Spectrum of Combined Tc99m-HDP SPECT/CT Findings in Benign and Malignant

Bone Conditions: Additional or Redundant Information? Fabio Paes MD, Dimitrios Kalkanis MD, Osama Gomaa MD and Aldo Serafini MD

Department of Radiology, Division of Nuclear Medicine, University of Miami, Miami, Florida

All patients received 99mTc-diphosphonate IV. The examination

was performed as three phase scintigraphy of the affected part or a

single delayed phase. A series of 60 images were acquired

immediately, within the first minute after radiotracer injection.

Static images of radiotracer distribution in the blood pool, each of

30 seconds duration, were acquired until 6 minutes after injection.

Three to four hours after radiotracer injection, planar whole-body

scintigraphy and spot planar scintigraphy of the region of interest

were performed. A SPECT/CT, a hybrid camera (Symbia, Siemens)

consisting of a dual-head gamma camera and a helical MDCT

scanner was used. Counts from the 15% energy windows at 140 keV

were acquired into a 128 × 128 matrix (pixel size, 4.6 × 4.6 mm). CT

was always performed as low-dose CT: 130 kV; 20 mAs; rotation

time, 0.8 seconds; collimation, 2 × 1 mm. SPECT/CT images of the

area of interested, identified or not in the whole bode scan, were

obtained after the planar imaging acquisition.

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AJR Am

Bone scintigraphy is frequently used for the diagnostic evaluation of

orthopedic disorders because altered bone metabolism can be

detected before morphologic changes are detected with planar

radiography. Furthermore, whole-body scintigraphy can be used to

assess the integrity of the entire

skeleton. It is also well known, however, that bone scintigraphy has

low specificity because of its comparatively poor depiction of

morphologic features. Therefore, in cases of focally enhanced bone

metabolism, information from other imaging procedures is

necessary to establish a diagnosis. Although, the scintigraphic

images are usually compared to planar radiographs, these

frequently may not completely show pathologic changes due to the

presence of overlying bone or artifacts.

New hybrid SPECT/CT systems are capable of overcoming these

difficulties providing both metabolic and discrete anatomic

information. Recent data have shown that SPECT/CT imaging

increases the diagnostic accuracy and reader confidence of benign

and malignant focal bone conditions. Also, a single SPECT/CT

study can obviate additional imaging in a great number of patients.

We present here examples of benign and malignant bone pathology

in which SPECT/CT imaging provided additional diagnostic and

management value over planar scintigraphy.

Introduction

Technique

Bibliography

Possible Applications Abstract Whole body Bone Scintigraphy has been an established sensitive

method for evaluation of bone pathology. However, it lacks

specificity and adequate anatomical correlation, even when SPECT

technique is used. Bone Scintigraphy SPECT/CT has emerged as an

important modality in the diagnosis of benign and malignant

osseous conditions. When combined SPECT/CT is used, the benefit

of precise anatomic localization of the radiotracer uptake and the

corresponding CT appearance may help clarify the nature of an

abnormality. Despite the increasing clinical usage and experience

during the last few years, the SPECT/CT features of many osseous

conditions have not been fully described and many nuclear

medicine physicians, radiologists and other physicians (like

orthopedic surgeons) are slowly becoming familiar with the

combined Bone Scintigraphy SPECT/CT patterns.

Our goal is to demonstrate different examples of benign and

malignant conditions on Tc99m-HDP SPECT/CT, focusing on the

additive value of this method and its correlation with clinical

information and other imaging modalities. We will use a variety of

cases collected in our institution, including, among others:

osteoarthritis, undifferentiated connective tissue disease, stress

fracture, temporo-mandibular joint disease, heterotopic ossification,

osteosarcoma, and spine hemangioma.

Case 3 – Facet Joint Disease

Case 1 – Osteoarthritis

Area of abnormal

osteoblastic activity.

Possible additional value of SPECT/CT

imaging:

Spine - posterior elements Differentiate among pars fracture, tumor, facet joint

arthritis, metastasis and osteophytes.

Spine – vertebral body Localize underlying bone abnormality: tumor,

compression fracture, discitis/osteomyelitis, etc.

Skull

Localize underlying bone abnormality: TMJ disease,

skull base fracture, otitis/mastoiditis, tumor, Paget’s

disease, etc.

Extremities

Delineate area of abnormal activity. Help to

differentiate trauma, tumor, DJD, arthritis, infection

or congenital abnormality.

Foot and Ankle

Identify stress fractures of the mid foot, DJD in the

mid foot and hind foot, tarsal coalition and

osteochondritis dissecans (OCD).

Soft tissues - Heterotopic

Ossification

Identify the soft tissue involved: e.g. areas of

heterotopic ossification. Plan surgical resection

when activity has resolved.

Orthopedic hardware

Identify failure of the surgical hardware: fracture of

the bone graft, formation of a pseudarthrosis,

hardware loosening; facet joint arthritis or disk

space degenerative disease at adjacent levels, or

findings, such as sacroiliitis, infection or pathology

associated with bone graft donor sites in the pelvis.

Key Points

•Bone Scintigraphy SPECT/CT has an additive value over whole

body scintigraphy and SPECT.

•SPECT/CT findings can help differentiate among bone pathologies

in several clinical scenarios, obviating extra imaging.

•Clinical information is key to interpret Bone SPECT/CT

scintigraphic findings correctly.

•Case: 73y/o male with severe neck pain, primary right sided and

worse with hyperextension.

•Findings: Severe osteoarthritis of the cervical spine, particularly C1-

C2 level. No osteoblastic involvement of the occiput-C1 joint.

•Additional value of SPECT/CT: Able to localize the areas of active

osteoarthritis and help in the surgical planning.

•Management: Patient underwent C1-T1 fusion.

Case 2 - Hemangioma

•Case: 79y/o female with a history of cauda equina paraganglioma,

post resection and L3-L5 laminectomy.

•Findings: Lytic lesion in the superior end-plate of L3 with intense

focal osteoblastic activity. Facet degenerative disease in the distal

lumbar spine.

•Additional value of SPECT/CT: Able to morphologic characterize

the area of abnormal activity. Exclude the possibility of osteophyte

or post surgical changes.

•Management: Biopsy proven Hemangioma. No evidence of

paraganglioma.

•Case: 57y/o female with osteoporosis and severe back pain. No history of trauma.

•Findings: Osteoarthritis of the L5-S1 facet joints, no fracture. Anterior beaking

osteophytes of L1-L2.

•Additional value of SPECT/CT: Able to exclude pathologic fracture of the

vertebral body and spondylolysis.

•Management: Patient underwent L5-S1 facet joint steroid injections with good

clinical response.

Case 4 – Heterotopic Ossification

•Case: 38y/o athlete male with history of trauma developed incapacitating leg and

hip pain.

•Findings: Severe osteoblastic activity in areas of heterotopic ossification involving

the left gluteus muscles and medial aspect of the left knee.

•Additional value of SPECT/CT: Localize the areas of active heterotopic ossification

and help in the surgical planning.

•Management: Initially treated with NSAIDS and then, surgery after improvement

of abnormal activity.

Case 5 – L3 Spondylolysis

•Case: 16y/o female with severe back pain, primary right sided and worse with

hyperextension.

•Findings: Levoscoliosis of the lumbar spine with focal activity in unilateral right

L3 spondylolysis.

•Additional value of SPECT/CT: Correctly diagnose the fracture and exclude

other causes of unilateral posterior elements activity.

•Management: Patient was placed on NSAIDS, physical rest and back brace.

Case 6 – Osteosarcoma

•Case: 50y/o female with osteosarcoma of the C2 vertebrae, post laminectomy,

posterior fusion and radiation.

•Findings: Persistent osteoblastic activity in an aggressive destructive lesion of

the C2 arch and odontoid. Linear activity along the posterior pedicle screws.

•Additional value of SPECT/CT: Localize recurrence and evaluate base of skull

extension.

•Management: Patient was started on chemotherapy, but developed lung

metastasis afterwards.

Case 7 – Fibrous Dysplasia

•Case: 45y/o female with dizziness and headache.

•Findings: Sclerotic ground glass osteoblastic active lesion in the clivus.

•Additional value of SPECT/CT: Localize the lesion and exclude other pathology.

•Management: Follow up imaging showed stable findings suggestive of Fibrous

Dysplasia.

Case 8 – TMJ disease

•Case: 58y/o female with neck pain and headache.

•Findings: Intense ostoblastic activity in the left temporal mandibular joint (TMJ)

with sclerosis of mandibular condyle and temporal fossa. Mild DJD of the upper

cervical spine (not shown).

•Additional value of SPECT/CT: Identify extra focus of abnormal osteoblastic

activity, in this case the TMJ.

•Management: Patient was treated with NSAIDS and night occlusal splints with

improvement of the pain.

Contact email: fpaes@med.miami.edu

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