Endorectal Coil Magnetic Resonance Imaging Research Articles

PROSPECTIVE EVALUATION OF ENDORECTAL MAGNETIC RESONANCE IMAGING TO DETECT TUMOR FOCI IN MEN WITH PRIOR NEGATIVE PROSTASTIC BIOPSY: A PILOT STUDY

ABSTRACTPurpose: Prostate cancer foci have a characteristic appearance on endorectal magnetic resonance imaging (MRI) which might be useful for prostate cancer detection. In this pilot study the ability of endorectal MRI to detect prostate cancer foci prospectively in men at risk for a malignant prostatic neoplasm is assessed.Materials and Methods: Endorectal MRI was performed in 33 consecutive men with 1 or more prior negative prostatic biopsies. All studies were read by 2 MRI dedicated study radiologists in consensus before and after receiving patient clinical data. Areas of interest on endorectal MRI were mapped as low, moderate or high suspicion for carcinoma on a prostate model. Directed needle biopsy cores of the prostate were obtained based on this model, and the histopathological findings were compared with MRI results.Results: Carcinoma was detected in 7 of 33 men (21.2%) on post-MRI biopsy, including 1 of 18 (5.6%) with low, 1 of 8 (12.5%) with moderate and 5 of 7 (71.4%) with high suspicion MRI...

Estimation of prostate cancer volume by endorectal coil magnetic resonance imaging versus. pathologic volume

Estimation of prostate cancer volume by endorectal coil magnetic resonance imaging versus. pathologic volume

Endorectal coil MR imaging findings in hemospermia.

The purpose of this study was to illustrate the spectrum of abnormalities found at endorectal coil magnetic resonance (MR) imaging in patients with hemospermia. Ninety patients aged between 23 and 71 years (mean age 41 years) presenting with hemospermia underwent evaluation with endorectal coil MR imaging at 1.5 T. Duration of hemospermia ranged between 5 days and 4 years (mean 15 months). MR examination protocol included T1-weighted spin-echo (SE) and T2-weighted fast SE MR images obtained in the sagittal, coronal, and axial planes. Abnormalities were observed on endorectal-coil MR images in 49 of 90 patients (54%). Blood within the seminal vesicle or the ejaculatory duct was recognized in 23 of 90 patients (25%). Dilatation of the seminal vesicles or the ejaculatory duct was observed in 31 of 90 patients (34%). Cystic lesions were identified in 14 cases, eight of which involved the utriculus and six the ejaculatory duct. Calculi within the seminal vesicles were depicted in seven patients. No malignant disease was demonstrated. In conclusion, despite the evidence that hemospermia is most often a benign and self-limiting condition, we found that endorectal coil MR imaging can detect abnormal findings in more than half of the patients, and may be helpful in assessing the level at which hemorrhage occurred and in defining the cause of the disease.

Endorectal coil MR imaging findings in hemospermia

Endorectal coil MR imaging findings in hemospermia

MAGNETIC RESONANCE IMAGING DETECTION OF SYMPTOMATIC NONCOMMUNICATING INTRAURETHRAL WALL DIVERTICULA IN WOMEN

Purpose We documented the merit of endorectal coil magnetic resonance imaging (MRI) for detecting intraurethral wall diverticula in women. Materials and Methods We report on 3 women with a long-standing history of urinary frequency, urgency and voiding dysfunction who had been treated unsuccessfully for other etiologies. Results MRI of the urethra revealed noncommunicating intraurethral wall diverticula, which were excised. Conclusions Urethral MRI should be considered in women with lower urinary tract symptoms secondary to a suspected urethral pathology.

Preoperative magnetic resonance staging of rectal cancer with an endorectal coil and dynamic gadolinium enhancement.

The aim of the study was to assess the value of endorectal coil magnetic resonance imaging (MRI) with gadolinium enhancement in the preoperative staging of rectal cancer. In addition to standard evaluation, patients with rectal lesions were assessed by MRI obtained with a pelvic phased-array coil in combination with an endorectal coil. The study group comprised 29 patients with rectal cancer staged with an endorectal coil who had surgery without preoperative adjuvant therapy. In addition to standard T1- and T2-weighted images, dynamic contrast-enhanced images were acquired in all patients. Considerable interobserver variation was noted, particularly for pathological tumour stage pT1 or pT2 (kappa = 0.36). Compared with pathological findings, endorectal MRI correctly staged nine patients, overstaged 16 and understaged four. Whilst lymph node metastases were accurately detected in 70 per cent of patients, the positive predictive value was only 58 per cent. MR staging of rectal cancer with an endorectal coil and gadolinium enhancement is inaccurate for early tumours (stage T1 or T2) and is associated with a considerable degree of interobserver variation for individual scan sequences.

Estimation of Prostate Cancer Volume by Endorectal Coil Magnetic Resonance Imaging vs. Pathologic Volume

Objective: Since tumor volume is recognized as an important predictor of clinical stage and disease outcome of prostate cancer, accurate preoperative estimation of tumor volume can play an important role in planning the appropriate treatment and establishing a patient’s prognosis. We performed this study to evaluate the accuracy of the endorectal coil magnetic resonance (MR) technique for reliable prediction of tumor volume in patients with prostatic cancer. Material and Methods: Endorectal coil MR imaging was performed in 57 consecutive men who were suspected to have prostate cancer. Subsequent ultrasound-guided transrectal biopsy revealed prostate cancer in 44 cases. The pathological volume of the surgical specimens of 25 selected patients who underwent radical prostatectomy was retrospectively compared to the volume estimated by endorectal coil MR studies, and the Pearson correlation coefficient was calculated. Results: In 15 patients the estimated size of the tumor was within 15% of the true tumor volume; in the remaining 10 cases MR imaging tended to underestimate large tumors and overestimate small ones. A significant correlation between the volumes as determined with MR imaging and measurements of surgical specimens was observed (r 0.94; slope 0.82). To our knowledge, this is the best correlation found between pathological volume and tumor volume as evaluated by any other imaging modality. Conclusions: Endorectal coil MR imaging is a powerful means of evaluating the prostate gland; however, further improvements in imaging and/or volume calculation are required to provide a more accurate preoperative assessment of prostate cancer volume.

Endorectal MRI of Prostate Cancer: Comparison with Findings on Radical Prostatectomy

Purpose : To assess the accuracy of magnetic resonance (MR) imaging using an endorectal surface coil ineval-uation of local lesions of prostate carcinoma. Materials and Methods : Twenty patients with surgically provenprostate carcinoma underwent MR imaging using a 1.5T unit and an endorectal surface coil made at the Asan MedicalCenter. T1-weighted images in the axial plane and T2-weighted images in the axial, coronal, and sagittal planeswere obtained in all patients. We divided the prostate gland into right and left lobe, then determined thelocation of carcinoma within it, as well as capsular penetration and seminal vesicle invasion. MR images werecompared with surgical specimens. Results : MR imaging using an endorectal surface coil accurately demonstratedthe staging of prostate carcino-ma in 60% of patients (12/20), but with regard to the location of carcinoma withinthe prostate gland, capsular penetration, and seminal vesicle invasion, only nine cases (45%) showed completeagreement between en-dorectal surface coil MR images and pathologic findings. The accuracy of localizing thecarcinoma within the prostate gland, capsular penetration, and seminal vesicle invasion were 65%(13/20),70%(14/20), and 90%(18/20), respectively. Conclusion : MR imaging using an endorectal surface coil for thelocalization of prostate carcinoma and periprostatic tissue invasion showed a low degree of accuracy. Morespecific imaging findings are therefore needed.

Magnetic resonance imaging of prostate cancer: Comparison of image quality using endorectal and pelvic phased array coils

To compare endorectal coil (ERC) and pelvic phased array (PPA) coil magnetic resonance imaging for delineation of the prostate gland and seminal vesicles. To compare ERC images at different inflation volumes of the ERC air balloon. Twenty-one patients underwent T2-weighted examinations using PPA and ERC. The ERC evaluations were performed at three balloon inflation volumes (60, 100 and 140 ml). All patients had proven prostate cancer. Images were analysed for visibility of anatomic structures, gland distortion, tumour visualization, artefacts (coil flare, coil-related artefact and rectal movement) and overall image quality. A grading system was used for each parameter. ERC assessments at increasing balloon inflations showed equivalent anatomical detail and overall image quality. However, increasing gland distortion and decreasing coil related flare was found with higher air inflations (P = 0.13 and P = 0.006, respectively). When compared with ERC images, visibility of the anterior gland and neurovascular bundles was better with the PPA coil (P = 0.0001 and 0.002, respectively). The overall image quality was superior with the PPA coil (P = 0.0001). However, no significant difference in visualization of tumour or delineation of tumour extent was observed between the two techniques. PPA imaging of the prostate gland provides images of superior quality compared with the ERC. This is mainly due to fewer artefacts with the PPA coil and improved anterior gland visibility. When ERC is used, air inflation to at least 100 ml reduces coil flare artefact.

NOVEL STAGING TOOL FOR LOCALIZED PROSTATE CANCER: A PILOT STUDY USING GENETIC ADAPTIVE NEURAL NETWORKS

An estimated $1.5 billion is spent annually for direct medical expenses and an additional $2.5 billion for indirect costs for the management of prostate cancer. Today there are several procedures for staging prostate cancer, including lymph node dissection. Despite these procedures, the accuracy of predicting extracapsular disease remains low (range 37 to 63, mean 45%). Use of multiple staging procedures adds significantly to the costs of managing prostate cancer. Recently artificial intelligence based neural networks have become available for medical applications. Unlike traditional statistical methods, these networks do not assume linearity or homogeneity of variance and, thus, they are more accurate for clinical data. We applied this concept to staging localized prostate cancer and devised an algorithm that can be used for prostate cancer staging. Our study comprised 1,200 men with clinically organ confined prostate cancer who underwent preoperative staging using serum prostate specific antigen, systematic biopsy and Gleason scoring before radical prostatectomy and lymphadenectomy. The performance of the neural network was validated for a subset of patients and network predictions were compared with actual pathological stage. Mean patient age was 62.9 years, mean serum prostate specific antigen 8.1 ng./ml. and mean biopsy Gleason 6. Of the patients 55% had organ confined disease, 27% positive margins, 8% seminal vesicle involvement and 7% lymph node disease. Of margin positive patients 30% also had seminal vesicle involvement, while of seminal vesicle positive patients 50% also had positive margins. The sensitivity of the network was 81 to 100%, and specificity was 72 to 75% for various predictions of margin, seminal vesicle and lymph node involvement. The negative predictive values tended to be relatively high for all 3 features (range 92 to 100%). The neural network missed only 8% of patients with margin positive disease, and 2% with lymph node and 0% with seminal vesicle involvement. Our study suggests that neural networks may be useful as an initial staging tool for detection of extracapsular extension in patients with clinically organ confined prostate cancer. These networks preclude unnecessary staging tests for 63% of patients with clinically organ confined prostate cancer.

Endorectal coil magnetic resonance imaging identifies locally advanced prostate cancer in select patients with clinically localized disease

Objectives. Endorectal coil magnetic resonance imaging (erMRI) has been reported to improve the prediction of pathologic Stage T3 disease in patients with clinical Stage T1,2 disease, prostate-specific antigen (PSA) of 10 to 20 ng/mL, biopsy Gleason score of 7 or less, and at least 50% of the biopsy specimens positive from a sextant sampling. This study examines the performance characteristics of the erMRI to predict established extracapsular extension (ECE), seminal vesicle invasion (SVI), and PSA failure-free survival (bNED) in this subgroup. Methods. The sensitivity, specificity, positive and negative predictive value, and accuracy of the erMRI to predict established ECE and SVI were calculated in the proposed subgroup. PSA failure-free survival stratified by the erMRI-defined stage was estimated by using the method of Kaplan and Meier. Results. The sensitivity, specificity, positive and negative predictive value, and accuracy to predict established ECE and SVI in clinical Stage T1, 2 patients was 65%, 100%, 100%, 79%, and 84%, respectively. No patient would have been excluded from surgery on the basis of a false-positive study. Moreover, the percent of patients with pathologic organ-confined disease would have increased from 32% to 61%, and the 3-year bNED rate would have increased from 12% to 45% ( P = 0.07) if only patients with erMRI Stage T2 disease were selected for surgery. Conclusions. The erMRI may significantly improve the identification of established ECE and SVI in select patients with prostate cancer preoperatively. Further study of the erMRI in these select patients is warranted and ongoing.

MAGNETIC RESONANCE IMAGING OF CLINICALLY LOCALIZED PROSTATIC CANCER

Purpose We assess the accuracy of endorectal coil magnetic resonance imaging (MRI) for detecting tumor localization, capsular penetration and seminal vesicle invasion in clinically organ confined prostate cancer. We also evaluate intra-observer and interobserver agreement in interpreting MRI studies. Materials and Methods MRI studies of 51 consecutive patients a mean of 61 years old with biopsy proved prostate cancer were retrospectively read twice by 2 radiologists in random order. Both radiologists marked tumor localization, capsular penetration and seminal vesicle invasion on standard tumor maps. These findings were compared with the histopathological results of radical prostatectomy specimens. Results The overall accuracy of detecting cancer localization was 61%. The detection rate for cancer foci less than 5 mm. was only 5% but for lesions greater than 10 mm. it was 89%. There was 91 and 80% accuracy for detecting capsular penetration and seminal vesicle invasion, respectively. Sensitivity and specificity were 60 and 63, 13 and 97, and 59 and 84% for localization, capsular penetration and seminal vesicle invasion, respectively. Intra-observer and interobserver agreement ranged from fair to good (kappa coefficient 0.240 to 0.647). Conclusions Endorectal MRI seems to be better than previously reported for detecting seminal vesicle invasion and tumor foci in the anterior half of the prostate. Sensitivity in detecting minor capsular penetration of the tumor was low, which can probably be improved by methodological development. MRI may be useful for locating cancer foci in patients with high prostate specific antigen values but repeatedly negative biopsy findings.

Assessment of prostate cancer volume using endorectal coil magnetic resonance imaging: a new predictor of tumor response to neoadjuvant androgen suppression therapy

Objectives. A clinical tool that can reliably assess prostate cancer response to androgen suppression is lacking. This pilot study was designed to identify the potential clinical factor(s) that correlate with tumor response after neoadjuvant therapy. Methods. Twenty-one patients managed with definitive local therapy and neoadjuvant androgen suppression (median 3 months [range 2 to 7]) between 1995 and 1997 comprise the study population. Fisher's exact test was used to test the significance of the proportion of patients with a given clinical factor and the outcome of pathologic organ-confined disease. The clinical factors tested included preoperative prostate-specific antigen, biopsy Gleason score, clinical stage, months of total androgen suppression, the change in the endorectal magnetic resonance imaging (erMRI)-defined stage, the change in erMRI-defined tumor, and the change in the erMRI-defined prostate volume during neoadjuvant androgen suppression. Results. All 21 patients had a decrease in the erMRI-determined prostate volume and prostate-specific antigen during androgen suppression, whereas only 10 of 21 (48%) had a reduction in the erMRI-determined tumor volume. There was a statistically significant increased proportion of patients with a decrease in the erMRI-determined tumor volume ( P = 0.008) who had pathologic organ-confined disease. Conclusions. The results of this pilot study suggest that the changes in the erMRI-determined tumor volume occurring during androgen suppression may be predictive of the tumor response. Validation in a larger prospective study is currently underway.

Prostate imaging may not be necessary in nonpalpable carcinoma of the prostate

Stage T1c carcinoma of the prostate is defined as a nonpalpable carcinoma (NPC-P) that is not visible by imaging and is identified by needle biopsy performed because of elevated prostate-specific antigen (PSA) concentrations. The purpose of this study was to define the incidence of normal findings on transrectal ultrasound (TRUS) and/or endorectal coil magnetic resonance imaging (EMRI) among patients with NPC-P, as well as to investigate the value of differentiating patients with Stage T1c disease from all other patients with NPC-P. The records of 2211 patients diagnosed with prostate carcinoma between 1988 and 1995 were reviewed to identify 291 men with NPC-P. TRUS and EMRI reports were analyzed with regard to the presence and laterality of hypoechoic nodules or low-signal areas reported on T2-weighted images, respectively. Ninety percent of patients (n = 262) had at least six prostate biopsies, 185 patients (64%) underwent both TRUS and EMRI, 224 (77%) had TRUS, and 251 (86%) had an EMRI study. Results were considered normal in 101 (47%) of 214 patients undergoing TRUS, in 58 (23%) of 249 undergoing EMRI, and in 22 (12%) of 185 undergoing both TRUS and EMRI. For the side of the prostate with positive biopsy results, correlation with imaging abnormalities was better for EMRI than for TRUS (39% versus 24%). There was no significant difference in mean PSA value, distribution of Gleason score, or unilateral versus bilateral positive biopsy results among patients with normal versus abnormal findings on both TRUS and EMRI. (1) Only 12% of men with NPC-P have no TRUS or EMRI abnormalities, fulfilling the criteria for Stage T1c prostate carcinoma. (2) Those patients with Stage T1c disease do not differ from patients with NPC-P up-staged by TRUS or EMRI, with regard to pretreatment PSA levels, Gleason scores, and the probability of having bilateral rather than unilateral positive biopsy results. (3) The value of classifying patients with NPC-P into Stage T1c versus higher stages of prostate carcinoma on the basis of imaging should be questioned.

Prediction of pathological tumor volume in clinically localized prostate cancer: value of endorectal coil magnetic resonance imaging.

The purpose of this study was to determine whether endorectal coil magnetic resonance imaging (MRI) enables accurate assessment of pathologic tumor volume in patients with clinically localized prostate carcinoma. Twenty-four patients with biopsy-proved prostate carcinoma underwent MRI at 0.5 T before radical prostatectomy. Tumor volumes were determined independently on axial fast-spin-echo (SE) T2-weighted MR images and whole-mount pathology slides of the surgical specimens. At pathology, tumor volumes ranged from 0.17 to 9.42 cm3 (mean +/- SD, 3.11 +/- 2.99 cm3). A strong correlation (r = .944) was found between measurements of tumor volume based on MR images and pathological specimens. The error was less than 0.5 cm3 in 14 cases, in the range of 0.5-1 cm3 in 7 cases, and more than 1 cm3 in 3 cases. By using an MR tumor volume of 2 cm3 as cutoff value, extracapsular tumor spread could be predicted with a sensitivity of 81.2%, a specificity of 100%, and an accuracy of 87.5%. Tumor volume determinations based on MR images seem to be accurate enough to be helpful in clinical decision-making.

Combined modality staging of prostate carcinoma and its utility in predicting pathologic stage and postoperative prostate specific antigen failure

Objectives This study was performed to predict the factors that can optimize preoperative staging for clinically localized prostate cancer patients. Methods Logistic and Cox regression multivariable analyses were performed on 480 surgically-managed prostate cancer patients to evaluate the ability of clinical stage, prostate specific antigen (PSA), biopsy Gleason sum, percent positive biopsies, and endorectal coil magnetic resonance imaging (erMRI) results to predict for pathologic established extracapsular extension (ECE), seminal vesicle invasion (SVI), and time to postoperative PSA failure. Results The characteristics of clinically organ-confined prostate cancer patients at high risk (>67%) for postoperative PSA failure within 3 years include: (A) PSA >20 ng/mL; (B) Biopsy Gleason sum ≥8; or (C) erMRI positive for extraprostatic disease and intermediate risk disease. For patients at intermediate risk (ie, either a PSA <4 and biopsy Gleason sum of 7; PSA >4 to 10 ng/mL and biopsy Gleason sum 5 to 7; or a PSA > 10 to 20 ng/mL and biopsy Gleason sum 2 to 7), despite 100% positive biopsies, 50% of patients had pathologic organ-confined disease. However, in the subset of intermediate-risk patients with a positive erMRI for either ECE or SVI and at least 50% positive biopsies, all had extraprostatic disease and failed biochemically by 47 months postoperatively. Intermediate-risk patients with <50% positive biopsies had pathologic organ-confined disease in at least 77% of the cases. Conclusions Combined modality staging using the PSA, biopsy Gleason sum, percent positive biopsies, and endorectal coil MRI findings in select patients can predict pathologic stage and postoperative PSA failure. Therefore, this combined modality staging may optimize patient selection for phase 3 trials examining the role of neoadjuvant androgen ablative therapy for patients with clinically localized disease.

Detection of extracapsular extension of prostate carcinoma with endorectal and phased-array coil MR imaging: multivariate feature analysis.

To determine which magnetic resonance (MR) imaging features are most predictive of extracapsular extension of prostate carcinoma. In 77 patients who had stage pT2 or pT3 prostate carcinoma, MR images were retrospectively reviewed by three readers with varying experience in interpretation of endorectal coil images of the prostate gland. MR imaging features assessed were broad tumor contact, smooth capsular bulge, irregular bulge, obliteration of the rectoprostatic angle, and asymmetry of the neurovascular bundle. Multivariate logistic regression analysis was performed to determine the relative value of each MR imaging feature. At multivariate analysis, obliteration of the rectoprostatic angle and asymmetry of the neurovascular bundle were most predictive of extracapsular extension, with a specificity of up to 95% and sensitivity of 38%. Poor-quality images reduced accuracy for all readers. The most experienced reader demonstrated overall accuracy of 77% in determination of extracapsular extension. Obliteration of the rectoprostatic angle and asymmetry of the neurovascular bundle were most indicative of extracapsular extension. Reader experience plays an important role in the ability to interpret prostate MR images and is an important contributor to interobserver variability.

Signal characteristics of tumors shown by high-resolution endorectal coil magnetic resonance imaging may predict outcome among patients with cervical carcinoma treated with irradiation: A preliminary study

The purpose of this study was to evaluate the role of high-resolution magnetic resonance imaging with the endorectal coil (eMRI) in the management of cervical carcinoma treated with definitive irradiation. Eighteen patients with invasive cervical carcinoma (International Federation of Gynecology and Obstetrics Stages Ib-IIIb) consented to evaluation with eMRI on a 1.5 tesla system with high resolution (400 x 400 microM). Images were read to provide staging information and to grade the signal characteristics of the individual tumors as low (dark), intermediate, or high (bright) relative to surrounding isointense fat. Patients were treated with standard megavoltage irradiation (prescribed dose, 80-85 Gray); shaped antero-posterior/postero-anterior or 4-field box techniques, plus brachytherapy, were used. In 39% of patients, tumors were determined to be in a higher stage by eMRI because of proximal vaginal involvement (n = 4) or the combination of proximal vaginal involvement and parametrial extension (n = 3). Features predictive of improved local control and survival without evidence of disease included stage, hemoglobin levels > or = 11, complete response to external irradiation, and bright signal characteristics. Compared with those who had dark and/or intermediate tumors, patients who had tumors with bright signal characteristics tended to present with earlier stage disease, were less likely to have anemia, and were more likely to have complete response to external irradiation. Prognostic information for clinical staging of cervical carcinoma was contributed by eMRI. The technique was more likely to suggest proximal vaginal involvement by a tumor than was examination under anesthesia. Signal characteristics of tumors may provide valuable predictive information that is supplementary to conventional discriminants of outcome that follow definitive irradiation. Such information could allow physicians to tailor treatment (e.g., by the addition of radiation sensitizers) at an earlier point in disease management.

Signal characteristics of tumors shown by high‐resolution endorectal coil magnetic resonance imaging may predict outcome among patients with cervical carcinoma treated with irradiation: A preliminary study

BACKGROUND. The purpose of this study was to evaluate the role of high-resolution magnetic resonance imaging with the endorectal coil (eMRI) in the management of cervical carcinoma treated with definitive irradiation. METHODS. Eighteen patients with invasive cervical carcinoma (International Federation of Gynecology and Obstetrics Stages Ib-IIIb) consented to evaluation with eMRI on a 1.5 tesla system with high resolution (400 x 400 μM). Images were read to provide staging information and to grade the signal characteristics of the individual tumors as low (dark), intermediate, or high (bright) relative to surrounding isointense fat. Patients were treated with standard megavoltage irradiation (prescribed dose, 80-85 Gray); shaped antero-posterior/postero-anterior or 4-field box techniques, plus brachytherapy, were used. RESULTS. In 39% of patients, tumors were determined to be in a higher stage by eMRI because of proximal vaginal involvement (n = 4) or the combination of proximal vaginal involvement and parametrial extension (n = 3). Features predictive of improved local control and survival without evidence of disease included stage, hemoglobin levels ≥ 11, complete response to external irradiation, and bright signal characteristics. Compared with those who had dark and/or intermediate tumors, patients who had tumors with bright signal characteristics tended to present with earlier stage disease, were less likely to have anemia, and were more likely to have complete response to external irradiation. CONCLUSIONS. Prognostic information for clinical staging of cervical carcinoma was contributed by eMRI. The technique was more likely to suggest proximal vaginal involvement by a tumor than was examination under anesthesia. Signal characteristics of tumors may provide valuable predictive information that is supplementary to conventional discriminants of outcome that follow definitive irradiation. Such information could allow physicians to tailor treatment (e.g., by the addition of radiation sensitizers) at an earlier point in disease management.

THE ROLE OF MR IMAGING IN THE SELECTION OF THERAPY FOR PROSTATE CANCER

Combined modality staging is a methodology in which all of the pretreatment clinical factors that are found to have independent prognostic significance on multivariable analysis for predicting a given outcome (e.g., pathologic stage) are used to determine the initial management. This method of staging provides an optimized assessment of the pathologic extent of local disease prior to management, and therefore is better able to define those patients in whom local only therapy is likely to be curative. Knowing more about the pathologic extent of disease prior to therapy provides a rationale for patient selection in clinical trials that test new management strategies against the current standards. The preoperative endorectal coil MR imaging study results have been shown on multivariable analysis (which included PSA, clinical stage, and biopsy Gleason score) to provide statistically independent prognostic information about the outcomes of pathologic stage, margin status, postoperative PSA failure, and the prediction of local only failure in the positive margin patient.