[en] Image contrast, photon noise and sampling frequency limit the visual extraction of relevant temporal information in scintigraphic image series. When the Unitation is mainly due to low temporal contrast, temporal contrast enhancement will strongly improve the perceptibility of time patterns in the series. When the limitation is due to photon noise and limited temporal sampling, parametric imaging by means of the Hadamard transform can visualise temporal patterns. (WU)

[en] This paper situates the different approaches to visualise dynamic time patterns in a general framework, introduces a new method for the visual assessment of dynamic time patterns, and proposes an alternative to standard Fourier functional imaging

No abstract available

[en] Temporal Fourier analysis on a time series on images concentrates on the change in information contained in each picture element as a function of time. A TFT limited to the first Fourier coefficients, will yield two functional images, the amplitude and the phase, respectively. In the case of periodic phenomena such as the beating of the heart or the breathing of the lungs amplitude and phase are the most characteristic parameters available for functional imaging. In gated cardiac blood pool studies, count rate derived functional images allow a great accuracy in the detection and localisation of asynergy. Any transient function f(x) wich is not periodic but defined within an internal (-T,T) can be made periodically by defining f(t + 2T) = f(t). TFT can then be applied to study such phenomena as first pass blood flow. The amplitude image corresponds to the changes in counts within the image series, the phase images to the time of transit. The two functional images will permit a rapid and sensitive assessment of the vascularisation of various structures or lesions. As a rule, the information content in a dynamic series of images is used with maximal efficiency. This highly increases the resolution in time and space of studies limited by poor count rate statistics as compared with other functional imaging techniques

[en] A new technique based on computerized gamma densitography and tomography is described. The technique allows the local study of the breathing mechanism of the lung (expansion magnitude and timing) and of vascular pulsations (distribution and magnitude). Dynamic changes in the shape of the lung and chestwall are studied by means tomograhic reconstructions. Dynamic changes in transmission of x or γ rays through the lungs stem principally from local expansion perpendicular to the direction of the transmission during the respiratory cycle, from organ displacement associated with the respiration and from local variations is bloodvolume due to vascular pulsations. We propose the following detection technique: the transmission images are obtained with a 5-10 mCi Tc - 99m point source at 2 m from the crystal plane of a large field of view gamma camera without collimator. Hence, the camera is used at maximum sensitivity and at intrinsic resolution. The information density obtained by the proposed transmission densitometric technique is high enough to allow the quantitative study of the amplitude and timing of local lung expansion, and the regional distribution and from of vascular pulsation. Using the same detection technique, tomographic reconstructions of the lungs are easily obtained

No abstract available

No abstract available