Cheng Lu1, Maneesh Dave2, H. Matthew Cohn2, Prateek Prasanna1, Jeffrey Katz2, Rajmohan Paspulati3, Anant Madabhushi1, and Satish Viswanath1
1Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States, 2Digestive Health Institute, University Hospital, Case Western Reserve University, Cleveland, OH, United States, 3Dept of Radiology, University Hospital, Case Western Reserve University, Cleveland, OH, United States
Synopsis
We present initial results of identifying
radiomic features (computer-extracted image features from radiography) from baseline diagnostic Magnetic Resonance Enterography (MRE) scans to discriminate patients who will and will not
respond to initial therapy for Crohn’s Disease. Feature
selection was employed to identify the most discriminatory features, followed
by principal component analysis to identify an optimal combination of these features. In a
cohort of 11 patients, the radiomic feature combination was able to
successfully distinguish between responders and non-responders with only 1
misclassification. Multi-scale oriented gradient (Gabor) features appeared to
best capture subtle inflammation-related imaging characteristics on MRE and
hence most predictive of patient outcome. PURPOSE:
We present initial results of identifying radiomic
features to discriminate between patients who will and will not respond to initial
therapy for Crohn’s Disease, derived from a diagnostic Magnetic Resonance Enterography (MRE) scan. It is reported that up to 40% of Crohn’s patients
may not respond to initial therapy, and may instead suffer from increasing
severity of small bowel inflammation [1]. This suggests an urgent need to better
segregate patients who will most benefit from such therapy during diagnosis. MRE
is a high-resolution, non-invasive imaging modality of choice to evaluate
Crohn’s disease presence and activity in
vivo [2]. However, expert interpretation of MRE remains subjective, causing
scores based on such assessment to be highly variable [3]. Further, the
structural complexity of the small bowel makes expert interpretation difficult.
Radiomic features have been shown to capture subtle imaging features of disease
appearance [4], by quantifying higher order information that may not be
discernible upon visual inspection. Our hypothesis is that such advanced
imaging features can capture information indicative of patient outcome to
treatment, which is not based on disease severity alone.
METHODS:
A cohort of 30
patients were considered in this study, all of whom had been imaged via MRE on a
Siemens scanner, as part of the diagnostic clinical protocol for Crohn’s
Disease. Scans from only 11 patients could be utilized due to either poor
quality imaging, fundamental scanner/protocol differences, or colonic
inflammation (instead of the small bowel). The true fast imaging sequence with
steady precession and fat suppression (TRUFIFS) was used. Annotations of Crohn’s
extent on the TRUFIFS images were obtained from an expert radiologist, based on
standard guidelines [5],
and used as the basis for evaluation of radiomic features. Our radiomic feature analysis comprised the
following steps: (i) bias field correction to remove acquisition-related
intensity variation across the image volume, (ii) radiomic feature extraction of
95 pixel-wise features, comprising 1st and 2nd order
statistics, oriented wavelets (Gabor), and local neighborhood-based texture
energy (Laws) [4], (iii) feature pruning, to retain the top 10 radiomics
features whose distributions showed the most separation between the 2 patient
groups, as quantified by the Bhattacharyya distance [6], and (iv) Principal Component
Analysis to project and visualize patient-wise radiomic features (median, variance,
skewness, and kurtosis over all the pixels within each
annotation) into a 3-dimensional Eigen space.
RESULTS AND DISCUSSION:
Of the 11 patients in our cohort, 5 patients responded
and were stable to initial treatment for Crohn’s while the remaining 6 did not
respond and therapy ultimately had to be escalated in these patients; as determined
via patient reports. The 3D scatter plot
of the 11 patients in PCA-reduced Eigen space (Figure 1) suggests good
separability between the 2 groups, with only 1 misclassification (90.9% accuracy). While
the original MRE images of the 2 patients do not indicate marked visual differences
in appearance, the radiomic feature heatmaps demonstrate markedly different
signatures within manually annotated regions of interest in the small bowel between
patients that did and did not respond to treatment (shown in Figure1-(b), (d)).
The most discriminating radiomic features were found to be multi-scale oriented
Gabor features, which capture a combined response for both inflamed bowel wall
regions and lumen regions within disease ROIs, possibly capturing disease
activity and not severity alone.
CONCLUDING REMARKS
We presented preliminary results of identifying
radiomic features from a baseline MRE scan to segregate patients with Crohn’s
Disease who responded favorably to initial therapy from those who did not
respond and needed an escalation of therapy. Gabor features which attempted to
capture combined multi-scale gradient response of inflamed bowel wall and lumen
were found to be most predictive. This work could potentially pave the way for optimal
patient and therapy management for Crohns disease, as well as possibly reducing
the need for invasive procedures to assess treatment response.
Acknowledgements
No acknowledgement found.References
[1] Lapidus
A, et al. Gastroenterology. 1998;114(6): 1151–1160. [2] Griffin N, et al., Insights Imaging. 2012; 3(3): 251–263. [3] Spilseth BD, et al. In: RSNA. 2013. [4] Viswanath
S et al. Neurocomputing. 2014 Nov; 144(20): 13–23. [5] Mowat C, et al., Gut.
2011 May; 60(5): 571–607. [6] Reyes-Aldasoro, C.C., et al. Pattern Recognition,
2006, Vol. 39, Issue 5, pp. 812–826.