3D ultrasound boosts prostate imaging

Controversial new data questioning prostate-specific antigen screening could lead to a surge in 3D ultrasound imaging until more accurate serum markers appear. Three-D has shown prominent gains in diagnosis, staging, and management of prostate cancer, according to recent studies.

Safe, more diagnostically accurate 3T MRI has been proposed as an alternative to uncomfortable standard MRI studies with endorectal coils. Three-D ultrasound offers a similarly safe and comfortable diagnostic alternative that is far more affordable, said coauthor Dr. Guido D. Parra, an ob/gyn physician at the Human Reproductive Institute in Barranquilla, Colombia.

Parra and colleagues, principal investigator Dr. Eduardo De Nubbila and Dr. Israel Díaz Yunez, enrolled 30 patients with suspected lesions from elevated PSA or abnormal digital rectal examination. They evaluated these patients with conventional and 3D ultrasound and compared outcomes against ultrasound-guided biopsy.

The investigators found 3D ultrasound allowed a better evaluation of the prostate's anatomy, the tumor's extension, and its surrounding structures. They presented their results at the 2005 meeting of the American Institute of Ultrasound in Medicine in June.

Biopsy results revealed that 10 of 30 cases (33.3%) were positive for adenocarcinoma. Six were detected by 2D ultrasound and eight by 3D. The ultrasound techniques yielded sensitivity and specificity values of 60% and 90%, and 80% and 90%, respectively. Three-D ultrasound provided more accurate definition of lesion margins and extension of local invasion and helped classify patients as stage II, III, and IV in two, four, and two cases, respectively.

Transrectal 2D ultrasound usually requires manipulating the probe to get the appropriate scanning angle, causing discomfort to the patient. Transrectal 3D ultrasound requires only a 90° scanning angle sweep. With its increased number of viewing perspectives, 3D ultrasound has proved to be a far less operator-dependent method, allowing sonologists to perform postprocessing analysis at a separate workstation. It could also enhance the sensitivity and staging power of ultrasound-guided biopsies, said Parra, the current president of the Colombian Society of Ultrasound in Medicine.

In a different study, researchers from the Center for Surgical Advancement at Florida Hospital in Celebration introduced a 3D-based transperineal mapping technique for ultrasound-guided biopsies of the prostate.

Principal investigator Dr. Gary Onik, director of surgical imaging at the CSA, and colleagues enrolled 59 patients who underwent the procedure. Researchers carried the transperineal biopsies at 5-mm intervals across the prostate's length using a brachytherapy grid and an automated biopsy gun under 3D ultrasound guidance. The technique found malignant lesions in 56% of cases previously diagnosed as negative. The 3D mapping biopsy also helped change management in more than 88% of patients.

Onik presented his findings at the 2005 Society of Interventional Radiology meeting.

Three-D ultrasound transperineal mapping biopsies provide superior information on the extent and grade of prostate cancer. The technique can significantly influence therapeutic decision making, Onik said.

For more information from the Diagnostic Imaging archives:

Cryoablation freezes prostate cancer treatment complications

3T boosts MR's ability to pinpoint prostate cancer

Three-D ultrasound evolves in interventional radiology

Radiation oncologists map prostate therapy