[Revision of Pelvic Rotation Angle and One Idea for Improving Reproducibility of Hip Joint Radiographic Images (False Profile View)].

Radiographic images of the hip joint can include a false profile view when the foot of the affected side is positioned parallel to the detector plane and the pelvic rotation angle is 65°. However, to the best of our knowledge, pelvic rotation angle has yet to be adequately investigated. The present study aimed to improve radiographic imaging reproducibility by testing pelvic rotation angles using the pubic symphysis and greater trochanter as a guide. The pubic bone angles were 50°-60° independent of gender or age in approximately 70% of 210 hip joints examined by computed tomography. When the line connecting the centers of the femoral neck and the pubic symphysis was based on a detector plane during hip joint magnetic resonance imaging of 12 healthy volunteers, pubic bone angles were approximately 65° and 62° when rotated outwards at 20° and 30°, respectively. Based on the detector plane, the difference between the angle at the intersection of the line connecting the femoral neck center and the pubic symphysis center and the angle at the intersection of the line connecting the pubic symphysis superior margin and the greater trochanter was <4° at external rotation angles of 10°, 20°, and 30°. The foot of the affected side corresponding to the detector plane in front of the body at approximately 65° and the second metatarsal at a pelvic rotation angle when collimated was rotated 25° outwards. Radiation is incident on the pubic symphysis and the greater trochanter can be used as an ejection point.

[A Low-temperature Manganese Chloride Tetrahydrate Improves the Image Quality of Magnetic Resonance Cholangiopancreatography].

Manganese chloride tetrahydrate (MCT) is one of the oral negative contrast agents which is indispensable for imaging of magnetic resonance cholangiopancreatography (MRCP). In this study, improvement of the image quality of MRCP by using low-temperature MCT is verified. All MR imagings were performed using 1.5 T scanner. The T(1) and T(2) values of the different temperature MCTs were measured in the phantom study. Different concentrations of MCT-doped water (30%, 50%, 70%, and 90%) were measured at several temperature conditions (10°C, 15°C, 23°C, 35°C, and 40°C). As a result, the T(1) and T(2) values became larger with a temperature rise. It was more remarkable in low-concentration MCT. Then, 17 healthy subjects were scanned two times with different temperatures of MCT. The MCT of the normal temperature (23°C) and low temperature (10°C) were taken at consecutive 2 days. The contrast between the stomach and the spleen were significantly higher in 2D half Fourier acquisition single shot turbo spin echo (HASTE) images by use of the low-temperature MCT. The contrast between the common bile duct and the adjacent background were significantly higher in the source images of 3D MRCP by use of the low temperature MCT. In addition, 76% of subjects answered in the questionnaire that the low temperature MCT is easier to drink. The low temperature MCT improves the image quality of MRCP and contributes to performing noninvasive examination.

[Evaluation of three-dimensional contrast-enhanced MRA using differential rate k-space sampling (DRKS)].

The progress of three-dimensional (3D) magnetic resonance angiography used in combination with contrast medium (CE-MRA) has been remarkable. Currently, angiography aims at improvements in time resolution without sacrificing spatial resolution. We conducted a basic study of 3D differential rate k-space sampling (DRKS) in which the slice direction of the k-space is divided into two or more areas, the echo data near zero encoding is sampled by a higher time resolution than data in other areas, and reconstruction is done within a short time. This technique involved a problem in which ghost artifacts occur easily when the concentration of contrast medium changes extremely or when signal intensity changes suddenly. This is probably due to a difference in the time to sample data between the low- and high-frequency areas. When we used DRKS to grasp these characteristics, however, it was useful because it allowed reconstruction with an extremely high time resolution.