Review of potential improvements using MRI in the radiotherapy workflow

Torresin, A.; Brambilla, M.G.; Monti, A.F.; Moscato, Alessio; Brockmann, Marc A.; Schad, Lothar R.; Attenberger, Ulrike; Lohr, Frank

doi:10.1016/j.zemedi.2014.11.003

Cited by 15 publications

(14 citation statements)

References 67 publications

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“…All these features substantiate the importance of MRI as a technique complementary to CT for its application in RTP [5] and open perspectives for this imaging modality to serve as a platform for new types of agents for combined imaging and therapy, called theranostics [6]. This review focuses on the role of MRI for different types of RT ( Figure 1) and surveys the most important types of MRI CAs that have been developed to enhance the effects of external RT, enable monitoring of delivery and distribution of the internal radiotherapeutics, and evaluate the therapeutic outcome.…”

Section: Introductionsupporting

confidence: 59%

Potential of MRI in Radiotherapy Mediated by Small Conjugates and Nanosystems

2019

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Radiation therapy has made tremendous progress in oncology over the last decades due to advances in engineering and physical sciences in combination with better biochemical, genetic and molecular understanding of this disease. Local delivery of optimal radiation dose to a tumor, while sparing healthy surrounding tissues, remains a great challenge, especially in the proximity of vital organs. Therefore, imaging plays a key role in tumor staging, accurate target volume delineation, assessment of individual radiation resistance and even personalized dose prescription. From this point of view, radiotherapy might be one of the few therapeutic modalities that relies entirely on high-resolution imaging. Magnetic resonance imaging (MRI) with its superior soft-tissue resolution is already used in radiotherapy treatment planning complementing conventional computed tomography (CT). Development of systems integrating MRI and linear accelerators opens possibilities for simultaneous imaging and therapy, which in turn, generates the need for imaging probes with therapeutic components. In this review, we discuss the role of MRI in both external and internal radiotherapy focusing on the most important examples of contrast agents with combined therapeutic potential.

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Section: Introductionsupporting

confidence: 59%

Potential of MRI in Radiotherapy Mediated by Small Conjugates and Nanosystems

2019

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“…It is worth highlighting the incipient but growing use of MRI in radiation oncology departments. MRI is used not only for simulations, workflow, and treatment planning, but it is also being incorporated into linear accelerators to guide radiotherapy treatment[ 71 ].…”

Section: Future Directionsmentioning

confidence: 99%

Magnetic resonance imaging for prostate cancer before radical and salvage radiotherapy: What radiation oncologists need to know

Couñago¹,

Sancho²,

Catalá³

et al. 2017

WJCO

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External beam radiotherapy (EBRT) is one of the principal curative treatments for patients with prostate cancer (PCa). Risk group classification is based on prostate-specific antigen (PSA) level, Gleason score, and T-stage. After risk group determination, the treatment volume and dose are defined and androgen deprivation therapy is prescribed, if appropriate. Traditionally, imaging has played only a minor role in T-staging due to the low diagnostic accuracy of conventional imaging strategies such as transrectal ultrasound, computed tomography, and morphologic magnetic resonance imaging (MRI). As a result, a notable percentage of tumours are understaged, leading to inappropriate and imprecise EBRT. The development of multiparametric MRI (mpMRI), an imaging technique that combines morphologic studies with functional diffusion-weighted sequences and dynamic contrast-enhanced imaging, has revolutionized the diagnosis and management of PCa. As a result, mpMRI is now used in staging PCa prior to EBRT, with possible implications for both risk group classification and treatment decision-making for EBRT. mpMRI is also being used in salvage radiotherapy (SRT), the treatment of choice for patients who develop biochemical recurrence after radical prostatectomy. In the clinical context of biochemical relapse, it is essential to accurately determine the site of recurrence - pelvic (local, nodal, or bone) or distant - in order to select the optimal therapeutic management approach. Studies have demonstrated the value of mpMRI in detecting local recurrences - even in patients with low PSA levels (0.3-0.5 ng/mL) - and in diagnosing bone and nodal metastasis. The main objective of this review is to update the role of mpMRI prior to radical EBRT or SRT. We also consider future directions for the use and development of MRI in the field of radiation oncology.

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“…Two of these include: (a) the inability to easily determine the patient's electron density for treatment planning dose calculations and (b) geometric distortions produced on MR images. [8][9][10][11][12] Conventionally, the patient's electron density is indirectly determined through a bi-linear relationship between the linear attenuation data collected from a CT and the material's respectively density. Unlike CT, where images are created from back projections of photons penetrating the body, MR does not use radiation to produce an image and solely relies on small fluctuations of the materials' net magnetic moment.…”

Section: Introductionmentioning

confidence: 99%

“…Despite the innovation and potential benefits of using a MR unit for MRgRT treatments, there are challenges that limit a MR-only RT workflow. Two of these include: 1) the inability to easily determine the patient’s electron density for treatment planning dose calculations and 2) geometric distortions produced on MR images 8–12 . Conventionally, the patient’s electron density is indirectly determined through a bi-linear relationship between the linear attenuation data collected from a CT and the material’s respectively density.…”

Section: Introductionmentioning

confidence: 99%

“…MR images commonly misrepresent actual patient anatomy in space (geometric distortion) due to the inherent configuration and design of a MR unit 13 . Nonlinear gradients and heterogeneities in the static magnetic field primarily contribute to geometric distortions in the image 10,12,13 . Since geometric distortions and electron densities are limited to the inherent differences in the acquisition process between MR and CT, it is critical that current MRgRT modalities rely on both CT and MR for treatment planning and treatment verification/treatment adaptation, respectively.…”

Section: Introductionmentioning

confidence: 99%

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