Spinal fusion-hardware construct: Basic concepts and imaging review

The interpretation of spinal images fixed with metallic hardware forms an increasing bulk of daily practice in a busy imaging department. Radiologists are required to be familiar with the instrumentation and operative options used in spinal fixation and fusion procedures, especially in his or her institute. This is critical in evaluating the position of implants and potential complications associated with the operative approaches and spinal fixation devices used. Thus, the radiologist can play an important role in patient care and outcome. This review outlines the advantages and disadvantages of commonly used imaging methods and reports on the best yield for each modality and how to overcome the problematic issues associated with the presence of metallic hardware during imaging. Baseline radiographs are essential as they are the baseline point for evaluation of future studies should patients develop symptoms suggesting possible complications. They may justify further imaging workup with computed tomography, magnetic resonance and/or nuclear medicine studies as the evaluation of a patient with a spinal implant involves a multi-modality approach. This review describes imaging features of potential complications associated with spinal fusion surgery as well as the instrumentation used. This basic knowledge aims to help radiologists approach everyday practice in clinical imaging.     

Imaging features of postoperative complications after spinal surgery and instrumentation

OBJECTIVE: The purpose of this article is to illustrate common postoperative complications and their imaging appearances after spinal surgery, including stabilization, fusion, and disk replacement with various techniques and devices. CONCLUSION: Radiography is the primary modality for routine follow-up, but MDCT has become the standard for optimized assessment of postoperative implants, and MRI plays a major role in the diagnosis of complications such as infection and soft-tissue lesions.     

Imaging in adult scoliosis: preoperative assessment and postoperative complications

Adult scoliosis rates range from 2 to 32%. Surgery for scoliosis is common. Accurate and surgically relevant information should be provided to the referring surgeon from pre- and postoperative imaging. There are various methods to correct scoliosis surgically with the end points correction of the curve and relief of symptoms. This is achieved through the placement of spinal instrumentation with a goal of osseous fusion across the instrumented levels. There are many potential postoperative complications. The initial and postoperative imaging, types of surgery, and hardware are reviewed along with the common early and late complications with relevant illustrations.     

Radiology of cardiac devices and their complications

This article familiarizes the reader with several different cardiac devices including pacemakers and implantable cardioverter defibrillators, intra-aortic balloon pumps, ventricular assist devices, valve replacements and repairs, shunt-occluding devices and passive constraint devices. Many cardiac devices are routinely encountered in clinical practice. Other devices are in the early stages of development, but circumstances suggest that they too will become commonly found. The radiologist must be familiar with these devices and their complications.Cardiac devices such as pacemakers have now been improving patient morbidity and mortality for decades. Radiology has played an integral role in device pre-procedural planning, placement and continued evaluation. This article aims to review cardiac devices that have been in use for a long time, including pacemakers, implantable cardioverter defibrillators (ICDs), the intra-aortic balloon pump (IABP) and valve repairs/replacements. Decades of use have provided ample data regarding their normal radiographic appearances and complications. In addition, contemporary advances have impacted our understanding of newer devices and their complications. Because of the increasing use of these devices, it is of utmost importance to be aware of their complications. The ventricular assist devices (VADs) have benefitted greatly from recent technological advances, and they continue to evolve. Furthermore, new devices such as percutaneous valve replacements and passive constraint devices continue to emerge. Radiologists interpreting thoracic imaging studies should become familiar with their appearances and potential complications.     

Magnetic resonance imaging near metal implants

The desire to apply magnetic resonance imaging (MRI) techniques in the vicinity of embedded metallic hardware is increasing. The soft-tissue contrast available with MR techniques is advantageous in diagnosing complications near an increasing variety of MR-safe metallic hardware. Near such hardware, the spatial encoding mechanisms utilized in conventional MRI methods are often severely compromised. Mitigating these encoding difficulties has been the focus of numerous research investigations over the past two decades. Such approaches include view-angle tilting, short echo-time projection reconstruction acquisitions, single-point imaging, prepolarized MRI, and postprocessing image correction. Various technical advances have also enabled the recent development of two alternative approaches that have shown promising clinical potential. Here, the physical principals and proposed solutions to the problem of MRI near embedded metal are discussed.     

Inferior Vena Cava Filter Strut Penetration into the Vertebral Column: A Case of 10-Year Clinical Follow Up

BackgroundThe rate of vena cava (IVC) filter placement has increased over the past decade, especially in the orthopaedic trauma patient population. With the increasing use of IVC filters, radiologists and referring clinicians must be familiar with potential complications.Clinical CaseThis case report presents an 18-year-old polytraumatized patient who had an IVC filter placed and required T8-L2 posterior spinal fusion. At 4.5 years of follow-up, a computed tomography (CT) scan for painful spinal hardware incidentally found that the IVC filter had migrated into the L3 vertebral body. The patient eventually underwent removal of her spinal hardware, but the IVC filter migration was managed conservatively with routine surveillance. At 10 years follow-up, the patient continued to remain asymptomatic despite of filter penetration into the vertebral body.ConclusionThis case demonstrates, long term follow-up for an asymptomatic patient with IVC migration and vertebral body penetration. This case may suggest that attempt at complex IR filter retrieval is not necessarily warranted in scenarios of strut penetration.     

Vascular complications in lumbar disk surgery: report of four cases

Vascular injuries in lumbar disk surgery, although rare, are serious complications which may be overlooked due to a broad range of clinical manifestations. It is important that surgeons and radiologists be aware of these potentially fatal complications and develop an appropriate symptom-based diagnostic paradigm. We reviewed 8099 consecutive cases of lumbar disk surgery, performed over a 14-year period at a single institution, for postoperative vascular complications. We identified four patients (0.05%) with lumbar disk surgery-related vascular complications: intraoperative lacerations of the abdominal aorta and median sacral artery, an arteriovenous fistula between the left common iliac artery and vein detected 19 days postdiskectomy, and a partially thrombosed aortic aneurysm with an arteriovenous fistula between the aneurysm and the inferior vena cava, diagnosed 11 months after surgery. The majority of cases in the literature of vascular injury in lumbar disk surgery were reported prior to 1965. Diagnostic approaches described in that period do not reflect the great range of diagnostic techniques available today. Angiography remains the gold standard for diagnosis and guidance as to surgical repair. However, a high index of suspicion based on clinical signs and/or the use of sonography or CT is important in the detection of these complications.     

Bariatric surgery: a review of normal postoperative anatomy and complications

The number of bariatric surgery procedures performed is increasing every year. Patients may be referred for radiological investigations to exclude complications not only in the early postoperative period but many months later. Radiologists who do not work in bariatric centres are therefore required to have an understanding of the complex normal anatomy and complications associated with bariatric surgery to interpret imaging studies correctly. The purpose of this article is to describe the surgical techniques and normal anatomy of the four bariatric operations performed today, review the most common problems encountered in this patient group, and to describe the imaging findings that allow the accurate diagnosis of complications. In particular, we focus on identification of the internal hernia, a grave complication of bariatric surgery often missed by radiologists.     

Plain radiograph assessment of spinal hardware

The frequency and variety of spinal instrumentation has increased tremendously over the past 100 years, and imaging plays an important role in evaluating the postoperative spine. Although assessment of spinal hardware often involves a multimodality approach, plain radiographs are the most commonly used modality, given accessibility, cost, relatively low radiation dose compared with computed tomography, and provision of positional information. An approach to assessment of plain radiographs of the postoperative spine is discussed, and examples of common postoperative complications are provided, including infection, hardware failure, incomplete fusion, and junctional failure.     

Pediatric hematopoietic stem cell transplantation and the role of imaging

The use of hematopoietic stem cell transplantation (HSCT) in the treatment of children afflicted with many potentially fatal malignant and nonmalignant diseases is well recognized. Although outcomes continue to improve and the utility of HSCT is increasing, HSCT remains a complicated process necessitating support from many medical disciplines, including radiology. Importantly, children who undergo HSCT are at risk for the development of specific complications that are linked to the timeline of transplantation, as well as to the relationship between the underlying diagnoses, severe immune deficiency, cytoreductive regimen, and graft-versus-host reactions. An understanding of the complex interplay of the immune status, therapeutic regimen, and disease allows increased diagnostic accuracy. Successful treatment of these high-risk children requires that radiologists who are involved with their care be familiar with broad concepts, as well as with specific problems that frequently occur following HSCT. In this article, the clinical aspects of pediatric HSCT are summarized, including common complications, and imaging features of these complications are described.     

Bone SPECT/CT in the postoperative spine: a focus on spinal fusion

Low back pain is a global problem affecting one in 10 people. The management of low back pain varies from conservative to more invasive methods with a spectacular increase in the number of patients undergoing spinal fusion surgery during the last decade. Conventional radiological and radionuclide studies are often used in the assessment of persistent or recurring pain after spinal surgery with several advantages and limitations related to each technique. This article reviews the key contribution of integrated bone SPECT/CT in evaluating patients with persistent or recurring pain after spinal surgery, focusing on spinal fusion. Current literature supports the use of bone SPECT/CT as an adjunct imaging modality and problem-solving tool in evaluating patients with suspicion of pseudarthrosis, adjacent segment degeneration, and hardware failure. The role of bone SPECT/CT in post-operative orthopaedic scenarios is evolving, and this review highlights the need for further research on the role of bone SPECT/CT in these patients.     

Value of polydirectional tomography in the assessment of the postoperative spine after anterior decompression and vertebral body autografting

With the growing number of orthopedic reconstructive spinal procedures, the use of bone grafting has steadily increased in the past decade. An understanding of the biology of bone grafting is essential for both the clinician and radiologist. Despite the advent of computed tomography and magnetic resonance imaging, conventional polydirectional tomography remains an important tool in the evaluation of vertebral body autografts. Trispiral or hypocycloidal tomography plays a valuable role in the assessment of bone graft fusion and possible complications, especially in the presence of metallic fixation devices. We present our imaging experience derived from 375 patients with cervical, thoracic, or lumbar anterior spinal fusion. True graft complications occurred in 27 patients (7%) and consisted of fracture (4%), malpositioning (3%), and infection (<1%).     

Complications from sinonasal surgery

Endoscopic sinonasal surgery is the main procedure in sinonasal pathology. Complications are rare but potentially severe given the close relationship between the nasal cavities and sinuses and the orbit, skull base and carotid arteries. The different types of surgeries along with the mechanisms of injury, presenting signs and symptoms, and imaging features of the different surgical complications will be reviewed. We will also review the anatomical variants increasing the surgical risk that radiologists should describe on preoperative imaging studies.     

Complications of esophageal surgery: role of imaging in diagnosis and treatments

Esophageal surgery is a common and integral component in the management of hiatal hernias, esophageal carcinoma, and esophageal perforation. Understanding the expected postsurgical imaging features of these common esophageal surgeries and postoperative complications is essential. Image-guided intervention can be used to aid the surgeon in the management of many post esophageal surgical complications. We discuss the imaging features of the postoperative esophagus and the use of imaging, including fluoroscopy and computed tomography, in the diagnosis of post esophageal surgical complications and treatment.     

Postoperatives Syndrom nach Wirbelsäuleneingriffen

Postoperative syndrome after spine surgery, i.e., symptoms or syndromes caused by complications or procedure-related consequences, is gaining more and more importance. Due to great improvements concerning imaging and operative techniques (microsurgery, instrumentation) the total number of spinal surgeries as well as their related complications are increasing. Procedure-related postoperative complications including neurological deficit syndromes can occur acutely or at a later date. Concerning imaging techniques for postoperative evaluation after spinal surgery there are several modalities available. Their indications depend on complex factors including initial pathology the surgery was performed for, kind of surgical technique (surgical approach, instrumentation), anatomy of the patient as well as the time between onset of symptoms and surgery. In cases of ambiguous findings, the combination of different imaging techniques can be instrumental.     

Skull base tumours Part II. Central skull base tumours and intrinsic tumours of the bony skull base

With the advances of cross-sectional imaging radiologists gained an increasing responsibility in the management of patients with skull base pathology. As this anatomic area is hidden to clinical exam, surgeons and radiation oncologists have to rely on imaging studies to plan the most adequate treatment. To fulfil these endeavour radiologists need to be knowledgeable about skull base anatomy, about the main treatment options available, their indications and contra-indications and needs to be aware of the wide gamut of pathologies seen in this anatomic region. This article will provide a radiologists' friendly approach to the central skull base and will review the most common central skull base tumours and tumours intrinsic to the bony skull base.     

Aesthetic surgery of the buttocks: imaging appearance

Familiarity with the imaging appearance and potential complications of buttocks aesthetic surgery is important for radiologists. In this review, we illustrate the spectrum of imaging features after buttocks implants, liposuction, fat injections and silicone injections. Complications such as fat necrosis, abscess, and silicone migration are also presented.     

With advances in medical imaging can the radiologist reliably diagnose Wilms' tumours?

AIM: To evaluate whether radiologists can accurately differentiate Wilms' tumours from other paediatric abdominal masses with renal involvement using modern imaging methods alone. METHODS: From February 1993 to June 1997, 23 patients presented to the Paediatric Oncology Service at The Royal Hospital for Sick Children, Edinburgh with an intra-abdominal mass which had renal involvement. Nine patients had Wilms' tumours, 12 had neuroblastomas, one patient had xanthogranulomatous pyelonephritis and there was a single case of a mesoblastic nephroma. In each case, two radiologists retrospectively reviewed the initial imaging examinations and independently reached a radiological diagnosis. RESULTS: The radiologists were concordant and reached the correct diagnosis in 20/23 cases (87%), unsure of the diagnosis in one case (4.3 %) and discordant in two cases (8.7 %). Radiologists should be aware that a mesoblastic nephroma can have identical imaging features to a Wilms' tumour. In most cases, ultrasound and a chest X-ray were sufficient to reach the correct diagnosis although computed tomography (CT) and magnetic resonance imaging were superior for demonstrating the relationship of the mass to the great vessels, retroperitoneum and spinal canal. Inferior vena cava invasion was strongly predictive of a Wilms' tumour. Displacement of the great vessels, extension of the mass across the mid-line, renal displacement and tumour calcification on CT were more suggestive of a neuroblastoma although these features were also seen in a significant number of patients with Wilms' tumours. Encasement of vessels by tumour, a paravertebral mass and spinal canal invasion were highly predictive of neuroblastoma. CONCLUSION: In this study, radiologists were accurate at diagnosing Wilms' tumours using modern imaging methods, however, care should be taken in children who are less than 1 year of age as a mesoblastic nephroma may have identical imaging characteristics.     

CT findings of rupture, impending rupture, and contained rupture of abdominal aortic aneurysms

OBJECTIVE: With the increasing use of cross-sectional imaging for a variety of medical and surgical conditions affecting the abdomen and pelvis, familiarity with the imaging features of aneurysm rupture--and the findings suspicious for impending or contained aneurysm rupture--is crucial for all radiologists. This pictorial essay will review the imaging findings of rupture of abdominal aortic aneurysms and of complicated aneurysms. CONCLUSION: Prompt detection of abdominal aortic aneurysm rupture or impending rupture is critical because emergent surgery may be required and patient survival may be at stake.     

Magnetic Resonance Imaging in Children with Scoliosis

For many years, orthopaedic surgeons and radiologists have used plain-film radiography for diagnosis, treatment decision-making, and postsurgical evaluation of scoliosis. Recently, the direct visualization of the spinal canal and spinal cord became possible with the development of magnetic resonance imaging (MRI), which over a short period of time has become an indicated procedure in children with juvenile-onset idiopathic scoliosis and congenital scoliosis. Children with idiopathic scoliosis associated with neurologic findings on physical examination, with pain or rapid progression of the spine curvature are also being evaluated with MRI, especially if surgery for stabilization of the spine is planned. The use of MRI as a screening modality for all children with scoliosis is still controversial and further studies are needed to evaluate if the examination adds or changes the treatment of these patients.