Amide proton transfer imaging of Alzheimer's disease and Parkinson's disease

Amide proton transfer (APT) magnetic resonance imaging (MRI) is an important molecularimaging technique at the protein level in tissue. Neurodegenerative diseases have a highlikelihood of causing abnormal protein accumulation in the brain, which can be detectedby APT MRI. This article briefly introduces the principles and image processing technologyof APT MRI, and reviews the current state of research on Alzheimer's disease and Parkinson's disease using this technique. Early applications of this approach in these twoneurodegenerative diseases are encouraging, which also suggests continued technicaldevelopment and larger clinical trials to gauge the value of this technique.

Amide Proton Transfer Magnetic Resonance Imaging of Alzheimer＇s Disease at 3.0 Tesla： A Preliminary Study

Background：Amide proton transfer （APT） imaging has recently emerged as an important contrast mechanism for magnetic resonance imaging （MRI） in the field of molecular and cellular imaging.The aim of this study was to evaluate the feasibility of APT imaging to detect cerebral abnormality in patients with Alzheimer＆#39;s disease （AD） at 3.0 Tesla.Methods：Twenty AD patients （9 men and 11 women; age range,67-83 years） and 20 age-matched normal controls （11 men and 9 women; age range,63-82 years） underwent APT and traditional MRI examination on a 3.0 Tesla MRI system.The magnetic resonance ratio asymmetry （MTRasym） values at 3.5 ppm of bilateral hippocampi （Hc）,temporal white matter regions,occipital white matter regions,and cerebral peduncles were measured on oblique axial APT images.MTRasym （3.5 ppm） values of the cerebral structures between AD patients and control subjects were compared with independent samples t-test.Controlling for age,partial correlation analysis was used to investigate the associations between mini-mental state examination （MMSE） and the various MRI measures among AD patients.Results：Compared with normal controls,MTRasym （3.5 ppm） values of bilateral Hc were significantly increased in AD patients （right 1.24% ± 0.21% vs.0.83% ± 0.19%,left 1.18% ± 0.18% vs.0.80%± 0.17%,t =3.039,3.328,P =0.004,0.002,respectively）.MTRasym （3.5 ppm） values of bilateral Hc were significantly negatively correlated with MMSE （right r =-0.559,P =0.013; left r=-0.461,P =0.047）.Conclusions：Increased MTRasym （3.5 ppm） values of bilateral Hc in AD patients and its strong correlations with MMSE suggest that APT imaging could potentially provide imaging biomarkers for the noninvasive molecular diagnosis of AD.

Brain development in children with developmental delay using amide proton transfer-weighted imaging and magnetization transfer imaging

Importance:The process of brain development in children with developmental delay is not well known.Amide proton transfer-weighted(APTw)imaging is a novel molecular magnetic resonance imaging(MRI)technique that can noninvasively detect cytosolic endogenous mobile proteins and peptides involved in the myelination process,and may be useful for providing insights into brain development.Objective:To assess the contribution of amide proton transfer-weighted(APTw)imaging and magnetization transfer(MT)imaging to the evaluation of children with developmental delay(DD).Methods:Fifty-one patients with DD were recruited to this study.The patients were divided into two groups according to the state of myelination assessed on conventional magnetic resonance imaging(MRI).Thirty patients(10 girls,20 boys;age range:1-8 months;median age:4 months)in group A showed delayed myelination on MRI,while 21 patients(3 girls,18 boys;age range:12-36months;median age:25months)in group B showed normal myelination on MRI.Fifty-one age-and sex-matched children with normal developmental quotient(DQ)and normal MRI appearance were recruited as normal controls.Three-slice APTw/MT axial imaging was performed at the level of the centrum semiovale,the basal ganglia and the pons.Quantitative data of the MT ratio(MTR)and APTw were analyzed for multiple brain regions.Independent-samplet-tests were used to compare differences in APTw and MTR signals between the two DD groups and normal controls.Analysis of Covariance was conducted to correct the statistical results.The level of statistical significance was set toP<0.05.Results:For group A,the MTR values were lower in all regions(P=0.004-0.033)compared with the normal controls,while the APTw values were higher in the pons,middle cerebellar peduncle,corpus callosum,frontal white matter,occipital white matter and centrum semiovale(P=0.004-0.040).For Group B,the MTR values were slightly reduced,and the APTw values were slightly increased compared with the normal controls,but the differences were not statistically significant(P>0.05).Interpretation:For DD patients showing signs of delayed myelination on MRI,MTR and APTw imaging can help to diagnose myelination delay by quantifying semi-solid macromolecules and cytosolic endogenous mobile proteins and peptides at a molecular level,providing a new method for comprehensive evaluation of DD.For DD patients with normal myelination on MRI,the clinical values of MTR and APTw imaging remain to be explored.