Interpreting Change in Quantitative Imaging Biomarkers

Obuchowski, Nancy A.

doi:10.1016/j.acra.2017.09.023

Cited by 20 publications

(16 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It must be noted that the RC was based on the first two treatment fractions and therefore might include some treatment effect. The RC denotes the smallest significant difference between two measurements taken under identical conditions, with 95% confidence (25). While it is useful for the comparison of the precision of our measurements to previously reported studies, it might not be the right metric to denote a significant change in a time series.…”

Section: Discussionmentioning

confidence: 97%

“…To determine which changes in IVIM parameters can be attributed to a treatment effect, the repeatability coefficient (RC) of each IVIM parameter was calculated using RC = 1:96 ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi ffi 2 wVar p , where wVar is the mean within-patient variance (25,26). The wVar was determined for the non-cancerous prostate and tumor based on the measurements from the first and second treatment fraction, assuming a negligible influence of the single 3 Gy dose that was received in between.…”

Section: Statisticsmentioning

confidence: 99%

See 1 more Smart Citation

Daily Intravoxel Incoherent Motion (IVIM) In Prostate Cancer Patients During MR-Guided Radiotherapy—A Multicenter Study

et al. 2021

View full text Add to dashboard Cite

PurposeDaily quantitative MR imaging during radiotherapy of cancer patients has become feasible with MRI systems integrated with linear accelerators (MR-linacs). Quantitative images could be used for treatment response monitoring. With intravoxel incoherent motion (IVIM) MRI, it is possible to acquire perfusion information without the use of contrast agents. In this multicenter study, daily IVIM measurements were performed in prostate cancer patients to identify changes that potentially reflect response to treatment.Materials and MethodsForty-three patients were included, treated with 20 fractions of 3 Gy on a 1.5 T MR-linac. IVIM measurements were performed on each treatment day. The diffusion coefficient (D), perfusion fraction (f), and pseudo-diffusion coefficient (D*) were calculated based on the median signal intensities in the non-cancerous prostate and the tumor. Repeatability coefficients (RCs) were determined based on the first two treatment fractions. Separate linear mixed-effects models were constructed for the three IVIM parameters.ResultsIn total, 726 fractions were analyzed. Pre-treatment average values, measured on the first fraction before irradiation, were 1.46 × 10−3 mm2/s, 0.086, and 28.7 × 10−3 mm2/s in the non-cancerous prostate and 1.19 × 10−3 mm2/s, 0.088, and 28.9 × 10−3 mm2/s in the tumor, for D, f, and D*, respectively. The repeatability coefficients for D, f, and D* in the non-cancerous prostate were 0.09 × 10−3 mm2/s, 0.05, and 15.3 × 10−3 mm2/s. In the tumor, these values were 0.44 × 10−3 mm2/s, 0.16, and 76.4 × 10−3 mm2/s. The mixed effects analysis showed an increase in D of the tumors over the course of treatment, while remaining stable in the non-cancerous prostate. The f and D* increased in both the non-cancerous prostate and tumor.ConclusionsIt is feasible to perform daily IVIM measurements on an MR-linac system. Although the repeatability coefficients were high, changes in IVIM perfusion parameters were measured on a group level, indicating that IVIM has potential for measuring treatment response.

show abstract

Section: Discussionmentioning

confidence: 97%

Section: Statisticsmentioning

confidence: 99%

Daily Intravoxel Incoherent Motion (IVIM) In Prostate Cancer Patients During MR-Guided Radiotherapy—A Multicenter Study

et al. 2021

View full text Add to dashboard Cite

show abstract

“…Studies of the repeatability of MRE measurements assess the agreement of repeated measurements using the same system and analysis 79 . Studies of the reproducibility of MRE measurements assess the agreement of measurements of the same subject across different implementations of MRE, different systems, and different analysts 80 …”

Section: Good Practices For Mre Publicationsmentioning

confidence: 99%

MR elastography: Principles, guidelines, and terminology

Manduca

Bayly

Ehman

et al. 2020

Magnetic Resonance in Med

128

144

View full text Add to dashboard Cite

MANDUCA et Al. per year is increasing rapidly (Figure 1). However, numerous types of acquisitions and processing techniques are in use, and MRE results have been expressed in many different quantities: shear modulus (possibly complex), storage modulus, magnitude of the complex shear modulus, shear stiffness (defined in different ways), wave speed, propagation, loss modulus, attenuation, loss tangent or loss factor, phase angle, damping ratio, attenuation, and penetration rate. This list is not exhaustive and does not include additional quantities related to fitting specific assumed material models or anisotropic materials. This diversity of terminology and absence of standardization can lead to confusion (particularly among clinicians) as to the meaning of certain terms, or how to interpret or compare certain types of MRE results. This paper is written by the MRE Guidelines Committee, a group formalized at the first meeting of the ISMRM MRE Study Group, to attempt to clarify and (to some extent) standardize MRE terminology and practice. Specifically, the purpose of this paper is to (1) explain MRE terminology to those not familiar with it, (2) define "good practices" for practitioners of MRE, and (3) discuss some practices and terms that we believe should be standardized and some that should be discouraged. F I G U R E 2 Schematic stress-strain relationship for soft tissue unloaded and at three different tissue-loading states. Magnetic resonance elastography measures the slope of this curve at a given point, as indicated by the tangent line at ε 3

show abstract

“…Correlation in MTV total between readers for the same scan and between scans for the same reader was evaluated with intraclass correlation coefficients. The repeatability assessment using a relative comparison approach was done as described by Obuchowski ( 16 ). The within-subject coefficient of variation (wCV) is given by …”

Section: Methodsmentioning

confidence: 99%