Coronary Artery Stent Evaluation Using a Vascular Model at 64-Detector Row CT: Comparison between Prospective and Retrospective ECG-Gated Axial Scans

OBJECTIVE: We wanted to evaluate the performance of prospective electrocardiogram (ECG)-gated axial scans for assessing coronary stents as compared with retrospective ECG-gated helical scans. MATERIALS AND METHODS: As for a vascular model of the coronary artery, a tube of approximately 2.5-mm inner diameter was adopted and as for stents, three (Bx-Velocity, Express2, and Micro Driver) different kinds of stents were inserted into the tube. Both patent and stenotic models of coronary artery were made by instillating different attenuation (396 vs. 79 Hounsfield unit [HU]) of contrast medium within the tube in tube model. The models were scanned with two types of scan methods with a simulated ECG of 60 beats per minute and using display field of views (FOVs) of 9 and 18 cm. We evaluated the in-stent stenosis visually, and we measured the attenuation values and the diameter of the patent stent lumen. RESULTS: The visualization of the stent lumen of the vascular models was improved with using the prospective ECG-gated axial scans and a 9-cm FOV. The inner diameters of the vascular models were underestimated with mean measurement errors of -1.10 to -1.36 mm. The measurement errors were smaller with using the prospective ECG-gated axial scans (Bx-Velocity and Express2, p < 0.0001; Micro Driver, p = 0.0004) and a 9-cm FOV (all stents: p < 0.0001), as compared with the other conditions, respectively. The luminal attenuation value was overestimated in each condition. For the luminal attenuation measurement, the use of prospective ECG-gated axial scans provided less measurement error compared with the retrospective ECG-gated helical scans (all stents: p < 0.0001), and the use of a 9-cm FOV tended to decrease the measurement error. CONCLUSION: The visualization of coronary stents is improved by the use of prospective ECG-gated axial scans and using a small FOV with reduced blooming artifacts and increased spatial resolution.

Recording Medical-Student Attendance with a Fingerprint Recording System / 医学教育

A trial of a fingerprint recording system (FPRS) to precisely record class attendance was carried out with third-year students at our medical school. Along with this new system, a conventional card method was used to confirm attendance. The FPRS consists of a fingerprint recording unit, a communication control unit, and a personal computer. Each student was required to register a fingerprint before the trial started. Attendance was recorded by placing the registered finger on the fingerprint recording unit. The recording, comprising each student's name and the time, was stored in the communication control unit and transferred to the personal computer through the RS-232 cable. The RS-232 cable can be replaced with an Internet environment. In the trial performed in a pharmacology course, 95 medical students were enrolled, and the total student-lecture number was 3008. On 149 occasions students forgot to record their fingerprints. One student reported that his fingerprint was not recognized by the recording unit. However, the problem was solved when he registered his fingerprint again. The attendance recorded by the conventional method confirmed that recorded by the FPRS. After completion of the trial, 26 students volunteered to give their impressions about the FPRS. They were divided on the basis of their impressions ( “positive”, “negative”, and “conditionally positive” ) into three groups of approximately equal number. The observations suggest that the impression of the FPRS varies among students and that this variation is unrelated to either student performance or the attendance rate. This trial found no major technical problems in recording attendance with the FPRS.