Flat Choroidal Nevus Inaccessible to Ultrasound Sonography Evaluated by Enhanced Depth Imaging Optical Coherence Tomography

Purpose: To demonstrate the usefulness of enhanced depth imaging optical coherence tomography (EDI-OCT) in investigating choroidal lesions inaccessible to ultrasound sonography. Methods: In a 60-year-old woman with an asymptomatic choroidal nevus, normal OCT was used to observe the macula and EDI-OCT to image the choroidal nevus that was inaccessible to ultrasound. The exact location of the lesion in the choroid and the dimensions of the nevus were measured. Results: The lesion was located in the superior macula, and the nevus was homogeneous in its reflectivity. We observed a thickened choroid delineated by the shadow cone behind it, measuring 1,376 × 325 µm in the larger vertical cut and 1,220 × 325 µm in the larger horizontal cut in an image with a 1:1 pixel mapping and automatic zoom. The macular profile and thickness were both normal. Conclusions: EDI-OCT appears to be an excellent technique for measuring choroidal nevi and all choroidal lesions accessible to OCT imaging by depicting their exact location in the choroid, their dimensions, and their demarcation from the surrounding healthy tissue, thus allowing for a more efficient and accurate follow-up

In-vivo accuracy of geometrically correct three-dimensional reconstruction of human coronary arteries: is it influenced by certain parameters?

OBJECTIVE: The geometrically correct three-dimensional reconstruction of human coronary arteries by integrating intravascular ultrasound (IVUS) and biplane angiography constitutes a promising imaging method for coronaries with broad clinical potential. The determinants of the accuracy of the method, however, have not been investigated before. METHODS: In total, 17 arterial segments (right coronary artery, n=7; left anterior descending, n=4; left circumflex, n=6) derived from nine patients were three-dimensionally reconstructed by applying three-dimensional intravascular ultrasound. The degree of matching between the reconstructed lumen back-projected onto each angiographic plane and the actual lumen in each plane was used as a measure of method's accuracy. The investigated factors that could potentially affect the reliability of the method included the type of the artery (left anterior descending, left circumflex, right coronary artery) and several geometrical and morphological characteristics of the reconstructed arteries. RESULTS: The correlation between the back-projected reconstructed lumens and the actual angiographic ones was found to be high (r=0.78, P<0.001). Neither the category of the reconstructed arteries nor their particular geometrical and morphological characteristics influenced the accuracy of the reconstruction method significantly. Nonetheless, the method exhibited slightly less accuracy in the reconstruction of right coronary arteries, an observation that could be attributed to the more intense pulsatile motion that this artery experiences during the cardiac cycle compared to the left anterior descending and left circumflex artery. CONCLUSIONS: The in-vivo accuracy of three-dimensional intravascular ultrasound (3D IVUS) is significantly high regardless of the type of the coronary arteries or their particular geometrical and morphological characteristics. This finding further supports the applicability of the method for either diagnostic or investigational purposes

In vivo comparative study of linear versus geometrically correct three-dimensional reconstruction of coronary arteries

Although conventional linear 3-dimensional (3D) reconstruction of coronary arteries by intravascular ultrasound has been widely used for the assessment of plaque volume and progression; the volumetric error (VE) that is produced has not been adequately studied. Linear and geometrically correct 3D reconstruction was applied in 16 coronary arterial segments from 9 patients. Using geometrically correct reconstruction as reference, VE was assessed in 1-mm-long arterial slices. Although for the entire length of the coronary arteries VEs for lumen, external elastic membrane (EEM), and intima-media volumes were minimal (lumen VE 0.4%, -0.8 to 1.8; EEM VE 0.3%, -0.9 to 1.9; intima-media VE 0.4%, -1.4 to 2.2), the VE in each arterial slice exhibited a large variation from -15.6% to 36.2% for lumen volume, from -12.9% to 33.1% for EEM volume, and from -17.2% to 46.7% for intima-media volume, suggesting that linear reconstruction over- or underestimates the true arterial volumes. Lumen VE, EEM VE, and intima-media VE were also significantly higher in curved arterial subsegments than in relatively straight arterial subsegments (p <0.05). In conclusion, in highly curved arterial subsegments, the VE that is produced by linearly stacking the intravascular ultrasound images may be not negligible. Geometrically correct reconstruction of coronary arteries provides more reliable arterial reconstructions and plaque volume measurements. It is anticipated that clinical application of this technique will contribute to more accurate follow-up of the progression of atherosclerosis and assessment of arterial remodeling