CASE OF THE WEEK – “Hybrid Bone SPECT/CT imaging of the Foot and Ankle: Potential Clinical Applications in Foot Pain” by Dr ShekharShikare, HOD & Consultant, Nuclear Medicine, NMC Royal Hospital Sharjah

Hybrid Bone SPECT/CT imaging of the Foot and Ankle: Potential Clinical Applications in Foot Pain

The complex anatomy and function of the foot and ankle can make it difficult to determine the cause of symptoms (origin of the pain) in patients with foot and ankle pathology. Following initial clinical and radiographic assessment, additional imaging with magnetic resonance imaging may be required, which is often seen as the modality of choice because of the excellent visualization of bone and soft tissues. Although sensitive to pathological changes in bone metabolism and vascularity, technetium-99m (Tc-99m) bone scintigraphy often lacks the specificity and resolution required to evaluate the structures of the foot and ankle. Tc-99m methylene diphosphonate single-photon emission computed tomography/computed tomography (SPECT/CT) combines this sensitivity with the superior anatomical detail of CT, enabling better localization of pathological uptake and evaluation of associated structural changes. As a result, SPECT/CT has been growing in popularity for the assessment of patients with chronic pain symptoms that are insufficiently explained by clinical findings and conventional imaging. These include locating active sites of osteoarthritis, coalitions, osteoid osteoma, occult stress fractures, tendinitis, plantar fasciitis, and impingement syndromes etc. where it can provide additional information that may change the initial diagnosis and subsequent management plan. Studies have reported modification of the surgical approach and site of intra-articular local anesthetic injections following SPECT/CT with good results.

Applications of HYBRID BONE SPECT/CT

Osteoarthritis

Osteoarthritis of the foot and ankle are common conditions, and the clinical significance of tarsal tracer uptakes in particular mid-foot problems appear good targets for hybrid bone SPECT/CT imaging. Also, evaluation of degenerative changes in the distal tibiofibular syndesmosis complex after trauma has improved with the introduction of bone SPECT/CT.

In addition, the technique can be of use to guide the optimal site for intra-articular infiltrations. Finally, literature data supports the use of bone SPECT/CT when pain recurs after arthroplasty or arthrodesis for degenerative joint disease.

Osteochondral lesions

In osteochondral lesions, SPECT/CT can contribute valuable information in addition to MRI on the extent of the lesion, on determining the most active lesion in case of multifocal disease, and on selecting patients for surgical intervention.

Insufficiency fracture

The typical bone SPECT/CT pattern of insufficiency fractures consists of increased focal or linear uptake on SPECT, no apparent changes or discrete fracture lines on CT, and MRI findings ranging from moderate periosteal edema on STIR images, to marrow changes on T2 and later T1 images, up to a visible fracture line.

Post-traumatic injuries

Persisting pain after ankle inversion injuries is common and causes include undetected syndesmotic sprain, talar osteochondral lesions, and stress fractures, all of which can be diagnosed using bone SPECT/CT. Syndesmotic sprain presents as increased tracer uptake in the posterior tibial region and interosseous membrane on delayed phase images, while changes on plain radiographs and CT can be subtle. Similarly, talar osteochondral lesion demonstrate increased subarticular uptake that can also involve the entire posterior half of the talus.

Tarsal coalition

Tarsal coalitions are congenital anomalies consisting of complete or partial unions between two or more bones of the midfoot or hindfoot. Patients typically present with foot pain in adolescence. Most coalitions occur in the calcaneo-navicular (45%) or talocalcaneal (45%) joint. SPECT/CT is very helpful in the assessment of the fusion type (bony, cartilaginous, or fibrous coalition) and the grade of scintigraphy activity.

Ankylosing spondylitis

Ankle pain may be the harbinger of systemic inflammatory diseases such as ankylosing spondylitis. Focally increased uptake in the talocalcaneal joints correlating on CT with partial ankylosis with or without subchondral sclerosis can provide important clues for a broader systemic disease etiology.

Plantar fasciitis

The typical scintigraphy pattern consists of increased uptake in the medial calcaneal tubercle correlating with a spur on CT (Fig. 6c). While it often presents as an isolated condition, it can also be associated with ankylosing spondylitis.

Tendinopathies

Posterior tibial tendon dysfunction (PTTD) is characterized by pain and swelling over the course of the tendon at the level of the medial malleolus and navicular insertion. It can be an overuse injury in runners caused by repetitive trauma inducing an inflammatory response. Flow and blood pool images show increased uptake along the tendon and medial malleolus, extending to the navicular. Another frequent cause of posterior foot pain is Achilles tendon injury.

Accessory ossicles (Navicular syndrome)

There are many possible accessory ossicles of the feet and while most often asymptomatic, they can be associated with pain and increased uptake on bone SPECT/CT.

Tophaceous gout

Caused by urate deposition, tophi are soft tissue nodules which appear in periarticular soft tissues and occur together with bone erosions with sclerotic margins producing typical punched-out lesions with overhanging cortical edges. Unlike other arthropathies such as rheumatoid arthritis, joint space and bone mineral density are well preserved until late in the disease course. Of note, differential diagnosis with tumoral calcinosis is possible because urate crystals do not exhibit tracer uptake in contrast to calcium deposits.

Illustration of Hybrid bone SPECT/CT applications in imaging the painful foot and ankle.

Case 1

Osteoarthritis of metatarso-phalangeal joint of 1st big toe on both sides and left Achilles tendinitis.

Hybrid Bone SPECT/CT imaging of the Foot and Ankle: Potential Clinical Applications in Foot Pain by Dr Shekar Shikare, HOD & Consultant, Nuclear Medicine, NMC Royal Hospital Sharjah Hybrid Bone SPECT/CT imaging of the Foot and Ankle: Potential Clinical Applications in Foot Pain by Dr Shekar Shikare, HOD & Consultant, Nuclear Medicine, NMC Royal Hospital Sharjah

Hybrid bone SPECT-CT images of foot shows abnormally increased tracer uptakes in both metatarsal- phalangeal joints of big toe and focally increased tracer uptakes at the insertion of the tendon.

Case 2

Active osteoarthritis of right talo-navicular articulation

Hybrid Bone SPECT/CT imaging of the Foot and Ankle: Potential Clinical Applications in Foot Pain by Dr Shekar Shikare, HOD & Consultant, Nuclear Medicine, NMC Royal Hospital Sharjah Hybrid Bone SPECT/CT imaging of the Foot and Ankle: Potential Clinical Applications in Foot Pain by Dr Shekar Shikare, HOD & Consultant, Nuclear Medicine, NMC Royal Hospital Sharjah

Hybrid bone SPECT-CT images of foot shows abnormally increased tracer uptakes in right talo-navicular articulation.

Case 3

Active osteoarthritis of left talo-navicular articulation

Hybrid Bone SPECT/CT imaging of the Foot and Ankle: Potential Clinical Applications in Foot Pain by Dr Shekar Shikare, HOD & Consultant, Nuclear Medicine, NMC Royal Hospital Sharjah Hybrid Bone SPECT/CT imaging of the Foot and Ankle: Potential Clinical Applications in Foot Pain by Dr Shekar Shikare, HOD & Consultant, Nuclear Medicine, NMC Royal Hospital Sharjah

Hybrid bone SPECT-CT images of foot shows abnormally increased tracer uptakes in left talo-navicular articulation.

Case 4

Left Achilles tendinitis /Enthesopathy

Hybrid Bone SPECT/CT imaging of the Foot and Ankle: Potential Clinical Applications in Foot Pain by Dr Shekar Shikare, HOD & Consultant, Nuclear Medicine, NMC Royal Hospital Sharjah

Hybrid bone SPECT-CT images of foot shows abnormally increased tracer uptakes in left calcaneal bone posteriorly suggestive of left Achilles tendinitis /Enthesopathy.

Case 5

Accessory navicular syndrome

Hybrid Bone SPECT/CT imaging of the Foot and Ankle: Potential Clinical Applications in Foot Pain by Dr Shekar Shikare, HOD & Consultant, Nuclear Medicine, NMC Royal Hospital Sharjah Hybrid Bone SPECT/CT imaging of the Foot and Ankle: Potential Clinical Applications in Foot Pain by Dr Shekar Shikare, HOD & Consultant, Nuclear Medicine, NMC Royal Hospital Sharjah Hybrid Bone SPECT/CT imaging of the Foot and Ankle: Potential Clinical Applications in Foot Pain by Dr Shekar Shikare, HOD & Consultant, Nuclear Medicine, NMC Royal Hospital Sharjah

Hybrid Bone SPECT/CT fused images show focally increased tracer uptake tracer uptakes in the adjoining region of Type II accessory navicular bones & navicular bone of the LEFT FOOT favoring accessory navicular syndrome. While in asymptomatic RIGHT FOOT, there is minimal to mildly increased tracer uptakes in the adjoining region of Type II accessory navicular bones & navicular bone favoring quiescent pattern.

Case 6

Plantar fasciitis

Hybrid Bone SPECT/CT imaging of the Foot and Ankle: Potential Clinical Applications in Foot Pain by Dr Shekar Shikare, HOD & Consultant, Nuclear Medicine, NMC Royal Hospital Sharjah Hybrid Bone SPECT/CT imaging of the Foot and Ankle: Potential Clinical Applications in Foot Pain by Dr Shekar Shikare, HOD & Consultant, Nuclear Medicine, NMC Royal Hospital Sharjah

Hybrid bone SPECT-CT images of foot shows abnormally increased tracer uptakes in inferior part of the tuberosity of the right calcaneal bone suggesting active planter fascitis.

Case 7

Post-traumatic injuries

Hybrid Bone SPECT/CT imaging of the Foot and Ankle: Potential Clinical Applications in Foot Pain by Dr Shekar Shikare, HOD & Consultant, Nuclear Medicine, NMC Royal Hospital Sharjah

Hybrid bone SPECT-CT images of foot shows abnormally increased tracer uptakes in right talo-calcaneal articulation favors active osteoarthritis.

MRI right ankle- Osteoarthritic changes at the medial compartment of the sub-talar joint (old trauma sequelae).

Case 8

Post-traumatic injuries

Hybrid Bone SPECT/CT imaging of the Foot and Ankle: Potential Clinical Applications in Foot Pain by Dr Shekar Shikare, HOD & Consultant, Nuclear Medicine, NMC Royal Hospital Sharjah Hybrid Bone SPECT/CT imaging of the Foot and Ankle: Potential Clinical Applications in Foot Pain by Dr Shekar Shikare, HOD & Consultant, Nuclear Medicine, NMC Royal Hospital Sharjah Hybrid Bone SPECT/CT imaging of the Foot and Ankle: Potential Clinical Applications in Foot Pain by Dr Shekar Shikare, HOD & Consultant, Nuclear Medicine, NMC Royal Hospital Sharjah Hybrid Bone SPECT/CT imaging of the Foot and Ankle: Potential Clinical Applications in Foot Pain by Dr Shekar Shikare, HOD & Consultant, Nuclear Medicine, NMC Royal Hospital Sharjah

Hybrid bone SPECT-CT images of foot shows small focally active abnormality seen at syndesmosis level of right fibular bone, favors stress fracture.

 

MRI right ankle- focal sprain involving lateral fibers of inter-malleolar ligament with minimal focal sprain of the posterior talo-fibular ligament. Minimal focal sprain of tibio-talar component of the deltoid ligaments.

Case 9

Bone Cyst with Sclerosis

Hybrid Bone SPECT/CT imaging of the Foot and Ankle: Potential Clinical Applications in Foot Pain by Dr Shekar Shikare, HOD & Consultant, Nuclear Medicine, NMC Royal Hospital Sharjah Hybrid Bone SPECT/CT imaging of the Foot and Ankle: Potential Clinical Applications in Foot Pain by Dr Shekar Shikare, HOD & Consultant, Nuclear Medicine, NMC Royal Hospital Sharjah Hybrid Bone SPECT/CT imaging of the Foot and Ankle: Potential Clinical Applications in Foot Pain by Dr Shekar Shikare, HOD & Consultant, Nuclear Medicine, NMC Royal Hospital Sharjah Hybrid Bone SPECT/CT imaging of the Foot and Ankle: Potential Clinical Applications in Foot Pain by Dr Shekar Shikare, HOD & Consultant, Nuclear Medicine, NMC Royal Hospital Sharjah Hybrid Bone SPECT/CT imaging of the Foot and Ankle: Potential Clinical Applications in Foot Pain by Dr Shekar Shikare, HOD & Consultant, Nuclear Medicine, NMC Royal Hospital Sharjah Hybrid Bone SPECT/CT imaging of the Foot and Ankle: Potential Clinical Applications in Foot Pain by Dr Shekar Shikare, HOD & Consultant, Nuclear Medicine, NMC Royal Hospital Sharjah

Hybrid bone SPECT-CT images of foot shows active abnormality in right navicular bone which is corresponding with underlying cyst with sclerotic margins.

 

Conclusion

These cases aim to highlight the advantages of Hybrid Bone SPECT/CT, potential applications and explain the imaging appearances of common pathologies that may be observed.

Hybrid Bone SPECT/CT can be an effective problem-solving tool in patients in patients with foot pain, when careful history taking, clinical examination, and first-line imaging modalities fail to identify the underlying cause.