MRA Images Research Articles

Stent-Assisted Coiling in Endovascular Treatment of 500 Consecutive Cerebral Aneurysms with Long-Term Follow-Up

Stent-assisted coil embolization has become one of the most preferred techniques in the treatment of wide-neck intracranial aneurysms; however, long-term patency and safety of the self-expanding neurostents and their role in durability of the endovascular treatment has remained ambiguous. We sought to retrospectively examine the long-term results of self-expanding stent usage in conjunction with coil embolization in treatment of wide-neck cerebral aneurysms. We coiled 500 wide-neck cerebral aneurysms with different types of self-expanding neurostent assistance in 468 patients. Patient and aneurysm characteristics, pharmacologic therapy protocol, complications, and initial occlusion grades were analyzed. Patients underwent angiographic follow-up at 6 months to 7 years after treatment. DSA or MRA images of all patients were analyzed to assess the occlusion rate of aneurysms and patency of the parent artery. Enterprise (n = 340), Solitaire (n = 98), Wingspan (n = 41), LEO (n = 16), and Neuroform (n = 5) stent systems were used in this series. Stent-related thromboembolic events occurred in 21 patients and intraoperative rupture occurred in 4 patients. Initially, complete occlusion was achieved in 42.2% of the aneurysms, and, according to the last follow-up data, the rate had progressed to 90.8%. Recanalization rate at 6 months was 8%, whereas the late recanalization rate was 2%. The use of stents in endovascular treatment provides high rates of complete occlusion and low rates of recurrence at a long-term follow-up study.

Rare saccular aneurysm in a medial type persistent trigeminal artery trunk and literature review

We report an extremely rare case of saccular aneurysm in the left medial type persistent trigeminal artery (PTA) trunk and discuss its clinical importance. A 77-year-old woman who had symptom suggestive of vertebrobasilar insufficiency underwent cerebral magnetic resonance (MR) imaging and non-contrast three dimensional time-of-flight MR angiography (3D TOF MRA) using a 3 T scanner. 3D TOF MRA images revealed a left medial type PTA originated from the left internal carotid artery C5 portion, through cavernous sinus and connected to the basilar artery with a saccular aneurysm in the mid portion of its trunk. The basilar artery (BA) under the union was hypoplastic. The bilateral posterior communicating arteries were absent. To our knowledge, this is the first report of a medial type PTA associated with a saccular aneurysm in the PTA trunk. Being aware of this is crucial in clinical, because they can influence surgical and interventional procedures.

E-051 Combination of Contrast Enhanced Time-Resolved 3D MRA and 3D Neuroimaging Software for the Evaluation of Brain Aneurysms Treated with Coil Embolisation

PurposeTo improve the visualisation of residual neck in the aneurysms treated with coil embolisation utilising the time-resolved contrast enhanced magnetic resonance angiography (4D MRA).Materials and MethodsA total of 11 patients...

Non-ECG-gated unenhanced MRA of the carotids: Optimization and clinical feasibility

To optimise and assess the clinical feasibility of a carotid non-ECG-gated unenhanced MRA sequence. Sixteen healthy volunteers and 11 patients presenting with internal carotid artery (ICA) disease underwent large field-of-view balanced steady-state free precession (bSSFP) unenhanced MRA at 3T. Sampling schemes acquiring the k-space centre either early (kCE) or late (kCL) in the acquisition window were evaluated. Signal and image quality was scored in comparison to ECG-gated kCE unenhanced MRA and TOF. For patients, computed tomography angiography was used as the reference. In volunteers, kCE sampling yielded higher image quality than kCL and TOF, with fewer flow artefacts and improved signal homogeneity. kCE unenhanced MRA image quality was higher without ECG-gating. Arterial signal and artery/vein contrast were higher with both bSSFP sampling schemes than with TOF. The kCE sequence allowed correct quantification of ten significant stenoses, and it facilitated the identification of an infrapetrous dysplasia, which was outside of the TOF imaging coverage. Non-ECG-gated bSSFP carotid imaging offers high-quality images and is a promising sequence for carotid disease diagnosis in a short acquisition time with high spatial resolution and a large field of view. • Non-ECG-gated unenhanced bSSFP MRA offers high-quality imaging of the carotid arteries. • Sequences using early acquisition of the k-space centre achieve higher image quality. • Non-ECG-gated unenhanced bSSFP MRA allows quantification of significant carotid stenosis. • Short MR acquisition times and ungated sequences are helpful in clinical practice. • High 3D spatial resolution and a large field of view improve diagnostic performance.

A 29 Year Old Woman with Acute Mental Status Changes

Moyamoya disease is a rare cerebrovascular disease that causes occlusion of the supraclinoid internal carotid arteries and its branches within the Circle of Willis. While rare in the United States and Europe, moyamoya disease is much more common in eastern Asian populations. We present a 29 year-old Caucasian woman who initially presented with severe mental status changes and ataxia. MRI and MRA imaging, as well as pathologic examination at autopsy, revealed occlusion of the middle cerebral and anterior cerebral arteries bilaterally with associated infarctions. This case underscores the importance considering this diagnosis as an etiologic possibility during the workup of multiple infarcts, even in non-Asian populations.

Value of 3-Dimensional High-Resolution Magnetic Resonance Imaging in Detecting the Offending Vessel in Hemifacial Spasm

High-resolution 3-dimensional (3-D) magnetic resonance imaging (MRI) is widely used to predict the neurovascular anatomy within the cerebellopontine angle. To assess the value of 3-D steady-state free precession imaging (SSFP) and time-of-flight magnetic resonance angiography (TOF MRA) in detecting the offending vessels in hemifacial spasm in comparison to intraoperative endoscopic visualization. 42 patients underwent endoscope-assisted microvascular decompression (MVD). All available preoperative 3-D SSFP and TOF MRA images were checked. Intraoperative videos were captured by a high-definition endoscopic camera attached to endoscopes while exploring the area of facial nerve root exit zone (REZ). Evaluation of the 3-D images was performed by 2 independent groups of observers and compared with the operative findings. Three-D MRI had an average positive predictive value (PPV) of 89.1% in differentiating between simple and complex compression. Mean accuracy of the images in detection of the offending vessels was 83.3% and 77% according to the first and second groups of observers, respectively. Averaged inter-observer agreement between the 2 groups of observers was substantial, with an averaged Kappa coefficient (K) of 0.56. In the simple compression group, mean accuracy was 97% and 89.4% according to the first and second groups of observers, respectively. Averaged K for agreement was substantial (K = 0.65). According to endoscopic visualization, 3-D SSFP and TOF MRA images are accurate in detecting the offending vessels in simple compression of the facial nerve, and in predicting presence of a complex compression with variable sensitivity in identifying all offending vessels.

Educational Exhibit Abstract No. 337 - Blood pool MRI contrast agent use in pediatric patients for vascular imaging

Learning Objectives We review the imaging technique, discuss advantages/disadvantages, and provide examples of cases where blood pool (BP) contrast MRI may provide new options for pediatric disease detection and monitoring. Background BP contrast agents are a relatively new and promising option in the MR assessment of disease, but currently the experience and published/recognized indications for the use of these agents are limited in the pediatric population. Gadofoveset trisodium (Ablavar) binds reversibly to albumin causing a prolonged BP residence and increasing T1 shortening. Although aortoiliac disease in adults is currently the only FDA-approved indication, other potential applications for BP agents are under investigation. Compared to traditional MRA, BP agents allow for both arterial and venous phase imaging, as well as delayed venous imaging independent of bolus timing. This enables repeat imaging without re-injection, covering a larger anatomic area, e.g. head to foot, if necessary. Clinical Findings/Procedure Details We retrospectively reviewed all MRI studies performed at our institution in children using Ablavar over the past 12 months. After dynamic arterial and early venous phase imaging, delayed venous imaging was performed with high resolution SPGR or MRA imaging with combined respiratory and ECG gating, reconstructed into orthogonal planes. Patient demographic, clinical history, exam indication, MRI technique, and imaging findings as they pertained to dynamic MRA and BP imaging were recorded. The most common indication for utilization of BP contrast agent in our population was for pediatric venography (n=9/22). Other indications included evaluation of liver vessel patency/anatomy (n=7), vasculitis (n=2), acute GI bleeding (n=2), vascular supply of an intra-abdominal mass (n=1), and for refractory hypertension (n=1). Conclusion and/or Teaching Points Blood pool MRI contrast agents can be extremely useful in pediatric imaging for certain indications, particularly for high-resolution venous imaging covering a large area. Optimization of technique and understanding BP imaging benefits/limitations are fundamental to performing an exam with excellent image quality that provides a high degree of diagnostic confidence.

ASSA13-14-12 Association of Renal Artery Variations and Renal Artery Stenosis, Impaired Renal Function, Plasma Renin Activity

<h3>Objectives</h3> To compare the prevalence of hemodynamically significant stenosis between renal arteries with and without variations in resistant hypertensive patients, and to determine whether aberrant renal arteries are associated with higher renin activity and impaired renal function in essential hypertensive patients. <h3>Methods</h3> 292 consecutive resistant hypertensives (212 male and 80 female, mean age 47.4 ± 15.7 yrs) underwent renal artery CTA or MRA to screen for secondary hypertension, two blinded readers evaluated CTA and MRA images for the presence of aberrant renal arteries and hemodynamically significant renal artery stenosis ( &gt; 50%), and discrepancies were resolved by consensus reading. For all the patients, blood samples were collected in the morning after been out of bed for at least 2 h to assess plasma renin activity and aldosterone level, GFR was measured by 99mTc-DTPA to assess bilateral renal function. <h3>Results</h3> A single renal artery was present in both kidneys in 76.4% of the patients. Renal artery variations were found in 23.6% of the cases, including multiple renal arteries in 0.7%, accessory renal arteries in 21.9%, and early division in 2.0%. There was no difference in the prevalence of significant renal artery stenosis between patients with and without aberrant renal arteries (23.3% vs, 22.4%, P = 0.87). For patients with aberrant renal arteries, there was no difference in the prevalence of renal artery stenosis between renal arteries with and without variations (13.0% vs, 11.6%, P = 0.71). Among the patients diagnosed with essential hypertension, 53/226(23.5%) were with renal artery variations, 173/226 (76.5%) were not. Aldosterone level (log-transformed) was similar between these two groups (219.4 ± 116.5 pg/ml vs. 211.1 ± 153.6 pg/ml, P = 0.58). However, plasma renin activity was slightly higher in the former group (3.52 ± 2.42 ng/ml·h vs. 3.19 ± 2.74 ng/ml·h, P = 0.02). Self-paired t-test revealed that there was no difference in GFR between kidneys supplied by renal arteries with and without variations (46.9 ± 10.8 vs. 45.0 ± 11.8, P = 0.29). <h3>Conclusions</h3> Renal artery variations are not associated with higher susceptibility to developing renal artery stenosing lesions and impaired renal function. Essential hypertensives with aberrant renal arteries are prone to have high plasma renin activity.

Normal Flow Signal of the Pterygoid Plexus on 3T MRA in Patients without DAVF of the Cavernous Sinus

Cavernous sinuses and draining dural sinuses or veins are often visualized on 3D TOF MRA images in patients with dural arteriovenous fistulas involving the CS. Flow signals may be seen in the jugular vein and dural sinuses at the skull base on MRA images in healthy participants, however, because of reverse flow. Our purpose was to investigate the prevalence of flow signals in the pterygoid plexus and CS on 3T MRA images in a cohort of participants without DAVFs. Two radiologists evaluated the flow signals of the PP and CS on 3T MRA images obtained from 406 consecutive participants by using a 5-point scale. In addition, the findings on 3T MRA images were compared with those on digital subtraction angiography images in an additional 171 participants who underwent both examinations. The radiologists identified 110 participants (27.1%; 108 left, 10 right, 8 bilateral) with evidence of flow signals in the PP alone (n = 67) or in both the PP and CS (n = 43). Flow signals were significantly more common in the left PP than in the right PP. In 171 patients who underwent both MRA and DSA, the MRA images showed flow signals in the PP with or without CS in 60 patients; no DAVFs were identified on DSA in any of these patients. Flow signals are frequently seen in the left PP on 3T MRA images in healthy participants. This finding may be the result of flow reversal and should not be considered to indicate occult DAVF.

Comparison of contrast‐enhanced multi‐station MR angiography and digital subtraction angiography of the lower extremity arterial disease

To compare diagnostic accuracy of multi-station, high-spatial resolution contrast-enhanced MR angiography (CE-MRA) of the lower extremities with digital subtraction angiography (DSA) as the reference standard in patients with symptomatic peripheral arterial occlusive disease. Of 485 consecutive patients undergoing a run-off CE-MRA, 152 patients (86 male, 66 female; mean age, 71.6 years) with suspected peripheral arterial occlusive disease were included into our Institutional Review Board approved study. All patients underwent MRA and DSA of the lower extremities within 30 days. MRA was performed at 1.5 Tesla with a single bolus of 0.1 mmol/kg body weight of gadobutrol administered at a rate of 2.0 mL/s at three stations. Two readers evaluated the MRA images independently for stenosis grade and image quality. Sensitivity and specificity were derived. Sensitivity and specificity ranged from 73% to 93% and 64% to 89% and were highest in the thigh area. Both readers showed comparable results. Evaluation of good and better quality MRAs resulted in a considerable improvement in diagnostic accuracy. Contrast-enhanced MRA demonstrates good sensitivity and specificity in the investigation of the vasculature of the lower extremities. While a minor investigator experience dependence remains, it is standardizable and shows good inter-observer agreement. Our results confirm that the administration of Gadobutrol at a standard dose of 0.1 mmol/kg for contrast-enhanced runoff MRA is able to detect hemodynamically relevant stenoses. Use of contrast-enhanced MRA as an alternative to intra-arterial DSA in the evaluation and therapeutic planning of patients with suspected peripheral arterial occlusive disease is well justified.

Can 3T MR Angiography Replace DSA for the Identification of Arteries Feeding Intracranial Meningiomas?

For identifying the arterial feeders of meningiomas, the usefulness of 3D TOF MRA at 3T has not been systematically investigated. This study was intended to assess whether unenhanced 3D TOF MRA at 3T can replace DSA for the identification of arteries feeding intracranial meningiomas and whether it is useful for assessing their dural attachment. Twenty-one consecutive patients with intracranial meningiomas (18 women, 3 men; aged 42-77 years, mean 57 years) underwent DSA, conventional MR imaging, and 3D TOF MRA. Two neuroradiologists independently evaluated the primary and secondary feeders of each tumor on maximum-intensity-projection and source MRA images. They also identified the location of dural attachments based on information from MR imaging/MRA images. Interobserver and intermodality agreement was determined by calculating the κ coefficient. For the identification of primary and secondary feeders on MRA images, interobserver agreement was very good (κ=0.83; 95% CI, 0.66-1.00) and moderate (κ=0.58; 95% CI, 0.34-0.82) and intermodality agreement (consensus reading of MRA versus DSA findings) was excellent (κ=0.94; 95% CI, 0.84-1.00) and good (κ=0.72; 95% CI, 0.51-0.93), respectively. With respect to the dural attachment of meningiomas, interobserver agreement was very good (κ=0.95; 95% CI, 0.84-1.00). The agreement in the diagnosis between MR imaging/MRA and surgery was excellent (κ=1.00). Unenhanced 3D TOF MRA at 3T cannot at present supplant DSA for the identification of the feeding arteries of intracranial meningiomas. This information may be useful for evaluating their dural attachment.

Verification of a semi-automated MRI-guided technique for non-invasive determination of the arterial input function in 15O-labeled gaseous PET

A semi-automated MR-guided technique has been evaluated for non-invasive estimation of cerebral metabolic rate of oxygen (CMRO2) using the sequential administration of 15O oxygen (O2) and 15O carbon dioxide (CO2) during a single PET scan. Two mathematical models, which assess the arterial input function (AIF) from time-activity curves (TAC) in the internal carotid artery region, were tested, namely one with a simple correction for the recovery coefficient (RC) and another with corrections for RC and spillover from surrounding tissues. RC was determined from MRA and black-blood image. RC was also determined from C15O blood volume images as a reference. RC agreed between MR-based and C15O-PET based methods, suggesting validity of MR-based methods. Area-under-the-curve (AUC) of the early portion of estimated AIF agreed with that of measured AIF in both models. AUC of the delayed phase of estimated AIF was largely overestimated in the first model, but was sufficiently improved by the spillover correction implemented in the second model.

Measurements of lenticulostriate arteries using 7T MRI: new imaging markers for subcortical vascular dementia

Recent studies have demonstrated that ultra-high resolution MRA imaging using 7 Tessla (T) MRI can be employed to noninvasively visualize the lenticulostriate arteries (LSA) that supply the basal ganglia and internal capsule. Subcortical vascular dementia (SVaD) is believed to involve these regions from an early stage. We investigated whether LSA abnormalities measured by 7T MRA correlate with MRI ischemia markers and neuropsychological/motor deficits. A total of 24 subjects (12 with SVaD, 12 normal controls (NC)) were imaged with 3T and 7T MRIs. We assessed the severity of white matter hyperintensities (WMH) and the number of lacunes and microbleeds (MB) by visually inspecting images obtained from conventional 3T MRI. We also analyzed three-dimensional models of the measured LSAs obtained from 7T MRI. Compared to the NC, the SVaD subjects had fewer branches of LSAs and greater radii of LSAs. The number of branches was correlated with the number of lacunes. The number of branches was correlated with the delayed recall scores on Rey's Complex Figure Test (RCFT). While not quite reaching statistical significance, the immediate recall, recognition scores on the RCFT, recognition scores on the Seoul Verbal Learning Test, and the word and color readings of Stroop trended in the direction of correlation with the number of branches, as well as with the extrapyramidal scores. Our findings suggest that LSA imaging using 7T MRI might be a potent candidate for the detection of SVaD.

MO-D-213CD-01: Cartesian Methods for Rapid Time-Resolved MR Angiography.

1. Understand recently developed physics techniques which have allowed a 20x improvement in the speed of data acquisition for MR angiography 2. Understand how Cartesian sampling of k-space facilitates the practical and effective implementation of these techniques 3. Show how contemporary implementation of these physics techniques has provided a significant improvement in MRA image quality over the last decade.

Analysis of the Influence of 4D MR Angiography Temporal Resolution on Time-to-Peak Estimation Error for Different Cerebral Vessel Structures

Time-resolved MRA imaging is a promising technique for blood flow evaluation in case of cerebrovascular malformations. Unfortunately, 4D MRA imaging is a trade-off between spatial and temporal resolution. The aim of this study was to investigate the influence of temporal resolution on the error associated with TTP estimation from indicator dilution curves derived from different vascular structures. Monte Carlo simulation was performed to compute indicator dilution curves with known criterion standard TTP at temporal resolutions between 0.1 and 5 seconds. TTPs were estimated directly and by using 4 hemodynamic models for each curve and were compared with criterion standard TTP. Furthermore, clinical evaluation was performed by using 226 indicator dilution curves from different vessel structures obtained from clinical datasets. The temporal resolution was artificially decreased, and TTPs were estimated and compared with those obtained at the original temporal resolutions. The results of the clinical evaluations were further stratified for different vessel structures. The results of both evaluations show that the TTP estimation error increases exponentially when one lowers the temporal resolution. TTP estimation by using hemodynamic model curves leads to lower estimation errors compared with direct estimation. A temporal resolution of 1.5 seconds for arteries and 2.5 seconds for venous and arteriovenous malformation vessel structures appears to be reasonable to achieve TTP estimations adequate for clinical application. Different vessel structures require different temporal resolutions to enable comparable TTP estimation errors, which should be considered for achieving a case-optimal temporal and spatial resolution.

“One-stop-shop” cardiac MRI at 3.0T for the detection of coronary artery disease

We present one-stop-shop cardiac MRI findings in a 58-year-old male patient with suspected coronary artery disease (CAD) who was scheduled for a primary diagnostic invasive coronary angiography. The patient was instructed to refrain from any beverage or foods containing caffeine, and antianginal medication within 24 hours before the MRI study. The study was performed on a 3.0T whole-body clinical scanner (MAGNETOM Tim Trio, Siemens Healthcare, Erlangen, Germany) equipped with a 12-element cardiac coil. The one-stop-shop cardiac MRI procedure consisted of four major protocols performed in the following order: 1) cine imaging for assessment of left ventricular function; 2) adenosine gadolinium first-pass imaging for assessment of stress perfusion; 3) coronary MRA for assessment of coronary artery anatomy; and 4) delayed enhancement MRI for assessment of myocardial infarction. After localizer sequences, a FLASH sequence was used for cine imaging. The following sequence parameters were used: TR/TE/flip-angle = 5.00 ms/2.44 ms/13°. The short-axis views were distributed to cover the entire left ventricle and two long-axis views (four- and two-chamber views) were also acquired. Adenosine was then administered intravenously at 140 µg/kg/min with the heart rate and blood pressure monitored. After 3 min of the adenosine infusion, an intravenous bolus injection of 0.05 mmol/kg gadolinium contrast material (Magnevist, Schering, Berlin, Germany) was administered into an antecubital vein on the opposing arm with the use of a power injector (Spectris, Medrad, Indianola, Pennsylvania) at a rate of 4 ml/s, followed by a 20 ml saline flush at 4 ml/s. A SR-Turbo-FLASH sequence was used for perfusion imaging with the following parameters: TR/TE/flip-angle = 2.38/1.14/12°, FOV = 270×360 mm2, matrix = 94×192, spatial resolution = 2.9×1.9×10 mm3, GRAPPA factor = 2, TI = 100 ms, and the number of slices = 3. Whole-heart coronary MRA with additional slow infusion of contrast material (0.15 mmol/kg at 0.3 ml/sec) was acquired after perfusion imaging. A navigator-gated, electrocardiography-triggered, fat saturated, segmented 3D fast low-angle shot sequence [1,2], with the following image parameters was used: TR/TE/flip-angle = 3.0/1.4/20°, readout bandwidth = 610 Hz/pixel, voxel size = 1.3 × 1.3 × 1.3 mm3 interpolated to 0.65 × 0.65 × 0.65 mm3, GRAPPA factor = 2, inversion prepulse delay = 200 ms. Delayed enhancement images were acquired by phase sensitive inversion recovery sequences after coronary MRA for viability study. The total examination time was 33 min. Acquisition time of whole-heart coronary MRA procedure was 9.1 min with a navigator acceptance rate of 34%. Data reformation and analysis were performed on a commercially available workstation (Leonardo, Siemens Healthcare, Erlangen, Germany). Figure 1 shows “one-stop-shop” cardiac MRI images at 3.0T from the 58-year-old male patient with suspected CAD. Figure 1 “One-stop-shop” cardiac MRI images at 3.0T from a 58-year-old male patient with suspected CAD. Perfusion image (A) demonstrates perfusion defects in the mid anteroseptal and inferoseptal segments. Coronary MRA images (B and C) show significant ... This work shows the feasibility of a comprehensive protocol one-stop-shop for cardiac MRI at 3.0T. It is possible to complete the cine imaging, perfusion imaging, coronary MRA, and delayed enhancement imaging in a single study within 35 minutes. The major advantage of this approach is that it offers functional studies for the detection of ischemia, tissue characterization for the detection and quantification of myocardial infarction as well as luminal assessment of the coronary arteries in a single noninvasive and radiation free test. This may be extremely useful for better selecting patients to undergo an invasive procedure. The authors of this manuscript have certified that they comply with the Principles of Ethical Publishing in the International Journal of Cardiology [3].

特異な頭位でめまい・眼振が誘発された延髄腹側嚢胞の1例

We report herein on a case of unique head position-induced dizziness and nystagmus. A 64-year-old man complained of recurrent dizziness during head shaking following hair washing for over 20 years. Because a medullary lesion was suspected at another clinic, he was referred to our university hospital. He showed no cochlear or abnormal neurological symptoms. Routine equilibrium function and neurological tests showed unremarkable findings. A T2-weighted image on brain MRI revealed a high-intensity signal area on the ventral medullary surface. No abnormalities of the vertebral artery were found on MRA imaging and transcranial ultrasonography, namely disappearance, meandering, malformation, or stoppage. On examination, the patient showed down beating nystagmus and dizziness when he bent forward swiftly and shook his head in a sitting position. His nystagmus had a small amplitude and lasted for a few seconds during dizziness. From the MRI findings and a history of Fallot's tetralogy, he was diagnosed as having a congenital neuroenteric cyst. He was followed without any conservative management and surgery because his symptoms disappeared by avoidance of the dizziness-inducing head position. Downbeat nystagmus typically occurs in patients with lesions involving the caudal midline of the cerebellum and the lower brain stem. A distinct vertical head-shaking nystagmus suggests the existence of a central lesion. It is speculated in our case that the unique head position and head shaking caused temporary circulatory disturbance of the cerebellum and the lower brain stem systems.

Fast and Automatically Generation of MIP Image from Brain MRA Images

Fast and Automatically Generation of MIP Image from Brain MRA Images

Abstract 16832: A Protective Role for Toll like Receptor 4 in Pathogen-Mediated Atherosclerosis

Endogenous and exogenous ligands of microbial origin stimulate inflammation associated with atherosclerosis progression via the innate immune Toll like receptors (TLRs). The oral pathogen Porphyromonas gingivalis induces inflammatory oral bone destruction manifested as periodontal disease, a common chronic disease. P. gingivalis-mediated periodontal disease is now recognized as a risk factor for systemic inflammatory diseases including, diabetes, stroke, and atherosclerotic and cardiovascular diseases. We have previously demonstrated that TLR2 deficiency diminished P. gingivalis-mediated atherosclerosis in an ApoE-/-mouse model. In the current study we demonstrate that TLR4 plays a protective role in P. gingivalis induced atherosclerosis. ApoE-/- and Apoe-/-TLR4-/- mice on normal chow diet were orally challenged with P. gingivalis or saline 5 times / week for 3 weeks. Thirteen weeks after the last challenge, plaque and inflammatory cell accumulation was analyzed in aortic tissue. Plaque area (%) and accumulation of macrophages, CD8+ T cells, and IL-17+ cells in aortic plaque were significantly greater in P. gingivalis-infected ApoE-/-TLR4 -/- compared to ApoE-/- mice. TLR4 deficiency was associated with a skewing of the adaptive response to P. gingivalis from a Th1 to a Th17 response with a dysregulation in the production of proinflammatory and immunoregulatory cytokines associated with CD8+ T cell responses. MRA imaging revealed greater luminal narrowing in innominate artery of P. gingivalis-infected ApoE-/- TLR4-/- compared to ApoE-/- mice. Our results are in contrast to studies demonstrating decreased atherosclerosis in ApoE-/-TLR4-/- mice fed a high fat diet. These results support the emerging view that oral bacteria contribute to chronic inflammation at sites distant from infection and establish microbial specific TLR4 signaling as a critical determinant of chronic inflammation associated with atherosclerosis progression.

Accuracy of MRI to identify the coronary artery plaque: A comparative study with intravascular ultrasound

To evaluate the ability of black-blood coronary arterial wall MRI to identify the coronary artery plaque, using intravascular ultrasound (IVUS) as the golden standard. Nineteen consecutive patients underwent IVUS and coronary artery wall MRI. Cross-sectional images were acquired on the lesion of coronary artery from the ostium to the middle segment continuously. The vessel cross-sectional area (CSA), luminal CSA, plaque burden, contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR) were measured in each slice which was then compared with the IVUS images. Sixteen of 19 patients completed coronary artery MRA and wall imaging. 41 of 67 slices were found plaques on both IVUS and MRI; The maximal wall thickness, plaque burden, SNR, CNR in the coronary wall containing plaque were greater compared with the normal coronary wall (1.70 ± 0.51 versus 1.24 ± 0.24; 0.71 ± 0.13 versus 0.59 ± 0.12; 1.86 ± 0.41 versus 1.47 ± 0.23; 5.10 ± 2.21 versus 2.99 ± 1.17; respectively, P < 0.05). The matched MRI and IVUS showed good correlation for vessel CSA (16.77 ± 10.67 versus 16.97 ± 8.36; r = 0.79; P < 0.01), luminal CSA (5.18 ± 5.01 versus 7.13 ± 5.14; r = 0.88; P < 0.01), plaque burden (0.71 ± 0.13 versus 0.59 ± 0.15; r = 0.67; P < 0.01). in segments containing plaques, especially the luminal CSA were strongly correlated. MRI coronary artery wall imaging can identify coronary plaque in the proximal segments. It also has the potential to assess coronary artery size.