Iodine contrast volume reduction in preoperative transcatheter aortic valve implantation computed tomography: Comparison with 64- and 256-multidetector row computed tomography

INTRODUCTION

This study aimed to compare the vascular enhancement and radiation dose in preoperative transcatheter aortic valve implantation (TAVI) computed tomography (CT) with a reduced contrast medium (CM) using volume scans in 256-multidetector row CT (MDCT) with a standard CM using 64-MDCT.

METHODS

This study included 78 patients with preoperative TAVI CT with either 64- or 256-MDCT. The CM was injected at 1.5 mL/kg in the 64-MDCT group and 1.0 mL/kg in the 256-MDCT group. We compared vascular enhancement of the aortic root and access routes, image quality (IQ) scores, and radiation dose in both groups.

RESULTS

Despite the reduced CM (by 33 %) in the 256-MDCT group, the mean vascular enhancement of the right and left subclavian arteries was significantly higher than that in the 64-MDCT group [284 and 267 Hounsfield units (HU) vs. 376 and 359 HU; p < 0.05]; however, no significant differences in the mean vascular enhancement in the ascending aorta, abdominal aorta at the celiac level, and bilateral common femoral arteries were observed between the two groups (p > 0.05 for all). The median IQ scores at the aortic root were higher in the 256-MDCT group than in the 64-MDCT group (3 vs. 4; p < 0.05), and those at the femoral access routes were comparable (4 vs. 4; p = 0.33). The mean effective dose was significantly reduced by 30 % in the 256-MDCT group (23.6 vs. 16.3 mSv; p < 0.05).

CONCLUSION

In preoperative TAVI CT, volume scans using 256-MDCT provide comparable or better vascular enhancement and IQ with a 30 % reduction in CM and radiation dose than those using 64-MDCT.

IMPLICATIONS FOR PRACTICE

Volume scan using 256-MDCT for preoperative TAVI CT may reduce CM and radiation dose in TAVI patients with renal dysfunction.

Rapid imaging and detection of circulating tumor cells using a wide-field fluorescence imaging system

Circulating tumor cells (CTCs) provide potentially accessible in vivo sources of metastatic cancer cells. As such, considerable focus has been placed on analyzing the genetics of single-CTCs. Prior to these analyses, however, CTCs must first be detected within the blood samples of cancer patients. Current methods for detection of CTCs by fluorescence microscopy require the analysis of hundreds of images per blood sample, making this a time-consuming process that creates a bottleneck in CTC analysis. In this study, we therefore developed a wide-field fluorescence imaging system for rapid CTC detection. For these analyses, CTCs were first isolated using the microcavity array (MCA), a micro-sized filter for CTC recovery that separates cells based on differences in cell size and deformability. Notably, the proposed imaging system enabled rapid (∼10 s) visualization of all stained cells within the 6 mm × 6 mm MCA field via one-shot imaging. Furthermore, the morphology of the cells in the resulting images accurately reflected that observed by conventional microscopy. In total, isolation and detection of CTCs using the MCA combined with our novel wide-field fluorescence imaging system was achieved within 1 h. Thus, our proposed system will provide rapid CTC detection system.

Development of the automated circulating tumor cell recovery system with microcavity array

Circulating tumor cells (CTCs) are well recognized as useful biomarker for cancer diagnosis and potential target of drug discovery for metastatic cancer. Efficient and precise recovery of extremely low concentrations of CTCs from blood has been required to increase the detection sensitivity. Here, an automated system equipped with a microcavity array (MCA) was demonstrated for highly efficient and reproducible CTC recovery. The use of MCA allows selective recovery of cancer cells from whole blood on the basis of differences in size between tumor and blood cells. Intra- and inter-assays revealed that the automated system achieved high efficiency and reproducibility equal to the assay manually performed by well-trained operator. Under optimized assay workflow, the automated system allows efficient and precise cell recovery for non-small cell lung cancer cells spiked in whole blood. The automated CTC recovery system will contribute to high-throughput analysis in the further clinical studies on large cohort of cancer patients.

Microcavity array system for size-based enrichment of circulating tumor cells from the blood of patients with small-cell lung cancer

In this study, we present a method for efficient enrichment of small-sized circulating tumor cells (CTCs) such as those found in the blood of small-cell lung cancer (SCLC) patients using a microcavity array (MCA) system. To enrich CTCs from whole blood, a microfabricated nickel filter with a rectangular MCA (10(4) cavities/filter) was integrated with a miniaturized device, allowing for the isolation of tumor cells based on differences in size and deformability between tumor and blood cells. The shape and porosity of the MCA were optimized to efficiently capture small tumor cells on the microcavities under low flow resistance conditions, while allowing other blood cells to effectively pass through. Under optimized conditions, approximately 80% of SCLC (NCI-H69 and NCI-H82) cells spiked in 1 mL of whole blood were successfully recovered. In clinical samples, CTCs were detectable in 16 of 16 SCLC patients. In addition, the number of leukocytes captured on the rectangular MCA was significantly lower than that on the circular MCA (p < 0.001), suggesting that the use of the rectangular MCA diminishes a considerable number of carryover leukocytes. Therefore, our system has potential as a tool for the detection of CTCs in small cell-type tumors and detailed molecular analyses of CTCs.

Sensitivity of microcavity array system for circulating tumor cells in lung cancer patients

e21007

Background: Epithelial Cell Adhesion Molecule (EpCAM)-based enumeration of circulating tumor cells (CTCs) has prognostic value in solid tumors such as advanced breast, colon and prostate cancers. However, poor sensitivity has been reported in non-small cell lung cancer (NSCLC). We have developed a microcavity array (MCA) system integrated with a microfluidic device for recovery and enumeration of CTsC, regardless of EpCAM expression level. This system can isolate tumor cells on the basis of differences in size and deformability between tumor and hematologic cells. Methods: Paired peripheral blood samples were collected from metastatic lung cancer patients. CTCs were enumerated by EpCAM-based immunomagnetic capture (CellSearch, Veridex) and by the MCA system. In the MCA system, trapped cells were stained with Hoechst 33342, FITC-labeled anti-pan cytokeratin antibodies and PE-labeled anti-CD45 antibodies for subsequent imaging analysis. CTCs were defined as cells with round to oval morphology, a visible nucleus, positive staining for pan-cytokeratin and negative staining for CD45. We evaluated the sensitivity of the MCA system for detecting CTCs in lung cancer patients compared with the CellSearch system. Results: Twenty-two metastatic NSCLC patients and 13 small-cell lung cancer (SCLC) patients were enrolled into this study between April 2011 and January 2012. CTCs were detected using the MCA system in 17 of 22 NSCLC patients (count ≥1 per 7.5 ml) compared with 9 of 22 patients using CellSearch (p=0.013). On the other hand, CTCs were detected using MCA in all 13 SCLC patients compared with just 9 of 13 patients using CellSearch (p=0.012). More CTCs from NSCLC patients were detected by the MCA system (median 13, range 0-313 cells/7.5ml) than by the CellSearch system (median 0, range 0-37 cells/7.5ml) demonstrating statistical superiority (p=0.002, Wilcoxon test). Conclusions: Our results suggest that the MCA system is potentially superior to the CellSearch system for detecting CTCs in lung cancer patients and further clinical development should be considered.

Abstract 2370: Development of microcavity array system for size- and deformability-based isolation of circulating tumor cells

Background: EpCAM-based enumeration of circulating tumor cells (CTCs) has prognostic value in solid tumors such as advanced breast, colon and prostate cancers. However, currently poor sensitivity has limited the use of CTCs in other types of cancers including non-small cell lung cancer (NSCLC). We have developed a microcavity array (MCA) system integrated with microfluidic device for recovery and enumeration of CTC regardless of EpCAM expression level, allowing isolation of tumor cells on the basis of differences in the size and deformability between tumor and hematologic cells. Shapes and sizes of the cavity were optimized in order to trap tumor cells while letting blood cells flow through the microcavities during whole blood filtration. Enrichment of CTCs, fixation, permeabilization, staining, and counting process were implemented in a microfluidic assay within one integrated device. In this study, we evaluated the sensitivity of the MCA system in detecting CTCs with a preclinical model using cell lines and conducted a clinical feasibility study in NSCLC patients. Methods: A wide range of cancer cell lines derived from breast (MCF-7, Hs578T), colon (SW620), gastric (AGS, SNU-1) and lung (A549, HCC-827, NCI-H358, NCI-H441, NCI-H1650, NCI-H1975, NCI-H69, NCI-H82) were used for spike-in experiments. Cells were spiked into 1 mL of healthy donor blood and then introduced into the MCA system. Trapped cells were stained with Hoechst 33342, FITC-labeled anti-pan cytokeratin antibody and PE-labeled anti-CD45 antibody for subsequent imaging analysis. CTCs were defined as cells with round to oval morphology, a visible nucleus, positive staining for pan-cytokeratin and negative staining for CD45. For the clinical evaluation, 16 advanced NSCLC patients were enrolled into the study and we conducted a head-to-head comparison study with CellSearch system. Results: We obtained a quite high recovery rate regardless of tumor types ranging from 80 to 99% in the cell line spike-in experiments containing EpCAM-negative cell lines (Hs578T, SNU-1). Most of recovered cells were viable and were able to proliferate even after isolation process, suggesting the potential for further biological and molecular analyses of CTCs. In the clinical part of the study, CTCs were detectable in 12 out of 16 patients (count β1 per 7.5 ml) with our system. More CTCs were detected by MCA system (median 13, range 0-313 cells/7.5ml blood) than by CellSearch system (median 0, range 0-37 cells/7.5ml blood) demonstrating statistical superiority (p=0.0132, Wilcoxon test). It is also noteworthy that among patients who had negative CTC count by CellSearch system, several patients had positive CTC count by MCA system, suggesting better detection of EpCAM-negative CTCs. Conclusion: Our results suggest the potential of our MCA system for detection of CTCs in solid tumors including NSCLC and further clinical development should be considered.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2370. doi:1538-7445.AM2012-2370