy, positive predictive value, and negative predictive value for bone scintigraphy for detection of bone metastases were calculated as 50%, 19-29%, 32-39%, 32-39%, and 33-39%, respectively, based on whether equivocal findings were classified as positive or negative. For prostate-specific membrane antigen PET/computed tomography, these values were found significantly higher as 100%, 95-100%, 98-100%, 96-100%, and 100%, respectively. The diagnostic performance of bone scintigraphy and PET/computed tomography in clinical subgroups was analyzed, prostate-specific membrane antigen PET/computed tomography was superior to bone scintigraphy in three groups.

CONCLUSION

In this retrospective study, prostate-specific membrane antigen PET/computed tomography was found to be superior to planar bone scintigraphy in the detection of bone metastases. Additional bone scintigraphy seems to be unnecessary in patients who underwent prostate-specific membrane antigen PET/computed tomography within three months period without additional treatment.

Gallium-68-Labeled Prostate-Specific Membrane Antigen-11 PET/CT of Prostate and Nonprostate Cancers

OBJECTIVE. The purpose of this study is to provide a concise summary of the current experience with ⁶⁸Ga-labeled prostate-specific membrane antigen (PSMA)-11 imaging of prostate and nonprostate malignancies and benign conditions. CONCLUSION. PSMA is overexpressed in prostate cancer and in the neovasculature of many other malignancies. The relevance of PSMA as a biologic target, coupled with advances in the design, synthesis, and evaluation of PSMA-based radionuclides for imaging and therapy, is anticipated to play a major role in patient care.

Comparison of preoperative locoregional Ga-68 PSMA-11 PET-CT and mp-MRI results with postoperative histopathology of prostate cancer

BACKGROUND

Conventional imaging modalities are inadequate to evaluate locoregional extension of prostate cancer (PCa). The aim of the current retrospective study was to investigate the diagnostic efficacy of Gallium-68 prostate-specific membrane antigen-11 (Ga-68 PSMA-11) positron emission tomography/computed tomography (PET/CT) and multiparametric magnetic resonance imaging (mp-MRI) for staging preoperative PCa patients with correlating histopathology.

MATERIALS AND METHODS

Twenty-four patients with histologically proven PCa underwent both Ga-68 PSMA-11 PET/CT and mp-MRI before robot-assisted laparoscopic radical prostatectomy. For each tumor area, correlations with histopathological results were defined for tumor localization, extraprostatic extension (EPE) of the tumor, invasion of seminal vesicle (SVI) and bladder neck invasion (BNI). In patients with regional lymph node (LN) dissection, histopathological results were also correlated with imaging modalities.

RESULTS

Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for detection of EPE and SVI were higher for mp-MRI than Ga-68 PSMA-11 PET/CT. On the other hand Ga-68 PSMA-11 PET/CT had significant successful results for detection of LN metastases when compared with mp-MRI. But for BNI detection both modalities had same insufficient results. Ga-68 PSMA-11 PET/CT had strong results for appropriate tumor localization in the gland.

CONCLUSION

Ga-68 PSMA PET/CT has superior results for assessing local LN metastases and for intraprostatic tumor localization. Whereas, mp-MRI must be the preferred modality for determining SVI and EPE. But both imaging modalities failed for determining BNI accurately. Both modalities should be used in conjunction with each other for better treatment planning.