Detectability of hypervascularity in early dynamic PET depends on tracer kinetics: 18 F-FDG versus 68 Ga-DOTATOC in hepatic NET metastasis Contrast-enhanced computed tomography of a 54-yearold woman with pancreatic cancer showed a hypervascular liver lesion (upper row, Fig. 1). Suspecting a pancreatic neuroendocrine tumour with liver metastases, we separately performed positron emission tomography (PET) with 18 F-fluorodeoxyglucose (FDG), 245 MBq, and 68 Ga-DOTATOC (DOTATOC), 158 MBq, to exclude poor tumour differentiation and evaluate somatostatin receptors.Before conventional late static imaging, we performed early dynamic PET (edPET), with pictures continuously acquired for 90 s starting with bolus tracer injection. Both edPET image sets (second, third rows) depicted a very early signal increase with an inhomogeneous centre Liver International (2014)

The high image contrast of hypervascular NET metastases in early arterial phases suggests that edPET/CT can become a useful alternative in patients with contraindications to ceCT. The high density of somatostatin receptors did not seem to interfere with the detection of the lesion's hypervascularization.

A 70-year-old male patient was admitted to our dermatology outpatient clinic with newly developed personality changes and signs of hypoxemia. His anti-p200 Pemphigoid was treated with Dapsone for a few weeks. Due to generalized tonic-clonic seizure with a subsequent Glasgow Coma Scale of 5 points and a peripheral oxygen saturation not exceeding 88% under conditions of high-flow nasal cannula, he was intubated by the emergency team and transferred to the intensive care unit. Comprehensive tests were performed, but Dapsone-induced methemoglobinemia remained the exclusive explanation for the observed scenario, although arterial MetHb analysis showed a peak value of only 6%. The patient recovered shortly after repeated infusions of Methylene blue and Ascorbate, and cessation of Dapsone. We provide an overview of the pathophysiology, diagnostic procedures, and possible explanations for this case of Dapsone-induced methaemoglobinaemia. In conclusion, our case report provides evidence that even mild chronic methemglobinemia can induce severe clinical symptoms.