Is there functional vascular information in anatomical MR sequences? A preliminary in vivo study.

According to the type of sequences used, either morphological or dynamic functional study can be performed using magnetic resonance imaging (MRI). The aim of this study is to find out if vascular information found, in dynamic MR sequences, already exists in anatomical MR sequences in the particular case of Legg-Calvé-Perthes disease (LCPD). LCPD is due to a loss of circulation to the femoral head in a growing child resulting in avascular necrosis and leading to possible distortion of size and shape of the proximal femur. MRI acquisitions consist in performing two anatomical sequences and one dynamic sequence with a gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) injection. Five new parametric images characterizing hyper- and hypo-vascularized areas are computed from the dynamic MR sequence. For each new image, the two corresponding anatomical images are found and registered. Then, four types of regions of interest (ROIs) are extracted: healthy hyper- and hypo-vascularized areas and pathological hyper- and hypo-vascularized areas. First-order statistical parameters and texture parameters (Haralick's method, run length method, fractal parameters, autoregressive factors and Laws' texture energy method) are computed in each ROI. Then, a statistical study based on a T test is performed. Results show that some parameters could discriminate the four ROI types. Hence, dynamic vascular image and intrinsic anatomical image characteristics seem to be correlated. Finally, the disease can be evaluated with objective parameters using only anatomical sequences.