Heung Sik Kang

Regional bone changes in deep soft tissue hemangiomas: radiographic and MR features.

Abstractu2002Objective. To evaluate changes in bone adjacent to deep soft tissue hemangiomas of the extremities. nDesign and patients. We retrospectively reviewed the plain films of 115 patients with histologically proven deep soft tissue hemangiomas of the extremities. The length and pattern of the bone changes were analyzed and correlated with the MRI examination (n=55) and surgical findings. nResults. Plain film studies demonstrated reactive bone changes adjacent to the deep soft tissue hemangiomas in 24 (21%) patients and phleboliths in 23 (20%) patients. The results of plain film analysis revealed a wide spectrum of regional bone changes adjacent to the hemangiomas, including periosteal reactions (16%), regional osteopenia (1%), cortical erosion (3%), bony overgrowth (3%), coarsening of the trabeculae (5%), and a combination of the above changes (4%). The length of the reactive changes corresponded approximately to the size of the hemangioma in 70% and was longer than the largest dimension of the hemangioma in 30%. Of the 55 patients studied with MRI, 39 (71%) patients had normal bones and 16 (29%) had bone changes. nConclusion. Deep soft tissue hemangiomas may cause changes in adjacent bones. Familiarity with the pattern of reactive bone changes may help to avoid misdiagnosis.

Sonography of Acute Osteomyelitis in Rabbits with Pathologic Correlation

RATIONALE AND OBJECTIVESnUltrasonography (US) has a potential role in the diagnosis of osteomyelitis. The purpose of this study was to determine the characteristic sonographic features of acute osteomyelitis and correlate them with pathologic findings.nnnMATERIALS AND METHODSnAn experimental model of acute osteomyelitis was produced in the tibiae of 20 rabbits. Daily US and plain radiography were performed for 2 weeks. The authors evaluated periosteal reaction, subperiosteal fluid collection, and soft-tissue changes seen with US. A hypoechoic band and a hyperechoic line lying along the cortex were considered positive signs of subperiosteal fluid collection and periosteal reaction, respectively. The findings of periosteal reaction were compared for US and radiography, and pathologic findings were also correlated.nnnRESULTSnThe most common sonographic finding was a hypoechoic band along the cortex (21 [75%] of 28 tibiae), usually associated with a linear periosteal reaction (20 [71%] of 28). This juxtacortical abnormal echogenicity corresponded to periosteal elevation with loose fibrovascular connective tissue and granulation, associated with subperiosteal abscess formation. The periosteal reactions were detected with US before they were seen on radiographs. The periosteum showed gradual thickening during the disease process. In 50% of infected tibiae, inflammation or abscess formation was observed in the surrounding soft tissue.nnnCONCLUSIONnUS readily demonstrates juxtacortical abnormal echogenicity and soft-tissue infection related to acute osteomyelitis. The abnormal echogenicity correlated well with the pathologic findings of periosteal reaction and subperiosteal abscess.

Visually guided spine biopsy simulator with force feedback

A new surgical simulator is developed for spine needle biopsy, that provides realistic visual and force feedback to a trainee in the PC environment. This system is composed of four parts: a 3D human model, visual feedback tool, force feedback device, and an evaluation section. The 3D human model includes multi-slice XCT images, segmentation results, and force-feedback parameters. A block-based technique is adopted for efficient handling of large amounts of data and for easy control of rendering parameters such as opacity. For visual feedback, we implement a virtual CT console box and a 3D visualization tool providing MIP, MPR, summed voxel projection, and realistic 3D color volume rendering view. The visualization tool is for interactive 3D path planning. A haptic device is used to provide force feedback to the biopsy needle during simulation. The interactive force is generated in a voxel-based manner. After each simulation, the evaluation section provides a performance analysis to the trainee. We implemented the system by attaching a 3DOF PHANToMTM device to a PC with 600MHz Pentium III Dual CPUs and 512Mbyte RAM.

Segmentation by evolution for visualization of the lower extremity of the Visible Man.

Medical image segmentation is the crucial process for three-dimensional (3D) modeling. Many studies have claimed to suggest more accurate ways of segmentation. However, such research seems to have the drawback that it works against the parsimony principle. These methods have to reesegment the regions of interest (ROls) for the already segmented data, without taking advantage of the vast amount of past segmentation results. The present report proposes a “seqrnentatlon by evolution” method. It is an advanced segmentation paradigm that incorporates the existing segmentation results. The “seqrnentation by evolution” paradigm was applied to the color images of the Visible Human data.

Virtual integration of multiple-facility PAC systems with ISDN intranet and Web-based DICOM white board

As increasing number of medical facilities are introducing PACS, the needs to interconnect PAC systems are also increased. Although the primary goal of PACS is to enable distribution of radiologic images electronically within hospital and thus assist patient care more efficiently, inter-networking of multiple facility PAC systems can create additional application area and bring about clinical impact. By inter-networking multiple facility PACS, exams can be automatically routed to the remote radiologist when the local radiologist is not available such as during the off- duty hours and vacations. Physicians and radiologists can also benefit from the inter-networking of PACS by making telesconsultation of special cases with remote subspecialty radiologists which can lead to improved diagnostic accuracy and confidence. In this study, we attempted to develop an inter-networking system among the multi-facility PAC systems which can be used for image data transfer and telesconsultation by establishing the ISDN intranet and developing a Web based DICOM white board.