Gallium 68 PET/MRI may detect prostate cancer better than multiparametric MRI

Researchers from the University of California, San Fransisco (UCSF) have demonstrated that gallium 68–labeled prostate-specific membrane antigen–11 PET/MRI may detect higher rates of prostate than multiparametric MRI, according to a study published online Sept. 18 in Radiology.  

The research details how Robert Hicks, MD, from the department of radiology and biomedical imaging at UCSF, and colleagues found that prostate-specific membrane antigen PET could be used to characterize cancer and determine malignancy within a single exam.  

“Our findings may improve the diagnostic confidence of radiologists when evaluating patients referred for imaging after a positive biopsy result,” Hicks et al. wrote. “Radiologists will then be able to risk-stratify patients as having a high likelihood of clinically significant prostate cancer and identify appropriate candidates for definitive therapy.”  

The study included 32 men with prostate cancer who underwent 68Ga-PSMA-11 PET/MRI exams before undergoing a radical prostatectomy between December 2015 and June 2017. Board certified radiologists were blinded to the exam results, according to the researchers.  

Tumor localization was based on 30 anatomic regions. Specifically, region-specific sensitivity and specificity were calculated for both were calculated for PET/MRI and multiparametric MRI by using raw stringent and alternative neighboring approaches.  

Study results included the following:  

  • Region-specific sensitivities of PET/MRI and multiparametric MRI were 74 percent and 50 percent, with the alternative neighboring approach and 73 percent and 69 percent, respectively, with the population-averaged generalized estimating equation.  
  • Region-specific specificity of PET/MRI was similar to multiparametric MRI with the alternative neighboring approach versus 90 percent and in population-averaged estimates versus 70 percent.  
  • Measurements of tumor maximum standardized uptake value were predictive of histopathologic tumor patterns, with values greater than 6.9 suggestive of overall tumor Gleason pattern of at least 7.  

“Our data obtained with both the raw stringent and neighboring approaches support the observation that 68Ga-PSMA-11 PET/ MRI aids in the diagnosis of prostate cancer compared with imaging with multiparametric MRI,” the researchers wrote. “The results of logistic regression analysis may provide insight into tumor biology.”