<P> To diagnose diseases involving the bone marrow, a bone marrow aspiration is sometimes performed . This typically involves using a hollow needle to acquire a sample of red bone marrow from the crest of the ilium under general or local anesthesia . </P> <P> On CT and plain film, marrow change can be seen indirectly by assessing change to the adjacent ossified bone . Assessment with MRI is usually more sensitive and specific for pathology, particularly for hematologic malignancies like leukemia and lymphoma . These are difficult to distinguish from the red marrow hyperplasia of hematopoiesis, as can occur with tobacco smoking, chronically anemic disease states like sickle cell anemia or beta thalassemia, medications such as granulocyte colony - stimulating factors, or during recovery from chronic nutritional anemias or therapeutic bone marrow suppression . On MRI, the marrow signal is not supposed to be brighter than the adjacent intervertebral disc on T1 weighted images, either in the coronal or sagittal plane, where they can be assessed immediately adjacent to one another . Fatty marrow change, the inverse of red marrow hyperplasia, can occur with normal aging, though it can also be seen with certain treatments such as radiation therapy . Diffuse marrow T1 hypointensity without contrast enhancement or cortical discontinuity suggests red marrow conversion or myelofibrosis . Falsely normal marrow on T1 can be seen with diffuse multiple myeloma or leukemic infiltration when the water to fat ratio is not sufficiently altered, as may be seen with lower grade tumors or earlier in the disease process . </P> <P> Bone marrow examination is the pathologic analysis of samples of bone marrow obtained via biopsy and bone marrow aspiration . Bone marrow examination is used in the diagnosis of a number of conditions, including leukemia, multiple myeloma, anemia, and pancytopenia . The bone marrow produces the cellular elements of the blood, including platelets, red blood cells and white blood cells . While much information can be gleaned by testing the blood itself (drawn from a vein by phlebotomy), it is sometimes necessary to examine the source of the blood cells in the bone marrow to obtain more information on hematopoiesis; this is the role of bone marrow aspiration and biopsy . </P> <P> The ratio between myeloid series and erythroid cells is relevant to bone marrow function, and also to diseases of the bone marrow and peripheral blood, such as leukemia and anemia . The normal myeloid - to - erythroid ratio is around 3: 1; this ratio may increase in myelogenous leukemias, decrease in polycythemias, and reverse in cases of thalassemia . </P>

Where is bone marrow found in long bones