Pretreatment endorectal magnetic resonance imaging and magnetic resonance spectroscopic imaging features of prostate cancer as predictors of response to external beam radiotherapy

Prospective study of HDR brachytherapy (BT), external beam radiotherapy (EBRT) and androgen deprivation therapy (ADT): 10-years experience of an MRI-guided approach

OBJECTIVES

To evaluate the predictive factors for biochemical failure and distant metastases in a prospective cohort of patients with localized prostate cancer treated with the combination of HDR BT and EBRT.

METHODS AND MATERIALS

Patients with intermediate (IR) or high-risk (HR) prostate adenocarcinoma received a single fraction of HDR of 15 Gy combined with RT of 37.5 Gy in 15 fractions. ADT duration was used depending on risk-group. Descriptive analyses were performed. Univariate and multivariate Hazard Ratios were obtained. Finally, the Kaplan-Meier model was used to describe the survival of the events of interest.

RESULTS

309 patients were treated prospectively (199 were IR and 110 HR). Median age was 72 years; 58.3 % were MRI stage ≤ T2c, 34.1 % T3a and 7.6 % T3b; ISUP-grade 1-3 in 78.9 % and ISUP 4-5 in 21.1 %. 71.8 % of patients had ≤ 50 % positive-cores in biopsy and 28.2 % had > 50 %. Median pre-treatment PSA was 9.9 ng/mL. After a median follow-up of 88 months, 41 patients presented biochemical failure and 18 developed distant metastases. Multivariate cox-regression analyses found that MR-T3b Stage (HR 3.88, p = 0.001) and ADT use (HR 3.99, p = 0.03) were the only predictive factors for biochemical failure and the number of positive cores (>50 %) the only independent predictive factor of distant metastases (HR 4.36, p = 0.002).

CONCLUSIONS

Patients with mpMRI evidence of invasion of the SV and involvement of more than 50% of the cores in the prostate biopsy are patients with a higher risk of presenting a biochemical recurrence or developing metastasis due to their prostate cancer, respectively.

Predicting Biochemical Failure in Irradiated Patients With Prostate Cancer by Tumour Volume Measured by Multiparametric MRI

BACKGROUND/AIM

We examined the prognostic value of intraprostatic gross tumour volume (GTV) as measured by multiparametric MRI (mpMRI) in patients with prostate cancer following (primary) external beam radiation therapy (EBRT).

PATIENTS AND METHODS

In a retrospective monocentric study, we analysed patients with prostate cancer (PCa) after EBRT. GTV was delineated in pre-treatment mpMRI (GTV-MRI) using T2-weighted images. Cox-regression analyses were performed considering biochemical failure recurrence-free survival (BRFS) as outcome variable.

RESULTS

Among 131 patients, after a median follow-up of 57 months, biochemical failure occurred in 27 (21%). GTV-MRI was not correlated with % of positive biopsy cores, Gleason score and initial PSA (all r<0.2) and only moderately correlated with cT stage (r=0.32). In univariate analysis, cT stage, Gleason score and GTV-MRI were higher in subjects with shorter BRFS (p<0.05). GTV-MRI remained a significant predictor for BRFS in multivariate analyses, independent of Gleason score and cT stage.

CONCLUSION

GTV, defined using mpMRI, provides incremental prognostic value for BRFS, independent of established risk factors. This supports the implementation of imaging-based GTV for risk-stratification, although further validation is needed.

PI-RADS score is associated with biochemical control and distant metastasis in men with intermediate-risk and high-risk prostate cancer treated with radiation therapy

BACKGROUND

Novel methods of risk stratification are needed for men with prostate cancer. The Prostate Imaging Reporting and Data System (PI-RADS) uses multiparametric MRI (mpMRI) to assign a score indicating the likelihood of clinically significant prostate cancer. We evaluated pretreatment mpMRI findings, including PI-RADS score, as a marker for outcome in patients treated with primary radiation therapy (RT).

METHODS

One hundred and twenty-three men, 64% and 36% of whom had National Comprehensive Cancer Network (NCCN) intermediate-risk and high-risk disease, respectively, underwent mpMRI prior to RT. PI-RADS score and size of the largest nodule were analyzed with respect to freedom from biochemical failure (FFBF) and freedom from distant metastasis.

RESULTS

A PI-RADS score of ≤3, 4, or 5 was defined in 7%, 49%, and 44%; with a median nodule size of 0, 8, and 18 mm, respectively (P < 0.001). Median follow-up was 67 months. Men with PI-RADS ≤ 3, 4, or 5 disease had 7-year FFBF of 100%, 92%, and 65% (P = 0.002), and a 7-year freedom from distant metastasis of 100%, 100%, and 82%, respectively (P = 0.014). PI-RADS (Hazard Ratio 5.4 for PI-RADS 5 vs. 4, P = 0.006) remained associated with FFBF when controlling for NCCN risk category (P = 0.063) and receipt of androgen deprivation therapy (P = 0.535). Nodule size was also associated with FFBF (Hazard Ratio 1.08 per mm, P < 0.001) after controlling for NCCN risk category (P = 0.156) and receipt of androgen deprivation therapy (P = 0.776).

CONCLUSION

mpMRI findings, including PI-RADS score and nodule size, may improve risk stratification in men treated with primary RT.

Prognostic Value of Pretreatment MRI in Patients With Prostate Cancer Treated With Radiation Therapy: A Systematic Review and Meta-Analysis

OBJECTIVE. Despite a substantial increase in the use of MRI for pretreatment evaluation of prostate cancer, its prognostic value in patients undergoing radiation therapy (RT) is not well known. Therefore, the purpose of this study was to systematically review the literature and perform a meta-analysis on the prognostic value of pretreatment MRI in patients with prostate cancer who underwent external beam radiation therapy (EBRT) or brachytherapy. MATERIALS AND METHODS. PubMed and Embase databases were searched for studies published on or before March 13, 2019. We included studies that evaluated pretreatment MRI as a prognostic factor in prostate cancer regarding biochemical recurrence (BCR), metastatic failure, and overall or cancer-specific mortality. Effect sizes were measured in terms of the hazard ratio (HR) and were meta-analytically pooled using the random-effects model. The quality of the studies was independently evaluated using the Quality in Prognostic Studies tool. RESULTS. Twelve studies (2205 patients) were included. All studies assessed BCR; metastasis was evaluated in three studies, and mortality was evaluated in one study. Extraprostatic extension (EPE), seminal vesicle invasion (SVI), large tumor size or volume, number of sextants involved, and tumor involvement of prostatic apex were significant prognostic factors of BCR (pooled HRs = 1.50-4.47). EPE, larger tumor size, greater tumor volume, presence of metastatic pelvic lymph nodes (LNs), and presence of SVI were significant risk factors for metastasis (pooled HRs = 1.12-11.96). Pelvic LN metastasis was significantly predictive of cancer-specific mortality (HR = 4.45 [95% CI, 1.30-15.23]). CONCLUSION. Several pretreatment MRI findings were significant prognostic factors in patients with prostate cancer who underwent RT.

Case series illustrating the synergistic use of hydrogel spacer and MR-guidance to increase the radiotherapeutic index for localized prostate cancer

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Polyethylene glycol hydrogel spacer allows radiotherapy in challenging scenarios.

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Polyethylene glycol hydrogel material properties may limit broader applicability.

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MRI-guided brachytherapy unique scenario to use PEG without compromising prostate resolution.

Background

The risk of gastrointestinal (GI) toxicity may limit the use of curative-intent radical radiotherapy (RT) for prostate cancer (PCa) in circumstances where morbidity of treatment may exceed an acceptable threshold. Rectal spacers are used to expand the distance between the anterior rectal wall and the prostate, consequently sparing the rectum from the high-dose region.

Case presentations

We report three clinical scenarios of PCa patients treated at our institution, where risk of RT-associated rectal toxicity may be increased: inflammatory bowel disease (IBD), salvage brachytherapy (BT) after previous external beam RT (EBRT), and tailored dose-escalation with focal BT to the gross tumor volume followed by stereotactic body RT. Prior to RT, a polyethylene glycol (PEG) hydrogel spacer was successfully placed in all cases. Treatment comprised magnetic resonance (MR) guided high dose-rate BT ± EBRT. All patients completed treatment uneventfully, without any significant GI toxicity at last follow-up.

Conclusions

These cases illustrate the utility of PEG hydrogel spacer, where concerns of radiation induced toxicity may have previously limited the application of radiotherapy. The synergistic use of these novel devices together with MR-guided BT may expand the indications and therapeutic index of curative-intent RT-based treatments, while minimizing the risks of GI toxicity.

Multimodal imaging for radiation therapy planning in patients with primary prostate cancer

Implementation of advanced imaging techniques like multiparametric magnetic resonance imaging (mpMRI) or Positron Emission Tomography (PET) in radiation therapy (RT) planning of patients with primary prostate cancer demands several preconditions: accurate staging of the extraprostatic and intraprostatic tumor mass, robust delineation of the intraprostatic gross tumor volume (GTV) and a reproducible characterization of the prostate cancer's biological properties. In the current review we searched for the currently available imaging techniques and we discussed their ability to fulfill these preconditions. We found that current pretreatment imaging was mainly performed with mpMRI and/or Prostate-specific membrane antigen PET imaging. Both techniques offered an accurate detection of the extraprostatic and intraprostatic tumor burden and had a major impact on RT concepts. However, some studies postulated that mpMRI and PSMA PET had complementary information for intraprostatic GTV detection. Moreover, interobserver differences for intraprostatic tumor delineation based on mpMRI were observed. It is currently unclear whether PET based GTV delineation underlies also interobserver heterogeneity. Further research is warranted to answer whether multimodal imaging is able to visualize biological processes related to prostate cancer pathophysiology and radiation resistance.

Pretreatment multiparametric MRI is independently associated with biochemical outcome in men treated with radiation therapy for prostate cancer

PURPOSE

The purpose of this study was to investigate the utility of pre-treatment multiparametric magnetic resonance imaging (mpMRI) in a modern cohort of intermediate and high-risk prostate cancer patients treated with primary radiotherapy.

METHODS AND MATERIALS

One hundred twenty three men with National Comprehensive Cancer Network (NCCN) intermediate or high-risk prostate cancer were treated with primary EBRT and/or brachytherapy and had evaluable pre-treatment mpMRI with endorectal coil. Images were assessed for the presence of radiographic extraprostatic extension (rEPE), seminal vesicle invasion (rSVI), lymph node involvement (LNI), sextant involvement, and largest axial tumor diameter. Imaging characteristics were analyzed along with clinical risk factors against freedom from biochemical failure (FFBF). Median follow-up time was 50 months.

RESULTS

Fourteen (11%) men developed biochemical failure. The 5-year FFBF was 94% in intermediate-risk patients and 82% in high-risk patients (p < 0.01). mpMRI findings including rEPE (29% vs. 66%, p < 0.01), rSVI (6% vs. 25%, p < 0.01), LNI (1% vs. 30%, p < 0.01), and largest axial tumor size> 15 mm (27% vs. 48%, p = 0.02) were identified in men with intermediate vs. high risk prostate cancer, respectively. mpMRI features associated with 5-y FFBF biochemical failure on univariate analysis included rEPE (80% vs 98%), rSVI (55% vs. 96%), LNI (65% vs. 93%), and largest axial tumor size >15mm (81% vs. 94%, all p < 0.01). Men without any high risk MRI finding had a 5-y FFBF of 100% vs. 81% (p < 0.01). Adverse imaging features (HR 8.9, p < 0.01) were independently associated with biochemical failure in a bivariate model analyzed alongside clinical risk category (HR 3.2, p = 0.04).

CONCLUSIONS

Pre-treatment mpMRI findings are strongly associated with biochemical outcomes in a modern cohort of intermediate and high-risk patients treated with primary radiotherapy. mpMRI may aid risk stratification beyond clinical risk factors in men treated with radiation therapy; further study is warranted to better understand how mpMRI can be used to individualize therapy.

Role of Prostate MR Imaging in Radiation Oncology

The use of prostate MR imaging in radiotherapy continues to evolve. This article describes its current application in the selection of treatment regimens, integration in treatment planning or simulation, and assessment of response. An expert consensus statement from the annual MR in RT symposium is presented, as a list of 21 key quality indicators for the practice of MR imaging simulation in prostate cancer. Although imaging requirements generally follow PIRADSv2 guidelines, additional requirements specific to radiotherapy planning are described. MR imaging-only workflows and MR imaging-guided treatment systems are expected to replace conventional computed tomography-based practice, further adding specific requirements for MR imaging in radiotherapy.

Dosimetric feasibility of ablative dose escalated focal monotherapy with MRI-guided high-dose-rate (HDR) brachytherapy for prostate cancer

PURPOSE

To determine the dosimetric feasibility of dose-escalated MRI-guided high-dose-rate brachytherapy (HDR-BT) focal monotherapy for prostate cancer (PCa).

METHODS

In all patients, GTV was defined with mpMRI, and deformably registered onto post-catheter insertion planning MRI. PTV included the GTV plus 9mm craniocaudal and 5mm in every other direction. In discovery-cohort, plans were obtained for each PTV independently aiming to deliver ⩾16.5Gy/fraction (two fraction schedule) while respecting predefined organs-at-risk (OAR) constraints or halted when achieved equivalent single-dose plan (24Gy). Dosimetric results of original and focal HDR-BT plans were evaluated to develop a planning protocol for the validation-cohort.

RESULTS

In discovery-cohort (20-patients, 32-GTVs): PTV D95% ⩾16.5Gy could not be reached in a single plan (3%) and was accomplished (range 16.5-23.8Gy) in 15 GTVs (47%). Single-dose schedule was feasible in 16 (50%) plans. In the validation-cohort (10-patients, 10-GTVs, two separate implants each): plans met acceptable and ideal criteria in 100% and 43-100% respectively. Migration to single-dose treatment schedule was feasible in 7 implants (35%), without relaxing OAR's constraints or increasing the dose (D100% and D35%) to mpMRI-normal prostate (p>0.05).

CONCLUSION

Focal ablative dose-escalated radiation is feasible with the proposed protocol. Prospective studies are warranted to determine the clinical outcomes.

Disparities in staging prostate magnetic resonance imaging utilization for nonmetastatic prostate cancer patients undergoing definitive radiation therapy

PURPOSE

There is growing evidence supporting incorporating multiparametric (mp) magnetic resonance imaging (MRI) scans into risk stratification, active surveillance, and treatment paradigms for prostate cancer. The purpose of our study was to determine whether demographic disparities exist in staging MRI utilization for prostate cancer patients.

METHODS AND MATERIALS

An institutional database of 705 nonmetastatic prostate cancer patients treated with radiation therapy from 2005 through 2013 was used to identify patients undergoing versus not undergoing pretreatment diagnostic prostate mpMRI. Uni- and multivariable logistic regression evaluated the relationship of clinical and demographic characteristics with MRI utilization.

RESULTS

All demographic variables assessed, except the other race category, were significantly associated with MRI utilization (all P < .05), including age (odds ratio [OR], 0.92), black race (OR, 0.51), poverty (OR, 0.53), closer distance to radiation facility (OR, 1.79), and nonprivate primary insurance (OR, 0.57) on univariable analysis, while clinical stage T3 (OR, 3.37) was the only clinical characteristic. On multivariable analysis stratified by D'Amico risk group, age remained significant across all risk groups, whereas the black versus white racial (OR, 0.21; 95% confidence interval, 0.08-0.55) and nonprivate versus private insurance type (OR, 0.37; 95% confidence interval, 0.16-0.86) disparities persisted in the low-risk group. Clinical stage T3 remained associated in the high-risk group. For race specifically, the percentages of whites, blacks, and others undergoing MRI in the overall cohort and by risk group were, respectively: overall, 80% (343/427), 68% (156/231), and 85% (40/47); low risk, 86%, 56%, and 63%; intermediate risk, 79%, 72%, and 95%; and high risk, 72%, 72%, and 100%.

CONCLUSIONS

In this urban, academic center cohort, older patients across all risk groups and black or nonprivate insurance patients in the low risk group were less likely to undergo staging prostate MRI scans. Further research should investigate these differences to ensure equitable utilization across all demographic groups considering the burden of prostate cancer disparities.

Endorectal MRI for risk classification of localized prostate cancer: Radiographic findings and influence on treatment decisions

PURPOSE

To report the results of endorectal coil magnetic resonance imaging (eMRI) in patients with localized prostate cancer, and how these images influenced radiotherapeutic management.

MATERIALS AND METHODS

A total of 122 men with localized adenocarcinoma of the prostate referred to radiation oncology underwent 3-T eMRI between 2010 and 2014, to evaluate candidacy for active surveillance (n = 26) and brachytherapy as monotherapy (n = 47), or to further risk stratify intermediate-risk (n = 29) or high-risk (n = 20) men before external beam radiation therapy. By National Comprehensive Cancer Network classification, men had low-risk (28%), intermediate-risk (55%), or high-risk (17%) disease. Multiparametric MRI sequences included T2-weighted, diffusion-weighted imaging, and dynamic contrast-enhanced imaging. Radiographic extracapsular extension, seminal vesicle invasion (rSVI), and pelvic lymph node involvement (LNI) were graded as negative, indeterminate, or positive. A dominant nodule was defined as a nodule≥1.5cm. Changes in management were identified comparing pre-MRI and post-MRI plan of care.

RESULTS

The rates of radiographic extracapsular extension, radiographic seminal vesicle invasion, lymph node involvement, and dominant nodule were 39%, 7%, 12%, and 28%, respectively. The eMRI identified measurable disease in most patients with an increasing burden of disease (sextants involved, median nodule size) according to risk category (P<0.01). Changes in management after eMRI occurred in 18%, including 9%, 18%, and 33% of men with low-risk, intermediate-risk, or high-risk disease (P = 0.08), and 12%, 17%, and 22% of men who were candidates for active surveillance, brachytherapy as monotherapy, or external beam radiation therapy (P = 0.48), respectively.

CONCLUSION

The eMRI influenced management in a risk-dependent fashion. Further study is required to determine the clinical importance of eMRI findings and to determine whether changes in management can lead to improved clinical outcome.

Prostate MRSI predicts outcome in radical prostatectomy patients

BACKGROUND

New non-invasive methods are needed for sub-stratifying high-risk prostate cancer patients. Magnetic resonance spectroscopic imaging (MRSI) maps metabolites in prostate cancer, providing information on tumor aggressiveness and volume.

PURPOSE

To investigate the correlation between MRSI and treatment failure (TF) after radical prostatectomy (RP).

METHODS

Two-hundred sixty-two patients who underwent endorectal MRI/MRSI followed by RP at our institution from 2003 to 2007 were studied. MRI stage, number of voxels in the MRSI index lesion (NILV), number of high-grade voxels (NHGV), and number of voxels containing undetectable polyamines (NUPV) were derived. Clinical outcome was followed until August, 2014. Treatment failure was defined as 1) biochemical recurrence (BCR), 2) persistently detectable PSA after RP, or 3) adjuvant therapy initiated in the absence of BCR. MRI/MRSI features and clinical parameters were compared to TF by univariate Cox Proportional Hazards Regression. After backward selection, each MRSI parameter was included in a separate regression model adjusted for NCCN-based clinical risk score (CRS), number of biopsy cores positive (NPC), and MRI stage.

RESULTS

In univariate analysis, all clinical variables were associated with TF in addition to MRI stage, NILV, NHGV, and NUPV. In multivariate analysis, NILV, NHGV, and NUPV were also significant risk factors for TF (p=0.016, p=0.002, p=0.006, respectively). The association between the number of tumor voxels with undetectable polyamines and the probability of treatment failure has not been previously reported. The number of MRSI cancer voxels correlated with extracapsular extension (ECE) (p<0.0001).

CONCLUSIONS

MRSI was associated with post-radical prostatectomy treatment failure in models adjusted for the number of positive biopsy cores and clinical risk score. This is the first report that in radical prostatectomy patients MRSI has an association with treatment failure independent of the number of positive biopsy cores. MRSI may help the clinician determine whether patients with high risk disease who undergo RP are candidates for specialized additional treatment.

Impact of intraoperative MRI/TRUS fusion on dosimetric parameters in cT3a prostate cancer patients treated with high-dose-rate real-time brachytherapy

Purpose

The purpose of this study was to evaluate the impact of intraoperative MRI/TRUS fusion procedure in cT3a prostate cancer patients treated with high-dose-rate (HDR) real-time brachytherapy.

Material and methods

Prostate gland, dominant intraprostatic lesions (DILs), and extracapsular extension (ECE) were delineated in the pre-brachytherapy magnetic resonance images (MRI) of 9 consecutive patients. The pre-implant P-CTV_US (prostate clinical target volume) was defined as the prostate seen in the transrectal ultrasound (TRUS) images. The CTV_MR includedthe prostate with the ECE image (ECE-CTV) as defined on the MRI. Two virtual treatment plans were performed based on the MRI/TRUS fusion images, the first one prescribing 100% of the dose to the P-PTV_US, and the second prescribing to the PTV_MR. The implant parameters and dose-volume histogram (DVH) related parameters of the prostate, OARs, and ECE were compared between both plans.

Results

Mean radial distance of ECE was 3.6 mm (SD: 1.1). No significant differences were found between prostate V₁₀₀, V₁₅₀, V₂₀₀, and OARs DVH-related parameters between the plans. Mean values of ECE V₁₀₀, V₁₅₀, and V₂₀₀ were 85.9% (SD: 15.1), 18.2% (SD: 17.3), and 5.85% (SD: 7) when the doses were prescribed to the PTV_US, whereas ECE V₁₀₀, V₁₅₀, and V₂₀₀ were 99.3% (SD: 1.2), 45.8% (SD: 22.4), and 19.6% (SD: 12.6) when doses were prescribed to PTV_MR (p = 0.028, p = 0.002 and p = 0.004, respectively).

Conclusions

TRUS/MRI fusion provides important information for prostate brachytherapy, allowing for better coverage and higher doses to extracapsular disease in patients with clinical stage T3a.

Prostate cancer at the peripheral end of prostate biopsy specimen predicts increased risk of positive resection margin after radical prostatectomy: results of a prospective multi-institutional study

PURPOSE

To test a novel technique of processing prostate biopsy specimen by marking the peripheral end (PE) as a predictive tool for positive resection margin after radical prostatectomy (RP) or for locally advanced carcinoma of the prostate (PC).

METHODS

Prospective, multi-institutional study of a consecutive cohort of men who underwent prostate biopsy with marking the peripheral biopsy end and subsequent RP at the same institution.

RESULTS

The study cohort comprised 445 men with a mean age of 63 years (40-77 years). Overall, PE-positive cores were found in 174 men (39.1 %) and R1 status was diagnosed in 132 men after RP (29.7 %). In the multivariate analysis, the presence of at least one PE-positive core was correlated with an increased risk of R1 status (OR 2.29, 95 % CI 1.31-4.00, p = 0.003) and was the strongest predictor followed by Gleason score, PSA and percentage of positive cores. Including all predictive parameters, a nomogram with a concordance index of 72.1 % was calculated. In the pT3/pT4 subgroup, PE positivity was the only predictive factor for R1 status (OR 3.03, 95 % CI 1.36-6.75, p = 0.006). In pT2 stage, no single factor was predictive for R1 status. PE-positive biopsies were not predictive for pT3/pT4 stages.

CONCLUSIONS

PC at the peripheral end of prostate biopsy specimen predicts an increased risk of R1 status in subsequent RP. This simple and cheap technique may contribute to an increased accuracy of risk stratification for curative treatment for PC.

Incremental value of magnetic resonance imaging for clinically high risk prostate cancer in 922 radical prostatectomies

PURPOSE

We investigated the incremental value of magnetic resonance imaging in addition to clinical variables for predicting pathological outcomes and disease recurrence in patients with clinically high risk prostate cancer.

MATERIALS AND METHODS

A total of 922 consecutive patients with clinically high risk prostate cancer underwent magnetic resonance imaging before radical prostatectomy. We created multivariate logistic regression and Cox proportional hazards models with clinical variables only or combined with magnetic resonance imaging data to predict pathological outcomes and biochemical recurrence. The models were compared using ROC curves and the Harrell concordance index.

RESULTS

The proportion of patients with pathological extracapsular extension, seminal vesicle invasion and lymph node metastasis was 57.5%, 12.7% and 6.3%, respectively. The sensitivity and specificity of extracapsular extension, seminal vesicle invasion and lymph node metastasis detection were 43% and 84.2%, 34.9% and 93.8%, and 14.0% and 96.9%, respectively. The area under the ROC curve of the model with clinical variable and magnetic resonance imaging data was greater than that of the model with clinical variables alone to predict extracapsular extension and seminal vesicle invasion (0.734 vs 0.697, p=0.001 and 0.750 vs 0.698, p<0.001, respectively). The 5-year biochemical recurrence-free survival rate was 56.1%. To predict biochemical recurrence the concordance index of the multivariate model with clinical variables only and with clinical variables plus magnetic resonance imaging data was 0.563 and 0.599, respectively (p=0.003).

CONCLUSIONS

Magnetic resonance imaging findings have incremental value in addition to clinical variables for predicting pathological outcomes and disease recurrence.

[Multiparametric prostate MRI for follow-up monitoring after radiation therapy]

CLINICAL/METHODICAL ISSUE

Radiation therapy is a therapeutic option with curative intent for patients with prostate cancer. Monitoring of prostate-specific antigen (PSA) values is the current standard of care in the follow-up. Imaging is recommended only for symptomatic patients and/or for further therapeutic options.

STANDARD RADIOLOGICAL METHODS

For detection of local recurrence magnetic resonance imaging (MRI) of the prostate is acknowledged as the method of choice.

PERFORMANCE

Good results for primary diagnosis were found especially in combination with functional techniques, whereas in recurrent prostate cancer only few studies with heterogeneous study design are available for prostate MRI. Furthermore, changes in different MRI modalities due to radiation therapy have been insufficiently investigated to date.

PRACTICAL RECOMMENDATIONS

As the initial results were promising prostate MRI and available therapeutic options for detection of local recurrence should be considered in patients with increased PSA.

Accuracy of preoperative endo-rectal coil magnetic resonance imaging in detecting clinical under-staging of localized prostate cancer

OBJECTIVES

To assess the accuracy of intra-rectal coil magnetic resonance imaging (ER-MRI) for staging early prostate cancer (EPC).

MATERIALS AND METHODS

ER-MRI was performed with the Magnetom Symphony 1.5 Tesla system. ER-MRI and pathology findings were statistically correlated.

RESULTS

One hundred and fifty-four consecutive patients underwent radical prostatectomy (RRP) for EPC (cT1c-2 Nx M0). An average age was 66, mean PSA 11.04 µg/L (median 7.33 µg/L) and mean pathologic Gleason score 6. Pathology detected 97 out of 154 patients (63 %) as EPC and 57 cases (37 %) as extra-prostate extension (EPED) (pT3) with extra-capsular extension (ECE) (pT3a) in 41 (27 %) and seminal vesicle invasion (SVI) (pT3b) in 16 (10 %). ER-MRI staged 100 patients (65 %) as cT2 and 54 (35 %) as EPED with ECE in 37 cases (24 %) and SVI in 17 (11 %). ER-MRI sensitivity, specificity, positive predictive value, negative predictive value, overall accuracy resulted respectively 0.78, 0.96, 0.86, 0.92, 0.91 for ECE as well as 0.88, 0.98, 0.82, 0.99 and 0.97 for SVI.

CONCLUSION

ER-MRI was effective in detecting preoperative EPC under-staging. In the next future, multi-parametric 3-Tesla ER-MRI will be the procedure for diagnosing, staging and following-up prostate cancer patients.

Endorectal MRI of prostate cancer: incremental prognostic importance of gross locally advanced disease

OBJECTIVE

The purpose of this study was to determine the frequency and incremental prognostic importance of gross locally advanced disease seen at endorectal MRI in patients with prostate cancer.

MATERIALS AND METHODS

We retrospectively identified the cases of all patients with biopsy-proven prostate cancer who underwent pretreatment endorectal MRI over a 6-year period (n = 1777). Three experienced radiologists identified by consensus patients with gross locally advanced disease, defined as unequivocal extracapsular extension or unequivocal seminal vesicle invasion. Outcome among these patients was compared with that in a control group without gross locally advanced disease matched by D'Amico risk stratification.

RESULTS

Sixty-six of 1777 (3.7%) patients had gross locally advanced disease. One of 1085 (0.1%) patients had low-risk disease, 25 of 489 (5.1%) had intermediate-risk disease, and 40 of 203 (19.7%) had high-risk disease. Follow-up data were available for 44 of these 66 patients. During a median follow-up period of 79 months, biochemical failure and metastasis had developed in 17 and 6 of these 44 patients compared with 9 and none of the 65 patients in the control group (p < 0.001).

CONCLUSION

Almost 4% of patients with prostate cancer, particularly those with intermediate- and high-risk disease, have gross locally advanced disease at endorectal MRI and have a significantly worse prognosis than matched controls. These patients may be candidates for more aggressive treatment.

Prostate cancer: prediction of biochemical failure after external-beam radiation therapy--Kattan nomogram and endorectal MR imaging estimation of tumor volume

PURPOSE

To determine whether magnetic resonance (MR) imaging and MR spectroscopic imaging findings can improve predictions made with the Kattan nomogram for radiation therapy.

MATERIALS AND METHODS

The institutional review board approved this retrospective HIPAA-compliant study. Ninety-nine men who underwent endorectal MR and MR spectroscopy before external-beam radiation therapy for prostate cancer (January 1998 to June 2007) were included. Linear predictors were calculated with input variables from the study sample and the Kattan original coefficients. The linear predictor is a single weighted value that combines information of all predictor variables in a model, where the weight of each value is its association with the outcome. Two radiologists independently reviewed all MR images to determine extent of disease; a third independent reader resolved discrepancies. Biochemical failure was defined as a serum prostate-specific antigen level of 2 ng/mL (2 μg/L) or more above nadir. Cox proportional hazard models were used to determine the probabilities of treatment failure (biochemical failure) in 5 years. One model included only the Kattan nomogram data; the other also incorporated imaging findings. The discrimination performance of all models was determined with receiver operating characteristics (ROC) curve analyses. These analyses were followed by an assessment of net risk reclassification.

RESULTS

The areas under the ROC curve for the Kattan nomogram and the model incorporating MR imaging findings were 61.1% (95% confidence interval: 58.1%, 64.0%) and 78.0% (95% confidence interval: 75.7%, 80.4%), respectively. Comparison of performance showed that the model with imaging findings performed significantly better than did the model with clinical variables alone (P < .001). Overall, the addition of imaging findings led to an improvement in risk classification of about 28%, ranging from approximately a minimum of 16% to a maximum of 39%, depending on the risk change considered important.

CONCLUSION

MR imaging data improve the prediction of biochemical failure with the Kattan nomogram after external-beam radiation therapy for prostate cancer. The number needed to image to improve the prediction of biochemical failure in one patient ranged from three to six.

Early choline levels from 3-tesla MR spectroscopy after exclusive radiation therapy in patients with clinically localized prostate cancer are predictive of plasmatic levels of PSA at 1 year

PURPOSE

To investigate the time course response of prostate metabolism to irradiation using magnetic resonance spectroscopy (MRS) at 3-month intervals and its impact on biochemical control.

METHODS AND MATERIALS

Between January 2008 and April 2010, 24 patients with localized prostate cancer were prospectively enrolled in the Evaluation of the Response to Irradiation with MR Spectroscopy (ERIS) trial. All the patients had been treated with intensity-modulated radiation therapy with or without long-term adjuvant hormonal therapy (LTHT) and underwent 3-T MRS and prostate-specific antigen (PSA) assays at baseline and every 3 months thereafter up to 12 months.

RESULTS

After radiation, the mean normalized citrate level (citrate/water) decreased significantly over time, both in the peripheral zone (PZ) (p = 0.0034) and in the entire prostate (p = 0.0008), whereas no significant change was observed in mean normalized choline levels (choline/water) in the PZ (p = 0.84) and in the entire prostate (p = 0.95). At 6 months after radiation, the mean choline level was significantly lower in the PZ for patients with a PSA value of ≤0.5 ng/mL at 12 months (4.9 ± 1.7 vs. 7.1 ± 1.5, p = 0.0378). Similar results were observed at 12 months in the PZ (6.2 ± 2.3 vs. 11.4 ± 4.1, p = 0.0117 for choline level and 3.4 ± 0.7 vs. 16.1 ± 6.1, p = 0.0054 for citrate level) and also in the entire prostate (6.2 ± 1.9 vs. 10.4 ± 3.2, p = 0.014 for choline level and 3.0 ± 0.8 vs. 13.3 ± 4.7, p = 0.0054 for citrate level). For patients receiving LTHT, there was no correlation between choline or citrate levels and PSA value, either at baseline or at follow-up.

CONCLUSIONS

Low normalized choline in the PZ, 6 months after radiation, predicts which patients attained a PSA ≤0.5 ng/mL at 1 year. Further analyses with longer follow-up times are warranted to determine whether or not these new biomarkers can conclusively predict the early radiation response and the clinical outcome for patients with or without LTHT.

Metabolic tumor imaging using magnetic resonance spectroscopy

The adaptability and the genomic plasticity of cancer cells, and the interaction between the tumor microenvironment and co-opted stromal cells, coupled with the ability of cancer cells to colonize distant organs, contribute to the frequent intractability of cancer. It is becoming increasingly evident that personalized molecular targeting is necessary for the successful treatment of this multifaceted and complex disease. Noninvasive imaging modalities such as magnetic resonance (MR), positron emission tomography (PET), and single-photon emission computed tomography (SPECT) are filling several important niches in this era of targeted molecular medicine, in applications that span from bench to bedside. In this review we focus on noninvasive magnetic resonance spectroscopy (MRS) and spectroscopic imaging (MRSI) and their roles in future personalized medicine in cancer. Diagnosis, the identification of the most effective treatment, monitoring treatment delivery, and response to treatment are some of the broad areas into which MRS techniques can be integrated to improve treatment outcomes. The development of novel probes for molecular imaging--in combination with a slew of functional imaging capabilities--makes MRS techniques, especially in combination with other imaging modalities, valuable in cancer drug discovery and basic cancer research.

Imaging in prostate cancer

Prostate cancer is the most common malignancy in men, in general. Most patients diagnosed with prostate cancer have localized disease confined to the prostate. A small percentage of patients with aggressive tumors will progress to develop local, extracapsular tumor extension and distant metastases. The aim of prostate cancer management is to identify and treat those patients with aggressive disease before they develop locally advanced or metastatic disease, and to avoid overtreating indolent tumors, which are unlikely to be life threatening. Imaging has been shown to be valuable in local staging of prostate cancer and as an aid to the management of clinically significant disease. In this article, we discuss the different established imaging modalities and emerging techniques for prostate cancer imaging in patients with clinically localized disease who may be suitable for radical treatment.

Are histopathological features of prostate cancer lesions associated with identification of extracapsular extension on magnetic resonance imaging?

OBJECTIVE

To assess the effect of histopathological lesion characteristics on the sensitivity of magnetic resonance imaging (MRI) for per-lesion identification of extracapsular extension (ECE) of prostate cancer.

PATIENTS AND METHODS

The study included 176 patients (median age 58.9 years, range 38-77) who underwent endorectal MRI before radical prostatectomy between January 2001 and July 2004, had no previous treatment and had whole-mount step-section pathological specimens showing at least one capsule-abutting lesion. The likelihood of ECE of capsule-abutting lesions was retrospectively scored from 1 to 5 based on radiologists' prospective MRI interpretations. Generalized estimating equation regression models were used to determine the effect of the following histological variables on the sensitivity of MRI for identifying ECE of capsule-abutting lesions: maximum diameter, largest perpendicular diameter (LPD), bi-dimensional diameter product, Gleason grade, and zonal extent.

RESULTS

On histopathology, 339 capsule-abutting lesions were found, including 54 with ECE. MRI correctly identified ECE in 36/54 capsule-abutting lesions, including nine of 18 with focal ECE and 27/36 with established ECE, giving sensitivities (95% confidence interval) of 67 (53-78)%, 50 (27-73)% and 75 (58-87)%, respectively. MRI incorrectly identified ECE in 27/285 (9%) capsule-abutting lesions without ECE. MRI sensitivity for per-lesion ECE identification was significantly associated only with histopathological LPD (P = 0.009). Fifty-one patients (29%) had ECE. MRI had a sensitivity (95% confidence interval) of 69 (54-81)% and specificity of 90 (83-94)% for per-patient ECE identification.

CONCLUSIONS

The sensitivity of MRI in per-lesion identification of prostate cancer ECE is significantly associated with the lesion LPD at histopathology.

Prostate cancer at the peripheral end of a prostate biopsy specimen as assessed by a novel marking technique may indicate increased risk of locally advanced disease

The objective of this study was to test a novel technique of processing a prostate biopsy (PB) specimen by marking its peripheral end (PE) as a predictive tool for locally advanced prostate cancer (PC) or margin-positive resection (R1) after radical prostatectomy (RP). Prospective evaluation of a consecutive cohort of men who underwent PB and subsequent RP was carried out. Transrectal ultrasound-guided 10-20 core PB was performed according to a standardized protocol. Each biopsy core was inked at the PE and classified as PE positive or negative. The study cohort comprised 100 men with a mean age of 62.3 years (41-75 years). Overall, PE-positive cores were found in 71 men, postoperative tumour (pT)3/pT4 stages were diagnosed in 33 men and R1 status in 45 men after RP. In univariate analysis, the presence of at least one PE-positive core was correlated to an increased risk for pT3/pT4 stage (relative risk (RR): 3.15; 95% confidence interval (95% CI): 1.1-9.9; P = 0.03) and R1 status (RR: 2.9; 95% CI: 1.1-7.5; P = 0.03). In multivariate analysis including Gleason score, total number of positive cores, PE positivity and PSA, PE positivity was correlated to pT3/pT4 stage (P = 0.04). In conclusion, PC at the PE of a PB specimen predicts non-organ-confined tumour stage in subsequent prostatectomy. This simple, new technique may contribute to increasing the accuracy of risk stratification for curative treatment of PC.

An exploratory study of endorectal magnetic resonance imaging and spectroscopy of the prostate as preoperative predictive biomarkers of biochemical relapse after radical prostatectomy

PURPOSE

Radical prostatectomy has significant side effects. Preoperative information predicting its long-term outcome would be valuable to patients and physicians. We determined whether pretreatment endorectal magnetic resonance imaging/magnetic resonance spectroscopic imaging predicts biochemical recurrence after radical prostatectomy.

MATERIALS AND METHODS

Of 202 patients who underwent endorectal magnetic resonance imaging/magnetic resonance spectroscopic imaging from January 2000 to December 2002 before radical prostatectomy 130 satisfied study inclusion criteria and were included in analysis. We compared imaging factors with potential predictive capability to biochemical recurrence data, including magnetic resonance imaging risk score based on local disease extent and magnetic resonance spectroscopic imaging index lesion characteristics, such as the number of voxels and degree of metabolic abnormality (magnetic resonance spectroscopic imaging grade). We evaluated associations of these imaging variables with time to biochemical recurrence by Cox proportional hazards regression adjusted for known predictors of biochemical recurrence, such as stage, grade and prostate specific antigen.

RESULTS

At a median 68-month followup there were 26 biochemical failures. Risk score, lesion volume and high grade voxels each correlated with time to biochemical recurrence. In a model combining clinical parameters risk score, lesion volume and at least 1 high grade voxel the magnetic resonance spectroscopic imaging variables remained significant but the magnetic resonance imaging score dropped out.

CONCLUSIONS

Index lesion volume on magnetic resonance spectroscopic imaging and high grade magnetic resonance spectroscopic imaging voxels correlate with time to biochemical recurrence after radical prostatectomy even when adjusted for clinical data. Results suggest the preoperative predictive usefulness of endorectal magnetic resonance imaging/magnetic resonance spectroscopic imaging in patients considering radical prostatectomy.

Tumor volume and metabolism of prostate cancer determined by proton magnetic resonance spectroscopic imaging at 3T without endorectal coil reveal potential clinical implications in the context of radiation oncology

PURPOSE

To determine whether a relationship exists between the tumor volume (TV) or relative choline content determined using magnetic resonance spectroscopy imaging (MRSI) at 3T and the clinical prognostic parameters for patients with localized prostate cancer (PCa).

METHODS AND MATERIALS

A total of 72 men (mean age, 67.8 ± 6.2 years) were stratified as having low-risk (n = 26), intermediate-risk (n = 24), or high-risk (n = 22) PCa. MRSI was performed at 3T using a phased-array coil. Spectra are expressed as the total choline/citrate, total choline plus creatine/citrate, and total choline plus polyamines plus creatine/citrate ratios. The mean ratio of the most pathologic voxels and the MRSI-based TV were also determined.

RESULTS

The mean values of the total choline/citrate, total choline plus creatine/citrate, and total choline plus polyamine plus creatine/citrate ratios were greater for Stage T2b or greater tumors vs. Stage T2a or less tumors: 7.53 ± 13.60 vs. 2.31 ± 5.65 (p = .018), 8.98 ± 14.58 vs. 2.56 ± 5.70 (p = .016), and 10.32 ± 15.47 vs. 3.55 ± 6.16 (p = .014), respectively. The mean MRSI-based TV for Stage T2b or greater and Stage T2a or less tumors was significantly different (2.23 ± 2.62 cm(3) vs. 1.26 ± 2.06 cm(3), respectively; p = .030). This TV correlated with increased prostate-specific antigen levels (odds ratio, 1.293; p = .012). Patients with high-risk PCa had a larger TV than did the patients with intermediate-risk PCa. A similar result was found for the intermediate-risk group compared with the low-risk group (odds ratio, 1.225; p = .041).

CONCLUSION

Biomarkers expressing the relative choline content and TV were significant parameters for the localization of PCa and could be helpful for determining the prognosis more accurately.

Predicting post-external beam radiation therapy PSA relapse of prostate cancer using pretreatment MRI

PURPOSE

To investigate whether pretreatment endorectal magnetic resonance imaging (MRI) findings can predict biochemical relapse in patients with clinically localized prostate cancer treated with external beam radiation therapy (EBRT).

METHODS AND MATERIALS

Between January 2000 and January 2002, 224 patients (median age, 69 years; age range, 45-82 years) with biopsy-proven prostate cancer underwent endorectal MRI before high-dose (≥81Gy) EBRT. The value of multiple clinical and MRI variables in predicting prostate-specific antigen (PSA) relapse at 5 years was determined by use of univariate and multivariate stepwise Cox regression. Clinical variables included pretreatment PSA, clinical T stage, Gleason score, use of neoadjuvant hormonal therapy, and radiation dose. Magnetic resonance imaging variables, derived from retrospective consensus readings by two radiologists, were used to measure intraprostatic and extraprostatic tumor burden.

RESULTS

After a median follow-up of 67 months, PSA relapse developed in 37 patients (16.5%). The significant predictors of PSA relapse on univariate analysis were pretreatment PSA, clinical T stage, and multiple MRI variables, including MRI TN stage score; extracapsular extension (ECE) status; number of sextants involved by ECE, all lesions, or index (dominant) lesion; apical involvement; and diameter and volume of index lesion. Pretreatment PSA and ECE status were the only significant independent predictors on multivariate analysis (p < 0.05 for both). Extracapsular extension status was associated with the highest hazard ratio, 3.04; 5-year PSA relapse rates were 7% for no ECE, 20% for unilateral ECE, and 48% for bilateral ECE.

CONCLUSIONS

Magnetic resonance imaging findings can be used to predict post-EBRT PSA relapse, with ECE status on MRI and pretreatment PSA being significant independent predictors of this endpoint.

Incremental value of magnetic resonance imaging in the advanced management of prostate cancer

Prostate cancer is a major public health burden throughout the world. The high incidence of prostate cancer, combined with earlier detection and downstaging at the time of diagnosis, and the slow natural progression and biological heterogeneity of the disease, has made its management a complex and controversial issue. There is growing demand for patient-specific therapies that can minimize treatment morbidity while maximizing treatment benefits. There are a number of clinical parameters and clinical nomograms to help with the choice of treatment. Magnetic resonance imaging (MRI) is a technique which makes safer, more individualized therapies possible due to high spatial resolution, superior contrast resolution, multiplanar capability, and a large field of view. Other MRI techniques such as MR spectroscopic imaging, dynamic contrast-enhanced MRI or perfusion MRI, and diffusion-weighted imaging complement MRI by reflecting tissue biochemistry, Brownian motion of water molecules, and capillary wall permeability, respectively. This editorial review highlights the incremental value of MRI in the advanced management of prostate cancer to non-invasively improve cancer staging, biologic potential, treatment planning, therapy response, local recurrence, and to guide target biopsy for clinical suspected cancer with previous negative biopsy. Finally, some future prospects for MRI in prostate cancer management are given.

Imaging localized prostate cancer: current approaches and new developments

OBJECTIVE

Prostate cancer is the most common noncutaneous malignancy among men in the Western world. Imaging has recently become more important in the diagnosis, local staging, and treatment follow-up of prostate cancer. In this article, we review conventional and functional imaging methods as well as targeted imaging approaches with novel tracers used in the diagnosis and staging of prostate cancer.

CONCLUSION

Although prostate cancer is the second leading cause of cancer death in men, imaging of localized prostate cancer remains limited. Recent developments in imaging technologies, particularly MRI and PET, may lead to significant improvements in lesion detection and staging.

Imaging techniques for prostate cancer: implications for focal therapy

The multifocal nature of prostate cancer has necessitated whole-gland therapy in the past; however, since the widespread use of PSA screening, patients frequently present with less-advanced disease. Many men with localized disease wish to avoid the adverse effects of whole-gland therapy; therefore, focal therapy for prostate cancer is being considered as a treatment option. For focal treatment to be viable, accurate imaging is required for diagnosis, staging, and monitoring of treatment. Developments in MRI and PET have brought more attention to prostate imaging and the possibility of improving the accuracy of focal therapy. In this Review, we discuss the advantages and disadvantages of conventional methods for imaging the prostate, new developments for targeted imaging, and the possible role of image-guided biopsy and therapy for localized prostate cancer.