MRI-Ultrasound Fused Approach for Prostate Biopsy-How It Is Performed

The use of MRI-ultrasound image fusion targeted biopsy of the prostate in the face of an elevated serum PSA is now recommended by multiple societies, and results in improved detection of clinically significant cancer and, potentially, decreased detection of indolent disease. This combines the excellent sensitivity of MRI for clinically significant prostate cancer and the real-time biopsy guidance and confirmation of ultrasound. Both transperineal and transrectal approaches can be implemented using cognitive fusion, mechanical fusion with an articulated arm and electromagnetic registration, or pure software registration. The performance has been shown comparable to in-bore MRI biopsy performance. However, a number of factors influence the performance of this technique, including the quality and interpretation of the MRI, the approach used for biopsy, and experience of the practitioner, with most studies showing comparable performance of MRI-ultrasound fusion to in-bore targeted biopsy. Future improvements including artificial intelligence promise to refine the performance of all approaches.

Interpretation of Prostate Magnetic Resonance Imaging Using Prostate Imaging and Data Reporting System Version 2.1: A Primer

Prostate magnetic resonance imaging (MRI) is increasingly being used to diagnose and stage prostate cancer. The Prostate Imaging and Data Reporting System (PI-RADS) version 2.1 is a consensus-based reporting system that provides a standardized and reproducible method for interpreting prostate MRI. This primer provides an overview of the PI-RADS system, focusing on its current role in clinical interpretation. It discusses the appropriate use of PI-RADS and how it should be applied by radiologists in clinical practice to assign and report PI-RADS assessments. We also discuss the changes from prior versions and published validation studies on PI-RADS accuracy and reproducibility.

Management of Patients With a Negative Multiparametric Prostate MRI Examination: AJR Expert Panel Narrative Review

Multiparametric prostate MRI (mpMRI) aids risk stratification of patients with elevated PSA levels. While most clinically significant prostate cancers are detected by mpMRI, insignificant cancers are less evident. Thus, multiple international prostate cancer guidelines now endorse routine use of prostate MRI as a secondary screening test before prostate biopsy. Nonetheless, management of patients with negative mpMRI results (defined as PI-RADS category 1 or 2) remains unclear. This AJR Expert Panel Narrative Review summarizes the available literature on patients with an elevated screening PSA level and a negative prostate mpMRI, and provides guidance for these patients' management. Systematic biopsy should not be routinely performed after a negative mpMRI in patients at average risk but should be considered in patients at high risk. In patients who undergo PSA screening rather than systematic biopsy after negative mpMRI, clear triggers should be established for when to perform a repeat MRI. Patients with negative MRI followed by negative biopsy should follow their healthcare practitioners' preferred guidelines concerning subsequent PSA screening for the patient's risk level. Insufficient high-level data exist to support routine use of adjunctive serum or urine biomarkers, artificial intelligence, or PSMA PET to determine the need for prostate biopsy after negative mpMRI.

The role of AI in prostate MRI quality and interpretation: Opportunities and challenges

Prostate MRI plays an important role in imaging the prostate gland and surrounding tissues, particularly in the diagnosis and management of prostate cancer. With the widespread adoption of multiparametric magnetic resonance imaging in recent years, the concerns surrounding the variability of imaging quality have garnered increased attention. Several factors contribute to the inconsistency of image quality, such as acquisition parameters, scanner differences and interobserver variabilities. While efforts have been made to standardize image acquisition and interpretation via the development of systems, such as PI-RADS and PI-QUAL, the scoring systems still depend on the subjective experience and acumen of humans. Artificial intelligence (AI) has been increasingly used in many applications, including medical imaging, due to its ability to automate tasks and lower human error rates. These advantages have the potential to standardize the tasks of image interpretation and quality control of prostate MRI. Despite its potential, thorough validation is required before the implementation of AI in clinical practice. In this article, we explore the opportunities and challenges of AI, with a focus on the interpretation and quality of prostate MRI.

Pulse Sequence Dependence of a Simple and Interpretable Deep Learning Method for Detection of Clinically Significant Prostate Cancer Using Multiparametric MRI

RATIONALE AND OBJECTIVES

Multiparametric magnetic resonance imaging (mpMRI) is increasingly used for risk stratification and localization of prostate cancer (PCa). Thanks to the great success of deep learning models in computer vision, the potential application for early detection of PCa using mpMRI is imminent.

MATERIALS AND METHODS

Deep learning analysis of the PROSTATEx dataset.

RESULTS

In this study, we show a simple convolutional neural network (CNN) with mpMRI can achieve high performance for detection of clinically significant PCa (csPCa), depending on the pulse sequences used. The mpMRI model with T2-ADC-DWI achieved 0.90 AUC score in the held-out test set, not significantly better than the model using K^trans instead of DWI (AUC 0.89). Interestingly, the model incorporating T2-ADC- K^trans better estimates grade. We also describe a saliency "heat" map. Our results show that csPCa detection models with mpMRI may be leveraged to guide clinical management strategies.

CONCLUSION

Convolutional neural networks incorporating multiple pulse sequences show high performance for detection of clinically-significant prostate cancer, and the model including dynamic contrast-enhanced information correlates best with grade.

Pilot study of the diagnostic utility of 89 Zr-df-IAB2M and 68 Ga-PSMA-11 PET imaging and multiparametric MRI in localized prostate cancer

BACKGROUND

Accurate diagnosis of localized prostate cancer (PCa) is limited by inadequacy of multiparametric (mp) MRI to fully identify and differentiate localized malignant tissue from benign pathologies. Prostate-specific membrane antigen (PSMA) represents an excellent target for molecular imaging. IAB2M, an 85-kD minibody derived from a de-immunized monoclonal antibody directed at the extracellular domain of human PSMA (huJ591), and PSMA-11, a small molecule ligand have been previously tested as probes for visualization of recurrent/metastatic PCa with PET/CT. This pilot, non-randomized trial studied their diagnostic utility in patients (pts) with localized PCa.

METHODS

Pts planned for radical prostatectomy (RP) were enrolled and underwent mpMRI and PET/CT imaging with ⁸⁹ Zr-df-IAB2M and/or ⁶⁸ Ga-PSMA-PET/CT. Image results were read by a radiologist blinded to clinical information and pathology results, mapped and compared to corresponding histopathology findings from all lesions, both clinically significant and nonsignificant. The detection rates of all three imaging modalities were measured and correlated.

RESULTS

20 pts with median age of 64.5 (46-79) years and PSA level of 7.5 (1.6-36.56) ng/ml were enrolled. 19 pts underwent RP and were imaged pre-operatively with ⁸⁹ Zr-Df-IAB2M PET/CT and mpMRI. Nine of those were imaged using ⁶⁸ Ga-PSMA-11 as well. Out of 48 intraprostatic lesions verified on surgical pathology, IAB2M PET/CT was able to detect 36 (75%). A similar proportion of pathologically confirmed, clinically significant lesions (22/29, 76%) was detected. IAB2M PET/CT was also able to identify 14/19 (74%) extraprostatic lesions. The performance of mpMRI was inferior, with 24/48 detectable lesions (50%) and 18/29 clinically significant intraprostatic lesions (62%). Compared to the current standard (mpMRI), IAB2M PET/CT had a sensitivity of 88%, specificity 38%, positive predictive value 58%, and accuracy 63%. In 9 pts who underwent Ga-PSMA-11 as well, the latter yielded a detection rate of 70% (14/20), which was also seen in clinically significant lesions (10/14, 71%). Ga-PSMA-11 PET/CT also detected 4/6 (67%) extraprostatic lesions.

CONCLUSIONS

In this pilot study, the performance of ⁸⁹ Zr-df-IAB2M was superior to mpMRI and similar to ⁶⁸ Ga-PSMA-11 PET/CT. The higher detection rate of PSMA-PET supports its use as a diagnostic tool with consequent management change implications in men with localized PCa.

Magnetic Resonance Imaging Radiomics-Based Machine Learning Prediction of Clinically Significant Prostate Cancer in Equivocal PI-RADS 3 Lesions

BACKGROUND

While Prostate Imaging Reporting and Data System (PI-RADS) 4 and 5 lesions typically warrant prostate biopsy and PI-RADS 1 and 2 lesions may be safely observed, PI-RADS 3 lesions are equivocal.

PURPOSE

To construct and cross-validate a machine learning model based on radiomics features from T₂ -weighted imaging (T₂ WI) of PI-RADS 3 lesions to identify clinically significant prostate cancer (csPCa), that is, pathological Grade Group ≥ 2.

STUDY TYPE

Single-center retrospective study.

POPULATION

A total of 240 patients were included (training cohort, n = 188, age range 43-82 years; test cohort, n = 52, age range 41-79 years). Eligibility criteria were 1) magnetic resonance imaging (MRI)-targeted biopsy between 2015 and 2020; 2) PI-RADS 3 index lesion identified on multiparametric MRI; (3) biopsy performed within 1 year of MRI. The percentages of csPCa lesions were 10.6% and 15.4% in the training and test cohorts, respectively.

FIELD STRENGTH/SEQUENCE

A 3 T; T₂ WI turbo-spin echo, diffusion-weighted spin-echo echo planar imaging, dynamic contrast-enhanced MRI with time-resolved T1-weighted imaging.

ASSESSMENT

Multislice volumes-of-interest (VOIs) were drawn in the PI-RADS 3 index lesions on T₂ WI. A total of 107 radiomics features (first-order histogram and second-order texture) were extracted from the segmented lesions.

STATISTICAL TESTS

A random forest classifier using the radiomics features as input was trained and validated for prediction of csPCa. The performance of the machine learning classifier, prostate specific antigen (PSA) density, and prostate volume for csPCa prediction was evaluated using receiver operating characteristic (ROC) analysis.

RESULTS

The trained random forest classifier constructed from the T₂ WI radiomics features good and statistically significant area-under-the-curves (AUCs) of 0.76 (P = 0.022) for prediction of csPCa in the test set. Prostate volume and PSA density showed moderate and nonsignificant performance (AUC 0.62, P = 0.275 and 0.61, P = 0.348, respectively) for csPCa prediction in the test set.

CONCLUSION

The machine learning classifier based on T₂ WI radiomic features demonstrated good performance for prediction of csPCa in PI-RADS 3 lesions.

EVIDENCE LEVEL

4 TECHNICAL EFFICACY: 2.

Multivariate analysis of CT imaging, laboratory, and demographical features for prediction of acute kidney injury in COVID-19 patients: a Bi-centric analysis

PURPOSE

To develop and externally validate a multivariate prediction model for the prediction of acute kidney injury (AKI) in COVID-19, based on baseline renal perfusion from contrast-enhanced CT together with clinical and laboratory parameters.

METHODS

In this retrospective IRB-approved study, we identified COVID-19 patients who had a standard-of-care contrast-enhanced abdominal CT scan within 5 days of their COVID-19 diagnosis at our institution (training set; n = 45, mean age 65 years, M/F 23/22) and at a second institution (validation set; n = 41, mean age 61 years, M/F 22/19). The CT renal perfusion parameter, cortex-to-aorta enhancement index (CAEI), was measured in both sets. A multivariate logistic regression model for predicting AKI was constructed from the training set with stepwise feature selection with CAEI together with demographical and baseline laboratory/clinical data used as input variables. Model performance in the training and validation set was evaluated with ROC analysis.

RESULTS

AKI developed in 16 patients (35.6%) of the training set and in 6 patients (14.6%) of the validation set. Baseline CAEI was significantly lower in the patients that ultimately developed AKI (P = 0.003). Logistic regression identified a model combining baseline CAEI, blood urea nitrogen, and gender as most significant predictor of AKI. This model showed excellent diagnostic performance for prediction of AKI in the training set (AUC = 0.89, P < 0.001) and good performance in the validation set (AUC 0.78, P = 0.030).

CONCLUSION

Our results show diminished renal perfusion preceding AKI and a promising role of CAEI, combined with laboratory and demographic markers, for prediction of AKI in COVID-19.

PI-RADS: what is new and how to use it

The prostate imaging reporting and data system (PI-RADS) has revolutionized the use of magnetic resonance imaging (MRI) for the management of prostate cancer (PCa). The most recent version 2.1, PI-RADS v2.1, provides specific refinements in the performance, relaxing some recommendations which were not found to be helpful, while reinforcing and clarifying others. The interpretation of T2-weighted imaging (T2WI) in the transition zone (TZ), and the overall assessment of TZ nodules, now allows for a clearer distinction between those which are clearly benign and those which might warrant tissue sampling. Additional changes also resolve discrepancies in T2WI and diffusion-weighted imaging (DWI) of the peripheral zone (PZ). PI-RADS v2.1 is a simpler, more straightforward, and more reproducible method to better communicate between physicians regarding findings on prostate MRI.

Prostate MRI with PI-RADS v2.1: initial detection and active surveillance

The role of prostate MRI in clinical practice has continued to broaden over time. Multiple iterations of PI-RADS reporting have aided in improving detection and reporting of prostate cancer. In addition, recent recommendations from the PI-RADS Steering Committee promote an MRI-first approach with an MRI-directed prostate cancer diagnostic pathway. It is imperative for radiologists to be knowledgeable and familiar with prostate MRI and PI-RADS recommendations, as there is an increasing demand for prostate imaging by clinicians and patients alike.

Variability of the Positive Predictive Value of PI-RADS for Prostate MRI across 26 Centers: Experience of the Society of Abdominal Radiology Prostate Cancer Disease-focused Panel

Background Prostate MRI is used widely in clinical care for guiding tissue sampling, active surveillance, and staging. The Prostate Imaging Reporting and Data System (PI-RADS) helps provide a standardized probabilistic approach for identifying clinically significant prostate cancer. Despite widespread use, the variability in performance of prostate MRI across practices remains unknown. Purpose To estimate the positive predictive value (PPV) of PI-RADS for the detection of high-grade prostate cancer across imaging centers. Materials and Methods This retrospective cross-sectional study was compliant with the HIPAA. Twenty-six centers with members in the Society of Abdominal Radiology Prostate Cancer Disease-focused Panel submitted data from men with suspected or biopsy-proven untreated prostate cancer. MRI scans were obtained between January 2015 and April 2018. This was followed with targeted biopsy. Only men with at least one MRI lesion assigned a PI-RADS score of 2-5 were included. Outcome was prostate cancer with Gleason score (GS) greater than or equal to 3+4 (International Society of Urological Pathology grade group ≥2). A mixed-model logistic regression with institution and individuals as random effects was used to estimate overall PPVs. The variability of observed PPV of PI-RADS across imaging centers was described by using the median and interquartile range. Results The authors evaluated 3449 men (mean age, 65 years ± 8 [standard deviation]) with 5082 lesions. Biopsy results showed 1698 cancers with GS greater than or equal to 3+4 (International Society of Urological Pathology grade group ≥2) in 2082 men. Across all centers, the estimated PPV was 35% (95% confidence interval [CI]: 27%, 43%) for a PI-RADS score greater than or equal to 3 and 49% (95% CI: 40%, 58%) for a PI-RADS score greater than or equal to 4. The interquartile ranges of PPV at these same PI-RADS score thresholds were 27%-44% and 27%-48%, respectively. Conclusion The positive predictive value of the Prostate Imaging and Reporting Data System was low and varied widely across centers. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Milot in this issue.

Components of Radiologic Progressive Disease Defined by RECIST 1.1 in Patients with Metastatic Clear Cell Renal Cell Carcinoma

Background Progression-free survival (PFS) determined by Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST 1.1) is the reference standard to assess efficacy of treatments in patients with clear cell renal cell carcinoma. Purpose To assess the most common components of radiologic progressive disease as defined by RECIST 1.1 in patients with clear cell renal cell carcinoma and how the progression events impact PFS. Materials and Methods This secondary analysis of the phase III METEOR trial conducted between 2013 and 2014 included patients with metastatic clear cell renal cell carcinoma, with at least one target lesion at baseline and one follow-up time point, who were determined according to RECIST 1.1 to have progressive disease. A chest, abdominal, and pelvic scan were acquired at each time point. Kruskal-Wallis analysis was used to test differences in median PFS among the RECIST 1.1 progression events. The Holm-Bonferroni method was used to compare the median PFS of the progression events for the family-wise error rate of 5% to adjust P values for multiple comparisons. Results Of the 395 patients (296 men, 98 women, and one patient with sex not reported; mean age, 61 years ± 10), 73 (18.5%) had progression due to non-target disease, 105 (26.6%) had new lesions, and 126 (31.9%) had progression of target lesions (defined by an increase in the sum of diameters). Patients with progression of non-target disease and those with new lesions had shorter PFS than patients with progression defined by the target lesions (median PFS, 2.8 months [95% confidence interval {CI}: 1.9 months, 3.7 months] and 3.6 months [95% CI: 3.3 months, 3.7 months] vs 5.4 months [95% CI: 5.0 months, 5.5 months], respectively [P < .01]). Conclusion The most common causes for radiologic progression of renal cell carcinoma were based on non-target disease and new lesions rather than change in target lesions, despite this being considered uncommon in the Response Evaluation Criteria in Solid Tumors version 1.1 literature. © RSNA, 2019 See also the editorial by Kuhl in this issue.

Building a high-resolution T2-weighted MR-based probabilistic model of tumor occurrence in the prostate

PURPOSE

We present a method for generating a T2 MR-based probabilistic model of tumor occurrence in the prostate to guide the selection of anatomical sites for targeted biopsies and serve as a diagnostic tool to aid radiological evaluation of prostate cancer.

MATERIALS AND METHODS

In our study, the prostate and any radiological findings within were segmented retrospectively on 3D T2-weighted MR images of 266 subjects who underwent radical prostatectomy. Subsequent histopathological analysis determined both the ground truth and the Gleason grade of the tumors. A randomly chosen subset of 19 subjects was used to generate a multi-subject-derived prostate template. Subsequently, a cascading registration algorithm involving both affine and non-rigid B-spline transforms was used to register the prostate of every subject to the template. Corresponding transformation of radiological findings yielded a population-based probabilistic model of tumor occurrence. The quality of our probabilistic model building approach was statistically evaluated by measuring the proportion of correct placements of tumors in the prostate template, i.e., the number of tumors that maintained their anatomical location within the prostate after their transformation into the prostate template space.

RESULTS

Probabilistic model built with tumors deemed clinically significant demonstrated a heterogeneous distribution of tumors, with higher likelihood of tumor occurrence at the mid-gland anterior transition zone and the base-to-mid-gland posterior peripheral zones. Of 250 MR lesions analyzed, 248 maintained their original anatomical location with respect to the prostate zones after transformation to the prostate.

CONCLUSION

We present a robust method for generating a probabilistic model of tumor occurrence in the prostate that could aid clinical decision making, such as selection of anatomical sites for MR-guided prostate biopsies.

Focal Therapy Eligibility Determined by Magnetic Resonance Imaging/Ultrasound Fusion Biopsy

PURPOSE

We assessed focal therapy eligibility in men who underwent multiparametric magnetic resonance imaging and targeted biopsy with correlation to whole mount histology after radical prostatectomy.

MATERIALS AND METHODS

Subjects were selected from among the 454 men in whom targeted biopsy proven prostate cancer was derived from regions of interest on multiparametric magnetic resonance imaging from 2010 to 2016. Focal therapy eligibility was limited to a maximum Gleason score of 4 + 3 in regions of interest with or without other foci of low risk prostate cancer (Gleason score 3 + 3 and less than 4 mm). Men who did not meet NCCN® intermediate risk criteria were classified as ineligible for focal therapy. Of the 454 men 64 underwent radical prostatectomy and biopsy findings were compared to final pathology findings.

RESULTS

Of the 454 men with a biopsy proven region of interest 175 (38.5%) were eligible for focal therapy. Fusion biopsy, which combined targeted and template biopsy, had 80.0% sensitivity (12 of 15 cases), 73.5% specificity (36 of 49) and 75.0% accuracy (48 of 64) for focal therapy eligibility. Targeted cores alone yielded 73.3% sensitivity (11 of 15 cases), 47.9% specificity (23 of 48) and 54.7% accuracy (35 of 64). Gleason score and extension across the midline differed in 4 and 9, respectively, of the 13 cases that showed discordant biopsy and whole mount histology.

CONCLUSIONS

Using intermediate risk eligibility criteria more than a third of men with a targeted biopsy proven lesion identified on multiparametric magnetic resonance imaging would have been eligible for focal therapy. Eligibility determined by fusion biopsy was concordant with whole mount histology in 75% of cases. Improved selection criteria are needed to reliably determine focal therapy eligibility.

Sarcomatoid Renal Cell Carcinoma and Collecting Duct Carcinoma: Discrimination From Common Renal Cell Carcinoma Subtypes and Benign RCC Mimics on Multiphasic MDCT

RATIONALE AND OBJECTIVES

To investigate whether imaging features on multiphasic multidetector computed tomography (MDCT) can help discriminate sarcomatoid renal cell carcinoma (RCC) and collecting duct carcinoma (CDC) from other solid renal masses.

MATERIALS AND METHODS

With institutional review board approval for this HIPAA-compliant study, we derived a cohort of 7 sarcomatoid RCCs, 4 CDCs, 165 clear cell RCCs, 56 papillary RCCs, 22 chromophobe RCCs, 49 oncocytomas, and 16 lipid-poor angiomyolipomas with preoperative multiphasic MDCT with up to four phases (unenhanced, corticomedullary, nephrographic, and excretory). Each lesion was reviewed for contour, spread pattern, pattern of enhancement, neovascularity, and calcification.

RESULTS

Sarcomatoid RCCs and CDCs were more likely than other solid renal masses to have an irregular contour (64% vs 2%, P < 0.001) and an infiltrative spread pattern, defined as infiltration into adjacent renal parenchyma, collecting system, or neighboring structures (82% vs 7%, P < 0.001). When used to discriminate sarcomatoid RCC and CDC from other solid renal masses, an infiltrative spread pattern had a specificity of 93% (287/308) and sensitivity of 82% (9/11), and an irregular contour had a specificity of 98% (303/308) and sensitivity of 64% (7/11).

CONCLUSIONS

Solid renal lesions with an irregular contour or an infiltrative spread pattern are suspicious for sarcomatoid RCC or CDC.

The Director of Prostate Imaging: advancing care for prostate cancer patients

The radiologist's role extends far beyond interpretation and reporting of medical imaging. In this manuscript, we describe the role of the Director of Prostate Imaging. We believe that this model can and should be implemented at other institutions, ultimately serving to improve the care for prostate cancer patients. Moreover, this model can be translated to support the development of an array of patient-centered service lines not only in abdominal imaging, but throughout radiology practices at large.

Focal Laser Ablation of Prostate Cancer: Feasibility of Magnetic Resonance Imaging-Ultrasound Fusion for Guidance

PURPOSE

Focal laser ablation is a potential treatment in some men with prostate cancer. Currently focal laser ablation is performed by radiologists in a magnetic resonance imaging unit (in bore). We evaluated the safety and feasibility of performing focal laser ablation in a urology clinic (out of bore) using magnetic resonance imaging-ultrasound fusion for guidance.

MATERIALS AND METHODS

A total of 11 men with intermediate risk prostate cancer were enrolled in this prospective, institutional review board approved pilot study. Magnetic resonance imaging-ultrasound fusion was used to guide laser fibers transrectally into regions of interest harboring intermediate risk prostate cancer. Thermal probes were inserted for real-time monitoring of intraprostatic temperatures during laser activation. Multiparametric magnetic resonance imaging (3 Tesla) was done immediately after treatment and at 6 months along with comprehensive fusion biopsy.

RESULTS

Ten of 11 patients were successfully treated while under local anesthesia. Mean procedure time was 95 minutes (range 71 to 105). Posttreatment magnetic resonance imaging revealed a confined zone of nonperfusion in all 10 men. Mean zone volume was 4.3 cc (range 2.1 to 6.0). No CTCAE grade 3 or greater adverse events developed and no changes were observed in urinary or sexual function. At 6 months magnetic resonance imaging-ultrasound fusion biopsy of the treatment site showed no cancer in 3 patients, microfocal Gleason 3 + 3 in another 3 and persistent intermediate risk prostate cancer in 4.

CONCLUSIONS

Focal laser ablation of prostate cancer appears safe and feasible with the patient under local anesthesia in a urology clinic using magnetic resonance imaging-ultrasound fusion for guidance and thermal probes for monitoring. Further development is necessary to refine out of bore focal laser ablation and additional studies are needed to determine appropriate treatment margins and oncologic efficacy.

Evaluation of different mathematical models and different b-value ranges of diffusion-weighted imaging in peripheral zone prostate cancer detection using b-value up to 4500 s/mm2

OBJECTIVES

To evaluate the diagnostic performance of different mathematical models and different b-value ranges of diffusion-weighted imaging (DWI) in peripheral zone prostate cancer (PZ PCa) detection.

METHODS

Fifty-six patients with histologically proven PZ PCa who underwent DWI-magnetic resonance imaging (MRI) using 21 b-values (0-4500 s/mm2) were included. The mean signal intensities of the regions of interest (ROIs) placed in benign PZs and cancerous tissues on DWI images were fitted using mono-exponential, bi-exponential, stretched-exponential, and kurtosis models. The b-values were divided into four ranges: 0-1000, 0-2000, 0-3200, and 0-4500 s/mm2, grouped as A, B, C, and D, respectively. ADC, <D>, D*, f, DDC, α, Dapp, and Kapp were estimated for each group. The adjusted coefficient of determination (R2) was calculated to measure goodness-of-fit. Receiver operating characteristic curve analysis was performed to evaluate the diagnostic performance of the parameters.

RESULTS

All parameters except D* showed significant differences between cancerous tissues and benign PZs in each group. The area under the curve values (AUCs) of ADC were comparable in groups C and D (p = 0.980) and were significantly higher than those in groups A and B (p< 0.05 for all). The AUCs of ADC and Kapp in groups B and C were similar (p = 0.07 and p = 0.954), and were significantly higher than the other parameters (p< 0.001 for all). The AUCs of ADC in group D was slightly higher than Kapp (p = 0.002), and both were significantly higher than the other parameters (p< 0.001 for all).

CONCLUSIONS

ADC derived from conventional mono-exponential high b-value (3200 s/mm2) models is an optimal parameter for PZ PCa detection.

In-Bore 3-T MR-guided Transrectal Targeted Prostate Biopsy: Prostate Imaging Reporting and Data System Version 2-based Diagnostic Performance for Detection of Prostate Cancer

Purpose To determine the diagnostic yield of in-bore 3-T magnetic resonance (MR) imaging-guided prostate biopsy and stratify performance according to Prostate Imaging Reporting and Data System (PI-RADS) versions 1 and 2. Materials and Methods This study was HIPAA compliant and institution review board approved. In-bore 3-T MR-guided prostate biopsy was performed in 134 targets in 106 men who (a) had not previously undergone prostate biopsy, (b) had prior negative biopsy findings with increased prostate-specific antigen (PSA) level, or (c) had a prior history of prostate cancer with increasing PSA level. Clinical, diagnostic 3-T MR imaging was performed with in-bore guided prostate biopsy, and pathology data were collected. The diagnostic yields of MR-guided biopsy per patient and target were analyzed, and differences between biopsy targets with negative and positive findings were determined. Results of logistic regression and areas under the curve were compared between PI-RADS versions 1 and 2. Results Prostate cancer was detected in 63 of 106 patients (59.4%) and in 72 of 134 targets (53.7%) with 3-T MR imaging. Forty-nine of 72 targets (68.0%) had clinically significant cancer (Gleason score ≥ 7). One complication occurred (urosepsis, 0.9%). Patients who had positive target findings had lower apparent diffusion coefficient values (875 × 10^-6 mm²/sec vs 1111 × 10^-6 mm²/sec, respectively; P < .01), smaller prostate volume (47.2 cm³ vs 75.4 cm³, respectively; P < .01), higher PSA density (0.16 vs 0.10, respectively; P < .01), and higher proportion of PI-RADS version 2 category 3-5 scores when compared with patients with negative target findings. MR targets with PI-RADS version 2 category 2, 3, 4, and 5 scores had a positive diagnostic yield of three of 23 (13.0%), six of 31 (19.4%), 39 of 50 (78.0%), and 24 of 29 (82.8%) targets, respectively. No differences were detected in areas under the curve for PI-RADS version 2 versus 1. Conclusion In-bore 3-T MR-guided biopsy is safe and effective for prostate cancer diagnosis when stratified according to PI-RADS versions 1 and 2. ^©RSNA, 2016.

Restriction spectrum imaging improves MRI-based prostate cancer detection

PURPOSE

To compare the diagnostic performance of restriction spectrum imaging (RSI), with that of conventional multi-parametric (MP) magnetic resonance imaging (MRI) for prostate cancer (PCa) detection in a blinded reader-based format.

METHODS

Three readers independently evaluated 100 patients (67 with proven PCa) who underwent MP-MRI and RSI within 6 months of systematic biopsy (N = 67; 23 with targeting performed) or prostatectomy (N = 33). Imaging was performed at 3 Tesla using a phased-array coil. Readers used a five-point scale estimating the likelihood of PCa present in each prostate sextant. Evaluation was performed in two separate sessions, first using conventional MP-MRI alone then immediately with MP-MRI and RSI in the same session. Four weeks later, another scoring session used RSI and T2-weighted imaging (T2WI) without conventional diffusion-weighted or dynamic contrast-enhanced imaging. Reader interpretations were then compared to prostatectomy data or biopsy results. Receiver operating characteristic curves were performed, with area under the curve (AUC) used to compare across groups.

RESULTS

MP-MRI with RSI achieved higher AUCs compared to MP-MRI alone for identifying high-grade (Gleason score greater than or equal to 4 + 3=7) PCa (0.78 vs. 0.70 at the sextant level; P < 0.001 and 0.85 vs. 0.79 at the hemigland level; P = 0.04). RSI and T2WI alone achieved AUCs similar to MP-MRI for high-grade PCa (0.71 vs. 0.70 at the sextant level). With hemigland analysis, high-grade disease results were similar when comparing RSI + T2WI with MP-MRI, although with greater AUCs compared to the sextant analysis (0.80 vs. 0.79).

CONCLUSION

Including RSI with MP-MRI improves PCa detection compared to MP-MRI alone, and RSI with T2WI achieves similar PCa detection as MP-MRI.

Gadoxetic acid: pearls and pitfalls

Gadoxetic acid is a hepatocyte-specific magnetic resonance imaging contrast agent with the ability to detect and characterize focal liver lesions and provide structural and functional information about the hepatobiliary system. Knowledge of the pharmacokinetics of gadoxetic acid is paramount to understanding imaging protocol and lesion appearance and facilitates identification and avoidance of undesired effects with use of this intravenous contrast agent. This article reviews the utility of gadoxetic acid in liver and biliary imaging, with emphasis on the hepatobiliary phase.

Utilizing time-driven activity-based costing to understand the short- and long-term costs of treating localized, low-risk prostate cancer

BACKGROUND

Given the costs of delivering care for men with prostate cancer remain poorly described, this article reports the results of time-driven activity-based costing (TDABC) for competing treatments of low-risk prostate cancer.

METHODS

Process maps were developed for each phase of care from the initial urologic visit through 12 years of follow-up for robotic-assisted laparoscopic prostatectomy (RALP), cryotherapy, high-dose rate (HDR) and low-dose rate (LDR) brachytherapy, intensity-modulated radiation therapy (IMRT), stereotactic body radiation therapy (SBRT), and active surveillance (AS). The last modality incorporated both traditional transrectal ultrasound (TRUS) biopsy and multiparametric-MRI/TRUS fusion biopsy. The costs of materials, equipment, personnel, and space were calculated per unit of time and based on the relative proportion of capacity used. TDABC for each treatment was defined as the sum of its resources.

RESULTS

Substantial cost variation was observed at 5 years, with costs ranging from $7,298 for AS to $23,565 for IMRT, and they remained consistent through 12 years of follow-up. LDR brachytherapy ($8,978) was notably cheaper than HDR brachytherapy ($11,448), and SBRT ($11,665) was notably cheaper than IMRT, with the cost savings attributable to shorter procedure times and fewer visits required for treatment. Both equipment costs and an inpatient stay ($2,306) contributed to the high cost of RALP ($16,946). Cryotherapy ($11,215) was more costly than LDR brachytherapy, largely because of increased single-use equipment costs ($6,292 vs $1,921). AS reached cost equivalence with LDR brachytherapy after 7 years of follow-up.

CONCLUSIONS

The use of TDABC is feasible for analyzing cancer services and provides insights into cost-reduction tactics in an era focused on emphasizing value. By detailing all steps from diagnosis and treatment through 12 years of follow-up for low-risk prostate cancer, this study has demonstrated significant cost variation between competing treatments.

Prostate cancer detection with magnetic resonance-ultrasound fusion biopsy: The role of systematic and targeted biopsies

BACKGROUND

The current study was conducted to evaluate the performance of magnetic resonance (MR)-ultrasound-guided fusion biopsy in diagnosing clinically significant prostate cancer (csCaP).

METHODS

A total of 1042 men underwent multiparametric MR imaging (mpMRI) and fusion biopsy consecutively in a prospective trial (2009-2014). An expert reader graded mpMRI regions of interest (ROIs) as 1 to 5 using published protocols. The fusion biopsy device was used to obtain targeted cores from ROIs (when present) followed by a fusion image-guided, 12-core systematic biopsy in all men, even if no suspicious ROI was noted. The primary endpoint of the study was the detection of csCaP (ie, Gleason score ≥ 7).

RESULTS

Among 825 men with ≥ 1 suspicious ROI of ≥ grade 3, 289 (35%) were found to have csCaP. Powerful predictors of csCaP were ROI grade (grade 5 vs grade 3: odds ratio, 6.5 [P<.01]) and prostate-specific antigen density (each increase of 0.05 ng/mL/cc: odds ratio, 1.4 [P<.01]). Combining systematic and targeted biopsies resulted in the detection of more patients with csCaP (289 patients) than targeting (229 patients) or systematic (199 patients) biopsy alone. Among patients with no suspicious ROI, 35 (16%) were found to have csCaP on systematic biopsy.

CONCLUSIONS

In this prospective trial, MR-ultrasound fusion biopsy allowed for the detection of csCaP, with a direct relationship noted with ROI grade and prostate-specific antigen density. The combination of targeted and systematic biopsy detected more csCaP than either modality alone; systematic biopsies revealed csCaP in 16% of men with no suspicious MRI target. The advantages of this new biopsy method are apparent, but issues of cost, training, and reliability await resolution before its widespread adoption.

Focal Laser Ablation of Prostate Cancer: Phase I Clinical Trial

PURPOSE

Focal laser ablation is an investigational technique to treat prostate cancer in a region confined manner via coagulative necrosis. This phase I trial primarily examines the safety of transrectal magnetic resonance imaging guided (in-bore) focal laser ablation in men with intermediate risk prostate cancer. An exploratory end point is cancer control after 6 months.

MATERIALS AND METHODS

In an institutional review board approved trial we studied focal laser ablation in 8 men with intermediate risk prostate cancer diagnosed using magnetic resonance-ultrasound fusion. Focal laser ablation was performed by inserting a cylindrically diffusing, water cooled laser fiber into magnetic resonance visible regions of interest, followed by interstitial heating at 10 to 15 W for up to 3 minutes. Secondary safety monitors (thermal probes) were inserted to assess the accuracy of magnetic resonance thermometry. Comprehensive magnetic resonance-ultrasound fusion biopsy was performed after 6 months. Adverse events and health related quality of life questionnaires were recorded.

RESULTS

Focal laser ablation was successfully performed in all 8 subjects. No grade 3 or greater adverse events occurred and no changes in International Prostate Symptom Score or International Index of Erectile Function 5 were observed. Ablation zones, as measured by posttreatment magnetic resonance imaging, had a median volume of 3 cc or 7.7% of prostate volume. Prostate specific antigen decreased in 7 men (p <0.01). At followup magnetic resonance-ultrasound fusion biopsy cancer was not detected in the ablation zone in 5 men but was present outside the treatment margin in 6 men.

CONCLUSIONS

Focal laser ablation of the prostate is feasible and safe in men with intermediate risk prostate cancer without serious adverse events or changes in urinary or sexual function at 6 months. Comprehensive biopsy followup indicates that larger treatment margins than previously thought necessary may be required for complete tumor ablation.

Prostate diffusion imaging with distortion correction

PURPOSE

Diffusion imaging in the prostate is susceptible to distortion from B0 inhomogeneity. Distortion correction in prostate imaging is not routinely performed, resulting in diffusion images without accurate localization of tumors. We performed and evaluated distortion correction for diffusion imaging in the prostate.

MATERIALS AND METHODS

28 patients underwent pre-operative MRI (T2, Gadolinium perfusion, diffusion at b=800 s/mm(2)). The restriction spectrum protocol parameters included b-values of 0, 800, 1500, and 4000 s/mm(2) in 30 directions for each nonzero b-value. To correct for distortion, forward and reverse trajectories were collected at b=0 s/mm(2). Distortion maps were generated to reflect the offset of the collected data versus the corrected data. Whole-mount histology was available for correlation.

RESULTS

Across the 27 patients evaluated (excluding one patient due to data collection error), the average root mean square distortion distance of the prostate was 3.1 mm (standard deviation, 2.2mm; and maximum distortion, 12 mm).

CONCLUSION

Improved localization of prostate cancer by MRI will allow better surgical planning, targeted biopsies and image-guided treatment therapies. Distortion distances of up to 12 mm due to standard diffusion imaging may grossly misdirect treatment decisions. Distortion correction for diffusion imaging in the prostate improves tumor localization.

MRI-Derived Restriction Spectrum Imaging Cellularity Index is Associated with High Grade Prostate Cancer on Radical Prostatectomy Specimens

Purpose: We evaluate a novel magnetic resonance imaging (MRI) technique to improve detection of aggressive prostate cancer (PCa).

Materials and Methods: We performed a retrospective analysis of pre-surgical prostate MRI scans using an advanced diffusion-weighted imaging technique called restriction spectrum imaging (RSI), which can be presented as a normalized z-score statistic. Scans were acquired prior to radical prostatectomy. Prostatectomy specimens were processed using whole-mount sectioning and regions of interest (ROIs) were drawn around individual PCa tumors. Corresponding ROIs were drawn on the MRI imaging and paired with ROIs in regions with no pathology. RSI z-score and conventional apparent diffusion coefficient (ADC) values were recorded for each ROI. Paired t-test, ANOVA, and logistic regression analyses were performed.

Results: We evaluated 28 patients with 64 ROIs (28 benign and 36 PCa). The mean difference in RSI z-score (PCa ROI–Benign ROI) was 2.17 (SE = 0.11; p < 0.001) and in ADC was 551 mm²/s (SE = 80 mm²/s; paired t-test, p < 0.001). The differences in the means among all groups (benign, primary Gleason 3, and primary Gleason 4) was significant for both RSI z-score (F_3,64 = 97.7, p < 0.001) and ADC (F_3,64 = 13.9, p < 0.001). A t-test was performed on only PCa tumor ROIs (n = 36) to determine PCa aggressiveness (Gleason 3 vs. Gleason 4) revealing that RSI z-score was still significant (p = 0.03), whereas, ADC values were no longer significant (p = 0.08). In multivariable analysis adjusting for age and race, RSI z-score was associated with PCa aggressiveness (OR 10.3, 95% CI: 1.4–78.0, p = 0.02) while ADC trended to significance (p = 0.07).

Conclusion: The RSI-derived normalized cellularity index is associated with aggressive PCa as determined by pathologic Gleason scores. Further utilization of RSI techniques may serve to enhance standardized reporting systems for PCa in the future.

Correlation of gleason scores with magnetic resonance diffusion tensor imaging in peripheral zone prostate cancer

BACKGROUND

To investigate tumor aggressiveness in peripheral zone prostate cancer (PCa) by correlating Gleason score (GS) with diffusion tensor imaging (DTI) from multiparametric magnetic resonance imaging (MRI) at 3.0 Tesla (T).

METHODS

Eighty-three patients with pathological proven peripheral zone PCa whose GS in at least one core biopsy met the criteria(GS ≤3+3, GS 3+4, GS 4+3, or GS ≥4+4) were included in this study. DTI was performed using b values of 0 and 800 s/mm(2) with 32 directions in all patients on a 3.0T MRI scanner. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values were calculated from the DTI data of patients with the previously mentioned four categories of Gleason scores. An association between DTI measurements(FA, ADC) and GS was tested using the Spearman rank correlation analysis.

RESULTS

FA values in the sextants found to harbor cancer were positively correlated with the GS(r = 0.48; P < 0.001), while the ADC values were negatively correlated with GS(r = -0.54; P < 0.001). Statistical significance(P < 0.05) was found for FA values among different GS groups, with the exception of GS 3+4 versus GS 4+3 (P = 0.105). The differences between the ADC values were statistically significant for all four different scores(all P < 0.05).

CONCLUSION

Quantitative DTI at 3.0T MRI shows a significant association with GS in the evaluation of tumor aggressiveness in peripheral zone PCa, which may be useful to ensure concordance of biopsy results and therefore make the appropriate decision in the management of patients with PCa.

Multifocality and prostate cancer detection by multiparametric magnetic resonance imaging: correlation with whole-mount histopathology

BACKGROUND

Multiparametric magnetic resonance imaging (mp-MRI) is increasingly used in prostate cancer (CaP). Understanding the limitations of tumor detection, particularly in multifocal disease, is important in its clinical application.

OBJECTIVE

To determine predictors of CaP detection by mp-MRI as confirmed by whole-mount histopathology.

DESIGN, SETTING, AND PARTICIPANTS

A retrospective study was performed of 122 consecutive men who underwent mp-MRI before radical prostatectomy at a single referral academic center. A genitourinary radiologist and pathologist collectively determined concordance.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The odds of tumor detection were calculated for clinical, MRI, and histopathologic variables using a multivariate logistic regression model.

RESULTS AND LIMITATIONS

The 122 patients had 283 unique histologically confirmed CaP tumor foci. Gleason score was 6 in 21 (17%), 7 in 88 (72%), and ≥8 in 13 (11%) patients. Of the 122 cases, 44 (36%) had solitary and 78 (64%) had multifocal tumors. Overall mp-MRI sensitivity for tumor detection was 47% (132/283), with increased sensitivity for larger (102/141 [72%] >1.0 cm), higher-grade (96/134 [72%] Gleason ≥7) tumors, and index tumors (98/122 [80%]). Index tumor status, size, and prostate weight were significant predictors of detection in a multivariate analysis, and multifocality did not adversely impact detection of index tumors. A prostatectomy population was necessary by design, which may limit the ability to generalize these results.

CONCLUSIONS

Sensitivity for tumor detection increased with tumor size and grade. Index tumor status and tumor size were the strongest predictors of tumor detection, regardless of tumor focality. Some 80% of index tumors were detected, but nonindex tumor detection, even of high-grade lesions, was poor. These findings have important implications for focal therapy.

PATIENT SUMMARY

We evaluated the ability of magnetic resonance imaging (MRI) to detect cancer in patients undergoing prostatectomy. We found that tumor size and grade were important predictors of tumor detection, and although cancer is often multifocal, MRI is often able to detect the worst focus of cancer.

Fast 3D T2 -weighted imaging using variable flip angle transition into driven equilibrium (3D T2 -TIDE) balanced SSFP for prostate imaging at 3T

PURPOSE

Three-dimensional (3D) T2 -weighted fast spin echo (FSE) imaging of the prostate currently requires long acquisition times. Our objective was to develop a fast 3D T2 -weighted sequence for prostate imaging at 3T using a variable flip angle transition into driven equilibrium (T2 -TIDE) scheme.

METHODS

3D T2 -TIDE uses interleaved spiral-out phase encode ordering to efficiently sample the ky -kz phase encodes and also uses the transient balanced steady-state free precession signal to acquire the center of k-space for T2 -weighted imaging. Bloch simulations and images from 10 healthy subjects were acquired to evaluate the performance of 3D T2 -TIDE compared to 3D FSE.

RESULTS

3D T2 -TIDE images were acquired in 2:54 minutes compared to 7:02 minutes for 3D FSE with identical imaging parameters. The signal-to-noise ratio (SNR) efficiency was significantly higher for 3D T2 -TIDE compared to 3D FSE in nearly all tissues, including periprostatic fat (45 ± 12 vs. 31 ± 7, P < 0.01), gluteal fat (48 ± 8 vs. 41 ± 10, P = 0.12), right peripheral zone (20 ± 4 vs. 16 ± 8, P = 0.12), left peripheral zone (17 ± 2 vs. 12 ± 3, P < 0.01), and anterior fibromuscular stroma (12 ± 4 vs. 4 ± 2, P < 0.01).

CONCLUSION

3D T2 -TIDE images of the prostate can be acquired quickly with SNR efficiency that exceeds that of 3D FSE.

Magnetic resonance imaging-ultrasound fusion biopsy for prediction of final prostate pathology

PURPOSE

We explored the impact of magnetic resonance imaging-ultrasound fusion prostate biopsy on the prediction of final surgical pathology.

MATERIALS AND METHODS

A total of 54 consecutive men undergoing radical prostatectomy at UCLA after fusion biopsy were included in this prospective, institutional review board approved pilot study. Using magnetic resonance imaging-ultrasound fusion, tissue was obtained from a 12-point systematic grid (mapping biopsy) and from regions of interest detected by multiparametric magnetic resonance imaging (targeted biopsy). A single radiologist read all magnetic resonance imaging, and a single pathologist independently rereviewed all biopsy and whole mount pathology, blinded to prior interpretation and matched specimen. Gleason score concordance between biopsy and prostatectomy was the primary end point.

RESULTS

Mean patient age was 62 years and median prostate specific antigen was 6.2 ng/ml. Final Gleason score at prostatectomy was 6 (13%), 7 (70%) and 8-9 (17%). A tertiary pattern was detected in 17 (31%) men. Of 45 high suspicion (image grade 4-5) magnetic resonance imaging targets 32 (71%) contained prostate cancer. The per core cancer detection rate was 20% by systematic mapping biopsy and 42% by targeted biopsy. The highest Gleason pattern at prostatectomy was detected by systematic mapping biopsy in 54%, targeted biopsy in 54% and a combination in 81% of cases. Overall 17% of cases were upgraded from fusion biopsy to final pathology and 1 (2%) was downgraded. The combination of targeted biopsy and systematic mapping biopsy was needed to obtain the best predictive accuracy.

CONCLUSIONS

In this pilot study magnetic resonance imaging-ultrasound fusion biopsy allowed for the prediction of final prostate pathology with greater accuracy than that reported previously using conventional methods (81% vs 40% to 65%). If confirmed, these results will have important clinical implications.

Multiparametric MRI identifies and stratifies prostate cancer lesions: implications for targeting intraprostatic targets

PURPOSE

To assess the ability of multiparametric (mp) MRI (mp-MRI) to identify, stratify, and localize biopsy-proven prostate cancer lesions in a risk-stratified patient population.

METHODS AND MATERIALS

We retrospectively analyzed 57 patients who had mp-MRI and core needle biopsy during diagnostic prostate cancer evaluation. The MRI sequences were scored for suspicion of cancer with a previously described system. Distributions of mp-MRI scores were compared across National Comprehensive Cancer Network prostate cancer risk groups. The mp-MRI-identified lesions were compared with the location of positive core needle biopsies to assess mp-MRI localization of true lesions.

RESULTS

The mp-MRI scoring system identified lesions in 84% (48/57) of the patients, including 100% (12/12) in the high-risk group. Scores assigned to lesions in patients in intermediate- and high-risk groups were statistically higher than those in the low-risk group, with a relative risk of 6.72 (95% confidence interval: 2.32-19.51, p<0.001) of having an aggressive score assigned in high-risk patients compared with the low-risk patients. In comparing the localization data from core needle biopsy, 68% of the patients had an MRI-identified lesion in or within one adjacent sextant of the same prostate hemigland, including 85% of aggressive lesions.

CONCLUSIONS

Use of mp-MRI at the time of diagnosis can identify intraprostatic lesions and assign suspicion for high-risk disease. These data show that high-risk patients are more likely to have suspicious imaging-identified lesions that correlate to the location of biopsy-proven prostate cancer. At this time, the use of mp-MRI to define focal targets represents a complementary tool to patient evaluation for focal therapy strategies.

The role of magnetic resonance imaging in delineating clinically significant prostate cancer

OBJECTIVE

To determine whether multiparametric magnetic resonance imaging might improve the identification of patients with higher risk disease at diagnosis and thereby reduce the incidence of undergrading or understaging.

METHODS

We retrospectively reviewed the clinical records of 115 patients who underwent multiparametric magnetic resonance imaging before radical prostatectomy. We used Epstein's criteria of insignificant disease with and without a magnetic resonance imaging (MRI) parameter (apparent diffusion coefficient) to calculate sensitivity, specificity, as well as negative and positive predictive values [NPV and PPV] across varying definitions of clinically significant cancer based on Gleason grade and tumor volume (0.2 mL, 0.5 mL, and 1.3 mL) on whole-mount prostate specimens. Logistic regression analysis was performed to determine the incremental benefit of MRI in delineating significant cancer.

RESULTS

The majority had a prostate-specific antigen from 4.1-10.0 (67%), normal rectal examinations (90%), biopsy Gleason score ≤ 6 (68%), and ≤ 2 cores positive (55%). Of the 58 patients pathologically staged with Gleason 7 or pT3 disease at prostatectomy, Epstein's criteria alone missed 12 patients (sensitivity of 79% and NPV of 68%). Addition of apparent diffusion coefficient improved the sensitivity and NPV for predicting significant disease at prostatectomy to 93% and 84%, respectively. MRI improved detection of large Gleason 6 (≥ 1.3 mL, P = .006) or Gleason ≥ 7 lesions of any size (P <.001).

CONCLUSION

Integration of MRI with existing clinical staging criteria helps identify patients with significant cancer. Clinicians should consider utilizing MRI in the decision-making process.

Radical prostatectomy: value of prostate MRI in surgical planning

The introduction of serum prostate-specific antigen to the prostate cancer screening algorithm has led to an increase in prostate cancer diagnosis as well as a migration toward lower-stage cancer at the time of diagnosis. This stage migration has coincided with changes in treatment options; these include active surveillance, new therapies, and advances in surgical techniques. Use of robot-assisted radical prostatectomy (RARP) as a surgical technique has seen a significant increase over the past several years: the number of patients undergoing RARP has risen from 1% to 40% of all prostatectomies from 2001-2006 to as many as 80% in 2010. The robotic interface provides a 3D magnified view of the surgical field, intuitive instrument manipulation, motion scaling, tremor filtration, and excellent dexterity and range of motion. However, in some cases, the lack of tactile (haptic) feedback may limit the surgeon's decision making ability in assessing malignant involvement of the neurovascular bundles. Pre-operative planning relies on nomograms based on limited clinical and prostate biopsy information. The surgical decision to spare or resect the neurovascular bundles is based on clinical information which is not spatially or anatomically based. Advances in magnetic resonance imaging (MRI) may provide spatially localized information to fill this void and aid surgical planning, particularly for robotic surgeons. In this review, we discuss the potential role of pre-operative MRI in surgical planning for radical prostatectomy.

Targeted biopsy in the detection of prostate cancer using an office based magnetic resonance ultrasound fusion device

PURPOSE

Targeted biopsy of lesions identified on magnetic resonance imaging may enhance the detection of clinically relevant prostate cancers. We evaluated prostate cancer detection rates in 171 consecutive men using magnetic resonance ultrasound fusion prostate biopsy.

MATERIALS AND METHODS

Subjects underwent targeted biopsy for active surveillance (106) or persistently increased prostate specific antigen but negative prior conventional biopsy (65). Before biopsy, each man underwent multiparametric magnetic resonance imaging at 3.0 Tesla. Lesions on magnetic resonance imaging were outlined in 3 dimensions and assigned increasing cancer suspicion levels (image grade 1 to 5) by a uroradiologist. A biopsy tracking system was used to fuse the stored magnetic resonance imaging with real-time ultrasound, generating a 3-dimensional prostate model on the fly. Working from the 3-dimensional model, transrectal biopsy of target lesions and 12 systematic biopsies were performed with the patient under local anesthesia in the clinic.

RESULTS

A total of 171 subjects (median age 65 years) underwent targeted biopsy. At biopsy, median prostate specific antigen was 4.9 ng/ml and prostate volume was 48 cc. A targeted biopsy was 3 times more likely to identify cancer than a systematic biopsy (21% vs 7%). Prostate cancer was found in 53% of men, 38% of whom had Gleason grade 7 or greater cancer. Of the men with Gleason 7 or greater cancer 38% had disease detected only on targeted biopsies. Targeted biopsy findings correlated with level of suspicion on magnetic resonance imaging. Of 16 men 15 (94%) with an image grade 5 target (highest suspicion) had prostate cancer, including 7 with Gleason 7 or greater cancer.

CONCLUSIONS

Prostate lesions identified on magnetic resonance imaging can be accurately targeted using magnetic resonance ultrasound fusion biopsy by a urologist in clinic. Biopsy findings correlate with level of suspicion on magnetic resonance imaging.

Migration of intrauterine devices: radiologic findings and implications for patient care

Intrauterine devices (IUDs) are a commonly used form of contraception worldwide. However, migration of the IUD from its normal position in the uterine fundus is a frequently encountered complication, varying from uterine expulsion to displacement into the endometrial canal to uterine perforation. Different sites of IUD translocation vary in terms of their clinical significance and subsequent management, and the urgency of communicating IUD migration to the clinician is likewise variable. Expulsion or intrauterine displacement of the IUD leads to decreased contraceptive efficacy and should be clearly communicated, since it warrants IUD replacement to prevent unplanned pregnancy. Embedment of the IUD into the myometrium can usually be managed in the outpatient clinical setting but occasionally requires hysteroscopic removal. Complete uterine perforation, in which the IUD is partially or completely within the peritoneal cavity, requires surgical management, and timely and direct communication with the clinician is essential in such cases. Careful evaluation for intraabdominal complications is also important, since they may warrant urgent or emergent surgical intervention. The radiologist plays an important role in the diagnosis of IUD migration and should be familiar with its appearance at multiple imaging modalities.

Clear cell renal cell carcinoma: multiphasic multidetector CT imaging features help predict genetic karyotypes

PURPOSE

To determine whether imaging characteristics at multiphasic multidetector computed tomography (CT) correlate with common karyotypic abnormalities in patients with clear cell renal cell carcinomas (ccRCCs).

MATERIALS AND METHODS

Institutional review board approval was obtained, and informed consent was waived for this HIPAA-compliant retrospective study. From January 2000 through September 2007, the prenephrectomy multiphasic (corticomedullary, nephrographic, and excretory phases), multidetector helical CT images of 58 histologically proved and karyotyped ccRCCs were reviewed by two readers with experience in abdominal imaging. Imaging features assessed included degree of attenuation, contour, and presence of calcifications and neovascularity. These features were independently correlated with specific karyotypic abnormalities on the resected specimens. Degree of attenuation data were analyzed with logistic regression for significance (P < .05), and morphologic characteristics were analyzed with odds ratios for assessing their diagnostic power.

RESULTS

On unenhanced scans, 7% (two of 28) of ccRCCs with the loss of chromosome 3p were calcified, whereas 37% (11 of 30) of lesions without this anomaly were calcified (odds ratio, 0.13). During the corticomedullary phase, ccRCCs with the loss of chromosome Y enhanced more than those without this anomaly (130.0 vs 102.5 HU, P = .04), and ccRCCs with trisomy 7 enhanced less than those without this anomaly (105.8 vs 139.3 HU, P = .04). During the excretory phase, ccRCCs with trisomy 5 enhanced more than those without this anomaly (115.5 vs 83.4 HU, P = .03).

CONCLUSION

The genetic makeup of ccRCCs affects their imaging features at multidetector CT examinations. Multidetector CT imaging characteristics may help suggest differences at the cytogenetic level among ccRCCs.

Clinical application of a 3D ultrasound-guided prostate biopsy system

OBJECTIVES

Prostate biopsy (Bx) has for 3 decades been performed in a systematic, but blind fashion using 2D ultrasound (US). Herein is described the initial clinical evaluation of a 3D Bx tracking and targeting device (Artemis; Eigen, Grass Valley, CA). Our main objective was to test accuracy of the new 3D method in men undergoing first and follow-up Bx to rule out prostate cancer (CaP).

MATERIALS AND METHODS

Patients in the study were men ages 35-87 years (66.1 ± 9.9), scheduled for Bx to rule out CaP, who entered into an IRB-approved protocol. A total of 218 subjects underwent conventional trans-rectal US (TRUS); the tracking system was then attached to the US probe; the prostate was scanned and a 3D reconstruction was created. All Bx sites were visualized in 3D and tracked electronically. In 11 men, a pilot study was conducted to test ability of the device to return a Bx to an original site. In 47 men, multi-parametric 3 Tesla MRI, incorporating T2-weighted images, dynamic contrast enhancement, and diffusion-weighted imaging, was performed in advance of the TRUS, allowing the stored MRI images to be fused with real-time US during biopsy. Lesions on MRI were delineated by a radiologist, assigned a grade of CaP suspicion, and fused into TRUS for biopsy targeting.

RESULTS

3D Bx tracking was completed successfully in 180/218 patients, with a success rate approaching 95% among the last 50 men. Average time for Bx with the Artemis device was 15 minutes with an additional 5 minutes for MRI fusion and Bx targeting. In the tracking study, an ability to return to prior Bx sites (n=32) within 1.2 ± 1.1 mm SD was demonstrated and was independent of prostate volume or location of Bx site. In the MRI fusion study, when suspicious lesions were targeted, a 33% Bx-positivity rate was found compared with a 7% positivity rate for systematic, nontargeted Bx (19/57 cores vs. 9/124 cores, P=0.03).

CONCLUSION

Use of 3D tracking and image fusion has the potential to transform MRI into a clinical tool to aid biopsy and improve current methods for diagnosis and follow-up of CaP.

Water-selective spectral–spatial contrast-enhanced breast MRI for cancer detection in patients with extracapsular and injected free silicone

OBJECTIVE

This study investigates the use of contrast-enhanced, T1-weighted, water-selective spectral-spatial 3D gradient echo magnetic resonance imaging (MRI) with magnetization transfer (3DSSMT) for detecting breast cancer in patients with intraparenchymal silicone.

CONCLUSION

Water-selective 3DSSMT provides superior fat and silicone suppression in patients with free silicone as compared with conventional fat saturation. It enables direct, high-quality, high-spatial-resolution, T1-weighted breast MRI of contrast enhancement without the need for subtraction processing and aids diagnosis of cancer in the breast with free silicone.

Conventional imaging and 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography for predicting the clinical outcome of patients with previously treated Hodgkin's disease

PURPOSE

The aim of this study was to determine the ability of 2-deoxy-2-[(18)F]fluoro-d-glucose positron emission tomography (FDG-PET) to predict the clinical outcome of previously treated patients with Hodgkin's Disease (HD).

PATIENTS AND METHODS

Thirty-two patients were studied with PET within a median interval of 5.2 months after treatment. Conventional imaging (CI) performed within two months before PET included 2.9+/-1.2 imaging tests/patient. To determine the independent ability of FDG-PET to predict the clinical outcome, PET images were reread without knowledge of CI and clinical history. Study end points were disease-free survival, or clinical evidence of disease or death. PET and CI stages were also compared for each patient.

RESULTS

Using the clinical outcome as gold standard after a median follow-up of 14 months, 21 of 32 patients (65%) were considered disease-free while 11 of 32 patients (35%) had evidence for disease or had died. The predictive accuracy of PET was 91% vs. 66% for conventional imaging (P<0.05). The positive predictive value (PPV) was also significantly higher for PET (79% vs. 50%, P<0.05), while its negative predictive value (NPV) tended to be higher than that of CI (100% vs. 86%, P=0.08). Kaplan-Meier analysis for disease-free survival showed a significant difference between PET-negative and -positive results. No such difference was observed between CI-positive and -negative results (P=0.35).

CONCLUSION

Whole-body FDG-PET imaging modified the clinical stage in 28% of patients. Moreover, FDG-PET predicted patient outcome with a higher predictive accuracy than CI. This superior prognostic accuracy was achieved with a single FDG-PET study vs. 2.9+/-1.2 CI procedures/patient.

Conventional imaging and 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography for predicting the clinical outcome of previously treated non-hodgkin's lymphoma patients

PURPOSE

The aim of this study was to determine the impact of positron emission tomography (PET) with 2-deoxy-2-[18F]fluoro-D-glucose (FDG) and combined conventional imaging on clinical stage and their ability to predict the clinical outcome of previously treated lymphoma patients.

PROCEDURES

Seventy-eight patients with Non-Hodgkin's Lymphoma (NHL) were studied with PET within a median interval of 5.3 months after treatment. Conventional imaging performed after treatment and within three months before PET included 3.3+/-1.3 imaging tests/patient. To determine the independent ability of PET for predicting clinical outcome, PET images were re-read in a blinded fashion. Study endpoints were disease-free survival, or clinical evidence of disease or death.

RESULTS

PET downstaged 18 patients, upstaged nine and revealed the same stage as conventional imaging in 51 patients. Using the clinical outcome as gold standard, the positive and negative predictive values of PET were 95% and 83% versus 72% and 67% for conventional imaging (P<0.05). The prognostic accuracy of PET was superior to that of conventional imaging (90 vs. 71%; P<0.05). Kaplan-Meier analysis for disease-free survival showed a significant difference between PET negative and PET positive results (P<0.0001).

CONCLUSION

Whole-body FDG-PET imaging modified the clinical stage in 35% of lymphoma patients who were reevaluated after treatment. Moreover, FDG-PET predicted patient outcome with a higher predictive accuracy than conventional imaging. This superior prognostic accuracy was achieved with a single FDG-PET study versus multiple conventional imaging procedures/patient.