Contrast-enhanced Magnetic Resonance Angiography Research Articles

Imaging follow-up strategy after endovascular treatment of Intracranial aneurysms: A literature review and guideline recommendations.

Endovascular coil embolization is the primary treatment modality for intracranial aneurysms. However, its long-term durability remains of concern, with a considerable proportion of cases requiring aneurysm reopening and retreatment. Therefore, establishing optimal follow-up imaging protocols is necessary to ensure a durable occlusion. This study aimed to develop guidelines for follow-up imaging strategies after endovascular treatment of intracranial aneurysms. A committee comprising members of the Korean Neuroendovascular Society and other relevant societies was formed. A literature review and analyses of the major published guidelines were conducted to gather evidence. A panel of 40 experts convened to achieve a consensus on the recommendations using the modified Delphi method. The panel members reached the following consensus: 1. Schedule the initial follow-up imaging within 3-6 months of treatment. 2. Noninvasive imaging modalities, such as three-dimensional time-of-flight magnetic resonance angiography (MRA) or contrast-enhanced MRA, are alternatives to digital subtraction angiography (DSA) during the first follow-up. 3. Schedule mid-term follow-up imaging at 1, 2, 4, and 6 years after the initial treatment. 4. If noninvasive imaging reveals unstable changes in the treated aneurysms, DSA should be considered. 5. Consider late-term follow-up imaging every 3-5 years for lifelong monitoring of patients with unstable changes or at high risk of recurrence. The guidelines aim to provide physicians with the information to make informed decisions and provide patients with high-quality care. However, owing to a lack of specific recommendations and scientific data, these guidelines are based on expert consensus and should be considered in conjunction with individual patient characteristics and circumstances.

Evaluating the diagnostic accuracy of 3D contrast-enhanced magnetic resonance angiography versus digital subtraction angiography in spinal dural arteriovenous fistulas.

Spinal dural arteriovenous fistulas (SDAVFs) often go undiagnosed, leading to irreversible spinal cord dysfunction. Although digital subtraction angiography (DSA) is the gold standard for diagnosing SDAVF, DSA is invasive and operator dependent, with associated risks. MR angiography (MRA) is a promising alternative. This study aimed to evaluate the performance of MRA as an equal alternative to DSA in investigating, diagnosing, and localizing SDAVF. Prospectively collected data from a single neurosurgeon at a large tertiary academic center were searched for SDAVFs. Eligibility criteria included any patient with a surgically proven SDAVF in whom preoperative DSA, MRA, or both had been obtained. The eligible patients formed a consecutive series, in which they were divided into DSA and MRA groups. DSA and MRA were the index tests that were compared to the surgical SDAVF outcome, which was the reference standard. Accurate diagnosis was considered to have occurred when the imaging report matched the operative diagnosis to the correct spinal level. Comparisons used a two-sample t-test for continuous variables and Fisher-Freeman-Halton's exact test for categorical variables, with p < 0.05 specifying significance. Univariate, bivariate, and multivariate analyses were conducted to investigate group associations with DSA and MRA accuracy. Positive predictive value, sensitivity, and accuracy were calculated. A total of 27 patients with a mean age of 63 years underwent surgery for SDAVF. There were 19 male (70.4%) and 8 female (29.6%) patients, and the mean duration of symptoms at the time of surgery was 14 months (range 2-48 months). Seventeen patients (63%) presented with bowel or bladder incontinence. Bivariate analysis of the DSA and MRA groups further revealed no significant relationships between the characteristics and accuracy of SDAVF diagnosis. MRA was found to be more sensitive and accurate (100% and 73.3%) than DSA (85.7% and 69.2%), with a subanalysis of the patients with both preoperative MRA and DSA showing that MRA had a greater positive predictive value (78.6 vs 72.7), sensitivity (100 vs 72.7), and accuracy (78.6 vs 57.1) than DSA. In surgically proven cases of SDAVFs, the authors determined that MRA was more accurate than DSA for SDAVF diagnosis and localization to the corresponding vertebral level. Incomplete catheterization at each vertebral level may result in the failure of DSA to detect SDAVF.

Amorphous Albumin Gadolinium-Based Nanoparticles for Ultrahigh-Resolution Magnetic Resonance Angiography.

Magnetic resonance angiography (MRA) contrast agents are extensively utilized in clinical practice due to their capability of improving the image resolution and sensitivity. However, the clinically approved MRA contrast agents have the disadvantages of a limited acquisition time window and high dose administration for effective imaging. Herein, albumin-coated gadolinium-based nanoparticles (BSA-Gd) were meticulously developed for in vivo ultrahigh-resolution MRA. Compared to Gd-DTPA, BSA-Gd exhibits a significantly higher longitudinal relaxivity (r1 = 76.7 mM-1 s-1), nearly 16-fold greater than that of Gd-DTPA, and an extended blood circulation time (t1/2 = 40 min), enabling a dramatically enhanced high-resolution imaging of microvessels (sub-200 μm) and low dose imaging (about 1/16 that of Gd-DTPA). Furthermore, the clinically significant fine vessels were successfully mapped in large mammals, including a circle of Willis, kidney and liver vascular branches, tumor vessels, and differentiated arteries from veins using dynamic contrast-enhanced MRA BSA-Gd, and have superior imaging capability and biocompatibility, and their clinical applications hold substantial promise.

Non-contrast free-breathing 2D CINE compressed SENSE T1-TFE cardiovascular MRI at 3T in sedated young children for assessment of congenital heart disease.

Cardiac MRI is a crucial tool for assessing congenital heart disease (CHD). However, its application remains challenging in young children when performed at 3T. The aim of this retrospective single center study was to compare a non-contrast free-breathing 2D CINE T1-weighted TFE-sequence with compressed sensing (FB 2D CINE CS T1-TFE) with 3D imaging for diagnostic accuracy of CHD, image quality, and vessel diameter measurements in sedated young children. FB 2D CINE CS T1-TFE was compared with a 3D non-contrast whole-heart sequence (3D WH) and 3D contrast-enhanced MR angiography (3D CE-MRA) at 3T in 37 CHD patients (20♂, 1.5±1.4 years). Two radiologists independently assessed image quality, type of CHD, and diagnostic confidence. Diameters and measures of contrast and sharpness of the aorta and pulmonary vessels were determined. A non-parametric multi-factorial approach was used to estimate diagnostic accuracy for the diagnosis of CHD. Linear mixed models were calculated to compare contrast and vessel sharpness. Krippendorff's alpha was determined to quantify vessel diameter agreement. FB 2D CINE CS T1-TFE was rated superior regarding image quality, diagnostic confidence, and diagnostic sensitivity for both intra- and extracardiac pathologies compared to 3D WH and 3D CE-MRA (all p<0.05). FB 2D CINE CS T1-TFE showed superior contrast and vessel sharpness (p<0.001) resulting in the highest proportion of measurable vessels (740/740; 100%), compared to 3D WH (530/620; 85.5%) and 3D CE-MRA (540/560; 96.4%). Regarding vessel diameter measurements, FB 2D CINE CS T1-TFE revealed the closest inter-reader agreement (Krippendorff's alpha: 0.94-0.96; 3D WH: 0.78-0.94; 3D CE-MRA: 0.76-0.93). FB 2D CINE CS T1-TFE demonstrates robustness at 3T and delivers high-quality diagnostic results to assess CHD in sedated young children. Its ability to function without contrast injection and respiratory compensation enhances ease of use and could encourage widespread adoption in clinical practice.

Equilibrium phase contrast-enhanced magnetic resonance angiography of the thoracic aorta and heart using balanced T1 relaxation-enhanced steady-state

BackgroundThree-dimensional (3D) contrast-enhanced MR angiography (CEMRA) is routinely used for vascular evaluation. With existing techniques for CEMRA, diagnostic image quality is only obtained during the first pass of the contrast agent or shortly thereafter, whereas angiographic quality tends to be poor when imaging is delayed to the equilibrium phase. We hypothesized that prolonged blood pool contrast enhancement could be obtained by imaging with a balanced T1 relaxation-enhanced steady-state (bT1RESS) pulse sequence, which combines 3D balanced steady-state free precession (bSSFP) with a saturation recovery magnetization preparation to impart T1 weighting and suppress background tissues. An electrocardiographic (ECG)-gated, 2D-accelerated version with isotropic 1.1-mm spatial resolution was evaluated for breath-hold equilibrium phase CEMRA of the thoracic aorta and heart.Main bodyThe study was IRB approved. 21 subjects were imaged using unenhanced 3D bSSFP, time-resolved CEMRA, first pass gated CEMRA, followed by early and late equilibrium phase gated CEMRA and bT1RESS. 9 additional subjects were imaged using equilibrium phase 3D bSSFP and bT1RESS. Images were evaluated for image quality, aortic root sharpness, and visualization of the coronary artery origins, as well as using standard quantitative measures. ResultsEquilibrium phase bT1RESS provided better image quality, aortic root sharpness, and coronary artery origin visualization than gated CEMRA (P<0.05), and improved image quality and aortic root sharpness versus unenhanced 3D bSSFP (P<0.05). It provided significantly larger apparent signal-to-noise and apparent contrast-to-noise ratio values than gated CEMRA and unenhanced 3D bSSFP (P<0.05) and provided ninefold better fluid suppression than equilibrium phase 3D bSSFP. Aortic diameter and main pulmonary artery diameter measurements obtained with bT1RESS and first pass gated CEMRA strongly correlated (P<0.05). Discussion and ConclusionWe found that using bT1RESS greatly prolongs the useful duration of blood pool contrast enhancement while improving angiographic image quality compared with standard CEMRA techniques. Although further study is needed, potential advantages for vascular imaging include eliminating the current requirement for first pass imaging along with better reliability and accuracy for a wide range of cardiovascular applications.

Progress in ultrasmall ferrite nanoparticles enhanced T1 magnetic resonance angiography.

Contrast-enhanced magnetic resonance angiography (CE-MRA) plays a critical role in diagnosing and monitoring various vascular diseases. Achieving high-sensitivity detection of vascular abnormalities in CE-MRA depends on the properties of contrast agents. In contrast to clinically used gadolinium-based contrast agents (GBCAs), the new generation of ultrasmall ferrite nanoparticles-based contrast agents have high relaxivity, long blood circulation time, easy surface functionalization, and high biocompatibility, hence showing promising prospects in CE-MRA. This review aims to comprehensively summarize the advancements in ultrasmall ferrite nanoparticles-enhanced MRA for detecting vascular diseases. Additionally, this review also discusses the future clinical translational potential of ultrasmall ferrite nanoparticles-based contrast agents for vascular imaging. By investigating the current status of research and clinical applications, this review attempts to outline the progress, challenges, and future directions of using ultrasmall ferrite nanoparticles to drive the field of CE-MRA into a new frontier of accuracy and diagnostic efficacy.

Optimal Protocol for Contrast-enhanced Free-running 5D Whole-heart Coronary MR Angiography at 3T.

Free-running 5D whole-heart coronary MR angiography (MRA) is gaining in popularity because it reduces scanning complexity by removing the need for specific slice orientations, respiratory gating, or cardiac triggering. At 3T, a gradient echo (GRE) sequence is preferred in combination with contrast injection. However, neither the injection scheme of the gadolinium (Gd) contrast medium, the choice of the RF excitation angle, nor the dedicated image reconstruction parameters have been established for 3T GRE free-running 5D whole-heart coronary MRA. In this study, a Gd injection scheme, RF excitation angles of lipid-insensitive binominal off-resonance RF excitation (LIBRE) pulse for valid fat suppression and continuous data acquisition, and compressed-sensing reconstruction regularization parameters were optimized for contrast-enhanced free-running 5D whole-heart coronary MRA using a GRE sequence at 3T. Using this optimized protocol, contrast-enhanced free-running 5D whole-heart coronary MRA using a GRE sequence is feasible with good image quality at 3T.

Kiosk 8R-FB-05 - Deep Learning for 3D Segmentation of Left Atrial Structures in Patients with Atrial Fibrillation Using Contrast-enhanced Magnetic Resonance Angiography

Kiosk 8R-FB-05 - Deep Learning for 3D Segmentation of Left Atrial Structures in Patients with Atrial Fibrillation Using Contrast-enhanced Magnetic Resonance Angiography

Ultra-short Echo-time MR Angiography Combined with a Modified Signal Targeting Alternating Radio Frequency with Asymmetric Inversion Slabs Technique to Assess Visceral Artery Aneurysm after Coil Embolization.

Contrast-enhanced CT and MR angiography are widely used for follow-up of visceral artery aneurysms after coil embolization. However, potential adverse reactions to contrast agents and image deterioration due to susceptibility artifacts from the coils are major drawbacks of these modalities. Herein, we introduced a novel non-contrast-enhanced MR angiography technique using ultra-short TE combined with a modified signal targeting alternating radio frequency with asymmetric inversion slabs, which could provide a serial hemodynamic vascular image with fewer susceptibility artifacts for follow-up after coil embolization.

Renal artery stenosis: a single center experience

Objectives: Renal artery stenosis (RAS) is among the most common causes of secondary hypertension. Prevalence of RAS are seen in end-stage renal disease (ESRD) patients with hypertension between 1-10%. In our study, we evaluated the data of patients with RAS who were followed up with medical treatment and stenting. Methods: In our study, patients who were thought to have renal artery stenosis (RAS) with renal artery doppler ultrasonography were scanned with contrast-enhanced Magnetic Resonance Angiography (MRA). Fifty-three patients (10 received medical therapy, 43 applied invasive procedure) who diagnosed with RAS evaluated. Results: Follow-up times were 15 (12-84) months in patients who received medical therapy, and 12 (10-96) months in patients who treated with invasive therapy (p = 0.583). Median ages were 56 (19-74) years in medical treatment group, and 60 (15-77) years in invasive therapy group (p = 0.955). Compared with the beginning of treatment, diastolic hypertension was decreased of 12.5% in invasive treatment group opposite medical therapy group (p = 0.040), so eGFR was increased of 5.94% in invasive treatment group. Conclusions: In recent years, several studies about survival in patients with RAS was observed that there was no significant difference between the medical and invasive treatment. Clinical, laboratory, and individual characteristics should be considered in treatment choice.

Left atrium 4D-flow segmentation with high-resolution contrast-enhanced magnetic resonance angiography.

Atrial fibrillation (AF) leads to intracardiac thrombus and an associated risk of stroke. Phase-contrast cardiovascular magnetic resonance (CMR) with flow-encoding in all three spatial directions (4D-flow) provides a time-resolved 3D volume image with 3D blood velocity, which brings individual hemodynamic information affecting thrombus formation. As the resolution and contrast of 4D-flow are limited, we proposed a semi-automated 4D-flow segmentation method for the left atrium (LA) using a standard-of-care contrast-enhanced magnetic resonance angiography (CE-MRA) and registration technique. LA of 54 patients with AF were segmented from 4D-flow taken in sinus rhythm using two segmentation methods. (1) Phase-contrast magnetic resonance angiography (PC-MRA) was calculated from 4D-flow, and LA was segmented slice-by-slice manually. (2) LA and other structures were segmented from CE-MRA and transformed into 4D-flow coordinates by registration with the mutual information method. Overlap of volume was tested by the Dice similarity coefficient (DSC) and the average symmetric surface distance (ASSD). Mean velocity and stasis were calculated to compare the functional property of LA from two segmentation methods. LA volumes from segmentation on CE-MRA were strongly correlated with PC-MRA volume, although mean CE-MRA volumes were about 10% larger. The proposed registration scheme resulted in visually successful registration in 76% of cases after two rounds of registration. The mean of DSC of the registered cases was 0.770 ± 0.045, and the mean of ASSD was 2.704 mm ± 0.668 mm. Mean velocity had no significant difference between the two segmentation methods, and mean stasis had a 3.3% difference. The proposed CE-MRA segmentation and registration method can generate segmentation for 4D-flow images. This method will facilitate 4D-flow analysis for AF patients by making segmentation easier and overcoming the limit of resolution.

Application of mask images of contrast-enhanced MR angiography to detect carotid intraplaque hemorrhage in patients with moderate to severe symptomatic and asymptomatic carotid stenosis

PurposeCarotid intraplaque hemorrhage (IPH) on MRI predicts stroke. Magnetization-prepared rapid acquisition gradient (MP-RAGE) is widely used to detect IPH. CE-MRA is used routinely to assess stenosis. Initial studies indicated that IPH can be identified on mask images of CE-MRA, while Time-of-Flight (TOF) images were reported to have high specificity but lower sensitivity. We investigated the diagnostic accuracy of detecting IPH on mask images of CE-MRA and TOF. MethodsThirty-six patients with ≥ 50% stenosis enrolled in the ongoing 2nd European Carotid Surgery Trial underwent carotid MRI. A 5-point quality score was used. Inter-observer agreement between two independent readers was determined. The sensitivity and specificity of IPH detection on mask MRA and TOF were calculated with MP-RAGE as a reference standard. ResultsOf the 36 patients included in the current analysis, 66/72 carotid arteries could be scored. The inter-observer agreements for identifying IPH on MP-RAGE, mask, and TOF were outstanding (κ: 0.93, 0.96, and 0.85). The image quality of mask (1.42 ± 0.66) and TOF (2.42 ± 0.66) was significantly lower than MP-RAGE (3.47 ± 0.61). When T1w images were used to delineate the outer carotid wall, very high specificities (>95%) of IPH detection on mask and TOF images were found, while the sensitivity was high for mask images (>81%) and poor for TOF (50–60%). Without these images, the specificity was still high (>97%), while the sensitivity reduced to 62–71%. ConclusionDespite the lower image quality, routinely acquired mask images from CE-MRA, but not TOF, can be used as an alternative to MP-RAGE images to visualize IPH.

Angiographic challenges of spinal dural and epidural arteriovenous fistulas: report on 45 cases.

The localization of the fistula level in spinal dural arteriovenous fistulas (dAVFs) and epidural arteriovenous fistulas (edAVFs) remains a diagnostic challenge. Consecutive patients with spinal dAVFs and edAVFs in the thoracic, lumbar, and sacral regions were included. The primary endpoint was to describe the characteristics of patients who required angiography with multiple catheterizations of segmental arteries (10 or more). Forty-five patients (median age 69years; male 89%; dAVFs, n = 31; edAVFs, n = 14) were included. Spinal dAVFs commonly developed in the thoracic region and edAVFs in the lumbosacral region. Fistulas were predicted at the correct level or plus/minus 2 level in less invasive examinations using multi-detector CT angiography (n = 28/36, 78%) and/or contrast-enhanced MR angiography (n = 9/14, 64%). We encountered diagnostic challenges in the localization of fistulas in 6 patients. They underwent angiography a median of 2 times. In each patient, spinal levels were examined at a median of 25 levels with a median radiation exposure of 3971mGy and 257ml of contrast. Fistulas were finally localized at the high thoracic region (T4-6) in 3 patients, the sacral region (S1-2) in 2, and the lumbar region (L3) in 1. Four patients were diagnosed with edAVFs and 2 with dAVFs. The correlation coefficient between the fistula level and the rostral end of the intramedullary T2 high-signal intensity on MRI was interpreted as none. In patients in whom less invasive examinations failed for fistula localization, high thoracic or sacral AVFs need to be considered.

Diagnosis of spinal dural arteriovenous fistula: a multimodal MRI assessment strategy

To identify more specific screening indicators at magnetic resonance imaging (MRI) for the diagnosis of spinal dural arteriovenous fistulas (SDAVFs) and to determine an efficient diagnostic strategy. This retrospective study analysed clinical and imaging data of patients diagnosed with SDAVF and alternative myelopathy who underwent conventional MRI examinations. Additionally, three-dimensional (3D) T2-weighted sampling perfection with application-optimised contrasts using different flip-angle evolutions (3D-T2-SPACE) and contrast-enhanced magnetic resonance angiography (CE-MRA) data from patients with SDAVF were compared with digital subtraction angiography (DSA) data. The age of onset, perimedullary flow voids (PFV), distribution of lesions, syringomyelia, degree of spinal oedema, and cauda equina disorder (CED) were factors that showed statistically significance in the identification of SDAVF with alternative myelopathy. After controlling for age, gender, PFV, degree of spinal cord swelling, and syringomyelia, the multivariable ordinal logistic regression model showed that the CED sign (OR = 32.46; 95% confidence interval [CI]: 2.47-427.15; p=0.008) was an independent predictor for SDAVF. The diagnostic model constructed using the PFV and CED signs had better diagnostic performance, with an area under the curve of 0.957 (p<0.001), maximum Youden index of 0.844, sensitivity of 92.9%, and specificity of 91.5%. Both 3D-T2-SPACE (77.8%) and CE-MRA (83.3%) sequences had good localisation values for SDAVF. Combining the two imaging examinations had better diagnostic accuracy than that of DSA. CED and PFV on conventional MRI were specific indicators for the diagnosis of SDAVF. To compensate for the lack of fistula localisation on conventional MRI, 3D-T2-SPACE and CE-MRA can be used. Together they complement each other and have good diagnostic potential.

P03.01.A “TO BE SMART” IN FOLLOW-UP AFTER CRANIAL RADIOTHERAPY: REPORT OF TWO CASES

Abstract BACKGROUND Stroke-like Migraine Attacks after Radiation Therapy Syndrome (SMART) is a rare, delayed complication of radiation therapy and its real incidence is unknown. In this study, clinical and treatment features of two cases with clinical and radiological diagnosis of SMART are presented. METHODS Case-1: 49 years old male was diagnosed with grade-3 Oligodendroglioma; after gross total surgery treated with 60 Gy local cranial radiotherapy and temozolomide. Patient presented with acute left-sided weakness and numbness, episodic myoclonic jerking of the left arm and leg, 6 years after treatment. Contrast-enhanced MRI and MR angiography revealed no sign of a recurrent tumor but contrast uptake at right parietooccipital cortical giriform in the lobe of the right temporal lobe on post-contrast images (FLAIR and T1) and an increase in cortical blood volume are observed in perfusion MRI (Figure A-B). The clinical and radiologic diagnosis was SMART syndrome. Pulse dose steroids was planned as the primary treatment, and neurological symptoms was completely disappeared. After 3.5 years of the primary episode, patient re-applied with acute headache, homonymous hemianopsia of the left eye and left sided hemiparesia. Cranial MRI revealed the similar features and after treatment with steroids for 7 days complete radiological and clinical regression was experienced. Case-2: 60 years old female with a right occipital grade-3 oligodendroglioma treated with resection followed by local cranial radiotherapy (60 Gy) and temozolomide chemotherapy. Ten years after the treatment she presented with severe headache, expressive aphasia and homonymous hemianopsia of the left eye. Contrast-enhanced MRI and MR angiography revealed no sign of a recurrent tumor but contrast uptake at right occipital cortical giriform on post-contrast images (FLAIR and T1) and an increase in cortical blood volume are observed in perfusion MRI (Figurec. The diagnosis was SMART syndrome. After one week of steroid treatment she completely recovered. Similar complaints recurred 9 months after the first episode and completely recovered with steroids in one week. Radiological finding disappeared in 2 months. CONCLUSION SMART syndrome represents an acute-onset rare condition which may result in serious consequences if not diagnosed and treated properly. It usualy appears years after cranial radiation therapy. Clinical signs and radiological findings may resemble tumor recurrence and distinction from real tumor progression is essential. Treatment is symptomatic, most patients recover with steroids and radiological signs disappear completely, however SMART episodes may recur during the follow-up which can be treated similarly.

Role of MRI in diagnosis of pulmonary embolism

BackgroundPulmonary embolism (PE) is considered a serious condition and has clinical challenges in diagnosis. Computed tomography pulmonary angiography (CTPA) is considered the gold standard in PE diagnosis. Contrast-enhanced MRA also has a strong useful role in the diagnosis. Our study aims to assess the role of non-contrast MRA in diagnosis of acute pulmonary embolism compared to either CT pulmonary angiography or contrast enhanced MRA.ResultsIn total, 50 patients with PE confirmed by either CTPA or CE-MRA were included in this study. All patients underwent non-contrast MRPA during the three consecutive days after CTPA or at the same examination setting in CE-MRA. The results were compared and statistically analyzed.The mean age of our study group was 47.80 ± 14.01 years. Males represented 56% (28/50) and females 44% (22/50). The per-vessel sensitivity, specificity and accuracy of non-contrast MRPA reached about 100% for each parameter at the level of the pulmonary trunk, main pulmonary and lobar arteries. At the segmental level, sensitivity, specificity, and accuracy reached about 88%, 100%, and 94%, while at the subsegmental level, about 35%, 100%, and 66% respectively. The overall sensitivity, specificity, and accuracy of non-contrast MRPA regardless of the site were 84%, 100%, and 90% respectively.ConclusionsNon-contrast pulmonary MRA has a high sensitivity and specificity in the diagnosis of PE, especially in proximal pulmonary arteries. So, it can be used as an alternative to the CTA and CE-MRA, especially when the CTA and the use of gadolinium are contraindicated.

The importance of MR imaging in the diagnosis and management of acute stroke

<p>In our collaborative project, called MRI First!, every patient arriving with neurological symptoms of acute stroke and without contraindications was examined by MRI. Our aim was to detect the symptomatic lesions, to obtain appropriate information about the brain parenchyma and to analyse parenchymal perfusion and brain vasculature.</p>. <p>The examinations were conduc&shy;ted on a Philips Ingenia 1.5 Tesla scanner with the following protocol: DWI-ADC, FLAIR, T2 FFE/SWI, PWI, and contrast-enhanced MRA. 415 patients were examined between January 2020 and May 2021. 179 patients arrived within-, and 136 patients after 4.5 hours symptoms onset time, while 100 patients had &ldquo;wake-up&rdquo; stroke.</p>. <p>Within the 4.5 hours group, 81 cases had acute ischemic lesion, 48 of them received reperfusion therapy. Acute ische&shy;mic lesion was found in 64 patients in the wake-up stroke group and in 64 in the 4.5-24 hours group. In these groups 10 and 12 patients obtained reperfusion therapy, respectively. Further 117 cases were considered as stroke mimics, in which cases unnecessary intravenous thrombolysis was avoidable.</p>. <p>MRI is accepted as a sensitive diagnostic modality providing detailed information regarding the brain parenchyma, its perfusion and vasculature. Nonetheless, its worldwide utilization in acute stroke is low and further information should be collected&nbsp;on which patient groups would gain the most benefit from acute MR imaging. Our continuous work is aimed at that goal.</p>.

Anatomical predictors of difficult left internal carotid artery navigation in transradial access for neurointervention.

Transradial access (TRA) has received considerable attention in the field of neurointervention owing to its advantages over transfemoral access. However, the difficulty of left internal carotid artery (ICA) navigation under certain anatomical conditions of the aortic arch and its branches is a limitation of right TRA. In this study the authors aimed to investigate the anatomical predictors that impede navigation of the left ICA in right TRA. From January to October 2020, 640 patients underwent transradial angiography at a single institute. Among them, 263 consecutive patients who were evaluated by contrast-enhanced MRA before transradial angiography were included in the study and assigned to success or failure groups according to whether left ICA navigation was possible or not. Several anatomical predictors were investigated to evaluate the correlation of the success of left ICA navigation in right TRA. A higher grade of the aortic arch type (type I vs type III: OR 6.323, p = 0.0171), higher height of the right subclavian artery (OR 1.071, p = 0.0068), narrower turnoff angle of the left common carotid artery (CCA) (OR 0.953, p = 0.0017), wider distance between the innominate artery and the left CCA (OR 1.784, p < 0.0001), steeper angulation of the right subclavian artery (tortuous vs kinking: OR 6.323, p = 0.0066), and steeper angulation of the left CCA (normal vs tortuous: OR 7.453, p = 0.0087; normal vs kinking: OR 51.65, p < 0.0001) were significantly associated with successful navigation of the left ICA. The cutoff value of the height of the right subclavian artery, distance between the innominate artery and the left CCA, turnoff angle of the left CCA, and diameter of the left CCA were 54.83 mm, 4.25 mm, 17°, and 6.05 mm, respectively. Successful left ICA navigation in right TRA was related to the specific vascular geometry of the aortic arch and its branches. Preprocedural evaluation of the anatomical predictors identified in this study may enhance the success rate of left ICA navigation in right TRA.

Automatic vessel segmentation in MR angiography

Abstract Funding Acknowledgements Type of funding sources: None. Background Vessel-to-background contrast (VBC), the ratio of signal intensities (SI) within a vessel segment compared to the surrounding tissue, is an essential objective parameter for assessing image quality in contrast-enhanced MR angiography (CE-MRA) of peripheral arteries. (1–3) Manual evaluation by the measurement of SIs within the vessel and in the surrounding area is labour-intensive and tedious. (2) An algorithm for automatic segmentation of the vessel lumen and background signal reduces the workload significantly. It has already been successfully applied to CE-MRA in peripheral arterial disease (PAD). (3) However, whether this algorithm is equal to a manual evaluation is not yet known. Purpose To compare the manual and automatic evaluation of VBC in CE-MRA in patients with PAD. Methods A patient with suspected peripheral arterial disease underwent first-pass subtraction MRA on a 3T scanner. Region-of-interests (ROIs) were drawn on predefined vessel segments (Figure 1), manually inside and outside the vessel lumen and additionally a comprehensive ROI with the vessel under investigation in the centre. The algorithm segmented the comprehensive ROI into the vessel and background by identifying a seed point for the vessel and then using a flood fill algorithm. The remaining vessel branches were removed in order to approximate the true background signal. SI of the manual and the automatic segmentation were compared to define the VBC using the formula SI lumen - SI background divided by the standard deviation (SD) of the background for both methods. Results 43 vessel segments were evaluated. An example is given in Figure 2 with A) showing an axial view of the right thigh with a comprehensive ROI with the superficial femoral artery in the centre (green), and manual outlining of the lumen (red) and background (blue). Background signal (B1) and vessel lumen (B2) were used to evaluate the manuall values. Automated segmentation with C1) shows the ROI with the femoral artery in the centre. C2) shows the full extent of the vessel as identified by the flood-fill algorithm, and C3) the resulting mask. Background signal was calculated from SIs remaining in C4 after subtraction of the local maximas shown in C5). The mean SI in the vessel lumen was 4171 (standard deviation, SD 954) for the manual evaluation and 5014 (SD 830) for the automatic evaluation (p = 0.001) and in the background 601 (SD 542) for the manual evaluation and 493 (SD 229) for the automatic evaluation ((p = 0.231). The VBC was 10.3 (SD 5.9) for manual evaluation and 12.2 (SD 5.6) for automatic evaluation (p = 0.139). Conclusion Automatic segmentation of vessel lumen and background signal allows assessment of the VBC in CE-MRA in patients with PAD. The mean SI of the vessel lumen tends to be overestimated about 20% by the automatic algorithm. Higher patient numbers are required to further clarify the applicability of this algorithm for image quality evaluation.

Prevalence and Clinical Implications of Incidental Aortic Arch Abnormalities on Contrast-Enhanced Neck MR Angiography: A Single-Center Experience.

Background and Objectives: Vascular abnormalities within the anatomical coverage are frequently encountered in imaging studies. The aortic arch is often overlooked as an anatomical blind spot, especially in neck magnetic resonance (MR) angiography. This study investigated the prevalence of incidental aortic arch abnormalities. We also estimated the potential clinical significance of aortic arch abnormalities as blind spots detected on contrast-enhanced neck MR angiography. Materials and Methods: Between February 2016 and March 2023, 348 patients were identified based on contrast-enhanced neck MR angiography reports. The clinical and radiological characteristics of the patients and the presence of additional imaging studies were assessed. The aortic arch abnormalities and coexisting non-aortic arterial abnormalities were classified into two categories according to their clinical significance. We performed the χ2 test and Fisher's exact test for group comparisons. Results: Of the 348 study patients, only 29 (8.3%) had clinically significant incidental aortic arch abnormalities. Among these 348 patients, 250 (71.8%) and 136 (39%) had intracranial and extracranial abnormalities, respectively; the clinically significant intracranial abnormalities in the two groups were 130 lesions (52.0%) and 38 lesions (27.9%), respectively. In addition, there was a significantly higher tendency of clinically significant aortic arch abnormalities (13/29, 44.8%) in the patients who had clinically significant coexisting non-aortic arterial abnormalities than in the other group (87/319, 27.3%) (p = 0.044). The patient groups with clinically significant intracranial or extracranial arterial abnormalities had higher rates of clinically significant aortic abnormalities (31.0% and 17.2%), but there was no statistical significance (p = 0.136). Conclusions: The incidence of clinically significant aortic arch abnormalities was 8.3% on neck MR angiography, with a significant association between aortic and coexisting non-aortic arterial abnormalities. The findings of this study could improve the understanding of incidental aortic arch lesions on neck MR angiography, which is of crucial clinical importance for radiologists to achieve accurate diagnoses and management.