Nuclear medicine topics in pediatric musculoskeletal disease: techniques and applications

[Acute osteomyelitis: epidemiology, clinical manifestations, diagnosis and treatment]

BACKGROUND AND AIMS

The present study focuses on the epidemiology, clinical and laboratory data, and management of osteomyelitis in a pediatric third level hospital.

METHODOLOGY

All cases of children under 15 years-old admitted with osteomyelitis between 2000 and 2011 were retrospectively reviewed until July 2006, then prospectively from then until 2011.

RESULTS

A total of 50 patients were identified (52% males) with median age at diagnosis of 2 years. Principal onset manifestations were pain (94%), functional impairment (90%) and fever (72%). The femur (32%), fibula (28%) and calcaneus (22%) were most affected bones. Leucocytosis > 12.000/μl was found in 56%, elevated ESR > 20 mm/h in 26%, and elevated CRP > 20 mg/L in 64%. Blood culture was positive in 20%, with group A streptococcus being the most frequently isolated bacteria (11%). All diagnoses were confirmed by a (99)Tc scintigraphy bone scan. Antibiotic therapy was initially intravenously (mean time of administration: 10 days ± 3 SD), followed by oral medication (mean time of administration: 18 days ± 6 SD). Surgery was necessary in 3 patients. Evolution of all cases was excellent, despite 3 exceptions that resolved over time.

CONCLUSIONS

The current short-term intravenous therapy led to shorter hospitalizations. There were no statistically significant differences between time from clinical onset or in CRP levels at discharge compared to long-term therapies prior to 2006.

Functional imaging of infection: conventional nuclear medicine agents and the expanding role of 18-F-FDG PET

A growing body of literature suggests that 18-fluorine fluorodeoxyglucose positron emission tomography ((18)F-FDG PET), particularly when combined with CT, is a useful tool for the detection of infectious and inflammatory disease processes. This article will briefly review the data to date on the use of FDG PET in diagnosing musculoskeletal infections and fever of unknown origin, comparing it to conventional scintigraphic techniques in both adults and, when available, in children.

[The chronically limping child]

Chronic limping in children usually indicates the presence of an underlying organic lesion. Clinical evaluation establishes the site and type of limping. It may suggest a neurological or mechanical lesion or locoregional etiology at the level of the hip or pelvis. Plain radiographs and ultrasound are firstline imaging techniques. The diagnosis may be delayed either due to ignorance of age-specific entities or false positive or negative results on plain films and ultrasound. MRI now plays a major role for diagnosis. Multiple potential underlying etiologies including trauma, infections, arthritides or tumors are best evaluated with MRI. The MRI examination should not be limited only to the hip joint.

Postoperative infection

Infectious disease complicating surgery involving the musculoskeletal system is one of the most important causes of postoperative morbidity and mortality. Timely detection and accurate localization of infectious processes have important clinical implications and are critical to appropriate patient management. Imaging studies can play an important role in the detection of infection and can help guide appropriate clinical management. The diagnosis of postoperative infection can be made by a variety of imaging modalities. This article reviews the various methods and modalities available for the detection of postoperative infection.

Diagnostic imaging of pediatric hematogenous osteomyelitis: lessons learned from a multi-modality approach

Pediatric hematogenous osteomyelitis may present highly variable radiological expression, which is influenced by the age and condition of the patient, the virulence of the causative agent, the stage of the disease, or the selected imaging tool. Given the multiplicity of available modalities and the multi-faceted nature of the process, purposeful imaging of pediatric hematogenous osteomyelitis may be difficult. In order to avoid diagnostic delays and complications, familiarity with the variable expression of the disease and assumption of the potentialities, roles and limitations of the various imaging modalities is required. In this pictorial essay we review, illustrate and discuss, in a multi-modality approach, the various radiological patterns that may be found in pediatric hematogenous osteomyelitis, with emphasis on strategies, staging, uncommon distribution patterns, and differential diagnosis.

Malignant bone tumors and limb-salvage surgery in children

Limb-salvage surgery plays a major role in the management of children with malignant bone tumors. This article provides background on the clinical presentation and imaging evaluation of children with malignant bone tumors and describes various limb-salvage procedures used in the treatment of these children.

Radionuclide bone imaging: an illustrative review

Bone scintigraphy with technetium-99m-labeled diphosphonates is one of the most frequently performed of all radionuclide procedures. Radionuclide bone imaging is not specific, but its excellent sensitivity makes it useful in screening for many pathologic conditions. Moreover, some conditions that are not clearly depicted on anatomic images can be diagnosed with bone scintigraphy. Bone metastases usually appear as multiple foci of increased activity, although they occasionally manifest as areas of decreased uptake. Traumatic processes can often be detected, even when radiographic findings are negative. Most fractures are scintigraphically detectable within 24 hours, although in elderly patients with osteopenia, further imaging at a later time is sometimes indicated. Athletic individuals are prone to musculoskeletal trauma, and radionuclide bone imaging is useful for identifying pathologic conditions such as plantar fasciitis, stress fractures, "shin splints," and spondylolysis, for which radiographs may be nondiagnostic. A combination of focal hyperperfusion, focal hyperemia, and focally increased bone uptake is virtually diagnostic for osteomyelitis in patients with nonviolated bone. Bone scintigraphy is also useful for evaluating disease extent in Paget disease and for localizing avascular necrosis in patients with negative radiographs. Radionuclide bone imaging will likely remain a popular and important imaging modality for years to come.

Benign bone tumors in children

When children present for evaluation of bone tumor, great anxiety often occurs among the family. Usually the diagnosis of a benign bone tumor can be made easily with plain radiographs without biopsy. Most have a good outcome. However, occasionally, serious complications can develop. Moreover, the physician must be aware of the possibility of the malignant tumors. To avoid errors in the evaluation and treatment of this heterogeneous group of tumors, the clinician should have a good knowledge base of common bone neoplasms and correlate the clinical, radiographic, and pathologic findings. In this article, history, diagnosis, evaluation, treatment, and management of common types of benign tumors of bone commonly seen in children and adolescents are reviewed in the light of current literature.