Diagnostic accuracy of supine and prone thallium-201 stress myocardial perfusion single-photon emission computed tomography to detect coronary artery disease in inferior wall of left ventricle

Diagnostic Performance of CMR, SPECT, and PET Imaging for the Identification of Coronary Artery Disease: A Meta-Analysis

Background: Myocardial perfusion imaging modalities, such as cardiac magnetic resonance (CMR), single-photon emission computed tomography (SPECT), and positron emission tomography (PET), are well-established non-invasive diagnostic methods to detect hemodynamically significant coronary artery disease (CAD). The aim of this meta-analysis is to compare CMR, SPECT, and PET in the diagnosis of CAD and to provide evidence for further research and clinical decision-making.

Methods: PubMed, Web of Science, EMBASE, and Cochrane Library were searched. Studies that used CMR, SPECT, and/or PET for the diagnosis of CAD were included. Pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, diagnostic odds ratio with their respective 95% confidence interval, and the area under the summary receiver operating characteristic (SROC) curve were calculated.

Results: A total of 203 articles were identified for inclusion in this meta-analysis. The pooled sensitivity values of CMR, SPECT, and PET were 0.86, 0.83, and 0.85, respectively. Their respective overall specificity values were 0.83, 0.77, and 0.86. Results in subgroup analysis of the performance of SPECT with ²⁰¹Tl showed the highest pooled sensitivity [0.85 (0.82, 0.88)] and specificity [0.80 (0.75, 0.83)]. ^99mTc-tetrofosmin had the lowest sensitivity [0.76 (0.67, 0.82)]. In the subgroup analysis of PET tracers, results indicated that ¹³N had the lowest pooled sensitivity [0.83 (0.74, 0.89)], and the specificity was the highest [0.91 (0.81, 0.96)].

Conclusion: Our meta-analysis indicates that CMR and PET present better diagnostic performance for the detection of CAD as compared with SPECT.

Prone Myocardial Perfusion Imaging and Breast Attenuation: A Phantom Study

Background:

Soft tissue attenuation artifacts are the most common cause of misinterpretation in myocardial perfusion Imaging (MPI). Few studies assessing the value of prone imaging in women have been published. Breast attenuation artifacts can be present in up to 40% of the MPI studies in women.

Objectives:

This study aimed at evaluating the potential impact of prone MPI on breast attenuation, with a critical analysis of activity optimization and breast size influence.

Methods:

MPI of an Anthropomorphic Torso Phantom with silicone breast prostheses and equivalent adipose tissue was compared to a standard MPI database.

Results:

A medical qualitative and semiquantitative analysis demonstrated higher uptake in the LV anterior segments in the prone position for all injected activities. An artificial myocardium lesion was diagnosable in the right segment in all images, which shows that prone positioning would not mask a true lesion and it assists the cardiologist with a more accurate analysis. These results showed that it is possible to optimize the activity to be injected by up to 55.6% when using combined supine-prone images.

Conclusion:

Prone position has a high impact on the interpretation of MPI in female patients since it reduces the breast attenuation artifacts, and optimizes the radiation protection of the patient and all staff involved in the procedure, making it more cost-effective.

Criteria for the addition of prone imaging to myocardial perfusion single-photon emission computed tomography for inferior wall

OBJECTIVE

Myocardial perfusion single-photon emission computed tomography (SPECT) is occasionally suspected to generate images that represent either ischemia or infarction for the inferior wall [right coronary artery (RCA) disease] or attenuation artifacts because of the diaphragm. We often encounter this. The application of prone imaging is advantageous in the differentiation of RCA disease because of attenuation artifacts. If decreased accumulation of radioisotopes is observed at the site with either RCA disease or attenuation artifacts, then a criterion that enables the addition of prone imaging should be implemented. Then, we evaluated sites where RCA disease and attenuation artifacts would likely appear and investigated the threshold of decreased accumulation that enables utilization of prone imaging.

PATIENTS AND METHODS

The patients in this study were divided into two groups: group A (20 patients) suspected to have attenuation artifacts because of the diaphragm and group B (14 patients) with RCA disease. Additional evaluation by prone imaging was performed in all patients. We utilized a 20-segment quantitative perfusion SPECT polar map in the supine and prone positions to compare the percentage increase in Thallium chloride (Tl) in both groups. We then investigated the percent uptake (%uptake) value of decreased accumulation in the inferior wall for the addition of prone imaging.

RESULTS

The highest %uptake was present in segments 3, 4, 5, and 10 in group A after the prone imaging. Detection of attenuation artifacts from the diaphragm was easy in segments 3, 4, 5, and 10, and we set the %uptake threshold at 62, 61, 71, and 76%, respectively, in the supine position for the addition of prone imaging.

CONCLUSION

A decrease of the %uptake in segments 3, 4, 5, and 10 after supine imaging is presumed to result from attenuation artifact or RCA disease. We established evaluation criteria for the addition of prone imaging in patients with decreased accumulation in the inferior wall during supine imaging.

Comparison Between Prone and Upright Imaging of the Inferior Wall Using 201TlCl Myocardial Perfusion SPECT

Because it suppresses attenuation artifacts from the diaphragm, prone SPECT is suitable for evaluating the cardiac inferior wall. A solid-state dedicated cardiac camera allows upright imaging, which can also be used to avoid attenuation artifacts from the diaphragm. We compared prone and upright imaging for inferior wall evaluation using ²⁰¹TlCl myocardial perfusion SPECT (MPS). Methods: The study targeted 45 patients. The prone imaging group included 23 subjects who underwent additional prone imaging because supine imaging indicated that the inferior wall had reduced uptake. The upright imaging group included 22 subjects who, in the past, had shown reduced uptake in the inferior wall during supine imaging. Using the MPS stress images and analysis software, we created a polar map showing the incorporation of the radioisotope throughout the whole of the myocardium; this polar map was then classified into 17 segments. The percentage uptake ratios of the inferior/anterior wall were calculated for the prone and upright acquisitions. These ratios were used as the ratio of percentage uptake in each segment of the anterior wall to percentage uptake in each segment of the inferior wall. In addition, 6 reviewers visually evaluated the uniformity within the inferior wall for both the prone and the upright imaging. Results: There was a significant difference in percentage uptake ratios between the prone and upright images in segments 4/1 (basal inferior/basal anterior; P < 0.05), 11/12 (mid inferolateral/mid anterolateral; P < 0.001), and 15/13 (apical inferior/apical anterior; P < 0.05). There were no significant differences between the prone and upright images in visual evaluations of uniformity within the inferior wall. Conclusion: In comparison with upright imaging, prone imaging has a higher rate of suppression of attenuation artifacts from the diaphragm. However, this difference does not seem to affect the images visually. Therefore, upright and prone imaging can be used interchangeably to evaluate the inferior wall.

A Comparison of Iterative Reconstruction and Prone Imaging in Reducing the Inferior Wall Attenuation in Tc-99m Sestamibi Myocardial Perfusion SPECT

Objective:

Prone positioning, iterative reconstruction (IR-OSEM) and electrocardiography (ECG) gating have been demonstrated to improve the specificity of myocardial perfusion SPECT (MPS) in the diagnosis of coronary artery disease.

Methods:

The gated supine and prone MPS images of 45 patients were reconstructed with both IR-OSEM [supine (SIR) and prone (PIR)] FBPs [supine (SFBP), prone (PFBP)] for comparison. Perfusion, wall motion (WM) and wall thickening were also interpreted semi-quantitatively. Two groups were generated as those with normal or abnormal findings. Segmental myocardial tracer uptake values were noted from four of the reconstructed images from 17 segment model of bullseye.

Results:

The difference between mean values and the standard deviations of the % tracer uptakes of inferior wall segments were statistically significant in all images. The normalcy rates were highest in PIR images, followed by PFBP and SIR images. The number of patients with any perfusion abnormality were 42, 12, 32, and 6, in SFBP, PFBP, SIR and PIR images, respectively. The six patients with perfusion abnormality in PIR images were re-evaluated with rest images and were diagnosed with a fixed perfusion defect. There was positive correlation between WM and either PFBP or PIR images. Sixteen patients’ WM were evaluated as abnormal while only 6 patients’ perfusions were abnormal in PIR.

Conclusion:

Prone imaging in addition to a supine perfusion SPECT improves imaging quality of the inferior wall, especially when reconstructed with iterative methods. If prone imaging can not be performed, ECG-gating can also be used as a beneficial method.

Comparative accuracy of supine-only and combined supine-prone myocardial perfusion imaging in men

BACKGROUND

Combined supine-prone myocardial perfusion imaging (CSP MPI) has been shown to reduce attenuation artifact in comparison to supine-only (SU) MPI in mixed-gender populations with varying risk for coronary artery disease (CAD), often where patients served as their own controls. However, there is limited direct comparison of these imaging strategies in men.

METHODS

934 male patients underwent CSP or SU MPI. Diagnostic certainty of interpretation was compared. Within the cohort, 116 were referred for left heart catheterization (LHC) to assess for CAD. Sensitivity, specificity, and area under the curve (AUC) were compared with additional analysis based on body mass index (BMI).

RESULTS

597 patients completed the SU protocol and 337 patients completed the CSP protocol. Equivocal studies were seen more frequently in the SU group (13%) than in the CSP group (4%, P < .001). At catheterization, the specificity for CSP MPI of 70% was higher than 40% for SU MPI (P = .032). The CSP AUC (0.80 ± 0.06) was significantly larger than SU AUC (0.57 ± 0.05, P = .004). CSP specificity was significantly higher in obese patients.

CONCLUSIONS

CSP MPI increases diagnostic certainty and improves test accuracy for CAD detection in men with CAD risk factors, especially obese patients, compared to SU MPI.

The Benefits of Prone SPECT Myocardial Perfusion Imaging in Reducing Both Artifact Defects and Patient Radiation Exposure

Background

Prone imaging has been demonstrated to minimize diaphragmatic and breast tissue attenuation.

Objectives

To determine the role of prone imaging on the reduction of unnecessary rest perfusion studies and coronary angiographies performed, thus decreasing investigation time and radiation exposure.

Methods

We examined 139 patients, 120 with an inferior wall and 19 with an anterior wall perfusion defect that might represented attenuation artifact. Post-stress images were acquired in both the supine and prone position. Coronary angiography was used as the “gold standard” for evaluating coronary artery patency. The study was terminated and rest imaging was obviated in the presence of complete improvement of the defect in the prone position. Quantitative interpretation was performed. Results were compared with clinical data and coronary angiographic findings.

Results

Prone acquisition correctly revealed defect improvement in 89 patients (89/120) with inferior wall and 12 patients (12/19) with anterior wall attenuation artifact. Quantitative analysis demonstrated statistically significant difference in the mean summed stress scores (SSS) of supine and mean SSS of prone studies in patients with disappearing inferior wall defect in the prone position and patent right coronary artery (true negative results). The mean difference between SSS in supine and in prone position was higher with disappearing than with remaining defects.

Conclusion

Technetium-99m (Tc-99m) tetrofosmin myocardial perfusion imaging with the patient in the prone position overcomes soft tissue attenuation; moreover it provides an inexpensive, accurate approach to limit the number of unnecessary rest perfusion studies and coronary angiographies performed.

Utility of left lateral supine position for myocardial perfusion single-photon emission computed tomography compared with other methods of correcting inferior wall attenuation

INTRODUCTION

Single-photon emission computed tomography (SPECT) myocardial perfusion imaging is an accepted method for reflecting the pathophysiological significance of lesions detected by coronary angiography. However, it has an inherent drawback in terms of false-positive perfusion defects for the inferior myocardial wall. To overcome this problem, different acquisition techniques have been proposed, including the computed tomographic-based attenuation correction method. In this respect, a new imaging technique, left supine lateral position SPECT myocardial perfusion imaging with technetium-99m methoxyisobutylisonitrile (Tc-99m MIBI), has been proposed to eliminate this problem and its value has been investigated in this report.

MATERIALS AND METHODS

Sixty-two patients were prospectively and randomly enrolled in this study. They underwent Tc-99m MIBI SPECT in the supine, prone, left lateral, and sitting positions after an adequate stress test on the same day.The presence and extent of defects on stress images were noted in the supine image data set for the 11 myocardial segments, which were then labeled as 1 or 0 if a defect was present or absent, respectively. This evaluation sequence was repeated in all other image data sets. When defects persisted in other scan positions it was regarded as true positive, and when they were resolved they were regarded as false positive. By this means, the percentages of resolving perfusion defects by that imaging position were calculated for each observer per positional pair under comparison.

RESULTS

From six interpretations carried out by the nuclear medicine physicians, 6×11×3=198 four-fold tables in 11 segments were analyzed for discrepancies between position pairs. In 31 of 33 discrepant interpretations, defects observed in any of the other positions were resolved in the lateral position. Only in two evaluations of one observer were the discrepancies against lateral positioning for the anterior wall. If the inferior wall was considered alone, it was clearly obvious that lateral positioning was more accurate than the other positions.Intraobserver evaluation showed the methodology to be highly reproducible.The SPECT findings were concordant with coronary angiography results in selected patients.

CONCLUSION

Visual and quantitative evaluations of the variation in inferior wall activity lead us to suggest that SPECT imaging with Tc-99m MIBI be performed in the left lateral position to allow better visualization of the inferior and septal walls in those departments not able to utilize computed tomographic attenuation correction.

Nuclear myocardial perfusion imaging using thallium-201 with a novel multifocal collimator SPECT/CT: IQ-SPECT versus conventional protocols in normal subjects

OBJECTIVE

A novel multifocal collimator, IQ-SPECT (Siemens) consists of SMARTZOOM, cardio-centric and 3D iterative SPECT reconstruction and makes it possible to perform MPI scans in a short time. The aims are to delineate the normal uptake in thallium-201 ((201)Tl) SPECT in each acquisition method and to compare the distribution between new and conventional protocol, especially in patients with normal imaging.

METHODS

Forty patients (eight women, mean age of 75 years) who underwent myocardial perfusion imaging were included in the study. All patients underwent one-day protocol perfusion scan after an adenosine-stress test and at rest after administering (201)Tl and showed normal results. Acquisition was performed on a Symbia T6 equipped with a conventional dual-headed gamma camera system (Siemens ECAM) and with a multifocal SMARTZOOM collimator. Imaging was performed with a conventional system followed by IQ-SPECT/computed tomography (CT). Reconstruction was performed with or without X-ray CT-derived attenuation correction (AC). Two nuclear physicians blinded to clinical information interpreted all myocardial perfusion images. A semi-quantitative myocardial perfusion was analyzed by a 17-segment model with a 5-point visual scoring. The uptake of each segment was measured and left ventricular functions were analyzed by QPS software.

RESULTS

IQ-SPECT provided good or excellent image quality. The quality of IQ-SPECT images without AC was similar to those of conventional LEHR study. Mid-inferior defect score (0.3 ± 0.5) in the conventional LEHR study was increased significantly in IQ-SPECT with AC (0 ± 0). IQ-SPECT with AC improved the mid-inferior decreased perfusion shown in conventional images. The apical tracer count in IQ-SPECT with AC was decreased compared to that in LEHR (0.1 ± 0.3 vs. 0.5 ± 0.7, p < 0.05). The left ventricular ejection fraction from IQ-SPECT was significantly higher than that from the LEHR collimator (p = 0.0009).

CONCLUSION

The images of IQ-SPECT acquired in a short time are equivalent to that of conventional LEHR. The results indicated that the IQ-SPECT system with AC is capable of correcting inferior artifacts with high image quality.

A second look with prone SPECT myocardial perfusion imaging reduces the need for angiography in patients at low risk for cardiac death or MI

BACKGROUND

Correction for soft tissue signal attenuation can improve the diagnostic accuracy of single-photon emission computed tomography myocardial perfusion imaging (SPECT-MPI). The aim of this study was to correlate SPECT-MPI findings with clinical outcomes in patients who underwent stress imaging in the supine position, who also underwent "second look" stress imaging in the prone position.

METHODS

Patients without perfusion abnormalities were considered Normal (N = 270). Those with apparent supine stress perfusion abnormalities which all resolved during prone imaging formed the Normal-Prone group (N = 309). Patients with matched perfusion abnormalities during both supine and prone stress imaging were considered Abnormal (N = 169).

RESULTS

During follow-up (187 ± 96 days), utilization rates for invasive coronary angiography were similar for Normal vs Normal-Prone patients (3.5% vs 3.8%; P = NS), but were significantly higher in Abnormal patients (42.4%, P < .0001). Coronary revascularization occurred in 0.78%, 0.64%, and 17.7% of Normal, Normal-Prone, and Abnormal patients, respectively (P < .001). Cardiac death or myocardial infarction occurred in 2.2%, 2.3%, and 6.3% of Normal, Normal-Prone, and Abnormal patients, respectively (P = .02).

CONCLUSIONS

Second look SPECT-MPI identifies patients at low risk for death or myocardial infarction, who infrequently require invasive coronary angiography.

Soft tissue attenuation patterns in stress myocardial perfusion SPECT images: a comparison between supine and upright acquisition systems

BACKGROUND

Soft tissue attenuation patterns and their interaction with body habitus and gender in Single Photon Emission Computed Tomography (SPECT)-myocardial perfusion imaging (MPI) of upright patient-position acquisition systems are not well described.

METHODS

In a retrospective cross-sectional study, we compared the prevalence and patterns of soft tissue attenuation in two groups of normal SPECT-MPI studies acquired by supine (n = 263) vs upright (n = 212) acquisition systems.

RESULTS

Attenuation patterns observed in the study population were: anterior (22.3%), inferior (51.6%) and lateral (18.1%). Anterior attenuation was significantly less in those imaged upright (6.1% vs 35.4%), P < .001; particularly among women (9.5% vs 50.7%), P < .001. Inferior attenuation was more common among women imaged upright (49.5% vs 13.5%), P < .001; but was not affected by imaging position among men. Lateral attenuation was more prevalent in the upright group (24.1% vs 13.3%), P = .002; and had a strong association with female gender (P < .001) and BMI ≥ 30 (P < .001).

CONCLUSIONS

Upright SPECT-MPI acquisition is associated with a unique attenuation pattern which is vastly different than the supine position. Female gender strongly impacted this attenuation pattern, particularly obese women. Our study is the first to describe, in details, the attenuation patterns with upright imaging and is critical for the accurate interpretation of SPECT-MPI acquired with upright systems.