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As a new type of magnetic resonance imaging method, amide proton transfer (APT) imaging can detect the chemical exchange characteristics of free proprotein, peptide amide proton and water proton by water signal changes, reflecting the changes of protein and pH in tissues. In recent years, clinical research on brain tumors, multiple sclerosis, hepatic encephalopathy and cervical cancer have been carried out. It is a radiation-free and non-invasive new magnetic resonance molecular imaging technology. This study briefly reviews the principle of APT technology and its clinical application, and prospects its application prospects in children's abdominal tumors.
Subject(s)
Child , Humans , Abdomen/pathology , Amides , Magnetic Resonance Imaging , Neoplasms/diagnostic imaging , ProtonsABSTRACT
Objective To investigate the feasibility of chemical exchange saturation transfer (CEST) imaging in the measurement of myocardial creatine (Cr) metabolites in phantom model using 3.0 T MR. Methods Five phantoms were made according to the volume percentage of Cr ranging from 10 to 50 mmol/L with an interval of 10 mmol/L. 3.0 T MR examinations with base protocol sequence,sequence with and without ECG were performed. Signal to noise,CrEST effect and Z spectra were analyzed. Comparison of signal noise ratio (SNR) among the three methods was performed using an analysis of variance. Bivariate correlations were obtained through Pearson analysis. Results Phantom studies demonstrated that different concentrations of Cr exhibited significant CEST effect with the three sequences. The SNR obtained by sequences with and without ECG were both higher than that of base sequence (both P<0.05). Moreover,no significance of SNR was found between sequences with and without ECG (P>0.05). There were positive correlation of MTR between sequences with ECG,sequences without ECG and base protocol sequence (r2= 0.974 and 0.997, both P<0.05). Conclusion Compared with base protocol sequence, the optimized sequence with ECG can acquire higher SNR CrEST images,indicating that myocardial CrEST imaging could be performed in clinical practice.
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Chemical exchange saturation transfer (CEST) is a novel MRI technology developed in recent years. In CEST, the exchangeable hydrogen protons were saturated using a selective RF pulse, and then transferred into free water by chemical exchange. This process leads to a reduction of free pool signal, which can be used to infer the solute pool information and environmental information around the solute. In recent years, CEST technology has developed rapidly, and various CEST contrast agents have been developed with their own characteristics and applications. In this review paper, the principles, measurement of CEST signal, types of CEST agents, and the applications of several commonly used CEST contrast agents in human brain imaging researches were introduced including amide proton transfer imaging CEST (APT-CEST), glutamate CEST (gluCEST) and glucose CEST (glucoCEST).
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<p><b>OBJECTIVE</b>This study aims to explore the clinical applicability and relevance of glycosaminoglycan Chemical Exchange Saturation Transfer (gagCEST) for intervertebral disc.</p><p><b>METHODS</b>25 subjects ranging in age from 24 yrs to 74 yrs were enrolled. gagCEST was acquired using a single-slice TSE sequence on a 3T. Saturation used a continuous rectangular RF pulse with B1=0.8 µT and a fixed duration time=1100 ms. Sagittal image was obtained firstly without saturation pulse, and then saturated images were acquired at 52 offsets ranging from ±0.125 to ±7 parts per million (ppm). MR T2 relaxivity map was acquired at the identical location. Six subjects were scanned twice to assess scan-rescan reproducibility.</p><p><b>RESULTS</b>GagCEST intraclass correlation coefficient (ICC) of six subjects was 0.759 for nucleus pulposus (NP) and 0.508 for annulus fibrosus (AF). Bland-Altman plots showed NP had a mean difference of 0.10% (95% limits of agreement: -3.02% to 3.22%); while that of AF was 0.34% (95% limits of agreement: -2.28% to 2.95%). For the 25 subjects, gag CEST in NP decreased as disc degeneration increased, with a similar trend to T2 relaxivity. Gag CEST of AF showed a better correlation with disc degeneration than T2 relaxivity.</p><p><b>CONCLUSION</b>GagCEST in NP and AF decreased as disc degeneration increased, while gagCEST in AF showed a better correlation than T2 relaxivity.</p>
Subject(s)
Adult , Aged , Female , Humans , Male , Middle Aged , Biomarkers , Case-Control Studies , Glycosaminoglycans , Chemistry , Metabolism , Intervertebral Disc , Chemistry , Metabolism , Intervertebral Disc Degeneration , Diagnosis , Metabolism , Lumbar Vertebrae , Magnetic Resonance Imaging , MethodsABSTRACT
The development of advanced magnetic resonance (MR) imaging techniques for tumors has not only lead to improved diagnostic accuracy, but has also assisted with tumor staging, surgical planning, and postoperative follow-up study. Recently introduced and/or clinically used MR imaging techniques for tumors, including chemical exchange saturation transfer imaging, molecular imaging, magnetic resonance spectroscopy, perfusion, and blood flow suppression techniques, could improve diagnostic accuracy and provide useful information to guide the management of tumors. It is essential to properly obtain and evaluate advanced MR images for tumors, depending on the specific characteristics of each tumor.