Biomedical subjects

A C Otto

Publications and source records attributed to A C Otto.

38 records · Page 3Linked to original sources

PubMedDate not supplied

Left ventricular ejection fraction calculated from gated technetium-99-sestamibi SPECT.

BACKGROUND: The accuracy of the left ventricular ejection fraction (LVEF) calculated from gated single photon emission computed tomography (GSPECT) studies is dependent on the accuracy of the determination of the end-diastolic volume (EDV) and end-systolic volume (ESV) of the left ventricle (LV). In this study we evaluated the feasibility of calculating the EDV, ESV and LVEF from the area under the polar graph (APC) of the edges of the LV image determined by a first derivative edge-detection method. METHODS AND RESULTS: Technetium-99m ((99m)Tc) sestamibi GSPECT studies and planar equilibrium radionuclide ventriculography (ERNV) were performed on 15 male subjects in whom the LVEF ranged from 19% to 75%. Images were reconstructed to obtain short axis slices of the LV spanning the cardiac cycle. On each slice the LV edge points were determined at 10 degrees intervals using the APC method. The area of each short axis slice was determined by conversion to polar co-ordinates, interpolation and numerical integration of the graphs and multiplication by a pre-determined conversion factor. RESULTS: Edges were successfully determined in all 15 patients using the APC method. The LVEF results correlate well with conventional planar ERNV studies (r = 0.96, LVEF(GSPECT) = 8.80 + 0.66 LVEF( ERNV)). The absolute difference between the LVEF for ERNV and for the APC method was 6.1% with a standard deviation of 7.6%. The reproducibility of SPECT LVEF using the APC method was good (intra-observer r = 0.99, inter-observer r = 0.99). CONCLUSIONS: The APC method provides for easy and accurate ejection fraction determination with limited underlying mathematical assumptions. The ability to interpolate the edge points provides for stable edge detection even in hypoperfused myocardium.

Adult↗

PubMedDate not supplied

Evaluation of exercise-induced stunning using myocardial perfusion imaging.

A late reduction (i.e. 1 hour post exercise) in left ventricular ejection fraction (LVEF) in patients with ischaemic heart disease was recently reported with radionuclide myocardial perfusion imaging (MPI). This was ascribed to possible stunning provoked by exercise-induced ischaemia. The purpose of this retrospective study was to evaluate the possible relationship between exercise-induced ischaemia and late (1 hour) post-exercise myocardial stunning. Forty-eight patients who underwent standard treadmill exercise with 99m Tc-MIBI MPI were analysed according to their rest and stress perfusion images. A normal group of 15 subjects, 23 patients with previous infarction and 10 with objective evidence of ischaemia were identified. Absolute change, i.e. exercise LVEF minus rest LVEF, and relative change, i.e. absolute change divided by resting LVEF (expressed as a percentage) were determined. The mean absolute change in LVEF was not significant within the normal and infarction groups but was statistically significant within the ischaemic group. The mean relative ( %) change within the normal and infarction groups was not significant, but was significant within the ischaemic group. The difference in mean absolute changes between the normal and infarction group was not significant but both these groups were statistically different when compared with the ischaemic group. No statistically significant difference in mean relative changes was found between the normal and infarction groups. The mean relative change in the ischaemic group tended to be larger than in the infarction group. The presence of a late regional wall motion abnormality or decreased LVEF after exercise (i.e. stunning) may be an important additional indicator of underlying myocardial ischaemia.

Adult↗