The diagnostic accuracy of imaging modalities to detect pseudarthrosis after spinal fusion-a systematic review and meta-analysis of the literature.

OBJECTIVE: The aim of the study was to determine the diagnostic accuracy of imaging modalities to detect pseudarthrosis after thoracolumbar spinal fusion, with surgical exploration as reference standard. MATERIALS AND METHODS: A systematic literature search for original studies was performed on the diagnostic accuracy of imaging as index test compared to surgical exploration as reference standard to diagnose pseudarthrosis after thoracolumbar spinal fusion. Diagnostic accuracy values were extracted and methodologic quality of studies was evaluated by the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool. Per modality, clinically comparable studies were included in subgroup meta-analysis and weighted odds ratios (ORs) were calculated using the random effects model. RESULTS: Fifteen studies were included. Risk of bias was classified as high/unclear in 58% of the studies. Concerns of applicability was classified as high/unclear in 40% of the studies. Four scintigraphy studies including 93 patients in total were pooled to OR = 2.91 (95% confidence interval [CI]: 0.93-9.13). Five studies on plain radiography with 398 patients in total were pooled into OR = 7.07 (95% CI: 2.97-16.86). Two studies evaluating flexion-extension radiography of 75 patients in total were pooled into OR = 4.00 (95% CI: 0.15-105.96). Two studies of 68 patients in total were pooled for CT and yielded OR = 17.02 (95% CI: 6.42-45.10). A single study reporting on polytomography, OR = 10.15 (95% CI 5.49-18.78), was also considered to be an accurate study. CONCLUSIONS: With a pooled OR of 17.02, CT can be considered the most accurate imaging modality for the detection of pseudarthrosis after thoracolumbar spinal fusion from this review.

Three-Dimensional Breast Radiotherapy and the Elective Radiation Dose at the Sentinel Lymph Node Site in Breast Cancer.

BACKGROUND: Several trials are presently randomizing clinically node-negative breast cancer patients treated with breast-conserving therapy (BCT) to sentinel lymph node biopsy (SLNB) or watchful waiting. We aimed to investigate the elective radiation dose at the sentinel lymph node (SLN) site while evaluating two techniques for SLN localization, in breast cancer patients treated with lumpectomy and three-dimensional (3D) whole-breast radiotherapy. METHODS: The SLN site of consecutive Tis-2N0 breast cancer patients undergoing lumpectomy and forward intensity-modulated whole-breast radiotherapy was determined by the location of the hotspot on preoperative single-photon emission computed tomography (SPECT)/computed tomography (CT) and by a surgical clip placed at the removed SLN(s) during SLNB. The radiation dose at the SLN site was subsequently determined on the postoperative radiotherapy planning CT. An elective radiation dose to the SLN site was defined as at least 95 % of the breast dose. RESULTS: Of the 42 included patients, the mean percentage of the breast dose on the SLN site was 90 % (standard deviation 26, range 7-132, median 99), with a non-significant difference between the two techniques (surgical clip or SPECT/CT) (p = 0.608). In 32/42 patients (76 %) the SLN site received an elective radiation dose. CONCLUSIONS: A surgical clip placed at the removed SLN(s) during SLNB proved to be an adequate method of determining the radiation dose at the SLN site when compared with using SPECT/CT. With the use of 3D radiotherapy, the site of the SLN is treated with an elective radiation dose in the majority of patients who are treated with BCT.

(18)F-FDG microPET imaging differentiates between septic and aseptic wound healing after orthopedic implant placement: a longitudinal study of an implant osteomyelitis in the rabbit tibia.

BACKGROUND AND PURPOSE: (18)F-FDG PET is a widely used tool for molecular imaging of oncological, cardiovascular, and neurological disorders. We evaluated (18)F-FDG microPET as an implant osteomyelitis imaging tool using a Staphylococcus aureus-induced peroperative implant infection in rabbits. METHODS: Intramedullary titanium nails were implanted in contaminated and uncontaminated (control) proximal right tibiae of rabbits. Tibiae were quantitatively assessed with microPET for (18)F-FDG uptake before and sequentially at 1, 3, and 6 weeks after surgery. Tracer uptake was assessed in soft tissue and bone in both treatment groups with an additional comparison between the operated and unoperated limb. MicroPET analysis was combined with radiographic assessment and complementary histology of the tibiae. RESULTS: At the first postoperative week, the (18)F-FDG uptake in the contaminated implant group was significantly higher than the preoperative measurement, without a significant difference between the contaminated and uncontaminated tibiae. From the third postoperative week onward, (18)F-FDG uptake allowed discrimination between osteomyelitis and postoperative aseptic bone healing, as well as quantification of the infection at distinct locations around the implant. INTERPRETATION: (18)F-FDG-based microPET imaging allows differentiation between deep infection and undisturbed wound healing after implantation of a titanium intramedullary nail in this rabbit model. Furthermore, our results indicate that (18)F-FDG PET may provide a tool in human clinical diagnostics and for the evaluation of antimicrobial strategies in animal models of orthopedic implant infection.

The Use of 18F-Fluoride Positron Emission Tomography/Computed Tomography Scanning to Identify Sources of Pain after Posterior Lumbar Interbody Fusion-An Analysis in Patients with and without Symptoms.

BACKGROUND: Identifying the cause of recurrent or persisting pain after posterior lumbar interbody fusion (PLIF) is essential for establishing optimal treatment. In this study, we evaluate patients after PLIF surgery by 18F-fluoride PET/CT scans and patient-reported outcome measures (PROMs). METHODS: A total of 36 PLIF patients were included. Sixty minutes after intravenous injection of 18F-fluoride, PET/CT scanning was performed. Bone graft ingrowth, subsidence, screw loosening and damage of facet joints were scored by quantifying the level of bone metabolism of the vertebral endplates in the disc spaces, around screws and around the facet joints on the PET scans. RESULTS: In contrast to asymptomatic patients, symptomatic patients showed abnormal PET values around pedicle screws and/or facet joints and at the lower endplates of the disc spaces, identifying a possible source of pain. On CT, no significant differences between these two groups were found. CONCLUSION: The PET/CT findings appeared to correlate better with symptoms on PROMs compared to CT findings alone. When interpreting 18F-fluoride PET/CT findings after PLIF surgery, one should realize bone metabolism in the disc spaces of the operated segments and around pedicle screws or facet joint changes during follow-up, reflecting natural recovery.

Synthesis and characterization of a new vertebroplasty cement based on gold-containing PMMA microspheres.

There are a number of drawbacks to incorporating large concentrations of barium sulfate (BaSO4) as the radiopacifier in PMMA-based bone cements for percutaneous vertebroplasty. These include adverse effects on injectability, viscosity profile, setting time, mechanical properties of the cement and bone resorption. We have synthesized a novel cement that is designed to address some of these drawbacks. Its powder includes PMMA microspheres in which gold particles are embedded and its monomer is the same as that used in commercial cements for vertebroplasty. In comparison to one such commercial cement brand, VertaPlex™, the new cement has longer doughing time, longer injection time, higher compressive strength, higher compressive modulus, and is superior in terms of cytotoxicity. For augmentation of fractured fresh-frozen cadaveric vertebral bodies (T6-L5) using simulated vertebroplasty, results for compressive strength and compressive stiffness of the construct and the percentage of the volume of the vertebral body filled by the cement were comparable for the two cements although the radiopacity of the new cement was significantly lower than that for VertaPlex™. The present results indicate that the new cement warrants further study.

The longitudinal assessment of osteomyelitis development by molecular imaging in a rabbit model.

INTRODUCTION: Osteomyelitis is a severe orthopaedic complication which is difficult to diagnose and treat. Previous experimental studies mainly focussed on evaluating osteomyelitis in the presence of an implant or used a sclerosing agent to promote infection onset. In contrast, we focused on the longitudinal assessment of a nonimplant related osteomyelitis. METHODS: An intramedullary tibial infection with S. aureus was established in NZW rabbits. Clinical and haematological infection status was evaluated weekly, combined with X-ray radiographs, biweekly injections of calcium binding fluorophores, and postmortem micro-CT. The development of the infection was assessed by micro-PET at consecutive time points using 18F-FDG as an infection tracer. RESULTS: The intramedullary contamination of the rabbit tibia resulted in an osteomyelitis. Haematological parameters confirmed infection in mainly the first postoperative weeks (CRP at the first 5 postoperative weeks, leucocyte differentiation at the second and sixth postoperative weeks, and ESR on the second postoperative week only), while micro-PET was able to detect the infection from the first post-operative week onward until the end of the study. CONCLUSIONS: This study shows that osteomyelitis in the rabbit can be induced without use of an implant or sclerosing agent. The sequential follow-up indicates that the diagnostic value of each infection parameter is time point dependant. Furthermore, from all parameters used, the diagnostic value of 18F-FDG micro-PET is the most versatile to assess the presence of an orthopaedic infection in this model.

Screening for brain metastases in patients with stage III non-small cell lung cancer: Is there additive value of magnetic resonance imaging above a contrast-enhanced computed tomography of the brain?

INTRODUCTION: Stage III NSCLC patients are candidates for treatment with curative intent. Current guidelines advise post contrast magnetic resonance imaging (MRI) or contrast enhanced computed tomography (CE-CT) of the brain in these patients to exclude brain metastases (BM). In previous small studies MRI was reported to be superior to CE-CT. However, CT and MR technology have evolved and 18F-deoxyglucose-positron-emission-tomography (18FDG-PET) has been implemented in staging of NSCLC. If CE-CT, performed together with 18FDG-PET-CT shows the same yield of BM detection as an additionally performed MRI, substantial gain in time and resources is expected. METHODS: All NSCLC patients who underwent a staging 18FDG-PET-CT between January 2008 and September 2011 were reviewed. Neurological asymptomatic patients with stage III NSCLC who were eligible for treatment with curative intent were selected, without taking into account the results of brain MRI. CT was compared to MRI to investigate whether additional BM were detected on MRI. Development of BM within a year after negative MRI was recorded. RESULTS: 97/429 NSCLC patients who underwent a PET-CT had stage III disease. Three otherwise stage III patients already had occult BM on CE-CT. 77/97 (79%) patients underwent MRI, 45/77 (58%) CE-CT and 32/77 (42%) LD-CT. In none of the CE-CT, but in 5/32 (16%) LD-CT patients BM were detected on MRI. 9/72 patients (13%) without BM on MRI at diagnosis developed BM within a year. CONCLUSIONS: This retrospective study suggests that there is no additive value of MRI to 18FDG-PET-CT with CE-CT in screening for BM in neurological asymptomatic patients with stage III NSCLC.