Can a person with pacemaker have CT coronary angiography?

Can a person with pacemaker have CT coronary angiography?

This question is related to the potential problems of MRI in those with cardiac implantable devices, which is well known. There are two aspects to this question. One is regarding the safety of computed tomographic (CT) angiography in those with implanted pacemakers and other cardiac implantable electronic devices (CIED). Second is regarding potential interferences in the evaluation of CT images due to the metallic structures in the implanted devices. US Food and Drugs Administration has reviewed the effects of X-ray irradiation from CT imaging on pacemakers and implantable cardioverter defibrillators in 2019. They have made some valuable conclusions on this aspect [1].

As per the US FDA review, the probability of CT X-rays causing clinically significant interference in CIED is extremely low. Probability of X-ray electromagnetic interference (EMI) is lower when the radiation dose and the radiation dose rate are reduced. Interference can be completely avoided when the implantable device is outside of the primary X-ray beam of the CT scanner [1].

Now what about the artefacts caused by CIED on CT images? In a study of 15 patients undergoing PET/CT no artifacts from pacing leads were identified. But significant artifact was observed in half of the patient studies with ICD leads. The authors suggested software based corrections in CT attenuation correction algorithms for accurate cardiac imaging in the presence of CIED [2].

Streak artifact is an important reason for image degradation in CT imaging. Streak artifacts of pacemaker leads in the superior vena cava can render segments of right coronary artery uninterpretable. Streak artifacts arise from metal active elements of pacemaker or ICD leads near the myocardium. Beam hardening phenomenon due to dense metallic component is one reason. Objects blooming through edge gradient effect due to disparity between the high density of the metal and low density of surrounding blood is another reason. Retrospective ECG gating has been used in CT coronary angiography. Previously degraded portions of the coronary vasculature could be evaluated using this technique [3].

Endocardial leads can limit CT evaluation in all three coronary arteries and has been reported in 29 to 61% of cases. Atrial lead can interfere with the interpretation of right coronary artery. Left ventricular lead in cardiac resynchronization therapy can influence the imaging of left circumflex coronary artery. Even ECG gating process has been mentioned as a cause of image artifacts. Reconstruction of images may be affected by inappropriate double counting of high voltage unipolar pacemaker spikes. Bipolar pacing with smaller pacing spikes do not cause such problems with ECG gating of cardiac CT scans [4].

Single-energy metal artefact reduction (SEMAR) is another technique which has been used in volume data acquired with ECG gating. SEMAR has been shown to reduce metal artifacts from CIED and improve image quality of coronary arteries. In one study 11.7% of coronary segments were rated as non-diagnostic without SEMAR. SEMAR improved the image quality in 9 of the 11 segments and the images became diagnostic [5].

Another study published in 2020 showed that SEMAR reconstruction achieved superior image quality and markedly reduced maximum beam hardening artifact radius and artifact attenuation variation compared to standard reconstruction. The study had 122 clinical cardiac CT studies of patients with implanted metal and a defibrillator lead phantom [6].

References

1. Effects of X-ray irradiation from CT imaging on Pacemakers and Implantable Cardioverter Defibrillators (ICD) – Literature review. Content current as of: 06/13/2019. Available at: https://www.fda.gov/radiation-emitting-products/electromagnetic-compatibility-emc/effects-x-ray-irradiation-ct-imaging-pacemakers-and-implantable-cardioverter-defibrillators-icd Accessed on 30 June 2022.
2. DiFilippo FP, Brunken RC. Do implanted pacemaker leads and ICD leads cause metal-related artifact in cardiac PET/CT? J Nucl Med. 2005 Mar;46(3):436-43. PMID: 15750156.
3. Meyer LT, Boll DT. Novel technique for addressing streak artifact in gated dual-source MDCT angiography utilizing ECG-editing. Eur Radiol. 2008 Nov;18(11):2446-8. doi: 10.1007/s00330-008-1013-y. Epub 2008 May 20. PMID: 18491110.
4. Mak GS, Truong QA. Cardiac CT: Imaging of and Through Cardiac Devices. Curr Cardiovasc Imaging Rep. 2012 Oct 1;5(5):328-336. doi: 10.1007/s12410-012-9150-8. PMID: 23626865; PMCID: PMC3636997.
5. Tatsugami F, Higaki T, Sakane H, Fukumoto W, Iida M, Baba Y, Fujioka C, Kihara Y, Tsushima S, Awai K. Coronary CT angiography in patients with implanted cardiac devices: initial experience with the metal artefact reduction technique. Br J Radiol. 2016 Nov;89(1067):20160493. doi: 10.1259/bjr.20160493. Epub 2016 Sep 29. PMID: 27626704; PMCID: PMC5124846.
6. Groves DW, Acharya T, Steveson C, Schuzer JL, Rollison SF, Nelson EA, Sirajuddin A, Sathya B, Bronson K, Shanbhag SM, Chen MY. Performance of single-energy metal artifact reduction in cardiac computed tomography: A clinical and phantom study. J Cardiovasc Comput Tomogr. 2020 Nov-Dec;14(6):510-515. doi: 10.1016/j.jcct.2020.04.005. Epub 2020 Apr 16. PMID: 32354625.