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Sources of Funding: National Institutes of Health, the Institute of Diabetes and Digestive and Kidney Diseases_x000D_ (NIH/NIDDK)_x000D_

Introduction

New protein toxin therapies directly injected into the prostate are in clinical trials for prostatic diseases. A major challenge is predictable control of distribution. Magnetic resonance imaging (MRI) can potentially provide useful insight into the movement of liquid agents within organs after injection. Our objectives are to evaluate the distribution of injected liquids as a function of prostate anatomy and physiology, and of device design

Methods

Injections of MRI contrast reagents were placed into 18 ex-vivo human prostates after surgical excision in standard of care therapy for invasive bladder cancer patients, with IRB approval. Contrast agents were infused into the specimens via standard hollow needles and needles with a porous customizable length, and their performances were compared. MRI images were acquired using sequences to quantify volume delivered, distribution, and backflow.

Results

MRI analysis revealed heterogeneous distribution of infusates in the specimens. Tracer distribution in the tissue was significantly higher in the porous needle [1480 ± 802 ul vs 624 ± 767 ul, p-value = 0.036]. The porous needle design demonstrated a 3-fold greater delivery of infusate into the ex vivo prostate, a 2-fold greater volume of distribution, and 2-fold greater fraction of infused distribution compared to standard needle. The volume of distribution divided by the amount infused (Vd/Vi) increased by 80% with the porous needle, though no statistically significant association due to small sample size.

Conclusions

This study demonstrated that prostatic tissue is anatomically heterogeneic, which presents considerable challenge to achieving a desired distribution, particularly from a standard needle. Use of a porous needle provides improved distribution over the standard needle. MRI demonstrated infusate distribution and obstacles, and may be of value in pre-injection therapy planning.

Funding

National Institutes of Health, the Institute of Diabetes and Digestive and Kidney Diseases_x000D_ (NIH/NIDDK)_x000D_