Multi‐echo gradient recalled echo imaging of the pelvis for improved depiction of brachytherapy seeds and fiducial markers facilitating radiotherapy planning and treatment of prostatic carcinoma

Schieda, Nicola; Avruch, Leonard; Shabana, Wael; Malone, Shawn

doi:10.1002/jmri.24590

Cited by 26 publications

(35 citation statements)

References 17 publications

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“…Detected calcifications ≥ 2 mm (FWHM) and number of true GFMs in the CT for each patient in the study are shown. Patient 6,20,22, and 30 were excluded from the study due to major imaging artifacts stemming from large amount of rectum gas.…”

Section: Discussionmentioning

confidence: 99%

“…It was concluded that multiple echoes for GRE provided better detection performance than both conventional FSE and single echo GRE. 22 In our study MEGRE was used without echo combination. Previous study states that the presence of air pockets such as rectal gas could obstruct the GFM detection using bTFE.…”

Section: Discussionmentioning

confidence: 99%

“…Both spin echo and gradient echo MRI sequences have been suggested to improve the signal void visibility. [20][21][22][23][24][25][26] Combinations of different MRI sequences has also been suggested. 27,28 The use of more exotic sequences to even enable a positive contrast of the metal has been developed.…”

Section: Introductionmentioning

confidence: 99%

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Registration free automatic identification of gold fiducial markers in MRI target delineation images for prostate radiotherapy

et al. 2017

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Purpose: The superior soft tissue contrast of magnetic resonance imaging (MRI) compared to computed tomography (CT) has urged the integration of MRI and elimination of CT in radiotherapy treatment (RT) for prostate. An intraprostatic gold fiducial marker (GFM) appears hyperintense on CT. On T2-weighted (T2w) MRI target delineation images, the GFM appear as a small signal void similar to calcifications and post biopsy fibrosis. It can therefore be difficult to identify the markers without CT. Detectability of GFMs can be improved using additional MR images, which are manually registered to target delineation images. This task requires manual labor, and is associated with interoperator differences and image registration errors. The aim of this work was to develop and evaluate an automatic method for identification of GFMs directly in the target delineation images without the need for image registration. Methods: T2w images, intended for target delineation, and multiecho gradient echo (MEGRE) images intended for GFM identification, were acquired for prostate cancer patients. Signal voids in the target delineation images were identified as GFM candidates. The GFM appeared as round, symmetric, signal void with increasing area for increasing echo time in the MEGRE images. These image features were exploited for automatic identification of GFMs in a MATLAB model using a patient training dataset (n = 20). The model was validated on an independent patient dataset (n = 40). The distances between the identified GFM in the target delineation images and the GFM in CT images were measured. A human observatory study was conducted to validate the use of MEGRE images. Results: The sensitivity, specificity, and accuracy of the automatic method and the observatory study was 84%, 74%, 81% and 98%, 94%, 97%, respectively. The mean absolute difference in the GFM distances for the automatic method and observatory study was 1.28 AE 1.25 mm and 1.14 AE 1.06 mm, respectively. Conclusions: Multiecho gradient echo images were shown to be a feasible and reliable way to perform GFM identification. For clinical practice, visual inspection of the results from the automatic method is needed at the current stage.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Registration free automatic identification of gold fiducial markers in MRI target delineation images for prostate radiotherapy

et al. 2017

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“…Fiducial markers are used for IGRT to track the prostate and facilitate co-registration of MP-MR data during RT planning. 4,11 Fiducial markers are used to compensate for misregistration between the expected and actual location of the target that occurs owing to both intrafractional and interfractional motion. 4,11 Motion may be related to patient positioning, adjacent bladder and bowel position/capacity, and treatment-related prostate volume changes.…”

Section: Regional Anatomymentioning

confidence: 99%

“…4,11 Fiducial markers are used to compensate for misregistration between the expected and actual location of the target that occurs owing to both intrafractional and interfractional motion. 4,11 Motion may be related to patient positioning, adjacent bladder and bowel position/capacity, and treatment-related prostate volume changes. 7 Markers are typically inserted using a transrectal approach with TRUS guidance.…”

Section: Regional Anatomymentioning

confidence: 99%

Magnetic resonance for radiotherapy management and treatment planning in prostatic carcinoma

Lim

Malone

Avruch

et al. 2015

BJR

Self Cite

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MRI has an important role for radiotherapy (RT) treatment planning in prostate cancer (PCa) providing accurate visualization of the dominant intraprostatic lesion (DIL) and locoregional anatomy, assessment of local staging and depiction of implanted devices. MRI enables the radiation oncologist to optimize RT planning by better defining target tumour volumes (thereby increasing local tumour control), as well as decreasing morbidity (by minimizing the dose to adjacent normal structures). Using MRI, radiation oncologists can define the DIL for delivery of boost doses of RT using a variety of techniques including: stereotactic body radiotherapy, intensity-modulated radiotherapy, proton RT or brachytherapy to improve tumour control. Radiologists require a familiarity with the different RT methods used to treat PCa, as well as an understanding of the advantages and disadvantages of the various MR pulse sequences available for RT planning in order to provide an optimal multidisciplinary RT treatment approach to PCa. Understanding the expected post-RT appearance of the prostate and typical characteristics of local tumour recurrence is also important because MRI is rapidly becoming an integral component for diagnosis, image-guided histological sampling and treatment planning in the setting of biochemical failure after RT or surgery.

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Improving fiducial and prostate capsule visualization for radiotherapy planning usingMRI

Pathmanathan

Schmidt

Brand

et al. 2019

J Applied Clin Med Phys

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Background and purpose Intraprostatic fiducial markers (FM) improve the accuracy of radiotherapy (RT) delivery. Here we assess geometric integrity and contouring consistency using a T2*‐weighted (T2*W) sequence alone, which allows visualization of the FM. Material and methods Ten patients scanned within the Prostate Advances in Comparative Evidence (PACE) trial (NCT01584258) had prostate images acquired with computed tomography (CT) and Magnetic Resonance (MR) Imaging: T2‐weighted (T2W) and T2*W sequences. The prostate was contoured independently on each imaging dataset by three clinicians. Interobserver variability was assessed using comparison indices with Monaco ADMIRE (research version 2.0, Elekta AB) and examined for statistical differences between imaging sets. CT and MR images of two test objects were acquired to assess geometric distortion and accuracy of marker positioning. The first was a linear test object comprising straight tubes in three orthogonal directions, the second was a smaller test object with markers suspended in gel. Results Interobserver variability for prostate contouring was lower for both T2W and T2*W compared to CT, this was statistically significant when comparing CT and T2*W images. All markers are visible in T2*W images with 29/30 correctly identified, only 3/30 are visible in T2W images. Assessment of geometric distortion revealed in‐plane displacements were under 0.375 mm in MRI, and through plane displacements could not be detected. The signal loss in the MR images is symmetric in relation to the true marker position shown in CT images. Conclusion Prostate T2*W images are geometrically accurate, and yield consistent prostate contours. This single sequence can be used to identify FM and for prostate delineation in a mixed MR‐CT workflow.

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Multi‐echo gradient recalled echo imaging of the pelvis for improved depiction of brachytherapy seeds and fiducial markers facilitating radiotherapy planning and treatment of prostatic carcinoma

Abstract: Multi-echo GRE provides better detection of implanted seeds and fiducial markers when compared with both FSE and single-echo GRE potentially improving RT treatment planning for prostate carcinoma.

Cited by 26 publications

References 17 publications

Registration free automatic identification of gold fiducial markers in MRI target delineation images for prostate radiotherapy

Registration free automatic identification of gold fiducial markers in MRI target delineation images for prostate radiotherapy

Magnetic resonance for radiotherapy management and treatment planning in prostatic carcinoma

Improving fiducial and prostate capsule visualization for radiotherapy planning usingMRI

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