Carpal angles as measured on CT and MRI: can we simply translate radiographic measurements?

Comparison of computer-aided and manual measurements in the evaluation of carpal alignment

The purpose of this study was to compare computer-aided analysis and different methods of manual measurements in the evaluation of carpal alignment. The radioscaphoid, radiolunate, radiocapitate and radiometacarpal angles were measured on cone-beam computed tomography (CT) scans of 30 healthy wrists by automated software (Disior Ltd.) and by hand surgeons using lateral radiographs reconstructed from the CT data. Hand surgeons were either given (n = 6) or not given (n = 7) prior instructions on how to perform the measurements. Inter- and intra-observer reliability of manual measurements ranged from good to excellent (intra-class correlation coefficients [ICC] 0.77-0.99), being highest in specialists with standardized methods and in reconstructed radiographs with bone overlap digitally removed. Computer-aided software provided excellent intra-observer reliability (ICC 0.94-1.00) consistently and values that were highly comparable (mean difference range 1°-7°) with the manual measurements made in optimal settings. Computer-aided software provides an accurate and repeatable method to measure carpal alignment in CT scans, minimizing observational errors.

Imaging evaluation of a proposed 3D generative model for MRI to CT translation in the lumbar spine

BACKGROUND CONTEXT

A computed tomography (CT) and magnetic resonance imaging (MRI) are used routinely in the radiologic evaluation and surgical planning of patients with lumbar spine pathology, with the modalities being complimentary. We have developed a deep learning algorithm which can produce 3D lumbar spine CT images from MRI data alone. This has the potential to reduce radiation to the patient as well as burden on the health care system.

PURPOSE

The purpose of this study is to evaluate the accuracy of the synthetic lumbar spine CT images produced using our deep learning model.

STUDY DESIGN

A training set of 400 unpaired CTs and 400 unpaired MRI scans of the lumbar spine was used to train a supervised 3D cycle-Gan model. Evaluators performed a set of clinically relevant measurements on 20 matched synthetic CTs and true CTs. These measurements were then compared to assess the accuracy of the synthetic CTs.

PATIENT SAMPLE

The evaluation data set consisted of 20 patients who had CT and MRI scans performed within a 30-day period of each other. All patient data was deidentified. Notable exclusions included artefact from patient motion, metallic implants or any intervention performed in the 30 day intervening period.

OUTCOME MEASURES

The outcome measured was the mean difference in measurements performed by the group of evaluators between real CT and synthetic CTs in terms of absolute and relative error.

METHODS

Data from the 20 MRI scans was supplied to our deep learning model which produced 20 "synthetic CT" scans. This formed the evaluation data set. Four clinical evaluators consisting of neurosurgeons and radiologists performed a set of 24 clinically relevant measurements on matched synthetic CT and true CTs in 20 patients. A test set of measurements were performed prior to commencing data collection to identify any significant interobserver variation in measurement technique.

RESULTS

The measurements performed in the sagittal plane were all within 10% relative error with the majority within 5% relative error. The pedicle measurements performed in the axial plane were considerably less accurate with a relative error of up to 34%.

CONCLUSIONS

The computer generated synthetic CTs demonstrated a high level of accuracy for the measurements performed in-plane to the original MRIs used for synthesis. The measurements performed on the axial reconstructed images were less accurate, attributable to the images being synthesized from nonvolumetric routine sagittal T1-weighted MRI sequences. It is hypothesized that if axial sequences or volumetric data were input into the algorithm these measurements would have improved accuracy.

Assessing Diagnostic Accuracy of Four-dimensional CT for Instable Scapholunate Dissociation: The Prospective ACTION Trial

Background Timely treatment of scapholunate instability depends on early identification, but current imaging methods are either intricate or fail to demonstrate the dynamic stages. Purpose To calculate the diagnostic accuracy of four-dimensional (4D) CT for diagnosing instable scapholunate ligament (SLL) tears. Materials and Methods This prospective study enrolled consecutive participants with clinically suspected SLL tears who underwent 4D CT from July 2020 to May 2022. A historical study sample diagnosed at cineradiography served as a comparison, and wrist arthroscopy was the reference standard. Scapholunate joints greater than 3 mm were interpreted as instable at index 4D CT and cineradiography. Diagnostic accuracy was expressed as sensitivity and specificity. Areas under the receiver operating characteristic curve and cutoff values for both index tests were calculated. Intraclass correlation coefficients (ICCs) were computed to compare interrater reliability. Effective radiation doses at 4D CT were measured with thermoluminescent dosimeters. Results The study included 40 participants (mean age, 43 years ± 14 [SD]; 24 male) evaluated at 4D CT and 78 patients (mean age, 45 years ± 11; 50 male) historically evaluated at cineradiography. Four-dimensional CT helped detect instable tears in 26 of 35 participants (sensitivity, 74.3% [95% CI: 56.7, 87.5]. Cineradiography revealed instable tears in 52 of 63 patients (sensitivity, 82.5% [95% CI: 70.9, 91]). Four of five participants with stable scapholunate joints were identified at 4D CT (specificity, 80.0% [95% CI: 28.4, 99.5]), and 12 of 15 patients with stable SLLs were identified at cineradiography (specificity, 80.0% [95% CI: 51.9, 95.7]). Interrater agreement of radiologic measurements on 4D CT scans was good to excellent (ICC range, 0.89-0.96). The effective radiation dose ranged from 67 to 72 mSv at the wrist and was less than 1 mSv at the head. Conclusion Four-dimensional CT results are highly reproducible. Instable scapholunate joints greater than 3 mm were detected with a sensitivity of 74.3% and a specificity of 80% in an exploratory trial. Further evidence from larger randomized trials is warranted. German Register for Clinical Trials no. DRKS00021110 (Universal Trial Number U1111-1249-7884) Published under a CC BY 4.0 license. Supplemental material is available for this article. See also the editorial by Demehri and Ibad in this issue.

Computer-based three-dimensional measurement of carpal alignment: measurement techniques and normal ranges

The three-dimensional carpal alignment was measured in the neutral wrist position in 121 asymptomatic volunteers using computer-based cone-beam CT analysis. Normal values and the reliability of the automated analysis are reported. An analysis software based on segmentation of CT images and mathematical modelling was used to determine several axis variants based on different landmarks and to calculate the intercarpal angles automatically. Twenty wrists were imaged twice to determine intra-observer reliability. Mean values using the preferred axis variants were: scapholunate angle 57° (SD 9°), radiolunate angle 2° (SD 10°), lunocapitate angle -14° (SD 9°). Using alternate axis variants notably changed the angles produced. The intra-observer reliability of the analysis was excellent (mean intraclass correlation coefficient 0.97, SD 0.03). Computer-based CT analysis enables highly reproducible and automated assessment of carpal alignment. This study provides a reference database for measurement techniques and normal carpal angle values in three-dimensional imaging.

Results of treatment of osteoarthritis of the scaphotrapeziotrapezoidal joint with tendon allograft interposition

The aim of the study was to determine if the use of tendon allografts in combination with distal scaphoid resection for the treatment of isolated STT arthrosis is a save procedure. We reviewed the postoperative complications, re-operations, clinical and radiological results of this treatment modality. A retrospective cohort study was conducted. Investigated parameters include wrist mobility (wrist extension and -flexion), strength (grip- and pinch strength), patient-reported outcome scores : Visual Analogue Scale (VAS), Quick Disabilities of the Arm, Shoulder and Hand score (Q-DASH) and Patient Rated Wrist/Hand Evaluation score (PRWHE) and radiographic measurements : scapholunate (SL) angle, radiolunate (RL) angle and capitolunate (CL) angle. Ten wrists were included in nine patients. No revision surgery was performed. Two patients had transient neuropraxia of the radial nerve. Postoperative flexion-extension arc was 112°. Grip-strength was significantly increased after surgery (20 to 28kg). The average VAS score the past week was 1.75 (range 0-6.7), the average maximum VAS score was 3.0 (range 0-10). The mean PRWHE score was 16.6 (range 0- 69). The mean Q-DASH score was 17.95 (range 0-51). The current study indicates that distal scaphoid resection for isolated STT arthritis is a save procedure with minimal complications. It significantly improves grip strength. Mobility of the wrist was similar to contralateral wrist after surgery. Pain postoperatively was very limited (low VAS scores) and good functional scores (Q-DASH and PRWHE) were noted. Our findings support the prior findings that excisional arthroplasty might worsen carpal instability.

Radio-luno-triquetral bone-ligament transfer as an additional stabilizer in scapholunate-instability

INTRODUCTION

Reconstruction of the scapho-lunate (SL) ligament is still challenging. Many different techniques, such as capsulodesis, tendon graft and bone-ligament-bone graft have been described to stabilize reducible SL dissociation. If primary ligament repair alone is not possible, an additional stabilizer is needed to achieve scapho-lunate stability. A new local bone-ligament transfer using half of the radio-luno-triquetral ligament is performed. The direction of traction of the transposed ligament is very similar to the original ligament. Ideal tension can be attained by fixation of the bone block at the dorsal ridge of the scaphoid. The biomechanical stability of this bone-ligament transfer shall be examined biomechanically.

MATERIAL AND METHODS

Computed tomography imaging was performed using eight cadaveric forearms with a defined position of the wrist. Axial load was accomplished with tension springs attached to the extensor and flexor tendons. Three series ([a] native, [b] divided SL ligament and [c]) after reconstruction with bone-ligament transfer] were reconstructed three-dimensionally to determine the angles between radius, scaphoid and lunate. The radial distal part including a bone fragment of the radio-luno-triquetral ligament was transferred from its insertion at the distal edge of the radius to be attached to the dorsal ridge of the scaphoid.

RESULTS

SL gap was widened after its transection. Average SL distance was 6.6 ± 1.6 mm. After ligament reconstruction, the gap could be narrowed significantly to 4.2 mm (± 0.7 mm). The movement of the scaphoid and lunate showed significant changes, especially in wrist flexion, fist closure and radial deviation. These deviations could be corrected by the bone ligament transfer.

CONCLUSION

Reconstruction of a transected SL ligament with a bone-ligament transfer from the radio-luno-triquetral ligament reduces SL dissociation under axial load. The described surgical technique causes low donor-side morbidity and can be considered in addition to improve stability if SL ligament suture alone does not appear sufficient.

LEVEL OF EVIDENCE

Level II, therapeutic investigating experimental study.

Multiplanar reformation computed tomography for carpal malalignment

Correct interpretation of scaphoid axial length and carpal malalignment is difficult owing to the complex geometry of the scaphoid. Traditional measurements, such as the scapholunate angle and radiolunate angle, have shown limited reproducibility. To improve the assessment of these measurements, we used multiplanar reformation computed tomography with added average intensity projection. Four measurements for scaphoid morphology and carpal alignment were independently measured by four observers on computed tomography scans of 39 consecutive patients who were treated conservatively for scaphoid fracture. Fleiss's kappa for categorical results showed substantial agreement for the measurements of the scapholunate and radiolunate angles. Intraclass correlation coefficients were significant for measurements of the axial length, scapholunate angle and radiolunate angle. Our results suggest that multiplanar reformation computed tomography with added average intensity projection is a reliable technique for assessment of scaphoid morphology and carpal alignment. Level of evidence: II.

Radiographic/MR Imaging Correlation of the Wrist

In this review article, the authors discuss the imaging features of the most common pathologic conditions of the wrist by putting the emphasis on radiographic and MR imaging correlations. A topographic approach based on the 3 functional columns of the wrist (radial, central, and ulnar) serves as a framework. The pathologic conditions are classified, based on the structures involved, as fractures, ligament injuries, arthropathies, bone abnormalities, and tendinopathies. The authors describe and evaluate classic radiographic signs and explain how they correlate with MR imaging. The advantages and limitations of each technique are thoroughly discussed as well as other imaging modalities.

Four-dimensional CT Analysis of Wrist Kinematics during Radioulnar Deviation

Purpose To determine the technical feasibility of four-dimensional (4D) CT for analysis of the variation of radioscaphoid angle (RSA) and lunocapitate angle (LCA) during wrist radioulnar deviation. Materials and Methods In this prospective study, 37 participants suspected of having scapholunate instability were evaluated from January 2015 to December 2016 with 4D CT and CT arthrography (mean age ± standard deviation, 42.3 years ± 15; range, 21-75 years; 27 men [mean age, 44 years ± 15] and 10 women [mean age, 38 years ± 14]). Five angular parameters for RSA and LCA variation during radioulnar deviation were calculated by two independent readers. CT arthrography was used as the reference standard method for scapholunate ligament tear identification. Results In the control group (n = 23), the mean values for RSA were 103° ± 8 and 104° ± 9, whereas the mean values for LCA were 86° ± 9° and 90° ± 11° with a coefficient of variation of 11% and 13% for reader 1 and reader 2, respectively. The interobserver and intraobserver agreements were excellent for RSA and substantial to excellent for LCA. In the pathologic group (n = 14), LCA amplitude, standard deviation, and maximal angle were lower for both readers with respect to the control group, measuring 36% and 44% (P = .003), 37% and 44% (P = .002), and 13% and 19% (P = .003), respectively. RSA amplitude did not show statistically significant results in the pathologic group (P > .13). LCA yielded the highest sensitivity (71%-93%), whereas RSA yielded the highest specificity (87%-100%). Conclusion Semiautomatic four-dimensional CT analysis of the wrist during radioulnar deviation is technically feasible and reproducible for evaluation of carpal kinematic abnormalities. © RSNA, 2018 Online supplemental material is available for this article .

Analysis of tenodesis techniques for treatment of scapholunate instability using the finite element method

Chronic scapholunate ligament (SL) injury is a common disorder affecting the wrist. Despite advances in surgical techniques used to treat this injury, SL gap re-emergence may occur postoperatively. This paper presents an investigation into the performance of the Corella, schapolunate axis (SLAM), and modified Brunelli tenodesis (MBT) surgical reconstruction techniques used to treat scapholunate instability. Finite element (FE) models were used to undertake virtual surgery, and the resulting scapholunate (SL) gap and angle obtained using the 3 techniques were compared. The Corella technique was found to achieve the SL gap and angle closest to the intact (ligament) wrist, restoring SL gap and angle to within 5.6% and 0.6%, respectively. The MBT method resulted in an SL gap least close to the intact. The results of our study indicate that the contribution of volar scapholunate interosseous ligament to scapholunate stability could be important.

Evaluation of the performance of three tenodesis techniques for the treatment of scapholunate instability: flexion-extension and radial-ulnar deviation

Chronic scapholunate ligament (SL) injuries are difficult to treat and can lead to wrist dysfunction. Whilst several tendon reconstruction techniques have been employed in the management of SL instability, SL gap reappearance after surgery has been reported. Using a finite element model and cadaveric study data, we investigated the performance of the Corella, scapholunate axis (SLAM) and modified Brunelli tenodesis (MBT) techniques. Scapholunate dorsal and volar gap and angle were obtained following virtual surgery undertaken using each of the three reconstruction methods with the wrist positioned in flexion, extension, ulnar deviation and radial deviation, in addition to the ulnar-deviated clenched fist and neutral positions. From the study, it was found that, following simulated scapholunate interosseous ligament rupture, the Corella technique was better able to restore the SL gap and angle close to the intact ligament for all wrist positions investigated, followed by SLAM and MBT. The results suggest that for the tendon reconstruction techniques, the use of multiple junction points between scaphoid and lunate may be of benefit.

Graphical abstract

Imaging in carpal instability

Carpal instability is a complex and heterogeneous clinical condition. Management requires accurate identification of structural injury with an understanding of the resultant movement (kinematic) and load transfer (kinetic) failure. Static imaging techniques, such as plain film radiography, stress views, ultrasound, magnetic resonance, MR arthrography and computerized tomography arthrography, may accurately depict major wrist ligamentous injury. Dynamic ultrasound and videofluoroscopy may demonstrate dynamic instability and kinematic dysfunction. There is a growing evidence base for the diagnostic accuracy of these techniques in detecting intrinsic ligament tears, but there are limitations. Evidence of their efficacy and relevance in detection of non-dissociative carpal instability and extrinsic ligament tears is weak. Further research into the accuracy of existing imaging modalities is still required. Novel techniques, including four-dimensional computerized tomography and magnetic resonance, can evaluate both cross-sectional and functional carpal anatomy. This is a narrative review of level-III studies evaluating the role of imaging in carpal instability.