Study of Attenuation Correction Using a Cardiac Dynamic Phantom: Synchronized Time-Phase-Gated Attenuation Correction Method.

In cardiac nuclear medicine examinations, absorption in the body is the main factor in the degradation of the image quality. The Chang and external source methods were used to correct for absorption in the body. However, fundamental studies on attenuation correction for electrocardiogram (ECG)-synchronized CT imaging have not been performed. Therefore, we developed and improved an ECG-synchronized cardiac dynamic phantom and investigated the synchronized time-phase-gated attenuation correction (STPGAC) method using ECG-synchronized SPECT and CT images of the same time phase. Methods: As a basic study, SPECT was performed using synchronized time-phase-gated (STPG) SPECT and non-phase-gated (NPG) SPECT. The attenuation-corrected images were, first, CT images with the same time phase as the ECG waveform of the gated SPECT acquisition (with CT images with the ECG waveform of the CT acquisition as the reference); second, CT images with asynchronous ECG; third, CT images of the 75% region; and fourth, CT images of the 40% region. Results: In the analysis of cardiac function in the phantom experiment, left ventricle ejection fraction (heart rate, 11.5%-13.4%; myocardial wall, 49.8%-55.7%) in the CT images was compared with that in the STPGAC method (heart rate, 11.5%-13.3%; myocardial wall, 49.6%-55.5%), which was closer in value to that of the STPGAC method. In the phantom polar map segment analyses, none of the images showed variability (F (10,10) < 0.5, P = 0.05). All images were correlated (r = 0.824-1.00). Conclusion: In this study, we investigated the STPGAC method using a SPECT/CT system. The STPGAC method showed similar values of cardiac function analysis to the CT images, suggesting that the STPGAC method accurately reconstructed the distribution of blood flow in the myocardial region. However, the target area for attenuation correction of the heart region was smaller than that of the whole body, and changing the gated SPECT conditions and attenuation-corrected images did not affect myocardial blood flow analysis.

Considerations for setting up an order entry system for nuclear medicine tests.

UNLABELLED: Integrating the Healthcare Enterprise-Japan (IHE-J) was established in Japan in 2001 and has been working to standardize health information and make it accessible on the basis of the fundamental Integrating Healthcare Enterprise (IHE) specifications. However, because specialized operations are used in nuclear medicine tests, online sharing of patient information and test order information from the order entry system as shown by the scheduled workflow (SWF) is difficult, making information inconsistent throughout the facility and uniform management of patient information impossible. Therefore, we examined the basic design (subsystem design) for order entry systems, which are considered an important aspect of information management for nuclear medicine tests and needs to be consistent with the system used throughout the rest of the facility. METHODS: There are many items that are required by the subsystem when setting up an order entry system for nuclear medicine tests. Among these items, those that are the most important in the order entry system are constructed using exclusion settings, because of differences in the conditions for using radiopharmaceuticals and contrast agents and appointment frame settings for differences in the imaging method and test items. CONCLUSION: To establish uniform management of patient information for nuclear medicine tests throughout the facility, it is necessary to develop an order entry system with exclusion settings and appointment frames as standard features. Thereby, integration of health information with the Radiology Information System (RIS) or Picture Archiving Communication System (PACS) based on Digital Imaging Communications in Medicine (DICOM) standards and real-time health care assistance can be attained, achieving the IHE agenda of improving health care service and efficiently sharing information.