Table 1.
Validation studies of IVUS and IVUS based imaging modalities
| Author | Study settings | Year | Primary objective | Results |
|---|---|---|---|---|
| Greyscale IVUS | ||||
| Palmer [24] | In vitro | 1999 | IVUS for coronary atheromatous lesions compared to histology. Atheromatous plaque was classified as echodense, echolucent, heterogeneous or calcified by each observer and by one observer on separate occasions | Overall inter- and intra-observer reproducibility for plaque-type (Kappa 0.87[0.80–0.94] and 0.89[0. 85–0.93 respectively]) and focal calcification (0.78[0.74–0.82] and 0.88[0.84–0.92]) was high |
| Agreement for overall plaque type between intravascular ultrasound and histology occurred in 89% of sites (Kappa 0.73[0.69–0. 77]). Specificity ≥90% | ||||
| Prati [25] | In vitro | 2001 | IVUS, high frequency transducer(40 MHz) for plaque composition compared to histomorphology | Lipid pools were observed by histology in 30 sections (25%). IVUS revealed the presence of lipid pools in 19 of these sections (16%; sensitivity 65%]. Specificity ≥95% |
| Lipid/necrotic areas were defined by IVUS as large echolucent intraplaque areas surrounded by tissue with higher echodensity | ||||
| VH IVUS | ||||
| Nair [15] | Ex vivo | 2002 | Coronary plaque classification with intravascular ultrasound radiofrequency data analysis | Autoregressive classification schemes performed better than those from classic Fourier spectra with accuracies of 90.4% for fibrous, 92.8% for fibrolipidic, 90.9% for calcified, and 89.5% for calcified-necrotic regions in the training data set and 79.7, 81.2, 92.8, and 85.5% in the test data, respectively |
| Nasu [26] | In vivo | 2006 | Accuracy of in vivo coronary plaque morphology assessment: a validation study of in vivo virtual histology compared with in vitro histopathology | Predictive accuracy from all patients data: 87.1% for fibrous, 87.1% for fibro-fatty, 88.3% for necrotic core, and 96.5% for dense calcium regions, respectively |
| Sensitivities: NC:67.3%, FT:86%, FF:79.3%, DC:50%. Specificities: NC:92.9%, FT:90.5%,FF:100%, DC:99% | ||||
| Nair [16] | Ex vivo | 2007 | Automated coronary plaque characterisation with intravascular ultrasound backscatter: ex vivo validation | The overall predictive accuracies were 93.5% for FT, 94.1% for FF, 95.8% for NC, and 96.7% for DC |
| Sensitivities: NC:91.7%, FT:95.7%, FF:72.3%, DC:86.5%. Specificities: NC:96.6%, FT:90.9%, FF:97.9%, DC:98.9% | ||||
| Granada [27] | Ex vivo | 2007 | In vivo plaque characterization using intravascular ultrasound-virtual histology in a porcine model of complex coronary lesions | Compared with histology, IVUS-VH correctly identified the presence of fibrous, fibro-fatty, and necrotic tissue in 58.33, 38.33, and 38.33% of lesions, respectively |
| Sensitivities: fibrous 76.1%, fibro-fatty 46%, and necrotic core 41.1% | ||||
| Van Herk [28] | Ex vivo | 2009 | Validation of in vivo plaque characterisation by virtual histology in a rabbit model of atherosclerosis | VH-IVUS had a high sensitivity, specificity and positive predictive value for the detection of non-calcified thin cap fibroatheroma (88, 96, 87%, respectively) and calcified thin cap fibroatheroma (95, 99, 93%, respectively). These values were respectively 82, 94, 85% for non-calcified fibroatheroma and 78, 98, 84% for calcified fibroatheroma. The lowest values were obtained for pathological intimal thickening (74, 92, 70%, respectively). For all plaque types, VH-IVUS had a kappa-value of 0.79 |
| Thim [29] | Ex vivo | 2010 | Unreliable assessment of necrotic core by VHTM IVUS in porcine coronary artery disease | No correlations were found between the size of the necrotic core determined by VH IVUS and histology. VH IVUS displayed necrotic cores in lesions lacking cores by histology |
| IB IVUS | ||||
| Kawasaki [22] | In vivo | 2002 | In vivo quantitative tissue characterization of human coronary arterial plaques by use of integrated backscatter intravascular ultrasound and comparison with angioscopic findings | r:0,954 for each category, DC, FF, FT, NC |
| Kawasaki [23] | In vivo | 2006 | Diagnostic accuracy of optical coherence tomography and integrated backscatter intravascular ultrasound images for tissue characterization of human coronary plaques | Sensitivities: DC:100% FT:94% Lipid pool:84% |
| Specificities: DC:99% FT:84% Lipid pool:97% | ||||
| Okubo [18] | Ex vivo | 2008 | Development of integrated backscatter intravascular ultrasound for tissue characterization of coronary plaques | IB classified fibrous, lipid-rich and fibrocalcific plaque components with a high accuracy of 93, 90 and 96%, respectively |
| iMAP | ||||
| Sathyanarayana [17] | In vivo | 2009 | Characterisation of atherosclerotic plaque by spectral similarity of radiofrequency intravascular ultrasound signals | Ex vivo validation demonstrated accuracies at the highest level of confidence as: 97, 98, 95, and 98% for necrotic, lipidic, fibrotic and calcified regions respectively |
| Echogenicity | ||||
| Bruining [19] | Ex vivo | 2007 | Three-dimensional and quantitative analysis of atherosclerotic plaque composition by automated differential echogenicity | Areas of hypoechogenicity correlated with the presence of smooth muscle cells. Areas of hyperechogenicity correlated with presence of collagen, and areas of hyperechogenicity with acoustic shadowing correlated with calcium |