Background. Amide proton transfer (APT) imaging is a novel molecular MRI technique to detect endogenous mobile proteins and peptides through chemical exchange saturation transfer. We prospectively assessed the usefulness of APT imaging in predicting the histological grade of adult diffuse gliomas. Methods. Thirty-six consecutive patients with histopathologically proven diffuse glioma (48.1+14.7 y old, 16 males and 20 females) were included in the study. APT MRI was conducted on a 3T clinical scanner and was obtained with 2 s saturation at 25 saturation frequency offsets v ¼ 26 to +6 ppm (step 0.5 ppm). dB 0 maps were acquired separately for a point-by-point dB 0 correction. APT signal intensity (SI) was defined as magnetization transfer asymmetry at 3.5 ppm: magnetization transfer ratio (MTR) asym ¼ (S [23.5 ppm] 2 S [+3.5 ppm])/S 0. Regions of interest were carefully placed by 2 neuroradiologists in solid parts within brain tumors. The APT SI was compared with World Health Organization grade, Ki-67 labeling index (LI), and cell density. Results. The mean APT SI values were 2.1+0.4% in grade II gliomas (n ¼ 8), 3.2+0.9% in grade III gliomas (n ¼ 10), and 4.1+1.0% in grade IV gliomas (n ¼ 18). Significant differences in APT intensity were observed between grades II and III (P , .05) and grades III and IV (P , .05), as well as between grades II and IV (P , .001). There were positive correlations between APT SI and Ki-67 LI (P ¼ .01, R ¼ 0.43) and between APT SI and cell density (P , .05, R ¼ 0.38). The gliomas with microscopic necrosis showed higher APT SI than those without necrosis (P , .001). Conclusions. APT imaging can predict the histopathological grades of adult diffuse gliomas.

.) is a clinically approved X-Ray contrast agent used in the last 30 years for a wide variety of diagnostic applications with a very good clinical acceptance. Iopamidol contains two types of amide functionalities that can be exploited for the generation of chemical exchange saturation transfer effect. The exchange rate of the two amide proton pools is markedly pH-dependent. Thus, a ratiometric method for pH assessment has been set-up based on the comparison of the saturation transfer effects induced by selective irradiation of the two resonances. This ratiometric approach allows to rule out the concentration effect of the contrast agent and provides accurate pH measurements in the 5.5-7.4 range. Upon injection of Iopamidol into healthy mice, it has been possible to acquire pH maps of kidney regions. Furthermore, it has been also shown that the proposed method is able to report about pH-changes induced in control mice fed with acidified or basified water for a period of a week before image acquisition. Magn Reson Med 65:202-211,

A novel temperature-sensitive liposomal MRI contrast agent has been developed, which allows drug carrier localization using (1)H CEST with simultaneous quantification of the drug release using (19)F MR imaging in response to a local temperature increase.

Fluorine MRI offers broad potential for specific detection and quantification of molecularly targeted agents in diagnosis and therapy planning or monitoring. Because non-proton MRI applications lack morphological information, accompanying proton images are needed to elucidate the spatial tissue context. Furthermore, low concentrations typical of targeted molecular imaging agents require long examinations for signal averaging during which physiological motion may lead to blurring, underestimation in signal quantification, and erroneous localization of the agent distribution. Novel methods for truly simultaneous acquisition of dual-nuclei MR data are presented that offer efficient and precise anatomical localization of fluorine signals using accurate motion correction based on contemporaneous proton signals. The feasibility of simultaneous dual-nuclei MRI motion correction and corresponding dual-resolution reconstruction, providing nuclei-specific spatial resolution to retrospectively optimize the balance between signal-to-noise ratio and resolution, is shown on a clinical 3 T MR system. Magn Reson Med 66:1116-1122,

Purpose To evaluate the utility of amide proton transfer (APT) imaging in estimating histologic grades of endometrioid endometrial adenocarcinoma (EEA). Materials and Methods The institutional review board approved this prospective study. Between June 2012 and March 2016, 32 patients with EEA underwent magnetic resonance (MR) imaging. After their surgical procedures, their EEAs were confirmed pathologically and classified into histologic grades: grade 1 (n = 11), grade 2 (n = 11), and grade 3 (n = 10). The APT signal intensities (SIs) and the mean and minimum apparent diffusion coefficients (ADCs) of the three grades were calculated and compared. Spearman rank correlation coefficient was also calculated between the APT SIs and histologic grades, and between the ADCs and histologic grades. Results The Spearman correlation coefficient with histologic grade of the APT SIs, the mean ADC, and the minimum ADC were 0.55 (P = .001), 0.03 (P = .84), and -0.30 (P = .09), respectively. The average APT SIs and the mean and minimum ADCs were 2.2% ± 0.2 (standard deviation), 0.9 × 10 mm/sec ± 0.2, and 0.6 × 10 mm/sec ± 0.1 for grade 1; 3.2% ± 0.3, 0.8 × 10 mm/sec ± 0.1, and 0.5 × 10 mm/sec ± 0.1 for grade 2; and 3.7% ± 0.3, 0.9 × 10 mm/sec ± 0.1, and 0.5 × 10 mm/sec ± 0.1 for grade 3, respectively. The APT SIs of grade 3 EEA were significantly higher than those of grade 1 EEA (P = .01), but other pairwise comparisons did not reveal any significant differences (P = .06-.51). The mean and minimum ADCs showed no significant differences among the three histologic grades (P =.13-.51). Conclusion The APT SI was positively correlated with the histologic grades of EEA. RSNA, 2017 Online supplemental material is available for this article.

The 3D FSE Dixon APT method with intrinsic B correction offers a quantitative performance that is similar to that of established two-dimensional (2D) methods. Magn Reson Med 77:2272-2279, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Breast CEST-Dixon imaging shows potential to differentiate more aggressive from less aggressive cancers. Magn Reson Med 80:895-903, 2018. © 2018 International Society for Magnetic Resonance in Medicine.

• Amide proton transfer (APT) imaging helps in grading non-enhancing gliomas • High-grade gliomas showed higher APT signal than low-grade gliomas • APT imaging showed better diagnostic performance than diffusion- and perfusion-weighted imaging.