A. Chevrot

Longitudinal stress fractures of the tibia: comparative study of CT and MR imaging.

Abstract. The aim of this study was to compare the performance of CT and MRI in the diagnosis of longitudinal stress fracture of the tibia (LSFT). A retrospective study of imaging findings was performed in 15 patients with LSFT. The CT and MR images were compared for detection of fracture line, callus, bone marrow edema, and soft tissues changes. The CT and MRI techniques allowed the detection of the fracture line in 82 and 73 % of cases, respectively. The callus was always visualized with CT or MRI. The MRI technique had a markedly higher sensitivity than CT in the detection of bone marrow edema (73 vs 18 %) and soft tissue lesions (87 vs 9 %). This may cause a misleading aggressive appearance on MRI. Computed tomography remains the best imaging modality for diagnosis of LSFT. However, MRI findings should be known to obviate the performance of CT or bone biopsy.

Les clichés simples du bassin

Plain films of pelvis Plain films of the pelvis remain informative and allow most of the diagnoses. Assesment of the hip joint space, bone and subchondral structures, sacrum as well as sacroiliac joints is made on the AP view. Oblique views are useful. Five different oblique views are described: Lequesne’s view, Ducroquet’s view, Arcelin’s view, medical and urethral views. They particularly allow assement of the acetabulum, the femoral head and neck as well as the femoral superior third. Radiological technique and major indications for these views must be known. Angle measurement and evaluation of possible dysplasia are made on coxometry views.

Assessment of vascular invasion by bone and soft tissue tumours of the limbs: usefulness of MDCT angiography

ObjectiveTo evaluate the accuracy of computed tomography angiography (CTA) in predicting arterial encasement by limb tumours, by comparing CTA with surgical findings (gold standard).MethodsPreoperative CTA images of 55 arteries in 48 patients were assessed for arterial status: cross-sectional CTA images were scored as showing a fat plane between artery and tumour (score 0), slight contact between artery and tumour (score 1), partial arterial encasement (score 2) or total arterial encasement (score 3). Reformatted CTA images were assessed for arterial displacement, rigid wall, stenosis or occlusion. At surgery, arteries were classified as free or surgically encased; 45 arteries were free and 10 were surgically encased.ResultsMultivariate logistic regression identified the axial CTA score as a relevant predictor for arterial encasement and subsequent vascular intervention during surgery. All sites where CTA showed a fat plane between the tumour and the artery were classified as free at surgery (n = 28/28). The sensitivity of total arterial encasement on CTA (score 3) was 90%, specificity 93%, accuracy 93% and positive likelihood ratio 13.5.ConclusionCTA evidence of total arterial encasement is a highly specific indication of arterial encasement. The presence of fat between the tumour and the artery on CTA rules out arterial involvement at surgery.

Ruptures hyperéchogènes de la coiffe des rotateurs

Resume Objectifs Decrire des cas inhabituels de rupture de la coiffe des rotateurs qui ont la particularite d’etre hyperechogenes en echographie. Materiel et methodes Les auteurs ont revu retrospectivement l’aspect echographique de 100 ruptures de la coiffe des rotateurs affirmees par arthroscanner comprenant une injection de produit de contraste dans l’articulation gleno-humerale et, en l’absence de rupture transfixiante, dans la bourse sous acromio-deltoidienne. Nous avons retenus les foyers hyperechogenes sans halo hypo-echogene peripherique. Une 2e echographie a ete realisee apres arthroscanner et distension de la bourse sous acromio-deltoidienne. Resultats Le taux de foyers hyperechogenes est de 6 % des ruptures de la coiffe. Cinq des 6 furent initialement consideres comme tendinite ou variante de la normale et un comme rupture transfixiante. En fait il s’agissait de 4 ruptures partielles superficielles et 2 ruptures transfixiantes au scanner. L’echographie realisee apres injection montrait dans tous les cas un remplacement total ou partiel du foyer hyperechogene par une zone liquidienne probablement due au remplissage de la lesion par des fragments de fibrine ou de BSAD epaissie. Conclusion Des ruptures hyperechogenes peuvent expliquer certains des faux negatifs de l’echographie dans la detection des ruptures de la coiffe des rotateurs.

Comment je fais un bilan échographique des mains et des pieds dans la polyarthrite rhumatoïde

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by progressive damage of synovial-lined joints and variable extra-articular manifestations. Synovitis is usually found in the wrist, metacarpophalangeal, proximal interphalangeal and metatarsophalangeal joints. For these reasons, we believe that ultrasound with power doppler can be used for the detection and monitoring of synovitis with a simplified “hands and feet” protocol. In this article, we will describe this protocol used daily in our institution for early diagnosis and therapeutic management of this disease.

Échographie des tendons de la coiffe en mode harmonique : les clivages sont-ils enfin visibles ?

Harmonic sonography of rotator cuff tendons: are cleavage tears visible at last? Purpose. For some, cleavage tears remain a pitfall of sonography (US). The purpose of this study is to demonstrate the visibility of intratendinous tears of the supraspinatus and infraspinatus tendons and describe their imaging features on tissue harmonic US. Materials and methods. Prospective study of 52 patients with suspected cuff pathology who underwent US prior to CT-arthrography, CT-bursography or MR arthrography. The US examinations were performed using 7-15MHz transducers with tissue harmonic mode (pulse subtraction). An intratendinous tear was suggested by the presence of a hypoechoic intratendinous line, extending from a partial or full thickness tear. Results from US were correlated to contrast material enhanced CT or MR findings. Results. Ten cases of cleavage tears were detected on US compared to 18 on arthrographic examinations. False negative results occurred in poor US candidates (n=4), excessively retracted tendons (n=2) or postsurgical cuffs (n=2). Sensitivity was 55% and specificity was 94%, with PPV of 83% and NPV of 80% for the detection of intratendinous tear. The accuracy of US was lower for intratendinous tear associated with full thickness tears (5/11) compared to intratendinous tears associated with partial thickness tears (5/6). Conclusion. We demonstrate that cleavage tears are now visible on US using high-frequency transducers and tissue harmonic mode. However, the sensitivity remains too low, especially in patients with full thickness tear, postsurgical patients and patients that are poor candidates to US.

Faux anévrisme de l'artère fémorale compliquant une maladie des exostoses multiples.

exostose osteogenique ou osteochondrome est la tumeur osseuse la plus frequente de l’organisme (10 a 15 % de l’ensemble des tumeurs osseuses (1)). L’exostose est en general unique, sauf dans le cadre de la maladie des exostoses multiples, affection hereditaire autosomique dominante. Les exostoses se developpent a la surface de l’os par un processus d’ossification enchondrale qui prend fin a l’arret de la croissance. Leur base osseuse, sessile ou pediculee, est recouverte chez l’enfant d’une coiffe cartilagineuse lisse et homogene qui s’amincit avec l’âge et disparait par endroits. A l’âge adulte, ces osteochondromes sont en general stables en taille et asymptomatiques. Parfois la coiffe cartilagineuse peut s’hypertrophier et degenerer en chondrosarcome. Les autres complications de l’exostose peuvent etre un conflit musculo-tendineux avec formation de bursite, une compression nerveuse, une fracture d’exostose, ou une lesion vasculaire. Nous rapportons ici un cas de formation d’un faux anevrisme arteriel au contact d’un osteochondrome avec des images d’angioIRM et d’angioscanner non encore rapportees dans la litterature.

Chondrosarcomes dédifférenciés : revue iconographique radio-pathologique

Dedifferentiated chondrosarcoma : radiologic-pathologic correlation Dedifferentiated chondrosarcomas are highly malignant tumors characterized by conventional low-grade chondrosarcoma with abrupt transition to foci that have dedifferentiated into a higher-grade noncartilaginous more aggressive sarcoma. The dedifferentiated component, an osteosarcoma or fibrosarcoma, determines the prognosis. Its identification is key for management. A diagnosis of dedifferentiated chondrosarcoma should be suggested by the presence of “tumoral dimorphism” with cartilaginous component and aggressive lytic component invading adjacent soft tissues.

IRM et spondylarthropathie

Objectifs Connaitre le protocole IRM pour explorer une SPA. Connaitre la semiologie IRM d’une SPA. Savoir distinguer une IRM avec signes d’activite d’une IRM avec signes de maladie chronique. Messages a retenir L’apport de l’IRM est certain pour le diagnostic precoce, meme si cet examen peut etre negatif dans une vraie spondylarthrite. Les cohortes actuellement en cours de constitution, telle la cohorte nationale DESIR (DEvenir des Spondylarthropathies Indifferenciees Recentes), devraient, a terme, offrir un outil de travail susceptible d’evaluer de nouveaux algorithmes de diagnostic precoce, et de mieux preciser la place de l’imagerie en pratique courante. Resume Une IRM des sacro-iliaques doit etre realisee en sequence STIR (suppression de graisse) et en sequence Tl. L’injection intraveineuse de gadolinium n’est pas utile en pratique courante dans cette indication. L’IRM du rachis entier apporte des informations supplementaires et peut donc etre conseillee : il n’existe cependant pas de consensus a ce sujet, pour notre part nous conseillons cet examen. Il est important de preciser qu’il s’agit d’une recherche d’inflammation, afin que les sequences adaptees (STIR) soient realisees.

Imagerie des tendinopathies du poignet

Objectifs pedagogiques Connaitre les principales tendinopathies du poignet et leurs mecanismes. Discuter les anomalies osseuses associees visibles sur les radiographies. Connaitre l’apport respectif de l’echographie et de l’IRM. Discuter l’importance d’une imagerie dynamique des tendons. Connaitre les elements cles du compte rendu d’une tendinopathie du poignet. Messages a retenir Les tendinopathies du poignet sont dues le plus souvent a une hypersollicitation chronique. Des traumatismes aigus sont possibles avec rupture tendineuse ou de certains retinaculum. L’echographie et l’IRM doivent preciser les degâts intratendineux et les complications (rupture, instabilite). L’imagerie doit rechercher les etiologies responsables du caractere rebelle d’une tendinopathie.