Mucus clears from the trachea in a helix: a new twist to understanding airway diseases.

BACKGROUND: Mucociliary clearance (MCC) is critical to lung health and is impaired in many diseases. The path of MCC may have an important impact on clearance but has never been rigorously studied. The objective of this study is to assess the three-dimensional path of human tracheal MCC in disease and health. METHODS: Tracheal MCC was imaged in 12 ex-smokers, 3 non-smokers (1 opportunistically imaged during acute influenza and repeated after recovery) and 5 individuals with primary ciliary dyskinesia (PCD). Radiolabelled macroaggregated albumin droplets were injected into the trachea via the cricothyroid membrane. Droplet movement was tracked via scintigraphy, the path of movement mapped and helical and axial models of tracheal MCC were compared. MEASUREMENTS AND MAIN RESULTS: In 5/5 participants with PCD and 1 healthy participant with acute influenza, radiolabelled albumin coated the trachea and did not move. In all others (15/15), mucus coalesced into globules. Globule movement was negligible in 3 ex-smokers, but in all others (12/15) ascended the trachea in a helical path. Median cephalad tracheal MCC was 2.7 mm/min ex-smokers vs 8.4 mm/min non-smokers (p=0.02) and correlated strongly to helical angle (r=0.92 (p=0.00002); median 18o ex-smokers, 47o non-smokers (p=0.036)), but not to actual speed on helical path (r=0.26 (p=0.46); median 13.6 mm/min ex-smokers vs 13.9 mm/min non-smokers (p=1.0)). CONCLUSION: For the first time, we show that human tracheal MCC is helical, and impairment in ex-smokers is often caused by flattened helical transit, not slower movement. Our methodology provides a simple method to map tracheal MCC and speed in vivo.

Glossopharyngeal insufflation causes lung injury in trained breath-hold divers.

BACKGROUND AND OBJECTIVE: Glossopharyngeal insufflation (GI) is a technique practised by competitive breath-hold divers to enhance their performance. Using the oropharyngeal musculature, air is pumped into the lungs to increase the lung volume above physiological TLC. Experienced breath-hold divers can increase their lung volumes by up to 3 L. Although the potential for lung injury is evident, there is limited information available. The aim of this study was to examine whether there is any evidence of lung injury following GI, independent of diving. METHODS: Six male, competitive breath-hold divers were studied. CT of the thorax was performed during breath-holding at supramaximal lung volumes following GI (CT(GI)), and subsequently at baseline TLC (CT(TLC)). CT scans were performed a minimum of 3 days apart. Images were analysed for evidence of pneumomediastinum or pneumothorax by investigators who were blinded to the procedure. RESULTS: None of the subjects showed symptoms or signs of pneumomediastinum. However, in five of six subjects a pneumomediastinum was detected during the CT(GI). In three subjects a pneumomediastinum was detected on the CT(GI), but had resolved by the time of the CT(TLC). In two subjects a pneumomediastinum was seen on both the CT(GI) and the CT(TLC), and these were larger on the day that a maximal GI manoeuvre had been performed. The single subject, in whom a pneumomediastinum was not detected, was demonstrated separately to not be proficient at GI. CONCLUSIONS: Barotrauma was observed in breath-hold divers who increased their lung volumes by GI. The long-term effects of this barotrauma are uncertain and longitudinal studies are required to assess cumulative lung damage.

Radionuclide bone scintigraphy in sports injuries.

Bone scintigraphy is one of the mainstays of molecular imaging. It has retained its relevance in the imaging of acute and chronic trauma and sporting injuries in particular. The basic reasons for its longevity are the high lesional conspicuity and technological changes in gamma camera design. The implementation of hybrid imaging devices with computed tomography scanners colocated with the gamma camera has revolutionized the technique by allowing a host of improvements in spatial resolution and anatomical registration. Both bone and soft-tissue lesions can be visualized and identified with greater and more convincing accuracy. The additional benefit of detecting injury before anatomical changes in high-level athletes has cost and performance advantages over other imaging modalities. The applications of the new imaging techniques will be illustrated in the setting of bone and soft-tissue trauma arising from sporting injuries.

Bone scintigraphy predicts outcome of steroid injection for plantar fasciitis.

UNLABELLED: Plantar fasciitis is a common cause of foot pain and may be disabling. Although localized injection is painful, anesthetics or corticosteroids can relieve symptoms well. Bone scintigraphy can confirm the diagnosis. We hypothesized that blood-pool abnormalities could provide prognostic information on the response to such injections. METHODS: We devised scintigraphic criteria that graded the blood-pool abnormalities as being localized to the plantar enthesis, being localized to half the length of the aponeurosis, or involving the whole aponeurosis. We evaluated 24 patients with an established diagnosis of plantar fasciitis, 8 of whom had bilateral disease, leading to a total of 32 feet injected. RESULTS: After injection, pain was relieved either completely or nearly completely in 20 feet. The other 12 feet had short-term or no improvement, with persistent pain and loss of function at 4-5 wk after injection. Of the 20 feet responding to injection, 14 had focal hyperemia on blood-pool images and 6 had minimal extension into the proximal third of the plantar soft tissues. No patient with diffuse hyperemia in the plantar fascia had a response (5/12 feet). On the delayed images of the 20 responders, mild inferior calcaneal uptake was seen in 8 feet, moderate uptake in 6, and severe uptake in 6. These groups did not significantly differ (P > 0.05). The blood-pool studies had good reproducibility, with a kappa-value of 0.64. CONCLUSION: Critical evaluation of plantar blood-pool images provides prognostic information on the response to localized injection into the enthesis. Reporting such studies is simple and reproducible.

Blunt trauma soft-tissue uptake on skeletal scintigraphy.

Muscle and soft-tissue uptake have been described numerous times in the literature in patients undergoing Tc-99m methylene diphosphonate skeletal scintigraphy following trauma. Many of these traumas range from electrical burns, intramuscular injections, sports-related trauma, and overexercising, to actual physical damage resulting in superficial bruising and skin discoloration. In this case the patient presented with continuing low back pain after falling down some stairs. Although the scan was essentially normal for bony trauma, subtle soft-tissue uptake was detected that was enhanced with the addition of single photon emission computed tomographic imaging and surface rendering.

A critical appraisal of pinhole scintigraphy of the ankle and foot.

BACKGROUND: Scintigraphy is an established imaging technique for injuries of the ankle and foot that are not apparent on plain radiographs. The scintigraphic technique has varied, with planar and pinhole images being used. MATERIALS AND METHODS: The incremental value of pinhole scintigraphy over planar imaging was studied in 16 patients with established diagnoses. Inter-reporter reproducibility was also measured. RESULTS: Pinhole scintigraphy improved the diagnostic specificity in nearly one half of the patients (48%). It did not contribute substantial information in 46% and led to confusion in the diagnosis of one patient. Inter-reporter agreement was good, with a kappa value of 0.78. Diagnoses varied from fractures of the talar dome to avulsion fractures of the malleoli and impingement syndromes. CONCLUSIONS: Pinhole images add a significant incremental value to planar scintigraphy of the foot and ankle. Although this had been perceived intuitively in the past, it has not been critically evaluated. The technique has good inter-reporter agreement.

Scintigraphy of injuries to the distal tibiofibular syndesmosis.

Ankle sprains are a common injury and may occur in as many as 75% of sporting participants. More complex injuries involving a rotational component may lead to injury of the interosseous membrane, its supporting ligaments, or the tibial plafond, compromising the integrity of the ankle mortice. Four such cases that show the scintigraphic manifestation of the injury are presented. In addition to the standard planar views of the ankles, special magnified anterior views were obtained with the feet in internal rotation of 25 degrees to 35 degrees. These special views facilitated the diagnoses.

Distinguishing scintigraphic features of spondylolysis.

A scintigraphic pattern of increased uptake was observed in the pedicles of the affected segment and a triangular pattern of uptake in the sagittal projection of tomographic studies of pars fractures. It was hypothesised that these observations were specific for pars fractures. A retrospective study of 25 young athletes (age 9-16 years) with a variety of spinal disorders was undertaken. Back pain was present for an average of 4 months. Diagnosis was confirmed by radiologic studies and/or response to treatment. All 15 children with spondylolysis had evidence of increased uptake in the ipsilateral or contralateral pedicle. None of the other causes of back pain showed this pattern. A specific triangular pattern of uptake was seen in the sagittal view in these patients. The authors describe two unique features of spondylolysis that add to the confidence with which the scintigraphic diagnosis may be made.