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Genitourinary Imaging |
1 From the Departments of Radiology (M.R.E., H.J.H., G.J.J., J.G.B., J.O.B.), Epidemiology and Biostatistics (R.J.F.L.), Pathology (G.J.L.H.v.L., C.A.H.V.D.K.), and Urology (J.J.M.C.H.d.l.R.), University Medical Center Nijmegen, PO Box 9101, NL 6500 HB, Nijmegen, the Netherlands. From the 2001 RSNA scientific assembly. Received March 10, 2002; revision requested May 8; final revision received January 21, 2003; accepted February 21. Supported by the Dutch Cancer Society. Address correspondence to M.R.E. (e-mail: m.engelbrecht@rad.umcn.nl).
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODS RESULTS DISCUSSIONREFERENCES |
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MATERIALS AND METHODS: Of 58 patients with prostatic carcinoma, 36 were included for analysis. Patients underwent MR imaging at 1.5 T with an endorectal-pelvic phased-array coil and subsequently underwent prostatectomy. A T2-weighted turbo spin-echo sequence, an intermediate-weighted sequence, and a fast T1-weighted gradient-echo sequence (seven sections in 2.03 seconds) during bolus injection of 0.1 mmol gadopentetate dimeglumine per kilogram of body weight were performed. Contrast agent concentration–time curves were obtained for prostatic carcinoma and normal PZ and CG tissue by using whole-mount sections to guide placement of regions of interest. Onset time, time to peak, peak enhancement, relative peak enhancement, washout, and T2 relaxation rates were calculated. Multivariate receiver operating characteristic analysis was performed with and without relative peak enhancement.
RESULTS: Results of multivariate receiver operating characteristic analysis showed that relative peak enhancement demonstrated the highest area under the receiver operating characteristic curve (AUC) in the PZ and the CG (AUC = 0.93, 0.82). Results of multivariate analysis without relative peak enhancement showed that relative peak enhancement in the PZ and washout in the CG demonstrated the highest AUC (AUC = 0.9, 0.81). Pearson correlation coefficients between the dynamic parameters or T2 relaxation rates in carcinoma and the tumor stage, Gleason score, patient age, and tumor markers ranged between 0.02 and 0.44.
CONCLUSION: The optimal parameter for discrimination of prostatic carcinoma in the PZ and CG was relative peak enhancement. If relative peak enhancement was not used, then peak enhancement was optimal in the PZ, and washout was optimal in the CG. Poor-to-moderate correlation was present between the dynamic parameters or T2 relaxation rate in carcinoma and the tumor stage, Gleason score, patient age, tumor volume, and prostate-specific antigen.
© RSNA, 2003
Index terms: Magnetic resonance (MR), tissue characterization • Prostate neoplasms, MR, 844.32, 844.121411
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTS DISCUSSIONREFERENCES |
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MATERIALS AND METHODS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTS DISCUSSIONREFERENCES |
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This study received institutional approval by the local ethical committee, and informed consent was obtained from all patients prior to MR imaging. After imaging, all patients underwent radical retropubic prostatectomy. Patients who received neoadjuvant hormonal treatment before surgery were excluded from this study. The mean age of the 58 patients was 62.3 years (age range, 46–71 years). The mean level of prostate-specific antigen (PSA) was 12.9 ng/mL (range, 1.8–60 ng/mL). All patients had a clinical stage less than or equal to T2N0M0.
Imaging Examinations
MR imaging was performed at 1.5 T (Magnetom Vision; Siemens Medical Systems, Erlangen, Germany) by using the integrated endorectal-pelvic phased-array coil (MRInnervu; Medrad, Pittsburgh, Pa). The endorectal coil was inserted with the patient in the lateral decubitus position and was inflated with 50–100 mL of air. Peristalsis was suppressed by means of intramuscular administration of 1 mg of glucagon (Glucagen; Novo Nordisk A/S, Gentofte, Denmark). First, a sagittal T1-weighted localizing image was obtained to confirm coil positioning and to select locations for the transverse images. Transverse, sagittal, and coronal T2-weighted fast spin-echo images (4,000–4,400/132 [repetition time msec/echo time msec], echo train length of 15, two signals acquired, 180° flip angle, and 11 sections) were acquired. All examinations were performed by using a 4- or 5-mm section thickness with a 0.5-mm intersection gap, a 265–280-mm field of view, and a 180–240 x 512 matrix. The phase-encoding gradient was from left to right in order to decrease motion artifacts in the prostate. We subsequently acquired seven transverse sections covering the prostate from apex to base, as well as the seminal vesicles, by using a two-dimensional fast low-angle shot intermediate-weighted sequence (200/4.4) with an 8° flip angle, a 160 x 256 matrix, a 280–320-mm field of view, and a 5–7-mm section thickness with a 0.5–0.7-mm intersection gap. Thereafter, an intravenous bolus injection of 0.1 mmol gadopentetate dimeglumine (Magnevist; Schering, Berlin, Germany) per kilogram of body weight was administered by using a power injector (Spectris MR injection system; Medrad, Pittsburgh, Pa) with an injection speed of 2.5 mL/sec, which was followed by a 20-mL saline flush. We used a short bolus injection of 2.5 mL/sec instead of a long bolus injection because this would result in less noise-related error in the estimate of the various dynamic parameters (13).
During contrast material administration, a T1-weighted two-dimensional fast low-angle shot sequence (50/4.4) with a 60° flip angle, a 160 x 256 matrix, a 280–320-mm field of view, a 5–7-mm section thickness, a 0.5–0.7-mm intersection gap, and a time resolution of seven sections per 2.03 seconds for a total of 90–120 seconds was applied at the same section position as the intermediate-weighted sequence.
All images were transferred to an independent workstation (Ultrasparc 2; Sun Microsystems, Mountain View, Calif). Software was used to analyze and display contrast-enhanced dynamic MR imaging datasets (14). Contrast agent concentration–time curves were calculated with computer by using intermediate-weighted images as a calibration method (15).
The advantage of using concentration-time (16) curves instead of signal intensity–time curves is that variations in enhancement that are caused by differences in focal intermediate-weighted imaging and coil profile are corrected (17). Our method estimates the actual contrast agent concentration in a voxel up to a scaling constant c. This constant is the same for all patients measured on the same MR imager and includes factors such as T1 and T2 relaxivity, effective voxel dimensions, receiver gain, image scaling factors, repetition time, echo time, flip angle, calibration, and other manufacturer-specific constants. After calibration, a four-parameter model—onset time, time to peak, peak enhancement, and washout—was fitted to the concentration-time curves (14). The resulting parametric images were color-coded and integrated with T2-weighted images. T2 relaxation rate (in milliseconds) of a voxel was estimated by inserting the interpolated estimated T1, the interpolated intermediate-weighted value, and the acquisition parameters into the MR signal function of the T2-weighted turbo fast low-angle shot sequence that was used.
Histologic Examination
The examiners who performed histologic evaluation (C.A.H.V.D.K., G.J.L.H.v.L.) were blinded to the imaging results. Prostatectomy specimens were fixed overnight in a solution of 10% neutral buffered formalin. Whole-mount sections were made at 4-mm intervals perpendicular to the dorsal side of the prostate, corresponding to section orientations on MR images. After separating the step-sections into right and left halves, all sections were routinely embedded in paraffin. Tissue sections of 4-µm thickness were stained with hematoxylin-eosin. Regions representing carcinoma were outlined on the glass cover slips and were retraced onto a schematic overview of all prostate slices, extending from the base to the apex of the prostate. From these overviews, topographic relationships between multifocal tumors were evaluated. Multifocality of carcinoma was defined as a minimum spatial distance of 4 mm between any two malignant foci in any direction. The volumes of all independent carcinomas were calculated (by C.A.H.V.D.K. or G.J.L.H.v.L.) as the sum of surface areas for a given carcinoma multiplied by the slice thickness. Volumes were expressed in cubic centimeters. All carcinomas were evaluated for any extension into the adjacent zone (ie, PZ or CG) by one of the authors (M.R.E.) by retrospective evaluation of the histologic tumor maps.
Image Analysis
Whole-mount section histologic tumor maps were then used to localize carcinoma and normal tissue on fused T2-weighted parametric images. Only carcinomas greater than or equal to 0.5 cm3 were included for analysis, because we considered malignant lesions less than 0.5 cm3 to be beyond the limits of reliable correlation between MR imaging and histopathologic examination. Additionally, patients were excluded in cases of severe motion artifacts and/or biopsy hemorrhage artifacts. If a patient was excluded because of biopsy artifacts, the interval between biopsy and MR imaging was recorded. On the fused T2-weighted and parametric images (onset time of enhancement, time to peak, peak enhancement, and washout), voxels were chosen by one author (M.R.E.) for carcinoma and for a normal PZ or CG (depending on the location of the malignancy); voxels were chosen in such a way that only those that showed the highest or maximum individual values for each parameter were selected. Thus, malignant neoplasms were characterized by a limited variable set of voxels. On average, 10 voxels (range, four to 32) were selected both in carcinoma and in normal PZ or CG tissue.
The CG corresponds primarily to the transition zone enlarged with benign prostatic hypertrophy, although there will be portions of the periurethral zone and the central zone involved (18). The transition zone is the site of origin of benign prostatic hypertrophy, and, therefore, it often comprises a much larger portion of the gland in older men (19).
The entire normal PZ or CG was sampled to get the highest or maximum value for the various dynamic parameters. However, it was sometimes difficult to find areas without cancer, because tumors were often markedly irregular and demonstrated fingerlike projections with ill-defined margins that spread across the whole prostate gland. In these cases, a careful comparison was performed between the MR image and the histopathologic slide in order to define areas that were free of cancer.
In the calculation of the onset time, the beginning of enhancement in the nearest large vessel (the external iliac artery) was taken in account. Therefore, the onset time is defined as the difference in time (in seconds) between the beginning of enhancement in this vessel and the beginning of enhancement in the tissue of interest.
To decrease interpatient variability, we normalized the peak enhancement by using normal PZ or CG tissue as a reference tissue. In this manner we introduced the relative peak enhancement, which is the peak enhancement in the carcinoma minus the average peak enhancement in the accompanying PZ or CG tissue. If the entire PZ or CG is infiltrated with carcinoma, it is not possible to normalize the peak enhancement by using normal PZ or CG tissue. In such a case, relative peak enhancement cannot be used. Therefore we analyzed our data with and without the use of relative peak enhancement.
The washout was calculated by using linear regression analysis of the curve in the postpeak area.
Statistical Analysis
Differences in onset time, time to peak, peak enhancement, relative peak enhancement, washout, and T2 relaxation rates between prostatic carcinoma and normal PZ or CG tissues were assessed with the two-tailed paired Student t test; a P value of .05 was required to denote significance. Area under the receiver operating characteristic curve (AUC) was calculated to assess which parameter was optimal for cancer discrimination in the PZ or CG. To assess interpatient variation for dynamic parameters, the mean values (± SD) per carcinoma site and corresponding normal tissues (PZ or CG) were calculated and plotted in graphs. Next, histologic slides were reviewed to explain possible interpatient variations.
To determine the additional discriminative value of each parameter, a stepwise logistic regression analysis (multivariate analysis) of the AUC was used. The multivariate analysis was performed as a backward-stepping procedure, with a P value of more than .05 required for exclusion. First, we performed multivariate analysis by using all dynamic and T2 relaxation parameters. Next, we performed multivariate analysis without relative peak enhancement.
The correlation between the dynamic parameters and T2 relaxation rate in carcinoma and the Gleason score, tumor volume, PSA, extracapsular extension (ECE), seminal vesicle invasion (SVI), and patient age were assessed by using the Pearson correlation coefficient. Additional multivariate regression analysis was performed to explore possible associations between Gleason score, tumor volume, PSA, ECE, SVI, patient age, dynamic parameters, and T2 relaxation rate. Next, receiver operating characteristic analysis was performed to determine the ability of dynamic parameters and T2 relaxation to predict Gleason score, cancer volume, PSA, SVI, ECE, and patient age.
In the receiver operating characteristic analysis, we included parameters that demonstrated significant correlation in the multivariate regression analysis and excluded parameters that were not known a priori (ie, before radical prostatectomy).
We analyzed all dynamic and T2 relaxation parameters according to single versus multiple neoplasms per prostate gland by using the Student t test.
All statistical analyses were performed by using Rockit 0.9B software (C. Metz, PhD; Department of Radiology, University of Chicago, Ill), SAS/STAT software (SAS Institute, Cary, NC), and Excel software with Windows 95 (Microsoft, Redmond, Wash).
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RESULTS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTS DISCUSSIONREFERENCES |
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The average age of the 36 patients in our study was 61.3 years (range, 49–72 years). The average level of PSA was 10.6 ng/mL (range, 4.5–38.0 ng/mL; in three patients, no PSA data were available). Sextant biopsies preceded MR imaging by an average (± SD) of 25 days ± 7 (range, 5–41 days). All patients underwent radical retropubic prostatectomy within 3 weeks after MR imaging. In the 36 patients, 55 separate malignant neoplasms were found: 32 carcinomas in the PZ and 23 carcinomas in the CG. The median Gleason score per carcinoma was 7 (range, 3–9). Of the 32 PZ carcinomas, 16 demonstrated extension into the CG. Of the 23 CG carcinomas, 12 extended into the PZ.
Dynamic and T2 Relaxation Rate Parameters
We measured 319 voxels in 32 malignant PZ sites and compared them with 319 voxels in 32 normal PZ sites. Carcinomatous PZ tissue showed earlier onset of enhancement and shorter time to peak compared with normal PZ tissue (P 
.001; Table 1). Peak enhancement and relative peak enhancement were increased in carcinomatous tissue compared with normal PZ tissue (P .001). On average, carcinomatous tissue demonstrated washout, whereas normal PZ tissue did not demonstrate washout (P .001). T2 relaxation rate was lower in malignant tissue compared with normal PZ tissue (P .001). Relative peak enhancement (AUC = 0.93) and peak enhancement (AUC = 0.89) demonstrated the highest AUC in the PZ (Table 1). Relative peak enhancement and peak enhancement increased the AUC compared with T2-weighted images significantly from 0.64 toward 0.93 and 0.89, respectively (P < .001). Multivariate analysis showed that relative peak enhancement would be the parameter with the highest yield in discriminatory performance (AUC = 0.94; 95% CI: 0.91, 0.97). If onset time, time to peak, T2 relaxation rate, and washout were added, discriminatory performance increased from AUC of 0.94 toward AUC of 0.96 (95% CI: 0.94, 0.97). If peak enhancement was used instead of relative peak enhancement, then multivariate analysis showed that the highest gain in discriminatory performance would be accomplished by using peak enhancement (AUC = 0.90; 95% CI: 0.87, 0.93). The addition of onset time, time to peak, T2 relaxation rate, and washout to peak enhancement increased AUC from 0.90 toward 0.94 (95% CI: 0.91, 0.97). Of the 32 malignant lesions located in the PZ, 31 demonstrated higher relative peak enhancement compared with normal PZ tissue (Figure, A). In one patient (arrowhead in Figure, A), a lower relative peak enhancement was demonstrated in carcinomatous tissue than in normal PZ tissue. In this patient, severe coexistent chronic active prostatitis was described at histopathologic examination as being throughout the gland. Although we used the PZ as a reference tissue, there were still variations in relative peak enhancement between various carcinomas (Figure, A).
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.001) (Table 1). Unlike results in the PZ, results in the CG showed no significant differences in T2 relaxation rates between cancerous and healthy tissue (P = .10). In the CG, relative peak enhancement (AUC = 0.83), peak enhancement (AUC = 0.79), and washout (AUC = 0.82) showed similar discriminatory performance (Table 1). The relative peak enhancement, peak enhancement, and washout increased AUC from 0.51 (T2 relaxation rate) toward 0.83, 0.79, and 0.82, respectively (Table 1; P < .001). Multivariate analysis showed that in the CG, relative peak enhancement would be the parameter with the highest yield in discriminatory performance (AUC = 0.82; 95% CI: 0.77, 0.87). If washout, time to peak, and onset time were added, discriminatory performance increased from AUC of 0.82 toward AUC of 0.89 (95% CI: 0.85, 0.93). If peak enhancement was used instead of relative peak enhancement, then multivariate analysis showed that the highest gain in discriminatory performance would be accomplished by using washout (AUC = 0.81; 95% CI: 0.76, 0.86). The addition of peak enhancement, time to peak, and onset time increased discriminatory performance from AUC of 0.81 toward 0.87 (95% CI: 0.82, 0.92). The measurements of relative peak enhancement for carcinomas located in the CG are shown in the Figure, B. In 21 carcinomas, relative peak enhancement was higher compared with normal CG tissue. However, in malignant lesions 5 and 12 (arrows in Figure, B), a lower relative peak enhancement in carcinoma was seen compared with normal CG tissue. No difference in histologic results was noted between these prostate glands and the others. Of the 23 malignancies in the CG, 16 demonstrated washout when compared with normal CG tissue. Washout showed one false-positive enhancement in the patient with carcinoma 12 (arrow in Figure, C). Histopathologic examination revealed no difference between the prostate in this patient and the prostates in other patients. In both the PZ and CG, poor-to-moderate correlation (ie, 0.02–0.44) was seen between the dynamic parameters or T2 relaxation rates in malignant prostatic neoplasms and the Gleason score, tumor volume, PSA, ECE, SVI, and patient age (Table 2). The highest correlations were seen in the CG between peak enhancement and PSA (r = 0.44) and between peak enhancement and ECE (r = 0.44). Multivariate regression analysis demonstrated that Gleason score, PSA, patient age, cancer volume, SVI, and ECE were significantly (P < .05) correlated with each other and with the dynamic and T2 relaxation parameters. The addition of dynamic and T2 relaxation parameters in the prediction of Gleason score, cancer volume, ECE, and SVI resulted in an AUC increase of 0.05. 0.07, 0.07, and 0.07, respectively. For patient age and PSA it was not possible to perform multivariate regression analysis without the addition of dynamic and T2 relaxation parameters, because there were no variables available. Addition of dynamic and T2 relaxation parameters resulted in an AUC of 0.66 for PSA and 0.56 for patient age.
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTS DISCUSSIONREFERENCES |
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Relative peak enhancement cannot be used if carcinoma has spread throughout the prostate because in such a case it is not possible to use normal prostatic tissue as a reference. In this case, peak enhancement can be used as the parameter in the PZ, and washout can be used as the parameter in the CG. Peak enhancement does not perform as well in the CG compared with the PZ because the difference in peak enhancement between carcinomatous tissue and normal CG tissue is smaller. This is caused by the higher peak enhancement of normal CG tissue. T2 relaxation rate performed poorly as a discriminating parameter in both the PZ and the CG. Individual dynamic parameters (except time to peak) showed higher discriminatory performance compared with T2 relaxation rate.
The difference in results between the study by Padhani et al (22) and our study is that we found a significant difference in onset time of enhancement between prostate cancer and normal PZ or CG tissue. According to our data, the difference in the start of enhancement between carcinoma and normal PZ or CG tissue is 2.7 seconds and 2.3 seconds, respectively. It is probable that the 9–10-second temporal resolution used by Padhani et al was too low to enable detection of these relatively small differences in onset time. Also, Padhani et al did not use whole-mount section histologic examination as a reference standard.
Turnbull et al (23) described substantial differences between carcinoma and (fibromuscular) benign prostatic hypertrophy in the amplitude of the initial upslope (comparable to time to peak). However, this study does not demonstrate differences using washout. To our knowledge, no reports thus far have been published on the discriminative performance of relative peak enhancement and peak enhancement. Washout has already been described as a useful dynamic feature (24,25) in the characterization of breast carcinoma lesions. Multivariate regression and receiver operating characteristic analysis demonstrated that use of dynamic parameters and T2 relaxation rate resulted in a marginal increase in the prediction of the Gleason score, cancer volume, PSA, ECE, SVI, and patient age.
The poor-to-moderate correlation between Gleason score, tumor volume, PSA, ECE, SVI, patient age, and dynamic or T2 relaxation parameters in carcinoma are in agreement with results of Padhani et al (22). Gossmann et al (26) demonstrated that when using macromolecular contrast media, dynamic MR imaging can provide some differentiation in histopathologic prostatic tumor grades in xenografts. In the same study a comparison was made between macromolecular and small-molecular contrast media. In accordance with our study, considerable overlap was found between the endothelial transfer coefficient (a measure for permeability) values for low- and high-grade tumor types by using small-molecular contrast media, although in that study (26) a temporal resolution of 30 seconds was used. Using a temporal resolution of 2.03 seconds, we demonstrated a similar poor-to-moderate correlation between Gleason score and dynamic enhancement in prostatic carcinoma. There was a coincidental finding of a false-positive enhancement in one case in the PZ using relative peak enhancement in concomitant severe prostatitis. The typical enhancement caused by prostatitis has been previously described with contrast-enhanced helical computed tomography (27).
A limitation of this study is that, because of selective sampling of voxels in the most enhancing part of the carcinoma, enhancement characteristics of other parts of the carcinoma were not evaluated. However, if an average region of interest had been used that included the entire carcinoma, then the heterogeneity of carcinoma enhancement would have been ignored. Also, when an unselective sampling protocol is used, the AUC for the various dynamic and T2 parameters may be different. Since the purpose of this study was to compare which dynamic and T2 relaxation rate parameters show the highest performance in carcinoma discrimination, we sampled the voxel values for each dynamic and T2 parameter in the carcinoma and in normal PZ and CG tissue in the same manner; therefore, the various parameters can be compared reliably with each other. Finally, in a similar study in which prostatic carcinoma enhancement was measured, a comparable selective sampling method was used (26).
Prostatic carcinomas smaller than 0.5 mL were excluded from our study. Therefore our results may be biased toward a higher discriminative performance, because larger carcinomas may be easier to discriminate. However, only prostate cancers of 0.5 cm3 or larger are considered clinically important (28).
We used a parametric description of concentration-time curves, while Tofts et al (29) proposed to also fit these curves to a physiologic model. However, the required arterial input function is difficult to estimate accurately. We encountered difficulties such as strong flow and saturation artifacts, noise, and interpatient variability due to differences in vasculature (eg, anatomy or atherosclerosis). According to Tofts et al (29), if a step-shaped arterial input function is assumed then our time to peak is directly related to the rate constant between the extravascular extracellular space and the blood plasma volume (permeability surface area), and peak enhancement is related to the volume of the extracellular space.
A further constraint of our study may be that the scaling factor in our contrast agent measurements did not allow comparison with other studies. The fact is that it is difficult to use robust calibration to obtain accurate absolute values. Developing a method that would allow operating under clinical conditions by using clinical MR machines and that would have reproducible machine independence requires extensive research, which is outside the scope of this study.
A remaining limitation of dynamic MR imaging in the prostate is susceptibility to motion and biopsy artifacts (30), as can be seen by the fact that more than one-third of our patient population (22 of 58 patients) had images that could not be interpreted at all because of severe motion artifacts and/or postsurgical artifacts.
A major limitation in the use of relative peak enhancement as a parameter is that it can never be used in a prospective manner, because one never knows a priori where the carcinoma is located. Therefore it will not be possible to normalize the peak enhancement by using normal PZ tissue. In clinical practice, peak enhancement and washout will be the optimal dynamic parameters.
The purpose of this study was to find new dynamic parameters that could be used in the interpretation of prostate MR images. By using our proposed parameters of relative peak enhancement, peak enhancement, and washout, an efficient dynamic MR imaging reading protocol for prostate cancer can be developed. However, future studies should validate the discriminatory performance of the studied dynamic parameters in a prospective study, where enhancement is compared with whole-mount section histopathologic examination as the standard of reference.
In conclusion, the optimal parameter for discrimination of prostatic carcinoma in the PZ and CG is relative peak enhancement. If it is not possible to use relative peak enhancement, peak enhancement is the optimal parameter in the PZ and washout is the optimal parameter in the CG. Relative peak enhancement, peak enhancement, and washout all improve the ability to discriminate prostatic carcinoma in comparison with T2-weighted images. Poor-to-moderate correlation is present between dynamic parameters or T2 relaxation rate in prostatic carcinoma and tumor stage, histologic grade, patient age, tumor volume, and serum PSA.
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ACKNOWLEDGMENTS |
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FOOTNOTES |
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Author contributions: Guarantors of integrity of entire study, J.O.B., M.R.E., G.J.J.; study concepts and design, J.O.B., M.R.E., H.J.H., G.J.J.; literature research, M.R.E.; clinical studies, J.O.B., M.R.E., G.J.L.H.v.L., C.A.H.V.D.K., J.J.M.C.H.d.l.R.; experimental studies, J.O.B., H.J.H.; data acquisition, J.O.B., M.R.E., G.J.L.H.v.L., C.A.H.V.D.K.; data analysis/interpretation, all authors; statistical analysis, M.R.E., H.J.H., R.J.F.L.; manuscript preparation and definition of intellectual content, all authors; manuscript editing, J.O.B., J.G.B., M.R.E., H.J.H., G.J.J.; manuscript revision/review and final version approval, all authors
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTS DISCUSSIONREFERENCES |
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H. J. Huisman, J. J. Futterer, E. N. J. T. van Lin, A. Welmers, T. W. J. Scheenen, J. A. van Dalen, A. G. Visser, J. A. Witjes, and J. O. Barentsz Prostate Cancer: Precision of Integrating Functional MR Imaging with Radiation Therapy Treatment by Using Fiducial Gold Markers Radiology, July 1, 2005; 236(1): 311 - 317. [Abstract] [Full Text] [PDF]
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D. Beyersdorff, A. Winkel, B. Hamm, S. Lenk, S. A. Loening, and M. Taupitz MR Imaging-guided Prostate Biopsy with a Closed MR Unit at 1.5 T: Initial Results Radiology, February 1, 2005; 234(2): 576 - 581. [Abstract] [Full Text] [PDF]
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D. L. Buckley, C. Roberts, G. J. M. Parker, J. P. Logue, and C. E. Hutchinson Prostate Cancer: Evaluation of Vascular Characteristics with Dynamic Contrast-enhanced T1-weighted MR Imaging--Initial Experience Radiology, December 1, 2004; 233(3): 709 - 715. [Abstract] [Full Text] [PDF]
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F. G. Claus, H. Hricak, and R. R. Hattery Pretreatment Evaluation of Prostate Cancer: Role of MR Imaging and 1H MR Spectroscopy RadioGraphics, October 1, 2004; 24(suppl_1): S167 - S180. [Abstract] [Full Text] [PDF]
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R. V. Mulkern, F. J. Rybicki, S. J. Haker, C. M. C. Tempany, M. R. Engelbrecht, H. J. Huisman, G. J. Jager, and J. O. Barentsz Comments on T2 Measurements of Prostate Tissue * Dr Engelbrecht and colleagues respond: Radiology, August 1, 2004; 232(2): 624 - 626. [Full Text] [PDF]
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 W. V. Vogel, W. J.G. Oyen, J. O. Barentsz, J. H.A.M. Kaanders, and F. H.M. Corstens PET/CT: Panacea, Redundancy, or Something in Between? J. Nucl. Med., January 1, 2004; 45(90010): 15S - 24. [Abstract] [Full Text] [PDF]
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) compared with normal tissue (
) in the prostate. Each carcinoma site is represented as a separate case. c = scaling factor, mmol Gd-DTPA/kg = mmol/kg gadopentetate dimeglumine. A, Relative peak enhancement in the PZ (32 separate carcinoma sites). Carcinoma demonstrates a higher relative peak enhancement than does normal tissue. One carcinoma site (arrowhead) demonstrates a lower relative peak enhancement than does normal tissue. In this case, severe coexistent chronic active prostatitis was present throughout the prostate. Interpatient variation is present (eg, carcinoma sites 2 versus 32 [arrows]). B, Relative peak enhancement in the CG (23 separate carcinoma sites). In general, carcinoma demonstrates a higher relative peak enhancement than does normal tissue. Carcinoma sites 5 and 12 (arrows) demonstrate a lower relative peak enhancement than does normal tissue. No histologic differences were noted between the prostate glands of these patients (sites 5 and 12) and those of other patients. C, Washout in the CG (23 separate carcinoma sites). In general, carcinoma demonstrates washout, whereas normal tissue does not. Carcinoma site 12 (arrow) shows false-positive washout. No histologic differences were noted between the prostate gland of this patient and the prostate glands of other patients.