Comparison of immunoscintigraphy and colloid scintigraphy of bone marrow

Age-Related Changes in the Metabolic Activity and Distribution of the Red Marrow as Demonstrated by 2-Deoxy-2-[F-18]fluoro-d-glucose-Positron Emission Tomography

OBJECTIVES

The objective of the study was to determine age-related changes occurring in red marrow with regard to its distribution and the degree of its metabolic activity by whole-body 2-deoxy-2-[F-18]fluoro-D-glucose (FDG)-positron emission tomography (PET).

METHODS

This retrospective study included 112 patients (56 male, 56 female, mean age 40 years, range 2-85) who underwent whole-body FDG-PET scans for assessment of disorders that were determined not to affect red marrow activity. These patients were categorized into the following groups with equal gender distribution: 0-15 years (12 individuals), 16-25 years (20), 26-35 years (10), 36-45 years (20), 46-55 years (14), 56-65 years (16), 66-75 years (14), and 76-85 years (6). Whole-body FDG-PET images were performed at 60 min after the intravenous administration of 0.14 mCi/kg of FDG. By employing a dedicated whole-body PET scanner. Maximal standardized uptake value (SUV(max)) was calculated from three consecutive transverse sections of the upper thirds of the humeri and femora, manubrium of the sternum, 12th thoracic and 5th lumbar vertebra and anterior superior iliac crests of the pelvis. All available results from other imaging examinations [magnetic resonance imaging (MRI), computed tomography (CT), and conventional radiolography], laboratory data, biopsies, and the clinical course of these subjects were reviewed to make certain that the bone marrow sites examined were free of any known pathologies.

RESULTS

SUV(max) in the extremities showed significant decline with aging (correlation coefficient of -0.60 to -0.67, p < 0.01). In contrast, a weak correlation was noted in the axial skeletal activity with advancing age (correlation coefficient of -0.28 to -0.48, p < 0.05).

CONCLUSIONS

These data suggest that FDG metabolic activity of the red marrow in the extremities decline significantly with normal aging, while that of the axial skeleton show minimal decrease related to this biologic phenomenon. These findings are of value in assessing the effects of hematological and other disorders in the distribution and the metabolic activity of this important tissue and testing therapeutic interventions that are employed for treating such maladies.

Structural and functional imaging of normal bone marrow and evaluation of its age-related changes

A number of noninvasive imaging techniques have been used for the evaluation of bone marrow, including magnetic resonance imaging (MRI) and bone marrow scintigraphy. The appearance of bone marrow on MRI varies considerably depending on the proportion of red and yellow marrow, and the composition of the red marrow and its distribution with relation to age and sex. The composition of bone marrow also can vary under physiological and pathological conditions. MRI is a highly sensitive technique for evaluating the bone marrow, but it is limited in its practical use for whole-body bone marrow screening. Bone marrow scintigraphy with radiolabeled compounds such as technetium-99m-labeled nanocolloid and monoclonal antibodies has the advantage of evaluating the entire bone marrow, and has been used for the diagnosis of various bone marrow disorders. In addition, (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) imaging can be used to evaluate bone marrow metabolism and disease and to provide information about the state of the primary tumor, lymph nodes, and distant metastases. Understanding of the appearance of normal bone marrow, including age- and sex-specific differences with each of these imaging modalities, is essential to permit accurate diagnosis of benign and malignant bone marrow disorders. We present a review of MRI and scintigraphy of normal bone marrow with some emphasis on FDG-PET imaging in assessing marrow activity in normal and abnormal states and also present preliminary data regarding normal age-related changes in bone marrow through use of FDG-PET, as well as the role of segmentation of bone marrow on MRI for quantitative calculation of the metabolic volumetric product for red marrow metabolism using FDG-PET.

Bone marrow immunoscintigraphy in haematological patients with pancytopenia: preliminary results

The aim of this study was to assess the clinical value of bone marrow immunoscintigraphy using the (99m)Tc labelled anti-NCA-95 antigranulocyte antibodies (AGAb) and of AGAb bone marrow uptake ratio (UR) in the initial diagnostic work-up of diseases with depression of the bone marrow. Twenty-four whole-body bone marrow scans were performed in 23 patients (11 women, 12 men; median age 46 years, range 17-74 years) 5 h after i.v. injection of 370 MBq of AGAb. The UR was calculated from the posterior view drawing an irregular region of interest around the sacroiliac and a background areas. The mean UR in pancytopenic patients was 2.3+/-1.5 (range 0.3-5.8), thus being significantly lower (P=0.45 x 10(-6)) than the mean UR in a control group of 50 patients (mean UR 7.3+/-2.3; range 4.4-12.6) obtained previously. Considering patient age, there was no overlap between UR of pancytopenic patients and the respective normal ranges. The bone marrow appearance on scans seemed to be characteristic for the different haematological diseases investigated. In six patients with myelofibrosis, bone marrow scans demonstrated diffusely decreased bone marrow activity and prominent splenic uptake, possibly related to extramedullary haematopoiesis. In aplastic anaemia, highly reduced and patchy marrow uptake was observed in four patients (five scans), in one of them persisting even after blood cell counts had recovered to the near-normal range. In another two patients with aplastic anaemia, diffusely decreased bone marrow uptake was obtained. In patients with myeloid leukaemia, bone marrow patterns were almost normal probably because the target antigen is often expressed on neoplastic myeloid cells, too. Bone marrow extension was a common finding in these patients. There is an obvious differentiation between haematological patients with pancytopenia and normal subjects by means of AGAb bone marrow uptake ratio. The distinct patterns of AGAb distribution may be indicative for particular haematological diseases.

Bone marrow scintigraphy with 99m Tc labelled monoclonal anti-NCA 90 Fab' fragment: a feasibility study and comparison of bone marrow uptake with 99m Tc labelled monoclonal anti-NCA 95 antigranulocyte antibody

The aim of this retrospective study was to evaluate the usefulness of 99mTc labelled monoclonal anti-NCA 90 antigranulocyte antibody Fab' fragment (MN3 Fab') as a bone marrow imaging agent. One hundred and ten planar scans (88 patients) of the lumbar and sacroiliac regions as well as whole-body scans were performed after 1, 5 and 24 h. All the scans were evaluated visually and bone marrow uptake was determined semiquantitatively as count density ratio from sacroiliac-minus-background to background area. Results were compared to 50 age-matched patients with normal bone marrow scans obtained with the intact 99mTc labelled monoclonal anti-NCA 95 antigranulocyte antibody (BW 250/183) in a previous study. Seventy-three patients showed a physiological activity distribution in the central bone marrow. Ten patients showed a bone marrow extension, while in two patients central bone marrow depression was observed. Evaluation of the ribs, lower thoracic and upper lumbar spine was hampered by soft-tissue activity. Bone marrow uptake was 1.36+/-0.56 after 1 h, decreased thereafter and was significantly lower than that of BW 250/183 (P < 0.001). In conclusion, MN3 Fab' cannot be recommended for bone marrow scintigraphy, because relevant parts of the haemopoietically active bone marrow are not accessible to visual evaluation. A significant role of the semiquantitative evaluation of MN3 Fab' bone marrow uptake in patients with potential marrow depression seems unlikely.

Bone marrow scintigraphy using technetium-99m antigranulocyte antibody in malignant lymphomas

BACKGROUND

The purpose of this study was to elucidate the clinical reliability of immunoscintigraphy (IS) to detect infiltration of the bone marrow in patients with malignant lymphoma.

PATIENTS AND METHODS

Whole body IS was performed in 103 patients with Hodgkin's disease (HD) or non-Hodgkin's lymphoma (NHL) using Tc-99m labelled anti-NCA-95 which allows visualization of the granulopoietic bone marrow. Of these, 52% were studied prior to any therapy. Findings were compared to posterior iliac crest biopsy as well as MRI and/or follow-up examination. Criteria of marrow infiltration were a positive biopsy, positive follow-up, or positive results of MRI.

RESULTS

Comparison of IS and biospy revealed concordant findings in 69 and discordant findings in 34 of 103 patients. Of the 34 patients with discordant results, IS showed lesions suspicious of bone marrow infiltration in 29 patients despite normal biopsy findings. When follow-up and additional examinations were taken into consideration, 10 patients remained with probably false positive and five with false negative IS findings. IS proved to be highly sensitive and specific in patients with HD (100% and 84%, respectively) and high-grade NHL (93% and 84%, respectively). Moderate sensitivity (60%) was found in low-grade NHL. This was possibly due to false negative IS in three to five patients with chemotherapy in contrast to one of five false negative results in patients without chemotherapy.

CONCLUSION

Bone marrow scintigraphy using antigranulocyte antibodies is highly sensitive in HD and high-grade NHL. Positive findings in IS subsequent to a negative biopsy should be followed by guided re-biopsy or MRI.

Tc-99m MIBI localization in bone marrow: a marker of bone marrow malignancy

To determine the potential of Tc-99m MIBI for detecting bone marrow malignancy, MIBI imaging of the femur was evaluated. There was no detectable MIBI activity in 125 of 141 (89%) control patients. Clearly demonstrated focal or tubular MIBI activity indicating intramedullary accumulation was demonstrated in 44 of 45 (98%) patients with proven marrow malignancy: 9 patients with multiple myeloma, 10 patients with malignant lymphoma, 11 patients with acute leukemia, 1 patient with chronic leukemia, and 14 patients with skeletal metastases. No abnormal MIBI activity was observed in the femur in 19 of 22 (86%) patients who had no evidence of malignant involvement in the femoral marrow, in 3 patients with solitary plasmacytomas of the spine, sternum or iliac bone, or in 16 patients with malignant lymphoma. In 12 of 24 patients with acute leukemia in complete remission, no abnormal MIBI accumulation was shown in the femur, but in 12 patients, abnormal accumulation indicating residual leukemic activity was demonstrated. MIBI imaging correlated extremely well with MRI studies; 26 of 28 patients with focal or tubular increased MIBI activity in the femur showed decreased signal on T1-weighted images and a high signal on short inversion recovery images, and 11 patients with no abnormal activity showed a high signal on T1 images. MIBI imaging of the femoral bone marrow may be a new modality for detecting marrow malignancy.

Different biodistribution of 99mTc-labelled chimeric mouse-human monoclonal antibody between athymic mice model and human

Biodistribution of chimeric mouse/human monoclonal antibody against non-specific cross-reacting antigen (chNCA Ab) was studied in athymic mice and patients with metastatic bone disease. 99mTc-chNCA Ab showed a high labelling efficiency, stability and also a high binding ratio to human granulocytes. Since NCA showed cross-reactivity with carcinoembryonic antigen (CEA), animal experiments showed that 99mTc-chNCA Ab was accumulated in the xenografted tumour which expressed CEA, suggesting the preserved immunoreactivity of labelled materials. In the clinical study, injected 99mTc-chNCA Ab formed a high molecular weight complex immediately after intravenous administration and was trapped mainly in liver. The first-phase plasma half-life was 6.4 +/- 1.1 min. None of the patients showed adverse reaction or human antimurine or anti-chimeric antibody in their serum. 99mTc-chNCA Ab demonstrated remarkably different biodistribution between patients and the animal model and showed different pharmacokinetics from other murine and chimeric Abs reported previously. For safety HPLC analysis should be performed before clinical radioimmunodetection or radioimmunotherapy by incubating radiolabelled MAb with human serum under strict conditions.

Generalized bone marrow metastases. High liver uptake on bone marrow immunoscintigraphy associated with extramedullary hematopoiesis

Increased hepatic uptake and absent bone marrow uptake on bone marrow immunoscintigraphy has been reported after the formation of human antimurine antibodies. A case of generalized bone marrow metastases is presented, in whom an elevated liver uptake on bone marrow immunoscintigraphy proved to be associated with extramedullary hematopoiesis. Extramedullary hematopoiesis should be included as a possible cause of a disproportionately elevated liver uptake on bone marrow immunoscintigraphy, especially on initial studies, or on repeat studies with low human antimurine antibody titers. Tc-99m labeled BW 250/183 immunoscintigraphy may aid in the localization of suspected sites of extramedullary hematopoiesis.

Scintigraphic evaluation of the haemopoietic bone marrow using a 99mTc-anti-granulocyte antibody: a validation study with 52Fe

To specify the validity of bone marrow scanning using a monoclonal anti-granulocyte antibody labelled with 99mTc (BW 250/183) for the functional assessment of haemopoiesis, we compared this method with 52Fe scan in 16 patients with haematological disorders. The examinations were performed using a rectilinear whole-body scanner and the distribution of the two tracers was assessed visually and quantitatively in anatomical bone marrow segments, the spleen and liver. Qualitative comparison showed concordance in the bone marrow distribution of the two tracers in 83% of the segments. Discrepancies were found in six patients with hypoplastic or aplastic marrow. The spleen was visualized in all cases with the 99mTc-Moab, including nine patients without splenic haemopoiesis (i.e. without spleen uptake of 52Fe). The uptake of the two tracers, quantified in bone marrow segments and the spleen, correlated well (P < 0.001), but not in the liver (NS). The correlation between the uptake values for each patient was excellent, except in cases of aplastic bone marrow. In conclusion, bone marrow scanning using a 99mTc labelled anti-granulocyte monoclonal antibody enables functional evaluation of the distribution of haemopoiesis. Limitations include the evaluation of bone marrow aplasia and identification of splenic haemopoiesis, for which 52Fe remains the tracer of choice.

The value of bone scintigraphy, bone marrow scintigraphy and fast spin-echo magnetic resonance imaging in staging of patients with malignant solid tumours: a prospective study

The purpose of this prospective study was to define the value of bone scintigraphy (BS), bone marrow scintigraphy (BMS) and the new fast spin-echo (FSE) magnetic resonance imaging (MRI) sequences in screening for bone metastases in patients with solid malignant tumours. It was our particular interest to classify patients into a group with and a group without bone metastases, and not only to compare the absolute number of metastases detected by each method. Thirty-two patients were examined using technetium-99m dicarboxy propane diphosphonate bone scintigraphy, 99Tc-labelled monoclonal anti-granulocyte antibodies for bone marrow scintigraphy and 1.5 T MRI using T1-weighted and FSE T2-weighted sequences. Against a reference standard obtained by re-evaluation of all clinical and imaging data 1 year after prospective BS, BMS and MRI had been performed, the three imaging modalities were falsely positive in two, eight and two cases and falsely negative in zero and four cases, respectively. BMS was falsely positive in eight patients because of vertebral marrow degeneration which caused photopenic defects which could not be differentiated from metastases. MRI showed these lesions to unequivocally contain fat. BMS and MRI were falsely negative in four cases because of the limited field of examination. In our study the key factor in classifying a patient as bone M1 or M0 was the possibility of surveying the entire skeleton, as is the case in BS, and not that MRI had a higher sensitivity compared to BS when analysis was on a lesion-by-lesion basis.(ABSTRACT TRUNCATED AT 250 WORDS)

Recent advances in bone marrow scanning

Interest in bone marrow scanning has been renewed as the result of the development of radiopharmaceuticals for evaluating specific aspects of bone marrow anatomy, physiology and pathology. This article provides a brief review of bone marrow structure, blood flow and function essential to the understanding of basic principles of bone marrow radionuclide imaging. The prospects and limitations of imaging haematopoietic bone marrow in man using indium 111 chloride, technetium-99m (99mTc)-labelled microcolloid or 99mTc-labelled monoclonal antigranulocytic and antimyelocytic antibodies are discussed in more detail. The technical aspects of bone marrow scintigraphy are presented. Results of more recent studies evaluating bone marrow scanning in circulatory, inflammatory and in systemic haematological disorders are summarized. Special attention is paid to the concept of bone marrow micrometastases and its implications for the follow-up of patients with malignant tumours. Recent results suggest that immunoscintigraphy of bone marrow may provide a novel and sensitive approach for establishing the presence and extent of bone marrow infiltration.