This study is conducted to assess the influence of various CT imaging parameters and airway obliquity,
such as reconstruction kernel, field of view, slice thickness, and obliquity of airway on automatic
measurement of airway wall thickness with FWHM method and physical phantom. The phantom, consists
of 11 poly-acryl tubes with various inner lumen diameters and thickness, was used in this study. The
measured density of the wall was 150HU. The airspace outside of tube was filled with poly-urethane
foam, whose density was -900HU, which is similar density of emphysema region. CT images, obtained
with MDCT (Sensation 16, Siemens), was reconstructed with various reconstruction kernel (B10f, B30f,
B50f, B70f and B80f), different field of views (180mm, 270mm, 360mm), and different thicknesses (0.75,
1, and 2 mm). The phantom was scanned at various oblique angles (0, 30, 45, 60 degree). Using in-house
airway measurement software, central axis of oblique airway was determined by 3D thinning algorithm
and CT image perpendicular to the axis was reconstructed. The luminal area, outer boundary, and wall
thickness was measured by FWHM method at each image. Actual dimension of each tube and measured
CT values on each CT data set was compared. Sharper reconstruction kernel, thicker image thickness, and
larger oblique angle of airway axis results in decrease of measured wall thickness. There was internal
interaction between imaging parameters and obliquity of airway on the accuracy of measurement. There
was a threshold point of 1-mm wall thickness, below which the measurement failed to represent the
change of real thickness. Even using the smaller FOV, the accuracy was not improved. Usage of standard kernel (B50f) and 0.75mm thickness results in the most accurate measurement results, which is
independent of obliquity of airway. (Mean error: 0 Degree 0.067±0.05mm, 30 Degree 0.076±0.09, 45
Degree 0.074±0.09, 60 Degree 0.091±0.09). In this imaging parameters, there was no significant
difference (paired t-test : p > 0.05) between actual measurement and each oblique angle measurement.
The accuracy of airway wall measurement was strongly influenced by imaging parameters and obliquity
of airway. For the accurate measurement, independent of obliquity, we recommend the CT images
reconstructed with 0.75mm slice thickness and B50f or B30f with sharpening filter.
We developed a PC-based clinical workstation and implemented at Asan Medical Center in Seoul, Korea, Hardwares used were Pentium-II, 8M video memory, 64-128 MB RAM, 19 inch color monitor, and 10/100Mbps network adaptor. One of the unique features of this workstation is management tool for folders reside both in PACS short-term storage unit and local hard disk. Users can copy the entire study or part of the study to local hard disk, removable storages, or CD recorder. Even the images in private folders in PACS short-term storage can be copied to local storage devices. All images are saved as DICOM 3.0 file format with 2:1 lossless compression. We compared the prices of copy films and storage medias considering the possible savings of expensive PACS short- term storage and network traffic. Price savings of copy film is most remarkable in MR exam. Price savings arising from minimal use of short-term unit was 50,000 dollars. It as hard to calculate the price savings arising from the network usage. Off-line PC viewer is a cost-effective way of handling private folder management under the PACS environment.
We compared the detectability of solitary pulmonary nodule (SPN) in chest radiographs displayed on different gray-scale monitor luminance. From the long-term archive of Asan Medical Center PACS 40 normal chest PA images and 40 chest PA images with SPN were fetched into the short-term storage. All Chest PA images were acquired using Fuji FCR 9501 or 9500 HQ and down-sampled from 4k to 2k pixel resolutions, and archived to ODJ with 10:1 compression ratio. Mean diameter of the nodules were 12 mm ranging in size from 8 to 20 mm. Nodules were located within the free lung fields (10 cases), overlapped with rib (13 cases), and overlapped with hilum, heart, or subphrenic areas (17 cases). Gray-scale monitors compared in our study were Image Systems M21P2KHBMAX monitor with 100 fL brightness and M21PMAX monitor with 65 fL brightness. After randomization, eight board-certified radiologists determined the presence or absence of nodules independently using worksheet. All radiologists interpreted the images displayed on low-brightness monitors, then after 10 days interpreted the images displayed on high-brightness monitors. Data were gathered using five rating categories, and ROC analysis was performed. Area under the ROC curve was compared for low and high brightness monitors. Mean area under the ROC curve for low-brightness monitor was 0.8597 and high-brightness monitor was 0.8734. Although high-brightness monitor is slightly superior to low-brightness monitor, there was no statistically significant differences between low-brightness and high- brightness monitors (p equals 0.3). Further studies are required for various other subtle lung diseases, long-term physiological effect.
Real-time consultation between referring physicians or radiologists with an expert is critical for timely and adequate management of problem cases. During consultation, both sides need to (1) synchronously manipulate high resolution digital radiographic images or large volume MR/CT images, (2) perform interpretation interactively, and (3) converse with audio. We present a specific designed teleconsultation system with bi-directional remote control technology to meet critical teleconsultation application with high resolution and large volume medical images in a limited bandwidth network environment. We give the system design and implementation methods, and also describe the teleconsultation procedure and protocol used in this system. Finally, preliminary results are discussed.
Proc. SPIE. 3335, Medical Imaging 1998: Image Display
KEYWORDS: Human-machine interfaces, Data modeling, Surgery, Image processing, Medical imaging, Distributed computing, Image display, Computer architecture, Network architectures, Picture Archiving and Communication System
Picture Archiving and Communication Systems (PACS) will evolve into more network-centric, distributed systems in the near future. The reasons for this are better manageability, higher scalability and reduced cost of ownership. Medical image display software should be prepared for this development by making optimized use of networked resources, for instant large medical image files. Most software products currently used, however, is not designed for networked operation and imposes architectural limitations on the possible performance. We will propose an alternative software architecture for medical image display systems that can overcome this limitation without affecting the performance of conventional disk based I/O.