Endorectal MR imaging before salvage prostatectomy: tumor localization and staging

PURPOSE: To evaluate retrospectively the accuracy of endorectal magnetic resonance (MR) imaging for the depiction of tumor, extracapsular extension (ECE), and seminal vesicle invasion (SVI) before salvage prostatectomy in patients with locally recurrent prostate cancer after radiation therapy, by using pathologic analysis as the reference standard. MATERIALS AND METHODS: The Institutional Review Board granted exempt status for this HIPAA-compliant study, with a waiver of informed consent. Forty-five consecutive patients (age range, 43-76 years) were identified who underwent salvage radical prostatectomy for prostate cancer at Memorial Sloan-Kettering Cancer Center between December 1, 1998, and October 31, 2004, and who underwent endorectal MR imaging prior to surgery. Tumor localization and determination of local stage with MR imaging were performed independently by two radiologists. Interpretations were compared to pathologic findings from surgical specimens. Interrater variability was estimated with the kappa statistic. Areas under the receiver operating characteristic curve (AUCs) were used to assess the accuracy of endorectal MR imaging in tumor detection and determination of ECE and SVI. RESULTS: Findings of histologic examination showed that tumor was present in all patients. For tumor detection, the AUC value for reader 1 was 0.75 (95% confidence interval [CI]: 0.67, 0.84), whereas the AUC value for reader 2 was 0.61 (95% CI: 0.52, 0.71). The AUC values for prediction of ECE were 0.87 (95% CI: 0.80, 0.94) for reader 1 and 0.76 (95% CI: 0.67, 0.85) for reader 2. The AUC values for prediction of SVI were 0.76 (95% CI: 0.62, 0.90) for reader 1 and 0.70 (95% CI: 0.56, 0.85) for reader 2. For all variables, the kappa statistics used to assess interrater agreement between readers were fair (0.45, 0.52, and 0.47 for tumor location, ECE, and SVI, respectively). CONCLUSION: Endorectal MR imaging following radiation therapy can help identify tumor sites and depict ECE and SVI with reasonable accuracy in patients with recurrent prostate cancer.     

Prostate cancer localization with endorectal MR imaging and MR spectroscopic imaging: effect of clinical data on reader accuracy

PURPOSE: To determine the effect of digital rectal examination findings, sextant biopsy results, and prostate-specific antigen (PSA) levels on reader accuracy in the localization of prostate cancer with endorectal magnetic resonance (MR) imaging and MR spectroscopic imaging. MATERIALS AND METHODS: This was a retrospective study of 37 patients (mean age, 57 years) with biopsy-proved prostate cancer. Transverse T1-weighted, transverse high-spatial-resolution, and coronal T2-weighted MR images and MR spectroscopic images were obtained. Two independent readers, unaware of clinical data, recorded the size and location of suspicious peripheral zone tumor nodules on a standardized diagram of the prostate. Readers also recorded their degree of diagnostic confidence for each nodule on a five-point scale. Both readers repeated this interpretation with knowledge of rectal examination findings, sextant biopsy results, and PSA level. Step-section histopathologic findings were the reference standard. Logistic regression analysis with generalized estimating equations was used to correlate tumor detection with clinical data, and alternative free-response receiver operating characteristic (AFROC) curve analysis was used to examine the overall effect of clinical data on all positive results. RESULTS: Fifty-one peripheral zone tumor nodules were identified at histopathologic evaluation. Logistic regression analysis showed awareness of clinical data significantly improved tumor detection rate (P <.02) from 15 to 19 nodules for reader 1 and from 13 to 19 nodules for reader 2 (27%-37% overall) by using both size and location criteria. AFROC analysis showed no significant change in overall reader performance because there was an associated increase in the number of false-positive findings with awareness of clinical data, from 11 to 21 for reader 1 and from 16 to 25 for reader 2. CONCLUSION: Awareness of clinical data significantly improves reader detection of prostate cancer nodules with endorectal MR imaging and MR spectroscopic imaging, but there is no overall change in reader accuracy, because of an associated increase in false-positive findings. A stricter definition of a true-positive result is associated with reduced sensitivity for prostate cancer nodule detection.     

Prostate cancer localization with dynamic contrast-enhanced MR imaging and proton MR spectroscopic imaging

PURPOSE: To prospectively determine the accuracies of T2-weighted magnetic resonance (MR) imaging, dynamic contrast material-enhanced MR imaging, and quantitative three-dimensional (3D) proton MR spectroscopic imaging of the entire prostate for prostate cancer localization, with whole-mount histopathologic section findings as the reference standard. MATERIALS AND METHODS: This study was approved by the institutional review board, and informed consent was obtained from all patients. Thirty-four consecutive men with a mean age of 60 years and a mean prostate-specific antigen level of 8 ng/mL were examined. The median biopsy Gleason score was 6. T2-weighted MR imaging, dynamic contrast-enhanced MR imaging, and 3D MR spectroscopic imaging were performed, and on the basis of the image data, two readers with different levels of experience recorded the location of the suspicious peripheral zone and central gland tumor nodules on each of 14 standardized regions of interest (ROIs) in the prostate. The degree of diagnostic confidence for each ROI was recorded on a five-point scale. Localization accuracy and ROI-based receiver operating characteristic (ROC) curves were calculated. RESULTS: For both readers, areas under the ROC curve for T2-weighted MR, dynamic contrast-enhanced MR, and 3D MR spectroscopic imaging were 0.68, 0.91, and 0.80, respectively. Reader accuracy in tumor localization with dynamic contrast-enhanced imaging was significantly better than that with quantitative spectroscopic imaging (P < .01). Reader accuracy in tumor localization with both dynamic contrast-enhanced imaging and spectroscopic imaging was significantly better than that with T2-weighted imaging (P < .01). CONCLUSION: Compared with use of T2-weighted MR imaging, use of dynamic contrast-enhanced MR imaging and 3D MR spectroscopic imaging facilitated significantly improved accuracy in prostate cancer localization.     

Prostate cancer: prediction of extracapsular extension with endorectal MR imaging and three-dimensional proton MR spectroscopic imaging.

PURPOSE: To determine if the addition of three-dimensional (3D) proton magnetic resonance (MR) spectroscopic imaging to endorectal MR imaging helps diagnose extracapsular extension (ECE) of prostate cancer. MATERIALS AND METHODS: Endorectal MR imaging and 3D MR spectroscopic imaging were performed in 53 patients with prostate cancer before radical prostatectomy. MR imaging studies were evaluated by two independent readers unaware of histopathologic findings. The presence of ECE was graded on a five-point scale. At 3D MR spectroscopic imaging, cancer was diagnosed if the ratio of choline plus creatine to citrate was 2 or more SDs above normal. The accuracy of MR imaging alone was compared with that of combined MR imaging and 3D MR spectroscopic imaging, with use of the step-section histopathologic results as the standard of reference. RESULTS: For the less experienced reader, the addition of 3D MR spectroscopic imaging to MR imaging significantly improved accuracy (area under the receiver operating characteristic curve [Az] = 0.75 vs Az = 0.62, P < .05). For the more experienced reader, the addition improved accuracy but not significantly (Az = 0.86 vs Az = 0.78). The addition also reduced interobserver variability (Az = 0.86 vs Az = 0.75). CONCLUSION: The addition of 3D MR spectroscopic imaging to MR imaging improves accuracy for less experienced readers and reduces interobserver variability in the diagnosis of ECE of prostate cancer.     

Prostate cancer: correlation of MR imaging and MR spectroscopy with pathologic findings after radiation therapy-initial experience

PURPOSE: To prospectively evaluate magnetic resonance (MR) imaging and MR spectroscopy for depiction of local prostate cancer recurrence after external-beam radiation therapy, with step-section pathologic findings as the standard of reference. MATERIALS AND METHODS: Study received institutional approval, and written informed consent was obtained. Study was compliant with Health Insurance Portability and Accountability Act. Sextant biopsy, digital rectal examination, MR imaging, MR spectroscopy, and salvage radical prostatectomy with step-section pathologic examination were performed in nine patients with increasing prostate-specific antigen levels after external-beam radiation therapy. MR imaging criterion for tumor was a focal nodular region of reduced signal intensity at T2-weighted imaging. MR spectroscopic criteria for tumor were voxels with choline (Cho) plus creatine (Cr) to citrate (Cit) ratio ([Cho + Cr]/Cit) of at least 0.5 or voxels with detectable Cho and no Cit in the peripheral zone. Sensitivity and specificity of sextant biopsy, digital rectal examination, MR imaging, and MR spectroscopy were determined by using a prostate sextant as the unit of analysis. For feature analysis, MR imaging and MR spectroscopic findings were correlated with step-section pathologic findings. RESULTS: MR imaging and MR spectroscopy showed estimated sensitivities of 68% and 77%, respectively, while sensitivities of biopsy and digital rectal examination were 48% and 16%, respectively. MR spectroscopy appears to be less specific (78%) than the other three tests, each of which had a specificity higher than 90%. MR spectroscopic feature analysis showed that a metabolically altered benign gland could be falsely identified as tumor by using MR spectroscopic criteria; further analysis of MR spectroscopic features did not lead to improved MR spectroscopic criteria for recurrent tumor. CONCLUSION: In summary, MR imaging and MR spectroscopy may be more sensitive than sextant biopsy and digital rectal examination for sextant localization of cancer recurrence after external-beam radiation therapy.     

Prostate cancer: incremental value of endorectal MR imaging findings for prediction of extracapsular extension

PURPOSE: To assess the incremental value of endorectal magnetic resonance (MR) imaging findings in addition to clinical variables for prediction of extracapsular extension (ECE) in patients with prostate cancer. MATERIALS AND METHODS: In this cohort study, 344 consecutive patients with biopsy-proved prostate cancer underwent endorectal MR imaging prior to surgery; 216 of these patients also underwent MR spectroscopic imaging. MR images were interpreted by 10 attending radiologists. The likelihood of ECE was scored retrospectively on the basis of MR imaging reports. Clinical variables included serum prostate-specific antigen (PSA) level, Gleason score, clinical stage of tumor, greatest percentage of cancer in all core biopsy specimens, percentage of cancer-positive core specimens in all core biopsy specimens, and presence of perineural invasion. For data analysis, receiver operating characteristic (ROC) curves and univariate and multivariate logistic regression analyses were used. Jackknife analysis was used for prediction of probability from a model that included clinical variables as tested comparatively with a model that included the clinical variables plus endorectal MR imaging findings. A difference with P <.05 was considered significant. RESULTS: At univariate analysis, all variables were associated with ECE. At ROC univariate analysis, endorectal MR imaging findings had the largest area under the ROC curve. At multivariate analysis, serum PSA level, percentage of cancer in all core biopsy specimens, and endorectal MR imaging findings (P =.001, P =.001, and P <.001, respectively) were predictors of ECE. Areas under ROC curve for two models, with and without endorectal MR imaging findings, were 0.838 and 0.772, respectively (P =.022). CONCLUSION: A model containing endorectal MR imaging findings has a significantly larger area under the ROC curve than a model containing only clinical variables; thus, endorectal MR imaging findings add incremental value in the prediction of ECE.     

Prostate cancer: detection of extracapsular extension by genitourinary and general body radiologists at MR imaging

PURPOSE: To determine whether predictive value of endorectal magnetic resonance (MR) imaging findings in detection of prostate cancer extracapsular extension (ECE) is significantly affected by the reader's subspecialty experience. MATERIALS AND METHODS: In this cohort study, 344 consecutive patients with biopsy-proved prostate cancer underwent endorectal MR imaging followed by surgery. Likelihood of ECE described in MR imaging reports was compared with clinical predictor variables. ECE was determined from the final pathologic report on specimens resected at surgery. Readers of MR images were classified into genitourinary MR imaging radiologists (n = 4) and general body MR imaging radiologists (n = 6). For data analysis, Wilcoxon rank sum and chi(2) tests, as well as receiver operating characteristic (ROC) curves and univariate and multivariate logistic regression analyses, were used. A difference with P <.05 was considered significant. RESULTS: Univariate analysis results demonstrated that all predictors except clinical stage were significantly associated with detection of ECE in both groups of readers (P <.05). In the genitourinary MR imaging radiologist group of patients, area under the ROC curve for endorectal MR imaging findings (0.833) was larger than areas under the curves for all other predictors (0.566-0.701). In the general body MR imaging radiologist group of patients, area under the ROC curve for endorectal MR imaging findings (0.646) was not larger than areas under the curves for all other predictors (0.582-0.793). Results of multivariate analysis of two models, one with all predictors and another with all predictors except endorectal MR imaging findings, demonstrated a significant increase in area under the ROC curve with endorectal MR images interpreted by genitourinary MR imaging radiologists (P =.019 and.31, respectively). CONCLUSION: Endorectal MR imaging findings are significant predictors for detection of ECE when MR images are interpreted by genitourinary radiologists experienced with MR imaging of the prostate.     

Local staging of prostate cancer: comparative accuracy of T2-weighted endorectal MR imaging and transrectal ultrasound

ObjectiveThe objective of this study was to compare the accuracy of T2-weighted magnetic resonance (MR) imaging and transrectal ultrasound (TRUS) for staging of prostate cancer.Material and methodsA total of 101 men with biopsy-proven prostate cancer undergoing both T2-weighted endorectal MR imaging and B-mode TRUS for local tumor staging prior to radical prostatectomy were retrospectively identified. Three MR readers rated the likelihood of locally advanced disease using a 5-point scale. An ultrasound reader performed the same rating. Staging accuracy was compared using receiver operating characteristic curves.ResultsStaging accuracy was not significantly different between MR imaging (A_z = 0.69–0.70) and TRUS (A_z = 0.81, P>.05).ConclusionsT2-weighted MR imaging demonstrates comparable accuracy to B-mode TRUS for depicting locally invasive prostate cancer.     

Detection of prostate cancer with MR spectroscopic imaging: an expanded paradigm incorporating polyamines

PURPOSE: To characterize benign and malignant prostate peripheral zone (PZ) tissue retrospectively by using a commercial magnetic resonance (MR) spectroscopic imaging package and incorporating the choline plus creatine-to-citrate ratio ([Cho + Cr]/Cit) and polyamine (PA) information into a statistically based voxel classification procedure. MATERIALS AND METHODS: The institutional review board approved this HIPAA-compliant study and waived the requirement for informed consent. Fifty men (median age, 60 years; range, 44-69 years) with untreated biopsy-proved prostate cancer underwent combined endorectal MR imaging and MR spectroscopic imaging. Commercial software was used to acquire and process MR spectroscopic imaging data. The (Cho + Cr)/Cit and the PA level were tabulated for each voxel. The PA level was scored on a scale of 0 (PA undetectable) to 2 (PA peak as high as or higher than Cho peak). Whole-mount step-section histopathologic analysis constituted the reference standard. Classification and regression tree analysis in a training set generated a decision-making tree (rule) for classifying voxels as malignant or benign, which was validated in a test set. Receiver operating characteristic and generalized estimating equation regression analyses were used to assess accuracy and sensitivity, respectively. RESULTS: The median (Cho + Cr)/Cit was 0.55 (mean +/- standard deviation, 0.59 +/- 0.03) in benign and 0.77 (mean, 1.08 +/- 0.20) in malignant PZ voxels (P = .027). A significantly higher percentage of benign (compared with malignant) voxels had higher PA than choline peaks (P < .001). In the 24-patient training set (584 voxels), the rule yielded 54% sensitivity and 91% specificity for cancer detection; in the 26-patient test set (667 voxels), it yielded 42% sensitivity and 85% specificity. The percentage of cancer in the voxel at histopathologic analysis correlated positively (P < .001) with the sensitivity of the classification and regression tree rule, which was 75% in voxels with more than 90% malignancy. CONCLUSION: The statistically based classification rule developed indicated that PAs have an important role in the detection of PZ prostate cancer. With commercial software, this method can be applied in clinical settings.     

MR imaging and MR spectroscopy in prostate cancer management

Currently, endorectal coil MR imaging has the ability to improve accuracy in staging of localized prostate cancer. The addition of MR spectroscopic imaging has further improved the sensitivity of MR imaging for intraprostatic tumor localization. Additional refinements and techniques are expected to further improve the performance of MR imaging for prostate cancer imaging and to aid in patient management. Further studies are required to identify the ideal role for MR imaging in the diagnosis and management of prostate cancer.     

Prediction of organ-confined prostate cancer: incremental value of MR imaging and MR spectroscopic imaging to staging nomograms

PURPOSE: To assess retrospectively the incremental value of endorectal coil magnetic resonance (MR) imaging and combined endorectal MR imaging-MR spectroscopic imaging to the staging nomograms for predicting organ-confined prostate cancer (OCPC). MATERIALS AND METHODS: The institutional review board approved this HIPAA-compliant study and issued a waiver of informed consent for review of the MR reports and clinical data. Between November 1, 1999, and November 1, 2004, 229 patients underwent endorectal MR imaging and 383 underwent combined endorectal MR imaging-MR spectroscopic imaging before radical prostatectomy. Mean patient age was 58 years (range, 32-74 years). MR studies were interpreted prospectively by 12 radiologists who were informed of patients' clinical data. On the basis of the MR reports, the risks of extracapsular extension, seminal vesicle invasion, and lymph node metastasis were scored retrospectively from 1 to 5; the highest score was subtracted from 6 to determine a score (from 1 to 5) for the likelihood of OCPC on MR studies. The staging nomograms were used to calculate the likelihood of OCPC on the basis of serum prostate-specific antigen level, Gleason grade at biopsy, and clinical stage. Histopathologic findings constituted the reference standard. Logistic regression was used to estimate the multivariable relations between OCPC and MR findings. The area under the receiver operator characteristic curve was calculated for each model. The jackknife method was used for bias correction. RESULTS: MR findings contributed significant incremental value (P 相似文献   

Magnetic resonance spectroscopic imaging of benign prostatic tissue: findings at 3.0 T compared to 1.5 T-initial experience

In a retrospective study of 71 voxels of benign peripheral zone tissue from 3 men who underwent endorectal magnetic resonance (MR) spectroscopic imaging of the prostate at both 1.5 and 3 T, 21 voxels that appeared more malignant at 3 T to either of two readers demonstrated significantly higher levels of choline and polyamines at 3 T compared to 1.5 T using a Wilcoxon ranked-sum test; awareness of this selective amplification of these metabolic signals at high field strength may help avoid overdiagnosis of prostate cancer.     

Prediction of seminal vesicle invasion in prostate cancer: incremental value of adding endorectal MR imaging to the Kattan nomogram

PURPOSE: To retrospectively determine whether endorectal magnetic resonance (MR) imaging findings contribute incremental value to the Kattan nomogram for predicting seminal vesicle invasion (SVI) in patients with prostate cancer. MATERIALS AND METHODS: The institutional review board issued a waiver of authorization, which included a waiver of informed consent, for this HIPAA-compliant study. From October 2000 through January 2005, 573 patients (mean age, 58.3 years; age range, 36-86 years) underwent endorectal MR imaging before prostate cancer surgery. The endorectal MR imaging results had been prospectively interpreted by seven radiologists, and the likelihood of SVI was retrospectively scored on the basis of radiologists' written reports. MR imaging findings, individual clinical variables (serum prostate-specific antigen [PSA] level, Gleason grade, clinical stage, greatest percentage of cancer in all biopsy cores, percentage of positive cores in all biopsy cores, and perineural invasion), and the Kattan nomogram were evaluated with respect to SVI prediction; surgical pathologic analysis was used as the reference standard. Logistic regression and receiver operating characteristic (ROC) curve analyses were performed. RESULTS: At pathologic analysis, 28 (4.9%) of 573 patients had SVI. At univariate analysis, endorectal MR imaging results and all clinical variables except the percentage of positive biopsy cores were significantly associated with SVI (P<.02); endorectal MR imaging (0.76) had a larger area under the ROC curve (AUC) than any clinical variable (0.62-0.73). At multivariate analysis, endorectal MR imaging results, Gleason grade, PSA level, and the percentage of cancer in all biopsy cores were significantly associated with SVI (P相似文献   

Prostate cancer: endorectal MR imaging and MR spectroscopic imaging--distinction of true-positive results from chance-detected lesions

PURPOSE: To retrospectively investigate size criteria for the identification of chance-detected lesions at endorectal magnetic resonance (MR) imaging and MR spectroscopic imaging of prostate cancer. MATERIALS AND METHODS: Approval of the committee on human research and written informed consent were obtained. This study was HIPAA compliant. Endorectal MR imaging and MR spectroscopic imaging were performed with a 1.5-T MR imager in 48 men with a mean age of 59 years (age range, 47-75 years) prior to radical prostatectomy. Two independent readers recorded the size and location of all suspected peripheral zone tumor nodules on MR images alone and on images obtained with combined MR imaging and MR spectroscopic imaging. Nodules detected at MR imaging were classified as matched lesions if tumor was present in the same location at step-section histopathologic review. For all matched lesions, kappa values were calculated to examine agreement between measured and actual tumor size. Lesions that were overmeasured at MR imaging with a kappa value of less than 0.2 were considered chance-detected lesions. RESULTS: At MR imaging, two of 27 and four of 35 matched lesions for readers 1 and 2, respectively, were chance-detected lesions. The corresponding numbers of lesions at combined MR imaging and MR spectroscopic imaging were one of 21 and one of 31, respectively. In all but two cases, the measured diameter of chance-detected lesions was more than twice that of the diameter at histopathologic analysis. By using this diameter threshold to distinguish true-positive results, the mean diameter of detected tumors at histopathologic analysis was 15 mm compared with 4 mm for both undetected and chance-detected tumors (P < .05). CONCLUSION: To ensure uniformity in the comparison of scientific studies, peripheral zone tumors detected at MR imaging and MR spectroscopic imaging of the prostate that are in the same location as tumors detected at histopathologic review should be considered chance-detected lesions if the MR transverse diameter is more than twice the histopathologic transverse diameter.     

Correlation of proton MR spectroscopic imaging with gleason score based on step-section pathologic analysis after radical prostatectomy

PURPOSE: To determine whether hydrogen 1 magnetic resonance (MR) spectroscopic imaging can be used to predict aggressiveness of prostate cancer. MATERIALS AND METHODS: All patients gave informed consent according to an institutionally approved research protocol. A total of 123 patients (median age, 58 years; age range, 40-74 years) who underwent endorectal MR imaging and MR spectroscopic imaging between January 2000 and December 2002 were included. MR imaging and spectroscopy were performed by using combined pelvic phased-array and endorectal probe. Water and lipids were suppressed, and phase-encoded data were acquired with 6.2-mm resolution. Voxels in the peripheral zone were considered suspicious for cancer if (Cho + Cr)/Cit was at least two standard deviations above the normal level, where Cho represents choline-containing compounds, Cr represents creatine and phosphocreatine, and Cit represents citrate. Correlation between metabolite ratio and four Gleason score groups identified at step-section pathologic evaluation (3 + 3, 3 + 4, 4 + 3, and > or =4 + 4) was assessed with generalized estimating equations. RESULTS: Data from 94 patients were included. Pathologic evaluation was used to identify 239 lesions. Overall sensitivity of MR spectroscopic imaging was 56% for tumor detection, increasing from 44% in lesions with Gleason score of 3 + 3 to 89% in lesions with Gleason score greater than or equal to 4 + 4. There was a trend toward increasing (Cho + Cr)/Cit with increasing Gleason score in lesions identified correctly with MR spectroscopic imaging. Tumor volume assessed with MR spectroscopic imaging increased with increasing Gleason score. CONCLUSION: MR spectroscopic imaging measurement of prostate tumor (Cho + Cr)/Cit and tumor volume correlate with pathologic Gleason score. There is overlap between MR spectroscopic imaging parameters at various Gleason score levels, which may reflect methodologic and physiologic variations. MR spectroscopic imaging has potential in noninvasive assessment of prostate cancer aggressiveness.     

Prostate cancer: localization with three-dimensional proton MR spectroscopic imaging--clinicopathologic study.

PURPOSE: To assess the efficacy of combined magnetic resonance (MR) imaging and three-dimensional (3D) proton MR spectroscopic imaging in the detection and localization of prostate cancer. MATERIALS AND METHODS: MR imaging and 3D MR spectroscopic imaging examinations were performed in 53 patients with biopsy-proved prostate cancer and subsequent radical prostatectomy with step-section histopathologic examination. The prostate was divided into sextants. At MR imaging, the presence or absence of cancer in the peripheral zone of each sextant was assessed independently by two readers (readers 1 and 2) unaware of the findings at 3D MR spectroscopic imaging and histopathologic examination. At 3D MR spectroscopic imaging, cancer was diagnosed as possible if the ratio of choline plus creatine to citrate exceeded 2 SD above population norms or as definite if that ratio exceeded 3 SDs above the norm. RESULTS: On the basis of sextants, sensitivity and specificity, respectively, for MR imaging were 77% and 61% (reader 1) and 81% and 46% (reader 2) with moderate interreader agreement (kappa = 0.43). The 3D MR spectroscopic imaging diagnosis of definite cancer had significantly higher specificity (75%, P < .05) but lower sensitivity (63%, P < .05). Receiver operating characteristic analysis showed significantly (P < .001) improved tumor localization for both readers when 3D MR spectroscopic imaging was added to MR imaging. High specificity (up to 91%) was obtained when combined MR imaging and 3D MR spectroscopic imaging indicated cancer, whereas high sensitivity (up to 95%) was obtained when either test alone indicated a positive result. CONCLUSION: The addition of 3D MR spectroscopic imaging to MR imaging provides better detection and localization of prostate cancer in a sextant of the prostate than does use of MR imaging alone.     

Organ-confined prostate cancer: effect of prior transrectal biopsy on endorectal MRI and MR spectroscopic imaging

OBJECTIVE: Our aim was to determine the effect of prior transrectal biopsy on endorectal MRI and MR spectroscopic imaging findings in patients with organ-confined prostate cancer. MATERIALS AND METHODS: Endorectal MRI and MR spectroscopic imaging were performed in 43 patients with biopsy-proven prostate cancer before radical prostatectomy confirming organ-confined disease. For each sextant, two independent reviewers scored the degree of hemorrhage on a scale from 1 to 5 and recorded the presence or absence of capsular irregularity. A spectroscopist recorded the number of spectrally degraded voxels in the peripheral zone. The outcome variables of capsular irregularity and spectral degradation were correlated with the predictor variables of time from biopsy and degree of hemorrhage after biopsy. RESULTS: Capsular irregularity was unrelated to time from biopsy or to degree of hemorrhage. Spectral degradation was inversely related to time from biopsy (p < 0.01); the mean percentage of degraded peripheral zone voxels was 18.5% within 8 weeks of biopsy compared with 7% after 8 weeks. Spectral degradation was unrelated to the degree of hemorrhage. CONCLUSION: In organ-confined prostate cancer, capsular irregularity can be seen at any time after biopsy and is independent of the degree of hemorrhage, whereas spectral degradation is seen predominantly in the first 8 weeks after biopsy. MRI staging criteria and guidelines for scheduling studies after biopsy may require appropriate modification.     

Accuracy of MR imaging for staging prostate cancer: a meta-analysis to examine the effect of technologic change

RATIONALE AND OBJECTIVES: The purpose of this study was to summarize the accuracy of magnetic resonance (MR) imaging for staging prostate cancer and to determine the effect of high magnetic field strength, use of the endorectal coil, use of fast spin-echo (SE) imaging, and study size on staging accuracy. MATERIALS AND METHODS: A literature search and review yielded 27 studies comparing MR imaging to a pathologic standard in patients with clinically limited prostate cancer. Subgroup analyses examined magnetic field strength, use of an endorectal coil, use of fast SE imaging, publication date, and study size. RESULTS: A summary receiver operating characteristic curve for all studies had a maximum joint sensitivity and specificity of 74%. At a specificity of 80% on this curve, sensitivity was 69%. Subgroup analyses showed that fast SE imaging was statistically significantly more accurate than conventional SE techniques (P < .001). Unexpectedly, studies employing higher magnetic field strength and those employing an endorectal coil were less accurate. CONCLUSION: Seemingly small technologic advances may influence test accuracy. Early and small studies, however, may overstate accuracy because of publication bias, bias in small samples, or earlier studies being performed by the experts who developed the technology itself.     

Prostatic biopsy directed with endorectal MR spectroscopic imaging findings in patients with elevated prostate specific antigen levels and prior negative biopsy findings: early experience

PURPOSE: To prospectively evaluate the accuracy of transrectal ultrasonography (US)-guided biopsy directed with magnetic resonance (MR) spectroscopic imaging in patients with an elevated prostate specific antigen (PSA) level and negative findings at prior biopsy by using subsequent biopsy results as the reference standard. MATERIALS AND METHODS: The committee on human research approved this study, and written informed consent was obtained. MR imaging and MR spectroscopic imaging were performed in 42 men (age range, 45-75 years; average age, 63.3 years; median age, 65 years) with negative findings at two or more prostatic biopsies and at digital rectal examination. MR spectroscopic data were rated on a scale of 1 (benign) to 5 (malignant) on the basis of standardized metabolic criteria. Abnormal voxels were overlaid on the corresponding transverse transrectal US images and used to perform voxel-guided biopsy of the prostate. All patients subsequently received an extended-pattern biopsy scheme. RESULTS: Thirty-one of 42 patients demonstrated metabolic abnormalities that were suspicious for cancer (voxels with scores > or = 4). Eleven patients with negative MR spectroscopic imaging results also had negative biopsy findings. Cancer was detected in 17 (55%) of 31 men with positive MR spectroscopic imaging findings (voxels with scores > or = 4) with a sensitivity of 100%, specificity of 44%, positive predictive value of 55%, negative predictive value of 100%, and accuracy of 67%. In men with at least one spectroscopic voxel with a score of 5 (12 of 17 men), the sensitivity, specificity, positive and negative predictive values, and accuracy were 71%, 84%, 75%, 81%, and 79%, respectively. CONCLUSION: Metabolic data from MR spectroscopic imaging can be transferred to transrectal US images and used to sample regions of cancer in men with rising PSA levels and negative findings at prior biopsy with good accuracy.