Computed tomography arthrography versus magnetic resonance imaging for diagnosis of osteochondral lesions of the talus

INTRODUCTION

Osteochondral lesions of the talus (OLT) usually have non-specific clinical symptoms, and radiographs have a low sensitivity for detecting OLT. The purpose of this study is to compare the diagnostic value of CT arthrography (CTa) with that of MRI using arthroscopy as the reference standard for grading OLT.

MATERIALS AND METHODS

We retrospectively reviewed patients who had OLT between 2015 and 2020. Patients with symptomatic OLT as a surgical indication, who were treated arthroscopically, and underwent both CTa and MRI before surgery were included. OLT was evaluated by both CTa and MRI using arthroscopy as the standard. We graded CTa, MRI, arthroscopic findings using Mintz classification.

RESULTS

Thirty-five patients were included. Accuracy rates of MRI and CTa for grading OLT, compared to those of arthroscopy, were 57.1% and 88.6%, respectively. Among 15 mismatched cases in MRI, 12 lesions (80%) were matched in CTa and arthroscopy. CTa had significantly higher diagnostic performance than MRI for the detection of grade III lesions (p = 0.041). Using the receiver operating characteristics curves, the area under the curve values for lesion grading were 0.893 for CTa and 0.762 for MRI.

CONCLUSION

CTa was statistically significantly better in detecting chondral flapping or subchondral exposure lesions for OLT than MRI on using arthroscopy as the reference standard. Because the stability of the OLT is essential in determining the treatment method, if an OLT is observed on MRI and is suspected to cause ankle pain, we recommend additional CTa examination to determine the more correct treatment strategies for OLT.

LEVEL OF EVIDENCE

Diagnostic Level III.

Proposal of a new CT arthrographic classification system of osteochondral lesions of the talus

BACKGROUND

Surgical treatment of osteochondral lesions of the talus (OLT) is warranted if medical treatments fail, achieving good results in around 85% of cases. Numerous classification systems, based on all possible imaging modalities (radiography, MRI, CT scan, scintigraphy, and CT arthrography), have been proposed to guide surgical treatments, but none has proven to be superior. A recent study demonstrated the prognostic value of CT arthrography by accurately describing the subchondral bone plate. A systematic review of the literature has brought new criteria to predict good outcome following bone marrow stimulation surgical techniques: lesions should measure less than 1 centimeter in size and 5 millimeters in depth. Based on these data, we are proposing a new simple, 3-stage CT arthrographic classification system of OLT.

MATERIALS AND METHODS

After a brief overview of the classification, 60 CT-arthrographies of ankles with OLT were organized according to this new CT arthrographic classification system by four surgeons (two juniors and two seniors). Two imaging assessments were performed one month apart. Statistical analysis was performed using the Fleiss' kappa coefficient to determine the inter- and intraobserver agreement.

RESULTS

An excellent inter- and intraobserver agreement was found with overall Fleiss' kappa coefficients of 0.897 and 0.847, respectively.

CONCLUSION

The results of our study showed an excellent inter- and intraobserver agreement for this new CT arthrographic classification system of OLT. The principal advantage of this new classification system, based on the latest data in the literature, is its ability to easily distinguish lesions that are more amenable to bone marrow stimulation techniques.

LEVEL OF EVIDENCE

II.

Dual-energy CT arthrography: a feasibility study

OBJECTIVE

To evaluate the feasibility of producing 2-dimensional (2D) virtual noncontrast images and 3-dimensional (3D) bone models from dual-energy computed tomography (DECT) arthrograms and to determine whether this is best accomplished using 190 keV virtual monoenergetic images (VMI) or virtual unenhanced (VUE) images.

MATERIALS AND METHODS

VMI and VUE images were retrospectively reconstructed from patients with internal derangement of the shoulder or knee joint who underwent DECT arthrography between September 2017 and August 2019. A region of interest was placed in the area of brightest contrast, and the mean attenuation (in Hounsfield units [HUs]) was recorded. Two blinded musculoskeletal radiologists qualitatively graded the 2D images and 3D models using scores ranging from 0 to 3 (0 considered optimal).

RESULTS

Twenty-six patients (mean age ± SD, 57.5 ± 16.8 years; 6 women) were included in the study. The contrast attenuation on VUE images (overall mean ± SD, 10.5 ± 16.4 HU; knee, 19.3 ± 10.7 HU; shoulder, 5.0 ± 17.2 HU) was significantly lower (p < 0.001 for all comparisons) than on VMI (overall mean ± SD, 107.7 ± 43.8 HU; knee, 104.6 ± 31.1 HU; shoulder, 109.6 ± 51.0 HU). The proportion of cases with optimal scores (0 or 1) was significantly higher with VUE than with VMI for both 2D and 3D images (p < 0.001).

CONCLUSIONS

DECT arthrography can be used to produce 2D virtual noncontrast images and to generate 3D bone models. The VUE technique is superior to VMI in producing virtual noncontrast images.

Proximal Horizontal Flap Tears of TFCC Diagnosed by Computed Tomography Arthrography: Six Case Series

Background  Proximal horizontal tears of the triangular fibrocartilage complex (TFCC) represent the tears at the proximal surface of the articular disk with a normal appearance of the distal surface. Preoperative diagnosis of TFCC flap tears is challenging. Objectives  This report aims to present a diagnostic method using computed tomography (CT) arthrography for the proximal horizontal flap tears of the TFCC and to report our clinical outcomes. Patients and Methods  Six patients were included who were preoperatively suspected to have proximal horizontal flap tears of the TFCC via CT arthrography. Arthrography was conducted by injecting dye into the distal radioulnar joint (DRUJ), and CT images were obtained immediately following arthrography. We performed arthroscopic or direct flap debridement with concomitant surgeries: ulnar shortening with positive ulnar variance and corrective osteotomy with the malunion following distal radius fracture. Results  Preoperative CT arthrography clearly revealed the flaps to be flipped over toward the radiopalmar side of the DRUJ in four cases and a teardrop-shaped dye defect in two. We were able to identify the dislocated flap by arthroscopy avulsed from the proximal aspect of the articular disk within the DRUJ in all six cases. The mean pain level decreased from 10 preoperatively to 0.3 postoperatively on the visual analog scale. The mean patient-rated wrist evaluation score decreased from 43.5 preoperatively to 11.2 postoperatively. Conclusions  Our study shows that CT arthrography can be a promising method for diagnosing proximal horizontal flap tears of the TFCC. Debridement of the flaps and concomitant surgeries showed satisfactory clinical results. Level of Evidence  This is a Level 4, diagnostic study.

Giant intraosseous ganglion of the fibula: multimodality imaging

Intraosseous ganglia around the knee are most commonly located in the proximal tibia and limited to the epiphyseal-metaphyseal region. We report the case of a giant intraosseous ganglion of the fibula. MRI demonstrated the fluid avascular content of the lesion. CT arthrography of the knee demonstrated partial opacification of the lesion through a cortical bone defect. The lesion was treated with curettage and bone grafting. Anatomopathological examination confirmed the medical imaging diagnosis of intraosseous ganglion. This case highlights the value of joint opacification with CT arthrography to demonstrate the communication between the articular cavity and the ganglion.

Fracture of the polyethylene tibial post in the posterior-stabilized total knee prosthesis: arthrographic and CT arthrographic diagnosis

Fracture of the polyethylene tibial post in the posterior-stabilized total knee prosthesis is often delayed in diagnosis due to its nonspecific symptoms and the radiolucent characteristic of polyethylene on conventional radiography. Therefore, the diagnosis is always established by arthroscopy. Notwithstanding recent advances in imaging modalities, we are presently aware of only two related case reports on MRI and even no reports about arthrographic or CT-arthrographic diagnosis of fractured tibial post. We hereby report a case of a 58-year-old female patient who developed recurrent knee pain during the third year after total knee arthroplasty. The displaced polyethylene tibial post was clearly outlined by administered contrast material in the posterior knee. Under the diagnosis of fracture of the tibial post, the patient underwent isolated replacement of the broken polyethylene insert. Her knee pain significantly improved after the operation.

Rotator cuff muscles fatty infiltration increases with age: retrospective review of 210 patients with intact cuff on computed tomography arthrography

HYPOTHESIS

We aimed to demonstrate that rotator cuff fatty infiltration (FI) increases physiologically with age and that a FI degree of 2 might be encountered in patients with an intact cuff.

METHODS

We retrospectively evaluated the FI of 210 patients (classified in 7 age groups: <20, 20-30, 30-40, 40-50, 50-60, 60-70, and >70 years) who had an intact cuff on computed tomography (CT) arthrography. The Goutallier grading system was used to assess FI of rotator cuff muscles and of the deltoid muscle. FI was then compared between groups for each muscle, and determinants (age, sex, and body mass index) of FI were assessed.

RESULTS

FI of all evaluated muscles progressively increased with age, but a statistically significant increase between 2 consecutive age groups was observed for all muscles only after age 40 years. For each group, intermuscle comparison showed that the FI distribution was not significantly different between each rotator cuff muscle at any age. Age was a determinant for FI for all muscles, but sex and body mass index also influenced deltoid FI. A median FI value of 2 was found in the "over 70 group" for the supraspinatus, but in the 60 to 70 group for infraspinatus and subscapularis and in the 50 to 60 group for the deltoid.

CONCLUSION

FI of rotator cuff muscles increased with age, with a significant acceleration after 40 years. Moreover, a FI graded 2, a common threshold for management decision, was commonly found in those aging patients with intact cuff on CT arthrography.

Relationships between cartilage thickness and subchondral bone mineral density in non-osteoarthritic and severely osteoarthritic knees: In vivo concomitant 3D analysis using CT arthrography

OBJECTIVE

To test whether subchondral bone mineral density (sBMD) and cartilage thickness (CTh) of femoral condyles are correlated in knees without and with severe medial femorotibial osteoarthritis (OA), using a subregional analysis with computerized tomography (CT) arthrography.

METHODS

CT arthrograms of 50 non-OA (18 males, 58.7 (interquartile range (IQR) = 6.6 years)) and 50 severe medial OA (24 males, 60.5 (IQR = 10.7) years) knees, were retrospectively analyzed. Bone and cartilage were segmented using custom-designed software, leading to 3D models on which each point of the subchondral surface is given a CTh and sBMD value. The average sBMD and CTh were then calculated for the entire weight-bearing regions as well as specific subregions of interest. Linear bivariate and multivariable analyses were performed to test for relationships between sBMD and CTh (regional and subregional measures, or medial-to-lateral ratios), with confounders of age, gender, femoral bone size and femorotibial angle.

RESULTS

In non-OA knees, the sBMD and CTh medial-to-lateral ratios were positively correlated for the total region and the external and internal subregions (r ≥ 0.341, P ≤ 0.015). In OA knees, sBMD and CTh medial-to-lateral ratios were negatively correlated for the total region and the external and central subregions (r ≤ -0.538, P < 0.001). Additional positive/negative relationships in the non-OA/OA knees were observed between sBMD and CTh measures in the medial compartment.

CONCLUSIONS

The positive correlation between sBMD and CTh in non-OA knees, and the negative one in OA knees, bring support to the theory of a subchondral bone/cartilage functional unit, which could help to better understand the pathophysiology of OA.

Meniscal sizing before allograft: Comparison of three imaging techniques

BACKGROUND

Accuracy of meniscal sizing is an important issue before allograft transplantation. To date, there is no consensus on the best imaging method. The purpose of this study was to compare plain radiographs, magnetic resonance imaging (MRI) and computed tomography (CT) arthrography in the assessment of meniscal size. We hypothesized that MRI and CT arthrography had better correlations than plain radiographs.

METHODS

All patients operated on by meniscal allograft between January 2005 and May 2015 were screened. Among them, 32 patients had both preoperative radiographs, MRI and CT arthrography of the affected knee. The meniscal dimensions were evaluated, blindly and randomly, using three imaging methods. A correlation analysis between each technique was made. For radiographic methods, an additional comparison was made between original Pollard's method and the modified method (Yoon). Bone dimensions (tibial metaphysis) were also collected, using radiographs and MRI, in order to build new equations allowing determination of meniscal dimensions from those bone measurements.

RESULTS

The radiographic methods offered satisfying evaluations of the meniscal dimensions in the sagittal plane, without significant difference when compared with CT arthrography or MRI. In the frontal plane, the radiograph methods were less effective. With new equations, allowing determination of meniscal dimensions from tibial plateau dimensions, the mean correlation coefficient was 0.39 (0.14-0.71).

CONCLUSIONS

The correlation between radiographic methods and MRI depended on which parameter (frontal or sagittal) was measured. Thus, we proposed a new method for sizing of meniscus, easily measurable from bony landmarks, aiming to improve the accuracy of graft selection.

CT arthrography visualizes tissue growth of osteochondral defects of the talus after microfracture

PURPOSE

Little is known about the arthroscopic or radiographic outcomes after arthroscopic microfracture of osteochondral lesions of the talus (OLTs). The purpose of this study was to investigate tissue growth after arthroscopic microfracture of OLTs using computed tomography arthrography (CTA) and to identify the relationship between CTA findings and clinical outcomes. We hypothesized that the morphology of the repaired tissue would be similar to that of normal anatomy and correlate with the clinical outcomes.

METHODS

Forty-two ankles treated using arthroscopic microfracture of OLTs between 2009 and 2014 were monitored. CTA was performed post-operatively at 6 months and at 1 and 2 years after surgery. The post-operative thickness of the repaired tissue associated with OLT (grade) and the volume of the subchondral cystic lesions were evaluated using CTA. Clinical outcomes, including the pain visual analog scale (VAS) and American Orthopaedic Foot and Ankle Society (AOFAS) ankle functional scores, were evaluated and correlated with CTA.

RESULTS

The proportion of fully grown tissue (grade 3) increased over time; specifically, the rates were 12/40 (33.3%) at 6 months, 11/18 (61.1%) at 1 year, and 8/10 (80%) at 2 years after surgery (p = 0.005). The VAS pain (p < 0.001) and AOFAS scores (p < 0.001) were also improved at the final follow-up; however, they were not associated with repaired tissue thickness as shown by CTA (n.s.).

CONCLUSIONS

After microfracture of OLTs, tissue growth in the osteochondral defects was well visualized using CT arthrography and was observed in most cases. However, the CTA findings were not related to the clinical outcomes.

LEVEL OF EVIDENCE

IV.

Uncommon observation of bifocal giant subchondral cysts in the hip: diagnostic role of CT arthrography and MRI, with pathological correlation

Subchondral cysts (or geodes) are common in osteoarthritis (OA), usually in association with other typical signs, i.e., joint space narrowing, subchondral bone sclerosis, and osteophytosis. However, large lesions without the typical signs of OA or lesions located outside the weight-bearing areas are unusual and may be confused for other conditions, in particular, those of tumoral origin. We report the findings in a 48-year-old man who had been complaining of left buttock pain for 3 years, getting worse over the last year, and an evolutive limited range of motion of the hip. The pain was increased by weight-bearing and was not relieved by nonsteroidal anti-inflammatory drugs. Radiographs and CT showed a large multilocular lytic lesion within the femoral head and a large lytic lesion in the left ilio-ischiatic ramus, raising the question of bifocal tumoral involvement. On MRI, the lesions had low signal intensity on T1- and high signal intensity on T2-weighted MR images, with subtle peripheral enhancement on post-contrast T1-weighted images. CT arthrography, by demonstrating a communication between the femoral head and ischiatic cysts and the joint space allowed us to definitively rule out malignant conditions and to make the diagnosis of subchondral bone cysts. Total hip arthroplasty was performed. Pathological analysis of the resected femoral head and of material obtained at curettage of the ischiatic lesion confirmed the diagnosis of degenerative geodes. This case illustrates an atypical bifocal location of giant subchondral cysts in the hip joint mimicking lytic tumors, in the absence of osteoarthritis or rheumatoid arthritis, and highlights the role of CT arthrography in identifying this condition.

Shoulder Anatomy and Normal Variants

The shoulder joint is functionally and structurally complex and is composed of bone, hyaline cartilage, labrum, ligaments, capsule, tendons and muscles. It links the trunk to the upper limb and plays an important biomechanical role in daily activities. Indications for imaging of the shoulder have considerably increased in the last few years. The article focuses mainly on Magnetic Resonance Imaging (MRI) as well as MR and CT arthrography, diagnostic procedures of choice for assessment of internal derangement of the shoulder. Bony components, rotator cuff tendons and muscles can be assessed on MR imaging without arthrographic technique, whereas the articular structures (including glenohumeral ligaments, capsulolabral structures and hyaline cartilage) require arthrography for more accurate assessment. Appropriate MR imaging protocols and sequences and applied MR anatomy of the shoulder (including normal variants) are proposed to help assist management and treatment of common shoulder pathologies encountered (such as rotator cuff tears, impingement syndromes, and instability as well as less frequent causes of shoulder pain). The most common variants and pitfalls are related to the anterosuperior aspect of the shoulder joint. Basic anatomy as well as recent findings are developed, including a new description of the attachment of supraspinatus and infraspinatus tendons at the superior aspect of the humerus, the rotator cable and the superior glenohumeral ligament complex.

Glenohumeral position during CT arthrography with arthroscopic correlation: optimization of diagnostic yield

OBJECTIVE

To evaluate the diagnostic yield of two acquisitions of single-contrast CT arthrography (CTA) of the shoulder in internal, neutral, or external glenohumeral rotation with arthroscopic correlation.

MATERIALS AND METHODS

The CT study was obtained using two acquisitions (first the humerus positioned in maximum tolerated external rotation with the arm along the body and the second with the humerus in internal rotation with the palm placed flat on the table). Two independent readers blinded to the arthroscopic results evaluated the CTA images for labral tears, glenoid bone loss/fractures, and cartilage loss. For each CTA acquisition, sensitivity and specificity for detection of the aforementioned pathology were assessed. Inter-reader agreement was quantified by weighted ĸ statistics.

RESULTS

Sensitivity and specificity for detecting anteroinferior or posterior labral tears was highest with neutral rotation (sensitivity 91-100%, specificity 61-100%). For glenoid fracture, sensitivity (67%) was highest with external rotation and specificity (100%) was highest with internal rotation. For cartilage loss, sensitivity (64%) and specificity (89%) was highest with external rotation and neutral rotation, respectively. Neutral rotation showed high sensitivity and specificity for glenoid fractures and cartilage loss. Inter-reader agreement ranged from fair to very good.

CONCLUSIONS

Neutral glenohumeral position in shoulder CT arthrography was adequately sensitive and specific for the detection of intra-articular pathology, avoiding the use of more than one acquisition.

Quantitative in vivo CT arthrography of the human osteoarthritic knee to estimate cartilage sulphated glycosaminoglycan content: correlation with ex-vivo reference standards

OBJECTIVE

Recently, computed tomography arthrography (CTa) was introduced as quantitative imaging biomarker to estimate cartilage sulphated glycosaminoglycan (sGAG) content in human cadaveric knees. Our aim was to assess the correlation between in vivo CTa in human osteoarthritis (OA) knees and ex vivo reference standards for sGAG and collagen content.

DESIGN

In this prospective observational study 11 knee OA patients underwent CTa before total knee replacement (TKR). Cartilage X-ray attenuation was determined in six cartilage regions. Femoral and tibial cartilage specimens harvested during TKR were re-scanned using equilibrium partitioning of an ionic contrast agent with micro-CT (EPIC-μCT), which served as reference standard for sGAG. Next, cartilage sGAG and collagen content were determined using dimethylmethylene blue (DMMB) and hydroxyproline assays. The correlation between CTa X-ray attenuation, EPIC-μCT X-ray attenuation, sGAG content and collagen content was assessed.

RESULTS

CTa X-ray attenuation correlated well with EPIC-μCT (r = 0.76, 95% credibility interval (95%CI) 0.64 to 0.85). CTa correlated moderately with the DMMB assay (sGAG content) (r = -0.66, 95%CI -0.87 to -0.49) and to lesser extent with the hydroxyproline assay (collagen content) (r = -0.56, 95%CI -0.70 to -0.36).

CONCLUSIONS

Outcomes of in vivo CTa in human OA knees correlate well with sGAG content. Outcomes of CTa also slightly correlate with cartilage collagen content. Since outcomes of CTa are mainly sGAG dependent and despite the fact that further validation using hyaline cartilage of other joints with different biochemical composition should be conducted, CTa may be suitable as quantitative imaging biomarker to estimate cartilage sGAG content in future clinical OA research.

Prospective Evaluation of Agreement and Accuracy in the Diagnosis of Meniscal Tears: MR Arthrography a Short Time After Injection Versus CT Arthrography After a Moderate Delay

OBJECTIVE

The purpose of this study was to compare the performance of direct CT arthrography performed after a moderate injection delay with that of MR arthrography performed soon after injection in the diagnosis of meniscal tears.

SUBJECTS AND METHODS

Twenty-five patients underwent direct MR arthrography followed by same-day CT arthrography of the knee. Two blinded musculoskeletal radiologists independently reviewed the MR and CT arthrographic images for the presence of medial or lateral meniscal tears in the anterior horn, body, and posterior horn. Their readings were compared with a reference standard reading, which was based on post-MRI arthroscopic findings (n = 11) or the consensus opinion of two other musculoskeletal radiologists who simultaneously reviewed the paired CT and MR arthrographic examinations using all available clinical, surgical, and imaging information. The individual and combined radiologist agreements with the reference standard were calculated for each modality.

RESULTS

Interreader agreement was 91% for MR arthrography and 85% for CT arthrography. The overall combined radiologist agreement with the reference standard was 91% for MR arthrography and 86% for CT arthrography (p = 0.03). For the two readers, the overall accuracy rates for diagnosing a meniscal tear were 82% and 88% with MR arthrography and 74% and 76% with CT arthrography. Only 50% (3/6) of surgically proven tears imbibed gadolinium.

CONCLUSION

Although MR arthrography performed soon after the contrast injection had higher interreader agreement and greater accuracy, CT arthrography performed after a mean postinjection delay of 100 minutes was moderately accurate in the diagnosis of meniscal tears and can be used as an alternative procedure when MR arthrography cannot be completed.

External rotation and active supination CT arthrography for the postoperative evaluation of type II superior labral anterior to posterior lesions

PURPOSE

To evaluate the effectiveness of external rotation and active supination CT arthrography in postoperative evaluation by comparing it with neutral CT arthrography and analyzing its agreement with postoperative clinical results after the repair of type II superior labral anterior to posterior (SLAP) lesions.

MATERIALS AND METHODS

A total of 25 patients who had undergone CT arthrography in neutral, external rotation and active supination position at least 1 year after the arthroscopic repair of SLAP lesions were enrolled. Two radiologists independently evaluated the status of the repaired SLAP lesions with neutral CT arthrography and then with external rotation and active supination CT arthrography.

RESULTS

Five patients had residual symptoms and positive findings upon SLAP-specific examinations. Agreements between the presence of symptoms and radiologic diagnoses based on neutral CT arthrography were insignificant for reader 1 (κ = 0.138, p = n.s.) and significant for reader 2 (κ = 0.328, p = 0.027). However, agreements were highly significant in the analysis following the evaluation of external rotation and active supination CT arthrography for both readers (κ = 0.694, p < 0.001 in reader 1; κ = 0.783, p < 0.001 in reader 2).

CONCLUSIONS

The presence of contrast-filled gaps between the labrum and glenoid on neutral CT arthrography after SLAP repair is frequent with satisfactory clinical outcomes. Gaps without additional widening upon external rotation and active supination CT arthrography may suggest postoperatively stable biceps anchors, so this new method could minimize the overdiagnosis of recurrent SLAP lesions. Additional gap widening on external rotation and active supination CT arthrography could be related to a true recurrent SLAP lesion and the symptoms of the patients.

LEVEL OF EVIDENCE

Case series, Level IV.

Advanced imaging of the scapholunate ligamentous complex

The scapholunate joint is one of the most involved in wrist injuries. Its stability depends on primary and secondary stabilisers forming together the scapholunate complex. This ligamentous complex is often evaluated by wrist arthroscopy. To avoid surgery as diagnostic procedure, optimization of MR imaging parameters as use of three-dimensional (3D) sequences with very thin slices and high spatial resolution, is needed to detect lesions of the intrinsic and extrinsic ligaments of the scapholunate complex. The paper reviews the literature on imaging of radial-sided carpal ligaments with advanced computed tomographic arthrography (CTA) and magnetic resonance arthrography (MRA) to evaluate the scapholunate complex. Anatomy and pathology of the ligamentous complex are described and illustrated with CTA, MRA and corresponding arthroscopy. Sprains, mid-substance tears, avulsions and fibrous infiltrations of carpal ligaments could be identified on CTA and MRA images using 3D fat-saturated PD and 3D DESS (dual echo with steady-state precession) sequences with 0.5-mm-thick slices. Imaging signs of scapholunate complex pathology include: discontinuity, nonvisualization, changes in signal intensity, contrast extravasation (MRA), contour irregularity and waviness and periligamentous infiltration by edema, granulation tissue or fibrosis. Based on this preliminary experience, we believe that 3 T MRA using 3D sequences with 0.5-mm-thick slices and multiplanar reconstructions is capable to evaluate the scapholunate complex and could help to reduce the number of diagnostic arthroscopies.

Shape-based acetabular cartilage segmentation: application to CT and MRI datasets

PURPOSE

A new method for acetabular cartilage segmentation in both computed tomography (CT) arthrography and magnetic resonance imaging (MRI) datasets with leg tension is developed and tested.

METHODS

The new segmentation method is based on the combination of shape and intensity information. Shape information is acquired according to the predictable nonlinear relationship between the U-shaped acetabulum region and acetabular cartilage. Intensity information is obtained from the acetabular cartilage region automatically to complete the segmentation procedures. This method is evaluated using 54 CT arthrography datasets with two different radiation doses and 20 MRI datasets. Additionally, the performance of this method in identifying acetabular cartilage is compared with four other acetabular cartilage segmentation methods.

RESULTS

This method performed better than the comparison methods. Indeed, this method maintained good accuracy level for 74 datasets independent of the cartilage modality and with minimum user interaction in the bone segmentation procedures. In addition, this method was efficient in noisy conditions and in detection of the damaged cartilages with zero thickness, which confirmed its potential clinical usefulness.

CONCLUSIONS

Our new method proposes acetabular cartilage segmentation in three different datasets based on the combination of the shape and intensity information. This method executes well in situations where there are clear boundaries between the acetabular and femoral cartilages. However, the acetabular cartilage and pelvic bone information should be obtained from one dataset such as CT arthrography or MRI datasets with leg traction.

Assessment of painful total shoulder arthroplasty using computed tomography arthrography

BACKGROUND

This study assessed the accuracy of computed tomography (CT) arthrography when evaluating glenoid component stability in the setting of postarthroplasty shoulder pain.

METHODS

We retrospectively reviewed all patients presenting to the clinic during a 5.5-year period to identify those with a painful shoulder arthroplasty more than 1 year after the index procedure. We excluded reverse and hemiarthroplasty procedures, patients with a clearly identifiable cause for pain, such as rotator cuff insufficiency or gross component loosening as seen on plain radiographs, and those with culture-positive aspiration. There were 14 patients with suspected glenoid component loosening but inconclusive plain radiographs. Each of the 14 patients underwent a CT arthrogram that was evaluated by the senior author (J.J.P.W.) for the presence or absence of contrast material underneath the polyethylene component. Operative reports and surgical videos from subsequent arthroscopy were reviewed to assess glenoid component stability as determined by direct arthroscopic visualization.

RESULTS

CT arthrography suggested glenoid component loosening in 8 of 14 patients (57.1%), and arthroscopic inspection identified loosening in 10 of 14 patients (71.4%). In 3 of 10 patients (30%), CTA suggested a well-fixed glenoid component, but gross loosening was identified during arthroscopy. In this study, CTA yielded a sensitivity of 70%, a specificity of 75%, a positive predictive value of 87.5%, and a negative predictive value of 50.0%.

CONCLUSION

CTA had a low negative predictive value (50%), and therefore, the prediction of component stability based on the absence of contrast between the glenoid component and the bone-cement interface does not always reflect true stability.

MDCT arthrography of the hip: value of the adaptive statistical iterative reconstruction technique and potential for radiation dose reduction

OBJECTIVE

The purpose of this article is to assess the effect of the adaptive statistical iterative reconstruction (ASIR) technique on image quality in hip MDCT arthrography and to evaluate its potential for reducing radiation dose.

SUBJECTS AND METHODS

Thirty-seven patients examined with hip MDCT arthrography were prospectively randomized into three different protocols: one with a regular dose (volume CT dose index [CTDIvol], 38.4 mGy) and two with a reduced dose (CTDIvol, 24.6 or 15.4 mGy). Images were reconstructed using filtered back projection (FBP) and four increasing percentages of ASIR (30%, 50%, 70%, and 90%). Image noise and contrast-to-noise ratio (CNR) were measured. Two musculoskeletal radiologists independently evaluated several anatomic structures and image quality parameters using a 4-point scale. They also jointly assessed acetabular labrum tears and articular cartilage lesions.

RESULTS

With decreasing radiation dose level, image noise statistically significantly increased (p=0.0009) and CNR statistically significantly decreased (p=0.001). We also found a statistically significant reduction in noise (p=0.0001) and increase in CNR (p≤0.003) with increasing percentage of ASIR; in addition, we noted statistically significant increases in image quality scores for the labrum and cartilage, subchondral bone, overall diagnostic quality (up to 50% ASIR), and subjective noise (p≤0.04), and statistically significant reductions for the trabecular bone and muscles (p≤0.03). Regardless of the radiation dose level, there were no statistically significant differences in the detection and characterization of labral tears (n=24; p=1) and cartilage lesions (n=40; p≥0.89) depending on the ASIR percentage.

CONCLUSION

The use of up to 50% ASIR in hip MDCT arthrography helps to reduce radiation dose by approximately 35-60%, while maintaining diagnostic image quality comparable to that of a regular-dose protocol using FBP.

Open repair of the triangular fibrocartilage complex from palmar aspect

Background Although foveal tears of the triangular fibrocartilage complex (TFCC) can be surgically reattached to the fovea via a dorsal approach, the foveal lesion is difficult to visualize from the dorsal side because the extensor carpi ulnaris (ECU) sheath floor and the superficial dorsal limb of the radioulnar ligament hinders the view of the fovea. Materials and Methods Twenty-one patients with foveal tears were treated by an open repair method from the palmar aspect. Pain, instability, motion, and grip strength were evaluated after a mean follow-up period of 26 months, and each patient was rated according to the Mayo Modified Wrist Score (MMWS). Description of Technique A 4-cm skin incision is made on the palmar aspect of the ulnar fovea. The ulnar fovea is exposed through a transverse capsulotomy of the distal radioulnar joint. The distal aspect of the TFCC is also exposed between the ECU tendon sheath and the ulnotriquetral ligament. After curettage of the scar tissue in the fovea, the deep palmar and dorsal limbs of the TFCC are sutured back to the fovea using a suture anchor technique. Results Foveal TFCC tears could be repaired via a palmar surgical approach without violating the floor of the ECU tendon sheath and the superficial dorsal limb. Excellent results were achieved in 18 patients, and a good result was achieved in three. Conclusions Our result compared favorably with those reported for dorsal approach. The palmar surgical approach facilitates the inspection and repair of the TFCC foveal tears. Level of Evidence IV.

Morphological Characteristics of the Repaired Labrum According to Glenoid Location and Its Clinical Relevance After Arthroscopic Bankart Repair: Postoperative Evaluation With Computed Tomography Arthrography

BACKGROUND

There have been no studies on the postoperative morphological characteristics of the restored labrum at different glenoid locations and its clinical relevance after arthroscopic Bankart repair with suture anchors.

PURPOSE

To analyze the morphological characteristics of the restored labrum at different locations of the glenoid and their relevance to clinical outcomes as well as affecting factors and to trace the inserted suture anchors after arthroscopic Bankart repair using computed tomography arthrography (CTA).

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A total of 46 patients (mean age, 26.5 ± 6.8 years) who underwent arthroscopic Bankart repair with absorbable suture anchors were enrolled in this study. Patients underwent CTA preoperatively and 6 months postoperatively as well as functional outcome evaluation preoperatively and at the last follow-up (>24 months) with the Rowe score and visual analog scale for pain. Labral height and width were measured on conventional axial CTA images at the 3-, 4-, and 5-o'clock positions twice by 2 raters. The postoperative measurements were also compared with those of the healthy anterior labrum, acquired from the same CTA examination of 32 consecutive patients (mean age, 26.5 ± 8.5 years) with superior labral lesions in the same study period. The postoperative difference in the measurements and between clock positions, and the relationship between the measurements and the clinical factors and functional outcomes, were evaluated. In addition, the locations of all suture anchors were traced on each CTA image, and outcomes according to the locations of the most inferior suture anchors were assessed.

RESULTS

The interobserver and intraobserver reliabilities of measurements at each location were excellent (Pearson correlation coefficient = 0.773-0.988). Of the 46 patients, 2 (4.35%) had redislocations after surgery. Postoperative labral height and width were significantly increased at all locations (all P < .001) up to a level similar to the healthy anterior labrum, with significantly larger values at the inferior location compared with the superior location (all P < .05). Patients who had a greater frequency of dislocations before surgery showed a lower postoperative labral height at the 5-o'clock position (P = .012), and this correlated with postoperative instability and poor functional outcomes by the Rowe score (P = .036). In most patients (41/46; 89.1%), the tips of the lowest suture anchors perforated the far cortex, and these anchors were mostly located below the 5-o'clock position (32/41; 78.0%). However, perforation of the far cortex did not affect functional outcomes.

CONCLUSION

Surgeons should be cautious of restoring labral height at the inferior glenoid location for successful arthroscopic Bankart repair. In addition, attention should be given to inserting the lowest suture anchor regardless of clinical significance.

MR arthrography of the shoulder: optimizing pulse sequence protocols for the evaluation of cartilage and labrum

OBJECTIVES

To compare axial T1weighted fat-saturated (T1w fs) and T1w non-fs sequences, and coronal T1w-fs and T2w-fs sequences, for evaluation of cartilage and labrum using CT arthrography (CTA) as the reference.

METHODS

Patients had MR arthrography (MRA) and CTA of the shoulder on the same day. Cartilage was assessed for superficial and full thickness focal and diffuse damage. Labral lesions were graded for Bankart variants and SLAP lesions. CTA images were read for the same features. The diagnostic performance of MRA including area under the curve (AUC) was evaluated against CTA.

RESULTS

When comparing axial sequences, the diagnostic performance for cartilage lesion detection on T1w non-fs was 61.9% (sensitivity) 93.6% (specificity) and 89.5% (accuracy) with AUC 0.782, while that for T1w fs was 61.9%, 94.0%, 89.8% and 0.783. For labral assessment, it was 89.1%, 93.0%, 91.4% and 0.919 for T1w non-fs, and 89.9%, 94.0%, 92.6% and 0.922 for T1w fs. Comparing coronal sequences, diagnostic performance for cartilage was 42.5%, 97.5%, 89.8% and 0.702 for T1w fs, and 38.4%, 98.7%, 90.2%, and 0.686 for T2w fs. For the labrum it was 85.1%, 87.5%, 86.2%, and 0.868 for T1w fs, and 75.7%, 97.5%, 80.8% and 0.816 for T2w fs.

CONCLUSIONS

Axial T1w fs and T1w non-fs sequences are comparable in their ability to diagnose cartilage and labral lesions. Coronal T1w fs sequence offers slightly higher sensitivity but slightly lower specificity than T2w fs sequence for diagnosis of cartilage and labral lesions.