Diagnosis of osteomyelitis in children by combined blood pool and bone imaging

ACR Appropriateness Criteria® Osteomyelitis or Septic Arthritis-Child (Excluding Axial Skeleton)

Imaging plays an integral role in the evaluation of suspected musculoskeletal infections in children, not only in the accurate identification of infection such as osteomyelitis or septic arthritis, but also in guiding management. Various diagnostic modalities serve different purposes in the assessment of suspected pediatric musculoskeletal infections. The purpose of this document is to provide imaging guidance in the most frequently encountered clinical scenarios in which osteomyelitis and/or septic arthritis are suspected, outside of the axial skeleton. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion.

A systematic review showing the lack of diagnostic criteria and tools developed for lower-limb cellulitis

Background

Cellulitis can be a difficult diagnosis to make. Furthermore, 31% of patients admitted from the emergency department with suspected lower‐limb cellulitis have been misdiagnosed, with incorrect treatment potentially resulting in avoidable hospital admission and the prescription of unnecessary antibiotics.

Objectives

We sought to identify diagnostic criteria or tools that have been developed for lower‐limb cellulitis.

Methods

We conducted a systematic review using Ovid MEDLINE and Embase databases in May 2018, with the aim of describing diagnostic criteria and tools developed for lower‐limb cellulitis, and we assessed the quality of the studies identified using the Quality Assessment of Diagnostic Accuracy Studies‐2 tool. We included all types of study that described diagnostic criteria or tools.

Results

Eight observational studies were included. Five studies examined biochemical markers, two studies assessed imaging and one study developed a diagnostic decision model. All eight studies were considered to have a high risk for bias in at least one domain. The quantity and quality of available data was low and results could not be pooled owing to the heterogeneity of the findings.

Conclusions

There is a lack of high‐quality publications describing criteria or tools for diagnosing lower‐limb cellulitis. Future studies using prospective designs, validated in both primary and secondary care settings, are needed.

What's already known about this topic?

Diagnosing lower‐limb cellulitis on first presentation is challenging.

Approximately one in three patients admitted from the emergency department with suspected lower‐limb cellulitis do not have cellulitis and are given another diagnosis on discharge. Consequently, this results in potentially avoidable hospital admissions and the prescription of unnecessary antibiotics.

There are no diagnostic criteria available for lower‐limb cellulitis in the U.K.

What does this study add?

This systematic review has identified a key research gap in the diagnosis of lower‐limb cellulitis.

There is a current lack of robustly developed and validated diagnostic criteria or tools for use in clinical practice.

Linked Comment: https://doi.org/10.1111/bjd.18317.

https://doi.org/10.1111/bjd.18569 available online

Nuclear Medicine Imaging in Pediatric Infection or Chronic Inflammatory Diseases

In this review article, we focus on the most recent applications of nuclear medicine techniques (mainly ^99mTc/¹¹¹In white blood cells (WBC) scan, [¹⁸F]-FDG-PET/CT, [¹⁸F]-FDG-PET/MRI, and ^99mTc-IL-2 scintigraphy) in the study of children affected by peripheral bone osteomyelitis, fungal infections, inflammatory bowel diseases, and type 1 diabetes, owing to recent important published evidences of their role in the management of these diseases. For osteomyelitis in children, both bone scintigraphy and [¹⁸F]-FDG-PET have a major advantage of assessing the whole body in one imaging session to confirm or exclude multifocal involvement, whereas WBC scan has a limited role. In children with fungal infections, [¹⁸F]-FDG-PET can help in defining the best location for biopsy and can help in evaluating the extent of the infection and organs involved (also sites that were not yet clinically apparent), although its main role is for therapy monitoring. In inflammatory bowel diseases, and Crohn disease in particular, WBC scan has been successfully used for many years, but it is now used only in case of doubtful magnetic resonance (MR) or when MR cannot be performed and endoscopy is inconclusive. By contrast, there is an accumulating evidence of the role of [¹⁸F]-FDG-PET in management of children with Crohn disease, and PET/MR could be a versatile and innovative hybrid imaging technique that combines the metabolic information of PET with the high soft tissue resolution of MR, particularly for distinguishing fibrotic from active strictures. Finally, there are several new radiopharmaceuticals that specifically target inflammatory cells involved in the pathogenesis of insulitis aiming at developing new specific immunotherapies and to select children candidates to these treatments for improving their quality of life.

Three phase bone scan interpretation based upon vascular endothelial response

Objectives:

A new method of interpretation of Three Phase Bone Scan (TPBS) scan based upon the normal physiological vascular endothelial related response.

Materials and Methods:

Fifty cases of TPBS were evaluated. Thirteen were normal. In remaining 37 positive studies, 20 showed localized hyperemic response. All localized hyperemic responses except one with vascular endothelial dysfunction were without infection (95.0%). Infection could be ruled out in absence of generalized massive flow and pool response. All 17 cases with generalized massive hyperemic response had infection, consistent with infection or CRPS/RSD. Micro-bacterial or histological confirmation of infection was obtained in 11 cases. All 11 cases with confirmed infection showed generalized massive hyperemic response (100.0%). Two were CRPS/RSD and 2 cases were of cellulitis (100.0%). Among remaining 2, one refused surgery and other was lost to follow-up. Additionally, 20 published cases in the literature of osteomyelitis were also analyzed. Nineteen cases of bone and joint infection, (osteomyelitis/arthritis/cellulitis) except one with endothelial dysfunction showed generalized massive increased flow and pool response (95.0%). All published cases of osteomyelitis in the literature showed generalized massive hyperemic response (100.0%).

Results:

The data clearly indicated that 100% of the cases of bone infection (osteomyelitis/arthritis/cellulitis) and cases of CRPS/RSD showed generalized massive flow and pool pattern. Infection could be ruled out in absence of generalized massive flow and pool response. All 100% published cases of osteomyelitis in the literature showed positive vascular endothelial response.

Conclusion:

By incorporating the concept of vascular endothelial related response causing massive vasodilatation in infection, the interpretation of the TPBS can be more précised as it is based upon the normal physiology. Larger studies are recommended.

Pediatric osteomyelitis: a scintigraphic case-based review

This review presents techniques to optimize bone scintigraphy for evaluation of the spectrum of abnormalities associated with pediatric osteomyelitis, with an emphasis on the approaches to patient preparation and positioning and to interpretation. The diagnosis of pediatric osteomyelitis can be challenging for several different reasons. Bone scintigraphy is especially useful when the site of osteomyelitis is unclear. Other imaging modalities, including radiography, ultrasonography, and magnetic resonance imaging, all have advantages and may have a role in evaluating the condition of the child with osteomyelitis. Pathophysiologic considerations unique to children contribute to a different clinical presentation of osteomyelitis in the pediatric population than that seen in adults. In addition, patient movement degrades image quality substantially, which is an important consideration for imaging children. Neonates have a higher incidence of multifocal osteomyelitis, and they represent a unique subset of the pediatric population with separate considerations. Several examples illustrate techniques to optimize imaging, as well as show the spectrum of abnormalities associated with pediatric osteomyelitis. Careful attention to bone scintigraphic technique ensures that high-quality images can be obtained, which will allow confident diagnosis of pediatric osteomyelitis.

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.

Tc99m MDP bone SPECT in a case of osteomyelitis of the skull

A seven-year-old male child presented with swelling at the left temporal region. His skull X-ray was normal. A three-phase bone scan showed increased blood flow, soft tissue activity, and increased tracer concentration in the left temporal region. Single photon emission computed tomography (SPECT) imaging of the skull revealed full thickness involvement of the left temporal bone. Our case report shows that, in osteomyelitis of the skull, SPECT imaging provides significantly more information for identifying the extent and thickness of bone involvement.

MRI for Detection of Abscess in Acute Osteomyelitis of the Pelvis in Children

OBJECTIVE

We analyzed our experience with MRI of pelvic acute hematogenous osteomyelitis (AHO) to address the following questions: What does MRI reveal about bone involvement? How often are fluid collections indicative of abscess shown? Are clinical parameters predictive of the cases in which MRI would be more beneficial?

MATERIALS AND METHODS

We retrospectively reviewed the imaging studies and medical records from the past 5 years of 38 children ranging in age from 25 to 211 months who were diagnosed with pelvic osteomyelitis using MRI. Statistical analysis of demographic and clinical variables was compared between patients with an abscess (n = 21) and those without (n = 17) who were identified on MRI.

RESULTS

Osteomyelitis involved metaphyseal equivalent sites in every case (n = 38), with single bone involvement in 24 (63%) and contiguous bone involvement in the remaining 14 (37%). Fluid collections indicative of an abscess were seen in 21 cases (55%), and abscess drainage was performed in 10 (26%). Univariate analysis of demographic and clinical variables between patients with and without an abscess indicated no significant differences for any variable except erythrocyte sedimentation rate (ESR) (74 +/- 19 vs 56 +/- 24 mm/h; p< 0.05, Student's t test).

CONCLUSION

Childhood pelvic AHO is relatively uncommon and produces variable signs and symptoms that are often attributed to another process. The results of our study show the ability of MRI to provide additional information that affected patient management in cases of pelvic abscess. We therefore advocate the use of MRI as the imaging technique of choice for any child suspected of having pelvic AHO.

Bone scintigraphy in the investigation of occult lameness in the dog

99mTechnetium methylene diphosphonate (99mTc-MDP) scintigraphy was performed in 14 dogs of different breeds after clinical lameness examination, radiography and synovial fluid analysis failed to localise lameness to a specific area of pain. The scintigraphic protocol included an intravenous injection of 17 MBq 99mTc-MDP/kg bodyweight and vascular, soft tissue and bone phase scans in standardised positions with a low-energy all-purpose collimator. Confirmation of diagnosis was achieved in nine dogs by arthroscopy, repeated lesion-orientated radiography, computed tomography and response to treatment. In seven cases, bone phase scans showed single elbow uptakes, in two cases unilateral limb uptake, and in one case each a single shoulder and tibia uptake; in three cases there was no increased uptake. Vascular and soft tissue phase images did not reveal additional information. Diagnosis of humeral condyle fissures, a fragmented medial coronoid process, panosteitis and arthropathy was possible in nine cases. Skeletal pathology was ruled out in three normal scintigrams. In two dogs with unilateral uptake of multiple joints, no diagnostic benefit was gained from scintigraphy. The highly sensitive and relatively specific uptake allowed localisation and characterisation or exclusion of skeletal lesions in most dogs.

Skeletal scintigraphy in the multimodality assessment of young children with acute skeletal symptoms

The authors review the scintigraphic manifestations of acute osteomyelitis, septic arthritis, transient synovitis, Legg-Calvé-Perthes disease, fractures of toddlers, and some systemic conditions that cause skeletal symptoms during childhood. They offer suggestions regarding incorporation of skeletal scintigraphy into a multimodality approach for assessing children with skeletal symptoms.

Use of scintigraphy for assessment of fracture healing and early diagnosis of osteomyelitis following fracture repair in rabbits

OBJECTIVE

To evaluate use of technetium Tc 99m disodium hydroxymethylene diphosphonate (99m-Tc-HDP) for assessing fracture healing and 99m-Tc-HDP and technetium Tc 99m ciprofloxacin (99m-Tc-CIPRO) for early diagnosis of osteomyelitis in rabbits.

ANIMALS

32 skeletally mature New Zealand White rabbits.

PROCEDURE

A femoral fracture defect stabilized with bone plates and cortical screws was used. Scintigraphy was performed 4, 8, 12, and 16 weeks after surgery. The 99m-Tc-CIPRO scan was performed 48 hours after the 99m-Tc-HDP scan. The uptake ratio of the experimental limb to the normal limb was calculated by use of multiple regions of interest. Results of radiography performed to determine external callus and lysis grade and percentage defect ossification at 16 weeks were compared with scintigraphy results.

RESULTS

Infected fractures had a higher uptake ratio for 99m-Tc-HDP and 99m-Tc-CIPRO than noninfected fractures. Infected fractures could be differentiated from noninfected fractures late in healing by use of 99m-Tc-HDP. Although 99m-Tc-CIPRO was better than 99m-Tc-HDP for identifying infection, there was a high incidence of false positive and negative results with 99m-Tc-CIPRO. There was an association between 99m-Tc-HDP uptake ratio and callus formation and a good correlation between 99m-Tc-HDP uptake ratio and defect ossification after 4 weeks.

CONCLUSIONS AND CLINICAL RELEVANCE

99m-Tc-HDP and 99m-Tc-CIPRO may be useful for diagnosing osteomyelitis late in fracture healing; however, false positive and false negative results occur. Technetium Tc 99m disodium hydroxymethylene diphosphonate may be useful for evaluating fracture healing.

Nuclear medicine topics in pediatric musculoskeletal disease: techniques and applications

Musculoskeletal scintigraphy has excellent sensitivity for the evaluation of benign disease in children. Using illustrative cases, a spectrum of techniques and applications of nuclear medicine studies for benign bone diseases are presented. An approach to the use and evaluation of bone density evaluation in children also is discussed.

Dynamic radioisotope bone imaging as a noninvasive indicator of canine tibial blood flow

The relative values of dynamic and static bone imaging with hydroxymethylenediphosphonate technetium 99m (99mTc HDP) as an indicator of bone blood flow was investigated in the tibia of mature dogs. The dynamic bone scan consisted of 60 1-s images formed after the intravenous injection of 99mTc HDP, and the static bone scan was a 45-min uptake image. Blood flow to the tibia was determined by using radioactively labeled microspheres. Studies were carried out in control dogs, in dogs in which blood flow was increased in one leg with ATP, and in dogs in which blood flow was decreased in one leg with norepinephrine. A significant (p less than 0.001) linear relationship between the dynamic scan values and bone blood flow was found at a wide range of blood flow rates. When blood flow increased by more than 50%, the effects of "diffusion limitation" were seen in the static scans: increase in tracer uptake was disproportionately small for a significant increase in blood flow. There is no method currently available for estimating bone blood flow by a noninvasive technique. The method described here may be useful for providing a semiquantitative measure of bone blood flow. This improved versatility of bone imaging may have a role in the management of osteomyelitis or complicated fractures, or in assessing the viability of vascularized bone grafts.

Role of scintigraphy in musculoskeletal and spinal infections

Clinical findings are still the mainstay for suspecting the diagnosis of musculoskeletal infections, especially osteomyelitis. No single complementary imaging technique has 100% specificity and sensitivity for every case of musculoskeletal infection. Depending on the age of the patient, presence of orthopedic hardware, location of infection, underlying bone, and systemic conditions, the choice of imaging modalities must be tailored to the patient's condition. Plain radiographs are performed first and may be sufficient. In children, bone scan is highly accurate to diagnose osteomyelitis. Labeled leukocytes with complementary bone or bone marrow studies are recommended for orthopedic hardware or diabetic foot. Finally, gallium scanning is useful for the diagnosis of vertebral osteomyelitis. Current radiopharmaceuticals used for diagnosing infection also label inflammation. Newer products, as Infecton, should in the future allow better differentiation between infection and sterile inflammation.

Bacterial osteomyelitis in adults: evolving considerations in diagnosis and treatment

Bacterial osteomyelitis causes substantial morbidity worldwide, despite continued progress toward understanding its pathophysiology and optimal management. The approach to osteomyelitis depends upon the route by which bacteria gained access to bone, bacterial virulence, local and systemic host immune factors, and patient age. While imaging studies and nonspecific blood tests may suggest the diagnosis, an invasive technique is generally required to identify the causative pathogens. Given the paucity of comparative clinical trials, antibacterial regimen selection has been largely guided by knowledge of the relative activities and pharmacokinetics of individual drugs, supported by data from animal models. Definitive therapy often requires a combined medical and surgical approach. Newer microvascular and distraction osteogenesis techniques and the use of laser doppler allow more complete surgical resection of infected material while maintaining function. Despite recent advances, many patients with osteomyelitis fail aggressive medical and surgical therapy. More accurate diagnostic methods, better ways to assess and monitor the effectiveness of therapy, and novel approaches to eradicate sequestered bacteria are needed.

Three-phase skeletal scintigraphy in gouty arthritis: an example of potential diagnostic pitfalls in radiopharmaceutical imaging of the extremities for infection

The three-phase bone scan has been shown to be useful in the diagnosis of osteomyelitis, with a high sensitivity and specificity under optimal conditions. However, there are many causes of focally-increased uptake of Tc-99m diphosphonates in the extremities that may mimic infection, especially when there is increase on all three phases. Radiolabeled leukocyte scintigraphy is often performed in this clinical setting, although many pitfalls resulting in false-positive scans still remain. The authors present three cases of gouty arthritis in which skeletal scintigraphy illustrates this lack of specificity. Further causes of increased extremity uptake are reviewed, with attention to those that have been reported to show an increase on all three phases of the bone scan. Additional factors that can improve the specificity of the bone scan are discussed, as are the panoply of more recent scintigraphic approaches aimed at distinguishing infection from aseptic inflammation in the extremity. Unfortunately, no nuclear medicine procedure to date has proven itself to be reliably specific for infection.

Where are we with nuclear medicine in pediatrics?

The practice of nuclear medicine in children is different from that in adults. Technical considerations including immobilization, dosing of radiopharmaceuticals, and instrumentation are of major importance. Image magnification and the capability to perform single-photon emission tomography are essential to performing state of the art pediatric nuclear medicine. New advances in instrumentation with multiple detector imaging, the possibility of clinical positron emission tomography imaging in children, and new radiopharmaceuticals will further enhance pediatric scintigraphic imaging. This review highlights advances in pediatric nuclear medicine and discusses selected clinical problems.

Acute haematogenous osteomyelitis--evaluation of management in the 1990s

There are three main areas of debate in the management of acute haematogenous osteomyelitis: The value of early operative intervention, the duration and route of antibiotic treatment and the choice of antibiotic therapy. The aim of this study is to evaluate the management protocol of acute haematogenous osteomyelitis as used in The Childrens' Hospital, Temple Street. The protocol can be recommended. Absence of pyrexia and a normal Erythrocyte Sedimentation Rate do not exclude acute haematogenous osteomyelitis. Current thoughts on antimicrobial therapy are presented.

Multimodality imaging of osteomyelitis

Early diagnosis of osteomyelitis continues to be a clinical problem. Multiple imaging modalities are being used for the diagnosis of osteomyelitis, but none of them is ideal for all cases. The choice of modality depends on several factors based on an understanding of the pathophysiologic aspects of different forms of osteomyelitis. After a brief introduction outlining some basic principles regarding the diagnosis of osteomyelitis, pathophysiologic aspects are reviewed. Advantages and disadvantages of each imaging modality and their applications in different forms of osteomyelitis are discussed. The use of different imaging modalities in the diagnosis of special forms of osteomyelitis, including chronic, diabetic foot, and vertebral osteomyelitis, and osteomyelitis associated with orthopedic appliances and sickle cell disease is reviewed. Taking into account the site of suspected osteomyelitis and the presence or absence of underlying pathologic changes and their nature, an algorithm summarizing the use of various imaging modalities in the diagnosis of osteomyelitis is presented.

Diagnostic value of bone scintigraphy in osteomyelitis of the mandible

Thirty-five patients each with a tentative diagnosis of osteomyelitis of the mandible were examined with 99Tcm-labeled phosphorus compounds. The scintigraphic findings were compared with the radiographic features and related to disease stages to evaluate the diagnostic potential of bone scintigraphy in different disease stages. The scintigraphy was valuable to exclude bone tissue involvement in some patients with clinical signs and symptoms similar to those of osteomyelitis and with equivocal radiographic findings. In 13 patients with chronic osteomyelitis, scintigraphy revealed a larger extent of the lesion than the radiography. In lesions with permeated bone destructions with penetration of the cortex, the uptake of 99Tcm was higher than in lesions with a motheaten or sclerotic appearance. This study supports the view that 99Tcm-bone scintigraphy is a useful tool at various stages of osteomyelitis, that is, in its early detection, in the treatment or biopsy planning, and in the evaluation of the efficacy of treatment.

Initial stage of Legg-Calve-Perthes disease: comparison of three-phase bone scintigraphy and SPECT with MR imaging

Twenty-one patients with initial stage Legg-Calve-Perthes (LCP) disease were examined by three-phase bone scintigraphy, single photon emission scintigraphy (SPECT), and magnetic resonance (MR) imaging. On dynamic study, increased activity was present in the epiphysis or the growth plate in 39%; the corresponding figure for blood-pool images was 94%. Pinhole images demonstrated the lateral stripe of revascularization in 57% of patients. Decreased signal intensity in the epiphysis on T1-weighted images proved to be the most sensitive indicator of epiphyseal necrosis on MR imaging and was absent in only 10% of the cases. The subchondral fracture occurred in 62% (including the above 10% of cases), identified by T1-weighted image. Cartilaginous hypertrophy, detected by T1-weighted image, had a high incidence (81%). Joint effusion was identified on T2-weighted images in 90% of patients. The cross-sectional views provided by SPECT and MR imaging permits a better appreciation of the extent of epiphyseal necrosis in LCP disease.

Treatment of chronic traumatic bone wounds. Microvascular free tissue transfer: a 13-year experience in 96 patients

During a 13-year period at the Massachusetts General Hospital, Boston, Massachusetts, 97 microvascular free tissue transfers have been performed for soft-tissue reconstruction in 96 patients following bone debridement for chronic traumatic bone wounds. These 96 patients comprise a continuation study of 18 original patients reported in 1982. During a 13-year follow-up period (mean, 77.1 months), 95.8% of these 96 patients have enjoyed complete wound closure with a lack of drainage after the debridement and free tissue transfer. Most of the patients (89.6%) encountered in this study are ambulatory without assist and 5.2% of patients have undergone amputation. Twenty-three per cent of patients required subsequent segmental bone defect reconstruction in the lower extremity after infection eradication. The pathophysiology of chronic traumatic bony wounds is different from that of chronic hematogenous osteomyelitis and thus a high incidence of long-term successful management can be seen through complete wound debridement and adequate soft-tissue coverage.

Dynamic bone imaging in the investigation of local bone pathology--when is it useful?

The aim of this work was to establish when, in the investigation of local musculoskeletal symptoms, dynamic isotope bone imaging yields useful information not available from static isotope bone imaging, using 99mTc methylene diphosphonate. One hundred and forty-two dynamic bone scans were reviewed, with particular reference to the site being imaged, the suspected underlying pathology, and the contribution of the dynamic phases to diagnosis, management, and eventual outcome. All were performed as part of the investigation of adult patients complaining of localized musculoskeletal symptoms. The dynamic phases influenced diagnosis, management, and eventual outcome most positively in suspected infection, particularly at a previous fracture site or around a prosthesis. They did not alter management significantly in suspected fracture, avascular necrosis, in most patients with pain of unknown cause, and were rarely helpful in imaging the axial skeleton. We suggest that, in the context of routine bone imaging, dynamic bone scanning should be reserved for cases of suspected infection. In the investigation of most other local bone pathologies, the static phase of the bone scan provides all the diagnostic information which is required for management decisions.

Dynamic bone imaging in the differential diagnosis of skeletal lesions

Dynamic bone imaging differs from routine multiphase bone scintigraphy by the use of time-activity curves (TACs) and quantitation of data. TACs were divided into an arterial plus blood pool phase (first 60 s at 1 frame/s) and a subsequent early bone uptake phase (24 min at 1 frame/min). Ratios of normalized integrals, from analogous regions were calculated to determine whether blood flow was abnormal. A key feature of the technique is the monitoring of the flow proximally and distally to the area of involvement. This was of importance in distinguishing between two diseases producing the same degree of local hyperemia. Dynamic bone imaging was applied to the differential diagnosis of arthritis, septic arthritis, cellulitis, osteomyelitis, tumor, avascular necrosis, Charcot joint, Legg-Perthes (LP) disease, and Osteochondritis Dissecans (OCD). Although the method is straightforward, there are technical and clinical factors that may affect interpretation of data. Asymmetries in flow may arise due to injection technique, interfering activity of bladder and/or bowel, vascular abnormalities, AV malformation, and venous backflow. The dynamic study is also sensitive to the effects of various modes of therapy. Consideration must be given to these technical and clinical factors for the avoidance of pitfalls in interpretation of the dynamic study.

MRI of disc space infection in infants and children. Report of 12 cases

The MR aspects of spondylodiscitis in pediatric patients were studied with a 0.5-Tesla supraconductive magnet: 12 patients were divided in two groups; acute disease (9) and period of sequelae (3). The first group was divided into two subgroups according to the age and the clinical findings: infants (2) and children (7). In infants, MR gave good visualization of the destruction of vertebrae and discs. Presuppurative abscesses appeared as light signals, their extent and position relative to the cord being clearly visualized in frontal and sagittal planes in T1-weighted images. In older children, there were a low vertebral signal and disappearance of the disc-vertebra borders on T1-weighted images and a high vertebral signal with a decreased and flattened disc signal on T2-weighted images. Frontal and sagittal planes were used. During the first month of antibiotic therapy, the follow-up scans showed no changes, and even disclosed a spread of the abnormal signal in the vertebral body. At the stage of sequelae, on T1 the spinal signal was normal with a decreased disc width and on T2 the disc signal was low while the vertebrae appeared normal.

Three-phase [99mTc]diphosphonate scintimetry in septic and nonseptic arthritis of the immature knee: an experimental investigation in dogs

We compared the informative value of dynamic and static [99mTc]diphosphonate ([99mTc]DPD) scintimetry in early septic arthritis (SA) and chronic nonseptic arthritis (NSA) of the knee in puppies. SA (n = 10), induced by injection of Staphylococcus aureus into one knee, was examined after 48 h. NSA (n = 6) was induced by weekly intraarticular instillation of 1% carrageenan and examined at 2 and 12 weeks. Epiphyseal and metaphyseal count ratios (CRs) between experimental and control joint were calculated in an angiographic phase (0-20 s), a "blood pool" phase (20-256 s), and a bone uptake phase (2 hs). Control dogs (n = 4) had a CR of 1.0 in all regions and phases, the coefficients of variation being 0.06 and 0.03 in dynamic and static phases, respectively. In NSA, all scintimetric phases showed decreased metaphyseal uptake and largely unchanged epiphyseal uptake. Generally, SA exhibited vastly increased angiographic uptake in all regions and increased epiphyseal blood pool uptake, whereas delayed epiphyseal uptake varied and delayed metaphyseal uptake tended to decrease. Two septic joints had generalized reduction in dynamic uptake, probably owing to increased intraarticular pressure; in one of these, dynamic uptake in the distal femoral epiphysis (FE) was totally absent, suggesting temporary circulatory arrest during the dynamic scanning procedure. The use of regional dynamic and static [99mTc]DPD scintimetry increased the pathophysiologic and diagnostic value of joint scintigraphy, especially with respect to the early detection of SA and its avascular complications.

Evaluation of metallic osseous implants with nuclear medicine

Nuclear medicine has proven to have a valuable role in the evaluation of osseous metallic implants, particularly with joint prostheses, but can assist with evaluation of other appliances as well. The nuclear arthrogram has become an invaluable adjunct to simultaneously performed radiographic contrast arthrography. This application has been best evaluated in what is one of the most common of orthopedic prosthesis problems, namely, loosening of total hip prostheses. Experience indicates that both sensitivity and specificity of loosening of the femoral component can be increased to over 90% through combined use of nuclear with radiographic contrast arthrography. Furthermore the combination of routine skeletal scintimaging with the nuclear arthrogram adds a significant dimension to precise localizing of the nuclear arthrographics agent In-111 chloride. Nuclear medicine also plays an important role in further evaluating the presence of infection associated with metallic implants with In-111 WBC preparations being superior to Ga-67 as the radiopharmaceutical tracer. Infection has been detected with a sensitivity of 73% and a specificity of 93% in our series using combined In-111 WBC and simultaneous skeletal imaging with conventional Tc-99m MDP. Acute infections are more readily identifiable than chronic in association with prostheses.

The child with acute leg pain

Diagnostic imaging is an essential component in the evaluation of a child with acute lower extremity pain or limp. Most, but not all, of the etiologies are traumatic. Frequently, the history and clinical examination are not specific. Radionuclide bone imaging is extremely rewarding in these circumstances. It represents the most useful examination used in evaluating the pathophysiology and full extent of the disorder. This article discusses the clinical presentation, pathophysiology, and characteristic imaging observations in the more common problems associated with hip and/or leg pain.

The scintigraphic and radiographic appearance of the ischiopubic synchondroses in normal children and in osteomyelitis

Five cases of hematogenous osteomyelitis of the ischiopubic synchondrosis (IPS) were encountered among 180 patients with osteomyelitis treated over a 5-year period. Symptoms were poorly localized in all these IPS osteomyelitis patients. The IPS can normally show expansion and irregular mineralization radiographically and focal hyperconcentration of radiophosphates on scintigrams. Findings are frequently asymmetrical negating comparison with the contralateral side. In the cases of osteomyelitis, radiographs were abnormal at the time of presentation in only one of these five cases. In two of the four patients who had radionuclide bone scans, activity at the IPS exceeded that seen in a normal control population, but all showed loss of definition of the IPS and regional increased uptake permitting an early diagnosis.