P2557A novel tool for light sheet-guided analysis of myocardial injury in murine and human samples

Background

Cardiovascular diseases are the most prominent global health threats. For optimal treatment, myocardial biopsies are an indispensable requirement. Current analysis includes histological and biochemical assays with particular limits. Here we present a first approach utilizing light sheet fluorescence microscopy (LSFM) to visualize the 3D vasculatory architecture in the murine heart after experimental myocardial infarction (MI) and in human cardiac biopsies with simultaneously imaging of various immunological infiltrates for disease investigation.

Methods and results

For murine hearts, cardiac vasculature was stained using CD31-AF790 antibody, where we found distinct spots of negative staining, which correlated in size and localisation with other markers of cardiac damage such as triphenyl tetratzolium chloride (TTC) staining, ejection fraction (EF) reduction and plasma cardiac troponin I levels. Using a Ly6G-AF647 antibody, we were able to visualize neutrophil infiltrates 24 h after MI, which localized at the border of the I/R-injury zone. 5 d after MI we imaged the healing vasculatory network using the CD31 marker as well as infiltrated macrophages using F4/80 staining.

Human cardiac vasculature was stained using CD31-AF790 antibody in a whole-mount staining approach. In short, human samples were fixed in 4% PFA and permeabelized using saponin-based detergents. Antibody staining was conducted at 30 °C in the dark over several days. Immunological infiltrates were visualized using human CD66b, CD16, CD64, CD3 and CD19 antibodies in various, simultaneous approaches. After staining, cardiac samples were dehydrated and cleared using ethyl cinnamate (ECi) for light sheet microscopy. The spatial resolution of cardiac blood vessels was determined by CD31 staining, revealing a highly organized and structured vascular tree. Simultaneous staining for immunological infiltrates showed association with areas of enhanced CD31 staining, displaying activated endothelium at sites of inflammation.

Ly6G events in a murine heart

Conclusion

Light sheet-guided analysis of cardiac samples shows promising results in terms of synchronous vascular and immunological investigation. We highlighted its applicability in identifying specific immune cells based on immune-phenotyping. This novel technique may enable future clinical heart disease investigation with a powerful tool for visualization of 3D cardiac structure and identification of multiple immune cell infiltrates.

Therapy response evaluation of malignant lymphoma in a multicenter study: comparison of manual and semiautomatic measurements in CT

PURPOSE

Comparison of manual one-/bi-dimensional measurements versus semi-automatically derived one-/bi-dimensional and volumetric measurements for therapy response evaluation of malignant lymphoma during CT follow-up examinations in a multicenter setting.

MATERIALS AND METHODS

MSCT data sets of patients with malignant lymphoma were evaluated before (baseline) and after two cycles of chemotherapy (follow-up) at radiological centers of five university hospitals. The long axis diameter (LAD), the short axis diameter (SAD) and the bi-dimensional WHO of 307 target lymph nodes were measured manually and semi-automatically using dedicated software. Lymph node volumetry was performed semi-automatically only. The therapeutic response was evaluated according to lymphoma-adapted RECIST.

RESULTS

Based on a single lymph node, semi-automatically derived multidimensional parameters allowed for significantly more accurate therapy response classification than the manual or the semi-automatic unidimensional parameters. Incorrect classifications were reduced by up to 9.6%. Compared to the manual approach, the influence of the study center on correct therapy classification is significantly less relevant when using semi-automatic measurements.

CONCLUSION

Semi-automatic volumetry and bi-dimensional WHO significantly reduce the number of incorrectly classified lymphoma patients by approximately 9.6% in the multicenter setting in comparison to linear parameters. Semi-automatic quantitative software tools may help to significantly reduce wrong classifications that are associated with the manual assessment approach.

KEY POINTS

► Semi-automatic volumetry and bi-dimensional WHO significantly reduce the number of incorrectly classified lymphoma patients ► Manual lymph node evaluation with uni-dimensional parameters is inferior to semi-automatic analysis in a multicenter setting ► Semi-automatic quantitative software tools should be introduced in clinical study evaluation.

Semi-automated volumetric analysis of artificial lymph nodes in a phantom study

PURPOSE

Quantification of tumour burden in oncology requires accurate and reproducible image evaluation. The current standard is one-dimensional measurement (e.g. RECIST) with inherent disadvantages. Volumetric analysis is discussed as an alternative for therapy monitoring of lung and liver metastases. The aim of this study was to investigate the accuracy of semi-automated volumetric analysis of artificial lymph node metastases in a phantom study.

MATERIALS AND METHODS

Fifty artificial lymph nodes were produced in a size range from 10 to 55mm; some of them enhanced using iodine contrast media. All nodules were placed in an artificial chest phantom (artiCHEST®) within different surrounding tissues. MDCT was performed using different collimations (1-5 mm) at varying reconstruction kernels (B20f, B40f, B60f). Volume and RECIST measurements were performed using Oncology Software (Siemens Healthcare, Forchheim, Germany) and were compared to reference volume and diameter by calculating absolute percentage errors.

RESULTS

The software performance allowed a robust volumetric analysis in a phantom setting. Unsatisfying segmentation results were frequently found for native nodules within surrounding muscle. The absolute percentage error (APE) for volumetric analysis varied between 0.01 and 225%. No significant differences were seen between different reconstruction kernels. The most unsatisfactory segmentation results occurred in higher slice thickness (4 and 5 mm). Contrast enhanced lymph nodes showed better segmentation results by trend.

CONCLUSION

The semi-automated 3D-volumetric analysis software tool allows a reliable and convenient segmentation of artificial lymph nodes in a phantom setting. Lymph nodes adjacent to tissue of similar density cause segmentation problems. For volumetric analysis of lymph node metastases in clinical routine a slice thickness of ≤3mm and a medium soft reconstruction kernel (e.g. B40f for Siemens scan systems) may be a suitable compromise for semi-automated volumetric analysis.

Linear and volume measurements of pulmonary nodules at different CT dose levels - intrascan and interscan analysis

PURPOSE

To compare the interobserver variability of the unidimensional diameter and volume measurements of pulmonary nodules in an intrascan and interscan analysis using semi-automated segmentation software on ultra-low-dose computed tomography (ULD-CT) and standard dose CT (SD-CT) data.

MATERIALS AND METHODS

In 33 patients with pulmonary nodules, two chest multi-slice CT (MSCT) datasets (1 mm slice thickness; 20 % reconstruction overlap) had been consecutively acquired with an ultra-low dose (120 kV, 5 mAs) and standard dose technique (120 kV, 75 mAs). MSCT data was retrospectively analyzed using the segmentation software OncoTREAT (MeVis, Bremen, Germany, version 1.3). The volume of 229 solid pulmonary nodules included in the analysis as well as the largest diameter according to RECIST (Response Evaluation Criteria for Solid Tumors) were measured by two radiologists. Interobserver variability was calculated and SD-CT and ULD-CT data compared in an intrascan and interscan analysis.

RESULTS

The median nodule diameter (n = 229 nodules) was registered with 8.2 mm (range: 2.8 to 43.6 mm, mean: 10.8 mm). The nodule volume ranged between 0.01 and 49.1 ml (median 0.1 ml, mean 1.5 ml). With respect to interobserver variability, the intrascan analysis did not reveal statistically significant differences (p > 0.05) between ULD-CT and SD-CT with broader limits of agreement for relative differences of RECIST measurements (-31.0 % + 27.0 % mean -2.0 % for SD-CT; -27.0 % + 38.6 %, mean 5.8 % for ULD-CT) than for volume measurements (-9.4 %, 8.0 %, mean 0.7 % for SD-CT; -13 %, 13 %, mean 0.0 % for ULD-CT). The interscan analysis showed broadened 95 % confidence intervals for volume measurements (-26.5 % 29.1 % mean 1.3 %, and -25.2 %, 29.6 %, mean 2.2 %) but yielded comparable limits of agreement for RECIST measurements.

CONCLUSION

The variability of nodule volumetry assessed by semi-automated segmentation software as well as nodule size determination by RECIST appears to be independent of the acquisition dose in the CT source dataset. This is particularly important regarding size determination of pulmonary nodules in screening trials using low-dose CT data for follow-up imaging.

Semi-automated volumetric analysis of lymph node metastases in patients with malignant melanoma stage III/IV--a feasibility study

Therapy monitoring in oncological patient care requires accurate and reliable imaging and post-processing methods. RECIST criteria are the current standard, with inherent disadvantages. The aim of this study was to investigate the feasibility of semi-automated volumetric analysis of lymph node metastases in patients with malignant melanoma compared to manual volumetric analysis and RECIST. Multislice CT was performed in 47 patients, covering the chest, abdomen and pelvis. In total, 227 suspicious, enlarged lymph nodes were evaluated retrospectively by two radiologists regarding diameters (RECIST), manually measured volume by placement of ROIs and semi-automated volumetric analysis. Volume (ml), quality of segmentation (++/--) and time effort (s) were evaluated in the study. The semi-automated volumetric analysis software tool was rated acceptable to excellent in 81% of all cases (reader 1) and 79% (reader 2). Median time for the entire segmentation process and necessary corrections was shorter with the semi-automated software than by manual segmentation. Bland-Altman plots showed a significantly lower interobserver variability for semi-automated volumetric than for RECIST measurements. The study demonstrated feasibility of volumetric analysis of lymph node metastases. The software allows a fast and robust segmentation in up to 80% of all cases. Ease of use and time needed are acceptable for application in the clinical routine. Variability and interuser bias were reduced to about one third of the values found for RECIST measurements.