Visible Korean Human: Another trial for making serially sectioned images
Jin Seo Park a, Min Suk Chung a, Jin Yong Kim a, and Hyung Seon Park b a
Department of Anatomy, Ajou University School of Medicine, Suwon, Korea, b
Korea Institute of Science and Technology Information, Daejeon, Korea
Abstract
The Visible Korean Human dataset is currently being made (performance period: Mar 2000 - Aug 2005) according to the following steps. The MR and CT images of the Korean cadaver’s entire body are acquired. The cadaver is serially sectioned (interval: 0.2 mm) and inputted into the personal computer to make anatomical images (pixel size: 0.2 mm) without any missing images. And finally, anatomical structures in the anatomical images are segmented. The Visible Korean Human dataset is expected to be more beneficial than the Visible Human Project dataset since it will provide Korean images which will help in diagnosing and treating the patients belonging to the Oriental race. It also has a complete series of MR and CT images which will improve the study of MR and CT images. The anatomical images without any missing images will help to create more accurate and complete 3D images. Furthermore, these anatomical images are created with thin interval and small pixel size will show small anatomical images. The additional segmented images will make 3D images and virtual dissection software easily.
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Keywords: Visible Korean Human, serially sectioned images, MR images, CT images, anatomical images, segmented images, Korean cadaver, 3D images, virtual dissection software
I. INTRODUCTION The Visible Human Project dataset, which was introduced in 1994 (male) and 1995 (female) by the National Library of Medicine, has been used worldwide in the field of medical imaging. It consists of magnetic resonance (MR) images, computed tomography (CT) images, and anatomical images of the human body. After stacking the Visible Human Project dataset, three dimensional (3D) images can be reconstructed, and then the 3D images can be sectioned and rotated at free angles. The 3D images and virtual dissection software have been helpful in medical education. However, there are several problems encountered with the Visible Human Project dataset. First, it is difficult to adapt it to the Oriental race because the shape and size of human organs differ according to the races. Second, it does not include the MR images of the trunk and limbs because only MR images of the head were acquired. Third, it does not include the complete CT images because the upper limbs’ lateral parts were cut off on the images (Fig. 1a). Fourth, it has missing anatomical images between the four blocks because the cadavers were divided into four blocks using a saw before serial sectioning (Fig. 1b-c). Fifth, it does not show the anatomical structures which are smaller than 0.33 mm because the interval of the anatomical images was 1 mm for male and 0.33 mm for female; and pixel size of those was 0.33 mm. Sixth, it does not include the segmented images which are helpful in making 3D images and virtual dissection software [1-5]. The purpose of this study, Visible Korean Human, is to make other serially sectioned images which
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compensate for the problems encountered with the Visible Human Project dataset. The MR and CT images of the Korean cadaver’s entire body are acquired. The cadaver is serially sectioned at 0.2 mm intervals and inputted into the personal computer to make anatomical images without any missing images. Anatomical structures in the anatomical images are segmented. The preliminary experiment of the Visible Korean Human was performed from Mar 2000 to Aug 2001 for preparing equipments and techniques for the main experiment. The main experiment is currently being performed in male from Sep 2001 to Aug 2003, and in female from Sep 2003 to Aug 2005 (Table 1). This paper will explain the methods and results of the preliminary and main experiments that have been performed.
II. METHODS Three donated Korean male cadavers have been used for the preliminary and main experiments. To ensure the adequate cadavers for the experiment, anatomists and diagnostic radiologists judged a lot of donated Korean cadavers. As a result, two Korean male cadavers were selected for the preliminary experiment because their age, body size, and pathological findings were not considered adequate for the main experiment, but could be used for the preliminary experiment. One Korean male cadaver was selected for the main experiment based on his characteristics: he was young (33 years old), he had average body size (1,718 mm, 55 kg) of a Korean male, and there were few pathological findings (leukemia) (Table 1) (Fig. 2). An immobilizing box was made and the cadaver was put into it. The immobilizing box (inner size: 505 mm X 90 mm X 2,060 mm, outer size: 525 mm X 100 mm X 2,080 mm) was made of wood. The outer size of the immobilizing box was the maximum size which could enter the MRI and CT machines. The cadaver, whose -3-
posture was straightened out, was put into the immobilizing box, parallel to the long axis of the immobilizing box (Fig. 2). Symmetry of the cadaver’s head, body, and limbs was verified using a thread attached longitudinally to the immobilizing box. The posture and direction of the cadaver were fixed with immobilizing agent (Mev-Green™). Two rubber tubes containing MR and CT contrast media were attached to the cadaver. The MR contrast medium (Magnevist, Schering™) was diluted at the ratio of 1:500, and the CT contrast medium was diluted at the ratio of 1:10, and both contrast media were mixed at the ratio of 1:1. The contrast media were injected into two rubber tubes (Tygon tube™) using a syringe, and the rubber tubes were attached to the cadaver from head to foot with an instant adhesive (Loctite™). The MR images of the entire body were acquired at 1 mm intervals. The immobilizing box containing the cadaver was placed on the bed of the MRI machine (GE Signa Horizon 1.5 Tesla MRI System, Milwaukee, WS) parallel to the long axis of the bed by marking the laser positioning light on the immobilizing box. Using body coil, horizontal MR images of the entire body were acquired at 1 mm intervals. Forty MR images were acquired at a time, with a total of two acquisitions. Makeshift T1 method was used for making various tissues distinct. The repetition time was fixed at 1,000 ms and echo time was fixed at 8 s for increasing the signal / noise ratio. The interleave method was used for removing interference between images. A freezer was made and the cadaver was frozen in the freezer. A freezer consisting of two compartments (inner size of each compartment: 645 mm X 650 mm X 2,100 mm) was made. The cadaver in the immobilizing box was wrapped with plastic to avoid freeze dry phenomenon during the long period of storage in the freezer.
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The cadaver in the immobilizing box was placed into the freezer at 36 hours after death until it reached a temperature of - 70 °C. The CT images of the entire body were acquired at 1 mm intervals. After the cadaver in the immobilizing box was frozen, the immobilizing box was placed on the bed of the CT machine (GE High Speed Advantage, Milwaukee, WS), parallel to the long axis of the bed marked by the laser positioning light on the immobilizing box too. Horizontal CT images of the entire body were acquired at 1 mm intervals. Standard algorithm was used for making soft tissue distinct. The voltage was 120 kV, and the electric current time was 280 mAs. The MR and CT images were transferred and saved on the personal computer. The MR and CT images were transferred to the personal computer via Digital Imaging Communications in Medicine (DICOM) network, and saved in TIFF format on Piview software (Mediface™). An embedding box was made and alignment rods were inserted into the embedding box. The embedding box (inner size: 570 mm X 410 mm X 2,000 mm, outer size: 640 mm X 430 mm X 2,090 mm) was made of steel (headboard, footboard, and bottomboard) and wood (two sideboards). The outer size of the embedding box was made to fit inside the freezer. Several holes (diameter: 15 mm) for inserting alignment rods were drilled through the headboard and footboard of the embedding box. Four alignment rods made of white polyacetylene (length: 2,090 mm, diameter: 15 mm) were inserted into these holes. The direction of the four alignment rods was maintained, parallel to the long axis of the embedding box (Fig. 3a). The cadaver was put into the embedding box. Embedding agent (3 g gelatin, 0.05 g methylene blue, 100 ml distilled water) was poured into the embedding box until the agent filled about a quarter of the embedding
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box, and frozen to -70 °C in the freezer. After flattening the upper surface of the frozen embedding agent, the cadaver was transferred from the immobilizing box to the embedding box without changing its direction and posture (Fig. 3a). Symmetry of the cadaver’s head, body, and limbs was also maintained using a thread attached longitudinally to the embedding box. The cadaver was embedded and frozen. A small quantity of embedding agent was poured into the embedding box (Fig. 3b) and frozen to -70 °C in the freezer (Fig. 3c). This process was repeated until the embedding agent fully filled the embedding box. These repeated processes were necessary in order to prevent the freezing embedding agent from pressing the cadaver and the alignment rods. And in order to prevent the freezing embedding agent from widening the two sideboards, the upper parts of the two sideboards were connected using four wooden rods (Fig. 3b). A cryomacrotome for serial sectioning of the entire body at 0.2 mm intervals was made. It is not possible to make 0.2 mm thick-sectioned slices of the entire body but it is possible to mill the entire body at 0.2 mm intervals to make sectioned surfaces. So, a regular milling machine was remodeled into the cryomacrotome. The cryomacrotome for milling the entire body was so large (5 m X 4 m X 3 m) that the laboratory wall had to be removed to transport it into the laboratory; and the cryomacrotome was so heavy (15 ton) that the underground columns and thick floor had to be constructed in the laboratory (Fig. 4a). The cryomacrotome for milling at 0.2 mm intervals was so precise that moving error was just 1 ㎛. Two important components of the cryomacrotome were the mill table and the cutting blade. Optimal moving speed of the embedding box placed on the mill table was determined in the preliminary experiment. Around the cutting blade, twenty teeth were mounted (Fig. 4b).
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Optimal rotating speed of the cutting blade as well as optimal quality and angle of the teeth were also determined in the preliminary experiment. The teeth were replaced with new ones regularly in the main experiment. The embedding box was placed on the cryomacrotome and fixed. Due to the weight (1 ton) of the embedding box, a cart was used to transfer it from the freezer to the cryomacrotome (Fig. 3b) and a crane was used to place it on the mill table of the cryomacrotome (Fig. 4a). The embedding box was placed carefully on the proper place of the mill table parallel to the long axis of the mill table, and firmly fixed using several holes and screws. The embedding box was serially sectioned to make sectioned surfaces. The embedding box on the mill table was moved towards the cutting blade at 0.2 mm interval, and then it was moved parallel to the cutting blade at 20.8 mm/s speed. At this time, the cutting blade was rotated at 628 rpm speed, so that the embedding box was milled at 0.2 mm interval to make a sectioned surface (Fig. 4b). These movements of the embedding box and cutting blade were performed repeatedly by a program composed of numerical control language in the control box of the cryomacrotome. After serial sectioning, the cadaver debris and embedding agent debris were collected for burning out. During serial sectioning, the embedding box was prevented from melting. The embedding box was frozen to -70 °C in the freezer before and after a day’s serial sectioning (Fig. 3c). The embedding box was serially sectioned in the cold seasons (air temperature: below 5 °C) with the laboratory windows opened. During a day’s serial sectioning an n-shaped stainless steel box containing dry ice was placed on the upper and side surfaces of the embedding box and a large block of dry ice was sometimes placed on the sectioned surfaces of
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the embedding box. The sectioned surfaces were treated as follows. If an air cavity (greater than 1 mm) of digestive and respiratory tracts appeared on the sectioned surface, the blue embedding agent was poured into the air cavity and frozen. Dense connective tissue protruding from the sectioned surface was cut off manually using a scalpel. Frost on the sectioned surface was removed with ethyl alcohol. The location and direction of a high resolution digital camera, which was connected to the personal computer, were determined and fixed. We used a digital camera (DSC 560 Kodak™, resolution 3,040 X 2,008) with 50 mm micro lens (Canon™) and a polarizing filter (Kenko™) to prevent unnecessary lights reflected on the sectioned surface from entering the digital camera. The digital camera was connected to the personal computer containing IEEE 1394 adapter (HotConnect 8920, Adaptec™), and the digital camera was controlled on the DCSTwain software (Version 5.9.3.1, Kodak™) in the personal computer; for example, photographing was ordered on the DCSTwain software, so that movement of the digital camera never occurred. To supply the digital camera and personal computer with stable voltage, the automatic voltage regulator (Sampoong™) was used. The digital camera was located to photograph 600 mm X 400 mm sized sectioned surface and directed to face the center of the sectioned surface. After determining the location and direction of the digital camera, the digital camera was firmly fixed on the camera supporter (Fig. 5a). After making a dark room, we determined and fixed the location and direction of two strobe heads, which were accompanied by accessories. For making a dark room, black curtains were hung on the laboratory windows, black plates and black cloths were placed around the sectioned surface (Fig. 5a), and the fluorescent lights of the
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laboratory were turned off. The strobe heads (Digital S, Elinchrom™), strobe reflectors (Compact Reflector, Elinchrom™), power pack (Digital 2, Elinchrom™), and automatic voltage regulator were installed as follows. Two strobe reflectors were attached on two strobe heads to prevent strobe lights from dispersing. The power pack was used to supply the strobe heads with constant electric power, and the automatic voltage regulator was used to supply the power pack with a constant voltage. Two strobe heads were located as high as the sectioned surface and directed to face the sectioned surface at 45° angles. The location and direction were adjusted until constant brightness of the strobe light on all areas of the sectioned surface was verified using an incident exposure meter (Auto Meter IV F, Minolta™). After verification, the location and direction of the two strobe heads were fixed. The sectioned surfaces were photographed using the digital camera to make anatomical images, which were transferred and saved on the personal computer. After serial sectioning, every sectioned surface was moved to a constant location. Then, the sectioned surface containing alignment rods, gray scale, and color patch were photographed under constant conditions (F value: 10, shutter speed: 1/250 s, focusing: manual) while two strobe lights were flashed (Fig. 5a). The anatomical image made by photographing the sectioned surface was transferred to the personal computer, and its quality (brightness, color, focus) was verified on the computer monitor. Then the anatomical image was saved in TIFF format on two personal computers before the next serial sectioning. This photographing was performed everytime after serial sectioning. Constant brightness of the anatomical images was verified using the gray scale, and alignment of those images was verified using four alignment rods (Fig. 5b).
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Aligning between MR, CT, and anatomical images was performed as follows. Excessive margins of the MR and CT images, which did not include the body images, were cropped on Photoshop software (version 6.0, Adobe™). Extent of cropping was determined to allow zoomed-in MR and CT images to be aligned with the corresponding anatomical images (Fig. 6). Furthermore, alignment between the MR images and CT images was verified using the rubber tubes containing the MR and CT contrast media.
III. RESULTS The MR, CT, and anatomical images were acquired. Length of the cadaver was 1,718 mm and interval of the MR and CT images was 1 mm, so that 1,718 sets of MR and CT images were acquired. Each cropped image had 505 X 276 resolution, 8 bit (b) gray color, and 769 kB file size. The length of the cadaver was 1,718 mm and the interval of the anatomical images was 0.2 mm, so that 8,590 anatomical images were acquired. Each anatomical image had 3,040 X 2,008 resolution, 24 b color, and 17,890 kB file size (Table 2). The quality of MR and CT images was satisfactory. The Korean cadaver used in the Visible Korean Human was not large, so that the lateral parts of the upper limbs' MR and CT images were not cut off. Boundaries of the brain, muscles, and intestines were distinct in the MR images while those of the other tissues were distinct in the CT images. MR and CT images of the cadaver were better than those of the living person because the cadaver’s organs did not move during acquisition of the MR and CT images unlike the living person's organs. In particular, The CT images were good because the CT images were acquired after sufficient time without having to be concerned about radiation exposure (Fig. 6a-b).
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The quality of sectioned surfaces and anatomical images was satisfactory. The sectioned surfaces were even and parallel to each other, and the interval of serial sectioning was constant. The anatomical images showed the actual brightness and color of the sectioned surfaces; it was confirmed using the gray scale and color patch in the anatomical images (Fig. 5b). The alignment of anatomical images was satisfactory. Alignment of the anatomical images was confirmed using not only the alignment rods and body images in the anatomical images, but also the corresponding MR and CT images (Fig. 5b, 6). In the preliminary experiment, MR, CT, and anatomical images were aquired along with the equipments and techniques for the main experiment. In the main experiment, better MR, CT, and anatomical images are expected, and the segmented images will be made on the basis of the anatomical images.
IV. DISCUSSION The Visible Korean Human dataset for making better 3D images and virtual dissection software should be made as follows. An adequate Korean cadaver should be selected. To achieve this goal, a lot of donated Korean cadavers were judged. As a result, a Korean male cadaver was selected for the main experiment because he was young, he had an average body size of a Korean male, and there were few pathological findings (Table 1) (Fig. 2). Morphological difference according to the races is not so important to the common person, but it is very important to medical doctors. Therefore, the Visible Korean Human dataset will be very helpful in diagnosing
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and treating patients belonging to the Oriental race. Both MR and CT images of the entire body should be acquired because both images are important in clinics. Boundaries of the gray matter, white matter, muscles, and intestines are distinct in the MR images while those of the other tissues are distinct in the CT images (Fig. 6a-b). MR images of the non-frozen cadaver should be acquired because it is not possible to get MR images of the frozen cadaver. It is important to note that MR images should be acquired as quickly as possible because the tissue alteration such as gas increase in the intestine occurs in the non-frozen cadaver. Therefore, in the main experiment, only T1 weighted MR images were acquired, and then the cadaver was frozen at 36 hours after death. In the preliminary experiment, there was no quality difference between CT images of the non-frozen cadaver and those of the frozen cadaver. Therefore, in the main experiment, only CT images of the frozen cadaver were acquired. Fortunately, the Korean cadaver selected in the Visible Korean Human was not as large as the American cadaver selected in the Visible Human Project, so that the upper limbs' lateral parts were not cut off on the MR and CT images. The entire body should be serially sectioned without dividing the cadaver because dividing the cadaver using a saw yields missing anatomical images. To achieve this goal, large and heavy embedding box, freezer, cryomacrotome, cart, and crane were made. Moreover, a large laboratory and hard work were needed. The sectioned surfaces should be even and parallel to each other and the interval of serial sectioning should be constant. To achieve this goal, a precise cryomacrotome with only 1 ㎛ moving error was made. The embedding box was carefully placed on proper place of the mill table of the cryomacrotome, and firmly fixed. The embedding box was moved towards the cutting blade at a constant interval (0.2 mm). Optimal moving speed
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of the embedding box and optimal rotating speed of the cutting blade were determined. Optimal quality and angle of the teeth were also determined, and the teeth were replaced with new ones regularly. The embedding box should not melt during serial sectioning because good sectioned surfaces cannot be acquired with a melting embedding box. To achieve this goal, the embedding box was frozen to -70 °C before and after a day's serial sectioning (Fig. 3c). The embedding box was serially sectioned in the cold seasons with the laboratory windows opened. The dry ice was placed on the embedding box during serial sectioning. The anatomical images should be as same as the actual feature of the sectioned surfaces as possible. To achieve this goal, first, the sectioned surfaces were treated to display the actual feature as follows. The blue embedding agent was poured into the air cavity and frozen. If not, the sectioned surface, which should appear late, appeared early. Dense connective tissue protruding from the sectioned surface was cut off. Frost on the sectioned surface was removed with ethyl alcohol. Second, constant brightness of the anatomical images was maintained as follows. After making a dark room, two strobe lights were flashed on the sectioned surface. Constant brightness of the strobe lights on all areas of the sectioned surfaces was verified using the incident exposure meter. The sectioned surfaces were photographed with constant F value and shutter speed. Constant brightness of the anatomical images was verified using the gray scale. Third, high quality of the anatomical images was maintained as follows. The sectioned surfaces were photographed using a digital camera whose resolution (3,040 X 2,008) was higher than the resolution (2,048 X 1,216) of the digital camera used for the Visible Human Project [4]. Manual focusing was used, and every focus was verified on the computer monitor. The anatomical images were saved in TIFF format which preserves the exact image information in spite of the
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relatively small file size. The MR, CT, and anatomical images should be horizontal in orientation. To achieve this goal, the cadaver was put in the immobilizing box parallel to the long axis of the immobilizing box, and the cadaver's direction was fixed with the immobilizing agent. The immobilizing box was placed on the beds of the MRI and CT machines parallel to the long axes of the beds. The cadaver was transferred from the immobilizing box into the embedding box without its direction changed. The embedding box was placed and firmly fixed on the mill table of the cryomacrotome parallel to the long axis of the mill table. The anatomical, MR, and CT images should be aligned. To achieve this goal, first, the anatomical images were aligned as follows. During photographing, the constant location of the sectioned surfaces and constant location and direction of the digital camera were maintained. And during photographing, no movement of the digital camera did occurred. After photographing, alignment of the anatomical images was verified using four alignment rods and body images in the anatomical images. Second, the MR and CT images were aligned with the corresponding anatomical images as follows. Excessive margins of the MR and CT images were cropped to allow zoomed-in MR and CT images to be aligned with the anatomical images (Fig. 6). A voxel, a unit of the 3D images made by volume rendering method, should be a regular hexahedron. First, in the Visible Korean Human, 1 mm sized voxel can be made of the MR and CT images because both interval and pixel size of the MR and CT images were 1 mm (Table 2). The approximate pixel size (1 mm) was decided by the field of view (480 mm X 480 mm) and resolution (512 X 512) of MR and CT images. Second, 0.2 mm sized voxel can be made of the anatomical images because both interval and pixel size of the anatomical
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images were 0.2 mm (Table 2). The approximate pixel size (0.2 mm) was decided by the size of the sectioned surfaces (600 mm X 400 mm) and resolution (3,040 X 2,008) of the digital camera. The additional segmented images, which were not made in the Visible Human Project, should be made because they are very helpful in making 3D images and virtual dissection software [3]. To achieve this goal, the outlines of skin, muscles, bones, and important organs in the anatomical images will be drawn. This segmentation will be performed by several anatomists using semiautomatic segmentation software. 3D images should be reconstructed in order to verify that the serially sectioned images are satisfactory. In the preliminary experiment, 3D images of the MR and CT images were reconstructed by volume rendering method, and then the 3D images were sectioned and rotated (Fig. 7). The 3D images revealed that alignment and constant brightness of the MR and CT images were satisfactory. In the main experiment, the 3D images will be reconstructed to verify not only the MR and CT images but also the anatomical and segmented images. Now, the main experiment of the Visible Korean Human is being performed (male: Sep 2001 - Aug 2003, female: Sep 2003 - Aug 2005) on the basis of the equipments and techniques prepared in the preliminary experiment (Table 1). The Visible Korean Human dataset is expected to be more helpful than the Visible Human Project dataset as follows. First, the Korean images will help in diagnosing and treating the patients belonging to the Oriental race. Second, the complete MR and CT images of the entire body at 1 mm intervals will improve the study of MR and CT images. Third, the anatomical images without any missing images will help in reconstructing more complete 3D images. Fourth, the anatomical images with thin interval (0.2 mm) and small pixel size (0.2 mm) will help to show small anatomical structures. Fifth, the additional segmented images will
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help to easily create 3D images and virtual dissection software.
V. CONCLUSIONS In this ongoing study, we are trying to make the Visible Korean Human dataset which can compensate for the problems encountered with the Visible Human Project dataset. The Visible Korean Human dataset will be the basis for making better 3D images and virtual dissection software which will be more helpful in medical education. Like the Visible Human Project dataset, the Visible Korean Human dataset will be distributed worldwide free of charge.
ACKNOWLEDGEMENT This work was supported by 2001 grant from "Department of Medical Sciences, The Graduate School, Ajou University".
REFERENCES [1]
M. J. Ackerman, "The Visible Human Project. A resource for education, " Acad. Med., vol. 74, pp. 667670, 1999.
[2]
M. S. Chung and S. Y. Kim, "Three-dimensional image and virtual dissection program of the brain made of Korean cadaver, " Yonsei Med. J., vol. 41, pp. 299-303, 2000.
[3]
A. Pommert, K. H. Hoehne, B. Pflesser, E. Richter, M. Riemer, T. Schiemann, R. Schubert, U. Schumacher, U. Tiede, "Creating a high-resolution spatial-symbolic model of the inner organs based on the
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Visible Human," Med. Image. Anal., vol. 5, pp. 221-228, 2001. [4]
V. M. Spitzer, M. J. Ackerman, A. L. Scherizinger, and D. G. Whitlock, "The Visible Human male. Technical report," J. of Am. Med. Inform. Assoc., vol. 3, pp. 118-130, 1996.
[5]
V. M. Spitzer and D. G. Whitlock, "The Visible Human dataset. The anatomical platform for human simulation," Anat. Rec., vol. 253, pp. 49-57, 1998.
Address for correspondence Min Suk Chung Department of Anatomy, Ajou University School of Medicine, 5 Wonchon-Dong, Paldal-Gu, Suwon, South Korea / 442-749 Tel: 82-31-219-5032 E-mail:
[email protected]
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(a)
(b)
(c)
Fig. 1. Visible Human Project showing (a) incomplete CT images and (b-c) missing anatomical images between the four blocks.
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Fig. 2. Korean male cadaver put into the immobilizing box for the main experiment.
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(a)
(b)
(c)
Fig. 3. (a-b) The cadaver and embedding agent were put into an embedding box. (c) The embedding box was placed inside a freezer.
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(a)
(b)
Fig. 4. (a) Cryomacrotome. (b) Cutting blade and sectioned surface.
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(a)
(b)
Fig. 5. (a) Digital camera photographing sectioned surface. (b) Anatomical image.
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(a)
(b)
(c)
Fig. 6. Corresponding (a) MR, (b) CT, and (c) anatomical image.
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(a)
(b)
(c)
(d)
Fig. 7. Sectioned 3D images made of (a) MR images and (b) CT images. (c-d) Rotated 3D images made of CT images.
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TABLE 1. Cadavers used for the preliminary and main experiments Sex
Age
Length
Weight
Cause of death
Period of experiment
Male (first)
65
1,789 mm
53 kg
Brain tumor
Mar 2000 – Feb 2001
Male (second)
60
1,720 mm
65 kg
Traffic accident
Mar 2001 – Aug 2001
Male (third)
33
1,718 mm
55 kg
Leukemia
Sep 2001 – Aug 2003
Female (to be donated)
Sep 2003 – Aug 2005
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TABLE 2 Features of the MR, CT, anatomical, and segmented images in the main experiment (male) Interval
Number
Resolution
Color
MR images
1.0 mm
1,718
505 X 276
8 b gray
769 kB
1.3 GB
CT images
1.0 mm
1,718
505 X 276
8 b gray
769 kB
1.3 GB
Anatomical images
0.2 mm
8,590
3,040 X 2,008
24 b color
17,890 kB
153.7 GB
Segmented images
0.2 mm
8,590
3,040 X 2,008
8 b color
5,900 kB
50.7 GB
Total
One file size
Total file size
207.0 GB
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