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

Prostate-specific membrane antigen PET versus [99mTc]Tc-MDP bone scan for diagnosing bone metastasis in prostate cancer: a head-to-head comparative meta-analysis

PURPOSE

To evaluate the diagnostic performance of PSMA PET/CT, including [68Ga]Ga-PSMA-11 and [18F]DCFPyL, in comparison with the [99mTc]Tc-MDP bone scan (BS) in identifying bone metastases among prostate cancer patients.

METHODS

A search was performed in the PubMed and Embase databases to locate pertinent publications from inception to February 12, 2024. The studies included were those that examined the diagnostic effectiveness of PSMA PET/CT (covering [68Ga]Ga-PSMA-11 and [18F]DCFPyL) compared to [99mTc]Tc-MDP BS in identifying bone metastases among prostate cancer patients. The quality of the selected studies was evaluated using the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) checklist.

RESULTS

The meta-analysis included nine articles involving 702 patients. The sensitivity of PSMA PET/CT was higher compared to [99mTc]Tc-MDP BS (0.98 vs. 0.85, P < 0.01), while the specificity of PSMA PET/CT was also higher than [99mTc]Tc-MDP BS (0.97 vs. 0.70,P < 0.01). In subgroup analysis, the sensitivity of [68Ga]Ga-PSMA-11 PET/CT was higher compared to [99mTc]Tc-MDP BS (0.98 vs. 0.86), while the specificity of [68Ga]Ga-PSMA-11 PET/CT was also higher than [99mTc]Tc-MDP BS (0.98 vs. 0.65).

CONCLUSION

Our meta-analysis demonstrates that PSMA PET/CT exhibits superior sensitivity and specificity in comparison with [99mTc]Tc-MDP BS for identifying bone metastases in prostate cancer patients. Further research with head-to-head design is necessary to validate these results and evaluate the clinical effectiveness of these imaging methods.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero/, identifier PROSPERO CRD42024545112.

The diagnostic accuracy of 68Ga-PSMA PET/CT versus 99mTc-MDP bone scintigraphy for identifying bone metastases in persons with prostate cancer: A systematic review

INTRODUCTION

Prostate cancer (PCa) is the second most common cause of cancer related death in men. Accurate diagnosis of bone metastases is essential to treatment decision-making and follow-up. Recent primary studies have compared the accuracy of 68Ga-PSMA PET/CT versus 99mTc-MDP bone scintigraphy in the detection of PCa bone metastases. These studies suggest 68Ga-PSMA PET/CT to be superior. Comprehensive syntheses of these studies are now warranted.

PURPOSE

To synthesize studies comparing the accuracy of 68Ga-PSMA PET/CT versus 99mTc-MDP bone scintigraphy, the most used modality in the identification of bone metastases in PCa patients.

METHODS

A systematic review was conducted evaluating diagnostic accuracy studies which compared 68Ga-PSMA PET/CT and 99mTc-MDP bone scintigraphy. Bias and quality were assessed using the QUADAS-2 tool. Searches in three databases using search terms: Positron-Emission Tomography, prostatic neoplasm, 68Ga, and bone were conducted. Image acquisitions between modalities had to be performed within 3 months of each other.

RESULTS

Five single-centered studies were included in this review. Across all measures of accuracy, 68Ga PSMA PET/CT was superior to 99mTc-MDP bone scintigraphy in the detection of skeletal metastases. Patient-based sensitivities and specificities across included studies ranged from (91%-100% vs. 50%-91%) and (88%-100% vs 19%-96%) for 68Ga-PSMA PET/CT and 99mTc-MDP bone scintigraphy respectively. The overall risk of bias was moderate primarily due to the retrospective nature of most included studies.

CONCLUSION

68Ga-PSMA PET/CT was more accurate than 99mTc-MDP bone scintigraphy in the detection of PCa bone metastases. Future studies should seek to define the clinical relevance of these findings.

Head-To-Head Comparison of 68Ga-PSMA-11 PET/CT and 99mTc-MDP Bone Scintigraphy for the Detection of Bone Metastases in Patients With Prostate Cancer: A Meta-Analysis

BACKGROUND. Bone scintigraphy (BS) using 99mTc-labeled methylene diphospho-nate (99mTc-MDP) remains the recommended imaging modality for the detection of bone metastases in patients with prostate cancer (PCa). However, PET/CT using prostate-specific membrane antigen (PSMA) ligands is increasingly recognized as a means of evaluating disease extent in patients with PCa, including use as a possible stand-alone test in high-risk patients. OBJECTIVE. The purpose of this study is to compare the diagnostic performance of 68Ga-PSMA-11 PET/CT with that of 99mTc-MDP BS for the detection of bone metastases in patients with PCa. EVIDENCE ACQUISITION. The PubMed, Embase, and Cochrane Library databases were searched through October 2021 to identify studies reporting a head-to-head comparison of 68Ga-PSMA-11 PET/CT and 99mTc-MDP BS for the detection of bone metastases in patients with PCa. Only studies with a well-defined reference standard (including various combinations of imaging and/or clinical follow-up) were included. Pooled diagnostic performance was calculated using a bivariate random-effects model, and an AUC was derived for each test from hierarchic summary ROC analysis. The complementary roles of the two tests in identifying bone metastases in patients in whom one of the tests was negative were summarized. EVIDENCE SYNTHESIS. Six studies with 546 patients were included. Pooled sensitivity and specificity, respectively, were 98% (95% CI, 94-99%) and 97% (95% CI, 91-99%) for 68Ga-PSMA-11 PET/CT versus 83% (95% CI, 69-91%) and 68% (95% CI, 41-87%) for 99mTc-MDP BS. The AUC was 0.99 (95% CI, 0.96-1.00) for 68Ga-PSMA-11 PET/CT and 0.85 (95% CI, 0.81-0.87) for 99mTc-MDP BS. Among 408 patients from five included studies, 68Ga-PSMA-11 PET/CT correctly identified bone metastases in 43 of 193 patients (22.3%) with negative 99mTc-MDP BS results, whereas 99mTc-MDP BS correctly identified bone metastases in four of 210 patients (1.9%) with negative 68Ga-PSMA-11 PET/CT results. CONCLUSION. On a per-patient basis, the diagnostic performance of 68Ga-PSMA-11 PET/CT is superior to that of 99mTc-MDP BS for the detection of PCa bone metastases. Furthermore, 99mTc-MDP BS offers limited additional information in patients with negative 68Ga-PSMA-11 PET/CT results. CLINICAL IMPACT. According to current evidence, 99mTc-MDP BS is highly unlikely to be additive to 68Ga-PSMA-11 PET/CT in identifying bone metastases in patients with PCa.

Prostate specific membrane antigen positron emission tomography in primary prostate cancer diagnosis: First-line imaging is afoot

Prostate specific membrane antigen positron emission tomography (PSMA PET) is an excellent molecular imaging technique for prostate cancer. Currently, PSMA PET for patients with primary prostate cancer is supplementary to conventional imaging techniques, according to guidelines. This supplementary function of PSMA PET is due to a lack of systematic review of its strengths, limitations, and potential development direction. Thus, we review PSMA ligands, detection, T, N, and M staging, treatment management, and false results of PSMA PET in clinical studies. We also discuss the strengths and challenges of PSMA PET. PSMA PET can greatly increase the detection rate of prostate cancer and accuracy of T/N/M staging, which facilitates more appropriate treatment for primary prostate cancer. Lastly, we propose that PSMA PET could become the first-line imaging modality for primary prostate cancer, and we describe its potential expanded application.

Characterizing and quantifying low-value diagnostic imaging internationally: a scoping review

BACKGROUND

Inappropriate and wasteful use of health care resources is a common problem, constituting 10-34% of health services spending in the western world. Even though diagnostic imaging is vital for identifying correct diagnoses and administrating the right treatment, low-value imaging-in which the diagnostic test confers little to no clinical benefit-is common and contributes to inappropriate and wasteful use of health care resources. There is a lack of knowledge on the types and extent of low-value imaging. Accordingly, the objective of this study was to identify, characterize, and quantify the extent of low-value diagnostic imaging examinations for adults and children.

METHODS

A scoping review of the published literature was performed. Medline-Ovid, Embase-Ovid, Scopus, and Cochrane Library were searched for studies published from 2010 to September 2020. The search strategy was built from medical subject headings (Mesh) for Diagnostic imaging/Radiology OR Health service misuse/Medical overuse OR Procedures and Techniques Utilization/Facilities and Services Utilization. Articles in English, German, Dutch, Swedish, Danish, or Norwegian were included.

RESULTS

A total of 39,986 records were identified and, of these, 370 studies were included in the final synthesis. Eighty-four low-value imaging examinations were identified. Imaging of atraumatic pain, routine imaging in minor head injury, trauma, thrombosis, urolithiasis, after thoracic interventions, fracture follow-up and cancer staging/follow-up were the most frequently identified low-value imaging examinations. The proportion of low-value imaging varied between 2 and 100% inappropriate or unnecessary examinations.

CONCLUSIONS

A comprehensive list of identified low-value radiological examinations for both adults and children are presented. Future research should focus on reasons for low-value imaging utilization and interventions to reduce the use of low-value imaging internationally.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO: CRD42020208072.

Salvage therapy for prostate cancer after radical prostatectomy

More than 40% of men with intermediate-risk or high-risk prostate cancer will experience a biochemical recurrence after radical prostatectomy. Clinical guidelines for the management of these patients largely focus on the use of salvage radiotherapy with or without systemic therapy. However, not all patients with biochemical recurrence will go on to develop metastases or die from their disease. The optimal pre-salvage therapy investigational workup for patients who experience biochemical recurrence should, therefore, include novel techniques such as PET imaging and genomic analysis of radical prostatectomy specimen tissue, as well as consideration of more traditional clinical variables such as PSA value, PSA kinetics, Gleason score and pathological stage of disease. In patients without metastatic disease, the only known curative intervention is salvage radiotherapy but, given the therapeutic burden of this treatment, importance must be placed on accurate timing of treatment, radiation dose, fractionation and field size. Systemic therapy also has a role in the salvage setting, both concurrently with radiotherapy and as salvage monotherapy.

Prostate-specific Membrane Antigen-based Imaging of Castration-resistant Prostate Cancer

CONTEXT

Positron emission tomography (PET) targeting prostate-specific membrane antigen (PSMA) has unprecedented accuracy for localization of initial or recurrent prostate cancer (PC). There is now growing evidence regarding the value of PSMA-PET in patients with advanced PC.

OBJECTIVE

To review the value of PSMA-PET/computed tomography (CT) in the context of castration-resistant PC (CRPC).

EVIDENCE ACQUISITION

A search of the PubMed database using the terms "PSMA PET castration resistant prostate cancer" (years 2011-2020) was performed. Reviews, case reports/series, non-English articles, preclinical studies, access-restricted studies, and studies on PSMA radioligand therapy without further analysis of PSMA-PET parameters were subsequently excluded.

EVIDENCE SYNTHESIS

Compared to conventional imaging, PSMA-PET better identifies the true extent of CRPC, especially nonmetastatic CRPC. The clinical benefit of this stage migration is still unclear and needs to be evaluated in further studies. High accuracy of PSMA-PET holds promise for better, PET-guided metastasis-directed treatment in patients with oligometastatic CRPC. PSMA-PET is an essential eligibility criterion for [¹⁷⁷Lu]-PSMA theranostic applications. Preliminary evidence indicates the value of PSMA-PET for the assessment of treatment responses.

CONCLUSIONS

Among other applications, PSMA-PET offers more precise staging for nonmetastatic CRPC. In particular, target localization for metastasis-directed therapy and target expression assessment for PSMA radioligand therapy also hold promise. Potential translation of this diagnostic tool into an oncologic benefit needs to be defined in future trials.

PATIENT SUMMARY

This review describes how prostate-specific membrane antigen positron emission tomography (PSMA-PET), a new sensitive imaging tool for prostate cancer, might help to guide clinicians in making treatment decisions for advanced prostate cancer.

Does bone scintigraphy still have a role in the era of 68 Ga-PSMA PET/CT in prostate cancer?

OBJECTION

We aimed to evaluate the role of bone scintigraphy (BS) which has long been the imaging modality of choice in prostate cancer (PCa) and performed a head-to-head comparison between BS, BS + SPECT/CT and 68 Ga-PSMA-PET/CT, for the detection of bone metastasis of PCa.

METHODS

We evaluated 138 PCa patients who underwent BS and 68 Ga-PSMA PET/CT and SPECT/CT of 102 of 138 patients. Images were interpreted retrospectively and areas of abnormally increased tracer uptake related to PCa were documented as benign, metastatic or equivocal. Equivocal uptakes were finally diagnosed based on a consensus review of correlative imaging. Patient- and lesion-based analysis was performed. Patients with superscan images were excluded from lesion-based analysis.

RESULTS

At least one metastatic or equivocal uptake in skeleton was defined in 76 of 138 (55%) BS, in 33 of 102 (32.3%) SPECT/CT, and in 49 of 138 (35.5%) 68 Ga-PSMA PET/CT. 23 (16.7%) patients had also superscan findings on BS and 68 Ga-PSMA PET/CT. For patient-based analysis, sensitivity, specificity, accuracy, PPV, and NPV were calculated as 91.1%, 64.5%, 73.1%, 55.4% and 93.7% for BS; 95.5%, 82.7%, 86.9%, 72.8% and 96.2% for BS + SPECT/CT; 97.7%, 95.7%, 95.6%, 91.6% and 98.8% for 68 Ga-PSMA PET/CT. For lesion-based analysis, sensitivity, specificity, accuracy, PPV, and NPV were 53%, 63.9%, 60.1%, 42.8% and 71.8% for BS; 59.2%, 87.6%, 77.7%, 62.6% and 80% for BS + SPECT/CT; 96.4%, 98.1%, 97.5%, 96.4% and 98.1% for 68 Ga-PSMA PET/CT.

CONCLUSION

This study has shown that 68 Ga-PSMA PET/CT overcomes the limitations of BS and proves superiority in detecting bone metastases, even in patients with SPECT/CT. Our findings present important implications that 68 Ga-PSMA PET/CT can replace BS in future practice.