Quantitative scintigraphic display of myocardial blood flow

Abstract

Immediately after coronarography 10 mCi 133Xenon were injected into the left or right coronary artery. A scintillation camera was placed above the thorax of the patient. A computer unit (KRUPP EPR 2500) with magnetic tapes and discs is available for data processing and data storage. Sequential images of the heart are taken over a period of 2 min in a two-second-frame mode and stored on magnetic tape. The total image was divided into 5 - 5 mm areas. From each area a functional curve was registered and the Myocardial Blood Flow (ml/min/100 g myocard) could be calculated from that. For a precise evaluation of the image of the Myocardial Blood Flow, any influences originating from other regions of the body had to be excluded. Therefore all curves are rejected which did not (a) reach their maximum value within 15s after injection, or (b) where the maximum was less than 10% of the highest maximum value of the reference curve. The values of the Myocardial Blood Flow calculated in this manner are displayed on a TV-screen. These values can be transformed into 10 colors or grey levels. This method has been proven to be useful in clinical practice for functional studies, especially for the judgement of the effectivity of pharmaceuticals. The quantitative display technique of the "Myocardial Blood Flow" improves the clinical statement in comparison to a scintigraphic picture.

Clinical Application and Results of the Assessment of Coronary Blood Flow by the Regional Precordial Xenon Residue Detection Technique

“…The system employed at the Hannover Medical School consists of a Pho-gamma 3 camera (Nuclear Chicago), using a 64 x 64 matrix, approximately 400 to 600 matrix points corresponding to the area of the heart, in connection with a CDC 1700 computer (32 K, 16 bites, two disc and magnetic tape units, the deadtime of the entire system amounting to 4 jj.sec). 10 mCi 133 Xe (0.5 ml) are injected selectively into the main left or right coronary artery as described earlier (24,19); when necessary, the injections are repeated up to six times at an interval of 15 min. The frame rate amounts to 2 sec during the first, and to 5 sec during the second minute after injection; this results in 42 individual pictures per examination with a maximum count rate of 400 to 500 per matrix point.…”

“…For most cases, this proves to be still within the first monoexponential slope of the wash-out, except in the presence of very high flow rates. Calculation of myocardial blood flow follows the well-known equations for external monitoring and single bolus injections (1,19,21,24,33,34,39,45). Myocardial blood flow is displayed for each matrix point both numerically in ml/min/100 g myocardium and as an analog signal, that is a so-called "flow image" indicating the heights of flow in gradations of different grey steps or different colors, the steps representing 10% of flow differences (Figs.…”

“…flow from the entire heart. A further and decisive step was therefore achieved with the clinical use of gamma scinticameras in the early 1970's which, in connection with data processing systems, allowed the recording of flow from various normal and abnormal regions of the heart, that is the assessment of regional myocardial blood flow (3,8,19,33). In spite of the vast technical progress made in this field during the past few years, there are, however, still many unresolved methodological problems concerning the recording of regional myocardial blood flow, still necessitating a cautious interpretation of the results.…”

Transmural myocardial infarction in young women taking oral contraceptives. Evidence of reduced regional coronary flow in spite of normal coronary arteries.

“…Left ventriculograms were performed in 45 degree RAO-projections. In 3 of the 4 patients, regional myocardial perfusion was analysed both by (1) the Xenon residue detection technique (Ross et al, 1964;Dwyer et al, 1973;Hundeshagen et al, 1976); and (2) by microsphere perfusion scintigraphy (Ashburn et al, 1971).…”