Current state of prostate-specific membrane antigen PET/CT imaging-targeted biopsy techniques for detection of clinically significant prostate cancer

Key learnings from concordant systematic biopsies in prostate-specific membrane antigen positron emission tomography/computed tomography-guided prostate biopsies: Enhancing targeting accuracy

BACKGROUND

Prostate cancer (PCa) diagnosis and staging have evolved with the advent of 68Ga-Prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA-PET/CT). This study investigates the role of complementary systematic biopsies (SB) during PSMA-PET/CT-guided targeted prostate biopsies (PET-TB) for PCa detection, grading, and distribution. We address the uncertainty surrounding the necessity of SB in conjunction with PET-TB.

METHODS

We analyzed PCa grading and distribution in 30 men who underwent PET-TB and SB because of contraindication to magnetic resonance imaging or high clinical suspicion of PCa. Tumor distribution was assessed in relation to the PET-highlighted lesions. Standardized reporting schemes, encompassing SUVmax , PRIMARY score, and miTNM classification, were evaluated.

RESULTS

80% of patients were diagnosed with PCa, with 70% classified as clinically significant (csPCa). SB detected more csPCa cases than PET-TB, but the differences were not statistically significant. Discordant results were observed in 25% of cases, where SB outperformed PET-TB. Spatial analysis revealed that tumor-bearing cores from SB were often located in close proximity to the PET-highlighted region. Reporting schemes showed potential for csPCa detection with significantly increased SUVmax in csPCA patients. Subsequent follow-up data underscored the importance of SB in precise PCa grading and staging.

CONCLUSIONS

While PET-TB can simplify prostate biopsy and reduce invasiveness by core number, SB cannot be omitted yet due to potential PET-TB targeting errors. Factors such as limited spatial resolution and fusion inaccuracies contribute to the need for SB. Standardization in reporting schemes currently cannot compensate for targeting errors highlighting the need for refinement.

Advances in radiology and pathology of prostate cancer: a review for the pathologist

Multiparametric magnetic resonance imaging (mpMRI) has improved systematic prostate biopsy procedures in the diagnosis of clinically significant prostate cancer (csPCa) by reducing the number of unnecessary biopsies; numerous level one evidence studies have confirmed the accuracy of MRI-targeted biopsy, but, still today, systematic prostate biopsy is recommended to reduce the 15-20% false negative rate of mpMRI. New advanced imaging has been proposed to detect suspicious lesions and perform targeted biopsies especially when mpMRI cannot be performed. Transrectal ultrasound (TRUS) modalities are emerging as methods with greater sensitivity and specificity for the detection of PCa compared to the traditional TRUS; these techniques include elastography and contrast-enhanced ultrasound, as well as improved B-mode and Doppler techniques. These modalities can be combined to define a novel ultrasound approach: multiparametric ultrasound (mpUS). More recently, micro-ultrasound (MicroUS) and prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) have demonstrated to be sensitive for the detection of primary prostatic lesions resulting highly correlated with the aggressiveness of the primary prostatic tumor. In parallel, artificial intelligence is advancing and is set out to deeply change both radiology and pathology. In this study we address the role, advantages and shortcomings of novel imaging techniques for Pca, and discuss future directions including the applications of artificial intelligence-based techniques to imaging as well as histology. The significance of these findings for the practicing pathologist is discussed.

Future Imaging of Prostate Cancer: Do We Need More Than PSMA PET/CT?

In the setting of prostate cancer (PCa), many different imaging modalities are available to correctly assess staging, restaging, treatment response and radio-ligand therapy recruitment. The introduction of fluoride or gallium-labelled prostate specific membrane antigen (PSMA) made a revolution in PCa management, also due to its possible theragnostic use. Nowadays PSMA-PET/CT is a fundamental tool for staging and restaging PCa. This review discusses the latest findings in PSMA imaging in PCa patients and the impact of PSMA imaging on the patients' management in primary staging, biochemical recurrence and in advanced prostate cancer, always keeping in mind the important theragnostic role of PSMA. This review tries also to assess the current role of other radiopharmaceuticals as Choline, FACBC or other radiotracers like gastrin-releasing peptide receptor targeting tracers and FAPI in different PCa settings.

Targeted Biopsy in Men High Risk for Prostate Cancer: 68Ga-PSMA PET/CT Versus mpMRI

INTRODUCTION/BACKGROUND

To evaluate the accuracy of 68Ga-PSMA PET/CT versus mpMRI targeted biopsy (TPBx) in the diagnosis of clinically significant prostate cancer (csPCa) in men high risk for PCa.

MATERIALS AND METHODS

From January 2021 to March 2023, 125 men with clinical parameters high risk for PCa were evaluated by mpMRI and 68Ga-PSMA PET/CT; median PSA was 32.5 ng/mL (range: 12-160 ng/mL) and 60/125 (48%) had abnormal digital rectal examination. The mpMRI lesions with PI-RADS scores ≥ 3 and/or 68Ga-PSMA areas characterized by a standardized uptake value (SUVmax) values ≥ 8 were submitted to TPBx (4 cores); in addition, all the patients underwent systematic transperineal prostate biopsy (18 cores) under sedation and antibiotic prophylaxis.

RESULTS

In 80 of 125 men (64%) a csPCa was found: 10 (12.5%) had a ISUP Grade Group 3 (GG), 45 (56.2%) a ISUP GG4 and 25 (31.2%) ISUP GG5. The median intraprostatic 68Ga-PSMA SUVmax was 42.3 (range:10.5-164) and 72 of 80 (90%) had a PI-RADS score ≥ 3. 68GaPSMA PET/CT showed the presence of metastases in 20 of 80 (25%) men: the median SUVmax in bone (15 cases) and nodes (40 cases) metastases was 55 and 47, respectively. Accuracy of 68Ga PSMA PET/CT (SUVmax cut-off ≥ 8) versus mpMRI PI-RADS score ≥ 3 in the diagnosis of csPCa was 92 versus 86.2%.

CONCLUSION

68GaPSMA PET/CT demonstrated a good diagnostic accuracy as a single procedure for the diagnosis and staging of high-risk PCa.

Targeted prostate biopsy: 68Ga-PSMA PET/CT vs. mpMRI in the diagnosis of prostate cancer

Introduction: To evaluate the diagnostic accuracy of 68Ga-prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomog-raphy (PET/CT) vs. multiparametric magnetic resonance imag-ing (mpMRI) targeted biopsy (TPBx) in the diagnosis of clinical-ly significant prostate cancer (csPCa: Grade Group ≥ 2). Materials and methods: From January 2021 to June 2022, 100 patients (median age: 66 years) with negative digital rectal examination underwent transperineal prostate biopsy for abnor-mal PSA values (median 7.5 ng/ml). Before prostate biopsy, all patients underwent mpMRI and 68Ga-PET/CT examinations and mpMRI (PI-RADS version 2 ≥ 3) or 68Ga-PET/CT index lesions suspicious for cancer (SUVmax > 5 g/ml) underwent cognitive targeted cores (mpMRI-TPBx and PSMA-TPBx: four cores) com-bined with extended systematic prostate biopsy (eSPBx: median 18 cores). The procedure was performed transperineally using a tru-cut 18-gauge needle under sedation and antibiotic prophy-laxis. Results: PCa was found in 58/100 (58.0%) men; in detail, 44/58 (75.9%) were csPCa; mpMRI and 68Ga-PSMA showed 66/100 (66%) and 62/100 (60%) lesions suspicious for PCa, respective-ly. 68Ga-PSMA-TPBx vs. mpMRI-TPBx vs. eSPBx diagnosed 42 (95.4%) vs. 36 (81.8%) vs. 30 (68.2%) csPCa, respectively; mpMRI-TPBx vs. 68Ga-PSMA-TPBx showed a diagnostic accuracy of 76.9% vs. 84.9% in diagnosing csPCa. Conclusions: 68GaPSMA PET/CT TPBx demonstrated good accuracy in the diagnosis of csPCa, which was not inferior to mpMRI TPBx (84.9% vs. 76.9%) improving the detection rate for cancer of systematic biopsy.

Could 68Ga-PSMA PET/CT Evaluation Reduce the Number of Scheduled Prostate Biopsies in Men Enrolled in Active Surveillance Protocols?

Background: To evaluate the accuracy of 68Ga-prostate specific membrane antigen (PSMA) PET/CT in the diagnosis of clinically significant prostate cancer (csPCa) (Grade Group > 2) in men enrolled in Active Surveillance (AS) protocol. Methods: From May 2013 to May 2021, 173 men with very low-risk PCa were enrolled in an AS protocol study. During the follow-up, 38/173 (22%) men were upgraded and 8/173 (4.6%) decided to leave the AS protocol. After four years from confirmatory biopsy (range: 48−52 months), 30/127 (23.6%) consecutive patients were submitted to mpMRI and 68Ga-PSMA PET/CT scan before scheduled repeated biopsy. All the mpMRI (PI-RADS > 3) and 68Ga-PET/TC standardised uptake value (SUVmax) > 5 g/mL index lesions underwent targeted cores (mpMRI-TPBx and PSMA-TPBx) combined with transperineal saturation prostate biopsy (SPBx: median 20 cores). Results: mpMRI and 68Ga-PSMA PET/CT showed 14/30 (46.6%) and 6/30 (20%) lesions suspicious for PCa. In 2/30 (6.6%) men, a csPCa was found; 68Ga-PSMA-TPBx vs. mpMRI-TPBx vs. SPBx diagnosed 1/2 (50%) vs. 1/2 (50%) vs. 2/2 (100%) csPCa, respectively. In detail, mpMRI and 68Ga-PSMA PET/TC demonstrated 13/30 (43.3%) vs. 5/30 (16.7%) false positive and 1 (50%) vs. 1 (50%) false negative results. Conclusion: 68Ga-PSMA PET/CT did not improve the detection for csPCa of SPBx but would have spared 24/30 (80%) scheduled biopsies showing a lower false positive rate in comparison with mpMRI (20% vs. 43.3%) and a negative predictive value of 85.7% vs. 57.1%, respectively.