Imaging of Spondylodiscitis

Causal Agent Investigation and Treatment of Dogs Diagnosed with Discospondylitis in a Brucella canis Endemic Region

Discospondylitis is a well-recognized disease in dogs, but the relative prevalence of causal infectious agents and efficiency of relevant diagnostic tests are not well-established. Medical record review identified 117 dogs diagnosed with discospondylitis in our clinic over a 5-year period. In 32 dogs, discospondylitis was diagnosed as an incidental imaging finding; 24 of these dogs had concomitant neoplasia. A likely causal infection was identified in 45 of the remaining 85 dogs in which blood and urine cultures, serology for Brucella spp., and galactomannan fungal antigen testing were recommended. Ten dogs were diagnosed with Brucella canis, and ten were diagnosed with suspected fungal infection. Brucella suis serology was negative in all 35 dogs that were tested. Blood cultures were positive in 28 of 71 (39%) tested dogs, and urine culture was positive in 12 of 79 (15%). Cultures were positive from the lesion site of four of eight dogs that underwent surgery and one of the five dogs that underwent image-guided lesion sample collection. Subluxation secondary to discospondylitis was stabilized with metallic implants in four dogs. A similar proportion of known satisfactory treatment outcomes at last follow-up were recorded in dogs that had suspected fungal disease, other bacterial infections, or were Brucella-positive and in those dogs with imaging diagnosis only, although some individuals continued to receive anti-microbial agents or showed recurrent signs. These data support the value of blood culture in discospondylitis and suggest a relatively high prevalence of infection with Brucella spp. and suspected fungal infection.

Imaging of Spondylodiscitis: A Comprehensive Updated Review-Multimodality Imaging Findings, Differential Diagnosis, and Specific Microorganisms Detection

Spondylodiscitis is defined by infectious conditions involving the vertebral column. The incidence of the disease has constantly increased over the last decades. Imaging plays a key role in each phase of the disease. Indeed, radiological tools are fundamental in (i) the initial diagnostic recognition of spondylodiscitis, (ii) the differentiation against inflammatory, degenerative, or calcific etiologies, (iii) the disease staging, as well as (iv) to provide clues to orient towards the microorganisms involved. This latter aim can be achieved with a mini-invasive procedure (e.g., CT-guided biopsy) or can be non-invasively supposed by the analysis of the CT, positron emission tomography (PET) CT, or MRI features displayed. Hence, this comprehensive review aims to summarize all the multimodality imaging features of spondylodiscitis. This, with the goal of serving as a reference for Physicians (infectious disease specialists, spine surgeons, radiologists) involved in the care of these patients. Nonetheless, this review article may offer starting points for future research articles.

Application of Nuclear Medicine Techniques in Musculoskeletal Infection: Current Trends and Future Prospects

Nuclear medicine has become an indispensable discipline in the diagnosis and management of musculoskeletal infections. Radionuclide tests serve as a valuable diagnostic tool for patients suspected of having osteomyelitis, spondylodiscitis, or prosthetic joint infections. The choice of the most suitable imaging modality depends on various factors, including the affected area, potential extra osseous involvement, or the impact of previous bone/joint conditions. This review provides an update on the use of conventional radionuclide imaging tests and recent advancements in fusion imaging scans for the differential diagnosis of musculoskeletal infections. Furthermore, it examines the role of radionuclide scans in monitoring treatment responses and explores current trends in their application. We anticipate that this update will be of significant interest to internists, rheumatologists, radiologists, orthopedic surgeons, rehabilitation physicians, and other specialists involved in musculoskeletal pathology.

Imaging in spinal infections: Current status and future directions

Imaging plays an important role in the diagnosis of spinal infections. Early diagnosis is paramount in the treatment of spinal infections and leads to improved outcomes. This article reviews the imaging and relevant clinical details of infections of the spine: pyogenic spondylodiscitis, tuberculous spondylodiscitis, septic facet arthritis, epidural abscess, and subdural abscess. Though radiographs can reveal subtle changes with infections, advanced imaging modalities have increased sensitivity to aid in early diagnosis. Magnetic resonance imaging (MRI) is emphasized given it is generally the most sensitive and specific advanced imaging modality. However, nuclear medicine imaging and computer tomography (CT) play a role diagnosis in cases where MRI is not available or contra-indicated. Additionally, CT is also important for image-guided biopsy to guide antimicrobial treatment.

Understanding the management of pediatric spondylodiscitis based on existing literature; a systematic review

BACKGROUND

Spondylodiscitis (SD), a rare disease in children, poses diagnostic challenges due to non-specific presenting symptoms, scarcity in incidence, and difficulty expressing pain in non-verbal children.

METHOD

A comprehensive search was conducted on three databases, including PubMed/Medline, Web of Science, and Scopus until March 2023. The inclusion criteria were studies that investigated the clinical characteristics, treatment, and complications of children's spondylodiscitis. Full text of cross-sectional and cohort studies were added. The quality assessment of cohort studies was conducted using the Newcastle-Ottawa Quality Assessment Scale. The search, screening, and data extraction were performed by two researchers independently.

RESULT

Clinical manifestations of discitis in children are nonspecific, such as back pain, fever, reduced ability or inability to walk or sit, limping, and reduced range of movements. The mean delay in the time of diagnosis was 4.8 weeks. The most affected site of all the studies was the lumbar spine. 94% of studies reported increased inflammatory markers such as white blood cell count, C-reactive protein, and erythrocyte sedimentation rate. Less than 30% of patients had positive blood cultures and biopsy findings. The most common microbiological results (64%) were Staphylococcus Aureus and Kingella kingae. In radiographic evaluation, intervertebral disk narrowing, lumbar lordosis reduction, loss of disk height, and destruction of the vertebral body have been reported. In all studies, antibiotic therapy was initiated; in 52% immobilization was employed, and 29% of studies reported surgery was performed, and the follow-up period differed from 1.5 months to 156 months. 94% of studies reported complications such as vertebral body destruction, back pain, kyphosis, reduced range of movement, scoliosis, and neurological complications.

CONCLUSION

Spondylodiscitis is an uncommon, heterogeneous, multifactorial disease with resulting difficult and delayed diagnosis. Due to its morbidity, it is essential to investigate children with refusal to walk, gait disturbances, or back pain, particularly when associated with elevated inflammatory markers.

A Brief History of Nuclear Medicine Imaging of Infection

For nearly 50 years, nuclear medicine has played an important role in the diagnosis of infection. Gallium citrate Ga 67 was one of the first, if not the first, radionuclide used for this purpose. Unfavorable imaging characteristics, a lack of specificity, and the long interval (2-3 days) between administration and imaging spurred the search for alternatives. At the present time, gallium 67 citrate is used primarily for differentiating acute tubular necrosis from interstitial nephritis and as an alternative for indications including sarcoid, spondylodiscitis, and fever of unknown origin, when 18F-fluorodeoxyglucose (18F-FDG) is not available. The approval, in the mid-1980s, of techniques for in vitro labeling of leukocytes with indium-111 and technetium-99m that subsequently migrate to foci of infection was a significant advance in nuclear medicine imaging of infection and labeled leukocyte imaging still plays an important role in imaging of infection. There are significant disadvantages to in vitro labeled leukocyte imaging. Unfortunately, efforts devoted to developing in vivo leukocyte labeling methods have met with only limited success. Over the past 20 years 18F-FDG has established itself as a valuable imaging agent for musculoskeletal and cardiovascular infections, as well as sarcoidosis and fever of unknown origin. As useful as these agents are, their uptake is based on the host response to infection, not infection itself. Previous attempts at developing infection-specific agents, including radiolabeled antibiotics and vitamins, were limited by poor results and/or lack of availability, so investigators continue to focus on developing infection-specific nuclear medicine imaging agents.

Value of [18F]FDG PET/CT in Diagnosis and Management of Spondylodiscitis

Vertebral osteomyelitis is the third most common form of osteomyelitis in patients over 50 years of age.Whereas prompt (pathogen-directed) therapy is crucially associated with better outcomes, the heterogeneous clinical presentation of disease with unspecific symptoms often delays adequate treatment initiation. Diagnosis requires a careful investigation of medical history, clinical findings and diagnostic imaging, including magnetic resonance imaging and nuclear medicine techniques.Due to its high sensitivity, [18F]FDG PET/CT is becoming increasingly important in diagnosis and management of spondylodiscitis, especially in the postoperative setting with presence of spinal hardware or other implantable devices in which MRI is limited.

Update on Pediatric Spine Imaging

The spine is often difficult to evaluate clinically in children, increasing the importance of diagnostic imaging to detect a wide variety of spinal disorders ranging from congenital abnormalities to severe infections. Clinical history and physical examination can help determine whether imaging is needed and which imaging technique would be best. The most common cause for back pain, even in children, is muscular strain/spasm that does not require any imaging. However, red flags such as pain at age < 5 years, constant pain, night pain, radicular pain, pain lasting > 4 weeks, or an abnormal neurologic examination may require further investigation. Imaging can be of great value for diagnosis but must be interpreted along with the clinical history, physical examination, and laboratory findings to achieve an accurate diagnosis. We discuss imaging for the most common and/or important spine pathologies in children: congenital and developmental pathologies, trauma, infectious processes, inflammatory causes, and tumors.

Carbapenem-Resistant Pseudomonas aeruginosa Spondylodiscitis Treated with Ceftazidime-Avibactam: A Case Report with Literature Review

Pyogenic spondylodiscitis (PS) is a highly morbid and potentially fatal bacterial infection with an increasing incidence in recent decades. Its diagnosis and treatment are challenging, especially with the expansion of multidrug- or extensively drug-resistant bacteria. We report a rare case of PS caused by carbapenem-resistant Pseudomonas aeruginosa (CRPA) that was treated with ceftazidime-avibactam (C/A). The choice of C/A therapy was based on the patient's bacterial sensitivity profile and intolerance to the initial therapeutic regimen (polymyxin B and meropenem). The total antimicrobial treatment time was seven weeks. The evolution of the clinical course met the cure criteria, which was characterized by remission of signs and symptoms, normalization of inflammatory markers, and radiological improvement over 18 months of clinical follow-up. This is a rare case of CRPA spondylodiscitis that responded to C/A treatment.

Risk Factors for the In-Hospital Mortality in Pyogenic Vertebral Osteomyelitis: A Cross-Sectional Study on 9753 Patients

BACKGROUND

Pyogenic vertebral osteomyelitis represents a clinical challenge associated with significant morbidity and mortality. The aim of this study was to analyze potential risk factors for the in-hospital mortality of vertebral osteomyelitis (VO) patients.

METHODS

Based on the International Classification of Diseases, 10th Revision (ICD-10) codes for VO ("M46.2-", "M46.3-", and "M46.4-") data for total case numbers, secondary diagnoses, and numbers of in-hospital deaths were extracted from the Institute for the Hospital Remuneration System (InEK GmbH). Odds ratios (OR) for death were calculated for several secondary diseases and factors of interest.

RESULTS

Despite age, certain comorbidities were found to be strongly associated with increased mortality risk: Heart failure (OR = 2.80; 95% CI 2.45 to 3.20; p < 0.01), chronic kidney disease (OR = 1.83; 95% CI 1.57 to 2.13; p < 0.01), and diabetes with complications (OR = 1.86; 95% CI 1.46 to 2.38; p < 0.01). Among the complications, acute liver failure showed the highest risk for in-hospital mortality (OR = 42.41; 95% CI 23.47 to 76.62; p < 0.01). Additionally, stage III kidney failure (OR = 9.81; 95% CI 7.96 to 12.08; p < 0.01), sepsis (OR = 5.94; 95% CI 5.02 to 7.03; p < 0.01), acute respiratory failure (OR = 5.31; 95% CI 4.61 to 6.12; p < 0.01), and systemic inflammatory response syndrome (SIRS) (OR = 5.19; 95% CI 3.69 to 5.19; p < 0.01) were associated with in-hospital mortality. When analyzing the influence of pathogens, documented infection with Pseudomonas aeruginosa had the highest risk for mortality (OR = 2.74; 95% CI 2.07 to 3.63; p < 0.01), followed by Streptococci, Escherichia coli, and Staphylococcus aureus infections.

CONCLUSIONS

An early assessment of individual patient risk factors may be beneficial in the care and treatment of VO to help reduce the risks of mortality. These findings emphasize the importance of closely monitoring VO patients with chronic organ diseases, early detection and treatment of sepsis, and tailored empirical antibiotic therapy. The identification of specific pathogens and antibiotic susceptibility testing should be prioritized to improve patient outcomes in this high-risk population.

Value of [18F]FDG PET/CT in diagnosis and management of spondylodiscitis

Vertebral osteomyelitis is the third most common form of osteomyelitis in patients over 50 years of age.Whereas prompt (pathogen-directed) therapy is crucially associated with better outcomes, the heterogeneous clinical presentation of disease with unspecific symptoms often delays adequate treatment initiation. Diagnosis requires a careful investigation of medical history, clinical findings and diagnostic imaging, including magnetic resonance imaging and nuclear medicine techniques.Due to its high sensitivity, [¹⁸F]FDG PET/CT is becoming increasingly important in diagnosis and management of spondylodiscitis, especially in the postoperative setting with presence of spinal hardware or other implantable devices in which MRI is limited.

The Epidemiology of Spondylodiscitis in Germany: A Descriptive Report of Incidence Rates, Pathogens, In-Hospital Mortality, and Hospital Stays between 2010 and 2020

BACKGROUND

Spondylodiscitis can lead to significant morbidity and mortality. Understanding its up-to-date epidemiological characteristics and trends is important to improve patient care.

METHODS

This study analyzed trends in the incidence rate of spondylodiscitis cases in Germany between 2010 and 2020, as well as the pathogens, in-hospital mortality rate, and length of hospital stay. Data were obtained from the Federal Statistical Office and the Institute for the Hospital Remuneration System database. The ICD-10 codes "M46.2-", "M46.3-" and "M46.4-" were evaluated.

RESULTS

The incidence rate of spondylodiscitis increased to 14.4/100,000 inhabitants, with 59.6% cases occurring in patients 70 years or older and affecting mainly the lumbar spine (56.2%). Absolute case numbers increased from 6886 by 41.6% to 9753 in 2020 (IIR = 1.39, 95% CI 0.62-3.08). Staphylococci and Escherichia coli were the most coded pathogens. The proportion of resistant pathogens was 12.9%. In-hospital mortality rates increased to a maximum of 64.7/1000 patients in 2020, intensive care unit treatment was documented in 2697 (27.7%) cases, and the length of stay per case was 22.3 days.

CONCLUSION

The sharply increasing incidence and in-hospital mortality rate of spondylodiscitis highlights the need for patient-centered therapy to improve patient outcomes, especially in the geriatric, frail population, which is prone to infectious diseases.

Diagnostic accuracy of fluorine-18 fluorodeoxyglucose positron emission tomography for suspected primary and postoperative pyogenic spondylitis

OBJECTIVE

Fluorine-18 fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET) and PET/CT have been suggested for confirming or excluding musculoskeletal infection but the diagnostic value of this tool for pyogenic spondylitis remains to be confirmed. This meta-analysis was performed to verify the accuracy of ¹⁸F-FDG PET and PET/CT in diagnosing suspected pyogenic spondylitis by performing a systematic review and meta-analysis.

METHODS

We conducted a comprehensive literature search of PubMed, Embase and Cochrane Library to retrieve diagnostic accuracy studies in which suspected pyogenic spondylitis was assessed with ¹⁸F-FDG PET or PET/CT. The pooled sensitivity, specificity, likelihood ratios, diagnostic odds ratio (DOR), summarized receiver operating characteristic curve (sROC) and the area under the sROC (AUC) were calculated by using Stata software.

RESULTS

A total of 18 eligible studies (660 patients) with suspected pyogenic spondylitis were included in the quantitative analysis. ¹⁸F-FDG PET and PET/CT illustrated relatively high sensitivity (0.91, 95% CI: 0.84-0.95) and specificity (0.90, 95% CI: 0.79-0.95) for the diagnosis of pyogenic spondylitis. The pooled DOR and AUC were 86.00 (95% CI, 31.00-240.00) and 0.96 (95% CI, 0.94-0.97), respectively. For diagnosing pyogenic spondylitis without previous spine surgery, the pooled sensitivity, specificity, DOR and AUC were 0.93 (95% CI, 0.85-0.97), 0.91 (95% CI, 0.77-0.97), 136 (95% CI, 35-530) and 0.97 (95% CI, 0.95-0.98), respectively. For diagnosing postoperative pyogenic spondylitis, the pooled sensitivity, specificity, DOR and AUC were 0.85 (95% CI, 0.71 to 0.93), 0.87 (95% CI, 0.66 to 0.96), 38 (95% CI, 9 to 167) and 0.92 (95% CI, 0.89 to 0.94), respectively.

CONCLUSION

¹⁸F-FDG PET and PET/CT presented satisfactory accuracy for diagnosing pyogenic spondylitis. The diagnostic effect of this nuclear imaging method for pyogenic spondylitis without previous spine surgery seems to be better than that for the postoperative ones. However, whether ¹⁸F-FDG PET and PET/CT could become a routine in patients with suspected pyogenic spondylitis remains to be confirmed.

LEVEL OF EVIDENCE

Level I evidence, a summary of meta-analysis.

A Predictive Clinical-Radiomics Nomogram for Differentiating Tuberculous Spondylitis from Pyogenic Spondylitis Using CT and Clinical Risk Factors

OBJECTIVE

The study aimed to develop and validate a nomogram model with clinical risk factors and radiomic features for differentiating tuberculous spondylitis (TS) from pyogenic spondylitis (PS).

METHODS

A total of 254 patients with TS (n = 141) or PS (n = 113) were randomly divided into training (n = 180) and validation (n = 74) groups. In addition, 43 patients (TS = 22 and PS = 21) were collected to construct a test cohort. t-test analysis, de-redundancy analysis, and minimum absolute shrinkage and selection operator (lasso) algorithm were utilized on the training set to obtain the optimal radiomics features from computed tomography (CT) for constructing the radiomics model and determine the radiomics score (Rad-score). Eight clinical risk predictors were identified to develop the clinical model. Combined with clinical risk predictors and Rad-scores, a nomogram model was constructed using multivariate logistic regression analysis.

RESULTS

A total of 1781 features were extracted, and 12 optimal radiomic features were utilized to construct the radiomic model and determine the Rad-score. The combined clinical radiomics model revealed good discrimination performance in both the training cohort and the validation cohort (AUC = 0.891 and 0.830) and was superior to the clinical (AUC = 0.807 and 0.785) and radiomics (AUC = 0.796 and 0.811) models. The calibration curve and DCA also depicted that the nomogram had better clinical efficacy. The discriminative performance of the model is well validated in the test cohort (AUC=0.877).

CONCLUSION

The clinical radiomic nomogram could serve as a promising predictive tool for differentiating TS from PS, which could be helpful for clinical decision-making.

Intervertebral disc cell chondroptosis elicits neutrophil response in Staphylococcus aureus spondylodiscitis

To understand the pathophysiology of spondylodiscitis due to Staphylococcus aureus, an emerging infectious disease of the intervertebral disc (IVD) and vertebral body with a high complication rate, we combined clinical insights and experimental approaches. Clinical data and histological material of nine patients suffering from S. aureus spondylodiscitis were retrospectively collected at a single center. To mirror the clinical findings experimentally, we developed a novel porcine ex vivo model mimicking acute S. aureus spondylodiscitis and assessed the interaction between S. aureus and IVD cells within their native environment. In addition, the inflammatory features underlying this interaction were assessed in primary human IVD cells. Finally, mirroring the clinical findings, we assessed primary human neutrophils for their ability to respond to secreted inflammatory modulators of IVD cells upon the S. aureus challenge. Acute S. aureus spondylodiscitis in patients was characterized by tissue necrosis and neutrophil infiltration. Additionally, the presence of empty IVD cells’ lacunae was observed. This was mirrored in the ex vivo porcine model, where S. aureus induced extensive IVD cell death, leading to empty lacunae. Concomitant engagement of the apoptotic and pyroptotic cell death pathways was observed in primary human IVD cells, resulting in cytokine release. Among the released cytokines, functionally intact neutrophil-priming as well as broad pro- and anti-inflammatory cytokines which are known for their involvement in IVD degeneration were found. In patients as well as ex vivo in a novel porcine model, S. aureus IVD infection caused IVD cell death, resulting in empty lacunae, which was accompanied by the release of inflammatory markers and recruitment of neutrophils. These findings offer valuable insights into the important role of inflammatory IVD cell death during spondylodiscitis and potential future therapeutic approaches.

Discitis due to late-onset mesh infection 14 years after inguinal hernia repair: a case report

BACKGROUND

Mesh infection after inguinal hernia repair is a very rare complication. The incidence of late-onset mesh infection is approximately 0.1-0.2% of total hernia repair cases and can lead to serious complications if not treated promptly. Here, we report a rare case of discitis due to late-onset mesh infection, occurring 14 years after an inguinal hernia repair.

CASE PRESENTATION

An 89-year-old man was brought to our hospital with right-sided abdominal pain and signs of hypoglycemia. He had a history of type 2 diabetes mellitus and had undergone inguinal hernia repair 14 years ago. Upon admission, laboratory tests revealed no elevated inflammatory markers. Computed tomography (CT) revealed a peri-appendicular abscess. Although the patient was administered empiric antibiotics, on day 3 of admission, his white blood cell count and C-reactive protein levels increased to 38,000/µl and 28 mg/dl, respectively. CT-guided drainage was attempted but was not successful. Escherichia coli was detected in both blood culture collections. On day 7 of admission, the patient complained of back pain; CT on day 10 revealed a peri-appendicular abscess with a soft tissue shadow anterior to the thoracic vertebrae at the 8th/9th level. Thoracic discitis, due to bacteremia originating from the mesh abscess, was suspected. We surgically resected the appendix, followed by removal of the plug and mesh abscess. The post-operative course of the patient was uneventful. For treating discitis, it is known that antibiotic therapy is required for a minimum of 6 weeks. Therefore, on the 30th day post-surgery, the patient was transferred to the orthopedic ward for continued treatment.

CONCLUSIONS

This report discusses a rare case of late-onset mesh infection leading to thoracic discitis. Since late-onset mesh infection cannot be treated solely with antibiotics, expeditious surgery should be selected when subcutaneous drainage fails. When an immunocompromised patient with bacteremia has a complaint of back pain, purulent spinal discitis should also be suspected.

A Case of Spondylodiscitis Fistulating Into the Vagina 15 Years after Promontofixation

Promontofixations can be a rare cause of spondylodiscitis due to the material used getting infected. We present here a case of a 75-year-old woman who underwent a subtotal hysterectomy, followed by a trachelectomy, and presented 15 years later with lumbago and fever. After thorough examination, haemocultures and imaging were performed. This led to the diagnosis of spondylodiscitis of L5-S1, likely due to S. constellatus, with a fistula into the vagina. The patient received surgical treatment. This case is unusual due to the time lapse between the hysterectomy and the infection as well as the probable pathogen.

Teaching Point: Promontofixation material can remain despite hysterectomy and can be a source of infection many years after the operation has taken place.

Isolation of Brucella melitensis from Lumbar Vertebrae in Patient with Initial Misdiagnosis: A Rare Case with Spinal Epidural Abscess, Spinal Stenosis, and Brain Lesion

Introduction: Brucellar spondylodiscitis is among the most typical forms of osteoarticular involvement that still challenges clinicians and scientists for early diagnosis. Case Presentation: We describe the isolation of Brucella melitensis from vertebrae in a man with spondylodiscitis who had osteoarthritis as an underlying condition. The patient showed negative results on blood samples' serological, molecular, and culture tests and had low-back pain, restricted lumbar movements, headache, poor appetite, and fatigue for the past nine months. He had a history of regular ingestion of raw cow milk and milk products for a long time. First, he was misdiagnosed as lumbar disc herniation and then underwent nonsteroidal anti-inflammatory drugs and myorelaxants treatment. The lack of fast diagnosis and appropriate treatment led to severe complications of the disease. Three months after the first magnetic resonance imaging (MRI), the findings of the second MRI without intravenous contrast showed right lateral recess and canal stenosis at L4 - L5 with narrowing the thecal sac at the disc space. Abnormal enhancement of the endplates at L4 - L5 with relating epidural space-enhancing tissue in the setting of spondylodiscitis and the associated epidural abscess was seen behind L4. Moreover, extensive high signal abnormalities in paraspinal tissues at L3, L4, L5, S1, S2, and S3 were notable. The diagnosis was approved by isolating B. melitensis biovar 1 from the culture of the vertebrate body. The Brucella isolate was characterized by Bruce-ladder PCR, AMOS PCR, and classical biotyping. The patient was treated successfully with surgical intervention and triple-antibiotic, including oral doxycycline 100 mg/12 h plus oral rifampin 300 mg/12 h for three months and intramuscular streptomycin 1 g daily for the first two weeks. The patient’s general condition and low-back pain were remarkably improved in the follow-up. Conclusions: Patient histories and a series of different diagnostic procedures such as MRI, serology, molecular, and cultural tests are essential to make a rapid and accurate diagnosis of brucellar spondylodiscitis, thereby reducing the delay for brucellar spondylodiscitis treatment.

MRI Features Associated With the Detection of Microbial Pathogens by CT-Guided Biopsy in Septic Spondylodiscitis

OBJECTIVE

The aim of this study was to assess the magnetic resonance imaging (MRI) features associated with microbial pathogen detection by computed tomography (CT)-guided biopsy in patients with suspected septic spondylodiscitis.

METHODS

For the last 10-year period, we analyzed the medical records of patients who underwent MRI and CT-guided biopsy for suspected septic spondylodiscitis. Clinical characteristics were recorded. The following MRI features were assessed: edema or contrast enhancement of the intervertebral disc, adjacent vertebrae, epidural and paravertebral space, presence of abscess, and paravertebral edema size. A positive biopsy was defined by pathogen identification on bacterial analysis or the presence of granuloma on histology. Predictors of a positive biopsy were assessed with a logistic regression model.

RESULTS

We examined data for 61 patients (34 [56%] male; mean age, 59.9 ± 18.0 years); for 35 patients (57%), CT-guided biopsy was positive for a pathogen. The 4 MRI findings significantly associated with a positive biopsy were epiduritis, greater than 50% vertebral endplate edema, loss of intradiscal cleft, and abscess. The size of paravertebral edema was greater with a positive than negative biopsy (median, 15.9 [interquartile range, 11.3-21.3] vs 7.3 [4.6-12.9] mm; p = 0.004). On multivariable analysis, epiduritis was the only independent predictor of a positive biopsy (adjusted odds ratio, 7.4 [95% confidence interval, 1.7-31.4]; p = 0.006).

CONCLUSIONS

Epiduritis and the size of paravertebral edema on MRI are associated with detection of a microbial pathogen in suspected septic spondylodiscitis. For patients without these MRI signs, the need for further investigations such as enriched or prolonged cultures, a second CT-guided biopsy, or even surgical biopsy need to be discussed.

MORPHOLOGICAL ASPECT OF PYOGENIC SPINAL EPIDURAL ABSCESSES. PART I

ABSTRACT Background: Pyogenic Spinal Epidural Abscess (PSEA) is difficult to diagnose and can have devastating consequences. Magnetic Resonance Imaging (MRI) has high sensitivity and specificity, which are further increased with the use of contrast. There are several classifications of vertebral infectious processes, with emphasis on spondylodiscitis. Objective: To analyze the morphological parameters and their reproducibility; and to analyze different resonance imaging sequences. Methods: Using an image database, a morphological classification of PSEA was planned, with five parameters: Region (R), indicating the upper and lower limits of the abscess; Location (U), indicating whether the abscess is anterior or posterior within the canal; Compromise (C), meningeal or content of the structures; Association (A), discitis, osteomyelitis or both; and Perivertebral (P), anterior, lateral or posterior extravertebral abscess. The first three parameters give an idea of the volume of the PSEA, while the last two give the related infectious foci. Thirty-five cases were analyzed using Kappa’s coefficient. Results: The global intra- and interobserver reproducibility was Kappa 0.81. The results for each parameter were as follows: R=0.95, U=0.92, C=0.66, A=0.70 and P=0.80. The first three give a notion of volume and the last two relate to the presence of vertebral infectious foci outside the canal. T2 weighted MRI with contrast was found to be the most effective imaging sequence. Conclusion: The morphological classification is simple to use, with excellent reproducibility. The parameters with the highest reproducibility were region and location, with values >0.92. The addition of gadolinium contrast increased the sensitivity of the diagnosis; the use of sagittal and axial images in T2-MRI was the most sensitive imaging sequence. Evidence Level III; Original.

Proton Density Fat Fraction Spine MRI for Differentiation of Erosive Vertebral Endplate Degeneration and Infectious Spondylitis

Vertebral Modic type 1 (MT1) degeneration may mimic infectious disease on conventional spine magnetic resonance imaging (MRI), potentially leading to additional costly and invasive investigations. This study evaluated the diagnostic performance of the proton density fat fraction (PDFF) for distinguishing MT1 degenerative endplate changes from infectious spondylitis. A total of 31 and 22 patients with equivocal diagnosis of MT1 degeneration and infectious spondylitis, respectively, were retrospectively enrolled in this IRB-approved retrospective study and examined with a chemical-shift encoding (CSE)-based water-fat 3D six-echo modified Dixon sequence in addition to routine clinical spine MRI. Diagnostic reference standard was established according to histopathology or clinical and imaging follow-up. Intravertebral PDFF [%] and PDFFratio (i.e., vertebral endplate PDFF/normal vertebrae PDFF) were calculated voxel-wise within the single most prominent edematous bone marrow lesion per patient and examined for differences between MT1 degeneration and infectious spondylitis. Mean PDFF and PDFFratio of infectious spondylitis were significantly lower compared to MT1 degenerative changes (mean PDFF, 4.28 ± 3.12% vs. 35.29 ± 17.15% [p < 0.001]; PDFFratio, 0.09 ± 0.06 vs. 0.67 ± 0.37 [p < 0.001]). The areas under the curve (AUC) and diagnostic accuracies were 0.977 (p < 0.001) and 98.1% (cut-off at 12.9%) for PDFF and 0.971 (p < 0.001) and 98.1% (cut-off at 0.27) for PDFFratio. Our data suggest that quantitative evaluation of vertebral PDFF can provide a high diagnostic accuracy for differentiating erosive MT1 endplate changes from infectious spondylitis.

Spinal disorders mimicking infection

Spinal infections are very commonly encountered by radiologists in their routine clinical practice. In case of typical MRI features, the diagnosis is relatively easy to interpret, all the more so if the clinical and laboratory findings are in agreement with the radiological findings. In many cases, the radiologist is able to make the right diagnosis, thereby avoiding a disco-vertebral biopsy, which is technically challenging and associated with a risk of negative results. However, several diseases mimic similar patterns, such as degenerative changes (Modic) and crystal-induced discopathy. Differentiation between these diagnoses relies on imaging changes in endplate contours as well as in disc signal. This review sought to illustrate the imaging pattern of spinal diseases mimicking an infection and to define characteristic MRI and CT patterns allowing to distinguish between these different disco-vertebral disorders. The contribution of advanced techniques, such as DWI and dual-energy CT (DECT) is also discussed.

ACR Appropriateness Criteria® Suspected Spine Infection

Spine infection is both a clinical and diagnostic imaging challenge due to its relatively indolent and nonspecific clinical presentation. The diagnosis of spine infection is based upon a combination of clinical suspicion, imaging evaluation and, when possible, microbiologic confirmation performed from blood cultures or image-guided percutaneous or open spine biopsy. With respect to the imaging evaluation of suspected spine infection, MRI without and with contrast of the affected spine segment is the initial diagnostic test of choice. As noncontrast MRI of the spine is often used in the evaluation of back or neck pain not responding to conservative medical management, it may show findings that are suggestive of infection, hence this procedure may also be considered in the evaluation of suspected spine infection. Nuclear medicine studies, including skeletal scintigraphy, gallium scan, and FDG-PET/CT, may be helpful in equivocal or select cases. Similarly, radiography and CT may be appropriate for assessing overall spinal stability, spine alignment, osseous integrity and, when present, the status of spine instrumentation or spine implants. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Imaging update on musculoskeletal infections

The clinical diagnosis of musculoskeletal infections can be challenging due to non-specific signs and symptoms on presentation. These infections include infectious myositis, necrotising fasciitis, septic arthritis, septic bursitis, suppurative tenosynovitis, osteomyelitis, spondylodiscitis and periprosthetic infections. Diagnostic imaging is routinely employed as part of the investigative pathway to characterise the underlying infectious disease pattern, allowing expedited and customised patient management plans to optimise outcomes. This article provides an update on the various imaging modalities comprising of radiography, computed tomography, ultrasonography, magnetic resonance imaging and radionuclide procedures, and incorporates representative images of key findings in the different forms of musculoskeletal infections.

Axial Spondyloarthritis: Mimics and Pitfalls of Imaging Assessment

Axial spondyloarthritis (axSpA) is a chronic inflammatory disorder that predominantly involves the axial skeleton. Imaging findings of axSpA can be divided into active changes, which include bone marrow edema, synovitis, enthesitis, capsulitis, and intra-articular effusion, and structural changes, which include erosions, sclerosis, bone fatty infiltration, fat deposition in an erosion cavity, and bone bridging or ankylosis. The ability to distinguish between imaging lesions suggestive of axSpA and artifacts or lesions suggestive of other disorders is critical for the accurate diagnosis of axSpA. Diagnosis may be challenging, particularly in early-stage disease and magnetic resonance imaging (MRI) plays a key role in the detection of subtle or inflammatory changes. MRI also allows the detection of structural changes in the subchondral bone marrow that are not visible on conventional radiography and is of prognostic and monitoring value. However, bone structural changes are more accurately depicted using computed tomography. Conventional radiography, on the other hand, has limitations, but it is easily accessible and may provide insight on gross changes as well as rule out other pathological features of the axial skeleton. This review outlines the imaging evaluation of axSpA with a focus on imaging mimics and potential pitfalls when assessing the axial skeleton.

Is 67gallium dead? A retrospective review of 67gallium imaging in a single tertiary referral centre

BACKGROUND

[67Ga]Ga-citrate scanning has been used to investigate patients with known or suspected infection for over 50 years, continuing to maintain a clinical niche in many centres. The introduction of single photon emission tomography/computed tomography (SPECT/CT) in addition to planar imaging has improved the specificity of diagnosis.

AIM

To examine the experience of modern [67Ga]Ga-citrate scanning in a single tertiary referral centre, considering the diagnostic yield of the study.

METHODS

A retrospective audit was undertaken of 100 consecutive [67Ga]Ga-citrate scans at Royal North Shore Hospital, Sydney. Recorded information included patient demographics, clinical information/history, and primary and secondary diagnoses. Subgroup analyses included patients with a confirmed diagnosis of infection or a suspected diagnosis of infection.

RESULTS

The median age of patients was 68.5 years. Totally, 39/100 patients undergoing [67Ga]Ga-citrate scanning presented with a confirmed site of infection, with 2/6 patients with infective endocarditis and 5/12 patients with bacteraemia diagnosed with an additional, previously unknown, site of active infection (compared to 1/21 patients without documented bacteraemia). 61/100 patients did not have a confirmed site of infection before [67Ga]Ga-citrate scan (as per clinical history). 34/61 of these patients had a positive scan result for active infection/inflammation. Of 20 patients with a positive blood culture but no suspected site of infection, the source was identified in 9.

CONCLUSION

[67Ga]Ga-citrate has diagnostic value in the evaluation of complex patients with high-risk infection. High diagnostic yield is demonstrated in patients with bacteraemia with or without a confirmed site of infection, particularly when combined with SPECT/CT.

A diagnostic model for differentiating tuberculous spondylitis from pyogenic spondylitis on computed tomography images

OBJECTIVES

To develop and evaluate a logistics regression diagnostic model based on computer tomography (CT) features to differentiate tuberculous spondylitis (TS) from pyogenic spondylitis (PS).

METHODS

Demographic and clinical features were collected from the Electronic Medical Record System. Data of bony changes seen on CT images were compared between the PS (n = 61) and TS (n = 51) groups using the chi-squared test or t test. Based on features that were identified to be significant, a diagnostic model was developed from a derivation set (two thirds) and evaluated in a validation set (one third). The sensitivity, specificity, and area under the receiver operating characteristic curve (AUC) were calculated.

RESULTS

The width of bone formation around the vertebra and sequestrum was greater in the TS group. There were significant differences between the two groups in the horizontal and longitudinal location of erosion and the morphology of axial bone destruction and sagittal residual vertebra. Kyphotic deformity and overlapping vertebrae were more common in the TS group. A diagnostic model that included eight predictors was developed and simplified to include the following six predictors: width of the bone formation surrounding the vertebra, longitudinal location, axial-specific erosive morphology, specific morphology of the residual vertebra, kyphotic deformity, and overlapping vertebrae. The simplified model showed good sensitivity, specificity, and total accuracy (85.59%, 87.80%, and 86.50%, respectively); the AUC was 0.95, indicating good clinical predictive ability.

CONCLUSIONS

A diagnostic model based on bone destruction and formation seen on CT images can facilitate clinical differentiation of TS from PS.

KEY POINTS

• We have developed and validated a simple diagnostic model based on bone destruction and formation observed on CT images that can differentiate tuberculous spondylitis from pyogenic spondylitis. • The model includes six predictors: width of the bone formation surrounding the vertebra, longitudinal location, axial-specific erosive morphology, specific morphology of the residual vertebra, kyphotic deformity, and overlapping vertebrae. • The simplified model has good sensitivity, specificity, and total accuracy with a high AUC, indicating excellent predictive ability.

State of the art of 18F-FDG PET/CT application in inflammation and infection: a guide for image acquisition and interpretation

AIM

The diagnosis, severity and extent of a sterile inflammation or a septic infection could be challenging since there is not one single test able to achieve an accurate diagnosis. The clinical use of 18F-fluorodeoxyglucose ([¹⁸F]FDG) positron emission tomography/computed tomography (PET/CT) imaging in the assessment of inflammation and infection is increasing worldwide. The purpose of this paper is to achieve an Italian consensus document on [¹⁸F]FDG PET/CT or PET/MRI in inflammatory and infectious diseases, such as osteomyelitis (OM), prosthetic joint infections (PJI), infective endocarditis (IE), prosthetic valve endocarditis (PVE), cardiac implantable electronic device infections (CIEDI), systemic and cardiac sarcoidosis (SS/CS), diabetic foot (DF), fungal infections (FI), tuberculosis (TBC), fever and inflammation of unknown origin (FUO/IUO), pediatric infections (PI), inflammatory bowel diseases (IBD), spine infections (SI), vascular graft infections (VGI), large vessel vasculitis (LVV), retroperitoneal fibrosis (RF) and COVID-19 infections.

METHODS

In September 2020, the inflammatory and infectious diseases focus group (IIFG) of the Italian Association of Nuclear Medicine (AIMN) proposed to realize a procedural paper about the clinical applications of [¹⁸F]FDG PET/CT or PET/MRI in inflammatory and infectious diseases. The project was carried out thanks to the collaboration of 13 Italian nuclear medicine centers, with a consolidate experience in this field. With the endorsement of AIMN, IIFG contacted each center, and the pediatric diseases focus group (PDFC). IIFG provided for each team involved, a draft with essential information regarding the execution of [¹⁸F]FDG PET/CT or PET/MRI scan (i.e., indications, patient preparation, standard or specific acquisition modalities, interpretation criteria, reporting methods, pitfalls and artifacts), by limiting the literature research to the last 20 years. Moreover, some clinical cases were required from each center, to underline the teaching points. Time for the collection of each report was from October to December 2020.

RESULTS

Overall, we summarized 291 scientific papers and guidelines published between 1998 and 2021. Papers were divided in several sub-topics and summarized in the following paragraphs: clinical indications, image interpretation criteria, future perspectivess and new trends (for each single disease), while patient preparation, image acquisition, possible pitfalls and reporting modalities were described afterwards. Moreover, a specific section was dedicated to pediatric and PET/MRI indications. A collection of images was described for each indication.

CONCLUSIONS

Currently, [¹⁸F]FDG PET/CT in oncology is globally accepted and standardized in main diagnostic algorithms for neoplasms. In recent years, the ever-closer collaboration among different European associations has tried to overcome the absence of a standardization also in the field of inflammation and infections. The collaboration of several nuclear medicine centers with a long experience in this field, as well as among different AIMN focus groups represents a further attempt in this direction. We hope that this document will be the basis for a "common nuclear physicians' language" throughout all the country.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s40336-021-00445-w.

Tuberculous and Brucellar Spondylodiscitis: Comparative Analysis of Clinical, Laboratory, and Radiological Features

Study Design

This was a retrospective study.

Purpose

The aim was to compare the clinical, laboratory, radiological, and evolutionary features of tuberculous spondylodiscitis (TS) and brucellar spondylodiscitis (BS).

Overview of Literature

Clinical presentation of spondylodiscitis varies according to the underlying etiology, among which brucellosis and tuberculosis represent the primary cause, in endemic countries. Only a few studies have compared the characteristics between TS and BS.

Methods

A retrospective study was conducted using the data of all patients hospitalized for TS and BS in the infectious diseases department between 1991 and 2018.

Results

Among a total of 117 patients, 73 had TS (62.4%) and 44 had BS (37.6%). Females were significantly more affected with TS than males (56.2% vs. 22.7%, p<0.001). Fever (72.7% vs. 45.2%, p=0.004) and sweating (72.7% vs. 47.9%, p=0.009) were significantly more frequent among patients with BS. The median erythrocyte sedimentation rate was significantly higher in the TS group (median, 70 mm/hr; interquartile range [IQR], 45–103 mm/hr) than in the BS group (median, 50 mm/hr; IQR, 16–75 mm/hr) (p=0.003). Thoracic involvement was significantly more frequent in the TS group (53.4% vs. 34.1%, p=0.04), whereas lumbar involvement was significantly more frequent in the BS group (72.7% vs. 49.3%, p=0.01). Initial imaging findings revealed significantly higher frequencies of posterior vertebral arch involvement, vertebral compaction, and spinal cord compression in the TS group. Percutaneous abscess drainage (20.5% vs. 2.3%, p=0.005) and surgical treatment (17.8% vs. 2.3%, p=0.01) were more frequently indicated in the TS group, with a significant difference.

Conclusions

A combination of clinical, laboratory, and radiological features can be used to distinguish between TS and BS while these patients await diagnosis confirmation.

The needle and the damage done: musculoskeletal and vascular complications associated with injected drug use

Injected drug use is associated with a wide range of medical complications which are predominantly musculoskeletal and vascular in nature. Illicit drug use is increasing worldwide. Patients with complications of injected drug use often present in a non-specific manner without a reliable clinical history. Musculoskeletal complications are typically infective in aetiology and may vary widely in severity from mild to life-threatening. A multimodal imaging approach is often required for both diagnostic imaging and image-guided sampling. Plain radiographs are often an important initial test, for example in identifying retained needles from injection. Ultrasound and CT play important roles in the assessment of complex soft tissue complications and MRI is the imaging modality of choice for bone and joint disorders. Vascular complications may be venous or arterial in nature and usually occur locally at the injection site. These complications may be related to direct injury to the vessel wall by a needle, or secondary to local infection and inflammation. A multimodal imaging strategy is also often required in the assessment of these vascular complications, typically involving a combination of ultrasound and CT. Familiarity with the multimodal imaging features of the complications related to injected drug use is crucially important as they may be rapidly progressive and life-threatening and require timely diagnosis.

Comparison of the Diagnostic Value of MRI and Whole Body 18F-FDG PET/CT in Diagnosis of Spondylodiscitis

Spondylodiscitis is a spine infection for which a diagnosis by a magnetic resonance imaging (MRI) is considered the most appropriate imaging technique. The aim of this study was to compare the role of an ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) and an MRI in this field. For 56 patients with suspected spondylodiscitis for whom MRI and ¹⁸F-FDG PET/CT were performed, we retrospectively analyzed the results. Cohen’s κ was applied to evaluate the agreement between the two techniques in all patients and in subgroups with a different number of spinal districts analyzed by the MRI. Sensitivity, specificity, and accuracy were also evaluated. The agreements of the ¹⁸F-FDG PET/CT and MRI in the evaluation of the entire population, whole-spine MRI, and two-districts MRI were moderate (κ = 0.456, κ = 0.432, and κ = 0.429, respectively). In patients for whom one-district MRI was performed, ¹⁸F-FDG PET/CT and MRI were both positive and completely concordant (κ = 1). We also separately evaluated patients with suspected spondylodiscitis caused by Mycobacterium tuberculosis for whom the MRI and ¹⁸F-FDG PET/CT were always concordant excepting in 2 of the 18 (11%) patients. Sensitivity, specificity, and accuracy of the MRI and ¹⁸F-FDG PET/CT were 100%, 60%, 97%, and 92%, 100%, and 94%, respectively. Our results confirmed the ¹⁸F-FDG PET/CT diagnostic value in the diagnosis of spondylodiscitis is comparable to that of MRI for the entire spine evaluation. This could be considered a complementary technique or a valid alternative to MRI.

Vertebral Bone Marrow and Endplate Assessment on MR Imaging for the Differentiation of Modic Type 1 Endplate Changes and Infectious Spondylodiscitis

On magnetic resonance (MR) imaging, Modic type 1 (MT1) endplate changes and infectious spondylodiscitis share similar findings. Therefore, this study investigated vertebral bone marrow and endplate changes to enable their differentiation. The lumbar spine MR examinations of 91 adult patients were retrospectively included: 39 with MT1; 19 with early spondylodiscitis without abscess; and 33 with advanced spondylodiscitis with abscess. The assessment included percentage of bone marrow edema on sagittal short tau inversion recovery images, and the signal ratio of edema to unaffected bone and endplate contour (normal; irregular, yet intact; blurred; destructive) on sagittal unenhanced T1-weighted images. Differences were tested for statistical significance by Chi-square test and mixed model analysis of variance. The MR diagnostic accuracy in differentiating MT1 and spondylodiscitis was assessed by cross-tabulation and receiver-operating characteristic analysis. The endplate contours, edema extents, and T1-signal ratios of MT1 (extent, 31.96%; ratio, 0.83) were significantly different (p < 0.001) from early spondylodiscitis (56.42%; 0.60), and advanced spondylodiscitis (91.84%; 0.61). The highest diagnostic accuracy (sensitivity, 94.87%; specificity, 94.23%; accuracy, 94.51%) in identifying MT1 was provided by an irregular, yet intact endplate contour. This may be a useful MR feature for the differentiation between MT1 and spondylodiscitis, particularly in its early stage.

Crowned dens syndrome: a neurologist's perspective

Crowned dens syndrome is an under-recognized entity that can mimic neurological disease, in particular meningitis or giant-cell arteritis. We present a 48-year-old woman presenting with an inflammatory meningitis-like syndrome with headache and neck stiffness. Lumbar puncture was normal and computed tomography (CT) of the atlantoaxial joint showed abnormal calcifications around the odontoid process, leading to a tentative diagnosis of crowned dens syndrome. In addition, signs of active inflammation in and around the dens were present on cervical MR imaging. Since CDS can mimic meningitis or giant-cell arteritis, neurologists should be aware of this entity. If CDS is suspected, the bone window on the head CT scan can lead to the diagnosis. On the other hand, asymptomatic periodontoid calcifications are common and should not preclude further investigations.

Computed tomography imaging characteristics help to differentiate pyogenic spondylitis from brucellar spondylitis

PURPOSE

Both pyogenic spondylitis (PS) and brucellar spondylitis (BS) can cause deformities and permanent neurologic deficits without prompt diagnosis and treatment. However, differential diagnosis is challenging. The aim of this study was to compare the computed tomography (CT) imaging features of PS with those of BS.

METHODS

Thirty-two patients with PS and 44 with BS were enrolled in the study. CT images were obtained in all cases. Data on bone destruction and formation, vertebral wall destruction, and osteosclerotic changes were collected and compared using the Chi-square test or t test. A P value < 0.01 was considered statistically significant. Positive predictive values (PPV) for detecting PS or BS were reported.

RESULTS

Involvement of the lumbar vertebrae and multiple spinal levels was more common in the BS group than in the PS group. Bone destruction was significantly greater in the PS group than in the BS group (30.8 vs 18.0%; t = 3.920, P = 0.000), with more extensive destruction of the vertebral body (35.8 vs 12.5%, χ² = 12.672, P = 0.002, PPV = 63.16%). In the BS group, there was more osteosclerosis around erosions (70.5 vs 43.3%, χ² = 11.59, P = 0.001, PPV = 67.74%) and fan-shaped osteosclerosis (27.3 vs 19.4%, χ² = 18.556, P = 0.006, PPV = 64.86%), more bone formation around the vertebra (77.2 vs 34.3%, χ² = 33.608, P = 0.000, PPV = 76.83%), more bone formation under the anterior longitudinal ligament (63.6 vs 19.4%, χ² = 30.133, P = 0.000, PPV = 76.09%), more longer anterior bone formation (3.55 vs 0.78 mm, t = 3.997, P = 0.000), and more anterior and closed-bone formation with local erosion (42.0 vs 9.0%, χ² = 74.243, P = 0.000, PPV = 74.36%).

CONCLUSIONS

CT images have unique advantages of revealing the morphology of erosions, osteosclerosis, and bone formation around the vertebra and help to differentiate PS from BS. These slides can be retrieved under Electronic Supplementary Material.

Diagnostic performance of 18F-FDG PET/CT in patients with spinal infection: a systematic review and a bivariate meta-analysis

PURPOSE

Diagnosis of spinal infection (SI) is challenging and usually requires multiple tests. We aimed to perform a systematic review and a bivariate meta-analysis on the diagnostic role of ¹⁸F-FDG PET/CT in patients with SI.

METHODS

A comprehensive literature search of studies published through February 2019 in PubMed/MEDLINE and Cochrane library databases was carried out. Studies investigating the diagnostic performance of ¹⁸F-FDG PET/CT in patients with SI were eligible for inclusion in the qualitative analysis. For the quantitative analysis, pooled sensitivity, specificity, positive and negative likelihood ratio (LR+ and LR-) and diagnostic odds ratio (DOR) of ¹⁸F-FDG PET/CT in patients with suspected SI were calculated on a per examination-based analysis. Pooled data were presented with 95% confidence intervals (95% CI).

RESULTS

Twenty-six articles (833 patients) using ¹⁸F-FDG PET/CT were eligible for the qualitative analysis. Twelve studies (396 patients) were selected for the meta-analysis. Overall, ¹⁸F-FDG PET/CT demonstrated a very good diagnostic performance in patients with SI and several studies underlined the value of ¹⁸F-FDG PET/CT in assessing the response to treatment. The bivariate meta-analysis on ¹⁸F-FDG PET/CT in patients with suspected SI provided the following results: sensitivity 94.8% (95% CI 88.9-97.6%) and specificity 91.4% (95% CI 78.2-96.9%). The pooled LR+, LR- and DOR were 4.7 (95% CI 2.9-7.7), 0.11 (95% CI 0.07-0.16) and 63.4 (95% CI 28.9-139), respectively. No significant heterogeneity or publication bias was found.

CONCLUSION

¹⁸F-FDG PET/CT demonstrated a very good diagnostic performance in patients with SI and can be used in patients in which MRI cannot be performed or is non-diagnostic or inconclusive. Several studies underlined the value of ¹⁸F-FDG PET/CT in assessing the response to treatment in patients with SI. Overall, larger multicentre and prospective studies and cost-effectiveness analyses are warranted.

Molecular Imaging of Infection: The First 50 Years

Despite significant advances in the understanding of microorganisms and an increased availability of antimicrobial therapy, infection remains a major cause of morbidity and mortality. The diagnosis can be challenging and imaging studies often are used for confirmation and localization. For nearly 50 years, molecular imaging agents have played an important role in the diagnosis of infection. Gallium-67 citrate was perhaps the first molecular imaging agent used for diagnosing and localizing infection. Poor imaging characteristics, along with a lack of specificity, and the long (usually 48-72 hours) interval between administration and imaging motivated investigators to search for alternatives. Currently the role of ⁶⁷Ga is limited to differentiating acute tubular necrosis from interstitial nephritis and as an alternative to ¹⁸F-FDG for indications, such as sarcoid, spondylodiscitis, and fever of unknown origin, when the latter is not available. The development, in the mid-1970s, of techniques for radiolabeling leukocytes that subsequently migrate to foci of infection was a significant advance and labeled leukocyte imaging still has a preeminent role in molecular imaging of infection. There are significant disadvantages to in-vitro labeled leukocyte imaging. Efforts devoted to developing in-vivo leukocyte labeling methods, however, met with only limited success. Over the past 20 years ¹⁸F-FDG has established itself as the molecular imaging agent of choice for fever of unknown origin, vasculitis, sarcoid, and spondylodiscitis. As useful as these agents are, their uptake is based on the host response to infection, not infection itself. Previous attempts at developing infection specific agents, including radiolabeled antibiotics, antibiotics, and vitamins like biotin were limited by poor results and/or limited availability and so investigators continue to focus on developing infection specific molecular imaging agents. Initial results with radiolabeled nucleoside analogs, sugars, and amino acids, and a renewed interest in radiolabeled antibiotics for both diagnosis and monitoring treatment are exciting and hold great promise for the future.

Erosive effects of a posterior mediastinal mass in a 18th to early 19th c. Spanish child mummy

During the 2011 restoration works in the central nave of the church of the Assumption of Our Lady, known as "The Piquete", in the village of Quinto (about 50 kms southwest of Zaragoza, Spain), the remains of 70 individuals were uncovered. Of these there were 32 mummified bodies, four of which have been investigated with CT scans. Here we report on the findings in one such individual, namely a child of between 7 and 8 years of age, whose sex is debatable but may well be female. The main pathological finding is the presence of pressure erosion and distortion of the upper thoracic spine, the cause of which is discussed with the conclusion that this may well represent a neurenteric duplication cyst. The possible consequences of such a lesion are considered.

Spondylodiscitis following endovascular abdominal aortic aneurysm repair: imaging perspectives from a single centre's experience

OBJECTIVE

Very few reports have previously described spondylodiscitis as a potential complication of endovascular aortic aneurysm repair (EVAR). We present to our knowledge the first case series of spondylodiscitis following EVAR based on our institution's experience over an 11-year period. Particular attention is paid to the key imaging features and challenges encountered when performing spinal imaging in this complex patient group.

MATERIALS AND METHODS

Of 1,847 patients who underwent EVAR at our institution between January 2006 and January 2017, a total of 9 patients were identified with imaging features of spondylodiscitis (0.5%). All cross-sectional studies before and after EVAR were assessed by a Consultant Musculoskeletal Radiologist and a Musculoskeletal Radiology Fellow to evaluate for features of spondylodiscitis.

RESULTS

All 9 patients had single-level spondylodiscitis involving lumbosacral levels adjacent to the aortic/iliac stent graft. Eight out of nine patients had an extensive anterior paravertebral phlegmon/abscess that was contiguous with the infected stent graft and native aneurysm sac ± anterior vertebral body erosion. Epidural disease was present in only 3 out of 9 patients and was a minor feature. MRI was non-diagnostic in 3 out of 9 patients owing to susceptibility artefact. ¹⁸F-FDG PET/CT accurately depicted the spinal level involved and adjacent paravertebral disease in patients with non-diagnostic MRI and was adopted as the follow-up modality in 3 out of 5 surviving patients.

CONCLUSION

Spondylodiscitis is a rare complication post-EVAR. Imaging features of disproportionate anterior paravertebral disease and anterior vertebral body bony involvement suggest direct spread of infection posteriorly to the adjacent vertebral column. Use of MRI versus ¹⁸F-FDG PET/CT as the optimal imaging modality should be directed by the type of stent graft deployed.