Assessment of bone marrow oedema-like lesions using MRI in patellofemoral knee osteoarthritis: comparison of different MRI pulse sequences

Objective:To compare bone marrow oedema-like lesion (BML) volume in subjects with symptomatic patellofemoral (PF) knee osteoarthritis (OA) using four different MRI sequences and to determine reliability of BML volume assessment using these sequences and their correlation with pain.Methods:76 males and females (mean age 55.8 years) with symptomatic patellofemoral knee OA had 1.5 T MRI scans. PD fat suppressed (FS), STIR, contrast-enhanced (CE) T₁W FS, and 3D T₁W fast field echo (FFE) sequences were obtained. All sequences were assessed by one reader, including repeat assessment of 15 knees using manual segmentation and the measurements were compared. We used random-effects panel linear regression to look for differences in the log-transformed BML volume (due to positive skew in the BML volume distribution) between sequences and to determine associations between BML volumes and knee pain.Results:58 subjects had PF BMLs present on at least one sequence. Median BML volume measured using T₁W FFE sequence was significantly smaller (224.7 mm³, interquartile range [IQR] 82.50–607.95) than the other three sequences. BML volume was greatest on the CE sequence (1129.8 mm³, IQR 467.28–3166.02). Compared to CE sequence, BML volumes were slightly lower when assessed using PDFS (proportional difference = 0.79; 95% confidence interval [CI] 0.62, 1.01) and STIR sequences (proportional difference = 0.85; 95% CI 0.67, 1.08). There were strong correlations between BML volume on PDFS, STIR, and CE T₁W FS sequences (ρs = 0.98). Correlations were lower between these three sequences and T₁W FFE (ρs = 0.80–0.81). Intraclass correlation coefficients were excellent for proton density fat-suppressed, short-tau inversion recovery, and CE T₁W FS sequences (0.991–0.995), while the ICC for T₁W FFE was good at 0.88. We found no significant association between BML volumes assessed using any of the sequences and knee pain.Conclusion:T₁W FFE sequences were less reliable and measured considerably smaller BML volume compared to other sequences. BML volume was larger when assessed using the contrast enhanced T₁W FS though not statistically significantly different from BMLs when assessed using PDFS and STIR sequences.Advances in knowledge:This is the first study to assess BMLs by four different MRI pulse sequences on the same data set, including different fluid sensitive sequences and gradient echo type sequence.     

T2WI 3.0T盆腔风车采集技术在子宫腺肌症及子宫肌瘤中的应用价值

目的探讨3.0 T风车采集(MVXD)技术T2WI在子宫腺肌症及子宫肌瘤中的应用价值。方法前瞻性收集2018年3月至5月北京协和医院超声证实有子宫肌瘤或临床疑诊为子宫腺肌症的患者,均在围排卵期行盆腔3.0 T MRI检查,采集常规轴面快速自旋回波(TSE)T2WI、轴面MVXD T2WI、矢状面TSE T2WI、矢状面MVXD T2WI图像。2名医师分别对4个序列图像进行子宫轮廓清晰程度、运动伪影、对病变的识别能力、诊断确信程度及整体图像质量评分。采用Cohen Kappa法评价2名医师间评分的一致性,采用Wilcoxon配对符号秩和检验比较采用常规TSE及轴面MVXD序列采集T2WI图像质量的差异。结果20例患者纳入研究,均采集了常规轴面TSE T2WI及轴面MVXD T2WI;19例采集了常规矢状面TSE T2WI及矢状面MVXD T2WI。9例仅存在明显子宫腺肌症病灶,6例仅存在明显子宫肌瘤,5例同时合并子宫腺肌症及子宫肌瘤。和传统的常规TSE序列相比,2名医师采用MVXD序列采集的矢状面T2WI和轴面T2WI中,均对子宫轮廓清晰程度、运动伪影、整体图像质量方面的评分更高,差异有统计学意义(P<0.05)。2名医师对图像评价的Kappa值为0.615~0.971,一致性均为好或非常好。结论将T2WI MVXD技术应用于子宫肌瘤或子宫腺肌症患者,相较于常规T2WI技术有利于改善图像质量,且不牺牲对病变的识别、诊断能力。     

Evaluation of Focal Cervical Spinal Cord Lesions in Multiple Sclerosis: Comparison of White Matter–Suppressed T1 Inversion Recovery Sequence versus Conventional STIR and Proton Density–Weighted Turbo Spin-Echo Sequences

BACKGROUND AND PURPOSE:Conventional MR imaging of the cervical spinal cord in MS is challenged by numerous artifacts and interreader variability in lesion counts. This study compares the relatively novel WM-suppressed T1 inversion recovery sequence with STIR and proton density–weighted TSE sequences in the evaluation of cervical cord lesions in patients with MS.MATERIALS AND METHODS:Retrospective blinded analysis of cervical cord MR imaging examinations of 50 patients with MS was performed by 2 neuroradiologists. In each patient, the number of focal lesions and overall lesion conspicuity were measured in the STIR/proton density–weighted TSE and WM-suppressed T1 inversion recovery sequence groups. Independent side-by-side comparison was performed to categorize the discrepant lesions as either “definite” or “spurious.” Lesion contrast ratio and edge sharpness were independently calculated in each sequence.RESULTS:Substantial interreader agreement was noted on the WM-suppressed T1 inversion recovery sequence (κ = 0.82) compared with STIR/proton density–weighted TSE (κ = 0.52). Average lesion conspicuity was better on the WM-suppressed T1 inversion recovery sequence (conspicuity of 3.1/5.0 versus 3.7/5.0, P < .01, in the WM-suppressed T1 inversion recovery sequence versus STIR/proton density–weighted TSE, respectively). Spurious lesions were more common on STIR/proton density–weighted TSE than on the WM-suppressed T1 inversion recovery sequence (23 and 30 versus 3 and 4 by readers 1 and 2, respectively; P < .01). More “definite” lesions were missed on STIR/proton density–weighted TSE compared with the WM-suppressed T1 inversion recovery sequence (37 and 38 versus 3 and 6 by readers 1 and 2, respectively). Lesion contrast ratio and edge sharpness were highest on the WM-suppressed T1 inversion recovery sequence.CONCLUSIONS:There is better interreader consistency in the lesion count on the WM-suppressed T1 inversion recovery sequence compared with STIR/proton density–weighted TSE sequences. The focal cord lesions are visualized with better conspicuity due to better contrast ratio and edge sharpness. There are fewer spurious lesions on the WM-suppressed T1 inversion recovery sequence compared with STIR/proton density–weighted TSE. The WM-suppressed T1 inversion recovery sequence could potentially be substituted for either STIR or proton density–weighted TSE sequences in routine clinical protocols.

The cervical spinal cord is commonly affected in multiple sclerosis, which is often associated with an increase in clinical disability.^1–3 A focal form of involvement is more common in the relapsing-remitting variant of MS compared with the other less common MS subtypes.⁴ MS lesions undergo complex cycles of inflammation, followed by variable extent of repair and, therefore, have heterogeneity in the prolongation of T1 and T2 relaxation times, which influence their conspicuity on the standard MR imaging sequences such as STIR and proton density–weighted TSE (PDWTSE).The PDWTSE sequence with a lower TE is better than the longer TE T2-weighted sequences in the detection of focal MS lesions in the spinal cord.^5,6 STIR has intrinsic sensitivity to T1 shortening effects in addition to T2 prolongation effects and improves the lesion contrast compared with T2-weighted sequences, translating to a better interreader agreement in the assessment of the extent of disease.⁷ Nevertheless, artifacts and lower lesion conspicuity prevalent on these sequences may cause variability in the clinical evaluation of lesion burden, which is difficult to resolve in the absence of a true reference standard.⁸ Reliable characterization of the lesion burden on follow-up examinations is therefore important for assessing treatment efficacy and optimizing treatment strategies.Many novel sequences have been devised attempting to improve imaging quality and lesion conspicuity with fewer artifacts and with a reasonable acquisition time. In a smaller study population, the WM-suppressed T1 inversion recovery (WMS) sequence has shown improvement in lesion conspicuity over STIR and dual-echo fast spin-echo.⁹ While the principles of the contrast mechanism on WMS are similar to those on STIR, the sequence parameters of WMS are optimized for better intramedullary imaging. In WMS, the section-selective inversion pulse is applied at 385 ms to suppress the background signal from white matter, whereas in STIR, it is applied at 160 ms to optimize fat suppression.¹⁰ A shorter TE is used in WMS compared with STIR or PDWTSE, which further increases the T1-weighting of the sequence, which acts as the main contrast mechanism in this long TR/short TE sequence.^11,12 MS lesions have increased T1 relaxation times and thus are not suppressed with a white matter selective inversion recovery suppression pulse. There is a need for larger scale evaluation of WMS for clinical utility in routine practice against the standard sequences (STIR and PDWTSE) in the detection of MS cord lesions. The purpose of this retrospective study was to compare the utility of WMS compared with routinely used STIR and PDWTSE sequences in the evaluation of focal cervical cord lesions is MS.     

Fast spin-echo triple echo dixon: Initial clinical experience with a novel pulse sequence for simultaneous fat-suppressed and nonfat-suppressed T2-weighted spine magnetic resonance imaging

Purpose

To evaluate a prototype fast spin‐echo (FSE) triple‐echo Dixon (FTED) technique for T2‐weighted spine imaging with and without fat suppression compared to conventional T2‐weighted fast recovery (FR) FSE and short‐tau inversion recovery (STIR) imaging.

Materials and Methods

Sixty‐one patients were referred for spine magnetic resonance imaging (MRI) including sagittal FTED (time 2:26), STIR (time 2:42), and T2 FRFSE (time 2:55). Two observers compared STIR and FTED water images and T2 FRFSE and FTED T2 images for overall image quality, fat suppression, anatomic sharpness, motion, cerebrospinal fluid (CSF) flow artifact, susceptibility, and disease depiction.

Results

On FTED images water and fat separation was perfect in 58 (.95) patients. Compared to STIR, the FTED water images demonstrated less motion in 57 (.93) of 61 patients (P < 0.05), better anatomic sharpness in 51 (.84) and patients (P < 0.05), and less CSF flow artifact in 7 (.11) P < 0.05) patients. There was no difference in fat suppression or chemical shift artifact. T2 FRFSE and FTED T2 images showed equivalent motion, CSF flow, and chemical shift artifact. Lesion depiction was equivalent on FTED water and STIR images and FTED T2 and T2 FRFSE images.

Conclusion

FTED efficiently provides both fat‐suppressed and nonfat‐suppressed T2‐weighted spine images with excellent image quality, equal disease depiction, and 56% reduction in scan time compared to conventional STIR and T2 FRFSE. J. Magn. Reson. Imaging 2011;33:390–400. © 2011 Wiley‐Liss, Inc.     

Fat suppression at 2D MR imaging of the hands: Dixon method versus CHESS technique and STIR sequence

ObjectiveTo compare the effectiveness of fat suppression and the signal-to-noise ratio (SNR) of the Dixon method with those of the CHESS (Chemical Shift-Selective) technique and STIR (Short Tau Inversion Recovery) sequence in hands of normal subjects at 2D MR imaging.Material and methods14 healthy volunteers (mean age of 29.4 years) consented to have both hands prospectively imaged with SE T1 Dixon, T1 CHESS, T2 Dixon, T2 CHESS and STIR sequences in a 1.5T MR scanner. Three radiologists scored the effectiveness of fat suppression in bone marrow (EFS^BM) and soft tissues (EFS^ST) in 20 joints per subject. One radiologist measured the SNR in 10 bones per subject. Statistical analysis used two-way ANOVA with random effects, paired t-test and observed agreement to assess differences in effectiveness of fat suppression, differences in SNR and inter-observer agreement.ResultsEFS^BM was statistically significantly higher for T1 Dixon than for T1 CHESS and for T2 Dixon than for T2 CHESS (p < 0.0001). EFS^BM was significantly higher for T2 Dixon than for STIR in the coronal plane (p = 0.0020). The SNR was significantly higher for T1 Dixon than for T1 CHESS and for T2 Dixon than for STIR (p  <  0.0001). The SNR was significantly lower for T2 Dixon than for T2 CHESS (p < 0.0001).ConclusionThe Dixon method yields more effective fat suppression and higher SNR than the CHESS technique at 2D T1-weighted MR imaging of the hands. At T2-weighted MR imaging, fat suppression is more effective with the Dixon method while SNR is higher with the CHESS technique.     

MR breast imaging : a comparative analysis of conventional and parallel imaging acquisition

PURPOSE: The objective of this study was to compare conventional breast magnetic resonance imaging (MRI) with breast MRI acquired with the sensitivity-encoding (SENSE) technique on a 1.5-T MRI scanner in the same patient, on the basis of image quality and kinetics analysis. MATERIALS AND METHODS: Thirty-one patients with suspicious mammography and US findings were included in the study. Conventional breast MRI consisted of the following sequences: T1 (matrix, 288 x 512); T2 (matrix 225 x 512); short tau inversion recovery (STIR) (matrix 320 x 224) and dynamic T1 [2D fast-field echo (FFE)] (matrix 256 x 512; temporal resolution相似文献   

Uterine cervical carcinoma: a comparison of two- and three-dimensional T2-weighted turbo spin-echo MR imaging at 3.0 T for image quality and local-regional staging

Objective

To compare three-dimensional (3D) T2-weighted turbo spin-echo (TSE) with multiplanar two-dimensional (2D) T2-weighted TSE for the evaluation of invasive cervical carcinoma.

Methods

Seventy-five patients with cervical carcinoma underwent MRI of the pelvis at 3.0 T, using both 5-mm-thick multiplanar 2D (total acquisition time?=?12 min 25 s) and 1-mm-thick coronal 3D T2-weighted TSE sequences (7 min 20 s). Quantitative analysis of signal-to-noise ratio (SNR) and qualitative analysis of image quality were performed. Local-regional staging was performed in 45 patients who underwent radical hysterectomy.

Results

The estimated SNR of cervical carcinoma and the relative tumour contrast were significantly higher on 3D imaging (P?<?0.0001). Tumour conspicuity was better with the 3D sequence, but the sharpness of tumour margin was better with the 2D sequence. No significant difference in overall image quality was noted between the two sequences (P?=?0.38). There were no significant differences in terms of the diagnostic accuracy, sensitivity, and specificity of parametrial invasion, vaginal invasion, and lymph node metastases.

Conclusion

Multiplanar reconstruction 3D T2-weighted imaging is largely equivalent to 2D T2-weighted imaging for overall image quality and staging accuracy of cervical carcinoma with a shorter MR data acquisition, but has limitations with regard to the sharpness of the tumour margin.

Key Points

? 3D T2-weighted MR sequence is equivalent to 2D for cervical carcinoma staging. ? Coronal 3D acquisitions can reduce the examination time. ? SNR and relative tumour conspicuity were significantly higher on 3D sequences. ? Reformatted 3D T2-weighted imaging had limitations in sharpness of tumour margin.     

Investigating the Image Quality and Utility of Synthetic MRI in the Breast

PurposeSynthetic MRI reconstructs multiple sequences in a single acquisition. In the present study, we aimed to compare the image quality and utility of synthetic MRI with that of conventional MRI in the breast.MethodsWe retrospectively collected the imaging data of 37 women (mean age: 55.1 years; range: 20–78 years) who had undergone both synthetic and conventional MRI of T2-weighted, T1-weighted, and fat-suppressed (FS)-T2-weighted images. Two independent breast radiologists evaluated the overall image quality, anatomical sharpness, contrast between tissues, image homogeneity, and presence of artifacts of synthetic and conventional MRI on a 5-point scale (5 = very good to 1 = very poor). The interobserver agreement between the radiologists was evaluated using weighted kappa.ResultsFor synthetic MRI, the acquisition time was 3 min 28 s. On the 5-point scale evaluation of overall image quality, although the scores of synthetic FS-T2-weighted images (4.01 ± 0.56) were lower than that of conventional images (4.95 ± 0.23; P < 0.001), the scores of synthetic T1- and T2-weighted images (4.95 ± 0.23 and 4.97 ± 0.16) were comparable with those of conventional images (4.92 ± 0.27 and 4.97 ± 0.16; P = 0.484 and 1.000, respectively). The kappa coefficient of conventional MRI was fair (0.53; P < 0.001), and that of conventional MRI was fair (0.46; P < 0.001).ConclusionThe image quality of synthetic T1- and T2-weighted images was similar to that of conventional images and diagnostically acceptable, whereas the quality of synthetic T2-weighted FS images was inferior to conventional images. Although synthetic MRI images of the breast have the potential to provide efficient image diagnosis, further validation and improvement are required for clinical application.     

MR imaging of the knee in patients with medial unicompartmental arthroplasty: comparison among sequences at 1.5 T

Purpose

This study was done to test a series of magnetic resonance (MR) imaging sequences of the knee after medial unicompartmental arthroplasty.

Materials and methods

Four patients who had undergone Oxford III medial unicompartmental arthroplasty underwent 1.5-T MR imaging of the operated knee using coronal sequences: T1-weighted spin-echo (SE), T1-weighted turbo SE (TSE), proton-density (PD)- and T2-weighted TSE, T1-weighted gradient echo (GE), short-tau inversion recovery (STIR), multi echo data image combination (MEDIC), T2*-weighted GE, volumetric interpolated breath-hold examination (VIBE), and dual-echo steady state (DESS). For each sequence, we evaluated the visibility of the anatomical structures of the central pivot, lateral compartment, and anterior compartment using a semiquantitative score (0=total masking; 1=insufficient visibility; 2=sufficient visibility; 3=optimal visibility). The sum of the scores given to each sequence was divided by the maximal sum, obtaining a percentage visibility index. Friedman and sign tests were used for statistical analysis.

Results

MR examination time was 30–32 min. No patients reported pain, heat or other local discomfort. The visibility index ranged between 83% and 89% for the first four sequences without significant differences among them, 58% for STIR and 11%–36% for the last five sequences. Significant differences were found between each of the four first sequences and the remaining sequences (p<0.004) and between STIR and the last five sequences (p<0.008).

Conclusions

MR imaging of the knee after medial unicompartmental arthroplasty was not associated with adverse events. An imaging protocol including SE, TSE and STIR sequences could be used to study the knee with unicompartmental arthroplasty.     

Magnetic resonance imaging of ankle tendon pathology: benefits of additional axial short-tau inversion recovery imaging to reduce magic angle effects

Objectives

Our goals were to quantify the reduction of the magic angle effect using short-tau inversion recovery (STIR) imaging and to determine the value of adding an axial STIR sequence to the magnetic resonance imaging ankle protocol.

Materials and methods

Axial STIR sequences were used to measure normal tendon T1 and to estimate signal loss due to the inversion recovery preparation of our clinical protocol. In addition, 102 ankles were imaged with axial fat-suppressed intermediate-weighted fast spin echo and STIR sequences. Two radiologists analyzed the tendons for signal intensity, size, abnormalities, and magic angle effect. The diagnostic value and image quality of the two sequences were compared.

Results

We calculated a 50 % reduction of signal intensity in healthy tendons on the STIR sequence at TI?=?170 ms compared with TI?=?0 ms, explaining the decrease in the magic angle effect. Using the STIR sequence, our study demonstrated significantly lower signal intensity within the tendons, more precise tendon size, and a lower magic angle effect compared with the standard intermediate-weighted FSE sequence (p?<?0.001). Diagnostic classification of tendon abnormalities using the STIR sequences showed higher sensitivity (82.35 % vs 75.27 %) and better agreement with a reference standard than the intermediate-weighted sequences, and superior image quality (p?<?0.01).

Conclusions

Axial STIR sequences reduce magic angle effects and improve visualization of ankle tendon pathology.     

MR assessment of brain maturation: comparison of sequences.

PURPOSETo evaluate the role of short-inversion-time inversion-recovery (STIR) sequences in assessment of brain maturation.METHODSTwenty-seven infants and young children with normal neurologic development were examined by 1.5-T MR using a circularly polarized head coil. Axial T1-weighted and T2-weighted and spin-echo and STIR images were obtained. Signal intensity of different anatomic structures at individual sequences was classified relatively to reference sites and temporal sequence of signal intensity was observed.RESULTSSignal intensity changes on T1-weighted and T2-weighted spin-echo sequences occurred at ages described in various previous publications. On STIR images intensity changes became apparent at a time between T1-weighted and T2-weighted images. The advantages of the STIR sequence were improved assessment of myelination of subcortical cerebral white matter from 6 to 14 months and good contrast between white matter lesions and cerebrospinal fluid.CONCLUSIONOur results suggest that from 0 to 6 months myelination can be assessed best using a combination of T1-weighted and T2-weighted images; from 6 to 14 months a combination of T2-weighted and STIR images seems to be advantageous; after 14 months the use of only T2-weighted sequences is sufficient. After 14 months STIR images may be useful in detecting small periventricular white matter lesions or in cases with retarded myelination and isointensity between gray matter and white matter.     

Differentiation of hypointense nodules on gadoxetic acid-enhanced hepatobiliary-phase MRI using T2 enhanced spin-echo imaging with the time-reversed gradient echo sequence: An initial experience

PurposeTo optimize the flip angle (FA) of the T₂ enhanced spin-echo imaging using the time reversed gradient echo (T2FFE) and evaluate its utility for differentiating hypointensity nodules in the hepatobiliary phase (HBP) of gadoxetic acid-enhanced (Gd-EOB) MRI.Materials and methodsFirst, FA optimization of the T2FFE in the HBP was investigated by comparing signal-to-noise ratio (SNR) among different FAs using phantoms. The liver-to-muscle contrast ratios (CR_Liver-Muscle) and image quality among three FAs (20°, 50° and 80°) were compared using images of 10 patients. Next, the utility of the T2FFE with an optimized FA for differentiating hypointensity nodules in the HBP was assessed by comparing the lesion-to-liver contrast ratio (CR_Lesion-Liver) among cysts, hemangiomas, hepatocellular carcinomas, and metastatic tumors in 32 patients.ResultsSNR increased as FA increased, but leveled off at FAs of 50° and greater. The FA of 50° showed significantly better image quality scores than that of 80° (p < 0.05). After employing an FA of 50°, the CR_Lesion-Liver value indicated that the T2FFE depicted benign lesions as hyperintense and most malignant lesions as hypointense in relation with the liver parenchyma (p < 0.05).ConclusionThe T2FFE in the HBP of Gd-EOB-MRI is useful for differentiating benign and malignant liver lesions.     

Comparison of MRI sequences for evaluation of multiple sclerosis of the cervical spinal cord at 3 T

Purpose

Debate remains regarding the utility of the traditional STIR (short inversion time recovery) sequence in aiding MRI diagnosis of spinal cord lesions in patients with multiple sclerosis (MS) and this sequence is not included in the current imaging guidelines. A recent study proposed a T1 weighted STIR as a superior alternative to the traditional STIR and T2 fast spin echo (FSE). Thus, the aim of this study was to compare the sensitivity of T2, standard STIR and T1 weighted STIR sequences in the evaluation of MS plaques on our 3 T system.

Methods and materials

A retrospective analysis of patients with multiple sclerosis who presented to our institution over a period of 5 months and who had cervical cord lesions was undertaken. Patients had been examined with our institutional protocol which included T2 FSE, STIR and the recommended T1 STIR. Quantitative analysis of the lesions versus background cord using sample T-tests was performed for each sequence, and comparative analysis of the lesion contrast:background cord ratios of the 3 sequences (using two-way ANOVA tests) was performed.

Results

The T2 sequence was not as sensitive in detecting lesions versus the traditional STIR and T1 weighted STIR, with 10% of lesions not detected using statistical analysis (p < 0.05). The traditional STIR also demonstrated greater contrast ratios than the T2 sequence (p < 0.05) suggesting increased sensitivity. However, the T1 STIR demonstrated even greater contrast ratios than both the traditional STIR and T2 sequences (p < 0.05).

Conclusion

This study confirms earlier findings of the traditional STIRs increased sensitivity versus the T2 sequence. However, the new “T1 weighted STIR” appears to be even more sensitive than both these sequences showing potential promise as an alternative method to monitor demyelinating plaques of MS.     

Open 1.0-T versus closed 1.5-T cardiac MR: Image quality assessment

PurposeThe aim of this paper was to compare the open 1-T (O-1T) versus the closed 1.5-T (C-1.5T) cardiac magnetic resonance (MR).Patients/methodsThe MR examinations of two concurrent cohorts (each including 100 subjects) of patients with suspected or known cardiac disease were reviewed. Such examinations were obtained using O-1T or C-1.5T MRI. The bright-blood cine, T1-weighted (T1), T2-weighed short-tau inversion recovery (T2-STIR), late gadolinium enhancement (LGE) sequences were performed. Signal-to-noise ratio of blood (SNRb) or myocardium (SNRm), and contrast-to-noise ratio of myocardium (CNRm) were calculated. Subjective image quality (SIQ) of each sequence was graded as 0 = poor, 1 = intermediate, or 2 = optimal. Each examination was considered as diagnostic when the report answered the clinical question.ResultsC-1.5T was better than O-1T on cine for SNRb(median 172 versus 452), SNRm(71 versus 160) and CNRm (107 versus 265) and on T2-STIR for SNRb(10 versus 29), SNRm(74 versus 261) and CNRm(−67 versus −233)(P < 0.001). On LGE, SNRm was higher with O-1T than for C-1.5T (312 versus 79, P < 0.001) while CNR was lower (158 versus 389; P < 0.001). No significant differences were found for SNRb on LGE and both SNRm and CNRm on T1 (P ≥ 0.215). SIQ of O-1T was not significantly different from that of C-1.5T for both R1 and R2 for cine, T1, and LGE (P ≥ 0.157); for T2-STIR, SIQ of O-1T was significantly lower (P = 0.003). R1-R2 concordance was almost perfect (κ = 0.816–0.894), and all examinations were diagnostic.ConclusionEven though quantitative measurements mostly favored C-1.5T, the SIQ of O-1T was not significantly different for any sequence, with the only exception of T2-STIR.     

Quantitative and qualitative comparison of 3.0T and 1.5T MR imaging of the liver in patients with diffuse parenchymal liver disease

Purpose

The purpose of our study was to compare signal characteristics and image qualities of MR imaging at 3.0 T and 1.5 T in patients with diffuse parenchymal liver disease.

Materials and methods

25 consecutive patients with diffuse parenchymal liver disease underwent abdominal MR imaging at both 3.0 T and 1.5 T within a 6-month interval. A retrospective study was conducted to obtain quantitative and qualitative data from both 3.0 T and 1.5 T MRI. Quantitative image analysis was performed by measuring the signal-to-noise ratios (SNRs) and the contrast-to-noise ratios (CNRs) by the Students t-test. Qualitative image analysis was assessed by grading each sequence on a 3- and 4-point scale, regarding the presence of artifacts and image quality, respectively. Statistical analysis consisted of the Wilcoxon signed-rank test.

Results

the mean SNRs and CNRs of the liver parenchyma and the portal vein were significantly higher at 3.0 T than at 1.5 T on portal and equilibrium phases of volumetric interpolated breath-hold examination (VIBE) images (P < 0.05). The mean SNRs were significantly higher at 3.0 T than at 1.5 T on T1-weighted spoiled gradient echo (SGE) images (P < 0.05). However, there were no significantly differences on T2-weighted short-inversion-time inversion recovery (STIR) images. Overall image qualities of the 1.5 T non-contrast T1- and T2-weighted sequences were significantly better than 3.0 T (P < 0.01). In contrast, overall image quality of the 3.0 T post-gadolinium VIBE sequence was significantly better than 1.5 T (P < 0.01).

Conclusions

MR imaging of post-gadolinium VIBE sequence at 3.0 T has quantitative and qualitative advantages of evaluating for diffuse parenchymal liver disease.     

MR evaluation of vertebral metastases: T1-weighted,short-inversion-time inversion recovery,fast spin-echo,and inversion-recovery fast spin-echo sequences.

PURPOSETo compare the detectability of vertebral metastatic disease on T1-weighted, short-inversion-time inversion recovery (STIR), fast spin-echo (FSE), fat-saturated FSE, and inversion recovery FSE (IRFSE) MR sequences using percent contrast and contrast-to-noise ratios.METHODSPatients with proved metastatic disease underwent imaging on a 1.5-T MR system with sagittal T1-weighted (800/20/2 [repetition time/echo time/excitations]) (91 patients), STIR (1400/43/2; inversion time, 140) (91 patients), FSE (4000/180/2) (46 patients), fat-saturated FSE (4000/180/2) (16 patients), and IRFSE (29 patients) sequences. Percent contrast and contrast-to-noise ratio were calculated for the lesions. The number of metastatic lesions detected with each of the pulse sequences was also calculated.RESULTSMean percent contrast was, for T1-weighted sequence, -42.2 +/- 1%; STIR, 262 +/- 34%; FSE, 121 +/- 21%; fat-saturated FSE, 182 +/- 6%; and IRFSE, 272 +/- 47%. The mean contrast-to-noise ratio for T1-weighted was -4.63 +/- 1.7; STIR, 10.8 +/- .98; FSE, 4.16 +/- .76; fat-saturated FSE, 4.87 +/- .19; and IRFSE, 5.2 +/- .87. STIR and IRFSE showed the highest number of lesions, followed by T1-weighted, fat-saturated FSE, and FSE sequences. T1-weighted sequences showed 94%, FSE 55%, and fat-saturated FSE 78% of the lesions detected. Epidural metastatic lesions were better depicted on T1-weighted, FSE, and fat-saturated FSE sequences.CONCLUSIONSTIR was superior to both T1-weighted and FSE (with and without fat saturation) for detection of metastatic lesions, in terms of both percent contrast and contrast-to-noise ratio and visibility. IRFSE was equal to STIR for the detection of metastasis by both subjective and objective criteria. T1-weighted, FSE, and fat-saturated FSE sequences were superior to STIR and IRFSE in the detection of epidural metastatic disease. IRFSE provided faster scanning time, which could be translated into greater resolution.     

Fast spin-echo MR in the detection of vertebral metastases: comparison of three sequences.

PURPOSETo examine the relative capabilities for the detection of vertebral metastases of three available fast spin-echo sequences: T1-weighted fast spin-echo, short tau inversion recovery (STIR) fast spin-echo, and T2-weighted fast spin-echo sequences with chemical shift selective saturation pulse fat suppression.METHODSFourteen patients were evaluated prospectively over a 2-month period with T1-weighted fast spin-echo (four echo train, four acquisitions, 1 min 59 sec-2 min 37 sec). STIR fast spin-echo (16 echo train, four acquisitions, 2 min 30 sec-3 min 19 sec), and T2-weighted fast spin-echo (16 echo train, 4 acquisitions, 2 min 27 sec-3 min 16 sec). For all three pulse sequences, measurements were obtained of the signal intensities of normal marrow, abnormal marrow, fat, and noise posterior to the spine. Contrast-to-noise ratios were calculated for metastases in each case. Lesions were evaluated by three observers and rated for size, location, and conspicuity.RESULTSSignal intensities of fat, normal marrow, and noise were highest for T1-weighted fast spin-echo sequences. STIR fast spin-echo and fat-suppressed T2-weighted fast spin-echo had approximately similar fat-suppression capabilities. Though contrast-to-noise ratios were highest overall for STIR fast spin-echo, the finding was not statistically significant and lesion conspicuity was deemed better with fat-suppressed T2-weighted fast spin-echo and T1-weighted fast spin-echo images. Discrete lesions were well identified on all three pulse sequences.CONCLUSIONFast spin-echo sequences appear promising for the detection of vertebral metastases. Further work should be directed toward comparison with conventional spin-echo to determine whether fast spin-echo may replace conventional spin-echo sequences for evaluation of vertebral metastases.     

Comparison of Sagittal FSE T2, STIR,and T1-Weighted Phase-Sensitive Inversion Recovery in the Detection of Spinal Cord Lesions in MS at 3T

BACKGROUND AND PURPOSE:Determining the diagnostic accuracy of different MR sequences is essential to design MR imaging protocols. The purpose of the study was to compare 3T sagittal FSE T2, STIR, and T1-weighted phase-sensitive inversion recovery in the detection of spinal cord lesions in patients with suspected or definite MS.MATERIALS AND METHODS:We performed a retrospective analysis of 38 patients with suspected or definite MS. Involvement of the cervical and thoracic cord segments was recorded on sagittal FSE T2, STIR, and T1-weighted phase-sensitive inversion recovery sequences independently by 2 readers. A consensus criterion standard read was performed with all sequences available. Sensitivity, specificity, and interobserver agreement were calculated for each sequence.RESULTS:In the cervical cord, the sensitivity of T1-weighted phase-sensitive inversion recovery (96.2%) and STIR (89.6%) was significantly higher (P < .05) than that of FSE T2 (50.9%), but no significant difference was found between T1-weighted phase-sensitive inversion recovery and STIR. In the thoracic cord, sensitivity values were 93.8% for STIR, 71.9% for FSE T2, and 50.8% for T1-weighted phase-sensitive inversion recovery. Significant differences were found for all comparisons (P < .05). No differences were detected in specificity. Poor image quality and lower sensitivity of thoracic T1-weighted phase-sensitive inversion recovery compared with the other 2 sequences were associated with a thicker back fat pad.CONCLUSIONS:The use of an additional sagittal sequence other than FSE T2 significantly increases the detection of cervical and thoracic spinal cord lesions in patients with MS at 3T. In the cervical segment, both STIR and T1-weighted phase-sensitive inversion recovery offer high sensitivity and specificity, whereas in the thoracic spine, STIR performs better than T1-weighted phase-sensitive inversion recovery, particularly in patients with a thick dorsal fat pad.

MR imaging of the spinal cord is an important diagnostic technique in MS because the prevalence of spinal cord abnormalities in patients with clinically isolated syndrome is as high as 42%.¹ In clinically diagnosed MS, spinal cord involvement reaches 75%–92%, depending on the series.^2–4 The presence of asymptomatic cord lesions contributes to the demonstration of dissemination in space in the McDonald 2010 criteria for MS, and imaging of the spinal cord allows an increase of 18.3% in the number of patients meeting the diagnostic criteria.⁵ The presence of spinal cord lesions not only facilitates diagnosing MS but is also predictive of conversion to clinically definite MS, especially in patients with nonspinal clinically isolated syndrome who do not fulfill brain MR imaging criteria.⁶ Moreover, spinal cord lesions in MS can occur in isolation in 5% of patients, particularly in primary-progressive MS.⁷Spinal cord imaging is challenging because the spinal cord is a small and mobile structure.⁸ In addition, its anatomic location makes it prone to ghosting artifacts caused by the heart and great vessels as well as truncation artifacts. 3T MR imaging compared with 1.5T is more prone to artifacts caused by B₁ field inhomogeneity,⁹ susceptibility, vascular pulsation, and chemical shift.^10,11 In addition, 3T MR imaging has a higher energy deposit within the tissue, resulting in a higher specific absorption rate than lower field scanners. These problems can be partially solved with various technical adjustments and fast (parallel) imaging.¹²Traditionally, the spinal cord in patients with MS has been imaged by using sagittal and axial FSE T2/proton density sequences. Additional sequences, including STIR^13,14 and T1 inversion recovery,¹⁵ have shown promise by increasing lesion visibility, particularly at 3T, in which conventional FSE T2 and proton density images are frequently unsatisfactory.¹⁶ STIR has proved very useful as a complementary sequence in the detection of MS lesions but cannot be used in isolation due to its lower specificity.^13,14 Numerous studies have demonstrated the superiority of STIR over T2 at 1.5T,^{13,14,17–19} and 1 study¹⁵ also showed the advantages of STIR at 3T in the cervical cord. To our knowledge, no studies have been performed in the thoracic cord comparing sagittal FSE T2 and STIR. A recent publication showed the advantages of T1-weighted phase-sensitive inversion recovery (PSIR) for the detection of cervical spinal cord lesions in MS at 3T.¹⁶ PSIR has been shown to improve lesion localization and boundary definition over STIR in the cervical spinal cord, but it has not been tested in the thoracic cord.¹⁶The aim of our study was to compare the sensitivity and specificity of sagittal STIR, PSIR, and FSE T2 in the detection of MS spinal cord lesions at 3T, in both the cervical and thoracic segments.     

Retrospective Assessment of the Impact of Primary Language Video Instructions on Image Quality of Abdominal MRI

PurposeTo assess the impact of instructional videos in patients’ primary language on abdominal MR image quality for whom English is a second language (ESL).MethodsTwenty-nine ESL patients viewed Spanish or Mandarin Chinese instructional videos (approximately 2.5 min in duration) in the preparation room before abdominal MRI (ESL–video group). Comparison groups included 50 ESL patients who underwent MRI before video implementation (ESL–no video group) and 81 English-speaking patients who were matched for age, sex, magnet strength, and history of prior MRI with patients in the first two groups. Three radiologists independently assessed respiratory motion and image quality on turbo spin-echo T2-weighted images (T2WI) and postcontrast T1-weighted images (T1WI) using 1 to 5 Likert scales. Groups were compared using Kruskal-Wallis tests as well as generalized estimating equations (GEEs) to adjust for possible confounders.ResultsFor T2WI respiratory motion and T2WI overall image quality, Likert scores of the ESL–no video group (mean score across readers of 2.6 ± 0.1 and 2.6 ± 0.1) were lower (all P < .001) compared with English-speaking (3.3 ± 0.2 and 3.3 ± 0.1) and ESL–video (3.2 ± 0.1 and 3.0 ± 0.2) groups. In the GEE model, mean T2WI respiratory motion (both adjusted P < .001) and T2WI overall quality (adjusted P = .03 and .11) were higher in English and ESL–video groups compared with ESL–no video group. For T1WI respiratory motion and T1WI overall image quality, Likert scores were not different between groups (P > .05), including in the GEE model (adjusted P > .05).ConclusionProviding ESL patients with an instructional video in their primary language before abdominal MRI is an effective intervention to improve imaging quality.     

Free-breathing contrast-enhanced T1-weighted gradient-echo imaging with radial k-space sampling for paediatric abdominopelvic MRI

Objective

To compare the image quality of contrast-enhanced abdominopelvic 3D fat-suppressed T1-weighted gradient-echo imaging with radial and conventional Cartesian k-space acquisition schemes in paediatric patients.

Methods

Seventy-three consecutive paediatric patients were imaged at 1.5 T with sequential contrast-enhanced T1-weighted Cartesian (VIBE) and radial gradient echo (GRE) acquisition schemes with matching parameters when possible. Cartesian VIBE was acquired as a breath-hold or as free breathing in patients who could not suspend respiration, followed by free-breathing radial GRE in all patients. Two paediatric radiologists blinded to the acquisition schemes evaluated multiple parameters of image quality on a five-point scale, with higher score indicating a more optimal examination. Lesion presence or absence, conspicuity and edge sharpness were also evaluated. Mixed-model analysis of variance was performed to compare radial GRE and Cartesian VIBE.

Results

Radial GRE had significantly (all P?<?0.001) higher scores for overall image quality, hepatic edge sharpness, hepatic vessel clarity and respiratory motion robustness than Cartesian VIBE. More lesions were detected on radial GRE by both readers than on Cartesian VIBE, with significantly higher scores for lesion conspicuity and edge sharpness (all P?<?0.001).

Conclusion

Radial GRE has better image quality and lesion conspicuity than conventional Cartesian VIBE in paediatric patients undergoing contrast-enhanced abdominopelvic MRI.

Key Points

? Numerous techniques are required to provide optimal MR images in paediatric patients. ? Radial free-breathing contrast-enhanced acquisition demonstrated excellent image quality. ? Image quality and lesion conspicuity were better with radial than Cartesian acquisition. ? More lesions were detected on contrast-enhanced radial than on Cartesian acquisition. ? Radial GRE can be used for performing abdominopelvic MRI in paediatric patients.