Constructive Interference In Steady State Sequence Research Articles

Reduced Cochlear MRI Signal and Hearing Outcomes in Conservatively Managed Vestibular Schwannoma Patients.

This study aimed to determine if hypointense cochlear magnetic resonance imaging (MRI) constructive interference in steady-state (CISS) signal correlates with hearing outcomes in conservatively managed vestibular schwannoma (VS) patients. Retrospective review of 657 cases from 1992 to 2020. Tertiary academic referral center. A retrospective review was performed to identify conservatively managed VS patients with appropriate baseline MRI, audiology, and at least 12-month audiological follow-up. Patients were excluded if they progressed to surgery or radiotherapy in less than 12 months, bilateral tumors, or surgery on the contralateral ear. Conservatively managed patients with CISS imaging studies and audiology testing. Primary outcome measure change in pure-tone average (PTA) and word recognition score (WRS). Secondary outcome measures tumor size, presence of lateral fluid cap, or cystic changes. A total of 92 individuals (47% male, 58 ± 11.6 yr) met the inclusion criteria, with 36 (39%) of patients demonstrating abnormal cochlear CISS signal. At baseline, abnormal cochlear CISS signal was associated with higher intracanalicular (IC) length (7.9 versus 6.6 mm, p = 0.0177) and lower WRS (55.7 versus 78.8 dBHL, p = 0.0054). During follow-up, individuals with abnormal cochlear CISS signal had significantly higher PTA (62.4 versus 46.4 dBHL, p = 0.0010). After adjusting for baseline covariates, abnormal cochlear CISS signal was consistently associated with a greater increase in PTA of 8.3 dBHL (95% confidence interval, 2.9-13.7; p = 0.0032) from baseline when compared with the normal group. Abnormal cochlear signal on MRI CISS sequences is associated with poorer hearing outcomes in conservatively managed VS patients.

Patterns of Signal Intensity in CISS MRI of the Inner Ear and Eye.

Constructive interference in steady state (CISS) is a gradient echo magnetic resonance imaging (MRI) pulse sequence that provides excellent contrast between cerebrospinal fluid and adjacent structures but is prone to banding artifacts due to magnetic field inhomogeneities. We aimed to characterize artifacts in the inner ear and eye. In 30 patients (60 ears/eyes) undergoing CISS sequence MRI, nine low-signal intensity regions were identified in the inner ear and compared to temporal bone histopathology. The number and angle of bands across the eye were examined. In the cochlea, all ears had regions of low signal corresponding to anatomy (modiolus (all), spiral lamina (n = 59, 98.3%), and interscalar septa (n = 50, 83.3%)). In the labyrinth, the lateral semicircular canal crista (n = 42, 70%) and utricular macula (n = 47, 78.3%) were seen. Areas of low signal in the vestibule seen in all ears may represent the walls of the membranous utricle. Zero to three banding artifacts were seen in both eyes (right: 96.7%, mean 1.5; left: 93.3%, mean 1.3). Low signal regions in the inner ear on CISS sequences are common and have consistent patterns; most in the inner ear represent anatomy, appearing blurred due to partial volume averaging. Banding artifacts in the eye are more variable.

Capability of constructive interference in steady state sequence versus postcontrast T1-weighted imaging in cerebellopontine angle and internal auditory canal masses

Background: The tumor size is one of the main factors in the treatment of cerebellopontine angle (CPA) tumors, and magnetic resonance imaging (MRI) with gadolinium-based contrast agent (GBCA) provides the best evaluation. However, administration of the gadolinium is time consuming and increasing in cost. There is a risk of nephrogenic systemic fibrosis in patients with renal failure and liver or renal transplantation. Objective: The purpose of this study was to assess the capability of constructive interference in steady state (CISS) sequence in measuring the tumor size of the CPA and internal auditory canal (IAC) masses compared to postcontrast T1-weighted images (T1-WI). Materials and Methods: The 118 MR studies with both CISS sequence and postcontrast T1-WI of 45 patients with CPA and IAC masses were retrospectively reviewed. Results: There was no significant difference between CISS and postcontrast T1-WI in measuring size in transverse diameter of the masses (p = 0.051-0.06). The longitudinal diameter measurement revealed a significant difference (p < 0.001) and the measured size on postcontrast T1-WI was slightly larger than the CISS image. The difference in median measurement between two sequences was less than 0.9 mm. and Bland-Altman plots revealed that differences between the two sequences in longitudinal and transverse diameters of the masses were within the limits of agreement. Interobserver agreement showed excellent correlation (r = 0.994-0.999, p < 0.001 by Pearson's product-moment correlation). Conclusions: The CISS sequence may be sufficient for assessing the size of CPA and IAC masses, which can be used interchangeably with postcontrast T1-weighted image as a contrast-free option, especially in follow-up studies and vulnerable settings of gadolinium administration.

Delineation of intermammillary relationships using magnetic resonance imaging.

No study has investigated intermammillary relationships using neuroimaging modalities. This study aimed to explore them using magnetic resonance imaging (MRI). We enrolled 72 patients who underwent conventional MRI examinations, followed by constructive interference steady-state sequence in the coronal plane. The intermammillary distances (IMDs) were measured at the uppermost level of the intermammillary gap (IMDupp) and the lowest level (IMDlow) of the mammillary bodies (MBs). MBs with varying morphologies were consistently delineated. The appearance of both MBs could be classified into four patterns based on the size and relative levels, with the symmetrical type being the most common. Intermammillary relationships exhibited five patterns. In 69%, the IMDupp was discernible and measured 0.7 ± 0.4mm, while it was not discernible in 31% due to the presence of intermammillary connection and adhesion. The age distribution did not differ between populations with and without discernible IMDupp. The IMDlow was measured 4.4 ± 0.9mm. Although the IMDlow was not significantly different between both sexes; it was longer in subjects in their 70s. Intermammillary relationships show variable morphologies with gaps formed between both MBs. The IMDlow may become more evident in association with age-related increase in the width of the third ventricle and atrophy of the MBs.

Symptoms: Sudden Hearing Loss and Aural Fullness

Symptoms: Sudden Hearing Loss and Aural Fullness

57-Year-Old Man With Headache, Vomiting, and Gait Instability

57-Year-Old Man With Headache, Vomiting, and Gait Instability

Comparison of 3D constructive interference in steady state (CISS) and T2 sampling perfection with application optimized contrasts using different flip angle evolution MR imaging of the intracranial trigeminal nerve and central skull base neuroforamina.

Due to surgical advancements, the accurate detection of perineural disease spread has become increasingly important in the management and prognostication of head and neck cancers, though MR evaluation has thus far been limited by technical and logistic challenges. The purpose of this study was to specifically evaluate the relative capability of 3D CISS and 3D T2-SPACE imaging to delineate the proximal intracranial divisions of the normal trigeminal nerve, an area important in determining the resectability of intracranial perineural disease. A single center HIPAA-compliant, IRB approved retrospective review of 40 patients with clinical temporal bone/internal auditory canal MR imaging was conducted. 20 patients with 3D CISS images and 20 patients with 3D T2-SPACE images met inclusion criteria. Two radiologists scored the sequences on a 3-point scale based on ability to visualize anatomic structures surrounding the trigeminal nerve in Meckel's cave, intracranial trigeminal divisions, skull base neuroforamina, and proximal extracranial mandibular division. The following anatomic locations scored significantly better in the T2-SPACE sequence compared to the CISS sequence for both raters: intracranial V3 (p < .05), foramen ovale (p < .05), and extracranial V3 (p < .01). The average scores for the anterior Meckel's cave and foramen rotundum were higher for the T2-SPACE sequence, although not significantly. Percent interobserver agreement ranged from 50 to 90% and 65-100% for the different anatomic locations on the CISS and T2-SPACE sequences, respectively. 3D T2-SPACE was found to be superior to 3D CISS in the evaluation of the distal intracranial and extracranial portions of the normal trigeminal nerve.

Reproducibility and postacquisition correction methods for quantitative magnetic resonance imaging of the anterior cruciate ligament (ACL).

Quantitative magnetic resonance imaging has been used to evaluate the structural integrity of knee joint structures. However, variations in acquisition parameters between scanners pose significant challenges. Understanding the effect of small differences in acquisition parameters for quantitative sequences is vital to the validity of cross-institutional studies, and for the harmonization of large, heterogeneous datasets to train machine learning models. The study objective was to assess the reproducibility of T2 * relaxometry and the constructive interference in steady-state sequence (CISS) across scanners, with minimal hardware-necessitated changes to acquisition parameters. It was hypothesized that there would be no significant differences between scanners in anterior cruciate ligament T2 * relaxation times and CISS signal intensities (SI). Secondarily, it was hypothesized that differences could be corrected by rescaling the SI distribution to harmonize between scanners. Seven volunteers were scanned on 3T Prisma and Tim Trio scanners (Siemens). Three correction methods were evaluated for T2 *: inverse echo time scaling, z-scoring, and Nyúl histogram matching. For CISS, scans were normalized to cortical bone, scaled by the background noise ratio, and log-transformed. Before correction, significant mean differences of 6.0 ± 3.2 ms (71.8%;p = 0.02) and 0.49 ± 0.15 units (40.7%; p = 0.02) for T2 * and CISS across scanners were observed, respectively. After rescaling, T2 * differences decreased to 2.6 ± 2.7 ms (23.9%;p = 0.03), 1.3 ± 2.5 ms (10.9%;p = 0.13), and 1.27 ± 3.0 ms (19.6%;p = 0.40) for inverse echo time, z-scoring, and Nyúl, respectively, while CISS decreased to 0.01 ± 0.11 units (4.0%; p = 0.87). These findings suggest that small acquisition parameter differences may lead to large changes in T2 * and SI values that must be reconciled to compare data across magnets.

In vivo detection of the lumbar intraforaminal ligaments by MRI

PurposeIntraforaminal ligaments (IFL) are of great interest to anatomists and clinicians to fully understand the detailed anatomy of the neuroforamina and to diagnose unclear radicular symptoms. Studies published until now have described radiological imaging of the IFLs using magnetic resonance imaging (MRI) on donor bodies. In the present study, we investigated the detectability of lumbar IFLs in vivo in adults using the high spatial resolution of the constructive interference in steady state (CISS) sequence.MethodsA total of 14 patients were studied using a 1.5 T MRI scanner. The lumbar spine was imaged using the parasagittal CISS sequence, and the detectability of the IFLs was assessed for each lumbar level. All image datasets were analyzed by a radiologist, an orthopedic surgeon, and an anatomist. Interrater reliability was expressed as Fleiss’ Kappa. Using a single data set, a three-dimensional (3D) model was created to map the location of the IFLs within the intervertebral foramen (IF) and the immediate surrounding vessels.ResultsOverall, the radiologist was able to detect IFLs in 60% of all imaged IFs, the orthopedic surgeon in 62%, and the anatomist in 66%. Fleiss’ Kappa for the various segments varies from 0.71 for L4/5 up to 0.90 for L3/4.ConclusionLumbar IFLs were successfully detected in vivo in every patient. The detection frequency varied from 42–86% per IF. We demonstrated reproducible imaging of the IFLs on MRI, with good interrater reliability. The present study was a launching point for further clinical studies investigating the potential impact of altered IFLs on radicular pain.

Inductively Coupled Intraoral Flexible Coil for Increased Visibility of Dental Root Canals in Magnetic Resonance Imaging.

Accurate visualization of dental root canals is vital for the correct diagnosis and subsequent treatment. This work assesses the improvement of a dedicated new coil for dental magnetic resonance imaging (MRI) in comparison to conventional ones in terms of signal-to-noise ratio (SNR) and visibility. A newly developed intraoral flexible coil was used to display dental roots with MRI, and it provides improved sensitivity with a loop design and size adjusted to a single tooth anatomy. Ex vivo and in vivo measurements were performed on a 3 T clinical MR system, and results were compared with conventional head and surface coil images. Additional comparison was performed with a modified fast spin echo sequence and a constructive interference in steady-state sequence. Ex vivo, an SNR gain of 6.3 could be achieved with the intraoral flexible coil setup, and higher visibility down to 200 μm was possible, whereas the external loop coil is limited to 400 μm. In vivo measurements in a volunteer resulted in an SNR gain of up to 4.5 with an improved delineation of the root canals, especially for the branch tissue splitting of the mesial root canal into mesial-buccal and mesial-lingual. In summary, we showed the feasibility of implementing a wireless coil approach with readily available dental practice materials for sealing and placement. Highly improved MRI scans can be acquired within clinically feasible scan times, and this might provide additional medical findings to supplement available x-ray images.

The Arcuate Eminence and Superior Semicircular Canal: Magnetic Resonance Imaging Study.

The present study aimed to explore the relationship between the arcuate eminence (AE) and superior semicircular canal (SSC) using the constructive interference steady-state (CISS) sequence. After conventional magnetic resonance imaging, a total of 71 patients underwent the CISS sequence in thin-sliced coronal sections. In all patients, the SSC was delineated on both sides. In contrast, the AE was identified only in 29 of 71 patients (40.8%) on both sides, varying in shape and relative location to the SSC in the mediolateral dimension. The shortest distance between the highest point of the SSC and middle fossa floor was 1.3 ± 1.1 mm on the right side and 1.3 ± 0.9 mm on the left with considerable variability. A dehiscent SSC with a distance less than 0.2 mm was found in 11.3% of 142 sides. On 22 sides (15.5%), the site on the middle fossa floor, reaching the SSC with the shortest distance (reference point) corresponded to the apex of the AE, equally on the right and left. On 36 sides (25.4%), the distance between the reference point and the apex of the AE was measured as 3.0 ± 1.1 mm on the 18 right sides and 3.7 ± 1.6 mm on the 18 left sides. The relationship between AE and SSC is highly variable. Arcuate eminence was not a reliable landmark of the SSC. High-resolution CISS sequence is useful for exploring these structures.

Accuracy and Interrater Reliability of CISS Versus Contrast-Enhanced T1-Weighted VIBE for the Presence of Optic Canal Invasion in Tuberculum Sellae Meningiomas

The magnetic resonance imaging sequence used to assess optic canal invasion by tuberculum sella meningiomas (TSMs) has not been standardized. Both constructive interference in steady state (CISS) and contrast-enhanced T1-weighted volume-interpolated breath-hold examination (VIBE) sequences are frequently used. The aim of the present study was to compare the accuracy and interrater reliability of these sequences in predicting optic canal invasion by TSMs. In the present retrospective study of 27 patients (54 optic canals) who had undergone endoscopic transtuberculum transplanum resection of TSMs, images from preoperative CISS and contrast-enhanced T1-weighted VIBE sequences were assessed by 5 neuroradiologists who were unaware of the operative findings. The readers evaluated the optic canal in 4 quadrants at 2 locations (the posterior tip of the anterior clinoid process and the optic strut). A quadrant was considered positive for tumor invasion if invasion was present at either of these 2 locations. The reference standard was intraoperative observation of gross optic canal invasion. The interrater agreement was good for the presence or absence of tumor involvement in a particular quadrant (CISS, 0.635; VIBE, 0.643; 95% confidence interval for the difference,-0.086 to 0.010). The mean sensitivity and specificity for optic nerve invasion were 0.643 and 0.438 with CISS and 0.643 and 0.454 with VIBE, respectively. No significant differences were seen between the sequences in terms of reader accuracy when the intraoperative findings were used as the reference standard. CISS and VIBE sequences both have good accuracy in predicting for optic canal tumor invasion by TMEs.

Trochlear cistern of the cavernous sinus: an anatomical study using magnetic resonance imaging.

The present study aimed to explore the trochlear cistern (TC) of the cavernous sinus using magnetic resonance imaging (MRI). Following conventional MRI examination, a total of 73 patients underwent the constructive interference steady-state (CISS) sequence in thin-sliced coronal sections. Moreover, three injected cadaver heads were dissected. In the cadaver specimens, the extent of the TC was difficult to identify on any dissected side. On the CISS images, the TC was identified in 98.6% on the right side and 94.5% on the left, while transmitting the trochlear nerve (TN) was identified in 83.6% on the right and 79.5% on the left. Most TNs were delineated as a single trunk, while duplication of the nerve was found in 3% of cases. The TC, commonly located inferior or inferolateral aspect of the oculomotor trigone. The size and extent of TC were highly variable. The TN location in the TC was also variable and was identified throughout the upper, middle, and lower parts of the TC. Moreover, relationships between the TC and Meckel's cave were highly variable. TC shows morphological variability. The coronal CISS sequence is useful for exploring TC and TN in clinical practices.

Utility of CISS imaging in the management of tethered cord syndrome

To compare the utility of constructive interference in steady-state (CISS) sequence over T2-weighted (T2W) sequence in the accurate delineation of the tethering element on magnetic resonance (MR) imaging in patients of tethered cord syndrome (TCS) and correlation with intraoperative findings. MR findings of fifty-six consecutive patients with operative findings of TCS were studied. The intraoperative findings of all patients were studied and compared with the preoperative imaging findings on T2W imaging and CISS images. CISS images provided more information than T2W imaging. The overall sensitivity of CISS in MR evaluation of patients with TCS was higher (99.17%) as compared with the T2W sequence (71.48%) especially in the detection of precise position/extent of tethered cord, assessment of filum terminale thickening, detection of a fibrous spur in cases of split cord malformation, detection of dorsal dermal sinus, and evaluation of its precise extent and ramifications. The area under the ROC curve was higher with CISS (0.99) than with T2W sequence (0.85) which reflects its good predictive value as a screening test. This information was useful to the operating surgeon. CISS sequence for imaging TCS can help enhance the overall surgical outcome of the patients ensuring completeness of the surgery. CISS should be routinely performed in the work-up of patients with tethered cord syndrome.

Symptoms: Dizziness and Sudden Hearing Loss

Symptoms: Dizziness and Sudden Hearing Loss

Interdural high signal on CISS sequence: an alternative CSF pathway?

The falx cerebri, falx cerebelli, and tentorial notch exhibit a peculiar morphology with a two-layered, dural leaf that protrudes into the cranial cavity with a free edge. However, there are few studies exploring this morphology using neuroimaging techniques. The present study aimed to explore these dural structures using magnetic resonance imaging. A total of 65 outpatients were included in this study. Following initial examinations with conventional sequences, the constructive interference in steady-state (CISS) sequences were performed in thin-sliced, coronal sections. In 78% of the subjects, the interdural spaces presenting with high signal were identified in the falx cerebri. These spaces were located adjacent to the uppermost part of the falx, formed by two dural leaves and the superior sagittal sinus, and tapered downward where the leaves united to form the falx cerebri. At the tentorial notch, these spaces were found in 52% of the 65, most predominantly in the medial edge followed by the tentorium cerebelli-tentorial notch junctional region. Forty-one percent of patients had a dural opening into the cerebral cistern. The interdural spaces with high signal were not identified in the tentorium cerebelli in any of the subjects. The falx cerebri and tentorial notch form the interdural spaces that may provide alternative cerebrospinal fluid pathways. The coronal CISS sequence is suitable for delineating such interdural spaces.

Significance of the Cerebellopontine Cistern Cross-Sectional Area and Trigeminal Nerve Anatomy in Trigeminal Neuralgia: An Anatomical Study Using Magnetic Resonance Imaging.

To evaluate the relationship between trigeminal neuralgia (TN) and potential magnetic resonance imaging (MRI)-related measurements in patients with TN. Retrospective analysis of 104 patients with TN was performed. MRI studies of 98 healthy controls were included in the study to compare the parameters with TN patients’ measurements. MRI measurements of cerebellopontine cistern (CPC) cross-sectional area, trigeminal-pontine angle (TPA) width, and trigeminal nerve cisternal segment length and thickness were assessed on both symptomatic and asymptomatic sides using 1.5T MRI with constructive interference in steady-state sequences. The images were interpreted by two radiologists blinded to the affected sides of the patients. There were significant differences between the symptomatic and asymptomatic sides in terms of mean trigeminal nerve length (8.8 ± 2.34 mm vs. 9.39 ± 2.29 mm; respectively, p=0.001) and thickness (20.9 ± 9.6 mm2 vs. 25 ± 9.98 mm2, respectively; p < 0.001). The median cerebellopontine cistern cross-sectional area was considerably lower on the symptomatic side compared with the asymptomatic side [201 mm2 (interquartile range=93) vs. 224.5 mm2 (interquartile range=77), respectively; p < 0.001]. There were no significant differences between the trigeminal-pontine angle width on either side (38.32 ± 10.38 vs. 38.78 ± 10.9, respectively; p=0.679). There were no statistically significant differences between the right and left sides regarding these parameters in the control group. Smaller CPC cross-sectional area, trigeminal nerve length, and trigeminal nerve thickness on MRI were demonstrated to commonly exist on the symptomatic side in patients with TN. We suggest that this narrow space may increase the risk of vascular compression on the nerve.

Comparison of Constructive Interference in Steady-State and T1-Weighted MRI Sequence at Detecting Pituitary Adenomas in Cushing's Disease Patients.

Background T1-weighted magnetic resonance imaging (MRI) remains the standard pituitary imaging sequence. However, up to 50% of pituitary adenomas are missed with standard imaging in Cushing's disease (CD) patients. Utility of other imaging sequences needs be explored. Objective To compare a T2-gradient echo sequence, constructive interference in steady state (CISS), with a contrast-enhanced (CE) T1-weighted sequence, volume-interpolated breath-hold examination (VIBE), in the detection of pituitary adenomas in CD patients. Design Retrospective analysis of CD patients who underwent endoscopic transsphenoidal pituitary adenomectomy at our institution. Patients and Measurement Twelve patients were included in the study. Two neuroradiologists, who were blinded to the patients' clinical and surgical findings, independently reviewed the CE-VIBE and CISS images. Localization of pituitary adenoma from imaging was compared with intraoperative localization. Results The averaged sensitivity of detecting pituitary adenoma in CD patients was not significantly different between CE-VIBE sequence (63%) and CISS sequence (54%). The positive predictive value was 75% (Observer A) and 100% (Observer B) with CE-VIBE sequence, and 64% (Observer A) and 100% (Observer B) with CISS sequence. In two patients, pituitary adenoma was easily localized with CISS sequence but hard to detect with CE-VIBE sequence. In two other patients, the adenoma was much better delineated on CE-VIBE sequence. Conclusion In our series, the addition of CISS sequence to T1-weighted MRI imaging protocols improved the detection of pituitary adenomas in CD patients. CISS sequence may be a useful adjunct to T1-weighted pituitary MRI protocols and an appropriate alternative for patients with gadolinium contraindications.

Visualization of the periventricular Virchow-Robin spaces with ependymal openings.

The morphological relationships between the periventricular Virchow-Robin spaces (VRSs) and cerebral ventricles have been poorly documented. The present study aimed to explore the issue using magnetic resonance imaging. A total of 211 patients were included in this study. T2-weighted and constructive interference in steady state (CISS) sequences were performed in thin-sliced, coronal sections. On T2-weighted sequence, the periventricular VRSs with ependymal openings were identified in 34% of 139 subjects. All the openings were located in the lateral wall of the anterior horn. In CISS sequences, such VRSs were found in 39% of 72 subjects. The mean age was significantly higher in the population with such VRSs compared to those without VRSs (p = 0.0047). Of the 58 periventricular VRSs with ependymal openings identified on T2-weighted images, 16% were located in the upper, 36% in the middle, and 48% in the lower part of the lateral wall. Of the 38 such VRSs identified on CISS images, 32% were located in the upper, 24% in the middle, and 42% in the lower part of the lateral wall, and 3% in the upper part of the medial wall. The ependymal openings of the periventricular VRSs may be centered in the lateral wall of the anterior horn. The coronal CISS sequence can sensitively delineate the VRSs with ependymal openings.

Agreement between transverse T2-weighted and three-dimensional constructive interference in steady state sequences in the evaluation of spinal cord disease in dogs

The constructive interference in steady state (CISS) sequence has been widely used in human neuroimaging. It has been shown to be advantageous in the evaluation of intra-axial and extra-axial cystic...