State-of-the-art imaging of prostate cancer

Docetaxel chemotherapy response in PC3 prostate cancer mouse model detected by rotating frame relaxations and water diffusion

MRI is a common method of prostate cancer diagnosis. Several MRI-derived markers, including the apparent diffusion coefficient (ADC) based on diffusion-weighted imaging, have been shown to provide values for prostate cancer detection and characterization. The hypothesis of the study was that docetaxel chemotherapy response could be picked up earlier with rotating frame relaxation times T_RAFF2 and T_RAFF4 than with the continuous wave T_1ρ , adiabatic T_1ρ , adiabatic T_2ρ , T₁ , T₂ or water ADC. Human PC3 prostate cancer cells expressing a red fluorescent protein were implanted in 21 male mice. Docetaxel chemotherapy was given once a week starting 1 week after cell implantation for 10 randomly selected mice, while the rest served as a control group (n = 11). The MRI consisted of relaxation along a fictitious field (RAFF) in the second (RAFF2) and fourth (RAFF4) rotating frames, T₁ and T₂ , continuous wave T_1ρ , adiabatic T_1ρ and adiabatic T_2ρ relaxation time measurements and water ADC. MRI was conducted at 7 T, once a week up to 4 weeks from cell implantation. The tumor volume was monitored using T₂ -weighted MRI and optical imaging. The histology was evaluated after the last imaging time point. Significantly reduced RAFFn, T_1ρ, T_2ρ and conventional relaxation times 4 weeks after tumor implantation were observed in the treated tumors compared with the controls. The clearest short- and long-term responses were obtained with T₁ , while no clear improvement in response to treatment was detected with novel methods compared with conventional methods or with RAFFn compared with all others. The tumor volume decreased after a two-week time point for the treated group and increased significantly in the control group, which was supported by increasing red fluorescent light emission in the control tumors. Decreased relaxation times were associated with successful chemotherapy outcomes. The results indicate altered relaxation mechanisms compared with higher dose chemotherapies previously published.

Computed tomography versus magnetic resonance imaging in high-dose-rate prostate brachytherapy planning: The impact on patient-reported health-related quality of life

PURPOSE

High-dose-rate (HDR) prostate brachytherapy uses volumetric imaging for treatment planning. Our institution transitioned from computed tomography (CT)-based planning to MRI-based planning with the hypothesis that improved visualization could reduce treatment-related toxicity. This study aimed to compare the patient-reported health-related quality of life (hrQOL) and physician-graded toxicity outcomes of CT-based and MRI-based HDR prostate brachytherapy.

METHODS

From 2016 to 2019, 122 patients with low- or intermediate-risk prostate cancer were treated with HDR brachytherapy as monotherapy. Patients underwent CT only or CT and MRI imaging for treatment planning and were grouped per treatment planning imaging modality. Patient-reported hrQOL in the genitourinary (GU), gastrointestinal (GI), and sexual domains was assessed using International Prostate Symptom Score and Expanded Prostate Cancer Index Composite Short Form-26 questionnaires. Baseline characteristics, changes in hrQOL scores, and physician-graded toxicities were compared between groups.

RESULTS

The median follow-up was 18 months. Patient-reported GU, GI, and sexual scores worsened after treatment but returned toward baseline over time. The CT cohort had a lower baseline mean International Prostate Symptom Score (5.8 vs. 7.8, p = 0.03). The other patient-reported GU and GI scores did not differ between groups. Overall, sexual scores were similar between the CT and MRI cohorts (p = 0.08) but favored the MRI cohort at later follow-up with a smaller decrease in Expanded Prostate Cancer Index Composite Short Form-26 sexual score from baseline at 18 months (4.9 vs. 19.8, p = 0.05). Maximum physician-graded GU, GI, and sexual toxicity rates of grade ≥2 were 68%, 3%, and 53%, respectively, with no difference between the cohorts (p = 0.31).

CONCLUSION

Our study shows that CT- and MRI-based HDR brachytherapy results in similar rates of GU and GI toxicity. MRI-based planning may result in improved erectile function recovery compared with CT-based planning.

Radiobiological Characterization of 64CuCl₂ as a Simple Tool for Prostate Cancer Theranostics

⁶⁴CuCl₂ has recently been proposed as a promising agent for prostate cancer (PCa) theranostics, based on preclinical studies in cellular and animal models, and on the increasing number of human studies documenting its use for PCa diagnosis. Nevertheless, the use of ⁶⁴CuCl₂ raises important radiobiological questions that have yet to be addressed. In this work, using a panel of PCa cell lines in comparison with a non-tumoral prostate cell line, we combined cytogenetic approaches with radiocytotoxicity assays to obtain significant insights into the cellular consequences of exposure to ⁶⁴CuCl₂. PCa cells were found to exhibit increased ⁶⁴CuCl₂ uptake, which could not be attributed to increased expression of the main copper cellular importer, hCtr1, as had been previously suggested. Early DNA damage and genomic instability were also higher in PCa cells, with the tumoral cell lines exhibiting deficient DNA-damage repair upon exposure to ⁶⁴CuCl₂. This was corroborated by the observation that ⁶⁴CuCl₂ was more cytotoxic in PCa cells than in non-tumoral cells. Overall, we showed for the first time that PCa cells had a higher sensitivity to ⁶⁴CuCl₂ than healthy cells, supporting the idea that this compound deserved to be further evaluated as a theranostic agent in PCa.

A Comprehensive Safety Evaluation of 68Ga-Labeled Ligand Prostate-Specific Membrane Antigen 11 PET/CT in Prostate Cancer: The Results of 2 Prospective, Multicenter Trials

PURPOSE

The aim of this study was to evaluate the clinical safety profile of the Ga-PSMA-11 ligand for PET/CT imaging in prospective clinical trials.

METHODS

Eighty-eight patients with newly diagnosed or recurrent prostate cancer participated in 2 prospective trials. Safety reporting was identical in the 2 trials. The Ga-PSMA-11 ligand was administered as 2 MBq/kg body weight (mean, 9.2 μg, 9.7 nmol). The reporting of clinical adverse events (AEs) and the measurement of blood pressure (BP) and heart rate (HR) were performed prior to injection (baseline); immediately after injection of Ga-PSMA-11 (postinjection); at 1, 10, and 60 minutes after injection; and after acquisition of the PET/CT scan (postscan). All hemodynamic assessments were performed in the supine position, except for the postscan measurement (sitting). The patients were interviewed regarding any AEs at baseline, postinjection, or postscan. In addition, the patients were instructed to report any AEs during the investigation and to contact the investigator if AEs occurred during the rest of the day. Adverse events were classified as mild, moderate, or severe by the patients and categorized by the investigator using the CTCAE (Common Terminology Criteria for Adverse Events) version 4.0.

RESULTS

There were no reported clinical AEs. There were significant decreases in systolic BP (P < 0.001) and HR (P < 0.001) over time. In comparison, the diastolic BP increased significantly (P < 0.001). After removal of the last observation (supine position), there was no time-dependent change in systolic or diastolic BP, but the significant change in HR remained. The mean changes over the entire observation period were minimal (systolic BP, -6 to 5 mm Hg; diastolic BP, -2 to 3 mm Hg; HR, decrease of 5 beats/min). No patients developed hypotension. Fifty-five patients presented with hypertension at baseline, which increased by 1 CTCAE grade in 15 patients and by 2 grades in 2 patients. A large number of cases of asymptomatic (grade 1) bradycardia were observed, primarily in patients with preexisting bradycardia. One patient developed transient grade 1 tachycardia. No patients required medical intervention for cardiovascular perturbations.

CONCLUSIONS

Ga-PSMA-11 PET/CT was very well tolerated. We consider Ga-PSMA-11 to be safe for human application.

The standards of an ultrasound examination of the prostate gland. Part 2

The paper discusses the rules of the proper performing of the ultrasound examination of the prostate gland. It has been divided into two parts: the general part and the detailed part. The first part presents the necessary requirements related to the ultrasound equipment needed for performing transabdominal and transrectal examinations of the prostate gland. The second part presents the application of the ultrasound examination in benign prostatic hyperplasia, in cases of prostate inflammation and in prostate cancer. Ultrasound examinations applied in the diagnostics of benign prostatic hyperplasia accelerated the diagnosis, facilitated the qualification to surgery and the selection of the treatment method. The assessment of the size of the prostate gland performed using the endorectal ultrasound examination is helpful in making the choice between transurethral electroresection and adenomectomy. In prostate inflammation this examination should be performed with particular gentleness due to pain ailments. The indication for performing the examination in acute inflammation is the suspicion of prostate abscess. In chronic, exacerbating prostatitis it is possible to perform an intraprostatic antibiotic injection. In the recent years increased morbidity and detectability of prostate gland cancer is observed among men. In Poland it ranks second (13%) among diseases occurring in men. The indication for an endorectal examination is the necessity to assess the size of the prostate gland, its configuration, the echostructure in classical ultrasonography, the vascularization in an ultrasound examination performed with power doppler and, if possible, the differences in the gland tissue firmness (consistency) in elastography. The ultrasound examination is used for performing the mapping biopsy of the prostate gland - from routine, strictly defined locations, the targeted biopsy - from locations suspected of neoplastic proliferation and the staging biopsy - from the neurovascular bundles, the seminal vesicles, from the apex of the prostate and from the periprostatic tissue - this type of biopsy is supposed to help in determining local staging of the neoplastic disease. The ultrasound examination is also helpful during the treatment of the neoplasm performed using brachytherapy or using the method of ultrasonic ablation which is still in the phase of clinical trials.

PSMA PET and Radionuclide Therapy in Prostate Cancer

Prostate cancer (PCa) is the most common malignancy in men and a major cause of cancer death. Accurate imaging plays an important role in diagnosis, staging, restaging, detection of biochemical recurrence, and for therapy of patients with PCa. Because no effective treatment is available for advanced PCa, there is an urgent need to develop new and more effective therapeutic strategies. To optimize treatment outcome, especially in high-risk patients with PCa, therapy for PCa is moving rapidly toward personalization. Medical imaging, including positron emission tomography (PET)/computed tomography (CT), plays an important role in personalized medicine in oncology. In the recent years, much focus has been on prostate-specific membrane antigen (PSMA) as a promising target for imaging and therapy with radionuclides, as it is upregulated in most PCa. In the prostate, one potential role for PSMA PET imaging is to help guide focal therapy. Several studies have shown great potential of PSMA PET/CT for initial staging, lymph node staging, and detection of recurrence of PCa, even at very low prostate-specific antigen values after primary therapy. Furthermore, studies have shown that PSMA PET/CT has a higher detection rate than choline PET/CT. Radiolabeled PSMA ligands for therapy show promise in several studies with metastatic PCa and is an area of active investigation. The "image and treat" strategy, with radiolabeled PSMA ligands, has the potential to improve the treatment outcome of patients with PCa and is paving the way for precision medicine in PCa. The aim of this review is to give an overview of recent advancement in PSMA PET and radionuclide therapy for PCa.

A Review of Imaging Methods for Prostate Cancer Detection

Imaging is playing an increasingly important role in the detection of prostate cancer (PCa). This review summarizes the key imaging modalities-multiparametric ultrasound (US), multiparametric magnetic resonance imaging (MRI), MRI-US fusion imaging, and positron emission tomography (PET) imaging-used in the diagnosis and localization of PCa. Emphasis is laid on the biological and functional characteristics of tumors that rationalize the use of a specific imaging technique. Changes to anatomical architecture of tissue can be detected by anatomical grayscale US and T2-weighted MRI. Tumors are known to progress through angiogenesis-a fact exploited by Doppler and contrast-enhanced US and dynamic contrast-enhanced MRI. The increased cellular density of tumors is targeted by elastography and diffusion-weighted MRI. PET imaging employs several different radionuclides to target the metabolic and cellular activities during tumor growth. Results from studies using these various imaging techniques are discussed and compared.