Background: The role of nuclear medicine in diagnosing pulmonary embolism (PE) is continuously evolving owing to advancements in imaging methods. In recent years, ventilation/perfusion single photon emission computed tomography-computed tomography (V/Q SPECT/CT) has established a synergistic role over conventional V/Q planar scintigraphy and V/Q SPECT in diagnosing pulmonary embolism. Objectives: In this study, we aimed to assess the incremental value of V/Q SPECT/CT over conventional V/Q planar scintigraphy and V/Q SPECT, and to determine if Q only-SPECT/CT without the conventional ventilation component could replace the current imaging protocol in diagnosing pulmonary embolism. Methods: We retrospectively assessed 73 patients with suspicion of pulmonary embolism who had undergone/Q planar scintigraphy, V/Q SPECT and V/Q SPECT/CT consecutively. Combination of clinical follow-up, laboratory test results and correlative imaging were used as reference standard. Q-only SPECT/CT datasets were then analysed separately without the V-planar, V-SPECT and V-SPECT/CT datasets. Results: A total of 66 patients fulfilled our initial inclusion and exclusion criteria, with 23 patients as positive for PE and 43 patients ruled out of having PE based on the reference standard. Sensitivity and specificity for V/P planar scintigraphy, V/Q SPECT, and V/Q SPECT-CT were 86.9% and 39.5%, 91.3% and 55.8%, and 100% and 97.6% respectively. Overall, SPECT/CT resulted in significantly higher diagnostic accuracy than planar and SPECT imaging respectively (p<0.05). Q-only SPECT/CT significantly over diagnosed pulmonary embolism in 12 patients (p<0.05). Conclusion: Adding V/Q SPECT/CT to the algorithm of PE significantly improves the sensitivity and specificity. However, by eliminating the ventilation component, the diagnostic accuracy is significantly reduced.

A patient with underlying rectosigmoid cancer presented with solitary bone lesion at left tibia. Eventhough, solitary bone metastasis particularly in the appendicular skeleton is rare in rectosigmoid cancer, it remained as the most likely initial diagnosis. However, after further characterisation by various imaging modalities and subsequent biopsy, the lesion proved to be an osteofibrous dysplasia like-adamantinoma (OFD-like adamantinoma), which is a subtype of adamantinoma. Being a rare primary bone tumour, adamantinoma and its subtypes are infrequently thought of in the initial working diagnosis of a patient with known malignancy who presents with solitary bone lesion. We present here a case of OFD-like adamantinoma in a patient with underlying rectosigmoid cancer, which mimic a metastastic bone lesion.