3T MRI of wrist ligaments and TFCC using true plane oblique 3D T2 Dual Echo Steady State (DESS) – a study of diagnostic accuracy

Abstract

Objective:

This study was designed to assess the accuracy of unenhanced 3T MRI supplemented with dedicated true plane reformats of 3D T2 Dual Echo Steady State (DESS), in assessing tears of scapholunate, lunotriquetral ligaments and triangular fibrocartilage complex, using arthroscopy as gold-standard.

Methods:

In a retrospective cohort review, patients who underwent wrist arthroscopy and MRI over 2 years (n=46) were identified. Dedicated axial and coronal reformats were obtained from 3D T2 DESS sequence for assessing intrinsic ligaments and triangular fibrocartilage (TFCC). At arthroscopy, tears were classified using Geissler’s classification and compared to MRI findings.

Results:

The sensitivity of unenhanced 3T MRI in detecting scapholunate ligament tears was 87%, specificity was 90% and negative predictive value of 93%. The lunate triquetral ligament was assessed with a high specificity (97%) and negative predictive value (93%), sensitivity was 63%. TFCC tears were assessed with a sensitivity of 100%. The overall diagnostic accuracy of unenhanced 3T MRI of wrist in detecting ligament tears was 91%.

Conclusion:

3T wrist MRI with dedicated reformats from 3D T2 DESS has a high diagnostic accuracy in assessing acute intrinsic ligament and TFCC injuries. High strength 3T MRI with good technical quality isotropic 3D T2 DESS is critical for accurate wrist ligament assessment. Negative predictive values of 3T MRI of 95% can lead to reduced need for diagnostic arthroscopy of the wrist.

Advances in knowledge:

This study assesses the diagnostic performance of unenhanced 3T MRI with 3D T2 DESS in assessing traumatic wrist ligament tears. The accuracy of T2 DESS in wrist imaging has not been previously reported.

Introduction

MRI technology has improved in recent years, with greater availability of high strength 3 T magnets in clinical practice and improved dedicated extremity coils.¹ Direct visualization and assessment of intrinsic wrist ligaments is possible following wrist trauma, when patients are offered MRI due to concern of a scaphoid fracture not detected on initial radiographs or suspicion of wrist ligament/triangular fibrocartilage complex (TFCC) tears due to positive clinical provocation tests.² Acute traumatic intrinsic ligament tears can result in dissociative carpal instability due to scapholunate or lunotriquetral dissociation.³ These can occur following significant injuries like road traffic collisions resulting in complete ligament tears or subacute repetitive sprains of carpal ligaments due to work or sporting activity.

Use of dedicated wrist coils and high field strength MRI allows assessment of wrist ligaments for injury by demonstrating structural change like edema or full thickness tear, as opposed to indirect assessment on radiographs by signs like widening of scapholunate interval and lunate tilt which may not be apparent initially following trauma. There is also some evidence to suggest improved outcomes of primary repair of scapholunate ligament injuries with or without dorsal capsulodesis within 6 weeks of injury.⁴

There have been studies reporting variable diagnostic performance of MRI (1.5 T and 3 T) in assessment of wrist ligaments.^5,6 In the present study, we evaluate the accuracy of unenhanced 3 T MRI with axial oblique reformats from 3D T2 Dual Echo Steady State (DESS) sequence for assessing scapholunate and lunotriquetral ligaments and coronal/sagittal oblique reformats for TFCC, using arthroscopy as gold-standard.⁷ DESS is a 3D coherent (steady state) GRE sequence (Siemens) providing high resolution heavily T₂* weighted images which can be reconstructed in any plane using a standard picture archiving and communication system (PACS) electronic multiplanar reconstruction (MPR) tool. This sequence has been used for cartilage imaging in the knee; its diagnostic performance in wrist ligament imaging has not previously been reported.⁸

Methods and materials

In a retrospective cohort review, consecutive patients who underwent wrist arthroscopy over 2 years (2017–2019; n = 56) were identified from the arthroscopy database of a large teaching hospital with a dedicated Hand Unit. Patients who had a wrist MRI prior to wrist arthroscopy were included. The clinical symptoms included wrist pain and/or reduced grip strength following recent or past trauma. A total of 10 patients who did not have MRI scans on the local PACS were excluded. Mean age of 46 patients studied was 37.6 years (SD-12 years). The right wrist was assessed in 30 patients and left wrist in 16. Data collected included demographics, date of MRI and arthroscopy, MRI and arthroscopy findings, as well as time interval between MRI and arthroscopy. MRI was performed on a Siemens 3 T Verio using a dedicated wrist coil, comprising of three sequences in coronal plane - spin echo T1, fat saturated proton density, 3D T2DESS (repetition time-13.8, echo time-5.2, flip angle 30 degrees, field of view 100 mm, resolution 256 × 100, 112 slices/slab, time for sequence – 3 min) and axial T2 fat saturated sequences. Sagittal reformats for the wrist were obtained from 3d T2 DESS sequence for all studies. MRI studies were assessed by two Consultant Musculoskeletal Radiologists and recorded in consensus, blinded to arthroscopic findings (*anonimised). The proximal carpal row intrinsic ligaments (scapholunate and lunotriquetral) were assessed in two planes – true axial oblique reformats, obtained for both ligaments, were used to assess the dorsal and volar components and coronal plane to assess membranous component on the 3D T2DESS sequence. Dedicated true plane axial reformats were obtained from the 3D T2 DESS sequence using a standard MPR tool on PACS (Carestream, Philips) (figFigures 1, 2a and b, 3a and b).

Figure 1.

Consecutive axial oblique reformats from Coronal 3D T2 DESS MRI demonstrate intact dorsal (solid arrows), volar (dashed arrows) and membranous components (star) of the scapholunate ligament. Series of three images proximal to distal (top to bottom). Image insert top left corner with red line indicating plane of MP reconstruction. DESS, Dual Echo Steady State; MP, multiplanar.

Figure 2.

Consecutive axial oblique reformats (2a) from Coronal 3D T2 DESS MRI demonstrate intact dorsal (solid arrows), volar (dashed arrows) and membranous components (star) of the lunatetriquetral ligament. Series of three images proximal to distal (top to bottom). Coronal T2 DESS image shows the membranous component of the lunate triquetral ligament (2b, arrow). Image insert top left corner with red line indicating plane of MP reconstruction. DESS, Dual Echo Steady State; MP, multiplanar.

Figure 3.

Normal TFC on coronal oblique reformats of 3D T2 DESS showing foveal (a) and styloid tip (b) attachment of TFC. Insert images at top left corner of figure 6a with red line indicating plane of multiplanar reconstruction. DESS, Dual Echo Steady State; TFC, triangular fibrocartilage.

Loss of normal fibrillar signal pattern and high T2 signal intensity were criteria to identify a ligament tear. Location of tear was defined as dorsal, membranous or volar. The tear was defined as partial if there was poorly defined high T2 signal, without clear discontinuity of the ligament (Table 1). Clear ligament discontinuity with detachment from the bone or complete non-visualization of normal ligament fibres were defined as full thickness tears. Associated signs like widened scapholunate or lunotriquetral interval, step along the proximal and middle Gilula’s arcs on coronal T2 DESS and lunate tilt on sagittal wrist reformats were also recorded as findings supporting an intrinsic ligament tear.

Table 1.

Grades of intrinsic ligament tears at 3T MRI with arthroscopic correlation

Assessment of proximal carpal row intrinsic wrist ligaments	MRI finding on T2 DESS with true plane reformats	Arthroscopy finding (Geissler’s arthroscopic classification of carpal instability)
Partial tear Grade 1	T2 bright oedema and haemorrhage, preserved fibrillar ligament structure, no incongruity or malalignment	Ligament attenuation and hemorrhage, no incongruity
Full thickness tear (dorsal or volar with membranous) – Grade 2	T2 bright complete ligament substance discontinuity, mild (<2 mm) intercarpal interval widening	Ligament attenuation/hemorrhage with intercarpal gap less than width of arthroscopy probe
Full thickness tear (dorsal, membranous and volar) – Grade 3	Complete/near complete loss of ligament substance (dorsal, membranous and volar), intercarpal widening 2 mm or more, with step at Gilula’s arc	Ligament attenuation/hemorrhage with intercarpal gap allows passage of arthroscopy probe
Full thickness tear with static carpal malalignment Grade 4	Complete ligament tear with rotational malalignment (DISI or VISI)	Complete ligament tear with static rotational carpal malalignment

DESS, Dual Echo Steady State; DISI, Dorsal intercalated segment instability; VISI, Volar intercalated segment instability.

The TFC was assessed on dedicated coronal oblique reformats from 3D T2 DESS sequence. The body of TFC and its ulnar attachments (fovea and styloid tip), dorsal and volar distal radioulnar ligaments, ulnar collateral ligament/meniscus homologue, extensor carpi ulnaris tendon and subsheath and volar extrinsic ulnotriquetral ligament were assessed for tears. Cartilage defects, if any, were recorded and the presence of synovitis or effusion was noted. The dorsal intercarpal and radiocarpal ligaments and volar extrinsic wrist ligaments were assessed for tears.

Findings at arthroscopy were recorded for each patient (*anonimized), blinded to MRI findings. Tears of scapholunate or lunotriquetral interosseous ligament were identified as partial or complete using Geissler’s arthroscopic classification of carpal instability.⁵ Attenuation or hemorrhage of the interosseous ligament without incongruency of carpal alignment at arthroscopy (Grade 1) was considered equivalent to edema of the ligament with fibrillar preservation at MRI, without clear disruption or retraction of the ligament substance, described as an interosseous ligament strain/ incomplete injury.

Partial tears were described when there was incongruence visible at arthroscopy from midcarpal space, in addition to ligament attenuation and hemorrhage – Grade 2 if the gap was less than the width of the probe and Grade 3 if the gap allowed a probe to be passed through. At MRI, these were assessed based on complete loss of ligament substance involving either dorsal, membranous and volar components and full thickness retracted tears of the ligament components, associated with widening of the scapholunate or lunate-triquetral interval (Figures 4, 5a–d, 6a and b). The presence of rotational malalignment at arthroscopy or MRI, with increased scapholunate and radiolunate angles were classified as Grade 4 or complete interosseous tears with static carpal instability.

Figure 4.

Hemosiderin staining of volar scapholunate component, without a full thickness defect of the ligament substance (yellow arrow, a). The dorsal component is intact (arrow heads, b), Geissler Grade 1 partial scapholunate injury.

Figure 5.

Full thickness traumatic tear of the membranous component of scapholunate ligament with low signal retracted edges (solid white arrows) appreciated on coronal 3D T2 DESS, can be distinguished from developmental perforations. Additional findings of a step at middle Gilula’s arc (dashed arrow) and a unicortical fracture at the scaphoid ridge (thick blue arrow) b,c,d: axial oblique reformats show further tears involving volar (dashed arrow) and dorsal components of the scapholunate ligament (solid arrow). Sagittal reformat showed a dorsal lunate tilt (5c – thick white arrow) Arthroscopy confirmed Geissler Grade 4 scapholunate injury (5d). DESS, Dual Echo Steady State.

Figure 6.

Scapholunate ligament tear involving dorsal (solid white arrow), membranous (arrowhead) and volar (dashed arrow) components, with widened scapholunate interval (star) and no static carpal malalignment. Arthroscopy confirmed a Geissler Grade 3 scapholunate injury (6b).

Tears of the TFC were defined as foveal or ulnar styloid tip tears (traumatic pattern, peripheral tears), or tears of the body of TFC (degenerate or developmental pattern) (Figure 7a and b). Arthroscopy findings were then compared to MRI findings for scapholunate (SL), lunotriquetral (LT) ligaments and TFCC. MRI and arthroscopy were compared and recorded as either concordant or discordant. Positive-predictive value (PPV), negative-predictive value (NPV), specificity, sensitivity and overall accuracy were then calculated. This study was approved by the Trust Clinical Governance Board.

Figure 7.

Complete tear of ulnar styloid tip and foveal attachment of TFC (arrows, a) and near complete tear of the ulnar attachments (b) on coronal oblique reformats of 3D T2DESS. DESS, Dual Echo Steady State; TFC, triangular fibrocartilage.

Results

The overall diagnostic accuracy of 3T MRI using isotropic 3D T2 DESS sequence with dedicated oblique axial and coronal reformats was 91%, with a sensitivity of 83%, specificity of 91% and negative-predictive value of 95%.

Scapholunate ligament

MRI showed a sensitivity and specificity of 87 and 90% respectively in identifying scapholunate ligament injuries. 3T MRI wrist had a positive-predictive value of 81% and a negative-predictive value of 93% when assessing the scapholunate ligament, with an overall accuracy of 89%. (Table 2)

Table 2.

Diagnostic performance of 3T MRI with 3D T2 DESS in detecting intrinsic wrist ligament and TFCC tears

	SL	TFCC	LT	Overall
PPV	81%	89%	83%	85%
NPV	93%	100%	93%	95%
Sensitivity	87%	100%	63%	83%
Specificity	90%	86%	97%	91%
Accuracy	89%	93%	91%	91%

DESS, Dual Echo Steady State; LT: Lunotriquetral ligament, NPV: Negative predictive value SL: Scapholunate ligament,PPV: Positive predictive value, TFCC: Triangular Fibrocartilage Complex.

Triangular fibrocartilage complex

MRI wrist showed a sensitivity of 100% and a specificity of 86% for identifying triangular fibrocartilage complex injuries including foveal, central or dorsal tears, partial and full thickness injuries. MRI results showed a positive-predictive value of 89% and a negative-predictive value of 100% with an accuracy of 93%. Overall accuracy of MRI was highest in detection of triangular fibrocartilage complex injuries.

Lunotriquetral ligament

MRI showed a sensitivity of 63% and a specificity of 97% for identifying partial or complete tear of the volar, membranous or dorsal component of the lunotriquetral ligament (Figure 8a–c). MRI results showed a positive-predictive value of 83% and a negative-predictive value of 93% with an accuracy of 91%.

Figure 8.

Full thickness traumatic tear of the membranous component of lunate triquetral ligament with low signal retracted edges (magnified insert - arrow heads). There is a further undisplaced fracture of the ulnar styloid (white arrow) (8a). Sagittal reformat of the wrist shows a volar lunate tilt (8b) 8c: axial oblique reformat of the lunate triquetral ligament shows loss of definition of dorsal (solid arrow) and volar fibres (dashed arrow) suggesting these are torn. Arthroscopy confirmed a Grade 4 lunate triquetral injury.

There were eight MRI studies with findings discordant to arthroscopy. Three of these were false positive for scapholunate ligament tear, one false-positive for TFC and lunotriquetral tear and one was false-positive for TFC tear. The presence of a ganglion cyst within the ligament was the commonest cause for overcall of MRI for tears. A partial foveal tear of the TFC was found intact at arthroscopy done after 3 months, suggesting healed injury following MRI. There were three false-negative MRI studies, two for scapholunate tears and one for LT and TFC tears. On review, the commonest cause for a false-negative MRI was poor technical quality of the 3D T2 DESS sequence, resulting in suboptimal ligament assessment, and in one case this was contributed to by patient factors resulting in movement artifact due to discomfort in the wrist coil. Average interval between MRI and wrist arthroscopy was 184 days. 31% of patients had arthroscopy done within the first 100 days following their wrist MRI, 57% of patients had arthroscopy done more than 100 days following the MRI but less than a year and 11% of patients had their wrist arthroscopy over a year after their MRI.

Discussion

Intrinsic wrist ligamentous injuries (scapholunate, TFCC and lunotriquetral ligament) can occur following wrist trauma, with or without bony injury. These often occur in young individuals and can be overlooked due to difficulties in diagnosis with often normal initial plain radiographs. Plain radiographic findings of proximal carpal row instability due to ligament injury can take up to 3–12 months to become apparent as widened scapholunate interval and increased scapholunate angle (>60 degrees) in scapholunate ligament injury.⁵ Missed ligament injuries can cause chronic wrist pain and reduced grip strength.

The current study was designed to assess accuracy of unenhanced 3T MRI supplemented with axial oblique reformats for the scapholunate and lunate triquetral ligaments and coronal oblique reformats for TFCC tears from 3D T2 DESS sequence, in assessing tears of scapholunate, lunotriquetral ligaments and TFCC.

Radiologic evaluation with plain radiographs is the first imaging screening tool in investigating wrist trauma. MRI is performed if plain radiographs show normal findings and clinical provocative tests for a scaphoid fracture or ligament injury are positive. In addition to diagnosing radiographically occult scaphoid or other carpal fracture, MRI allows visualization of the intrinsic ligaments of the wrist, to allow detection of partial or complete tears.⁹ Over the last three decades, MRI has significantly improved with stronger magnetic field strength and dedicated extremity coils.

Magee et al studied intrinsic ligaments in their cohort using a fat-suppressed intermediate-weighted sequences, which is different to 3D T2 DESS used on our study.¹⁰ Their reported sensitivity for detection of TFCC tears (86%) was lower than our cohort (100%) and marginally higher for scapholunate and lunotriquetral tears. A possible reason could be a long interval between MRI and arthroscopy for some patients in our cohort, which can be a reason for discordant false-negative MRI findings reducing specificity of MRI. The two false-positive cases of partial scapholunate tears at MRI represented ganglion cysts at arthroscopy, as a cause for T2 bright signal on MRI.

Contrast-enhanced 3T wrist MRI was assessed in a small cohort (n = 18) by Ochman et al.¹¹ The MRI protocol was post-contrast 1.5 mm fat-saturated T₁ weighted images in three planes, supplemented with coronal T1 and Proton density fat saturated (PDFS) sequences; which is different to our study hence not directly comparable (Table 3).

Table 3.

Review of literature showing reported diagnostic performance of MRI in detecting intrinsic wrist ligament and TFCC tears

Study	Authors	PPV	NPV	Sensitivity	Specificity	Overall
Diagnostic accuracy of clinical examination and MRI for common articular wrist pathology	J.Ruston et al	62.5%	50.0%	47.6%	64.7%	55.3%
Comparison of 3 T MRI and Arthroscopy of Intrinsic Wrist Ligament and TFCC Tears	Magee et al	N/A	SL: 94% LT: 95%	TFCC:86% SL:89% LT: 82%	TFCC:100% SL:100% LT: 100%	N/A
High-resolution MRI (3T-MRI) in diagnosis of wrist pain: is diagnostic arthroscopy still necessary?	S.Ochman et al	TFCC R1:42% R2:45% SL + LT: R1:100% R2:21%	TFCC R1:83% R2:63% SL + LT: R1:93% R2:100%	TFCC R1:83% R2:83% SL + LT: R1:75% R2:75%	TFCC R1:42% R2:63% SL + LT: R1:100% R2:100%	N/A
Efficacy of MRI and Clinical Tests in Diagnostics of Wrist Ligament Injuries: A Systematic Review	Jonny K Andersson et al	N/A	TFCC, 37 to 90% SL, 72 to 94% LL, 74 to 95%.	N/A	N/A	N/A
Imaging non-specific wrist pain: interobserver agreement and diagnostic accuracy of SPECT/CT, MRI, CT, bone scan and plain radiographs	Huellner MW et al	80%	05%	65%	10%	56%
Scapholunate Interosseous Ligament Tears: Diagnostic Performance of 1.5 T, 3 T MRI, and MR Arthrography-A Systematic Review and Meta-analysis	Hafezi-Nejad N et al	N/A	N/A	3T MRI 75.7%	3T MRI 97.1%	N/A
Comparison of MRI & Direct MR Arthrography With Arthroscopy in Diagnosing Ligament Injuries of Wrist	Blessin S Cherian et al	TFCC:100% SL:100%	TFCC:80% SL:100%	TFCC:94.4% SL:75%	TFCC:100% SL:100% LT:95%	95.4%

LT: Lunotriquetral ligament, NPV: Negative predictive value SL: Scapholunate ligament,PPV: Positive predictive value,R1, first musculoskeletal radiologist; R2, Second musculoskeletal radiologist; TFCC: Triangular Fibrocartilage Complex.

In a systematic review, Andersson et al investigated if negative results at MRI or clinical provocation tests were enough to exclude clinically suspected wrist ligament injuries.⁵ Their results showed wide variation in negative-predictive value of MRI: 37–90% for TFCC, 72–94% for the scapholunate ligament and 74–95% for lunotriquetral ligament tears. They concluded that wrist arthroscopy remained the gold-standard for diagnosing wrist ligamentous tears. However, they stated that this gold-standard may change with improvements in high resolution MRI with thin slices and dedicated coils. The present study supports improved diagnostic performance of high resolution 3D T2 DESS on 3 T MRI, with an overall negative predictive value of 95% (93% for SL, 93% for LT and 100% for traumatic TFCC tears), which can support reduced need for diagnostic wrist arthroscopy in selected clinical scenarios.

Our study has some limitations. A retrospective study design meant that some patients’ MRI scans were not available to review on the local PACS system. Secondly, the variable interval between MRI and wrist arthroscopy can be a potential cause for discordant results, given that as the time gap increases, a tear can heal or new injury may occur. Lastly, our scans were evaluated by two experienced musculoskeletal radiology consultants in consensus, so inter- and intraobserver reliability has not been assessed.

Conclusion

3 T wrist MRI with dedicated true plane reformats from 3D T2 DESS have a high diagnostic accuracy in assessing for acute intrinsic ligament and TFCC injuries at the wrist. High strength 3 T MRI with good technical quality isotropic 3D T2 DESS sequence is critical for accurate wrist ligament assessment. Overall, negative-predictive values of 3 T MRI of 95% (93% for SL, 93% for LT and 100% for traumatic TFCC tears) can lead to reduced need for diagnostic arthroscopy of the wrist in selected clinical scenarios.