Myocardial SPECT Scan Research Articles

The Prognostic Significance of Resting Regional Left Ventricular Function in Patients With Varying Degrees of Myocardial Ischemia.

BackgroundOur aim was to determine whether regional left ventricular (LV) function on a resting transthoracic echo (TTE) provides prognostic information in patients with varying degrees of ischemia on myocardial perfusion imaging.MethodsBetween 2004 - 2009, we identified 503 patients (mean age 69 (SD 11); 79% male) with reversible ischemia on a myocardial SPECT scan who had a TTE within 30 days. We evaluated the rate of subsequent revascularization and death for all patients.ResultsFollowing the SPECT scan and TTE, 246/503(49%) patients underwent revascularization, 64/503 (13%) patients died, 369 (73%) patients had a normal left ventricular ejection fraction (LVEF), 242 (48%) patients had a resting wall motion abnormality (WMA), 21/261 (8%) with no WMA died compared to 43/242 (18%) in patients with a WMA. In patients with a WMA (n = 242) there was no significant difference in mortality when comparing patients with small (< 6 segments) and large (> 6 segments) WMA (P = 0.44). In patients with moderate/severe ischemia, the presence of a resting WMA was associated with a higher mortality rate (18% v 7%; P = 0.005). In a multivariable model, LVEF (< 50%) was associated with a hazard ratio of 2.2 (P = 0.002, 95% CI 1.34 - 3.68) however, WMA and number of abnormal segments did not reach statistical significance.ConclusionA resting wall motion abnormality in patients with moderate/severe ischemia is associated with a higher mortality compared to patients with mild ischemia on myocardial perfusion imaging. Regional left ventricular dysfunction unlike LVEF was not an independent predictor of mortality.

Should HIV-infected patients be screened for silent myocardial ischaemia using gated myocardial perfusion SPECT?

A higher prevalence of cardiovascular risk factors (CRFs) in HIV-infected patients, together with chronic infection and treatments, has resulted in an increased risk of silent myocardial ischaemia (SMI). The objective of this study was to evaluate whether myocardial SPECT should be used for screening HIV-infected patients with no clinical symptoms of coronary artery disease. The prevalence of SMI detected by myocardial SPECT was determined in 94 HIV-infected patients with a normal clinical cardiovascular examination in relation to anthropomorphic parameters, CRFs, inflammatory and HIV infection status, and treatment. Coronary artery disease was detected in nine patients (eight with ischaemia, one with myocardial infarction), corresponding to 9.6 % positivity. All but two of the scintigraphic diagnoses of ischaemia were confirmed by coronarography. Univariate analysis revealed that the overall number of CRFs and the combination of gender and age were associated with a diagnosis of SMI (p < 0.05). According to multivariate analysis, the only independent parameter significantly associated with the scintigraphic diagnosis of SMI was the combination of gender and age (p = 0.01). All the positive myocardial SPECT scans were in men older than 52 years with at least two other CRFs. In this subpopulation of 47 patients, the prevalence of SMI detected by myocardial SPECT reached 19.2 %. In male HIV-infected patients older than 52 years and with at least two other CRFs, screening for SMI using myocardial SPECT was about four times more likely to be positive than in the general population. This may motivate physicians to advise these patients to undergo more systematic screening for SMI using this technique.

Reduced-count myocardial perfusion SPECT with resolution recovery

The aim of this study was to determine whether resolution recovery (RR) iterative reconstruction algorithms can consistently produce diagnostic quality myocardial perfusion SPECT images for the patient population routinely scanned in this department. Reduced-count data were compared with full-count data without RR according to our established protocol. The desired outcome would be to implement the software to allow a reduction in the administered activity for routine myocardial SPECT. Half-count SPECT data were derived from full-count datasets for 53 stress and rest routine myocardial SPECT scans on a GE Infinia camera. Full-count data were reconstructed using standard non-RR ordered subset expectation maximization reconstruction, whereas half-count data were reconstructed using Evolution RR software. Myocardial functional values, image quality and report outcomes of the full-count and half-count reports were compared. Sequential full-time and half-time myocardial SPECT acquisitions were performed for 15 stress and rest studies on a Siemens c.cam dedicated cardiac camera. Half-count data were reconstructed using Siemens Flash 3D RR. No degradation in image quality was found when comparing full-count and half-count studies from the Infinia. Ten percent of the half-count studies from the c.cam were considered slightly worse than full-count data. Statistically significant differences in some full-count versus half-count functional values were found but the actual mean differences were not considered clinically significant. No difference was found for 44 out of 53 full-count versus half-count reports, a minor difference for seven out of 53 and a significant difference in two cases. RR was found to produce diagnostic image quality for nearly all scans, but it was felt that a reduction of 50% from our standard protocol was too great. A proposed reduction of 33% administered activity was considered acceptable to produce consistently adequate diagnostic images for both manufacturers.

The relationship between Myocardial SPECT and Fractional Flow Reserve: Is it drifting apart?

In the paper, Tc-99 m sestamibi single photon emission computed tomography for guiding percutaneous coronary intervention in patients with multivessel disease: a comparison with quantitative coronary angiography and fractional flow reserve by Forster et.al. the authors correctly point out that FFR (Fractional Flow Reserve) was initially validated against non-invasive studies which included Thallium SPECT, Stress Echocardiography and standard exercise testing. In the paper by Pijls et.al.in 1995 which was one of the first validation studies of FFR [1] there were a significant number of negative SPECT and stress echo results at FFR values significantly lower than .75 although in all patients myocardial ischaemia was demonstrated on one of the three tests used. In the same study two patients had positive exercise tests and one patient a positive Thallium SPECT scan with FFR values significantly above .75. Later studies have confirmed that a FFR results can have a prognostic significance which can be better than SPECT in a selected group of patients with untreated intermediate lesions after PCI of a severe lesion [2]. In contrast SPECT itself has a significant prognostic value in patients with low or intermediate risk of coronary disease and has been recommended as a first line diagnostic method in coronary disease by the UK National Institute of Clinical Excellence (http:// www.nice.org.uk/nicemedia/pdf/TA073guidance.pdf). A normal Myocardial SPECT scan has been shown in large studies to have a very good prognostic value with adverse event rates of 0.6%/year quoted in one study of 7,376 consecutive patients [3]. The prognostic value of SPECT scanning may be improved by using cardiac gating [4] and when ejection fraction and end-systolic volumes are also considered as additional data the overall prognostic value of SPECT scanning improves further [5]. The patient conditions under which FFR is measured also have to be taken into account. In this study the patients had multivessel disease. Although a single stenosis in each vessel would not modify the result multiple stenoses in a vessel require a modified approach to FFR measurement [6] and patients with a prior myocardial infarction resulting in microvascular dysfunction [7] may also have a falsely elevated FFR but usually by 5% however in chronic myocardial infarction FFR may still be accurate [8]. So can the relative merits of these two tests be put into perspective? How also should we view the role of QCA (quantitative coronary angiography) in this context? This study concludes that SPECT gives a Editorial comment on the article of Forster et al. (doi:10.1007/s10554-009-9510-x).

P27 Does an increase in administered activity produce a significant improvement in the image quality in relation to the myocardial SPECT scan?

Diana, Princess of Wales Hospital, Grimsby, UK Abstracts for the Autumn Meeting of the British Nuclear Medicine Society Cambridge, UK, 4–5 September 2006