Inclusion Criteria:

- Men aged 40 - 80 years old

- Biopsy proven intermediate/high risk clinically localized prostate cancer, as
determined by a Gleason score of 7 or higher, clinical stage T2b or higher, or PSA >
10. Pathology will be confirmed by at least two reviews

- Patients opting for EBRT (external beam radiation therapy, standard of care) without
hormonal ablation

- Ability to undergo serial TRUS procedures

- Ability to give informed consent

Exclusion Criteria:

- Subject has known hypersensitivity to octafluoropropane.

- Evidence of distant metastatic disease on staging evaluation

- Previous treatment for prostate cancer, including any form of androgen ablation

- Previous procedures involving the anus or rectum, making serial TRUS difficult or
dangerous

- Expected life expectancy less than 10 years

- Baseline testosterone < 200 ng/dL

- Subject with cardiac shunts and elevated pulmonary hypertension

- Subject has worsening or clinically unstable congestive heart failure.

- Subject has acute myocardial infarction or acute coronary syndrome.

- Subject has ventricular arrhythmias or is high risk for arrhythmias.

- Subject has respiratory failure, severe emphysema or pulmonary emboli.

- Subject has a history of cardiac shunt or pulmonary hypertension.