Combined evaluation of rest-redistribution thallium-201 tomography and low-dose dobutamine echocardiography enhances the identification of viable myocardium in patients with chronic coronary artery disease

99mTc-sestamibi SPECT/CT and 18F-FDG-PET/CT have similar performance but different imaging patterns in newly diagnosed multiple myeloma

PURPOSE

F-fluorodeoxiglucose (F-FDG)-PET/CT has been widely used to evaluate multiple myeloma. Tc-sestamibi (MIBI) scintigraphy has also been proposed for assessing multiple myeloma, but its use with state-of-the-art single-photon emission computed tomography/computed tomography (SPECT/CT) technology has not been fully evaluated.This study aimed to compare these two imaging modalities in multiple myeloma staging.

MATERIALS AND METHODS

Sixty-two patients with recently diagnosed multiple myeloma were submitted to whole-body F-FDG-PET/CT and whole-body MIBI scans plus SPECT/CT of the chest and abdomen/pelvis. Number of focal lesions, contiguous soft tissue involvement (CSTI), extramedullary lesions (EMLs) and diffuse bone marrow (BM) involvement were recorded.

RESULTS

PET/CT was positive in 59 patients (95%) and MIBI SPECT/CT in 58 (93%) (P = 0.69). MIBI detected more diffuse bone marrow involvement than PET/CT (respectively 78 vs. 58% of the patients), while PET/CT demonstrated more focal lesions than MIBI SPECT/CT (81 vs. 54% of the patients) (P = 0.002). PET/CT detected EMLs in four subjects and MIBI in one subject. CSTI was found in 28 (45%) and 23 (37%) patients on PET/CT and MIBI images, respectively (P = 0.36). Three patients with lytic lesions and no FDG uptake were MIBI positive, and two subjects with lytic lesions without MIBI uptake were FDG positive.

CONCLUSION

MIBI SPECT/CT performs similarly to F-FDG-PET/CT in identifying sites of active disease in multiple myeloma staging. MIBI is more efficient than FDG for detecting the diffuse involvement of bone marrow but less efficient for detecting focal lesions. Some patients presented a 'mismatch' pattern of FDG/MIBI uptake.

Twenty-four-hour thallium-201 imaging enhances the detection of myocardial ischemia and viability after myocardial infarction: a comparison study with echocardiography follow-up

BACKGROUND

To explore the value of 24 hour late Tl-201 imaging for detection of myocardial ischemia/viability after myocardial infarction.

MATERIALS AND METHODS

Thirty-eighty patients with myocardial infarction underwent immediate, 3 hour redistribution and 24-hour late imaging after intravenous injection of 5 mCi Tl-201. Image quality analysis was performed using a 4-grade model. The immediate/redistribution, redistribution/late, and immediate/late Tl-201 images were analyzed double-blinded. The capability of detection of myocardial ischemia/viability was compared between the 3 hour redistribution and the 24-hour late imaging. Thirty-two patients underwent coronary angiography and successful revascularization of stenotic coronary arteries. The relationship between the severity of coronary artery stenosis and the time to completed redistribution of myocardial perfusion defects after resting injection of Tl-201 was investigated. The sensitivity, specificity, and accuracy for predicting an improvement in function post revascularization were compared between the 24-hour late imaging and the 3-hour redistribution imaging by way of a follow-up echocardiography.

RESULTS

Three hour redistribution and 24-hour late imaging showed no significant differences in image quality according to the 4-grade model (P = 0.3580). Of 194 abnormal segments based on immediate Tl-201 imaging, redistribution imaging showed 60 reversible segments, taking up 31% (60/94), and late imaging showed 86 reversible segments, taking up 44% (86/194), with a significant difference (P = 0.0064). Of 128 severely abnormal segments, redistribution imaging showed 32 reversible segments, taking up 25% (32/128), and late imaging showed 48 reversible segments, taking up 38% (48/128), with a significant difference (P = 0.0310). Of 66 mildly abnormal segments, redistribution imaging showed 28 reversible segments, taking up 42% (28/66), and late imaging showed 38 reversible segments, taking up 58% (38/66), with no significant difference. Twenty-four hour late imaging showed an additional 30 reversible segments, taking up 22% (30/134) among 134 abnormal segments based on the immediate Tl-201 imaging, which did not improve on 3-hour redistribution imaging. The coronary arteries supplying the reversible segments detected by the 24-hour late imaging were more severe in diameter stenosis than those supplying the reversible segments detected by the 3-hour redistribution imaging. The sensitivity, specificity, and accuracy for predicting the functional improvement after the revascularization were 93% and 83%, 80% and 78%, 86% and 78%, respectively, by the 24-hour late imaging and the 3-hour redistribution imaging correspondingly, with the former being superior to the latter on the basis of the evaluation results of 9.90 +/- 3.62 months of follow-up echocardiography (chi = 10.8655, P = 0.0010).

CONCLUSION

Twenty-four hour late Tl-201 imaging, with satisfactory image quality, enhances the detection of myocardial ischemia/viability after myocardial infarction.

Prognostic role of single-photon emission computed tomography (SPECT) imaging in myocardial viability

PURPOSE OF REVIEW

Cardiac imaging is evolving rapidly. Appropriate use of this technology could reduce morbidity and mortality, but inappropriate use could have a significant financial burden. Single-photon emission computed tomography imaging is widely available. This review summarizes the clinical utility and limitations of the prognostic role of single-photon emission computed tomography imaging for myocardial viability in patients with coronary artery disease and left-ventricular dysfunction.

RECENT FINDINGS

201Tl single-photon emission computed tomography, 99mTc single-photon emission computed tomography with sestamibi or tetrofosmin, and 18F-fluorodeoxyglucose single-photon emission computed tomography are validated tools for assessing myocardial viability. These techniques have a very similar predictive value in determining regional and global response to revascularization. 201Tl single-photon emission computed tomography viability studies are predictive of reverse left-ventricular remodeling, symptom improvement, and patient outcome after revascularization. Combination imaging with dual-isotope simultaneous acquisition single-photon emission computed tomography or positron-emission tomography/single-photon emission computed tomography may improve the positive and negative predictive values of single-photon emission computed tomography-based viability studies.

SUMMARY

Single-photon emission computed tomography-based myocardial viability testing is an important diagnostic modality due to widespread availability and reasonably good sensitivity and specificity for detecting viable myocardium and predicting clinical and functional responses to revascularization. In the future single-photon emission computed tomography viability techniques may have a prognostic role in predicting responses to cardiac resynchronization therapy and evaluating myocardial stem-cell transplantation.

Myocardial Viability: Nuclear Assessment

There are an estimated 5 million patients with congestive heart failure (CHF) in the United States. The long-term outcome in these patients is poor with a 5-year mortality of 70%. There is evidence suggesting that revascularization in patients with viable myocardium can result in reduced event rate in these patients. The presence of viable myocardium best identifies patients who will improve with revascularization. Noninvasive imaging with radionuclide tracers has been used extensively to identify the presence and extent of viable myocardium. We have summarized the role of radionuclide myocardial perfusion and function evaluation in assessment of viable myocardium in this review.

Value of low-dose dobutamine addition to routine dual isotope gated SPECT myocardial imaging in patients with healed myocardial infarction or abnormal wall thickening by echocardiogram

There is overlap in myocardial viability detection by thallium-201 uptake and contractile reserve (CR) using low-dose dobutamine (LDD). The dual isotope protocol was modified in this study by acquiring thallium-201 images using LDD to enhance viability detection in addition to coronary flow reserve assessment. One hundred twenty-four patients with coronary disease underwent gated single-photon emission computed tomographic thallium-201 imaging at rest with LDD (10 microg/kg/min) during acquisition followed by stress technetium-99m sestamibi myocardial perfusion (MP) imaging with dobutamine, adenosine, or treadmill exercise. F-18-fluorodeoxyglucose (FDG) positron emission tomography was obtained in 41 patients. Myocardial perfusion (MP) imaging was divided into normal, fixed, and ischemic segments, and subclassified by wall motion and/or thickening changes between 1-hour poststress and LDD into normal, fixed, or improved dysfunctional segments (CR present). Mean left ventricular ejection fraction was 39% at 1 hour after stress and 47% with LDD (p <0.001). In dysfunctional myocardium, CR was significantly higher (p <0.001) in ischemic (233 of 368) and fixed segments (150 of 335) than in normal MP segments (43 of 220). Combined MP and CR analysis showed higher accuracy and negative predictive value in identifying FDG-viable myocardium than either method alone, whereas a high positive predictive value was maintained, similar to both markers. Quantitative analysis showed significant increased wall motion and thickening with LDD compared with 1 hour after stress, which was highest in ischemic segments and lowest in fixed segments. Thus, LDD dual isotope is a practical protocol that improves viability detection by simultaneous MP and CR analysis in addition to coronary flow reserve assessment in 1 study. Moreover, it requires no extra imaging time or radioactivity than the routine protocol.

Prognostic value of myocardial viability determined by a 201Tl SPECT study in patients with previous myocardial infarction and mild-to-moderate myocardial dysfunction

The prognostic meaning of myocardial viability is most important in patients with severe left ventricular dysfunction and ischaemic heart disease, but its prognostic significance in patients with previous myocardial infarction and mild-to-moderate myocardial dysfunction is uncertain. The aim of this study was to assess the prognostic value of a 201Tl single photon emission computed tomography (SPECT) rest-redistribution study in patients with previous myocardial infarction, ischaemic heart disease and mild-to-moderate myocardial dysfunction. Myocardial viability was assessed in 55 patients (50 male; mean age 58+/-9 years) by 201Tl SPECT rest-redistribution (after 4 h) scintigraphy. All patients had previous myocardial infarction (>3 months) and angiographically documented coronary artery disease, with the mean ejection fraction of 43+/-10%. Out of 55 patients, 20 were medically treated and 35 were revascularized. The follow-up period for adverse cardiac events, including death and non-fatal myocardial infarction, was 12 months. 201Tl SPECT study was positive for myocardial viability in 36 patients (65%) and negative in 19 patients (35%). Sensitivity, specificity, positive and negative predictive values for functional improvement in the follow-up period were 85%, 75%, 92% and 60%. Out of seven (13%) cardiac events in the follow-up period (four cardiac deaths and three reinfarctions), five occurred in 20 medically treated patients and two in 35 revascularized patients (25% vs 6%, P <0.05). Absence of myocardial viability was the only variable associated with adverse cardiac events (P =0.02). Survival at 12 months, as determined by using Kaplan-Meier analysis, was 56% for medically treated and non-viable patients, 80% for revascularized and non-viable patients, 91% for medically treated and viable patients, and 100% for revascularized and viable patients (P =0.0034). These findings suggest that in patients with previous myocardial infarction and mild-to-moderate myocardial dysfunction, the absence of myocardial viability as determined by the 201Tl SPECT study was the only variable associated with adverse cardiac events. The best 12 month survival was observed in revascularized viable patients, whereas the worse prognosis was found in non-viable, medically treated patients.

[Prognostic value of myocardial perfusion SPECT in multivessel coronary disease patients with left ventricular dysfunction, comparing revascularized and non-revascularized patients]

OBJECTIVE

We investigated the prognostic value of 99mTc-Tetrofosmin myocardial SPECT (99mTc-TF) in dysfunctional multivessel coronary disease patients who underwent revascularization (RV) or only medical treatment (MT).

METHODS

In 78 coronary patients with 2-3 diseased vessels and left ventricular ejection fraction (EF) <= 40% (24 10%), we have assessed the extension of the stress perfusion defect, and percent of reversibility (R) by quantification of stress-rest myocardial SPECT 99mTc-TF bull's eyes (2 days-protocol), lung/heart ratio (LH) calculated in the original stress SPECT images, and EF by equilibrium radionuclide ventriculography obtained at 24 h. A R value >= 8% was used to identify viable (V) patients. A total of 28 patients underwent RV and 50 only received MT. After a mean follow-up of 22.9 20 months (3-60), they were considered as coronary events (CE): cardiac death, non-fatal infarction and heart transplant. CE rate was 20.5% (16/78).

RESULTS

No significant differences were found in the pre-revascularization study characteristics, except a significantly higher mean R value in RV (10.6 9.5%) than in MT patients (6.4 7.8%) p: 0.03, and the main difference was that RV patients showed less CE 2/28 (7%) than the MT group 14/50 (28%) p: 0.02. The CE rate was lower in V patients who underwent RV (6%) than in V patients with MT (45%) p: 0.03, but no significant difference was obtained in non-V patients between RV (7%) and MT (16%) groups. In viable patients, the corresponding survival curves (Kaplan-Meier) showed a CE-free survival at 5 years of 79% in patients RV and of 42% in MT patients, p: 0.03, without significant difference in non-V patients.

CONCLUSIONS

Patients with viable myocardium by myocardial SPECT have a good prognosis after revascularization, and show higher risk of CE if they are only medically treated. Myocardial viability is an indispensable assessment in prognosis evaluation and, above all, in therapeutic decision making in dysfunctional multivessel coronary disease patients.

Accuracy of biphasic response, sustained improvement and worsening during dobutamine echocardiography in predicting recovery of resting myocardial dysfunction after revascularization: comparison with thallium-201 SPECT

To evaluate the accuracy of various types of wall motion response during dobutamine echocardiography (DE) in predicting functional recovery after revascularization, we studied 30 patients with stable coronary disease and left ventricular dysfunction by simultaneous DE and (201)Tl reinjection SPECT. Among 480 segments (16 segments/patient), 199 had abnormal wall motion at baseline and 167 were revascularized. The predictive value for recovery of function was 72% for a biphasic response, 61% for sustained improvement, 77% for worsening, and 27% for no change (p < 0.01 vs. each). Biphasic response had a sensitivity of 40% and specificity of 85%. Combining biphasic, sustained improvement and worsening responses, the sensitivity, specificity and accuracy were 76%, 65% and 71%, respectively. For (201)Tl SPECT, they were 90%, 65% and 78%, respectively. Thus, a biphasic response alone is of low sensitivity. Combination of biphasic, sustained improvement and worsening responses gives an accuracy rate comparable to that of (201)Tl reinjection SPECT in assessing functional recovery.