Interscanner comparison of dynamic contrast-enhanced MRI in prostate cancer: 1.5 versus 3 T MRI

Dynamic Contrast-Enhanced Study in the mpMRI of the Prostate-Unnecessary or Underutilised? A Narrative Review

The aim of this review is to summarise recent scientific literature regarding the clinical use of DCE-MRI as a component of multiparametric resonance imaging of the prostate. This review presents the principles of DCE-MRI acquisition and analysis, the current role of DCE-MRI in clinical practice with special regard to its role in presently available categorisation systems, and an overview of the advantages and disadvantages of DCE-MRI described in the current literature. DCE-MRI is an important functional sequence that requires intravenous administration of a gadolinium-based contrast agent and gives information regarding the vascularity and capillary permeability of the lesion. Although numerous studies have confirmed that DCE-MRI has great potential in the diagnosis and monitoring of prostate cancer, its role is still inadequate in the PI-RADS categorisation. Moreover, there have been numerous scientific discussions about abandoning the intravenous application of gadolinium-based contrast as a routine part of MRI examination of the prostate. In this review, we summarised the recent literature on the advantages and disadvantages of DCE-MRI, focusing on an overview of currently available data on bpMRI and mpMRI, as well as on studies providing information on the potential better usability of DCE-MRI in improving the sensitivity and specificity of mpMRI examinations of the prostate.

Diagnostic value of 3.0 T versus 1.5 T MRI in staging prostate cancer: systematic review and meta-analysis

Purpose

To compare the diagnostic performance of 3.0 T and 1.5 T MRI in the staging of prostate cancer.

Material and methods

English-language studies on the diagnostic accuracy of 3.0 T and 1.5 T MRI in prostate cancer staging published through May 2020 were searched for in relevant databases. The focus was on studies in which both 3.0 T and 1.5 T MRI were performed in the study population, to reduce interstudy heterogeneity. Pooled sensitivity, specificity, diagnostic odds ratio (DOR), and area under the receiver operating characteristic curve were determined for 3.0 T and for 1.5 T along with 95% confidence intervals (CIs).

Results

Out of 8 studies identified, 4 met the inclusion criteria. 3.0 T (n = 160) had a pooled sensitivity of 69.5% (95% CI: 56.4-80.1%) and a pooled specificity of 48.8% (95% CI: 6.0-93.4%), while 1.5 T (n = 139) had a pooled sensitivity of 70.6% (95% CI: 55.0-82.5%; p = 0.91) and a pooled specificity of 41.7% (95% CI: 6.2-88.6%; p = 0.88). The pooled DOR for 3.0 T was 3 (95% CI: 0-26.0%), while the pooled DOR for 1.5 T was 2 (95% CI: 0-18.0%), which was not a significant difference (p = 0.89).

Conclusions

3.0 T has slightly better diagnostic performance than 1.5 T MRI in prostate cancer staging (3 vs. 2), although without statistical significance. Our findings suggest the need for larger, randomized trials directly comparing 3.0 T and 1.5 T MRI in prostate cancer.

1.5 vs 3 Tesla Magnetic Resonance Imaging: A Review of Favorite Clinical Applications for Both Field Strengths-Part 1

ABSTRACT

Whole-body magnetic resonance imaging (MRI) systems with a field strength of 3 T have been offered by all leading manufacturers for approximately 2 decades and are increasingly used in clinical diagnostics despite higher costs. Technologically, MRI systems operating at 3 T have reached a high standard in recent years, as well as the 1.5-T devices that have been in use for a longer time. For modern MRI systems with 3 T, more complexity is required, especially for the magnet and the radiofrequency (RF) system (with multichannel transmission). Many clinical applications benefit greatly from the higher field strength due to the higher signal yield (eg, imaging of the brain or extremities), but there are also applications where the disadvantages of 3 T might outweigh the advantages (eg, lung imaging or examinations in the presence of implants). This review describes some technical features of modern 1.5-T and 3-T whole-body MRI systems, and reports on the experience of using both types of devices in different clinical settings, with all sections written by specialist radiologists in the respective fields.This first part of the review includes an overview of the general physicotechnical aspects of both field strengths and elaborates the special conditions of diffusion imaging. Many relevant aspects in the application areas of musculoskeletal imaging, abdominal imaging, and prostate diagnostics are discussed.

Arguments against using an abbreviated or biparametric prostate MRI protocol

Currently there is a lot of interest in the use of a "biparametric" or "abbreviated" prostate MR protocol, which usually refers to removal of the dynamic contrast-enhanced (DCE) MRI, in the detection of clinically significant prostate cancer. In this article we describe the benefits of DCE as part of the PI-RADS lexicon, with particular reference to its role in PI-RADS V2 category 3 peripheral zone lesions. We also discuss the benefits of triplanar T2-weighted images, and finally discuss how a mpMRI protocol is of benefit in prostate cancer staging, in evaluating for local disease recurrence, and as a biomarker for neoadjuvant therapy response.

Accuracy of multiparametric magnetic resonance imaging for diagnosing prostate Cancer: a systematic review and meta-analysis

BACKGROUND

The application of multiparametric magnetic resonance imaging (mpMRI) for diagnosis of prostate cancer has been recommended by the European Association of Urology (EAU), National Comprehensive Cancer Network (NCCN), and European Society of Urogenital Radiology (ESUR) guidelines. The purpose of this study is to systematically review the literature on assessing the accuracy of mpMRI in patients with suspicion of prostate cancer.

METHOD

We searched Embase, Pubmed and Cochrane online databases from January 12,000 to October 272,018 to extract articles exploring the possibilities that the pre-biopsy mpMRI can enhance the diagnosis accuracy of prostate cancer. The numbers of true- and false-negative results and true- and false-positive ones were extracted to calculate the corresponding sensitivity and specificity of mpMRI. Study quality was assessed using QUADAS-2 tool. Random effects meta-analysis and a hierarchical summary receiver operating characteristic (HSROC) plot were performed for further study.

RESULTS

After searching, we acquired 3741 articles for reference, of which 29 studies with 8503 participants were eligible for inclusion. MpMRI maintained impressive diagnostic value, the area under the HSROC curve was 0.87 (95%CI,0.84-0.90). The sensitivity and specificity for mpMRI were 0.87 [95%CI, 0.81-0.91] and 0.68 [95%CI,0.56-0.79] respectively. The positive likelihood ratio was 2.73 [95%CI 1.90-3.90]; negative likelihood ratio was 0.19 [95% CI 0.14,-0.27]. The risk of publication bias was negligible with P = 0.96.

CONCLUSION

Results of the meta-analysis suggest that mpMRI is a sensitive tool to diagnose prostate cancer. However, because of the high heterogeneity existing among the included studies, further studies are needed to apply the results of this meta-analysis in clinic.

A meta-analysis of use of Prostate Imaging Reporting and Data System Version 2 (PI-RADS V2) with multiparametric MR imaging for the detection of prostate cancer

OBJECTIVES

This meta-analysis was undertaken to review the diagnostic accuracy of PI-RADS V2 for prostate cancer (PCa) detection with multiparametric MR (mp-MR).

METHODS

A comprehensive literature search of electronic databases was performed by two observers independently. Inclusion criteria were original research using the PI-RADS V2 system in reporting prostate MRI. The methodological quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. Data necessary to complete 2 × 2 contingency tables were obtained from the included studies.

RESULTS

Thirteen studies (2,049 patients) were analysed. This is an initial meta-analysis of PI-RADs V2 and the overall diagnostic accuracy in diagnosing PCa was as follows: pooled sensitivity, 0.85 (0.78-0.91); pooled specificity, 0.71 (0.60-0.80); pooled positive likelihood ratio (LR+), 2.92 (2.09-4.09); pooled negative likelihood ratio (LR-), 0.21 (0.14-0.31); pooled diagnostic odds ratio (DOR), 14.08 (7.93-25.01), respectively. Positive predictive values ranged from 0.54 to 0.97 and negative predictive values ranged from 0.26 to 0.92.

CONCLUSION

Currently available evidence indicates that PI-RADS V2 appears to have good diagnostic accuracy in patients with PCa lesions with high sensitivity and moderate specificity. However, no recommendation regarding the best threshold can be provided because of heterogeneity.

KEY POINTS

• PI-RADS V2 shows good diagnostic accuracy for PCa detection. • Initially pooled specificity of PI-RADS v2 remains moderate. • PCa detection is increased by experienced radiologists. • There is currently a high heterogeneity in prostate diagnostics with MRI.

[Quantitative perfusion imaging in magnetic resonance imaging]

CLINICAL/METHODICAL ISSUE

Magnetic resonance imaging (MRI) is recognized for its superior tissue contrast while being non-invasive and free of ionizing radiation. Due to the development of new scanner hardware and fast imaging techniques during the last decades, access to tissue and organ functions became possible. One of these functional imaging techniques is perfusion imaging with which tissue perfusion and capillary permeability can be determined from dynamic imaging data.

STANDARD RADIOLOGICAL METHODS

Perfusion imaging by MRI can be performed by two approaches, arterial spin labeling (ASL) and dynamic contrast-enhanced (DCE) MRI. While the first method uses magnetically labelled water protons in arterial blood as an endogenous tracer, the latter involves the injection of a contrast agent, usually gadolinium (Gd), as a tracer for calculating hemodynamic parameters.

PERFORMANCE

Studies have demonstrated the potential of perfusion MRI for diagnostics and also for therapy monitoring.

ACHIEVEMENTS

The utilization and application of perfusion MRI are still restricted to specialized centers, such as university hospitals. A broad application of the technique has not yet been implemented.

PRACTICAL RECOMMENDATIONS

The MRI perfusion technique is a valuable tool that might come broadly available after implementation of standards on European and international levels. Such efforts are being promoted by the respective professional bodies.

DCE MRI of prostate cancer

DCE MRI is an established component of multi-parametric MRI of the prostate. The sequence highlights the vascularization of cancerous lesions, allowing readers to corroborate suspicious findings on T2W and DW MRI and to note subtle lesions not visible on the other sequences. In this article, we review the technical aspects, methods of evaluation, limitations, and future perspectives of DCE MRI.

Improving bladder cancer imaging using 3-T functional dynamic contrast-enhanced magnetic resonance imaging

OBJECTIVES

The objective of this study was to assess the capability of T2-weighted magnetic resonance imaging (T2W-MRI) and the additional diagnostic value of dynamic contrast-enhanced MRI (DCE-MRI) using multitransmit 3 T in the localization of bladder cancer.

MATERIALS AND METHODS

This prospective study was approved by the local institutional review board. Thirty-six patients were included in the study and provided informed consent. Magnetic resonance imaging scans were performed with T2W-MRI and DCE-MRI on a 3-T multitransmit system. Two observers (with 12 and 25 years of experience) independently interpreted T2W-MRI before DCE-MRI data (maps of pharmacokinetic parameters) to localize bladder tumors. The pathological examination of cystectomy bladder specimens was used as a reference criteria standard. The McNemar test was performed to evaluate the differences in sensitivity, specificity, and accuracy. Scores of κ were calculated to assess interobserver agreement.

RESULTS

The sensitivity, specificity, and accuracy of the localization with T2W-MRI alone were 81% (29/36), 63% (5/8), and 77% (34/44) for observer 1 and 72% (26/36), 63% (5/8), and 70% (31/44) for observer 2. With additional DCE-MRI available, these values were 92% (33/36), 75% (6/8), and 89% (39/44) for observer 1 and 92% (33/36), 63% (5/8), and 86% (38/44) for observer 2. Dynamic contrast-enhanced MRI significantly (P<0.01) improved the sensitivity and accuracy for observer 2. For the 23 patients treated with chemotherapy, DCE-MRI also significantly (P<0.02) improved the sensitivity and accuracy of bladder cancer localization with T2W-MRI alone for observer 2. Scores of κ were 0.63 for T2W-MRI alone and 0.78 for additional DCE-MRI. Of 7 subcentimeter malignant tumors, 4 (57%) were identified on T2W images and 6 (86%) were identified on DCE maps. Of 11 malignant tumors within the bladder wall thickening, 6 (55%) were found on T2W images and 10 (91%) were found on DCE maps.

CONCLUSIONS

Compared with conventional T2W-MRI alone, the addition of DCE-MRI improved interobserver agreement as well as the localization of small malignant tumors and those within bladder wall thickening.

The clinical value of dynamic contrast-enhanced magnetic resonance imaging at 3.0T to detect prostate cancer

Objective

To compare dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) and T2-weighted imaging (T2WI) at 3.0T for detection of prostate cancer.

Methods

Patients with elevated prostate-specific antigen underwent T2WI and DCE-MRI prior to prostate needle biopsy. The sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) of T2WI and DCE-MRI to diagnose prostate cancer were evaluated. The relationship between Gleason score and prostate cancer detection by DCE-MRI was evaluated.

Results

Prostate adenocarcinoma was histopathologically confirmed in 44/75 patients. DCE-MRI had significantly higher sensitivity, accuracy and NPV than T2WI. The detection rate of prostate cancer by DCE-MRI was significantly better for tumours with Gleason score 7–9 than for those Gleason score 4–6.

Conclusion

DCE-MRI at 3.0T can significantly improve prostate cancer detection using simple visual diagnostic criteria, compared with T2WI.

The clinical utility of fMRI for identifying covert awareness in the vegetative state: a comparison of sensitivity between 3T and 1.5T

In the last few years, mental imagery fMRI paradigms have been used successfully to identify covert command-following and awareness in some patients who are thought to be entirely vegetative. However, to date there is only evidence supporting their use at magnetic fields of 3T, which limits their applicability in clinical settings where lower field strengths are typically used. Here, we test the 'gold standard' fMRI paradigm for detecting residual awareness in non-responsive patients by comparing its sensitivity at 1.5T and 3T in the same group of healthy volunteers. We were able to successfully detect brain activity showing command-following in most participants at both 3T and 1.5T, with similar reliability. These results demonstrate that fMRI assessment of covert awareness is clinically viable and therefore justify a broader use of these methods in standard assessments in severely brain injured patients.

Functional imaging of acute kidney injury at 3 Tesla: investigating multiple parameters using DCE-MRI and a two-compartment filtration model

OBJECT

To investigate how MR-based parameters reflect functional changes in kidneys with acute kidney injury (AKI) using dynamic contrast enhanced MRI and a two-compartment renal filtration model.

MATERIALS AND METHODS

MRI data of eight male Lewis rats were analyzed retrospectively. Five animals were subjected to AKI, three native rats served as control. All animals underwent perfusion imaging by dynamic contrast-enhanced MRI. Renal blood volume, glomerular filtration rate (GFR) as well as plasma and tubular mean transit times were estimated from regions-of-interest drawn in the renal cortex. Differences between healthy kidneys and kidneys subjected to AKI were analyzed using a paired t-test.

RESULTS

Significant differences between ischemic and healthy kidneys could only be detected for the glomerular filtration rate. For all other calculated parameters, differences were present, however not significant. In rats with AKI, average single kidney GFR was 0.66 ± 0.37 ml/min for contralateral and 0.26 ± 0.12 ml/ min for diseased kidneys (P = 0.0254). For the healthy control group, the average GFR was 0.39 ± 0.06 ml/min and 0.41 ± 0.11 ml/min, respectively. Differences between diseased kidneys of AKI rats and ipsilateral kidneys of the healthy control group were significant (P = 0.0381).

CONCLUSION

Significant differences of functional parameters reflecting damage of the renal tissue of kidneys with AKI compared to the contralateral, healthy kidneys could only be detected by GFR. GFR might be a useful parameter that allows for a spatially resolved detection of abnormal changes of renal tissue by AKI.

Evaluation of the PI-RADS scoring system for classifying mpMRI findings in men with suspicion of prostate cancer

Purpose. To evaluate the ESUR scoring system (PI-RADS) for multiparametric MRI of the prostate in clinical routine and to define a reliable way to generate an overall PI-RADS score. Methods. Retrospective analysis of all patients with a history of negative prebiopsies, who underwent 3 Tesla multiparametric MRI from October 2011 to April 2013 (n = 143): PI-RADS scores for each single modality were defined. To generate the overall PI-RADS score, an algorithm based approach summing up each single-modality score to a sum-score was compared to a more subjective approach, weighting the single modalities dependent on the radiologist's impression. Because of ongoing cancer suspicion 73 patients underwent targeted mpMRI-ultrasound image fusion rebiopsy. For this group thresholds for tumor incidences and malignancy were calculated. Results. 39 (53%) out of 73 targeted rebiopsies were cancer positive. The PI-RADS score correlated well with tumor incidence (AUC of 0.86, 95% CI 0.78 to 0.94) and malignancy (AUC 0.84, 95% CI 0.68 to 0.99). Regarding the sum-score a threshold of ≥10 turned out to be reliable for cancer detection (sensitivity 90%, specificity 62%) and for ≥13 for indicating higher malignancy (Gleason ≥4 + 3) (sensitivity 80%, specificity 86%). To generate the overall PI-RADS score, the use of an algorithm based approach was more reliable than that of the approach based on the radiologist's impression. Conclusion. The presented scoring system correlates well with tumor incidence and malignancy. To generate the overall PI-RADS score, it seems to be advisable to use an algorithm based instead of a subjective approach.