Hans Van der Wall

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

Abstract. 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.

Transcutaneous electrical nerve stimulation for postoperative pain relief after total knee arthroplasty

Transcutaneous electrical nerve stimulation (TENS) has been used to treat chronic pain syndromes and has been reported to be of some utility in the treatment of postsurgical pain. A randomized, blinded, placebo-controlled trial was designed to evaluate the utility of TENS after total knee arthroplasty. Patients were randomly enrolled into patient-controlled anesthesia (PCA) alone, PCA plus TENS, or PCA plus sham TENS. The cumulative dose of morphine by PCA for each group was used as the end-point of the study. There was no significant reduction in the requirement for patient-controlled analgesia with or without TENS. We conclude that there is no utility for TENS in the postoperative management of pain after knee arthroplasty.

Yttrium 90 Bremsstrahlung SPECT/CT scan demonstrating areas of tracer/tumour uptake

A 64-year-old woman with known metastatic colon carcinoma of the right lobe of the liver was referred for therapy with yttrium labeled SIR spheres. The hepatic artery was cannulated via a right femoral percutaneous approach. The hepatic angiogram demonstrated good clearance of the right hepatic artery from the gastro duodenal vessels allowing a good margin of safety for injection of the SIR spheres. Three GBq yttrium labeled SIR spheres were injected, and repeated angiography showed little evidence of reflux of contrast into the gastroduodenal circulation. The patient experienced some discomfort and pain that required analgesia. Subsequently, whole body planar images and SPECT/CT were acquired on a Philips Precedence camera. The camera peaked Y-90 at 90 keV with a 30% window. Medium energy collimators were used with a 256×256 matrix at 35 s a step with 64 projections. CT parameters were low dose attenuation correction and localization at 50mAs. Images were then attenuated corrected and filtered with Philip’s new Astonish filter with 3 iterations and a subset of 8. Images were then coregistered with CT using Syntegra software. The tomographic images (see figure top row CT, middle row SPECT, bottom row fusion) demonstrated areas of maximum tracer uptake which correlate anatomically with sites of maximum tumour density [1], unlike in traditional bremsstrahling images [2] which offer little anatomical detail.

Infection or Allergy in the Painful Metal-on-Metal Total Hip Arthroplasty?

Metal-on-metal articulations are increasingly used in total hip arthroplasty. Patients can be sensitive to metal ions produced by the articulation and present with pain or early loosening. Infection must be excluded. Correct diagnosis before revision surgery is crucial to implant selection and operation planning. There is no practical guide in the literature on how to differentiate between allergy and infection in a painful total hip arthroplasty. We present the history, clinical findings and hip scores, radiology, serology, hip arthroscopy and aspirate results, labeled white cell scan, revision-hip findings, histology and clinical results of a typical patient with a hypersensitivity response to a metal-on-metal hip articulation, and how results differ from patients with an infected implant. A practical scheme to investigate patients with a possible hypersensitivity response to an implant is presented.

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.

Rhabdomyolysis resulting from interaction of simvastatin and clarithromycin demonstrated by Tc-99m MDP scintigraphy

AbstractStatins (3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors) are well known to be able to cause a variety of muscle-related complications, the most serious of which is rhabdomyolysis. Rhabdomyolysis is a syndrome characterized by muscle pain with creatine kinase levels 10 times highe

Prospective evaluation of the impact of diabetes and left ventricular hypertrophy on the relationship between ischemia and transient ischemic dilation of the left ventricle on single-day adenosine Tc-99m myocardial perfusion imaging

Background. Diabetes and left ventricular hypertrophy (LVH) can cause coronary flow reserve abnormalities in the absence of coronary artery disease (CAD). We sought to evaluate the impact of LVH and diabetes on the relationship between ischemia, severe CAD, and transient ischemic dilation (TID) on adenosine myocardial perfusion imaging (MPI).Methods and Results. We prospectively recruited 157 patients referred for routine single-day adenosine technetium 99m MPI. LVH was assessed by use of transthoracic echocardiography. A ratio of 1.19 or greater on MPI defined TID in men and 1.31 or greater in women. Summed difference scores were determined by use of a 17-segment 5-point scoring system. TID was present in 22 of 157 patients (14%), diabetes in 54 of 157 (34%), and LVH in 42 of 157 (27%). By multivariate logistic regression, LVH, ischemia (summed difference score >2), and diabetes were independently predictive of TID. The incidence of TID was stratified by the presence or absence of diabetes and/or LVH in those with ischemia on MPI (8/8 [100%] vs 0/11 [0%], P<.002) or severe CAD on angiography (5/7 [71%] vs 0/8 [0%], P<.01). All those with TID (22/22 [100%]) had either diabetes or LVH (or both).Conclusion. Although this study confirms the association between TID and both ischemia and severe CAD, all patients with TID had diabetes, LVH, or frequently, both, suggesting that the pathophysiology of these disease processes may play an integral role in the manifestation of TID on adenosine MPI.

SPECT/CT of femeroacetabular impingement.

Femoroacetabular impingement is a recently described condition thought to be associated with early onset osteoarthritis. We describe 2 cases of femoroacetabular impingement that were initially unrecognized despite multimodality imaging, including radiographs, MRI, and scintigraphy. The scintigraphic appearance may mimic avascular necrosis. There are limited reports of femoroacetabular impingement in the nuclear medicine literature. We propose that the finding of increased uptake in the superior femoral neck associated with osteoarthritic uptake involving the superior hip joint suggests the diagnosis of either cam or mixed cam-pincer impingement.

Scintigraphy of Benign Bone Disease

Bone scintigraphy is ideally suited for the investigation of benign bone disease as it functions at a physiological level. It is freely available and has whole-body capability and high-contrast resolution. When coupled with single-photon emission computed tomography/computed tomography (SPECT/CT), it can be utilized to provide precise anatomical localization, attenuation correction, and therefore better lesion localization. A considerable volume of data has accumulated on the role of bone scintigraphy in trauma and its complications, overuse injuries, vascular disease of bone, metabolic bone diseases, and a variety of other disorders. This article is an overview of the established applications and signposts of potential future applications with the increasing prevalence of SPECT/CT devices and technical advances in attenuation correction, collimator modeling, and resolution recovery software.

Hypertrophic pulmonary osteoarthropathy without clubbing of the digits.

Abstract. Hypertrophic osteoarthropathy (HOA) typically occurs concurrently with clubbing of the digits, with isolated HOA being reported only rarely. We report two patients with intra-thoracic malignancy in whom HOA, demonstrated on bone scintigraphy, developed in the absence of clubbing. We also report the novel observation of involvement of the metatarsal and metacarpal bones by HOA.