Faculty Bibliography

Purpose or Case Report: MRI scans are long, and scan durations are unpredictable. Combined with challenges of inter-departmental coordination, this leads to poorer operational efficiency, increased need for sedation (especially in a pediatric population), increased wait time, and overall poorer patient care. There is a need for active, automatic tracking of scan log in a MRI machine to 1) determine operational efficiency, 2)disease specific scan information, 3) identifying patient specific scan metrics.Currently, there exist no customizable open-source solution that can automatically obtain information from MRI scanners. The purpose of this study is to demonstrate implementation of a novel, customizable QI tool that can automatically extract scan log data from a MRI scanner in a pediatric setting. Methods & Materials: 'LogServer' (https://urldefense.proofpoint.com/v2/url?u=https- 3A__yarra.rocks_doc_server_yarralogserver_&d=DwIBAg&c=j5oPpO0eBH1iio48DtsedeElZfc04rx3ExJHeII ZuCs&r=Vk3H8b3- Ln6FkaEcmPdAL_q5c3LYlceRekv38KQMQsQ&m=Tb1QWQ0Q507Fc3Dh_QTwkGuxccnOSDM2YwFar1Khjs w&s=PhuhMD2zw-zB71kInlTbMr387L46mQGBa5ITaQLBNBc&e=) was developed for use in Siemens MRI machines. This uses the 'Yarra' framework-an open source framework for complex MRI reconstructions. 'LogServer' monitors sequences, parses MRI sequences into discrete exams, generates 'EPIC-formatted' patient names, monitors scanner health, and tags exams with body region information. All extracted data were stored in 'PostgreSQL'-an open source database. 'ReDASH', an open source dashboard, was used to create customizable dashboards. In this study, for a clinical MRI scanner, we looked at 1) Daily scanner efficiency, defined as ratio of total hours scanner unused time to total hours (8am-7pm workday), and 2) Scan efficiency, defined as time when scanner was running to total time when the patient was on table.
Result(s): 'LogServer' was successfully able to automatically extract scan logs from MRI machines on an hourly basis, extract all relevant information, and visualize them in needed format using a remote PHI secure web browser. Figure 1 (https://urldefense.proofpoint.com/v2/url?u=https-3A__drive.google.com_open-3Fid- 3D1fvyrSjq96EcHaAv9GenX1&d=DwIBAg&c=j5oPpO0eBH1iio48DtsedeElZfc04rx3ExJHeIIZuCs&r=Vk3H8b 3- Ln6FkaEcmPdAL_q5c3LYlceRekv38KQMQsQ&m=Tb1QWQ0Q507Fc3Dh_QTwkGuxccnOSDM2YwFar1Khjs w&s=nrP1MlFbOaNtb6QumtVnX4lmEegx9lV5WKKnySkiBi8&e= v4b070tFP3l) demonstrates the scanner schedule for any given day. Figure 2 (https://urldefense.proofpoint.com/v2/url?u=https-3A__drive.google.com_open-3Fid- 3D1O7fxAIhWrAeqFVr3qRW&d=DwIBAg&c=j5oPpO0eBH1iio48DtsedeElZfc04rx3ExJHeIIZuCs&r=Vk3H8b 3- Ln6FkaEcmPdAL_q5c3LYlceRekv38KQMQsQ&m=Tb1QWQ0Q507Fc3Dh_QTwkGuxccnOSDM2YwFar1Khjs w&s=oPNXA1NYelrynP08LY1m5MRqoqIgTNPRYaeuh40P1xI&e= 5QyMGaN3F0mnX) shows the scan metrics for a selected patient, including total scan time, idle time during a scan session, as well time for adjustments in scanner. Our daily scanner efficiency for a week was 64% while scan efficiency was 76.3 +/- 10%.
Conclusion(s): We demonstrated a robust customizable QI tool that lets continuous automatic monitoring of MRI scanner. This is a useful tool for hospital administrators, clinical managers, clinical leaders in their informed decision making

BACKGROUND:T1-weighted post-contrast MRI is essential in brain protocols. We demonstrate the feasibility and utility of a 3D non-Cartesian radial acquisition in children. PURPOSE/OBJECTIVE:To compare bulk motion artifacts, image quality, and lesion conspicuity in 3D T1-weighted post-contrast brain MRI between a new fat-suppressed radial gradient-echo and a traditional non-fat-suppressed inversion-recovery Cartesian gradient-echo sequence. MATERIAL AND METHODS/METHODS:Images from 53 patients acquired at 3 Tesla were compared. Three radiologists rated the images in three categories, including the presence of bulk motion and whether it impacted diagnosis, whether one sequence was preferred over the other in overall image quality and conspicuity of vascular structures and lesions, and whether diagnosis was possible if only the new fat-suppressed radial acquisition was obtained. RESULTS:The Fleiss' kappa for inter-rater agreement was 0.67 for bulk motion and 0.54 for sequence preference. Of the 53 cases, 56% were identified to have significant motion on conventional imaging, while only 13% had motion artifacts on the radial acquisition (p < 0.05). There were no cases where motion was seen on the radial acquisition but not on conventional imaging. Both sequences were equally preferred in 87% of the cases. All radiologists agreed that the radial approach had lower gray-white matter contrast than the conventional inversion-recovery method, but preferred the former for making diagnosis in uncooperative patients. CONCLUSION/CONCLUSIONS:We demonstrate the potential utility of a fat-suppressed 3D T1-weighted post-contrast brain gradient-echo sequence in children. The technique is useful in non-sedate pediatric imaging due to its reduced sensitivity to bulk motion.

OBJECTIVE:The purpose of this study is to increase the value of MRI by reengineering the MRI workflow at a new imaging center to shorten the interval (i.e., turnaround time) between each patient examination by at least 5 minutes. MATERIALS AND METHODS/METHODS:The elements of the MRI workflow that were optimized included the use of dockable tables, the location of patient preparation rooms, the number of doors per scanning room, and the storage location and duplication of coils. Turnaround times at the new center and at two existing centers were measured both for all patients and for situations when the next patient was ready to be brought into the scanner room after the previous patient's examination was completed. RESULTS:Workflow optimizations included the use of dockable tables, dedicated patient preparation rooms, two doors in each MRI room, positioning the scanner to provide the most direct path to the scanner, and coil storage in the preparation rooms, with duplication of the most frequently used coils. At the new imaging center, the median and mean (± SD) turnaround times for situations in which patients were ready for scanning were 115 seconds (95% CI, 113-117 seconds) and 132 ± 72 seconds (95% CI, 129-135 seconds), respectively, and the median and mean turnaround times for all situations were 141 seconds (95% CI, 137-146 seconds) and 272 ± 270 seconds (95% CI, 263-282 seconds), respectively. For existing imaging centers, the median and mean turnaround times for situations in which patients were ready for scanning were 430 seconds (95% CI, 424-434 seconds) and 460 ± 156 seconds (95% CI, 455-465 seconds), respectively, and the median and mean turnaround times for all situations were 481 seconds (95% CI, 474-486 seconds) and 537 ± 219 seconds (95% CI, 532-543 seconds), respectively. CONCLUSION/CONCLUSIONS:The optimized MRI workflow resulted in a mean time savings of 5 minutes 28 seconds per patient.

PURPOSE/OBJECTIVE:MRI methods that have reduced sensitivity to motion are attractive in pediatric applications. In spine imaging, physiologic motion such as respiration and cerebrospinal fluid pulsation can hamper diagnostic image quality. We compare a 3D T1-weighted non-Cartesian radial acquisition with a conventional Cartesian 2D turbo-spin-echo (TSE) acquisition in axial post-contrast spine imaging at 3T. METHODS:Thirty-two patients (mean age 12.2 ± 5.3 years) scheduled for routine clinical spine exams with contrast were enrolled. Three pediatric neuroradiologists compared the two sequences and assessed the presence of motion, the conspicuity of nerve roots, and whether one of the sequences was preferred in visualizing pathology using Likert scales. RESULTS:The Fleiss' kappa statistic for inter-rater agreement was 0.29 (95% confidence interval, 0.15-0.43) for the presence of motion, 0.30 (0.21-0.38) for conspicuity, and 0.37 (0.19-0.55) for sequence preference. Radial images were less sensitive to motion than TSE (p < 0.01). Motion and consequent artifacts were present in all TSE cases, while it was absent in 51% of the radial cases. In depicting nerve roots, radial images were superior in the cervical (p < 0.05), thoracic (p < 0.01), and lumbar spines (p < 0.01). Lastly, in 28 of the 32 patients who demonstrated contrast-enhancing pathology, radial images were preferred in 51% of the cases, while both sequences were equally preferred in 41% of the cases. CONCLUSION/CONCLUSIONS:We demonstrate the potential utility of radial MRI in post-contrast spine imaging. The free-breathing method is robust in generating diagnostic image quality and is superior in visualizing nerve roots and extramedullary metastases than traditional Cartesian TSE acquisitions.

PURPOSE/OBJECTIVE:Magnetic resonance imaging protocols for the assessment of quantitative information suffer from long acquisition times since multiple measurements in a parametric dimension are required. To facilitate the clinical applicability, accelerating the acquisition is of high importance. To this end, we propose a model-based optimization framework in conjunction with undersampling 3D radial stack-of-stars data. THEORY AND METHODS/UNASSIGNED:maps are generated from subsampled data by employing model-based reconstruction combined with a regularization functional, coupling information from the spatial and parametric dimension, to exploit redundancies in the acquired parameter encodings and across parameter maps. To cope with the resulting non-linear, non-differentiable optimization problem, we propose a solution strategy based on the iteratively regularized Gauss-Newton method. The importance of 3D-spectral regularization is demonstrated by a comparison to 2D-spectral regularized results. The algorithm is validated for the variable flip angle (VFA) and inversion recovery Look-Locker (IRLL) method on numerical simulated data, MRI phantoms, and in vivo data. RESULTS:maps from accelerated 3D in vivo measurements, e.g. 1.8 s/slice with the VFA method, are in high accordance with fully sampled reference reconstructions. CONCLUSIONS:from highly undersampled radial data by exploiting structural similarities in the imaging volume and across parameter maps.

Purpose or Case Report: Free-breathing MRI scans are attractive in pediatric imaging as they reduce the need for sedation and breath-holds. In this work, we evaluate a 3D T1w radial "stack of stars" gradient echo (GRE) acquisition (RAVERAdial Volumetric Encoding) in post-contrast abdomen and spine protocols and compare results with conventional Cartesian MRI of similar spatial resolution and volume coverage. Methods & Materials: Studies were performed on a 3T Siemens Prisma. With radial MRI, data are acquired along kspace spokes during repetitions of the sequence. Consecutive spokes are rotated in-plane by the golden-angle (111.25 deg) to maximize k-space coverage. The center of k-space is oversampled and this feature affords RAVE's robustness to motion. When coupled with compressed sensing and parallel imaging, the radial data further yields dynamic images, (i.e., during contrast passage). We have evaluated free-breathing RAVE in 20 patients referred for non-sedated abdominal and spine MRI exams with contrast. In the abdomen, we have acquired RAVE in both axial and coronal orientations (i.e., liver, enterography). In the spine, we have acquired RAVE in the axial plane. Three radiologists compared RAVE to conventional breath-hold GRE in abdomen scans and free-breathing fast-spinecho (FSE) images in the spine. A 3-point scale was used to evaluate diagnostic image quality:-1=RAVE is superior, 0=equivalent, +1=RAVE is inferior. Results: In all cases, RAVE images were considered robust to respiratory, cardiac, and gastrointestinal motion, and no artifacts that impacted diagnostic image quality were noted. In the spine, RAVE was consistently superior to FSE (p<0.01) in delineating nerve tracts and roots against CSF. In the abdomen, RAVE was comparable to breath-hold GRE scans. Fig 1 shows a series of cervical, thoracic, and lumbar spine comparisons between FSE and RAVE in a 14y patient. Note the lack of motion-related artifacts in RAVE, without the use saturation bands. Fig 2 shows coronal RAVE dynamic frames ~15s apart, highlighting contrast uptake, in a 10y patient. A breath-hold post-contrast GRE image is shown for comparison. Figure 3 shows pre-and postcontrast axial RAVE images in a 14y patient. Conclusions: Our data demonstrates the potential utility of a free-breathing accelerated 3D T1w RAVE sequence in unsedated pediatric imaging. The technique is particularly useful in patients who are unable to follow breath-hold instructions and suspend respiration, and it is 30-50% faster in scan time than conventional methods

Purpose or Case Report: With increasing interest in rapid MRIs aimed to reduce sedation in pediatric imaging, the purpose of this study was to evaluate a 3D golden-angle radial "stack of stars" gradient echo scan (i.e., RAVE-RAdial Volumetric Encoding) and to compare results with a conventional 3D inversion recovery sequence in post contrast brain imaging. Methods & Materials: Studies were performed on a 3T Siemens Prisma system using either a 20 or 64-channel head array. Unlike traditional Cartesian acquisitions, MRI data in RAVE is acquired with consecutive k-space spokes that are rotated by the golden-angle (111.25 deg) to maximize k-space coverage efficiency. As a result of the radial trajectory, the center of k-space is oversampled and this feature affords RAVE's robustness to motion. When coupled with compressed sensing and parallel imaging, RAVE data can further yield time-resolved images during contrast passage. We evaluated RAVE in 20 patients (average age: 12.5y, range 2.2-21y) referred for brain MRI exams with contrast. Upon injection of standard dose contrast media (Gadavist), data from a RAVE acquisition and a conventional 3D IR-GRE (i.e., MPRAGE) were implemented (MPRAGE first). The two scans were matched in 1 mm native isotropic spatial resolution and volume coverage. On average, the MPRAGE acquisition took 5-6 minutes to complete, whereas the RAVE scan is ~25-30% faster. Three radiologists independently compared the data in terms of conspicuity of contrast-enhancing lesions and diagnostic image quality with respect to motion-related artifacts. A 3-point scale was used:-1=RAVE is superior, 0=RAVE and MPRAGE are equivalent, +1=MPRAGE is superior. Results: All evaluators found the RAVE with MPRAGE reformats to be similar when presenting contrast-enhanced details in 15 cases (score= 0). In the remaining 5, RAVE was preferred (score=-1). RAVE was notably more resistant to subject motion and pulsation artifacts. No significant artifacts were noted in RAVE. Figures 1 and 2 show data in non-sedated 13y and 11y old patients, respectively, with significant head movements. Figure 3 illustrates time-resolved images from RAVE in a 7y old, 20s apart, showing an enhancing lesion (arrow). Conclusions: Our study demonstrates the potential clinical utility of an accelerated 3D T1-weighted RAVE MRI sequence in unsedated pediatric brain imaging. The complementary technique is particularly useful in patients prone to head (and body) motion. Further evaluation in neonatal imaging and body and spine applications are warranted

PURPOSE/OBJECTIVE:-weighted images from a single scan and allows for free-breathing acquisition. THEORY AND METHODS/UNASSIGNED:-weighted gradient-echo (GRE) data. Improved robustness is achieved by extracting a respiratory signal from the GRE data and using it for motion-weighted reconstruction. RESULTS:-weighted Dixon acquisition is possible. CONCLUSION/CONCLUSIONS:-weighted imaging in a single scan. In addition to free-breathing abdominal examination, it promises value for clinical applications that are frequently affected by motion artifacts.

PURPOSE/OBJECTIVE:To validate an optimal 12-fold accelerated real-time cine MRI pulse sequence with radial k-space sampling and compressed sensing (CS) in patients at 1.5T and 3T. METHODS:We used two strategies to reduce image artifacts arising from gradient delays and eddy currents in radial k-space sampling with balanced steady-state free precession readout. We validated this pulse sequence against a standard breath-hold cine sequence in two patient cohorts: a myocardial infarction (n = 16) group at 1.5T and chronic kidney disease group (n = 18) at 3T. Two readers independently performed visual analysis of 68 cine sets in four categories (myocardial definition, temporal fidelity, artifact, noise) on a 5-point Likert scale (1 = nondiagnostic, 2 = poor, 3 = adequate or moderate, 4 = good, 5 = excellent). Another reader calculated left ventricular (LV) functional parameters, including ejection fraction. RESULTS:Compared with standard cine, real-time cine produced nonsignificantly different visually assessed scores, except for the following categories: 1) temporal fidelity scores were significantly lower (P = 0.013) for real-time cine at both field strengths, 2) artifacts scores were significantly higher (P = 0.013) for real-time cine at both field strengths, and 3) noise scores were significantly (P = 0.013) higher for real-time cine at 1.5T. Standard and real-time cine pulse sequences produced LV functional parameters that were in good agreement (e.g., absolute mean difference in ejection fraction <4%). CONCLUSION/CONCLUSIONS:This study demonstrates that an optimal 12-fold, accelerated, real-time cine MRI pulse sequence using radial k-space sampling and CS produces good to excellent visual scores and relatively accurate LV functional parameters in patients at 1.5T and 3T. Magn Reson Med 79:2745-2751, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

PURPOSE/OBJECTIVE:To compare patellar instability with magnetic resonance imaging analysis using continuous real-time radial gradient-echo (GRE) imaging in the assessment of symptomatic patients and asymptomatic subjects. METHODS:Symptomatic patients with suspected patellofemoral maltracking and asymptomatic volunteers were scanned in real time by a radial 2-dimensional GRE sequence at 3 T in axial orientation at the patella level through a range of flexion-extension. The degree of lateral maltracking, as well as the associated tibial tubercle-trochlear groove distance and trochlea depth, was measured. Patellar lateralization was categorized as normal (≤2 mm), mild (>2 to ≤5 mm), moderate (>5 to ≤10 mm), or severe (>10 mm). The patellofemoral cartilage was also assessed according to the modified Outerbridge grading system. RESULTS:The study included 20 symptomatic patients (13 women and 7 men; mean age, 36 ± 12.8 years) and 10 asymptomatic subjects (3 women and 7 men; mean age, 33.1 years). The mean time to perform the dynamic component ranged from 3 to 7 minutes. Lateralization in the symptomatic group was normal in 10 patients, mild in 1, moderate in 8, and severe in 1. There was no lateral tracking greater than 3 mm in the volunteer group. Lateral maltracking was significantly higher in symptomatic patients than in asymptomatic subjects (4.4 ± 3.7 mm vs 1.5 ± 0.71 mm, P = .007). Lateral tracking significantly correlated with tibial tubercle-trochlear groove distance (r = 0.48, P = .006). There was excellent agreement on lateral tracking between the 2 reviewers (intraclass correlation coefficient, 0.979; 95% confidence interval, 0.956-0.990). CONCLUSIONS:The inclusion of a dynamic radial 2-dimensional GRE sequence is a rapid and easily performed addition to the standard magnetic resonance imaging protocol and allows dynamic quantitative assessment of patellar instability and lateral maltracking in symptomatic patients. With a paucity of reported data using this technique confirming that these results reach clinical significance, future work is required to determine how much lateral tracking is clinically significant. LEVEL OF EVIDENCE/METHODS:Level III, case control.