Abstract
2023
Purpose: MR contrast enhancement imaging was widely used in clinical applications on behalf of its advantages on enhancing the lesion-detection and characterization, especially in neural system and tumor detection. Gadolinium based contrast agent (GBCA) was usually used in clinical trial. 18F-FDG PET has a high sensitivity for the detection of pituitary adenoma. In this study, the effects of CE-MRI (contrast enhancement-MRI) on PET qualification in simultaneous integrated PET/MR scanner was estimated.
Methods: Twenty-three patients with pituitary tumors, examined with 18F-FDG tracer at simultaneous integrated PET/MR system with and without gadolinium-based contrast agent (GBCA) enhancement, were retrospectively included in the study. The uptake ratio of 18F-fluorodeoxyglucose (FDG) in each sub-brain and the lesion region before and after GBCA injection was assessed. The mean uptake ratio of 18F-FDG was calculated from each patient before and after GBCA injection. The SUV of the lesion region was focused and evaluated as well. One sample paired T-test was applied to calculate the statistical difference between them.
Results: The T1, T1 FS, T2, T2 FS and T1+, T1 FS+ images were shown in Fig.1. From the image, the GBCA enhanced images of T1+, T1 FS+ can provide better lesion location, compared T1 and T2, even T1 FS and T2 FS. The tracer uptake in all regions of brain cortex before and after GBCA injection is from -1.36% to 2.07%. The maximum and average SUV of the lesion (Fig.2) and all normal brain sub-region (Fig.3, Table.1) does not have an increase or decrease trend in the study before and after the GBCA injection. In a word, there is no significant statistical difference (p>0.05) between the uptake ratio of 18F-FDG before and after GBCA enhancement in the patients.
Conclusions: The feasibility of application of the GBCA on integrated simultaneous PET/MR was notarized and validated on account that the uptake ratio before and after the GBCA injection has not significant changes (P>0.05). Table.1. Average SUV difference between two periods and p value to show the statistical difference significance.
Fig.1. MR and PET/MR images from a representative patient. Coronal T1 image (A) and enhanced T1 imgae(B), sagital T1 FS image (C) and enhanced T1 FS image (D), T2 propeller image (E), T2 FS Propeller image (F) are shown in the figure. Fused PET/MR (MAC-T1) and Fused enhanced PET/MR (MAC+-T1) are displayed in (G) and (H). The lesion is more clear in the enhanced MR image compared with traditional MR image. In other words, the lesion is not that clear in T1, T2,or even T1 FS, T2 FS images. While in fused MAC-T1 and MAR+-T1, the image quality and lesion recognition is silimar before and after the GBCA injection. Fig.2. Statistical analysis for the SUV of lesion region (pituitary). The average and maximum SUV of the lesion before and after the GBCA injection is calculated and averaged. For comparison, MAX and MAX+, AVG and AVG+ are shown and carried out one-sample paired T-test. P=0.775 and P=0.707 (both significantly >0.05) reveal that there is no differnece between the average and maximum SUV between the two periods. Fig.3. The average uptake ratio before and after the GBCA injection of all sub-brain regions. Like Brodmann principle in segmentation of the brain cortex, the segmented sub-brain regions were left (-L) and right (-R) regions of prefrontal lateral (PL), prefrontal medial (PM), sensory motor (SM), anterior cingulate (AC), posterior cingulate (PC), precuneus (P), parietal superior (PS), parietal inferior (PI), occipital lateral (OL), primary visual (PV), temporal lateral (PL), temporal mesial (TM), and pons (PON). The whole cerebrum (CW) is set as the standard SUV to be compared with the selected regions. The average lines of MAC (blue) and MAC+ (red) almost keep the same trend and reveal not too much difference, and furthermore the statistical analysis (p>0.05) of one sample paired T-test support it.