Bone scintigraphy as a gatekeeper for the detection of bone metastases in patients with prostate cancer: comparison with Ga-68 PSMA PET/CT

Physiological biodistribution on Ga68-PSMA PET/CT and the factors effecting biodistribution

AIM

The study aims to determine the physiological and pathophysiological distribution of the radiopharmaceutical (Ga68-PSMA-617) and investigate whether there are differences in distribution according to the laboratory, histopathological and clinical findings that can affect image evaluation. Also, we aimed to determine cut-off values to distinguish physiological and pathological uptake in prostate, bone, and lymph nodes.

MATERIALS AND METHODS

229 prostate cancer patients who underwent Ga68-PSMA PET/CT at our department were retrospectively analyzed. The patients were grouped according to PET/CT results, Gleason scores, PSA values, received treatments, metastatic status and other laboratory values. The SUV values of the organs, tissues, and pathological lesions of the patients in these subgroups were compared among themselves.

RESULTS

No significant difference was detected in the physiological uptake of lymph nodes and bone between the groups. In the group with patients that received androgen deprivation therapy (ADT), the bone metastasis SUV values were found to be higher and the SUV values of the submandibular gland and renal cortex were found to be lower (Mann-Whitney U, p = 0.043; 0.004; 0.01, respectively). In the group with patients who received radiotherapy, the normal prostate tissue SUV values were determined to be higher (Mann-Whitney U, p = 0.009). The SUV values of the submandibular gland, muscle, liver, and blood pool were found to be lower in the group of patients with high serum LDH values. The cut-off SUVmax value was determined to be 6.945 (sensitivity 89.6%, specificity 98.1%) for primary prostate lesion; 4.72 for lymph node metastasis; 4.25 for bone metastasis. The serum PSA cut-off value to distinguish the negative/positive groups was found to be 1,505 (sensitivity 79.7%, specificity 77.3%).

CONCLUSION

In conclusion, PSMA-617 demonstrates a similar biodistribution with other PSMA ligands. The physiological uptake of lymph nodes and bone which are mostly metastasized in prostate cancer, are not affected by the factors we examined. It should be kept in mind that the normal prostate tissue uptake may increase in patients receiving radiotherapy, and the physiological/pathological uptake of the organs may differ due to the changes in PSMA expression in patients receiving ADT, tumor burden, and kidney function may affect the biodistribution.

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.

The Role of [18F]F-Choline PET/CT in the Initial Management and Outcome Prediction of Prostate Cancer: A Real-World Experience from a Multidisciplinary Approach

Initial staging of prostate cancer (PCa) is usually performed with conventional imaging (CI), involving computed tomography (CT) and bone scanning (BS). The aim of this study was to analyze the role of [¹⁸F]F-choline positron emission tomography (PET)/CT in the initial management and outcome prediction of PCa patients by analyzing data from a multidisciplinary approach. We retrospectively analyzed 82 patients who were discussed by the uro-oncology board of the University Hospital of Ferrara for primary staging newly diagnosed PCa (median age 72 (56-86) years; median baseline prostate specific antigen (PSA) equal to 8.73 ng/mL). Patients were divided into three groups based on the imaging performed: group A = only CI; group B = CI + [¹⁸F]F-choline PET/CT; group C = only [¹⁸F]F-choline PET/CT. All data on imaging findings, therapy decisions and patient outcomes were retrieved from hospital information systems. Moreover, we performed a sub-analysis of semiquantitative parameters extracted from [¹⁸F]F-choline PET/CT to search any correlation with patient outcomes. The number of patients included in each group was 35, 35 and 12, respectively. Patients with higher values of initial PSA were subjected to CI + PET/CT (p = 0.005). Moreover, the use of [¹⁸F]F-choline PET/CT was more frequent in patients with higher Gleason score (GS) or ISUP grade (p = 0.013). The type of treatment performed (surgery n = 33; radiation therapy n = 22; surveillance n = 6; multimodality therapy n = 6; systemic therapy n = 13; not available n = 2) did not show any relationship with the modality adopted to stage the disease. [¹⁸F]F-choline PET/CT induced a change of planned therapy in 5/35 patients in group B (14.3%). Moreover, patients investigated with [¹⁸F]F-choline PET/CT alone demonstrated longer biochemical recurrence (BCR)-free survival (30.8 months) in comparison to patients of groups A and B (15.5 and 23.5 months, respectively, p = 0.006), probably due to a more accurate selection of primary treatment. Finally, total lesion choline kinase activity (TLCKA) of the primary lesion, calculated by multiplying metabolic tumor volume and mean standardized uptake value (SUVmean), was able to more effectively discriminate patients who had recurrence after therapy compared to those without (p = 0.03). In our real-world experience [¹⁸F]F-choline PET/CT as a tool for the initial management of PCa had a relevant impact in terms of therapy selection and was associated with longer BCR-free survival. Moreover, TLCKA of the primary lesion looks a promising parameter for predicting recurrence after curative therapy.

Segmented linear correlations between bone scan index and prostate cancer biomarkers, alkaline phosphatase, and prostate specific antigen in patients with a Gleason score ≥7

Technetium-99m methyl diphosphonate bone scintigraphy is relatively easily accessible for detecting bone metastases in prostate cancer patients. However, it is subjective and can be challenging to compare images taken at different time points. The bone scan index (BSI) is a more objective evaluation and allows for better comparison of images. Its correlation with other biomarkers of prostate cancer metastases such as prostate specific antigen (PSA) and alkaline phosphatase (ALP) is not clearly understood. This study thus aimed to compare the BSI correlation to PSA against that of BSI to ALP levels in patients with a Gleason score ≥7.A retrospective analysis of the medical records of 50 prostate cancer patients with a Gleason score of ≥7 referred for a bone scan between January 1, 2015 and December 31, 2018 was undertaken. Bone scans were interpreted visually, and using a semi-automated computer programme to quantify the BSI and its relation to PSA and ALP measurements.For the metastasis positive measurements, there was a statistically significant moderate positive overall linear correlation between BSI and PSA. For ALP and BSI, there were 2 segmented strong positive linear relationships between them. The first segment consisted of ALP < 375 IU/L and BSI >10%, where ALP and BSI were strongly and positively correlated. The other segment tended to have generally low BSI measurements (<10%) and also had a strong and positive correlation.The BSI was found to be better linearly correlated with ALP than PSA.

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-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 for evaluating disease extent in patients with PCa, including as a possible standalone test in high-risk patients. Objective: To compare the diagnostic performance of 68Ga-PSMA-PET/CT and 99mTc-MDP BS for the detection of bone metastases in patients with PCa. Evidence Acquisition: PubMed, Embase, and Cochrane Library databases were searched through October 2021 for studies reporting a head-to-head comparison of 68Ga-PSMA-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 bivariate random-effects model, and AUC was derived for each test from hierarchical summary ROC analysis. The two tests' complementary roles in identifying bone metastases in patients in whom the other test was negative were summarized. Evidence Synthesis: Six studies with 546 patients were included. The pooled sensitivity and specificity 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. In 408 patients from five included studies, 68Ga-PSMA-11 PET/CT correctly identified bone metastases in 43 (22.3%) of 193 patients with negative 99mTc-MDP BS results, whereas 99mTc-MDP BS correctly identified bone metastases in 4 (1.9%) of 210 patients with negative 68Ga-PSMA-11 PET/CT results. Conclusion: On a per-patient basis, 68Ga-PSMA-11 PET/CT has superior diagnostic performance than 99mTc-MDP BS for the detection of prostate cancer 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 prostate cancer.

[Skull base metastases with cranial nerve deficits : Clinical profile of a severe disease]

Hintergrund und Ziele

Schädelbasismetastasen sind eine seltene Manifestation onkologischer Erkrankungen. Wenn Hirnnerven beteiligt sind, können schon kleine Läsionen erhebliche funktionelle Beeinträchtigungen hervorrufen. Spezifische klinische Charakteristika wie neurologische Symptome, assoziierte Primärtumoren, Prognose und optimale Therapie der Erkrankung sind schlecht definiert und sollen in dieser Arbeit systematisch dargestellt werden.

Methoden

Mit einem monozentrischen retrospektiven Ansatz wurden Schädelbasismetastasen bei Patienten, die im Zeitraum von 2006 bis 2018 behandelt wurden, detailliert hinsichtlich klinischer Charakteristika, der durchgeführten Therapie und des weiteren Erkrankungsverlaufs analysiert.

Ergebnisse

Insgesamt 45 Patienten mit Schädelbasismetastasen und Hirnnervenausfällen wurden erfasst. Die häufigsten Primärtumoren waren Prostatakarzinom (27 %), Mammakarzinom (22 %) und multiples Myelom (16 %). Die am häufigsten betroffenen Hirnnerven waren Nervus trigeminus (42 %), Nervus oculomotorius (33 %) und Nervus facialis (27 %). 84 % aller Patienten wiesen außerhalb der Schädelbasis liegende weitere Knochenmetastasen auf. Eine durale Infiltration oder eine Meningeosis neoplastica lagen bei je 13 % der Patienten vor. Nach Bestrahlung waren 61 % der Patienten hinsichtlich der auf die Schädelbasismetastase zurückzuführenden Symptome klinisch stabil, bei 22 % hatten sich die Symptome gebessert. Das mediane Gesamtüberleben betrug 8 Monate (Spanne: 0,4–51 Monate). Bei Patienten, die mit einer dosiseskalierten Bestrahlung behandelt wurden, bestand eine längere Überlebenszeit (16,4 Monate vs. 4,7 Monate). Dieser Effekt persistierte auch in der multivariaten Analyse unter Berücksichtigung der Faktoren Karnofsky-Index, Metastasenanzahl, Primärtumor und Bestrahlungsdosis (HR 0,37, p = 0,02).

Diskussion

Schädelbasismetastasen mit Hirnnervenausfällen haben ein vielgestaltiges Bild und oft eine schlechte Prognose. Um potenziell eine Überlebenszeitverbesserung zu erreichen, sind präzise Diagnostik und Therapie Voraussetzung. Prospektive kontrollierte Untersuchungen sind notwendig.

PSMA PET/CT vs. CT alone in newly diagnosed biochemical recurrence of prostate cancer after radical prostatectomy: Comparison of detection rates and therapeutic implications

OBJECTIVES

To compare prostate specific membrane antigen (PSMA) Positron Emission Tomography/Computed Tomography (PET/CT) and computed tomography (CT) alone for the detection of biochemical recurrence of prostate cancer (PCa) and effect on treatment.

METHODS

This retrospective study included 59 patients with recently recorded biochemical recurrence of PCa (mean PSA 1.96 ± 1.64 ng/mL) after radical prostatectomy. Patients received PET/CT with either ⁶⁸Ga-PSMA-11 (n = 36) or ¹⁸F-PSMA-1007 (n = 23). PET/CT and CT images were evaluated separately in regard to PCa lesion count, type, and localisation by two physicians. Histopathology, follow-up imaging and PSA levels after salvage irradiation served as reference standard. A McNemar test was used to compare detection rates. Changes in therapeutic approaches based on staging differences between CT alone and PET/CT were assessed in a virtual multidisciplinary tumour board.

RESULTS

There were 142 lesions in 50 of 59 patients. PSMA PET/CT detected 141 lesions (99.3 %) in 50 patients (84.7 %), while CT detected 72 lesions (50.7 %) in 29 patients (49.2 %). A significantly higher detection rate of PSMA PET/CT was observed on a lesion-based analysis (p < 0.0001) and on a patient based analysis (p < 0.0001). Herein, both ⁶⁸Ga- and ¹⁸F-PSMA PET/CT performed significantly better than CT alone (p < 0.0001, respectively). In 9 patients (15.3 %) no relapse was detectable by either modality. All lesions detected by CT were also detected by PSMA PET/CT. In 38 patients PSMA PET/CT detected more lesions than CT alone, altering the treatment approach in 22 of these patients.

CONCLUSION

PSMA PET/CT is superior to CT alone in detecting biochemical recurrence in PCa patients after radical prostatectomy and offered additional therapeutic options in a substantial number of patients.