196 clinical J R Coll Physicians Edinb 2010; 40:196–200 doi:10.4997/JRCPE.2010.302 © 2010 Royal College of Physicians of Edinburgh INTRODUCTION Although most centres now employ computed tomography pulmonary angiography (CTPA) as the first- line investigation for clinically suspected pulmonary embolism (PE), 1–2 lung scintigraphy scans (LSS) remain a useful imaging modality 3 which is still widely used. 4–7 The PIOPED study suggested that high probability LSS are reliable in confirming PE (specificity 97%) and normal scans can reliably exclude PE (sensitivity 98%). 5 However, almost two-thirds of scans in the PIOPED study were of intermediate or low probability and associated with a 25–40% risk of PE. All LSS can be categorised as either high probability of PE, indeterminate probability of PE, or normal. The aim of this study was to test the hypothesis that survival would be inversely related to the radiological probability of PE as assessed by LSS performed at the time of presentation with clinically suspected PE. METHODS Results from 2,092 LSS performed at a single teaching hospital between April 1994 and August 2000 were prospectively entered onto a database and retrospectively reviewed. During this period LSS were the first-line diagnostic procedure used at this hospital for investigation of suspected PE. Computed tomography pulmonary angio- graphy was introduced towards the end of this period but was initially used to problem-solve non-diagnostic LSS. 3 Radiologists reported LSS using modified PIOPED criteria throughout this time period. 5 Scan results were recorded on the database at the time of scanning as normal, indeterminate or high probability.The indeterminate group combined intermediate and low probability categories described by the PIOPED investigators. Radiologists also recorded whether the corresponding chest X-ray (CXR) was normal or abnormal. All CXRs were performed within 24 hours prior to the LSS, where possible using a postero-anterior projection. An Ohio Nuclear Sigma 410 gamma camera was used for scintigraphy, with 80 MBq of technetium-labelled albumin macro-aggregates administered intravenously for perfusion imaging and inhalation of 80 MBq of Xenon-133 or Xenon-127 for ventilation studies when required. Mortality data were obtained, courtesy of Mr I Brown, from the General Register Office for Scotland (GROS), which registers all deaths in the country. If four personal Prognostic significance of the lung scintigraphy scan result and corresponding chest X-ray in patients with suspected pulmonary embolism ABSTRACT Aim: To determine whether the survival of patients with suspected acute pulmonary embolism (PE) relates to radiological probability of acute PE assessed using lung scintigraphy scans (LSS). Methods: Lung scintigraphy scan results from a venous thromboembolism database were categorised as high, indeterminate or low probability using the modified PIOPED criteria and corresponding chest X-rays (CXRs) as normal or abnormal. Mortality data on these cases were obtained from the General Register Office for Scotland, and survival was analysed using the Kaplan-Meier method. Results: Of the 1,818 LSS analysed, 941 (51.8%) were normal, 532 (29.3%) indeterminate and 345 (19.0%) high probability. After an adjustment for age and gender, no significant survival difference was found between patients with normal and high probability LSS (p=0.182). However, patients with indeterminate LSS had significantly lower survival than patients in the other groups. This difference persisted after adjustment for CXR result. Conclusions: Indeterminate LSS results are associated with a poor prognosis. Careful follow-up of patients with inderminate LSS would appear to be justified. KEYWORDS Lung scintigraphy scan, outcome, pulmonary embolism, survival, ventilation perfusion DECLARATION OF INTERESTS AJ Simpson is the Editor of The Journal of the Royal College of Physicians of Edinburgh. This article was submitted to, and handled exclusively by, the JRCPE’s Clinical Editor and has been peer-reviewed in line with usual JRCPE procedures. Paper 1 AS Al-Adhami, 2 AJ Simpson, 3 JH Reid, 4 M MacDougall, 5 JT Murchison 1 Specialist Registrar, West of Scotland Training Scheme; 2 Senior Clinical Lecturer in Respiratory Medicine, University of Edinburgh; 3 Consultant Radiologist, Department of Radiology, Borders General Hospital, Melrose; 4 Medical Statistician and Researcher in Education, Division of Community Health Sciences, University of Edinburgh Medical School; 5 Consultant Radiologist, Department of Radiology, Royal Infirmary of Edinburgh Correspondence to JT Murchison, Department of Clinical Radiology, Royal Infirmary of Edinburgh, Edinburgh EH16 4SU, UK tel. +44 (0)131 242 3775 e-mail john.murchison@luht.scot.nhs.uk