Calf “Arch Sign” Seen on a Tc-99m-MDP Bone Scan Is Indicative of Synovial Fluid Leak in Ruptured Baker's Cysts: Case Reports and Analysis of Literature / 대한핵의학회잡지

The authors present two cases in which the ruptured popliteal (Baker's) cysts remained undetected and were diagnosed only during an isotope investigation. The aim was to describe a specific imaging sign, the “arch sign”, that is indicative of ruptured Baker's cysts. In both cases, the whole-body imaging was performed 2 hours after injection of 706.7 MBq of Tc-99m-MDP. Single-photon emission computed tomography (SPECT) imaging was performed to localize an accumulation of the radiopharmaceutical. An analysis of literature was performed to connect these cases with previously reported data and to detect the pathognomonic radio image sign of ruptured popliteal cysts. The arch-shaped distribution of the radiopharmaceutical below the knee joints was seen already on the whole-body bone scan image in both cases. An anterior view of SPECT MIP images showed the arched accumulation of the Tc-99m-MDP bone tracer along the postero-medial aspect of the right calf secondary to synovial fluid leak from a ruptured Baker's cyst. The similar arthroscintigrams were published since 1971 without recognizing this sign as pathognomonic. Tc-99m-MDP bone scanning is sensitive for a Baker's cyst with synovial effusion, and distribution of a radiopharmaceutical in the medial posterior calf in a shape of an arch, the arch sign, may serve as an indicator of a ruptured popliteal cyst.

Focal Increased Tc-99m MDP Uptake in the Nutrient Foramen of the Femoral Diaphysis on Bone SPECT/CT / 대한핵의학회잡지

We present images of an 83-year-old female with a history of osteoporosis and bilateral total knee replacement arthroplasty, referred for bone scintigraphy and single-photon emission computed tomography (SPECT)/computed tomography (CT), owing to left knee pain. No trauma to, or intense exercise of, the kneewas reported. The bone scan and SPECT/CT revealed a focally increased Tc-99m methylene diphosphonate (MDP) uptake in the medial cortex of the left femoral diaphysis with matched linear radiolucency on CT images. This was misinterpreted as atypical femoral stress fracture; however, focal stress reaction injury to the nutrient foramen was confirmed on contrast-enhanced magnetic resonance imaging.

Clinical Study on Early Diagnosis of Skeletal Disorders by Bone Scan with Tc-99m-MDP (Medronate) / 대한정형외과학회잡지

Early detection of skeletal disorders was very important role in establishing therapeutic modality and prevention of complications. Since Tc-99m-phosphates derivatives used in bone scan agent, remarkable improvement was noted in effectiveness, cost, radiation hazard to patient and image quality than previously used agents such as strontium or fluoride. Bone scan with Tc-99m-MDP was done in 155 cases for early diagnosis of skeletal disorders at Severance Hospital, College of Medicine, Yonsei University from August, 1980 to May, 1982 were analyzed both clinically and radiologically, and the following results were obtained. l. Among 19 cases of avascular necrosis, positive cases were 17 (89.5%) in bone scan and 6(31.6%) in X-ray. Positive pattern could be classified into 3 types and the radionuclide uptake in the femoral head was decreased in 3 cases which was negative in X-ray and duration of their symptoms was within 4 months. 2. Fifteen among 17 hip fractures or dislocations were positive in bone scan. In 12 (80.0%) among 15 cases, complications were revealed and positive cases in X-ray were 7(58.3%), which were all positive in bone scan. 3. In 20 bone scans for early diagnosis of acute osteomyelitis, positive in bone scan were 17 and 14 (82.4%) of 17 cases were finally diagnosed as acute osteomyelitis. Among 15 cases diagnosed as acute osteomyelitis, positive in X-ray were 8(53.3%) and sensitivity of acute osteomyelitis in bone scan was 93.3%. 4. In 25 cases of the suspected infection of the joint, 15 were positive in bone scan and among them, cases diagnosed as pyogenic arthritis were 12 (80.0%) and positive in X-ray were 2 (16.7%). Only one of 10 cases of transient synovitis of the hip joint was positive in bone scan. 5. In rheumatoid arthritis, 13 of 15 cases were positive in bone scan and 10 among them were revealed the diffuse uptake of the radionuclide in the joint. In degenerative arthritis, 7 of 8 cases were positive in bone scan and they were revealed the focal uptake of the radionuclide in the same site where the bone was changed in x-ray. 6. Among 28 cases showed spine fracture in X-ray after trauma, 15 (53.6%) were positive in bone scan. In spine fracture, it was difficult to differentiate fresh fracture from old fracture with bone scan. The positive duration of bone scen in fracture of weight bearing bone was longer than in spine fracture. Rib fracture which was not found in X-ray could be diagnosed with bone scan.