Magnetic susceptibility is an intrinsic physical quantity which describes the relationship between material magnetization and applied external magnetic field. Quantitative susceptibility mapping (QSM) is an MRI technology which can quantify the buck magnetic susceptibility of tissue in vivo. It is particularly effective at elucidating anatomy with paramagnetic or diamagnetic components. QSM technology is a method for solving the ill-pose problem of un-conventional de-convolution of the measured tissue magnetic field with the unit magnetic dipole field to obtain the susceptibility source map. Many multi orientation scan based QSM and clinically acceptable single orientation QSM methods have been proposed to solve this ill-posed problem. In this paper, the QSM concept is introduced and the various QSM methods are systematically categorized and discussed. The aim of this paper is to summarize the current research progress of QSM, popularize the knowledge of QSM and promote the improvements and the rational application of QSM in clinical field.
ObjectiveTo evaluate the effect of the timing of surgery on treating refractory epilepsy caused by cavernomas. Method63 patients with refractory epilepsy caused by intracranial supratentorial cavernomas were retrospectively analyzed on the duration of epilepsy, epileptogenesis sitations, and epileptic seizure types. After resection surgeries of cavernomas, the surgical outcomes were compared between the patients with shorter duration of seizures and the longer ones. ResultThe durations of epilepsy were beteen 3 months and 25 years, median 4.5 years. The temporal epilepsies were 43, frontal 12, parietal 3, occipital 1, cingulate gyrus 1, and multiple lobe 3. The overall ILAE class 1 outcome was 71.4% in 63 patients at 2-year-followup, and ILAE class 1 and 2 outcome was 81.6%. The seizure free rate in the group with epilepsy duration shorter than 5 years was 92.1%, better than the 56.0% in the group with epilepsy duration longer than 5 years. ConclusionOnce the diagnosis of medical refractory epilepsy caused by cavernoma was confirmed, the early surgical operation should be considered seriously.