A Longitudinal SPECT Study of Different Patterns of Regional Cerebral Blood Flow in Alzheimer's Disease with or without Diabetes

Aims: To determine the effect of diabetes mellitus (DM) on regional cerebral blood flow (rCBF) patterns in patients with Alzheimer’s disease (AD). Methods: We investigated the initial rCBF of 71 AD patients (36 without DM and 35 with DM) and the final rCBF of 23 AD patients (12 without DM and 11 with DM) after an average of 32 months. Single-photon emission computed tomography (SPECT) data were analyzed by statistical brain imaging. Results: The initial SPECT showed that AD patients without DM had lower rCBF in the left and right inferior temporal gyri than AD patients with DM. A follow-up SPECT demonstrated that rCBF decreased in more widespread regions, including the parietal, temporal, frontal, and limbic lobes, in AD patients without than with DM. Conclusion: This study suggests that functional brain abnormalities in AD differ depending on the DM status at baseline and during follow-up, reflecting neuropathologic differences

Ultrasonic diffraction from a transducer with arbitrary geometry and strength distribution

The exact solution to the Helmholtz equation with a Dirichlet boundary condition is obtained to study three-dimensional ultrasonic diffraction phenomena and derive the numerical data of amplitude loss and the phase shift for correcting induced errors. Calculation is made for near-field diffraction, for the rectangular transducers, and for the transducers with strength distribution on the radiating area. In the near field, where the wavelength and the propagation distance are comparable with each other, the longitudinal and shear waves undergo different diffraction. For transducers having a noncircular shape and a strength distribution on the area, both the amplitude loss and the phase shift experience different tendencies from the classical work on the circular piston source. Use of diffraction data specific to each measurement condition is then necessary to correct the errors. The calculated results are verified for pulse-echo measurements using a shear-wave electromagnetic acoustic transducer.Hirotsugu Ogi, Masahiko Hirao, and Takashi Honda. Ultrasonic diffraction from a transducer with arbitrary geometry and strength distribution. Journal of the Acoustical Society of America, 1995, 98(2), 1191. https://doi.org/10.1121/1.413617

Comparison of Properties of Slow Pathway Potential between Successful and Unsuccessful Radiofrequency Applications in Patients who Underwent Catheter Ablation for Atrioventricular Nodal Reentrant Tachycardia

Findings concerning selective slow pathway radiofrequency ablation for atrioventricular nodal reentrant tachycardia (A VNRT) using the slow pathway potential (SPP) guided method are reported. The electrogram at the SPP recording site showed double potentials consisting of the atrial potential (A) and SPP. However, SPP is usually recorded widely in the right atrial posteroseptal region. To examine whether there was any characteristic marker in the electrogram at the SPP recording site specific to successful RF application, the properties of SPP and its anatomical locations in both successful (S) (38 sites) and unsuccessful (UN) (28 sites) application sites were analyzed in 38 patients who underwent SPP-guided ablation. The distance between the upper margin of the coronary sinus ostium (UCSO) and the ablation catheter (ABL) (DUCSO-ABL) was shorter in S than in UN (2.3 ± 6.3 mm vs. 9.0 ± 5.2 mm below the level of UCSO, p < 0.001). The interval between A and SPP (A-SPP) was longer in S than in UN (44.2 ± 9.9 msec vs. 24.0 ± 7.0 msec, p < 0.001). RF applications at the more anterior sites with longer A-SPP were more successful than at other sites. The sensitivity and specificity of A-SPP (more than 40 msec) were superior to those of DUCSO-ABL (within 5 mm) as the marker for the successful application (sensitivity; 73.7% v.s. 68.4%, specificity; 100% v.s. 82.1 %, respectively). In conclusion, the sites with longer A-SPP might be specific for successful ablation

Coronary Sinus Morphology in Patients with Posteroseptal Atrioventricular Accessory Pathways

Background: There have been numerous reports about coronary sinus (CS) anomalies related to posteroseptal accessory pathways (APs). The purpose of this study was to explore the diameter and morphology of CS in patients with posteroseptal APs. Methods: We performed direct CS angiography in 105 patients with 22 posteroseptal APs and 83 APs in other regions, and 25 control subjects. We compared the diameter of the CS ostium in all subjects, and assessed the correlation of the local activation time in the patients with posteroseptal APs. Results: The proximal size (diameter) of the CS in the patients with posteroseptal APs (13:6 ± 1:1 mm) was larger than that in the patients with other types of APs (10:2 ± 1:8 mm [p < 0:001]) and that in the control subjects (9:6 ± 1:5 mm [p < 0:001]). Dilatation of the CS in the patients with posteroseptal APs extended up to 20 mm inside the CS. In 15 (68%) of the patients with posteroseptal APs, the proximal site of the CS demonstrated a windsock appearance. Conclusions: We concluded that the larger size and the wind cone appearance of proximal CS were unique structural characteristics in most patients with posteroseptal APs