MRI / Ultrasound Fusion With Contrast-Enhanced Ultrasound Guidance

Overview

Prostate cancer is the most common cancer in men. It is most often detected by an abnormal digital rectal exam or an elevated Prostate-Specific Antigen -determine by a blood test. When it is suspected that someone may have prostate cancer, a biopsy is ordered. This biopsy is performed by the Radiologist with ultrasound guidance through the rectum. In some patients, a Magnetic Resonance Imaging (MRI) scan of the prostate may be ordered to further evaluate the prostate. In some situations, the MRI and Ultrasound images will be fused (digitally merged) together during the ultrasound procedure to help localize the questionable lesions. Recent research has used an additional component known as a contrast agent - an intravenously injected inert substance - which is identifiable by ultrasound. This inert substance is more obvious in areas of increased blood flow, which is a common finding in cancerous lesions. In this research project, we would like to determine whether the use of contrast-enhanced ultrasound is beneficial in improving accuracy of the biopsies taken and the relative correlation to the MRI/ Ultrasound-fused images.

It is the hypothesis that cancerous lesions in the prostate will have an increased amount of blood flow, and that the lesions identified under ultrasound with the benefits of contrast-enhanced imaging can be correlated to the MRI Findings in real-time. A study of 50 patients who would be undergoing MRI/Ultrasound fusion would be selected to have contrast added to their procedure. The lesions identified on MRI would then be evaluated with contrast-enhanced ultrasound. The findings from the contrast study could then be correlated with the MRI findings. The rest of the prostate gland would also be assessed using the contrast agent for lesions not identified on the MRI imaging study. The pathology results could be correlated with both the contrast study and the MRI study both independently, and in conjunction with the two imaging modalities. If a correlation between highly suspicious lesions on the MRI and significant flow patterns under contrast can be established, then the sensitivity and specificity of contrast-enhanced ultrasound can be increased. While MRI / Ultrasound Fusion is being shown to increase prostate cancer identification and targeting for biopsy, it is a very limited modality due to the costs associated. Many sites will also not have access to an MRI unit, and the fusion system is prohibitively expensive, and requires specialized training to configure the system and modulate the images in real-time. However, ultrasound is an in expensive modality that is readily available. If the materials and methods in the utilization of contrast-enhanced ultrasounds can be correlated to MRI / Ultrasound fusion, better protocols can be developed for contrast-enhanced ultrasound. This more cost-effective method of identifying and targeting prostate cancer could then be exported to smaller communities who would otherwise still be carrying out the sextant biopsy model.