A B S T R A C T PurposeThere is currently no imaging biomarker for metastatic prostate cancer. The bone scan index (BSI) is a promising candidate, being a reproducible, quantitative expression of tumor burden seen on bone scintigraphy. Prior studies have shown the prognostic value of a baseline BSI. This study tested whether treatment-related changes in BSI are prognostic for survival and compared BSI to prostate-specific antigen (PSA) as an outcome measure. Patients and MethodsWe retrospectively examined serial bone scans from patients with castration-resistant metastatic prostate cancer (CRMPC) enrolled in four clinical trials. We calculated BSI at baseline and at 3 and 6 months on treatment and performed univariate and bivariate analyses of PSA, BSI, and survival. ResultsEighty-eight patients were scanned, 81 of whom have died. In the univariate analysis, the log percent change in BSI from baseline to 3 and 6 months on treatment prognosticated for survival (hazard ratio [HR], 2.44; P ϭ .0089 and HR, 2.54; P Ͻ .001, respectively). A doubling in BSI resulted in a 1.9-fold increase in risk of death. Log percent change in PSA at 6 months on treatment was also associated with survival (HR, 1.298; P ϭ .013). In the bivariate analysis, change in BSI while adjusting for PSA was prognostic at 3 and 6 months on treatment (HR, 2.368; P ϭ .012 and HR, 2.226; P ϭ .002, respectively), but while adjusting for BSI, PSA was not prognostic. ConclusionThese data furnish early evidence that on-treatment changes in BSI are a response indicator and support further exploration of bone scintigraphy as an imaging biomarker in CRMPC.

A positron emission tomography (PET)/CT examination performed on an elderly man, known to have Merkel cell carcinoma (MCC) resected 3 years earlier, showed abnormal fludeoxyglucose 18F (FDG) uptake within new masses in the right and left adrenal gland with standard uptake value (SUV) measurements of 6.4 and 9.3, respectively, which histologically represented metastatic MCC (figure 1). MCC is a rare neuroendocrine tumour of the cells of the basal layers of the epidermi.1 The main risk factor is exposure to sunlight and ultraviolet light. Most patients (70-80%) present with localised disease. Even with local excision, the incidence of distant metastatic disease (18-52%), regional nodal metastases (45-91%) and local recurrence (27-60%) are high and usually occur within 2 years of the diagnosis. Besides local and recurrent lymph nodes, metastatic disease has been reported in the adrenal gland, liver, mediastinum, peritoneum, lung and subcutaneous fat. There is no agreed upon imaging modality for evaluation of MCC although nuclear imaging modalities using lymphoscintigraphy for evaluation of sentinel nodes and somatostatin receptor scintigraphy for evaluation of local and distant metastases and recurrence have been used. There has also been an increasing role of PET/CT in evaluating MCC. PET has been shown to detect occult disease that was not detected by physical examination, CT or somatostatin receptor scintigraphy.

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DESCRIPTIONAn elderly male who initially presented with a gangrenous left lower extremity and underwent bypass graft surgery was anticoagulated and presented with bloody bowel movements. A tagged 99mTc red blood cell scan was obtained using the Ultratag technique. This examination is recognised as the best screening method to detect active gastrointestinal bleeds. 1 -3 The sensitivity of this nuclear medicine study for detecting active gastrointestinal bleeds is 93%, with a specifi city of 95% and an overall accuracy of 94%. 4 This scan demonstrated activity within a tubular structure in the region of the ileum ( fi gure 1A ). This area of activity increased in intensity and moved antegrade towards the ileocecal valve, with a characteristic hook-like appearance ( fi gure 1B ). The patient was taken directly to surgery where an arteriovenous malformation was discovered within the ileum as the source of haemorrhage. The patient had an uneventful recovery with complete resolution of the gastrointestinal bleed. Competing interests