Medical Devices of the Head, Neck, and Spine

Hypoglossal nerve stimulator on extraoral radiography and cone beam computed tomography scan: Case report

BACKGROUND

The hypoglossal nerve stimulator (HNS) device has been employed in some patients with refractory or unsatisfactory outcomes to chronic obstructive sleep apnea management. The objective of this article is to increase recognition of the radiologic appearances of this device within the head and neck region, as seen on extraoral radiographic and cone beam computed tomography (CBCT) images.

CLINICAL PRESENTATION

A 55-year-old man, refractory to a multitude of apneic medical therapies, underwent a series of preorthognathic radiologic studies. Notably, an implanted HNS lead and ribbon electrodes appeared as hyperdense structures on the panoramic radiograph, lateral cephalogram, and CBCT scan.

CONCLUSION

This article provides various radiologic views of the primary components of an HNS. Clinicians should be able to recognize the presence of neurostimulator devices used for management of chronic sleep apnea within the radiologic field of view of examinations of the head and neck.

Incidental detection of bilateral cochlear implants on panoramic radiography: Case report associated with antecedent traumatic brain injury

Patients with chronic and severe hearing loss, refractory to nonsurgically-worn devices, may consider use of cochlear implants to regain auditory capability. Cochlear implants consist of surgically emplaced and externally worn components. There are few published examples of the radiographic presentation of these devices appearing in the special needs-based dental literature. This article features a case report and panoramic radiographic examination involving a 67-year-old patient who received bilateral cochlear implants after experiencing a traumatic brain injury and onset loss of hearing. A brief review of strategies for communicating with individuals with severe hearing impairment has also been provided.

Wearable neck assistive device strain evaluation study on surface neck muscles for head/neck movements

BACKGROUND

This article examines a dynamic wearable assistive device for individuals suffering from pain in the neck. As a part of the clinical treatment, static braces/cervical collars are suggested, however, these collars aid the person in maintaining the upright position of the head but restrict the head motion to a single configuration. To address this problem, a dynamic wearable assistive cervical collar is fabricated based on human anatomical head/neck data.

OBJECTIVE

The objective of this study is to observe the strain acting on the neck surface muscles for bending and compression neck movements with and without the neck brace using a strain sensor.

METHODS

To evaluate the perform of this device, experimental trials were conducted on test subjects to find out the angular tilt of the head with the device worn using the cervical range of motion (CROM) device. In addition, a neck surface muscle strain study is also conducted using strain sensors to investigate the strain produced while using the wearable assistive device. The strain on the neck surface muscle is measured using NI-9236 strain DAQ (data acquisition system). In this experimental study, a group of aged individuals with minor neck pain were recruited to study the head/neck movements.

RESULTS

It was found that by using the proposed assistive device, test subjects were able to mimic 65% of human head/neck movements like flexion, extension, lateral bending, and rotation, and the strain generated from the neck surface muscle was minimal.

CONCLUSION

The results show that using the designed assistive device reduced the strain on neck surface muscle, and strain obtained is within the range of 40 × 10-6 to 80 × 10-6, and may aid in recovery of the individuals suffering with neck pain.

Back to Fundamentals: Radiographic Evaluation of Thoracic Lines and Tubes in Children

OBJECTIVE. The purpose of this article is to provide an up-to-date review of the radiographic appearance of the most commonly used thoracic lines and tubes in pediatric patients in daily clinical practice. CONCLUSION. Thoracic support lines and tubes are frequently used in children receiving hospital care. Evaluation of these devices is a fundamental skill in radiology. Many different devices are currently used, and new devices are regularly introduced. It is essential for radiologists to maintain a clear understanding of all devices currently in use.

Monte Carlo simulation and film dosimetry for electron therapy in vicinity of a titanium mesh

Titanium (Ti) mesh plates are used as a bone replacement in brain tumor surgeries. In the case of radiotherapy, these plates might interfere with the beam path. The purpose of this study is to evaluate the effect of titanium mesh on the dose distribution of electron fields. Simulations were performed using Monte Carlo BEAMnrc and DOSXYZnrc codes for 6 and 10 MeV electron beams. In Monte Carlo simulation, the shape of the titanium mesh was simulated. The simulated titanium mesh was considered as the one which is used in head and neck surgery with a thickness of 0.055 cm. First, by simulation, the percentage depth dose was obtained while the titanium mesh was present, and these values were then compared with the depth dose of homogeneous phantom with no titanium mesh. In the experimental measurements, the values of depth dose with titanium mesh and without titanium mesh in various depths were measured. The experiments were performed using a RW3 phantom with GAFCHROMIC EBT2 film. The results of experimental measurements were compared with values of depth dose obtained by simulation. In Monte Carlo simulation, as well as experimental measurements, for the voxels immediately beyond the titanium mesh, the change of the dose were evaluated. For this purpose the ratio of the dose for the case with titanium to the case without titanium was calculated as a function of titanium depth. For the voxels before the titanium mesh there was always an increase of the dose up to 13% with respect to the same voxel with no titanium mesh. This is because of the increased back scattering effect of the titanium mesh. The results also showed that for the voxel right beyond the titanium mesh, there is an increased or decreased dose to soft tissues, depending on the depth of the titanium mesh. For the regions before the depth of maximum dose, there is an increase of the dose up to 10% compared to the dose of the same depth in homogeneous phantom. Beyond the depth of maximum dose, there was a 16% decrease in dose. For both 6 and 10 MeV, before the titanium mesh, there was always an increase in dose. If titanium mesh is placed in buildup region, it causes an increase of the dose and could lead to overdose of the adjacent tissue, whereas if titanium mesh is placed beyond the buildup region, it would lead to a decrease in dose compared to the homogenous tissue.

Assessment of telemetry and fluidic control system used in the Medstream programmable infusion system: an in vivo and in vitro study

The MedStream Programmable Infusion Pump, an intrathecal pump indicated for the treatment of chronic intractable pain and severe spasticity (CE-mark) or severe spasticity (US), has a highly accurate medication delivery (within 10% of the programmed flow rate) and is certified for use in 3-Tesla magnetic resonance imaging systems (conditional). Performance of the telemetric link between external control-unit and implanted pump was assessed in sheep (in vivo) up to 26 weeks, resulting in 1040 communication sessions. The telemetric communication envelope (communication distance and maximum antenna tilt angles) and communication duration were characterized in an in vitro test. Capacitance measurements of the piezoelectric actuator of the valve, valve flow rates, and leak rates were measured in an in vitro cyclic accelerated aging test to assess reliability of the valve over 6,200 k cycles. The pump was well tolerated in vivo; all communication sessions between control-unit and pump were successful (P = 6.889 × 10(-14)). Mean communication distance between pump and control-unit was 3.8 cm, with the maximum antenna tilt angles being 40° (θy) and 50° (θx) for all test cases; the maximum communication duration was 5.5 s. Capacitance measurements, flow rates, and leak rates were within ±10 % range up to 6,200 k cycles corresponding to approximately 10 times the valve cycles over the specified service life of the pump (8 years), except for one flow-rate value, which can be explained by the measurement setup. These results demonstrate the reliability of the telemetry link and piezoelectric valve system of the MedStream Programmable Infusion Pump.

Evaluation of operator radioprotection using a new injection device during vertebroplasty

This study aimed to evaluate the protection granted by a simple device (X'TENS(®), Thiebaud, France) and to provide operators with information on the performance of this new device, which has not yet been assessed. Our assumption is that this device efficiently reduces the radiation dose to the operator. In a prospective clinical study, the radiation dose the operator's hand receives has been assessed using a specific sensor (UNFOR Instrument). Each patient included in the study was to receive at least two injections of cement during the procedure. Exposure was measured with and without the range extender. The data collected were then processed using a Wilcoxon matched pairs test. During 14 interventions, 20 vertebrae were treated with both procedures. Eleven women and three men were included. Seven patients underwent vertebroplasty for metastatic lesions and seven for osteoporotic lesions, bone fractures or vertebral compressions. The average injection time was 1.35 minutes with the device and 1.20 without (p=0.75). The dose to the hand per ml injected was 111.37 vs. 166.91 (p<0.05). Theoretically, the protection granted by the range extender depends on the length of the device. Our results are consistent with the inverse-square law. However, the variations in our results indicate that a proper and rigorous use is mandatory for the device to be effective. Given that radioprotection during fluoroscopy procedures is a frequently raised issue, the need for information for a safer practice increases likewise.

Dose distribution near thin titanium plate for skull fixation irradiated by a 4-MV photon beam

To investigate the effects of scattered radiation when a thin titanium plate (thickness, 0.05 cm) used for skull fixation in cerebral nerve surgery is irradiated by a 4-MV photon beam. We investigated the dose distribution of radiation inside a phantom that simulates a human head fitted with a thin titanium plate used for post-surgery skull fixation and compared the distribution data measured using detectors, obtained by Monte Carlo (MC) simulations, and calculated using a radiation treatment planning system (TPS). Simulations were shown to accurately represent measured values. The effects of scattered radiation produced by high-Z materials such as titanium are not sufficiently considered currently in TPS dose calculations. Our comparisons show that the dose distribution is affected by scattered radiation around a thin high-Z material. The depth dose is measured and calculated along the central beam axis inside a water phantom with thin titanium plates at various depths. The maximum relative differences between simulation and TPS results on the entrance and exit sides of the plate were 23.1% and – 12.7%, respectively. However, the depth doses do not change in regions deeper than the plate in water. Although titanium is a high-Z material, if the titanium plate used for skull fixation in cerebral nerve surgery is thin, there is a slight change in the dose distribution in regions away from the plate. In addition, we investigated the effects of variation of photon energies, sizes of radiation field and thickness of the plate. When the target to be irradiated is far from the thin titanium plate, the dose differs little from what it would be in the absence of a plate, though the dose escalation existed in front of the metal plate.

Lumbar spine fusion and stabilization: hardware, techniques, and imaging appearances

Stabilization and fusion of the lumbar spine may be performed by using various anterior and posterior surgical techniques and a wide range of devices, including screws, spinal wires, artificial ligaments, vertebral cages, and artificial disks. Because spinal procedures are increasingly common, such devices are seen more and more often in everyday radiologic practice. For evaluation of the postoperative spine, radiography is the modality most commonly used. Computed tomography and magnetic resonance (MR) imaging may be useful alternatives, but MR imaging of the postoperative spine is vulnerable to metal-induced artifacts. For an accurate postoperative assessment of spinal instrumentation and of any complications, it is important that radiologists be familiar with the normal imaging appearances of the lumbar spine after stabilization, fusion, and disk replacement with various techniques and devices.

The utility of the plain radiograph "shunt series" in the evaluation of suspected ventriculoperitoneal shunt failure in pediatric patients

BACKGROUND

To our knowledge, the sensitivity of plain radiography, known as the shunt series, in diagnosing an etiology of ventriculoperitoneal (VP) shunt malfunction in children has not been previously investigated.

OBJECTIVE

To determine the accuracy of plain radiography in diagnosing VP shunt failure in children in whom shunt malfunction is clinically suspected.

MATERIALS AND METHODS

We retrospectively reviewed the charts of 238 children who had undergone plain radiographic examination for evaluation of clinically suspected VP shunt failure over a 5-year period. The results were compared with those of CT, MRI, and nuclear cisternography.

RESULTS

Just 6.72% of patients demonstrated plain radiographic signs of shunt failure. Of patients with normal plain radiographs, 43% demonstrated shunt abnormalities on CT, MRI or cisternography. Statistical analysis indicated that no more than 10.46% (P < 0.05) of plain radiographs showed signs of failure and that the sensitivity of plain radiography for the detection of VP shunt failure is no higher than 31%. Furthermore, there was poor agreement between the results of plain radiography and those of CT, MRI and cisternography.

CONCLUSION

Children with clinically suspected VP shunt failure should proceed directly to cross-sectional or nuclear imaging, as plain radiographic examinations have low sensitivity and significant false-negative rates for detecting shunt abnormalities in all-comers. Use of the shunt series should be limited to patients who specifically have suspected mechanical causes of shunt failure.

Yield and utility of radiographic “shunt series” in the evaluation of ventriculo-peritoneal shunt malfunction in adult emergency patients

We examined the yield and utility of shunt series (SS) performed for suspected shunt malfunction and whether an abnormal SS lead to shunt revision when head computed tomography (CT) was normal or unchanged. We reviewed medical records for all adult emergency patients over a 34-month period with suspected shunt malfunction imaged with both SS and head CT to determine whether a shunt revision was performed contemporaneous with imaging. Nine (3.4%) abnormal SS were identified among 263 studies performed. Among the 192 cases in which CT was normal or unchanged, two patients with abnormal SS underwent contemporaneous shunt revision. Yield of SS is very low, and in the presence of a normal or unchanged head CT, SS provides the imaging basis for contemporaneous shunt revision in 1% (2/192) of cases.

Platform technologies to support brain-computer interfaces

There is a lack of adequate and cost-effective treatment options for many neurodegenerative diseases. The number of affected patients is in the millions, and this number will only increase as the population ages. The developing areas of neuromimetics and stimulative implants provide hope for treatment, as evidenced by the currently available, but limited, implants. New technologies are emerging that are leading to the development of highly intelligent, implantable sensors, activators, and mobile robots that will provide in vivo diagnosis, therapeutic interventions, and functional replacement. Two key platform technologies that are required to facilitate the development of these neuromimetic and stimulative implants are data communication channels and the devices' power supplies. In the research reported in this paper, investigators have examined the use of novel concepts that address these two needs. These concepts are based on ionic volume conduction (VC) to provide a natural communication channel to support the functioning of these devices, and on biofuel cells to provide a continuously rechargeable power supply that obtains electrons from the natural metabolic pathways. The fundamental principles of the VC communication channels, including novel antenna design, are demonstrated. These principles include the basic mechanisms, device sensitivity, bidirectionality of communication, and signal recovery. The demonstrations are conducted using mathematical and finite element analysis, physical experiments, and animal experiments. The fundamental concepts of the biofuel cells are presented, and three versions of the cells that have been studied are discussed, including bacteria-based cells and two white cell-based experiments. In this paper the authors summarize the proof or principal experiments for both a biomimetic data channel communication method and a biofuel cell approach, which promise to provide innovative platform technologies to support complex devices that will be ready for implantation in the human nervous system in the next decade.

Medical devices of the chest

Chest devices are encountered on a daily basis by almost all radiologists. A multitude of extrathoracic materials, from intravenous catheters to oxygen tubing and electrocardiographic leads, frequently overlie the chest, neck, and abdomen. Chest tubes, central venous catheters, endotracheal tubes, and feeding tubes are very common. Cardiac surgery involves the use of many sophisticated devices and procedures, ranging from valve replacement to repair of complex congenital anomalies. Coronary artery bypass surgery is no longer considered unusual, and in many large medical centers, ventricular assist devices and total artificial hearts are frequently encountered. Breast implants are visible at standard chest radiography, and many ancillary devices not intended for treatment of cardiac or thoracic diseases are visible on chest radiographs. New devices are constantly being introduced, but most of them are variations on a previous theme. Knowing the specific name of a device is not important. It is important to recognize the presence of a device and to have an understanding of its function, as well as to recognize the complications associated with its use.

Part 2: Devices of the Head, Neck, Spine, Chest, and Abdomen

This gallery of medical devices illustrates a multitude of common devices in the head, neck, spine, chest, and abdomen that are found in daily radiologic practice (orthopedic devices for the extremities and pelvis were illustrated in Part 1). All these medical devices have been more thoroughly discussed in the previous articles in this medical devices series and in other detailed references. The present article is a comprehensive overview of these devices and provides a quick reference for identifying an unfamiliar device. It is intended to allow the reader to identify a device generically and to understand its purpose. It is important to recognize the presence of a device, understand its purpose and proper function, and recognize the complications associated with its use. Knowing the specific or proper brand name of every device is not important and frequently not possible. New devices are constantly being introduced, although most of them are variations of a previous device. Sometimes, so many devices are used in a patient's treatment that they obscure important anatomy and pathologic conditions (Fig 1). Herein, we present an overview of the many medical devices frequently used in the head, neck, and spine, including a halo device, aneurysm clips, spinal fusion devices, deep brain electrodes, sacral nerve stimulator, and vertebroplasty (Figs 2-9). We also illustrate numerous chest medical devices that are seen daily by almost all radiologists. These devices include a multitude of extrathoracic and intrathoracic apparatus, ranging from intravenous catheters to oxygen tubing and electrocardiographic leads, central venous catheters, chest tubes, endotracheal and feeding tubes, cardiac valves, coronary artery bypass stents, pacemakers, internal cardiac defibrillators, ventricular assist devices, and total artificial hearts (the latter two devices are frequently encountered in many large medical centers) (Figs 10-26). We also present medical devices of the abdomen and pelvis, which can be grouped into four major categories: intestinal tubes, genitourinary apparatus, postoperative apparatus, and vascular devices (Figs 27-47). For a detailed discussion of a particular device, the reader should refer to the appropriate references cited.