T2-weighted Spin-echo Sequences Research Articles

Comparing lesion detection of infratentorial multiple sclerosis lesions between T2-weighted spin-echo, 2D-FLAIR, and 3D-FLAIR sequences

PurposeInfratentorial lesions in patients with multiple sclerosis are associated with long-term disability. Two-dimensional fluid-attenuated inversion recovery demonstrates poor infratentorial lesion detection when compared to T2-weighted spin echo. Evidence of improved detection with 3D fluid-attenuated inversion recovery has been conflicting. This study compares the infratentorial lesion detection performance, observer performance, and signal and contrast properties between T2-weighted spin echo, 2D, and 3D fluid-attenuated inversion recovery. MethodsTwo board-certified radiologists independently reviewed and counted infratentorial lesions from 85 brain MRIs in patients with clinically definite multiple sclerosis and concurrent 3D, 2D fluid-attenuated inversion recovery, and T2-weighted spin echo sequences. Contrast-to-noise and signal-to-noise ratios were measured for 25 MRIs. Wilcoxon signed-rank test was used for pairwise comparisons of the combined average infratentorial lesion count, contrast-to-noise, and signal-to-noise ratios, and was adjusted for three pairwise comparisons using Bonferroni correction. A corrected p value < 0.05 was considered statistically significant. ResultsThe number of lesions on 3D fluid-attenuated inversion recovery was significantly higher than those on 2D (p < 0.001) and T2-weighted spin echo (p < 0.001). Results of contrast-to-noise and signal-to-noise ratios were overall mixed and predominantly not concordant with lesion count findings, with T2-weighted spin echo demonstrating the highest signal-to-noise ratios and contrast-to-noise ratio of lesion compared with white matter but the lowest contrast-to-noise ratio of lesion compared with gray matter. ConclusionThe 3D fluid-attenuated inversion recovery sequence addresses the disadvantage of poor infratentorial lesion detection on 2D, while still maintaining the advantage over T2-weighted spin echo in the detection of lesions adjacent to the cerebrospinal fluid.

Radiomics of liver MRI predict metastases in mice

BackgroundThe purpose of this study was to investigate whether any texture features show a correlation with intrahepatic tumor growth before the metastasis is visible to the human eye.MethodsEight male C57BL6 mice (age 8–10 weeks) were injected intraportally with syngeneic MC-38 colon cancer cells and two mice were injected with phosphate-buffered saline (sham controls). Small animal magnetic resonance imaging (MRI) at 4.7 T was performed at baseline and days 4, 8, 12, 16, and 20 after injection applying a T2-weighted spin-echo sequence. Texture analysis was performed on the images yielding 32 texture features derived from histogram, gray-level co-occurrence matrix, gray-level run-length matrix, and gray-level size-zone matrix. The features were examined with a linear regression model/Pearson correlation test and hierarchical cluster analysis. From each cluster, the feature with the lowest variance was selected.ResultsTumors were visible on MRI after 20 days. Eighteen features from histogram and the gray-level-matrices exhibited statistically significant correlations before day 20 in the experiment group, but not in the control animals. Cluster analysis revealed three distinct clusters of independent features. The features with the lowest variance were Energy, Short Run Emphasis, and Gray Level Non-Uniformity.ConclusionsTexture features may quantitatively detect liver metastases before they become visually detectable by the radiologist.

Applicability of T1-weighted MRI in the assessment of forensic age based on the epiphyseal closure of the humeral head.

This work investigates the value of magnetic resonance imaging analysis of proximal epiphyseal fusion in research examining the growth and development of the humerus and its potential utility in establishing forensic age estimation. In this study, 428 proximal humeral epiphyses (patient age, 12-30years) were evaluated with T1-weighted turbo spin echo (T1 TSE) sequences in coronal oblique orientation on shoulder MRI images. A scoring system was created following a combination of the Schmeling and Kellinghaus methods. Spearman's rank correlation analysis revealed a significant positive relationship between age and ossification stage of the proximal humeral epiphysis (all subjects: rho = 0.664, p< 0.001; males: 0.631, p< 0.001; females: rho = 0.651, p< 0.001). The intra- and inter-observer reliability assessed using Cohen's kappa statistic was κ = 0.898 and κ = 0.828, respectively. The earliest age of epiphysis closure was 17years for females and 18years for males. MRI of the proximal humeral epiphysis can be considered advantageous for forensic age estimation of living individuals in a variety of situations, ranging from monitoring public health to estimating the age of illegal immigrants/asylum seekers, minors engaged in criminal activities, and illegal participants in competitive sports, without the danger of radiation exposure.

Radiographic Study of Lumbar Sympathetic Trunk in Oblique Lateral Interbody Fusion Surgery

Oblique lateral interbody fusion (OLIF) surgery provides a convenient and minimal access to the lesion disc with few complications; however, the left lumbar sympathetic trunk (LST) lies in the surgical field with a certain incidence of injury. The aim of this study was to describe the anatomic structures of the left LST at risk for injury during OLIF at different lumbar segment levels based on radiologic evaluations. Forty-four healthy young people (22 men and 22 women) were recruited, and routine lumbar magnetic resonance radiograph was performed. The LST, abdominal aorta (AA), and psoas muscle (PM) were observed, and all parameters were acquired using axial T2-weighted turbo spin echo sequence images. Independent-samples t test, 1-way analysis of variance test, and Least significant difference test were used to explore the LST's tract and the anatomic relationship with the adjacent anatomic landmarks at different levels. The distance from the left lateral border of the AA to the anterior medial border of the left PM was significantly narrowing from the L2-3 to L4-5 segment levels (13.72 ± 3.00, 11.78 ± 2.69, and 9.18 ± 3.43 mm). The distance from the left lateral border of the AA to the left LST was also significantly decreased from the L2-3 to L4-5 segment levels (11.14 ± 2.89, 9.36 ± 2.79, and 6.63 ± 2.94 mm). However, the distance from the leading edge of the left PM to the left LST had no statistical differences among all adjacent segment levels (2.96 ± 0.62, 2.83 ± 0.62, and 3.07 ± 0.86 mm). The location of the left LST is more backward and lateral at level L2-3, whereas it is inside front at levels L3-4 and L4-5. The practical risk of LST injury in different segment levels varied with specific anatomic conditions. The segment level L2-3 could provide a safer surgical space for OLIF, and the risk of the left LST injury might be greater during OLIF at level L4-5.

Circumferential Wall Enhancement on Magnetic Resonance Imaging is Useful to Identify Rupture Site in Patients with Multiple Cerebral Aneurysms.

Identification of rupture sites in patients with multiple intracranial aneurysms is largely based on aneurysm size, location, and shape. Finding circumferential enhancement along the aneurysm wall (CEAW) on magnetic resonance (MR) vessel wall imaging was recently shown to be indicative of ruptured aneurysm. To investigate the hypothesis that a higher degree of CEAW would identify the site of rupture in patients with multiple aneurysms. We prospectively performed quantitative analysis of CEAW in consecutive patients with both aneurysmal subarachnoid hemorrhage and multiple aneurysms (26 patients with a total of 62 aneurysms), using MR vessel wall imaging. Three-dimensional T1-weighted fast spin-echo sequences were obtained before and after injection of contrast media, and the wall enhancement index (WEI) was calculated. Aneurysm characteristics (size, location, irregular shape, aspect ratio [neck-to-dome length/neck width], and WEI) were compared between ruptured and unruptured aneurysms. Odds ratios with 95% confidence intervals for ruptures were calculated with conditional univariable logistic regression analysis. Analyses were repeated after adjustment for aneurysm size. Large aneurysm size, high aspect ratio, WEI (above the median values), and irregular shape were significantly associated with aneurysm rupture. After adjustment for aneurysm size, WEI (adjusted odds ratio: 8.8; 95% confidence interval, 1.1-72.6) as well as irregular shape and aspect ratio showed a strong association with rupture. CEAW is associated with rupture of intracranial aneurysm independent of aneurysm size and patient characteristics. Contrast-enhanced MR vessel wall imaging helps to identify the site of rupture in patients with multiple aneurysms.

3D Ultrashort TE MRI for Evaluation of Cartilaginous Endplate of Cervical Disk In Vivo: Feasibility and Correlation With Disk Degeneration in T2-Weighted Spin-Echo Sequence.

The purpose of this study was to evaluate the feasibility of 3D ultrashort TE (UTE) MRI in depicting the cartilaginous endplate (CEP) and its abnormalities and to investigate the association between CEP abnormalities and disk degeneration on T2-weighted spin-echo (SE) MR images in cervical disks in vivo. Eight healthy volunteers and 70 patients were examined using 3-T MRI with the 3D UTE cones trajectory technique (TR/TE, 16.1/0.032, 6.6). In the volunteer study, quantitative and qualitative assessments of CEP depiction were conducted for the 3D UTE and T2-weighted SE imaging. In the patient study, CEP abnormalities were analyzed. Intersequence agreement between the images obtained with the first-echo 3D UTE sequence and the images created by subtracting the second-echo from the first-echo 3D UTE sequence (subtracted 3D UTE) and the intraobserver and interobserver agreements for 3D UTE overall were also tested. The CEP abnormalities on the 3D UTE images correlated with the Miyazaki grading of the T2-weighted SE images. In the volunteer study, the CEP was well visualized on 3D UTE images but not on T2-weighted SE images (p < 0.001). In the patient study, for evaluation of CEP abnormalities, intersequence agreements were substantial to almost perfect, intraobserver agreements were substantial to almost perfect, and interobserver agreements were moderate to substantial (p < 0.001). All of the CEP abnormalities correlated with the Miyazaki grade with statistical significance (p < 0.001). Three-dimensional UTE MRI feasibly depicts the CEP and CEP abnormalities, which may be associated with the severity of disk degeneration on T2-weighted SE MRI.

Magnetic resonance imaging (MRI) of the renal sinus.

This article presents methods to improve MR imaging approach of disorders of the renal sinus which are relatively uncommon and can be technically challenging. Multi-planar Single-shot T2-weighted (T2W) Fast Spin-Echo sequences are recommended to optimally assess anatomic relations of disease. Multi-planar 3D-T1W Gradient Recalled Echo imaging before and after Gadolinium administration depicts the presence and type of enhancement and relation to arterial, venous, and collecting system structures. To improve urographic phase MRI, concentrated Gadolinium in the collecting systems should be diluted. Diffusion-Weighted Imaging (DWI) should be performed before Gadolinium administration to minimize T2* effects. Renal sinus cysts are common but can occasionally be confused for dilated collecting system or calyceal diverticula, with the latter communicating with the collecting system and filling on urographic phase imaging. Vascular lesions (e.g., aneurysm, fistulas) may mimic cystic (or solid) lesions on non-enhanced MRI but can be suspected by noting similar signal intensity to the blood pool and diagnosis can be confirmed with MR angiogram/venogram. Multilocular cystic nephroma commonly extends to the renal sinus, however, to date are indistinguishable from cystic renal cell carcinoma (RCC). Solid hilar tumors are most commonly RCC and urothelial cell carcinoma (UCC). Hilar RCC are heterogeneous, hypervascular with epicenter in the renal cortex compared to UCC which are centered in the collecting system, homogeneously hypovascular, and show profound restricted diffusion. Diagnosis of renal sinus invasion in RCC is critically important as it is the most common imaging cause of pre-operative under-staging of disease. Fat is a normal component of the renal sinus; however, amount of sinus fat correlates with cardiovascular disease and is also seen in lipomatosis. Fat-containing hilar lesions include lipomas, angiomyolipomas, and less commonly other tumors which engulf sinus fat. Mesenchymal hilar tumors are rare. MR imaging diagnosis is generally not possible, although anatomic relations should be described to guide diagnosis by percutaneous biopsy or surgery.

Arterial Wall Imaging in Pediatric Stroke.

Arteriopathy is common in childhood arterial ischemic stroke (AIS) and predicts stroke recurrence. Currently available vascular imaging techniques mainly image the arterial lumen rather than the vessel wall and have a limited ability to differentiate among common arteriopathies. We aimed to investigate the value of a magnetic resonance imaging-based technique, namely noninvasive arterial wall imaging (AWI), for distinguishing among arteriopathy subtypes in a consecutive cohort of children presenting with AIS. Children with confirmed AIS and magnetic resonance angiography underwent 3-Tesla AWI including T1-weighted 2-dimensional fluid-attenuated inversion recovery fast spin echo sequences pre- and post-gadolinium contrast. AWI characteristics, including wall enhancement, wall thickening, and luminal stenosis, were documented for all. Twenty-six children with AIS had AWI. Of these, 9 (35%) had AWI enhancement. AWI enhancement was associated with anterior circulation magnetic resonance angiography abnormality and cortical infarction in 8 of 9 (89%) children and normal magnetic resonance angiography with posterior circulation subcortical infarction in 1 (1 of 9; 11%) child. AWI enhancement was not seen in 17 (65%), 10 (59%) of whom had an abnormal magnetic resonance angiography. Distinct patterns of pre- and postcontrast signal abnormality were demonstrated in the vessel wall in the region of interest in children with transient cerebral arteriopathy, arterial dissection, primary central nervous system angiitis, dissecting aneurysm, and cardioembolic stroke. AWI is a noninvasive, high-resolution magnetic resonance AWI technique, which can be successfully used in children presenting with AIS. Patterns of AWI enhancement are recognizable and associated with specific AIS pathogeneses. Further studies are required to assess the additional diagnostic utility of AWI over routine vascular imaging techniques, in childhood AIS.

Correlation between electrical conductivity and apparent diffusion coefficient in breast cancer: effect of necrosis on magnetic resonance imaging.

To investigate the correlation between conductivity and ADC in invasive ductal carcinoma according to the presence of necrosis on MRI. Eighty-one women with invasive ductal carcinoma ≥1 cm on T2-weighted fast spin echo sequence of preoperative MRI were included. Phase-based MR electric properties tomography was used to reconstruct conductivity. Mean ADC was measured. Necrosis was defined as an area with very high T2 signal intensity. The relationship between conductivity and ADC was examined using Spearman's correlation coefficient (r). Multiple linear regression analysis was performed to identify factors associated with conductivity or ADC. In the total group, conductivity showed negative correlation with ADC (r = -0.357, p = 0.001). This correlation was maintained in the subgroup without necrosis (n = 53, r = -0.455, p = 0.001), but not in the subgroup with necrosis (n = 28, r = -0.080, p = 0.687). The correlation between the two parameters was different according to necrosis (r = -0.455 vs -0.080, p = 0.047). HER2 enriched subtype was independently associated with conductivity (p = 0.029). Necrosis on MRI was independently associated with ADC (p = 0.027). Conductivity shows negative correlation with ADC that is abolished by the presence of necrosis on MRI. • Electric conductivity showed negative correlation with ADC • However, the correlation was abolished by the presence of necrosis on MRI • HER2-enriched subtype was independently associated with conductivity • Necrosis on MRI was independently associated with ADC.

Nigrosome Imaging and Neuromelanin Sensitive MRI in Diagnostic Evaluation of Parkinsonism.

Recent developments in magnetic resonance imaging (MRI) techniques have offered new research opportunities to visualize in vivo substantia nigra pathology in Parkinson's disease (PD). This paper summarizes the main findings of nigrosome imaging and neuromelanin sensitive MRI studies in patients with PD and other parkinsonisms. The PubMed database was searched from 2005 to 2017 using the following keywords: Parkinson's disease and parkinsonism, in combination with MRI, nigrosome, neuromelanin, and iron. Only publications in English were included. Nigrosome or dorsal nigral hyperintensity abnormalities are studied using T2* and susceptibility weighted imaging MRI sequences in most studies, whereas Neuromelanin imaging is usually performed using T1-weighted fast spin echo sequence. Nigrosome abnormalities have been consistently demonstrated in PD patients, and nigrosome imaging has high sensitivity and specificity in distinguishing PD from healthy controls, though it is unable to reliably separate PD from atypical parkinsonisms. Reduced neuromelanin-related signals and/or volume loss in neuromelanin containing structures have been found in PD patients, and neuromelanin sensitive MRI imaging can also discriminate PD patients from healthy controls with high accuracy, though there is a degree of heterogeneity in the imaging findings. Preliminary findings suggested that longitudinal change of neuromelanin signal could be detected in PD, raising the possibility of using it as a marker of disease progression. Nigrosome imaging and neuromelanin sensitive MRI are promising tools to study nigral pathology and to improve the diagnosis of PD. However, further studies are required to standardize analysis approaches, confirm longitudinal changes, and assess their generalizability.

How Do MRI-Detected Subchondral Bone Marrow Lesions (BMLs) on Two Different MRI Sequences Correlate with Clinically Important Outcomes?

The aim of this study is to describe the association of bone marrow lesions (BMLs) present on two different MRI sequences with clinical outcomes, cartilage defect progression, cartilage volume loss over 2.7 years, and total knee replacement (TKR) over 13.3years. 394 participants (50-80years) were assessed at baseline and 2.7years. BML presence at baseline was scored on T1-weighted fat-suppressed 3D gradient-recalled acquisition (T1) and T2-weighted fat-suppressed 2D fast spin-echo (T2) sequences. Knee pain, function, and stiffness were assessed using WOMAC. Cartilage volume and defects were assessed using validated methods. Incident TKR was determined by data linkage. BMLs were mostly present on both MRI sequences (86%). BMLs present on T2, T1, and both sequences were associated with greater knee pain and functional limitation (odds ratio = 1.49 to 1.70; all p < 0.05). Longitudinally, BMLs present on T2, T1, and both sequences were associated with worsening knee pain (β = 1.12 to 1.37, respectively; p < 0.05) and worsening stiffness (β = 0.45 to 0.52, respectively; all p < 0.05) but not worsening functional limitation or total WOMAC. BMLs present on T2, T1, and both sequences predicted site-specific cartilage defect progression (relative risk = 1.22 to 4.63; all p < 0.05) except at the medial tibial and inferior patellar sites. Lateral tibial and superior patellar BMLs present on T2, T1, and both sequences predicted site-specific cartilage volume loss (β = - 174.77 to - 140.67; p < 0.05). BMLs present on T2, T1, and both sequences were strongly associated with incident TKR. BMLs can be assessed on either T2- or T1-weighted sequences with no clinical predictive advantage of either sequence.

Coronary magnetic resonance imaging after routine implantation of bioresorbable vascular scaffolds allows non-invasive evaluation of vascular patency.

BackgroundEvaluation of recurrent angina after percutaneous coronary interventions is challenging. Since bioresorbable vascular scaffolds (BVS) cause no artefacts in magnetic resonance imaging (MRI) due to their polylactate-based backbone, evaluation of vascular patency by MRI might allow for non-invasive assessment and triage of patients with suspected BVS failure.MethodsPatients with polylactate-based ABSORB-BVS in proximal coronary segments were examined with 3 Tesla MRI directly (baseline) and one year after implantation. For assessment of coronary patency, a high-resolution 3D spoiled gradient echo pulse sequence with fat-saturation, T2-preparation (TE: 40 ms), respiratory and end-diastolic cardiac gating, and a spatial resolution of (1.08 mm)3 was positioned parallel to the course of the vessel for bright blood imaging. In addition, a 3D navigator-gated T2-weighted variable flip angle turbo spin echo (TSE) sequence with dual-inversion recovery black-blood preparation and elliptical k-space coverage was applied with a voxel size of (1.14 mm)3. For quantitative evaluation lumen diameters of the scaffolded areas were measured in reformatted bright and black blood MR angiography data.Results11 patients with implantation of 16 BVS in the proximal coronary segments were included, of which none suffered from major adverse cardiac events during the one year follow up. Vascular patency in all segments implanted with BVS could be reliably assessed by MRI at baseline and after one year, whereas segments with metal stents could not be evaluated due to artefacts. Luminal diameter within the BVS remained constant during the one year period. One patient with atypical angina after BVS implantation was noninvasively evaluated showing a patent vessel, also confirmed by coronary angiography.ConclusionsCoronary MRI allows contrast-agent free and non-invasive assessment of vascular patency after ABSORB-BVS implantation. This approach might be supportive in the triage and improvement of diagnostic workflows in patients with postinterventional angina and scaffold implantation.Trial registrationGerman Register of Clinical Studies DRKS00007456

Simultaneous multi-slice accelerated turbo spin echo of the knee in pediatric patients.

To compare knee MRI performed with the integrated parallel acquisition technique (PAT) and simultaneous multislice (SMS) turbo spin echo (TSE) T2-weighted (T2w) sequences with conventional TSE sequences in pediatric patients. This was a retrospective IRB-approved study. Seventy-four subjects (26 male, 48 female, mean age 15.3years, range 8-20) underwent 3-T MRI of the knee with a T2w TSE pulse sequence prototype with four-fold PAT and SMS acceleration as well as the standard PAT-only accelerated sequences. Images were anonymized and two study folders were created: one examination with only T2w PAT2 images (conventional examination) and one examination with only T2w SMS2/PAT2 sequences (SMS examination). Two readers rated examinations for 15 specific imaging findings and 5 quality metrics. Interreader agreement was measured. Signal to noise (SNR) and contrast to noise (CNR) were measured for SMS and conventional T2w sequences. Consensus review demonstrated diagnostic quality performance of SMS examinations with respect to all 15 structures. Average area under the curve (AROC) was 0.95 and 0.97 for readers 1 and 2, respectively. The conventional sequence was favored over SMS for four out of five quality metrics (p < 0.001). SNR and CNR were higher for the conventional sequences compared to SMS. SMS accelerated T2w TSE sequences offer a faster alternative for knee imaging in pediatric patients without compromise in diagnostic performance despite diminished SNR. The four-fold acceleration of SMS is beneficial to pediatric patients who often have difficulty staying still for long MRI examinations.

Evaluation of the Subscapularis Tendon Tears on 3T Magnetic Resonance Arthrography: Comparison of Diagnostic Performance of T1-Weighted Spectral Presaturation with Inversion-Recovery and T2-Weighted Turbo Spin-Echo Sequences.

ObjectiveTo compare the T1-weighted spectral presaturation with inversion-recovery sequences (T1 SPIR) with T2-weighted turbo spin-echo sequences (T2 TSE) on 3T magnetic resonance arthrography (MRA) in the evaluation of the subscapularis (SSC) tendon tear with arthroscopic findings as the reference standard.Materials and MethodsThis retrospective study included 120 consecutive patients who had undergone MRA within 3 months between April and December 2015. Two musculoskeletal radiologists blinded to the arthroscopic results evaluated T1 SPIR and T2 TSE images in separate sessions for the integrity of the SSC tendon, examining normal/articular-surface partial-thickness tear (PTTa)/full-thickness tear (FTT). Diagnostic performance of T1 SPIR and T2 TSE was calculated with arthroscopic results as the reference standard, and sensitivity, specificity, and accuracy were compared using the McNemar test. Interobserver agreement was measured with kappa (κ) statistics.ResultsThere were 74 SSC tendon tears (36 PTTa and 38 FTT) confirmed by arthroscopy. Significant differences were found in the sensitivity and accuracy between T1 SPIR and T2 TSE using the McNemar test, with respective rates of 95.9–94.6% vs. 71.6–75.7% and 90.8–91.7% vs. 79.2–83.3% for detecting tear; 55.3% vs. 31.6–34.2% and 85.8% vs. 78.3–79.2%, respectively, for FTT; and 91.7–97.2% vs. 58.3–61.1% and 89% vs. 78–79.3%, respectively, for PTTa. Interobserver agreement for T1 SPIR was almost perfect for T1 SPIR (κ = 0.839) and substantial for T2 TSE (κ = 0.769).ConclusionT1-weighted spectral presaturation with inversion-recovery sequences is more sensitive and accurate compared to T2 TSE in detecting SSC tendon tear on 3T MRA.

T2-weighted spoiled gradient echo sequence (MERGE): A different perspective on the forensic age estimation

Introduction Age estimation methods using MRI are dependent on staging systems used in T1, T2 and fast spin-echo proton density-weighted sequences. The staging system created by Dedouit [1] from images obtained by fast spin-echo proton density-weighted MRI sequences depends on the assessment of horizontal cartilage hyperintensity. Images obtained by this method, detecting 1.5 mm hyperintensity thickness, and in some cases, detecting continuity of hyperintensity could be challenging. The purpose of this preliminary study was to investigate the utility of T2-weighted spoiled gradient echo sequence in determining the degree of ossification of epiphyses. Material and methods In this study, fast spin-echo proton density-weighted and MERGE T2-weighted spoiled gradient echo sequences of the knee of 25 patients (10–30 years, 10 female and 15 male) were evaluated using Dedouit et al.’s [1] five-stage method. Results The horizontal cartilages assessed with MERGE exhibited hyperintensity and clearly visible borders ( Fig. 1 ). Stage 2 and 3 were easily distinguishable and the epiphyseal scar line observed in stage 5 (complete fusion) was easily observed in contrast to the fast spin-echo proton density-weighted sequence. The hyperintense line that was assessed in fast spin-echo proton density-weighted sequence in stage 3 cases was seen as continuous and intermittent hypointense line in MERGE sequence. It was suggested that substages may be necessary for the distinction of stage 3 and 4. Discussion At present, due to the ethical concerns, non-ionized methods (ultrasound and MRI) are more frequently used in living individuals’ age estimations. MRI assessments in spoiled T2-weighted spoiled gradient echo sequence for age determination may be advantageous in the examination of epiphyseal lines and may produce different options in staging.

3D hybrid profile order technique in a single breath-hold 3D T2-weighted fast spin-echo sequence: Usefulness in diagnosis of small liver lesions

PurposeWe compared the efficacy of three-dimensional (3D) isotropic T2-weighted fast spin-echo imaging using a 3D hybrid profile order technique with a single-breath-hold (3D-Hybrid BH) with a two-dimensional (2D) T2-weighted fast spin-echo conventional respiratory-gated (2D-Conventional RG) technique for visualising small liver lesions. Materials and methodsThis study was approved by our institutional review board. The requirement to obtain written informed consent was waived. Fifty patients with small (≤15mm) hepatocellular carcinomas (HCC) (n=26), or benign cysts (n=24), had undergone hepatic MRI including both 2D-Conventional RG and 3D-Hybrid BH. We calculated the signal-to-noise ratio (SNR) and tumour-to-liver contrast (TLC). The diagnostic performance of the two protocols was analysed. ResultsThe image acquisition time was 89% shorter with the 3D-Hybrid BH than with 2D-Conventional RG. There was no significant difference in the SNR between the two protocols. The area under the curve (AUC) of the TLC was significantly higher on 3D-Hybrid BH than on 2D-Conventional RG. ConclusionThe 3D-Hybrid BH sequence significantly improved diagnostic performance for small liver lesions with a shorter image acquisition time without sacrificing accuracy.

Peripheral nerve involvement in multiple sclerosis: Demonstration by magnetic resonance neurography.

To detect and quantify peripheral nerve lesions in multiple sclerosis (MS) by magnetic resonance neurography (MRN). Thirty-six patients diagnosed with MS based on the 2010 McDonald criteria (34 with the relapsing-remitting form, 2 with clinically isolated syndrome) with and without disease-modifying treatment were compared to 35 healthy age-/sex-matched volunteers. All patients underwent detailed neurological and electrophysiological examinations. Three Tesla MRN with large anatomical coverage of both legs and the lumbosacral plexus was performed by using 2-dimensional (2D) fat-saturated, T2-weighted (T2w) and dual echo turbo spin echo sequences as well as a 3D T2-weighted, fat-saturated SPACE sequence. Besides qualitative visual nerve assessment, a T2w signal quantification was performed by calculation of proton spin density and T2 relaxation time. Nerve diameter was measured as a morphometric criterion. T2w hyperintense nerve lesions were detectable in all MS patients, with a mean lesion number at thigh level of 151.5 ± 5.7 versus 19.1 ± 2.4 in controls (p < 0.0001). Nerve proton spin density was higher in MS (tibial/peroneal: 371.8 ± 7.7/368.9 ± 8.2) versus controls (tibial/peroneal: 266.0 ± 11.0/276.8 ± 9.7, p < 0.0001). In contrast, T2 relaxation time was significantly higher in controls (tibial/peroneal: 82.0 ± 2.1/78.3 ± 1.7) versus MS (tibial/peroneal: 64.3 ± 1.0/61.2 ± 0.9, p < 0.0001). Proximal tibial and peroneal nerve caliber was higher in MS (tibial: 52.4 ± 2.1mm2 , peroneal: 25.4 ± 1.3mm2 ) versus controls (tibial: 45.2 ± 1.4mm2 , p < 0.0015; peroneal: 21.3 ± 0.7mm2 , p = 0.0049). Peripheral nerve lesions could be visualized and quantified in MS in vivo by high-resolution MRN. Lesions are defined by an increase of proton spin density and a decrease of T2 relaxation time, indicating changes in the microstructural organization of the extracellular matrix in peripheral nerve tissue in MS. By showing involvement of the peripheral nervous system in MS, this proof-of-concept study may offer new insights into the pathophysiology and treatment of MS. Ann Neurol 2017;82:676-685.

Differentiation of Acute Osteoporotic and Malignant Vertebral Fractures by Quantification of Fat Fraction With a Dixon MRI Sequence.

The purpose of this study was to differentiate malignant compression fractures from acute osteoporotic compression fractures of the spine by use of a Dixon MRI sequence to quantify fat fraction (FF). Forty-four vertebral compression fractures were assessed with turbo spin-echo T1-weighted and six-echo Dixon sequences for FF quantification at 3-T MRI. The fractures were divided into malignant compression fractures (n = 24) and acute osteoporotic compression fractures (n = 20). Two radiologists independently measured quantitative parameters from ROIs in the fractures, including the T1 signal intensity of the fracture, the FF of the fracture, and the FF ratio (fracture FF divided by normal marrow FF). The mean values of the parameters were compared between the two groups, interobserver reliability between two radiologists was assessed, ROC curves were analyzed, and logistic regression analysis was performed. The fracture FF and FF ratio of malignant compression fractures were significantly lower than those of acute osteoporotic compression fractures (fracture FF, 2.73% vs 14.36% [p < 0.001]; FF ratio, 0.05 vs 0.22 [p < 0.001]). There was no difference in T1 signal intensity of the fracture. The ROC AUC of fracture FF was 0.98 and of FF ratio was 0.95. In logistic regression analysis, fracture FF remained a significant variable that could be used to independently differentiate malignant from acute osteoporotic compression fractures (odds ratio, 0.33; p < 0.005). FF and FF ratio obtained from FF maps obtained with a six-echo Dixon MRI sequence may be useful for differentiating acute osteoporotic compression fractures from malignant compression fractures.

Temporary Hearing Threshold Shift in Healthy Volunteers with Hearing Protection Caused by Acoustic Noise Exposure during 3-T Multisequence MR Neuroimaging.

Purpose To determine whether a single 51-minute exposure to acoustic noise during 3-T multisequence magnetic resonance (MR) neuroimaging could affect the hearing threshold of healthy adults with earplugs and sponge mats as hearing protection. Materials and Methods With earplugs and motion-refraining sponge mats as hearing protection, 26 healthy young adults underwent 3-T MR neuroimaging imaging that included T1-weighted three-dimensional gradient-echo sequence, T2-weighted fast spin-echo sequence, diffusion-tensor imaging, diffusion-kurtosis imaging, T2*-weighted three-dimensional multiecho gradient-echo sequence, and blood oxygen level-dependent imaging. Automated auditory brainstem response (ABR) was used to measure the hearing thresholds within 24 hours before, within 20 minutes after, and 25 days after the MR examination. One-way repeated-measure analysis of variance with Bonferroni adjustment was used to compare automated ABR results among the three tests and partial η2 (ηp2) was reported as a measure of effect size. Results Automated ABR results showed significantly increased mean threshold shift of 5.0 dB ± 8.1 (standard deviation) (left ear: 4.8 dB ± 9.2 [95% confidence interval: 1.09, 8.53], ηp2 = 0.221, P = .013; right ear: 5.2 dB ± 6.9 [95% confidence interval: 2.36, 8.02], ηp2 = 0.364, P = .001) immediately after the MR examination compared with the baseline study. This shift is below the temporary threshold shift of 40-50 dB that is associated with cochlea nerve changes. Automated ABR obtained at day 25 after MR imaging showed no significant differences from baseline (left ear: -2.3 dB ± 8.6 [95% confidence interval: -5.79, 1.78], ηp2 = 0.069, P = .185; right ear: 0.4 dB ± 7.3 [95% confidence interval: -3.35, 2.58], ηp2 = 0.003, P = .791). Conclusion A 3-T MR neuroimaging examination with the acoustic noise at equivalent sound pressure level of 103.5-111.3 dBA lasting 51 minutes can cause temporary hearing threshold shift in healthy volunteers with hearing protection. © RSNA, 2017.

Reduced metallic artefacts in 3 T knee MRI using fast spin-echo multi-point Dixon compared to fast spin-echo T2-weighted sequences

To compare multi-point Dixon magnetic resonance imaging (MRI) and fast spin-echo (FSE) T2-weighted imaging (WI) with regard to the size of metallic artefacts when imaging the knee joint. A total of 42 patients who underwent anterior cruciate ligament (ACL) reconstruction and follow-up imaging with 3T MRI using the multi-point Dixon technique was included in this retrospective study. The maximal distance of the image distortion area around the metallic artefact was measured (interference screw of femoral tunnel area) on sagittal images of both FSE T2WI (T2WI and fat-suppressed [FS] T2WI) and multi-point Dixon (water only image and in-phase image) sequences. The maximal distance of the image distortion were compared using paired t-tests across the image sequences (multi-point Dixon water only image versus FS T2WI and multi-point Dixon in-phase image versus T2WI). The mean distance of the image distortion from metallic artefacts regardless of the image sequence ranged from 16.6mm to 24.5mm (Table2). The mean distances measured by two readers on multi-point Dixon (water only image) sequences were significantly shorter than those in FS T2WI sequences (p<0.001). In contrast, the mean distances measured by two readers on multi-point Dixon (in-phase image) sequences did not differ from those of T2WI (p>0.05) sequences. The water-only image of multi-point Dixon technique reduces the amount of metallic artefacts compared to that in FS FSE T2WI sequences; however, the metallic artefacts were not significantly different between in-phase images of multi-point Dixon and FSE T2WI.