Radiology: Multiparametric 3T MRI useful for prostate cancer detection
Multiparametric 3T MRI for detection of prostate cancer by using T2 weighted MRI, MR spectroscopy and dynamic contrast-enhanced MRI can enable the detection of tumors with reasonable sensitivity and specificity values, said a study published in the March issue of Radiology.
Baris Turkbey, MD, of the division of cancer treatment and diagnosis at the National Institutes of Health in Bethesda, Md., and colleagues said that their HIPAA-compliant study determined that the combined use of anatomic and functional MR techniques improves the overall performance of MR imaging for prostate tumor detection.
The researchers recruited 70 consecutive patients with an average age of 60.4 years for their single-site, prospective study between June 1, 2004 and Dec. 31, 2007. Each patient had biopsy-proved prostate cancer, with a median Gleason score of 7 and the average prostate-specific antigen level was 5.47 ng/mL for the included patient population.
After informed consent was obtained from each patient, images were obtained using a combination of six-channel cardiac and endorectal coils. The investigators independently evaluated MRI and pathologic findings in a blinded fashion, and then correlated with histopathologic findings by using side-by-side comparison, wrote the authors.
Analyses were conducted with a raw stringent approach and an alternative neighboring method, which accounted for surgical deformation, shrinkage and nonuniform slicing factors in pathologic specimens. Generalized estimating equations (GEEs) were used to estimate the predictive value of region-specific, pathologically determined cancer for all three modalities. The researchers said that this approach accounts for the correlation among multiple regions in the same individual.
The authors found that for T2-weighted MRI, sensitivity and specificity values obtained with the stringent approach were 0.42 and 0.83. For the alternative neighboring approach, sensitivity and specificity values were 0.73 and 0.89, said Turkbey and colleagues.
The combined diagnostic accuracy of T2-weighted MRI, dynamic contrast-enhanced MR imaging and MR spectroscopy for peripheral zone tumors was examined by calculating their predictive value with different combinations of T2-weighted MR imaging, dynamic contrast-enhanced MR imaging and MR spectroscopy, which provided significant independent and additive predictive value when GEEs were used, the authors noted.
Dynamic contrast-enhanced MR imaging and MR spectroscopy alone had lower sensitivity than did T2-weighted MRI, but they both presented a higher specificity than T2-weighted MR imaging, the researchers found. Moreover, they concluded that their addition to the MRI protocol increased the accuracy and predictive value of conventional T2-weighted MR imaging for accurately localizing peripheral zone cancers.
Tumors that were larger with higher Gleason scores, were found to be more easily detected by way of 3T MR imaging and combined T2-weighted MR, MR spectroscopy, and dynamic contrast-enhanced MR of the prostate at 3T can achieve a predictive value of 80 percent for prostate cancer detection, said the authors.
“Our data indicates that 3T endorectal MR imaging of the prostate accurately depicts low-moderate-risk prostate cancers in most cases,” said Turkbey. “The results for the combined diagnostic accuracy of T2-weighted MR imaging, dynamic contrast-enhanced MR imaging, and MR spectroscopy for PZ tumors on the basis of the GEEs with the raw stringent approach showed that combined use of anatomic (T2-weighted imaging) and functional (MR spectroscopy and dynamic contrast-enhanced MR imaging) modalities increases performance of MR imaging for tumor detection.”
Baris Turkbey, MD, of the division of cancer treatment and diagnosis at the National Institutes of Health in Bethesda, Md., and colleagues said that their HIPAA-compliant study determined that the combined use of anatomic and functional MR techniques improves the overall performance of MR imaging for prostate tumor detection.
The researchers recruited 70 consecutive patients with an average age of 60.4 years for their single-site, prospective study between June 1, 2004 and Dec. 31, 2007. Each patient had biopsy-proved prostate cancer, with a median Gleason score of 7 and the average prostate-specific antigen level was 5.47 ng/mL for the included patient population.
After informed consent was obtained from each patient, images were obtained using a combination of six-channel cardiac and endorectal coils. The investigators independently evaluated MRI and pathologic findings in a blinded fashion, and then correlated with histopathologic findings by using side-by-side comparison, wrote the authors.
Analyses were conducted with a raw stringent approach and an alternative neighboring method, which accounted for surgical deformation, shrinkage and nonuniform slicing factors in pathologic specimens. Generalized estimating equations (GEEs) were used to estimate the predictive value of region-specific, pathologically determined cancer for all three modalities. The researchers said that this approach accounts for the correlation among multiple regions in the same individual.
The authors found that for T2-weighted MRI, sensitivity and specificity values obtained with the stringent approach were 0.42 and 0.83. For the alternative neighboring approach, sensitivity and specificity values were 0.73 and 0.89, said Turkbey and colleagues.
The combined diagnostic accuracy of T2-weighted MRI, dynamic contrast-enhanced MR imaging and MR spectroscopy for peripheral zone tumors was examined by calculating their predictive value with different combinations of T2-weighted MR imaging, dynamic contrast-enhanced MR imaging and MR spectroscopy, which provided significant independent and additive predictive value when GEEs were used, the authors noted.
Dynamic contrast-enhanced MR imaging and MR spectroscopy alone had lower sensitivity than did T2-weighted MRI, but they both presented a higher specificity than T2-weighted MR imaging, the researchers found. Moreover, they concluded that their addition to the MRI protocol increased the accuracy and predictive value of conventional T2-weighted MR imaging for accurately localizing peripheral zone cancers.
Tumors that were larger with higher Gleason scores, were found to be more easily detected by way of 3T MR imaging and combined T2-weighted MR, MR spectroscopy, and dynamic contrast-enhanced MR of the prostate at 3T can achieve a predictive value of 80 percent for prostate cancer detection, said the authors.
“Our data indicates that 3T endorectal MR imaging of the prostate accurately depicts low-moderate-risk prostate cancers in most cases,” said Turkbey. “The results for the combined diagnostic accuracy of T2-weighted MR imaging, dynamic contrast-enhanced MR imaging, and MR spectroscopy for PZ tumors on the basis of the GEEs with the raw stringent approach showed that combined use of anatomic (T2-weighted imaging) and functional (MR spectroscopy and dynamic contrast-enhanced MR imaging) modalities increases performance of MR imaging for tumor detection.”