| Objective:To assess the diagnostic efficacy of spectral CT in the evaluation of osteoblastic metastases (OBMs) in patients with breast and lung cancer.Methods:In this retrospective study,17patients with lung cancer and22patients with breast cancer were scanned on spectral CT scanner (GE, USA). All of them had both plain and enhanced scans of thorax, abdomen or spine. The final diagnosis of osseous metastases was based on imaging and long-term clinical follow-up. In this study, plain scans (PS), arterial phase (AP) and venous phase (VP) of140kVp-quality check (QC) and mono images with1.25mm slice thickness were evaluated by GSI viewer Mono-MD compare in the GE AW4.5post-processing workstation. Lesions had a diameter of more than1.0cm with a relatively homogeneous density on single-energy CT at140kVp-quality check (QC) and virtual monochromatic spectral (VMS) CT images. Regions of interest (ROI) were placed within all lesions where the bone cortex was avoided by placing the ROI in the central3/4of the lesion. The means of CT140kVpvalues、CTvms values and Iodine(Water) and Water (Iodine) densities of osteogenic metastases were measured.The attenuation (CT value and material densities) of the lesions were measured on all the scans.then calculate the increases in value of140kVp-quality check (QC)CT values、virtual monochromatic (40-140keV) CT values and Iodine(Water)densities and Water(Iodine)densities.The increase in CT value (IV) was calculated as (enhanced CT value of arterial/venous phase-plain scan CT value),they are short for IVA and IVV.The slopes of the spectral curve was calculated as (k=(HU40keV-HU100keV)/60).Independent sample t-test was used to compare the attenuation values of140kVp-quality check (QC)CT values、virtual monochromatic (40～140keV) CT values and Iodine(Water) densities and Water (Iodine) densities on the PS、AP、VP and IVA、IVV(g/L). Receiver operator characteristic (ROC) analysis was performed to compare the area under curve (AUC) for the differentiation of OBMs in patients with breast cancer and lung cancer.Results:1. The monochromatic images (40～140) keV CT values of IVV (40～140) kev had statistical significance (p<0.05).The CT value of PS140Vp、AP140kVp、VP140kVp、 IVA140kVp and IVV140kvp on140kVp have no statistically significant difference (p>0.05). The monochromatic images (40-140) keV CT value of PS(4o～140)keV、AP(40～140) keV、VP (40～140)keV and IVA (40～140) kev have no statistically significant difference (p>0.05).2. The IVVIodine(Water)(14.660±13.988)(g/L)and IW water(Iodine)21.956±36.283)(g/L) of breast cancers’ OBMs are higher than lung cancers’,they are5.233±12.677、0.045±15.719(g/L),they are all showed statistical significance (p<0.05). The OBMs of breast cancer and lung cancer didn’t show any statistically significant difference (p>0.05) on PS、AP、VP and IVAIodine(Water)、IVAwater(Iodine).3. The spectral curves of the osteoblastic bone metastases both showed decreasing attenuation with increasing keV values, but the KIVV of osteoblastic metastases of lung cancers were significantly lower than that of breast cancers’, had statistical significance (p<0.05).4. The AUC of VV110kev is0.794, Sensitivities and Specificities were0.778、0.763.The AUC of IVVIodine(Water)、IVVwater(Idodine) were0.701,0.752, Sensitivities were0.778and0.704, Specificities were0.632,0.789; The AUC of kIVV is0.702, Sensitivities and Specificities were0.778,0.632.Conclusion:1. In the monochromatic images,the IVV(40～140)kev(HU)of lung cancer’s osseous metastases are all lower than breast cancer’s, it can differentiate the osseous metastases from breast cancer and lung cancer.2. In the material decomposition image, the IVVlodine(water)、IVVwater(Iodine)(g/L) of lung cancer’s osseous metastases are lower than breast cancer’s,it can differentiate diagnosis of osteoblastic metastases with breast cancer and lung cancer.3. The IVV4o-140Kev of osteoblastic metastases both breast cancer and lung cancer showed the likely spectral curve of decreasing type, but they have different location and shape. The kIVV of breast cancer’s osteoblastic metastases was higher than that of lung cancer, it can differentiate the osseous metastases from breast cancer and lung cancer. |
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