VERDICT‐AMICO: Ultrafast fitting algorithm for non‐invasive prostate microstructure characterization

Bonet‐Carne, Elisenda; Johnston, Edward; Daducci, Alessandro; Jacobs, Joseph G.; Freeman, Alex; Atkinson, David; Hawkes, David J.; Punwani, Shonit; Alexander, Daniel C.; Panagiotaki, Eleftheria

doi:10.1002/nbm.4019

Cited by 25 publications

(42 citation statements)

References 48 publications

(120 reference statements)

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“…It is therefore of interest to compare the accuracy and precision of different methods. The VERDICT approach attempts to map mean cell size in human tumors, but to date has been exclusively used in human prostate cancers . The VERDICT approach is different from IMPULSED in that though VERDICT also uses multiple diffusion times; it uses conventional PGSE sequences with higher b values.…”

Section: Discussionmentioning

confidence: 99%

“…Moreover, an optimization of experimental parameters could maintain the precision while minimizing scan time, such as utilized in our previous work using the Cramér‐Rao lower bound approach for optimizing T 1 and quantitative magnetization transfer protocols . Recent optimization efforts have shortened VERDICT acquisition time from 35 minutes to 12 minutes, suggesting that there is much room to accelerate the acquisition protocol of diffusion MRI‐based methods.…”

Section: Discussionmentioning

confidence: 99%

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Magnetic resonance imaging of mean cell size in human breast tumors

Jiang

et al. 2019

Magnetic Resonance in Med

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Purpose Cell size is a fundamental characteristic of all tissues, and changes in cell size in cancer reflect tumor status and response to treatments, such as apoptosis and cell‐cycle arrest. Unfortunately, cell size can currently be obtained only by pathological evaluation of tumor tissue samples obtained invasively. Previous imaging approaches are limited to preclinical MRI scanners or require relatively long acquisition times that are impractical for clinical imaging. There is a need to develop cell‐size imaging for clinical applications. Methods We propose a clinically feasible IMPULSED (imaging microstructural parameters using limited spectrally edited diffusion) approach that can characterize mean cell sizes in solid tumors. We report the use of a combination of pulse sequences, using different gradient waveforms implemented on clinical MRI scanners and analytical equations based on these waveforms to analyze diffusion‐weighted MRI signals and derive specific microstructural parameters such as cell size. We also describe comprehensive validations of this approach using computer simulations, cell experiments in vitro, and animal experiments in vivo and demonstrate applications in preoperative breast cancer patients. Results With fast acquisitions (~7 minutes), IMPULSED can provide high‐resolution (1.3 mm in‐plane) mapping of mean cell size of human tumors in vivo on clinical 3T MRI scanners. All validations suggest that IMPULSED provides accurate and reliable measurements of mean cell size. Conclusion The proposed IMPULSED method can assess cell‐size variations in tumors of breast cancer patients, which may have the potential to assess early response to neoadjuvant therapy.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Magnetic resonance imaging of mean cell size in human breast tumors

Jiang

et al. 2019

Magnetic Resonance in Med

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“…VERDICT MRI maps (as shown in Fig 2 ) were generated by using the accelerated microstructure imaging via convex optimization, or AMICO, framework, which has previously been described by Bonet-Carne et al ( 9 ). The methods used for and results of extravascular extracellular volume fraction and vascular volume fraction analyses are presented in Appendix E1 (online).…”

Section: Methodsmentioning

confidence: 99%

VERDICT MRI for Prostate Cancer: Intracellular Volume Fraction versus Apparent Diffusion Coefficient

Johnston¹,

Bonet‐Carne²,

Ferizi³

et al. 2019

Radiology

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espite the merits of the apparent diffusion coefficient (ADC), reporting quantitative ADC values is not a routine part of clinical practice. This is partially due to lack of biologic specificity (1). Recently, our group presented the feasibility of Vascular, Extracellular, and Restricted Diffusion for Cytometry in Tumors (VERDICT) MRI as a quantitative microstructural imaging tool for prostate cancer (2). VERDICT combines a diffusion-weighted MRI acquisition with a mathematical model and assigns the diffusion-weighted MRI signal to three principal components: (a) intracellular water, (b) water in the extracellular extravascular space, and (c) water in the microvasculature. Because the fraction of each of these compartments differs between each Gleason grade (3), we hypothesized that

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“…Models were written as dictionaries as in the Accelerated Microstructure Imaging via Convex Optimization (AMICO) framework . Signals were modeled using up to 3 compartments: an intracellular (ic), an extracellular (ec) and a vascular (va) compartment.…”

Section: Methodsmentioning

confidence: 99%

“…Models were written as dictionaries as in the Accelerated Microstructure Imaging via Convex Optimization (AMICO) framework. 43,44 Signals were modeled using up to compartments: an intracellular (ic), an extracellular (ec) and a vascular (va) compartment. The problem of estimating amplitudes (x) of dictionary entries from experimental data d (column vector) can be written as:…”

Section: Tissue Modelsmentioning

confidence: 99%

Insights into tissue microstructure using a double diffusion encoding sequence on a clinical scanner: Validation and application to experimental tumor models

Duchêne

Abarca‐Quinones

Leclercq

et al. 2019

Magnetic Resonance in Med

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To present a double diffusion encoding MRI sequence on a clinical scanner to analyze micro-structure and micro-vasculature of tumors. Methods: The sequence was tested on phantoms, asparaguses, and 2 tumors allografts in a rodent. Results were analyzed using an adapted VERDICT model to estimate microstructural parameters. The technical feasibility of the sequence on a 3T clinical system was assessed on a water phantom. The accuracy of cell size estimation was assessed on asparaguses by comparison with light microscopy. Cell size estimations were also validated when limiting relative angles of diffusion encodings to 0 and 180°. Sensitivities to restricted diffusion and incoherent flow from the vasculature were investigated in experimental tumor models. Values of microstructural parameters in viable and decaying tumor tissue were compared with those obtained from histological analysis. Results: Measurements on the water phantom revealed no significant sequence artifacts and accurate apparent diffusion coefficient values within a 4% relative error. In asparaguses, quartiles and medians of pore size distributions typically deviated less than 6% from light microscopy regardless of whether the full or reduced set of relative angles was used. Signal analyses in tumors showed mixed effects of both blood flow and diffusion restriction. Microstructural parameter estimations in tumors were consistent with histology and allowed clear and histology-proven distinctions between decaying and viable tumor tissue. Conclusions: Double diffusion encoding with clinical gradients and scan times allows characterization of restricted diffusion and micro-circulation flow in tumors. Our estimated microstructural parameters are promising for further investigations in assessing microstructural evolutions in tumors.

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VERDICT‐AMICO: Ultrafast fitting algorithm for non‐invasive prostate microstructure characterization

Cited by 25 publications

References 48 publications

Magnetic resonance imaging of mean cell size in human breast tumors

Magnetic resonance imaging of mean cell size in human breast tumors

VERDICT MRI for Prostate Cancer: Intracellular Volume Fraction versus Apparent Diffusion Coefficient

Insights into tissue microstructure using a double diffusion encoding sequence on a clinical scanner: Validation and application to experimental tumor models

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