Fast Field Echo Research Articles

High-resolution magnetic resonance imaging of the triangular fibrocartilage complex using compressed sensing sensitivity encoding (SENSE)

PurposeTo evaluate the optimal sequence for high-resolution magnetic resonance imaging (MRI) of the triangular fibrocartilage complex (TFCC) using compressed sensing-sensitivity encoding (CS-SENSE). MethodsThree-dimensional fast field echo T2-weighted images were obtained from 13 healthy volunteers using the original, high spatial resolution sequence with CS-SENSE [HR (CS-SENSE)] and without CS-SENSE (HR) and super-high spatial resolution sequence with CS-SENSE [S-HR (CS-SENSE)] and without CS-SENSE (S-HR). For qualitative analysis, the number of patients affected by motion artifacts in each sequence was counted, and the visualization of the TFCC anatomic structures and overall image quality were categorized. For the quantitative analysis, relative signal intensity (SI) and relative contrast of the lunate bone marrow, lunate cartilage, and disk proper in the wrist joint were all calculated. ResultsThe HR (CS-SENSE) sequence showed better visualization scores than the original sequence in the triangular ligament at the ulnar styloid tip, dorsal radioulnar ligament, and ulnotriquetral ligament. Similarly, the S-HR (CS-SENSE) sequence showed better visualization scores than the original sequence in the triangular ligament at the ulnar styloid tip and dorsal radioulnar ligament. Overall image quality scores were not significantly different, and motion artifacts in the HR and S-HR sequences were observed in 3 of the 13 patients. In contrast, the original sequence showed higher values than those in the HR (CS-SENSE) and S-HR (CS-SENSE) sequences in relative SI of the bone marrow and relative contrast of the cartilage-bone marrow and cartilage-disk proper. ConclusionsOut of the three sequences, the HR (CS-SENSE) sequence provided the highest visualization score and diagnostically sufficient image quality score, although relative SI and relative contrast were low. The HR (CS-SENSE) sequence may be clinically useful for imaging TFCCs.

Comparative Analysis of Blood T2 Values Measured by T2 -TRIR and TRUST.

Venous blood oxygenation (Yv), which can be derived from venous blood T2 (T2 b), combined with oxygen-extraction fraction (OEF) and cerebral metabolic rate of oxygen, is considered indicative for tissue viability and brain functioning and frequently assessed in patients with sickle cell disease. Recently, T2 -Prepared-Blood-Relaxation-Imaging-with-Inversion-Recovery (T2 -TRIR) was introduced allowing for simultaneous measurements of blood T2 and T1 (T1 b), potentially improving Yv estimation by overcoming the need to estimate hematocrit. To optimize and compare T2 -TRIR with T2 -relaxation-under-spin-tagging (TRUST) sequence. Prospective. A total of 12 healthy volunteers (six female, 27 ± 3 years old) and 7 patients with sickle cell disease (five female, 32 ± 12 years old). 3 T; turbo field echo planar imaging (TFEPI), echo planar imaging (EPI), and fast field echo (FFE). T2 b, Yv, and OEF from TRUST and T2 -TRIR were compared and T2 -TRIR-derived T1 b was assessed. Within- and between-session repeatability was quantified in the controls, whereas sensitivity to hemodynamic changes after acetazolamide (ACZ) administration was assessed in the patients. Shapiro-Wilk, one-sample and paired-sample t-test, repeated measures ANOVA, mixed linear model, Bland-Altman analysis and correlation analysis. Sidak multiple-comparison correction was performed. Significance level was 0.05. In controls, T2 b from T2 -TRIR (70 ± 11 msec) was higher compared to TRUST (60 ± 8 msec). In patients, T2 b values were lower pre- compared to post-ACZ administration (TRUST: 80 ± 15 msec and 106 ± 23 msec and T2 -TRIR: 95 ± 21 msec and 125 ± 36 msec). Consequently, Yv and OEF were lower and higher pre- compared to post-ACZ administration (TRUST Yv: 68% ± 7% and 77% ± 8%, T2 -TRIR Yv: 74% ± 8% and 80% ± 6%, TRUST OEF: 30% ± 7% and 21% ± 8%, and T2 -TRIR OEF: 25% ± 8% and 18% ± 6%). TRUST and T2 -TRIR are reproducible, but T2 -TRIR-derived T2 b values are significantly higher compared to TRUST, resulting in higher Yv and lower OEF estimates. This bias might be considered when evaluating cerebral oxygen homeostasis. 2 TECHNICAL EFFICACY: Stage 2.

Constrained Ellipse Fitting for Efficient Parameter Mapping With Phase-Cycled bSSFP MRI.

Balanced steady-state free precession (bSSFP) imaging enables high scan efficiency in MRI, but differs from conventional sequences in terms of elevated sensitivity to main field inhomogeneity and nonstandard [Formula: see text]-weighted tissue contrast. To address these limitations, multiple bSSFP images of the same anatomy are commonly acquired with a set of different RF phase-cycling increments. Joint processing of phase-cycled acquisitions serves to mitigate sensitivity to field inhomogeneity. Recently phase-cycled bSSFP acquisitions were also leveraged to estimate relaxation parameters based on explicit signal models. While effective, these model-based methods often involve a large number of acquisitions (N ≈ 10-16), degrading scan efficiency. Here, we propose a new constrained ellipse fitting method (CELF) for parameter estimation with improved efficiency and accuracy in phase-cycled bSSFP MRI. CELF is based on the elliptical signal model framework for complex bSSFP signals; and it introduces geometrical constraints on ellipse properties to improve estimation efficiency, and dictionary-based identification to improve estimation accuracy. CELF generates maps of [Formula: see text], [Formula: see text], off-resonance and on-resonant bSSFP signal by employing a separate [Formula: see text] map to mitigate sensitivity to flip angle variations. Our results indicate that CELF can produce accurate off-resonance and banding-free bSSFP maps with as few as N = 4 acquisitions, while estimation accuracy for relaxation parameters is notably limited by biases from microstructural sensitivity of bSSFP imaging.

The Usefulness of Intraoral Ultrasonography and Post-Contrast Three-Dimensional Fast Field Echo Imaging in the Evaluation of Radiological Depth of Invasion of Oral Tongue Squamous Cell Carcinoma: Comparison with Pathological Depth of Invasion Assessment

Aim Squamous cell carcinoma (SCC) is the most common malignancy in the oral tongue. Depth of invasion (DOI) of the tongue SCC is known as a predictor of recurrence and survival in patients. Both intraoral ultrasonography (ioUS) and post-contrast three-dimensional fast field echo (3D-FFE) imaging are useful for predicting pathological DOI and can contribute to effective treatment plans and a positive prognosis. The purpose of this study was to evaluate the usefulness of ioUS in comparison with post-contrast 3D-FFE imaging for assessing radiological DOI and compare radiological DOI and pathological DOI in patients with oral tongue SCC. Methods Fifteen patients were included in this study conducted between August 2018 and March 2020. Spearman's rank correlation coefficient was used to compare radiological DOI with pathological DOI. Results Both ioUS-derived DOI (9.98 mm) and 3D-FFE-derived DOI (9.86 mm) were larger than pathological DOI (5.7 mm). The Pearson’s correlation coefficient (PCC) between ioUS-derived DOI and pathological DOI was 0.63 and between 3D-FFE-derived DOI and pathological DOI was 0.58.

Longitudinal Changes in Left Ventricular Blood Flow Kinetic Energy After Myocardial Infarction: Predictive Relevance for Cardiac Remodeling.

Four-dimensional (4D) flow cardiac magnetic resonance (cardiac MR) imaging provides quantification of intracavity left ventricular (LV) flow kinetic energy (KE) parameters in three dimensions. ST-elevation myocardial infarction (STEMI) patients have been shown to have altered intracardiac blood flow compared to controls; however, how 4D flow parameters change over time has not been explored previously. Measure longitudinal changes in intraventricular flow post-STEMI and ascertain its predictive relevance of long-term cardiac remodeling. Prospective. Thirty-five STEMI patients (M:F = 26:9, aged 56 ± 9 years). A 3 T/3D EPI-based, fast field echo (FFE) free-breathing 4D-flow sequence with retrospective cardiac gating. Serial imaging at 3-7 days (V1), 3-months (V2), and 12-months (V3) post-STEMI, including the following protocol: functional imaging for measuring volumes and 4D-flow for calculating parameters including systolic and peakE-wave LVKE, normalized to end-diastolic volume (iEDV) and stroke volume (iSV). Data were analyzed by H.B. (3 years experience). Patients were categorized into two groups: preserved ejection fraction (pEF, if EF > 50%) and reduced EF (rEF, if EF < 50%). Independent sample t-tests were used to detect the statistical significance between any two cohorts. P < 0.05 was considered statistically significant. Across the cohort, systolic KEisv was highest at V1 (28.0 ± 4.4μJ/mL). Patients with rEF retained significantly higher systolic KEisv than patients with pEF at V2 (18.2 ± 3.4μJ/mL vs. 6.9 ± 0.6μJ/mL, P < 0.001) and V3 (21.6 ± 5.1μJ/mL vs. 7.4 ± 0.9μJ/mL, P < 0.001). Patients with pEF had significantly higher peakE-wave KEiEDV than rEF patients throughout the study (V1: 25.4 ± 11.6μJ/mL vs. 18.1 ± 9.9μJ/mL, P < 0.03, V2: 24.0 ± 10.2μJ/mL vs. 17.2 ± 12.2μJ/mL, P < 0.05, V3: 27.7 ± 14.8μJ/mL vs. 15.8 ± 7.6μJ/mL, P < 0.04). Systolic KE increased acutely following MI; in patients with pEF, this decreased over 12months, while patients with rEF, this remained raised. Compared to patients with pEF, persistently lower peakE-wave KE in rEF patients is suggestive of early and fixed impairment in diastolic function. 1 TECHNICAL EFFICACY: Stage 3.

Clinical Evaluation of Left Ventricular Diastolic Function Using Phase-contrast Cine Cardiovascular Magnetic Resonance Imaging: A Comparison With Steady-state Free Precession Cine Cardiovascular Magnetic Resonance Imaging and Echocardiography.

We investigated a practical method using phase-contrast (PC) cine cardiovascular magnetic resonance imaging to estimate peak filling rate and early/atrial velocity (E/A) as left ventricular diastolic function indicators. Peak filling rate and E/A were estimated in 32 patients using PC imaging with high spatial or high temporal resolution and compared with those estimated using steady-state free precession cine cardiovascular magnetic resonance imaging and echocardiography. Peak filling rate estimated using PC imaging significantly correlated with those estimated using steady-state free precession imaging despite apparent underestimation using PC imaging with high spatial resolution. The E/A estimated using PC imaging significantly correlated with those estimated using echocardiography. Peak filling rate and E/A measurements using PC imaging with high temporal resolution is convenient and acceptably accurate, suggesting its potential for clinical use.

Insights into diastolic function analyses using cardiac magnetic resonance imaging: impact of trabeculae and papillary muscles

BackgroundThis cardiovascular magnetic resonance (CMR) study investigates the impact of trabeculae and papillary muscles (TPM) on diastolic function parameters by differentiation of the time-volume curve. Differentiation causes additional problems, which is overcome by standardization.MethodsCine steady-state free-precession imaging at 1.5 T was performed in 40 healthy volunteers stratified for age (age range 7–78y). LV time-volume curves were assessed by software-assisted delineation of endocardial contours from short axis slices applying two different methods: (1) inclusion of TPM into the myocardium and (2) inclusion of TPM into the LV cavity blood volume. Diastolic function was assessed from the differentiated time-volume curves defining the early and atrial peaks, their filling rates, filling volumes, and further dedicated diastolic measures, respectively.ResultsOnly inclusion of TPM into the myocardium allowed precise assessment of early and atrial peak filling rates (EPFR, APFR) with clear distinction of EPFR and APFR expressed by the minimum between the early and atrial peak (EAmin) (100% vs. 36% for EAmin < 0.8). Prediction of peak filling rate ratios (PFRR) and filling volume ratios (FVR) by age was superior with inclusion of TPM into the myocardium compared to inclusion into the blood pool (r2 = 0.85 vs. r2 = 0.56 and r2 = 0.89 vs. r2 = 0.66). Standardization problems were overcome by the introduction of a third phase (mid-diastole, apart from diastole and systole) and fitting of the early and atrial peaks in the differentiated time-volume curve.ConclusionsOnly LV volumetry with inclusion of TPM into the myocardium allows precise determination of diastolic measures and prevents methodological artifacts.

Deep Learning Auto-Segmentation on Multi-Sequence MRI for MR-Guided Adaptive Radiation Therapy

<h3>Purpose/Objective(s)</h3> Robust auto-segmentation based on daily MRI is highly desirable for MR-guided adaptive radiation therapy (MRgART). However, it is generally challenging particularly if the daily MRI is acquired with multiple sequences or if it is for imaging complex anatomy, e.g., abdomen. To overcome these issues, we developed a deep learning algorithm to segment abdominal organs quickly and automatically on multi-sequence MRI. <h3>Materials/Methods</h3> The deep learning auto-segmentation model was developed using a modified U-net, ResUnet3D, with end-to-end mapping, and was trained with 85 daily MRI sets acquired during MRgART on a 1.5T MR-Linac for 37 patients with abdominal tumors. The daily MRI sets were motion averaged images derived from 4D MRI acquired with multiple sequences, including Fast Field Echo (FFE), Balanced Turbo Field Echo (BTFE) and TFE. Each daily MRI was paired with a CT. All MRIs were pre-processed using bias field correction and intensity standardization. The ground truth contours were created manually based on existing guidelines. For the training datasets, field-of-view extension via online random 3D elastic transform/deformation was utilized to augment and improve the quality of datasets. During the model training, a patient-based z-score normalization method was employed to standardize the multi-contrast images. Two models were trained, one for 11 organs: aorta, duodenum, kidneys, liver, pancreas, spinal cord, spleen, stomach, large bowel, and small bowel, and another for 10 organs with combined large and small bowel. Performance of the obtained models was evaluated using 11 test datasets in terms of dice similarity coefficient (DSC), mean distance to agreement (MDA) and time efficiency using an Intel Xeon CPU (2.4 GHz, 64GB RAM) hardware. <h3>Results</h3> For the challenging bowels, the auto-segmentation accuracy for the model trained with the combined bowel was better, with MDA/DSC of 2.1/0.86 versus 6.8/0.76 (large bowel) and 6.1/0.68 (small bowel) for the separate-bowel model. Average DSC for the obtained contours of aorta, left kidney, right kidney, liver, spinal cord, spleen, and stomach was 0.93, 0.93, 0.94, 0.94, 0.83, 0.92 and 0.88, respectively from both models. While no significant difference in model performance was observed with BTFE versus TFE testing datasets, a slightly improved segmentation was seen on the BTFE images for pancreas and duodenum, DSC 0.71 and 0.72. This improvement may be attributed to the enhanced contrast seen in BTFE images when compared to the TFE and FFE images. The time required to generate all organs on an MRI was 20-24 seconds. <h3>Conclusion</h3> We have developed deep learning auto-segmentation models based on multi-sequence MRI sets for abdominal organs. The models performed reasonably well. With further development using large datasets, the models may be integrated in MRgART for fast, fully automated, and accurate contouring of abdominal organs on daily MRI.

Deep Learning Reconstruction Helps to Achieve Diagnostic-like Image Quality in MR Radiation Therapy of Brain

Deep Learning Reconstruction Helps to Achieve Diagnostic-like Image Quality in MR Radiation Therapy of Brain

Cross-sectional imaging of popliteal artery entrapment syndrome

A 63-year-old asymptomatic man with unlimited exercise tolerance is investigated for suspected popliteal aneurysms, due to absent pedal pulses and prominent popliteal pulsations. Contrast-enhanced computed tomography (CT) shows occlusion of the left popliteal artery with geniculate collaterals surrounding the popliteal vein (A). The medial head of gastrocnemius separates the popliteal vein and the occluded (entrapped) popliteal artery. CT also shows entrapment of the right popliteal artery, due to extrinsic compression by the abnormally sited tendon of the medial head of gastrocnemius, which separates the artery and vein, mirroring the muscular anatomy on the left (B). A second 55-year-old man, normally walking 10-12 miles per day without restriction, presents with acute right leg claudication at 200 m. Contrast-enhanced CT demonstrates left popliteal artery stenosis with post-stenotic dilatation and right distal popliteal embolic occlusion due to a popliteal aneurysm with thrombus secondary to bilateral popliteal entrapment syndrome (PAES) (C). Axial balanced flow fast field echo magnetic resonance images and corresponding CT axial images demonstrate that the left medial head of gastrocnemius passes between the popliteal artery and popliteal vein. However, the aneurysmal right popliteal artery and the right popliteal vein are both located medial to, and are not separated by, the medial head of gastrocnemius (D). PAES is an uncommon cause of occlusive arterial disease, which is often bilateral. It is caused either by abnormal muscular insertions, typically of the medial head of gastrocnemius or the popliteus muscle, or by anomalous fibrous bands (types II, III, and IV, according to the modified Whelan classification).1Rich N.M. Collins G.J. McDonald P.T. Kozloff L. Clagett G.P. Collins J.T. Popliteal vascular entrapment: its increasing interest.Arch Surg. 1979; 114: 1377-1384Google Scholar Less commonly, an abnormal course of the popliteal vessels around normally inserted muscles is responsible for the entrapment (type I). Arteriovenous (type V) and functional entrapments have also been described. As illustrated, cross-sectional studies are very useful in demonstrating the abnormal anatomy. These two cases also show that muscular abnormalities are not always symmetrical in bilateral PAES (all limbs presenting as type II, except for the right leg of the second patient, which can be classed as type I, due to the medial course of the artery around a normal insertion of the medial head of gastrocnemius). Both patients consented to the publication of the case details and relative images.

Normal values for paediatric biventricular volumes, ejection fraction and mass – influence of cardiovascular magnetic resonance analysis techniques

Abstract Background Measurement of ventricular volumes and function by steady-state free precession (SSFP) cardiovascular magnetic resonance (CMR) is an important diagnostic tool in the treatment and follow-up of paediatric congenital heart disease. However, normal values are rare and the CMR analysis methods are inconsistent. Aims We sought to create two sets of ventricular normal values for different CMR analysis (contouring) methods. Methods In a retrospective study design, CMR data sets of 154 healthy children with an age range between 4 and 18 years from two centers in the UK and Germany were evaluated. Left and right ventricular end-diastolic and end-systolic volumes (LVEDV, LVESV, RVEDV, RVESV), ejection fraction (RVEF, LVEF) and myocardial mass (LVMM, RVMM) were analysed from short axis steady-state free precession images by using two different analysis techniques: 1) papillary muscles, myocardial trabeculations and the moderator band were included in the ventricular volume and excluded from the ventricular mass (Figure 1), 2) papillary muscles, myocardial trabeculations and the moderator band were excluded from the ventricular volume and included in the ventricular mass (Figure 2). Sex-specific reference curves were created separately for both ventricular contouring methods using the lambda mu sigma method. Correlations between variables were analyzed with the Spearman's rank correlation. Contouring methods were compared through Bland-Altman analysis. Results The mean age was 13.85±2.8 years (53 girls). In children from 4 to 10 years average ventricular volumes and mass normalized for body surface area (BSA) measured: In children from 11 to 18 years average ventricular volumes and mass measured: Separate centile charts and centile tables for boys and girls for all cardiac parameters were created. Conclusion We provide paediatric CMR reference values for biventricular volumes, ejection and masses for two different CMR contouring methods. They can be used in the diagnosis and follow-up of congenital or acquired heart disease in children and for research purposes. Funding Acknowledgement Type of funding sources: None. Figure 1Figure 2

541 - MRI-BASED MEASUREMENT OF HIPPOCAMPAL VOLUME IN PATIENTS WITH DEMENTIA

Background:Dementia due to probable Alzheimer’s disease (AD) represents between 60 and 80% of all dementias. The total number of estimated AD cases worldwide by 2030 is 65.7 million and 115.4 million by 2050; this represents a twofold population increase in the next 20 years.Magnetic resonance imaging (MRI) has been the primary tool of interest to link hippocampal volume loss with dementia firmly.MRI-based volumetry has been proposed as a promising biomarker.Hippocampal volumetry is useful in discriminating not only cognitively normal individuals from those with dementia but can also differentiate Mild Cognitive Impairment (MCI) from various types of dementia.Research objective:To measure hippocampal volume in various types of dementia. (MMSE) and Activities of daily living (ADL) in patients with dementia.Method:A cross-sectional study conducted for period of one year among 21 patients with Alzheimer’s, vascular dementia, amnestic mild cognitive impairment and 20 healthy age matched controls. MMSE scale was used to stratify patients on cognitive function impairments. ADL scale to assess functional status of the patient ability to perform activities of daily living independently in diverse settings. Hippocampal volume measured using MRI 1.5 T Philips Ingenia, a coronal T1-weighted FFE (Fast Field Echo) 3D sequence.Results:Total Hippocampal volume was reduced by 35% in Alzheimer’s disease, 27% in vascular dementia and 10% in amnestic mild cognitive impairment, compared with control groupConclusions:Moderate positive correlation between mean total hippocampal volume and MMSE scores in patients with dementia which was statistically significant. (P value= 0.001).

Differentiation of Diffuse Infiltration Pattern in Multiple Myeloma From Hyperplastic Hematopoietic Bone Marrow: Qualitative and Quantitative Analysis Using Whole-Body MRI.

The visual assessment used for diffuse infiltration of multiple myeloma (MM) is inadequate. It can be difficult to differentiate MM from hyperplastic hematopoietic bone marrow (HHBM) because the MRI signal characteristics overlap. To analyze the bone marrow diffuse signal changes on whole-body MRI caused by MM and HHBM. Retrospective. Thirty Four patients with MM (21 men and 13 women), 22 patients with HHBM (9 men and 13 women), and 15 healthy controls (9 men and 6 women). A 3.0 T MRI; diffusion-weighted whole-body imaging with background body signal suppression (DWIBS), modified Dixon T1 fast field echo, and T2 STIR. Three radiologists analyzed the whole-body MRI alone and in combination with apparent diffusion coefficient (ADC) and fat fraction (FF) with qualitative and quantitative analysis. Normalized T1 and T2 signal intensities (nT1 and nT2) and signal-to-noise ratio (SNR) were obtained. Kruskal-Wallis and chi-square tests. The MM group had significantly higher ADC and significantly lower FF than HHBM and control groups. There was no significant difference in nT1, nT2 or SNR between MM and HHBM (P=0.932, P=0.097, and P=0.110, respectively). Receiver operating characteristic (ROC) analysis using ADC and FF cut-off values of 0.47 × 10-3 mm2 /sec and 20.63%, respectively. The AUC was 0.866 for ADC and 0.886 for FF. The quantitative analysis yielded better specificity (observer 1: 81.8% vs. 27.3%; observer 2: 68.2% vs. 22.7%; and observer 3: 72.7% vs. 18.2%) and a higher diagnostic accuracy (observer 1: 82.1% vs. 51.8%; observer 2: 80.4% vs. 50.0%; observer 3: 76.8% vs. 44.6%) than the qualitative analysis. Whole-body MRI combined with DWIBS and mDIXON could be used to differentiate between MM and HHBM. Combining the quantitative ADC and FF with the whole-body MRI improved the specificity and accuracy in differentiating these conditions. 3 TECHNICAL EFFICACY: Stage 2.

State of the art of magnetic resonance imaging ( MRI ) in evaluation of focal hepatic lesions

Background: The recent developments in (MRI) sequences for the upper abdomen comprise unenhanced diffusion-weighted imaging (DWI), and (DCE) MRI. DWI allows improved detection of small (< 10 mm) focal liver lesions and useful as a road map sequence. The aim of this work was to study recent and advanced magnetic resonance imaging (MRI) techniques in the evaluation of focal hepatic lesions. Methods: this study included 40 patients, patients underwent assessment with recent MRI sequences (DWI), DCE MRI, T2-weighted imaging, steady-state free precession (SSFP) imaging and T1 in-phase/out-phase imaging. Results: Half of the studied patients were females. Age ranged from 30 to 67 years with mean 48.825 years. Forty percent of patients had right-side lesion while 22.5% had left side lesion. On HPE of the studied patients, 52.5% had malignant growth while the remaining 47.5% had benign lesions. About 23% had HCC. One fifth had hemorrhagic cyst and the same percentage had metastatic lesion. Adenoma was present in 7.5%, There is statistically significant relation between nature of foci and ADC value (significantly higher in benign lesions). ROC curve of ADC in diagnosis of benign nature of focal hepatic masses among the studied patients; area under curve 0.945, (p < 0.05). Conclusion: diffusion-weighted MRI sequence with quantitative ADC measurements should be used as an additional sequence to supplement conventional MRI protocol studies for proper detection (using low b values) and characterization (using high b values) of focal liver lesions

Compressed-sensing accelerated magnetic resonance imaging of inner ear.

ObjectiveTo compare conventional method and compressed‐sensing (CS) accelerated 3D balanced fast field echo imaging (bFFE) of inner ear.MethodsTwenty 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.ResultsThe 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.ConclusionsThe CS‐bFFE improves image quality and reduces acquisition time significantly, and it is a feasible MRI protocol for inner ear imaging.

Blood oxygenation level-dependent MRI at 3T for differentiating prostate cancer from benign tissue: a preliminary experience.

Blood oxygenation-level dependent (BOLD) MRI may identify or quantify the regional distribution of hypoxia within a tumor. We aimed to evaluate the feasibility of BOLD MRI at 3 T in differentiating prostate cancer from benign tissue. A total of 145 patients with biopsy-proven prostate cancer underwent BOLD MRI at 3 T. BOLD MRI was performed using a multiple fast field echo sequence to acquire 12 T2*-weighted images. The R2* value (rate of relaxation, s-1) was measured in the index tumor, and benign peripheral (PZ) and transition zone (TZ), and the results were compared. The variability of R2* measurements was evaluated. Tumor R2* values (25.95 s-1) were significantly different from the benign PZ (27.83 s-1) and benign TZ (21.66 s-1) (p < 0.001). For identifying the tumor, the area under the receiver operating characteristic of R2* was 0.606, with an optimal cut-off value of 22.8 s-1 resulting in 73.8% sensitivity and 52% specificity. In the Bland-Altman test, the mean differences in R2* values were 8.5% for tumors, 13.3% for benign PZ, and 6.8% for benign TZ. No associations between tumor R2* value and Gleason score, age, prostate volume, prostate-specific antigen, or tumor size. BOLD MRI at 3 T appears to be a feasible tool for differentiating between prostate cancer and benign tissue. However, further studies are required for a direct clinical application. The R2* values are significantly different among prostate cancer, benign PZ, and benign TZ.

Unraveling the MRI-Based Microstructural Signatures Behind Primary Progressive and Relapsing-Remitting Multiple Sclerosis Phenotypes.

BackgroundThe mechanisms driving primary progressive and relapsing–remitting multiple sclerosis (PPMS/RRMS) phenotypes are unknown. Magnetic resonance imaging (MRI) studies support the involvement of gray matter (GM) in the degeneration, highlighting its damage as an early feature of both phenotypes. However, the role of GM microstructure is unclear, calling for new methods for its decryption.PurposeTo investigate the morphometric and microstructural GM differences between PPMS and RRMS to characterize GM tissue degeneration using MRI.Study TypeProspective cross‐sectional study.SubjectsForty‐five PPMS (26 females) and 45 RRMS (32 females) patients.Field Strength/Sequence3T scanner. Three‐dimensional (3D) fast field echo T1‐weighted (T1‐w), 3D turbo spin echo (TSE) T2‐w, 3D TSE fluid‐attenuated inversion recovery, and spin echo‐echo planar imaging diffusion MRI (dMRI).AssessmentT1‐w and dMRI data were employed for providing information about morphometric and microstructural features, respectively. For dMRI, both diffusion tensor imaging and 3D simple harmonics oscillator based reconstruction and estimation models were used for feature extraction from a predefined set of regions. A support vector machine (SVM) was used to perform patients' classification relying on all these measures.Statistical TestsDifferences between MS phenotypes were investigated using the analysis of covariance and statistical tests (P < 0.05 was considered statistically significant).ResultsAll the dMRI indices showed significant microstructural alterations between the considered MS phenotypes, for example, the mode and the median of the return to the plane probability in the hippocampus. Conversely, thalamic volume was the only morphometric feature significantly different between the two MS groups. Ten of the 12 features retained by the selection process as discriminative across the two MS groups regarded the hippocampus. The SVM classifier using these selected features reached an accuracy of 70% and a precision of 69%.Data ConclusionWe provided evidence in support of the ability of dMRI to discriminate between PPMS and RRMS, as well as highlight the central role of the hippocampus.Level of Evidence2Technical Efficacy Stage3

MR compatibility, safety and accuracy of the redesigned UMC Utrecht single needle implant device

Purpose. The Utrecht single needle implant device (SNID) was redesigned to increase needle insertion velocity. The purpose of this study is to evaluate the magnetic resonance compatibility, safety and accuracy of the implant device preparing its application in a patient study to investigate the feasibility of inserting a brachytherapy needle into the prostate to a defined tumor target point. Methods. Several experiments were performed to evaluate the mechanical and radiofrequency safety of the needle system, the magnetic field perturbation, the calibration of the implant device in the MR coordinate system, functioning of the implant device during imaging and accuracy of needle insertion. Results. Endurance experiments showed the mechanical safety of the needle system. Magnetic field perturbation was acceptable with induced image distortions smaller than 0.5 mm for clinical MR sequences. Calibration of the implant device in the MR coordinate system was reproducible with average error (mean±standard deviation) of 0.2 ± 0.4 mm, 0.1 ± 0.3 mm and 0.6 ± 0.6 mm in the x, y- and z- direction, respectively. The RF safety measurement showed for clinical MR imaging sequences maximum temperature rises of 0.2 °C at the entry and tip points of the needle. Simultaneous functioning of the implant device and imaging is possible albeit with some intensity band artifacts in the fast field echo images. Finally, phantom measurements showed deviations amounting 2.5–3.6 mm measured as target-to-needle distance at a depth of 12 cm. Conclusions. This preclinical evaluation showed that the MR compatibility, safety and accuracy of the redesigned UMC Utrecht SNID allow its application in a patient study on the feasibility of inserting a brachytherapy needle into the prostate to a defined tumor target point.

Correlations between peripheral levels of inflammatory mediators and frontolimbic structures in bipolar disorder: an exploratory analysis.

Altered peripheral immune/inflammatory system and brain volumetric changes have been implicated in the pathophysiology of bipolar disorder (BD). This study aimed to evaluate how peripheral levels of cytokines are related to volumetric brain changes in euthymic patients with BD. Euthymic patients with BD (n=21) and healthy controls (n=22) were enrolled in this exploratory study. Blood samples were collected on the same day of clinical assessment and neuroimaging. Cytokines were measured through cytometric bead array method. Neuroimaging data were acquired using a sagittal three-dimensional magnetic resonance imaging T1-weighted fast field echo sequence and was processed using FreeSurfer. Compared to controls, BD patients had significantly lower volumes in the cingulate, medial-orbitofrontal (MOF) and parahippocampal regions. We found a negative correlation between right MOF volume and interferon-gamma levels (β=-0.431, P=.049) and a positive correlation between interleukin-10 levels and left posterior cingulate volume (β=0.457, P=.048). Our results support the involvement of inflammatory pathways in structural brain changes in BD.

Varying undersampling directions for accelerating multiple acquisition magnetic resonance imaging.

In this study, we propose a new sampling strategy for efficiently accelerating multiple acquisition MRI. The new sampling strategy is to obtain data along different phase-encoding directions across multiple acquisitions. The proposed sampling strategy was evaluated in multicontrast MR imaging (T1, T2, proton density) and multiple phase-cycled (PC) balanced steady-state free precession (bSSFP) imaging by using convolutional neural networks with central and random sampling patterns. In vivo MRI acquisitions as well as a public database were used to test the concept. Based on both visual inspection and quantitative analysis, the proposed sampling strategy showed better performance than sampling along the same phase-encoding direction in both multicontrast MR imaging and multiple PC-bSSFP imaging, regardless of sampling pattern (central, random) or datasets (public, retrospective and prospective in vivo). For the prospective in vivo applications, acceleration was performed by sampling along different phase-encoding directions at the time of acquisition with a conventional rectangular field of view, which demonstrated the advantage of the proposed sampling strategy in the real environment. Preliminary trials on compressed sensing (CS) also demonstrated improvement of CS with the proposed idea. Sampling along different phase-encoding directions across multiple acquisitions is advantageous for accelerating multiacquisition MRI, irrespective of sampling pattern or datasets, with further improvement through transfer learning.