General practitioner experiences using a low back pain management booklet aiming to decrease non-indicated imaging for low back pain

Background

Imaging is overused in the management of low back pain, resulting in overdiagnosis, increased healthcare utilisation, and increased costs. Few effective interventions to decrease inappropriate use have been developed and have typically not been developed using behaviour change theory. An intervention to reduce non-indicated imaging for low back pain was developed using behavioural change theory, incorporating a novel low back pain management booklet to facilitate patient education and reassurance. The aim of this study was to assess the adoption and feasibility of use of the developed intervention within clinical practice and to determine appropriate implementation strategies to address identified barriers to use.

Methods

Fourteen general medical practitioners were recruited and trained to use the booklet with low back pain patients over a minimum 5-month period. Quantitative data on use of the booklet were collected and analysed descriptively. Qualitative data on use of the booklet and training session were collected in general medical practitioner interviews and thematically analysed. Barriers to use were identified and mapped to suitable implementation strategies using the Behaviour Change Wheel.

Results

Practitioners used the booklet with 73 patients. The booklet was used with 63% of patients presenting with low back pain. Facilitators for using the booklet included patient’s requesting imaging and lower practitioner confidence in managing low back pain. Barriers included accessible storage and remembering to use the booklet. Implementation strategies were identified to increase adoption and feasibility of use, including development of a digital version of the booklet.

Conclusions

General medical practitioners reported that the low back pain management booklet and training were useful for clinical practice, particularly with patients requesting imaging. Barriers to use were identified and implementation strategies to address these barriers will be incorporated into future effectiveness studies. This study forms one of a series of studies to thoroughly develop and test an intervention to reduce non-indicated imaging for low back pain; a successful intervention would decrease healthcare costs and improve patient management.

Effect of combination inhaled therapy on ventilation distribution measured by SPECT/CT imaging in uncontrolled asthma

Asthma is characterized by heterogeneous ventilation as measured by three-dimensional ventilation imaging. Combination inhaled corticosteroid/long-acting β₂-agonist (ICS/LABA) treatment response is variable in asthma, and effects on regional ventilation are unknown. Our aims were to determine whether regional ventilation defects decrease after ICS/LABA treatment and whether small airways dysfunction predicts response in uncontrolled asthma. Twenty-two symptomatic participants with asthma underwent single-photon emission computed tomography (SPECT)/CT imaging with Technegas, before and after 8-wk fluticasone/formoterol (1,000/40 µg/day) treatment. Lung regions that were nonventilated, low ventilated, or well ventilated were calculated using an adaptive threshold method and were expressed as a percentage of total lung volume. Multiple-breath nitrogen washout (MBNW) was used to measure diffusion-dependent and convection-dependent small airways function (Sacin and Scond, respectively). Forced oscillation technique (FOT) was used to measure respiratory system resistance and reactance. At baseline and posttreatment, Scond z-score was related to percentage of nonventilated lung, whereas Sacin z-score was related to percentage of low-ventilated lung. Although symptoms, spirometry, FOT, and MBNW improved following treatment, there was no mean change in ventilation measured by SPECT. There was, however, a wide range of changes in SPECT ventilation such that greater percentage of nonventilated lung, older age, and higher Scond predicted a reduction in nonventilated lung after treatment. SPECT ventilation defects are overall unresponsive to ICS/LABA, but the response is variable, with improvement occurring when small airways dysfunction and ventilation defects are more severe. Persistent ventilation defects that correlate with Scond suggest that mechanisms such as non-ICS responsive inflammation or remodeling underlie these defects.NEW & NOTEWORTHY This study provides insights into the mechanisms of high-dose ICS treatment in uncontrolled asthma. Ventilation defects as measured by SPECT/CT imaging respond heterogeneously to increased ICS/LABA treatment, with improvement occurring when ventilation defects and impairment of convection-dependent small airways function are more severe. Persistent correlations between ventilation defects and measures of small airways function suggest the potential presence of ICS nonresponsive inflammation and/or remodeling.

Bone-Conducted oVEMP Latency Delays Assist in the Differential Diagnosis of Large Air-Conducted oVEMP Amplitudes

Background: A sensitive test for Superior Semicircular Canal Dehiscence (SCD) is the air-conducted, ocular vestibular evoked myogenic potential (AC oVEMP). However, not all patients with large AC oVEMPs have SCD. This retrospective study sought to identify alternate diagnoses also producing enlarged AC oVEMPs and investigated bone-conducted (BC) oVEMP outcome measures that would help differentiate between these, and cases of SCD.

Methods: We reviewed the clinical records and BC oVEMP results of 65 patients (86 ears) presenting with dizziness or balance problems who underwent CT imaging to investigate enlarged 105 dB nHL click AC oVEMP amplitudes. All patients were tested with BC oVEMPs using two different stimuli (1 ms square-wave pulse and 8 ms 125 Hz sine wave). Logistic regression and odds ratios were used to determine the efficacy of BC oVEMP amplitudes and latencies in differentiating between enlarged AC oVEMP amplitudes due to dehiscence from those with an alternate diagnosis.

Results: Fifty-three ears (61.6%) with enlarged AC oVEMP amplitudes were identified as having frank dehiscence on imaging; 33 (38.4%) had alternate diagnoses that included thinning of the bone covering (near dehiscence, n = 13), vestibular migraine (n = 12 ears of 10 patients), enlarged vestibular aqueduct syndrome (n = 2) and other causes of recurrent episodic vertigo (n = 6). BC oVEMP amplitudes of dehiscent and non-dehiscent ears were not significantly different (p > 0.05); distributions of both groups overlapped with the range of healthy controls. There were significant differences in BC oVEMP latencies between dehiscent and non-dehiscent ears for both stimuli (p < 0.001). A prolonged n1 125 Hz latency (>11.5 ms) was the best predictor of dehiscence (odd ratio = 27.8; 95% CI:7.0-111.4); abnormal n1 latencies were identified in 79.2% of ears with dehiscence compared with 9.1% of ears without dehiscence.

Conclusions: A two-step protocol of click AC oVEMP amplitudes and 125 Hz BC oVEMP latency measures optimizes the specificity of VEMP testing in SCD.

A Window Into the Whole Story: Temporal Bone Plasmacytoma Presenting With a Mobile Third Window

A 63-year-old man presented with imbalance when coughing due to a respiratory tract infection. He had a history of multiple myeloma with a plasmacytoma of the left temporal bone. Examination revealed a positive leftward head impulse test, no spontaneous nystagmus, left-beating positional nystagmus, and left-beating Valsalva-induced nystagmus. Videonystagmography, audiology, and comprehensive vestibular function tests revealed a subtotal left peripheral audio-vestibular loss. Temporal bone computed tomography showed an unchanged bony erosion of the left labyrinth from 2 years prior. Vertigo subsided after treatment of the respiratory tract infection. Although no tumor progression was evident, coughing had triggered a preexisting third mobile window to declare itself. Laryngoscope, 131:E966-E969, 2021.

Cerebellar Tissue Strain in Chiari Malformation with Headache

OBJECTIVE

The pathogenesis of Chiari malformation type 1 (CM-1)-associated Valsalva headache is unknown, but it may be caused by abnormal cerebellar tonsil tissue strain. Advances in cardiac-gated magnetic resonance imaging (MRI) techniques such as balanced fast-field echo (bFFE) allow quantification of the motion of anatomic structures and can be used to measure tissue strain. The current study investigated the relationship between Valsalva heachache and tonsillar motion in patients with CM-1.

METHODS

A retrospective review of patients with CM-1 who had undergone cardiac-gated bFFE MRI was performed. Headache symptoms were retrieved from the medical records. Anatomic landmarks were manually selected on the cine bFFE, and a validated motion-tracking software was used to assess motion over the cardiac cycle in patients at rest. For each patient, displacement, strain, and strain rate were calculated for 3 anatomic segments. Patients undergoing surgery were examined before and after surgery.

RESULTS

From 88 patients, a total of 108 bFFE sequences were analyzed. Valsalva headache was present in 50% of patients. Cerebellar tonsil displacement (P = 0.003), strain (P = 0.012), and maximum strain rate (P = 0.04) were reduced after surgery (n = 20). There was no statistically significant association between tissue motion and headache symptoms.

CONCLUSION

The results of this study do not support a relationship between cardiac cycle cerebellar strain and Valsalva headache in patients with CM-1. It is possible that cerebellar strain related to respiratory maneuvers is associated with headache in Chiari patients. Further investigation of tissue strain is warranted because it represents a potential biomarker for outcomes after surgery.

Imaging for low back pain: is clinical use consistent with guidelines? A systematic review and meta-analysis

BACKGROUND CONTEXT

The problem of imaging patients with low back pain (LBP) when it is not indicated is well recognized. The converse is also possible, although rarely considered. The extent of these two problems is presently unclear.

PURPOSE

This study aimed to estimate how commonly overuse, and also underuse, of imaging occurs in the management of LBP, and how appropriate use of imaging is assessed.

DESIGN

This is a systematic review and meta-analysis.

PATIENT SAMPLE

The sample comprised patients with LBP presenting to primary care.

OUTCOME MEASURES

Proportions of inappropriate referral, and inappropriate non-referral, for diagnostic imaging for LBP were the outcome measures.

METHODS

MEDLINE, EMBASE, and CINAHL were searched from January 1, 1995 to December 17, 2017. Two authors independently assessed study quality and extracted data. Meta-analyses were performed where appropriate, and strength of evidence was assessed using the Grading of Recommendations, Assessment, Development and Evaluation system.

RESULTS

Thirty-three studies were included. In patients referred for lumbar imaging, 34.8% (95% confidence interval [CI]: 27.1, 43.3) were judged inappropriate by the absence of red flags for serious pathology and 31.6% (95% CI: 28.3, 35.1) were judged inappropriate by the criteria of no clinical suspicion of pathology. In patients presenting for care, imaging was inappropriately performed in 27.7% of cases (95% CI: 21.3, 35.1) when judged by duration of episode, 9.0% of cases (95% CI: 7.4, 11.0) when judged by absence of red flags, and 7.0% (95% CI: 1.8, 23.3) when judged by no clinical suspicion of pathology. In patients presenting for care, imaging was not performed where appropriately indicated in 65.6% (95% CI: 51.8, 77.2) of patients who presented with red flags, and 60.8% (95% CI: 42.0, 76.8) with clinical suspicion of serious pathology.

CONCLUSIONS

Inappropriate imaging is common in LBP management, including both overuse in those where imaging is not indicated and underuse of imaging when it is indicated. Appreciating that both underuse and overuse can occur is fundamental to efforts to improve imaging practice to align with current guidelines and best evidence.

The integration of pharmacology and pathophysiology into locoregional chemotherapy delivery via mass fluid transfer

The prevailing paradigm of locoregional chemotherapy has been centred around delivering chemotherapy as close to the tumour as possible and in some cases incorporating vascular isolation techniques. Strategically, the development of these techniques has been rudimentary without consideration for the interdependencies between macrovascular manipulation and the microvascular effects. This review focuses on how new capabilities offered by recent advances in vascular access technology could be exploited to facilitate the mass fluid transfer (MFT) of anticancer agents to solid tumours. A haemodynamic model of MFT is proposed using the physical laws of fluid flow, flux, and diffusion that describe the microvascular effects anticancer agents may have upon tumours through the manipulation of macrovascular blood flow control. Finally, the possible applications of this technique for several organs are discussed.

Using behaviour change theory and preliminary testing to develop an implementation intervention to reduce imaging for low back pain

BACKGROUND

Imaging is overused in the management of low back pain (LBP). Interventions designed to decrease non-indicated imaging have predominantly targeted practitioner education alone; however, these are typically ineffective. Barriers to reducing imaging have been identified for both patients and practitioners. Interventions aimed at addressing barriers in both these groups concurrently may be more effective. The Behaviour Change Wheel provides a structured framework for developing implementation interventions to facilitate behavioural change. The aim of this study was to develop an implementation intervention aiming to reduce non-indicated imaging for LBP, by targeting both general medical practitioner (GP) and patient barriers concurrently.

METHODS

The Behaviour Change Wheel was used to identify the behaviours requiring change, and guide initial development of an implementation intervention. Preliminary testing of the intervention was performed with: 1) content review by experts in the field; and 2) qualitative analysis of semi-structured interviews with 10 GPs and 10 healthcare consumers, to determine barriers and facilitators to successful implementation of the intervention in clinical practice. Results informed further development of the implementation intervention.

RESULTS

Patient pressure on the GP to order imaging, and the inability of the GP to manage a clinical consult for LBP without imaging, were determined to be the primary behaviours leading to referral for non-indicated imaging. The developed implementation intervention consisted of a purpose-developed clinical resource for GPs to use with patients during a LBP consult, and a GP training session. The implementation intervention was designed to provide GP and patient education, remind GPs of preferred behaviour, provide clinical decision support, and facilitate GP-patient communication. Preliminary testing found experts, GPs, and healthcare consumers were supportive of most aspects of the developed resource, and thought use would likely decrease non-indicated imaging for LBP. Suggestions for improvement of the implementation intervention were incorporated into a final version.

CONCLUSIONS

The developed implementation intervention, aiming to reduce non-indicated imaging for LBP, was informed by behaviour change theory and preliminary testing. Further testing is required to assess feasibility of use in clinical practice, and the effectiveness of the implementation intervention in reducing imaging for LBP, before large-scale implementation can be considered.

Elevated plasma ferritin in elderly individuals with high neocortical amyloid-β load

Ferritin, an iron storage and regulation protein, has been associated with Alzheimer's disease (AD); however, it has not been investigated in preclinical AD, detected by neocortical amyloid-β load (NAL), before cognitive impairment. Cross-sectional analyses were carried out for plasma and serum ferritin in participants in the Kerr Anglican Retirement Village Initiative in Aging Health cohort. Subjects were aged 65-90 years and were categorized into high and low NAL groups via positron emission tomography using a standard uptake value ratio cutoff=1.35. Ferritin was significantly elevated in participants with high NAL compared with those with low NAL, adjusted for covariates age, sex, apolipoprotein E ɛ4 carriage and levels of C-reactive protein (an inflammation marker). Ferritin was also observed to correlate positively with NAL. A receiver operating characteristic curve based on a logistic regression of the same covariates, the base model, distinguished high from low NAL (area under the curve (AUC)=0.766), but was outperformed when plasma ferritin was added to the base model (AUC=0.810), such that at 75% sensitivity, the specificity increased from 62 to 71% on adding ferritin to the base model, indicating that ferritin is a statistically significant additional predictor of NAL over and above the base model. However, ferritin's contribution alone is relatively minor compared with the base model. The current findings suggest that impaired iron mobilization is an early event in AD pathogenesis. Observations from the present study highlight ferritin's potential to contribute to a blood biomarker panel for preclinical AD.

Prospective Comparison of Changes in Lumbar Spine MRI Findings over Time between Individuals with Acute Low Back Pain and Controls: An Exploratory Study

BACKGROUND AND PURPOSE

The clinical importance of lumbar MR imaging findings is unclear. This study was an exploratory investigation of whether lumbar spine MR imaging findings change more commonly during a 12-week period in individuals with acute low back pain compared with pain-free controls.

MATERIALS AND METHODS

Twenty individuals with recent-onset low back pain and 10 pain-free controls were recruited into an exploratory prospective cohort study. All participants had a lumbar spine MR imaging at baseline and repeat MR imaging scans at 1, 2, 6, and 12 weeks. The proportion of individuals who had MR imaging findings that changed during the 12-week period was compared with the same proportion in the controls.

RESULTS

In 85% of subjects, we identified a change in at least 1 MR imaging finding during the 12 weeks; however, the proportion was similar in the controls (80%). A change in disc herniation, annular fissure, and nerve root compromise was reported more than twice as commonly in the subjects as in controls (65% versus 30%, 25% versus 10%, and 15% versus 0%, respectively). Caution is required in interpreting these findings due to wide confidence intervals, including no statistical difference. For all other MR imaging findings, the proportions of subjects and controls in whom MR imaging findings were reported to change during 12 weeks were similar.

CONCLUSIONS

Changes in MR imaging findings were observed in a similar proportion of the low back pain and control groups, except for herniations, annular fissures, and nerve root compromise, which were twice as common in subjects with low back pain.

Cerebellar and hindbrain motion in Chiari malformation with and without syringomyelia

OBJECTIVE

The pathogenesis of syringomyelia associated with Chiari malformation type I (CM-I) is unclear. Theories of pathogenesis suggest the cerebellar tonsils may obstruct CSF flow or alter pressure gradients, or their motion might act as a piston to increase CSF pressure in the spinal subarachnoid space. This study was performed to measure cerebellar tonsillar and hindbrain motion in CM-I and assess the potential contributions to syrinx formation.

METHODS

Sixty-four CM-I patients and 25 controls were retrospectively selected from a clinical database, and all subjects had undergone cardiac-gated cine balanced fast-field echo MRI. There were a total of 36 preoperative CM-I scans, which consisted of 15 patients with and 21 patients without syringomyelia. Nineteen patients underwent paired pre- and postoperative imaging. Anteroposterior (AP) and superoinferior (SI) movements of the tip of the cerebellar tonsils, obex, fastigium of the fourth ventricle, pontomedullary junction, and cervicomedullary junction were measured. The distance between the fastigium and tip of the tonsils was used to calculate tonsillar tissue strain (Δi/i0).

RESULTS

CM-I patients had significantly greater cerebellar tonsillar motion in both the AP and SI directions than controls (AP +0.34 mm [+136%], p < 0.001; SI +0.49 mm [+163%], p < 0.001). This motion decreased after posterior fossa decompression (AP -0.20 mm [-33%], p = 0.001; SI -0.29 mm [-36%]; p < 0.001), but remained elevated above control levels (AP +56%, p = 0.021; SI +67%, p = 0.015). Similar trends were seen for all other tracked landmarks. There were no significant differences in the magnitude or timing of motion throughout the hindbrain between CM-I patients with and without syringomyelia. Increased tonsillar tissue strain correlated with Valsalva headaches (p = 0.03).

CONCLUSIONS

Cerebellar tonsillar motion may be a potential marker of CM-I and may have use in tailoring surgical procedures. The lack of association with syringomyelia suggests that tonsillar motion alone is not the driver of syrinx formation. Tonsillar tissue strain may play a part in the pathophysiology of Valsalva headaches.

Risk factors for a recurrence of low back pain

BACKGROUND CONTEXT

The clinical importance of lumbar pathology identified on magnetic resonance imaging (MRI) remains unclear. It is plausible that pathology seen on MRI is a risk factor for a recurrence of low back pain (LBP); however, to our knowledge, this has not been investigated by previous studies.

PURPOSE

The aim was to investigate whether lumbar pathology, identifiable on MRI, increases the risk of a recurrence of LBP.

STUDY DESIGN

This was a prospective inception cohort study with 1-year follow-up.

PATIENT SAMPLE

Seventy-six people who had recovered from an episode of LBP within the previous 3 months were included.

OUTCOME MEASURES

The primary outcome was time to recurrence of LBP, which was determined by contacting participants at 2-month intervals for 12 months.

METHODS

All participants underwent a baseline assessment including MRI scan and completion of a questionnaire, which assessed a range of potential risk factors for recurrence. Magnetic resonance imaging scans were reported for the presence of a range of MRI findings. The primary analysis investigated the predictive value of two clinical features (age and number of previous episodes) and six MRI findings (disc degeneration, high intensity zone, Modic changes, disc herniation, facet joint arthrosis, and spondylolisthesis) in a multivariate Cox regression model. We decided a priori that dichotomous predictors with hazard ratios (HRs) of greater than 1.5 or less than 0.67 would be considered potentially clinically important and justify further investigation.

RESULTS

Of the eight predictors entered into the primary multivariate model, three (disc degeneration, high intensity zone, and number of previous episodes) met our a priori threshold for potential importance. Participants with disc degeneration score greater than or equal to 3 (Pfirrmann scale) had a HR of 1.89 (95% confidence interval [CI] 0.42-8.53) compared with those without. Patients with high intensity zone had an HR of 1.84 (95% CI 0.94-3.59) compared with those without. For every additional previous episode, participants had an HR of 1.04 (95% CI 1.02-1.07).

CONCLUSIONS

We identified promising risk factors for a recurrence of LBP, which should be further investigated in larger trials. The findings suggest that pathology seen on MRI plays a potentially important role in recurrence of LBP.

Greater parallel heterogeneity of airway narrowing and airway closure in asthma measured by high-resolution CT

BACKGROUND

Heterogeneous airway narrowing and closure are characteristics of asthma. However, they have never been quantified by direct measurements of parallel sister airways obtained from image data, and the anatomical basis of these processes remains unknown.

METHODS

Seven normal and nine asthmatic subjects underwent high-resolution CT, before and after methacholine challenge. Mean lumen areas of the entire airways were measured in 28 and 24 parallel sister airway pairs (a pair of airways arising from the same bifurcation) respectively (range 1.0-8.7 mm diameter). Heterogeneous narrowing was defined as the median difference in percentage narrowing between parallel sister airways. Forced oscillatory respiratory resistance (Rrs) and spirometry were measured before and after methacholine challenge conducted while supine.

RESULTS

The airways of asthmatics were smaller at baseline, and following bronchoconstriction there were similar decreases in FEV1, increases in Rrs and mean narrowing of airways for asthmatic and non-asthmatic groups. Non-asthmatics required higher doses of methacholine than asthmatics to achieve the same changes. However, parallel heterogeneity (median (IQR) 33% (27-53%) vs 11% (9-18%), p<0.001) and airway closure (24.1% and 7.7%, p=0.001, χ(2)) were greater in asthmatics versus non-asthmatics.

CONCLUSION

We found clear evidence of differences in airway behaviour in the asthmatic group. Asthmatic airways were narrower at baseline and responded to inhaled methacholine by more heterogeneous narrowing of parallel sister airways and greater airway closure.

Liposuction for Advanced Lymphedema: A Multidisciplinary Approach for Complete Reduction of Arm and Leg Swelling

Purpose

This research describes and evaluates a liposuction surgery and multidisciplinary rehabilitation approach for advanced lymphedema of the upper and lower extremities.

Methods

A prospective clinical study was conducted at an Advanced Lymphedema Assessment Clinic (ALAC) comprised of specialists in plastic surgery, rehabilitation, imaging, oncology, and allied health, at Macquarie University, Australia. Between May 2012 and 31 May 2014, a total of 104 patients attended the ALAC. Eligibility criteria for liposuction included (i) unilateral, non-pitting, International Society of Lymphology stage II/III lymphedema; (ii) limb volume difference greater than 25 %; and (iii) previously ineffective conservative therapies. Of 55 eligible patients, 21 underwent liposuction (15 arm, 6 leg) and had at least 3 months postsurgical follow-up (85.7 % cancer-related lymphedema). Liposuction was performed under general anesthesia using a published technique, and compression garments were applied intraoperatively and advised to be worn continuously thereafter. Limb volume differences, bioimpedance spectroscopy (L-Dex), and symptom and functional measurements (using the Patient-Specific Functional Scale) were taken presurgery and 4 weeks postsurgery, and then at 3, 6, 9, and 12 months postsurgery.

Results

Mean presurgical limb volume difference was 45.1 % (arm 44.2 %; leg 47.3 %). This difference reduced to 3.8 % (arm 3.6 %; leg 4.3 %) by 6 months postsurgery, a mean percentage volume reduction of 89.6 % (arm 90.2 %; leg 88.2 %) [p < 0.001]. All patients had improved symptoms and function. Bioimpedance spectroscopy showed reduced but ongoing extracellular fluid, consistent with the underlying lymphatic pathology.

Conclusions

Liposuction is a safe and effective option for carefully selected patients with advanced lymphedema. Assessment, treatment, and follow-up by a multidisciplinary team is essential.

Effectiveness of interventions designed to reduce the use of imaging for low-back pain: a systematic review

BACKGROUND

Rates of imaging for low-back pain are high and are associated with increased health care costs and radiation exposure as well as potentially poorer patient outcomes. We conducted a systematic review to investigate the effectiveness of interventions aimed at reducing the use of imaging for low-back pain.

METHODS

We searched MEDLINE, Embase, CINAHL and the Cochrane Central Register of Controlled Trials from the earliest records to June 23, 2014. We included randomized controlled trials, controlled clinical trials and interrupted time series studies that assessed interventions designed to reduce the use of imaging in any clinical setting, including primary, emergency and specialist care. Two independent reviewers extracted data and assessed risk of bias. We used raw data on imaging rates to calculate summary statistics. Study heterogeneity prevented meta-analysis.

RESULTS

A total of 8500 records were identified through the literature search. Of the 54 potentially eligible studies reviewed in full, 7 were included in our review. Clinical decision support involving a modified referral form in a hospital setting reduced imaging by 36.8% (95% confidence interval [CI] 33.2% to 40.5%). Targeted reminders to primary care physicians of appropriate indications for imaging reduced referrals for imaging by 22.5% (95% CI 8.4% to 36.8%). Interventions that used practitioner audits and feedback, practitioner education or guideline dissemination did not significantly reduce imaging rates. Lack of power within some of the included studies resulted in lack of statistical significance despite potentially clinically important effects.

INTERPRETATION

Clinical decision support in a hospital setting and targeted reminders to primary care doctors were effective interventions in reducing the use of imaging for low-back pain. These are potentially low-cost interventions that would substantially decrease medical expenditures associated with the management of low-back pain.

Augmented active surface model for the recovery of small structures in CT

This paper devises an augmented active surface model for the recovery of small structures in a low resolution and high noise setting, where the role of regularization is especially important. The emphasis here is on evaluating performance using real clinical computed tomography (CT) data with comparisons made to an objective ground truth acquired using micro-CT. In this paper, we show that the application of conventional active contour methods to small objects leads to non-optimal results because of the inherent properties of the energy terms and their interactions with one another. We show that the blind use of a gradient magnitude based energy performs poorly at these object scales and that the point spread function (PSF) is a critical factor that needs to be accounted for. We propose a new model that augments the external energy with prior knowledge by incorporating the PSF and the assumption of reasonably constant underlying CT numbers.

Effect of weight loss on upper airway size and facial fat in men with obstructive sleep apnoea

BACKGROUND

Obstructive sleep apnoea (OSA) is commonly associated with obesity and can be improved by weight loss. Changes in upper airway size related to regional fat loss may mediate the improvement in OSA. This study aimed to assess changes in upper airway size and regional facial and abdominal fat with weight loss and their association with OSA improvement.

METHODS

Middle-aged obese men with moderate-to-severe OSA underwent a 24-week sibutramine-assisted weight loss trial. Polysomnography and CT of the head and neck were performed at baseline and 24 weeks. The upper airway lumen and facial and parapharyngeal fat were measured with image analysis software.

RESULTS

Post-intervention there was a significant reduction in weight (-7.8±4.2 kg, p<0.001) and apnoea-hypopnoea index (AHI) (-15.9±20.5 events/h, p<0.001). Velopharyngeal airway volume significantly increased from baseline (5.3±0.4 to 6.3±0.3 cm(3), p<0.01) and facial and paraphayngeal fat volume significantly reduced. A reduction in upper airway length was associated with improvement in AHI (r=0.385, p=0.005). The variance in AHI improvement was best explained by changes in upper airway length and visceral abdominal fat (R(2)=0.31, p=0.004).

CONCLUSIONS

Weight loss increases velopharyngeal airway volume, but changes in upper airway length appear to have a greater influence on the reduction in apnoea frequency. Inter-individual variability in the effects of weight loss on OSA severity cannot be explained in terms of changes in upper airway structure and local fat deposition alone.

A mathematical model of human semicircular canal geometry: a new basis for interpreting vestibular physiology

We report a precise, simple, and accessible method of mathematically measuring and modeling the three-dimensional (3D) geometry of semicircular canals (SCCs) in living humans. Knowledge of this geometry helps understand the development and physiology of SCC stimulation. We developed a framework of robust techniques that automatically and accurately reconstruct SCC geometry from computed tomography (CT) images and are directly validated using micro-CT as ground truth. This framework measures the 3D centroid paths of the bony SCCs allowing direct comparison and analysis between ears within and between subjects. An average set of SCC morphology is calculated from 34 human ears, within which other geometrical attributes such as nonplanarity, radius of curvature, and inter-SCC angle are examined, with a focus on physiological implications. These measurements have also been used to critically evaluate plane fitting techniques that reconcile many of the discrepancies in current SCC plane studies. Finally, we mathematically model SCC geometry using Fourier series equations. This work has the potential to reinterpret physiology and pathophysiology in terms of real individual 3D morphology.

Changes in regional adiposity and cardio-metabolic function following a weight loss program with sibutramine in obese men with obstructive sleep apnea

BACKGROUND

Although obstructive sleep apnea (OSA) is strongly linked with obesity, both conditions have been associated with increased cardiovascular risk including glucose intolerance, dyslipidemia, and hypertension independent of one another. Weight loss is known to improve both cardiovascular risk and OSA severity. The aim of this study was to evaluate cardiovascular and metabolic changes, including compartment-specific fat loss in obese OSA subjects undergoing a weight loss program.

DESIGN

Observational study.

PARTICIPANTS

93 men with moderate-severe OSA.

INTERVENTIONS

6-month open-label weight loss trial combining sibutramine (a serotonin and noradrenaline reuptake inhibitor) with a 600-kcal deficit diet and exercise.

MEASUREMENTS AND RESULTS

At baseline and following 6 months of weight loss, OSA was assessed together with CT-quantified intraabdominal and liver fat and markers of metabolic and cardiovascular function. At 6 months, weight loss and improvements in OSA were accompanied by improved insulin resistance (HOMA), increased HDL cholesterol, and reduced total cholesterol/HDL ratio. There were also reductions in measures of visceral and subcutaneous abdominal fat and liver fat. Reductions in liver fat and sleep time spent below 90% oxyhemoglobin saturation partly explained the improvement in HOMA (R2 = 0.18). In contrast, arterial stiffness (aortic augmentation index), heart rate, blood pressure, and total cholesterol did not change.

CONCLUSIONS

Weight loss with sibutramine was associated with improvements in metabolic and body composition risk factors but not blood pressure or arterial stiffness. Improved insulin resistance was partly associated with reductions in liver fat and hypoxemia associated with sleep apnea.

MRI of the vestibular nerve after selective vestibular neurectomy

CONCLUSION

In patients with Ménière's disease and persisting vertigo attacks after vestibular neurectomy (VNx) MRI of the vestibulocochlear nerve can identify residual vestibular nerve fibres that could be responsible for the vertigo attacks.

OBJECTIVE

To test if MRI of the vestibulocochlear nerve can corroborate the presence of residual vestibular nerve fibres in patients with persisting vertigo attacks and residual vestibular function after VNx.

MATERIALS AND METHODS

Vestibulocochlear nerve bundles of seven post-VNx unilateral Ménière's patients were imaged using 1.5 Tesla MRI with steady state free precession (SSFP) sequences. Reformatted MR images orthogonal to the vestibulocochlear nerve axis in internal auditory canal were compared on the VNx and intact sides. Vestibular function was assessed with caloric tests, three-dimensional head impulse tests and vestibular evoked myogenic potentials. Of the seven patients only one was asymptomatic (totally free of vertigo); six had continued to experience vertigo attacks, albeit not as long or as severe as before VNx.

RESULTS

On the VNx side, MRI showed intact facial and cochlear nerves in all seven patients. In the six symptomatic patients, although superior and inferior vestibular nerve bulk and signal were reduced, residual bulk suggestive of inferior vestibular nerve was evident, correlating with evidence of residual posterior canal function on impulsive testing in all six symptomatic patients. In the asymptomatic patient, superior and inferior vestibular nerves were absent on MRI and impulsive testing revealed no residual posterior canal function.

Airway dimensions measured from micro-computed tomography and high-resolution computed tomography

Volume averaging results in both over- and underestimation of airway dimensions when they are measured by high-resolution computed tomography (HRCT). The current authors calibrated computerised measurements of airway dimensions from HRCT against a novel three-dimensional micro-computed tomography (CT) standard, which has a 50-fold greater resolution, as well as against traditional morphometry. Inflation-fixed porcine lung cubes were scanned by HRCT and micro-CT. A total of 59 lumen area (Ai), 30 wall area (A(aw)) and 11 lumen volume (Vi) measurements were made. Ai was measured from the cut surface of 11 airways by morphometry. Airways in scanned images were matched using branching points. After calibration, the errors of Ai, A(aw) and Vi HRCT measurements were determined. The current authors found a systematic, size-dependent underestimation of Ai and overestimation of A(aw) from HRCT measurements. This was used to calibrate an HRCT measurement algorithm. The 95% limits of agreement of subsequent measurements were +/-3.2 mm2 for Ai, +/-4.3 mm2 for A(aw), and +/-11.2 mm3 for Vi with no systematic error. Morphometric measurements agreed with micro-CT (+/-2.5 mm2) without systematic error. In conclusion, micro-computed tomography image data from inflation-fixed airways can be used as calibration standards for three-dimensional lumen volume measurements from high-resolution computed tomography, while morphometry is acceptable for two-dimensional measurements. The image dataset could be used to validate other developmental three-dimensional segmentation algorithms.

Click-evoked vestibulo-ocular reflex

Background: An enlarged, low-threshold click-evoked vestibulo-ocular reflex (VOR) can be averaged from the vertical electro-oculogram in a superior canal dehiscence (SCD), a temporal bone defect between the superior semicircular canal and middle cranial fossa.

Objective: To determine the origin and quantitative stimulus–response properties of the click-evoked VOR.

Methods: Three-dimensional, binocular eye movements evoked by air-conducted 100-microsecond clicks (110 dB normal hearing level, 145 dB sound pressure level, 2 Hz) were measured with dual-search coils in 11 healthy subjects and 19 patients with SCD confirmed by CT imaging. Thresholds were established by decrementing loudness from 110 dB to 70 dB in 10-dB steps. Eye rotation axis of click-evoked VOR computed by vector analysis was referenced to known semicircular canal planes. Response characteristics were investigated with regard to enhancement using trains of three to seven clicks with 1-millisecond interclick intervals, visual fixation, head orientation, click polarity, and stimulation frequency (2 to 15 Hz).

Results: In subjects and SCD patients, click-evoked VOR comprised upward, contraversive-torsional eye rotations with onset latency of approximately 9 milliseconds. Its eye rotation axis aligned with the superior canal axis, suggesting activation of superior canal receptors. In subjects, the amplitude was less than 0.01°, and the magnitude was less than 3°/second; in SCD, the amplitude was up to 60 times larger at 0.66°, and its magnitude was between 5 and 92°/second, with a threshold 10 to 40 dB below normal (110 dB). The click-evoked VOR magnitude was enhanced approximately 2.5 times with trains of five clicks but was unaffected by head orientation, visual fixation, click polarity, and stimulation frequency up to 10 Hz; it was also present on the surface electro-oculogram.

Conclusion: In superior canal dehiscence, clicks evoked a high-magnitude, low-threshold, 9-millisecond-latency vestibulo-ocular reflex that aligns with the superior canal, suggesting superior canal receptor hypersensitivity to sound.

Determining the cross-sectional segmental anatomy of cadaveric human lungs

An investigation of the complex boundaries between adjacent lobes and segments in human cadaveric lungs was undertaken to provide information for the later construction of a three-dimensional model of the segmental and subsegmental anatomy of the human lungs. This was performed by analyzing scanned cross-sections of the lungs after color-coded gelatin had been injected into segmental bronchi and the lungs embedded in gelatin and frozen. The resulting images provided information regarding the pattern of boundaries present between both lobes and segments.

SPET of a computerised model of diffuse lung disease

Emphysema is a common and debilitating disease that is the commonest cause of end-stage respiratory failure. Treatment is either by lung transplantation or by lung volume reduction surgery (LVRS) that improves the biomechanics of respiration. Patient selection for LVRS hinges on the demonstration of heterogeneous disease, predominantly involving the upper lobes, as a good surgical outcome is most likely in these patients. We used a virtual model of lung scintigraphy to compare planar with tomographic scintigraphy for the detection of diffuse lung disease. Lesions of the magnitude of the lung acinus, as well as larger and smaller lesions, were distributed throughout the lungs in volumes from 2% to 50%. Single-photon emission tomography does not add incremental value to planar images for the detection of diffuse lung disease.

Creation of a three-dimensional model of human segmental lung anatomy

OBJECTIVE

The investigation of pulmonary embolism using scintigraphic tomography requires a model of the internal architecture of the segments and subsegments in the human lung. Such a model has been developed by the segmentation and subsegmentation of an existing whole-body tissue-segmented phantom.

MATERIALS AND METHODS

By using information from suitably windowed human axial CT scans, combined with the information gained from the injection of color-coded dyes into the segmental bronchi of human cadaveric lungs, the lobar and segmental boundaries were added to the existing phantom. Further refinements were added from reports in the literature regarding the predominant pattern of subsegmental bronchi in a series of human cadavers, enabling the creation of subsegmental boundaries.

RESULTS

A digitized model of the segmental and subsegmental anatomy of the human lung was successfully created. External, or pleural, projections of the complex internal arrangement of the segments closely corresponded with the projections of the best available authorities on the subject.

CONCLUSION

The model provides the opportunity to address several issues germane to scintigraphy and important for diagnosing pulmonary embolic disease. In particular, the model allows the manipulation of three-dimensional data sets to explore issues of importance to tomographic lung scanning.

Single-photon emission tomography of a computerised model of pulmonary embolism

Planar pulmonary scintigraphy is currently the standard investigation for the diagnosis of pulmonary embolism. There are a number of problems with the technique, particularly in patients with an intermediate scan report under the PIOPED criteria. The technique is also under threat from the increasing use of spiral CT angiography. A putative improvement may be gained by use of tomography. The incremental value of tomography over planar studies was therefore evaluated in a virtual model of pulmonary scintigraphy. A model of the segmental anatomy of the lungs was developed from computed tomography, cadaveric human lungs and available anatomical texts. Counts were generated within the phantom by Monte Carlo simulation of photon emission. Eighteen single segmental lesions were interspersed with 47 subsegmental defects and displayed on an Icon reporting station. These were presented in the transaxial, sagittal and coronal planes to four experienced reporters to obtain assessment of defect size. Planar studies of the same defects were displayed to the same observers in the standard eight views with a normal study for comparison. With planar studies, the accuracy of estimation of defect size was 51% compared with 97% using tomographic studies. Defects in the medial basal segment of the right lower lobe were not identified in planar studies but were easily seen by all observers in the tomographic study. It is concluded that there is marked improvement in the accuracy of determination of defect size for tomographic studies over the planar equivalents. This is especially important in the lung bases, the most common reported site of pulmonary emboli. Tomography permits visualisation of defects in the medial basal segment of the right lung, which are not seen in planar studies.

Rationalization of the optimal views in planar lung scintigraphy

A knowledge of the segmental anatomy of the lungs is the cornerstone for interpreting lung scintigraphy. Many attempts have been made to determine the best views for the appreciation of segmental defects and various theories have been formulated to explain the mechanisms of this process. In earlier work, we hypothesized that the arrangements of the segments was the principal determinant of this process. However, data subsequently derived from work on a model of diffuse lung disease indicates that the external shape of the lobes and lungs may be the most significant contributor to the optimal views of the lungs.

Threshold of detection of diffuse lung disease

A scintigraphic model of the lungs was used to study the threshold of detection of diffuse disease of the lungs.

METHODS

Randomly distributed cold lesions of 4, 8, 12 and 16 mm3 block sizes were created, occupying 0%-50% of lung tissue in steps of 1%. These were submitted for reporting to five observers each with a normal study for comparison.

RESULTS

No observer detected lesions of 4-mm3 block size even when up to 50% of the lung was involved. All observers detected lesions of 8-mm3 block size when a mean of 27% of lung tissue was involved with lesions. As lesion size increased to 12 and 16 mm3, observers detected lesions when a mean of 10% and 6% of lung tissue was involved, respectively. Comparison between views for each observer showed that the lateral and anterior oblique views were used more often than the anterior, posterior oblique and posterior views.

CONCLUSION

This model suggests that pulmonary scintigraphy has the potential to detect a diffuse disease such as emphysema at an early stage of lung involvement. In general, small anatomic lesions appear to have more profound scintigraphic consequences. However, even scintigraphic lesions of the order of size of the pulmonary acinus are easily detected.

Enhanced accuracy and reproducibility in reporting of lung scintigrams by a segmental reference chart

The diagnostic probability of pulmonary embolic disease is based on the recognition of unmatched segmental perfusion defects. Although interobserver and intraobserver reproducibility have been studied, accuracy has been an elusive goal due to the lack of a gold standard. We investigated the accuracy and reproducibility of reporting in a virtual scintigraphic model of the lungs, with and without the use of a lung segmental reference chart.

METHODS

A Monte Carlo package was used to model lung scintigraphy from a digital phantom of the human lungs. An ideal lung segmental reference chart was created from the phantom. Five experienced nuclear medicine physicians reported a set of all possible defects involving 100% of a segment, without and with the chart. A further set of defects involving 45%-55% of a segment in the lower lobes was investigated using the chart.

RESULTS

There was a significant improvement in accuracy (from 48% to 72%) and intraobserver agreement (from 61% to 77%) with the chart. The accuracy of reporting defects in the upper and middle lobes was consistently better than that in the lower lobes. There was no significant difference between the accuracy of reporting large defects and that of reporting moderate defects in the lower lobes.

CONCLUSION

The lung segmental reference chart significantly improves both the accuracy and reproducibility of reporting lung scintigrams; however, although reporting in the lung bases is improved, absolute accuracy is substantially less than that in the upper and middle lobes. This emphasizes the need for caution because the lung bases are the most common site of embolic disease.

Variability of perceived defect size in virtual lung scintigraphy

The diagnosis of pulmonary embolism is based on the presence of mismatched segmental or subsegmental defects. An important axiom is the classification of defect sizes into small, moderate and large. Little information about the recognition and classification of such defects has been published. We undertook a study of the perception of defect size using a model of the virtual scintigraphic anatomy of the lungs to address this issue.

METHODS

Segmental anatomy of the lungs was modeled with CT, cadaveric lungs and standard anatomical tests. The emission, scatter and attenuation of photons were modeled within these virtual lungs and the surrounding tissues. Single segmental lesions, each 100% of a segment, were created in eight projections and submitted for blinded reporting by four experienced nuclear medicine physicians to obtain their assessment of the size of each defect on two occasions.

RESULTS

Of the 144 defects submitted for reporting, 15% were reported as <25% of a segment, 35% were reported as 25%-75% and 50% were reported as 75%-100%. The accuracy of each reporter and the intraobserver agreement were calculated; the weighted kappa value ranged from 0.34 to 0.60. The segmental defects that were most likely to be underestimated in size were in the right lower lobe.

CONCLUSION

It is clear that segmental defect sizes were underestimated, particularly in the right lower lobe. Although the intraobserver agreement in reporting was fair, the accuracy of estimation was only 50%. The variability and inaccuracy might be reduced by the use of a guide to segmental anatomy.

Optimization of the scintigraphic segmental anatomy of the lungs

Accurate and reproducible reporting of lung scintigraphy is predicated on a sound knowledge of the segmental anatomy of the lungs. A limited amount of hard data exists about the true segmental anatomy of the lungs. A virtual model of human lungs was created using a CT-based dataset and a Monte Carlo simulation technique to examine the optimal projections for the visualization of each segment in the lungs.

METHODS

Segmental anatomy of the lungs was modeled using CT, cadaveric lungs and standard anatomical texts. The emission, scatter and attenuation of photons was modeled within these virtual lungs and the surrounding tissues. Single segmental lesions were created in eight projections and submitted for blinded reporting to four experienced nuclear medicine physicians to obtain the best views for each segment.

RESULTS

The anterior and posterior oblique projections yielded the best views for 10 of 18 segments, with the laterals contributing four views, the anterior contributing two views and the posterior contributing one view. The majority of basal segments (six of nine) were best seen in the anterior and posterior oblique projections.

CONCLUSION

This model overcomes the major problems associated with experimentation in the normal human and has the potential to provide answers to the major problems of scatter, attenuation and "shine-through" in lung scintigraphy.

Recognition of subsegmental scintigraphic defects in virtual lung scintigraphy

A virtual model of the segmental scintigraphic anatomy of the lungs was used to investigate the threshold at which small defects are perceptible. A model of the segmental anatomy of the lungs was developed from a number of sources and counts generated within the phantom by Monte-Carlo simulation of photon emission. Multiple subsegmental defects were created in both lungs and submitted for blinded reporting to detect the presence of any defect. A total of 36 of the 47 (77%) defects were seen. Of those defects in the lower lobes, 16 of 22 (73%) were visible. All the defects in the left lung (n = 21) were visible, while 15 of 26 (58%) of the defects on the right were visible. In the lower lobe of the right lung, 4 of 10 defects were visible. The defects that were not visible were all in the right lung. We conclude that absolute size and location are critical in the perception of defects. The perception of defects was dependent on absolute defect size rather than the proportion of a segment involved. Defects less than 3% of the volume of a lung were not detected.

Simulation of the stripe sign in a scintigraphic model of the lungs

Using a virtual model of the lungs, we investigated the nature of the 'stripe sign' which is sometimes encountered in pulmonary scintigraphy. A model of the segmental anatomy of the lungs was developed from a number of sources and counts generated within the phantom by Monte-Carlo simulation of photon emission. Multiple segmental and subsegmental defects were created in both lungs and submitted for blinded reporting of the 'stripe sign'. Images were resubmitted for reporting with the contralateral lung removed. The stripe sign was reported in 32 of the 117 studies performed. Nearly half of these were present in defects involving approximately 25% of a segment and the sign was most commonly seen in the lateral projection. Removal of activity from the contralateral lung abolished the sign in only 2 of 32 cases. We conclude that shine through of activity from the contralateral lung is a mechanism rarely responsible for the stripe sign. Most occurrences of the sign are due to interposition of activity from unaffected areas of the same lung between the defect and the periphery of the lung. Orientation of the segments, particularly in the lung bases, accounts for the lateral projection being the most common view in which the sign is present.

Ulnar distribution of reflex sympathetic dystrophy due to compression of the brachial plexus by a primary venous malformation

An atypical variant of reflex sympathetic dystrophy (RSD) is presented in a 45 year old female with a vascular malformation of the right arm and chest wall. The mechanism was thought to be compression of the brachial plexus by the malformation. The unique scintigraphic features of this presentation of RSD in the ulnar arterial distribution are illustrated.