The role of bone scan and radiography in the diagnostic evaluation of suspected pedal osteomyelitis

The authors reviewed the three-phase bone scans and radiographs of 24 patients with suspected pedal osteomyelitis who also had histologic confirmation of the diagnosis. Twenty patients had a pedal ulcer, cellulitis, or necrosis. Sensitivity and specificity of bone scanning were 70% and 43% respectively. Sensitivity and specificity of radiography were 70% and 50% respectively. The non-invasive diagnosis of pedal osteomyelitis remains problematic due to the poor specificity of bone scans and radiographs.     

Value of a 24-hour image (four-phase bone scan) in assessing osteomyelitis in patients with peripheral vascular disease

The delayed images of the four-phase 99mTc phosphonate bone scan are compared with the delayed images of the three-phase study in patients with diabetes mellitus and/or peripheral vascular disease and suspected osteomyelitis. Three-phase bone imaging includes an immediate postinjection radionuclide angiogram, a blood-pool image, and delayed static images to 7 hr. The four-phase study adds a 24-hr static image. The scan is positive for osteomyelitis if images show progressively increasing lesion to background activity ratios over time. The results of analyzing 21 three- and four-phase bone scans in 17 patients were correlated with clinical course, cultures, and/or x-rays, gallium scans, and CT scans. The accuracy of four-phase bone imaging for diagnosing osteomyelitis was 85%; for three phase, 80%. Sensitivity for four phase was 80%; specificity was 87%. Sensitivity for three phase was 100%; specificity was 73%. Since overall accuracy of the four-phase study is slightly better than three phase, in these patients with diabetes mellitus and/or peripheral vascular disease, the addition of a 24-hr image, creating a four-phase bone scan, is recommended.     

Effect of soft-tissue pathology on detection of pedal osteomyelitis in diabetics

Three-phase bone scans were performed on 30 diabetic patients suspected of having acute pedal osteomyelitis; 23 also had a pedal ulcer, seven had coexisting cellulitis, and 14 had diminished pedal pulses. Fifteen patients were receiving antibiotics at the time of the scan. A tissue diagnosis was available in 18 patients and 12 had no clinical evidence of infection on follow-up. Focal arterial hyperemia combined with focally increased activity on blood-pool and delayed (2-3 hr) scans were interpreted as acute osteomyelitis. Scans showing venous hyperemia were interpreted as soft-tissue pathology without acute osteomyelitis. Companion radiographs were reviewed independently. The sensitivity and specificity of the scans for osteomyelitis were 0.94 and 0.79, respectively, while radiographic sensitivity was 0.93 and specificity was 0.50. The presence of soft-tissue ulcers or cellulitis, peripheral vascular disease, or recent antibiotic therapy had no significant adverse effect on the accuracy of the three-phase scan in diagnosing osteomyelitis.     

Multifocal osteomyelitis in childhood. Review by radionuclide bone scan.

Multifocal osteomyelitis is considered an uncommon complication of acute osteomyelitis. Over a 3-year period, 136 infants and children who had a final diagnosis of acute osteomyelitis were reviewed, and multifocal osteomyelitis was detected in 27 (19%) patients. The major age peak of acute osteomyelitis was between 6 weeks and 3 years (46%). Two age peaks were found for multifocal disease-less than 6 weeks (38%), and 9 to 12 years (44%). Three patients with multifocal disease had septicemia and photon-deficient areas on bone scans. Another adolescent group had nonspecific bone and joint pain that in some cases persisted for more than 3 months and were finally diagnosed as multifocal osteomyelitis. Organisms were isolated in 15/27 (56%). Multifocal osteomyelitis is well recognized in the neonatel age group. However, it occurs more commonly than previously described in older patients. This higher incidence can most likely be attributed to the higher use of the radionuclide bone scan early in the disease and the high sensitivity of the scan for the detection of osteomyelitis.     

Scintigraphic evaluation of diabetic osteomyelitis: concise communication

We have reviewed the three-phase bone scans, radiographs, and histologic findings of 39 diabetic patients with serious foot problems. The sensitivity and specificity of bone scans were 83% and 75%, respectively, for osteomyelitis of the small bones of the foot. The positive and negative predictive values were 87% and 69%, respectively. The radiographs were less sensitive (62%) and less specific (69%), with predictive values of 80% (positive) and 47% (negative).     

Osteomyelitis: diagnosis with (99m)Tc-labeled antigranulocyte antibodies compared with diagnosis with (111)In-labeled leukocytes--initial experience

PURPOSE: To compare a technetium 99m-labeled murine immunoglobulin M monoclonal antigranulocyte antibody that binds to human polymorphonuclear leukocyte CD15 antigens with indium 111 ((111)In)-labeled leukocytes in the diagnosis of appendicular skeletal osteomyelitis. MATERIALS AND METHODS: Twenty-four patients suspected of having infected joint replacement (n = 12), diabetic pedal osteomyelitis (n = 8), or long bone osteomyelitis (n = 4) were imaged 5, 30, 60, and 120 minutes after antibody injection. Following injection, one patient experienced moderate joint pain exacerbation that resolved spontaneously. Patients underwent imaging with (111)In-labeled leukocytes and three-phase bone imaging. All studies were interpreted alone. Images obtained in antibody and (111)In-labeled leukocyte studies were also interpreted with the bone scans. One reader, without knowledge of other study results or final diagnoses, reviewed and interpreted images in a random order. Sensitivity, specificity, and accuracy were calculated for the antibody study at each time point, the (111)In-labeled leukocyte study, the three-phase bone scanning procedure, and dual-tracer studies. RESULTS: There were 11 cases of osteomyelitis. Bone scintigraphy was sensitive (1.0) but nonspecific (0.38). Images obtained in the 120-minute antibody study were sensitive (0.91), moderately specific (0.69), and comparable to those obtained in the (111)In-labeled leukocyte study (0.91 sensitivity, 0.62 specificity). When interpreted with bone scans, images obtained in the antibody and (111)In-labeled leukocyte studies showed improved sensitivity and specificity (1.0 and 0.85 and 1.0 and 0.77, respectively). CONCLUSION: Use of the monoclonal antigranulocyte antibody was comparable to the use of (111)In-labeled leukocytes in the diagnosis of appendicular skeletal osteomyelitis. The combined results of the monoclonal antibody study and bone scanning were more accurate (0.91) for diagnosing this entity than were the results of any of the other studies.     

Diagnosis of osteomyelitis by MR imaging

Bone scans are highly sensitive for the diagnosis of acute osteomyelitis, but the difficulty of separating bone-marrow processes from soft-tissue disease limits the specificity and accuracy. A diagnostic technique capable of distinguishing bone-marrow processes from soft-tissue disease would improve the diagnostic accuracy of osteomyelitis. To evaluate the use of MR in the diagnosis of osteomyelitis, MR examinations were performed in 35 patients with suspected acute osteomyelitis. Twelve of these were proved to have osteomyelitis either by surgery (nine patients) or by clinical follow-up (three patients). In the other 23, osteomyelitis was excluded by surgery (12 patients) or by the clinical course (11 patients). Evidence of osteomyelitis on MR consisted of abnormalities of the bone marrow with decreased signal intensity on the T1-weighted images and increased signal intensity on the T2-weighted or short-T1 inversion recovery (STIR) images. MR and bone scintigraphy were interpreted by two radiologists who were given no clinical information other than to rule out osteomyelitis. The sensitivities of MR and static bone scan were 100% for bone-marrow abnormality. Because bone-marrow abnormality in osteomyelitis associated with healing fractures was incorrectly diagnosed by MR (one case) and bone scintigraphy (two cases), the sensitivities of MR and scintigraphy for the diagnosis of osteomyelitis were 92% and 82%, respectively. The specificities of MR and scintigraphy were 96% and 65%, respectively (p less than .05). The overall accuracy for the diagnosis of osteomyelitis was 94% for MR and 71% for bone scan (p less than .05). Because of its ability to separate soft-tissue disease from underlying bone marrow, MR may be used to evaluate patients with positive bone scintigraphy to improve the specificity and accuracy of diagnosis for osteomyelitis.     

Osteomyelitis of the foot in diabetic patients: evaluation with plain film, 99mTc-MDP bone scintigraphy, and MR imaging

Diagnosis of osteomyelitis of the foot in diabetic patients may be difficult because of the coexistence of chronic cellulitis, vascular insufficiency, and peripheral neuropathy. This study compared the diagnostic accuracies of plain films, bone scans, and MR imaging studies in diabetic patients with suspicion of osteomyelitis of the foot. Twenty-nine plain radiographs, 20 bone scans, and 30 MR studies were obtained in 24 patients. Twenty-nine bones from 14 patients were pathologically proved either positive (25 bones) or negative (four bones) for osteomyelitis. Another 15 bones (10 patients) studied with MR had no pathologic proof, but the bones healed with only local wound care and/or a short course of oral antibiotics. These patients had trauma, cellulitis, or unhealed ulcers. The sensitivity and specificity of plain films were both 75%. Bone scans had a very low specificity (100% false-positive rate). A negative bone scan should strongly exclude the probability of osteomyelitis. Unlike the findings in previous reports, MR had much higher sensitivity and specificity than bone scans in detecting osteomyelitis in diabetic patients. When the 10 patients without pathologic proof (those who presumably had neuroarthropathy, vascular insufficiency, and/or cellulitis) were included, the sensitivity and specificity of all three techniques decreased. Our experience with this small group of patients suggests that MR is a useful imaging technique for diagnosing osteomyelitis of the foot in diabetic patients.     

MRI in diagnostic evaluation of osteomyelitis in children

Several MRI investigations for detecting or excluding acutre and non-post-traumatic chronic osteomyelitis were performed in 31 children, osteomyelitis was evident in 21 patients. The sensitivity of MRI for osteomyelitis was 90%, and specificity was 100%. In children with confirmed osteomyelitis 23 follow-up investigations were carried out in order to evaluate duration of the medullary edema. in uncomplicated cases only in treated by antibiotics edema regression was evident after 4 weeks and completed after 12–16 weeks. In cases in whom extended concomitant soft-tissue infection was depicted regression of edema was prolonged independent of surgical intervention. The study reveals that at onset of acute osteomyelitis in children MRI can replace technetium 99m-labeled scintigraphy and reduce plain-film investigations. The results support the usefulness of MRI in discrimination of isolated soft-tissue infection and noninfectious diseases of bone.     

Acute osteomyelitis in children: combined Tc-99m and Ga-67 imaging

This retrospective study was done to determine the value of combined bone (technetium-99m methylene-diphosphonate) and gallium-67 citrate imaging in selected children with complicated clinical situations. Thirty-one children were evaluated for suspected osteomyelitis by bone scan followed within 4 days by a gallium scan. These 31 children represented a subpopulation in whom the Tc-99m scan is known to be potentially unreliable in diagnosing acute osteomyelitis. Eight children had acute osteomyelitis by strict criteria, while 23 did not. The bone scan successfully identified five of the eight with osteomyelitis but was positive in ten of the other 23. The gallium scan correctly identified all eight with osteomyelitis but was positive in seven of the other 23. The gallium scan was significantly less specific when the suspected lesion was in the extremities compared with central locations; causes of false-positive gallium scans included fracture and juvenile rheumatoid arthritis. Combined gallium and bone scanning increased accuracy of the scintigraphic diagnosis of acute osteomyelitis. Both tests may, however, be abnormal in conditions other than osteomyelitis. These findings emphasize the importance of correlating all imaging studies in detection of osteomyelitis.     

Radionclide imaging in skeletal inflammatory and ischemic disease in children.

Sixty-five children were evaluated for presence of skeletal inflammatory and ischemic disease with bone scans and roentgenograms. Several characteristic scintigraphic patterns were observed. Bone scans were significantly more sensitive than roentgenograms in early diagnosis of osteomyelitis and its differentiation from cellulitis, septic arthritis, and bone infarction. The child presenting with possible inflammatory bone disease now is benefited by this important refinement in diagnosis. Faced with the difficult dilemma of choosing appropriate therapy in these frustratingly similar problems, the physician can integrate the clinical findings with nuclear imaging to arrive at early appropriate diagnosis and management.     

Indium-111-labeled leukocyte scintigraphy: diagnosis of subperiosteal abscesses complicating osteomyelitis in a child

Preoperative 111In-labeled leukocyte scintigraphy demonstrated extensive subperiosteal abscesses complicating acute bilateral tibial osteomyelitis in a child. Plain radiographs showed only marked soft-tissue swelling; three-phase bone scintigraphy depicted both "hot" and "cold" areas consistent with acute osteomyelitis.     

Imaging findings of complications affecting the upper extremity in intravenous drug users: featured cases

Infections generally occur in intravenous drug abuse (IVDA) patients, most commonly affecting the spine and proximal joints. Numerous serious musculoskeletal complications of IVDA may involve the upper extremity, however. Soft-tissue complications in the upper extremity of IVDA patients include cellulitis, ulceration, abscess, pyomyositis, septic bursitis, tenosynovitis, and necrotizing fasciitis. Foreign bodies in soft tissue due to needle fragments are common findings. Primary bone and joint IVDA complications include osteomyelitis (acute and chronic) and septic arthritis. Other IVDA complications in the upper extremity affecting blood vessels and lymphatics include hematoma, arterial aneurysm and pseudoaneurysm, thrombosis, thrombophlebitis, "puffy hand" syndrome, and lymphadenopathy. These complications usually present as urgent issues requiring prompt and accurate evaluation in the acute setting. Diagnostic imaging not only aids in making the correct diagnosis but also permits precise definition of the location and extent of these abnormalities. We review the imaging findings and illustrate a wide range of disabling and even life-threatening complications affecting the upper extremity of IVDA patients that require early diagnosis for optimal outcome.     

Articular complications in sickle cell-thalassemia after childhood. Diagnostic problems

The osteoarticular complications of drepanocytosis-thalassemia (DT) include: 1) bone infarction, or avascular necrosis (AVN), common at all ages; 2) acute septic arthritis and hematogenous osteomyelitis, that usually affect infants and children. Early diagnosis and treatment of the osteoarticular infectious complications is imperative, to maximize the chances of a favorable outcome, and to prevent the sequelae, ie pathological fractures, chronic osteomyelitis. Early roentgenographic features of involved areas are similar in acute osteomyelitis and in AVN--both of which cause painful bone crises, so as to make osteomyelitis (OM) a diagnostic challenge. Four cases of DT are reported. The patients, 17 to 37 years old, presented with bone infarcts. One of them (the youngest) had also multiple osteomyelitis of long bones. The 99m-Tc-MDP bone scans, performed only on the youngest patient, affected by OM, revealed increased uptake in both AVN and in OM locations, without differential diagnostic features. After a review of the literature, a diagnostic protocol is suggested, based on 99m-Tc colloid marrow scintigraphy for the early differential diagnosis between acute OM (normal or slightly-increased uptake), chronic OM (markedly increased uptake), and AVN (decreased uptake). Furthermore, MR imaging is stressed as the most promising tool, in the next future, for this kind of differential diagnosis.     

99mTc-depreotide in the evaluation of bone infection and inflammation

BACKGROUND AND AIM: (99m)Tc-depreotide is a (99m)Tc-labelled somatostatin analogue, with high affinity for the 2, 3 and 5 subtypes of somatostatin receptors. These particular receptors are over-expressed on the surface of activated leucocytes, which mediate inflammatory response. Based on this property this study tried to investigate whether (99m)Tc-depreotide scintigraphy could be a useful complementary method in the investigation of bone infection and inflammation. METHODS: Twenty-three patients, who were investigated for probable osteomyelitis, underwent three-phase bone scintigraphy followed by (99m)Tc-depreotide scintigraphy. Clinical and laboratory findings, complementary imaging procedures, clinical follow-up and bone biopsy established the final diagnosis. (99m)Tc-depreotide scintigraphy was performed 3 h after the intravenous administration of 555-740 MBq of the radiopharmaceutical. Scintigraphic images were, at first, blindly interpreted alone and then in comparative assessment with bone scans. RESULTS: (99m)Tc-depreotide was positive in 12/12 cases of active osteomyelitis, one case of recent femoral head osteonecrosis and 6/9 rheumatoid arthritis sites. Negative (99m)Tc-depreotide scans were acquired in five cases of 'no-inflammation' (an uncomplicated fracture, an aseptic loosening of prosthesis, an old osteonecrosis, a healed and a successfully treated osteomyelitis), as well as in 14/14 total sites of degenerative arthritis-osteoarthropathy. In five cases (septic arthritis, periodontal and soft tissue infections) (99m)Tc-depreotide was positive, though spatially discordant with bone scintigraphy, delineating precisely the focus of infection. CONCLUSION: (99m)Tc-depreotide can be a useful complementary imaging method in the evaluation of bone infection and inflammation. Its combination with three-phase bone scintigraphy seems to be accurate in localizing the infection foci and determining the activity of the inflammatory processes.     

Early scintigraphic findings of occult femoral and tibial fractures in infants

Differentiation of occult skeletal injuries from early acute osteomyelitis in infants and young children is important clinically. The Tc-99m MDP scintigraphic findings in six patients who had occult femoral or tibial fractures were reviewed. The images obtained early (at 1-4 days from the onset of symptoms) shared the common characteristic finding of a subtle but definite, generalized increased uptake of the tracer along the entire length of the injured bone. This pattern of uptake was similar regardless of the type of fracture. These were different from the focal abnormalities that have been observed in early acute osteomyelitis. In the absence of an extensive cellulitis or a vascular occlusive disease, a bone image showing a mild diffuse uniform increased uptake along the entire length of the tibia or femur in infants and young children with lower extremity pain of less than 1 week's duration should suggest the diagnosis of occult skeletal fractures.     

Intramedullary and extramedullary fat globules on magnetic resonance imaging as a diagnostic sign for osteomyelitis

We retrospectively studied the frequency of persistent foci of fat signal on magnetic resonance (MR) imaging in osteomyelitis to assess its frequency, cause and diagnostic value. The radiographs and MR scans of 100 patients with a final diagnosis of osteomyelitis referred to a specialist orthopaedic oncology service with the presumptive diagnosis of a bone tumour were reviewed. The MR signal and morphological characteristics were recorded with particular attention to the presence of persistent fat signal within the infected area, which was classified as diffuse or focal. Seventeen cases were classified on radiographic grounds as acute, 63 as subacute and 20 as chronic osteomyelitis. In the acute group 12 (70%) showed replacement of the marrow with fluid containing residual fatty signal, diffuse in seven and focal in five cases. Two cases showed predominantly fatty marrow with very early marrow oedema and three cases (18%) showed replacement of marrow fat with fluid and no residual fatty foci. None of the subacute group showed foci of fatty signal and two cases of inactive sclerosing osyeomyelitis in the chronic group showed restoration of normal marrow. Persistent fatty signal within the bone as well as soft tissues on MR imaging is a frequent finding in acute osteomyelitis. Radiological–pathological correlation suggests that the increasing intramedullary pressure leads to septic necrosis with death of the lipocytes and release of free fatty globules. This characteristic, but not pathognomonic, MR finding supports the diagnosis of osteomyelitis and may help to exclude the presence of a tumour.     

Differentiation of bone and bone marrow infarcts from osteomyelitis in sickle cell disorders

To determine whether imaging techniques can differentiate osteomyelitis from bone infarction in sickle cell disorders, 39 sets of bone scans (BS) and bone marrow scans (BMS) were performed on 31 patients with sickling disorders and bone pain. In addition, three patients who had either a BS or a BMS were included. Results were analyzed according to whether scans were performed three days or less (Period 1), four to six days (Period 2), or seven or more days (Period 3) after the onset of pain. Regardless of the period, all but five BMS for 34 episodes of assumed infarction showed decreased uptake. BS findings varied depending on the time interval, with none of the ten in Period 1 showing increased uptake, but all 11 in Period 3 showing increased uptake. However, in Period 2, about half of the 13 BS showed increased uptake. All three patients with osteomyelitis in Period 3 had increased uptake on BS. The BMS done in one of these patients showed decreased uptake. Three patients with cellulitis had normal BS and BMS. One patient with septic arthritis had normal BMS, but slightly increased uptake on BS. Although typical imaging patterns are present in early and late infarction (Periods 1 and 3), the patterns for late infarction may not differ from those of advanced osteomyelitis. Therefore, imaging studies are only of value in differentiating infarction from osteomyelitis when both BS and BMS are performed soon after the appearance of symptoms.     

Infection in diabetic osteoarthropathy: use of indium-labeled leukocytes for diagnosis

Indium-111 labeled leukocyte imaging was compared with three-phase skeletal scintigraphy as a means of determining whether osteomyelitis was complicating diabetic osteoarthropathy. Three-phase scintigraphy demonstrated increased activity in both infected and noninfected osteopathic bone, with a sensitivity of 75% and a specificity of 56% for osteomyelitis. Leukocyte imaging had the same sensitivity but was most helpful for excluding infection (specificity, 89%) when three-phase imaging could not. Abnormal leukocyte localization was seen at the primary site of infection in all cases within 4 hours after injection. Disadvantages of leukocyte imaging included long preparation time, low count rates resulting in poor spatial resolution, and absence of bone landmarks, which made it difficult to differentiate soft tissue from bone infection.     

Quantitative bone gallium scintigraphy in osteomyelitis

Gallium imaging offers many practical advantages over indium-111-labeled leukocyte imaging, and calculating quantitative ratios in addition to performing the routine bone-gallium images allows accurate and easy evaluation of patients with suspected osteomyelitis. To add objectivity and improve the accuracy and confidence in diagnosis of osteomyelitis, quantitative comparison of abnormalities seen on bone scans and gallium scans was performed. One hundred and ten adult patients with 126 sites of suspected osteomyelitis were evaluated and categorized by gallium-to-bone ratios, gallium-tobackground ratios, and spatial incongruency of gallium and bone activity. Combined evaluation using these criteria gave a 70% sensitivity and 93% specificity for the diagnosis of osteomyelitis.