Accuracy of Lymph Node Imaging in Prostate Cancer: PSMA PET-CT and Nano-MRI

Accuracy of Lymph Node Imaging in Prostate Cancer: A Prospective Cohort Study to Determine the Concordance Between Two Imaging Modalities, "Combidex" Magnetic Resonance Imaging (Nano MRI) and 68Ga-PSMA Positron Emission Tomography (PET)

Following curative intended therapy in prostate cancer patients, a high proportion of patients (approx. 25%) relapse with local and/or distant recurrence. The metastasis of a lymph node (LN) in a patient with prostate cancer means that the disease has become systemic with the increased risk of disease progression. Therefore the ability to detect the presence of LN metastasis is important in terms of disease prognosis and treatment options. In the past, patients with LN metastasis have had poor prognoses due to the scarcity of accurate staging techniques and toxic treatment regimens such as radiotherapy. For those patients with a medium to high risk of having LN metastasis, the current procedure is a bilateral pelvic lymph node dissection (PLND). This is the standard procedure prior to curative treatment with either radical prostatectomy or radiation therapy. However, the procedure is not optimal due to the frequent inability to remove all positive lymph nodes within the dissection area. 41% of metastatic LN disease is not found, due to these LN being outside the routine surgery field. As a result, some urologists will perform an extended lymphadenectomy (e-PLND), which leads to extended operating times and the risk of complications. Also, therapy of LN metastases has limitations: more than 50% of metastatic LN are outside the routine (RTOG-CTV) radiation field. Thus the effect of standard LN radiotherapy is limited. Currently used imaging techniques such as CT and conventional MRI are also not sensitive enough to detect prostate cancer metastases due to the small size of the nodes (< 8mm).

In this study, patients that undergo a pelvic lymph node dissection will be undergoing a 68Ga PSMA PET-CT and a nano-MRI prior to surgery. The results of the PSMA PET-CT and the nano-MRI will be validated using the pathology results of the (PLND).

Inclusion Criteria:

• Male, aged 18 years Prostate cancer present (Gleason ≥ 7) and/or
• PSA ≥ 15 and/or
• Clinical or radiological Stage T3
• Subject will be undergoing a pelvic lymph node dissection as part of the prostate cancer treatment.
• Subject is willing to sign and date the study Informed Consent form
• Signed, written informed consent

Exclusion Criteria:

• Patients who cannot lie still for at least 30 minutes or comply with imaging
• Subject has medical conditions that would limit study participation (per physician discretion)
• Subject has hemochromatosis and liver disease
• Subject has known allergy against Fe-products or dextranes
• Subject is enrolled in one or more concurrent studies that would confound the study results of this study as determined by the study investigators
• Previous treatment for prostate cancer (surgery, radiotherapy, chemotherapy, hormone androgen deprivation therapy)
• Proven bony metastatic disease, visceral metastases or lymph node metastases above the level of the aortic bifurcation
• Patients who will not get prostatectomy or pelvic lymph node dissection for any reason
• Patient has absolute contra-indications to undergoing MRI scanning