Clinical evaluation of semi-automatic landmark-based lesion tracking software for CT-scans

FLAIRfusion Processing with Contrast Inversion : Improving Detection and Reading Time of New Cerebral MS Lesions

PURPOSE

To evaluate the performance of an innovative image processing approach for detection of T2-weighted hyperintense multiple sclerosis (MS) lesions.

METHODS

In this study 20 consecutive patients with inflammatory demyelinating lesions were retrospectively evaluated of whom 10 patients featured progressive disease and 10 a stable lesion load. 3 mm transversal FLAIRfusion imaging was processed and archived. Image processing was performed through landmark-based 3D co-registration of the previous and current isotropic FLAIR examination followed by inversion of image contrast. Thereby, the hyperintense signals of the unchanged MS plaques extinguish each other, while newly developed lesions appear bright on FLAIRfusion. Diagnostic performance was evaluated by 4 experienced readers. Consensus reading supplied the reference standard. Sensitivity, specificity, NPV (negative predictive value), PPV (positive predictive value), interreader agreement and reading time were the outcome measures analyzed.

RESULTS

Combined sensitivity was 100% at a specificity of 88.2%, with PPV ranging from 83.3% to 90.1% and NPV at 100%. Reading time was nearly 5‑fold faster than conventional side by side comparison (35.6 s vs. 163.7 s, p < 0.001). Cohen's kappa was excellent (>0.75; p < 0.001) and Cronbach's alpha was 0.994.

CONCLUSION

FLAIRfusion provides reliable detection of newly developed MS lesions along with strong interreader agreement across all levels of expertise in 35 s of reading time.

Semi-automatic cone beam CT segmentation of in vivo pre-clinical subcutaneous tumours provides an efficient non-invasive alternative for tumour volume measurements

OBJECTIVE

To evaluate the feasibility and accuracy of using cone beam CT (CBCT) scans obtained in radiation studies using the small-animal radiation research platform to perform semi-automatic tumour segmentation of pre-clinical tumour volumes.

METHODS

Volume measurements were evaluated for different anatomical tumour sites, the flank, thigh and dorsum of the hind foot, for a variety of tumour cell lines. The estimated tumour volumes from CBCT and manual calliper measurements using different volume equations were compared with the "gold standard", measured by weighing the tumours following euthanasia and tumour resection. The correlation between tumour volumes estimated with the different methods, compared with the gold standard, was estimated by the Spearman's rank correlation coefficient, root-mean-square deviation and the coefficient of determination.

RESULTS

The semi-automatic CBCT volume segmentation performed favourably compared with manual calliper measures for flank tumours ≤2 cm(3) and thigh tumours ≤1 cm(3). For tumours >2 cm(3) or foot tumours, the CBCT method was not able to accurately segment the tumour volumes and manual calliper measures were superior.

CONCLUSION

We demonstrated that tumour volumes of flank and thigh tumours, obtained as a part of radiation studies using image-guided small-animal irradiators, can be estimated more efficiently and accurately using semi-automatic segmentation from CBCT scans.

ADVANCES IN KNOWLEDGE

This is the first study evaluating tumour volume assessment of pre-clinical subcutaneous tumours in different anatomical sites using on-board CBCT imaging. We also compared the accuracy of the CBCT method to manual calliper measures, using various volume calculation equations.