Abstract
We retrospectively studied the frequency of persistent foci of fat signal on magnetic resonance (MR) imaging in osteomyelitis to assess its frequency, cause and diagnostic value. The radiographs and MR scans of 100 patients with a final diagnosis of osteomyelitis referred to a specialist orthopaedic oncology service with the presumptive diagnosis of a bone tumour were reviewed. The MR signal and morphological characteristics were recorded with particular attention to the presence of persistent fat signal within the infected area, which was classified as diffuse or focal. Seventeen cases were classified on radiographic grounds as acute, 63 as subacute and 20 as chronic osteomyelitis. In the acute group 12 (70%) showed replacement of the marrow with fluid containing residual fatty signal, diffuse in seven and focal in five cases. Two cases showed predominantly fatty marrow with very early marrow oedema and three cases (18%) showed replacement of marrow fat with fluid and no residual fatty foci. None of the subacute group showed foci of fatty signal and two cases of inactive sclerosing osyeomyelitis in the chronic group showed restoration of normal marrow. Persistent fatty signal within the bone as well as soft tissues on MR imaging is a frequent finding in acute osteomyelitis. Radiological–pathological correlation suggests that the increasing intramedullary pressure leads to septic necrosis with death of the lipocytes and release of free fatty globules. This characteristic, but not pathognomonic, MR finding supports the diagnosis of osteomyelitis and may help to exclude the presence of a tumour.
Similar content being viewed by others
References
Fletcher BD, Scoles PV, Nelson AD (1984) Osteomyelitis in children: detection by magnetic resonance. Radiology 150:57–60
Beltran J, Noto AM, McGhee RB, Freedy RM, McCalla MS (1987) Infections of the musculoskeletal system: high-field strength MR imaging. Radiology 164:449–454
Tang JSH, Gold RH, Bassett LW, Seeger LL (1988) Musculoskeletal infection of the extremities: evaluation with MR imaging. Radiology 166:205–209
Unger E, Moldofsky P, Gatenby B et al (1988) Diagnosis of osteomyelitis by MR imaging. Am J Roentgenol 150:605–610
Erdman WA, Tamburro F, Jayson HT, Weatherall PT, Bond LB, Peshock RM (1991) Osteomyelitis: characteristics and pitfalls with MR imaging. Radiology 180:533–539
Tehranzadeh J, Wang F, Mesgarzadeh M (1992) Magnetic resonance imaging of osteomyelitis. Crit Rev Diagn Imaging 33:495–534
Gylys-Morin VM (1998) MR imaging of pediatric musculoskeletal inflammatory and infectious disorders. Clin North Am 6:537–559
Tehranzadeh J, Wong E, Wang F, Sadighpour M (2001) Imaging of osteomyelitis in the mature skeleton. Radiol Clin North Am 39:223–250
Gledhill RB (1973) Subacute osteomyelitis in children. Clin Ortop 96:57–69
Roberts JM, Drummond DS, Breed AL, Chesney J (1982) Subacute hematogenous osteomyelitis in children: a retrospective study. J Pediatr Orthop 2:249–254
Baxter Willis R, Rozencwaig R (1996) Pediatric osteomyelitis masquerading as skeletal neoplasia. Orthop Clin North Am 27:625–634
Lopes TD, Reinus WR, Wilson AJ (1997) Quantitative analysis of the plain radiographic appearance of Brodie’s abscess. Invest Radiol 32:51–58
Rasool MN (2001) Primary subacute haematogenous osteomyelitis in children. J Bone Jt Surg Br 83B:93–98
Oudjhane K, Azouz EM (2001) Imaging of osteomyelitis in children. Radiol Clin North Am 39:251–266
Grey AC, Davies AM, Mangham DC, Grimer RJ, Ritchie DA (1998) The Penumbra sign on T1-weighted MR imaging in subacute osteomyelitis: frequency, cause and significance. Clin Radiol 53:587–592
Marui T, Yamamoto T, Akisue T, Nakatani T, Hitora T, Nagira K, Yoshiya S, Kurosaka M (2002) Subacute osteomyelitis of long bones: diagnostic usefulness of the penumbra sign on MRI. Clin Imag 26:314–318
Davies AM, Grimer RJ (2004) Tips and Tricks in Radiology: the penumbra sign in subacute osteomyelitis. Eur Radiol. DOI 10.1007/s00330-004-2435-9
Manaster BJ, Disler DG, May DA (2002) Musculoskeletal imaging: the requisites, 2nd edn. Mosby, St Louis pp 515–518
Resnick D (2002) Diagnosis of bone and joint disorders, 4th edn. WB Saunders Co., Philadelphia pp 2379–2396
Rafii M, Firooznia H, Golimbu C, McCauley DI (1984) Hematogenous osteomyelitis with fat–fluid level shown by CT. Radiology 153:493–494
Hui CL, Naidoo P (2003) Extramedullary fat fluid level on MRI as a specific sign for osteomyelitis: case report. Australas Radiol 47:443–446
Resnick D (2002) Diagnosis of bone and joint disorders, 4th edn. WB Saunders Co., Philadelphia p 3633
Sundaram M, Khanna G, El Khoury GY (2001) T1-weighted MR imaging for distinguishing large osteolysis of Paget’s disease from sarcomatous change. Skeletal Radiol 30:378–383
López C, Thomas DV, Davies AM (2003) Neoplastic transformation and tumour-like lesions in Paget’s disease of bone: a pictorial review. Eur Radiol 13:L151–L163
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Davies, A.M., Hughes, D.E. & Grimer, R.J. Intramedullary and extramedullary fat globules on magnetic resonance imaging as a diagnostic sign for osteomyelitis. Eur Radiol 15, 2194–2199 (2005). https://doi.org/10.1007/s00330-005-2771-4
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00330-005-2771-4