Image guided interventions in spinal infections

Impact of radiation dose reduction and iterative image reconstruction on CT-guided spine biopsies

This study aimed to systematically evaluate the impact of dose reduction on image quality and confidence for intervention planning and guidance regarding computed tomography (CT)-based intervertebral disc and vertebral body biopsies. We retrospectively analyzed 96 patients who underwent multi-detector CT (MDCT) acquired for the purpose of biopsies, which were either derived from scanning with standard dose (SD) or low dose (LD; using tube current reduction). The SD cases were matched to LD cases considering sex, age, level of biopsy, presence of spinal instrumentation, and body diameter. All images for planning (reconstruction: "IMR1") and periprocedural guidance (reconstruction: "iDose4") were evaluated by two readers (R1 and R2) using Likert scales. Image noise was measured using attenuation values of paraspinal muscle tissue. The dose length product (DLP) was statistically significantly lower for LD scans regarding the planning scans (SD: 13.8 ± 8.2 mGy*cm, LD: 8.1 ± 4.4 mGy*cm, p < 0.01) and the interventional guidance scans (SD: 43.0 ± 48.8 mGy*cm, LD: 18.4 ± 7.3 mGy*cm, p < 0.01). Image quality, contrast, determination of the target structure, and confidence for planning or intervention guidance were rated good to perfect for SD and LD scans, showing no statistically significant differences between SD and LD scans (p > 0.05). Image noise was similar between SD and LD scans performed for planning of the interventional procedures (SD: 14.62 ± 2.83 HU vs. LD: 15.45 ± 3.22 HU, p = 0.24). Use of a LD protocol for MDCT-guided biopsies along the spine is a practical alternative, maintaining overall image quality and confidence. Increasing availability of model-based iterative reconstruction in clinical routine may facilitate further radiation dose reductions.

Review article: the current status of CT-guided needle biopsy of the spine

CT-guided percutaneous needle biopsy of the spine is a well-described technique for determining the nature of indeterminate vertebral lesions or establishing a diagnosis of spinal infection, the high diagnostic accuracy and the safety of the procedure having been extensively documented. The purpose of the current article is to review the literature to date on CT-guided spinal biopsy. Specifically, indications for spinal biopsy, techniques for optimising yield, detail of the approaches for various spinal levels which is dependent upon both the region within the spinal column and lesion location within the vertebra (body vs. neural arch), determinants of biopsy outcome and complications are covered. It is hoped that the review will be of particular benefit to junior radiologists who are required to perform this procedure.

Update on spinal epidural abscess

PURPOSE OF REVIEW

Spinal epidural abscess (SEA) is still a rare but potentially very morbid infection of the spine. In recent years, the incidence has risen sharply but the condition remains a medical conundrum wrought with unacceptably long diagnostic delays. The outcome depends on timely diagnosis and missed opportunities can be associated with catastrophic consequences. Management and outcomes have improved over the past decade. This review focuses on risk factors and markers that can aid in establishing the diagnosis, the radiological characteristics of SEA on MRI and their clinical implications, as well as the importance of establishing clear indications for surgical decompression.

RECENT FINDINGS

This once exclusively surgically managed entity is increasingly treated conservatively with antimicrobial therapy. Patients diagnosed in a timely fashion, prior to cord involvement and the onset of neurologic deficits can safely be managed without decompressive surgery with targeted antimicrobial therapy. Patients with acute cord compression and gross neurologic deficits promptly undergo decompression. The greatest therapeutic dilemma remains the group with mild neurological deficits. As failure rates of delayed surgery approach 40%, recent research is focused on predictive models for failure of conservative SEA management. In addition, protocols are being implemented with some success, to shorten the diagnostic delay of SEA on initial presentation.

SUMMARY

SEA is a potentially devastating condition that is frequently missed. Protocols are put in place to facilitate early evaluation of back pain in patients with red flags with appropriate cross-sectional imaging, namely contrast-enhanced MRI. Efforts for establishing clear-cut indications for surgical decompression of SEA are underway.