Enhancing gadoxetic acid-enhanced liver MRI: a synergistic approach with deep learning CAIPIRINHA-VIBE and optimized fat suppression techniques.

OBJECTIVE: To investigate whether a deep learning (DL) controlled aliasing in parallel imaging results in higher acceleration (CAIPIRINHA)-volumetric interpolated breath-hold examination (VIBE) technique can improve image quality, lesion conspicuity, and lesion detection compared to a standard CAIPIRINHA-VIBE technique in gadoxetic acid-enhanced liver MRI. METHODS: This retrospective single-center study included 168 patients who underwent gadoxetic acid-enhanced liver MRI at 3 T using both standard CAIPIRINHA-VIBE and DL CAIPIRINHA-VIBE techniques on pre-contrast and hepatobiliary phase (HBP) images. Additionally, high-resolution (HR) DL CAIPIRINHA-VIBE was obtained with 1-mm slice thickness on the HBP. Three abdominal radiologists independently assessed the image quality and lesion conspicuity of pre-contrast and HBP images. Statistical analyses involved the Wilcoxon signed-rank test for image quality assessment and the generalized estimation equation for lesion conspicuity and detection evaluation. RESULTS: DL and HR-DL CAIPIRINHA-VIBE demonstrated significantly improved overall image quality and reduced artifacts on pre-contrast and HBP images compared to standard CAIPIRINHA-VIBE (p < 0.001), with a shorter acquisition time (DL vs standard, 11 s vs 17 s). However, the former presented a more synthetic appearance (both p < 0.05). HR-DL CAIPIRINHA-VIBE showed superior lesion conspicuity to standard and DL CAIPIRINHA-VIBE on HBP images (p < 0.001). Moreover, HR-DL CAIPIRINHA-VIBE exhibited a significantly higher detection rate of small (< 2 cm) solid focal liver lesions (FLLs) on HBP images compared to standard CAIPIRINHA-VIBE (92.5% vs 87.4%; odds ratio = 1.83; p = 0.036). CONCLUSION: DL and HR-DL CAIPIRINHA-VIBE achieved superior image quality compared to standard CAIPIRINHA-VIBE. Additionally, HR-DL CAIPIRINHA-VIBE improved the lesion conspicuity and detection of small solid FLLs. DL and HR-DL CAIPIRINHA-VIBE hold the potential clinical utility for gadoxetic acid-enhanced liver MRI. CLINICAL RELEVANCE STATEMENT: DL and HR-DL CAIPIRINHA-VIBE hold promise as potential alternatives to standard CAIPIRINHA-VIBE in routine clinical liver MRI, improving the image quality and lesion conspicuity, enhancing the detection of small (< 2 cm) solid focal liver lesions, and reducing the acquisition time. KEY POINTS: • DL and HR-DL CAIPIRINHA-VIBE demonstrated improved overall image quality and reduced artifacts on pre-contrast and HBP images compared to standard CAIPIRINHA-VIBE, in addition to a shorter acquisition time. • DL and HR-DL CAIPIRINHA-VIBE yielded a more synthetic appearance than standard CAIPIRINHA-VIBE. • HR-DL CAIPIRINHA-VIBE showed improved lesion conspicuity than standard CAIPIRINHA-VIBE on HBP images, with a higher detection of small (< 2 cm) solid focal liver lesions.

T1-VIBE and STIR MRI of lumbar pars interarticularis injuries in elite athletes: fracture characterisation and potential prognostic indicators.

OBJECTIVES: To assess how pars interarticularis fracture characteristics on T1-VIBE and STIR MRI relate to healing and identify anatomical parameters that may impact healing. MATERIALS AND METHODS: A retrospective review of an MRI series of lumbar pars interarticularis injuries in elite athletes over a 3-year period. Fracture configurations, signal intensities and anatomical parameters were recorded by two radiologists. Statistical analysis employed multilevel mixed-effects linear regressions, adjusted for repeated measures and baseline covariates. RESULTS: Forty-seven lumbar pars interarticularis injuries among 31 athletes were assessed. On final scans for each athlete, 15% (7/47) injuries had worsened, 23% (11/47) remained stable, 43% (20/47) partially healed and 19% (9/47) healed completely. Healing times varied, quickest was 49 days for a chronic fracture in a footballer. Bone marrow oedema signal was highest in worsened fractures, followed by improved, and lowest in stable fractures. As healing progressed, T1-VIBE signal at the fracture line decreased. Bone marrow oedema and fracture line signal peaked at 90-120 days before decreasing until 210-240 days. Fractures with smaller dimensions, more vertical orientation and a longer superior articular facet beneath were significantly associated with better healing (p < 0.05). CONCLUSION: Most diagnosed athletic pars interarticularis injuries improve. Normalising T1-VIBE signal at the fracture line is a novel measurable indicator of bony healing. Contrastingly, bone marrow oedema signal is higher in active fractures irrespective of healing or deterioration. Injuries initially perceived as worsening may be exhibiting the normal osteoclastic phase of healing. Better outcomes favour smaller, vertical fractures with a longer superior articular facet beneath.

Application of deep learning-based super-resolution to T1-weighted postcontrast gradient echo imaging of the chest.

OBJECTIVES: A deep learning-based super-resolution for postcontrast volume-interpolated breath-hold examination (VIBE) of the chest was investigated in this study. Aim was to improve image quality, noise, artifacts and diagnostic confidence without change of acquisition parameters. MATERIALS AND METHODS: Fifty patients who received VIBE postcontrast imaging of the chest at 1.5 T were included in this retrospective study. After acquisition of the standard VIBE (VIBES), a novel deep learning-based algorithm and a denoising algorithm were applied, resulting in enhanced images (VIBEDL). Two radiologists qualitatively evaluated both datasets independently, rating sharpness of soft tissue, vessels, bronchial structures, lymph nodes, artifacts, cardiac motion artifacts, noise levels and overall diagnostic confidence, using a Likert scale ranging from 1 to 4. In the presence of lung lesions, the largest lesion was rated regarding sharpness and diagnostic confidence using the same Likert scale as mentioned above. Additionally, the largest diameter of the lesion was measured. RESULTS: The sharpness of soft tissue, vessels, bronchial structures and lymph nodes as well as the diagnostic confidence, the extent of artifacts, the extent of cardiac motion artifacts and noise levels were rated superior in VIBEDL (all P < 0.001). There was no significant difference in the diameter or the localization of the largest lung lesion in VIBEDL compared to VIBES. Lesion sharpness as well as detectability was rated significantly better by both readers with VIBEDL (both P < 0.001). CONCLUSION: The application of a novel deep learning-based super-resolution approach in T1-weighted VIBE postcontrast imaging resulted in an improvement in image quality, noise levels and diagnostic confidence as well as in a shortened acquisition time.

Value for combination of T1WI star-VIBE with TWIST-VIBE dynamic contrast-enhanced MRI in distinguishing lung nodules. / T1WI star-VIBE增强结合TWIST-VIBE动态增强MRI对肺结节诊断的应用价值（英文）.

OBJECTIVES: With the increasing detection rate of lung nodules, the qualitative problem of lung nodules has become one of the key clinical issues. This study aims to evaluate the value of combining dynamic contrast-enhanced (DCE) MRI based on time-resolved imaging with interleaved stochastic trajectories-volume interpolated breath hold examination (TWIST-VIBE) with T1 weighted free-breathing star-volumetric interpolated breath hold examination (T1WI star-VIBE) in identifying benign and malignant lung nodules. METHODS: We retrospectively analyzed 79 adults with undetermined lung nodules before the operation. All nodules of patients included were classified into malignant nodules (n=58) and benign nodules (n=26) based on final diagnosis. The unenhanced T1WI-VIBE, the contrast-enhanced T1WI star-VIBE, and the DCE curve based on TWIST-VIBE were performed. The corresponding qualitative [wash-in time, wash-out time, time to peak (TTP), arrival time (AT), positive enhancement integral (PEI)] and quantitative parameters [volume transfer constant (Ktrans), interstitium-to-plasma rate constant (Kep), and fractional extracellular space volume (Ve)] were evaluated. Besides, the diagnostic efficacy (sensitivity and specificity) of enhanced CT and MRI were compared. RESULTS: There were significant differences in unenhanced T1WI-VIBE hypo-intensity, and type of A, B, C DCE curve type between benign and malignant lung nodules (all P<0.001). Pulmonary malignant nodules had a shorter wash-out time than benign nodules (P=0.001), and the differences of the remaining parameters were not statistically significant (all P>0.05). After T1WI star-VIBE contrast-enhanced MRI, the image quality was further improved. Compared with enhanced CT scan, the sensitivity (82.76% vs 80.50%) and the specificity (69.23% vs 57.10%) based on MRI were higher than that of CT (both P<0.001). CONCLUSIONS: T1WI star-VIBE and dynamic contrast-enhanced MRI based on TWIST-VIBE were helpful to improve the image resolution and provide more information for clinical differentiation between benign and malignant lung nodules.

Optimization of the image contrast for the developing fetal brain using 3D radial VIBE sequence in 3 T magnetic resonance imaging.

BACKGROUND: Faster and motion robust magnetic resonance imaging (MRI) sequences are desirable in fetal brain MRI. T1-weighted images are essential for evaluating fetal brain development. We optimized the radial volumetric interpolated breath-hold examination (VIBE) sequence for qualitative T1-weighted images of the fetal brain with improved image contrast and reduced motion sensitivity. MATERIALS AND METHODS: This was an institutional review board-approved prospective study. Thirty-five pregnant subjects underwent fetal brain scan at 3 Tesla MRI. T1-weighted images were acquired using a 3D radial VIBE sequence with flip angles of 6º, 9º, 12º, and 15º. T1-weighted images of Cartesian VIBE sequence were acquired in three of the subjects. Qualitative assessments including image quality and motion artifact severity were evaluated. The image contrast ratio between gray and white matter were measured. Interobserver reliability and intraobserver repeatability were assessed using intraclass correlation coefficient (ICC). RESULTS: Interobserver reliability and intraobserver repeatability universally revealed almost perfect agreement (ICC > 0.800). Significant differences in image quality were detected in basal ganglia (P = 0.023), central sulcus (P = 0.028), myelination (P = 0.007) and gray matter (P = 0.023) among radial VIBE with flip angles 6º, 9º, 12º, 15º. Image quality at the 9º flip angle in radial VIBE was generally better than flip angle of 15º. Radial VIBE sequence with 9º flip angle of gray matter was significantly different by gestational age (GA) before and after 28 weeks (P = 0.036). Quantified image contrast was significantly different among different flip angles, consistent with qualitative analysis of image quality. CONCLUSIONS: Three-dimensional radial VIBE with 9º flip angle provides optimal, stable T1-weighted images of the fetal brain. Fetal brain structure and development can be evaluated using high-quality images obtained using this angle. However, different scanners will achieve different TRs and so the FA should be re-optimized each time a new protocol is employed.

Effectiveness of Hemopatch® versus Surgicel® Original to control mild and moderate liver bleeding.

BACKGROUND: Adjunct hemostats can be of use in certain surgical settings. We compared the effectiveness of two hemostats, Hemopatch® and Surgicel® Original in controlling bleeding from liver lesions in an experimental model. METHODS: Control of grades 1 (mild) and 2 (moderate) bleeding (according to the Validated Intraoperative Bleeding [VIBe] SCALE) was assessed for 10 min after Hemopatch® (n = 198) or Surgicel® Original (n = 199) application on 397 liver surface lesions. The primary endpoint was hemostatic success (reaching VIBe SCALE grade 0 at 10 min). The secondary endpoint was time to hemostasis (time to reach and maintain grade 0). A generalized linear mixed model and an accelerated failure time model were used to assess the primary and secondary endpoints, respectively. RESULTS: The overall hemostatic success rate of Hemopatch® was statistically significantly superior to that of Surgicel® Original (83.8% versus 73.4%; p = 0.0036; odds ratio [OR] 2.38, 95% confidence interval [CI] 1.33-4.27) and time to hemostasis was reduced by 15.9% (p = 0.0032; 95% CI 0.749-0.944). Grade 2 bleeds treated with Hemopatch® had statistically significantly higher hemostatic success (71.7% versus 48.5%; p = 0.0007; OR 2.97, 95% CI 1.58-5.58) and shorter time to hemostasis (49.6% reduction, p = 3.6 × 10-8); differences for grade 1 bleeds (hemostatic success rate or time to hemostasis) were not statistically significant. CONCLUSIONS: Hemopatch® provided better control of VIBe SCALE bleeding compared to Surgicel® Original for Grade 2 bleeds in this porcine model, highlighting the importance of choosing a suitable hemostat to optimize control of bleeding during surgery.

Feasibility of 3D T1W sequences in contrast-material enhanced MR cisternography at 3T.

BACKGROUND: We investigated the diagnostic values and artifact severities of 3D-T1W sequences in the diagnosis of cerebrospinal fluid (CSF) leakage. METHODS: We retrospectively reviewed 3-tesla contrast-material enhanced MR cisternography exams of 22 patients with suspected CSF leakage in 4 years. The presence of the artifacts on 3D-T1W data was evaluated using a 4-point scale (0: none; 1: minimal; 2: moderate; 3: prominent). Agreements between CSF leakage results of the 3D-T1W sequences and consensus decisions were evaluated via kappa values. Artifact scores were analyzed by Fisher's exact test. RESULTS: The most compatible techniques with the consensus diagnoses were fat-saturated 3D-T1W-SPACE and 3D-T1W-VIBE sequences. The most artifact containing the 3D-T1W sequence was 3D-MPRAGE. DISCUSSION: 3D-SPACE and 3D-VIBE are more successful in evaluating CSF leakages compared to 3D-MPRAGE. 3D-SPACE has lower artifact scores compared to 3D-VIBE and 3D-MPRAGE sequences.

Cardiovascular magnetic resonance for the detection of descending thoracic aorta calcification in patients with end-stage renal disease.

BACKGROUND: Vascular calcification is an independent predictor of cardiovascular disease in patients with chronic kidney disease. Computed tomography (CT) is the gold-standard for detecting vascular calcification. Radial volumetric-interpolated breath-hold examination (radial-VIBE), a free-breathing gradient-echo cardiovascular magnetic resonance (CMR) sequence, has advantages over CT as it is ionising radiation-free. However, its capability in detecting thoracic aortic calcification (TAC) has not been investigated. This study aims to compare radial-VIBE to CT for the detection of TAC in the descending aorta of patients with end-stage renal disease (ESRD) using semi-automated methods, and to investigate the association between TAC and coronary artery calcification (CAC). METHODS: Paired cardiac CT and radial-VIBE CMR scans from ESRD patients participating in 2 prospective studies were obtained. Calcification volume was quantified using semi-automated methods in a 9 cm segment of the thoracic aorta. Correlation and agreement between TAC volume measured on CMR and CT were assessed with Spearman's correlation coefficient (ρ), linear regression, Bland-Altman plots and intraclass correlation coefficient (ICC). Association between CAC Agatston score and TAC volume determined by CT and CMR was measured with Spearman's correlation coefficient. RESULTS: Scans from 96 participants were analysed. Positive correlation was found between CMR and CT calcification volume [ρ = 0.61, 95% confidence interval (CI) 0.45-0.73]. ICC for consistency was 0.537 (95% CI 0.378-0.665). Bland-Altman plot revealed that compared to CT, CMR volumes were systematically higher at low calcification volume, and lower at high calcification volume. CT did not detect calcification in 41.7% of participants, while radial-VIBE CMR detected signal which the semi-quantitative algorithm reported as calcification in all of those individuals. Instances of suboptimal radial-VIBE CMR image quality were deemed to be the major contributors to the discrepancy. Correlations between CAC Agatston score and TAC volume measured by CT and CMR were ρ = 0.404 (95% CI 0.214-0.565) and ρ = 0.211 (95% CI 0.008-0.396), respectively. CONCLUSION: Radial-VIBE CMR can detect TAC with strong positive association to CT, albeit with the presence of proportional bias. Quantification of vascular calcification by radial-VIBE remains a promising area for future research, but improvements in image quality are necessary.

Imaging features of microwave-ablated lesions of the VX2 tumors in rabbit lungs on computed tomography and magnetic resonance images and their correlations with pathological examination.

PURPOSE: This study aimed to explore the accuracy of different imaging methods for lesion volume estimation pre- and post-microwave ablation (MWA) as compared with that of pathological examination. METHODS: We used the VX2 cell line to establish the VX2 lung tumor model in rabbits, followed by MWA of the tumor. The imaging features of the VX2 tumors were documented. The volume of the tumors and the ablated lesions were measured and compared across imaging methods, using the pathological examination as reference. RESULTS: Tumors were successfully developed in 11 rabbits (age, 13.91 ± 1.38 weeks; weight, 2.15 ± 0.56 kg). The mean volume of the tumors was 2.05 ± 1.88 cm3. CT showed the strongest correlation with the pathologic examination results (r = 0.998, p<.001). MWA created three-layered structures that were delineated on MRI. The mean volume of the post-ablation lesion was 10.39 ± 8.93 cm3, and the measurement of the post-ablation volume on 3D-VIBE-T1WI showed the strongest correlation with the pathologic examination results (r = 0.991, p<.001). CONCLUSION: Both CT and MRI are capable of depicting lung tumors. In terms of post-ablation evaluation, MR images could provide more versatile information. The 3D-VIBE-T1WI sequence provides more precise lesion volume evaluation after ablation compared with other methods.

Optimizing MR imaging for intraoperative image guidance in sellar pathologies.

PURPOSE: With the advancement of extended endonasal approaches, the ability to surgically reach parasellar tumor extensions increase. The aim of the study was to propose an optimized imaging protocol for surgical guidance in the cavernous sinus (CS) for proper visualization structures at risk. METHODS: Prospective case control analysis of 20 consecutive pituitary adenoma patients scheduled for endoscopic transnasal surgery. Assessment of the capability of three different MRI sequences (MPRAGE, VIBE, CISS) by 4 investigators to correctly visualize sellar and parasellar structures. Invasiveness and position of the normal pituitary gland were compared with the intraoperative findings. RESULTS: The consensus between the 4 examiners to achieve the same results for all modalities was 40% for MPRAGE, 70% for VIBE and 60% for CISS sequences (p = 0.155). A consensus of Knosp Grade per patient was 80% for MPRAGE, 100% for VIBE and 90% for CISS (overall kappa 0.60). A higher Knosp Grade was found in MPRAGE sequences compared to the other sequences. Intraoperative status of invasiveness was correctly identified in 12/20 (60%) with MPRAGE, 19/20 (95%) with VIBE and 11/20 (55%) with CISS sequences. The position of the normal pituitary gland was most frequent evaluable in 15/20 (75%) and correctly identified in 12/15 (80%) cases. CONCLUSION: Our data showed that VIBE sequences obtain the highest degree of consensus with intraoperative findings of invasiveness and position of the normal pituitary gland. VIBE sequences, due to their high spatial resolution and at the same time fast image acquisition could provide improved imaging for neuronavigation.

Feasibility of pulmonary MRI for nodule detection in comparison to computed tomography.

BACKGROUND: To assess the feasibility of various magnetic resonance imaging (MRI) sequences for the detection of pulmonary nodules by comparing the detection rate of computed tomography (CT). METHODS: Forty-two patients with pulmonary nodules detected by multi-slice CT (MSCT) were prospectively enrolled in the present study between November 2016 and February 2017. Chest MRI was acquired within 24 h of CT. The MRI protocol included free-breathing radial VIBE (r-VIBE) and a conventional breathhold T1-weighted VIBE (C-VIBE) were analyzed by two independent radiologists. Both detection and morphology results of each MRI image were recorded. Subjective image evaluation in terms of overall nodule morphology on the MRI images was carried out using the 4-point scoring criteria. The MRI results were compared with those from CT, with the results of MSCT serving as the reference standard. RESULTS: Two hundred and fifty-eight solid pulmonary nodules in 42 patients were detected by CT. The r-VIBE correctly detected 94% of the pulmonary nodules as compared with CT. The detection rate increased to 100% for lesions ≥6 mm. The C-VIBE had a lower overall detection rate (64.3%) of pulmonary nodules. The difference in the subjective image evaluation scores between the two sequences was statistically significant (p < 0.001). CONCLUSION: Significantly increased detection rates were obtained with free-breathing r-VIBE as compared with C-VIBE for the detection of pulmonary nodules and also provided more information when evaluating the nodules as compared with C-VIBE.

[Examination of Gd-EOB-DTPA Liver Dynamic Contrast-enhanced MRI Using Radial VIBE with k-space Weighted Image Contrast Method].

Dynamic contrast-enhanced magnetic imaging (DCE-MRI) is a useful method for detection and diagnosis of liver lesions. However, DCE-MRI using Gd-EOB-DTPA has some problems with arterial phase images. Radial volumetric imaging breath-holding examination (r-VIBE) with k-space weighted image contrast reconstruction (KWIC), which is a modification of Cartesian VIBE (c-VIBE), is a new 3D-gradient echo sequence with a number of advantages compared with c-VIBE, including lower motion sensitivity. This study was performed to evaluate image contrast, blurring, and temporal phase division effects of r-VIBE in comparison with c-VIBE. Image contrast using diluted Gd-EOB-DTPA aqueous solution showed no significant difference between r-VIBE and c-VIBE. Imaging was performed with r-VIBE and c-VIBE during injection of a Gd-EOB-DTPA solution into a serpentine tube. r-VIBE showed a smaller half-width of the signal intensity profile of the tube and less image artifacts by blurring when compared to c-VIBE. The arrival times and durations of the maximum signal strengths of r-VIBE and c-VIBE images during injection of Gd-EOB-DTPA solution into the tube were almost identical. r-VIBE improved the temporal resolution without degradation of liver DCE-MRI using Gd-EOB-DTPA.

Comparison between free-breathing radial VIBE on 3-T MRI and endoscopic ultrasound for preoperative T staging of resectable oesophageal cancer, with histopathological correlation.

OBJECTIVES: To compare the T staging of resectable oesophageal cancer (OC) using radial VIBE (r-VIBE) and endoscopic ultrasound (EUS) with pathological confirmation of the T stage. METHODS: Forty-three patients with endoscopically proven OC and indeterminate T1/T2/T3/T4a stage by computed tomography (CT) and EUS were imaged on a 3-T magnetic resonance imaging (MRI) scanner. T stage was scored on MRI and EUS by two independent radiologists and one endoscopist, respectively, and compared with postoperative pathological findings. T staging agreement between r-VIBE and EUS with postoperative pathological T staging was analysed by a kappa test. RESULTS: EUS and pathological T staging showed agreement of 69.8% (30/43). Radial VIBE and pathological T staging agreement was 86.0% (37/43) and 90.7% (39/43) for readers 1 and 2, respectively. High accuracy for T1/T2 stage was obtained for both r-VIBE readers (90.5% and 100% for reader 1 and reader 2, respectively) and EUS reader (100%). For T3/T4, r-VIBE showed accuracy of 81.8% and 90.9% for reader 1 and reader 2, respectively, while for EUS, accuracy was only 68.2% compared with pathological T staging. CONCLUSIONS: Contrast-enhanced r-VIBE is comparable to EUS in T staging of resectable OC with stage of T1/T2, and is superior to EUS in staging of T3/T4 lesions. KEY POINTS: • Radial VIBE may be useful in preoperative T staging of OC • Accuracy of staging on r-VIBE is higher in T1/2 than in T3/4 • Accuracy of EUS was 100% and 68.2% for T1/T2 and T3/T4 stage • Inter-reader agreement of T staging for r-VIBE was good.

Feasibility of free-breathing dynamic contrast-enhanced MRI of gastric cancer using a golden-angle radial stack-of-stars VIBE sequence: comparison with the conventional contrast-enhanced breath-hold 3D VIBE sequence.

OBJECTIVES: To investigate the feasibility and diagnostic value of free-breathing, radial, stack-of-stars three-dimensional (3D) gradient echo (GRE) sequence ("golden angle") on dynamic contrast-enhanced (DCE) MRI of gastric cancer. METHODS: Forty-three gastric cancer patients were divided into cooperative and uncooperative groups. Respiratory fluctuation was observed using an abdominal respiratory gating sensor. Those who breath-held for more than 15 s were placed in the cooperative group and the remainder in the uncooperative group. The 3-T MRI scanning protocol included 3D GRE and conventional breath-hold VIBE (volume-interpolated breath-hold examination) sequences, comparing images quantitatively and qualitatively. DCE-MRI parameters from VIBE images of normal gastric wall and malignant lesions were compared. RESULTS: For uncooperative patients, 3D GRE scored higher qualitatively, and had higher SNRs (signal-to-noise ratios) and CNRs (contrast-to-noise ratios) than conventional VIBE quantitatively. Though 3D GRE images scored lower in qualitative parameters compared with conventional VIBE for cooperative patients, it provided images with fewer artefacts. DCE parameters differed significantly between normal gastric wall and lesions, with higher Ve (extracellular volume) and lower Kep (reflux constant) in gastric cancer. CONCLUSIONS: The free-breathing, golden-angle, radial stack-of-stars 3D GRE technique is feasible for DCE-MRI of gastric cancer. Dynamic enhanced images can be used for quantitative analysis of this malignancy. KEY POINTS: • Golden-angle radial stack-of-stars VIBE aids gastric cancer MRI diagnosis. • The 3D GRE technique is suitable for patients unable to suspend respiration. • Method scored higher in the qualitative evaluation for uncooperative patients. • The technique produced images with fewer artefacts than conventional VIBE sequence. • Dynamic enhanced images can be used for quantitative analysis of gastric cancer.

Three-Dimensional Radial VIBE Sequence for Contrast-Enhanced Brain Imaging: An Alternative for Reducing Motion Artifacts in Restless Children.

OBJECTIVE: The purpose of this study was to evaluate the usefulness of radially sampled 3D fat-suppressed T1-weighted gradient-echo sequences (radial volumetric interpolated breath-hold examination [radial VIBE]) for contrast-enhanced brain MRI of children through comparison with a magnetization-prepared rapid-acquisition gradient-echo (MP-RAGE) sequence. MATERIALS AND METHODS: Sixty-five consecutive contrast-enhanced brain MRI examinations performed with axial MP-RAGE and radial VIBE sequences were included. For quantitative analysis, coefficients of variation of gray matter and white matter and CSF and relative contrast between tissue types (gray matter and white matter, gray matter and CSF, and white matter and CSF) for each sequence were calculated. For qualitative assessment, motion, pulsation artifacts, overall image quality, and lesion conspicuity were retrospectively scored on a 5-point scale. Quantitative and qualitative subgroup analyses were performed for patients with serious motion artifacts. RESULTS: Images obtained with the radial VIBE sequence had fewer motion and pulsation artifacts than those obtained with the MP-RAGE sequence (MP-RAGE vs radial VIBE motion score, 3.57 ± 1.00 vs 4.52 ± 0.51; pulsation score, 3.57 ± 0.60 vs 4.91 ± 0.21; all p < 0.001). Among 25 images with serious motion artifacts, radial VIBE images had significantly higher scores for all qualitative parameters, including overall image quality, than did MP-RAGE images (overall image quality for MP-RAGE vs radial VIBE, 2.63 ± 0.82 vs 3.42 ± 0.55, p < 0.001). CONCLUSION: The study showed that a radial fat-suppressed T1-weighted gradient-echo sequence is a viable alternative to conventional cartesian acquisition for contrast-enhanced brain imaging of restless children.

Feasibility of self-gated isotropic radial late-phase MR imaging of the liver.

OBJECTIVE: To evaluate feasibility of a 3D-isotropic self-gated radial volumetric interpolated breath-hold examination (VIBE) for late-phase MRI of the liver. MATERIAL AND METHODS: 70 patients were included and underwent liver MRI at 1.5 T. Depending on the diagnosis, either Gd-EOB-DTPA (35 patients) or gadobutrol (35 patients) were administered. During late (gadobutrol) or hepatocyte-specific phase (Gd-EOB-DTPA), a radial prototype sequence was acquired and reconstructed using (1) self-gating with 40 % acceptance (rVIBE40); (2) with 100 % acceptance of the data (rVIBE100) and compared to Cartesian VIBE (cVIBE). Images were assessed qualitatively (image quality, lesion conspicuity, artefacts; 5-point Likert-scale: 5 = excellent; two independent readers) and quantitatively (coefficient-of-variation (CV); contrast-ratio) in axial and coronal reformations. RESULTS: In eight cases only rVIBE provided diagnostic image quality. Image quality of rVIBE40 was rated significantly superior (p < 0.05) in Gd-EOB-DTPA-enhanced and coronal reformatted examinations as compared to cVIBE. Lesion conspicuity was significantly improved (p < 0.05) in coronal reformatted Gd-EOB-DTPA-enhanced rVIBE40 in comparison to cVIBE. CV was higher in rVIBE40 as compared to rVIBE100/cVIBE (p < 0.01). Gadobutrol-enhanced rVIBE40 and cVIBE showed higher contrast-ratios than rVIBE100 (p < 0.001), whereas no differences were found in Gd-EOB-DTPA-enhanced examinations. CONCLUSION: Self-gated 3D-isotropic rVIBE provides significantly superior image quality compared to cVIBE, especially in multiplanar reformatted and Gd-EOB-DTPA-enhanced examinations. KEY POINTS: • Radial VIBE acquisition reduces motion artefacts. • Gd-EOB-DTPA-enhanced scans provide improved image quality. • Non-diagnostic liver MRI examinations may be reduced by radial k-spaces sampling.

Advanced MRI Techniques of the Shoulder Joint: Current Applications in Clinical Practice.

OBJECTIVE: We are fortunate to live in a time when real advances in medicine are happening at an increasingly rapid pace. This is especially true in the field of radiology, and keeping abreast of these advances is one of the main challenges of clinical practice. Traditionally, cutting edge techniques in our field have been researched and validated at major academic medical centers before slowly making their way into the armamentarium of routine clinical practice. However, the improved ability to communicate and disseminate information in our modern age has facilitated more rapid implementation of new techniques to allow us to better serve our patients. CONCLUSION: As such, this article aims to review the current standards for MRI of the shoulder used in routine practice. Furthermore, we will discuss some of the most recent advances in shoulder MRI, with particular emphasis on the applicability of an additional axial 3D T1-weighted FLASH sequence with Dixon-based water-fat separation in routine clinical practice that can be useful in characterizing several commonly encountered pathologic processes of the shoulder joint.

Rapid Cartesian versus radial acquisition: comparison of two sequences for hepatobiliary phase MRI at 3 tesla in patients with impaired breath-hold capabilities.

BACKGROUND: Hepatocyte-specific gadolinium based contrast agents (HSCA) provide substantial information for the classification of liver lesions in magnetic resonance imaging (MRI). However, breathing artifacts which reduce image quality and diagnostic confidence of hepatobiliary phase acquisitions are regularly observed in clinical routine. The aim of this study was to evaluate two approaches to reduce breathing artifacts for hepatobiliary phase imaging. METHODS: Twenty minutes after administration of a HSCA (gadoxetic acid), a T1-weighted VIBE sequence with radial k-space sampling (radialVIBE, 180 s acquisition time in free breathing) and a highly accelerated Cartesian VIBE with Dixon fat separation (CD-VIBE, CAIPIRINHA acceleration with r = 2 × 2, breath-hold 8-10 s) were acquired in 35 patients (12 female, 57 ± 13 years), who showed breath-holding difficulties in early phases of the examinations. Image quality (image sharpness, noise, artifacts, homogeneity of fat saturation, bile duct delineation and overall image quality) as well as conspicuity and liver-to-lesion signal intensity (SI) ratios of focal liver lesions were assessed for both radial- and CD-VIBE. RESULTS: Overall image quality was rated good to excellent for both sequences, while CD-VIBE was preferred in most cases. Though radialVIBE received better results regarding image noise and artifacts, both sequences were rated equally regarding bile duct delineation and sharpness. Focal liver lesion (n = 42) conspicuity was rated significantly better and SI-ratios were significantly higher on CD-VIBE (2.45 ± 1.44 vs. 1.61 ± 0.70 in radialVIBE, p = 0.0001). In three patients, CD-VIBE was rated non-diagnostic due to severe breathing artifacts, while radialVIBE was diagnostic in those patients. CONCLUSION: Both highly accelerated Cartesian as well as radial acquisition techniques provide good to excellent image quality in hepatobiliary phase MRI. In comparison, CD-VIBE offered better overall image quality and liver lesion conspicuity. However, radialVIBE was a valuable alternative in patients unable to sustain even short breath-hold intervals. Further studies including lager patient cohorts are desirable to allow a transfer of these results to a general patient population.

Breath-hold MR measurements of fat fraction, T1 , and T2 * of water and fat in vertebral bone marrow.

PURPOSE: To assess the feasibility of measuring the fat fraction, T1 and T2 * relaxation times of water and fat signals in vertebral bone marrow using breath-hold magnetic resonance imaging (MRI) gradient echo images of the spine. MATERIALS AND METHODS: MRI experiments were performed at 1.5T on eight healthy volunteers (35.1 ± 15.7 years, five men and three women) using two sagittal four-echo 3D gradient echo volumetric interpolated breath-hold examination (VIBE Dixon) sequences acquired at two different flip angles (5° and 15°). The water/fat decomposition was performed in the vertebral bodies of L1 to L5 by fitting the signal to a function that depends on the echo time and the flip angle to calculate the fat fraction (FF) and T1 and T2 * relaxation times of water and fat signals. Repeatability was assessed by scanning one volunteer six times. RESULTS: The mean fat fraction over L1 to L5 was 33 ± 8%. The mean T1 and T2 * of water and fat signals were respectively T1w = 701 ± 151 msec, T2 *w = 13.7 ± 2.9 msec, T1f = 334 ± 113 msec, and T2 *f = 11.4 ± 2.7 msec. When considering each vertebra separately, the fat fraction increased from L1 to L5 and the T1w decreased from L1 to L5. The mean coefficients of variation obtained from the repeatability study were 8% (FF), 11% (T1w ), 17% (T1f ), 8% (T2 *w ), and 27% (T2 *f ). CONCLUSION: The method introduced in the current study allows for the measurement of the fat fraction and water and fat relaxation times, with a total acquisition time of less than 40 seconds. J. Magn. Reson. Imaging 2016;44:549-555.

Advantages of radial volumetric breath-hold examination (VIBE) with k-space weighted image contrast reconstruction (KWIC) over Cartesian VIBE in liver imaging of volunteers simulating inadequate or no breath-holding ability.

OBJECTIVES: To investigate the superiority of radial volumetric breath-hold examination (r-VIBE) with k-space weighted image contrast reconstruction (KWIC) over Cartesian VIBE (c-VIBE) for reducing motion artefacts. METHODS: We acquired r-VIBE-KWIC and c-VIBE images in 10 healthy volunteers. Each acquisition lasted 24 seconds. The volunteers held their breath for decreasing lengths of time during the acquisitions, from 24 to 0 seconds (protocols A-E). Magnetic resonance images at the level of the right portal vein and confluence of hepatic veins were assessed by two readers using a five-point scale with a higher number indicating a better study. RESULTS: The mean scores for the complete r-VIBE-KWIC series (r-VIBEfull) and first r-VIBE-KWIC series (r-VIBE1) were not significantly lower than those for c-VIBE in any protocols. The mean scores for c-VIBE were lower than those for r-VIBEfull and r-VIBE1 in protocols C and D. The mean score for c-VIBE was lower than that for r-VIBEfull in protocol E. The mean score for the eighth r-VIBE-KWIC series (r-VIBE8) was lower than that for c-VIBE only in protocol B. CONCLUSION: r-VIBE-KWIC minimised artefacts relative to c-VIBE at any slice location. The r-VIBE-KWIC's sub-frame images during the breath-holding period were hardly affected by another failed breath-holding period. KEY POINTS: • A two-reader study revealed r-VIBE-KWIC's advantages over c-VIBE • The image quality of r-VIBE-KWIC's sub-frame images was maintained during breath holding • Full-frame r-VIBE-KWIC images minimized motion artefacts caused by breathing • A complete breath holding over half the acquisition time is recommended for c-VIBE • c-VIBE was susceptible to respiratory motion especially in the subphrenic region.