Contrast enhanced transrectal ultrasound of the prostate An experimental and clinical study

Abstract: The purpose of this thesis was to evaluate the diagnostic potential of a new ultrasound contrast agent,SonazoidTM, intended for use in patients with suspicion of prostate cancer.The sonographic appearance of normal prostatic vascularity in dogs was evaluated before and after injection of Sonazoid,using different Doppler flow detection modes.The use of Sonazoid significantly improved the visibility of the vascular pattern in normal dog prostate,both with colour and power Doppler imaging.There was a significant difference in the depiction of blood flow in the prostate between the two imaging modalities,showing the power Doppler superior to colour Doppler imaging.The contrast revealed a radial,spoke-like intraprostatic pattern,not seen prior to contrast injection.Different ultrasound imaging modalities were tested in a small group of young healthy male volunteers to evaluate the visibility of the normal prostate blood flow with and without Sonazoid.The ultrasound contrast agent improved the visibility of the normal human prostate vascular anatomy for both colour and power Doppler imaging.Again,the improvement was significantly better for power Doppler than for colour Doppler imaging.Using fundamental B-mode,there was no major difference in the ultrasound appearance of the prost ate vascular it y before and after i njection of Sonazoid.Cont rast dynamic st udies of blood flow wit hi n t he normal gland showed a filling from the periphery towards the centre in all subjects,demonstrating a symmetric, radial vascular pattern.A canine prostate model was used to investigate if Sonazoid,could improve the visualisation of prostatic vessels to better delineate areas on normal and decreased blood flow.Both 2D and 3D power Doppler imaging was performed in this study.The visibility of the prostate blood flow improved significantly following injection of Sonazoid for both 2D and 3D power Doppler imaging.There was,however,no major difference in depicting the vascularity using 2D and 3D imaging.After injection of Sonazoid,a disturbance of the radial vascular pattern and a lack of blood flow symmetry between the two prostate lobes were possible to identify.The added information gained by injection of Sonazoid made it possible to identify areas of decreased blood flow not seen prior to contrast injection.The vascular pattern of lesions,identified with B-mode imaging in patients with suspicion of prostate cancer,was studied,using Sonazoid.Contrast dynamic inflow in the lesions,compared to the adjacent tissue was investigated in the same study.Prostate cancer lesions appeared hypervasuclar prior to ultrasound contrast agent.Three of six cancer lesions changed from hypervascular to marked hypervascular following injection of Sonazoid,a finding that might be interpreted as a higher level of confidence.None of the non-cancer lesions were assessed as hypervascular after Sonazoid injection,a possible increased value of a negative finding.Four of the cancer lesions enhanced earlier compared to the surrounding prostate tissue,following ultrasound contrast injection.The results indicate that changes in vascular architecture,e.g.induction of angiogenesis by tumour cells,can be observed by ultrasonographically determining the inflow pattern of an intravenously injected ultrasound contrast agent.