7T MR of intracranial pathology: Preliminary observations and comparisons to 3T and 1.5T.

PURPOSE: There have been an increasing number of studies involving ultra-high-field 7T of intracranial pathology, however, comprehensive clinical studies of neuropathology at 7T still remain limited. 7T has the advantage of a higher signal-to-noise ratio and a higher contrast-to-noise ratio, compared to current low field clinical MR scanners. We hypothesized 7T applied clinically, may improve detection and characterization of intracranial pathology. MATERIALS AND METHODS: We performed an IRB-approved 7T prospective study of patients with neurological disease who previously had lower field 3T and 1.5T. All patients underwent 7T scans, using comparable clinical imaging protocols, with the aim of qualitatively comparing neurological lesions at 7T with 3T or 1.5T. To qualitatively assess lesion conspicuity at 7T compared with low field, 80-paired images were viewed by 10 experienced neuroradiologists and scored on a 5-point scale. Inter-rater agreement was characterized using a raw percent agreement and mean weighted kappa. RESULTS: One-hundred and four patients with known neurological disease have been scanned to date. Fifty-five patients with epilepsy, 18 patients with mild traumatic brain injury, 11 patients with known or suspected multiple sclerosis, 9 patients with amyotrophic lateral sclerosis, 4 patients with intracranial neoplasm, 2 patients with orbital melanoma, 2 patients with cortical infarcts, 2 patients with cavernous malformations, and 1 patient with cerebral amyloid angiopathy. From qualitative observations, we found better resolution and improved detection of lesions at 7T compared to 3T. There was a 55% raw inter-rater agreement that lesions were more conspicuous on 7T than 3T/1.5T, compared with a 6% agreement that lesions were more conspicuous on 3T/1.5T than 7T. CONCLUSION: Our findings show that the primary clinical advantages of 7T magnets, which include higher signal-to-noise ratio, higher contrast-to-noise ratio, smaller voxels and stronger susceptibility contrast, may increase lesion conspicuity, detection and characterization compared to low field 1.5T and 3T. However, low field which detects a plethora of intracranial pathology remains the mainstay for diagnostic imaging until limitations at 7T are addressed and further evidence of utility provided.

Deep chronic microvascular white matter ischemic change as an independent predictor of acute brain infarction after thoracic aortic replacement.

BACKGROUND: Postoperative brain injury is a cause of mortality and morbidity in patients who undergo thoracic aortic replacement. Chronic microvascular white matter ischemic change (WMIC) has been shown to be associated with acute brain infarction in the general population. WMIC has also been shown to be an independent predictor of non-focal neurocognitive changes, generalized seizures, and temporary neurologic dysfunction in patients who undergo thoracic aortic replacement. The aim of this study is to determine if WMIC is a risk factor for acute brain infarction in patients who undergo thoracic aortic replacement. METHODS: A case-control study of patients who underwent thoracic aortic replacement between 2001 and 2014 were reviewed for neurological changes after surgery and acute brain infarction on postoperative diffusion-weighted imaging (DWI) magnetic resonance imaging (MRI). Patients with neurological changes were matched with control patients who underwent thoracic aortic replacement and had postoperative neurological symptoms without acute brain infarctions. Acute infarction was re-assessed by reviewing DWI sequences on postoperative MRI. WMIC was assessed on FLAIR and T2WI sequences on both preoperative and postoperative MRI. Logistic regression was performed assessing the relationship of WMIC and acute ischemic infarction. RESULTS: 5171 patients underwent thoracic aortic replacement; 179 had postoperative neurological changes, and of those 53 patients had acute brain infarction on postoperative DWI. Patients with deep WMIC were more likely to have acute DWI infarctions after thoracic aortic replacement (P = 0.023). CONCLUSION: Our matched retrospective case-controlled study shows deep WMIC to be a predictor of acute brain infarction on DWI after thoracic aortic replacement.

Vessel wall MR imaging of aortic arch, cervical carotid and intracranial arteries in patients with embolic stroke of undetermined source: A narrative review.

Despite advancements in multi-modal imaging techniques, a substantial portion of ischemic stroke patients today remain without a diagnosed etiology after conventional workup. Based on existing diagnostic criteria, these ischemic stroke patients are subcategorized into having cryptogenic stroke (CS) or embolic stroke of undetermined source (ESUS). There is growing evidence that in these patients, non-cardiogenic embolic sources, in particular non-stenosing atherosclerotic plaque, may have significant contributory roles in their ischemic strokes. Recent advancements in vessel wall MRI (VW-MRI) have enabled imaging of vessel walls beyond the degree of luminal stenosis, and allows further characterization of atherosclerotic plaque components. Using this imaging technique, we are able to identify potential imaging biomarkers of vulnerable atherosclerotic plaques such as intraplaque hemorrhage, lipid rich necrotic core, and thin or ruptured fibrous caps. This review focuses on the existing evidence on the advantages of utilizing VW-MRI in ischemic stroke patients to identify culprit plaques in key anatomical areas, namely the cervical carotid arteries, intracranial arteries, and the aortic arch. For each anatomical area, the literature on potential imaging biomarkers of vulnerable plaques on VW-MRI as well as the VW-MRI literature in ESUS and CS patients are reviewed. Future directions on further elucidating ESUS and CS by the use of VW-MRI as well as exciting emerging techniques are reviewed.

Multimedia article. Successful endoscopic wire-guided balloon dilatation of angulated and tight ileal pouch strictures without fluoroscopy.

BACKGROUND: Ileal pouch strictures that are visually inaccessible by an endoscope may be balloon-dilated by exchange guide wire across the stricture with the aid of fluoroscopy. We present a technique of wire-guided balloon dilation without fluoroscopy to navigate strictures in the ileal pouch. METHODS: A 50-year-old Caucasian female presented with a 24-year history of ulcerative colitis (UC) with restorative proctocolectomy and ileal pouch anal anastomosis (IPAA) for 7 years. She developed Crohn's disease (CD) of the pouch with multiple strictures at the afferent limb of the pouch and a pouch-vaginal fistula. On pouchoscopy, the patient had two strictures at the distal neoterminal ileum, at 10 cm and 15 cm proximal to the pouch inlet. In retrospect, the distal stricture was angulated and 1 cm in length, and the proximal one was ulcerated and pinhole in size, which prevented the passage of an endoscope (9.8-mm single-channel, GIF-H180; Olympus Optical, Tokyo, Japan). The stricture number and locations were confirmed by retrograde water-soluble contrast X-ray. There was great difficulty in negotiating the strictures with balloon dilation and hence concern that blind passage of the balloon into the strictures might induce mucosal trauma or perforation. A controlled radial expansion (CRE) wire-guided balloon dilation catheter (CRE TM Single-Use Wire Guided Balloon Dilator; Boston Scientific Microvasive, Natick, MA) was introduced through the scope. Wire exchange technique was applied with help of our endoscopy nurse (A.O.). The guide wire was passed through the strictures without any resistance under endoscopy view. Subsequently, the balloon was introduced across the strictures, and both were successfully dilated to 16 mm (Videos 1 and 2). RESULTS: The procedure and postprocedure course were uneventful, and patient reported great symptomatic relief. CONCLUSION: Endoscopic guide-wire balloon dilation without fluoroscopic guidance appears to be feasible for CD-related strictures in experienced hands.

Current Clinical Applications of Intracranial Vessel Wall MR Imaging.

Intracranial vessel wall MR imaging (VWI) is increasingly being used as a valuable adjunct to conventional angiographic imaging techniques. This article will provide an updated review on intracranial VWI protocols and image interpretation. We review VWI technical considerations, describe common VWI imaging features of different intracranial vasculopathies and show illustrative cases. We review the role of VWI for differentiating among steno-occlusive vasculopathies, such as intracranial atherosclerotic plaque, dissections and Moyamoya disease. We also highlight how VWI may be used for the diagnostic work-up and surveillance of patients with vasculitis of the central nervous system and cerebral aneurysms.

Vessel Wall MRI Added to MR Angiography in the Evaluation of Suspected Vasculopathies.

BACKGROUND AND PURPOSE: We hypothesized that vessel wall MR imaging (VWI) with 3D-time-of-flight magnetic resonance imaging (3D-TOF-MRA) together increases the ability to detect abnormal intracranial vessel segments compared to 3D-TOF-MRA alone. METHODS: Ninety-three consecutive subjects with a clinical history of suspected vasculopathy imaged with both VWI and 3D-TOF-MRAs were retrospectively reviewed. The 3D-TOF-MRAs were reviewed by two independent neuroradiologists classifying arterial segments as normal or abnormal based on caliber changes. Following a 2-week wash-out period, the 3D-TOF-MRAs with VWI together were re-evaluated for caliber changes and/or vessel wall enhancement. A third neuroradiologist served as consensus. Significance was assessed by McNemar's test. RESULTS: Forty-two subjects with VWI and 3D-TOF-MRAs met the inclusion criteria. By 3D-TOF-MRA alone, 12.3% (95% confidence interval [CI], 10.7-15.1) of the arterial segments were identified as abnormal compared to 20.8% (95% CI, 18.2-23.4) by VWI and 3D-TOF-MRA together (P < .0001). CONCLUSIONS: 3D-TOF-MRA and VWI together identifies a higher number of abnormal vessel segments than 3D-TOF-MRA alone and may provide a more accurate assessment of disease burden.

Feasibility of vessel wall imaging in assessing unruptured paraclinoid aneurysms: Clinical observations and preliminary experience.

INTRODUCTION: The determination of the precise location of unruptured paraclinoid aneurysms with respect to the dura is essential in order to establish the risk of subarachnoid hemorrhage (SAH). In equivocal cases, current imaging modalities are often limited when trying to distinguish the precise relationship of these aneurysms with respect to the dura. We assessed the utility of vessel wall magnetic resonance (VW-MR) imaging in identifying the definitive location of unruptured paraclinoid aneurysms. METHODS: We performed an observational retrospective review using a prospective database of patients undergoing 3T VW-MR of the brain. We included patients that underwent VW-MR gadolinium-enhanced T1-weighted black-blood sequences with fat suppression and saturation band to evaluate unruptured paraclinoid region aneurysms. The dural locations of the aneurysms were first identified on DSA or TOF-MRA and subsequently with VW-MR. The location of aneurysms on VW-MR were then compared qualitatively with the reference standard DSA/TOF-MRA by 2 neurovascular imaging experts. RESULTS: Fifteen patients with unruptured paraclinoid region aneurysms were imaged with VW-MR. The extradural or intradural locations of the aneurysms were determined in 80% of patients using VW-MR compared to 47% with DSA/MRA. CONCLUSIONS: VW-MRI may be a feasible imaging technique for identifying the extradural or intradural location of unruptured paraclinoid aneurysms and may help guide management. Further larger studies may be warranted.

High resolution vessel wall MR imaging in prestenotic intracranial atherosclerotic disease.

Vessel wall MR imaging (VWI) may be able to highlight vulnerable intracranial atherosclerosis with vessel wall enhancement thereby serving as a biomarker for symptomatic prestenotic intracranial atherosclerotic disease. We present a case of intracranial hemorrhage presumably due to intracranial atherosclerotic disease (ICAD) identified by VWI and silent on lumen-based imaging modalities. A 66-year-old female presented with sudden onset headache and dysarthria. A head CT showed intracranial hemorrhage centered in the right basal ganglia. Further imaging by CT angiography, MR angiography and a conventional catheter angiogram were negative. MRI of the brain, including VWI, showed abnormal enhancement in the right middle cerebral artery vessel wall, suggesting intracranial atherosclerotic changes in a prestenotic vessel. As a potential noninvasive screening test, VWI could impact patients with ICAD and become part of a stroke risk stratification algorithm.

Spatial Distribution of Intracranial Vessel Wall Enhancement in Hypertension and Primary Angiitis of the CNS.

We hypothesized a difference in the spatial distribution of intracranial vessel wall enhancement between CNS vasculitis and risk factors for intracranial atherosclerotic disease (ICAD). Fifty-five vessel wall MR imaging (VWI) exams were included in this retrospective observational study. Intracranial arteries were evaluated for vessel wall enhancement by branching pattern (e.g., primary, secondary, and tertiary segments). Demographic and laboratory data as well as ICAD risk factors, including a diagnosis of hypertension, were collected. A diagnosis of primary angiitis of the CNS (PACNS) was confirmed by biopsy or clinical assessment by a stroke neurologist. Univariate and multivariate Poisson regression models were fit for the outcomes. In multivariate analyses, hypertension showed significant associations with primary (ß = 1.31, 95% CI 0.78-1.88, p < 0.0001) and secondary (ß = 1.15, 95% CI 0.29-2.18, p = 0.05) segments, contrasting with PACNS which showed a distal spatial distribution with significant associations with secondary (ß = 0.77, 95% CI 0.14-1.39, p = 0.05) and tertiary (ß = 1.34, 95% CI 0.68-2.01, p < 0.0001) segments. Our results suggest the spatial distribution of vessel wall enhancement is an important consideration when interpreting VWI exams, particularly in patients with a comorbid diagnosis of hypertension. Given the global prevalence of hypertension, these results are impactful and may improve image interpretation of VWI in stroke patients.

Vessel wall MRI for suspected isolated basilar artery dissection.

Isolated basilar artery dissection is an uncommon intracranial vasculopathy with a poor prognosis. Digital subtraction angiography is considered the definitive modality for diagnosis. Vessel wall MRI (VW-MRI) is an emerging non-invasive technique for assessing the structural integrity of intracranial vessel walls and lumina. Recently, a small number of studies have described the vessel wall patterns of intracranial artery dissection. However, studies on vessel wall imaging of isolated basilar artery dissection remain limited. We describe a patient with suspected isolated spontaneous basilar artery dissection diagnosed using VW-MRI.

Computed tomography correlation of airway disease with bronchoscopy--part II: tracheal neoplasms.

This pictorial essay illustrates, describes, and correlates computed tomographic findings of tracheal neoplasms with fiberoptic bronchoscopy findings. Corresponding computed tomography (CT) and bronchoscopy findings of common primary tracheal neoplasms; squamous cell papilloma, papillomatosis, squamous cell carcinoma, adenoid cystic adenoma, non-Hodgkin׳s lymphoma, and a secondary malignant neoplasm of the trachea; and renal cell carcinoma were correlated.

Computed tomography correlation of airway disease with bronchoscopy: part I--nonneoplastic large airway diseases.

To illustrate and describe computed tomographic large airway pathology and correlate with fiberoptic bronchoscopy findings. Commonly encountered diseases of the large airway include tracheobronchial amyloidosis, tracheobronchopathia osteochondroplastica, tracheobronchomegaly, laryngotracheobronchial papillomatosis, relapsing polychondritis, Wegener granulomatosis, sarcoidosis, and tracheal stenosis. Computed tomography manifestations and bronchoscopic findings of these selected large airway diseases are discussed.

Impact of ileal pouch-anal anastomosis on the surgical outcome of orthotopic liver transplantation for primary sclerosing cholangitis.

BACKGROUND: The definitive treatment for patients with primary sclerosing cholangitis (PSC) is orthotopic liver transplantation (OLT), while the surgical treatment of choice for UC is restorative protocolectomy with ileal pouch-anal anastomosis (IPAA). While studies to date show that OLT may impact the outcome of IPAA, the effect of IPAA on the surgical outcome of OLT is not known. METHODS: All eligible patients (those with PSC and OLT) from our prospectively maintained OLT and Pouch Databases were included. Patient and OLT graft survivals along with surgical outcomes were assessed. Univariable and multivariable analyses were performed. RESULTS: Seventy-nine patients with OLT for PSC were studied, including those with UC (PSC+OLT+UC, n=27) or without UC (PSC+OLT, n=30), and with UC and IPAA (PSC+OLT+UC+IPAA, n=22). In the PSC+OLT+UC group, 23 (85.2%) had UC before OLT and 4 (14.8%) had UC diagnosed after OLT. In the PSC+OLT+UC+IPAA group, 9 (40.9%) had IPAA-then-OLT and 13 (59.1%) had OLT-then-IPAA, while 21 (95.5%) had UC before OLT and 1 (4.5%) had UC diagnosed after OLT. Kaplan-Meier survival curve showed no statistical differences in patient and graft survivals between the 3 groups. In univariable analysis, there was no statistical difference for acute and chronic rejection, hepatic artery thrombosis, stricture, bile leak and acute and chronic renal failure for the 3 groups. In multivariable analysis, no factors were found to be associated with bacteremia or intra-abdominal abscess. CONCLUSIONS: The presence of the IPAA in OLT for PSC patients appears not to have a negative impact on patient and graft survivals and post-operative complications.