- Email: [email protected]
Interpretation of optical coherence tomography images
Correspondence
We read with great interest the Clinical Picture reported by Dennis Wong and colleagues (Feb 8, p e11)1 who took advantage of the unprecedented resolution of optical coherence tomography (OCT) to identify the culprit lesion and guide coronary stenting in a patient with acute myocardial infarction. Over the last decade, OCT has become the method of choice to investigate the mechanisms responsible for acute coronary syndromes.2 In this report,1 the authors describe a ruptured thin-cap fibroatheroma with overlying thrombus as cause of acute coronary syndrome. However, this observation raises some important issues. Plaque rupture is typically detected as discontinuity of the fibrous cap overlying a lipid plaque with communication between coronary lumen and plaque cavity.2 Post-mortem and in-vivo studies indicate thin-cap fibroatheroma, consisting of a large necrotic core with thin (less than 65 μm) fibrous cap, as the plaque prone to rupture.2,3 The picture selected by the authors is very unlikely to represent a ruptured thin-cap fibroatheroma, but instead shows a small side branch originating from the main vessel. There is neither lipid plaque nor disrupted fibrous cap. Furthermore, the smooth intraluminal material described as thrombus seems to be blood artifact, possibly related to suboptimum flushing with contrast medium or dextran. Thrombus typically appears as an intraluminal mass with irregular shape adherent to the vessel wall or floating within the lumen.2 In conclusion, we agree with the authors that OCT has great potential to provide insights into the pathogenesis of acute coronary syndromes; however, accurate interpretation of OCT images is crucial to guide clinical decisions. www.thelancet.com Vol 383 May 31, 2014
I-KJ has received grant support and consulting fees from LightLab Imaging/St Jude Medical. The other authors declare no competing interests.
Rocco Vergallo, Haibo Jia, Tsunenari Soeda, Jinwei Tian, *Ik-Kyung Jang [email protected] Cardiology Division, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA (RV, HJ, TS, JT, I-KJ); and Department of Cardiology, Second Affiliated Hospital of Harbin Medical University, Key Laboratory of Myocardial Ischemia, Chinese Ministry of Education, Harbin, China (HJ, JT) 1
2
3
Wong DTL, Soh SY, Nerlekar N, Meredith IT, Malaiapan Y. Identification of concomitant ruptured plaque and intracoronary thrombus by optical coherence tomography. Lancet 2014; 383: e11. Jia H, Abtahian F, Aguirre AD, et al. In vivo diagnosis of plaque erosion and calcified nodule in patients with acute coronary syndrome by intravascular optical coherence tomography. J Am Coll Cardiol 2013; 62: 1748–58. Virmani R, Kolodgie FD, Burke AP, Farb A, Schwartz SM. Lessons from sudden coronary death: a comprehensive morphological classification scheme for atherosclerotic lesions. Arterioscler Thromb Vasc Biol 2000; 20: 1262–75.
The interpretation of the optical coherence tomography (OCT) image provided by Dennis Wong and colleagues1 suggests a plaque rupture with superimposed thombus in one of the lesions. However, by following the luminal contour around vessel circumference, one can appreciate a trilaminar structure of the vessel wall (11–3 o’clock), where the intima is seen as a bright, homogeneous, thin layer, followed by a thin signal-poor media overlying the adventitia. Between 4 and 11 o’clock, the intima is thickened showing a homogeneous, bright signal suggestive of a fibrous plaque. Notably, the luminal contour of the intima is intact along the circumference. The discontinuation at 7 o’clock represents the communication between the lumen and a side branch rather than a plaque rupture. The crescentshaped bright structure in the lumen exhibits a whirly appearance, and could be mistaken for a thrombus,2 as suggested by the authors. However, in this case it suggests insufficient blood removal during image acquisition. The red blood cells scatter the light, causing insufficient visualisation of the
underlying structures. Accordingly, the low signal intensity of the underlying tissue (7–2 o’clock) is due to shadowing from erythrocytes rather than lipid accumulation. Taken together, the published OCT image is of suboptimum quality and shows a fibrous plaque with intact luminal contour. This example shows that interpretation of OCT images needs to be approached with caution, and the most important differential diagnoses, including artifacts,3 should be kept in mind.
Elsevier
Interpretation of optical coherence tomography images
We declare no competing interests.
Maria D Radu, *Lorenz Räber [email protected] Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark (MDR); and Swiss Cardiovascular Center, Bern University Hospital, 3010 Bern, Switzerland (LR) 1
2
3
Wong DTL, Soh SY, Nerlekar N, Meredith IT, Malaiapan Y. Identification of concomitant ruptured plaque and intracoronary thrombus by optical coherence tomography. Lancet 2014; 383: e11. Kume T, Akasaka T, Kawamoto T, et al. Assessment of coronary arterial thrombus by optical coherence tomography. Am J Cardiol 2006; 97: 1713–17. Radu MD, Räber L, Serruys PW. Artefacts with intracoronary optical coherence tomography. In: Radu MD, Räber L, Garcia-Garcia HM, Serruys PW, eds. The Clinical Atlas of Intravascular Optical Coherence Tomography. Toulouse: Europa Edition; 2012.
Is it really concomitant ruptured plaque and intracoronary thrombus? Optical coherence tomography (OCT) is a powerful diagnostic method to assess the underlying plaque in acute coronary syndromes—its high resolution enables plaque composition characterisation and accurate identification of fibrous cap rupture and thrombus.1,2 However, one of the main limitations of this technique is the inability of imaging through blood because of light scattering. For this reason, blood must be displaced during imaging acquisition, usually with simultaneous injection of contrast during pullback. It is important to note that when blood removal is incomplete (for example in large vessels, impaired flow or tight stenosis proximal to the imaging probe), residual blood in the 1887
Correspondence
See Online for appendix
See Online for appendix
lumen causes image artifacts that can lead to mistakes in interpretation.3 Having in mind the limitations of analysis of a single static image, we think that the Clinical Picture presented by Dennis Wong and colleagues,4 is an example of misinterpretation. In our opinion, the image described as thrombus seems to be residual blood, considering its smooth and homogeneous borders and its disposition, with borders concentric with the vessel wall. This amount of blood causes moderate light attenuation that generates a shadow (clearly visible as a sharp transition in the vessel wall at 2 o’clock) but does not prevent visualisation of the vessel wall. Conversely, thrombus usually shows irregular borders and, in the case of red thrombus, it causes intense shadowing that precludes imaging behind the thrombus.3,5 The presence of residual blood also affects the interpretation of the type of plaque. Lipid-rich plaques show hypointense content with diffuse borders and high light attenuation.3 However, in this Clinical Picture4 the attenuation of light is not reduced at the zone marked as lipid, suggesting that the low intensity of the signal is related to shadowing caused by blood. Finally, we think that the image described as a plaque fissure (arrow in the original image)4 is inconclusive, related with the ostium of a small side branch, and might be also caused by incomplete flushing. In the appendix, we provide an example of residual blood that generates an image with very similar characteristics. We believe that OCT is the best method to assess culprit plaques in acute coronary syndromes, but some technical factors must be considered to guarantee proper image interpretation and avoid potential errors. We declare no competing interests.
Santiago Jiménez Valero, Gema Lizcano, Raúl Moreno, José Luis López-Sendón [email protected] 1888
Cardiology Department, Hospital Universitario la Paz, 28046 Madrid, Spain 1
2
3
4
5
Kubo T, Ino Y, Tanimoto T, Kitabata H, Tanaka A, Akasaka T. Optical coherence tomography imaging in acute coronary syndromes. Cardiol Res Pract 2011. DOI:10.4061/2011/312978. Ino Y, Kubo T, Tanaka A, et al. Difference of culprit lesion morphologies between STsegment elevation myocardial infarction and non-ST-segment elevation acute coronary syndrome: an optical coherence tomography study. JACC Cardiovasc Interv 2011; 4: 76–82. Tearney GJ, Regar E, Akasaka T, et al. Consensus standards for acquisition, measurement, and reporting of intravascular optical coherence tomography studies: a report from the International Working Group for Intravascular Optical Coherence Tomography Standardization and Validation. J Am Coll Cardiol 2012; 59: 1058–72. Wong DTL, Soh SY, Nerlekar N, Meredith IT, Malaiapan Y. Identification of concomitant ruptured plaque and intracoronary thrombus by optical coherence tomography. Lancet 2014; 383: e11. Kume T, Akasaka T, Kawamoto T, et al. Assessment of coronary arterial thrombus by optical coherence tomography. Am J Cardiol 2006; 97: 1713–17.
Authors’ reply We would like to express our gratitude for the feedback that we received following our Clinical Picture 1 on a potential ruptured plaque and intracoronary thrombus. We acknowledge the concerns raised about our initial interpretation of the optical coherence tomography (OCT) images. Image interpretation remains the Achilles’ heel of interventional cardiology with invasive intracoronary imaging, but must also always be done in the context of the clinical scenario. In our Clinical Picture,1 a patient who had a recent non-ST segment elevation myocardial infarction had a hazy severe stenosis in the first diagonal artery on coronary angiography. This was then corroborated by OCT, which showed a region where mixed plaque was identified (7 o’clock on our image1). We interpreted the appearance as being consistent with plaque rupture that occurred at the shoulder of a lipid-rich and fibrotic plaque, with overlying thrombus.2 We agree that it is difficult to interpret the dynamic process of a ruptured plaque from a single image. It was suggested that the defect seen at
7 o’clock in our image might have been a side branch. However, with the benefit of longitudinal and circumferential assessment of our image, we are confident that this appearance is indeed that of an ulcer crater and not a branch. All three letters made pertinent observations that the well demarcated intraluminal collection in our image might have been due to blood artifact and not thrombus. Although we recognise the potential for this interpretation, we are confident that this is not the case on the following grounds: first, intraluminal blood artifact was not seen anywhere else in our pullback; second, this appearance was located adjacent to the site of an ulcer crater, which corresponded to the angiographic site of a hazy plaque; and finally, as shown in the longitudinal projection (appendix), the intraluminal collection not only overlies the area of suspected plaque rupture, but also seems to be in contact with the vessel wall. We therefore believe that our Clinical Picture1 represents a rupture at the site of a vulnerable plaque with overlying thrombus.3 We agree that accurate image interpretation is pivotal in the subsequent appropriate management of our patients. We declare no competing interests.
Yuvaraj Malaiapan, *Dennis T L Wong, Peter J Psaltis, Ian T Meredith [email protected] Monash Cardiovascular Research Centre, Department of Medicine, Monash Medical Centre, Monash University and Monash Heart, Southern Health, Clayton, 3168 VIC, Australia (YM, DTLW, PJP, ITM); and South Australian Health & Medical Research Institute, Adelaide, Australia (DTLW, PJP) 1
2
3
Wong DTL, Soh SY, Nerlekar N, Meredith IT, Malaiapan Y. Identification of concomitant ruptured plaque and intracoronary thrombus by optical coherence tomography. Lancet 2014; 383: e11. Jia H, Abtahian F, Aguirre AD, et al. In vivo diagnosis of plaque erosion and calcified nodule in patients with acute coronary syndrome by intravascular optical coherence tomography. J Am Coll Cardiol 2013; 62: 1748–58. Kume T, Akasaka T, Kawamoto T, et al. Assessment of coronary arterial thrombus by optical coherence tomography. Am J Cardiol 2006; 97: 1713–17.
www.thelancet.com Vol 383 May 31, 2014
We read with great interest the Clinical Picture reported by Dennis Wong and colleagues (Feb 8, p e11)1 who took advantage of the unprecedented resolution of optical coherence tomography (OCT) to identify the culprit lesion and guide coronary stenting in a patient with acute myocardial infarction. Over the last decade, OCT has become the method of choice to investigate the mechanisms responsible for acute coronary syndromes.2 In this report,1 the authors describe a ruptured thin-cap fibroatheroma with overlying thrombus as cause of acute coronary syndrome. However, this observation raises some important issues. Plaque rupture is typically detected as discontinuity of the fibrous cap overlying a lipid plaque with communication between coronary lumen and plaque cavity.2 Post-mortem and in-vivo studies indicate thin-cap fibroatheroma, consisting of a large necrotic core with thin (less than 65 μm) fibrous cap, as the plaque prone to rupture.2,3 The picture selected by the authors is very unlikely to represent a ruptured thin-cap fibroatheroma, but instead shows a small side branch originating from the main vessel. There is neither lipid plaque nor disrupted fibrous cap. Furthermore, the smooth intraluminal material described as thrombus seems to be blood artifact, possibly related to suboptimum flushing with contrast medium or dextran. Thrombus typically appears as an intraluminal mass with irregular shape adherent to the vessel wall or floating within the lumen.2 In conclusion, we agree with the authors that OCT has great potential to provide insights into the pathogenesis of acute coronary syndromes; however, accurate interpretation of OCT images is crucial to guide clinical decisions. www.thelancet.com Vol 383 May 31, 2014
I-KJ has received grant support and consulting fees from LightLab Imaging/St Jude Medical. The other authors declare no competing interests.
Rocco Vergallo, Haibo Jia, Tsunenari Soeda, Jinwei Tian, *Ik-Kyung Jang [email protected] Cardiology Division, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA (RV, HJ, TS, JT, I-KJ); and Department of Cardiology, Second Affiliated Hospital of Harbin Medical University, Key Laboratory of Myocardial Ischemia, Chinese Ministry of Education, Harbin, China (HJ, JT) 1
2
3
Wong DTL, Soh SY, Nerlekar N, Meredith IT, Malaiapan Y. Identification of concomitant ruptured plaque and intracoronary thrombus by optical coherence tomography. Lancet 2014; 383: e11. Jia H, Abtahian F, Aguirre AD, et al. In vivo diagnosis of plaque erosion and calcified nodule in patients with acute coronary syndrome by intravascular optical coherence tomography. J Am Coll Cardiol 2013; 62: 1748–58. Virmani R, Kolodgie FD, Burke AP, Farb A, Schwartz SM. Lessons from sudden coronary death: a comprehensive morphological classification scheme for atherosclerotic lesions. Arterioscler Thromb Vasc Biol 2000; 20: 1262–75.
The interpretation of the optical coherence tomography (OCT) image provided by Dennis Wong and colleagues1 suggests a plaque rupture with superimposed thombus in one of the lesions. However, by following the luminal contour around vessel circumference, one can appreciate a trilaminar structure of the vessel wall (11–3 o’clock), where the intima is seen as a bright, homogeneous, thin layer, followed by a thin signal-poor media overlying the adventitia. Between 4 and 11 o’clock, the intima is thickened showing a homogeneous, bright signal suggestive of a fibrous plaque. Notably, the luminal contour of the intima is intact along the circumference. The discontinuation at 7 o’clock represents the communication between the lumen and a side branch rather than a plaque rupture. The crescentshaped bright structure in the lumen exhibits a whirly appearance, and could be mistaken for a thrombus,2 as suggested by the authors. However, in this case it suggests insufficient blood removal during image acquisition. The red blood cells scatter the light, causing insufficient visualisation of the
underlying structures. Accordingly, the low signal intensity of the underlying tissue (7–2 o’clock) is due to shadowing from erythrocytes rather than lipid accumulation. Taken together, the published OCT image is of suboptimum quality and shows a fibrous plaque with intact luminal contour. This example shows that interpretation of OCT images needs to be approached with caution, and the most important differential diagnoses, including artifacts,3 should be kept in mind.
Elsevier
Interpretation of optical coherence tomography images
We declare no competing interests.
Maria D Radu, *Lorenz Räber [email protected] Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark (MDR); and Swiss Cardiovascular Center, Bern University Hospital, 3010 Bern, Switzerland (LR) 1
2
3
Wong DTL, Soh SY, Nerlekar N, Meredith IT, Malaiapan Y. Identification of concomitant ruptured plaque and intracoronary thrombus by optical coherence tomography. Lancet 2014; 383: e11. Kume T, Akasaka T, Kawamoto T, et al. Assessment of coronary arterial thrombus by optical coherence tomography. Am J Cardiol 2006; 97: 1713–17. Radu MD, Räber L, Serruys PW. Artefacts with intracoronary optical coherence tomography. In: Radu MD, Räber L, Garcia-Garcia HM, Serruys PW, eds. The Clinical Atlas of Intravascular Optical Coherence Tomography. Toulouse: Europa Edition; 2012.
Is it really concomitant ruptured plaque and intracoronary thrombus? Optical coherence tomography (OCT) is a powerful diagnostic method to assess the underlying plaque in acute coronary syndromes—its high resolution enables plaque composition characterisation and accurate identification of fibrous cap rupture and thrombus.1,2 However, one of the main limitations of this technique is the inability of imaging through blood because of light scattering. For this reason, blood must be displaced during imaging acquisition, usually with simultaneous injection of contrast during pullback. It is important to note that when blood removal is incomplete (for example in large vessels, impaired flow or tight stenosis proximal to the imaging probe), residual blood in the 1887
Correspondence
See Online for appendix
See Online for appendix
lumen causes image artifacts that can lead to mistakes in interpretation.3 Having in mind the limitations of analysis of a single static image, we think that the Clinical Picture presented by Dennis Wong and colleagues,4 is an example of misinterpretation. In our opinion, the image described as thrombus seems to be residual blood, considering its smooth and homogeneous borders and its disposition, with borders concentric with the vessel wall. This amount of blood causes moderate light attenuation that generates a shadow (clearly visible as a sharp transition in the vessel wall at 2 o’clock) but does not prevent visualisation of the vessel wall. Conversely, thrombus usually shows irregular borders and, in the case of red thrombus, it causes intense shadowing that precludes imaging behind the thrombus.3,5 The presence of residual blood also affects the interpretation of the type of plaque. Lipid-rich plaques show hypointense content with diffuse borders and high light attenuation.3 However, in this Clinical Picture4 the attenuation of light is not reduced at the zone marked as lipid, suggesting that the low intensity of the signal is related to shadowing caused by blood. Finally, we think that the image described as a plaque fissure (arrow in the original image)4 is inconclusive, related with the ostium of a small side branch, and might be also caused by incomplete flushing. In the appendix, we provide an example of residual blood that generates an image with very similar characteristics. We believe that OCT is the best method to assess culprit plaques in acute coronary syndromes, but some technical factors must be considered to guarantee proper image interpretation and avoid potential errors. We declare no competing interests.
Santiago Jiménez Valero, Gema Lizcano, Raúl Moreno, José Luis López-Sendón [email protected] 1888
Cardiology Department, Hospital Universitario la Paz, 28046 Madrid, Spain 1
2
3
4
5
Kubo T, Ino Y, Tanimoto T, Kitabata H, Tanaka A, Akasaka T. Optical coherence tomography imaging in acute coronary syndromes. Cardiol Res Pract 2011. DOI:10.4061/2011/312978. Ino Y, Kubo T, Tanaka A, et al. Difference of culprit lesion morphologies between STsegment elevation myocardial infarction and non-ST-segment elevation acute coronary syndrome: an optical coherence tomography study. JACC Cardiovasc Interv 2011; 4: 76–82. Tearney GJ, Regar E, Akasaka T, et al. Consensus standards for acquisition, measurement, and reporting of intravascular optical coherence tomography studies: a report from the International Working Group for Intravascular Optical Coherence Tomography Standardization and Validation. J Am Coll Cardiol 2012; 59: 1058–72. Wong DTL, Soh SY, Nerlekar N, Meredith IT, Malaiapan Y. Identification of concomitant ruptured plaque and intracoronary thrombus by optical coherence tomography. Lancet 2014; 383: e11. Kume T, Akasaka T, Kawamoto T, et al. Assessment of coronary arterial thrombus by optical coherence tomography. Am J Cardiol 2006; 97: 1713–17.
Authors’ reply We would like to express our gratitude for the feedback that we received following our Clinical Picture 1 on a potential ruptured plaque and intracoronary thrombus. We acknowledge the concerns raised about our initial interpretation of the optical coherence tomography (OCT) images. Image interpretation remains the Achilles’ heel of interventional cardiology with invasive intracoronary imaging, but must also always be done in the context of the clinical scenario. In our Clinical Picture,1 a patient who had a recent non-ST segment elevation myocardial infarction had a hazy severe stenosis in the first diagonal artery on coronary angiography. This was then corroborated by OCT, which showed a region where mixed plaque was identified (7 o’clock on our image1). We interpreted the appearance as being consistent with plaque rupture that occurred at the shoulder of a lipid-rich and fibrotic plaque, with overlying thrombus.2 We agree that it is difficult to interpret the dynamic process of a ruptured plaque from a single image. It was suggested that the defect seen at
7 o’clock in our image might have been a side branch. However, with the benefit of longitudinal and circumferential assessment of our image, we are confident that this appearance is indeed that of an ulcer crater and not a branch. All three letters made pertinent observations that the well demarcated intraluminal collection in our image might have been due to blood artifact and not thrombus. Although we recognise the potential for this interpretation, we are confident that this is not the case on the following grounds: first, intraluminal blood artifact was not seen anywhere else in our pullback; second, this appearance was located adjacent to the site of an ulcer crater, which corresponded to the angiographic site of a hazy plaque; and finally, as shown in the longitudinal projection (appendix), the intraluminal collection not only overlies the area of suspected plaque rupture, but also seems to be in contact with the vessel wall. We therefore believe that our Clinical Picture1 represents a rupture at the site of a vulnerable plaque with overlying thrombus.3 We agree that accurate image interpretation is pivotal in the subsequent appropriate management of our patients. We declare no competing interests.
Yuvaraj Malaiapan, *Dennis T L Wong, Peter J Psaltis, Ian T Meredith [email protected] Monash Cardiovascular Research Centre, Department of Medicine, Monash Medical Centre, Monash University and Monash Heart, Southern Health, Clayton, 3168 VIC, Australia (YM, DTLW, PJP, ITM); and South Australian Health & Medical Research Institute, Adelaide, Australia (DTLW, PJP) 1
2
3
Wong DTL, Soh SY, Nerlekar N, Meredith IT, Malaiapan Y. Identification of concomitant ruptured plaque and intracoronary thrombus by optical coherence tomography. Lancet 2014; 383: e11. Jia H, Abtahian F, Aguirre AD, et al. In vivo diagnosis of plaque erosion and calcified nodule in patients with acute coronary syndrome by intravascular optical coherence tomography. J Am Coll Cardiol 2013; 62: 1748–58. Kume T, Akasaka T, Kawamoto T, et al. Assessment of coronary arterial thrombus by optical coherence tomography. Am J Cardiol 2006; 97: 1713–17.
www.thelancet.com Vol 383 May 31, 2014