Early Ischemia in Growing Piglet Skeleton: MR Diffusion and Perfusion Imaging

Abstract

Diffusion is sensitive to early ischemia and follows a different time course than that of changes observed with gadolinium enhancement. ADC remained elevated in this model of severe, prolonged ischemia despite the spontaneous partial restoration of blood flow seen on gadolinium-enhanced images.

Femoral Head Deformation and Repair Following Induction of Ischemic Necrosis

“…The longer-term study described in the present report added sectioning of the ligamentum teres to induce femoral head ischemia and necrosis, a technique used successfully in other studies 1,2,4 . The blood supply of the proximal part of the femur in the piglet appears to be the same as in the human 11 .…”

“…For all imaging sequences, low signal intensity (black image) is similar to dense cortical bone, intermediate signal intensity is similar to the image of muscle (non-fat-suppressed), and high signal intensity (light image) is similar to fluid (on a fluid-sensitive sequence such as T2). Gadolinium enhancement with T1-weighted imaging is particularly valuable in demonstrating normal vascularity (high signal intensity) 6 and ischemia of the proximal femoral epiphyses (low signal intensity) 3,4,7 . With the application of different sequences, specific tissues can be highlighted, although not all tissue groups are demonstrated well on each sequence.…”

“…In this study, we report the use of the femoral neck ligation-ligamentum teres sectioning model in three-week-old piglets with assessments by qualitative and quantitative sequential magnetic resonance imaging and end-stage histologic assessment in each to demonstrate the deformation and repair responses of the femoral heads to the vascular injury with time. This investigation of the piglet femoral head differs from previous studies, providing meaningful observations by (1) using magnetic resonance imaging to follow the development of deformity in vivo, assessing the same hips through various time stages; (2) quantifying the changing parameters of deformity by magnetic resonance imaging to help to clarify the mechanism of deformation; (3) using gadolinium-enhanced magnetic resonance imaging to assess the vascular status in necrosis and repair; (4) showing the variability of tissue responses by histologic analysis; and (5) correlating magnetic resonance imaging and histologic tissue differentiation patterns.…”

“…ntracapsular surgical ligation at the base of the femoral neck and sectioning of the ligamentum teres is an excellent model for inducing ischemia and necrosis in the immature piglet femoral head [1][2][3][4] . While the development of femoral head deformity is a well-recognized finding with necrosis, the contributions of collapse, slowed growth, and asymmetric growth to deformation remain uncertain.…”

Is the femoral head dead or alive before surgery of slipped capital femoral epiphysis? Interest of perfusion Magnetic Resonance Imaging

“…Gadolinium-enhanced MR imaging is a non-ionizing radiation technique that has been used to demonstrate lack of adequate blood flow in ischemic bone with a perfect histologic correlation. 10,11 MRI with dynamic gadolinium enhanced subtraction sequences appeared to be a reliable technique for the evaluation of the femoral head vascularization in Legg Calve Perthes disease and in SCFE. This technique has a good sensitivity, high space and contrast resolution to detect femoral head morphologic abnormalities and assess ischemia severity.…”