CT changes after trochleoplasty for symptomatic trochlear dysplasia

Trochlear dysplasia is an important risk factor for patellar instability. Because of a decreased trochlear depth in combination with a low lateral femoral condyle, the patella cannot engage properly in the trochlea. Trochleoplasty is a surgical procedure, which strives to correct such bony abnormalities. The aim of this study was to describe morphological features of trochlear dysplasia and the corrective changes after trochleoplasty on CT scan. The study group consists of 17 knees with trochlear dysplasia having undergone trochleoplasty for recurrent patellofemoral dislocation at a mean age of 22.4 years. The evaluation consisted in pre- and postoperative measurements on the proximal and distal trochlea on transverse CT scans in order to determine the morphological features. We measured the transverse position and depth of the trochlear groove, the transverse position of the patella, the ratio between the posterior patellar edge and the trochlear groove, the lateral patellar inclination angle, the sulcus angle, and the lateral trochlear slope. The trochlear groove lateralised a mean of 6.1 mm in the proximal aspect and 2.5 mm in the distal aspect of the trochlea, while the patella medialised a mean of 5 mm. Preoperatively the patella was lateral in relation to the trochlear groove in 13 cases, neutral in two cases, and medial in two cases. Postoperatively it was lateral in four cases, in neutral position in seven cases, and medialised in six cases, referenced to the trochlear groove. The trochlear depth increased from 0 to 5.9 mm postoperatively in the proximal aspect of the trochlea, and from 5.5 to 8.3 mm postoperatively in the distal trochlea. The lateral patellar inclination angle decreased from a mean of 21.9° to a mean of 7.8°. The sulcus angle decreased from a mean of 172.1° to a mean of 133° in the proximal trochlea and from a mean of 141.9° to a mean of 121.7° in the distal trochlea. The lateral trochlear slope changed from 2.8° to 22.7° in the proximal and from 14.9° to 26.9° in the distal part of the trochlea. In the CT scan patients with trochlear dysplasia demonstrated a poor depth, or even a flat or convex trochlea with a greater sulcus and lateral trochlear slope angle, a lateralised patella to the trochlear groove with poor congruency, and a greater lateral patellar inclination angle. Trochleoplasty can correct the pathological features of trochlear dysplasia by surgically creating more normal anatomy. The goal of this surgical procedure is to steepen and lateralise the trochlear groove for a better engagement of the patella.     

Factors of patellar instability: An anatomic radiographic study

We analyzed the radiographs and computed tomography (CT) scans of 143 knees operated on for symptomatic patellar instability and 67 contralateral asymptomatic knees, togcther with 190 control knee radiographs and 27 control knee scans, to determine the factors affecting patellar instability. Four factors were relevant in knees with symptomatic patellar instability: (1)Trochlear dysplasia (85%), as defined by the crossing sign (96%) and quantitatively experessed by the trochlear bump, pathological above 3 mm or more (66%), and the trochlear depth, pathologic at 4 mm or less. (2)Quadriceps dysplasia (83%), defined as present when the patellar tilt in extension is more than 20% on the CT scans. (3)Patella alta (Caton-Deschamps) index greater than or equal to 1.2 (24%). (4)Tibial tuberosity-trochlear groove, pathological when greater than or equal to 20 mm (56%). The factors appeared in only 3%–6.5% of the control knees. The etiology of patellar instability is multifactorial. Determination of the factors permits an effective elective therapeutic plan which aims at correcting the anomalies present.     

Patellar dislocations in children, adolescents and adults: A comparative MRI study of medial patellofemoral ligament injury patterns and trochlear groove anatomy

Purpose

The first aim was to compare medial patellofemoral ligament injury patterns in children and adolescents after first-time lateral patellar dislocations with the injury patterns in adults. The second aim was to evaluate the trochlear groove anatomy at different developmental stages of the growing knee joint.

Materials and methods

Knee magnetic resonance (MR) images were collected from 22 patients after first-time patellar dislocations. The patients were aged 14.2 years (a range of 11-15 years). The injury pattern of the medial patellofemoral ligament was analysed, and trochlear dysplasia was evaluated with regard to sulcus angle, trochlear depth and trochlear asymmetry. The control data consisted of MR images from 21 adult patients who were treated for first-time lateral patellar dislocation.

Results

After patellar dislocation, injury to the medial patellofemoral ligament was found in 90.2% of the children and in 100% of the adult patients. Injury patterns of the medial patellofemoral ligament were similar between the study group and the control group with regard to injury at the patellar attachment site (Type I), to the midsubstance (Type II) and to injury at the femoral origin (Type III) (all p > 0.05). Combined lesions (Type IV) were significantly less frequently observed in adults when compared to the study group (p = 0.02). The magnitude of trochlear dysplasia was similar in children, adolescents and adults with regard to all three of the measured parameter-values (all p > 0.05). In addition, the articular cartilage had a significant effect on the distal femur geometry in both paediatrics and adults.

Conclusion

First, the data from our study indicated that the paediatric medial patellofemoral ligament injury patterns, as seen on MR images, were similar to those in adults. Second, the trochlear groove anatomy and the magnitude of trochlear dysplasia, respectively, did not differ between adults and paediatrics with patellar instability. Thus, physicians are confronted with similar anatomical risk factors and similar injuries to the medial soft-tissue restraints in children when compared to adults with patellar instability.     

Myocardial viability assessment using nuclear imaging

Myocardial assessment continues to be an issue in patients with coronary artery disease and left ventricular dysfunction. Nuclear imaging has long played an important role in this field. In particular, PET imaging using 18F-fluorodeoxyglucose is regarded as the metabolic gold standard of tissue viability, which has been supported by a wide clinical experience. Viability assessment using SPECT techniques has gained more wide-spread clinical acceptance than PET, because it is more widely available at lower cost. Moreover, technical advances in SPECT technology such as gated-SPECT further improve the diagnostic accuracy of the test. However, other imaging techniques such as dobutamine echocardiography have recently emerged as competitors to nuclear imaging. It is also important to note that they sometimes may work in a complementary fashion to nuclear imaging, indicating that an appropriate use of these techniques may significantly improve their overall accuracy. In keeping these circumstances in mind, further efforts are necessary to further improve the diagnostic performance of nuclear imaging as a reliable viability test.     

Impact of Chronic Lateral Ankle Instability with Lateral Collateral Ligament Injuries on Biochemical Alterations in the Cartilage of the Subtalar and Midtarsal Joints Based on MRI T2 Mapping

ObjectiveTo quantitatively assess biochemical alterations in the cartilage of the subtalar and midtarsal joints in chronic lateral ankle instability (CLAI) patients with isolated anterior talofibular ligament (ATFL) injuries and combined calcaneofibular ligament (CFL) injuries using MRI T2 mapping.Materials and MethodsThis study was performed according to regulations of the Committee for Human Research at our institution, and written informed consent was obtained from all participants. Forty CLAI patients (26 with isolated ATFL injuries and 14 with combined ATFL and CFL injuries) and 25 healthy subjects were recruited for this study. All participants underwent MRI scans with T2 mapping. Patients were assessed with the American Orthopedic Foot and Ankle Society (AOFAS) rating system. The subtalar and midtarsal joints were segmented into 14 cartilage subregions. The T2 value of each subregion was measured from T2 mapping images. Data were analyzed with ANOVA, the Student''s t test, and Pearson''s correlation coefficient.ResultsT2 values of most subregions of the subtalar joint and the calcaneal facet of the calcaneocuboid joint in CLAI patients with combined CFL injuries were higher than those in healthy controls (all p < 0.05). However, there were no significant differences in T2 values in subtalar and midtarsal joints between patients with isolated ATFL injuries and healthy controls (all p > 0.05). Moreover, T2 values of the medial talar subregions of the posterior subtalar joint in patients with combined CFL injuries showed negative correlations with the AOFAS scores (r = −0.687, p = 0.007; r = −0.609, p = 0.021, respectively).ConclusionCLAI with combined CFL injuries can lead to cartilage degeneration in subtalar and calcaneocuboid joints, while an isolated ATFL injury might not have a significant impact on the cartilage in these joints.     

Comparison of MRI T2 Relaxation Changes of Knee Articular Cartilage before and after Running between Young and Old Amateur Athletes

ObjectiveTo compare changes in T2 relaxation on magnetic resonance (MR) images of knee articular cartilage in younger and older amateur athletes before and after running.ResultsChanges in global cartilage T2 values after running did not differ significantly between the age groups. In terms of the depth variation, relatively higher T2 values in the older group than in the younger group were observed mainly in the superficial layers of the femoral and tibial cartilage (p < 0.05).ConclusionAge-related cartilage changes may occur mainly in the superficial layer of cartilage where collagen matrix degeneration is primarily initiated. However, no trend is observed regarding a global T2 changes between the younger and older age groups in response to exercise.     

~(201)Tl再注射心肌显像和再注射后延迟显像检测心肌存活的对比研究

为了解２０１Ｔｌ再注射及再注射后延迟显像对心肌存活的检测能力，对６２例心肌梗塞患者进行了２０１Ｔｌ运动、３～５小时再分布、２０１Ｔｌ再注射后１６～３５分钟及再注射后１２～１９小时延迟心肌断层显像。１５例患者于显像后行经皮冠状动脉腔内成形术（ＰＴＣＡ），并于ＰＴＣＡ后重复运动再分布心肌显像。结果：６２例患者运动再分布显像共有１２６个不可逆缺损节段，其中４８个节段再注射后１６～３５分钟出现放射性填充，心肌存活检出率为３８１％（４８／１２６）；５１个节段再注射后延迟显像出现再分布，心肌存活检出率为４０５％（５１／１２６）。两种显像方案的检出率差异无显著性（χ２＝０１６，Ｐ＞００５），但两者结合６２个节段示有放射性填充，心肌存活检出率可提高到４９２％（６２／１２６）。１５例患者ＰＴＣＡ前共检出１７个心肌存活节段，术后１２个节段２０１Ｔｌ灌注改善，阳性预测率为７０６％；ＰＴＣＡ前检出１１个梗塞节段，术后９个节段２０１Ｔｌ摄取无改善，阴性预测率为８１８％。结果表明：２０１Ｔｌ再注射与延迟显像心肌存活检出率无明显差别，但两者联合应用可提高检出率。     

Twenty-four-hour Tl-201 delayed scan underestimates myocardial viability in patients with acute myocardial infarction after percutaneous transluminal coronary angioplasty

BACKGROUND: Myocardial viability in area at risk of acute myocardial infarction (AMI) after reperfusion therapy may be underestimated by the 24-hour images due to reverse redistribution (r-RD). METHODS: Subjects were 37 AMI patients in whom Tc-99m pyrophosphate (PYP)/Tl-201 dual-isotope SPECT was positive. The 24-hour delayed scan was performed with only a Tl window. One month later, follow up rest Tl SPECT was performed to evaluate myocardial viability. In early (at PYP/Tl-201 dual-isotope SPECT), 24-hour, and one month follow up Tl studies, Tl uptake in the area of AMI was scored into four grades: 3 as normal to 0 as severely reduced. The scores were evaluated. RESULTS: Among the 37 AMI lesions, there were 16 r-RD, 3 RD, 16 fixed defect (FD) and 2 normal (positive PYP and normal Tl). Mean Tl scores were early; 1.4 +/- 1.1, 24-hr; 0.9 +/- 0.9 and one month; 1.3 +/- 1.1. The 24-hour Tl score was lower than the early and one month Tl scores (p < 0.01). CONCLUSION: Reverse redistribution is frequently observed in an area at risk where PYP SPECT was positive. Nuclear medicine physicians should be aware of the existence of frequent r-RD in Tl scan to avoid the underestimation of myocardial viability in the acute phase after PTCA.     

Cartilage lesions of the glenohumeral joint: diagnostic effectiveness of multidetector spiral CT arthrography and comparison with arthroscopy

This study assessed the diagnostic effectiveness of multidetector spiral CT arthrography (MDCTa) in detecting hyaline cartilage abnormalities of the shoulder joint, with correlation to arthroscopy. Shoulder MDCTa images prospectively obtained in 22 consecutive patients (mean age, 50 years; age range, 23–74 years; 12 female, 10 male) were evaluated for glenohumeral cartilage lesions. Two musculoskeletal radiologists independently analysed the cartilage surfaces of the humeral head and of the glenoid fossa in nine anatomical surface areas. Observations of MDCTa were compared to arthroscopic findings. The sensitivity and specificity of MDCTa for grade 2 (substance loss <50%) or higher and grade 3 (substance loss ≥50%) or higher cartilage lesions, the Spearman correlation coefficient between arthrographic and arthroscopic grading, and K statistics for assessing Intra and Interobserver reproducibility were determined. At MDCTa, sensitivities and specificities ranged between 80% and 94% for the detection of grade 2 or higher cartilage lesions, and between 88% and 98% for the detection of grade 3 or higher cartilage lesions. Spearman correlation coefficients between MDCTa and arthroscopic grading of articular surfaces ranged between 0.532 and 0.651. Interobserver agreement was moderate for grading all articular surfaces (κ = 0.457), but substantial to almost perfect for detecting lesions with substance loss (κ, 0.618–0.876). In conclusion, MDCTa is accurate for the study of cartilage surface in the entire shoulder joint. This technique may beneficially impact patient’s management by means of selecting the proper treatment approach.     

Imaging patellar complications after knee arthroplasty

The purpose of this study is to describe complications affecting the patella in patients with total or partial knee arthroplasty. We respectively analysed plain-film radiographs, as well as ultrasound images when acquired, in a consecutive series of 1272 patients. The mean interval from knee replacement to patellar complications was 5 years and 7 months (range, 5 months to 14 years). The complications described include fracture, instability, dislocation or luxation, necrosis of the patella, infection of the patella, erosion of the patella, patellar impingement on the prosthesis and patellar or quadricipital tendon tear. We discuss the pathological imaging findings in the patella and their differential diagnosis after knee arthroplasty. Patellar complications after knee arthroplasty are uncommon but often potentially serious.     

Technetium 99m-HL-91: A potential new marker of myocardial viability assessed by nuclear imaging early after reperfusion

Objective  99mTc-HL-91 (Prognox) is a potential new hypoxia-avid myocardial imaging agent. The purpose of this study was to determine whether this tracer would demonstrate increased activity in nonviable myocardium in vivo. Methods and Results  A 3-hour left circumflex artery (LCx) occlusion was followed by 1 hour of reperfusion, injection of 99mTc-HL-91 (185 MBq), and 2 hours of gamma camera imaging in 6 open-chest canine experiments. Microspheres were injected during baseline, at occlusion, at the time of tracer injection, and at the end of the experiment. After the animals were killed, heart slices were imaged. Blood flow and tracer activity were determined by well counting. Mean infarct size was 19.2%±2.2% (SEM). All six dogs demonstrated no increased 99mTc-HL-91 myocardial activity other than small foci on in vivo and ex vivo gamma camera images. The mean large region of interest (ROI)-determined LCx/LAD (left anterior descending) ratio was 1.10±0.03 in vivo, and 1.0±0.02 ex vivo. Mean clearance curves from LCx and LAD ROI were not significantly different, and 2-hour retention was 15.2%±2.1% for the LCx and 18.6%±2.7% for the LAD (p=NS). ROI clearance curves demonstrated biexponential clearance over the first hour and linear clearance over the second hour. Myocardial blood flow (microspheres) versus well-counted tracer uptake curves were linear with near-zero slopes for viable tissue, non-viable tissue, and mosaic tissue. Blood clearance was triexponential with a 2-hour retention of 7.8%±1.1%. Conclusions  In contrast to viable ischemic tissue, normal and nonviable myocardium demonstrate similar 99mTc-HL-91 uptake and retention kinetics. This agent warrants further clinical studies in situations where there is a need to differentiate ischemic viable from nonviable myocardium. Supported in part by Nycomed Amersham p/c, Buckinghamshire, UK