MRI-ultrasound combination could improve cancer diagnosis

Doctors in the US are hoping to improve prostate cancer diagnosis by combining MRI with real-time 3D ultrasound for tissue sample collection.

The new technique, developed at the University of California Los Angeles (UCLA), allows for more targeted prostate biopsy and could reduce the number of samples doctors need to take to diagnose the cancer.

The fusion of the two technologies provides a major improvement on the current methods that were originally devised in the mid-1980s, according to UCLA’s Dr Leonard S Marks.

‘It’s difficult to identify and target suspicious areas using two-dimensional, conventional ultrasound, so urologists currently take samples systematically from the entire prostate,’ said Marks.

Many small prostate cancers are not serious health threats, and the new imaging technology could help doctors to differentiate the serious cancers from the insignificant, which often do not require surgery.

The technology could be particularly beneficial for patients who had prior negative biopsies but had other medical indicators of a prostate problem, and for those with low-risk cancers that need monitoring over time.

Four UCLA departments — urology, radiology, pathology and biomedical engineering — collaborated with medical device company Eigen to develop and test the technology and conducted a study recently outlined in the journal Urologic Oncology.

‘While other major cancers can be imaged within the organ of origin, the small, compact prostate has proven elusive for a number of reasons, such as the similarity of cancer and benign tissue and the lack of tissue uniformity,’ said study co-author Dr Daniel Margolis.

‘We hope the multi-parameter MRI information, used with the new system, will help us better distinguish problem areas and provide the most accurate information possible.’

He added that the additional MRI information might help to improve targeting and possibly eliminate the need for taking multiple biopsy samples. Currently, 12 areas from the entire prostate are systematically biopsied, whether they are suspicious areas or not.

The initial MRI scan is used to detect suspicious contrasts in tissue, abnormal cellular density and unusual blood flow within the prostate. Specialist software then generates a 3D image of the prostate showing the location of any suspicious areas.

During the biopsy itself, the MRI images are fused with the real-time ultrasound, providing a 3D visualisation that is used to guide the tiny biopsy needle into targeted areas.

‘The application of such three-dimensional imaging or modelling is used in other fields, such as animation and gaming, and is also being used more frequently in developing medical diagnostics,’ said UCLA biomedical engineer Shyam Natarajan.

The UCLA team found that targeted biopsy was about five times more likely to find cancer than non-targeted, systematic biopsy. Re-biopsy of a suspicious site was found to be accurate within a few millimetres.

The team is also helping to track the accuracy of MRI-ultrasound fusion by studying cancerous prostates that have been removed from study patients. The researchers can then compare the location of the diseased tissue on the actual prostate with the MRI and ultrasound fusion scans.