The usefulness of the oblique coronal plane in knee MRI on the evaluation of the posterior cruciate ligament

Protruding anterior medial meniscus and posterior tibial translation as secondary signs of complete and partial posterior cruciate ligament tear

OBJECTIVE

To evaluate whether measurement of protruding anterior meniscus in the medial compartment (PAMM) and posterior tibial translation (PTT) can be used as a secondary sign of posterior cruciate ligament (PCL) tear for differential diagnosis of partial or complete tear.

METHODS

21 cases with complete PCL tear, 35 cases with partial PCL tear, and 55 normal cases were reviewed in this retrospective study. PTT and PAMM were measured from the MR images associated with each case. Non-parametric data were evaluated using the Kruskal-Wallis test and the Mann-Whitney U-test with Bonferroni correction to compare differences among the three groups: complete tear, partial tear, and controls.

RESULTS

There were significant differences in the median values of PAMM among the three groups, and with PAMM increasing as the grade of PCL injury increased. However, there were no significant differences in median PTT among the three groups. Median PAMM in the partial and complete tear groups was significantly higher than in subjects without PCL rupture (adjusted p-value <0.05). Although median PAMM in subjects in the complete tear group tended to be higher than in those with a partial tear, this difference was not statistically significant (adjusted p-values ≥0.418).

CONCLUSION

PAMM is more useful finding than PTT and can predict PCL tear with or without posterior instability. However, PAMM cannot differentiate partial tear and complete tear of the PCL.

ADVANCES IN KNOWLEDGE

PAMM is more useful finding than PTT and can predict PCL tear with or without posterior instability. However, PAMM cannot differentiate partial tear and complete tear of the PCL.

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.

Magnetic resonance imaging of the posterior cruciate ligament in flexion

BACKGROUND

Posterior cruciate ligament (PCL) injuries of the knee are common and sometimes difficult to diagnose. Magnetic resonance imaging (MRI), performed using standard orthogonal plane views, is the investigation of choice. It can be particularly difficult to differentiate acute partial and complete tears and identify elongation of chronic healed tears. The aim of the paper is to describe a new method of positioning the patient with the knee flexed at 90°, allowing the PCL to be visualised in a position of greatest length and tension which may assist in differentiating and identifying these injuries.

METHODS

Four symptomatic patients with suspected PCL injuries, two acute and two chronic, were MRI scanned using a routine protocol with the knee in extension before performing oblique sagittal fast spin-echo (FSE) proton-density (PD) sequences with the knee positioned in 90° of flexion. The appearance of the PCLs were then qualitatively assessed.

RESULTS

MRI scanning with the knee in flexion identified more extensive PCL injury than standard imaging. In the two patients with acute injuries, partial tears on the standard orthogonal plane views were found to be complete ruptures. In the two patients with chronic injuries, elongation of the PCL not identifiable on the standard orthogonal plane views was apparent.

CONCLUSION

MRI scanning of the PCL with the knee flexed at 90° may help in differentiating partial and complete ruptures of the PCL and identifying elongation of the PCL in chronic injuries.

Hyperextension injuries of the knee: do patterns of bone bruising predict soft tissue injury?

OBJECTIVE

To establish whether patterns of soft tissue injury following knee hyperextension are associated with post-traumatic 'bone bruise' distribution.

MATERIALS AND METHODS

Patients with a knee MRI within one year of hyperextension injury were identified at our institution over a 7 year period. MRIs, plain radiographs and clinical details of these patients were reviewed.

RESULTS

Twenty-five patients were identified (median time from injury to MRI = 24 days). The most common sites of bone bruising were the anteromedial tibial plateau (48%) and anterolateral tibial plateau (44%). There were high rates of injury to the posterior capsule (52%), ACL (40%) and PCL (40%) but lower rates of injury to the menisci (20%), medial and lateral collateral ligaments (16%) and posterolateral corner (16%). Anterior tibial plateau oedema and rupture of the posterior capsule predicted cruciate ligament injury [OR = 10.5 (p = 0.02) and 24.0 (p = 0.001) respectively]. Whilst anterolateral tibial plateau oedema strongly predicted PCL injury [OR = 26.0, p = 0.003], ACL injury was associated with a variable pattern of bone bruising. Meniscal injury was unrelated to the extent or pattern of bone bruising. 5 out of 8 patients with a 'double sulcus' on the lateral radiograph had ACL injury. The presence of a double sulcus showed significant association with anteromedial kissing contusions (OR = 7.8, p = 0.03).

CONCLUSIONS

Following knee hyperextension, bone bruising patterns may be associated with cruciate ligament injury. Other structures are injured less frequently and have weaker associations with bone bruise distribution. The double sulcus sign is a radiographic marker that confers a high probability of ACL injury.

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.

Principles and applications of the balanced steady-state free precession sequence in small animal low-field MRI

Magnetic resonance imaging (MRI) in small animal practice is largely based on classic two-dimensional spin-echo, inversion recovery and gradient-echo sequences which are largely limited by low spatial resolution, especially in low-field (LF)-MRI scanners. Nowadays, however, the availability of volumetric sequences can open new perspectives and enhance the diagnostic potential of this imaging modality. Balanced steady-state free precession (bSSFP) is a three-dimensional gradient-echo sequence in which image contrast is given by the ratio of T2 and T1, resulting in low soft-tissue signal, poor cerebral grey/white matter distinction and a bright signal from free fluid and fat. Such properties, along with a high signal-to-noise ratio and a very high spatial resolution deriving from acquisition of contiguous blocks of data, make this sequence perfectly suited for morphologic imaging, particularly for fluid-containing structures. Although bSSFP is widely adopted in human medical imaging, the use of this sequence in veterinary radiology is limited to anatomic studies of the inner ear and quadrigeminal cistern. This review aims to discuss the technical background of the bSSFP sequence and its possible advantageous applications in small animal LF-MRI for different specific disorders of the spine (arachnoid diverticula, small disc herniation, facet joint synovial cysts), brain (supracollicular fluid accumulation, traumatic injuries) and ligaments (complete and partial tears).

3D isotropic T2-weighted fast spin echo (VISTA) versus 2D T2-weighted fast spin echo in evaluation of the calcaneofibular ligament in the oblique coronal plane

AIM

To investigate whether the image quality of three-dimensional (3D) volume isotropic fast spin echo acquisition (VISTA) magnetic resonance imaging (MRI) of the calcaneofibular ligament (CFL) view is comparable to that of 2D fast spin echo T2-weighted images (2D T2 FSE) for the evaluation of the CFL, and whether 3D VISTA can replace 2D T2 FSE for the evaluation of CFL injuries.

MATERIALS AND METHODS

This retrospective study included 76 patients who underwent ankle MRI with CFL views of both 2D T2 FSE MRI and 3D VISTA. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of both techniques were measured. The anatomical identification score and diagnostic performances were evaluated by two readers independently. The diagnostic performances of 3D VISTA and 2D T2 FSE were analysed by sensitivity, specificity, and accuracy for diagnosing CFL injury with reference standards of surgically or clinically confirmed diagnoses. Surgical correlation was performed in 29% of the patients, and clinical examination was used in those who did not have surgery (71%).

RESULTS

The SNRs and CNRs of 3D VISTA were significantly higher than those of 2D T2 FSE. The anatomical identification scores on 3D VISTA were inferior to those on 2D T2 FSE, and the differences were statistically significant (p<0.05). There were no significant differences in diagnostic performance between the two sequences when diagnoses were classified as normal or abnormal.

CONCLUSION

Although the image quality of 3D VISTA MRI of the CFL view is not equal to that of 2D T2 FSE for the anatomical evaluation of CFL, 3D VISTA has a diagnostic performance comparable to that of 2D T2 FSE for the diagnosis of CFL injuries.

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.

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.

Usefulness of the oblique coronal plane in ankle MRI of the calcaneofibular ligament

AIM

To evaluate the usefulness and diagnostic accuracy of oblique coronal MRI of the calcaneofibular ligament (CFL) view for diagnosis of CFL injury.

MATERIAL AND METHODS

This retrospective study included 91 patients who were suspected to have CFL injury who underwent CFL view imaging. Anatomical identification of the CFL on orthogonal MRI sequences and CFL views was evaluated. Two radiologists evaluated the CFL based on an entire length view, an entire width view, and margin sharpness using a four-point scale. Diagnostic accuracy using orthogonal and CFL views was evaluated by calculating sensitivity, specificity, and accuracy. Arthroscopic or clinical findings were used as the reference standard.

RESULTS

Both readers found identification of lesions using the entire length, entire width, and sharp margin from CFL view images to be superior to that based on orthogonal images. The sensitivity and accuracy of diagnosing CFL injury were significantly higher when using the CFL view compared to the orthogonal view, although specificity was not significantly different between the CFL view and orthogonal view images.

CONCLUSIONS

CFL view imaging enables better anatomical evaluation and improved sensitivity and accuracy of diagnosis of CFL injury. CFL view images should therefore be used to evaluate potential CFL injuries.