Assessing Tumor Response to Treatment in Patients with Lung Cancer Using Dynamic Contrast-Enhanced CT

Assessing the effect of scanning parameter on the size and density of pulmonary nodules: a phantom study

BACKGROUND

Lung cancer remains a leading cause of death among cancer patients. Computed tomography (CT) plays a key role in lung cancer screening. Previous studies have not adequately quantified the effect of scanning protocols on the detected tumor size. The aim of this study was to assess the effect of various CT scanning parameters on tumor size and densitometry based on a phantom study and to investigate the optimal energy and mA image quality for screening assessment.

METHODS

We proposed a new model using the LUNGMAN N1 phantom multipurpose anthropomorphic chest phantom (diameters: 8, 10, and 12 mm; CT values: - 100, - 630, and - 800 HU) to evaluate the influence of changes in tube voltage and tube current on the size and density of pulmonary nodules. In the LUNGMAN N1 model, three types of simulated lung nodules representing solid tumors of different sizes were used. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were used to evaluate the image quality of each scanning combination. The consistency between the calculated results based on segmentation from two physicists was evaluated using the interclass correlation coefficient (ICC).

RESULTS

In terms of nodule size, the longest diameters of ground-glass nodules (GGNs) were closest to the ground truth on the images measured at 100 kVp tube voltage, and the longest diameters of solid nodules were closest to the ground truth on the images measured at 80 kVp tube voltage. In respect to density, the CT values of GGNs and solid nodules were closest to the ground truth when measured at 80 kVp and 100 kVp tube voltage, respectively. The overall agreement demonstrates that the measurements were consistent between the two physicists.

CONCLUSIONS

Our proposed model demonstrated that a combination of 80 kVp and 140 mA scans was preferred for measuring the size of the solid nodules, and a combination of 100 kVp and 100 mA scans was preferred for measuring the size of the GGNs when performing lung cancer screening. The CT values at 80 kVp and 100 kVp were preferred for the measurement of GGNs and solid nodules, respectively, which were closest to the true CT values of the nodules. Therefore, the combination of scanning parameters should be selected for different types of nodules to obtain more accurate nodal data.

Dynamic contrast-enhanced ultrasonography (D-CEUS) for the early prediction of bevacizumab efficacy in patients with metastatic colorectal cancer

OBJECTIVES

To investigate early changes in tumour perfusion parameters by dynamic contrast-enhanced ultrasonography (D-CEUS) and to identify any correlation with survival and tumour response in patients with metastatic colorectal cancer (CRC) treated with bevacizumab (B).

METHODS

Thirty-seven patients randomized to either chemotherapy (C) plus B or C alone were considered for this study. D-CEUS was performed at baseline and after the first treatment cycle (day 15). Four D-CEUS perfusion parameters were considered: derived peak intensity (DPI), area under the curve (AUC), slope of wash-in (A) and time to peak intensity (TPI).

RESULTS

In patients treated with C plus B, a ≥22.5 % reduction in DPI, ≥20 % increase in TPI and ≥10 % reduction in AUC were correlated with higher progression-free survival in the C+B arm (p = 0.048, 0.024 and 0.010, respectively) but not in the C arm. None of the evaluated parameter modifications had a correlation with tumour response or overall survival.

CONCLUSIONS

D-CEUS could be useful for detecting and quantifying dynamic changes in tumour vascularity as early as 15 days after the start of B-based therapy. Although these changes may be predictive of progression-free survival, no correlation with response or overall survival was found.

KEY POINTS

• D-CEUS showed early changes in liver metastasis perfusion in colorectal cancer. • A decrease in tumour perfusion was associated with longer progression-free survival. • The decrease in perfusion was not correlated with higher overall survival.

[Quantitative Imaging Assessment of Tumor Response to Chemoradiation in Lung Cancer]

精准医疗的实施要求及时准确地对治疗疗效进行评估，以便于治疗方案的调整和优化，从而进一步提高疗效，改善预后。以定量评估为基础的影像组学以其无创、直观和可重复的特点在临床疗效评估方面具有不可替代的作用。本文将综述定量影像学在肺癌放化疗疗效评估中的应用现状及其相关进展。