This study compared the image quality and diagnostic utility of stack-of-stars echo-unbalanced T1 relaxation-enhanced steady-state (SOS echo-uT1RESS) with the widely used magnetization-prepared rapid gradient-echo (MPRAGE) sequence in brain tumor imaging. In this prospective, two-center observational study, each participant underwent 3T contrast-enhanced MRI of the brain with both standard MPRAGE and prototype SOS echo-uT1RESS sequences. Lesion size, contrast-to-noise ratio (CNR), and tumor-to-brain contrast were quantitatively analyzed. Overall image quality, lesion conspicuity, and image artifacts were scored on a 4-point Likert scale, while diagnostic performance and assessment of the vascular and dural involvement were compared side-by-side by three readers. Thirty-four adult patients (mean age, 64 years ± 13 [SD], 12 men) with known brain tumors (N = 6 intra-axial primary tumors; N = 14 intra-axial metastases; N = 14 extra-axial tumors) were enrolled in this study. There was no significant difference in CNR between MPRAGE and SOS echo-uT1RESS (29.4 ± 21.4 vs. 28.2 ± 16.5, respectively; p = 0.80, r = 0.03). SOS echo-uT1RESS demonstrated a 1.8-fold improvement in tumor-to-brain contrast compared with MPRAGE (0.7 ± 0.4 vs. 0.4 ± 0.3, respectively; p < 0.001, r = 0.81). While overall image quality and image artifacts were similar for both sequences, SOS echo-uT1RESS showed improved lesion conspicuity (p < 0.001, r = 0.51) and improved diagnostic performance (p < 0.001, r = 0.53), particularly for small metastases. SOS echo-uT1RESS enhanced lesion visibility, achieving approximately a 1.8-fold improvement in tumor-to-brain contrast compared to MPRAGE, although this finding may reflect both sequence properties and timing-related effects. The sequence maintained comparable overall image quality and robustness, making it a promising tool for brain tumor imaging.

BackgroundLuminal and hemodynamic evaluations of the cervical arteries inform the diagnosis and management of patients with cervical arterial disease.PurposeTo demonstrate a 3D nonenhanced quantitative quiescent interval slice‐selective (qQISS) magnetic resonance angiographic (MRA) strategy that provides simultaneous hemodynamic and luminal evaluation of the cervical arteries.Study TypeProspective.SubjectsSix healthy volunteers (3 female, 3 male, age = 35.7 ± 10.3 years) and 14 patients with cerebrovascular disease (12 female, 2 male, age = 56.6 ± 14.0 years).Field Strength/Sequences3 T, ungated 3D tilted‐slab qQISS, pulse‐gated 2D phase contrast (PC), ungated 3D PC, and 3D time‐of‐flight (TOF) gradient‐echo protocols.AssessmentFour readers scored 29 arterial segments on 3D qQISS volumes for image quality using a 4‐point scale (1: non‐diagnostic, 2: fair, 3: good, 4: excellent). Time‐averaged arterial flow velocities and volume flow rates obtained with qQISS and PC protocols were compared. Arterial lumen area and radius measures obtained with 3D protocols were compared in a subgroup.Statistical TestsGwet's AC2; intraclass correlation coefficient (ICC); Pearson's correlation; Bland–Altman. P values <0.05 were considered statistically significant.Results3D qQISS provided good‐to‐excellent image quality for depicting the cervical arteries (mean scores of 3.72 ± 0.55, 3.55 ± 0.66, 3.42 ± 0.72, and 3.66 ± 0.73 for readers 1, 2, 3, and 4) with significant inter‐reader agreement (AC2 = 0.91, ICC = 0.53) in image scoring, significantly agreed with pulse‐gated 2D PC for time‐averaged total flow velocity (ICC = 0.83) and volume flow rate (ICC = 0.92), and significantly agreed with 3D PC for total flow velocity (ICC = 0.70), volume flow rate (ICC = 0.91), and component flow velocity (ICC = 0.89). Compared with 3D PC, 3D qQISS better agreed with 3D TOF for arterial lumen area (ICC = 0.97 vs. 0.72) and radius (ICC = 0.94 vs. 0.74).Data ConclusionNonenhanced 3D qQISS provides high‐quality sub‐1 mm3 spatial resolution imaging of the cervical arteries, excellent agreement of arterial structural measures with respect to 3D TOF, and time‐averaged hemodynamic data without the need for additional PC imaging.Plain Language SummaryMagnetic resonance angiography (MRA), a method for depicting blood vessels within the body, can be used to evaluate arterial diseases and disorders of the neck. MRA methods routinely used to evaluate the neck arteries do not measure blood flow speed and volume, while other methods for obtaining this information provide less accurate pictures of arterial structure and are not routinely collected. This article reports a new method for MRA that clearly and efficiently portrays the neck arteries without using injected dyes, and provides measurements of arterial blood flow speed and volume.Evidence Level2Technical EfficacyStage 1

PURPOSE:This study aimed to evaluate the image quality and lesion characterization with Dixon unbalanced T1 relaxation-enahnced steady-state (uT1RESS) in comparison to magnetization-prepared rapid acquisition gradient echo (MPRAGE) pulse sequence for detecting brain tumors, focusing on its potential to improve diagnostic accuracy and enhance brain tumor assessment. METHODS:This single-center prospective study enrolled 20 patients (12 males, aged 35-83), with primary brain tumors and brain metastases. Both MPRAGE and Dixon uT1RESS were acquired at 3 T. Objective image quality was assessed by contrast-to-noise ratio (CNR), tumor-to-brain contrast, and tumor volume. Subjective image quality was assessed by two independent readers focusing on lesion visibility, lesion margins, motion, and static artifacts. A side-by-side comparison assessed diagnostic performance regarding lesion detection, evaluation of internal structure and vascular or dural invasion. RESULTS:Dixon uT1RESS had a reduced acquisition time (2 min 51 s vs. 4 min 52 s for MPRAGE) and showed significantly higher CNR and tumor-to-brain contrast compared to MPRAGE (p < 0.001). Subjectively, both sequences showed similar overall image quality. Dixon uT1RESS achieved more conspicuous lesions with better-defined lesion margins (p < 0.001), while MPRAGE performed better in evaluating internal lesion structure (p < 0.05). Dixon uT1RESS was rated better for lesion detection, with three lesions additionally identified on this sequence. Wilcoxon signed-rank test was used to assess differences. CONCLUSIONS:Dixon uT1RESS significantly improved tumor conspicuity and detection, particularly for small metastatic lesions. This new technique offers promising potential for enhancing clinical brain tumor imaging, though additional sequences may be necessary for comprehensive lesion characterization.

OBJECTIVES:Magnetization-prepared rapid gradient-echo (MP-RAGE) sequences are routinely acquired for brain exams, providing high conspicuity for enhancing lesions. Vessels, however, also appear bright, which can complicate the detection of small lesions. T1RESS (T1 relaxation-enhanced steady-state) sequences have been proposed as an alternative to MP-RAGE, offering improved lesion conspicuity and suppression of blood vessels. This work aims to evaluate the performance of radial T1RESS variants for motion-robust contrast-enhanced brain MRI. MATERIALS AND METHODS:Radial stack-of-stars sampling was implemented for steady-state free-precession-based rapid T1RESS acquisition with saturation recovery preparation. Three variants were developed using a balanced steady-state free-precession readout (bT1RESS), an unbalanced fast imaging steady precession (FISP) readout (uT1RESS-FISP), and an unbalanced reversed FISP readout (uT1RESS-PSIF). Image contrast was evaluated in numerical simulations and phantom experiments. The motion robustness of radial T1RESS was demonstrated with a motion phantom. Four patients and six healthy volunteers were scanned at 3 T and 0.55 T. Extensions were developed combining T1RESS with GRASP for dynamic imaging, with GRAPPA for accelerated scans, and with Dixon for fat/water separation. RESULTS:In simulations and phantom scans, uT1RESS-FISP provided higher signal intensity for regions with lower T1 values (<500 ms) compared with MP-RAGE. In motion experiments, radial uT1RESS-FISP showed fewer artifacts than MP-RAGE and Cartesian uT1RESS-FISP. In patients, both unbalanced uT1RESS variants provided higher lesion conspicuity than MP-RAGE. Blood vessels appeared bright with MP-RAGE, gray with uT1RESS-FISP, and dark with uT1RESS-PSIF. At 0.55 T, bT1RESS provided high signal-to-noise ratio T1-weighted images without banding artifacts. Lastly, dynamic T1RESS images with a temporal resolution of 10.14 seconds/frame were generated using the GRASP algorithm. CONCLUSIONS:Radial T1RESS sequences offer improved lesion conspicuity and motion robustness and enable dynamic imaging for contrast-enhanced brain MRI. Both uT1RESS variants showed higher tumor-to-brain contrast than MP-RAGE and may find application as alternative techniques for imaging uncooperative patients with small brain lesions.

BACKGROUND:A fundamental limitation of both computed tomography angiography (CTA) and contrast-enhanced MRA (CEMRA) is that angiographic image quality greatly deteriorates when scans are obtained after the first pass, so that the useful post-contrast scan window is limited to a few tens of seconds. To overcome this limitation, we recently described a breath-hold, slab-selective technique called equilibrium phase balanced T1 relaxation-enhanced steady-state (bT1RESS) that permits diagnostic CEMRA to be obtained for tens of minutes after contrast agent infusion. Further improving upon this technique, we implemented a highly efficient free-breathing version for very rapid whole-chest imaging and tested it in a series of patients. MAIN BODY:This study was IRB approved. 34 patients with cardiovascular indications were imaged using a standard CMR protocol plus a post-contrast prototype navigator-gated, whole-chest bT1RESS sequence using either 2×2 or 3×2 (slice x phase) generalized autocalibrating partially parallel acquisition (GRAPPA) acceleration. RESULTS:Median scan time for 20 patients using 3×2 acceleration was 1.25 min vs. 2.21 min for 14 patients using 2×2 acceleration. Mean blood pool-to-muscle signal intensity ratio for bT1RESS obtained >20 min post-contrast was 88% of the value for scans obtained <5 min post-contrast. Inline reconstruction time for a complete 128-slice data set was <15 s. Good-to-excellent image quality and visualization of the aorta, pulmonary arteries and veins, coronary origins, coronary sinus, left atrial appendage, atria and ventricles were obtained in all cases with 3×2 acceleration and all but one case with 2×2 acceleration. There was also excellent correlation (0.92/0.93, p<0.001) between left/right end-diastolic ventricular volumes obtained from short axis cine stacks vs. bT1RESS, and good-to-excellent correlation (0.84/0.64), p<0.001) for left/right end-diastolic atrial volumes. DISCUSSION AND CONCLUSION:Free-breathing, whole-chest bT1RESS shows promise as a highly efficient and useful method for cardiovascular imaging. Diagnostic quality scans can be acquired regardless of post-contrast scan delay. Given the very short scan and reconstruction times, navigator-gated bT1RESS can be easily incorporated into any CMR protocol to allow volumetric evaluation of the thoracic vasculature and heart. With further development, the technique could also prove useful for rapid 3D functional evaluation of the heart.

Atrial disease or myopathy is a growing concept in cardiovascular medicine, particularly in the context of atrial fibrillation, as well as amyloidosis and heart failure. Among cardiac imaging modalities, cardiovascular magnetic resonance (CMR) is particularly well suited for a comprehensive assessment of atrial myopathy, including tissue characterization and hemodynamics. The goal of this review article is to describe clinical applications and make recommendations on pulse sequences as well as imaging parameters to assess the left atrium and left atrial appendage. Furthermore, we aimed to create an overview of current and promising future emerging applications of left atrium-specific CMR pulse sequences focusing on both electrophysiologic (EP) and non-EP applications.

Magnetization-prepared rapid gradient-echo (MP-RAGE) sequences are routinely acquired for brain exams, providing high conspicuity for enhancing lesions. Vessels, however, also appear bright, which can complicate the detection of small lesions. T1RESS (T1 relaxation-enhanced steady-state) sequences have been proposed as an alternative to MP-RAGE, offering improved lesion conspicuity and suppression of blood vessels. This work aims to evaluate the performance of radial T1RESS variants for motion-robust contrast-enhanced brain MRI. Radial stack-of-stars sampling was implemented for steady-state free-precession–based rapid T1RESS acquisition with saturation recovery preparation. Three variants were developed using a balanced steady-state free-precession readout (bT1RESS), an unbalanced fast imaging steady precession (FISP) readout (uT1RESS-FISP), and an unbalanced reversed FISP readout (uT1RESS-PSIF). Image contrast was evaluated in numerical simulations and phantom experiments. The motion robustness of radial T1RESS was demonstrated with a motion phantom. Four patients and six healthy volunteers were scanned at 3 T and 0.55 T. Extensions were developed combining T1RESS with GRASP for dynamic imaging, with GRAPPA for accelerated scans, and with Dixon for fat/water separation. In simulations and phantom scans, uT1RESS-FISP provided higher signal intensity for regions with lower T1 values (<500 ms) compared with MP-RAGE. In motion experiments, radial uT1RESS-FISP showed fewer artifacts than MP-RAGE and Cartesian uT1RESS-FISP. In patients, both unbalanced uT1RESS variants provided higher lesion conspicuity than MP-RAGE. Blood vessels appeared bright with MP-RAGE, gray with uT1RESS-FISP, and dark with uT1RESS-PSIF. At 0.55 T, bT1RESS provided high signal-to-noise ratio T1-weighted images without banding artifacts. Lastly, dynamic T1RESS images with a temporal resolution of 10.14 seconds/frame were generated using the GRASP algorithm. Radial T1RESS sequences offer improved lesion conspicuity and motion robustness and enable dynamic imaging for contrast-enhanced brain MRI. Both uT1RESS variants showed higher tumor-to-brain contrast than MP-RAGE and may find application as alternative techniques for imaging uncooperative patients with small brain lesions.

Background: Three-dimensional (3D) contrast-enhanced magnetic resonance angiography (CEMRA) is routinely used for vascular evaluation. With existing techniques for CEMRA, diagnostic image quality is only obtained during the first pass of the contrast agent or shortly thereafter, whereas angiographic quality tends to be poor when imaging is delayed to the equilibrium phase. We hypothesized that prolonged blood pool contrast enhancement could be obtained by imaging with a balanced T1 relaxation-enhanced steady-state (bT1RESS) pulse sequence, which combines 3D balanced steady-state free precession (bSSFP) with a saturation recovery magnetization preparation to impart T1 weighting and suppress background tissues. An electrocardiographic-gated, two-dimensional-accelerated version with isotropic 1.1-mm spatial resolution was evaluated for breath-hold equilibrium phase CEMRA of the thoracic aorta and heart. Methods: The study was approved by the institutional review board. Twenty-one subjects were imaged using unenhanced 3D bSSFP, time-resolved CEMRA, first-pass gated CEMRA, followed by early and late equilibrium phase gated CEMRA and bT1RESS. Nine additional subjects were imaged using equilibrium phase 3D bSSFP and bT1RESS. Images were evaluated for image quality, aortic root sharpness, and visualization of the coronary artery origins, as well as using standard quantitative measures. Results: Equilibrium phase bT1RESS provided better image quality, aortic root sharpness, and coronary artery origin visualization than gated CEMRA (P < 0.05), and improved image quality and aortic root sharpness versus unenhanced 3D bSSFP (P < 0.05). It provided significantly larger apparent signal-to-noise and apparent contrast-to-noise ratio values than gated CEMRA and unenhanced 3D bSSFP (P < 0.05) and provided ninefold better fluid suppression than equilibrium phase 3D bSSFP. Aortic diameter and main pulmonary artery diameter measurements obtained with bT1RESS and first-pass gated CEMRA strongly correlated (P < 0.05). Conclusions: We found that using bT1RESS greatly prolongs the useful duration of blood pool contrast enhancement while improving angiographic image quality compared with standard CEMRA techniques. Although further study is needed, potential advantages for vascular imaging include eliminating the current requirement for first-pass imaging along with better reliability and accuracy for a wide range of cardiovascular applications.

ABSTRACT Background The aim of this work was to create and evaluate a preoperative non-contrast-enhanced (CE) magnetic resonance imaging (MRI)/angiography (MRA) protocol to assess renal function and visualize renal arteries and any abnormalities in potential living kidney donors. Methods In total, 28 subjects were examined using scintigraphy to determine renal function. In addition, 3D-pseudocontinuous arterial spin labeling (pCASL), a 2D-non-CE electrocardiogram-triggered radial quiescent interval slice-selective (QISS-MRA), and 4D-CE time-resolved angiography with interleaved stochastic trajectories (CE-MRA) were performed to assess renal perfusion, visualize renal arteries and detect any abnormalities. Two glomerular filtration rates [described by Gates (GFRG) and according to the Chronic Kidney Disease Epidemiology Collaboration formula (GFRCKD-EPI)]. The renal volumes were determined using both MRA techniques. Results The mean value of regional renal blood flow (rRBF) on the right side was significantly higher than that on the left. The agreements between QISS-MRA and CE-MRA concerning the assessment of absence or presence of an aberrant artery and renal arterial stenosis were perfect. The mean renal volumes measured in the right kidney with QISS-MRA were lower than the corresponding values of CE-MRA. In contrast, the mean renal volumes measured in the left kidney with both MRA techniques were similar. The correlation between the GFRG and rRBF was compared in the same manner as that between GFRCKD-EPI and rRBF. Conclusion The combination of pCASL and QISS-MRA constitute a reliable preoperative protocol with a total measurement time of <10 min without the potential side effects of gadolinium-based contrast agents or radiation exposure.

BACKGROUND:Standard Cartesian time-of-flight (TOF) head magnetic resonance angiography (MRA) is routinely used to evaluate the intracranial arteries, but does not provide quantitative hemodynamic information that is useful for patient risk stratification as well as for monitoring treatment and tracking changes in blood flow over time. Quantitative TOF (qTOF) MRA represents a new and efficient method for simultaneous evaluating the intracranial arteries and quantifying blood flow velocity, but it has not yet been evaluated in patients with cerebrovascular disease. PURPOSE:To evaluate qTOF for simultaneously evaluating the intracranial arteries and quantifying intracranial blood flow velocity in patients with cerebrovascular disease, without the need for a phase contrast (PC) scan. STUDY TYPE:Prospective. SUBJECTS:Twenty-four patients (18 female, 6 male) with cerebrovascular disease. FIELD STRENGTH/SEQUENCES:Head MRA at 3 T using gradient-echo 3D qTOF, standard Cartesian TOF, and PC protocols. ASSESSMENT:Three independent readers assessed arterial image quality using a 4-point scale (1: non-diagnostic, 4: excellent) and artifact presence. Total and component flow velocities obtained with qTOF and PC were measured. STATISTICAL TESTS:Wilcoxon signed-rank tests, Gwet's AC2, intraclass correlation coefficients (ICC) for absolute agreement, Bland-Altman analyses, tests of equal proportions. P values <0.05 were considered statistically significant. RESULTS:Averaged across readers and compared to standard Cartesian TOF, qTOF significantly improved overall arterial image quality (3.8 ± 0.2 vs. 3.6 ± 0.5), image quality at locations of pathology (3.7 ± 0.5 vs. 3.4 ± 0.7), and increased the proportion of evaluations rated without artifacts (63.9% [46/72] vs. 37.5% [27/72]). qTOF significantly agreed with PC for total flow velocity (ICC = 0.71) and component flow velocity (ICC = 0.89). DATA CONCLUSION:qTOF angiography of the head matched or improved upon the image quality of standard Cartesian TOF, reduced image artifacts, and provided quantitative hemodynamic data, without the need for a PC scan. EVIDENCE LEVEL:2 TECHNICAL EFFICACY: Stage 2.

We recently described the feasibility of using a prototype 3D unbalanced steady-state free precession (3D uSSFP) pulse sequence for dark blood imaging. We sought to determine whether this technique could be adapted for dark blood, susceptibility-insensitive imaging of the lungs. A breath-hold, ECG-gated version of 3D uSSFP was implemented for a pilot study of healthy volunteers and patients. Initial results suggest that 3D uSSFP allows efficient volumetric imaging of the lungs and can demonstrate even small lung nodules without artifacts. With further development, the technique could provide a radiation-free alternative to low-dose CT for lung cancer screening.

OBJECTIVES:Contrast-enhanced magnetic resonance imaging (MRI) is the cornerstone for brain tumor diagnosis and treatment planning. We have developed a novel dual-echo volumetric dark blood pulse sequence called Dixon unbalanced T1 relaxation-enhanced steady-state (uT 1 RESS) that improves the visibility of contrast-enhancing lesions while suppressing the tissue signals from blood vessels and fat. The purpose of this study was to test the hypothesis that Dixon uT 1 RESS would significantly improve the conspicuity of brain tumors compared with magnetization-prepared rapid gradient echo (MPRAGE), as well as to determine potential limitations of the technique. MATERIALS AND METHODS:This retrospective study was approved by the hospital institutional review board. Forty-seven adult patients undergoing an MRI scan for a brain tumor indication were included. Contrast-enhanced MRI of the brain was performed at 3 T using both MPRAGE and Dixon uT 1 RESS. To control for any impact of contrast agent washout during the scan procedure, Dixon uT 1 RESS was acquired in approximately half the subjects immediately after MPRAGE, and in the other half immediately before MPRAGE. Image quality, artifacts, and lesion detection were scored by 3 readers, whereas lesion apparent signal-to-noise ratio and lesion-to-background Weber contrast were calculated from region-of-interest measurements. RESULTS:Image quality was not rated significantly different between MPRAGE and Dixon uT 1 RESS, whereas motion artifacts were slightly worse with Dixon uT 1 RESS. Comparing Dixon uT 1 RESS with MPRAGE, the respective values for mean lesion apparent signal-to-noise ratio were not significantly different (199.31 ± 99.05 vs 203.81 ± 110.23). Compared with MPRAGE, Dixon uT 1 RESS significantly increased the tumor-to-brain contrast (1.60 ± 1.18 vs 0.61 ± 0.47 when Dixon uT1RESS was acquired before MPRAGE and 1.94 ± 0.97 vs 0.82 ± 0.55 when Dixon uT 1 RESS was acquired after MPRAGE). In patients with metastatic disease, Dixon uT 1 RESS detected at least 1 enhancing brain lesion that was missed by MPRAGE on average in 24.7% of patients, whereas Dixon uT 1 RESS did not miss any lesions that were demonstrated by MPRAGE. Dixon uT 1 RESS better detected vascular and dural invasion in a small number of patients. CONCLUSIONS:In conclusion, brain tumors were significantly more conspicuous at 3 T using Dixon uT 1 RESS compared with MPRAGE, with an approximately 2.5-fold improvement in lesion-to-background contrast irrespective of sequence order. It outperformed MPRAGE for the detection of brain metastases, dural or vascular involvement. These results suggest that Dixon uT 1 RESS could prove to be a useful adjunct or alternative to existing neuroimaging techniques for the postcontrast evaluation of intracranial tumors.

BACKGROUND:The widely used magnetization-prepared rapid gradient-echo (MPRAGE) sequence makes enhancing lesions and blood vessels appear bright after gadolinium administration. However, dark blood imaging using T1-weighted Sampling Perfection with Application optimized Contrast using different flip angle Evolution (T1 SPACE) can be advantageous since it improves the conspicuity of small metastases and leptomeningeal disease. As a potential alternative to T1 SPACE, we evaluated a new dark blood sequence called echo-uT1RESS (unbalanced T1 Relaxation-Enhanced Steady-State). PURPOSE:We compared the performance of echo-uT1RESS with Dixon fid-uT1RESS, MPRAGE, and T1 SPACE. STUDY TYPE:Retrospective, IRB approved. SUBJECTS/PHANTOM:Phantom to assess flow properties of echo-uT1RESS. Twenty-one patients (14 female, age range 35-82 years) with primary and secondary brain tumors. FIELD STRENGTH/SEQUENCES:3 Tesla/MPRAGE, T1 SPACE, Dixon fid-uT1RESS, echo-uT1RESS. ASSESSMENT:Flow phantom signal vs. velocity as a function of flip angle and sequence. Qualitative image assessment on 4-point scale. Quantitative evaluation of tumor-to-brain contrast, apparent contrast-to-noise ratio (aCNR), and vessel-to-brain aCNR. STATISTICAL TESTS:Friedman and Mann-Whitney U tests. A P value <0.05 was considered statistically significant. RESULTS:In the phantom, echo-uT1RESS showed greater flow-dependent signal loss than fid-uT1RESS. In patients, blood vessels appeared bright with MPRAGE, gray with fid-uT1RESS, and dark with T1 SPACE and echo-uT1RESS. For MPRAGE, Dixon fid-uT1RESS, echo-uT1RESS, and T1 SPACE, respective tumor-to-brain contrast values were 0.6 ± 0.3, 1.3 ± 0.5, 1.0 ± 0.4, and 0.6 ± 0.4, while normalized aCNR values were 68.9 ± 50.9, 128.4 ± 59.2, 74.2 ± 42.1, and 99.4 ± 73.9. DATA CONCLUSION:Volumetric dark blood contrast-enhanced brain MRI is feasible using echo-uT1RESS. The dark blood effect was improved vs. fid-uT1RESS, while both uT1RESS versions provided better tumor-to-brain contrast than MPRAGE. Whereas T1 SPACE provided better tumor aSNR, echo-uT1RESS provided better Weber contrast, lesion sharpness and a more consistent dark blood effect. EVIDENCE LEVEL:3 TECHNICAL EFFICACY: Stage 1.

(1) Background: Preoperative imaging of the lower leg arteries is essential for planning fibular grafting. The aim of this study was to evaluate the feasibility and clinical value of non-contrast-enhanced (CE) Quiescent-Interval Slice-Selective (QISS)-magnetic resonance angiography (MRA) for reliably visualizing the anatomy and patency of the lower leg arteries and for preoperatively determining the presence, number, and location of fibular perforators. (2) Methods: The anatomy and stenoses of the lower leg arteries and the presence, number, and location of fibular perforators were determined in fifty patients with oral and maxillofacial tumors. Postoperative outcomes of patients after fibula grafting were correlated with preoperative imaging, demographic, and clinical parameters. (3) Results: A regular three-vessel supply was present in 87% of the 100 legs. QISS-MRA was able to accurately assign the branching pattern in patients with aberrant anatomy. Fibular perforators were found in 87% of legs. More than 94% of the lower leg arteries had no relevant stenoses. Fibular grafting was performed in 50% of patients with a 92% success rate. (4) Conclusions: QISS-MRA has the potential to be used as a preoperative non-CE MRA technique for the diagnosis and detection of anatomic variants of lower leg arteries and their pathologies, as well as for the assessment of fibular perforators.

HomeRadiologyVol. 303, No. 3 PreviousNext Reviews and CommentaryFree AccessEditorialUnleashing the Immune System: Cardiac MRI Depicts Myocarditis from Immune Checkpoint InhibitorsRobert R. Edelman , Amit PursnaniRobert R. Edelman , Amit PursnaniAuthor AffiliationsFrom the Departments of Radiology (R.R.E.) and Medicine (A.P.), NorthShore University HealthSystem, 2650 Ridge Ave, Walgreen Bldg, G534, Evanston, IL 60201; Feinberg School of Medicine, Northwestern University, Chicago, Ill (R.R.E.); and Pritzker School of Medicine, University of Chicago, Chicago, Ill (A.P.).Address correspondence to R.R.E. (e-mail: [email protected]).Robert R. Edelman Amit PursnaniPublished Online:Mar 1 2022https://doi.org/10.1148/radiol.213294MoreSectionsPDF ToolsImage ViewerAdd to favoritesCiteTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinked In See also the article by Cadour et al in this issue.Dr Edelman is radiology chair at NorthShore University HealthSystem and professor of radiology at the Feinberg School of Medicine, Northwestern University. He is a recipient of the Gold Medals of the ISMRM and SCMR for scientific achievement. His clinical focus is cardiovascular MRI and CT, while his current research focuses on a novel MRI technique called T1 Relaxation-Enhanced Steady-State (T1RESS), which greatly improves the visibility of tumors at contrast-enhanced MRI.Download as PowerPointOpen in Image Viewer Dr Pursnani is director of advanced cardiac imaging at NorthShore University HealthSystem in Evanston, Ill, where he serves as Cardiology Fellowship Program director. He is a clinical associate professor of medicine at the University of Chicago. He initiated the cardio-oncology program at NorthShore and is a founding member of the Chicago Cardio-Oncology Consortium. His research interests include advanced imaging techniques in predicting outcomes in cardiomyopathy and structural heart disease.Download as PowerPointOpen in Image Viewer Immunotherapies have revolutionized the treatment of cancer over the past decade (1). There are currently dozens of immunotherapies already approved, with hundreds more in the developmental and regulatory pipelines. For many types of tumors, immunotherapies have already become the standard of care. Types of immunotherapies include anticancer vaccines and viruses; engineered T cells, such as chimeric antigen receptor T-cell therapies; monoclonal antibodies (these bind to specific targets on tumor cells to improve visibility to the immune system or enhance T-cell ability to kill the tumor); immunomodulators that enhance the body’s immune response against cancer; and immune checkpoint inhibitors (ICIs). These ICIs are the focus of the study by Cadour et al (2) in this issue of Radiology.The 2018 Nobel Prize in Physiology or Medicine was awarded to Tasuku Honjo and James Allison for their discovery of immune checkpoints, which are normal components of the immune system that exist to prevent an excessive immune response that might otherwise damage healthy tissues (3). However, when a tumor checkpoint protein, such as programmed death ligand 1, binds to a T-cell checkpoint protein, such as programmed death 1, the T cell is inactivated and prevented from killing the tumor cell. ICIs are antibodies that interfere with this binding, thus reactivating the tumoricidal capability of the T cell.The first ICI to be introduced into clinical use was ipilimumab (Yervoy; Bristol Myers Squibb), an antibody targeting cytotoxic T-lymphocyte antigen 4. The unprecedented success of ipilimumab reenergized the field of immunotherapy after this therapeutic agent was approved by the U.S. Food and Drug Administration in 2011 to treat advanced melanoma. Since then, ICIs have been used to treat breast, bladder, cervical, and many other solid tumor types (https://www.cancer.gov/about-cancer/treatment/types/immunotherapy/checkpoint-inhibitors), including cancers previously considered untreatable. However, in unleashing the immune system, these agents often cause widespread inflammation that can affect and damage many organs, including the heart muscle.Cardiac MRI is the single most comprehensive imaging modality for evaluating disorders of the heart and great vessels. For the heart, it allows concurrent evaluation of ventricular function, morphologic characteristics, perfusion, viability, blood flow, and tissue characterization (4,5). In routine clinical practice, it is used to evaluate a broad range of disorders, including cardiac masses, congenital heart disease, valve abnormalities, and cardiomyopathies. In the field of cardio-oncology, cardiac MRI has proven to be an essential adjunct to echocardiography for pretreatment risk stratification, the monitoring of potential toxic adverse effects of cancer therapies, and posttreatment surveillance for delayed cardiotoxic effects (6). Early detection of chemotherapy cardiotoxicity is essential to initiate prompt treatment, which improves the likelihood of substantial recovery of cardiac function. Since cardiac MRI is the most accurate and precise method for assessing cardiac function, serial scans can be used to detect the deterioration of left ventricular function in patients undergoing chemotherapy.Myocarditis is associated with several types of immunologically active agents, including tyrosine kinase inhibitors, proteasome inhibitors, and most especially, ICIs. While ICI-related myocarditis has a reported incidence on the order of 2% or less, outcomes are worse than for myocarditis in the general population, with the condition proving lethal in up to half of patients (7). In the study by Cadour et al (2), major adverse cardiac events (MACE) at 1 year had occurred in 21 of 33 patients with ICI-related myocarditis (64%). Myocarditis can manifest in several different ways, including myocardial infarction–like symptoms, heart failure, and arrhythmias, making it challenging to diagnose based only on the clinical presentation. Cardiac MRI is the best imaging modality to evaluate suspected myocarditis, especially with the widespread availability of myocardial mapping techniques and the introduction of the revised Lake Louise criteria. These criteria rely on the combination of a T1 criterion indicative of nonischemic myocardial injury (based on the presence of late gadolinium enhancement [LGE], abnormally increased native T1, or extracellular volume) and a T2 criterion indicative of myocardial edema (based on the presence of hyperintensity in T2-weighted short-tau inversion recovery or abnormally increased native T2) (8). Cardiac MRI can be used to guide patient management, including the cessation of ICI therapy, use of high-dose steroids, and the decision of whether invasive endomyocardial biopsy (EMB) is needed for further evaluation.In their retrospective study, Cadour and colleagues (2) used cardiac MRI to study 33 patients treated with ICIs with a definite or presumed diagnosis of ICI-related myocarditis. Two control groups were provided, consisting of patients with cancer without myocarditis scheduled to receive ICI therapy and patients with viral myocarditis. Only 61% of patients (20 of 33) with ICI-related myocarditis fulfilled the updated Lake Louise criteria based on cardiac MRI. Compared with patients with cancer without myocarditis before ICI therapy, those with ICI-related myocarditis as a group had elevated global native T1, extracellular volume, and T2, along with the more frequent presence of LGE. LGE was also present in a small proportion (10%) of patients with cancer without myocarditis before ICI. While LGE was overall less common with ICI-related myocarditis than with viral myocarditis, septal and midwall LGE were more common with ICI-related myocarditis.The authors also found that the presence of septal LGE was predictive of increased MACE at 1 year, with an adjusted hazard ratio of 2.7. Moreover, it was suggested that the prognostic significance of septal LGE might be independent from troponin levels, which have previously been found to have predictive value for MACE. These results are discrepant with the prior study by Zhang et al (9), which found that LGE was not predictive of MACE. Moreover, in the prior study, which retrospectively included 103 patients drawn from an international multicenter registry with EMB or postmortem pathologic sample obtained in about half the patients, there was only modest correlation between cardiac MRI findings and histologic findings. However, in a further analysis of this international multicenter registry that incorporated parametric T1 and T2 mapping, Thavendiranathan et al (10) found that abnormal myocardial T1 values were present in 78% of patients with ICI-related myocarditis and abnormal T2 values in only 43%, and that higher T1 values carried independent prognostic value for MACE, while abnormal T2 values did not. Taking these findings together with the study by Cadour et al (2), it appears that the nonischemic myocardial injury criteria for myocarditis are not only more prevalent features of ICI-related myocarditis but also carry greater prognostic importance than criteria for myocardial edema. Of note, early corticosteroid therapy may explain the lower prevalence of T2 abnormalities in all these studies.A strength of the study by Cadour et al (2) is that scanner-specific calibration was performed for relaxation time and extracellular volume fraction measurements. The comparison with the two control groups is another major strength, and the finding of almost 10% of patients in the control group of patients before ICI therapy having LGE raises the clinical question of whether all patients who are started on an ICI should undergo a baseline cardiac MRI examination for reference. A drawback is that few patients underwent EMB to prove the diagnosis of ICI-associated myocarditis. However, EMB is invasive and suffers from sampling error, which can be a major limitation in a condition such as ICI-associated myocarditis, where the abnormality may be localized to one or a few regions. The authors instead made sure to use a specific uniform definition of myocarditis applicable to clinical trials of cancer immunotherapy.In conclusion, Cadour et al (2) have provided intriguing data that patients who develop myocarditis after checkpoint inhibitor therapy may present with different cardiac MRI features than patients with viral myocarditis or patients with cancer without myocarditis before ICI therapy, especially with respect to LGE prevalence, pattern, and localization. While the results are promising, further studies in larger cohorts are needed to confirm the diagnostic accuracy of these features. Moreover, the absence of specific cardiac MRI findings of ICI-related myocarditis does not exclude this diagnosis, and EMB may still be considered when the cardiac MRI results are not definitive and there is strong clinical suspicion of ICI-related myocarditis.Disclosures of Conflicts of Interest: R.R.E. No relevant relationships. A.P. No relevant relationships.References1. Tang J, Shalabi A, Hubbard-Lucey VM . Comprehensive analysis of the clinical immuno-oncology landscape. Ann Oncol 2018;29(1):84–91. Crossref, Medline, Google Scholar2. Cadour F, Cautela J, Rapacchi S, et al . Cardiac MRI features and prognostic value in immune checkpoint inhibitor–induced myocarditis. Radiology 2022;303(3):512–521. Link, Google Scholar3. Alexander W . The checkpoint immunotherapy revolution: what started as a trickle has become a flood, despite some daunting adverse effects; new drugs, indications, and combinations continue to emerge. P T 2016;41(3):185–191. Medline, Google Scholar4. Pennell DJ . Cardiovascular magnetic resonance. Circulation 2010;121(5):692–705. Crossref, Medline, Google Scholar5. Leiner T, Bogaert J, Friedrich MG, et al . SCMR position paper (2020) on clinical indications for cardiovascular magnetic resonance. J Cardiovasc Magn Reson 2020;22(1):76. Crossref, Medline, Google Scholar6. Saunderson CED, Plein S, Manisty CH . Role of cardiovascular magnetic resonance imaging in cardio-oncology. Eur Heart J Cardiovasc Imaging 2021;22(4):383–396. Crossref, Medline, Google Scholar7. Lyon AR, Yousaf N, Battisti NML, Moslehi J, Larkin J . Immune checkpoint inhibitors and cardiovascular toxicity. Lancet Oncol 2018;19(9):e447–e458. Crossref, Medline, Google Scholar8. Ferreira VM, Schulz-Menger J, Holmvang G, et al . Cardiovascular magnetic resonance in nonischemic myocardial inflammation: expert recommendations. J Am Coll Cardiol 2018;72(24):3158–3176. Crossref, Medline, Google Scholar9. Zhang L, Awadalla M, Mahmood SS, et al . Cardiovascular magnetic resonance in immune checkpoint inhibitor-associated myocarditis. Eur Heart J 2020;41(18):1733–1743. Crossref, Medline, Google Scholar10. Thavendiranathan P, Zhang L, Zafar A, et al . Myocardial T1 and T2 mapping by magnetic resonance in patients with immune checkpoint inhibitor-associated myocarditis. J Am Coll Cardiol 2021;77(12):1503–1516. Crossref, Medline, Google ScholarArticle HistoryReceived: Dec 28 2021Revision requested: Jan 12 2022Revision received: Jan 13 2022Accepted: Jan 18 2022Published online: Mar 01 2022Published in print: June 2022 FiguresReferencesRelatedDetailsAccompanying This ArticleCardiac MRI Features and Prognostic Value in Immune Checkpoint Inhibitor–induced MyocarditisMar 1 2022RadiologyRecommended Articles The Many Faces of Myocarditis: Role of Cardiac MRIRadiology2021Volume: 302Issue: 1pp. 70-71Postvaccine Myocarditis: A Risk Worth the Reward?Radiology2022Volume: 304Issue: 3pp. 563-565Cardiac MRI Features and Prognostic Value in Immune Checkpoint Inhibitor–induced MyocarditisRadiology2022Volume: 303Issue: 3pp. 512-521Cardiac MRI in Suspected Acute COVID-19 MyocarditisRadiology: Cardiothoracic Imaging2021Volume: 3Issue: 2Cardiac Abnormalities Depicted with MRI in COVID-19: Ongoing Concern for Myocardial InjuryRadiology2021Volume: 301Issue: 1pp. E371-E372See More RSNA Education Exhibits MRI Mapping in the study of Myocardial DiseaseDigital Posters2022Cardiotoxicity In Cancer Treatment: New Frontiers In The Multimodality Diagnostic ApproachDigital Posters2021Non-tumoral Cardiac Complications In Oncology PatientsDigital Posters2021 RSNA Case Collection Tuberculous pericardial abscess RSNA Case Collection2022Non-accidental anoxic brain injury RSNA Case Collection2021Primary HemochromatosisRSNA Case Collection2021 Vol. 303, No. 3 Metrics Altmetric Score PDF download

Purpose. Contrast-enhanced (CE) angiographic techniques, such as computed tomographic angiography (CE-CTA), are most commonly used for follow-up imaging after endovascular aneurysm repair. In this study, CE-CTA and non-CE QISS-MRA were compared for the first time for assessing endoleaks and aneurysms at follow-up after abdominal EVAR. Methods. Our study included 20 patients (17 male, median age 79.8 years) who underwent radial QISS-MRA and CE-CTA after EVAR at their first follow-up examination. Two interventional radiologists evaluated datasets from both techniques in each patient concerning presence of endoleaks, types of endoleaks, aneurysm diameter, and image quality. Interobserver and intermodal agreement were assessed with Cohen’s Kappa. Results. Image quality was rated as excellent or good for both modalities by both observers. Ferromagnetic embolization materials cause hyperdense artifacts in CE-CTA causing aneurysm sac diameter measurements to be inaccurate by up to 1 cm. Type 2 endoleaks with low-flow characteristics in CE-CTA were overlooked compared to radial QISS-MRA. Compared to CE-CTA, all endoleaks after abdominal EVAR were detected and classified correctly on QISS-MRA. The interobserver agreement between CE-CTA and QISS-MRA was almost perfect, except for type 2 endoleaks, where agreement was substantial. Intermodal aneurysm diameter correlate “very strongly” for both observers. Conclusions. Radial QISS-MRA is a contrast agent free technique for diagnosing and monitoring all types of endoleaks and aneurysms in patients after abdominal EVAR. It provides information about specific clinical questions concerning aneurysm diameter and presence and types of endoleaks without radiation exposure and the side effects associated with iodine-based contrast agents.

PurposeTo report a quantitative time‐of‐flight (qTOF) MRA technique for simultaneous luminal and hemodynamic evaluation of the intracranial arteries.MethodsImplemented using a thin overlapping slab 3D stack‐of‐stars based 3‐echo FLASH readout, qTOF was tested in a flow phantom and for imaging the intracranial arteries of 10 human subjects at 3 Tesla. Display of the intracranial arteries with qTOF was compared to resolution‐matched and scan time‐matched standard Cartesian 3D time‐of‐flight (TOF) MRA, whereas quantification of mean blood flow velocity with qTOF, done using a computer vision‐based inter‐echo image analysis procedure, was compared to 3D phase contrast MRA. Arterial‐to‐background contrast‐to‐noise ratio was measured, and intraclass correlation coefficient was used to evaluate agreement of flow velocities.ResultsFor resolution‐matched protocols of similar scan time, qTOF portrayed the intracranial arteries with good morphological correlation with standard Cartesian TOF, and both techniques provided superior contrast‐to‐noise ratio and arterial delineation compared to phase contrast (20.6 ± 3.0 and 37.8 ± 8.7 vs. 11.5 ± 2.2, P < .001, both comparisons). With respect to phase contrast, qTOF showed excellent agreement for measuring mean flow velocity in the flow phantom (intraclass correlation coefficient = 0.981, P < .001) and good agreement in the intracranial arteries (intraclass correlation coefficient = 0.700, P < .001). Stack‐of‐stars data sampling used with qTOF eliminated oblique in‐plane flow misregistration artifacts that were seen with standard Cartesian TOF.ConclusionqTOF is a new 3D MRA technique for simultaneous luminal and hemodynamic evaluation of the intracranial arteries that provides significantly greater contrast‐to‐noise ratio efficiency than phase contrast and eliminates misregistration artifacts from oblique in‐plane blood flow that occur with standard 3D TOF.