Editorial [Hot Topic: Advanced Imagings of Wallerian Degeneration, Pancreatobiliary System, Uterine Cervical Cancer, Periventricular Leukomalacia, Living Cells as well as MR Contrast Agent and QC of SPECT/CT]

MRI has evolved in the last 30 years as rapid, more precise, and more specific. Diffusion tensor imaging (DTI) uses the anisotropy of water motion within structures such as axons to create imaging contrast, which is then used to depict the orientation and volume of white matter fiber tracts. This technique has been propelled by the fast imaging techniques of echoplanar imaging, better gradients, and software post-processing techniques. Dr. Hubertus Axer reviews early diagnosis and also the quantification of Wallerian degeneration by DTI, which may be a crucial factor influencing the functional loss after brain damage. MRI has achieved a level of maturation that has rendered it the most accurate imaging modality for investigating abdominal diseases. Current state-of-the-art magnetic resonance cholangiopancreatography (MRCP) techniques provide high-resolution images of the native pancreatobiliary ductal system, which is a functional system. Dr. Daniel Boll describes perfusion/diffusion-weighted imaging in combination with secretininduced increase in parenchymal perfusion and also quantification of pancreatic excretory reserve. He also discusses cholecystokinin-induced stimulation of the biliary system for the quantification of gallbladder ejection fraction and also the diagnosis of biliary leakage. MRI has been shown to be superior to CT in the workup of uterine and cervical carcinomas and is a very useful problem solving tool in the characterization of gynecologic tumors. Dr. Jongchul Kim reviews MRI findings of uterine cervical carcinomas with the emphasis on the oblique axial images and also dynamic MRI for the appropriate treatment of the patients. Increasing diagnostic sensitivity and specificity proves to be the challenge for MRI. There are many ways to create contrast in MRI. The properties of the MR contrast agent will determine its binding characteristics to the molecule of interest, its tissue penetration and circulation, and potentially its cellular uptake. Exogenous contrast agents can function in many ways: altering T1 or T2 relaxation, providing a source for magnetization transfer, or offering a new nucleus to detect. The chemistry and physics of these compounds are somewhat complex because of issues like field dependence and water exchange. Dr. Yicheng Ni discusses paramagnetic metalloporphyrins, which have new applications in the evaluation of myocardial infarction, tissue viability, ablation therapy, perfusion MRI, atherosclerotic plaque, stem cell tracking and multi-organ enhancement. These porphyrin and nonporphyrin compounds are necrosis-avid contrast agents, which may be useful for target specific diagnosis and therapy of benign and malignant disorders. Altered neonatal brain white matter structure on B-mode ultrasound images has prognostic implications for certain disorders. Periventricular leukomalacia is a brain disorder of very low birth weight preterm infants. Dr. Ewout Vansteenkiste investigated a data set of 140 cases and identified the pathological group with an accuracy of 92.5%. His method can improve both the prognostic finesse and the guidance of early postnatal treatment. Optical imaging of living cells provides a powerful suite of techniques for non-invasive linking of phenotypic expression at the biochemical level to individual genotypes. Imaging of fluorescent marker distribution within living cells has enabled measurement of many active physiological processes including protein transport, membrane potential, and free ion distributions. These markers in conjuction with optical sectioning techniques such as confocal or multiphoton microscopy allow interrogation of cellular dynamics to diffraction-limited spatial resolution. Dr. Xiaoyin Xu reviews updated development of diffusion optical tomography and microendoscopy and their clinical applications............