Diffusion MRI in ischemic epiphysis of the femoral head: An experimental study

Abstract

Purpose: To evaluate whether line-scan diffusion-weighted imaging (LSDWI) can provide temporal information of epiphyseal ischemia. Materials and Methods:Ischemia was induced by ligation of arteries of the unilateral femoral head in piglets (N ϭ 25). LSDWI was performed at several time points after ligation. A comparison of apparent diffusion coefficients (ADCs) was made between ischemic and control sides. The difference in percentage change of ADC in the ischemic hips between two neighboring time points was evaluated. A histological study was made after MR scanning.Results: Three hours after ligation, ADCs were significantly lower in the ischemic hips than in the contralateral (control) hips. At 72 hours after surgery, ADCs in the ischemic hips were significantly higher than in the control hips and continued to rise up until the sixth week after operation. Histological study revealed necrosis of chondrocytes and osteocytes and abnormal thickening of the epiphyseal cartilage in the ischemic femoral head. Conclusion:The ADCs may be used as a marker of ischemia and necrosis in the femoral head; changes in the ADCs after the acute ischemia may reflect the evolution of ischemia and subsequent necrosis. LSDWI can be used for the evaluation of the duration and extent of ischemic injury in the epiphysis.

Magnetic resonance imaging in children with sickle cell disease—detecting alterations in the apparent diffusion coefficient in hips with avascular necrosis

“…Hip ischemia in a piglet model of avascular necrosis (AVN) demonstrates initial restriction in diffusion with reduced blood flow. With increasing duration of ischemia, the diffusion increases rapidly and remains elevated [3][4][5] and in Legg-Calvé-Perthes disease, preliminary data indicate that epiphyseal diffusion varies with the stage of disease [5,6].…”

IRM de diffusion du col fémoral dans la maladie de Legg-Perthes-Clavé : étude préliminaire

“…En imagerie osseuse pédiatrique, elle est étu-diée dans la caractérisation tumorale, l'évaluation de la réponse thérapeutique antitumorale, les infections, l'étude du cartilage et l'ostéonécrose [24][25][26][27]. Si plusieurs travaux expérimentaux [17][18][19] ont étudié les conséquences de l'ischémie sur la diffusion osseuse, peu d'études ont analysé les résultats de la diffusion dans la MLPC tout en la comparant aux autres séquences IRM [22,23]. Ces deux études concernent un plus petit nombre de patients : 12 patients pour Merlini et al [22] et 17 pour Yoo et al [23].…”

“…L'augmentation de l'ADC du col fémoral apparaît dès le premier mois dans notre série, ce qui est en accord avec les résultats obtenus chez l'animal [17][18][19]. La DWI pourrait ainsi être utile dès le début de MLPC.…”

“…Des expérimentations animales ont montré l'intérêt de l'imagerie de diffusion en IRM (DWI) de la tête fémorale dans le diagnostic précoce d'ischémie [17][18][19]. Chez l'homme, une augmentation persistante du coefficient apparent de diffusion (ADC) dans la tête fémorale a été décrite en cas de nécrose ischémique [20][21][22][23].…”

Legg-Calvé-Perthes hastalığında MR görüntüleme

“…[10] DAG'nin, femur başı epifizi iskemisinin erken tespitinde oldukça duyarlı bir yöntem olduğu, birçok hayvan çalışması ile ortaya konulmuştur. [11] İskemik olayın hemen sonrasında diffüzyon kısıtlaması görülse de, saatler ya da günler içe-risinde hem diffüzyon hem de ADC değerlerinde artış görüldüğü ifade edilmiştir. Baunin ve arkadaşları [12] yaptıkları çalışmada, erken dönemde DAG ile görüntülenen LCP olgularında, femur başı epifizi ve metafizinde ADC değerlerinde kontrol grubuna göre artış olduğunu saptamışlardır.…”