Usefulness of Preoperative MRI Diagnosis in Prostatic Adenocarcinoma

Background :
We examined the reliability of an MRI diagnosis prior to radical prostatectomy for prostate cancer.
Methods :
A radical prostatectomy was performed in 24 patients with prostate cancer. Resected specimens were fixed and 5 mm step sections vertical to the urethra were prepared to resemble MRI images. We compared this pathological map with the preoperative MRI diagnosis which included capsular or seminal vesicle invasion and tumor localization in the prostate. We defined a new criterion for the presence of capsular invasion as a chemical shift that occurred on the rectal side on T1 -weighted images 5 minutes after gadolinium (Gd) enhancement and the periprostatic venous plexus was not serial. We also examined 4 diagnostic factors of tumor localization including a low-signal intensity area detected in the peripheral zone on T2-weighted images, the presence of an enhanced area on Gd-enhanced T1-weighted images, and a low T2 with either Gd-enhanced or nonenhanced T1-weighted images.
Results :
The accuracy of a preoperative MRI diagnosis of capsular invasion was 16.7% using the conventional criteria, but 88.9% adding the new criterion. The accuracy of predicting seminal vesicle invasion was 63.2% in a group using a body surface coil compared to 75% in the group using an endorectal surface coil. The accuracy, positive predictive value, sensitivity and specificity of diagnosing tumor localization were 69%, 74.4%, 35.1%, and 91.8%, respectively.
Conclusion :
This new criterion proved superior for diagnosing capsular invasion in prostate cancer patients. Also, analysis of tumor localization in the peripheral zone demonstrated that cancer detection is increased if the low-signal intensity area is enhanced by Gd.     

Local staging with magnetic resonance imaging after neoadjuvant hormonal therapy for prostate cancer]

We retrospectively studied the staging accuracy of magnetic resonance (MR) imaging after neoadjuvant hormonal therapy (NAH) for 21 localized prostate cancers. MR imaging was performed using a 1.5-Tesla magnetic resonance system with a pelvic phased array coil. T2-weighted MR images were obtained on axial and coronal planes, and T1-weighted MR images using the dynamic technique with Gd-DTPA bolus enhancement were obtained in axial planes for each patient. On T2-weighted imaging, the signal intensity of the normal tissue in the peripheral zone became lower after NAH. Therefore, it was more difficult to detect residual malignant lesions in many cases than before NAH. The accuracy of T staging for prostate cancer after NAH in MRI was 71%. The accuracy, sensitivity, and specificity of the extracapsular invasion was 76%, 0% and 94%, respectively, and those of the seminal vesicular invasion 85%, 0% and 100%, respectively. While 2 of the 4 patients judged as downstaged cases in MRI showed corresponding pathological findings, 5 of the 21 cases (23.8%) were underdiagnosed. Local staging with only MRI for prostate cancer after NAH seems to have limits in applicability.     

Staging and tissue characterization of prostate carcinoma: role of endorectal MR imaging and MR spectroscopy

The role of magnetic resonance (MR) imaging and MR spectroscopy with an endorectal coil in tissue characterization and local staging was reviewed. Endorectal coil (ERC) MR imaging demonstrated the detailed zonal anatomy of the normal prostate. The sensitivity and specificity of staging prostate cancer for ERC MR imaging was superior to both conventional MR imaging and transrectal ultrasound. ERC MR imaging is the most accurate noninvasive method of staging prostate cancer. However, the accuracy of the diagnosis made by inexperienced radiologists was significantly inferior to that made by experienced radiologists. Endorectal MRI failed to differentiate benign from malignant lesions in some patients demonstrating low signal intensity on T2-weighted imaging in the peripheral zone. MR spectroscopy may provide additional information on tissue characterization, monitoring after treatment and staging.     

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

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.     

多参数磁共振成像技术在前列腺癌诊断中的应用价值

目的:研究多参数磁共振成像技术(MP-MRI)诊断前列腺癌(PCa)的应用价值。方法:分析62例PCa临床疑似患者的T2加权成像、弥散加权成像、体素内无规则运动核磁成像及动态对比增强成像等MRI数据。结果:62例患者中,MP-MRI诊断PCa的诊断符合率为87.1%,灵敏度为90.5%,特异度为85.4%。结论:MP-MRI在PCa的临床诊断中具有重要价值。     

The potential role of prebiopsy magnetic resonance imaging combined with prostate-specific antigen density in the detection of prostate cancer

Aim:   Two-thirds of patients with a gray-zone prostate-specific antigen (PSA) level undergo unnecessary biopsy. Sensitivity is not yet sufficient to permit the use of modified PSA parameters or magnetic resonance (MR) imaging alone for prostate cancer screening. Thus, we evaluated the combination of MR imaging and PSA density (PSAD) for specificity and sensitivity.
Methods:   During the period April 2004 through March 2006, 185 patients with a PSA level of 4.0–10.0 ng/mL underwent MR imaging and transrectal ultrasonography-guided 8-core biopsy (systemic sextant biopsy of the peripheral zone plus two cores of transition zone). All MR images were interpreted prospectively by two radiologists. An image was considered positive for prostate cancer if any feature indicated a cancerous lesion. Receiver operating characteristic (ROC) curves were used to compare the usefulness of the PSA level, PSAD and PSA transitional zone density (PSATZ) for the detection of prostate cancer.
Results:   Of the 185 patients, 62 had prostate cancer. Sensitivity and specificity of the axial T2-weighted MR imaging findings for cancer detection were 79.0% and 59.4%, respectively. The area under the ROC curve was 0.590 for the PSA level, 0.718 for PSAD and 0.695 for PSATZ. MR imaging findings and PSAD were shown by multivariate analysis to be statistically significant independent predictors of prostate cancer ( P  < 0.001). With a PSAD cut-off value of 0.111, sensitivity was 96.8%, but specificity was 19.5%. Combining MR imaging findings with PSAD increased the specificity to 40% and retained 95% sensitivity.
Conclusion:   MR imaging findings combined with PSAD provide high sensitivity and improve the specificity for the early detection of prostate cancer.     

Combined magnetic resonance spectroscopy and dynamic contrast-enhanced imaging for prostate cancer detection

BackgroundThe use of magnetic resonance spectroscopy imaging (MRSI) and dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) have emerged as a valid diagnostic tools for prostate cancer (CaP).MethodsMen with PSA levels below 10 ng/ml were enrolled in a prospective cohort study and underwent combined MRSI and DCE-MRI and transrectal ultrasound-guided prostate biopsy. Imaging was performed using a 1.5 T MR scanner (Symphony TIM; Siemens, Erlangen, Germany) with an endorectal coil (Medrad; Pittsburg, PA), inflated with 60 cc of air. Three-dimensional magnetic resonance spectroscopic data were acquired by using water and a lipid-suppressed double-spin-echo point-resolved spectroscopy sequence, which was optimized for quantitative detection of both choline and citrate. Dynamic contrast-enhanced MRI sequences were obtained with 3D T1-weighted FLASH images before and during rapid bolus administration of intravenous paramagnetic contrast medium gadoteric acid. Specificity, sensitivity, positive predictive value, negative predictive value, and accuracy were computed considering patients, each of the 2 lobes, each of the 6 sextants, and each 12th part of the prostate gland as single measurements.ResultsOverall, 106 patients were included in the analysis. Median age was 65.9 years (range, 61.2–70.5 years) and median PSA level at study entry was 7.1 ng/ml (range, 2.5–9.9). CaP was detected at biopsy in 24 patients (22.6 % of the population) with a median Gleason score of 8 (range 4–10). Diagnostic accuracy of combined MRSI and DCE-MRI was 85%, sensitivity was 71%, and specificity was 48%, considering patients as single measurements, with a negative predictive value of 91%, but a positive predictive value of only 19%. Positive predictive value of the examination improved to 25% for patients who repeated biopsy.ConclusionsAlthough this study confirms the potential usefulness of MRI for the diagnosis of CaP, the positive predictive value obtained was unacceptably low due to the high number of false positives recorded. Nevertheless, the high negative predictive value of the examination may serve to avoid unnecessary biopsies. Future research should be directed at assessing the value of combining MRI-based techniques with novel biochemical markers for the diagnosis of CaP in patients with low PSA levels.     

磁共振观察宫颈癌放疗后盆部骨髓变化

目的分析宫颈癌放疗中与放疗后盆部骨髓MR改变。探讨MR成像对显示盆部骨髓损伤的临床价值。方法48例经病理证实的宫颈癌患者在放射治疗前及治疗中和治疗后不同时间段行盆腔的轴位SE T1WI，轴位及矢状位TSE T2WI，冠状位SPIR，以及Gd—DTPA增强后T1WI SE的轴位、冠状位、矢状位扫描。在MR图像上观察盆部骨髓在放疗前后的信号改变。结果骨髓信号最早出现改变是在外照射开始后第8天，患者受照剂量在12Gy时。放疗早期，骨髓在T1WI，T2WI及SPIR序列上信号升高，T1WI增强扫描见强化。放疗晚期，骨髓的T1WI，T2WI信号升高程度增加，SPIR序列出现信号降低，T1WI增强扫描，骨髓强化不明显。53％的患者在T1WI、T2WI上，18％的患者在SPIR序列上见照射野外骨髓信号有改变。结论宫颈癌外照射放疗可引起照射野内、外骨髓多种MR信号改变，并有一定规律性，对宫颈癌临床治疗有指导意义。     

The progress in diagnostic imaging for staging of bladder and prostate cancer: endorectal magnetic resonance imaging and magnetization transfer contrast]

We retrospectively studied the staging accuracy of endorectal magnetic resonance imaging (MRI) in comparison with transrectal ultrasound examination (TRUS) for 71 localized bladder cancers and 19 localized prostate cancers (PC) radically resected. The accuracy of clinical staging for bladder cancer in endorectal MRI and TRUS was 85.9% and 69.2%, respectively. The presence or absence of the continuity of submucosal enhancement on T2-weighted MRI images could be useful for the staging of bladder cancer. The accuracy of the seminal vesicular invasion for prostate cancer in endorectal MRI and TRUS was 95% and 63%, respectively. To determine whether magnetization transfer contrast (MTC) provides additional information in the diagnosis of prostate cancer, the magnetization transfer ratios (MTRs) were calculated in 22 patients with PC, 5 with benign prostatic hyperplasia (BPH) and 4 controls. The mean MTR in the peripheral zone of the normal prostate (8.0% +/- 3.4 [standard deviation]) showed a statistically significant decrease relative to that in the inner zone of the normal prostate (27.4% +/- 3.4, p < 0.01), BPH (25.5% +/- 3.7, p < 0.01), pre-treatment PC (30.6% +/- 5.9, p < 0.01), and PC after hormonal therapy (20.3% +/- 6.3, p < 0.01). The mean MTR in pre-treatment PC was significantly higher than that in BPH, or in PC after hormonal therapy (p < 0.01). MTC was considered to be useful for conspicuity of prostate cancer lesion.     

Endorectal magnetic resonance imaging staging of prostate cancer

BACKGROUND: There are important treatment and prognostic implications in distinguishing between organ-confined prostate cancer that has spread locally outside the capsule and that which has spread into the seminal vesicles. This study is the first Australian study to report local accuracy for the locoregional staging of prostate cancer with endorectal magnetic resonance imaging (MRI). METHODS: From July 2002 to December 2005, 129 patients were referred for endorectal MRI for all indications. Inclusion criteria were biopsy-proven prostate cancer, minimum 4 weeks from previous biopsy and radical retropubic prostatectomy within 12 months of MRI. This yielded 47 patients. Those with prior hormonal and neoadjuvant radiotherapy or significant postbiopsy haemorrhage were excluded. In addition, those patients examined with our alternate-contrast-enhanced protocol were also excluded. A total of 38 patients met all inclusion criteria. A General Electric 1.5-T whole-body MR imaging unit with an endorectal coil was used with interpretation by two genito-urinary MR radiologists. Final histopathological report was used for correlation. RESULTS: Median age was 60 years with a range 44-72 years. Median prostate-specific antigen was 6.3 with a range of 2-82, and median Gleason score was 6 with a range of 5-8. Sensitivity, specificity and accuracy for extracapsular extension and seminal vesicle invasion were 69, 82 and 76% and 60, 100 and 95%, respectively. For extraprostatic extension, 71, 86 and 79%, respectively. CONCLUSIONS: Staging accuracy is similar to internationally published standards. Improvements in hardware and software and increased reader experience will add value to the local Australian prostate imaging programme.     

Diagnosis of symptomatic disc by magnetic resonance imaging: T2-weighted and gadolinium-DTPA-enhanced T1-weighted magnetic resonance imaging

Although radial tear of the annulus fibrosus can be detected on T2-weighted and Gd-DTPA-enhanced magnetic resonance (MR) images, the association between the annular tear on MR images and the symptomatic discs is unclear. The purpose of this study was to investigate the relationship between T2-weighted, gadolinium-DTPA-enhanced MR images and pain response through discography in patients with chronic low back pain. A total of 56 lumbar discs from 23 patients with chronic low back pain (13 to 47 years old) underwent MR imaging (T2-weighted, gadolinium-DTPA-enhanced MR images) followed by provocative discography. The sensitivity, specificity, positive predictive value, and negative predictive value of T2-weighted and gadolinium-DTPA-enhanced MR images in detecting the symptomatic discs were calculated. The sensitivity, specificity, positive predictive value, and negative predictive value of T2-weighted images in detecting the symptomatic disc were 94%, 71%, 59%, and 97%, respectively. The sensitivity, specificity, positive predictive value, and negative predictive value of gadolinium-DTPA-enhanced images were 71%, 75%, 56%, and 86%, respectively. The high sensitivity and the high negative predictive value of T2-weighted MR imaging in detecting the symptomatic disc indicated that MR imaging can be a useful screening tool in avoiding unnecessary discography in patients with chronic low back pain.     

Bedeutung von endorektaler Kernspintomographie und transrektaler Sonographie beim lokalen Staging des Prostatakarzinoms

METHODS: We assessed the staging accuracy of endorectal magnetic resonance imaging (eMRI) and transrectal ultrasonography (TRUS) for localized prostate cancer. 54 patients with biopsy proven prostate cancer underwent TRUS and eMRI prior to radical retropubic prostatectomy. The MR images were prospectively interpreted by two radiologists. These findings were compared with the histopathological results. RESULTS: Overall accuracy of eMRI in defining local tumor stage was 93% by radiologist A and 56% by radiologist B. Overall accuracy by TRUS was 63%. Analysis of interobserver agreement showed a poor correlation regarding MRI studies. Endorectal MRI was more sensitive than TRUS for detecting capsular penetration and seminal vesicle involvement. TRUS revealed a relatively high specificity and was superior to eMRI in this regard. CONCLUSION: This series shows the current limited value of TRUS and eMRI for planning treatment in patients with clinically localized prostate cancer.     

Multiparametric MRI is helpful to predict tumor focality, stage, and size in patients diagnosed with unilateral low-risk prostate cancer

To study the staging accuracy of multiparametric magnetic resonance imaging (MRI) in patients showing unilateral low-risk cancer on prostate biopsy. A total of 58 consecutive patients with low-risk cancer (D'Amico classification) and unilateral cancer involvement on prostate biopsies were included prospectively. All patients underwent multiparametric endorectal MRI before radical prostatectomy, including T2-weighted (T2W), diffusion-weighted (DW) and dynamic contrast enhanced (DCE) sequences. Each gland was divided in eight octants. Tumor foci >0.2?cm(3) identified on pathological analysis were matched with MRI findings. Pathological examination showed tumor foci >0.2?cm(3) in 50/58 glands (86%), and bilateral tumor (pathological stagepT2c) in 20/58 (34%). For tumor detection in the peripheral zone (PZ), T2W+DWI+DCE performed significantly better than T2W+DWI and T2W alone (P<0.001). In the transition zone (TZ), only T2W+DWI performed better than T2W alone (P=0.02). With optimal MR combinations, tumor size was correctly estimated in 77% of tumor foci involving more than one octant. Bilateral tumors were detected in 80% (16/20) of cases. In patients with unilateral low-risk prostate cancer on biopsy, multiparametric MRI can help to predict bilateral involvement. Multiparametric MRI may therefore have a prognostic value and help to determine optimal treatment in such patients.     

The role of magnetic resonance imaging in targeting prostate cancer in patients with previous negative biopsies and elevated prostate‐specific antigen levels

In the past 20 years, magnetic resonance imaging (MRI) has developed rapidly, along with the management of localized prostate cancer. We summarize current data on the efficacy of MRI for targeting cancer, compared with biopsies, in patients with previous negative prostate biopsies and persistently elevated prostate‐specific antigen (PSA) levels. The key clinical question is how many men benefit by having had prostate cancer detected purely because of the MRI‐targeted, as opposed to standard scheme, biopsies. We reviewed all available databases for prospective studies in patients having MRI and prostate biopsy with previous negative biopsies and persistently elevated PSA levels. Six studies fulfilled the selection criteria, with 215 patients in all; in these studies, the cancer‐detection rate at repeat biopsy was 21–40%. For MRI or combined MRI/MR spectroscopy, the overall sensitivity for predicting positive biopsies was 57–100%, the specificity 44–96% and the accuracy 67–85%. In five studies, specific MRI‐targeted biopsies and standard cores were taken, with a significant proportion (34/63, 54%) having cancer detected purely because of the MRI‐targeted cores. The value of endorectal MRI and MR spectroscopy in patients with elevated PSA levels and previous negative biopsies to target peripheral zone tumours appears to be significant. Although more data obtained with current technologies are needed, published results to data are encouraging. A comparison study and cost‐benefit analysis of MRI‐targeted vs saturation biopsy in this group of patients would also be ideal, to delineate any advantages.     

Limited value of endorectal magnetic resonance imaging and transrectal ultrasonography in the staging of clinically localized prostate cancer

OBJECTIVE: To examine the role of endorectal magnetic resonance imaging (eMRI) and transrectal ultrasonography (TRUS) for clinically localized prostate cancer and to assess interobserver agreement in interpreting MRI studies. PATIENTS AND METHODS: Fifty-four patients with biopsy-confirmed prostate cancer underwent TRUS and eMRI before radical retropubic prostatectomy. The MR images were prospectively interpreted by two radiologists with special expertise in this field. The criteria evaluated prospectively in each patient were extracapsular extension (ECE) and seminal vesicle invasion (SVI). The results were correlated with the histopathological findings after radical prostatectomy. RESULTS: At pathology, 27 patients had stage pT2, 15 had stage pT3a and 12 had stage pT3b lesions. The overall accuracy of eMRI in defining local tumour stage was 93% by radiologist A and 56% by radiologist B; the overall accuracy by TRUS was 63%. There was a poor correlation for the MRI studies between observers. The eMRI was more sensitive than TRUS for detecting ECE and SVI in organ-confined prostate cancer. TRUS had a relatively high specificity for ECE and SVI, and was better than eMRI in this regard. CONCLUSION: Whereas MRI tended to over-stage, TRUS under-staged prostate cancer. This series shows the current limited value of TRUS and eMRI for planning treatment in patients with clinically localized prostate cancer. Treatment decisions should not be altered based on TRUS or eMRI findings alone.     

A new staging criterion for bladder carcinoma using gadolinium-enhanced magnetic resonance imaging with an endorectal surface coil: a comparison with ultrasonography

OBJECTIVE: To evaluate the accuracy of a new staging criterion, submucosal linear enhancement (SLE) on gadolinium-diethylenetriamine-pentaacetic acid-enhanced T1-weighted magnetic resonance imaging (MRI) using an endorectal surface coil (endorectal enhanced MRI), and to compare the accuracy of this method with that of transurethral ultrasonography (TUUS). PATIENTS AND METHODS: The study included 71 patients with bladder tumours (63 men and eight women, mean age 65.5 years, range 31-85). The SLE coincided with abundant submucosal vascular beds, as reported in a previous study. When the SLE beneath the tumour maintained continuity, the tumour was diagnosed as superficial (/= T2a). Superficial muscle invasion (less than half the muscle layer) and deep muscle invasion (more than half the muscle layer) were classified as T2a and T2b, respectively. When the tumour formed an extravesical mass, the tumour was classified as T3b. RESULTS: The staging accuracy for bladder tumours using SLE on endorectal-enhanced MRI or TUUS was 83% and 60%, respectively (P < 0.01). Using the SLE, muscle invasion of bladder tumour was diagnosed with an accuracy of 87%, a sensitivity of 91% and a specificity of 87%; this was significantly better than with TUUS (P < 0.01). CONCLUSION: The criterion of SLE on Gd-DTPA enhanced T1-weighted MRI using an endorectal surface coil is useful for staging bladder tumour, and the staging accuracy is significantly better than with TUUS.     

Initial clinical experience with real-time transrectal ultrasonography-magnetic resonance imaging fusion-guided prostate biopsy

OBJECTIVE

To evaluate the feasibility and utility of registration and fusion of real‐time transrectal ultrasonography (TRUS) and previously acquired magnetic resonance imaging (MRI) to guide prostate biopsies.

PATIENTS AND METHODS

Two National Cancer Institute trials allowed MRI‐guided (with or with no US fusion) prostate biopsies during placement of fiducial markers. Fiducial markers were used to guide patient set‐up for daily external beam radiation therapy. The eligible patients had biopsy‐confirmed prostate cancer that was visible on MRI. A high‐field (3T) MRI was performed with an endorectal coil in place. After moving to an US suite, the patient then underwent TRUS to visualize the prostate. The US transducer was equipped with a commercial needle guide and custom modified with two embedded miniature orthogonal five‐degrees of freedom sensors to enable spatial tracking and registration with MR images in six degrees of freedom. The MRI sequence of choice was registered manually to the US using custom software for real‐time navigation and feedback. The interface displayed the actual and projected needle pathways superimposed upon the real‐time US blended with the prior MR images, with position data updating in real time at 10 frames per second. The registered MRI information blended to the real‐time US was available to the physician who performed targeted biopsies of highly suspicious areas.

RESULTS

Five patients underwent limited focal biopsy and fiducial marker placement with real‐time TRUS‐MRI fusion. The Gleason scores at the time of enrolment on study were 8, 7, 9, 9, and 6. Of the 11 targeted biopsies, eight showed prostate cancer. Positive biopsies were found in all patients. The entire TRUS procedure, with fusion, took ≈10 min.

CONCLUSION

The fusion of real‐time TRUS and prior MR images of the prostate is feasible and enables MRI‐guided interventions (like prostate biopsy) outside of the MRI suite. The technique allows for navigation within dynamic contrast‐enhanced maps, or T2‐weighted or MR spectroscopy images. This technique is a rapid way to facilitate MRI‐guided prostate therapies such as external beam radiation therapy, brachytherapy, cryoablation, high‐intensity focused ultrasound ablation, or direct injection of agents, without the cost, throughput, or equipment compatibility issues that might arise with MRI‐guided interventions inside the MRI suite.     

Prostate MRI: Can we do without DCE sequences in 2013?

Multiparametric MRI (mp-MRI) of the prostate currently provides stable and reproducible performances. The usefulness of dynamic contrast-enhanced (DCE) sequences is currently challenged, as they sometimes only confirm what has already been observed on diffusion-weighted imaging (DWI) and require the additional purchase of a contrast agent. Eliminating these sequences may help accelerate the use of MRI in addition to, or in lieu of, prostate biopsies in selected patients. However, many studies show that these sequences can detect lesions invisible on T2-weighted and diffusion-weighted images, better assess cancer extension and aggressiveness, and finally help detecting recurrence after treatment. We present the various applications of dynamic MRI and discuss the possible consequences of its omission from the current protocol.     

Staging urinary bladder cancer with dynamic MR imaging

This article reviews the magnetic resonance (MR) staging of bladder cancer. The multiplanar and soft-tissue characterization capabilities of MR imaging make it a valuable diagnostic tool to image the urinary bladder. Recent advances of MR imaging such as fast imaging, pelvic phased array coil, and dynamic imaging improve the image quality and diagnostic accuracy for staging bladder cancer. Some patient-related factors are also important for optimal imaging of the urinary bladder, especially motion artifacts from the gastrointestinal tract and the degree of bladder distension. An anticholinergic agent should be used for suppressing the motion artifacts. Optimal bladder filling can be achieved by asking patients to void and drink water 1 hour before examinations. Scanning perpendicular to the bladder wall is necessary for optimal evaluation for staging bladder cancer. Oblique scanning is needed in cases when a tumor is not located on the dome, base, anterior wall, posterior wall, or lateral walls. The early phase image of dynamic imaging is most useful for staging tumors. Better contrast between tumor and bladder wall on dynamic images provides high staging accuracy, especially in differentiation between superficial tumors and tumors with muscle invasion. MR imaging is comparable to computed tomography (CT) in the evaluation of lymph nodes. Although MR imaging currently is not appropriate for screening for bladder cancer and detecting small tumors, it has been proved to be most useful in the staging of bladder cancer.     

Patient selection for magnetic resonance imaging of prostate cancer.

BACKGROUND: Routine magnetic resonance (MR) imaging for local staging of prostate cancer is controversial, due to moderate staging performance. However, MR imaging may be beneficial in a subgroup of patients with clinically localized prostate cancer. OBJECTIVE: To define the patient group in which local staging of prostate cancer using MR imaging is useful for treatment outcome. METHODS: We used a decision analytic model based on data found in the literature to define the patient subgroup which may benefit from local staging with MR imaging. We applied the threshold approach to calculate the threshold where direct surgery and surgery after MR imaging (surgery-MR imaging threshold) result in equal utility. Additionally, we calculated the threshold where direct radiation and radiation after MR imaging (MR imaging-radiotherapy threshold) result in equal utility. RESULTS: We found that the surgery-MR imaging threshold was at a probability of 45% of having stage > or =T(3) disease. The MR imaging-radiotherapy threshold was at a prior probability of 81% of having stage > or =T(3) disease. CONCLUSIONS: The application of the threshold approach indicated that MR imaging should be limited to patients with an intermediate-high risk of having stage T(3) disease.