Volumetric Interpolated Breath-hold Research Articles

Fast magnetic resonance arthrography of the labrum

Research question: Short volumetric interpolated breath hold exam (VIBE) 3D gradient echo sequences are comparable to T1 spin echo (SE) sequences for evaluating the shoulder labrum using arthroscopy as a gold standard. Methods: 24 patients with suspected labral tears had magnetic resonance (MR) arthrography of the shoulder using 1.5T MR scanner. Coronal oblique 3D VIBE FS sequences were performed and reconstructed in axial and sagittal oblique planes and compared with standard T1 SE sequences. Presence and location of labral tear and rotator cuff tears were noted. Findings were correlated with surgery where available. Time to obtain T1 SE sequences versus 3D VIBE acquisition was recorded. Results: Of 24 patients, 54% had arthroscopy. Sensitivity and positive predictive value (PPV) of both T1 SE and VIBE sequences for labral tears was 92%. 100% agreement for diagnosis of labral tear by readers between both sequences was noted. Specific labral tear location was accurate in 75% for both sequences. The mean time to obtain T1 SE sequences was 13.5 mins and 7.5 minutes for 3D VIBE sequences. Conclusion: Fast MR arthrography using 3D VIBE sequences shows excellent concordance with standard T1-FS sequence for diagnosis of labral tears. With shorter acquisition time and high diagnostic sensitivity 3D VIBE sequences maybe used as an alternative to standard sequences. Level of evidence: Level III retrospective diagnostic study.

Differences between 3D isovoxel fat suppression VIBE MRI and CT models of proximal femur osseous anatomy: A preliminary study for bone tumor resection planning.

To evaluate the osseous anatomy of the proximal femur extracted from a 3D-MRI volumetric interpolated breath-hold (VIBE) sequence using either a Dixon or water excitation (WE) fat suppression method, and to measure the overall difference using CT as a reference standard. This retrospective study reviewed imaging of adult patients with hip pain who underwent 3D hip MRI and CT. A semi-automatically segmented CT model served as the reference standard, and MRI segmentation was performed manually for each unilateral hip joint. The differences between Dixon-VIBE-3D-MRI vs. CT, and WE-VIBE-3D-MRI vs. CT, were measured. Equivalence tests between Dixon-VIBE and WE-VIBE models were performed with a threshold of 0.1 mm. Bland-Altman plots and Lin's concordance-correlation coefficient were used to analyze the agreement between WE and Dixon sequences. Subgroup analyses were performed for the femoral head/neck, intertrochanteric, and femoral shaft areas. The mean and maximum differences between Dixon-VIBE-3D-MRI vs. CT were 0.2917 and 3.4908 mm, respectively, whereas for WE-VIBE-3D-MRI vs. CT they were 0.3162 and 3.1599 mm. The mean differences of the WE and Dixon methods were equivalent (P = 0.0292). However, the maximum difference was not equivalent between the two methods and it was higher in WE method. Lin's concordance-correlation coefficient showed poor agreement between Dixon and WE methods. The mean differences between the CT and 3D-MRI models were significantly higher in the femoral shaft area (P = 0.0004 for WE and P = 0.0015 for Dixon) than in the other areas. The maximum difference was greatest in the intertrochanteric area for both techniques. The difference between 3D-MR and CT models were acceptable with a maximal difference below 3.5mm. WE and Dixon fat suppression methods were equivalent. The mean difference was highest at the femoral shaft area, which was off-center from the magnetization field.

Fully automated multiorgan segmentation in abdominal magnetic resonance imaging with deep neural networks.

Segmentation of multiple organs-at-risk (OARs) is essential for magnetic resonance (MR)-only radiation therapy treatment planning and MR-guided adaptive radiotherapy of abdominal cancers. Current practice requires manual delineation that is labor-intensive, time-consuming, and prone to intra- and interobserver variations. We developed a deep learning (DL) technique for fully automated segmentation of multiple OARs on clinical abdominal MR images with high accuracy, reliability, and efficiency. We developed Automated deep Learning-based abdominal multiorgan segmentation (ALAMO) technique based on two-dimensional U-net and a densely connected network structure with tailored design in data augmentation and training procedures such as deep connection, auxiliary supervision, and multiview. The model takes in multislice MR images and generates the output of segmentation results. 3.0-Tesla T1 VIBE (Volumetric Interpolated Breath-hold Examination) images of 102 subjects were used in our study and split into 66 for training, 16 for validation, and 20 for testing. Ten OARs were studied, including the liver, spleen, pancreas, left/right kidneys, stomach, duodenum, small intestine, spinal cord, and vertebral bodies. An experienced radiologist manually labeled each OAR, followed by reediting, if necessary, by a senior radiologist, to create the ground-truth. The performance was measured using volume overlapping and surface distance. The ALAMO technique generated segmentation labels in good agreement with the manual results. Specifically, among the ten OARs, nine achieved high dice similarity coefficients (DSCs) in the range of 0.87-0.96, except for the duodenum with a DSC of 0.80. The inference completed within 1min for a three-dimensional volume of 320×288×180. Overall, the ALAMO model matched the state-of-the-art techniques in performance. The proposed ALAMO technique allows for fully automated abdominal MR segmentation with high accuracy and practical memory and computation time demands.

Assessment of biliary anatomy in potential living liver donors: Added value of gadoxetic acid–enhanced T1 MR Cholangiography (MRC) including utilization of controlled aliasing in parallel imaging results in higher acceleration (CAIPIRINHA) technique in comparison to T2W-MRC

ObjectivesTo assess the added value of gadoxetic-acid–enhanced T1-weighted magnetic resonance Cholangiography (T1W-MRC) including controlled aliasing in parallel imaging results in higher acceleration (CAIPIRINHA)-Volumetric Interpolated Breathhold (VIBE) technique compared to T2-weighted MR Cholangiography (T2W-MRC) in depicting biliary anatomy in potential living liver donors. MethodsEighty-five potential donors including 34 men with a mean age of 35.6 years (range, 18–55 years) and 51 women with a mean age of 36.7 years (range, 23–57 years), were enrolled in this ethics-approved retrospective study. Image quality for depiction of bile ducts was evaluated by two readers in consensus in 3 separate reading sessions: 1) T2W-MRC alone, 2) T1W-MRC alone (including CAIPI-VIBE and generalized autocalibrating partially parallel acquisitions (GRAPPA)-VIBE techniques, and 3) combined T1W/T2W-MRC. Accuracy of T2W-MRC, T1W-MRC, and combined T1W/T2W-MRC for the identification/classification of the biliary variants was calculated using intraoperative cholangiogram (IOC) as the reference standard. Image quality and reader diagnostic confidence provided by CAIPI-VIBE technique was compared with GRAPPA-VIBE technique. Datasets were compared using the Wilcoxon signed-rank test. ResultsImage quality for depiction of the bile ducts was significantly superior in the combined T1W/T2W-MRC group, when compared to each of T2W-MRC and T1W-MRC groups independently (P value = 0.001–0.034). The combination of CAIPI-VIBE and GRAPPA-VIBE was superior compared to each of the sequences individually. The accuracy of T2W-MRC and T1W-MRC was 93% and 91%, respectively. T1W-MRC depicted four biliary variants better than T2W-MRC. Two variants not well seen in T2W-MRC were clearly shown on T1W-MRC. ConclusionGadoxetic-acid–enhanced T1W-MRC and conventional T2W-MRC techniques are complementary for depiction of biliary variants in potential liver donors and the combination of the two improves the results. The combination of CAIPI-VIBE and GRAPPA-VIBE techniques appear to be complementary for optimal diagnostic yield of T1W-MRC.

Improved visualisation of hepatic metastases in gadoxetate disodium-enhanced MRI: Potential of contrast-optimised (phase-sensitive) inversion recovery imaging.

BackgroundDetection of metastases can have a significant impact on therapy. Nevertheless, even in gadoxetate disodium-enhanced MR scans, very small hepatic metastases may be difficult to see.PurposeTo investigate the potential of a contrast-optimised (phase-sensitive) inversion recovery MR sequence in gadoxetate disodium-enhanced scans for detection of hepatic metastases.Materials and methodsWith institutional review board approval and after written informed consent, 40 patients (18 male, 22 female) with suspected or known hepatic metastases were examined on a 1.5 T MR system. A T1-weighted gradient-echo volumetric-interpolated-breath-hold (VIBE) sequence was acquired as part of the standard imaging protocol 20 minutes after administration of gadoxetate disodium. Additionally, an IR sequence was acquired with an inversion time to suppress native signal from metastases. Overall image quality and delineation of lesions were assessed on VIBE as well as on magnitude-reconstructed (MAG) and phase-sensitive IR (PSIR) sequences. Lesion-to-liver contrast (LLC) was compared between VIBE and MAG images.ResultsOverall image quality was high in both VIBE and MAG IR sequences (VIBE 4.275; MAG 4.313), yet significantly lower in PSIR (4.038). Subjective delineation of lesions was higher on MAG and PSIR images compared to VIBE in all size groups with an overall statistically significant difference for VIBE vs. MAG vs. PSIR (p < .001) in the variance analysis. Mean LLC was 0.35±0.01 for VIBE sequences, and 0.73±0.01 for MAG.ConclusionContrast-optimised PSIR seems to improve imaging characteristics of hepatic metastases in gadoxetate disodium-enhanced scans compared to T1 gradient-echo VIBE sequences.

The nutcracker syndrome: The usefulness of different MRI sequences for diagnosis and follow-up

ObjectiveNutcracker Syndrome (NCS) is the extrinsic compression of the left renal vein by neighboring arterial, ligamentous, muscular, or osseous structures. Diagnosis is made by Doppler ultrasonography (US), multidetector computerized tomography (MDCT), magnetic resonance imaging (MRI), phlebography. The aim of the current study is to assess the value of MRI and compare the efficiency of different sequences in diagnosis and follow up of children with NCS. Material and methodsA total of 40 children (female/male ratio 3:1) with NCS were included in this prospective study. A standardized abdominal MRI protocol was used and T2-TRUFI (True Fast Imaging with Steady-State Free Precession), T2-HASTE (Half Fourier Acquisition with Single Shot Turbo Spin Echo), T1-VIBE (Volumetric Interpolated Breath Hold Examination), and out-of-phase (opposed-phase) T1 sequences were obtained. The sequences were compared according to anatomical depiction, measurability, and pulsation artifact. ResultsA four point-scale was used to assess subjective image quality and the results were listed as: 1 = poor, 2 = fair, 3 = good, and 4 = excellent. Both in total and for each individual criterion, the highest scores were obtained with T2-TRUFI (total mean 3.74 ± 0.45, anatomical depiction 3.9 ± 0.3, measurability 3.8 ± 0.4, aortic pulsation artifact 3.52 ± 0.55). ConclusionAlthough Doppler US is the gold standard technique in the diagnosis of NCS, MR imaging may be used as an additional modality, as it is superior to Doppler US in terms of anatomic depiction and a lower rate of imaging artifacts. Non-contrast MR imaging, particularly TRUFI sequence, may have an incremental value in the accurate diagnosis and follow-up of these patients.

Radiological diagnosis of drop metastases from paediatric brain tumours using combination of 2D and 3D MRI sequences

To evaluate spinal magnetic resonance imaging (MRI) examinations using a combination of two-dimensional (2D) and three-dimensional (3D) MRI sequences for diagnosis of drop metastases. Fifty-five paediatric patients with primary brain tumours wereevaluated for drop metastases at initial presentation using spinal MRI including sagittal 2D T1-weighted (W) contrast-enhanced (+C), axial 3D T1W+C volumetric interpolated breath-hold (VIBE), and sagittal 3D T2W SPACE (Sampling Perfection with Application optimised Contrasts using different flip angle Evolutions). The MRI false-negative rate was 4%, and cerebrospinal fluid (CSF) false-negative rate was 16% (p=0.07). The 3D T1W+C VIBE increased the number of drop metastases detected in 42% of patients. Drop metastases were more conspicuous in 25% of patients on 3D T2W SPACE. Spinal MRI examinations including 2D and 3D sequences demonstrate characteristics that may improve radiological diagnosis of drop metastases.

Comparison of CAIPIRINHA-VIBE, Radial-VIBE, and conventional VIBE sequences for dynamic contrast-enhanced (DCE) MRI: A validation study using a DCE-MRI phantom

ObjectiveTo validate radial acquisition of volumetric interpolated breath hold examination (Radial-VIBE) and the controlled aliasing in parallel imaging results in higher acceleration (CAIPIRINHA-VIBE) sequences for dynamic contrast-enhanced MRI (DCE-MRI) by comparing them to conventional VIBE sequence using a phantom. MethodsOn a DCE-MRI phantom containing various concentrations of NiCl2 solutions, six minutes of dynamic series and T1 mapping with variable flip angle methods were acquired using conventional VIBE, Radial-VIBE, and CAIPIRINHA-VIBE sequences on 3.0-T scanners. Signal stability and signal linearity were tested for dynamic series and the precision of R1 values were tested for T1 mapping series. The scans were repeatedly performed at two weeks and three months to test repeatability/reproducibility, assessed by within-subject coefficient of variation (WSCV). ResultsSignal stability over six minutes was excellent in all three sequences. Regarding the signal linearity, CAIPIRINHA-VIBE demonstrated the highest linear correlation (r=0.963), followed by conventional VIBE (r=0.959) and Radial-VIBE (r=0.953). Regarding the R1 precision, CAIPIRINHA-VIBE (r=0.985) was the most accurate, followed by conventional VIBE (r=0.861) and Radial-VIBE (r=0.442). CAIPIRINHA-VIBE showed excellent repeatability/reproducibility (WSCV, 1.79–6.71%) compared with Radial-VIBE (WSCV, 2.04–67.2%) and conventional VIBE (WSCV, 3.4–31.9%). ConclusionIn terms of signal stability, signal linearity, R1 precision, and repeatability/reproducibility, CAIPIRINHA-VIBE demonstrated outstanding performance for DCE-MRI compared with Radial-VIBE and conventional VIBE.

OP0050 Erosion Detection on the Si-Joints - A Comparison between X-Ray, Low Dose CT and MRI Including High Resolution Sequences

BackgroundThe value of magnetic resonance imaging (MRI) in the detection of erosions on the sacroiliac joints (SI-joints) is controversial. Structural changes on the other hand are getting more and more...

Clinical application of controlled aliasing in parallel imaging results in a higher acceleration (CAIPIRINHA)‐volumetric interpolated breathhold (VIBE) sequence for gadoxetic acid‐enhanced liver MR imaging

To determine whether a controlled aliasing in parallel imaging results in higher acceleration (CAIPIRINHA) technique can improve the image quality of three-dimensional (3D), T1-weighted gradient echo (T1w-GRE) imaging compared with the use of a standard, parallel acquisition technique (PAT). Sixty-four patients who underwent liver MR on a 3 Tesla (T) scanner, were included in this study. Twenty minutes after the injection of 0.025 mmole/kg of gadoxetic acid, 3D T1w-GRE imaging (volumetric interpolated breathhold examination [VIBE]) was acquired twice using a generalized autocalibrating partially parallel acquisition (384 × 250 matrix, acceleration factor [AF] of 2) and a CAIPIRINHA (384 × 380 matrix, AF of 4), respectively. Qualitative image analysis was performed for two image sets. CAIPIRINHA-VIBE showed better hepatic vessel clarity and lesion conspicuity than standard VIBE (P < 0.05). CAIPIRINHA-VIBE in the coronal plane also provided better results of motion artifact and liver edge sharpness than the standard VIBE (P < 0.05). Despite the more apparent PAT artifact on CAIPIRINHA-VIBE than on standard VIBE (P < 0.05), CAIPIRINHA-VIBE showed better overall image quality. The CAIPIRINHA-VIBE was able to provide a higher spatial resolution, T1-weighted imaging with better image quality compared with a standard VIBE.

Validity of gradient-echo three-dimensional delayed gadolinium-enhanced magnetic resonance imaging of hip joint cartilage: A histologically controlled study

ObjectiveTo validate gradient-echo three-dimensional (3D) delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) by means of histological analyses in the assessment of hip joint cartilage. Materials and methodsTwenty-one femoral head specimens collected from 21 patients (7 males, 14 females, mean age: 60.9±9.6 years; range: 37.6–77.3 years), who underwent total hip replacement for symptomatic hip joint osteoarthritis, underwent MRI and histological assessment. A region of 2cm2 at the weight-bearing area was marked with four pins to enable multi-planar MRI reformatting to be matched with histological sections. MRI was performed at 3T with a 3D double-echo steady-state (DESS) sequence for morphological cartilage assessment and 3D Volumetric Interpolated Breathhold Examination (VIBE) for T1Gd mapping. Histological sections were evaluated according to the Mankin score system. Total Mankin score, grade of toluidine staining (sensitive for glycosaminoglycan content) and a modified Mankin score classification system with four sub-groups of cartilage damage were correlated with MRI data. ResultsSpearman's rho correlation analyses revealed a statistically significant correlation between T1Gd mapping and histological analyses in all categories including total Mankin score (r=−0.658, p-value≤0.001), toluidine staining (r=−0.802, p-value<0.001) and modified Mankin score (r=−0.716, p-value<0.001). The correlation between morphological MRI and histological cartilage assessment was statistically significant but inferior to the biochemical cartilage MRI (r-values ranging from −0.411 to 0.525, p-values<0.001). ConclusionsGradient-echo dGEMRIC is reliable while offering the unique features of high image resolution and 3D biochemically sensitive MRI for the assessment of early cartilage degeneration.

MRI of the lumbar spine at 7 Tesla in healthy volunteers and a patient with congenital malformations

The aim of this study was to evaluate sequences that are established at lower magnetic field strengths for lumbar spine imaging at 7 Tesla (7T) MR imaging. The lumbar spine of five healthy volunteers and a patient with spina bifida and meningocele were evaluated at 7T. The examination included a T2-TSE (turbo spin echo), a 3D-DESS (double-echo steady-state sequence), a 3D-CISS (constructive interference in steady-state sequence), and a 3D-VIBE (volumetric interpolated breath hold examination) sequence. Imaging quality was evaluated by two raters on a three-level scale. The assessment included visualization of intraforaminal structures, the cauda equina, facet joints, and any abnormalities. Contrast ratios for intervertebral discs/vertebral bodies, vertebral bodies/cerebrospinal fluid (CSF) and CSF/spinal cord were calculated. The 3D-VIBE sequence provided best differentiation between intraforaminal structures. Visualization of the facet joints was reliable with VIBE, DESS, and CISS. Individual nerve roots of the cauda equina could only be delineated with the 3D-CISS sequence. CISS and DESS provided good contrast between vertebral bodies and intervertebral discs. Contrast between CSF and vertebral bodies was most pronounced for the T2-TSE sequence. Sufficient contrast between CSF and the spinal cord was only achieved with the T2-TSE sequence. VIBE and DESS sequences demonstrated best the bony malformations. Visualization of the meningocele was only possible with the 3D-CISS sequence. At 7T most structures of the lumbar spine were visualized with a combination of sequences. At present, imaging quality is not superior to 1.5T or 3T, precluding routine clinical use.

A paradoxical signal intensity increase in fatty livers using opposed-phase gradient echo imaging with fat-suppression pulses

With the increase in obese and overweight children, nonalcoholic fatty liver disease has become more prevalent in the pediatric population. Appreciating subtleties of magnetic resonance (MR) signal intensity behavior from fatty livers under different imaging conditions thus becomes important to pediatric radiologists. We report an initially confusing signal behavior-increased signal from fatty livers when fat-suppression pulses are applied in an opposed-phase gradient echo imaging sequence-and seek to explain the physical mechanisms for this paradoxical signal intensity behavior. Abdominal MR imaging at 3 T with a 3-D volumetric interpolated breath-hold (VIBE) sequence in the opposed-phase condition (TR/TE 3.3/1.3 ms) was performed in five obese boys (14+/-2 years of age, body mass index >95th percentile for age and sex) with spectroscopically confirmed fatty livers. Two VIBE acquisitions were performed, one with and one without the use of chemical shift selective (CHESS) pulse fat suppression. The ratios of fat-suppressed over non-fat-suppressed signal intensities were assessed in regions-of-interest (ROIs) in five tissues: subcutaneous fat, liver, vertebral marrow, muscle and spleen. The boys had spectroscopically estimated hepatic fat levels between 17% and 48%. CHESS pulse fat suppression decreased subcutaneous fat signals dramatically, by more than 85% within regions of optimal fat suppression. Fatty liver signals, in contrast, were elevated by an average of 87% with CHESS pulse fat suppression. Vertebral marrow signal was also significantly elevated with CHESS pulse fat suppression, while spleen and muscle signals demonstrated only small signal increases on the order of 10%. We demonstrated that CHESS pulse fat suppression actually increases the signal intensity from fatty livers in opposed-phase gradient echo imaging conditions. The increase can be attributed to suppression of one partner of the opposed-phase pair that normally contributes to the destructive interference between water and fat. The result is a paradoxical increase in signal from fatty liver that will depend on both fat content and the relative longitudinal relaxation times of fat methylene protons and water.

Dynamic contrast enhanced magnetic resonance imaging of bladder cancer and implications for biological image-adapted radiotherapy

Purpose. To assess the role of image parameters derived from dynamic contrast enhanced magnetic resonance imaging (DCEMRI) in bladder cancer staging, and to investigate the potential use of such parameter images in biological image-adapted radiotherapy (RT). Materials and methods. High-resolution volumetric interpolated breath-hold (VIBE) DCEMRI of 26 patients diagnosed with bladder cancer was performed. DCEMRI parameters derived from tumor and muscle contrast uptake curves were extracted and subjected to correlation analysis with tumor volume as well as clinical, pathological, histological and T2-weighted MR tumor stage. For parameters showing a significant correlation with tumor stage, 3D malignancy maps were generated. As an initial step towards delivery of biologically adapted intensity modulated radiotherapy (IMRT) it was hypothesized that the malignancy map could be used as a RT dose prescription map. Simulating IMRT delivery with multi-leaf collimators (MLCs), idealized dose distributions, constituted by dose cubes, were adapted to the prescription map. The size of the dose cubes were varied to mimic MLCs of varying leaf width. The difference between the adapted and prescribed dose distributions was quantified by the root mean square deviation (RMSD). Results. No significant relationships were found between tumor volume and extracted DCEMRI parameters. The normalized area between tumor and muscle contrast uptake curves (nABC) evaluated from 0–180 seconds (nABC180) and 0–480s (nABC480) correlated significantly with tumor stage (p=0.047 and p=0.035, respectively). Dose prescription maps for 10 patients were generated from the nABC480. The RMSD between the prescribed and adapted dose distribution decreased with decreasing size of the dose cubes. Large interpatient variations in the RMSD and in the dependence of the RMSD on different dose cube sizes were found. Conclusions. The nABC180 and nABC480 may provide added value in staging of bladder cancer. High-resolution IMRT is required for some patients for optimal adapted RT.

Magnetic Resonance Imaging of Lymphatic Vessels Without Image Subtraction

To assess the feasibility of a time-efficient, high-resolution magnetic resonance lymphangiography (HR MRL) protocol without image subtraction for the detection of lymphatic vessels in patients with primary and secondary lymphedema. Three consecutive patients with lymphedema of the lower extremities (2 primary bilateral, 1 secondary unilateral) underwent HR MRL without image subtraction. An amount of 9 mL of gadodiamide and 1 mL of mepivacaine hydrochloride 1% were subdivided into 5 portions and injected intracutaneously into the dorsal aspect of each foot outside the scanner before image acquisition. Magnetic resonance imaging was performed with a 1.5-T system equipped with high-performance gradients. For HR MRL, a 3-dimensional, spoiled gradient-echo sequence (Volumetric Interpolated Breath-hold Examination) was used. The extent and distribution of the lymphedema was evaluated using a heavily T2-weighted, 3-dimensional turbo-spin echo sequence. The HR MRL bilaterally detected the inguinal lymph nodes and the lymphatic vessels in the lower and upper leg in the 2 patients with primary lymphedema. In the patient with left-sided secondary lymphedema, the inguinal lymph nodes and the lymphatic vessels in the lower and upper leg were depicted on the right side. The diameter of the displayed lymphatic vessels varied between 1 and 5 mm. Three-dimensional, maximum-intensity projection images of different angles of view provided detailed outlining of the lymphatic vessels and differentiation from veins, which showed a lower signal intensity. The HR MRL without image subtraction is safe, technically feasible, and has the potential to become a diagnostic imaging tool in daily clinical practice because of its time efficiency.