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Spinal and paraspinal infection: value of diffusion-weighted imaging 2006

General Spine

Toshio . Moritani, MD, PhD, Non ASSR Member
Wendy R.K. Smoker, MD, FACR, Non ASSR Member
Bruno Policeni, MD, Non ASSR Member
Anietie Okon, MD, Non ASSR Member

Scientific Paper

Purpose

To evaluate the utility of diffusion-weighted imaging (DWI) in spinal and paraspinal infection

Methods & Materials

We reviewed DWI findings in 20 patients (18 male and 2 female; age range: 22 - 76 years, mean age: 53 years) with spinal and paraspinal infection, including epidural, paraspinal and psoas abscesses, discitis, osteomyelitis and meningitis. The diagnosis was made based on clinical, laboratory and imaging findings. Causal organisms were proven in 11 patients. Clinical symptoms were fever, neck pain, low back pain, weakness, and mental status changes. Eight patients sustained infection after spine surgery or tumor resection. Conventional MRI and DWI with ADC maps (b=0, 1000 sec/mm2, 3 orthogonal orientations) were acquired. Regions of interest (0.2-1.8 cm2) were placed manually on the ADC map and ADC values were calculated.

Results

There were epidural abscess in 7 patients, psoas and paraspinal abscess in 8, discitis in 5, osteomyelitis in 6, and meningitis in 2. Gd-T1 weighted images showed epidural, psoas and paraspinal abscesses as rim-enhancing cystic lesions, which are occasionally difficult to differentiate from postsurgical seroma, pseudomeningocele, granulation tissue, disc herniation, and residual/recurrent tumor. DWI showed these abscesses as hyperintense in all patients. Decreased ADC values were observed in the cystic areas of abscesses: epidural abscess (0.93�0.25�10-3mm2/s, mean � standard deviation); and psoas and paraspinal abscess (0.81�0.24�10-3mm2/s), in comparison with the CSF (2.45�0.48�10-3mm2/s), muscle (1.44�0.24�10-3mm2/s), postoperative fluid collection (2.98�0.34�10-3mm2/s). Although ADC values of residual or recurrent tumor were low (0.84�0.10�10-3mm2/s), it represented the solid portion of tumor.

Conclusion

DWI is useful in the detection of epidural, paraspinal and psoas abscesses, and in differentiating them from postsurgical fluid collections, recurrent/residual tumor and other pathologies.

References

N/A

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