Is computed tomography attenuation correction more efficient than gated single photon emission computed tomography analysis in improving the diagnostic performance of myocardial perfusion imaging in patients with low prevalence of ischemic heart disease?

Comparison of the Diagnostic Performance of Myocardial Perfusion Scintigraphy with and Without Attenuation Correction

Objectives:

Myocardial perfusion scintigraphy (MPS) is an important diagnostic test for detecting of coronary artery stenosis (CAS); however, tissue attenuation can lead to a difference in accuracy. We evaluated the diagnostic accuracy of attenuation-corrected (AC) and non-attenuation-corrected (NC) MPS for the detection of CAS.

Methods:

We retrospectively recruited patients who underwent invasive coronary angiography within 10 months after Tc-99m sestamibi MPS. The AC and NC perfusion images were analyzed separately, and each myocardial segment was scored based on relative uptake from 0 to 4. The summed stress score (SSS), summed rest score (SRS), and summed difference score (SDS) were calculated. The diagnostic performances were analyzed using the area under the curve (AUC) of the receiver operating characteristic curve.

Results:

From 117 patients, significant coronary stenosis was present in 66 patients (56%). The SSS and SRS obtained from NC-images were higher than those from AC, supporting the presence of attenuation artifacts in NC images. The AUC of SSS and SDS were significantly higher than those of SRS in both AC- and NC-images, but no significant difference was found between the AUC of SSS, and those of SDS. The optimal cut-offs were >12 for AC-SSS, >15 for NC-SSS, >4 for AC-SDS and >3 for NC-SDS. There was no statistically significant difference in the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy among AC-SSS, NC-SSS, AC-SDS, and NC-SDS.

Conclusion:

NC-based Tc-99m-sestamibi MPS promised comparable accuracy to AC images by using different cut-off values for diagnosis.

CT Attenuation correction and its impact on image quality of myocardial perfusion imaging in coronary artery disease: A systematic review

Myocardial perfusion imaging is a non-invasive procedure that plays an integral role in the diagnosis and management of coronary artery disease. With the routine use of computerised tomography attenuation correction (CTAC) in myocardial perfusion imaging still under debate, the aim of this review was to determine the impact of CTAC on image quality in myocardial perfusion imaging. Medline, Embase and CINAHL were searched from the earliest available time until August 2019. Methodological quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies version 2. Details pertaining to image quality and diagnostic accuracy were analysed, and results summarised descriptively. Three studies with 'unclear' risk of bias and low applicability concerns (1002 participants) from a yield of 2725 articles were identified. Two studies demonstrated an increase in image quality, and one study found no difference in image quality when using CTAC compared to no attenuation correction. Benefits of CTAC for improving image quality remain unclear. Given the potential exposure risk with the addition of CTAC, patient and clinician factors should inform decision making for use of CTAC in myocardial perfusion imaging for coronary artery disease.

Improved diagnostic accuracy of thallium-201 myocardial perfusion single-photon emission computed tomography with CT attenuation correction

BACKGROUND

The benefits of attenuation correction (AC) in technetium-99m myocardial perfusion imaging (MPI) have been well established. However, the value of thallium (Tl-201) AC and routine computed tomography AC (CTAC) were less well established. The aims of this study were to evaluate the diagnostic performance of thallium (Tl-201) MPI with additional CTAC and to determine which participants would benefit most.

METHODS AND RESULTS

A total of 108 consecutive patients who underwent Tl-201 MPI and received coronary angiography within 3 months were enrolled. Diagnostic performance was determined by sensitivity, specificity, and receiver operating characteristic curve analysis. Subgroup analyses were performed using gender and obesity. CTAC improved the area under the curve (0.84 vs. 0.77, P = 0.037 at patient level), primarily due to a significant improvement in specificity (0.78 vs. 0.57, P = 0.013) and no significant difference in sensitivity (0.79 vs. 0.82, P = 0.75). In subgroup analysis, CTAC was most helpful in obese subjects, men, and especially right coronary artery lesions.

CONCLUSIONS

CTAC significantly improved diagnostic performance primarily by increasing the specificity, and the improvements were significantly greater in obese patients and male patients. These findings suggest that CTAC should be applied to Tl-201 MPI as routine clinical practice.

Gated single-photon emission computed tomography myocardial perfusion imaging is superior to computed tomography attenuation correction in discriminating myocardial infarction from attenuation artifacts in men and right coronary artery disease

BACKGROUND

In single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) studies, attenuation artifacts frequently cause false positives, which can be partially overcome by computed tomography attenuation correction (CT-AC) or gated acquisition [gated myocardial perfusion imaging (GMPI)]. The purpose of this study is to evaluate their relative diagnostic performances for coronary artery disease (CAD).

PATIENTS AND METHODS

We enrolled 181 patients who underwent gated SPECT with CT-AC in this study. Two observers who were blinded to the clinical data interpreted the GMPI and CT-AC images. Coronary angiography was considered as the reference standard. The diagnostic efficacy was evaluated based on sex, BMI, and individual coronary arteries.

RESULTS

The diagnostic accuracy of GMPI was higher than that of nonattenuation correction overall, as well as for men, overweight individuals, and right CAD (P<0.05). Compared with CT-AC, GMPI overall had a higher specificity (96.3 vs. 86.9%, P=0.014) but the same sensitivity, achieving an increased accuracy and area under the curve (AUC, P>0.05). For diagnosing right CAD, GMPI had a higher diagnostic efficacy (AUC: 0.733 vs. 0.596, P<0.001) because of its higher sensitivity (52.0 vs. 26.0%, P=0.008); for men, the diagnostic efficacy of GMPI was significantly higher than that of CT-AC (AUC: 0.754 vs. 0.681, P=0.038).

CONCLUSION

Both CT-AC and GMPI led to an increased diagnostic efficacy compared with nonattenuation correction in differentiating attenuation artifacts from fixed perfusion defects. These improvements were, however, more obvious for GMPI than for CT-AC, especially in men and right CAD.

Diagnostic value of thallium-201 myocardial perfusion IQ-SPECT without and with computed tomography-based attenuation correction to predict clinically significant and insignificant fractional flow reserve: A single-center prospective study

The aim of this study was to clarify the predictive value of fractional flow reserve (FFR) determined by myocardial perfusion imaging (MPI) using thallium (Tl)-201 IQ-SPECT without and with computed tomography-based attenuation correction (CT-AC) for patients with stable coronary artery disease (CAD).We assessed 212 angiographically identified diseased vessels using adenosine-stress Tl-201 MPI-IQ-SPECT/CT in 84 consecutive, prospectively identified patients with stable CAD. We compared the FFR in 136 of the 212 diseased vessels using visual semiquantitative interpretations of corresponding territories on MPI-IQ-SPECT images without and with CT-AC.FFR inversely correlated most accurately with regional summed difference scores (rSDS) in images without and with CT-AC (r = -0.584 and r = -0.568, respectively, both P < .001). Receiver-operating characteristics analyses using rSDS revealed an optimal FFR cut-off of <0.80 without and with CT-AC. Although the diagnostic accuracy of FFR <0.80 did not significantly differ, FFR ≥0.82 was significantly more accurate with, than without CT-AC. Regions with rSDS ≥2 without or with CT-AC predicted FFR <0.80, and those with rSDS ≤1 without and with CT-AC predicted FFR ≥0.81, with 73% and 83% sensitivity, 84% and 67% specificity, and 79% and 75% accuracy, respectively.Although limited by the sample size and the single-center design, these findings showed that the IQ-SPECT system can predict FFR at an optimal cut-off of <0.80, and we propose a novel application of CT-AC to MPI-IQ-SPECT for predicting clinically significant and insignificant FFR even in nonobese patients.