CASE REPORT 
Annals of Nuclear Medicine Vol. 14. No 1. 53-55, 2000 

Demonstration of Achilles tendon rupture by three phase bone scintigraphy and MRI 

Wei-Jen SHIH and Calixto PULMANO 
Nuclear Medicine Service and Rediology Service, VA Medical Center, and Division of Nuclear Medicine, Department of Diagnostic Radiology, University of Kentuckty Medical Center, KY, USA
 
A man with complaint of soreness in the right medial ankle underwent three-phase bone scintigraphy; the results of the study suggested chronic active osteomyelitis or cellulitis, he was on antibiotics and was not experiencing any improvement. MR imaging confirmed Achilles tendon rupture. This case illustrates that a positive three-phase study Is non-specific disease entity. 

Key words: three-phase bone scintigraphy, MR imaging, Achilles tendon rupture

REPORT OF A CASE 
A 63-yr-old man with a history of hypertension, coronary artery heart disease, carotid stenosis, and cardiovascular accident complained of sores in the right medial ankle for about one year. He had a previous medial malleolus ulcer on his right leg, which had healed; but he had also had chronic swelling and pain of the left leg. On physical examination, there was a 0.5-1 cm dark scab with 2-mm erythema surrounding it in the medial aspect of the right ankle. CBC revealed WBC 5.7 k/cmm (n = 5-10), RBC 4.1 m/cmm (n = 4.6-6.2), HGB 12.4 g/dl (n = 14-18), PLT 122 k/cmm (n = 150-450); initial ESR was 6 mm/hr (n = 0-20) and became 23 mm/hr. Because of suspected chronic active osteomyelitis, the patient underwent three-phase bone scintigraphy: Rapid sequential imaging every 5 seconds of both legs showed increased radioactivity in the lower end of the right leg (Fig. 1A). The blood pool image showed increased uptake in the lower two-thirds of the right tibia with a focal area of increased uptake in the end of the right tibia (Fig. IA). Two-hour posterior image showed diffusely increased uptake in the right knee, lower leg, and right foot especially in the right ankle region (Fig. 1B). Two-hour anterior images of both lower extremities showed mild and diffuse uptake in the soft tissue in the right leg, especially at the end of the right tibia. These findings were consistent with chronic active osteomyelitis or cellulitis (Fig. 1C). The patient was placed on antibiotics. Despite the use of antibiotics, his left leg pain did not improve. Then he was referred for orthopedic consultation. Radiographic examination of the left foot and the left leg showed no bone erosion. MRI with T-2 weighted fat saturated sagittal section at the level of the right distal leg and ankle three months after the bone scintigraphy showed fluid collection in the site of retracted Achilles tendon and gastrocnemius muscle (Fig. 2A). MRI with T-1 weighted sagittal section at the level of the right distal leg and ankle showed absent tendon; discontinuity or disruption and retraction of the proximal tendon segment is seen (Fig. 2B). MRI with T-2 weighted transaxial section at the level of the right distal leg and ankle showed fluid collection (Fig. 2C). These findings are consistent with rupture of the right Achilles tendon just above its insertion into the os calcis and retraction of the tendon and gastrocnemius. 

Received August 16, 1999, revision accepted November 25, 1999. For reprint contact: Wei-Jen Shih, M.D., Nuclear Medicine Service, VA Medical Center, Lexington KY 40501 , USA. E-mail: wshihO@pop.uky.edu 

DISCUSSION 
Three-phase bone scintigraphy is sensitive and specific for osteomyelitis 1 ; Schauwecker reported that sensitivity was 94% and specificity was 95%.2 Despite of this, it is some time non-specific; three-phase bone scintigraphy might be positive in non-inflammatory bone disease such as giant cell tumor 3 synovial sarcoma 3 sarcoma.4 gouty arthritis 3,5 and Reiter's syndrome. 3.6 Also it might be positive with bone scintigraphy included in stress fractures,7,8 non-union fracture 9 Infarction lo and traumatic myositis.11 In our case the focal area of increase up-take in the distal right leg on the three-phase bone study might reflect locally inflammatory reaction secondary to ruptured Achilles tendon that was responsible for the positive three-phase bone study. In comparison with left lower extremity, diffusely increased radioactivity in the right knee, soft tissue of the right leg, and right foot, as shown on the Figures IB and IC, might be explained by sympathetic reflect dystrophy. Because this patient had suffered from a standing right ankle pain. MR imaging provides a great potential in the evaluation of tendon, because of its excellent differentiation of tendons from surrounding inflammatory changes, hematoma, fluid collection in the ankle; and MR is well suited to image patients with suspected Achilles tendon rupture.12 Thus. MR imaging is an excellent method for revealing a rupture and confirming the diagnosis, 13 

ACKNOWLEDGMENT 
We appreciate Barbara Circle RT, MR For her MRI technical assistance.
 
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