Co-registration of Intravascular Ultrasound With Angiographic Imaging for Carotid Artery Disease.

BACKGROUND: Intravascular ultrasound (IVUS) provides endoluminal views and cross-sectional images of carotid arteries but lacks overview of vascular territory provided by angiography. Co-registration of IVUS with angiographic images may provide the potential to navigate both imaging modalities in a synchronous manner. The objective of this study is to evaluate the feasibility and accuracy of co-registering both imaging modalities in the carotid vasculature of the neck. METHODS: Fourteen patients with 15 cervical carotid artery lesions underwent angiography and subsequent treatment. In each case, an IVUS catheter was advanced to the target lesion and a reference angiography sequence was acquired. This was followed by an electrocardiography-triggered fluoroscopy sequence that was initiated upon IVUS catheter pullback. IVUS data collected during pullback were registered with fluoroscopy and evaluated for error and clinical usability. RESULTS: A total of 32 landmarks were identified that demonstrated reasonable agreement during IVUS-angiography co-registration. There was a mean registration error distance of 3.36 mm (SD 2.82 mm) between targets. The longitudinal extent and severity of the disease through the target segment could be easily evaluated after co-registration. CONCLUSION: Semiautomatic tracking and co-registration of angiography and IVUS is a new technology and has the potential to increase the use of IVUS in carotid disease and to proivde the opportunity to optimize procedural outcomes.

Co-registration of angiography and intravascular ultrasound images through image-based device tracking.

OBJECTIVES: To determine the feasibility of automated co-registration of angiography and intravascular ultrasound (IVUS) to facilitate integration of these two imaging modalities in a synchronous manner. BACKGROUND: IVUS provides cross-sectional imaging of coronary arteries but lacks overview of the vascular territory provided by angiography. Co-registration of angiography and IVUS would increase utility of IVUS in the clinical setting. METHODS: Forty-nine consecutive patients undergoing surveillance for cardiac allograft vasculopathy with angiography and IVUS of the left anterior descending artery (LAD) were enrolled. A pre-IVUS angiogram of the LAD was performed followed by an ECG-triggered fluoroscopy (ECGTF) during IVUS pullback at 0.5 mm/s using an automatic pullback device. ECGTF was used to track the IVUS catheter during pullback and establish a spatial relationship to the pre-IVUS angiogram. Angio-IVUS co-registration was performed with a research prototype (Siemens Healthcare, Germany) and accuracy was evaluated by distance mismatch between angiography and IVUS images at vessel bifurcations. RESULTS: Median age was 54 (44.5, 67) years. The population was 82.6% male with minimal risk factors. The median (IQR) co-registration distance mismatch measured at 108 bifurcations in 42 (85%) patients was 0.35 (0.00-1.16) mm. Seven patients were excluded due to inappropriate data acquisition (n = 3) and failure of tracking (n = 4), e.g., due to overlapping sternal wires. Estimated effective radiation dose for ECGTF was 0.09 mSv. CONCLUSION: This study demonstrates the feasibility of angio-IVUS co-registration which may be used as a clinical tool for localizing IVUS cross-sections along an angiographic roadmap. © 2015 Wiley Periodicals, Inc.

"Contrast-less" stent-assisted coiling of an A1 aneurysm.

BACKGROUND: Iodine-based contrast medium used in diagnostic and therapeutic cerebrovascular imaging may cause renal toxicity, especially in patients with underlying renal impairment. Contrast dilution may impede efforts of the neurointerventionalist to treat intracranial vascular pathology. METHODS: A 36-year-old man with renal impairment presented with an unruptured A1 segment anterior cerebral artery aneurysm. Previously obtained magnetic resonance angiography was fused with intraoperative noncontrast computed tomography and live 2-dimensional fluoroscopic images. The aneurysm was successfully treated with stent-assisted coil embolization without the use of contrast. RESULTS: Neurointervention without contrast was feasible, and although the presented case is one example, the imaging fusion techniques used in this case can substantially decrease the exposure to contrast and subsequent risk of renal injury during intracranial procedures. CONCLUSIONS: Further development of and experience with this technique is needed to improve its safety and efficacy.

Frameless neuronavigation based only on 3D digital subtraction angiography using surface-based facial registration.

OBJECT: Cerebrovascular lesions can have complicated abnormal anatomy that is not completely characterized by CT or MR angiography. Although 3D rotational angiography provides superior spatial and temporal resolution, catheter angiograms are not easily registered to the patient, limiting the use of these images as a source for neuronavigation. However, 3D digital subtraction angiography (DSA) contains not only vascular anatomy but also facial surface anatomy data. The authors report a novel technique to register 3D DSA images by using only the surface anatomy contained within the data set without having to fuse the DSA image set to other imaging modalities or use fiducial markers. METHODS: A cadaver model was first created to assess the accuracy of neuronavigation based on 3D DSA images registered by facial surface anatomy. A 3D DSA scan was obtained of a formalin-fixed cadaver head, with acquisitions of mask and contrast runs. The right common carotid artery was injected prior to the contrast run with a 45% contrast solution diluted with water-soluble red liquid latex. One week later, the head was registered to a neuronavigation system loaded with the 3D DSA images acquired earlier using facial surface anatomy. A right pterional craniotomy was performed and 10 different vascular landmarks were identified and measured for accuracy using the neuronavigation system. Neuronavigation based only on 3D DSA was then used to guide an open clipping procedure for a patient who presented with a ruptured distal lenticulostriate aneurysm. RESULTS: The accuracy of the measurements for the cadaver model was 0.71 ± 0.25 mm (mean ± SE), which is superior to the 1.8-5 mm reported for neuronavigation. The 3D DSA-based navigation-assisted surgery for the distal lenticulostriate aneurysm aided in localization, resulting in a small craniotomy and minimal brain dissection. CONCLUSIONS: This is the first example of frameless neuronavigation based on 3D catheter angiography registered by only the surface anatomy data contained within the 3D DSA image set. This is an easily applied technique that is beneficial for accurately locating vascular pathological entities and reducing the dissection burden of vascular lesions.

Intraprocedural parenchymal blood volume as a marker of reperfusion status in acute ischemic stroke intervention.

Parenchymal blood volume (PBV) mapping with flat panel detectors may provide real-time estimates of tissue perfusion during endovascular ischemic stroke procedures. We present two cases of acute middle cerebral artery (MCA) occlusion to demonstrate how PBV may: (1) be used in acute stroke; (2) influence intraprocedural decision-making; and (3) potentially serve as a predicator of clinical outcome. Both cases were successfully recanalized with endovascular embolectomy. Intraprocedural PBV maps were obtained immediately before and after recanalization. Pre-intervention reductions in PBV were seen throughout the MCA territory in both cases, with significant improvement in PBV in one case with good radiographic and clinical outcome and a lack of improvement in PBV in the second case with a large infarct volume. PBV deficit normalization may occur with recanalization of the parent artery and probably represents successful reperfusion. Baseline PBV maps should therefore be interpreted with caution and not interpreted to represent irreversible core infarct.

Intraprocedural parenchymal blood volume as a marker of reperfusion status in acute ischemic stroke intervention.

Parenchymal blood volume (PBV) mapping with flat panel detectors may provide real-time estimates of tissue perfusion during endovascular ischemic stroke procedures. We present two cases of acute middle cerebral artery (MCA) occlusion to demonstrate how PBV may: (1) be used in acute stroke; (2) influence intraprocedural decision-making; and (3) potentially serve as a predicator of clinical outcome. Both cases were successfully recanalized with endovascular embolectomy. Intraprocedural PBV maps were obtained immediately before and after recanalization. Pre-intervention reductions in PBV were seen throughout the MCA territory in both cases, with significant improvement in PBV in one case with good radiographic and clinical outcome and a lack of improvement in PBV in the second case with a large infarct volume. PBV deficit normalization may occur with recanalization of the parent artery and probably represents successful reperfusion. Baseline PBV maps should therefore be interpreted with caution and not interpreted to represent irreversible core infarct.

Contrast-enhanced coronary artery visualization by dual-source computed tomography--initial experience.

UNLABELLED: Multi-detector computed tomography (CT) scanners, by virtue of their high temporal and spatial resolution, permit imaging of the coronary arteries. However, motion artifacts, especially in patients with higher heart rates, can impair image quality. We thus evaluated the performance of a new dual-source CT (DSCT) with a heart rate independent temporal resolution of 83 ms for the visualization of the coronary arteries in 14 consecutive patients. METHODS: Fourteen patients (mean age 61 years, mean heart rate 71 min(-1)) were studied by DSCT. The system combines two arrays of an X-ray tube plus detector (64 slices) mounted on a single gantry at an angle of 90 degrees With a rotation speed of 330 ms, a temporal resolution of 83 ms (one-quarter rotation) can be achieved independent of heart rate. For data acquisition, intraveous contrast agent was injected at a rate of 5 ml/s. Images were reconstructed with 0.75 slice thickness and 0.5 mm increment. The data sets were evaluated concerning visibility of the coronary arteries and occurrence of motion artifact. RESULTS: Visualization of the coronary arteries was successful in all patients. Most frequently, image reconstruction at 70% of the cardiac cycle provided for optimal image quality (50% of patients). Of a total of 226 coronary artery segments, 222 (98%) were visualized free of motion artifact. In summary, DSCT constitutes a promising new concept for cardiac CT. High and heart rate independent temporal resolution permits imaging of the coronary arteries without motion artifacts in a substantially increased number of patients as compared to earlier scanner generations. Larger and appropriately designed studies will need to determine the method's accuracy for detection of coronary artery stenoses.