ABSTRACT
Ocular melanoma is classified under the category of noncutaneous melanomas. Noncutaneous melanomas are relatively rare. Ocular melanoma commonly arises from choroid. Conjunctival melanoma is a rare but potentially lethal form of ocular melanoma. It can invade locally. Systemic spread is seen in up to 25% of cases, often associated with lymph node involvement. Metastatic sites include the lungs, liver, gastrointestinal tract, and the central nervous system. F-18 fluorodeoxyglucose positron emission tomography/computed tomography (F-18 FDG PET-CT) scanning is indicated for staging cutaneous melanoma patients. However, few studies have evaluated its role in the management of conjunctival melanoma. This case highlights the use of F-18 FDG PET/CT for imaging, preoperative staging, and evaluation for metastasis in conjunctival melanoma.
Subject(s)
Conjunctival Neoplasms/pathology , Fluorodeoxyglucose F18/metabolism , Melanoma/pathology , Neoplasm Recurrence, Local/pathology , Positron Emission Tomography Computed Tomography/methods , Conjunctival Neoplasms/diagnostic imaging , Conjunctival Neoplasms/metabolism , Humans , Male , Melanoma/diagnostic imaging , Melanoma/metabolism , Middle Aged , Neoplasm Recurrence, Local/diagnostic imaging , Neoplasm Recurrence, Local/metabolism , Prognosis , Radiopharmaceuticals/metabolismABSTRACT
Frostbite or cold burn is the medical condition in which localized damage is caused to exposed skin and subcutaneous tissue due to freezing. Frostbite most likely involves body parts farthest from the heart and those with large exposed areas. At or below 0 °C (32 °F), blood vessels close to the skin start to constrict, and blood is shunted away from the extremities via the physiological feedback action of glomus bodies. This peripheral vasoconstriction helps to conserve core body temperature. In extreme cold, or when certain parts of the body are exposed to cold conditions for long periods, this protective mechanism can reduce blood flow in some areas of the body to dangerously low levels. This is followed by crystallisation of water in the tissue and subsequent death of tissues in the affected areas. In this case series, we highlight the importance of a 99mtechnetium methylene diphosphonate (99mTc MDP) triple phase bone scan in cases of severe frostbite to precisely delineate the ischaemic and reperfusion zones, so as to help the surgeons in carefully deciding if amputation is required and the level of amputation in such cases.
ABSTRACT
AIM: To determine the diagnostic reliability of (18)F-FDOPA, (13)N-Ammonia and F18-FDG PET/CT in primary brain tumors. We evaluated the amino acid and glucose metabolism of brain tumors by using PET with (18)F-FDOPA, (13)N-Ammonia and F18-FDG PET/CT. MATERIALS AND METHODS: Nine patients undergoing evaluation for brain tumors were studied. Tracer uptake was quantified by the use of standardized uptake values and the ratio of tumor uptake to normal identical area of contra lateral hemisphere (T/N). In addition, PET uptake with (18)F-FDOPA was quantified by use of ratio of tumor uptake to striatum uptake (T/S). The results were correlated with the patient's clinical profile. RESULTS: Both high-grade and low-grade tumors were well visualized with (18)F-FDOPA. The sensitivity for identifying tumors was substantially higher with (18)F-FDOPA PET than with F18-FDG and (13)N-Ammonia PET as determined by simple visual inspection. The sensitivity for identifying recurrence in low grade gliomas is higher with (13)N-Ammonia than with F18-FDG. CONCLUSION: (18)F-FDOPA PET is more reliable than F18-FDG and (13)N-Ammonia PET for evaluating brain tumors.