Three-dimensional isotropic T2-weighted fast spin-echo (VISTA) knee MRI at 3.0 T in the evaluation of the anterior cruciate ligament injury with additional views: comparison with two-dimensional fast spin-echo T2-weighted sequences

Assessment of the Usefulness of Image Reconstruction in the Oblique and Double-oblique Sagittal Planes for Magnetic Resonance Imaging of the Canine Cranial Cruciate Ligament

Introduction

The aim of the study was to determine the quality and significance of the magnetic resonance image of the canine knee after reconstruction in the oblique and double-oblique sagittal plane. This reconstruction and 3D images are rarely used in common protocols due to the longer study time they require. The study aimed to demonstrate significance for such diagnostic images in specific sequences in order to stimulate consideration of their more frequent use in diagnosis of diseases of the cruciate ligament in dogs.

Material and Methods

All tests were carried out using an open magnetic resonance tomography scanner with magnetic field induction. The images obtained from the 30 canine patients examined were reconstructed and evaluated by independent appraisers. Statistical analysis was performed.

Results

The study showed that MRI of the stifle joint using 3D sequences provides higher quality images of the cranial cruciate ligament in dogs. The results of the statistical analysis showed that multi-faceted reconstruction allows the secondary determination of the oblique imaging planes and obtains images of adequate quality.

Conclusion

It can be concluded that multi-faceted reconstruction facilitates the secondary determination of oblique imaging planes. This reconstruction additionally makes images available of better quality compared to the 2D sequence.

Evaluation of the anterior inferior tibiofibular and anterior talofibular ligaments using 2D oblique coronal imaging and 3D isotropic resolution T2-weighted fast spin-echo sequences at 3.0 T: Is there additional diagnostic value?

INTRODUCTION

To compare diagnostic performance of additional two-dimensional (2D) oblique coronal view and three-dimensional (3D) T2-weighted fast spin-echo(FSE) images for diagnosing injury of the anterior inferior tibiofibular (AiTFL) and anterior talofibular ligaments (ATFL).

METHODS

This study included 48 patients with ankle sprain who had undergone MRI using standard protocol and two additional sequences with 2D oblique coronal and 3D isotropic images, followed by arthroscopic surgery. Ligament injuries was subdivided by intact tendon, partial or complete tear. Retrospectively, two musculoskeletal radiologists respectively reviewed three image sets of MR including 2D axial image only (set 1), 2D axial and oblique coronal images (set 2), and 2D axial with 3D-isotropic images (set 3). Using arthroscopic findings as reference standard, diagnostic performances of both methods were analysed by the area under the curve (AUC).

RESULTS

Arthroscopy confirmed 13 AiTFL and 41 ATFL injuries. For AiTFL, when set 1 and set 3 were compared, AUC value was significantly higher for set 3 (P < 0.05). However, there was no significant difference between AUC values for set 2 and set 3 sequences by either reader for either type of tear (P > 0.05). For ATFL, both readers found there was no significant difference in AUC values between set 1 and set 3 and between set 2 and set 3.

CONCLUSION

Additional oblique coronal sequence demonstrated better diagnostic performance for AiTFL injury than conventional and isotropic imaging did. This sequence showed as much diagnostic accuracy as isotropic sequence for evaluation of ATFL injury.

The usefulness of the oblique coronal plane of three-dimensional isotropic T2-weighted fast spin-echo (VISTA) knee MRI in the evaluation of posterior cruciate ligament reconstruction with allograft: Comparison with the oblique coronal plane of two-dimensional fast spin-echo T2-weighted sequences

PURPOSE

We compared two imaging techniques to assess whether 3D VISTA imaging could replace 2D FSE in diagnosing PCL reconstruction complications.

MATERIALS AND METHODS

This retrospective study included 40 patients who underwent surgery of PCL reconstruction and follow-up knee MRI (3D VISTA and 2D FSE) for evaluation of PCL graft integrity. Each image was interpreted independently by two radiologists without knowledge of radiologic reports or clinical history. The diagnostic performance of the 2D FSE PCL view, 3D VISTA PCL view, orthogonal 2D FSE image, and combined sequences were evaluated in terms of sensitivity, specificity, and accuracy for diagnosing complications of PCL graft. The reference diagnoses were made arthroscopically or clinically.

RESULTS

The sensitivities of the 3D VISTA PCL view were similar to those of the 2D PCL view. The sensitivities of the combination of the orthogonal view and the 3D VISTA PCL view were also similar to those of the combination of the orthogonal view and the 2D PCL view. The specificities and accuracies of each image exhibited similar results. There was no statistically significant difference in diagnostic performance between the 3D VISTA PCL view and the 2D PCL view (solitary or combined with the orthogonal view).

CONCLUSIONS

The diagnostic performance of the PCL views on 3D VISTA images is comparable to that of 2D FSE images in the diagnosis of PCL graft complications.

The rotating stretched curved planar reconstruction of 3D-FIESTA MR imaging for evaluating the anterior cruciate ligament of the knee joint

PURPOSE

To determine the feasibility of the rotating stretched curved planar reconstruction (CPR) of three-dimensional fast imaging with steady-state acquisition magnetic resonance imaging (3D-FIESTA MRI) for evaluating the anterior cruciate ligament of the knee joint.

MATERIALS AND METHODS

MRI of 40 knee joints in healthy volunteers was performed on a 3.0-T MR scanner and a phased-array extremity coil. The protocol consisted of oblique sagittal spin echo (SE) T1WI, coronal FS-PDWI, axial FS-FSE-T2WI, and 3D-FIESTA sequences. The rotating stretched curved planar reconstructions (CPR) of the ACL at angles of 0°, 30°, 60°, 90°, 120°, 150°, and 180° were generated from images of 3D-FIESTA sequences. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the 3D-FIESTA were compared with those of the oblique sagittal SE T1WI sequence. The presence of the tibial attachment, midportion, femoral attachment, and double bundles of the ACL on the oblique sagittal SE T1WI and CPR of 3D-FIESTA MR imaging were divided into two categories: visible and not visible.

RESULTS

The ACL SNR efficiency of 3D-FIESTA sequences was significantly higher than that of oblique sagittal SE T1WI sequence (P < 0.05). The 3D-FIESTA sequences produced images with a significantly higher CNR between ACL and synovial fluid than did the oblique sagittal SE T1WI sequence (P < 0.05). CPR of 3D-FIESTA MRI generated an excellent visualization of the ACL. The CPR of 3D-FIESTA MRI was rated superior to oblique sagittal SE T1WI sequence in 60% and 65% of cases with regard to the tibial attachment and midportion of ACL, respectively (P < 0.05). CPR of 3D-FIESTA MR imaging was rated superior to oblique sagittal SE T1WI sequence in 80% and 85% of cases with regard to femoral attachment and double bundles of ACL, respectively (P < 0.05).

CONCLUSION

The rotating stretched curved planar reconstruction of 3D-FIESTA sequences is significantly better than that of conventional 2D-MRI in evaluating the native ACL and its components, AM bundle and PL bundle, in healthy volunteers.

Feasibility of synthetic MRI in knee imaging in routine practice

Background

Synthetic magnetic resonance (MR) is a method allowing reduction of examination time and access to quantitative imaging.

Purpose

This study sought to assess the image quality and diagnostic accuracy of synthetic magnetic resonance imaging (MRI) compared to standard MRI in patients with knee pain.

Material and Methods

In total, 22 patients underwent standard 1.5 knee MRI with an added synthetic sequence. Quantitative T1, T2, and proton density (PD) images were generated synthetically; T1, PD, and short tau inversion recovery (STIR) weighted images were created with chosen echo time (TE), repetition time (TR), and inversion time (TI). Two blinded musculoskeletal radiologists evaluated the overall sequence quality, visualization of anatomic structures, and presence of artifacts using a 3-point score.

Results

The synthetic sequence was acquired in 39% less time than the conventional MRI. Synthetic PD, T1, and STIR images were rated fair (2%, 5%, and 2%, respectively) or good quality (98%, 95%, and 98%, respectively), despite the presence of popliteal artery artifacts. Cartilage and meniscus were well visualized in all cases. Anterior cruciate ligament visualization was rated poor in 7%, 14%, and 30% of PD, STIR, and T1 images, respectively.

Conclusion

Our pilot study confirmed the feasibility of synthetic MRI in knee examinations, proving faster and achieving appropriate quality and good diagnostic confidence.

Preoperative magnetic resonance imaging predicts eligibility for arthroscopic primary anterior cruciate ligament repair

PURPOSE

To assess the role of preoperative magnetic resonance imaging (MRI) on the eligibility for arthroscopic primary anterior cruciate ligament (ACL) repair.

METHODS

All patients undergoing ACL surgery between 2008 and 2017 were included. Patients underwent arthroscopic primary repair if sufficient tissue length and quality were present, or they underwent single-bundle ACL reconstruction. Preoperative MRI tear locations were graded with the modified Sherman classification: type I (>90% distal remnant length), type II (75-90%), or type III (25-75%). MRI tissue quality was graded as good, fair, or poor. Arthroscopy videos were reviewed for tissue length and quality, and final treatment.

RESULTS

Sixty-three repair patients and 67 reconstruction patients were included. Repair patients had more often type I tears (41 vs. 4%, p < 0.001) and good tissue quality (89 vs. 12%, p < 0.001). Preoperative MRI tear location and tissue quality predicted eligibility for primary repair: 90% of all type I tears and 88% of type II tears with good tissue quality were repaired, while only 23% of type II tears with fair tissue quality, 0% of type II tears with poor tissue quality, and 14% of all type III tears could be repaired.

CONCLUSIONS

This study showed that tear location and tissue quality on preoperative MRI can predict eligibility for arthroscopic primary ACL repair. These findings may guide the orthopaedic surgeon on the preoperative assessment for arthroscopic primary repair of proximal ACL tears.

LEVEL OF EVIDENCE

Level IV.

Comparison of two-dimensional fast spin echo T2 weighted sequences and three-dimensional volume isotropic T2 weighted fast spin echo (VISTA) MRI in the evaluation of triangular fibrocartilage of the wrist

OBJECTIVE

To compare image quality of three-dimensional volume isotropic T₂ weighted fast spin echo (3D VISTA) and two-dimensional (2D) T₂ weighted images (T2WI) for evaluation of triangular fibrocartilage (TFC) and to investigate whether 3D VISTA can replace 2D T₂ WI in evaluating TFC injury.

METHODS

This retrospective study included 69 patients who received wrist MRIs using both 2D T₂ WI and 3D VISTA techniques for assessment of wrist pathology, including TFC injury. Two radiologists measured the signal-to-noise ratio (SNR) and the contrast-to-noise ratio (CNR) of the two sequences. The anatomical identification score and diagnostic performance were independently assessed by two interpreters. The diagnostic abilities of 3D VISTA and 2D T₂ WI were analysed by sensitivity, specificity and accuracy for diagnosing TFC injury using surgically or clinically confirmed diagnostic reference standards.

RESULTS

17 cases (25%) were classified as having TFC injury. 2 cases (12%) were diagnosed surgically, and 15 cases (88%) were diagnosed by physical examination. 52 cases (75%) were diagnosed as having intact TFC. 8 of these cases (15%) were surgically confirmed, while the others were diagnosed by physical examination and clinical findings. The 3D VISTA images had significantly higher SNR and CNR values for the TFC than 2D T₂ WI images. The scores of 3D VISTA's total length, full width and sharpness were similar to those of 2D T₂ WI. We were unable to find a significant difference between 3D VISTA and 2D T₂ WI in the ability to diagnose TFC injury.

CONCLUSION

3D VISTA image quality is similar to that of 2D T₂ WI for TFC evaluation and is also excellent for tissue contrast. 3D VISTA can replace 2D images in TFC injury assessment. Advances in knowledge: 3D VISTA image quality is similar to that of 2D T₂ WI for TFC evaluation and is also excellent for tissue contrast. 3D VISTA can replace 2D images in TFC injury assessment.

The Bow Tie Shape of the Anterior Cruciate Ligament as Visualized by High-Resolution Magnetic Resonance Imaging

BACKGROUND

Although numerous studies have examined the anatomic characteristics of the anterior cruciate ligament (ACL), its actual shape remains unclear.

PURPOSE

To determine the average shape of the ACL by analyzing its cross section through the use of high-resolution magnetic resonance imaging (MRI) data.

STUDY DESIGN

Descriptive laboratory study.

METHODS

The study included 96 MRIs, conducted using a 3.0-T magnet, to analyze the shape of the ACL. Three-dimensional, curved multiplanar reconstruction was used to obtain cross sections at 7 points (femoral insertion; midsubstance 1, 2, 3, 4, and 5 from the femoral side to the tibial side; and tibial insertion). The width and thickness of cross sections were measured by 2 independent observers, and the ratio of width to thickness was calculated to determine the proportions of each cross section. The 7 cross sections were accumulated and standardized to generate an average model through the use of image analysis software developed by the authors.

RESULTS

The mean ± SD width (femoral insertion, 17.02 ± 2.17 mm; tibial insertion, 17.33 ± 2.03 mm) and thickness (femoral insertion, 11.03 ± 1.75 mm; tibial insertion, 10.09 ± 1.70 mm) of both insertions were significantly larger than those of midsubstance 4 (width, 9.99 ± 1.87 mm; thickness, 6.53 ± 1.25 mm) ( P < .001). The mean ratios of width to thickness of the 7 cross sections from femoral insertion to tibial insertion were 1.57 ± 0.23, 3.36 ± 0.57, 3.07 ± 0.81, 2.18 ± 0.54, 1.56 ± 0.32, 2.16 ± 0.48, and 1.75 ± 0.28, respectively. The shape of the cross section at midsubstance 4 was an oval isthmus, which was the most narrow and well-balanced shape. It was transformed into a wide band at midsubstance 1 and 5. The shape of the femoral insertion was semicircular, with its anterior side slightly straight and its posterior side convex. The tibial insertion was kidney bean-shaped.

CONCLUSION

On 3.0-T MRI, the ACL has a "bow tie" shape, including an oval isthmus, with a semicircular femoral insertion and kidney bean-shaped tibial insertion.

CLINICAL RELEVANCE

The measurement method will allow surgeons to quantitatively diagnose partial injuries of the ACL using a noninvasive system in actual patients.

Advanced MRI Techniques for the Ankle

OBJECTIVE

The purposes of this article are to present a state-of-the-art routine protocol for MRI of the ankle, to provide problem-solving tools based on specific clinical indications, and to introduce principles for the implementation of ultrashort echo time MRI of the ankle, including morphologic and quantitative assessment.

CONCLUSION

Ankle injury is common among both athletes and the general population, and MRI is the established noninvasive means of evaluation. The design of an ankle protocol depends on various factors. Higher magnetic field improves signal-to-noise ratio but increases metal artifact. Specialized imaging planes are useful but prolong acquisition times. MR neurography is useful, but metal reduction techniques are needed whenever a metal prosthesis is present. An ultrashort echo time sequence is a valuable tool for both structural and quantitative evaluation.

Comparison of oblique coronal images in knee of three-dimensional isotropic T2-weighted turbo spin echo MRI versus two-dimensional fast spin echo T2-weighted sequences for evaluation of posterior cruciate ligament injury

OBJECTIVE

To compare image quality between three-dimensional volume isotropic turbo spin echo acquisition (3D VISTA) with the posterior cruciate ligament (PCL) view and two-dimensional (2D) fast spin echo (FSE) for evaluation of PCL injury.

METHODS

This retrospective study included 60 patients with clinical suspicion of PCL injury who underwent both 2D FSE and 3D VISTA of the knee between January 2015 and December 2015. The diagnostic performance of each oblique coronal view and the combined images was evaluated for sensitivity, specificity and accuracy for diagnosing a PCL tear. The arthroscopically confirmed diagnoses were used as the reference standard. Data were analyzed using the McNemar test.

RESULTS

The mean contrast-to-noise ratio was significantly higher for 3D VISTA than for 2D FSE. The two imaging modalities did not differ significantly in anatomical identification ability, with the exception of margin sharpness, which was inferior for 3D VISTA with Reader 2 (p = 0.038). When we classified the diagnoses of PCL injury as normal or abnormal, there were no significant differences in sensitivity, specificity or accuracy between the PCL view of 3D VISTA and 2D FSE images (p > 0.05).

CONCLUSION

3D VISTA had a superior contrast-to-noise ratio than 2D FSE and similar image quality in the evaluation of the PCL. The PCL view of 3D VISTA has the same diagnostic ability as 2D FSE in the diagnosis of PCL injury and can thus replace 2D FSE. Advances in knowledge: The oblique coronal view 3D VISTA MRI has similar diagnostic ability to 2D FSE in the diagnosis of PCL injury, and therefore 3D VISTA image can replace 2D FSE.

Usefulness of oblique coronal magnetic resonance images of the knee after posterior cruciate ligament reconstruction

OBJECTIVE:

To know the usefulness of the oblique coronal view of the posterior cruciate ligament (PCL) in the evaluation of the graft normal anatomy and the diagnostic accuracy of combining the PCL view with orthogonal views for the evaluation of PCL graft failure or impingement after reconstruction procedures.

METHODS:

This retrospective study included 54 patients who underwent PCL-view MRI after PCL reconstruction surgery. Anatomic identification of graft failure and impingement was scored by two radiologists. The ability to diagnose PCL graft failure with the PCL view, orthogonal view or combined PCL/orthogonal views was evaluated by calculating the sensitivity, specificity and accuracy.

RESULTS:

The entire width discrimination scores and margin sharpness scores for the PCL view were significantly higher than those for the orthogonal view for both readers. The specificities and accuracies for the PCL view and the combined PCL/orthogonal views were higher than those for the orthogonal view alone, but these differences were not statistically significant.

CONCLUSION:

The PCL view provided a better anatomic evaluation than the orthogonal view with regard to the entire width evaluation and margin sharpness evaluation of the PCL graft. The combined view of orthogonal and PCL views was slightly more sensitive and accurate, but not significantly so, in the diagnoses of graft failure and impingement.

ADVANCES IN KNOWLEDGE:

The PCL view provided a better anatomic evaluation than the orthogonal view with regard to the entire width evaluation and margin sharpness evaluation of the PCL graft. The PCL view was slightly more sensitive and accurate, but not significantly so, in the diagnoses of graft failure and impingement.

Comparison of two MR grading systems for correlation between grade of cervical neural foraminal stenosis and clinical manifestations

OBJECTIVE

To compare the reliability of two recently reported MR grading systems of cervical neural foraminal stenosis (CNFS) and their correlation with clinical manifestations.

METHODS

We evaluated 188 patients (male : female = 80 : 108; mean age of 41 years) who visited our institution and underwent oblique sagittal MRI of the cervical spine. Two radiologists evaluated the MRI findings for the presence and grade of CNFS at the narrowest point, with the grading systems (Park, Kim and mKim systems) suggested by Park et al and Kim et al. More than one positive neurologic sign and more than one neurologic clinical symptom was considered a positive neurologic manifestation of each foraminal stenosis. Interobserver agreement between the two readers was analyzed using kappa statistics. Non-parametric correlation analysis (Spearman's correlation) was used to evaluate the correlation coefficients (R) to assess the relationship between CNFS grade and clinical manifestations.

RESULTS

Both the Park and mKim systems demonstrated a relatively high correlation (R = 0.714-0.764) between the CNFS grade and clinical manifestation, while the Kim system yielded a moderate correlation (by Reader 2). The Park and mKim systems demonstrated higher correlation values at the level of C6-7 than C4-5, while the Kim system showed no difference in correlation at the cervical spine level.

CONCLUSION

Both the Park and mKim systems provide a reliable, reproducible CNFS diagnosis, while the Kim system has a slightly inferior reliability. The Park and mKim systems had a similar, relatively high clinical correlation.

ADVANCES IN KNOWLEDGE

Grades 2 and 3 of the Park system and Grade 2 in the Kim and mKim systems exhibited a similar clinical significance. Patients with a grade of 0 (using each system) consistently exhibit negative neurologic manifestation.

Three-dimensional isotropic T2-weighted fast spin-echo (VISTA) ankle MRI versus two-dimensional fast spin-echo T2-weighted sequences for the evaluation of anterior talofibular ligament injury

AIM

To compare the performance of axial images of the ankle joint on three-dimensional (3D) volume isotropic turbo spin echo acquisition (VISTA) with that of two-dimensional (2D) fast spin echo (FSE) T2-weighted images for the diagnosis of anterior talofibular ligament (ATFL) injury.

MATERIALS AND METHODS

This retrospective study included 101 patients who underwent both 2D FSE T2-weighted and 3D VISTA magnetic resonance imaging (MRI) of the ankle. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of both sequences were measured. The anatomical identification score and diagnostic performances of both sequences were evaluated by two radiologists. The diagnostic performances of 3D VISTA and 2D FSE images were analysed in terms of sensitivity, specificity, and accuracy for diagnosing ATFL injury. Surgically or clinically confirmed diagnoses were used as reference standards.

RESULTS

The margin sharpness scores on 3D VISTA were significantly inferior to those of 2D FSE (p<0.001). Other scores (entire length, entire width) were not significantly different between the two imaging methods. The SNRs and CNRs of 3D VISTA were significantly higher than those of 2D FSE (p<0.001). When diagnoses were classified as normal and abnormal, the specificity of the 3D VISTA images for the diagnosis of ATFL injury was 95.7%, significantly superior to 2D FSE (84.3-85.7%). There were no significant differences between 3D VISTA and 2D FSE images in sensitivity or accuracy for diagnosis (p=0.227-1.000), with the exception of accuracy by reader 1 (p=0.039).

CONCLUSION

3D VISTA imaging has a diagnostic performance comparable to that of 2D FSE for the diagnosis of ATFL injury, although 3D VISTA is inferior to 2D FSE for the evaluation of margin sharpness. Replacing axial and coronal images with 3D VISTA can save imaging time without negatively impacting the diagnostic ability for ATFL injury.

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.