Bone scanning: radionuclidic reaction mechanisms

False Positive in [ 99m Tc]Tc-DPD Scintigraphy for Cardiac Amyloidosis Due to Intravenous Iron Administration

ABSTRACT

[ 99m Tc]Tc-DPD (3,3-diphosphono-1,2-propanodicarboxylic acid) scintigraphy is an essential tool for diagnosing transthyretin amyloid cardiac amyloidosis. An 86-year-old woman suffering from heart failure with preserved ejection fraction underwent [ 99m Tc]Tc-DPD scintigraphy and a SPECT/CT for suspected transthyretin amyloid cardiac amyloidosis. The scan showed intracardiac and liver uptake. As the patient had taken intravenous iron on the morning of the scan, we decided to repeat the scan, but this time, it showed no uptake in the heart or the liver. Accordingly, we concluded the first result was a false positive due to drug interaction.

A multicentre simulation study of planar whole-body bone scintigraphy in Sweden

Background

Whole-body bone scintigraphy is a clinically useful non-invasive and highly sensitive imaging method enabling detection of metabolic changes at an early stage of disease, often earlier than with conventional radiologic procedures. Bone scintigraphy is one of the most common nuclear medicine methods used worldwide. Therefore, it is important that the examination is implemented and performed in an optimal manner giving the patient added value in the subsequent care process. The aim of this national multicentre survey was to investigate Swedish nuclear medicine departments compliance with European practice guidelines for bone scintigraphy. In addition, the effect of image acquisition parameters on the ability to detect metabolic lesions was investigated.

Methods

Twenty-five hospital sites participated in the study. The SIMIND Monte Carlo (MC) simulation and the XCAT phantom were used to simulate ten fictive patient cases with increased metabolic activity distributed at ten different locations in the skeleton. The intensity of the metabolic activity was set into six different levels. Individual simulations were performed for each site, corresponding to their specific camera system and acquisition parameters. Simulated image data sets were then sent to each site and were visually evaluated in terms of if there was one or several locations with increased metabolic activity relative to normal activity.

Result

There is a high compliance in Sweden with the EANM guidelines regarding image acquisition parameters for whole-body bone scintigraphy. However, up to 40% of the participating sites acquire lower count density in the images than recommended. Despite this, the image quality was adequate to maintain a stable detection level. None of the hospital sites or individual responders deviated according to the statistical analysis. There is a need for at least 2.5 times metabolic activity compared to normal for a lesion to be detected.

Conclusion

The imaging process is well harmonized throughout the country and there is a high compliance with the EANM guidelines. There is a need for at least 2.5 times the normal metabolic activity for a lesion to be detected as abnormal.

Dosimetry of bone seeking beta emitters for bone pain palliation metastases

Amongst cancer patients, bone pain due to skeletal metastases is a major cause of morbidity. A number of beta-emitting radiopharmaceuticals have been used to provide internal radiotherapy of bone metastases and provide palliative pain relief. In this article we describe the different physical characteristics of the various beta emitting radionuclides which have been used in this clinical setting and the potential impact of differences in dose-rate on radiobiological outcomes. A detailed review of the biodistribution of these treatments, based on both in-vivo clinical investigations and post mortem autoradiography assessments is provided. These treatments result in physiological delivery of radiation doses to the target disease as well as to critical healthy organs. Particular attention is paid to the radiation doses received by normal bone tissue, bone marrow as well as metastatic bone disease. The underlying models of radiation transport within bone and bone marrow are reviewed alongside the practical steps that must be taken to acquire and analyse the information require for clinical dosimetry assessments. The role of whole body measurements, blood and faecal assays as well as both planar and tomographic gamma camera imaging are considered. In addition we review the rationale for allocating measured bone uptake between trabecular and cortical bone tissue. The difference between bone volume and bone surface seeking radiopharmaceuticals are also discussed. This review also extends to the development of preclinical models of bone metastases which may inform future dosimetric calculations. Finally, we also present a comprehensive review of the dosimetry of the established treatments ⁸⁹Strontium-chloride; ³²Phosphorus; ¹⁸⁸Rhenium-hydroxyethylidine disphosphonate; ¹⁸⁶Rhenium-1,1-hydroxyethylidene disphosphonate (¹⁸⁶Re-HEDP); ¹⁵³Samarium-ethylenediaminetetramethylene phosphonate; as well as the emerging treatments ¹⁸⁸Rhenium-zoledronic acid; ¹⁸⁸Rhenium-ibedronat; ¹⁷⁷Lutetium-zoledronic acid; and ¹⁷⁷Lutetium ethylenediaminetetramethylene phosphonate. This review highlights not only the inter treatment differences in the radiation absorbed doses delivered to metastatic disease by different radiopharmaceuticals but also the intra treatment differences which result in a large range of observed doses between patients.

Radiotracers for Bone Marrow Infection Imaging

INTRODUCTION

Radiotracers are widely used in medical imaging, using techniques of gamma-camera imaging (scintigraphy and SPECT) or positron emission tomography (PET). In bone marrow infection, there is no single routine test available that can detect infection with sufficiently high diagnostic accuracy. Here, we review radiotracers used for imaging of bone marrow infection, also known as osteomyelitis, with a focus on why these molecules are relevant for the task, based on their physiological uptake mechanisms. The review comprises [67Ga]Ga-citrate, radiolabelled leukocytes, radiolabelled nanocolloids (bone marrow) and radiolabelled phosphonates (bone structure), and [18F]FDG as established radiotracers for bone marrow infection imaging. Tracers that are under development or testing for this purpose include [68Ga]Ga-citrate, [18F]FDG, [18F]FDS and other non-glucose sugar analogues, [15O]water, [11C]methionine, [11C]donepezil, [99mTc]Tc-IL-8, [68Ga]Ga-Siglec-9, phage-display selected peptides, and the antimicrobial peptide [99mTc]Tc-UBI29-41 or [68Ga]Ga-NOTA-UBI29-41.

CONCLUSION

Molecular radiotracers allow studies of physiological processes such as infection. None of the reviewed molecules are ideal for the imaging of infections, whether bone marrow or otherwise, but each can give information about a separate aspect such as physiology or biochemistry. Knowledge of uptake mechanisms, pitfalls, and challenges is useful in both the use and development of medically relevant radioactive tracers.

Rare Case of Diffuse Splenic Uptake on Methylene Diphosphonate Bone Scan in a Patient with Sickle Cell Disease

Extraskeletal tracer uptake in methylene diphosphonate (MDP) bone scan is not a common finding. There have been several case reports in the literature showing diffuse splenic uptake in MDP bone scan. We present a case of sickle cell disease, which showed diffuse splenic uptake on MDP whole-body bone scan.

Osteomyelitis of the Thumb in a 21-Year-Old Chiropractic Patient: A Case Report

OBJECTIVE

The purpose of this case report is to describe the presentation of a patient with osteomyelitis of the thumb.

CLINICAL FEATURES

A 21-year-old man presented with painful, red, and edematous thumb pain over the anterior and posterior surface for a duration of 4 days. The patient reported no trauma or recent operation. The patient was treated conservatively for capsulitis. The patient's symptoms worsened within 2 days, and he was referred for additional imaging consisting of a bone scan. The bone scan showed increased uptake, resulting in a change of diagnosis to suspected osteomyelitis. The patient was referred to a medical doctor for care that consisted of antibiotics and physiotherapy.

INTERVENTION AND OUTCOME

Despite treatment, the patient had some mild permanent damage to the range of motion of the joint and soft tissue volume loss.

CONCLUSION

This case demonstrates the importance of considering osteomyelitis as a differential diagnosis. Amputation was avoided for this patient because of the early recognition and referral.

SPECT/CT in Postoperative Foot and Ankle Pain

Postoperative pain is a clinically relevant issue in orthopedic patients, affecting more than 40% 1 year after foot and ankle surgery. Because of the very complex anatomy with many different joints and several motion axes, clinical examination and conventional imaging are sometimes not sufficient to identify a local pain generator. Local uptake of bone-seeking radiopharmaceuticals is known to correlate accurately with sites of pain generating foci and, thus, bone scintigraphy has been an established method to evaluate these respective patients for many years. However, the specificity is rather low if only planar images are acquired. The development of SPECT and especially of hybrid SPECT and CT imaging has significantly enhanced the specificity of this technique. The combination of both functional and morphological imaging, ideally performed with a dedicated SPECT/CT system to minimize misregistration owing to motion artifacts and to enhance image quality by attenuation correction, allows an early and reliable detection of pathologic bone processes, even in patients where radiological imaging with MRI or CT is hampered by metal implants. In diabetic patients with a neuropathic Charcot osteoarthropathy, infection can be differentiated from inflammatory bone alterations (causing bone marrow edema) almost certainly using SPECT/CT with radiolabeled white blood cells and antigranulocyte antibodies, allowing an individual and precise treatment planning either in the initial course of the disease or even after surgery. This article reviews the most frequent clinical challenges in patients after foot and ankle surgery, including a description of the various surgical procedures, the different imaging options with their advantages and disadvantages, and aims to integrate bone SPECT/CT into the clinical diagnostic workup.

Evaluation of the Scintigraphic Technique for Detecting Bone Metastases in 100 Breast Cancer Patients

In an attempt to evaluate the utility of bone scintigraphy for the diagnosis and follow-up of skeletal metastases, radioisotopic scan (total body) by 99mTc has been performed on 100 patients suffering from breast cancer in various stages. The radiographic control followed the scan on the basis of clinical or scintigraphic suspicion of bone lesions. Twenty-one patients showed metastases by scan, and in all but 2 the radiography was concordantly positive; in 22 subjects scintigraphy and radiology demonstrated non-malignant lesions. Both scan and radiology were used to explore 169 metastatic localizations, with concordant results in 45% of the sites; however, 7% of the sites with discordant results became positive for metastasis by radiology some months after the scan positivity. The false–negative results were more frequent in the radiographic study (27%) than with the scintigraphic scan (21%). The latter technique was unable to detect osteoblastic lesions in particular. The scintigraphic test also gave reliable results in the follow-up procedure, frequently anticipating the radiological modifications of metastatic lesions. In conclusion, bone scan often appears to be more accurate and precocious than the roentgengraphic test in the detection and the follow-up of skeletal metastatic lesions; it suggests the utility of the bone scan as a preliminary test, which allows a more rational use of the radiology.

Altered Biodistribution of 99mTc-DPD on Bone Scan After Intravenous Iron Supplement

We report a case with altered biodistribution of ^99mTc-dicarboxypropane diphosphonate (^99mTc-DPD) on whole body bone scan after intravenous iron supplement therapy. A 47-year-old male patient who had recently been detected with a hepatic mass suggestive of hepatocellular carcinoma underwent bone scan as staging work-up before surgery. Bone scan images at 3 h after injection of ^99mTc-DPD demonstrated unusually increased blood pool activities in the heart, liver, and spleen with usual skeletal uptakes. The patient had been treated for severe anemia from hemorrhoid with two intravenous administration of ferric hydroxide carboxymaltose complex at approximately 22 h and 2 h prior to the ^99mTc-DPD injection, which we consider as the most probable cause of altered biodistribution of ^99mTc-DPD.

Comparison of hybrid 68Ga-PSMA-PET/CT and 99mTc-DPD-SPECT/CT for the detection of bone metastases in prostate cancer patients: Additional value of morphologic information from low dose CT

PURPOSE

This study compared ⁶⁸Gallium-prostate-specific-membrane-antigen based Positron-emission-tomography (⁶⁸Ga-PSMA-PET) and ^99metastabletechnetium-3,3-diphospho-1,2-propanedicarbonacid (^99mTc-DPD-SPECT) in performing skeletal staging in prostate cancer (PC) patients and evaluated the additional value of the information from low-dose-computed tomography (CT).

MATERIALS AND METHODS

In this retrospective study, 54 patients who received ⁶⁸Ga-PSMA-PET/CT and ^99mTc-DPD-SPECT/CT within 80 days were extracted from our database. Osseous lesions were classified as benign, malignant or equivocal. Lesion, region and patient based analysis was performed with and without CT fusion. The reference standard was generated by defining a best valuable comparator (BVC) containing information from all available data.

RESULTS

In the patient based analysis, accuracies measured as "area-under-the-curve" (AUC) for ⁶⁸Ga-PSMA-PET, ^99mTc-SPECT, ⁶⁸Ga-PSMA-PET/CT and ^99mTc-SPECT/CT were 0.97-0.96, 0.86-0.83, 1.00 and 0.83, respectively (p<0.05) (ranges = optimistic vs. pessimistic view). Region based analysis resulted in the following sensitivities and specificities: 91.8-97.7%, 100-99.5% (PET); 61.2-70.6%, 99.8-98.3% (SPECT); 97.7%, 100% (PET/CT), 69.4% and 98.3% (SPECT/CT) (p<0.05). The amount of correct classifications of equivocal lesions by CT was significantly higher in PET (100%) compared to SPECT (52.4%) (p<0.05).

CONCLUSION

⁶⁸Ga-PSMA-PET outperforms ^99mTc-DPD-SPECT in detecting bone metastases in PC patients. Additional information from low-dose-CT resulted in a significant reduction in equivocal lesions in both modalities, however ⁶⁸Ga-PSMA-PET benefited most.

KEY POINTS

• Ga-PSMA-PET outperforms ^99m Tc-DPD-SPECT in skeletal staging in prostate cancer patients • Proportion of equivocal decisions was significantly reduced by CT-fusion in both modalities • Ga-PSMA-PET benefits more from CT information, compared to ^99m Tc-DPD-SPECT.

Spleen Uptake on a Bone Scan

We present a patient with spleen uptake on bone scanning that was due to sickle cell disease. We also discuss other etiologies for this finding.

Technetium-99m Methylene Diphosphonate Single-photon Emission Computed Tomography/Computed Tomography of the Foot and Ankle

The complex anatomy and function of the foot and ankle can make it difficult to determine the cause of symptoms in patients with foot and ankle pathology. Following initial clinical and radiographic assessment, additional imaging with magnetic resonance imaging may be required, which is often seen as the modality of choice. Although sensitive to pathological changes in bone metabolism and vascularity, technetium-99m (Tc-99m) bone scintigraphy often lacks the specificity and resolution required to evaluate the structures of the foot and ankle. Tc-99m methylene diphosphonate single-photon emission computed tomography/computed tomography (SPECT/CT) combines this sensitivity with the superior anatomical detail of CT, enabling better localization of pathological uptake and evaluation of associated structural changes. As a result, SPECT/CT has been growing in popularity for the assessment of patients with foot and ankle pathology where it can provide additional information that may change the initial diagnosis and subsequent management plan. Studies have reported modification of the surgical approach and site of intra-articular local anesthetic injections following SPECT/CT with good results. Interpretation of SPECT/CT studies requires an understanding of the pathological changes that result in increased tracer accumulation in addition to the CT changes that may be seen. This review aims to highlight the advantages of SPECT/CT, potential applications and explain the imaging appearances of common pathologies that may be observed.

Bone scintigraphy and panoramic radiography in deciding the extent of bone resection in benign jaw lesions

OBJECTIVE

To find out the value of correlating radiographic and scintigraphic imaging for defining the extent and nature of benign jaw lesions (BJL).

MATERIAL AND METHODS

Twenty patients with histologically proven benign lesions of the jaws were investigated pre-operatively by panoramic radiography (PR) and bone scintigraphy (BS). To test the efficacy of combination of these two imaging modalities, their results were compared with intra-operative and histopathological findings.

RESULT

Most of the benign lesions presented radiographically as well-defined bone destructions with fine sclerotic rims. Such lesions were found to be silent on scintigraphs and the extent of radionuclide uptake was same as radiographically visible extent of bone involvement. However, aggressive lesions showed ill-defined bone destructions without sclerotic rims on radiographs and their scintigraphic uptake correctly exceeded the radiographic extent of the bone involvement.

CONCLUSION

The efficacy of combination of both complementary imagings is rewarding in defining the extent of the BJL, especially when radiographic margins are not so well defined. So, that surgical excisions will be complete and the possibility recurrences is reduced.

Evaluation of bone viability

Bone scintigraphy is an excellent tool to assess bone viability. The functional information provided is crucial in several clinical settings, like the detection of avascular necrosis, septic embolism, frostbite lesions and osteonecrosis, and to evaluate the results of surgical treatment in cases of avascular necrosis. Mechanisms to obtain molecular images, as well as different kind of techniques, are detailed. Comparative and multimodality imaging to focus on any clinical problem and a review of the clinical indications reflect the multidisciplinary approach with close collaboration between orthopaedists, radiologists and nuclear medicine physicians. Finally, an effort has been made to list the most important points of imaging of bone viability in children.

The bone scan

Bone imaging continues to be the second greatest-volume nuclear imaging procedure, offering the advantage of total body examination, low cost, and high sensitivity. Its power rests in the physiological uptake and pathophysiologic behavior of 99m technetium (99m-Tc) diphosphonates. The diagnostic utility, sensitivity, specificity, and predictive value of 99m-Tc bone imaging for benign conditions and tumors was established when only planar imaging was available. Currently, nearly all bone scans are performed as a planar study (whole-body, 3-phase, or regional), with the radiologist often adding single-photon emission computed tomography (SPECT) imaging. Here we review many current indications for planar bone imaging, highlighting indications in which the planar data are often diagnostically sufficient, although diagnosis may be enhanced by SPECT. (18)F sodium fluoride positron emission tomography (PET) is also re-emerging as a bone agent, and had been considered interchangeable with 99m-Tc diphosphonates in the past. In addition to SPECT, new imaging modalities, including (18)F fluorodeoxyglucose, PET/CT, CT, magnetic resonance, and SPECT/CT, have been developed and can aid in evaluating benign and malignant bone disease. Because (18)F fluorodeoxyglucose is taken up by tumor cells and Tc diphosphonates are taken up in osteoblastic activity or osteoblastic healing reaction, both modalities are complementary. CT and magnetic resonance may supplement, but do not replace, bone imaging, which often detects pathology before anatomic changes are appreciated. We also stress the importance of dose reduction by reducing the dose of 99m-Tc diphosphonates and avoiding unnecessary CT acquisitions. In addition, we describe an approach to image interpretation that emphasizes communication with referring colleagues and correlation with appropriate history to significantly improve our impact on patient care.

Clinical molecular imaging with radiotracers: current status

Molecular imaging is defined as the visualization, characterization, and measurement of biological processes at the molecular and cellular levels in humans and other living systems. Most clinical molecular imaging is currently done using radioisotope-labeled agents to define the activity of various metabolic pathways in vivo or to determine the distribution and density of various receptors relevant to human disease. This paper briefly reviews most of the commonly used radiopharmaceuticals in nuclear medicine, as well as newer agents that are likely to become available in the near future. The metabolic pathways include those relevant to the thyroid, parathyroid, heart, brain, bones, kidneys, liver, pancreas, adrenals and tumor. The receptor systems include agents useful in evaluating movement disorders, dementia, cardiac sympathetic enervation and neoangiogenesis. Receptor systems relevant to tumors include somatostatin receptors (neuroendocrine tumors), prostate-specific membrane antigen, carbonic anhydrase IX (renal cancer), and CD-20 (lymphoma). These agents, and newer agents that are being developed, are likely to become critical in the development of personalized medicine, where it will become increasingly important to determine whether a treatment that is targeted to a specific metabolic pathway or receptor is likely to be successful.

Advances in drug design of radiometal-based imaging agents for bone disorders

Nuclear medicine bone imaging has been the optimum diagnosis for the detection of bone disorders because the lesion could be detectable before the appearance of symptomatic and radiographic changes. Over the past three decades, ^99mTc-MDP and ^99mTc-HMDP have been used as bone scintigraphic agents because of their superior biodistribution characteristics, although they are far from optimal from a chemical and pharmaceutical point of view. Recently, a more logical drug design has been proposed as a concept of bifunctional radiopharmaceuticals in which the carrier molecules (bisphosphonates) and radiometal chelating groups are separated within a molecule, specifically, ^99mTc-mononuclear complex-conjugated bisphosphonate. Some of the ^99mTc-mononuclear complex-conjugated bisphosphonate compounds showed superior biodistribution in preclinical studies. Moreover, the drug design concept could be applied to ⁶⁸Ga PET bone imaging agents. These studies would provide useful information for the development of radiometal-based imaging and therapeutic agents for bone disorders such as bone metastases.

Imaging of alkaline phosphatase activity in bone tissue

The purpose of this study was to develop a paradigm for quantitative molecular imaging of bone cell activity. We hypothesized the feasibility of non-invasive imaging of the osteoblast enzyme alkaline phosphatase (ALP) using a small imaging molecule in combination with ¹⁹Flourine magnetic resonance spectroscopic imaging (¹⁹FMRSI). 6, 8-difluoro-4-methylumbelliferyl phosphate (DiFMUP), a fluorinated ALP substrate that is activatable to a fluorescent hydrolysis product was utilized as a prototype small imaging molecule. The molecular structure of DiFMUP includes two Fluorine atoms adjacent to a phosphate group allowing it and its hydrolysis product to be distinguished using ¹⁹Fluorine magnetic resonance spectroscopy (¹⁹FMRS) and ¹⁹FMRSI. ALP-mediated hydrolysis of DiFMUP was tested on osteoblastic cells and bone tissue, using serial measurements of fluorescence activity. Extracellular activation of DiFMUP on ALP-positive mouse bone precursor cells was observed. Concurringly, DiFMUP was also activated on bone derived from rat tibia. Marked inhibition of the cell and tissue activation of DiFMUP was detected after the addition of the ALP inhibitor levamisole. ¹⁹FMRS and ¹⁹FMRSI were applied for the non-invasive measurement of DiFMUP hydrolysis. ¹⁹FMRS revealed a two-peak spectrum representing DiFMUP with an associated chemical shift for the hydrolysis product. Activation of DiFMUP by ALP yielded a characteristic pharmacokinetic profile, which was quantifiable using non-localized ¹⁹FMRS and enabled the development of a pharmacokinetic model of ALP activity. Application of ¹⁹FMRSI facilitated anatomically accurate, non-invasive imaging of ALP concentration and activity in rat bone. Thus, ¹⁹FMRSI represents a promising approach for the quantitative imaging of bone cell activity during bone formation with potential for both preclinical and clinical applications.

Osteomyelitis of the long bones

Long bone osteomyelitis presents a variety of challenges to the physician. The severity of the disease is staged depending upon the infection's particular features, including its etiology, pathogenesis, extent of bone involvement, duration, and host factors particular to the individual patient (infant, child, adult, or immunocompromised). Long bone osteomyelitis may be either hematogenous or caused by a contiguous spread of infection. A single pathogenic organism is almost always recovered from the bone in hematogenous osteomyelitis; Staphylococcus aureus is the most common organism isolated. A variety of multidrug-resistant organisms of bacteria continue to be a source of concern in arresting infection. The primary weapons to treat these infections are culture-specific antibiotics, aggressive debridement, muscle flaps, and bone grafts. This article offers a basic review of the classification, etiology, epidemiology, pathogenesis, and treatment of long bone osteomyelitis.

Bone marrow hypervascularity in patients with myelofibrosis identified by infra-red thermography

Infra-red thermography was used to assess bone marrow vascularity in six patients with myelofibrosis secondary to myeloproliferative disorders (four primary myelofibrosis and two primary proliferative polycythaemia). The technique was evaluated with conventional static and dynamic radio-isotopic imaging and with immunohistochemical staining of bone marrow biopsies. Infra-red thermography identified increased bone marrow blood flow in patients with established myelofibrosis and correlated with dynamic radio-isotopic studies of blood flow and hypervascularity identified by immunohistochemistry. Increased bone marrow blood flow and vascular proliferation was not confined to the central bone marrow but also extended into the peripheral marrow of the long bones. Endothelial cell proliferation may be an initiating event in the pathogenesis of myelofibrosis but evaluation of bone marrow vascularity and blood flow has hitherto relied on invasive and complicated techniques. This study has identified bone marrow hypervascularity in patients with myelofibrosis and shown infra-red thermography to be a simple non-invasive method of assessing vascularity. This non-invasive technique may be used to study disease progression and response to therapeutic regimens in patients with myelofibrosis and to study bone marrow blood flow in other bone marrow disorders.

Synthesis, characterization, and in vivo skeletal localization of a new 99mTc-based multidentate phosphonate chelate: 5-Amino-1,3-bis(ethylamine-(N,N dimethyl diphosphonic acid) acetamido) benzene

The tetraphosphonate ligand, 5-amino-1,3-bis(ethylamine-(N,N-dimethyl diphosphonic acid) acetamido) benzene (IPTMP) used in the present study was prepared from 5-nitroisophthalate dimethylester to label with radionuclide for targeted diagnosis and therapy. The synthesized multidentate phosphonate ligand was characterized on the basis of spectroscopic techniques, which exhibited good metal ion control properties when complexed to (99m)Tc with high in vitro and in vivo stability. Excellent quality bone images of rabbit were imaged showing rapid clearance of background activity and visualization of skeleton at 1h.

Adult osteomyelitis

Adult osteomyelitis remains difficult to treat, with considerable morbidity and costs to the health care system. Bacteria reach bone through the bloodstream, from a contiguous focus of infection, from penetrating trauma, or from operative intervention. Bone necrosis begins early, limiting the possibility of eradicating the pathogens, and leading to a chronic condition. Appropriate treatment includes culture-directed antibiotic therapy and operative debridement of all necrotic bone and soft tissue. Treatment often involves a combination of antibiotics. Operative treatment is often staged and includes debridement, dead space management, soft tissue coverage, restoration of blood supply, and stabilization. Clinicians and patients must share a clear understanding of the goals of treatment and the difficulties that may persist after the initial course of therapy or surgical intervention. Chronic pain and recurrence of infection still remain possible even when the acute symptoms of adult osteomyelitis have resolved.

Diffuse splenic tc-99m mdp uptake in hypersplenic patient

A 52-year-old woman with nonspecific left leg pain was examined by Tc-99m methylene diphosphonate (MDP) bone scintigraphy. The patient had been a marble quarry worker for 10 years and had developed chronic congestive heart failure secondary to pneumoconiosis. Her hemoglobin analysis and hematologic findings were interpreted as being consistent with sickle cell beta+ thalassemia and also hypersplenism. Bone scintigraphy showed intense and diffuse MDP accumulation in the enlarged spleen without ultrasonographic or radiologic evidence of calcification.

Osteomyelitis in long bones

Osteomyelitis in long bones remains challenging and expensive to treat, despite advances in antibiotics and new operative techniques. Plain radiographs still provide the best screening for acute and chronic osteomyelitis. Other imaging techniques may be used to determine diagnosis and aid in treatment decisions. The decision to use oral or parenteral antibiotics should be based on results regarding microorganism sensitivity, patient compliance, infectious disease consultation, and the surgeon's experience. A suppressive antibiotic regimen should be directed by the results of cultures. Standard operative treatment is not feasible for all patients because of the functional impairment caused by the disease, the reconstructive operations, and the metabolic consequences of an aggressive therapy regimen. Operative treatment includes debridement, obliteration of dead space, restoration of blood supply, adequate soft-tissue coverage, stabilization, and reconstruction.

Quantitative studies of bone with the use of 18F-fluoride and 99mTc-methylene diphosphonate

This article discusses methods for quantifying bone turnover based on tracer kinetic studies of the short-lived radiopharmaceuticals 99mTc-MDP and 18F-fluoride. Measurements of skeletal clearance obtained by using these tracers reflect the combined effects of skeletal blood flow and osteoblastic activity. The pharmacokinetics of each tracer is described, together with some of the quantitative tests of skeletal function that have been described in the literature. The physiologic interpretation of quantitative measurements of bone obtained with the use of short half-life radionuclides is discussed, and the advantages and limitations of 99mTc-MDP and 18F-fluoride are compared and contrasted. Currently, 18F-fluoride dynamic positron emission tomography (PET) is the technique of choice for physiologically precise quantitative studies of bone. However, comparable data could probably be obtained by using 99mTc-MDP if methods for single photon emission computed tomography (SPECT) quantitation were improved.

Radiolabeling with technetium-99m to study high-capacity and low-capacity biochemical systems

After a brief review of the history of the development of technetium-99m-labeled radiopharmaceuticals, the use of technetium chelates in high-capacity systems is discussed. The latter are used in the study of five organ systems, the kidneys, liver, bone, brain, and heart. The chemical characterization of 99mTc complexes is also reviewed, followed by discussion of the various approaches to the labeling of proteins with direct labeling, the preformed chelate approach, and the antibody chelator conjugate approach. Thereafter, the labeling of biochemicals with 99mTc for use with easily saturated sites, e.g., receptors and enzymes, is considered. Finally, attention is given to factors that affect the preparation of high specific activity, high affinity 99mTc-labeled biochemicals.

Technetium 99m-MDP scintigraphy of patients undergoing implant prosthetic procedures: a follow-up study

The clinical evaluation of peri-implant tissue is mainly based on x-rays. In recent years, radioisotope scintigraphy using Tc-99m-MDP (technetium-99m-methylene diphosphonate) proved to be a useful and reliable clinical method for measuring increased metabolic activity at specific sites of the skeletal tissue. Twenty-six (26) patients (26 to 75 years) who were diagnosed for implant prosthetic treatment modality were randomly chosen to participate in this study. Each patient was injected with 20 mCi of Tc-99m-MDP was scanned 2 hours later by gamma-camera for isotope uptake levels in the jaws. Each patient was scanned 1 to 4 times, starting 2 weeks after implant surgery and up to the 40th week postsurgery. Blade and screw type implants using the non-submerged, one-stage technique were placed. Therefore, the prosthetic reconstruction was initiated 2 weeks after implant surgery. In order to compare the different scans we formulated a relative "bone scan index" (BSI). The results of 62 scans were plotted as BSI against time after implant surgery. A mathematical regression analysis of the BSI was also performed. At the initial stage of 2 to 3 weeks after surgery the BSI is high and then gradually declines. While BSI of the implants in the mandible reaches baseline levels after 12 weeks, the BSI in the maxilla reaches baseline only after 20 weeks. On the other hand, there was no difference in BSI with regard to blade or screw type implant. Here we were able to demonstrate that the process is independent of implant modality and depends on the specific metabolic properties of the jaw.(ABSTRACT TRUNCATED AT 250 WORDS)

Retention of etidronate in human, dog, and rat

The retention of radioactivity in human, rat, and dog following a single injected dose of radiolabeled etidronate disodium (EHDP) is shown to follow power-law decay curves with similar slopes for times up to 4, 60, and 80 days, respectively. During this period retention declines with time according to a weak inverse power of the time since dosing, with an exponent ranging from -0.05 (dog) to -0.09 (human and rat). Direct analyses of dog bones either 90 days after a single dose or 365 days after cessation of chronic dosing indicate a more rapid bone clearance of EHDP than predicted by the initial power law. Direct skeletal analysis also shows a more rapid loss of radioactivity in the rat between 60 and 365 days, indicative of either a second power law or a terminal exponential phase in the retention function occurring after 60 days. These data are used to estimate the minimum and maximum amounts of drug that would remain in the body following long-term treatment in humans. For the intermittent cyclic EHDP treatment (ICT) regimen for osteoporosis (repeated cycles of 14 daily doses of 400 mg orally followed by 76 days drug free), the projected retention of EHDP after 3 years of treatment is 25-50 times the daily absorbed dose. Thus, for a 60 kg woman with a daily absorbed dose of 12 mg, the retained mass of EHDP would be about 300-600 mg.(ABSTRACT TRUNCATED AT 250 WORDS)

Tc-99m-HMDP bone uptake quantification and plasma osteocalcin levels in hemodialysis patients--a preliminary study

In this preliminary study plasma osteocalcin levels and Tc-99m-HMDP (Technetium 99m hydroxymetylene diphosphonate) bone uptake (BU) were measured in 10 chronic end-stage renal failure patients who were on maintenance hemodialysis. The aim of this study was to determine the correlation between bone uptake and osteocalcin-a sensitive and specific marker of osteoblastic activity. There was a statistically significant increase in both 20 and 180 minute uptake in the patient group (36 +/- 2.7 and 39 +/- 3.6) when compared to the normal volunteers (32 +/- 3.1 and 19 +/- 2.7). Plasma osteocalcin levels were also significantly high (24.5 +/- 5.6 ng/ml) when compared with normal values (6.5 +/- 2.3 ng/ml). The correlations between osteocalcin and 20 and 180 min BU were high (r = 0.62 and 0.72 respectively). In conclusion, our preliminary study suggests that, in hemodialysis patients, Tc-99m-HMDP bone uptake quantification is a sensitive and non-invasive method for showing increased osteoblastic activity.

Case report: intravenous etidronate as a cause of poor uptake on bone scanning, with a review of the literature

Bone scanning is the most frequent type of radionuclide examination performed. We present a case of reduced uptake on a bone scan thought to be due to etidronate therapy. Other causes of this phenomenon are reviewed.

Use of digital radiography to demonstrate the potential of naproxen as an adjunct in the treatment of rapidly progressive periodontitis

The effect of the non-steroidal anti-inflammatory drug, naproxen, in reducing periodontal disease activity was assessed in 15 patients with rapidly progressive periodontitis. All patients in this double-blind study were treated with scaling and root planing. Thereafter, 7 patients receiving 500 mg naproxen b.i.d. for 3 months, and 8 patients received placebo. Disease activity was assessed in three ways. First, alveolar bone height was determined using standardized radiography. Second, alterations in alveolar bone metabolism were assessed using 99m-Tc-methylene diphosphonate uptake prior to dosing and 3 months later. Finally, bone loss or gain was detected using digital subtraction radiography. In this study, conventional subtraction images were processed to isolate the area of change and superimpose the change on the original radiograph. This allowed determination of both the direction and location of osseous changes. There was significantly less bone loss as determined by analysis of bone height during the 3-month study in the naproxen-treated patients when compared to the placebo-treated patients (p less than 0.001). Radiopharmaceutical uptake was significantly reduced in the alveolar bone in patients receiving naproxen (p less than 0.03), whereas no significant change was observed in the placebo-treated patients. Furthermore, the subtraction radiographs showed a significant increase in the proportion of teeth demonstrating bone gain in the naproxen-treated group. These findings indicate that naproxen may be a useful adjunct to scaling and root planing in patients with rapidly progressive periodontitis.

Detection of periodontal disease activity with a scintillation camera

The goal of this study was to assess the ability of a scintillation camera method to detect areas of active bone loss due to periodontitis. Technetium 99m methylene diphosphonate was used as the bone-seeking radiopharmaceutical. Bone-seeking radiopharmaceutical uptake (BSRU) was imaged and quantified in alveolar bone regions of interest with a scintillation camera and a computer. Analysis of the sequential radiographs over six months constituted the basis for determination of sites of active disease. The study was composed of two parts. First, 18 subjects, nine with adult periodontitis and nine controls, were enrolled in a cross-sectional study to determine whether the quantitative scintillation amera methodology detected differences in BSRU in periodontitis vs. periodontally healthy patients. Second, the nine patients with periodontitis were studied longitudinally in order to determine whether the BSRU examination was indicative of bone loss subsequently measured radiographically. In the cross-sectional study, the mean uptake ratio for the periodontitis group was significantly higher than that for the control group (1.63 +/- 0.06 and 1.42 +/- 0.04, respectively, p less than 0.01, t test). From the longitudinal study, the mean patient scintillation image uptake ratios were highly correlated with the mean bone loss determined from serial radiographs (p less than 0.01). The accuracy, sensitivity, and specificity of the quantitative gamma camera method for detecting site(s) of active bone loss within the region of interest were assessed relative to the longitudinal radiographic data. The accuracy, sensitivity, and specificity were 85%, 90%, and 79%, respectively. Alveolar bone scintigraphy with a gamma camera and computer may provide a simple and valid technique for the immediate indication of areas of periodontal disease activity.

Phosphonato complexes of platinum(II): kinetics of formation and phosphorus-31 NMR characterization studies

Reactions of cis-diamminedichloroplatinum(II) with phosphonoformic acid (PFA), phosphonoacetic acid (PAA), and methylenediphosphonic acid (MDP) yield various phosphonatoplatinum(II) chelates which were characterized by phosphorus-31 NMR spectroscopy. The P-31 resonances for the chelates appear at 6-12 ppm downfield as compared to the uncomplexed ligands. All complexes exhibit monoprotic acidic behavior in the pH range 2-10. The chemical shift-pH profiles yielded acidity constants, 1.0 x 10(-4), 1.5 x 10(-4), and 1.3 x 10(-6) M-1, for the PFA, PAA, and MDP chelates. In addition to the monomeric chelate, MDP formed a bridged diplatinum(II,II) complex when it reacted with cis-Pt (NH3)2(H2O)2(2)+. The P-31 resonance for this binuclear complex appears at 22 ppm downfield from the unreacted ligand. Rate data for the complexation reactions of the phosphonate ligands with the dichloroplatinum complex are consistent with a mechanism in which a monodentate complex is formed initially through rate-limiting aquation process of the platinum complex, followed by a rapid chelation. For the PFA and PAA complexes, initial binding sites are the carboxylato oxygens. Implications of the various binding modes of the phosphonates in relationship to their antiviral activities are discussed.

Comparison of technetium 99m-phytate and technetium 99m-sulphur colloid in primary bone tumours

Eleven patients with proven primary bone tumour (five Ewing sarcomas, six osteosarcomas) and two cases of metastatic bone involvement (primary other than bone) were investigated with 99mTc-phytate and 99mTc-sulphur colloid to compare the behaviour of the two radiopharmaceuticals at the tumour site. After intravenous administration of the respective radiopharmaceutical, imaging of the tumour site and its contralateral part was carried out at 15 min and 1 h intervals. The data were stored in our computer. Bone scanning was also carried out in all patients. 99mTc-phytate uptake was observed at the tumour site in ten cases. The 99mTc-sulphur colloid study revealed sparse or no significant uptake in eight cases. In two patients, with osteosarcoma 99mTc-sulphur colloid investigation showed uptake at the primary tumour site. However, the distribution pattern is different from that of 99mTc-phytate. No significant uptake of either 99mTc-phytate or 99mTc-sulphur colloid was observed in the two patients with metastatic skeletal disease. It may be concluded that the unusual accumulation of 99mTc-phytate at the tumour site is not due to any generalized reticuloendothelial phenomenon and that the radiopharmaceutical itself is responsible for this.

Accumulation of technetium-99m MDP in pseudomyxoma peritonei

An ovarian mucinous cystadenocarcinoma which moderately accumulated Tc-99m MDP was imaged during a whole body bone scan. The primary tumor and its implants in the peritoneal cavity were both visualized and correlated with US and TCT scan findings. As a result, the radiopharmaceutical distribution accurately delineated the primary tumor and the region of tumor involvement within the peritoneal cavity. Therefore, a whole body bone scan offers a potential method for assessing neoplastic size and spread.

A contemporary perspective on techniques for the clinical assessment of alveolar bone

Radiographic techniques, traditional ones as well as newer ones under development, for clinically assessing alveolar bone are critically assessed. Traditional intraoral radiography is reexamined, in particular with regard to the accuracy with which the alveolar crest is seen. Evidence is presented for a more accurate representation of the alveolar crest on bitewings rather than periapical films. Application in periodontics of newer radiographic techniques, subtraction radiography, and single and dual photon aborptiometry presently under clinical development are discussed in regard to their potential and limitations. Similarly, radiopharmaceuticals to evaluate the metabolic status of alveolar bone are discussed as well as the potential for using analyses of gingival crevice fluid as a window for assessment of alveolar crest metabolism.

Local anesthetics and nuclear medical bone images of the equine fore limb

The effects of two local anesthetic agents on the diagnostic quality of nuclear medical bone images (NMBIs) of distal parts of the equine fore limb were investigated. Local effects on bone uptake of technetium 99m methylene diphosphonate (99mTc-MDP) 4 and 24 hours after perineural and intraarticular injection of mepivacaine hydrochloride and bupivacaine hydrochloride were evaluated in the carpal and metacarpophalangeal regions of 12 horses and ponies. Neither mepivacaine hydrochloride nor bupivacaine hydrochloride significantly altered the diagnostic quality of the NMBIs. The injection and subsequent action of local anesthetics do not appear to influence local bone uptake of 99mTc-MDP significantly.

Malignant external otitis in children

Malignant external otitis in the pediatric population is primarily a disease of children with chronic illness or immunosuppression. The presence of severe, unrelenting otalgia, otorrhea with isolation of Pseudomonas aeruginosa, a markedly elevated erythrocyte sedimentation rate, and evidence of bone destruction on computed tomography scan should alert the clinician to the diagnosis. Unlike adults, children have a higher incidence of seventh nerve paralysis earlier in the course of the infection. They also manifest more frequent involvement of the middle ear with tympanic membrane destruction. The short interval between the onset of symptoms and facial nerve dysfunction highlights the necessity of prompt diagnosis and institution of anti-Pseudomonas therapy. Our review suggests that this destructive bacterial infection is an emerging clinical entity in children; 73% of the cases have been reported since 1980. Pediatricians should therefore be familiar with the clinical presentation of this treatable infection. Substantial morbidity could be alleviated by prompt diagnosis and early antibiotic treatment.

Malignant external otitis: insights into pathogenesis, clinical manifestations, diagnosis, and therapy

Malignant external otitis is an infection of the external ear canal, mastoid, and base of the skull caused by Pseudomonas aeruginosa. The condition occurs primarily in elderly patients with diabetes mellitus. Current theories on pathogenesis and anatomic correlations are reviewed. Severe, unrelenting otalgia and persistent otorrhea are the symptomatic hallmarks of the disease, whereas an elevated erythrocyte sedimentation rate is the only distinctive laboratory abnormality. Iatrogenic causes such as administration of broad-spectrum antibiotics and aural irrigation may play a predisposing role in high-risk populations. The disease can result in cranial polyneuropathies (with facial nerve [VII] paralysis being the most common) and death. The mainstay of treatment is administration of antipseudomonal antibiotics for four to eight weeks. Recurrence is common, and mortality remains at about 20 percent despite antibiotic therapy. Given the increasing longevity of diabetic patients, the frequency of this disease is increasing. Internists, family practitioners, and ambulatory care physicians must now be cognizant of the presenting symptoms, while infectious disease specialists and otolaryngologists need to be appraised of strides in diagnosis and therapy. The role of surgery should be minimized. Use of new diagnostic radiologic modalities and new antipseudomonal antibiotics discussed in this review should lead to improved outcome.