New trend of MRI diagnosis based on the function and metabolism in the central nervous system

The movement of a subject is a major problem in MRI experiments and diagnosis. At first, this review introduces a new technology named the “Propeller Technique” which can improve the motion artifact by changing the data sampling method in the K trajectory. Our experience of a case who underwent measurement by Propeller technique is reported and the effect of this technique is explained. One of the recent hot topics is the appearance of the clinical 3TMR instrument, with its characteristic differences from that at 1.5T. The advantage of 3T is that it facilitates the evaluation of functional and metabolic information using MR spectroscopy (MRS) and functional MRI. The application of proton MRS in clinical cases is shown and the standard method to use proton MRS in a clinical setting is demonstrated. Furthermore, the new techniques, which can measure important metabolites in small amount such as neurotransmitters, was developed using a high signal to noise ratio and frequency resolution, which are advantages of 3T

ガゾウ シンダン ノ シンポ : Xセン カラ ヒカリ マデ

In this review, recent progress of diagnostic imaging was introduced. X-ray was found about 100 years ago and imaging technology was developed rapidly. The imaging speed and the detail expression are still progress on MRI and CT. Recently the functional information can be served in addition to the morphologic data. Furthermore the technology of optical imaging is now available in the clinical setting, which will give us new information about hemodynamic change and function. The development of diagnostic imaging will be moved to functional information and the fusion technique of functional information and morphologic data in the near future

MRI オ モチイタ ノウ キノウ タイシャ ヒョウカ ノ ケントウ ト モンダイテン

Several methods have been introduced in order to evaluate brain function using MRI. One is the blood oxygen level dependent (BOLD) method, which detects oxygen saturation level in a capillary region, and other is the method of flow volume measurement. Each method can detect activated regions in the brain depending on a kind of tasks and give us functional geometric information of activated brain. However, the activated pixels are not detected depending on electric activity of neurons, but the hemodynamic changes using MRI. Then there may be some cases with discrepancy between true activation of neurons and depicted activation areas by MRI. It will be important to consider difference of mechanism to depict activation when the result of functional MRI is interpreted. To evaluate metabolism in the brain, MR spectroscopy (MRS) is useful for both scientific research and clinical diagnosis. But the sensitivity of MRS is relatively lower than radioisotope methods, and our attention should be paid to maintenance of instrument condition and accuracy of the MRS measurement. MRI has huge possibility to detect function and metabolism in the brain noninvasivelly, but it will be important to understand background mechanism of used technique and avoid misinterpretation

Magnetic resonance tractography exhibiting retrograde degeneration of the corticospinal tract in a patient with a unilateral spinal cord tumor

Background: Transection-induced axonal retrograde degeneration, in contrast to Wallerian degeneration, has not been widely recognized in clinical practice. Aims of the Study: To assess a potential of corticospinal tractography for detecting axonal retrograde degeneration. Methods: We assessed the corticospinal tractography of a 74-year-old woman with monoplegia of the lower limb due to a unilateral thoracic spinal cord tumor. Results: The tractography revealed integrity reduction of the corticospinal tract in the cerebra contralateral to the spinal cord tumor. Conclusions: The present report supports that magnetic resonance tractography has the potential for detecting this under-recognized phenomenon

Current status and prospect of cryotherapy

Cryotherapy is the latest minimally invasive treatment classified as non-vascular interventional radiology（IVR）. Fine needles are used for percutaneous puncture of tumors under imaging guidance. Using high-pressure argon gas for freezing, the needle tip is brought to an extremely low temperature（-４０℃）or lower, and the tumor cells are frozen and destroyed. The advantages of this treatment are that the freezing range can be confirmed on imaging during the procedure, and pain is less intense during the treatment. Currently, in Japan, cryotherapy for tumors, such as renal cancer, is being performed in fewer than３０hospitals. Our hospital decided to introduce a cryotherapy device in ２０１６, and preparations for the operation started at the end of ２０１６. In ２０１７, three in-hospital briefings were held, and we also conducted a tour of facilities with installed cryotherapy devices. After this preparation period, the first treatment was performed at the Tokushima Prefecture in March ２０１８. By August ２０１９, cryotherapy had been performed in seven cases of renal cell carcinoma. In all cases, the treatment was completed without serious complications and could be performed during the scheduled hospital stay. At the follow-ups, no residual or recurrent tumors were found after only one treatment. Currently, only small-diameter renal malignancies are covered by insurance. Therefore, the Japanese Society of Interventional Radiology has submitted a request for the expansion of indications for cryotherapy to the Ministry of Health, Labor and Welfare. In the future, expansion of indications is expected for lung, breast, liver, bone, and soft tissue tumors, and we hope to respond flexibly

Improving the availability of mutual exclusion Systems on Incomplete Networks

We model a distributed system by a graph G=(V, E), where V represents the set of processes and E the set of bidirectional communication links between two processes. G may not be complete. A popular (distributed) mutual exclusion algorithm on G uses a coterie C(⊆2v), which is a nonempty set of nonempty subsets of V (called quorums) such that, for any two quorums P, Q ∈ C, 1) P∩Q ≠φ and 2) P￠Q hold. The availability is the probability that the algorithm tolerates process and/or link failures, given the probabilities that a process and a link, respectively, are operational. The availability depends on the coterie used in the algorithm. This paper proposes a method to improve the availability by transforming a given coterie

Nondominated Coteries on Graphs

Let C and D be two distinct coteries under the vertex set V of a graph G = (V, E) that models a distributed system. Coterie C is said to G-dominate D (with respect to G) if the following condition holds: For any connected subgraph H of G thatcontains a quorum in D (as a subset of its vertex set), there exists a connected subgraph H′ of H that contains a quorum in C. Acoterie C on a graph G is said to be G-nondominated (G-ND) (with respect to G) if no coterie D (≠ C) on G G-dominates C.Intuitively, a G-ND coterie consists of irreducible quorums. This paper characterizes G-ND coteries in graph theoretical terms, and presents a procedure for deciding whether or not a givencoterie C is G-ND with respect to a given graph G, based on this characterization. We then improve the time complexity of thedecision procedure, provided that the given coterie C is nondominated in the sense of Garcia-Molina and Barbara. Finally, wecharacterize the class of graphs G on which the majority coterie is G-ND

Coterie Join Operation and Tree Structured k-Coteries

The coterie join operation proposed by Neilsen and Mizuno produces, from a k-coterie and a coterie, a new k-coterie. For the coterie join operation, this paper first shows 1) a necessary and sufficient condition to produce a nondominated k-coterie (more accurately, a nondominated k-semicoterie satisfying Nonintersection Property) and 2) a sufficient condition to produce a k-conterie with higher availability. By recursively applying the coterie join operation in such a way that the above conditions hold, we define nondominated k-coteries, called tree structured k-coteries, the availabilities of which are thus expected to be very high. This paper then proposes a new k-mutual exclusion algorithm that effectively uses a tree structured k-coterie, by extending Agrawal and El Abbadi's tree algoriyhm. The number of messages necessary for k processes obeying the algorithm to simultaneously enter the critical section is approximately bounded by k log (n / k) in the best case, where n is the number of processes in the system

k-coteries for tolerating network 2-Partition

Network partition, which makes it impossible for some pairs of precesses to communicate with each other, is one of the most serious network failures. Although the notion of k-coterie is introduced to design a k-mutual exclusion algorithm robust against network failures, the number of processes allowed to simultaneously access the critical section may fatally decrease once network partition occurs. This paper discusses how to construct a k-coterie such that the k-mutual exclusion algorithm adopting it is robust against network 2-partition. To this end, we introduce the notion of complemental k-coterie, and show that complemental k-coteries meet our purpose. We then give methods for constructing complemental k-coteries, and show a necessary and sufficient condition for a k-coteries to be complemental