MR spectroscopy imaging is highly accurate for early detection of prostate cancer in asymptomatic patients, with 87% sensitivity and 93% specificity, according to new research from Spain. With MRSI, it is possible to measure concentrations of choline, creatine, and citrate in tissue. The metabolic ratio of choline and creatine to citrate (CC/Ci) is related to the presence of cancer.
Researchers at Clinica Girona in Catalonia conducted a prospective study of 51 patients with a prostate-specific antigen level between 4 ng/mL and 15 ng/mL. They performed endorectal MR imaging, 3D MRSI, and systematic sextant biopsies and then compared results.
In the study group, 23 patients had cancer. MRSI had a sensitivity of 87%, specificity of 93%, and accuracy of 90%, in comparison with 70%, 75%, and 72%, respectively, for MRI alone. Accuracy of total PSA was 67%, while free PSA accuracy was much higher at 82.5%.
The findings suggest that MRSI could help cut down on negative biopsy results, said Dr. Joan Vilanova, who presented results at the 2006 European Congress of Radiology.
"MRI with MRSI can select patients for biopsy, especially when combined with clinical information such as the PSA level," said Vilanova, medical director at Clinica Girona.
MRSI could be a useful guide to suspected lesions, Vilanova said.
This research is promising, but in practice it may be difficult to get such a high rate of sensitivity and specificity with MRSI, said Dr. Duke Bahn, chair of radiology and medical director of the Prostate Institute of America based at Community Memorial Hospital in Ventura, CA.
The technique is not standardized on various scanners, and interpretation is highly operator-dependent, he said. It may be difficult to find practitioners who can achieve the rates shown in the Spanish study.
In general, MR is not commonly done in the prostate, largely because reimbursement has been lacking until recent years, according to Bahn.
"The application got off to a slow start, but more prostate centers are now offering MR," Bahn said.
