Accelerated Internal Auditory Canal Screening Magnetic Resonance Imaging Protocol With Compressed Sensing 3-Dimensional T2-Weighted Sequence

Clinical feasibility of CS-VIBE accelerates MRI techniques in diagnosing intracranial metastasis

Our objective was to evaluate and compare the diagnostic performance of post-contrast 3D compressed-sensing volume-interpolated breath-hold examination (CS-VIBE) and 3D T1 magnetization-prepared rapid-acquisition gradient-echo (MPRAGE) in detecting intracranial metastasis. Additionally, we analyzed and compared the image quality between the two. We enrolled 164 cancer patients who underwent contrast-enhanced brain MRI. Two neuroradiologists independently reviewed all the images. The signal-to-noise ratio (SNR), contrast-to noise ratio (CNR) were compared between two sequences. For patients with intracranial metastasis, we measured enhancement degree and CNR_{lesion/parenchyma} of the lesion. The overall image quality, motion artifact, gray-white matter discrimination and enhancing lesion conspicuity were analyzed. Both MPRAGE and CS-VIBE showed similar performance in diagnosing intracranial metastasis. Overall image quality of CS-VIBE was better with less motion artifact; however conventional MPRAGE was superior in enhancing lesion conspicuity. Overall, the SNR and CNR of conventional MPRAGE were higher than those of CS-VIBE. For 30 enhancing intracranial metastatic lesions, MPRAGE showed a lower CNR (p = 0.02) and contrast ratio (p = 0.03). MPRAGE and CS-VIBE were preferred in 11.6 and 13.4% of cases, respectively. In comparison with conventional MPRAGE, CS-VIBE achieved comparable image quality and visualization, with the scan time being half of that of MPRAGE.

Guidelines for magnetic resonance imaging in pediatric head and neck pathologies: a multicentre international consensus paper

The use of standardized imaging protocols is paramount in order to facilitate comparable, reproducible images and, consequently, to optimize patient care. Standardized MR protocols are lacking when studying head and neck pathologies in the pediatric population. We propose an international, multicenter consensus paper focused on providing the best combination of acquisition time/technical requirements and image quality. Distinct protocols for different regions of the head and neck and, in some cases, for specific pathologies or clinical indications are recommended. This white paper is endorsed by several international scientific societies and it is the result of discussion, in consensus, among experts in pediatric head and neck imaging.

Compressed-sensing accelerated magnetic resonance imaging of inner ear

Objective

To compare conventional method and compressed‐sensing (CS) accelerated 3D balanced fast field echo imaging (bFFE) of inner ear.

Methods

Twenty patients with suspected inner ear disease underwent CS accelerated 3D‐bFFE (CS‐bFFE) and conventional 3D‐bFFE (Con‐bFFE) by a 3T MRI. The overall image quality, motion artifacts, and image quality of specific structures of inner ear were assessed on ordinal scales by three radiologists who were blinded to the scan protocols. Kendall W test was used to evaluate interobserver agreement and Wilcoxon test was performed to compare the image quality and motion artifacts between CS‐bFFE and Con‐bFFE.

Results

The acquisition duration of CS‐bFFE (1 min 53 s) was 49% faster than Con‐bFFE. Three radiologists had good inter‐observer agreement of image quality (Kendall W value of 0.829 for CS‐bFFE and 0.815 for Con‐bFFE) and motion artifacts evaluation (Kendall W value of 0861 for CS‐bFFE and 0.707 for Con‐bFFE). The better overall image quality of CS‐bFFE was assessed (4.93 ± 0.23 for CS‐bFFE, 4.53 ± 0.70 for Con‐bFFE, Z = −2.254, p = 0.024). The image quality score of facial and cochlear nerve gained higher in CS‐bFFE (4.93 ± 0.23 for CS‐bFFE, 4.58 ± 0.64 for Con‐bFFE, Z = −2.094, p = 0.036). No significant difference of motion artifacts (p = 0.050) between CS‐bFFE and Con‐bFFE.

Conclusions

The CS‐bFFE improves image quality and reduces acquisition time significantly, and it is a feasible MRI protocol for inner ear imaging.

CS-VIBE accelerates cranial nerve MR imaging for the diagnosis of facial neuritis: comparison of the diagnostic performance of post-contrast MPRAGE and CS-VIBE

OBJECTIVE

We aimed to compare the diagnostic performance of post-contrast 3D compressed sensing volume-interpolated breath-hold examination (CS-VIBE) and 3D T1 magnetization-prepared rapid-acquisition gradient-echo (MPRAGE) in detecting facial neuritis.

MATERIALS AND METHODS

Between February 2019 and September 2019, 60 patients (30 facial palsy patients and 30 controls) who underwent contrast-enhanced cranial nerve MRI with both conventional MPRAGE and CS-VIBE (scan time: 6 min 8 s vs. 2 min 48 s) were included in this retrospective study. All images were independently reviewed by three radiologists for the presence of facial neuritis. In patients with facial palsy, signal-to-noise ratio (SNR) of the pons, enhancement degree and contrast-to-noise ratio (CNR_nerve-CSF) of the facial nerve were measured. The overall image quality, artifacts, and facial nerve discrimination were analyzed. The sensitivity and specificity of both sequences were calculated with the clinical diagnosis as a reference.

RESULTS

CS-VIBE had comparable performance in the detection of facial neuritis to that of MPRAGE (sensitivity and specificity, 97.8% and 99.4% vs. 100.0% and 99.4% in pooled analysis; 97.8% and 98.9% vs. 100.0% and 98.9% in patents with facial palsy, p value > 0.05 for all). CS-VIBE showed significantly lower SNR (p value < 0.001 for all), but significantly higher CNR_nerve-CSF (p value < 0.05 for all) than MPRAGE. CS-VIBE also performed better in the overall image quality, artifacts, and facial nerve discrimination than MPRAGE (p value < 0.001 for all).

CONCLUSION

CS-VIBE achieved comparable diagnostic performance for facial neuritis compared to the conventional MPRAGE, with the scan time being half of that of MPRAGE.

KEY POINTS

• Post-contrast 3D CS-VIBE MRI is a reliable method for the diagnosis of facial neuritis. • CS-VIBE reduces the scan time of cranial nerve MRI by more than half compared to conventional T1-weighted image. • CS-VIBE had better performance in contrast-to-noise ratio and favorable image quality compared with conventional T1-weighted image.

Dedicated 3D-T2-STIR-ZOOMit Imaging Improves Demyelinating Lesion Detection in the Anterior Visual Pathways of Patients with Multiple Sclerosis

BACKGROUND AND PURPOSE

Demyelinating lesions in the anterior visual pathways represent an underestimated marker of disease dissemination in patients with MS. We prospectively investigated whether a dedicated high-resolution MR imaging technique, the 3D-T2-STIR-ZOOMit, improves demyelinating lesion detection compared with the current clinical standard sequence, the 2D-T2-STIR.

MATERIALS AND METHODS

3T MR imaging of the anterior visual pathways (optic nerves, chiasm, and tracts) was performed using 3D-T2-STIR-ZOOMit and 2D-T2-STIR, in patients with MS and healthy controls. Two experienced neuroradiologists assessed, independently, demyelinating lesions using both sequences separately. 3D-T2-STIR-ZOOMit scan-rescan reproducibility was tested in 12 patients. The Cohen κ was used for interrater agreement, and the intraclass correlation coefficient for reproducibility. Between-sequence detection differences and the effects of location and previous acute optic neuritis were assessed using a binomial mixed-effects model.

RESULTS

Forty-eight patients with MS with (n = 19) or without (n = 29) past optic neuritis and 19 healthy controls were evaluated. Readers' agreement was strong (3D-T2-STIR-ZOOMit: 0.85; 2D-T2-STIR: 0.90). The 3D-T2-STIR-ZOOMit scan-rescan intraclass correlation coefficient was 0.97 (95% CI, 0.96-0.98; P < .001), indicating excellent reproducibility. Overall, 3D-T2-STIR-ZOOMit detected more than twice the demyelinating lesions (n = 89) than 2D-T2-STIR (n = 43) (OR = 2.7; 95% CI, 1.7-4.1; P < .001). In the intracranial anterior visual pathway segments, 33 of the 36 demyelinating lesions (91.7%) detected by 3D-T2-STIR-ZOOMit were not disclosed by 2D-T2-STIR. 3D-T2-STIR-ZOOMit increased detection of demyelinating lesion probability by 1.8-fold in patients with past optic neuritis (OR = 1.8; 95% CI, 1.2-3.1; P = .01) and 5.9-fold in patients without past optic neuritis (OR = 5.9; 95% CI, 2.5-13.8; P < .001). No false-positive demyelinating lesions were detected in healthy controls.

CONCLUSIONS

Dedicated 3D-T2-STIR-ZOOMit images improved substantially the detection of MS disease dissemination in the anterior visual pathways, particularly in the intracranial segments and in patients without past optic neuritis.

Compressed sensing and parallel imaging accelerated T2 FSE sequence for head and neck MR imaging: Comparison of its utility in routine clinical practice

PURPOSE

To directly compare the capability of compressed sensing (CS) and parallel imaging (PI) accelerated T2 FSE (Fast Spin Echo) sequence with PI for head and neck MR imaging.

METHODS

Thirty consecutive patients with various head and neck diseases (15 men and 15 women, mean age 53 ± 22 years) underwent MR imaging by PI with CS and by PI. Reduction factors were as follows: PI with CS, 3 and PI, 1.5. Examination times for PI with CS and PI were all recorded. For quantitative image quality assessment, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. For qualitative assessment, two investigators assessed overall image quality, artifacts and diagnostic confidence level using a 5-point scoring system, and final scores were determined by consensus of two readers. Mean examination time and all indexes were compared by means of paired t-test and Wilcoxon signed-rank test. Inter-observer agreement for each qualitative index was assessed in terms of kappa statistics.

RESULTS

Mean examination time for PI with CS (83.5 ± 11.0 s) was significantly shorter than that for PI (173.0 ± 54.4 s, p < 0.0001). SNR and CNR of PI with CS were significantly better than those with PI (mean SNR; 11.2 ± 3.6 vs 8.9 ± 2.6, median of CNR; 7.4 vs. 6.1, p < 0.0001). All inter-observer agreements were assessed as significant and substantial (0.62 < κ < 0.81).

CONCLUSION

PI with CS accelerated T2 weighted sequence performs equally well or even slightly better than its PI accelerated, conventional counterpart at reduced scan times in the context of head and neck MR imaging.

Accelerating Brain 3D T1-Weighted Turbo Field Echo MRI Using Compressed Sensing-Sensitivity Encoding (CS-SENSE)

PURPOSE

To evaluate the clinical application of the accelerated 3D T1-weighted turbo field echo (T1W-TFE) using the compressed sensing-sensitivity encoding (CS-SENSE) and identify the appropriate acceleration factor.

METHODS

33 healthy controls (HC), 10 multiple sclerosis (MS) and 10 Alzheimer's disease (AD) patients were prospectively recruited. A conventional 3D T1W-TFE sequence and accelerated sequences with CS-SENSE factors of 3, 4.5, 6 and with SENSE factors of 3, 4.5 were acquired for all participants on a 3.0T MR system. The visual evaluation was independently assessed by two experienced radiologists. Quantitative image quality metrics and intraclass correlation coefficients (ICCs) between the conventional and the accelerated sequences were performed at the voxel level. Group comparisons were performed between HC and AD or MS patients.

RESULTS

There were no significant differences in the visual image quality metrics between conventional sequence and CS-SENSE factor of 3. The sequences with CS-SENSE factor of 6 and SENSE factors of 3, 4.5 showed significantly decreased overall image quality. The ICC values based on the voxel level of each accelerated scan and conventional scan were high (>0.9, 85.2%). For different accelerated sequences, AD and MS patients showed consistent results with the conventional sequence in gray matter atrophy when compared to HC.

CONCLUSIONS

CS-SENSE factor of 3 is the appropriate parameter to accelerate the 3D T1W-TFE (65% time reduction) with preserved visual image quality. The voxel-based analysis demonstrated high ICCs for brain volume measurements in the majority of brain regions, implying the feasibility of the accelerated technique.

Diagnostic assessment of magnetic resonance imaging for patients with intralabyrinthine schwannoma: A systematic review

OBJECTIVES

Recent advancements in high-resolution imaging have improved the diagnostic assessment of magnetic resonance imaging (MRI) for intralabyrinthine schwannoma (ILS). This systematic review aimed to evaluate the diagnostic performance of MRI for patients with ILS.

METHODS

Ovid-MEDLINE and EMBASE databases were searched for related studies on the diagnostic performance of MRI for patients with ILS published up to February 10, 2020. The primary endpoint was the diagnostic performance of MRI for ILS. The quality of the enrolled studies was assessed using tailored questionnaires and the Quality Assessment of Diagnostic Accuracy Studies-2 criteria.

RESULTS

Overall, 6 retrospective studies that included 122 patients with ILS from a parent population of 364 were included. The sample size, parent population and its composition, reference standard, detailed parameters of MRI, and even the diagnostic methods varied between the studies. The studies had moderate quality. The sensitivity of combination of T2WI and CE-T1WI was over 90%. Relative sensitivity of T2WI comparative to CE-T1WI ranged from 62% to 100%, and the specificity were 100%.

CONCLUSIONS

MRI has acceptable diagnostic performance for ILS. There is a need for well-organized research to reduce the factors causing heterogeneity.

Technical Improvements in Head and Neck MR Imaging: At the Cutting Edge

Head and neck MR imaging is technically challenging because of magnetic field inhomogeneity, respiratory and swallowing motion, and necessity of high-resolution imaging to trace key anatomic structures. These challenges have been answered by advances in MR imaging technology, including isovolumetric three-dimensional imaging, robust fat-water separation techniques, and novel deep learning-based reconstruction algorithms. New applications of MR imaging have been advanced and functional imaging has been improved. Improvements in acquisition and reconstruction technique facilitate novel applications of morphologic and functional imaging. This results in opportunities to improve diagnosis, staging, and treatment selection through application of advanced MR imaging techniques.

Acceleration of Double Inversion Recovery Sequences in Multiple Sclerosis With Compressed Sensing

OBJECTIVE

The aim of this study was to assess the performance of double inversion recovery (DIR) sequences accelerated by compressed sensing (CS) in a clinical setting.

MATERIALS AND METHODS

We included 106 patients with MS (62 female [58%]; mean age, 44.9 ± 11.0 years) in this prospective study. In addition to a full magnetic resonance imaging protocol including a conventional SENSE accelerated DIR, we acquired a CS DIR (time reduction, 51%). We generated subtraction maps between the two DIR sequences to visualize focal intensity differences. Two neuroradiologists independently assessed these maps for intensity differences, which were categorized into definite MS lesions, possible lesions, or definite artifacts. Counts of focal intensity differences were compared using a Wilcoxon rank sum test. Moreover, conventional lesion counts were acquired for both sequences in independent readouts, and agreement between the DIR variants was assessed with intraclass correlation coefficients.

RESULTS

No hyperintensity that was rated as definite lesion was missed in the CS DIR. Two possible lesions were only detected in the conventional DIR, one only in the CS DIR (no significant difference, P = 0.57). The conventional DIR showed significantly more definite artifacts within the white matter (P = 0.024) and highly significantly more at the cortical-sulcal interface (P < 0.001). For both readers, intraclass correlation coefficient between the lesion counts in the two DIR variants was near perfect (0.985 for reader 1 and 0.981 for reader 2).

CONCLUSIONS

Compressed sensing can be used to substantially reduce scan time of DIR sequences without compromising diagnostic quality. Moreover, the CS accelerated DIR proved to be significantly less prone to imaging artifacts.