Summary Emerging evidence has linked MRI signal changes in deep nuclei of the brain with repeated administration of gadolinium-based contrast agents. Gadolinium deposits have been confirmed in brain ...tissue, most notably in the dentate nuclei and globus pallidus. Although some linear contrast agents appear to cause greater MRI signal changes than some macrocyclic agents, deposition of gadolinium has also been observed with macrocyclic agents. However, the extent of gadolinium deposition varies between agents. Furthermore, the clinical significance of the retained gadolinium in the brain, if any, remains unknown. No data are available in human beings or animals to show adverse clinical effects due to the gadolinium deposition in the brain. On behalf of the International Society for Magnetic Resonance in Medicine, we present recommendations for the clinical and research use of gadolinium-based contrast agents. These recommendations might evolve as new evidence becomes available.
Abstract The use of breast magnetic resonance imaging (MRI) is rapidly increasing. EUSOMA organised a workshop in Milan on 20–21st October 2008 to evaluate the evidence currently available on ...clinical value and indications for breast MRI. Twenty-three experts from the disciplines involved in breast disease management – including epidemiologists, geneticists, oncologists, radiologists, radiation oncologists, and surgeons – discussed the evidence for the use of this technology in plenary and focused sessions. This paper presents the consensus reached by this working group. General recommendations, technical requirements, methodology, and interpretation were firstly considered. For the following ten indications, an overview of the evidence, a list of recommendations, and a number of research issues were defined: staging before treatment planning; screening of high-risk women; evaluation of response to neoadjuvant chemotherapy; patients with breast augmentation or reconstruction; occult primary breast cancer; breast cancer recurrence; nipple discharge; characterisation of equivocal findings at conventional imaging; inflammatory breast cancer; and male breast. The working group strongly suggests that all breast cancer specialists cooperate for an optimal clinical use of this emerging technology and for future research, focusing on patient outcome as primary end-point.
Performing quality control to detect image artifacts and data-processing errors is crucial in structural magnetic resonance imaging, especially in developmental studies. Currently, many studies rely ...on visual inspection by trained raters for quality control. The subjectivity of these manual procedures lessens comparability between studies, and with growing study sizes quality control is increasingly time consuming. In addition, both inter-rater as well as intra-rater variability of manual quality control is high and may lead to inclusion of poor quality scans and exclusion of scans of usable quality. In the current study we present the Qoala-T tool, which is an easy and free to use supervised-learning model to reduce rater bias and misclassification in manual quality control procedures using FreeSurfer-processed scans. First, we manually rated quality of N = 784 FreeSurfer-processed T1-weighted scans acquired in three different waves in a longitudinal study. Different supervised-learning models were then compared to predict manual quality ratings using FreeSurfer segmented output data. Results show that the Qoala-T tool using random forests is able to predict scan quality with both high sensitivity and specificity (mean area under the curve (AUC) = 0.98). In addition, the Qoala-T tool was also able to adequately predict the quality of two novel unseen datasets (total N = 872). Finally, analyses of age effects showed that younger participants were more likely to have lower scan quality, underlining that scan quality might confound findings attributed to age effects. These outcomes indicate that this procedure could further help to reduce variability related to manual quality control, thereby benefiting the comparability of data quality between studies.
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•Variability of manual quality control procedures reduces comparability among studies.•We introduce Qoala-T to automatically assess quality of FreeSurfer-processed scans.•Scan quality of novel datasets was adequately predicted using the Qoala-T tool.•In three different datasets younger age was associated with lower scan quality.•Qoala-T is publicly available and easy-to-use as an add-on to manual QC.
Resting‐state functional magnetic resonance imaging (rsfMRI) has been developed as a method of investigating spontaneous neural activity. Based on its low‐frequency signal synchronization, rsfMRI has ...made it possible to identify multiple macroscopic structures termed resting‐state networks (RSNs) on a single scan of less than 10 minutes. It is easy to implement even in clinical practice, in which assigning tasks to patients can be challenging. These advantages have accelerated the adoption and growth of rsfMRI. Recently, studies on the global rsfMRI signal have attracted increasing attention. Because it primarily arises from physiological events, less attention has hitherto been paid to the global signal than to the local network (i.e., RSN) component. However, the global signal is not a mere nuisance or a subsidiary component. On the contrary, it is quantitatively the dominant component that accounts for most of the variance in the rsfMRI signal throughout the brain and provides rich information on local hemodynamics that can serve as an individual‐level diagnostic biomarker. Moreover, spatiotemporal analyses of the global signal have revealed that it is closely and fundamentally associated with the organization of RSNs, thus challenging the basic assumptions made in conventional rsfMRI analyses and views on RSNs. This review introduces new concepts emerging from rsfMRI spatiotemporal analyses focusing on the global signal and discusses how they may contribute to future clinical medicine.
Evidence Level
5
Technical Efficacy
Stage 1
Purpose:
Transcranial magnetic resonance‐guided focused ultrasound (TcMRgFUS) brain treatment systems compensate for skull‐induced beam aberrations by adjusting the phase and amplitude of individual ...ultrasound transducer elements. These corrections are currently calculated based on a preacquired computed tomography (CT) scan of the patient's head. The purpose of the work presented here is to demonstrate the feasibility of using ultrashort echo‐time magnetic resonance imaging (UTE MRI) instead of CT to calculate and apply aberration corrections on a clinical TcMRgFUS system.
Methods:
Phantom experiments were performed in three ex‐vivo human skulls filled with tissue‐mimicking hydrogel. Each skull phantom was imaged with both CT and UTE MRI. The MR images were then segmented into “skull” and “not‐skull” pixels using a computationally efficient, threshold‐based algorithm, and the resulting 3D binary skull map was converted into a series of 2D virtual CT images. Each skull was mounted in the head transducer of a clinical TcMRgFUS system (ExAblate Neuro, Insightec, Israel), and transcranial sonications were performed using a power setting of approximately 750 acoustic watts at several different target locations within the electronic steering range of the transducer. Each target location was sonicated three times: once using aberration corrections calculated from the actual CT scan, once using corrections calculated from the MRI‐derived virtual CT scan, and once without applying any aberration correction. MR thermometry was performed in conjunction with each 10‐s sonication, and the highest single‐pixel temperature rise and surrounding‐pixel mean were recorded for each sonication.
Results:
The measured temperature rises were ∼45% larger for aberration‐corrected sonications than for noncorrected sonications. This improvement was highly significant (p < 10−4). The difference between the single‐pixel peak temperature rise and the surrounding‐pixel mean, which reflects the sharpness of the thermal focus, was also significantly larger for aberration‐corrected sonications. There was no significant difference between the sonication results achieved using CT‐based and MR‐based aberration correction.
Conclusions:
The authors have demonstrated that transcranial focal heating can be significantly improved in vitro by using UTE MRI to compute skull‐induced ultrasound aberration corrections. Their results suggest that UTE MRI could be used instead of CT to implement such corrections on current 0.7 MHz clinical TcMRgFUS devices. The MR image acquisition and segmentation procedure demonstrated here would add less than 15 min to a clinical MRgFUS treatment session.
There is growing interest to implement multiparametric magnetic resonance imaging (mpMRI) and MR-guided biopsy (MRGB) for biopsy-naïve men with suspected prostate cancer.
Primary objective was to ...compare and evaluate an MRI pathway and a transrectal ultrasound-guided biopsy (TRUSGB) pathway in biopsy-naïve men with prostate-specific antigen levels of ≥3ng/ml.
A prospective, multicenter, powered, comparative effectiveness study included 626 biopsy-naïve patients (from February 2015 to February 2018).
All patients underwent prebiopsy mpMRI followed by systematic TRUSGB. Men with suspicious lesions on mpMRI also underwent MRGB prior to TRUSGB. MRGB was performed using the in-bore approach.
Clinically significant prostate cancer (csPCa) was defined as grade group ≥2 (Gleason score ≥3+4) in any core. The main secondary objectives were the number of men who could avoid biopsy after nonsuspicious mpMRI, the number of biopsy cores taken, and oncologic follow-up. Differences in proportions were tested using McNemar's test with adjusted Wald confidence intervals for differences of proportions with matched pairs.
The MRI pathway detected csPCa in 159/626 (25%) patients and insignificant prostate cancer (insignPCa) in 88/626 patients (14%). TRUSGB detected csPCa in 146/626 patients (23%) and insignPCa in 155/626 patients (25%). Relative sensitivity of the MRI pathway versus the TRUSGB pathway was 1.09 for csPCa (p=0.17) and 0.57 for insignPCa (p<0.0001). The total number of biopsy cores reduced from 7512 to 849 (–89%). The MRI pathway enabled biopsy avoidance in 309/626 (49%) patients due to nonsuspicious mpMRI. Immediate TRUSGB detected csPCa in only 3% (10/309) of these patients, increasing to 4% (13/309) with 1-yr follow-up. At the same time, TRUSGB would overdetect insignPCa in 20% (63/309). “Focal saturation” by four additional perilesional cores to MRGB improved the detection of csPCa in 21/317 (7%) patients. Compared with the literature, our proportion of nonsuspicious mpMRI cases is significantly higher (27–36% vs 49%) and that of equivocal cases is lower (15–28% vs 6%). This is probably due to the high-quality standard in this study. Therefore, a limitation is the duplication of these results in less experienced centers.
In biopsy-naïve men, the MRI pathway compared with the TRUSGB pathway results in an identical detection rate of csPCa, with significantly fewer insignPCa cases. In this high-quality standard study, almost half of men have nonsuspicious MRI, which is higher compared with other studies. Not performing TRUS biopsy is at the cost of missing csPCa only in 4%.
We compared magnetic resonance imaging (MRI) with MRI-guided biopsy against standard transrectal ultrasound biopsy for the diagnosis of prostate cancer in biopsy-naïve men. Our results show that patients can benefit from MRI because biopsy may be omitted in half of men, and fewer indolent cancers are detected, without compromising the detection of harmful disease. Men also need fewer needles to make a diagnosis.
In biopsy-naïve patients, a magnetic resonance imaging (MRI) pathway compared with a transrectal ultrasound-guided biopsy pathway significantly reduces the detection rate of insignificant prostate cancer without impairing the detection rate of clinically significant prostate cancer. There is a potential to reduce the number of men requiring biopsy after nonsuspicious MRI to half, with an acceptable underdetection rate of 4%.
Management of bladder cancer (BC) is primarily driven by stage, grade, and biological potential. Knowledge of each is derived using clinical, histopathological, and radiological investigations. This ...multimodal approach reduces the risk of error from one particular test, but may present a staging dilemma when results conflict. Multiparametric magnetic resonance imaging (mpMRI) may improve patient care through imaging of the bladder with better resolution of the tissue planes than computed tomography and without radiation exposure.
To define a standardized approach to imaging and reporting mpMRI for BC, by developing a VI-RADS score.
We created VI-RADS (Vesical Imaging-Reporting And Data System) through consensus using existing literature.
We describe standard imaging protocols and reporting criteria (including size, location, multiplicity, and morphology) for bladder mpMRI. We propose a five-point VI-RADS score, derived using T2-weighted MRI, diffusion-weighted imaging, and dynamic contrast enhancement, which suggests the risks of muscle invasion. We include sample images used to understand VI-RADS.
We hope that VI-RADS will standardize reporting, facilitate comparisons between patients, and in future years, will be tested and refined if necessary. While we do not advocate mpMRI for all patients with BC, this imaging may compliment pathology or reduce radiation-based imaging. Bladder mpMRI may be most useful in patients with non–muscle-invasive cancers, in expediting radical treatment or for determining response to bladder-sparing approaches.
Magnetic resonance imaging (MRI) scans for bladder cancer are becoming more common and may provide accurate information that helps improve patient care. Here, we describe a standardized reporting criterion for bladder MRI. This should improve communication between doctors and allow better comparisons between patients.
Magnetic resonance imaging (MRI) scans for bladder cancer are becoming more common and may provide accurate information that helps improve patient care. Here, we describe a standardized reporting criterion for bladder MRI. This should improve communication between doctors and allow better comparisons between patients.
Sustained pain is a major characteristic of clinical pain disorders, but it is difficult to assess in isolation from co-occurring cognitive and emotional features in patients. In this study, we ...developed a functional magnetic resonance imaging signature based on whole-brain functional connectivity that tracks experimentally induced tonic pain intensity and tested its sensitivity, specificity and generalizability to clinical pain across six studies (total n = 334). The signature displayed high sensitivity and specificity to tonic pain across three independent studies of orofacial tonic pain and aversive taste. It also predicted clinical pain severity and classified patients versus controls in two independent studies of clinical low back pain. Tonic and clinical pain showed similar network-level representations, particularly in somatomotor, frontoparietal and dorsal attention networks. These patterns were distinct from representations of experimental phasic pain. This study identified a brain biomarker for sustained pain with high potential for clinical translation.
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