Assessment of tumor blood flow in breast tumors with T1‐dynamic contrast‐enhanced MR Imaging: Impact of dose reduction and the use of a prebolus technique on diagnostic efficacy

Purpose:

To prospectively evaluate whether dose reduction and the application of a prebolus technique can effectively alleviate signal saturation effects in T1 dynamic contrast enhanced (T1‐DCE) magnetic resonance imaging (MRI) data in breast tumors and lead to increased diagnostic efficacy of the regional tumor blood flow (TBF) values obtained with deconvolution of T1‐DCE MRI data.

Materials and Methods:

After obtaining informed consent, 23 women (32–80 years) with histologically proven breast tumors underwent MR mammography that included a whole‐breast T1 DCE sequence. In the slice where the tumor enhanced maximally, a prebolus protocol was applied. One mL of Gd‐DTPA solution at 2 mL/s was injected at the beginning of a dynamic axial single slice inversion‐prepared turbo field echo acquisition. At the 400th dynamic, a high dose of either 20 mL (15 patients) or 10 mL (8 patients) of contrast agent was injected at 2 mL/s and a further 400 dynamics were acquired. From the aortic prebolus curve an arterial input function (AIF) was reconstructed by time‐shifting and adding the prebolus data. The relative enhancement time course from the tumor region of interest was deconvolved with the reconstructed AIF to generate the impulse response function, the maximum of which yielded the TBF. The institutional ethical committee approved the study.

Results:

Reducing the contrast dose by a factor of 2 led to an increase in diagnostic contrast for the TBF values of malignant and benign tumors by a factor of slightly more than 2. Addition of the prebolus technique improved this further by 45%. receiver operating characteristic analysis showed a significant increase of diagnostic yield related to the combined use of a prebolus and minimal dose.

Conclusion:

Using a prebolus approach provides an estimate of the unsaturated AIF, while reduction of the high‐dose bolus minimizes possible saturation effects in the tumor time course. J. Magn. Reson. Imaging 2010;31:556–561. ©2010 Wiley‐Liss, Inc.     

Quantitative contrast‐enhanced perfusion measurements of the human lung using the prebolus approach

Purpose

To investigate dynamic contrast‐enhanced MRI (DCE‐MRI) for quantification of pulmonary blood flow (PBF) and blood volume (PBV) using the prebolus approach and to compare the results to the global lung perfusion (GLP).

Materials and Methods

Eleven volunteers were examined by applying different contrast agent doses (0.5, 1.0, 2.0, and 3.0 mL gadolinium diethylene triamine pentaacetic acid [Gd‐DTPA]), using a saturation‐recovery (SR) true fast imaging with steady precession (TrueFISP) sequence. PBF and PBV were determined for single bolus and prebolus. Region of interest (ROI) evaluation was performed and parameter maps were calculated. Additionally, cardiac output (CO) and lung volume were determined and GLP was calculated as a contrast agent–independent reference value.

Results

The prebolus results showed good agreement with low‐dose single‐bolus and GLP: PBF (mean ± SD in units of mL/minute/100 mL) = single bolus 190 ± 73 (0.5‐mL dose) and 193 ± 63 (1.0‐mL dose); prebolus 192 ± 70 (1.0–2.0‐mL dose) and 165 ± 52 (1.0–3.0‐mL dose); GLP (mL/minute/100 mL) = 187 ± 34. Higher single‐bolus resulted in overestimated values due to arterial input function (AIF) saturation.

Conclusion

The prebolus approach enables independent determination of appropriate doses for AIF and tissue signal. Using this technique, the signal‐to‐noise ratio (SNR) from lung parenchyma can be increased, resulting in improved PBF and PBV quantification, which is especially useful for the generation of parameter maps. J. Magn. Reson. Imaging 2009;30:104–111. © 2009 Wiley‐Liss, Inc.     

Prebolus quantitative MR heart perfusion imaging.

The purpose of this study was to present the prebolus technique for quantitative multislice myocardial perfusion imaging. In quantitative MR perfusion studies the maximum contrast agent dose is limited by the requirement to determine the arterial input function (AIF). The prebolus technique consists of two consecutive contrast agent administrations. The AIF is determined from a first low-dose bolus, while a second, high-dose bolus allows the measurement of the myocardium with improved signal increase. The results of the prebolus technique using a multislice saturation recovery trueFISP sequence in healthy volunteers are presented. In comparison to a standard dose of 3 ml Gd-DTPA, perfusion values are maintained while the signal increase in the concentration time courses was considerably improved, accompanied by reduced standard deviations of the obtained perfusion values (0.72 +/- 0.13 ml/g/min for 1 ml/8 ml and 0.67 +/- 0.10 ml/g/min for 1 ml/12 ml Gd-DTPA, respectively).     

Electrocardiographic changes during vasodilator SPECT myocardial perfusion imaging: Does it affect diagnosis or prognosis?

Background

Significance of electrocardiographic (ECG) changes during vasodilator stress myocardial perfusion imaging (MPI) is controversial. We examined the diagnostic and prognostic significance of ECG changes during vasodilator single photon emission computerized tomography (SPECT) MPI.

Methods

We studied consecutive patients who underwent vasodilator SPECT MPI from 1995 to 2009. Patients with baseline ECG abnormalities, previous history of coronary artery bypass graft surgery or myocardial infarction (MI) were excluded. Significant coronary artery disease (CAD) was defined as >70% stenosis of any vessel or ??50% stenosis of left main. Mean follow-up was 2.4?±?1.5?years for cardiac events (cardiac death and non-fatal MI).

Results

Of patients in the diagnostic cohort, ST depression was associated with increased incidence of CAD with abnormal (P?=?.020 and P?<.001) but not in those with normal perfusion (P?=?.342). Of 3,566 patients with follow-up in the prognostic cohort, including 130 (5.0%) with ST depression and normal perfusion, the presence of ST depression ??1?mm did not affect the outcomes in any summed stress score category.

Conclusions

ST depression ??1?mm during vasodilator SPECT MPI is associated with CAD in patients with abnormal perfusion, but provides no additional risk stratification beyond concomitant perfusion imaging, including those with normal studies.     

Automated quantitative Rb-82 3D PET/CT myocardial perfusion imaging: Normal limits and correlation with invasive coronary angiography

Background

We aimed to characterize normal limits and to determine the diagnostic accuracy for an automated quantification of 3D 82-Rubidium (Rb-82) PET/CT myocardial perfusion imaging (MPI).

Methods

We studied 125 consecutive patients undergoing Rb-82 PET/CT MPI, including patients with suspected coronary artery disease (CAD) and invasive coronary angiography, and 42 patients with a low likelihood (LLk) of CAD. Normal limits for perfusion and function were derived from LLk patients. QPET software was used to quantify perfusion abnormality at rest and stress expressed as total perfusion deficit (TPD).

Results

Relative perfusion databases did not differ in any of the 17 segments between males and females. The areas under the receiver operating characteristic curve for detection of CAD were 0.86 for identification of ??50% and ??70% stenosis. The sensitivity/specificity was 86%/86% for detecting ??50% stenosis and 93%/77% for ??70% stenosis, respectively. In regard to normal limits, mean rest and stress left ventricular ejection fraction (LVEF) were 67%?±?10% and 75%?±?9%, respectively. Mean transient ischemic dilation ratio was 1.06?±?0.14 and mean increase in LVEF with stress was 7.4%?±?6.1% (95th percentile of 0%).

Conclusion

Normal limits have been established for 3D Rb-82 PET/CT analysis with QPET software. Fully automated quantification of myocardial perfusion PET data shows high diagnostic accuracy for detecting obstructive CAD.     

Correction of arterial input function in dynamic contrast-enhanced MRI of the liver

Purpose:

To develop a postprocessing method to correct saturation of arterial input function (AIF) in T1‐weighted dynamic contrast‐enhanced magnetic resonance imaging (DCE‐MRI) for quantification of hepatic perfusion.

Materials and Methods:

The saturated AIF is corrected by parameterizing the first pass of the AIF as a smooth function with a single peak and minimizing a least‐squares error in fitting the liver DCE‐MRI data to a dual‐input single‐compartment model. Sensitivities of the method to the degree of saturation in the AIF first‐pass peak and the image contrast‐to‐noise ratio were assessed. The method was also evaluated by correlating portal venous perfusion with an independent overall liver function measurement.

Results:

The proposed method corrects the distorted AIF with a saturation ratio up to 0.45. The corrected AIF improved hepatic arterial perfusion by ?23.4% and portal venous perfusion by 26.9% in a study of 12 patients with liver cancers. The correlation between the mean voxelwise portal venous perfusion and overall liver function measurement was improved by using the corrected AIFs (R² = 0.67) compared with the saturated AIFs (R² = 0.39).

Conclusion:

The method is robust for correcting AIF distortion and has the potential to improve quantification of hepatic perfusion for assessment of liver tissue response to treatment in patients with hepatic cancers. J. Magn. Reson. Imaging 2012;36:411–421. © 2012 Wiley Periodicals, Inc.

     

Quantitative first‐pass perfusion MRI of the mouse myocardium

In this article, we present a first‐pass perfusion imaging protocol to determine quantitative regional perfusion values (in mL min^?1 g^?1) of the mouse myocardium. Perfusion was quantified using a Fermi‐constrained deconvolution of the myocardial tissue response with the arterial input function. A dual‐bolus approach was implemented. Experimental evidence is presented for the linearity of signal intensity in the left‐ventricular lumen during the prebolus (r = 0.99, P < 0.001) and in the myocardium during the full‐bolus injection (r = 0.99, P < 0.01) as function of Gd(DTPA)^2? injection concentration used. The prebolus was used to reconstruct a nonsaturated arterial input function. Regional perfusion values proved repeatable in a cohort of nine healthy C57BL/6 mice. The perfusion values over two measurements with a 1‐week interval were 7.3 ± 0.9 and 7.2 ± 0.6 mL min^?1 g^?1, respectively. No effects of time (P > 0.05) and myocardial region (P > 0.05) were observed. The between‐session coefficient of variation was only 6%, whereas the inter‐animal coefficient of variation was 11 and 8% for the separate experiments. We expect that the first‐pass perfusion method here presented will be useful in preclinical studies of myocardial perfusion deficits and valuable to assess the impact of pro‐angiogenic therapy after myocardial infarction. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.     

Nuclear myocardial perfusion imaging with a novel cadmium-zinc-telluride detector SPECT/CT device: first validation versus invasive coronary angiography

Purpose  

We evaluated the diagnostic accuracy of attenuation corrected nuclear myocardial perfusion imaging (MPI) with a novel hybrid single photon emission computed tomography (SPECT)/CT device consisting of an ultrafast dedicated cardiac gamma camera with cadmium-zinc-telluride (CZT) solid-state semiconductor detectors integrated onto a multislice CT scanner to detect coronary artery disease (CAD). Invasive coronary angiography served as the standard of reference.     

Incremental value of combining 64-slice computed tomography angiography with stress nuclear myocardial perfusion imaging to improve noninvasive detection of coronary artery disease

Background  

To compare the accuracy of combined 64-slice computed tomography angiography (CTA) and stress nuclear myocardial perfusion imaging (MPI) in the noninvasive detection of coronary artery disease (CAD) with that of 64-slice CTA alone.     

Diagnostic performance of stress myocardial perfusion imaging for coronary artery disease: a systematic review and meta-analysis

Objectives

To determine and compare the diagnostic performance of stress myocardial perfusion imaging (MPI) for the diagnosis of obstructive coronary artery disease (CAD), using conventional coronary angiography (CCA) as the reference standard.

Methods

We searched Medline and Embase for literature that evaluated stress MPI for the diagnosis of obstructive CAD using magnetic resonance imaging (MRI), contrast-enhanced echocardiography (ECHO), single-photon emission computed tomography (SPECT) and positron emission tomography (PET).

Results

All pooled analyses were based on random effects models. Articles on MRI yielded a total of 2,970 patients from 28 studies, articles on ECHO yielded a sample size of 795 from 10 studies, articles on SPECT yielded 1,323 from 13 studies. For CAD defined as either at least 50?%, at least 70?% or at least 75?% lumen diameter reduction on CCA, the natural logarithms of the diagnostic odds ratio (lnDOR) for MRI (3.63; 95?% CI 3.26–4.00) was significantly higher compared to that of SPECT (2.76; 95?% CI 2.28–3.25; P?=?0.006) and that of ECHO (2.83; 95?% CI 2.29–3.37; P?=?0.02). There was no significant difference between the lnDOR of SPECT and ECHO (P?=?0.52).

Conclusion

Our results suggest that MRI is superior for the diagnosis of obstructive CAD compared with ECHO and SPECT. ECHO and SPECT demonstrated similar diagnostic performance.

Key Points

? MRI can assess myocardial perfusion. ? MR perfusion diagnoses coronary artery disease better than echocardiography or SPECT. ? Echocardiography and SPECT have similar diagnostic performance. ? MRI can save coronary artery disease patients from more invasive tests. ? MRI and SPECT show evidence of publication bias, implying possible overestimation.     

The clinical value of single photon emission computed tomography myocardial perfusion imaging in cardiac risk stratification of very elderly patients (≥80 years) with suspected coronary artery disease

Background  

The role of single photon emission computed tomography myocardial perfusion imaging (SPECT MPI) in cardiac evaluation of the very elderly patients is unclear. We investigated the clinical value of SPECT MPI in very elderly patients (≥80 years) with suspected coronary artery disease (CAD) as well as in comparison to younger patients.     

Comprehensive MR evaluation of renal disease: Added clinical value of quantified renal perfusion values over single MR angiography

Purpose:

To evaluate the diagnostic accuracy of quantified renal perfusion parameters in identifying and differentiating renovascular from renal parenchymal disease.

Materials and Methods:

In all, 27 patients underwent renal perfusion measurements on a 3.0 T magnetic resonance imaging (MRI) system. Imaging was performed with a saturation recovery TurboFLASH sequence (TR/TE 177/0.93 msec, flip angle 12°, 5 slices/sec). All patients also underwent high‐resolution MR angiography (MRA) (TR/TE 3.1/1.09, flip angle 23°, spatial resolution 0.9 × 0.8 × 0.9 mm³). MR perfusion measurements were analyzed with a two‐compartment model, quantifying the plasma flow (F_P)—a characteristic renal first‐pass perfusion parameter. A receiver‐operator characteristic analysis was used to determine the optimal threshold value for distinguishing normal and abnormal plasma flow values. Utilizing this cutoff, sensitivity and specificity of solitary MR perfusion measurements, MRA, and a diagnostic strategy combining the two were evaluated.

Results:

Quantified MR perfusion values yielded a sensitivity of 100% and a specificity of 85% utilizing the optimal plasma flow threshold value of 150 mL/100 mL/min, whereas single MRA achieved a sensitivity of 51.9% and a specificity of 90%. Combining both methods enabled improved detection of renovascular and renoparenchymal disease with a sensitivity of 96.3% and specificity of 90%.

Conclusion:

In distinction to MRA, quantified MR perfusion measurements allow for the detection of pure renal parenchymal disorders. The combination of MRA with these perfusion measurements suggests an algorithm by which parenchymal and renovascular diseases may be reliably distinguished and the hemodynamic significance of the latter reliably determined. J. Magn. Reson. Imaging 2010;31:125–133. © 2009 Wiley‐Liss, Inc.     

Does quantification of myocardial flow reserve using rubidium-82 positron emission tomography facilitate detection of multivessel coronary artery disease?

Background

Relative myocardial perfusion imaging (MPI) is the standard imaging approach for the diagnosis and prognostic work-up of coronary artery disease (CAD). However, this technique may underestimate the extent of disease in patients with 3-vessel CAD. Positron emission tomography (PET) is also able to quantify myocardial blood flow. Rubidium-82 (⁸²Rb) is a valid PET tracer alternative in centers that lack a cyclotron. The aim of this study was to assess whether assessment of myocardial flow reserve (MFR) measured with ⁸²Rb PET is an independent predictor of severe obstructive 3-vessel CAD.

Methods

We enrolled a cohort of 120 consecutive patients referred to a dipyridamole ⁸²Rb PET MPI for evaluation of ischemia neither with prior coronary artery bypass graft nor with recent percutaneous coronary intervention that also underwent coronary angiogram within 6?months of the PET study. Patients with and without 3-vessel CAD were compared.

Results

Among patients with severe 3-vessel CAD, MFR was globally reduced (<2) in 88% (22/25). On the adjusted logistic Cox model, MFR was an independent predictor of 3-vessel CAD [.5 unit decrease, HR: 2.1, 95% CI (1.2-3.8); P?=?.015]. The incremental value of ⁸²Rb MFR over the SSS was also shown by comparing the adjusted SSS models with and without ⁸²Rb MFR (P?=?.005).

Conclusion

⁸²Rb MFR is an independent predictor of 3-vessel CAD and provided added value to relative MPI. Clinical integration of this approach should be considered to enhance detection and risk assessment of patients with known or suspected CAD.     

Prevalence,location, and extent of significant coronary artery disease in patients with normal myocardial perfusion imaging

Background

False-negative myocardial perfusion imaging (MPI) can by due to left main (LM) or three-vessel disease causing “balanced ischemia”. However, so far prevalence of LM or three-vessel-disease in patients with normal MPI is unclear. We assessed prevalence, location, and extent of significant coronary artery disease (CAD) in patients with normal MPI.

Methods

Between 2006 and 2010, 256 patients with normal MPI who had invasive angiography because of persisting or worsening of the same initial symptoms were studied. Significant CAD was defined as stenosis > 70% or LM > 50%.

Results

A total of 93 patients (36%) had significant CAD. Significant CAD was observed more frequently in males, higher age and those with typical angina complaints. Significant LM disease was present in 7%, three-vessel disease in 10%, two-vessel disease in 22%, and single vessel disease (not left main) in 61%. In those with single vessel disease, the location was the LAD in 40%, the RCA in 30%, and the LCX in 30%.

Conclusions

In selected patients with normal MPI, one-third had significant CAD. The majority of these patients had single vessel disease (not left main). LM or three vessel disease, causing “balanced ischemia”, is a less common cause of false-negative MPI.     

The relationship between stress-induced myocardial ischemia and coronary artery atherosclerosis measured by hybrid SPECT/CT camera

Objective  

The coronary artery calcium (CAC) score and myocardial perfusion imaging can now be detected simultaneously using a hybrid SPECT/CT camera. However, there has been little evaluation on the relationship between stress-induced ischemia and coronary artery calcification in a Japanese population. The aim of this study was to investigate the relationship between these parameters and to elucidate the diagnostic value of the CAC score as an adjunct to myocardial perfusion imaging (MPI) for the assessment of coronary artery disease (CAD) in an intermediate-risk population.     

Improvement in automated quantitation of myocardial perfusion abnormality by using iterative reconstruction image in combination with resolution recovery,attenuation and scatter corrections for the detection of coronary artery disease

Objective

An iterative reconstruction method in combination with resolution recovery, attenuation and scatter corrections (IR-RASC) can improve image quality. It, however, is undetermined whether this technique can improve the detection of coronary artery disease (CAD) when automated quantitative analysis is used. This study evaluated diagnostic values of IR-RASC in combination with automated quantitative analysis in stress myocardial perfusion imaging (MPI) in the CAD detection.

Methods

This study enrolled consecutive 64 patients (mean age 66.2 ± 17.3 years, 39 males) who had undergone both ^99mTc-labeled tetrofosmin stress MPI and coronary angiography within 3 months. Stress MPI abnormalities quantified as summed stress score (SSS), summed rest score (SRS) and summed difference score (SDS) by Heart Risk View-S (HRV-S) and Quantitative Perfusion SPECT (QPS) softwares using IR-RASC images were compared with those by using conventional filtered back-projection method (FBP) images and angiographic findings.

Results

Based on expert visual assessment, SSS and SRS by HRV-S/QPS softwares with IR-RASC were significantly lower than those by HRV-S/QPS softwares with FBP at mid- and basal left ventricular segments. Receiver-operating characteristics analysis showed that areas under the curve assessed by HRV-S (0.687) and QPS (0.678) with IR-RASC were nearly identical to those (0.717–0.724) by expert assessment with FBP, and were significantly (P < 0.05) greater than those by HRV-S (0.505) and QPS (0.522) with FBP. When HRV-S was used, the specificity and diagnostic accuracy of IR-RASC in the CAD detection were significantly greater than those of FBP: 90.3 versus 51.6%, P < 0.0001 and 79.7 versus 54.7%, P = 0.0027, respectively. Likewise, when QPS was used, the specificity and diagnostic accuracy of IR-RASC in the CAD detection were significantly greater than those of FBP: 80.6 versus 41.9%, P < 0.0001, and 78.1 versus 51.6%, P = 0.0018, respectively. There, however, were no significant differences in sensitivity between IR-RASC and FBP images.

Conclusions

IR-RASC can improve diagnostic accuracy of the CAD detection using an automated scoring system compared to FBP, by reducing false positivity due to artefactual appearance.

     

Computer-aided diagnosis system outperforms scoring analysis in myocardial perfusion imaging

Background

The aim of this myocardial perfusion imaging (MPI) study was to compare the diagnostic performance of two computer-aided diagnosis (CAD) systems, EXINI Heart^TM (EXINI), and PERFEX^TM (PERFEX) Emory Cardiac Toolbox (ECT), and the summed stress score (SSS) values from both software packages.

Methods

We studied 1,052 consecutive patients who underwent 2-day stress/rest ^99mTc-sestamibi MPI studies. The reference standard classifications for the MPI studies were obtained from three experienced physicians who separately classified all cases regarding the presence or absence of ischemia and/or infarction. Automatic processing was carried out using EXINI and PERFEX to obtain CAD results and SSS values based on the 17-segment model.

Results

The three experts’ classifications showed ischemia in 257 patients and abnormal studies, i.e., either ischemia or infarction or both, in 318 patients. Accuracy was significantly higher in EXINI than in PERFEX, regarding both the detection of ischemia (87.4 vs 77.6%; P < 0.0001) and the detection of abnormal studies (91.6 vs 67.9%; P < 0.0001). EXINI’s CAD system showed a higher specificity than its SSS values (86.8 vs 73.6%; P < 0.0001) at the same level of sensitivity.

Conclusions

EXINI demonstrated greater diagnostic accuracy for detection of ischemia and abnormal studies than did PERFEX. EXINI CAD also outperformed its SSS analysis.     

Diagnostic and clinical benefit of combined coronary calcium and perfusion assessment in patients undergoing PET/CT myocardial perfusion stress imaging

Background  

A limitation of stress myocardial perfusion imaging (MPI) is the inability to detect non-obstructive coronary artery disease (CAD). One advantage of MPI with a hybrid CT device is the ability to obtain same-setting measurement of the coronary artery calcium score (CACS).     

Comparison of intravascular and extracellular contrast media for absolute quantification of myocardial rest-perfusion using high-resolution MRI

Purpose:

To use the contrast agent gadofosveset for absolute quantification of myocardial perfusion and compare it with gadobenate dimeglumine (Gd‐BOPTA) using a high‐resolution generalized autocalibrating partially parallel acquisition (GRAPPA) sequence.

Materials and Methods:

Ten healthy volunteers were examined twice at two different dates with a first‐pass perfusion examination at rest using prebolus technique. We used a 1.5 T scanner and a 32 channel heart‐array coil with a steady‐state free precession (SSFP) true fast imaging with steady state precession (trueFISP) GRAPPA sequence (acceleration‐factor 3). Manual delineation of the myocardial contours was performed and absolute quantification was performed after baseline and contamination correction. At the first appointment, 1cc/4cc of the extracellular contrast agent Gd‐BOPTA were administered, on the second date, 1cc/4cc of the blood pool contrast agent (CA) gadofosveset. At each date the examination was repeated after a 15‐minute time interval.

Results:

Using gadofosveset perfusion the value (in cc/g/min) at rest was 0.66 ± 0.25 (mean ± standard deviation) for the first, and 0.55 ± 0.24 for the second CA application; for Gd‐BOPTA it was 0.62 ± 0.25 and 0.45 ± 0.23. No significant difference was found between the acquired perfusion values. The apparent mean residence time in the myocardium was 23 seconds for gadofosveset and 19.5 seconds for Gd‐BOPTA. Neither signal‐to‐noise ratio (SNR) nor subjectively rated image contrast showed a significant difference.

Conclusion:

The application of gadofosveset for an absolute quantification of myocardial perfusion is possible. Yet the acquired perfusion values show no significant differences to those determined with Gd‐BOPTA, maintained the same SNR and comparable perfusion values, and did not picture the expected concentration time‐course for an intravasal CA in the first pass. J. Magn. Reson. Imaging 2011;33:1047–1051. © 2011 Wiley‐Liss, Inc.     

The significance of transient ischemic dilation in the setting of otherwise normal SPECT radionuclide myocardial perfusion images

Background

Transient ischemic dilation (TID) in the setting of an abnormal SPECT radionuclide myocardial perfusion imaging (MPI) study is considered a marker of severe and extensive coronary artery disease (CAD). However, the clinical significance of TID and its association with CAD in patients with an otherwise normal MPI study is unclear.

Methods

From a database of patients who underwent MPI over a 9-year period, 96 without known cardiac history who had normal image perfusion patterns, and who underwent coronary angiography within 6 months, were identified. TID quantitative values were derived. To adjust for varying stress and image protocols, a TID index based on published threshold values was derived for each patient, with >1 considered as TID. We examined the relationship of TID to the presence/extent of CAD, and to a CAD prognostic index. TID was also correlated with patient survival. To address referral bias, survival in a separate cohort of 3,691 patients with a normal perfusion MPI who did not undergo angiography in the 6-month interval was correlated with the presence and severity of TID.

Results

For 28 (29.2%) patients with normal MPI perfusion patterns but with TID, there was no increased incidence of CAD, multivessel or left main disease, or a higher prognostic index compared with no TID. In addition, there was no increased mortality associated with TID in both the angiography cohort and in the patients who did not undergo immediate angiography.

Conclusions

TID in patients with an otherwise normal SPECT MPI study does not increase the likelihood of CAD, its extent or severity, and is not associated with worsened patient survival.