Utility of brain imaging in pediatric patients with a suspected accidental spinal injury but no brain injury-related symptoms.

PURPOSE: Imaging is the gold standard in diagnosing traumatic brain injury, but unnecessary scans should be avoided, especially in children and adolescents. Clinical decision-making rules often help to distinguish the patients who need imaging, but if spinal trauma is suspected, concomitant brain imaging is often conducted. Whether the co-occurrence of brain and spine injuries is high enough to justify head imaging in patients without symptoms suggesting brain injury is unknown. OBJECTIVE: This study aims to assess the diagnostic yield of brain MRI in pediatric patients with suspected or confirmed accidental spinal trauma but no potential brain injury symptoms. METHODS: We retrospectively reviewed the medical and imaging data of pediatric patients (under 18 years old) who have undergone concomitant MRI of the brain and spine because of acute spinal trauma in our emergency radiology department over a period of 8 years. We compared the brain MRI findings in patients with and without symptoms suggesting brain injury and contrasted spine and brain MRI findings. RESULTS: Of 179 patients (mean age 11.7 years, range 0-17), 137 had symptoms or clinical findings suggesting brain injury, and 42 did not. None of the patients without potential brain injury symptoms had traumatic findings in brain MRI. This finding also applied to patients with high-energy trauma (n = 47) and was unrelated to spinal MRI findings. CONCLUSION: Pediatric accidental trauma patients with suspected or confirmed spine trauma but no symptoms or clinical findings suggesting brain injury seem not to benefit from brain imaging.

Outcomes of Follow-up Imaging After Pediatric Spinal Trauma Confirmed With Magnetic Resonance Imaging.

BACKGROUND: Imaging plays a crucial role in the diagnostic workup of pediatric spinal trauma. Computed tomography and conventional radiographs are widely used as the primary imaging methods. Magnetic resonance imaging (MRI) is a radiation-free alternative with high sensitivity for bony and soft tissue injuries. There is no consensus on the optimal use of follow-up imaging in pediatric spinal trauma without immediate surgical treatment, especially if the injury is primarily confirmed with MRI. This study aimed to assess the diagnostic value of follow-up imaging after MRI-confirmed spinal trauma in children. METHODS: The medical records and the imaging data of children and adolescents with emergency spinal MRI and follow-up imaging over 8 years were retrospectively reviewed. The primary study outcome was the outcome of follow-up imaging and its effect on management. RESULTS: The study population consisted of 127 patients. The follow-up imaging did not alter the management in any patient with presumably stable injury in emergency MRI. Short-term follow-up imaging showed no clinically significant progression in thoracolumbar compression fractures. Flexion-extension radiographs had no additional value in cases with stable cervical spinal injury on emergency MRI. CONCLUSIONS: The clinical utility of short-term follow-up imaging is low in children with stable spinal injury on emergency MRI. LEVEL OF EVIDENCE: Level III-retrospective observational study.

Diagnostic yield of emergency MRI in non-traumatic headache.

PURPOSE: Non-traumatic headache is one of the most common neurological complaints in emergency departments. A relatively low diagnostic yield of magnetic resonance imaging (MRI) among outpatients has been previously reported, but studies of emergency patients are lacking. We sought to determine the diagnostic yield of emergency MRI among outpatients presenting to the emergency department with non-traumatic headache. METHODS: In this retrospective cohort study, we analyzed emergency MRI referrals in a tertiary hospital for non-traumatic headache over a five-year period. We recorded patient characteristics, relevant clinical information from the referrals, and imaging outcomes. RESULTS: In total, 696 emergency patients with non-traumatic headache underwent MRI, most within 24 h of presentation. Significant findings related to headache were found in 136 (20%) patients, and incidental findings in 22% of patients. In a multivariate model, the predisposing factors of the significant findings were age, smoking, nausea, and signs/symptoms of infection. The protective factors were numbness and history of migraine. A predictive clinical score reached only moderate performance. CONCLUSION: Although emergency MRI shows headache-related findings in one in five patients, accurate prediction modeling remains a challenge, even with statistically significant predictors and a large sample size.

Clinical outcome following magnetic resonance imaging as first-line imaging in low-impact pediatric spine trauma: a single-center retrospective observational study.

BACKGROUND: Pediatric spinal trauma is rare, but the consequences of a missed injury can be devastating. Medical imaging is often needed in addition to physical examination. Conventional radiographs are widely recommended, but their negative predictive value is limited. Computed tomography (CT) is more sensitive but has a higher radiation dose. Magnetic resonance imaging (MRI) has superior soft tissue contrast and lacks ionizing radiation, but it is more expensive and time-consuming. Thus, the debate regarding the most suitable imaging method is still ongoing. OBJECTIVE: This study examined the ability of MRI to exclude injuries requiring surgical treatment as a first-line imaging method in low-impact pediatric spine trauma. MATERIALS AND METHODS: We retrospectively reviewed the medical records and imaging data of children (under 18 years old) who had suspected spinal trauma and were scanned using MRI in our emergency radiology department over a period of 8 years. We assessed the ability of MRI to detect unstable injuries by searching for later occurrences of primarily missed injuries requiring surgery. RESULTS: Of 396 patients (median age 12 years, range 0-17), 114 (29%) had MRI findings suggesting an acute injury. Bony injuries were detected in 78 patients (20%) and ligamentous or other soft tissue injuries in 82 patients (21%). In the subgroup of 376 patients (median age 12 years, range 0-17) with at least 6 months of clinical follow-up, no missed injuries demanding surgical intervention or immobilization occurred after spinal MRI as  first-line imaging. No adverse events related to MRI or anesthesia occurred. CONCLUSION: MRI can detect injuries requiring surgical treatment as a first-line imaging method in suspected low-impact pediatric spinal trauma and is safe to use in this selected population.

Clinical and prognostic significance of emergency MRI findings in neck infections.

OBJECTIVES: Due to its superior soft-tissue contrast and ability to delineate abscesses, MRI has high diagnostic accuracy in neck infections. Whether MRI findings can predict the clinical course in these patients is unknown. The purpose of this study was to determine the clinical and prognostic significance of various MRI findings in emergency patients with acute neck infections. MATERIALS AND METHODS: We retrospectively reviewed the 3-T MRI findings of 371 patients with acute neck infections from a 5-year period in a single tertiary emergency radiology department. We correlated various MRI findings, including retropharyngeal (RPE) and mediastinal edema (ME) and abscess diameter, to clinical findings and outcomes, such as the need for intensive care unit (ICU) treatment and length of hospital stay (LOS). RESULTS: A total of 201 out of 371 patients (54%) with neck infections showed evidence of RPE, and 81 out of 314 patients (26%) had ME. Both RPE (OR = 9.5, p < 0.001) and ME (OR = 5.3, p < 0.001) were more prevalent among the patients who required ICU treatment than among those who did not. In a multivariate analysis, C-reactive protein (CRP) levels, RPE, and maximal abscess diameter were independent predictors of the need for ICU treatment, and CRP, ME, and maximal abscess diameter were independent predictors of LOS. CONCLUSION: In patients with an acute neck infection that requires emergency imaging, RPE, ME, and abscess diameter, as shown by MRI, are significant predictors of a more severe illness. KEY POINTS: • Two hundred one out of 371 patients (54%) with neck infection showed evidence of retropharyngeal edema (RPE), and 81 out of 314 patients (26%) had mediastinal edema (ME). • Maximal abscess diameter, RPE, and C-reactive protein (CRP) were independent predictors of the need for intensive care unit (ICU) treatment, and maximal abscess diameter, ME, and CRP were independent predictors of length of hospital stay. • Prognostic significance of MRI findings was evident also while controlling for CRP values.

Magnetic resonance imaging findings in pediatric neck infections-a comparison with adult patients.

BACKGROUND: Differences in the functioning of the immune system and the anatomical proportions of the neck between children and adults lead to different manifestations of deep neck infections. Magnetic resonance imaging (MRI) may serve as an alternative to computed tomography (CT) as the primary imaging modality. OBJECTIVE: To study characteristic MRI findings and the diagnostic accuracy of MRI in pediatric deep neck infections. MATERIALS AND METHODS: We retrospectively studied a cohort of pediatric patients who underwent a neck 3-tesla MRI study over a five-year period. Inclusion criteria were: 1) emergency MRI findings indicating an infection, 2) infection as the final clinical diagnosis, 3) diagnostic image quality verified by the radiologist reading the study and 4) age under 18 years. Patient record data, including surgery reports, were compared with the MRI findings. RESULTS: Data of 45 children were included and analysed. Compared to adults, children had a higher incidence of retropharyngeal infection and lymphadenitis, and a lower incidence of peritonsillar/parapharyngeal infection. MRI showed evidence of an abscess in 34 children. Of these 34 patients, 24 underwent surgery, which confirmed an abscess in 21 but no abscess in three patients. In addition, three patients underwent surgery without MRI evidence of abscess, and an abscess was found in one of these cases. The measures of diagnostic accuracy among the children were sensitivity 0.96, specificity 0.77, positive predictive value 0.89, negative predictive value 0.91 and accuracy 0.89. Compared with adults, children had lower C-reactive protein, but a similar proportion of them had an abscess, and abscess size and rate of surgery were similar. CONCLUSION: Despite the differences in the infection foci, emergency MRI in children had equal diagnostic accuracy to that in adults.

Emergency neck MRI: feasibility and diagnostic accuracy in cases of neck infection.

BACKGROUND: Computed tomography (CT) has traditionally been the first-line imaging method in neck emergencies such as deep neck infections. Due to superior soft-tissue contrast, magnetic resonance imaging (MRI) may be an alternative to CT, also in emergency situations. PURPOSE: To characterize the use of routine MRI in neck emergencies, with an emphasis on clinical feasibility and diagnostic accuracy in cases of neck infection. MATERIAL AND METHODS: We conducted a retrospective cohort study of all primary neck MRI scans performed using a 3-T MRI device during a five-year follow-up period in a tertiary emergency radiology department. Imaging data were compared with final clinical diagnosis and surgical findings as reference standards. RESULTS: The search identified 461 primary neck MRI scans, of which 334 (72%) were performed on the basis of clinical suspicion of infection. Radiological evidence of infection was observed in 95% of these scans, and at least one abscess was detected in 229 cases (72% of confirmed infection). MRI had an overall technical success rate of 95% and had high positive predictive value for both infection (0.98) and detection of abscess (0.95). CONCLUSION: We found that emergency neck MRI can be successfully performed on most patients, and that MRI detects neck infection with a high accuracy. These results suggest that MRI may be an alternative to CT as the first or only imaging modality in neck emergencies.

Operative versus conservative treatment of small, nontraumatic supraspinatus tears in patients older than 55 years: over 5-year follow-up of a randomized controlled trial.

BACKGROUND: Nontraumatic rotator cuff tear is a common shoulder problem that can be treated either conservatively or operatively. In the previous publications of the 1- and 2-year results of this trial, we found no significant between-group clinical differences. The aim of this study was to investigate the differences in mid-term clinical and radiologic outcomes in patients older than 55 years. MATERIALS AND METHODS: One hundred eighty shoulders with symptomatic, nontraumatic supraspinatus tears were randomly assigned to 1 of the 3 cumulatively designed treatment groups: physiotherapy (group 1); acromioplasty and physiotherapy (group 2); and rotator cuff repair, acromioplasty, and physiotherapy (group 3). The change in the Constant score was the primary outcome measure. The secondary outcome measures were the change in the visual analog scale score for pain and patient satisfaction. Radiologic analysis included evaluation of glenohumeral osteoarthritis (OA) and rotator cuff tear arthropathy (CTA). RESULTS: A total of 150 shoulders (mean age, 71 years) were available for analysis after a mean follow-up period of 6.2 years. The mean sagittal tear size of the supraspinatus tendon tear at baseline was 10 mm in all groups (P = .33). During follow-up, 8 shoulders in group 1 and 2 shoulders in group 2 crossed over to rotator cuff repair. The mean baseline Constant score was 57.1, 58.2, and 58.7 in groups 1, 2, and 3, respectively (P = .85). There were no significant differences (P = .84) in the mean change in the Constant score: 18.5 in group 1, 17.9 in group 2, and 20.0 in group 3. There were no statistically significant differences in the change in the visual analog scale pain score (P = .74) and patient satisfaction (P = .83). At follow-up, there were no statistically significant differences in the mean progression of glenohumeral OA (P = .538) or CTA (P = .485) among the groups. However, the mean progression of glenohumeral OA from baseline to follow-up was statistically significant in the trial population (P = .0045). CONCLUSIONS: On the basis of this study, operative treatment is no better than conservative treatment regarding small, nontraumatic, single-tendon supraspinatus tears in patients older than 55 years. Operative treatment does not protect against degeneration of the glenohumeral joint or CTA. Conservative treatment is a reasonable option for the primary initial treatment of these tears.

Weekend effect on mortality by medical specialty in six secondary hospitals in the Helsinki metropolitan area over a 14-year period.

BACKGROUND: The weekend effect is the phenomenon of a patient's day of admission affecting their risk for mortality. Our study reviews the situation at six secondary hospitals in the greater Helsinki area over a 14-year period by specialty, in order to examine the effect of centralization of services on the weekend effect. METHODS: Of the 28,591,840 patient visits from the years 2000-2013 in our hospital district, we extracted in-patients treated only in secondary hospitals who died during their hospital stay or within 30 days of discharge. We categorized patients based on the type of each admission, namely elective versus emergency, and according to the specialty of their clinical service provider and main diagnosis. RESULTS: A total of 456,676 in-patients (292,399 emergency in-patients) were included in the study, with 17,231 deaths in-hospital or within 30 days of discharge. A statistically significant weekend effect was observed for in-hospital and 30-day post-discharge mortality among emergency patients for 1 of 7 specialties. For elective patients, a statistically significant weekend effect was visible in in-hospital mortality for 4 of 8 specialties and in 30-day post-discharge mortality for 3 of 8 specialties. Surgery, internal medicine, and gynecology and obstetrics were most susceptible to this phenomenon. CONCLUSIONS: A weekend effect was present for the majority of specialties for elective patients, indicating a need for guidelines for these admissions. More disease-specific research is necessary to find the diagnoses, which suffer most from the weekend effect and adjust staffing accordingly.

Good stability of a cementless, anatomically designed femoral stem in aging women: a 9-year RSA study of 32 patients.

Background and purpose - We previously reported a transient, bone mineral density (BMD)-dependent early migration of anatomically designed hydroxyapatite-coated femoral stems with ceramic-ceramic bearing surfaces (ABG-II) in aging osteoarthritic women undergoing cementless total hip arthroplasty. To evaluate the clinical significance of the finding, we performed a follow-up study for repeated radiostereometric analysis (RSA) 9 years after surgery. Patients and methods - Of the 53 female patients examined at 2 years post-surgery in the original study, 32 were able to undergo repeated RSA of femoral stem migration at a median of 9 years (7.8-9.3) after surgery. Standard hip radiographs were obtained, and the subjects completed the Harris Hip Score and Western Ontario and McMaster Universities Osteoarthritis Index outcome questionnaires. Results - Paired comparisons revealed no statistically significant migration of the femoral stems between 2 and 9 years post-surgery. 1 patient exhibited minor but progressive RSA stem migration. All radiographs exhibited uniform stem osseointegration. No stem was revised for mechanical loosening. The clinical outcome scores were similar between 2 and 9 years post-surgery. Interpretation - Despite the BMD-related early migration observed during the first 3 postoperative months, the anatomically designed femoral stems in aging women are osseointegrated, as evaluated by RSA and radiographs, and exhibit good clinical function at 9 years.

Medium to long-term results of 130 Ankle Evolutive System total ankle replacements-Inferior survival due to peri-implant osteolysis.

BACKGROUND: The study reports the medium to long-term results of 130 Ankle Evolutive System total ankle replacements operated at a single-centre. Previously high amount of peri-implant osteolysis was reported from the same material. METHODS: Between 2002 and 2008 one hundred and thirty consecutive ankles replaced with AES ankle prosthesis were followed both radiologically and clinically. RESULTS: The five-year survival was 87.3% (95% confidence interval (CI) 80.0-92.0%), and ten-year survival 74.9% (95% confidence interval (CI) 65.4-82.2%) at a median follow-up time of 96 months (range 2-161; 8 years). Peri-implant osteolysis was found in 91 (70%) ankles, marked in 78 (60%). 44 ankles (34%) have been revised by filling of the cavities, 24 (18%) by fusion, and 6 by further replacement, resulting in the revision rate of 58%. Osteolysis was the main reason for all revisions. The improvement of the Kofoed Score and pain points was significant (all p<0.0001), and the subjective patient satisfaction was good. CONCLUSIONS: Outcome of the current study was seriously affected by osteolysis and is inferior compared to previous reports.

Are periprosthetic osteolytic lesions in ankle worth bone grafting?

BACKGROUND: We retrospectively evaluated the medium-term follow-up of bone grafting due to periprosthetic osteolytic lesions in ankles. METHODS: 34 ankles (32 patients) with total ankle arthroplasty (TAA) underwent re operation. Indications were large periprosthetic osteolytic lesions or continuous growing of the lesions. The osteolytic lesions were imaged by CT before reoperation and once a year after that. The mean CT follow-up after re operation was 3.8 years (range, 2-6.2 years). Patient's clinical outcome was also monitored. RESULTS: Osteolysis continued to progress in 44 bone grafted lesions (68%) in CT follow-up. Pain (p=0.04) and location of the lesion (p=0.03) were associated with progression of osteolysis. In 18 bone grafted osteolytic lesions (28%) the radiological survival remained excellent. 25 out of 34 ankles showed improvement of the function after bone grafting. CONCLUSIONS: There is no established treatment protocol for osteolysis around TAA. Bone grafting is one alternative in the treatment of osteolytic lesions.

Is Model-based Radiostereometric Analysis Suitable for Clinical Trials of a Cementless Tapered Wedge Femoral Stem?

BACKGROUND: In clinical trials of THA, model-based radiostereometric analysis (RSA) techniques may be less precise than conventional marker-based RSA for measurement of femoral stem rotation. We verified the accuracy and clinical precision of RSA based on computer-aided design models of a cementless tapered wedge femoral stem. QUESTIONS: We asked: (1) Is the accuracy of model-based RSA comparable to that of marker-based RSA? (2) What is the clinical precision of model-based RSA? METHODS: Model-based RSA was performed using combined three-dimensional computer-aided design models of the stem and head provided by the implant manufacturer. The accuracy of model-based RSA was compared with that of marker-based RSA in a phantom model using micromanipulators for controlled translation in three axes (x, y, z) and rotation around the y axis. The clinical precision of model-based RSA was evaluated by double examinations of patients who had arthroplasties (n = 24) in an ongoing trial. The clinical precision was defined as being at an acceptable level if the number of patients needed for a randomized trial would not differ from a trial done with conventional marker-based RSA (15-25 patients per group). RESULTS: The accuracy of model-based RSA was 0.03 mm for subsidence (translation along the y axis) (95% CI for the difference between RSA measurements and actual displacement measured with micrometers, -0.03-0.00) and 0.39° for rotation around the y axis (95% CI, -0.41 to -0.06). The accuracy of marker-based RSA was 0.06 mm for subsidence (95% CI, -0.04-0.01; p = 0.728 compared with model-based RSA) and 0.18° for the y axis rotation (95% CI, -0.23 to -0.07; p = 0.358). The clinical precision of model-based RSA was 0.14 mm for subsidence (95% CI for the difference between double examinations, -0.02-0.04) and 0.79° for the y axis rotation (95% CI, -0.16-0.18). CONCLUSIONS: The accuracy of model-based RSA for measurement of the y axis rotation was not quite as high as that of marker-based RSA, but its clinical precision is at an acceptable level. CLINICAL RELEVANCE: Model-based RSA may be suitable for clinical trials of cementless tapered wedge femoral stem designs.

Adverse reaction to metal debris after Birmingham hip resurfacing arthroplasty.

BACKGROUND AND PURPOSE: Concern has emerged about local soft-tissue reactions after hip resurfacing arthroplasty (HRA). The Birmingham Hip Resurfacing (BHR) was the most commonly used HRA device at our institution. We assessed the prevalence and risk factors for adverse reaction to metal debris (ARMD) with this device. PATIENTS AND METHODS: From 2003 to 2011, BHR was the most commonly used HRA device at our institution, with 249 implantations. We included 32 patients (24 of them men) who were operated with a BHR HRA during the period April 2004 to March 2007 (42 hips; 31 in men). The mean age of the patients was 59 (26-77) years. These patients underwent magnetic resonance imaging (MRI), serum metal ion measurements, the Oxford hip score questionnaire, and physical examination. The prevalence of ARMD was recorded, and risk factors for ARMD were assessed using logistic regression models. The mean follow-up time was 6.7 (2.4-8.8) years. RESULTS: 6 patients had a definite ARMD (involving 9 of the 42 hips). 8 other patients (8 hips) had a probable ARMD. Thus, there was definite or probable ARMD in 17 of the 42 hips. 4 of 42 hips were revised for ARMD. Gender, bilateral metal-on-metal hip replacement and head size were not factors associated with ARMD. INTERPRETATION: We found that HRA with the Birmingham Hip Resurfacing may be more dangerous than previously believed. We advise systematic follow-up of these patients using metal ion levels, MRI/ultrasound, and patient-reported outcome measures.

[Diagnosis of soft tissue tumors--multidisciplinary collaboration]. / Pehmytkudoskasvainten diagnostiikka--moniammatillista yhteistyötä.

The number of soft tissue sarcomas found in Finland yearly is around 200 cases. Benign soft tissue tumors are common. The patients having a tumor with a deep location in the tissue or a large superficial tumor should be readily referred for imaging studies and consultations with the sarcoma teams of university hospitals. The diagnosis of sarcoma is based on medical history, clinical examination, imaging, examination of a biopsy, and frequently also on molecular genetic analyses. In imaging, the best resolution is provided by MRI. Targeting of the biopsy is an essential part of imaging. Gradus is the most important histology-based factor affecting the prognosis and treatment of the tumor.

[Update on current care guidelines. The tendon disorders of the shoulder]. / Kaypa Hoite-Suosituksen Paivitystiivistelma. Olkapään jännevaivat.

Degenerative rotator cuff tendon disease (tendinopathy) is the most common disorder of the shoulder. A full-thickness tear of the rotator cuff may be caused by degeneration, or it may develop due to an acute trauma. The typical symptoms include pain and functional deficiencies. Diagnostics is based on clinical findings. The primary radiologic imaging is x-ray. Degenerative tendon diseases are primarily treated conservatively in primary health care, the most important treatment modality is physiotherapy-guided therapeutic rehabilitation. Surgical treatment is considered in full-thickness rotator cuff tears, especially after traumatic onset.

Imaging Outcomes of Emergency MR Imaging in Dizziness and Vertigo: A Retrospective Cohort Study.

BACKGROUND AND PURPOSE: Patients exhibiting acute dizziness or vertigo often represent a diagnostic challenge, and many undergo neuroimaging for stroke detection. We aimed to demonstrate the imaging outcomes of first-line emergency MR imaging among patients with acute dizziness or vertigo and to determine the clinical risk factors for stroke and other acute pathology. MATERIALS AND METHODS: This retrospective study included consecutive patients with acute dizziness or vertigo referred for emergency MR imaging in a tertiary hospital during 5 years. We recorded and analyzed patient characteristics, relevant clinical information, and imaging outcomes. Risk score models were derived to predict which patients were more likely to present with positive MR imaging findings. RESULTS: A total of 1169 patients were included. Acute stroke was found in 17%; other clinically significant pathology, in 8% of patients. In 75% of the patients, emergency MR imaging showed no significant abnormalities. Risk factors for acute stroke included older age, male sex, and a prevalence of cardiovascular risk factors and neurologic signs. Isolated dizziness had no discriminative power on imaging outcomes, and 14% of these patients showed acute stroke. Risk scores had only moderate performance in predicting acute ischemic stroke (receiver operating characteristic area under curve = 0.75) or any significant pathology (receiver operating characteristic area under curve = 0.70). CONCLUSIONS: Acute dizziness and vertigo remain challenging even when emergency MR imaging is readily available. One in 4 patients had acute pathology on MR imaging. Predictors for acute pathology (older age, male sex, cardiovascular risk factors, and neurologic signs) may aid in patient selection for MR imaging, optimizing the yield and clinical impact of emergency neuroimaging. Low diagnostic yields of CT and internal acoustic canal MR imaging may offer an opportunity to reduce health care expenditures in the future.

Weight-bearing CT imaging of the lower extremity.

OBJECTIVE: The purpose of this article is to describe weight-bearing CT of the lower extremity joints using a novel portable imager utilizing cone-beam CT technology. CONCLUSION: Cone-beam CT technology with new design and flexible gantry movements allows both supine and weight-bearing imaging of the lower extremities, with a reasonable radiation dose and excellent image quality. Weight-bearing CT of joints can provide important new clinical information in musculoskeletal radiology.

Total ankle arthroplasty: optimizing computed tomography imaging protocol.

OBJECTIVE: To evaluate parameters and positioning when imaging total ankle prostheses on computed tomography (CT). MATERIALS AND METHODS: An ankle prosthesis implanted into a pig's knee joint underwent 16 different CT imaging protocols. Four defects were drilled around prosthesis components simulating periprosthetic osteolytic lesions. The specimen with the implant was imaged in four different orientations with the tibial stem parallel to the table and at 25, 45, and 90° angles to it. The protocol consisted of scanning at 100, 120, and 140 kVp in every position with a pitch of 1.2. The scanning at 120 kVp in every position was repeated with a pitch of 1.0. RESULTS: CT proved to be a reliable imaging modality when studying periprosthetic lesions adjacent to the ankle prosthesis when the tibial stem alignment was parallel to the table. When imaging at higher angles, metal artifacts distorted the image, making the analysis of periprosthetic bone structure unreliable. There were no statistically significant differences between different tube voltages or pitch in volume measurements of the osteolytic lesions. CONCLUSIONS: CT is a reliable imaging method to evaluate periprosthetic bone structure around ankle prostheses when orientation of the prosthesis and acquisition parameters is optimized.

CT arthrography of the wrist using a novel, mobile, dedicated extremity cone-beam CT (CBCT).

PURPOSE: To evaluate the feasibility and intra- and interobserver agreement of CBCT arthrography of wrist ligaments, triangular fibrocartilaginous complex (TFCC), and to assess the sensitivity (SE), specificity (SP), accuracy (ACC), and positive and negative predictive value (PPV, NPV) of CBCT arthrography in the diagnosis of scapholunate (SLL) and lunotriquetral (LTL) ligament tears, TFCC, and cartilage abnormalities of the scaphoid and lunate with their corresponding radial surfaces (scaphoid and lunate fossa) using a novel, mobile, dedicated extremity CBCT scanner. MATERIALS AND METHODS: Fifty-two consecutively enrolled subjects (26 M, 26 F, mean age 38 years, range 18-66 years) with suspected wrist ligament tears underwent CBCT-arthrography before normally scheduled MR arthrography.An extremity CBCT was used for imaging with isotropic voxel size of 0.4 × 0.4 × 0.4 mm(3). Subsequent routine 1.5 T MRI was performed using a dedicated wrist coil.Two observers reviewed the anonymized CBCT images twice for contrast enhancement (CE) and technical details (TD), for tears of the SLL, LTL, and TFCC. Also, cartilage abnormalities of the scaphoid and lunate with their corresponding radial surfaces (scaphoid and lunate fossa) were evaluated. Inter- and intraobserver agreement was determined using weighted kappa statistics. Since no surgery was performed, MRI served as a reference standard, and SE and SP, ACC, PPV, and NPV were calculated. RESULTS: Intra- and interobserver kappa values for both readers (reader 1/reader 2; first reading/second reading) with 95 % confidence limits were: CE 0.54 (0.08-1.00)/ 0.75 (0.46-1.00); 0.73 (0.29-1.00)/ 0.45 (0.07-0.83), TD 0.53 (0.30-0.88)/ 0.86 (0.60-1.00); 0.56 (0.22-0.91)/ 0.67 (0.37-0.98), SLL 0.59 (0.25-0.93)/ 0.66 (0.42-0.91); 0.31 (0.06-0.56)/ 0.49 (0.26-0.73), LTL 0.83 (0.66-1.00)/ 0.68 (0.46-0.91); 0.90 (0.79-1.00)/ 0.48 (0.22-0.74); TFCC (0.72-1.00)/ (0.79-1.00); 0.65 (0.43-0.87)/ 0.59 (0.35-0.83), radius (scaphoid fossa) 0.45 (0.12-0.77)/ 0.64 (0.31-0.96); 0.58 (0.19-0.96)/ 0.38 (0.09-0.66), scaphoid 0.43 (0.12-0.74)/ 0.76 (0.55-0.96); 0.37 (0.00-0.75)/ 0.32 (0.04-0.59), radius (lunate fossa) 0.68 (0.36-1.00)/ 0.42 (0.00-0.86); 0.62 (0.29-0.96)/ 0.51 (0.12-0.91), and lunate 0.53 (0.16-0.90)/ 0.68 (0.44-0.91); 0.59 (0.29-0.88)/ 0.42 (0.00-0.84), respectively. The overall mean accuracy was 82-92 % and specificity was 81-94 %. Sensitivity for LTL and TFCC tears was 76-83, but for SLL tears it was 58 %. For cartilage abnormalities, the accuracy and negative predictive value were high, 90-98 %. CONCLUSIONS: A dedicated CBCT extremity scanner is a new method for evaluating the wrist ligaments and radiocarpal cartilage. The method has an overall accuracy of 82-86 % and specificity 81-91 %. For cartilage abnormalities, the accuracy and negative predictive value were high.