Fig 1.
Appearance and geometry of channel direction of the prototype ultra-high-resolution CT scanner.
(A) External appearance of the prototype ultra-high-resolution CT scanner. The bore size was 72 cm in diameter. (B) Image showing the directions of the slices and the channels of the CT detector. (C) Geometry of channel direction of the prototype ultra-high-resolution CT scanner. The maximal field of view was 250 mm and number of the channels was 896. (D) Geometry of channel direction of the conventional high-resolution CT scanner. The maximal field of view was 500 mm and number of the channels was 896. U-HRCT: ultra-high-resolution CT, C-HRCT: conventional high-resolution CT.
Fig 2.
Schematic diagram of a slit phantom.
(A) Bird’s-eye view of the slit phantom. The phantom consists of two rectangular parallelepipeds. A small rectangular parallelepiped with five slits was fixed on a large rectangular parallelepiped. (B) Lateral view of the slit phantom. The gray rectangles on the lateral view of the slit phantom (the side of the phantom as viewed from the gray arrow in Fig 2A) indicate the slits; the space between the slits is the same as the width of the slits. The slit phantom was photographed under a microscope; the black arrow indicates the angle at which the photographs were taken.
Fig 3.
Example of CT images for the observer test.
(A) An example of an ultra-high-resolution CT image with different colored dots and annotations used for the observer test. The X and Y coordinates of each dot are shown in parentheses. The image shows a lepidic-predominant invasive adenocarcinoma with a tumor size of 1.2 x 0.9 x 0.9 cm located in segment 2 of the right upper lobe in a 73-year-old man. The blue dot indicates the edge of a solid nodule. The green dot indicates a cavity. The yellow dot indicates pleural indentation of the interlobar fissure. The white dot indicates a fissure between the right upper lobe and the right lower lobe. The red dot indicates the margin of the pulmonary vessel. The purple dot indicates the edge of a bronchiole. The gray dot indicates an interlobular septum. (B) Ultra-high-resolution CT image in which the dots and annotations are hidden.
Fig 4.
Loupe view of the slit phantoms and the results of CT scan.
(A) Loupe view of the 0.3-mm slit phantom as viewed from above. The scale at the right lower part of the figure shows a distance of 0.5 mm. (B) Ultra high-resolution CT was capable of depicting a 0.3-mm slit. The vertical bar at the right side of the figure indicates a distance of 0.5 mm. (C) Conventional high-resolution CT was incapable of depicting the 0.3-mm slit. The vertical bar at the right side of the figure indicates a distance of 0.5 mm. (D) Loupe view of the 0.12-mm slit phantom as viewed from above. The scale in the right lower part of the figure indicates a distance of 0.5 mm. (E) Ultra high-resolution CT was capable of depicting a 0.12-mm slit. The vertical bar at the right side of the figure indicates a distance of 0.5 mm. (F) Conventional high-resolution CT was incapable of depicting the 0.12-mm slit. The vertical bar at the right side of the figure indicates a distance of 0.5 mm.
Table 1.
Comparison of Scores for U-HRCT and 16-row C-HRCT Findings.
U-HRCT: ultra-high-resolution CT, C-HRCT: conventional high-resolution CT.
Table 2.
Comparison of Scores for U-HRCT and 64-row C-HRCT Findings.
U-HRCT: ultra-high-resolution CT, C-HRCT: conventional high-resolution CT.
Table 3.
Interobserver Agreement for U-HRCT and C-HRCT Finding.
U-HRCT: ultra-high-resolution CT, C-HRCT: conventional high-resolution CT.
Fig 5.
CT-pathologic correlation of an adenocarcinoma in situ.
The patient was a 58-year-old female with adenocarcinoma in situ (size, 18 x 16 mm; pT1aN0M0, stage IA). The part-solid nodule was located in segment 6 of the right lower lobe. (A) Loupe view of the pathology specimen (Scale: 1 cm) (H & E, original magnification x1.25). (B) Multiplanar reconstruction (MPR) image from the ultra-high-resolution CT (U-HRCT) data corresponding to the pathology specimen. (C) MPR image from the conventional high-resolution CT (C-HRCT) data corresponding to the pathology specimen. U-HRCT image (Fig B) clearly depicting the solid component (§) immediately adjacent to the bronchial wall (¶) and low-attenuation areas, indicated by a white arrowhead and a white star, in the GGO component of the part-solid nodule. Collapse of the alveolar spaces (§) in Fig 5A corresponds to the solid component (§) of the part-solid nodule on the U-HRCT and C-HRCT images (Fig 5B and 5C), and the nlarged bronchiole (black arrowhead) and enlarged alveolar air spaces (black stars) in Fig 5A correspond to the low-attenuation areas (white arrowhead and white star) in the GGO component of the part-solid nodule on the U-HRCT and C-HRCT images (Fig 5B and 5C). The lepidic component indicated by the black dots in Fig 5A corresponds to the GGO component (black dot) of the part-solid nodule on the U-HRCT and C-HRCT images (Fig 5B and 5C). (D) Maximum intensity projection (MIP) image (2 cm thick) of the pulmonary vessels obtained from the U-HRCT data. (E) MIP image (4 cm thick) of the pulmonary vessels obtained from the C-HRCT data. Fine pulmonary vessels are depicted on the MIP image reconstructed from the U-HRCT data (black arrows). The size of the fine pulmonary vessels, as indicated by the black arrows (Fig 5D), was 0.2 mm. The black star in each MIP image indicates the part-solid nodule of the adenocarcinoma in situ. (F) 3D curved-MPR image of the pulmonary bronchi from the U-HRCT data. (G) 3D curved-MPR image of the pulmonary bronchi from the C-HRCT data. U-HRCT image (Fig 5F) clearly depicting the part-solid opacity (black arrowhead) immediately adjacent to the bronchial wall (white star) with traction bronchiectasis caused by the collapse of the alveoli in the tumor. A: pulmonary artery. V: pulmonary vein.