Can isotropic fast gradient echo imaging be substituted for conventional T1 weighted sequences in shoulder MR arthrography at 3 Tesla?

PURPOSE: To assess the practical utility of isotropic shoulder imaging in patients undergoing MR arthrography. Isotropic shoulder imaging can be performed in less than three minutes with use of fast gradients. MATERIALS AND METHODS: Two experienced musculoskeletal radiologists retrospectively interpreted MR images of the shoulder in 100 consecutive patients undergoing MR arthrography of the shoulder. All patients underwent MRI of the shoulder in oblique coronal, oblique sagittal, and axial planes on a 3.0-Tesla MRI system. All patients had conventional fast spin-echo T1-weighted imaging. All patients also had thin section (0.4 mm) isotropic spoiled gradient echo images performed. A total of 67 of the 100 patients underwent subsequent arthroscopy and results were compared with MR interpretations. RESULTS: There were 41 full-thickness supraspinatus tendon tears, nine partial-thickness supraspinatus tendon tears (seven articular surface and two bursal surface), 21 superior labral, 18 anterior labral, and seven posterior labral tears demonstrated by consensus retrospective reading of the 100 shoulder MR exams. There was no difference in interpretation of the isotropic images as compared to the conventionally acquired images in the oblique coronal, oblique sagittal, and axial planes. Some patients had more than one finding on each exam. A total of 67 patients went on to arthroscopy. There were 41 full-thickness supraspinatus tendon tears, nine partial-thickness supraspinatus tendon tears, 21 superior labral, 18 anterior labral, and seven posterior labral tears demonstrated on arthroscopy. All full- and partial-thickness supraspinatus tendon tears seen at arthroscopy were seen on consensus MR reading. A total of 19 out of the 21 patients with superior labral anterior posterior (SLAP) tears at arthroscopy were seen on consensus MR reading. A total of 16 of the 18 anterior labral tears and six of the seven posterior labral tears seen at arthroscopy were seen on consensus MR reading. Some of the 67 patients had more than one finding on arthroscopy. CONCLUSION: Isotropic imaging of the shoulder is practical in clinical imaging when performed with use of fast gradients on a 3-Tesla system. Isotropic imaging provides the same clinical information as conventional imaging and can be acquired in less than three minutes.     

Lumbar intervertebral disc abnormalities: comparison of quantitative T2 mapping with conventional MR at 3.0?T

Objective  

To assess the relationship of morphologically defined lumbar disc abnormalities with quantitative T2 mapping.     

Comparing proton density and turbo spin echo T2 weighted static sequences with dynamic half-Fourier single-shot TSE pulse sequence at 3.0?T in diagnosis of temporomandibular joint disorders: a prospective study

Objectives:

The aim of this prospective study was to compare dynamic and static sequences in the evaluation of temporomandibular joint disorders using a 3.0 -T imaging unit.

Methods:

194 patients were evaluated by static (double echo proton density weighted/turbo spin echo T₂ weighted sequences) and dynamic (half-Fourier single-shot turbo spin echo sequences)imaging. Two radiologists evaluated in consensus the quality of images, the disc position and morphological alterations. The Kendall rank correlation coefficient (τ-b) was used to compare the qualitative rating between static and dynamic sequences. Cohen''s kappa coefficient (k) was used to assess the agreement of disc position and morphological alterations between both sequences. The intraclass correlation coefficient was used to calculate the intraobserver variability. The significance was set at p ≤ 0.05.

Results:

The correlation between both sequences in the qualitative evaluation was τ-b = 0.632. The agreement between both techniques in the evaluation of disc position was k = 0.856. The agreement between both techniques in assessing the morphological alterations was k = 0.487. In the static sequences, the intraclass correlation coefficient was 0.915 in the qualitative evaluation, 0.873 in the evaluation of disc position and 0.934 in the assessment of morphological alterations. In the dynamic sequences, the intraclass correlation coefficient was 0.785 in the qualitative evaluation, 0.935 in the evaluation of disc position and 0.826 in the assessment of morphological alterations.

Conclusions:

Static imaging remains the gold standard in the evaluation of the temporomandibular joint. Dynamic imaging is a valuable tool that can provide additional information about topographic changes in the disc–condyle relationship.     

Endometrial cancer: preoperative staging using three-dimensional T2-weighted turbo spin-echo and diffusion-weighted MR imaging at 3.0 T: a prospective comparative study

Objectives

To prospectively assess the efficacy of 3-T magnetic resonance (MR) imaging using the three-dimensional turbo spin-echo T2-weighted and diffusion-weighted technique (3D-TSE/DW) compared with that of conventional imaging using the two-dimensional turbo spin-echo T2-weighted and dynamic contrast-enhanced technique (2D-TSE/DCE) for the preoperative staging of endometrial cancer, with pathological analysis as the reference standard.

Methods

Seventy-one women with endometrial cancer underwent MR imaging using 3D-TSE/DW (b?=?1,000 s/mm²) and 2D-TSE/DCE. Two radiologists independently assessed the two imaging sets. Accuracy, sensitivity, and specificity for staging were analysed with the McNemar test; the areas under the receiver operating characteristic curve (Az) were compared with a univariate z-score test.

Results

The results for assessing deep myometrial invasion, accuracy, sensitivity, specificity and Az, respectively, were as follows: 3D-TSE/DW—observer 1, 87 %, 95 %, 85 % and 0.96; observer 2, 92 %, 84 %, 94 % and 0.95; 2D-TSE/DCE—observer 1, 80 %, 79 %, 81 % and 0.89; observer 2, 86 %, 84 %, 87 % and 0.86. Most of the values were higher with 3D-TSE/DW without significant differences (P?>?0.12). For assessing cervical stromal invasion, there were no significant differences in those values for both observers (P?>?0.6).

Conclusions

Accuracy of 3D-TSE/DW was at least equivalent to that of the conventional technique for the preoperative assessment of endometrial cancer.

Key Points

? New techniques in MR imaging help assess patients with endometrial cancer. ? A 3D T2-weighted TSE sequence seems equally as accurate as conventional techniques. ? Three-dimensional TSE/DW imaging does not require intravenous contrast material and is relatively quick. ? Tumour extent of endometrial cancer can be clearly shown on diffusion-weighted images. ? Junctional zone can be visualised well on 3D-TSE T2-weighted images.     

Isotropic 3D fast spin-echo imaging versus standard 2D imaging at 3.0 T of the knee—image quality and diagnostic performance

The objective of this study was to compare a newly developed fat-saturated intermediate-weighted (IM-w) 3D fast spin-echo (FSE) sequence with standard 2D IM-w FSE sequences regarding image quality and diagnostic performance in assessing abnormal findings of the knee. MR imaging was performed at 3.0 T in 50 patients. Images were assessed independently by three radiologists. Image quality was rated significantly higher (p < 0.05) for the 2D versus the 3D FSE sequences. Sensitivity for cartilage lesions was slightly higher for the 3D sequence, but specificity was lower. Low contrast objects were better visualized with 2D sequences, while high contrast objects were better shown with the 3D sequence. Confidence scores were higher for 2D than for 3D sequences, but differences were not significant. In conclusion, isotropic 3D FSE IM-w imaging may enhance standard knee MRI by increased visualization of high contrast lesions; however, 3D FSE image quality was lower.     

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.     

Chronic anterior cruciate ligament tears and associated meniscal and traumatic cartilage lesions: evaluation with morphological sequences at 3.0 T

Purpose  

To investigate the diagnostic efficacy of morphological sequences at 3.0 T MR imaging in detecting anterior cruciate ligament (ACL), meniscal pathology and traumatic cartilage legions in young patients with chronic deficient anterior cruciate ligament knees.     

Magnetic resonance cholangiopancreatography with GRASE sequence at 3.0T: does it improve image quality and acquisition time as compared with 3D TSE?

Objectives

The current study evaluated the clinical usefulness of the gradient and spin-echo (GRASE) sequence with single breath-hold in 3.0 T magnetic resonance cholangiopancreatography (MRCP). We compared the acquisition time and image quality between GRASE and breath navigator-triggered 3D turbo spin echo (3D TSE).

Methods

We examined 54 consecutive patients who underwent MRCP with GRASE and 3D TSE. We compared the image acquisition time and contrast-to-noise ratio (CNR) between the common bile duct (CBD) and liver. Overall image quality, blurring, motion artifacts and CBD visibility were scored on a 4-point scale by two radiologists. Paired t-tests were used to compare the variables.

Results

The mean image acquisition time was 95 % shorter with the GRASE than with 3D TSE (GRASE: 20 s; 3D TSE: 6 min 27 s). The CNR of GRASE was significantly higher than that of 3D TSE (GRASE: 25.4 ± 13.9 vs. 3D TSE: 18.2 ± 9.6, p < 0.01). All qualitative scores for GRASE were significantly better than those for 3D TSE.

Conclusions

3.0 T MRCP with GRASE sequence with single breath-hold significantly improved the CNR of CBD with a 95 % shorter acquisition time compared with conventional 3D MRCP with 3D TSE.

Key Points

? MRCP acquisition time was 95% shorter with GRASE than with 3D TSE.? Overall image quality of GRASE was significantly better than 3D TSE.? Pancreaticobiliary tree visibility with GRASE was better than that with 3D TSE.

     

Can a single isotropic 3D fast spin echo sequence replace three-plane standard proton density fat-saturated knee MRI at 1.5?T?

Objective:

To assess whether a single isotropic three-dimensional (3D) fast spin echo (FSE) proton density fat-saturated (PD FS) sequence reconstructed in three planes could replace the three PD (FS) sequences in our standard protocol at 1.5 T (Siemens Avanto, Erlangen, Germany).

Methods:

A 3D FSE PD water excitation sequence was included in the protocol for 95 consecutive patients referred for routine knee MRI. This was used to produce offline reconstructions in axial, sagittal and coronal planes. Two radiologists independently assessed each case twice, once using the standard MRI protocol and once replacing the standard PD (FS) sequences with reconstructions from the 3D data set. Following scoring, the observer reviewed the 3D data set and performed multiplanar reformats to see if this altered confidence. The menisci, ligaments and cartilage were assessed, and statistical analysis was performed using the standard sequence as the reference standard.

Results:

The reporting accuracy was as follows: medial meniscus (MM) = 90.9%, lateral meniscus (LM) = 93.7%, anterior cruciate ligament (ACL) = 98.9% and cartilage surfaces = 85.8%. Agreement among the readers was for the standard protocol: MM kappa = 0.91, LM = 0.89, ACL = 0.98 and cartilage = 0.84; and for the 3D protocol: MM = 0.86, LM = 0.77, ACL = 0.94 and cartilage = 0.64.

Conclusion:

A 3D PD FSE sequence reconstructed in three planes gives reduced accuracy and decreased concordance among readers compared with conventional sequences when evaluating the menisci and cartilage with a 1.5-T MRI scanner.

Advances in knowledge:

Using the existing 1.5-T MR systems, a 3D FSE sequence should not replace two-dimensional sequences.     

High-resolution depiction of the cranial nerves in the posterior fossa (N III–N XII) with 2D fast spin echo and 3D gradient echo sequences at 3.0 T

PurposeThe objective of this study was to evaluate the influence of high-resolution imaging obtainable with the higher field strength of 3.0 T on the visualization of the brain nerves in the posterior fossa by using T₂-weighted fast spin echo (FSE) and fast imaging employing steady-state gradient echo (GRE) sequences as the most suitable techniques to visualize each of the cranial nerves.Materials and methodsIn total, 20 nerves were investigated on MR images of 12 volunteers each and selected for comparison, respectively, with the FSE sequences with 5-mm and 2-mm section thicknesses and GRE sequences acquired with a 3.0-T scanner and a quadrature head coil. The resulting MR images were evaluated by three independent readers who rated image quality according to depiction of anatomic detail and contrast with use of a rating scale.ResultsIn general, decrease of the slice thickness showed a significant increase in the detection of nerves as well as in the image quality characteristics. As expected, artifacts were prominent in high-field imaging of the posterior fossa with GRE sequences. Nevertheless, comparing FSE and GRE imaging, the course of brain nerves and brainstem vessels was visualized best with use of the three-dimensional (3D) pulse sequence, although with respect to structural identification and contrast according to the rating scale, observer scores were not significantly improved.ConclusionThe comparison revealed the clear advantage of a thin section. The increased resolution enabled immediate identification of all brainstem nerves. Although image quality is impaired at GRE at high field strength, this sequence most distinctly and confidently depicted pertinent structures and enables 3D reconstruction in order to illustrate complex relations of the brainstem.     

Abdominal lymphoma staging: is MR imaging with T2-weighted turbo-spin-echo sequence a diagnostic alternative to contrast-enhanced spiral CT?

PURPOSE: To evaluate the diagnostic value of MR imaging in abdominal lymphoma staging, in comparison with that of the established spiral CT, within the context of a prospective study. METHODS: 50 patients with non-Hodgkin (n = 27) and Hodgkin lymphoma (n = 23) were examined with a plain T2-weighted TSE sequence (parameters: TE 90 ms, TR >2.500 ms, slice thickness 8 mm, slice interval 0.8 mm, ETL 20, NEX 4), and with spiral CT following oral and intravenous administration of contrast agent. RESULTS: Both CT and MR imaging agreed in showing abdominal lymphomas in 34/50 cases. The size of the detected lymphomas was between 1.5-9 cm (mean: 4.3 +/-2.2 cm). In the analysis of the individual lymph node sites, CT showed involvement of the paraaortic lymph nodes in 29/50 patients, compared with 28/50 in MRI, and involvement of the portal lymph nodes in 15/50, compared with 12/50. Both techniques showed the iliac lymph nodes in 21/50 patients, the inguinal lymph nodes in 10/50, and the mesenteric lymph nodes in 11/50. Both techniques also showed focal organ lesions in 12/50 cases. CONCLUSIONS: In the staging of abdominal lymphomas, MR imaging with a T2-weighted TSE sequence can be regarded as equal to spiral CT in the detection of lymph adenopathy and the demonstration of focal organ lesions. In addition to the absence of ionizing radiation, the advantage of MR imaging is that there is no necessity for oral or intravenous administration of contrast agent.     

High-resolution three-dimensional diffusion-weighted imaging of middle ear cholesteatoma at 3.0 T MRI: Usefulness of 3D turbo field-echo with diffusion-sensitized driven-equilibrium preparation (TFE–DSDE) compared to single-shot echo-planar imaging

Objective

To prospectively evaluate the usefulness of a newly developed high-resolution three-dimensional diffusion-weighted imaging method, turbo field-echo with diffusion-sensitized driven-equilibrium (TFE–DSDE) in diagnosing middle-ear cholesteatoma by comparing it to conventional single-shot echo-planar diffusion-weighted imaging (SS-EP DWI).

Materials and methods

Institutional review board approval and informed consent from all participants were obtained. We studied 30 patients with preoperatively suspected acquired cholesteatoma. Each patient underwent an MR examination including both SS-EP DWI and DSDE-TFE using a 3.0 T MR scanner. Images of the 30 patients (60 temporal bones including 30 with and 30 without cholesteatoma) were reviewed by two independent neuroradiologists. The confidence level for the presence of cholesteatoma was graded on a scale of 0–2 (0 = definite absence, 1 = equivocal, 2 = definite presence). Interobserver agreement as well as sensitivity, specificity, and accuracy for detection were assessed for the two reviewers.

Results

Excellent interobserver agreement was shown for TFE–DSDE (κ = 0.821) whereas fair agreement was obtained for SS-EP DWI (κ = 0.416). TFE–DSDE was associated with significantly higher sensitivity (83.3%) and accuracy (90.0%) compared to SS-EP DWI (sensitivity = 35.0%, accuracy = 66.7%; p < 0.05). No significant difference was found in specificity (96.7% for TFE–DSDE, 98.3% for SS-EP DWI)

Conclusion

With increased spatial resolution and reduced susceptibility artifacts, TFE–DSDE improves the accuracy in diagnosing acquired middle ear cholesteatomas compared to SS-EP DWI.     

Intracranial artery velocity measurement using 4D PC MRI at 3 T: comparison with transcranial ultrasound techniques and 2D PC MRI

Introduction

4D phase contrast MR imaging (4D PC MRI) has been introduced for spatiotemporal evaluation of intracranial hemodynamics in various cerebrovascular diseases. However, it still lacks validation with standards of reference. Our goal was to compare blood flow quantification derived from 4D PC MRI with transcranial ultrasound and 2D PC MRI.

Methods

Velocity measurements within large intracranial arteries [internal carotid artery (ICA), basilar artery (BA), and middle cerebral artery (MCA)] were obtained in 20 young healthy volunteers with 4D and 2D PC MRI, transcranial Doppler sonography (TCD), and transcranial color-coded duplex sonography (TCCD). Maximum velocities at peak systole (PSV) and end diastole (EDV) were compared using regression analysis and Bland–Altman plots.

Results

Correlation of 4D PC MRI measured velocities was higher in comparison with TCD (r?=?0.49–0.66) than with TCCD (0.35–0.44) and 2D PC MRI (0.52–0.60). In mid-BA and ICA C7 segment, a significant correlation was found with TCD (0.68–0.81 and 0.65–0.71, respectively). No significant correlation was found in carotid siphon. On average over all volunteers, PSVs and EDVs in MCA were minimally underestimated compared with TCD/TCCD. Minimal overestimation of velocities was found compared to TCD in mid-BA and ICA C7 segment.

Conclusion

4D PC MRI appears as valid alternative for intracranial velocity measurement consistent with previous reference standards, foremost with TCD. Spatiotemporal averaging effects might contribute to vessel size-dependent mild underestimation of velocities in smaller (MCA), and overestimation in larger-sized (BA and ICA) arteries, respectively. Complete spatiotemporal flow analysis may be advantageous in anatomically complex regions (e.g. carotid siphon) relative to restrictions of ultrasound techniques.     

Endorectal 3D T2-weighted 1 mm-slice thickness MRI for prostate cancer staging at 1.5 Tesla: Should we reconsider the indirects signs of extracapsular extension according to the D’Amico tumor risk criteria?

Purpose

To evaluate the accuracy of a 3D-endorectal 1 mm-thick slices MRI acquisition for local staging of low, intermediate and high D’Amico risk prostate cancer (PCa).

Materials and methods

178 consecutive patients underwent a multiparametric MRI protocol prior to radical prostatectomy (RP). T2W images were acquired with the 3D sampling perfection with application optimized contrasts using different flip angle evolutions (SPACE) sequence (5 mn acquisition time). Direct and indirect MRI signs of extracapsular extension (ECE) were evaluated to predict the pT stage. The likelihood of SVI (seminal vesicle invasion) was also assessed.

Results

Histology showed ECE and SVI in 38 (21%) and 12 (7%) cases, respectively. MRI sensitivity and specificity to detect ECE were 55 and 96% if direct signs of ECE were used and 84 and 89% (p < 0.05), if both direct and indirect signs were combined. D’Amico criteria did not influence MRI performance. Sensitivity and specificity for SVI detection were 83% and 99%.

Conclusions

3D data sets acquired with the SPACE sequence provides a high accuracy for local staging of prostate cancer. The use of indirect signs of ECE may be recommended in low D’Amico risk tumors to optimise patient selection for active surveillance or focal therapy.