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Introduction
Adenocarcinoma is a type of lung cancer in which the tumour cells form recognisable glandular structures under the microscope. These cells belong to the non-small cell lung cancer (NSCLC) group. At the time of diagnosis they have the highest likelihood of being localised and they show the best response to treatment with surgery or radiation therapy.
Patient history
A 68-year-old male patient presented for a positron emission tomography/computed tomography (PET/CT) diagnostic study with an interesting history. In 1969, he received mantle radiotherapy treatment for Hodgkin's lymphoma. Despite the removal of a couple of basal cell carcinomas, he remained well until early 2003. In February, the patient presented with gastric symptoms and had noted blood streaking in his sputum without a cough. An endoscopy showed no abnormality.
Following this test, the patient noticed weight loss and continuing episodes of blood in the sputum and was referred for a chest x-ray that revealed a mass in the left lung. This appearance was confirmed on CT with a very extensive consolidative mass demonstrated. Histology from a biopsy of this mass showed cellular changes which were thought to be a consequence of previous radiotherapy, with no evidence of malignancy. The likely diagnosis was a chest infection and the patient was given one course of antibiotics, after which he reported feeling much better.
In early April 2003, following the development of a cough and change in voice, the patient was referred to the Alliance Medical Imaging Centre, London, for a PET/CT scan to try to determine whether any of the large left lung mass was a tumour. The clinical impression was that there might be a proximal obstructing tumour with extensive consolidation.
Investigative procedure
Diagnosis of cancer has conventionally relied on anatomical imaging with CT or MRI. These modalities undoubtedly provide exquisite anatomical information and detect structural abnormalities within tissue with a high accuracy, which plays a large part in surgical guidance and other treatment procedures. However, these techniques have limitations in differentiating between benign and malignant cells in diseased tissue. Molecular imaging techniques such as PET rely on abnormal metabolic activity which precedes any structural change and can therefore aid diagnosis of malignancy in the body.1
18F-fluoro-2-deoxyglucose (18FDG) is a sensitive tracer which concentrates in malignant tissue...