Increasing Rates of Imaging in Failed Back Surgery Syndrome Patients: Implications for Spinal Cord Stimulation.

BACKGROUND: Failed back surgery syndrome (FBSS) has a high incidence following spinal surgery, is notoriously refractory to treatment, and results in high health care utilization. Spinal cord stimulation (SCS) is a well-accepted modality for pain relief in this population; however, until recently magnetic resonance imaging (MRI) was prohibited due to risk of heat conduction through the device. OBJECTIVES: We examined trends in imaging use over the past decade in patients with FBSS to determine its impact on health care utilization and implications for patients receiving SCS. STUDY DESIGN: Retrospective. SETTING: Inpatient and outpatient sample. METHODS: We identified patients from 2000 to 2012 using the Truven MarketScan database. Annual imaging rates (episodes per 1000 patient months) were determined for MRI, computed tomography (CT) scan, x-ray, and ultrasound. A multivariate Poisson regression model was used to determine imaging trends over time, and to compare imaging in SCS and non-SCS populations. RESULTS: A total of 311,730 patients with FBSS were identified, of which 5.17% underwent SCS implantation (n = 16,118). The median (IQR) age was 58.0 (49.0 - 67.0) years. Significant increases in imaging rate ratios were found in all years for each of the modalities. Increases were seen in the use of CT scans (rate ratio [RR] = 3.03; 95% confidence interval [CI]: 2.79 - 3.29; P < 0.0001), MRI (RR = 1.73; 95% CI: 1.61 - 1.85; P < 0.0001), ultrasound (RR = 2.00; 95% CI: 1.84 - 2.18; P < 0.0001), and x-ray (RR = 1.10; 95% CI: 1.05 - 1.15; P < 0.0001). Despite rates of MRI in SCS patients being half that in the non-SCS group, these patients underwent 19% more imaging procedures overall (P < 0.0001). SCS patients had increased rates of x-ray (RR = 1.27; 95% CI: 1.25 - 1.29), CT scans (RR = 1.32; 95% CI: 1.30 - 1.35), and ultrasound (RR = 1.10; 95% CI: 1.07 - 1.13) (all P < 0.0001). LIMITATIONS: This study is limited by a lack of clinical and historical variables including the complexity of prior surgeries and pain symptomatology. Miscoding cannot be precluded, as this sample is taken from a large nationwide database. CONCLUSIONS: We found a significant trend for increased use of advanced imaging modalities between the years 2000 and 2012 in FBSS patients. Those patients treated with SCS were 50% less likely to receive an MRI (as expected, given prior incompatibility of neuromodulation devices), yet 32% and 27% more likely to receive CT and x-ray, respectively. Despite the decrease in the use of MRI in those patients treated with SCS, their overall imaging rate increased by 19% compared to patients without SCS. This underscores the utility of MR-conditional SCS systems. These findings demonstrate that imaging plays a significant role in driving health care expenditures. This is the largest analysis examining the role of imaging in the FBSS population and the impact of SCS procedures. Further studies are needed to assess the impact of MRI-conditional SCS systems on future trends in imaging in FBSS patients receiving neuromodulation therapies. Key words: Failed back surgery syndrome, spinal cord stimulation, imaging, health care utilization, MRI, chronic pain, back pain, neuromodulation.

Impact on the recall rate of digital breast tomosynthesis as an adjunct to digital mammography in the screening setting. A double reading experience and review of the literature.

OBJECTIVES: To estimate the impact on recall rate (RR) of digital breast tomosynthesis (DBT) associated with digital mammography (DM+DBT), compared to DM alone, evaluate the impact of double reading (DR) and review the literature. METHODS: Ethics committees approved this multicenter study. Patients gave informed consent. Women recalled from population-based screening reading were included. Reference standard was histology and/or ≥ 1 year follow up. Negative multiple assessment was considered for patients lost at follow up. Two blinded readers (R1, R2) evaluated first DM and subsequently DM+DBT. RR, sensitivity, specificity, accuracy, positive and negative predictive values (PPV, NPV), were calculated for R1, R2, and DR. Cohen κ and χ(2) were used for R1-R2 agreement and RR related to breast density. RESULTS: We included 280 cases (41 malignancies, 66 benign lesions, and 173 negative examinations). The RR reduction was 43% (R1), 58% (R2), 43% (DR). Sensitivity, specificity, accuracy, PPV and NPV were: 93%, 67%, 71%, 33%, 98% for R1; 88%, 73%, 75%, 36%, 97% for R2; 98%, 55%, 61%, 27%, 99% for DR. The agreement was higher for DM+DBT (κ=0.459 versus κ=0.234). Reduction in RR was independent from breast density (p=0.992). CONCLUSION: DBT was confirmed to reduce RR, as shown by 13 of 15 previous studies (reported reduction 6-82%, median 31%). This reduction is confirmed when using DR. DBT allows an increased inter-reader agreement.

The influence of spatial variation in chromatin density determined by X-ray tomograms on the time to find DNA binding sites.

In this work, we examine how volume exclusion caused by regions of high chromatin density might influence the time required for proteins to find specific DNA binding sites. The spatial variation of chromatin density within mouse olfactory sensory neurons is determined from soft X-ray tomography reconstructions of five nuclei. We show that there is a division of the nuclear space into regions of low-density euchromatin and high-density heterochromatin. Volume exclusion experienced by a diffusing protein caused by this varying density of chromatin is modeled by a repulsive potential. The value of the potential at a given point in space is chosen to be proportional to the density of chromatin at that location. The constant of proportionality, called the volume exclusivity, provides a model parameter that determines the strength of volume exclusion. Numerical simulations demonstrate that the mean time for a protein to locate a binding site localized in euchromatin is minimized for a finite, nonzero volume exclusivity. For binding sites in heterochromatin, the mean time is minimized when the volume exclusivity is zero (the protein experiences no volume exclusion). An analytical theory is developed to explain these results. The theory suggests that for binding sites in euchromatin there is an optimal level of volume exclusivity that balances a reduction in the volume searched in finding the binding site, with the height of effective potential barriers the protein must cross during the search process.

Dimensional accuracy and details of the panoramic cross-sectional tomographic images: an in vitro study.

INTRODUCTION: Transversal slicing system (TSS) of Planmeca PM 2002 CC is a tomographic technique which enables us to take cross-sectional views of jaws. Tomographic imaging modalities are commonly applied to acquire cross-sectional images of the jaws for preimplant assessment of bone. Among the available tomographic imaging modalities, panoramic radiography is the most accessible imaging system. MATERIALS AND METHODS: Study was conducted using 25 mandibles, out of these five were used for linear dimensional accuracy measurement and the rest 20 were utilized to study the details within the mandible. Study was aimed to evaluate dimensional stability in the images using different parameters, such as determination of direction of slice, determination of horizontal and vertical magnification, angular distortion, three dimensional distortion and determination of details. RESULTS: For the direction of slice and for determination of horizontal and vertical magnification change in + 5º to - 5º was in acceptable limit. In determination of details, it was found that there was great discrepancy in readings given by nonradiologist which offset the mean value which was attributed to lack of training for interpretation of the observers. CONCLUSION: 99% of the readings were in the clinically acceptable limits. CLINICAL SIGNIFICANCE: The easy availability, use of routine equipment, the low cost, low radiation dose for cross-sectional radiography make the TSS most preferred modality.

Assessment of the anterior maxilla in orthodontic patients using upper anterior occlusal radiographs and dental panoramic tomography: a comparison.

OBJECTIVE: The aim of this study was to establish if dental panoramic tomographic (DPT) radiographs provide a reliable means of assessing the anterior maxilla in new orthodontic patients. STUDY DESIGN: Two hundred fifty pairs of upper anterior occlusal (UAO) and DPT radiographs were randomly selected from the records of new orthodontic patients. Ten observers each rated 50 pairs of radiographs for specific risk factors as well as for a measure of adequacy. Correlations between the 2 radiograph types and inter/intraobserver reliability were computed using Cohen kappa test. RESULTS: Intraobserver reliability was good for detection of impacted teeth/supernumeraries/periapical pathology (kappa = 0.711-1.0). Reliability was more variable for the specific root morphologies, with blunt and bent roots being reassessed as such most reliably (kappa = 0.259-0.533). There was low interobserver reliability (kappa = 0.327 for UAO and kappa = 0.223 for DPT) for "normal" or "not normal" root morphology. For every variable, however, the interexaminer agreement was higher when using UAO radiographs rather than DPTs. Observers were best able to agree on the diagnosis of eroded/resorbed roots on the UAO (kappa = 0.402) and blunt roots (kappa = 0.303) on the DPT radiographs. With UAO as the gold (reference) standard for grading root morphology, DPT had a sensitivity of 45.6% and a specificity of 71.4% for detecting abnormal root form. Risk factors were more likely to be detected on the UAO radiographs than the DPTs. DPTs had a poor ability to detect abnormal root form. DPTs were more likely to be rated as "inadequate" than UAO radiographs. On 6 occasions, supernumerary teeth that were observed on the UAO were missed on the DPT. CONCLUSION: The DPT is not an accurate means of screening the anterior maxilla prior to orthodontic treatment.

Statistical properties of X-ray phase-contrast tomography.

Quantitative in-line X-ray phase-contrast tomography methods seek to reconstruct separate images that depict an object's absorption and real-valued refractive index distributions. They hold great promise for biomedical applications due to their ability to distinguish soft tissue structures based on their complex X-ray refractive index values. In this work, we investigate the second-order statistical properties of images in phase-contrast tomography and describe how they are distinct from those associated with conventional absorption-based tomography.

Utilization of preoperative imaging in uterine cancer patients.

OBJECTIVE: Improvements in imaging technology over time have led to its increasingly widespread use in health care, even when the imaging may not be indicated. This study evaluates patterns of preoperative ultrasound, CT and MRI use among uterine cancer patients in Ontario. METHODS: This population-based study identified women diagnosed with uterine malignancy from 1995-2005 in the Ontario Cancer Registry. Record linkages were made to other healthcare databases to characterize residence, socioeconomic status, comorbidities, and timing of investigations surrounding diagnosis. RESULTS: We identified 12,522 women who received surgery for uterine adenocarcinoma or sarcoma, of which 9145 (73%) had a preoperative ultrasound, and 1148 (9.2%) had a preoperative CT and/or MRI. Over 10 years, the rate of CT use increased 4.5-fold while MRI use increased 10.6-fold. There were no significant differences in CT/MRI use among patients with increased comorbidities, urban residence or socioeconomic status. Higher rates of CT/MRI use were associated with non-endometrioid high-risk histology (33.5% vs 14.6%, p<0.0001). Median time from ultrasound to surgery was 11.6 weeks. Time from diagnosis to surgery was 2 weeks longer if a preoperative CT/MRI was done. Half of these tests were ordered by non-gynecologists. CONCLUSIONS: The rate of preoperative CT and MRI use in patients with uterine cancer has increased twice as much as the reported rate in cancer patients overall. Given the questionable utility of preoperative CT/MRI in this disease, guidelines should be developed for use of these imaging tests in uterine cancer, especially when use is associated with a delay in surgery.

The role of PET/CT in the management of patients with cervical cancer: practice patterns of the members of the Society of Gynecologic Oncologists.

OBJECTIVES: Recent data has highlighted the role of PET/CT in the pretreatment evaluation and follow-up of patients with cervical cancer. The objective of our study was to assess the acceptance of PET/CT into the management of patients with cervical cancer. We also explored potential barriers to the use of these imaging modalities in patients with cervical cancer. METHODS: A 14-item electronic questionnaire was initially sent to all working addresses of members of the SGO (n=1048). An opt-out option was offered. For members who did not respond within 3 weeks, a second electronic invitation was sent. A third request was finally sent to further improve response rates. Data were collected and analyzed using a commercially available on-line survey database. RESULTS: A total of 305 responses were collected for an overall 30% response rate. PET/CT appears to be widely available (99%) and accessible (75%) in most practices. Although 83% of members order routine CT imaging for all newly diagnosed cervical cancer cases, only 28% routinely order a PET/CT. Conversely, 64% would order a PET/CT for newly diagnosed patients with advanced disease or those at high risk for distant metastatic disease. Most members (82%) do not routinely use PET/CT to assess response to treatment. Twenty percent of members believe that no useful prognostic information can be obtained from routine use of molecular imaging in patients with cervical cancer. The most common barriers for use of PET/CT cited by members were perceived lack of third-party payer coverage and lack of scientific evidence. CONCLUSIONS: Despite clear scientific data supporting the use of PET/CT in patients with cervical cancer and apparent widespread availability, this imaging modality remains highly underutilized in clinical practice. Clarifying insurance coverage early in the evaluation process and replicating studies that have shown effectiveness of PET/CT in multiple roles may improve adoption of this potentially useful imaging modality.

A method for integrating facial cephalometry and corrected lateral tomography of the temporomandibular joint.

OBJECTIVES: To test the validity of an indirect method for obtaining the Frankfort horizontal (FH) plane and transferring it from the originating cephalogram to a tomogram. METHODS: One hundred and fifty-two corrected lateral tomograms from 38 individuals, taken before and after treatment, were used for this study. The tomograms were scanned and digitized. The angle between the FH plane and the long axis of the pterygopalatine fossa was measured on the reciprocal cephalograms. In addition, a tangent was drawn at the uppermost point of the glenoid fossa and parallel to the upper border of the film. Common variables regarding these two planes were measured and compared. RESULTS: It was found that the tangent to the fossa roof, parallel to the superior border of the film, did not coincide with the transferred cephalometric FH plane. Statistically significant differences were found between all variables for the two groups. CONCLUSIONS: In cases where integration of cephalometric and tomographic measurements are needed, the drawing of a tangent on the roof of the fossa is not a reliable method.

The accuracy and reliability of radiographic methods for the assessment of marginal bone level around oral implants.

OBJECTIVES: To determine the accuracy and reliability of radiographic methods for assessment of the marginal bone level around oral implants in human cadavers. METHODS: In three human cadavers two implants were placed according to the Instruction Manual for the Brånemark System. One implant was installed in the canine and one in the premolar region of the left mandible. For each implant, conventional and digital intra-oral paralleling radiography were performed. Digital images were printed with a Kodak 1200 Distributed Medical Imaging printer on blue transparent film, glossy and plain paper. Furthermore, digital scanographic, panoramic and tomographic images were taken with the Cranex Tome multimodal X-ray unit and printed on Agfa Drystar TM 1 B transparent films. All images were evaluated by five dental specialists. Data were statistically compared with real measurements of the marginal bone level on the human cadavers, performed by the same group of observers. Intra- and inter-observer variability were determined. RESULTS: Digital intra-oral images on glossy paper showed the smallest absolute difference between real and measured bone level, followed by digital intra-oral images on film and on plain paper, conventional intra-oral images on analogue film, panoramic, scanographic and tomographic images on film. The difference between real and radiographic measurements was not statistically significant (P>0.05) for all radiographic techniques. Intra- and inter-observer reproducibility was high for all techniques. CONCLUSIONS: The selected imaging techniques showed an acceptable accuracy for peri-implant bone level measurements with an overall error of less than 0.5 mm. Intra-oral images showed the smallest absolute differences.

Localisation of the mandibular canal using conventional spiral tomography: a human cadaver study.

For certain surgical procedures (e.g. placement of implants), an accurate localisation of the mandibular canal is of utmost importance to avoid injuries to the neurovascular bundle. The aim of the present study was to evaluate, on human fresh cadavers (n = 6), the accuracy of conventional spiral tomography for the localisation of the mandibular canal. By means of the Cranex TOME multifunctional unit (Orion Corporation Soredex, Helsinki, Finland), tomographic slices were taken at 3 different locations in the left posterior mandible (distal to the mental foramen). The mandibles were then sectioned at these 3 sites with a microtome. With a digital sliding caliper, the following 3 measurements were performed both on the tomograms and the bone sections at the three sites: 1) distance from the crest to mandibular canal, 2) overall bone height and 3) bone width. Overestimations of the distance to the mandibular canal (8/18) ranged from 1.05 to 0.10 mm and underestimations from 0.30 to 1.36 mm. The same number of over- and underestimations occurred for the bone height (1.14 to 0.14 mm and 0.15 to 1.40 mm, respectively). The bone width scored more overestimations (10/18), ranging from 1.40 to 0.12 mm, while underestimations ranged from 0.25 to 1.35 mm. From the present results, it is concluded that spiral tomography using the Cranex TOME multifunctional X-ray unit provides accurate information and sufficient detail for preoperative planning of implant placement in the posterior mandible.

The use of tomography for dental implant planning.

OBJECTIVES: To examine the use of tomography for dental implant planning. METHODS: A questionnaire was sent to oral radiology clinics in Sweden and to implantology clinics in different parts of the world with questions on selection criteria and techniques for, and frequency of, pre-implant tomography. Differences between mean values were assessed by t-test. A new method developed by the Swedish Radiation Protection Institute was used to assess radiation absorbed dose from CT. RESULTS: Tomography was used by 93.4% of the clinics, but there was marked variation both between and within different clinical situations. It was performed in all cases by 21% and the majority used it for the evaluation of the maxilla, the posterior mandible and in single implant cases. Small clinics (< 100 patients per year) used tomography frequently and clinics in Sweden significantly more often than those in other countries. The majority had changed their policy recently, using tomography more often. CT was used by 73% of respondents, mainly the small clinics. The majority of the large clinics (> 500 patients per year) used conventional tomography. The mean absorbed dose for CT scanning protocols was 65 mGy. The variation within and between different makes of CT was considerable. CONCLUSIONS: There are large variations in frequency of use of both conventional and computed tomography for dental implant planning by different clinics who also vary in the indications for their choice. A substantial factor influencing the technique chosen was its availability rather than clinical need.

Transverse tomosynthesis on a digital simulator.

The availability of digital radiographic imaging on simulators has led to the investigation of a number of new imaging possibilities, including digital linear tomography (tomosynthesis). It has been shown that a single set of projections in this case is sufficient to reconstruct images from multiple planes, including planes tilted with respect to the tube motion. The present work examines the feasibility of tomosynthetic image reconstruction in transverse planes using a CCD-based digital radiotherapy simulator with conventional isocentric rotational geometry. General transformation equations were derived to permit image reconstruction in arbitrary transverse planes. Transverse images of the skull section of the humanoid phantom have been generated using a 360 degrees gantry sweep. Bone, air, and radiographic markers are well resolved, but the image quality is poor due to the suboptimal scanning geometry available on the simulator.

Orthodontic residents' indications for use of the lateral TMJ tomogram and the posteroanterior cephalogram.

The purpose of this study was to determine the selection criteria used by orthodontic residents for ordering a corrected lateral tomogram (LT) of the temporomandibular joint (TMJ) and a posteroanterior cephalogram (PAC) for the diagnosis of patients needing orthodontic care. The impact of the radiographs on their treatment plans was also assessed. We conducted a study of the 144 new patients assigned to eight orthodontic residents during a two-year period. The residents responded through questionnaires describing their rationale for ordering the radiographs. A LT was ordered for twenty-eight (19 percent) of the patients. The most common reasons cited for requesting the LTs were TMJ clicking (67 percent) and pain (33 percent). The residents also perceived a need to order the LT for medico-legal protection in 85 percent of these cases. The LT tended not to have an impact on treatment planning. A PAC was ordered thirty-eight times (26 percent). The most common reasons cited by residents for ordering a PAC included clinical findings of facial asymmetry (41 percent) and maxillary airway anatomy (24 percent). Medico-legal protection was a perceived need in only 12 percent of the cases. While the PAC had no impact on treatment planning for 56 percent of the cases, they did define the transverse problems as dental or skeletal for 38 percent of the cases. Six patient traits were statistically associated with PAC requests: difficulty chewing, abnormal TMJ, TMJ clicking, facial asymmetry. crossbite, and midline discrepancy. The teaching of appropriate selection criteria for ordering these radiographs needs to be emphasized early in a resident's training.

Usefulness of tomography in the evaluation of patients with temporomandibular disorders: a retrospective clinical study.

OBJECTIVES: To evaluate the effect of temporomandibular joint tomography on the diagnosis and management of temporomandibular disorders and to determine whether there were any clinical predictors of usefulness of tomography in providing new information helpful in the treatment of these patients. STUDY DESIGN: The charts of 116 patients with temporomandibular joint tomograms were reviewed retrospectively for presenting signs and symptoms, initial clinical diagnosis, and alterations in diagnosis and management as a result of tomography. RESULTS: Common clinical diagnoses included osteoarthrosis (54%) and internal derangement (42%). Tomography changed the diagnosis in 24%, mainly adding or subtracting osteoarthrosis, and altered the management in 17%. Most of the latter were minor changes in treatment recommendations. There were few clinical variables that were related to whether tomography changed diagnosis or management. CONCLUSIONS: Tomography seems to have a minimal effect on the diagnosis or management of temporomandibular disorders based on the results of this retrospective study.

Skeletal muscle mass: evaluation of neutron activation and dual-energy X-ray absorptiometry methods.

Although skeletal muscle (SM) is a major body component, whole body measurement methods remain limited and inadequately investigated. The aim of the present study was to evaluate the Burkinshaw in vivo neutron activation analysis (IVNA)-whole body 40K-counting and dual-energy X-ray absorptiometry (DXA) methods of estimating SM by comparison to adipose tissue-free SM measured using multiscan computerized axial tomography (CT). In the Burkinshaw method the potassium-to-nitrogen ratios of SM and non-SM lean tissue are assumed constant; in the DXA method the ratio of appendicular SM to total SM is assumed constant at 0.75. Seventeen healthy men [77.5 +/- 13.8 (SD) kg body wt] and eight men with acquired immunodeficiency syndrome (AIDS; 65.5 +/- 7.6 kg) completed CT, IVNA, and DXA studies. SM measured by CT was 34.4 +/- 6.2 kg for the healthy subjects and 27.2 +/- 4.0 kg for the AIDS patients. Compared with CT, the Burkinshaw method underestimated SM by an average of 6.9 kg (20.1%, P = 0.0001) and 6.3 kg (23.2%, P = 0.01) in the healthy men and the men with AIDS, respectively. The DXA method minimally overestimated SM in both groups (2.0 kg and 5.8% in healthy men, P = 0.001; 1.4 kg and 5.1% in men with AIDS, P = 0.16). This overestimate could be explained by a higher actual than assumed ratio of DXA-measured appendicular SM to total body SM (actual = 0.79 +/- 0.05, assumed = 0.75). The current study results reveal that large errors are present in the Burkinshaw SM method and that substantial refinements in the models that form the basis of this IVNA approach are needed. The model on which the DXA-SM method is based also needs further minor refinements, but this is a promising in vivo approach because of less radiation exposure and lower cost than the IVNA and CT methods.

Clinical and radiological findings related to treatment outcome in patients with temporomandibular disorders.

OBJECTIVES: To test the hypothesis that the outcome of temporomandibular disorders (TMD) is not influenced by condylar position, asymmetry, angle or structural bone changes. METHODS: Eighty consecutive patients (60 women, 20 men) with an age range of 6-81 years, referred to the Department of Stomatognathic Physiology, were included in the study. The patients were clinically and radiologically examined before and at least 1 year after treatment. RESULTS: The most common clinical diagnoses among the patients were TMD with a neuromuscular background in 35% and osteoarthritis in 21%. Seventy-two per cent of the patients were symptom-free or better, 24% unchanged and 1% worse 1 year or more after treatment. After treatment the bone structure of the TMJ was unchanged in 83% of the patients, in 12% erosions healed and in 5% erosions developed. Almost all patients had some degree of condylar displacement on tomography before treatment. In the majority the condylar position was unchanged after treatment. CONCLUSION: No single radiographic finding was found to be related to the treatment outcome and therefore plain radiography has a minor role in the management of TMD.

Efficacy of TMJ radiographs in terms of expected versus actual findings.

OBJECTIVES: The purpose of this study was to measure the amount of new information contributed by temporomandibular joint tomograms beyond that anticipated by the patient's clinical presentation. STUDY DESIGN: The results of a clinical examination and history, including a video of patient interview, and dental casts of 105 patients with a temporomandibular disorder were presented to a panel of general dentist evaluators with some experience in temporomandibular disorders. These evaluators then described the radiographic findings they anticipated. Lastly they examined temporomandibular joint tomograms for each of the study patients and scored their findings. RESULTS: The temporomandibular joint tomograms revealed unanticipated osseous changes in 61% of case judgments of condyles and 47% for the temporal bone or 34% and 22%, respectively, when subtle changes were excluded. Unexpected condyle positional findings were revealed in 31% of the patients. When stratified by clinical class, osteoarthritis and internal derangement, false-positive and false-negative interpretations were 12.1% and 25.5%, respectively, for osteoarthritis, and 12.2% and 17.3% for derangement. CONCLUSIONS: The fairly high rate of unexpected new osseous and positional findings supports the need for tomograms in patients with a clinical diagnosis of derangement or osteoarthritis.