The Importance of Body Part Labeling to Enable Enterprise Imaging: A HIMSS-SIIM Enterprise Imaging Community Collaborative White Paper.

In order for enterprise imaging to be successful across a multitude of specialties, systems, and sites, standards are essential to categorize and classify imaging data. The HIMSS-SIIM Enterprise Imaging Community believes that the Digital Imaging Communications in Medicine (DICOM) Anatomic Region Sequence, or its equivalent in other data standards, is a vital data element for this role, when populated with standard coded values. We believe that labeling images with standard Anatomic Region Sequence codes will enhance the user's ability to consume data, facilitate interoperability, and allow greater control of privacy. Image consumption-when a user views a patient's images, he or she often wants to see relevant comparison images of the same lesion or anatomic region for the same patient automatically presented. Relevant comparison images may have been acquired from a variety of modalities and specialties. The Anatomic Region Sequence data element provides a basis to allow for efficient comparison in both instances. Interoperability-as patients move between health care systems, it is important to minimize friction for data transfer. Health care providers and facilities need to be able to consume and review the increasingly large and complex volume of data efficiently. The use of Anatomic Region Sequence, or its equivalent, populated with standard values enables seamless interoperability of imaging data regardless of whether images are used within a site or across different sites and systems. Privacy-as more visible light photographs are integrated into electronic systems, it becomes apparent that some images may need to be sequestered. Although additional work is needed to protect sensitive images, standard coded values in Anatomic Region Sequence support the identification of potentially sensitive images, enable facilities to create access control policies, and can be used as an interim surrogate for more sophisticated rule-based or attribute-based access control mechanisms. To satisfy such use cases, the HIMSS-SIIM Enterprise Imaging Community encourages the use of a pre-existing body part ontology. Through this white paper, we will identify potential challenges in employing this standard and provide potential solutions for these challenges.

CT of the hip prosthesis: appearance of components, fixation, and complications.

Multidetector computed tomography (CT) is an excellent way to supplement the radiographic evaluation of problematic hip prostheses. Multidetector CT is well suited for assessing periprosthetic bone, determining precise acetabular cup position, and evaluating periprosthetic fluid collections or ossified masses. Metal implants pose a number of challenges in the performance and interpretation of CT examinations. However, metal artifacts can be minimized by decreasing the detector collimation and pitch, increasing the kilovolt peak and milliampere-seconds, and using appropriate reconstruction algorithms and section thickness. Image interpretation requires a basic understanding of hip reconstruction and hip implants, as well as use of a systematic method of analysis that incorporates prior radiographic findings and CT findings. Radiologists must be familiar with the normal and abnormal CT appearances of hip prostheses and be able to recognize common complications on CT scans.

Feasibility of mapping T2 relaxation time in the pediatric metacarpal head with a 3-T MRI system.

OBJECTIVE: T2 relaxation time is sensitive in detecting early cartilage damage. There are few reports of T2 mapping for smaller joints because of technical challenges. The purpose of this study is to evaluate the feasibility of T2 mapping of the metacarpal head cartilage in children. CONCLUSION: T2 mapping of the metacarpal head cartilage is feasible in children on a 3-T scanner with commercially available coils. An increase in the T2 values near the osteochondral junction likely reflects the secondary physis.

Managing postoperative artifacts on computed tomography and magnetic resonance imaging.

Orthopedic hardware should not be considered a contraindication to computed tomography (CT) or magnetic resonance (MR) imaging. The hardware alloy, the geometry of the hardware, and the orientation of the hardware all affect the magnitude of image artifacts. For commonly encountered alloys, the severity of image artifacts is similar for CT and MR. Cobalt chrome or stainless steel hardware produces the most artifacts; titanium hardware produces the least. In general, image artifacts are most severe adjacent to the hardware. CT image artifacts are related to incomplete X-ray projection data resulting in streaks. These can be mitigated by increasing scan technique and using a smoother reconstruction filter. Hardware with a rectangular cross-sectional shape such as a fixation plate will cause more artifacts than a radially symmetrical device such as an intramedullary nail. Image artifacts at MR are caused by the hardware magnetic susceptibility and the induction of eddy currents within the metal. A turbo spin-echo sequence yields the best results. The use of larger image matrices, thinner slices, and a wide receiver bandwidth are recommended parameter adjustments when imaging patients with hardware. This article discusses how hardware-related artifacts can be minimized by altering scan technique and image reconstruction.

Current concepts and advances: computerized tomography in sports medicine.

Computed tomography (CT) is a widely used imaging technique. With the introduction of multidetector row technology, CT has been further refined. Although the focus of this transformation has been body and cardiac imaging, orthopedic imaging has benefited greatly. Specifically, the improvements in CT have made it possible to obtain submillimeter-thick slices that enable the creation of high-resolution multiplanar reformations from a single scan. These images usually are indistinguishable from direct plane acquisitions and provide unparalleled detail. Additionally, the factors responsible for causing CT image artifacts when hardware is present are much better understood and the improvements in CT technique and technology can be exploited to provide better images of patients with orthopedic hardware. The detailed multiplanar visualization of joints facilitates CT arthrography that has undergone a renaissance. CT arthrography is useful in the very large athlete or patient, the claustrophobic, and for those patients who fail a conventional magnetic resonance examination or magnetic resonance arthrogram.

Total hip arthroplasty in patients with bone deficiency of the acetabulum.

Total hip replacement (THR) requires revision in only a minority of cases (approximately 17% of prosthetic hips fail), but when THR failures occur there may be significant acetabular bone deficiency. There is a variety of surgical hardware and strategies available to address this problem. The causes of primary THR revision include aseptic loosening or particle disease, infection, recurrent dislocation, implant failure, periprosthetic fracture, and leg length discrepancy. Almost all patients who need THR revision undergo a standard radiographic evaluation of the pelvis and hip. In general, CT is an excellent tool for evaluating loosening of the prosthesis caused by either mechanical reasons or infection, and MR imaging is best suited for evaluating the soft tissues surrounding the prosthesis. Nuclear medicine studies are performed when results of CT and MR imaging are inconclusive. When patients are evaluated for revision THR, radiologists must check for acetabular cup loosening, the amount and type of bone stock loss, the amount of component migration, and the presence or absence of liner wear. Before revision hardware is placed, bone stock loss must be repaired, either by using bone grafting or by placing accessory acetabular hardware such as cups, rings, or cages. The long-term success of revision acetabular surgery varies; there is acetabular cup presence at 5 years after surgery in 60%-94% of cases. Complications include postoperative infections, repeat liner wear, bone graft failure, periprosthetic or prosthetic fractures, dislocation, vascular injury, and nerve injury.

The role of pelvic magnetic resonance in evaluating nonhip sources of infection in children with acute nontraumatic hip pain.

We retrospectively identified all children with acute hip pain who underwent pelvic magnetic resonance (MR). Children with septic hip or history of trauma were excluded; the remaining children with signs of infection (fever, >38 degrees C; leukocytosis, >12 x 10(9)/L; or elevated erythrocyte sedimentation rate [ESR], >30 mm/h) comprised the study group. Thirty-three children (9 girls; age, 0.8-15.8 years) were identified. On MR examination, 18 (55%) of 33 children had hip joint effusion, whereas 19 (58%) of 33 children had other abnormalities, including pyomyositis (n=15), osteomyelitis (n=12), and sacroiliitis (n=3). Staphylococcus aureus was cultured from 13 (68%) of these 19 children. Compared with MR, sensitivity for bone and soft tissue abnormalities was 30% for pelvic radiography (n=26) and 71% for bone scintigraphy (n=8). Elevated ESR (>30 mm/h) was the clinical finding that best predicted pelvic osteomyelitis or pyomyositis. Pelvic MR should be performed to rule out pelvic osteomyelitis or pyomyositis in children with acute hip pain, ESR of more than 30 mm/h, and no evidence of septic hip.

Risk factors for early radiographic changes of tibiofemoral osteoarthritis.

OBJECTIVE: To evaluate the risk factors for early radiographic changes of knee osteoarthritis. SUBJECTS: (n = 114) with unilateral or bilateral grade 0-1 knee osteoarthritis underwent x ray examination of the knees (semiflexed anteroposterior view) and assessment with the Western Ontario and McMaster Universities (WOMAC) Osteoarthritis Index at baseline and 30 months later. Severity of joint space narrowing (JSN) and osteophytosis were graded in randomly ordered serial radiographs by two readers, blinded to the sequence of the films, using standard pictorial atlases. RESULTS: The odds of an initial appearance of radiographic features of knee osteoarthritis at month 30 were more than threefold greater in African Americans than in whites (osteophytosis: odds ratio (OR) 3.30, 95% confidence interval (CI) 1.04 to 10.54; JSN: OR 3.49, 95% CI 1.16 to 10.68). In addition, the appearance of osteophytosis was positively related to baseline stiffness (OR 1.91/2.1 points on the 2-10 WOMAC scale, 95% CI 1.29 to 2.82). CONCLUSIONS: The distinction between incident and established, but early, radiographic knee osteoarthritis is difficult because of the limits to which all possible evidence of the disease can be ruled out in a conventional baseline knee radiograph. Nonetheless, our finding that African Americans were at greater risk of early osteophytosis and JSN than other subjects differs from the results of our previous analysis of risk factors for progressive knee osteoarthritis in the same subjects. The development of osteophytes also was associated with joint stiffness. Future investigations should focus on the systemic and local influences that these ostensible risk factors represent.

Optimizing imaging techniques in the postoperative patient.

Postoperative patients may develop complications requiring imaging. Although any imaging technique can be used to investigate these patients, the presence of metal hardware in the region of interest may distort the image and interfere with diagnosis. It is important to understand why this distortion occurs and how to compensate for it. Because some of the most common cross-sectional imaging methods used to image this patient population are computed tomography (CT) and magnetic resonance imaging (MRI), this article focuses on these imaging methods. Metal-related artifacts on CT depend on the hardware alloy, the geometry of the hardware, and the location of the hardware relative to the region of interest. The artifacts may be reduced or eliminated by altering the scan technique, changing the patient position, selecting a smoother CT reconstruction algorithm, and by creating thicker slice multiplanar reformations. Like CT, metal artifacts at MR imaging depend on the type of hardware alloy. Hardware-related artifacts at MR imaging can be reduced by using appropriate pulse sequences, such as fast or turbo spin echo and inversion recovery. Additionally, important pulse sequence modifications that are addressed here include manipulation of the receiver bandwidth and orientation of the frequency encode axis.

Multichannel CT: evaluating the spine in postoperative patients with orthopedic hardware.

Evaluating the spine in patients with metal orthopedic hardware is challenging. Although the effectiveness of conventional computed tomography (CT) can be limited by severe beam-hardening artifacts, the evolution of multichannel CT in recent years has made available new techniques that can help minimize these artifacts. Multichannel CT allows faster scanning times, resulting in reduced motion artifacts; thinner sections, with which it is possible to create a scanned volume of isotropic voxels with equivalent image resolution in all planes; and the generation of a higher x-ray tube current, which may result in better penetration of metal hardware and reduction of artifacts. Although 140 kVp and high milliamperage-second exposure are recommended for imaging patients with hardware, caution should always be exercised, particularly in children, young adults, and patients undergoing multiple examinations. The acquisition of multiplanar reformatted images in the axial, sagittal, coronal, and oblique planes and of three-dimensional volume-rendered images optimizes image interpretation. Wide window settings are best for reviewing images when hardware is present. The integrity of hardware is best assessed with multiplanar average intensity projection. Soft-tissue structures are best visualized by interactively varying the window width and level settings. Implementation of these techniques can yield diagnostic-quality images and aid in patient treatment.

Acetaminophen, like conventional NSAIDs, may reduce synovitis in osteoarthritic knees.

OBJECTIVE: To determine the extent to which treatment of patients with symptomatic knee osteoarthritis (OA) with non-steroidal anti-inflammatory drugs (NSAIDs) and acetaminophen (ACET) reduces total effusion volume and synovial tissue volume, as quantified by magnetic resonance imaging (MRI). METHODS: Sequential pilot studies used subjects whose knee OA was treated with NSAIDs (n=10) or with ACET or=15 of 25 on the Western Ontario and McMaster Universities' pain scale underwent l.5T MRI. Effusion was quantified in axial short tau inversion recovery images; to measure synovial tissue volume, fat-suppressed T1-weighted axial images were obtained 3 min after i.v. injection of gadolinium contrast. After the initial MRI examination, patients resumed their customary pain medications until the severity of knee pain returned to baseline, when pain was again measured and the MRI was repeated. RESULTS: Pain severity after washout was similar in subjects taking ACET and NSAIDs. Reinstitution of ACET resulted in a 50% decrease in the mean of pain scores (P=1.7 x 10(-12)) that was comparable with that seen after the reinstitution of NSAID (49%, P=6.0 x 10(-7)). The mean total effusion volume measured during the flare of knee pain induced by the withdrawal of the two drugs was comparable (ACET 16.9 ml, NSAID 16.2 ml; P=0.884). Significant decreases in mean total effusion volume were observed after reinstitution of both ACET (-4.5 ml, P=0.009) and NSAID (-3.3 ml, P=0.013); the difference between drugs was not significant. Analyses of synovial volume yielded similar results. CONCLUSION: While uncontrolled and derived from small samples, these data suggest that ACET may have a significant anti-inflammatory effect in patients with knee OA, comparable with that achieved with NSAIDs, possibly through an effect on neurogenic inflammation. Joint pain is the clinical feature of OA that most often leads the affected individual to seek medical attention. Because many patients with OA improve symptomatically with the use of NSAIDs, it has been widely assumed that the pain of OA is due to synovial inflammation. However, the origins of OA pain are numerous and may vary from patient to patient and, within the same subject, from visit to visit. Although the articular cartilage is usually the site of the most obvious pathological changes in this disease, it is aneural and, therefore, is not the source of joint pain. However, in addition to the synovium, the subchondral bone, joint capsule, osteophytes, menisci, ligaments, periarticular tendons, entheses and bursae all contain nociceptive nerve endings, stimulation of which by chemical or physical mediators may be a basis for OA pain.

Multichannel CT Imaging of Orthopedic Hardware and Implants.

The introduction of multichannel CT scanners provides both radiologists and surgeons with a new tool to image patients with orthopedic hardware. The key parameters that have made it possible to image the implants and the surrounding bone with multichannel CT are the higher available technical factors (kVp and mAs) coupled with the ability to acquire thin slices over a large scan region. These properties make it possible to produce high-quality multiplanar reformations that facilitate visualization of the orthopedic device and the surrounding bone. An important consideration for multichannel CT imaging of hardware is the reduction of cone beam artifacts caused by the geometry of multichannel CT scanners. This artifact is reduced by using a narrower x-ray beam collimation and a low pitch setting. This article discusses CT scan parameters and image postprocessing used at our institution and illustrates common clinical problems encountered when imaging implanted orthopedic devices. These include fracture healing, loosening of joint prostheses, evaluation of particle disease, and the use of CT for preoperative planning in revision arthroplasty.

Effects of doxycycline on progression of osteoarthritis: results of a randomized, placebo-controlled, double-blind trial.

OBJECTIVE: To confirm preclinical data suggesting that doxycycline can slow the progression of osteoarthritis (OA). The primary outcome measure was joint space narrowing (JSN) in the medial tibiofemoral compartment. METHODS: In this placebo-controlled trial, obese women (n = 431) ages 45-64 years with unilateral radiographic knee OA were randomly assigned to receive 30 months of treatment with 100 mg doxycycline or placebo twice a day. Tibiofemoral JSN was measured manually in fluoroscopically standardized radiographic examinations performed at baseline, 16 months, and 30 months. Severity of joint pain was recorded at 6-month intervals. RESULTS: Seventy-one percent of all randomized subjects completed the trial. Radiographs were obtained from 85% of all randomized subjects at 30 months. Adherence to the dosing regimen was 91.8% among subjects who completed the study per protocol. After 16 months of treatment, the mean +/- SD loss of joint space width in the index knee in the doxycycline group was 40% less than that in the placebo group (0.15 +/- 0.42 mm versus 0.24 +/- 0.54 mm); after 30 months, it was 33% less (0.30 +/- 0.60 mm versus 0.45 +/- 0.70 mm). Doxycycline did not reduce the mean severity of joint pain, although pain scores in both treatment groups were low at baseline and remained low throughout the trial, suggesting the presence of a floor effect. However, the frequency of followup visits at which the subject reported a > or = 20% increase in pain in the index knee, relative to the previous visit, was reduced among those receiving doxycycline. In contrast, doxycycline did not have an effect on either JSN or pain in the contralateral knee. In both treatment groups, subjects who reported a > or = 20% increase in knee pain at the majority of their followup visits had more rapid JSN than those whose pain did not increase. CONCLUSION: Doxycycline slowed the rate of JSN in knees with established OA. Its lack of effect on JSN in the contralateral knee suggests that pathogenetic mechanisms in that joint were different from those in the index knee.

Pitfalls in the accurate measurement of joint space narrowing in semiflexed, anteroposterior radiographic imaging of the knee.

OBJECTIVE: Computerized measurement of changes in joint space width (JSW) on serial radiographs of the knee in the semiflexed, anteroposterior (SF-AP) view has been used recently as a primary outcome measure in clinical trials of disease-modifying osteoarthritis drugs (DMOADs). In the use of fluoroscopy to achieve reproducible alignment of the medial tibial plateau and x-ray beam, the SF-AP radiographic protocol affords greater sensitivity in the detection of joint space narrowing (JSN) than that achieved by conventional radiographic positioning techniques. However, the utility of the SF-AP view is compromised by the variation in x-ray penetration in each examination, which may confound the correction of the automated measurement of JSW for the radiographic magnification inherent in an AP view of the knee. A recent DMOAD trial using the SF-AP protocol showed an improbable increase in JSW of > or =0.50 mm (i.e., greater than the measurement error). The present report provides an analysis of this problem, and the study aim was to demonstrate that substitution of the automated estimates of JSW with precise manual measurements can markedly reduce the problem attributable to radiographic magnification. METHODS: SF-AP radiographs were obtained at baseline and at 16 months and 30 months thereafter from subjects enrolled in a 6-center DMOAD trial. For each examination, a 6.35-mm steel ball was affixed to the skin over the head of the fibula to permit estimation of the percentage of radiographic magnification (%Mag) and correction of JSW measurements. Measurements of the minimum interbone distance (IBD) in the medial tibiofemoral compartment and the %Mag were obtained by an automated method (edge detection) and manually. Combinations of automated and manual measurements of the IBD and %Mag in estimates of magnification-corrected JSW were compared with respect to their reproducibility, agreement, and sensitivity to JSN. RESULTS: With fully automated measurements, variations in x-ray penetration in analog radiographs and edge enhancement in digital radiographs resulted in the computer "seeing" a metal ball whose diameter was artifactually reduced, resulting in an inflated measurement of JSW. Use of manual measurement of the IBD and %Mag largely eliminated these problems and reduced, from 16% to 2%, the frequency of knees exhibiting an increase in JSW > or =0.50 mm. In 14 of the 15 knees in which a significant increase in JSW was noted with the manual method, this increase in JSW could be explained by the development of significant lateral compartment narrowing during the study or poor alignment of the medial plateau. CONCLUSION: Although automated and manual methods of JSW measurement of the knee in the SF-AP view possess comparable intrareader reproducibility, the manual method is less susceptible to technical factors that affect the correction of raw JSW estimates for radiographic magnification. Until we can identify practical, effective solutions to these technical problems, use of any radiographic protocol involving AP imaging of the knee in a DMOAD trial must be viewed with caution.

Application of multidetector CT in skeletal trauma.

Multidetector computed tomography (MDCT) has improved our ability to image patients with skeletal trauma. The chief advantages of this technology include the extremely rapid scan times, the ability to produce very-high-quality multiplanar reformations, and the ability to reprocess raw data quickly and easily. Unlike soft tissue imaging, CT of bony structures requires high spatial resolution. Each joint in the body presents a unique challenge, and guidelines for imaging of each of the major joints is discussed throughout this article. In general, use of the thinnest slice width and a bone-reconstruction algorithm maximizes image quality. Imaging of larger joints such as the shoulder and hip requires slightly thicker slices to ensure reasonable image quality, particularly if surface rendering is to be performed. The demonstration of fracture line extension to articular surfaces is a key function of imaging, and image postprocessing is an integral component of high-resolution joint imaging. The introduction of MDCT has enabled submillimeter slice widths, ensuring unparalleled joint visualization in multiple planes from a single scan acquisition.

Three-dimensional volume rendering of the tendons of the ankle and foot.

Three-dimensional (3D) rendering is the process of creating two-dimensional (2D) images that convey the 3D relationships of an object or objects. In the past 10 years, the use of volume-rendering (VR) images has become a commonly used method of 3D display. The improved data sets that result from spiral and multidetector computed tomography, improved software, and more powerful workstations significantly improve radiologists' ability to create these images. The process by which these images are obtained is described. It is possible to simultaneously demonstrate the tendons and bones of the ankle and hindfoot using VR because of significant attenuation differences among the soft tissue, tendons, and bone: fat approximately -100, muscle approximately 30, tendon approximately 90, and bone approximately 250 to 500 Hounsfield units. These 3D images can be helpful in the care of patients with ankle/foot deformities resulting from trauma, idiopathic disorders, and arthritis. These images present a global image that provides improved understanding of the relationships of the bones and adjacent tendons.

CT with 3D rendering of the tendons of the foot and ankle: technique, normal anatomy, and disease.

Three-dimensional rendering of computed tomographic data with volume rendering (VR), shaded surface display (SSD), and maximum intensity projection has been performed for over 20 years. In the foot and ankle, no one image reformatting technique is satisfactory for displaying every anatomic relationship or disease process. Two-dimensional multiplanar reformatted (MPR) images are the basic images used for diagnosis. MPR images are especially useful for identifying small fractures. VR is useful for demonstrating the relationships between ankle tendons and the underlying osseous structures, and SSD is useful when fractures extend to the articular cortex and a disarticulated view is desired. Three-dimensional images are helpful in patients with congenital deformities, arthritis, and trauma.