Imaging clinically localized prostate cancer

Diagnostic Value of CT in Detecting Peripheral Zone Prostate Cancer

OBJECTIVE. The purpose of this study was to identify the sensitivity of contrast-enhanced CT in detecting high-grade prostate adenocarcinoma. MATERIALS AND METHODS. A retrospective analysis included 100 patients with prostate cancer proven by biopsy between January 2010 and December 2017 who underwent staging CT of the abdomen and pelvis within 3 months of diagnosis. The control subjects were 100 randomly selected aged-matched male outpatients with no known history of malignancy who underwent contrast-enhanced CT of the abdomen and pelvis in the same time period as the patients with cancer. Two readers, blinded to both groups, independently assessed the likelihood of prostate cancer on the basis of the CT finding of focal abnormally increased peripheral enhancement in the prostate. Binary classification of sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) was used to assess the diagnostic utility of CT versus the reference standard of transrectal ultrasound-guided biopsy. RESULTS. Eighty-three of 100 patients with biopsy-proven prostate cancer and 92 of 100 control subjects were correctly identified (sensitivity, 0.83; specificity, 0.92; PPV, 0.91; NPV, 0.84). There was no significant difference in diagnostic accuracy among subjects with different Gleason scores. Interrater agreement on both the cancer and control patients was 0.76 as assessed by Cohen kappa statistic. CONCLUSION. Incidental detection of a focal area of increased enhancement in the periphery of the prostate at contrast-enhanced CT may represent a clinically significant cancer and deserves further workup with prostate-specific antigen measurement and correlation with clinical risk factors for prostate cancer.

The Use of Magnetic Resonance Imaging in the Prostate Cancer Primary Diagnostic Pathway: Is It Ready for Primetime?

Multiparametric magnetic resonance imaging (mpMRI) has been increasingly utilized in the prostate cancer diagnostic landscape over the last five years. The majority of the literature has focused on its use in men with a previous negative biopsy. However, over time, clinicians have begun using mpMRI in the work-up of men being considered for primary biopsy and subsequently data characterizing its diagnostic performance in this setting is emerging. This review comprehensively assesses the utility of mpMRI in the primary biopsy setting.

The Use of Magnetic Resonance Imaging in the Prostate Cancer Primary Diagnostic Pathway: Is It Ready for Primetime?

Multiparametric magnetic resonance imaging (mpMRI) has been increasingly utilized in the prostate cancer diagnostic landscape over the last five years. The majority of the literature has focused on its use in men with a previous negative biopsy. However, over time, clinicians have begun using mpMRI in the work-up of men being considered for primary biopsy and subsequently data characterizing its diagnostic performance in this setting is emerging. This review comprehensively assesses the utility of mpMRI in the primary biopsy setting.

[Imaging of locally advanced prostate cancer : Importance of ultrasound and especially MRI]

Prostate cancer is the most common male malignant tumor in Germany, which thus places growing demands on differentiated imaging and risk-adapted therapeutic approaches. Multiparametric MRI (mpMRI) of the prostate enables reliable detection of clinically significant cancers and is currently the leading imaging modality for the detection, characterization, and local staging of prostate cancer. According to the German S3 guideline, mpMRI of the prostate is currently primarily recommended in patients with previous negative TRUS biopsies and persisting tumor suspicion. The serial use of mpMRI in the pretherapeutic setting can support individual therapy planning of patients with locally advanced prostate cancer in the near future.

Newer Imaging Modalities to Assess Tumor in the Prostate

Background

Several advances in the imaging of prostate cancer have been made in recent years. Diagnostic staging has become increasingly complex and confusing as newer technologies have developed more rapidly than research has been able to confirm or refute the accuracy of these technologies. By the time research has been performed, the technology used for a study has often become outdated and newer and more sophisticated imaging has become available.

Methods

We reviewed the literature on local and nodal staging of prostate cancer, as well as the role of magnetic resonance imaging (MRI), magnetic resonance spectroscopic imaging (MRSI), dynamic contrast-enhanced MRI, positron emission tomography (PET), endorectal power Doppler, lymphotropic MRI contrast agents, and future possibilities such as diffusion MRI. This review is not systematic, but rather focused on these imaging modalities.

Results

Advances in MRI, ultrasound, and lymphotropic contrast agents have improved our ability to differentiate between T2 and T3 prostate tumors. PET imaging has proven less successful at staging prostate cancer. A literature review suggests patients with moderate risk of extracapsular extension benefit most from endorectal MRI evaluation. Spectroscopy, dynamic imaging, and lymphotropic contrast agents are expected to continue to improve sensitivity and specificity of staging of prostate cancer. Power Doppler evaluation with endorectal ultrasound has proved useful for evaluation during endorectal biopsy for identifying hypervascular tumors for directed biopsy. Diffusion-weighted MRI remains untested clinically and represents a future direction for research.

Conclusions

Future studies using these new techniques are needed to demonstrate changes in outcomes in large patient populations.

Diagnosis of prostate cancer using anti-PSMA aptamer A10-3.2-oriented lipid nanobubbles

In this study, the lipid targeted nanobubble carrying the A10-3.2 aptamer against prostate specific membrane antigen was fabricated, and its effect in the ultrasound imaging of prostate cancer was investigated. Materials including 2-dipalmitoyl-sn-glycero-3-phosphocholine, 1,2-dipalmitoyl-sn-glycero-3-phosphatidic acid, 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine, 1,2-dipalmitoyl-sn-glycero-3-phosphoglycerol, carboxyl-modified 1,2-distearoyl-sn-glycero-3-phosphoethanolamine, and polyethyleneglycol-2000 were for mechanical oscillation, and nanobubbles were obtained through the centrifugal flotation method. After mice were injected with nanobubbles, abdominal color Doppler blood flow imaging significantly improved. Through left ventricular perfusion with normal saline to empty the circulating nanobubbles, nanobubbles still existed in tumor tissue sections, which demonstrated that nanobubbles could enter tissue spaces via the permeability and retention effect. Fluorinated A10-3.2 aptamers obtained by chemical synthesis had good specificity for PSMA-positive cells, and were linked with carboxyl-modified 1,2-distearoyl-sn-glycero-3-phosphoethanolamine lipid molecules from the outer shell of nanobubbles via amide reaction to construct targeted nanobubbles. Gel electrophoresis and immunofluorescence confirmed that targeted nanobubbles were fabricated successfully. Next, targeted nanobubbles could bind with PSMA-positive cells (C4-2 cells), while not with PSMA-negative cells (PC-3 cells), using in vitro binding experiments and flow cytometry at the cellular level. Finally, C4-2 and PC-3 xenografts in mice were used to observe changes in parameters of targeted and non-targeted nanobubbles in the contrast-enhanced ultrasound mode, and the distribution of Cy5.5-labeled targeted nanobubbles in fluorescent imaging of live small animals. Comparison of ultrasound indicators between targeted and non-targeted nanobubbles in C4-2 xenografts showed that they had similar peak times (P>0.05), while the peak intensity, half time of peak intensity, and area under the curve of ½ peak intensity were significantly different (P<0.05). In PC-3 xenografts, there were no differences in these four indicators. Fluorescent imaging indicated that targeted nanobubbles had an aggregation ability in C4-2 xenograft tumors. In conclusion, targeted nanobubbles carrying the anti-PSMA A10-3.2 aptamer have a targeted imaging effect in prostate cancer.

PET Imaging of Prostate Cancer Using Radiolabeled Choline

Although PET using fludeoxyglucose F 18 (FDG) is a promising modality for metabolic imaging of different tumors, the results in prostate cancer have been somewhat inconsistent. Low FDG avidity of most prostate cancer cells and urinary activity are suggested as the main limitations of FDG PET for the evaluation of prostate cancer. Prostate cancer exhibits increased choline metabolism, which is the rationale for using radiolabeled choline for PET. This article describes the basic concepts of radiolabeled choline regarding pharmacokinetics, radiation dosimetry, synthesis, and biodistribution, in addition to advances concerning clinical PET using 11C- and 18F-choline in primary staging and restaging of prostate cancer patients.

Mass-like peripheral zone enhancement on CT is predictive of higher-grade (Gleason 4 + 3 and higher) prostate cancer

PURPOSE

To determine whether focal peripheral zone enhancement on routine venous-phase CT is predictive of higher-grade (Gleason 4 + 3 and higher) prostate cancer.

MATERIALS AND METHODS

IRB approval was obtained and informed consent waived for this HIPAA-compliant retrospective study. Forty-three patients with higher-grade prostate cancer (≥Gleason 4 + 3) and 96 with histology-confirmed lower-grade (≤Gleason 3 + 4 [n = 47]) or absent (n = 49) prostate cancer imaged with venous-phase CT comprised the study population. CT images were reviewed by ten blinded radiologists (5 attendings, 5 residents) who scored peripheral zone enhancement on a scale of 1 (benign) to 5 (malignant). Mass-like peripheral zone enhancement was considered malignant. Likelihood ratios (LR) and specificities were calculated. Multivariate conditional logistic regression analyses were conducted.

RESULTS

Scores of "5" were strongly predictive of higher-grade prostate cancer (pooled LR+ 9.6 [95% CI 5.8-15.8]) with rare false positives (pooled specificity: 0.98 [942/960, 95% CI 0.98-0.99]; all 10 readers had specificity ≥95%). Attending scores of "5" were more predictive than resident scores of "5" (LR+: 14.7 [95% CI 5.8-37.2] vs. 7.6 [95% CI 4.2-13.7]) with similar specificity (0.99 [475/480, 95% CI 0.98-1.00] vs. 0.97 [467/480, 95% CI 0.96-0.99]). Significant predictors of an assigned score of "5" included presence of a peripheral zone mass (p < 0.0001), larger size (p < 0.0001), and less reader experience (p = 0.0008). Significant predictors of higher-grade prostate cancer included presence of a peripheral zone mass (p = 0.0002) and larger size (p < 0.0001).

CONCLUSION

Focal mass-like peripheral zone enhancement on routine venous-phase CT is specific and predictive of higher-grade (Gleason 4 + 3 and higher) prostate cancer.

Dual Processing Model for Medical Decision-Making: An Extension to Diagnostic Testing

Dual Processing Theories (DPT) assume that human cognition is governed by two distinct types of processes typically referred to as type 1 (intuitive) and type 2 (deliberative). Based on DPT we have derived a Dual Processing Model (DPM) to describe and explain therapeutic medical decision-making. The DPM model indicates that doctors decide to treat when treatment benefits outweigh its harms, which occurs when the probability of the disease is greater than the so called "threshold probability" at which treatment benefits are equal to treatment harms. Here we extend our work to include a wider class of decision problems that involve diagnostic testing. We illustrate applicability of the proposed model in a typical clinical scenario considering the management of a patient with prostate cancer. To that end, we calculate and compare two types of decision-thresholds: one that adheres to expected utility theory (EUT) and the second according to DPM. Our results showed that the decisions to administer a diagnostic test could be better explained using the DPM threshold. This is because such decisions depend on objective evidence of test/treatment benefits and harms as well as type 1 cognition of benefits and harms, which are not considered under EUT. Given that type 1 processes are unique to each decision-maker, this means that the DPM threshold will vary among different individuals. We also showed that when type 1 processes exclusively dominate decisions, ordering a diagnostic test does not affect a decision; the decision is based on the assessment of benefits and harms of treatment. These findings could explain variations in the treatment and diagnostic patterns documented in today's clinical practice.

Usefulness of diffusion-weighted magnetic resonance imaging in the diagnosis of prostate cancer

RATIONALE AND OBJECTIVES

The aim of this study was to evaluate the diagnostic accuracy of diffusion-weighted magnetic resonance imaging (DWI) in prostate cancer.

MATERIALS AND METHODS

The MEDLINE, Embase, CANCERLIT, and Cochrane Library databases were searched for studies published from January 2001 to August 2011 evaluating the diagnostic performance of DWI in detecting prostate carcinoma. Sensitivities and specificities were determined across studies, and summary receiver-operating characteristic curves were constructed using hierarchical regression models.

RESULTS

Sixteen studies (18 subsets) with a total of 852 patients were included. Six studies (seven subsets) examining men with pathologically confirmed prostate cancer (260 patients) had pooled sensitivity and specificity of 0.88 (95% confidence interval [CI], 0.76-0.95) and 0.84 (95% CI, 0.76-0.90), respectively. Compared to patients at high risk for clinically relevant cancer, sensitivity was higher in low-risk patients (0.94 [95% CI, 0.89-0.97] vs 0.62 [95% CI, 0.54-0.70], P < .05), but specificity was lower (0.86 [95% CI, 0.72-0.94] vs 0.89 [95% CI, 0.83-0.93], P < .05). Ten studies (11 subsets) examining patients with suspected prostate cancer (592 patients) had pooled sensitivity and specificity of 0.76 (95% CI, 0.68-0.84) and 0.86 (95% CI, 0.79-0.91). Sensitivity was lower in high-risk patients (0.74 [95% CI, 0.57-0.87] vs 0.78 [95% CI, 0.70-0.84], P > .05), but specificity was higher (0.92 [95% CI, 0.89-0.94] vs 0.78 [95% CI, 0.70-0.84], P < .05).

CONCLUSIONS

A limited number of small studies suggest that DWI could be a rule-in test for high-risk patients. Further prospective studies including larger populations are necessary to confirm the actual value of DWI in this field.

Applications of transrectal ultrasound in prostate cancer

Transrectal ultrasound (TRUS) was first developed in the 1970s. TRUS-guided biopsy, under local anaesthetic and prophylactic antibiotics, is now the most widely accepted method to diagnose prostate cancer. However, the sensitivity and specificity of greyscale TRUS in the detection of prostate cancer is low. Prostate cancer most commonly appears as a hypoechoic focal lesion in the peripheral zone on TRUS but the appearances are variable with considerable overlap with benign lesions. Because of the low accuracy of greyscale TRUS, TRUS-guided biopsies have become established in the acquisition of systematic biopsies from standard locations. The number of systematic biopsies has increased over the years, with 10-12 cores currently accepted as the minimum standard. This article describes the technique of TRUS and biopsy and its complications. Novel modalities including contrast-enhanced modes and elastography as well as fusion techniques for increasing the sensitivity of TRUS-guided prostate-targeted biopsies are discussed along with their role in the diagnosis and management of prostate cancer.

MR Imaging of Prostate Cancer: Diffusion Weighted Imaging and (3D) Hydrogen 1 (H) MR Spectroscopy in Comparison with Histology

Purpose. To evaluate retrospectively the impact of diffusion weighted imaging (DWI) and (3D) hydrogen 1 (¹H) MR-spectroscopy (MRS) on the detection of prostatic cancer in comparison to histological examinations. Materials and Methods: 50 patients with suspicion of prostate cancer underwent a MRI examination at a 1.5T scanner. The prostate was divided into sextants. Regions of interest were placed in each sextant to evaluate the apparent diffusion coefficient (ADC)-values. The results of the DWI as well as MRS were compared retrospectively with the findings of the histological examination. Sensitivity and specificity of ADC and metabolic ratio (MET)—both separately and in combination—for identification of tumor tissue was computed for variable discrimination thresholds to evaluate its receiver operator characteristic (ROC). An association between ADC, MET and Gleason score was tested by the non-parametric Spearman ρ-test. Results. The average ADC-value was 1.65 ± 0.32mm²/s × 10⁻³ in normal tissue and 0.96±0.24 mm²/s × 10⁻³ in tumor tissue (mean ± 1 SD). MET was 0.418 ± 0.431 in normal tissue and 2.010 ± 1.649 in tumor tissue. The area under the ROC curve was 0.966 (95%-confidence interval 0.941–0.991) and 0.943 (0.918–0.968) for DWI and MRS, respectively. There was a highly significant negative correlation between ADC-value and the Gleason score in the tumor-positive tissue probes (n = 62, ρ = −0.405, P = .001). MRS did not show a significant correlation with the Gleason score (ρ = 0.117, P = .366). By using both the DWI and MRS, the regression model provided sensitivity and specificity for detection of tumor of 91.9% and 98.3%, respectively. Conclusion. The results of our study showed that both DWI and MRS should be considered as an additional and complementary tool to the T2-weighted MRI for detecting prostate cancer.

Correlation of endorectal 2D JPRESS findings with pathological Gleason scores in prostate cancer patients

To determine the metabolite ratios of (Cho + Cr)/Cit and (Cho + Cr)/Spm in patients with two ranges of pathological Gleason scores, namely (3 + 4) and (4 + 3). By using the localized two-dimensional (2D) J-resolved spectroscopy (JPRESS) technique, the metabolites ratios can be calculated and correlated with prostate cancer aggressiveness. A total of 24 patients who underwent endorectal 2D JPRESS between April 2006 and July 2007 were included in this study. The 2D JPRESS voxel was localized predominantly in the peripheral zone suspected for malignancy based on pathology. Using the metabolites such as total choline (Cho), creatine (Cr), spermine (Spm) and citrate (Cit), the ratios (Cho + Cr)/Cit and (Cho + Cr)/Spm were calculated. In 14 prostate cancer patients who had a final pathologic Gleason scores of i) (3 + 4 = 7, n = 7) and ii) (4 + 3 = 7, n = 7), the metabolite ratios (mean +/- SD) of (Cho + Cr)/Cit and (Cho + Cr)/Spm were calculated using the 2D JPRESS spectra as follows: i) (1.48 +/- 0.83) and (1.59 +/- 0.73); ii) (2.90 +/- 0.94) and (2.71 +/- 1.47), respectively. Higher percentage of aggressive disease correlates with higher metabolites ratio. Our pilot study suggests that 2D JPRESS can be reliably evaluated in a clinical setting using an endorectal coil. In addition to the citrate ratio, the spermine ratio also correlates with pathology based Gleason score.

Relative biological effectiveness and cell-killing efficacy of continuous low-dose-rate 125I seeds on prostate carcinoma cells in vitro

The aim of this study was to determine the effects of (125)I seeds on prostate carcinoma (PC3) cells. The relative biological effectiveness of (125)I seeds on PC3 cells with respect to (60)Co gamma rays was 1.4. Both 4 Gy of (60)Co gamma ray and (125)I seed irradiation increased the percentage of cells in G(2) phase, but there was no significant difference between these 2 types of radiation. Significantly, (125)I seeds induced higher apoptotic rates of PC3 cells compared with (60)Co gamma ray irradiation. Furthermore, Bcl-2 expression, but not caspase-3 activity, in PC3 cells was downregulated after irradiation with (125)I seed or (60)Co gamma rays.

The adjunctive use of power Doppler imaging in the preoperative assessment of prostate cancer

OBJECTIVE

To determine if the adjunctive use of power Doppler imaging (PDI) could provide prognostic utility in the treatment of prostate cancer, as an accurate prediction of the clinical behaviour of prostate cancer is important to determine appropriate treatment.

PATIENTS AND METHODS

Most centres rely on a digital rectal examination or transrectal ultrasonography (TRUS) to assess the clinical stage of patients. In 2002, we began using a standardized form to evaluate TRUS findings and PDI findings. We compared preoperative clinical findings with those from pathological analysis of 620 radical prostatectomy specimens from 2002 to 2007.

RESULTS

The mean (sd) patient age was 58 (6.6) years with a mean prostate-specific antigen (PSA) level of 7.0 (4.5) ng/mL. Of the 620 specimens 157 (25.3%) had evidence of extracapsular extension on pathological evaluation; 443 (71.5%) men had a hypervascular lesion seen on TRUS, while 177 (28.5%) patients had none. There was no difference in preoperative PSA level, grade or stage of tumour. Furthermore, rates of biochemical recurrence or secondary treatment did not differ based on PDI findings. As a tool to help locate prostate tumours, PDI improved the specificity of TRUS but did not improve the overall accuracy or sensitivity.

CONCLUSION

PDI provides little prognostic utility to assess risk in prostate cancer. However, PDI might improve the specificity of TRUS in identifying prostate tumours and could have a role in image guidance for focal therapy of prostate cancer.

PET imaging of VPAC1 expression in experimental and spontaneous prostate cancer

Among U.S. men, prostate cancer (PC) accounts for 29% of all newly diagnosed cancers. A reliable scintigraphic agent to image PC and its metastatic or recurrent lesions and to determine the effectiveness of its treatment will contribute to the management of this disease. All PC overexpresses VPAC1 receptors. This investigation evaluated a probe specific for a (64)Cu-labeled receptor for PET imaging of experimental human PC in athymic nude mice and spontaneously grown PC in transgenic mice.

METHODS

The probe, TP3939, was synthesized, purified, and labeled with (64)Cu and (99m)Tc. Using a muscle relaxivity assay, biologic activity was assessed and inhibitory concentrations of 50% calculated. Receptor affinity (Kd) for human PC3 cells was determined using (99m)Tc-TP3939 and (64)CuCl(2.) Blood clearance and in vivo stability were studied. After intravenous administration of either (64)Cu-TP3939 or (64)CuCl(2) in PC3 xenografts and in transgenic mice, PET/CT images were acquired. Prostate histology served as the gold standard. Organ distribution studies (percentage injected dose per gram [%ID/g]) in normal prostate were performed. The ratios of tumor to muscle, tumor to blood, normal prostate to muscle, and tumor to normal prostate were determined.

RESULTS

Chemical and radiochemical purities of TP3939 were 96.8% and 98% +/- 2%, respectively. Inhibitory concentrations of 50% and affinity constants were 4.4 x 10(-8) M and 0.77 x 10(-9) M, respectively, for TP3939 and 9.1 x 10(-8) M and 15 x 10(-9) M, respectively, for vasoactive intestinal peptide 28. Binding of (64)CuCl(2) to PC3 was nonspecific. Blood clearance was rapid. In vivo transchelation of (64)Cu-TP3939 to plasma proteins was less than 15%. (64)Cu-TP3939 uptake in PC was 7.48 +/- 3.63 %ID/g at 4 h and 5.78 +/- 0.66 %ID/g at 24 h after injection and was significantly (P < 0.05) greater than with (64)CuCl(2) (4.79 +/- 0.34 %ID/g and 4.03 +/- 0.83 %ID/g at 4 and 24 h, respectively). The ratios of PC to normal prostate at 4 and 24 h were 4 and 2.7, respectively. (64)Cu-TP3939 distinctly imaged histologic grade IV prostate intraepithelial neoplasia in transgenic mice, but (18)F-FDG and CT did not.

CONCLUSION

Data indicate that TP3939, with its uncompromised biologic activity, delineated xenografts and cases of occult PC that were not detectable with (18)F-FDG. (64)Cu-TP3939 is a promising probe for PET imaging of PC. It may also be useful for localizing recurrent lesions and for determining the effectiveness of its treatment.

Advances in transrectal ultrasound imaging of the prostate

Grayscale imaging of the prostate is the basic method for diagnostic evaluation and biopsy guidance. Doppler imaging may improve sensitivity for detection of prostate cancer. Microbubble contrast agents represent a major advance to more selectively demonstrate neovascular flow within the prostate. Recently, real-time elastography has been introduced to improve detection of cancer based upon changes in tissue stiffness. As diagnostic methods improve, the ultimate hope is to eliminate biopsy in patients without cancer. New ultrasound-based treatment systems, such as high-intensity focused ultrasound ablative therapy for prostate cancer, may someday allow diagnosis and treatment of prostate cancer to be completed in one sitting.

Power Doppler ultrasonography of the feeding arteries of the prostate gland: a novel approach to the diagnosis of prostate cancer?

OBJECTIVE

The purpose of this study was to assess the role of spectral Doppler ultrasonographic parameters of the feeding arteries of the prostate for the detection of prostate cancer.

METHODS

A total of 55 patients referred for prostate biopsy with a mean age of 66.4 years (range, 46-82 years) were included. In each patient, Doppler indices from bilateral capsular and urethral arteries were obtained. The indices were compared with regard to malignant (group A) and benign (group B) subgroups of histopathologic outcomes of transrectal ultrasonographically guided prostate biopsy for each side (n = 19 and n = 91 for groups A and B, respectively) and to assess whether the indices were significantly altered on the side with cancer compared with the contralateral side.

RESULTS

The mean pulsatility index value for the capsular artery of group A (1.49 +/- 0.57) was significantly lower than that of group B (1.71 +/- 0.52; P = .048). The mean resistive index and systolic/diastolic ratio for the capsular artery of group A (0.78 +/- 0.10 and 5.40 +/- 2.74, respectively) were lower than those of group B (0.82 +/- 0.08 and 7.40 +/- 4.91) despite being statistically insignificant (P = .075 and .119, respectively).

CONCLUSIONS

Spectral waveform measurements by power Doppler transrectal ultrasonography may be useful in differentiating prostate cancer from benign hypertrophy. Further research is needed to elucidate the potential of spectral Doppler indices of the capsular and urethral arteries.

Optimal cost-effective staging evaluations in prostate cancer

A new diagnosis of prostate cancer presents to both the patient and physician questions regarding the best approach for further assessing the extent of disease prior to selecting a treatment strategy. In addition to the initial clinical data such as serum prostate-specific antigen level, findings on digital rectal examination, and core biopsy Gleason score, several procedures and imaging modalities are available to further stage newly diagnosed prostate cancer. A substantial percentage of the cost of managing prostate cancer is directly related to staging evaluations. Often, staging evaluations are performed that have limited test performance characteristics, subject the patient to unnecessary morbidity, or simply do not provide additional useful clinical information. It is important that the physician be familiar with the indications for the available staging modalities as well as the test performance characteristics in order to proceed appropriately and in an economically judicious fashion. This paper reviews the literature on this topic and summarizes previous experiences with procedures and imaging modalities for staging newly diagnosed prostate cancer.

Imaging in genitourinary cancer from the urologists' perspective

It is well established that advances in imaging may lead to early cancer detection, more accurate tumour staging and consequently adequate treatment, better monitoring of the disease and enhanced surveillance for recurrences after treatment. This manuscript reviews the current use of imaging in genitourinary cancer and explores the impact of imaging findings in clinical management. Additionally, an effort has been made to present the emerging imaging modalities and also their possible role in diagnosis and treatment of these cancers.

Prostate cancer detection: magnetic resonance (MR) spectroscopic imaging

Magnetic resonance spectroscopic imaging (MRSI) represents a noninvasive technique to extend the diagnostic evaluation of prostatic cancer, beyond the morphologic information provided by MR imaging throughout the detection of cellular metabolites (choline and citrate). MRSI combined with the anatomical information provided by MRI can improve the assessment cancer location and extent within the prostate, extracapsular spread and cancer aggressiveness; both before and after treatment. We review the performance of MRI with MRSI and the role in the detection, localization, staging and management of the patient pre- and posttherapy for prostate cancer.

Sensitivity and specificity evaluation of endorectal magnetic resonance imaging and transrectal sonography in the staging of prostate cancer

Objectives

Nowadays endorectal probes for Magnetic Resonance Imaging (MRI) have better resolutions, which allows to acquire high-level images of prostate and to improve the MRI sensitivity and specificity to determine the cancer volume and the extraprostatic extension. The objective of the present study is to evaluate the sensitivity and diagnostic accuracy of endorectal MRI for identifying the local extension of prostate carcinoma compared to transrectal sonography (TRUS) of prostate.

Materials and Methods

The study included 81 patients with clinical suspect of cancer and/or elevated values of serum prostate specific antigen (PSA), who underwent endorectal MRI with 1.5 T endorectal probe before transrectal biopsy. Patients with localized prostate cancer underwent radical surgery. The results of endorectal MRI were compared to those of TRUS and histopathological examination outcomes.

Results

15 of the 81 enrolled patients had extraprostatic localization of cancer, which was assessed through TRUS in 4 cases only (26%), and through MRI in 7 cases (46%). A seminal vesicle involvement was present in 10 patients, detected by MRI in 5 cases and in no cases by TRUS.

Discussion and Conclusions

Data are similar to the findings collected by several Authors. The endorectal MRI has a better accuracy in staging prostate cancer compared to TRUS. Nevertheless, this procedure has some limits: little availability of equipment in hospitals, physicians’ little experience, and higher costs compared to TRUS.

Transrectal ultrasound guided biopsy for detecting prostate cancer: can random biopsies be reduced using the 4-dimensional technique?

We present our experience with a new technique of real time 3-dimensional sonography -- "4-dimensional Transrectal ultrasound (TRUS)" guided prostate biopsy. A total of 64 patients suspected of having prostate cancer based on an elevated prostate-specific antigen (greater than 4 ng/ml) formed the study group. A voluson (General Electric Vivid 3) ultrasound machine equipped with a transrectal 5-8 MHz curvilinear transducer was used. Sonography-guided prostate biopsy was performed following prostate imaging and volume calculation using 3D and 4D imaging. Biopsies of tumor suspicious areas, if present, as well as random biopsies were done. Histopathology showed prostate cancer in 15 (23.4%) and benign prostatic conditions in 49 (76.6%). TRUS examination in the 15 detected prostatic cancers showed that 6(40%) were hypoechoic, 4 (26.7%) were of mixed hypo and hyper echogenicity, 1 (6.7%) was hyperechoic, and 4 (26.7%) were isoechoic. TRUS finding of a hypoechoic lesion was significantly associated with malignancy. Other TRUS findings such as texture, calcification, and cysts did not show any association with malignancy. Mortality was zero after ultrasound-guided prostate biopsy. TRUS is the diagnostic test of choice in detection of prostate cancer. With advances in the technique of TRUS, effort is being made to identify more subtle lesions in order to reduce random biopsies. 4-Dimensional TRUS does improve the diagnostic accuracy but there is still a group of patients with "invisible" cancers. Therefore, the policy of random biopsies has to be continued till this incidence can be eliminated.

Prostate Cancer Imaging—What the Urologic Oncologist Needs to Know

Appropriate imaging for prostate cancer patients depends on the clinical disease state of the patient and the question being asked. For patients who do not have a cancer diagnosis, ultrasound is the standard approach, in combination with a sextant biopsy. In the future, contrast-enhanced ultrasound and MR imaging-directed biopsy may improve biopsy yield and decrease biopsy number. For clinically localized disease, endorectal coil MR imaging and bone scanning may play a role in patients who have risk factors for extracapsular extension, but more data are needed to define the role of MR spectroscopy and lymphtrophic nanoparticle MR imaging. In the rising prostate-specific antigen (PSA) setting after definitive local therapy, endorectal coil MR imaging may help define local recurrence, whereas bone scanning can be useful in the setting of higher PSA or rapid PSA velocity.

New Clinical Imaging Modalities in Prostate Cancer

In all prostate cancer disease states, exciting novel imaging technology is being tested that may affect the future care of our patients. New US, MRI, and nuclear medicine techniques are improving both the ability to stage patients and to follow treatment-related changes. See Table 3 for a summary of these novel imaging techniques. Important issues still need to be resolved, including standardizing patient populations within trials, demonstrating the reproducibility of these techniques between different centers, and understanding how information gained from these techniques should influence patient care. We eagerly await answers to these questions.

The evolution of imaging in advanced prostate cancer

Medical advances will be driven by the enhancement of imaging for diagnosis, refinement of treatment, and evaluation of treatment efficacy. The convergence of technology in materials science, biology, and the computer industry has greatly advanced diagnostic imaging. Precision in control of the spatial and temporal properties of light and its heterogeneous scattering properties have extended our capability for imaging. Refinements in radioimmunoscintigraphy for image acquisition, fusion of images, and outcome data now suggest use for image-guided therapy. Novel MRI agents appear to provide significant imaging capabilities to detect malignant lymph nodes. Future applications of optical coherence tomography, electron paramagnetic resonance imaging, nanotechnology, molecular imaging, and hyperspectral spectroscopy promise further refinements to image tissues for diagnosis.

[MRI and staging evaluation of prostate cancer]

MRI can assess local and locoregional spread of a newly diagnosed prostate cancer by detecting extracapsular extension (ECE), seminal vesicle invasion (SVI) and lymph node invasion. Endorectal MRI remains the only accurate means to assess local extension. Pelvic MRI with surface coils and the use of superparamagnetic particules provide the sensitivity and the specificity which have never been obtained by the sole measurement of node size of the lymphatic chains draining the prostate gland. With the endorectal coil, only direct signs of extracapsular extension have been maintained and indirect signs have been discarded, giving their too low specificity. Early SVI can only be consistently detected if result of TRUS guided biopsies show involvement of the prostate base. With the pelvic phased array coil, superparamagnetic particules show that metastatic lymph nodes have a specific MR signal which can be detected in normal size nodes. Indications of imaging relies on results of parametrers available before MR imaging. More important than PSA level and Gleason score on biopsies is the so called quantitative histology, represented by the number of sextants involved by tumor and the amount of cancer (measured in mm of tumor) present on biopsies which determine a risk of extraprostatic spread. Of the risk of extraprostatic spread depends indication of MR, which is most probably unnecessary in patients at low risk (<20%) of extraprostatic extension.

Real-Time Transrectal Ultrasound Guidance During Laparoscopic Radical Prostatectomy: Impact on Surgical Margins

PURPOSE

We evaluated whether intraoperative real-time TRUS navigation during LRP can decrease the incidence of positive surgical margins.

MATERIALS AND METHODS

Since March 2001, 294 patients with clinically organ confined prostate cancer undergoing LRP have been retrospectively divided into 2 groups, including group 1-217 who underwent LRP without TRUS from March 2001 to February 2003 and group 2-77 who have undergone LRP with TRUS since March 2003. Various baseline parameters were similar between the groups. Before March 2001 the senior surgeon had already performed more than 50 cases of LRP, thus, gaining reasonable familiarity with the technique.

RESULTS

Compared to group 1, group 2 had a significantly decreased rate of positive surgical margins in patients with pT3 disease (57% vs 18%, p = 0.002). Positive margin rates also decreased in our overall experience (29% vs 9%, p = 0.0002). Intraoperative TRUS correctly predicted pT2 and pT3 disease in 85% and 86% of patients, respectively. Of the 54 TRUS visualized hypoechoic lesions at sites corresponding to biopsy proven cancer extracapsular extension was suspected in 31, leading to a real-time recommendation of calibrated wider, site specific dissection to achieve negative surgical margins.

CONCLUSIONS

Intraoperative TRUS monitoring during LRP allows individualized, precise dissection tailored to the specific prostate contour anatomy, thus, compensating for the muted tactile feedback of laparoscopy. In what is to our knowledge the initial experience real-time TRUS guidance significantly decreased the incidence of positive surgical margins during LRP. In the future this concept of rectum based, intraoperative real-time navigation may facilitate a more sophisticated performance of radical prostatectomy.

Nuclear Medicine Studies of the Prostate, Testes, and Bladder

During the last decade, there has been a significant advancement in imaging of urologic diseases. Transrectal ultrasound (TRUS), computerized tomography (CT), magnetic resonance imaging (MRI), magnetic resonance spectroscopy (MRS), and positron emission tomography (PET) are still experiencing new developments in urology. Despite these many technological advances, the initial diagnostic procedure for a patient with suspected prostate cancer (PC) is multiple site blind prostate biopsies. There is a need for a noninvasive metabolic imaging modality to direct the site of biopsy to decrease the sampling error. MRS seems promising but as it is a costly and more time-consuming test, further studies are needed to evaluate its clinical utility. Currently, PET does not play any role to direct biopsy. Acetate and choline appear to be better tracers than FDG for the detection of a prostate lesion, however, further well-organized studies are needed before any of these agents can be used clinically. Incidental detection of intense focal uptake in the prostate during whole body PET scanning should be evaluated with prostate-specific antigen (PSA) and TRUS-guided biopsy. Although FDG is inferior to other tracers for primary staging, it may be useful in selected patients with suspected high-grade cancer. The role of ProstaScint scan is still controversial for detection of recurrent PC. This study may be helpful for evaluating nodal metastases when PSA is elevated and bone scan is negative. Bone scan remains the study of choice when bone metastases are suspected (PSA>15-20 ng/mL+/-bone pain). Acetate and choline provide better accuracy than FDG in the detection of local soft tissue disease, nodal involvement, and distant metastases. High FDG uptake may be indicative of more aggressive and possibly androgen-independent disease. PET/CT with any of the above PET tracers will most likely be preferred to the PET scan alone due to better localization of a hot lesion in PET/CT. Nuclear medicine studies also have been used to evaluate acute scrotum and testicular neoplasms. Scrotal scintigraphy has lost its popularity to Doppler ultrasound in the evaluation of the acute scrotum. In testicular tumors, FDG-PET appears to be superior to conventional imaging modalities in initial staging, detection of residual/recurrence, and monitoring treatment response. Tumor markers after treatment occasionally are elevated and cannot locate the site of recurrence, FDG-PET can play a very important role in this regard. Nuclear medicine studies also have been used to evaluate diseases of the urinary bladder. Radionuclide cystography is more sensitive and has less than 1/20 the radiation exposure of the conventional contrast enhanced micturating cystourethrogram (MCU). However, the utility of FDG-PET in the evaluation of bladder cancer seems to be limited to the evaluation of distant metastases. 11C-Methionine and choline may be a better option for local and nodal disease due to their negligible excretion in the urine.

Accuracy of prostate volume measurements using transrectal multiplanar three-dimensional sonography

The aim of this study is to evaluate the accuracy of three-dimensional (3D) ultrasound in comparison with conventional bidimensional (2D) sonography in prostatic calculations. The study was performed using a Kretztechnik Voluson 530D machine with a 7.5 MHz endocavitary transducer. From March 1998 to March 2000, we examined 80 patients (63-74 years, mean 68 years). There were 59 patients with benign prostate hypertrophy (BPH) and 21 with prostate cancer awaiting a radical prostatectomy. The mean absolute error in 3D ultrasound measurement was +/-0.2-3 mL. (range of error was 6.5%). Volume measurement using 2D ultrasound methods was much less accurate than 3D ultrasound methods: +/-0.4-5 mL. (range of error was 35%). Both 2D and 3D measurements show that the margin of error depends on the frequent presence of a third prostatic lobe, on the morphology, and on the size of the prostatic gland. The precise estimation of prostate volumes may provide information on the real effectiveness of some therapies that act on the reduction in volume of benign alteration, such as in prostatic hypertrophy, and may eliminate the current limits of 2D sonography with a significant clinical contribution for virtually no extra cost.

Differentiation of noncancerous tissue and cancer lesions by apparent diffusion coefficient values in transition and peripheral zones of the prostate

PURPOSE

To compare the apparent diffusion coefficient (ADC) values of prostate cancer in both the peripheral zone (PZ) and the transition zone (TZ) with those of benign tissue in the same zone using echo-planar diffusion weighted imaging with a parallel imaging technique.

MATERIALS AND METHODS

A total of 29 consecutive male patients (mean age 61.3 years, age range 53-88 years) with suspected prostate cancer were referred for MR imaging. All patients underwent transrectal ultrasound (TRUS)-guided biopsy of the prostate after MR imaging at 1.5 T, including ADC. For each patient, seven to 10 specimens were obtained from the prostate, and regions of interest (ROIs) were drawn on the ADC map by referring to the urologist's illustration of TRUS-guided biopsy sites. ADC values of cancerous tissue in both the PZ and TZ were compared to those of noncancerous tissue in the same zone.

RESULTS

Out of 29 patients, 23 had cancer tissue. In the 23 patients with cancer, the mean ADC value of all cancer ROIs and that of all noncancer ROIs, respectively, were 1.11 +/- 0.41 x 10(-3) and 1.68 +/- 0.40 x 10(-3) mm(2)/second (values are mean +/- SD) (P < 0.01). The mean ADC value of TZ cancer ROIs and that of TZ noncancer ROIs, respectively, were 1.13 +/- 0.42 x 10(-3) and 1.58 +/- 0.37 x 10(-3) mm(2)/second (P < 0.01).

CONCLUSIONS

ADC measurement with a parallel imaging technique showed that ADC values of prostate cancer in both the PZ and TZ were significantly lower than those of benign tissue in the PZ and TZ, respectively.

In vivo uptake of [11C]choline does not correlate with cell proliferation in human prostate cancer

PURPOSE

Prostate cancer is the second leading cause of death from cancer among US men. Positron emission tomography (PET) with [(11)C]choline has been shown to be useful in the staging and detection of prostate cancer. The background of the increased uptake of choline in human prostate cancer is not completely understood. The aim of this study was to prospectively investigate the relationship between the [(11)C]choline uptake and the cell proliferation in human prostate cancer.

METHODS

Prostate cancer tissue from 18 patients who had undergone a radical prostatectomy for histologically proven disease was studied. An [(11)C]choline PET scan was performed prior to surgery. Post-prostatectomy specimens were prepared and stained with the antibody MIB-1 for Ki-67, which depicts proliferation. Two independent observers counted the amount of stained nuclei per specimen.

RESULTS

Prostate cancer showed Ki-67 staining and high uptake of [(11)C]choline. Statistical analysis showed no significant correlation between [(11)C]choline uptake and Ki-67 staining (R=0.23; P=0.34). No significant relationships were found between the uptake of [(11)C]choline (SUV) and either preoperative PSA (R=0.14; P=0.55) or Gleason sum score (R=0.28; P=0.25).

CONCLUSION

In vivo uptake of [(11)C]choline does not correlate with cell proliferation in human prostate cancer as depicted by Ki-67. Our results suggest that a process other than proliferation is responsible for the uptake of [(11)C]choline in prostate cancer.

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is a useful modality for the precise detection and staging of early prostate cancer

BACKGROUND

The aim of this study was to visualize early stage prostate cancer (Cap) in a clinical setting. In previous studies, the results of magnetic resonance imaging (MRI) for screening Cap have rarely been confirmed by well-designed multisite prostate biopsy.

METHODS

The prostate glands of 90 men with elevated prostate-specific antigen (PSA) were imaged by dynamic contrast-enhanced MRI (DCE-MRI) before transrectal ultrasound-guided 14-cores prostate biopsy. Each core was divided into three subcore fractions (total of 42 fractions) to generate a histological localization diagram, which was compared with localization-visualized DCE-MRI.

RESULTS

The detection rate of Cap in 57 patients with PSA < 10.0 ng/ml was 36.8% as determined by the initial biopsy. DCE-MRI uncovered 92.9% of the clinically significant Caps and its specificity was 96.2% for the first biopsy session. One case with positive DCE-MRI and a negative primary biopsy was positive with additional biopsies. All of 26 DCE-MRI positive cases had significant Cap, and two of eight patients with histological Cap and negative or equivocal imaging had significant cancer. In total, 9 of 20 cases with DCE-MRI stage T2 underwent radical prostatectomy. All of them had organ-confined disease, although 33-77% (mean 63%) of them were expected to be rated T3 or higher by Partin's table.

CONCLUSIONS

DCE-MRI can identify early stage Cap with high sensitivity and specificity, and can predict the histological grade to some extent. DCE-MRI prior to biopsy should be applied to younger patients with surgical indications. Otherwise, we recommend the definitive diagnosis of Cap by utilizing DCE-MRI alone.

Three-dimensional 1H-magnetic resonance spectroscopy of the prostate in clinical practice: technique and results in patients with elevated prostate-specific antigen and negative or no previous prostate biopsies

To assess the benefit of routinely used three-dimensional 1H-spectroscopy of the prostate combined with magnetic resonance imaging in patients with elevated prostate-specific antigen (PSA) levels and negative or no previous prostate biopsies. Fifty-four patients were examined with our combined imaging protocol, which consisted of transversal, coronal and sagittal T2-weighted fast spin echo sequences. For spectroscopy, we used a three-dimensional chemical shift imaging spin echo (3D-CSI-SE) sequence. The study population consisted of patients with elevated PSA levels and histologically proven prostate carcinoma and patients with elevated PSA levels and negative or no previous prostate biopsies. Examination time was 31 min, a time feasible for routine use. Eighty-eight tumour voxels and 67 control voxels of 27 patients with histologically proven prostate carcinoma were analysed. Ratios of (choline + creatine)/citrate [(Cho + Crea)/Cit] below 0.6 were classified as normal and above 0.6 as pathological. Applying this classification to 20 patients with tumour-suspicious lesions of the prostate and negative or no previous prostate biopsies, we could obtain a sensitivity and specificity for tumour detection of 100% and 69%, respectively. Our combined imaging protocol is feasible for routine use and can add valuable information for the diagnostic management of patients with negative or no previous prostate biopsies.

[Prostate cancer: Diagnosis and staging]

The discovery and the use of serum prostate specific antigen (PSA) has considerably improved the diagnosis of prostate cancer during the past 20 years. Before PSA era, early diagnosis was only based on the digital rectal examination (DRE) of which the Limitations have been evidenced; over half of the tumours diagnosed by such means had already spread out of the prostate and were incurable. Assessment of serum PSA has allowed the diagnosis to be made at an earlier stage of the disease, curable by current treatments. Whichever the diagnostic tools, transrectal ultrasound (TRUS) prostatic biopsies remain necessary for diagnosis ascertainment, taking into account the low specificity of PSA assessment. The feasibility of a diagnosis at an early and curable stage of the disease has logically resulted in screening procedures aimed at reducing the high mortality related to prostate cancer. The numerous publications on prostate cancer screening provide precise information on the accuracy of available diagnostic means (PSA, DRE, TRUS, combined PSA and DRE), on the characteristics of screened tumours (stage and differentiation), and also on the population of men likely to benefit from the screening (age at beginning and end of the screening, frequency of PSA testing, identification of the men with ethnic and/or genetic predisposition). In those early diagnosed prostate cancers, the assessment of loco-regional cancer extension (extracapsular and/or, microscopic nodal involvement), remains unsatisfactory because no imaging technique (ultrasonography, CT scan, MRI,...) allows visualising the tumour itself or microscopic metastases. Nevertheless, the combination of multiple parameters such as DRE data, PSA level, biopsy data and tumour differentiation helps approaching with an increasing precision (nomograms) the true pathologic stage of the disease. Such advances allow distinguishing, among the very heterogeneous group of prostate cancers, tumours that differ from one to another in terms of disease stage, progression and prognosis, which is helpful for the determination of an adapted therapeutic strategy.

Détection du cancer de la prostate par IRM endorectale dynamique et spectroscopique-proton

PURPOSE

Determine the feasibility of dynamic gadolinium enhanced MRI and spectroscopic imaging in routine clinical practice using standard equipment and its usefulness for patients with negative biopsies and high degree of suspicion of prostate cancer.

PATIENTS AND METHODS

Fifty five patients underwent endorectal MRI using T2W spin echo (SE) imaging, dynamic gadolinium enhanced imaging and proton spectroscopic imaging before repeat US-guided transrectal biopsies. The statistical analysis consisted in the correlation of the results obtained with each of the two MRI techniques and the results of the biopsies in the corresponding prostate lobe.

RESULTS

32 patients were included in the analysis. Biopsies revealed cancer for 15 patients. The statistical analysis showed a lack of significant correlation between T2W-SE imaging and biopsy results. A correlation with statistical significance was found between dynamic gadolinium enhanced imaging and biopsies (p=0,0018) and between spectroscopic imaging results and biopsies in the corresponding lobe (p=0,0001).

CONCLUSION

Endorectal MRI with a standard clinical equipment using dynamic gadolinium enhanced imaging and spectroscopic imaging may be used in clinical routine to improve detection and localization in prostate cancer compared to T2 weighted spin echo imaging.

Update of staging and risk assessment for prostate cancer patients

PURPOSE OF REVIEW

This paper will review the current staging system for prostate adenocarcinoma patients, and will also review new information that can be combined with clinical and pathological staging in order to assess a patient's risk of success or failure of treatment.

RECENT FINDINGS

There has been significant stage migration of prostate cancer patients in the past 15 years, such that patients are currently being diagnosed younger, with lower clinical stages and serum prostate-specific antigen levels, and a lower risk of metastatic disease than previously. The incorporation of the results of extended prostate biopsy schemes, with stage, grade and serum prostate-specific antigen levels, improves the risk assessment of newly diagnosed prostate cancer patients. New imaging techniques, such as transrectal ultrasound Doppler flow and magnetic resonance spectroscopy hold promise for improving risk assessment. Molecular biomarkers may improve risk assessment in the future, although none are currently approved by the US Food and Drug Administration for this indication. Gene chip arrays may further refine risk assessment and assist with the identification of therapeutic targets.

SUMMARY

There has been significant stage migration of prostate cancer patients in the prostate-specific antigen era. Incorporating biopsy information into nomograms and risk assessment equations improves upon clinical staging and risk assessment. New imaging techniques, molecular markers and gene chip arrays hold promise for future risk assessment.