[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.

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.

A convolutional neural network-based system for fully automatic segmentation of whole-body [68Ga]Ga-PSMA PET images in prostate cancer

PURPOSE

The aim of this study was development and evaluation of a fully automated tool for the detection and segmentation of mPCa lesions in whole-body [68Ga]Ga-PSMA-11 PET scans by using a nnU-Net framework.

METHODS

In this multicenter study, a cohort of 412 patients from three different center with all indication of PCa who underwent [68Ga]Ga-PSMA-11 PET/CT were enrolled. Two hundred cases of center 1 dataset were used for training the model. A fully 3D convolutional neural network (CNN) is proposed which is based on the self-configuring nnU-Net framework. A subset of center 1 dataset and cases of center 2 and center 3 were used for testing of model. The performance of the segmentation pipeline that was developed was evaluated by comparing the fully automatic segmentation mask with the manual segmentation of the corresponding internal and external test sets in three levels including patient-level scan classification, lesion-level detection, and voxel-level segmentation. In addition, for comparison of PET-derived quantitative biomarkers between automated and manual segmentation, whole-body PSMA tumor volume (PSMA-TV) and total lesions PSMA uptake (TL-PSMA) were calculated.

RESULTS

In terms of patient-level classification, the model achieved an accuracy of 83%, sensitivity of 92%, PPV of 77%, and NPV of 91% for the internal testing set. For lesion-level detection, the model achieved an accuracy of 87-94%, sensitivity of 88-95%, PPV of 98-100%, and F1-score of 93-97% for all testing sets. For voxel-level segmentation, the automated method achieved average values of 65-70% for DSC, 72-79% for PPV, 53-58% for IoU, and 62-73% for sensitivity in all testing sets. In the evaluation of volumetric parameters, there was a strong correlation between the manual and automated measurements of PSMA-TV and TL-PSMA for all centers.

CONCLUSIONS

The deep learning networks presented here offer promising solutions for automatically segmenting malignant lesions in prostate cancer patients using [68Ga]Ga-PSMA PET. These networks achieve a high level of accuracy in whole-body segmentation, as measured by the DSC and PPV at the voxel level. The resulting segmentations can be used for extraction of PET-derived quantitative biomarkers and utilized for treatment response assessment and radiomic studies.

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.

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.

PSMA Avidity in the Heterotropic Ossification-An Incidental Finding on PSMA PET/CT

ABSTRACT

The upregulations of prostate-specific membrane antigen (PSMA) antigen are used for the presence of prostate cancer. However, published literature shows incidentally detected PSMA uptake in various nonprostatic benign and malignant conditions, which led to questioning the specificity of PSMA-targeted PET. In present case, we highlighted the abnormal PSMA expression in the benign bone abnormality.

Deep learning-based whole-body characterization of prostate cancer lesions on [68Ga]Ga-PSMA-11 PET/CT in patients with post-prostatectomy recurrence

PURPOSE

The automatic segmentation and detection of prostate cancer (PC) lesions throughout the body are extremely challenging due to the lesions' complexity and variability in appearance, shape, and location. In this study, we investigated the performance of a three-dimensional (3D) convolutional neural network (CNN) to automatically characterize metastatic lesions throughout the body in a dataset of PC patients with recurrence after radical prostatectomy.

METHODS

We retrospectively collected [68 Ga]Ga-PSMA-11 PET/CT images from 116 patients with metastatic PC at two centers: center 1 provided the data for fivefold cross validation (n = 78) and internal testing (n = 19), and center 2 provided the data for external testing (n = 19). PET and CT data were jointly input into a 3D U-Net to achieve whole-body segmentation and detection of PC lesions. The performance in both the segmentation and the detection of lesions throughout the body was evaluated using established metrics, including the Dice similarity coefficient (DSC) for segmentation and the recall, precision, and F1-score for detection. The correlation and consistency between tumor burdens (PSMA-TV and TL-PSMA) calculated from automatic segmentation and artificial ground truth were assessed by linear regression and Bland‒Altman plots.

RESULTS

On the internal test set, the DSC, precision, recall, and F1-score values were 0.631, 0.961, 0.721, and 0.824, respectively. On the external test set, the corresponding values were 0.596, 0.888, 0.792, and 0.837, respectively. Our approach outperformed previous studies in segmenting and detecting metastatic lesions throughout the body. Tumor burden indicators derived from deep learning and ground truth showed strong correlation (R2 ≥ 0.991, all P < 0.05) and consistency.

CONCLUSION

Our 3D CNN accurately characterizes whole-body tumors in relapsed PC patients; its results are highly consistent with those of manual contouring. This automatic method is expected to improve work efficiency and to aid in the assessment of tumor burden.

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 ± 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.

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.

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.

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.

Construction of truncated PSMA as a PET reporter gene for CAR T cell trafficking

In solid tumors, there are multiple barriers for a chimeric antigen receptor (CAR) T cell to surmount in order to reach the tumor site. For better understanding whether CAR T cells effectively infiltrate into tumor site, and simultaneously, whether there are off-target effects, real-time monitoring technologies need to be established. Cell-based positron emission tomography reporter genes have been developed to monitor engineered cells in living subjects. In this study, we reported the construction of a novel reporter gene truncated prostate-specific membrane antigen (ΔPSMA) pending for monitoring CAR T cells using 68Ga-PSMA-617 and a method for tracking the distribution of CAR T cells in vivo was developed. Data were provided to demonstrate that ΔPSMA was predominantly localized on the plasma membrane and could take up 68Ga-PSMA-617 in vitro in a time-dependent manner. And the expression of ΔPSMA did not affect CAR expression and cytolytic capacity of CAR T cells. CAR-ΔPSMA T cell xenografts in nude mice were clearly imaged by positron emission tomography 60 min after injection of 68Ga-PSMA-617. PSMA paired with 68Ga-PSMA-617 was capable of identifying approximately 1 × 104 engineered CAR T cells. The ability to image small numbers of CAR T cells in vivo would be helpful to accelerate the translation of cell-based therapies into the clinic, and it may reinforce our understanding of treatment success, failure, and toxicity.

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.

A prospective study of 68Ga-PSMA PET/CT imaging of HCC as diagnosed on conventional imaging to evaluate for potential 177Lu-PSMA therapy

OBJECTIVE

PSMA expression is seen in many solid tumours in addition to prostate cancer and several studies and case reports have shown PSMA expression and 68Ga-PSMA imaging of hepatocellular carcinoma (HCC). Our prospective study evaluates the role of 68Ga-PSMA in HCC patients and compares it to conventional imaging (CE-CT/MRI).

METHODS

Patients with radiologically and/or histopathologically confirmed HCC were included and all had undergone serum alpha-fetoprotein (S.AFP) assessment as well as CE-CT/MRI prior to PSMA PET/CT. Acquired whole-body PET/CTs were analysed both visually and quantitatively by two experienced nuclear medicine physicians.

RESULTS

Forty-one (41) patients (36 male; 5 female) with known HCC and a mean age of 53.9 ± 10.9 years underwent 68Ga-PSMA PET/CT. All patients had lesions on conventional imaging but only 38/41 patients showed 68Ga-PSMA uptake. Conventional imaging revealed 18 patients with single lesions, all of which were tracer avid. Twenty-three (23) of 41 patients had multifocal (> 2) hepatic lesions on CE-CT/MRI of which 3 patients showed no 68Ga-PSMA uptake, 7 showed tracer uptake in a single lesion only and 13 patients had multifocal tracer avid lesions. There was no correlation observed between S. AFP level and tumour SUVmax on 68Ga-PSMA PET/CT.

CONCLUSION

68Ga-PSMA PET/CT imaging of HCC may complement conventional imaging and identify patients for potential theranostic intervention.

68 Ga-PSMA-11 Uptake in a Large Fibroadenoma in a Male Axillary Accessory Breast

ABSTRACT

Prostate-specific membrane antigen PET imaging has revolutionized the role of prostate cancer diagnosis and management, with very high sensitivity and specificity. To prevent misdiagnosis and for accurate therapy planning, prostate-specific membrane antigen (PSMA) uptake in nonprostatic diseases needs to be recognized correctly. Besides the physiological PSMA expression, 68 Ga-PSMA-11 uptake has been mentioned in multiple oncological and nononcological lesions. The present case report exhibits 68 Ga-PSMA-11 uptake in fibroadenoma in a male accessory breast in the right axillary region.

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.

Examining the Relationship and Prognostic Significance of Cell-Free DNA Levels and the PSMA-Positive Tumor Volume in Men with Prostate Cancer: A Retrospective-Prospective [68Ga]Ga-PSMA-11 PET/CT Study

Functional imaging with prostate-specific membrane antigen (PSMA) ligands has emerged as the standard imaging method for prostate cancer (PCA). In parallel, the analysis of blood-derived, cell-free DNA (cfDNA) has been shown to be a promising quantitative biomarker of PCA aggressiveness and patient outcome. This study aimed to evaluate the relationship and prognostic value of cfDNA concentrations and the PSMA-positive tumor volume (PSMA-TV) in men with PCA undergoing [68Ga]Ga-PSMA-11 PET/CT imaging. Methods: We recruited 148 men with histologically proven PCA (mean age, 70.7 ± 7.7 y) who underwent [68Ga]Ga-PSMA-11 PET/CT (184.9 ± 18.9 MBq) and blood sampling between March 2019 and August 2021. Among these, 74 (50.0%) had hormone-sensitive PCA and 74 (50.0%) had castration-resistant PCA (CRPC). All patients provided written informed consent before blood sample collection and imaging. The cfDNA was extracted and quantified, and PSMA-expressing tumor lesions were delineated to extract the PSMA-TVs. The Spearman coefficient assessed correlations between PSMA-TV and cfDNA concentrations and cfDNA's relation with clinical parameters. The Kruskal-Wallis test examined the mean cfDNA concentration differences based on PSMA-TV quartiles for significantly correlated patient groups. Log-rank and multivariate Cox regression analyses evaluated the prognostic significance of high and low cfDNA and PSMA-TV levels for overall survival. Results: Weak positive correlations were found between cfDNA concentration and PSMA-TV in the overall group (r = 0.16, P = 0.049) and the CRPC group (r = 0.31, P = 0.007) but not in hormone-sensitive PCA patients (r = -0.024, P = 0.837). In the CRPC cohort, cfDNA concentrations significantly differed between PSMA-TV quartiles 4 and 1 (P = 0.002) and between quartiles 4 and 2 (P = 0.016). Survival outcomes were associated with PSMA-TV (P < 0.0001, P = 0.004) but not cfDNA (P = 0.174, P = 0.12), as per the log-rank and Cox regression analysis. Conclusion: These findings suggest that cfDNA might serve as a biomarker of advanced, aggressive CRPC but does not reliably reflect total tumor burden or prognosis. In comparison, [68Ga]Ga-PSMA-11 PET/CT provides a highly granular and prognostic assessment of tumor burden across the spectrum of PCA disease progression.

Potential role of 68Ga-PSMA PET/CT in metastatic renal cell cancer: A prospective study

PURPOSE

Prostate-specific membrane antigen (PSMA), in addition to its utility in prostate cancer, is also an angiogenic imaging marker for hypervascular tumors like renal cell carcinoma (RCC). Our study aims to assess the potential role of 68Ga-PSMA-11 positron emission tomography (PET)/CT in metastatic RCC and compare it with contrast-enhanced computed tomography (CECT).

METHODS

Biopsy-proven RCC patients with known or suspected distant metastases who underwent 68Ga-PSMA-11 PET/CT for staging/restaging were prospectively recruited. Those patients who had undergone 18F-FDG PET/CT within six weeks of 68Ga-PSMA PET/CT were also included retrospectively for comparative analysis. A patient-based and lesion-based analysis was done to compare the lesion detection rates of CECT, 68Ga-PSMA-11 PET and 18F-FDG PET. PET-based quantitative parameters were also compared between both the PET modalities. Impact of baseline parameters on survival was assessed using Cox regression analysis. A p-value of < 0.05 was considered significant.

RESULTS

Thirty-seven patients with median age 60 years ± 13 years (range = 26-76 years) were included in the study. Twenty-seven patients had clear cell (cc) RCC, six had papillary RCC (pRCC), and one each had an eosinophilic variant of ccRCC, collecting duct RCC, translocation RCC and poorly differentiated RCC. 68Ga-PSMA-11 PET performed better in detecting marrow and equivocal bone lesions and worse in detecting liver lesions compared to CECT. 68Ga-PSMA-11 PET-based angiogenic tumor burden estimation using Total Lesion-PSMA (TL-PSMA) and PSMA-Total volume (PSMA-TV) had a prognostic impact on the survival of patients. 68Ga-PSMA-11 PET also detected more lesions and showed significantly higher SUVmax than 18F-FDG PET.

CONCLUSION

68Ga-PSMA-11 PET/CT performs better than CECT and 18F-FDG PET/CT in metastatic evaluation and has prognostic value in the management of clear cell RCC.

Initial evaluation and external validation of 68Ga-PSMA-11 PET/CT in tubarial gland characterization

INTRODUCTION

Radiotracer 68Ga-PSMA-11 used in PET/CT scans allows for identification and localization of gland tissue. It allows for their consideration in clinical scenarios and to design further and stronger research to answer pertinent questions regarding their function and implications. We aimed to externally validate first reported findings of location, size, and ligand uptake of the tubarial glands using 68Ga-PSMA-11 PET/CT.

MATERIALS AND METHODS

A cross-sectional study was performed with 68Ga-PSMA-11 PET/CT studies of patients with prostate cancer confirmed diagnosis from the database of the Radiology Department from 2018 to 2022. The maximum cephalocaudal length (CCL) in the tubarial glands and the Maximum Standardized Uptake Value (SUVmax) of major glands were recorded.

RESULTS

A total of 202 patients were included (mean age 67.43 ± 8.5). The mean CCL of the tubarial glands was 37.38 ± 9.84 and a SUVmax of 6.56 ± 2.14. The rest of the glands were as follows: parotid 15.12 ± 4.43, submandibular 16.82 ± 5.43 and sublingual 5.84 ± 3.24. No differences were found between laterality. A weak correlation between age and SUVmax of tubarial glands was identified. Tubarial glands had a similar 68Ga-PSMA-11 uptake to that of sublingual glands.

CONCLUSION

This study corroborates the existence of a conglomerate of glands in the nasopharynx roof, near the posterolateral pharyngeal recess. It serves as validation in a different population with similar results in previous research. Without 68GA-PSMA-11 PET/CT the abundance, configuration and potential clinical relevance of these glands would probably not have been identified. Radiotracer uptake was similar amongst the major salivary glands, with a more similar uptake to that shown by the sublingual gland.

MRI and PSMA PET/CT of Biochemical Recurrence of Prostate Cancer

Prostate cancer may recur several years after definitive treatment, such as prostatectomy or radiation therapy. A rise in serum prostate-specific antigen (PSA) level is the first sign of disease recurrence, and this is termed biochemical recurrence. Patients with biochemical recurrence have worse survival outcomes. Radiologic localization of recurrent disease helps in directing patient management, which may vary from active surveillance to salvage radiation therapy, androgen-deprivation therapy, or other forms of systemic and local therapy. The likelihood of detecting the site of recurrence increases with higher serum PSA level. MRI provides optimal diagnostic performance for evaluation of the prostatectomy bed. Prostate-specific membrane antigen (PSMA) PET radiotracers currently approved by the U.S. Food and Drug Administration demonstrate physiologic urinary excretion, which can obscure recurrence at the vesicourethral junction. However, MRI and PSMA PET/CT have comparable diagnostic performance for evaluation of local recurrence after external-beam radiation therapy or brachytherapy. PSMA PET/CT outperforms MRI in identifying recurrence involving the lymph nodes and bones. Caveats for use of both PSMA PET/CT and MRI do exist and may cause false-positive or false-negative results. Hence, these techniques have complementary roles and should be interpreted in conjunction with each other, taking the patient history and results of any additional prior imaging studies into account. Novel PSMA agents at various stages of investigation are being developed, and preliminary data show promising results; these agents may revolutionize the landscape of prostate cancer recurrence imaging in the future. ©RSNA, 2023 Quiz questions for this article are available through the Online Learning Center. See the invited commentary by Turkbey in this issue. The slide presentation from the RSNA Annual Meeting is available for this article.

Impact of uptake time on image quality of [68 Ga]Ga-PSMA-11 PET/CT

BACKGROUND

With the introduction of prostate specific membrane antigen (PSMA) PET/CT, the detection rate of prostate cancer metastases has improved significantly, both for primary staging and for biochemical recurrence. EANM/SNMMI guidelines recommend a 60 min time interval between [68 Ga]Ga-PSMA administration and acquisition.

PURPOSE

This study evaluates the possibility of a shorter time interval by investigating the dynamic change in image quality measures.

METHOD

We retrospectively analyzed 10 consecutive prostate cancer patients who underwent a dynamic whole body [68 Ga]Ga-PSMA-11 PET/CT of 75 min from skull vertex to mid-thigh using Siemens FlowMotion. PET images were acquired directly after injection of 1.5 MBq/kg [68 Ga]Ga-PSMA-11. Image quality measures included lesion maximum standardized uptake value corrected for lean body mass (SULmax ), tumor-to-background ratio (TBR), and contrast-to-noise ratio (CNR). Quantitative analysis of image quality in dynamic PET was performed using PMOD (version 4.2). Regions of interest (ROIs), drawn included different types of prostate lesions (primary tumor, lymph nodes, and bone metastasis), organ tissue (liver, spleen, lacrimal gland, submandibular gland, parotid gland, urinary bladder, kidneys blood pool [ascending aorta], left ventricle), bone tissue (4th lumbar vertebral body [L4]) and muscle tissue (gluteus maximus). To further investigate image quality four 10 min multi-frame reconstructions with clinical parameters were made at different post-injection times (15, 30, 45, and 60 min). A nuclear medicine physician performed a blinded lesion detectability evaluation on these multi-frame reconstructions for different prostate cancer lesions.

RESULTS

Six primary prostate tumors in seven patients with prostate in situ, 13 lymph node metastases in six patients and up to 12 bone metastases in three patients were found. The different prostate lesion types (lymph nodes metastases, bone metastases, and primary prostate tumor) all show an increase in average SULmax , TBR, and CNR over time during the scan. The normalized average SULmax , TBR, and CNR of the combined prostate lesions at 15, 30, and 45 min post-injection scans were all significant p < 0.05 lower from the 60 min post-injection [68 Ga]Ga-PSMA-11 PET/CT (9.5 ± 4.5, 12.7 ± 6.2, and 41.8 ± 24.5, respectively). At patient level, the reader concluded the same regarding the presence/absence of primary prostate cancer recurrence, lymph node metastases, and/or bone metastases on all <60 min post-injection [68 Ga]Ga-PSMA-11 PET/CT's in comparison to the reference scan (60 min post-injection). At lesion level, all bone metastases seen on the reference scan were also seen on all <60 min post-injection [68 Ga]Ga-PSMA-11 PET/CT's but there were some lymph nodes (n = 2) metastases missed on the 15, 30, and 45 min post-injection scans. One lymph node metastasis on both the 15 and 30 min post-injection [68 Ga]Ga-PSMA-11 PET/CT's was missed and one lymph node metastasis was missed, only on the 45 min post-injection [68 Ga]Ga-PSMA-11 PET/CT.

CONCLUSION

Shorter post-injection times (15, 30, and 45 min) compared to the recommended post-injection time of 60 min are not optimal. However, the impact of a shorter time interval of 45 min instead of 60 min between [68 Ga]Ga-PSMA-11 administration and the start of PET/CT acquisition on both image quality (SULmax , TBR, and CNR) and lesion detection, while significant, is small.

Correlation between Prostate Cancer Positive Cores and 68Ga-PSMA Distribution in Prostate Gland

INTRODUCTION

The purpose of our study was to evaluate reliability of 68Ga-labeled prostate-specific membrane antigen positron emission tomography (68Ga-PSMA PET/CT) and identify appropriate SUVmax cutoff values in order to use for diagnosis, especially in patients remained clinically suspicious for prostate cancer (PCa).

METHODS

Eighty-four patients applied 68Ga-PSMA PET/CT subsequent to transrectal ultrasound-guided prostate biopsy (TRUS-bx) involved in this study retrospectively. 68Ga-PSMA PET/CT imagings were analyzed by a nuclear medicine physician, and region of interests were drawn manually in prostate diagrams including 6 segments for each patient. These marked diagrams were analyzed with histopathology reports TRUS-bx. 504 segments were grouped with Gleason scoring system, and all groups were compared with mean SUVmax values.

RESULTS

Mean SUVmax value of Gleason grade group 1 (GG1, n: 352 segments) was 6.6 (±4.6) and significantly lower than the other groups (p < 0.001). No significant difference was detected within GG2-5 groups (p > 0.05). According to receiver operating characteristic curve analysis, SUVmax cutoff values were 1.0 (AUC: 0.961) for tumor detection, yielding a sensitivity, specificity, positive predictive value, negative predictive value of 99.4%, 92.1%, 96.5%, 98%, respectively, and 4.2 (AUC: 0.853) for detection of clinically significant PCa with 88.8%, 62.4%, 84.5%, and 71%, respectively. Although tumor percentage of biopsy core and Gleason group were correlated with SUVmax uptake, but patient age was not.

CONCLUSION

68Ga-PSMA PET appears to be a reliable option for diagnosis and disease management in PCa and can be considered especially in discrimination of csPCa, and patients remained suspicious for disease.

Total-body [68 Ga]Ga-PSMA-11 PET/CT improves detection rate compared with conventional [68 Ga]Ga-PSMA-11 PET/CT in patients with biochemical recurrent prostate cancer

PURPOSE

The purpose of this study was to assess whether total-body [68 Ga]Ga-PSMA-11 PET/CT could improve the detection rate compared with conventional [68 Ga]Ga-PSMA-11 PET/CT in patients with biochemical recurrent prostate cancer.

METHODS

Two hundred biochemical recurrent prostate cancer patients with similar clinicopathological characteristics were included, of whom 100 patients underwent early total-body [68 Ga]Ga-PSMA-11 PET/CT and diuretic-delayed total-body [68 Ga]Ga-PSMA-11 PET/CT, and the other 100 patients received early conventional [68 Ga]Ga-PSMA-11 PET/CT and diuretic-delayed conventional [68 Ga]Ga-PSMA-11 PET/CT. The detection rates of total-body [68 Ga]Ga-PSMA-11 PET/CT and conventional [68 Ga]Ga-PSMA-11 PET/CT were compared using a chi-square test and stratified analysis. The image quality of total-body [68 Ga]Ga-PSMA PET/CT and conventional [68 Ga]Ga-PSMA-11 PET/CT was compared based on subjective scoring and objective parameters. Subjective scoring was conducted from background noise and lesion prominence using a 5-point scale. Objective parameters were evaluated by SUVmax, SUVmean, the standard deviation (SD) of SUV, and the signal-to-noise ratio (SNR) of liver and gluteus maximus. The SUVmax of the recurrent lesions was also measured.

RESULTS

The liver SD of the total-body [68 Ga]Ga-PSMA-11 PET/CT was significantly lower than that of conventional [68 Ga]Ga-PSMA-11 PET/CT, the SNR was significantly higher than that of conventional [68 Ga]Ga-PSMA-11 PET/CT, and the subjective evaluation was significantly better than that of conventional [68 Ga]Ga-PSMA-11 PET/CT. The detection rate of total-body [68 Ga]Ga-PSMA PET/CT for biochemical recurrence of prostate cancer was significantly higher than that of conventional [68 Ga]Ga-PSMA-11 PET/CT (91.0% vs. 74.0%, P = 0.003). Total-body [68 Ga]Ga-PSMA-11 PET/CT had better detection efficiency for patients with a Gleason score ≤ 8 or PSA ≤ 2 ng/ml. The advantages of diuretic-delayed total-body [68 Ga]Ga-PSMA-11 PET/CT were more obvious.

CONCLUSION

Total-body [68 Ga]Ga-PSMA-11 PET/CT could significantly improve the detection rate compared with conventional [68 Ga]Ga-PSMA-11 PET/CT in patients with biochemical recurrent prostate cancer.

Can the Gleason score be predicted in patients with prostate cancer? A dynamic contrast-enhanced MRI, (68)Ga-PSMA PET/CT, PSA, and PSA-density comparison study

PURPOSE

The present study aims to evaluate whether perfusion parameters in prostate magnetic resonance imaging (MRI), (68)Ga-prostate-specific membrane antigen (PSMA) positron emission tomography (PET)/computed tomography (CT), prostate-specific antigen (PSA), and PSA density can be used to predict the lesion grade in patients with prostate cancer (PCa).

METHODS

The study included a total of 137 PCa cases in which 12-quadrant transrectal ultrasound-guided prostate biopsy (TRUSBx) was performed, the Gleason score (GS) was determined, and pre-biopsy multiparametric prostate MRI and (68)Ga-PSMA PET/CT examinations were undertaken. The patient population was evaluated in three groups according to the GS: (1) low risk; (2) intermediate risk; (3) high risk. The PSA, PSA density, pre-TRUSBx (68)Ga-PSMA PET/CT maximum standardized uptake value (SUVmax), perfusion MRI parameters [maximum enhancement, maximum relative enhancement, T0 (s), time to peak (s), wash-in rate (s-1), and wash-out rate (s-1)] were retrospectively evaluated.

RESULTS

There was no significant difference between the three groups in relation to the PSA, PSA density, and (68)Ga-PSMA PET/CT SUVmax (P > 0.05). However, the values of maximum enhancement, maximum relative enhancement (%), T0 (s), time to peak (s), wash-in rate (s-1), and wash-out rate (s-1) significantly differed among the groups. A moderate positive correlation was found among the prostate volume, PSA (r = 0.490), and (68)Ga-PSMA SUVmax (r = 0.322) in the patients. The wash-out rate (s-1) and wash-in rate (s-1) had the best diagnostic test performance (area under the curve: 89.1% and 78.4%, respectively).

CONCLUSION

No significant correlation was found between the (68)Ga-PSMA PET/CT SUVmax and the GS. The wash-out rate was more successful in estimating the pretreatment GS than the (68)Ga-PSMA PET/CT SUVmax.

How reliable is the high-volume definition in prostate cancer patients: the potential game-changing role of PSMA

PURPOSE

To evaluate whether metabolic and volumetric data from 68 Ga-PSMA PET/CT performed during staging of de-novo high-volume mCSPC patients who received docetaxel could be used to predict survival.

METHODS

Forty-two de-novo high-volume mCSPC patients, who received ADT + Docetaxel and underwent 68 Ga-PSMA PET/CT for staging, were included in the study. The association between patients' pathological data, all PSA measurements, treatments they received, the data obtained from 68 Ga-PSMA PET/CT and progression-free and overall survival were examined.

RESULTS

In the multivariate analysis, PSMA-TV (primary) and PSMA-TV (WB) variables were shown to be independent negative predictors of overall survival. For the threshold value of 19.91 cm 3 obtained for PSMA-TV (primary), HR was calculated as 6.31, the 95% confidence interval (CI): 1.01-39.18, P = 0.048. For the threshold value of 1226.5 cm 3 obtained for PSMA-TV (WB) variable, HR was calculated as 58.62, the 95% CI: 2.55-1344.43, P = 0.011. In our study, SUVmax (WB) variable was found to be an independent and negative predictor of progression-free survival. For the determined threshold value of 17.74, HR was calculated as 16.24, 95% CI: 1.18-22.76, P = 0.037.

CONCLUSION

Metabolic and volumetric data obtained from 68 Ga-PSMA PET/CT can be used to predict survival in de-novo high-volume mCSPC. Our results show that in ADT + Docetaxel receiving patients, a subgroup with higher PSMA-TV (WB) values have a significantly worse prognosis. This situation suggests that the high-volume disease definition in the literature may be insufficient for this group, and that 68 Ga-PSMA PET/CT can play an essential role in demonstrating the heterogeneity within the group.

Aberrant Vascular Anatomy Associated With Artifactual Focal Avidity in the Liver on PSMA PET

ABSTRACT

68 Ga-prostate-specific membrane antigen (PSMA) PET/CT is a valuable tool for staging and restaging of prostate cancer. Prostate-specific membrane antigen expression is not specific to prostate cancer, as it is expressed in normal tissues as well as in neoplastic and nonneoplastic processes. Awareness of the broad possibility of lesions with PSMA avidity is necessary to recognize normal variants and avoid potential pitfalls in image interpretation. We present a series of cases showing physiologic focal PSMA avidity in hepatic segment IVb. We correlate this uptake with aberrant hepatic vasculature. The awareness of this variant is important for accurate image interpretation to prevent additional invasive procedures, undue treatment escalation, and denial of curative treatment to patients.

Development of PSMA-PET-guided CT-based radiomic signature to predict biochemical recurrence after salvage radiotherapy

PURPOSE

To develop a CT-based radiomic signature to predict biochemical recurrence (BCR) in prostate cancer patients after sRT guided by positron-emission tomography targeting prostate-specific membrane antigen (PSMA-PET).

MATERIAL AND METHODS

Consecutive patients, who underwent 68Ga-PSMA11-PET/CT-guided sRT from three high-volume centers in Germany, were included in this retrospective multicenter study. Patients had PET-positive local recurrences and were treated with intensity-modulated sRT. Radiomic features were extracted from volumes of interests on CT guided by focal PSMA-PET uptakes. After preprocessing, clinical, radiomics, and combined clinical-radiomic models were developed combining different feature reduction techniques and Cox proportional hazard models within a nested cross validation approach.

RESULTS

Among 99 patients, median interval until BCR was the radiomic models outperformed clinical models and combined clinical-radiomic models for prediction of BCR with a C-index of 0.71 compared to 0.53 and 0.63 in the test sets, respectively. In contrast to the other models, the radiomic model achieved significantly improved patient stratification in Kaplan-Meier analysis. The radiomic and clinical-radiomic model achieved a significantly better time-dependent net reclassification improvement index (0.392 and 0.762, respectively) compared to the clinical model. Decision curve analysis demonstrated a clinical net benefit for both models. Mean intensity was the most predictive radiomic feature.

CONCLUSION

This is the first study to develop a PSMA-PET-guided CT-based radiomic model to predict BCR after sRT. The radiomic models outperformed clinical models and might contribute to guide personalized treatment decisions.

Bony lesion analysis in carcinoma prostate: methylene diphosphonate bone scan vs. Gallium-68 psma-11 pet/ct

BACKGROUND

Prostate cancer is the cause of the highest cancer-related death in males, 5-year survival is 31% in metastatic disease, and bone is a common site of metastases. Bone scintigraphy is a routinely used imaging modality for detecting skeletal metastases. It has variable sensitivity of 52-100%, whereas PSMA PET/CT scans have better sensitivity approaching 100%, so we determined the diagnostic accuracy, sensitivity, and specificity of planar M.D.P. (Methylene diphosphonate) bone scintigraphy.

METHODS

This analytical cross-sectional study was conducted at the N.M. & molecular imaging department of S.I.U.T. Karachi. Bone scans and PSMA-PET/CT scans of all patients who were visited from Janury-2018 to January 2023 were reviewed and interpreted by a nuclear physician& radiologist team. Inclusion criteria were histopathology-proven prostate cancer patients who had a bone scan and PSMA PET/CT scan within one month and had not received any treatment between scans.

RESULTS

Among 70 scans, 38 (54.2%) were positive for bone lesions. A total of 18 (47%) patients had positive bony lesions on both PSMA-PET/CT and Bone scintigraphy. Among 38 bone lesions positive patients, in eleven patients, bone lesions were detected only on PET/CT scans, whereas nine were positive only on Bone scans. The mean S.U.V. max of all bony lesions was 19.15 (range 3.2-57.5). The bone scan's sensitivity, specificity, and accuracy were 62.07%, 78.05%, and 62.87%, respectively.

CONCLUSIONS

PSMA-PET/CT is better than bone Scintigraphy for detecting skeletal metastases. However, outcomes of bone scintigraphy may be improved when Tc-PSMA receptor bone scintigraphy is used.

Incidental Meningioma With Altered PSMA Expression After Systemic Hormone Therapy and Local Radiotherapy Detected by 68 Ga-PSMA PET/CT

ABSTRACT

A 59-year-old man underwent radical prostatectomy for adenocarcinoma in 2009. Because of the progression of PSA levels, a 68 Ga-PSMA PET/CT scan was performed in January 2020. A suspicious uptake was detected in the left cerebellar hemisphere, and there was no evidence of distant metastatic disease other than recurrent malignancy in the prostatectomy bed. MRI revealed a meningioma located in the left cerebellopontine angle. Although PSMA uptake of the lesion increased in the first imaging after hormone therapy, partial regression was noted after radiotherapy applied to this region.

Early biochemical outcomes following PSMA guided approach for bIoCHEmical relapse after prostatectomy-PSICHE trial (NCT05022914): preliminary results

PSICHE (NCT05022914) is a prospective trial to test a [68Ga]Ga- PSMA-11 PET/CT imaging tailored strategy. All evaluable patients had biochemical relapse after surgery and underwent centralized [68Ga]Ga-PSMA-11 PET/CT imaging. The treatment was performed according pre-defined criteria. Observation and re-staging at further PSA progression were proposed to patients with negative PSMA and previous postoperative RT. Prostate bed SRT was proposed to all patients with a negative staging or positive imaging within prostate bed. Stereotactic body radiotherapy (SBRT) to all sites of disease was used for all patients with pelvic nodal recurrence (nodal disease < 2 cm under aortic bifurcation) or oligometastatic disease. At 3 months after treatment, 54.7% of patients had a complete biochemical response Only 2 patients experienced G2 Genitourinary toxicity. No G2 Gastrointestinal toxicity was recorded. A PSMA targeted treatment strategy led to encouraging results and was well tolerated.

Head-to-Head Comparison of 68 Ga-P16-093 and 68 Ga-PSMA-617 PET/CT in Patients With Primary Prostate Cancer : A Pilot Study

PURPOSE

We aimed to compare the diagnostic performance of 68 Ga-P16-093 and 68 Ga-PSMA-617 PET/CT in primary prostate cancer (PCa) patients.

PATIENTS AND METHODS

Thirty untreated primary PCa patients were enrolled. Each patient underwent 68 Ga-P16-093 and 68 Ga-PSMA-617 PET/CT within a week. In addition to visual analysis, SUV was measured for semiquantitative comparison and correlation analysis.

RESULTS

68 Ga-P16-093 PET/CT detected more positive tumors than 68 Ga-PSMA-617 PET/CT (67 vs 56, P = 0.002), especially for intraprostatic lesions (29 vs 24, P = 0.025) and lymph node metastases (23 vs 17, P = 0.034). Further, 68 Ga-P16-093 PET/CT exhibited significantly higher SUV max of matched tumors (18.3 ± 14.4 vs 13.9 ± 11.8, P < 0.001). Besides, the SUV max of high-risk patients (based on D'Amico classification) on 68 Ga-P16-093 PET/CT was significantly higher than that of low- and intermediate-risk PCa patients (20.9 ± 9.9 vs 8.9 ± 9.1 vs 10.1 ± 5.2, P = 0.007). The SUV max of tumor measured by 68 Ga-P16-093 PET/CT had a moderate association with biopsy Gleason score ( r = 0.462, P = 0.005) and prostate-specific antigen value ( r = 0.491, P = 0.002), and significantly correlated with PSMA expression ( r = 0.732, P < 0.001).

CONCLUSIONS

68 Ga-P16-093 PET/CT exhibited higher tumor uptake and potentially better tumor detection capability than 68 Ga-PSMA-617 PET/CT, which suggested that 68 Ga-P16-093 may be more suitable in the diagnosis and staging of primary PCa patients.

Intense Diffuse Lung Uptake Due to Interstitial Pneumopathy Related to Polyangiitis Granulomata in 68 Ga-PSMA-11 PET/CT

ABSTRACT

We reported the case of a 73-year-old man for whom a prostatic adenocarcinoma with synchronous bone metastases was diagnosed. Because his disease was progressing despite several lines of chemotherapy and hormonotherapy, he was screened with a 68 Ga-PSMA PET/CT for a possible 177 Lu-PSMA-617 therapy. The examination demonstrated an intense diffuse bone uptake related to the known bone involvement. It also showed an unexpected diffuse and intense lung uptake, secondary to an active polyangiitis granulomata. This intense lung uptake prohibits the radioligand therapy.

Comparison of the preparation of the radiopharmaceutical 68Ga-PSMA-11 at two Czech worksites

Radiopharmaceutical 68Ga-PSMA-11 is one of the newest positron radiopharmaceuticals available for nuclear medicine departments in the Czech Republic. The radiopharmaceutical preparation can be carried out manually or instrumentally using modules for synthesis. Despite the greater technological difficulty of preparation, the success of synthesis of this radiopharmaceutical by both methods is very high, and the evaluated quality parameters of the radiopharmaceutical are comparable by both manual and instrumental preparation methods. Also, regarding professional exposure, the preparation of 68Ga-PSMA-11 does not significantly affect the whole-body and finger dosimetry results.

Failure Patterns by PSMA PET for Recurrent Prostate Cancer after Prostatectomy and Salvage Radiation

OBJECTIVE

To characterize patterns of failure using prostate-specific membrane antigen positron emission tomography (PSMA PET) after radical prostatectomy (RP) and salvage radiotherapy (SRT).

METHODS

Patients with rising PSA post-RP+SRT underwent 68Ga-HBED-iPSMA PET/CT on a single-arm, prospective imaging trial (NCT03204123). Scans were centrally reviewed with pattern-of-failure analysis by involved site. Positive scans were classified using 3 failure categories: pelvic nodal, extra-pelvic nodal or distant non-nodal. Associations with failure categories were analyzed using cumulative incidence and generalized logits regression.

RESULTS

We included 133 men who received SRT a median of 20 months post-RP; 56% received SRT to the prostatic fossa alone, while 44% received pelvic SRT. PSMA PET/CT was performed a median of 48 months post-SRT. Overall, 31% of PSMA PET/CT scans were negative, 2% equivocal and 67% had at least 1 positive site. Scan detection was significantly associated with PSA level prior to PSMA PET/CT. Analysis of 89 positive scans demonstrated pelvic nodal (53%) was the most common relapse and fossa relapse was low (9%). Overall, positive scans were pelvic (n = 35, 26%), extra-pelvic nodal (n = 26, 20%) or distant non-nodal failure (n = 28, 21%), and 70% of positive scans were oligorecurrent. We observed similar cumulative incidence for all failure categories and relatively few clinicodemographic associations. Men treated with pelvic SRT had reduced odds of pelvic failure versus exclusive fossa treatment.

CONCLUSION

Pelvic, extra-pelvic nodal, and distant non-nodal failures occur with similar incidence post-SRT. Regional nodal relapse is relatively common, especially with fossa-only SRT. A high oligorecurrence rate suggests a potentially important role for PSMA-guided focal therapies.

Comparison of 68Ga-PSMA PET/CT and mp-MRI in regard to local staging for prostate cancer with histopathological results: A retrospective study

BACKGROUND

Imaging modalities are used to diagnose and clinical grading of clinically significant prostate cancer. In this study, 68Ga-PSMA PET/CT (PSMA) and multiparametric prostate MRI (mp-MRI) were compared in regard to locating intraprostatic tumor and locoregional staging.

METHODS

After ethics committee approval, a total of 49 patients with prostate cancer who had mp-MRI and PSMA before radical prostatectomy were included. Preoperative and postoperative PSA, transrectal ultrasound-guided prostate biopsy (TRUS-Bx) ISUP grade, radical prostatectomy ISUP grade, body mass index (BMI), TRUS prostate volume, mp-MRI tumor mapping, PSMAtumor mapping, pathologic tumor mapping, extraprostatic extension (EPE), seminal vesicle invasion (SVI), lymph node invasion (LNI), and bladder neck invasion (BNI)were retrospectively evaluated. Index tumor was located by uroradiologist, nuclear medicine specialist, and uropathologist on a 12-sector prostate pathology map and compared with each other in terms of accuracy and locoregional clinical staging.

RESULTS

Mean age of the patients was 66.18 ± 6.67 years and the mean of preoperative PSA results was 21.11 ± 32.56 ng/ml. Nearly half of the patients' (44.9%) pathology was reported as ISUP grade 4 and 5% and 18.4% of patients were surgical margin positive. According to the pathological findings, 362 out of 588 sectors were tumor-positive, 174 out of 362 sectors were tumor-positive in mp-MRI, and 175 out of 362 sectors were tumor-positive in PSMA. Both PSMA and mp-MRI were comparable (p = 0.823) and accurate to detect the location of the intraprostatic index tumor (AUC = 0.66 vs. 0.69 respectively, p = 0.82). The sensitivity and the specificity of the PSMA and mp-MRI for localizing intraprostatic index tumors were 42.5% versus 49.5% and 90.7% versus 88.6% respectively. mp-MRI was more accurate than PSMA in terms of EPE (AUC = 0.8 vs. AUC = 0.57 respectively, p = 0.027) and both methods were comparable in terms of SVI (AUC = 0.75 vs. AUC = 0.75, p = 0.886) and BNI (AUC = 0.51 vs. AUC = 0.59, p = 0.597). PSMA and mp-MRI were comparable in terms of LNI (AUC = 0.76 vs. AUC = 0.64, p = 0.39).

CONCLUSION

mp-MRI should be considered for its high accuracy in the diagnosis of EPE, especially before decision-making for nerve-sparing surgery in high-risk patients. Both imaging modalities were accurate for localizing intraprostatic index tumor. PSMA is accurate for detecting LNI.

Optimization of prostate cancer patient lymph node staging via the integration of neutrophil-lymphocyte ratios, platelet-lymphocyte ratios, and 68 Ga-PSMA-PET-derived SUVmax values

BACKGROUND

At present, standardized parameters for quantitatively evaluating ⁶⁸ Ga-PSMA-PET/CT outcomes when diagnosing lymph node metastasis in prostate cancer patients are lacking. Inflammatory hematological biomarkers offer value as robust predictors of certain cancer-related outcomes. The present study was thus developed to explore approaches to improving the utility of ⁶⁸ Ga-PSMA-PET/CT for diagnosing lymph node metastasis through the combined evaluation of inflammatory hematological markers in prostate cancer patients.

METHODS

Pretreatment patient details including age, initial TPSA levels, hematological findings, biopsy pathology results (Gleason score and ISUP grouping), radical pathology results, and imaging details were collected. Optimal cutoff values for each predictor then being determined based upon Youden's index, with univariate and multivariate analyses were then used to identify independent predictors of lymph node metastasis and used to construct a nomogram.

RESULT

Independent predictors of lymph node metastasis in this patient cohort included SUVmax (odds ratio [OR]: 30.549, 95% confidence interval [CI]: 10.855-85.973, p < 0.001), neutrophil-lymphocyte ratio (OR:8.221, 95%CI: 1.335-50.614, p = 0.023), platelet-lymphocyte ratio (OR:8.221, 95% CI: 1.335-50.614, p = 0.023), initial TPSA (OR:2.761, 95% CI: 1.132-6.733, p = 0.026), and clinical T-stage (T3 vs. T2, OR:11.332, 95% CI:3.929-32.681, p < 0.001; T4 vs. T2, OR:9.101, 95% CI:1.962-42.213, p = 0.005), with corresponding optimal cutoff values of 2.3 (area under the curve [AUC]: 0.873, sensitivity: 0.736, specificity: 0.902), 1.72 (AUC: 0.558, sensitivity: 0.529, specificity: 0.643), 83.305 (AUC: 0.651, sensitivity: 0.299, specificity: 0.979), and 21.875 (AUC: 0.672, sensitivity: 0.736, specificity: 0.601). Subsequent nomogram construction was associated with good predictive ability, with a C-index of 0.887(95% CI: 0.793-0.981) and an AUC of 0.924 (95% CI: 0.882-0.965).

CONCLUSION

SUVmax, the neutrophil-lymphocyte ratio, the platelet-lymphocyte ratio, initial TPSA, and clinical T-stage represent valuable independent predictors of lymph node metastasis in prostate cancer patients, offering an opportunity to further optimize lymph node staging for these patients.

Intense 68 Ga-PSMA Uptake in Neurofibroma Mimicking Cutaneous Metastases in a Patient With Prostate Cancer

ABSTRACT

Prostate cancer is the most common cancer in men. 68 Ga-PSMA PET/CT is frequently used in staging and restaging prostate cancer; it is important to keep in mind the causes of false-positives when evaluating imaging. We present findings of 68 Ga-PSMA PET/CT and histopathological features of a 68-year-old prostate cancer man with neurofibroma. 68 Ga-PSMA PET/CT showed intense 68 Ga-PSMA uptake in neurofibroma.

Vas Deferens and Inguinal Canal Metastasis of Prostate Cancer Revealed by 68 Ga-Prostate-Specific Membrane Antigen PET/CT

ABSTRACT

A 71-year-old man with prostate adenocarcinoma underwent 68 Ga-prostate-specific membrane antigen (PSMA) PET/CT for staging. 68 Ga-PSMA PET/CT showed the primary lesion along with bladder, rectum, bilateral seminal vesicle invasion, and metastatic pelvic lymph nodes with intense 68 Ga-PSMA uptake. Also, PET/CT showed rarely seen bilateral vas deferens invasion and metastasis to the inguinal canal. These rare metastases may be indicative of poor biological behavior and prognosis.

68Ga-PSMA Uptake in Brain Metastasis of Gastric Carcinoma

ABSTRACT

A 69-year-old man with a known history of gastric and prostate adenocarcinoma was referred to 68Ga-prostate-specific membrane antigen (PSMA) PET/CT for restaging due to biochemical recurrence of prostate cancer. 68Ga-PSMA PET/CT revealed tracer accumulation in the primary prostatic lesion, lymph node, bone metastases, and brain lesion, which was later confirmed on biopsy to be metastasis of gastric carcinoma. This case reminds us of the variable spectrum of 68Ga-PSMA uptake in prostatic and nonprostatic metastatic lesions, the potential pitfalls on PET/CT images in the workup of patients with concomitant malignancies.

Molecular Imaging of Neuroendocrine Prostate Cancer by Targeting Delta-Like Ligand 3

Treatment-induced neuroendocrine prostate cancer (NEPC) is a lethal subtype of castration-resistant prostate cancer. Using the 89Zr-labeled delta-like ligand 3 (DLL3) targeting antibody SC16 (89Zr-desferrioxamine [DFO]-SC16), we have developed a PET agent to noninvasively identify the presence of DLL3-positive NEPC lesions. Methods: Quantitative polymerase chain reaction and immunohistochemistry were used to compare relative levels of androgen receptor (AR)-regulated markers and the NEPC marker DLL3 in a panel of prostate cancer cell lines. PET imaging with 89Zr-DFO-SC16, 68Ga-PSMA-11, and 68Ga-DOTATATE was performed on H660 NEPC-xenografted male nude mice. 89Zr-DFO-SC16 uptake was corroborated by biodistribution studies. Results: In vitro studies demonstrated that H660 NEPC cells are positive for DLL3 and negative for AR, prostate-specific antigen, and prostate-specific membrane antigen (PSMA) at both the transcriptional and the translational levels. PET imaging and biodistribution studies confirmed that 89Zr-DFO-SC16 uptake is restricted to H660 xenografts, with background uptake in non-NEPC lesions (both AR-dependent and AR-independent). Conversely, H660 xenografts cannot be detected with imaging agents targeting PSMA (68Ga-PSMA-11) or somatostatin receptor subtype 2 (68Ga-DOTATATE). Conclusion: These studies demonstrated that H660 NEPC cells selectively express DLL3 on their cell surface and can be noninvasively identified with 89Zr-DFO-SC16.

Potential Pitfall in the Interpretation of Ganglioneuronal Uptake of 18 F-PSMA-1007 PET/CT Scans Performed With a High Spatial Resolution Digital PET Scanner

ABSTRACT

A 69-year-old man with biochemical recurrence of prostate cancer after radical prostatectomy 5 years previously and subsequent salvage radiotherapy to the prostate bed and pelvic nodes underwent PET/CT on a Siemens mCT Flow PET and a second PET/CT 10 months later on a Siemens Vision 600 Digital PET. In addition to a suspicious left hilar lymph node, the new high-resolution PET showed increased visualization and avidity of physiologic uptake in paraspinal and presacral sympathetic ganglia. Caution should be undertaken when interpreting PET/CTs performed on high-resolution digital scanners to avoid mistaking ganglia uptake for metastatic disease.

The Relationship between the SUVmax Value Obtained in Ga-68 PSMA PET/CT and Lactate Dehydrogenase and Alkaline Phosphatase in Prostate Cancer

OBJECTIVES

ALP and LDH are serum markers of prognostic importance in prostate cancer patients. PET/CT imaging with Ga-68 PSMA has played an important role in prostate cancer imaging in recent years. Our aim in this study was to evaluate the relationship and prognostic significance between SUVmax values obtained with Ga-68 PSMA PET/CT and LDH and ALP levels in prostate cancer patients.

METHODS

We retrospectively evaluated 61 prostate cancer patients who had Ga-68 PSMA PET/CT imaging and who did not have a prostatectomy between 2019 and 2020. PSA, ALP and LDH levels were measured in all patients before or after imaging within a maximum of 28 days.

RESULTS

The median age of the patients included in this study was 73 (range: 57-89) and all 61 patients were prostatic adenocarcinoma. 50 (82%) of the patients had distant metastasis in Ga-68 PSMA PET/CT. There was a significant positive correlation between serum LDH and PSA levels. There was a positive correlation between serum ALP and PSA levels. A negative correlation was found between ALP levels and prostate SUVmax.

CONCLUSIONS

While negative correlation was found between SUVmax and ALP levels, no correlation was found between LDH levels and SUVmax. High ALP levels were found to be related to metastasis rates and severity and high serum PSA levels.