Adaptive statistical iterative reconstruction (ASIR) affects CT radiomics quantification in primary colorectal cancer

OBJECTIVES

To investigate whether adaptive statistical iterative reconstruction (ASIR), a hybrid iterative CT image reconstruction algorithm, affects radiomics feature quantification in primary colorectal cancer compared to filtered back projection. Additionally, to establish whether radiomics from single-slice analysis undergo greater change than those from multi-slice analysis.

METHODS

Following review board approval, contrast-enhanced CT studies from 32 prospective primary colorectal cancer patients were reconstructed with 20% ASIR level increments, from 0 to 100%. Radiomics analysis was applied to single-slice and multi-slice regions of interest outlining the tumour: 70 features, including statistical (first-, second- and high-order) and fractal radiomics, were generated per dataset. The effect of ASIR was calculated by means of multilevel linear regression.

RESULTS

Twenty-eight CT datasets were suitable for analysis. Incremental ASIR levels determined a significant change (p < 0.001) in most statistical radiomics features, best described by a simple linear relationship. First-order statistical features, including mean, standard deviation, skewness, kurtosis, energy and entropy, underwent a relatively small change in both single-slice and multi-slice analysis (median standardised effect size B = 0.08). Second-order statistical features, including grey-level co-occurrence and difference matrices, underwent a greater change in single-slice analysis (median B = 0.36) than in multi-slice analysis (median B = 0.13). Fractal features underwent a significant change only in single-slice analysis (median B = 0.49).

CONCLUSIONS

Incremental levels of ASIR affect significantly CT radiomics quantification in primary colorectal cancer. Second-order statistical and fractal features derived from single-slice analysis undergo greater change than those from multi-slice analysis.

KEY POINTS

• Incremental levels of ASIR determine a significant change in most statistical (first-, second- and high-order) CT radiomics features measured in primary colorectal cancer, best described by a linear relationship. • First-order statistical features undergo a small change, both from single-slice and multi-slice radiomics analyses. • Most second-order statistical features undergo a greater change in single-slice analysis than in multi-slice analysis. Fractal features are only affected in single-slice analysis.

The impact of MRI sequence on tumour staging and gross tumour volume delineation in squamous cell carcinoma of the anal canal

OBJECTIVES

To compare maximum tumour diameter (MTD) and gross tumour volume (GTV) measurements between T2-weighted (T2-w) and diffusion-weighted (DWI) MRI in squamous cell carcinoma of the anal canal (SCCA) and assess sequence impact on tumour (T) staging. Second, to evaluate interobserver agreement and reader delineation confidence.

METHODS

The staging MRI scans of 45 SCCA patients (25 females) were assessed retrospectively by two independent radiologists (0 and 5 years' experience of anal cancer MRI). MTD and GTV were delineated on both T2-w and high-b-value DWI images and compared between sequences; T staging was derived from MTD. Interobserver agreement was assessed and delineation confidence scored (1 to 5) by each observer.

RESULTS

GTV and MTD were significantly and systematically lower on DWI versus T2-w sequences by 14.80%/9.98% (MTD) and 29.70%/12.25% (GTV) for each reader, respectively, causing T staging discordances in approximately a quarter of cases. Bland-Altman limits of agreement were narrower and intraclass correlation coefficients higher for DWI. Delineation confidence was greater on DWI: 40/42 cases were scored confidently (4 or 5) by each reader, respectively, versus 31/36 cases based on T2-w images.

CONCLUSIONS

Sequence selection affects SCCA measurements and T stage. DWI yields higher interobserver agreement and greater tumour delineation confidence.

KEY POINTS

• MTD and GTV measurements are significantly lower on DWI than on T 2 -w MRI. • Such differences cause T staging discordances in up to a quarter of cases. • DWI results in higher agreement between inexperienced and experienced observers. • DWI offers greater tumour delineation confidence to inexperienced readers.

Atomic Force Microscopy Reveals the Dynamic Morphology of Fenestrations in Live Liver Sinusoidal Endothelial Cells

Here, we report an atomic force microscopy (AFM)-based imaging method for resolving the fine nanostructures (e.g., fenestrations) in the membranes of live primary murine liver sinusoidal endothelial cells (LSECs). From data on topographical and nanomechanical properties of the selected cell areas collected within 1 min, we traced the dynamic rearrangement of the cell actin cytoskeleton connected with the formation or closing of cell fenestrations, both in non-stimulated LSECs as well as in response to cytochalasin B and antimycin A. In conclusion, AFM-based imaging permitted the near real-time measurements of dynamic changes in fenestrations in live LSECs.

Morphology and force probing of primary murine liver sinusoidal endothelial cells

Liver sinusoidal endothelial cells (LSECs) represent unique type of endothelial cells featured by their characteristic morphology, ie, lack of a basement membrane and presence of fenestrations-transmembrane pores acting as a dynamic filter between the vascular space and the liver parenchyma. Delicate structure of LSECs membrane combined with a submicron size of fenestrations hinders their visualization in live cells. In this work, we apply atomic force microscopy contact mode to characterize fenestrations in LSECs. We reveal the structure of fenestrations in live LSECs. Moreover, we show that the high-resolution imaging of fenestrations is possible for the glutaraldehyde-fixed LSECs. Finally, thorough information about the morphology of LSECs including great contrast in visualization of sieve plates and fenestrations is provided using Force Modulation mode. We show also the ability to precisely localize the cell nuclei in fixed LSECs. It can be helpful for more precise description of nanomechanical properties of cell nuclei using atomic force microscopy. Presented methodology combining high-quality imaging of fixed cells with an additional nanomechanical information of both live and fixed LSECs provides a unique approach to study LSECs morphology and nanomechanics that could foster understanding of the role of LSECs in maintaining liver homeostasis.