Three-dimensional vessel wall MRI to characterize thrombus prior to endovascular thrombectomy for large vessel occlusion stroke.

BACKGROUND AND PURPOSE: Endovascular thrombectomy (EVT) for acute ischemic stroke (AIS) caused by large vessel occlusion requires rapid and reliable imaging of the vessel course including the clot to reduce complications and ensure success. However, no method to acquire this information has been established. METHODS: Six consecutive patients with AIS caused by large vessel occlusion underwent EVT in our institute. High-resolution vessel wall MRI was performed using three-dimensional (3D) variable refocusing flip angle pulse and turbo spin-echo sequences (VRFA-TSE) with the volume isotropic turbo spin-echo acquisition (VISTA) technique. This study evaluated the effectiveness of 3D proton density-weighted (PDW) VRFA-TSE (called PDW-VISTA) compared with T2-weighted (T2W) VRFA-TSE (called T2W-VISTA) to demonstrate the cerebral vessels including the occluded invisible lesion. RESULTS: PDW-VISTA and T2W-VISTA were successfully performed in all cases. PDW-VISTA was more useful to visualize the anterior circulation than T2W-VISTA by clearly revealing invisible vessels, whereas PDW-VISTA and T2W-VISTA had similar findings in the posterior circulation. The vessel courses shown by 3D PDW-VISTA imaging before treatment and digital subtraction angiography after treatment showed good agreement in all cases. Furthermore, 3D PDW-VISTA imaging demonstrated the length and size of the clot. CONCLUSIONS: PDW-VISTA imaging was found to more clearly depict the cerebral vessels including occluded lesion than T2W-VISTA imaging. Findings of thrombus size and length were important for correctly placing the stent retriever and securing safety during the procedure.

Relationship between coronary diastolic pressure indexes during the wave-free period and a novel pressure-derived index: Diastolic pressure ratio at the optimal point.

OBJECTIVES: We aimed to determine the diastolic pressure ratio at the optimal point (DROP) using a simple measurement algorithm and to compare DROP with distal coronary-to-aortic pressure ratios during the wave-free period (PRWFP ) and at the mid-diastolic point (PRMD ). METHODS: Distal coronary and aortic pressures were measured from color pressure images of 440 beats in 48 patients with coronary stenoses. The DROP measurement point was 67% for one beat between the two rising points on the aortic pressure curve according to the distribution of the wave-free period and the mid-diastolic point. RESULTS: DROP correlated closely with PRWFP (r = 0.993, P < 0.0001) and PRMD (r = 0.997, P < 0.0001). The diagnostic efficiency was excellent (area under the receiver-operating characteristic curve, 0.997) for both PRWFP ≤ 0.89 (specificity, 0.99; sensitivity, 0.96) and PRMD ≤ 0.89 (specificity, 0.95; sensitivity, 1.00). CONCLUSIONS: A simple pressure-derived physiological marker of coronary stenosis, DROP, might represent other diastolic pressure indexes with a numerical equivalency to the instantaneous wave-free ratio. DROP can be measured automatically assuming that the rising points on the aortic pressure curve are detectable. However, further large-scale clinical investigations are needed to determine whether DROP could contribute to the further generalization of physiology-guided percutaneous coronary intervention.

Differences of side branch jailing between left main-left anterior descending artery stenting and left main-left circumflex artery stenting with Nobori biolimus-eluting stent.

The aim of this study is to indicate differences of side branch jailing between the left main (LM)-left anterior descending artery (LAD) stenting and the LM-left circumflex artery (LCx) stenting. Thirty-one patients who underwent single-stenting using a two-link ten-crowns biolimus-eluting stent (Japanese design of BES, J-BES) and subsequent kissing balloon dilation (KBD) on an LM bifurcation with optical coherence tomography (OCT) were divided into two groups according to the stented vessel. Bifurcation angles were measured by three-dimensional (3D) quantitative coronary analysis. The jailing pattern on a side branch ostium was evaluated by stent-enhanced 3D-OCT. Incomplete stent apposition (ISA) after KBD was compared between the stented vessels. The to-be-stented angle of the LM-LCx stenting (n = 11) was significantly steeper than that of the LM-LAD stenting (n = 20) (132.6° ± 16.9° vs. 150.7° ± 10.6°, p < 0.01). The incidence of the free carina type, which has no stent links bridging from a carina, in the LM-LCx stenting was significantly higher than that in the LM-LAD stenting (90.9 vs. 45.0 %, p = 0.02). The percentage of ISA at the bifurcation segment in the LM-LCx stenting was significantly smaller than that in the LM-LAD stenting (4.4 ± 8.2 vs. 12.7 ± 9.2 %, p = 0.0003). This study showed, by higher incidence of the favorable configuration, that the LM-LCx stenting achieved a smaller percentage of ISA than the LM-LAD stenting. These insights may help guide LM bifurcation stenting with J-BES.

Guide wire shadow assessed by shading index is reduced in sparse spring coil wire in optical coherence tomography.

One of the major problems of a Fourier-domain optical coherence tomography (FD-OCT) is the guide wire (GW) shadow which disturbs precise coronary assessment. If two or more GWs are used in a bifurcation PCI, the GW shadow becomes larger. In FD-OCT, GWs were usually observed as a crescent shape, but GWs with the sparse spring coil were observed as either round or crescent shape. The measured angle making GW shadow of GW without the sparse spring coil was similar to its theoretical angle (30.4 ± 1.7° vs. 30.1 ± 0.7°, p = 0.21); however, the measured angle of GW with the sparse spring coil was significantly smaller than its theoretical angle (16.8 ± 4.8° vs. 28.7 ± 1.5°, p < 0.01). For standardization of shading-effect of GW, a virtual diameter of GW which was calculated from a measured angle, an actual diameter of GW, and a distance between an imaging catheter and GW was defined as the shading index. The shading index of GW with the sparse spring coil was significantly smaller than that of GW without the sparse spring coil (0.008 ± 0.002 vs. 0.014 ± 0.001, p < 0.01). Shading indices of GWs with the sparse spring coil were smaller than their actual diameters. The sparse spring coil structure could contribute to the reduction of the GW shadow in FD-OCT. Also, we proposed the new and useful shading index to indicate the shading-effect of GW.

Novel and quick coronary image analysis by instant stent-accentuated three-dimensional optical coherence tomography system in catheterization laboratory.

In order to confirm the relation between stent struts and the jailed side branch (SB), the actual wire re-crossing position and the optimal wire re-crossing position during a bifurcation stenting, we developed the instant stent-accentuated three-dimensional optical coherence tomography (iSA 3D-OCT) system based on a novel algorithm. Stent struts in two-dimensional optical coherence tomography (2D-OCT) are represented as high-intensity line segments or spots in low-intensity background. Stent struts disappear and a vessel image is created by the mean filter followed by the minimum filter. A strut image is created by subtracting a vessel image from an original image, and accentuated. By adding a vessel image to a strut image, iSA 2D-OCT is created. It took only 3 s to accentuate stent struts of 100 frames by ImageJ with its macro program. By the iSA 3D-OCT system which consists of the console of OCT, the USB selector, USB cables, the USB flash drive, the computer, and three freeware programs, it took about 65 s from an export of the image data to an observation of iSA 3D-OCT semi-automatically. During a bifurcation stenting procedure, we could confirm the relation between stent struts and the jailed SB, the actual wire re-crossing position and the optimal wire re-crossing position. Using the iSA 3D-OCT system, a detailed process during a bifurcation PCI can be observed in very short waiting time, about 65 s. It is expected to improve the outcome of a complicated bifurcation PCI by the iSA 3D-OCT system.