Marc R. Engelbrecht

Local staging of prostate cancer using magnetic resonance imaging: a meta-analysis

Abstract. Our objective was to determine the influence of patient-, study design-, and imaging protocol characteristics on staging performance of MR imaging in prostate cancer. In an electronic literature search and review of bibliographies (January 1984 to May 2000) the articles selected included data on sensitivity and specificity for local staging. Subgroup analyses examined the influence of age, prostate specific antigen, tumor grade, hormonal pre-treatment, stage distribution, publication year, department of origin, verification bias, time between biopsy and MR imaging; consensus reading, study design, consecutive patients, sample size, histology preparation, imaging planes, fast spin echo, fat suppression, endorectal coil, field strength, resolution, glucagon, contrast agents, MR spectroscopy, and dynamic contrast-enhanced MRI. Seventy-one articles and five abstracts were included, yielding 146 studies. Missing values were highly prevalent for patient characteristics and study design. Publication year, sample size, histologic gold standard, number of imaging planes, turbo spin echo, endorectal coil, and contrast agents influenced staging performance (p=0.05). Due to poor reporting it was not possible to fully explain the heterogeneity of performance presented in the literature. Our results suggest that turbo spin echo, endorectal coil, and multiple imaging planes improve staging performance. Studies with small sample sizes may result in higher staging performance.

Prostate cancer: comparison of local staging accuracy of pelvic phased-array coil alone versus integrated endorectal-pelvic phased-array coils. Local staging accuracy of prostate cancer using endorectal coil MR imaging.

To compare the visibility of anatomical details and prostate cancer local staging performance of pelvic phased-array coil and integrated endorectal–pelvic phased-array coil MR imaging, with histologic analysis serving as the reference standard. MR imaging was performed in 81 consecutive patients with biopsy-proved prostate cancer, prior to radical prostatectomy, on a 1.5T scanner. T2-weighted fast spin echo images of the prostate were obtained using phased-array coil and endorectal–pelvic phased-array coils. Prospectively, one radiologist, retrospectively, two radiologists and two less experienced radiologists working in consensus, evaluated and scored all endorectal–pelvic phased-array imaging, with regard to visibility of anatomical details and local staging. Receiver operator characteristics (ROC) analysis was performed. Anatomical details of the overall prostate were significantly better evaluated using the endorectal–pelvic phased-array coil setup (P<0.05). The overall local staging accuracy, sensitivity and specificity for the pelvic phased-array coil was 59% (48/81), 56% (20/36) and 62% (28/45), and for the endorectal-pelvic phased-array coils 83% (67/81), 64% (23/36) and 98% (44/45) respectively, for the prospective reader. Accuracy and specificity were significantly better with endorectal–pelvic phased-array coils (P<0.05). The overall staging accuracy, sensitivity and specificity for the retrospective readers were 78–79% (P<0.05), 56–58% and 96%, for the endorectal–pelvic phased-array coils. Area under the ROC curve (Az) was significantly higher for endorectal–pelvic phased-array coils (Az=0.74) compared to pelvic phased-array coil (Az=0.57), for the prospective reader. The use of endorectal–pelvic phased array coils resulted in significant improvement of anatomic details, extracapsular extension accuracy and specificity. Overstaging is reduced significantly with equal sensitivity when an endorectal–pelvic phased-array coil is used.

Combined quantitative dynamic contrast-enhanced MR imaging and (1)H MR spectroscopic imaging of human prostate cancer.

To differentiate prostate carcinoma from healthy peripheral zone and central gland using quantitative dynamic contrast‐enhanced (DCE) magnetic resonance (MR) imaging and two‐dimensional 1H MR spectroscopic imaging (MRSI) combined into one clinical protocol.

Fast dynamic gadolinium‐enhanced MR imaging of urinary bladder and prostate cancer

Among the noninvasive imaging modalities, contrast enhanced magnetic resonance (MR) imaging is the most powerful tool with which to visualize vascularity. Common pathology only shows microvessel density, whereas dynamic MR imaging is sensitive to the total endothelial surface area of perfused vessels. Therefore, dynamic MR imaging may be of additional value in tumor staging and in evaluating therapies that affect the perfused microvessel density or surface area, such as chemo‐, radiation, or anti‐angiogenic therapy. In urinary bladder cancer, this technique results in improved local and nodal staging, in improved separation of transurethral granulation tissue and edema from malignant tumor, and in improved evaluation of the effect of chemotherapy. In prostate cancer, dynamic MR imaging may be of help in problematic cases. This technique can assist in determining seminal vesicle infiltration, in depicting of minimal capsular penetration, and in recognizing tumors within the transitional zone. Also, based on very rapid enhancement, very poorly differentiated tumors can be recognized. Evaluation of the effects of therapy is another promising area, however a lot of research remain to be done. This article reviews some basics of fast enhancement techniques, provides practical information, and shows recent developments, in using these fast techniques for staging and grading of bladder and prostate cancer, and for evaluating the effect of therapy. J. Magn. Reson. Imaging 1999;10:295–304.

Accurate estimation of pharmacokinetic contrast‐enhanced dynamic MRI parameters of the prostate

Quantitative analysis of contrast‐enhanced dynamic MR images has potential for diagnosing prostate cancer. Contemporary fast acquisition techniques can give sufficiently high temporal resolution to sample the fast dynamics observed in the prostate. Data reduction for parametric visualization requires automatic curve fitting to a pharmacokinetic model, which to date has been performed using least‐squares error minimization methods. We observed that these methods often produce unexpectedly noisy estimates, especially for the typically fast, intermediate parameters time‐to‐peak and start‐of‐enhancement, resulting in inaccurate pharmacokinetic parameter estimates. We developed a new curve fit method that focuses on the most probable slope. A set of 10 patients annotated using histopathology was used to compare the conventional and new methods. The results show that our new method is significantly more accurate, especially in the relatively less‐enhancing periferal zone. We conclude that estimation accuracy depends on the curve fit method, which is especially important when evaluating the periferal zone of the prostate. J. Magn. Reson. Imaging 2001;13:607–614.

MR imaging of the male pelvis

Abstract. Prostate and urinary bladder cancer are the most frequently encountered malignancies of the urinary tract. Appropriate use of the different imaging techniques is crucial for accurate assessment of prognosis and for the development of appropriate treatment planning. Especially determination of local tumor extension and detection of nodal or bone metastases is extremely important. In this regard MR imaging is the most promising imaging technique. Therefore, in this review its role in staging these malignancies is evaluated and compared with clinical staging, and other imaging techniques. Finally, future developments, such as new sequences, new contrast agents, the role of surface coils and MR-guided biopsy, are considered. Also, the preferred radiological approach is discussed.

Prostate cancer staging using imaging.

The prostate continues to be the commonest site of male cancer; for example, there were 184 500 new cases in the USA in 1998, accounting for 29% of new cancer cases in American men [1]. It has been estimated that 39 200 men in the USA died from prostate cancer in 1998. These estimates make prostate cancer the second cause of cancer-related death in men [2,3] and the probability of developing prostate cancer from birth to death is 20% [3]. Treatment selection depends on patient age and health, cancer stage and grade, morbidity and mortality of treatment, together with the preference of the patient and the physician. The mainstay of treatment for organ-con®ned disease is either radical surgery or curative radiotherapy [4,5]. These are only considered to be options if there is no spread to the seminal vesicles (seminal vesicle invasion, SVI), extension through the prostatic capsule (extracapsular extension, ECE) or metastatic disease (TNM stage fT2N0M0). Therefore, the purpose of staging is to detect extraprostatic disease. Clinical staging by DRE and PSA level are relatively inaccurate, and imaging techniques such as TRUS and MRI can be used to increase the accuracy of staging. This review deals with the current possibilities and limitations of imaging in the staging of prostate cancer.

Value of blood pool contrast agents in magnetic resonance angiography of the pelvis and lower extremities

Abstract. Our objective was: (1) to determine the appropriate dose of new ultrasmall superparamagnetic iron oxide particles for magnetic resonance angiography (MRA). This agent comprised of a single iron oxide crystal stabilized with a carbohydrate-polyethylene glycol coat (PEG-Ferron/NC 100150 injection); (2) to determine the proper flip angle for PEG-Ferron-enhanced 3 D time-of-flight (TOF) MRA sequence; and (3) to compare the enhancement of peripheral vessels following PEG-Ferron and GdDTPA-BMA. MRA parameters were: TR/TE = 50/2.1 ms, NEX = 1, FOV = 30 × 30 × 1.8 cm, and matrix = 256 × 128 × 64. In anesthetized beagle dogs (n = 10), the effects of PEG-Ferron and GdDTPA-BMA on regional signal were monitored for 45 min and compared. The lowest dose of PEG-Ferron (0.05 mmol/kg) produced the best enhancement of primary, secondary and tertiary vessels. The flip angle 60 ° provided better enhancement than 20 ° on contrast enhanced images. Unlike GdDTPA-BMA, PEG-Ferron allowed prolonged delineation (> 45 min) of the pelvis and lower extremities circulation. PEG-Ferron provided greater Contrast-to-noise ratio CNR (80.2 ± 6.2, P < 0.05) than GdDTPA-BMA (63.5 ± 2.5). It may be possible for blood pool contrast-enhanced 3 D TOF MRA to provide valuable information for visualization of vascular tree including guiding interventions.

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 ≧T3 disease. The MR imaging–radiotherapy threshold was at a prior probability of 81% of having stage ≧T3 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 T3 disease.

The value of single-shot black-blood MR imaging for mapping of the coronary arteries: a comparison of four different orientations during breath-holding and free breathing

The value of ECG-gated single-shot black-blood MR imaging for rapid visualization of the origin and course of the coronary arteries was investigated. The study population included 28 patients with known or suspected cardiac disease. ECG-gated single-shot black-blood MR acquisitions were acquired in the transverse, coronal, sagittal and LAO orientations, during free breathing and breath-holding. The origin of the left coronary artery was most frequently visualized in the coronal and LAO orientations and the origin of the right coronary artery was most frequently visualized in the LAO orientation. Overall, no significant difference was found for the visualization of the coronary artery segments and the overall image quality among acquisitions during breath-holding and free breathing. ECG-gated single-shot black-blood MR imaging (HASTE) appears to be a time-efficient and robust method for mapping of the entire coronary artery tree, without the need for breath-holding. The LAO orientation provides the most consistent visualization of the origins and major coronary artery segments.