Automated MR Scanner Workflow of combined Chest, Abdomen and Pelvis Exams: First Clinical Experience
Caecilia S Reiner1,2, Bernd Kuehn3, Daniel Nanz2, Berthold Kiefer3, and Gustav Andreisek1,2

1Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Zurich, Switzerland, 2University of Zurich, Zurich, Switzerland, 3Oncology Application Predevelopment, Siemens Healthcare, Erlangen, Germany

Synopsis

An increasing demand for time-efficient and standardized MRI drives the development of automated MRI-workflows. The purpose of this study was to evaluate the feasibility of such a novel automated scanner-workflow for multi-station MRI. The scanner automatically detects the body regions selected and sequences are automatically adjusted to patient’s size and breath-holding capacity to generate optimal image quality. In 20 patients scanned with a multi-station protocol (chest, abdomen, and/or pelvis), image quality was good to excellent and complete body region coverage was achieved in 95% of patients. This nearly “single-button” automated multi-station MRI could open new possibilities in the diagnostic process.

Background and Purpose:

Time- and cost-efficiency are among the major challenges in clinical magnetic resonance imaging (MRI), mainly driven by the shortening of reimbursement in most health care systems. At the same time, there is an increasing overall demand for higher quality of MRI exams regarding the comparability of exams, i.e. important for primary and/or follow-up studies in oncologic patients. To address these challenges, several vendors and researchers are developing automated scanner workflows for clinical MRI systems. The hypothesis is that these workflows allow a standardized and time-efficient use and provide a robust image quality at only little user interaction. The purpose of this study was to evaluate the feasibility of a novel automated scanner workflow for multi-station MRI such as chest, abdomen and pelvis, gauge the reliability of the algorithm with regard to completeness of anatomical coverage, and assess overall image quality and severity of imaging artifacts.

Material and Methods

Patient cohort: Twenty oncologic patients (10 women, 10 men; mean age, 49 ys, range, 20-75 ys) were examined on a 3 T MRI scanner (MAGNETOM Skyra, Siemens Healthcare) using a Whole-Body Dot Engine supporting an automated multi-station scanner workflow. Combined exams of chest, abdomen and/or pelvis were performed in 13 patients for oncologic follow-up, in three for primary staging, and in four for tumor screening. Image acquisition: The Whole-Body Dot Engine automatically detects landmarks like lung apex, lung recessus, diaphragm, liver apex, iliac bone on a fast low resolution whole body scout, which is acquired during moving table. Based on this the body regions selected for scanning, namely chest, abdomen and/or pelvis are segmented (Figure 1). Sequence parameters are automatically adjusted in order to ensure proper coverage of the body regions of interest. Additionally, the Whole-Body Dot Engine uses an anticipated patient’s breath-hold capacity to automatically adjust the imaging protocols in body regions where breathhold is required generating optimal image quality. In this study, the breath-hold capacity was set to 20 sec. The protocol included coronal and transverse T2-weighted single-shot turbo-spin-echo (HASTE) (TR/TE, 1230/92 ms; flip angle, 160°; slice thickness (ST)/spacing, 5/1mm; matrix, 256x256), transverse single-shot diffusion-weighted echo-planar imaging with slice-specific shim optimization (EPI-DWI, iShim (1)) (TR/TE, 6100/56ms; flip angle, 90°; ST/spacing, 5/1mm; matrix 128x128), and transverse T1-weighted pre- and post-contrast 3D spoiled gradient-echo 2-point Dixon (VIBE) (TR/TE, 4.27/1.28ms; flip angle, 12°; ST 3mm; matrix 320x192) pre- and post-contrast acquisitions (delay: chest 35 sec, abdomen 70 sec, pelvis 90 sec after injection of 0.1mmol/kg bodyweight gadoterate meglumine, Dotarem, Guerbet). The cranio-caudal coverage per block was adjusted to 400 mm. Image evaluation: The scans were evaluated for overall image quality (IQ) (5=excellent, 4=good, 3=moderate, 2=poor, 1=non-diagnostic) and artifacts (5=no artifacts, 4=mild artifacts, 3=moderate artifacts, 2=severe artifacts, 1=non-diagnostic) on a 5-point scale by a board-certified abdominal radiologist with 8 years of experience. The image acquisition time was noted as well as whether the coverage of the targeted body region was complete. Descriptive statistics were performed.

Results

In 16 patients, abdomen and pelvis were scanned, in three patients chest, abdomen and pelvis, and in one patient only chest. Overall in all but one patient (19 of 20, 95%), the selected body regions were covered completely by the automated algorithm, with exception of the DWI, which did not cover the sub-diaphragmatic part of the liver in four patients (4 of 20, 20%). The mean score for overall IQ was 4.6 ± 0.49 standard deviation (SD) and for artifacts was 4.2 ± 0.57 SD. In two patients (2 of 20, 10%), mild respiratory motion artifacts were observed on T1-weighted post-contrast images (Figure 2). The mean examination time was 26.3±3.4min for chest, abdomen and pelvis, 21.2 ± 3.4 min for abdomen and pelvis, and 14.1min for chest only.

Conclusion

MR scanning with the automated Whole-Body Dot Engine results in good to excellent image quality within a reasonable total examination time with only small patient dependent variations. A nearly “single-button protocol” for standardized fast, reproducible, and automated workflow of chest, abdomen, and pelvis, could open new possibilities in the diagnostic process. However, further comparison studies with traditional manual scan modes need to be performed to support our preliminary experience.

Acknowledgements

None

References

1. Alto Stemmer et. al.: Combination of integrated slice-specific dynamic shimming and pixel-wise unwarping of residual EPI distortions. Proc. Intl. Soc. Mag. Reson. Med. 23 (2015) #3729

Figures

(a) Fast low resolution whole body scout with automatically segmented abdomen and pelvis for multi-station scanning. (b) Coronal T2 single-shot turbo-spin-echo images with automatically segmented abdomen and pelvis split into two blocks for the transverse T1-weighted sequence (c) with an acquisition time of 15 sec for each lying within the preset 20-sec breathhold capacity. The cranio-caudal coverage per block is set to 400 mm and is adjusted to patient size and breathhold capacity.

T1-weighted post-contrast 3D spoiled gradient-echo 2-point Dixon sequences with excellent image quality (a) and with mild respiratory motion artifacts (b).



Proc. Intl. Soc. Mag. Reson. Med. 24 (2016)
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