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.
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The authors thank Michael Shterenshis for editing assistance.
Compliance with Ethical Standards
Conflict of Interest
Haim Golan and Evgeniya Fridburg declare that they have no conflict of interest.
The research did not involve human participants and/or animals because only images and previously obtained data from the charts were analyzed. No personal details of patients appear in the article as in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
The institutional review board of our institute approved this retrospective study, and the requirement to obtain informed consent was waived.
Labropoulos N, Shifrin DA, Paxinos O. New insights into the development of popliteal cysts. Br J Surg. 2004;91:1313–8.CrossRefGoogle Scholar
Levin MH, Nordyke RA, Ball JJ. Demonstration of dissecting popliteal cysts by joint scans after intra-articular isotope injections. Arthritis Rheum. 1971;14:591–8.CrossRefGoogle Scholar
Lin WY, Wang SJ. Rupture of a popliteal cyst visualized by radionuclide venography and confirmed by radionuclide arthrography. Clin Nucl Med. 1997;22:326.CrossRefGoogle Scholar
Torreggiani WC, Al-Ismail K, Munk PL, Roche C, Keogh C, Nicolaou S, et al. The imaging spectrum of Baker’s (popliteal) cysts. Clin Radiol. 2002;57:681–91.CrossRefGoogle Scholar
Shah A, James SL, Davies AM, Botchu R. A diagnostic approach to popliteal fossa masses. Clin Radiol. 2017;72:323–37.CrossRefGoogle Scholar
Mollá Olmos E, Martí-Bonmatí L, Llombart Aís R, Dosdá Muñoz R. Prevalence and characteristics of complications of Baker cysts by MRI. Rev Clin Esp. 2001;201:179–83.CrossRefGoogle Scholar
Macfarlane DG, Bacon PA. Popliteal cyst rupture in normal knee joints. Br Med J. 1980;281(6249):1203–4.CrossRefGoogle Scholar
Watkins AE, Poulose KP, Reba RC. Arthroscintigraphy with technetium albumin in diagnosis of pseudophlebitis (Baker’s) cyst. Br Med J. 1975;4:86.CrossRefGoogle Scholar
Chatzopoulos D, Markou P, Iakovou I. Scintigraphic imaging of knee synovitis in osteoarthritis after intra-articular injection of technetium-99m pertechnetate in the unilateral knee. Hell J Nucl Med. 2006;9:69–71.PubMedGoogle Scholar
Ushiyama T, Kawasaki T, Matsusue Y. Anterior tibial compartment syndrome following rupture of a popliteal cyst. Mod Rheumatol. 2003;13:189–90.CrossRefGoogle Scholar
Abdelrahman MH, Tubeishat S, Hammoudeh M. Proximal dissection and rupture of a popliteal cyst: a case report. Case Rep Radiol. 2012;2012:292414.PubMedPubMedCentralGoogle Scholar
Sato O, Kondoh K, Iyori K, Kimura H. Midcalf ultrasonography for the diagnosis of ruptured Baker’s cysts. Surg Today. 2001;31:410–3.CrossRefGoogle Scholar
Smith T, Shawe DJ, Crawley JC, Gumpel JM. Use of single photon emission computed tomography (SPECT) to study the distribution of 90Y in patients with Baker's cysts and persistent synovitis of the knee. Ann Rheum Dis. 1988;47:553–8.CrossRefGoogle Scholar