Silun Wang MD, PhD, Presenter: Nothing to Disclose

Zhibo Wen, Abstract Co-Author: Nothing to Disclose

Jing Gu, Abstract Co-Author: Nothing to Disclose

Ge Zhang, Abstract Co-Author: Nothing to Disclose

Jinyuan Zhou PhD, Abstract Co-Author: Nothing to Disclose

Amide proton transfer (APT) imaging can generate molecular MRI signals that are based on the amide protons of endogenous mobile proteins and peptides. The aim of this study is to investigate APT image features of human brain metastases and compare the results with conventional MRI techniques.

We recruited nine patients (mean age ± SD = 54±16 years) who had histologically confirmed brain metastases, including: seven lung carcinomas (four small cell lung cancer, three adenocarcinomas), one gastric adenocarcinoma, and one breast adenocarcinoma. Patients had no clinical history of previous surgery, chemotherapy, or radiotherapy. MRI was performed on a Philips 3T MRI scanner (Achieva 3.0 T). The APT imaging protocol was: RF saturation power = 3 μT; saturation time = 500 ms; slice thickness = 6 mm; matrix = 128×64; FOV = 240×240 mm2. For quantitative analysis, ROIs were drawn according to Gd-enhanced T1w images, and areas of signal enhancement were defined as the tumor core.

Imaging characteristics of brain metastases: Fig.1 shows the MRI results of a lung adenocarcinoma metastasis for a 58-year-old woman. The APT image clearly identifies the tumor core as hyperintense (red arrow), compared to contralateral brain tissue. The hyperintense tumor core corresponds well to Gd enhancing tumor core (red arrow) as well as hyperintense lesion on T2w MR and heterogeneous lesions on T1w MR. Quantitative analysis of APT signal intensities: There are significantly higher APT signal intensities in the tumor core than in peritumoral edematous regions (p<0.01), and in the ipsilateral and contralateral normal appearing white matter (both p<0.001). Metastases from small cell lung cancer have significantly lower APT signal intensities (2.5% ± 0.4%) than lung adenocarcinoma (3.3%±0.3%, p=0.04) and other adenocarcinomas (3.5%±0.2%, p=0.029).

APT imaging can identify tumor core as well as distinguish between biological features of various brain metastases without contrast injection. Combining APT with standard MRI techniques can potentially improve the diagnostic accuracy of MRI.

APT imaging identifies the brain metastasis tumor core as well as the biological features. APT imaging provides additional diagnostic information to characterize brain metastases non-invasively.

Wang, S, Wen, Z, Gu, J, Zhang, G, Zhou, J, Imaging Human Brain Metastases Using Amide Proton Transfer MRI.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12024645.html