Carcinoma of the prostate gland: MR imaging with pelvic phased-array coils versus integrated endorectal--pelvic phased-array coils

Endorectal MRI using a 0.5 T mid-field system in the staging of localized prostate cancer

The accuracy of high field, endorectal MRI in the staging of localized prostate cancer has been the focus of many previous reports. We present our findings with a mid-field magnet. Twenty-two patients with clinically localized prostate cancer were prospectively staged with endorectal MRI using a 0.5 T magnet. All patients subsequently underwent radical prostatectomy and the results of pre-operative MRI staging were compared with the histological findings. The overall staging accuracy for mid-field, endorectal MRI was 77% (17/22). The sensitivity and specificity were 50% (7/14) and 100% (8/8), for diagnosing capsular penetration and 100% (4/4) and 94% (17/18), for seminal vesicle invasion. This study demonstrates that as a result of recent developments in mid-field MRI design it is now possible to use these MR systems in conjunction with an endorectal probe to stage localized prostate cancer and that the accuracy is comparable to previous reports using high-field magnets.

Breathhold imaging of the upper abdomen using a circular polarized-array coil: comparison with standard body coil imaging

Current studies emphasize the use of array coils to decrease noise and increase the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). We applied T1-weighted and T2-weighted standard nonbreathhold spin echo (SE) sequences and T1-weighted FLASH, TurboFLASH, T2-weighted spin-echo time (TSE), and heavily T2-weighted half Fourier acquisition single-shot TSE (HASTE) sequences during breathhold for abdominal imaging in 15 normal volunteers. The breathhold scans were performed using both a standard coil and a circular polarized array coil. We analyzed the signal intensity (SI), SNR, and CNR of abdominal organs in all sequences. SNRs increased in all cases by an overall factor of approximately 3 due to an 8% increase in overall SIs and a 50% decrease in noise when applying the array coil. Although the array-coil FLASH sequence performed at least as well as the respective SE sequence, the SNRs of the array-coil TurboFLASH, TSE breathhold, and HASTE sequences were generally lower. We conclude that array-coil imaging significantly improves fast imaging of the abdomen.

Prostate carcinoma patients upstaged by imaging and treated with irradiation. An outcome-based analysis

BACKGROUND

The American Joint Committee on Cancer (AJCC) staging of prostate cancer relies upon digital rectal examination (DRE) findings, but suggests using all available information, including prostate imaging studies, prior to definitive treatment of prostate carcinoma. We have studied whether patients upstaged by imaging have a different outcome after treatment with external beam radiation therapy (RT) from those not upstaged.

METHODS

The records of 499 men with clinically localized adenocarcinoma of the prostate treated with only definitive external beam irradiation from January 1986 to December 1993 were reviewed. The 348 patients with any one or a combination of the following pretreatment imaging studies were considered eligible; transrectal ultrasound (TRUS), pelvic MRI, or endorectal MRI. Patients were assigned two clinical stages: one based upon palpation criteria alone (palpation stage) and the other allowing for any upstaging by imaging abnormalities (AJCC or imaging stage). The Kaplan-Meier method was used to estimate biochemical no evidence of disease (bNED) survival where a failure was defined as a prostate specific antigen (PSA) greater than 1.5 and increasing. Differences in outcome were evaluated by the log-rank test.

RESULTS

Overall upstaging by TRUS or MRI to any higher stage occurred in 115 of 312 palpation T1c-T2c patients (37%). These upstaged patients had an unexpected improvement in bNED survival (84% vs. 71%, P = 0.05) compared with those who were not upstaged due to the upstaged patients having a significantly greater number with a pretreatment PSA < 10 ng/mL. T1c patients were upstaged by imaging in 81% of the 94 patients. The 36-month bNED survival of palpation T1c and imaging T2 patients was similar (88% vs. 88%, P = NS), but both were significantly improved compared with the 36-month bNED survival for palpation T2 patients (88% vs. 71%, P = 0.04). There was no significant difference in 36-month bNED survival for imaging T2c (bilobar disease) patients compared with their original palpation stage disease. Upstaging to T3 occurred in 10% of palpation T1c-T2c patients. There was no difference in 36-month bNED survival for the imaging T3 patients compared with their original palpation stage (84% vs. 71%, respectively, P = 0.04). There was a significant improvement in the 36-month bNED survival for imaging T3 patients compared with palpation T3 patients (84% vs. 50% respectively, P = 0.01). Multivariate analysis demonstrated palpation stage to be a significant predictor of bNED survival (P = 0.001), while AJCC stage (including imaging) is not predictive.

CONCLUSIONS

Using the endpoint of bNED survival, upstaging by TRUS/MRI does not separate prostate cancer patients treated with RT into groups with different prognoses. Upon multivariate analysis, palpation stage alone, not AJCC stage including imaging upstaging, is a significant predictor of bNED survival.