Variations in the amount of calcified tissue at the attachments of the quadriceps tendon and patellar ligament in man

Differences are reported in the total calcified tissue/bone marrow ratios and in the total thickness of cortical calcified tissue (lamellar bone and calcified fibrocartilage) between the attachment sites of the quadriceps tendon and the patellar ligament in man. The greatest amount of calcified tissue is at the insertion of the tendon and this is correlated with the larger force that the tendon transmits. It is concluded that differences in maximum force alone can produce a greater density of calcified tissue at ligament or tendon attachments. The similar amounts of calcified tissue at each end of the patellar ligament reflect the identical force that each attachment transmits. At the insertion of the quadriceps tendon and the 'origin' of the patellar ligament, there was more calcified tissue beneath the superficial than the deep parts of the attachment. This suggest that more force is transmitted through some parts of an attachment zone than others.

Glycol methacrylate embedding in diagnostic pathology. A standardized method for processing and embedding human tissue biopsy specimens

A standardized "low-cost" processing and embedding procedure is described for the preparation of semithin glycol methacrylate (GMA) sections of human tissue biopsy specimens for use in routine diagnostic pathology. The method is highly reliable and reproducible and is based on many years of experience in fundamental GMA research. The procedure combines the application of new, less toxic, plasticizers and the preparation of high-quality GMA mixtures. Microwave irradiation was used to improve staining qualities and to reduce staining times. An improved reticulin staining procedure is presented as well.

MR imaging of the normal and abnormal clivus

We retrospectively reviewed 330 T1-weighted sagittal images, 80 T2-weighted sagittal images, and 83 gadopentetate-dimeglumine-enhanced scans of normal adults to determine the MR appearance of the normal adult clivus. MR images of 21 patients with an abnormal clivus (19 with tumor invasion and two with marrow reconversion) were also evaluated retrospectively and compared with those of the control group to assess MR features distinguishing the two groups. Our study revealed that a normal adult clivus consisted of low- and high-intensity portions mixed in various proportions on T1-weighted images. The low-intensity portion was isointense or hyperintense relative to the pons and always contained foci of bright signal intensity. The low-intensity tumor of a pathologic clivus tended to be hypointense relative to the pons (17/19), and was completely devoid of foci of bright signal intensity. The normal adult clivus was approximately isointense relative to the pons on T2-weighted images. Clival tumors were grossly hyperintense relative to the pons on T2-weighted images in 11 of 17 patients. In the remaining six patients, either a portion of or the entire lesion was isointense relative to the pons and, therefore, was not detectable on T2-weighted images. A normal adult clivus can enhance to some degree (19/83). Clival tumors were found to enhance intensely. A clivus of very low signal intensity (signal void) on T1- or T2-weighted images was always abnormal. The clivus with marrow reconversion was uniformly hypointense relative to the pons on T1-weighted images and isointense relative to normal marrow on T2-weighted images. The intensity patterns of the normal clivus on T1- and T2-weighted MR images change predictably with advancing age. Intensity patterns of abnormal clivi differ from those of normal clivi. When contrast material is used, normal and abnormal clivi generally show different patterns of enhancement.

Magnetic resonance imaging of pediatric musculoskeletal trauma

MRI is an important tool for evaluating acute and chronic injuries to the musculoskeletal system. It is effective in demonstrating abnormalities in the knee and hips and in detecting bone and ligamentous trauma that is not evident radiographically.

[Magnetic resonance of the bone marrow]

Magnetic resonance imaging has opened new possibilities to current diagnostic radiology in the evaluation of bone marrow. In the past, bone marrow imaging was based on conventional radiology, nuclear medicine and computed tomography; they all exhibited some capabilities but also some limitations. Bone image on MR scans is due to bone marrow, with its different components of red and yellow marrow. Since red marrow is mostly liquid and yellow marrow contains large amounts of fat, the signal will vary, on T1-weighted images, according to their different proportions. There is a gradual change from red marrow to yellow marrow from birth to adulthood: this change determines the MR appearance of bone marrow, the different features of which should be known for a correct evaluation of pathologic findings. MRI is extremely effective in the evaluation of infiltrative disorders of bone marrow, such as leukemia, lymphoma, myeloma, primary and metastatic skeletal tumors, and infections. MRI allows depletive disorders of bone marrow and ischemic processes to be studied. Finally, MRI allows the non-invasive follow up of bone marrow pathologic conditions, thus representing a valid alternative to biopsy.

How do normal and leukemic white blood cells egress from the bone marrow? Morphological facts and biochemical riddles

Under normal circumstances only mature granulocytes and monocytes cross the bone marrow sinus wall, a trilaminar structure consisting of endothelial cells, a discontinuous basal membrane and an adventitial cell layer in order to get access to the blood circulation. In leukemia, however, immature white blood cells are able to traverse the barrier and to appear in the blood stream. Very little is known about the regulatory processes which govern the egress of white blood cells in healthy individuals and their malignant counterparts in patients with leukemia. The results of the few studies performed to address this question in animal and human leukemias all agree that the extent to which adventitial cells (fibroblasts) cover the endothelium in bone marrow is drastically reduced. This implies altered interactions between the leukemic and adventitial cells and their extracellular matrix. We propose here a model to explain the egress of normal cells and their leukemic counterparts. It is based upon our own experimental data and the general at present limited knowledge of the subject. It is hoped that this model will stimulate further research into this important aspect of leukemogenesis.

Comparative distribution of marrow CFU-e and CFU-gm progenitors in different anatomic sites in the dog

The interpretation of marrow cloning activity, particularly in serial cultures, is greatly influenced by the reproducibility of the collected marrow samples. In order to establish whether bone marrow cloning activities and precision of the cloning assays are influenced by the site of bone marrow collection in the dog, we studied the incidence of marrow erythroid (CFU-e) and granulocyte-macrophage (CFU-gm) progenitor cells in the iliac crest, sternum, vertebrae, femur, and humerus, using microplasma clot and soft agar culture systems. Marrow samples obtained from the femur and humerus revealed consistently higher cell concentrations than those from the iliac crest, vertebrae, or sternum. Those aspirated from the sternum and vertebrae had lower cell concentrations and were less reproducible. Statistical analysis revealed no significant differences in the incidence of marrow CFU-e and CFU-gm progenitor cells between the femur, humerus, iliac crest or vertebrae. With multiple sampling, the marrow cloning efficiency was consistent and reproducible within the individual dogs. We conclude that the distribution of CFU-e and CFU-gm is comparable throughout the active marrow in the dog and that these sites may be used interchangeably for multiple quantitative analysis of marrow hematopoietic progenitor cells.

Influence of fat on bone measurements with dual-energy absorptiometry

In order to investigate the influence of fat on bone in dual-energy absorptiometry measurements, we evaluated a special phantom on the three scanners: Lunar DP3, Lunar DPX and Hologic QDR-1000. The phantom employed hydroxyapatite blocks of various thicknesses to simulate bone, water to simulate muscle and lucite to simulate fat. The lucite plates were arranged in one and two layers in three different configurations: over the whole measurement area, over the hydroxyapatite blocks only and at both sides of the hydroxyapatite blocks. For all scanners, no influence of fat could be demonstrated if it was homogeneously distributed over the whole measurement area. However, changes in area bone-density were observed if fat was distributed inhomogeneously over the measurement area. Fat over only the bone area reduced the measured bone values by 0.051 g/cm2 per cm fat layer. Fat over only the soft-tissue area increased the measured bone values by the same amount. These results apply to the Lunar DPX scanner. The results for the Lunar DP-3 scanner are similar; those for the Hologic QDR-1000 show a slightly smaller fat dependence of 0.044 g/cm2 per cm fat layer. The fat influences are not dependent on the amount of bone and only minimally on the soft-tissue thickness. A change of 50% in the fat content of the bone marrow will change the measured area bone-density of an averaged sized vertebra by 5-6% depending on scanner model. Inhomogeneous fat distribution in soft tissue, resulting in a difference of 2 cm fat layer between soft-tissue area and bone area, will influence the measured area bone-density by 9-10%.

Bone reactions around transplanted roots. A 5-month quantitative study in dogs

The aim of this experiment was to study endosteal bone reactions around roots transplanted into an edentulous crest, and the role, if any, of periodontal ligament (PDL) remnants preservation. After extraction of premolars and healing of the crests, 20 roots in 5 dogs were transplanted into bone cavities prepared in the edentulous areas. Roots implanted in the lower and upper right cavities had their PDL remnants preserved while those grafted in the left cavities had their surface planed and dried. After 5 months, the roots with surrounding bone were removed. 2 bone areas were delineated at the mesial aspect of each root, one immediately adjacent to the alveolar wall and the other distal to it. Results demonstrated that bone volume was higher in the proximal versus distal area in the maxilla and mandible preserved groups. The adipocyte content of the marrow spaces, an index of bone maturation, was less pronounced in the proximal versus distal areas in the preserved groups. The number of osteoclasts was higher in the proximal zone in the preserved groups as were the extents of the different bone remodeling activities. The results indicate that the organization of PDL around transplanted roots is associated with rearrangement of the bone tissue surrounding the grafts. This process of long duration might be an adaptation to the likely low mechanical strains applied on bone through the root. Transplantation of PDL-damaged roots did not induce such events in the surrounding bone which had acquired the structure of an edentulous crest.

Red and yellow marrow in the femur: age-related changes in appearance at MR imaging

T1-weighted magnetic resonance (MR) images of the femur in 77 subjects, aged 1 month to 24 years, were retrospectively analyzed for the distribution and appearance of red and yellow marrow. The subjects were divided into six age groups, and the signal intensity and degree of mottling of marrow in the proximal epiphysis, proximal metaphysis, diaphysis, distal metaphysis, and distal epiphysis were observed and assigned a grade. Bone marrow with low or intermediate to slightly increased signal intensity was considered red marrow, while bone marrow with increased signal intensity was considered fatty marrow. An orderly progression of red to yellow marrow conversion in the femur was appreciated first in the diaphysis (ages 1-10 years) and then in the distal metaphysis (ages 10-20 years), with an adult pattern seen by age 24 years. The MR spectrum of red and yellow marrow differs from the existing macroscopic anatomical data because MR imaging is apparently more sensitive to the presence of microscopic fat in bone marrow.

Effect of trabecular bone on the appearance of marrow in gradient-echo imaging of the appendicular skeleton

This prospective study evaluated the effect of trabecular bone on the appearance of marrow in gradient-echo (GRE) images of the appendicular skeleton in vivo at high magnetic field strength. Magnetic resonance (MR) imaging of 10 normal extremities in five patients was performed with spin-echo (SE) and GRE sequences. The latter were obtained with gradient recalled acquisition in a steady state. SE and GRE sequences had identical spacing and planes of imaging. Cortical bone appeared as a signal void regardless of the pulse sequences and parameters. Marrow in contact with trabecular bone exhibited a shortened effective transverse relaxation time (T2*) and resultant signal loss because of local field inhomogeneities where mineralized matrix interfaced with it. This T2* effect was increased in regions with more trabecular bone (epiphysis) than regions with little trabecular bone (diaphysis). A low signal intensity on GRE images may represent fatty marrow with a high content of trabecular bone and should not be interpreted only as hematopoietic marrow.

Magnetic susceptibility effects of trabecular bone on magnetic resonance imaging of bone marrow

High-field spectroscopic studies at 5.88 tesla (T) indicate significant T2* shortening of water in suspensions of powdered bone, interpreted to be a result of magnetic susceptibility differences between bone particles and water. The authors investigated the effects of magnetic susceptibility differences between trabecular bone and water on magnetic resonance (MR) images at 0.6 T. The phantom was constructed of macerated intact trabecular human bone immersed in water. Although susceptibility-induced magnetic field inhomogeneities were detected by spectral line broadening by using an asymmetric spin-echo technique, the results show only a modest T2* shortening at this field strength. As expected, no T1 effect of trabecular bone was observed. Although susceptibility effects of trabecular bone may have a small impact on the signal intensity of MR images of bone marrow at midfield strength, the observed field strength dependence of these effects would predict significant susceptibility effects on clinical images at higher field strength.

Physiology of normal bone marrow

The bone marrow is a richly innervated and highly vascularized tissue of the body responsible for hematopoiesis. The major functions include transporting oxygen, defense against foreign invasion, and hemostasis. An uncommitted pluripotent stem cell undergoes proliferation and differentiation in an orderly fashion, producing immature committed progenitors. The progenitors ultimately produce mature committed cells that are released into the circulating blood. Cell production is controlled by a variety of regulatory mechanisms, including growth factors. The availability of recombinant growth factors has stimulated clinical trials of these factors in a wide variety of hematologic diseases.

One-dimensional spectroscopic imaging with stimulated echoes: phantom and human leg studies

One-dimensional phase encoding was incorporated in the stimulated echo single voxel localization sequence for in vivo proton spectroscopic studies. Phantom studies were performed to assess the effect of the number of phase encoding steps on the spectral contamination from the adjacent volumes. Both water suppressed and unsuppressed spectra were obtained in reasonable acquisition times from various regions in the human leg with a spatial resolution of around 1.1 cm3.

Star volume of marrow space and trabeculae in iliac crest: sampling procedure and correlation to star volume of first lumbar vertebra

The star volume is a new stereologic parameter which can describe structural changes of trabecular bone. It is defined as the mean volume of all the parts of an object which can be seen unobscured in all directions from a particular point inside the object. The mean is over all points inside the object. The parameter is only unbiased when Baddeley's vertical or isotropic sections are used. The star volume of the marrow space (V*m.space) and of the trabeculae (V*tr) was estimated on vertical sections obtained from the first lumbar vertebra and the iliac crest. The continued autopsy material presented was from 7 females and 11 males without malignant or metabolic bone diseases. The mean age was 52 years (range 7-87 years). The sampling procedure was as required for vertical sections and an anisotropic test system was used. A significant age-related increase was shown in marrow space star volume in both lumbar vertebra and iliac crest. The increase in lumbar vertebra marrow space star volume was significantly greater for women than for men. Moreover, a significant correlation was found between the marrow space star volume in lumbar vertebra and iliac crest (r = 0.72, 2p less than 0.01). No such relation was found for trabecular star volume which did not change with age. The results also revealed that marrow space star volume could be measured on conventional bone biopsies preferably, however, on two mutually perpendicular vertical section planes.

In vitro effect of copper on the stromal cells of bone marrow in rats

The effect of copper in form of copper sulphate (CuSO4 x 5 H2O) was studied in the bone marrow cells of rats of Wistar strain in an in vitro culture. Evident differences between tissue cultures of the bone marrow cells were observed between the control and experimental groups. In the experimental group, the CFU-F colonies appeared as early as in 3rd day while in the control group in 5th day. Loosely arranged fibroblasts, macrophages and adipocytes also showed quantitative differences between groups. An increase in mean corpuscular hemoglobin (MCH) was also found in peripheral blood of experimental animals.

Magnetic resonance imaging of bone marrow: diagnostic value in diffuse hematologic disorders

Magnetic resonance imaging (MRI) has value in characterizing normal and abnormal bone marrow because of its ability to distinguish fat from other tissues. Due to this advantage, hematologic disorders resulting in alterations of the normal cellular and fatty marrow distribution can be appreciated. In this article, the role of MRI in diffuse hematologic disorders is emphasized. At birth, almost all marrow is cellular, but by age 25, cellular marrow is restricted to the axial skeleton and proximal femoral and humeral metaphysis. The remainder is fatty, consisting of 80% fat, 15% water, and 5% protein. With increased need for hematopoiesis, reconversion from fatty to cellular marrow occurs in many diffuse disease states. Diffuse diseases that affect bone marrow production are divided into four categories representing conditions that affect the pluripotent hematopoietic stem cell. These include stem cell failure resulting in aplastic anemia, uncontrolled stem cell proliferation as exemplified by polycythemia vera, stem cell dysplasia such as sickle cell anemia, and malignant transformations or replacement. The MRI appearance of these disorders is discussed in this article. The use of spin-echo (SE) sequences is the most common approach to bone marrow imaging. With T1-weighted SE images, fatty marrow will appear bright and cellular marrow, with lower fat content, will exhibit a lower density signal. With T2-weighted SE pulse sequences, contrast between fatty marrow and cellular marrow decreases. Contrast between fatty and cellular marrow is enhanced with chemical shift imaging, including Dixon out-of-phase imaging, as emphasized in this article. MRI presents a more global view of the bone marrow than biopsy material and should provide a better understanding of diffuse hematologic disease progression and resolution.

Contrast manipulation and artifact assessment of 2D and 3D RARE sequences

The extent of contrast manipulation and the assessment of characteristic artifacts in imaging studies of brain and knee as performed with novel variants of the Rapid Acquisition Relaxation Enhanced (RARE) sequence are reported. Methods of ordering the phase encoding within one or two echo trains are proposed for manipulating T2 contrast. Options for minimizing artifacts associated with the various schemes are discussed. The extent of T1 contrast manipulation in RARE sequences is explored by varying repetition rates in a signal averaging scheme and by applying inversion pulses prior to data acquisition. The results demonstrate that RARE sequences can be utilized for obtaining good quality images with a range of tissue contrast options similar to those associated with slower spin-echo methods. They also suggest that RARE applications need not be confined to highlighting long T2 fluid spaces, an application already well documented.

The foci of the red bone marrow observed in the laryngeal cartilages of the Suncus murinus

In the Suncus murinus, the thyroid, the cricoid and the arytenoid cartilages were in part ossified. The foci of the red bone marrow, termed as the "marrow foci", were observed in the ossified portion of the cartilages. The marrow foci were filled with mature and immature blood cells. It is suggested that the marrow foci take part in active hematopoiesis in the Suncus. Further, a canal which connected the marrow cavity and the outside of the cartilage was occasionally seen. It seems that the canal corresponds to the nutrient canal.

Dietary boron modified the effects of magnesium and molybdenum on mineral metabolism in the cholecalciferol-deficient chick

The metabolic effects of dietary boron, magnesium, and molybdenum on mineral metabolism in the cholecalciferol-deficient chick, with emphasis on growth cartilage histology, were studied. One-day-old cockerel chicks were assigned to groups in a fully-crossed, three factor, 2 x 2 x 2 design. The basal diet was based on ground corn, high-protein casein, and corn oil and contained 125 IU cholecalciferol (inadequate), 0.465 mg B, 2.500 mg Mg, and 0.420 mg Mo/kg. The treatments were the supplementation of the basal diet with B at O or 3; Mg at 300 (inadequate) or 500 (adequate); and Mo at 0 or 20 mg/kg. At d 25, B depressed mortality, alleviated the cholecalciferol-deficiency induced distortion of the marrow sprouts (MS) of the proximal tibial epiphysial plate, and elevated the numbers of osteoclasts within the MS. Adequate Mg exacerbated the cholecalciferol-deficiency induced bone lesions. Mo widened the MS markedly. In Mg-deficient chicks, B elevated plasma Ca and Mg concentrations and growth, but inhibited initiation of cartilage calcification; B had the opposite effect in Mg-adequate chicks. An interaction among B, Mg, and Mo affected plasma uric acid and glucose concentrations. B may function to modify mineral metabolism in cholecalciferol deficiency, suppressing bone anabolism in concurrent Mg deficiency and bone catabolism in concurrent Mg adequacy.

Improvement in signal-to-noise ratio and reduction of chemical shift and motion-induced artifacts by summation of gradient and spin echo data acquisition

Narrow bandwidth magnetic resonance (MR) imaging allows an increase of signal-to-noise ratio (SNR) but causes increased chemical shift and motion-induced artifacts. To obtain MR images with SNR approximately equal to that obtained with narrow bandwidth but with less chemical shift and motion-induced artifact, we introduced triple readout gradient reversal centered around the spin echo. As a result, signals from two gradient echoes and a single spin echo can be collected and summed. Phantom, knee, shoulder, and abdominal MR images were obtained using a 1.5 T GE Signa System at sampling rates ranging from 10 to 60 kHz. Since the bandwidth per pixel was tripled, chemical shift misregistration was reduced by the same factor. The summation image of two gradient echoes and one spin echo had an SNR comparable with that of a single spin echo acquired within the same total sampling interval. Data acquisition at a high sampling ratio also minimizes the dispersion of T2* weighting among three echoes. In addition, summation of the three resulting images decreases motion artifact by effective averaging.

Magnetic resonance imaging of bone marrow in lymphoproliferative disorders: correlation with bone marrow biopsy

In a prospective clinical study 10 normal volunteers and 30 patients with lymphoma--11 patients with Hodgkin's lymphoma and 19 patients with non-Hodgkin's lymphoma (11 low grade, 8 high grade)--were examined. Proximal femora, pelvis and lumbar spine were imaged with a 1.5 tesla superconducting MR imaging system (Siemens Magnetom). Areas of malignant infiltration in the bone marrow were clearly detected by visual and/or quantitative assessment. In most cases bone marrow involvement was demonstrated by both magnetic resonance imaging and bone marrow biopsies. However, in three of 30 patients magnetic resonance imaging showed evidence of lymphomatous involvement despite normal bone marrow histology. In one patient bone marrow cytology revealed malignant infiltration in the absence of MRI abnormalities. Thus, MRI is a sensitive method for detecting bone marrow infiltration by lymphoma.

Marrow conversion before pneumatization of the sphenoid sinus: assessment with MR imaging

To evaluate the bone marrow change before pneumatization of the sphenoid sinuses in childhood, the authors retrospectively reviewed short repetition time/echo time midsagittal magnetic resonance images in 56 patients younger than 6 years. The signal intensity of the presphenoid bone marrow (anteromedial part of the sphenoid bone) was as low as that of muscle (grade 1) and remained the same as that of the basisphenoid and basiocicput in all infants (n = 6) younger than 6 months. Between 7 months and 2 years, most patients (24 of 27) exhibited fatty conversion of bone marrow limited to the presphenoid (grade 2). After 3 years of age, most patients demonstrated pneumatization (six of 12 at 3-4 years, eight of 11 at 5-6 years) in addition to the grade 2 findings (grade 3). The presphenoid exhibits signal intensity characteristics of fatty marrow before it is invaginated by the developing sphenoid sinus. Fatty change before pneumatization is a normal developmental process and should not be misinterpreted as a pathologic condition.

Cranial bone marrow in children: assessment of normal development with MR imaging

Magnetic resonance images of cranial bone marrow in 238 patients (246 examinations) less than 25 years old were reviewed to establish normal age-related standards. Bone marrow in the clivus and calvaria had uniformly low signal intensity (grade 1) on T1-weighted images in most infants less than 1 year old. The number of patients with grade 1 marrow decreased rapidly in early childhood, while the number of patients with marrow of low and high signal intensity (grade 2) and uniformly high signal intensity (grade 3) gradually increased with age. A grade 1 marrow was no longer observed in either the clivus or calvaria after age 7. Most patients had a grade 3 marrow by age 15. Because bone marrow in certain pathologic conditions has decreased signal on T1-weighted images and therefore resembles grade 1 or 2 appearances of normal marrow in children, these results may be useful for differentiating normal and abnormal bone marrow signal intensities in infants and children.