Fallstricke in der Magnetresonanztomographie des Kniegelenks

Zusammenfassung: Die Magnetresonanztomographie (MRT) des Kniegelenks ist eine robuste Methode zur Beurteilung von Binnenläsionen. Bei Kenntnis der technischen und anatomischen Fallstricke lassen sich pathologische Veränderungen meistens sicher abgrenzen. Problematisch bleibt die Differenzierung meniskokapsulärer Läsionen von normalen anatomischen Strukturen. Die hohe Prävalenz asymptomatischer Befunde, z.B. Meniskusrisse bis zu 63% auf der asymptomatischen Gegenseite, stellt auf der anderen Seite ein Management-Problem für die behandelnden Ärzte da

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 22.4years. 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 6.1mm in the proximal aspect and 2.5mm in the distal aspect of the trochlea, while the patella medialised a mean of 5mm. 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 5.9mm postoperatively in the proximal aspect of the trochlea, and from 5.5 to 8.3mm 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 patell

MR/CT image fusion of the spine after spondylodesis: a feasibility study

The objective of this study is to evaluate feasibility, accuracy and time requirements of MR/CT image fusion of the lumbar spine after spondylodesis. Sagittal MR and CT images derived from standard imaging protocols (sagittal T2-weighted MR/sagittal reformatted multi-planar-reformation of the CT) of the lumbar spine with correct (n=5) and incorrect (n=5) implant position were fused by two readers (R1, R2) using OsiriX in two sessions placing one (session 1) or two (session 2) reference point(s) on the dorsal tip(s) of the cranial and caudal endplates from the second lumbar to the first sacral vertebra. R1 was an experienced musculoskeletal radiologist; R2 a spine surgeon, both had received a short training on the software tool. Fusion times and fusion accuracy, defined as the largest deviation between MR and CT in the median sagittal plane on the ventral tip of the cranial end plate of the most cranial vertebra visible on the CT, were measured in both sessions. Correct or incorrect implant position was evaluated upon the fused images for all patients by an experienced senior staff musculoskeletal radiologist. Mean fusion time (session 1/session 2; in seconds) was 100.4/95 (R1) and 104.2/119.8 (R2). Mean fusion deviation (session 1/session 2; in mm) was 1.24/2.20 (R1) and 0.79/1.62 (R2). The correct/incorrect implant position was identified correctly in all cases. In conclusion, MR/CT image fusion of the spine with metallic implants is feasible, fast, accurate and easy to implement in daily routine wor

The Charcot foot: a pictorial review.

Charcot foot refers to an inflammatory pedal disease based on polyneuropathy; the detailed pathomechanism of the disease is still unclear. Since the most common cause of polyneuropathy in industrialized countries is diabetes mellitus, the prevalence in this risk group is very high, up to 35%. Patients with Charcot foot typically present in their fifties or sixties and most of them have had diabetes mellitus for at least 10 years. If left untreated, the disease leads to massive foot deformation. This review discusses the typical course of Charcot foot disease including radiographic and MR imaging findings for diagnosis, treatment, and detection of complications

CT-guided cervical nerve root injections: comparing the immediate post-injection anesthetic-related effects of the transforaminal injection with a new indirect technique

Objective To describe an “indirect” cervical nerve root injection technique with a dorsal approach that should carry less inherent risk than the “direct” cervical transforaminal injection approach, and to compare the immediate postinjection results of the two procedures. Materials and methods The indirect and direct cervical nerve root injection procedures are described in detail. Fifty-three consecutive patients receiving the indirect nerve root injections during 2009–2010 were age- and gendermatched to 53 patients who underwent direct transforaminal nerve root injections performed in 2006. Pain level data were collected immediately before and 20–30 min after each procedure. The percentages of pain change in the two groups were compared using the unpaired Student’s t test. Results Fifty-two men (mean age 49) and 54 women (mean age 55) were included. The mean percentage of pain reduction for patients receiving indirect nerve root injections was 38.4% and for those undergoing the direct nerve root injections approach it was 43.2%. This was not significantly different (P=0.455). No immediate or late adverse effects were reported after either injection procedure. Conclusions The indirect cervical nerve root injection procedure is a potentially safer alternative to direct cervical transforaminal nerve root injections. The short-term pain reduction is similar using the two injection methods

Does the Constitution Provide More Ballot Access Protection for Presidential Elections Than for U.S. House Elections?

Both the U.S. Constitution and The Federalist Papers suggest that voters ought to have more freedom to vote for the candidate of their choice for the U.S. House of Representatives than they do for the President or the U.S. Senate. Yet, strangely, for the last thirty-three years, the U.S. Supreme Court and lower courts have ruled that the Constitution gives voters more freedom to vote for the candidate of their choice in presidential elections than in congressional elections. Also, state legislatures, which have been writing ballot access laws since 1888, have passed laws that make it easier for minor-party and independent candidates to get on the ballot for President than for the U.S. House. As a result, voters in virtually every state invariably have far more choices on their general election ballots for the President than they do for the House. This Article argues that the right of a voter to vote for someone other than a Democrat or a Republican for the House is just as important as a voter’s right to do so for President, and that courts should grant more ballot access protection to minor-party and independent candidates for the House

Interplay of magnetization dynamics with a microwave waveguide at cryogenic temperatures

In this work, magnetization dynamics is studied at low temperatures in a hybrid system that consists of a thin epitaxial magnetic film coupled with a superconducting planar microwave waveguide. The resonance spectrum was observed over a wide magnetic field range, including low fields below the saturation magnetization and both polarities. Analysis of the spectrum via a fitting routine we develop allows the derivation of all magnetic parameters of the film at cryogenic temperatures, the detection of waveguide-induced uniaxial magnetic anisotropies of the first and the second order, and the uncovering of a minor misalignment of the magnetic field. A substantial influence of the superconducting critical state on the resonance spectrum is observed and discussed

Accuracy of magnetic resonance studies in the detection of chondral and labral lesions in femoroacetabular impingement : systematic review and meta-analysis

Background: Several types of Magnetic resonance imaging (MRI) are commonly used in imaging of femoroacetabular impingement (FAI), however till now there are no clear protocols and recommendations for each type. The aim of this meta-analysis is to detect the accuracy of conventional magnetic resonance imaging (cMRI), direct magnetic resonance arthrography (dMRA) and indirect magnetic resonance arthrography (iMRA) in the diagnosis of chondral and labral lesions in femoroacetabular impingement (FAI). Methods: A literature search was finalized on the 17th of May 2016 to collect all studies identifying the accuracy of cMRI, dMRA and iMRA in diagnosing chondral and labral lesions associated with FAI using surgical results (arthroscopic or open) as a reference test. Pooled sensitivity and specificity with 95% confidence intervals using a random-effects meta-analysis for MRI, dMRA and iMRA were calculated also area under receiver operating characteristic (ROC) curve (AUC) was retrieved whenever possible where AUC is equivocal to diagnostic accuracy. Results: The search yielded 192 publications which were reviewed according inclusion and exclusion criteria then 21 studies fulfilled the eligibility criteria for the qualitative analysis with a total number of 828 cases, lastly 12 studies were included in the quantitative meta-analysis. Meta-analysis showed that as regard labral lesions the pooled sensitivity, specificity and AUC for cMRI were 0.864, 0.833 and 0.88 and for dMRA were 0.91, 0.58 and 0.92. While in chondral lesions the pooled sensitivity, specificity and AUC for cMRI were 0.76, 0.72 and 0.75 and for dMRA were 0.75, 0.79 and 0.83, while for iMRA were sensitivity of 0.722 and specificity of 0.917. Conclusions: The present meta-analysis showed that the diagnostic test accuracy was superior for dMRA when compared with cMRI for detection of labral and chondral lesions. The diagnostic test accuracy was superior for labral lesions when compared with chondral lesions in both cMRI and dMRA. Promising results are obtained concerning iMRA but further studies still needed to fully assess its diagnostic accuracy