Fast Imaging Employing Steady-state Acquisition Sequence Research Articles

Abducens Nerve Duplication: Novel Intraoperative and Radiographic Observation of a Rare Anatomical Variant

Abstract Objectives The abducens nerve has a long, serpentine subarachnoid course with complex topographical relationships, rendering abducens nerve palsy the most common ocular motor cranial nerve palsy in adults and second most common in pediatric patients, with anatomical variants reported in the literature. Preoperative awareness of abducens nerve variant anatomy may help prevent inadvertent intraoperative injury. Design This study is a case report with a review of the abducens nerve anatomy and variants. Setting The study setting included outpatient, inpatient, and operating room in the neurosurgery department of a quaternary referral center. Participants The study included a woman in her early 30s with a diagnosis of petrous meningioma. Main Outcome Measures In vivo documentation of a type 3 abducens nerve duplication was carried out. Results A left extended retrosigmoid craniotomy was recommended for the petroclival meningioma resection. Intraoperatively, a complete duplication of the left abducens cisternal segment was encountered and photographed. The left unilateral abducens nerve duplication was confirmed with postoperative volumetric magnetic resonance imaging using the FIESTA (fast imaging employing steady-state acquisition) sequence, revealing the union of the duplicated cisternal abducens nerves into a single trunk from Dorello's canal distally. Conclusions Abducens nerve variants are uncommon, and although reported in the setting of cadaveric dissection, in vivo documentation of them is limited. This case report of an in vivo type 3 abducens nerve duplication with intraoperative photographic and radiographic images highlights the need for clinical awareness to avoid inadvertent intraoperative injury.

Non-Contrast Enhanced Magnetic Resonance Venography Using the Fast Imaging Employing Steady-State Acquisition (FIESTA) Pulse Sequence in Preoperative Evaluation of Liver Donors: Can it Replace CT Venography?

Background: Liver transplantation has now become the preferred treatment for patients with liver failure. Pre-operative assessment of hepatic/portal vein anatomy of donors is necessary for which CT venography is most commonly used but it exposes the donors to huge radiation burden. To avoid this, non-contrast MR venography is the most preferred alternative for evaluation of veins. Objective: To determine diagnostic yield of magnetic resonance venography using Fast Imaging Employing Steady-State Acquisition (FIESTA) pulse sequence in comparison to computed tomography venography for the determination of portal/hepatic venous anatomy of potential liver donors. Methods: Retrospective study was conducted in which the venous phase CT scan and FIESTA (b-SSFP) sequence of 50 potential liver donors between 01-07-2021 and 30-11-2021 were reviewed. The hepatic and portal venous anatomy was reviewed. The assessment comprised the type of portal venous anatomy, the number of prominent tributaries from segment VIII and V of liver having diameter of 4mm or more emptying into the middle hepatic vein and the total number of accessory inferior right hepatic veins from segment VI and VII emptying into inferior vena cava (IVC). Results: With 100% sensitivity and specificity, the FIESTA sequence precisely identified the portal vein anatomy, total number of accessory inferior right hepatic veins, and the total number of 4 mm thick tributaries from segment V and VIII draining into middle hepatic vein Conclusion: We propose that magnetic resonance venography using FIESTA sequence can be used instead of CT venography to determine hepatic and portal vein anatomy of liver donors.

Prospective comparative analysis for application and selection of FIESTA sequence and SSFSE sequence in MRI for prenatal diagnosis of placenta previa accreta

Placenta previa accreta patients were examined using fast-imaging employing steady-state acquisition (FIESTA) and single-shot fast spin echo (SSFSE) sequence. The diagnostic value of the two sequences was compared. FIESTA was better than the SSFSE sequence in displaying outline-boundary (excellent: 82 vs. 26), signal-to-noise ratio (excellent: 75 vs. 54) for placenta and uterus. The direct signs detection rate in FIESTA was higher than SSFSE (implantable: P = .028, adhesive: P = .131, penetrating type: P = .326). The indirect signs detection rate in FIESTA was lower than SSFSE (low-signal density: P = .029, uneven-signal density: P = .328, thicker and more vascular shadow: P = 398). FIESTA combining SSFSE demonstrated higher detecting rates (100% for sensitivity, specificity, and accuracy) for all types than single sequence scanning (FIESTA/SSFSE). In conclusion, FIESTA clearly showed the situation of the placenta and uterus in placenta previa accreta patients, with excellent image quality. A combination of FIESTA and SSFSE can improve the diagnostic value of placenta previa accreta. Important statement What is already known on this subject? Placenta previa is the most common cause of vaginal bleeding in the third trimester of pregnancy. What do the results of this study add? FIESTA was better than the SSFSE sequence in displaying images and demonstrated higher detection rates for direct signs and lower detection rate comparing the SSFSE sequence. FIESTA combining SSFSE sequence demonstrated higher detecting rates for implantable, adhesive and penetrating types than single sequence scanning. What are the implications of these findings for clinical practice and/or further research? FIESTA sequence clearly showed the situation of placenta and uterus in placenta previa accreta patients, with excellent image quality. Combination of FIESTA and SSFSE sequences can effectively improve the diagnostic value of placenta previa accreta.

Correlation of cochlear nerve cross-sectional area and auditory performance after cochlear implantation in prelingual children with bilateral profound hearing loss

ObjectiveTo assess whether cochlear nerve (CN) cross-sectional area as measured with parasagittal magnetic resonance imaging (MRI) in prelingual pediatric deaf patients correlates with auditory performance after cochlear implantation. Study designProspective Cohort study. MethodsThirty-two prelingual children with bilateral profound sensorineural hearing loss (SNHL) who received unilateral cochlear implant were included in this study. Diameters of CN at Internal auditory canal (IAC) fundus and mid-point of IAC were retrospectively measured on parasagittal images of FIESTA (Fast Imaging Employing Steady-state Acquisition) sequence MRI by two independent observers. Cross-sectional areas [π (Height/2) (Width/2)] were then correlated with post-operative CAPS (Categories of Auditory Performance) and IT-MAIS (Infant-Toddler Meaningful Auditory Integration Scale) scores regularly assessed at 3 monthly intervals post device activation. ResultsThe cochlear nerve was identified in all the 32 patients. Mean cross-sectional areas (CSA) of cochlear nerve were 0.71 ± 0.16 mm2 at IAC fundus and 0.73 ± 0.18 mm2 at mid-point of IAC. The correlation value between CSA at mid-point of IAC and CAPS score at 6 months was 0.271 (p-value- 0.140) and correlation value between CSA at mid-point of IAC and IT-MAIS score at 6 months was 0.282 (p-value- 0.124) which were statistically not significant. ConclusionThere was no significant correlation between the cross-sectional areas of the cochlear nerve on MRI and postoperative auditory scores as measured by CAPS and IT-MAIS scores at six months from the device activation. Hence, we conclude that above an adequate diameter, which can affect the minimum required neurons, the changes in the diameter do not have significant bearing on auditory outcomes after cochlear implantation.

Dynamic Fast Imaging Employing Steady State Acquisition Magnetic Resonance Imaging of the Vocal Tract in One Overtone Male Singer: Our Preliminary Experience

To demonstrate physiological changing of vocal tract's structures during overtone singing with commercial magnetic resonance imaging (MRI) Fast Imaging Employing Steady State Acquisition (FIESTA) dynamic sequence. A 1.5 T MRI with a 16 channel head-and-neck coil and a FIESTA sequence were used. A temporal resolution of 0.155 sec (7 image/s). A single professional singer was studied. The MR acquisition is made while the singer performed a predetermined singing sequence. Three different overtone singing techniques were examined (L-technique, J-technique, and NG technique) and one effect (Ezengileer) applied to L-technique. For each overtone technique we evaluated MRI movement of lips, tongue, velopharyngeal closure, and relationship among tongue and pharyngeal posterior wall/soft palate. To cancel the noise over-imposed, the dynamic MRI was subsequently dubbed in studio with the audio of the preset overtone sing. Dubbed MR images were analyzed with an Overtone Analyzer Software and different sound frequencies were identified and pointed out as colored lines. This study shows that different overtone techniques are related to a specific conformation of tongue, lips, soft and hard palate and motion's relation changing between them. Only a correct conformation of vocal tract's structure allows resonance and so to hear desired fundamental and harmonic pitch in overtone singing. The preliminary data of our study demonstrates that FIESTA dynamic MRI sequence can be used to depict changing of position of vocal tract's structure in overtone singing techniques with a good temporal and anatomic resolution.

Diagnosis of demyelinating brain lesion simulating brain tumors on fast imaging employing steady-state acquisition magnetic resonance imaging.

Background:A single inflammatory demyelinating brain lesion sometimes mimics a brain tumor on conventional magnetic resonance imaging (MRI), and thus poses a considerable diagnostic challenge. We assessed the usefulness of a new MRI technique, fast imaging employing steady-state acquisition (FIESTA), for the diagnosis of inflammatory demyelinating disease (IDD).Methods:Three patients (2 males, 1 female) with a histopathologically proven inflammatory demyelinating brain lesion which mimicked a brain tumor on MRI were evaluated with a post-contrast three-dimensional FIESTA sequence before biopsy and treatment. Those images were compared with the images of intra-axial brain tumors (n = 147).Results:Preoperative FIESTA showed an iso- or slightly hyperintense distinct intralesional structure that appeared reticulate or broad-line in patients with IDD. These structures traversed a hyperintense demyelinating lesion in the deep grey matter (DGM) and were connected to the surrounding extralesional area, which appeared to be dense fibers between DGM. Such distinct intralesional structures were not observed in most brain tumors.Conclusion:Reticulate or broad-line-like intralesional structures on FIESTA may, therefore, be suggestive of IDD rather than indicate a brain tumor.

Imaging Modality of Choice for Pre-Operative Cochlear Imaging: HRCT vs. MRI Temporal Bone.

Congenital inner ear malformations occur as a result of the arrest or aberrance of inner ear development due to the heredity, gene mutation or other factors. Ever since the availability of cochlear implants, pre-operative evaluation by imaging of temporal bone has gained much attention. Precise selection of the candidate for cochlear implant dependent on preoperative radiological investigations. Only CT (Computed Tomography) and MRI (Magnetic Resonance Imaging) can provide a better picture of anatomy and pathology. To compare pre-operative imaging findings of both MRI and High Resolution Computed Tomography (HRCT) temporal bone and to find the best modality of choice in patients with bilateral profound Sensorineural Hearing Loss (SNHL). This was a prospective, longitudinal, observational study conducted between June 2010 to November 2012. A total of 144 temporal bones were evaluated in 72 children with bilateral profound SNHL with congenital inner ear malformations. Each temporal bone was considered as a single case (144 cases). All the patients underwent HRCT and high field MRI study. MRI study included T2 W axial 3D FIESTA (Fast Imaging Employing Steady-state Acquisition) sequence. Anatomic abnormalities in each temporal bone were described and noted. For complete and better evaluation of Vestibulo-Cochlear Nerve (VCN) additional 3D oblique parasagittal view was taken perpendicular to the internal auditory canal with a small Field Of View (FOV). HRCT and MRI allowed accurate detection of inner ear malformations in children with bilateral SNHL. Majority of the patients presented with multiple structural abnormalities of inner ear. The common pathologies detected in the study were semicircular canal abnormality (89/144) followed by cochlear abnormalities (39/144). Most common cochlear abnormality was Mondini's deformity (14/144). MRI demonstrated absent of vestibulo-cochlear nerve in 15 cases. Few abnormalities of inner ear are better illustrated on CT, while others are better showed on MRI. Hence, neither HRCT nor MRI of the brain and temporal bones appears to be adequate imaging modality rather they are complementary to each other for pre-operative imaging of cochlear implantation.

Dynamic MR imaging of temporomandibular joint: an initial assessment with fast imaging employing steady-state acquisition sequence

PurposeThe study was aimed to determine and optimize the parameters for the MR fast imaging employing steady-state acquisition (FIESTA) sequence, which was to obtain an acceptable image to evaluate the value of the movement of the temporomandibular joint (TMJ). MethodsIn this investigation, 20 volunteers were examined to determine and optimize the parameters of the FIESTA sequence. Then, 160 TMJs from 80 patients with temporomandibular joint disorders (TMD) of clinical suspicion were consecutively performed by both static MRI and dynamic FIESTA MRI on the oblique sagittal position. The FIESTA MR images of TMJs were obtained from a slow, consecutive, free and open–closed movement. Based on the cycles of TMJ movements during the process of FIESTA MRI (90seconds), we classified all TMJs into 2 groups: cycles of open–closed mouths less than or equal to 3 (group 1) and more than 3 (group 2). Each image was marked level 1–3 by its quality. Meanwhile, the location of articular disc, mandibular condyle, motive artifact, “jumping sign” and the joint effusion in each TMJ were assessed respectively. ResultsBy dynamic FIESTA MRI among 160 TMJs, 92 TMJs (57.50%) were in group 1, and 68 TMJs were (42.50%) in group 2. There were statistically significant differences between group 1 and group 2(p<0.05). It was shown that the number of “level 3” in group 1 was greater than group 2, and the number of “level 1” in group 1 was less than group 2. The phenomenon of motion artifact and “jumping sign” were much significantly higher in group 2 than those in group 1 (p<0.01). Furthermore, in all of the “jumping sign” cases, the phenomenon of “jumping sign” was significantly higher in group ADDwR than in group ADDw/oR (p<0.01). There was a statistically significant correlation between disc-condyle complex in “jumping sign” phenomenon and group ADDwR (r=0.621, p<0.05). The data with the false matching rate of 31.52% showed that the maximum motion range on the dynamic imaging was greater than the static imaging. Among 160 TMJs, joint effusions of 37 TMJs (23.13%) were identified by dynamic FIESTA-MRI. Among 79 TMJs with ADDw/oR(anterior disc displacement without reduction), 42 sides were operated with Maxillofacial arthroscopy surgery. The surgical result was in agreement with the MR result. ConclusionMost TMJs images with a slow free open–close movement (cycles≦3) could be successfully obtained by the dynamic FIESTA MRI. The FIESTA MRI might be considered as an additional method to evaluate the movement of the articular disk and the mandibular condyle.

CT and MRI findings of temporal bone anomaly in patients with tinnitus

Objective To study high resolution CT (HRCT) and MRI findings of temporal bone anomaly in patients with tinnitus and identify the optimal examination method in the detection of the anomaly. Methods The HRCT and MRI data were analyzed retrospectively in 1015 patients including 145 patients with pulsatile tinnitus (PT) and 870 patients with nonpulsatile tinnitus (NPT). The positive rates of HRCT and MRI in the identification of temporal bone anomaly were analyzed and the efficiency of various examination methods was compared in revealing the anomaly. Data were tested by Chi-square test analysis. Results Among 1015 patients, anomaly was seen in 767 cases (75.57%). High jugular bulb was found in 414 patients, accounting for 40. 79%. Sigmoid sinus anomaly was detected in 387 patients (38. 13%), while otitis media was found in 148 cases (14. 58%), and low middle cranial fossa in 70 cases (6. 90%). The positive rate of HRCT in the detection of high jugular bulb was 54. 89% (365/665), which was significantly higher than those of other methods (P ＜ 0. 05). The positive rate of enhanced HRCT in showing sigmoid sinus anomaly was 73.68% (56/76), which was significantly higher than those of other methods(P ＜0. 05). Sigmoid sinus anomaly was the most frequent finding in patients with PT, accounting for 66. 21% (96/145). The incidence of sigmoid sinus anomaly was higher in PT than in NPT (291/870,33.45% ;χ2 =56. 537 ,P ＜0. 01). The fast imaging employing steady-state acquisition (FIESTA) sequence was the best examination method in displaying the vessel within the internal auditory canal (42/42,100%).Conclusions High jugular bulb and sigmoid sinus anomaly were the most frequent abnormal findings of temporal bone in patients with tinnitus. Enhanced HRCT was the choice of modality in patients with PT.Plain HRCT was recommended for NPT. FIESTA sequence was the best in the evaluation of the vessel within the internal auditory canal. Key words: Tinnitus; Temporal bone; Tomography, X-ray computed; Magnetic resonance imaging

Aqueductal web causing obstructive hydrocephalus demonstrated on sagittal FIESTA sequence

A 4-month-old boy presented with a rapidly increasing head circumference, a bulging anterior fontanelle and dilated scalp veins. Sagittal FIESTA sequence (Fig. 1) demonstrated a marked dilatation of the lateral and third ventricles with a normal fourth ventricle. A small web was noted within the aqueduct (arrow) that was obstructing the aqueduct and resulting in hydrocephalus. An aqueductal web is a congenital translucent membrane composed of fibrillary neuroglia with clumps of ependymal cells [1]. Recognition of this entity is crucial since it is curable by surgical resection, which avoids the morbidity and risks associated with shunting. The FIESTA (fast imaging employing steady state acquisition) is an ultrafast pulse sequence that provides high-resolution images with outstanding image contrast between the cerebrospinal fluid and brain parenchyma and high signal-to-noise ratio, thereby improving conspicuity of small intraventricular lesions like aqueductal webs. A 3D-CISS (constructive interference in steady state) sequence is a similar sequence on scanners from other manufacturers [2].

Evaluation of the Optic Nerve Complex in the Orbit Using Coronal Fast Magnetic Resonance Imaging

Recently available coronal fast magnetic resonance imaging (MRI) has very high spatial resolution with good contrast between the optic nerves and cerebrospinal fluid (CSF). The aim of this study was to evaluate the diagnostic value of coronal fast imaging in optic nerve diseases. Thirty-five patients with various Neuro-ophthalmic conditions including 9 with optic neuritis, 6 with optic atrophy, 5 with glaucoma, 4 with segmental optic nerve hypoplasia and 11 with other optic neuropathies including orbital apex syndrome were evaluated with the three-dimensional fast imaging employing steady-state acquisition (FIESTA) sequence in addition to standard MRI protocols. The optic nerve complexes were evaluated on coronal images of the orbits. Detailed demonstration of the optic nerve complex—the optic nerve, the perineural CSF space and dural sheath—could be readily obtained with FIESTA sequence. The acute phase of both optic neuritis and perineuritis showed enlargement of the perineural CSF space; the optic nerve was swollen in optic neuritis but not in perineuritis. Cases of optic atrophy and glaucoma showed perineural CSF space enlargement with normal optic sheath circumference and a thinner optic nerve, while optic nerve hypoplasia showed a smaller dural sheath circumference without perineural CSF space enlargement. In the cases of orbital apex syndrome optic nerve compression by the extraocular muscles was clearly shown. Coronal FIESTA imaging of the orbit is capable of delineating detailed structural changes in the optic nerve complex and is of diagnostic value for the differentiation of optic nerve diseases.

Utility of the FIESTA Pulse Sequence in Body Oncologic Imaging: Review

The FIESTA (fast imaging employing steady-state acquisition) ultrafast pulse sequence provides high-resolution images with outstanding image contrast and high signal-to-noise ratio relative to the single-shot fast spin-echo (SSFSE) sequence. The purpose of this article is to illustrate the utility of the FIESTA sequence in oncologic imaging. Although the FIESTA technique cannot replace standard imaging techniques, it can be used as an excellent adjunct to conventional T1-and T2-weighted sequences for abdominal imaging and for screening the entire abdomen and pelvis at the beginning of the examination. In addition, the motion-insensitive FIESTA sequence is useful in surgical planning, particularly in patients with retroperitoneal tumors and pancreatic cancer because it offers excellent visualization of the vascular anatomy.

Isolated Sixth Cranial Nerve Aplasia Visualized With Fast Imaging Employing Steady-State Acquisition (FIESTA) MRI

An otherwise healthy 12-month-old girl presented for evaluation of reduced abduction of the left eye detected at 6 months of age. The remainder of the examination was unremarkable. A special MRI sequence-fast imaging employing steady-state acquisition (FIESTA)-visualized the right but not the left sixth nerve cisternal segment. This is the first reported use of the MRI FIESTA sequence to diagnose aplasia of the sixth cranial nerve.

Characterization of breast lesions using the 3D FIESTA sequence and contrast‐enhanced magnetic resonance imaging

To determine whether combining 3D fast imaging employing steady-state acquisition (FIESTA) and T1-weighted contrast-enhanced (CE) sequences could help characterize lesions in 32 women with benign, in situ, or invasive breast lesions. Since FIESTA provides both T1 and T2 information on the same three-dimensional (3D) matrix as high-resolution T1-weighted dynamic data, we aimed to verify whether invasive lesions could be separated from in situ and/or benign lesions using quantitative FIESTA measures of tissue intensity and homogeneity. With the use of CE-MRI data, regions of interest (ROIs) were manually delineated in enhancing lesions and on surrounding normal tissue. These ROIs were then applied to 3D FIESTA data. Quantitative measures between lesion and normal tissue were compared among the lesion groups. On FIESTA most invasive cancer lesions were hypointense compared to surrounding normal tissue (mean lesion intensity was 89% of normal tissue intensity), whereas most ductal and benign lesions appeared hyperintense compared to surrounding normal tissue (lesions at 100.9% and 121.9% of normal tissue intensity, respectively). Measures obtained from resampled T2-weighted data showed no significant differences between the invasive and benign lesion groups. We detected significant differences between invasive and noninvasive lesions by quantifying intensity differences between the lesions and surrounding normal tissue on FIESTA.

Comparison of FIESTA and gadolinium‐enhanced T1‐weighted sequences in magnetic resonance of acoustic schwannoma

AbstractAcoustic schwannomas (AS) are a treatable cause of sensorineural hearing loss (SNHL). Currently, the gold standard magnetic resonance (MR) examination for exclusion of acoustic schwannoma is gadolinium‐enhanced T1‐weighted images of the cerebropontine angles (CPA). The FIESTA (fast imaging employing steady‐state acquisition) sequence is a true‐FISP (free induction steady‐state precession) sequence that provides high‐resolution fluid‐bright images of the CPAs and basal cisterns. The T1‐weighted sequence adds cost and time to the examination, and possibility of contrast medium reaction exists. This study of 50 patients compared the gadolinium‐enhanced T1‐weighted images and FIESTA images. The hypothesis was that the FIESTA sequence could repIACe the gadolinium‐enhanced T1‐weighted images for the diagnosis of AS. The results showed that in 98% of cases, this was possible. The conclusion was that when the FIESTA sequence does not demonstrate AS, this sequence may be employed in isolation. However, gadolinium‐enhanced images should be employed when pathology is seen and to follow‐up post‐surgical patients.

Assessment of Crohn’s disease in the small bowel: prospective comparison of magnetic resonance enteroclysis with conventional enteroclysis

Our objective was to assess the diagnostic value of magnetic resonance enteroclysis (MRE) compared with conventional enteroclysis (CE) in patients with Crohn's disease. A secondary objective was to evaluate the diagnostic accuracy of each different MR sequence. Sixty-six consecutive patients with known Crohn's disease underwent MRE and CE. Fast imaging employing steady-state acquisition (FIESTA), single-shot fast spin-echo (ssFSE), and contrast-enhanced T1-weighted sequences were assessed by two radiologists who reached a consensus about the following findings: visualization of wall ulcers, pseudopolyps, fistulae, mural stenosis, and mesenteric abnormalities. Standard descriptive statistics and the McNemar test were used. The sensitivity, specificity and accuracy of MRE were 90-87% and 83% for the depiction of parietal ulcers, 84%-88% and 86% for pseudopolyps, 100-94% and 96% for mural stenosis, 93-100% and 94% for fistulae. The number of detected extraluminal findings was significantly higher with MRE (P < 0.01). The accuracy of FIESTA sequence was statistically higher in the depiction of wall ulcers and fistulae than that of three-dimensional fast spoiled gradient echo (3D-FSPGR) (P < 0.01) and ssFSE (P < 0.05) sequences. Contrast-enhanced 3D-FSPGR was superior for mural stenosis visualization compared to ssFSE (P < 0.05) and FIESTA (P < 0.05). MRE correlates accurately with CE in the detection of superficial and transmural abnormalities and has the advantage of assessing the mesenteric manifestations.

Cranial nerve assessment in posterior fossa tumors with fast imaging employing steady-state acquisition (FIESTA)

Steady-state free precession is widely used for ultra-fast cardiac or abdominal imaging. The purpose of this work was to assess fast imaging employing steady-state acquisition (FIESTA) and to evaluate its efficacy for depiction of the cranial nerve affected by the tumor. Twenty-three consecutive patients with posterior fossa tumors underwent FIESTA sequence after contrast agent administration, and then displacement of the cranial nerve was evaluated. The 23 patients with posterior fossa tumor consisted of 12 schwannomas, eight meningiomas, and three cases of epidermoid. Except in the cases of epidermoid, intensity of all tumors increased on FIESTA imaging of the contrast enhancement. In the schwannoma cases, visualization of the nerve became poorer as the tumor increased in size. In cases of encapsulated meningioma, all the cranial nerves of the posterior fossa were depicted regardless of location. The ability to depict the nerves was also significantly higher in meningioma patients than in schwannoma patients (P<0.05). In cases of epidermoid, extension of the tumors was depicted clearly. Although the FIESTA sequence offers similar contrast to other heavily T2-weighted sequences, it facilitated a superior assessment of the effect of tumors on cranial nerve anatomy. FIESTA sequence was useful for preoperative simulations of posterior fossa tumors.

Efficiency of breath-hold three-dimensional fast imaging employing steady state acquisition sequence for coronary stenoses detection

目的 以普通冠状动脉导管造影为参照,评价屏气三维快速平衡稳态进动(FIESTA)序列对冠状动脉狭窄的显示效能.方法连续33例患者在冠状动脉导管造影检查的3周内接受冠状动脉MR血管成像(CMRA)检查,将冠状动脉狭窄划分成0%、0%～25%、25%～50%、50%～75%, 75%～100%共5个级别,对两者判断的结果逐段进行比较.结果 CMRA对区分>50%和 <50%狭窄的准确度、敏感度和特异度分别为84.3%、84.8%和84.1%,阴性预测值为92.3%;对区分50%～75%与75%～100%狭窄的准确度、敏感度和特异度均为61.5%.结论屏气三维FIESTA冠状动脉成像序列对具有血流动力学意义狭窄的排除具有一定的实用价值,但是更细致的分级受限。