CASE OF THE WEEK – “A case of bilateral charcot joints of foot (right >>left) with right mid foot ulceration and planter surface soft tissue inflammation.” by Dr Shekhar Shikare, HOD & Consultant, Nuclear Medicine, NMC Royal Hospital Sharjah

CASE OF THE WEEK – “A case of bilateral charcot joints of foot (right >>left) with right mid foot ulceration and planter surface soft tissue inflammation.” by Dr Shekhar Shikare, HOD & Consultant, Nuclear Medicine, NMC Royal Hospital Sharjah

The role of SPECT/CT hybrid imaging in the Charcot foot

Charcot arthropathy is a complex condition affecting diabetic patients with neuropathy. Diagnosis of acute Charcot arthropathy particularly in absence of any perceptible trauma is very challenging as clinically it can mimic osteomyelitis and cellulitis. Delay in recognition of Charcot arthropathy can result in gross instability of foot and ankle. Early diagnosis can provide an opportunity to halt the progression of disease.

Charcot neuroarthropathy (CN) is a serious complication of diabetes mellitus that can cause major morbidity including limb amputation. Since it was first described in 1883, and attributed to diabetes mellitus in 1936, the diagnosis of CN has been very challenging even for the experienced practitioners. Imaging plays a central role in the early and accurate diagnosis of CN, and in distinction of CN from osteomyelitis. Conventional radiography, computed tomography, nuclear medicine scintigraphy, magnetic resonance imaging, and positron emission tomography are the imaging techniques currently in use for the evaluation of CN but modalities other than magnetic resonance imaging appeared to be complementary. This study focuses on imaging findings of acute and chronic neuropathic osteoarthropathy in diabetes and discrimination of infected vs. non-infected neuropathic osteoarthropathy.

Keywords:diabetes mellitus, complications, diabetic foot, Charcot foot, diagnostic imaging

Today diabetic polyneuropathy is the most common cause of neuropathic osteoarthropathy in developed countries. After Jordan et al. has first described the association between Charcot neuroarthropathy (CN) and diabetes. CN has been referred for the specific form of neuropathic arthropathy. Clinical presentation of diabetic osteomyelitis and acute CN is similar. Furthermore, osteomyelitis and CN can co-exist in the same extremity. All of these factors pose in a diagnostic dilemma, but the imaging plays a pivotal role in arriving at the definitive diagnosis and adequate treatment.

The majority of the patients with CN present between the fifth and sixth decades and most have had diabetes mellitus for a minimum of 10 years. The risk of CN development is not related to the type of diabetes. Of all patients with diabetes, 0.1–7.5% have CN and 29% of diabetics with peripheral neuropathy have CN. The reported incidence of bilateral involvement varied between 9 and 75%. Diabetic CN almost exclusively affects the foot and ankle, other locations being extremely rare. It commonly presents in the midfoot, but it may also occur in the forefoot and hindfoot.

Diabetic CN has been classified with a variety of classification systems. These systems added the benefit of predicting outcome and prognosis. The most commonly used anatomic system is described by Sanders and Frykberg . Pattern 1 involves the phalanges, interphalangeal and the metatarsophalangeal joints; pattern 2 the tarsometatarsal; pattern 3 the cuneonavicular, talonavicular, and calcaneocuboid articulations; pattern 4 the talocrural joint and pattern 5 involves the posterior calcaneus (Fig. 1). Studies have shown that patterns 2 and 3 are the most common, with approximately 45% of cases are pattern 2 and 35% are pattern 3.

Illustration of Sanders and Frykberg's classification of CN. Pattern I: phalanges, interphalangeal and the metatarsophalangeal joints; pattern II: the tarsometatarsal joints; pattern III: the cuneonavicular, talonavicular, and calcaneocuboid articulations; pattern IV: the talocrural joint; pattern V: the posterior calcaneal involvement.

CASE

61-year-old gentle man with a history of diabetes (one year), presented with swollen right foot with mid foot skin ulceration six-month duration. Underwent detriment of the right foot ulcer and showing healing pattern.

Referred for 99mTc MDP whole body bone and SPECT-CT imaging with ? right foot osteomyelitis based on the MRI findings

99m Tc-MDP Bone & hybrid SPECT CT images of foot

BLOOD FLOW AND BLOOD POOL IMAGES OF FOOT

It shows abnormally increased blood flow and pooling of tracer seen in planter surface of the right foot (distal 2/3rd). In addition to this there is abnormal pooling of tracer seen in left mid foot region (figure 2 &3)

A case of bilateral charcot joints of foot (right to left) with right mid foot ulceration and planter surface soft tissue inflammation 02

BLOOD FLOW IMAGES OF RIGHT FOOT


A case of bilateral charcot joints of foot (right to left) with right mid foot ulceration and planter surface soft tissue inflammation 03

BLOOD POOL AND BONE IMAGES OF FOOT

A case of bilateral charcot joints of foot (right to left) with right mid foot ulceration and planter surface soft tissue inflammation 04 A case of bilateral charcot joints of foot (right to left) with right mid foot ulceration and planter surface soft tissue inflammation 05 A case of bilateral charcot joints of foot (right to left) with right mid foot ulceration and planter surface soft tissue inflammation 06 A case of bilateral charcot joints of foot (right to left) with right mid foot ulceration and planter surface soft tissue inflammation 07 A case of bilateral charcot joints of foot (right to left) with right mid foot ulceration and planter surface soft tissue inflammation 08 A case of bilateral charcot joints of foot (right to left) with right mid foot ulceration and planter surface soft tissue inflammation 09

RIGHT FOOT HYBRID SPECT CT IMAGES

Right foot shows abnormally increased tracer uptakes in mid foot bones (including cuboid, navicular, and cuneiforms) along with portion of talus, head of 1st metatarsal bone, lateral and medial malleolus of tibia and fibula, lower end of tibia subarticular region, anterior part of lower end tibia, posterior aspect of calcaneum (possibly to be due to planter fasciitis).

Articulation of hind and mid foot, talo-navicular, calcaneo-cuboid, intertarsal articulation, tarso-metatarsal articulations, tibio fibular articulation and anterior part of lower tibia (figure 4 to 9)

Underlying CT images of right foot -Extensive involvement of the mid foot bones, which shows lytic and sclerotic destruction with disorganization. To lesser extent anterior portion of talus & calcaneus is involved and showing lytic and destructive pattern. Forefoot is uninvolved. Bone density is preserved.

Soft tissue component, which is involving intrinsic musculature of the foot on plater aspect with air pocket and also involvement of overlying subcutaneous tissue and at deep ulcer on the planter aspect.

RIGHT FOOT HYBRID SPECT CT FINDINGS FAVOURS PREDOMINANLTLY MID FOOT & TO SOME EXTENT HIND FOOT CHARCOTS OSTEOARTHOPATHY WITH UNDERLYING SOFT TISSE INFLAMMATION (figure 2 to 9)

LEFT FOOT HYBRID SPECT CT IMAGES

Left foot shows abnormally increased tracer uptakes in mid foot bones (All the three cuneiforms bones). 

Underlying CT images of left foot- Involvement of mid foot bones with lytic & destructive lesions to lesser extent. No soft tissue involvement is seen.

A case of bilateral charcot joints of foot (right to left) with right mid foot ulceration and planter surface soft tissue inflammation 10 A case of bilateral charcot joints of foot (right to left) with right mid foot ulceration and planter surface soft tissue inflammation 11 A case of bilateral charcot joints of foot (right to left) with right mid foot ulceration and planter surface soft tissue inflammation 12

LEFT FOOT HYBRID SPECT CT FINDINGS FAVOURS EARLY MID FOOT CHARCOTS OSTEOARTHOPATHY ( figure 2,3,10,11 & 12).

Subsequently patient underwent surgical intervention of the right foot and found to have soft tissue inflammation without any osteomyelitis of right foot bones.

Discussion

Charcot arthropathy is a complex condition affecting diabetic patients with neuropathy. Diagnosis of acute Charcot arthropathy particularly in absence of any perceptible trauma is very challenging as clinically it can mimic osteomyelitis and cellulitis. Delay in recognition of Charcot arthropathy can result in gross instability of foot and ankle. Early diagnosis can provide an opportunity to halt the progression of disease.

MRI has an integral role to play in the radiological diagnosis of CN and associated infectious conditions.

A variety of radionuclide studies have been used in CN. The technetium-99m methylene diphosphonate (Tc-MDP) bone scan is clinically useful in detecting and localizing abnormal bone, with high accuracy levels. Hybrid SPECT/ CT is of crucial importance in the diabetic foot, where there may be a muted response to trauma and ill-defined symptomatology. It should be noted that the Charcot feet presented in these cases were early with very few of the classically described changes. The hybrid technique is recommended to enhance the accuracy of assessing Charcot disease in its active phase.

In complicated cases in which there is an increased bone turnover (i.e. infection, trauma, surgery), A bone scan is less useful than leukocyte/colloid scintigraphy. There is enrichment on the bone scan in both conditions, whereas leukocyte/colloid scintigraphy is only positive in osteomyelitis.

There is currently no definitive cure for diabetes or for the associated arthropathy, and the management is based on the prevention and treatment of complications. The early recognition of a diabetic, or Charcot, arthropathy is essential for a satisfactory outcome.