Novel PET imaging methods for prostate cancer

Discrepancy in the Location of Prostate Cancer Indicated on Biparametric Magnetic Resonance Imaging and Pathologically Diagnosed Using Surgical Specimens

Accurate diagnosis of the localization of prostate cancer (PCa) on magnetic resonance imaging (MRI) remains a challenge. We aimed to assess discrepancy between the location of PCa pathologically diagnosed using surgical specimens and lesions indicated as possible PCa by the Prostate Imaging Reporting and Data System on MRI. The primary endpoint was the concordance rate between the site of probable clinically significant PCa (csPCa) identified using biparametric MRI (bpMRI) and location of PCa in the surgical specimen obtained using robot-assisted total prostatectomy. Among 85 lesions identified in 30 patients; 42 (49.4%) were identified as possible PCa on MRI. The 85 PCa lesions were divided into positive and negative groups based on the bpMRI results. None of the patients had missed csPCa. Although the diagnostic accuracy of bpMRI was relatively high for PCas located in the middle of the prostate (p = 0.029), it was relatively low for PCa located at the base of the prostate, all of which were csPCas. Although current modalities can accurately diagnose PCa, the possibility that PCa is present with multiple lesions in the prostate should be considered, even if MRI does not detect PCa.

Size of lymph-node metastases in prostate cancer patients undergoing radical prostatectomy: implication for imaging and oncologic follow-up of 2705 lymph-node positive patients

BACKGROUND

Despite modern imaging modalities, lymph-node staging before radical prostatectomy (RP) remains challenging in patients with prostate cancer (PCa). The visibility of lymph-node metastases (LNMs) is critically influenced by their size.

OBJECTIVE

This study aims to describe the distribution of maximal tumor diameters (i.e., size) in LNMs of pN1-PCa at RP and its consequences on visibility in preoperative imaging and oncological outcomes.

DESIGN, SETTING, AND PARTICIPANTS

A total of 2705 consecutive patients with pN1-PCa at RP, harboring a cumulative 7510 LNMs, were analyzed. Descriptive and multivariable analyses addressed the risk of micrometastases (MM)-only disease and the visibility of LNMs. Kaplan-Meier curves and Cox analyses were used for biochemical recurrence-free survival (BCRFS) stratified for MM-only disease.

RESULTS

The median LNM size was 4.5mm (interquartile range (IQR): 2.0-9.0 mm). Of 7510 LNMs, 1966 (26%) were MM (≤ 2mm). On preoperative imaging, 526 patients (19%) showed suspicious findings (PSMA-PET/CT: 169/344, 49%). In multivariable analysis, prostate-specific antigen (PSA) (OR 0.98), age (OR 1.01), a Gleason score greater than 7 at biopsy (OR 0.73), percentage of positive cores at biopsy (OR 0.36), and neoadjuvant treatment (OR 0.51) emerged as independent predictors for less MM-only disease (p < 0.05). Patients with MM-only disease compared to those harboring larger LNMs had a longer BCRFS (median 60 versus 29 months, p < 0.0001).

CONCLUSION

Overall, 26% of LNMs were MM (≤ 2mm). Adverse clinical parameters were inversely associated with MM at RP. Consequently, PSMA-PET/CT did not detect a substantial proportion of LNMs. LNM size and count are relevant for prognosis.

Stereotactic Body Radiation Therapy Salvage for Lymph Node Recurrent Prostate Cancer in the Era of PSMA PET Imaging

PURPOSE OF REVIEW

Our understanding of patterns of prostate cancer recurrence after primary treatment of localized disease has significantly evolved since the development of positron emission tomography (PET) agents targeting prostate cancer. Previously, most biochemical recurrences were not associated with imaging correlates when restaging with computed tomography (CT), magnetic resonance imaging (MRI), or bone scintigraphy and, hence, were typically assumed to represent occult metastases. A rising prostate specific antigen (PSA) after previous local therapy prompting a PET scan showing uptake limited to regional lymph nodes is an increasingly common clinical scenario as advanced prostate cancer imaging becomes more widely utilized. The optimal management strategy for patients who have lymph node recurrent prostate cancer is both unclear and evolving, particularly in terms of local and regionally directed therapies. Stereotactic body radiation therapy (SBRT) utilizes ablative radiation doses with steep gradients to achieve local tumor control while sparing nearby normal tissues. SBRT is an attractive therapeutic modality due to its efficacy, favorable toxicity profile, and flexibility to administer elective doses to areas of potential occult involvement. The purpose of this review is to briefly describe how SBRT is being implemented in the era of PSMA PET for the management of solely lymph node recurrent prostate cancer.

RECENT FINDINGS

SBRT has been shown to effectively control individual lymph node tumor deposits within the pelvis and retroperitoneum for prostate cancer and is well-tolerated with a favorable toxicity profile. However, a major limitation thus far has been the lack of prospective trials supporting the use of SBRT for oligometastatic nodal recurrent prostate cancer. As further trials are conducted, its exact role in the treatment paradigm of recurrent prostate cancer will be better established. Although PET-guided SBRT appears feasible and potentially beneficial, there is still considerable uncertainty about the use of elective nodal radiotherapy (ENRT) in patients with nodal recurrent oligometastatic prostate cancer. PSMA PET has undoubtedly advanced imaging of recurrent prostate cancer, revealing anatomic correlates for disease recurrence that previously went undetected. At the same time, SBRT continues to be explored in prostate cancer with feasibility, a favorable risk profile, and satisfactory oncologic outcomes. However, much of the existing literature comes from the pre-PSMA PET era and integration of this novel imaging approach has led to greater focus on new and ongoing clinical trials to rigorously evaluate this approach and compare to other established treatment modalities utilized for oligometastatic, nodal recurrence of prostate cancer.

Contemporary Review of Multimodality Imaging of the Prostate Gland

Tissue changes and the enlargement of the prostate, whether benign or malignant, are among the most common groups of diseases that affect men and can have significant impacts on length and quality of life. The prevalence of benign prostatic hyperplasia (BPH) increases significantly with age and affects nearly all men as they grow older. Other than skin cancers, prostate cancer is the most common cancer among men in the United States. Imaging is an essential component in the diagnosis and management of these conditions. Multiple modalities are available for prostate imaging, including several novel imaging modalities that have changed the landscape of prostate imaging in recent years. This review will cover the data relating to commonly used standard-of-care prostate imaging modalities, advances in newer technologies, and newer standards that impact prostate gland imaging.

Underlying Features of Prostate Cancer-Statistics, Risk Factors, and Emerging Methods for Its Diagnosis

Prostate cancer (PCa) is the most frequently occurring type of malignant tumor and a leading cause of oncological death in men. PCa is very heterogeneous in terms of grade, phenotypes, and genetics, displaying complex features. This tumor often has indolent growth, not compromising the patient's quality of life, while its more aggressive forms can manifest rapid growth with progression to adjacent organs and spread to lymph nodes and bones. Nevertheless, the overtreatment of PCa patients leads to important physical, mental, and economic burdens, which can be avoided with careful monitoring. Early detection, even in the cases of locally advanced and metastatic tumors, provides a higher chance of cure, and patients can thus go through less aggressive treatments with fewer side effects. Furthermore, it is important to offer knowledge about how modifiable risk factors can be an effective method for reducing cancer risk. Innovations in PCa diagnostics and therapy are still required to overcome some of the limitations of the current screening techniques, in terms of specificity and sensitivity. In this context, this review provides a brief overview of PCa statistics, reporting its incidence and mortality rates worldwide, risk factors, and emerging screening strategies.

Prostate Cancer-PET Imaging Update

Prostate cancer is the most common non-dermatologic cancer in men, and one of the leading causes of cancer-related mortality. The incidence of prostate cancer increases precipitously after the age of 65 and demonstrates variable aggressiveness, depending on its grade and stage at diagnosis. Despite recent advancements in prostate cancer treatment, recurrence is seen in 25% of patients. Advancements in prostate cancer Positron Emission Tomography (PET) molecular imaging and recent United States Food and Drug Administration (FDA) approvals have led to several new options for evaluating prostate cancer. This manuscript will review the commonly used molecular imaging agents, with an emphasis on Fluorine-18 fluciclovine (Axumin) and PSMA-ligand agents, including their protocols, imaging interpretation, and pitfalls.

Comparison of 18F-FDG PET/CT imaging with different dual time 18F-FDG PET/CT with forced diuresis in clinical diagnosis of prostate cancer

The aim of this study was to compare the capability of different dual time (interval 1, 2, 3, or 4 hours) 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) with forced diuresis to diagnose prostate cancer (PCa). A retrospective review of 273 male patients from March 2009 to June 2019, with any focal 18F-FDG uptake in the prostate gland during PET/CT imaging. Early PET/CT imaging was performed 60 minutes after FDG injection. Delayed imaging was performed 1 to 4 hours after diuretic injection. For prostate lesions with increased 18F-FDG uptake, a spheroid-shaped volume of interest was drawn, including the entire lesion, and the maximum standard uptake value (SUVmax) of the lesion was measured. The SUVmax > 2.5 after delayed imaging and the retention index > 15% were used as the diagnostic criteria for PET/CT in the diagnosis of PCa. Otherwise, it was diagnosed as the benign prostate disease. The final diagnosis was based on histological examination, associated imaging studies, or/and clinical follow-up. The results of inter-group comparison showed that the SUVmax of 1-, 2-, 3-, and 4-hour delayed imaging after diuresis in PCa group was significantly higher than that in control group (P < .05), but there was no statistical difference in SUVmax of early imaging between PCa and control group (P > .05). And the retention index of PCa group that delayed 1, 2, 3, and 4 hours after diuresis were significantly higher than those of control group, respectively (P < .05). The diagnostic sensitivity of imaging delayed 1, 2, 3, and 4 hours after diuresis was 68.8%, 81.2%, 85.7 %, and 71.4%, the specificity was 52.5%, 74.5%, 70.6%, and 65.0%, and the accuracy was respectively 58.2%, 77.4%, 76.4%, and 67.6%, the positive predictive values were 44.0%, 68.9%, 64.3%, and 58.8%, and the negative predictive value were 75.6%, 85.4%, 88.9%, and 76.5%, respectively. 18F-FDG PET/CT imaging as an imaging tool lacks certain specificity in the diagnosis of PCa, regardless of whether the imaging is delayed. The main advantage of delayed diuretic imaging in PCa is that it can significantly improve the sensitivity, especially the diagnostic effect delayed 2 hours after diuresis is better.

PSMA-11 PET/CT for Detection of Recurrent Prostate Cancer in Patients With Negative Choline PET/CT

INTRODUCTION

Prostate adenocarcinoma (CaP) is the leading cancer in men. After curative treatment, from 27% to 53% of patients will experience biochemical recurrence (BR). With the development of focal therapies, precise early identification of recurrence's sites is of utmost importance in order to deliver individualized treatment on positive lesions. The aim of this study was to assess the detection rate (DR) of ⁶⁸Ga-PSMA-11 positron emission tomography/computed tomography (PET/CT) in selected patients with prostate cancer BR and recent negative ¹⁸F-choline PET/CT.

PATIENTS AND METHODS

We performed a retrospective analysis including all patients with CaP referred for BR with a negative ¹⁸F-choline PET/CT, and who underwent ⁶⁸Ga-PSMA-11 PET/CT between October, 2018 and December, 2019. The overall DR of ⁶⁸Ga-PSMA-11 PET/CT was calculated, and described according to BR characteristics especially PSA levels and velocity. Patients were followed up for at least 1 year. Patient management following ⁶⁸Ga-PSMA-11 PET/CT and PSA levels evolution after treatment were also recorded.

RESULTS

One hundred fifty-nine patients comprising 164 examinations were analyzed. The overall DR of ⁶⁸Ga-PSMA-11 PET/CT for BR was 65.9% (95CI, 58.6-73.1). The DR was 52.5% (95CI, 39.9-65.0), 70.6% (95CI, 55.3-85.9), 70.4% (95CI, 53.1-87.6), and 78.6% (95CI, 66.2-91.0) for PSA levels between 0.2 and 0.49 ng/mL, 0.5 to 0.99 ng/mL, 1 to 1.99 ng/mL and PSA ≥ 2 ng/mL, respectively. The DR was 70.7% (95CI, 59.0-82.4) with a PSA doubling time (PSA-DT) ≤6 months and 65.2% (95CI, 55.5-74.9) with a PSA-DT >6 months. Around 3/4 of patients (75.9%) with a positive ⁶⁸Ga-PSMA-11 PET/CT initiated treatment, including surgery (2.4%), stereotactic radiotherapy ± androgen deprivation therapy (ADT) (22%) or external conformational radiotherapy ± ADT (46.3%). Patient management changed in 43 cases (39.8%).

CONCLUSION

Our study confirmed the ability of ⁶⁸Ga-PSMA-11 PET/CT to detect occult biochemical recurrence, even in a selected population of CaP patients with negative ¹⁸F-choline PET/CT, even at low PSA levels.

Recent Advances in Cardiovascular Diseases Research Using Animal Models and PET Radioisotope Tracers

Cardiovascular diseases (CVD) is a collective term describing a range of conditions that affect the heart and blood vessels. Due to the varied nature of the disorders, distinguishing between their causes and monitoring their progress is crucial for finding an effective treatment. Molecular imaging enables non-invasive visualisation and quantification of biological pathways, even at the molecular and subcellular levels, what is essential for understanding the causes and development of CVD. Positron emission tomography imaging is so far recognized as the best method for in vivo studies of the CVD related phenomena. The imaging is based on the use of radioisotope-labelled markers, which have been successfully used in both pre-clinical research and clinical studies. Current research on CVD with the use of such radioconjugates constantly increases our knowledge and understanding of the causes, and brings us closer to effective monitoring and treatment. This review outlines recent advances in the use of the so-far available radioisotope markers in the research on cardiovascular diseases in rodent models, points out the problems and provides a perspective for future applications of PET imaging in CVD studies.

Role of molecular imaging in the detection of localized prostate cancer

Molecular imaging of prostate cancer continues to grow, with recent inclusion of several positron emission tomography (PET) radiotracers into the recent National Comprehensive Cancer Network guidelines and the US Food and Drug Administration approval of prostate-specific membrane antigen (PSMA)-targeted radiotracers. While much of the work for many of these radiotracers is focused on systemic staging and restaging in both newly diagnosed high-risk prostate cancer and biochemically recurrent disease patients, the potential role of molecular imaging for the detection of localized prostate cancer has not yet been fully established. The primary aim of this article will be to present the potential role for molecular imaging in the detection of localized prostate cancer and discuss potential advantages and disadvantages to utilization of both PET/computed tomography (CT) and PET/magnetic resonance imaging (MRI) for this clinical indication of use.

[Innovative laser technologies in the treatment of urolithiasis : A change to more gentle methods with increased patient safety]

Management of urolithiasis has undergone fundamental changes with the introduction of extracorporeal shock wave lithotripsy (ESWL) and percutaneous and ureterorenoscopic techniques in the 1980s. Since then, these minimally invasive techniques have been continuously optimized and specific laser techniques for stone disintegration have emerged. Besides the established holmium laser, other types of lasers are also emerging. Especially the thulium fiber laser is the subject of promising research due to its variable adjustment options. In terms of patient safety, both holmium and thulium techniques seem to be similar . While serious direct physical lesions are rare, there is increasing evidence of clinically relevant secondary thermal injury due to increased temperatures in the upper urinary tract during treatment. Our research group has recently demonstrated in both in vitro and in vivo (porcine animal model) experiments that monitoring the fluorescence spectra of calculi allows precise target differentiation between stone, tissue, and endoscope components. Consequently, pulse emissions were only emitted when stone material was detected. We believe that target monitoring will minimize the risk of laser-induced urothelial damage and decrease energy release into the upper urinary tract allowing adequate temperature management.