H. Van Der Wall

Looking beyond low bone mineral density: multiple insufficiency fractures in a woman with post-menopausal osteoporosis on alendronate therapy.

Insufficiency fractures occur most commonly in the pelvic girdle and in the sacrum, followed by the tibia and the femoral neck. Insufficiency fractures of the femoral diaphyses are rare, with only few reported cases in the literature. The strongest associations exist with untreated osteoporosis. We describe an unusual case of multiple insufficiency fractures in a 73-yr-old Chinese woman who presented with a 10-month history of bilateral groin pain and difficulty with walking in the absence of trauma, diagnosed 18 months following the commencement of anti-resorptive therapy with alendronate. The pathogenesis of such insufficiency fractures is poorly understood, but next to low bone mineral density and micro-architectural damage likely involves other components such as changes in bone turnover and patient-related factors (e.g. non-compliance). This case report and review of the literature draws attention to some of the challenges in the diagnosis and management of such rare insufficiency fractures.

Tc-99m Stannous Colloid-Labeled Leukocyte Scintigraphy in the Evaluation of the Painful Arthroplasty

The aim of this study was to evaluate the utility of scintigraphy using leukocytes labeled with Tc-99m stannous colloid in the assessment of painful arthroplasties. The results of three-phase bone scintigraphy and imaging with Tc-99m-labeled leukocytes in 40 patients with painful joint prostheses, requiring the exclusion of infection are reported. Results were compared with microbiologic culture and/or long-term clinical review. Bone scintigraphy had a sensitivity of 100%, a specificity of 64%, and a diagnostic accuracy of 73% in detecting prosthetic infection. Tc-99m-labeled leukocytes yielded a sensitivity of 70%, a specificity of 100%, and a diagnostic accuracy of 93%. Leukocyte scintigraphy improves the specificity of bone scintigraphy in the assessment of the painful prosthetic joint. A positive study is highly suggestive of infection and warrants appropriate treatment.

Scintigraphic measurement of tracheal mucus velocity in vivo

Mucociliary clearance (MCC) is an important mechanism for removing inhaled particles, secretions and cellular debris from the respiratory tract. Here, a direct measurement of tracheal mucus velocity (TMV) for assessment of MCC, suitable for clinical and research use, is reported, and a comparison is made of TMV in normal subjects and patients with chronic obstructive pulmonary disease (COPD). A 0.1‐mL bolus of radiolabelled (2–5 MBq), technetium-labelled macroaggregated human albumin (99mTc MAA) was injected through the cricothyroid membrane into the trachea of 20 young (<50 yrs) and 12 older (>50 yrs) normal subjects and 34 patients with COPD. Repeat studies were carried out in 13 normal subjects and 16 COPD patients. Movement of the bolus in the trachea was recorded (15 min) using a gamma camera interfaced to a computer. Data were analysed using specifically designed software. The test was well tolerated by subjects and patients, and no significant adverse events were reported. No significant differences were observed between data recorded from different regions of the bolus (leading edge, peak, trailing edge) by analysis of variance (ANOVA). Bland-Altman plots of the repeat studies indicated that data were more variable in normal subjects (coefficient of repeatability (COR) 10.3 mm·min−1) than in COPD patients (COR 5.5 mm·min−1). TMV (mean±sd) in young normal subjects (n=20) was 10.7±3.5 mm·min−1. TMV was reduced in older normal subjects (n=12; 6.5±2.6 mm·min−1) and further reduced in COPD (n=34; 2.1±2.7 mm·min−1). In conclusion, this technique can be used to measure tracheal mucus velocity rapidly and safely in healthy subjects and patients with respiratory tract disease. This study has confirmed that tracheal mucus velocity declines with age and is further impaired in patients with chronic obstructive pulmonary disease.

Occurrence of pulmonary thromboembolism immediately after arthroplasty

Introduction Respiratory complications are common after arthroplasty, with pulmonary thromboembolic disease (PTE) and fat emboli being the most serious. A scintigraphic study was designed to assess the occurrence of both diseases. A prospective tomographic study of perfusion was performed within 24 h of arthroplasty. Details of the detection of fat embolism will be presented elsewhere. Methods Patients with previous PTE were excluded. Tomographic lung studies were acquired after 99mTc-macroaggregated albumin injection. Pre- and post-operative arterial blood gases (ABGs) and relevant chest radiography/computed tomography scans were obtained. ABGs were analysed as the difference in alveolar-arterial oxygen gradients, pre- and post-operatively (DA-a). Results Forty patients were studied (16F, 24M) with a mean age of 71 years (range 36-88 years). Of these, 16 were hip and 24 knee arthroplasties. PTE was detected in 25 of 38 (66%) patients evaluated. The value of DA-a was significantly different between patients with PTE and without PTE (P>0.05). Administration of prophylactic pre-operative low molecular weight heparin makes no difference to the early onset of PTE. Conclusion There is a high incidence of PTE immediately after arthroplasty.

A novel view for the scintigraphic assessment of the elbow

Using any imaging modality, the elbow is a complex joint to evaluate. The use of scintigraphy in the evaluation of the effects of acute or chronic trauma has largely been confined to epicondylitis. We developed a skyline view of the elbow that minimized the effect of overlap and assessed its incremental value in the scintigraphic assessment of several pathological conditions. Thirty-four abnormalities were evaluated in 20 patients with a range of pathologies, including epicondylitis, ligamentous avulsion injury, articular injury, fractures and synovitis. The incremental value of addition of the skyline view to the standard views was assessed in addition to the overall accuracy of scintigraphy. Overall, scintigraphy detected 27 of 34 abnormalities, with the standard views of the elbow accurately identifying 15 and the skyline view 23 abnormalities. This gave the skyline view an incremental value of 24% over the standard views. In conclusion, scintigraphy has the potential to identify a greater range of pathologies in the elbow than previously reported, due to the addition of the skyline view to the standard views.

A study of technegas employing X-ray photoelectron spectroscopy, scanning transmission electron microscopy and wet-chemical methods

SummaryScanning transmission electron microscopy (STEM), coupled with energy dispersive X-ray analysis (EDS), X-ray photoelectron spectroscopy (XPS) or radionuclear chemical methods, indicates that the active agent in Technegas is either polymeric TcO2 [i.e. (TcO2)n] or (TcO2)n bound to a carbon nanoparticle. The particle size observed using STEM is in good agreement with other published results. XPS has also been used to investigate technetium residues remaining on spent crucibles. The chemical form of technetium in this residue is quite different to the form detected in the aerosol particles. We conclude that the small fraction that migrates into the crucible framework upon resistive heating is reduced to either metallic technetium or carbidic forms, with the remaining nuclide evaporating as (TcO2)n with or without carbon before complete reduction can occur.

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

Abstract 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.

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.

The use of SPECT in the diagnosis of epiphyseal osteoid osteoma

An osteoid osteoma, which rarely occurs in an intraeplphyseal site, was identified by SPECT imaging in the proximal tibial epiphysis of a boy who had lower back pain, which had not been explained by extensive prior investigations.

Scintigraphic assessment of the acetabulum after arthroplasty with reference to cup geometry

A unique scintigraphic appearance has been noted in uncomplicated hip prostheses which have the acetabular component inserted after under-reaming or where a cone-shaped cup is inserted. We hypothesized that the pattern of increased uptake around the superior and inferior third of the cup with relatively reduced uptake in the medial third is due to preferential loading of the rim of the cup. A prospective study of ten patients with uncomplicated hip prostheses supports the hypothesis.