•
Nuclear Medicine
Diagnosis of Osteomyelitis in Children by Combined Blood Pool and Bone Imaging 1 David L. Gilday, M.D., B.Eng., F.R.C.P.(C), Donald J. Paul, M.D., and Jane Paterson Differentiation of osteomyelitis from cellulitis or septic arthritis can be difficult. The radiological examination often does not have the characteristic features. Seventy of 71 children with osteomyelitis had focal areas of increased radioactivity at the site of the infection. The addition of "blood pool" images aids in the interpretation of the study as they permit evaluation of the effect of hyperemia. The 13 children with cellulitis had diffuse increase in radioactivity involving both the bones and soft tissues. Bone imaging as the initial screening procedure for osteomyelitis is recommended. INDEX TERMS:
Bones. infection. Bones. radionuclide studies. Cellulitis. Joints, infec-
tion Radiology 117:331-335, November 1975
•
•
CHILDREN, the diagnosis of osteomyelitis is frequently difficult. The child may present with bone pain, joint tenderness, soft-tissue. swelling and erythema, fever and bacteremia, but the differentiation from pure cellulitis may be difficult. Unfortunately, the radiological examination may yield a wide range of findings: normal, soft-tissue swelling and, in some, the frank bone changes of osteomyelitis (1). The therapeutic management of osteomyelitis usually involves a minimum of twenty-one days of intravenous antibiotics whereas cellulitis usually requires only ten days of therapy. Therefore it is imperative to make the correct diagnosis as soon as possible. Using combined "blood pool" and bone imaging, we found it possible to differentiate osteomyelitis from cellulitis and to do so very early in the course of the patient's illness.
Table I:
I
N
METHOD
In most of our patients undergoing bone imaging, especially those thought to have osteomyelitis, we obtain "blood pool" images of the suspected area immediately after the injection of 99mTc methylene diphosphonate and delayed images of bone after 1 to 2 hours. "Blood pool" imaging is performed with an information density of 1500 counts/cm 2 using a gamma camera (Dynacamera 2C or 4) with the General Purpose Low Energy Collimator (10,000 holes). The delayed images of the same area are obtained with an information density of 1500 counts/cm 2 over the appropriate bone with the Ultrafine Resolution Low Energy Collimator (25,800 holes). The routine study consists of immediate images, usually anterior views, and delayed images which are anterior and, often, lateral and posterior ones as needed 1
Radionucl ide I mage Diagnosis of Osteomyelitis
Image Diagnosis* Normal Osteomyel itis Cellulitis Septic arthritis Total
,..-Discharge Diagnosis-----, Septic ArthOsteoCelluritis Normal myelitis litis
43
1 70
1 13
43
71
8 9
13
* Results based on radionuclide image report, not single observer review. Table II:
Location of Osteomyelitis
Skull Spine Pelvis Long bones Hands and feet
11 7
12
27 14
to delineate any abnormalities, using the gamma camera in all cases. In some instances pinhole views are also obtained to delineate small structures such as carpal, tarsal or spinal lesions. Although this was a prospective study, each image interpretation was taken from the opinion rendered on the report, as was the radiological diagnosis. The bone image diagnosis of osteomyelitis was based on the characteristic findings of a focal, well-defined area of increased radioactivity in the delayed image associated with an area of increased radioactivity in the "blood pool" image. The confidence in this diagnosis was increased if the clinical findings fitted the diagnosis of osteomyelitis. This was felt to be the fairest method of as. sessing the clinical value of each diagnostic method. The diagnosis of osteomyelitis was often established by the radiological and bone image findings, but for this
From the Division of Nuclear Medicine. The Hospital for Sick Children. Toronto. Ontario, Canada. Accepted for publication in May 1975.
331
dk
332
DAVID L. GILDAY AND OTHERS
November 1975
A
•
L
R
L
R
Fig. 1. Epiphyseal osteomyelitis. A . This 14-year-old boy has hyperemia in the right distal femur (metaphysis and medial condyle) seen as increased radioactivity in the "blood pool" image. B. The bone image has a similar but more pronounced increase. Typical image findings of osteomyelitis (staphylococcal) in an unusual location. C. The tomograms demonstrate a lytic lesion in the same location.
L AA
A
B
Fig. 2. Subacute osteomyelitis. This 3-year-old boy suddenly began to limp and the initial radiographs were normal. A and B. The bone images demonstrated a diffuse increase in rad ioactivity invoiving the whole forefoot. but there was a superimposed focus in the cuboid. C. Two weeks later the radiographs became abnormal, confirming the diagnosis of osteomyelitis.
project an attempt was made to find other confirmatory evidence. Blood cultures or cultures from fluid drained from osteomyelitic foci were positive in 26 patients. Prompt response to antibiotic therapy in 42 children was the clinical evidence favoring the diagnosis, and in 3 patients a combination of radiological and radionuclide findings and eventual response to antibiotics permitted the diagnosis. RESULTS
We examined 134 patients suspected of having os-
teomyelitis (TABLE I). The radionuclide diagnosis was correct in 70 of the 71 patients ultimately concluded to have osteomyelitis, with only one image being normal. The 13 patients with cellulitis and no osteomyelitis component and 8 of the 9 patients with pure septic arthritis had positive bone images suggesting their diagnoses. All of the 43 normal patients had normal images. The distribution of the osteomyelitic foci was slightly different from that expected, with an increased number of lesions in the spine, pelvis and skull (TABLE II) which are more difficult to diagnose clinically and radiologically (2). The radiological examination was correct in 29 of 66
Vol. 117
DIAGNOSIS OF OSTEOMYELITIS BY BLOOD POOL AND BONE IMAGING
· B-'1'1-74
B
333
Nuclear Medicine
8-'1'1-74
Fig. 3. Diskitis-osteomyelitis. This 12-year-old girl had pain in the back. A. The spinal radiographs demonstrated narrowing of the L 1 _ 2 disk space. B. The bone image shows increased radioactivity in the vertebral bodies adjacent to the narrowed disk space. C. These are better visualized in the pinhole magnifica tion view.
c
--- --- DD ~
Fig. 4. Cellulitis. A swollen left arm and fever developed in this 3-year-old girl. A and B. The " blood pool " images demonstrated diffuse increase in radioactivity of the whole left forearm due to hyperemia . C and D. In the bone images this was reflected by a diffuse increase in both the bones and soft tissues.
patients with osteomyelitis and 8 had changes which suggested osteomyelitis or cellulitis (TABLE III). The radiological examination also was poorer at differentiating osteomyelitis from cellulitis and septic arthritis and, in fact, the interpretation was falsely positive in 3 cases. DISCUSSION
The typical appearance of osteomyelitis (Fig. 1) was
a well-defined focus of increased radioactivity in the bone image, associated with an identical area of hyperemia in the " blood pool" images. Occasionally the focal increase was superimposed on a more diffuse increase secondary to generalized hyperemia (Fig. 2). This appeared to be quite specific for osteomyelitis and the differentiation from the patterns of cellulitis and septic arthritis was usually easy (TABLE IV). The " blood pool" images were less valuable in the spine due to the
334
DAVID L. GILDAY AND OTHERS
underlying organs (liver and gut), but the bone image demonstrated the abnormal vertebral bodies involved in the diskitis-osteomyelitis, usually confirming the radiological diagnosis of diskitis (Fig. 3). The appearance of cellulitis was that of a diffuse increase in radioactivity involving the soft tissues and the bone (Fig. 4). This was readily apparent in both the "blood pool" and bone images as being due to diffuse soft-tissue hyperemia with no focal bone component (T ABLE IV). Septic arthritis has a very similar appearance due to the hyperemia involving the joint (Fig. 5). Table III :
Radiological Diagnosis of Osteomyel itis Discharge Diagnosis-------, Septic Os teoCelluArthmyelitis lit is r itis
rr-r--:
Radiological Diagnosis* Normal Probable osteomyelitis Soft-tissue swelling Arthritis Not available Total
28
3
29
2
8 0 6
6 0 2 13
71
November 1975
The bone image was found to be positive as early as 24 hours after the onset of symptoms, which was well before any bony changes were evident in the radiographs (Fig. 6). Occasionally, however, soft-tissue swelling or indistinct fat lines permitted the presumptive diagnosis of osteomyelitis. The bone image had its greatest value in assessing areas difficult to evaluate by radiological means, such as the pelvis and spine. These areas do not have the readily displayed flat planes of the long bones and, therefore, the early diagnosis of osteomyelitis could only be made by bone imaging (Fig. 7). We are now confident that if a child has clinical symptoms suggesting osteomyelitis, then the examina-
~;~
4 1 2 2
0
9
* Results based on radiological report, not single observer rev iew. Table IV:
Radionuclide Image Patterns in Skeletal Inflammation
Inflammation
Blood Pool Image
Osteomyelitis Cellulitis Septic arthrit is
Focal t Diffuse t Diffuse t
-
- - -
-
-
-
-- ----
Bone Image
- - -Focal t ± diffuse t
Diffuse t soft tissue Diffuse t periarticular
Fig. 5. Septic arthritis. This 11-year-old child had a hot swollen wrist. A and B. In both the " blood pool" and bone images there was diffusely increased radioactivity throughout the whole carpus, indicating the synovial hyperemia.
A
Fig. 6. Acute staphylococcal osteomyelitis. A. The bone image was abnormal, indicating the osteomyelitis in the distal tibial metaphysis 24 hours after the onset of symptoms. . Band C. The radiographs were normal.
DIAGNOSIS OF OSTEOMYELITIS BY BLOOD POOL AND BONE IMAGING
Vol. 117
L
335
Nuclear Medicine
R
p
A
Fig. 7. Ischial osteomyelitis . This 11-year-old boy was investigated intensively for a painful left buttock. A. The bone image demonstrated marked uptake in the ischium. Band C. Routine radiographs and tomograms were normal . The child improved dramatically with antibiotic therapy.
tion which can most readily give the correct answer is bone imaging. This is especially true early in the illness or if the axial skeleton is involved. REFERENCES 1. Capitanio MA. Kirkpatrick JA: Early roentgen observations in acute osteomyelitis. Am J Roentgenol 108:488-496. Mar 1970
2. Waldvogel FA. Medoff G. Swartz MN: Osteomyelitis: a review of clinical features. therapeutic considerations and unusual aspects. New Eng J Med 282:198-206. 22 Jan 1970; 282: 260-266. 29 Jan 1970 Division of Nuclear Medicine Hospital for Sick Children 555 University Avenue Toronto. Ontario. Canada M5G 1X8
Nuclear Medicine
Diagnosis of Osteomyelitis in Children by Combined Blood Pool and Bone Imaging 1 David L. Gilday, M.D., B.Eng., F.R.C.P.(C), Donald J. Paul, M.D., and Jane Paterson Differentiation of osteomyelitis from cellulitis or septic arthritis can be difficult. The radiological examination often does not have the characteristic features. Seventy of 71 children with osteomyelitis had focal areas of increased radioactivity at the site of the infection. The addition of "blood pool" images aids in the interpretation of the study as they permit evaluation of the effect of hyperemia. The 13 children with cellulitis had diffuse increase in radioactivity involving both the bones and soft tissues. Bone imaging as the initial screening procedure for osteomyelitis is recommended. INDEX TERMS:
Bones. infection. Bones. radionuclide studies. Cellulitis. Joints, infec-
tion Radiology 117:331-335, November 1975
•
•
CHILDREN, the diagnosis of osteomyelitis is frequently difficult. The child may present with bone pain, joint tenderness, soft-tissue. swelling and erythema, fever and bacteremia, but the differentiation from pure cellulitis may be difficult. Unfortunately, the radiological examination may yield a wide range of findings: normal, soft-tissue swelling and, in some, the frank bone changes of osteomyelitis (1). The therapeutic management of osteomyelitis usually involves a minimum of twenty-one days of intravenous antibiotics whereas cellulitis usually requires only ten days of therapy. Therefore it is imperative to make the correct diagnosis as soon as possible. Using combined "blood pool" and bone imaging, we found it possible to differentiate osteomyelitis from cellulitis and to do so very early in the course of the patient's illness.
Table I:
I
N
METHOD
In most of our patients undergoing bone imaging, especially those thought to have osteomyelitis, we obtain "blood pool" images of the suspected area immediately after the injection of 99mTc methylene diphosphonate and delayed images of bone after 1 to 2 hours. "Blood pool" imaging is performed with an information density of 1500 counts/cm 2 using a gamma camera (Dynacamera 2C or 4) with the General Purpose Low Energy Collimator (10,000 holes). The delayed images of the same area are obtained with an information density of 1500 counts/cm 2 over the appropriate bone with the Ultrafine Resolution Low Energy Collimator (25,800 holes). The routine study consists of immediate images, usually anterior views, and delayed images which are anterior and, often, lateral and posterior ones as needed 1
Radionucl ide I mage Diagnosis of Osteomyelitis
Image Diagnosis* Normal Osteomyel itis Cellulitis Septic arthritis Total
,..-Discharge Diagnosis-----, Septic ArthOsteoCelluritis Normal myelitis litis
43
1 70
1 13
43
71
8 9
13
* Results based on radionuclide image report, not single observer review. Table II:
Location of Osteomyelitis
Skull Spine Pelvis Long bones Hands and feet
11 7
12
27 14
to delineate any abnormalities, using the gamma camera in all cases. In some instances pinhole views are also obtained to delineate small structures such as carpal, tarsal or spinal lesions. Although this was a prospective study, each image interpretation was taken from the opinion rendered on the report, as was the radiological diagnosis. The bone image diagnosis of osteomyelitis was based on the characteristic findings of a focal, well-defined area of increased radioactivity in the delayed image associated with an area of increased radioactivity in the "blood pool" image. The confidence in this diagnosis was increased if the clinical findings fitted the diagnosis of osteomyelitis. This was felt to be the fairest method of as. sessing the clinical value of each diagnostic method. The diagnosis of osteomyelitis was often established by the radiological and bone image findings, but for this
From the Division of Nuclear Medicine. The Hospital for Sick Children. Toronto. Ontario, Canada. Accepted for publication in May 1975.
331
dk
332
DAVID L. GILDAY AND OTHERS
November 1975
A
•
L
R
L
R
Fig. 1. Epiphyseal osteomyelitis. A . This 14-year-old boy has hyperemia in the right distal femur (metaphysis and medial condyle) seen as increased radioactivity in the "blood pool" image. B. The bone image has a similar but more pronounced increase. Typical image findings of osteomyelitis (staphylococcal) in an unusual location. C. The tomograms demonstrate a lytic lesion in the same location.
L AA
A
B
Fig. 2. Subacute osteomyelitis. This 3-year-old boy suddenly began to limp and the initial radiographs were normal. A and B. The bone images demonstrated a diffuse increase in rad ioactivity invoiving the whole forefoot. but there was a superimposed focus in the cuboid. C. Two weeks later the radiographs became abnormal, confirming the diagnosis of osteomyelitis.
project an attempt was made to find other confirmatory evidence. Blood cultures or cultures from fluid drained from osteomyelitic foci were positive in 26 patients. Prompt response to antibiotic therapy in 42 children was the clinical evidence favoring the diagnosis, and in 3 patients a combination of radiological and radionuclide findings and eventual response to antibiotics permitted the diagnosis. RESULTS
We examined 134 patients suspected of having os-
teomyelitis (TABLE I). The radionuclide diagnosis was correct in 70 of the 71 patients ultimately concluded to have osteomyelitis, with only one image being normal. The 13 patients with cellulitis and no osteomyelitis component and 8 of the 9 patients with pure septic arthritis had positive bone images suggesting their diagnoses. All of the 43 normal patients had normal images. The distribution of the osteomyelitic foci was slightly different from that expected, with an increased number of lesions in the spine, pelvis and skull (TABLE II) which are more difficult to diagnose clinically and radiologically (2). The radiological examination was correct in 29 of 66
Vol. 117
DIAGNOSIS OF OSTEOMYELITIS BY BLOOD POOL AND BONE IMAGING
· B-'1'1-74
B
333
Nuclear Medicine
8-'1'1-74
Fig. 3. Diskitis-osteomyelitis. This 12-year-old girl had pain in the back. A. The spinal radiographs demonstrated narrowing of the L 1 _ 2 disk space. B. The bone image shows increased radioactivity in the vertebral bodies adjacent to the narrowed disk space. C. These are better visualized in the pinhole magnifica tion view.
c
--- --- DD ~
Fig. 4. Cellulitis. A swollen left arm and fever developed in this 3-year-old girl. A and B. The " blood pool " images demonstrated diffuse increase in radioactivity of the whole left forearm due to hyperemia . C and D. In the bone images this was reflected by a diffuse increase in both the bones and soft tissues.
patients with osteomyelitis and 8 had changes which suggested osteomyelitis or cellulitis (TABLE III). The radiological examination also was poorer at differentiating osteomyelitis from cellulitis and septic arthritis and, in fact, the interpretation was falsely positive in 3 cases. DISCUSSION
The typical appearance of osteomyelitis (Fig. 1) was
a well-defined focus of increased radioactivity in the bone image, associated with an identical area of hyperemia in the " blood pool" images. Occasionally the focal increase was superimposed on a more diffuse increase secondary to generalized hyperemia (Fig. 2). This appeared to be quite specific for osteomyelitis and the differentiation from the patterns of cellulitis and septic arthritis was usually easy (TABLE IV). The " blood pool" images were less valuable in the spine due to the
334
DAVID L. GILDAY AND OTHERS
underlying organs (liver and gut), but the bone image demonstrated the abnormal vertebral bodies involved in the diskitis-osteomyelitis, usually confirming the radiological diagnosis of diskitis (Fig. 3). The appearance of cellulitis was that of a diffuse increase in radioactivity involving the soft tissues and the bone (Fig. 4). This was readily apparent in both the "blood pool" and bone images as being due to diffuse soft-tissue hyperemia with no focal bone component (T ABLE IV). Septic arthritis has a very similar appearance due to the hyperemia involving the joint (Fig. 5). Table III :
Radiological Diagnosis of Osteomyel itis Discharge Diagnosis-------, Septic Os teoCelluArthmyelitis lit is r itis
rr-r--:
Radiological Diagnosis* Normal Probable osteomyelitis Soft-tissue swelling Arthritis Not available Total
28
3
29
2
8 0 6
6 0 2 13
71
November 1975
The bone image was found to be positive as early as 24 hours after the onset of symptoms, which was well before any bony changes were evident in the radiographs (Fig. 6). Occasionally, however, soft-tissue swelling or indistinct fat lines permitted the presumptive diagnosis of osteomyelitis. The bone image had its greatest value in assessing areas difficult to evaluate by radiological means, such as the pelvis and spine. These areas do not have the readily displayed flat planes of the long bones and, therefore, the early diagnosis of osteomyelitis could only be made by bone imaging (Fig. 7). We are now confident that if a child has clinical symptoms suggesting osteomyelitis, then the examina-
~;~
4 1 2 2
0
9
* Results based on radiological report, not single observer rev iew. Table IV:
Radionuclide Image Patterns in Skeletal Inflammation
Inflammation
Blood Pool Image
Osteomyelitis Cellulitis Septic arthrit is
Focal t Diffuse t Diffuse t
-
- - -
-
-
-
-- ----
Bone Image
- - -Focal t ± diffuse t
Diffuse t soft tissue Diffuse t periarticular
Fig. 5. Septic arthritis. This 11-year-old child had a hot swollen wrist. A and B. In both the " blood pool" and bone images there was diffusely increased radioactivity throughout the whole carpus, indicating the synovial hyperemia.
A
Fig. 6. Acute staphylococcal osteomyelitis. A. The bone image was abnormal, indicating the osteomyelitis in the distal tibial metaphysis 24 hours after the onset of symptoms. . Band C. The radiographs were normal.
DIAGNOSIS OF OSTEOMYELITIS BY BLOOD POOL AND BONE IMAGING
Vol. 117
L
335
Nuclear Medicine
R
p
A
Fig. 7. Ischial osteomyelitis . This 11-year-old boy was investigated intensively for a painful left buttock. A. The bone image demonstrated marked uptake in the ischium. Band C. Routine radiographs and tomograms were normal . The child improved dramatically with antibiotic therapy.
tion which can most readily give the correct answer is bone imaging. This is especially true early in the illness or if the axial skeleton is involved. REFERENCES 1. Capitanio MA. Kirkpatrick JA: Early roentgen observations in acute osteomyelitis. Am J Roentgenol 108:488-496. Mar 1970
2. Waldvogel FA. Medoff G. Swartz MN: Osteomyelitis: a review of clinical features. therapeutic considerations and unusual aspects. New Eng J Med 282:198-206. 22 Jan 1970; 282: 260-266. 29 Jan 1970 Division of Nuclear Medicine Hospital for Sick Children 555 University Avenue Toronto. Ontario. Canada M5G 1X8
