Dong-Keun Kim

Outcomes and prognostic factors of intracranial unruptured vertebrobasilar artery dissection

Objective: We aimed to evaluate the long-term clinical outcomes and prognostic factors of symptomatic intracranial unruptured vertebrobasilar artery dissection (siu-VBD). Methods: A total of 191 patients (M:F = 127:64; median age, 46 years) with siu-VBD were treated between January 2001 and December 2008. Presentations, treatments, outcomes, and prognostic factors were retrospectively analyzed. Results: Clinical manifestations were ischemic symptoms with headache (n = 97) or without headache (n = 13) and headache without ischemic symptoms (n = 81). Forty-six patients (24.1%) underwent endovascular treatment. The remaining 145 patients (75.9%) were medically treated with anticoagulants (n = 49), antiplatelets (n = 48), or analgesics alone (n = 48). Clinical follow-up data were available in 178 patients (102 ischemic and 76 nonischemic) at 15 to 102 months (mean, 46 months). None of the siu-VBD hemorrhaged. All 76 patients without ischemic presentation had favorable outcomes (modified Rankin Scale, 0–1). Of the 102 patients with ischemic presentation, outcomes were favorable in 92 and unfavorable in 10 patients. Four patients died; 3 died of causes unrelated to VBD, and one died as a result of basilar artery (BA) dissection. Old age (odds ratio [OR] 1.099; 95% confidence interval [CI] 1.103–1.204; p = 0.042) and BA involvement (OR 11.886; 95% CI 1.416–99.794; p = 0.023) were independent predictors of unfavorable outcomes in siu-VBD with ischemic presentation. Conclusions: Clinical outcomes for siu-VBD were favorable in all patients without ischemic symptoms and in most patients with ischemic presentation. None of the siu-VBD caused subarachnoid hemorrhage. Old age and BA involvement were independent predictors of unfavorable outcome in siu-VBD with ischemic presentation.

Instant wireless transmission of radiological images using a personal digital assistant phone for emergency teleconsultation

The instant transmission of radiological images may be important for making rapid clinical decisions about emergency patients. We have examined an instant image transfer system based on a personal digital assistant (PDA) phone with a built-in camera. Images displayed on a picture archiving and communication systems (PACS) monitor can be captured by the camera in the PDA phone directly. Images can then be transmitted from an emergency centre to a remote physician via a wireless high-bandwidth network (CDMA 1 × EVDO). We reviewed the radiological lesions in 10 normal and 10 abnormal cases produced by modalities such as computerized tomography (CT), magnetic resonance (MR) and digital angiography. The images were of 24–bit depth and 1144 × 880, 1120 × 840, 1024 × 768, 800 × 600, 640 × 480 and 320 × 240 pixels. Three neurosurgeons found that for satisfactory remote consultation a minimum size of 640 × 480 pixels was required for CT and MR images and 1024 × 768 pixels for angiography images. Although higher resolution produced higher clinical satisfaction, it also required more transmission time. At the limited bandwidth employed, higher resolutions could not be justified.

A mobile telemedicine system for remote consultation in cases of acute stroke

A mobile telemedicine system, capable of transmitting video and audio simultaneously, was designed for consulting acute stroke patients remotely. It could use a wireless local area network (e.g. inside the hospital) or a mobile phone network (e.g. outside the hospital). When initiating a call, the sending unit chose a suitable encoding profile based on the measured data throughput, in order to allocate appropriate bit rates for video and audio transmission. The system was tested using a portable digital assistant (PDA) type phone and smart phone as receiving units. Video and audio recordings were made from five patients (two normal and three stroke patients) and then transmitted at different rates. Subjectively, both video and audio qualities improved as the data throughput increased. The physical findings, including facial droop, arm drift and abnormal speech, were observed remotely by four specialists according to the Cincinnati Pre-hospital Stroke Scale guideline. A comparison between the face-to-face method and the mobile telemedicine method showed that there were no discrepancies at bit rates of more than 400 kbit/s. We conclude that specialists could generally conduct remote consultations for stroke patients either using a public mobile network or a wireless LAN.

Embolisation of indirect carotid-cavernous sinus dural arterio-venous fistulae using the direct superior ophthalmic vein approach

SummaryIndirect carotid-cavernous sinus dural arterio-venous fistulae (cDAVF) can be treated by transarterial and/or transvenous embolisation. This study evaluated patients with cDAVF who underwent transvenous embolisation using the direct superior ophthalmic vein (SOV) approach. Between January 2004 and October 2006, eight cDAVF in seven patients were embolised using direct surgical exposure of the SOV when access to the cDAVF via transarterial or transfemoral venous routes was not feasible. Medical records and imaging studies were retrospectively reviewed. The seven patients consisted of four females and three males from 43 to 65-year-old (mean age, 54.4 years). Six cDAVF lesions were located on the left side and two on the right. All fistulae were successfully embolised and showed clinical improvement. One patient presented after treatment with transient venous congestion on the brain stem, which was relieved by osmotic diuretics and steroids. Direct surgical exposure of the SOV for transvenous embolisation of cDAVF can be effective if the facial vein, inferior petrosal sinus, and internal jugular vein are thrombosed. This approach is easy, safe, and effective when performed by a multidisciplinary team.

Imaging of the Inflammatory Response in Reperfusion Injury after Transient Cerebral Ischemia in Rats : Correlation of Superparamagnetic Iron Oxide-Enhanced Magnetic Resonance Imaging with Histopathology

Background: Acute inflammatory responses have been thought to play a central role in ischemia-reperfusion injury after acute ischemic stroke. Superparamagnetic iron oxide (SPIO) particles have been known to enable in-vivo monitoring of macrophage infiltration by magnetic resonance imaging (MRI) in the experimental ischemic rat brain. Purpose: To determine whether the accumulation of macrophages could be seen in vivo in a reperfusion animal model after focal cerebral ischemia using SPIO-enhanced MRI. Material and Methods: Thirty-four adult male rats were enrolled in this study. SPIO particles were injected into the rats at different time points after 1-hour transient occlusion of the middle cerebral artery, and three-dimensional (3D) T2*-weighted magnetic resonance (MR) images with a gradient-echo sequence were performed 24 hours later. Histochemical iron staining was compared with T2* signal abnormalities. Results: At days 3 and 4 post-reperfusion, focal areas of signal loss indicating local accumulation of SPIO particles appeared in a part of the damaged brain. Areas of signal loss corresponded to local accumulation of iron-laden macrophages in histologic sections, and SPIO-induced signal loss indicated active macrophage transmigration into the reperfused brain. Conclusion: SPIO-enhanced MRI demonstrated through in-vivo monitoring that macrophages participate in reperfusion injury at early stages of injury development. SPIO-enhanced MRI could be a useful tool to examine the inflammatory mechanisms involved in reperfusion brain injury.

Scalable MPLS multicast using label aggregation in Internet broadcasting systems

In previous years, the Internet using a conventional IP mechanism had a lot of problems such as slow packet forwarding, complex routing and inefficient usage of network resources. Multi-Protocol Label Switching (MPLS) is one of the mechanisms that are proposed to solve these problems. In addition, multicast is one of the big issues in the Internet society because it can efficiently support real-time multimedia traffic. Therefore, the next generation Internet will be a system which have an MPLS backbone and can support multicast. An MPLS multicast mechanism is considered under Internet broadcasting systems. Specially, the scalability problem of common problems in MPLS and multicast is solved using label aggregation. In the proposed algorithm, the Label Edge Router (LER) of edge router in MPLS has a new table containing information of each tree node. The table is called the multicast Tree Node Table. Extending the Constraint-based Routed Label Distribution Protocol (CR-LDP), the label allocation is performed by using this table. The scalability problem can be solved using this algorithm because it reduces label consumption. So, the MPLS multicast mechanism can be easily supported in a large Internet backbone network.

A portable dental image viewer using a mobile network to provide a tele-dental service

We tested three imaging devices for suitability in emergency dental situations for telemedicine. The three devices were a special-purpose oral camera, a digital single lens reflex (DSLR) camera, and the built-in camera of a mobile phone. A total of 20 subjects volunteered to take part in the study. We simulated five different conditions which could affect the quality of the image and measured image transmission times across two widely available mobile networks (a CDMA-based 3G network and a Wireless Broadband Network, WiBRO). The DSLR produced the best quality images, although it was a relatively large device and not easy to use. The oral camera failed to give satisfactory images under certain conditions (i.e. without extra lighting, out of focus and head motion). In contrast, the mobile phone based camera was very easy to use and to handle, and it gave good information for initial diagnosis, even at high compression ratios. If the image acquisition conditions are carefully set up, this device might be the best for emergency dental trauma situations.

Clinical and Angiographic Characteristics of Multiple Dural Arteriovenous Shunts

BACKGROUND AND PURPOSE: The pathogenesis and characteristics of multiple DAVSs are not well-known. The purpose of this study was to evaluate the angiographic and clinical characteristics of patients with multiple DAVSs with an emphasis on the pathomechanism. MATERIALS AND METHODS: One hundred seventy-nine patients with DAVS were reviewed. Patients with ≥2 fistulas at anatomically separate sites were included. Multiple DAVSs were categorized into synchronous (simultaneous multiplicity) or metachronous (temporal sequential development of multiplicity) types. The angiographic and clinical characteristics of these lesions were analyzed. RESULTS: Fourteen patients were diagnosed with multiple DAVSs (7.8%; synchronous, n = 7; metachronous, n = 7). Thirteen of the 14 patients showed CVR (93%, Borden type II/III). Multiple DAVSs were frequently associated with dural sinus thrombosis (71.4%, n = 10). Synchronous DAVSs developed in association with an occluded sinus (n = 5). De novo metachronous lesions developed in association with thrombosis of a previously patent dural sinus (n = 3) or reopening of an occluded sinus (n = 2). Multiplicity was associated with aggressive initial symptoms in 64.3% (n = 9). The newly developed lesions in the metachronous types were accompanied by hemorrhage (n = 1), neurologic deficit (n = 1), worsening of the initial benign symptoms (n = 2), and incidental detection (n = 3). The mean time interval between the initial diagnosis and de novo lesion detection was 31.3 ± 29.8 months (range, 12–92 months). CONCLUSIONS: Multiplicity of DAVSs is associated with poor angiographic and clinical prognosis, requiring an aggressive treatment and management strategy. Sinus thrombosis has a prominent role in the pathomechanism of DAVSs.

Comparison of stent retriever and intra‐arterial fibrinolysis in patients with acute ischaemic stroke

Although the stent retriever (SR) has shown a better reperfusion rate and clinical outcome than the older generation mechanical clot retrieval device, it is uncertain whether the SR is superior to intra‐arterial fibrinolysis (IAF).

Evaluation of compressed video-images for emergency telemedicine work with trauma patients

Video-encoders in telemedicine systems need to adjust their coding methods for operation on heterogeneous networks on which bandwidth fluctuates. We evaluated MPEG-4 compressed video-pictures of three trauma patients. We compared the original video-frames with compressed video-frames in terms of the peak signal-to-noise ratio (PSNR). In a qualitative evaluation, three emergency specialists scored the quality of the video-images blind, on a five-point scale (1 =bad to 5=excellent). The PSNR increased as the bit rate increased from 0.2 to 6 Mbit/s. When the bit rate was fixed, in other words at a given network bandwidth, a higher PSNR was obtained at the expense of spatial resolution and frame rate. The video quality was highly affected by the amount of camera shake. Emergency telemedicine systems require a high bit rate, high spatial resolution and a high frame rate to achieve optimum video quality. However, if the bandwidth is limited (i.e. the bit rate is fixed), temporal resolution becomes more important than spatial resolution.