Brodie's Abscess Case Study

Clinical History

A 40 year old male patient presented with gradually increasing severe pain localized to the left foot. The pain was exacerbated with walking and there were no associated systemic symptoms present such as fever. Upon examination, severe tenderness was present in the ankle, as well as pain with motion, and limitation of flexion and extension. The patient was referred for a bone scan to ascertain the nature of the localized skeletal problem.

Imaging Findings

Examination Protocol*:

Scanning was performed on the Symbia T6 TruePoint SPECT·CT system after injection of 20 mCi 99mTc MDP. A planar spot view of the ankles showed a focal hot spot in the ankle confirming the solitary nature of the pathology.*

Scanner- Symbia T6

SPECT
Injection: 20 mCi 99mTc MDP Scan delay - 3 hours Matrix - 128x128 Rotation time - 30 sec/frame Frames - 64 frames/rotation Rotation - 180 degrees dual heads Reconstruction - Flash 3D

CT
Number of Slices - 6
Effective mAs - 45
keV - 130
Rotation time - 1
sec Slice collimation - 1 mm
Slice width - 1.25 mm
Acquisition time <20 sec

Findings:

The SPECT·CT scan demonstrated a focal area of intense tracer uptake in the left ankle, just proximal to the lower end of the tibia. Fusion with thin slice CT data and reconstruction in various oblique planes and volume rendering of fused datasets using FusedVision3D showed the focal hot spot to be located within the left middle cuneiform bone. Thin slice CT reconstructed in oblique orientations demonstrated a small central zone of osteolysis within the middle cuneiform bone, showing surrounding sclerotic changes.

Diagnosis

This appearance is typical of Brodie's abscess. Fused images showing the area of maximum intensity from the SPECT study to be exactly localized to the central zone of osteolysis, confirmed the diagnosis of Brodie's abscess. The zone of bony sclerosis around the lytic zone showed lower radiotracer uptake. Analysis of the fused images suggested that the radiotracer uptake extended to the adjacent joint space between the navicular and cuneiform bones which suggested a possible extension of the infective process into the joint space with major clinical consequences.

Discussion

Brodie’s abscess is a chronic infective process with osteolysis in the bone, surrounded by dense fibrous tissue and sclerotic bone. It is common in children and usually seen in the metaphysic of long bones especially of the lower extremities. It is occasionally found in adults. The usual symptom is severe localized pain. In the early stages, routine X ray as well as CT may be normal. A bone scan is highly sensitive in the detection of early Brodie's abscess and this has led to the increased usage of bone SPECT for localization of the lesion especially in the metaphysic of bones of the extremities for which early treatment is important to limit damage to the growth plate and prevent bone deformities and underdevelopment. CT is usually positive almost 4 weeks after onset of active osteomyelitis. Bone SPECT has the advantage of being able to detect such focal osteomyelitis very early, before it is evident on radiography or CT, and at a stage when it is potentially curable with antibiotics with prevention of long term sequelae. Due to limited spatial resolution of bone SPECT, the fusion of high quality spiral CT and SPECT is the ideal approach for complete evaluation of such disease processes.

In this study, CT was used for attenuation correction of bone SPECT. The corrected SPECT data was fused to a thin slice CT dataset reconstructed with sharp kernel and with bone window settings in order to evaluate bone abnormalities correctly on CT. The CT findings of central lucent lesions with peripheral bony sclerosis are typical of Brodie's abscess. Since the findings were visualized, in this particular case it was obvious that the lesion was fairly advanced at the time of scanning. Exact coregistration, due to sequential SPECT and CT scanning at the same patient position was essential for the exact localization of the lesion to the left middle cuneiform bone within the arch of left foot. The anteroposterior diameter of the middle cuneiform was just 1.4 cm. Brodie's abscess within the small tarsal bones in the ankle is not common although it is very common in the lower end of tibia. Analysis of recent literature for similar lesions in small tarsal bones shows a single case report of Brodie's abscess in the cuboid bone (1). There are isolated reports of Brodie’s abscess in talus and calcaneus (2). To date and to the author's knowledge, Brodie's abscess in cuneiform bone has not been reported. This is the first such case to be reported especially with localization using diagnostic CT and SPECT fusion. Only because of the high quality data from the SPECT·CT scan, particularly the fusion of SPECT with thin slice spiral CT, the exact localization within the small tarsal bone was possible. Also to be noted is the fact that the maximum intensity of the hot spot correlates exactly to the lytic hypodense zone of the middle cuneiform bone in the CT. This proves the value of exact coregistration to high quality CT as is fostered by SPECT·CT.

Data courtesy of Dr. Shahid Mahmood of Gleneagles Hospital, Singapore.

References:

1. Brodie's abscess in Cuboid Bone - A case report - Bagatur et al. - Clin Orthop Relat Res. 2003 Mar;(408):292-4.
2. Brodie's abscess. Considerations on 5 cases - Furlanetto et al. - Minerva Ortop. 1968 Dec;19(12):782-8
*Any of the protocols presented herein are for informational purposes and are not meant to substitute for any clinicians' judgment in how best to use any medical devices. It is the clinician that makes all diagnostic determinations based upon education, learning and experience.