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Nuclear Medicine Imaging of Ankle Injuries
Abstract
Given the complex anatomy and function of the ankle, the management of chronic pathologies remains a challenge particularly in high-demand groups of patients such as athletes. Besides conventional X-rays for standard radiologic examination and MRI, nuclear imaging, mostly SPECT/CT, is becoming more and more important. In the last years, SPECT/CT has almost extruded simple scintigraphic bone scans in evaluation of complex bony hindfoot disorders and has renewed the interest in nuclear imaging for ankle pathologies. This is mainly due to its unique combination of detailed morphologic information from the CT and the clearly localised metabolic information of each specifi c bone or even each specifi c region of particular bones from the SPECT. This ability makes SPECT/CT a new important tool which adds substantial information to the data achievable from MRI examination. However, there is currently only scarce evidence about SPECT/CT around the ankle. This chapter summarises the current scientifi c knowledge, adds clinical examples and shows future directions to be elucidated to enhance the use of SPECT/CT around the ankle.
Background
Ankle joint, as one of the important joints supporting the weight of human body, is vulnerable to injury in daily physical exercise and sports because of its special growth location and anatomical composition. The rehabilitation period of traumatic ankle is relatively long, especially in the later period of recovery. In order to relieve the clinical symptoms such as swelling and pain caused by ankle trauma, the rehabilitation of the ankle should be actively carried out by means of rehabilitation equipment. Thus, the ankle rehabilitation cycle can be minimized largely and the rehabilitation efficiency can be improved greatly.
Objective
Through the summary of the latest literature on ankle rehabilitation devices, readers will be familiar with the research progress and difficulties in this field, and the reference for the follow-up study in this direction is provided.
Method
The structural characteristics and applications of the ankle rehabilitation devices are introduced in the paper. The latest patents and articles related to ankle rehabilitation device are compared and analyzed.
Results
The ankle rehabilitation devices are classified according to the structure characteristics, driving mode and training function. The advantages and disadvantages of various devices are pointed out, and the future development direction of this research field is predicted.
Conclusion
Studies show that remarkable improvements have been achieved on the ankle rehabilitation equipment. In the future, the structural optimization, new materials, control strategy, new type actuators, and rehabilitation evaluation of ankle rehabilitation devices should be further studied.
Atypical femoral fractures (AFF), although rare, are recognized more often during the last decade. They are located in the subtrochanteric region or the femoral shaft, may be bilateral, can evolve to complete fractures after bone overload or minimal trauma and have specific radiological features. The complete fractures have horizontal or slightly oblique configuration accompanied by a medial spike, are non-comminuted, and extend to both cortices. There is also generalized cortical thickening of femoral shaft. Newer evidence suggests that AFF are stress or insufficiency fractures, possibly associated with long-term use of bisphoshonates (BP). AFF can also occur in oncologic patients referred for bone scintigraphy and, in such a case, they should be differentiated from bone metastases. We present here a case with bilateral AFF with metachronous appearance in a female patient with a history of breast cancer and osteoporosis. The first AFF had been depicted on bone scintigraphy 3 years before a complete fracture occurred at this site, but the finding was overlooked. A second bone scan performed shortly after the fracture in order to exclude underlying bone metastases disclosed an additional unsuspected incomplete AFF in the contralateral femur, which was confirmed by radiography. In conclusion, oncologists should consider other causes of bone pain besides bone metastatic disease, and physicians interpreting whole body bone scans of oncologic patients should be aware of the entity of AFF, in order to avoid false positive results and provide early information about an impending complete AFF.
Magnetic resonance imaging (MRI) is the current standard in noninvasive diagnostics of osteochondral lesions (OCLs) of the talus. Single-photon emission computed tomography-computed tomography (SPECT-CT) is a new technique that displays different imaging qualities. The influence of the aforementioned diagnostic information on treatment decision making in talar OCLs is not known.
The aim of the study was to evaluate SPECT-CT in comparison with MRI for image interpretation and decision making in OCLs of the talus.
Case series; Level of evidence, 4.
Magnetic resonance imaging and SPECT-CT of 25 patients (average age, 32 years; range, 18-69 years) were analyzed by 3 independent orthopaedic surgeons blinded to the study. Raters had to analyze images for predefined criteria of cartilage, subchondral bone plate, and subchondral bone, including bone marrow edema on MRI and scintigraphic activity on SPECT-CT. For MRI alone, SPECT-CT alone, and their combination, the treatment decision had to be defined.
In comparison with MRI alone, treatment decision making changed in 48% of the cases with SPECT-CT alone and 52% with SPECT-CT and MRI combined. While cartilage showed good correlation for interpretation between MRI and SPECT-CT, the subchondral bone plate and subchondral bone showed substantial differences. Poor intrarater correlation highlighted the different information provided by the 2 imaging techniques. Poor interrater correlation showed a high heterogeneity in the treatment decision making of OCLs.
Compared with MRI, SPECT-CT provides additional information and influences the decision making of OCL treatment. For thorough diagnostic evaluation in OCLs, performing both MRI and SPECT-CT is recommended. Further clinical investigation is needed to see if SPECT-CT in addition to MRI results in improved treatment outcomes.
Osteochondral lesions are frequently seen in athletes after ankle injuries. At this time, osteochondral autologous transplantation (OATS, mosaicplasty) is the only surgical treatment that replaces the entire osteochondral unit in symptomatic lesions.
To evaluate the clinical and radiological midterm to long-term outcome of ankles treated with knee-to-ankle mosaicplasty.
Case series; Level of evidence, 4.
Clinical evaluation consisted of patient satisfaction, pain evaluation (visual analog scale [VAS]), American Orthopaedic Foot and Ankle Society (AOFAS) ankle score, sports activity score, range of motion, the radiological evaluation of magnetic resonance imaging (MRI), and single photon emission computed tomography-computed tomography (SPECT-CT) analysis of both the ankle and the knee joint.
Twelve of 21 patients (mean age, 43 years; male, 8; female, 4) were available for latest follow-up (mean, 72 months). At follow-up, patients reported a satisfaction rate of good to excellent in 92% (n = 11) and poor in 8% (n = 1). The average VAS pain score was 3.9 (preoperative, 5.9; P = .02), AOFAS ankle score significantly increased from 45.9 to 80.2 points (P < .0001), sports activity score remained significantly decreased with 1.25 (preinjury level, 2.3; P = .035), and ankle dorsiflexion was significantly reduced (P = .003). Knee pain was reported in 6 patients (50%). Radiologically, recurrent lesions were found in 10 of 10 cases (100%) and some degree of cartilage degeneration and discontinuity of the subchondral bone plate in 100%.
Indications for mosaicplasty with a plug transfer from the knee to the talus must be considered carefully, as at midterm, moderate outcome and considerable donor-site morbidity may be found.
The precise localisation of osteoarthritic changes is crucial for selective surgical treatment. Single photon-emission CT-CT (SPECT-CT) combines both morphological and biological information. We hypothesised that SPECT-CT increased the intra- and interobserver reliability to localise increased uptake compared with traditional evaluation of CT and bone scanning together. We evaluated 20 consecutive patients with pain of uncertain origin in the foot and ankle by radiography and SPECT-CT, available as fused SPECT-CT, and by separate bone scanning and CT. Five observers assessed the presence or absence of arthritis. The images were blinded and randomly ordered. They were evaluated twice at an interval of six weeks. Kappa and multirater kappa values were calculated.
The mean intraobserver reliability for SPECT-CT was excellent (κ = 0.86; 95% CI 0.81 to 0.88) and significantly higher than that for CT and bone scanning together. SPECT-CT had significantly higher interobserver agreement, especially when evaluating the naviculocuneiform and tarsometatarsal joints.
SPECT-CT is useful in localising active arthritis especially in areas where the number and configuration of joints are complex.
This review article focuses on occurrence, imaging, and differential diagnosis of insufficiency fractures. Prevalence and the most common sites of insufficiency fractures and their clinical implications are discussed. Insufficiency fractures are due to normal stress exerted on weakened bone. Most commonly postmenopausal osteoporosis is the cause for insufficiency fractures. Additional conditions affecting bone turnover include osteomalacia, chronic renal failure, and high-dose corticosteroid therapy. It is a challenge for the radiologist to detect and diagnose insufficiency fractures as well as to differentiate them from malignant fractures. Radiographs are the basic modality used for screening of insufficiency fractures, yet depending on the location of the fractures, sensitivity is limited. Magnetic resonance imaging is a very sensitive tool to visualize bone marrow abnormalities associated with insufficiency fractures and allows differentiation of benign versus malignant fractures. Thin section multidetector computed tomography (CT) depicts subtle fracture lines allowing direct visualization of cortical and trabecular bone. Dedicated Mikro-CTs (Xtreme-CT) can detect subtle fractures reaching an in-plane resolution of 80 μm. Bone scintigraphy still plays a role in detecting fractures, with good sensitivity but unsatisfactory specificity. Positron emission tomography-CT with hybrid-scanners has been the upcoming modality for the differentiation of benign from malignant fractures. Bone densitometry and clinical fracture history may determine the future risk of possible insufficiency fractures.
We hypothesized that bone SPECT combined with multiplanar reconstructed CT can identify and target the pain-inducing focus in the foot and can be used to successfully guide anaesthetic infiltrations. Therefore we prospectively investigated feasibility and predictive value of bone SPECT/CT for image guided diagnostic infiltrations in patients with chronic foot pain.
All patients received a standardized bone SPECT/CT of both feet. The scintigraphically most active structures were subsequently infiltrated with local anaesthetics under CT-guidance. The pre- and post-infiltration pain intensity was measured using the visual analogue scale (VAS). Then, we assessed (i) the agreement on pain originating structures determined by standard clinical assessment versus SPECT/CT and (ii) the predictive value of SPECT-CT in groups with and without agreement.
27 of 30 participants reported a pain reduction on VAS of 50% or more, resulting in a response rate of 90%. When assessing the agreement on pain initiating structures determined by standard clinical assessment versus SPECT/CT, we found a disagreement in 16 of 30 (53%) cases. Particularly, disagreement appeared in all 9 participants with symptoms located in the mid-foot (100%). In participants with hind-foot pathology, disagreement was found in 7 of 21 cases (33%).
The present study shows the feasibility of 99mTc-DPD-SPECT/CT guided infiltration of osseous structures of patients with chronic foot pain. 99mTc-DPD-SPECT/CT had a higher predictive value on the clinical outcome than the clinical assessment. In the clinical setting 99mTc-DPD-SPECT/CT might overrule the clinical assessment in case of disagreement on the target lesion.
Disorders of the ankle and foot are common and given the complex anatomy and function of the foot, they present a significant clinical challenge. Imaging plays a crucial role in the management of these patients, with multiple imaging options available to the clinician. The American College of radiology has set the appropriateness criteria for the use of the available investigating modalities in the management of foot and ankle pathologies. These are broadly classified into anatomical and functional imaging modalities. Recently, single-photon emission computed tomography and/or computed tomography scanners, which can elegantly combine functional and anatomical images have been introduced, promising an exciting and important development. This review describes our clinical experience with single-photon emission computed tomography and/or computed tomography and discusses potential applications of these techniques.
Identifying factors associated with favorable or unfavorable outcomes would provide patients with accurate expectations of the arthroscopic marrow stimulation techniques.
To investigate the prognostic significance and optimal measures of defect size in osteochondral lesion of the talus as treated with arthroscopy.
A critical, or threshold, defect size may exist at which clinical outcomes become poor in the treatment of osteochondral lesion of the talus.
Cohort study; Level of evidence, 3.
In sum, 120 ankles underwent arthroscopic marrow stimulation treatment for osteochondral lesion of the talus and were evaluated for prognostic factors. Clinical failure was defined as patients' having osteochondral transplantation or an American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot Scale score less than 80. Linear regression analysis and the Kaplan-Meier method were used to identify optimal cutoff values of defect size.
Eight ankles (6.7%) required osteochondral transplantation, and 22 ankles (18.4%) were considered failures because of AOFAS scores less than 80, which indicated fair or poor results. Linear regression analysis showed a high prognostic significance of defect area and suggested a cutoff defect size of 150 mm(2) for the optimum identification of poor clinical outcomes (P < .001). Only 10 of 95 ankles (10.5%) with a defect area <150 mm(2) showed clinical failure, whereas in patients with an area >or=150 mm(2), the clinical failure rate was significantly higher (80%, 20/25). There was no association between outcome and the patient's age, duration of symptoms, trauma, associated lesions, and location of lesions (P > .05).
Initial defect size is an important and easily obtainable prognostic factor in osteochondral lesions of the talus and so may serve as a basis for preoperative surgical decisions. A cutoff point exists regarding the risk of clinical failure at a defect area of approximately 150 mm(2) as calculated from magnetic resonance imaging.
The combined single-photon emission computed tomography and conventional computed tomography (SPECT/CT) technique has increased the sensitivity and specificity of bone scans. We examined the value of using SPECT/CT for the assessment of coronal plane hindfoot deformities. Twenty-seven patients with varus (11 patients) or valgus (16 patients) malalignment of the hindfoot were assessed using radiography, conventional CT, bone scintigraphy, and SPECT/CT. The amount of deformity, stage of osteoarthritis, and level of activation on bone scans and SPECT/CT were measured. Activation was assessed in 12 regions of interest. The stage of osteoarthritis seen on plain radiographs correlated significantly with the level of activation detected on bone scans (p < 0.05). No correlation was observed between the amount of deformation and activity, and between bone scan activation and signs of osteoarthritis on CT scans. The varus malaligned ankles showed higher radioisotope uptake in the medial areas, while the valgus malaligned ankles showed increased uptake in the lateral areas (p < 0.05). SPECT/CT may be a valuable tool for the assessment and staging of osteoarthritis. Our findings underline the adverse effects of coronal plane deformity of the hindfoot. In addition, results from this study provide useful information for future basic research on coronal plane deformity of the hindfoot and for determining appropriate surgical approaches.
The objective of this study was to correlate chronic medial knee pain at rest and during exercise with bone scintigraphic uptake, bone marrow edema pattern (BMEP), cartilage lesions, meniscal tears, and collateral ligament pathologies on magnetic resonance MR imaging (MRI).
Fifty consecutive patients with chronic medial knee pain seen at our institute were included in our study. Pain level at rest and during exercise was assessed using a visual analog scale (VAS). On MR images, BMEP volume was measured, and the integrity of femoro-tibial cartilage, medial meniscus, and medial collateral ligament (MCL) were assessed. Semiquantitative scintigraphic tracer uptake was measured. Multivariate linear regression analysis was performed.
At the day of examination, 40 patients reported medial knee pain at rest, 49 when climbing stairs (at rest mean VAS 33 mm, range 0-80 mm; climbing stairs mean VAS, 60 mm, range 20-100 mm). Bone scintigraphy showed increased tracer uptake in 36 patients (uptake factor, average 3.7, range 2.4-18.0). MRI showed BMEP in 31 studies (mean volume, 4,070 mm(3); range, 1,200-39,200 mm(3)). All patients with BMEP had abnormal bone scintigraphy. Ten percent of patients with pain at rest and 8% of patients with pain during exercise showed no BMEP but tracer uptake in scintigraphy. Tracer uptake and signal change around MCL predicted pain at rest significantly (tracer uptake p = 0.004; MCL signal changes p = 0.002). Only MCL signal changes predicted pain during exercise significantly (p = 0.001).
In chronic medial knee pain, increased tracer uptake in bone scintigraphy is more sensitive for medial knee pain than BMEP on MRI. Pain levels at rest and during exercise correlate with signal changes in and around the MCL.