Improvement of Quantitative Single-Photon Emission Computed Tomography Image Quality by the New Step-and-Shoot Scan Mode

The step-and-shoot (SS) mode and continuous mode are currently used for single-photon emission computed tomography (SPECT) scan mode, and a new scan mode that combines both modes, step-and-shoot plus continuous (SSC) mode, was developed. It is expected to allow a shorter scan time and lower injected dose because the SSC mode is more sensitive than the SS mode. We confirmed the image quality of this scan mode, including various quantitative correction methods for scatter (SC), attenuation (AC), and resolution recovery (RR) in a phantom study and clinical case study. Image quality was evaluated by the count, contrast-to-noise ratio (CNR), and percent of the coefficient of variation (%CV). Independent of the correction methods, the count, CNR, and %CV of the SSC mode were superior to those of the SS mode. The ACSCRR was the best method, with a maximum increased rate of 66.4% in counts and 57.8% in CNR for the 13-mm sphere and 19.6% in CNR for other sphere sizes. The %CV for the SSC mode was the best for AC and ACRR, which was at 15.1%. With regards to attaining short bone SPECT scan time, the combination of the SSC mode and ACRR or ACSCRR demonstrated the best physical performance

Improvement of Quantitative Single-Photon Emission Computed Tomography Image Quality by the New Step-and-Shoot Scan Mode

The step-and-shoot (SS) mode and continuous mode are currently used for single-photon emission computed tomography (SPECT) scan mode, and a new scan mode that combines both modes, step-and-shoot plus continuous (SSC) mode, was developed. It is expected to allow a shorter scan time and lower injected dose because the SSC mode is more sensitive than the SS mode. We confirmed the image quality of this scan mode, including various quantitative correction methods for scatter (SC), attenuation (AC), and resolution recovery (RR) in a phantom study and clinical case study. Image quality was evaluated by the count, contrast-to-noise ratio (CNR), and percent of the coefficient of variation (%CV). Independent of the correction methods, the count, CNR, and %CV of the SSC mode were superior to those of the SS mode. The ACSCRR was the best method, with a maximum increased rate of 66.4% in counts and 57.8% in CNR for the 13-mm sphere and 19.6% in CNR for other sphere sizes. The %CV for the SSC mode was the best for AC and ACRR, which was at 15.1%. With regards to attaining short bone SPECT scan time, the combination of the SSC mode and ACRR or ACSCRR demonstrated the best physical performance

Acute myocardial infarction in Fukushima area of Japan

Although acute myocardial infarction (AMI) is the most serious coronary disease, the background of its onset and the mortality are not fully understood, especially in Japan. From June 1999 to May 2005, we mailed an annual questionnaire to eighteen hospitals in which emergency cardiac catheterization and percutaneous coronary intervention (PCI) were available in the Fukushima area of Japan. A total of 1,590 patients were included. The onset time of AMI had two peaks, i.e., from 9:00 AM to 10:00 AM and 9:00 PM to 10:00 PM. As for reperfusion therapy, four groups were analyzed, the non-reperfusion therapy group (Group N, n = 233), thrombolysis alone group (Group T, n = 80), PCI without thrombolysis group (Group P, n = 1106), and PCI with thrombolysis group (Group TP, n = 151). The in-hospital mortality rate was significantly reduced in Group P (8.4%) compared with that in Group N (33.0%, p < 0.01) and Group T (18.8%, p < 0.01). However, the in-hospital mortality in Group P did not differ from that in Group TP (9.9%). The in-hospital mortality was analyzed by the logistic regression analysis among age, arrival time after onset, peak creatine kinase (CK) values, coronary risk factors, reperfusion therapy, PCI, and thrombolysis. There were significant differences in age (P < 0.01), peak CK values (p < 0.01), hypertension (p < 0.05), and diabetes mellitus (p < 0.01). These results suggest that the onset of AMI may be partly related to human biorhythms, and that PCI would be effective in reducing the in-hospital mortality