Normal age-related patterns of cellular and fatty bone marrow distribution in the axial skeleton: MR imaging study

The signal intensity of the normal odontoid process (dens) displayed on magnetic resonance images

In order to analyse the normal signal intensity of the medullary space of the odontoid process (dens) relative to age, the craniovertebral junction of 33 asymptomatic volunteers in six age groups was examined by means of magnetic resonance imaging. To avoid partial-volume effects 3-mm slices were used in sagittal and axial planes. The signal intensities relative to cerebral white matter varied from 0.51 to 1.23 in the sagittal plane and 0.56 to 1.51 in the axial plane. The signal intensities relative to muscle varied from 0.76 to 2.40 in the sagittal plane and 0.96 to 2.30 in the axial plane. The signal intensities relative to fat varied from 0.22 to 0.62 in the sagittal plane and 0.23 to 0.68 in the axial plane. No correlation with age of the volunteers was found. The normal medulla of the dens may exhibit a low signal intensity on T1-weighted images irrespective of age.

Adipogenesis in a myeloid supporting bone marrow stromal cell line

The bone marrow stroma contains pre-adipocyte cells which are part of the hemopoietic microenvironment. Cloned stromal cell lines differ both in their ability to support myeloid and lymphoid development and in their ability to undergo adipocyte differentiation in vitro. These processes have been examined in the +/+2.4 murine stromal cell line and compared to other stromal and pre-adipocyte cell lines. In long-term cultures, the +/+2.4 stromal cells support myeloid cell growth, consistent with their expression of macrophage-colony stimulating factor mRNA. However, despite the presence of mRNA for the lymphoid supportive cytokines interleukins 6 and 7, +/+2.4 cells failed to support stromal cell dependent B lineage lymphoid cells in vitro, suggesting that these stromal cells exhibit only a myelopoietic support function. The +/+2.4 cells differentiate into adipocytes spontaneously when cultured in 10% fetal bovine serum. The process of adipogenesis can be accelerated by a number of agonists based on morphologic and gene marker criteria. Following induction with hydrocortisone, methylisobutylxanthine, indomethacin, and insulin in combination, a time dependent increase in the steady state mRNA and enzyme activity levels of the following adipocyte specific genes was observed: adipocyte P2, adipsin, CAAT/enhancer binding protein, and lipoprotein lipase. In contrast, adipogenesis was accompanied by a slight decrease in the signal intensity of the macrophage-colony stimulating factor mRNA level, similar to that which has been reported in other bone marrow stromal cell lines. These data demonstrate that although the lympho-hematopoietic support function of pre-adipocyte bone marrow stromal cell lines is heterogeneous, they share a common mechanism of adipogenesis.

Value of MRI and MIBG-I123 scintigraphy in the diagnosis of spinal bone marrow involvement in neuroblastoma in children

The results of MRI and MIBG scintigraphy performed on the spine of 14 children with neuroblastoma are reported. In 6 cases of diffuse spinal bone marrow tumor infiltration, diagnosis is easier with MIBG scintigraphy than with MRI. In 5 cases, MRI detected hyposignal of the vertebral body without any spinal abnormality on MIBG scintigraphy. A discussion of the reasons for negative MIBG scintigraphy is presented and in these 5 cases, it is suggested that a lateral view of MIBG scintigraphy and HMDP-Tc99m scintigraphy may be performed, even vertebral body biopsy in order to assess bone marrow tumoral infiltration.

Normal childhood developmental patterns in skull bone marrow by MR imaging

To establish the normal developmental pattern of skull bone marrow in children by MR imaging, sagittal T1-weighted MR skull images of 324 normal children (newborn to 18 years) were reviewed. Bone marrow intensity was assigned four gradations as compared with that of muscle and fat on the same image. Bone marrow became isointense with fat (yellow marrow) at a mean age +/- S.E.M. (in years) of 8.5 +/- 0.24 in sphenoid, 9.1 +/- 0.29 in mandible, 9.3 +/- 0.28 in hard palate, 9.7 +/- 0.26 in frontal, 11.0 +/- 0.26 in squamous occiput, 11.5 +/- 0.28 in parietal, and 11.9 +/- 0.24 in basiocciput. There is a strong correlation between age and marrow intensity by Spearman analysis (p < 0.001): hard palate 0.64, mandible 0.61, parietal 0.42, sphenoid 0.70, cervical spine 0.50, basi-occiput 0.58 and occiput 0.52. Two consistent overall patterns of red-yellow marrow conversion were observed. Bone marrow became isointense with fat prior to pneumatization of the paranasal sinuses. Marrow conversion in the bones of the face occurred before those of the calvarium in a specific pattern. There was no significant sex difference in the pattern or rate of marrow conversion. These normative data are necessary to evaluate the immature skull by MR imaging in disease states.

Medical imaging

There is now a wide choice of medical imaging to show both focal and diffuse pathologies in various organs. Conventional radiology with plain films, fluoroscopy and contrast medium have many advantages, being readily available with low-cost apparatus and a familiarity that almost leads to contempt. The use of plain films in chest disease and in trauma does not need emphasizing, yet there are still too many occasions when the answer obtainable from a plain radiograph has not been available. The film may have been mislaid, or the examination was not requested, or the radiograph had been misinterpreted. The converse is also quite common. Examinations are performed that add nothing to patient management, such as skull films when CT will in any case be requested or views of the internal auditory meatus and heal pad thickness in acromegaly, to quote some examples. Other issues are more complicated. Should the patient who clinically has gall-bladder disease have more than a plain film that shows gall-stones? If the answer is yes, then why request a plain film if sonography will in any case be required to 'exclude' other pathologies especially of the liver or pancreas? But then should cholecystography, CT or scintigraphy be added for confirmation? Quite clearly there will be individual circumstances to indicate further imaging after sonography but in the vast majority of patients little or no extra information will be added. Statistics on accuracy and specificity will, in the case of gall-bladder pathology, vary widely if adenomyomatosis is considered by some to be a cause of symptoms or if sonographic examinations 'after fatty meals' are performed. The arguments for or against routine contrast urography rather than sonography are similar but the possibility of contrast reactions and the need to limit ionizing radiation must be borne in mind. These diagnostic strategies are also being influenced by their cost and availability; purely pragmatic considerations are not infrequently the overriding factor. Non-invasive methods will be preferred, particularly sonography as it is far more acceptable by not being claustrophobic and totally free of any known untoward effects. There is another quite different but unrelated aspect. The imaging methods, apart from limited exceptions, cannot characterize tissues as benign or malignant, granulomatous or neoplastic; cytology or histology usually provides the answer. Sonography is most commonly used to locate the needle tip correctly for percutaneous sampling of tissues. Frequently sonography with fine needle aspiration cytology or biopsy is the least expensive, safest and most direct route to a definitive diagnosis. Abscesses can be similarly diagnosed but with needles or catheters through which the pus can be drained. The versatility and mobility of sonography has spawned other uses, particularly for the very ill and immobile, for the intensive therapy units and for the operating theatre, as well in endosonography. The appointment of more skilled sonographers to the National Health Service could make a substantial contribution to cost-effective management of hospital services. Just when contrast agents and angiography have become safe and are performed rapidly, they are being supplanted by scanning methods. They are now mainly used for interventional procedures or of pre-operative 'road maps' and may be required even less in the future as MRI angiography and Doppler techniques progress. MRI will almost certainly extent its role beyond the central nervous system (CNS) should the equipment become more freely available, especially to orthopaedics. Until then plain films, sonography or CT will have to suffice. Even in the CNS there are conditions where CT is more diagnostic, as in showing calculations in cerebral cysticercosis. Then, too, in most cases CT produces results comparable to MRI apart from areas close to bone, structures at the base of the brain, in the posterior fossa and in the spinal cord. Scintigraphy for pulmonary infarcts and bone metastases and in renal disease in children plays a prominent role and its scope has increased with new equipment and radionuclides. Radio-immunoscintigraphy in particular is likely to expand greatly not only in tumour diagnosis but also in metabolic and infective conditions. Whether the therapeutic implications will be realized is more problematic. The value of MRS and NM for metabolic studies in clinical practice is equally problematical, although the data from cerebral activity are extremely interesting. While scanning has replaced many radiographic examinations, endoscopy has had a similar effect on barium meals and to a lesser extent on barium enemas. The combined visual/sonographic endoscope is likely to accelerate this process. There is no doubt that over the last 2 decades medical imaging has changed the diagnostic process, but its influence on the outcome of disease other than infections is less certain and probably indefinable. Data concerning the comparative efficacy in terms of patient outcome for each of the imaging techniques would be of considerable interest and a great help in determining diagnostic strategies.