Aquilion precision

Between May and July 2018, 62 temporal bones in 31 consecutive adult patients that underwent temporal bone CT with the SHR mode of QDCT (Aquilion Precision; Canon, Tochigi, Japan) were included. The mean age was 59 years (range, 24–86 years); the numbers of male and female patients were 15 and 16, respectively. Backgrounds of the patients were as follows: otitis media cholesteatoma (n = 8), chronic otitis media (n = 8), hearing loss without any mechanical problems (n = 5), ossicular chain disruption (n = 3), otosclerosis (n = 2), ear fullness without any mechanical problems (n = 2), ossicular malformation (n = 2), and temporal bone fracture (n = 1). The following 3 anatomical micro structures with different contrasts were selected for evaluation: spiral osseous lamina (soft tissue and bone in water), tympanic membrane (soft tissue in air), and singular canal (soft tissue in bone). Twenty-five tympanic membranes in 16 patients were excluded from the analysis because the structures had been surgically modified (number of tympanic membranes = 16) or modified by chronic otitis media or cholesteatoma (n = 9). All cases of spiral osseous laminae and singular canals were included in the analysis.

Data from chest CT performed within 14 days before and after lung perfusion SPECT were used (Aquilion Precision; Canon medical systems, Tokyo, Japan). Patients were scanned in the supine position with the following acquisition parameters: tube voltage, 100 kV at auto mA; rotation time, 0.5 s; collimation, 0.25 × 160 mm; and pitch, 1.381. Patients received IV injections of 80 ml Omnipaque-350 contrast at 3.5–4.5 ml/s via IV access, followed by a 40 ml saline flush. Individual contrast optimization was achieved by using a 20 ml test bolus in the right ventricle with a trigger level of 150 HU. An additional delay of 11 s was added before image acquisition in every examination. All scans were reconstructed as 2.0-mm-thick slices with an increment of 2.0 mm.

Chest, abdominal, and pelvic scans that were performed using the Aquilion^™ Precision, Aquilion^™ ONE, Aquilion^™ Prime, and Aquilion^™ 64 CT scanners (manufactured by Canon Medical Systems Corporation, Tochigi, Japan) were used for the analysis of aortic morphology on admission and at the 1-year follow-up. The amount of VFA and subcutaneous fat accumulation (SFA) at the umbilical level was also automatically calculated without exposure to any additional radiation, using the dedicated Synapse Vincent version 4.6.0007 (FUJIFILM Medical, Tokyo, Japan) workstation. Each fat area was reviewed and errors such as trace mistakes were corrected by two cardiologists (Y.M. and S.H.) or one radiologist (T.K.), as necessary.

Vertebrae were scanned using a computed tomography (CT) scanner (Aquilion Precision, Canon, Tokyo, Japan). Bone density (in Hounsfield Units, HU) was measured in the center of a mid-sagittal cross-section to provide a reference bone density of each vertebra tested. DEXA (Hologic Discovery, Hologic Inc, Waltham, MA, USA) was used to quantify the BMD of each vertebra (Apex 3.5.0.1).

U-HRCT (Aquilion Precision™; Canon Medical Systems) and conventional HRCT (Aquilion ONE™; Canon Medical Systems) were used as CT scanners. In U-HRCT, the detector element size is 0.25 × 0.25 mm, with 160 rows and 1792 channels, and the focus size of the X-ray tube is 0.4 × 0.5 mm. On the other hand, in conventional HRCT, the detector element size is 0.5 × 0.5 mm, with 320 rows and 896 channels, and the focus size of the X-ray tube is 0.8 × 0.9 mm. The detector size of the U-HRCT scanner is thus half the size of the conventional CT detector elements in both the x–y plane and the z-axis direction, and the focus size of the X-ray tube in U-HRCT is approximately 1/3 that of conventional HRCT.

Both CRCT and UHRCT are whole-body CT scanners that are generally used in clinical practice. CRCT (Aquilion One, Canon Medical Systems, Otawara, Japan) was only used to obtain ex vivo images of the tiger vertebrae (matrix 512 × 512; slice thickness 0.5 mm; pixel value 350 × 350 μm). Scan parameters were as follows: tube voltage 120 kVp, tube load 100 mAs, and field of view 120 × 120 mm (Table 1). The same imaging range as the micro-CT was used.
The UHRCT scanner (Aquilion Precision, Canon Medical Systems, Otawara, Japan) was used for both tiger vertebrae and human tibiae. For imaging the tiger vertebrae, we used three matrix values (512 × 512, 1024 × 1024, and 2048 × 2048), two slice thicknesses (0.5 mm, 0.25 mm), and pixel values from 150 × 150 μm to 350 × 350 μm. The scan parameters were as follows: tube voltage 120 kVp, tube load 100 mAs, and field of view 120 × 120 mm (Table 1). The imaging range corresponding to the micro-CT was collected. For imaging of the human tibiae, we used two matrix patterns (512 × 512, 1024 × 1024) and two slice thicknesses (0.5 mm, 0.25 mm). The scan parameters were as follows: tube voltage 120 kVp, tube load 101–160 mA, and field of view from 160 × 160 to 260 × 260 mm (Table 2). Consistent with previous studies, the image range was 9 mm and was obtained 22.5 mm from a reference line at the endplate of the distal tibia.