Scintigraphy of spinal disorders in adolescents

Osteoblastomas of the spine: a comprehensive review

Osteoblastomas are primary bone tumors with an affinity for the spine. They typically involve the posterior elements, although extension through the pedicles into the vertebral body is not uncommon. Histologically, they are usually indistinguishable from osteoid osteomas. However, there are different variants of osteoblastomas, with the more aggressive type causing more pronounced bone destruction, soft-tissue infiltration, and epidural extension. A bone scan is the most sensitive radiographic examination used to evaluate osteoblastomas. These osseous neoplasms usually present in the 2nd decade of life with dull aching pain, which is difficult to localize. At times, they can present with a painful scoliosis, which usually resolves if the osteoblastoma is resected in a timely fashion. Neurological manifestations such as radiculopathy or myelopathy do occur as well, most commonly when there is mass effect on nerve roots or the spinal cord itself. The mainstay of treatment involves surgical intervention. Curettage has been a surgical option, although marginal excision or wide en bloc resection are preferred options. Adjuvant radiotherapy and chemotherapy are generally not undertaken, although some have advocated their use after less aggressive surgical maneuvers or with residual tumor. In this manuscript, the authors have aimed to systematically review the literature and to put forth an extensive, comprehensive overview of this rare osseous tumor.

Osteoid osteoma

Osteoid osteomas consist of a nidus with surrounding sclerotic bone. The differential diagnosis covers a wide range of conditions due to the variable presentation of osteoid osteoma. The natural history is for regression to occur within 6 to 15 years with no treatment; however, this can be reduced to 2 to 3 years with the use of aspirin and non-steroidal anti-inflammatory drugs. Computed tomography-guided percutaneous techniques, including trephine excision, cryoablation, radiofrequency ablation, and laser thermocoagulation, are described.

Guidelines for paediatric bone scanning with 99mTc-labelled radiopharmaceuticals and 18F-fluoride

The purpose of these guidelines is to offer nuclear medicine teams a framework that could prove helpful in daily practice. The guidelines include information related to the indications, acquisition, processing and interpretation of bone scans in children, focusing primarily on (99m)Tc-labelled diphosphonate scintigraphy, and also recommendations with regard to the emerging use of PET with (18)F-fluoride.

Imaging of the postoperative spine

Spinal instrumentation techniques have expanded dramatically during the past several decades, but the search for the perfect operative approach and fixation system continues. Fixation devices are designed for the cervical, thoracic, lumbar, and sacral segments using anterior, posterior, transverse, videoarthroscopic, and combined approaches. In most cases, bone grafting also is performed, because instrument failure occurs if solid bony fusion is not achieved. Radiologists must understand the operative and instrumentation options. Knowledge of expected results, appearance of graft material, and different forms of instrumentation is critical for evaluating position of implants and potential complications associated with operative approaches and spinal fixation devices.

Interobserver reliability in the interpretation of diagnostic lumbar MRI and nuclear imaging

BACKGROUND CONTEXT

Assessment of patients with complaints of low back or leg pain varies with the subspecialty of the treating physician. The evaluation of the spine patient may include magnetic resonance imaging (MRI), bone scan, or single-photon emission computed tomography (SPECT) imaging. The interpretation of these tests and the examiner's biases will impact the outcome of patient treatment and the cost to the health-care system.

PURPOSE

To evaluate interobserver reliability of MRI and nuclear imaging studies and determine the predictability of nuclear medicine results based upon MRI findings.

STUDY DESIGN/SETTING

Retrospective radiographic review for patients with low back pain. MRI, planar bone scan imaging, and SPECT imaging techniques were evaluated.

PATIENT SAMPLE

Seventeen patients (80 lumbar levels) who presented to an orthopedic spine specialist with a complaint of mechanical low back or leg pain were randomly selected. Inclusion criteria were age greater than 21 years and a workup that included MRI, bone scan, and SPECT scan images.

OUTCOME MEASURES

Interobserver reliability was determined using kappa values (0.6 to <0.8=substantial; 0.8-1=perfect). Interobserver reliability was evaluated for all studies and compared with a "group consensus."

METHODS

A team of orthopedists and radiologists of varying experience levels were assembled to interpret the imaging studies. All readings were performed independently followed by group interpretation and discussion. The reviewers were asked to assess each lumbar level (L1-L2 through L5-S1). Phase one: Is the level degenerative? Is there a spondylolisthesis present? Does the level have Modic changes on MRI? Phase two: Based on the MRI, will the planar bone scan be positive? After this prediction, was the planar scan positive? Identify the lesion location (anterior column vs. posterior column). Phase three: Based on their assessment and predicted results on planar bone scan, was the SPECT scan able to improve this assessment?

RESULTS

High kappa values were demonstrated in the identification of a degenerative disc, spondylolisthesis, and Modic change (0.773, 0.728, and 0.669, respectively). Bone scan and SPECT scan yielded poorer kappa results (0.539 and 0.460, respectively). Reviewer-predicted bone scan results demonstrated a positive predictive value of 68% and a negative predictive value of 84%. Predicated SPECT results were similar (positive predictive value 66% and negative predictive value 84%). SPECT identified 24% more lesions in the lumbar spine when compared with bone scan.

CONCLUSIONS

MRI interpretation of the lumbar spine is comparable between specialties. Nuclear imaging studies (bone scan/SPECT) demonstrated a poorer correlation between examiners. The presence of MRI changes enables an accurate prediction of bone scan or SPECT scan findings. SPECT scan demonstrates an increased sensitivity in the detection of spinal abnormalities and the ability to localize a lesion when compared with planar bone scan.

Degenerative spondylolysis: a concise report of scintigraphic observations

OBJECTIVES

Spondylolysis is traditionally thought to be a diagnosis of adolescence and childhood, and is ascribed to mechanical stress through the immature pars interarticularis. Over the last 4 yr we have noted a presentation of spondylolysis in association with hypertrophic zygapophyseal joint disease in the lumbar spine in an older age group.

METHODS

Records of 94 patients presenting with low back pain were examined. A pattern of intense zygapophyseal joint uptake in association with extended uptake in the pars interarticularis was ascribed as degenerative spondylolysis.

RESULTS

The ages of the 94 cases ranged from 33 to 80 yr (mean 64 yr). There were 53 males and 41 females. In the group with degenerative spondylolysis the mean age was 72 yr, with four females and two males. None of these six patients gave a history of childhood spinal disease or back pain and all were relatively inactive in terms of current participation in sport. All cases of spondylolysis were confirmed by computed tomography scanning.

CONCLUSION

The finding of hypertrophic zygapophyseal joint disease in association with spondylolysis is easily recognized by scintigraphic tomographic imaging.

Espondilodiscites sépticas: diagnóstico e tratamento

Estudamos retrospectivamente 24 pacientes com espondilodiscite séptica de diferentes etiologias (hematogênica, primária e infantil) e os diferentes aspectos envolvidos em seu diagnóstico e tratamento. Constatamos que a velocidade de hemossedimentação é um bom parâmetro laboratorial para acompanhar a evolução da doença, mas deve ser sempre interpretada conjuntamente com o quadro clínico e os achados de neuroimagem. Biópsias devem ser reservadas para os casos de diagnóstico duvidoso e o tratamento clínico realizado sempre que afastadas as seguintes condições: sepse, déficit neurológico, deformidade severa, abscesso epidural e corpo estranho (discite primária). A abordagem cirúrgica deve ser planejada levando em conta o estágio da doença, sendo preferencialmente por via posterior nas fases supurativas e anterior nas demais. Baseados em nossa experiência e em revisão da literatura, propomos um algoritmo para orientar o diagnóstico e o tratamento das espondilodiscites sépticas.

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.

The role of single photon emission computed tomography in bone imaging

Single photon emission computed tomography (SPECT) of the bone is the second most frequently performed SPECT examination in routine nuclear medicine practice, with cardiac SPECT being the most frequent. Compared with planar scintigraphy, SPECT increases image contrast and improves lesion detection and localization. Studies have documented the unique diagnostic information provided by SPECT, particularly for avascular necrosis of the femoral head, in patients with back pain, for the differential diagnosis between malignant and benign spinal lesions, in the detection of metastatic cancer in the spine, for the diagnosis of temporomandibular joint internal derangement, and for the evaluation of acute and chronic knee pain. Although less rigorously documented, SPECT is being increasingly used in all types of situations that demand more precise anatomic localization of abnormal tracer uptake. The effectiveness of bone SPECT increases with the selection of the proper collimator, which allows one to acquire adequate counts and minimize the patient-to-detector distance. Low-energy, ultrahigh-resolution or high-resolution collimation is preferred over all-purpose collimators. Multihead gamma cameras can increase the counts obtained or shorten acquisition time, making SPECT acquisitions more practical in busy departments and also increasing image quality compared with single-head cameras. Iterative reconstruction, with the use of ordered subsets estimation maximization, provides better quality images than classical filtered back projection algorithms. Three-dimensional image analysis often aids lesion localization.

Evaluation of lower back pain with bone scintigraphy and SPECT

Bone scintigraphy and single photon emission computed tomography (SPECT) may be performed for evaluation of lower back pain, especially when a bone abnormality is suspected. Various patterns of tracer activity based on precise identification of the anatomic location of increased uptake may be observed and used to evaluate bones and joints. Lesions centered about the disk space and vertebral body include spondylodiskitis, metastatic disease, vertebral body fracture, and degenerative disease (disk disease, spondylosis deformans). In diskitis, tracer uptake has a vertical orientation. Metastatic involvement should be suspected in solitary lesions evaluated with SPECT when the area of increased uptake extends from the vertebral body into the pedicle. Fractures are seen on planar and SPECT images as a linear, horizontally oriented area of increased uptake centered in the vertebral body. In degenerative disease, increased uptake is centered about the disk space and may be seen in and project beyond the surface of the vertebral body. Lesions of the posterior arch (comprising the pedicle, lamina, and facet joints) include spondylolysis, pedicle lesions, osteoarthritis of the facet joints, and fracture of the transverse process. Scintigraphy may help differentiate long-standing asymptomatic spondylolysis from ongoing disease. In osteoarthritis of the facet joints, SPECT may be used to select patients to be treated with therapeutic injections. Increased uptake in the transverse process most often indicates a fracture, although tumors may also occur in this location. These findings at planar bone scintigraphy and SPECT allow differentiation of common pathologic conditions and can lead to a specific diagnosis.

Optimization of MRI pulse sequences to visualize the normal pars interarticularis

Magnetic resonance imaging (MRI) is a potentially useful means of detecting acute pars stress fractures. However, recent publications have highlighted the deficiencies of routine MRI in evaluating the pars interarticularis. Twenty-nine volunteers underwent thin section, multi-planar MR examinations of the lumbar spine to evaluate whether the normal pars could be more reliably demonstrated. MRI examinations were performed with sagittal and reserve angle oblique axial T1W images, and also 3D sagittal gradient echo images with reverse angle reconstructions. Sagittal STIR images were also acquired in 14 cases. Two hundred and ninety pars were evaluated, of which 66% were deemed definitely intact (type I) on the sagittal T1W images alone (continuous marrow throughout the pars). However 93% were deemed intact when all images were reviewed together. The majority of pars defects occur at L4/L5, and 74% of these were intact on the sagittal T1W sequence alone, and 90% on combined sequences. Eighteen pars (6%) were considered to be hypointense (type II) after review of all sequences, but appeared otherwise intact. One volunteer had bilateral definite pars defects (type IV) at L5 on all sequences. This study indicates that improved visualization of the normal pars interarticularis can be achieved with optimized MRI.

Suspecting lumbar spondylolysis in adolescent low back pain

Spondylolysis in the athletic adolescent and preadolescent is common enough that primary care practitioners should be familiar with its frequency and its progression from pars interarticularis stress fracture to spondylolysis and to spondylolisthesis. One-half of all pediatric back pain in athletic patients is related to disturbances of the posterior elements including spondylolysis, which presents as low back pain aggravated by activity, frequently with minimal physical findings. Failure to suspect, hence to diagnosis, a pars stress fracture or early spondylolysis is common and a misdiagnosis of lumbosacral strain is often made. A complicating factor in early diagnosis is the fact that plain radiographs, even with oblique films, may not be helpful at the stress fracture stage, and other imaging techniques (bone scan possibly with single photon emission computed tomography [SPECT]) must be used early in the diagnostic process. In the primary care setting, an early diagnosis of posterior element involvement in low back pain either at the stage of pars stress fracture or early spondylolysis can prevent progression of the disease and the need for aggressive intervention for a more significant defect. We present three adolescent and preadolescent athletes with low back pain in whom a high index of suspicion led to the early diagnosis of pars stress fracture or spondylolysis. All three had different stages of spondylolysis, and one illustrates the clinical utility of the one-legged hyperextension test. The ease with which early disease may be treated further supports efforts by primary care practitioners to suspect and diagnose pars stress fracture and early spondylolysis.

SPECT bone scanning of the spine

Radionuclide bone scanning is a well accepted method for uncovering a variety of bony lesions including abnormalities of vertebral bodies that may be causing spinal pain. Single photon emission computed tomography (SPECT) is especially useful in such an evaluation because it allows for precise localization of a lesion to the vertebral body, disc space, or vertebral arch. This anatomic distinction is necessary in order to accurately diagnose the underlying condition detected by the bone scan. Most bony abnormalities result in focal areas of abnormal tracer activity but do not affect all components of a vertebra with equal frequency nor have a random pattern of involvement. Vertebral diseases tend to conform to predictable patterns that can be more readily identified by SPECT than planar imaging. Metastatic tumors commonly involve the posterior portion of the vertebral body, often in combination with a pedicle. Extensive abnormalities involving the vertebral body and vertebral arch, but sparing the pedicles, are usually benign as are lesions isolated to articular facets and lamina or disc space. Postoperative patients have additional potential problems including pseudarthrosis and complications following use of internal fixation devices including pedicle screws. Nuclear medicine physicians must speak the language of their referring physicians who are anatomically oriented and used to the exquisite morphologic detail of computed tomography (CT) and magnetic resonance imaging (MRI). SPECT allows for greater anatomic information compared with planar imaging as well as straightforward comparison with other tomographic-based studies such as CT and MRI.

Bone SPECT imaging of the painful back

Bone SPECT imaging offers advantages over planar techniques based on improved contrast enhancement plus tomographic effect, with the latter allowing for precise anatomic localization of an abnormality. This is important when evaluating patients with back pain because placement of a lesion in the vertebral body, component of the vertebral arch, or disc space region significantly affects diagnostic possibilities and, in some circumstances, can effectively exclude malignancy in favor of benign disease. Such an approach to SPECT interpretation requires high-quality images capable of precise anatomic placement of a lesion and a systematic method of analysis based on recognition of normal anatomic relationships plus knowledge of the common presentations of bony abnormalities shown on SPECT scanning.

Oblique angle bone SPECT imaging of the lumbar spine, pelvis, and hips. An anatomic study

Bone SPECT offers advantages over planar imaging in detecting skeletal lesions because of increased contrast enhancement and tomographic effect with the latter, allowing for precise anatomic localization of an uncovered abnormality. However, tomographic sections of curved structures or regions obliquely oriented to the reconstruction plane may have inherent limitations as far as case of image interpretation, which can be overcome by oblique reorientation of the SPECT views. A method for oblique angle presentation of the lumbar spine, pelvis, and hips has been developed with results correlated with radiographic tomograms of a phantom to order to ensure correct anatomic orientation. These oblique SPECT images allow for easier differentiation between facet and pars interarticularis abnormalities, as well as improved imaging of hips and sacrum.