Single Photon Emission Computed Tomography Results Research Articles

Exercise echocardiography versus thallium-201 SPECT for assessing patients before and after PTCA.

This study was designed (1) to assess the relationship between stress exercise echocardiography (echo) and 201-Tl single photon emission computed tomography (SPECT) applied simultaneously in 23 patients who were candidates to percutaneous transluminal coronary angioplasty (PTCA), (2) to assess the relationship between the development of exercise-induced wall motion abnormalities, transient perfusion defects and the severity of quantitatively assessed coronary stenoses and (3) to compare the functional improvement after PTCA by exercise echo and SPECT. Before PTCA there was an agreement of 78% between stress echo (new wall motion abnormalities) and SPECT (transient perfusion defects) results. All patients with a percentage diameter stenosis greater than 70% had a positive echo and SPECT, while they were both negative if the percentage diameter stenosis was less than 50%. In 19 patients re-studied 4 weeks after PTCA, an ischaemic response at stress echo was found in two of the 13 patients who had a positive stress echo test before PTCA, and SPECT was still positive in three of the 10 patients who had a positive SPECT study before PTCA. Echo and SPECT were concordant in 17/19 cases. It is concluded that exercise echo and 201-Tl SPECT are useful non-invasive tools for the functional assessment of patients before and after PTCA, and that they provide highly concordant results.

Mapping the distribution of amobarbital sodium in the intracarotid Wada test by use of Tc-99m HMPAO with SPECT.

The intracarotid amobarbital sodium, or Wada, test has been used to localize speech and memory function prior to surgical treatment of temporal lobe seizures. The authors mixed technetium-99m hexamethyl-propyleneamine oxime (HMPAO) with amobarbital sodium and injected the mixture in 25 patients with epilepsy. Single photon emission computed tomography (SPECT) of the brain was then performed to determine intracerebral distribution of the amobarbital sodium. Results of SPECT were compared with those of conventional and digital subtraction angiography (DSA). The distribution of Tc-99m HMPAO and, presumably, amobarbital sodium varied from patient to patient. SPECT revealed a statistically different distribution from that predicted with conventional angiography. The distribution also often differed from that of DSA, although the difference was not significant. SPECT revealed infrequent delivery to mesial temporal lobe structures. This emphasizes the need for caution in the use of the intracarotid amobarbital sodium test to predict the outcome of removal of these areas.

Exercise echocardiography and technetium-99m MIBI single-photon emission computed tomography in the detection of coronary artery disease

To compare the relative diagnostic value of exercise echocardiography with perfusion technetium-99m metoxyisobutylisonitrile single-photon emission computed tomography (SPECT) in detecting coronary artery disease (CAD), 75 patients with suspected CAD but a normal electrocardiogram (ECG) at rest were included in a prospective correlative study. Both the exercise echocardiograms and SPECT studies were performed in conjunction with the same symptom-limited bicycle exercise test. The development of either a new wall motion abnormality or a reversible perfusion defect after exercise, or both, were regarded as a positive test for the exercise echocardiographic and SPECT studies, respectively. The results of these 2 diagnostic tests were compared with coronary arteriography. Exercise echocardiography identified 35 (71%) and SPECT 41 (84%, p = 0.13) of the 49 patients with significant CAD (defined as >50% diameter stenosis). Twenty-five of the 26 patients (96%) without significant coronary stenosis had negative exercise echocardiographic results and 23 of 26 (88%) had negative SPECT results. Exercise-induced new wall motion abnormalities showed a good correlation with reversible perfusion defects, and the results of the 2 methods were concordant in 65 of 75 patients (agreement = 88%, κ = 0.75 ±0.14). Both the diagnostic accuracy of exercise echocardiography and SPECT were significantly higher than the exercise ECG (81 vs 64%, p < 0.02 and 88 vs 64%, p < 0.005). The sensitivity and specificity for detecting individual diseased vessels were 60 and 95% for exercise echocardiography and 67 and 94% for SPECT. However, in the 33 patients with 1-vessel disease, exercise echocardiography showed a lower sensitivity when compared with SPECT (61 vs 82%, p < 0.02). SPECT was tendentially more sensitive than exercise echocardiography in detecting isolated left circumflex coronary artery stenoses.