Positron emission tomography in spinal infections

18F-NaF PET/CT in Presumed Aseptic Pseudarthrosis after Spinal Fusion: Correlation with Findings at Revision Surgery and Intraoperative Cultures

Background Conventional imaging is useful to assess interbody fusion by showing complete trabecular bony bridging, but has a low positive predictive value for pseudarthrosis. Because alterations of bone metabolism may precede structural anatomical changes on computed tomography (CT), we aimed to investigate the ability of fluorine 18 sodium fluoride positron emission tomography/computed tomography (18F-NaF PET/CT) to identify pseudarthrosis after spinal fusion using surgical revision as the reference standard.

Methods We retrospectively reviewed 18F-NaF PET/CT scans performed between February 2019 and September 2020 in patients experiencing pain after spinal fusion. We included the 18 patients who underwent revision surgery for suspicion of pseudarthrosis. Five consecutive patients who were clearly fused on CT served as the control group.

Results In the revision surgery group (n=18), visual assessment by 18F-NaF PET/CT revealed that all 22 cages with an increased 18F-NaF uptake around intercorporal fusion material had mobility at revision surgery, whereas none of the fused patients (n=5) showed uptake around cage/intervertebral disk space. Among the 18 patients with presumed aseptic pseudarthrosis, intraoperative cultures revealed surgical site infection (SSI) caused by Cutibacterium acnes (C. acnes) in seven patients (38.9%). There was a statistically significant difference in standardized uptake values and uptake ratios between the revision surgery and control groups (p=5.3× 10−6 and p=0.0002, respectively).

Conclusions 18F-NaF PET/CT imaging appeared as a useful tool to identify pseudarthrosis following spinal fusion. The unexpectedly high prevalence (38.9%) of SSI caused by C. acnes found in presumed aseptic patients supports the utility of intraoperative cultures in revision cases for pseudarthrosis, even without preoperative clinical suspicion of SSI.

Postoperative Spinal Implant Infections (PSII)-A Systematic Review: What Do We Know So Far and What is Critical About It?

STUDY DESIGN

Systematic review.

OBJECTIVES

Postoperative spinal implant infections (PSII) are an increasing challenge in the daily clinical routine. This review summarizes existing knowledge in the field of PSII, including definitions, epidemiology, classifications, risk factors, pathogenesis, symptoms, diagnosis, and treatment.

METHODS

A systematic review was performed using a structured PubMed analysis, based on the PRISMA criteria. The search terminology was set as: "spinal implant associated infection OR spinal implant infection OR spinal instrumentation infection OR peri spinal implant infection." PubMed search was limited to the categories randomized controlled trials (RCT), clinical trials, meta-analysis and (systematic) reviews, whereas case reports were excluded. Studies from January 2000 to December 2020 were considered eligible. A total of 572 studies were identified, 82 references included for qualitative synthesis, and 19 for detailed sub analysis (12 meta-analysis, 7 prospective RCT).

RESULTS

Structural problems in the field of PSII were revealed, including (1) limited level of evidence in clinical studies (missing prospective RCT, metanalyzes), (2) small patient numbers, (3) missing standardized definitions, (4) heterogeneity in patient groups, and (5) redundancy in cited literature.

CONCLUSION

Evidence-based knowledge about spinal implant-associated infections is lacking. All involved medical fields should come together to define the term PSII and to combine their approaches toward research, training, and patient care.

Celecoxib promotes survival and upregulates the expression of neuroprotective marker genes in two different in vitro models of Parkinson's disease

Parkinson's disease (PD) is the second most common age-related neurodegenerative disorder after Alzheimer's disease. Increasing evidence highlights the role of age-related chronic inflammation, oxidative stress and mitochondrial dysfunction in the pathogenesis of PD. A combination of these factors impairs the crosstalk between mitochondria and lysosomes, resulting in compromised cell homeostasis. Apolipoprotein D (APOD), an ancient and highly conserved anti-inflammatory and antioxidant lipocalin, and the transcription factor EB (TFEB), a master regulator of mitophagy, autophagy and lysosomal biogenesis, play key roles in these processes. Both APOD and TFEB have attracted attention as therapeutic targets for PD. The aim of this study was to investigate if the selective cyclooxygenase-2 inhibitor celecoxib (CXB) exerts a direct neuroprotective effect in 6-hydroxydopamine (6-OHDA) and paraquat (PQ) PD models. We found that CXB rescued SH-SY5Y cells challenged by 6-OHDA- and PQ-induced toxicity. Furthermore, treatment with CXB led to a marked and sustained upregulation of APOD and the two microphthalmia transcription factors TFEB and MITF. In sum, this study highlights the clinically approved drug CXB as a promising neuroprotective therapeutic tool in PD research that has the potential to increase the survival rate of dopaminergic neurons that are still alive at the time of diagnosis.

Experimental Candida albicans osteomyelitis: Microbiologic, antigenic, histologic, and 18FDG-PET-CT imaging characteristics in a newly established rabbit model

Candida osteomyelitis is a debilitating disease that is difficult to diagnose and treat. As there are no animal models or prospective studies for this uncommon infection, little is known about the pathogenesis, diagnosis, or treatment. We therefore sought to establish an animal model for the study of the pathophysiology, diagnostic modalities, and therapeutic interventions of Candida osteomyelitis. We developed a modified version of the Norden rabbit model of tibial osteomyelitis, in which the right tibia was inoculated intraoperatively with different inocula of C. albicans or normal saline as control. On days 7, 14, and 21 after inoculation, the animals underwent bone radiography, 18-fluoro-2-deoxy-D-glucose positron emission tomography combined with computed tomography (PET/CT) scan, and blood sampling for blood cultures, blood counts, erythrocyte sedimentation rate, and Candida mannan antigen serum levels. On day 21, animals were euthanized, and infected tibias harvested for culture and histology. Among eight evaluable animals inoculated with 1 × 106 to 1 × 107 cfu, histology and bone cultures established the presence of Candida osteomyelitis in seven, with a host response of neutrophils, mononuclear cells, multinucleate giant cells, fibrosis, and necrosis. Infected animals demonstrated radiological signs of osteomyelitis with significantly increased tracer uptake in 18FDG-PET/CT scans (P < .01) and elevated serum mannan levels (P < .01). All blood cultures were negative. Indices of inflammation were only slightly increased. In conclusion, we report successful establishment of a new animal model of Candida albicans osteomyelitis that may be applicable to advancing our understanding of the pathophysiology, diagnostic modalities, and treatment of this debilitating infection.

Joint EANM/ESNR and ESCMID-endorsed consensus document for the diagnosis of spine infection (spondylodiscitis) in adults

PURPOSE

Diagnosis of spondylodiscitis (SD) may be challenging due to the nonspecific clinical and laboratory findings and the need to perform various diagnostic tests including serologic, imaging, and microbiological examinations. Homogeneous management of SD diagnosis through international, multidisciplinary guidance would improve the sensitivity of diagnosis and lead to better patient outcome.

METHODS

An expert specialist team, comprising nuclear medicine physicians appointed by the European Association of Nuclear Medicine (EANM), neuroradiologists appointed by the European Society of Neuroradiology (ESNR), and infectious diseases specialists appointed by the European Society of Clinical Microbiology and Infectious Diseases (ESCMID), reviewed the literature from January 2006 to December 2015 and proposed 20 consensus statements in answer to clinical questions regarding SD diagnosis. The statements were graded by level of evidence level according to the 2011 Oxford Centre for Evidence-based Medicine criteria and included in this consensus document for the diagnosis of SD in adults. The consensus statements are the result of literature review according to PICO (P:population/patients, I:intervention/indicator, C:comparator/control, O:outcome) criteria. Evidence-based recommendations on the management of adult patients with SD, with particular attention to radiologic and nuclear medicine diagnosis, were proposed after a systematic review of the literature in the areas of nuclear medicine, radiology, infectious diseases, and microbiology.

RESULTS

A diagnostic flow chart was developed based on the 20 consensus statements, scored by level of evidence according to the Oxford Centre for Evidence-based Medicine criteria.

CONCLUSIONS

This consensus document was developed with a final diagnostic flow chart for SD diagnosis as an aid for professionals in many fields, especially nuclear medicine physicians, radiologists, and orthopaedic and infectious diseases specialists.

Concomitant epidural and subdural spinal abscess: a case report

BACKGROUND CONTEXT

Spinal subdural abscess (SSA) is a rare occurrence for which the management typically involves open surgical removal and washout.

PURPOSE

This case report aims to review the literature and discuss the management of patients with SSA.

STUDY DESIGN

We present a case of a 33-year-old female who presented with a spinal epidural abscess and concurrent SSA. She presented in the context of intravenous (IV) drug use, back pain, and generalized lower extremity weakness.

METHODS

The literature was reviewed with a focus on modern treatment options for SSA. Our patient was managed with IV antibiotics, and separate laminectomies and washouts for both lesions.

RESULTS

The patient recovered well with return of neurologic function and normalization of infection markers. The review of the literature resulted in a management flowchart that will help direct treatment of SSA.

CONCLUSIONS

The literature suggests that in a patient with a definitive diagnosis of SSA, limited surgical management and IV antibiotics are the mainstay of treatment in a patient with a decline in neurologic function. There may be a role for expectant management in the absence of diagnostic imaging or the neurologically stable patient.