Nobuyuki Kosaka MD, Presenter: Nothing to Disclose

Tatsuro Tsuchida MD, PhD, Abstract Co-Author: Nothing to Disclose

Hidemasa Uematsu MD, Abstract Co-Author: Nothing to Disclose

Hirohiko Kimura MD, PhD, Abstract Co-Author: Nothing to Disclose

Hidehiko Okazawa MD, PhD, Abstract Co-Author: Nothing to Disclose

Harumi Itoh MD, Abstract Co-Author: Nothing to Disclose

Although radiological features of brain tumors are well established, it remains sometimes difficult to differentiate enhancing brain tumors, including malignant lymphoma, high-grade glioma, and metastatic tumor. We therefore hypothesized that FDG-PET could add useful information for differentiating among these tumors.

We evaluated 34 patients with enhancing brain tumor on MRI. All patients also underwent FDG-PET, revealing 7 malignant lymphomas, 9 high-grade gliomas (WHO grade III: 2; grade IV: 7), and 18 metastatic tumors (adenocarcinoma: n=12, squamous cell carcinomas: n=3, small cell carcinoma: n=2, and transitional cell carcinoma: n=1). For PET image analysis, the regions of interest were placed over the tumor (T), the contralateral cortex (C), and the contralateral white matter (WM). Mean and maximum (max) pixel values were determined in each site. Based on these measurements, we calculated the mean and maximum standardized uptake values (SUVmean and SUVmax), as well as the tumor-to-cortex (Tmean/C and Tmax/C) and the tumor-to-white-matter (Tmean/WM and Tmax/WM) activity ratios and compared them among lesions.

All malignant lymphoma parameters calculated here were significantly higher than those of other tumors (p<0.001). High-grade gliomas showed significantly higher SUVmean and SUVmax than metastatic tumors (p<0.05); the other parameters did not differ between them. SUVmax was the most accurate parameter for distinguishing malignant lymphomas. Using an SUVmax of 15.0 as a threshold for diagnosing malignant lymphoma, the sensitivity, specificity, positive and negative predictive values, and diagnostic accuracy were 100%, 96.3%, 87.5%, 100%, and 97.1%, respectively.

FDG-PET may be useful for differentiating common enhancing malignant brain tumors, especially malignant lymphoma versus high-grade glioma and metastatic tumor.

FDG-PET could add useful information for distinguishing common enhancing malignant brain tumors, and is recommended when it is difficult to narrow a differential diagnosis from MRI alone.

Kosaka, N, Tsuchida, T, Uematsu, H, Kimura, H, Okazawa, H, Itoh, H, F-18 Fluorodeoxyglucose Positron Emission Tomography in Common Enhancing Malignant Brain Tumors.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5003561.html