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The acquisition of radiotherapy planning scans on positron emission tomography (PET)-CT scanners requires the involvement of radiotherapy radiographers. This study assessed the radiation dose received by these radiographers during this process. Radiotherapy planning 18F-fluorodeoxyglucose (18F-FDG) PET-CT scans were acquired for 28 non-small cell lung cancer patients. In order to minimise the radiation dose received, a two-stage process was used in which the most time- consuming part of the set-up was performed before the patient received their 18F-FDG injection. Throughout this process, the radiographers wore electronic personal dosemeters and recorded the doses received at different stages of the process. The mean total radiation dose received by a radiotherapy radiographer was 5.1 ±2.6 μSv per patient. The use of the two-stage process reduced the time spent in close proximity to the patient by approximately a factor of four. The two-stage process was effective in keeping radiation dose to a minimum. The use of a pre-injection set-up session reduces the radiation dose to the radiotherapy radiographers because of their involvement in PET-CT radiotherapy treatment planning scans by approximately a factor of three. [ABSTRACT FROM AUTHOR]

Electrocardiogram gated single photon emission computed tomography of the intracardiac blood pools is a recent development that involves the acquisition of images in multiple projections after in vivo erythrocyte labelling with technetium-99m and reconstruction of these images into tomographic sections in any desired plane. The technique was used in 25 subjects to measure left ventricular volume, by summing the areas of the ventricle in each of the tomographic sections, and the results compared with those using a counts based (non-geometric) technique from planar radionuclide ventriculography. Endocardium was defined with the aid of a contour at 43% of maximum left ventricular counts, and this contour was validated for a left ventricular phantom. Correlation between tomographic and counts based left ventricular volume was close. Similarly, ejection fraction correlated well. The technique is therefore an accurate method for determining left ventricular volume and ejection fraction, avoiding the assumptions about shape made by other geometric methods. [ABSTRACT FROM PUBLISHER]

Thirty-three subjects were studied by first pass radionuclide angiography. The extrapolated monoexponential tracer washout slopes from septal, lateral, and apical segments of the left ventricle were measured. In 13 subjects with normal left ventricles, as assessed by ejection fraction estimation and phase analysis, there was no difference between septal and lateral segments but, in each case, apical washout was significantly prolonged. In 20 subjects with abnormal ventricles washouts were, in general, slower than those of the normal ventricles. Apical washout was still the slowest but the difference between base and apex was less pronounced. In contrast to the normal ventricles, differences appeared between septal and lateral segments. The left ventricle is a poor mixing chamber. Pools of relative stasis exist at the apex of both normal and abnormal ventricles and within the body of the chamber in the latter. [ABSTRACT FROM PUBLISHER]

A study was undertaken to evaluate the role of positive infarct scintigraphy in the diagnosis of acute myocardial infarction (AMI), using Technetium99m stannous pyrophosphate (Tc-PYP) and a portable gamma camera. Sixty-one patients admitted to the Coronary Care Unit (CCU) with a presumptive diagnosis of AMI or ischaemic cardiac pain were studied. Positive scans were present in 24/25 (96%) patients with AMI and new Q waves, and in 10/12 (83%) patients with AMI and no Q waves. Nine of eleven (82%) patients with chest pain and no infarction had negative scans. Of thirteen patients with unstable angina, ten (77%) had positive scans. A further eight patients undergoing coronary artery bypass surgery for angina pectoris were studied pre- and postoperatively. Two patients had strongly positive postoperative scans. The Tc-PYP scan is valuable in the detection of peri-operative infarction following coronary artery surgery, and in patients with unstable angina the technique may detect small amounts of myocardial necrosis undetectable by more conventional means. When the diagnosis of infarction is obvious from the ECG, enzymes, or a combination of the two, the Tc-PYP scan provides no extra information helpful in patient management. [ABSTRACT FROM AUTHOR]

Fifty-two subjects with suspected coronary artery disease were studied by first pass radionuclide angiocardiography using a single crystal gamma camera. Phase analysis, a new technique which can detect ventricular regions with abnormal emptying patterns, was applied to the resulting left ventricular radionuclide angiocardiograms. Eighteen turned out be normal and in these subjects the variation of phase values in each of eight ventricular segments was established. Thirty-four had coronary artery disease. By comparison with the normal subjects, 21 had at least one segment with an abnormally high phase value. Such high values were associated with low values of ejection fraction, as determined by a radionuclide technique, total occlusion of a major coronary artery and significant wall motion abnormalities on the radiographic ventriculogram. A comparison between phase analysis and wall motion on a regional basis disclosed progressively high phase values with increasing severity of wall motion abnormality. Particularly high values were found in association with ventricular aneurysm. Phase analysis of first pass radionuclide angiocardiograms is a valid method for the detection of regional abnormalities of ventricular contraction in coronary artery disease. [ABSTRACT FROM PUBLISHER]

Seventy subjects with suspected coronary artery disease were studied by radionuclide angiocardiography. Delayed or paradoxically emptying regions of the left ventricle were detected by a relatively new nuclear technique--phase imaging. The results were assessed in the light of cardiac catheterisation findings. Compared with 19 normals, regions with abnormally high phase (and therefore late emptying) were found in 42 of 61 subjects with coronary disease. High phase values were associated with total occlusion of a major coronary artery, low ejection fraction, and extensive wall motion abnormalities. The phase image greatly facilitated the calculation of contractile segment ejection fraction in 14 cases of left ventricular aneurysm. In three of these postoperative left ventricular ejection fraction agreed closely with preoperative contractile segment ejection fraction and there was a distinct improvement in the phase image after aneurysmectomy. [ABSTRACT FROM PUBLISHER]

Thirteen patients with left ventricular aneurysms complicating myocardial infarction were studied by contrast angiography and by first pass radionuclide ventriculography. The ejection fraction of the contractile segment (EFCS) was measured from both studies using a double hemishperoid model, and the values correlated closely. There was a monotonic relation between EFCS and stroke volume index measured from thermodilution cardiac outputs carried out simultaneously with the radionuclide study. When radionuclide ventriculography was performed at submaximal supine exercise, changes in EFCS paralleled changes in the total left ventricular ejection fraction in 10 of the 13 cases. In nine patients, changes in EFCS paralleled changes in stroke volume index and the relation between EFCS and stroke volume index was maintained at exercise. After administration of the vasodilator isosorbide dinitrate to 12 patients, repeat exercise radionuclide ventriculography showed an improvement in left ventricular ejection fraction and in eight patients EFCS improved. First pass radionuclide ventriculography can accurately estimate EFCS, which may be an important factor in predicting the likely response to aneurysmectomy. Changes in EFCS on exercise are reflected in changes in total left ventricular ejection fraction and stroke volume index. Isosorbide dinitrate may improve contractile segment function on exercise. [ABSTRACT FROM PUBLISHER]

Eighteen patients with a history of previous anterior myocardial infarction and suspected left ventricular aneurysms were studied both by contrast left ventriculography and by first pass radionuclide ventriculography using Technetium99m and a computerised multicrystal gamma camera. The radionuclide study successfully identified all 14 patients with aneurysms and all 4 with diffusely hypo-kinetic ventricles. Ejection fraction calculated from the change in radioactive counts in the left ventricle correlated well with that calculated from the area-length method from the contrast angiogram (r = 0.83). Ventricular volumes calculated from the area-length formula for both contrast and radionuclide angiograms correlated closely (r = 0.85 and r = 0.89 for end-systolic and end-diastolic volumes, respectively). In the patients with aneurysms, there was a close correlation between the extent of akinesis, as assessed by the two methods (r = 0.94). The ability of the radionuclide ventriculogram to provide accurate information on global and segmental ventricular function, and to differentiate between segmental and diffuse ventricular dysfunction, enables the method to act as a screening procedure in the investigation of patients with suspected left ventricular aneurysms. [ABSTRACT FROM PUBLISHER]