Red bone marrow.

Look here to this image, revealed a normal intensity of the yellow bone marrow seen in adult if compared to the intensity of the muscle.

While here, we see that the lesion in the head of the femur is hypo intense  in this T2 image suggesting presence of red bone marrow.

So in case of red bone marrow, the patient will have a hypo intense lesion in T1 and T2, while in case of yellow bone marrow, it appears as a hyper intense in T1, intermediate signal in T2.