Total-body MR-imaging in oncology

Schaefer, Juergen F.; Schlemmer, Heinz Peter

doi:10.1007/s00330-006-0199-0

Cited by 64 publications

(40 citation statements)

References 79 publications

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“…The advent of parallel imaging techniques, such as generalized autocalibrating, partially parallel acquisitions (143) and sensitivity encoding (144) has accelerated image acquisition times, thus allowing whole-body MRI examinations with high spatial resolution (145). Initial results show that whole-body MRI is a promising modality in oncology, especially for the detection of metastases and hematologic malignancies (146). Performing whole-body MRI similarly to a CT examination, with continuous table motion, is likely to improve time efficiency (147).…”

Section: Whole-body Mrimentioning

confidence: 99%

Latest Advances in Molecular Imaging Instrumentation

Pichler¹,

Wehrl²,

Judenhofer³

2008

J Nucl Med

194

110

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This review concentrates on the latest advances in molecular imaging technology, including PET, MRI, and optical imaging. In PET, significant improvements in tumor detection and image resolution have been achieved by introducing new scintillation materials, iterative image reconstruction, and correction methods. These advances enabled the first clinical scanners capable of time-of-flight detection and incorporating point-spread-function reconstruction to compensate for depth-of-interaction effects. In the field of MRI, the most important developments in recent years have mainly been MRI systems with higher field strengths and improved radiofrequency coil technology. Hyperpolarized imaging, functional MRI, and MR spectroscopy provide molecular information in vivo. A special focus of this review article is multimodality imaging and, in particular, the emerging field of combined PET/MRI. PETi s a high-performance imaging technology that can image the whole-body distribution of positron-emitting biomarkers with high sensitivity. The invention of PET dates back more than 30 y. However, the acceptance of PET as a routine clinical diagnostic tool has been hampered by the need for an on-site cyclotron and a radiochemistry unit for the production of the short-lived radiotracers (1-7). With the availability of commercial radiopharmacies that supply PET probes and with the relatively broad insurance coverage for a variety of clinical indications, the number of PET centers now totals more than 2,000 worldwide.Major technologic milestones in the development of PET include the discovery of faster and brighter scintillators such as lutetium oxyorthosilicate (LSO), gadolinium oxyorthosilicate, and lutetium yttrium oxyorthosilicate. Furthermore, the continuing development of the detectors, progressing from one-to-one scintillator-to-photomultiplier-tube (PMT) coupling (8,9) to advanced block and Anger readout schemes, helps to limit the costs of a PET scanner by providing a multiplexed readout and reduced electronic channels (10-13).The use of faster scintillators enabled the transition from 2-dimensional data acquisitions for whole-body PET, using lead or tungsten collimators as septa (14-16), to 3-dimensional (3D) acquisitions (17). However, approximately an 8-fold increase in detection sensitivity is accompanied by an increased fraction of random and scattered photon events leading to degradation of image quality if not corrected during image reconstruction (18). This degradation effectively reduces the increase in sensitivity from a factor of 8 to approximately 5-fold. To achieve high-quality and quantitative PET data, various image reconstruction techniques have evolved (19). One simple approach is filtered backprojection, which is computationally fast but results in poor image quality if the count statistics of the available PET data are inadequate. Better image quality and improved spatial resolution are achieved by iterative methods such as ordered-subset expectation maximization or maximumlikelihood expectation maximiza...

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Section: Whole-body Mrimentioning

confidence: 99%

Latest Advances in Molecular Imaging Instrumentation

Pichler¹,

Wehrl²,

Judenhofer³

2008

J Nucl Med

194

110

View full text Add to dashboard Cite

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“…A more recent approach involved image acquisition with the table moving continuously through the scanner at a constant velocity (sliding multislice (SMS)) [14][15][16] . Moving-table acquisitions have been investigated in detail in magnetic resonance angiography (MRA) and whole body MRI 15,16 , as well as for screening and staging in 100 oncology 12,17 . Investigations into its utilisation in radiotherapy is limited 13 .…”

Section: Introductionmentioning

confidence: 99%

Continuous table acquisition MRI for radiotherapy treatment planning: Distortion assessment with a new extended 3D volumetric phantom

et al. 2015

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(2015). Continuous table acquisition MRI for radiotherapy treatment planning: Distortion assessment with a new extended 3D volumetric phantom. Medical Physics, 42 (4), 1982Physics, 42 (4), -1991 Continuous table acquisition MRI for radiotherapy treatment planning: distortion assessment with a new extended 3D volumetric phantom AbstractPurpose: Accurate geometry is required for radiotherapy treatment planning (RTP). When considering the use of magnetic resonance imaging (MRI) for RTP, geometric distortions observed in the acquired images should be considered. While scanner technology and vendor supplied correction algorithms provide some correction, large distortions are still present in images, even when considering considerably smaller scan lengths than those typically acquired with CT in conventional RTP. This study investigates MRI acquisition with a moving table compared with static scans for potential geometric benefits for RTP. Methods: A full field of view (FOV) phantom (diameter 500 mm; length 513 mm) was developed for measuring geometric distortions in MR images over volumes pertinent to RTP. The phantom consisted of layers of refined plastic within which vitamin E capsules were inserted. The phantom was scanned on CT to provide the geometric gold standard and on MRI, with differences in capsule location determining the distortion. MRI images were acquired with two techniques. For the first method, standard static table acquisitions were considered. Both 2D and 3D acquisition techniques were investigated. With the second technique, images were acquired with a moving table. The same sequence was acquired with a static table and then with table speeds of 1.1 mm/s and 2 mm/s. All of the MR images acquired were registered to the CT dataset using a deformable B-spline registration with the resulting deformation fields providing the distortion information for each acquisition. Results: MR images acquired with the moving table enabled imaging of the whole phantom length while images acquired with a static table were only able to image 50%-70% of the phantom length of 513 mm. Maximum distortion values were reduced across a larger volume when imaging with a moving table. Increased table speed resulted in a larger contribution of distortion from gradient nonlinearities in the through-plane direction and an increased blurring of capsule images, resulting in an apparent capsule volume increase by up to 170% in extreme axial FOV regions. Blurring increased with table speed and in the central regions of the phantom, geometric distortion was less for static table acquisitions compared to a table speed of 2 mm/s over the same volume. Overall, the best geometric accuracy was achieved with a table speed of 1.1 mm/s. Conclusions: The phantom designed enables full FOV imaging for distortion assessment for the purposes of RTP. MRI acquisition with a moving table extends the imaging volume in the z direction with reduced distortions which could be useful particularly if considering MR-only planning. If utilizing MR image...

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“…To reach these requirements along with the advance of magnetic resonance imaging (MRI) techniques since 2004, the use of Whole Body (WB) images has been increasing on oncology patients and multifocal diseases [8] as a new alternative to the gold standard PET-CT which provides full body information despite radiation exposure and low availability [6 • ] (Fig. 1).…”

Section: Wb-mri Use In Pediatricsmentioning

confidence: 99%

Whole Body MRI and Diffusion Weighed Images in Pediatric Oncology: Lymphomas and Several Others Tumors

Schiavon

Lederman

2014

Curr Radiol Rep

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Cancer in a pediatric population represents the majority of non-related to trauma deaths. In most developed and emerging countries there is a need for early and accurate imaging detection, usually with fast examinations protocols, and no or low radiation exposure to avoid a secondary radiation induced neoplasia. The advance of magnetic resonance imaging techniques permitting the use of whole body images on oncology patients and multifocal diseases and the use of diffusion weight images DWI techniques allow additional metabolic information for WB-MRI with growing evidence that the disease metabolic activity is correlated with cellularity in some tumors. This permits DWI sequences and suggests tumor activity with the therapy response as an alternative to PET-CT. WB-MRI has proved to be more sensitive than scintigraphy in detecting both marrow and non-marrow involvement on lymphoma patients and can be a very good alternative to those who cannot undergo a PET-CT. Other small cell neoplasms such as Ewing family, neuroblastoma and some sarcomas also have been effective evaluated by WB-MRI. On palliative care patients, WB-MRI plays a rule on detecting lesions that can cause pain or pressure over vital structures. In conclusion, WB-MRI has been proved an extremely useful method on multifocal diseases and oncology with the same routine MR contraindications and should be, respecting the limitations inherent to any radiology method, accepted as another powerful tool especially in pediatric oncology. It can be used to avoid radiation exposure related disease and could be more available to these patients.

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Total-body MR-imaging in oncology

Cited by 64 publications

References 79 publications

Latest Advances in Molecular Imaging Instrumentation

Latest Advances in Molecular Imaging Instrumentation

Continuous table acquisition MRI for radiotherapy treatment planning: Distortion assessment with a new extended 3D volumetric phantom

Whole Body MRI and Diffusion Weighed Images in Pediatric Oncology: Lymphomas and Several Others Tumors

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