MRI in the Evaluation of Cryptogenic Stroke and Embolic Stroke of Undetermined Source.

Cryptogenic stroke refers to a stroke of undetermined etiology. It accounts for approximately one-fifth of ischemic strokes and has a higher prevalence in younger patients. Embolic stroke of undetermined source (ESUS) refers to a subgroup of patients with nonlacunar cryptogenic strokes in whom embolism is the suspected stroke mechanism. Under the classifications of cryptogenic stroke or ESUS, there is wide heterogeneity in possible stroke mechanisms. In the absence of a confirmed stroke etiology, there is no established treatment for secondary prevention of stroke in patients experiencing cryptogenic stroke or ESUS, despite several clinical trials, leaving physicians with a clinical dilemma. Both conventional and advanced MRI techniques are available in clinical practice to identify differentiating features and stroke patterns and to determine or infer the underlying etiologic cause, such as atherosclerotic plaques and cardiogenic or paradoxical embolism due to occult pelvic venous thrombi. The aim of this review is to highlight the diagnostic utility of various MRI techniques in patients with cryptogenic stroke or ESUS. Future trends in technological advancement for promoting the adoption of MRI in such a special clinical application are also discussed.

MR Multitasking-based multi-dimensional assessment of cardiovascular system (MT-MACS) with extended spatial coverage and water-fat separation.

PURPOSE: To extend the MR MultiTasking-based Multidimensional Assessment of Cardiovascular System (MT-MACS) technique with larger spatial coverage and water-fat separation for comprehensive aortocardiac assessment. METHODS: MT-MACS adopts a low-rank tensor image model for 7D imaging, with three spatial dimensions for volumetric imaging, one cardiac motion dimension for cine imaging, one respiratory motion dimension for free-breathing imaging, one T2-prepared inversion recovery time dimension for multi-contrast assessment, and one T2*-decay time dimension for water-fat separation. Nine healthy subjects were recruited for the 3T study. Overall image quality was scored on bright-blood (BB), dark-blood (DB), and gray-blood (GB) contrasts using a 4-point scale (0-poor to 3-excellent) by two independent readers, and their interreader agreement was evaluated. Myocardial wall thickness and left ventricular ejection fraction (LVEF) were quantified on DB and BB contrasts, respectively. The agreement in these metrics between MT-MACS and conventional breath-held, electrocardiography-triggered 2D sequences were evaluated. RESULTS: MT-MACS provides both water-only and fat-only images with excellent image quality (average score = 3.725/3.780/3.835/3.890 for BB/DB/GB/fat-only images) and moderate to high interreader agreement (weighted Cohen's kappa value = 0.727/0.668/1.000/1.000 for BB/DB/GB/fat-only images). There were good to excellent agreements in myocardial wall thickness measurements (intraclass correlation coefficients [ICC] = 0.781/0.929/0.680/0.878 for left atria/left ventricle/right atria/right ventricle) and LVEF quantification (ICC = 0.716) between MT-MACS and 2D references. All measurements were within the literature range of healthy subjects. CONCLUSION: The refined MT-MACS technique provides multi-contrast, phase-resolved, and water-fat imaging of the aortocardiac systems and allows evaluation of anatomy and function. Clinical validation is warranted.

Association of aberrant subclavian arteries with aortic pathology and proposed classification system.

OBJECTIVE: Aberrant subclavian artery (aSCA) is a rare anatomic variant whose association with other aortic branch variations and aortic pathology has yet to be established. Knowledge of such an association could be relevant to recommendations for screening and awareness as associated variations are important for operative planning. We describe the incidence of aSCA variations, its association with aortic pathology, and a proposed classification system. METHODS: The thoracic cross-sectional imaging database at Keck Hospital of the University of Southern California from 2006 to 2018 was queried for presence of aSCA. Studies were evaluated for aSCA laterality, variant anatomy, and aortic and branch vessel disease. Medical records were reviewed for associated symptoms and diagnoses. The primary outcome was association of aSCA with aortic pathology (aneurysm or dissection). Secondary outcomes were comparison of right and left aSCA, comparison between the sexes, and creation of a proposed classification system. RESULTS: Of 98,580 axial imaging studies, 810 studies (0.82%) were identified with aSCA in 312 unique patients. Right aSCA made up the majority of cases (90.1%). All aSCAs had a retroesophageal course. Kommerell's diverticulum (KD) was present in 184 (59%) with an average diameter of 1.67 cm (range, 1.2-3.3 cm). KD was more frequent (84% vs 56%; P = .0003) and larger (2.05 cm vs 1.61 cm; P < .0001) in left aSCA patients. When present, KD was more often symptomatic in left aSCA compared with right aSCA (77.4% vs 49.1%; P = .005). Dysphagia, chest pain, reflux, and asthma were all more common in left aSCA patients. KD was also more common in men (73.3% vs 50%; P < .0001) and larger in men (1.81 cm vs 1.54 cm; P < .0001) but with no difference in symptoms between sexes. Our proposed classification system based on aortic arch branching is as follows: type 1, left arch with right aSCA (59.9%); type 2, left arch with common carotid trunk and right aSCA (30.1%); type 3, right arch with left aSCA (9.6%); and type 4, right arch with common carotid trunk and left aSCA (0.3%). Subtypes describe the right vertebral artery (RVA) and left vertebral artery (LVA) origin: subclavian (s, RVA 90.1%, LVA 96.8%), carotid (c, RVA 9.6%, LVA 0.3%), or arch (a, RVA 0.3%, LVA 2.9%). Overall, 9.9% (31/312) had associated aortic pathology, although the study was underpowered to detect a difference between right aSCA and left aSCA (9.3% vs 16.1%; P = .213). Type 3 and type 4 arches more often have associated aortic pathology, KD, and symptoms. CONCLUSIONS: aSCAs are frequently symptomatic and commonly associated with aortic dissection and aneurysm. Our proposed classification scheme depicts all four aSCA arch variants and accounts for vertebral artery origin variation. These variants are common, and vertebral anatomy can differ greatly. Knowledge of these anatomic variations is critical to planning for endovascular and open repair of aortic arch pathology.

Image Predictors of Treatment Outcome after Thoracic Aortic Dissection Repair.

Treatment of thoracic aortic dissection remains highly challenging and is rapidly evolving. Common classifications of thoracic aortic dissection include the Stanford classification (types A and B) and the DeBakey classification (types I to III), as well as a new supplementary classification geared toward endovascular decision making. By using various imaging techniques, the extent of the dissection, the location of the primary intimal tear, the shape of the aortic arch, and the zonal involvement of the aortic arch-factors that affect the treatment strategy-can easily be identified. Thoracic endovascular aortic repair (TEVAR) is generally performed in two groups of patients: (a) those with a surgically repaired type A dissection, and (b) those with a complicated type B dissection. Several imaging findings can help predict the course of remodeling of the dissected aorta after a repaired type A dissection and TEVAR. A spectrum of imaging findings exist with regard to favorable (positive) or failing (negative) remodeling. A schematic model with imaging support allows the classification of important causes of failing remodeling into proximal and distal groups, on the basis of the origin of the refilling of the false lumen and the underlying pathophysiology of pressurization. Refilling of the false lumen of the aorta after repair of a type A dissection is usually secondary to a persistent intimal tear at the aortic arch, a leak of the distal graft anastomosis, or refilling from the false lumen of a dissected aortic arch vessel. After TEVAR, false lumen refilling is most commonly due to an incomplete seal of the proximal landing related to the aortic tortuosity, an arch branch stump, a supra-arch chimney stent, or the TEVAR technique. Online supplemental material is available for this article. ©RSNA, 2018.

Little League Shoulder in a 15-Year-Old Male Baseball Pitcher.

A 15-year-old baseball pitcher presented to physical therapy with a 1-week history of acute right shoulder pain experienced during the acceleration phase of throwing. The week after physical therapy evaluation, the patient returned with radiographs and magnetic resonance imaging results that revealed lateral physeal widening with adjacent edema. Additionally, a nondisplaced labral tear was noted. In this case, imaging was necessary for an accurate diagnosis of lateral physeal widening, commonly referred to as "Little League shoulder." J Orthop Sports Phys Ther 2018;48(1):51. doi:10.2519/jospt.2018.7369.

Symptomatic Intragraft Thrombus following Endovascular Repair of Blunt Thoracic Aortic Injury.

Thoracic endovascular aortic repair (TEVAR) can be complicated by graft collapse, endoleaks, and stent migration. The incidence of these complications and other outcomes is poorly understood in young trauma victims who receive endovascular aortic repair of blunt thoracic aortic injury (BTAI). A 29-year-old pedestrian was struck by a vehicle resulting in polytrauma including BTAI with transection distal to the left subclavian artery origin. The patient underwent successful TEVAR. Nine months later, the patient developed transient paresthesia below the waist that progressed to bilateral lower extremity paralysis and malperfusion syndrome below the diaphragm including nonpalpable pulses in the lower extremities, acute renal failure, and ischemic colitis. Imaging demonstrated near occlusive thrombosis of the distal end of the thoracic endograft. An emergent axillobifemoral bypass resolved the organ malperfusion and acute limb ischemia. Patients who have undergone TEVAR for BTAI may develop asymptomatic or symptomatic intragraft thrombosis. In patients presenting with malperfusion syndrome below the diaphragm, extra-anatomic bypass can expeditiously resolve symptoms until definitive treatment can be performed. Oversizing of thoracic stents in trauma patient may lead to intragraft thrombosis.

Computerized tomography angiography by direct intra-aortic low volume contrast injection in patients being evaluated for EVAR.

Background Computerized tomography angiography is an important tool for endovascular repair of abdominal aortic aneurysm planning. This study aimed to evaluate the utility of computerized tomography angiography using direct intra-aortic injection of low volume of iodinated contrast in patients being considered for endovascular repair of abdominal aortic aneurysm. Design A 5F high-flow angiographic catheter was positioned in the mid-thoracic aorta through femoral percutaneous access. Computerized tomography angiography was performed with image acquisition starting simultaneously with power injection of 10 mL of iopamidol 76% diluted with normal saline to 50 mL, at 6 mL/s through the angiographic catheter. Aortic enhancement was assessed with a circular region-of-interest within the aorta. Values ≥150 HU were considered adequate. Results Nine patients with abdominal aortic aneurysm and chronic renal dysfunction underwent computerized tomography angiography with intra-arterial contrast injection for endovascular repair of abdominal aortic aneurysm planning. Mean age 78.8 ± 5.0 years, mean baseline creatinine 1.8 ± 0.4 mg/dL and mean glomerular filtration rate 36.8 ± 4.2 mL/min. Adequate computerized tomography angiography aortic enhancement was obtained in all cases (mean intra-aortic density: 300.4 ± 72.8 HU). The total contrast volume used for the computerized tomography angiography and the endovascular repair of abdominal aortic aneurysm combined was 30.0 ± 21.4 mL. Seventy-five percent of the patients received ≤30 mL of contrast. No significant renal function deterioration occurred (creatinine clearance pre- and post-procedure 36.8 ± 4.2 mL/min versus 38.6 ± 6.1 mL/min, p = 0.32). Successful endovascular repair of abdominal aortic aneurysm was achieved in eight patients. One patient underwent open treatment based on computerized tomography angiography information. No endoleak or aneurysm growth occurred (median follow-up: 121 days (range 36-1242)). Conclusion Direct intra-aortic injection of low volume of iodinated contrast provides adequate and reproducible pattern of aortic enhancement on computerized tomography angiography. The computerized tomography angiography so acquired can be used for endovascular repair of abdominal aortic aneurysm limiting the total volume of iodinated contrast required.

High-dose B vitamin supplementation and progression of subclinical atherosclerosis: a randomized controlled trial.

BACKGROUND AND PURPOSE: Although plasma total homocysteine (tHcy) levels are associated with cardiovascular disease, it remains unclear whether homocysteine is a cause or a marker of atherosclerotic vascular disease. We determined whether reduction of tHcy levels with B vitamin supplementation reduces subclinical atherosclerosis progression. METHODS: In this double-blind clinical trial, 506 participants 40 to 89 years of age with an initial tHcy >8.5 micromol/L without diabetes and cardiovascular disease were randomized to high-dose B vitamin supplementation (5 mg folic acid+0.4 mg vitamin B(12)+50 mg vitamin B(6)) or matching placebo for 3.1 years. Subclinical atherosclerosis progression across 3 vascular beds was assessed using high-resolution B-mode ultrasonography to measure carotid artery intima media thickness (primary outcome) and multidetector spiral CT to measure aortic and coronary artery calcium (secondary outcome). RESULTS: Although the overall carotid artery intima media thickness progression rate was lower with B vitamin supplementation than with placebo, statistically significant between-group differences were not found (P=0.31). However, among subjects with baseline tHcy >or=9.1 micromol/L, those randomized to B vitamin supplementation had a statistically significant lower average rate of carotid artery intima media thickness progression compared with placebo (P=0.02); among subjects with a baseline tHcy <9.1 micromol/L, there was no significant treatment effect (probability value for treatment interaction=0.02). B vitamin supplementation had no effect on progression of aortic or coronary artery calcification overall or within subgroups. CONCLUSIONS: High-dose B vitamin supplementation significantly reduces progression of early-stage subclinical atherosclerosis (carotid artery intima media thickness) in well-nourished healthy B vitamin "replete" individuals at low risk for cardiovascular disease with a fasting tHcy >or=9.1 micromol/L.