Flip Angle Evolutions Sequence Research Articles

Detection of Reduced Diameter of the Cochlear Nerve in Long-term Deaf Patients Quantified With Semiautomatic Measurement of Nerve Cross-sectional Area Using 3T MRI Data.

High-resolution parallel transmit T2 sampling perfection with application optimized contrast using different flip angle evolution sequence with improved edge discrimination and semiautomatic determination of nerve cross-sectional area (CSA) can be used to evaluate nerve degeneration in the inner auditory canal (IAC) in long-term deaf patients. In patients with hearing loss, temporal bone MRI is routinely acquired to evaluate the morphology of the nerves within the IAC. Earlier studies have shown that the diameter of the cochlear nerve can be used as prognostic marker for the auditory performance after cochlear implantation in postlingually deaf patients. Eighty-two consecutive MRI scans were analyzed using a semiautomatic tool to measure CSA of cranial nerves in the IAC. Results were correlated with patient history and audiology testing as well as with age and gender. There was a significant reduced CSA of the cochlear nerve in ears with moderate-to-profound hearing loss and deafness compared with ears with normal hearing, but no significant difference in ears with mild-to-moderate hearing loss compared with normal hearing. In detail, normal hearing ears had a CSA of 1.23 ± 0.11 mm2, whereas ears with pantonal hearing loss of more than 40 dB had 1.02 ± 0.05 mm2 (P = 0.026). Maximal CSA of the facial nerve was not different among all groups (average, 1.04 mm2 ± 0.03; linear regression, P = 0.001) and stable with age. However, vestibular nerve CSA decreased significantly with age (average, 1.78 ± 0.05 mm2; linear regression, P = 0.128). In long-term deaf patients, smaller the diameter of cochlear nerve is the more severe the hearing loss is. The new semiautomatic tool can primarily be used to assess nerve diameter and possibly determine ears with nerve degeneration.

Missing perilymph but leaking blood-endolymph and vestibulocochlear nerve barriers in idiopathic sudden sensorineural hearing loss: A case study

ObjectivesTo evaluate the pathological changes in the blood-perilymph, blood-endolymph, and blood-nerve barriers of a patient with idiopathic sudden sensorineural hearing loss (SSNHL). MethodsPotential ossification or fibrosis in the inner ear was evaluated using temporal bone CT and MRI acquired using the 3-dimensional T2-weighted sampling perfection with application-optimized contrasts using a flip angle evolution sequence. Pathological changes in the barriers were analyzed by MRI obtained 4 h after a single-dose intravenous injection of gadolinium chelate using a medium inversion-time inversion recovery imaging with magnitude reconstruction sequence. ResultsThe perilymph was absent, while significant enhancements of the vestibulocochlear nerve and the endolymphatic compartments were detected. ConclusionSignificant injuries in the blood-endolymph and blood-vestibulocochlear nerve barriers and disabled perilymph production may contribute to the development of SSNHL with poor response to treatments.

Detection and Characteristics of Temporal Encephaloceles in Patients with Refractory Epilepsy.

Temporal encephaloceles are increasingly visualized during neuroimaging assessment of individuals with refractory temporal lobe epilepsy, and their identification could indicate an intracranial abnormality that may be related to a potential seizure focus. Careful review by an experienced neuroradiologist may yield improved detection of TEs, and other clinical, neurophysiologic, and radiologic findings may predict their presence. Data were reviewed retrospectively in patients at our institution who were presented at a multidisciplinary conference for refractory epilepsy between January 1, 2010, and December 31, 2016. Clinical, neurophysiologic, and imaging data were collected. An expert neuroradiologist reviewed the latest MR imaging of the brain in patients for whom one was available, noting the presence or absence of temporal encephaloceles as well as other associated imaging characteristics. A total of 434 patients were reviewed, 16 of whom were excluded due to unavailable or poor-quality MR imaging. Seven patients had temporal encephaloceles reported on initial imaging, while 52 patients had temporal encephaloceles identified on expert review. MR imaging findings were more often initially normal in patients with temporal encephaloceles (P < .001), and detection of temporal encephaloceles was increased in patients in whom 3T MR imaging was performed (P < .001), the T2 sampling perfection with application-optimized contrasts by using different flip angle evolutions sequence was used (P < .001), or the presence of radiologic findings suggestive of idiopathic intracranial hypertension was noted. Seizure onset by scalp electroencephalogram among patients with temporal encephaloceles was significantly more likely to be temporal compared with patients without temporal encephaloceles (P < .001). A significant correlation between intracranial electroencephalogram seizure onset and patients with temporal encephaloceles compared with patients without temporal encephaloceles was not observed, though there was a trend toward temporal-onset seizures in patients with temporal encephaloceles (P = .06). Careful review of MR imaging in patients with refractory temporal lobe epilepsy by a board-certified neuroradiologist with special attention paid to a high-resolution T2 sequence can increase the detection of subtle temporal encephaloceles, and certain clinical and neurophysiologic findings should raise the suspicion for their presence.

Comparative analysis of spherical and fusiform choledochal cyst based on three-dimensional magnetic resonance cholangiopancreatography, biliary amylase, and histopathological examination.

Aims:The aim was to compare biliary amylase, common channel, and gall bladder/liver histopathology between spherical and fusiform choledochal cysts.Materials and Methods:Children undergoing cyst excision with Roux-en-Y hepatico-jejunostomy over a 17 months period were prospectively studied. The common channel was assessed by three-dimensional (3D) magnetic resonance cholangiopancreatography (MRCP).Results:Among 22 patients (spherical = 10, fusiform = 12), there was a higher incidence of spherical cysts in infants (5/7-71.4%) and fusiform cysts in older children (10/15-66.7%) (P = 0.09). Common channel identified in 14 (64%) cases was long (>10 mm) in 5 (38.2%) (one spherical, four fusiform [P = 0.5]) with associated high biliary amylase levels (>500 IU/L) in four (one spherical, three fusiform) (P = 0.05). Exact point of junction of common bile duct with pancreatic duct was visible with coronal half-Fourier-acquisition single-shot turbo spin-echo and 3D sampling perfection with application with optimize contrast using different flip angle evolution sequence using a reformatted plane of axis, particularly coronal, and coronal oblique orientation. Biliary amylase was raised (>100 IU/L) in 4 (40%) in the spherical group, compared to 8 (67%) in the fusiform group. Mean biliary amylase was similar in gallbladder and cyst in spherical but higher in gallbladder in fusiform cysts. Mean biliary amylase was <500 IU/L in 85.7% infants. Five out of 7 infants had liver fibrosis or cirrhosis on histopathology (P = 0.05). There were no dysplastic changes in the gallbladder epithelium.Conclusion:Three-dimensional MRCP delineated the common channel in two-third cases especially in coronal and coronal oblique orientation. The long common channel may have an etiological role in fusiform cysts. Spherical cysts, especially in infants, have a higher incidence of obstructive cholangiopathy.

Three-dimensional sampling perfection with application-optimised contrasts using a different flip angle evolutions sequence for routine imaging of the spine: preliminary experience

The bulk of spinal imaging is still performed with conventional two-dimensional sequences. This study assesses the suitability of three-dimensional sampling perfection with application-optimised contrasts using a different flip angle evolutions (SPACE) sequence for routine spinal imaging. 62 MRI examinations of the spine were evaluated by 2 examiners in consensus for the depiction of anatomy and presence of artefact. We noted pathologies that might be missed using the SPACE sequence only or the SPACE and a sagittal T(1) weighted sequence. The reference standards were sagittal and axial T(1) weighted and T(2) weighted sequences. At a later date the evaluation was repeated by one of the original examiners and an additional examiner. There was good agreement of the single evaluations and consensus evaluation for the conventional sequences: κ>0.8, confidence interval (CI)>0.6-1.0. For the SPACE sequence, depiction of anatomy was very good for 84% of cases, with high interobserver agreement, but there was poor interobserver agreement for other cases. For artefact assessment of SPACE, κ=0.92, CI=0.92-1.0. The SPACE sequence was superior to conventional sequences for depiction of anatomy and artefact resistance. The SPACE sequence occasionally missed bone marrow oedema. In conjunction with sagittal T(1) weighted sequences, no abnormality was missed. The isotropic SPACE sequence was superior to conventional sequences in imaging difficult anatomy such as in scoliosis and spondylolysis. The SPACE sequence allows excellent assessment of anatomy owing to high spatial resolution and resistance to artefact. The sensitivity for bone marrow abnormalities is limited.

Review of the principal extra spinal pathologies causing sciatica and new MRI approaches

In this paper we illustrate the principal extraspinal pathologies causing sciatica and new approaches for the study of structures such as the lumbosacral plexus (LSP). Visualisation of the LSP in its entirety is difficult with conventional two-dimensional MRI sequences owing to its oblique orientation. In our institution, we have found that the utilisation of three-dimensional short tau inversion-recovery sampling perfection with application-optimised contrasts using different flip angle evolutions sequence is helpful, allowing multiplanar and maximum intensity projection reconstructions in the coronal oblique plane and curvilinear reformats through the plexus. Diffusion tensor imaging enables the observation of microstructural changes and can be useful in surgical planning. The normal anatomy of the LSP, its different extraspinal pathologies and differential diagnoses are thoroughly presented.

Dynamic Magnetic Resonance Imaging of the Cervical Spine with High-Resolution 3-Dimensional T2-Imaging

Imaging of the cervical spine in functional positions has so far been limited to conventional X-ray examinations or the scarcely available open magnetic resonance imaging (MRI). An MRI compatible positioning device allows MRI examinations in various positions and even in motion. In combination with high-resolution T2-weighted MRI it allows detailed functional imaging of the cervical spine and nerve roots. To evaluate the utility of this method a population of patients from a clinical study was examined 5 years after anterior cervical discectomy and fusion (ACDF). A total of 32 patients (median age 51.5 years, 15 female, 17 male) were examined after a median interval of 64.3 months from ACDF including 16 patients with a titanium cage and 16 with autologous bone graft. The prototype of an MR compatible positioning device (NeuroSwing) was used for MRI of the cervical spine in functional positions on a 1.5 T MRI unit (Siemens Avanto). A real-time true fast imaging with steady-state precession (FISP) sequence [6 mm, TR 704, TE 1.3 ms, matrix 256 x 207, field of view (FoV) 22 cm] was used for monitoring of flexion up to 45° and extension up to 40° or until patient discomfort. A sagittal T2 sampling perfection with application optimized contrast using different flip angle evolution sequence (SPACE sequence, 0.9 mm isotropic voxels, TR 1770, TE 186 ms, matrix 320 x 318, FoV 28 cm) and an axial true FISP sequence (3 mm slices, TR 194, TE 1.9 ms, matrix 256 x 256, FoV 22 cm) were used for imaging in the end positions. Using the motorized positioning device and a real-time true FISP sequence, imaging of the cervical spine in flexion and extension motion was possible in a quality suitable to observe changes in the alignment of vertebral bodies, the width of the spinal canal and the spinal cord itself. The 3D T2-weighted SPACE sequence yielded high quality and resolution images in the maximum flexion and extension positions. Compared to primary axial T2 true FISP slices, axial reconstructions of the T2 SPACE sequence were found to be clearly less affected by metal artifacts with the additional benefit of multiplanar and transforaminal reconstructions. The combination of a mechanical positioning device and a high-resolution 3D T2-weighted sequence (SPACE) on a conventional 1.5 T MRI allows kinematic imaging of the cervical spine as well as high-resolution imaging in the end positions, even in the presence of metal implants. In this proof of concept study a good visualization of narrowing of the spinal canal in functional positions could be achieved, showing the potential of MRI in functional positions for clinical and research applications.

Evaluation of Aqueductal Stenosis by 3D Sampling Perfection with Application-Optimized Contrasts Using Different Flip Angle Evolutions Sequence: Preliminary Results with 3T MR Imaging

Diagnosis of AS and periaqueductal abnormalities by routine MR imaging sequences is challenging for neuroradiologists. The aim of our study was to evaluate the utility of the 3D-SPACE sequence with VFAM in patients with suspected AS. PC-MRI and 3D-SPACE images were obtained in 21 patients who had hydrocephalus on routine MR imaging scans and had clinical suspicion of AS, as well as in 12 control subjects. Aqueductal patency was visually scored (grade 0, normal; grade 1, partial obstruction; grade 2, complete stenosis) by 2 experienced radiologists on PC-MRI (plus routine T1-weighted and T2-weighted images) and 3D-SPACE images. Two separate scores were statistically compared with each other as well as with the consensus scores obtained from general agreement of both radiologists. There was an excellent correlation between 3D-SPACE and PC-MRI scores (κ = 0.828). The correlation between 3D-SPACE scorings and consensus-based scorings was higher compared with the correlation between PC-MRI and consensus-based scorings (r = 1, P < .001 and r = 0.966, P < .001, respectively). 3D-SPACE sequence with VFAM alone can be used for adequate and successful evaluation of the aqueductal patency without the need for additional sequences and examinations. Noninvasive evaluation of the whole cranium is possible in a short time with high resolution by using 3D-SPACE.

Initial feasibility of a multi‐station high resolution three‐dimensional dark blood angiography protocol for the assessment of peripheral arterial disease

To evaluate the feasibility of a multi-station three dimensional (3D) T1-weighted turbo spin echo (TSE) dark-blood Sampling Perfection with Application optimized Contrasts using different flip angle Evolution sequence (T1w-SPACE), to assess aorta, iliac, and superficial femoral (SFA) arteries (inflow vessels) by comparing it with a multi-station contrast enhanced MR angiography (CE-MRA) with identical resolution. A total of 6 volunteers and 14 peripheral arterial disease (PAD) patients were included in the study. Abdominal and thigh T1w-SPACE and lower leg time-resolved MRA (TR-MRA) with low dose contrast were followed by 3-station CE-MRA. Quantitative measurements of lumen area at 17 locations from T1w-SPACE and CE-MRA were obtained. Additionally, vessel wall areas at the same locations were obtained from the T1w-SPACE images. Quantitative comparison of lumen areas with T1w-SPACE and CE-MRA revealed strong correlation between the two techniques and strong inter-observer agreement for each of the two imaging methods (r > 0.9; P < 0.001). Localized vessel wall area measurements obtained in PAD patients were significantly greater compared with those obtained in normal volunteers (mean difference 43.75 +/- 12.46 mm(2); P < 0.001). Stenosis severity obtained from T1w-SPACE localized measurements showed significant arterial area stenosis in PAD patients. T1w-SPACE imaging of inflow vessels is feasible, and in addition to CE-MRA has the ability to assess atherosclerotic plaque and vascular remodeling.